Quality of Transmsision Aware Routing and Wavelength Assignment Algorithm for Blocking Minimization in Translucent Optical Networks

In Optical Transport networks, the optical reach is defined as the maximum distance (number of hops) a lightpath connection can span before the intelligence of the signal it is carrying to unrecoverable state as a result of the degradation in the signal to noise power ratios. When the signal to noise ratio has degraded below a certain acceptable threshold, regeneration is necessary. Optical Transport networks will normally incorporate optical repeaters throughout to facilitate signal reach for all the lightpath connection establishments. Such networks are classified as being Translucent. The role of the sparsely spaced optical repeaters is to refresh the degraded optical signals so that an acceptable quality of transmission (QoT) can be guaranteed by the network operator. The deployment of such units where necessary throughout the network leads to an escalation to both capital as well as operational expenditures. It is however necessary that network designers strike a balance between the network operating costs versus renderable quality of service (QoS) to end users. In light of this challenge, in this paper we propose and analyze a QoT-Aware routing and wavelength assignment algorithm (QARWA) that seeks to minimize blocking of data bursts traversing the network. The QoT blocking considers the effects of various linear as well as nonlinear impairments. The proposed model can be infused with other algorithms that attempt to calculate wavelength blocking per route and also per available layer. We also further enhance the same algorithm's efficacy by introducing its QoT aware guaranteed RWA (QGRWA) equivalent. The novelty of the scheme is in taking into account physical layer impairments, as well as signal quality when computing candidate routes for a given source to destination pair. The proposed algorithm's overall promising performance is validated via analytical and simulation means.