Hasil untuk "Telecommunication"

Wonryeol Lee, Taeyong Jeong, Daju Lee et al.

This paper presents the design and performance evaluation of a fully integrated digital phased array-based nonlinear radar system. The proposed system employs a bi-static structure, where the transmitter and receiver are physically separated. The transmitter operates at 3–3.2 GHz, while the receiver is designed to capture the second harmonic responses at 6–6.4 GHz. The system consists of 64 channels for both transmission and reception, enabling electronic beam steering through phase shift control. To enhance the beamforming accuracy, a novel transmitter calibration method utilizing an oscilloscope instead of a network analyzer was implemented. The method simplifies synchronization requirements while maintaining precise phase alignment. Performance evaluation of the radar system was conducted through experimental validation in both free-space and concealed conditions, using arbitrary commercial electronic devices as targets. The experimental validation results demonstrated an average range error of 32.3 cm with a range resolution of 37.5 cm. Additionally, multi-target detection was performed using beamforming techniques. In free-space conditions, the radar achieved accurate target localization with angular errors below 1°. In concealed conditions, nonlinear reflections introduced minor localization errors due to clutter. Despite these challenges, the system successfully detected multiple targets by employing a clustering method. To the best of our knowledge, the system presented here is the first demonstration of a fully integrated digital phased array-based nonlinear radar in the open literature.

Hossein Mehri, Hani Mehrpouyan, Hao Chen

Traffic pattern prediction has emerged as a promising approach for efficiently managing and mitigating the impacts of event-driven bursty traffic in massive machine-type communication (mMTC) networks. However, achieving accurate predictions of bursty traffic remains a non-trivial task due to the inherent randomness of events, and these challenges intensify within live network environments. Consequently, there is a compelling imperative to design a lightweight and agile framework capable of assimilating continuously collected data from the network and accurately forecasting bursty traffic in mMTC networks. This paper addresses these challenges by presenting a machine learning-based framework tailored for forecasting bursty traffic in multi-channel slotted ALOHA networks. The proposed machine learning network comprises long-term short-term memory (LSTM) and a DenseNet with feed-forward neural network (FFNN) layers, where the residual connections enhance the training ability of the machine learning network in capturing complicated patterns. Furthermore, we develop a new low-complexity online prediction algorithm that updates the states of the LSTM network by leveraging frequently collected data from the mMTC network. Simulation results and complexity analysis demonstrate the superiority of our proposed algorithm in terms of both accuracy and complexity, making it well-suited for time-critical live scenarios. We evaluate the performance of the proposed framework in a network with a single base station and thousands of devices organized into groups with distinct traffic-generating characteristics. Comprehensive evaluations and simulations indicate that our proposed machine learning approach achieves a remarkable 52% higher accuracy in long-term predictions compared to traditional methods, without imposing additional processing load on the system.

Olusegun Timothy Odesola, Wilfred Olusoji Abila, Julianah Abosede Akinola

Disruptive times happen, and there is a chance of unpreparedness confronting the populace. However, it offers opportunities to adopt new methods or reinforce alternative processes in delivering value to customers. Remote work has always been practised globally, but the outbreak of the COVID-19 pandemic reinforced its practice. This study examined the connection between remote work management practices (RWMPs) and the operational performance of companies in the Nigerian telecommunication industry. The study’s population comprised the workers of the four (4) prominent telecommunication firms in Nigeria. The telecommunication firms in Nigeria at the point of time of this study were GLO, MTN, AIRTEL, and 9Mobile. A well-structured questionnaire was administered to 400 randomly selected respondents from a target population of 7,756, with 340 participants completing the survey, providing valuable primary data for this study. Descriptive statistical tools and structural equation modelling (SEM) were employed to analyze the data collected. Findings from the empirical study showed that RWMPs significantly and positively influence companies' operational performance in the Nigerian telecommunication industry. It was found that RWMPs substantially improve the operational performance of telecommunication companies in a developing economy like Nigeria. Consequently, it was recommended that the management of the companies in the Nigeria telecommunication industry provide more ICT facilities and other resources to sustain their RWMPs. To ensure that the operational performances of these firms will continue to improve at a geometrical rate management should not allow their staff to waste productive hours in their daily commute to work. The study was limited to telecommunication firms in Nigeria, therefore future studies could expand the scope to include other countries or regions, enabling a more comprehensive understanding of the phenomenon.

Siyuan Gao, Tianji Liu, Satoshi Iwamoto et al.

