Reduced-State Detection for Continuous Phase Modulation (CPM) Signals

It is known that continuous phase modulation (CPM) signals can be optimally detected by using maximum likelihood sequence estimation (MLSE) followed by viterbi decoding. However, such a receiver is generally complicated, particularly at higher numbers of states as it requires many correlators and many reference signals in the demodulator. So a much simpler receiver-reduced state sequence detector (RSSD) combined with decision feedback with viterbi decoding is studied in this paper. In this way, different tradeoffs between performance and complexity can be obtained. It is shown that, in a general case, a significant complexity reduction can be achieved, at the cost of a moderate degradation in performance.