Theoretical Research Of Quality Of Service (QoS) In Computer Networks

With the technology improvement of computer communication and multimedia coding, real time communication such as audio and video is introduced to networks and become a dominant way of communication. But there are still quite a lot of problems; we call them "Quality of Serve" (QoS). How to provide QoS to computer communication networks is becoming more and more important to us.There're lots of research works for providing QoS, based on these works, we first focus on the QoS models defined by IETF, and analyze the characteristics of them. Since a single model always has drawbacks, so we usually combined these models in practical use.Following works are focused on the mechanisms of the network node, which is a very important part of this thesis. The word "node" we mentioned is considered as both the end node and the network router. As an end node, we provide the flow control and congestion control mechanisms based on TCP protocol, which is widely used. In network routers, we mainly provide some other mechanisms to guarantee QoS, including connection control, buffer management, traffic shaping, and congestion control. Finally, we work on the scheduling mechanisms for QoS-capable routers. Comparing with other references, the main difference is that we take most effort to the algorithms not the models, and verified the conclusions based on simulations. Furthermore, the coding method of simulation is so called "Event Scheduling", not the existing software; therefore, it's better for the detailed understanding of these algorithms, which is another difference with other references.Until now, QoS is still an open field for researching, and there're still many active topics to be discussed. In the end of each chapter, we bring forward the advanced work we'll be facing and hope QoS will have a bright way in computer communication networks.