{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T01:24:12Z","timestamp":1760232252785,"version":"build-2065373602"},"reference-count":24,"publisher":"MDPI AG","issue":"21","license":[{"start":{"date-parts":[[2022,10,23]],"date-time":"2022-10-23T00:00:00Z","timestamp":1666483200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Ministry of Science and Technology (Taiwan)","award":["MOST 109 2221 E 194 030"],"award-info":[{"award-number":["MOST 109 2221 E 194 030"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>This paper focuses on the hardware components of smartphones, namely, the use of displays and cameras in mobile devices as transmitters and receivers to establish a near-field multiple-input\u2013multiple-output (MIMO) visible light communication (VLC) system. Based on the relationship between the grayscale values of transmitted and received signals, the physical channel responses are detected and approximated with a high-order regression to obtain the channel gain. With the constraint of bit numbers in the MIMO VLC system, an integer-type water-filling scheme was designed for bit allocation to improve transmission efficiency. The physical examinations show that bit error rate (BER) reduction can be 26.4% with Gaussian noise of 30 dB and detected channel gain compared with the equal bit allocation. The optimization of the simulation was confirmed with the bit assignments in real cases.<\/jats:p>","DOI":"10.3390\/s22218117","type":"journal-article","created":{"date-parts":[[2022,10,24]],"date-time":"2022-10-24T10:09:23Z","timestamp":1666606163000},"page":"8117","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Optimization of Bit Allocation for Spatial Multiplexing in MIMO VLC System with Smartphones"],"prefix":"10.3390","volume":"22","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-3775-5469","authenticated-orcid":false,"given":"Chang-Ming","family":"Lee","sequence":"first","affiliation":[{"name":"Department of Communications Engineering, National Chung Cheng University, Chiayi 621301, Taiwan"},{"name":"Advanced Institute of Manufacturing with High-Tech Innovations, Chiayi 621301, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Bo-Hung","family":"Li","sequence":"additional","affiliation":[{"name":"Department of Communications Engineering, National Chung Cheng University, Chiayi 621301, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Chang-Chin","family":"Chiang","sequence":"additional","affiliation":[{"name":"Department of Communications Engineering, National Chung Cheng University, Chiayi 621301, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2022,10,23]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"118","DOI":"10.1109\/MWC.001.1900488","article-title":"A Speculative Study on 6G","volume":"27","author":"Tariq","year":"2020","journal-title":"IEEE Wirel. 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