An irregularly slotted ring scheme for contention-free optical burst switching

Optical burst switching (OBS) is a promising way to efficiently use the massive bandwidth in wavelength division multiplexing (WDM) networks. However, the problem of contention between bursts is hard to be solved in OBS networks with general topology. For that reason, the conception of contention-free OBS ring is proposed. In recent years, several OBS ring schemes have been designed. According to the number of transceivers installed at each node, the schemes can be roughly divided into two classes: single-transceiver schemes and multi-transceivers schemes. Among which, multi-transceivers schemes are more efficient than single-transceiver ones. There are two existing multi-transceivers schemes, LightRing and SWING, yet both of them have disadvantages. The LightRing scheme has a high queuing delay and needs large buffers, while the SWING scheme not only needs a large number of fiber delay lines but also has a specific requirement to the girth of the ring. In this paper, we design another multi-transceivers OBS ring scheme named irregularly slotted OBS ring (IS-OBS-Ring). In the IS-OBS-Ring scheme, all data wavelengths are slotted and slots on different wavelengths are not synchronously but irregularly distributed. Simulation results show that the performance of IS-OBS-Ring is further better than the LightRing scheme and similar to the SWING scheme. However, the IS-OBS-Ring scheme can overcome the disadvantages of both the LightRing scheme and the SWING scheme.