VigilNet

“An Integrated Sensor Network System for Energy-Efficient Surveillance”

System Overview

VigilNet is one of the major efforts in the sensor network community to build an integrated sensor network system for surveillance missions. The focus of this effort is to acquire and verify information about enemy capabilities and positions of hostile targets. Such missions often involve a high element of risk for human personnel and require a high degree of stealthiness. Hence, the ability to deploy unmanned surveillance missions, by using wireless sensor networks, is of great practical importance for the military. Because of the energy constraints of sensor devices, such systems necessitate an energy-aware design to ensure the longevity of surveillance missions.

VigilNet currently consists about 40,000 lines of NesC and Java code, running on XSM, Mica2 and Mica2dot platforms. The complete system is designed to scale to at least 1000 XSM motes and cover minimal 100x1000 square meters to ensure operational applicability.

VigilNet Design Goals

Develop an operational self-organized wireless network to provide tripwire-based surveillance with a sentry-based power management scheme, in order to achieve minimum 3–6 months life time with current hardware capability. The system should also support timely detection, tracking and coarse granular classification of vehicle and personnel targets over all kinds of terrain.

The general objective of VigilNet system (pervious known as SOWN) is to alert the military command and control unit in advance to the occurrence of events of interest in hostile regions. The event of interest for our work is the presence of moving vehicles in the deployed region. The deployed sensor devices must have the ability to detect and track vehicles in the region of interest. Successful detection and tracking requires that the application obtain the current position of a vehicle with acceptable precision and confidence. When the information is obtained, it has to be reported to a remote base station within an acceptable latency.

VigilNet Software Architecture

The above graph provides an overview of the VigilNet architecture. The VigilNet architecture is built on top of TinyOS. TinyOS is an event driven computation model, written in NesC specifically for the motes platform. TinyOS provides a set of essential components such as hardware drivers, scheduler and basic communication protocols. These components provide low-level support for VigilNet modules, which are also written in NesC.

The application components are specially designed for the surveillance purpose.

The Middleware components are designed to be application independent.

Time synchronization, localization, and routing comprise the lower-level components and form the basis for implementing the higher-level middleware services, such as aggregation and power management.

The sentry and tripwire service conserves energy of the sensor network by selecting a subset of motes, which we define as sentries, to monitor events. The remaining motes are allowed to remain in a low-power state until an event occurs. When an event occurs, the sentries awaken the other motes in the region and the group management component dynamically organizes the motes into groups in order to enable collaborative tracking. Together, these two components are responsible for energy-efficient event tracking.

Support

This project is sponsored by DARPA (Defense Advance Research Projects Agency). For information on our other projects, visit UVA's Wireless Sensor Network site.