Abstract
The Resilient Packet Ring (IEEE 802.17) fairness algorithm is simple, but exhibits some weaknesses. The bandwidth allocation severely oscillates when the traffic is unbalanced. Several algorithms have been proposed in recent years to overcome this issue. For example, the proportional controller is used for solving the fairness problem. The proportional controller is able to converge to the fair rates with no oscillations at the steady state. Unfortunately, the controller shows bandwidth oscillations and becomes unstable if the network delay is significant. In this paper, the impact of the delay is studied analytically and through simulation. Also, the Smith's principle is used to compensate the ring delay. Moreover, the controller gain is tuned using a fuzzy logic system. The performance is evaluated through simulation and the results show that the proposed adaptive predictive proportional controller assures fairness, stability and high bandwidth utilization even in ring network with large delay.