Institute of Electron Technology
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Optimal Voting Rule and Minimization of Total Error Rate in Cooperative Spectrum Sensing for Cognitive Radio Networks, Journal of Telecommunications and Information Technology, 2021, nr 1
Full text linkIn cognitive radio technology, spectrum sensing is essential for detecting spectrum holes which may be allotted to secondary users. In this paper, an optimal voting rule is used for cooperative spectrum sensing while minimizing the total error rate (TER). The proposed spectrum sensing method is more energy-efficient and may be implemented in practice. It is relied upon in an improved energy detector whose utilization depends on the presence or absence of the primary user. Expressions for false alarm and missed detection probabilities are derived in the paper as well. Overall performance is analyzed both for AWGN and Rayleigh fading channels, in the presence of additive white Gaussian noise (AWGN). The optimum voting rule is applied to the cooperative spectrum sensing process in order to identify the optimum number of sensing nodes and the detection threshold. Finally, an energy-efficient spectrum sensing algorithm is proposed, requiring a lower number of cognitive users for a given error bound
Tractography Methods in Preoperative Neurosurgical Planning, Journal of Telecommunications and Information Technology, 2021, nr 3
Full text linkKnowledge of the location of nerve tracts during the surgical preoperative planning stage and during the surgery itself may help neurosurgeons limit the risk of causing neurological deficits affecting the patient’s essential abilities. Development of MRI techniques has helped profoundly with in vivo visualization of the brain’s anatomy, enabling to obtain images within minutes. Different methodologies are relied upon to identify anatomical or functional details and to determine the movement of water molecules, thus allowing to track nerve fibers. However, precise determination of their location continues to be a labor-intensive task that requires the participation of highly-trained medical experts. With the development of computational methods, machine learning and artificial intelligence, many approaches have been proposed to automate and streamline that process, consequently facilitating image-based diagnostics. This paper reviews these methods focusing on their potential use in neurosurgery for better planning and intraoperative navigatio
Developing RF Power Sensor Calibration Station in Direct Comparison Transfer System using Vector Network Analyzer, Journal of Telecommunications and Information Technology, 2021, nr 3
Full text linkCalibration of RF power sensors is crucial issue in RF power measurements. Many calibration laboratories use the direct comparison transfer system with a signal generator and a power splitter. Increasing performance of modern vector network analyzers makes it possible to perform a power sensor calibration with acceptable uncertainties. The main advantage when using a VNA is a simple measurement setup with a wide frequency range (up to 50 GHz, limited only by the VNA and the standard power sensor), where all of required components, i.e. signal generator, a directional coupler and a reference power indicator are built in the VNA technology. This paper reports performing a VNA-based RF power sensors calibration for 10 MHz – 18 GHz band, carried out in the Laboratory of Electric, Electronic and Optoelectronic Metrology at the National Institute of Telecommunications in Warsaw, Poland. In order to validate the proposed solution two of power sensors were calibrated at a reference laboratory. The validation consisted of two steps. At first, one of those characterized power sensors was calibrated at our laboratory in direct comparison transfer system. Finally, the results obtained from the VNA-based system were compared with the previously obtained one
Editors’ Note on the Special Section, Journal of Telecommunications and Information Technology, 2021, nr 2
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Evaluation of Reliability of Mobile ICT Services, Journal of Telecommunications and Information Technology, 2021, nr 1
Full text linkThis article discusses common problems with reliability and availability of ICT services, mainly in mobile networks. Internet access-related services have been examined and traditional service quality assessment methods have been compared with the proposed solutions, with the primary focus placed on availability and reliability of mobile services. The required parameter values describing reliability and quality levels have been defined and proposed
High-resolution Direction of Arrival Estimation Method Based on Sparse Arrays with Minimum Number of Elements, Journal of Telecommunications and Information Technology, 2021, nr 1
