Applications In Wireless Systems Research Articles

Usability testing of a wireless individual indicator system application: Monitoring exposure to outdoor air pollution among Malaysian Traffic Police.

ObjectivesDesigns for low-cost air monitors and associated performance data appear in many peer-reviewed articles; however, few manuscripts provide feedback from end user's experiences or comprehensive evaluation. The present study addresses the usability of the wireless outdoor individual exposure indicator system from the viewpoint of the Malaysian Traffic Police (end users). This study is one of the first to chronicle end user experiences for low-cost pollution sensing.MethodThe evaluation involved 12 target end users to assess the usability of a prototype for Malaysian Traffic Police to manage their exposure to outdoor air pollution. The test evaluation includes a pre-test, post-task and post-test questionnaire (Post-Study System Usability Questionnaire). The main components in this Post-Study System Usability Questionnaire are Overall satisfaction, System Usefulness, Information Quality and Interface Quality.FindingsThe results of the Post-Study System Usability Questionnaire indicated the mean score of the Overall satisfaction item (2.33), System Usefulness (2.25), Information Quality (2.36) and Interface Quality (2.17) on a scale of 1–10. Prototype users were satisfied with the system because the score is close to 1 on the Post-Study System Usability Questionnaire.ConclusionsA user-friendly wireless outdoor individual exposure indicator system is now available for Malaysian Traffic Police. Users have stated that they are happy to use the system at work. However, in addition to more technological advances, practical implementation requires evidence supporting its efficacy, viability and effectiveness.

Reconfigurable Filtenna using Varactor Diode for Wireless Applications

This paper presents a compact and planar reconfigurable filtenna for application in Wireless systems. The filtenna is composed of a UWB circular antenna and a filter with two trapezoidal resonators. The filter is integrated on the antenna feed line and has a band-pass frequency response. The filtenna frequency response reconfiguration is achieved by changing the capacitance of a varactor diode, placed between filter resonators; the capacitance varies continuously from 1.32 pF to 4.09 pF according to an applied bias voltage. The varactor capacitance analog variation defines the filtenna frequency of operation, which can be varied from 2.2 GHz to 3.4 GHz with an average bandwidth of 200 MHz, while maintaining the radiation characteristics of the UWB antenna. Simulated and measured filtenna results are shown according to varactor diode bias, demonstrating multiband operation using a compact planar design.

A Miniaturized Planar Monopole Antenna Based on a Coupling Structure for Compact Mobile Internet of Things (IoT) and Electric Vehicles (EVs) Device Applications in 5G, LTE, WLAN, WiMAX, Sirius/XM Radio, V2X, and DSRC Wireless Systems

A miniaturized internal antenna with monopole structure is constituted, including three radiating strips of a compact prototype and a back-coupling pad to improve the impedance matching, which achieves a wide bandwidth of 2.972 GHz between the operating frequencies of 2315–5285 MHz, and is introduced and researched. There is an urgent need for a complete frequency-continuous and large bandwidth design in the current wireless communication design to achieve a multimode, multifrequency, physical phenomenon design with large bandwidth and continuous operating frequency. The recommended antenna provides a broadband operation in an electric vehicles (EVs) and Internet of Things (IoT) devices application embedded in the wireless communication standard for 5G, LTE, V2X, WLAN, WiMAX, Sirius/XM Radio, V2X, and DSRC to support the multiband application. This design is embedded side edge of overall placement in the device and is integrated applicable to the trend of heterogeneous wireless multiple access networks in electric vehicle and Internet of Things system devices, which covered the 5G with supporting the band of n7/n38/n40/n53/n77/n78/n79/n90, the 4G with supporting the band of 7/38/40/41/42/43/48/67, the V2X and DSRC for the operating frequencies between 2500 and 5000 MHz, the Sirius/XM Radio for the operating frequencies of 2320–2345 MHz, the ISM band of WiFi and BT covering the band of 2450–2483.5 and 5150–5350 MHz, and the WiMAX also supporting the band of 2300–2690 and 3400–3690 MHz. Moreover, the compact antenna manufactured an FR4 material with the antenna area of 5 × 10 × 0.8 mm3 and the ground area of 33.5 × 10 × 0.8 mm3. The proposed design better benefits a narrow space on the PCB with a low profile and is easy to make with a circuit board design.

