scholarly journals Reconfigurable Magneto-Electric Dipole Antennas for Base Stations in Modern Wireless Communication Systems

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Lei Ge ◽  
Xujun Yang ◽  
Zheng Dong ◽  
Dengguo Zhang ◽  
Xierong Zeng
Keyword(s):  
Wireless Communication ◽  
Communication Systems ◽  
Frequency Standard ◽  
Base Station ◽  
Base Stations ◽  
Wireless Communication Systems ◽  
Dipole Antennas ◽  
Base Station Antennas ◽  
Electric Dipole Antennas ◽  
Antenna Characteristics

Magneto-electric (ME) dipole antennas, with the function of changing the antenna characteristics, such as frequency, polarization, or radiation patterns, are reviewed in this paper. The reconfigurability is achieved by electrically altering the states of diodes or varactors to change the surface currents distributions or reflector size of the antenna. The purpose of the designs is to obtain agile antenna characteristics together with good directive radiation performances, such as low cross-polarization level, high front-to-back ratio, and stable gain. By reconfiguring the antenna capability to support more than one wireless frequency standard, switchable polarizations, or cover tunable areas, the reconfigurable ME dipole antennas are able to switch functionality as the mission changes. Therefore, it can help increase the communication efficiency and reduce the construction cost. This shows very attractive features in base station antennas of modern wireless communication applications.

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

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1439
Author(s):  
Janghyuk Youn ◽  
Woong Son ◽  
Bang Chul Jung
Keyword(s):  
Wireless Communication ◽  
Physical Layer Security ◽  
Communication Systems ◽  
Low Cost ◽  
Physical Layer ◽  
Base Station ◽  
Wireless Communication Systems ◽  
Secrecy Rate ◽  
Pilot Signal ◽  
Time Division

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.

scholarly journals Broadband Dual-Polarized 2 × 2 MIMO Antenna for a 5G Wireless Communication System

Electronics ◽  
2021 ◽  
Vol 10 (17) ◽  
pp. 2141
Author(s):  
Junghoon Cha ◽  
Choon-Seong Leem ◽  
Ikhwan Kim ◽  
Hakyoung Lee ◽  
Hojun Lee
Keyword(s):  
Wireless Communication ◽  
Communication Systems ◽  
Ground Plane ◽  
Wireless Communication Systems ◽  
Impedance Bandwidth ◽  
Dipole Antennas ◽  
Mimo Antenna ◽  
Coefficient Corrélation ◽  
Dual Polarized ◽  
5 Ghz

In this study, we proposed an indoor broadband dual-polarized 2 × 2 MIMO (multiple-input and multiple-output) antenna having dimensions of 240 mm × 200 mm × 40 mm, for application in 5G wireless communication systems. The proposed antenna comprised two vertically polarized circular monopole antennas (CMAs), two horizontally polarized modified rectangular dipole antennas (MRDAs), and a ground plane. The distance between the two MRDAs (MRDA1 and MRDA2) was 70.5 mm and 109.5 mm in the horizontal (x-direction) and 109.5 mm vertical (y-direction) directions, respectively. Conversely, the distance between the two CMAs (CMA1 and CMA2) was 109.5 mm and 70.5 mm in the horizontal (x-direction) and vertical (y-direction) directions, respectively. While the CMAs achieved broadband characteristics owing to the optimal gap between the dielectric and the driven radiator using a parasitic element, the MRDAs achieved broadband owing to the optimal distance between the dipole antennas. The observations in this experiment confirmed that the proposed could operate in the 5G NR n46 (5.15–5.925 GHz), n47 (5.855–5.925 GHz), n77 (3.3–4.2 GHz), n78 (3.3–3.8 GHz), and the n79 (4.4–5 GHz) bands. Moreover, it exhibited a wide impedance bandwidth (dB magnitude of ) of 101% in the 2.3–7 GHz frequency range, high isolation (dB magnitude of ), low envelope coefficient correlation (ECC), gain of over 5 dB, and average radiation efficiency of 87.19%, which verified its suitability for application in sub-6 GHz 5G wireless communication systems.

scholarly journals Predictive Wireless Channel Modeling of MmWave Bands Using Machine Learning

Electronics ◽  
2021 ◽  
Vol 10 (24) ◽  
pp. 3114
Author(s):  
Abdallah Mobark Aldosary ◽  
Saud Alhajaj Aldossari ◽  
Kwang-Cheng Chen ◽  
Ehab Mahmoud Mohamed ◽  
Ahmed Al-Saman
Keyword(s):  
Machine Learning ◽  
Deep Learning ◽  
Wireless Communication ◽  
Random Forests ◽  
Communication Systems ◽  
Channel Modeling ◽  
Base Station ◽  
Wireless Channel ◽  
Base Stations ◽  
Data Driven

