A Switched Rate-based Robust Queue Management for Wireless Access Networks

In a communication network, transmission control protocol (TCP) is used to avoid congestion through which the sources with small round trip time (RTT) allocate the bottleneck link unfairly. On the other hand, the bottleneck link capacity is time-varying in wireless access networks due to the fading effects and errors in the acknowledgment packets. Therefore, queue management is more sophisticated in wireless networks than that in wired ones. Also, when the number of the sources changes, the network acts as a switched system in which non-zero initial values cause the response not to converge to the desired value. The main contribution of this paper is to design a switched rate-based robust queue management (SRRQM) to control the congestion contemporary with weighted fairness and maximum utilization compatible with wireless access networks. Moreover, a procedure called initial value compensation (IVC) is designed to overcome the non-zero initial value effects. Two degree of freedom multi-loop internal model (TDF-MIM) method is used for robust congestion control. The utilization factors are designated proportionally to user's RTT values to ensure weighted fairness and maximum utilization. To the authors' knowledge, this is the first time that a SRRQM is designed for a wireless access network with the advantages of weighted fairness, maximum utilization and robustness against capacity variation, PER and changing in the number of the sources. Analytical and simulation results demonstrate the efficacy of the proposed procedure.