Adaptive rate allocation scheme for joint source-channel coding based on double protograph LDPC codes

Although the joint source and channel coding (JSCC) system based on double protograph low-density parity-check (DP-LDPC) codes shows excellent error performance in wireless communications systems, there still is some space left for the improvement of error rate performance and the robustness of this JSCC system as it suffers high sensitivity to source statistics. In this paper, an adaptive rate allocation scheme under fixed bandwidth is presented for joint source-channel coding,which allocates rate adaptively between the source and channel codes according to channel state information and source statistics. The simulation results show that the proposed scheme can possess excellent error performance of both water-fall region at low signal to noise ratio (SNR) and error-floor region at high SNR. In addition, it is helpful to reduce the influence of source statistics to this system and improve the robustness.