Applications In Wireless Communication Systems Research Articles

Terahertz device utilizing a transmissive geometric metasurface.

Due to potential applications in next generation high-capacity wireless communication systems, generating and controlling vortex beams carrying orbital angular momentum (OAM) has received considerable attention. In this work, a scheme is proposed to generate two/four splitting vortex beams and focusing vortex beams with different topological charges under left circularly polarized and right circularly polarized terahertz waves under incidence. The meta-unit cell consists of a two-flying-fish-shaped patterned metallic top layer and an identical metallic patterned bottom layer separated by a silica layer. Full-wave simulation results agree well with that of calculation predictions. The proposed terahertz metasurface-based devices are able to carry different OAM modes and can abruptly manipulate during propagation, which indicates that such metasurface-based devices may have promising applications in terahertz wireless communication links in the future.

Double-layer geodesic and gradient-index lenses

A double-layer lens consists of a first gradient-index/geodesic profile in an upper waveguide, partially surrounded by a mirror that reflects the wave into a lower guide where there is a second profile. Here, we derive a new family of rotational-symmetric inhomogeneous index profiles and equivalent geodesic lens shapes by solving an inverse problem of pre-specified focal points. We find an equivalence where single-layer lenses have a different functionality as double-layer lenses with the same profiles. As an example, we propose, manufacture, and experimentally validate a practical implementation of a geodesic double-layer lens that is engineered for a low-profile antenna with a compact footprint in the millimeter wave band. Its unique double-layer configuration allows for two-dimensional beam scanning using the same footprint as an extension of the presented design. These lenses may find applications in future wireless communication systems and sensing instruments in microwave, sub-terahertz, and optical domains.

New Circular-Slot Circularly Polarized Antenna with Modified Characteristic

In this article, a novel broad circularly polarized antenna (CPA) with circular-slot ground is presented. The circular-slot CPA is consisted of a circular-slot ground, an I-shaped slit and a semicircle loop feeding structure. By using semicircle loop feeding structure and adding a slit into the circular-slot ground as perturbation elements, the multiple CP resonant modes could be stimulated simultaneously. To demonstrate to the design radiational, an antenna model was printed, manufactured, and tested. The tested results reveal that the proposed antenna has a broad 3-dB ARBW of |S11| < −10 dB that could be obtained, which is suitable for the application of wireless communication systems.

Coding‐Feeding Metasurface for Diffusion and Dual‐Band Emission

AbstractAs 2D metamaterials, metasurfaces are well known due to the distinctive manipulation of the amplitude, phase, polarization, and propagation for electromagnetic (EM) waves. However, the existing metasurfaces are mainly designed to control the incident waves. Herein, a coding‐feeding metasurface (CFMS) with two functions of dual‐band emission and diffusion for incidences simultaneously is proposed. The zigzag emission patch and two arc‐split triangle patches for polarization conversion are nested together on a shared aperture of a unit cell for CFMS. The genetic optimization algorithm is introduced for diffusion. A prototype is fabricated and measured to validate the proposed CFMS with dual‐function. The experimental results agree well with the simulated data, which verify the diffusion and emission for CFMS. The CFMS with the lightweight, compact, and low profile has the potential applications in imaging, detection, and wireless communication systems for stealth aircraft.

Digital Predistortion for Concurrent Dual-Band Millimeter Wave Analog Multibeam Transmitters

This brief proposes a novel digital predistortion (DPD) technique to linearize concurrent dual-band millimeter wave (mmWave) analog multibeam transmitters. Beams at the same frequency band give full play to the spatial multiplexing, so as to improve spectrum utilization. By means of detailed analysis of the system characteristics, a DPD model is proposed to effectively eliminate the distortions caused by power amplifiers (PAs) including nonlinearity, memory effect, the intermodulation distortion (IMD) between two different frequency bands, and the multibeam interference incurred in undesirable sidelobes in the main beam direction simultaneously. To validate the proposed idea, a test bench of mmWave analog multibeam transmitter utilizing Butler matrix was designed, and then it was stimulated by a concurrent dual-band signal at 26.91 GHz and 27.09 GHz, respectively. Compared with existing DPD techniques, the proposed method is suitable for compensating the distortions in dual-band analog multibeam transmitters, which has shown its great potential for the applications in future mmWave concurrent dual-band multibeam wireless communication systems.

