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21 pages, 1452 KiB

Open AccessArticle

Spectral Efficiency of Precoded 5G-NR in Single and Multi-User Scenarios under Imperfect Channel Knowledge: A Comprehensive Guide for Implementation

by David Alejandro Urquiza Villalonga, Hatem OdetAlla, M. Julia Fernández-Getino García and Adam Flizikowski

Electronics 2022, 11(24), 4237; https://doi.org/10.3390/electronics11244237 - 19 Dec 2022

Cited by 5 | Viewed by 2214

Abstract

Digital precoding techniques have been widely applied in multiple-input multiple-output (MIMO) systems to enhance spectral efficiency (SE) which is crucial in 5G New Radio (NR). Therefore, the 3rd Generation Partnership Project (3GPP) has developed codebook-based MIMO precoding strategies to achieve a good trade-off [...] Read more.

Digital precoding techniques have been widely applied in multiple-input multiple-output (MIMO) systems to enhance spectral efficiency (SE) which is crucial in 5G New Radio (NR). Therefore, the 3rd Generation Partnership Project (3GPP) has developed codebook-based MIMO precoding strategies to achieve a good trade-off between performance, complexity, and signal overhead. This paper aims to evaluate the performance bounds in SE achieved by the 5G-NR precoding matrices in single-user (SU) and multi-user (MU) MIMO systems, namely Type I and Type II, respectively. The implementation of these codebooks is covered providing a comprehensive guide with a detailed analysis. The performance of the 5G-NR precoder is compared with theoretical precoding techniques such as singular value decomposition (SVD) and block-diagonalization to quantify the margin of improvement of the standardized methods. Several configurations of antenna arrays, number of antenna ports, and parallel data streams are considered for simulations. Moreover, the effect of channel estimation errors on the system performance is analyzed in both SU and MU-MIMO cases. For a realistic framework, the SE values are obtained for a practical deployment based on a clustered delay line (CDL) channel model. These results provide valuable insights for system designers about the implementation and performance of the 5G-NR precoding matrices. Full article

(This article belongs to the Special Issue Transmit and Receive Techniques for Next Generation Massive MIMO Systems)

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12 pages, 1304 KiB

Open AccessFeature PaperArticle

Performance Analysis Antenna Diversity Technique with Wavelet Transform Using Array Gain for Millimeter Wave Communication System

by Nagma Parveen, Khaizuran Abdullah, Md Rafiqul Islam and Muhammad Aashed Khan Abbasi

Electronics 2022, 11(16), 2626; https://doi.org/10.3390/electronics11162626 - 22 Aug 2022

Cited by 1 | Viewed by 1513

Abstract

Utilizing antenna diversity techniques has become a well-known approach to improve the performance of wireless communication systems. Multiple antenna arrays with half-length spacing, such as a uniform linear array (ULA), have been taken into consideration. Since 60 GHz is an unlicensed frequency band [...] Read more.

Utilizing antenna diversity techniques has become a well-known approach to improve the performance of wireless communication systems. Multiple antenna arrays with half-length spacing, such as a uniform linear array (ULA), have been taken into consideration. Since 60 GHz is an unlicensed frequency band and ideal for local propagation, it is where the technology is being used. The transmitter and receiver both accomplish QAM modulation and demodulation. The performance in terms of bit error rate (BER) was tested in MATLAB simulation software for all antenna diversity scenarios: the single input and single output (SISO) DWT, multiple input and single output (MISO) DWT, single input and multiple output (SIMO) DWT, and multiple input and multiple output (MIMO) DWT. The MIMO DWT was shown to be the best of them. The performance of MIMO OFDM using various wavelets was also simulated, and the performance of the Haar wavelet transform was 2 dB better than that of the other wavelet transform. Compared to simulation results, the analytical results showed good agreement with little discrepancy. Full article

(This article belongs to the Special Issue Transmit and Receive Techniques for Next Generation Massive MIMO Systems)

