Angle-Domain Aided UL/DL Channel Estimation for Wideband mmWave Massive MIMO Systems With Beam Squint

Jian, Mengnan; Gao, Feifei; Tian, Zhi; Jin, Shi; Ma, Shaodan

doi:10.1109/twc.2019.2915072

Cited by 56 publications

(35 citation statements)

References 32 publications

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“…Therefore, when we design massive MIMO systems, spatial-wideband effect should be taken into consideration, which leads to a reformulation of many fundamental issues of massive MIMO systems that use the extended conventional MIMO channel models. Authors in [26], [29]- [31] investigated channel estimation in massive MIMO systems via off-grid channel estimation methods and took beam squint effect into consideration. Full OFDM subcarriers were used for channel estimation in [26], [31] while comb-type pilots are utilized in [29], [30].…”

Section: B Related Workmentioning

confidence: 99%

Multipath Extraction Based UL/DL Channel Estimation for FDD Massive MIMO-OFDM Systems

Zhang

Qiu

2021

IEEE Access

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In this paper, we propose a multipath extraction based uplink/downlink channel estimation scheme for wideband massive multiple-input multiple-output (MIMO) systems, where orthogonal frequency division multiplexing (OFDM) is adopted and the beam squint effect is considered. Firstly, we investigate the spatial-and frequency-wideband effects and obtain the relationship between angle-delay information and coordinates of on-grid paths. Secondly, according to the spatial-and frequency-wideband effects, we design a pilot pattern in uplink training to ensure that exact paths can be acquired from limited potential paths. Combined with pilot pattern design, a modified density-based spatial clustering of applications with noise (M-DBSCAN) approach is proposed to acquire the on-grid potential paths. Potential paths are used for initialization in uplink channel extraction. Due to the fact that coordinates of only a few potential paths are close to those of true paths, the uplink multipath extraction problem can be regarded as an off-grid sparse signal reconstruction problem. To deal with this issue, an off-grid sparsity adaptive matching pursuit (OSAMP) based compressive sensing method with low computational complexity is proposed. In OSAMP, angle-delay information as well as path gains of exact paths are accurately estimated, which are further used for accomplishing the uplink channel reconstruction. Angle-delay reciprocity between uplink and downlink channels is exploited, and downlink channel estimation is accomplished with the help of uplink multipath extraction. Downlink pilots are only used for downlink path gain estimation, therefore, the downlink training overhead will be significantly reduced. Simulation results are provided to demonstrate the effectiveness of our proposed low computational complexity channel estimation method.INDEX TERMS Massive MIMO, wideband, channel estimation, beam squint, low computational complexity, angle-delay reciprocity.

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Section: B Related Workmentioning

confidence: 99%

Multipath Extraction Based UL/DL Channel Estimation for FDD Massive MIMO-OFDM Systems

Zhang

Qiu

2021

IEEE Access

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“…By projecting all frequencies to the central frequency and constructing the common analog Transmit Precoding (TPC) matrix for all subcarriers, several hybrid TPC schemes were proposed in [32] to design the analog and digital TPC matrices and mitigate the beam squint effect. The channel estimation schemes were proposed to exploit the characteristics of mmWave channels affected by beam squint for estimating the wideband mmWave massive MIMO channels [33]- [35], where the beam squint effect is not mitigated. To sum up, the triple squint effects are seldom considered in state-of-the-art channel estimation and hybrid beamforming solutions [21]- [29], [31]- [35] and can dramatically degrade the data transmission performance of THz UM-MIMO-based aeronautical communications.…”

Section: Introductionmentioning

confidence: 99%

Terahertz Ultra-Massive MIMO-Based Aeronautical Communications in Space-Air-Ground Integrated Networks

Liao

Gao

Wang

et al. 2021

IEEE J. Select. Areas Commun.

