An importance sampling analysis of a non-interleaved Viterbi decoder in an RFI environment

The authors present a model which analyzes a communications system consisting of a noisy channel, a transmitter/receiver, and a convolutional encoder/Viterbi decoder. The model determines the amount of bit error rate (BER) performance degradation caused by a bursty (e.g., pulsed RF interference) noise environment when interleaving is not used. It uses importance sampling to determine low BERs for a wide range of noise environments. It is faster than a conventional simulation because the required run time is independent of the BER. The model increases the simulation efficiency by biasing the burst error statistics so that more codeword errors occur and adjusts for this by using a weighting function whose value is calculated through the use of a Markov chain to represent the burst error statistics. The results confirm that interleaving results in a dramatic performance improvement in a bursty environment