Low-complexity iterative detection techniques for slow-frequency-hop spread-spectrum communications with Reed-Solomon coding

Slow-frequency-hop (SFH) spread-spectrum communications provide a high level of robustness in packet-radio networks for both military and commercial applications. Reed-Solomon (R-S) coding has proven to be a good choice for countering the critical channel impairments of partial-band fading and partial-band interference in a SFH system. In particular, it is effective if information about the reliability of individual code-symbol decisions or the content of entire dwell intervals is obtained at the receiver and used in errors-and-erasures (EE) decoding of the R-S code words.; In this dissertation, we consider high-data-rate SFH communications for which the channel in each frequency slot is frequency selective, manifesting itself as intersymbol interference (ISI) at the receiver. The use of a packet-level iterative equalization-and-decoding technique is considered in conjunction with a SFH system employing R-S coding. In each packet-level iteration, MLSE equalization is used in each dwell interval and is followed by bounded-distance EE decoding of the R-S code words. Several per-dwell interleaver designs are considered for the SFH systems. It is shown that packet-level iterations result in a significant improvement in performance with only a modest increase in detection complexity for a variety of ISI channels. The use of differential encoding in conjunction with the SFH system and packet-level iterations is also considered, and it is shown to provide further improvements in performance with only a modest additional increase in detection complexity. The performance SFH systems employing packet-level iterations with and without differential encoding is also evaluated for channels with partial-band interference. Comparisons are made between the performance of this system and the performance of SFH systems using some other codes and iterative decoding techniques.