Symbol-aided plus decision-directed reception for PSK/TCMmodulation on shadowed mobile satellite fading channels

The symbol-aided (SA) synchronization concept developed by Moher and Lodge (1989) is applied to the MSAT channel modeled with a shadowed Rician process. Simulation data demonstrate that it can track the severe phase jitter encountered on the fading channel free of the false lock which plagues conventional techniques. The algorithm multiplexes known symbols into the data stream, establishing an absolute reference free of decision errors that is used to estimate the fading phase. An improvement to the SA algorithm which extracts phase information from the data-bearing symbols is proposed. It is found that the new technique is more effective for larger K. The improved algorithm is referred to as symbol-aided plus decision-directed (SADD) phase estimation. A system employing SADD phase estimation, trellis-coded modulation, interleaving, and amplitude weighting within the Viterbi decoder yielded the best BER performance on the shadowed MSAT channel considered