Institute of Electron Technology
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2189 research outputs found
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Two Extensions of Trust Management Languages, Journal of Telecommunications and Information Technology, 2020, nr 1
Full text linkThis article is focused on the family of role-based trust management languages (RT). Trust management languages are a useful method of representing security credentials and policies in large distributed access control mechanisms. They provide sets of credentials that are assigned to individual roles performed by the specific entities. These credentials provide relevant information about security policies issued by trusted authorities and define user permissions. RT languages describe the individual entities and the roles that these entities play in a given environment. A set of credentials representing a given security policy defines which entity has the necessary rights to access a specific resource and which entity does not have such rights. This study presents the results of research focusing on the potential of the family of RT languages. Its purpose is to show how security policies may be applied more widely by applying an inference system, and then using the extensions of the credentials, by taking into account time-related information or the conditions imposed with regard to the validity of such credentials. Each of these extensions can be used jointly or separately, offering even a wider range of opportunitie
ICBCA – Improved Cluster Based Channel Allocation in Cognitive Radio Sensor Networks, Journal of Telecommunications and Information Technology, 2020, nr 3
Full text linkWireless sensor networks (WSNs) operate in an overcrowded electromagnetic environment, as the spectrum is shared by various wireless communication technologies. This gives rise to various challenges related to optimized and efficient spectrum utilization. Cognitive radio (CR) has emerged as a solution satisfying this requirement, as it is capable of adapting to the dynamic radio spectrum. Thanks to the deployment of cognitive radio in WSNs, the spectrum may be utilized in a more efficient manner. CR may identify the vacant channels dynamically, allowing the sensor nodes to effectively communicate with each other. In this paper a clustering algorithm known as improved cluster-based channel assignment (ICBCA) is implemented, forming clusters of CR sensor nodes and then selecting vacant channels for data transmission purposes. Simulation results show that ICBCA outperforms existing clustering algorithms in CR sensor network
Flow Aggregation for Energy-Aware Ad-Hoc Wireless Networks Respecting QoS Provisions, Journal of Telecommunications and Information Technology, 2020, nr 1
Full text linkEmerging communication technologies are now leading developers to design IT systems taking into count their energy-related considerations. Much research performed in the area of ad-hoc wireless networks tends to distribute the flows over all nodes of the network, which increases the amount of energy consumed by each node and reduces longevity of the network. To overcome these problems, this paper seeks to aggregate a set of flows within a number of nodes that is as low as possible in order to be capable of routing those flows. This proposal allows to maximize the number of network nodes that may be turned off. The proposed solution was formulated as an integer linear programming (ILP) problem using a set of energy and quality of service (QoS) constraints. This formulation minimizes the total energy consumed by the nodes to construct a topology network that is capable of meeting QoS requirement for a set flows inserted into the network. To evaluate the efficiency of the proposed model, a performance-based comparison was conducted with another routing model. The simulation results show that the proposed model offers better performance in terms of global energy consumption and network loa
A Comprehensive Survey on Resource Management in Internet of Things, Journal of Telecommunications and Information Technology, 2020, nr 4
Full text linkEfficient resource management is a challenging task in distributed systems, such as the Internet of Things, fog, edge, and cloud computing. In this work, we present a broad overview of the Internet of Things ecosystem and of the challenges related to managing its resources. We also investigate the need for efficient resource management and the guidelines given/suggested by Standard Development Organizations. Additionally, this paper contains a comprehensive survey of the individual phases of resource management processes, focusing on resource modeling, resource discovery, resource estimation, and resource allocation approaches based on performance parameters or metrics, as well as on architecture types. This paper presents also the architecture of a generic resource management enabler. Furthermore, we present open issues concerning resource management, pointing out the directions of future research related to the Internet of Thing
Review of Experimental Verification Methods of Gyrotron Quasi-optical Mode Converters, Journal of Telecommunications and Information Technology, 2020, nr 3
Full text linkThis survey presents a review of experimental methods relied upon while implementing gyrotron higher mode generation techniques and performing near electromagnetic field measurements in launcher and quasi-optical mode converters. In particular, the paper focuses on low power (cold) testing of gyrotron quasi-optical mode converters outside of the gyrotron, without the presence of high electromagnetic power and electron beam
