Non-Coherent Sequence Detection of QAM

Extended abstract In this paper we present a new non-coherent sequence detection algorithm for quadrature amplitude modulations (QAM) transmitted over additive white Gaussian noise (AWGN) channels. Our detection scheme is non-coherent in that it does not need any explicit carrier phase reference. Under the assumption of a constant channel phase model, it may easily be shown that the sampled output of a lter matched to the basic pulse of a linear modulation is a suucient statistics for optimal detection of the information sequence. This conclusion holds for both known and unknown stochastic phase models (see 1, appendix 4C] for the relevant background). For an unknown deterministic phase model, adopting joint maximum likelihood estimation of data and phase as a heuristic detection approach, this sampled output is still a suucient statistics (this conclusion turns out to hold even for other heuristic approaches). Assuming absence of inter-symbol interference (ISI), the samples fx k g at the output of