Wireless Technology Terms Glossary and Dictionary

OG refers to pre-cellular mobile telephony technology. These mobile telephones were usually mounted in cars or trucks. Typically, the transceiver (transmitter-receiver) is mounted in the vehicle trunk and attached to the "head" (dial, display, and handset) mounted near the driver seat.
64 QAM: 16ary Quadrature Amplitude Modulation
16ary Quadrature Amplitude Modulation (16-QAM), one of the forms of QAM, is a modulation scheme. In QAM, the constellation points are usually arranged in a square grid with equal vertical and horizontal spacing, although other configurations are possible. Since in digital telecommunications the data is usually binary, the number of points in the grid is usually a power of 2 (2,4,8...). Since QAM is usually square, the most common forms of QAM are 16-QAM, 64-QAM, 128-QAM and 256-QAM. By moving to a higher-order constellation, it is possible to transmit more bits per symbol. However, if the mean energy of the constellation is to remain the same (by way of making a fair comparison), the points must be closer together and are thus more susceptible to noise and other corruption; this results in a higher bit-error rate and so higher-order QAM can deliver more data less reliably than lower-order QAM.
1G: First Generation wireless technology
First Generation wireless technology (1G) is the original analog, voice-only cellular telephone standard, developed in the 1980s. One such standard is NMT (Nordic Mobile Telephone), used in Nordic countries, Eastern Europe and Russia. Others include AMPS (Advanced Mobile Phone System) used in the United States, TACS (Total Access Communications System) in the United Kingdom, JTAGS in Japan, C-Netz in West Germany, Radiocom 2000 in France, and RTMI in Italy. Analog cellular service is being phased out in most places worldwide.

1xEV-DO, also known as Evolution Data Optimized (EV-DO), is a third-generation (3G) cellular data technology for GPRS-enabled cellular phones, networks and handheld devices. Its bandwidth is up to 3.1Mbps.
1xEV-DV, also known as Evolution Data/Voice (EV-DV), is a third-generation (3G) cellular data technology for GPRS-enabled cellular phones, networks and handheld devices. Its bandwidth is up to 3.1Mbps.
1xRTT is a cellular data technology for CDMA networks. RTT stands for Radio Transmission Technology. 1xRTT has a theoretical maximum of 144 Kbps of bandwidth, but achieves a practical throughput of only 50 to 70 Kbps in the real world.

2.5G refers to the bridging technologies between second (2G) and third generation (3G) wireless communications. It is a digital communication allowing e-mail and simple Web browsing, in addition to voice. The key technologies include GPRS and WiDEN.

2G: Second Generation Wireless Technology
2G stands for the second generation of mobile wireless communication technology, which uses the digital technologies for the mobile communication. 2G technologies can be divided into TDMA-based (GSM) and CDMA-based standards depending on the type of multiplexing used. It allows slow data communications, but its primary focus is voice.

The 3.5G generally refers to the technologies beyond the well defined 3G wireless/mobile technologies. Currently, HSDPA (High Speed Downlink Packet Access) is considered the primary 3.5G technology which is a software upgrade of WCDMA and provides high-speed broadband wireless access.

3G: Third Generation Wireless Technology
3G stands for the third generation of wireless communication technologies, which support broadband voice, data and multi-media communications over wireless networks. Main 3G standards include CDMA2000, WCDMA, UMTS, etc.

3GPP: The 3rd Generation Partnership Project?
The 3rd Generation Partnership Project (3GPP) is a collaboration agreement that was established in December, 1998. It's a co-operation between ETSI (Europe), ARIB/TTC (Japan), CCSA (China), ATIS (North America) and TTA (South Korea). The scope of 3GPP was to make a globally applicable third generation (3G) mobile phone system specification within the scope of the ITU's IMT-2000 project. 3GPP specifications are based on the evolved GSM specifications, now generally known as the UMTS system.

3GPP2: The 3rd Generation Partnership Project 2
The 3rd Generation Partnership Project 2 (3GPP2) is a collaboration agreement that was established in December, 1998. It's a co-operation between ARIB/TTC (Japan), CCSA (China), TIA (North America) and TTA (South Korea). The scope of 3GPP2 is to make a globally applicable third generation (3G) mobile phone system specification within the scope of the ITU's IMT-2000 project. In practice, 3GPP2 is the standardization group for CDMA2000, the set of 3G standards based on earlier 2G CDMA technology.

3GPP Long Term Evolution (3GPP LTE), also known as Evolved-UMTS Terrestrial Radio Access (E-UTRA or EUTRA) or UMTS Long Term Evolution, is specified in the 3GPP release 8. It is a key 3G technology to ensure the competitiveness of UMTS and provide a high-data-rate, low-latency and packet-optimized system. Besides peak data rates of 100 Mbps in downlink and 50 Mbps in uplink, a significant increase in spectrum efficiency and capacity as well as a significant latency reduction are planned. Commercial aspects like costs for installing and operating the network form also part of the requirements.

3GPS: 3G Service Provider
3GPS (3G Service Provider) is the mobile operator that has 3G license to provide 3G services to customers

3GSM: Third generation GSM network
Third generation GSM (3GSM) is the combination of the 3G nature of the technology and the GSM standard. The core technology that enables the 3GSM is called Universal Mobile Telecommunications System (UMTS).

3-Way Calling
3-Way Calling is a feature in voice communications which allows you to conduct a conference call among three parties.

4G: Fourth generation of wireless communications
4G is the name for the next generation of technology for high-speed wireless communications that is currently in research and development stage. 4G will be designed for new data services and interactive TV through mobile network.

6lowpan: IPv6 over Low power Wireless Personal Area Networks
6lowpan is the IETF working group to define the standards of IPv6 over Low power Wireless Personal Area Networks. 6lowpan is the paragon that is aimed at allowing IPv6 packets to be sent to and received from PANs, more specifically over IEEE802.15.4 (ZigBee) -standard based networks. Likewise, IEEE802.15.4/ZigBee devices provide sensing communication-ability in the wireless domain.

802.11 is a group of wireless specifications developed by the IEEE for wireless local area network (WLAN) communications. It details a wireless interface between devices to manage packet traffic to avoid collisions. Some common specifications include the following: 802.11a, 802.11b, 802.11g, 802.11n, etc.

802.11a is an extension to IEEE 802.11 that applies to wireless LANs and provides up to 54 Mbps in the 5GHz band. 802.11a uses an orthogonal frequency division multiplexing (OFDM) encoding scheme rather than FHSS or DSSS. 802.11a, actually newer than 802.11b, offers significantly more radio channels than the 802.11b and has a shorter range than 802.11g. It isn't compatible with 802.11b.

802.11b, also referred to as 802.11 High Rate or Wi-Fi, is an extension to IEEE 802.11 that applies to wireless LANS and provides 11 Mbps transmission (with a fallback to 5.5, 2 and 1 Mbps) in the 2.4 GHz band. 802.11b uses only DSSS. 802.11b was a ratification to the original 802.11 standard, allowing wireless functionality comparable to Ethernet.

802.11e, an IEEE standard, is the quality-of-service specification over a LAN, in particular, the 802.11 WiFi standard. The standard is considered of critical importance for delay-sensitive applications, such as Voice-over-Wireless IP and Streaming Multimedia. The protocol enhances the IEEE 802.11 Media Access Control (MAC) layer.

802.11g is an extension to IEEE 802.11 which offers wireless transmission over relatively short distances at 20 "€œ 54 Mbps in the 2.4 GHz band. The 802.11g also uses the orthogonal frequency division multiplexing (OFDM) encoding scheme. 802.11g is compatible with older 802.11b.

802.11i, also called Wi-Fi Protected Access 2 (WPA 2), is the standard for WLAN security. WPA 2 supports the 128-bit-and-above Advanced Encryption Standard, along with 802.1x authentication and key management features. It also uses TKIP (Temporal Kye Integrity Protocol) which rotates key periodically to improve WLAN security.

802.11j is the IEEE standard to the 802.11 family of standards for wireless local area networks (WLANs) for 4.9 GHz - 5 GHz frequency use of WLAN systems in Japan.

The 802.11k is the Radio Resource Management standard to provide measurement information for access points and switches to make wireless LANs run more efficiently. It may, for example, better distribute traffic loads across access points or allow dynamic adjustments of transmission power to minimize interference.

802.11n is the IEEE Standard for WLAN enhancements for higher throughput designed to raise effective WLAN throughput to more than 100Mbit/sec. and to cover a range up to 400 meters. IEEE 802.11n technology is also known as Multiple Input, Multiple Output (MIMO).

The 802.11r is the Fast Roaming standard to address maintaining connectivity as a user moves from one access point to another. This is especially important in applications that need low latency and high quality-of-service.

802.11s standard is designed to deal with mesh networking in wireless communication. It is predicted to be ratified in mid-2008.

802.11x refers to a group of evolving wireless local area network (WLAN) standards that are elements of the IEEE 802.11 family of specifications. 802.11x should not be mistaken for any one of its elements because there is no single 802.11x standard. The 802.11 family currently includes six over-the-air modulation techniques that all use the same protocol. The most popular (and prolific) techniques are those defined by the b, a, and g amendments to the original standard; security was originally included and was later enhanced via the 802.11i amendment. 802.11n is another new modulation technique. Other standards in the family (c--f, h, j) are service enhancements and extensions or corrections to previous specifications. 802.11b was the first widely accepted wireless networking standard, followed by 802.11a and 802.11g.

802.15.1 is an IEEE wireless technology standard based on the Bluetooth technology. It is used for short range network monitoring and control applications, which is called wireless personal area network (WPAN).

802.15.3 is an IEEE wireless technology standard that is used for short range network monitoring and control applications, which is called wireless personal area network (WPAN). 802.15.3 is also called UWB.

802.15.4 is an IEEE wireless technology standard that is used for short range network monitoring and control applications, which is called wireless personal area network (WPAN). 802.15.4 is also called Zigbee.

802.16-2004, also known as 802.16d, is an IEEE standard for the fixed wireless broadband (WiMax). IEEE 802.16-2004 product profile utilizes the OFDM 256-FFT (Fast Fourier Transform) system profile. The Fixed WiMAX 802.16-2004 standard supports both time division duplex (TDD) and frequency division duplex (FDD) services -- the latter of which delivers full duplex transmissions on the same signal if desired. Mobile WiMAX will do the same.

802.16-2005, also known as 802.16e, is an IEEE standard addressing mobility of wireless broadband (WiMax). IEEE 802.16-2005 is sometimes called "Mobile WiMAX", after the WiMAX forum for interoperability. 802.16-2005, based on an existing WiMax standard 802.16a, adds WiMax mobility in the 2-to-6GHz-licensed bands.

802.15 is a group of IEEE standards that specifies communications for wireless personal area networks (WPAN) based on the Bluetooth tehnologies. The current technologies included in the IEEE 802.15 family are: 802.15.1 (Bluetooth), 802.15.2 (UWB) and 802.15.4 (ZigBee).

The IEEE 802.16 refers to a group of standards that defines wireless communications between a subscriber site and a core network such as the public telephone network (PSTN) and the Internet. It is called Wireless MAN technology, which is also branded as WiMAX. This wireless broadband access standard provides the missing link for the "last mile" connection in metropolitan area networks where DSL, Cable and other broadband access methods are not available or too expensive.

802.16a is an IEEE wireless communications specification for metropolitan area networks (MANs) as part of a set of standards known as 802.16 or WiMAX. The 802.16a standard was developed for wireless MANs operating between 2 GHz and 11 GHz at data speeds of up to 75 megabits per second (Mbps). 802.16a has been replaced by later standards in the family 802.16d (802.16-2004) and 802.16e (802.16-2005).

802.16d, also known as 802.16-2004, is an IEEE standard for the fixed wireless broadband (WiMax). IEEE 802.16d product profile utilizes the OFDM 256-FFT (Fast Fourier Transform) system profile. The Fixed WiMAX 802.16-2004 standard supports both time division duplex (TDD) and frequency division duplex (FDD) services -- the latter of which delivers full duplex transmission on the same signal if desired.

802.16e, also known as 802.16-2005, is an IEEE standard addressing mobility of wireless broadband (WiMax). IEEE 802.16e is sometimes called "Mobile WiMAX", after the WiMAX forum for interoperability. 802.16e, based on an existing WiMax standard 802.16a, adds WiMax mobility in the 2-to-6 GHz-licensed bands. 802.16e allows for fixed wireless and mobile Non Line of Sight (NLOS) applications primarily by enhancing the OFDMA (Orthogonal Frequency Division Multiple Access).

802.1x is an IEEE authentication specification that allows a client to connect to a wireless access point or wired switch but prevents the client from gaining access to the Internet until it provides credentials, like a user name and password, that are verified by a separate server. In 802.1X, there are three roles: the supplicant (client), authenticator (switch or access point), and authentication server.

802.20 is an IEEE standard of Mobile Broadband Wireless Access (MBWA) by specifying new mobile air interfaces for wireless broadband. 802.20 is a competing standard with 802.16e. 802.16e, based on 802.16a, adds mobility in the 2-to-6 GHz-licensed bands, while 802.20, a brand new standard, aims for operation in licensed bands below 3.5GHz and with a peak data rate of over 1 Mbit/s.

802.22 is an IEEE standard for Wireless Regional Area Networks (WRAN). IEEE 802.22 specifies a cognitive air interface for fixed, point-to-multipoint, wireless regional area networks that operate on unused channels in the VHF/UHF TV bands between 54 and 862 MHz. Signals at these frequencies can propagate 40 km or more from a well-sited base station, depending on terrain.

A2DP: Advanced Audio Distribution Profile
The Advanced Audio Distribution Profile (A2DP) in Bluetooth specifies the protocols and procedures that define the distribution of high quality audio content, in either mono or stereo on Asynchronous Connectionless Link (ACL) channels.

AAS: Adaptive Antenna System
Adaptive Antenna System (AAS), also called Advanced Antenna System, is a technology to enable the network operators to increase the wireless network capacity. In addition, adaptive antenna systems offer the potential of increased spectrum efficiency, extended range of coverage and higher rate of frequency reuse. Adaptive antenna systems consist of multiple antenna elements at the transmitting and/or receiving side of the communication link, whose signals are processed adaptively in order to exploit the spatial dimension of the mobile radio channel. Depending on whether the processing is performed at the transmitter, receiver, or both ends of the communication link, the adaptive antenna technique is defined as multiple-input single-output (MISO), single-input multiple-output (SIMO), or multiple-input multiple-output (MIMO).

A-Band cellular
In the U.S. cellular service industry, A-Band cellular is the alternative carrier to the regional Bell operating company's cellular subsidiaryAbsolute GrantAbsolute Grant (AG), a term used in the mobile wireless channel definition, means the absolute value of the power offset permitted for the power usage.

Absorption Spectrum
Absorption Spectrum is a diagram which shows the wavelengths of electromagnetic radiation absorbed by a material. The material could be a gas, a solute or a solid. An absorption spectrum is, in a sense, the inverse of an emission spectrum.

A-key is a secret number issued to a cellular phone that is used in conjunction with a subscriber's shared secret data information for authentication.

AC: Authentication Center (or AUC)
The Authentication Centre (AC or AUC) is a function to authenticate each SIM card that attempts to connect to the GSM core network (typically when the phone is powered on). Once the authentication is successful, the HLR is allowed to manage the SIM and services described above. An encryption key is also generated that is subsequently used to encrypt all wireless communications (voice, SMS, etc.) between the mobile phone and the GSM core network.

ACCH: Associated Control Channel
Associated Control Channel (ACCH) is the GSM signalling channels associated with a user's traffic channel or dedicated signalling channel. Two ACCH are defined for GSM Circuit Switched operation. These are SACCH (Slow Associated Control Channel) and FACCH (Fast Associated Control Channel). In GPRS packet operation, an ACCH is allocated in conjunction with a PDTCH (Packet Data Traffic Channel) and is termed as PACCH (Packet Associated Control Channel).

ACELP: Algebraic Code Excited Linear Predictive
Algebraic Code Excited Linear Predictive (ACELP) is an algebraic technique used to populate codebooks for CELP speech coders. This technique results in more efficient codebook search algorithms.

ACIR: Adjacent Channel Interference Ratio
Adjacent Channel Interference Ratio (ACIR) is the ratio of wanted power to the interference power from the adjacent channels.

ACLR: Adjacent Channel Leakage Ratio
Adjacent Channel Leakage Ratio (ACLR) is a measure of transmitter performance for WCDMA. It is defined as the ratio of the transmitted power to the power measured after a receiver filter in the adjacent RF channel. This is what was formerly called Adjacent Channel Power Ratio. ACLR is specified in the 3GPP WCDMA standard.

ACPR: Adjacent Channel Power Ratio
Adjacent Channel Power Ratio (ACPR) is a measurement of the amount of interference, or power, in the adjacent frequency channel. ACPR is usually defined as the ratio of the average power in the adjacent frequency channel (or offset) to the average power in the transmitted frequency channel. It is a critical measurement for CDMA transmitters and their components. It describes the amount of distortion generated due to nonlinearities in RF components. The ACPR measurement is not part of the cdmaOne standard.

ACS: Adjacent Channel Selectivity
Adjacent Channel Selectivity (ACS) is a measurement of a receiver's ability to process a desired signal while rejecting a strong signal in an adjacent frequency channel. ACS is defined as the ratio of the receiver filter attenuation on the assigned channel frequency to the receiver filter attenuation on the adjacent channel frequency.

ACTS: Advanced Communications Technology and Services
Advanced Communications Technology and Services (ACTS) is an organization in Europe spearheading the development of 3G technologies in Europe. ACTS succeeded RACE and is focusing on wideband multiple access techniques.

AP: Access point
Access points act as a central transmitter and receiver of WLAN radio signals. Access points used in home or small business networks are generally small, dedicated hardware devices featuring a built-in network adapter, antenna, and radio transmitter. Access points support Wi-Fi wireless communication standards.

Ad hoc
Ad hoc, also known as Ad hoc mode, refers to a short-term wireless network framework created between two or more wireless network adapters without going through an access point. In other words, an Ad hoc network allows computers to "talk" (send data) directly to and from one another. Ad hoc networks are handy for quickly trading files when you have no other way of connecting two or more computers. For an ad hoc network to work, each computer on the network needs a wireless network card installed, and you must set your wireless network cards (installed in each computer on the network) to Ad Hoc mode.

Ad hoc mode
Ad hoc mode refers to a wireless network in which devices can communicate directly with one another without using an AP or a connection to a regular network.

Ad hoc network
Ad hoc network refers to a short-term wireless network framework created between two or more wireless network adapters without going through an access point. Ad hoc networks are handy for quickly trading files when you have no other way of connecting two or more computers.

Adaptive array antennas
Adaptive array antenna is a type of advanced smart antenna technology that continually monitors a received signal and dynamically adapts signal patterns to optimize wireless system performance. The arrays use signal processing algorithms to adapt to user movement, changes in the radio-frequency environment and multi-path and co-channel interference.

Adaptive Equalizer
Adaptive Equalizer is a channel equalizer whose parameters are updated automatically and adaptively during the transmission of data. These equalizers are commonly used in fading channels to improve transmission performance.

Adaptive power control
Adaptive power control is a technique employed by wireless infrastructure systems that lowers the power of a signal in a cell site whenever the site detects that the user's phone is close to the source of the signal. This saves power in the phone, and thus saving battery life too.

ADC: Analog-to-Digital Converter
Analog-to-Digital Converter (ADC, A/D or A to D) is an electronic device that converts continuous signals to discrete digital numbers. The reverse operation is performed by a digital-to-analog converter (DAC). ADC can uniquely represents all analog input values within a specified total input range by a limited number of digital output codes.

Adjacent Channel
Adjacent Channel is a channel or frequency that is directly above or below a specific channel or frequency. First-adjacent is immediately next to another channel, and second-adjacent is two channels away, and so forth. Information on adjacent channels is used in keeping stations from interfering with one another.

Adjacent channel interference
Adjacent channel interference refers to signal impairment to one frequency due to presence of another signal on a nearby frequency.
ADPCM: Adaptive Differential Pulse Code Modulation
Adaptive Differential Pulse Code Modulation(ADPCM) is the process by which analog voice samples are encoded into high-quality digital signals. The first ADPCM standardized by the CCITT is G.721 for 32 kbps. Later came the standards G.726 and G.727 for 40, 32, 24 and 16 kbps. ADPCM is used to send sound on fiber-optic long-distance lines as well as to store sound along with text, images, and code on a CD-ROM.

AGC: Automatic Gain Control
Automatic Gain Control (AGC) is a system which holds the gain and, accordingly, the output of a receiver substantially constant in spite of input-signal amplitude fluctuations.

AGCH: Access Grant Channel
Access Grant Channel(AGCH) is a downlink control channel used in GSM systems to assign mobiles to a Stand-alone Dedicated Control Channel (SDCCH) for initial assignment.

AGPS: Assisted Global Positioning System
Assisted Global Positioning System (AGPS) is a method used for determining mobile station (MS) location in terms of universal latitude and longitude coordinates. This capability has been mandated for wireless carriers in the United States by the Federal Communication Commission, so emergency callers can be easily located in times of crisis. AGPS implies that the mobile not only has GPS hardware and software but that the wireless network is providing the mobile with short assistance messages.

Air Interface
In wireless communications, the air interface is the radio frequency (RF) part of the network that transmits signals between base stations and end-user equipment. The air interface is defined by specifications for a specific format such as GSM, cdma2000, GPRS, or W-CDMA.

AirPort is the Apple's marketing name for its 802.11b wireless networking technology. AirPort, based on IEEE 802.11b, is a local area wireless networking system from Apple Computer and certified as compatible with other 802.11b devices. A later family of products based on the IEEE 802.11g specification is known as AirPort Extreme, offering speeds of up to 54 megabits per second and interoperability with older products.

Airtime is the time elapsed between the start of a call achieved by connecting to your service provider's network and the termination of a call achieved by pressing the end button. Network connection time includes signals received prior to voice transmission, such as busy signals and ringing.

A-key is a secret number issued to a cellular phone that is used in conjunction with a subscriber's shared secret data information for authentication.

AIN: advanced intelligent network
Advanced Intelligent Network (AIN) was Introduced by AT&T Network Systems in 1991 to enable service providers to define, test and introduce new multimedia messaging, PCS and cell routing.

Aliasing is a type of signal distortion that occurs when sampling frequency of a signal is less than the Nyquist rate.

ALOHA is a packet-based radio access protocol developed by the University of Hawaii where every packet sent is acknowledged. Lack of an acknowledgement is an indication of a collision and results in a retransmission.

AM: Amplitude Modulation
Amplitude Modulation (AM) uses amplitude variation in proportion to the amplitude of the modulating signal, and is usually taken as DSB-LC for commercial broadcast transmissions and DSB-SC for multiplexed systems.

AMC: Adaptive Modulation and Coding
Adaptive Modulation and Coding (AMC) is an alternative link adaptation method in 3G mobile wireless communication. AMC provides the flexibility to match the modulation-coding scheme to the average channel conditions for each user. With AMC, the power of the transmitted signal is held constant over a frame interval, and the modulation and coding format is changed to match the current received signal quality or channel conditions.

A-MIMO: Adaptive Multiple Input Multiple Output
Adaptive Multiple Input Multiple Output (A-MIMO or Adaptive MIMO) is a scheme to enhance the MIMO technology by employing adaptive coding and modulation techniques for the purpose of improving channel capacity, diversity, and robustness of wireless communications. In an adaptive MIMO system, the system parameters are jointly optimized to adapt to the changing channel conditions through link adaptation techniques that can track the time-varying characteristics of the wireless channel. The goal is to maximize the resources available in multiple antenna channels by using optimal schemes at all times.

Amplifier, or electronic amplifier, is commonly used in radio and television transmitters and receivers, high-fidelity ("hi-fi") stereo equipment, microcomputers and other electronic digital equipment, and guitar and other instrument amplifiers.

AMPS: Advanced Mobile Phone System Service
Advanced Mobile Phone System (AMPS) Service is the analog mobile phone system standard, introduced in the Americas during the early 1980s. Though analog is no longer considered advanced at all, the relatively seamless cellular switching technology AMPS introduced was what made the original mobile radiotelephone practical, and was considered quite advanced at the time.

AMR: Advanced Multi Rate Codec
Advanced Multi Rate Codec (AMR) is a speech codec standardized by ETSI for GSM. The codec adapts its bit-rate allocation between speech and channel coding, thereby optimizing speech quality in various radio channel conditions. For this reason, 3GPP (under which the next stage GSM speech quality will be realized) has selected the AMR codec as an essential speech codec for the next generation system.

AMS: Adaptive MIMO Switching
Adaptive MIMO Switching (AMS) is a scheme to switch between multiple MIMO modes to maximize spectral efficiency with no reduction in coverage area. In an adaptive MIMO switching system, the system parameters are jointly optimized to adapt to the changing channel conditions through link adaptation techniques that can track the time-varying characteristics of the wireless channel. The goal is to maximize the resources available in multiple antenna channels by using optimal schemes at all times.

AMTA: American Mobile Telecommunications Association
American Mobile Telecommunications Association (AMTA) is a trade group, based in Washington, D.C., representing specialized mobile radio operators.

Analog System
Analog system uses an analog transmission method to send voice, video and data-using analog signals, such as electricity or sound waves, that are continuously variable rather than discreet units as in digital transmissions. Mobile analog systems include AMPS, NMT and ETACS.

Analog Transmission
Analog Transmission refers to signals propagated through the medium as continuously varying electromagnetic waves.

Angle diversity
Angle diversity is a technique using multiple antenna beams to receive multipath signals arriving at different angles.

Antenna is a device which radiates and/or receives radio signals.

Antenna beamwidth
Antenna beamwidth, also known as the half-power beamwidth, is the angle of an antenna pattern or beam over which the relative power is at or above 50% of the peak power.
Antenna directivity
Antenna directivity, also known as antenna gain, is the relative gain of the main beam of an antenna pattern to a reference antenna, usually an isotropic or standard dipole.

Antenna gain
Antenna gain, also known as antenna directivity, is the relative gain of the main beam of an antenna pattern to a reference antenna, usually an isotropic or standard dipole.

APC: Automatic Power Control
Automatic Power Control (APC) is a technique of measuring the performance of a radio channel and adjusting the power of the transmitter to a level appropriate for link characteristics.

APCM: Adaptive Pulse Code Modulation
Adaptive Pulse Code Modulation (APCM) is a technique used to share occupied bandwidth among a maximum number of subscribers during peak times by reducing the signal sampling rates of each subscriber.

APS: Application Support
Application Support (APS) is a sublayer in the ZigBee protocol stack. The responsibilities of the APS sub-layer include maintaining tables for binding to match two devices together based on their services and their needs, and forwarding messages between bound devices. The APS sub-layer is also responsible to determine the responsibilities of the ZDO, to initiate/respond to binding requests, and to establish a secure relationship between network devices.

ARCH: Access Response Channel
Access Response Channel (ARCH), a logic sub-channel of SPACH specified in IS-136, carries wireless system responces from the cell site to the user equipment.
ARIB: Association of Radio Industries and Businesses
Association of Radio Industries and Businesses (ARIB) is the Japanese standards-setting organization.

ASN: Access Service Network
Access Service Network (CSN), a concept in the mobile WiMAX network, provides full mobility, seamless handoffs, Quality of Service, security and subscriber/connection/resource management.

ARDIS: Advanced Radio Data Information Service
Advanced Radio Data Information Service (ARDIS) is a wireless two-way data network jointly owned and operated by Motorola and IBM.

ARFCN: Absolute Radio Frequency Channel Numbers
Absolute Radio Frequency Channel Numbers (ARFCN) is a channel numbering scheme used to identify specific RF channels in a GSM radio system.

ARQ: Automatic Repeat Request
Automatic Repeat Request (ARQ) is a communication protocol in which the receiving device detects errors and requests retransmissions. When the receiver detects an error in a packet, it automatically requests the transmitter to resend the packet. This process is repeated until the packet is error free or the error continues beyond a predetermined number of transmissions. ARQ is sometimes used with Global System for Mobile (GSM) communication to guarantee data integrity.

Attenuation refers to decreasing in signal magnitude between two points. These points may be along a radio path, transmission line or other devices.

Attenuator is a device specifically designed to decrease the magnitude of a signal transmitted through it.

AUC: Authentication Center
The Authentication Center (AUC) is a device, usually located in the HLR of a GSM system, to authenticate each SIM card that attempts to connect to the GSM core network (typically when the phone is powered on). Once the authentication is successful, the HLR is allowed to manage the SIM and services described above. An encryption key is also generated that is subsequently used to encrypt all wireless communications (voice, SMS, etc.) between the mobile phone and the GSM core network.

