The impact of inter-layer network coding on the relative performance of MRC/MDC WiFi media delivery
Proceedings of the 21st international workshop on Network and operating systems support for digital audio and video
Multicasting MDC videos to receivers with different screen resolution
ACM SIGMETRICS Performance Evaluation Review
On fair and optimal multi-source IP-multicast
Computer Networks: The International Journal of Computer and Telecommunications Networking
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A primary challenge in multi casting video in a wireless LAN to multiple clients is to deal with the client diversity--clients may have different channel characteristics and hence receive different numbers of transmissions from the AP. A promising approach to overcome this problem is to combine multi-resolution (layered) video coding with interlayer network coding. The fundamental challenge in such an approach is to determine the strategy of coding the packets across different layers that maximizes the number of decoded layers at all clients. This paper makes three contributions. (1) We first show that even for one client, the previously proposed canonical triangular scheme for inter-layer network coding can perform poorly. We show how to enhance the triangular scheme by incorporating the estimated target number of layers which significantly improves its effectiveness. (2) We show that such an enhanced triangular scheme still performs poorly for multiple clients with diverse channel characteristics, which motivates the need for searching for the optimal coding strategy. The naive way of searching for the optimal strategy is computationally prohibitive. We present several optimizations that drastically reduce the complexity of exhaustively searching for the optimal strategy, making it feasible in real time. (3) Finally, we design and evaluate an on line video delivery scheme, Percy, to be deployed at a proxy behind the AP of a wireless LAN. Our simulation results show that Percy outperforms the previous inter-layer coding heuristic by up to 22-80% with varying numbers of clients.