Magneto-optical (MO) interactions offer a direct route to nonreciprocal optical devices but are intrinsically weak in the optical domain, posing a major challenge in downsizing MO functional devices. In this study, we present a design strategy for ultra-thin MO Faraday rotators based on all-dielectric metasurfaces supporting high-quality factor quasi-bound states in the continuum (QBIC) modes. Light trapping in QBIC modes induced by band folding significantly enhances MO interactions in a controllable manner, enabling a technologically relevant 45$^\circ$ Faraday rotation with a MO metasurface that is only a few hundred nanometers thick. The design also incorporates electromagnetically induced transparency via spectrally overlapping resonant modes to achieve high light transmittance reaching 80%. This approach not only enables compact yet practical MO Faraday rotator but also holds promises for advancing free-space magnetic sensors and MO modulators.

Mitra Sofiyati, Fandi Azam Wiranata, Wervyan Shalannanda et al.

In Indonesia, many people with visual impairments are drawing public attention to their rights as fellow humans. One of the limitations that individuals with low vision face is their ability to recognize objects and navigate their surroundings due to difficulties in visual perception. In this modern era, deep learning technologies, especially in image classification, can help people with low vision overcome these challenges. In this paper, we discuss a deep learning system that optimizes image classification on users' smartphones to enhance visual support for individuals with low vision. We present an Android-based app, LoVi, designed to assist users with low vision. Powered by core systems within Sherpa models (TrotoarNet, IndoorNet, and CurrencyNet), LoVi has three modes: outdoor, indoor, and currency. The LoVi application provides over 80% accuracy for navigation on sidewalks, indoor object recognition, and currency identification. TrotoarNet aids in sidewalk navigation, IndoorNet assists with indoor object identification, and CurrencyNet recognizes Rupiah banknotes. Additionally, low-vision users can receive voice feedback for further accessibility.

何肖嵘, 廖江, 董斌 et al.

Mahmoud Youssuf , Mohamed Z. Abdelmageed

In addition to the benefits of hybrid phase shift keying (HPSK) modulation in reducing the peak to average power ratio of the transmitted signal to reduce the zero cross- ings and the 0◦-degree phase transmissions, HPSK enhances the bit error rate (BER) measure of the signal performance. The constellation of the HPSK is analyzed, and an expression for the conditional probability of HPSK modulation over additive white Gaussian noise (AWGN) is derived. This BER measure of HPSK is shown to outperform quadrature phase shift keying (QPSK) modulation. HPSK performance through Nakagami – m fading channel is also considered.

Shen Wang, Mahshid Delavar, Muhammad Ajmal Azad et al.

Caller ID spoofing is a global industry problem and often acts as a critical enabler for telephone fraud. To address this problem, the Federal Communications Commission (FCC) has mandated telecom providers in the US to implement STIR/SHAKEN, an industry-driven solution based on digital signatures. STIR/SHAKEN relies on a public key infrastructure (PKI) to manage digital certificates, but scaling up this PKI for the global telecom industry is extremely difficult, if not impossible. Furthermore, it only works with IP-based systems (e.g., SIP), leaving the traditional non-IP systems (e.g., SS7) unprotected. So far the alternatives to the STIR/SHAKEN have not been sufficiently studied. In this paper, we propose a PKI-free solution, called Caller ID Verification (CIV). CIV authenticates the caller ID based on a challenge-response process instead of digital signatures, hence requiring no PKI. It supports both IP and non-IP systems. Perhaps counter-intuitively, we show that number spoofing can be leveraged, in conjunction with Dual-Tone Multi-Frequency (DTMF), to efficiently implement the challenge-response process, i.e., using spoofing to fight against spoofing. We implement CIV for VoIP, cellular, and landline phones across heterogeneous networks (SS7/SIP) by only updating the software on the user's phone. This is the first caller ID authentication solution with working prototypes for all three types of telephone systems in the current telecom architecture. Finally, we show how the implementation of CIV can be optimized by integrating it into telecom clouds as a service, which users may subscribe to.

Emil Björnson, Yonina C. Eldar, Erik G. Larsson et al.

