Full-Duplex Beamforming Optimization for Near-Field ISAC

TL;DR

This paper presents a joint beamforming optimization framework for full-duplex near-field ISAC systems, enhancing power efficiency and sensing capabilities by leveraging spherical-wave propagation.

Contribution

It introduces a novel joint optimization method for transmit and receive beamforming in near-field ISAC, utilizing alternating optimization and relaxation techniques.

Findings

FD near-field ISAC reduces transmit power compared to half-duplex.

The proposed method effectively detects multiple targets at the same angles.

Simulation shows improved power efficiency and sensing performance.

Abstract

Integrated Sensing and Communications (ISAC) is a promising technology for future wireless networks, enabling simultaneous communication and sensing using shared resources. This paper investigates the performance of full-duplex (FD) communication in near-field ISAC systems, where spherical-wave propagation introduces unique beam-focusing capabilities. We propose a joint optimization framework for transmit and receive beamforming at the base station to minimize transmit power while satisfying rate constraints for multi-user downlink transmission, multi-user uplink reception, and multi-target sensing. Our approach employs alternating optimization combined with semidefinite relaxation and Rayleigh quotient techniques to address the non-convexity of the problem. Simulation results demonstrate that FD-enabled near-field ISAC achieves superior power efficiency compared to half-duplex and far-field benchmarks, effectively detecting targets at identical angles while meeting communication requirements.