Demystifying Starlink Network Performance under Vehicular Mobility with Dynamic Beam Switching

TL;DR

This work investigates Starlink network performance under vehicular mobility and transient obstructions, revealing that UTs can perform multiple dynamic beam switches within a 15-second window to maintain connectivity. It introduces a mobility-aware satellite identification method that leverages obstruction maps, UT orientation (via unit quaternion $q$ and compensated heading $\delta'$), and frame alignment to detect dynamic beam switching and explain throughput and latency variations using UT diagnostics and satellite ephemeris data. The study demonstrates that mobility amplifies beam-switching events, with stationary obstructed cases showing 17.9% FOV obstruction and mobile cases contributing up to 45.18% of outage time, while angular-identification accuracy degrades from $\approx2.37^\circ$ to $\approx5.44^\circ$ under motion. These findings enable more accurate modeling of end-to-end Starlink performance in mobility scenarios and motivate the design of mobility-aware transport protocols and constellation-scenario simulations.

Abstract

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.

Figures (11)

• Figure 1: Starlink UT obstruction maps obtained from the gRPC interface in different scenarios. Black: Unexplored region. White: Obstruction-free FOV. Red: Obstructed area.
• Figure 2: Obstructed Starlink UT obstruction maps presented in different reference frames, as viewed within the mobile application and retrieved from the gRPC interface. (a)-(c): UT A; (d)-(f): UT B. Both UTs share the same rev3_proto2 hardware model.
• Figure 3: Overview of measurement setup
• Figure 4: The compensated heading degree $\delta^\prime$ converted from $\mathbf{q}$ remains stable when the UT is near level ($\theta \xrightarrow{} 0$)
• Figure 5: When the UT is in motion, the $\oplus$ operation can return multiple pixels between obstruction maps