Joint source and channel decoding of variable length codes based on pruned VLC-block trellis

Joint source and channel decoding (JSCD) of variable length codes (VLCs) has been attracting considerable attention in recent years. It is a capacity-approaching technique to decode in an iterative way, or known as iterative source-channel decoding (ISCD) of VLCs. When the side information of both bit length and symbol length of the VLC sequence are available, VLC-block trellis can be constructed, which exploits the knowledge of both lengths. The ISCD based on VLC-block trellis generally performs better than that based on the more widely used Balakirsky trellis. However, the complexity of VLC-block trellis is much higher, and grows exponentially with the sequence size. In this paper we study a sub-optimal solution by pruning some states and branches of the trellis. Simulation results show that this method can adjustably reduce complexity with acceptable performance loss.