Portable Communication 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.

Design and Analysis of Ultra-low Power Voltage Controlled Oscillator in Nanoscale Technologies

In latest wired and wireless communication equipment, VCO (voltage-controlled oscillator) is the major building block and particularly used as the stable high frequency clock generator. VCO performance is measured through frequency range, power supply used, area occupied, power consumption, delay, and phase noise. VCO is the cascaded of odd number of inverter stages in a ring format, hence it is also articulated as a ring oscillator. Today’s portable communication devices are battery operated. Hence, low power and area efficient designs play a key role in battery life enhancement and device size reduction. Device scaling improves the effective silicon area utilization, but it leads to more leakages. Therefore, low power techniques along with the technology scaling is the best way of low power designs. In this article, discussed various low power schemes. The ring oscillator designs are carried out in various nano meter scaled technologies such as 180nm, 90nm,65nm and 45nm. A 5-stage ring oscillator is implemented in each technology along with low power schemes, simulated in Cadence virtuoso, and noted power, delay, and area. Observed that the proposed ring oscillator with sleepy keeper technique generated a stable frequency of oscillations in the range of 1GHz-2GHz. A control voltage of 1.8V to 0.4V is applied and targeted the power less than 30mW and delay in 0.25p sec.

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.

The effect of step cooling treatment on the microstructure of Cu2ZnSnS4 film and its electric property

Flexible Cu2ZnSnS4 (CZTS) thin-film solar cells have the advantages of high flexibility, lightweight, and easy storage, which can provide portable and clean energy for various portable electronic and communication devices and vehicles. In this work, CZTS thin film deposited on flexible aluminum foil were prepared by vacuum magnetron sputtering and sulfide annealing in a tubular furnace. A step-by-step cooling way was applied to the annealing stage aiming at tuning the formation of CZTS, that is, when the slow cooling reached a target temperature (400 °C, 350 °C, 300 °C, 250 °C), a rapid cooling was triggered by opening the tube furnace lid. The effects of step cooling on the micro structure and property of CZTS film were studied by X-ray diffraction, Raman scattering, energy dispersive spectroscopy, scanning electron microscopy and current-voltage (I-V) characteristic curve test. The experimental results showed that all samples have CZTS phase and the Al/CZTS interface exhibited ohmic contact. And the formation of secondary phases like SnS, Sn2S3 and Cu31S16 in the sample film can be tuned by the step cooling treatments. The sample treated at 300 °C had the highest CZTS content, the average grain size of CZTS was 45 nm and the number of secondary phases was fewer. Beside, the I-V curve revealed that this sample had the lowest resistance. The experimental results in this work indicate the feasibility of Al as a substrate and back electrode for CZTS thin film.

Comparing outcomes with the cloud-based and portable versions of an open-source hearing aid

The open-source speech processing platform (OSP) is an open-source hearing aid (HA), developed to overcome proprietary restrictions of commercial HAs and pave the way for innovative HA technology through rigorous and reproducible research. This study evaluates portable and cloud-based platforms of the OSP that will enable a wide range of lab and field applications. The two platforms share common software applications for HA signal processing and objective outcome assessments (HO2). The cloud-based platform is hosted on a web server whereas the portable platform is accessed on a browser via a WiFi-enabled portable communication device. Listeners with mild to moderately severe hearing loss or normal hearing completed a word identification task (Modified Rhyme Test) in a 6-alternate forced choice paradigm using the HO2 app. Words were mixed with different levels of speech-shaped noise; presented via calibrated headphones or behind-the-ear receivers-in-the-canal for cloud-based and portable platforms, respectively. Signals were processed with individualized gain and compression ratios based on a clinically validated prescriptive formula. Results-to-date from four listeners show comparable range of word identification scores between platforms. The full dataset will also compare phoneme-level scores and response time measures generated from the HO2 app. Clinical research applications will be discussed. [Work supported by NIH-R44DC020406.]