Average power
Average power is the peak power averaged over time and is usually applied to pulsed systems where the carrier power is switched on and off.
AWGN: Additive White Gaussian Noise
Additive White Gaussian Noise (AWGN) is the statistically random radio noise characterized by a wide frequency range with regards to a signal in a communications channel.

In wireless technology, backhaul refers to transporting voice and data traffic from a cell site to the switch.

Backscattering is radio wave propagation in which the direction of the incident and scattered waves, resolved along a reference direction (usually horizontal) are oppositely directed. A signal received by backscattering is often referred to as "backscatter."

Band in telecommunication refers to the following definitions: 1. The range of frequencies between two defined limits which are used for a specific purpose. 2. One of the geopolitical boundaries established to define a WATS (wide-area telephone service) serving area.

Band Elimination Filter
Band Elimination Filter is an electrical device which blinds a receiving unit from recognizing a specific range of frequencies.

Band Pass Filter
Band Pass Filter is a radio wave filter with a specific range of frequencies in which it is designed to pass, while rejects frequencies outside the pass-band. Resistor-inductor-capacitor circuit is an example of Band Pass Filter.

Bandwidth is the portion of the frequency spectrum required to transmit desired information. Each radio channel has a center frequency and additional frequencies above and below this carrier frequency which is used to carry the transmitted information. The range of frequencies from the lowest to the highest used is called the bandwidth.

Baseband is the transmission of a digital or analog signal signaling at its original frequencies and in its original form. It should not be changed by modulation.

Baseband layer
Baseband layer, also known as baseband packet, is a physical layer protocol in the Bluetooth protocol stack. The Baseband in the Bluetooth manages physical channels and links apart from other services like error correction, data whitening, hop selection and Bluetooth security. The Baseband layer lies on top of the Bluetooth radio layer in the bluetooth stack. The baseband protocol is implemented as a Link Controller, which works with the link manager for carrying out link level routines like link connection and power control. The baseband also manages asynchronous and synchronous links, handles packets and does paging and inquiry to access and inquire Bluetooth devices in the area.

Baseband signal
Baseband signal is a signal with frequency content centered around DC. Typically it is the modulating signal for an RF carrier.

B-Band cellular
In the U.S. cellular service industry, B-Band cellular refers to the regional Bell operating company's cellular subsidiary.

BCCH: Broadcast Control Channel
Broadcast Control Channel (BCCH) is a downlink-point-to-multipoint logical channel in GSM and cdma2000 systems used to send identification and organization information about common control channels and cell services.

B-CDMA: broadband code division multiple access
Broadband code division multiple access (B-CDMA) is designed to correct many of the inherent short-falls of IS-95 (narrowband CDMA) and other digital narrowband technologies. In addition, it is being designed as a long-term solution to both voice and data wireless needs -- fixed and mobile. Some of the technical aspects of the B-CDMA air interface are related to its propagation characteristics.

BCH code:Bose-Chaudhuri-Hocquenghem Code
Bose-Chaudhuri-Hocquenghem (BCH) Code is a family of powerful cyclic block forward error correction codes used in the transmission of data.

BCH: Broadcast Channels
Broadcast Channels (BCH) are a group downlink point to multipoint logical channels used by mobiles to synchronize to and receive information necessary to access a cell in GSM, cdma2000, and WCDMA systems.

Bent pipe technology
Bent pipe technology is a satellite technology to transmit calls from one point on Earth to a satellite and back down to another point.

BE Service: Best Effort Service
Best Effort (BE) Service is one of the five QOS service types defined in the IEEE 802.16 WiMAX. The 802.16 protocol supports five types of QoS: UGS (Unsolicited grant service), rtPS (Real time polling Service), ertPS (Extended Real-time POLLING SERVICE), nrtPS (Non-real-time polling service and BE (Best effort service). The aim of the Best Effort (BE) service is to provide efficient service to best effort traffic.

BGCF: Breakout Gateway Control Function
Breakout Gateway Control Function (BGCF), a component in the IP Multimedia Subsystem (IMS), controls call transfers to and from the public switched telephone network (PSTN).

Big LEO refers to a low-earth orbit satellite system that will offer voice and data services, e.g., Iridium, Globalstar. Orbits, typically a few thousand kilometers high, that are intermediate in size between little LEO (low Earth orbit) and geosynchronous orbits. The term is applied especially to some of the latest generation of communication satellites that support communications using small handheld sets.

BlackBerry is a two-way wireless device, made by Waterloo, that allows users to check e-mail and voice mail (translated into text), as well as to page other users via a wireless network service. Also known as a RIM device, it has a miniature qwerty keyboard for users to type their messages. It uses the SMS protocol. BlackBerry users must subscribe to a wireless service that allows for data transmission.

BLER: Block Error Rate
Block Error Rate (BLER) is a ratio of the number of erroneous blocks to the total number of blocks received on a digital circuit. Block error rate (BLER) is used for W-CDMA performance requirements tests (demodulation tests in multipath conditions, etc). BLER is measured after channel de-interleaving and decoding by evaluating the Cyclic Redundancy Check (CRC) on each transport block.

Block code
Block code is a family of codes having a one-to-one mapping between k-symbol source words and n-symbol code words.

Blocking probability
Blocking probability is the statistical probability that a telephone connection cannot be established due to insufficient transmission resources in the network. Usually expressed as a percentage or decimal equivalent of calls blocked by network congestion during the busy hour.

bluesnarf (bluesnarfing)
Bluesnarfing is the theft of information from a wireless device through a Bluetooth connection.

Bluetooth, defined in IEEE 802.15, is for wireless personal area networks (WPANs), which has characters such as short-range, low power, low cost, small networks and communication of devices within a Personal Operating Space. Bluetooth is for wireless transmission between a wide variety of devices such as PCs, cordless phone, headsets and PDAs within 10-meter range.

BPSK: Binary Phase Shift Keying
Binary Phase Shift Keying (BPSK) is a type of phase modulation using 2 distinct carrier phases to signal ones and zeros. BPSK is the simplest form of PSK. It uses two phases which are separated by 180A° and so can also be termed 2-PSK. It does not particularly matter exactly where the constellation points are positioned, and, in this figure, they are shown on the real axis, at 0A° and 180A°. This modulation is the most robust of all the PSKs since it takes serious distortion to make the demodulator reach an incorrect decision. It is, however, only able to modulate at 1bit/symbol (as seen in the figure) and so is unsuitable for high data-rate applications.

BREW: Binary Runtime Environment for Wireless
Binary Runtime Environment for Wireless (BREW) is an open system created by Qualcomm for delivering over-the-air applications and data. The hottest use for BREW to date has been downloadable games

Broadband refers to telecommunication that provides multiple channels of data over a single communications medium, typically using some form of frequency or wave division multiplexing.

Broadband PCS
Broadband PCS is the personal communications services created in the A- through F-Block auctions and used for voice and data. Mobile broadband PCS services include both voice and advanced two-way data capabilities that are generally available on small, mobile multifunction devices.

Broadband Wireless Access
Broadband wireless access is a technology aimed at providing wireless access to data networks, with high data rates. According to 802.16-2004 standard, broadband means "having instantaneous bandwidth greater than around 1 MHz and supporting data rates greater than about 1.5 Mbit/s". From the point of view of connectivity, broadband wireless access is equivalent to broadband wired access, such as ADSL or cable modems. It is planned to be used in the next few years and is thought to be used up to 40 miles away.

BS: Base Station
Base station (BS), also called cell site, is the local cellular tower and radio antenna (including the radios, controller, switch interconnect, etc.) that handles communication with mobile users in a particular area or cell. A cellular network is made up of many cell sites or base stations, all connected back to the switch via landline or microwave.

BSC: Base Station Controller
Base Station Controller (BSC) is a device and software associated with a base station that permits it to register mobile phones in the cell, assign control and traffic channels, perform handoff and process call setup and termination.

BSIC: Base Station Identity Code
Base Station Identity Code (BSIC) is a unique code contained in messages on the broadcast channels of a cell or base station that uniquely identifies the base station.

BSS: Base Station Subsystem
The Base Station Subsystem (BSS) is the section of a GSM network which is responsible for handling traffic and signalling between a mobile phone and the Network Switching Subsystem. The BSS carries out transcoding of speech channels, allocation of radio channels to mobile phones, paging, quality management of transmission and reception over the Air Interface and many other tasks related to the radio network.

BSSID: Basic Service Set Identifier
BSSID refers to the MAC address of the Station (STA) in an Access Point (AP) in an infrastructure mode BSS defined by the IEEE 802.11-1999 Wireless Lan specification. This field uniquely identifies each BSS. In an IBSS, the BSSID is a locally administered IEEE MAC address generated from a 46-bit random number. The individual/group bit of the address is set to 0. The universal/local bit of the address is set to 1.

BT: Bandwidth Time Product
Bandwidth Time Product (BT) is the result obtained by multiplying the system bandwidth by the signal duration. As a general rule, the system bandwidth must be approximately equal to the reciprocal of the signal duration to produce an output signal of the same general form as the input, i.e., BT»1.

BTA: Basic Trading Area
Basic Trading Area (BTA) refers to the area or "footprint" in which an entity is licensed to transmit their frequencies. BTAs were established by Rand McNally and are defined as county lines. Rand McNally licensed their mapping data to the FCC for ease of designation for site licenses. BTAs are about the size of a cellular MSA and cross state lines in some instances. BTAs are grouped into larger areas called MTAs.

BTC: Block Turbo Code
Block Turbo Code (BTC) is a type of turbo codes. BTC is a product code obtained from the concatenation of either two extended or two expurgated Bose-Chaudhuri-Hocquenghem (BCH) codes. Block Turbo-codes (BTC) are promising forward error correction (FEC) codes providing close-to-optimal coding gain for rather high coding rate (R > 0.7) and less subject to an error floor than Convolution Turbo Codes (CTC).

BTS: Base Transceiver Station
Base Transceiver Station (BTS) effects radio communications with mobile stations (MS) via its respective radio access system and transmits/receives signals to/from connected radio network controllers (RNC) located along transmission routes.

C/I: Carrier-to-Interference ratio
Carrier-to-Interference ratio (C/I) is the ratio of power in an RF carrier to the interference power in the channel.

C/N: Carrier-to-Noise ratio
Carrier-to-Noise ratio (C/N) is the ratio of power in an RF carrier to the noise power in the channel. Carrier-to-Noise ratio indicates the difference in amplitude between the desired radio frequency (RF) carrier and the noise in a portion of the spectrum.

CAI: Common Air Interface
Common Air Interface (CAI) is a set of open standards describing the physical and logical characteristics of a link between a base station and a mobile station. These standards are used by infrastructure and handset manufactures to design and build equipment that is capable of interoperating with each other's systems.

Call Diversion
Call Diversion is the feature used to divert incoming calls on a mobile phone to any other telephone or to a Mailbox/Combox on a GSM system.

CAMEL: Customized Application for Mobile Network Enhanced Logic
Customized Application for Mobile Network Enhanced Logic (CAMEL) refers to a set of 3rd Generation APIs based on ETSI recommendation TS 129 078 (V3.3.0). CAMEL finds widespread applicability in developing applications for next generation networks converging Phase 2+ GSM/UMTS. CAMEL allows roaming subscribers access to their full portfolio of IN services. CAMEL GSM phase 2+ connects the home and visited mobile networks to various Intelligent Network (IN) platforms used throughout national networks to provide features such as Pre-Paid Calling, personal Numbering and more complex location dependent services. As a result, CAMEL is a relatively inexpensive method of allowing telecom operators to add new services to the existing network infrastructure.

CAP CODE is a pager's unique electronic identification number.

Carrier means the continuous frequency capable of being modulated or impressed with a second signal.

Carrier frequency
Carrier Frequency refers to the nominal frequency of a carrier wave, the frequency of the unmodulated electrical wave at the output of an amplitude modulated, the center frequency of a frequency modulation signal, frequency modulated, or phase modulated transmitter of the output of a transmitter when the modulation is zero.

Carrier recovery
Carrier recovery is a technique for extracting the RF carrier from a modulated signal so that it can be reinserted and used to recover the modulating signal.

CBC: Cell Broadcast Center Cell Broadcast Center (CBC) is the functional entity within the mobile network that is responsible for the generation of cell broadcast information.

CBCH: Cell Broadcast Channel
Cell Broadcast Channel (CBCH) is a downlink point-to-multipoint logical channel in a GSM system used to broadcast user information from a service center to mobile stations listening in a given cell area.

Chase Combining
Chase Combining (CC), also known as Convolution Code, is one of the two fundamental forms of Hybrid ARQ (HARQ). The other one is an incremental redundancy (IR). In Chase combining, each retransmission repeats the first transmission or part of it. While Chase combining is sufficient to make AMC robust, IR offers the potential for better performance with high initial code rates and FER operating points at the cost of additional memory and decoding complexity.

CCDF: Complementary Cumulative Distribution Function
Complementary Cumulative Distribution Function (CCDF) is a method used to characterize the peak power statistics of a digitally modulated signal. The CCDF curve can be used to determine design parameters for CDMA systems (such as the amount of back-off to run in a power amplifier).

CCH: Control Channel
Control Channel (CCH) refers the channels that transmit signaling and control information between the network and the mobile stations.

CCI: Co-Channel Interference
Co-channel interference (CCI) refers to interference from 2 different radio stations on the same frequency. CCI is one of the major limitations in cellular and PCS wireless telephone networks. In the case of TDMA networks, such as GSM/GPRS or NADC (otherwise known as "IS-136"), the co-channel interference is mainly caused by the spectrum allocated for the system being reused multiple times ("frequency reuse"). Co-channel interference, when not minimized, decreases the ratio of carrier to interference powers (C/I) at the periphery of cells, causing diminished system capacity, more frequent handoffs, and dropped calls.

CCITT: International Telegraph and Telephone Consultative Committee
CCITT is the abreviation of the International Telegraph and Telephone Consultative Committee in France. CCITT is standards body based in Geneva that publishes "recommendations" on standards used throughout the world communication industry.

CCM: Counter mode with Cipher-block chaining Message authentication code
Counter mode with Cipher-block chaining Message authentication code (CCM) is an encryption protocol in the 802.11i standard. The CCM protocol (CCMP) is based upon the CCM mode of the AES encryption algorithm and utilizes 128-bit keys, with a 48-bit initialization vector (IV) for replay detection.

CCMP: Counter mode with Cipher-block chaining Message authentication code
Protocol Counter mode with Cipher-block chaining Message authentication code Protocol(CCMP) is an encryption protocol in the 802.11i standard. The CCMP is based upon the CCM mode of the AES encryption algorithm and utilizes 128-bit keys, with a 48-bit initialization vector (IV) for replay detection.

CCSA: China Communications Standards Association
China Communications Standards Association (CCSA) is a P. R. China gorvenment sponsored organization to establish a nationally unified standards in the communication technologies. With the approval of the Ministry of Information Industries (MII) and Standardization Administration of China and the Civil Affairs Ministry, China Communications Standards Associatio (CCSA) was founded in December 18, 2002.

CCTrCH: Coded Composite Transport Channel
Coded Composite Transport Channel (CCTrCH), a technology in the UMTS physical layer, is the connection between Transport Channel and Physical Channel which results in a data stream from encoding and multiplexing of one or several transport channels.

CDF: Cumulative Distribution Function
Cumulative Distribution Function (CDF) describes the probability distribution of a real-valued random variable, X. The Kolmogorov-Smirnov test is based on cumulative distribution functions and can be used to test to see whether two empirical distributions are different or whether an empirical distribution is different from an ideal distribution.

CDG: CDMA Development Group
CDMA Development Group (CDG) is an international consortium of companies who have joined together to lead the adoption and evolution of 3G CDMA wireless systems around the world. The CDG is comprised of CDMA service providers and manufacturers, application developers and content providers. By working together, the members help to ensure interoperability among systems, while expediting the availability of 3G CDMA technology to consumers.

CDM: Code Division Multiplexing
Code Division Multiplexing or Code Division Multiplex (CDM) is a technique in which each channel transmits its bits as a coded channel-specific sequence of pulses. This coded transmission typically is accomplished by transmitting a unique time-dependent series of short pulses, which are placed within chip times within the larger bit time. All channels, each with a different code, can be transmitted on the same fiber and asynchronously demultiplxed. Other widely used multiple access techniques are Time Division Multiple Access (TDMA) and Frequency Division Multiple Access (FDMA).

CDMA: Code Division Multiple Access
Code Division Multiple Access (CDMA) is a second generation (2G) cellular technology defined by Qualcomm in IS-95 and IS-2000. Other widely used multiple access techniques for cellular are Time Division Multiple Access (TDMA) and Frequency Division Multiple Access (FDMA). CDMA technologies are evolving into CDMA2000 to meet the challenges. CDMA2000 is the 3rd Generation solution based on IS-95.

Code Division Multiple Access 2000 (CDMA2000 or CDMA-2000) is the 3rd Generation solution based on CDMA IS-95, which supports 3G services as defined by the ITU 3G standards IMT-2000. CDMA2000 defines both an air interface and a core network. CDMA2000 has already been implemented as an evolutionary step from cdmaOne as CDMA2000 provides full backward compatibility with IS-95B.

cdmaOne is the commercial name for a CDMA (Code Division Multiple Access) system defined by the consortium including Qualcomm, AT&T Wireless and Motorola. The IS-95 standard is part of cdmaOne as the air interface.

CDP: Code Domain Power
Code Domain Power (CDP) is a measurement of the power contained in each Walsh coded channel in CDMA signals. The CDP measurement is beneficial in troubleshooting CDMA transmitter designs.

E.214 is a telephone numbering plan used for delivering mobility management related messages in GSM networks. The E.214 number derived from the IMSI E.214 numbers are composed of two parts. The first, the E.164 part, is made up of a country code followed by the network code. The second part of the number is made from the MSIN part of the IMSI which identifies an individual subscriber. For more details on the derivation of the E.214 number from the IMSI, see the article about the IMSI.
EA: Economic Area
Economic Area (EA) is a geographic area over which a WCS operator is licensed to provide service. EAs are a group of counties in metropolitan areas having common financial, commercial and economic ties and were first used to license. WCS service in the late '90s. EAs are about the size of a cellular MSA and cross state lines in some instances. EAs are used by the FCC to define areas of economic interest and are grouped into larger areas called REAGs.

E-AGCH: E-DCH Absolute Grant Channel
E-DCH Absolute Grant Channel(E-AGCH) is one of the five Enhanced Dedicated Channels (E-DCH), which provides an absolute power level above the level for the DPDCH (associated with a DCH) that the UE should adopt. E-AGCH tell a UE how to regulate its transmit power level.
EAP: Extensible Authentication Protocol
Extensible Authentication Protocol (EAP) is a general layer 2 protocol for authentication EAP supports multiple authentication mechanisms. EAP does not select a specific authentication mechanism at Link Control Phase, but rather postpones this until the Authentication Phase. This allows the authenticator to request more information before determining the specific authentication mechanism. This also permits the use of a "back-end" server which actually implements the various mechanisms while the PPP authenticator merely passes through the authentication exchange.

EAPoW: Extensible Authentication Protocol over Wireless Extensible Authentication Protocol over Wireless (EAPoW) is a term used when EAPoL messages are encapsulated over 802.11 wireless frames.
EAP-TLS: Extensible Authentication Protocol with Transport Layer Security
Extensible Authentication Protocol with Transport Layer Security (EAP-TLS) enables authenticaton between WLAN devices using certificates.

Eb/N0: Bit Energy-to-Noise Density
Bit Energy-to-Noise Density (Eb/N0) is the ratio of bit energy to noise density. This value is used to specify the lower limit of operation in most digital communications systems and is also used to measure radio channel performance.
EDACS: Enhanced Digital Access Communication System
Enhanced Digital Access Communication System (EDACS) is a radio communications protocol and product family invented in the General Electric Corporation, in the mid-1980s. EDACS was developed in competition with Motorola's Smartnet trunking system. It claimed, and continues to hold, significant market shares.

E-DCH: Enhanced Dedicated Channel
Enhanced Dedicated Channel (E-DCH) is a transport uplink channel used in the 3G technologies (such as HSUPA) to improve capacity and data throughput and reduce the delays in dedicated channels in the uplink. The maximum theoretical uplink data rate that can be achieved is 5.6 Mbps. As with HSDPA, E-DCH relies on improvements implemented both in the PHY and the MAC layer. The definition of the E-DCH introduces five new physical layer channels: E-DPDCH, E-DPCCH, E-AGCH, E-RGCH and E-HICH.
EDGE: Enhanced Data rates for GSM Evolution Enhanced Data Rates for Global Evolution (EDGE), also known as Enhanced GPRS (EGPRS), is a digital mobile phone technology which acts as a bolt-on enhancement to 2G and 2.5G General Packet Radio Service (GPRS) networks. This technology works in GSM networks. EDGE is a superset to GPRS and can function on any network with GPRS deployed on it, provided the carrier implements the necessary upgrades. EDGE uses the same spectrum allocated for GSM900, GSM1800 and GSM1900 operations.

E-DPCCH: E-DCH Dedicated Physical Control Channel E-DCH Dedicated Physical Control Channel (E-DPCCH) is one of the five Enhanced Dedicated Channels (E-DCH), which controls channels associated with the E-DPDCH providing information to the Node-B on how to decode the E-DPDCH.
E-DPDCH: E-DCH Dedicated Physical Data Control Channel
E-DCH Dedicated Physical Data Control Channel (E-DPDCH) is one of the five Enhanced Dedicated Channels (E-DCH), which is the physical channel used by E-DCH for the transmission of user data.
EESM: Exponential Effective SIR Mapping
Exponential Effective SIR Mapping (EESM) is a method to estimate demodulator performance in a channel with frequency selective signal and/or noise. In a sense, the EESM is a channel-dependent function that maps power level and MCS level to SINR values in the Additive White Gaussian Noise (AWGN) channel domain. This allows using this mapping along with AWGN assumptions (such as effect of an increase in power, CINR/MCS threshold tables) in order to predict the effect of MCS and boosting modification. The EESM method has been shown to yield an accurate estimation of the AWGN-equivalent SINR for frequency selective channels.

EFR: Enhanced Full Rate
Enhanced Full Rate is a voice coding algorithm applied in PCS-1900 systems (and now in GSM-900 as well, first system installed in Hong Kong).
EGPRS: Enhanced General Packet Radio Service
Enhanced General Packet Radio Service (EGPRS), also known as Enhanced Data Rates for Global Evolution (EDGE), is a digital mobile phone technology. As an enhancement to GPRS, EGPRS improves spectral efficiency and data rates by adding new modulation and coding schemes. EGPRS uses the modulation technique 8PSK (8 Phase Shift Keying) to increase the achievable user data rate.

EGPRS: Enhanced General Packet Radio Service
Enhanced General Packet Radio Service (EGPRS) is an enhancement to GPRS that improves spectral efficiency and data rates by adding new modulation and coding schemes.
E-GSM: Extended Global System for Mobile
EGSM is an extension to the GSM900 spectrum. EGSM spectrum is 880-890 MHz paired with 925-935 MHz, which is just below the original GSM 900 band. EGSM is a small radio frequency band used in Europe to provide added network capacity for GSM 900 networks. The additional 10Mhz provides an additional 50 channels.

EHF: Extremely High Frequency Extremely High Frequency (EHF) is the RF spectrum between 30 GHz and 300 GHz.
E-HICH: E-DCH HARQ Acknowledgement Indicator Channel
E-DCH HARQ Acknowledgement Indicator Channel (E-HIGH) is one of the five Enhanced Dedicated Channels (E-DCH), which is used by Node-B to send HARQ ACK/NACK messages back to the UE.

EIA: Electronic Industry Association
Electronic Industry Association (EIA) is a trade association and standards setting organization in the USA.
EIR: Equipment Identity Register
Equipment Identity Register (EIR) is a database used by GSM and other second generation wireless systems used to identify the customer devices permitted to access the network. A device is usually placed in the EIR once its operation has been certified for the infrastructure in a laboratory or validation facility.

EIRP: Effective Isotropic Radiated Power
Effective Isotropic Radiated Power (EIRP), also known as Equivalent Isotropically Radiated Power, is the amount of power that would have to be emitted by an isotropic antenna (that evenly distributes power in all directions and is a theoretical construct) to produce the peak power density observed in the direction of maximum antenna gain. EIRP can take into account the losses in transmission line and connectors and includes the gain of the antenna. The EIRP is often stated in terms of decibels over a reference power level, that would be the power emitted by an isotropic radiator with an equivalent signal strength. The EIRP allows making comparisons between different emitters regardless of type, size or form. From the EIRP, and with knowledge of a real antenna's gain, it is possible to calculate real power and field strength values.
Electromagnetic Spectrum
Electromagnetic Spectrum refers to the full range of electromagnetic frequencies, which include Radio Frequency (RF).

EMC: Electro Magnetic Compatibility
Electro Magnetic Compatibility (EMC) is the ability of different items of electrical equipment to work together without suffering the effects of interference. Equipment should operate without interfering with broadcast and communications signals and be immune to normal levels of such signals. For a given environment, e.g. on the factory floor, EMC implies that equipment should not generate unacceptable levels of interference which affect the performance of other products designed to operate in an industrial environment. Also, equipment should have sufficient immunity to electrical interference, such that the equipment continues to operate in an acceptable manner.
EMI: Electromagnetic Interference
Electromagnetic Interference (EMI) is the interference by electromagnetic signals that can cause reduced data integrity and increased error rates on transmission channels.

EMS: Enhanced Messaging Service
Enhanced Messaging Service (EMS) utilizes SMS but adds the ability to incorporate simple graphics, pictures, animations and sound. With this, the user can add an actual emotion to his/her message. Give someone a full birthday wish (with the text, the actual song, and a graphic of a birthday cake).
Encoder is a converter used to create a specific addressed message.

EPOC, now called Symbian OS, is an operating system optimized for mobile phone/PDA uses. It was developed by Symbian which is a joint company of Psion, Nokia, Ericsson, Motorola and Matsushita (Panasonic). EPOC turns voice-oriented handsets into Mediaphones and Wireless Information Devices. EPOC places a lighter load on the processor compared to present PDA operating systems and thus has the capacity to enhance the multimedia capacity of mobile phones.
Equalization is a technique used to compensate for communications channel distortions. This technique is often used in the mobile wireless communications.

E-RGCH: E-DCH Relative Grant Channel
E-DCH Relative Grant Channel(E-RGCH) is one of the five Enhanced Dedicated Channels (E-DCH), which indicates to the UE whether to increase, decrease or keep unchanged the transmit power level of the E-DCH.
ERMES: European radio messaging system
European radio messaging system is a paging system used in Europe and other parts of the world.

Error correction
Error correction is the process of correcting errors in data transmitted over a radio channel using forward error correction (FEC) techniques.
Error distribution Error distribution describes how errors in a communications channel are distributed. Typical distributions are Gaussian (random) and Raleigh (bursty).

Error probability
Error probability is a computation of the likelihood of an error involving the Probability Density Function (PDF).
Error vector The error vector is the vector difference between a reference signal and a measured signal and is a complex quantity containing a magnitude and phase component.

ertPS: Extended Real-Time Polling Service
Extended Real-Time Polling Service (ertPS) is one of the five QOS service types defined in the IEEE 802.16 WiMAX. The 802.16 protocol supports five types of QoS -- UGS (Unsolicited grant service), rtPS (Real time polling Service), ertPS (Extended Real-time POLLING SERVICE), nrtPS (Non-real-time polling service and BE (Best effort service). ertPS is a scheduling mechanism that builds on the efficiency of both UGS and rtPS. The ertPS is designed for realtime traffic with variable data rate (such as VOIP service with silence suppression) over the WiMAX network.
ESMR: enhanced specialized mobile radio
Enhanced specialized mobile radio (ESMR) is a digital SMR network, which provides dispatch, voice, messaging and data services.

ESN: Electronic Serial Number
Electronic Serial Number (ESN) is a unique unchangeable number that is built into the mobile phone and is transmitted by the phone as a means of identifying itself within the system. Each mobile phone is assigned a unique ESN.
ESS: Extended Service Set
Extended Service Set (ESS) is a set of two or more BSSes working together to form a single network.

ESSID: Extended Service Set Identifier
Extended Service Set ID (ESSID) is the identifying name of a wireless network -- strictly, it is the identifying name of a wireless access point. It allows one wireless network to be clearly distinguishable from another. ESSID is one type of SSID (the other being BSSID).
ETACS: Extended Total Access Communications System
Extended Total Access Communications System (ETACS or E-TAGS) is the analog mobile phone network developed in the UK and available in Europe and Asia. ETAGS is the Extension of TACS through the allocation of additional radio channels.

