By Robert Roe
GreenTouch, a consortium dedicated to improving the energy efficiency of data communications networks, has unveiled new tools, technologies and architectures as part of a five-year study that was completed at the end of June 2015.
The tools developed in this research will enable significant improvements in core, wired residential and enterprise networks, the consortium claims. By employing these energy-efficiency improvements, the net energy consumption of communication networks could be reduced by 98 per cent – equivalent to the greenhouse gas emissions of 5.8 million cars. Originally, the goal had been a thousand-fold efficiency improvement.
Thierry Van Landegem, chairman of GreenTouch highlighted the impressive results achieved by the consortium over the last five years. “With the public release of tools and technologies that industry and academia can use now to design and deploy more energy-efficient communications networks today and in the future. Our work will not only enable a more productive and sustainable future, but will also help many more people to connect with one another,” he said.
The final report from GreenTouch is accompanied by the public release of two new tools available to any organisations interested in creating more efficient networks.
The first tool, GWATT, is a web-based, interactive application that provides a complete view into the entire GreenTouch portfolio of technologies and the energy impact from an end-to-end perspective.
The other tool, called ‘Flexible Power Model’, is an advanced software tool that provides realistic power consumption values for a variety of current and future cellular base station types, configurations and scenarios.
Both GWATT and the Flexible Power Model were announced in May 2013, but were the subject of continued development until the public releases earlier this year.
The background research for GWATT can be found at the end of the GreenTouch report and the literature for the Flexible Power Model can be found on the consortium’s website www.greentouch.org.
GreenTouch, was formed in 2010, driven by the vision of Bell Labs, the industrial research arm of Alcatel-Lucent, and includes more than 40 academic institutions and member companies. Its aim was to determine how to support the growth of communications networks in a sustainable and economically viable way.
At that time, the consortium determined that reduced energy consumption and increased energy efficiency can enable the practical and greater use of renewable energy. This allows the networks to scale in a more sustainable way – increasing traffic without scaling of energy consumption proportionally.
The global information and communications technology (ICT) industry will account for about 1.97 per cent of worldwide carbon emissions in 2030, according to a report from Global e-Sustainability Initiative (GeSI) entitled SMARTer2030. Although less than the predicted 2.3 per cent of carbon emissions in 2020, this still represents a significant amount of money.
GreenTouch has highlighted a number of areas where an effort to reduce energy consumption of communications networks can provide significant savings. The greatest energy savings could be achieved in the mobile access networks – using an optimised architecture the consortium expects an improvement of more than a factor of 10,000 in relation to the 2010 reference scenario. Traffic in the mobile access network is predicted to increase 89-fold between 2010 and 2020. Even with the much higher traffic load anticipated in 2020, the network energy consumption can be lowered by a factor of 110 due to the significant improvement in network energy efficiency.
In residential fixed access networks, a 254-fold increase in energy efficiency will be possible using a combination of several techniques: the Cascaded Bit-interleaved PON (Bi-PON) architecture, the use of virtual home gateways, an adaptive power mode for optical transceivers, and the introduction of a ‘sleep mode’ for electronic components in the network.
First introduced in March 2012, Bi-PON is a more disruptive concept where a new protocol allows optical network units (ONUs) to recognise and only process the bits intended for them – in contrast to today’s broadcast-and-select based PON system, where every ONU on the PON must perform intensive processing on all of the data that is broadcast from the optical line terminal (OLT) in the central office. Further processing is done at the lower user rate instead of the aggregate line rate, which results in more than an order of magnitude power savings.
The report also notes that there are a number of techniques that yield substantial energy savings in core networks. Improved network components, notably the optics in routers and transponders, will make a significant contribution, as well as the use of mixed line rates (MLR) by selecting the appropriate combination of wavelengths and line rates for minimal energy consumption.
Other techniques include intelligent management of protection resources, sleep modes for components, optimisation of the network physical topology through the allocation of direct links between nodes, the use of optimised distributed clouds for content distribution, content caching, and network equipment virtualisation.
The report states that “routers are expected to improve by 39x due to the combination of GreenTouch and business as usual improvements, while transponders and regenerators are expected to improve by 6x.”
However the report did concede that some components such as, erbium-doped fibre amplifiers (EDFAs), would only improve according to Moore’s Law on the part of the control electronics without any significant improvements in the optics power consumption.
The combination of these techniques will provide a combined 316x improvement in the energy efficiency of core networks compared to the 2010 reference scenario defined by GreenTouch.
“This profound result demonstrates that we can support the predicted traffic growth in future networks while at the same time significantly reducing the total energy consumption of the networks. Increased traffic and increased performance do not have to come at the expense of increased energy consumption,” the report concludes.