Wavelength Division Multiplexing (WDM) has been a widely-used multiplexing technique in large-scale optical telecommunication networks during the past few decades. Routing and Wavelength Assignment (RWA) is a fundamental process that involves determining the optimal path (routing) and assigning specific wavelengths to incoming data streams to ensure efficient and reliable transmission in WDM networks. This dynamic allocation of wavelengths allows for flexibility and adaptability in handling diverse traffic demands, making RWA a crucial mechanism for maximizing the capacity and performance of optical communication systems.
This project aims to find intrinsic factors that influence RWA performance in WDM and propose novel RWA approaches with enhanced performance. Existing dynamic RWA methods are reviewed from the literature and simulated in a self-built performance evaluation model. As the availability of every edge at every wavelength is constantly changing, we can transform the WDM network into a multi-layer temporal network structure. In order to uncover the essential reasons for the differences between the performances of the different methods, we investigate the multi-layer temporal network with graph theoretic analysis to explore correlations between specific multi-layer metrics and RWA performance. A few single-layer network connectivity metrics are applied in multi-layer networks including the number of connected components, the size of the largest components, the spectral radius, the algebraic connectivity, the effective resistance, the sum of betweenness, and the number of reachable node pairs. The experimental results show that the maximum value of spectral radius and algebraic connectivity over all layers are the best 2 multi-layer metrics describing the performance of the RWA methods.
Building upon this analysis, four new routing methods are proposed based on the previous methods and the two best-adapted multi-layer graph metrics, including the Least Spectral Radius Deduction (LSRD), Least Algebraic Connectivity Deduction (LACD), Least Hopcount and Congestion Path (LHCP) and Congestion Weighted Shortest Path (CWSP) methods. All new methods are fitted in the evaluation model and it has been proven that the CWSP method has better performance compared to all other RWA methods based on its improvement of selected multi-layer graph metrics.