Cellular Telecommunications Glossary
- a glossary of terms used with cell phone or cellular telecommunications technology
This term refers to the first generation cellular systems that were based around analogue
technology. The voice channel typically used frequency modulation, and they used FDMA
This refers to a CDMA2000 operating mode which uses the basic chip rate of 1.2288 Mcps and a
channel bandwidth of 1.25 MHz. 1XRTT systems are often abbreviated to just 1X.
This term refers to the second forms of cellular telecommunications systems that were
introduced. The systems were digital and were oriented to voice with only low speed data
services. Systems such as GSM and US-TDMA used a mixture of TDMA and FDMA techniques.
IS-95 / cdmaOne was the first CDMA system.
The designation for systems following the 2G systems and they offer high speed data services in
addition to the basic voice capability. Typically they use CDMA techniques and include W-
CDMA, CDMA2000, and TD-SCDMA.
Third Generation Partnership Project.
The group that was set up to produce globally applicable Technical Specifications and Technical
Reports for a 3rd Generation Mobile System based on evolved GSM core networks. It produced
the standards for W-CDMA (UMTS). Later the scope of the organization was widened to include
the maintenance and development of the GSM Technical Specifications and Reports.
Third Generation Partnership Project 2.
The organization that is responsible for the specifications for the 3G developments for
The CDMA2000 operating mode at 3 times the basic chip rate of 1.2288 Mcps and having a
bandwidth three times that of the 1X system.
Modulation using Phase Shift Keying with 8 states allowing for coding using 8 bit combinations.
This allows for higher data rates to be sent than PSK systems using fewer states, although better
signal to noise ratios are required to ensure an acceptable bit error rate.
The standard for the link between the base transceiver station and the base-station controller.
Algebraic Code Excited Linear Prediction
A vocoder used in GSM and NA-TDMA.
Advanced Forward Link
Trilateration. A position location technique used on CDMA networks. It uses the measured time
of arrival of radio signals to the mobile from the base stations. Using this information the
network is able to determine the location of the mobile to an accuracy of around 200 metres.
A position location technique used for cellular telecommunications that is based around the
Global Positioning System (GPS). To provide a faster time to first fix and signal acquisition
under poor signal conditions, assistance data is provided by the network to the mobile.
Advanced Mobile Phone System.
The first generation analogue cellular system used in North America and many other countries
around the globe. It used a 30 kHz channel spacing, and FM was used to carry the voice channel.
Association of Radio Industries and Businesses.
The body responsible for telecommunications standards in Japan.
Average Revenue Per User.
The figure for the average revenue generated by each user on a mobile phone network.
It contains secure information about subscribers to a network including the permanent key of the
subscriber’s SIM card. This information enables it to provide authentication and encryption
parameters that verify the user's identity and ensure the confidentiality of each call protecting
users and network operators from fraud.
This refers to the handset or “phone?used on a CDMA2000 1xEV-DO network. It is called an
Access Terminal because EV-DO is a data only service.
Additive White Gaussian Noise.
An emulation of “white?noise often used in testing receiver sensitivity. It is also used for testing
CDMA systems because the noise simulates that which is generated by additional CDMA signals
on the same channel.
The signal or signals that are used to modulate the radio carrier in the transmitter, and in this way
the information can be carried by the radio signal. They may often be referred to as modulation.
The baseband signals are recovered by the receiver by demodulating the received radio signal.
Base Station Controller.
Mobile network component that contains all the logic used to control the operations of the BTS
and acts as an interface between the BTS and the MSC.
Base Transceiver Station.
The term for a mobile phone base station. A BTS contains the transmit and receive technology
and also the antennas to supply a cellular radio cell.
CDMA Development Group.
This is the consortium of companies that was formed to promote the adoption, development and
evolution of CDMA (i.e. cdmaOne and CDMA2000) wireless technology.
Code Division Multiple Access.
A cellular telecommunications access technology using direct sequence spread spectrum
techniques. By using DSSS it enables multiple users to gain access to a network by allocating
them different spreading codes.
