ISAC with Backscattering RFID Tags: Beamforming and Codebook Design

TL;DR

This paper proposes a joint beamforming and codebook design for an integrated sensing and communication system using backscattering RFID tags, improving tag interrogation range and success rate under power constraints.

Contribution

It introduces a novel sector-based codebook design and beamforming strategies for multi-tag RFID systems within ISAC frameworks, addressing interference and power efficiency.

Findings

Proposed beamforming approaches effectively mitigate sensing-communication interference.

The sector-based codebook enhances RFID tag interrogation success rate.

Simulation results demonstrate improved interrogation range with minimized transmit power.

Abstract

This paper explores an integrated sensing and communication (ISAC) system with backscattering RFID tags. In this setup, an access point employs communication beams to serve communication users while leveraging a sensing beam to interrogate RFID tags. Under the total transmit power constraint of the system, our objective is to design a joint sensing and communication beamforming codebook by considering the tag interrogation and communication requirements. To lay a foundation for the codebook design problem, we first study the beamforming design problem in a single-tag scenario and investigate two approaches: (i) a zero-forcing approach with optimized sensing/communication power allocation, for which a closed-form solution is derived under a dominant sensitivity condition, and (ii) a joint sensing and communication beamforming design obtained by transmit power minimization. Then, we investigate the codebook design problem in a multi-tag scenario. To resolve this, we propose a sector-based joint sensing and communication beamforming codebook that scans the region of interest. For each sector, semidefinite relaxation and generalized Benders decomposition are employed to handle the resulting optimization. The simulation results show that the proposed joint beamforming designs can effectively mitigate the mutual interference between sensing and communication functionalities, thus enhancing the interrogation range of the tags with minimized transmit power. Also, the efficacy of the proposed sector-based codebook design has been demonstrated in terms of interrogation success rate, offering a promising approach for the ISAC-backscattering systems.