wireless terms 3


International Mobile Station Equipment Identity

Internet Mode

A wireless service launched in Japan in spring 1999 by NTT DoCoMo. The service is accessed by a wireless packet network (PDC-P) and the contents are described in a subset of the HTML language.

Internet Messaging Access Protocol

A remote mailbox access protocol. It enables efficient operation such as downloading only essential data by first acquisitioning the e-mail header prior to actual e-mail download. This feature makes the protocol well suited to remote environments.

Acronym Description Explanation
I In-Phase For PSK modulation, the reference phase channel. See also Q.
IF Intermediate Frequency The operating frequency in superheterodyne receivers where amplification, filtering and level control prior to demodulation is accomplished.
IMSI International Mobile Station Identity

IMT-2000 International Mobile Telecommunication 2000 A term used by the International Telecommunication Union, a United Nations agency, to describe the third generation mobile telephony due to be ready in 2000. Can also be applied to mobile telephone standards that meet a number of requirements in terms of transmission speed and other factors.
IMTS Improved Mobile Telephone Service
IN Intelligent Network 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.
Internet capability Functionality in a wireless network enabling access to the Internet for web page viewing and e-mail purposes.
IP Internet Protocol A set of instructions defining how information is handled as it travels between systems across the Internet.
IPR Intellectual Property Rights Also known as patents, these are the rights of an inventor or assignee to develop and commercialize an invention and license it, usually for a fee, to other manufacturers.
IPv6 Internet Protocol version 6. The latest IP version. Address exhaustion is prevented by means of a long address field, thereby enabling further Internet expansion. In addition, security and mobility are built into the protocol. Currently utilized IP addresses are almost all IPv4, and with the present rate of Internet growth this type of address will be exhausted by 2010. IPv6 on the other hand enables 10 to the 29th power more available addresses than the previous IPv4.
IS-136 EIA Interim Standard 136 – NADC with Digital Control Channels The North American digital mobile telephony standard based on TDMA technology. It is the version of the TDMA specification resulting in a fully digital 2nd generation system and is backward compatible with analog AMPS. See also TDMA and D-AMPS.
IS-2000 EIA Interim Standard 2000 (see cdma2000) A standard for current CDMA systems providing a migration path to 3G services.
IS-41 Inter-network connection protocol for connecting systems based on both analog and digital US standards. Inter-network connection protocol for connecting systems based on both analog and digital US standards.
IS-54 EIA Interim Standard for U.S. Digital Cellular 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.
IS-95a EIA Interim Standard 95 (see cdmaOne) The original digital mobile telephony standard based on CDMA technology. See also CDMA.
1S-95b Upgraded version of IS-95a that increases the maximum data rate to 115.2 kb/s.
ISDN Integrated Services Digital Network. A technology offering switched and fixed high speed transmission of voice, data and video through the existing telephone infrastructure. The service is based on 1 or more 64 kbps digital channels and does not use traditional modems.
ISI Inter-Symbol Interference 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.
ITU International Telecommunications Union A United Nations agency that deals with telecommunications issues.
IWF Interworking Function 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.
jitter Variation in the amount of time that it takes packets to traverse the network and arrive at a destination.
kHz kiloHertz A radio frequency measurement (one kilohertz = one thousand cycles per second).
LAI Location Area Identity 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.
LAN Local Area Network A small data network covering a limited area, such as within a building or group of buildings.
LAS-CDMA Large Area Synchronized Code Division Multiple Access A technology developed by LinkAir that offers 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 for phase 2 of the 1xEV standards.A LAS-CDMA TDD variant is compatible with systems such as TD-SCDMA.
Lee’s model 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.
line speed Data transmission rate over a physical or wireless medium, typically given in number of bits per second.
link The radio connection between a transmitter and a receiver.
link budget 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
LNA Low Noise Amplifier
location registration One of several computer databases used to maintain location and other information on mobile subscribers. See HLR and VLR.
logical channel 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 loss of signal
LOS line of sight A description of an unobstructed radio path or link between the transmitting and receiving antennas of a communications system.
