Near-Field Wideband Channel Estimation for Extremely Large-Scale RIS-Aided Communication Systems
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arXiv
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| Main Authors: | , , , |
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| Format: | Preprint |
| Published: |
2026
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| _version_ | 1866915883081793536 |
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| author | Zhi, Lanqing Wang, Hongwei Li, Lingxiang Chen, Zhi |
| author_facet | Zhi, Lanqing Wang, Hongwei Li, Lingxiang Chen, Zhi |
| contents | This paper studies wideband channel estimation for OFDM systems assisted by extremely large RIS (XL-RIS). Due to the large aperture of XL-RISs, the user equipment may operate in the near-field region, while the base station-XL-RIS link remains in the far field, leading to a cascaded channel with hybrid near-field and far-field characteristics. Moreover, wideband effects further complicate channel estimation in mmWave/THz systems. To address these challenges, we propose a frequency-independent orthogonal dictionary by augmenting the discrete Fourier transform (DFT) matrix with additional parameters, which enables an efficient representation of the wideband cascaded channel using a two-dimensional block-sparse structure. Based on this property, the considered channel estimation problem is effectively solved within a tailored compressed sensing framework. Simulation results demonstrate that the proposed method significantly outperforms conventional polar-domain channel estimation approaches in terms of estimation accuracy. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2603_21709 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Near-Field Wideband Channel Estimation for Extremely Large-Scale RIS-Aided Communication Systems Zhi, Lanqing Wang, Hongwei Li, Lingxiang Chen, Zhi Signal Processing This paper studies wideband channel estimation for OFDM systems assisted by extremely large RIS (XL-RIS). Due to the large aperture of XL-RISs, the user equipment may operate in the near-field region, while the base station-XL-RIS link remains in the far field, leading to a cascaded channel with hybrid near-field and far-field characteristics. Moreover, wideband effects further complicate channel estimation in mmWave/THz systems. To address these challenges, we propose a frequency-independent orthogonal dictionary by augmenting the discrete Fourier transform (DFT) matrix with additional parameters, which enables an efficient representation of the wideband cascaded channel using a two-dimensional block-sparse structure. Based on this property, the considered channel estimation problem is effectively solved within a tailored compressed sensing framework. Simulation results demonstrate that the proposed method significantly outperforms conventional polar-domain channel estimation approaches in terms of estimation accuracy. |
| title | Near-Field Wideband Channel Estimation for Extremely Large-Scale RIS-Aided Communication Systems |
| topic | Signal Processing |
| url | https://arxiv.org/abs/2603.21709 |