Multi-input Multi-output Configuration Research Articles

A MIMO antenna array featuring dual wideband and high gain for 5G NR n257/n258/n260/n261 bands applications

This article introduces the development of a Multi-Input Multi-Output (MIMO) antenna array specifically designed for 5G millimeter-wave (mm-wave) communication systems. The suggested MIMO configuration consists of four antenna arrays, each comprising two elements arranged evenly, operating at 26 GHz and 37 GHz with a physical size of 43 mm × 32.5 mm × 0.8 mm using a Rogers RT/Duroid 5880 substrate. The proposed MIMO configuration provides dual bands, with frequency bands extending from 23.8 to 30 GHz (IBW = 6.2 GHz) and 32.5 to 41 GHz (IBW = 8.5 GHz), accompanied by high gains of around 18.5 dB for the first band and 16.4 dB for the second band. The designed antenna also shows broad circular polarization with 3 dB Axial Ratio Bandwidth (ARBW) of 4.75 GHz, ranging from 25.05 to 29.8 GHz. A physical prototype has been fabricated for the proposed 4 port MIMO antenna array and tested to verify the results acquired from simulations. The comparison between simulation and measurement results in terms impedance and radiation parameters such as S-parameters, isolation, gain, axial ratio (AR), efficiency, radiation patterns, and various necessary MIMO metrics demonstrates a strong alignment. This antenna covers various 5G New Radio (NR) application bands such as 28 GHz n257 (26.50–29.50 GHz), 26 GHz n258 (24.25–27.50 GHz), 28 GHz n260 (37–40 GHz) and 28 GHz n261 (27.50–28.35 GHz) utilized across different countries including Canada, Australia, China, France, Germany, India, Italy, Japan, South Korea, United Kingdom, and United States of America.

Four port MIMO antenna for IoT applications in public safety band and sub-6 GHz TDD 5G band

This paper proposes a Multi Input Multi Output (MIMO) antenna specifically developed for Internet of Things (IoT) Applications in Public Safety 4.9 GHz (4940–4990 MHz) band and Sub-6 GHz TDD 5G band (4800–4990 MHz). The proposed MIMO antenna consists of Koch fractal element, and it is introduced in four port configuration. HFSS is used to design, analyze, and optimize the performance parameters of the introduced MIMO antenna. To achieve optimum performance in terms of isolation, initially all two radiating elements of 1 × 2 MIMO configuration with varying orientations have been evaluated, which are positioned on top of a cost-effective FR4 substrate. Later on 2 × 2 and 1 × 4 MIMO configurations are evaluated; and 1 × 4 configuration is fabricated and tested in lab for the verification of simulated results. The MIMO antenna demonstrates resonance at 4.97 GHz, offering a bandwidth of 320 MHz (4795–5115 MHz). It exhibits excellent performance with Envelope Correlation Coefficient (EC-C) < 0.4, Diversity Gain (D-G) > 9.8, Mean Effective Gain (ME-G) < 3 dB, Total Active Refection Coefficient (TAR-C) < −14 dB, Channel Capacity Loss (CC-L) < 0.4 bits/s/Hz, and Isolation < −20 dB across the entire operating frequency range. The proposed MIMO antenna has a maximum gain of 1.2 dBi and radiation efficiency (η) of 80%. This proposed antenna offers several advantages over traditional ones, including high efficiency (η), low CC-L, and significant isolation, even without the use of special techniques to achieve isolation.

CSRR loaded multiband THz MIMO antenna for nano-communications and bio-sensing applications

