Master Thesis - 2009

Recently, video distributions using TCP have been increased rapidly with the improvement on the speed of access networks and capacity of the backbone network. They are called progressive downloads. Thus, it is an important technical issue to guarantee QoS(Quality of Service) of these video distributions. We have already proposed the output buffer control mechanism (QoSC : QoS Controller) in IP router to guarantee QoS per flow. This mechanism can provide the target bandwidth and target delay per flow by the combination of the packet scheduling and the packet discarding discipline.

However, to deploy QoSCs in video distribution networks, it still has several issues. Firstly, there are too many routers in the networks. Therefore, it is important to set the QoSCs at appropriate locations in video distribution networks because it is impossible to set the QoSCs at all routers. Secondly, there are too many flows in the networks. Therefore, it is important to select which video distribution flows are guaranteed in QoSCs because the available bandwidth is occupied to guarantee all of these flows.

Thus, proposed QoS management mechanism realizes sophisticated QoS guarantee in video distribution networks. Specifically, the QoSCs are set at access networks of both video distribution servers and users. The QoSCs on the video distribution server side guarantee flows which require strictly guaranteed bandwidth like streaming, while the QoSCs on the user side calculate and provide adequate transmission bandwidth according to network condition by measuring transmitted packets per flow in addition to guaranteeing these flows as well as the server side. In this way, the proposed control mechanism can guarantee more sophisticated QoS of video distribution. Though the evaluation in computer simulation, the effectiveness of our proposal was confirmed.