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Abstract
One of the main objectives of this thesis is to thoroughly investigate contention resolution in optical burst switched networks (OBSNs) using wavelength conversion. Specifically, we propose a mathematical model for perfonnance evaluation of an OBS core node having either no, partial, or full wavelength conversion capability while assuming short-range dependent (SRD) Poisson traffic arrivals. In the prposed model, each output port is mode led as an M/M/w/w queue to derive two perfonnance measures; namely, the steady state throughput and the burst loss probability. In addition, a simulation work validates the model results which prove to be more accurate than previous models proposed. Optimum values for the wavelength conversion capability are reached at different traffic conditions while taking into consideration the cost of implementation of such sophisticated devices.
Next, we propose another mathematical model for performance evaluation of an OBS core node employing either no or full wavelength conversion while assuming long-range dependent (LRD) traffic arrivals mode led by Pareto distribution. In our model, each output port is mode led as a GI/M/w/w queue to calculate the burst loss probability. Results of this model are compared with those of the first model that assumes Poisson arrivals to investigate the difference between the system performance in both cases. Results show that assuming SRD Poisson arrivals gives optimistic results compared to the more accurate LRD Pareto arrivals imitating the real networks LRD traffic streams.
Finally, we propose employing spectral-amplitude-coding optical code division multiple access (SAC-OCDMA) as a contention resolution technique in OBSNs. The proposed system architecture is presented including a new all-optical technique proposed for cancelling multiple access interference. Performance evaluation of the proposed system in media access control (MAC) and optical layers is performed to derive the overall burst error rate in three cases: no, partial and full code conversion capabilities taking into account receiver thermal, shot and dark current noises. Results show that an improvement is attained by employing SAC-OCDMA instead of WDM in the optical layer underneath an OBS-based MAC layer. In addition, results prove that a massive performance improvement is achieved by employing code converters. At last, optimum number of codes with which the system should be designed is reached at different traffic scenarios.