In this paper, a multiband THz Multi-Input Multi-Output (MIMO) antenna is designed with dimensions of 80×100×10.8μm³. The antenna is made-up on a gold-plated Arlon AD410 substrate with a relative permittivity of 4.1.It operates at three resonant frequencies, namely 1.45THz, 2.25THz, and 3.25THz, achieved through the integration of Complementary Split-Ring Resonator (CSRR) and Substrate Integrated Waveguide (SIW) technologies. The two-element MIMO configuration of the antenna ensures exceptional performance, offering high throughput with data rates of 25.23Gbps for the Quadrature Phase Shift Keying (QPSK) scheme and 56.68Gbps for the 16-Quadrature Amplitude Modulation (QAM) scheme. It also exhibits remarkable channel capacity, approximately 8.2bps/Hz at Signal-to-Noise Ratio (SNR) = 20dB, surpassing the capabilities of single-element antennas. Moreover, it demonstrates excellent diversity performance for judging the MIMO antenna performance. This is evident through the following key metrics: Envelope Correlation Coefficient (ECC) < 0.02, indicating that less than 1 % of power is transferred from the excited antenna to the second 50Ω terminated antenna when antenna-1 is excited; Directive Gain (DG) >9.95dB; Total Active Reflection Coefficient (TARC) < -10dB, ensuring that a minimum of 90 % of the power is delivered to the patch port; and Channel Capacity Loss (CCL) < 0.35 bits/sec/Hz, guaranteeing reliable wireless communication. The antenna boasts peak gains of 3.83dBi, 4.06dBi, and 6.82dBi at 1.45THz, 2.25THz, and 3.25THz, respectively, along with a radiation efficiency of approximately 37, 58, and 51 % at the corresponding frequencies. Notably, the first two bands (1.34-1.51THz and 2.20-2.28THz) exhibit narrow bandwidths with quality factors above 80, making them particularly suitable for sensing applications in biomedical. Band-1 offers an average sensitivity of 3222.22 GHz/RIU and an FOM of 17.89, while Band-2 provides an average sensitivity of 2578.68 GHz/RIU and an FOM of 14.38. These characteristics make it well-suited for near-field Nano-communications and sensing applications.

Quad-Element MIMO Antenna System Using Half-Cut Miniaturized UWB Antenna for IoT-Based Smart Home Digital Entertainment Network

This work presents a miniaturized quad-element multi-input multi-output (MIMO) antenna with low mutual coupling, inherent isolation, and easy upgradability for an Internet of Things (IoT) based high-speed smart digital entertainment network using ultra-wideband (UWB) technology. Ultra Wideband (UWB) technology is anticipated to play a significant role in the future IoT based smart systems due to its ability to provide high precision location information, low power consumption, high data rates and secure communication. An elliptical quadrant-shaped radiator with a C-shaped protuberant ground plane is conceptualized as a quasi-monopole UWB antenna following the half-cut miniaturization approach with very compact dimensions of 18W11 mm2. The elliptical quadrant radiator in combination with C-shaped ground plane introduces multi-resonance characteristic in addition to providing better impedance matching with miniaturization and inherent high isolation for MIMO configuration. The single element antenna is then organized in an orthogonal arrangement with an edge-to-edge distance of 5 mm to develop a quad-element MIMO antenna system. The MIMO antenna structure realizes a wide bandwidth of 3.14-11.23 GHz (center frequency at 7.19 GHz), peak gain of 7.2 dBi, and radiation efficiency of above 60% with good isolation (>-20 dB) between the adjacent elements without employing any dedicated decoupling structure. The diversity performances of the proposed MIMO antenna are relatively good, with a very low envelope correlation coefficient (ECC) of less than 0.35 and diversity gain (DG) nearly at 10. Further, the total active reflection coefficient (TARC) <-10 dB and channel capacity loss (CCL) <0.4 bit/s/Hz, parameters are witnessed to be within acceptable limits. The simulated and measured results agree well, testifying that the proposed four-element MIMO antenna is suitable for UWB applications.

Multi-input multi-output antenna measurements with super wide bandwidth for wireless applications using isolated T stub and defected ground structure

The paper presents the idea of defective ground structures for the improvement in the radiation characteristics of the antenna especially in the multi-input multi-output (MIMO) configuration. The proposed antenna model with partially flared out feed system is designed and analyzed with defective ground in both single and array configuration. A T stub is a T shaped stub used in this work with defected ground structure. A T stub is included along with defective ground to enhance the MIMO configuration features. The simulations are carried out on electromagnetic modelling tool and analyzed by measuring the parameters like reflection coefficient, voltage standing wave ratio (VSWR), gain, radiation pattern and current distribution plots. For the fabrication of the proposed antenna these measurements are very important. The antenna is fabricated and validated in terms of S-parameters and VSWR. The proposed results are good agreement with the simulated results. The overall size of the antenna is 24 × 18 x 0.8 mm&lt;sup&gt;3&lt;/sup&gt;.