This is a family of 3G cellular telephone standards. It includes CDMA2000 1X and beyond this
the CDMA2000 1xEv, evolution technologies that offer higher data rate services.
The first phase of CDMA2000 offering voice and data services. Peak data rates of 307 kbps can
be achieved using a single channel and when two are used this increases to 614 kbps.
The Evolution of CDMA2000 beyond 1X offering higher data rates. The two schemes that are
currently live or being developed are CDMA2000 1xEV-DO and CDMA2000 1xEV-DV.
This is the Data only or Data Optimized evolution for CDMA2000. As the name implies this
standard is optimized for data only and can offer data rates up to 2.45 Mbps under Release 0 of
the standard or 3.1 Mbps under Release A. It uses separate channels from the existing 1X
standard, and if voice traffic is to be handled an “Access Terminal?capable of using 1X must be
used and this is carried on a different channel to the data. The EV-DO standard is defined under
This is the Data and Voice evolution for CDMA2000. It supports both data and voice on the same
channel and data speeds of up to 3.1 Mbps can be achieved. The system is defined under IS-2000.
The first offering appears in Release C of the standard where the high data rate is only available
in the downlink, the uplink allows for data at the same rate as 1X. Release D allows for the high
speed data in both directions.
This is the brand name for the second-generation CDMA system defined under the IS-95
standard. It operates in the 800 MHz or 1.9 GHz radio frequency bands and uses 1.25 MHz-wide
Code Excited Linear Prediction.
A digital voice coding scheme that predicts the signal using past samples.
The European Conference of Postal and Telecommunications Administrations (Conférence
Européenne des Administrations des Postes et des Telecommunications).
It is the European telecommunications authority and it exclusively addresses sovereign/regulatory
matters for postal and telecommunications activities within Europe.
A single bit of a pseudo noise sequence.
The rate at which chips are sent. For CDMA networks where signals need to be spread over
bandwidths of 1 MHz and more chip rates are measured in millions of chips per second, Mcps.
This is the term for subscribers leaving one cell phone operator to go to another.
Circuit switched data
This is the technique that is used when a complete circuit is dedicated to a particular data
channel. The destination address is implicitly defined by the circuit that is selected. It offers a
simple solution to sending data over a channel, although it is not as efficient as packet switched
data because channel usage can be low and the channel cannot be shared.
A circuit used to convert analogue signals such as voice or video into a digital format for
transmission over digital medium. A receiver it also reconverts the signals to the original
analogue form. The circuit or algorithm used may also include compression and decompression
to reduce the level of data that needs to be transmitted. Codecs are widely used in mobile phones
and different coding algorithms used dependent upon the phone system used and the application.
Coded Orthogonal Frequency Division Multiplex.
A modulation scheme using a number of closely spaced orthogonal carriers. The data is spread
over these carriers and as a result it is resilient to multi-path and other forms of interference. It is
used for various forms of digital broadcasting and is being considered for the use with the fourth
generation cellular telecommunications systems.
This is a process that occurs when using spread spectrum techniques and it is the process of
synchronizing the phase of a local PN sequence within a radio receiver with that of the incoming
spread signal in order to “despread?and recover the narrowband data signal.
Cellular Telecommunications and Internet Association.
It offers many services including operating an equipment testing and certification program.
The transmission from cell phone base station to mobile phone or terminal. This term is normally
associated with GSM or UMTS networks.
Direct Sequence Spread Spectrum.
A modulation technique where a pseudo noise sequence is multiplied with data to be transmitted
and this sequence is used to phase modulate a carrier. The fact that the PN sequence has a higher
data rate than the data means that the bandwidth of the transmission is increased while the
spectral power density is lowered. The resulting RF signal has a noise-like spectrum, and in some
applications it can be intentionally made to look like noise to unauthorized listeners. To
regenerate the wanted data at the receiver the signal is “despread” by correlating it with a
pseudorandom sequence. This is identical to the one used during transmission and it must also be
in synchronization. Direct sequence spread spectrum is used as the basis of CDMA cellular
phones where different users are allocated different spreading codes.
