Glossary

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1G - First Generation Mobile Phone Systems
Analog systems designed for voice communication using the AMPS, TACS and NMT standards and have largely been replaced by 2G systems.

2G - Second Generation Mobile Phone Systems
2G systems are digital and provide voice, fax and limited data transfer communication and value-added services. Present systems are evolving to increase data rates using new technologies. 2G systems include GSM, US-TDMA (IS-136), cdmaOne (IS-95 US-CDMA), PCS and PDC. US-TDMA and PDC offer backward compatibility with 1G analog technology.

3G - Third Generation Mobile Telecommunications
A new generation of wireless systems which provide high-speed data transmission (144 kbps and higher) and Internet Protocol (IP) based services in fixed, portable, and mobile environments. 3G systems include three operating modes - CDMA2000, W-CDMA and TD-SCDMA.

3GPP - Third Generation Partnership Project
3GPP stands for the "3rd Generation Partnership Project," a collaboration agreement that was established in December 1998. The collaboration agreement brings together a number of telecommunications standards bodies which are known as "Organizational Partners". The current Organizational Partners are ARIB, CWTS, ETSI, T1, TTA, and TTC. Full information about 3GPP is available at: http://www.3gpp.org/.

Access
The link between customer and telecoms network. A variety of technologies are used including copper wires, fibre optics, mobile, microwave and satellite.

Asymmetric Digital Subscriber Line (ADSL)
Digital technology to allow broadband service over ordinary copper telephone lines. Transmission capacity is greater from network to customer (c1.5Mbps) than customer to network, hence asymmetric.

Analogue
Information conveyed in a continuously varying electronic signal, unlike a digital signal which varies between two constant values. The first mobile networks were analogue.

Analogue Signal (AS)
A signal sent using an analogue system ie with no specified limit on transmitted data.

Antenna
Device used for transmitting or receiving electromagnetic radiation at radio frequencies.

Attenuation
Loss of signal strength in a lightwave, electrical, or radio signal that is usually related to the distance the signal must travel. For example, fiber-optic transmission must be regenerated approximately every 30 miles. Radio signal attenuation may be caused by atmospheric conditions, sun spots, antenna design or positioning, and line-of-sight obstacles. Usually expressed as a ratio in decibels (Db).

Advanced Mobile Phone Service (AMPS)
Analogue cellular telephone technology is used mainly in the US. Operates in the 800Mhz band frequency. This was the original American analogue cellular radio system used by AT&T (the digital enhancement was originally called D-AMPS, and is now known as TDMA). About 40% of Latin American and 25% of North American subscribers are on AMPS. The bulk of AMPS migration is to CDMA-One and TDMA.

Backbone
High capacity part of networks, often covering long distances.

Bandwidth
Range of frequencies occupied by a signal. (For example, a telephone conversation only requires 3KHz of bandwidth while hand television signals require about 3MHz of bandwidth.) The 'necessary bandwidth' is the amount of spectrum required to transmit the signal without distortion or loss of information. In analogue systems, it is measured in cycles per second (Hertz) and in digital systems in binary bits per second (bps).

Base Station
Fixed radio transmitter/receiver which electronically relays signals to and from mobile terminals or handsets within a given range (a cell). Houses the equipment needed to set up and complete calls on cellular phones, ie FM radio transmitter and receiver, antenna, and computer. The base station works with the subscriber's handset and the Mobile Telephone Exchange to complete a call.

Bit
Binary Digit. Any digital transmission is composed of a series of bytes, each of which comprise eight bits. A bit is the smallest component unit of any electronic message and functions like an on/off switch using 1s and 0s. The combination of on and off in any one byte determines the content of information sent in that byte.

Bits Per Second (bps)
Rate at which individual bits are transmitted across a communications link or circuit. One thousand bps is 1Kbps, and one million bps is 1Mbps or 1Mbit/s.

