Harnessing Ambient RF Waves for Novel Applications

The wireless revolution has created a mobile information society. One key element in this revolution has been the use of RF waves for information transmission. RF waves can be used directly for transmission but it is also possible to harness RF waves that are already in use for other applications. These existing RF waves can be thought of as ambient RF waves or signals and can be harnessed for a wide variety of applications. Using sunlight as an analogy, for ambient RF waves, we can deduce that applications such as cameras, navigation, solar cells, heliostats and heliographs can be readily carried over to ambient RF waves in the form of imaging, device free location estimation, ambient RF energy harvesting, reconfigurable intelligent surface (RIS) and ambient backscatter communication (AmBC). In this paper we explore technologies and techniques that can harness ambient RF waves for our benefit, without adding further RF transmissions to the environment. In essence we treat the harnessing of ambient RF waves as a single research area rather than a collection of unrelated applications. This allows us to explore and develop new and novel applications. It also allows us to focus on the fundamental phenomena and applications of ambient RF waves.