Perfectly matched inhomogeneous receiving metasurface for line source incidence

This paper presents a perfectly matched inhomogeneous receiving metasurface for line source incidence, based on the effective medium equivalency. Each building block of the inhomogeneous metasurface has effective constitutive parameters that satisfy a specific relationship dependent on the location of the line source. By doing so, the reflection from the receiving metasurface for the cylindrical wave incidence can be significantly suppressed, improving the total reception efficiency greatly. Theoretical analysis, numerical calculation, full-wave simulations and experimental results are consistent with each other, showing promising applications in some short-range wireless power transmission systems, where the incident wave is non-planar.

Broadband Instantaneous Multi-Frequency Measurement Based on a Fourier Domain Mode-Locked Laser

Broadband instantaneous multi-frequency measurement based on frequency-to-time mapping using a Fourier domain mode-locked (FDML) laser source is proposed and experimentally demonstrated. An electrically controlled silicon microdisk resonator (MDR) with an ultra-narrow linewidth of 60 pm (~7.5 GHz) functioning as a fast tunable optical filter is used to implement the FDML to generate a linearly chirped optical waveform (LCOW) with a wide frequency-sweeping range of 0.5 nm. The LCOW is then mixed at a modulator with a microwave signal with its frequency to be measured, detected at a low-speed photodetector (PD) and sent to a narrow bandpass filter (BPF). When the difference between the instantaneous frequency of the LCOW and that of the signal to be measured is equal to the center frequency of the BPF, a short-duration temporal signal is produced, and the time location of the temporal signal represents the frequency of the signal to be measured. A proof-of-concept experiment is carried out. Both single and multi-tone microwave frequency measurements are experimentally demonstrated. The measurement range is as large as 20 GHz with a measurement resolution of 200 MHz and an accuracy better than ±100 MHz. The proposed method showcases a new method for instantaneous frequency measurement (IFM) with high performance in terms of multi-frequency identification, real-time measurement, and high measurement speed compared with traditional approaches, which is attractive for applications in modern radar, electronic warfare, communication, and cognitive radio systems.

Machine Learning: A Catalyst for THz Wireless Networks

With the vision to transform the current wireless network into a cyber-physical intelligent platform capable of supporting bandwidth-hungry and latency-constrained applications, both academia and industry turned their attention to the development of artificial intelligence (AI) enabled terahertz (THz) wireless networks. In this article, we list the applications of THz wireless systems in the beyond fifth generation era and discuss their enabling technologies and fundamental challenges that can be formulated as AI problems. These problems are related to physical, medium/multiple access control, radio resource management, network and transport layer. For each of them, we report the AI approaches, which have been recognized as possible solutions in the technical literature, emphasizing their principles and limitations. Finally, we provide an insightful discussion concerning research gaps and possible future directions.

Anapole Meta-Atoms: Nonradiating Electric and Magnetic Sources.

The existence of classical nonradiating electromagnetic sources is one of the puzzling questions to date. Here, we investigate radiation properties of physical systems composed of a single ultrahigh permittivity dielectric hollow disk excited by electric or magnetic pointlike dipole antennas, placed inside the inner bore. Using analytical and numerical methods, we demonstrate that such systems can support anapole states with total suppression of far-field radiation and thereby exhibit the properties of electric or magnetic nonradiating sources. It is shown that the suppression of the far-field radiated power is a result of the destructive interference between radiative contributions of the pointlike dipole antennas and the corresponding induced dipole moments of the hollow disk. The experimental investigation of the nonradiating electric source has been performed to confirm our theoretical predictions. Our results pave the way to create and realize compact nonradiative sources for applications in modern wireless power transfer systems, sensors, RFID tags, and medical technologies.

Measurement Study of Real-Time Virtual Reality Contents Streaming over IEEE 802.11ac Wireless Links

Experience sharing among multiple users in virtual reality (VR) is one of the key applications in next generation wireless systems. In this VR application, one object can be reproduced as a virtual object based on recorded/captured multiple real-time images from multiple observation points. At this time, VR applications require a lot of bandwidth to provide seamless services to users in wireless links, and thus, a certain level of data rates should be maintained. As the number of users increases, the server allocates more data rates to users on top of the limited bandwidth in wireless networks. At this time, users who utilize the VR streaming services will suffer from a lower quality, due to the limited bandwidth. This paper reports the measurement study and also analyzes the fluctuations in terms of the data rates as the number of users increases while sharing point cloud information in real-time authorized reality environments over IEEE 802.11ac wireless networks. Moreover, it measures and analyzes fluctuations in terms of frames-per-second and Jitters, which are practical quality reduction indicators.

