Robust Transmission of H.264 Coded Video Using Three-Stage Iterative Joint Source and Channel Decoding

In this paper we considered jointly optimised source and channel decoding, while employing serially concatenated and iteratively decoded Short Block Codes (SBC) combined with a Unity Rate Code (URC) and multi-dimensional Sphere Packing (SP) modulation. The resultant coded signal is transmitted over non-coherently detected Multiple-Input Multiple-Output (MIMO) Differential Space-Time Spreading (DSTS) designed for near capacity joint source-channel decoding (JSCD). The performance of the system was evaluated by considering interactive video telephony using the H.264/AVC source codec. The source coded parameters generated by the state-of-the-art H.264/AVC video codec typically contain limited natural residual redundancy. Therefore, to improve the error robustness of iterative sourcechannel decoding (ISCD), SBCs are incorporated to impose artificial redundancy on the source coded parameters. The natural residual redundancy after source coding and the artificial redundancy due to SBC coding is iteratively exploited in a turbo process to improve the overall Bit Error Ratio (BER) and objective video quality performance quantified in terms of the Peak Signal to Noise Ratio (PSNR). The convergence behaviour of the advocated MIMO transceiver is investigated with the aid of Extrinsic Information Transfer (EXIT) charts. The proposed system exhibits an E_b/N₀ gain of about 22 dB at the PSNR degradation point of 2 dB in comparison to the benchmarker scheme carrying out DSTS aided SP-demodulation as well as iterative source and channel decoding, when using I_system = 5 system iterations, while communicating over correlated narrowband Rayleigh fading channels.