Electronics

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13 pages, 5546 KiB

Open AccessArticle

Circular Polarization Annular Leaky-Wave Antenna with Conical and Broadside Beams

by Yuchen Ma, Haijiao Yang, Junhong Wang, Ying Zhu, Chong Pan and Xiang Wu

Electronics 2023, 12(13), 2761; https://doi.org/10.3390/electronics12132761 - 21 Jun 2023

Cited by 1 | Viewed by 993

In order to properly cover different scenarios, radiation patterns of antennas should be accordingly designed. However, most antennas are unable to provide either broadside beams or designable conical beams, which are the typically used radiation patterns for radio coverage, based on one single-structure [...] Read more.

In order to properly cover different scenarios, radiation patterns of antennas should be accordingly designed. However, most antennas are unable to provide either broadside beams or designable conical beams, which are the typically used radiation patterns for radio coverage, based on one single-structure format through adjusting parameters before fabrication. In this paper, a planar circular polarized (CP) annular leaky-wave antenna (LWA) is proposed, which is realized on an annular substrate-integrated waveguide (SIW). A broadside beam or a conical beam could be easily obtained through fabricating the LWA with different structural parameters. The operating frequency is 5.75 GHz. The LWA allows only the −1st spatial harmonic to radiate, while the fundamental wave and other spatial harmonics are suppressed in slow wave mode. In order to validate the design effectiveness, two examples for broadside beam and conical beam radiation are fabricated and measured. The measurement results show good agreement with the simulation results. The broadside beam LWA shows a gain of 9.75 dBic and the conical beam LWA with a beam angle of 13° has a gain of 7.93 dBic. The proposed LWA presents promising radiation performance and is a good candidate for wireless communication applications. Full article

(This article belongs to the Special Issue Massive MIMO Technology for 5G and Beyond)

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15 pages, 5299 KiB

Open AccessArticle

Experimental Validation and Applications of mm-Wave 8 × 8 Antenna-in-Package (AiP) Array Platform

by Yifa Li, Wei Fan, Huaqiang Gao and Fengchun Zhang

Electronics 2022, 11(23), 4055; https://doi.org/10.3390/electronics11234055 - 6 Dec 2022

Viewed by 1340

Abstract

Phased array antennas play an indispensable role in millimeter-wave (mmWave) communications. The Antenna-in-package (AiP) system combines advanced antenna and packaging technology, making it highly valuable for various cellular, radar and automative applications. The benefits it brings in terms of small size, low development [...] Read more.

Phased array antennas play an indispensable role in millimeter-wave (mmWave) communications. The Antenna-in-package (AiP) system combines advanced antenna and packaging technology, making it highly valuable for various cellular, radar and automative applications. The benefits it brings in terms of small size, low development costs, low power consumption and fast beam-steering capability further drive the vast deployment of phased array antennas in mmWave systems. In this paper, an 8 × 8 AiP experimental platform is presented and its operating performance is measured and analyzed. Further, two application examples of the AiP are presented, namely, a platform for investigating the phased array calibration performance of different methods, and an AiP-based channel sounder for channel characterization. The performance of the channel sounder is verified by analysing the angle of arrival (AoA), angle of departure (AoD) and propagation delay of the measured dominant propagation components (DPCs). Full article

(This article belongs to the Special Issue Massive MIMO Technology for 5G and Beyond)

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18 pages, 415 KiB

Open AccessFeature PaperArticle

High-Precision Iterative Preconditioned Gauss–Seidel Detection Algorithm for Massive MIMO Systems

by Mushtaq Ahmad, Xiaofei Zhang, Imran A. Khoso, Xinlei Shi and Yang Qian

Electronics 2022, 11(22), 3806; https://doi.org/10.3390/electronics11223806 - 19 Nov 2022

Cited by 3 | Viewed by 1417

Abstract

Signal detection is a serious challenge for uplink massive multiple-input multiple-output (MIMO) systems. The traditional linear minimum-mean-squared error (MMSE) achieves good detection performance for such systems, but involves matrix inversion, which is computationally expensive due to a large number of antennas. Thus, several [...] Read more.

Signal detection is a serious challenge for uplink massive multiple-input multiple-output (MIMO) systems. The traditional linear minimum-mean-squared error (MMSE) achieves good detection performance for such systems, but involves matrix inversion, which is computationally expensive due to a large number of antennas. Thus, several iterative methods such as Gauss–Seidel (GS) have been studied to avoid the direct matrix inversion required in the MMSE. In this paper, we improve the GS iteration in order to enhance the detection performance of massive MIMO systems with a large loading factor. By exploiting the property of massive MIMO systems, we introduce a novel initialization strategy to render a quick start for the proposed algorithm. While maintaining the same accuracy of the designed detector, the computing load is further reduced by initialization approximation. In addition, an effective preconditioner is proposed that efficiently transforms the original GS iteration into a new one that has the same solution, but a faster convergence rate than that of the original GS. Numerical results show that the proposed algorithm is superior in terms of complexity and performance than state-of-the-art detectors. Moreover, it exhibits identical error performance to that of the linear MMSE with one-order-less complexity. Full article

