A just-published standard for using the "white spaces" between TV channels could offer as much as 22M bps (bits per second) over distances as great as 100 kilometers (62 miles).
The Institute of Electrical and Electronics Engineers announced on Wednesday that it has published the IEEE 802.22 standard, which defines the unlicensed use of frequencies between TV channels in the VHF and UHF bands. The IEEE 802.22 Working Group began its standards effort after the U.S. Federal Communications Commission started exploring the use of these frequencies by unlicensed devices. But the group said its standard could be used around the world, especially in rural areas and developing countries where there tend to be more vacant TV channels.
Microsoft, Google and other big technology players strongly pushed for use of the white spaces in the U.S., going up against strong opposition by TV broadcasters who said unlicensed devices in those bands would interfere with their signals. IEEE 802.22 will not interfere with TV broadcasts, because it incorporates several features to prevent interference, including the use of databases of incumbent spectrum users, the IEEE said in a press release.
By using long-reach frequencies like those that transmit TV across metropolitan areas through walls, IEEE 802.22 could allow service providers to deliver mobile data services with fewer transmitters than ordinary cellular systems. This makes the standard promising for areas that are unserved or underserved, the IEEE said. As with Wi-Fi, use of white spaces won't require anyone to pay a licensing fee.
The FCC approved the use of unlicensed gear in the white spaces in 2008, and last September it eased the regulations on these uses by removing the need for "spectrum sensing" technology. Devices will still need to have access to databases of what frequencies are being used nearby and be equipped with cognitive radio technology so they can change frequencies when necessary. The IEEE standard incorporates those features.
Consumers have just begun to receive Internet access over white-spaces spectrum, but over the next few years, the technology may be used widely for government applications, consumer services and backhaul from Wi-Fi networks, said Farpoint Group analyst Craig Mathias. TV uses channels in the same general band all over the world, and many countries have adopted white-spaces rules, so there may eventually be a global market for devices that use the technology, he said. High-volume production tends to bring low prices for equipment.
However, white spaces will never be used as widely as Wi-Fi or cellular, Mathias said. He expects its use to be focused on rural and underserved areas.
Even with its long range, the technology might be hard for service providers to use, said Gartner analyst Ken Dulaney.
"If this applies to rural areas, which I think is a target, you have problems with low density and thus have to price it high or lose money," he said.
