Rate allocation for multi-user video streaming over heterogenous access networks.

ABSTRACTContemporary wireless devices integrate multiple networking technologies, such as cellular, WiMax and IEEE 802.11a/b/g, as alternative means of accessing the Internet. Efficient utilization of available bandwidth over heterogeneous access networks is important, especially for media streaming applications with high data rates and stringent delay requirements. In this work we consider the problem of rate allocation among multiple video streaming sessions sharing multiple access networks. We develop and evaluate an analytical framework for optimal video rate allocation, based on observed available bit rate (ABR) and round trip time (RTT) over each access network, as well as the video distortion-rate (DR) characteristics. The rate allocation is formulated as a convex optimization problem that minimizes the sum of expected distortion of all video streams. We then present a distributed approximation of the optimization, which enables autonomous rate allocation at each device in a media- and network-aware fashion. Performance of the proposed allocation scheme is compared against robust rate control based on H∞ optimal control and two heuristic schemes employing TCP style additive-increase-multiplicative-decrease (AIMD) principles. Wesimulate in NS-2 [1] simultaneous streaming of multiple high-definition(HD) video streams over multiple access networks, using ABR and RTT traces collected on Ethernet, IEEE 802.11g, and IEEE 802.11b networks deployed in a corporate environment. In comparison with heuristic AIMD-based schemes, rate allocation from both the media-aware convex optimization scheme and H∞ optimal control benefit from proactive avoidance of network congestion, and can reduce the average packet loss ratio from 27% to below 2%, while improving the average received video quality by 3.3 - 4.5 dB in PSNR.