Iterative Multisymbol Noncoherent Reception of Coded CPFSK

Abstract—A multisymbol noncoherent receiver suitable for coded continuous-phase frequency-shift keying is developed and analyzed. Unlike coherently detected signals, the modulation index of the waveform does not need to be rational with a small denominator, and the oscillator only needs to be stable for the duration of a small group of symbols. The receiver is analyzed in terms of its symmetric information rate, demonstrating its potential when a capacity-approaching code is used and enabling the joint optimization of code rate and modulation index under a bandwidth constraint. The information-theoretic results are corroborated by bit-error-rate curves generated using a standardized turbo code in conjunction with iterative demodulation and decoding. It is shown that, while more robust than a system with coherent reception, the proposed system offers superior energy efficiency compared with conventional singlesymbol noncoherent reception. I