Low-Complexity Iterative Coherent Detection for Differentially Encoded MPSK

In this paper, a low-complexity power-efficient iterative detection scheme for differentially encoded MPSK transmission over AWGN and Rayleigh fading channels is presented. As the main contribution, a novel APP coherent demodulator, which well suits for iterative processing, is derived under the optimal bit-based MAP criterion. The implementation of iteration is not trellis-based, and needn’t reconstruct those transmitted symbols, but only independent coded bits are considered. We further provide performance comparison with other accepted soft demodulators, namely BCJR-type, MSDD, DF-DM and traditional differential detection, in terms of complexity analysis and Monte Carlo simulation. More practically, an image is also treated as information source and tested in the end. All results show that it is a right tradeoff, especially in the low SNR operation region.