{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,14]],"date-time":"2026-01-14T17:01:41Z","timestamp":1768410101341,"version":"3.49.0"},"reference-count":43,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2023,6,1]],"date-time":"2023-06-01T00:00:00Z","timestamp":1685577600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia","award":["PNURSP2023R137"],"award-info":[{"award-number":["PNURSP2023R137"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>A radio is adaptive if it can autonomously analyze the communications environment and instantly modify its settings to achieve the best possible efficiency. In orthogonal frequency division multiplexing (OFDM) transmissions, identifying the space frequency block coding (SFBC) category utilized is one of the most important tasks of an adaptive receiver. Previous approaches to this problem did not take into consideration the fact that real systems typically suffer from transmission defects. This study offers a novel maximum likelihood recognizer capable of distinguishing between SFBC OFDM waveforms in the context of inphase and quadrature phase differences (IQDs). The theoretical findings show that IQDs arising from the transmitter and recipient can be combined with channel paths to generate so-called effective channel paths. The conceptual examination demonstrates that the outlined maximum likelihood strategy of the SFBC recognition and effective channel estimation processes is implemented by an expectation maximization tool utilizing the error control decoders\u2019 soft outputs. The simulations results reveal that the suggested strategy delivers a much greater recognition accuracy than the typical approaches outlined in the comparable literature. At a signal-to-noise ratio (SNR) of 14 dB, for example, the proposed approach achieves a bit error rate (BER) of 0.00002, which is very close to the case of perfect estimation and compensation for IQDs, outperforming the previous reported works which achieved BERs of 0.01 and 0.02.<\/jats:p>","DOI":"10.3390\/s23115267","type":"journal-article","created":{"date-parts":[[2023,6,2]],"date-time":"2023-06-02T02:16:48Z","timestamp":1685672208000},"page":"5267","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["SFBC Recognition over Orthogonal Frequency Division Multiplexing Schemes in the Presence of Inphase and Quadrature Phase Discrepancies for Cognitive Radio Applications"],"prefix":"10.3390","volume":"23","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-2105-7239","authenticated-orcid":false,"given":"Mohamed","family":"Marey","sequence":"first","affiliation":[{"name":"Smart Systems Engineering Laboratory, College of Engineering, Prince Sultan University, P.O. Box 66833, Riyadh 11586, Saudi Arabia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ahmed","family":"Sedik","sequence":"additional","affiliation":[{"name":"Smart Systems Engineering Laboratory, College of Engineering, Prince Sultan University, P.O. Box 66833, Riyadh 11586, Saudi Arabia"},{"name":"Department of the Robotics and Intelligent Machines, Faculty of Artificial Intelligence, Kafrelsheikh University, Kafrelsheikh 33516, Egypt"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7388-8990","authenticated-orcid":false,"given":"Hala","family":"Mostafa","sequence":"additional","affiliation":[{"name":"Department of Information Technology, College of Computer and Information Sciences, Princess Nourah bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi Arabia"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,6,1]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"5504011","DOI":"10.1109\/TIM.2021.3109737","article-title":"Design and Implementation of Blind Modulation Classification for Asynchronous MIMO-OFDM System","volume":"70","author":"Pathy","year":"2021","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"6738","DOI":"10.1109\/TVT.2022.3159254","article-title":"MIMO-OFDM Modulation Classification Using Three-Dimensional Convolutional Network","volume":"71","author":"Nguyen","year":"2022","journal-title":"IEEE Trans. Veh. Technol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"4946","DOI":"10.1109\/TII.2020.3016958","article-title":"Intelligent Signal Classification in Industrial Distributed Wireless Sensor Networks Based Industrial Internet of Things","volume":"17","author":"Liu","year":"2021","journal-title":"IEEE Trans. Ind. Inform."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"3020","DOI":"10.1109\/TIM.2018.2868556","article-title":"Design and Implementation of a Tree-Based Blind Modulation Classification Algorithm for Multiple-Antenna Systems","volume":"68","author":"Gupta","year":"2019","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"745","DOI":"10.1109\/LWC.2020.3042384","article-title":"Soft-Information Assisted Modulation Recognition for Reconfigurable Radios","volume":"10","author":"Marey","year":"2021","journal-title":"IEEE Wirel. Commun. Lett."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"116994","DOI":"10.1109\/ACCESS.2021.3106235","article-title":"Probabilistic Spectrum Sensing Based on Feature Detection for 6G Cognitive Radio: A Survey","volume":"9","author":"Ivanov","year":"2021","journal-title":"IEEE Access"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"2017","DOI":"10.1109\/LWC.2021.3090938","article-title":"Iterative Modulation Classification Algorithm for Two-Path Successive Relaying Systems","volume":"10","author":"Marey","year":"2021","journal-title":"IEEE Wirel. Commun. Lett."