Single-beam leaky-wave antenna with wide scanning angle and high scanning rate based on spoof surface plasmon polariton

We propose a single-beam leaky-wave antenna (LWA) with a wide-scanning angle and a high-scanning rate based on spoof surface plasmon polariton (SSPP) in this paper. The SSPP transmission line (TL) is etched with periodically arranged circular patches, which converts the slow-wave mode into the fast-wave region for radiation. The proposed LWA is designed, fabricated, and tested. The simulated results imply that the proposed LWA not only achieves a high radiation efficiency of about 81.4%, and a high scanning rate of 12.12, but also has a large scanning angle of 176° over a narrow operation bandwidth of 8.3–9.6 GHz (for |S 11| < –10 dB). In addition, the simulated average gain of the LWA can reach as high as 10.9 dBi. The measured scanning angle range is 175° in the operation band of 8.2–9.6 GHz, and the measured average gain is 10.6 dBi. The experimental results are consistent with the simulation, validating its performance. An antenna with high radiation efficiency, wide scanning angle range, and high scanning rate has great potential for application in radar and wireless communication systems.

Microstrip patch antenna design, simulation and fabrication for 5G applications

This study provides a deeper knowledge of the usage of finite integration techniques (FIT) and the finite element method (FEM) for analyzing various microstrip antenna shapes such as rectangular, circular and triangular patches. These patch shapes are fabricated practically and the efficiency of both mentioned methods have been identified through the evaluation of the microstrip antenna parameters such as, gain, bandwidth, VSWR, return loss S11, directivity and ration pattern operating at 28 GHz. Comparison between measured and simulated results with both techniques reveals that the FIT better for all types of microstrip antennas patch shapes whereas FEM is only reliable for rectangular microstrip antennas shape due to its regularity in its configuration. In addition, a good agreement between the results of the proposed antenna parameters with previously research works operating at the same frequency are also identified. Beside of this, our proposed antenna has the advantage of small size of the order of (5.2 mm3) which is compact and suitable for the 5 G wireless communication system applications. Furthermore, with this small profile configuration, the antennas still provide high radiation performance with a bandwidth of the order of (900 MHz), gain of (6 dB) and directivity of the order of (7 dB).

Non-Uniform Pitch Helical Resonators for Dual-Passband Filter Design

This paper presents a study of a non-uniform pitch helical resonator (NPHR) structure and the coupling mechanisms to design dual-passband filters. The previous research analyzes NPHR as a type of step impedance resonator (SIR), however, it does not give analytical equations or prediction for the dual-resonance characteristics of the NPHR structure discussed in this paper. Consequently, a circuit model is proposed to analyze the dual-resonance characteristics of NPHRs. Analytical equations are derived, showing that the frequency ratio of a dual-band NPHR can be determined by the ratio of turns. EM simulation and experimental results have shown good agreement with the circuit analysis. The derived analytical equations from circuit model can be used for fast design of NPHRs. A step-width aperture is proposed to independently control the coupling coefficients at the each band of NPHRs. A third order dual-passband filter has been designed and fabricated. The filter has 3.3% and 3% fractional bandwidths at 789 MHz and 2402 MHz, respectively. The designed prototype filter shows that NPHRs can be utilized to realize compact filters with dual-band characteristics. The filter design can be extended from engineering perspective for application in wireless communication systems.

High‐Precision Direction‐of‐Arrival Estimations Using Digital Programmable Metasurface

Commonly, phased array antennas are used to provide spatial resolution for direction of arrival (DOA) estimations. However, the phase‐array‐based DOA estimations usually require complicated system architecture and signal processing. Digital programmable metasurfaces (DPMs) can realize flexible spatial modulations of electromagnetic (EM) waves without using massive transceivers, and hence can be used for DOA estimations with much simplified architectures. Here, a mechanism of DPM‐based DOA estimations at Ka band is proposed. A reflective DPM is designed to produce a series of dual beams in random, so as to establish a sensing matrix and sample the incident wave. Orthogonal matched pursuit algorithm is used to estimate DOA from the sparsely sampled datasets. The performances of the DPM‐based DOA estimations are demonstrated by simulations and experiments for the cases of single source and double sources. This work promotes the development of DPMs and is expected to find important applications in radar and wireless communication systems, as well as the joint radar and communication systems.

New Design Approach of “3rd - Order Dipole Antenn” Based on Direct Coupled Resonator Bandpass Filter

ABSTRACT In ultra-wideband (UWB) antennas used with the applications of wireless communication systems (WCS), the following five antenna parameters; radiation patterns, directivity, bandwidth, efficiency and antenna gain should be well optimized. A new design approach-based on coupling matrix theory of synthesis antenna has been presented. The most important parameters of this matrix are; external normalized quality factor, normalized un-loaded quality factor, radiation quality factor and coupling coefficients between the resonators. Accuracy in calculating these parameters will greatly facilitate control of the antenna bandwidth to be designed. The design approach included a BPF which was also expanded to become an antenna arrays-filter in the hope of increasing the gain and bandwidth of the antenna. Further, a matching unit is placed between the designed BPF and the antenna, to overcome the mismatching situation, and to achieve a high transmission power. The paper presented a new design approach for an active BPF at frequency “2.45 GHz” and then its integration with a 3rd-order dipole antenna [1]. This design is followed by the creation of another efficient couple-resonant filter (CRF), in which each resonant grid is represented by a radiator. Moreover, a lossless two-port dipole antenna was introduced. Here, each of the poles is integrated with an inductor, to sure that the bipolar antennas can exploit as a resonator. The scores of the simulation-sketches and the computed results were convincing. Finally, the performance efficiency of the designed filter at the resonant frequency 2.45 GHz and for both “H-plane” and “E-plan” were summarized in Table 1.

