Government, industry reach accord on WLANs

-- Paul Roberts

The U.S. government and the wireless technology industry have resolved a dispute that threatened to curtail the deployment of the next generation of wireless networking and communications technology that uses the 802.11a standard.

As part of an agreement reached Friday, the government will open 255MHz in the middle of the 5GHz spectrum to unlicensed use, creating 11 additional channels on which 802.11a wireless devices can operate, according to Rich Redelfs, CEO and president of Atheros Communications, which lobbied the government for changes in the spectrum rules.

The dispute between the wireless industry and the government, represented by the Commerce Department's National Telecommunications and Information Administration (NTIA), arose over concerns voiced by the U.S. Department of Defense ( DoD ) that devices using the 802.11a standard would interfere with military radars that also use that spectrum.

The NTIA couldn't be reached immediately for comment.

As opposed to devices that use the 802.11b standard and transfer data at up to 11M bps, 802.11a devices can exchange data at faster rates, up to 54M bps, but have a more limited range.

With the rapid adoption of wireless technology that uses the 802.11a standard, especially wireless Ethernet devices, the DOD was concerned that the use of radar in future military operations would be hampered by interference from civilian wireless devices operating in the 5GHz range.

The debate between the NTIA and industry hinged on the use of dynamic frequency selection (DFS) technology, which allows 802.11a wireless devices to detect the presence of radar beams on a particular channel in the 5GHz range and automatically switch to a different channel.

The DOD wanted to increase the sensitivity of 802.11a wireless devices that use the DFS technology, while the wireless industry was worried that too much sensitivity to radar devices would make their technology unreliable.

With the addition of 11 new, non-interfering channels to 13 existing channels in the 5GHz range, however, there will be more breathing room for both radar and wireless devices that use DFS, reducing the likelihood of conflicts, Redelfs said.

The agreement, which will be announced by the NTIA on Monday, will also allow the U.S. to present a united front in the upcoming World Radio Conference in Geneva, Switzerland in June, when representatives from different countries will meet to agree on spectrum allowances and rules, according to Redelfs.

Without an agreement, the U.S. might have had a tough time getting backing for its own plan, especially because the same 255 MHz band is already open to unlicensed use in Europe, Redelfs said.