Adaptive Viterbi decoding of convolutional codes over memoryless channels

TLDR: An adaptive decoding algorithm for convolutional codes, which is a modification of the Viterbi algorithm (VA), which yields nearly the same error performance as the VA while requiring a substantially smaller average number of computations.

Abstract: In this paper, an adaptive decoding algorithm for convolutional codes, which is a modification of the Viterbi algorithm (VA) is presented For a given code, the proposed algorithm yields nearly the same error performance as the VA while requiring a substantially smaller average number of computations Unlike most of the other suboptimum algorithms, this algorithm is self-synchronizing If the transmitted path is discarded, the adaptive Viterbi algorithm (AVA) can recover the state corresponding to the transmitted path after a few trellis depths Using computer simulations over hard and soft 3-bit quantized additive white Gaussian noise channels, it is shown that codes with a constraint length K up to 11 can be used to improve the bit-error performance over the VA with K=7 while maintaining a similar average number of computations Although a small variability of the computational effort is present with our algorithm, this variability is exponentially distributed, leading to a modest size of the input buffer and, hence, a small probability of overflow