E-TAGS: Extended Total Access Communication System
E-TAGS is Extension of the TACS (Total Access Communications System) system through the allocation of additional radio channels.
E-TDMA: Enhanced or exended TDMA
Enhanced or exended TDMA (E-TDMA) is an enhanced version of TDMA which will not only serve cellular, but could provide PCN-like services within current spectrum allocations.

E-UTRA: Evolved-UMTS Terrestrial Radio Access
Evolved-UMTS Terrestrial Radio Access (E-UTRA or EUTRA), also known as UMTS Long Term Evolution (3GPP LTE) or Evolved UMTS Terrestrial Radio Access Network (EUTRAN), is specified in the 3GPP release 8. It is a key 3G technology to ensure the competitiveness of UMTS and provide a high-data-rate, low-latency and packet-optimized system. Besides peak data rates of 100 Mbps in downlink and 50 Mbps in uplink, a significant increase in spectrum efficiency and capacity as well as a significant latency reduction are planned. Commercial aspects like costs for installing and operating the network form also part of the requirements.
ETSI: European Telecommunications Standard Institute
European Telecommunications Standard Institute (ETSI) is an independent, non-profit organization, whose mission is to produce telecommunications standards for today and for the future. Based in France, ETSI is officially responsible for standardization of Information and Communication Technologies (ICT) within Europe. These technologies include telecommunications, broadcasting and related areas such as intelligent transportation and medical electronics.

EVDO: Evolution Data Only/Evolution Data Optimized
Evolution Data Only/Evolution Data Optimized (EVDO or 1xEV-DO) is a high-speed network protocol used for wireless Internet data communications. The EVDO protocol supports asymmetric communications, allocating a majority of this bandwidth to downloads. EVDO is based on the 1xRTT standard, providing data transmission speeds wirelessly up to 3.1Mbps. It is for always-on mobile packet data and voice for GPRS-enabled cellular phones, networks and handheld devices.
EV-DV: EVolution for Data and Voice
EVolution for Data and Voice (EV-DV, EVDV or 1xEV-DV) is the technology that provides integrated voice and simultaneous high-speed packet data multimedia services at high speeds. 1xEV-DV is backward compatible to IS-95A/B and CDMA2000 1X and enables a simple migration to 1xEV-DV from 1X networks while preserving existing services offered by operators, including voice and data services on the same carrier, and simultaneous voice and data.

EVM: Error Vector Magnitude
Error Vector Magnitude (EVM) is a modulation quality metric widely used in digital RF communications systems. It is the root-mean-square (rms) value of the error vector over time at the instants of symbol clock transitions. Used properly, EVM and related measurements can pinpoint exactly the type of degradations present in a signal and can even help identify their sources.
Eye diagram
Eye diagram is a superposition of segments of a received PAM signal displayed on an oscilloscope or similar instrument. The eye diagram is used to assess impairments in the radio channel.

FACCH: Fast Associated Control Channel
Fast Associated Control Channel (FACCH) is the channel derived by preempting information in a traffic channel. It is used to send handoff and similar messages.
Fading is the variation in signal strength from its normal value. Fading is normally negative and can be either fast or slow. It is normally characterized by the distribution of fades, Gaussian, Rician, or Rayleigh.

FASS: Fast Access Station Switching
Fast Access Station Switching (FASS), a concept in the WiMAX network, is a method by which an MS can change its access station from frame to frame depending on the station selection mechanism. The access station can be an RS, BS, or MMRBS. The MS refers to transmitting/receiving data to/from one of the active stations (the anchor station) during any given frame.
Fast fading
Fast fading is the short term component associated with multipath propagation. It is influenced by the speed of the mobile terminal and the transmission bandwidth of the signal.

Fast Handoff
Fast Handoff is a way that access points can let authenticated users roam among different access points without losing authentication. Fast handoff also makes voice-over-IP possible. Fast handoff will be made possible with the 802.11f specification.
Fast Packet Switching
Fast Packet Switching is a packet-orientated, digital technology that transmits all data in a single packet format whether the information is video, voice or data. Fast packet switching uses short, fixed length packets (cells) and, via hardware switching, is capable of speeds between 100,000 and 1,000,000 packets/second.

FAW: Frame Alignment Word
Frame Alignment Word (FAW) is a unique digital word used by codecs to allow them to resynchronize to the framing structure in the event of errors.
FBSS: Fast Base Station Switching
Fast Base Station Switching (FBSS), defined in the IEEE 802.16-2005 (mobile WiMAX) network, is a method to allow switching between any type of access stations (like RS, BS, or MMR-BS). Switching can occur between the same type or different types of access stations.

FCC: Federal Communications Commission
Federal Communications Commission (FCC) is the regulatory body governing communications technologies in the US. established by the Communications Act of 1934, as amended, and regulates interstate communications (wire, radio, telephone, telegraph and telecommunications) originating in the United States.
FCCH: Frequency Correction Channel
Frequency Correction Channel(FCCH) is the logical channel in GSM systems used to transmit a frequency correction data burst of all "zeros". The resulting frequency shift seen by the mobile is then used for frequency correction.

FCH: Frame Control Header
Frame Control Header (FCH) is a field in the IEEE802.16-2004 WIMAX protocol. The FCH specifies the burst profile and the length of one or more DL bursts that immediately follow the FCH.
FDCCH: Forward Digital Control CHannel Forward Digital Control Channel (FDDCH), defined in the IS-136, provides cellular standards for TDMA-based networks. FDCCH includes all downstream signalling and control information from cell site to user equipment. FDCCH works together with RDCCH (Reverse Digital Control CHannel) which is for the upstream signaling and controling information. FDCCH can be divided into a few logic channels such as BCCH, SCF and SPACH.

FDD: Frequency Division Duplex
Frequency Division Duplex (FDD), used in cellular communication systems such as GSM, is a radio technology using a paired spectrum.
FDM: Frequency Division Multiplex
Frequency Division Multiplexing (FDM) is a technique by which the carrier bandwidth is divided into sub-channels of different frequency widths -- each carrying a signal at the same time in parallel. Each channel is 30 kHz. All the signals may be amplified, conducted, translated in frequency and routed toward a destination as a single signal, resulting in economies which are the motivation for multiplexing. Receivers at the receiving end separates the multiplexed signals by means of frequency passing or rejecting filters, and demodulates the results individually, each in the manner appropriate for the modulation scheme used for that band or group.

FDMA: Frequency Division Multiple Access
Frequency Division Multiple Access (FDMA) is a method of allowing multiple users to share the radio frequency spectrum by assigning each active user an individual frequency channel. In this practice, users are dynamically allocated a group of frequencies so that the apparent availability is greater than the number of channels.
FFT: Fast Fourier Transform
Fast Fourier Transform (FFT) is an efficient algorithm to compute the discrete Fourier transform (DFT) and its inverse. FFTs are of great importance to a wide variety of applications, from digital signal processing to solving partial differential equations to algorithms for quickly multiplying large integers.

FGD: Feature Group D
Feature Group D (FGD) is a local exchange carrier network service that, among other things, lets public-safety dispatch offices receive a 10-digit data stream, including the full call-back number, alongside wireless 911 calls. FGD is offered as a way by which wireless carriers can meet FCC-enhanced 911 rules and dispatch offices can overcome their current bandwidth limits. This access group is associated with equal access arrangements which allow the end user to have the same dialing plan (1 plus the telephone number) to reach any predetermined long distance phone companies of their choice.
Feature Group D
Feature Group D is a local exchange carrier network service that, among other things, lets public-safety dispatch offices receive a 10-digit data stream, including the full call-back number, alongside wireless 911 calls. Offered as a way by which wireless carriers can meet FCC enhanced 911 rules and dispatch offices can overcome their current bandwidth limits.

FEC: Forward Error Correction
Forward Error Correction (FEC) is a method of increasing the reliability of data communication. In one-way communication channels, a receiver does not have the option to request a re-transmission if an error was detected. Forward Error Correction is a method of sending redundant information with the data in order to allow the receiver to reconstruct the data if there was an error in transmission.
FER: Frame Erasure/Error Rate
Frame Erasure/Error Rate is a measure of the number of frames of data that contained errors and could not be processed. FER is usually expressed as a percentage or exponent.

FH: Frequency Hopping
Frequency Hopping (FH) is a periodic changing of frequency or frequency set associated with transmission. It is a sequence of modulated pulses having a pseudorandom selection of carrier frequencies.
FH-CDMA: Frequency Hopping - Code division multiple access
Frequency hopping - code division multiple access (FH-CDMA) is one of two basic modulation techniques used in spread spectrum signal transmission for CDMA-based wireless systems. It is the repeated switching of frequencies during radio transmission, often to minimize the effectiveness of the unauthorized interception or jamming of telecommunications.

FHMA: Frequency hopping multiple access
Frequency hopping multiple access (FHMA) is a digital technology used in Geotek Communications Inc.'s specialized mobile radio network.
FHSS: Frequency Hopped Spread Spectrum
Frequency Hopped Spread Spectrum (FHSS) is a spread-spectrum method of transmitting signals by rapidly switching a carrier among many frequency channels, using a pseudorandom sequence known to both transmitter and receiver. It is used in WLAN 802.11 physical layer.

FIRFinite Impulse Response
Finite Impulse Response (FIR) is a technique used to characterize electrical circuits and‚ networks in the time domain.
Fixed WiMax
Fixed WiMax refers to the fixed wireless broadband services as defined by the IEEE 802.16d (also known as IEEE 802.16-2004). IEEE 802.16d product profile utilizes the OFDM 256-FFT (Fast Fourier Transform) system profile. The Fixed WiMAX 802.16-2004 standard supports both time division duplex (TDD) and frequency division duplex (FDD) services -- the latter of which delivers full duplex transmission on the same signal if desired. The mobility features of WiMax are defined in IEEE 802.16e (or 802.16-2005).

Fixed Wireless
Fixed wireless refers to the over-the-air transmission of information to and from systems and end-user equipment that are stationary, rather than mobile. Operators of fixed wireless networks potentially can offer broadband services without having to lay expensive cable systems or deal with the complexities of mobility management.
Flat fading
Flat fading is a type of fading in a communications channel that attenuates or fades all frequencies in the channel in the same amount.

FLEX is the Motorola's flexible high-speed paging coding scheme that gives carriers more capacity on their networks and faster transmission time. FLEX also refers to the FLEX family of protocols: FLEX, InFLEXion and ReFLEX.
FM: Frequency Modulation
Frequency Modulation (FM) is a form of angle modulation in which the instantaneous frequency of a sine-wave carrier is caused to depart from the carrier frequency by an amount proportional to the instantaneous value of the modulating wave. In FM, signals of different frequencies represent different data values.

Foliage attenuation
Reductions in signal strength or quality is due to signal absorption by trees or foliage obstructions in the signal's line-of-sight path. For example, 800 MHz systems are seldom deployed in forested areas. Pine needles-nearly the same length as 800 MHz antennas can negatively affect signal reception in that band.
FOMA: Freedom of Mobile Multimedia Access

Freedom of Mobile Multimedia Access (FOMA) is the brand name for the 3G services being offered by Japanese mobile phone operator NTT DoCoMo. FOMA was the world's first W-CDMA 3G service when launched in 2001. FOMA is compatible with standard UMTS, both via the radio link as well as via USIM card exchange, and hence provides several alternative options for global roaming: either with or without change of handset.
Footprint in wireless communications refers to geographical areas in which an entity is licensed to broadcast its signal.

Forward Channel
Forward Channel is used by the base station to communicate with a mobile station.
Forward link
In radio communications, a forward link is the link from a fixed location (e.g., a base station) to a mobile user. If the link includes a communications relay satellite, the forward link will consist of both an uplink (base station to satellite) and a downlink (satellite to mobile user).

Frequency is the measurement of the number of times that a repeated event occurs per unit time. To calculate the frequency of an event, the number of occurrences of the event within a fixed time interval are counted, and then divided by the length of the time interval.
Frequency diversity
Frequency diversity is the simultaneous use of multiple frequencies to transmit information. This is a technique used to overcome the effects of multipath fading since the wavelength for different frequencies result in different and uncorrelated fading characteristics.

Frequency reuse
Frequency reuse is a technique of reusing frequencies and channels within a communications system to improve capacity and spectral efficiency. Frequency reuse is one of the fundamental concepts on which commercial wireless systems are based that involves the partitioning of an RF radiating area (cell) into segments of a cell. One segment of the cell uses a frequency that is far enough away from the frequency in the bordering segment that it does not provide interference problems. Frequency re-use in mobile cellular systems means that each cell has a frequency that is far enough away from the frequency in the bordering cell that it does not provide interference problems. The same frequency is used at least two cells apart from each other. This practice enables cellular providers to have many times more customers for a given site license.
Frequency selective fading
Frequency selective fading is a type of signal fading occurring over a small group of frequencies caused by a strong multipath component at those frequencies.

Fresnel Zone
Fresnel Zone is an elliptical area on either side of the straight line of sight that must also be clear for a long-range wireless network to work.
Fringe Area
Fringe Area is the outermost range of a cellular system where cellular signals may be weaker.

FRS: Family Radio Service
Family Radio Service is a very low power, short range two-way radio service in the 460 MHz band.
FRS: Fixed Relay Station
Fixed Relay Station (FRS) refers to a relay station that is permanently installed at a fixed location.

FSKFrequency Shift Keying
Frequency Shift Keying (FSK) is a form of modulation using multiple carrier frequencies to carry the digital information. The most common one is the two-frequency FSK system using the two frequencies to carry the binary ones and zeros.
FSSS: Fast Serving Station Switching
Fast Serving Station Switching (FSSS) refers to the serving station switching with which a Moble Station (MS) can change its serving station from frame to frame depending on the serving station selection mechanism. A serving station can be an RS, BS, or MMR-BS. Fast BS switching (FBSS) was defined in 802.16e, and the terminology is modified to allow switching between any types of serving stations (RS, BS, or MMR-BS). Switching can be either between a same type of serving stations or between different types of serving stations.

Full rate
Full rate refers to voice codecs in a communications system. Most frame formats are designed to accommodate full and half-rate channels, with the intention of implementing half-rate coding as the technology permits to double the capacity of the system. The full-rate codec uses all of the time-slots available.
Full user mobility
Full user mobility is a wireless classification under which users can access data while in motion, for example, in a car.

FUSC: Fully Used SubChannel
Fully Used SubChannel (FUSC), also known as Fully Used SubCarrier, is a method used in the WiMAX network that uses all the subchannels and employs full-channel diversity by distributing the allocated subcarriers to subchannels using a permutation mechanism. This mechanism is designed to minimize the probability of hits (probably of using the same physical subcarriers in adjacent cells and sectors) between adjacent sectors/cells by reusing subcarriers while frequency diversity minimizes the performance degradation due to fast fading characteristics of mobile environments.
FWA: fixed wireless access
Fixed wireless access, also known as wireless local loop, is a wireless system in which office or home users directly connect with the switching center of the telecommunications carrier or the inter-exchange channel to use the system.

Gain refers to the ratio of the output amplitude of a signal to the input amplitude of a signal. This ratio typically is expressed in dBs. The higher the gain, the better the antenna receives or transmits but also the more noise it includes.
GAN: Global Area Network
Global Area Network (GAN) is a network that is composed of different interconnected computer networks and covers an unlimited geographical area.

Gaussian channel
Gaussian channel is an RF communications channel having the properties of a wide-band uniform noise spectral density resulting in a random distribution of errors in the channel.
GEOS: Geo-stationary Earth Orbit Systems
Geo-stationary Earth Orbit Systems (GEOS) is a communications system with satellites in geosynchronous orbits -- 22,300 miles above the Earth.

Geosynchronous Orbit
A geosynchronous orbit has the same orbital period as the sidereal rotation period of the Earth. It has a semi-major axis of 42,164 km.
GERAN: GSM (GPRS)/EDGE Radio Access Network
GSM(GPRS)/EDGE Radio Access Network (GERAN) is the name given to the 3GPP standards for GSM(GPRS)/EDGE radio access, which has been specified to connect the A, Gb and Iu interfaces to the CN (Core Network). The architecture allows two BSS (Base Station Subsystem) to be connected to each other.

GGSN: Gateway GPRS Support Node
Gateway GPRS Support Node (GGSN) is a gateway from a cellular network to an IP network that allows mobile cell phone users to access the public data network (PDN) or specified private IP networks. The GPRS Core Network is the centralised part of the GPRS system and also provides support for UMTS-based 3G networks.
GHz: GigaHertz
GigaHertz (GHz) is one billion hertz, which is a measurement of frequency.

Gi interface
Gi interface is the reference point between a GPRS network and an external packet data network.
GIS: geographic information system
Geographical Information System (GIS) refers to a computer system capable of capturing, storing, analyzing, and displaying geographically referenced information, that is, data identified according to location. Practitioners also define a GIS as including the procedures, operating personnel, and spatial data that go into the system.

GLONASS: global navigation system
Global navigation system (GLONASS) is a Russian satellite location technology similar to global positioning system.
GMM/SM: GPRS Mobility Management / Session Management
GPRS Mobility Management/Session Management (GMM/SM) protocol supports mobility management functionality of a mobile such as GPRS attach, GPRS detach, security, routing area update, location update. The main function of the Session Management (SM) layer is to support PDP context handling of the user terminal. SM comprises of procedures for the PDP context activation, deactivation and modification. The GMM layer uses the services of the Radio Access Network Application Protocol (RANAP) over the Iu interface to provide these services.

GMM: GPRS Mobility Management
GPRS Mobility Management (GMM) is a GPRS signaling protocol that handles mobility issues such as roaming, authentication, and selection of encryption algorithms. GPRS Mobility Management, together with Session Management (GMM/SM) protocol, supports the mobility of user terminal so that the SGSN can know the location of a mobile station (MS) at any time and to activate, modify and deactivate the PDP sessions required by the MS for the user data transfer.
GMPCS: Global Mobile Personal Communications Services
Global Mobile Personal Communications Services (GMPCS) is a mobile satellite systems that will provide global wireless phone service.

GMSK: Gaussian Minimum Shift Keying
Gaussian Minimum Shift Keying (GMSK) is a modulation technique involving Gaussian filtering of the input data prior to its application to the phase modulator. This results in a narrowly occupied spectrum and better adjacent channel interference performance
Gn Interface
Gn Interface is the interface between GSNs within the same PLMN in a GPRS network. GPRS Tunneling Protocol (GTP) is a protocol defined on both the Gp and Gn interfaces between GSNs in a GPRS network.

GOS: Grade of Service
Grade of Service (GOS) is a measure of the success a subscriber is expected to have in accessing a network to complete a call. The grade of service is usually expressed as percentage of calls attempted by the subscriber during the busy-hour that are blocked due to insufficient network resources.
Gp Interface
Gp Interface is the Interface between GSNs within different PLMNs in a GPRS network. GPRS Tunneling Protocol (GTP) is a protocol defined on both the Gp and Gn interfaces between GSNs in a GPRS network.

GPRS: General Packet Radio Service
General Packet Radio Service (GPRS) technology runs at speeds of up to 115Kbit/sec., compared with the 9.6Kbit/sec. of older GSM systems. It enables high-speed wireless Internet and other communications such as e-mail, games and applications. It supports a wide range of bandwidths and is an efficient use of limited bandwidth. It's particularly suited for sending and receiving small amounts of data, such as e-mail and Web browsing, as well as large volumes of data.
GPS: Global Positioning System
The Global Positioning System (GPS) is a "constellation" of 24 satellites that orbit the Earth at a height of 10,900 miles, making it possible for people using ground receivers to determine their geographic location within 10 to 100 meters. The satellites use simple mathematical calculations to broadcast information that is translated as longitude, latitude and altitude by Earth-based receivers.

GPT: GPRS Tunneling Protocol
GPRS Tunneling Protocol (GTP) is a protocol used by the GPRS backbone network for packet switching. GTP is a protocol defined on both the Gn and Gp interfaces between GSNs in a GPRS network.
Ground Station
Ground Station, also called a downlink station, refers to the collection of communications equipment designed to receive signals from (and usually transmit signals to) satellites.

GSM 1800
GSM 1800, also known as DCS 1800 or PCN, is a moble network working on a frequency of 1800 MHz. It is used in Europe, Asia-Pacific and Australia.
GSM 1900
GSM 1900, also known as PCS 1900, is a mobile network working on a frequency of 1900 MHz. It is used in the US and Canada and is scheduled for parts of Latin America and Africa.

GSM 900
GSM 900, or just GSM, is the world's most widely used digital network -- now operating in over 100 countries around the world, particularly in Europe and Asia Pacific.
GSM plus
GSM plus is an enhanced version of global system for mobile communications (GSM) technology that will be developed to meet IMT-2000 capabilitiesGSM: Global System for Mobile Communications Global System for Mobile Communications (GSM), origionally known as Groupe Special Mobile, is a digital cellular system defined by ETSI based on TDMA narrowband technology. GSM allows up to eight simultaneous communications on the same frequency. GSM is widely deployed in Europe and some Asian Countries, competing with CDMA which was developed by Qualcomm and deployed mainly in the US.

GSM-R: GSM for Railway networks
Global system for mobile communications for Railway networks (GSM-R) uses standard base station and switching infrastructure to provide fast data transmission for railwaysGSN: GPRS Support Nodes GPRS Support Node (GSN) is a network node which supports the use of GPRS in the GSM core network. All GSNs should have a Gn interface and support the GPRS tunnelling protocol. There are two key variants of the GSN: the GGSN and the SGSN.
GTP: GPRS Tunnelling Protocol
GPRS Tunnelling Protocol (GTP) allows end users of a GSM or UMTS network to move from place to place whilst continuing to connect to the internet as if from one location at the GGSN. It does this by carrying the subscriber's data from the subscriber's current SGSN to the GGSN which is handling the subscriber's session. GTP version zero supports both signalling and user data under one generic header. It can be used with UDP (User Datagram Protocol) or TCP (Transmission Control Protocol) on the registered port 3386. GTP version one is used only on UDP. The control plane protocol GTP-C (Control) using registered port 2123 and the user plane protocol GTP-U (User) using registered port 2152.

GTP Tunnel
GTP Tunnel is used to communicate between an external packet data network and a mobile station in a GPRS network. A GTP tunnel is referenced by an identifier called a TID and is defined by two associated PDP contexts residing in different GSNs. A tunnel is created whenever an SGSN sends a Create PDP Context Request in a GPRS network.
Guard Band
Guard Band is a set of frequencies or band-width used to prevent adjacent systems from interfering with each other. Guard bands are typically used between different types of systems at the edges of the frequency allocations.

GWEN: Ground Wave Emergency Network
Ground Wave Emergency Network (GWEN) is a communications system that the US military constructs. It operates in a very-low-frequency range, with transmissions between 150 and 175 kHz. This range was selected because its signals travel by means of waves that have a tendency to hug the ground rather than by radiating into the atmosphere. This signal drops off sharply with distance -- a single GWEN stations transmits in a 360 circle to a distance of 250 to 300 miles. The entire GWEN system consists of approximately 300 such stations spread across the United States, each with a tower 300-500 feet high. The stations are from 200 to 250 miles apart, so that a signal can go from coast to coast or from one station to another. When the system is completed around 1993, the entire civilian population of the United States will be exposed to the GWEN Transmissions

HAAT: Height Above Average Terrain
Height Above Average Terrain (HAAT) is a measure of an antenna's height above average terrain. This value is used by the FCC in determining compliance with height limitations and transmitting powers for high sites.
Half rate
Half rate is a term used in voice codecs in a communications system. Most frame formats are designed to accommodate full and half-rate channels, with the intention of implementing half-rate coding as the technology permits to double system capacity. The half rate codec uses only half of the time-slots in the frame.

Hamming code
Hamming code is a well known simple class of block codes capable of detecting up to two errors and correcting one. Although not particularly powerful, they are one of the "perfect" codes in that its standard array has all of the error patterns that can exist for single errors.
Hand Off (Handoff)
Hand Off (handoff) is the process of transferring a call in progress from the current base station to another without interruption as the user moves out of range of the current base station.

Hand Over
Hand Over refers to the passing of a call signal from one base station to the next as the user moves out of range or the network software re-routes the call.
HARQ: Hybrid Automatic Repeat reQuest
Hybrid Automatic Repeat reQuest (HARQ or Hybrid ARQ) is a sheme wherein information blocks are encoded for partial error correction at receiver and additional, uncorrected errors are retransmitted.

Hard Hand Off
Hard Hand Off, used in CDMA systems, describes a hand-off involving a frequency change. The hard hand-off is a break before make hand-off just like in other wireless systems and must be used where the current and hand-off candidate base stations do not use the same RF channel. See also soft hand-off.
Hata Model
Hata Model, also known as the Okamura-Hata model, is used to predict signal strength levels in land-mobile systems.

HCI: Host Controller Interface
A geosynchronous orbit has the same orbital period as the sidereal rotation period of the Earth. It has a semi-major axis of 42,164 km.
HDML: Handheld Device Markup Language
Handheld Device Markup Language(HDML) Specifications allow Internet access from wireless devices such as handheld personal computers and smart phones. This language is derived from hypertext markup language (HTML).

HDTP: Handheld Device Transport Protocol
Handheld Device Transport Protocol (HDTP) is optimized for HDML. It presents the HDML to the HDML interpreter in an appropriate format.
Hertz(Hz) is the measure of frequency which means cycles per second.

HHO: Hard Hand-Off
Hard Hand Off, used in CDMA systems, describes a hand-off involving a frequency change. The hard hand-off is a break before make hand-off just like in other wireless systems and must be used where the current and hand-off candidate base stations do not use the same RF channel. See also soft hand-off.
High-gain Antenna
High-gain Antenna is a type of antenna that significantly increases signal strength. High-gain antennas are necessary for long-range wireless networks.

Hidden Node Problem
The hidden node problem occurs in the wireless networking when a node is visible from a wireless hub, but not from other nodes communicating with said hub. This leads to difficulties in media access control. Hidden nodes in a wireless network refer to nodes which are out of range of other nodes or a collection for nodes. Take a physical star topology with an Access Point with many nodes surrounding it in a circular fashion; each node is within the communication range of the Access Point, however, not each node can communicate with each other.
HLR: home location register
Home Location Register (HLR) is a database residing in a local wireless network that checks the identity of a local subscriber. HLR contains information about subscribers to a mobile network and registers subscribers for a particular service provider. The HLR stores "permanent" subscribers' information (rather than temporary subscribers' data, which a VLR manages), including the service profile, the location information, and the activity status of the mobile user.

HomePNA is a networking standard that uses standard telephone wiring. HomePNA is primarily useful for bridging wireless networks across obstacles (like brick walls) that block radio waves. HomePNA 2.0 runs at 10 Mbps, and the just-defined HomePNA 3.0 runs at 128 Mbps.
HomeRF is a networking standard for home wireless communication, which is a competitor to Wi-Fi that integrates voice, data, and streaming media into a single wireless signal.

Hot spot or hotspot
Hot spot (hotspot) is an area, such as a hotel, restaurant or airport, that offers Wi-Fi access, either free or for a fee.
HPSK: Hybrid Phase Shift Keying
Hybrid Phase Shift Keying (HPSK), also known as Orthogonal Complex Quadrature Phase Shift Keying (OCQPSK), is the spreading technique used in the reverse link of 3G systems to reduce the peak-to-average ratio of the signal by reducing zero crossings and 0 degree phase transitions.

HR/DSSS PHY: High Rate / Direct Sequence Spread Spectrum Physical Layer
High Rate/Direct Sequence Spread Spectrum Physical Layer (HR/DSSS PHY) is the enhanced physical layer defined by IEEE 802.11b which supports data transfer at up to 11Mbps. Unlike the earlier versions of IEEE 802.11 which supported data rates of up to 2Mbps, HR/DSSS uses complementary code keying which divides the chip stream into a number of 8-bit code symbols.
HRPD: High Rate Packet Data
High Rate Packet Data (HRPD), also known as TIA/EIA IS-856 or 1xEV-DO, is a packet data protocol in the 3G mobile communicaitons network based on CDMA2000.