A novel dual band high gain 4-port millimeter wave MIMO antenna array for 28/37 GHz 5G applications

A new 4-port dual-band printed Multi-Input Multi-Output (MIMO) antenna array operating at 28 GHz and 38GHzin the mm-wave band for 5G communications is proposed in this paper. The designed MIMO antenna array consists of 4 MIMO elements structured with 8 identical patches arranged in 2 × 4 configuration and a cross-shaped defected ground plane on a physical footprint of 43.611×43.611×0.4mm3 Rogers RT/duroid 5880 substrate. In order to obtain the desired dual-band operation with good impedance matching, enhanced gain and bandwidth, the patch elements are designed by incorporating combinations of circular and semi-circular shaped slots, and the cross-shaped ground plane is modified with an extended circular-shaped defect. The suggested MIMO configuration offers a high gain of about 7.9 and 13.7 dB at 28 and 37.3 GHz, respectively. Furthermore, the MIMO performance metrics of the proposed design are analyzed and presented. The prototype of the designed MIMO antenna has been fabricated and measured to validate the simulation results. The simulation and measurement results show good agreement. The proposed MIMO antenna covers 28 GHz (27.50–28.35 GHz) and 37 GHz (37–37.6 GHz) 5G bands to be deployed in the USA and Canada.

Planar dual-band 27/39 GHz millimeter-wave MIMO antenna for 5G applications

This research work presents another design of a multi-input multi-output (MIMO) antenna with dual wide operating bands at the millimeter-wave (MMW) region proposed for 5G applications. The design consists of two monopole elements with full size of 26 × 11 mm2. The two monopoles are designed to provide dual-band operation at the frequencies 27 GHz and 39 GHz. The mutual coupling between the two elements is studied and optimized to maximally reduce the effect of one element on the other. The S-parameters of the proposed MMW MIMO configuration are simulated using two software and measured using VNA. The results are well agreed with considerable shifting between the measured and the simulated, which can be due to the fabrication tolerance and cable losses. The radiation characteristics are investigated in terms of gain and efficiency. The proposed MIMO manifests acceptable gain that reaches 5 dBi and 5.7 dBi in the first and second bands, respectively, while the radiation efficiency reaches 99.5% and 98.6% over the first and the second bands, respectively. The MIMO performance is also studied where a very low envelope correlation of about 10–4 is obtained and a diversity gain of about 10 dB over the two operating bands is also achieved. The comparison between simulation and measurement shows the possible potential of the proposed MIMO antenna that makes it feasible for MMW 5G applications.

Systems Thinking in Software Projects-an Artificial Neural Network Approach

The authors discuss why the current conceptual base of project management research and practice continues to attract criticism since it does not adequately address the complexity that leads to software-project failure. To do so, the study explores systems thinking and artificial neural networks to shed light on complexity in software-project behavior using nonlinear functional relationships between critical success factors and project success to utilize their connectedness as an approach in order to create project-outcome prediction models. The artificial neural networks were used to create two project-outcome prediction models: one for a binary classification task to discriminate failed from successful projects using a multi-input-single-output configuration and one for a multi-task binary classification to discriminate success from failure in multiple project-success dimensions using a multi-input multi-output configuration. The results yielded high-performance values for a binary classification task, performed to predict overall project success, and slightly lower performance values for the multi-task binary classification, which was also performed to predict success in project-success dimensions. It was found that the nonlinear behavior of critical success factors may be used to create prediction models, by embedding equifinality and connectedness constructs that prove to be useful to understand projects as complex, multi-loop, and nonlinear systems. Further research is needed to investigate the causality between critical success factors in order to explore the possible propagation of critical success factors within a project system network and its implications on project success.

MIMO-OFDM NB-PLC Designs in Underground Medium-Voltage Networks

In this paper, we investigate the application of multi-input multi-output (MIMO) orthogonal frequency-division multiplexing (OFDM) to narrowband powerline communications (NB-PLC) over medium-voltage (MV) underground (UG) networks. We study different MIMO transmission scenarios with different injection configurations utilizing both the cable conductor and sheath phases. Multiconductor transmission line theory is used to accurately characterize the UG MV NB-PLC channel transfer function and evaluate the spatial correlation between the different conductor phases. The achievable data rates are evaluated for all configurations at different line lengths after optimizing the transmit energy allocation across the different spatial information streams subject to a transmit power spectral density constraint. The achievable data rates for MIMO configurations are shown to be significantly higher (by up to three times higher) compared to single-input single-output OFDM transmission. Moreover, we investigate the effects of practical design constraints, such as cyclic prefix length and bit caps, on the achievable data rates. Finally, we show how to reduce the complexity of both the transmitter and receiver implementations while minimizing the data rate loss.

