Abstract
Localization is the process of determining the location of an object or device in an environment, and it can be achieved using radio frequency signals in wireless communication systems. Localization can be achieved using active or passive localization methods. Active localization is the most accurate but power-intensive, while passive localization is used in an environment where a targeted object does not have any devices. Consequently, this review paper is centred on the passive localization technique using radio tomography images, wherein object location is estimated using received signal strength measurements. The review paper presents passive localization as an improvement over active localization methods, problems, and limitations of tomography for Received Signal Strength Indicator (RSSI), recent contributions, and possible research directions. This review paper provides a broad and generic perspective of the ongoing research on passive localization, which might benefit researchers and professionals in wireless communications, localization, and signal processing.