Multipath Doppler signatures from targets moving behind walls

Detection, localization, and tracking of moving targets are highly desirable in through-the-wall sensing applications. Since the indoor environment is rich in multipath reflective sources, such as walls, floor, and ceiling, the received signal is composed of the direct path and several multipath arrivals. However, on occasions, the direct path to the target may be blocked as the target traverses behind large metallic objects such as file cabinets, etc. In such cases, multipath is the only observable return and can be exploited to detect and maintain tracking of moving targets. In this paper, we provide range-Doppler analysis of multipath arrivals for a diffuse target moving in an enclosed urban structure, which provides insight for the development of through-the-wall detection and tracking techniques based on multipath exploitation.