Polylogarithmic competitive algorithm for energy minimization in optical WDM networks

We study the energy minimization problem (EMP) in the optical WDM networks with arbitrary topologies. It is assumed that the traffic requests can arrive at and depart from the network arbitrarily, and idle network devices can be dynamically switched off to save energy. For each traffic request R, we need to specify a wavelength ?R and a fibre in each link along its path to carry ?R. The objective is to minimize the energy consumption incurred by the active devices over the entire network for any time period [0, t]. In this paper, a randomized online algorithm is proposed for EMP. Particularly, for each traffic request, our algorithm only needs O(1)-time to determine the wavelength, and the fibre allocation procedure can be performed in a fully distributed manner in each link with polynomial time. The competitive ratio of our algorithm is bounded by O(log μ·log hmax), where μ represents the number of wavelengths carried by each fiber and hmax represents the holding time of the longest traffic request.