   # What is timing advance in GSM ?

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What is the aim of timing advance ? posted Feb 23, 2014
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## 1 Answer

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Timing Advance: -

The timing of the bursts transmissions is very important. Mobiles are at different distances
from the base stations. Their delay depends, consequently, on their distance. The aim of the
timing advance is that the signals coming from the different mobile stations arrive to the base
station at the right time. The base station measures the timing delay of the mobile stations. If
the bursts corresponding to a mobile station arrive too late and overlap with other bursts, the
base station tells, this mobile, to advance the transmission of its bursts.

1 TA = 554m.
Calculation is given below.
Timing Advance:

``````T × T (bit) = (2d) ⁄ c
Where T= Timing Advance
C = vel.of light 3×10^5 m /ms
T (bit) = 1 ⁄ 270.833
(Raw bit rate per carrier is 270.833 Kbps. Each carrier is shared by 8 users in TDMA Fashion.
There for bit rate for one user or one time slot is 1 / 270.833 Kbps ).
Now d = T ((T (bit) × c) ⁄ 2)
= T ((1 ⁄ 270.833) × 3 × 10^5) ⁄ 2)
Now after calc. d= T × 554 m
TA is from 0 to 63.
`````` answer Feb 24, 2014
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