Browsing by Author "Chen, Hui"

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    6G Radio Requirements to Support Integrated Communication, Localization, and Sensing
    (2022) Wymeersch, Henk; Parssinen, Aarno; Abrudan, Traian E.; Wolfgang, Andreas; Haneda, Katsuyuki; Sarajlic, Muris; Leinonen, Marko E.; Keskin, Musa Furkan; Chen, Hui; Lindberg, Simon; Kyosti, Pekka; Svensson, Tommy; Yang, Xinxin; Department of Electronics and Nanoengineering; Katsuyuki Haneda Group; Chalmers University of Technology; University of Oulu; Qamcom Research and Technology AB; Ericsson AB; Lucent
    6G will be characterized by extreme use cases, not only for communication, but also for localization, and sensing. The use cases can be directly mapped to requirements in terms of standard key performance indicators (KPIs), such as data rate, latency, or localization accuracy. The goal of this paper is to go one step further and map these standard KPIs to requirements on signals, on hardware architectures, and on deployments. Based on this, system solutions can be identified that can support several use cases simultaneously. Since there are several ways to meet the KPIs, there is no unique solution and preferable configurations will be discussed.
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    Bi-Static Sensing for Near-Field RIS Localization
    (2023-01-11) Ghazalian, Reza; Keykhosravi, Kamran; Chen, Hui; Wymeersch, Henk; Jäntti, Riku; Department of Communications and Networking; Communication Engineering; Chalmers University of Technology
    We address the localization of a reconfigurable intelligent surface (RIS) for a single-input single-output multi-carrier system using bi-static sensing between a fixed transmitter and a fixed receiver. Due to the deployment of RISs with a large dimension, near-field (NF) scenarios are likely to occur, especially for indoor applications, and are the focus of this work. We first derive the Cramér-Rao bounds (CRBs) on the estimation error of the RIS position and orientation and the time of arrival (TOA) for the path transmitter-RIS-receiver. We propose a multi-stage low-complexity estimator for RIS localization purposes. In this proposed estimator, we first perform a line search to estimate the TOA. Then, we use the far-field approximation of the NF signal model to implicitly estimate the angle of arrival and the angle of departure at the RIS center. Finally, the RIS position and orientation estimate are refined via a quasi-Newton method. Simulation results reveal that the proposed estimator can attain the CRBs. We also investigate the effects of several influential factors on the accuracy of the proposed estimator like the RIS size, transmitted power, system bandwidth, and RIS position and orientation.
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    Mechanisms of Strain-Induced Interfacial Strengthening of Wet-Spun Filaments
    (AMERICAN CHEMICAL SOCIETY, 2022-04-13) Guo, Tianyu; Wan, Zhangmin; Yu, Yan; Chen, Hui; Wang, Zhifeng; Li, Dagang; Song, Junlong; Rojas, Orlando J.; Jin, Yongcan; Department of Bioproducts and Biosystems; Bio-based Colloids and Materials; Nanjing Forestry University; University of British Columbia; Yangzhou University
    We investigate the mechanism of binding of dopamine-conjugated carboxymethyl cellulose (DA-CMC) with carbon nanotubes (CNTs) and the strain-induced interfacial strengthening that takes place upon wet drawing and stretching filaments produced by wet-spinning. The filaments are known for their tensile strength (as high as 972 MPa and Young modulus of 84 GPa) and electrical conductivity (241 S cm-1). The role of axial orientation in the development of interfacial interactions and structural changes, enabling shear load bearing, is studied by molecular dynamics simulation, which further reveals the elasto-plasticity of the system. We propose that the reversible torsion of vicinal molecules and DA-CMC wrapping around CNTs are the main contributions to the interfacial strengthening of the filaments. Such effects play important roles in impacting the properties of filaments, including those related to electrothermal heating and sensing. Our findings contribute to a better understanding of high aspect nanoparticle assembly and alignment to achieve high-performance filaments.