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Wireless communications assisted by reconfigurable intelligent surfaces : an electromagnetic model

Abstract : The emergence of smart radio environment (SRE) as a new paradigm that challenges the status quo in wireless communication has motivated the use of metasurface-based reconfigurable intelligent surface (RIS) to improve the performance limits in wireless communication systems. The main focus of this thesis is the modeling of reconfigurable intelligent surfaces (RIS)-aided communication systems using electromagnetic based methods.Chapter 1 introduces the concept of smart radio environment. We also give the definition of RIS and how RIS can be used in context of SRE. To give some historical perspectives, we also discuss several important milestone papers throughout the development of research activities that lead to the current state of the art.Chapter 2 introduces theoretical concepts that are necessary to understand the results in the subsequent chapters. This chapter is divided into two parts. The first part discusses the metasurfaces modeling where we move from a physics-based microscopic description of a metasurface and introduces a macroscopic representation for it, which is shown to be suitable for application in wireless communications. The second part introduces several analytical approaches that allow us to compute the EM field at any point of a given volume that contains the metasurface.Chapter 3 provides a performance comparison between RISs operating as anomalous reflectors and a decode-and-forward relaying scheme that is representative of competing candidate technologies to realize SREs. The comparison is qualitative and covers multitude metrics. Furthermore, a quantitative comparison in terms of achievable data rates is presented. In particular, the numerical results show that sufficiently large RISs can outperform relay-aided systems in terms of data rate, while reducing the implementation complexity.Chapter 4 proposes an electromagnetic-based analytical characterization of the free-space path-loss of a wireless link in the presence of a RIS that is modeled as a two-dimensional homogenized metasurface made of sub-wavelength scattering elements and that operate either in reflection or transmission mode. The analytical method of physical optics is employed. Closed-form expressions are also obtained in two asymptotic regimes that are representative of far-field and near-field deployments. Based on the proposed approach, the impact of several design parameters and operating regimes is unveiled.Finally, Chapter 5 summarizes the main findings of the thesis and discusses possible future directions that are worth investigating to unlock the full potential of RIS and bring it into practice.
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Submitted on : Friday, June 25, 2021 - 3:16:09 PM
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  • HAL Id : tel-03271277, version 1

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Fadil Danufane. Wireless communications assisted by reconfigurable intelligent surfaces : an electromagnetic model. Networking and Internet Architecture [cs.NI]. Université Paris-Saclay, 2021. English. ⟨NNT : 2021UPASG038⟩. ⟨tel-03271277⟩

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