We investigate the problem of finding minimum-distortion policies for streaming delay-sensitive but distortion-tolerant data. 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. We focus on a single source-destination pair and analytically find the optimum transmission policy when the transmission is done over an error-free channel. This optimum policy turns out to be independent of the exact form of the convex and decreasing distortion function. Then, for a packet-erasure channel, we analytically find the optimum open-loop transmission policy, which is also independent of the form of the convex distortion function. We then find computationally efficient closed-loop heuristic policies and show, through numerical evaluation, that they outperform the open-loop policy and have near optimal performance.

This work was supported in part by a subaward from the U.S. Army, prime award W911NF-05-1-0246. Prepared through collaborative participation in the Communications/nand Networks Consortium sponsored by the U.S. Army Research Laboratory under The Collaborative Technology Alliance Program, Cooperative Agreement DAAD19-01-2-0011.