Dovelos, KonstantinosAssimonis, Stylianos D.Ngo, Hien QuocBellalta, BorisMatthaiou, Michail2023-03-062021Dovelos K, Assimonis SD, Ngo HQ, Bellalta B, Matthaiou M. Intelligent reflecting surfaces at terahertz bands: channel modeling and analysis. In: 2021 IEEE International Conference on Communications Workshops (ICC Workshops): proceedings; 2021 Jun 14-23; Montreal, Canada. [Piscataway]: IEEE, 2021. [6 p.]. DOI: 10.1109/ICCWorkshops50388.2021.94738902164-7038http://hdl.handle.net/10230/56044Comunicació presentada a 2021 IEEE International Conference on Communications Workshops (ICC Workshops), celebrat del 14 al 23 de juny de 2021 de manera virtual.An intelligent reflecting surface (IRS) at terahertz (THz) bands is expected to have a massive number of reflecting elements to compensate for the severe propagation losses. However, as the IRS size grows, the conventional far-field assumption starts becoming invalid and the spherical wavefront of the radiated waves should be taken into account. In this work, we consider a spherical wave channel model and pursue a comprehensive study of IRS-aided multiple-input multiple-output (MIMO) in terms of power gain and energy efficiency (EE). Specifically, we first analyze the power gain under beamfocusing and beamforming, and show that the latter is suboptimal even for multiple meters away from the IRS. To this end, we derive an approximate, yet accurate, closed-form expression for the loss in the power gain under beamforming. Building on the derived model, we next show that an IRS can significantly improve the EE of MIMO when it operates in the radiating near-field and performs beamfocusing. Numerical results corroborate our analysis and provide novel insights into the design and performance of IRS-assisted THz communication.application/pdfeng© 2021 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. http://dx.doi.org/10.1109/ICCWorkshops50388.2021.9473890info:eu-repo/semantics/conferenceObjecthttp://dx.doi.org/10.1109/ICCWorkshops50388.2021.9473890MetersClosed-form solutionsArray signal processingSurface wavesConferencesPropagation lossesMIMOinfo:eu-repo/semantics/openAccess