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G lobal S ystem for M obileC

A wireless mobile telecommunication Standard

In 1876 telephone was introduced to the publicin Philadelphia USA, ALEXANDER GRAHAM BELLwas a e o ransm speec e ec r ca y n onedirection only on COPPER WIRE. This was laterperfected for two way communication.

In the end of 19 th century a German Scientistnamed HEINRICH RUDOLPH HERTZ discovered

emanate invisible waves of force which could becaptured at a distant location by a suitableconstructed receiving device.

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In 1997 GUGLIELMO MARCONI made firstwireless transmission over 15KM in Bristolan in 1901 e transmitte t ese wavesoverseas and began to call it RADIO .

In 1982 first commercial ANALOG CELLULARSYSTEM was turned on in Chicago

In 1992, GSM the first fully DIGITAL

CELLULAR SYSTEM was introduced on inGermany and France

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The first generation cellular systems using analog voicetransmission came into operation in 1983 and were referred toas an analog technology

1G cellular systems use FM Modulation.

Example : AMPS (Advanced Mobile Phone Services)

1G wireless systems provide analog speech and inefficient, low-rate data transmission between the base station and the mobileuser.

1G cellular radio network includes Mobile terminals

The Base Stations MSC

Week security systems- results in hacking of telephone lines.Poor voice quality Poor battery life Largephone size No security, frequent call dropsLimited capacity and poor handoff reliabilitybetween cells

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Low power signal requires less battery.Digital voice encoding allows digital errorc ec ing w ic cou increase soun qua ity yreducing the noise.Going all digital resulted in the introduction of digital data services such as SMS.Using digital signals between headset and mobileincreases the capacity of the system

amount of radio bandwidthDigital voice data can be compressed andmultiplexed more effectively than analog voice.

Example of 2 nd Generation wireless systems include : GSM

GSM stands for Global System for Mobile Communication

Employ digital modulation and advanced call processingcapabilities, also have data services(GPRS, EDGE, SMS) formobile.

Use Digital Systems.

2 nd generation wireless networks have introduced newnetwork architectures and have reduced the computationalburden of MSC.

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GSM introduced the concept of BSC ( Base Stationcontroller), which is inserted between several

.

In second generation wireless networks, thehandoff is mobile-controlled and is known asMAHO (Mobile assisted Handoff).

Mobile networks in these networks performs

subscriber units, such as received power

reporting, adjacent base station scanning, dataencoding and encryption.

2 nd Generation telephone standard (DECT)allows each phone to communicate with anyof a number of base stations, byautomatically selecting the base station withthe greatest signal level.

2 nd Generation wireless networks have been

spec ca y es gne to prov e ata serv cessuch as high data rate network access.

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Third Generation wireless networks designed toincrease voice capacity and provide high-speeddata over 2G and 2.5G networks.A 3G network must provide a minimum of 144kbps.CDMA (Code Division Multiple Access) providesthe basis for 3G technology

CDMA assigns unique codes to each

communication to differentiate it from others inthe same spectrum