Modern Wireless Communication Research Articles

A mutation hill climber for thinning of concentric circular antenna arrays

ABSTRACT Thinned concentric circular antenna arrays (CCAAs) are crucial in modern wireless communication systems. CCAAs are widely used for efficient communication, directivity, and beamforming capabilities. Nevertheless, CCAAs encounter a challenge of radiation patterns characterised by high sidelobe levels (SLL). Designing thinned CCAAs to surmount this limitation for optimal performance can be complex and challenging. This paper employs a mutation hill climber (MHC) algorithm to optimise the CCAA structure. The goal is to attain an optimal design that balances the number of switched-on elements and reduces the maximum SLL. The performance and efficacy of the MHC are examined using two different cases of thinned CCAA design: two-ring and ten-ring configurations. Simulation results reveal the superiority of the MHC over the latest binary metaheuristic techniques in achieving the lowest maximum SLL and the number of switched-on elements. For the two-ring thinned CCAA, the MHC effectively switched off 50 antenna elements, reducing the maximum SLL by 24.92 dB. Meanwhile, for the ten-ring thinned CCAA, the MHC reduced the number of switched-on antenna elements from 440 to 184, reducing the maximum SLL by 34.09 dB.

Revolutionizing connectivity: Unleashing the power of 5G wireless networks enhanced by artificial intelligence for a smarter future

In the context of 5G wireless networks, this paper addresses a crucial concern—data loss in Analog-to-Digital Converters (ADCs) embedded within Multiple Input Multiple Output (MIMO) channels, a prevalent challenge in modern wireless communication systems. Despite the integration of ADCs in MIMO configurations to mitigate this issue, their implementation introduces significant complexities. In response to this, the paper introduces an innovative and efficient approach aimed at enhancing channel estimation in 5G MIMO systems. The proposed methodology relies on a heuristic-based optimization technique within a channel prediction framework. The framework uses feedback information collected through a Cascade Fusion Serial Network (CFSN) to analyze the receiver-side error ratio and estimate the channel coefficients of MIMO systems at the transmitter. An attention mechanism is incorporated into the model design through the use of a Convolutional Neural Networks - Gated Recurrent Units (CNN-GRU) and a Multi-Scaled Stacked Auto encoder. Parameters of Attention CNN-GRU, Stacked Auto encoder, and CFSN are refined using the Whale Optimization method. The optimization objective is to minimize key metrics, including Root Mean Squared Error (RMSE), Bit Error Rate (BER), and Mean Squared Error (MSE) associated with the estimated channel. Experimental evaluations underscore the efficacy of the proposed MIMO model in the context of 5G networks. The results demonstrate improved convergence rates, heightened prediction performance, and reduced computational costs compared to existing methods. This research contributes valuable insights into addressing data loss challenges specific to 5G MIMO systems, providing a pioneering solution that integrates heuristic optimization, advanced neural network architectures, and nature-inspired algorithms for parameter tuning.

Reconfigurable Metamaterial Antenna based an Electromagnetic Ground Plane Defects for Modern Wireless Communication Devices

In this paper, a design of a microstrip antenna based on metamaterial (MTM) and electromagnetic band gap (EBG) arrays. The patch is structured from 5×3 MTM array to enhance the antenna bandwidth gain product. The individual unit cell is structured as a split ring (SRR) with a T-resonator. The ground plane is defected with an EBG to suppress the surface waves diffraction from the substrate edges. The antenna is printed on a Roger substrate with permittivity of 10.2 and 1 mm thickness. It is found that the proposed antenna provides a frequency resonance around 2.45 GHz and 3.5 GHz with another band between 4.6 GHz to 5.6 GHz which are very suitable for Wi-Fi and 5G networks. Nevertheless, the antenna gain is found to vary from 3.5 dBi to less than 6 dBi. The antenna size is reduced enough to λ/5 of the guided wavelength to fit an area of 12 mm×20 mm. The proposed antenna performance is controlled with two PIN diodes for reconfiguration process. The antenna frequency resonance bands are found to be well controlled by stopping the current motion at the particular band. The antenna is fabricated and tested experimentally. Finally, the simulated results are compared to those obtained from measurements to provide an excellent agreement to each other with error of less than 3%.

