Integrated Radar and Communication Via Linear-Motion Backscatter: A Proof of Concept

Abstract

Integrated radar and communications systems conventionally rely on complex electronic radio-frequency modulation, presenting power and security limitations for low-power Internet of Things (IoT) nodes. This paper proposes a novel linear-motion backscatter communication framework that transforms controlled mechanical kinematics into a digital modulation medium, allowing standard Doppler radar to actively decode data from physical displacements. A fundamental challenge in this architecture is the severe spectral contamination caused by the inherent return-to-initial mechanical movements of the actuator. To address this physical constraint, a time-gated short-time Fourier transform (STFT) demodulation strategy is developed to mathematically isolate the data-bearing signaling phase and neutralize the counter-Doppler interference generated during the mechanical recovery phase. Simulation results demonstrate that the proposed temporal gating technique successfully eliminates the error floor phenomenon inherent to conventional continuous-integration methods. Furthermore, empirical validation using a continuous-wave software-defined radar (SDRadar) testbed serves as a proof of concept to demonstrate the physical feasibility of the framework in cluttered indoor environments. Experimental evaluations demonstrate successful kinematic modulation up to a line-of-sight distance of 15 m. The physical trials also reveal that mechanical inertia and vibrations can induce burst errors that overwhelm basic parity-check forward error correction (FEC), highlighting the unique channel characteristics of mechanical backscatter. These findings establish the proposed kinetic modulation scheme as a robust, hardware-minimalistic, and physically secure alternative for future backscatter communication networks.