Hasil untuk "Cellular telephone services industry. Wireless telephone industry"

Wei Luo, Lefei He, Shanshan Xiao et al.

In this paper, the study focuses on metal frame smartphone antennas and presents the implementation of an eight-port broadband MIMO metal frame antenna array for smartphones. The MIMO antenna operates within a wide frequency band ranging from 3.23 to 6.45 GHz, covering the 5G New Radio (NR) band N78 (3.4–3.6 GHz), 5G China band N79 (4.8–5 GHz), and IEEE 802.11ac band (5.15–5.35 GHz and 5.725–5.85 GHz). The novelty of this work lies in the use of dumbbell-shaped defects within a Defected Ground Structure (DGS), which significantly enhances isolation between antenna elements. Each compact antenna element features a stepped radiator and stub, arranged orthogonally at the corners of the array. Through evolutionary design and optimal parameter analysis, we investigate the principles of antenna operation. The results exhibit that the measured isolation between any two antenna elements is superior to 15 dB and the measured reflection coefficients are below −10 dB. The measured overall radiation efficiency of the antenna exceeds 60%, and it is even higher than 75% within the frequency ranges of 3.4–3.6 GHz and 4.8–5 GHz, specifically. Several indicators, such as the envelope correlation coefficient (ECC), diversity gain (DG), total active reflection coefficient (TARC), and mean effective gain (MEG), confirm the antenna’s robust MIMO performance, with strong correlation between simulation and measurement.

Zhiwei Song, Hongxiang Miao, Xiaoming Xu et al.

A miniaturized enhanced isolation 8-unit MIMO antenna for smartphones is proposed in this paper. The units are planar inverted-F antennas with the same structure, and we use the slotting method and shorted probe to miniaturize them. The size of every unit is 14 × 6 mm2 (0.149 × 0.064λ2). We insert an L-shaped decoupling element into the middle of adjacent radiating elements and connect the decoupling element to the GND. Note that the decoupling elements are on the outer side of the substrate, and the radiating elements are on the inner side of the substrate. Finally, a prototype is fabricated and measured. The measured results show that the bandwidth of the MIMO antenna is from 3.0 GHz to 5.3 GHz (55.4%), which fully supports the n77, n78, and n79 in the 5G nR frequency band and the 4G LTE 42 frequency band (S11 less than −6 dB). The measured isolation of the MIMO antenna is greater than 25 dB by using the decoupling method in this paper. The envelope correlation coefficient of the proposed MIMO antenna is less than 0.08, its radiation efficiency is greater than 50%, and its gain is between 4.2 and 5.3 dBi in the whole operating frequency band.

Rajkishor Kumar, Avinash Chandra, Sreenath Reddy Thummaluru et al.

This paper presents a miniaturized planar dual-band short-ended metamaterial antenna with the backed ground plane to improve antenna bandwidths and radiation characteristics. The proposed dual-band metamaterial (MTM) antenna has been made up of the composite right- or left-handed transmission line (CRLH-TL) concept. Here, the backed ground plane has been employed to generate an extra coupling capacitance (CC), which shifts the ZOR frequency in the lower band while also improving ZOR matching and increasing the impedance bandwidth of the higher-order mode. In this proposed MTM antenna, interdigital capacitance (IDC) has been used in place of a simple series gap, which shifts the higher-order impedance bandwidth into a lower frequency band for second-band Wi-MAX applications (3.3–3.7 GHz). The proposed antenna offers a short-ended MTM, and hence the ZOR frequency is controlled by a series of LC lumped parameters. The proposed antenna offers dual-band behavior with measured −10 dB impedance bandwidths of 5.55% and 41.57% at centered frequencies of 2.70 GHz and 4.33 GHz, respectively. The overall electrical size of the designed antenna is 0.225λ0 × 0.144λ0 × 0.0144λ0 at ZOR (f0 = 2.70 GHz), where λ0 is the free space wavelength; therefore, it is applicable for different Wi-MAX application bands (2.5–2.7 GHz/3.3–3.8 GHz). Furthermore, the proposed dual-band MTM antenna provides compactness, low loss, stable gain, and radiation efficiency, and also offers omnidirectional radiation patterns in the E-plane and dipolar type radiation patterns in the H-plane, respectively.

Yuda Syahidin, K. P. Aksan Halim, R. Kurniawati et al.

