Network Congestion Control Based On Active Queue Management, A Number Of Issues

With the rapid development of Internet technology, people are more and more paying attention to the fatalness of severe congestion. The effective congestion control scheme is one of the key aspects of guaranteeing the stability of Internet. As one kind of supplement on the congestion control of the terminal systems, the Active Queue Management (AQM) algorithm acting on the intermediate nodes is able to control the queue length effectively on the basis of the high throughput of the routers. Therefore, the AQM algorithm can control the end-to-end delays for QoS guarantees, which made AQM become one of the hottest fields in the computer networks. This paper emphasized on designs of active queue management algorithms for Internet congestion control with control theory. The main research results are as follows:(1) In order to overcome the disadvantages of the traditional PID controller of the active queue management, e.g., fiercely fluctuation of queue length, and so on. We propose a new Active Queue Management algorithm based on separated integral PID algorithm and incomplete differential coefficient PID algorithm. Simulation results show that the new AQM algorithm has smaller queue fluctuation and overshooting number.(2) It is an arduous work of finding an active queue management scheme which is suitable for variational network condition. An output feedback controller (OFC) is proposed in this paper to solve the problem above, whose coefficient can be determined by the linear matrix inequality, via H_∞control of the linear time-delayed system. Finally, simulation results indicate that the proposed controller has a clear advantage in controlling network performance, which also has high robust stabilization under diverse network conditions.(3) We introduce a novel and robust active queue management algorithm based on rate and queue length, called NRaQ, which uses an adaptive neuron to tune its parameters. Simulation results show that the NRaQ algorithm has stronger robust performance and shorter regulating time than traditional PI algorithm.