{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,25]],"date-time":"2026-02-25T18:12:15Z","timestamp":1772043135364,"version":"3.50.1"},"reference-count":41,"publisher":"MDPI AG","issue":"20","license":[{"start":{"date-parts":[[2022,10,13]],"date-time":"2022-10-13T00:00:00Z","timestamp":1665619200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003696","name":"Electronics and Telecommunications Research Institute","doi-asserted-by":"publisher","award":["22ZK1100"],"award-info":[{"award-number":["22ZK1100"]}],"id":[{"id":"10.13039\/501100003696","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Free space optical (FSO) communication can support various unmanned aerial vehicles\u2019 (UAVs) applications that require large capacity data transmission. In order to perform FSO communication between two terminals, it is essential to employ a pointing, acquisition, and tracking (PAT) system with an efficient and optimal performance. We report on the development of a common optical-path-based FSO communication system, tailored for applications in UAVs. The proposed system is equipped with a quadrant photodiode (QPD)-based PAT system without an additional beacon beam subsystem. The presented approach reduced the structural complexity and improved the tracking efficiency for the same size, weight, and power (SWaP). To achieve a robust FSO link in a dynamic UAV environment, the observability and controllability were obtained based on the linearized control according to the incident beam size on the QPD, which was verified by optical simulation and experiments. As a result, the QPD-based PAT system for implementing FSO links demonstrated an up to 4.25 times faster tracking performance. Moreover, the FSO link experimentally confirmed the 1.25 Gbps full-duplex error-free communication at a 50 m distance.<\/jats:p>","DOI":"10.3390\/s22207770","type":"journal-article","created":{"date-parts":[[2022,10,14]],"date-time":"2022-10-14T01:44:13Z","timestamp":1665711853000},"page":"7770","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":15,"title":["Tracking Efficiency Improvement According to Incident Beam Size in QPD-Based PAT System for Common Path-Based Full-Duplex FSO Terminals"],"prefix":"10.3390","volume":"22","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-3815-828X","authenticated-orcid":false,"given":"Siwoong","family":"Park","sequence":"first","affiliation":[{"name":"School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju 61005, Korea"},{"name":"Honam Research Center, Electronics and Telecommunications of Research Institute, 176-11 Cheomdan, Gwagi-ro, Buk-gu, Gwangju 61012, Korea"}]},{"given":"Chan Il","family":"Yeo","sequence":"additional","affiliation":[{"name":"Honam Research Center, Electronics and Telecommunications of Research Institute, 176-11 Cheomdan, Gwagi-ro, Buk-gu, Gwangju 61012, Korea"}]},{"given":"Young Soon","family":"Heo","sequence":"additional","affiliation":[{"name":"Honam Research Center, Electronics and Telecommunications of Research Institute, 176-11 Cheomdan, Gwagi-ro, Buk-gu, Gwangju 61012, Korea"}]},{"given":"Ji Hyoung","family":"Ryu","sequence":"additional","affiliation":[{"name":"Honam Research Center, Electronics and Telecommunications of Research Institute, 176-11 Cheomdan, Gwagi-ro, Buk-gu, Gwangju 61012, Korea"}]},{"given":"Hyun Seo","family":"Kang","sequence":"additional","affiliation":[{"name":"Honam Research Center, Electronics and Telecommunications of Research Institute, 176-11 Cheomdan, Gwagi-ro, Buk-gu, Gwangju 61012, Korea"}]},{"given":"Dong-Seon","family":"Lee","sequence":"additional","affiliation":[{"name":"School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju 61005, Korea"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9633-5574","authenticated-orcid":false,"given":"Jae-Hyung","family":"Jang","sequence":"additional","affiliation":[{"name":"Department of Energy Engineering, KENTECH Institute of Energy Materials and Devices, Korea Institute of Energy Technology, Naju 58330, Korea"}]}],"member":"1968","published-online":{"date-parts":[[2022,10,13]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"218","DOI":"10.1109\/MCOM.2017.1600735","article-title":"FSO-based vertical backhaul\/fronthaul framework for 5G+ wireless networks","volume":"56","author":"Alzenad","year":"2018","journal-title":"IEEE Commun. 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