The research objective was to apply unsupervised learning techniques by comparing several clustering methods in data mining to determine the best method for cell phone use cases in Indonesia. The data source comes from the Central Bureau of Statistics with the website url https://www.bps.go.id/. The data category used is the percentage of the population using cellular phones by province from 2012–2018 (34 records). The attributes used are the name of the province, the percentage (%) of the population using cellular telephones in urban areas and the percentage (%) of the population using cellular phones in rural areas. The unsupervised learning methods compared were k-medoids and k-means using the T - Test validity test based on the Davies Bouldin Index (DBI) to evaluate the cluster model. The analysis process uses Rapid Miner software. The mapping label is in the form of the cluster used, namely the high cluster (K1) for cellular phone use and the low cluster (K2) for cellular phone use. The best mapping result for the use of cell phones in urban areas is the k-medoids method with the T - Test result = 0.526 (DBI with $\mathbf{k}=2$) where 26 provinces $(\mathbf{K}1=\mathbf{cluster}_{-}1)$ and 8 provinces $(\mathbf{K}2\ =\mathbf{cluster}_{-}0)$ • Meanwhile, the best mapping result for the use of cellular phones in rural areas is the k-medoids method with the results of T - Test $=0.431$ (DBI with k $=2)$ where 31 provinces $(\mathbf{K}1=\mathbf{cluster}_{-}0)$ and 2 provinces (K2 $= \mathbf{cluster}_{-}1)$. Based on the mapping results, the mastery of cellular telephones in rural areas (2 %) and in urban areas (24 %) means that the understanding of the use of cellular telephones in Indonesia is very good. Overall, the k-medoid method is better at mapping cases of cell phone use in Indonesia. Based on the results, it is expected to be information for the government considering that Indonesia has the opportunity to grow very fast and large with the support of the government so that Indonesia's digital industry can overcome the lag behind other countries.

Jinfeng Yu, Lei Zhang, Zhi Wang

Iris localization is the most crucial part of the iris processing because its accuracy can directly affect the accuracy of biometric identification in subsequent steps. Yet, the quality of iris images may be sharply degraded due to interference from eyelashes and reflections during image acquisition, which can affect the localization accuracy adversely. To solve the problem, an iris localization algorithm based on effective area is proposed. First, YOLOv4 is used to crop the image to obtain the effective iris area, which is beneficial in improving the accuracy of subsequent localization. Furthermore, a method to remove reflective noise is proposed, which can effectively avoid the problem of noise interference in the process of inner boundary determination. Finally, aiming at the edge deviation caused by eyelashes, an outer boundary adjustment method is proposed. The experimental results show that the proposed method achieves good performance in the localization of iris images of both good quality and noise interference and outperforms other state-of-the-art methods.

R. Mbarek, Yasser Baeshen

Nowadays the telecommunications sector is becoming very complex Because of the panoply of high-speed technological services. Customers are abandoning the services offered by telecommunications operators because of their dissatisfaction with the services they offer. «Churn» or the migration of customers from one telecommunications operator to another is the main problem facing the telecommunications industries worldwide. Business managers consider the quality of service to be paramount. As a consequence, they have devised reliable criteria to assess the flow of customers within the market and check and evaluate whether customers are satisfied with the services they are offered. This, in turn, helps to establish customer loyalty and provide a healthy and sustainable trading agreement. Service quality control assessment is pivotal to identify the leverage and evaluate the internal and external competition in the industry. Although this concept is not foreign, rather it is an essential business management tool. The goal of this study is to determine the significant criteria for the cause migration of a Tunisie Telecom customer to another operator. Telecommunication is an essential lifelong component that contributes to the comfortability of our daily lives. The various means of telephone communication play a significant role in improving the effectiveness of communication industry. Every telecommunication operator is aware today that it is cheaper to retain an existing customer than to seek to recruit a new one. Indeed, we noticed that the telecommunications market is characterized by intense competition, where a change in the quality of service or a negative interaction perceived by the customer could risk losing them. As a result, the majority of operators introduce studies and action plans to retain customers and keep them as long as possible. The notion of keeping customers and building loyalty is probably one of the biggest challenges that operators around the world face in global competition. In order to achieve the goals set by telecom operators and to achieve maximum profitability, operators must effectively analyze market data and adopt a most effective targeted communications strategy for their customers. Keywords: churn analysis, customer loyalty, mobile marketing, telecommunications, telecommunications customer.

Hyukjun Lee, Wonjae Ryu, Wonjin Sung et al.

