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

William . Gillette, Phyllis F. Field

The communication sector of an economy comprises a range of technologies, physical media, and institutions/rules that facilitate the storage of information through means other than a society's oral tradition and its transmission over distances beyond the normal reach of human conversation. This chapter provides data on the historical evolution of a disparate range of industries and institutions contributing to the movement and storage of information in the United States over the past two centuries. These include the U.S. postal service, the newspaper industry, book publishing, the telegraph, wired and cellular telephone service, radio and television, and the Internet.

J. Curran, M. Meuter

H. Bertoni

Khurshid Alam, Mohammad Asif Habibi, Matthias Tammen et al.

Open-radio access network (O-RAN) seeks to establish the principles of openness, programmability, automation, intelligence, and hardware-software disaggregation with interoperable and standard-compliant interfaces. It advocates for multi-vendorism and multi-stakeholderism within a cloudified and virtualized wireless infrastructure, aimed at enhancing the deployment, operation, and management of RAN architecture. These enhancements promise increased flexibility, performance optimization, service innovation, energy efficiency, and cost effectiveness across fifth-generation (5G), sixth-generation (6G), and beyond networks. A silent feature of O-RAN architecture is its support for network slicing, which entails interaction with other domains of the cellular network, notably the transport network (TN) and the core network (CN), to realize end-to-end (E2E) network slicing. The study of this feature requires exploring the stances and contributions of diverse standards development organizations (SDOs). In this context, we note that despite the ongoing industrial deployments and standardization efforts, the research and standardization communities have yet to comprehensively address network slicing in O-RAN. To address this gap, this paper provides a comprehensive exploration of network slicing in O-RAN through an in-depth review of specification documents from O-RAN Alliance and research papers from leading industry and academic institutions. The paper commences with an overview of the relevant standardization and open source contributions, subsequently delving into the latest O-RAN architecture with an emphasis on its slicing aspects. Furthermore, the paper explores O-RAN deployment scenarios, examining options for the deployment and orchestration of RAN and TN slice subnets. It also discusses the slicing of the underlying infrastructure and provides an overview of various use cases related to O-RAN slicing. Finally, it summarizes the potential research challenges identified throughout the study.

Yiming Guo, Dongyan Ding, Fengtong Mei et al.

Recently, symmetric sparse uniform linear arrays (SSULAs) have been widely used for mixed far-field (FF) and near-field (NF) source localization owing to their high degrees of freedom and large array aperture. However, the heavy levels of mutual coupling of SSULAs limit the accuracy of source localization. In this article, a novel sparse array structure called symmetric super transformed nested array (SSTNA) is designed for mixed source localization, which combines the advantages of high degrees of freedom and the ability to tolerate strong mutual coupling. The SSTNA can be generated by two steps. First, we switch the position of the two subarrays within the nested array and relocate the sensors of dense subarray. Secondly, the whole array is flipped utilizing the zeros as symmetry point. We provide an analytical expression for the proposed array and derive expressions of its degrees of freedom and weight functions. Numerical results demonstrate that SSTNA is superior to existing sparse arrays in both direction of arrival (DOA) and distance estimation.

Emmanuel Issifu Fuseini, Muazu Ibrahim, Ibrahim Osman Adam et al.

Abstract Studies on the tripartite nexuses among information and communication technology (ICT), financial development (FD), and banking sector efficiency have largely produced mixed findings. More importantly, how countries’ levels of ICT advancement moderate FD-banks efficiency interlinkages need to be re-assessed. By utilizing data from 48 African countries covering 2004 to 2021 in assessing the tripartite interlinkages, the empirical findings based on the system Generalized Method of Moments (GMM) show that ICT goods imports significantly impact the banking sector positively in enhancing financial access to allocate finance efficiently: Individuals using the internet enhances the banking sector’s efficiency. Fixed telephone subscriptions, Mobile cellular subscriptions, and secured internet servers impact banking sector efficiency insignificantly. Financial formalization and informalization significantly impact banking sector efficiency positively, except in the case of ICT goods imports being added to the equation. On the moderating role of the ICT proxies, our finding showed that how ICT moderates the impact of FD on banking sector efficiency is conditioned on both the proxy of ICT and FD. Further findings show an inverted U-shaped relationship between individuals using the internet, ICT goods imports, and the banking sector efficiency nexus. The study discusses the implications for policy and makes key recommendations to improve ICT infrastructure and FD. Impact statement The role of financial development in banking sector efficiency cannot be overemphasized. At the same time, how information and communication technology (ICT) mediate the link between financial development and banking sector efficiency is gaining traction. This study therefore examines these tripartite relationships. Based on the findings, it is uncovered that the integration of ICT into the banking industry can provide efficiency gains that are not directly related to financial sector formalization or informalization.

