Performance simulation and analysis of M-ary frequency-shift keying with Reed Solomon encoding, coherent demodulation, and hybrid soft decision-hard decision decoding

All modern communication systems use some form of forward error correction coding. Generally, coding gain is improved when soft decision decoding is used instead of hard decision decoding. While soft decision decoding is a mature technology for convolutional codes, practical soft decision decoding for the commonly used Reed-Solomon (RS) non-binary block code has only recently been developed. Most of the developed SD decoding schemes are either applicable for low to medium code rates with high complexity or for channels that are far from q-ary symmetric. A hybrid hard decision-soft decision (HD/SD) decoding scheme was recently developed for use with bandwidth efficient modulation schemes such as M-ary phase-shift keying (MPSK). Since many communication systems use orthogonal modulation schemes such as M-ary frequency-shift keying (MFSK) for more robust communication links, this paper extends the HD/SD decoding scheme developed for bandwidth efficient modulation to orthogonal modulation. The performance simulation and analysis of MFSK with RS encoding, coherent demodulation, and hybrid HD/SD decoding are presented. The effect of noise other than additive white Gaussian noise, such as pulse-noise interference, is also considered. Furthermore, in our simulations we extend the size of the soft decision reliability information matrix from 2⁹ to 2¹⁰ in order to increase the possible decoding lists for hybrid HD/SD decoding.