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The focus of the latest “Microsoft Research Luminaries” episode is Microsoft researcher Ranveer Chandra, who has found ways to be creative with wireless protocols among other things. Through his work, he has learned it’s possible to reuse unoccupied spectrum, give Xbox games an edge, let mobile devices run longer and provide Internet access to impoverished rural areas.
As Microsoft Research reports, “Radio and TV channels, mobile communications, GPS, and emergency communications are just a few examples of applications that occupy the airwaves. The radio spectrum is a finite resource, but demand for bandwidth is accelerating. As a result, the telecommunications industry is facing what the U.S. Federal Communications Commission (FCC) calls ‘the impending spectrum crunch.’”
Exploring the use of spectral “white spaces” is Microsoft Research’s Mobility and Networking Research Group, and senior researcher Chandra, who has been co-leading the Networking Over White Spaces (KNOWS) project focused on this part of the spectrum.
“Even when a specific chunk of spectrum has been allocated to a specific user, it turns out that, quite often, large portions of that spectrum are unused,” Chandra says. “These empty fragments of spectrum scattered between used frequencies are known as ‘white spaces.’ The FCChas approved experimental licenses for white spaces, and the problem we are trying to solve is: How can you take advantage of white spaces while avoiding interference with the frequency’s primary user?”
In 2009, Chandra co-authored White Spaces Networking with Wi-Fi like Connectivity, which presents the design and implementation of “WhiteFi,” the ﬁrst Wi-Fi-like system constructed atop “white spaces” in UHF frequencies.
The WhiteFi protocol determines the available white spaces within range and transmits using those frequencies. Since the FCC strictly forbids interference with primary users on a channel, the team had to make a performance trade-off between using a wider bandwidth and avoiding interference with adjacent frequencies. In October 2009, Chandra and his colleagues deployed the world’s first operational white-spaces network.
It wasn’t long before Chandra’s research drew the attention of others on Microsoft’s campus, such as the Xbox One team. He helped designed a protocol for the Xbox One controller that prioritizes gaming traffic in a way that gives it a higher chance of getting delivered within a specified period of time – without affecting the experience of other devices in the home.
In another area, Chandra has also been part of a virtual team working on different technologies that reduce the energy consumption of PCs and mobile phones.
And beyond the industry, he sees white spaces as a practical solution for providing Internet connectivity to poor and rural areas of the world.
“The thing about white spaces is that you can cover long distances with UHF TV frequencies,” he explains. “In places such as Africa and India, cellular carriers don’t have the incentive to set up cellular towers for data networking in disadvantaged or rural areas because there aren’t enough users to offset their deployment costs.”
Read more about Chandra and his research at Microsoft Research, where you can also watch the full video interview. (You can also watch it above or on Channel 9.)
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Athima ChansanchaiMicrosoft News Center Staff