Tcp Congestion Control, Active Queue Management Algorithm

Nowadays, with the rapid development of science and technology, we are very familiar with Internet. Almost all the industries depend much on the convenient service of Internet. However, there still exist a lot of problems in the real networks. One of the most common problems is that the respond speed is still too low. Thus, the congestion control of the Internet is alcey problem. The goals of Internet congestion control are maximization of throughput, minimization of the average delay of packets, fair allocation of resources among users, and minimization of packets dropped. Each of these has strong relationship with the quality of service. Therefore, the congestion control is an active reseach area of network.This thesis reviews the state of art in Active Queue Management (AQM), and the new AQM algorithms are proposed based on control theory. Simulation results are given to prove the performance of the new AQM algorithms. The contributions of this thesis are as follows:1. A new intelligent PID is proposed as active queue management (AQM) algorithm and realized in Network Simulator. The simulation results show that the performance of response time of the proposed algorithm in LAN is obviously superior to that of the conventional schemes. At the same time the integrated performance of the proposed algorithm in WAN is also better than that of the conventional schemes.2. An adaptive PID controller based on neural network is proposed as a new AQM algorithm. Simulation results show the the performance of response time and queue error of the proposed algorithm in LAN is superior to that of the conventional schemes. The performace of the proposed algorithm in WAN is also better than that of the conventional schemes.3. A differential advanced control algorithm is proposed as a new AQM algorithm. The integrated performance of the proposed algorithm in LAN is similar to that of the PID scheme while the performance of the proposed algorithm in WAN is obviously superior to that of the conventional schemes.