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2189 research outputs found
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Enhancement of Ground-to-Aircraft Communication Using Audio Watermarking, Journal of Telecommunications and Information Technology, 2019, nr 1
Full text linkThis paper presents research on improving the intelligibility of spoken messages transmitted to aircraft from a ground station. The proposed solution is based on the selective calling (SELCAL) system and the audio watermarking technique. The most important elements of a spoken message (commands, numerical values) are transmitted as a watermark embedded in the speech signal and are displayed to the cockpit crew. The synchronization signal is embedded in SELCAL duo-tones. The proposed system is resistant to resampling and channel noise (at SNR > 25 dB)
Ku Band Bethe Hole Coupler Using Gap Waveguide Technology, Journal of Telecommunications and Information Technology, 2019, nr 3
Full text linkThe gap waveguide technology is a new technique used for designing and fabricating microwave components, ensuring a low-loss and easy fabrication process, especially at high frequencies, and allowing for the production of multilayer structures due to the lack of requirement of an electrical connection between the metal layers of the waveguide structure. This paper presents the design and areas of implementation of single-hole and multi-hole 20 dB Bethe couplers, using the groove gap waveguide (GGW) technology for Ku band. Simulation results show that the operating bandwidth of the proposed design is over 40% wider, and its isolation rate is more than 25 dB higher. By using the multi hole configuration, a bandwidth that is more than 59% wider and the isolation rate of over 30 dB may be obtained
Systematic-RLNC Based Secure and QoS Centric Routing Scheme for WSNs, Journal of Telecommunications and Information Technology, 2019, nr 4
Full text linkIn this paper a highly robust and efficient systematic-random linear network coding (S-RLNC) routing scheme is proposed. Unlike classic security systems, the proposed S-RLNC transmission model incorporates an advanced pre-coding and interleaving concept followed by multigeneration mixing (MGM) based data transmission to assure secure and QoS efficient communication. The proposed S-RLNC MGM based routing scheme exhibits higher throughput (99.5-100%) than the existing NCC-ARQ-WSN protocol (80%). Unlike NCC-ARQ-WSN, the proposed model incorporates multiple enhancements, such as RLNC concept, systematic network coding, MGM concept, IBF provision and redundant packet optimization. Combined, all these optimizations have strengthened the proposed S-RLNC MGM to exhibit optimum performance for secure and QoS-centric communication over WSN
LoCO: Local Cooperative Data Offloading System Based on Location Information, Journal of Telecommunications and Information Technology, 2019, nr 1
Full text linkThe development of high speed mobile networks and the widespread use of smartphones have enabled users to easily obtain large data volumes via the Internet. This causes a heavy consumption of network resources, a burden on the available bandwidth. To solve such problems, a data offloading method with a wireless LAN access point has been used to distribute traffic from mobile to fixed networks. However, the method using wireless LAN access points can only change the communication paths but cannot reduce the overall traffic. This paper proposes a local cooperative data offloading system (LoCO) that reduces the overall traffic by sharing data, with direct communication between neighbors based on their location-related information. Moreover, the authors implemented the LoCO system on Android smartphones and clarified its performance in comparison with a traditional client/server system through experiments to download data in a real-world environment
Method for Determining Broadcaster Advised Emergency Wake-up Signal for ISDB-T Digital Television Receivers, Journal of Telecommunications and Information Technology, 2019, nr 1
Full text linkThere is a way to automatically wake up television receivers when a broadcaster sends out an emergency alert. In the Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) digital television standard, the emergency wake-up procedure is called an Emergency Warning System (EWS). In ISDB-T, the special signal is embedded in a control message known as transmission and modulation configuration control (TMCC). However, improper identification of the wake-up signal, often encountered in mobile reception, leads to unnecessary wake ups. In this paper, a method of reliably determining a wake-up signal is proposed by assuming that broadcasters will not change the TMCC message except for the wake-up signal when the broadcaster sends out an emergency alert. A change in the wake-up bit leads to variation parity, and the proposed method also relies on such variations. Mutual information to be obtained by the wake-up receiver is evaluated using the memoryless binary asymmetric channel model. Results showed that the proposed method provided mutual information even at a Eb/N₀ being lower than 10 dB. Mutual information of the proposed method with intermittent reception is also analyzed as a function of the duty ratio of the intermittent receiver
