Utilization of Reconfigurable Intelligent Surfaces with Context Information: Use Cases, Journal of Telecommunications and Information Technology, 2023, nr 3

Utilization of reconfigurable intelligent surfaces is a topic that is very interesting in the context of complex radio environments, especially those used in dense urban areas. By relying on simple solutions to control the angle of reflection of the signal from the surface, different effects may be achieved in radio communication systems. Maximization or minimization of the received power at specific locations near the reflecting surface is the most important effect. This phenomenon allows to: receive a signal at a location at which it could not be received previously, detect spectrum occupancy at a place where the sensor could not perform a correct detection, or minimize interference affecting a specific receiver. In this paper, all three concepts are presented and a simple ray tracing simulation is used to show the potential profits attainable in each of the scenarios. Additionally, a scenario was analyzed in which several of the aforementioned situations are combined

Single Linkage Weighted Steepest Gradient Adaboost Cluster-Based D2D in 5G Networks, Journal of Telecommunications and Information Technology, 2023, nr 1

Efficiency of data transmissions with minimum latency levels and better resource utilization is a challenging issue in 5 G device-to-device (D 2D) environments. A novel technique referred to as single linkage steepest gradient gentle AdaBoost cluster-based device (SLSGAC) is introduced to improve device-to-device communications with minimum latency. The proposed technique uses the ensemble clustering approach to group mobile devices by constructing a set of weak clusters, based on the Minkowski single linkage clustering technique. In the weak clustering process, residual energy, bandwidth and SINR are estimated, and mobile devices are grouped based on the Minkowski distance measure. Results of the weak clustering process are combined to provide the final ensemble’s clustering output by applying the steepest gradient function to minimize the error rate. For each cluster, a head is selected from among the group members to improve the data transmission rate and minimize latency. Simulations are conducted comparing the proposed technique with the existing methods based on such metrics as energy efficiency, data delivery ratio, packet loss rate, throughput and latency

Improving Quality of Watermarked Medical Images Using Symmetric Dilated Convolution Neural Networks, Journal of Telecommunications and Information Technology, 2023, nr 2

Rapid development of online medical technologies raises questions about the security of the patient’s medical data.When patient records are encrypted and labeled with a watermark, they may be exchanged securely online. In order to avoid geometrical attacks aiming to steal the information, image quality must be maintained and patient data must be appropriately extracted from the encoded image. To ensure that watermarked images are more resistant to attacks (e.g. additive noise or geometric attacks), different watermarking methods have been invented in the past. Additive noise causes visual distortion and render the potentially harmful diseases more difficult to diagnose and analyze. Consequently, denoising is an important pre-processing method for obtaining superior outcomes in terms of clarity and noise reduction and allows to improve the quality of damaged medical images. Therefore, various publications have been studied to understand the denoising methods used to improve image quality. The findings indicate that deep learning and neural networks have recently contributed considerably to the advancement of image processing techniques. Consequently, a system has been created that makes use of machine learning to enhance the quality of damaged images and to facilitate the process of identifying specific diseases. Images, damaged in the course of an assault, are denoised using the suggested technique relying on a symmetric dilated convolution neural network. This improves the system’s resilience and establishes a secure environment for the exchange of data while maintaining secrecy

Design of a Fractional Order Low-pass Filter Using a Differential Voltage Current Conveyor, Journal of Telecommunications and Information Technology, 2023, nr 2

In this paper, an active implementation of a differential voltage current conveyor (DVCC) based on a low-pass filter operating in the fractional order domain is presented. The transfer function for a fractional order system is dependent on the rational approximation of sα. Different methods used for calculating the rational approximation, including Carlson, Elkhazalil, and curve fitting, are evaluated here. Finally, to validate the theoretical results, a fractional order Butterworth filter is simulated in the Pspice environment using the 0.5 micrometer CMOS technology with an R-C network-based fractional order capacitor. Additionally, using the Monte Carlo analysis, the impact of current and voltage faults on DVCC response is investigated. It has been inferred that realization with a wider bandwidth is possible

Beam Pattern Optimization Via Unequal Ascending Clusters, Journal of Telecommunications and Information Technology, 2023, nr 1

In this paper, two different architectures based on completely and sectionally clustered arrays are proposed to improve the array patterns. In the wholly clustered arrays, all elements of the ordinary array are divided into multiple unequal ascending clusters. In the sectionally clustered arrays, two types of architectures are proposed by dividing a part of the array into clusters based on the position of specific elements. In the first architecture of sectionally clustered arrays, only those elements that are located on the sides of the array are grouped into unequal ascending clusters, and other elements located in the center are left as individual and unoptimized items (i.e. uniform excitation). In the second architecture, only some of the elements close the center are grouped into unequal ascending clusters, and the side elements were left individually and without optimization. The research proves that the sectionally clustered architecture has many advantages compared to the completely clustered structure, in terms of the complexity of the solution. Simulation results show that PSLL in the side clustered array can be reduced to more than −28 dB for an array of 40 elements. The PSLL was −17 dB in the case of a centrally clustered array, whereas the complexity percentage in the wholly clustered array method was 12 .5 %, while the same parameter for the partially clustered array method equaled 10%

Energy Consumption in Wireless Systems Equipped with RES, UAVs, and IRSs, Journal of Telecommunications and Information Technology, 2023, nr 2

