On Noncoherent FSK Reception With Doppler Frequency Uncertainty for Space Communications

This paper studies the mutual information for a general form of orthogonal M-ary frequency-shift keying (MFSK) modulations with non-coherent detection and Doppler frequency uncertainty at the receiver. The signal model includes as particular cases classical MFSK and special MFSK modulations, the later has been used in space communications for reporting spacecraft status and events during critical phases. The optimal code rates that minimize the energy-per-bit to noise power spectral density ratio required for reliable communications are studied. In addition, optimal and suboptimal metrics for soft-decoders are proposed for non-fading channels with or without average signal and noise power estimation and used to evaluate the performance of LDPC codes.