Bluetooth
Short-range wireless connection standard enabling seamless voice and data transmission via short range (up to 10 metres) radio signals. Its aim is to link a wide range of computers, electronics and telecoms devices. The technology uses a low-power, two-way radio link, which is built into a microchip. It is a global initiative by Ericsson, IBM, Intel, Nokia and Toshiba to set a standard for cable-free connectivity between mobile phones, mobile PCs, handheld computers and other peripherals.

Bottleneck
1) Capacity constraint that may limit traffic carried on the network during peak load conditions.

2) In the US, part of the local loop which is monopolized is known as a bottleneck, because only one carrier provides the service. Thus it is a regulatory term and affects how prices are regulated.

Broadband
Transmission capacity with sufficient bandwidth to permit combined provision of voice, data and video. Unlike voice communication which requires transmission of relatively small amounts of information, video and multimedia services require transmission of large amount of information.

Broadband Network
Network having a broadband capacity capable of transmitting voice, image, video and data signals at a rate in excess of 1.5Mbps. See Narrowband Network; Wideband Network.

BWA (Broadband Wireless Access)
Service providing two-way broadband, data, voice, multimedia and information services using (mostly) millimetre wave radio links. LMDS [Local Multi-point Distribution Service] is a technology that enables BWA.

Byte
Standard unit for transmitting information from one electronic source to another. One byte comprises eight bits.

Cable TV or Community Antenna Television (CATV)
Cable TV is a service that distributes a wide range of television programmes to homes of subscribers from a central facility through co-axial cable networks. See also Cable.

Caller Line Identification (CLI)
Service that allows a customer to see the number of the caller before answering the call.

Carrier (CRX)
Long-distance company which primarily uses its own transmission facilities to carry calls, as opposed to resellers who lease or buy most or all of their transmission facilities from the carriers.

CDMA (Code Division Multiple Access) also known as CDMA-One
CDMA, one of the three wireless telephone transmission technologies, takes an entirely different approach from GSM and the similar TDMA. CDMA, after digitizing data, spreads it out over the entire bandwidth it has available. Multiple calls are overlaid over each other on the channel, with each assigned a unique sequence code. CDMA claims superiority over TDMA in terms of quality, capacity and security. CDMA was commercialised by Qualcomm of the US and is most widely used in that market. See also CDMA2000, FDMA. cdmaOne Networks using the 2G CDMA standard developed by Qualcomm and its partners. The first network using this standard was built by Hutchison in Hong Kong in 1995, with US roll-outs beginning in 1996. There are standards for the cdmaOne air interface: IS-95A and IS-95B, which offers higher data rates than the former.

CDMA2000
3G technology developed by Qualcomm of the US. This is in competition with W-CDMA, developed by the GSM community as the worldwide standard for 3G mobile. An evolutionary upgrade from cdmaOne.

CDMA2000 1x
First step in the evolution to 3G, which improves packet data transmission capabilities and speeds in the network, and also boosts voice capacity by nearly two times over today's CDMA capacities.

CDMA2000 1xEV
CDMA2000 1xEV represents the second step in the evolution of CDMA2000 and will bring data rates of up to 2Mbps to the network. EV stands for evolution. 1xEV can be deployed either on its own as a mobile data network, or in conjunction with CDMA2000 1x. 1xEV is developed in two stages, the first offering support for data only, the second combining data and voice.

CDMA2000 3x
Full 3G version of CDMA2000. Technology is similar to CDMA2000 1x, but the peak data rate is 2Mbps.

CeBIT
World's largest telecommunications exhibition, held in Hannover in Germany each spring.

Cell
Geographic area in cellular telephone systems in which all cellular transmissions are controlled by a single cell site.

Cell Switching
Feature that enables a caller to move from one location to another without losing the connection. The cellular system is designed to switch calls to a new call without a noticeable drop in the connection. While not noticeable in voice communications, the 300 milliseconds required for cell switching can cause problems in data transmission.

Cellular Radio
Radio frequency-based communication service over which voice or data is transmitted. The service area is divided into cells each served by a transmitter.

Channel
Telecommunications path of a specific capacity and/or speed between two or more locations on a network. The channel may be established via wire, radio (microwave), fibre or a combination of the three.

