Passive Reduction of Phase Rotation and Doppler Shift on Moving Communication Systems by using Kramers-Kronig Receivers

The Kramers-Kronig (KK) receiver is gaining traction in the optical community for its simplistic architecture, but it has not been explored much at radio frequencies, even though its lightweight and passive RF front end suggests its use for IoT applications. In this Article, we argue this point further by showing its ability to reduce the effects of motion, such as Doppler shift and channel fading, by orders of magnitude. We show in theory that the shift seen in a KK receiver mimics the shift of the difference frequency as opposed to the carrier. Additionally, to show the improvement on the constellation, we physically move the receiver in a lab setting as well as emulate the Doppler shift on an orbiting body in software. The results show that KK receivers by nature reduce the needed complexity for IoT devices to track phase and frequency misalignment in a mobile environment.