Reconfigurability of single-hub WDM ring networks

We study the benefit of reconfigurability for single-hub WDM ring networks with dynamic single-hubbed traffic. We show that using reconfigurable wavelength add-drop multiplexers (R- WADMs) in place of non-reconfigurable ones can reduce the number of expensive line terminating equipments (LTEs) by a factor of W, where W is the number of wavelengths in the network. In addition, we show that for a general class of traffic, optical networks using R-WADMs guarantee to be (almost) as bandwidth-efficient as full wavelength add-drop networks (that is, opaque networks). For such traffic, we introduce several fast algorithms that achieve or approximate the optimal performance guarantees. The comparison between reconfigurable networks and opaque networks is quantified using a performance metric called capacity ratio, which captures the relative throughput performance of a reconfigurable network compared to the opaque network.