Adaptive Transmission for Energy Efficiency in Wireless Data Networks

Adaptive Transmission for Energy Efficiency
in Wireless Data Networks

Prof Brian Wendell (left) and Abbas El Gamal (right)

Presenter: Abbas El Gamal

Host: Alon Orlitsky, Professor in the Department of Electrical and Computer Engineering, University of California, San Diego - contact Prof. Orlitsky through Leah Bellacera at lbellace@soe.ucsd.edu

Date: Friday, May 10, 2002

Time: 1:15 PM, Reception to Follow

Location: CMRR Auditorium, UCSD Campus, La Jolla (directions and parking information)

Live Webcast: http://earth.ucsd.edu:8080/ramgen/encoder/elgamal.rm
Courtesy: California Institute for Telecommunications and Information Technology [Calit²]

Abstract
In a conventional wireless communication setting, senders are assumed to always have data to transmit, and the goal is to transmit data reliably at the highest possible rates in the presence of noise, interference, and fading, subject to average transmission power constraints. This problem has been extensively researched and adaptive transmission schemes have been developed to combat interference and fading. Recently, there has been growing interest in wireless data networks, where data at each sender is bursty and energy efficiency is a key concern. Burstiness implies that a sender may from time to time have no data to send and at other times have too much data to send. As a result, transmission schemes developed with the assumption of continuously available data may cause long packet delays and/or high transmission energy.

In this talk we discuss the problem of minimizing transmission energy under delay constraints in a wireless data network by judiciously adapting packet transmission powers and rates to data rates (backlogs) as well as to interference and fading. We discuss four scenarios, (i) wireless link with fading, (ii) downlink, (iii) uplink, and (iv) relaying. Optimal offline adaptation algorithms are presented. Online algorithms based on a simple look-ahead buffer are presented and shown to perform close to optimal and to be significantly more energy efficient than schemes such as water-filling when data is bursty.

Bio
Abbas El Gamal received the B.S. degree in electrical engineering from Cairo University in 1972, the M.S. degree in statistics and the PhD degree in electrical engineering from Stanford University in 1977 and 1978, respectively. From 78-80 he was an Assistant Professor of Electrical Engineering at the University of Southern California. He joined the Stanford faculty in 1981, where he is currently a Professor of Electrical Engineering. From 84-88, while on leave from Stanford, he was Director of LSI Logic Research Lab, then cofounder and Chief Scientist of Actel corporation. From 1990-1995 he was a cofounder and Chief Technical Officer of Silicon Architects, which was acquired by of Synopsys. El Gamal is currently a principal investigator on the Stanford Programmable Digital Camera project. His research interests include: CMOS image sensors and digital camera design, image processing, network information theory, and electrically configurable VLSI design and CAD. He has authored or coauthored over 100 papers and 25 patents in these areas. He serves on the board of directors and advisory boards of several IC and CAD companies. He is a Fellow of the IEEE and a member of the ISSCC Technical Program Committee.

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