The exploitation of higher millimeter wave (MmWave) is promising for wireless communication systems. The goals of machine learning (ML) and its subcategories of deep learning beyond 5G (B5G) is to learn from the data and make a prediction or a decision other than relying on the classical procedures to enhance the wireless design. The new wireless generation should be proactive and predictive to avoid the previous drawbacks in the existing wireless generations to meet the 5G target services pillars. One of the aspects of Ultra-Reliable Low Latency Communications (URLLC) is moving the data processing tasks to the cellular base stations. With the rapid usage of wireless communications devices, base stations are required to execute and make decisions to ensure communication reliability. In this paper, an efficient new methodology using ML is applied to assist base stations in predicting the frequency bands and the path loss based on a data-driven approach. The ML algorithms that are used and compared are Multilelayers Perceptrons (MLP) as a neural networks branch and Random Forests. Systems that consume different bands such as base stations in telecommunications with uplink and downlink transmissions and other internet of things (IoT) devices need an urgent response between devices to alter bands to maintain the requirements of the new radios (NR). Thus, ML techniques are needed to learn and assist a base station to fluctuate between different bands based on a data-driven system. Then, to testify the proposed idea, we compare the analysis with other deep learning methods. Furthermore, to validate the proposed models, we applied these techniques to different case studies to ensure the success of the proposed works. To enhance the accuracy of supervised data learning, we modified the random forests by combining an unsupervised algorithm to the learning process. Eventually, the superiority of ML towards wireless communication demonstrated great accuracy at 90.24%.

scholarly journals Cooperative beamforming for a double-IRS-assisted wireless communication system

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Guodong Tian ◽  
Rongfang Song
Keyword(s):  
Wireless Communication ◽  
Communication System ◽  
Communication Systems ◽  
Signal To Noise Ratio ◽  
Pso Algorithm ◽  
Base Station ◽  
Wireless Communication Systems ◽  
Wireless Communication System ◽  
Power Simulation ◽  
Reflecting Surface

AbstractIntelligent reflecting surface (IRS) has emerged as an innovative and disruptive solution to boost the spectral and energy efficiency and enlarge the coverage of wireless communication systems. However, the existing literature on IRS mainly concentrates on wireless communication systems assisted by single or multiple distributed IRSs, which are not always effective. In view of this issue, this paper considers a special double-IRS-assisted wireless communication system, where IRS1 and IRS2 are deployed near the base station (BS) and the user, respectively, and the transmitted signals reach the user via the cascaded BS-IRS1-IRS2-user channel only. We cooperatively optimize transmit and passive beamforming on the two IRSs based on the particle swarm optimization (PSO) algorithm to maximize the received signal power. Simulation indicates that despite no direct line-of-sight (LoS) path from the BS to the user, an excellent signal-to-noise ratio (SNR) is available at the receiver with the aid of two IRSs, which demonstrates that it is feasible to assist communication by double reflection links composed of two IRSs. Additionally, we unexpectedly find that when the positions of the two IRSs are fixed, by exchanging the positions of the BS and the user, the obtainable SNRs are similar.

scholarly journals Review of Recent Phased Arrays for Millimeter-Wave Wireless Communication

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3194 ◽  
Author(s):  
Aqeel Naqvi ◽  
Sungjoon Lim
Keyword(s):  
Wireless Communication ◽  
Millimeter Wave ◽  
Communication Systems ◽  
Phased Arrays ◽  
Path Loss ◽  
Directional Antennas ◽  
Base Stations ◽  
Wireless Communication Systems ◽  
Data Traffic ◽  
System Architectures

Owing to the rapid growth in wireless data traffic, millimeter-wave (mm-wave) communications have shown tremendous promise and are considered an attractive technique in fifth-generation (5G) wireless communication systems. However, to design robust communication systems, it is important to understand the channel dynamics with respect to space and time at these frequencies. Millimeter-wave signals are highly susceptible to blocking, and they have communication limitations owing to their poor signal attenuation compared with microwave signals. Therefore, by employing highly directional antennas, co-channel interference to or from other systems can be alleviated using line-of-sight (LOS) propagation. Because of the ability to shape, switch, or scan the propagating beam, phased arrays play an important role in advanced wireless communication systems. Beam-switching, beam-scanning, and multibeam arrays can be realized at mm-wave frequencies using analog or digital system architectures. This review article presents state-of-the-art phased arrays for mm-wave mobile terminals (MSs) and base stations (BSs), with an emphasis on beamforming arrays. We also discuss challenges and strategies used to address unfavorable path loss and blockage issues related to mm-wave applications, which sets future directions.

Sign in / Sign up

Export Citation Format

Share Document