Circuit Switching
Traditional network design in which the switch keeps a path open between the caller and called party for the duration of the call. Most voice calls are circuit switched to maintain real-time transmission while many data calls are packet switched for greater efficiency at the expense of some transmission delays.

Convergence
The coming together of a number of different technologies and information including the Internet and devices such as television, mobile phones and PCs. See also Fixed to Mobile Integration (FMI).

Copper line
Main transmission medium used in telephony networks to connect a telephone or other apparatus to the local exchange. Copper lines have relatively narrow bandwidth and so have limited ability to carry broadband services such as video unless combined with an enabling technology such as ADSL.

Coverage
Geographical reach of a mobile phone network or system.

D-AMPS (Digital Advanced Mobile Phone Service)
Cellular phone service, using the TDMA technology. Analogue systems can be upgraded to D-AMPS.

Dark Fibre
Inactive fibre-optic cable without electronics or optronics.

Deregulation
Removing regulatory barriers governing service or provider, thereby encouraging free competition.

Dial-up
The most common way of connecting to the Internet. The user's computer is connected to a modem, which connects to another computer via the PSTN.

Digital (Communications)
Method that uses a series of binary (0s and 1s) signals for sound, video, computer data or other information. Digital communications technology generally permits higher speeds of transmission with a lower error rate than analogue technology.

Digital Cable
Digital Cable Delivery of digital broadcast signal by way of a cable network.

Digital Cellular System 1800/ 1900 (DCS1800/ 1900)
In the UK and parts of Asia, the standard adopted for PCN is called DCS1800. Operates in the 1800MHz range, accommodating 150MHz compared with 50MHz for GSM. Has enhanced roaming capabilities allowing roaming between operators nationally. DCS1900 is the PCN standard in North America.

Digital European Cordless Telecommunications (DECT)
A wireless, short-term transmission standard used in Europe, often for cordless telephones and, potentially, for Net devices like smart home gateways.

Digital Network
Telecoms network in which information is converted into a series of distinct electronic pulses and then transmitted as a digital bit stream.

Digital Subscriber Line (DSL)
Technology for bringing high-bandwidth information to homes and small businesses over ordinary copper telephone lines. xDSL refers to different variations of DSL, such as ADSL, HDSL, SDSL and VDSL.

Dual Band
Dual band mobile phones work on more than one network.

ECSD (Enhanced Circuit Switched Data)
ECSD is likely to be the less popular of the two EDGE options available, focused mainly on applications that require a continuous stream of data.

EDGE (Enhanced Data GSM Environment)
EDGE is one of the three technology upgrade options available to GSM networks, along with GPRS and HSCSD. EDGE is designed to deliver data at rates up to 384Kbps and enable the delivery of multimedia and other broadband applications to mobile phone and computer users. The EDGE standard is built on the existing GSM standard, using the same TDMA frame structure and existing cell arrangements. There will be two versions of EDGE, ECSD and EGPRS.

EFR (Enhanced Full Rate)
Technology which improves the quality of calls made on a digital mobile network, to the extent that they are comparable to fixed line calls. It is achieved through more efficient use of bandwidth.

EGPRS (Enhanced General Packet Radio Systems)
EGPRS enhances the speeds of GPRS and is targeted at improving Internet download times.

EMI (Electromagnetic Interference)
Undesirable response in the operation of electronic systems or equipment due to electromagnetic energy.

Erlang
Unit of traffic volume corresponding to the number of simultaneous calls in progress at any given time or averaged over a period of time.

FDMA (Frequency division multiple access)
Division of the frequency band allocated for wireless cellular telephone communication into 30 channels, each of which can carry a voice conversation or, with digital service, carry digital data. FDMA is a basic technology used in the analogue AMPS the most widely-installed cellular phone system installed in North America. With FDMA, each channel can be assigned to only one user at a time. The D-AMPS also uses FDMA but adds TDMA to get three channels for each FDMA channel, tripling the number of calls that can be handled on a channel. It is also applicable in fixed networks.

