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Write a note on GSM Frame structure and its various bursts
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There are two types of multi frame:

1) 26 TDMA--frame of multiframe is used to carry TCH, SACCH and FACCH.

2) 50 TDMA--frame multiframe is used to carry BCCH, CCH, SDCCH AND SACCH.

Five types of bursts:

1. Normal Burst (NB):

. It is used to transmit both information and control bits

. T trail bits are used as guard time in achieving power level.-Training is used to estimate channel characteristics.

. SF stealing flags tells whether data or signalling is being transmitted.

. Normally for FACCH.

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Access Burst: . It is used to send the Random Access Channel (RACH) information - RACh contains the first message from MS to BTS.

. It has a long guard period to allow BTS to calculate the Ms distance from the BTS and to provide timing advance information to MS. enter image description here

3) Frequency Correction Burst (FCCH):

. It uses just to transmit Frequency Correction Channel (FCCH).

.142 bits are set to "0" in the known time slots.

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4) Synchronization Burst (SCH):

. It is used to transmit synchronization information

. The training sequence includes a well-known sequence of bits

. Alos contains the running number of TDMA frame.

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5) Dummy Burst:-

. It is transmitted when no other bursts are to be transmitted

. Uses same frequency channel which is used for BCCH to ensure if BCCH Transmits Burst in each time slot

. Quality monitoring

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