Multi-User Methods for Vibrational Radar Backscatter Communications

In this paper, we compare the performance between two multi-user processing methods in vibrational radar backscatter communications (VRBC). VRBC is a low-latency, scalable communications solution that uses millimeter-wave radars as vibrometers while also allowing them to perform sensing as usual. It allows for vibrational modulation on nearby surfaces to be decoded from the phase of its radar backscatter without requiring RF bandwidth sharing or changes to the radar waveform. One advantage of VRBC is that a single receiver can simultaneously decode messages from multiple users provided they are spatially separable from the radar's perspective. This paper discusses both range-Doppler and direct de-chirped signal processing for multi-user VRBC. We present simulation results that show better performance can be achieved using direct de-chirped signal processing. Additionally, we demonstrate that this method continues to allow for transponder separation in range just as the range-Doppler based approach traditionally does.