基于网络编码的P2P TV拓扑优化

Topology Optimization of Network Coding Based P2P TV

网络编码使得网络中间节点可以对收到的数据包进行特定的编码后再转发出去,以实现组播的最大吞吐率。这一技术应用于P2PTV系统,可以改善系统的有效传输率和延时等性能。为了缩短系统中节点等待数据包的时长和降低计算开销,实际系统大都对网络编码进行了简化。这使得数据包的冗余率受到拓扑结构的影响,增大了系统开销。针对这一问题量化分析了拓扑引起冗余的原因,提出了即时控制拓扑优化的方法,以对拓扑进行即时控制,优化拓扑结构。实验结果表明,相比已有工作,即时控制在数据包冗余率和节点上行带宽容量利用率之间取得了更好的折衷,并获得了更高的有效传输率。

With network coding（NC）,intermediate nodes can form outgoing packets through coding incoming packets to achieve the theoretically maximum throughput of multicast.Network coding has been applied in P2P TV systems to improve the performance of delivery ratio,delay and so on.Generally,it is simplified in existing P2P TV systems to shortenthe waiting time of nodes for incoming data packets and reduce computing overhead.This introduces the impact of the redundancy ratio of data packets on topology,and increases system overhead.The cause of redundancy brought by topology was quantitatively analyzed,and a topology optimization scheme named instant control was proposed to control and optimize topology spontaneously.Experimental results show that instant control reduces redundancy ratio of data packets caused by topology effectively.Compared with other similar work,it achieves better tradeoff between redundancyratio of data packets and utility ratio of uplink bandwidth capacity,and further reaches higher delivery ratio.