An ISAC-ready Full-Duplex Backscatter Architecture for the mmWave IoT
Achieving long-range, high data rate, concurrent two-way mmWave communication with power-constrained IoT devices is fundamental to scaling future ubiquitous sensing systems, yet the substantial power demands and high cost of mmWave hardware have long stood in the way of practical deployment. This paper presents Armstrong, the first mmWave full-duplex backscatter tag architecture, charting a genuinely low-cost path toward high-performance mmWave connectivity for ISAC systems. Armstrong operates in full duplex at ranges beyond 88m and beyond 200m in downlink alone, delivering 20x the reach of state-of-the-art systems while being over 100x cheaper than existing mmWave backscatter platforms. Enabling this leap is a novel low-power regenerative amplifier that provides 30 dB of gain while consuming only 7.7 mW during active transmission, paired with a regenerative rectifier that achieves state-of-the-art sensitivity down to -60 dBm. We integrate our circuits on a compact PCB and evaluate it across diverse downlink and uplink scenarios, where it achieves 1 Kbps BERs of less than 10^{-1} at 200m and 88m, respectively, demonstrating resilient, high-quality communication even at extended ranges.