Mobile Communication Generations 002

7/27/2019 Mobile Communication Generations 002

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M.P.Uditha IsurangaCommunicating Engineering InformationMEX3211


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What is Mobile Communication ? Mobile Communication Evolution

Before Cellular Networks

Way to 1st

Generation

1st Generation of Mobile Communications


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There are three common technologies usedby 2G cell-phone networks for transmittinginformation Frequency division multiple access (FDMA)

FDMA puts each call on a separate frequency.

FDMA separates the spectrum intodistinct voice channels by splitting itinto uniform chunks of bandwidth.


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Time division multiple access (TDMA) TDMA assigns each call a certain portion of time on a

designated frequency.

TDMA is the access method used bythe Electronics Industry Alliance andthe Telecommunications IndustryAssociation for Interim Standard 54(IS-54) and Interim Standard 136 (IS-136). Using TDMA, a narrow band that

is 30 kHz wide and 6.7 millisecondslong is split time-wise into three timeslots.


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Code division multiple Access (CDMA) CDMA gives a unique code to each call and spreads it

over the available frequencies.

CDMA takes an entirely different

approach from TDMA. CDMA, afterdigitizing data, spreads it out over theentire available bandwidth. Multiplecalls are overlaid on each other on thechannel, with each assigned a uniquesequence code


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GSM (Global System for Mobile Communications is a standardset developed by the European TelecommunicationsStandards Institute (ETSI) to describe technologies for secondgeneration (or "2G") digital cellular networks

GSM is a cellular network, which means that cell phonesconnect to it by searching for cells in the immediate vicinity.

GSM networks operate in a number of different carrierfrequency ranges, with most 2G GSM networks operating in

the 900 MHz or 1800 MHz bands


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GPRS General Packet Radio Service is a 2.5G network that

supports data packets. Data Up to 115kbps; theAT&T Wireless GPRS network will transmit data at

40kbps to 60kbps EDGE

Enhanced Data GSM Environment is a Similar to 3Gdigital network. May be temporary solution for

operators unable to get W-CDMA licenses. GPRS1networks evolved to EDGE networks with theintroduction of 8PSK encoding.


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The lower power emissions helped addresshealth concerns.

Going all-digital allowed for the introductionof digital data services, such as SMS andemail.

Greatly reduced fraud. With analog systems itwas possible to have two or more "cloned"

handsets that had the same phone number. Enhanced privacy.


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In less populous areas, the weaker digitalsignal may not be sufficient to reach a celltower

Sometimes Digital Signal may face to

dropouts While digital calls tend to be free of static and

background noise, the loose compressionused by the codecs takes a toll; the range of

sound that they convey is reduced 2G networks were built mainly for voice

services and slow data transmission.


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Mobile Communication Generations 002

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