Artificial Noise-Aided Transmit and Receive Beamforming for Securing Multi-Tag Backscattering

Advanced security solutions are essential for sustainable and autonomous networking in 6G systems. Secure backscatter communications (BSC) are crucial to protecting data integrity and confidentiality against evolving threats in green communication networks. This form of wireless communication involves devices reflecting signals to the source and extends beyond existing security solutions. Physical layer security (PLS) solutions have emerged as a promising avenue for developing adaptive, robust, and lightweight security measures. We propose a unique approach involving beamforming at the multiantenna transceiver, known as the reader, to enhance data confidentiality in multi-tag monostatic backscattering systems. Our innovative framework protects against security breaches due to eavesdroppers and optimizes the sum-secrecy rate among the tags by integrating transceiver beamforming and artificial noise techniques. Given the non-convex nature of the original problem, we propose two efficient solutions: a transmitter design for a given combiner using fractional programming and a closed-form optimal receiver design for a specified precoder configuration. Comprehensive numerical analyses validate the proposed solutions and verify key analytical claims while also quantifying the significant performance gains achieved over benchmark schemes across various system parameters.