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

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 S11) of 101% in the 2.3–7 GHz frequency range, high isolation (dB magnitude of S21), 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.

A Compact Eighth-Mode Circular SIW Cavity-Based MIMO Antenna

A verycompact and simple two-port multiple-input-multiple-output (MIMO) antenna is presented in this letter. The antenna element is designed based on the 1/8th mode modified circular substrate integrated waveguide cavity. The proposed MIMO antenna offers a bandwidth of 3.43% and resonates at 3.5 GHz. The isolation network consists of a single narrow linear half-wavelength slot and it offers a minimum isolation of 30 dB over the operating band. With a smaller physical area of 40 × 40 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , the proposed compact antenna offers a significant gain of 4.03 dBi. The envelope correlation coefficient values over the operational bandwidth are well within the accepted threshold limit. The proposed antenna is well suited for 5G wireless communication system applications. The design concept is further extended to a compact four-port MIMO antenna.

Research progress of adaptive optics in wireless optical communication system for Xi’an University of Technology

In chronological order, this paper summarizes the research progress and technical classification of adaptive optics technology in the application of wireless optical communication system at home and abroad. Then it introduces the work of Xi’an University of Technology in this field, including adaptive optics system with wavefront measurement, adaptive optics system with wavefront-less measurement, wavefront correction of liquid crystal spatial light modulator, wavefront correction of the combination of tilt mirror and deformable mirror, spatial optical fiber coupling adaptive optical wavefront correction, etc. The adaptive optics technology can effectively correct the distorted wavefront caused by atmospheric turbulence and improve the coupling efficiency and communication performance in wireless optical communication. Although these methods are not perfect in theoretical analysis and engineering practice, they can be regarded as useful exploration in this field.

State‐of‐art design aspects of wearable, mobile, and flexible antennas for modern communication wireless systems

SummaryIn this present contemporary epoch, wireless communication appliances exemplified meteoric progression in technology. These systems entail an antenna in every strand of communication. Depending upon the recent expansions in generations, the antennas become more compact, lightweight, portable, wearable, cost‐effective, and conformal while maintaining essential performance characteristics like impedance bandwidth, efficiency, gain, SAR, etc. This review is envisioned to unveil state‐of‐art in conventional and unconventional antenna technologies in recent times and offers knowledge to readers about a large regime of antenna designs suitable for different wireless communication system applications like GSM, GPS, Wi‐Fi, WLAN, bluetooth, 4G, and 5G under a single head. It is unambiguously worth stating that recent 5G antenna designs will unleash new breaks in leapfrogging all outmoded blockades in developments. Intended wireless communication systems take in mobiles, laptops, smart wears, tablets, etc., while antenna technologies cover wearable models, conformal structures, MIMO configurations, microstrip and planar monopole antennas. This study draws attention towards multi‐band and wide‐band accomplishment techniques, SAR analysis, bending and twisting effects of conformal or wearable antennas, effect of human body and wireless appliances on antenna performance. As per the study, FCC set a standard value of SAR as equal or below to 1.6 W/kg for 1 g of body tissue. IEC standards regulated a limit on SAR value as 2 W/kg, which is average value over 10 g of body tissue. Also, envelope correlation coefficient (ECC) of below 0.05, diversity gain of less than 10 dB and a maximum channel capacity of 0.4 bit/s/Hz are necessary for MIMO systems.

Research on application of GPS-based wireless communication system in highway landslide

Machine learning is a branch of the field of artificial intelligence. Deep learning is a complex machine learning algorithm that has unique advantages in image recognition, speech recognition, natural language processing, and industrial process control. Deep learning has It is widely used in the field of wireless communication. Prediction of geological disasters (such as landslides) is currently a difficult problem. Because landslides are difficult to detect in the early stage, this paper proposes a GPS-based wireless communication continuous detection system and applies it to landslide deformation monitoring to achieve early treatment and prevention. This article introduces the GPS multi-antenna detection system based on deep learning wireless communication, and introduces the time series analysis method and its application. The test results show that the GPS multi-antenna detection system of the wireless communication network has great advantages in response time, with high accuracy and small error. The horizontal accuracy is controlled at 0–2 mm and the vertical accuracy is about 1 mm. The analysis method is simple and efficient, and can obtain good results for short-term deformation prediction.

