Global System For Mobile

Presentation on

Global system for mobile communication

Introduct ion • 1970 AT&T develop first US cellular telephone System called Advance mobile phone service(AMPS) • • In 1983 It deploy in urban and suburban area of chicago

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GSM is second generation cellular system standard that was develop to solve fragmentation problem Before GSM European countries used different cellular standard throughout the continent.

Frequency band & ARFCN qGSM used two 25MH cellular bands 1.890 – 915 MHz Uplink or Reverse channel 2.935 - 960 MHz Downlink or Forward channel qBoth bands are separated by 45 MHz qGSM used FDD and combination of TDMA and FDMA to provide multiple access to mobile user. qARFCN bandwidth is 200 kHz

q Number of ARFCN is 125 q q Each channel is time shared between eight user q Radio channel on both side uses GMSK Modulation. q Each frame duration is 4.615ms. q qEach timeslot duration is 576.92 µs

Cell Structure

Cell Area

Frequency Reuse, Sectoring and cell splitting

GSM Architecture HLR

MSC

VLR BSC AUC BTS

MS

MS

BTS

MS

MS

MS

Channel Type q There are mainly two type of channel 1.Traffic channel 2.control channel 3. qControl channel is again divided in three main type 1.Broadcast channel 2.Common control channel 3.Dedicated control channel

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