Channel Estimation in Massive MIMO Systems for Spatially Correlated Channels with Pilot Contamination

Boulouird, Mohamed; Amadid, Jamal; Riadi, Abdelhamid; Hassani, Moha M’Rabet

doi:10.1007/978-981-16-3637-0_11

Cited by 12 publications

(9 citation statements)

References 20 publications

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“…In other words, to gain the full benefit of M‐MIMO technology, 2 the number of served users must be much smaller than the NoA located at each BS. Consequently, most studies assume that BSs are fitted with hundreds of antennas serving tens of users at the same time‐frequency band 8–13 . M‐MIMO technology typically operates under the time‐division duplex (TDD) protocol, which brings many features to the M‐MIMO network, such as the avoids of pilot overload 7,14 and channel reciprocity 15,16 .…”

Section: Introductionmentioning

confidence: 99%

An efficient hybrid strategy for uplink channel estimation in massive MIMO systems based on spatially correlated channels

Amadid

Zeroual

2023

Int J Communication

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Summary The channel estimation (CE) process is an important phase that has a considerable influence on the performance of massive multiple‐input multiple‐output systems, in particular, in a more realistic scenario where the channels are spatially correlated (ScD). Thereby, in this work, the uplink (UL) CE process and channel hardening (CH) feature is addressed for ScD Rayleigh fading channels using the statistical Bayesian minimum mean square error estimator. The spatial correlation (SC) of the channels is described using different models, namely, the Gaussian local scattering (GLS) model, the uniform local scattering model, and the proposed hybrid model. Each model (i.e., GLS model and the uniform local scattering model) is studied using two arrangements, that is, for a uniform linear array (ULA) and uniform planar array (UPA). Moreover, the CH feature is investigated under SC of the channels using different models. Furthermore, this study proposes an efficient hybrid strategy based on SC of the channels for UL CE; that is, this work proposes a hybrid covariance matrix (CM) for UPA arrangement by relying on the Kronecker product of the CMs generated through two ULA arrangements, where the first CM is generated through horizontal ULA using GLS model, whereas the second CM is generated through vertical ULA using uniform local scattering model (i.e., one‐ring model). Numerical results regarding CE and CH are provided to assert the theoretical expressions, where the CE is evaluated using the normalized mean square error, whereas the CH is assessed using the variance of CH.

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Section: Introductionmentioning

confidence: 99%

An efficient hybrid strategy for uplink channel estimation in massive MIMO systems based on spatially correlated channels

Amadid

Zeroual

2023

Int J Communication

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“…Furthermore, as the channels are generally spatially correlated in a real propagation environment, SC between channels is considered a more realistic phenomenon that describes the real-world situation. 4 Consequently, the literature provides several models that try to describe the SC between channels, namely the local scattering model, [5][6][7][8] the one-ring model, 7,[9][10][11] the exponential correlation (EC) model, [12][13][14] and others. 15(sect.7.4.2), 16,17 One of the most frequent models that describe the correlation between channels is the EC model, which generally relies on a single parameter that adjusts the correlation degree between the channels in a given array.…”

Section: Introductionmentioning

confidence: 99%

On channel estimation and spectral efficiency for cell‐free massive MIMO with multi‐antenna access points considering spatially correlated channels

Amadid

Belhabib

Khabba

et al. 2022

Trans Emerging Tel Tech

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Channel estimation (CE) and spectral efficiency (SE) are two processes that have a major influence on system performance, especially in a more practical channel scenario with spatially correlated Rayleigh fading. During this work, we address the uplink phase CE process and the SE for spatially correlated Rayleigh fading in a cell-free (CF) massive multiple-input multiple-output (M-MIMO) network and in the conventional M-MIMO network operating under the time-division duplex protocol. Since practical channels are correlated spatially with Rayleigh fading; thereby, this work addresses spatially correlated Rayleigh fading channels in both networks using a combination of the exponential correlation model with large-scale variation across the array. Moreover, this work addresses the correlated and uncorrelated channels, where the correlated one is investigated using two array arrangements, namely, a uniform linear array (ULA) and a uniform planar array (UPA). For the two networks, the CE and SE are addressed using the minimum mean square error (MMSE) estimator and the MMSE combining vector, respectively. We propose a novel array design for CF M-MIMO using the Kronecker product of a ULA arrangement, where each access point has a UPA arrangement. In other words, we propose the covariance matrix generated by the UPA arrangement for CF M-MIMO using the Kronecker product of the covariance matrix generated by the ULA arrangement for CF M-MIMO.Numerical results are presented to validate our theoretical expressions, where we evaluate the performance of the MMSE estimator and MMSE combining vector, respectively, using the normalized mean square error metric and the quantity of information effectively transmitted per second.

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“…However, there is a need to investigate the ZF precoding in FDD systems. The authors in Amadid et al (2022) and Boulouird et al (2022) consider the spatially correlated channel in TDD protocol. Therefore, there is an essential requirement to investigate the FDD massive-MIMO systems with limited CT considering different spatial correlation models.…”

Section: Introductionmentioning

confidence: 99%

Performance evaluation of frequency division duplex (FDD) massive multiple input multiple output (MIMO) under different correlation models

Abdul-Hadi

Naser

Alsabah

et al. 2022

PeerJ Computer Science

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Massive multiple-input multiple-output (massive-MIMO) is considered as the key technology to meet the huge demands of data rates in the future wireless communications networks. However, for massive-MIMO systems to realize their maximum potential gain, sufficiently accurate downlink (DL) channel state information (CSI) with low overhead to meet the short coherence time (CT) is required. Therefore, this article aims to overcome the technical challenge of DL CSI estimation in a frequency-division-duplex (FDD) massive-MIMO with short CT considering five different physical correlation models. To this end, the statistical structure of the massive-MIMO channel, which is captured by the physical correlation is exploited to find sufficiently accurate DL CSI estimation. Specifically, to reduce the DL CSI estimation overhead, the training sequence is designed based on the eigenvectors of the transmit correlation matrix. To this end, the achievable sum rate (ASR) maximization and the mean square error (MSE) of CSI estimation with short CT are investigated using the proposed training sequence design. Furthermore, this article examines the effect of channel hardening in an FDD massive-MIMO system. The results demonstrate that in high correlation scenarios, a large loss in channel hardening is obtained. The results reveal that increasing the correlation level reduces the MSE but does not increase the ASR. However, exploiting the spatial correction structure is still very essential for the FDD massive-MIMO systems under limited CT. This finding holds for all the physical correlation models considered.

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Channel Estimation in Massive MIMO Systems for Spatially Correlated Channels with Pilot Contamination

Cited by 12 publications

References 20 publications

An efficient hybrid strategy for uplink channel estimation in massive MIMO systems based on spatially correlated channels

An efficient hybrid strategy for uplink channel estimation in massive MIMO systems based on spatially correlated channels

On channel estimation and spectral efficiency for cell‐free massive MIMO with multi‐antenna access points considering spatially correlated channels

Performance evaluation of frequency division duplex (FDD) massive multiple input multiple output (MIMO) under different correlation models

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