Electromagnetic Scattering by a Cylinder in a Lossy Medium of an Inhomogeneous Elliptically Polarized Plane Wave, Journal of Telecommunications and Information Technology, 2019, nr 4
Full text linkIn this paper, a rigorous theoretical approach, adopted in order to generalize the Vectorial CylindricalHarmonics (VCH) expansion of an inhomogeneous elliptically polarized plane wave, is presented. An application of the VCH expansion to analyze electromagnetic field scattered by an infinite circular cylinder is presented. The results are obtained using the so-called complex-angle formalism reaching a superposition of Vectorial Cylindrical-Harmonics. To validate the method, a Matlab code was implemented. Also, the validity of the methodology was confirmed through some comparisons between the proposed method and the numerical results obtained based on the Finite Element Method (FEM) in the canonical scenario with a single cylinde
Neuroplasticity and Microglia Functions Applied in Dense Wireless Networks, Journal of Telecommunications and Information Technology, 2019, nr 1
Full text linkThis paper presents developments in the area of brain-inspired wireless communications relied upon in dense wireless networks. Classic approaches to network design are complemented, firstly, by the neuroplasticity feature enabling to add the learning ability to the network. Secondly, the microglia ability enabling to repair a network with damaged neurons is considered. When combined, these two functionalities guarantee a certain level of fault-tolerance and self-repair of the network. This work is inspired primarily by observations of extremely energy efficient functions of the brain, and of the role that microglia cells play in the active immune defense system. The concept is verified by computer simulations, where messages are transferred through a dense wireless network based on the assumption of minimized energy consumption. Simulation encompasses three different network topologies which show the impact that the location of microglia nodes and their quantity exerts on network performance. Based on the results achieved, some algorithm improvements and potential future work directions have been identified
Journal of Telecommunications and Information Technology, Load Balancing Based on Optimization Algorithms: An Overview, 2019, nr 4
Full text linkCombinatorial optimization challenges are rooted in real-life problems, continuous optimization problems, discrete optimization problems and other significant problems in telecommunications which include, for example, routing, design of communication networks and load balancing. Load balancing applies to distributed systems and is used for managing web clusters. It allows to forward the load between web servers, using several scheduling algorithms. The main motivation for the study is the fact that combinatorial optimization problems can be solved by applying optimization algorithms. These algorithms include ant colony optimization (ACO), honey bee (HB) and multi-objective optimization (MOO). ACO and HB algorithms are inspired by the foraging behavior of ants and bees which use the process to locate and gather food. However, these two algorithms have been suggested to handle optimization problems with a single-objective. In this context, ACO and HB have to be adjusted to multiobjective optimization problems. This paper provides a summary of the surveyed optimization algorithms and discusses the adaptations of these three algorithms. This is pursued by a detailed analysis and a comparison of three major scheduling techniques mentioned above, as well as three other, new algorithms (resulting from the combination of the aforementioned techniques) used to efficiently handle load balancing issue
Parallel Algorithms for Forward and Back Substitution in Linear Algebraic Equations of Finite Element Method, Journal of Telecommunications and Information Technology, 2019, nr 4
Full text linkThis paper considers several algorithms for parallelizing the procedure of forward and back substitution for high-order symmetric sparse matrices on multi-core computers with shared memory. It compares the proposed approaches for various finite-element problems of structural mechanics which generate sparse matrices of different structure
Fuzzy Clustering with Multi-Constraint QoS Service Routing in Wireless Sensor Networks, Journal of Telecommunications and Information Technology, 2019, nr 1
Full text linkThis paper presents a fuzzy logic-based, service differentiated, QoS aware routing protocol (FMSR) offering multipath routing for WSNs, with the purpose of providing a service differentiated path meant for communication between nodes, based on actual requirements. The proposed protocol initially forms a cluster by fuzzy c-means. Next, the building of a routing follows, so as to establish multiple paths between nodes through the modified QoS k-nearest neighborhood, based on different QoS constraints and on optimum shortest paths. If one node in the path fails due to lack of residual energy, bandwidth, packet loss, delay, an alternate path leading through another neighborhood node is selected for communication. Simulation results show that the proposed protocol performs better in terms of packet delivery ratio, delay, packet drop ratio and throughput compared to other existing routing protocols