Abstract

This thesis presents a novel iterative joint source and channel decoding scheme using turbo codes for MPEG-4 video transmission over noisy channels. The proposed scheme, on one hand, utilizes the channel soft outputs generated by a turbo decoder to assist syntax based error concealment in a source decoder. On the other hand, the residual redundancy extracted by the source decoder is fed back to the channel decoder through modifying the extrinsic information exchanged between the two constituent MAP decoders of the turbo decoder so as to improve the error performance of the turbo decoder. With video packet mixer, the proposed scheme can correct most of the turbo coding blocks with a large number of bit errors. Simulation results show significant improvement in terms of BER, PSNR and the reconstructed video quality.