Networking Bene ts of Optimized Regenerator Placement and Hybrid Fiber Amplifi cation

Abstract

The continuous growth of IP tra c is pushing telecom operators to carefully consider core network upgrades. Operators concern is to cope tra c increase, maximizing return over investments on already installed equipment. One of the simplest solutions to accommodate future core-network tra c is the extensive use of optical-electrical-optical (OEO) lightpath regenerators in nodes, relying on a mostly translucent network con guration. Besides reducing network exibility, extensive OEOs usage is limited mainly by their power consumption, size and cost; hence, operators are looking for physical layer solutions alternative to them. The recent assessments of the capacity improvement granted by the upgrading of optical ampli ers, in this work we analyze if the selective upgrade of line ampli ers can be helpful in reducing the number of OEOs needed to sustain an existing tra c in two di erent network scenarios. Hybrid ampli cations schemes enable a distributed gain that decreases the equivalent noise gure (ENF) of the ampli ers and consequently the generated ampli ed spontaneous emission (ASE) noise, improving Quality-of- Transmission (QoT). Such improvement is colorless, since it a ects the entire WDM channel comb. Thus, placing Hybrid Fiber Ampli cation (HFA) on network spans can bring global bene ts to the allocated LPs and consequently to networking performance. Even if OEOs permit to completely reset propagation impairments by breaking LP transparency, they bring local bene ts, since they operate on a per-channel basis. Understanding the tradeo s between these two techniques is therefore fundamental in the assessment of networking merit of physical layer technologies, to properly drive future core-network upgrades. We focus on Pan-European and USNET topologies analyzing the impact of selectively introducing HFA with di erent pumping schemes and ENFs. We show that for USNET topology, HFA with 3 dB ENF, allows to completely remove the OEOs needed to sustain a uniform any-to-any tra c matrix with 200Gbps per connection, whereas for the Pan-European topology, adopting HFA with 0 dB ENF permits to save up to 75%of required OEOs.