Device-Free Motion Tracing Using WiFi Signals

Fine-grained human motion tracing — the ability to trace the trajectory of a moving human hand or leg, or even the whole body — is a general capability that is useful in a wide variety of applications. It can be used for gesture recognition and virtual touch-screens (e.g. Kinect-style natural user interfaces), activity recognition, monitoring of young infants and the elderly, or security applications such as intruder detection. Motivated by these applications, depth-sensing-based systems have been developed to implement motion tracing capabilities in cameras; however, these devices are limited because they have a constrained field of view (around 2 to 4 m range with a 60-degree aperture), and do not work in non-line-of-sight scenarios, preventing their use in many applications such as whole-home activity recognition, security, and elderly care.