Research Of AQM Based On Intelligent Control And Interrelated Problems In Congestion Control In Networks

Internet has been developed into the basic foundation of information society. With widespread use of networks as well as the appearance of varied network applications, Internet has been a heterogeneous network. However, the main kind of service is still "best effort" in Internet. Then congestion results in the decline of Quality of service (QoS) such as transmission delay and throughput, while the network resources utilization and buffers are also affected seriously. The success of Internet owes to the effective congestion control. The developing congestion control mechanisms are the critical factor in the operation and robustness of Internet. How to control congestion is one of the most active fields in the computer networks. QoS is one of the most active research areas within the networking field. Active queue management (AQM) aiming at the middle nodes is an important approach to resolve the congestion problem in IP network, while it guarantees QoS. Congestion control is the base of QoS. In the new architectures for different services, research on how to strength the congestion control to guarantee QoS is also the key.The paper researches the interrelated problems from the control-theoretic point of view. As the complicated networks, the work is challenging.The main contents and contributions are list below:(1) Analysis of the QoS guarantee system in the network and the different congestion control mechanisms; Focus on TCP end-to-end congestion control and the mechanisms implemented in IP routers; Compare the difference between mechanisms.(2) Modeling the network from the control-theoretic point of view, then the emphasis of research in the congestion control turns into research the control algorithms and their preferences.(3) Analysis of the AQM aiming at the middle nodes; Research the algorithms in AQM such as RED in the classical control theory; Intelligent control is powerful in the research of AQM. Synthesis of the fuzzy system, immune system and PID, a new FM-PID AQM is offered which can improve the robustness and response. To implement the FM-PID AQM is in Linux kernel infutrue.(4) Study of the QoS architectures suggested by IETF: IntServ/REVP, DiffServ and MPLS. Discuss the protocols, point out strengthen the congestion control mechanisms to support the QoS system.Finally, we make the conclusions and some future researches are proposed.