Cost analysis of ultrawideband transmission in optical networks

Abstract

We examine the cost associated with increasing traffic on a reference transport network for both single- and multiband systems, with a total transmission bandwidth ranging from 4.8 to 20 THz (S2 + S1 + C + L-band, where S2 and S1 are the two halves of the S-band). The number and cost of amplifiers, transceivers, and fibers are considered. To ensure stable transmission power and simplified network management, we take noise loading into account. The optimal combination of transmission bands—for each system—is evaluated based on the maximization of the capacity calculated from the minimum per-band generalized signal-to-noise ratio of each band. The results reveal that, despite the lower spectral efficiency due to the higher fiber attenuation and band MUX/DEMUX insertion losses, multiband systems can effectively reduce the number of fibers needed, thus postponing the deployment of new fibers. The most cost-effective solution depends on the fiber and S-band amplifier costs and the forecast of the required network capacity. When additional fibers are freely available or fiber costs are minimal, employing a C-band-only system proves to be the most economical choice. As fiber costs increase, additional bands gradually become more appealing, progressing from the C-band-only to the C + L-band, and then to the addition of half of the S-band (S1 + C + L-band) or the whole S-band (S2 + S1 + C + L). Furthermore, multiband transmission systems are more attractive when considering higher traffic loads. We also propose an optimal order of deployment of transmission bands in a pay-as-you-grow approach. The corresponding cost evolution demonstrates that this approach is a viable solution to mitigate excessive costs during the initial stages of a network operation, even though it leads to an increased number of fibers and transceivers used before all transmission bands are enabled. Additionally, we show that the S1- and S2-bands have worse optical performance, making them more suitable for shorter lightpaths. Consequently, operating the S-band in single-hop links and simplifying the add-drop multiplexer architecture could be beneficial.