A Wide Bandwidth Vivaldi Antenna Suitable for 5G/6G Communication Utilizing a CMOS 0.18 μm Process

This text proposes a Vivaldi structure array antenna, using a power divider structure. The composition includes an antenna array with four antennas, suitable for a wideband array structure antenna in the 100 GHz frequency band. The goal is to address the challenges faced by monolithic systems in modern wireless communications, particularly the issue of the inapplicability of antennas on silicon substrates. The Vivaldi antenna was chosen for its wide bandwidth, high efficiency, and stable radiation pattern. It combines the characteristics of a wide scanning angle and ultra-wide bandwidth. Through integration with CMOS technology, the developed antenna achieved a bandwidth of 85.47–102.40 GHz. The peak gain reached −4 dBi, corresponding to a bandwidth of 17.7%. And the antenna volume was only 1.2 mm × 1.2 mm, demonstrating its immense potential in high-frequency wireless applications.

ED-SS based Cognitive Radio (CR) over Various Fading Channels for Modern Wireless Communications

Cognitive Radio (CR) has already been proved to provide the better solution for the problem of spectrum insufficiency in which every wireless system occupies the limited bandwidth spectrum (LBS) allotting to the licensed users. Sometimes, this LBS is empty in a certain place at a certain time that is called as spectrum holes estimated by spectrum sensing (SS). The spectrum sensing is the main technique used in cognitive radio and various spectrum sensing techniques are available in the literature such as: energy detection (ED), matched filter detection (MFD) and cyclo-stationary feature detection (CFD). In the present work, energy detection-spectrum sensing (ED-SS) based cognitive radio system has been implemented which can analyze the energy of the spectrum. The various fading channels such as additive white gaussian noise (AWGN), Rayleigh, and Nakagami have been incorporated in the present work over which the performance of cognitive radio has been analyzed and compared using the ED-SS technique. The experimental results show thatt the detection of the presence of primary user signal using proposed ED-SS technique is easier with low computational complexities in Cognitive Radio (CR) networks. The present work also demonstrates when the performance of proposed ED-SS technique over aforesaid three fading channels are compared, Nakagami-m fading channels exhibits superior improvement in Pd compared to Rayleigh and AWGN fading channels

ORBITAL ANGULAR MOMENTUM-BASED SLOT ARRAY ANTENNA FOR MODERN APPLICATIONS

Millimeter waves are the most promising waves for different modern wireless communication networks. This is due to their ability to carry big data with enhanced channel capacity. However, mm-waves suffer from low propagation due to the effects of high attenuation factors with high frequencies. Therefore, in this work, a three-dimensional structural antenna design with a slot array is proposed to achieve high gain through a two-port feeding operation for orbital angular momentum applications of modern communication systems. Also, the improved bandwidth of the proposed antenna makes it an excellent candidate for fifth-generation (5G) communications systems. The antenna depends on two concentric structures with conductive circular cross-sectional area. The first structure is shaped as a three-dimensional cone with a cylindrical waveguide. The second structure is shaped as a circular disc with a circular aperture. The two parts of the proposed antenna are concentered to be fed with two discrete ports from the side with a 900phase difference. It is determined that the proposed antenna offers an exceptional gain to vary from 10dBi to 20dBi within the frequency band from 3GHz to 30GHz. It is realized that such enhancement after introducing a conductive circular reflector underneath the conductive cone. The antenna shows a matching impedance below -10dB over the entire frequency band of interest. The antenna radiation proprietors at 25GHz and 26GHz at the E-plane and H-plane are characterized. Finally, the antenna performance is validated using two software packages based on CST studio and HFSS algorithms.

