Authors
college of engineering, University of information technology and communications, Baghdad, Iraq
Abstract
The network congestion is an essential problem that leads to packets
losing and performance degradation. Thus, preventing congestion in the
network is very important to enhance and improve the quality of service. Active
queue management (AQM) is the solution to control congestion in TCP network
middle nodes to improve theire performance. We design a linear quadratic
(LQ)-servo controller as an AQM applied to TCP network to control congestion
and attempt to achieve high quality of service under dynamic network
environments. The LQ-servo controller is proposed to provide queue length
stabilization with a small delay and faster settling time. The designed controller
parameters are tuned by using the particle swarm optimization (PSO) method.
The PSO algorithm was fundamentally applied to find the optimal controller
parameters Q and R, such that a good output response could be obtained. The PI
controller is examined for comparison reasons. The MATLAB simulation result
shows that the controller is more effective than the PI in reaching zero steadystate
error with better congestion avoidance under the dynamic network
environment. Moreover, the proposed controller achieves a smaller delay and
faster settling time.
Keywords
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