MAP Frame Synchronization for PSAM Systems

Pilot symbol assisted modulation (PSAM) is a method to compensate for fading in wireless mobile communications. Known pilot symbols are periodically inserted into the data symbol stream and the receiver uses these symbols to derive the amplitude and phase reference required to set decision thresholds. In mobile communication, PSAM can facilitate the use of more bandwidth efficient modulation schemes. This paper focuses on frame synchronization to locate the time position of pilot symbols. We investigate a MAP estimation algorithm that assumes high SNR but also works well in moderate SNR. It retains good performance over a wide range of SNR in the AWGN and fading channels and frequency offsets as high as 10% of the symbol rate. The computed mean time to correct symbol timing decreases with increasing SNR and essentially reaches a minimum for any SNR greater than 6 dB. Also, the computational complexity of this MAP algorithm is almost as simple as the ML algorithm