HSCSD: High Speed Circuit Switched Data
High Speed Circuit Switched Data (HSCSD) is a circuit-linked technology for higher transmission speeds -- up to 57 kilobits per second -- primarily in GSM systems.
HSDPA: High-Speed Downlink Packet Access
High-Speed Downlink Packet Access (HSDPA), also called 3.5G (or "3½G"), is a new mobile telephony protocol. High Speed Downlink Packet Access (HSDPA) is a packet-based data service in W-CDMA downlink with data transmission up to 8-10 Mbit/s (and 20 Mbit/s for MIMO systems) over a 5MHz bandwidth in WCDMA downlink. HSDPA implementations include Adaptive Modulation and Coding (AMC), Multiple-Input Multiple-Output (MIMO), Hybrid Automatic Request (HARQ), fast scheduling, fast cell search, and advanced receiver design.

HS-DPCCH: High-Speed Dedicated Physical Control Channel
High Speed Dedicated Physical Control Channel (HS-DPCCH) was introduced in the 3GPP release 5 of WCDMA as a new uplink code channel for control purposes. Besides being the 3rd uplink code channel, the HSDPCCH is not continuously transmitted and is not necessarily time aligned with the other WCDMA uplink channels. As a result, varying power relations to the dedicated uplink channels (DPCCH and DPDCH) are obtained.
HS-PDSCH: High-Speed Physical Downlink Shared Channel
High-Speed Physical Downlink Shared Channel (HS-PDSCH) is channel added to UMTS to increase downlink data rates that is defined in Release 5 of the UMTS specifications and is part of HSDPA. An HS-PDSCH may use QPSK or 16QAM modulation symbols. In the figure above, M is the number of bits per modulation symbols i.e. M=2 for QPSK and M=4 for 16QAM.

HS-DSCH: High-Speed Downlink Shared Channel
High-Speed Downlink Shared Channel (HS-DSCH), a channel added to UMTS to increase downlink data rates that is defined in Release 5 of the UMTS specifications, is a transport channel shared among all users that are using HSPDA for their interactive/background radio access bearer. HS-DSCH can be mapped onto one or several physical channels (also known as codes) all using spreading factor 16.
HSPA: High Speed Packet Access
High-Speed Downlink Packet Access (HSDPA), specified in 3GPP Release 5, extends WCDMA with additional transport and control channels, such as the high-speed downlink shared channel (HS-DSCH), which provides enhanced supports for interactive, background and, to some extent, streaming services.

HS-SCCH: High-Speed Shared Control Channel
High-Speed Shared Control Channel (HS-SCCH) is a channel added to UMTS to increase downlink data rates that is defined in Release 5 of the UMTS specifications and is part of HSDPA.
HSS: Home Subscriber Service
Home Subscriber Service (HSS), a key component in the IP Multimedia Subsystem (IMS), refers to a system including the master user database and software that supports IMS network entities that handle calls and sessions. HSS contains user profiles, performs authentication and authorization of the user, and can provide information about the physical location of user. HSS is similar to the GSM Home Location Register. The entities that communicate with the HSS are the application server (AS) that hosts and executes services in the IMS environment, and the Call State Control Function servers (CSCF). The User Profile contains information about the current user when a user is registering on the network. The S-CSCF will receive the profile in a User-data Attribute Value Pair (AVP) format.

HSUPA: High-Speed Uplink Packet Access
High-Speed Uplink Packet Access (HSUPA) is a data access protocol for mobile phone networks with extremely high upload speeds of up to 5.8 Mbit/s. Similar to HSDPA (High-Speed Downlink Packet Access), HSUPA is considered 3.75G or sometimes 4G.
HERTZ (Hz) is a measurement of frequency in cycles per second. One Hertz is one cycle per second.

IBSS: Independent Basic Service Set
Independent Basic Service Set (IBSS), also known as an ad hoc network. It is an 802.11 network comprising a collection of stations that communicate with each other, but not with a network infrastructure. Do not confuse it with Infrastructure BSS.
IBSS: Infrastructure BSS
Infrastructure BSS (IBSS) is an 802.11 network comprising an access point and stations. The access point forwards information to target stations or to a fixed network.

iDEN: Integrated Digital Enhanced Network
Integrated Digital Enhanced Network (iDEN) is a Motorola-enhanced mobile radio network technology that integrates two-way radio, telephone, text messaging, and data transmission into a single network. iDEN wireless handsets are utilized in a variety of work environments ranging from manufacturing floors to executive conference rooms as well as mobile sales forces.
IF: Intermediate Frequency
Intermediate Frequency (IF) is a frequency to which a carrier frequency is shifted as an intermediate step in transmission or reception. Intermediate electromagnetic frequencies is generated by a superheterodyne radio receiver.

IMSEI: International Mobile Station Equipment Identity
International Mobile Station Equipment Identity (IMSEI) is an identification number assigned to GSM mobile stations that uniquely identifies each one. It is a 15-digit serial number that contains a type approval code, final assembly code and serial number.
IMEI: International Mobile Equipment Identity
The International Mobile Equipment Identity (IMEI) is a number unique to every GSM and UMTS mobile phone. It is usually found printed on the phone underneath the battery and can also be found by dialling the sequence *#06# into the phone. The IMEI number is used by the GSM network to identify valid devices and therefore can be used to stop a stolen phone from accessing the network. For example, if a mobile phone is stolen, the owner can call his or her network provider and instruct them to "ban" the phone using its IMEI number. This renders the phone useless, regardless of whether the phone's SIM is changed.

I-Mode or iMode
I-Mode, also known as iMode, is a popular wireless Internet service by NTT DoCoMo Inc. in Japan. It's based on a simplified form of HTML and delivers packet-based information -- such as games, e-mail and even business applications -- to handheld devices.
IMPI: IP Multimedia Private Identity
IP Multimedia Private Identity (IMPI) is one of the two identities used by an IP Multimedia Subsystem (IMS). The other one is the IP Multimedia Public Identity (IMPU). Both are not phone numbers or other series of digits, but URIs, that can be digits (a tel-uri, like tel:+1-555-123-4567) or alphanumeric identifiers (a sip-uri, like sip:name@domain.com). The IMPI is unique to the phone, and you can have multiple IMPU per IMPI (often a tel-uri and a sip-uri). The IMPU can also be shared with another phone, so both can be reached with the same identity (for example, a single phone-number for an entire family).

IMPU: IP Multimedia Public Identity
IP Multimedia Public Identity (IMPU) is one of the two identities used by an IP Multimedia Subsystem (IMS). The other one is the IP Multimedia Private Identity (IMPI). Both are not phone numbers or other series of digits, but URIs, that can be digits (a tel-uri, like tel:+1-555-123-4567) or alphanumeric identifiers (a sip-uri, like sip:name@domain.com). The IMPI is unique to the phone, and you can have multiple IMPU per IMPI (often a tel-uri and a sip-uri). The IMPU can also be shared with another phone, so both can be reached with the same identity (for example, a single phone-number for an entire family).
IMS: IP Multimedia Subsystem
The IP Multimedia Subsystem (IMS) is a standardised Next Generation Networking (NGN) architecture for telecom operators that want to provide mobile and fixed multimedia services. It uses a Voice-over-IP (VoIP) implementation based on a 3GPP standardised implementation of SIP, and runs over the standard Internet Protocol (IP). Existing phone systems (both packet-switched and circuit-switched) are supported.

IMS-MGW: IP Multimedia Subsystem Media Gateway
IP Multimedia Subsystem Media Gateway (IMS-MGW), a component in the IP Multimedia Subsystem (IMS) 3G architecture, can terminate bearer channels from a switched circuit network and media streams from a packet network. It can support media conversion, bearer control, and payload processing (e.g., using codecs, echo cancellers, or conference bridges).
IM-HSS: IP Multimedia - Home Subscriber Service
The IP Multimedia - Home Subscriber Service (IM-HSS), also known as HSS, is the IP Multimedia Subsystem (IMS) service and user data repository. It plays a key role in provisioning, service creation, enabling subscriber data, and managing control, roaming and interconnection. The IM-HSS: (1) Supports IMS level authentication and authorization; (2) Maintains IMS subscriber profile(s) independent of access types; (3) Maintains service-specific data; (4) Keeps track of currently assigned S-CSCF and (5) Supports CSCF and AS access.

IMSI: International Mobile Station Identity
International Mobile Station Identity (IMSI) is a unique 15-digit number assigned to a mobile station at the time of service subscription. It contains a mobile country code, a mobile network code, mobile subscriber identification number, and a national mobile subscriber identity. The MS sends the IMSI to a BTS for identification of the MS in the GSM network. The BTS looks for the IMSI in the HLR.
IMSI: International Mobile Subscriber Identity
International Mobile Subscriber Identity (IMSI) is a unique number that is associated with all GSM and Universal Mobile Telecommunications System (UMTS) network mobile phone users. The number is stored in the Subscriber Identity Module (SIM). It is sent by the mobile phone to the network and is also used to acquire other details of the mobile in the Home Location Register (HLR) or as locally copied in the Visitor Location Register. In order to avoid the subscriber being identified and tracked by eavesdroppers on the radio interface, the IMSI is sent as rarely as possible and a randomly generated TMSI is sent instead.

IMT-2000: International Mobile Telecommunication 2000
International Mobile Telecommunication 2000 (IMT-2000) is a group of technologies defined by ITU-T for the third generation mobile telephony. It can also be applied to mobile telephone standards that meet a number of requirements in terms of transmission speed and other factors.
IMTA: International Mobile Telecommunications Association
International Mobile Telecommunications Association (IMTA) is a trade group serving specialized mobile radio and public access mobile radio carriers around the world.

IMTS: Improved Mobile Telephone Service
Improved Mobile Telephone Service (IMTS) is the commercial form of mobile telephone service preceding cellular that allowed users to place and receive their own calls through the use of a dial or keypad on the telephone.
IN: Intelligent Network
Intelligent Network (IN) often referred to as the Advanced Intelligent Network, this is a network of equipment, software and protocols used to implement features on the network and support switching and control functions.

InFLEXion is the narrowband PCS technology developed by Motorola Inc. that allows for voice paging.
Infrared is the electromagnetic waves whose frequency range is above that of microwaves, but below that of the visible spectrum.

Interferance is the effect that occurs when undesired signals inhibits or degrades the reception of a desired signal.
IR: Incremental Redundancy
Incremental redundancy (IR) is the feature used by EDGE (EGPRS) systems to get maximum performance out of the available bandwidth. It works by first sending only the minimum amount of redundant data, i.e. in most cases, no redundant data. If the data is not decoded properly, the system will resend the same data using a different puncture or coding scheme, increasing the amount of redundant data and the likelihood of recovering from the errors. If data is retransmitted using a different puncture or coding scheme, it is then recombined with the first transmission to increase redundancy.

IRC: Infrared communication
InfraRed Communication (IRC), is employed in short-range communications among computer peripherals and personal digital assistants. These devices usually conform to standards published by IrDA, the Infrared Data Association. Remote controls and IrDA devices use infrared light-emitting diodes (LEDs) to emit infrared radiation which is focused by a plastic lens into a narrow beam. The beam is modulated, i.e. switched on and off, to encode the data. The receiver uses a silicon photodiode to convert the infrared radiation to an electric current. It responds only to the rapidly pulsing signal created by the transmitter, and filters out slowly changing infrared radiation from ambient light. Infrared communications are useful for indoor use in areas of high population density. IR does not penetrate walls and so does not interfere with other devices in adjoining rooms.
IrDA: Infrared Data Association
Infrared Data Association (IrDA) is an industry organization that creates standards for hardware and software used in infrared communications. Information is transferred via rays of light, as opposed to radio waves. Most TV remote controls use infrared. IrDA standards have been implemented on various computer platforms and, more recently, have become available for many embedded applications.

IrOBEX: Infrared OBject Exchange
Infrared OBject EXchange (IrOBEX) or OBEX) is a communications protocol that facilitates the exchange of binary objects between devices. It is maintained by the Infrared Data Association but has also been adopted by the Bluetooth Special Interest Group and the SyncML wing of the OMA. One of OBEX's earliest popular applications was in the Palm III personal digital assistant. This PDA and its many successors use OBEX to exchange business cards, data, even applications.
IS-136, replacing IS-54 of the original tDMA standard, is the second-generation (2G) mobile phone systems used in the D-AMPS. IS-136 uses Time Division Multiple Access(TDMA) as an air interface.

IS-2000, also known as EIA Interim Standard 2000, is a standard for current CDMA systems providing a migration path to 3G services.
IS-41, also known as ANSI-41 since it is a standard defined by ANSI, is a specification for identifying and authenticating users, and routing calls on mobile phone networks based on MPS (analog), IS-136 (TDMA) and CDMA technologies. The standard also defines how users are identified, and calls are routed when roaming across different networks. GSM and WCDMA networks use a different standard known as MAP for the same purpose.

IS-54, an EIA Interim Standard for U.S. Digital Cellular (USDC), is the original TDMA digital standard implemented in 1992. This standard was the first to permit the use digital channels in AMPS systems. It used digital traffic channels but retained the use of analog control channels. This standard was replaced by the IS-136 digital standard in 1996.
The IS-634 interface is a standard defined by TIA/EIA that defines the messaging interface between a TDMA Base Station (BS) and a Mobile Switching Center (MSC). This interface uses the services provided by Connection Oriented SCCP for its transport layer. IS-634 is deployed worldwide in the cdmaOne mobile wireless networks.

IS-661 is a North American standard for 1.9 GHz wireless spread spectrum radio-frequency access technology developed by Omnipoint Corp. IS-661, for which Omnipoint was awarded a pioneer's preference license for the New York City market, is based on a composite of code division multiple access and time division multiple access technologies. The company says IS-661 reduces infrastructure costs and allows higher data speeds than mainstream GSM or TDMA platforms.
Interim Standard 95 (IS-95), is the first CDMA-based digital cellular standard pioneered by Qualcomm. The brand name for IS-95 is cdmaOne. IS-95 is also known as TIA-EIA-95. It is a 2G mobile telecommunications standard that uses CDMA, a multiple access scheme for digital radio, to send voice, data and signaling data (such as a dialed telephone number) between mobile telephones and cell sites.

IS-95a, an EIA Interim Standard 95, is the original digital mobile telephony standard based on CDMA technology. It is applied in the cdmaOne mobile network.
IS-95b is an upgraded version of IS-95a for the cdmaOne mobile network that increases the maximum data rate to 115.2 kb/s.

ISI: Inter-Symbol Interference
Inter-Symbol Interference (ISI) is an interference effect where energy from prior symbols in a bit stream is present in later symbols. ISI is normally caused by filtering of the data streams.
ISIM: IP Multimedia Services Identity Module
IP Multimedia Services Identity Module (ISIM) is an application running on a Universal Integrated Circuit Card (UICC) smart card in a 3G mobile telephone in the IP Multimedia Subsystem (IMS). It contains parameters for identifying and authenticating the user to the IMS. The ISIM application can co-exist with SIM and USIM on the same UICC making it possible to use the same smart card in both GSM networks and earlier releases of UMTS.

iTAP, also known as T9 TM text input, is a application installed on wireless phones and handheld devices that allows you to type messages with just one key press per letter using the keypad. It is a much easier text input method than the traditional multi-tapping.
ITU: International Telecommunications Union
International Telecommunications Union (ITU) is a United Nations agency that deals with telecommunications issues.

IWF: Interworking Function
Interworking Function (IWF) is a technique for interfacing data between a wireless system and the telephone network. It usually involves the use of modems or data terminal adapters to convert the data transmitted over the air interface and mobile network to a format that can be recognized and carried by the public telecommunications network.
J2ME: Java 2 Platform, Micro Edition
Java 2 Platform Micro Edition (J2ME) is a technology that allows developers to use the Java programming language to create applications for mobile wireless devices.

Jamming refers to the interference with the air radio transmission. It may be used by people who is trying to disturb the receiver from receiving the radio signal at a target frequency.
JavaPhone is a Java API specification controlling contacts, power management, call control, and phone book management. It is intended specifically for the programming requirements of mobile phones.

JTACS or J-TAGS: Japanese Total Access Communication System
Japanese Total Access Communication System (JTAGS) is a 1G technology deployed in Japan based on the European TACS system. JTAGS is operating in the 900-MHz band.
JTAPI: Java Telephony API
The Java Telephony API (JTAPI) is an extensible API that offers an interface to all call control services. The services include those needed in a consumer device up to those of enterprise call centers. JTAPI is part of the JavaPhone API.

Ka-Band refers to the bandwidth of electromagnetic wave between 33 GHz to 36 GHz, which is primarily used in satellites operating at 30 GHz uplink and 20 GHz downlink for mobile voice communications.
Key Pulse Signal
Key-pulse signal is the first signal in an multifrequency outpulsing format, which is a control signal used to prepare the remote customer installation to receive digits.

KHz: KiloHertz
One kHz (KiloHertz) is equal to 1,000 Hertz, which is a measurement of frequency.
kpbs: Kilobits per second
kpbs (Kilobits per second) is a measurement of data rate, for example, data services for 2G operates at maximum speed of 9.6kbps.

Ku-Band refers to the bandwidth of electromagnetic wave between 12 GHz to 14 GHz, which is primarily used in satellites operating at 14 GHz uplink and 11 GHz downlink in supporting braodband TV and Direct Broadcast Satellite (DBS) system (DSS).
L2CAP: Logical Link Control and Adaptation Protocol
Logical Link Control and Adaptation Protocol, typically short as L2CAP, is used within the Bluetooth protocol stack at the data link layer. It passes packets to either the Host Controller Interface (HCI) or on a hostless system, directly to the Link Manager.

LAI: Location Area Identity
Location Area Identity (LAI) is the information carried in the SIM of GSM handsets that identify the subscriber's home area. This is used for billing and sub-net operation purposes.
LASCDMA: Large Area Synchronized Code Division Multiple Access
Large Area Synchronized Code Division Multiple Access (LASCDMA) is a technology developed by LinkAir that offers a higher spectral efficiency and moving speed for better mobile-application support.Also, its asymmetric traffic, higher throughput, and smaller delay provide improved IP support. Currently, LAS-CDMA is being considered as phase 2 of the 1xEV standards. A LAS-CDMA TDD variant is compatible with systems such as TD-SCDMA.

LDPC code: Low-Density-Parity-Check code
A low-density parity-check code (LDPC code) is an error-correcting code and a method of transmitting a message over a noisy transmission channel. While LDPC and other error correcting codes cannot guarantee perfect transmission, the probability of lost information can be made as small as desired. LDPC was the first code to allow data transmission rates close to the theoretical maximum, the Shannon Limit.
LEAP: Lightweight Extensible Authentication Protocol
Lightweight Extensible Authentication Protocol (LEAP), also known as Cisco-Wireless EAP, is a Cisco security technology that builds on Wi-Fi's WEP encryption. Basically, it changes the WEP key dynamically during a session to make it less likely that a snooper will be able to derive the key. LEAP provides username/password-based authentication between a wireless client and a RADIUS server like Cisco ACS or Interlink AAA. LEAP is one of several protocols used with the IEEE 802.1X standard for LAN port access control.

Lee's model
Lee's model is a slope-intercept propagation prediction model developed at Bell Laboratories and popularized by William Lee. The model assumes an initial condition at a short distance from a base station and uses that as one end of a slope intercept model to predict path loss between a base station and a mobile unit.
LEO: Low Earth Orbit
Low Earth Orbit (LEO) is the orbit between 700 and 2,000 kilometers above the Earth for Mobile communications satellite.

Link budget
Link budget is a calculation involving the gain and loss factors associated with the antennas, transmitters, transmission lines and propagation environment used to determine the maximum distance at which a transmitter and receiver can successfully operate.
LMDS: Local Multipoint Distribution System
Local multipoint distribution system (LMDS) is the broadband wireless technology used to deliver voice, data, Internet, and video services in the 25-GHz and higher spectrum (depending on licensing). As a result of the propagation characteristics of signals in this frequency range, LMDS systems use a cellular-like network architecture though services provided are fixed, not mobile. In the United States, 1.3 MHz of bandwidth (27.5 B 28.35 GHz, 29.1 B 29.25 GHz, 31.075 B 31.225 GHz, 31 B 31.075 GHz, and 31.225 B 31.3 GHz) has been allocated for LMDS to deliver broadband services in a point-to-point or point-to-multipoint configuration to residential and commercial customers. This tutorial details the underlying technology inherent in offering voice, data, Internet, and video services over LMDS through integration with the wireline environment.

LMP: Link Manager Protocol
Link Manager Protocol (LMP) is a data link layer protocol in the Bluetooth protocol stack. LMP carries out link setup, authentication, link configuration and other protocols. It discovers other remote Link Manager (LM) and communicates with them via the Link Manager Protocol (LMP). To perform its service provider role, the LM uses the services of the underlying Link Controller (LC).
LNA: Low Noise Amplifier
Low Noise Amplifier (LNA) is a receiving preamplifier having very low internal noise characteristics placed very near the antenna of a receiver to capture the C/N before it can be further degraded by noise in the receiving system.

LNP: Local Number Portability
Local Number Portability (LNP) is the capability that allows wireless customers to switch carriers but retain the same phone number. Wireless portability is expected to become a reality by the end of 2003.
Location registration
Location registration is one of several computer databases used to maintain location and other information on mobile subscribers. See HLR and VLR.

Location Server
Location Server allows end users to connect real-time location information from mobile service operator with mapping and routing information. Location server enables mobile service providers to provide their end-users with personalized contents that are location-dependent.
Logic Channel
Logic Channel is a communications channel derived from a physical channel. A physical channel, i.e. RF channel, typically carries a data stream that contains several logical channels. These usually include multiple control and traffic channels.

LOS: Line of Sight
Line of Sight (LOS) describes an unobstructed radio path or link between the transmitting and receiving antennas of a communications system. The opposite to LOS is NLOS, or Non Line of Sight.
LOS: Loss of Signal
Loss of signal (LOS) is a condition where the received signal drops below threshold due to a terrain obstruction or other phenomenon increasing the link budget loss beyond design parameters.

LPA: Linear Power Amplifier
Linear Power Amplifier (LPA) is the final amplification stage in a multicarrier transmitter that has been designed and optimized to produce a linear response. By operating in the linear mode, the amplifier reduces the non-linear effects that produce intermodulation products and side-lobe spectra that cause adjacent channel interference.
LTE: Long Term Evolution
Long Term Evolution (LTE), sometimes also referred to as 3G LTE or Super-3G, is the 3GPP radio technology evolution architecture. Its full name is UTRA-UTRAN Long Term Evolution (LTE) and 3GPP System Architecture Evolution (SAE).

LPC: Linear Predictive Coding
Linear Predictive Coding (LPC) is a speech encoding scheme that uses periodic pulses to excite a filter, similar to the way human voice is produced. The code is predictive in that it uses knowledge of past data (represented as vectors) to predict future values in a feed forward manner.
LSB: Least Significant Bit
Least Significant Bit (LSB), in a binary coding scheme, is the bit having the least numerical value. Analogous to the units position in a decimal number.

Lu is one of four interfaces connecting the UTRAN internally or externally to other functional entities. The other three are Uu, lub and lur. The lu interface is an external interface that connects the RNC to the Core Network (CN). Lu is the standardized interface between a Radio Network Controller Network and Packet Subsystem (e.g. RNC-3GSGSN).
Lub is one of four interfaces connecting the UTRAN internally or externally to other functional entities. The other three are Uu, lu and lur. The lub is an internal interface connecting the RNC with the Node B. And at last there is the lur interface which is an internal interface most of the time, but can, exceptionally be an external interface too for some network architectures. Lub is the interface between a Base Station and Radio NetworkController.

Lur is one of four interfaces connecting the UTRAN internally or externally to other functional entities. The other three are lu, Uu, and lub. The lur interface which is an internal interface most of the time, but can, exceptionally be an external interface for some network architectures, too. The lur connects two RNCs with each other.
MAC address
MAC address (Media Access Control address) is the address associated with every hardware device on the network. Every wireless 802.11 device has its own specific MAC address hard-coded into it. This unique identifier can be used to provide security for wireless networks. When a network uses a MAC table, only the 802.11 radios that have had their MAC addresses added to that network's MAC table are able to get onto the network.

MACRO Cell, also known as macrocell, is a large cell in a wireless system capable of covering a large physical area. Macrocells are used in rural areas and other areas where subscriber or traffic densities are low.
MAHO: Mobile Assisted Handoff
Mobile Assisted Handoff (MAHO) is a handoff technique involving feedback from the mobile station as part of the handoff process. The feedback is usually in the form of signal level and quality measurements on the downlink and signal level measurements from neighbor cells.

MAI: Multiple Access Interference
Multiple Access Interference (MAI) is a type of interference caused by multiple cellular users who are using the same frequency allocation at the same time. In both 2G and 3G moble networking, each user is then given a pair of frequencies (uplink and downlink) and a time slot during a frame. Different users can use the same frequency in the same cell except that they must transmit at different times. This multiple-access interference can present a significant problem if the power level of the desired signal is significantly lower (due to distance) than the power level of the interfering user.
MANET: Mobile Ad Hoc Network
Mobile Ad Hoc Network (MANET) refers to a type of mobile network in which each node has the ability to act as a router, permitting adaptable multihop communications. The establishment and maintenance of these routes, however, is severely affected by the stochastic nature of wireless communications, making it diffcult to implement such nets in practice.

MAP: Mobile Application Part
The Mobile Application Part (MAP), one of the protocols in the SS7 suite, allows for the implementation of the mobile network (GSM) signaling infrastructure. The premise behind MAP is to connect the distributed switching elements, called mobile switching centers (MSCs), with a master database, called the Home Location Register (HLR). The HLR dynamically stores the current location and profile of a mobile network subscriber. The HLR is consulted during the processing of an incoming call.
Master Access Point
Master Access Point is the primary access point in a wireless network that uses WDS to extend range. The master access point shares the Internet connection with the rest of the remote, or relay access points, along with all the wireless clients.

Matched filter
Matched filter is the receiver filter with impulse response equal to the timereversed,complex conjugate impulse response of the combined transmitter filter-channel impulse response.
MBMS: Multimedia Broadcast Multicast Service
Multimedia Broadcast Multicast Service (MBMS) is a broadcasting service that can be offered via existing GSM and UMTS cellular networks. The infrastructure offers an option to use an uplink channel for interaction between the service and the user, which is not a straightforward issue in usual broadcast networks, as for example conventional digital television is only a one-way (unidirectional) system. MBMS uses multicast distribution in the core network instead of point-to-point links for each end device.

MBOA: MultiBand OFDM Alliance
MultiBand OFDM Alliance (MBOA) was an industrial association with a focus on the Ultra WideBand wireless communication technologies. The Multi-Band OFDM Alliance and the WiMedia Alliance were merged in 2005, under the name or WiMedia Alliance to align goals more fully.
MBS: Mobile Broadband Systems
Mobile Broadband Systems (MBS) are extensions of the wired B-ISDN system. MBS provides radio coverage restricted to a small area (e.g. sports arena, factory, television studio) and supports communications between MBS mobile terminals and terminals directly connected to the B-ISDN at up to 155 Mbit/s.

MBWA: Mobile Broadband Wireless Access
Mobile Broadband Wireless Access (MBWA), nicknamed as Mobile-Fi, is an IEEE standard defined by the 802.20 group to define the interface that allows the creation of low-cost, always-on, and truly mobile broadband wireless networks. The scope of the MBWA standard consists of the physical (PHY), medium access control (MAC), and logical link control (LLC) layers. The air interface will operate in bands below 3.5 GHz and with a peak data rate of over 1 Mbit/s.
MC-CDMA, also called CDMA2000, typically means the combination of three IS-95 carriers to form one wideband carrier. It is an evolution of IS-95 for third generation systems.

MCD: Mobile Computing Device
Mobile Computing Devices (MCD) are the computer devices such as notebook that can access to the network through mobile access.
Mcps: Mega Chips Per Second
Mega Chips Per Second (Mcps) is a measure of the number of bits (chips) per second in the spreading sequence of direct sequence spreading code.

MDA: Microconnect Distributed Antennae
Microconnect Distributed Antennae (MDA) are small-cell local area (200--300 metre range) transmitter-receivers usually fitted to lampposts and other street furniture in order to provide Wireless LAN, GSM and GPRS connectivity. They are therefore less obtrusive than the usual masts and antennae used for these purposes and meet with less public opposition. Each antenna point contains a 63-65 GHz wireless unit alongside a large memory store providing proxy and cache services.
MDSS: Mobile Data Synchronization Service
Mobile Data Synchronization Service (MDSS) is the ability to synchronize data on client devices with data stored in an enterprise database. A common protocol has been developed that will eventually allow a variety of clients to synchronize with a variety of databases.

