Evaluation of block turbo code performance with the reduced search trellisdecoding method

Iterative decoding of parallel concatenated codes, also known as turbo code s, can provide tremendous coding gain approximating to the Shannon limit. A pplication of turbo coding techniques to block codes gives many advantages, due to the finite code length of the constituent codes and their ease of m odification. The authors investigate the application of the trellis decodin g method to block turbo codes, since one of the most easy and efficient way s of providing soft output at the decoder is incorporation of the trellis d ecoding method. The soft output Viterbi algorithm is mainly considered, wit h performance improvement techniques. The authors propose efficient reduced search algorithms in which the decoder complexity can be reduced about ten times with less than 0.1dB degradation in coding gain.