Diversity combining and Reed-Solomon coding for fast frequency hopped noncoherent MFSK

A robust concatenated coding scheme to provide protection against intelligent jamming is presented. The concatenated code uses a simple repetition (diversity) inner code and an outer Reed-Solomon (RS) error-correcting code. Two powerful diversity combining methods, normalized envelope detection (NED) and the second-and-first moment (2-1 M) method, are considered. The signaling is fast frequency hopped noncoherent M-ary frequency shift keying (FSK), which provides an inherent diversity. Ratio statistics from the combining operation are used to provide quality information on the received FSK symbols for erasure-correction RS decoding. A successive error-erasure decoding algorithm using this information is found to produce a bit error rate (BER) less than that using error-correction decoding alone. The improvement over diversity combining alone is significant when the RS decoder input BER is less than 10^-2