Video streaming over wireless networks is compelling for many applications, ranging from home entertainment to surveillance to search-and-rescue operations. When multiple video streams share a wireless network, careful rate allocation is needed to prevent congestion, as well as to balance the video qualities among the competing streams. In this dissertation, we present a distributed media-aware rate allocation protocol, and evaluate its performance in the application example of streaming high-definition (HD) and standard-definition (SD) video over 802.11-based wireless home networks.
Our optimization framework incorporates heterogeneity in wireless link speeds and video rate-distortion (RD) characteristics, as well as traffic contention among neighboring links. The goal of the protocol is to minimize the total video distortion of all participating streams while limiting network utilization. It relies on cross-layer information exchange between video rate controllers at the end hosts and link state monitors at the intermediate relay nodes. Results from various network simulations confirm that the media-aware allocation outperforms TCP-Friendly Rate Control (TFRC) in terms of average video quality and fairness among the streams.
The protocol is further extended for the scenario of application-layer video multicast over wireless. Following the same mechanism of congestion price updates at relaying wireless nodes and video rate updates at sending peers, the multicast extension of the protocol is designed to support either non-scalable or scalable video streams. As in unicast video streaming, the proposed media-aware protocol achieves lower average video distortion of all participating peers than a TFRC-based heuristic scheme.