Recent Advances in Pedestrian Inertial Navigation Based on Smartphone: A Review

Indoor location-based service is a hot research topic whose application market size is expected to grow from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\$ $ </tex-math></inline-formula> 41 billion by 2022 and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\$ $ </tex-math></inline-formula> 58 billion by 2023. As a portable communication device, smartphones have inherent advantages (such as being an essential gadget in daily life, embedding various sensors, and having powerful computing and storage ability), which provides a great opportunity for human activity recognition and pedestrian navigation. Smartphone-based pedestrian inertial navigation systems (PINSs) utilize measurements from inertial sensors embedded in smartphones to reckon the pedestrian’s location. Compared with other indoor position technologies, PINS has the advantage of autonomy and continuity, and can achieve high-precision positioning in a short period. Though various PINS methods based on the smartphone have been proposed, up-to-date review papers that summarize relevant technologies, methods, and solutions of PINS are relatively less so far in the literature. This article aims to provide an elaborated, timely, and valuable survey of different infrastructure-free pedestrian positioning and navigation techniques, including pedestrian inertial navigation methods, performance evaluation, and applications. Finally, current challenges and future research trends are discussed. This work propels a better understanding of existing pedestrian inertial positioning methods. It is helpful for researchers to further design and develop more accurate and robust pedestrian positioning and navigation systems based on inertial sensors embedded in the smartphone.

Visualizing electrical energy consumption with virtual augmented technology and the internet of things

Power consumption was considered one of the major expenses in households and small offices in the COVID pandemic situation. The proposed method employs virtual augmented technology and the Internet of Things (IoT) to provide a visual solution for monitoring the power consumption of electrical equipment. The IoT sensors are linked via mobile phones or portable communication devices. For the proposed work, the energy sensor devices are installed on the 4 single-phase electrical devices in the office room equipment. That equipment’s electrical consumption was saved, processed through the ESP8266 board, and then transmitted through WiFi to collect data on the cloud server. The saved electrical energy data in the dashboard can be displayed as a visual comparison with AR technology by using the mobile phone camera to scan the marker of each electrical device. The experimental results show that the value of electrical energy is accurate, and the data values can be used to manage the power consumption of electrical equipment.

Strategies to Improve Perioperative Communication During the COVID-19 Pandemic.

ABSTRACTThe coronavirus disease 2019 pandemic has led to a variety of challenges that have necessitated process changes in perioperative environments. Communication failures are a cause of surgical adverse events, and the pandemic has created additional communication concerns. Measures to prevent disease transmission, such as social distancing and wearing personal protective equipment, may inhibit communication. Relational dynamics and the types of collaboration that perioperative health care professionals exhibit can affect the quality of communication. The use of checklists during procedures and the hand‐over process may enhance communication content. Health care professionals can use communication tools, such as portable and fixed communication devices, an electronic display of the OR schedule, cyber‐physical systems, and short message service (ie, text messages) to facilitate information sharing. The concepts presented in this article should help perioperative nurses to improve communication during and after the pandemic.

A dual-band CPW-fed miniature planar antenna for S-, C-, WiMAX, WLAN, UWB, and X-band applications

A miniature planar antenna is a vital component of any portable wireless communication device. The antenna in portable devices should provide wide/multiple operating bands to cover a good number of narrowband services as a multi-band antenna not only reduces the number of antennas but also lessens the system complexity, cost, and device size. To operate over S-, C-, WiMAX, WLAN, UWB, and X-communication bands, in this paper, a dual-band CPW-fed antenna is presented. The anticipated antenna is made up of a vertical bow-tie-shaped patch and two asymmetric ground planes and etched on the same side of the single-sided standard substrate material. To generate two distinct operating bands, an inverted L-shaped parasitic element is inserted within the modified U-shaped coplanar ground plane. The antenna achieved dual operating bands of 3.24–8.29 GHz and 9.12–11.25 GHz in measurement which helps the proposed antenna to cover S-, C-, WiMAX, WLAN, 4G LTE, 5G sub-6 GHz, UWB, and X-communication bands. In the two operating bands, the antenna realized a peak gain of 4.33 dBi, and 4.80 dBi, the maximum radiation efficiency of 86.6%, and 72.6%, and exhibits symmetric radiation patterns. In the operating bands, the antenna also exhibits good time-domain behavior which helps it to transmit the signal with minimum distortion.

