what is timing advance in lte: -The eNB measures the required timing advance based on the received UE signal arrival time. It commands the UE to adjust the transmission time. This is performed on a per-need basis.

It is signaled by means of a special MAC control element; LCID = 11101.

The signaled granularity is 16 Ts.

The value range for adjustment is 8 bit and related to the current UL timing for time advance.

If the UE wishes to establish an RRC connection with the eNB, it sends a random access preamble, and the eNB estimates the transmission time of the terminal on that basis.

Now, the eNB sends a random access response consisting of a timing advance command based on the UE setting the transmission time of the terminal.

The time advance is initiated by E-UTRAN with a MAC message, which implies a time-out setting.

lte timing advance distance calculation:- As Ts. = 1 / (2048 x 15000) sec = 1 / 30720000 sec the granularity is given by 0.52 μsec (corresponding to 78 m means lte timing advance 78m)

If UE is in-sync the timing advance is valid. Otherwise the RACH-procedure establishes a valid timing advance. An 11 bit value (range 0,1..1282) is signaled to establish the initial offset.

The BASIC Behind TA (Timing Advance) is as per Below.

Timing advance in GSM :- For GSM A Timing Advance (TA) is used to compensate for the propagation delay as the signal travels between the Mobile Station (MS) and Base Transceiver Station (BTS).

The Base Station System (BSS) assigns the TA to the MS based on how far away it perceives the MS to be.

Determination of the TA is a normally a function of the Base Station Controller (BSC), bit this function can be handled anywhere in the BSS, depending on the manufacturer.

## Lte TA

TA is basical calculation of Path (Propagation Delay) Distance covered by Signal (Movement from Mobile to BTS ), It may be Direct Path or Indirect Path it value is 0 to 63 ,Default value is 63 It is Maximum Distance B/w MS and BTS , 1 TA value equal to 550m, i.e 0.5×63 =31.5km  we can restrict this Property by Dmax(BTS Parameter)