Noncoherent sequence detection of trellis coded CPFSK over Rician channels

In this study, noncoherent sequence detection of trellis coded continuous phase frequency shift keying (CPFSK) signals is considered over Rician fading channels with maximum ratio combining (MRC) diversity. A soft decision differential phase detector (SD-DPD) that chooses a differential phase subregion among a preselected set of subregions at the end of every interval is considered. The output of the SD-DPD is then used to calculate metrics for Viterbi decoding. Different trellis codes are analyzed over fading channels with different fading parameters, different numbers of diversity branches, and different numbers of differential phase subregions in the SD-DPD. Numerical results indicate that a suboptimal receiver that maintains the same set of metrics for all signal-to-noise ratios (SNR) performs close to optimal decoding.