多媒體網路串流的 P2P 及佇列管理技術之探討

Abstract

Many and various Internet applications are emerging with rapid development of communication technology and constant increase in user population. Currently, the Internet can only provide a best-effort service which does not fulfill the requirements of many new applications such as multimedia streaming. For this reason, researchers put their effort in studying this problem from many different aspects. In this Dissertation, we study the problem of multimedia streaming over Internet, and approach the problem from two layers—one from the application layer and the other from the network layer. For the application layer, we propose a scheme based on overlay network to meet the requirement of timely transmission by utilizing sampling/pre-fetching technique, as well as utilizing schemes developed by BitTorrent which is a popular peer-to-peer file sharing application. The design increases the exchange probability among participating peers in particular when these peers join at sparse points of time. For the network layer, we propose a queue management scheme for intermediate nodes, such as switches and routers, to improve the quality of communication in terms of end-to-end TCP performance, in particular loss rate, delay, and delay jitter. It takes the change rate of average queue occupancy into account and accordingly adjusts the behavior of handling incoming packets. By monitoring the change rate of averaged queue occupancy, the proposed scheme can early detect significant changes in traffic which may cause congestion. Both schemes are evaluated by simulations and compared with several existing schemes. Compared with a promising scheme previously proposed by Vlavianos et al., our application layer scheme can achieve up to 73% decrease in playback jitter under the condition of an initial latency of 80 seconds. The proposed scheme of queue management gains significant low packet delay, packet drop rate, and delay jitter even under different traffic types and network loads. At the cost of slight decrease in the utilization of links, we believe it can facilitate multimedia streaming over the Internet.