Key Link Factor for Performance Optimization in WDM Networks with Sparse Wavelength Conversion

Blocking probability has been one of the significant parameters in the design of WDM optical networks. In most of the network topologies the probability for each link to be occupied is different. There are always some links which are more likely to be used than others which can be denoted as key links. The existing routing algorithms do not take this important factor into account significantly. The network performance deterioration is more likely caused by certain key links of the network, which is related to static factor such as particular network topology, and dynamic factors such as wavelength exhausted rate as well as the number of free wavelengths available on a link. In the proposed approach, the key links are identified based on the link usage factor of a link to minimize the capacity exhaustive blocking in WDM networks. The concept of key links is incorporated in wavelength converter placement strategies for performance optimization in WDM networks. For sparse wavelength conversion the wavelength converters are placed in the nodes that connect the key links with higher normalized frequency of usage. The performance of the proposed approach is studied for various set of wavelengths and compared over full wavelength conversion and no wavelength conversion conditions in terms of blocking probability and link utilization. The proposed approach closely tracks the performance of full wavelength conversion. Keywords-Link Utilization, Blocking probabilities, Routing and wavelength Assignment (RWA), Wavelength Division Multiplexing (WDM)