Extended-Range Two-way Radar Backscatter Communication with Low-Power IoT Tags

This paper introduces BiScatter2 as an extension of BiScatter [3], an integrated radar backscatter communication and sensing system. BiScatter2 provides simultaneous uplink and downlink communications, and precise radar-based sensing and localization. By refining the signal processing techniques and tag architecture design, BiScatter2 extends the operational range, setting a new baseline for two-way radar backscatter systems. This functionality is enabled through the use of chirp-slope-shift-keying modulation applied to Frequency Modulated Continuous Wave (FMCW) radars. BiScatter2 incorporates passive differential circuitry on backscatter tags for efficient, low-power decoding and extends its coverage range by combining the tag decoder and retro-reflective structure. Our evaluation results show an increase of 46% maximum range under the same throughput in downlink communication, which increases the original work's capability for commercial radars.