Title: Utilizing Beamforming Antennas for Wireless Multihop Networks

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, achievable 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 a new MAC and routing protocol. I will also summarize practical experiences from building a prototype testbed that utilizes beamforming antennas for multihop communication.


Bio:
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. Romit 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/.