Dynamic Sleep and Transmission Scheduling in Wireless Ad-hoc and Sensor Networks
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Date: 11-01-2006
Start Time:
1:30pm
End Time: 2:30pm
Speaker: Koushik Kar
From:
Rensselaer Polytechnic Institute
Location: CEPSR Interschool Lab, 7th floor
Hosted by:
Distributed Network Analysis (DNA) Lab
ABSTRACT:
In near future, large-scale ad-hoc and sensor networks are expected to
form the backbone of a vast range of applications, including military and
relief operations, intra-community communication, and environmental and
health monitoring. Due to the shared nature of the wireless medium and
limitations on battery capacities, these networks are considerably more
constrained in terms of bandwidth and energy than traditional wired
networks. Thus efficient management of bandwidth and energy is crucial to
the successful operation of ad-hoc and sensor networks. On the other hand,
due to their large-scale, dynamic nature, resource management algorithms
designed for such networks must be distributed in nature, and have a low
per-node message-complexity.
In this talk, we will describe our recent results on two key resource
management questions in such networks, namely sleep scheduling and
transmission scheduling. We will first discuss the question of dynamic
sleep scheduling in a rechargeable sensor network, with the objective of
maximizing a time-average generalized coverage metric by appropriately
putting sensors to `sleep' and waking them up when necessary. Under random
energy discharge/recharge processes, we will argue that a simple, local
threshold policy is provably optimal in certain special cases, and present
simulation results that demonstrate the near-optimal performance of this
policy in general networks. We will also show, through analysis and
simulation, that spatial correlation in the recharge/discharge processes
worsens system performance. We will then address the question of
transmission scheduling in a wireless ad-hoc network, with the goal of
maximizing the long-term throughput of the system under random packet
arrivals. The transmission scheduling question will again be discussed in
a stochastic optimization framework; we will show that a class of simple
scheduling policies, maximal scheduling, that can be implemented with
low-complexity local message exchanges, attains a constant fraction of the
maximum system throughput. Finally, we will compare and contrast the sleep
and transmission scheduling questions and our approaches in addressing
them, and outline open research issues.
BIOGRAPHY:
Koushik Kar is an assistant professor in the Electrical, Computer &
Systems Engineering department at Rensselaer Polytechnic Institute, Troy,
NY, a position he has held since 2002. He received his B.Tech. degree in
Electrical Engineering in 1997 from the Indian Institute of Technology,
Kanpur, and his Ph.D. in Electrical & Computer Engineering in 2002 from
the University of Maryland, College Park. Dr. Kar's research interests
are in modeling and performance optimization of communication networks,
and includes issues like access control, traffic engineering, congestion
control and energy management in such networks. His recent research work
is primarily focused on developing distributed optimization algorithms for
efficient usage of bandwidth and energy in wireless ad-hoc and sensor
networks. Dr. Kar received the Career Award from the National Science
Foundation in 2005.