Whither white spaces? If you believe the hype, last week's decision by the U.S.'s Federal Communications Commission to make the so-called white space spectrum available for wireless broadband services could prove to be a seminal moment in the development of the mobile Internet.

The white spaces are the "first significant block of spectrum made available for unlicensed use in more than 20 years" according to the FCC, which bills the gaps between TV channels as being able to support "super Wi-Fi", among other services. The FCC says that Dell, Google, Microsoft, Motorola, and Nokia are among the companies supporting the unlicensed release of the white space spectrum, which could, in theory, be used to provide a low-cost form of wireless broadband in competition with services in licensed spectrum.

The FCC believes that the white spaces spectrum, which falls in low-frequency bands below 700MHz, will enable the creation of Wi-Fi hotspots with "extended range, fewer dead spots, and improved individual speeds as a result of reduced congestion on existing networks." As the FCC says, transmissions in low-frequency spectrum travel long distances, but the downside of these bands is their relatively low capacity – the "super Wi-Fi" hotspots probably won't be able to provide high-speed broadband to large numbers of users simultaneously.

Wi-Fi on crutches?

The actual white space available in any given location will vary according to which TV channels are broadcast locally, so devices will be required to figure out where they are and then lock in on the relevant white space. Some commentators have argued that the white spaces will be very narrow in most urban areas, providing for channels of only 6 MHz, rather than the 20 MHz channels normally used by Wi-Fi. That will severely limit throughput speeds and capacity, which is one of the reasons that Charles Jackson, writing on High Tech Forum, characterises Wi-Fi in the white spaces as "Wi-Fi on crutches."

There are also other reasons to be sceptical. White spaces devices could be expensive, partly because they have to be able to determine their location and then channel hop and partly because they won't be able to tap the economies of scale inherent in a global ecosystem – the FCC claims the U.S. will be the first country to release the spectrum and other countries may not follow suit.

In reality, Wi-Fi in the white spaces probably won't be on steroids or crutches. It seems like white space hotspots will provide better coverage and in-building penetration than Wi-Fi hotspots at 2.4GHz, but significantly lower transmission speeds. These qualities could give the white spaces a significant role in places where Wi-Fi or mobile broadband coverage is patchy. But, for broadband Internet service providers, white spaces Wi-Fi will be a fall-back option rather a first-choice.

Perhaps the biggest opportunity for white spaces Wi-Fi could be in the machine-to-machine market where environmental sensors, smart meters and other monitoring devices are required to transmit small volumes of data at regular intervals.

The FCC says its "experimental licenses" for white spaces spectrum are being used to provide broadband access to a remote elementary school in Claudeville, Virginia, for traffic management and water quality monitoring in Wilmington, North Carolina, to enable a smart grid in Plumas County, California and for telemedicine in Logan, Ohio. In other words, mostly low-bandwidth applications in hard-to-reach places.