MED: Message Entry Device
Message Entry Device (MED) is a device which sends information into a paging network using TDP. This may be any type of device from a hand-held type of unit to a host computer.
MexE: Mobile Station Application Execution Environment
Mobile Station Application Execution Environment (MexE) is a framework to ensure a predictable environment for third-party applications in GSM or UMTS handsets. MExE does this by defining different technology requirements called "classmarks." MExE classmark 1 is based on WAP, classmark 2 on PersonalJava and JavaPhone, and classmark 3 on J2ME CLDC and MIDP. Other classmarks may be defined in the future. MExE specifies additional requirements for all classmarks, for instance, a security environment, capability and content negotiation, a user profile, user interface personalization, management of services and virtual home environment. A handset can support multiple classmarks.

MFN: Multi-Frequency Network
A Multi-Frequency Network (MFN) is a type of radio network that operates several transmitters on a number of different frequencies.
MGCF: Media Gateway Control Function
Media Gateway Control Function (MGCF), a component in the IP Multimedia Subsystem (IMS), communicates with the Call Session Control Function (CSCF) and controls the connections for media channels in an IMS-MGW. It performs protocol conversion between ISDN User Part (ISUP) and the IMS call-control protocols.

MHS: Message Handling System
Message Handling System (MHS) is a general-purpose system used for receiving, storing, and sending messages with a consistent set of protocols to connect to external devices.
MHz: Megahertz
MHz or Megahertz, in which one MHz is equal to one million Hertz, is a measurement of frequency.

Microbrowser is a modified Web browser that allows users to get Internet data on a handheld wireless device
Microcell is a very small cell used in densely populated areas where traffic volume is high. There is no official definition of what cell radius distinguishes a small cell from a microcell.

Microwave is the electromagnetic waves in the frequency range of 1 to 30 GHz. Microwave-based networks are an evolving technology gaining favor due to high bandwidth and relatively low cost.
MIDP: Mobile Information Device Profile
Mobile Information Device Profile (MIDP) is a set of Java APIs that is generally implemented on the Connected Limited Device Configuration (CLDC). It provides a basic J2ME application runtime environment targeted at mobile information devices, such as mobile phones and two-way pagers. The MIDP specification addresses such issues as user interface, persistent storage, networking, and application model.

MIMO: Multiple Input Multiple Output
Multiple Input Multiple Output (MIMO) refers to using multiple antennas in a Wi-Fi device to improve performance and throughput. The MIMO technology takes advantage of a characteristic called multipath, which occurs when a radio transmission starts out at point A and then reflects off or passes through surfaces or objects before arriving, via multiple paths, at point B. MIMO technology uses multiple antennas to collect and organize signals arriving via these paths. The technology is included the 802.11n standard.
MIN: Mobile Identification Number
Mobile Identification Number (MIN) is a unique identification number given to a mobile unit. In most cases, this number is the telephone number of the handset. In the case of analog cellular, the MIN is used to route the call. In most second generation system, the system assigns temporary numbers to the handset to route calls as a security precaution. See also TMSI.

MISO: Multiple Input, Single Output
Multiple Input Single Output (MISO) is a smart antenna technology that uses multiple transmitters and a single receiver on a wireless device to improve the transmission distance. MISO technology can be applied in areas such as Digital TeleVision (DTV), Wireless Local Area Networks (WLANs), Metropolitan Area Networks (MANs), and mobile communications. The implementation of MISO would include multiple antennas at the source, or transmitter, and the destination, or receiver, has only one antenna -- the antennas are combined to minimize errors and optimize data speed. Other forms of smart antenna technology include Multiple Input Multiple Output (MIMO) and Single Input Multiple Output (SIMO).
m-law companding
M-law companding is a type of non-linear (logarithmic) quantizing, companding and encoding techniques for speech signals based on the m-law. This type of companding uses a m factor of 255 and is optimized to provide a good signal-to-quantizing noise ratio over a wide dynamic range.

MLD: Maximum Likelyhood Detection
Maximum Likelyhood Detection (MLD) is an optimal scheme for detecting the spatially multiplexed signals in a mobile network.
MMDS: Multichannel Multipoint Distribution Service
Multichannel multipoint distribution service (MMDS), also known wireless cable, is a wireless telecommunications technology, used for general-purpose broadband networkings or, more commonly, as an alternative method of cable television programming reception. MMDS is used usually in sparsely populated rural areas, where laying cables is not economically viable. The MMDS band uses microwave frequencies from 2 GHz to 3 GHz in range. Reception of MMDS-delivered television signals is done with a special rooftop microwave antenna and a set-top box for the television receiving the signals. The receiver box is very similar in appearance to an analog cable television receiver box.

MMM: Mobile Media Mode
Mobile Media Mode (MMM, also marked as WWW:MMM), is a marketing icon comprising a unifying industry-wide marketing symbol representing web-based mobile products and services.
MMR: Mobile Multihop Relay
Mobile Multihop Relay (MMR) refers to the concept of relaying user data and possibly control information between an MMR base station and an IEEE Standard 802.16 compliant mobile station through one or more relay stations. Licensed spectrum is used for relay. The purpose of enabling relay is to enhance coverage, range, and throughput and possibly capacity of an MMRBS and to enable very low power devices to participate in the network. The adjective "mobile" used here refers to the fact that both mobile subscriber stations and mobile relay stations are supported. It is possible to establish multiple communications paths between the MMR-BS and an MS and to communicate the same user data and/or control/management information through both paths to improve communications reliability.

MMR-BS: MMR Base Station
Mobile Multihop Relay Base Station (MMR-BS) refers to a base station that is compliant with amendments IEEE 802.16j through IEEE 802.16e-2005, which has extended functionality to support MMR as defined in 802.16j. An MMR-BS is fully compliant with IEEE Standard 802.16e-2005 and has been enhanced by amendment IEEE 802.16j to support mobile multihop relay. Mobile multihop relay is supported only for the OFDMA mode of IEEE Standard 802.16e-2005. Relay stations that support a particular MMR-BS are managed by that MMR-BS.
MMS: Multimedia Messaging Service
Multimedia Messaging Service (MMS) allows users to send messages containing text, pictures, sounds, and other rich media between cell phones.

MMSE: Minimum Mean Squared Error
Minimum mean-square error (MMSE) relates to an estimator having estimates with the minimum mean squared error possible. MMSE estimators are commonly described as optimal.
Mobile Data service
Mobile data service is a personal communications service that is expected to provide two-way wireless communication of text, voice messages, and potentially video messages among computers, personal digital assistants, and databases. Mobile data services can be provided by a number of technologies such as cellular, Personal Telecommunications Services, mobile satellite, and Enhanced Specialized Mobile Radio, as well as networks.

Mobile IP
Mobile IP is the key protocol to enable mobile computing and networking, which brings together two of the world's most powerful technologies -- the Internet and mobile communication. In Mobile IP, two IP addresses are provided for each computer: home IP address which is fixed and care-of IP address which is changing as the computer moves. When the mobile moves to a new location, it must send its new address to an agent at home so that the agent can tunnel all communications to its new address timely.
Mobile phone network
Mobile phone network is a network of cells. Each cell is served by a radio base station from where calls are forwarded to and received from your mobile phone by wireless radio signals.

Mobile Satellite
Mobile Satellite is a personal communications service that is anticipated to provide two-way voice and data communications using satellites, handheld phones, and wireless modems incorporated into devices such as notebook computers. It is expected that Mobile Satellite services will offer enhanced features such as call waiting and voice mail. Geographic service coverage is anticipated to be larger than most PCS services and may be worldwide.
Mobile Station
Mobile Station (MS) refers generically to any mobile device, such as a mobile handset or computer, that is used to access network services. GPRS networks support three classes of mobile station, which describe the type of operation supported within the GPRS and the GSM mobile wireless networks. For example, a Class A MS supports simultaneous operation of GPRS and GSM services.

Mobile WiMAX
Mobile WiMax refers to the technologies defined in the IEEE 802.16e (formally known as 802.16-2005), which addresses mobility of wireless broadband (WiMax). 802.16e, based on an existing WiMax standard 802.16a, adds WiMax mobility in the 2 to 6 GHz licensed bands. provides an improvement on the modulation schemes stipulated in the original (fixed) WiMAX standard. Mobile WiMax allows for fixed wireless and mobile Non Line of Sight (NLOS) applications primarily by enhancing the OFDMA (Orthogonal Frequency Division Multiple Access).
Modulate refers to varying the amplitude, frequency or phase of a radio signal in order to transmit information.

Modulation refers to carring information on a signal by varying one or more of the signal's basic characteristics -- frequency, amplitude and phase. Different modulation carries the information as the change from the immediately preceding state rather than the absolute state.
MOS: Mean Opinion Score
Mean Opinion Score (MOS) is a statistical rating and scoring technique used to rate the performance of telephone connections by users.

MPE: Multi-Pulse Excited
Multi-Pulse Excited (MPE) is a multi-pulse process for determining the position and amplitude of sample pulses in a speech codec.
MRFC: Multimedia Resource Function Controller
Multimedia Resource Function Controller (MRFC), a component in the IP Multimedia Subsystem (IMS), is the element responsible for taking SIP requests from the Application Server (AS) and translating them to messages that control the media processing resources residing in the Multimedia Resource Function Processor (MRFP).

MRFP: Multimedia Resource Function Processor
Multimedia Resource Function Processor (MRFP) is a component in the IP Multimedia Subsystem (IMS). The mixing of the various conference participants media streams is performed by the MRF (Media Resource Function) which comprises of the MRFC (Media Resource Function Controller) and the MRFP (Media Resource Function Processor). MRFP is where the actual media processing resources reside.
MRS: Mobile Relay Station
Mobile Relay Station (MRS), a concept in the mobile WiMAX network, is a relay station that is intended to function while in motion. MRS mobility is constrained by the same limits as an Mobile Staton (MS) in IEEE Std 802.16e-2005. An MRS may be installed in a bus or train for use by IEEE Std 802.16-2005 subscribers.

MS: Mobile Station
Mobile Station refers to the customer terminal including hardware and software in a wireless network.
MSA: Metropolitan Statistical Area
Metropolitan Statistical Area (MSA) is a geographic area over which a cellular operator is licensed to provide service. MSAs are groups of counties in metropolitan areas having common financial, commercial and economic ties and were first used to license cellular service in the early '80s. MSAs cross state lines in some instances. MSAs were first used by the Dept.of Commerce to collect economic data.

MSB: Most Significant Bit
Most Significant Bit (MSB), in a binary coding scheme, is the bit having the greatest numerical value. Analogous to the left-most numeric position in a decimal number.
MSC: Mobile Switching Center
Mobile Switching Center (MSC) is the place that provides telephony switching services and controls calls between telephone and data systems. The MSC switches all calls between the mobile and the PSTN and other mobiles.

MSISDN: Mobile Station Integrated Services Digital Number
Mobile Station Integrated Services Digital Number (MSISDN), the mobile equivalent of ISDN, refers to the 15-digit number that is used to refer to a particular mobile station. The ITU-T recommendation E.164 defines the international numbering plan that MSISDN is based on. The acronym MSISDN has a number of different expansions when used to refer to the value: Mobile Subscriber ISDN Number, Mobile Station International Subscriber Directory Number, Mobile Station ISDN Number, amongst other variants.
MSK: Minimum Shift Keying
Minimum Shift Keying (MSK) is a modulation technique using sinusoidal shaped input data pulses to drive the phase modulator. This results in a linear phase change over conventional QPSK, resulting in lower side lobes and less adjacent channel interference performance.

MSO: Multi-Services Operator
Multi-Services Operator (MSO) is a service provider which provides multiple services such as voice (mobile and fixed line), data and vedio.
MSS: Mobile Satellite Service
Mobile satellite services (MSS) refers to the communications satellites network for mobile and portable wireless telephones services. There are three major types of MSS: AMSS (aeronautical MSS), LMSS (land MSS), and MMSS (maritime MSS).

MTA: Message Transfer Agent
Message Transfer Agent (MTA) is the portion of a Message Handling System (MHS) that deals with moving messages within the Message Handling System (MHS).
MTSO: Mobile Telephone Switching Office
Mobile Telephone Switching Office (MTSO), a computer or a switch, is the brains of a cellular system. The MTSO assigns frequencies to each call, reassigns frequencies for hand-offs, interconnects calls with the local and long distance landline telephone companies, compiles billing information, etc. Every cellular system has one or more MTSOs or switches.

Multichannel Multipoint Distribution Service
Multichannel multipoint distribution service is a broadcasting and communications service that operates in the ultra-high frequency (UHF) portion of the radio spectrum between 2.1 and 2.7 GHz. Multichannel multipoint distribution service is also known as wireless cable. It was conceived as a substitute for conventional cable television (TV). However, it also has applications in telephone/fax and data communications.
Multipath is a propagation phenomenon characterized by the arrival of multiple versions of the same signal from different locations shifted in time due to having taken different transmission paths of varying lengths.

Multiple access
Multiple access is the process of allowing multiple radio links or users to address the same radio channel on a coordinated basis. Typical multiple access technologies include FDMA, TDMA, CDMA, and FHMA.

NACN: North American Cellular Network
North American Cellular Network (NACN) is an organization of cellular providers that facilitates cellular calls across the country to be linked for seamless roaming.
NADS: North American Digital Standards
North American Digital Standards (NADS) refers to the North America cellular standards: the first generation is TDMA and has been in service since 1992. The second generation is CDMA which was accepted by the TIA2.48 as a standard in 1992. The third generation is CDMA2000 and more.

NAM: Number Assignment Module
Number Assignment Module (NAM) is the programmable module in an AMPS analog phone used to contain the MIN, ESN, home system ID and other information.
NAMPS: Narrowband Advanced Mobile Phone Service
Narrowband Advanced Mobile Phone Service (NAMPS) is an improved version of AMPS systems. NAMPS is a cellular call-handling system that uses digital signalling techniques to split the existing 30 kHz wideband voice channels into three 10 kHz narrowband voice channels. The result is three times more voice channel capacity than the traditional AMPS system provides. NAMPS cellular phones are manufactured for dual mode operation, and they are compatible with traditional AMPS systems.

NASS: Network Attachment Subsystem
The Network Attachment Subsystem (NASS), a component in the IP Multimedia Susbsystem (IMS), provides the following functionalities: (1) Dynamic provision of IP address and other user equipment configuration parameters (e.g. using DHCP). (2) User authentication, prior or during the IP address allocation procedure. (3) Authorisation of network access, based on user profile. (4) Access network configuration, based on user profile. (5) Location management.
Nationwide Paging
Nationwide Paging is a method of national or regional paging in which a single frequency is used throughout the nation (region) for sending messages to a paging system subscriber.

Nested codes
Nested codes is a type of concatenated block code where the layers (inner and outer) are amalgamated in such a way that burst errors -- not able to be corrected by the inner code -- are sufficiently spread over enough blocks as to be corrected by the outer layer.
NetStumbler is a freely available Windows utility for wireless LAN discovery. It is useful for site surveys, detecting rogue access points, and finding and mapping WLAN installations.

NFC: Near Field Communication
Near Field Communication (NFC) is a short-range wireless connectivity standard jointly developed by Philips and Sony that uses magnetic field induction to enable communications between devices when they're touched together, or brought within a few centimeters of each other. The standard specifies a way for the devices to establish a peer-to-peer (P2P) network to exchange data.
NLOS: Non Line of Sight
Non Line of Sight (NLOS), also known as near-line-of-sight or obstructed path/pathway, is a term used to describe radio transmission across a path that is partially obstructed, usually by a physical object in the Fresnel zone. Many types of radio transmissions depend, to varying degrees, on line of sight between the transmitter and receiver. Obstacles that commonly cause NLOS conditions include buildings, trees, hills, mountains, and, in some cases, high voltage electric power lines.

NMC: Network Management Center
Network Management Center (NMC) is an operations center used to manage network resources such as the MSC, location registers and base stations.
NMT: Nordic Mobile Telephony
Nordic Mobile Telephony (NMT) is the common Nordic standard for analog mobile telephony as established by the telecommunications administrations in Sweden, Norway, Finland and Denmark in the early 1980s. NMT systems have also been installed in some European countries, including parts of Russia, and in the Middle East and Asia. NMT is operated in 450 MHz and 900 MHz bands.

NMT-450: Nordic Mobile Telephony - 450
Nordic Mobile Telephony - 450 (NMT-450) is an early cellular system developed and operated in northern Europe utilizing the 450 MHz band.
Noise refers to any undesirable communication channel signals.

Noise figure
Noise figure is a figure of merit for receivers and preamplifiers representing the amount of excess noise added to the signal by the amplifier or receiving system itself. The lower the noise figure, the less excess noise is added to the signal.
NRS: Nomadic Relay Station
Nomadic Relay Station (NRS), a concept in the WiMAX network, is a relay station that is intended to function from a location that is fixed during periods of time comparable to that of a user session. An NRS is not permanently installed. An NRS may rely solely on battery power in some instances.

nrtPS: Non-Real-Time Polling Service
Non-Real-Time Polling Service (nrtPS) is one of the five QOS service types defined in the IEEE 802.16 WiMAX. The 802.16 protocol supports five types of QoS UGS (Unsolicited grant service), rtPS (Real time polling Service), ertPS (Extended Real-time POLLING SERVICE), nrtPS (Non-real-time polling service and BE (Best effort service). The Non-Real-Time Polling Service (nrtPS) is designed to support non real-time service flows that require variable size Data Grant Burst Types on a regular basis, such as high bandwidth FTP. The service offers unicast polls on a regular basis, which assures that the flow receives request opportunities even during network congestion.
NRZ: Non Return to Zero
Non Return to Zero (NRZ) is a type of data stream where successive data pulses "ones" are continuous over several clock cycles without returning to the "zero" state between successive "ones".

NSS: Network Switching Subsystem
Network Switching Subsystem is a portion of a GSM network that manages the connections and communications within the network. The BSS and OSS complete the major components of the network.
Numeric Paging or alphanumeric-paging
Numeric Paging is the most widely used type of paging. The caller simply calls your pager phone number and enters the number where you can reach them. This number appears on the receiver's pager, and the receiver can call the sender. On the other hand, text paging allows callers to send the receiver a short message that you can act on immediately.

Nyquist filter
Nyquist filter is an ideal low pass filter with a cutoff frequency equal to the sampling rate. This technique is used to convert PAM pulses to an analog signal in D/A converters.
Nyquist rate
Nyquist rate is the minimum sampling rate proposed by Nyquist for converting a band limited waveform to digital pulses. The rate must be at least twice the highest frequency of interest in the waveform being sampled.

OBEX: OBject Exchange
OBject EXchange (OBEX or IrOBEX) is a communications protocol that facilitates the exchange of binary objects between devices. It is maintained by the Infrared Data Association but has also been adopted by the Bluetooth Special Interest Group and the SyncML wing of the OMA. One of OBEX's earliest popular applications was in the Palm III personal digital assistant. This PDA and its many successors use OBEX to exchange business cards, data, even applications.
OCQPSK: Orthogonal Complex Quadrature Phase Shift Keying
Orthogonal Complex Quadrature Phase Shift Keying (OCQPSK), also known as HPSK, is a digital modulation scheme that conveys data by changing, or modulating, the phase of a reference signal (the carrier wave).

OFDM: Orthogonal Frequency Division Multiplexing
Orthogonal Frequency Division Multiplexing (OFDM) is an FDM modulation technique for transmitting large amounts of digital data over a radio wave. OFDM works by splitting the radio signal into multiple smaller sub-signals that are then transmitted simultaneously at different frequencies to the receiver. 802.11a WLAN, 802.16 (WiMAX) technologies use OFDM as the physical layer communication standard.
OFDMA: Orthogonal Frequency Division Multiple Access
Orthogonal Frequency Division Multiple Access (OFDMA), also referred to as Multiuser-OFDM, is being considered as a modulation and multiple access method for 4th generation wireless networks. OFDMA is an extension of Orthogonal Frequency Division Multiplexing (OFDM), which is currently the modulation of choice for high speed data access systems such as IEEE 802.11a/g wireless LAN (WiFi) and IEEE 802.16a/d/e wireless broadband access systems (WiMAX).

OHG: Operators Harmonization Group
Operators Harmonization Group (OHG) is a group of industry operators established to meet on harmonization issues. The group is working towards a way of harmonisation between CDMA2000 and W-CDMA.
Okamura model
Okamura model is a propagation prediction model for land-mobile communications developed by Yoshi Okamuar et al. in the late 1960s.

OMA: Open Mobile Alliance
Open Mobile Alliance (OMA) is the leading industry forum for developing market-driven, interoperable mobile service enablers. OMA was formed in June, 2002, by nearly 200 companies including the world's leading mobile operators, device and network suppliers, information technology companies and content and service providers. The fact that the whole value chain is represented in OMA marks a change in the way specifications for mobile services are done.
OMC: Operations & Maintenance Center
Operations & Maintenance Center (OMC) is a location used to operate and maintain a wireless network.

OQPSK: Offset Quadrature Phase Shift Keying
Offset Quadrature Phase Shift Keying (OQPSK), sometimes called Staggered QPSK (SQPSK), is a type of QPSK modulation that offsets the bit streams on the I and Q channels by a half bit. This reduces amplitude fluctuations and helps improve spectral efficiency. In other words, using OQPSK increases the temporal efficiency of normal QPSK.
ORFS: Output Radio Frequency Spectrum
Output Radio Frequency Spectrum (ORFS) is a measurement for GSM signals that tests for interference in the adjacent frequency channels (ARFCNs) and results from two effects: modulation within the bursts and the power that ramps up and down, or switching transients. ORFS is a critical GSM transmitter measurement.

OSA: Open System Architecture
Open System Architecture (OSA) is part of the 3rd generation (3G) UMTS mobile telecommunications network. OSA describes how services are architected in a UMTS network. The OSA provides APIs to access the network functions like authentication and authorization of the user. The APIs are guaranteed to be secure, independent of vendor specific solutions and also independent of programming language by use of Object Oriented techniques like CORBA, SOAP etc. Various services like VPN, conferencing and many more unknown services can be implemented with the help of these APIs. The standards for OSA are being developed as part of the 3rd Generation Partnership Project (3GPP).
OVSF: Orthogonal Variable Spreading Function
Orthogonal Variable Spreading Function (OVSF) is a set of spreading codes derived from tree-structured set of orthogonal codes and are used to channelize the IMT-2000/ULTRA system.

PA: Power Amplifier
Power Amplifier (PA) is a device for taking a low or intermediate-level signal and significantly boosting its power level. A power amplifier is usually the final stage of amplification in a transmitter.
Packet Radio
Packet radio is a form of digital data transmission used in amateur radio to construct wireless computer networks. Its name is a reference to the use of packet switching between network nodes, which allows multiple virtual circuits to coexist on a single radio channel. Packet radio networks use the AX.25 data link layer protocol, derived from the X.25 protocol suite and designed for amateur radio use.

PACS: Personal Access Communications System
Personal Access Communications System (PACS) is a low mobility low power wireless system designed for residential use.
Paging refers to deliver a message to someone when their location is unknown through a wireless device usually known as a pager.

PAM: Pulse Amplitude Modulation
Pulse Amplitude Modulation (PAM) is a form of signal modulation in which the data is encoded in the amplitude of a series, or train, of regularly recurrent signal pulses. PAM is used less frequently than PCM (Pulse-Code Modulation).
PAN: Personal Area Network
A personal area network (PAN) is a computer network used for communications among computer devices (including telephones and personal digital assistants) close to one person within a few meters. PAN allows devices to work together and share information and services. Using Bluetooth wireless technology, Personal Area Networks can be created in public places, in your home, in your office, and even in your car. This network enables everyday devices to become smart, tetherless devices--working and communicating together. For example, it offers the ability to wirelessly synchronize with your desktop to access your e-mail and Internet/intranet from remote locations.

Panel Antenna
Panel Antenna is an antenna type that radiates in only a specific direction. Panel antennas are commonly used for point-to-point situations. You may also see them called "patch antennas."Parabolic Antenna Parabolic Antenna is an antenna type that radiates a very narrow beam in a specific direction. Parabolic antennas offer the highest gain for long-range point-to-point situations.
Paring is the process of engaging two Bluetooth devices to each other so they can communicate.

Parity is a simple error detection scheme. The method usually involves counting the '1' bits in a codeword and then setting an additional bit to either '1' or '0' depending on whether the original number of '1' bits was even or odd.
Partial Response Signalling
Partial Response Signalling is a signalling technique in which a controlled amount of intersymbol interference is introduced at the transmitter to shape the transmitted spectrum.

Passphrase, also called password, is the words you must enter to authenticate both sides of the connection when pairing Bluetooth devices. More generically, you may see passphrase used in place of "password" to indicate that you can enter more than a single word.
Path loss
Path loss is the amount of loss introduced by the propagation environment between a transmitter and receiver. Power loss that occurs when RF waves are transmitted through the air. This loss occurs because the atmosphere provides a filtering effect to the signal. Certain electromagnetic frequencies (very high and non-commercial) are completely blocked or filtered by the atmosphere.

PCH: Paging Channel
Paging Channel (PCH), used primarily to notify the mobile that it has an incoming call, is a logical channel in GSM, cdma2000, and W-CDMA systems used to send messages to mobile station.
PCIA: Personal Communications Industry Association
Personal Communications Industry Association (PCIA) is a trade group representing PCS, SMR, private radio and other wireless users and carriers.

PCIA: Personal Communications Industry Association
Personal Communications Industry Association (PCIA) is an international trade association representing the personal communications services (PCS), private radio and other wireless users and carriers. Its primary objective is to advance regulatory policies, legislation, and technical standards in this industry.
PCM: Pulse Code Modulation
Pulse Code Modulation (PCM) is the most predominant type of digital modulation in use today. PCM performs an analog to digital conversion of the speech waveform through a sampling process and encodes and transmits the samples in a serial bit stream as 8-bit digital words.

PCMCIA: Personal Computer Memory Card International Association
Personal Computer Memory Card International Association (PCMCIA) has defined a standardized technology used to develop a expansion for portable devices (i.e.. notebooks) In paging these credit card sized devices support wireless connectivity.
PCN: Personal Communications Network
Personal Communications Network (PCN) is a standard for digital mobile phone transmissions operating at a frequency of 1800 MHz (also referred to as GSM 1800). It is used in Europe and Asia Pacific.

PCS: Personal Communication Service
Personal Communication Service (PCS) describes a wide variety of two-way digital wireless service offerings in North America operating at 1900 MHz. PCS services include next generation wireless phone and communication services, wireless local loop, inexpensive walk-around communications service with lightweight, low-powered handsets, in-building cordless voice services for business, in-building wireless LAN service for business, enhanced paging service as well as wireless services integrated with wired networks. A Personal Communications System refers to the hardware and software that provide communications services.
PCU: Packet Control Unit
The Packet Control Unit (PCU) is a late addition to the GSM standard. It performs some of the processing tasks of the Base Station Controller (BSC), but for packet data. The allocation of channels between voice and data is controlled by the base station, but once a channel is allocated to the PCU, the PCU takes full control over that channel. The PCU can be built into the base station, built into the BSC, or even in some proposed architectures, it can be at the SGSN site.

PDA: Personal Digital Assistant
Personal Digital Assistant (PDA) is a small, handheld wireless device for transmitting pages, data messages, faxes and emails. It also acts as an electronic organizer, giving you access to schedules and contact lists. The term is often used interchangeably with PIM (personal information manager). The 3Com PalmPilot is an example of a PDA or PIM.
PDC: Personal Digital Cellular
Personal Digital Cellular (PDC) is a TDMA-based 2G mobile phone standard developed and used exclusively in Japan. PDC uses 25 kHz carrier, 3 time slots, pi/4-DQPSK modulation and low bit-rate 11.2 kbit/s and 5.6 kbit/s (half-rate) voice codecs. PDC is implemented in the 800 MHz (downlink 810-888 MHz, uplink 893-958 MHz), and 1.5 GHz (downlink 1477-1501 MHz, uplink 1429-1453 MHz) bands. The air interface is defined in RCR STD-27 and the core network MAP by JJ-70.10.

PDCP: Packet Data Convergence Protocol
Packet Data Convergence Protocol (PDCP) is used in UMTS 3G network to map higher-level protocol characteristics onto the characteristics of the underlying radio-interface protocols, providing protocol transparency for higher-layer protocols. PDCP also provides protocol control information compression.
PDF: Probability Density Function
In mathematics, a probability density function (pdf) represents a probability distribution in terms of integrals. Informally, a probability density function can be seen as a "smoothed out" version of a histogram: if one empirically measures values of a continuous random variable repeatedly and produces a histogram depicting relative frequencies of output ranges, then this histogram will resemble the random variable's probability density.

