Contents 1. Introduction
Wireless technologies have propelled major advances in various industries including telecommunications, entertainment, and smart environments. Today, radios are embedded in cellphones, wearable devices, sensors, and control systems. Yet, in all of these diverse domains, radios are used for communications. Even when embedded in a sensor, the radio signals are used for communicating the sensed data, rather than performing the sensing function. We argue that future innovations should leverage radio signals for sensing. Radio signals are fascinating creatures: they travel in space, traverse walls and occlusions, and reflect off people and objects. The reflected signals are modulated by people’s movements, actions, respiration, and heart beats. By analyzing such radio reflections, we can learn much information about people and their physiological signals, and leverage such knowledge to enable new capabilities and novel applications.
