1,338 research outputs found

    CHATBOT APPLICATION AS SUPPORT TOOL FOR THE LEARNING PROCESS OF BASIC CONCEPTS OF TELECOMMUNICATIONS AND WIRELESS NETWORKS

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    There are several applications for Chatbots in education, as well as their contributions to mentoring in the learning process. Bots can assist teachers with staying up to date on new standards and evaluation methodologies. Bots can assist students in understanding tough subjects in a way that makes it appear as if they are being taught by another person. Chatbots serve as virtual assistants in the educational setting, improving efficiency or answering frequently asked questions. In this case, we work on the premise of investigating the potential of Chatbots as analytical tools for analyzing preferred types of learning material in a mobile learning environment, which leads to the acquisition of a proper level of knowledge on the topics of telecommunication and wireless networks

    Accurate quantum transport modelling and epitaxial structure design of high-speed and high-power In0.53Ga0.47As/AlAs double-barrier resonant tunnelling diodes for 300-GHz oscillator sources

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    Terahertz (THz) wave technology is envisioned as an appealing and conceivable solution in the context of several potential high-impact applications, including sixth generation (6G) and beyond consumer-oriented ultra-broadband multi-gigabit wireless data-links, as well as highresolution imaging, radar, and spectroscopy apparatuses employable in biomedicine, industrial processes, security/defence, and material science. Despite the technological challenges posed by the THz gap, recent scientific advancements suggest the practical viability of THz systems. However, the development of transmitters (Tx) and receivers (Rx) based on compact semiconductor devices operating at THz frequencies is urgently demanded to meet the performance requirements calling from emerging THz applications. Although several are the promising candidates, including high-speed III-V transistors and photo-diodes, resonant tunnelling diode (RTD) technology offers a compact and high performance option in many practical scenarios. However, the main weakness of the technology is currently represented by the low output power capability of RTD THz Tx, which is mainly caused by the underdeveloped and non-optimal device, as well as circuit, design implementation approaches. Indeed, indium phosphide (InP) RTD devices can nowadays deliver only up to around 1 mW of radio-frequency (RF) power at around 300 GHz. In the context of THz wireless data-links, this severely impacts the Tx performance, limiting communication distance and data transfer capabilities which, at the current time, are of the order of few tens of gigabit per second below around 1 m. However, recent research studies suggest that several milliwatt of output power are required to achieve bit-rate capabilities of several tens of gigabits per second and beyond, and to reach several metres of communication distance in common operating conditions. Currently, the shortterm target is set to 5−10 mW of output power at around 300 GHz carrier waves, which would allow bit-rates in excess of 100 Gb/s, as well as wireless communications well above 5 m distance, in first-stage short-range scenarios. In order to reach it, maximisation of the RTD highfrequency RF power capability is of utmost importance. Despite that, reliable epitaxial structure design approaches, as well as accurate physical-based numerical simulation tools, aimed at RF power maximisation in the 300 GHz-band are lacking at the current time. This work aims at proposing practical solutions to address the aforementioned issues. First, a physical-based simulation methodology was developed to accurately and reliably simulate the static current-voltage (IV ) characteristic of indium gallium arsenide/aluminium arsenide (In-GaAs/AlAs) double-barrier RTD devices. The approach relies on the non-equilibrium Green’s function (NEGF) formalism implemented in Silvaco Atlas technology computer-aided design (TCAD) simulation package, requires low computational budget, and allows to correctly model In0.53Ga0.47As/AlAs RTD devices, which are pseudomorphically-grown on lattice-matched to InP substrates, and are commonly employed in oscillators working at around 300 GHz. By selecting the appropriate physical models, and by retrieving the correct materials parameters, together with a suitable discretisation of the associated heterostructure spatial domain through finite-elements, it is shown, by comparing simulation data with experimental results, that the developed numerical approach can reliably compute several quantities of interest that characterise the DC IV curve negative differential resistance (NDR) region, including peak current, peak voltage, and voltage swing, all of which are key parameters in RTD oscillator design. The demonstrated simulation approach was then used to study the impact of epitaxial structure design parameters, including those characterising the double-barrier quantum well, as well as emitter and collector regions, on the electrical properties of the RTD device. In particular, a comprehensive simulation analysis was conducted, and the retrieved output trends discussed based on the heterostructure band diagram, transmission coefficient energy spectrum, charge distribution, and DC current-density voltage (JV) curve. General design guidelines aimed at enhancing the RTD device maximum RF power gain capability are then deduced and discussed. To validate the proposed epitaxial design approach, an In0.53Ga0.47As/AlAs double-barrier RTD epitaxial structure providing several milliwatt of RF power was designed by employing the developed simulation methodology, and experimentally-investigated through the microfabrication of RTD devices and subsequent high-frequency characterisation up to 110 GHz. The analysis, which included fabrication optimisation, reveals an expected RF power performance of up to around 5 mW and 10 mW at 300 GHz for 25 μm2 and 49 μm2-large RTD devices, respectively, which is up to five times higher compared to the current state-of-the-art. Finally, in order to prove the practical employability of the proposed RTDs in oscillator circuits realised employing low-cost photo-lithography, both coplanar waveguide and microstrip inductive stubs are designed through a full three-dimensional electromagnetic simulation analysis. In summary, this work makes and important contribution to the rapidly evolving field of THz RTD technology, and demonstrates the practical feasibility of 300-GHz high-power RTD devices realisation, which will underpin the future development of Tx systems capable of the power levels required in the forthcoming THz applications

