WASHINGTON-The Department of Defense and Federal Communications Commission say they are cautiously optimistic about finally achieving a technical solution that could enable an explosion of new Wi-Fi connections in the 5 GHz band without compromising military radar.
Government and industry representatives plan to meet Tuesday to discuss the DoD’s preliminary report analyzing bench tests and field trials of Wi-Fi gear armed with “Dynamic Frequency Selection” technology. DFS monitors the airwaves to detect and avoid transmitting on any 5 GHz channel occupied by the military.
“We remain encouraged by progress to date,” said Badri Younes, director of spectrum management at the DoD. “The results were promising.”
Though the Pentagon and FCC say they are encouraged by 5 GHz Wi-Fi DFS experiments using equipment from Atheros Communications, Cisco Systems Inc. and Motorola Inc., the results have not been perfect across the board.
Indeed, according to sources, Motorola did not fare well in bench tests or field trials. That testing is not the end of the process, however.
“Many of these things have to be evaluated with respect to impacted [DoD] programs,” said Younes.
On several levels, a lot is riding on the outcome of efforts to perfect Wi-Fi DFS technology.
First, any solution must be free of chance disruptions to Pentagon radar systems. Anything less is a deal breaker.
Industry, military and government officials have been working on a fix for three years after the National Telecommunications and Information Administration announced an agreement with the Pentagon to designate hundreds of megahertz for Wi-Fi so long as short-range wireless Internet connections did not disrupt radar. The U.S. government then went on to get international agreements to expand Wi-Fi at 5 GHz at the 2003 World Radiocommunication Conference.
Refining the DFS feature has been elusive, with progress attained in fits and starts. Initially, U.S. officials believed they had the military radar interference problem licked. Then they realized a serious glitch. While DFS could identify and dodge military radar, it could not distinguish radar from other sources of radio-frequency energy-including Wi-Fi. As a result, Wi-Fi units with DFS programming would unnecessarily forgo otherwise usable radio channels, making for inefficient use of the spectrum.
The DoD’s concerns about 5 GHz Wi-Fi interference may have been underscored after reports surfaced earlier this years that Wi-Fi devices were responsible for disrupting radar at Eglin Air Force Base in Florida. However, there was speculation the Wi-Fi culprit may have been operating at higher-than-normal power levels.
Despite setbacks, quiet progress was made by NTIA engineers and spectrum managers at the FCC and DoD.
But the 5 GHz Wi-Fi snafu has broader implications beyond military readiness, especially for U.S. spectrum policy and the growing $5 billion Wi-Fi market (infrastructure and services).
A solution free and clear of complications would permanently free up an additional 255 megahertz in the 5 GHz band for mass market Wi-Fi consumption-good news for chipmakers, Wi-Fi vendors, personal computer makers and others.
The FCC, with the Pentagon’s consent, said in January that Wi-Fi gadgets without DFS could be sold and imported until January. The rule clarification reflected the two agencies’ acknowledgment that introducing one year’s worth of new Wi-Fi devices-without DFS-into the market would not pose a threat to military radar. The January window is about to close, however.
In reality, there is more spectrum at stake than the 255 megahertz the FCC allocated for Wi-Fi in November 2003. The DFS fix is needed to cover operations in another 100 megahertz previously earmarked and currently used for Wi-Fi links at 5 GHz.
Another benefit of a sustainable 5 GHz Wi-Fi DFS solution would be to showcase successful spectrum sharing between government and non-government users on a scale far grander than NTIA’s planned spectrum-sharing pilot program.
There are global commerce ramifications as well. When the FCC released the 255 megahertz for 5 GHz Wi-Fi three years ago, the agency stated: “This action will also harmonize the spectrum available for these devices throughout the world, enabling manufacturers to reduce product development costs by allowing the same products to be used in many parts of the world.” RCR
