Physics of Wave Processes and Radio SystemsPhysics of Wave Processes and Radio Systems1810-31892782-294XPovolzhskiy State University of Telecommunications and Informatics1042410.18469/1810-3189.2022.25.2.67-72Research ArticleThe effect of fast relay fading and frequency mismatch of the frequencies of the receiving and transmitting channels on the characteristics of the OFDM signalEliseevSergey N.<p>Doctor of Technical Sciences, professor of the Department of Theory of Electrical Circuits, Moscow Technical University of Communications and Informatics, Moscow, Russia.</p>
<p><em>Research interests</em>: digital signal processing, mobile communications, television and audio broadcasting.</p>fgupnrsnr@yandex.ruFilimonovaLyudmila N.<p>postgraduate student, engineer of the Department of Radio Electronic Systems, Povolzhskiy State University of Telecommunications and Informatics, Samara, Russia. In 2019, she graduated from the Povolzhskiy State University of Telecommunications and Informatics magistracy with honors in the field of training «Infocommunication technologies and communication systems».</p>
<p><em>Research interests</em>: nanotechnology, methods and means of digital signal processing and their application in radio communication and radio broadcasting and television systems.</p>lyudmila.trifonova.2012@mail.ruhttps://orcid.org/0000-0001-6761-8292Moscow Technical University of Communications and InformaticsPovolzhskiy State University of Telecommunications and Informatics25062022252677225062022Copyright © 2022, Eliseev S.N., Filimonova L.N.2022<p>In this paper, we consider the negative simultaneous effect of fast relay fading in the channel and mutual frequency shifts of subcarriers between the transmitting and receiving sides of the channel, causing violation of orthogonality between the signals of individual subchannels of OFDM system. Violation of orthogonality is manifested in the appearance of mutual interference signal at the receiving end of the channel in each OFDM subchannel. The paper evaluates the joint effect of fast fading and frequency shifts on the magnitude of the transient interference between subchannels and investigates in sufficient detail the manifestation of transient interference between individual subchannels caused by orthogonality violations each of the two factors cited separately. In this paper, we consider the simultaneous effect of both factors and their influence on the value of the interchannel transient interference.</p>системы беспроводной связичастотные сдвиги поднесущих OFDMбыстрые релеевские замирания, межканальная переходная помехаwireless communication systemscarrier frequence offsetfast Rayleigh fadingDoppler speadinginter-channel interference[Wang T. et al. Performance degradation of OFDM systems due to Doppler spreading. IEEE Transactions on Wireless Communications, 2006, vol. 5, no. 6, pp. 1422–1430.][Li Y., Stuber G. Orthogonal Frequency Division Multiplexing for Wireless Communications (Signals and Communication Technology). Berlin: Springer, 2006, pp. 19–46.][Robertson P., Kaiser S. The effects of Doppler spreads in OFDM(A) mobile radio systems. Gateway to 21st Century Communications Village. VTC 1999-Fall. IEEE VTS 50th Vehicular Technology Conference, 1999, vol. 1, pp. 329–333. DOI: https://doi.org/10.1109/VETECF.1999.797150][Li Y., Cimini L.J. Interchannel interference of OFDM in mobile radio channels. Globecom ‘00 – IEEE. Global Telecommunications Conference. Conference Record, 2000, vol. 2, pp. 706–710. DOI: https://doi.org/10.1109/GLOCOM.2000.891231][Kumar S. BER analysis of OFDM digital communication systems with improved ICI cancellation technique. International Journal of Intelligent Systems and Applications, 2014, vol. 6, no. 4, pp. 56–62. DOI: https://doi.org/10.5815/ijisa.2014.04.06][Martin-Vega F., Gomez G. Low-complexity pilot-based frequency-domain channel estimation for ICI mitigation in OFDM systems. Electronics, 2021, vol. 10, no. 12, pp. 1–16. DOI: https://doi.org/10.3390/electronics10121404][Vlachos E. et al. Adaptive windowing for ICI mitigation in vehicular communications. IEEE Wireless Communications Letters, 2018, vol. 7, no. 6, pp. 974–977. DOI: https://doi.org/10.1109/LWC.2018.2842226][Eliseev S.N. Estimation of the power of interchannel interference of an OFDM signal in a channel with fast fading. T-Comm: Telekommunikatsii i transport, 2017, vol. 11, no. 4, pp. 59–63. (In Russ.)][Lin K.-Y., Lin H.-P., Tseng M.-C. An equivalent channel time variation mitigation schefme for ICI reduction in high-mobility OFDM systems. IEEE Transactions on Broadcasting, 2012, vol. 58, no. 3, pp. 472–479. DOI: https://doi.org/10.1109/TBC.2012.2197450][Rehman N., Lei Z., Hammad M. ICI cancellation in OFDM systems by frequency offset reduction. Journal of Information Engineering and Applications, 2014, vol. 4, no. 9, pp. 1–10. URL: https://www.iiste.org/Journals/index.php/JIEA/article/view/15501]