Full text linkRegular fully filled antenna arrays have been widely used in direction of arrival (DOA) estimation. However, practical implementation of these arrays is rather complex and their resolutions are limited to the beamwidth of the array pattern. Therefore, higher resolution and simpler methods are desirable. In this paper, the compressed sensing method is first applied to an initial fully filled array to randomly select the most prominent and effective elements which are used to form the sparse array. To keep the dimension of the sparse array equal to that of the fully filled array, the first and the last elements were excluded from the sparseness process. In addition, some constraints on the sparse spectrum are applied to increase estimation accuracy. The optimization problem is then solved iteratively using the iterative reweighted l1 norm. Finally, a simple searching algorithm is used to detect peaks in the spectrum solution that correspond to the directions of the arriving signals. Compared with the existing scanned beam methods, such as the minimum variance distortionless response (MVDR) technique, and with subspace approaches, such as multiple signal classification (MUSIC) and ESPIRT algorithms, the proposed sparse array method offers better performance even with a lower number of array elements and in severely noisy environments. Effectiveness of the proposed sparse array method is verified via computer simulations
Enabling Power Beacons and Wireless Power Transfers for Non-Orthogonal Multiple Access Networks, Journal of Telecommunications and Information Technology, 2021, nr 3
Full text linkThis paper studies downlink cellular networks relying on non-orthogonal multiple access (NOMA). Specifically, the access point (AP) is able to harvest wireless power from the power beacon (PB). In the context of an AP facilitated with multiple antennas, the transmit antenna selection procedure is performed to process the downlink signal, with the transmission guaranteed by energy harvesting. Therefore, a wireless power transfer-based network is introduced to overcome power outages at the AP. In particular, an energy-constrained AP harvests energy from the radio frequency signals transmitted by the PB in order to assist in transmitting user data. Outage performance and ergodic capacity are evaluated with the use of closed-form expressions. In order to highlight some insights, approximate computations are provided. Finally, numerical simulations are performed to confirm the benefits of combining the downlink NOMA transmission and the transmit power scheme at the AP in order to serve a multitude of user
C-V2X Communications for the Support of a Green Light Optimized Speed Advisory (GLOSA) Use Case, Journal of Telecommunications and Information Technology, 2021, nr 2
Full text linkRapid expansion of 5G affects a number of sectors, including vehicular communications relying on cooperative intelligent transportation systems (C-ITS). More specifically, in the context of the Internet of Vehicles (IoV), a particular emphasis is placed on modern cellular V2X (C-V2X) technologies aiming to further improve road safety. This work originates from the detailed scope of the ongoing 5G-DRIVE research project promoting cooperation between the EU and China, with the aim of demonstrating IoV services that rely on vehicle-to-infrastructure (V2I) communications. With the C-V2X approach serving as a point of departure, we analyze and describe a specific green light-optimized speed advisory (GLOSA) use case, for which we provide a detailed descriptive framework, a proposed architectural framework for trials, as well as specific KPIs for the joint assessment of trials between the EU and China. We also discuss the context for performance test procedures to be conducted as part of the intended trials. GLOSA provides end-users with short-term information on upcoming traffic light status to optimize traffic flows, help prevent speed limit violations, improve fuel efficiency, and reduce pollutio
Ka Band-pass Filter Based on SIW Technology for Wireless Communications, Journal of Telecommunications and Information Technology, 2021, nr 2
Full text linkThe paper proposes a new third-order Chebyshev bandpass filter based on the substrate integrated waveguide (SIW) manufacturing technology using an inductive iris and a defected ground structure (DGS) station to resonate in the Ka frequency band, intended for wireless communication applications. All steps that are necessary for designing such a filter have been described in detail based on specific analytical equations harnessed to calculate the different synthesizable parameters of the proposed band-pass filter design, such as the coupling matrix, quality coefficients and initial geometric dimensions. The filter’s ideal frequency response is extracted from an equivalent circuit employing localized elements developed with the use of Design Microwave Office Software. Otherwise, HFSS is employed to set the initial parameters of the proposed topology that will not meet the target specifications defined previously. Accordingly, optimization procedures are necessary for different SIW band-pass filter parameters to reach a high frequency response for the proposed design. The detailed results presented show high efficiency of the SIW technology that offers good performance with lower filter volumes. Two topologies have been developed and then optimized to demonstrate the usefulness of EM softwar