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"1027","DOI":"10.1109\/LCOMM.2022.3149284","article-title":"Blind Modulation Classification Under Uncertain Noise Conditions: A Multitask Learning Approach","volume":"26","author":"Qiao","year":"2022","journal-title":"IEEE Commun. Lett."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"82","DOI":"10.1109\/JSAC.2021.3126088","article-title":"Signal Processing-Based Deep Learning for Blind Symbol Decoding and Modulation Classification","volume":"40","author":"Hanna","year":"2022","journal-title":"IEEE J. Sel. Areas Commun."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"521","DOI":"10.1109\/LWC.2015.2451174","article-title":"Blind Modulation Classification for Alamouti STBC System With Transmission Impairments","volume":"4","author":"Marey","year":"2015","journal-title":"IEEE Wirel. Commun. Lett."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"13","DOI":"10.25103\/jestr.094.03","article-title":"Preliminary BER Study of a TC-OFDM System Operating Under Noisy Conditions","volume":"9","author":"Chronopoulos","year":"2016","journal-title":"J. Eng. Sci. Technol. Rev."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"5281","DOI":"10.1109\/TVT.2020.2981935","article-title":"Blind Modulation Classification for Asynchronous OFDM Systems Over Unknown Signal Parameters and Channel Statistics","volume":"69","author":"Gupta","year":"2020","journal-title":"IEEE Trans. Veh. Technol."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"308","DOI":"10.1109\/LWC.2017.2774809","article-title":"Soft-Information Aided Channel Estimation With IQ Imbalance for Alternate-Relaying OFDM Cooperative Systems","volume":"7","author":"Marey","year":"2018","journal-title":"IEEE Wirel. Commun. Lett."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"4580","DOI":"10.1109\/TVT.2020.2976954","article-title":"Performance Analysis of Dual-Hop Relaying With I\/Q Imbalance and Additive Hardware Impairment","volume":"69","author":"Gao","year":"2020","journal-title":"IEEE Trans. Veh. Technol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1304","DOI":"10.1109\/TWC.2019.2891649","article-title":"Joint Channel Estimation and Tx\/Rx I\/Q Imbalance Compensation for GFDM Systems","volume":"18","author":"Cheng","year":"2019","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"8483","DOI":"10.1109\/TVT.2020.2995848","article-title":"Joint Compensation of Transmitter and Receiver I\/Q Imbalances for SC-FDE Systems","volume":"69","author":"Cheng","year":"2020","journal-title":"IEEE Trans. Veh. Technol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"111718","DOI":"10.1109\/ACCESS.2021.3101845","article-title":"RF Impairments in Wireless Transceivers: Phase Noise, CFO, and IQ Imbalance\u2014A Survey","volume":"9","author":"Mohammadian","year":"2021","journal-title":"IEEE Access"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"2118","DOI":"10.1109\/ACCESS.2022.3233941","article-title":"Coded Assisted Transmit and Receive IQ Mismatch Compensation With Channel Estimation for AF Cooperative OFDM Systems","volume":"11","author":"Marey","year":"2023","journal-title":"IEEE Access"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"389","DOI":"10.1007\/s11082-022-04446-5","article-title":"Automatic Modulation Classification in Optical Wireless Communication Systems Based on Cancellable Biometric Concepts","volume":"55","author":"Mohamed","year":"2023","journal-title":"Opt. Quantum Electron."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"343","DOI":"10.1007\/s11082-022-04454-5","article-title":"Modulation Format Recognition Using CNN-based Transfer Learning Models","volume":"55","author":"Mohamed","year":"2023","journal-title":"Opt. Quantum Electron."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Mortada, B., El-Shafai, W., Zahran, O., El-Rabaie, E.M., and El-Samie, F.E.A. Fan-beam Projection Based Modulation Classification for Optical Systems with Phase Noise Effect. J. Opt., 2023.","DOI":"10.1007\/s12596-023-01112-1"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"e4623","DOI":"10.1002\/ett.4623","article-title":"Automatic Modulation Classification with 2D Transforms and Convolutional Neural Network","volume":"33","author":"Ghanem","year":"2022","journal-title":"Trans. Emerg. Telecommun. Technol."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"11","DOI":"10.1109\/LCOMM.2019.2953229","article-title":"Blind Recognition of LDPC Codes Over Candidate Set","volume":"24","author":"Wu","year":"2020","journal-title":"IEEE Commun. Lett."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"33619","DOI":"10.1109\/ACCESS.2019.2904718","article-title":"Parameter Identification of Reed-Solomon Codes Based on Probability Statistics and Galois Field Fourier Transform","volume":"7","author":"Liu","year":"2019","journal-title":"IEEE Access"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"2420","DOI":"10.1109\/TCOMM.2013.042313.120629","article-title":"Fourth-Order Statistics for Blind Classification of Spatial Multiplexing and Alamouti Space-Time Block Code Signals","volume":"61","author":"Eldemerdash","year":"2013","journal-title":"IEEE Trans. Commun."