Portable Wireless Devices Research Articles

An ultra-compact mechanical antenna based on PTFE highly charged electret for extremely low frequency communications

—Extremely-Low Frequencies (ELF, 30∼300Hz) transmitting antennas in wireless communications are often limited by antenna size and complex impedance matching networks. In this paper, we propose an ultra-small Artificial Electret Type Mechanical Antenna (AETMA), which is composed of a single charge electret and a driving structure, with high radiation efficiency and small size. In order to improve the electric dipole moment of the mechanical antenna, we employ a pin-plate corona polarization technique and a unidirectional stretching treatment to obtain a porous thin-film electret that can stably store a large amount of charge. Its surface charge density can reach 5.355 mC/m2 and we analyze its surface potential stability. To assess the radiation capability of AETMA, the radiation field models of three kinds of mechanical antennas are established and verified by simulation. Additionally, we simulate and compare the planar electret and curved electret configurations to determine the optimal form of AETMA. The radiation intensity of the planar electret is found to be superior under the same moment of inertia. Finally, a 1m-scale artificial electret antenna is designed based on the optimal model. Comparative analysis with existing rotary mechanical antenna schemes confirms the great potential of the proposed AETMA for portable, miniaturized and high-performance wireless communication devices.

An EEG motor imagery dataset for brain computer interface in acute stroke patients

The brain-computer interface (BCI) is a technology that involves direct communication with parts of the brain and has evolved rapidly in recent years; it has begun to be used in clinical practice, such as for patient rehabilitation. Patient electroencephalography (EEG) datasets are critical for algorithm optimization and clinical applications of BCIs but are rare at present. We collected data from 50 acute stroke patients with wireless portable saline EEG devices during the performance of two tasks: 1) imagining right-handed movements and 2) imagining left-handed movements. The dataset consists of four types of data: 1) the motor imagery instructions, 2) raw recording data, 3) pre-processed data after removing artefacts and other manipulations, and 4) patient characteristics. This is the first open dataset to address left- and right-handed motor imagery in acute stroke patients. We believe that the dataset will be very helpful for analysing brain activation and designing decoding methods that are more applicable for acute stroke patients, which will greatly facilitate research in the field of motor imagery-BCI.

High radiation performance and multi-band acoustically driven piezoelectric antenna based on energy trapping theory

The paper introduces a novel design method for an acoustically driven piezoelectric antenna with high radiation performance and broadband characteristics based on energy trapping theory. The reasonableness of the design method is demonstrated by analytically deriving the radiated magnetic field, radiated efficiency and resonant frequency, which are further validated by simulation analysis. Furthermore, a prototype is fabricated and measured, and the results indicate remarkable improvements compared to the non-energy trapping mode, the bandwidth is widened by 10%, the radiation efficiency is increased by 28%, the radiation magnetic field is increased by three times, the transmission distance is increased by 2.75 times. The radiation enhancement and multi-band capability of the proposed antenna has been successfully demonstrated. Additionally, we have successfully implemented amplitude modulation signals transmission using proposed antenna. These results highlight the significant potential of the proposed antenna for portable, miniaturized, and high-performance wireless communication devices.

Design and verification of a wearable wireless 64-channel high-resolution EEG acquisition system with wi-fi transmission.

Brain-computer interfaces (BCIs) allow communication between the brain and the external world. This type of technology has been extensively studied. However, BCI instruments with high signal quality are typically heavy and large. Thus, recording electroencephalography (EEG) signals is an inconvenient task. In recent years, system-on-chip (SoC) approaches have been integrated into BCI research, and sensors for wireless portable devices have been developed; however, there is still considerable work to be done. As neuroscience research has advanced, EEG signal analyses have come to require more accurate data. Due to the limited bandwidth of Bluetooth wireless transmission technology, EEG measurement systems with more than 16 channels must be used to reduce the sampling rate and prevent data loss. Therefore, the goal of this study was to develop a multichannel, high-resolution (24-bit), high-sampling-rate EEG BCI device that transmits signals via Wi-Fi. We believe that this system can be used in neuroscience research. The EEG acquisition system proposed in this work is based on a Cortex-M4 microcontroller with a Wi-Fi subsystem, providing a multichannel design and improved signal quality. This system is compatible with wet sensors, Ag/AgCl electrodes, and dry sensors. A LabVIEW-based user interface receives EEG data via Wi-Fi transmission and saves the raw data for offline analysis. In previous cognitive experiments, event tags have been communicated using Recommended Standard 232 (RS-232). The developed system was validated through event-related potential (ERP) and steady-state visually evoked potential (SSVEP) experiments. Our experimental results demonstrate that this system is suitable for recording EEG measurements and has potential in practical applications. The advantages of the developed system include its high sampling rate and high amplification. Additionally, in the future, Internet of Things (IoT) technology can be integrated into the system for remote real-time analysis or edge computing.