Transparent ionic liquid antenna based on multi-modes using multiple feeding structures

With the rapid development of modern wireless communication technology, there is an increasing demand for the functionality of the communication system carried by a single platform. To improve the utilization of the antenna, a multimode liquid antenna is proposed in this paper. The antenna is fabricated using 3D printing technology and mainly consists of a cylindrical dielectric resonator, a coaxial feeding structure, and a slot-coupling feeding structure. By hollowing out the middle of a resin container and filling it with low-loss ionic liquid with stable dielectric properties, a liquid dielectric resonator antenna (DRA) is formed. The various resonant modes (slot mode, HEM11δ, TM11δ, TM21δ, and TM31δ modes) can be excited by introducing different feeding structures. The operating frequencies and radiation patterns can be modulated by mode switching. Simulated and measured results show that the antenna operates in the frequency bands of 2.25–2.76 GHz (20.4 %) and 4.82–5.73 GHz (17.3 %), and the maximum gain can be up to 10.3 dBi. The proposed antenna structure avoids the complex RF control circuit design, which has various applications including 5G/6G communications, transparent electronic devices, and Internet of Things.

Enhancing spectrum utilization and primary user detection in cognitive radio networks through greedy cooperative spectrum sensing

The utilization of the spectrum is optimized through which primary users of modern wireless communication technologies might obtain a higher chance of detection. The research aims to study how the NI-USRP hardware platform can be used to set up greedy cooperative spectrum sensing for cognitive radio networks. Research primarily deals with energy detection and eigenvalue-based detection approaches, both of which are highly recognized for their capacity to sense the spectrum without having prior knowledge of the primary user signals. In the hardware arrangement, there is one transmitter and two cognitive radio receivers. LABVIEW makes it simple to deploy and maximizes the detection probability across a large sample. Here, it was demonstrated that cooperative spectrum sensing is superior to non-cooperative spectrum sensing, which results in a reduction in the risk of errors occurring during detection. The research discovered that the OR combination rule has a higher detection probability than the AND rule at the same time. The research emphasizes the significance of expanding cooperative spectrum sensing to improve overall detection capabilities. SNRs that are more than 10 dB allow the energy detector to operate, and the eigenvalue detector continues to work when the SNR drops to –9 dB.

Communication spectrum prediction method based on convolutional gated recurrent unit network

In modern wireless communication systems, the scarcity of spectrum resources poses challenges to the performance and efficiency of the system. Spectrum prediction technology can help systems better plan and schedule resources to respond to the dynamic changes in spectrum. Dynamic change in the spectrum refers to the changes in the radio spectrum in a wireless communication system. It means that the available spectrum resources may change at different times and locations. In response to this current situation, this study first constructs a communication collaborative spectrum sensing model using channel aliasing dense connection networks. Then, combining convolutional neural network and gated cyclic unit network in deep learning technology, a communication spectrum prediction model is built. It aims to achieve accurate perception and prediction of spectrum resources through the aforementioned spectrum sensing and prediction models. The results confirm that the proposed perception model has inconsistent perception accuracy under different number of secondary users, with a maximum of 0.99. It is verified that the proposed spectrum prediction model achieves a high prediction accuracy of 0.95 within 208 s and its performance outperforms current similar models. The results are based on the model's deep learning analysis of massive historical communication data, in which the optimized shuffle dense net model plus convolutional gated recurrent unit model is the key to achieve fast and accurate prediction. On the contrary, the highest spectrum prediction accuracy of Recurrent Neural Network (RNN), Long Short-Term Memory (LSTM), and Convolutional Neural Networks-Long Short-Term Memory (ConvLSTM) models are 0.86, 0.90, and 0.85, respectively. And the model needs to run for a longer period of time, up to 324, for ConvLSTM to reach the prediction accuracy value of 0.95. In summary, the perception and prediction model built by this research has good performance, and its application in the field of wireless communication can assist staff in better monitoring spectral changes, thereby making more efficient use of spectral resources.

