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2189 research outputs found
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ACO-Inspired Energy-Aware Routing Algorithm for Wireless Sensor Networks, Journal of Telecommunications and Information Technology, 2019, nr 1
Full text linkMulti-hop networks, such as WSNs, become an object of increasing attention as an emerging technology which plays an important role for practical IoT applications. These multi-hop networks generally consist of mobile and small terminals with limited resources, which makes them vulnerable to various network status changes. Moreover, the limited nature of terminal resources available, especially in terms of battery capacity, is one of the most important issues to be addressed in order to prolong their operating time. In order to ensure efficient communications in such networks, much research has already been conducted, especially in the field of routing and transmission technologies. However, conventional approaches adopted in the routing field still suffer from the so-called energy hole problem, usually caused by unbalanced communication loads existing due to difficulties in adaptive route management. To address this issue, the present paper proposes a novel routing algorithm that utilizes ACO-inspired routing based on residual energy of terminals. Operational evaluation reveals its potential to ensure balanced energy consumption and to boost network performance
A Dual-band Circularly-polarized Printed Monopole Antenna for Wi-Fi and WiMAX Applications, Journal of Telecommunications and Information Technology, 2019, nr 4
Full text linkThis paper presents a rectangular-shaped printed monopole antenna with circular polarization for Wi-Fi (2.4–2.484 GHz) and WiMAX (3.3-3.7 GHz) bands. The antenna relies on asymmetric arrangement of the patch with respect to the microstrip feed, in order to generate circular polarization. Dual-band (Wi-Fi and WiMAX) operation is enabled by inserting a slit in the corner of the ground plane. Simulation results show a bandwidth increase of 15.9% (2.2–2.58 GHz) for Wi-Fi, and of 24.16% (3.13–3.99 GHz) for WiMAX applications. Furthermore, beamwidths at the axial ratio of 3 dB equal 48˚ and 51˚ for the x-z plane and y-z planes, respectivel
Measurement of Electromagnetic Field Component Emissions as a Precursor of Emerging Hazard in Coal Mines, Journal of Telecommunications and Information Technology, 2019, nr 4
Full text linkThe article presents the results of research concerning electromagnetic (EM) field emitted by rocks during the process of their destruction. The paper describes a measuring stand designed for subjecting rock samples to axial crushing. During the destruction of rock samples, both components of the electromagnetic field emitted by the rock were recorded. The paper presents the results of research on hard coal samples, presenting the obtained time domain waveforms and frequency spectrum of the emitted EM field components. Further potential uses of tests concerned with EM emitted by rocks are determined. Applications registering EM field in mine environments may provide an early mine collapse warning
Comparison of Multicast Algorithm Evaluation Results in Low and High Multicast Saturation Environments, Journal of Telecommunications and Information Technology, 2019, nr 3
Full text linkThe multicast quality of service-enabled routing is a computationally challenging task. Despite ongoing research efforts, the associated mathematical problems are still considered to be NP-hard. In certain applications, computational complexity of finding the optimal connection between a set of network devices may be a particularly difficult challenge. For example, connecting a small group of participants of a teleconference is not much more complex than setting up a set of mutual point-to-point connections. On the other hand, satisfying the demand for such services as IPTV, with their receivers constituting the majority of the network, requires applying appropriate optimization methods in order to ensure real system execution. In this paper, algorithms solving this class of problems are considered. The notion of multicast saturation is introduced to measure the amount of multicast participants relative to the entire network, and the efficiency of the analyzed algorithms is evaluated for different saturation degrees
A Survey on Data Perception in Cognitive Internet of Things, Journal of Telecommunications and Information Technology, 2019, nr 3
Full text linkA Cognitive Internet of Things (CIoT) is a brand of Internet of Things (IoT) with cognitive and agreeable mechanisms, which are incorporated to advance performance and accomplish insights into real world environments. CIoT can perceive present system’s conditions, analyze the apparent information, make smart choices, and increase the network performance. In this survey paper, we present classifications of data perception techniques used in CIoT. This paper also compares the data perception works against energy consumption, network life-time, resource allocation, and throughput, as well as quality of data and delay. In addition, simulation tools for IoT and their performance are discussed. Finally, we provide the model of cognitive agent-based data perception in CIoT for future research and development, which ensures the network performance in terms of reliability, energy efficient, accuracy, scalable, fault tolerant, and quality of data