An asymmetric CPW‐fed modified bow tie‐shaped antenna with parasitic elements for ultra‐wideband applications

SummaryIn this paper, a modified bow tie‐shaped antenna for ultra‐wideband (UWB) communication applications is presented. The anticipated antenna consists of a CPW‐fed modified bow tie‐shaped patch and two asymmetric ground planes with dual parasitic elements. Electromagnetic computation on the antenna demonstrates that the patch and grounds are strongly linked, and the designed antenna can exhibit multiple resonances which overlap to reveal the UWB working spectrum. Experimental verification of the presented antenna shows that the antenna achieved a working band of 3.2–11.0 GHz, with a fractional bandwidth of 109.9%. The antenna also attained a peak gain of 4.32 dBi at 7.3 GHz and peak efficiency of 87.3% at 6.8 GHz and reveals excellent time‐domain behavior and omnidirectional radiation patterns throughout the operating band. A small‐size, large operating band, high gain and efficiency, high fidelity factor, omnidirectional radiation patterns, and very small group delay make the antenna ideal for portable communication devices in the UWB band.

A shorting-pin based compact meander multiband printed monopole antenna

The antenna presented in this work is based on a meandering monopole patch antenna with the incorporated shorting-pin technique for the realization of multiband antenna. The proposed antenna is printed on an FR4 with a footprint of 0.22λg×0.36λg at the lowest operating frequency. The antenna proposed demonstrated six resonances with suitable bandwidth as well as gain which make it suitable for WiMAX, LTE-A, aeronautical radio navigation, sub6GHz band for 5G, and WLAN applications. The prototype of the proposed antenna is fabricated, measured, and presented. The comparative analysis of the proposed antenna with the recently reported works shows that the proposed antenna outperformed its counterpart in terms of size and number of bands. Therefore, the antenna reported in this work is a suitable and promising candidate for future portable mobile communication devices.

Highly stretchable and sensitive strain sensor based on liquid metal composite for wearable sign language communication device

In recent years, the demand for wearable strain sensors is growing due to their motion monitoring and clinical data collection capabilities. The sensors with positive piozeconductivity, i.e. their conductivity increases when stretched, are more favored in wearable electronics because they can maintain high conductivity under stretching. However, reported composites with positive piezoconductivity mostly show low sensitivity. Furthermore, few wearable electronic systems based on strain sensors are built completely with data processing capabilities. Herein, we present a wearable sensor based on a positive piezoconductive composite composed of liquid metal microdroplets, metal microparticles, and elastic matrix. The resistance of the composite is extremely high at the relaxed state but drops drastically under any deformation. It has high stretchability (fracture strain >200%) and sensitivity (gauge factor ∼100), which shows excellent performance in detecting human motions such as joint bending. Based on this composite, we demonstrate a wearable and portable sign language communication device with a fully programmable and configurable system to help people with language disabilities communicate effectively with others from the visual and auditory perspectives. By bending the fingers, the device can type words or sentences on screen and speak relevant letters through the audio.

Coplanar waveguide-fed compact planar ultra-wideband antenna with inverted L-shaped and extended U-shaped ground for portable communication devices

To simultaneously cover multiple wireless services and protocols, the antenna in communication devices should operate over a wide and ultra-wide frequency band. The use of wide/ultra-wideband antennas not only lessens the number of antennas necessary to cover multiple frequency bands but also decreases the system complexity, size, and costs. To operate over the ultra-wide frequency band, in this paper a CPW-fed small antenna is reported for portable communication devices. The anticipated antenna comprises a bow-tie-shaped patch and two ground planes. One inverted L-shaped and one extended U-shaped ground plane are asymmetrically placed with the main radiator which helps the antenna prototype to realize a functional band of 3.05 – 11.25 GHz (VSWR ≤ 2). In the functional band, the studied antenna accomplished a maximum peak gain of 4.98 dBi and maximum efficiency of 94.4%. Moreover, it exhibits symmetric omnidirectional radiation patterns and good time-domain behavior. The lucrative characteristics such as simple design, very small size (24.5 × 20 mm2), ultra-wide operating band, good gain and efficiency, stable radiation characteristics, and good time-domain characteristics make it a potential candidate to be used in portable communication devices.

