wireless glossary 1


Adjacent Channel Power Ratio

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


Adjacent Channel Leakage Ratio

ACLR is a measure of transmitter performance for W-CDMA. 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 W-CDMA standard.

Acronym Description Explanation
A-bis interface In a GSM network, the interface, usually proprietary to an equipment manufacturer, that is used by the BSC to control the BTS.
AC Authentication Center A device, usually located in the HLR of a GSM system, that manages the authentication or encryption information associated with individual subscribers. Also abbreviated as AUC.
ACIR Adjacent Channel Interference Ratio
ACS Adjacent Channel Selectivity 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 One of the groups spearheading the development of 3G technologies in Europe. ACTS succeeded RACE and is focusing on wideband multiple access techniques.
adaptive equalizer

ADC Analog-to-Digital Converter
adjacent channel interference Out of band power generated in adjacent channels by transmitters operating in their assigned channel. The amount of adjacent channel interference a receiver sees is a function of transmitter and receiver filter characteristics and the number of transmitters operating in the area.
ADPCM Adaptive Differential Pulse Code Modulation
ADSL Asymmetrical Digital Line Subscriber
AGC Automatic Gain Control 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 A downlink control channel used in GSM systems to assign mobiles to a SDCCH for initial assignment.
AIN Advanced Intelligent Network
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.
aliasing A type of signal distortion that occurs when sampling frequency of a signal is less that the Nyquist rate.
AM Amplitude Modulation CW modulation using amplitude variation in proportion to the amplitude of the modulating signal; usually taken as DSB-LC for commercial broadcast transmissions and DSB-SC for multiplexed systems.
AMPS Advanced Mobile Phone System The original standard specification for analog systems. Operates in the frequency range of 800 MHz, with a bandwidth of 30kHz. Used primarily in North America, Latin America, Australia and parts of Russia and Asia.
AMR Advanced Multi Rate Codec During 1999, ETSI standardized this new speech codec 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. AMR was jointly developed by Nokia, Ericsson and Siemens.
analog system A transmission method or way of sending voice, video and data-using signals (such as electricity or sound waves) that are continuously variable rather than discreet units as in digital transmissions. The first networks for mobile phones, built in the 1980s, were analog. Analog systems include AMPS, NMT and ETACS.
ANSI American National Standards Institute A non-profit organization in the US which pursues standardization within the industrial sector. It is also a member of ISO (International Standard Organization). ANSI itself, however, does not establish standards. Instead, it assists in reviewing proposals put forth by various standardizing bodies in the US and accordingly assigns a category code and number after approval.
antenna beamwidth More properly referred to as the half-power beamwidth, this 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 This is the relative gain of the main beam of an antenna pattern to a reference antenna, usually an isotropic or standard dipole.
antenna gain See antenna directivity.
AOA Angle of Arrival A location technique that uses the GPS and a base station to estimate the direction of a user’s device. In a UMTS system, the radio network controller (RNC) uses this information to estimate the location of the device.
APC Automatic Power Control A technique of measuring the performance of a radio channel and adjusting the power of the transmitter to a level appropriate for link characteristics.
ARDIS Advanced Radio Data Information Systems A radio system developed jointly by Motorola and IBM to provide mobile data services. The system is now operated solely by Motorola.
ARFCN Absolute Radio Frequency Channel Numbers A channel numbering scheme used to identify specific RF channels in a GSM radio system.
ARIB Association of Radio Industries and Businesses (Japan) An incorporated body designated by the Ministry of Posts and Communication of the Japanese government to pursue effective radio utilization in the radio communication and broadcast sector. With regard to standardization, ARIB is currently primarily engaged in standardizing procedures for IMT-2000 (next generation mobile communication system) and digital TV broadcasting.
ARQ Automatic Retransmission Request A signal used in digital communications systems used to signal the transmitting device to retransmit a block of data.
ARPU Average Revenue Per User The average of the amount of money spent by customers on wireless services calculated usually on a monthly basis.
ASIC Application-Specific Integrated Circuit An integrated circuit designed to perform a specific set of functions, usually within a specific device.
asynchronous mode A way to send transmissions by starting and stopping transmissions with a code rather than sending transmissions at specific time intervals as in synchronous mode. Asynchronous communication devices do not have to be synchronized with a clocking signal, which is required with synchronous transmission. Also frequently referred to as ATM or Asynchronous Transfer Mode. Can also mean that there are different capacities for data transfer in each direction, for example the old 90/200 baud modems and the new ADSL. See also synchronous mode.
ATM Asynchronous Transfer Mode A technology for broadband transmission of high-capacity telecommunications signals. In addition to high-capacity signal transmission, ATM provides considerable flexibility, since the individual subscriber is able to adapt the capacity of a switched connection to current requirements.
attenuation A decrease in signal magnitude between two points. These points may be along a radio path, transmission line or other device.
attenuator A device specifically designed to decrease the magnitude of a signal transmitted through it.
AUC Authentication Center A device, usually located in the HLR of a GSM system that manages the authentication or encryption information associated with individual subscribers.
