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2189 research outputs found
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Fusion of Depth and Thermal Imaging for People Detection, Journal of Telecommunications and Information Technology, 2021, nr 4
Full text linkThe methodology presented in this paper covers the topic of automatic detection of humans based on two types of images that do not rely on the visible light spectrum, namely on thermal and depth images. Various scenarios are considered with the use of deep neural networks being extensions of Faster R-CNN models. Apart from detecting people, independently, with the use of depth and thermal images, we proposed two data fusion methods. The first approach is the early fusion method with a 2-channel compound input. As it turned out, its performance surpassed that of all other methods tested. However, this approach requires that the model be trained on a dataset containing both types of spatially and temporally synchronized imaging sources. If such a training environment cannot be setup or if the specified dataset is not sufficiently large, we recommend the late fusion scenario, i.e. the other approach explored in this paper. Late fusion models can be trained with single-source data. We introduce the dual-NMS method for fusing the depth and thermal imaging approaches, as its results are better than those achieved by the common NM
Suboptimal Approach to Distributed Detection in Cognitive Radio Networks, Journal of Telecommunications and Information Technology, 2021, nr 1
Full text linkIn this paper a dynamic spectrum access (DSA) concept is explored for mitigating the paucity of spectral bandwidth in cognitive radio (CR) for opportunistic, dynamic access of the spectrum without any interference. Dynamic spectrum access schemes are proposed for a distributed cognitive radio network consisting of one secondary user (SU) and many primary users (PUs). The SU has to make decisions for accessing PU channels within discrete time slots. The design of sensing and access strategies that govern channel choice in each slot for near-optimal throughput performance of the SU may be formulated as a partially observable Markov decision process (POMDP). Furthermore, it is considered that the SU incurs a cost whenever it switches to a different channel. The switching cost is expressed in terms of delay, packet loss and packet overhead. In this work, the SU access policy based on a myopic approach is proposed and evaluated
Has the Internet Saved the Economy? Modeling Impact of ICT Sector and COVID-19 on GDP, Journal of Telecommunications and Information Technology, 2021, nr 4
Full text linkThis paper presents the influence of the COVID19 pandemic on gross domestic product (GDP) per capita for the 27 countries of the European Union. A panel model with fixed effects was applied to a dataset from 2010 to 2020. The analysis covered 13 independent variables, including nine related to the telecommunications market, and assessed their impact on GDP per capita. A variable related to the number of COVID-19 deaths per one thousand inhabitants was then added to the model. The results showed that COVID-19 is a significant factor and is negatively correlated with GDP per capita. The analysis described in the article has also shown that the importance of the ICT sector increased during the pandemic, i.e. the household broadband Internet variable became statistically significan
Accurate Location of Fiber Cable Fault with OTDR, Journal of Telecommunications and Information Technology, 2021, nr 4
Full text linkThe paper reviews the factors limiting the accuracy of locating a fiber optic cable fault when using an optical time domain reflectometer (OTDR) and describes an error estimation method for typical use cases. The primary source of errors lies in the complex relationship between the length of the optical fiber (measured by OTDR), its routing, cable design depending on cable design and type of installation (i.e. duct, directly buried, aerial) as well as the spare lengths used for service purposes. The techniques which considerably improve the accuracy of the fault localization processes are presented, the importance of accurate documentation of the network and of referencing the fault location to the nearest splice instead of end of the line are discussed, as is the absence of cable helix factor in data sheet
Security Verification in the Context of 5G Sensor Networks, Journal of Telecommunications and Information Technology, 2021, nr 2
Full text linkIn order to develop reliable safety standards for 5G sensor networks (SN) and the Internet of Things, appropriate verification tools are needed, including those offering the ability to perform automated symbolic analysis process. The Tamarin prover is one of such software-based solutions. It allows to formally prove security protocols. This paper shows the modus operandi of the tool in question. Its application has been illustrated using an example of an exchange of messages between two agents, with asynchronous encryption. The scheme may be implemented, for instance, in the TLS/DTLS protocol to create a secure cryptographic key exchange mechanism. The aim of the publication is to demonstrate that automated symbolic analysis may be relied upon to model 5G sensor networks security protocols. Also, a use case in which the process of modeling the DTLS 1.2 handshake protocol enriched with the TCP SYN Cookies mechanism, used to preventing DoS attacks, is presente
