A LDPC-Based Joint Source Channel Decoding Using HMM for Image Transmission System

A modified joint source channel decoding (JSCD) algorithm based on low-density parity-check (LDPC) coding and hidden Markov estimation is proposed to employ the self-checking mechanism of LDPC codes in adjusting the error probability p of the hidden Markov model (HMM) and the JSCD scheme utilizes the source residual redundancy while no priori information of the source parameters is available. We also extend and apply the algorithm over image transmission system. Simulation results show that the modified JSCD algorithm leads to the joint decoder converge at least 10% faster than the unmodified method without any degradation in the decoding performance. The method also obtains substantial improved performance in image quality of 3.0 dB-8.0 dB (PSNR) at 0.6 dB in E_b/N₀ when it is employed in still image transmission systems