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Advanced Antenna Techniques for IoT and 5G Applications

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A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Internet of Things".

Deadline for manuscript submissions: closed (25 August 2023) | Viewed by 38453

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Dr. Adrian Bekasiewicz

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Faculty of Electronics, Telecommunications and Informatics, Gdansk University of Technology, 80-233 Gdansk, Poland
Interests: surrogate-assisted design; circuit miniaturization; compact antennas; multi-objective optimization, computer-aided design; surrogate modeling; automated design of RF circuits and antenna structures
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Special Issue Information

Dear Colleagues,

Internet of Things (IoT) and fifth-generation mobile communication (5G) are the key technologies behind the development of sensor networks and connected devices. Seamless processing of diverse information—as the core concept of IoT—will eventually revolutionize nearly all aspects of our lives, including healthcare, logistics, navigation, and transport. On the other hand, 5G is perceived as a wireless backbone ensuring the high quality-of-service and reliability required to unleash the full potential of IoT-driven services. The development of IoT and 5G would not be possible without intricate wireless components. Connectivity solutions for IoT and 5G applications heavily rely on multiple-input multiple-output (MIMO) antennas, reconfigurable radiators, or advanced beamforming networks—all of which reach far beyond what is achievable by conventional antennas. However, industry-standard approaches are inefficient and prohibitively expensive when applied to their design. From this perspective, development of reliable and affordable antenna techniques for IoT and 5G applications is an important problem that remains unsolved.

Advanced antenna techniques for IoT and 5G applications encompass dedicated modeling methods, specialized design frameworks, approaches to automated integration of components, or performance validation algorithms. Furthermore, availability of suitable surrogate-assisted techniques is considered indispensable for reducing development cost of radiators, which is particularly important for applications that involve analysis of multi-physics phenomena or complex environments and their effects on system behavior.

The objective of this Special Issue is to report techniques for IoT and 5G antennas that reach beyond the frontiers of the current state of the art. The topics of interest cover design and modeling methods, beam control techniques, and optimization algorithms, including but not limited to:

Analysis of shadowing effects;
Algorithmic selection and generation of topologies;
Design and validation of beamforming networks;
Computer-aided design;
Energy harvesting;
Failure identification techniques;
Forward and inverse modeling techniques for 5G/IoT antennas and arrays;
MIMO structures and massive MIMO systems;
Miniaturization techniques;
Multi-physics modeling and optimization;
Radiation effects on living tissues;
Reconfigurable antennas;
Specialized optimization algorithms;
Structures and algorithms for automobile communication;
Surrogate-assisted methods;
Quality-of-service-oriented design
Telemedicine and biomedical applications;
Yield estimation and maximization techniques.

Dr. Adrian Bekasiewicz
Guest Editor

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Keywords

antenna arrays
automated antenna design
beamforming networks
computer-aided design
implantable antennas
massive MIMO
modeling methods
optimization algorithms
reconfigurable antennas
surrogate-assisted design

Published Papers (11 papers)

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14 pages, 551 KiB

Open AccessCommunication

A Novel Expectation-Maximization-Based Blind Receiver for Low-Complexity Uplink STLC-NOMA Systems

by Ki-Hun Lee and Bang Chul Jung

Sensors 2022, 22(20), 8054; https://doi.org/10.3390/s22208054 - 21 Oct 2022

Viewed by 1387

Abstract

In this paper, we revisit a two-user space-time line coded uplink non-orthogonal multiple access (STLC-NOMA) system for Internet-of-things (IoT) networks and propose a novel low-complexity STLC-NOMA system. The basic idea is that both IoT devices (stations: STAs) employ amplitude-shift keying (ASK) modulators and align their modulated symbols to in-phase and quadrature axes, respectively, before the STLC encoding. The phase distortion caused by wireless channels becomes compensated at the receiver side with the STLC, and thus each STA’s signals are still aligned on their axes at the access point (AP) in the proposed uplink STLC-NOMA system. Then, the AP can decode the signals transmitted from STAs via a single-user maximum-likelihood (ML) detector with low-complexity, while the conventional uplink STLC-NOMA system exploits a multi-user joint ML detector with relatively high-complexity. We mathematically analyze the exact BER performance of the proposed uplink STLC-NOMA system. Furthermore, we propose a novel expectation-maximization (EM)-based blind energy estimation (BEE) algorithm to jointly estimate both transmit power and effective channel gain of each STA without the help of pilot signals at the AP. Somewhat interestingly, the proposed BEE algorithm works well even in short-packet transmission scenarios. It is worth noting that the proposed uplink STLC-NOMA architecture outperforms the conventional STLC-NOMA technique in terms of bit-error-rate (BER), especially with high-order modulation schemes, even though it requires lower computation complexity than the conventional technique at the receiver. Full article

