The BICM Capacity of Coherent Continuous-Phase Frequency Shift Keying

This paper presents a methodology for determining the capacity of coherently detected continuous- phase frequency shift keying (CPFSK) modulation under the constraints of binary coding and an ergodic channel. Building upon the capacity results, the coded CPFSK parameters of code rate, alphabet size, and modulation index are jointly optimized by using capacity as a cost function. From this optimization, it is possible to determine the minimum epsiv_b/No required for bit-interleaved coded CPFSK to achieve an arbitrarily low error rate as a function of spectral efficiency. Results showing this minimum epsiv_b/No are presented for a range of spectral efficiencies and several alphabet sizes in an AWGN channel.