Title: SPT-BASED POWER-EFFICIENT TOPOLOGY CONTROL FOR
          WIRELESS AD HOC NETWORKS

Speaker: Prof. David Wei, Fordham University, NY


ABSTRACT

An ad-hoc network is an infrastructureless wireless network proposed as an
alternative to cellular networks for use in areas where the communication
infrastructure does not exist (e.g. due to an earthquake or flood) or the
construction of a fixed infrastructure is inconvenient or impossible (e.g. on a
battlefield or in space). In such a network, each node is responsible for
serving not only as a user but also as a router. A wireless link between any
two nodes can be established if the radio transmission range of each node can
cover each other. In case of insufficient radio transmission range between the
two nodes, multiple "hops" may be required, whereby intermediate nodes
re-broadcast the messages until the destination node is reached.  The reliance
on wireless multi-hop communications to maintain connectivity among nodes adds
new complexity on the design and operation of the network.  The lack of a
physical backbone infrastructure poses a strong need of topology control of the
network. It has been shown that the performance of a protocol for an ad-hoc
network can be enhanced if the protocol is designed based on overlaying a
virtual infrastructure on the ad-hoc network.  Also, due to the finite power
supply of a mobile node, power conservation has been widely used as a primary
control parameter in the design of the protocols for wireless ad hoc networks.
Therefore, the problem of power-efficient topology control has been attracting
more and more researchers from the areas of wireless networking.

In this talk, we present a localized Shortest Path Tree (SPT) based algorithm
for constructing power-efficient topology for wireless ad hoc networks.  Each
mobile node determines its own transmission power based only on its local
information. The proposed algorithm first constructs local SPTs from the
initial graph, and then the total power consumption is further reduced by
allowing each mobile node to search and excise the replaceable links
individually. The constructed topology ensures network connectivity, and
possesses several desirable energy-efficient features: 1) its power stretch
factor is bounded and can be predetermined, 2) the power consumption is evenly
distributed among the mobile nodes, and 3) its total power consumption is lower
than that obtained from the best known algorithms. The performance improvements
of the proposed algorithm are demonstrated through extensive simulations.


Biography:
David S.L. Wei received his Ph.D. degree in Computer and Information Science
from the University of Pennsylvania in 1991.  He is currently an associate
professor of Computer and Information Science Department at Fordham University.
From May 1993 to August 1997 he was on the Faculty of Computer Science and
Engineering at the University of Aizu, Japan (as an Associate Professor and
then a Professor).  Dr. Wei has authored and co-authored more than 70 technical
papers in the areas of distributed and parallel processing, wireless networks
and mobile computing, and optical networks in various archival journals and
conference proceedings.  He served on the program committee and was a session
chair for several reputed international conferences.  He served as a co-chair
of Power Aware Communication and Software, Minitrack in the Software Track at
the 34th Hawaii International Conference on Systems Sciences (HICSS-34).  He is
a lead guest editor of IEEE Journal on Selected Areas in Communications for the
special issue on Mobile Computing and Networking.  Currently, Dr. Wei focuses
his research effort on wireless networks, mobile computing, and peer-to-peer
communications.