Active Queue Management Algorithm For The Delay Network

As one kind of supplement on the congestion control of the terminal systems, the Active Queue Management(AQM) argorithm 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 argorithm can control the end-to-end delays for QoS guarantees, which made AQM become one of the hottest fields in the computer networks.The impact on the performance caused by large delay always be neglected in the existed algorithms to the author's knowledge.A fact through simulation experiments is verified, which is the queues controlled by several typical AQM algorithms,including RED,REM,PI controller and PID controller; the dramatic oscillations in large delay networks are appeared, which decreases the utilization of the bottleneck link and leads to the unavoidable delay jitter. This paper concerns the influence on the performance of active queue management (AQM) in network caused by the time delays, and modeles the network from the control-theoretic point of view. Then the emphasis of research in the congestion control turns into the research investigation of the control algorithms and their preferences, where the control theory can work. At the same time, some strategies in time delay system are sumed up. The main concern of the paper is to rise a Smith-PI algorithm based on modified compensator and another modified Smith-PI algorithm based on Human Simulated Intelligent Control by the applying of Smith predictor and intelligence control. Finaly, a sets of simulation experiments are provided to demonstrate the effectiveness of the proposed algorithm. We can see that these two new algorithmes restrict the negative impact on the queue stability caused by the large delay and is obviously superior to that of the existed schemes.