M-Commerce and its impact on Today's Economy

Mobile commerce, often known as m-commerce, comprises the use of wireless portable devices such as mobile phones and tablets to undertake online commercial transactions such as the purchase and selling of items, banking on the internet, and bill payment. The main difference is that customers do not need a laptop or PC to achieve this. They can make use of portable technologies such as cell phones and tablets. Users can now use online shopping sites and other internet services from anywhere and at any time. For example, when someone purchases any products if they have an Android or iOS app, they are engaging in m-commerce. A mobile device may be used to buy and sell a variety of content assets such as games, programmes, ringtones, subscriptions, and so on. Mobile commerce offers organisations extraordinary market potential, high productivity, as well as elevated profitability due to intrinsic properties such as ubiquity, personalisation, flexibility, and diffusion.

Improving the Performance of Paper-Based Dipole Antennas by Electromagnetic Flux Concentration.

One of the essential issues in modern advanced materials science is to design and manufacture flexible devices, in particular in the framework of the Internet of Things (IoT), to improve integration into applications. An antenna is an essential component of wireless communication modules and, in addition to flexibility, compact dimensions, printability, low cost, and environmentally friendlier production strategies, also represent relevant functional challenges. Concerning the antenna's performance, the optimization of the reflection coefficient and maximum range remain the key goals. In this context, this work reports on screen-printed paper@Ag-based antennas and optimizes their functional properties, with improvements in the reflection coefficient (S11) from -8 to -56 dB and maximum transmission range from 208 to 256 m, with the introduction of a PVA-Fe3O4@Ag magnetoactive layer into the antenna's structure. The incorporated magnetic nanostructures allow the optimization of the functional features of antennas with possible applications ranging from broadband arrays to portable wireless devices. In parallel, the use of printing technologies and sustainable materials represents a step toward more sustainable electronics.

CSRR loaded high gained 28/38GHz printed MIMO patch antenna array for 5G millimeter wave wireless devices

In this research paper, a new highly efficient compact size, dual-band 28/38GHz, 2 × 2 printed circuit board (PCB) based multi-input multi-output (MIMO) antenna array loaded with complementary Split Ring Resonator (CSRR) structure is simulated and fabricated for fifth-generation (5G) millimeter wave-based wireless devices. The Rogers RT/Duroid 6002 material within heigh 1.52 mm is being used as the substrate for the MIMO antenna array design. The CSRR metamaterial unit cells are positioned on the top and ground surface to improve the antenna's outcomes in terms of gain and directivity. The highly efficient CST microwave studio 2020 is used to design the MIMO antenna. It is noted from the results that the proposed single patch antenna is resonating on 28.06 GHz and 38.04 GHz with effective 15.81% and 14.58% impedance bandwidth at respective resonating bands. Then finally, the 2 × 2 MIMO antenna array having size (30 × 30 × 1.52) mm3 is developed from the proposed optimized antenna. The presented MIMO antenna array is tested by using the vector network analyzer (VNA). The measured results are compared with the simulated one and found that the optimized proposed MIMO antenna array is resonating at 28.29 GHz and 38.78 GHz with an effective reflection coefficient of −20.54 dB and − 35.81 dB respectively. It has a bandwidth of 15.30% and 13.97% and isolation of −24 dB and − 38.71 dB within respective resonating bands. It has achieved a realized gain of 8.65dBi and 8.24 dBi at 28 GHz and 38 GHz respectively. The ECC is <0.0041 between the MIMO antenna element. The developed MIMO antenna can be a good candidate for 5G millimeter wave-based wireless portable devices

AI-based quality of service optimization for multimedia transmission on Internet of Vehicles (IoV) systems

Multimedia Communications of Internet of Vehicles (IoV) uses WLAN, NFC and Fifth Generation networks. At the same time, in multimedia communications in healthcare, IoV's essential task is optimizing the quality of experience (QoE) via regulating wireless links between cars. In addition, the artificial intelligence (AI) method has revolutionized IoV's environment in total, and portable wireless devices have become highly essential to end consumers in their various activities for transferring multimedia material into IoV systems. Most consumers face their irritated and not-so-sufficient view of the performance, QoE. When the service delivery is not pleasurable, most customers can stop, and the market can eventually devalue the overall performance of a product, organization, or system as a whole. This article initially offers two new algorithms called Energy-aware QoE Optimization Algorithm (EQOA) and Queue aware QoE Optimization Algorithm (QQOA) and contrasts their results with Baseline. This article provides an alternative approach to these problems. Secondly, it presents a system for multimodal communication. Thirdly, multimedia IoV transmission through mobile devices offers the QoE Optimization Model. The experimental findings show that the proposed methods maximize QoE by delighting end-users service of mobile devices to levels greater than Baseline reference. Therefore, the suggested algorithms surpass the Baseline such that during multimedia transmission, they can be regarded as promising contenders for IoV implementations.