A Universal Power Management Strategy Based on Novel Sound‐Driven Triboelectric Nanogenerator and Its Fully Self‐Powered Wireless System Applications

AbstractWith the development of the Internet of Things (IoT), the power supply to trillions of IoT nodes has become a serious challenge. It is of significant importance to propose a rational power management scheme for constructing fully self‐powered systems using triboelectric nanogenerators (TENG). In this study, as inspired by an embroidery hoop, a new type of TENG without the Helmholtz resonant cavity is developed for collecting sound energy, which can generate the Voc and Isc up to 500 V and 124 µA, respectively at a resonance frequency of 170 Hz and sound pressure of 110 dB. Furthermore, the sound‐driven TENG integrated with a specially designed power management circuit derived from the universal power management strategy (PMS) can successfully drive a commercial narrow band‐IoT wireless node, which realizes periodic temperature and humidity data acquisition and transmission. With the same strategy, an electric switch and a temperature and humidity acquisition system based on Bluetooth technology can also be powered by a contact‐separated TENG and a wind‐driven TENG, demonstrating excellent versatility, adaptability, and universality of the PMS. This study provides a novel solution for the application of TENG in the field of low‐frequency IoT in local and wide areas.

Federated Multi-Armed Bandits

Federated multi-armed bandits (FMAB) is a new bandit paradigm that parallels the federated learning (FL) framework in supervised learning. It is inspired by practical applications in cognitive radio and recommender systems, and enjoys features that are analogous to FL. This paper proposes a general framework of FMAB and then studies two specific federated bandit models. We first study the approximate model where the heterogeneous local models are random realizations of the global model from an unknown distribution. This model introduces a new uncertainty of client sampling, as the global model may not be reliably learned even if the finite local models are perfectly known. Furthermore, this uncertainty cannot be quantified a priori without knowledge of the suboptimality gap. We solve the approximate model by proposing Federated Double UCB (Fed2-UCB), which constructs a novel “double UCB” principle accounting for uncertainties from both arm and client sampling. We show that gradually admitting new clients is critical in achieving an O(log(T)) regret while explicitly considering the communication loss. The exact model, where the global bandit model is the exact average of heterogeneous local models, is then studied as a special case. We show that, somewhat surprisingly, the order-optimal regret can be achieved independent of the number of clients with a careful choice of the update periodicity. Experiments using both synthetic and real-world datasets corroborate the theoretical analysis and demonstrate the effectiveness and efficiency of the proposed algorithms.

Wideband and Low-Profile Integrated Dual-Circularly-Polarized Transmit-Arrays Enabled by Antenna-Filter-Antenna Phase Shifting Cells

In this article, the theory, design, and demonstration of wideband and low-profile dual-circularly polarized (dual-CP) transmit arrays (TAs) are reported, which support independent beamforming for left-/right-handed CP waves. This is achieved by utilizing an antenna–filter–antenna configuration for the TA unit cells with a profile of only about <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.11\lambda _{0}$ </tex-math></inline-formula> , which consists of receiving and transmitting stacked patches connected by two microstrip delay lines. By utilizing the phase delay lines and unit cell rotation, the dynamic phase and the Berry phase can be simultaneously exploited for providing continuous dual-CP transmissive phase compensation insensitive to the angle of incidence. The diffraction analysis of a linear gradient array of the proposed cells confirms its wideband performance of abnormal refraction. In addition, broadband CP planar feed arrays were designed and verified for functioning as low-profile feeds with symmetrical patterns for the TAs. As proof-of-concept examples, two <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$K$ </tex-math></inline-formula> -band dual-CP TAs integrated with the planar feeds were synthesized, fabricated, and measured, possessing a total profile of about <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$7.1\lambda _{0}$ </tex-math></inline-formula> . The two prototypes offer either symmetrical or asymmetrical dual-CP beams over a wide bandwidth. Their measured peak gain is higher than 22 dBic, while the joint <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$S_{11} &lt; -15$ </tex-math></inline-formula> dB, axial ratio < 2 dB, beam squinting <3°, and 2–dB gain bandwidth is wider than 12%. The design methodology and the proposed dual-CP TAs are useful in communication systems for space and wireless applications.

Wireless fading channels performance based on Taylor expansion and compressed sensing: A comparative approach

SummaryThis paper addresses the performance of wireless fading channels, namely, Rayleigh, Rician, and Nakagami‐m fading channels, taking both noiseless and additive noisy cases into account. The performance metrics investigated are channel capacity, channel model variance estimation, required average description length based on Shannon entropy, and relative entropy and symbol error probability assessment. Taylor expansion is considered as an approximation for the aforementioned metrics together with the compressed sensing (CS) compressibility rule. Technical comments are provided for supporting simulation results. Mathematical interpretations are provided to support the simulation results along with feasible applications in 5G wireless systems. Conclusions and future research directions finalize the paper.