Complex Signal Mapping for Improving Spectral Efficiency of Li-Fi Systems, Journal of Telecommunications and Information Technology, 2019, nr 3
Full text linkLight fidelity (Li-Fi) systems based on the orthogonal frequency division multiplexing (OFDM) scheme have gained more attention in the communications circles, as a means to provide high spectral efficiency and ensure stricter data rate requirements for visible light communication (VLC) systems. However, common OFDM schemes employ Hermitian symmetry to obtain a real-valued signal which is necessary in intensity modulation and direct detection (IM/DD) optical systems, at the expense of doubling the required bandwidth. In this paper, a novel transmission scheme for an OFDM-based Li-Fi system is proposed to tackle the issue in question. A new approach to complex signal mapping (CSM), based on the pairing function method, has been developed for Li-Fi systems. It does not require Hermitian symmetry and, hence, saves about 50% of the required bandwidth. Unlike existing OFDM-based VLC approaches, the proposed scheme employs CSM to ensure a real and positive signal without Hermitian symmetry in order to fully utilize the bandwidth available to Li-Fi networks. Simulation results show that the proposed scheme significantly outperforms other systems in terms of spectral efficiency. The CSM-OFDM based Li-Fi system also achieves a good peak-to-average power ratio (PAPR) reduction with acceptable bit-error-rate (BER) performance, compared to conventional approaches
WannaCry Ransomware: Analysis of Infection, Persistence, Recovery Prevention and Propagation Mechanisms, Journal of Telecommunications and Information Technology, 2019, nr 1
Full text linkIn recent years, we have been experiencing fast proliferation of different types of ransomware targeting home users, companies and even critical telecommunications infrastructure elements. Modern day ransomware relies on sophisticated infection, persistence and recovery prevention mechanisms. Some recent examples that received significant attention include WannaCry, Petya and BadRabbit. To design and develop appropriate defense mechanisms, it is important to understand the characteristics and the behavior of different types of ransomware. Dynamic analysis techniques are typically used to achieve that purpose, where the malicious binaries are executed in a controlled environment and are then observed. In this work, the dynamic analysis results focusing on the infamous WannaCry ransomware are presented. In particular, WannaCry is examined, during its execution in a purpose-built virtual lab environment, in order to analyze its infection, persistence, recovery prevention and propagation mechanisms. The results obtained may be used for developing appropriate detection and defense solutions for WannaCry and other ransomware families that exhibit similar behavior
An Improved M-ary Modulation Scheme Based on Chaotic Dynamics, Journal of Telecommunications and Information Technology, 2019, nr 4
Full text linkThis paper proposes an improved chaos-based M-ary modulation system. It reproduces deterministic chaotic dynamics to create M-ary non-coherent modulation. The proposed modulation system transmits data using autonomous chaotic sequences. It separates the chaotic dynamics through the use of interleavers and realigns them through the use deinterleavers. The simulation results show that the improved scheme overperforms its traditional counterpart. The degree of improvement grows as the M-ary order is increased, with a penalty of increased system complexit
A P2P-based Communication Framework for Geo-Location Oriented Networks, Journal of Telecommunications and Information Technology, 2019, nr 1
Full text linkThis paper proposes a novel peer-to-peer communication framework to implement geographical location oriented networks, called G-LocON. Location-based services have been gaining in popularity, as proven by ridesharing and mobile games. Although these services have to construct geolocation oriented networks based on their users’ geographical locations, they completely rely on client/server models to communicate with neighboring terminals. G-LocON provides geolocation oriented device-to-device communication only with the current wireless technologies, such as LTE and Wi-Fi, cooperating with the global positioning system and peer-to-peer overlay networking. G-LocON will serve as a type of a mobile ad-hoc network in which devices located within the focusing area are capable of communicating directly. We developed a primitive Android application to implement the GLocON framework. Evaluation of the solution’s performance has verified the usefulness of the proposed system that offers an admissive transmission delay. Moreover, to confirm the application-related potential of the G-LocON framework, we also show a practical map software in which all neighboring mobile devices present in the focusing area are displayed