{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,18]],"date-time":"2026-06-18T15:56:58Z","timestamp":1781798218945,"version":"3.54.5"},"reference-count":39,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2019,5,22]],"date-time":"2019-05-22T00:00:00Z","timestamp":1558483200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"This research was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government (MSIT)","award":["2018R1A4A1023826"],"award-info":[{"award-number":["2018R1A4A1023826"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Entropy"],"abstract":"<jats:p>In this paper, we consider a     2 \u00d7 2     space-time line coded (STLC) system having two-transmit and two-receive antennas. To improve the secrecy rate of the STLC system, in which an illegitimate receiver eavesdrops the information delivered from the STLC transmitter to the STLC receiver, we propose an artificial noise (AN) injection method. By exploiting the STLC structure, a novel AN for the STLC is designed and its optimal power loading factor is derived. Numerical results verify that the proposed secure STLC systems with the designed AN injection and the power control method can significantly improve the secrecy rate compared to the conventional STLC systems. It is observed that the proposed method is more effective if there is a significant gap between the main-channel and the eavesdropper-channel gains.<\/jats:p>","DOI":"10.3390\/e21050515","type":"journal-article","created":{"date-parts":[[2019,5,23]],"date-time":"2019-05-23T03:22:03Z","timestamp":1558581723000},"page":"515","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":22,"title":["Artificial Noise Injection and Its Power Loading Methods for Secure Space-Time Line Coded Systems"],"prefix":"10.3390","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9551-1123","authenticated-orcid":false,"given":"Jingon","family":"Joung","sequence":"first","affiliation":[{"name":"School of Electrical and Electronics Engineering, Chung-Ang University, Seoul 06974, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5433-2241","authenticated-orcid":false,"given":"Jihoon","family":"Choi","sequence":"additional","affiliation":[{"name":"School of Electronics and Information Engineering, Korea Aerospace University, Gyeonggi-do 10540, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4485-9592","authenticated-orcid":false,"given":"Bang Chul","family":"Jung","sequence":"additional","affiliation":[{"name":"Department of Electronics Engineering, Chungnam National University, Daejeon 34134, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sungwook","family":"Yu","sequence":"additional","affiliation":[{"name":"School of Electrical and Electronics Engineering, Chung-Ang University, Seoul 06974, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2019,5,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1355","DOI":"10.1002\/j.1538-7305.1975.tb02040.x","article-title":"The wire-tap channel","volume":"54","author":"Wyner","year":"1975","journal-title":"Bell Syst. 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