Wireless Communication Devices Research Articles

New RSA Encryption Mechanism Using One-Time Encryption Keys and Unpredictable Bio-Signal for Wireless Communication Devices

Applying the data encryption method used in conventional personal computers (PC) to wireless communication devices such as IoT is not trivial. Because IoT equipment is extremely slow in transferring data and has a small hardware area compared with PCs, it is difficult to transfer large data and perform complicated operations. In particular, it is difficult to apply the RSA encryption method to wireless communication devices because it guarantees the stability of data encryption because it is difficult to factor extremely large prime numbers. Furthermore, it has become even more difficult to apply the RSA encryption method to IoT devices as a paper recently published indicated that it enables rapid fractional decomposition when using RSA encryption with a prime number generated through several pseudo-random number generators. To compensate for the disadvantages of RSA encryption, we propose a method that significantly reduces the encryption key using a true prime random number generator (TPRNG), which generates a prime number that cannot be predicted through bio-signals, and a disposable RSA encryption key. TPRNG has been verified by the National Institute of Standards and Technology. The NIST test and an RSA algorithm are implemented through Verilog.

Polarization and Frequency-Selective Surface for Vehicular Beamforming Communications Requiring Near-Zero Profile

A polarization-selective and reconfigurable Fresnel zone plate consisting of frequency selective surfaces (FSS) loaded with varactor diodes is devised for compact vehicular wireless communication devices. The unit cell constituting the impedance zone exhibits rapid impedance transitions from 0 ohm (electrically-opaque) to 377 ohm (electrically-transparent). An I-shape configuration is employed for the resonant unit cell structure, featuring high compatibility with DC bias voltage network. In addition, double-sided FSS is employed on the top and bottom faces for polarization-selective beamforming. The FSS comprise of a dielectric with near zero thickness ( λ /250 of 2.40 GHz) resulting in intentionally high mutual coupling between the layers. The devised unit cell is designed using an equivalent circuit model analysis and optimized using finite element solver, achieving over 30 dB impedance switching. The proposed unit cell is experimentally confirmed in both vertical and horizontal polarizations. By configuring the DC voltage bias lines, the unit cells of the FSS are transformed into electrically-driven impedance zones formulating alternating and repetitive gratings. The width and the interval of the grating manipulate the constructive and destructive interference resulting in beam scanning range of 30° in both vertical and horizontal polarizations. The proposed approach can provide concise and compact beamforming solutions for future vehicular communications.

Design and simulation of a rectangular patch microstrip antenna for the frequency of 28 GHz in 5G technology

The development and application of the fifth generation mobile communication system (5G) requires and provides high-speed and high-capacity wireless communication services. This paper describes the design of small antennas using microstrip technology as a wireless communication device operating at a frequency of 28 GHz. The technique method used for antenna design is inset feed technique with a shift to the length of the transmission line on the side of the patch gap. Antenna design is used method of moment or simulation using CST software application. To support antenna design in the simulation process using the type of material substrates used was Taconic TLY-5 type. The results of simulations the obtained, such as: bandwidth of return loss ≤ -10 dB is 454 MHz, VSWR (2:1) is 1.03, beam width is 74.4 degrees and gain is 6.72dB. An antenna design obtained through simulation shows a simple and compact antenna shape with the expected parameter value. The design is a basic element of research for antenna sub arrays for increasing radiation power.

Experience Blocking Ratio Based Game Theoretic Approach for Spectrum Sharing in Heterogeneous Networks

With the rapid developments of wireless communication and mobile devices, heterogeneous networks have emerged as a promising paradigm to provide users with various services in Internet of Things (IoTs). However, due to the limited resources, the spectrum sharing in heterogeneous networks becomes a new challenge. Therefore, in this paper we present an experience blocking (EB) ratio based game-theoretic approach for spectrum sharing in heterogeneous networks where the small cell can rent the spare spectrum from the macro cell. Specifically, first, a novel EB ratio based model is proposed to evaluate the efficiency of spectrum usage in a cell. Then, the Stackelberg game with one leader and one/multiple followers is used to formulate the interaction between macro cell and one/multiple small cells. With the game theoretic model based on the EB ratio, the macro cell can determine the optimal price for leasing spectrum, whereas small cells can optimize the cost to rent. Finally, an EB table is given to evaluate the blocking status of a cell and simulation results show that the proposed scheme can improve the efficiency of spectrum sharing better than other schemes.

