The research
has supported in part by the following: National Science Foundation
grant ANI-9985446, Sloan Fellowship grant BR-3989, Air Force Office of
Scientific Research grant F49620-01-1-0365, the Stanford Networking
Research Center and the Stanford Graduate Fellowships.
Energy
Efficient Wireless Communication:
- Energy-efficiency is important in
wireless networks, such as wide area voice and data networks and
wireless LANs. The advance of the "ubiquitous networking" idea has
made energy efficiency even more important, since in the multi-hop
(or ad-hoc) network architectures energy influences node lifetime,
and therefore, network lifetime.
- The energy consumed by a wireless
node can be considered to have two components: First,
"Receiving/Processing Energy", which is the energy consumed in
standby mode or when receiving data; and second, "Transmission
Energy", which is the energy needed to transmit data over the radio
link. We address the latter. In fact, as a rule of thumb, when network
diameter exceeds ~100 m, transmission energy is dominant.
- In our research we consider
transmitting information with minimum energy, rather than at the fastest
rate, which has been the focus of classical channel coding. This
problem is especially interesting and important in the case of
packetized data, which has not been well understood since previous
research on transmission power control usually addressed
continuous data. We develop novel scheduling algorithms for
energy-efficient packet transmission with certain delay
guarantees.
Publications:
- "Reliable Communication of
Finite Amount of Information with Minimum Energy", A. El Gamal, E.
Uysal, B. Prabhakar. In press.
- "Energy-efficient Packet
Transmission over a Wireless Link'', E. Uysal-Biyikoglu, B.
Prabhakar, A. El Gamal. .in IEEE/ACM Trans. Networking. Aug.
2002.
- "Adaptive Transmission of
Variable-Rate Data over a Fading Channel for Energy Efficiency", E.
Uysal-Biyikoglu, A. El Gamal, B. Prabhakar. Globecom 2002.
- "Energy-efficient
Scheduling of Packet Transmissions over Wireless Networks" , A. El
Gamal, C. Nair, B. Prabhakar, E. Uysal-Biyikoglu, S. Zahedi. Infocom 2002.
- "Energy-efficient
Transmission over a Wireless Link via Lazy Packet Scheduling", B.
Prabhakar, E. Uysal-Biyikoglu, A. El Gamal. Infocom 2001, Alaska.
Sensor
Networks:
- It is well-known that for
energy-constrained wireless networks of sensors and actuators selection
of links with high packet success rate helps to ensure reliable
long-term operation. In collaboration with Bosch
RTC, during the implementation of a protocol targeting
industrial applications of such systems, we found that it is
advantageous to acquire accurate information about the
availability and quality of the RF communication links prior to the
network topology formation.
- Link assessment as part of the
initialization process, accomplishes this task by assessing a
sufficient number of packets exchanged between neighboring nodes.
- We introduce two different link
assessment methods: A random scheme is evaluated which allows for a
probabilistic guarantee of collision-free packet exchange. Next, a
general method is described which employs `constant-weight codes' and
provides a deterministic guarantee of success. In particular,
special classes of constant-weight codes which are cyclically
permutable (also known as optical orthogonal codes) are considered
and it is shown that due to additional properties of these codes
they make the link assessment process simpler.
- Energy-efficiency is also very
important in wireless sensor networks, so different methods are
optimized and compared based on their energy/time requirements, and
implementation complexity.
Publications:
- “Measurement and
Characterization of Link Quality Metrics in Energy Constrained Wireless
Sensor Networks”, D. Lal, A.
Manjeshwar, F. Herrmann, E. Uysal-Biyikoglu, A. Keshavarzian, Globecom
2003.
- “Energy-Efficient Link
Assessment in Wireless Sensor Networks”, A. Keshavarzian, E.
Uysal-Biyikoglu, A. Manjeshwar, F. Herrmann. Under review.
Ad-Hoc
Wireless Networks:
Publications:
ISNL
|
Copyright © 2003 Stanford University
Last modified: 8 Sept 2003
Send comments and questions to abtink@stanford.edu
|