[Colloq] Reminder: Hiring Talk -Today, 2pm, Alberto Cerpa, UCLA

[Rachel Kalweit]

College of Computer and Information Science Colloquium

Presents:
Alberto Cerpa
UCLA

Who will speak on:
Low-Power Wireless Links Properties: Modeling and Applications in Sensor
Networks.

Friday, April 8, 2004
2:00pm
366 West Village H
Northeastern University

Abstract:
Advances in low-cost, low-power micro-sensor and radio design have led
to active research in large-scale networks of small, wireless, low-power
sensors and actuators.  Radio communication is one of the critical
components in any wireless distributed systems, but wireless sensor
networks make extensive use of communications in order to perform the
coordinated sensing tasks.  These systems will be deployed in many
environments the present very harsh conditions for wireless
communication using low-power radios, including multipath/fading
effects, reflections from obstacles, and attenuation from foliage.
Moreover, recently several landmark wireless sensor network deployment
studies clearly demonstrated a large discrepancy between experimentally
observed communication properties and properties produced by widely used
simulation models.

New approaches and models are required to deal with vagaries of the
communication channel.  In the first part of this talk, I motivate the
need for precise wireless link characterization and describe the
methodology used to collect extensive experimental data traces, using
different hardware, in different environment, under systematic varied
conditions. I perform statistical analysis on the data and provide sound
foundations for our conclusions by extracting relationships between
location (e.g distance) and communication properties (e.g. reception
rate) using non-parametric statistical techniques.  The objective is to
provide a probability density function that completely characterizes the
relationship. Furthermore, I study individual link properties and their
correlation with respect to common transmitters, receivers and
geometrical location.  Using the modeled communication properties, we
develop a series of wireless network models that produce networks of
arbitrary sizes with realistic properties.  I use an iterative
improvement-based optimization procedure to generate network instances
that are statistically similar to empirically observed networks.  I
evaluate the accuracy of the conclusions using our models on a set of
standard communication tasks, like connectivity maintenance and routing.

In the second part of this talk, I describe more deeply the temporal
properties of links in low power wireless communications.  I investigate
short term temporal issues, like lagged autocorrelation of individual
links, lagged correlation of reverse links, and consecutive same path
links.  I also study long term temporal aspects, gaining insight on the
length of time the channel needs to be measured and how often we should
update our models.  In addition, I explore how statistical temporal
properties impact routing protocols.  I analyze one-to-one routing
schemes and develop new routing algorithms that consider
autocorrelation, and reverse link and consecutive same path link lagged
correlations.  I have developed two new routing algorithms for the cost
link model: (i) a generalized Dijkstra algorithm with centralized
execution, and (ii) a localized distributed probabilistic algorithm.

Finally, I describe all the insight obtained by analyzing all these
data, and propose new research direction for network protocol and system
designers of sensor networks.

Short bio:
Alberto Cerpa is a Ph.D. candidate in Computer Science at the University
of California, Los Angeles (UCLA), working under the supervision of
Professor Deborah Estrin.  Since Fall of 2000 he has been working in the
Center for Embedded Networked Sensing (CENS) and the Laboratory for
Embedded Collaborative Systems (LECS) at UCLA. Cerpa received his M.Sc.
in Computer Science from the University of Southern California (USC) in
2000, his M.Sc. in Electrical Engineering from the University of
Southern California (USC) in 1998, and his Engineer Degree in Electrical
Engineer from the Buenos Aires Institute of Technology, Argentina in 1995.

Alberto Cerpa interests lie broadly in the computer networking and
distributed systems areas.  His recent focus has been systems research
in wireless sensor networks, with emphasis in wireless radio channel
measurement and characterization, network self-configuration, topology
control, routing algorithms, programming models, and development of
wireless testbeds.  He is also interested in Internet protocols and
operating systems issues.  In the past, he has been involved in active
networking, mobile IP, and protocol design and verification research.



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