NONCOHERENT DEMODULATION TECHNIQUES FOR TRELLIS-CODED M-DPSK SIGNALS

We consider noncoherent decoding of trellis coded M-DPSK transmission, and attempt 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 blocklength, 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.