Through-the-Wall Image Reconstruction via Reweighted Total Variation and Prior Information in Radio Tomographic Imaging

This paper focuses on the application of radio tomographic imaging in through-the-wall image reconstruction. By using the simple wireless communication devices, e.g., Wi-Fi cards, the whole building layout can be reconstructed with only the received signal strength (RSS). For the reconstruction algorithms, the total variation (TV) minimization algorithm has been used to reconstruct the image. However, some false artifacts may exist in the image results due to the inherent defects of the algorithm. The artifacts can be misestimated as wall structures. In this paper, a reweighted total variation and prior information regularization algorithm named as RTV-PIR is proposed to reconstruct the image. This algorithm is based on the TV minimization of the image. And the prior information that the wall is only oriented horizontally or vertically is also considered simultaneously, which is used to keep the wall orientation. To verify the performance of the proposed algorithm, the simulations and experiments based on real data are conducted. It is shown that the RTV-PIR algorithm can get a better result with respect to the root mean square error (RMSE) and the structural similarity (SSIM), in comparison with the state-of-the-art algorithms.

Rational design of hollow nanosphere γ-Fe2O3/MWCNTs composites with enhanced electromagnetic wave absorption

High-performance electromagnetic wave (EMW) absorbing materials have been widely used in the wireless communication and electronic devices due to their important potentials in electromagnetic attenuation. However, it is difficult to develop carbon-based absorbers with thin thickness, lightweight, and low filler loading. In this work, rationally designed hollow nanosphere γ-Fe2O3/MWCNTs composites were successfully realized for ultrathin, lightweight, and high-efficiency EMW absorbers. It showed that the composition, microstructure, and morphology of composites were tailored, which gave rise to the tunable magnetic behavior, porosity, and electromagnetic parameters. The rational design of composition and novel structure contributed to the optimization of the impedance match. The EMW attenuation was enhanced by the synergistic effects of the dielectric loss originated from the interfacial and dipole polarization, conductive loss stemmed from the 3D conductive network, and the magnetic loss derived from the eddy-current loss and ferromagnetic resonance. Accordingly, the hollow nanosphere γ-Fe2O3/MWCNTs composites with a low filling ratio of 20 wt% achieved an ultrathin matching thickness of 1.4 mm and a strong reflection loss of −63.6 dB. The substantially enhanced EMW absorbing performances were owing to the optimized impedance matching and enhanced attenuation capability. Therefore, this work can provide a paradigm for the design and synthesis of hollow nanosphere γ-Fe2O3/MWCNTs composites with an enhanced EMW absorption.

A Compact Triple-Notch Band Ultra-Wideband Antenna

This paper proposed a compact ultra-wideband (UWB) antenna (17.5 × 20.5 mm2) with a triple-notch band characteristic to overcome the interference caused by the three narrow frequency bands that coexist within the ultra-wideband frequency ranging from 3.1 to 10.6 GHz as stipulated by the Federal Communication Commission (FCC). Two slots on the radiating patch and a copper trace on the ground plane of the antenna were introduced to reject the WiMAX, WLAN and SHF frequency bands. The dimensions of the slots and copper trace are optimized to achieve the desired band rejections. The compact size of the antenna is in line with the miniaturization requirement of modern wireless communication devices but at the same time is able to support multiple wireless communication services. The simulation result shows that the antenna can function over the UWB frequency range but with band rejections on the WiMAX band (from 3.2 GHz to 3.6 GHz, WLAN band) (from 5.15 GHz to 5.85 GHz) and SHF band (from 7.25 GHz to 8.395 GHz). The proposed antennas are simulated and designed in CST Microwave Studio® software and fabricated on a FR-4 substrate with a relative dielectric constant, er of 4.5, loss tangent, tan δ of 0.019 and thickness, h of 1.6 mm.

