Massive MIMO Applications Research Articles

Design of a 240 elements antenna system for 5G massive MIMO applications with an inclined beam and two operating modes

A massive MIMO (multiple-input-multiple-output) antenna system for 5G base stations is developed, featuring 240 elements and 60 ports. The system supports two modes: individual port operation and network operation. It has a rectangular shape with dimensions of 28×16.8×0.32 cm³ and consists of three layers per side, with 15 ports per layer. Each port contains a 2×2 patch sub-array operating at 3.5 GHz, with beam tilting to generate uncorrelated radiation patterns. The system provides a measured bandwidth of 252 MHz, covering the 3.39–3.64 GHz band. Gain and envelope correlation coefficients are evaluated according to mMIMO parameters. A prototype is fabricated, and the results obtained through CST simulations are validated by experimental measurements.

Analysis of Performance Improvement of Planar Antenna Arrays With Optimized Square Rings for Massive MIMO Applications

The power pattern of the conventional fully optimized planar arrays can be properly reshaped according to the required user-defined constraints. However, the practical implementation of such fully optimized large planar arrays is complex and expensive. This paper introduces a new and efficient technique that is capable of providing better performance and almost the same power pattern shapes as that of the conventional fully optimized planar arrays by optimally adjusting the element amplitude and phase excitations of the outer-square rings instead of all elements' excitations. The proposed technique starts with a massive fully planar array then divides it into two contiguous sub-planar arrays which are both symmetric about the original array center. The elements excitation amplitudes or phases of the outer sub-planar array are only adjusted to form the desired power pattern shapes, while the amplitudes or phases of the central sub-planar array elements which have usually higher weights than the outer elements are made constants (i.e., they made ones for the case of amplitude-only control and zeros for the phase-only control). The results demonstrate the capability of the proposed planar array to form the required power patterns with far less number of the adjustable elements.

Miniaturized Dual-polarized, High-gain, and Wideband Dielectric Resonator Antenna for Low Band Massive MIMO Applications

Miniaturized Dual-polarized, High-gain, and Wideband Dielectric Resonator Antenna for Low Band Massive MIMO Applications

A fully integrated wideband GaN Doherty power amplifier MMIC with high efficiency for 5G massive MIMO application

A fully integrated wideband GaN Doherty power amplifier MMIC with high efficiency for 5G massive MIMO application

Tunable high-gain graphene patch antenna for THz massive MIMO applications using FSS

Tunable high-gain graphene patch antenna for THz massive MIMO applications using FSS

Additively manufactured flexible on-package phased array antennas for 5G/mmWave wearable and conformal digital twin and massive MIMO applications

This paper thoroughly investigates material characterization, reliability evaluation, fabrication, and assembly processes of additively manufactured flexible packaging and reconfigurable on-package antenna arrays for next-generation 5G/mmWave wearable and conformal applications. The objective is to bridge the technology gap in current Flexible Hybrid Electronics (FHE) designs at mmWave frequencies and address the challenges of establishing future design standards for additively manufactured flexible packages and System-on-Package (SoP) integrated modules. Multiple 3D printed flexible materials have been characterized for their electrical and mechanical properties over the 5G/mmW frequency band (26–40 GHz), and the inkjet printed interconnects on 3D printed Polypropylene (PP) substrates demonstrated excellent electrical and mechanical performance during a 10,000-time cyclic bending test over typical wearable flexible radii down to 1 inch. A proof-of-concept flexible on-package phased array with an integrated microfluidic cooling channel on 3D printed substrates was fabricated and measured, demonstrating pm 37^{circ } beam steering capability with efficient cooling. The proposed reconfigurable design and low-temperature fabrication approach using additive manufacturing can be widely applied to next-generation highly-complex on-demand FHE, flexible multi-chip-module integration, and on-package phased-array modules for 5G/mmWave wearable and conformal smart skin, digital twin and massive MIMO applications.