A scheme where a mobile only transmits when the user is talking. This has the advantages that it
saves battery life and reduces interference levels, but it can clip the speech making it sound less
natural. During the quiet periods background noise has to be added at the receiver to give it a
more natural sound.
Enhanced Data rates for GSM Evolution (also referred to as Enhanced Data rates for Global
Evolution). The system utilizes the basic GSM / GPRS network, but uses 8PSK modulation
rather than GMSK to enable peak data rates of 384 kbps to be achieved.
Equipment Identity Register
The entity within a GSM system that stores information about the status of a mobile, for example
if it has been stolen.
Enhanced Observed Time Difference.
A location technology in which the mobile measures the time difference of the arrival of signals
from the base station. Using this information the network is able to calculate the position of the
This is a measure of traffic or load in a telecommunications system. 1 Erlang is equivalent to one
telephone line being permanently used.
An extension to the basic TACS system where further channels were allocated to create further
European Telecommunications Standards Institute.
The European Telecommunications Standards Institute that is responsible for telecommunications
Frequency division multiple access.
A technique that that enables multiple users to access a mobile phone network by allocating them
different frequencies or channels.
Frequency Division Duplex.
A technique to allow simultaneous transmission to and from the handset where the uplink and
downlink transmissions are separated by using different frequencies.
The transmission from the cell phone base station to the mobile phone or temrinal. This term is
normally associated with cdmaOne (IS-95) or CDMA2000 (IS-2000) networks.
Gaussian Minimum Shift Keying.
The form of phase shift keying used for GSM cell phone transmissions. It is a form of minimum
shift keying (MSK) that is passed through a filter with a Gaussian curve to reduce its bandwidth.
General Packet Radio Service.
An evolution of GSM system that uses packet data to provide a more efficient use of the available
data capacity and thereby enables maximum data speeds of up to 115 kbps to be achieved.
Global Positioning System.
A satellite based system for providing accurate position information. It uses the US DoD Navstar
satellites system consisting of a constellation of 24 active satellites that transmit signals that
enable receivers on earth to determine the position on the earth.
Global System for Mobile telecommunications.
A digital TDMA (2G) system developed in Europe and now widely used around the world.
A term used in the USA to describe the process of transferring a mobile from one cell to another
while it is in the middle of a call.
A term used in Europe to describe the process of transferring a mobile from one cell to another
while it is in the middle of a call.
A term normally associated with CDMA networks for a form of handover where the mobile has
to change channels, i.e. frequency to complete the handover.
Home Location Register.
A central database of permanent subscriber information for a mobile network. It is located on the
“home” network for the particular user.
High Speed Downlink Packet Access.
An enhancement to the W-CDMA standard which enables faster data rates (up to 14 Mbps) to be
achieved on the downlink from the Node B to the handset.
High Speed Uplink Packet Access.
An enhancement to the W-CDMA standard which enables faster data rates to be achieved on the
uplink from handset to the Node B.
International Mobile Equipment Identity.
A serial number contained within a mobile that is used by the network to check its status, i.e.
whether it is has been stolen.
International Mobile Subscriber Identity.
The number contained within the SIM card and used on the GSM system to identify a subscriber.
It relates the subscriber to the phone number.
International Mobile Telecommunications standard 2000 that defines the third generation mobile
The specification for the first cellular system to use CDMA techniques. Known under the brand
name cdmaOne there were two releases of the standard, namely IS-95A and IS-95B. The second
of B version is able to accommodate data at rates up to 115 kbps whereas the A version can only
accommodate speeds of 14.4 kbps.
The standard for the CDMA2000 3G cellular telecommunications system written by the TIA.
The International Telecommunications Union.
It is an international organization that is run under the auspices of the United Nations. Within the
organization governments and the private sector can work together to coordinate the operation of
telecommunication networks and services and advance the development of communications
technology. The ITU created the recommendations that defined the Third Generation (3G) mobile
Medium Access Control.
