Exploiting multiple description coding for intermediate recovery in wireless mesh networks

Guarding against channel errors in wireless networks has been a challenging research problem, specially when transmitting time-constrained contents, like streaming video or image. Multiple Description Coding (MDC) has been designed for guarding against wireless channel errors. In MDC, a frame is broken into several equally important descriptions which can be sent over multiple paths to the destination. In this work, we leverage the routing scheme to exploit the path diversity in such a way that multiple descriptions are sent over different paths in the network and are merged at the intermediate nodes for possible recovery of corrupted descriptions. The routing uses the idea that when multiple descriptions join at intermediate points it can help in partial recovery of lost or corrupted descriptions by using the link error information, thereby improving the overall image quality at the destination. In order to achieve high gain in terms of peak signal-to-noise ratio (PSNR), we investigate an optimum spatial interleaving based MD coding scheme that maximizes the intermediate recovery possibility for a given recovery filter design. We also explore the choice of an optimum number of descriptions at an intermediate merging point that maximizes the PSNR gain. Our simulation study shows that it is possible to achieve a PSNR gain of around 5-6 dB using our coding and routing strategy.