Retracted Article: Performance benefits of regeneration flexibility and modulation convertibility in elastic optical networks

Abstract

In planning of the elastic optical networks (EONs), the traditional approach of regeneration node(s) number minimization and the assumption of same modulation format over every segment of lightpath results in the (i) utilization of modulation formats which are less spectrally-efficient, and (ii) unneeded resource(s) loss over shorter route segments which may use modulation formats that are more spectrally-efficient. In this work, we investigate the performance benefits that can be obtained by the introduction of intentional signal regeneration, modulation and spectrum conversion in non-transparent (i.e., translucent) EONs which are based on super-channel transmission. We examine and compare three different cases that may be used to provision the lightpaths which are translucent viz., a basic case of regenerator(s) minimization, and two cases which provision flexible signal regeneration and modulation conversion. For the aforementioned, we develop the routing and spectrum allocation with transceiver and regeneration allocation (RSAwTCRA) problem which, apart from the traditional RSA constraints, also accounts for the (i) regeneration site(s) selection, (ii) modulation format(s) adaptation, and (iii) transceiver(s) assignment to the lightpaths. We develop (i) an integer linear programming method to formulate the RSAwTCRA optimization problem and, (ii) a heuristic (scalable) algorithm to generate the RSAwTCRA solutions. Our simulation results demonstrate that with deliberate signal regeneration and optical carriers’ modulation format(s) adaptation, gains in both, the spectrum and transceiver(s) utilization are achievable for the networks with long distances; however, the savings are negligible for the network with small distances.