Location assisted delay-less service discovery method for IoT environments

Location aided services (LAS) is a significant demand for wireless communication devices for service discovery and resource utilization in internet of things (IoT) environments. IoT devices provide services that are more significant about location and cost efficiency for both privacy and communication. In this paper, a location assisted delay-less service discovery (LDSD) for IoT users is introduced to minimize request–response delays. The proposed service discovery method searches cost effective resource for serving user requests with the knowledge of the resource location. With the knowledge of the location, LDSD classifies the resources based on service request delivery delay and availability for speedy resource mapping and service response. This resource discovery is also facilitated for replicated resource mapping considering service cost and request delivery delay ensuring minimum resource replication The performance of the proposed LDSD is verified through experiments and the benefit of the discovery method is assessed using the metrics: response time, failure rate, resource utilization, request delivery time, resource availability and service latency. Experimental results demonstrate the reliability of the proposed LDSD by minimizing response time, failure rate, request delivery time and service latency and improving resource utilization and availability.

Bsense: Practical Cross-Technology Communication Utilizing Beacon Frames of Commodity WiFi APs

A considerable number of wireless communication devices can share a single radio frequency. Cross-technology communication is a novel approach that enables direct communication between heterogeneous communication devices that share a limited frequency. This article presents Bsense, a solution designed for practical cross-technology communication. We first investigate the empirical challenges to such a technology in the real world. Bsense offers practical solutions to overcome these challenges without specialized hardware or standards modification. The key concept of Bsense is to distinguish between symbols using differences in the signal strength or the signal length of periodic IEEE 802.11 beacons. We have implemented Bsense on a commodity WiFi access point and CC2650 SensorTag. Real-world experimental evaluations in terms of throughput, symbol error rate, and duty cycle demonstrate that Bsense provides sufficient performance for practical cross-technology communication. Bsense is expected to be applicable to new IoT applications because of its compatibility and applicable performance with respect to commodity communication technologies.

Generation of wideband vortex beam with different OAM modes using third-order meta-frequency selective surface.

Orbital angular momentum (OAM) beam generators have attracted tremendous interests recently due to their excellent performance and potential applications in wireless communication. However, the existing transmissive OAM generators suffer from several limitations, such as narrow bandwidth, high profile and low efficiency. In this study, a new wideband third-order meta-frequency selective surface (meta-FSS) for generating focusing vortex beam is developed. The proposed meta-FSS element is designed at X- band with a third-order band-pass filter property, which exhibits the merits of low profile, high transmissivity, and large angular stability. By employing the proposed meta-FSS element, prototypes of OAM generators for + 1 and -2 modes are designed, fabricated, and measured. Experimental results verify the ability of the proposed design to convert an incident left/right-handed circularly polarized (L/RHCP) spherical wave into a transmitted R/LHCP vortex carrying OAM wave from 9.0 GHz to 11.0 GHz with high mode purity. A good agreement is achieved between the experimental and numerical results, which demonstrates that the proposed structure paves the wave for generating desired OAM modes, and provides new possibility for designing novel low-profile wireless communication devices.

Influence of Ho–Ni–Mn substitution on the structural and magnetic behavior of Ba–Sr Co2Z-type nanohexaferrites extension up to Mossbauer investigations

A series of Co2Z-type Ba–Sr nanohexaferrites Ba1.5Sr1.5Co2−zHozMnxNiyFe24−x−yO41 (z = 0.0, 0.05, 0.10, 0.15, 0.20, x = y = 0.0, 0.25, 0.5, 0.75, 1.00) have been synthesized using sol–gel auto-combustion synthesis route. The effect of Ho–Ni–Mn substitutions on crystallographic and magnetic properties of synthesized nanohexaferrites was investigated using XRD, VSM, and Mossbauer spectroscopy. Microstructural analysis showed single-phase crystal structures without any impurities and hexagonal with the space group P63/mmc. The average variation in crystallite size ranges from 43 to 60 nm with a slight increase in X-ray density and appreciable decrease in porosity was observed for different dopants. FE-SEM (Nova Nano SEM-450) substantiates the hexagonal structure and HR-TEM images assisted with SAED pattern confirm the crystalline quality and FWHM of the material, which significantly support the XRD results. FTIR spectra showed two characteristic metal stretching peaks in the range of 400–600 cm−1 due to the substitution of Ho–Ni–Mn. Magnetic measurements show maximum magnetic saturation (Ms) at 44.04 emu g−1 and elevated value of coercivity (Hc) 224Oe imparting typical characteristics of soft ferrite with high coercivity. Mossbauer analysis with least squares fit sextets of six distinguishable sites at room temperature for all samples substantially supports the results of VSM. The materials with large coercivity are useful in permanent magnet applications. The prepared composites could be useful for applications in microwave absorbing materials, magnetic storage, and the miniaturization of antennas for wireless communication devices.

