Showing papers in "Journal of telecommunications and information technology in 2021"

A Level-Based Approach to Prioritize Telecommunications R&D

Abstract: In this paper, an approach to evaluate R&D projects in telecommunications is presented. These projects have particular features that cannot be properly incorporated by classical evaluation methods. This approach incorporates different criteria, both quantitative and qualitative, and also management flexibility and uncertainty. Thus, it is an approach that can be applied to real data of R&D projects in a telecommunications company. Keywords— multicriteria decision support, R&D project evalu-

Artificial Magnetic Conductor-based Millimeter Wave Microstrip Patch Antenna for Gain Enhancement

Abstract: In this paper, a small (20 × 20 × 2.4 mm) loaded microstrip patch antenna (MPA) with an asymmetric artificial magnetic conductor (AMC) as a ground plane is designed for millimeter wave applications. Two AMC structures are proposed; one has the property of a 0◦ reflection phase around 28.4 GHz, with a symmetric geometry, which makes the reflection phase insensitive to variations in both polarization and incident angle. This symmetric AMC structure ensures angular stability which is considered as a major requirement when periodic structures are used as antenna ground planes. The other structure is characterized by an asymmetric geometry and shows an interesting behavior around 28.6 GHz, where a discontinuity in the reflection phase appeared due to the fact that surface impedance nature changed from purely capacitive to purely inductive. This paper studies the effects of the two proposed AMC structures on the performance of MPAs, by using an array of 8 × 8 unit cell elements as an artificial ground plane. Simulation results show that an MPA with a symmetric AMC ground plane offers better impedance matching and a wider bandwidth. Compared with conventional MPAs, gain is enhanced and directivity is improved as well. As far as an MPA with an asymmetric AMC ground plane is concerned, its performance in terms of gain and directivity is higher than that of the conventional solution. Keywords—artificial magnetic conductor, gain enhancement, microstrip patch antenna, millimeter wave, reflection phase.

Residual Energy-Aware Clustering Transformation for LEACH Protocol

Abstract: Energy is one of the crucial performance parameters in wireless sensor networks (WSNs). Enhancement of network lifetime is an important consideration as well. Low energy-aware clustering hierarchy (LEACH) is one of the protocols proposed for WSNs. In this paper, a residual energy-aware clustering transformation protocol for LEACH (REACT-LEACH), enhancing performance of LEACH by introducing a clustering mechanism, is proposed. The proposed cluster head (CH) rotation and cluster reformation processes are more effective in REACT-LEACH, as residual energy is considered to be one of the metrics. Performance of REACT-LEACH is validated based on simulations

LEES: a Hybrid Lightweight Elliptic ElGamal-Schnorr-Based Cryptography for Secure D2D Communications

Abstract: Device-to-device (D2D) communications in 5G networks will provide greater coverage, as devices will be acting as users or relays without any intermediate nodes. However, this arrangement poses specific security issues, such as rogue relays, and is susceptible to various types of attacks (impersonation, eavesdropping, denial-of-service), due to the fact that communication occurs directly. It is also recommended to send fewer control messages, due to authenticity- and secrecy related prevailing requirements in such scenarios. Issues related to IoT applications need to be taken into consideration as well, as IoT networks are inherently resource-constrained and susceptible to various attacks. Therefore, novel signcryption algorithms which combine encryption with digital signatures are required to provide secure 5G IoT D2D communication scenarios in order to protect user information and their data against attacks, without simultaneously increasing communication costs. In this paper, we propose LEES, a secure authentication scheme using public key encryption for secure D2D communications in 5G IoT networks. This lightweight solution is a hybrid of elliptic curve ElGamal-Schnorr algorithms. The proposed scheme is characterized by low requirements concerning computation cost, storage and network bandwidth, and is immune to security threats, thus meeting confidentiality, authenticity, integrity and non-repudiation-related criteria that are so critical for digital signature schemes. It may be used in any 5G IoT architectures requiring enhanced D2D security and performance