Yueh-shian Lee

Abstract With the increasing development of digital technology, people receive information comes from digital information. The methods of develop financial service marketing consist of internet, telephone, and physical bank branches in financial and insurance industry. In particular, the Covid-19 pandemic has led the benefits of digital marketing in the financial and insurance industry have grown significantly. The sales and services of insurance products focus on human being and needs to contact customers for a long time in financial service industry. The corporate brand image is a representative of the perception to customers and an important cornerstone for building corporate competitiveness. Digital marketing is one of the important tools for building corporate image. The purpose of this research is to analyze the relationship among digital marketing, brand emotional attachment, and brand attitudes of insurance companies. Structural equation modeling (SEM) was used to conduct empirical analysis to provide relevant information for insurance practitioners to improve competitiveness. This study found that digital marketing has a positive and significant impact on brand emotional attachment; digital marketing has a positive and significant impact on brand attitude; brand emotional attachment has a positive and significant impact on brand attitude; and digital marketing through the intermediary effect of brand emotional attachment has a significant positive impact on brand attitude. Therefore, insurance operators must strengthen the establishment of good use of digital media to establish customers' attitudes towards the brand. JEL classification numbers: M31. Keywords: Digital Marketing, Brand Emotional Attachment, Brand Attitude.

Heeje Han, Hongjoon Kim

A flat phase difference across a broad bandwidth is achieved by appropriately combining the positive and negative phase propagation of right-handed (RH) and left-handed (LH) transmission lines (TLs), respectively. Employment of lumped elements provides easy realization of both TLs with the desired frequency passband, characteristic impedance, and phase propagation. The proposed quadrature power divider (QPD) was fabricated in a compact size by only using lumped elements instead of general TLs with a large area and a narrow bandwidth. The fabricated QPD maintains a flat phase difference of 90° ± 8.7° over a frequency range of 1.19–2.96 GHz while its circuit size is 0.036 λg2. Owing to drastic size reduction of the QPD, the proposed balanced amplifier (BA) also could be realized with an extremely compact size of 0.044 λg2 and broad bandwidth unlike in other BAs reported in the literature and maintains a return loss of less than −10 dB at each port over the bandwidth of the QPD.

S. Khan, Usman Naseem, Haris Siraj et al.

Next‐generation wireless communication networks, in particular, the densified 5G will bring many developments to the existing telecommunications industry. The key benefits will be the higher throughput and very low latency. In this context, the usage of unmanned aerial vehicle (UAV) is becoming a feasible option for deploying 5G services on demand. At the same time, the immense bandwidth potential of mmWave has strengthened its performance in radio communication. In this article, we provide a consolidated synthesis on the role of UAVs and mmWave in 5G, emphasis on recent developments and challenges. The review focuses on UAV relay architectures, identifies the relevant problems and limitations in the deployment of UAVs using mmWave in both access and backhaul links simultaneously. There is a critical analysis of the optimum placement of the UAVs as a relay with a focus on the mmWave band. The distinctive rich characteristics of the mmWave propagation and scattering are presented. We also synthesis mmWave path loss models. Then, the scope of artificial intelligence and machine learning techniques as an efficient solution for combating the dynamic and complex nature of UAV‐based cellular communication networks are discussed. In the end, security and privacy issues in UAV‐based cellular network are spotlighted. It is believed that the literature discussed, and the findings reached in this article are of significant importance to researchers, application engineers and decision‐makers in the designing and deployment of UAV‐supported 5G network.

Emil J. Khatib, R. Barco

Industry 4.0 is generalizing the use of wireless connectivity in manufacturing and logistics. Specifically, in Smart Logistics, novel Industry 4.0 technologies are used to enable agile supply chains, with reduced management, energy and storage costs. Cellular networks allow connectivity throughout all the scenarios where logistics processes take place, each having their own challenges. This paper explores such scenarios and challenges, and proposes 5G technology as a global unified connectivity solution. Moreover, this paper proposes a system for exploiting the application-specific optimization capabilities of 5G networks to better cater for the needs of Smart Logistics. An application traffic modeling process is proposed, along with a proactive approach to network optimization that can improve the Quality of Service and reduce connectivity costs.

Zhao Long Wang, Chuang Ming Tong, Tong Wang et al.

