NONCOHERENT CODED MODULATION

Trellis coded modulation with two or multidimensional signal constella tions, together with coherent maximum-likelihood detection, is conside red an attractive solution for communications over the additive white Gaussian noise (AWGN) channel. In this paper a new noncoherent communi cation system is introduced called noncoherent coded modulation (NCM) as an alternative to coherent coded modulation. NCM achieves almost th e same power efficiency, without bandwidth expansion or an extensive i ncrease in complexity. As a noncoherent system, the method does not ne ed carrier phase estimation. Nonetheless, differential encoding is not required. High performance noncoherent detection is achieved by using multiple symbol observations. Unlike previous approaches, a sliding w indow for the observations is used, with each observation covering sev eral branches of the trellis, such that the observations are time-over lapped. We define a new type of noncoherent maximum-likelihood sequenc e estimator (MLSE), and analyze its performance over the AWGN channel by numerical calculation of the union bound. We perform a computerized search and present new codes for noncoherent detection with their per formance. The new codes cover many useful rates and complexities and a chieve higher performance than existing codes for noncoherent detectio n. The method can also be used for multiple symbol demodulation of MDP SK with better results than existing methods.