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12 pages, 6570 KiB

Open AccessArticle

Hybrid Precoding Based on a Switching Network in Millimeter Wave MIMO Systems

by Hongbin Yi, Xizhang Wei and Yanqun Tang

Electronics 2022, 11(16), 2541; https://doi.org/10.3390/electronics11162541 - 14 Aug 2022

Cited by 2 | Viewed by 1301

Abstract

Aiming at the algorithm difficult optimization of the fully-connected hybrid precoding structure and the complex hardware implementation in millimeter wave multiple-input multiple-output (MIMO) systems, this paper proposes a novel hybrid precoding structure based on a switching network (SNHBP). The structure enables the dynamic [...] Read more.

Aiming at the algorithm difficult optimization of the fully-connected hybrid precoding structure and the complex hardware implementation in millimeter wave multiple-input multiple-output (MIMO) systems, this paper proposes a novel hybrid precoding structure based on a switching network (SNHBP). The structure enables the dynamic grouping of the sub-arrays in three ways by switching the network, which can greatly reduce the hardware complexity, simplify the optimization algorithm, and avoid the performance degradation defect caused by a partially-connected structure. Through simulation of different antenna sizes and different numbers of RF chains, experimental results show that SNHBP can approach the performance of the full digital precoder. Under the condition of more than 2 RF chains, the difference between the unit structure and the full digital precoding is less than 0.13 dB. The spectral efficiency of the low-precision phase optimization algorithm is better than that of the partially-connected structure when the quantization bit of the phase shifter is 3. The feasibility of the three dynamic grouping schemes is verified, which is more beneficial to engineering implementation than the fully-connected structure. Full article

(This article belongs to the Special Issue Transmit and Receive Techniques for Next Generation Massive MIMO Systems)

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16 pages, 3675 KiB

Open AccessFeature PaperArticle

Bi-Objective Power Optimization of Radio Stripe Uplink Communications

by Filipe Conceição, Marco Gomes, Vitor Silva, Rui Dinis and Carlos Henggeler Antunes

Electronics 2022, 11(6), 876; https://doi.org/10.3390/electronics11060876 - 10 Mar 2022

Cited by 2 | Viewed by 1492

Abstract

The radio stripe (RS) system is a practical implementation of cell-free mMIMO, in which a set of multi-antenna access points (APs) serves at the same time-frequency resources the user equipment (UE) in the network. The APs are sequentially connected in a stripe, sharing [...] Read more.

The radio stripe (RS) system is a practical implementation of cell-free mMIMO, in which a set of multi-antenna access points (APs) serves at the same time-frequency resources the user equipment (UE) in the network. The APs are sequentially connected in a stripe, sharing the same fronthaul link to the central processing unit. This work considers an uplink power optimization problem that aims to enhance the network spectral efficiency (SE) by considering two metrics—the max–min fairness and the max–sum rate. We employ a meta-heuristic based on the differential evolution algorithm to solve the bi-objective optimization problem. The SE performances of the full power along with the single-objective and multiple-objective scenarios are analyzed and compared for the optimal sequential linear processing detection scheme. The bi-objective approach is able to unveil the trade-offs to identify solution balancing the SE distribution resulting from the optimization of the max–min fairness and the max–sum rate objective functions. Full article

(This article belongs to the Special Issue Transmit and Receive Techniques for Next Generation Massive MIMO Systems)

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26 pages, 20153 KiB

Open AccessArticle

Performance Analysis of Massive MIMO-OFDM System Incorporated with Various Transforms for Image Communication in 5G Systems

by Lavish Kansal, Salah Berra, Mohamed Mounir, Rajan Miglani, Rui Dinis and Khaled Rabie

Electronics 2022, 11(4), 621; https://doi.org/10.3390/electronics11040621 - 17 Feb 2022

Cited by 19 | Viewed by 4013

Abstract

Modern-day applications of fifth-generation (5G) and sixth-generation (6G) systems require fast, efficient, and robust transmission of multimedia information over wireless communication medium for both mobile and fixed users. The hybrid amalgamation of massive multiple input multiple output (mMIMO) and orthogonal frequency division multiplexing [...] Read more.

