The time at which the phone is allowed to transmit a burst of traffic within a timeslot must be adjusted accordingly to prevent collisions with adjacent users.
This limit of 63 × 550 metres is the maximum 35 kilometres that a device can be from a base station and is the upper bound on cell placement distance.
A continually adjusted TA value avoids interference to and from other users in adjacent timeslots, thereby minimizing data loss and maintaining Mobile QoS (call quality-of-service).
Timing Advance is significant for privacy and communications security, as its combination with other variables can allow GSM localization to find the device's position and track the mobile phone user.
Until now the mobile station has used a timing advance to compensate for the propagation delay as the distance to the BTS changes.