The white spaces effort so far

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The white spaces effort so far

By CAROLINE GABRIEL

Published: 7 April, 2008

READ MORE: Spectrum

In October 2006, the FCC gave the green light to technologies to use unused TV frequencies, provided they could demonstrate non-interference. Just three months later, the Microsoft coalition had outlined its technology and sent a statement of support to the FCC, and in February 2007 the specifications for the machine were sent for testing to the regulator's Office of Engineering and Technology (OET). A drawing of the cognitive radio's test set-up, included in the filing, indicated that it would be able to access white space signals for a UHF radio, a CR scanner, and a laptop computer attached to network processor through an Ethernet interface. Users would at first specify a TV channel for the device to pick up. The machine would search for other signals if that one was already taken.

In its January 2007 statement, the White Spaces Coalition asked the FCC to:

Authorize the use of 'spectrum sensing' rather than geo-location technology (the main technique used in existing solutions) to find white space. The group argues that spectrum sensors do not need databases of available channels to function, and so are more flexible.

Recommend that such devices check whether the channel is being used by a TV broadcaster once a minute, rather than every 10 seconds as recommended by the Commission's first proposal.

Avoid any delays in deployment of unlicensed devices. The FCC has provisionally OK-ed white space detecting devices to go on sale on February 2009, the day after all analog TV signals are due to cease.

Two Microsoft attempts have failed and so far the FCC has not approved any device. It is also considering an alternative proposal, led by Sprint Nextel and other cellcos, to allocate the spectrum for mobile backhaul.

Meanwhile, freeing up the white spaces faces opposition not only from broadcasters but also from the cellular operators, whose representative body the CTIA recently said the white spaces were "worth money" and should not be given away freely - a stance Google denounced as "greedy". Though the potential threat to cellcos from Wi-Fi mesh did not really materialize, the operators are well aware that in some scenarios, especially in rural areas, this new spectrum option could put powerful weapons in the hands of disruptive players, with low or zero cost of entry.