UVa/SOWN Website

SOWN Design Goals

Develop an operational Self-Organizing Wireless Network (SOWN) 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 SOWN system 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.

SOWN Software Architecture

The above graph provides an overview of the SOWN architecture. The SOWN 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 SOWN modules, which are also written in NesC. 

The application components are specially designed for the surveillance purpose. 

•  EnviroTrack, which provides entity-based tracking service,
•  Classification components, which provides four types of target differentiation , 
•  Velocity regression , which  provides target speed and bearing estimation, 
•  False alarm Filtering, which differentiates the real and false targets.

The Middleware components are designed to be application independent. 

• Time synchronization module is responsible for synchronizing the local clocks of the motes with the clock of the base station. 
• Localization module is responsible for ensuring that each mote is aware of its location.
• Configuration module is responsible for dynamical reconfiguring the system when system requirement changes. 
• Asymmetric Detection is designed to aid routing module to select high-quality links to the base. 
• Radio Wakeup module is used to alert non-sentry motes when a significant event happens.
• The Sentry Service component and Tripwire Management  are  responsible  for  power  management. 
• The Group Management  component is responsible for collaborative  detection and tracking of events. 

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.

This project is sponsored by DARPA (Defense Advance Research Projects Agency). For more information, please visit the website http://www.cs.virginia.edu/~control