Novel design of a triple band PIFA antenna by using a binary genetic algorithm

In this study, we propose a miniature triple band PIFA antenna (planar inverted-F antenna) composed of uniform semi-patches for LTE2600/WLAN/WIMAX/HIPERLAN-2 applications. The binary genetic algorithm determines the shape of the antenna’s radiating plate to achieve multiband operation with good performance. The simulated results reveal that the proposed antenna has attained three bandwidths ( $$S_{11} <-\,10\mathrm{dB}$$ ). The first bandwidth is from 2.5 to 3.07 GHz with resonant frequency at 2.80 GHz. The second bandwidth takes the range from 3.79 to 3.99 GHz with an operating frequency at 3.89 GHz. The third bandwidth is from 5.64 to 5.94 GHz with resonance at 5.78 GHz. All three resonant frequencies demonstrate good impedance matching with high radiation efficiency and gain. The PIFA antenna design is constructed of two FR4 epoxy substrates and has dimensions of $$15 \times 30 \times 3.8\,\mathrm{mm}^3$$ . The proposed multiband PIFA antenna exhibits good performance with small size, making it suitable for several wireless systems applications.

Millimeter-Wave Dual-Band Bandpass Filter With Large Bandwidth Ratio Using GaAs-Based Integrated Passive Device Technology

In this letter, a millimeter-wave (mm-wave) dual-band bandpass filter is proposed with large bandwidth ratio by using gallium arsenide (GaAs)-based integrated passive device (IPD) technology. To realize small chip size, one dual-mode on-chip resonator is designed by using quasi-lumped capacitors and microstrip lines. In addition, multiple transmission zeroes are generated by further introducing both the electric and magnetic couplings between adjacent resonators. To realize large bandwidth ratio of two passbands, the external quality factors are investigated at both passband, and can be independently controlled. For demonstration, a 28-/50-GHz dual-band bandpass filter is designed, fabricated, and measured. The fractional bandwidth ratio is 7.8, which is much larger than the reported on-chip filters. Meanwhile, very low insertion loss of 0.58-dB is realized for the lower passband at 28 GHz, indicating the proposed dual-band bandpass filter a promising application in mm-wave wireless systems.

Garuda Vyuha based Microstrip patch antenna structure with high-gain for dual-band wireless applications

In this paper, a high-gain dual-band planar Microstrip patch antenna is designed to work at two different frequencies namely 5.6GHz and 7.4GHz. The antenna structure is in the form of Garuda Vyuha and has high directivity. The results propose that the Garuda Vyuha based antenna structure has very low profile and good polarization characteristics. The proposed antenna structure is simulated using ADS software and from the simulated results, the return loss is -15.094dB at 5.681GHz and -12.371dB at 7.337GHz. The Antenna operates at a bandwidth of 22MHz at 5.6GHz and 41MHZ at 7.4GHz. The Antenna provides a directivity of 5.921 at 5.6GHz and 6.2 at 7.4GHz. This antenna structure can be used for dual band applications in Wireless systems operating in these bands.

Ubiquitous Power Internet of Things and IPv6 Technology in Wireless Access Terminal and Intelligent Meter Reading Application System

State Grid Corporation of China (SGCC) has put forward the decision of building “three types and two networks”, which makes the energy Internet enterprises more competitive. With the goal of reaching the first-class level in the world, they are confident to meet greater challenges. To a certain extent, the power Internet of things has a great impact on the enterprises in the power industry, but also faces a huge impact and challenge. Based on the analysis of the current situation of China’s electric power enterprises, this paper puts forward the research of ubiquitous power Internet of things and IPv6 Technology in wireless access terminal and intelligent meter reading application system. Through the investigation and analysis of 180 staff of an electric power enterprise in China, this paper compares the cost, rationality and efficiency of traditional power mode and IPv6 technology power mode, and discusses and analyzes the results. It is concluded that after the introduction of IPv6 technology into the power industry, the cost of the enterprise is saved, the rationality of the structure is improved, and the benefit of the power enterprise is also significantly improved, which provides technical guarantee for the development of the power enterprise. The research in this paper has important practical significance for further promoting the application of ubiquitous power Internet of things and IPv6 Technology in wireless access terminal and intelligent meter reading application in power enterprises.

Switched-Biasing Techniques for CMOS Voltage-Controlled Oscillator.

