Artificial noise saves broadband power

A fairly gratuitous map of broadband speeds in the UK
A fairly gratuitous map of broadband speeds in the UK

A lot of attention has been paid to how server farms are using increasingly huge quantities of power, but apparently broadband systems aren't far behind.

The broadband DSL network consumes about 20 billion kilowatt-hours of energy per year worldwide - that's the equivalent of about 6 per cent of the UK's total electricity bill.

German scientists have come up with a way to allow ADSL systems to use a low power mode that no one has been able to use until now.

Power crazed

Most ADSL2/ADSL2+ systems have a low-power L2 mode that reduces power consumption when internet traffic is light. Unfortunately, when modems in L2 mode become active, they cause interference that slows traffic and can be so great it crashes neighbouring modems, requiring a time-consuming restart.

Scientsists at the Fraunhofer Institute for Communication Systems have now succeeded in using artificial or virtual noise to stabilize DSL connections so that the L2 mode can be used.

The artificial noise simulates typical cable interference so that when a modem connects to the internet, the system registers normal interference even if the device next door is in low-power mode. Although the connection is at a slightly reduced speed, it remains stable when a neighbour goes online.

Network operators could reduce their electricity consumption by several million kilowatt-hours each year, which should (eventually) mean lower broadband prices and more fossil fuels for all of us. Hurrah!

Mark Harris is Senior Research Director at Gartner.