ABSTRACT
While wireless has revolutionized mobile data communications, it also plays a major role as a sensing technology. Meteorologists routinely use wireless signals to scan the atmosphere for weather forecasts, astronomers use radio to probe deep space, geologists use radio frequencies for remotely sensing various Earth phenomenon, and airport authorities are increasingly using wireless signals at security gates to detect prohibited materials concealed by passengers. Recently, scientists are discovering techniques to monitor human activities and even vital signs, such as heart and breathing rates, simply by analyzing the wireless signals reflected by the human body. These advancements have created the potential for wireless to penetrate the growing mobile and IoT sensing market. This chapter first discusses the motivation and advantages for radio-based sensing followed by the working principles of the popular wireless sensing tools and techniques targeted at the IoT market. Specifically, this chapter covers wireless sensing based on WiFi and millimeter wave radars. [153 words]
