Networks face overhaul to reduce energy use

Networks face radical overhaul to cut energy consumption

Mobile, wired and home networks may have to be completely rethought to end an exponential rise in the energy used by communication, according to an industry group.

The Greentouch Consortium was founded a year ago by 13 leading equipment vendors, universities, research labs and operators, with the goal of demonstrating, within five years, a set of technologies that could cut the energy consumption of networks 1,000-fold. It now has 35 members and has launched 25 collaborative research projects, some of which are already bearing fruit.

The consortium has demonstrated a beam-forming cellular antenna that, when using 16 elements, can achieve a 16-fold reduction in the RF energy needed to deliver a set quality of service to a mobile user. It does that by transmitting concentrated beams selectively to users instead of broadcasting across the entire coverage area.

It's part of a wider effort within the mobile equipment industry to reduce RF power consumption by focusing energy more closely on users, through distributed antenna systems and the introduction of femtocells.

“The concept of cellular is changing to more distributed systems,” said Gee Rittenhouse, chairman of the Greentouch Consortium and vice president of Bell Labs Research. “The idea of cellular may not even exist in these new models because you may just have antennas, and where the processing is done is moot. Perhaps all the processing is done in a cloud data centre by a river where it will have good cooling. GreenTouch is really pushing the limits from an architectural perspective.”

Professor Rod Tucker of the University of Melbourne, chair of the consortium's network committee, suggested that cellular networks could also evolve by splitting signalling from the data network. The relatively low-energy signalling traffic would be handled as normal but the data traffic would flow over a separate network, segments of which could be put into a low energy state when not in use.

Claude Monney, a member of the Greentouch executive board and a senior consultant at Swisscom, pointed out that the consortium is trying to use a consistent model of the end-to-end communications chain so that it can spot which approaches are most effective for each of the links, and also to ensure that in optimising one link it does not increase the energy use in another.

The consortium has given each aspect of communications a target for the reduction in energy consumption expected by 2020. For wireline access networks, that target is a 1,600-fold reduction.

“The typical central office hasn't evolved in 100 years,” Monney said. “The wireline access group within Greentouch has a duty to sort this. By using a reference model it is possible to compare topologies and find the most effective one. It will change network topologies to the point where maybe the central office won't exist anymore in future.”

Tucker is also involved in a number of projects concerned with reducing the energy consumption of bringing broadband connection to the home, including better techniques for passive optical networking, fibre networks within the home, sleep modes for home gateway equipment, and the virtualisation of home gateways.

“With a virtual home gateway the home modem becomes a piece of software running on hardware in the telephone exchange. There's great potential for reducing power by putting the home gateway in the telephone exchange,” Tucker said.

Rittenhouse predicted that some of the ideas being developed in Greentouch projects could come to market before the five-year deadline: “There are intermediate points in the development of the technology which can come to market much more rapidly. Some which require a radical transformation will take longer.”

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