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"2574","DOI":"10.1109\/TWC.2012.041612.111488","article-title":"Classification of Space-time Block Codes Based on Second-order Cyclostationarity with Transmission Impairments","volume":"11","author":"Marey","year":"2012","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Marey, M., Dobre, O.A., and Inkol, R. (2012, January 10\u201315). Cyclostationarity-Based Blind Classification of STBCs for Cognitive Radio Systems. Proceedings of the IEEE International Conference on Communications, Ottawa, ON, Canada.","DOI":"10.1109\/ICC.2012.6363735"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"2159","DOI":"10.1109\/TVT.2014.2335415","article-title":"Classification of STBC Systems over Frequency-selective Channels","volume":"64","author":"Marey","year":"2015","journal-title":"IEEE Trans. Veh. Technol."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"117","DOI":"10.1109\/TWC.2016.2619676","article-title":"Automatic Identification of Space-Frequency Block Coding for OFDM Systems","volume":"16","author":"Marey","year":"2017","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"1290","DOI":"10.1109\/TSP.2009.2036062","article-title":"Blind Recognition of Linear Space Time Block Codes: A Likelihood-Based Approach","volume":"58","author":"Choqueuse","year":"2010","journal-title":"IEEE Trans. Signal Process."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"3526","DOI":"10.1109\/TWC.2008.070364","article-title":"Hierarchical Space-Time Block Code Recognition Using Correlation Matrices","volume":"58","author":"Choqueuse","year":"2008","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"79994","DOI":"10.1109\/ACCESS.2021.3084845","article-title":"Automatic Space-Time Block Code Recognition Using Convolutional Neural Network With Multi-Delay Features Fusion","volume":"9","author":"Zhang","year":"2021","journal-title":"IEEE Access"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"1554","DOI":"10.1109\/TCOMM.2014.030214.130875","article-title":"Blind STBC Identification for Multiple Antenna OFDM Systems","volume":"62","author":"Marey","year":"2014","journal-title":"IEEE Trans. Commun."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"972","DOI":"10.1109\/TWC.2014.2363093","article-title":"Blind Identification of SM and Alamouti STBC-OFDM Signals","volume":"14","author":"Eldemerdash","year":"2015","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"21336","DOI":"10.1109\/ACCESS.2022.3152191","article-title":"STBC Identification for Multi-User Uplink SC-FDMA Asynchronous Transmissions Exploiting Iterative Soft Information Feedback of Error Correcting Codes","volume":"10","author":"Marey","year":"2022","journal-title":"IEEE Access"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"35643","DOI":"10.1109\/ACCESS.2022.3161618","article-title":"Power of Error Correcting Codes for SFBC-OFDM Classification Over Unknown Channels","volume":"10","author":"Marey","year":"2022","journal-title":"IEEE Access"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"1513","DOI":"10.1109\/LWC.2022.3177638","article-title":"Cognitive Radios Equipped With Modulation and STBC Recognition Over Coded Transmissions","volume":"11","author":"Marey","year":"2022","journal-title":"IEEE Wirel. Commun. Lett."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"1456","DOI":"10.1109\/18.771146","article-title":"Space-Time Block Codes From Orthogonal Designs","volume":"9","author":"Tarokh","year":"1999","journal-title":"IEEE Trans. Inf. Theory"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"657","DOI":"10.1109\/LSP.2008.2004517","article-title":"Code-Aided Channel Tracking and Frequency Offset-Phase Noise Elimination for Multi-Carrier Systems","volume":"15","author":"Marey","year":"2008","journal-title":"IEEE Signal Process. Lett."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"661","DOI":"10.1109\/TCOMM.2004.826353","article-title":"Embedding Carrier Phase Recovery Into Iterative Decoding of Turbo-Coded Linear Modulations","volume":"52","author":"Lottici","year":"2004","journal-title":"IEEE Trans. Commun."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"1319","DOI":"10.1007\/s11277-015-3055-1","article-title":"Performance of Turbo Coded OFDM Under the Presence of Various Noise Types","volume":"87","author":"Chronopoulos","year":"2016","journal-title":"J. Wirel. Pers. Commun."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"3500","DOI":"10.1109\/TWC.2019.2914687","article-title":"Blind Identification of SFBC-OFDM Signals Based on the Central Limit Theorem","volume":"18","author":"Gao","year":"2019","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"9619","DOI":"10.1109\/TVT.2018.2859761","article-title":"Blind Identification of SFBC-OFDM Signals Using Subspace Decompositions and Random Matrix Theory","volume":"67","author":"Gao","year":"2018","journal-title":"IEEE Trans. Veh. Technol."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/23\/11\/5267\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T19:47:16Z","timestamp":1760125636000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/23\/11\/5267"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,6,1]]},"references-count":43,"journal-issue":{"issue":"11","published-online":{"date-parts":[[2023,6]]}},"alternative-id":["s23115267"],"URL":"https:\/\/doi.org\/10.3390\/s23115267","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2023,6,1]]}}}