SISO FB-MAP Detection for Turbo-Coded Differential PSK Systems

For turbo-coded differential phase-shift-keying (DPSK) systems under correlated flat-fading channels, a serial iterative structure of soft-input-soft-output (SISO) forward/backward MAP (FB-MAP) detection and SISO decoder is proposed to reduce the computational complexity of MAP detection without performance degradation. The simulation results show that the FB-MAP detection scheme offers the same or better bit error rate (BER) performance with lower computational complexity when compared with the a posteriori probability (APP) demodulator, the SISO MAP detection, and the SISO multiple-symbol differential sphere decoder (MSDSD) scheme. Although the computational complexity is higher than the iterative filtered multiple differential detection (IF-MDD) scheme, the proposed detection scheme can have better BER performance.