On Active Queue Management Algorithms And Stabilities Based On Control Theory

The Internet protocol architecture is based on a connectionless end-to-end packet service using the IP protocols, and provides only best services. The most advantage of this mechanism is simple designing and strong expansibility, so Internet has gained flourish development since it appeared. In the past quite long time, TCP/IP protocols are all along the developing guarantee of Internet stabilization and exuberance, and are proved being maturity by the greatly richness and succeed of traditional network applications. But this superiority of TCP/IP protocols has cost, with the expanding of user numbers in Internet, the problem of network congestion is becoming more and more serious. Therefore, designing a simple and efficient congestion control algorithm becomes an urgently problem in network management. As an important module in high-speed router, active queue management (AQM) gets more and more recognitions in recent years. Implement of AQM sheme in high speed router is in order to provide small packet drops, high link utilization and low queue delay, which combines with TCP end-to-end c ongestion control being the main approach to solve the problem of Internet congestion control at present. Active queue management and transport control protocol (TCP) are all the while two active fields in communication group.The dissertation presents some active queue management algorithms based on intelligence control and robust control theories and makes further studys on the design of active queue management and stability analysis. The main research works and conclusions are as follows:The dissertation starts by presenting a fast responsive algorithm for AQM. In order to overcome the disadvantages of traditional PI controller, we applied fuzzy sliding mode control to network congestion control system, which does not need precise mathematics model. An AQM controller with both good steady-state response and transient response is obtained. By means of fuzzy control, the system performance is improved and the arriving time is reduced, at the same time, the high frequence jitter becomes smaller.