Iterative two-dimensional error concealment for low-complexity wireless video uplink transmitters

Since joint source-channel decoding is capable of exploiting the residual redundancy in the encoded source signals for improving the attainable error resilience, it has attracted substantial attention. Motivated by the principle of exploiting the source redundancy at the receiver, in this treatise we study the application of iterative Error Concealment (EC) for low-complexity uplink video communications, where the video signal is modelled by a first-order Markov process. Firstly, we derive reduced-complexity formulas for the first-order Markov modelling aided source decoding. Then we propose a bit-based iterative EC algorithm, where a horizontal and a vertical source decoder are employed for exchanging their information using the iterative decoding philosophy. This scheme may be combined with low-complexity video codecs, provided that they retain some of the redundancy residing in the video signals and are capable of estimating the softbit information representing each bit of the video pixels. As application examples, we test our proposed two-dimensional iterative EC in both Wyner-Ziv video coded and uncompressed video transmission scenarios. Finally, we benchmark the attainable system performance against the existing first-order Markov process based softbit source decoding scheme, where the softbit decoding is performed by a one-dimensional Markov model aided decoder, as well as by the existing pixel-domain Wyner-Ziv video scheme. Our simulation results show that Eb/N0 improvements in excess of 6 dB are attainable by the proposed technique in uncompressed video home-networking applications. Furthermore, up to 21.5% bitrate reduction is achieved by employing our proposed iterative error concealment technique in a Wyner-Ziv video coding scheme.