Non-redundant error correction of uncoded M-DPSK using a modified Viterbi algorithm and a sliding block non-coherent multi-symbol detector

Abstract

Differential phase shift keying (DPSK) is often used in applications where system requirements make a phase-coherent reference at the receiver difficult to obtain or economically unattractive. Previous methods of reducing the energy penalty associated with the lack of phase coherence in DPSK using non-coherent detection have focused on non-redundant error correction (NEC) or sequence estimation techniques, optimal non-coherent (block) detection, trellis code modulation (TCM), and combinations of these methods. In the present paper, a new and general sub-optimal non-redundant error correction method for non-coherent detection of M-DPSK is proposed. The new method decides from 1 to N DPSK data symbols using a sliding block of N+1 phase measurements without adding any redundancy to the data signal using a technique derived from the Viterbi decoder for TCM. Simulation results for the additive white Gaussian noise environment show that while retaining the same general structure for different PSK signaling constellations, the new method achieves much of the performance of NEC and block detection without the exponential complexity in block length and TCM without any coding or increase in the signal constellation space. >