Beamformer design for large-dimension reconfigurable intelligent surface (RIS) is investigated. The challenge arises from the expanded near-field of RIS where its beam-forming gain is, in general, distance-dependent due to near-field diffraction. To gain more insights into this effect, we first analyze the performance of conventional collimated beamforming using Fresnel integrals and compare it with that of focused beamforming. Then, a two-step beamforming scheme is proposed. The principle of the proposed scheme is to divide the RIS into multiple subarrays followed by steering the sub-beams of the individual subarrays to focus. Providing proper subarray size, the proposed scheme retains the low complexity of collimated beamforming and achieves a near-optimal performance, as shown both analytically and numerically.


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    Title :

    Two-Step Beamforming Scheme for Large-Dimension Reconfigurable Intelligent Surface


    Contributors:
    Li, Xiang (author) / Wang, Xin (author) / Hou, Xiaolin (author) / Chen, Lan (author) / Suyama, Satoshi (author)


    Publication date :

    2022-06-01


    Size :

    1232756 byte





    Type of media :

    Conference paper


    Type of material :

    Electronic Resource


    Language :

    English