This paper investigates energy budget characteristics of mobile base stations (BSs) having the form of unmanned aerial vehicles (UAVs) equipped with radio frequency (RF) transceivers, intelligent reconfigurable surfaces (IRSs), and renewable energy sources (RES). The results obtained highlight the benefits and challenges related to using the aforementioned mobile BS, from the energy-related point of view. The specific cases researched involved two types of UAV devices, i.e. multirotor and fixed-wing (airplane-like) aircraft

Jamming Signal Cancellation by Channel Inversion Power Control for Preserving Covert Communications, Journal of Telecommunications and Information Technology, 2023, nr 2

Uninformed jammers are used to facilitate covert communications between a transmitter and an intended receiver under the surveillance of a warden. In reality, the signals the uniformed jammer emits to make the warden’s decision uncertain have inadvertently interfered with the detection of the intended receiver. In this paper, we apply truncated channel inversion power control (TCIPC) to both the transmitter and the uninformed jammer. The TCIPC scheme used on the uninformed jammer may help the intended receiver remove jamming signals using the successive interference cancellation (SIC) technique. Under the assumption that the warden knows the channel coefficient between two intended transceivers and achieves the optimal detection power threshold, we form the optimization problem to maximize the effective transmission rate (ETR) under covertness and decoding constraints. With the aim of enhancing covertness-related performance, we achieve the optimal power control parameters and determine system parameter-related constraints required for the existence of these solutions. According to the simulations, the use of the TCIPC scheme on the uninformed jammer significantly improves covertness-related performance in comparison to that of random power control (RPC) and constant power control (CPC) schemes. In addition, simulation results show that, for the TCIPC scheme: 1) the maximum ETR tends to converge as the transmitter’s or the uninformed jammer’s maximum transmit power increases, and 2) there exists an optimal value of the transmitter’s predetermined transmission rate to achieve the optimal performance

An Overview of Mobility Management Mechanisms and the Related Challenges in 5G Networks and Beyond, Journal of Telecommunications and Information Technology, 2023, nr 2

Ensuring a seamless connection with various types of mobile user equipment (UE) items is one of the more significant challenges facing different generations of wireless systems. However, enabling the high-band spectrum – such as the millimeter wave (mmWave) band – is also one of the important factors of 5G networks, as it enables them to deal with increasing demand and ensures high coverage. Therefore, the deployment of new (small) cells with a short range and operating within the mmWave band is required in order to assist the macro cells which are responsible for operating long-range radio connections. The deployment of small cells results in a new network structure, known as heterogeneous networks (HetNets). As a result, the number of passthrough cells using the handover (HO) process will be dramatically increased. Mobility management (MM) in such a massive network will become crucial, especially when it comes to mobile users traveling at very high speeds. Current MM solutions will be ineffective, as they will not be able to provide the required reliability, flexibility, and scalability.Thus, smart algorithms and techniques are required in future networks. Also, machine learning (ML) techniques are perfectly capable of supporting the latest 5G technologies that are expected to deliver high data rates to upcoming use cases and services, such as massive machine type communications (mMTC), enhanced mobile broadband (eMBB), and ultra-reliable low latency communications (uRLLC). This paper aims to review the MM approaches used in 5G HetNets and describes the deployment of AI mechanisms and techniques in ″connected mode″ MM schemes. Furthermore, this paper addresses the related challenges and suggests potential solutions for 5G networks and beyond

Preserving Integrity of Evidence with Blockchain Technology in Cloud Forensics for Immigration Management, Journal of Telecommunications and Information Technology, 2023, nr 1

As the popularity of cloud computing increases, safety concerns are growing as well. Cloud forensics (CF) is a smart adaptation of the digital forensics model that is used for fighting the related offenses. This paper proposes a new forensic method relying on a blockchain network. Here, the log files are accumulated and preserved in the blockchain using different peers. In order to protect the system against illegitimate users, an improved blowfish method is applied. In this particular instance, the system is made up of five distinct components: hypervisor (VMM), IPFS file storage, log ledger, node controller, and smart contract. The suggested approach includes six phases: creation of the log file, key setup and exchange, evidence setup and control, integrity assurance, agreement validation and confidential file release, as well as blockchain-based communication. To ensure efficient exchange of data exchange between the cloud provider and the client, the methodology comprises IPFS. The SSA (FOI-SSA) model, integrated with forensic operations, is used to select the keys in the best possible way. Finally, an analysis is conducted to prove the effectiveness of the proposed FOI-SSA techniqu

Performance Comparison of Several Algorithms for Localization of Wideband Sources, Journal of Telecommunications and Information Technology, 2023, nr 3

In recent years, researchers have tried to estimate the direction-of-arrival (DOA) of wideband sources and several novel techniques have been proposed. In this paper, we compare six algorithms for calculating the DOA of broadband signals, namely coherent subspace signal method (CSSM), two-sided correlation transformation (TCT), incoherent multiple signal classification (IMUSIC), test of orthogonality of frequency subspaces (TOFS), test of orthogonality of projected subspaces (TOPS), and squared TOPS (S-TOPS). The comparison is made through computer simulations for different parameters, such as signal-to-noise ratio (SNR), in order to establish the efficiency and performance of the discussed methods in noisy environments. CSSM and TCT require initial values, but the remaining approaches do not need any preprocessing