No. 4 (2023)
Explore the current issue of the JTIT
Current issue of Journal of Telecommunication and Information Technology (JTIT) contains latest high quality original articles and the results of key research projects of recognized scientists that deal with theories and research on broad scope of telecommunications and information technology with current literature based on theory, research and practice.
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The Journal of Telecommunications and Information Technology is the official publication of the National Institute of Telecommunications, the leading government organization dealing with the development of telecommunications technologies.
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Published:
2023-10-31
ARTICLES FROM THIS ISSUE
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Deep Classifiers and Wavelet Transformation for Fake Image Detection
Abstract
The paper presents the computer system for detecting deep fake images in video films. The system is based on applying
continuous wavelet transformation combined with the ensemble of classifiers composed of a few convolutional neural networks of diversified architecture. Three different forms of forged images taken from the Face-Forensics++ database are considered in numerical experiments. The results of experiments on the application of the proposed system have shown good performance in comparison to other actual approaches to this problem. -
An Efficient Controller Placement Algorithm using Clustering in Software Defined Networks
Abstract
Software-defined networking (SDN) is an emerging network paradigm that separates the control plane from data plane and provides programmable network management. The control plane within SDN is responsible for decision-making, while packet forwarding is handled by the data plane based on flow entries defined by the control plane. The placement of controllers is an important research issue that significantly impacts performance of SDN. In this work, we utilize clustering algorithms to group networks into multiple clusters and propose an algorithm for optimal controller placement within each cluster. Initially, using the silhouette score, we determine the optimal number of controllers for various topologies. Additionally, to enhance network performance, we employ the meeting point algorithm to calculate the optimal location for placing the controller within each cluster. We implement the proposed work in the Mininet emulator with POX as the SDN controller. Furthermore, we compare our proposed approach to existing work in terms of throughput, delay, and jitter using six topologies from the Internet Zoo dataset.
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Designing Eight-port Antenna Array for Multi-Band MIMO Applications in 5G Smartphones
Abstract
This article introduces a dual-functional low-profile compact multiple input multiple output (MIMO) antenna array for multi-band communication in 5G smartphones. The proposed eight elements of the antenna array form two different 4×4 MIMO systems. The first four elements are placed at the four mobile corners and operate in a single band of 3.445-3.885 GHz for 5G n77 and n78 applications. The other system, in which four antennas are positioned in the middle of the terminal board, supports two wide bands of 1.684-2.300 GHz and 4.432-5.638 for n2, n3, n39, n65, n66, n79, and WLAN applications. The second iteration of a modified Peano-type fractal geometry served as the design foundation for the proposed antenna element. The system's ground plane design is based on self-isolated and spatial diversity methods. The single-band MIMO system's isolation is better than 23 dB. In the dual-band MIMO system that is based on self-isolation, isolation equals approximately 16 dB in the higher band and 10 dB in the lower band. To evaluate performance, radiation-related and total antenna efficiencies, scattering parameters and gains were investigated. Additionally, ECCs have been considered to evaluate MIMO performance. According to the results, such design constitutes a valuable option for MIMO applications in 5G smartphones.
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Synthesizing Non-Uniformly Excited Antenna Arrays Using Tiled Subarray Blocks
Abstract
Conventionally, non-uniformly excited antenna arrays are synthesized by independently determining the excitation amplitude and phase of each single element. Such an approach is considered to be the most expensive and complex design method available. In this paper, the tilling technique is harnessed to synthesize non-uniformly excited antenna arrays. To apply this technique, the array elements are first divided into different subarray shapes, such as rectangles or squares known as tiles. The use of rectangular tile blocks instead of a single element architecture greatly simplifies the array design process and reduces array complexity. Next, the problem concerned with synthesizing sub-arrays comprising rectangular tile blocks is formulated and solved by using horizontal and vertical orientations of tiles having different shapes and sizes, and their larger integer expansions. The third approach to tiled design is a mixture of both previous tile architectures. A genetic algorithm is used to design such tiled arrays offering optimum sidelobe levels, beam width, directivity and taper efficiency. Simulation results demonstrated the effectiveness of the proposed tiled arrays. -
Searching for an Efficient System of Equations Defining the AES Sbox for the QUBO Problem
Abstract
The time complexity of solving the QUBO problem depends mainly on the number of logical variables in the problem. This paper focuses mainly on finding a system of equations that uniquely defines the Sbox of the AES cipher and simultaneously allows us to obtain the smallest known optimization problem in the QUBO form for the algebraic attack on the AES cipher. A novel method of searching for an efficient system of equations using linear-feedback shift registers has been presented in order to perform that task efficiently. Transformation of the AES cipher to the QUBO problem, using the identified efficient system, is presented in this paper as well. This method allows us to reduce the target QUBO problem for AES-128 by almost 500 logical variables, compared to our previous results, and allows us to perform the algebraic attack using quantum annealing four times faster.
