Multiple trellis coded modulation using CPFSK signals

Multiple trellis-coded modulation schemes which combine two-state rate-2/4 multiple convolutional codes with CPFSK (continuous-phase frequency shift keying) modulation are considered. A computer search yielded such schemes with larger Euclidean free distances than previously considered rate-1/2 convolutionally encoded CPFSK modulation at the same bandwidth efficiency and demodulation complexity. Specifically, this search yielded schemes which were up to 3.5 dB more power efficient than the TCM schemes of G. Lindell et al. (1984) of the same bandwidth efficiency and decoding complexity