(This article belongs to the Special Issue Massive MIMO Technology for 5G and Beyond)

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14 pages, 5061 KiB

Open AccessFeature PaperArticle

Propagation Channel Characterization for 6–14 GHz Bands Based on Large Array Measurement for Indoor Scenarios

by Qi Wang, Xuefeng Yin, Jingxiang Hong and Guangzheng Jing

Electronics 2022, 11(22), 3675; https://doi.org/10.3390/electronics11223675 - 10 Nov 2022

Cited by 1 | Viewed by 1304

Abstract

The demand for wideband data transmission in the “next-generation” mobile communication system is growing rapidly. As the frequency band around 10 GHz could be the option for 6th-generation (6G) wireless communication systems. In this paper, a recently conducted measurement campaign in the 6–14 [...] Read more.

The demand for wideband data transmission in the “next-generation” mobile communication system is growing rapidly. As the frequency band around 10 GHz could be the option for 6th-generation (6G) wireless communication systems. In this paper, a recently conducted measurement campaign in the 6–14 GHz radio wave propagation channel using a large antenna array with 1024 elements is introduced. In order to investigate the behavior of the wideband channel, we have analyzed the channel characteristics with respect to different carrier frequencies, bandwidths, the locations of antenna elements, and user locations, aiming at exploring the spatio-frequency variability of channels in the massive multiple-input multiple-output (MIMO) scenarios. Moreover, the sparsity of the channel in frequency and spatial domains is evaluated through the degree of freedom (DoF) analysis, and statistical models are established. Full article

(This article belongs to the Special Issue Massive MIMO Technology for 5G and Beyond)

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23 pages, 2251 KiB

Open AccessArticle

Performance of Cooperative Relay NOMA with Large Antenna Transmitters

by Samuel Tweneboah-Koduah, Emmanuel Ampoma Affum, Kwame Agyemang-Prempeh Agyekum, Sunday Adeola Ajagbe and Matthew O. Adigun

Electronics 2022, 11(21), 3482; https://doi.org/10.3390/electronics11213482 - 26 Oct 2022

Cited by 5 | Viewed by 2055

Abstract

The potential of the Non-Orthogonal Multiple Access (NOMA) approach for wireless communications in the fifth generation (5G) and beyond can not be underestimated. This is because users with favorable channel conditions can serve as relays to improve system performance by employing Successive Interference [...] Read more.

The potential of the Non-Orthogonal Multiple Access (NOMA) approach for wireless communications in the fifth generation (5G) and beyond can not be underestimated. This is because users with favorable channel conditions can serve as relays to improve system performance by employing Successive Interference Cancellation (SIC). Lately, the combination of NOMA and the cooperative relay has attracted the interest of researchers. The analysis of cooperative relay NOMA (CR-NOMA) with a massive multiple-input multiple-output (mMIMO) system is mainly based on theoretical channel models such as the correlated-based stochastic channel model (CBSM) even though the geometric-based stochastic channel model (GBSM) has been found to provide better, practical and realistic channel properties. This, in our view, is due to computational challenges. Again, the performance of CR-NOMA systems using the GBSM channel model with large antenna transmitters and network coding schemes has attracted little attention in academia. Therefore, the need to study mMIMO CR-NOMA that considers channel properties such as path-loss, delay profile and tilt angle has become vital. Furthermore, the co-existing of large antenna transmitters with coding schemes needs further investigation. In this paper, we study the performance of a two-stage mMIMO CR-NOMA network where the transmitter is represented as a uniform rectangular array (URA) or cylindrical array (CA). The communication channel from the transmitter (TX) to the user equipment (UE) through a relay station (RS) is modeled with a 3GPP’s three-dimensional (3D) GBSM mMIMO channel model. To improve the analytical tractability of 3D GBSM, we defined the antenna element location vectors using the physical dimension of the antenna array and incorporated them into the 3D channel model. Bit-error rates, achievable rates and outage probabilities (OP) are examined using amplify-and-forward (AF) and decode-and-forward (DF) coding schemes. Results obtained show with fixed power allocation and SNR of 20 dB, far or weak users can attain a high achievable rate using DF and URA. Again, from the results, the combination of AF and CA presents better outage probabilities. Finally, the results indicate that the performance difference between CBSM and GBSM is marginal, even though the proposed 3D GBSM channel model has a higher degree of random parameters and computational complexities. Full article

(This article belongs to the Special Issue Massive MIMO Technology for 5G and Beyond)

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19 pages, 11135 KiB

Open AccessFeature PaperArticle

ELAA Channel Characterization with Parameter Estimation Based on a Generalized Array Manifold Model

by Guangzheng Jing, Jingxiang Hong, Xuefeng Yin, José Rodríguez-Piñeiro and Ziming Yu

Electronics 2022, 11(21), 3442; https://doi.org/10.3390/electronics11213442 - 25 Oct 2022

Viewed by 1232

Abstract

The extremely large antenna arrays (ELAAs) and millimeter-wave systems have become key techniques for obtaining higher frequency spectrum efficiency in sixth-generation (6G) communication systems. It is necessary to determine appropriate statistical models to describe the channel characteristics for the ELAAs, such as spatial [...] Read more.