Analysis of the Discrete-time Multi-queue System with a Cycle-based Scheduler, Journal of Telecommunications and Information Technology, 2021, nr 2
Full text linkThis paper presents an analysis of a discrete-time multi-queue system handling a number of packet streams. The analysis focuses on calculating system state distribution and packet sojourn time distribution. The method relied upon for determining system state distribution is based on creating a number of equations that are solved numerically. Next, based on the distribution calculated in such a manner, we derive relations for packet sojourn time distribution. The models studied may be useful for instance in a system supporting a number of virtual links (each of a constant bitrate) that share a common physical link. Isolation of performance of those virtual links needs to be assured. Finally, we present some exemplary numerical results showing the usefulness of the proposed analysis for supporting the system dimensioning proces
Location Estimation of Nodes in Underwater Acoustic Sensor Networks, Journal of Telecommunications and Information Technology, 2021, nr 1
Full text linkThe paper presents a location estimation scheme for underwater acoustic sensor networks. During the first phase, the sink node begins the trapezoid formation process by activating the trapezoid formation agent. It stores relevant information in the sink’s knowledge base and in the node’s knowledge base, and also develops the search data structure required for locating the node. During the second phase, the position of the node is determined by utilizing the search data structure. Identification of the location of all nodes by traveling across the trajectory may be performed as well, as an alternative approach. When identifying the location of one node, the estimation is performed based on the search data structure. When determining the position of all nodes, the sink node agent travels along the defined trajectory and transmits beacon messages which contain the real-time location at specific points. The anchor node agent measures the signal strength and localizes itself and begins estimating the locations of other nodes within the trapezoids, using location estimation techniques. Various performance parameters are used to validate the proposed scheme
Markov Decision Process based Model for Performance Analysis an Intrusion Detection System in IoT Networks, Journal of Telecommunications and Information Technology, 2021, nr 3
Full text linkIn this paper, a new reinforcement learning intrusion detection system is developed for IoT networks incorporated with WSNs. A research is carried out and the proposed model RL-IDS plot is shown, where the detection rate is improved. The outcome shows a decrease in false alarm rates and is compared with the current methodologies. Computational analysis is performed, and then the results are compared with the current methodologies, i.e. distributed denial of service (DDoS) attack. The performance of the network is estimated based on security and other metric
A Shared Cybersecurity Awareness Platform, Journal of Telecommunications and Information Technology, 2021, nr 3
Full text linkEnsuring a good level of cybersecurity of global IT systems requires that specific procedures and cooperation frameworks be adopted for reporting threats and for coordinating the activities undertaken by individual entities. Technical infrastructure enabling safe and reliable online collaboration between all teams responsible for security is an important element of the system as well. With the above taken into consideration, the paper presents a comprehensive distributed solution for continuous monitoring and detection of threats that may affect services that provision is essential to security and broadly understood the state’s economic interests. The said solution allows to collect, process and share distributed knowledge on hazard events. The partnership-based model of cooperation between the system’s users allows the teams to undertake specific activities at the central level, facilitates global cyber threat awareness, and enhances the process of predicting and assessing cyber risks in order to ensure a near-realtime response. The paper presents an overview of the system’s architecture, its main components, features, and threat intelligence tools supporting the safe sharing of information concerning specific events. It also offers a brief overview of the system’s deployment and its testing in an operational environment of NASK’s Computer Security Incident Response Team (CSIRT) and Security Operation Center (SOC) of essential services operator
Impact of Structures on the Operation of Air Traffic Radiolocation and Radionavigation Surveillance Systems, Journal of Telecommunications and Information Technology, 2021, nr 4
Full text linkThe article describes interference affecting the operation of radiolocation and radionavigation devices used in the air traffic surveillance systems, caused by the proximity of building structures. The impact of a hypothetical structure on the operation of primary and secondary air traffic surveillance radars and DVOR/DME beacons was simulated. The results of this simulation are presented in the form of airspace sectors in which false identification of aircraft may occur, and where it will not be possible to identify aircraft or use beacons due to the certain portion of airspace being in the shadow created by the structure. Analysis of the possibility of the PSR radar receiver being blocked by a strong signal reflected from a nearby building was performed as wel