Within this channel, significant amounts of network-related information is passed to the mobile handset for its use. Length differences assist the mobile handset in monitoring control channels of surrounding cells while in a voice call, which brings us to the second channel combination. Data is encoded, interleaved, and formatted into four bursts with each being sent in one 26-slot multiframe. As can be seen, the airlink requires significant effort in terms of its management, which is generally handled by the L1 protocol. Synchronization As discussed earlier, burst timing within the allocated slot is critical for successful operation of TDMA systems.
Synchronization is a graceful approach to maintaining lock with the network timing standard.
Deviation from the network results from both an imperfect channel as well as diverse clock references. This is not good for mobile handsets using adjacent slots. To compensate for this clock difference, L1 estimates both signal timing and frequency error. Testing this operational feature requires adjusting the BTS timing, and then measuring the response on the mobile handset itself. The reception-time tracking speed is implicitly measured on the transmit bursts.