Robust RMSA design for shared backup path protection based EON against nonlinear impairments

Abstract

We focus on quality of transmission (QoT) guaranteed routing, modulation, and spectrum allocation (RMSA) in shared backup path protection (SBPP) based elastic optical networks (EONs) in the presence of nonlinear impairments. Allocating a suitable modulation format (MF) to ensure end-to-end QoT (E2E QoT) in a survivable EON offers critical challenges because each single link failure results in the failure of different network connections. As a consequence, different working and backup path allocations exist in the network for different failures, which lead to different nonlinear interference (NLI) power on any frequency slots (FSs). This demands a robust RMSA design to decide the suitable MF for each FS to ensure the E2E QoT under two scenarios: any single link failure and no failure. For this purpose, we propose a robust SBPP-NLI aware (SBPP-NLIA) algorithm to ensure E2E QoT with a multi-objective function that enables the joint sharing of backup FSs as well as transceivers and minimizes the overall network fragmentation. In the process, we introduce robust bitloading in our SBPP-NLIA to allocate different MFs for different FSs where we also perform optimal MF allocation for each FS of every connection. Next, we ensure the QoT of existing connections while establishing each new connection without reserving any margin. To achieve this with less complexity, we propose a recursive method to calculate the NLI for existing connections. Simulation results demonstrate that our proposed SBPP-NLIA performs 10.01% and 14.19% better in terms of, respectively, the bandwidth blocking probability and fragmentation compared to a full-load assumption scheme with an 85 Tb/s traffic load.