(This article belongs to the Special Issue Advanced Antenna Techniques for IoT and 5G Applications)

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21 pages, 5851 KiB

Open AccessArticle

Enhancing Handover for 5G mmWave Mobile Networks Using Jump Markov Linear System and Deep Reinforcement Learning

by Masoto Chiputa, Minglong Zhang, G. G. Md. Nawaz Ali, Peter Han Joo Chong, Hakilo Sabit, Arun Kumar and Hui Li

Sensors 2022, 22(3), 746; https://doi.org/10.3390/s22030746 - 19 Jan 2022

Cited by 5 | Viewed by 2266

Abstract

The Fifth Generation (5G) mobile networks use millimeter waves (mmWaves) to offer gigabit data rates. However, unlike microwaves, mmWave links are prone to user and topographic dynamics. They easily get blocked and end up forming irregular cell patterns for 5G. This in turn causes too early, too late, or wrong handoffs (HOs). To mitigate HO challenges, sustain connectivity, and avert unnecessary HO, we propose an HO scheme based on a jump Markov linear system (JMLS) and deep reinforcement learning (DRL). JMLS is widely known to account for abrupt changes in system dynamics. DRL likewise emerges as an artificial intelligence technique for learning highly dimensional and time-varying behaviors. We combine the two techniques to account for time-varying, abrupt, and irregular changes in mmWave link behavior by predicting likely deterioration patterns of target links. The prediction is optimized by meta training techniques that also reduce training sample size. Thus, the JMLS–DRL platform formulates intelligent and versatile HO policies for 5G. When compared to a signal and interference noise ratio (SINR) and DRL-based HO scheme, our HO scheme becomes more reliable in selecting reliable target links. In particular, our proposed scheme is able to reduce wasteful HO to less than 5% within 200 training episodes compared to the DRL-based HO scheme that needs more than 200 training episodes to get to less than 5%. It supports longer dew time between HOs and high sum rates by ably averting unnecessary HOs with almost half the HOs compared to a DRL-based HO scheme. Full article

(This article belongs to the Special Issue Advanced Antenna Techniques for IoT and 5G Applications)

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18 pages, 683 KiB

Open AccessArticle

Evaluation of 5G Positioning Performance Based on UTDoA, AoA and Base-Station Selective Exclusion

by Alda Xhafa, José A. del Peral-Rosado, José A. López-Salcedo and Gonzalo Seco-Granados

Sensors 2022, 22(1), 101; https://doi.org/10.3390/s22010101 - 24 Dec 2021

Cited by 18 | Viewed by 4626

Abstract

Accurate and reliable positioning solution is an important requirement for many applications, for instance, emergency services and vehicular-related use cases. Positioning using cellular signals has emerged as a promising solution in Global Navigation Satellite System (GNSS) challenging environments, such as deep urban canyons. However, harsh working conditions of urban scenarios, such as with dense multipath and Non-Line of Sight (NLoS), remain as one of the key factors causing the detriment of the positioning estimation accuracy. This paper demonstrates that the use of joint Uplink Time Difference of Arrival (UTDoA) and Angle of Arrival (AoA) gives a significant improvement in the position accuracy thanks to the use of antenna arrays. The new advances of this technology enable more accurate user locations by exploiting angular domains of propagation channel in combination with time measurements. Moreover, it is shown that a better localization is achieved by combining the joined UTDoA and AoA with a base-station selective exclusion method that is able to detect and eliminate measurements affected by NLoS. The proposed approach has been tested through simulations based on a deep urban deployment map, which comes with an experimental data file of the user’s position. A sounding reference signal of 5G new radio operating in the centimeter-wave band is used. The obtained results add value to the use of advance antennas in 5G positioning. In addition, they contribute towards the fulfillment of high-accuracy positioning requirements in challenging environments when using cellular networks. Full article

(This article belongs to the Special Issue Advanced Antenna Techniques for IoT and 5G Applications)

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14 pages, 2561 KiB

Open AccessArticle

Metamaterial-Inspired Flat Beamsteering Antenna for 5G Base Stations at 3.6 GHz

by João Ricardo Reis, Mário Vala, Tiago Emanuel Oliveira, Telmo Rui Fernandes and Rafael Ferreira Silva Caldeirinha

