Multipath analyses of moving targets in enclosed structures using Doppler radars

In through-the-wall radar and urban sensing applications, detection, localization, and classification of targets are highly desirable. The presence of the targets inside buildings, and in close proximity of walls, floors, and ceilings, leads to a rich multipath environment. Multipaths can introduce false targets, thereby degrading target detection, localization, and classification performances. A multipath model based on the principles of ray tracing is advocated in this paper. We consider a diffused target moving in an enclosed urban structure being observed by a stationary Doppler radar. The model is verified using both simulated and experimental data. Further, we address the inverse problem of identifying the true Doppler peak given the Doppler spectrum, and show that the solution exists under partial knowledge of the angles of arrival.