Wireless video sensor networks have the potential to significantly enhance national security and emergency response efforts, and the National Science Foundation (NSF) is supporting research at Virginia Tech aimed at extending the lifetime and strengthening the performance of these networks. Assistant Professor Thomas Hou and Professor Scott Midkiff of the university's electrical and computer engineering department have received a $225,000 Information Technology Research (ITR) grant to study factors that affect network lifetime.

Composed of interconnected, miniature video cameras and low-power wireless transceivers that process, send and receive data, wireless video sensor networks can provide real-time visual data in situations where accurate surveillance is critical, explained Hou, the principal investigator on the ITR project. These networks can help reduce the impact of security breaches on the nation's infrastructure and improve the government's ability to prevent, detect, respond to and recover from both manmade and natural catastrophes.

In March 2003 Hou received a Young Investigator Award grant from the Office of Naval Research (ONR) in support of his work to enhance the technology in a number of ways. Hou and Midkiff will use the NSF ITR grant to focus on the issues of power use and network topology.

Receiving, processing and transmitting video information places a high demand on the batteries that supply power to a wireless video network. This poses a problem, particularly when networks are operated in remote locations. "A major challenge of our research will be maximizing the lifetime of networks using components with limited battery power," Hou said.

Hou and Midkiff believe that improving network topology -- the arrangement by which network components are connected -- is the key factor in maximizing power efficiency. "An analysis of power dissipation at video sensor nodes suggests that communication consumes significantly more energy than any other activity," Hou noted. "By adjusting the topology of the network, we can optimize the transmitter power of video sensor nodes and extend network lifetime."

The researchers will employ algorithms (mathematical problem-solving procedures) and techniques developed in the field of computational geometry to help determine the most beneficial topology adjustments. "Developing good solutions for these networking problems is the key to unlocking the full potential of a large-scale wireless video sensor network," Hou said.

As part of the ITR project, Hou and Midkiff also plan to develop a software toolkit that will implement the topology control techniques they discover, and to incorporate their findings into an advanced wireless and sensor networks course at Virginia Tech.

Hou, who joined the Virginia Tech faculty in 2002, is a co-recipient of the 2002 Institute of Electrical and Electronics Engineers (IEEE) International Conference on Network Protocols Best Paper Award and the 2001 IEEE Transactions on Circuits and Systems for Video Technology Best Paper Award. Hou received his bachelor's degree from the City College of New York, a master's degree from Columbia University, and his Ph.D. degree from Polytechnic University in Brooklyn, New York, all in electrical engineering.

Since coming to Virginia Tech in 1986, Midkiff has become a leader in a number of wireless and computer technology initiatives at the university. He is the director of the NSF-sponsored Integrated Research and Education in Advanced Networking program and an associate of both the Center for Wireless Telecommunications and the Mobile & Portable Radio Research Group. Midkiff received his bachelor's degree and Ph.D. from Duke University and a master's degree from Stanford University.