Fast and robust timing synchronization for IEEE 802.16 MSs in mixed mode (16e, 16m)

Abstract

When the ABS supports mixed mode that is it supports both 16e MSs and 16m AMSs, if we have a Software Defined Radio which supports both 16e and 16m modes, then we can take advantage of the extra preamble available from the other mode to do either fast or robust coarse timing synchronization. For 16e mode, if the signal is weak and cannot synchronize on 16e preamble, the MS can first synchronize on 16m PA-Preamble and then offset back by a known integer number of 16e symbols to reach 16e preamble location. Usually for a given performance or bit error rate, the 16m PA-Preamble can work at 5dB SNR lower than the 16e preamble. Similarly when working in 16m mode, if the AMS wants to do fast synchronization and the signal quality is good, it can synchronize on 16e preamble first (which is available every frame as compared to 16m PA-Preamble which is only available every super frame) and then offset forward to 16m A-Preamble (PA-Preamble or SA-Preamble). This way we can make choices based on SNR level and time required to synchronize.