{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T09:19:27Z","timestamp":1785403167325,"version":"3.56.0"},"reference-count":28,"publisher":"MDPI AG","issue":"14","license":[{"start":{"date-parts":[[2026,7,11]],"date-time":"2026-07-11T00:00:00Z","timestamp":1783728000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100002338","name":"Ministry of Education of the People's Republic of China","doi-asserted-by":"publisher","award":["202510512011"],"award-info":[{"award-number":["202510512011"]}],"id":[{"id":"10.13039\/501100002338","id-type":"DOI","asserted-by":"publisher"}]},{"award":["202510512011"],"award-info":[{"award-number":["202510512011"]}],"id":[{"id":"https:\/\/ror.org\/01mv9t934","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>To address the stringent requirements of 6G industrial Internet of Things (IoT) and ultra-dense networks on spectral efficiency, hardware cost, and transmission reliability, this paper investigates waveguide index modulation based on the pinching-antenna system (PASS), a promising flexible multiple-input multiple-output (MIMO) architecture featuring large-scale reconfigurability and robust line-of-sight (LoS) link establishment. A two-stage sparse transmission framework is proposed, where a Simulated Annealing-based Constrained Discrete Optimization (SA-CDO) algorithm is first employed to optimize pinching-antenna (PA) positions and construct a near-orthogonal equivalent channel dictionary for inter-waveguide interference suppression. Subsequently, an Orthogonal Least Squares-based Constellation-Constrained (OLS-CC) detector is developed to jointly recover active waveguide indices and modulation symbols with low computational complexity. Monte Carlo simulations demonstrate that the proposed scheme consistently outperforms conventional antenna index modulation under both LoS and Rician fading channels across the entire SNR range. The SA-CDO optimization significantly reduces the bit error rate (BER), while the OLS-CC detector further improves sparse recovery accuracy and reduces the detection complexity from exponential to polynomial order. These results provide valuable insights for the design of highly reliable 6G IoT communication systems.<\/jats:p>","DOI":"10.3390\/s26144407","type":"journal-article","created":{"date-parts":[[2026,7,13]],"date-time":"2026-07-13T08:05:31Z","timestamp":1783929931000},"page":"4407","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Reconfigurable Transmission Design for PASS-MIMO via Waveguide Indexing"],"prefix":"10.3390","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0009-0004-3783-775X","authenticated-orcid":false,"given":"Yaxian","family":"Wang","sequence":"first","affiliation":[{"name":"Manchester Metropolitan Joint Institute, Hubei University, Wuhan 430062, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3130-4747","authenticated-orcid":false,"given":"Songjie","family":"Yang","sequence":"additional","affiliation":[{"name":"National Key Laboratory of Wireless Communications, University of Electronic Science and Technology of China, Chengdu 611731, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Juhong","family":"Peng","sequence":"additional","affiliation":[{"name":"School of Artificial Intelligence, Hubei University, Wuhan 430062, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,11]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Bazzi, A., Gast, F., Liu, F., Jin, S., Fettweis, G., and Chafii, M. (2026). From Coverage to Sensing: ISAC Meets FR3. IEEE Commun. Mag., 1\u20137.","DOI":"10.1109\/MCOM.001.2500787"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"957","DOI":"10.1109\/OJCOMS.2020.3010270","article-title":"6G Wireless Communication Systems: Applications, Requirements, Technologies, Challenges, and Research Directions","volume":"1","author":"Chowdhury","year":"2020","journal-title":"IEEE Open J. Commun. Soc."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"5296","DOI":"10.1109\/JSYST.2020.2975653","article-title":"RF Chain Reduction for MIMO Systems: A Hardware Prototype","volume":"14","author":"Gong","year":"2020","journal-title":"IEEE Syst. J."},{"key":"ref_4","unstructured":"Irshad, A., Bj\u00f6rnson, E., Kosasih, A., and Petrov, V. (2026). Performance Evaluation of Movable Antenna Arrays in Wideband Multi-User MIMO Systems. arXiv."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1950","DOI":"10.1109\/TWC.2020.3037595","article-title":"Fluid Antenna Systems","volume":"20","author":"Wong","year":"2021","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"990","DOI":"10.1109\/TCCN.2020.2992604","article-title":"Reconfigurable Intelligent Surfaces for Wireless Communications: Principles, Challenges, and Opportunities","volume":"6","author":"ElMossallamy","year":"2020","journal-title":"IEEE Trans. Cogn. Commun. Netw."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"190","DOI":"10.1109\/MCOM.001.2500037","article-title":"Pinching-antenna systems: Architecture designs, opportunities, and outlook","volume":"64","author":"Liu","year":"2025","journal-title":"IEEE Commun. Mag."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"92","DOI":"10.1109\/TCOMM.2025.3618726","article-title":"On the Performance of Uplink Pinching Antenna Systems (PASS)","volume":"74","author":"Hou","year":"2026","journal-title":"IEEE Trans. Commun."