{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,7]],"date-time":"2026-05-07T15:09:11Z","timestamp":1778166551403,"version":"3.51.4"},"reference-count":26,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2024,1,12]],"date-time":"2024-01-12T00:00:00Z","timestamp":1705017600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Youth Innovation Promotion Association of Chinese Academy of Sciences","award":["2021292"],"award-info":[{"award-number":["2021292"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The high-accuracy and high-stability space-based time system is necessary for satellite navigation systems to achieve high quality of service (QoS) on navigation and positioning in smart city applications. This paper proposes a precise and high-stability space-based time system established under the autonomous time scale of navigation satellites. The generation, maintenance, and transfer of high-precision space-based time references are researched. A centralized time comparison method based on the ALGOS algorithm conducts the two-way time comparison of the inter-satellite link. Specifically, using the relative clock difference observations of all links between satellites for a certain period of time, the clock difference, clock speed, and clock drift parameters of n\u22121 stars in a constellation of n stars relative to the same reference can be estimated simultaneously. Simulations are conducted on real collected data from the Beidou navigation systems when providing services to smart cities around the world. The simulation results show the high accuracy and stability of the proposed space-based time system under the autonomous time scale reference. Moreover, the clock offset monitoring arc coverage is much higher than the satellite clock offset obtained by the direct observation of the satellite and the anchor station. It proves the efficiency of the proposed space-based time system to be used for satellite clock offset modeling and prediction.<\/jats:p>","DOI":"10.3390\/s24020480","type":"journal-article","created":{"date-parts":[[2024,1,12]],"date-time":"2024-01-12T07:47:16Z","timestamp":1705045636000},"page":"480","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["A Precise and Stable Space-Based Time System for Navigation in Smart Cities"],"prefix":"10.3390","volume":"24","author":[{"given":"Shaoqian","family":"Li","sequence":"first","affiliation":[{"name":"Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 101408, China"},{"name":"University of Chinese Academy of Sciences, Beijing 101408, China"},{"name":"Innovation Academy for Microsatellites, Chinese Academy of Sciences, Beijing 101408, China"},{"name":"Shanghai Engineering Center for Microsatellites, Shanghai 201203, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Baojun","family":"Lin","sequence":"additional","affiliation":[{"name":"Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 101408, China"},{"name":"University of Chinese Academy of Sciences, Beijing 101408, China"},{"name":"Innovation Academy for Microsatellites, Chinese Academy of Sciences, Beijing 101408, China"},{"name":"Shanghai Engineering Center for Microsatellites, Shanghai 201203, China"},{"name":"Aerospace Information Research Institute, University of Chinese Academy of Sciences, Innovation Academy for Microsatellites, Shanghai Engineering Center for Microsatellites, ShanghaiTech University, Shanghai 201210, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2149-8798","authenticated-orcid":false,"given":"Rui","family":"Li","sequence":"additional","affiliation":[{"name":"University of Chinese Academy of Sciences, Beijing 101408, China"},{"name":"Innovation Academy for Microsatellites, Chinese Academy of Sciences, Beijing 101408, China"},{"name":"Shanghai Engineering Center for Microsatellites, Shanghai 201203, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xiaogong","family":"Hu","sequence":"additional","affiliation":[{"name":"Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Richang","family":"Dong","sequence":"additional","affiliation":[{"name":"Innovation Academy for Microsatellites, Chinese Academy of Sciences, Beijing 101408, China"},{"name":"Shanghai Engineering Center for Microsatellites, Shanghai 201203, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2024,1,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"34815","DOI":"10.1109\/ACCESS.2022.3162917","article-title":"A survey on laser space network: Terminals, links, and architectures","volume":"10","author":"Li","year":"2022","journal-title":"IEEE Access"},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Li, R., Lin, B., Liu, Y., Tan, S., Zhao, S., Dong, M., Lei, J., and Kong, L. 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