Sensors 2021, 21(23), 8116; https://doi.org/10.3390/s21238116 - 04 Dec 2021

Cited by 7 | Viewed by 2840

Abstract

In this paper, a metamaterial-inspired flat beamsteering antenna for 5G applications is presented. The antenna, designed to operate in the 3.6 GHz at 5G frequency bands, presents an unique flat form factor which allows easy deployment and low visual impact in 5G dense scenarios. The antenna presents a multi-layer structure where a metamaterial inspired transmitarray enables the two-dimensional (2D) beamsteering, and an array of microstrip patch antennas is used as RF source. The use of metamaterials in antenna beamsteering allows the reduction of costly and complex phase-shifter networks by using discrete capacitor diodes to control the transmission phase-shifting and subsequently, the direction of the steering. According to simulations, the proposed antenna presents steering range up to

\pm 20^{\circ}

, achievable in both elevation and azimuth planes, independently. To prove the concept, a prototype of the antenna has been built and experimentally characterised inside an anechoic chamber. Although constructed in a different substrate (FR4 substrate) as initially designed, beamsteering ranges up to

8^{\circ}

in azimuth and

13^{\circ}

in elevation, limited to the proposed case-studies, are reported with the prototype, validating the antenna and the usefulness of the proposed design. Full article

(This article belongs to the Special Issue Advanced Antenna Techniques for IoT and 5G Applications)

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17 pages, 28135 KiB

Open AccessArticle

A 28 GHz 2 × 2 Antenna Array with 10 Beams Using Passive SPDT Switch Beamforming Network

by Firas Abdul Ghani, Amir Mohsen Ahmadi Najafabadi, Heba Saleh, Murat Kaya Yapici and Ibrahim Tekin

Sensors 2021, 21(21), 7138; https://doi.org/10.3390/s21217138 - 27 Oct 2021

Cited by 1 | Viewed by 4950

Abstract

In this paper, a dual-polarized four-port 2 × 2 series fed antenna array operating at 28 GHz with beam-switching capability is proposed. The antenna array uses a simple passive beamforming network to switch the main beam. The presented antenna design is suitable for 5G user equipment and high data rates applications by which it has a compact size with low cost and complexity. The size of the antenna is 37.2 × 37.2 mm

^{2}

including the ground plane, and it produces 10 different switched beams by using only two simple 3 dB/90

^{\circ}

couplers which create the required amplitudes and phase excitations for the antenna elements. A one-port simple feeding mechanism including Peregrine PE42525 SPDT switch modules and a power divider is used to generate and measure the 10 switched beams. The antenna design is implemented on a two-layer 0.203 mm thick low-loss (

\tan δ

= 0.0027) Rogers 4003C substrate, and it has a measured 10 dB impedance bandwidth of 4 GHz (14.3%, from 26 GHz to 30 GHz) for all ports. Measured peak isolation between any dual-polarized ports of the antenna is better than 30 dB. The antenna has an average measured realized gain of 8.9 dBi and around 10 dB side lobe level (SLL) for all beams. The antenna has 3-dB coverage of 80

^{\circ}

to 90

^{\circ}

in 2D space and it has a maximum of ±26

^{\circ}

beam-steering angle. The antenna is designed and simulated using Ansys HFSS and fabricated using regular PCB processing. Full article

(This article belongs to the Special Issue Advanced Antenna Techniques for IoT and 5G Applications)

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14 pages, 3705 KiB

Open AccessArticle

A 28-GHz Switched-Beam Antenna with Integrated Butler Matrix and Switch for 5G Applications

by Sujae Lee, Yongho Lee and Hyunchol Shin

Sensors 2021, 21(15), 5128; https://doi.org/10.3390/s21155128 - 29 Jul 2021

Cited by 21 | Viewed by 3574

Abstract

This work presents a 28-GHz Butler matrix based switched-beam antenna for fifth-generation (5G) wireless applications. It integrates a 1 × 4 microstrip antenna, a 4 × 4 Butler matrix, and a single-pole four-throw (SP4T) absorptive switch in a single planar printed circuit board and is housed in a metal enclosure. Co-integration of a packaged switch chip with the Butler matrix based switched-beam antenna greatly enhances the form factor and integration level of the entire system. A wideband two-section branch line coupler is employed to minimize the phase and magnitude errors and variations of the Butler matrix. The aluminum metal enclosure stabilizes the electrical performances, reduces the sidelobes, and improves the structural stability. The fabricated antenna with the metal enclosure assembled has a dimension of 37 × 50 × 6.2 mm³. With an RF input signal fed to the antenna’s input port through a single Ka-band connector, and the switching states chosen by 2-bit dc control voltages, the antenna successfully demonstrates four directional switched beams. The beam switching operations are verified through the over-the-air far-field measurements. The measured results show that the four beam steering directions are −43°, −17°, +10°, +34° with side lobe levels < −5.3 dB at 28 GHz. The antenna also shows reasonably wideband radiation patterns over 27–29 GHz band. The 10-dB impedance bandwidth is 25.4–27.6 GHz, while a slightly relaxed 8-dB bandwidth is 25.2–29.6 GHz. Compared to previous works, this four-directional switched-beam antenna successfully exhibits the advantages of high integration level and satisfactory performances for the 28-GHz 5G wireless applications. Full article