5G new radio (NR) provides enhanced transmission capabilities to transceivers by utilizing the massive multiple-input multiple-output (MIMO) technology with a significantly increased number of antenna elements. Such transmission requires massive arrays to perform accurate high-gain beamforming over the millimeter-wave frequency band. There is no fixed form of array structures for 5G NR base stations, but they are likely to include multiple subarrays or panels for practicality of implementation and are expected to cover the user equipment (UE) in various locations. In this paper, we propose an array structure to transmit signals over the three-dimensional (3D) space in an isotropic fashion for all types of UEs in ground, aerial, and high-rise building locations, by employing panels on surfaces of a polyhedron. We further derive exact beamforming equations for the proposed array and show the resulting beams provide improved receiver performance over the exiting conventional beamforming. The presented beamforming expressions can be applied to an arbitrary multipanel array with massive antenna elements.

Zakaria Mahlaoui, Eva Antonino-Daviu, Adnane Latif et al.

A frequency reconfigurable patch antenna design based on the characteristic mode analysis is presented. The antenna presents a reconfigurable lower band and a steady band at higher frequencies. A slot is etched on the ground plane of the antenna, where two varactor diodes are placed on each side of the slot in order to tune the lower band. The first resonant frequency shifts down by varying the reverse voltage of the varactor, whereas the second operating frequency keeps stable. The proposed antenna is designed to cover WLAN bands, offering a first band operating at 2 GHz and a second band ranging from 5.3 GHz to 5.8 GHz. A prototype has been fabricated and measurements are provided, which validate the proposed analysis, method, and design procedure.

Danvir Mandal, S. S. Pattnaik

A novel wide coplanar waveguide- (CPW-) fed multiband wearable monopole antenna is presented. The multiband operation is achieved by generating slanted monopoles of different lengths from an isosceles triangular patch. The different operating frequencies of the proposed antenna are associated with the lengths of the slanted monopoles, which are determined under quarter wavelength resonance condition. The CPW line is used as a multiband impedance-matching structure. The two grounds are slightly extended for better impedance matching. The proposed antenna is designed to cover the 1800 MHz GSM, 2.4 GHz/5.2 GHz WLAN, and 3.5 GHz WiMAX bands. The measured peak gains and impedance bandwidths are about 4.18/3.83/2.6/2.94 dBi and 410/260/170/520 MHz for the 1550-1960 MHz/2.3-2.56 GHz/3.4-3.57 GHz/5.0-5.52 GHz bands, respectively. The calculated averaged specific absorption rate (SAR) values at all the resonant frequencies are well below the standard limit of 2 W/kg, which ensures its feasibility for wearable applications. The antenna performance under different bending configurations is investigated and the results are presented. The reflection coefficient characteristics of the proposed antenna is also measured for different on-arm conditions and the results are compared. A good agreement between experimental and simulation results validates the proposed design approach.

Elisa Giusti, Piotr Samczynski, Maria-Pilar Jarabo-Amores et al.

M. Shaheen, R. Lodhi, Z. Mahmood et al.

Dong-Wook Seo, Jae-Ho Lee, Hyungsoo Lee

We propose the integration of the resonant coil for wireless power transfer (WPT) and the implantable antenna for physiological signal transfer. The integration allows for a compact biomedical implantable system such as electrocardiogram (ECG) recorder and pacemaker. While the resonant coils resonate at the frequency of 13.56 MHz for the WPT, the implantable antenna works in the medical implant communications service (MICS) band of 402–405 MHz for wireless communications. They share the narrow substrate area of a bar-type shape; the coil has the current path on the outer part of the substrate and the meandered planar inverted-F antenna (PIFA) occupies the inside of the coil. To verify the potentials of the proposed structure, a prototype is fabricated and tested in vitro. The power transfer efficiency (PTE) of about 20% is obtained at a distance of 15 mm and the antenna gain of roughly −40 dBi is achieved.

Son Xuat Ta, Ikmo Park

This paper presents dual-band operation of a single-feed composite cavity-backed four-arm curl antenna. Dual-band operation is achieved with the presence of the asymmetrical arm structure. A pair of vacant-quarter printed rings is used in the feed structure to produce a good circular polarization (CP) at both bands. The cavity-backed reflector is employed to improve the CP radiation characteristics in terms of the 3-dB axial ratio beamwidth and broadside gain. The proposed antenna is widely applicable in dual-band communication systems that have a small frequency ratio. Examples of such a system are global positioning systems.

Junhao Xie, Wei Zhou, Gongjian Zhou et al.