LPA linear power amplifier 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.
LPC Linear Predictive Coding
LSB Least Significant Bit In a binary coding scheme, the bit having the least numerical value. Analogous to the units position in a decimal number.
lu Standardized interface between a Radio Network Controller Network and Packet Subsystem (e.g. RNC-3GSGSN).
lub Interface between a Base Station and Radio Network Controller.
lur Open RNC-RNC interface.
MAC Medium Access Control
macro cell 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 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.
MAP Mobile Application Part
MASHO Mobile Assisted Soft Handoff See MAHO.
MC-CDMA Multi-Carrier Code Division Multiple Access Typically, this means the combination of three IS-95 carriers to form one wideband carrier. It is an evolution of IS-95 for third generation systems. Also called cdma2000. The current nomenclature is temporary, with a formal name for this technology to be determined under 3GPP2.
Mcps Mega Chips per Second A measure of the number of bits (chips) per second in the spreading sequence of direct sequence spreading code.
MHz Megahertz A unit of frequency equal to one million hertz or cycles per second. Wireless communications occur in the 800 MHz, 900 MHz and 1900 MHz bands.
micro cell A base station with a very small coverage area designed to provide service in areas having a very high density of mobile subscribers. Microcells are traditionally used in convention centers, airports and similar areas.
MIN Mobile Identification Number
m-law companding A type of non-linear (logarithmic) quantizing, companding and encoding technique 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.
MM Mobility Management Functions that track the location of a mobile station as it moves within a given area.
MMM Mobile Media Mode The WWW:MMM logo is a marketing innovation comprising a unifying industry-wide marketing symbol representing leading edge web-based products and services.
MMS Multimedia Messaging Service MMS is a new standard that is being defined for use in advanced wireless terminals. The service concept is derived from Short Message Service and allows for non-real-time transmission of various kinds of multimedia contents like images, audio, video clips, etc. As a further evolution of the current text mail, for example, electronic postcards, audio/video clips, etc. can be sent.
mobile phone network 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.
MOS Mean Opinion Score
MPE multi-pulse excited A multi-pulse process for determining the position and amplitude of sample pulses in a speech codec.
MPEG Moving Picture Experts Group The group that has defined the standards for compressed video transmission. Can also refer to the file format itself.
MPEG4 Moving Picture Experts Group Compression Standard Version 4. MPEG4 is a technology for compressing voice, video and related control data and is one of the MPEG (Moving Picture Experts Group) international standards. It is currently a focus of attention due to the fact that it enables high speed and stable video transmission even in heretofore difficult environments such as mobile communication. Incorporation of this leading edge technology will imbue 3G terminals with a rich multimedia capability.
MS Mobile Station The term used to describe the customer terminal in a wireless network.
MSA Metropolitan Statistical Area 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 In a binary coding scheme, the bit having the greatest numerical value. Analogous to the left-most numeric position in a decimal number.
MSC Mobile Switching Center The location providing the mobile switching function in a second generation network wireless network. The MSC switches all calls between the mobile and the PSTN and other mobiles.
MSK Minimum Shift Keying
MTA Major Trading Area A geographic area over which a PCS operator is licensed to provide service. MTAs are a group of BTAs having common financial, commercial and economic ties and were first used to license PCS service in the middle ’90s. MTAs can be many times larger a cellular MSA and can cross multiple state lines in some instances. MTAs are used by the Rand-McNally corporation to summarize economic data. MTAs are one of the largest licensing areas used by the FCC.
MTSO Mobile Telephone Switching Office The location providing the mobile switching function in a first generation wireless network. The MTSO switched all calls between the mobile and the PSTN and other mobiles.
multiple access 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.
NADC North American Digital Cellular
NAM Number Assignment Module The programmable module in an AMPS analog phone used to contain the MIN, ESN, home system ID and other information.