The extremely large antenna arrays (ELAAs) and millimeter-wave systems have become key techniques for obtaining higher frequency spectrum efficiency in sixth-generation (6G) communication systems. It is necessary to determine appropriate statistical models to describe the channel characteristics for the ELAAs, such as spatial non-stationarity, dispersion in angular domain, and spatial consistency. Thus, a signal model based on the generalized array manifold (GAM) that describes the dispersion in direction using the definition of the slightly distributed scatterer (SDS) is proposed in this work. An estimator for the parameters of the GAM model, namely GAM Space-Alternating Generalized Expectation-maximization (GAM-SAGE), is also designed. Moreover, a method to obtain a stochastic SDS-based channel model (SBCM) that is capable of reproducing the spatial consistency is proposed. The method is then used to establish measurement-based models for line-of-sight (LoS) and non-line-of-sight (NLoS) scenarios using a

40 \times 40

receiver (Rx) planar antenna array at a carrier frequency of 40 GHz. The results demonstrate that the SBCM is capable of achieving spatially consistent results and outperforms the specular-path (SP) models in completely characterizing the ELAA channels at millimeter-wave bands, which are fundamental for the design of 6G. Full article

(This article belongs to the Special Issue Massive MIMO Technology for 5G and Beyond)

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10 pages, 2048 KiB

Open AccessArticle

Reconfigurable Intelligent Surface Physical Model in Channel Modeling

by Yiping Liu, Jianwu Dou, Yijun Cui, Yijian Chen, Jun Yang, Fan Qin and Yuxin Wang

Electronics 2022, 11(17), 2798; https://doi.org/10.3390/electronics11172798 - 5 Sep 2022

Cited by 1 | Viewed by 2095

Abstract

Reconfigurable intelligent surfaces (RISs) are one of the potential technologies for 6th generation (6G) mobile communication systems with superior electromagnetic (EM) wave-steering capability to effectively control the phase, amplitude, and polarization of the incident EM wave. An implementation-independent physical RIS model with key [...] Read more.

Reconfigurable intelligent surfaces (RISs) are one of the potential technologies for 6th generation (6G) mobile communication systems with superior electromagnetic (EM) wave-steering capability to effectively control the phase, amplitude, and polarization of the incident EM wave. An implementation-independent physical RIS model with key EM characteristics is especially crucial to RIS channel modeling considering the trade-off between complexity and accuracy. In this paper, a reflective RIS physical model is proposed to facilitate channel modeling in a system simulation. Based on the impinging EM wave of the last bounce to the RIS, the scattering field intensity of the target point is obtained using geometric optics and the electric field surface integration method of physical optics. The feasibility of the model is verified by a comparison of the simulation and test results. Full article

(This article belongs to the Special Issue Massive MIMO Technology for 5G and Beyond)

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21 pages, 3140 KiB

Open AccessArticle

A Theoretical Analysis of Favorable Propagation on Massive MIMO Channels with Generalized Angle Distributions

by Yuxiang Zhang, Jianhua Zhang, Jian Zhang, Guangyi Liu, Yuan Zhang and Yuan Yao

Electronics 2022, 11(14), 2150; https://doi.org/10.3390/electronics11142150 - 9 Jul 2022

Cited by 3 | Viewed by 1898

Abstract

Massive MIMO obtains the multiuser performance gain based on the favorable propagation (FP) assumption, defined as the mutual orthogonality of different users’ channel vectors. Until now, most of the theoretical analyses of FP are based on uniform angular distributions and only consider the [...] Read more.

Massive MIMO obtains the multiuser performance gain based on the favorable propagation (FP) assumption, defined as the mutual orthogonality of different users’ channel vectors. Until now, most of the theoretical analyses of FP are based on uniform angular distributions and only consider the horizontal dimension. However, the real propagation channel contains full dimensions, and the spatial angle varies with the environment. Thus, it remains unknown whether the FP condition holds in real deployment scenarios and how it impacts the massive MIMO system performance. In this paper, we analyze the FP condition theoretically based on a cluster-based three-dimensional (3D) MIMO channel with generalized angle distributions. Firstly, the FP condition’s unified mathematical expectation and variance expressions with full-dimensional angular integral are given. Since the closed-form expressions are hard to derive, we decompose generalized angle distributions, i.e., wrapped Gaussian (WG), Von Mises (VM), and truncated Laplacian (TL) into the functions of Bessel and Cosine basis by introducing Jacobi-Anger expansions and Fourier series. Thus the closed-form expressions of the FP condition are derived. Based on the above, we theoretically analyze the asymptotically FP condition under generalized angle distributions and then compare the impact of angular spreads on the FP performance. Furtherly, the FP condition is also investigated by numerical simulations and practical measurements. It is observed that environments with larger angle spreads and larger antenna spacing are more likely to realize FP. This paper provides valuable insights for the theoretical analysis of the practical application of massive MIMO systems. Full article

(This article belongs to the Special Issue Massive MIMO Technology for 5G and Beyond)

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