Fibre Channel
High speed fibre-optic network system intended to support transmission speeds of up to 10Gbits/s plus.

Fibre Optics
Flexible glass or plastic rods that use light to transmit audio, video and data signals. Particularly suitable for digital communications as information is transferred by modulating the transmitted light. Has both a much higher transmission speed and capacity than copper wire or cable and is not subject to interference or noise. Fibre optics permit fast and high quality two-way, full-motion video and two-way audio interaction between participating sites, in addition to simple data transmissions. Bandwidth capacity of fibre-optic cable is much greater than that of copper wire.

Fixed-Line Network
Basic telephone network comprising subscriber lines, exchanges and inter-exchange lines. See PSTN.

Freedom of Mobile Multimedia Access (FOMA)
NTT DoCoMo's brand name for 3G services, based on the W-CDMA format.

Frequency
Number of complete cycles per unit of time, denoted by Hertz (Hz). 1 Hz = 1 cycle per second.

Frequency Band
Portion of the electromagnetic spectrum within a specified upper and lower frequency limit.

Frequency Band Allocation
Frequency band that is allocated to a service provider on which it is licensed to conduct business.

Frequency Modulation (FM)
Use of various frequencies to convey an analogue or digital signal. With frequency modulation, the frequency of the carrier is varied according to the amplitude of the transmitted signal. FM radio is an example of frequency modulation. AM varies the amplitude of the signal while FM varies the frequency. See also VHF.

Frequency Spectrum
Spectrum available for communication. Regulatory agencies monitor the occupancy of the radio spectrum and allocate to individual/group users, enabling a large number of services to operate within specific limits of interference.

Generation
As in 'third generation'. Refers to the type of technology used in a particular mobile phone network. Analogue was first generation, digital was second and UMTS is the third.

Global System for Mobile (GSM)
GSM is the de facto wireless telephone standard in Europe. GSM is based on TDMA and is the most widely used of the three digital wireless telephone technologies (TDMA, GSM, and CDMA). Digital systems offer higher transmission rates, low noise, improved security, international roaming capabilities and better spectrum utilisation relative to an analogue system. Also known as 2G. See also FDMA.

GPRS (General Packet Radio Services)
GPRS is one of three technology upgrade options for GSM networks, along with HSCSD and EDGE. It is a packet-based wireless communication service which promises data rates from 8.8 up to 114 Kbps and continuous connection to the Internet for mobile phone and computer users. GPRS is based on GSM communication and will complement existing services such as circuit-switched cellular phone connections and SMS.

Ground Station
Collection of communications equipment designed to receive signals from (and usually transmit signals to) satellites.

Hertz (Hz)
Unit of frequency equal to one cycle per second.

High Speed
Refers to data communications systems operating at speeds above 100Kps.

HSCSD (High Speed Circuit Switched Data)
HSCSD (High Speed Circuit Switched Data) One of three technology developments along with EDGE and GPRS which provides an upgrade of the GSM networks to improve their data capability. HSCSD increases speed sufficiently for the very basic video transmission and Internet access at rates close to existing fixed line rates. HSCSD did not become commercially available until 2000.

HTML (hypertext markup language)
The standard text language for documents on the word wide web.

i-Mode
i-Mode is the packet-based service for mobile phones offered by Japan's leader in wireless technology, NTT DoCoMo. Unlike most of the key players in the wireless arena, i-Mode ignored WAP and uses a simplified version of HTML, Compact Wireless Markup Language (CWML) instead of WAP's WML. NTT DoCoMo has said that eventually it will support WAP and WML, but the company has not indicated exactly when this will happen. First introduced in 1999, I-Mode was the world's first smart phone for Web browsing.

Integrated Services Digital Network (ISDN)
International standard which enables high speed simultaneous transmission of voice and/or data over an existing PSTN. Provides end-to-end digital connection for multiplexed communication channels. The most common ISDN system provides one data and two voice channels over a traditional copper wire pair, but can represent as many as 30 channels.

