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Wireless Networks Look Ripe for Energy Savings

A few tweaks could save massive amounts of energy in wireless networks, but the new technologies and business practices that look most promising will take some time to make their way into the marketplace. Still, the potential is strong, according to a report released Tuesday by the GreenTouch Consortium, a research effort funded by more than 50 companies to explore ways of getting all kinds of communications networks to do more work per kilowatt of power. (See GreenTouch IDs Telco Energy Savings.) "It's a huge task," says Thierry Van Landegem, chairman of GreenTouch and vice president of global operations at Alcatel-Lucent, but the consortium reckons it's feasible to improve the overall energy efficiency of the world's communications infrastructure by as much as 90 percent by 2020 -- even taking into account bit-traffic growing by a projected factor of 88 in mobile networks and 10 in the core network. The challenge will be getting components and systems makers to actually design products incorporating GreenTouch's ideas. In wireless, says Van Landegem, something as simple as an "off" switch looks like it could help save a great deal of energy. So to speak. Today's base stations are always on, he explains, sucking watts even when there's no traffic in the air. Even when idle, a typical base station may use 70 to 80 percent of its peak power. So, why not make energy usage more proportional to traffic load? Intelligent control mechanisms could figure out when to bring down power and by how much. Bandwidth could be altered and amplifiers adjusted with some degree of granularity. A base station might even use past experience to learn when to shed power. Trouble is, today's hardware is not yet capable of responding to such commands, Van Landegem says. Another promising change would be to tighten the transmission radius of wireless cells, thereby lowering their power considerably. Today's macro cells operate at distances of 1 to 4km, but using small cells, operating at 200 to 300 meters and deployed in greater numbers, could be a big help. It's simply a matter of physics, as the transmission power required rises by the fourth power of the radius that needs to be covered. So: smaller cells, fewer watts. Still more gains in wireless could be achieved through sharing of infrastructure. Today, each major operator deploys its own base stations, but by virtualizing much of that gear's functionality and sharing it between operators, utilization rates could be greatly improved. "Not everybody would have to overbuild," says Thierry Klein, chair of the GreenTouch technical committee and head of green research at Bell Labs/Alcatel-Lucent. "This would be a big step forward for the U.S." (The U.K. is at the forefront of infrastructure sharing, Klein notes, but there, it's done mainly to share costs in sparsely-populated rural regions, not to save energy.) These and the other technology improvements that GreenTouch is cooking up will not be realized without investment by member companies. GreenTouch has no plans to design or even propose products; it only seeks to "create awareness" and "accelerate the technology cycle." The group plans to release in June a more complete report on future energy-saving communications technologies. This week, consortium members are meeting in Shanghai, in person instead of via energy-efficient videoconferencing. For more — John Verity, contributing editor, special to Light Reading
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