Wavelength assignment scheme for WDM networks with limited-range wavelength converters

We propose a new wavelength assignment scheme that improves the blocking probability of WDM networks that use limited-range wavelength converters. Limited-range wavelength converters are attractive for wavelength-routed networks, given current technology, since they offer good utilization of the wavelength resource and improved blocking probability. However, their conversion ranges are limited; the maximum difference between the input and the output wavelengths is restricted. Thus we must take into account the existence of these limited-range wavelength converters. In our proposed scheme, each connection request is assigned a different wavelength according to its hop number. We tend to use different wavelengths for connection requests with different hop numbers. As a result, we can reduce the blocking probability by two decades compared with simply assigning the shortest available wavelengths. In addition, the scheme allows the number of wavelength converters used in each node to be reduced with almost no degradation in blocking probability. Simulation results show that the proposed scheme can reduce the wavelength converters by about 20% on the simple ring network and by 37.5% on the 14-node NSFNet network.