Toward a rapidly deployable radio tomographic imaging system for tactical operations

The ability for special operations forces (SOF) to rapidly deploy a through-building tracking system upon arrival at a tactical operation, e.g., a hostage scenario, and thereby estimate the approximate locations of the people within the building has the potential to lower the risk of the operation and save lives. We study the feasibility of a rapidly deployed radio frequency (RF)-based tomographic imaging (RTI) system for use in tactical operations by Special Weapons and Tactics (SWAT) and other SOF, in which several low-power radio devices are placed around a building and used to image and track the motion of humans inside the building. Specifically, we identify and study the constraints of this application, such as the need for the sensor network to self-localize and self-calibrate with minimal input from the SOF. We implement and test, in a wide variety of experimental deployments, a real-time RTI tracking system which adheres to these constraints and provides valuable situational intelligence. We work in concert with local law enforcement and SWAT in order to obtain valuable feedback from end users. We show that our system is capable of providing useful tracking information (average errors of less than two meters) even when the self-localization results are inaccurate (up to three meters average error).