Researchers from the Microsoft have developed a protocol. The company claims that, this could be the foundation for products meeting the requirements of Federal Communications Commission for avoiding interference while using unlicensed white space spectrum. The researchers had presented this brilliant idea last week at ACM SIGCOMM 2009, a communications conference held in Barcelona, according to an article which published in Massachusetts Institute of Technology’s review website. “White space” spectrum is the unused wireless spectrum, which lies between analog TV channels. Much of this spectrum operates at very lower frequencies,and it can travel longer distances than the unlicensed frequencies used in Wi-Fi communication. Most of the Wi-Fi devices operate at a frequency of 2.4 G Hz.
White space spectrum lying between analog TV channels 21 and 51 are operating in the 512 megahertz and 698 megahertz range. Signal tends to travel longer distances at slower speeds when transmitted over lower frequencies while signals tend to be faster over shorter distances, transmitted at higher frequencies.
Technology companies, like Google, Microsoft, Motorola, and Dell are lobbying the FCC to open this spectrum for unlicensed use. They hope that this spectrum can be used to augment the existing wireless services. Eventually this spectrum can be used to create wireless broadband services.
Wireless microphone companies and TV broadcasters are opposing the use of this spectrum, because they think it will interfere their services.
The FCC in November,2009 agreed to open up the unused broadcast TV spectrum for unlicensed use after a series of prototype tests. So the commission put a set of strict guidelines. This is to ensure that devices using the unlicensed spectrum will not interfere with other devices using the same unlicensed spectrum and existing TV broadcasters.
Microsoft calls the set of protocols it designed as White-Fi, and they claims they will be able to avoid interference and will make best use of the spectrum. One of the major challenges with avoiding interference is the introduction of new devices using the same frequency into the network at any time. Just like turning a wireless microphone on and off. Even tiniest bit of interference may cause interference problems.
Microsoft designed White-Fi protocol to avoid this problem. Each device will find available frequencies, measure the spectrum conditions around it and keeps searching for interference. If interference occurs, it will move to a different sliver of spectrum at any time. It works by connecting the device to the available white space frequency. At the same time, it will maintain a backup radio frequency channel. This signal could switch to the backup frequency if another device using the same frequency comes into its range. I’m sure that as this services and technology find new horizons, carriers will definitely contemplate incorporating white space spectrum into new services