Suboptimum Detection of Bandwidth Efficient Partial Response CPM

A coherent CPM detector based on a reduced filter bank and a reduced state Viterbi decoder is proposed. Bit error probabilities of this detector for some CPM schemes satisfying a specific narrow spectrum requirement mask are simulated for the AWGN channel. The performance for one of the good candidates is then further evaluated for the case when co-channel and adjacent channel interference is present. For the AWGN channel with and without co-channel interference, the detector is found to be robust to complexity reduction both in the number of states in the Viterbi decoder and in the approximate filter bank. The number of states in the decoder and the complexity of the filter bank can be reduced significantly. It is still possible to reduce the complexity for the AWGN channel with adjacent channel interference, but not to the same extent without loosing significantly in performance.