Time advance (alignment) process The RF communication experiences a propagation delay over the DISTANCE between the BTS and the MS. In order to synchronize the MS to the BTS, a timing advance is used to align the time slots ARRIVING at the BTS receiver:

1. The BTS measures the reception time of the incoming MS burst
2. The BTS requests the MS to advance its transmission to compensate for the delay over the distance. A 6-bit number indicates how many bits the MS MUST advance its transmission.
3. The time advance value TA can have a value between 0 and 63 bit lengths, which corresponds to a delay of between 0 and 233 ms.
4. This leads to a maximum mobile range of 35 km, which is rather determined by the TA than by the signal strength.

Time advance (alignment) process The RF communication experiences a propagation delay over the distance between the BTS and the MS. In order to synchronize the MS to the BTS, a timing advance is used to align the time slots arriving at the BTS receiver: