QoT-aware tree selection, routing, modulation, and spectrum assignment for filterless EONs over the C + L-band

Abstract

Filterless optical networks (FONs) as an economical solution use passive couplers/splitters rather than expensive active filter devices. In this way, after intermediate and destination nodes, lightpaths are dropped and continued, which generates leakage signals in other links and wastes spectrum. Thus, designing efficient resource allocation in FONs by considering the leakage signals and their interfering effects is of utmost importance. On the other hand, a gradual transition from wavelength division multiplexing optical networks to elastic optical networks (EONs) is occurring due to their efficient utilization of spectrum. Furthermore, utilizing the L-band beside the conventional C-band for spectrum assignment offers a wide range of frequency resources. Therefore, in this paper, we propose an integer linear program (ILP) to solve quality of transmission (QoT)-aware tree selection, routing, modulation, and spectrum assignment problems in filterless EONs over the C+L-band. Furthermore, we provide heuristic algorithms to deal with complex large-scale networks. The performance gap of the proposed ILP and heuristic algorithms is evaluated over a small-scale (5-node) network. The results show that the ILP and heuristic algorithms have almost the same performance in terms of spectrum usage and assigned modulation format, and ILP has a slightly higher generalized signal-to-noise-ratio (GSNR) (0.23 dB or 0.8% at optimum launch power). Furthermore, the heuristic algorithms are also examined over a large-scale network (TID region A topology). The results reveal that the GSNR estimation method severely affects the performance in terms of spectrum usage, blocking, and outage. Furthermore, by using the proposed MX5 method, as long as there is a fill margin of approximately 2 dB, there is no outage or blocking over the C+L-band, up to a network throughput of 110 Tbps and conventional C-band transmission with lower throughput (i.e., 40 Tbps). Finally, our extensive numerical results provide a rule of thumb for balancing blocking, outage, spectrum usage, and the number of expensive L-band transponders by selecting the appropriate modulation assignment method.

Fragmentation and ISRS-Aware Survivable Routing, Band, Modulation, and Spectrum Allocation Algorithm in Multi-Band Elastic Optical Networks

“…Exploring the impact of ISRS on QoT estimation is a crucial research issue in C+L-EONs. Several studies focused on the QoT estimation under the influence of NLI jointly with the ISRS, and they demonstrated the significant role played by transmission power and ISRS in multi-band (MB) systems [11][12][13]. D' Amico et al [14] comprehensively consider the ISRS, self-phase modulation (SPM), cross-phase modulation (XPM), and amplified spontaneous emission (ASE) noise in the QoT estimation process and establish the optical signal-to-noise ratio (OSNR) measurement model.…”

“…Sci. 2024, 14, x FOR PEER REVIEW 13 of 1713.2% compared to the LC(L)-DP(C)-EFM algorithm under 3800 Erlang. The superior performance of the proposed algorithm can be attributed to several key factors.…”