(This article belongs to the Special Issue Advanced Antenna Techniques for IoT and 5G Applications)

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12 pages, 1577 KiB

Open AccessCommunication

Physical-Layer Security Improvement with Reconfigurable Intelligent Surfaces for 6G Wireless Communication Systems

by Janghyuk Youn, Woong Son and Bang Chul Jung

Sensors 2021, 21(4), 1439; https://doi.org/10.3390/s21041439 - 19 Feb 2021

Cited by 14 | Viewed by 3587

Abstract

Recently, reconfigurable intelligent surfaces (RISs) have received much interest from both academia and industry due to their flexibility and cost-effectiveness in adjusting the phase and amplitude of wireless signals with low-cost passive reflecting elements. In particular, many RIS-aided techniques have been proposed to improve both data rate and energy efficiency for 6G wireless communication systems. In this paper, we propose a novel RIS-based channel randomization (RCR) technique for improving physical-layer security (PLS) for a time-division duplex (TDD) downlink cellular wire-tap network which consists of a single base station (BS) with multiple antennas, multiple legitimate pieces of user equipment (UE), multiple eavesdroppers (EVEs), and multiple RISs. We assume that only a line-of-sight (LOS) channel exists among the BS, the RISs, and the UE due to propagation characteristics of tera-hertz (THz) spectrum bands that may be used in 6G wireless communication systems. In the proposed technique, each RIS first pseudo-randomly generates multiple reflection matrices and utilizes them for both pilot signal duration (PSD) in uplink and data transmission duration (DTD) in downlink. Then, the BS estimates wireless channels of UE with reflection matrices of all RISs and selects the UE that has the best secrecy rate for each reflection matrix generated. It is shown herein that the proposed technique outperforms the conventional techniques in terms of achievable secrecy rates. Full article

(This article belongs to the Special Issue Advanced Antenna Techniques for IoT and 5G Applications)

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23 pages, 6766 KiB

Open AccessArticle

Low-Cost Unattended Design of Miniaturized 4 × 4 Butler Matrices with Nonstandard Phase Differences

by Adrian Bekasiewicz and Slawomir Koziel

Sensors 2021, 21(3), 851; https://doi.org/10.3390/s21030851 - 27 Jan 2021

Cited by 3 | Viewed by 2289

Abstract

Design of Butler matrices dedicated to Internet of Things and 5th generation (5G) mobile systems—where small size and high performance are of primary concern—is a challenging task that often exceeds capabilities of conventional techniques. Lack of appropriate, unified design approaches is a serious bottleneck for the development of Butler structures for contemporary applications. In this work, a low-cost bottom-up procedure for rigorous and unattended design of miniaturized 4 × 4 Butler matrices is proposed. The presented approach exploits numerical algorithms (governed by a set of suitable objective functions) to control synthesis, implementation, optimization, and fine-tuning of the structure and its individual building blocks. The framework is demonstrated using two miniaturized matrices with nonstandard output-port phase differences. Numerical results indicate that the computational cost of the design process using the presented framework is over 80% lower compared to the conventional approach. The footprints of optimized matrices are only 696 and 767 mm², respectively. Small size and operation frequency of around 2.6 GHz make the circuits of potential use for mobile devices dedicated to work within a sub-6 GHz 5G spectrum. Both structures have been benchmarked against the state-of-the-art designs from the literature in terms of performance and size. Measurements of the fabricated Butler matrix prototype are also provided. Full article

(This article belongs to the Special Issue Advanced Antenna Techniques for IoT and 5G Applications)