Wireless communication technology has progressed dramatically over the past 25 years, in terms of societal adoption as well as technical sophistication. In 1998, mobile phones were still in the process of becoming compact and affordable devices that could be widely utilized in both developed and developing countries. There were "only" 300 million mobile subscribers in the world [1]. Cellular networks were among the first privatized telecommunication markets, and competition turned the devices into fashion accessories with attractive designs that could be individualized. The service was circumscribed to telephony and text messaging, but it was groundbreaking in that, for the first time, telecommunication was between people rather than locations. Wireless networks have changed dramatically over the past few decades, enabling this revolution in service provisioning and making it possible to accommodate the ensuing dramatic growth in traffic. There are many contributing components, including new air interfaces for faster transmission, channel coding for enhanced reliability, improved source compression to remove redundancies, and leaner protocols to reduce overheads. Signal processing is at the core of these improvements, but nowhere has it played a bigger role than in the development of multiantenna communication. This article tells the story of how major signal processing advances have transformed the early multiantenna concepts into mainstream technology over the past 25 years. The story therefore begins somewhat arbitrarily in 1998. A broad account of the state-of-the-art signal processing techniques for wireless systems by 1998 can be found in [2], and its contrast with recent textbooks such as [3]-[5] reveals the dramatic leap forward that has taken place in the interim.

Arthur C. van Wijk, Christopher R. Doerr, B. Imran Akca

Arrayed waveguide gratings (AWGs) are key optical components of various new applications in telecommunication, astrology, medical imaging, and spectroscopy. It is a very powerful integrated light dispersion technology with significant flexibility for tailoring its performance to the individual system needs of each application. There are several examples of custom AWG designs in the literature aiming for improved system performance. In this review, we will provide an overview of the available methods for improving the bandwidth, spectral resolution, and transmission function shape of AWGs. The working principle as well as the advantages and disadvantages of each method will be discussed.

Zhaoming Zhang, Baixiao Chen, Minglei Yang et al.

Abstract Polarisation diversity radar enhances the performance of target detection. Time reversal exploits the multipath effect by adaptively matching propagation channels to improve the signal‐to‐noise ratio (SNR) and realise high detectability. This work combines polarisation diversity and time‐reversal technology to propose a time‐reversal detector suitable for a polarisation array radar. The maximum likelihood estimate is carried out for the time‐varying channel response to solve the channel mismatch problem, which may cause the degradation of time‐reversal performance. In addition, a conventional polarisation detector is developed under the same varying channel scenario to benchmark the time‐reversal detector, and furthermore, the SNR gain of the time‐reversal detector over the conventional detector is derived. Numerical simulations demonstrate the superiority of the time‐reversal detector. Both the polarisation detectors proposed can take advantage of the channel variations to improve the detectability, and the greater the energy brought by the channel changes, the better the detection performance achieved.

Eyal Buks

Fiber-based multi-wavelength lasers have a variety of important applications in telecommunication and meteorology. We experimentally study a fiber loop laser with an integrated Erbium doped fiber (EDF). The output optical spectrum is measured as a function of the EDF temperature. We find that below a critical temperature of about $10\unit{% K}$ the measured optical spectrum exhibits a sequence of narrow and unequally-spaced peaks. An intriguing connection between the peaks' wavelengths and the sequence of prime numbers is discussed. An hypothesis, which attributes the comb formation to intermode coupling, is explored.

Eugene A. Koreshin, Mikhail V. Rybin

We propose a design of interlaced wire medium with quasicrystalline lattice based on five-fold rotation symmetry Penrose tiling. The transport properties of this structure are studied. We distinguish two transport regimes, namely, propagation regime related to the low-frequency interval and localization regime in the high-frequency interval. While the former is observed in structures both with and without translation symmetry property, the latter is exclusive for aperiodic structures only. We show that the localization regime is promising for many applications including engineering of effective multi-channel devices for telecommunication and imaging systems.

Javeria Ambareen, M. Prabhakar, Tabassum Ara

Device-to-device (D2D) communications in 5G networks will provide greater coverage, as devices will be acting as users or relays without any intermediate nodes. However, this arrangement poses specific security issues, such as rogue relays, and is susceptible to various types of attacks (impersonation, eavesdropping, denial-of-service), due to the fact that communication occurs directly. It is also recommended to send fewer control messages, due to authenticity- and secrecyrelated prevailing requirements in such scenarios. Issues related to IoT applications need to be taken into consideration as well, as IoT networks are inherently resource-constrained and susceptible to various attacks. Therefore, novel signcryption algorithms which combine encryption with digital signatures are required to provide secure 5G IoT D2D communication scenarios in order to protect user information and their data against attacks, without simultaneously increasing communication costs. In this paper, we propose LEES, a secure authentication scheme using public key encryption for secure D2D communications in 5G IoT networks. This lightweight solution is a hybrid of elliptic curve ElGamal-Schnorr algorithms. The proposed scheme is characterized by low requirements concerning computation cost, storage and network bandwidth, and is immune to security threats, thus meeting confidentiality, authenticity, integrity and non-repudiation-related criteria that are so critical for digital signature schemes. It may be used in any 5G IoT architectures requiring enhanced D2D security and performance

Vanessa Klaas, Alberto Calatroni, Matea Pavic et al.

