Hybrid hard and soft decision decoding of Reed-Solomon codes for M-ARY frequency-shift keying

Abstract

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 and is currently limited to use with bandwidth efficient modulation schemes such as M-ary phase-shift keying. Since JTIDS/Link-16 uses quasi-orthogonal, cyclic code-shift keying (CCSK), in this thesis, soft decision decoding of RS encoded symbols is extended to M-ary frequency-shift keying, a power efficient modulation scheme. In addition, the soft decision decoding scheme recently developed, actually a hybrid hard decision-soft decision (HD SD) decoding scheme, is improved for both bandwidth efficient and power efficient modulation schemes. Finally, the effect of the hybrid HD SD decoding technique on signals corrupted by additive white Gaussian noise (AWGN) and other interference, including Pulse Noise Interference (PNI), is examined. The performances of various systems using the hybrid HD SD decoding technique were investigated using both analysis and simulation. It was found that HD SD decoding is generally effective in minimizing the degradation in system performance due to PNI but has only a small benefit when only AWGN is present.