Performance Evaluation of the Threshold Call Admission Policy in Multi-rate Loss Systems, Journal of Telecommunications and Information Technology, 2020, nr 2
Full text linkIn this paper we consider a link, characterized by specific capacity, that services multi-rate random or quasirandom traffic. Random traffic is generated by an infinite number of traffic sources, while quasi-random traffic is generated by a finite population of traffic sources. The link is modeled as a multi-rate loss system. Handover and new calls are distinguished. New calls compete for the available bandwidth under a threshold call admission policy. In that policy, a new call of a particular service-class is not allowed to enter the system if the in-service handover and new calls of the same service-class plus the new call, exceed a predefined threshold (which can be different for each service-class). On the other hand, handover calls compete for the available bandwidth based on the complete sharing policy. We show that the steady state probabilities in the proposed models have a product form solution (PFS). The PFS leads to a convolution algorithm for accurate calculation of congestion probabilities and link utilizatio
A Soft-Output STBC Decoder for Aeronautical Telemetry, Journal of Telecommunications and Information Technology, 2020, nr 1
Full text linkAlamouti encoding is a well-known space time block encoding technique used to improve the received signal quality in Rayleigh fading channels. In aeronautical telemetry, this encoding technique is applied to shaped offset quadrature phase shift keying tier generation (SOQPSK-TG) modulation in order to handle the two-antenna issue. It is provided for in telemetry-related IRIG standards. In this paper, we propose a unique decoding architecture for Alamouti-encoded SOQPSK-TG signals, taking advantage of pulse amplitude modulation decomposition with soft and hard outputs. We exploit this result to obtain a Viterbi algorithm (VA) for hard decoding and a soft output Viterbi algorithm (SOVA) for soft and hard decoding, with a twofold benefit: operation using one trellis structure, unlike decoders that are based on the 8-waveforms cross-correlated trellis-coded quadrature modulation (XTCQM) approximation, and very attractive bit error rate performance, as well as a complexity trade-o
Analysis of Selective-Decode and Forward Relaying Protocol over κ-µ Fading Channel Distribution, Journal of Telecommunications and Information Technology, 2020, nr 1
Full text linkIn this work, the performance of selective-decode and forward (S-DF) relay systems over κ-µ fading channel conditions is examined in terms of probability density function (PDF), system model and cumulative distribution function (CDF) of the κ-µ distributed envelope, signal-to-noise ratio and the techniques used to generate samples that rely on κ-µ distribution. Specifically, we consider a case where the sourceto-relay, relay-to-destination and source-to-destination link is subject to independent and identically distributed κ-µ fading. From the simulation results, the enhancement in the symbol error rate (SER) with a stronger line of sight (LOS) component is observed. This shows that S-DF relaying systems may perform well even in non-fading or LOS conditions. Monte Carlo simulations are conducted for various fading parameter values and the outcomes turn out to be a close match for theoretical results, which validates the derivations mad
A Novel System Architecture for an Improved Self-care Solution – Conceptual Design and Key Components, Journal of Telecommunications and Information Technology, 2020, nr 4
Full text linkThe high penetration rate that mobile devices enjoy in to day’s society has facilitated the creation of new digital services, with those offered by operators and content providers standing out. However, even this has failed to encourage consumers to express positive opinions on telecommunication services, especially when compared with other sectors. One of the main reasons of the mistrust shown is the low level of quality of customer service provided an area that generates high costs for the operators themselves, due to the high number of people employed at call centers in order to handle the volume of calls received. To face these challenges, operators launched self-care applications in order to provide customers with a tool that would allow them to autonomously manage the services they have subscribed. In this paper, we present an architecture that provides customized information to customers – a solution that is separate from mobile operating systems and communication technologie
Autonomous Instrumentation for Measuring Spontaneous Electromagnetic Emissions in Mining, Journal of Telecommunications and Information Technology, 2020, nr 4
Full text linkThis article presents the design of an innovative receiver capable of identifying electric and magnetic components of electromagnetic fields. The receiver senses and records electromagnetic disturbances generated as mine tunnels collapse. It offers excellent operating specification and the ability to sense and log magnetic and electrical component strength values in real time. The paper analyzes the data obtained with the use of a system installed in a working mine and attempts to determine hazards resulting from increased rock stress levels that, cause spontaneous EM emission