Passive imaging strategies for real-time tracking of non-cooperative targets in security applications

The localization of passive targets has been widely investigated in the field of security applications. In such a context, the target is non-cooperative, i.e. transceiver-free and not actively associated to any monitoring system. These constraints make the detection and localization process challenging from the sensing technology viewpoint. Standard solutions adopt dedicated and complex sensors (e.g., video, audio, infrared sensors) that require accurate installation, calibration, and maintenance. Alternative passive imaging strategies based on the exploitation of wireless signals transmitted by low-cost devices have been also proposed in the state-of-the-art. In this paper, the advantages and limitations of such solutions are investigated and the concept of opportunistic exploitation of standard wireless architectures is introduced in order to show and discuss the applicability to security-related applications.