Design and development of radio tomographic imaging system

Abstract

Radio tomographic imaging (RTI) is an emerging imaging technique that utilizes the shadowing losses on links between multiple pairs of wireless nodes within the monitoring area to estimate the attenuation of physical objects. In recent years, RTI has gained huge interest from the researchers in device-free localization (DFL) field due to its ability in generating an image to localize a target within the monitoring area. From the literature studies, researchers are primarily focused on the study of characterizing RSSI attenuation for different purposes such as human presence detection, privacy-preserving localization, indoor and outdoor localization. However, to the best of the authors' knowledge, there is no research conducted in studies the effects of phantoms with different dimensions towards the changes in received signal strength indicator (RSSI) value. Therefore, this paper presents a design and development of the RTI system to study and characterize the behaviour of radio waves propagation when phantoms with different dimensions are present within the monitoring area. An overview of the proposed RTI system, the arrangement of sensor arrays and a few factors that should take into consideration when using the RF sensors such as ground effects, near field and far-field region of an antenna have been discussed in this paper. Also, the details of the experimental design have been explained. Based on the results obtained from the experiments, the RSSI value decreases gradually as the dimension of phantoms with water medium increases. This is because when the diameter of a phantom with water medium increased, the water content inside the phantom also increased. Also, water is a high-attenuating medium and its dielectric constant is 80. Therefore, when the diameter of a phantom with water medium increased, the energy of the EM waves is absorbed and scattered more. This caused the attenuation of EM waves increased and resulted in lower RSSI value.