Providing reliable communication for unmanned aerial vehicles (UAVs) via existing cellular networks is crucial for enabling the rapid growth of the low-altitude economy. However, UAV jittering significantly degrades communication quality due to induced beam misalignment. Inspired by recent advances in integrated sensing and communication, we propose a novel two-stage active sensing-assisted communication framework tailored for ground-to-UAV links with jittering. Specifically, two schemes are conceived to leverage sensing for enhancing communication performance, namely the communication-oriented scheme and the sensing-oriented scheme. For the sensing-oriented scheme, deterministic signals are employed in the first stage to facilitate angle-of-arrival (AoA) acquisition at the UAV side, followed by pure communication service in the second stage by using the estimated AoA. In contrast, the communication-oriented scheme employs Gaussian information-bearing signals throughout both stages, with AoA estimation relying on Gaussian random signals. For both schemes, we provide maximum likelihood estimators for AoA, along with analytical results characterizing the Cramér-Rao bound. To capture the performance limit, closed-form expressions for the achievable rates of the two schemes are derived, unveiling a fundamental tradeoff between sensing and communication quality across the two stages by tuning the time allocated to the first stage. The optimal time allocation that maximizes the overall rate is obtained in semi-closed-form. Based on these results, we unveil a sufficient condition under which the communication-oriented scheme outperforms the sensing-oriented scheme, which admits an interesting threshold-based structure. Asymptotic analysis demonstrates that the performance loss of the proposed schemes relative to the jitter-free upper bound approaches zero in the high transmit power regime.

翻译：为无人机通过现有蜂窝网络提供可靠通信，是支撑低空经济快速发展的关键。然而，无人机抖动会引发波束对准偏差，严重降低通信质量。受集成感知与通信技术最新进展启发，我们提出一种面向地面-无人机抖动链路的新型两阶段主动感知辅助通信框架。具体而言，设计了两种利用感知增强通信性能的方案，即通信导向方案和感知导向方案。对于感知导向方案，第一阶段采用确定性信号辅助无人机端获取到达角，第二阶段利用估计的到达角进行纯通信服务。相比之下，通信导向方案在两阶段均使用高斯信息承载信号，到达角估计依赖于高斯随机信号。针对两种方案，我们给出了到达角的最大似然估计器，并推导了表征克拉美罗界的解析结果。为刻画性能极限，推导了两方案可达速率的闭式表达式，揭示了通过调节第一阶段时间分配实现感知与通信质量间的根本性权衡。以半闭式形式给出了最大化总速率的最优时间分配。基于这些结果，我们揭示了通信导向方案优于感知导向方案的充分条件，该条件具有有趣的阈值结构。渐近分析表明，在高发射功率条件下，所提方案相对于无抖动理想上界的性能损失趋近于零。