Long Range WiFi Edges Nearer With FCC Decision

A new class of devices able to create WiFi-like connections that span miles rather than meters just jumped significantly closer to market. The Federal Communications Commission (FCC) has made a crucial decision on the rules that will regulate such devices, which will use the "white spaces" between TV channels that were freed up by the analogue switch off.

Although the FCC voted in November 2008 to open up these white spaces, the exact rules governing how they could be used were not decided. Companies of all sizes, ranging from Google to startups, with plans for gadgets and services using white spaces have been waiting since then. Some have spent money lobbying for rules favorable to rapid development of a whole new sector.

A key concern was whether the FCC would stick with a previous suggestion that white spaces devices must constantly listen out for broadcasts from TV stations and also wireless microphones to ensure they wouldn't cause interference. Today the commission decided that this isn't necessary. Instead, the rules will require devices to be capable of knowing their location and using an online database to find out which channels are active in their area.

"The ruling is in the right direction to help us quickly get white spaces devices onto the market, Ranveer Chandra of Microsoft Research who built the world's first white spaces network on the company's Redmond campus, told me.

"Making hardware able to get sensing right is very difficult, particularly for wireless microphones which all have different signals." False positives are a problem when listening for wireless mics, says Chandra, because their signals are so low powered.

Being able to use the software-centric database approach will allow much speedier development compared to the alternative, which would me coming up with new chip designs, he says.

Although Chandra and colleagues experimented with sensing too, the Microsoft network also demonstrates how a database could be used. They developed a cloud-based service to which a device can supply its location and receive back an accurate description of the whitespaces available, based on the position, power and height of nearby transmitters. They also built a website where you can check the white spaces in your area.

The FCC is yet to release the full technical details of the rules, which are expected late today. When these details are released, the real work will start, says Chandra. "Over the next couple of weeks we and others will need to look at that very closely," he says, to work out just what the rules allow for.