With the rapid growth of the low-altitude economy, the demand for cellular-enabled low-altitude wireless networks (LAWN) is rising significantly. The three-dimensional mobility of drones will lead to frequent handovers (HOs) in cellular networks, while traditional reference signal received power (RSRP)-based criteria may fail to capture the dynamic environment, causing redundant HOs or HO failures. To address this issue and motivated by the underutilization of sensing information in conventional HO mechanisms, we propose a novel HO activation criterion for drone systems that integrates both sensing parameters provided by integrated sensing and communication (ISAC) signals and RSRP. First, we construct an ISAC signal model tailored for low-altitude scenarios and derive the Cram\'er--Rao lower bound for sensing distance estimation. Subsequently, we propose a novel joint HO criterion that extends the conventional RSRP-based method by integrating sensing information from ISAC signals, enabling more reliable HOs in dynamic drone environments. Simulation results show that the joint HO criterion outperforms the baseline RSRP-based criterion under different signal-to-noise ratio (SNR) and sensing pilot ratio conditions. Particularly, when the SNR exceeds 0dB and the sensing pilot ratio is 20%, the proposed joint HO criterion reduces the average HO region length by 75.20% and improves the activation probability by 76.31%.

翻译：随着低空经济的快速发展，对蜂窝赋能的低空无线网络（LAWN）的需求显著增长。无人机的三维移动性将导致蜂窝网络中频繁发生切换（HO），而传统的基于参考信号接收功率（RSRP）的准则可能无法捕捉动态环境，从而引发冗余切换或切换失败。为解决此问题，并受传统切换机制中感知信息未充分利用的启发，我们提出了一种面向无人机系统的新型切换激活准则，该准则融合了集成感知与通信（ISAC）信号提供的感知参数和RSRP。首先，我们构建了针对低空场景定制的ISAC信号模型，并推导了感知距离估计的克拉美-罗下界。随后，我们提出了一种新颖的联合切换准则，该准则通过集成来自ISAC信号的感知信息，扩展了传统的基于RSRP的方法，从而在动态无人机环境中实现更可靠的切换。仿真结果表明，在不同的信噪比（SNR）和感知导频比例条件下，联合切换准则的性能优于基于RSRP的基线准则。特别是当SNR超过0dB且感知导频比例为20%时，所提出的联合切换准则将平均切换区域长度降低了75.20%，并将激活概率提高了76.31%。