Environmental radiofrequency electromagnetic field levels in a department of pediatrics

Preterm neonates constitute a vulnerable population that is highly sensitive to its environment. Given the increased use of wireless communication devices (mobile and digital enhanced cordless telecommunications, WiFi networks, etc.), neonates hospitalized in a department of pediatrics are potentially exposed to radiofrequency electromagnetic fields (RF-EMF). Strikingly, data on RF-EMF levels in pediatric units have not previously been published.The objective of the present study was thus to quantify the RF-EMF levels in a 34-bed tertiary department of pediatrics with a neonatal critical care unit (NCCU) and a neonatal intensive care unit (NICU). To this end, we used triaxle antenna dosimeters to map the RF-EMF levels in the environment and to measure spot emissions from medical devices. In a first set of experiments, RF-EMF levels at 144 points in the staff area and in the children's rooms in the NCCU and NICU were evaluated over a 24-h period. In a second set of measurements performed in a Faraday chamber, we measured the RF-EMF levels emitted by the medical devices to which neonates are potentially exposed in the department of pediatrics.The RF-EMF levels were significantly higher in the NCCU than in the NICU (p < 0.05). Although the two units did not differ significantly with regard to the average maximum values, the single greatest value recorded in the NCCU (6 V/m GSM + UMTS 900 (UL) frequency band, in the staff area) was more than twice that recorded in the NICU (3.70 V/m in the UMTS 2100 (UL) frequency band, in the children's rooms). The NCCU and NICU did not differ significantly with regard to the time during which the RF-EMF level at each measurement point was more than two standard deviations above its mean. The RF-EMF level was significantly higher during the day than during the night (p < 0.001). The various medical devices used in the NICU did not emit detectable amounts of RF.Overall, RF-EMF levels in the NCCU and NICU were very low. It is probable that the RF-EMFs measured here were primarily generated by the parents' and staff members' activities, rather than by medical devices. However, a combination of low-level, chronic exposure with transient, elevated peak values in a vulnerable population of preterm neonates may be of particular concern. In a department of pediatrics, decreasing preterm neonates’ exposure to RF-EMFs should primarily involve a limitation on the use of wireless communication devices by staff members and parents.

1156. Running on Empty: Enlisting Transportation Services in Quality Improvement Initiatives as a Safeguard Against Catheter-Associated Urinary Tract Infections

BackgroundPatient transportation for off unit procedures is associated with transfers from bed to chair to examination tables, frequent elevation of the urine collection bag (UCB) above the bladder and urinary reflux (UR) of bacteria-laden urine into the bladder, significantly increasing risks of catheter-associated urinary tract infection (CAUTIs). If UCBs were systematically emptied prior to transportation the likelihood of UR would be greatly diminished, potentially reducing CAUTIs.MethodsDuring a 5-week period transportation services (TS) collected baseline data on UCB status of all ICU patients, classifying them as empty/good to go vs. full/not good to go (Phase 1). Then, TS were educated on the importance of reducing UR as part of CAUTI reduction and were empowered to request UCBs be emptied. In parallel, unit-based staff were instructed to drain CBs prior to patient transport off unit and to expect the TS would refuse transport if CB was not emptied (Figure 1). Wireless voice-activated communications devices were used to improve coordination between TS and unit staff. During a 3 month (Phase 2) period, TS again collected data on the UCB status of ICU patients while reinforcing the need to empty UCBs.ResultsAt baseline it was a coin toss as to whether a patient’s UCB would be empty or full at the time of transportation, while over 90% of UCB were emptied in Phase 2 (47.1% and 52.9%, vs. 90.6% and 9.4%, empty and unemptied in Phase 1 and Phase 2, respectfully, P < 0.001) (Figure 2). Figure 3 shows the detailed UCB status (empty at TS arrival, emptied upon TS request, transported full, transport refused) during Phase 2, with significant month upon month improvements (P = 0.014).ConclusionDespite longstanding existing hospital policies promoting best practices, including the need to empty UCBs prior to transport, we found this was commonly ignored in usual practice. Recruiting the TS to enforce UCBs are empty at the time of transportation proved a very effective way to markedly improve best practices. If representative of general practices elsewhere, this suggests leveraging TS can help ensure UCBs are emptied prior to patient transport and reduce CAUTI risk. It also exemplifies how ancillary services can be recruited to play an active role in quality improvement/patient safety projects. Disclosures All authors: No reported disclosures.

