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Shakeel Amin

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What is Wireless Communication..?

transmitting and receiving voice and data using

electromagnetic waves in open space. The information from sender to receiver is carried over by a

well defined frequency band (channel).

Each channel has a fixed frequency bandwidth and capacity

(bit-rate) Different channels can be used to transmit information in

parallel and independently.

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Example Assume a spectrum of 120 KHz is allocated over a base

frequency for communication between station A and

station B.

Each channel occupies 40 KHz.

STATION A

Channel 1 (b b+40)

STATION BChannel 2 (b+40 b+80)

Channel 3 (b+80 b+120)

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Cellular Networks: Generations First Generation (1G)

Launched in the mid 1980s.

Analog System. Analog Modulation. Mostly FM.

Voice traffic only.

FDMA multiple access.

Confined to national boundaries. Example: AMPS (Advanced Mobile Phone Services)

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Cellular Networks: Generations Second Generation (2G)

Global System for Mobile Communications (GSM)

FDMA/TDMA 900 MHz and 1800 MHz band.

Personal Digital Communication (PDC)

Popular in Japan.

IS-95

CDMA

US/South Korea

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Cellular Networks: Generations Limitation of Second Generation (2G)

Developed for voice communication.

(unsuitable for data traffic) Average rate of the order of tens of kbps.

Not suitable for internet (Packet Switched Services).

Multiple standards (no true global coverage).

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Cellular Networks: Generations 2.5 G

The effort to remove the impediments of 2G systems

resulted in 2.5 G.

Digital systems.

Voice + low data-rate.

Internet access through GPRS (General Packet Radio

Service). Enhanced data rate for Global evolution: uses better

modulation techniques.

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Cellular Networks: Generations 3G

Digital Modulation.

Simultaneous voice + high speed data. Multi-megabit internet access.

Voice activated calls.

Multimedia transmission.

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What is GSM..? GSM stands for global system for mobile communications.

GSM is a set of ETSI Standards specifying the

infrastructure for a digital cellular service.

The standard is used approximately in 85 countries

across the world including Europe, Japan, Australia,

and also in Pakistan.

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GSM (Global System for Mobile

Communications) 1991: First GSM network launched. DCS 1800

specifications finalized.

1992: Most European GSM networks turned commercial.

1994: Data transmission capabilities launched.

1995: About 156 members from 86 countries form the

network. 1996: 120 networks in 71 countries.

1997: 200 GSM networks in 109 countries.