Exit-Chart Aided Design of Iterative Joint Source and Channel Decoding for H.264 Video Technology
Nasruminallah, Lajos Hanzo · ePrints Soton (University of Southampton) · 2009
In this paper we propose a family of Short Block Codes (SBCs) designed for guaranteed convergence in soft-bit assisted iterative joint source and channel decoding, which facilitate improved iterative soft-bit source decoding (SBSD) and channel decoding.Data-Partitioned (DP) H.264 source coded video is used to evaluate the performance of our system using SBC assisted SBSD in conjunction with Recursive Systematic Convolution Codes (RSC) for transmission over correlated narrowband Rayleigh fading channels.The effect of different SBC schemes having diverse minimum Hamming distances (dH,min) and code rates on the attainable system performance is demonstrated, when using iterative SBSD and channel decoding, while keeping the overall bit-rate budget constant by appropriately partitioning the total available bit rate budget between the source and channel codecs to improve the overall BER performance and to enhance the objective video quality expressed in terms of Peak Signalto-Noise Ratio (PSNR) 1 .EXIT Charts were used for analysing the attainable system performance.Explicitly, our experimental results show that the proposed error protection scheme using rate-1 3 SBCs having dH,min = 6 outperforms the identical-rate SBCs having dH,min = 3 by about 2.25 dB at the P SN R degradation point of 1 dB.Additionally, an E b /N0 gain of 9 dB was achieved compared to the rate-5 6 SBC having dH,min = 2 and an identical overall code-rate.Furthermore, an E b /N0 gain of 25 dB is attained at the PSNR degradation point of 1 dB, while using iterative soft-bit source and channel decoding with the aid of rate-1 3 SBCs relative to the identical-rate benchmarker.I. MOTIVATION AND BACKGROUND Reliable transmission of multimedia source coded streams over diverse wireless communication networks, constitutes a challenging research topic [1,2].Since the early days of wireless video communications [3-6] substantial further advances have been made both in the field of proprietary and standardbased solutions [7,8].Furthermore, the joint optimisation of different functions such as joint source and channel decoding (JSCD) gained considerable attention.The family of JSCD schemes often relies on exploiting the residual redundancy in the source-coded bit-stream.Fingscheidt and Vary [9,10] proposed SBSD to exploit the natural residual redundancy of the source-coded bit-stream for improving the convergence of Iterative Source-Channel Decoding (ISCD) [11,12].However, only moderate residual redundancy is left in the source coded 1 PSNR is the most widely used and simple form of objective video quality measure, which represents the ratio of the peak to peak signal to the root mean squared noise [1].