Error restricted fast MAP decoding of VLC

Joint source channel techniques based on Variable-Length Coding (VLC) have been widely used. One of the most famous VLC decoders is optimal Maximum A Posteriori (MAP) decoder based on directed graph search and soft-input theory. Due to the high complexity of directed graph search, many reduced complexity methods have been proposed. In this paper, we propose two error restricted algorithms for fast MAP decoding of VLC and compare them with three existing methods. Simulation results show that our methods outperform existing methods in terms of decoding complexity with nearly the same performance on Symbol Error Rate (SER) of optimal decoding. When used in a larger codeword set, the superiority in decoding complexity of our methods is more remarkable.