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Deep Learning-Powered Beamforming for 5G Massive MIMO Systems
Abstract
In this study, a ResNeSt-based deep learning approach to beamforming for 5G massive multiple-input multiple-output (MIMO) systems is presented. The ResNeSt-based deep learning method is harnessed to simplify and optimize the beamforming process, consequently improving performance and efficiency of 5G and beyond communication networks. A study of beamforming capabilities has revealed potential to maximize channel capacity while minimizing interference, thus eliminating inherent limitations of the traditional methods. The proposed model shows superior adaptability to dynamic channel conditions and outperforms traditional techniques across various interference scenarios.
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Designing Smart Antennas Using Machine Learning Algorithms
Abstract
Smart antenna technologies improve spectral efficiency, security, energy efficiency, and overall service quality in cellular networks by utilizing signal processing algorithms that provide radiation beams to users while producing nulls for interferers. In this paper, the performance of such ML solutions as the support vector machine (SVM) algorithm, the artificial neural network (ANN), the ensemble algorithm (EA), and the decision tree (DT) algorithm used for forming the beam of smart antennas are compared. A smart antenna array made up of 10 half-wave dipoles is considered. The ANN method is better than the remaining approaches when it comes to achieving beam and null directions, whereas EA offers better performance in terms of reducing the side lobe level (SLL). The maximum SLL is achieved using EA for all the user directions. The performance of the ANN algorithm in terms of forming the beam of a smart antenna is also compared with that of the variable-step size adaptive algorithm.
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Pilot Agent-Driven Wireless Acoustic Sensor Network for Uninterrupted Data Transmission
Abstract
Wireless acoustic sensor networks (WASN) usually demand uninterrupted and reliable data transmissions and an efficient path from the source nodes to the destination nodes, thus ensuring reliable delivery of sensitive or critical data with the use of multipath routing protocols. This paper presents a novel agent-driven WASN relying on a set of static and mobile agents. In the proposed technique, the location address is functioned into the operating node and the destination node. Calculations of the midpoint between the operating and the destination nodes are followed by identifying the shortest path based on a reference axis, using a mobile agent and a location address. Such an approach aims to ensure maximum utilization of the communicating paths. Based on the information concerning partial topology of the network, the destination node computes the weight factor and multiple paths using node distances, energy ratios and efficiencies of specific links. Then, the destination node selects the appropriate path from the multiple paths available, to transmit the data. This article also analyzes the performance of the proposed system with various parameters taken into consideration and shows its efficiency in comparison to other existing techniques.
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Radar Cross-section Reduction of Planar Absorbers Using Resistive FSS Unit Cells
Abstract
This paper demonstrates the feasibility of reducing radar cross-section by employing resistive sheets or rings in the conducting elements of an FSS unit cell. The idea behind the approach in question is to create power-absorbing elements which may help reduce the power reflected from FSS surface. The investigated FSS unit cells have the form of double-closed rings and double-closed-split rings. A carbon paste, serving as the resistive layer, was inserted in various regions within the unit cell. The CST Microwave Studio software was used to obtain the reflection coefficient. Specific dimensions and conductivity of the paste were selected to ensure better performance. Simulation results showed that the reflection coefficient may be reduced by 8 dB, to 14 dB, by using carbon paste with the conventional copper layer.
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Advanced Considerations Concerning Impact of Applied Call Admission Control Mechanisms on Traffic Characteristics in Elastic Optical Network Nodes
Abstract
Over the past few years, a significant increase in network traffic volumes has been observed. The ever growing bandwidth demands mean that a reliable and optimum service level needs to be ensured in communication systems for specific traffic categories. Optimal allocation and use of resources may be achieved through the use of call admission control (CAC) mechanisms implemented in network systems. The resource reservation mechanism and the threshold mechanism are two of the most popular CAC methods. In the reservation mechanisms, a certain number of resources is reserved for selected (predefined) services only. In the case of threshold mechanisms, the number of resources allocated to individual traffic classes depends on the network load. This article discusses the results of simulations verifying the impact of applied CAC mechanisms on the traffic characteristics in elastic optical network (EON) nodes with a Clos structure. Loss probability results obtained with the use of the simulator are presented as well.
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High Gain WAT Antenna for 38 GHz 5G Systems
Abstract
The article presents a high gain WAT microstrip antenna designed for 5G communication systems operating in the 38 GHz band. The antenna concerned has a compact structure with dimensions of 5.16×5.05 mm. Rogers RT5880 laminate with a dielectric coefficient of 2.2 and a thickness of 0.254 mm was used as its substrate. The antenna works at a center frequency of 38 GHz and is characterized by a low reflection coefficient of -29.11 dB, a high energy gain of 7.61 dB and a wide operating band of 1.21 GHz (3.18%). The paper presents an analysis of the simulation results and measurements of the device's electrical parameters and radiation patterns.
