Spectrum Scavenging

Much of the rural United States is a telecommunications wasteland: residents can tune in only a few broadcast TV channels, and broadband Internet access is prohibitively expensive or nonexistent. But new wireless networking technology – based on the 802.22 standard now being developed by the Institute of Electrical and Electronics Engineers (IEEE)–will enable wireless base stations deployed in rural areas to detect unused TV frequencies and transmit broadband data signals over them directly to modems in homes 40 kilometers or more away.

The base stations and modems will regularly scan the airwaves for vacant TV channels. The system will automatically switch its transmission frequency if, for example, it notices that a new TV station has set up shop. “Our prime directive is to not cause harmful interference to the TV broadcasters,” says Carl Stevenson, the chair of the IEEE group putting together the standard.

IEEE created its 802.22 working group shortly after the Federal Communications Commission proposed giving non-TV broadcasters access to unused frequencies to encourage more efficient use of the radio spectrum. Its goal is to publish the standard by January 2008; compliant products will likely be available soon thereafter. One company, WiFi Wireless of Aliso Viejo, CA, has already announced that later this year it will demonstrate products that operate on TV bands. Such products will have to contend, however, with another emerging wireless networking technology called WiMax, which can beam broadband signals over distances of up to eight kilometers and will reach the market early next year.