Group-Scheduling for Multi-Service Optical Burst Switching (OBS) Networks

Abstract

We propose a new burst scheduling mechanism for Optical Burst-Switched (OBS) networks. The new approach is made possible by gathering data bursts into groups and performing the scheduling decision for each group collectively. In OBS group-scheduling, bursts will not be considered for scheduling until a pre-defined time period elapses, during which the group of burst header packets would be gathered. By transforming a set of data bursts into a set of corresponding time intervals, the problem of scheduling these bursts is transformed into a combinatorial optimization problem. Graph algorithms are applied to obtain the maximum number of non-overlapping bursts. The proposed OBS groupscheduling scheme is shown to improve the performance of OBS networks over existing scheduling schemes in terms of burst loss probability and channel utilization. With an extension through a sequential optimization, using a Branch-andBound technique, the proposed scheme can support multiple classes of service. It is shown that the new scheduling approach has several desired characteristics including fairness and service differentiability among classes in terms of burst loss probability and channel utilization.

A wavelength assignment and traffic control scheme in reservation slotted OBS rings

“…An appropriate wavelength assignment not only has better bandwidth utilization but also supports CoS. Some wavelength assignment methods been proposed for OBS networks [7]- [9]. One of them, called the group scheduling (GS) proposed in [11], is with better performance.…”