Abstract: Continuous phase modulation (CPM) is an attractive technique for wireless communications due to its highly power and bandwidth efficiency, but the complexity of the CPM receiver increases exponentially with the modulation parameters. This paper proposes a noncoherent sequence estimation (NSE) algorithm which reduces the complexity of CPM demodulator remarkably. The front-end of the receiver is substituted by signal decomposition followed by vector multiplication, and the sequence decoding part of the back-end is truncated by the exponential window.