On the spectral efficiency of space-constrained massive MIMO with linear receivers

IEEE Wireless Commun. Lett.

Greenstein

et al. 2017

Self Cite

Abstract-Closed-form approximations of the expected perterminal signal-to-interference-plus-noise-ratio (SINR) and ergodic sum spectral efficiency of a multiuser multiple-input multiple-output system are presented. Our analysis assumes spatially correlated Ricean fading channels with maximum-ratio combining on the uplink. Unlike previous studies, our model accounts for the presence of unequal correlation matrices, unequal Rice factors, as well as unequal link gains to each terminal. The derived approximations lend themselves to useful insights, special cases and demonstrate the aggregate impact of line-of-sight (LoS) and unequal correlation matrices. Numerical results show that while unequal correlation matrices enhance the expected SINR and ergodic sum spectral efficiency, the presence of strong LoS has an opposite effect. Our approximations are general and remain insensitive to changes in the system dimensions, signalto-noise-ratios, LoS levels and unequal correlation levels.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Impact of Line-of-Sight and Unequal Spatial Correlation on Uplink MU-MIMO Systems

IEEE Wireless Commun. Lett.

Greenstein

et al. 2017

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“…Due to its extremely short wavelengths, mmWaves are unable to propagate over large distances, and are primarily envisaged to operate in small-cellular scenarios, where there is a considerably higher probability of a terminal experiencing LoS propagation. To this end, several investigations have examined the performance of massive MIMO with Ricean fading [10][11][12][13], including studies which consider variability in the Ricean K-factors across multiple terminals [9,14].…”

Section: Introductionmentioning

confidence: 99%

“…In addition to the specular components, we consider spatially correlated MPCs. Hence, unlike previous works (see e.g., [10][11][12]), we define a terminal specific M ×M spatial correlation matrix for terminal 1 as R 1 . For consistency, we delay further discussion on the possible models for R 1 to Section VI.…”

Section: Introductionmentioning

confidence: 99%

Revisiting MMSE Combining for Massive MIMO over Heterogeneous Propagation Channels

2018 IEEE International Conference on Communications (ICC)

Matthaiou

et al. 2018

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We consider a massive multiple-input multipleoutput system with minimum-mean-squared-error processing on the uplink. A novel analytical framework is proposed to approximate the instantaneous signal-to-interference-plus-noise-ratio (SINR) of an arbitrary user terminal, as well as, the system sum spectral efficiency. Unlike previous studies, our methodology considers spatially correlated Ricean fading, with unequal Ricean K-factors, spatial correlation matrices and link gains across all terminals. Under this fully heterogeneous setting, we demonstrate that the SINR of a terminal can be tightly approximated by a linear combination of non-central chi-squared random variables, where the scaling depends on the individual link gains, K-factors, and eigenvalues of the terminal specific correlation matrices. Our approximations remain tight across the considered spatial correlation models, K-factor models, average uplink signal-to-noiseratios and number of receive antennas. Leveraging the general form of the SINR and sum spectral efficiency, an analytical method to approximate their statistical moments is presented utilizing the moment generating function. The generality of the aforementioned analytical results is demonstrated via several special cases of practical relevance.

“…• We analyze the performance of MU-MIMO systems with SC ULAs under correlated Ricean fading channels. In doing so, we extend and generalize the SC channel models presented in [3][4][5][6][7][8][9] to cater for unequal correlation matrices and unequal Rice factors for each terminal. To the best of the authors' knowledge, such generality in the channel model has not previously been considered.…”

Section: Introductionmentioning

confidence: 99%

Uplink analysis of large MU-MIMO systems with space-constrained arrays in Ricean fading

2017 IEEE International Conference on Communications (ICC)

Matthaiou

et al. 2017

Self Cite

Abstract-Closed-form approximations to the expected perterminal signal-to-interference-plus-noise-ratio (SINR) and ergodic sum spectral efficiency of a large multiuser multipleinput multiple-output system are presented. Our analysis assumes correlated Ricean fading with maximum ratio combining on the uplink, where the base station (BS) is equipped with a uniform linear array (ULA) with physical size restrictions. Unlike previous studies, our model caters for the presence of unequal correlation matrices and unequal Rice factors for each terminal. As the number of BS antennas grows without bound, with a finite number of terminals, we derive the limiting expected perterminal SINR and ergodic sum spectral efficiency of the system. Our findings suggest that with restrictions on the size of the ULA, the expected SINR saturates with increasing operating signal-to-noise-ratio (SNR) and BS antennas. Whilst unequal correlation matrices result in higher performance, the presence of strong line-of-sight (LoS) has an opposite effect. Our analysis accommodates changes in system dimensions, SNR, LoS levels, spatial correlation levels and variations in fixed physical spacings of the BS array.