Integrated Voice Data
Typically refers to a workstation or a combination telephone/personal desktop computer which can combine voice and data signals over a single communications channel. That channel may be carried digitally on one pair of wires. See ISDN.

Internet
The global network of networks. It uses IP to link the various physical networks into a single network.

Internet Protocol (IP)
Internet Protocol (IP) Communications standard that defines the unit of information passed between systems and provides a basis packet delivery service for the Internet.

Internet Telephony
Method of carrying telephone traffic from one point to another through the Internet network using a packet switching system. Allows low cost international calling, costing the caller little more than a local call, though the quality of the call may often be poor.

Intranet
Closed data network (non-public) linking a number of sites. Could be regarded as an 'internal Internet'.

ISP (Internet Service Provider)
Company that provides individuals and other companies access to the Internet.

Latency
Time interval between the instant at which a network station seeks access to a transmission channel and the instant at which access is granted or received.

Liberalisation
Opening up a country's telecoms market to competition. Pan-European telecom liberalization occurred for most European countries on 1 January 1998.

Licensing
Administrative procedure for selecting operators and awarding franchises for the operation of particular telecoms services, eg mobile licences.

Line of Sight
Unobstructed path between antennas. Essential for very high frequency WLL to operate.

Location-based/ location-enabled services (also known as mobile positioning)
The ability to pinpoint the location of a mobile caller or vehicle in transit. These location-based services (LBS) are used for emergency purposes as well as enhanced business applications such as location sensitive billing, traffic updates, fleet management and asset and people tracking.

Megahertz (MHz)
One million radio waves, or cycles per second. Equal to one thousand Kilohertz.

Microcell
Interior mobile antennas with limited coverage ranges.

Microwave
High capacity radio waves used for point-to-point and multi-directional communication of audio, data and video signals. Microwave frequencies require direct line of sight between sending and receiving station to operate.

MIN (Mobile identification number)
Uniquely identifies a mobile unit in a wireless carrier's network, and can be used to dial from another network or fixed line and can be electronically checked to help prevent fraud.

Mobile Communications
Wireless form of communication through which signals are transmitted and received via microwaves. This type of communication allows customers to talk on a line and/or send and receive data signals while moving around from place to place. The signals are automatically bounced between base stations to the closest one as the customer moves around.

Mobile Telephone Exchange
Switching centre that manages calls in a cellular telephone system.

Modem
Device which enables data to be exchanged by interpreting and converting signals. A modem can convert a digital signal to an analogue signal, allowing computers to transmit and receive data, such as analogue Voice signals, over conventional telephone lines. Modems work in pairs, so at the other end of the channel the signal is returned to digital form.

Multimedia Messaging Service (MMS)
Electronic message service where the messages can comprise a combination of text, sounds, images and video. Only available on MMS capable handsets.

MVNO (Mobile Virtual Network Operator)
Mobile resellers that do not own networks but rather purchase wholesale minutes from one of the national incumbent mobile operators.

Narrowband
Term used to describe communications services or equipment that operate over a relatively narrow bandwidth. The PSTN is normally a narrowband network. Communications channels of less than 2Mbps (usually c56Kbps) are usually considered to be narrowband. See also Broadband.

Network Architecture
Set of design principles defining the protocol, functions and logical components of a network and how they should perform.

Network Operator
Licensed operator of a telecommunications network.

Number Portability
Ability of a customer to transfer from one operator to another and retain the original number. Also known as number mobility. Applies to both fixed and mobile.

OFTEL
UK regulator.

Packet
Unit of data that is routed between an origin and a destination on the Internet or any other packet-switched network. Each packet is separately numbered and includes the Internet address of the destination. The individual packets for a given file may travel different routes through the Internet. When they have all arrived, they are reassembled into the original file.

Packet Switching
Process of transmitting digital information by means of addressed packets so that a channel is occupied only during transmission of the packet. In contrast, data sent using circuit switching net modems occupies a circuit for the entire duration of transmission, even when no data is actually travelling over lines. Using packet switching, various packets of information can travel along different routes on the network, allowing the carrier to optimise network capacity.

