Performance of a suboptimal noncoherent receiver for continuous-phase modulation

The optimal receiver for continuous-phase modulation (CPM) is a coherent maximum-likelihood sequence estimation (MLSE) receiver. If the phase of the transmitted signal is constant, a noncoherent MLSE receiver performs nearly as well as a coherent MLSE receiver. Phase variation over the course of a transmission, however, can seriously degrade the performance. Some and Kam (see IEEE Trans. Commun., vol.45, p.765-7, July 1997) have proposed a modification of the noncoherent MLSE receiver in which decision statistics are based on subsequences of the received sequence of demodulator outputs. In this paper, we present simulation results for this suboptimal noncoherent receiver for partial-response CPM and examine the sensitivity of the receiver to phase drift and timing offset. The results show that partial-response CPM with noncoherent reception can provide reliable, bandwidth-efficient communication in the presence of errors in symbol timing and carrier frequency