Abstract
Extremely large-scale multiple-input-multiple-output (XL-MIMO) at millimeter-wave (mmWave) and terahertz (THz) bands plays an important role in supporting extreme high beamforming gain as well as ultra-wideband spectrum resources. Unfortunately, accurate wideband XL-MIMO channel estimation suffers from a new challenge called the near-field beam split effect. Prior studies either neglect the accurate near-field channel model or fail to exploit the beam split effect, resulting in poor channel estimation accuracy for wideband XL-MIMO. To tackle this problem, this paper proposes a bilinear pattern detection (BPD)-based approach to accurately recover the wideband XL-MIMO channel. Specifically, by analyzing the characteristics of near-field wideband channels, we first reveal the bilinear pattern of the near-field beam split effect, which implies that the sparse support set of near-field channels in both the angle and the distance domains can be regarded as a linear function against frequency. Then, inspired by the classical simultaneously orthogonal matching pursuit technique, we use the bilinear pattern to estimate the angle-of-arrival (AoA) and distance parameters of each near-field path component at all frequencies. In this way, the entire wideband XL-MIMO channel can be recovered by compressed sensing algorithms. Moreover, we provide the computational complexity of the proposed algorithm compared with existing algorithms. Finally, simulation results demonstrate that our scheme can achieve the accurate estimation of the near-field wideband XL-MIMO channel in the presence of near-field beam split effect.
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Acknowledgements
This work was supported in part by National Natural Science Foundation of China (Grant No. 62031019), National Key Research and Development Program of China (Grant No. 2020YFB1805005), and European Commission through the H2020-MSCA-ITN META WIRELESS Research Project (Grant No. 956256).
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Cui, M., Dai, L. Near-field wideband channel estimation for extremely large-scale MIMO. Sci. China Inf. Sci. 66, 172303 (2023). https://doi.org/10.1007/s11432-022-3654-y
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DOI: https://doi.org/10.1007/s11432-022-3654-y