Modern-day applications of fifth-generation (5G) and sixth-generation (6G) systems require fast, efficient, and robust transmission of multimedia information over wireless communication medium for both mobile and fixed users. The hybrid amalgamation of massive multiple input multiple output (mMIMO) and orthogonal frequency division multiplexing (OFDM) proves to be an impressive methodology for fulfilling the needs of 5G and 6G users. In this paper, the performance of the hybrid combination of massive MIMO and OFDM schemes augmented with fast Fourier transform (FFT), fractional Fourier transform (FrFT) or discrete wavelet transform (DWT) is evaluated to study their potential for reliable image communication. The analysis is carried over the Rayleigh fading channels and M-ary phase-shift keying (M-PSK) modulation schemes. The parameters used in our analysis to assess the outcome of proposed versions of OFDM-mMIMO include signal-to-noise ratio (SNR) vs. peak signal-to-noise ratio (PSNR) and SNR vs. structural similarity index measure (SSIM) at the receiver. Our results indicate that massive MIMO systems incorporating FrFT and DWT can lead to higher PSNR and SSIM values for a given SNR and number of users, when compared with in contrast to FFT-based massive MIMO-OFDM systems under the same conditions. Full article

(This article belongs to the Special Issue Transmit and Receive Techniques for Next Generation Massive MIMO Systems)

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13 pages, 4209 KiB

Open AccessArticle

Printed Closely Spaced Antennas Loaded by Linear Stubs in a MIMO Style for Portable Wireless Electronic Devices

by Aqeel Ahmed Khan, Muhammad Saeed Khan, Syed Aftab Naqvi, Bilal Ijaz, Muhammad Asif, Esraa Mousa Ali, Salahuddin Khan, Ali Lalbakhsh, Mohammad Alibakhshikenari and Ernesto Limiti

Electronics 2021, 10(22), 2848; https://doi.org/10.3390/electronics10222848 - 19 Nov 2021

Cited by 7 | Viewed by 1651

Abstract

An easy-to-manufacture and efficient four-port-printed Multiple Input Multiple Output (MIMO) antenna operating across an ultra-wideband (UWB) region (2.9–13.6 GHz) is proposed and investigated here. The phenomenon of the polarization diversity is used to improve the isolation between MIMO antenna elements by deploying four [...] Read more.

An easy-to-manufacture and efficient four-port-printed Multiple Input Multiple Output (MIMO) antenna operating across an ultra-wideband (UWB) region (2.9–13.6 GHz) is proposed and investigated here. The phenomenon of the polarization diversity is used to improve the isolation between MIMO antenna elements by deploying four orthogonal antenna elements. The proposed printed antenna (40 × 40 × 1.524 mm³) is made compact by optimizing the circular-shaped radiating components via vertical stubs on top of the initial design to maximally reduce unwanted interaction while placing them together in proximity. The measurements of the prototype MIMO antennas corroborate the simulation performance. The findings are compared to the recent relevant works presented in the literature to show that the proposed antenna is suitable for UWB MIMO applications. The proposed printed UWB MIMO antenna could be a good fit for compact portable wireless electronic devices. Full article

(This article belongs to the Special Issue Transmit and Receive Techniques for Next Generation Massive MIMO Systems)

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19 pages, 2314 KiB

Open AccessArticle

Two-Step Multiuser Equalization for Hybrid mmWave Massive MIMO GFDM Systems

by Joumana Kassam, Manar Miri, Roberto Magueta, Daniel Castanheira, Pedro Pedrosa, Adão Silva, Rui Dinis and Atílio Gameiro

Electronics 2020, 9(8), 1220; https://doi.org/10.3390/electronics9081220 - 29 Jul 2020

Cited by 10 | Viewed by 2673

Abstract

Although millimeter-wave (mmWave) and massive multiple input multiple output (mMIMO) can be considered as promising technologies for future mobile communications (beyond 5G or 6G), some hardware limitations limit their applicability. The hybrid analog-digital architecture has been introduced as a possible solution to avoid [...] Read more.