PDF: Policy Decision Function
Policy Decision Function (PDF), a component in the IP Multimedia Subsystem (IMS), controls traffic entering the packet-switched network by allocating or denying IP bearer resources.
PDP Context
Packet data protocol (PDP) context is a term used in the mobile wireless network indicating a logical association between an MS (Mobile Station) and PDN (Public Data Network) running across a GPRS network. The context defines aspects such as Routing, QoS (Quality of Service), Security, Billing etc.

Peak power
Peak power is the maximum instantaneous power radiated by a pulsed or bursted transmitter. It is the power radiated while the transmitter is keyed or operated.
PER: Packed Encoding Rules
Packed Encoding Rules (PER) is a set of rules that specifies how ASN.1-defined information is encoded when transmitted, and how it is decoded when received. PER is a successor to the Basic Encoding Rules (BER). It is more efficient in terms of the number of bytes transmitted and the size of the generated encoder and decoder.

PFS: Proportional Fair Scheduling
Proportional Fair Scheduling (PFS) is a scheme for wireless communication for both a single antenna system and multiple transmit and receive antennas. The Proportional Fair algorithm is an algorithm that schedules the channel for the station that has the maximum of the priority function, where T denotes the data rate potentially achievable for the station at the present moment (in the present time slot), R is the average data rate of this station. Parameters α and β tune the fairness of the scheduler, that is, is it fair to all stations giving them equal bandwidth or is the scheduler maximizing the throughput of the channel.
Generally speaking, phase is the current position in the cycle of something that changes cyclically.

Phase jitter
Phase jitter is the amount of uncertainty introduced in digital demodulation caused by the rapid fluctuation of the frequency of the transmitted signal, typically due to imperfections in the clock recovery timing.
PHP: Personal Handy Phone
Personal Handy Phone (PHP) is the mobile handset used with the Japanese Personal Handy Phone system.

PHS: Personal HandyPhone System
Personal HandyPhone System (PHS) was developed in Japan as a cordless telecommunication system operating within the band 1895MHz to 1918MHz. PHS is a lightweight portable wireless telephone that functions as a cordless phone at home and as a mobile phone elsewhere. The Personal Handyphone also handles voice, fax, and video signals.
Physical channel
Physical channel is the actual radio channel that carries the various logical and traffic channels in a wireless system.

Pico cell
Pico cell is a very small cell in a mobile network for boosting capacity within buildings.
Pilot code
Pilot code is a logical channel in a CDMA system characterized by an unmodulated direct sequence spread-spectrum signal continuously monitored by each base station. It allows the mobile stations to acquire the timing of the forward channel, serves as a phase reference for demodulation, and allows the mobile to search out the best (strongest) base stations for acquisition and hand-off.

Pilot pollution
Pilot pollution is a type of co-channel interference in CDMA systems caused when the pilot code from a distant cell or base station is powerful enough to create an interference problem.
PIN: Personal Identification Number
Personal Identification Number (PIN) is a code used for all GSM-based phones to establish authorization for access to certain functions or information. The PIN code is delivered together with your subscription.

PLL: Phase Locked Loop
Phase Locked Loop (PLL) is a major component in the frequency synthesizer scheme. This device provides a wide, flexible range of internal frequency dividers which allow the designer the ability to create a synthesizer to match design requirements.
PLMN: Public Land-Mobile Network
Public Land-Mobile Network (PLMN) is a European term used to describe all mobile wireless networks that use earth-based stations rather than satellites. PLMN is the mobile equivalent of the PSTN.

Phase Modulation
Phase Modulation (PM) is the scheme of modulation that the phase of the carrier signal is modulated in accordance with the message signalPMP: Paging Message ProcessorPaging Message Processor (PMP) is a Radio Paging Terminal or equivalent message processing system.
PMR: Private Mobile Radio
Private Mobile Radio (PMR) is for use within a defined user group such as the emergency services or by the employees of a mining project.

PN: Pseudo-Noise
Pseudo-Noise (PN), also known as pseudorandom noise (PRN), is a signal similar to noise which satisfies one or more of the standard tests for statistical randomness. Although it seems to lack any definite pattern, pseudorandom noise consists of a deterministic sequence of pulses that will repeat itself after its period.
PNCQPSK: Pseudo-Noise Complex Quadrature Phase Shift Keying
Pseudo-Noise Complex Quadrature Phase Shift Keying (PNCQPSK) is the spreading technique that uses basic complex scrambling and Pseudo-Noise (PN) signals for Is and Qs. PNCQPSK is used in 3G mobile wireless technologies.

POCSAG: Post Office Code Standard Advisory Group
Post Office Code Standard Advisory Group (POCSAG), also known as RPC1 (a CCIR standard taken directly from POCSAG), is a group formed by the British Post Office to design a non-proprietary digital paging code. The code that they designed is now implemented by most pager manufacturers and is the most widely used code to date. The POCSAG code can be operated at three speeds, 512, 1200, and 2400 bits per second. POCSAG is gradually being replaced by FLEX.
PoC: Push to Talk over Cellular
Push To Talk Over Cellular (PoC) is a walkie-talkie type service provided over a cellular phone network. A push to talk over a cellular system typically supports telephony services. There are proprietary implementations, and the Open Mobile Alliance defines standards for PoC. Push to talk calls are half duplex communications -- while one person speaks, the other(s) listen. A push-to-talk connection is typically connected virtually instantaneously. A single press reaches an active talk group. Users no longer need to make several calls to coordinate with a group.

Polarization diversity
Polarization diversity is a diversity technique where antennas of different polarizations, i.e., horizontal and vertical, are used to provide diversity reception. The antennas take advantage of the multipath propagation characteristics to receive separate uncorrelated signals.
Power control
Power control is a technique for managing the transmit power in base stations and mobiles to a minimum level needed for proper performance. Downlink power control applies to base stations and uplink power control to mobiles. Power control is used in nearly all wireless systems to manage interference, and in the case of mobiles, to extend battery life.

PQA: Palm Query Applications
Palm Query Applications (PQA) is an Internet clipping application developed from HTML code and run on Palm PDAs. The application is designed to streamline the flow to the PDA to minimize the number of kilobytes sent and ultimately paid for.
PRBS: Pseudo-Random Binary Sequence
Pseudo-Random Binary Sequence (PRBS), commonly used to performance test PCM systems, is a digital signal having framing information and using pseudo-noise in the individual traffic channels.

PRMA: Packet Reservation Multiple Access
Packet Reservation Multiple Access (PRMA) is a packet-based TDMA concept where the users contend for the time slots. In situations where the system is not near capacity, a user can reserve a time slot for future uses.
Processing gain
Processing gain is the amount of gain, in dB, provided by the spreading code in a CDMA system, usually the ratio of the spreading rate to the information rate.

Propagation is the process an electromagnetic wave undergoes as it is radiated from the antenna and spreads out across the physical terrain. See also propagation channel.
Propagation channel
Propagation channel is the physical medium electromagnetic wave propagation between the transmit and receive antennas, and includes everything that influences the propagation between the two antennas.

PSD: Power spectral density
Power spectral density (PSD) refers to the amount of power per unit (density) of frequency (spectral) as a function of the frequency. The power spectral density, PSD, describes how the power (or variance) of a time series is distributed with frequency. By knowing the power spectral density and system bandwidth, the total power can be calculated.
PSK: Phase Shift Keying
Phase Shift Keying (PSK) is a broad classification of modulation techniques where the information to be transmitted is contained in the phase of the carrier wave.

PSTN: Public Switched Telephone Network
Public Switched Telephone Network (PSTN) is the network of the world's public circuit-switched telephone networks, providing commercial telephony services. Originally as a network of fixed-line analog telephone systems, the PSTN is now almost entirely digital and includes mobile as well as fixed telephones.
PTT: Post, Telecommunications&Telegraph
Post, Telecommunications&Telegraph (PTT) is typically the Ministry of Post, Telecommunications and Telegraph. It is also a term to describe the incumbent, dominant operator in a country, many of which are being or have been privatized.

Punctured code
Punctured code is a technique used in convolutional decoders that allows a limited number of coded bits to be deleted to greatly simplify processing in the codec. This is extremely useful with long codes.
PUSC: Partially Used Sub-Carrier
Partially Used Sub-Carrier (PUSC), sometimes called Partially Used Sub-Channel, was first defined in the IEEE802.16d (Fixied WiMAX) for the OFDMA PHY layer. Basically, the IEEE802.16e (Mobile WiMAX) uses the same OFDMA sub-channelization structure and its extension to address mobility has retained the OFDMA concept for FUSC (Fully Used Sub-carrier) and PUSC. Use of FUSC, mainly in the DownLink, and PUSC in both DL and UL as defined in 16d or 16e with Reuse 1 will endow the WRAN system with the needed capability and flexibility to configure the WRAN in different scenarios with manageable interference among the Base Stations where different Service Providers may deploy the system in the same region using the same free TV channel.

QAM: Quadrature Amplitude Modulation
Quadrature Amplitude Modulation (QAM) is a type of modulation where the signalling information is carried in the phase and amplitude of the modulated carrier wave. Specifically for QAM, the amplitude of two waves, 90 degrees out-of-phase with each other (in quadrature) are changed (modulated or keyed) to represent the data signal, in which each combination of phase and amplitude represents one of sixteen four-bit patterns.
Q-Band, also known as V-Band, is a radio bandwidth range between 40 GHz t0 50 GHz.

QCIF: Quarter CIF
Quarter CIF (QCIF) is a video image format which employs 176 horizontal pixels and 144 vertical lines. Although resolution is courser than CIF, QCIF consumes less memory while still achieving an acceptable level of clarity on small displays such as those incorporated in mobile phones.
QPSK: Quadrature Phase Shift Keying
Quadrature Phase Shift Keying (QPSK) is a digital modulation scheme that conveys data by changing, or modulating, the phase of a reference signal (the carrier wave). Sometimes known as quaternary or quadriphase PSK or 4-PSK, QPSK uses four points on the constellation diagram, equispaced around a circle. With four phases, QPSK can encode two bits per symbol, shown in the diagram with Gray coding to minimize the BER.

The quadrature phase channel in a phase shift keyed system having more that 2 phase states.
Quantizing is the process of assigning values to waveform samples by comparing the samples to discrete steps.

RAB: Reverse-Link Activity Bit
Reverse-Link Activity Bit (RAB) is for determining the data rate of a reverse link communication of a mobile communication system. A processor in the access terminal may determine whether the access terminal is in an idle mode, and passing a non-busy state value of the RAB to the digital filter when the access terminal is in the idle mode. The RAB may be compared to a threshold to determine a mode of reverse link data rate determination. The mode defines a set of criteria for an aggressiveness level of increasing or decreasing the reverse link communication data rate. The processor, therefore, determines the data rate based on the filtered reverse activity bit in accordance with the determined mode.
RACE:Research in Advanced Communications Equipment
Research in Advanced Communications Equipment (RACE) is an ETSI research project that has subsequently been replaced by ACTS.

RACH: Random Access Channel
Random Access Channel (RACH) is the channel used by mobiles in GSM and W-CDMA systems to gain access to the system when first attaching to it.
Radio is the electromagnetic waves whose frequencies are below 3,000 GHz as defined in Article 2 of the Radio Law in general. However, in practice, radio is generally refered to as electromagnetic waves whose frequencies are between 10 kHz and 300 GHz.

Radio link
Radio link refers to the equipment and transmission path (propagation channel) used to carry on communications. It includes the transmitting system, the propagation channel and receiving system.
Radio port
Radio port is a unit that supports transmission of signals over the air interface.

Radio propagation
Radio propagation refers to the electromagnetic waves at radio frequencies as they radiate from a transmitting antenna.
Rake receiver
Rake receiver is a radio receiver having multiple "fingers" and utilizing off-sets of a common spreading code to receive and combine several multipath (time delayed) signals, in effect using "time diversity" to overcome deep fades.

RAN: Radio Access Network
Radio Access Network (RAN) is the ground-based infrastructure required for delivery of third-generation (3G) wireless communications services, including high-speed mobile access to the Internet. The RAN must be able to manage a wide range of tasks for each 3G user, including access, roaming, transparent connection to the public switched telephone network and the Internet, and Quality of Service (QoS) management for data and Web connections.
RANAP: Radio Access Network Application Part
Radio Access Network Application Part (RANAP) is the Radio Network Layer signaling protocol used in a UMTS system on the Iu interface. It is responsible for functions including the setting up of a RAB (Radio Access Bearer) between the CN (Core Network) and the RNC (Radio Network Controller).

Random access
Random access is a technique for radio access to a network where an access message is not coordinated or administered by the network and can collide with other attempts by others to access the network over the same channel.
Rayleigh channel
Rayleigh channel is a communications channel having a fading envelope in the form of the Rayleigh Probability Density Function.

Rayleigh fading
Rayleigh fading is a type of signal fading caused by independent multipath signals having a Rayleigh PDF.
RBDS: Radio Broadcast Data System
Radio Broadcast Data System (RBDC), an replacement of Emergency Braodcast System, allows radio stations to send text messages, such as emergency warning and traffic alerts to radios installed with special display screens.

RC: Radio Configuration
Radio Configuration (RC) defines the physical channel configuration of cdma2000 (IS-2000) signals. Each RC specifies a set of data rates based on either 9.6 or 14.4 kbps. RC1 is the backwards-compatible mode of cdmaOne for 9.6 kbps voice traffic. It includes 9.6, 4.8, 2.4, 1.2 kbps data rates and operates at Spread Rate 1 (SR1). RC3 is a cdma2000 specific configuration based on 9.6 kbps that also supports 4.8, 2.7, and 1.5 kbps for voice, while supporting data at 19.2, 38.4, 76.8, and 153.6 kbps. RC3 also operates at SR1.
RCC: Radio Common Carrier
Radio Common Carrier (RCC) refers to a service provider for public mobile service.

RDCCH: Reverse Digital Control Channel
Reverse Digital Control CHannel (RDCCH), defined in the IS-136, is for the upstream signaling and control information from user equipment to cell site in a TDMA-based system. RDCCH works together with FDCCH which provides the downstream signaling and control information in such a system.
REAG Region
REAG Region is a geographic area over which a WCS operator is licensed to provide service. REAGs are a group of economic areas (EAs) and were first used to license WCS service in the late 1990s. REAGs are very large, with 6 REAGs covering the entire continental United States.

Receive diversity
Receive diversity is the process of providing two independent receiving systems and spatially separated antennas to overcome fading effects on the radio signal.
Receiver is a device on a transmission path which converts the signals as received from the transmission system into the signals required by the destination equipment.

Reed Solomon code
Reed-Solomon codes are block-based error correcting codes with a wide range of applications in digital communications and storage. Reed-Solomon codes are used to correct errors in many systems including: (1) Storage devices (including tape, Compact Disk, DVD, barcodes, etc) (2) Wireless or mobile communications (including cellular telephones, microwave links, etc) (3) Satellite communications. (4) Digital television / DVB. (5) High-speed modems such as ADSL, cDSL, etc.
Reflection is a process that occurs when a propagating electromagnetic wave impinges upon a obstruction whose dimensions are very large when compared to the wavelength. Reflections from the surface of the earth and from buildings or walls produce reflected waves which may interfere,constructively or destructively at the receiver.

ReFLEX is a two-way paging protocols developed by Motorola for enhanced paging services. ReFLEX 25 supports outbound transfer rates of up to 6,400 bits per second in a 25 kHz channel and 12,800 bits per second in a 50 kHz channel.
Registration, in mobile wireless, is the process by which a mobile station informs the immediate service provider of its presence in the network and its desire to receive service.

Remote Access Point
Remote Access Point, also known as relay access points, is one of a number of secondary access points in a wireless network that uses Wireless Distribution System (WDS) to extend its range. Remote access points connect to a master access point.
Repeater, also known as network repeater, is a type of network device that regenerates incoming electrical, wireless or optical signals. With physical media like Ethernet or Wi-Fi, data transmissions can only span a limited distance before the quality of the signal degrades. Repeaters attempt to preserve signal integrity and extend the distance over which data can safely travel. Active hubs are repeaters. In Wi-Fi, access points function as repeaters when operating in so-called "repeater mode." In moble wireless, repeater receives radio signals from the base station and then amplified and retransmitted to areas where radio shadow occurs, and vice versa.

Reuse factor
Reuse factor, also known as frequency reuse factor, is the number of distinct frequency sets used per cluster of cells.
Reverse link
In radio communications, the reverse link, also known as return link, is the link from a mobile user to a fixed base station. If the link includes a communications relay satellite, the reverse link will consist of both an uplink (mobile station to satellite) and a downlink (satellite to base station).

RF: Radio Frequency
Radio Frequency generally refers to wireless communications with frequencies below 300 GHz. Formally, according to the Article 2 of th Radio Law, radio frequency is below 3,000 GHz. Radio frequencies can be used for communications between a mobile telephone and an antenna mast.
RF License: Radio Frequency License
Radio Frequency (RF) License is the purchased right to transmit RF waves over a given BTA for typically periods of 10 years. The license tightly governs the design parameters of an RF system and its use. RF licenses typically are purchased from the government (FCC in the US) on an auction basis. The government (FCC) provides licenses to ensure maximum competition in a free market and spectral efficiency, which is another way of stating efficient use of the RF spectrum.

RFCOMM: Radio Frequency Communication
Radio Frequency Communication (RFCOMM) is a Bluetooth protocol which is a simple set of transport protocols, providing emulated RS232 serial ports (up to sixty simultaneous connections of a bluetooth device at a time). RFCOMM is sometimes called Serial Port Emulation. The Bluetooth Serial Port Profile is based on this protocol.
RFI: Radio Frequency Interference
Radio Frequency Interference (RFI) refers to the noise caused by other Radio Frequency that interferes with information being transmitted across unshielded copper cable.

RFID: Radio frequency identification
Radio frequency identification (RFID) is a system for tagging and identifying mobile objects such as store merchandise, postal packages and sometimes living organisms (like pets). RFID uses low-powered radio transmitters to read data stored in a transponder (tag) at distances ranging from one inch to 100 feet. RFID tags are used to track assets, manage inventory and authorize payments, and they increasingly serve as electronic keys for everything from autos to secure facilities. RFID works using small (sometimes smaller than a fingernail) pieces of hardware called RFID chips. These chips feature an antenna to transmit and receive radio signals. So-called passive RFID chips do not have a power source, but active RFID chips do. RFID chips may be attached to objects, or in the case of some passive RFID systems, injected into objects.
Rician channel
Rician channel is a transmission channel that may have a line-of-sight component and several scattered of multipath components. This fading characteristic exhibits a Rician PDF (Probability Density Function).

Rician fading
Rician fading is a type of signal fading having a characteristic similar to the Rician PDF (Probability Density Function). It is used to model the mobile radio propagation.
Rician PDF
Rician PDF is a type of signal fading caused by independent multipath signals. The Rician PDF reduces to the Rayleigh PDF for the special case when s = 0.

RLC: Radio Link Control
Radio Link Control (RLC) is a link-layer protocol that is responsible for error recovery and flow control in 3G (UMTS) cellular systems. Compared with its counterpart developed for CDMA-2000 systems, i.e., Radio Link Protocol (RLP), RLC is a more advanced protocol and can support different QoS requirements desired by the users.
RLP: Radio Link Protocol
Radio Link Protocol (RLP) is a link layer protocol used for 2G (GSM and cdmaOne) and CDMA-2000 (3G) network-based error corrections to ensure robust data transmission. RLP terminates at the Mobile Station (MS) and the Interworking Function (IMF) generally located at the Mobile Switching Centre (MSC). Cellular networks such as GSM and CDMA use different variations of RLP.

RNC: Radio Network Controller
The Radio Network Controller (RNC) is the governing element in the UMTS radio access network (UTRAN) responsible for control of the Node Base Stations (BS), that is to say, the base stations which are connected to the controller. The RNC carries out radio resource management, some of the mobility management functions and is the point where encryption is done before user data is sent to and from the mobile. The RNC connects to the Circuit Switched Core Network through Media Gateway (MGW) and to the SGSN (Serving GPRS Support Node) in the Packet Switched Core Network. There are three types of RNCs: C-RNC (Controlling RNC), D-RNC (Drift RNC) and S-RNC (Serving RNC).
Roaming refers to the movement of a mobile device from one wireless network location to another without interruption in service or loss in connectivity. When a call is made to a roaming mobile, the public telephone network will route the call to your service provider's network since that is where your phone number terminates. Your home network is then responsible for re-routing the call to the host network.

Rogue Access Point
Rogue Access Point is an unauthorized access point installed on a network that may provide an entry point for unauthorized network access.
RPC: Reverse Power Control
Reverse Power Control (RPC) is a method for a Wireless Local Loop (WLL), in which the number of times of power control value transmission is reduced to 1. RPC reduces unnecessary power consumption in the WLL system and improves the reliability of the communication system.

RPE-LTP: Regular Pulse Excited-Long Term Prediction
Regular Pulse Excited Long Term Prediction (RPELTP) is a type of speech coding using regularly spaced pulses in an excitation frame and a long-term predictor to model the fine structure (pitch).
RRS: Round Robin Scheduling
Round Robin Scheduling (RRS) is a scheduling scheme used in wireless network. Since many stations share one channel in a wireless network, this algorithm provides every station to transmit or receive on the shared channel at a regular interval. Round-robin is one of the simplest scheduling algorithms for processes in an operating system, which assigns time slices to each process in equal portions and in order, handling all processes without priority. Round-robin scheduling is both simple and easy to implement, and starvation-free. Round-robin scheduling can also be applied to other scheduling problems, such as network scheduling.

RRC: Radio Resource Control
Radio Resource Control (RRC) is a sublayer of Layer 3 on the UMTS 3G radio interface. RRC exists in the control plane only and provides information transfer service to the NAS (Non Access Stratum). RRC is responsible for controlling the configuration of UMTS radio interface Layers 1 and 2.
RRD: RF Receiving Device
RF Receiving Device (RRD) receives over the air data and forwards it to the mobile computer.

RRI: Reverse Rate Indicator
Reverse Rate Indicator (RRI) is a parameter in a 3G wireless network provided by the reverse link, which aids the Access Point in determining the rate at which the reverse link is sending data. The RRI is included as the preamble for reverse link frames, indicating the rate at which the data was sent.
RS: Relay Station
Relay Station (RS), a concept defined in the IEEE 802.16j for the WiMAX network, is a station with the following functions: (1) to relay user data and possibly control information between other stations, and (2) to execute processes that indirectly support mobile multihop relay. All RSs are managed by an MMR-BS, but they may have some control of relay functions within their neighborhood.

RSA: Rural Service Area
Rural Service Area (RSA) is a geographic area in the US over which a cellular operator is licensed to provide service. RSAs are a group of rural counties having common financial, commercial and economic ties and were used to license cellular services together in the latter 1980s. RSAs cross state lines in some instances and were developed during a public rule making process at the FCC in 1987 and 1988.
RSSI: Relative Signal Strength Indicator
Relative Signal Strength Indicator (RSSI) is a measurement of radia signals at the point in which they are received and measured.

RTG: Receive/transmit Transition Gap
Receive/transmit Transition Gap (RTG), a concept in the mobile wireless network, is a gap between the last sample of the uplink burst and the first sample of the subsequent downlink burst at the antenna port of the BS in a time division duplex (TDD) transceiver. This gap allows time for the base station (BS) to switch from receive to transmit mode. During this gap, the BS is not transmitting modulated data but simply allowing the BS transmitter carrier to ramp up, and the transmit/receive (Tx/Rx) antenna switch to actuate.
rtPS: Real-Time Polling Service
Real-Time Polling Service (rtPS) is one of the five QOS service types defined in the IEEE 802.16 WiMAX. The 802.16 protocol supports five types of QoS: UGS (Unsolicited grant service), rtPS (Real time polling Service), ertPS (Extended Real-time POLLING SERVICE), nrtPS (Non-real-time polling service and BE (Best effort service). The Real-Time Polling Service (rtPS) is designed to support real-time service flows that generate variable size data packets on a periodic basis, such as MPEG video. The service offers real-time, periodic, unicast request opportunities, which meet the flow's real-time needs and allow the SS to specify the size of the desired grant. This service requires more request overhead than UGS, but supports variable grant sizes for optimum data transport efficiency.

R-UIM: Removable User Identity Module
Removable User Identity Module (R-UIM), also known as UIM, is similar to a Subscriber Identity Module (SIM), but is designed for networks other than GSM such as CDMA. R-UIM cards support roaming between CDMA and GSM networks.

S/I: Signal-to-interference ratio
Signal-to-interference ratio (S/I) is the ratio of power in a signal to the interference power in the channel. The term is usually applied to lower frequency signals, such as voice waveforms, but can also be used to describe the carrier wave. See also carrier-to-interference ratio.
S/N: Signal-To-Noise Ratio
Signal-To-Noise Ratio (S/N) is a measure of the power of a signal versus noise. A higher ratio means that there is more signal relative to noise.

SABP: Service Area Broadcast Protocol
Service Area Broadcast Protocol (SABP) is a 3G UMTS protocol for information broadcasting services, which allows cellular operators to deliver information such as stock prices, traffic information, weather reports and emergency alerts to mobile users within selected cells of the network.
SACCH: Slow Associated Control Channel
Slow Associated Control Channel (SACCH) is a GSM signalling channel that provides a relatively slow signalling connection. The SACCH is associated with either a traffic or dedicated channel. The SACCH can also be used to transfer Short Message Service (SMS) messages if associated with a traffic channel.

SALT: Speech Application Language Tags
The Speech Application Language Tags (SALT) specification largely overlaps the VoiceXML specification and both are under review by the same W3C working group. Both specifications share some common functionality, but SALT includes multi-modal capabilities for inputting and outputting data, making speech and traditional data I/O more interchangeable.
Sampling is the process performed in the conversion of analog waveforms to a digital format. It converts a continuous time signal into a discrete time signal or sequence of numbers.

SAT: Set-up Audio Tone
Set-up Audio Tone (SAT) is an audio tone in the 6 kHz range added to the downlink or forward channel in analog cellular systems. The mobile detects and returns the tone. The SAT tone is used to determine channel continuity, and only one SAT tone is usually assigned to a base station or sector.
A satellite is a specialized wireless receiver/transmitter that is launched by a rocket and placed in orbit around the earth. They are used for such diverse purposes as weather forecasting, television broadcast, amateur radio communications, Internet communications, and the Global Positioning System.

Satellite Communication
Satellite Communication refers to the use of orbiting satellites to relay data between multiple earth-based stations. Satellite communications offer high bandwidth and a cost that is not related to distance between earth stations, long propagation delays, or broadcast capability.
Satellite Internet
Satellite Internet refers to utilize telecommunications satellites in Earth orbit to provide Internet access to consumers. Satellite Internet service covers areas where DSL and cable access is unavailable. Satellite offers less network bandwidth compared to DSL or cable, however. In addition, the long delays required to transmit data between the satellite and the ground stations tend to create high network latency, causing a sluggish performance experience in some cases. Network applications like VOIP, VPN and online gaming may not function properly over satellite Internet connections due to these latency issues.

Satellite phone
Satellite phone is a type of wireless mobile telecommunications system using satellites as base stations. Such systems have the ability of providing service to the oceans and other remote areas of the globe.
Scattering is a phenomenon that occurs when the medium through which a radio wave travels consists of objects with dimensions small compared to the wavelength and diffuses the wave as it propagates through it.

SCCH: Signaling Control Channel
Signaling Control Channel (SCCH) is a logical channel used in the PDC system to convey signalling information between the mobile and the network.
SCH: Synchronization Channel
Synchronization Channel (SCH) is a logical channel used by mobile stations to achieve time synchronization with the network. SCH is used in GSM, cdma2000, and W-CDMA systems.

SDCCH: Stand-alone Dedicated Control Channel
Stand-alone Dedicated Control Channel (SDCCH) is used in the GSM system to provide a reliable connection for signalling and Short Message Service (SMS) messages. The Slow Associated Control Channel(SACCH) is used to support this channel.
SDMA: Space Division Multiple Access
Space Division (or Diversity) Multiple Access (SDMA), also known as multiple beam frequency reuse, employs spot beam antennas to reuse frequencies by pointing the antenna beams using the same frequency in different directions.

SDP: Service Discovery Protocol
In the Bluetooth protocol stack, the Service Discovery Protocol (SDP), also known as Bluetooth SDP, provides special means for applications in the Bluetooth environment to discover which services are available and to determine the characteristics of those available services. The SDP defines how a Bluetooth client's application shell acts to discover available Bluetooth servers' services and their characteristics. The protocol defines how client can search for a service based on specific attributes without the client knowing anything of the available services. The SDP provides means for discovery of new services becoming available when the client enters an area where a Bluetooth server is operating. The SDP also provides functionality for detecting when a service is no longer available.
Sector is a coverage area associated with a base station having its own antennas, radio ports and control channels. The concept of sectors was developed to improve co-channel interference in cellular systems, and most wireless systems use three sector cells.