Paired Spectrum
See Unpaired Spectrum.

Peak
Period when the telecoms operator charges customers the highest tariff to make a call, since this is the busiest time in terms of traffic carried. This is usually during the middle of the day, as opposed to Off Peak which usually includes the evenings and weekends.

Perigee
Point in a satellite's orbit that is closest to the earth.

Personal Communications Network/System (PCN/PCS)
Generic term used to describe the digital cellular service that is based on existing GSM and ISDN Standards. It is intended to be a mass-market service to rival PSTN. PCN/PCS operates at 1800MHz (and above) that is higher than analogue frequencies, so achieving greater capacity potential.

Point of Presence (PoP)
City or other location where the phone company network can connect to other networks or services. PoPs increase as a company rolls out its network increasing service availability.

Portability
See Number Portablilty.

Protocol
Format or set of rules and conventions that control the format and relative timing of message transmission between two points on a telecom connection or a computer network.

Public Switched Telephone Network (PSTN)
Infrastructure providing a country's telephone system. It is the means by which household and business phones are connected, typically by conventional fixed cables.

Pulse
Variation in electrical energy above or below a normal level and a given duration, such as a brief surge of voltage or current.

Real Time
Transmission or data processing operational mode in which the data is entered in an interactive (two way communication) session. Such applications are fast enough to affect later data input. Used in the streaming of video and audio applications.

Remote Access
Sending and receiving data to and from a computer through communications links such as phone lines.

Roaming
Describes mobile cellular telephone use which involves passing from the local service area of one company to that of another with a compatible network technology. This can also be done at the international level. Within your home network, this means that your mobile phone automatically sets up communication procedures with different radio base stations when on the move.

Signal
Induced change in state along a given channel.

Signalling
Act of sending messages between network switches and/or control points that convey information about circuit status, traffic loads, call routing and other immediate aspects of network operations.

SIM (Subscriber Identity Module) Card
Chip which authenticates the user's GSM mobile phone and allows calls to be made. Stores the user's personal profile and other information. Without the SIM card, calls cannot be made.

Smart Antenna
Antenna system whose technology enables it to focus its beam on a desired signal to reduce interference.

SMS (Short Messaging Service)
Electronic messages on a digital wireless network, allowing messages of up to 160 characters to be sent and received via the network operator's message centre.

Spectral Management
Management of the type and quantity of devices connected to the copper pairs to eliminate any interference between services on cable, and between those external radio services.

Spectrum
See Frequency Spectrum.

Spectrum Auction
When extra spectrum capacity becomes available it is usually sold via an auction process.

Telco
Local or regional telephone company that owns and operates lines to customer locations.

Telecoms
The transmission and reception of voice, data or other signals through electrical impulses. Includes all aspects of transmitting information.

Telephony
Area of telecommunications which deals with the transmission and reception of speech.

Third-Generation
See UMTS.

Throughput
Capacity of a network.

Time Division Multiple Access (TDMA)
2G technology developed in the US. Divides each cellular channel into three (GSM has eight) time slots in order to increase the amount of data that can be carried. Each user making a call is allocated a particular time slot, which he occupies for the duration of the call. TDMA-based cellular systems include European GSM, Japanese PDC and North American D-AMPS. However, each of these systems implements TDMA in a different and incompatible way. (See also CDMA and FDMA.)

Topology
Geometric or physical configuration of a network.

Traffic
Calls or other transmissions being sent and received over a communications network.

Transmission Control Protocol (TCP)
Transport protocol used on the Internet and the ethernet that allows packet transfer of data.

Transmitter Power Output Rating
Signal transmission power of telecoms equipment.

Transponder
Device in an orbiting communications satellite that receives a signal from earth, translates and amplifies the signal, and retransmits it back to earth.

