The direct-to-device (D2D) satellite network is an important 6G evolution direction to enable seamless ubiquitous connectivity. However, the network faces critical handover challenges due to high satellite mobility and wide beam footprints. Conventional handover strategies, mostly designed for terrestrial networks, may encounter excessive co-channel interference (CCI) and service degradation in the satellite environments. To address the issue, this paper introduces a novel handover optimization method to perform dynamic adjustment of an important parameter called elevation angle threshold (EAT) from an interference-aware perspective. Explicitly, we first analyze the trade-off between satellite visibility and CCI. Then, we propose a numerical algorithm to determine the optimal EAT that can achieve seamless coverage with CCI. We validate our method using a customized D2D LEO satellite network simulator in the Network Simulator (NS-3). The results demonstrate that the EAT optimization significantly reduces packet loss and hence enhances handover reliability. The work highlights the importance of interference-aware handover design for improving service continuity in future D2D satellite networks.

翻译：直接到设备（D2D）卫星网络是实现无缝泛在连接的重要6G演进方向。然而，由于卫星高速移动和波束覆盖范围广，该网络面临关键的切换挑战。主要为地面网络设计的传统切换策略在卫星环境中可能遭遇严重的同信道干扰（CCI）和服务质量下降。为解决此问题，本文从干扰感知的视角，提出一种新颖的切换优化方法，用于动态调整一个称为仰角阈值（EAT）的重要参数。具体而言，我们首先分析了卫星可见性与同信道干扰之间的权衡关系。随后，我们提出一种数值算法来确定能够实现带同信道干扰无缝覆盖的最优仰角阈值。我们使用网络仿真器（NS-3）中定制的D2D低地球轨道卫星网络仿真器验证了我们的方法。结果表明，仰角阈值优化显著降低了丢包率，从而提升了切换可靠性。本工作强调了干扰感知的切换设计对于提升未来D2D卫星网络服务连续性的重要性。