Impact of filter sharpness on the performance of elastic optical networks

Elastic optical network (EON) technology arises as a promising solution for future high-speed optical transport networks, inasmuch as it can provide superior flexibility and scalability in the spectrum allocation for seamlessly supporting a disparity of services, while coping with the rapid growth of Internet traffic. Spectrally efficient lightpath establishment in EONs is enabled by recent developments in flex-grid transceivers and wavelength selective switches (WSS), which are the key players in determining the amount of spectrum that needs to be reserved for a connection as well as the guard band (GB) required between adjacent channels, since the imperfect shape of the filters degrades the spectrum utilization efficiency of the network. In this paper, we focus on the impact of the filter sharpness on the performance of EONs from the networking perspective. In this regard, we initially quantify the effect of the sharpness of a transmitter Nyquist shaping filter and an LCoS-based WSS filter on the amount of spectrum required for efficient connection establishment. Subsequently, we investigate the practicality of moving to finer frequency slot sizes and, based on extensive simulation results, evaluate the improvement in terms of network blocking probability that can be obtained by using sharper filters.