Distortion Control for Packet-Erasure Channels

We investigate the problem of finding minimum-distortion policies for streaming delay-sensitive but distortion-tolerant data over a packet-erasure channel. We consider cross-layer approaches which exploit the coupling between presentation and transport layers. We make the natural assumption that the distortion function is convex and decreasing, and we show that the optimum open-loop transmission policy is independent of the form of the distortion function. We then find a computationally efficient closed-loop heuristic policy which outperforms the open-loop policy and performs virtually as well as the optimum closed-loop policy.