Optimum and suboptimum frame synchronization for pilot-symbol-assisted modulation

Pilot-symbol-assisted modulation (PSAM) is a method to reduce the effects of fading in mobile communications by periodically inserting known symbols in the data stream. The receiver uses these pilot symbols to derive its amplitude and phase reference. One aspect of this procedure which has not received much attention in the literature is the method used by the receiver to locate the pilot symbols. This paper uses optimum frame synchronization techniques to develop two synchronizers for PSAM systems; one is barred on a standard maximum likelihood (ML) estimation formulation, and the other is a sequential testing algorithm. Both methods use a simple quadratic correlation filter with an energy correction factor. Simulation results and a theoretical analysis are presented.