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"4881","DOI":"10.1109\/TCOMM.2026.3658289","article-title":"Pinching-Antenna Systems (PASS): A Tutorial","volume":"74","author":"Liu","year":"2026","journal-title":"IEEE Trans. Commun."},{"key":"ref_10","first-page":"6789","article-title":"Flexible-Antenna Systems: A Pinching-Antenna Perspective","volume":"73","author":"Liu","year":"2025","journal-title":"IEEE Trans. Commun."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"13904","DOI":"10.1109\/TCOMM.2025.3621049","article-title":"Modeling and beamforming optimization for pinching-antenna systems","volume":"73","author":"Wang","year":"2025","journal-title":"IEEE Trans. Commun."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"3500","DOI":"10.1109\/LWC.2025.3596094","article-title":"Frequency-selective modeling and analysis for OFDM-integrated wideband pinching-antenna systems","volume":"14","author":"Xiao","year":"2025","journal-title":"IEEE Wirel. Commun. Lett."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1471","DOI":"10.1109\/LCOMM.2025.3566299","article-title":"Array Gain for Pinching-Antenna Systems (PASS)","volume":"29","author":"Ouyang","year":"2025","journal-title":"IEEE Commun. Lett."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"2160","DOI":"10.1109\/TCOMM.2025.3636083","article-title":"Pinching-Antenna Systems (PASS): Power Radiation Model and Optimal Beamforming Design","volume":"74","author":"Xu","year":"2026","journal-title":"IEEE Trans. Commun."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"2924","DOI":"10.1109\/TCOMM.2025.3649683","article-title":"PASS-Based Multi-User Communications: Capacity Characterization and Configuration Strategy","volume":"74","author":"Xiao","year":"2026","journal-title":"IEEE Trans. Commun."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"3421","DOI":"10.1109\/TWC.2026.3664320","article-title":"Hybrid Pinching Antenna Systems: Architecture and Beamforming Design","volume":"25","author":"Chen","year":"2026","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"5872","DOI":"10.1109\/COMST.2026.3674222","article-title":"Generalized Pinching-Antenna Systems: A Tutorial on Principles, Design Strategies, and Future Directions","volume":"28","author":"Xu","year":"2026","journal-title":"IEEE Commun. Surv. Tuts."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"44","DOI":"10.1109\/MSP.2024.3444195","article-title":"Index modulation for integrated sensing and communications: A signal processing perspective","volume":"41","author":"Elbir","year":"2024","journal-title":"IEEE Signal Process. Mag."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Sui, Z., Liu, Z., Musavian, L., Yang, L.-L., and Hanzo, L. (2025). Generalized spatial modulation aided affine frequency division multiplexing. arXiv.","DOI":"10.1109\/TWC.2025.3613062"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"12148","DOI":"10.1109\/TVT.2025.3550275","article-title":"Polarization-Aided Multi-User Spatial Modulation","volume":"74","author":"Xie","year":"2025","journal-title":"IEEE Trans. Veh. Technol."},{"key":"ref_21","first-page":"43742","article-title":"Energy-Efficient Index and Code Index Modulations for Spread CPM Signals in Internet of Things","volume":"12","author":"Yuan","year":"2025","journal-title":"IEEE IoT J."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Yang, S., Li, Y., Xiao, Y., Guan, Y.L., Lei, X., and Ding, Z. (2025). Pinching-antenna-assisted index modulation: Channel modeling, transceiver design, and performance analysis. arXiv.","DOI":"10.1109\/TWC.2026.3654385"},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Xiao, J., Wang, J., and Liu, Y. (2025). Channel Estimation for Pinching-Antenna Systems (PASS). arXiv.","DOI":"10.1109\/LCOMM.2025.3575166"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1203","DOI":"10.1109\/LWC.2024.3366173","article-title":"Fluid Antenna Index Modulation Communications","volume":"13","author":"Chen","year":"2024","journal-title":"IEEE Wirel. Commun. Lett."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"9701","DOI":"10.1109\/TWC.2024.3364712","article-title":"Index Modulation for Fluid Antenna-Assisted MIMO Communications: System Design and Performance Analysis","volume":"23","author":"Zhu","year":"2024","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"4941","DOI":"10.1109\/TCOMM.2023.3280209","article-title":"Double RIS-Assisted MIMO Systems Over Spatially Correlated Rician Fading Channels and Finite Scatterers","volume":"71","author":"Le","year":"2023","journal-title":"IEEE Trans. Commun."},{"key":"ref_27","unstructured":"Golub, G.H., and Van Loan, C.F. (2013). Matrix Computations, Johns Hopkins University Press. [4th ed.]."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"265","DOI":"10.1023\/A:1006504901164","article-title":"Tackling Real-Coded Genetic Algorithms: Operators and Tools for Behavioural Analysis","volume":"12","author":"Herrera","year":"1998","journal-title":"Artif. Intell. Rev."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/26\/14\/4407\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,15]],"date-time":"2026-07-15T04:18:32Z","timestamp":1784089112000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/26\/14\/4407"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,7,11]]},"references-count":28,"journal-issue":{"issue":"14","published-online":{"date-parts":[[2026,7]]}},"alternative-id":["s26144407"],"URL":"https:\/\/doi.org\/10.3390\/s26144407","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,7,11]]}}}