Summary |
Wavelength Division Multiplexing (WDM) is a promising technology to utilize the huge bandwidth of optical fiber. Wavelength-routed all-optical network is a suitable architecture to serve as the backbone of wide-area networks by providing lightpath services. Blocking has been the key performance index in the design of a wavelength-routed network. Existing research demonstrates that an effective routing and wavelength assignment (RWA) algorithm and wavelength conversion are the two primary vehicles for improving the blocking performance. However, these two issues have largely been investigated separately in that the existing RWA algorithms have seldom considered the presence of wavelength conversion, while the wavelength converter placement algorithms have largely assumed that a static routing and random wavelength assignment algorithm is employed. In this dissertation, we first investigate the wavelength converter placement problem for different RWA algorithms. Under the fixed-alternate routing (FAR) algorithm, we propose a heuristic algorithm called Minimum Blocking Probability First (MBPF) for wavelength converter placement. Under the least-loaded routing (LLR) algorithm, we propose another heuristic algorithm called Weighted Maximum Segment Length (WMSL). We observe that the proposed algorithms not only outperform existing wavelength converter placement algorithms by a large margin, but they also can achieve almost the same performance comparing with full wavelength conversion under the same RWA algorithm. The second work is to investigate the dynamic routing algorithm in the presence of wavelength conversion. We show that existing dynamic routing algorithms cannot utilize the fiber link resources efficiently in the presence of wavelength conversion. We then propose a weighted least-congestion routing (WLCR) algorithm that considers both the distribution of free wavelengths and the lengths of each route jointly. Finally, we propose the sparse-partial wavelength conversion architecture, which can save the number of wavelength converters significantly. In this architecture, two problems have been examined. The first one is the wavelength assignment problem, and the second one is the converter placement problem. |