Collision Resolution in RFID Systems Using Antenna Arrays and Mix Source Separation
To address tag identification failure caused by signal collisions in RFID systems, this paper proposes a novel pilot-free signal recovery method leveraging antenna arrays and blind source separation. The method introduces a hybrid objective function that jointly incorporates the Zero-Forcing Constant-Modulus (ZFCM) criterion and a newly designed ambiguity suppression criterion, effectively mitigating phase and amplitude ambiguities inherent in conventional ZFCM-based beamformer estimation; gradient descent optimization ensures efficient solution convergence. By fully exploiting the spatial resolution of antenna arrays, the approach achieves high-precision and robust separation of concurrent tag signals—without requiring channel state information, tag location knowledge, or pilot symbols. Experimental results demonstrate substantial improvements in identification accuracy under high-density tag scenarios, establishing a scalable physical-layer multiple-access solution for passive RFID systems.