The networking protocol layer that is used to control transmission requests, authentication and
other overheads in local area network. It is widely used in cellular telecommunications (mobile
Mobile Internet Protocol
A scheme allowing users wither using computers connected to a "foreign network" whether by
wire or cellular phone to connect using a mobile IP address. In this way they are able to maintain
their connection even as they move from one base station and PDSN to the next.
Multimedia Messaging Service.
It is an extension of SMS. It has a much greater capacity allowing larger quantities of text as well
as attached images and audio files to be sent and as a result it is often referred to as picture
Mobile Switching Centre.
Interface between the base station system, i.e. the BTS and the switching subsystem of the mobile
Minimum Shift Keying.
This is a form of modulation where the phase changes are undertaken at the zero crossing points.
By adopting this technique the sidebands and hence the bandwidth required is reduced. It also
enables coherent techniques to be used to gain a 3 dB advantage. MSK signals are often filtered
to further reduce the bandwidth. One example of this is GMSK.
A cell system based on the AMPS analog mobile phone system but using a 10 kHz channel
spacing rather than 30 kHz. By adopting a narrower channel bandwidth spectrum efficiency
could be improved to cater for the increased usage, although voice quality was impaired.
North American Time Division Multiple Access.
A 2G digital cell phone system using TDMA techniques. It used a 30 kHz channel spacing to
provide compatibility with the frequency plans of AMPS. It was also known by names including
Digital AMPS (DAMPS) and US Digital Cellular (USDC).
Nordic Mobile Telephone.
An analogue (1G) cellular system that used either the 450 MHz or 900 MHz bands. It was
developed for deployment in Scandinavia, but its use spread to many other countries. It was the
first cellular system to be used commercially.
The name for what is effectively a base station for the W-CDMA / UMTS 3G cellular system.
Offset Quadrature Phase Shift Keying.
A form of quadrature phase shift keying where the quadrature (Q) component of the signal is
offset from the in-phase (I) component by half a symbol period. As a result the amplitude does
not cross zero, and this reduces the peak to average ratio. This has advantages for power
amplifiers because it reduces the peak to average ratio and as a result it is used in the reverse link
for CDMA transmissions.
This is a property of codes that can be used as spreading codes for direct sequence spread
spectrum (DSSS) transmissions. Codes are said to be orthogonal if they sum to zero over a period
of time. Orthogonal codes are used for DSSS transmissions because they do not interfere with
Packet Switched Data
Data transmitted from multiple users in individually addressed discrete packets. By using packet
data, channels can be used for transmissions from multiple users, thereby improving efficiency.
The channel used in GSM and CDMA that is used by the base station to transmit a message to a
mobile to indicate that there is an incoming message. The mobile monitors this channel while it
Pacific, or Personal Digital Cellular. The TDMA system based on NA-TDMA that is used
exclusively in Japan.
Position Determining Entity.
The area with in a cellular network that is used to determine the position of a mobile for
applications such as 911 calls. It will be associated with techniques such as A-GPS, AFLT, etc.
The channel used in CDMA for initial timing and BTS location.
Public Land Mobile Network.
The wire side of a communications network.
A binary sequence that exhibits random noise-like properties. PN codes or sequences can be
distinguished from random sequences because the pseudo-random sequence repeats after a given
time, i.e. it exhibits periodicity.
A protocol used to connect a computer to the Internet when using a standard dial-up telephone
line. PPP is also used when transmitting data in a cellular network.
Phase Shift Keying.
A form of modulation where the phase of the signal is altered to carry the information to be
Public Switched Telephone Network
The land line based or wired telephone system.
Qualcomm Code Excited Linear Prediction.
A voice encoder scheme that is used in CDMA systems and that was developed by Qualcomm.
Quadrature Phase Shift Keying.
It may also be known as quaternary or quadric-phase phase shift keying and it is a form of phase
shift keying modulation that has four states, usually at 0, 90, 180, and 270 degrees.
