Exploiting Redundancy in Iterative H.264 Joint Source and Channel Decoding For Robust Video Transmission

In this paper we propose joint optimisation of soft-bit assisted iterative joint source and channel decoding with the aid of our proposed EXIT chart optimised redundant source mapping (RSM) designed for guaranteed convergence to achieve an infinitesimally low bit error ratio (BER). Data-Partitioned (DP) H.264 source coded video is used to evaluate the performance of our system employing an iterative combination of RSM assisted soft-bit source decoding (SBSD) and recursive systematic convolution codes (RSC) for transmission over correlated narrowband Rayleigh fading channels. EXIT Charts were utilised to analyse the effect of redundancy using different RSM schemes on the attainable system performance, while keeping the overall bit-rate budget constant. Explicitly, our experimental results show that the proposed error protection scheme using RSM₂⁶ with d_H,min = 4 outperform the RSM₂³ scheme having d_H,min = 2 by about 5 dB, which in turn outperforms the RSM₅⁶ scheme having an identical d_H,min and overall system code-rate by about 2 dB at the PSNR degradation point of 2 dB. Additionally, an E_b/N₀ gain of 20 dB is attained using iterative soft-bit source and channel decoding with the aid of RSM₂³ relative to the identical-rate benchmarker.