COLLOQUIUM
Department of Computer Science and Engineering
University of South Carolina
 
Utilizing Beamforming Antennas for Wireless Multihop Networks

Romit Roy Choudhuri

Department of Computer Science
University of Illinois

Date: February 17, 2006
Time: 1430-1530
Place: Swearingen 1C01 (Amoco Hall)

Abstract

Wireless multihop networks are gaining popularity in applications such
as mesh networks, wireless backbones, and sensor networks. Typically,
communication protocols designed for such networks have explicitly or
implicitly assumed an omnidirectional antenna at the radio layer. With
recent progress in signal processing and antenna technologies, smart
beamforming antennas have become feasible at cheaper prices, making
them an attractive replacement to omnidirectional antennas. With
beamforming antennas, the ability to guide RF energy in desired
directions can lead to higher spatial reuse of the channel. Also, the
higher communication range of beamforming antennas can be exploited to
achieve stronger network connectivity, and to obtain fewer hop
routes. However, existing protocols considered suitable for
omnidirectional antennas are incapable of achieving these benefits. We
have identified several weaknesses in these protocols, including new
kinds of hidden terminal problems, "deafness", "MAC-layer capture",
etc., that together degrade overall network performance. We have
addressed each of these weaknesses systematically, and developed a
better understanding of the theoretical improvements in capacity that
can be achieved with beamforming antennas. Based on the insights, we
have designed medium access control (MAC) and routing protocols to
fully exploit the benefits of beamforming. We have demonstrated part
of our solutions on a prototype testbed, equipped with electronically
steerable antennas.  
This presentation will discuss our work on
exploiting current and future smart-antenna systems in wireless
multihop networks. I will describe the new challenges that arise with
beamforming, and focus on the design, analysis, and evaluation of new
MAC and routing protocols. I will also summarize practical experience
from building a prototype testbed that utilizes beamforming antennas
for multihop communication.

Romit Roy Choudhury is a Ph.D candidate of Computer Science at the
University of Illinois at Urbana-Champaign. His research interests are
in networking and systems, with an emphasis on wireless mesh networks,
sensor networks, and ad hoc networks. Mr. Choudhury won the best paper
award at the 2003 Personal Wireless Communications conference for his
work on routing using directional antennas. He is a recipient of the
Motorola Center for Communications Fellowship during 2003-2005, and
the Vodafone Fellowship during 2005-2006. Further information is
available at http://www.crhc.uiuc.edu/~croy/.