eprintid: 10184978 rev_number: 8 eprint_status: archive userid: 699 dir: disk0/10/18/49/78 datestamp: 2024-01-08 14:18:01 lastmod: 2024-12-20 07:10:04 status_changed: 2024-01-08 14:18:01 type: article metadata_visibility: show sword_depositor: 699 creators_name: Clark, Kari A creators_name: Zhou, Zichuan creators_name: Liu, Zhixin title: Clock synchronizing radio access networks to picosecond precision using optical clock distribution and clock phase caching ispublished: pub divisions: UCL divisions: B04 divisions: C05 divisions: F46 note: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. abstract: Performing positioning of future mobile devices using trilateration through radio access networks would provide a robust alternative to currently used global navigation satellite systems. However, the positioning accuracy is strongly dependent on the time synchronization accuracy of the antennas used as location reference points. Consequently, achieving sub-30 cm positioning accuracies requires the synchronization of radio access network antennas to sub-nanosecond accuracy. Here we show a clock phase synchronization and optical clock signal distribution approach to clock synchronization in radio access networks that achieves 0.98-ps root-mean-square precision clock synchronization, in a real-time field-trial demonstration on 37.6-km dark fiber, with optical clock frequency synchronization and clock phase caching operating using 25.6-Gb/s commercial transceivers. We quantify the clock synchronization performance of our approach using standard metrics, including time deviation (TDEV) and mean time interval error (MTIE). Furthermore, we estimate the impact of varying the phase update rate used in clock phase caching on the clock synchronization performance of our approach. Through our two combined approaches, we explore a route towards achieving sub-nanosecond clock synchronization in radio access networks. date: 2024-01-01 date_type: published publisher: Optica Publishing Group official_url: http://dx.doi.org/10.1364/jocn.500459 oa_status: green full_text_type: other language: eng primo: open primo_central: open_green verified: verified_manual elements_id: 2135363 doi: 10.1364/jocn.500459 lyricists_name: Clark, Kari lyricists_name: Liu, Zhixin lyricists_id: KACLA99 lyricists_id: ZLIUB50 actors_name: Clark, Kari actors_id: KACLA99 actors_role: owner full_text_status: public publication: Journal of Optical Communications and Networking volume: 16 number: 1 pagerange: A89-A89 issn: 1943-0620 citation: Clark, Kari A; Zhou, Zichuan; Liu, Zhixin; (2024) Clock synchronizing radio access networks to picosecond precision using optical clock distribution and clock phase caching. Journal of Optical Communications and Networking , 16 (1) A89-A89. 10.1364/jocn.500459 <https://doi.org/10.1364/jocn.500459>. Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/10184978/1/Clark2023.pdf