A compact circularly polarized dual port MIMO antenna with DGS and parasitic patch for modern wireless communication and IOT applications

Abstract The article proposes a broadband dual-port planar multiple-input-multiple-output (MIMO) antenna for the lower sub-6 GHz band (1.67 GHz to 3.15 GHz) applications. The simple structure of the MIMO antenna system consists of a semi-annular ring-shaped patch with a covering cap-like structure connected with two symmetrical L-shaped structures. A partial ground with a rectangular mesh-like structure at the center is designed and the same rectangular mesh has been added as the parasitic element with the driven patch to attain circular polarization and enhanced isolation. The miniaturized dimensions of the two-port MIMO antenna system are 0.28 λ 0 × 0.54 λ 0. The suggested two-port MIMO antenna offers a wider impedance bandwidth (IBW) of 61.41% around the versatile resonant frequency of 2.4 GHz. The proposed MIMO also depicts a minimum isolation of 26 dB with an edge-to-edge spacing of 0.19 λ 0. An axial ratio bandwidth of 280 MHz is attained between 2.36 GHz and 2.64 GHz. The proposed antenna shows good IBW with excellent isolation, along with good radiation and MIMO diversity characteristics to operate at 2.4 GHz with circular polarization. The designed MIMO antenna can be utilized for IoT and modern mobile wireless applications as the broad bandwidth covers various IoT communication protocol frequencies such as 1.8 GHz (NB-IoT) and 2.4 GHz (Wireless LAN).

Single/bidirectional pattern and beamwidth reconfigurable array antenna using reconfigurable reflecting surface

AbstractThis study describes an array antenna that allows for reconfiguration of the three significant antenna properties, that is, radiation pattern, half‐power beamwidth (HPBW), and single and bi‐directional beam. A reconfigurable reflecting surface (RRS) has been designed and incorporated with the array antenna on the top and bottom. The RRS works to reflect or pass the incident electromagnetic wave. It enables us to reconfigure from single to multibeam radiation in the ±z direction. It also provides two levels of HPBW, that is, 49.6° and 95°. Eventually, the same three sets of antennae have been stacked and rotated with a 60° angle to achieve the radiation pattern reconfiguration in the entire azimuth plane. It conforms to reconfigure all three antenna properties in six directions at an equal interval of 60° angle. The achieved maximum gain in a narrow beam is 9.56 dBi. The proposed reconfigurable antenna array can be used in modern wireless communication applications.

Design and analysis of frequency selective surface embedded broadband high gain miniaturized antenna

SummaryIncorporating the better impedance matching capability of planar curved radiating patch, a miniaturized broadband planar antenna has been designed, analyzed, and integrated with frequency selective surface (FSS) to accomplish higher gain for various short‐range and long‐range modern wireless communication applications. Physical and electrical volume of the presented antenna is 25 × 20 × 1.6 and 0.25 × 0.20 × 0.016, respectively. The proposed radiating patch is constructed from a conventional rectangular patch by transforming the upper side of the patch into a semi‐circular shape and the lower side of the patch into a staircase‐like shape. Measured outcomes of the designed antenna show a very large operating bandwidth of 19.8 GHz (3–22.8 GHz) with a fractional bandwidth (FBW) of 153.5% and bandwidth dimension ratio (BDR) of 3070. An equivalent circuit model (ECM) of the proposed antenna is developed using an advanced design system (ADS) circuit simulator. The frequency responses of the ECM are compared with the simulation done by CST Microwave Studio Suite software and measurement results, which show good agreement. An FSS structure with stop band from 2–28 GHz is positioned beneath the proposed antenna at optimal position (27 mm below the antenna) to enhance the gain up to 8.9 dBi. The presented antenna and FSS are fabricated on FR4 substrate and experimentally verified using standard microwave measurement setup.

Design of Inner Matching Three-Stage High-Power Doherty Power Amplifier Based on GaN HEMT Model.