Accurate and broadband manipulations of harmonic amplitudes and phases to reach 256 QAM millimeter-wave wireless communications by time-domain digital coding metasurface

We propose a theoretical mechanism and new coding strategy to realize extremely accurate manipulations of nonlinear electromagnetic harmonics in ultrawide frequency band based on a time-domain digital coding metasurface (TDCM). Using the proposed mechanism and coding strategy, we design and fabricate a millimeter-wave (mmWave) TDCM, which is composed of reprogrammable meta-atoms embedded with positive-intrinsic-negative diodes. By controlling the duty ratios and time delays of the digital coding sequences loaded on a TDCM, experimental results show that both amplitudes and phases of different harmonics can be engineered at will simultaneously and precisely in broad frequency band from 22 to 33 GHz, even when the coding states are imperfect, which is in good agreement with theoretical calculations. Based on the fabricated high-performance TDCM, we further propose and experimentally realize a large-capacity mmWave wireless communication system, where 256 quadrature amplitude modulation, along with other schemes, is demonstrated. The new wireless communication system has a much simpler architecture than the currently used mmWave wireless systems, and hence can significantly reduce the hardware cost. We believe that the proposed method and system architecture can find vast application in future mmWave and terahertz-wave wireless communication and radar systems.

Research on Application of wireless Communication System in Middleware of Internet of Things

With the popularization of mobile communication technology and Internet of things, wireless data transmission operation occupies an important position. Massive data generated by the Internet of things system is applied to the Internet of things system by wireless communication network and wireless resource management. Wireless network communication technology is the use of radio waves for data transmission, is a new type of communication information system, for the future development of communication system has established the direction. The wireless communication system is introduced into the middleware of the Internet of things system to improve the security and reliability of the Internet of things and ensure the timely and effective dissemination of information and data in the Internet of things system.

Beam Tracking Using Least Mean Squares Algorithm for single-cell Massive MIMO Communication System

Millimetres wave (mm-wave) is an attractive option for high data rate applications in the 5G wireless communication systems that require proper beamforming and channel tracking. In this paper, we study, analyse and compare the performance of two closely related stochastic gradient descent-based approaches, namely the least mean square (LMS) algorithm, and the normalized least mean square (NLMS) algorithm, for tracking the transmit array beam in addition to the channel status. These adaptive filters usually result in a trade-off between convergence and accuracy. We found that the quality of the tracking results, measured in mean squared error (MSE) sense, are heavily dependent on the present step-the size of the gradient descent.

Bendable Microwave AlGaN/GaN High-Electron-Mobility Transistor With Output Power Density of 2.65 W/mm

Flexible radio frequency (RF) devices are in high demand for wearable electronics; however, they currently do not offer sufficient output power for application in fifth-generation wireless communication systems. This paper reports a bendable gallium nitride (GaN) high-electron-mobility-transistor (HEMT) with state-of-the-art output power in the microwave band. In this study, a fabrication method is proposed, where HEMT is originally grown on silicon carbide (SiC) substrates. After thinning the SiC substrates down to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5~\mu \text{m}$ </tex-math></inline-formula> , HEMT is transferred using a copper film rather than flexible substrates used in other studies. The measurements indicated that the fabricated devices exhibited a saturation output power of 2.65 W, corresponding to a power density of 2.65 W/mm, which was associated with maximum power added efficiency (PAE) of 51% at 3 GHz. The performance of the fabricated device remained stable even with a bending radius of up to 0.6 cm. These results indicated that the proposed fabrication method can potentially be used to realize high-power flexible RF electronics.

Time-varying Polarization-converting Programmable Metasurface and Its Application in Wireless Communication System

We propose a general scheme to manipulate fundamental and harmonic frequencies simultaneously in a nonlinear fashion based on time-varying polarization-converting programmable metasurface. Co-polarization and cross-polarization reflection can be switched dynamically at an operating frequency of 2.4 GHz by loading metasurface with PIN (p-i-n) diodes. As a result, by adjusting a duty cycle and frequency of square-wave-type time-varying signals used for time-varying modulation, energy distribution and frequency shift in the frequency domain can be manipulated. To verify this, we fabricated a sample and conducted experiments, and the results agreed well with the theoretical prediction, confirming the design principle. Furthermore, we propose a wireless communication system based on binary amplitude-shift keying as an example of its practical application. The proposed one eliminates the need for complex device components on the emitter because the information is directly modulated onto the metasurface, greatly simplifying the traditional system. The proposed system can achieve a maximum transmission data rate of up to 625 kbps in experiments. The proposed metasurface paves a new way for time-varying manipulation of microwave and can have potential in real-world applications, such as next-generation communication and high-resolution imaging.