N-AMPS Narrowband Advanced Mobile Phone System Combines the AMPS transmission standard with digital signaling information to effectively triple the capacity of AMPS while adding basic messaging functionality.
NM Network Management
NMC Network Management Center An operations center used to manage network resources such as the MSC, location registers and base stations.
NML Network Management Layer
NMT Nordic Mobile Telephony 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 An early cellular system developed and operated in northern Europe utilizing the 450 MHz band.
node A point of connection in a network. A node is often a device on the network that can process a transmission or forward it to anogther node.
Node B 3G UMTS base station transceiver. Node B (also called the base station controller or radio base station) provides the gateway between the handset/RF interface and the radio network controller via the Iub interface.
noise figure 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.
NRZ Non Return to Zero
NSS Network Switching Subsystem
Nyquist rate 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.
OAM&P Operations, Administration, Maintenance & Provisioning Center An operations center used to operate, administer, maintain and provision the network.
OCQPSK Orthogonal Complex Quadrature Phase Shift Keying
OFDM Orthogonal Frequency Division Multiplex
OMC Operations & Maintenance Center A location used to operate and maintain a wireless network.
OQPSK Offset Quadrature Phase Shift Keying 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.
ORFS Output Radio Frequency Spectrum 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.
OSI Open System Interconnect
OVSF Orthogonal Variable Spreading Function
PA Power Amplifier 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.
PABX Private Automatic Branch Exchange A customer premise telephone switching system capable of interfacing to a telephone central office with trunk groups and routing calls based on a 3 or 4 digit telephone extension number.
packet A piece of data transmitted over a packet-switching network such as the Internet. A packet includes not just data but also address information about its origination and destination.
packet radio A radio system that operates by sending data in packets.
PACS Personal Access Communications System
PAD Packet Assembler/Disassembler The part of a packet transmission system that segments the transmit data into packets and returns the receive data to longer messages. [5]
pad See attenuator.
PAM pulse amplitude modulation A technique for encoding the samples of an analog waveform as part of the PCM process. Also used to display the amplitude of QAM signals in an eye diagram.
path loss The amount of loss introduced by the propagation environment between a transmitter and receiver.
PBX Private Branch Exchange An exchange system used in companies and organizations to handle internal and external calls.
PCH Paging Channel
PCIA Personal Communications Industry Association A leading international trade association representing the personal communications services (PCS) industry. Its primary objective is to advance regulatory policies, legislation, and technical standards in this industry.
PCM Pulse Code Modulation
PCN Personal Communications Network 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 Communications Services Generally, a marketing term used to describe 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.
PCS Personal Communications System The infrastructure used to provide personal communications services.
PCU Packet Control Unit A device that must be added to older GSM base stations if they are to carry GPRS traffic. Functions include converting packet data into a format that can be transferred over the air interface, managing radio resources,and implementing quality of service (QoS) measurements.
PDA Personal Data Appliance/Assistant Also known as Personal Digital Appliance.
PDC Personal or Pacific Digital Cellular A Japanese standard for digital mobile telephony in the 800 MHz and 1500 MHz bands. To avoid the previous problem of lack of compatibility between the differing types of earlier analog mobile phones in Japan (i.e. NTT type and US developed TACS type), digital mobile phones have been standardized under PDC. In the case of the PDC standard, primarily six channel TDMA (Time Division Multiple Access) technology is applied. PDC, however, is a standard unique to Japan which renders such phone units incompatible with devices which adopt the more worldwide prevalent GSM standard. Nevertheless, digitalization under the standard enables ever smaller and lighter mobile phones which in turn has spurred market expansion. As a result, over 93% of all mobile phones in Japan are now digital.
PDF Probability Density Function
PHP Personal Handy Phone The mobile hand-set used with the Japanese Personal Handy Phone system.