Sector Antenna
Sector Antenna is an antenna type that radiates in only a specific direction. Multiple sector antennas are commonly used in point-to-multipoint situations.
Service area
Service area is the specified area over which the operator of a wireless communications network or system provides services.

SF: Spreading Factor
The Spreading Factor (SF) is the ratio of the chips to baseband information rate. Spreading factors vary from 4 to 512 in FDD UMTS. Spreading factor in dBs indicates the process gain. The lower the spreading factor the higher the data rate.
SFHMA: Slow Frequency Hopped Multiple Access
Slow Frequency Hopped Multiple Access (SFHMA) is a spread-spectrum system where the hop (dwell) time is much greater the information symbol period. When hopping is coordinated with other elements in the network, the multiple access interference in the network is greatly reduced.

SFN: Single Frequency Network
A single-frequency network (SFN) is a broadcast network where several transmitters simultaneosly send the same signal over the same frequency channel. Analogue FM and AM radio broadcast networks as well as digital broadcast networks can operate in this manner. The aim of SFNs is efficient utilization of the radio spectrum, allowing a higher number of radio and TV programs in comparison to traditional multi-frequency network (MFN) transmission. An SFN may also increase the coverage area and decrease the outage probability in comparison to an MFN since the total received signal strength may increase to positions midway between the transmitters.
SGF: Signaling Gateway Function
Signaling Gateway Function (SGF), a component in the IP Multimedia Subsystem, provides signaling conversion (in both directions) between Signaling System 7 (SS7) and IP networks.

SGSN: Serving GPRS Support Node
The Serving GPRS Support Node (SGSN) is the node which, in some sense, carries out the same function as the Local Agent in Mobile IP. However, an SGSN is actually considerably more complex since it also does the full set of interworking with the connected radio network. This means that the functions carried out by the SGSN vary quite considerably between GSM and UMTS.
Shadow fading
Shadow fading is a phenomenon that occurs when a mobile moves behind an obstruction and experiences a significant reduction in signal power.

SHF: Super High Frequency
Super High Frequency (SHF) is the RF spectrum between 3 GHz and 30 GHz.
SiGe: Silicon-Germanium Technology
Silicon-Germanium Technology (SiGe) makes it possible to design complex chips that integrate the functions of a cellular telephone, an e-mailbox and an Internet browser into a handheld information device with rapid data-transfer capability.

Signal Booster
Signal Booster compensates for loss of effect (weakening of the signal in the coaxial cable) between the outer antenna and the phone. It can apply to both incoming and outgoing signals.
Signal Diversity
Signal Diversity is a process by which two small dipole antennas are used to send and receive, combining their results for better effect.

Signal loss
Signal loss is the amount of signal strength that's lost in antenna cable, connectors, and free space. Signal loss is measured in decibels.
Signal Strength
Signal Strength is the strength of the radio waves in a wireless network.

Silent Alert
Silent Alert is the non-audible signal in a beeper, which discretely notifies individuals of incoming pages, typically by vibration.
SIM Card
Subscriber Identity Module (SIM) Card is used in the GSM phones to carry all critical information about the phone and subsriber.

SIM: Subscriber Identity Module
Subscriber Identity Module (SIM) is a component of a Mobile System (MS) in a GSM network that contains all the subscriber information.
SIMO: Single Input Multiple Output
Single Input Multiple Output (SIMO) is a form of smart antenna technology for wireless communications in which a single antenna at the transmitter and multiple antennas are used at the destination (receiver). An early form of SIMO, known as diversity reception, has been used by military, commercial, amateur, and shortwave radio operators at frequencies below 30 MHz since the First World War. The other forms of smart antenna technology include Single Input Single Output(SISO), Multiple Input Multiple Output (MIMO) and Multiple Input Single Output (MISO).

Simulcast refers to broadcasting a message over multiple transmitters throughout a geographical region at precisely the same time.
SINR: Signal to Interference plus Noise Ratio
Signal to Interference plus Noise Ratio (SINR) is the ratio of the received strength of the desired signal to the received strength of undesired signals (noise and interference).

SISO: Single Input Single Output
Single Input Single Output (SISO) is a form of antenna technology for wireless communications in which a single antenna at both the transmitter and at the destination (receiver) are used.
Site survey
Site survey is a survey conducted at the location for a new WLAN in an effort to avoid what could be time-consuming and costly problems down the road. It involves diagramming the network, checking the building and testing the equipment.

SLF: Subscription Locator Function
Subscription Locator Function (SLF), a component in the IP Multimedia Subsystem (IMS), locates the database containing subscriber data in response to queries from the I-CSCF (Interrogating-Call Session Control Functions) or application server (AS).
Slotted ALOHA
Slotted ALOHA is an access technique synchronizing the transmitters to time-slots in the channel and having the transmitter wait until the next available slot to send its packet.

Slow fading
Slow fading is a long-term fading effect changing the mean value of the received signal. Slow fading is usually associated with moving away from the transmitter and experiencing the expected reduction in signal strength.
SM: Spatial Multiplexing
Spatial Multiplexing (SM) is a transmission technology developed by Stanford University and Iospan Wireless in California exploiting multiple antennas at both the BS and CPE to dramatically increase the bit rate in a wireless radio link with no additional power or bandwidth consumption. Under certain conditions, SM offers linear increase in spectrum efficiency with the number of antennas.

Smart phone
Smart phone is a wireless phone with text and Internet capabilities. Smart phones can handle wireless phone calls, hold addresses and take voice mail and can also access information on the Internet and send and receive e-mail and fax transmissions.
SMATV: Satellite Master Antenna Television
Satellite Master Antenna Television (SMATV) refers to the transmission of television programming to a Satellite Master Antenna installed on top of an apartment building, a hotel, or at another central location from where it serves a private group of viewers. The transmission usually is done in C-band to 1.5 or 2 meter dishes.

SMG: Special Mobile Group
Special Mobile Group (SMG) is a standards body within ETSI that develops specifications related to mobile networking technologies, such as GSM and GPRS.
SMLC: Serving Mobile Location Center
Serving Mobile Location Center (SMLC), either a separate network element or integrated functionality in the Base Station Controller(BSC), contains the functionality required to support Location Services (LCS). The SMLC manages the overall coordination and scheduling of resources required for the location of a mobile unit. The SMLC may control a number of Location Measurement Unit (LMU) for the purpose of obtaining radio interface measurements to locate or help locate Mobile Station (MS) subscribers in the area that it serves.

SMLCPP: Serving Mobile Location Center Peer-to-Peer Protocol
Serving Mobile Location Center Peer-to-Peer Protocol (SMLCPP) is a transport protocol for the communication between the Serving Mobile Location Centers (SMLCs). The main functions of SMLCPP are: (1) allowing an SMLC to ask for and obtain information about Radio Interface Timing (RIT), as known from measurements done by LMUs not under its direct control; (2) allowing an SMLC, that controls deciphering keys in the location area, to sent them to other SMLCs in the same location area.
SMPP: Short Message Peer to Peer
Short Message Peer to Peer (SMPP) is a protocol for exchange short messages between SMS peer entities such as short message service centers. SMPP is often used to allow third parties (e.g. value-added service providers like news organisations) to submit messages, often in bulk.

SMR: Specialized Mobile Radio
Specialized Mobile Radio (SMR) is a dispatch radio and interconnect service for businesses, covering frequencies in the 220 MHz, 800 MHz and 900 MHz bands.
SMS: Short Message Service
Short Message Service (SMS) refers to the service that allows the transmission of short text messages among mobile devices such as cell phones, fax machines and BlackBerry devices. SMS was originally designed as part of GSM, but is now available on a wide range of networks, including 3G networks. There are two forms of SMS: Short Message Service - Point-to-Point (SMS-PP) and Short Message Service - Cell Broadcast (SMS-CB). The message length is 140 bytes. Larger contents (known as long SMS or concatenated SMS) can be sent segmentedly over multiple messages, in which case each message will start with a user data header (UDH) containing segmentation information.

SMS-CB: Short Message Service - Cell Broadcast
Short Message Service - Cell Broadcast (SMS-CB), a form of Short Message Service for the delivering of short messages over the mobile networks, allows messages (advertising, public information, etc.) to be broadcast to all mobile users in a specified geographical area.
SMS-PP: Short Message Service - Point to Point
Short Message Service - Point to Point (SMS-PP), a form of Short Message Service for the delivering of short messages over the mobile networks, provides, allows messages to be sent from an individual to another.

SNIR: Signal to Noise + Interference Ratio
Signal-to-Noise + Interference Ratio (SNIR) is the ratio of usable signal being transmitted to the undesired signal (noise) plus interference from other or the same channels. It is a measure of transmission quality. The ratio of good data (signal) to bad (noise + intereference) on a line is expressed in decibels (dB).
SNR: Signal-to-noise Ratio
Signal-to-noise Ratio (SNR) is the ratio of usable signal being transmitted to the undesired signal (noise). It is a measure of transmission quality. The ratio of good data (signal) to bad (noise) on a line is expressed in decibels (dB).

S-OFDMA: Scalable Orthogonal Frequency Division Multiple Access
Scalable Orthogonal Frequency Division Multiple Access (SOFDMA or S-OFDMA) is a flavor of the Orthogonal Frequency Division Multiplexing (OFDM), which is a technique for transmitting large amounts of digital data over a radio wave.
SHO: Soft Handoff
Soft Handoff (SHO) refers to two base stations -- one in the cell site where the phone is located and the other in the cell site to which the conversation is being passed, but both are held on the call until the handoff is completed. The first cell site does not cut off the conversation until it receives information that the second is maintaining the call.

Software Access Point
Software Access Point is a wireless-enabled computer running special software that enables it to act exactly like an wireless access point.
Space diversity
Space diversity is a diversity technique widely used in wireless systems since the very beginning. It consists of two receiving antennas physically (spatially) separated to provide de-correlated receiving signals.

SPACH: SMS Point-to-point CHannel
SMS Point-to-point Channel (SPACH) is a logical channel as a part of FDCCH (Forward Digital Control Channel) used to send signaling and control information from the cell site to the user receiver. SPACH can be further divided into three logical channels: ARCH, SMSCH and PCH.
Spectrum refers to a continuous range of frequency for electromagnetic waves.

Spectrum Allocation
Spectrum Allocation refers to that government designation of a range of frequencies for a category of use or uses. Allocation, typically accomplished in years-long FCC proceedings, tracks new technology development. However, the FCC can shift existing allocations to accommodate changes in spectrum demand. As an example, some UHF television channels were recently reallocated to public safety.
Spectrum Assignment
Spectrum Assignment refers to the government authorization for use of specific frequencies or frequency pairs within a given allocation, usually at stated geographic location(s). Mobile communications authorizations are typically granted to private users, such as oil companies, or to common carriers, such as cellular and paging operators.

Spectrum Reuse
Spectrum Reuse means re-applying the already assigned over-the-air spectrum to Cable TV programs. Historically, the over-the-air spectrum has been assigned to many purposes other than that of carrying TV signals. This has resulted in an inadequate supply of spectrum to serve the needs of viewers. Cable can reuse spectrum that is sealed in its aluminum tubes.
Spectrum spreading
Spectrum spreading is the process of increasing the occupied spectrum of a signal well beyond the needed to transmit the information.

Speech coding
Speech coding is an electronic process of sampling and digitizing a voice signal.
Spread spectrum
Spread spectrum is a form of wireless communications in which a signal's frequency is deliberately varied. This increases bandwidth and lessens the chances of interruption or interception of the transmitted signal.

SR: Spread Rate
Spread rate (SR), also known as the chip rate, is the rate of the digital code used to spread the information. The spreading rate is typically at least 100 times the information rate.
SRNC: Serving Radio Network Controller
Serving Radio Network Controller (SRNC or Serving RNC) is a type of Radio Network Controller (RNC) in a 3G mobile wireless network. The key functons of the Serving RNC: terminates the mobile link layer communications, terminates the IU, and exerts Admission Control over new mobiles or services attempting to use the Core Network over its IU interface. Admission Control ensures that mobiles are only allocated radio resources (bandwidth and signal/noise ratio) up to what the network has available.

SS: Subscriber Station
A Subscriber Station (SS) refers to a generalized equipment set providing connectivity between subscriber equipment and a Base Station in the mobile wireless network.
SSB: Single-sideband modulation
Single-sideband modulation (SSB) is a refinement of the technique of amplitude modulation designed to be more efficient in its use of electrical power and bandwidth. It is closely related to vestigial sideband modulation (VSB). To produce an SSB signal, a filter removes one of the sidebands. Most often, the carrier is reduced (suppressed) or removed entirely. Assuming both sidebands are symmetric, no information is lost in the process. What remains still contains the entire information content of the AM signal, using substantially less bandwidth and power, but cannot now be demodulated by a simple envelope detector.

SSD: Shared Secret Data
Shared Secret Data (SSD) is part of an encryption process supporting authentication of mobile phones. It uses an encryption key installed in the phone at the time of activation and known to the system through an entry in the HLR, that protects signalling and identity information. It can also be used to establish a voice privacy key.
SSI: Service Set Identifier
A Service Set Identifier (SSI) is a sequence of characters unique to a specific network or network segment that's used by the network and all attached devices to identify themselves and allow devices to connect to the correct network when more than one independent networks are operating in nearby areas.

SSID: Service Set Identifier
Service Set Identifier (SSID) is a set of 32 characters that give a unique name to a WLAN. All wireless devices on a WLAN must employ the same SSID in order to communicate with each other. The SSID on wireless clients can be set either manually, by entering the SSID into the client network settings, or automatically, by leaving the SSID unspecified or blank. A network administrator often uses a public SSID, that is set on the access point and broadcast to all wireless devices in range. Some newer wireless access points disable the automatic SSID broadcast feature in an attempt to improve network security.
STAP: Space-Time Adaptive Processing
Space-Time Adaptive Processing (STAP) is a signal processing technique that enhances the ability of radars to detect targets that might otherwise be obscured by clutter or by jamming. To implement STAP requires sampling the radar returns at each element of an antenna array, over a dwell encompassing several pulse repetition intervals. STAP is for applications such as Sensor Craft, Targets Under Trees, and space-based radar programs.

STBC: Space Time Block Coding
Space time block coding (STBC) is a technique used in wireless communications to transmit multiple copies of a data stream across a number of antennas and to exploit the various received versions of the data to improve the reliability of data-transfer. The fact that transmitted data must traverse a potentially difficult environment with scattering, reflection, refraction and so on and, as well as, be corrupted by thermal noise in the receiver means that some of the received copies of the data will be "better" than others. This redundancy results in a higher chance of being able to use one or more of the received copies of the data to correctly decode the received signal. In fact, STBC combines all the copies of the received signals in an optimal way to extract as much information from each of them as possible.
STC: Space Time Coding
Space Time Coding (STC) is a method employed to improve the reliability of data transmission in wireless communication systems using multiple transmit antennas. STCs rely on transmitting multiple, redundant copies of a data stream to the receiver in the hope that at least some of them may survive the physical path between transmission and reception in a good enough state to allow reliable decoding.

STD: Selective Transmit Diversity
Selective Transmit Diversity (STD) is a transmit diversity technique using multiple base stations to originate the signal and provide spatial diversity on the downlink. In STD, the transmitter selection is based on a QoS measurement made at the mobile station. See also transmit diversity, TDTD and TSTD.
STTC: Space --Time Trellis Coding
Space --Time Trellis Coding (STTC) is a type of space --time coding (STC) used in multiple-antenna wireless communications. This scheme transmits multiple, redundant copies of a trellis (or convolutional) code distributed over time and a number of antennas ("space"). These multiple, "diverse" copies of the data are used by the receiver to attempt to reconstruct the actual transmitted data. For a STC to be used, there must necessarily be multiple transmit antennas, but only a single receive antennas is required; nevertheless multiple receive antennas are often used since the performance of the system is improved by so doing.

Sub Network
Sub Network is a way of denoting a group of network layers that appear as one to a higher protocol layer.
Supplementary services
Supplementary services is a group of network layer protocol functions that provide call independent functions for mobile phones. These include: call forwarding, follow-me, advice of charge, reverse charging, etc.

Symbian is a software licensing company that develops and supplies the advanced, open, standard operating system -- Symbian OS -- for data-enabled mobile phones.
Based on XML, SyncML enables data synchronization between mobile devices and networked services. SyncML is transport, data type and platform independent. SyncML works on a wide variety of transport protocols, including HTTP and WSP (part of WAP), and with data formats ranging from personal data (such as vCard and vCalendar) to relational data and XML documents. The SyncML consortium was set up by IBM, Nokia and Psion and is sponsored by Symbian.

TACS: Total Access Communication System
Total Access Communication System (TACS) is the European version of AMPS -- the 1G technology for mobile wireless. ETACS was an extended version of TACS with more channels. TACS and ETACS are now obsolete in Europe, having been replaced by the more scalable and all-digital GSM system.
TAMS: Track and Manage Service
Track and Manage Service (TAMS) offers scheduled reporting on the status reports of industry standard sensors, GPS position and other event status reports.

TAP: Telocator Alphanumeric Protocol
Telocator Alphanumeric Protocol (TAP) is a simple protocol dedicated to the forwarding of alphanumeric pages. Although the features and capabilities of TAP are in TDP, the TAP protocol may co-exist with TDP. The TAP protocol may be utilized to forward binary data to RF-linked computers if input is formatted and processed.
TCH/F: Traffic Channel - full rate
Traffic Channel - full rate (TCH/F) is a traffic channel using full rate voice coding.

TCH/H: Traffic Channel - half rate
Traffic Channel - half rate (TCH/H) is a traffic channel using half rate voice coding.
TCH: Traffic Channel
Traffic Channel (TCH) is a logical channel that allows the transmission of speech or data. In most second generation systems, the traffic channel can be either full or half rate.

TCM: Trellis Code Modulation
Trellis Coded Modulation (TCM) is one of the coded modulation techniques used in digital communications. It combines the choice of a modulation scheme with that of a convolutional code together for the purpose of gaining noise immunity over encoded transmission without expanding the signal bandwidth or increasing the transmitted power.
TCP: Telocator Conversion Processor
Telocator Conversion Processor (TCP) is a front end processor which executes the Telocator Format Conversion (TFC) process.

TCS: Telephony Control Protocol Specification
The Telephony Control Protocol Specification (TCS) is a protocol in the Bluetooth protocol stack that defines ways to send audio calls between Bluetooth devices. It also controls the device mobility management procedures. It can be used to create a three-in-one phone:
On the move, a mobile phone connected to a cellular network;
At home, a cordless phone connected to a PSTN via a gateway or base station;
At the office, an intercom.
TD-CDMA: Time Division, Code Division Multiple Access
Time Division, Code Division Multiple Access (TD-CDMA) is a 3G proposal combining elements of TDMA and CDMA. It is developed and used primarily in China, combining time division multiplexing with CDMA techniques.
TDD: Time Division Duplex
Time Division Duplexing (TDD) refers to a transmission scheme that allows an asymmetric flow for uplink and downlink transmission which is more suited to data transmission. In a Time Division Duplex system, a common carrier is shared between the uplink and downlink, the resource being switched in time. Users are allocated one or more timeslots for uplink and downlink transmission.

TDMA: Time Division Multiple Access
Time Division Multiple Access (TDMA) divides a radio frequency available to a network into time slots and then allocates slots to multiple calls. So one frequency can support multiple, simultaneous data channels, using bandwidth more efficiently than earlier technologies. Available in 800-MHz or 1900-MHz frequencies, TDMA is used by the GSM digital cellular system.
TDN: Temporary Directory Number
Temporary Directory Number (TDN) is a temporary identification number assigned to a mobile while attached to the network.

TDP: Telocator Data Protocol
Telocator Data Protocol (TDP) is a suite of protocols used for sending messages from a computer, through a paging system, to a mobile receiving computer. Together, these protocols define the flow of messages from input devices through several processing steps until the entire message is received by an RF-linked computer. The set is compromised of several protocols, including TME, TRT, and TMC.
TD-SCDMA: Time Division Synchronous Code Division Multiple Access
Time Division Synchronous Code Division Multiple Access (TD-SCDMA) is a new technology developed by Siemens and the China Academy of Telecommunication Technology (CATR). TD-SCDMA is part of the ITU 3G standard harmonization and will likely be adopted by some operators in China. This proposed standard is 1.6 MHz wide and uses multiple timeslots, synchronous CDMA, and new detection and interference cancellation schemes.

TDTD: Time Division Transmit Diversity
Time Division Transmit Diversity (TDTD) is a technique utilizing multiple transmit stations to originate the downlink signal and improve performance. The transmit station used can be determined by either a fixed pattern or based on a QoS measurement made at the mobile. See also STD and TSTD.
Telematics means the integration of wireless communications, vehicle monitoring systems and location devices.

TFC: Telocator Format Conversion
Telocator Format Conversion (TFC) describes how binary data messages may be forwarded to RF-linked computers through the use of TAP protocol.
TID: Tunnel Identifier
Tunnel Identifier (TID), containing an MM Context ID and an NSAPI, is used to identify a GTP tunnel between two GSNs in a GPRS network. A tunnel is created whenever an SGSN sends a Create PDP Context Request in a GPRS network.

TIA: Telecommunications Industry Association
Telecommunications Industry Association (TIA) is one of the Telecommunications standards setting bodies in the United States.
Time dispersion
Time dispersion is a manifestation of multipath propagation that stretches the signal in time so that the duration of the received signal is greater than the transmitted signal.

Time diversity
Time diversity is the technique used by CDMA systems to overcome the effects of multipath fading. Through the use of a rake receiver, individual elements or fingers can be offset in time to account for different arrival times of multipath signals.
TinyOS is an open source component-based operating system and platform targeting wireless sensor networks. TinyOS is an embedded operating system, written in NesC programming language, as a set of cooperating tasks and processes. It is designed to be able to incorporate rapid innovation as well as to operate within the severe memory constraints inherent in sensor networks. It is intended to be incorporated into smartdust.

TIPP: Telocator Interswitch Paging Protocol
Telocator Interswitch Paging Protocol (TIPP) is a TCP/IP-based inter-PMP protocol utilized to move information across a network of PMP's TKIP: Temporal Key Integrirty Protocol.
Temporal Key Integrity Protocol (TKIP) is part of the IEEE 802.11i encryption
standard for wireless LANs security. TKIP utilizes RC4 stream cippher with 128 bit key for encryption and 64 bit key for authentication. TKIP is the next generation of WEP (Wired Equivalency Protocol). TKIP provides per-packet key mixing, a message integrity check and a re-keying mechanism, thus fixing the flaws of WEP.

TMC: Telocator Mobile Computer Protocol
Telocator Mobile Computer Protocol (TMC) is the protocol that operates between the Radio Frequency (RF) receiver and the mobile computer, which is the ultimate recipient of data sent from the Message Entry Device (MED).
TME: Telocator Message Entry Protocol
Telocator Message Entry Protocol (TME) defines the protocol operating between the Message Entry Device (MED) and Paging Message Processor (PMP).

TMSI: Temporary Mobile Station Identity
Temporary Mobile Station Identity (TMSI) is an identification number assigned to a mobile station while it is attached to the network. This number is maintained in the VER and SIM while the mobile is attached to the network and is used to route calls to and from the mobile.
TMSI: Temporary Mobile Subscriber Identity
Temporary Mobile Subscriber Identity (TMSI) is the identity that is most commonly sent between the mobile and the network. It is a randomly allocated number that is given to the mobile at the moment it is switched on. The number is local to a location area, and so it has to be updated, each time the mobile moves to a new geographical area. The network can also change the TMSI of the mobile at any time. And it normally does so, in order to avoid the subscriber from being identified, and tracked by eavesdroppers on the radio interface.

TM-UWM: Time-Modulated Ultra-Wide Band
Time-Modulated Ultra-Wide Band (TM-UWM), developed by Time Domain, uses short, coded pulses transmitted over a wide range of frequencies, making it useful for a broad range of applications from networking to through-the-wall radar and secure communications.
TNPP: Telocator Network Paging Protocol
Telocator Network Paging Protocol (TNPP) is a protocol used for moving pages from one paging system to another over the standard lines.

TOA: Time OF Arrival
Time OF Arrival (TOA) is a location technique that uses GSM timing to triangulate the position of a handset relative to active base stations. Accuracy is good indoors and in areas of dense base-station coverage, and TOA can be used with legacy handsets. Specialized equipment is needed at the base station, however, and planning, deployment, and maintenance costs can be high.
Transcoding refers to the operation of changing data from one format to another, such as an XML to HTML, so the output will be displayed in an appropriate manner for the device.

Transmission Frequency
Transmission Frequency is the rate in hertz at which a radio transmitter repeats a signal pattern. It is also a code number that the wireless service company assigns to represent a single frequency or set of frequencies.
Transmit Power
Transmit Power is the amount of power used by a radio transceiver to send the signal out. Transmit power is generally measured in milliwatts, which you can convert to dBm.

Transmitter is a device that generates radio waves and sends them to the antenna.
TrGW: Translation Gateway
Translation Gateway (TrGW) is a component used in the IP Multimedia Subsystem (IMS) network, which provides translation of IPv4/IPv6 address and port numbers, as well as translation of IPv4 and IPv6 protocols.

Tri-band refers to a wireless phone that works on three bands. CDMA and TDMA tri-band phones work on 1900MHz and 800MHz digital frequencies, and 800MHz analog cellular -- popular standards in the United States. Tri-band GSM phones are all digital, operating on 1900Mhz in the United States and 1800Mhz and 900Mhz in other countries.
Tri-mode: Triple mode (tri-mode)
Triple mode (Tri-mode) is a combined analog and digital mobile phone. Allows operation of the phone in the existing analog system at 800 MHz and in digital systems at both 800 MHz and 1900 MHz.

TRT: Telocator Radio Transport protocol
Telocator Radio Transport protocol (TRT) describes the format of data which is forwarded to RF receivers. This transport style protocol allows a receiver to collect several separate message inside different pages and then piece them together into one proper message. The manner in which this data is inserted into any particular radio pager encoding format is specific to the particular manufacturer's radio receiver.
TSTD: Time Switched Transmit Diversity
Time Switched Transmit Diversity (TSTD) is a technique utilizing multiple transmit stations to originate the downlink signal and improve performance. The transmit station used is determined by a fixed selection pattern similar to frequency hopping. See also STD and TDTD.

TTA: Telecommunications Technology Association
Telecommunications Technology Association (TTA) is a telecommunications standards setting body in Korea.
TTC: Telecommunications Technology Committee
Telecommunications Technology Committee (TTC) is a private-sector corporate body established in 1985 to prepare domestic standards relevant to Japanese telecommunications.

TTG: Transmit/receive Transition Gap
Transmit/receive Transition Gap (TTG), a concept in the mobile wireless networking, is a gap between the last sample of the downlink burst and the first sample of the subsequent uplink burst in a time division duplex (TDD) transceiver. This gap allows time for the base station (BS) to switch from transmit to receive mode. During this gap, the BS is not transmitting modulated data but simply allowing the BS transmitter carrier to ramp down, the transmit/receive (Tx/Rx) antenna switch to actuate, and the BS receiver section to activate.
TTI: Transmission Time Interval
Transmission Time Interval (TTI) is a parameter in UMTS (and other digital telecomunication networks) related to encapsulation of data from higher layers into frames for transmission on the radio link layer. TTI refers to the length of an independently decodable transmission on the radio link. The TTI is related to the size of the data blocks passed from the higher network layers to the radio link layer.

Turbo Code
Turbo code is a class of high-performance error correction codes finding use in deep-space satellite communications and other wireless communication applications where designers seek to achieve maximal information transfer over a limited-bandwidth communication link in the presence of data-corrupting noise. There are two types of turbo codes, Block Turbo Codes (BTCs) and Convolutional Turbo Codes (CTCs), which are quite different since they use different component codes, different concatenation schemes and different SISO algorithms.
TWO - WAY Communication
Two - Way Communication occur between communications of radio stations, each having a transmitter and receiver. The stations may be in fixed locations, mobile or portable ones, or in any combination.

UCD: Uplink Channel Descriptor
Uplink Channel Descriptor (UCD) is a concept in the IEEE 802.16 (WiMAX) network, which describes the uplink burst profile (i.e., modulation and coding combination) and preamble length for each UL burst.
UDLP: UniDirectional Link Protocol
UniDirectional Link Protocol (UDLP) is used by inexpensive, receive-only antennas to receive data via satellite.

