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Lin X.-B.,Hefei University of Technology | Lin X.-B.,The Key Laboratory on High Performance Computing | Xu Y.-L.,Hefei University of Technology | Xu Y.-L.,The Key Laboratory on High Performance Computing | And 3 more authors.
Dianzi Yu Xinxi Xuebao/Journal of Electronics and Information Technology | Year: 2010

This paper focuses on layer rate allocation in network coding based layered media multicast. The sum of receiving rates of all receivers is maximized by optimizing layer rate allocation. Since it is a nonlinear integer programming, a heuristic algorithm, MRAA (M-layer Rate Allocation Algorithm), is proposed with the time complexity O(|V||T|2|E|2) to solve it. Algorithm MRAA decomposes the network graph into several subgraphs, and the minimum of the maximum flows of all receivers in each subgraph is the corresponding layer rate. Numerical results indicate that the algorithm MRAA can increase the network throughput by 15%-18% and improve the average bandwidth utilization rate of the receivers by 6%-10%, compared with the algorithm in the existing work.


Zhang C.,Hefei University of Technology | Zhang C.,The Key Laboratory on High Performance Computing | Hu Y.,Hefei University of Technology | Hu Y.,The Key Laboratory on High Performance Computing | And 4 more authors.
Journal of University of Science and Technology of China | Year: 2010

Under a saturated throughput model in 802.11 multi-rate WLANs, the ineffectiveness of rate adaptation on collisions and the impact of transmission probability on network performance were studied. Based on the relationship between the transmission probability and the value of contention window, an algorithm, which estimates the average number of consecutive idle slots to control contention window and decreases collisions to improve the performance of 802. 11 multi-rate WLANs was presented. Simulation results show that combining rate adaptation with contention window control can achieve much better network performances, including throughput and fairness, than only using rate adaptation in 802.11 multi-rate WLANs.

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