We present the setup of an observational study that aims to examine the application of wearables inambulatory palliative care to monitor the patients’ health status – especially during the transition phase fromhospital to home since this phase is critical and often patients are re-hospitalised. Following an user-centreddesign approach, we performed interviews with patients recruited at the Clinic of Radiation Oncology of theUniversity Hospital Zurich, Switzerland. The patient group was perceived as vulnerable and varied largelyin physiological burden and mental aspects. Special needs concern primarily obtrusiveness of the systemand sensitivity in the work with this patient group. With the deployment of the system, we gathered firstexperiences: the first patient was tracked over 12 weeks resulting in 84 tracked days, 181 digital questionnaireanswers, 40908 collected GPS points, 861 hours of heart rate measurements and positive feedback of thepatient.

Vicente Martin, Juan Pedro Brito, Carmen Escribano et al.

Quantum based technologies have been fundamental in our world. After producing the laser and the transistor, the devices that have shaped our modern information society, the possibilities enabled by the ability to create and manipulate individual quantum states opens the door to a second quantum revolution. In this paper we explore the possibilities that these new technologies bring to the Telecommu-nications industry

Luigi Calligaris, Andre Cascadan, Luis Eduardo Ardila-Perez et al.

This work presents the development of an Intelligent Platform Management Controller mezzanine in a Mini DIMM form factor for use in electronic boards compliant to the PICMG Advanced Telecommunication Computing Architecture (ATCA) standard. The module is based on an STMicroelectronics STM32H745 microcontroller running the OpenIPMC open-source software. The mezzanine has been successfully tested on a variety of ATCA boards being proposed for the upgrade of the experiments at the HL-LHC, with its design and firmware being distributed under open-source hardware license.

Bangwon Seo

We consider a hybrid combiner design for downlink massive multiple‐input multiple‐output systems when there is residual inter‐user interference and each user is equipped with a limited number of radio frequency (RF) chains (less than the number of receive antennas). We propose a hybrid combiner that minimizes the mean‐squared error (MSE) between the information symbols and the ones estimated with a constant amplitude constraint on the RF combiner. In the proposed scheme, an iterative alternating optimization method is utilized. At each iteration, one of the analog RF and digital baseband combining matrices is updated to minimize the MSE by fixing the other matrix without considering the constant amplitude constraint. Then, the other matrix is updated by changing the roles of the two matrices. Each element in the RF combining matrix is obtained from the phase component of the solution matrix of the optimization problem for the RF combining matrix. Simulation results show that the proposed scheme performs better than conventional matrix‐decomposition schemes.

Feng ZENG, Runhua WANG, Jia PENG et al.

The crowdsourcer who calls for sensing service can recruit enough mobile contributors quickly with the word of mouth mode,improving the quality of sensing tasks.The behavior of mobile contributors in mobile crowdsourcing with the WoM was investigated.It was supposed that each mobile contributor was rational,seeking for the highest utility.The behavior of mobile contributors with a two-level Stackelberg game was formulated.In the first-level game,a mobile contributor who directly worked for the crowdsourcer acted as the leader,while contributors invited by first-level contributors were followers called the second-level contributors.In the second-level game,the second-level contributors were the leaders and contributors invited by them were followers.The Nash equilibrium for each Stackelberg game was proved was existed and unique,and designed an algorithm to reach the equilibrium.Backward induction approach to compute the best response of each game was adopted,and the simulation results show the correctness of theoretical analysis for the interaction among contributors in crowdsoucing with WoM.

Yu CHEN, Xiaodong CHEN, Yue LIU

With the development of big data technology in recent years,various industries have strengthened their research and application in their professional field.For the wireless network planning specialty of mobile operators,it will effectively improve the accuracy and automation level of network planning by combining the market,network,terminal,base station,planning and other data sources owned by enterprises.For the existing large data planning platforms,there are generally problems that do not fully consider the discrimination of scenario or regional types,which have a certain impact on the planning results.Firstly,the data sources,processing application architecture and implementation method which the large data planning model of mobile wireless network needed were analyzed.Then,the standards,algorithms and parameter settings of the three coverage planning models of surface,line and point were studied after the key steps and model analysis of the big data planning in mobile wireless network.Finally,some ideas and suggestions were put forward for the construction and application of the big data planning model in mobile wireless network.