PHS Personal Handy Phone System
physical channel The actual radio channel that carries the various logical and traffic channels in a wireless system.
pico cell Very small cell in a mobile network for boosting capacity within buildings.
pilot pollution 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 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 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 A European term used to describe the GSM system.
PMR Private Mobile Radio Generally for use within a defined user group such as the emergency services or by the employees of a mining project.
PN Pseudo-Noise Historically, the Ministry of Post, Telecommunications and Telegraph. Now a term to describe the incumbent, dominant operator in a country, many of which are being or have been privatized.
PNCQPSK Pseudo-Noise Complex Quadrature Phase Shift Keying The spreading technique that uses basic complex scrambling and PN signals for Is and Qs. For more information see Agilent application note “HPSK Spreading for 3G”.
point to point A direct link between two network nodes.
POCSAG Post Office Code Special Advisory Group
power control 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.
power spectral density Power normalized to 1 Hz. Knowing the power spectral density and system bandwidth, the total power can be calculated.
PQA Palm Query Applications
PRBS Pseudo-Random Binary Sequence
PRMA Packet Reservation Multiple Access
PSD Power Spectral Density See power spectral density.
PSK Phase Shift Keying 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 Standard domestic and commercial phone service.
Q Quadrature-Phase The quadrature phase channel in a phase shift keyed system having more that 2 phase states.
QAM Quadrature Amplitude Modulation Ã?
QCIF Quarter CIF (1/4 CIF). 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.
QoS quality of service A measure of the quality of the signal transmitted over the RF channel. In some systems, the QoS measurement is used to dynamically adjust operational parameters such as transmitter power levels and coding rates.
QPSK Quadrature Phase Shift Keying Ã?
RAB Radio Access Bearer
RACE Research in Advanced Communications Equipment
RACH Random Access Channel The channel used by mobiles in GSM and W-CDMA systems to attempt to gain access to the system when first attaching to it.
radio port The T1P1 PCS architecture model equivalent to the BTS.
RAN Radio Access Network
random access 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 fading A type of signal fading caused by independent multipath signals having a Rayleigh PDF.
RC 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. For more information see Agilent application note “Performing cdma2000 Measurements Today”.
REAG Region 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 ’90s. REAGs are very large, with 6 REAGs covering the entire continental United States.
receive diversity The process of providing two independent receiving systems and spatially separated antennas to overcome fading effects on the radio signal.
registration This 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.
Repeater Receives radio signals from the base station. They are then amplified and re-transmitted to areas where radio shadow occurs. Repeaters also work in the opposite direction, i.e. receiving radio signals from mobile telephones, then amplifying and re-transmitting them to the base station.
reuse factor Also known as frequency reuse factor, is the number of distinct frequency sets used per cluster of cells.
RF radio frequency Electromagnetic waves in the frequency range of 30 kHz to 300 GHz. [2]
RNC Radio Network Controller under the UMTS system. A complex network element of the RAN that connects to and co-ordinates as many as 150 base stations in W-CDMA systems. It is involved in managing activities such as hand-over of active calls between base stations.
Roaming Within your home network, this means that your mobile phone automatically sets up communication procedures with different radio base stations when on the move. International roaming means that you can use networks other than your own when traveling abroad.
Router A data switch that handles connections between different networks. A router identifies the addresses on data passing through the switch, determines which route the transmission should take and collects data in so-called packets which are then sent to their destinations.
Routing The forwarding of data packets in packet-switched networks, to the intended address.
RPE-LTP Regular Pulse Excited-Long Term Prediction A type of speech coding using regularly spaced pulses in an excitation frame and a long term predictor to model the fine structure (pitch).
RSA Rural Service Area A geographic area 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 service Rural areas in the latter ’80s. RSAs cross state lines in some instances and were developed during a public rule making process at the FCC in 1987 and 1988..
RSSI Received Signal Strength Indication
S/I signal-to-interference ratio
S/N signal-to-noise ratio
SACCH Slow Associated Control Channel
sampling The first 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 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.