This is a technique used in digital signal processing where the radio receiver is given uses several
base-band correlators. The technique uses the fact that a signal will propagate via several paths to
a receiver. The signals arriving via different paths will reach the receiver at different times
because of the different path lengths. Using the Rake process all the components can be
individually processed and then combined to provide improved performance.
Radio Access Network.
The portion of a mobile phone network that relates to the transmission or radio communications
between the terminal device and the network base station.
Radio Access Technology.
The technology or system used for the cellular system. GSM and UMTS are two different radio
The path from the mobile handset or terminal to the base station. This term is normally associated
with cdmaOne (IS-95) and CDMA2000 (IS-2000) networks.
Radio Link Protocol.
A protocol used over the air interface.
Radio Transmission Technology.
The transmission technology used, in this context, by a cellular telecommunications system. It is
used particularly in the context of CDMA2000 where 1XRTT and 3XRTT are used.
Removable User Identity Module.
A card used in CDMA cell phones that stores the information to identify the caller to the
network. It is the equivalent of the SIM card used on GSM phones.
Subscriber Identity Module.
A card commonly used in GSM phones that store data that identifies the caller to the network
service provider. It also provides many other functions including the ability to store phone book
Short Message Service.
This is a system that enables short text messages of up to 160 characters to be sent and received
via the network operator's message centre. It is also possible to send messages from the Internet,
using a so-called "SMS gateway" website. It was first introduced on GSM.
A form of handover applicable to CDMA networks (including W-CDMA) where the mobile
changes its PN spreading code when handing over from one base station to the next while the
frequency channel remains the same.
A form of handover applicable to CDMA networks where the system hands over from one sector
of a base station to another using a different spreading code. As it is less complicated than soft
handover it is given the name, softer handover.
A method of transmitting a radio signal by spreading it over a wide range of frequencies. Direct
sequence spread spectrum (DSSS) in the form of CDMA is used as a cellular telecommunications
access technology. Another form of spread spectrum transmission is frequency hopping where
the signal moves from one frequency to another, remaining in one place for only a short time.
Total Access Communications System.
This was the first generation analogue system developed by Motorola that was used in the UK
and many other countries around the world.
Transmission Control Protocol / Internet Protocol.
This is a protocol that defines the way in which data is transmitted in a secure manner between
networks. It forms the basis for the Internet.
Time Division Duplex.
A scheme to allow (virtually) simultaneous transmission in both directions. The uplink and
downlink transmissions use the same frequency, but are allocated different time slots.
Time Division Multiple Access.
A system that that enables multiple users with access to a mobile phone network by allocating
them different time slots within a transmission. This scheme is used by GSM, NA-TDMA, and
Time Division Synchronous Code Division Multiple Access.
A 3G system that originates from China and uses TDD techniques.
Telecommunications Industry Association.
A US telecommunications standards body that was responsible for the generation of IS-2000, the
standard for the Third Generation CDMA system (CDMA2000).
Universal Mobile Telecommunications System.
The 3G follow on system to GSM that is standardized by ETSI under 3GPP. It uses Wideband
CDMA (W-CDMA) with a 5 MHz channel bandwidth.
The path from the mobile terminal to the base station. This term is normally associated with
GSM and UMTS networks.
Universal Subscriber Identity Module.
The subscriber identity module used in UMTS phones.
UMTS Terrestrial Radio Access Network.
The air interface (i.e. radio access) portion of UMTS networks as specified within 3GPP.
A family of orthogonal codes widely used for CDMA transmissions. They are one of a group of
specialized PN (pseudo-noise) codes that have good autocorrelation properties while exhibiting
low levels of cross-correlation.
Wireless Application Protocol.
It is a widely used set of protocols used on wireless devices such as mobile phones and PDAs. It
operates much like the hypertext transfer protocol and standardizes the manner in which wireless
devices are able to access parts of the Internet, such as e-mail and the Web.
The 3G transmission standard used for UMTS, the successor to GSM. It uses DSSS to provide
code vision multiple access with a bandwidth of 5 MHz.