In-situ food spoilage monitoring using a wireless chemical receptor-conjugated graphene electronic nose

Monitoring food spoilage is one of the most effective methods for preventing food poisoning caused by biogenic amines or microbes. Therefore, various analytical techniques have been introduced to detect low concentrations of cadaverine (CV) and putrescine (PT), which are representative biogenic polyamines involved in food spoilage (5–8 ppm at the stage of initial decomposition after storage for 5 days at 5 °C and 17–186 ppm at the stage of advanced decomposition after storage for 7 days at 5 °C). Although previous methods showed selective CV and PT detection even at low concentrations, the use of these methods remains challenging in research areas that require in-situ, real-time, on-site monitoring. In this study, we demonstrated for the first time an in-situ high-performance chemical receptor-conjugated graphene electronic nose (CRGE-nose) whose limits of detection (LODs), 27.04 and 7.29 ppb, for CV and PT are up to 102 times more sensitive than those of conventional biogenic amine sensors. Specifically, the novel chemical receptors 2,7-bis(3-morpholinopropyl)benzo[lmn][3,8] phenanthroline-1,3,6,8(2H,7H)-tetraone (NaPhdiMor (NPM)) and 2,7-bis(2-((3-morpholinopropyl)amino)ethyl)benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetraone (NaPhdiEtAmMor (NPEAM)) were designed on the basis of density functional theory (DFT) calculations, and their interaction mechanism was characterized by a DFT 3D simulation. Interestingly, the CRGE-nose was connected on a micro sim chip substrate via wire bonding and then integrated into wireless portable devices, resulting in a cost-effective, high-performance prototype CRGE-nose device capable of on-site detection. The portable CRGE-nose can be used for in-situ monitoring of CV and PT concentration changes as low as 27.04 and 7.29 ppb in real meats such as pork, beef, lamb and chicken.

Reconfigurable a Dual-Port Multi-Band Antenna System with High Isolation Tuning Characteristics for Portable Wireless Devices

Reconfigurable a Dual-Port Multi-Band Antenna System with High Isolation Tuning Characteristics for Portable Wireless Devices

A dual impact driven frequency up-conversion piezoelectric energy harvester for ultralow-frequency and wide-bandwidth operation

In the view of the limitation of traditional frequency up-conversion piezoelectric energy harvesters (FUC-PEH) which has a narrow operating frequency range and is difficult to adapt to the ultralow frequency excitation, this study presents a dual impact driven FUC-PEH composed of two piezoelectric energy harvester units (PEHUs). The electromechanical model of the FUC-PEH is established based on the single degree of freedom system and piezoelectric coupling factor. An experimental prototype is made and tested under different excitation frequencies and accelerations. The dynamic characteristics and energy output characteristics of the system are analyzed by theoretical calculation and experimental tests. The results show that the proposed energy harvester can provide efficient energy output in a wide frequency range of 3.5 Hz–15 Hz under different excitation accelerations. When the excitation acceleration is 6 m/s2 and the excitation frequency is 9.8 Hz, the average output power of the lower PEHU across optimum load resistance can reach 1.17 mW. When the excitation frequency is 15 Hz, the average output power of the upper PEHU across optimum load resistance can reach 1.86 mW. The theoretical and experimental results show that the proposed energy harvester has potential for powering miniaturized wireless portable devices.

A novel quadband ultra miniaturized planar antenna with metallic vias and defected ground structure for portable devices