SCCH Signaling Control Channel
SCH Synchronization Channel A logical channel used by mobile stations to achieve time synchronization with the network. Used in GSM, cdma2000, and W-CDMA systems. [1]
SDCCH Slow Dedicated Control Channel
SDH Synchronous Digital Hierarchy An international standard for synchronous optical transmission. This standard allows the world-wide connection of digital networks.
SDMA Space Division Multiple Access Also known as multiple beam frequency reuse, this technique employs spot beam antennas to reuse frequencies by pointing the antenna beams using the same frequency in different directions.
SFHMA Slow Frequency Hopped Multiple Access
shadow fading A phenomenon that occurs when a mobile moves behind an obstruction and experiences a significant reduction in signal power.
SHF Super High Frequency
Signal Booster Compensates for loss of effect (weakening of the signal in the co-axial cable) between the outer antenna and the phone. Applies to both incoming and outgoing signals.
SIM Card Subscriber Identity Module Card
slow fading 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.
SMR Specialized Mobile Radio
SMS Short Messaging Service (Service Management System)
SNR Signal-to-Noise Ratio
spread spectrum A term used to describe a system that uses spectrum spreading techniques in its operation.
SR Spread Rate Spread rate is also known as the chip rate and is the rate of the digital code used to spread the information. The spreading rate is typically at least 100x the information rate.
SS Spread Spectrum See spread spectrum.
SS7 Signal System 7
SSD Shared Secret Data
STD Selective Transmit Diversity
supplementary services 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 Owned by Ericsson, Nokia, Motorola, Panasonic and Psion, Symbian creates an advanced, open, standard operating system – Symbian OS – for its licensees. Symbian OS is designed for next-generation mobile phones and enables a broad, international, developer community. Phones using Symbian OS include the Ericsson R380 and Nokia 9210.
symmetric In communications networks, providing the same data rate in each direction.

TAMS Temporary Mobile Station Identity
TCH Traffic Channel 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.
TCH/F Traffic Channel – full rate
TCH/H Traffic Channel – half rate A traffic channel using half rate voice coding.
TCM Trellis Code Modulation A type of channel coding that, unlike block and convolutional codes, provide coding gain by increasing the size of the signal alphabet and use multi-level phase signalling.
TCP Transmission Control Protocol TCP/IP is the standard communications protocol required for computers communicating over the Internet. To communicate using TCP/IP, computers need a set of software instructions or components called a TCP/IP stack.
TDD Time Division Duplex A duplexing technique dividing a radio channel in time to allow downlink operation during part of the frame period and uplink operation in the remainder of the frame period. See also duplex.
TDMA Time Division Multiple Access A technology for digital transmission of radio signals between, for example, a mobile telephone and a radio base station. In TDMA, the frequency band is split into a number of channels which in turn are stacked into short time units so that several calls can share a single channel without interfering with one another. Networks using TDMA assign 6 timeslots for each frequency channel. TDMA is also the name of a digital technology based on the IS-136 standard. TDMA is the current designation for what was formerly known as D-AMPS. See also IS-136 and D-AMPS.
TDN Temporary Directory Number
TD-SCDMA Time Division Synchronous Code Division Multiple Access A new technology developed by Siemens and the China Academy of Telecommunication Technology. 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
terminal In wireles communications, used synonymously with such terms as mobile handset, mobile station, user equipment, or mobile device.
TIA Telecommunications Industry Association (U.S.)
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.
TOA Time of Arrival 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.
transceiver A transmitter and receiver contained in one package. A 2-way radio or cell phone is an example of a transceiver.
transmission plane In a wireless communications network, the transmission plane consists of layered protocols that transfer user information and provide control procedures such as flow control and error correction.
transmit diversity A technique utilizing multiple transmit stations to originate the downlink signal and improve performance. The station used is determined by either a fixed pattern or a quality measurement at the mobile. See also TDTD, STD and TSTD.
