FCC Commissioner Wants Tests on 5.9GHz to Expand WiFi Access
However, she also faces opposition from automakers that are working on car-to-car communications; the Department of Transportation, which has been supporting that work; and other related research efforts aimed at reducing accidents. The plans for 5.9GHz are part of Rosenworcel’s efforts to expand the use of unlicensed spectrum. One of the problems with such expansion is that the Congressional Budget Office looks at the value of spectrum legislation by considering the likely value to the government that would come from spectrum auctions, she said. Since unlicensed spectrum doesn’t make money for the government, such legislation is assigned a lower value, the commissioner pointed out. This means that because there’s no way to auction this particular unlicensed spectrum, legislation for such use gets a lower priority. Rosenworcel is proposing that the process of spectrum auctions be changed so that for every auction, there’s a cut included for unlicensed use such as WiFi.The experiment uses what she called a "listen-before-talking protocol," which requires the secondary users of the band to make sure that it isn't being used by a service with a higher priority before they transmit anything. This is similar to the CSMA (Carrier Sense Multiple Access) protocol developed for AlohaNet, the wireless precursor to Ethernet. Television white space is another example of the kind of unlicensed use for which Rosenworcel supports tests. There are already two approved database providers that can give local details as to the availability of television white space for use, she said. Because the location of that white space varies according to the locality and which television stations have given up some of the space that they were originally licensed to use, a real-time database is essential. Rosenworcel said that the 600MHz spectrum auctions will include some white space, which will allow a broad availability of this spectrum. “I want channels in every community,” she said. Despite that, it was clear that Rosenworcel considers the unlicensed spectrum, including WiFi, to be extremely important to the overall innovation in wireless. “It’s a place for permissionless innovation,” she said. She noted that WiFi alone had produced more than $140 million in economic activity last year. “We need to watch it grow,” Rosenworcel said, “and we need to protect what we have.”
The 3.5GHz band is the subject of what Rosenworcel called an interesting experiment in which incumbent federal users have the primary use of the frequencies, followed by short-term licensed users and then unlicensed users.