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Unlike prior STA\u2013DL approaches, the proposed method explicitly addresses two key challenges: atmospheric turbulence in terrestrial FSO links and Doppler\u2010induced carrier\u2010frequency offset (CFO) in high\u2010mobility LEO channels. The framework integrates spectral temporal averaging (STA) with three deep learning architectures\u2014a feed\u2010forward neural network (STA\u2010FNN), a super\u2010resolution convolutional neural network (STA\u2010SRCNN), and a denoising convolutional neural network (STA\u2010DNCNN)\u2014in a two\u2010stage process where STA supplies a coarse, noise\u2010resilient estimate that is refined by the deep network to capture nonlinear distortions and rapid channel variations. A pilot tone\u2013based CFO synchronization module, incorporated ahead of the DL stage, provides explicit Doppler mitigation, a critical feature rarely combined with learning\u2010based estimators. Extensive simulations demonstrate that STA\u2010SRCNN and STA\u2010DNCNN achieve state\u2010of\u2010the\u2010art performance, delivering NMSE of , BER of , and EVM of 8% for 64\u2010QAM at 11 dB SNR in terrestrial FSO channels, while maintaining similar robust performance in LEO scenarios, as compared to conventional LS and STA. These results confirm that the proposed hybrid STA\u2010DL framework offers a computationally efficient and practically deployable solution that outperforms classical least\u2010squares and MMSE estimators for next\u2010generation high\u2010throughput optical satellite\u00a0communications.<\/jats:p>","DOI":"10.1049\/cmu2.70148","type":"journal-article","created":{"date-parts":[[2026,3,20]],"date-time":"2026-03-20T08:46:53Z","timestamp":1773996413000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Hybrid STA With FNN and CNN Models for Robust Channel Estimation in Turbulent FSO and Doppler\u2010Affected OFDM transmission for LEO Satellite Communication"],"prefix":"10.1049","volume":"20","author":[{"given":"Saad","family":"Rustum","sequence":"first","affiliation":[{"name":"Faculty of Computer Science &amp; Enggineering GIK Institute of Enggineering Sciences &amp; Technology Khyber Pakhtunkhwa Pakistan"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9115-9716","authenticated-orcid":false,"given":"Usman","family":"Habib","sequence":"additional","affiliation":[{"name":"Faculty of Computer Science &amp; Enggineering GIK Institute of Enggineering Sciences &amp; Technology Khyber Pakhtunkhwa Pakistan"}]},{"given":"Salman","family":"Ahmed","sequence":"additional","affiliation":[{"name":"Faculty of Computer Science &amp; Enggineering GIK Institute of Enggineering Sciences &amp; Technology Khyber Pakhtunkhwa Pakistan"}]},{"given":"Muhammad","family":"Ahmad","sequence":"additional","affiliation":[{"name":"Faculty of Computer Science &amp; Enggineering GIK Institute of Enggineering Sciences &amp; Technology Khyber Pakhtunkhwa Pakistan"}]},{"given":"Muhammad","family":"Ijaz","sequence":"additional","affiliation":[{"name":"Department of Engineering Manchester Metropolitan University Manchester UK"}]}],"member":"265","published-online":{"date-parts":[[2026,3,20]]},"reference":[{"issue":"3","key":"e_1_2_11_2_1","first-page":"1594","article-title":"Satellite Communications in the 5G Era: A survey","volume":"22","author":"Lin X.","year":"2020","journal-title":"IEEE Communications Surveys & Tutorials"},{"key":"e_1_2_11_3_1","doi-asserted-by":"publisher","DOI":"10.1109\/COMST.2023.3347145"},{"issue":"1","key":"e_1_2_11_4_1","first-page":"57","article-title":"Free Space Optical Communication: A Survey","volume":"19","author":"Kaushal H.","year":"2017","journal-title":"IEEE Communications Surveys & Tutorials"},{"key":"e_1_2_11_5_1","unstructured":"S.Alatawi S. 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