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Type of Talk: UTCS Colloquium/LASR

Speaker/Affiliation: Rohan

Murty/ Harvard University

Date/Time: Monday, November 23, 11:00 am

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Location: ACES 6.304

Host: Lili Qiu

Talk Title: "WhiteFi: Whi

te Space Networking with Wi-Fi like Connectivity"

Talk Abstract:
Thu

s far, the UHF spectrum has been primarily used by incumbents licensed use

rs) such as TV transmitters and wireless microphones. The unused portions o

f this spectrum, popularly referred to as ''white spaces'', represent a n

ew frontier for wireless networks, offering the potential for substantial

bandwidth and long transmission ranges. The recent analog to digital TV tra

nsition in the US further enhanced the availability of these white spaces.

On November 4, 2008, the FCC issued a historic ruling permitting the use

of unlicensed devices in these white spaces while ensuring non-interference
with TVs and wireless microphones. But how do we actually build wireless n

etworks that use this spectrum without interfering with the licensed owners

?

In my talk I will address the challenges faced when networking over

these UHF white spaces. I will first make the case so as to why networking

over the white spaces is fundamentally different from conventional Wi-Fi,

namely, spectrum fragmentation, spatial variation, and temporal variatio

n of spectrum. I will then present the design and implementation of WhiteFi

, the first Wi-Fi like system built to use these UHF white spaces that add

resses these differences. WhiteFi incorporates a new adaptive spectrum assi

gnment algorithm to handle spectrum variation and fragmentation, and propo

ses a low overhead protocol to handle temporal variation. WhiteFi builds on
a simple technique, called SIFT, that reduces the time to detect transmi

ssions in variable channel width systems by analyzing raw signals in the ti

me domain. I will also present results from our prototype hardware.

Sp

eaker Bio:
Rohan Murty is a 5th year PhD candidate at Harvard University

where he is advised by Prof. Matt Welsh. His research interests include wir

eless networks, scalable content distribution systems, and sensor network

s. His recent work has focused on white spaces-based wireless networks, ex

tensible architectures to manage enterprise Wi-Fi, and exploring the impac

t of density in Wi-Fi networks on overall network capacity. He is currently
supported by a Microsoft Research Fellowship. He completed his B.S. from C

ornell University in 2005.