Analytical modeling of multi-channel optical burst switching with multiple traffic classes

Ankara : The Department of Electrical and Electronics Engineering and the Graduate School of Engineering and Sciences of Bilkent University, 2011.Thesis (Master's) -- Bilkent University, 2011.Includes bibliographical references leaves 58-59.In this thesis, we study an Optical Burst Switching (OBS) node with links carrying multiple wavelength channels (called hereafter channels) with multiple traffic classes. We assume that offset-based service differentiation is used to differentiate among these traffic classes in terms of packet loss probabilities. We first propose a basic scheme, called bLAUC (Basic Latest Available Unused Channel) for channel scheduling. Although practicality of the bLAUC scheme is relatively limited when compared to other conventional schedulers such as LAUC, we study bLAUC in this thesis due to its tractability to analysis and moreover bLAUC possesses certain crucial properties of conventional schedulers. We then propose an iterative procedure to approximate per-class loss probabilities for the OBS link of interest when packet arrivals to the link are Poisson and packet lengths are exponentially distributed. In our iterative procedure, we model a multi-channel OBS link with Poisson arrivals by a single channel Markov fluid queue with occupancy-dependent packet arrival intensities. The proposed procedure provides acceptable approximations for a wide range of scenarios with relatively low complexity. Consequently, the proposed procedure can be used in optimization problems concerning multiclass OBS and in finding guidelines to effectively utilize OBS resources under loss probability constraints.Dinç, VolkanM.S

Modeling and system improvements for wavelength conversion in optical switching nodes

Ph.DDOCTOR OF PHILOSOPH