Keyless Range–Angle Secure Wireless Links in the Near-Field of an Ultra-Large-Scale RIS

Abstract

Physical-layer security (PLS) complements cryptography at the wireless edge, yet most existing systems confine secrecy to the angular domain: an eavesdropper on the legitimate direction—merely nearer or farther—still captures clean constellations. This poster presents NF-SecRIS, a prototype that attains range–angle (2D) PLS by operating a 784-element reconfigurable intelligent surface (RIS) in its radiating near field. A secure location modulation (SLM) scheme decouples spatiotemporal codebook design into near-field beam focusing, low-dimensional squeeze nulling, and randomized time-domain phase interleaving, generated in real time on a scalable master–slave FPGA fabric without key exchange. At 5.8 GHz, the legitimate user’s bit error rate (BER) stays below 10− 4, while eavesdroppers at other ranges or angles suffer BERs above 40%. We further report an empirically characterized region of admissible switching parameters and outline the open modeling and adversarial questions the system exposes.