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DBRAA: Sub-6 GHz and Millimeter Wave Dual-Band Reconfigurable Antenna Array for ISAC

Kangjian Chen, Chenhao Qi, Octavia A. Dobre

TL;DR

This work introduces a dual-band reconfigurable antenna array (DBRAA) that supports ISAC in sub-6G and mmWave bands using a shared aperture. Sub-6G beamforming is achieved via reconfigurable antenna selection (RAS) and a fast FS-JBAS search, while mmWave beamforming uses a reconfigurable hybrid architecture (RHB) solved by an ADMM-RHB algorithm. A dual-band ISAC beamforming problem is formulated and decoupled into sub-6G and mmWave subproblems, with a power-sharing strategy to maximize mmWave sum-rate under sub-6G QoS and sensing constraints. Simulation results show that RAS outperforms conventional antenna selection and RHB outperforms traditional hybrid approaches, highlighting the practical potential for integrated sensing and communications across dual bands. The proposed framework offers a scalable path toward efficient, shared-aperture ISAC systems for future 6G networks.

Abstract

This paper proposes a dual-band reconfigurable antenna array (DBRAA), enabling wireless capabilities in both sub-6 GHz (sub-6G) and millimeter wave (mmWave) bands using a single array. For the sub-6G band, we propose a reconfigurable antenna selection structure, where each sub-6G antenna is formed by multiplexing several mmWave antennas, with its position dynamically adjusted using PIN diodes. For the mmWave band, we develop a reconfigurable hybrid beamforming structure that connects radio frequency chains to the antennas via phase shifters and a reconfigurable switch network. We then investigate integrated sensing and communications (ISAC) in sub-6G and mmWave bands using the proposed DBRAA and formulate a dual-band ISAC beamforming design problem. This problem aims at maximizing the mmWave communication sum-rate subject to the constraints of sub-6G communication quality of service and sensing beamforming gain requirements. The dual-band ISAC beamforming design is decoupled into sub-6G beamforming design and mmWave beamforming design. For the sub-6G beamforming design, we develop a fast search-based joint beamforming and antenna selection algorithm. For the mmWave beamforming design, we develop an alternating direction method of multipliers-based reconfigurable hybrid beamforming algorithm. Simulation results demonstrate the effectiveness of the proposed methods.

DBRAA: Sub-6 GHz and Millimeter Wave Dual-Band Reconfigurable Antenna Array for ISAC

TL;DR

This work introduces a dual-band reconfigurable antenna array (DBRAA) that supports ISAC in sub-6G and mmWave bands using a shared aperture. Sub-6G beamforming is achieved via reconfigurable antenna selection (RAS) and a fast FS-JBAS search, while mmWave beamforming uses a reconfigurable hybrid architecture (RHB) solved by an ADMM-RHB algorithm. A dual-band ISAC beamforming problem is formulated and decoupled into sub-6G and mmWave subproblems, with a power-sharing strategy to maximize mmWave sum-rate under sub-6G QoS and sensing constraints. Simulation results show that RAS outperforms conventional antenna selection and RHB outperforms traditional hybrid approaches, highlighting the practical potential for integrated sensing and communications across dual bands. The proposed framework offers a scalable path toward efficient, shared-aperture ISAC systems for future 6G networks.

Abstract

This paper proposes a dual-band reconfigurable antenna array (DBRAA), enabling wireless capabilities in both sub-6 GHz (sub-6G) and millimeter wave (mmWave) bands using a single array. For the sub-6G band, we propose a reconfigurable antenna selection structure, where each sub-6G antenna is formed by multiplexing several mmWave antennas, with its position dynamically adjusted using PIN diodes. For the mmWave band, we develop a reconfigurable hybrid beamforming structure that connects radio frequency chains to the antennas via phase shifters and a reconfigurable switch network. We then investigate integrated sensing and communications (ISAC) in sub-6G and mmWave bands using the proposed DBRAA and formulate a dual-band ISAC beamforming design problem. This problem aims at maximizing the mmWave communication sum-rate subject to the constraints of sub-6G communication quality of service and sensing beamforming gain requirements. The dual-band ISAC beamforming design is decoupled into sub-6G beamforming design and mmWave beamforming design. For the sub-6G beamforming design, we develop a fast search-based joint beamforming and antenna selection algorithm. For the mmWave beamforming design, we develop an alternating direction method of multipliers-based reconfigurable hybrid beamforming algorithm. Simulation results demonstrate the effectiveness of the proposed methods.

Paper Structure

This paper contains 32 sections, 85 equations, 12 figures, 3 algorithms.

Table of Contents

  1. Introduction
  2. System Model
  3. Dual-Band Reconfigurable Antenna Array
  4. Overview
  5. RAS Structure for the Sub-6G Band
  6. RHB Structure for the mmWave Band
  7. Sub-6 GHz System Model
  8. mmWave System Model
  9. Problem Formulation
  10. Problem Formulation for Sub-6G Band
  11. Problem Formulation for mmWave Band
  12. Dual-Band Problem Formulation
  13. Sub-6G Beamforming Design
  14. Subproblem of (P1)
  15. Initialization
  16. ...and 17 more sections

Figures (12)

  • Figure 1: Illustration of the sub-6G and mmWave dual-band ISAC systems.
  • Figure 2: Illustration of the dual-band reconfigurable antenna array.
  • Figure 3: Illustration of the reconfigurable antenna selection structure.
  • Figure 4: Illustration of the beamforming structure for the dual-band reconfigurable antenna array.
  • Figure 5: Illustration of the Cartesian coordinate system for the sub-6G channel.
  • ...and 7 more figures