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Abstract
In this thesis, we propose two contributions in the field of optical ; communication networks. The first contribution is an analytical mathematical model, fwhile the second contribution is the proposal of a whole framework of a new optical ; communication system.
First, ’a mathematical model is proposed to study the performance of a core ” node in an optical burst switched network (OBSN) that does not have any wavelength ,. converters in its resources. In this model, the equilibrium point analysis (EP A) ” technique is used to derive the steady state throughput and the burst loss probability
while assuming that the maximum allowed number of arrivals to the OBS core node, in a given time slot, is two. This work is an enhancement for a previous work that uses the same technique to derive the same performance measures but with the assumption that the maximum allowed number of arrivals to the OBS core node is one [1]. A simulation work is constructed assuming a more realistic case where the traffic arrivals to the core node follow a Poisson distribution. Results obtained from the enhanced mathematical model are consistent with that of simulation work. This consistency holds for a wider range of traffic load than that of the previous model.
Second, a framework for the implementation of optical code division multiple ac::cess (OCDMA) is proposed as a contention resolution technique in OBSNs. ’.lnspired by the idea of Kamakura et al. [2] to use the OCDMA system based on ,optical orthogonal codes (OOC-OCDMA) in OBSNs, we propose a detailed
description for the framework showing the whole architecture of the system while maintaining the data bursts (DBs) in the optical domain in the core network. During the implementation of the OOC-OCDMA in OBSNs, optical links between the nodes are implemented using AllWave fibers due to the great bandwidth offered by such fiber which is convenient with the vast bandwidth required to accommodate time¬spread OCDMA signals. The abundant spectrum available on such fiber enables the multiplexing of DBs over the wavelengths and then multiplexing the DBs on the same wavelength over the codes. Furthermore, an intensive analysis for the
performance of the proposed system is presented in MAC and optical layers deriving the overall burst loss probability while assuming full code conversion capability. Results show that the proposed system is more immune to noise than the system using wavelength division multiple access (WDMA) underneath OBS at low power levels. Finally, optimum values of number of codes at different code lengths are reached and optimum code lengths at different values of number of codes are also
’.obtained.