This paper introduces the structure and characteristics of an internal-matching high-power Doherty power amplifier based on GaN HEMT devices with 0.25 μm process platforms from the Nanjing Electronic Devices Institute. Through parameter extraction and load-pull testing of the model transistor, an EE_HEMT model for the 1.2 mm gate-width GaN HEMT device was established. This model serves as the foundation for designing a high-power three-stage Doherty power amplifier. The amplifier achieved a saturated power gain exceeding 9 dB in continuous wave mode, with a saturated power output of 49.7 dBm. The drain efficiency was greater than 65% at 2.6 GHz. At 9 dB power back-off point, corresponding to an output power of 40.5 dBm, the drain efficiency remained above 55%. The performance of the amplifier remains consistent within the 2.55-2.62 GHz frequency range. The measured power, efficiency, and gain of the designed Doherty power amplifier align closely with the simulation results based on the EE_HEMT model, validating the accuracy of the established model. Furthermore, the in-band matching design reduces the size and weight of the amplifier. The amplifier maintains normal operation even after high and low-temperature testing, demonstrating its reliability. In conjunction with DPD (digital pre-distortion) for the modulated signal test, the amplifier exhibits extremely high linearity (ACLR < -50.93 dBc). This Doherty power amplifier holds potential applications in modern wireless communication scenarios.

On autoregressive and neural methods for massive-MIMO channel de-noising

In modern wireless communication systems, the Multiple-Input Multiple-Output (MIMO) technology allows to greatly increase power efficiency, the serving area, and the overall cell throughput through the use of the antenna array beamforming. Nevertheless, the MIMO systems require accurate channel state knowledge to apply correct precoding. In 5G Time Division Duplex (TDD) systems, the Channel State Information (CSI) is obtained via Sounding Reference Signals (SRS) transmitted by the User Equipment (UE). UEs have limited power capabilities and thus cannot achieve high Uplink (UL) Signal-to-Noise Ratio (SNR) on gNodeB (gNB) in large bandwidth. There are multiple techniques that can be applied to improve the accuracy of Channel Estimation (CE) in noisy conditions. In this paper, we describe a classical method, namely the Vector Autoregression (VAR) with adaptive model order estimation, as well as a modern Deep Neural Network (DNN) approach for the massive-MIMO channel estimation de-noising problem. The developed methods and signal pre and postprocessing steps are described, followed by their performance evaluation in a set of realistic simulations. The designed algorithms provide results outperforming the baseline spatio-temporal windowing approaches by approximately equal to 2dB effective Downlink (DL) Signal-to-Interference-plus-Noise Ratio (SINR) metric in single and multi-user MIMO scenarios. Extensive simulation results demonstrate the robustness of the developed methods to the dynamic channel conditions.

Frequency selective surface filters with high-quality factors based on a Fano resonance.

In this work, we propose a design method of the narrow passband filter with a high Q-factor based on a Fano resonance. A single-layer metallic frequency selective surface (FSS) with a simple structure is first designed according to this idea, but the result is not satisfying since the filter transmittance will significantly decrease with the increase of the Q-factor due to the presence of an inherent ohmic damping. Further, to improve the design, a ceramic-based FSS filter based on the similar mechanism is proposed, and the requirements of the ultrahigh Q-factors can be met owing to the high permittivity and low loss tangent of microwave ceramics. The design strategy proposed in this paper may have a promising potential in modern wireless communication and related fields.

Performance Analysis and Simulation of IRS-Aided Wireless Networks Communication

This paper introduces the novel IRS-based Optimal Relay Selection (ORS-IRS) method, aimed at analyzing the performance of wireless communication systems with an emphasis on symmetry. The ORS-IRS approach presents an innovative communication algorithm that seamlessly integrates Intelligent Reflecting Surfaces (IRS) with relay selection techniques. Through adaptive adjustments of reflection coefficients, IRS elements efficiently manipulate incoming signals, fostering symmetry in signal strength enhancement and latency reduction for improved signal delivery to the intended destination. This symmetrical optimization in channel capacity and transmission power ensures reliable data transmission with low latency, achieved through the seamless integration of IRS and relay selection techniques. In contrast, the Cell-Free Massive MIMO (CF-M-MIMO), with its decentralized architecture, excels in serving a larger user base and attaining remarkable capacity gains, showcasing a different dimension of symmetry. The Decode-and-Forward (DF) relaying approach demonstrates its potential in enhancing signal reliability across extended distances, contributing to the overall symmetry of the comparative analysis. This comprehensive evaluation provides valuable insights into selecting appropriate transmission strategies, particularly for applications that demand high capacity and reliability in the design of modern wireless communication systems with a symmetrical focus.

