Optimum and suboptimum receivers for M-ary CPM signals based upon the Laurent representation

This paper involves a method for reduced complexity demodulation of continuous phase modulated (CPM) signals, which is based upon the extended Laurent representation of the nonlinear CPM modulation as a sum of time-offset pulse amplitude modulations. For signaling schemes with a long memory we derive a reduced complexity maximum-likelihood (ML) detector by approximating the CPM signal with a set of optimized pulses. The implementation is done for the non-binary case and for partial response CPM systems. It is demonstrated that, in the context of sequence detection, a remarkable receiver complexity reduction is possible using this method. The performance criteria used in the paper is symbol error probability and comparisons are made with other algorithms.