Although millimeter-wave (mmWave) and massive multiple input multiple output (mMIMO) can be considered as promising technologies for future mobile communications (beyond 5G or 6G), some hardware limitations limit their applicability. The hybrid analog-digital architecture has been introduced as a possible solution to avoid such issues. In this paper, we propose a two-step hybrid multi-user (MU) equalizer combined with low complexity hybrid precoder for wideband mmWave mMIMO systems, as well as a semi-analytical approach to evaluate its performance. The new digital non-orthogonal multi carrier modulation scheme generalized frequency division multiplexing (GFDM) is considered owing to its efficient performance in terms of achieving higher spectral efficiency, better control of out-of-band (OOB) emissions, and lower peak to average power ratio (PAPR) when compared with the orthogonal frequency division multiplexing (OFDM) access technique. First, a low complexity analog precoder is applied on the transmitter side. Then, at the base station (BS), the analog coefficients of the hybrid equalizer are obtained by minimizing the mean square error (MSE) between the hybrid approach and the full digital counterpart. For the digital part, zero-forcing (ZF) is used to cancel the MU interference not mitigated by the analog part. The performance results show that the performance gap of the proposed hybrid scheme to the full digital counterpart reduces as the number of radio frequency (RF) chains increases. Moreover, the theoretical curves almost overlap with the simulated ones, which show that the semi-analytical approach is quite accurate. Full article

(This article belongs to the Special Issue Transmit and Receive Techniques for Next Generation Massive MIMO Systems)

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Review

Jump to: Research

18 pages, 1382 KiB

Open AccessFeature PaperReview

A Review on Cell-Free Massive MIMO Systems

by Joumana Kassam, Daniel Castanheira, Adão Silva, Rui Dinis and Atílio Gameiro

Electronics 2023, 12(4), 1001; https://doi.org/10.3390/electronics12041001 - 17 Feb 2023

Cited by 12 | Viewed by 5598

Abstract

Cell-free massive multiple-input multiple-output (CF mMIMO) can be considered as a potential physical layer technology for future wireless networks since it can benefit from all the advantages of distributed antenna systems (DASs) and network MIMOs, such as macro-diversity gain, high channel capacity, and [...] Read more.

Cell-free massive multiple-input multiple-output (CF mMIMO) can be considered as a potential physical layer technology for future wireless networks since it can benefit from all the advantages of distributed antenna systems (DASs) and network MIMOs, such as macro-diversity gain, high channel capacity, and link reliability. CF mMIMO systems offer remarkable spatial degrees of freedom and array gains to mitigate the inherent inter-cell interference (ICI) of cellular networks. In such networks, several distributed access points (APs) together with precoding/detection processing can serve many users while sharing the same time-frequency resources. Each AP can be equipped with single or multiple antennas, and hence, can provide a consistently adequate service to all users regardless of their locations in the network. This paper presents a detailed overview of the current state-of-the-art on CF systems. First, it performs a literature review of the conventional CF and scalable user-centric (UC) CF mMIMO systems in terms of the limited capacity of the fronthaul links and the connection between APs and user equipments (UEs). As beyond networks will rely on higher frequency bands, it is of paramount importance to discuss the impact of beamforming techniques that are being investigated. Finally, some of the CF promising enabling technologies are presented to emphasize the main applications in these networks. Full article

(This article belongs to the Special Issue Transmit and Receive Techniques for Next Generation Massive MIMO Systems)

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