A novel heart-shaped monopole antenna used in wireless portable communication devices is proposed and discussed in this paper. The antenna has a radiant patch surface area of 28.504 mm2, the physical size of 15 × 12.5 × 1 mm3, and electrical dimensions of 0.095λ0 × 0.079λ0 × 0.006λ0, where λ0 denotes the wavelength of the free space at 1.89 GHz. Its prototype is printed on FR4 HTG-175, having a permittivity of 4.2 and a loss tangent of 0.019 at 1 GHz. The partial ground plane and two metallic vias connecting two open-ended branches of the slitted radiating patch to a parasitic conductor element results in about 98% miniaturization of the active patch area, as compared to the conventional antenna. The proposed antenna exhibits nearly an omnidirectional pattern in the elevation plane with a maximum radiation efficiency of 82.78% at 3.99 GHz, while a peak gain of 4.7 dBi is obtained at 6.5 GHz. The measured -6 dB impedance bandwidths demonstrate that the proposed quadband antenna operates in all the frequency bands of mobile telecommunication standards (2G/3G/4G/5G) and other applications, including WLAN, WiMAX, ISM, meteorological services, IEEE 802.11y, and C-band satellite communications. This antenna is easy to manufacture and can be used in most portable devices as a compact internal antenna. After simulating the modeled antenna using HFSS, a prototype was experimentally tested, and the measured results were compared with the data obtained by simulation. The parameters analyzed are return loss, bandwidth, and gain on all frequency bands. The fabricated prototype guarantees a minimum -10 dB bandwidth of 110 MHz and a maximum return loss of -12.2 dB, despite its low radiation efficiency of 21.43 % in the lower band dedicated to GSM applications. Furthermore, the proposed antenna operates as a narrowband and wideband.

A Switchable Polarization Slotted WLAN Antenna with DGS for IOT and Medical Applications

This work a 20 X 35 X 0.8 mm3 rectangular polarization reconfigurable antenna with four slots made at the corners of the patch. These four slots give the appropriate extra modes for circular polarization. Switching between LP and CP can be achieved using a PIN diode which is inserted across an L-shaped slit in the plane of the ground. The designed antenna is optimized and analyzed through simulations. The axial ratio (< 3 dB) bandwidth and impedance bandwidth (< -10 dB) are overlapped from 5.15 to 6.25 GHz (19.3%). The prototype antenna is tested for both states of the diode (forward and reverse bias). The working band covers the wireless local area network (IEEE 802.11a) band (5150 – 5350 MHz, 5725 – 5825 MHz) and HIPERLAN band (5450 – 5725 MHz) and a favorable compromise between simulated and tested outcomes. The omnidirectional radiation diagrams of the antenna are suitable for wireless portable medical devices.

ASIC Implementation of Linear Equalizer Using Adaptive FIR Filter

Power consumption plays a crucial role in the design of portable wireless communication devices, as it has a direct influence on the battery weight and volume required for operation. This article presents a novel design for a linear LMS equalizer for the optimization of filter order. The article describes the use of a variable length algorithm for dynamically updating the tap-length of the LMS adaptive filter to optimize the performance and for reducing the power in the adaptive filter core. An algorithm is applied to reduce and adjust the order of the filter in linear equalizer according to the channel conditions. The proposed design is implemented in the synopsis TSMC 65nm technology. The results from using the algorithm uses 28% less power when compared with the conventional 64-tap fixed length adaptive filter design. It has also been shown that the low-complexity of the additional circuitry needed for the variable length adaptive filter presents minimal overhead for this architecture.

Insights into Fabrication and Measurements of PCB-Based Passive Millimeter Wave Antennas

Future cellular communication systems might be based on millimeter wave frequencies. So, there is a need to design and deploy antennas which operate in the millimeter wave spectrum integrated in mobile terminals, portable wireless devices, base stations and access points. Even though a lot of articles exist on the design of such antennas, fabrication and measurement nuances of such antennas are addressed rarely in the open literature. Initially, the fabrication process of printed circuit board (PCB) antennas is discussed in detail with sources of error and possible precautions. A case study of microstrip-based tapered slot antenna operating at 28 GHz is presented. The variations in the antenna characteristics with slight variations due to fabrication errors are presented. A detailed discussion on S-parameters, pattern and gain measurements is also presented along with possible sources of errors associated with them.

Design and modelling of a compact circularly polarized antenna for RFID applications

In this article, a single-feed, miniaturized, circularly polarized (CP) microstrip patch antenna (MPA) using Koch fractal geometry for RFID applications is presented. The design consists of a probe-fed slotted square-shaped patch with the fractal edge and two pairs of capacitively coupled grounded metal strips. The proposed design methodology is validated by designing two prototypes (Antenna 1 and Antenna 2), which are operating at 2.435 GHz and 5.78 GHz respectively. Both antennas show right-hand circular polarization (RHCP) characteristics with 3 dB axial ratio bandwidth (ARBW) covering 2.433–2.439 GHz and 5.75–5.8 GHz respectively. This design leads to a reduction in the overall size of the antennas, to meet the demands of portable wireless devices.

