Gold in white space

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It is the silver anniversary of the FCC's 1985 adoption of the industrial, scientific and medical rules that provided for a few small islands of unlicensed spectrum in the sea of overly controlled, and frequently very expensive, radio spectrum. The same year, the FCC adopted rules that permitted the use of spread spectrum in these unlicensed bands. Together, these rules enabled all sorts of wireless devices from microwave ovens and remote-controlled toys to cordless phones and, most importantly to us network types, wireless LANs.

Wi-Fi, which was enabled by these rules, has since become a key part of the modern networking world.

The FCC has just gotten one step closer to enabling a far more important chunk of spectrum for unlicensed use and this could have at least as much impact over time, possibly generating many more billions of dollars of business.  A unanimous FCC reaffirmed and tweaked its November 2008 "white spaces" order permitting unlicensed use of unused TV channels. (See "White space and the FCC: a chance to do the right thing".)

In its 1985 spread spectrum order, the FCC noted that "broadcasting groups and some large consumer product manufacturers (RCA, GE and others) suggested that the present level of television service would be seriously degraded if spread spectrum systems were allowed to operate in the television bands." Some things do not change -- broadcasters, this time joined by wireless microphone manufacturers, also raised the same kind of objections to the 2008 order but the FCC stuck to its guns and reaffirmed the order.

On Sept. 23, the FCC adopted a "second memorandum opinion and order" consisting of 59 pages of discussion about various comments the FCC had received about the 2008 order, 19 pages of actual rules and 8 pages of comments by the FCC commissioners.

The FCC did modify or expand some of the details but the basic plan remains the same.

The FCC ensured that two channels would be available for wireless microphones everywhere in the United States . The actual channels will vary from place to place depending on what TV stations are operating locally, so the wireless microphone manufacturers and users will have to be able to configure the microphones. The FCC figures this should be enough for most applications.

The FCC also established rules for a dynamic database that will record the locations and other information about TV stations and non-mobile devices using the newly available spectrum. Concerts and other events that require a lot of wireless microphones will also be able to register in the database for the duration of the event. The FCC is leaving it to industry to actually develop the database services.

Non-mobile devices using the white space spectrum must query the database at least daily to find out what TV channels are in use in a particular area. Such white space devices must avoid using channels already in use by TV stations and the channels adjacent to such channels as well as channels used by wireless microphones at registered events.

Non-mobile white space devices must know where they are located so that they know what part of the database applies to them. They can do this by using geo-sensing (e.g., GPS) functionality or by having the location configured into the device. The devices must also include their location and a device ID in their transmissions so that they can be identified if they cause interference.

The FCC removed a requirement for white space devices to listen to see if a channel was already in use and determined that the database would do a good enough job avoiding interference. The FCC encouraged development of such sensing technology since it would make things more flexible in the future.

This FCC action is a big deal but it will take a number of years for the ramifications to fully develop. It will also likely take a few years for the existing and possible future lawsuits against the action to wend their way through the courts. Wireless LANs continue to grow in importance and this new Wi-Fi on steroids is likely to have a much larger impact down the road.

Disclaimer: Harvard studies steroids but, as far as I know, does not employ them. In any case the above hope is mine and not the university's.

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This story, "Gold in white space" was originally published by Network World.

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