Design and Performance Analysis of OBS Network Using Hybrid Contention Resolution Technique

Optical burst switching (OBS) is a promising switching technology for realization of terabit optical network because it offers a very high bit-rate transport service that is potentially bandwidth-efficient and costeffective in terms of network infrastructure. However, the lack of optical processing capability of OBS technology results in increased blocking probability and limits the network performance. Efficient contention resolution is therefore necessary. OBS networks are usually implemented using different contention resolution protocols but in particular, the analysis of wavelength conversion schemes and fibre delay line (FDLs), is required more attention as these two are easily realizable contention resolution components. Wavelength conversion is the process of converting a wavelength on an incoming channel to another wavelength on the outgoing channel. FDLs can be used to delay bursts until the contention situation is resolved and the original destination wavelength becomes available. Performance of wavelength converters may be restricted by number of available wavelength converters, sharing strategy and degree of conversion. Theoretically a burst may recirculate multiple times through FDL bank, although signal degradation issues may limit the number of recirculations. Hence it difficult to achieve desired contention resolution performance by using any one type of the conventional technique. In this paper a hybrid contention resolution scheme for OBS network has been proposed with the combination of wavelength converters and FDLs to achieve better contention resolution performance. Appropriate mathematical models have been developed to calculate the gain and blocking probability of the proposed scheme. Results are validated through proper simulations.