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19 pages, 30574 KiB

Open AccessArticle

Design of mmWave Directional Antenna for Enhanced 5G Broadcasting Coverage

by Tao Hong, Shuli Zheng, Rongke Liu and Weiting Zhao

Sensors 2021, 21(3), 746; https://doi.org/10.3390/s21030746 - 22 Jan 2021

Cited by 12 | Viewed by 4188

Abstract

5G mmWave broadcasting is considered to be the main method of future broadcasting. However, the mmWave transmission has a large space loss, especially in tunnels. In order to compensate for the attenuation of the broadcast signal, a directional horn antenna is designed in this paper. Substrate integrated waveguide (SIW) technology, dual-element arrays and extension structures are used to improve the antenna structure and achieve good directional characteristics. The multi-objective genetic algorithm (MOGA) is used to optimize the antenna parameters and improve optimization efficiency. Ultimately, the whole antenna was 28.2 mm in length and 28.6 mm in width, and the FR4 material, with a relative permittivity of 4.4, was used as a dielectric plate. The maximum gain of the antenna is 8.06 dB, and the bandwidth with gain greater than 6.5 dB is nearly 2 GHz. Antenna performance simulation and test results show that the extended semicircular structure is beneficial in enhancing the directional radiation of the antenna. This provides a reference method for directional antennas applied to 5G millimeter wave bands to increase gain and narrow beams. Full article

(This article belongs to the Special Issue Advanced Antenna Techniques for IoT and 5G Applications)

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15 pages, 732 KiB

Open AccessLetter

Linear and Decoupled Decoders for Dual-Polarized Antenna-Based MIMO Systems

by Sara Shakil Qureshi, Sajid Ali and Syed Ali Hassan

Sensors 2020, 20(24), 7141; https://doi.org/10.3390/s20247141 - 13 Dec 2020

Cited by 1 | Viewed by 1778

Abstract

Quaternion orthogonal designs (QODs) have been used to design STBCs that provide improved performance in terms of various design parameters. In this paper, we show that all QODs obtained from generic iterative construction techniques based on the Adams-Lax-Phillips approach have linear and decoupled decoders which significantly reduce the computational complexity at the receiver. Our result is based on the quaternionic description of communication channels among dual-polarized antennas. Another contribution of this work is the linear and decoupled decoder for quasi-orthogonal codes for non-square as well as square designs. The proposed solution promises diversity gains with the quaternionic channel model and the decoding solution is independent of the number of receive dual-polarized antennas. A brief comparison is presented at the end to demonstrate the effectiveness of quaternion designs in two dual-polarized antennas over available STBCs for four single-polarized antennas. Linear and decoupled decoding of two quasi-orthogonal designs is shown, which has failed to exit previously. In addition, a QOD for

2 \times 1

dual-polarized antenna configuration using quaternionic channel model shows a 3 dB gain at

10^{- 5}

in comparison to the same code evaluated for

2 \times 2

complex representation of the quaternionic channel. This gain is further enhanced when the received diversity for these the cases is matched i.e.,

2 \times 2

. The code using the quaternionic channel model shows a further 13 dB improvement at

10^{- 5}

BER. Full article

(This article belongs to the Special Issue Advanced Antenna Techniques for IoT and 5G Applications)

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17 pages, 4796 KiB

Open AccessLetter

Ultrawideband, Wide Scanning Stripline-Fed Tightly Coupled Array Antenna Based on Parallel-Dipole Elements

by Xiuye Liang, Weishuang Yin, Ang Chen, Zhe Zhang, Jianping Zeng, Lei Shi, Fang Guan, Xiaohan Liu and Jian Zi

Sensors 2020, 20(18), 5065; https://doi.org/10.3390/s20185065 - 06 Sep 2020

Cited by 2 | Viewed by 4245

Abstract

A stripline-fed tightly coupled array antenna with compact size, large scan volume and low cross-polarization characteristics is proposed for ultrawideband (UWB) applications. Simple impedance-matching process is realized by using parallel dual dipoles. Meanwhile, the parallel symmetrical radiating structures minimize the cross-polarization field components [...] Read more.

^{\circ}

in the E-/D-planes (VSWR < 2.5) and H-plane (VSWR < 3.5). The cross-polarization levels remain below −29 dB at broadside. A 16 × 16 prototype is fabricated to demonstrate the design. The measured results are consistent well with the simulated ones. The overall size of the prototype at the lowest operating frequency is

3 \times 3 \times 0.4 λ_{0}^{3}

(

15 \times 15 \times 2 {cm}^{3}

). Due to its wide bandwidth, good electronic scan performance and compact size, the proposed antenna array is a good candidate for modern wireless platforms. Full article

(This article belongs to the Special Issue Advanced Antenna Techniques for IoT and 5G Applications)

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