Timing Advance/Network Measurement Report (TA/NMR)

This method relies in part on timing advance, which is the maximum amount of time that a TDMA mobile station uses to compensate for propagation delay in order to avoid user time slot overlap when the mobile is far away from the base station. It also employs information from the Network Management Report, which is the measurement done either at the handset or base stations to improve communication flow on the air interface. Various events – such as hand-off, power control, and candidates list – use the Network Management Report. Basically, the “timing advance” value is the length of time a signal from a mobile device takes to reach a particular base station. A TDMA frequency is shared between multiple users (employing TDMA) with each user transmitting periodically for less than 1/8 of the time within one of the eight timeslots. Since the users are various distances from the base station and radio waves travel at a finite speed (speed of light), the precise time at which the phone is allowed to transmit a burst of traffic within a timeslot must be adjust accordingly. Timing Advance (TA) is the variable controlling this adjustment.

Sources: Newton’s Telecom Dictionary 22nd edition 2006; http://en.wikipedia.org/wiki/Timing_advance