This paper proposed a new radar echo simulation method for ultra-low altitude targets in far-field conditions. Based on the electromagnetic (EM) scattering calculation of target and environment, combined with the weighted four-path model, the scattering data of target, environment, and multipath are obtained. The Range-Doppler ring partitioning method is used to determine the size of the minimum resolution units, and then the environment is divided into several scattering elements. By using the method of temporal decomposition, the wide-time pulse is decomposed into a plurality of narrow pulse signals, and the narrow pulses act on scattering elements with different distances and orientations in space. The total echo is obtained by a linear superposition of the responses of each scattering unit. In addition, the numerical results with different parameters, including signal bandwidths, target types, and target height, are simulated and analysed. The simulation results demonstrate that the proposed method can provide a better description of the scattering characteristics of sea-skimming targets in complex scenes in far-field conditions. Meanwhile, it can be applied to the detection and recognition of ultra-low altitude targets above the sea surface.

Natasha Antoinette Hall, Johann Wilhelm Odendaal, Johan Joubert

A wideband feed network for a Vivaldi antenna array is presented. A limitation of current wideband antenna arrays is the bandwidth of either the feed network or the antenna element. The proposed antenna array consists of four wideband Vivaldi antennas fed with an improved wideband feed network to extend the useable bandwidth of the array. The proposed feed network consists of coplanar waveguide-to-slotline-to-microstrip line transitions. The feed network has a single coplanar waveguide input and four microstrip line output ports. The feed network achieved uniform amplitude and phase balance and an impedance bandwidth of 160% from 1 GHz to 9 GHz. The feed network was used in a uniform linear antenna array to feed four Vivaldi antenna elements. The Vivaldi antenna array achieved stable radiation patterns from 1.3 GHz to 8 GHz, resulting in a useable bandwidth of 144%. The antenna array has a minimum gain of 8 dBi and a maximum of 13.8 dBi within the frequency band. Results for a prototype Vivaldi antenna array, measured in a compact antenna test range, are presented and compared to simulated results from CST Studio Suite.

Pillalamarri Laxman, Anuj Jain

Stealth wearable wireless devices are gaining much attention in the personal security and fashion designing industry. A multiple-input multiple-output wideband circularly polarized antenna wearable on a dress (textile-related), which is immune to bending, is described in this paper, where a wearable on fabric dress application uses the MIMO techniques. It consists of two multiple-input multiple-output types of antenna elements: the resonating elements are created resembling a beautiful peacock shape and the ground plane is appropriately designed. A voltage is applied to each antenna element; the ground plane contains a microstrip transmission line-fed and a rectangular upside-down L-shaped (vertically flipped) strip used for circular polarizing. The antenna covers a 3 dB axial-ratio-band-width (ARBW) value of 5.20–7.10 GHz and impedance bandwidth (S11 less than −10 dB) of 03.60–13.0 GHz. The proposed attachable wearable fabric (textile) multiple-input multiple-output wideband antenna exhibits envelope correlation coefficient (ECC) <0.02, diversity gain (DG) >9.96, channel capacity loss (CCL) <0.2 b/s/Hz, total active reflective coefficient (TARC) <−10 dB, mean effective gain (MEG) ratio within ±0.5 dB. There is dual-sense circular polarization in this antenna and high isolation between resonating elements (higher than 18). A specific absorption rate (SAR) of the proposed antenna for human tissues specimen is also discussed for different situations related to the human body. The overall size of the proposed CP textile MIMO antenna is 34 : 5 × 42 × 1 mm3. Because of its clothing layers (textile), practical performance, and miniature size, the designed MIMO antenna may be helpful for wearable on cloths on human body wireless devices and systems. The proposed antenna can be made unrecognizable because of the beautiful peacock design that can easily mix with the designs of fabric (in the fashion dress). The simulated antenna was fabricated with the help of conventional manual fabrication techniques and tested in real-time situations. The edge-to-edge distance amid the MIMO radiating antennas is 14.2 mm, and the achieved isolation is greater than 18 dB after optimization of the proposed antenna.

Yifei Wei, Zhaoying Wang, Da Guo et al.

To reduce the transmission latency and mitigate the backhaul burden of the centralized cloud-based network services, the mobile edge computing (MEC) has been drawing increased attention from both industry and academia recently. This paper focuses on mobile users’ computation offloading problem in wireless cellular networks with mobile edge computing for the purpose of optimizing the computation offloading decision making policy. Since wireless network states and computing requests have stochastic properties and the environment’s dynamics are unknown, we use the model-free reinforcement learning (RL) framework to formulate and tackle the computation offloading problem. Each mobile user learns through interactions with the environment and the estimate of its performance in the form of value function, then it chooses the overhead-aware optimal computation offloading action (local computing or edge computing) based on its state. The state spaces are high-dimensional in our work and value function is unrealistic to estimate. Consequently, we use deep reinforcement learning algorithm, which combines RL method Q-learning with the deep neural network (DNN) to approximate the value functions for complicated control applications, and the optimal policy will be obtained when the value function reaches convergence. Simulation results showed that the effectiveness of the proposed method in comparison with baseline methods in terms of total overheads of all mobile users.