Studying and Modeling the Performance of the TCM-STBC Systems in the Rayleigh Channel

Abstract: Multiple-input multiple-output (MIMO) systems will play an important role in future generations of wireless networks. Space-time block code (STBC) and space-time trellis code (STTC) are two techniques that may be used in multiantenna radio systems. This paper aims, most importantly, to study the performance of STBC systems at different values of such parameters as spectral efficiency, matrix codes and constellations. A performance comparison between STBC and STTC schemes is performed. In order to show the efficiency of the system’s ability to communicate with uncoded and coded transmission structures over AWGN and Rayleigh channels, the trellis-coded modulation (TCM) is introduced. The results obtained show that the proposed TCM-STBC system model, using one and two receiving antennas, improves the performance of Rayleigh channel communication systems at 9.5 dB and 11.5 dB for a BER of 10−5. Keywords—BER, MIMO, SNR, STBC, STTC, TCM, TCMSTBC.

5G Is Out There: How to Ride the Market Storm and Thrive

Abstract: We examine the changes in the commercial model adopted by the mobile ICT industry, due to the advent of 5G technology. This includes consideration of the challenges involved in rolling out a new infrastructure, which new markets this is likely to open up and how this affects partnering decisions. We show that as technology horizons expand, their degree of overlap increases and previously complimentary technologies may compete with each other, impacting the size of the addressable market. It is expected that 5G, whilst supporting its existing markets, will offer additional machine to machine, low latency and highly reliable services. We consider the synergies and the drivers for adoption for the wider 5G propositions and consider the impetus for more bandwidth and services and how the new technology impacts selling approaches. We identify the risks and uncertainties for the network providers and the likely requirements for a sustainable 5G business model and will describe our view of the steps necessary for a 5G successful outcome

COVID-19 pandemic and internet traffic in Poland: Evidence from selected regional networks

Abstract: The COVID-19 pandemic has forced governments all over the world to impose lockdowns keeping citizens at home in order to limit the virus spread rate. The paper compares weekly traffic samples captured in the selected nodes of the network managed by NASK - National Research Institute during the pre-lockdown period, i.e. between January 27 and February 3, 2020, with those captured between March 30 and April 6, 2020, i.e. after the lockdown was announced. The presented results show changes in network traffic observed during the periods of time in question and illustrate the evolution in the popularity of top network services. © 2021 National Institute of Telecommunications. All rights reserved.

Orthogonal Harmonic Signals of the Generalized Class

Abstract: Telecommunications transmission technologies with OFDM rely on orthogonal harmonic signal (OHS) systems. The criteria applicable to synthesizing OHS systems of the generalized class, including both classical signals and signals whose duration exceeds the orthogonality interval, have been considered. The problems of minimizing the effective width of the spectrum of the generalized class OHS have been solved. Estimates of the efficiency of the generalized class OHS have been given. Keywords—Fourier transformation, OFDM, orthogonal harmonic signals, orthogonality interval, signal envelope.

Autonomous Instrumentation for Measuring Spontaneous Electromagnetic Emissions in Mining

Abstract: This 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 emissions.

FANET Drone’s 4K Data Applications, Mobility Models and Wi-Fi IEEE802.11n Standards

Abstract: With growing popularity of unmanned aerial vehicles (UAVs), the importance of flying ad-hoc networks (FANETs) is enhanced by such applications as 4K video recording, communications in search and rescue missions and goods deliveries, to name just a few. This, in turn, stimulates research on different topologies of networks existing between UAVs, with studies in this field being essential to improving performance of such networks. Several problems must be solved to effectively use UAVs in order to offer stable and reliable massive data transmission capabilities, taking into consideration quickly changing FANET topologies, types of routing, security issues, etc. In this paper, a comprehensive evaluation of FANETs used by UAVs is presented in terms of communication network challenges, data types, mobility models and standards applied in order to achieve best performance. The evaluation presented herein covers such areas as data throughput, retransmission attempts and delay. Keywords—4K data transmission, FANET, mobility models,