Random number generation from a quantum tunneling diode

Random numbers are important in many activities, including communication, encryption, science, gambling, finance, and decision making. There is a strong demand for a hardware random number generator that could support cryptographic applications. In this work, we propose a quantum tunneling diode as a source of true randomness achieved by applying electrical current sweeps through the device and then harnessing a time-counting unit to measure fluctuation of current flows. Our approach can be implemented with inexpensive electronics and could be integrated into systems that require random numbers such as portable communication devices.

Design and fabrication of compact triangular multiband microstrip patch antenna for C‐ and X‐band applications

SummaryModern portable communication devices require a compact antenna with superior performance and lower weight and size. The design and development of such a compact size antenna are a significant challenge for researchers. This proposed work compact slot‐based triangular patch antenna to work at the multiple resonance frequencies from 5 to 10 GHz using FR4 substrate is presented. The proposed antenna is simulated using High‐Frequency Structural Simulator (HFSS 2020R1). Simulated and fabricated antenna test results show that the proposed antenna can be suitably employed for the portable wireless transceivers in C and X bands. It has been inferred from the fabricated and measured results that the proposed slot‐based triangular patch antenna achieves the peak gain of 8 dBi and has excellent impedance matching properties such that return loss S11 is less than −10 dB and VSWR value is significantly closer to 1 at all the resonance frequencies.

An octa-band planar monopole antenna for portable communication devices

Due to the rapid development of wireless communication systems, good numbers of services and devices use different frequency bands and protocols. To concurrently cover all these services, the antenna in communication devices should operate over multiple frequency bands. The use of wide and multi-band antennas not only reduces the number of antennas necessary to cover multiple frequency bands but also lessens the system complexity, size, and costs. To operate over eight frequency bands to cover sixteen well-established narrow service bands, a planar monopole antenna is proposed for portable communication devices. The proposed antenna is comprised of an inverted F-shaped monopole patch with a rotated L-shaped strip and an F-shaped ground strip with a rotated L-shaped branch. The studied antenna can excite at multiple resonant modes which helps it to achieve eight measured operating bands of 789–921 MHz, 1367–1651 MHz, 1995–2360 MHz, 2968–3374 MHz, 3546–3707, 4091–4405 MHz, 4519–5062 MHz and 5355–6000 MHz. The achieved measured operating bands can cover sixteen popular narrow service bands for 4G/3G/2G, MWT, WiFi, WiMAX, WLAN, and sub-6 GHz 5G wireless communication system. The studied antenna achieved good gain, efficiency and exhibits stable radiation characteristics. Moreover, the antenna does not use any lumped element and left ample space for other circuitries which makes it easier to use in portable devices such as tablets, laptops, etc. with low manufacturing cost.

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.