TSTD Time Switched Transmit Diversity
TTA Telecommunications Technology Association (Korea) A telecommunications standards setting body in Korea.
TTC Telecommunications Technology Committee (Japan) A private-sector corporate body established in 1985 to prepare domestic standards relevant to Japanese telecommunications.
tunneling Sending data intended for a private network through the public network using a temporary, secure path. Tunneling enables virtual private networks to send data across the Internet, for example. Several protocols exist for tunneling, including the point-to-point protocol (PTPP) developed by Microsoft and others, and the generic routing encapsulation (GRE) protocol developed by Cisco Systems.
UDP User Datagram Protocol An alternative to TCP used widely in streaming audio and video applications. UDP does not insist on retransmission of dropped packets, thus it uses bandwidth more efficiently in applications with less need for error detection and correction.
UE User Equipment In a 3G UMTS network, User Equipment (also called the mobile station or handset) includes mobile cellular telephones, handheld personal digital assistants (PDAs), and cellular modems connected to PCs.
UHF Ultra High Frequency The RF spectrum between 300 MHz and 3 GHz.
UL Uplink See uplink.
UMTS Universal Mobile Telecommunications System Third generation telecommunications system based on W-CDMA DS.
UNIX A computer operating system. UNIX is designed to be used by many people at the same time and has TCP/IP built-in. It is a very common operating system for servers on the Internet.
uplink The transmission path from the mobile station up to the base station.
UPT Universal Personal Telecommunications
USIM Universal Subscriber Identity Module This upgrade to the SIM card enables use with IMT-2000.
UTRA UMTS Terrestrial Radio Access
UTRAN UMTS Terrestrial Radio Access Network The radio access network based on the UTRA standard.
UUT Unit Under Test An acronym describing some type of electrical apparatus connected to test instrumentation. The apparatus can range from a simple circuit a complex subsystem such as a mobile phone, base station or MSC. See also DUT.
UWC Universal Wireless Consortium Body 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.
VAD voice activity detector 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.
VHF Very High Frequency
VLR Visitor Location Register
VOIP Voice Over Internet Protocol A technology for transmitting ordinary telephone calls over the Internet using packet-linked routes. VoIP is not simply for voice over IP, but is designed to accommodate two-way video conferencing and application sharing as well.
VPN Virtual Private Network
VSELP Vector Sum Excited Linear Predictive A type of speech coding using an excitation signal generated from three components: the output of a long term or pitch filter and two codebooks. VSELP was used in the IS-54 standard and operated at a rate of 8 kbps.
W3C World Wide Web Consortium A sector-wide body which promotes standardization of WWW technology. Major Internet related vendors are consortium members, and to date the body has standardized a range of crucial technologies including HTTP, HTML,
Walsh Code 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. For more information see Agilent application note “Performing cdma2000 Measurements Today”.
WAN Wide Area Network A network of computers and interconnected LANs, typically spread out over a large area.
WAP Wireless Application Protocol A free, unlicensed protocol for wireless communications that makes it possible to create advanced telecommunications services and to access Internet pages from a mobile telephone. WAP is a de facto standard that is supported by a large number of suppliers. See also
WCA Wireless Communications Association The Wireless Communications Association represents the fixed broadband wireless access industry worldwide. It’s 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 See W-CDMA.
W-CDMA Wideband-Code Division Multiple Access
WDM Wavelength Division Multiplexing A new technology that uses optical signals on different wavelengths to increase the capacity of fiber optic networks in order to handle a number of services simultaneously.
WLAN Wireless Local Area Network A wireless version of the LAN. Provides access to the LAN even when the user is not in the office.
WLL Wireless Local Loop A wireless connection of a telephone in a home or office to a fixed telephone network.
WML Wireless Markup Language A markup language developed specifically for wireless applications. WML is based on
WOS Wireless Office Systems A technology that allows the user to transfer calls to a mobile telephone.
WPABX Wireless Private Automatic Branch Exchange 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.


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