Blind per-state detection of DPSK over correlated fading channels

We consider a differentially encoded phase-shift keying (DPSK) signal transmitted over a channel affected by correlated Rayleigh fading. For this problem, we derive the exact maximum a posteriori (MAP) symbol detection algorithm. By analyzing its properties, we demonstrate that it can be implemented by a forward-backward estimator of the channel, followed by a symbol-by-symbol completion to produce the a posteriori probabilities of the information symbols. The resulting algorithm can be employed as a soft-input soft-output (SISO) block in turbo-iterative receivers and exhibits an excellent performance despite its limited computational complexity. The performance of the proposed algorithm is evaluated for time-domain modulations over frequency-flat channels and for frequency-domain modulations over time-invariant channels.