Performance of the FFH/BFSK self-normalized receiver with convolutional coding and soft decision decoding over Rician fading channels with partial-band noise interference

In this paper an error probability analysis of a communications link employing convolutional coding with soft decision Viterbi decoding implemented on a fast frequency-hopped, binary frequency-shift keying (FFH/BFSK) spread spectrum system is performed. The signal is transmitted through a Rician fading channel with both wideband thermal noise and partial-band noise interference. The receiver structure examined is the self-normalized combining receiver with diversity. The self-normalized receiver minimizes the effects of hostile partial-band interference, while diversity alleviates the effects of fading. We find that with the implementation of soft decision Viterbi decoding, the performance of the self-normalized receiver improves dramatically at moderate signal power-to-interference power ratios. Coding drives the jammer to a full band jamming strategy for worst case performance. Nearly worst case jamming occurs when barrage jamming is employed and there is no diversity except in cases where there is very strong direct signal. When the energy per bit and the total spread bandwidth is held constant, performance degrades slightly with increasing diversity except in instances of a very weak direct signal. When the spread bandwidth expands with increasing diversity, the jammer is forced to spread its power over a wider bandwidth and diversity offers some performance advantage.