AI 中文总结
研究低空ISAC系统，针对传统天线阵列问题，采用球形直接连接天线阵列。通过表征其感知性能，制定优化问题并开发新框架，该阵列在多方面优于传统UPA，展现出在未来低空ISAC系统中的潜力。
AI 中文摘要
低空经济的安全发展需求使稳健的低空空域监测变得前所未有的重要。作为6G关键发展趋势之一的信息感知与通信一体化（ISAC）为低空经济提供了潜在解决方案。然而，传统天线阵列存在三维感知覆盖有限和高仰角时角度分辨率下降的问题。本文研究了由最近提出的球形直接连接天线阵列（DCAA）支持的低空ISAC系统。通过在球面上精心部署多个简单均匀平面阵列（sUPA），无需任何移相器，球形DCAA具有全三维覆盖、卓越且均匀的角度分辨率、增强的能量聚焦和低硬件成本等优势。本文首先从感知信噪比（SNR）、区域平均检测概率以及仰角和方位角估计的克拉美罗下界（CRLB）方面表征了球形DCAA的感知性能。然后，制定了一个低空ISAC优化问题，以在满足地面用户通信服务质量要求的同时，在规定的空域区域内最大化最坏情况下的感知SNR。为有效解决这个混合整数非凸问题，我们开发了一种新颖的基于贪婪的联合阵列选择和波束成形优化框架。仿真结果表明，球形DCAA在感知覆盖、角度估计精度和通信-感知SNR权衡方面明显优于传统均匀平面阵列（UPA），突出了其在未来低空ISAC系统中的潜力。
英文摘要
The safety development requirements of low-altitude economy (LAE) renders the robust low-altitude airspace monitoring critical important than ever before. Integrated sensing and communication (ISAC) as one of the key development trends of 6G provides potential solutions for the LAE. However, conventional antenna arrays suffer from limited three-dimensional (3D) sensing coverage and degraded angular resolution at high elevation angles. To address these challenges, this paper investigates low-altitude ISAC systems enabled by the recently proposed spherical directly-connected antenna array (DCAA). By carefully deploying multiple simple uniform planar arrays (sUPAs) over a spherical surface, without relying on any phase shifter, spherical DCAA enjoys advantages of full 3D coverage, superior and uniform angular resolution, enhanced energy-focusing and low hardware cost. In this paper, we first characterizes the sensing performance of the spherical DCAA, in terms of the sensing signal-to-noise ratio (SNR), area average probability of detection, and Cramér-Rao lower bounds (CRLBs) for both elevation and azimuth angle estimation. Then, a low-altitude ISAC optimization problem is formulated to maximize the worst-case sensing SNR over a prescribed aerial region while satisfying the communication quality-of-service requirements of ground users. To effective solve this mixed-integer non-convex problem, we develop a novel greed-based joint array selection and beamforming optimization framework. Simulation results demonstrate that spherical DCAA significantly outperforms conventional UPA in terms of sensing coverage, angle estimation accuracy, and communication-sensing SNR tradeoff, highlighting its potential for future low-altitude ISAC systems.