Isolation Improvement of an Overlapped Two-element MIMO Antenna

An overlapped two-element antenna structure with excellent compactness is proposed. Extraordinarily strong mutual coupling is effectively mitigated by a decoupling network with simple coupled microstrip lines connected to the antennas in shunt. Simulation example and results are demonstrated. The isolation improvement is better than 8 dB (from about 2 dB to over 10 dB) in most of the Wi-Fi 2.4 GHz band. Four lumped components networks are utilized to maintain the good impedance matching before and after decoupling, and the return loss is higher than 7 dB over the band of interest. Remarkable decrease in envelope correlation coefficient (ECC) in most of the working band is achieved. All these performances prove the presented antenna structure and decoupling scheme a promising option for those mobile terminals and wireless communication devices which have high data rate and compact volumes.

Guest Editorial

Radio and Wireless Week (RWW) has emerged as the flagship winter meeting point of the IEEE Microwave Theory and Techniques Society (MTT-S). Its last edition was held in Orlando (Rosen Plaza Hotel), FL, USA, on January 20–23, 2019, and consisted of five related conferences in a four-day event that focused on the intersection between wireless communication theory, systems, circuits, and device technologies, and emerging applications, including RF wireless sensing. It resulted in a unique forum for engineers and practitioners to exchange their ideas about main RF technologies and techniques for the state-of-the-art wireless systems and their end-use applications. In particular, RWW 2019 was composed of the Radio and Wireless Symposium (RWS), the Topical Conference on Power Amplifiers for Wireless and Radio Applications (PAWR), the Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems (SIRF), the Topical Conference on Wireless Sensors and Sensor Networks (WiSNet), and the Topical Workshop on the Internet of Space (TWIoS). This was the first year that the RWW was co-located with the ARFTG Microwave Measurement Conference, as the premier forum in RF, microwave, and millimeter-wave measurements, calibration, and uncertainty, as well as with the IEEE Internet-of-Things (IoT) Summit, to bring together researchers, policy makers, and companies in the Internet-of-Space (IoS) sector.

Efficient Identity-based Signature Scheme with Message Recovery

Digital signature is one of the important primitive of public-key cryptography and has become an essential technique in providing security services in modern communications. Due to the limitations imposed by both the communication bandwidth and computational power of wireless communication devices, signature schemes with less bandwidth and less computational cost are desirable for practical applications. Signature schemes with message recovery provide a feature that the message is recoverable from the signature and hence does not need to be transmitted separately for signature verification. Recently many signature schemes with message recovery have been designed in traditional as well as Identity based settings and most of the schemes are constructed using bilinear pairings over elliptic curves. Nevertheless, the computational cost of a pairing is more expensive and is higher than the scalar multiplication. Thus, signature schemes without pairing would be more appealing in terms of efficiency. In this paper, we propose an efficient identity-based message recovery scheme without pairings. In our scheme the message itself is not required to be transmitted together with the signature and so it turns out to have the least data size of communication cost. Also, we compare our scheme with the existing ID-based signature schemes with message recovery in terms of computational and communicational point of view. With the pairing-free realization, the proposed scheme is efficient and applicable for resource constrained devices.

