Near-Field Beamforming for Large Intelligent Surfaces

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Volume Title
Conference article in proceedings
Date
2022
Major/Subject
Mcode
Degree programme
Language
en
Pages
7
1367-1373
Series
2022 IEEE 33rd Annual International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC 2022, IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, Volume 2022-September
Abstract
In this paper, we propose a novel near-field beamforming (BF) design with a Large Intelligent Surface (LIS) that is implemented as a discretized 2D-array. We first investigate the definitions of the near-field and far-field regions, and determine the Fraunhofer distance of the LIS, which scales up linearly in the surface-area of the LIS. Hence, a user-equipment (UE) can enter the near-field of a LIS in practice. In addition to Fraunhofer distance, we further derive the Fresnel near-field region where both amplitude and angle variations are negligible, as long as the distance from the UE to the LIS is larger than a threshold, which only scales up linearly in the diameter of LIS. Therefore, in the majority region of near-field, only phase variations worsen the the quality of received signal and result in significant array-gain losses. Motivated by this observation, we further propose a two-step near-field BF design that can effectively recover the array-gain losses in Fresnel near-field, and is fully compatiblewith a conventional far-field BF.
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Publisher Copyright: © 2022 IEEE.
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Citation
Hu , S , Ilter , M C & Wang , H 2022 , Near-Field Beamforming for Large Intelligent Surfaces . in 2022 IEEE 33rd Annual International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC 2022 . IEEE International Symposium on Personal, Indoor and Mobile Radio Communications , vol. 2022-September , IEEE , pp. 1367-1373 , IEEE International Symposium on Personal, Indoor and Mobile Radio Communications , Virtual, Online , Japan , 12/09/2022 . https://doi.org/10.1109/PIMRC54779.2022.9977582