Equalization and decoding in SFH spread-spectrum communications

There is an increasing need for tactical mobile radio networks that support link data rates of hundreds of kilobits per second to several megabits per second. If a radio network employing slow-frequency-hop (SFH) spread-spectrum modulation operates at these high data rates, however, the channel is likely to exhibit frequency-selective fading within each frequency slot of the SFH system. The frequency selectivity manifests itself as intersymbol interference at the receiver, and adaptive equalization must be employed in the receiver for each dwell interval in order to compensate for the intersymbol interference. We examine the performance of a SFH spread-spectrum system with Reed-Solomon coding in a channel that exhibits frequency-selective fading within each frequency slot. The performance is evaluated for a receiver that employs maximum likelihood sequence estimation in an equalizer that is retrained on a hop-by-hop basis. The use of parity bits for erasure generation is also investigated.