Practical design of PID controllers for TCP/AQM networks

Internet users rely on the good capabilities of TCP/IP networks for dealing with congestion. The network delay and the number of users change constantly, which might lead to transmission problems. Usually, they are handled following algorithms such as drop tail or random early detection (RED). In recent years, feedback control techniques are providing practical solutions for this problem. In this context, this paper presents a methodology to design a PID with a gain scheduling and improved design robustness that allows the network to deal with control congestion under a variety of network configurations, giving good performance. The proposed technique is demonstrated through simulations.