Physical layer impairments aware routing and spectrum allocation algorithm for transparent flexible-grid optical networks

Abstract

In this paper, we discuss physical layer impairments (PLIs) aware routing and spectrum allocation (RSA) algorithm for the transparent flexible-grid optical networks. The flexible-grid optical networks have the capability of delivering data with multi-rate, multi-reach, high spectrum efficiency, high flexibility, and low bit error rates (BER). However, in transparent flexible-grid optical networks, as the transmission distance increases, optical signals are subject to traverse over many bandwidth-variable wavelength cross connects (BV-WXCs) and multiple fiber spans. As a result, the PLIs get accumulated and are added to the optical signal. These accumulated impairments degrade the signal quality to an unacceptable level at the receiver. Hence, the quality of transmission (QoT) falls below the acceptable threshold value and making it hard for the receiver to detect the signal properly. This problem has not received enough attention in the literature yet. Therefore, our objective is to develop an impairments aware RSA algorithm, which establishes the QoT satisfied flexpath based on the available resources and the quality of the signal available at the receiver. We formulate the PLIs-aware RSA problem as an integer linear program (ILP) that provides an optimal solution. We propose a PLIs-aware heuristic algorithm for large-size networks where ILP is not efficient. Using extensive simulation results, we compute the total blocking probability and the spectrum efficiency. The results show that our algorithm outperforms in terms of blocking probability and spectrum utilization.