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3D Spherical Directly-Connected Antenna Array for Low-Altitude UAV Swarm ISAC

Haoyu Jiang, Zhenjun Dong, Zhiwen Zhou, Yong Zeng

Abstract

Recently a novel multi-antenna architecture termed ray antenna array (RAA) was proposed, where several simple uniform linear arrays (sULAs) are arranged in a ray-like structure to enhance communication and sensing performance. By eliminating the need for phase shifters, it also significantly reduces hardware costs. However, RAA is prone to signal blockage and has no elevation angle resolution capability in three-dimensional (3D) scenarios. To address such issues, in this paper we propose a novel spherical directly-connected antenna array (DCAA), which composes of multiple simple uniform planar arrays (sUPAs) placed over a spherical surface. All elements within each sUPA are directly connected. Compared to conventional arrays with hybrid analog/digital beamforming (HBF), DCAA significantly reduces hardware cost, improves energy focusing, and provides superior and uniform angular res olution for 3D space. These advantages make DCAA particularly suitable for integrated sensing and communication (ISAC) in low-altitude unmanned aerial vehicles (UAV) swarm scenarios, where targets may frequently move away from the boresight of traditional arrays, degrading both communication and sensing performance. Simulation results demonstrate that the proposed spherical DCAA achieves significantly better angular resolution and higher spectral efficiency than conventional array with HBF, highlighting its strong potential for UAV swarm ISAC systems.

3D Spherical Directly-Connected Antenna Array for Low-Altitude UAV Swarm ISAC

Abstract

Recently a novel multi-antenna architecture termed ray antenna array (RAA) was proposed, where several simple uniform linear arrays (sULAs) are arranged in a ray-like structure to enhance communication and sensing performance. By eliminating the need for phase shifters, it also significantly reduces hardware costs. However, RAA is prone to signal blockage and has no elevation angle resolution capability in three-dimensional (3D) scenarios. To address such issues, in this paper we propose a novel spherical directly-connected antenna array (DCAA), which composes of multiple simple uniform planar arrays (sUPAs) placed over a spherical surface. All elements within each sUPA are directly connected. Compared to conventional arrays with hybrid analog/digital beamforming (HBF), DCAA significantly reduces hardware cost, improves energy focusing, and provides superior and uniform angular res olution for 3D space. These advantages make DCAA particularly suitable for integrated sensing and communication (ISAC) in low-altitude unmanned aerial vehicles (UAV) swarm scenarios, where targets may frequently move away from the boresight of traditional arrays, degrading both communication and sensing performance. Simulation results demonstrate that the proposed spherical DCAA achieves significantly better angular resolution and higher spectral efficiency than conventional array with HBF, highlighting its strong potential for UAV swarm ISAC systems.
Paper Structure (18 sections, 7 theorems, 62 equations, 17 figures, 1 algorithm)

This paper contains 18 sections, 7 theorems, 62 equations, 17 figures, 1 algorithm.

Table of Contents

  1. Introduction
  2. System Model
  3. Spherical DCAA Architecture
  4. Array Response of Spherical DCAA
  5. sUPA Orientation Design and Spherical DCAA Implementation
  6. Spherical DCAA vs Conventional UPA
  7. Conventional UPA
  8. Angular Resolution Comparison
  9. Sensing Algorithm for Spherical DCAA-based ISAC
  10. Spherical DCAA-based ISAC
  11. Communication Model
  12. Sensing Model
  13. Sensing Algorithm Design
  14. Simulation Results
  15. Conclusion
  16. ...and 3 more sections

Key Result

Lemma 1

For a sUPA with orientation $\mathbf{u}_1',\mathbf{u}_2'$ and incoming wave vector $\mathbf{k}$, we have $\max\limits_{\mathbf{k}} |f(\mathbf{u}_1',\mathbf{u}_2',\mathbf{k})|=M^2$, and the maximum is achieved if and only if $\mathbf{R}^\mathrm{T}(\eta,\vartheta )\mathbf{k}=[1,0,0]^\mathrm{T}$ or eq

Figures (17)

  • Figure 1: An illustration of spherical DCAA-based bi-static ISAC for low-altitude UAV swarm.
  • Figure 2: (a) Illustration of sUPA in the proposed spherical DCAA, where all antenna elements of sUPA are separated by half wavelength and directly connected; (b) Rotate the sUPA with respect to $y$-axis and $z$-axis without self-spinning.
  • Figure 3: Null curves and beam pattern of the sUPA when $M=8$ and $(\eta,\vartheta) = (29^\circ,45^\circ)$. The null curves are plotted through solid lines and dashed lines representing different equations in \ref{['eq:null 1']}
  • Figure 4: The orientation of sUPAs $(\eta_{p,q},\vartheta_{q})$ according to equation \ref{['eq:etapq']}, where $M=8$.
  • Figure 5: The beam pattern of: (a) spherical DCAA; (b) conventional UPA with KPC-based HBF, and the envelope of beam pattern of: (c) spherical DCAA; (d) conventional UPA with KPC-based HBF.
  • ...and 12 more figures

Theorems & Definitions (8)

  • Lemma 1
  • Lemma 2
  • Lemma 3
  • Theorem 1
  • Lemma 4
  • Lemma 5
  • Definition 1
  • Theorem 2