C+L+S-Band Optical Network Design Exploiting Amplifier Site Upgrade Strategies

It is possible to increase the available capacity of an optical network without any new fiber deployment, by exploiting transmission over the spectral bands beyond the C-band. Due to the characteristics of fiber and devices characteristics required to work with this wide-band transmission, as well as the physical effects raised by it, channels using spectral bands beyond C + L, e.g., in the S-band, can present comparatively poor quality of transmission (QoT), reducing the spectral efficiency. One way to deal with this problem is to install new amplification sites (ASs), decreasing the span length, improving the overall QoT and potentially allowing the use of more efficient modulation formats. In order to maintain the costs of a multi-band network upgrade reasonable, the spans which will receive a new AS need to be properly selected to maximize the overall delivered capacity without relying on an excessive number of new ASs. In this work, we investigate a C+L+S network design that takes advantage of the selective amplifier site upgrade. The results of the network simulation show that the proposed approach leads to a considerable increase in capacity while reducing the number of interfaces required for a fixed number of amplifiers and new ASs.