Precise localization encompassing diverse indoor spaces is the key to immersive interaction services. In practice, indoor localization often undergoes blind spots as RF is easily blocked by everyday objects ranging from concrete walls, metallic shelves, and partitions to electronics and appliances. This paper presents SuperSight, an NLOS localization for mmWave backscatter that, for the first time, achieves NLOS (non-penetrable) localization without multipath environment profiling/manipulation. The key insight of SuperSight is uniquely exploiting the mmWave features of highly directional and specularly reflected multipath in combination with the triangular tag array to yield sub-cm NLOS localization accuracy over 8 m range - an order of magnitude performance enhancement compared to the competitors. Circularly polarized, 77GHz retro-reflective tag ensures high precision and robustness across diverse reflectors and tag orientations. The prototype was evaluated across six different reflector materials (including metal, concrete, and plaster) and demonstrated in the corridor and office space to reveal x, y, z position accuracy of up to (metal reflector) 5.7 mm, 5.5 mm, 7.7 mm at 8 m range, with Yaw, Pitch, Roll accuracy of 0.22, 0.28, 0.1 degrees respectively.

Accurate and scalable localization is one of the keys to pervasive interaction with the Internet of Things. mmWave backscatter possesses great potential toward this goal - The abundant bandwidth of mmWave enables high-precision localization, and low-cost and ultra low-power backscatter tags enable massive deployment with minimum deployment cost and maintenance efforts. We present Hawkeye, a new mmWave backscatter that offers (i) submillimeter localization accuracy (ii) at over 2 m range, (iii) while consuming 2.25 μW power. At the heart of our design is the new Hawkeye super-resolution, which exploits the interplay between the tag FSK and FMCW radar to improve the localization performance by ×60 over conventional FMCW radar (i.e., c/2BW). Hawkeye readers were implemented on commodity 77 GHz radars and the tags were prototyped on PCB.

Accurate localization of a large number of objects over a wide area is one of the keys to the pervasive interaction with the Internet of Things. This paper presents Hawkeye, a new mmWave backscatter that, for the first time, offers over (i) hundred-scale simultaneous 3D localization at (ii) subcentimeter accuracy for over an (iii) hectometer distance. Hawkeye generally applies to indoors and outdoors as well as under mobility. Hawkeye tag's Van Atta array design with retro-reflectivity in both elevation and azimuth planes offers 3D localization and effectively suppresses the multipath. Hawkeye localization algorithm is a lightweight signal processing compatible with the commodity FMCW radar. It uniquely leverages the interplay between the tag signal and clutter, and leverages the spectral leakage for fine-grained positioning. Prototype evaluations in corridor, lecture room, and soccer field reveal 7 mm median accuracy at 160 m range, and simultaneously localize 100 tags in only 33.2 ms. Hawkeye is reliable under temperature change with significant oscillator frequency offset. Demo video: https://tinyurl.com/4zkwxatu