Noncoherent demodulation techniques for trellis coded M-DPSKsignals

Considers noncoherent decoding of trellis coded M-DPSK transmission, and attempts to unify and contrast the approaches to this problem which have been previously reported. In the second part of the paper, the maximum likelihood block decoders for the AWGN channel are outlined, first assuming that the decoder has no knowledge of the state of the encoder at the beginning of the block, and then assuming that it knows the state. Because these exhaustive decoders suffer from an exponential growth in complexity with block length, two simplified decoders are proposed that approach the performance of the exhaustive decoders with a much more manageable complexity. Through a union bound analysis and computer simulations, it is shown that it is possible to achieve large gains over uncoded systems with a very reasonable decoder complexity