Demand for transatlantic capacity is booming, pushing operators to invest in fibre pair (FP) availability. But as bandwidth demand increases, so does the need for energy to power those networks.
As a responsible operator, we’re constantly asking how can we increase supply and minimise power requirements.
Recently we had a unique opportunity to model potential solutions. Our Aqua Comms AEC-1 system was built in 2015 and stretches from New York to Dublin and onwards to London. Demand for this route saw us light a new FP on the cable this year. That meant we could use the existing FP as a benchmark to model potential improvements in power draw versus capacity volume in the new FP.
We identified three potential ways to reduce power draw: upgrading transponders, reducing regeneration, and optimising backhauls. Here are the savings we estimated.
Upgrading transponders
More efficient transponder technology can significantly optimise the transmission performance cost per bit and sustainability of subsea cables.
We worked with Ciena to assess the performance of our first AEC-1 FP, using the metric of watts per terabit per second (W/Tb/s) across three generations of their coherent optical technologies: WaveLogic 3 (WL3), WaveLogic Ai (WLAi), and WaveLogic 5 Extreme (WL5e).
We ran this assessment using a parameter called “power draw at full fill,” or the estimated kW required if the FP is carrying the maximum amount of traffic for the capacity it generates. With each new generation of coherent technology, we saw significant reductions in power draw — delivering an estimated 67% reduction in W/Tb/s from WL3 to WLAi and a 48% reduction from WLAi to WL5e.
While most FPs are not fully loaded with only one transponder technology, for our newest FP, we have the opportunity to load the whole system with the latest-generation, highest-performing, and most power-efficient transponders — WL5e and WaveLogic 6 Extreme (WL6e). We estimated we could achieve a more than 50% reduction in W/Tb/s over our first AEC-1 FP.
Reducing regeneration
Our first AEC-1 FP uses regeneration at some cable landing stations (CLS), allowing capacity to be restored and amplified over long distances, thus maximising throughput. But regeneration is a double-edged sword from a sustainability perspective. It can improve throughput of a fibre pair but each regeneration increases total system power consumption.
We estimated that by eliminating regeneration at one site, we could achieve additional power savings of over 10%. Unfortunately, we found that we needed the regeneration to achieve maximum throughputs, reach and flexibility in our network. However, other operators may be able to adopt this approach.
Optimising backhauls
Our AEC-1 system designs have always included a fully diverse and protected terrestrial backhaul from our CLS in Kilala to Dublin and London. But having two routes for backhaul not only increases the total cost of acquisition for our customers but also the power draw of the overall system.
We assessed whether our newest AEC-1 FP could offer protected backhaul on an ask-to-provision basis. Two things showed that this was feasible. One route follows a highly protected path over a gas pipeline and has a record of 100% uptime. It’s also increasingly common for subsea customers to purchase routes with triversity (3 routes) or quad-versity (4 routes) between major markets. This means less need for protected backhauls, as their networks are designed to inherently protect themselves.
Our newest FP, therefore, will run just one stable route from the CLS to our main Points-of-Presence (PoPs), saving an additional estimated 56% of the total power draw of our backhaul network in Ireland.
Significant power savings are achievable
The initiatives outlined here result in an estimated 54% overall power consumption reduction in W/Tb/s across the system and 56% in power draw through Ireland compared to the first FP on AEC-1. This highlights the potential across the industry to achieve sustainable improvements, even in infrastructure that is already laying in the ground or (in this case) on the ocean floor.
