{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T02:26:06Z","timestamp":1760235966219,"version":"build-2065373602"},"reference-count":37,"publisher":"MDPI AG","issue":"20","license":[{"start":{"date-parts":[[2021,10,17]],"date-time":"2021-10-17T00:00:00Z","timestamp":1634428800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The Internet of Things (IoT) leads the era of interconnection, where numerous sensors and devices are being introduced and interconnected. To support such an amount of data traffic, wireless communication technologies have to overcome available spectrum shortage and complex fading channels. The transform domain communication system (TDCS) is a cognitive anti-interference communication system with a low probability of detection and dynamic spectrum sensing and accessing. However, the non-continuous and asymmetric spectrum brings new challenges to the traditional TDCS block-type pilot, which uses a series of discrete symbols in the time domain as pilots. Low efficiency and poor adaptability in fast-varying channels are the main drawbacks for the block-type pilot in TDCS. In this study, a frequency domain non-uniform pilot design method was proposed with intersecting, skewing, and edging of three typical non-uniform pilots. Some numerical examples are also presented with multipath model COST207RAx4 to verify the proposed methods in the bit error ratio and the mean square error. Compared with traditional block-type pilot, the proposed method can adapt to the fast-varying channels, as well as the non-continuous and asymmetric spectrum conditions with much higher efficiency.<\/jats:p>","DOI":"10.3390\/s21206880","type":"journal-article","created":{"date-parts":[[2021,10,17]],"date-time":"2021-10-17T23:25:15Z","timestamp":1634513115000},"page":"6880","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Efficient Non-Uniform Pilot Design for TDCS"],"prefix":"10.3390","volume":"21","author":[{"given":"Cheng","family":"Chang","sequence":"first","affiliation":[{"name":"China Academy of Launch Vehicle Technology, Beijing 100076, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lina","family":"Feng","sequence":"additional","affiliation":[{"name":"Beijing Institute of Astronautical Systems Engineering, Beijing 100076, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hui","family":"Zhou","sequence":"additional","affiliation":[{"name":"China Academy of Launch Vehicle Technology, Beijing 100076, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zilong","family":"Zhao","sequence":"additional","affiliation":[{"name":"China Academy of Launch Vehicle Technology, Beijing 100076, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xin","family":"Gu","sequence":"additional","affiliation":[{"name":"China Academy of Launch Vehicle Technology, Beijing 100076, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,10,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"711","DOI":"10.23940\/ijpe.21.08.p7.711721","article-title":"Secure ECG Signal Transmission for Smart Healthcare","volume":"17","author":"Harinee","year":"2021","journal-title":"IJPE"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"790","DOI":"10.1109\/TR.2021.3062045","article-title":"Transfer Learning Promotes 6G Wireless Communications: Recent Advances and Future Challenges","volume":"70","author":"Wang","year":"2021","journal-title":"IEEE Trans. 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