Effect of reduced link margins on C + L band elastic optical networks

Network traffic is growing exponentially, which has increased the onus on network operators to expand their network spectral resources beyond the C band. This work explores the effect of operating at a reduced link margin (LM) over the combined C and L bands. For this purpose, we utilize a lightpath optical signal-to-noise ratio (OSNR) estimation model that considers nonlinear interference due to inter-channel stimulated Raman scattering and amplified spontaneous emission noise generated by in-line amplifiers while predicting the OSNR. This model is utilized to account for the benefits of operating at reduced LM in the BT-UK, Pan Europe, and USA-NSFNET networks. Our results indicate that significant gains in capacity can be achieved by operating at low margins across all the networks. Furthermore, it is concluded that the launch power of network lightpaths should be optimized based upon the network size and operating LM.