Steerable Simultaneous Multibeam Antenna Based on Reconfigurable Reflectarray

Multi-beam system is a core part for wireless concurrent communication and massive MIMO applications. Traditional concurrent communication techniques, like phased-array or digital beam-forming (DBF) system, suffer from massive RF frontends or power-hungry high speed ADCs, which makes them complex and expensive in fabrication. Inheriting the advantages of reflectarray and passive multi-beam system, we reported in this letter a novel and cost-effective concept of steerable simultaneous multi-beam antenna (SMBA). New features and the practicality of it are fully verified with theoretical analysis and experimental implementation of a prototype working at 7GHz with 300MHz bandwidth. With multiple beams steered simultaneously, the SMBA can eliminate the crossover regions between adjacent beams of passive multi-beam antenna. Experimental results indicate its potential in the design of diverse concurrent communication systems such as base stations and point-to-point links.

Deepmimo: A Generic Deep Learning Dataset for Millimeter Wave and Massive Mimo Applications to Vehicular Communications

Deepmimo: A Generic Deep Learning Dataset for Millimeter Wave and Massive Mimo Applications to Vehicular Communications

Throughput, Spectral, and Energy Efficiency of 5G Massive MIMO Applications Using Different Linear Precoding Schemes

Throughput, Spectral, and Energy Efficiency of 5G Massive MIMO Applications Using Different Linear Precoding Schemes

Dynamic branch pruning aided low switching fixed complexity sphere decoding for small scale and massive MIMO detection

AbstractIn this article, we have proposed a dynamic branch pruning aided low switching fixed complexity sphere decoding (LSFSD) algorithm that can reduce the number of node visits in conventional fixed‐complexity sphere decoder (FSD) or imbalanced fixed‐complexity sphere decoder (IFSD) detector dynamically based on the channel condition. Further, we propose a low complexity QR‐based FSD ordering scheme in the real domain that requires half of the number of real arithmetic operations in the conventional case. As a case study, we have simulated the proposed algorithm for and MIMO system with 64‐QAM modulation. The simulation results show that the proposed algorithm can reduce approximately 50% of node visits to achieve a BER of . Additionally, a low complexity solution of the soft bit information generation method is also proposed. The concept is further extended to massive MIMO applications where the number of receiving antenna to transmit antenna ratio is close to one. A smaller node extension parameter is defined for the proposed detector to reduce the complexity in massive MIMO detection. Simulation results demonstrate that the proposed detection algorithm has significantly lower computational complexity than other recent state‐of‐the‐art detection algorithms for massive MIMO and large MIMO systems.

The Effect of Parasitic Patches Addition on Bandwidth Enhancement and Mutual Coupling in 2 × 2 Sub-Arrays

This paper presents a 2x2 sub-array design with elements having parasitic patches (PPs) for massive MIMO applications. We show that with greater number PPs, bandwidth can be increased considerably with respect to previous designs. The increase in element dimension and, consequentially, element spacings reduces the mutual coupling in the sub-array. The frequency chosen for the design is 3.5 GHz, one of the 5G frequency allocations. For each sub-array element, multiple PPs are placed on the top layer, aimed to enhance the bandwidth. A coaxial feeding probe is employed. Two types of single element antenna with 5 and 10 PPs exhibit a bandwidth of more than 600 MHz and 700 MHz or a fractional bandwidth of about 17% and 20%, respectively. Simulation results and measurements of the 2x2 sub-arrays with 5 PPs and 10 PPs elements show that the antennas meet the desired performance because the return loss is less than -10 dB in a bandwidth of 567 MHz and 730 MHz, respectively. Mutual coupling effects can be suppressed down to less than -20 dB in the frequency range of 3.202 GHz -3.934 GHz.

Reduced Complexity Precoding for One-Bit Signaling

A number of precoding methods have recently been proposed for massive MIMO scenarios that assume the use of one-bit digital-to-analog converters, or that constrain the signal to be of constant modulus. The methods that provide the best performance employ non-linear precoding techniques that require a search for a parameter vector of the same dimension as the number of antennas, which is prohibitively expensive for massive MIMO applications. In this paper, we propose a reduced complexity precoding method based on linear programming and constructive interference that exploits an initial approximate solution to significantly reduce the dimension of the search. In particular, the method uses the output of an initial quantized linear precoder and updates only those elements that do not satisfy a certain reliability condition. Simulations show that the resulting loss in performance due to the use of the simplified approach is insignificant provided that the reduced dimension is chosen to be large enough, but still much smaller than the number of antennas.

