Design of PID Controllers for TCP / AQM Wireless 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 approaches such as drop tail or random early detection (RED) algorithms. During the last few years, automatic control techniques are providing practical solutions. Moreover, if there are wireless links, congestion control is more difficult to detect. This paper presents a methodology to design a PID controller with a linear gain scheduling that allows a network with wireless links to deal with control congestion under a variety of configurations. The proposed technique is demonstrated through non-linear simulations and compared with the classical PID