authentication Process by which the wireless communications system verifies the identity of a user attempting to make a call, before the call is processed.
average power An indication of the peak power averaged over time. Usually applied to pulsed systems where the carrier power is switched on and off.
AWGN Additive White Gaussian Noise Statistically random radio noise characterized by a wide frequency range with regards to a signal in a communications channel.
AXE An open architecture, Ericsson�s communications platform. A system for computer-controlled digital exchanges that constitute the nodes in large public telecommunications networks. The basis for Ericsson�s wireline and mobile systems.
band-pass filter A radio wave filter having a specific range of frequencies it is designed to pass, while rejecting frequencies outside the pass-band.
bandwidth The information-carrying capacity of a communications channel. Usually expressed in Hertz (cycles per second) for analog circuits and in bits per second (bps) for digital circuits.
base station The central radio transmitter/receiver that maintains communications with a mobile radio telephone within a given range.
BCCH Broadcast Control Channel
BCH Broadcast Channels
BCH code Bose-Chaudhuri-Hocquenghem Code
bearer service A service that enables transport of information between network interfaces.
BER Bit Error Rate A ratio of the number of errors to data bits received on a digital circuit. BER is usually expressed in exponential form.
BERT Bit Error Rate Tester A device used to measure the bit error rate performance of a data circuit.
BLER Block Error Rate 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.
blocking probability 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.
Bluetooth A short range radio technology developed by Ericsson and other companies that makes it possible to transmit signals over short distances between telephones, computers and other devices without having to interconnect them with wires.
bps Bits per Second The units usually used to express data transmission speed; the number of pieces of information transmitted per second.
BPSK Binary Phase Shift Keying A type of phase modulation using 2 distinct carrier phases to signal ones and zeros.
broadband This term has a number of meanings. It was coined originally to describe a channel having more bandwidth than needed to carry a standard voice grade channel. It is also the term for transmission equipment and media that can support a wide range of electromagnetic frequencies. Broadband frequencies can transmit more data and at a higher speed than narrowband frequencies. In general, paging services and traditional voice grade wireless phones are considered narrow-band. High speed data and video communications are usually considered broadband services and employ broadband equipment.
broadcast A transmission sent to many recipients. Most radio transmissions are broadcasts and require the use of encryption to protect privacy.
BS Base Station The equipment on the network side of a wireless communications link. The base station contains the tower, antennas and radio equipment needed to allow wireless communications devices to connect with the network.
BSC Base Station Controller 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 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
BT Bandwidth Time Product
BTA Basic Trading Area A geographic area over which a PCS operator is licensed to provide service. BTAs are a group of counties in metropolitan areas having common financial, commercial and economic ties and were first used to license PCS service in the middle ’90s. BTAs are about the size of a cellular MSA and cross state lines in some instances. BTAs are used by the Rand-McNally corporation to summarize economic data. BTAs are grouped into larger areas called MTAs
BTS Base Transceiver Station Although specifications differ for each system, the BTS effects radio communication 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
C/N carrier-to-noise ratio See carrier-to-noise ratio.
CAI Common Air Interface A set of open standards describing the physical and logical characteristics of a link between a base station and mobile station. These standards are used by infrastructure and handset manufactures to design and build equipment that is capable of interoperating with each others systems.
carrier An RF signal that has an information signal superimposed on it through modulation. Also called a carrier signal.
carrier recovery A technique for extracting the RF carrier from a modulated signal so that it can be reinserted and used to recover the modulating signal.
carrier signal See carrier.
carrier-to-interference ratio The ratio of power in an RF carrier to the interference power in the channel.
carrier-to-noise ratio The ratio of power in an RF carrier to the noise power in the channel.
CAS Call Associated Signaling Signaling required for supervision of a bearer service between two end points. It includes support for the functions of call origination, call delivery, and handover.
CBCH Cell Broadcast Channel
CCDF Complementary Cumulative Distribution Function
CCH Control Channel
CDF Cumulative Distribution Function The cumulative probability that a parameter will be less than a given value X.
CDG CDMA Development Group A technical organization dedicated to developing the CDMA technology and promoting its use world-wide.
CDMA Code Division Multiple Access One of several digital wireless transmission methods in which signals are encoded using a specific pseudo-random sequence, or code, to define a communication channel. A receiver, knowing the code, can use it to decode the received signal in the presence of other signals in the channel. This is one of several “spread spectrum” techniques, which allows multiple users to share the same radio frequency spectrum by assigning each active user an unique code. CDMA offers improved spectral efficiency over analog transmission in that it allows for greater frequency reuse. Other characteristics of CDMA systems reduce dropped calls, increase battery life and offer more secure transmission. See also IS-95.
cdma2000 The name identifying the TIA standard (IS-2000) for third generation technology that is an evolutionary outgrowth of cdmaOne. A radio transmission technology for the evolution of narrowband cdmaOne/IS-95 to 3rd-generation adding up multiple carriers. See also W-CDMA for single carrier/direct spread technology.
