On the fairness improvement of channel scheduling in optical burst-switched networks

In the past years, several signaling protocols were proposed for OBS networks and the most popular one is the Just-Enough-Time (JET) protocol. JET not only efficiently utilizes the network capacity, but also effectively reduces the end-to-end transmission delay. However, the most critical defect of JET is its intrinsic deficiency: Fairness. The fairness problem is a traditional problem common to various kinds of networks. It results in a phenomenon that bursts with a shorter number of hops are generally favorized and hence deteriorates the network utilization as well. In this article, we investigate this problem and propose a fair channel scheduling algorithm as a solution. Usually there is a tradeoff between fairness and blocking performance. Accordingly, the objective of our scheme is to achieve a balance between the two conflicting metrics as much as possible. In our scheme, each burst is associated with a dynamic priority which is defined by several characteristics of the burst. When contention occurs, the proposed scheme picks the preferable burst and drops the other one according to their priorities. From simulation results, we observed that the proposed scheme could improve fairness without causing significant reduction in dropping performance. Furthermore, it increases the effective link utilization as well.