Modeling analysis partial wavelength converters and deflection routing by using fourdimensional markov chains to resolving contention problem in obs networks

Abstract

In Optical Burst Switching (OBS) network, the contention is one of the big problem. A contention occurs when more than one burst require the same output wavelength channel in the same time. The methods used to resolve this problem are deflection routing, optical buffer (FDL) and wavelength conversion. With the deflection routing, the contending burst is sent in another route rather than primary route towards it’s destination. In this case of wavelength conversion, the current wavelength of burst is changed to another free wavelength channel. In this paper, we study the effect of wavelength conversion with partial wavelength converters (PWCs) and deflecting routing by using four-dimensional Markov chain model in resolving the contention problem in OBS Networks. This approximated continuoustime Markov chain (CTMC) can be solved by the matrix-geometric method, which involves the computation of the rate matrix Q. We present an efficient algorithm with the polynomial time complexity to compute the rate matrix Q.