In the last few years, considerable research efforts have focused on measuring and improving Starlink network performance, especially for user terminals (UTs) in stationary scenarios. However, the performance of Starlink networks in mobility settings, particularly with frequent changes in the UT's orientation, and the impact of environmental factors, such as transient obstructions, has not been thoroughly studied, leaving gaps in understanding the causes of performance degradation. Recently, researchers have started identifying the communicating satellites to evaluate satellite selection strategies and the impact on network performance. However, existing Starlink satellite identification methods only work in stationary, obstruction-free scenarios, as they do not account for UT mobility, obstructions or detect dynamic beam switching events. In this paper, we reveal that the UT can perform multiple dynamic beam switching attempts to connect to different satellites when the UT-satellite link is degraded. This degradation can occur either due to the loss of line-of-sight (LoS) from changes in the FOV or obstructions, or due to poor signal quality, extending UT-satellite handovers beyond the well-known 15-second regular handover interval. We propose a mobility-aware Starlink satellite identification method that detects dynamic beam switching events, and plausibly explain network performance using UT's diagnostic data and connected satellite information. Our findings demystifies the mobile Starlink network performance degradations, which is crucial to enhance the end-to-end performance of transport layer protocols and in diverse application scenarios.

翻译：近年来，大量研究工作聚焦于测量和改进星链网络性能，尤其针对静止场景下的用户终端。然而，星链网络在移动环境中的性能表现——特别是用户终端朝向频繁变化的情况——以及环境因素（如瞬时遮挡）的影响尚未得到深入研究，导致对性能下降原因的理解存在空白。近期，研究者开始通过识别通信卫星来评估卫星选择策略及其对网络性能的影响。然而，现有的星链卫星识别方法仅适用于静止、无遮挡场景，因其未考虑用户终端的移动性、遮挡效应或动态波束切换事件的检测。本文揭示：当用户终端与卫星间的链路质量下降时，用户终端可执行多次动态波束切换尝试以连接不同卫星。链路质量下降可能源于视场角变化或遮挡导致的视距传输中断，也可能源于信号质量恶化，这使得用户终端-卫星切换过程可能超出已知的15秒常规切换间隔。我们提出一种支持移动感知的星链卫星识别方法，能够检测动态波束切换事件，并基于用户终端的诊断数据与连接卫星信息合理解释网络性能。本研究揭示了移动场景下星链网络性能下降的内在机制，这对于提升传输层协议的端到端性能及拓展多样化应用场景具有重要意义。