A Compact Bandpass Filter with Active Switchable Passband Status

In order to meet the increasing demand for adjustable devices in the modern wireless communication system, a compact bandpass filter with active switchable passband is proposed. The filter is based on the half mode substrate integrated waveguide (HMSIW), and uses its cut-off characteristics to form the lower stopband. The resonant characteristics of a quarter-wavelength shorted stub generates a transmission zero (TZ) at higher frequency, which forms the upper stopband. The active control of DC power supply determines the biased states of PIN diodes to change the electrical size of the filtering parts. When the diodes are reverse biased, the filter works in C band with the passband of 3.9-5.2 GHz; when the diodes are forward biased, the passband shifts to S band of 2.7-3.6 GHz. The 28.6% relative bandwidth in both frequency bands remains constant. The simple design realizes the active switching between bands, providing a promising idea for active adjustable devices.

Communication-Aware Control of Large Data Transmissions via Centralized Cognition and 5G Networks for Multi-Robot Map merging

Multiple modern robotic applications benefit from centralized cognition and processing schemes. However, modern equipped robotic platforms can output a large amount of data, which may exceed the capabilities of modern wireless communication systems if all data is transmitted without further consideration. This research presents a multi-agent, centralized, and real-time 3D point cloud map merging scheme for ceaselessly connected robotic agents. Centralized architectures enable mission awareness to all agents at all times, making tasks such as search and rescue more effective. The centralized component is placed on an edge server, ensuring low communication latency, while all agents access the server utilizing a fifth-generation (5G) network. In addition, the proposed solution introduces a communication-aware control function that regulates the transmissions of map instances to prevent the creation of significant data congestion and communication latencies as well as address conditions where the robotic agents traverse in limited to no coverage areas. The presented framework is agnostic of the used localization and mapping procedure, while it utilizes the full power of an edge server. Finally, the efficiency of the novel established framework is being experimentally validated based on multiple scenarios.

Applying Characteristic Impedance Compensation Cut-Outs to Full Radio Frequency Chains in Multi-Layer Printed Circuit Board Designs.

Modern wireless communication systems are of utmost importance to various sectors such as healthcare, education, the household, and the advancement of emerging technologies like the internet of things, autonomous vehicles, and the enhancement of 5G. Further development and improvement of these systems drives the need for small dimension, high integration and density, and cost-effective electronic devices. Achieving optimal performance in wireless electronic devices involves overcoming engineering challenges related to microstrip line signal integrity. This research addresses the impact of surface mount technology (SMT) component pads on signal integrity, proposing a novel high-frequency microstrip line structure for mitigating impedance discontinuities. The study introduces stepped microstrip lines and explores characteristic impedance compensation techniques. A six-layer printed circuit board (PCB) structure is presented, and the effects of compensation on signal integrity are analyzed using time-domain reflectometry and scattering parameter measurements. The results demonstrate the effectiveness of compensation methods in aligning characteristic impedance with desired values, thereby ensuring improved impedance matching and transmission coefficients. The average over-the-length impedance for the proposed structure with compensation applied was measured to be 52.7 Ω, which is only 1.3 Ω (2.5%) more than that of the reference microstrip. Applying reference plane cut-outs leads to a maximum compensated absolute value of more than 30 Ω to reach the target impedance with a 10% tolerance. This research contributes valuable insights for advancing wireless communication systems and maintaining robustness in high-frequency microstrip transmission lines.

A Dual-Band Dual-Polarized Antenna With High Aperture Reuse Efficiency and Large Frequency Ratio for Modern Wireless Communications

A Dual-Band Dual-Polarized Antenna With High Aperture Reuse Efficiency and Large Frequency Ratio for Modern Wireless Communications