Tri-band
Term applying to cellular handset/phone that will work on 800MHz analogue, 800MHz digital and 1900MHz frequencies. A tri-band cellular phone will operate on three different frequencies, depending on the available network. Outside America, the GSM frequencies used are 900MHz and 1800MHz. 'American GSM', or PCS, operates at 1900MHz. The introduction of tri-band phones is a further step towards true worldwide roaming.

UHF (Ultra high frequency)
Referring to radio channels in the 300MHz to 3GHz band.

Ultra Wideband (UWB)
UWB stands for Ultra Wideband, a new kind of wireless broadband which emits radio waves over a broad spectrum, risking the disturbance of other data traffic.

Universal Mobile Telecommunications System (UMTS)
A so-called 'third-generation (3G)' broadband, packet-based transmission of text, digitised voice, video, and multimedia at data rates up to and possibly higher than 2Mbps. See also GSM, GPRS, CDMA, TDMA.

Unpaired Spectrum
Used for one-way traffic to reflect the asymmetrical nature of some multimedia services. For example, an e-mail with a video clip is an asymmetric multimedia application - you only download data. This is different from Paired Spectrum which is used for the purpose of two-way communication, ie video-conferencing is symmetric - there is a continuous stream of information to and from the handset.

User Identity Module (UIM)
SIM card equivalent planned for W-CDMA handsets.

User Network Interface
Interface defined as a set of protocols and traffic characteristics, between the user and the ATM network (ATM switch).

Value Added Network (VAN)
Communications network that provides features such as message switching and protocol handling.

Value Added Services (VAS)
Services other than the standard voice communication facility offered by the telco. These include voicemail, caller line identification and call waiting. Requires a digital network.

VDSL (Very high data rate Digital Subscriber Line)
Developing technology that promises much higher data rates over relatively short distances (between 51 and 55 Mbps over lines up to 1,000 feet or 300 meters in length). It is envisioned that VDSL may emerge after ADSL is widely deployed and co-exist with it. A number of standards organisations are working on it.

Very High Frequency (VHF)
Lowest band of frequencies in the electromagnetic spectrum that can be used for the carriage of TV signals, due to bandwidth requirements. Also known as FM (Frequency Modulation).

Voice Frequency (VF)
Any of the frequencies in the band 300-3, 400Hz which must be transmitted to reproduce the voice with a reasonable degree of clarity.

Voice Grade (VG)
Access line suitable for voice. Generally, it has a narrowband frequency range of about 300-3000Hz. A low-capacity communications circuit/path. It usually implies a speed of 56Kbps or less. (Contrast with wideband and broadband.)

W-CDMA (Wideband code division multiple access)
Third generation standard developed and supported by GSM proponents. The natural upgrade from GSM and Japanese PDC. See also CDMA, FDMA, TDMA, UMTS.

WAP (Wireless Application Protocol)
Technology which allows mobiles to browse the web. It is a protocol for the transmission of data over low bandwidth wireless networks. The gateway connects phones to the Internet, while the micro-browser uses an XML document format called VML to display pages.

Wave Division Multiplexing (WDM)
Technology increasing fibre optic cable capacity by using several different light waves on a single fibre. See multiplexing.

Wideband
Term applied to facilities or circuits where bandwidths are greater than required for a single voice channel. Usually implies a speed from 64Kbps to 1.544Mbps.

Wideband Network
Capacity of a wideband network lies between that of a broadband network and that of a narrowband network. Services may include video teleconferencing, file transferring and video telephony.

WIN (Wireless intelligent network)
Architecture of the wireless switched network that allows carriers to provide enhanced and customised services for mobile telephones.

Wireless Communications
System that uses radio transmitters and receivers in place of wire lines which, when connected to the evolving public switched network (PSN), provides comprehensive telephone service to customers.

Wireless IP
Packet data protocol standard for sending wireless data over the Internet.

Wireless Local Loop (WLL)
Wireless connection of a telephone in a home or office to a fixed telephone network.

Wireless Markup Language (WML)
Language that allows the text portions of web pages to be presented on a mobile.

Zulu Time
Time designation used in satellite systems synonymous with Greenwich Meridian Time.

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