Real-time tracking of maneuvering targets is the prerequisite for continuous imaging of moving targets in inverse synthetic aperture radar (ISAR). In this paper, the range and azimuth tracking (RAT) method with wideband radar echoes is first presented for a mechanical scanning monopulse ISAR, which is regarded as the simplest phased array unit due to the two antenna feeds. To relieve the estimation fluctuation and poor robustness of the RAT method with a single snapshot, a modified range and azimuth tracking approach based on centroid algorithm (RATCA) with forgotten factor and multiple echoes is then proposed. The performances of different forgotten factors are investigated. Both theoretical analysis and experimental results demonstrate that RATCA is superior to RAT method. Particularly, when target echo is missing occasionally, RAT method fails while RATCA still keeps good performance. The potential of continuous imaging with shipborne ISAR is verified by experimental results. With minor modification, the method proposed in this paper can be potentially applied in the phased array radar.

Abdelhamid Bou-El-Harmel, Ali Benbassou, Jamal Belkadid

Several antenna designs have been made in order to obtain a novel electrically small 3D UHF spherical antenna (ka = 0.1916), which has a resonance frequency close to 915 MHz, produces a quasi-isotropic radiation with an opening angle equal to 360° in the whole space, and is used for RFID, WSN, and RSN applications. These antennas are based on different shapes and are wrapped on the Styrofoam sphere surface of dielectric constant close to air (ɛr=1.06). A T-match configuration is used to adapt the input impedance of antennas to a value of 50 Ω. The antennas form allows for placing the sensor electronics in its interior, to reconfigure it for numerous values of impedances and to operate it in other ISM bands by adjusting their geometric parameters.

T. Beard, Jeffrey T. Macher, J. Mayo

M. Abdel-Rahman, M. Kamran Saleem, Najeeb Al-Khalli et al.

We report on the fabrication and characterization of a novel antenna-coupled detector configuration for detection at 94 GHz, a coplanar waveguide- (CPW-) fed, slot-excited twin dielectric resonator antenna- (DRA-) coupled niobium (Nb) microbolometer. The antenna is based on two low permittivity cylindrical dielectric resonators (CDRs) excited by rectangular slots placed below the CDRs. The antenna resonant currents are fed to an Nb microbolometer by the means of a CPW feed. The ceramic DRA structure is manufactured using a novel fabrication process that enables patterning an SU-8–Alumina (Al2O3) nanopowder composite using conventional photolithography. The detector measured a voltage responsivity of 0.181 V/W at a modulation frequency of 150 Hz. The detector measured a time constant of 1.94 μs. The antenna radiation pattern of the developed detector configuration was measured and shows a good agreement with the simulation.

V. Khare, S. Garg, Sapna Shukla et al.

Chufeng Hu, Nanjing Li

The morphology of vegetation greatly impacts propagation of polarized electromagnetic wave. In order to validate this phenomenon, the mathematical relation between the differential propagation constant of forest vegetation and of its polarized echo is quantitatively derived by using backscattering power profile. The fluctuation of differential propagation constant with frequency is analyzed by combining the morphological characteristics of vegetation. The accurate copolarized data of 3–10 GHz frequency-domain of small trees are obtained by indoor wideband polarimetric measurement system. The results show that morphological characteristics of vegetation at different frequencies can be obtained by the differential propagation constant of polarized electromagnetic wave. At low frequencies, the plants with structural features presented oriented distribution. However, the plants show random distribution of the echoes at higher frequencies, which is mainly from the canopy. The research provides important information to choose the coherence models employed in the parameters retrieval of vegetations.

Jorge Antonio Silva Ceneno, Regina Tiemy Kishi, Edson Aparecido Mitishita

Cet article présente une méthode d’identification des toits pour la récupération des eaux pluviales, basée sur l’utilisation des données d’un laser à balayage et d’imagerie visible et proche infrarouge. La discrimination automatique des surfaces couvertes de végétation et de toits s’avère difficile lorsque seule la hauteur des pixels est utilisée ; la procédure s’améliore lorsque la variation locale de l’altitude, c’est-à-dire la texture, est analysée. L’image obtenue par balayage laser est d’abord seuillée en fonction de la hauteur. La morphologie mathématique est également utilisée pour sélectionner les plus grandes surfaces, plus propices à la récupération des eaux pluviales. Lorsque la densité du nuage de points est trop faible, l’analyse conjointe des données laser et des photographies aériennes permet une meilleure discrimination de la végétation et des toits. L'étude démontre la viabilité d’une utilisation conjointe du laser à balayage et de la photographie aérienne pour une telle application et la puissance de l’analyse texturale pour la discrimination.