Non-coherent sequence detection of M-ary PSK

We present new non-coherent sequence detection algorithms for M-ary phase shift keying (M-PSK) signals transmitted over additive white Gaussian noise (AWGN) channels. We first consider the problem of optimal sequence detection in the presence of an unknown channel phase modeled as stochastic with uniform distribution and constant during the entire transmission. In this case, the complexity of the optimal receiver depends exponentially on the duration of the transmission. We then introduce some approximations in order to realize simple suboptimal detection schemes based on the Viterbi algorithm (VA) whose performance approaches that of coherent detection. Besides being realizable, the proposed suboptimal schemes have the convenient feature of allowing us to remove the assumption of constant phase during transmission. We show that our detection schemes compare favorably with other solutions previously proposed in the literature for both differentially and non-coherent coded modulations