A Novel Active/Passive Dual-Mode Sensing Technique for Detecting Vital Signs

Most conventional vital-sign sensing techniques are incompatible with the circuits in commercial wireless communication devices. In addition, conventional techniques cannot easily provide both active and passive sensing. This article presents a novel active/passive dual-mode sensing technique for detecting vital signs. The proposed technique simply combines the error vector magnitude (EVM) algorithm with the demodulation of wireless communication to detect vital signs. Therefore, any wireless device can be used as a vital-sign sensor without any modification of their circuits. The proposed technique can switch between active and passive modes as desired. The experimental results show that the developed sensing technique is very effective in detecting vital signs. In active mode, the maximum vital-sign detection distances of the developed 2.4-GHz sensor are 4.3 and 9 m with and without a 15-cm-thick reinforced concrete wall as a barrier, respectively. In passive mode, the developed sensor can penetrate a 15-cm-thick reinforced concrete wall to detect human vital signs within a range of 6.3 m.

ELEKTROMANYETİK ALAN MARUZİYETİNİN KAS DOKUSUNDA OLUŞTURDUĞU ETKİNİN MODELLENMESİ VE ANALİZİ

Bu çalışmada günlük hayatta maruziyetinden sakınılamayan farklı frekanslardaki cihazların oluşturduğu elektromanyetik yayılım için kas eşdeğer modelleri oluşturulmuştur. Günümüzde elektromanyetik alan yayan cihazların kullanımının giderek yaygınlaşması maruz kalınan frekans ve güç seviyelerinin çeşitliliğini artırmaktadır. Elektromanyetik dalgalar farklı güçlerde ve farklı frekanslarda, insan vücudunda değişik etkilerde bulunmaktadır. Bu etkiler vücutta dokuları ısıtmakta veya kimyasal yoldan değişimlere yol açmaktadır. Bu çalışmada, 900 MHz ve 1800 MHz frekanslarındaki cep telefonu, 2.45 GHz frekansındaki kablosuz haberleşme cihazlarının ve ayrıca 27.12 MHz frekansındaki tıbbi fizyoterapi tedavi cihazlarının (kısa dalga diatermi) insan kas dokusu üzerindeki etkilerini belirlemek amaçlı kas eşdeğer sıvıları oluşturulmuştur. Bu oluşturulan fantom model üzerinde elektromanyetik maruziyetin neden olduğu ısıl değişimler ölçülmüştür.

COMPREHENSIVE SURVEY OF WIRELESS COGNITIVE AND 5G NETWORKS

The tremendous progress in the wireless mobile communication devices and the continuous growth in the data rates and the usage with the entailment of enhanced performance in the network in the terms of the throughput, delay, energy utilization, data capacity, bandwidth utilization and the cost have led to the emergence of the 5G networks. The flexible transmission empowered by the cognitive radio networks make them prominent in the transmission of the applications that are significant and sensitive to latency. The paper surveys the details of the 5G network, the cognitive radio networks and the impacts in the network by having the cognitive radio in the 5G mobile wireless networks.

Active control of electromagnetically induced transparency based on terahertz hybrid metal-graphene metamaterials for slow light applications

Recently, the dynamically controlled electromagnetically induced transparency (EIT) metamaterials have been widely used in the slow light effect field to enhance the light-matter interactions and nonlinear effects, which has aroused the great attraction of many researchers. The emergence of two-dimensional materials has pushed this research to a new research hot again. Therefore, a terahertz hybrid metal-graphene metamaterial, consisting of a bi-layer metallic EIT metamaterial, an unpatterned monolayer graphene, and an encapsulated ion-gel layer, was proposed to actively control the EIT resonance. In this structure, the transparency peak of the bi-layer metallic EIT metamaterial can realize on-to-off switch through shifting the Fermi energy of graphene covering onto the dark mode resonators. Theoretical analysis and surface current distributions reveal that the active modulation can be attributed to the increasing damping rate of the dark mode caused by the actively controllable conductivity of the graphene. In addition, the active control of the group delay in the hybrid metamaterial is also demonstrated for the slow-light applications. Therefore, this work provides an alternative way to design compact slow-light devices for future terahertz wireless communications.