cdmaOne Brand name describing a complete wireless system incorporating the IS-95 CDMA air interface.
CDP Code Domain Power A measurement of the power contained in each Walsh coded channel in CDMA signals. The CDP measurement is beneficial in troubleshooting CDMA transmitter designs.
CDPD Cellular Digital Packet Data An open wireless transmission standard allowing two-way 19.2-Kbps packet data transmission over existing cellular telephone channels (AMPS with CDPD capability.) In essence, CDPD technology uses idle network capacity caused by pauses in phone conversations and gaps between calls placed, etc. to transmit data.
CDVCC Coded Digital Verification Color Code
cell The geographic area encompassing the signal range from one base station (a site containing a radio transmitter/receiver and network communication equipment). Wireless transmission networks are comprised of many hexagonal, overlapping cell sites to efficiently use radio spectrum for wireless transmissions. Also, the basis for the term “cellular phone.”
cell splitting The process of splitting a cell into several smaller cells. This us usually done to make more voice channels available to accommodate traffic growth in the area covered by the original cell.
cellular In wireless communications, cellular refers most basically to the structure of the wireless transmission networks which are comprised of cells or transmission sites. Cellular is also the name of the wireless telephone system originally developed by Bell Laboratories that used low-powered analog radio equipment to transmit within cells. The terms “cellular phone” or “cell phone” are used interchangeably to refer to wireless phones. Within the wireless industry, cellular is also used to refer to non-PCS products and services.
cellular handoff In cellular communications, a telephone call is switched by computers from one transmitter to the next, without disconnecting the signal, as a vehicle moves from cell to cell. The mobile remains on a specific channel until signal strength diminishes, then, is automatically told to go to another channel and pick up the transferred transmissions there.
cellular mobile telephone system System where each geographic area is covered by a base station. This area is known as a cell. Each telephone in the cell communicates with the base station. If the phone moves to another cell, the call is automatically transferred to the base station in the new cell.
CELP Code-Book Excited Linear Predictive
CEPT Committee of European Posts & Telephones A European regulatory body responsible for coordinating telecommunications within Europe.
CGSA Cellular Geographic Service Area A general term used to describe the physical area over which a cellular carrier is licensed to provide service. See also MSA, RSA, MTA, BTA, EA and REAG.
channel A general term used to describe a communications path between two systems. They may be either physical or logical depending on the application. An RF channel is a physical channel, whereas control and traffic channels within the RF channel would be considered logical channels.
channel coding The application of forward error correction codes to an RF channel to improve performance and throughput.
CHTML (cHTML) Compact HTML Version of the hypertext markup language used by NTT DoCoMo’s i-mode service.
CIF Common Intermediate Format A video image format using 352 horizontal pixels and 288 vertical lines. The format is adopted in multimedia communication standards.
circuit switched A switched circuit is only maintained while the sender and recipient are communicating, as opposed to a dedicated circuit which is held open regardless of whether data is being sent or not.
clock recovery The process of extracting the timing signals from a digitally modulated carrier wave. The recovered clock signal is then used to decode and further process the data.
CODEC Coder/Decoder An amalgam of the terms “Coder” and “Decoder”. It generally signifies the encoding device/module which carries out highly efficient conversion processing from the basic digital signal to a compressed signal during digitalization of voice and picture signals. Encoding specifications for the voice CODEC and image CODEC are stipulated by the G-series and H-series ITU-T recommendations, respectively. In the case of mobile communication, encoding specifications are established by the concerned standardizing bodies.
coding gain The effective gain, usually in dB, that coding provides over an uncoded signal. Coding gain is usually measured as the dB difference in C/N ratios between a coded and uncoded signal producing the same BER.
coherent detection Also referred to as coherent demodulation, this is a technique of phase locking to the carrier wave to improve detection. Knowledge of the carrier phase improves demodulator performance.
companding Compressing and Expanding
control channel A channel, usually logical, used to send administrative and supervisory signals between a base station and a mobile station.
core network In a wireless communications network, the physical infrastructure that ties together all the radio access equipment. In 1G and 2G networks, the core network is circuit-switched. In 2.5G and 3G data networks, the core network will be IP packet-based.
core network interface In 3G UMTS, the terrestrial core network infrastructure connected to the RAN through the Iu interface; for example, the Internet and the public switched telephone network (PSTN). The gateway device for this activity is usually called a mobile switching center (MSC) or mobile multimedia switch.
COST-231 ETSI propagation model for 2 GHz applications.
coverage area The geographical reach of a mobile communications network or system.
coverage hole An area within the radio coverage footprint of a wireless system in which the RF signal level is below the design threshold. Coverage holes are usually caused by physical obstructions such as buildings, foliage, hills, tunnels and indoor parking garages.
CPM Continuous Phase Modulation
CRC Cyclic Redundancy Code
CT-2 Cordless Telephone 2
CT-3 See DECT.
CTIA Cellular Telecom Industry Association The membership-based association, located in Washington, D.C., represents the interests of the wireless telecommunications industry.
CW Continuous Wave The term commonly gives to an unmodulated RF carrier.


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