Full Duplex Wireless
Phil Levis, Stanford University
Wireless networking traditionally assumes that radios are half-duplex.
On a given frequency, a half-duplex radio can either transmit or
receive, but not both at the same time. I present recent results
demonstrating that a full-duplex radio -- a radio that can receive and
transmit simultaneously on the same frequency -- can be built using
commodity, off-the-shelf components. I discuss some of the possible
implications of full duplex, including solving some long-standing
problems in wireless, such as the hidden terminal problem, signal
boosters, and access point fairness. I examine the design space for full
duplex radios, describing the corresponding tradeoffs. Full duplex has
the potential to revolutionize a large number of wireless systems: I'll
conclude with current strengths and limitations of the technology to try
to shed some light on where I think it might be most and least successful.
The talk is intended for a CS audience; it does not assume any RF theory
background, just a high school level understanding of the physics and
mathematics of sine waves.
Philip Levis is an Associate Professor of Computer Science and
Electrical Engineering at Stanford University. He received his Sc.B.
from Brown University in 1999, his M.S. from the University of Colorado
at Boulder in 2001, and his Ph.D. from UC Berkeley in 2005. In 2008 he
received an NSF CAREER award and a Microsoft Research New Faculty
Fellowship. He researches the design and implementation of networked
systems that interact with the world, including operating systems and
protocols for embedded wireless devices, wireless mesh protocols,
network infrastructure for virtual worlds, and energy efficient
computing. The results of his research, including the TinyOS operating
system, nesC language, Trickle algorithm, and the collection tree
protocol (CTP), have been adopted by tens of thousands of users and
researchers worldwide. He's authored a few Internet standards based on
his work. He really likes excellent engineering and has a
self-destructive aversion to low-hanging fruit.