Multiwavelength optical networks with limited wavelength conversion

This paper proposes optical wavelength division multiplexed (WDM) networks with limited wavelength conversion that can efficiently support lightpaths (connections) between nodes. Each lightpath follows a route in a network and must be assigned a channel on each link along the route. The load /spl lambda//sub max/ of a set of lightpaths is the maximum over all links of the number of lightpaths that use the link. At least /spl lambda//sub max/ wavelengths will be needed to assign channels to the lightpaths. If the network has full wavelength conversion capabilities, then /spl lambda//sub max/ wavelengths are sufficient to perform the channel assignment. Ring networks with fixed wavelength conversion capability within the nodes are proposed that can support all lightpath sets with load /spl lambda//sub max/ at most W-1, where W is the number of wavelengths in each link. Ring networks with a small additional amount of wavelength conversion capability within the nodes are also proposed that allow the support of any set of lightpaths with load /spl lambda//sub max/ at most W. A star network is also proposed with fixed wavelength conversion capability at its hub node that can support all lightpath sets with load /spl lambda//sub max/ at most W. These results are extended to tree networks and networks with arbitrary topologies. This provides evidence that significant improvements in traffic-carrying capacity can be obtained in WDM networks by providing very limited wavelength conversion capability within the network.