Error Analysis of Grouped Multilevel Space-Time Trellis Coding with the Combined Application of Massive MIMO and Cognitive Radio

In today’s scenario, demand for error-correcting codes with minimal error constraints for wireless communications. Multilevel coding scheme with trellis codes as component codes provides flexible data transmission rates, coding gain, diversity gain with improved spectral efficiency and low decoding complexity. This paper investigates the potential improvements by using the Multilevel coding scheme with massive Multiple-Input Multiple-Output in Cognitive Radio Networks with trellis codes as component codes. This paper discussed space-time coding with beamforming and antenna grouping according to the channel state information. Multilevel Space-time coding is based on multi-level Quadrature Amplitude Modulation signaling and beamforming to mitigate the effect of primary users for the enactment of secondary users in Cognitive Radio. The primary users provide channels dynamically to the secondary user for an unknown duration. Our transmission use Quadrature Amplitude Modulation based signals, with an adaptive grouping of antenna which weight according to the optimization, which inherently depends upon the resource allocation of the secondary user. The results show that the proposed coded system achieves Bit error rate/Symbol error rate/Frame error rate and Signal to noise ratio varies according to sources sensing time.

Estimation of Sparse Channel Using Bayesian Gaussian Mixture and CS-Aided Techniques for Pilot Contaminated Massive MIMO System

Massive MIMO is established by future wireless communication systems to facilitate real-time user applications with having a higher of data transfer rates and spectral efficacy through perfect channel knowledge. Many pilot reuse schemes are working to improve channel performance regarding pilot overhead and channel knowledge. However, the pilot contamination becomes a major challenging issue in massive MIMO applications due to erroneous channel state information between neighboring cells. To tackle this issue, analyzing to the estimation of channel parameters in the preferred paths and interference from neighboring cells in the underdetermined system is essential. For estimating the channel behavior over Sparse Bayesian and Compressed sensing Aided methods are proposed by surviving the Pilot contamination effects by changing the angular to beam domain for sparse channel approximation. Simulation results have demonstrated the effectiveness of Bayesian and compressed sensing by compared with the standard estimators in connection with estimation accuracy, especially in pilot contamination.

Fully connected feedforward neural networks based CSI feedback algorithm

In modern wireless communication systems, the accurate acquisition of channel state information (CSI) is critical to the performance of beamforming, non-orthogonal multiple access (NOMA), etc. However, with the application of massive MIMO in 5G, the number of antennas increases by hundreds or even thousands times, which leads to excessive feedback overhead and poses a huge challenge to the conventional channel state information feedback scheme. In this paper, by using deep learning technology, we develop a system framework for CSI feedback based on fully connected feedforward neural networks (FCFNN), named CF-FCFNN. Through learning the training set composed of CSI, CF-FCFNN is able to recover the original CSI from the compressed CSI more accurately compared with the existing method based on deep learning without increasing the algorithm complexity.

Millimeter-Wave Dual-Polarized Filtering Antenna for 5G Application

This article presents a novel dual-polarized millimeter-wave (mm-Wave) patch antenna with bandpass filtering response. The proposed antenna consists of a differential-fed cross-shaped driven patch and four stacked parasitic patches. The combination of the stacked patches and the driven patch can be equivalent to a bandstop filtering circuit for generating a radiation null at the upper band edge. Besides, four additional shorted patches are added beside the cross-shaped driven patch to introduce another radiation null at the lower band edge. Moreover, by embedding a cross-shaped strip between these four stacked patches, the third radiation null is generated to further suppress the upper stopband. As a result, a quasi-elliptic bandpass response is realized without requiring extra filtering circuit. For demonstration, a prototype was fabricated with standard PCB process and measured. The prototype operates in the 5G band (24.25-29.5 GHz) and it has an impedance bandwidth of 20%. The out-of-band gain drops over 15 dB at 23 and 32.5 GHz, respectively, which exhibits high selectivity. These merits make the proposed antenna a good element candidate for the 5G mm-Wave massive MIMO applications to reduce the requirements of the filters in the mm-Wave RF front ends.

