Wi-Fi and WiMAX will coexist and become increasingly complementary technologies for their respective applications. Wi-Fi technology was designed and optimized for Local Area Networks (LAN), whereas WiMAX was designed and optimized for Metropolitan Area Networks (MAN). WiMAX typically is not thought of as a replacement for Wi-Fi. Rather, WiMAX complements Wi-Fi by extending its reach and providing a "Wi-Fi like" user experience on a larger geographical scale. In the near future, it is expected that both 802.16 and 802.11 will be widely available in end user devices from laptops to PDAs, as both will deliver wireless connectivity directly to the end user - at home, in the office and on the move.
The vast majority of viable spectrum in the United States simply goes unused, or else is grossly underutilized. The U.S. typically uses only about five percent of one of its most precious resources. Unlike other natural resources, there is no benefit to allowing this spectrum to lie fallow. The airwaves can provide huge economic and social gains if used more efficiently, as seen today with the relatively tiny slices utilized by mobile phones and WiFi services.
In an effort to free up spectrum for public safety use, Congress has ordered TV broadcasters to shift their signals from analog to digital by February 2009. When this happens, there will be open and unlicensed spectrum between the digital channels, or white spaces, that companies like Google and Microsoft want to use for wireless broadband service.
The unique qualities of the TV white spaceunused spectrum, large amounts of bandwidth, and excellent propagation characteristics (they travel long distances and can penetrate thick walls)offer an opportunity to provide ubiquitous wireless broadband access to all Americans. In particular, this spectrum can provide robust infrastructure to serve the needs of under-serviced rural areas, as well as first responders and others in the public safety community. Moreover, use of this spectrum will enable much needed competition to the incumbent broadband service providers.
This is a large amount of untapped spectrum and you've got people in Silicon Valley and lots of smart entrepreneurs just itching to find ways to use it.
But, broadcasters insist that use of these white spaces for broadband service will result in reduced-quality digital TV viewing. Unlike on traditional analog TV, where interference causes static or fuzziness, digital pictures can freeze or be lost entirely if another signal is broadcast on or near the same channel.
The Wireless Innovation Alliance, which includes Google, Microsoft, HP and Dell, thinks it is possible to produce a device that detects and avoids broadcast programming so it will not interfere with existing signals. Such technology is already being used by the U.S. military. FCC officials are intrigued by the possibilities and are testing sample devices to see if they could sense and avoid TV signals. But, the results have been mixed.
Broadcasters are skeptical, and the makers of wireless microphones for sporting events, concerts and churches, which also use this unlicensed spectrum, say the technology could put their productions at risk. They support auctioning off those fallow airwaves and making them licensed in order to protect against interference.
There are many ways to safely and reliably protect digital TVs and wireless microphones, not all of which require spectrum sensing. Last fall, Motorola submitted a proposal that relies on a combination of geo-location (to protect broadcast TV) and beacons (to protect wireless microphones). Google believes both concepts, along with a safe harbor approach, should be seriously considered for incorporation into the FCCs service requirements for the spectrum.
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