Analysis of frequency-hopping systems with combined convolutional and diversity encoding and non-ideal interleaving in worst case partial band jamming.

The interleaving span of coded frequency-hopping (FH) systems is often constrained to be smaller than the decoder memory length, i.e., nonideal interleaving is performed. An upper bound on the performance of a Viterbi decoder of a convolutional code with nonideal interleaving is presented. A soft-decision diversity-combining technique is introduced, and the performance of combined convolutional and diversity coding, subject to worst-case, partial-band noise-jamming, is investigated. The considered FH system uses M-ary frequency-shift keying (MFSK) modulation and noncoherent demodulation with two-bit soft-decision, based on A. J. Viterbi's ratio-threshold technique (1982).