A Decoupling Method for Antennas With Different Frequencies in 5G Massive MIMO Application

A method to weaken the interference of antennas working in different frequencies is proposed in this paper. It uses a Frequency Selective Surface (FSS) placed between two different antennas. For one antenna, the FSS acts as an electromagnetically transparent structure, so the electromagnetic wave will penetrate the FSS and radiates into the free space. For the other one, the FSS acts as an artificial magnetic conductor, reflecting the incoming energy. With this design, two adjacent antennas could keep their individual performance especially radiation patterns normal. It is worth noting that although the FSS has been used in many aspects, such as reducing antenna's radar cross section or reducing the coupling between the identical antennas, its application in the field of `different antennas decoupling' is the first time. An embodiment is displayed in this paper for verification. Two antennas worked at different bands of 5G are placed very close with an FSS structure inserted. It turns out that the whole antenna has good electrical and radiation properties over the working band. This decoupling strategy can be very useful in 5G Massive MIMO application.

QoS-Oriented joint optimization of resource allocation and concurrent scheduling in 5G millimeter-wave network

With the mature application of massive MIMO, challenges for massive backhaul data and ubiquitous user access in future mobile communication are effectively coped with the potential technology of millimeter wave integrated backhaul and access network (mm-wave IBAN). In order to fully exploit mm-wave directional transmission gain, how to improve the concurrent transmission performance of mm-wave IBAN through effective scheduling scheme under the consideration of resource allocation between the backhaul and access link is an intractable issue. In this paper, an enhanced reverse-TDD frame is designed for mm-wave IBAN, and the QoS-oriented joint optimization problem of resource allocation and concurrent scheduling between backhaul and access link is deeply investigated, where the number of the QoS-satisfied transmission flows is maximized. To obtain a pragmatic solution, a joint resource allocation and concurrent scheduling algorithm is proposed. In the proposed algorithm, the whole transmission duration in each scheduling period is divided into several stages and the transmission flows are partitioned into groups according to the designed QoS-aware priority, then bandwidth resources between backhaul and access in each stage are allocated. The transmission duration of each scheduled flow is determined finally. Performance evaluation of proposed algorithm is verified with extensive simulations in 60 GHz mm-wave IBAN under various system parameters. It is demonstrated that significant enhancements in terms of the network throughput and the number of the successful transmission flows are achieved in the proposed algorithm when compared with other state-of-the-art schemes.

Isolation improvement of UWB MIMO antenna utilising molecule fractal structure

A compact four-element UWB MIMO antenna is proposed and its characteristics are investigated. The proposed antenna has a hexagon molecule-shaped fractal structure as its radiating element. The antenna elements are placed orthogonally to each other in order to yield good isolation, without any additional decoupling structure. The band rejection in WLAN band is attained by etching a C-shaped slot on each radiating element. The antenna has a compact size of 40 × 40 × 1.6 mm 3 and exhibits stable omni-directional radiation pattern. In addition, it shows an acceptable impedance bandwidth ( S 11 <; -10 dB) in the range 2.4-10.6 GHz with an isolation better than -20 dB over the UWB range. The performance of the proposed antenna is calculated in terms of antenna characteristics and MIMO parameters. The isolation level in-between the elements is found to be reasonable for MIMO application. The simulated and measured results are in good accord which makes the antenna a suitable candidate for massive MIMO and high-density packaging applications.

Highly compact GaN-based all-digital transmitter chain including SPDT T/Rx switch for massive MIMO applications

AbstractThis paper presents a fully digital transmitter chain from baseband to antenna, including a modulator, two truly digital (i.e. fully switched) microwave power amplifiers and a transmit/receive switch. Both, amplifier and switch monolithic microwave integrated circuits were implemented in a GaN HEMT process. The novel amplifier design provides greatly reduced complexity, needing only three voltage sources. Measurements were conducted using 5, 20, and 100 MHz wide baseband signals. Carrier frequencies cover the 900 and 2000 MHz bands. For the 5 MHz BB signal an ACLR of over 52 dB is reached, fulfilling the 3GPP specs for base station use while still maintaining a final-stage drain efficiency of 46% at 6.5 dB peak to average power ratio. Full-scale output power at 30 V supply voltage was measured to exceed 3 W at 80% drain efficiency. Further features of this digital amplifier approach include small form factor and frequency agility, making it an ideal candidate for software defined radio.