Thursday, October 7, 2010

White Space Rules Avoid Pitfalls

The FCC's rules on white-space spectrum seem rather clever to me: The rules adopted today in a unanimous vote by FCC commissioners--a rarity on major policy issues--should be good for all parties. That's hard to achieve. The full rulemaking hasn't been posted yet; an FCC spokesperson told me via email it would posted later today.

White-space devices will have to consult a geolocation database that's regularly updated to avoid stepping on the toes of television broadcasters and other users, notably churches, sports venues, and performing spaces that rely on wireless mics.

To help preserve the use of wireless mics without interference, the FCC will require two channels in the former 7 to 51 (VHF up to UHF) range be reserved in each market for such transmissions. Wireless mic users can petition for additional space, apparently for special events, which means white-space transceivers will have to consult the database on a regular basis.

It's unclear at the moment how devices will grab database info. I could imagine a narrowband repeating transmission on a dedicated otherwise unused channel that would simply dump the local database. White-space devices will certainly require GPS receivers, and computation power and software to figure out the area in which they operate as a distance from other points that have to be offset from use.

The Wi-Fi Alliance put out a press release immediately after, noting that 802.11af is already in progress for adapting WLAN IEEE rules for white-space spectrum and options, and that the alliance already has a plan under way to set a certification programs for such devices.

White-space isn't "Wi-Fi on steroids," but it could be a great enhancement for particular purposes in which Wi-Fi doesn't reach far enough, and a cellular network restricts uses while being overkill and too slow.

There's a potential for competitive wireless networks to emerge over white-space spectrum, but the real-estate issue still intrudes. You might need 1/3 or fewer transmitters per square mile to build a Wi-Space network instead of a Wi-Fi one, but you still have to secure the right to mount gear.

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