Single Ring Slot-Based Antennas for Metal-Rimmed 4G/5G Smartphones

In this paper, multiband antennas based on a single ring slot are proposed for 4G/5G smartphone applications. The basic structure of the antenna is consisted of a large metal ground and an unbroken metal rim, in which a single 2 mm-wide ring slots is realized between the metal ground and rim. Here, a reconfigurable 4G antenna (820–960 and 1710–2690 MHz) is initially devised by loading multiple grounded stubs and a simple dc controlling circuit with varactor diode into the upper section of the ring slot. To further cover the sub-6 GHz spectrum (3400–3600 MHz) for future 5G communications, a four-element multi-input multi-output (MIMO) slot antennas configuration is designed by utilizing the lower section of the ring slot. A prototype antenna was fabricated, and good agreement is shown between the measured and simulated results. Due to the advantages such as multiband operation, MIMO configuration for 5G communications, high isolation, and compact structure, the proposed antenna design is attractive for 4G/5G smartphones.

TARGET DETECTION IN LOW GRAZING ANGLE WITH OFDM MIMO RADAR

In low grazing angle scenario, target detection performance is seriously deteriorated due to multipath effect. This paper deals with moving target detection in low grazing angle with orthogonal frequency division multiplexing (OFDM) multi-input multi-output (MIMO) radar. We show that the detection performance can be improved through utilizing the multipath effect. Realistic physical and statistical effects such as refraction of the lower atmosphere and the Earth’s curvature are incorporated into the multipath propagation model. Then, we derive a generalized likelihood ratio test (GLRT) detector by taking advantage of the frequency diversity of OFDM and MIMO configuration. Based on the fact that the target responses resonate at different frequencies and statistical characteristics of the test, we propose an algorithm which adaptively allocates the transmitted energy to improve the detection performance. The effectiveness of the GLRT detector as well as the adaptive design method is demonstrated via numerical examples.

New rank detection methods for reduced-rank MIMO systems

In practical multi-input multi-output (MIMO) systems, the channel matrices often have reduced rank. Reliable detection of the channel rank is essential in achieving the significant gain provided by MIMO configuration. Existing work on MIMO channel rank detection assume a static channel model, so the proposed methods only consider the noise distributions while the distributions of the MIMO channels are not considered. In this paper, we employ a random channel model and propose three threshold-based rank detection methods which take into account the distributions of both the channels and the noises. In our first algorithm, following existing single-threshold rank detection scheme, we rigorously derive an analytical lower bound on the correct rank detection probability and propose a systematic threshold selection method by maximizing the lower bound. Then we propose two new rank detection methods which use multiple thresholds, where each threshold corresponds to one possible rank value. The thresholds are optimized based on the derived lower bounds on the rank detection probability for different channel rank values. The convergence and complexity of the proposed algorithms are analyzed. Simulation results on the correct rank detection probability of the proposed schemes are provided to show their advantage over existing schemes. The mean-squared-error (MSE) and outage probability are also simulated to show the importance of reliable rank detection in MIMO communications.

Temperature Control Using Hybrid Control with MRAC and ECS into a MIMO Microwave Heating Process

Microwave heating is an advanced heating technique in which heat is generated inside the material, but thermal runaway phenomenon is still the major challenge of the microwave heating process. The application of a hybrid temperature control structure with model reference adaptive control (MRAC) and expert control system (ECS) to a multi-input multi-output (MIMO) microwave heating process is addressed in this paper. Two input variables, microwave power and ambient temperature, are considered to be regulated and controlled as the output variables to track the desired temperature profiles. Simulation tests are carried out in MIMO configuration to validate that the hybrid controller with MRAC and ECS achieves better control performance than the sole MRAC strategy.

수중 통신 환경을 위한 MIMO-OFDM 시스템 설계

In this paper, we first analyze the differences of underwater acoustic (UWA) orthogonal frequency division multiplexing (OFDM) systems and conventional terrestrial OFDM system, and give a simple introduction of the backgrounds. By considering the real UWA channel environments, the measured channel data is used to generate the UWA channel model and calculate the relative parameters for underwater OFDM systems. Practical least square (LS) based channel estimation with linear interpolation are adopted to obtain the channel state information (CSI) at receiver side. As multi-input multi-output (MIMO) processing techniques, Alamouti code is implemented and evaluated to perform for space time block coding (STBC) and space frequency block coding (SFBC) for UWA OFDM systems with the MIMO configuration of , at the same time, maximum ratio combining (MRC) is performed for the purpose of comparison. The simulation results show that, with perfect channel estimation, SFBC failed to work duo to the serious frequency selectivity of UWA channel environments. When the practical channel estimation is applied, in the case of STBC, the proposed 4-column pilot pattern gives better performance about 7dB than SISO system.