UE: User Equipment
User Equipment (UE) refers to eqiment in a wireless network that enables users to communicate through wireless communication networks.
UGS: Unsolicited Grant Service
Unsolicited Grant Service (UGS) is one of the five QoS service types defined in the IEEE 802.16 WiMAX. The 802.16 protocol supports five types of QoS -- UGS (Unsolicited grant service), rtPS (Real time polling Service), ertPS (Extended Real-time POLLING SERVICE), nrtPS (Non-real-time polling service and BE (Best effort service). The Unsolicited Grant Service (UGS) is designed to support real-time service flows that generate fixed-size data packets on a periodic basis, such as T1/E1 and Voice over IP without silence suppression. The service offers fixed-size grants on a real-time periodic basis, which eliminate the overhead and latency of SS requests and assure that grants are available to meet the flow's real-time needs.

UHF: Ultra High Frenquency
Ultra High Frenquency (UHF) refers to the RF spectrum between 300 MHz and 3 GHz.
UICC: USIM Integrated Circuit Card
USIM Integrated Circuit Card (UICC) is the chip card used in mobile terminals in 3G telecom network systems. The UICC is an essential component for UMTS, just as the SIM for GSM. Extending the concept of the SIM card, the UICC contains the USIM application and also provides a platform for other IC Card applications. It ensures the integrity and security of all kinds of personal data, enabling secure support for all kinds of multi-application schemes.

UIM: User Identity Module
User Identity Module (UIM), also known as R-UIM, is the SIM card equivalent planned for W-CDMA handsets. UIM supports roaming between CDMA and GSM networks.
Ultra Wideband
Ultra Wideband is a wireless networking approach that broadcasts millions of tiny pulses at trillionth-of-second intervals using very low power over enormous swaths of spectrum. In comparison, traditional radios broadcast continuously on tiny bits of spectrum. Ultra Wideband is commonly abbreviated to UWB.

UMSC: UMTS Mobile Switching Center
UMTS Mobile Switching Center (UMSC), a type of Mobile Switching Center (MSC), is the place that provides UMTS 3G wireless telephony switching services and controls calls between telephone and data systems.
UMTS: Universal Mobile Telecommunications System
Universal Mobile Telecommunications System (UMTS) is a 3G cellular network technology that uses WCDMA (Wideband Code Division Multiple Access) technologies. The transmission rates range from a theoretical 384K bit/sec for mobile phones to 2M bit/sec for stationary devices.

UL: Uplink
Uplink (UL) is the transmission path from the mobile station up to the base station.
UPT: Universal Personal Telecommunications
Universal Personal Telecommunications (UPT) is a set of standards developed by the CCITT for wireline personal communications.

Urban cells
Urban cells is the coverage provided by base stations located in urban areas. The radius of these cells is usually much smaller than suburban and rural cells due to the more difficult propagation environment.
USDC: United States Digital Cellular
United States Digital Cellular (USDC), also known as IS-54 (Interim Standard 54), was developed to replace the AMPS standard, particularly in urban areas where AMPS did not provide adequate channel capacity. USDC allows the co-existence of AMPS so that providers can gradually phase out AMPS as needed. USDC utilizes TDMA to offer phone and paging service over a 25 kHz channel divided into two time slots.

USIM: Universal Subscriber Identity Module
Universal Subscriber Identity Module (USIM), also known as Upgrade SIM, is a component in the UMTS 3G network that securely stores the key identifying a mobile phone service subscriber, as well as subscription information, saved telephone numbers, preferences, text messages and other information. It is equivalent to the Subscriber Identity Module (SIM) in the GSM 2G wireless network.
USIM: Upgrade SIM
Upgrade SIM (USIM), also known as Universal Subscriber Identity Module, is an enhanced version of the SIM card, which is for use with IMT-2000/UMTS 3G network.

UTRA: UMTS Terrestrial Radio Access
UMTS Terrestrial Radio Access (UTRA) is a term used for UMTS radio access solution, applied to W-CDMA and TD-CDMA.
UTRAN LTE: UMTS Terrestrial Radio Access Network Long Term Evolution
UMTS Terrestrial Radio Access Network Long Term Evolution (UTRAN LTE), sometimes also referred to as 3G LTE or Super-3G, is the 3GPP radio technology evolution architecture.

UTRAN: UMTS Terrestrial Radio Access Network
UMTS Terrestrial Radio Access Network (UTRAN) is the radio access network based on the UTRA standard term describing the Radio Network Controllers and Node Base stations of a UMTS network. The UMTS network, built around an IP-optimized core network carrying all traffic types. UTRAN will support both UTRA Frequency Division Duplex (FDD) and Time Division Duplex (TDD) radio interfaces allowing flexible, high-bandwidth support, and will be connected to an IP-optimized core network through a UTRAN Gateway.
UUT: Unit Under Test
Unit Under Test (UUT) refers to some type of electrical apparatus connected to test instrumentation. The apparatus can range from a simple circuit to a complex subsystem such as a mobile phone, base station or MSC.

UWB: Ultra-Wide-Band
Ultra-Wide-Band (UWB), also called digital pulse, is a wireless technology defined in IEEE 802.15.3 for transmitting digital data over a wide swath of the radio frequency spectrum with very low power. Because of the low power requirement, it can carry signals through doors and other obstacles that tend to reflect signals at more limited bandwidths and a higher power. It can carry large amounts of data (maximum bandwidth of 1Gbps) and can be used for multimedia content transfer, high-resolution radar, ground-penetrating radar, and radio locations systems.
UWC: Universal Wireless Consortium
Universal Wireless Consortium (UWC) is an organization of vendors and operators promoting and implementing the IS-136 digital standard. Also specifying the future development of the standard and facilitating roaming agreements between IS-136 operators.

Universal Wireless Communications 136 (UWC-136) is proposed by the TIA and adopted by the ITU for 3G TDMA standard. It allows the US TDMA community to migrate from 1st (IS-136) to 3rd (UWC-136) generation systems. The standard uses a wideband TDMA technique.
UWCC: Universal Wireless Communications Consortium
Universal Wireless Communications Consortium (UMCC) is an industry group supporting IS-136 time division multiple access and IS-41 wireless intelligent network technology.

VAD: Voice Activity Detector
Voice Activity Detector (VAD) is the device that detects voice activity and allows DTX to operate. VAD, in conjunction with DTX reduces power consumption in the mobile station and RF interference in the system by muting the transmitter when there is no voice to transmit.
V-Band, also known as Q-Band, is a radio bandwidth range between 40 GHz t0 50 GHz.

vCARD is a standard defining the format of an electronic business card. All devices supporting vCard can exchange information such as phone numbers and addresses. For instance, a user with a vCard-aware phonebook application on a handheld computer can easily transfer names and phone numbers to a vCard-aware mobile phone.
VHF: Very High Frequency
Very High Frequency (VHF) is the RF spectrum between 30 MHz and 300 MHz.

Viterbi algorithm
Viterbi algorithm is a technique for searching a decoding trellis to yield a path with the smallest distance. This is also known as maximum likelihood decoding.
VLR: Visitor Location Register
Visitor Location Register (VLR) contains all subscriber data required for call handling and mobility management for mobile subscribers currently located in the area controlled by the VLR. The VLR communicates with the HLR of the subscriber to request data about that subscriber.

VMAC: Virtual Media Access Control
Virtual Media Access Control (Virtual MAC or VMAC) is an algorithm that passively monitors the radio channel and estimates locally achievable service levels. The VMAC estimates key MAC level statistics related to service quality such as delay, delay variation, packet collision, and packet loss.
Vocoder refers to a voice encoder which is a device that codes and decodes the human voice (sound waves) into digital transmission. Higher vocoder speeds offer enhanced sound quality.

Voice Activated Dialing
Voice Activated Dialing is a feature that permits you to dial a phone number by speaking it to your wireless phone instead of punching it in yourself. The feature contributes to convenience as well as driving safety.
Voice Channel
Voice Channel is a channel used for transmission of voice data from a base station to a cellular phone (forward voice channel) or from a cellular phone to a base station (reverse voice channel).

VoWIP: Voice over Wireless IP
Voice over Wireless IP (VoWIP) is the combination of VoIP with 802.11 wireless LANs to create a wireless telephone system. VoWIP enables businesses to leverage their wireless LANs to add voice communications, enabling companies to deploy and manage voice and data over a single wireless backbone. VoWIP applications require some reservation of bandwidth to support the real-time nature of voice. Proprietary standards like Spectralink Voice Priority (SVP) are today's solution; however, the IEEE is developing the 802.11e standard for quality of service as a long-term solution.
VoxML: Voice Markup Language
Voice Markup Language (VoxML) is a technology from Motorola for creating a voice dialog with a Web site in which a user can call a Web site by phone and interact with it through speech recognition and Web site responses.

VSB: Vestigial Sideband
Vestigial sideband (VSB) is a type of amplitude modulation technique that encodes data by varying the amplitude of a single carrier frequency. Portions of one of the redundant sidebands are removed to form a vestigial sideband signal. Television broadcasts (regardless of NTSC, PAL, or SECAM analog video format) use this method if the video is transmitted in AM, due to the enormous bandwidth used. It may also be used in digital transmission, such as the ATSC-standardized 8-VSB. The Milgo 4400/48 modem used vesitigial sideband and phase-shift keying to provide 4800 bit/s transmission over a 1600 Hz channel.
VSELP: Vector Sum Excited Linear Predictive
Vector Sum Excited Linear Predictive (VSELP) is a type of speech coding using an excitation signal generated from three components: the output of a long-term, pitch filter and two codebooks. VSELP was used in the IS-54 standard and operated at a rate of 8 kbps.

WAE: Wireless Application Environment
The Wireless Application Environment (WAE) is the top most level in the Wireless Application Protocol (WAP) suite, which combines both the WWW and Mobile Telephony technologies. WAE provides the operators and service providers an interoperable environment on which they can build applications and services for handheld client devices. WAE includes the micro-browser that contains functionality for using not only WML and WML Script as previously stated, but also Wireless Telephony Application, namely WTA and WTAI -- telephony services and programming interfaces as well as content formats including well-defined data formats, images, phone book records and calendar information.
Walsh Code
Walsh Code is a group of spreading codes having good autocorrelation properties and poor crosscorrelation properties. Walsh codes are the backbone of CDMA systems and are used to develop the individual channels in CDMA. For IS-95, here are 64 codes available. Code 0 is used as the pilot and code 32 is used for synchronization. Codes 1 though 7 are used for control channels, and the remaining codes are available for traffic channels. Codes 2 through 7 are also available for traffic channels if they are not needed. For cdma2000, there exists a multitude of Walsh codes that vary in length to accommodate the different data rates and Spreading Factors of the different Radio Configurations.

WAP Forum
The WAP Forum has consolidated into the Open Mobile Alliance (OMA) and no longer exists as an independent organization.
WAP: Wireless Access Point
A wireless access point (WAP), also known as Access Point (AP), is a device that "connects" wireless communication devices together to create a wireless network. WAPs act as a central transmitter and receiver of WLAN radio signals. Access points used in home or small business networks are generally small, dedicated hardware devices featuring a built-in network adapter, antenna, and radio transmitter. Access points support Wi-Fi wireless communication standards. Many WAPs can be connected together to create a larger network that allows "roaming".

WAP: Wireless Application Protocol
The Wireless Application Protocol (WAP) is a set of specifications, developed by the WAP Forum, that lets developers using Wireless Markup Language build networked applications designed for handheld wireless devices. WAP was designed to work within the constraints of these devices: a limited memory and CPU size, small, monochrome screens, low bandwidth and erratic connections. WAP browsers are intended to be implemented on small mobile devices such as cell phones, pagers, and PDAs. Instead of developing content in HTML and JavaScript, WAP developers use WML and WMLScript.
War chalking
War chalking refers to marking buildings or sidewalks with chalk to show others where it's possible to access an exposed company wireless network. These access points are typically found through war driving.

War driving
War driving (wardriving) is the process of traveling around looking for wireless access point signals that can be used to get network access. Some computer hackers are content to simply map any open, unsecured WLANs they find. Others have adopted the practice of warchalking, tagging nearby pavement to allow others to tap in and steal bandwidth from those hotspots.
WASP: wireless application service provider
Wireless Application Service Provider (WASP) provides hosted wireless applications so that companies will not have to build their own sophisticated wireless infrastructures.

W-ATM: Wireless Asynchronous Transfer Mode network
Wireless ATM network (W-ATM) was a concept of using wireless as physical layer to transmit ATM cells. This concept never took off.
Wavelength is the length of one complete wave of an alternating or vibrating phenomenon, generally measured from crest to crest or from trough to trough of successive waves.

WBMP: Wireless Bitmap
Wireless Bitmap (WBMP) is WAP graphic format optimized for mobile computing devices. A WBMP image is identified using a TypeField value, which describes encoding information (such as pixel and palette organization, compression, and animation) and determines image characteristics according to WAP documentation.
WAP Binary XML (WBXML), a compact representation of XML, is part of the presentation logic in Wireless Application Protocol (WAP). WBXML significantly improves the efficiency of transmitting XML over narrow bandwidth networks, where data size is of paramount importance.

WCA: Wireless Communications Association
The Wireless Communications Association (WCA) represents the fixed broadband wireless access industry worldwide. Its mission is to advance the interests of the wireless systems that provide data (including Internet and e-commerce), voice and video services on a subscription basis through land-based towers to fixed reception/transmit devices.
WCDMA: Wideband-Code Division Multiple Access
Wideband Wideband-Code Division Multiple Access(W-CDMA or WCDMA), also known as UMTS in Europe, is a 3G standard for GSM in Europe, Japan and the United States. It's also the principal alternative being discussed in Asia. It supports very high-speed multimedia services such as full-motion video, Internet access and video conferencing. It uses one 5-MHz channel for both voice and data, offering data speeds of up to 2 Mbps.

WDF: Wireless Data Forum
Wireless Data Forum (WDF) is an industry group based in New Zealand dedicated to promote and educate New Zealand companies on many options and solutions available to them through the use of Wireless Data.
WDP: Wireless Datagram Protocol
The Wireless Datagram Protocol (WDP), a protocol in WAP architecture, covers the Transmission Layer Protocols in an Internet model. As a general transport service, WDP offers to the upper layers an invisible interface independent of the underlying network technology used. In consequence of the interface common to transport protocols, the upper layer protocols of the WAP architecture can operate independent of the underlying wireless network. By letting only the transport layer deal with physical network-dependent issues, global interoperability can be acquired using mediating gateways.

WDS: Wireless Distribution System
Wireless Distribution System (WDS) is a technology that enables access points to communicate with one another in order to extend the range of a wireless network. WDS is appearing in 802.11g-based access points.
WECA: Wireless Ethernet Compatibility Alliance
Wireless Ethernet Compatibility Alliance (WECA) is the former name of the Wi-Fi Alliance of vendors promoting 802.11 wireless networking standards and compatibility.

WEP: Wired-Equivalent Privacy
Wired Equivalent Privacy (WEP) is a security protocol, specified in the IEEE Wireless Fidelity (Wi-Fi) standard, 802.11b, that is designed to provide a wireless local area network (WLAN) with a level of security and privacy comparable to what is usually expected of a wired LAN. WEP is based on a security scheme called RC4 that utilizes a combination of secret user keys and system-generated values. The original implementations of WEP supported the so-called 40-bit encryption, having a key of length 40 bits and 24 additional bits of system-generated data (64 bits total). Research has shown that 40-bit WEP encryption is too easy to decode, and consequently product vendors today employ 128-bit encryption (having a key length of 104 bits, not 128 bits) or better.
WiBro, standing for Wireless Broadband, is a wireless broadband internet technology being developed by the Korean telecoms industry. In February, 2002, the Korean government allocated 100 MHz of electromagnetic spectrum in the 2.3 GHz band, and in late 2004, WiBro Phase 1 was standardized by the TTA (Telecommunications Technology Association) of Korea.

WiDEN: Wideband Integrated Dispatch Enhanced Network
Wideband Integrated Dispatch Enhanced Network (WiDEN) is a software upgrade developed by Motorola for its iDEN-enhanced specialised mobile radio (or ESMR) wireless telephony protocol. WiDEN allows compatible subscriber units to communicate across four 25 kHz channels combined, for up to 100 kbit/s of bandwidth. The protocol is generally considered as a 2.5G wireless cellular technology.
Wi-Fi Alliance
Wi-Fi Alliance is a non-profit international association formed in 1999 to certify interoperability of WLAN products based on the IEEE 802.11 specification. Currently, the Wi-Fi Alliance has over 200 member companies from around the world, and over 1,000 products have received Wi-Fi certification since the certification began in March of 2000. The goal of the Wi-Fi Alliance's members is to enhance the user experience through product interoperability.

Wi-Fi: Wireless Fidelity
Wireless Fidelity (WiFi or Wi-Fi), originally Nick named for 802.11b for wireless LAN with bandwith up to 11 Mbps, now refers to the entire wireless LAN technologies including 802.11a, 802.11b, 802.11g and 802.11n etc. Wi-Fi is actually the industry name for wireless LAN (WLAN) communication technology related to the IEEE 802.11 family of wireless networking standards.
WIM: WAP Identity Module
WAP Identity Module (WIM) is the security module implemented in the SIM card for WAP applications. WIM provides security services for WAP applications, and allows you to use digital signature. SIM cards with security module are provided by the SIM card issuer.

WiMax, abreviated from Worldwide Interoperability for Microwave Access, is a popular name of the 802.16 wireless metropolitan-area network standard, including both 802.16-2004 for fixed WiMAX and 802.16-2005 for mobile WiMAX. WiMax has a range of up to 31 miles. Data rates for WiMax can reach up to 75 Mbps (Fixed) or 15 Mbps (Mobile). A number of wireless signaling options exist ranging anywhere from the 2 GHz range up to 66 GHz. WiMax is primarily aimed at making broadband network access widely available without the expense of stringing wires (as in cable-access broadband) or the distance limitations of Digital Subscriber Line. WiMax technology can deliver high-speed Internet access to rural areas and other locations. WiMax also offers an alternative to satellite Internet services.
WiMedia Alliance
WiMedia Alliance is an industrial association with a focus on UWB (Ultra WideBand) wireless technologies to promote and enable the rapid adoption and standardization of UWB worldwide for high-speed wireless, multimedia-capable personal-area connectivity in the PC, CE and mobile market segments; to provide a neutral and open forum for multiple industry segments to establish requirements, specifications and best practices for usability and interoperability; to promote worldwide UWB spectrum regulations; and to develop, maintain, enhance and reference technical specifications.

WIN: Wireless Intelligent Network
Wireless Intelligent Network (WIN) refers to a set of advanced services provided on a wireless network such as Prepaid, LNP, etc.
Wireless Bridge
Wireless Bridge is a networking bridge used to connect two or more separate networks. A wireless bridge functions in the same way but can be used in situations in which running a wire or cable would be impractical or prohibitively expensive, such as creating a 10-mile point-to-point link.

Wireless FireWire
Wireless FireWire, also known as wireless 1394, is a wireless version of the high speed FireWire communications protocol defined in the IEEE 1394. It allows multiple FireWire devices to communicate wirelessly over IEEE 802.15.3 (UWB) Wireless Personal Area Networks (WPANs). The wireless 1394 specification adapts the IEEE 1394 and P1394.1 bridging standards to the high bandwidth wireless network connectivity enabled by IEEE 802.15.3.
Wireless Channel
Wireless Channel refers to dividing allocated spectrum into sub-spectrums. For example, 802.11b and 802.11g devices have three nonoverlapping channels. 802.11a devices have eight nonoverlapping channels.

Wireless Gateway
Wireless Gateway is a device that can share an Internet connection, serve DHCP, and bridge between wired and wireless networks. Wireless Gateway may also be called as "wireless router," or "base station." Wireless Network Adaptor Wireless Network Adaptor is the inerface that connects a PC with wireless network, for example, a wireless NIC is a wireles adaptor.
Wireless router
Wireless routers are actually routers with Ethernet plus wireless access points so that they have both wired and/or wireless at the same time. Another combination is to build a DSL or cable modem with the wireless access point, in which the wireless access point is used to communicate with local PCs and other devices and the DSL and cable modem will communicate with the Inernet.

WISP: Wireless ISP
Wireless ISP (WISP) is a company that provides wireless Internet access for public. WISPs typically install Wi-Fi wireless hotspots in airports, hotels and other public businessplaces. These hotspots provide Internet access and local area network (LAN) printing for mobile network devices like laptops, handheld computers and cell phones.
WLAN: Wireless local-area networks (Wireless LAN)
Wireless local-area networks (WLAN or wireless LAN) use radio waves to connect a user device to a LAN, which extends an existing wired local area network. WLAN provides Ethernet connections over the air and operate under the 802.11 family of specifications developed by the IEEE. WLANs are built by attaching a device called the access point (AP) to the edge of the wired network. Clients communicate with the AP using a wireless network adapter similar in function to a traditional Ethernet adapter. The WLAN technology is defined by the IEEE 802.11 family of specifications, namely, 802.11, 802.11a, 802.11b, 802.11g and 802.11n. All use the Ethernet protocol and CSMA/CA (carrier sense multiple access with collision avoidance instead of CSMA/CD) for path sharing.

WLL: Wireless Local Loop
Wireless Local Loop (WLL), also called radio in the loop (RITL) or fixed-radio access (FRA) or fixed-wireless access (FWA), is the use of wireless connections as the last mile for delivering plain old telephone service (POTS) to customers.
WMF: Wireless Message Format
Wireless Message Format (WMF) is a standard format for presenting data received through a paging system to mobile computers. The application at the MED uses this format to encode binary data and control information to be sent to a remote device. This information is received completely intact by the MCD.

WML: Wireless Markup Language
Wireless Markup Language (WML), based on HTML and XML, delivers Internet content to small wireless devices, such as browser-equipped cellular phones and handheld devices, which typically have very small displays, slow CPUs, limited memory capacity, low bandwidth and restricted user-input capabilities. WML demands less memory and processing power from browsers than HTML and JavaScript. WML also includes features that tailor it for the relatively small display sizes of today's wireless devices. WML and HTML differ in significant ways. Although WML strips some features from HTML and co-opts others, WML also incorporates some powerful programming constructs not found in HTML like variables, tasks, and events. WML implements a stricter tag syntax than HTML and includes a DTD for use with XML parsers.
WOS: Wireless Office Systems
Wireless Office Systems (WOS) is a technology that allows the user to transfer calls to a mobile telephone.

WPA: Wi-Fi Protected Access
Wi-Fi Protected Access (WPA) is a data encryption specification for 802.11 wireless networks that replaces the weaker WEP. Created by the WiFi Alliance before a 802.11i security standard was ratified by the IEEE, it improves on WEP by using dynamic keys, Extensible Authentication Protocol to secure network access, and an encryption method called Temporal Key Integrity Protocol (TKIP) to secure data transmissions. WPA provides roughly comparable security to VPN tunneling with WEP, with the benefit of easier administration and use.
WPA2: Wi-Fi Protected Access 2
Wi-Fi Protected Access 2 (WPA2) is an enhanced version of WPA. It is the official 802.11i standard that was ratified by the IEEE in June, 2004. It uses the Advanced Encryption Standard instead of TKIP (see above). AES supports 128-bit, 192-bit and 256-bit keys.

WPABX: Wireless Private Automatic Branch Exchange
Wireless Private Automatic Branch Exchange (WPABX) is a customer premise telephone switching system using wireless technology to link the individual user stations to the central switching unit. The WPABX is capable of interfacing to a telephone central office with trunk groups and routing calls based on a 3- or 4-digit telephone extension number.
WPAN: Wireless Personal-Area Network
Wireless Personal-Area Network (WPAN) is a personal area network using wireless connections. WPAN is used for communications among devices such as telephones, computer and its accessories, as well as personal digital assistants, within a short range. The reach of a PAN is typically within 10 meters. Technologies enabling WPAN include Bluetooth, ZigBee, Ultra-wideband(UWB), IrDA, HomeRF, etc.

WRAN: Wireless Regional Area Network
Wireless Regional Area Network (WRAN) technology targets at wireless broadband (remote) access for geographically dispersed, sparsely populated areas. The transmission range can be up to 100Km, Non Line of Sight (NLOS) due to use of TV broadcast bands as License Exempt (LE) spectrum. The WRAN technology is useful for remote access to grid computer sites and to independent telcos operating in developing countries, rural or non- metropolitan areas. WRAN specifications are defined by the IEEE802.22 working committee.
WSP: Wireless Session Protocol
The Wireless Session Protocol (WSP), a protocol in the Wireless Application Protocol (WAP) suite, provides the Wireless Application Environment a consistent interface with two services: connection-oriented service to operate above the Transaction Layer Protocol (WTP) and a connectionless service that operates above either secure or non-secure datagarm service (WDP). Currently, the protocols of the WSP family provide HTTP/1.1 functionality and semantics in a compact encoding, long lived session state with session suspend-and-resume capabilities, a common facility for reliable and unreliable data push as well as a protocol feature negotiation. These protocols are optimised to be used in low-bandwith bearer networks with relative long latency in order to connect a WAP client to a HTTP server.

W-TDMA: Wideband Time Division Multiple Access
Wideband Time Division Multiple Access (W-TDMA) is a technique based on time division transmission which is similar to that used by GSM but provides a much higher transmission rate. It was submitted as a solution for UMTS radio interface, but was rejected.
WTLS: Wireless Transport Layer Security
The Wireless Transport Layer Security (WTLS) protocol, protocol in the Wireless Application Protocol (WAP) suite, is based on Transport Layer Security (TLS) or formely known as Secure Sockets Layer (SSL). It is designed to be used with other WAP protocols and to support narrow-band networks. It uses data encryption with a method that is negotiated at the start of the session to provide privacy, data integrity, authentication and denial-of-service protection. The latter is needed in cases when data is replayed or not properly verified. When that happens, WTLS detects the misuse and rejects the data in order to make many typical denial-of-service attacks harder to accomplish.

WTP: Wireless Transaction Protocol
The Wireless Transaction Protocol (WTP), a protocol in the Wireless Application Protocol (WAP) suite, operates efficiently over either secure or non-secure wireless datagram networks. It provides three different kinds of transaction services, namely, unreliable one-way, reliable one-way and reliable two-way transactions. This layer also includes optional user-to-user reliability by triggering the confirmation of each received message. To reduce the number of messages sent, the feature of delaying acknowledgements can be used.
WUSB: Wireless USB
Wireless USB (WUSB) is the wireless extension to USB (Universal Serial Bus) intended to combine the speed and security of wired technology with the ease-of-use of wireless technology. Wireless USB, based on Ultra-WideBand (UWB) defined by IEEE 802.15.3, is capable of sending 480 Mbps or even higher bandwidth at distances up to 3 meters, and 110 Mbps at up to 10 meters. It operates in the 3.1--10.6 GHz band-range and spreads communications over an ultra-wideband of frequencies.

WWAN: Wireless WAN
Wireless Wide Area Network (WWAN) is a wireless network that uses cellular network technologies such as GPRS / CDMA2000 / GSM / CDPD / Mobitex to transfer data. These cellular technologies are offered regionally, nationwide, or even globally and are provided by a wireless service provider. Various computers now have integrated WWAN capabilities with a cellular radio (GSM/CDMA) built in, which allows the user to send and receive data via mobile wireless.
X-band is the bandwith between 7 GHz to 8 GHz, which usually is used by military satellites.

Yagi Antenna
Yagi Antenna is an antenna type that radiates in only a specific direction. Yagi antennas are used only in point-to-point situations.
ZDO: ZigBee Device Object
ZigBee Device Object (ZDO), a protocol in the ZigBee protocol stack, is responsible for overall device management, and security keys and policies. The ZDO is like a special application object that is resident on all ZigBee nodes. ZDO has its own profile, known as the ZigBee Device Profile (ZDP), which the application end points and other ZigBee nodes can access.

ZigBee, defined in the IEEE 802.15.4, is the technology used in the low data rate Wireless Personal Area Network (WPAN) for home control, building automation industrial automation. ZigBee covers up to 330 feet (about 100 meters) in the bandwidth of 20 to 250 kbps.
Zone Paging
Zone Paging is a feature in many paging systems that allows you to page a specific department or an area without disturbing other people.

  • Aeroflex Incorporated - a Cobham company
  • AMETEK Programmable Power, Inc.
  • Anritsu Corporation
  • EDIBON International
  • Leader Electronics Corp
  • SAF Tehnika JSC
  • Sunsight
  • Teamcast