| Summary: | 碩士 === 國立交通大學 === 電信工程系所 === 93 === In recent years, synchronous optical network (SONET) ring networks have been widely deployed for the optical network infrastructure. The progresses of optical networks evolve with time; meanwhile, the carried traffic streams surge. The transmission capacity of an optical network largely increases because of the development and application of wavelength division multiplexing (WDM) technologies. However the required bandwidth of a traffic stream is also much smaller than the bandwidth capacity of a wavelength. Thus, in order to efficiently utilize the network resources, many lower-speed traffic streams can be multiplexed onto a high-speed wavelength by traffic-grooming technique.
In the thesis, we consider the traffic grooming problem, which the property of the traffic is dynamic and nonuniform traffic. Our objective is to effectively reduce the new call blocking rate and maximize the utilization efficiency of the wavelengths which are used by the system. Integer linear problem (ILP) methodology is applied to formulate for this problem. And, in order to solve the ILP, we first propose a simulated annealing-based traffic grooming (STGA) algorithm to obtain the optimal solution. However, the STGA algorithm is infeasible due to its computation complexity. Alternatively, we propose a heuristic algorithm, called a heuristic-based traffic grooming (HTGA) algorithm.
There are the three main operations in HTGA algorithm: operation of traffic grooming, operation of wavelength assignments, operation of traffic rearrangement. The main purpose of these operations is to achieve the better system utilization without changing the lightpath topology as could as possible.
From the simulation evaluation, network performance measures are observed. For system utilization, the HTGA algorithm is only 10% less than the STGA algorithm, whereas the computation complexity of the STGA algorithm is much larger than that of the HTGA algorithm. In addition, the number of rearranged lightpaths by the HTGA algorithm is fewer than the ones by the STGA algorithm. From these results, we can conclude that the HTGA algorithm is a feasible and attractive algorithm.
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