Algorithm of Low Complexity Viterbi Decoder in Convolutional Codes

Trellis of convolution codes has inherent symmetry and can be derived from generator sequences. By exploiting the inherent branch symmetry, the branch metric computation of the Viterbi decoder can be reduced significantly without any performance loss. Unfortunately, the butterfly structure only works for rate 1/n convolutional codes. Additionally, little is known in these studies. The study we present in the present paper is an attempt to supplement the findings of these earliest studies on the branch symmetry.