    Evolution of High Throughput Satellite Systems: Vision, Requirements, and Key Technologies

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    High throughput satellites (HTS), with their digital payload technology, are expected to play a key role as enablers of the upcoming 6G networks. HTS are mainly designed to provide higher data rates and capacities. Fueled by technological advancements including beamforming, advanced modulation techniques, reconfigurable phased array technologies, and electronically steerable antennas, HTS have emerged as a fundamental component for future network generation. This paper offers a comprehensive state-of-the-art of HTS systems, with a focus on standardization, patents, channel multiple access techniques, routing, load balancing, and the role of software-defined networking (SDN). In addition, we provide a vision for next-satellite systems that we named as extremely-HTS (EHTS) toward autonomous satellites supported by the main requirements and key technologies expected for these systems. The EHTS system will be designed such that it maximizes spectrum reuse and data rates, and flexibly steers the capacity to satisfy user demand. We introduce a novel architecture for future regenerative payloads while summarizing the challenges imposed by this architecture

    Single-Frequency Network Terrestrial Broadcasting with 5GNR Numerology

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    L'abstract è presente nell'allegato / the abstract is in the attachmen

    Biased-Power Allocation and Shared-Antenna Selection Techniques for Spatial Modulation-Based Layer Division Multiplexing Systems

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    peer reviewedThis study proposes two approaches for improving the effectiveness of spatial modulation integrated into layer division multiplexing (SM-LDM) in broadcasting systems: biased-power allocation (Bi-PA) and shared antenna selection (SAS). Even though different data rates are employed in SM-LDM systems, Bi-PA enhances bit error rate (BER) fairness across layers. The ideal power ratios are adaptively determined by balancing signal-to-interference plus noise ratios with a preference for the lower layer (LL) that involves a higher modulation order. SAS alleviates the complexity of successive interference cancellation and enhances spectral and energy efficiencies. Both the LL and upper layer (UL) share the antenna selection decision and transmit using a single antenna. The UL carries a space shift keying signal while the entire power is allocated for the LL. We analyze the spectral efficiency for the SAS-based SM-LDM system with finite alphabet inputs. Numerical results demonstrate the advantages of the proposed approaches. Compared to pre-assigned-PA (Pre-PA), Bi-PA shows nearly identical BERs for both layers and solves the error floor problem. The sharing property and common layer transmission of SAS-based SM-LDM yield a significant BER reduction relative to conventional SM-LDM. It provides gains ranging from 7 to 15 dB for LL at BER equal to 10−3, while UL performance ranges from slight gain to minor loss. Furthermore, both Bi-PA and SAS techniques enhance the achievable LL rate and sum-rate at low and intermediate signal-to-noise ratio values. They can achieve an improvement of up to two bits in LL rate and less than one bit in sum-rate at a signal-to-noise ratio of −0.5 dB. These findings show that both proposed techniques have a considerable impact on enhancing the fairness, BER performance, and feasible rates of SM-LDM systems, making them promise for broadcast system designs

