Time synchronization is a critical component in network operation and management, and it is also required by Ultra-Reliable, Low-Latency Communications (URLLC) in next-generation wireless systems such as those of 5G, 6G, and Open RAN. In this context, we design and implement AraSync as an end-to-end time synchronization system in the ARA wireless living lab to enable advanced wireless experiments and applications involving stringent time constraints. We make use of Precision Time Protocol (PTP) at different levels to achieve synchronization accuracy in the order of nanoseconds. Along with fiber networks, AraSync enables time synchronization across the AraHaul wireless x-haul network consisting of long-range, high-capacity mmWave and microwave links. In this paper, we present the detailed design and implementation of AraSync, including its hardware and software components and the PTP network topology. Further, we experimentally characterize the performance of AraSync from spatial and temporal dimensions. Our measurement and analysis of the clock offset and mean path delay show the impact of the wireless channel and weather conditions on the PTP synchronization accuracy.

翻译：时间同步是网络运维与管理的关键组成部分，也是5G、6G及开放式无线接入网（Open RAN）等下一代无线系统中超可靠低时延通信（URLLC）的必要条件。在此背景下，我们设计并实现了AraSync，作为ARA无线生活实验室中的端到端时间同步系统，以支持涉及严格时间约束的先进无线实验与应用。我们在不同层级采用精确时间协议（PTP），实现了纳秒量级的同步精度。结合光纤网络，AraSync能够在由长距离、高容量毫米波与微波链路组成的AraHaul无线x-haul网络中实现跨域时间同步。本文详细阐述了AraSync的设计与实现，包括其硬件与软件组件以及PTP网络拓扑。此外，我们从空间与时间维度对AraSync的性能进行了实验表征。通过对时钟偏移与平均路径延迟的测量与分析，我们揭示了无线信道及天气条件对PTP同步精度的影响。