Low complexity decoding for convolutional codes

Several attempts to reduce the decoding complexity for convolutional codes are described. Although most of the attempts were unsuccessful, the author gained interesting insight which helped in understanding the theory of convolutional codes and led to further studies. It is concluded that the performance of the standard v=6 Viterbi decoder is hard to beat. The author gives a concatenated coding scheme using the same v=6 code and a distance 2 code to obtain an almost ML decoding algorithm with the performance of a d_free=20 code