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Design and optimization of packet switching and traffic grooming in WDM optical networks
Optical packet switching is a long-term strategy to provide high-speed transmission, data transparency, and reconfigurability. Optical buffers are used in the switches to resolve contentions that occur whenever two packets are destined to the same output at the same time slot. Due to the lack of optical random access memory, fiber delay line (FDL) is currently the only way to implement optical buffering. In general, optical buffering structures can be categorized in two classes: feed-forward and feedback, both of which have advantages and disadvantages. In this research, we proposed a more effective hybrid buffering architecture that combines the merits of both schemes. It requires smaller optical device sizes and fewer wavelengths and has less noise than feedback architecture. At the same time, it can facilitate preemptive priority routing which feed-forward architecture cannot support. Based on this architecture, we described two switch designs—single plane and multiple plane. The numerical results showed that the new switch architecture can significantly reduce the packet loss probability. ^ The objective of traffic grooming is to save electronics cost by effectively assigning low-rate circuits onto high-speed channels. Generally, we can treat the traffic grooming problem as two steps: circuit construction and circuit grooming. In this research, we focused on developing efficient algorithms for circuit construction. Two heuristics based on Random Hill-climber and Simulated Annealing were proposed. Our algorithms are more aggressive in splitting the connections to achieve efficient circuit construction. Numerical results showed that the algorithms have good performance in reducing the low-rate circuit number and end node number. ^ We also studied the problem of weighted edge-decompositions of graphs which is related to circuit grooming. The research was focused on grooming symmetric traffic that we can always construct full low-rate circuits. The objective is to minimize the number of add/drop multiplexers by using the minimum number of wavelengths. Through numerical estimates, we obtained useful tight bounds of some special cases of k-decompositions of a graph. ^
Li, Lin, "Design and optimization of packet switching and traffic grooming in WDM optical networks" (2004). ETD collection for University of Nebraska - Lincoln. AAI3147145.