Vlasov Launcher Diagrammatic Design Using the RT Method

Abstract: In this paper, a simple and fast method relied upon for designing a Vlasov launcher with a helical cut is proposed. The method is based on graphic interpretation of analytical relationships that link wave parameters (EM field mode) to the launcher’s geometrical dimensions. Using the ray tracing method, a simplified graphic analysis may be carried out. The results obtained are not significantly different from those of rigorous full-wave analyzes. The family of normalized curves that is created in the process greatly facilitates the stage of optimizing the geometrical parameters of the Vlasov launcher

Political and Economic Contexts of Implementing 5G in Poland and in Selected European Countries

Abstract: The technology race to achieve the position of an economic leader is a phenomenon that has been taking place all over the world. The 5G technology has become a vital component of this race over the recent years. The technical capabilities it offers and the role it may play in the economy have become the subject of political debate and are at the very core of the “war for technology” between two superpowers: China and the United States. The European Union is aware of the fact that the position Europe enjoys on the international arena depends, to a large extent, on how quickly European countries will develop and implement 5G. Are individual European member states capable of seamlessly implementing the assumptions of strategies and plans concerned with the development of 5th generation technologies? Will the security of 5G networks be ensured in Europe? These are just some of the issues that are analyzed in this article with their economic and political context taken into consideration. A broader perspective is presented, with primary focus on the global geopolitical situation and on the conflict between China and the United States. The study was conducted by relying on an in-depth analysis of strategic state documents, reports drawn up by institutions tasked with implementing and monitoring the development of 5G technology, as well as literature on the subject and online resources

Location Estimation of Nodes in Underwater Acoustic Sensor Networks

Abstract: The 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. Keywords—location estimation, trapezoid, UASN.

5G New Business Opportunities – New Business Models, Pricing, and Use Cases

Abstract: This paper addresses how network operators may gain a reasonable return on their investment into 5G infrastructure. It first considers the 5G mobile network costs structure then applies this to three typical use cases

Digital Predistortion of Wideband Signals with Reduced Complexity Based on Feedback Wiener System

Abstract: Digital predistortion (DPD) using baseband signals is commonly used for power amplifier linearization. This paper is devoted to this subject and aims to reduce DPD complexity. In this study, we propose a structure that allows to decrease the number of DPD parameters by using multiple blocks, with each one of them dedicated to characterizing the non-linear behavior and/or memory effects. Such a structure is based on the feedback Wiener system, involving a FIR filter used as a feedback path to reproduce the PA inverse dynamics. A memory polynomial block (MP) is inserted as the final element to minimize the modeling errors. A relevant model identification method, based on an iterative algorithm, has been developed as well. The proposed architecture is used for the linearization of a commercial class-AB LDMOS RF PA by NXP Semiconductors, in wideband communication systems. Comparison of performance with the conventional generalized memory polynomial model (GMP) shows that the proposed model offers similar results, with its advantage consisting in the reduced number of parameters.

Optimization of Gyrotron Resonator’s Dimensions

Abstract: This paper explains the procedure of determining the initial dimensions of a gyrotron resonator. In particular, the paper discusses which geometrical parameters impact the wave properties of the resonator. The solution is implemented using Matlab software and estimations are performed with the use of the SMath Studio spreadsheet. Keywords—gyrotron design, cold cavity, Matlab code.

Suboptimal Approach to Distributed Detection in Cognitive Radio Networks

Abstract: In 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. Keywords—cognitive radio, distributed detection, energy detector, myopic policy, spectrum sensing.

Evaluation of Reliability of Mobile ICT Services

Abstract: This 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. Keywords—reliability, ICT mobile services, user satisfaction.

Optimal Voting Rule and Minimization of Total Error Rate in Cooperative Spectrum Sensing for Cognitive Radio Networks

Abstract: In 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. Keywords—cognitive radio, energy detection, optimization, spectrum sensing.