Device free localization technology for human detection and counting with RF sensor networks: A review

Wireless sensor networks (WSNs) have shown many attractive features in a lot of real‐world applications not only for communication but also for localization and tracking purposes. This paper presents a comprehensive survey of recently growing concept device-free localization (DFL) system- its basic concept, potential applications, and existing methods and algorithms. This paper discussed the revolution of DFL technology from traditional detection methods to the most attractive solution called Radio Tomographic Imaging (RTI) that can detect people or objects and image the movement lying within the sensed area. This paper introduces the existing DFL methods and algorithms especially for the model-based RTI methods, describes on the available and efficient device-free people detection, counting and activities recognition methods, presents several challenges in DFL system and discusses open research issue for real implementation as well as recent improvement strategies to improve the performance of the DFL system in term of multi targets localization and counting accuracy.