    Higher Instruction Human Resources Management (HRM) Hones and Information Administration Specialist Presence

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    nformation administration has an affect on human asset hones, agreeing to the organizational life cycle hypothesis. By comparing colleges that incorporate information administration in their scholastic educational programs to those that don't , we trust to decide the impact of information administration on the astuteness of Human Asset (HR) hones. Discoveries show that colleges that instruct information administration are way better prepared than those that don't development investigate, instruction, and data absorption through human asset hones. Besides, colleges that did not instruct information administration tend to be considerably more centered on operational issues and troubles in creating the aptitudes and information of their HR work force, and their execution is essentially lower. Research limitations and implications - collecting respondents through purposive sampling has its limitations. It is suggested to increase the number of respondents by broadening the study's geographical scope and extending its duration. Originality/importance - Numerous organizations and universities have conducted extensive research on human resource practices. However, courses in knowledge management that emphasize lecturers as knowledge management agents are still uncommon. This study also incorporates the life cycle theory by examining HR practices in higher education and encouraging institutions to prioritize strategic HR issues in their environment

    Energy-Aware Resource Optimization for Improved URLLC in Multi-hop Integrated Aerial Terrestrial Networks

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    The development of futuristic wireless infrastructure necessitates low power consumption, high relia- bility, and massive connectivity. One of the most promising solutions to address these requirements is the integration of aerial base station (ABS) based communication systems that employ both in the air (aerial) and on the ground (terrestrial) components. This integration enhances line of sight connections, enabling the fulfillment of escalating quality-of-service (QoS) demands. This article examines the problem of resource allocation in ABS assisted multi-hop wireless networks. We investigate a joint optimization problem that involves subcarrier (SC) assignment, power allocation, and blocklength allocation, subject to delay, reliability, and QoS constraints to improve the sum-rate under the finite blocklength (FBL) regime. We propose an approach for SC allocation and selection of cooperative ABSs based on matching theory. Subsequently, we employ an alternating optimization method to propose a novel bisection-based low-complexity adaptation (BLCA) algorithm to optimize the resource allocation policy. This algorithm includes a two-step projected gradient descent-based strategy to optimize the power allocation on each SC using dynamic and geometric programming. Furthermore, we examine flexible blocklength and power allocation use cases under the next generation of multiple access techniques. Monte-Carlo simulations validate that the proposed algorithmic solution significantly achieves a near-optimal solution while requiring 1600 times less computational cost compared to benchmarks in its counterparts

    Near-Real Time, Semi-Automated Threat Assessment of Information Environments

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    Threat assessment is a crucial process for monitoring and defending against potential threats in an organization’s information environment and business operations. Ensuring the security of information infrastructure requires effective information security practices. However, existing models and methodologies often fall short of addressing the dynamic and evolving nature of cyberattacks. Moreover, critical threat intelligence extracted from the threat agents lacks the ability to capture essential attributes such as motivation, opportunity, and capability (M, O, C). This contribution to knowledge clarification introduces a semi-automatic threat assessment model that can handle situational awareness data or live acquired data stream from networks, incorporating information security techniques, protocols, and real-time monitoring of specific network types. Additionally, it focuses on analysing and implementing network traffic within a specific real-time information environment. To develop the semi-automatic threat assessment model, the study identifies unique attributes of threat agents by analysing Packet Capture Application Programming Interface (PCAP) files and data stream collected between 2012 and 2019. The study utilizes both hypothetical and real-world examples of threat agents to evaluate the three key factors: motivation, opportunity, and capability. This evaluation serves as a basis for designing threat profiles, critical threat intelligence, and assessing the complexity of process. These aspects are currently overlooked in existing threat agent taxonomies, models, and methodologies. By addressing the limitations of traditional threat assessment approaches, this research contributes to advancing the field of cybersecurity. The proposed semi-automatic threat assessment model offers improved awareness and timely detection of threats, providing organizations with a more robust defence against evolving cyberattacks. This research enhances the understanding of threat agents’ attributes and assists in developing proactive strategies to mitigate the risks associated with cybersecurity in the modern information environment
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