Relay Station Selection and Power Allocations for Multiple Description-Coded Video in Wireless Mesh Networks

Video transport in wireless mesh networks is a challenging problem because of frequent link failures, limited link capacity, and multihop communications. However, the mesh topology provides some degree of freedom in designing error resilient video broadcasting scheme, as multiple links can exist between a source and a destination. In this paper, we combine the mesh nature with Multiple Description Coding (MDC) technique to design a video broadcasting scheme. An Access Point (AP) is broadcasting video traffic to the Mobile Stations (MSs) via a number of Relay Stations (RSs). The AP utilizes MDC technique to encode video traffic into equal descriptions. Each description is multicasted to several RSs, which further broadcast the descriptions to MSs. Whether or not an MS can successfully receive a description from an RS depends on the transmission power of the RS and the channel conditions between the RS and the MS. For each MS, the quality of the received video depends on the total number of correctly received descriptions. We study how to allocate the transmission power of the RSs so that to satisfy the quality of the received video at each MS while minimizing the maximum transmission power at the RSs. An optimization problem is first formulated, and then a heuristic power adjustment scheme is proposed to find the transmission power of each RS. Our numerical results show a good match between optimal solution and proposed heuristic.