Title: Direct-to-Cell: A First Look into Starlink's Direct Satellite-to-Device Radio Access Network through Crowdsourced Measurements Show Chinese title

Title: 直接到终端：通过众包测量首次了解星链的直接卫星到设备无线接入网络

Abstract: Low Earth Orbit (LEO) satellite mega-constellations have recently emerged as a viable access solution for broadband services in underserved areas. In 2024, Direct Satellite-to-Device (DS2D) communications, which enable unmodified smartphones to connect directly to spaceborne base stations, entered large-scale beta testing, with Starlink globally leading deployments. This paper presents the first measurement study of commercial DS2D services. Using crowdsourced mobile network data collected in the U.S. between October 2024 and April 2025, our research derives evidence-based insights into the capabilities, limitations, and prospective evolution of DS2D technologies providing Supplemental Coverage from Space (SCS) services to expand existing mobile network connectivity. We observe a strong correlation between the number of satellites deployed and the expanding extension of observed measurements, concentrated in accessible but poorly covered areas by terrestrial networks, such as national parks and large low-density counties. The data reveal stable physical-layer value measurement throughout the observation period, with a lower median RSRP (24-dB difference) and a higher RSRQ (3 dB difference) compared to terrestrial networks, reflecting the SMS-only usage of the DS2D network during this period. Based on SINR measurements, we estimate the expected performance of the announced DS2D mobile data service to be around 4 Mbps per beam in outdoor conditions. We also discuss strategies to expand this capacity up to 12 Mbps in the future, depending on key regulatory decisions regarding satellite licenses, spectrum availability, and allowable radiated power levels. Show Chinese abstract

Abstract: 低地轨道（LEO）卫星巨型星座最近成为为服务不足地区提供宽带服务的可行解决方案。 在2024年， 直接卫星到设备（DS2D）通信使未经修改的智能手机能够直接连接到空间基站，进入了大规模测试阶段，Starlink在全球范围内率先部署。 本文介绍了对商业DS2D服务的首次测量研究。 使用在美国2024年10月至2025年4月期间收集的众包移动网络数据，我们的研究得出了关于DS2D技术能力、限制和未来演进的实证见解，这些技术为现有移动网络连接提供从太空补充覆盖（SCS）服务。 我们观察到部署的卫星数量与观测测量范围的扩展之间存在强烈相关性，这些测量集中在地面网络可访问但覆盖较差的区域，如国家公园和大型低密度县。 数据揭示了在整个观测期间稳定的物理层值测量，与地面网络相比，中位RSRP低24-dB，RSRQ高3-dB，反映了DS2D网络在此期间仅用于短信（SMS）使用。 基于SINR测量，我们估计宣布的DS2D移动数据服务的预期性能在户外条件下每波束约为4 Mbps。 我们还讨论了在未来扩大此容量至12 Mbps的策略，这取决于有关卫星许可证、频谱可用性和允许辐射功率水平的关键监管决策。