A Simulation Study of Rate and Queue Based on Active Queue Management

摘要

Now a days, e-Queues are built up everywhere where customer online-service is necessary such as in banks? e-Service, enterprises? e-Business, etc. In order to enhance Active Queue Management (AQM) and Quality of Service (QoS) algorithms are frequently employed due to its efficiency in congestion avoidance as well as the differentiated forwarding of packets. This research aims at developing a novel AQM algorithm to better QoS in terms of congestion prediction, packet loss, queuing delay and link utility, etc. Upon the traditional designs of AQM, this research establishes a new integrated AQM scheme (RQ-AQM) by employing current queue length and input rate to calculate the packet marking/dropping probability. In this way, the feedback rate control enables to respond to congestion rapidly, decreasing the packet loss from buffer overflow. Meanwhile, stabilizing the queue feedback control around a given target to achieving predictable queuing delay and lower delay jitter. Thus, the main feature of the design is to use coefficients of both proportional rate control and proportional integral queue length control. And to simplify parameter setting, the control parameters were scaled by the link capacity C to normalize the rate and by the Bandwidth-Delay Product BDP to normalize the queue length, respectively. The stability performance of RQ-AQM was tested via simulation under several conditions. The results proved that it is able to maintain the queue length around the given target. Also, the comparison results with other AQM schemes including RED, ARED, PI controller, AVQ and REM, demonstrated the superiority of RQ-AQM in low packet loss, faster convergence to target queue length and closest to the target queue length.