A voltage-controlled oscillator (VCO) is a key component to generate high-speed clock of mixed-mode circuits and local oscillation signals of the frequency conversion in wired and wireless application systems. In particular, the recent evolution of new high-speed wireless systems in the millimeter-wave frequency band calls for the implementation of the VCO with high oscillation frequency and low close-in phase noise. The effect of the flicker noise on the phase noise of the VCO should be minimized because the flicker noise dramatically increases as the deep-submicron complementary metal-oxide-semiconductor (CMOS) process is scaled down, and the flicker corner frequency also increases, up to several MHz, in the up-to-date CMOS process. The flicker noise induced by the current source is a major factor affecting the phase noise of the VCO. Switched-biasing techniques have been proposed to minimize the effect of the flicker noise at the output of the VCO with biasing AC-coupled signals at the current source of the VCO. Reviewing the advantages and disadvantages reported in the previous studies, it is analyzed which topology to implement the switched-biasing technique is advantageous for improving the performance of the CMOS VCOs.

Mathematical framework for 5G‐UAV relay

AbstractUnmanned aerial vehicle's (UAVs) small size, long‐lasting battery, and flexible trajectory have produced widespread applications in radio communication systems, especially its usage as a cellular tower (gNB) for 5G services. At the same time, the mmWave's enormous available bandwidth makes it the primary contender for next‐generation communication networks. This article aims to synthesize and assess the usage of mmWave concurrently in backhaul and access links for amplify‐and‐forward (AF) relay installed on the UAV. A mathematical framework is developed for the received power of the user equipment (UE) obtained in relay path (gNB‐UAV‐UE) and direct path (gNB‐UE) via; (i) free space, and (ii) log‐distance path loss model. The International Telecommunication Union recommended city model is used to assess the likelihood for LoS and NLoS paths in four urban environments; (i) high‐rise urban, (ii) dense urban, (iii) urban, and (iv) suburban. Furthermore, various parameters, that is, UAV's position and amplification factor are stipulated to optimize the efficiency of a UAV‐based AF relay for enhanced users coverage.

Dual Loop Reactive Shield Application of Wireless Power Transfer System for Leakage Magnetic Field Reduction and Efficiency Enhancement

The wireless power transfer (WPT) system generates a high density leakage electromagnetic field (EMF) during its operation. Exposure to leakage EMF has adverse effects on human health. In order to reduce the leakage EMF, a shielding method can be applied to the WPT system. The shielding methods in previous studies reduced leakage EMF, but the power transfer efficiency (PTE) of the WPT system was decreased. Therefore, a shielding method providing high shielding effectiveness (SE) without PTE degradation is necessary. This paper proposes a dual loop reactive shield application for reducing leakage EMF with PTE enhancement. The proposed dual loop reactive shield generates in phase and out of phase magnetic fields simultaneously. The out of phase magnetic field depresses leakage EMF, and the in phase magnetic field increases the PTE. The proposed method is verified for the cases of symmetric and asymmetric WPT systems, including misalignment conditions. The experimental results of the symmetric WPT system showed a 2.1% PTE increase with 55.5% SE in an alignment condition, and a 3.9% PTE increase with 53% SE in a misalignment condition. In addition, the experimental results of the asymmetric WPT system presented a 1.6% PTE increase with 61.3% SE in an alignment condition, and a 2.7% PTE increase with 54.1% SE in a misalignment condition.

A New Approach for Enhancing the Services of the 5G Mobile Network and IOT-Related Communication Devices Using Wavelet-OFDM and Its Applications in Healthcare

The heart of the current wireless communication systems (including 5G) is the Fourier transform-based orthogonal frequency division multiplex (OFDM). Over time, a lot of research has proposed the wavelet transform-based OFDM as a better replacement of Fourier in the physical layer solutions because of its performance and ability to support network-intensive applications such as the Internet of Things (IoT). In this paper, we weigh the wavelet transform performances against the future wireless application system requirements and propose guidelines and approaches for wavelet applications in 5G waveform design. This is followed by a detailed impact on healthcare. Using an image as the test data, a comprehensive performance comparison between Fourier transform and various wavelet transforms has been done considering the following 5G key performance indicators (KPIs): energy efficiency, modulation and demodulation complexity, reliability, latency, spectral efficiency, effect of transmission/reception under asynchronous transmission, and robustness to time-/frequency-selective channels. Finally, the guidelines for wavelet transform use are presented. The guidelines are sufficient to serve as approaches for tradeoffs and also as the guide for further developments.