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Sep 24, 2010

FCC "final" rules. Cognitive radio or just unlicensed access?

FCC final rules. In the previous post I presented the situation in both the US and Europe regarding the use of unlicensed white space devices in the television band. As it was expected, the FCC released the "final" rules for the cognitive use of TV white spaces in the US (press release, report FCC-10-174).

This solution is based on a database architecture only. That is, the white space devices must have geolocation capabilities and download from a database the occupancy tables while they are not required to perform additional sensing before transmitting. Moreover, as opposed to 2008 rules, the low power devices which could relay only on sensing are banned:
"Eliminating the requirement that TV bands devices that incorporate geo-location and database access must also listen (sense) to detect the signals of TV stations and low power auxiliary service stations (wireless microphones). As part of that change we are also revising and amending the rules in several aspects to reflect use of that method as the only means for determining channel availability. While we are eliminating the sensing requirement for TVBDs, we are encouraging continued development of this capability because we believe it holds promise to further improvements in spectrum efficiency in the TV spectrum in the future and will be a vital tool for providing opportunistic access to other spectrum bands."

Note that the final rules encourage further research in cognitive radio sensing techniques, since this may be useful for other spectrum bands. However the final rules discard the idea of cognitive radios: is it cognitive to download from a database a list of free channels?

On the other hand, wireless microphones, low-power dumb devices that cannot be guaranteed to be registered in the database, will have two channels for exclusive use. Extra channels can be temporarily reserved in the database during special events for the use of these devices.

To finish with, note that the central part of the architecture is still missing. While the FCC already received different proposals for the database architecture, interface and specifications of the database need to be defined yet.

All these issues motivate the use of quotation marks when I write FCC "final" rules.

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Blogger Roberto said...

Fortunately for us working on spectrum sensing, as Gonzalo stresses, the "final" rules still encourage research on this field.
In addition, even if the white space devices themselves are not required to include sensing capabilities, dedicated spectrum monitoring devices can be envisioned in order to "fill in" the blanks of the database entries. These sensors would be strategically deployed by the database managing entity.

October 1, 2010 at 5:24 PM  

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