Radar for indoor surveillance: State of art and perspectives

Through wall indoor surveillance and monitoring is an emerging area of research and developments in many real-life applications, including security and search and rescue. In this context, it is important to deploy remote sensors able to glean information about the presence of people in indoor areas. Radar devices based on the exploitation of electromagnetic signals represent an attractive sensing modality. When operating at frequencies from hundreds of MHz to few GHz, they are capable to penetrate common construction materials enabling the detection of people in inaccessible environments. Two different types of surveillance radars are considered in this paper. The first one exploits the synthetic aperture concept with the aim to detect, locate, and track multiple subjects in the scene. The second one illuminates the scene from a fixed position and exploits the Doppler effect. Despite the limited information available with respect to aperture radars, Doppler radars allow the detection of moving targets behind walls and inside enclosed structures. This work presents a brief overview of recent developments in the field of radar data processing for indoor monitoring together with their assessment by means of numerical and experimental tests.