Group-Scheduling for Optical Burst Switched (OBS) Networks

Abstract

To date, all of the proposals for burst-scheduling techniques have considered scheduling individual bursts. We introduce a new scheme called OBS group scheduling. In this approach, a burst is represented by an interval of time. The process of scheduling a number of bursts, thus, turns to be a process of fitting a set of the corresponding time intervals on a channel time line that represents a channel-time resource. By doing so, we can formulate the scheduling process as a combinatorial optimization problem. Then, graph theory is applied to schedule as many non-overlapping intervals as possible onto the channel time line. The underlying concept of the group scheduling is that of briefly delaying the scheduling of a burst so that a much better decision can be made about a number of bursts all-together. This scheme is shown, through simulations, to improve performance in terms of burst loss probability and channel utilization over existing schemes.