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The emerging space-air-ground integrated network has attracted intensive research and necessitates reliable and efficient aeronautical communications. This paper investigates terahertz Ultra-Massive (UM)-MIMO-based aeronautical communications and proposes an effective channel estimation and tracking scheme, which can solve the performance degradation problem caused by the unique triple delay-beam-Doppler squint effects of aeronautical terahertz UM-MIMO channels. Specifically, based on the rough angle estimates acquired from navigation information, an initial aeronautical link is established, where the delay-beam squint at transceiver can be significantly mitigated by employing a Grouping True-Time Delay Unit (GTTDU) module (e.g., the designed Rotman lens-based GTTDU module). According to the proposed prior-aided iterative angle estimation algorithm, azimuth/elevation angles can be estimated, and these angles are adopted to achieve precise beam-alignment and refine GTTDU module for further eliminating delay-beam squint. Doppler shifts can be subsequently estimated using the proposed prior-aided iterative Doppler shift estimation algorithm. On this basis, path delays and channel gains can be estimated accurately, where the Doppler squint can be effectively attenuated via compensation process. For data transmission, a data-aided decision-directed based channel tracking algorithm is developed to track the beam-aligned effective channels. When the dataaided channel tracking is invalid, angles will be re-estimated at the pilot-aided channel tracking stage with an equivalent sparse digital array, where angle ambiguity can be resolved based on the previously estimated angles. The simulation results and the derived Cramér-Rao lower bounds verify the effectiveness of our solution.Index Terms-Terahertz communications, aeronautical communications, ultra-massive MIMO, channel estimation and tracking, space-air-ground integrated network.The codes and some other associated materials of this work may be available at https://gaozhen16.github.io.

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“…More specifically, compressedsensing (CS) techniques estimate the MIMO channel responses under the sparsity constraints of the ST domain, with the main drawback of a high sensitivity to antenna calibrations, e.g., irregular sampling of ST and phase errors/drift of radio frequency (RF) converters [8]. Off-grid methods have also been considered, using the implicit Dirichlet kernel structure in the angular domain [9] and continuous angle-delay parameters [10]. Moreover, in [9] the spatial-wideband effect is considered, i.e., the fact that the delay by which a transmitted signal reaches different receive antennas may span multiple data symbols.…”

Section: Introductionmentioning

confidence: 99%

Estimation of Wideband Dynamic mmWave and THz Channels for 5G Systems and Beyond

Brighente

Cerutti

Nicoli

et al. 2020

IEEE J. Select. Areas Commun.

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Millimeter wave (mmWave) wideband channels in a multiple-input multiple-output (MIMO) transmission are described by a sparse set of impulse responses in the angle-delay, or space-time (ST), domain. These characteristics will be even more prominent in the THz band used in future systems. We consider two approaches for channel estimation: compressedsensing (CS), exploiting the sparsity in the angular/delay domain, and low-rank (LR), exploiting the algebraic structure of channel matrix. Both approaches share several commonalities, and this paper provides for the first time i) a comparison of the two approaches, and ii) new versions of CS and LR methods that significantly improve performance in terms of mean squared error (MSE), computational complexity, and latency. We derive the asymptotic MSE bound for any estimator of the ST-MIMO multipath channels with invariant angles/delays and time-varying fading, with unknown angle/delay diversity order: the bound also accounts for the degradation introduced by sub-optimal separable channel models. We will show that in the considered scenarios both CS and LR approaches attain the bound. Our performance assessment over ideal and 3 rd generation partnership project (3GPP) channel models, suitable for the fifth-generation (5G) and beyond of cellular networks, shows the trade-off obtained by the methods over various metrics: i) CS methods are converging faster than the LR methods, both attaining the asymptotic MSE bound; ii) the CS methods depend on the array manifold, while LR methods are independent of the array calibration; iii) CS solutions are more complex than LR solutions.

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Angle-Domain Aided UL/DL Channel Estimation for Wideband mmWave Massive MIMO Systems With Beam Squint

Cited by 56 publications

References 32 publications

Multipath Extraction Based UL/DL Channel Estimation for FDD Massive MIMO-OFDM Systems

Multipath Extraction Based UL/DL Channel Estimation for FDD Massive MIMO-OFDM Systems

Terahertz Ultra-Massive MIMO-Based Aeronautical Communications in Space-Air-Ground Integrated Networks

Estimation of Wideband Dynamic mmWave and THz Channels for 5G Systems and Beyond

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