Linearity improvement of RF mixer using double-linearization for 5 GHz applications

With 5G expected to roll out in 2020, the 5 GHz band will be sort after for sub-6 GHz 5G implementation. The feasibility of the wireless systems at 5 GHz will be primarily determined by the linearity of the RF down-converters in the receiver system. With growing battery-powered, portable, and wearable wireless devices, the task of achieving excellent linearity with low power consumption in RF down-converters is difficult. This work tries to overcome the difficulty by proposing a double-linearization (DL) based RF mixer. The proposed mixer circuit is designed using UMC 180 nm CMOS process libraries, and the post-layout simulations are carried out using Cadence SpectreRF in the presence of single-sideband phase noise. For a fundamental tone at 5 GHz and an interferer at 5.01 GHz, the proposed mixer using double-linearization achieves an input-referred third-order intercept point (IIP3) of 11.04 dBm, which is a 15 dB improvement over the IIP3 obtained before employing the proposed scheme. The proposed RF mixer circuit provides a conversion gain of 15.33 dB and an integrated double-sideband noise figure (DSB-NF) of 16.39 dB while consuming a low power of 1.5mW from a 1 V supply. The circuit also boasts an SFDR of 81.36 dB and IMR2 of 192.1 dB. The IIP3/mW ratio of the DL based mixer is 6.5 dB more than the recently proposed mixer topology. The layout of the proposed mixer consumes 0.57mm2.

FR-4 Substrate Based Modified Ultawideband Antenna with Gain Enhancement for Wireless Applications

A new circular shape patch ultrawideband (UWB) single feed microstrip antenna is described in this paper. The radiated patch of the proposed UWB antenna is embedded with slots to improve the radiation characteristics ensuring a wide impedance bandwidth. In the ground plane, two rectangular rings slots are etched to provide proper impedance matching over a wide frequency range. The proposed single layer UWB with overall dimensions of 55 mm by 56 mm is fabricated using low cost 4.3 relative permittivity FR-4 substrate. From results obtained, the antenna can provide an impedance bandwidth ranging from 2.2 GHz to more than 12 GHz (138%) that is wider than the standard UWB band. In addition, the modified UWB antenna can enhance the gain to more than 6.6 dB, which is higher than that achieved by the ordinary UWB antenna by more than 16%. Comparison of the modified UWB antenna simulated and measured results shows a close agreement, which enable it to be a promising solution for many wireless applications such as UWB applications, X-band (8-12GHz) satellite communication, portable wireless devices, medical applications, positioning systems cognitive radio and WiMAX 5.4 GHz band application.

Frequency reconfigurable lte antenna with u shaped open end for portable wireless devices

In this paper, a frequency tuning method for an U-shaped slot antenna for long term evaluation (LTE) wireless communication devices is presented and the performance of the antenna (return loss, total and radiation efficiencies…etc) is reported. The lower operating frequency of the antenna (700 - 960 MHz) is switched with different inductor loadings from 110 nH to 30 nH. The inductor component loads the U-slot antenna and thus enables to tune the frequency of low band (700 - 960 MHz). Higher bands (1710 - 2700 MHz) of the antenna remain unchanged with different inductor loadings. The impact of the inductor position is also investigated and the results are reported. The antenna presented in the paper is comparable with that of Cho-Kang Hsu’s publication. However, in Chos publication, only one low band is covered. In our design, all of existing commercial LTE frequency bands (Band 17 - Band 7) used in typical mobile devices are covered by the proposed antenna.

Research on the application of mobile e-commerce in ecotourism

Tourism is a comprehensive industry with strong relevance which has a profound connection with many industries of the national economy. As a coordinated result between human being and nature, ecotourism is being loved by more and more people. It has huge developing potentiality. Research on ecotourism can also promote ecological protection and sustainable development of the economy, which is an effective way to realize the harmonious development of economy and ecology. Due to the wide area, growing of self-help tour mode, the traditional e-Commerce is difficult to manage and provide suitable service in entire course of a tour. Tourists are most concerned about how to obtain information in the process of tourism, collect evidence in a timely manner, ensure the safety of them, improve service quality and meet personal satisfaction. Mobile E-Commerce is an expansion of E-Commerce with using portable wireless devices, and Mobile E-Commerce can provide personal service at any time in any place through wireless net. Mobile E-Commerce makes it possible that e-Commerce move with movable people. This article analyzes the necessities and superiorities of Mobile E-Commerce in ecotourism. Mobile E-Commerce can realize mobile information management, mobile marketing, mobile consumer relationship management etc. in ecotourism. First, the application of mobile e-commerce in ecotourism is investigated and evaluated with PEST analysis method. Then, through the analysis of Specific application mode of mobile e-commerce in ecotourism. Finally, it concludes that tourism is the most suitable product for mobile e-commerce, and the combination of the two can better promote the development of ecotourism and improve economic benefits.