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Hierarchical Access Structure-based Scheme with Outsourcing and Revocation Mechanism for Cloud Environment
Abstract
Ciphertext policy attribute-based encryption (CPABE) is one of the efficient implementations of encrypted access control scheme for cloud computing. Though multiple implementations of CPABE exist, there are some issues that need to be addressed, including efficient revocation approach, decryption time, storage cost etc. In this paper, an efficient scheme that incorporates a hierarchical access structure, outsourced decryption, as well as user and attribute revocation is presented. The hierarchical access structure is utilized to encrypt multiple data using one common access structure and makes the encryption process more efficient. The outsourcing server is used to perform partial decryption, so that all heavy computations are performed by this server and less overhead is incurred by the data user. The proposed framework also integrates the evaluation of trustworthiness of data users and service providers to ensure trusted and encrypted access control procedures. The paper also presents an analysis of the time required for performing different operations. Simulation results show that the proposed scheme outperforms the existing approaches.
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The Threat of Optical Transmission Jamming
Abstract
In this paper, we investigate how data transmissions may be affected by various types of optical interference introduced into the fiber on purpose, via a clip-on coupler. The research proved that transmissions may be jammed completely using inexpensive equipment readily available on the market, provided that the attacker has physical access to the fiber optic cable. The most dangerous attacks rely on a typical, slowly modulated communication laser with a rectangular waveform. This study urges further research aimed at counteracting such attacks.
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The New Analytical Model of Free Resources in the Limited Availability Resources
Abstract
The article presents a new analytical model for determining the probability of availability of a certain amount of well-defined free resources (e.g. a link) in a group of dedicated resources (e.g. a group of links) jointly serving a mixture of different classes of multiservice traffic. The presented method can be used to model access to resources in data centres, in particular in the software-defined networks, assuming -- for reliability reasons -- that the user should have access to a certain minimum number of specific separated resources. The proposed analytical model was verified by appropriate simulation experiments, which confirmed the satisfactory accuracy of the results obtained.
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Monitoring, Management, and Analysis of Security Aspects of IaaS Environments
Abstract
Many companies or institutions either already have placed their resources in or plan to move them to the cloud. They do so for security reasons and are weary of the fact that by relying on cloud-based resources, they do not have to bear such extensive infrastructure-related costs. However, continuous technology advancement results not only in benefits, but also in disadvantages. The latter include the growing risk associated with IT security, forcing the individual actors to implement monitoring measures and to respond to numerous threats.
This work focuses on creating a small infrastructure setup using the publicly available Google Cloud Platform which, thanks to the monitoring systems implemented thereon, allows to rapidly respond to hardware and software faults, including those caused by external factors, such as attacks on specific components. This project may also be customized to satisfy individual needs, depending on the cloud service provider selected. The work uses public cloud provider tools as well as open-source systems available for everyone, both in the cloud and in the on-prem environment. The paper deals also with the concept of a proprietary intrusion detection system. -
A Brief History of UTC Leap Second
Abstract
Since 1972, a leap second has been added, approximately once a year, into UTC, the world's atomic time scale used for civilian purposes, to keep it in phase with the Earth's rotation. Leap seconds ensure that the Sun remains over the Greenwich meridian at noon, with the accuracy of approximately 1 s. The issue of adding the leap second has been debated since 2000 by different working groups of various international organizations, especially ITU-R WP 7A. The main question remains whether the need for the leap second still exists, as its introduction is associated with numerous technical inconveniences. An overwhelming opinion that prevails in those groups is that it would be more beneficial to let the atomic time run its course and accept that the world's civilian time scale is bound to slowly diverge from the rotation of the Earth. The National Institute of Telecommunications has become, in recent years, one of the leaders of this process. This article provides a brief history of the current UTC-related practices and outlines various potential solutions to the problem.
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A Problem of Detecting Stops While Tracking Moving Objects Under the Stream Processing Regime
Abstract
The tracking of moving objects with the use of GPS/GNSS or other techniques is relied upon in numerous applications, from health monitoring and physical activity support, to social investigations to detection of fraud in transportation. While monitoring movement, a common subtask consists in determining the object's moving periods, and its immobility periods. In this paper, we isolate the mathematical problem of automatic detection of a stop of tracking objects under the stream processing regime (ideal data processing algorithm regime) in which one is allowed to use only a constant amount of memory, while the stream of GNSS positions of the tracked object increases in size. We propose an approximation scheme of the stop detection problem based on the fuzziness in the approximation of noise level related to the position reported by GNSS. We provide a solving algorithm that determines some upper bounds for the problem's complexity. We also provide an experimental illustration of the problem at hand.