High Performance Lithium Silicide Electrode Enable By Molecular Layer Deposition

The energy demand of our society is increasing without precedents. Lithium-Ion Batteries (LIBs) are and have been an enabler of the present communication revolution; LIBs are the powerhouse of portable communication devices. Consumers are starting to demand more sustainable and more environmentally friendly energy sources, energy production and distribution. To satisfy these demands, the next generation of rechargeable batteries will need higher specific energy and power (per mass) and energy and power density (per volume) than the current generation of LIBs. The current technology uses Lithium Metal Oxide (LMO) as positive electrodes and graphite as a negative electrode. This system has an energy density value ca. 250 WhL-1. To improve the power and energy density of the LIBs devices; new electrode material needs to be developed.Silicon (Si) has become one of the most investigated materials for LIB negative electrodes because of its ability to accommodate 3.75 moles of Li per mole of Si (Li15Si4), leading to a theoretical capacity of 3,579 mA h/g at room temperature1. While 372 mA h/g is the theoretical capacity for graphite2, this material can only accommodate 1 mole of Li per 6 mol of C.Despite Si advantages, progress towards a commercially available Si negative electrode has been impeded by their rapid capacity fade, poor rate capability, and low coulombic efficiency. The cause of electrode degradation is the Si volume change of ~300% upon lithium insertion and extraction3, presenting a major problem for electrochemical performance. The volume fluctuation damages the electrical contact between Si and the current collector, being too large to be controlled by currently developed coating technologies.One of the leading strategies established for the realization of such an approach is coating nano-Si particles with flexible materials to attempt to accommodate the volumetric changes of the particles. In this context, we propose to carry out a surface modification, in which Molecular Layer Deposition (MLD) is utilized to grow a mechanically robust, flexible coating, to undertake the Si expansion and contraction. For it, we have used TiCl4 molecule and as it is a relatively small molecule, when combined with the larger organic reactants, has high growth rates that are mainly limited by steric hindrance caused by the organic reactants. For these reasons, the recipe here developed is based on Glycerol and TiCl4 as the titanium precursor.The composition of the films was studied using Fourier-Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope-Energy-dispersive X-ray spectroscopy (SEM-EDX). Multiple characteristic absorption modes for both carbon and titanium related groups can be observed in the FTIR spectrum (Figure 1). These techniques confirm that the combination of both the carbon-related groups and the Ti absorptions providing evidence for the successful deposition of a hybrid organic-inorganic film showing that we are able to detect Ti in the surface of the electrode.Cyclic Voltammetry was used to characterize the electrochemical performance of the LixSi negative electrode coated with titanicone. We have successfully shown the deposition of titanicone on LixSi electrode and an initial electrochemical assessment of this electrode. These electrodes exhibit high capacity, around 2,000 mAhg-1 at 0.10C, and 270 mAhg-1 at 20C corroborating the goodness of the proposed methodology.Typical voltammogram shows the formation of the solid electrolyte interface, evident in the first cycle. In the subsequent scans, these peaks disappear (Figure 2). The sample exhibit the regular waves are corresponding to the Si redox reaction. Prosini PP, Cento C, Rufoloni A, Rondino F, Santoni A. A lithium-ion battery based on LiFePO4 and silicon nanowires. . 2015;269:93-97.Ikonen T, Nissinen T, Pohjalainen E, Sorsa O, Kallio T, Lehto VP. Electrochemically anodized porous silicon: Towards simple and affordable anode material for li-ion batteries. . 2017;7(1):7880.Zhao J, Lu Z, Liu N, Lee H, McDowell MT, Cui Y. Dry-air-stable lithium silicide and lithium oxide shell nanoparticles as high-capacity prelithiation reagents. . 2014;5:5088. Figure 1

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.

Mobile phones and "inattention" injuries: the risk is real.

Mobile phones though indispensable have a flip side: in fact, they adversely affect our ergonomics and mobility. They share an etiologic burden on the changed profile of inattention injuries; and now have proven to be a necessary evil in the changing lifestyles. We aimed to evaluate the role of mobile phones as a causative factor in these head and neck injuries. We evaluated various injury statistics published throughout the world that attributed the concurrence of neurological injuries to portable handheld communication devices. We evaluated the dangers posed by simultaneous engagement on phone and mobility and examined the impact on walking and field of view. We have also reviewed the current management strategies to combat this new mode of injury. The recent sensation Pokémon Go has been discussed as a case study of a spike in the incidence of injuries due to mobile phone use. Age >35 years old is a risk factor for mobile phone use and injuries as they have a higher chance of being distracted (81%) when compared to millennials (70% distracted). The highest incidence was that of head injuries being 33.1% of the estimated total followed by face, including eyelid, eye area, and nose (32.7%); and neck (12.5%). The most common injury diagnoses included laceration (26.3% of estimated total), contusion/abrasion (24.5%), and internal organ injury (18.4%). A heightened sense of self-protection and a multitasking attitude remains at the core of the trouble despite having knowledge of the required behavior. The health hazard of mobile phone use driving or walking needs to be highlighted with special emphasis on public education, law adherence, and technological solutions to mitigate the risk. The onus lies on the public as any technological advance would only work on the multitasking strategy and the price would be paid by the vulnerable road users.