Skip navigation

Spectrum, Spectrum Everywhere: Designing Wireless System for Efficient Sharing

Event Date: March 30, 2015
Speaker: Dr. Krishna Chintalapudi
Speaker Affiliation: Microsoft Research, India
Time: 1:30 p.m.
Location: MSEE 239


Spectrum is a precious public resource like land and water; but it is also, by far, the most heavily regulated. Global wireless data usage is growing exponentially and about 85% of this increase is occurring in less than 5% of the total available spectrum deemed unlicensed. Spectrum regulatory agencies such as FCC (U.S) and OFCOM (U.K) predict a looming spectrum crisis, and efforts are under way to de-regulate spectrum in order to cope with this crisis. Solving this crisis will require fundamental advances in both the design of technologies that allow flexible and efficient spectrum sharing, as well as the development of corresponding policies that are technology and industry friendly. My wireless research over the past several years has primarily focused on the question ``How can spectrum be efficiently shared ?'' Working in the industry, some of my solutions have also made their way into products. I am also currently actively involved in drafting the white space policy for India.

In this talk, I will briefly cover the challenges and opportunities in both technology and policy fronts, focusing primarily on the research opportunities. I will present two examples of my recent research, one demonstrating efficient sharing in time and the other in frequency. The first, WiFi-Nano is a cross-layer   joint PHY-MAC design that leverages self-interference cancellation in order to improve the efficiency of CSMA, the time-sharing mechanism in WiFi, by a factor of 10X.  WiFi-Nano has been implemented, and  its effectiveness demonstrated, on FPGA based software defined radio platforms. The second, IQ-hopping, is a radically novel frequency selection mechanism for the unlicensed spectrum. In IQ hopping devices can quickly self-organize to move away from temporary congestion bottlenecks and spread across uncongested channels within a matter of seconds, relieving the bottlenecks. The key advantage of IQ hopping is that it does not require any communication between devices or any channel scanning mechanisms to measure the congestion in each channel. Not only does IQ-Hopping have provable guarantees with respect to optimality and convergence, but its effectiveness has also been demonstrated on existing off-the-shelf WiFi routers.


Krishna Kant Chintalapudi is a researcher in the Mobility, Networks, and Systems group at Microsoft Research India. Prior to joining Microsoft Research he was a Senior Research Engineer at Bosch Research and Technology Center in Palo Alto, CA, USA. He graduated from the University of Southern California with a PhD in Computer Science. His research interests broadly lie in the area of wireless networking systems. He has worked on various topics such as wireless sensor networks, hard real time industrial wireless control, indoor localization for mobile phones, PHY-MAC cross-layer design, white spaces, wearables and near field communication. He has served in the program committees of several top tier conferences and is currently an associate editor for the IEEE Transactions on Mobile Computing. He is also currently working with regulatory bodies in India to draft a national white space policy.