Lei Liang, Jie Sun, Hailin Li et al.

An efficient pattern synthesis approach is proposed for the synthesis of a time-modulated sparse linear array (TMSLA) in this paper. Due to the introduction of time modulation, the low/ultralow side lobe level can be obtained with a low amplitude dynamic range ratio. Besides, it helps reduce the difficulty of antenna feeding system effectively. Based on particle swarm optimization (PSO) and convex (CVX) optimization, this paper proposes a hybrid optimization method to suppress the grating lobes of the sparse arrays, peak side lobe level (PSLL), and peak sideband level (PSBL). Firstly, the paper utilizes the CVX optimization as a local optimization algorithm to optimize the elements’ switch-on duration time, which reduces the side lobe of the array. Secondly, with the PSBL as the objective function, the paper adopts the PSO as a global optimization algorithm to optimize the elements’ positions and switch-on time instant, which helps reduce the loss of sideband power caused by time modulation. With respect to the time modulation model, variable aperture sizes (VAS) and more flexible pulse-shifting (PS) schemes are used in this paper. Owing to the introduction of time modulation and CVX optimization, the proposed method is much more feasible and efficient than conventional approaches. Furthermore, it has better array pattern synthesis performance. Numerical examples of the TMSLA and comparisons with the reference are presented to demonstrate the effectiveness of the proposed method.

Jianhua Xu, Yongjiu Zhao, Qian Xu

A Weibull distribution has been proposed for the probability density function (PDF) of the magnitude of the E-field in a reverberation chamber (RC). However, the Weibull distribution has two parameters, and if the parameters are position sensitive, the use of the Weibull distribution could be very limited. We investigate the sensitivity of the estimated parameters of the Weibull distribution in this study; the measurement results show that the parameters of the Weibull distribution depend on the positions of the antenna (or device under test), but not sensitive, and the statistical behavior of the parameters can be quantified. This means that the model of the Weibull distribution has a wider usable frequency range than that of the Rayleigh distribution and the statistical variation of the parameters needs to be considered.

I-Fong Chen, Chia-Mei Peng, Jing-Jing Bao et al.

A 2 × 2 MIMO antenna for metal-housing mobile handset application is proposed in this article. The polarization diversity is used to arrange the two antennas’ setup. The asymmetric U-shaped nonuniform slot antenna provides two different resonant bands are designed to be operated in long term evolution (LTE) covers lower band (698 MHz to 960 MHz) and upper band (1710 MHz to 2700 MHz). The modified type III balun is used for upper-operating band, and the open stub is used for lower-operating band, good impedance bandwidth, and radiated pattern and efficiency are shown. The isolation (S21) between the antennas is more than 20 dB, and the envelope correlation coefficient (ECC) is less than 0.02. A prototype of the proposed antenna chiselling in the metal-housing mobile handset (with 160 mm in length, 10 mm in height, and 70 mm in width) is fabricated and experimentally studied.

Anton Tijhuis, Ann Franchois, Jean-Michel Geffrin

An approach is presented to combine the response of a two-dimensionally inhomogeneous dielectric object in a homogeneous environment with that of an empty inhomogeneous environment. This allows an efficient computation of the scattering behavior of the dielectric cylinder with the aid of the CGFFT method and a dedicated extrapolation procedure. Since a circular observation contour is adopted, an angular spectral representation can be employed for the embedding. Implementation details are discussed for the case of a closed 434 MHz microwave scanner, and the accuracy and efficiency of all steps in the numerical procedure are investigated. Guidelines are proposed for choosing computational parameters such as truncation limits and tolerances. We show that the embedding approach does not increase the CPU time with respect to the forward problem solution in a homogeneous environment, if only the fields on the observation contour are computed, and that it leads to a relatively small increase when the fields on the mesh are computed as well.

Bo Kong, Yuhao Wang, Henry Leung et al.

In an integrated radar-communication network, multiuser access techniques with minimal performance degradation and without range-Doppler ambiguities are required, especially in a dense user environment. In this paper, a multiuser access scheme with random subcarrier allocation mechanism is proposed for orthogonal frequency division multiplexing (OFDM) based integrated radar-communication networks. The expression of modulation Symbol-Domain method combined with sparse representation (SR) for range-Doppler estimation is introduced and a parallel reconstruction algorithm is employed. The radar target detection performance is improved with less spectrum occupation. Additionally, a Doppler frequency detector is exploited to decrease the computational complexity. Numerical simulations show that the proposed method outperforms the traditional modulation Symbol-Domain method under ideal and realistic nonideal scenarios.

Nancie Gunson, Diarmid Marshall, H. Morton et al.