Frequency Reuse
The ability to use the same frequencies repeatedly across a cellular system, made possible by the basic design approach for cellular. Since each cell is designed to use radio frequencies only within its boundaries, the same frequencies can be reused in other cells not far away without interference. The reuse of frequencies enables a cellular system to handle a huge number of calls with a limited number of channels.
GSM
GSM's air interface is based on narrowband TDMA technology, where available frequency bands are divided into time slots, with each user having access to one time slot at regular intervals. Narrow band TDMA allows eight simultaneous communications on a single radio multiplexer and is designed to support 16 half-rate channels. GSM also is the only technology that provides incoming and outgoing data services, such as email, fax, and internet surfing. GSM makes use of a SIM card that allows memory portability between 'dumb' GSM phones.
ETSI
European Telecommunications Standards Institute
ESN
Each cellular phone is assigned a unique Electronic Serial Number (ESN), which is automatically transmitted to the cellular base station every time a call is placed. The MTSO validates the ESN with each call.
EDGE
Enhanced Data rate for GSM Evolution.
Dual Band
Dual band phones are capable of using two different frequencies. For example, a TDMA or CDMA phone that can use either the 800 or 1900 MHz band. There are also Triple Band phones in the GSM market that support 900, 1800, and 1900 MHz. Dual band phones allow to access different frequencies in the same or different geographic regions, giving a wider coverage area.
Dual Mode
Dual mode phones that support more that one technology, e.g. CDMA and AMPS or TDMA and AMPS.
Control Channel
A channel used for transmission of digital control information from a base station to a cellular phone (forward control channel) or from a cellular phone to a base station (reverse control channel).
DSP
Digital Signal Processor, special-purpose microprocessor designed to handle signal-processing applications very quickly.
D-AMPS
Digital AMPS (see AMPS).
CODEC
Hardware in a phone and in the cell network that compresses digitized voice prior to transmission AND takes received compressed voice and decompresses it prior to passing it to either a cell phone speaker or into a wireline system. Codec allows the cell network to essentially pass a lot of data in compressed form to permit additional users on the system and to save bandwidth. The idea behind codec is that human voices are highly lossy and a significant amount of the conversation can be removed since human ears can fill in the removed gaps at the other end. Each technology has different codec algorithms -- for CDMA there is 13K and 8K.
Channel
A specific frequency, the communication medium. Also a point to point link in a connection oriented system.
Cell
The basic geographic unit of a cellular system and the basis for the generic industry term "cellular." A city is divided into small "cells", each of which is equipped with a low-powered radio transmitter/receiver or base station. The cells can vary in size depending on terrain and capacity demands. By controlling the transmission power and the radio frequencies assigned from one cell to another, a computer at the MTSO monitors the movement and transfers or hands off the phone call to another cell and another radio frequency as needed.
CDPD
Cellular Digital Packet Data, a protocol designed to be used over analog networks (AMPS). It allows voice and data transmission.
CDMAOne
Second generation of CDMA or IS-95B.
CDMA2000
Second generation of CDMA, also called 2G+, including 1XRTT and 1X EV.
CDMA
This protocol is also known as IS-95. CDMA differs from GSM and TDMA by its use of spread spectrum techniques for transmitting voice or data over the air. Rather than dividing the radio frequency spectrum into separate user channels by frequency slices or time slots, spread spectrum technology separates users by assigning them digital codes within the same broad spectrum. Advantages of CDMA include higher user capacity and immunity from interference by other signals. Available in either 800 or 1900 MHz frequencies.
Bluetooth
A wireless networking technology designed to replace cables that connect devices such as notebooks, handhelds and printers. The bluetooth specification provides for links between mobile computers, mobile phones and other portable handheld devices, and connectivity to the Internet. It enables users to connect a wide range of computing and telecommunications devices easily and simply without the need to buy, carry, or connect cables.
Bandwidth
A measure of communication channel capacity. The wider the bandwidth, greater the associated data rate.
AMPS
Advance Mobile Phone Service, an analog service. Available in U.S., Mexico, Canada, Australia and some other countries. It uses the 800MHz frequency band.
3G
Third generation of mobile service, digital. It offers a convergence of voice, data and multimedia content, at rates of up to 2mbps. The International Telecommunications Union (ITU) has laid down some indicative minimum requirements for the data speeds that the IMT-2000 standards must support. These requirements are defined according to the degree of mobility involved when the 3G call is being made. As such, the data rate that will available over 3G will depend upon the environment the call is being made in:
High Mobility: 144 kbps for rural outdoor mobile use. This data rate is available for environments in which the 3G user is traveling more than 120 kilometers per hour in outdoor environments. Let us hope that the 3G user is in a train and not driving along and trying to use their 3G terminal at such speeds.
Full Mobility: 384 kbps for pedestrian users traveling less than 120 kilometers per hour in urban outdoor environments.
Limited Mobility: At least 2 Mbps with low mobility (less than 10 kilometers per hour) in stationary indoor and short range outdoor environments These kinds of maximum data rates that are often talked about when illustrating the potential for 3G technology will only therefore be available in stationary indoor environments.
2.5G
Enhanced second generation of mobile service, digital. It offers data rates ranging from 28kbps to 384kpbs.
