Traffic-Adaptive Re-Configuration of Programmable Filterless Optical Networks

Abstract

In view of incoming 5G mobile communication, network operators must upgrade their network capacity while capping capital and operational expenditures. Filterless Optical Networks (FONs) are emerging as a cost-effective technology as they eliminate costly active switching elements, the Reconfigurable Optical Add-Drop multiplexers (ROADMs) based on Wavelength Selective Switch (WSS), by replacing them with passive devices as optical power splitters/combiners. However, eliminating active switching and filtering components enforces signal broadcast on all the outputs of the passive splitters, resulting in the transmission of optical signals over unintended links and hence in higher spectrum occupation with respect to wavelength-switched optical networks (WSONs) based on active devices. To mitigate spectrum waste, FONs can be augmented by deploying programmable optical switches, which increase network flexibility as they allow re-configuration of fiber trees established in FONs to accommodate demands. This filterless network is referred to as Programmable FON (P-FON). In this paper, we propose a traffic-adaptive heuristic algorithm, namely Adapt P-FON, for the re-configuration of programmable optical switches in FONs. The algorithm performs routing and spectrum assignment for traffic demands and also provides optimized configuration of programmable optical switches such that the overall spectrum utilization in the network is minimized. We evaluate the advantages of P-FONs, in terms of spectrum utilization and equipment cost, against FONs and WSON scenarios. Results show that P-FONs have significant advantages in terms of spectrum utilization in comparison to FONs (up to 60%), and, at the same time, cost savings (up to 90%), considering cost of splitters, WSSs and programmable switches, in comparison to WSON.