New QoT-Aware Rerouting Algorithms in WDM All-Optical Networks

摘要

The wavelength continuity constraint and the wave-length integrity constraint imposed by Wavelength-Division Multiplexing (WDM) all-optical networks have been, for a long time, the main constraints to be considered when solving the Routing and Wavelength Assignment (RWA) problem in such networks. However, in addition to the two aforementioned constraints, a third constraint cannot be neglected anymore. This constraint is related to the lightpaths' Quality of Transmission (QoT), which might become potentially unacceptable when the optical signal propagates through long distances. Indeed, in WDM all-optical networks, no signal regeneration at intermediate nodes is allowed which induces some impairments in the transmission signal. Since these impairments continue to degrade the signal quality as it progresses toward its destination, the received Bit Error Rate (BER) at the destination node might become unacceptably high. This result might lead to inefficient utilization of network resources resulting in higher rejection ratios. This is especially severe when dynamic lightpath demands are considered. In this paper, we propose to use rerouting as a solution to improve the network throughput. We investigate and compare three different rerouting categories, namely, passive rerouting, active rerouting and hybrid rerouting. To the best of our knowledge, this is the first attempt to use active and hybrid rerouting for optimizing WDM all-optical network throughput with transmission impairments consideration. Multiple simulation studies have been carried out on different network topologies to evaluate and compare the performance of the proposed algorithms.