The proliferation of wireless devices such as Wi-Fi laptops or 3G smartphones is causing the available RF spectrum to become increasingly congested while at the same time, large portions of the licensed spectrum are used inefficiently. This discrepancy has brought about a far-reaching paradigm shift in wireless networking, at the heart of which is the need to share the wireless spectrum more efficiently. In my talk, I will give an overview of our "White-Fi" project, in which we have built and deployed the first urban wireless network that operates opportunistically over "White Spaces", i.e., over currently unused TV band spectrum. Our system can "reuse" any available, licensed TV band spectrum, while avoiding interference with primary users of the spectrum. I will give examples of how techniques from distributed computing and optimization can help improve spectrum efficiency, and discuss theoretical results pertaining to the role of wireless networking models. In particular, I will show how even small changes to the assumed network interference model can result in dramatic changes to the achievable network capacity.
Thomas Moscibroda is a Researcher in the Distributed Systems Research Group at Microsoft Research in Redmond. His research interests are in distributed computing, (wireless) networking, and multi-core computer architecture, with a particular focus on algorithmic and theoretical approaches to practical system problems. He obtained his M.Sc. and PhD in Computer Science from ETH Zurich in 2004 and 2006, respectively, and was awarded the ETH Medal for his doctoral thesis. Thomas' research is documented in more than 50 research publications, and he has received Best Paper Awards at several top-tier conferences, including PODC 2004, IPSN 2007, SIGCOMM 2009, NSDI 2009, and ASPLOS 2010. Two of his articles on DRAM scheduling and on-chip networking in multi-core systems were selected as computer architecture top picks by IEEE Micro. In 2009, he was awarded the Microsoft Gold Star Award. Thomas is currently co-leading Microsoft's White-Fi initiative on White Space networking, building the world's first operational urban White Space network. Spectrum regulators from India, China, Brazil, Singapore, and the US (including FCC Chairman Genachowski) have visited the Microsoft Campus in Redmond to see a live demonstration of his research, and his project has been instrumental in the recent FCC decision to open up TV bands for unlicensed use in the United States.