Performance optimization of partially coherent CPM on multipath fading channel

Constant Envelope, Continuous Phase Modulation (CPM) is highly desirable for low-power, battery-operated systems as well as for small-profile vehicular and aircraft systems where large amplifiers won't fit. In the past, CPM was noted for increased demodulator complexity (over simple PSK or FSK receivers) but with modern computational power it is possible to continue to improve the power efficiency of CPM modulation at the receiver. In the specific case of multipath, there are several known methods (Rake Receiver is one example) to resolve and correct for inter-symbol interference and phase distortion. This paper develops a standard CPM demodulation and compares the optimal coherent performance with a partially coherent receiver. Several methods are developed to compensate and correct for ISI due to various types of multipath and the power efficiency is compared to the original, coherent demodulation.