No. 3 (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:
2023-09-29
ARTICLES FROM THIS ISSUE
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Coverage Improvements for Sub-Terahertz Systems Under Shadowing Conditions
Abstract
Radio propagation in the millimeter wave and sub-terahertz domain is heavily affected by shadowing conditions. The communication link is blocked without any additional technical means being used. Coverage improvements can be provided by using reflectors, RIS arrays, and repeaters to direct radio waves around corners or obstacles. These concepts show different performance and complexity levels affecting their network deployment. This paper investigates the achievable radio range or the received power to compare specific deployment concepts under realistic propagation conditions. Overall, the repeater solution provides either the largest radio range or the lowest necessary total transmit power compared to reflectors or RIS arrays and, thereby, is the most sustainable approach. A RIS array requires an additional centralized signal processing capacity for calculating optimized RIS settings and results in the highest level of network deployment complexity.
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Comparative Analysis of NOMA and OMA Schemes: GSVD-based NOMA Systems and the Role of Mobile Edge Computing
Abstract
This paper presents a comprehensive study that examines the fundamental concept of the non-orthogonal multiple access (NOMA) scheme and provides its detailed comparison with the orthogonal multiple access (OMA) technique. Furthermore, the paper explores the application of the generalized singular value decomposition (GSVD) method in conjunction with NOMA, accompanied by a detailed review of GSVD-based NOMA systems. This study also introduces the concept of mobile edge computing (MEC) and extensively discusses its key parameters. Furthermore, a comprehensive analysis of NOMA MEC is presented, shedding light on its potential advantages and challenges. The aims of this study are to provide a comprehensive understanding of the aforementioned topics and contribute to the advancement of MIMO-NOMA systems.
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Performance Comparison of Several Algorithms for Localization of Wideband Sources
Abstract
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.
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Implementation of a 4G/5G Base Station Using the srsRAN Software and the USRP Software Radio Module
Abstract
This article presents the potential applications and scenarios for the implementation of a software-defined radio (SDR) module operating as a base station in 4G/5G networks. The paper presents test configurations of the srsRAN software environment in conjunction with various types of programmable radio modules. Then, the key performance metrics of the mobile telephony system and potential problems that may be encountered while implementing hardware and software layers are presented.
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An Efficient Cooperative Spectrum Sensing Method Using Renyi Entropy Weighted Optimal Likelihood Ratio for CRN
Abstract
The main concept behind employing cognitive radio is to enable secondary users (SUs) or unlicensed users to utilize the available spectrum. Spectrum sensing methods detect the existence of primary users (PUs) and have become the main topic of research in the CRN industry and in academia. This paper proposes a new framework based on the Adam gradient descent (Adam GD) algorithm to develop a spectrum sensing mechanism used in CRNs and detecting the availability of free channels. The signal's components are extracted from the received signal and the spectrum is searched for availability which is detected through a fusion center using the proposed algorithm. The proposed Adam GD algorithm attains the maximum detection probability rate and the minimum false alarm probability of 0.71 and 0.39, respectively, for a Rayleigh channel.
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Location-based Power Control Mechanism for D2D Communication Underlaying a Cellular System
Abstract
The paper presents a location-based approach to controlling the power of device-to-device (D2D) underlay of a frequency reuse-1 cellular system. The system allows for direct communication to share uplink resources with cellular users. As a result, both D2D and cellular users are experiencing additional interferences in the system. By controlling the output power of the devices, these interferences can be mitigated and the performance of the network can be improved in terms of better spectral and energy efficiency. The proposed location-based target signal-to-interference ratio power control scheme for D2D communications utilizes information about users' locations to estimate the interference level experienced by the receiver of the direct link. Based on this estimation, an appropriate transmit power can be determined. The performance of the proposed power control solution is investigated via system level simulations.
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A Cross-layer Method for Scheduling and Routing Real-time Traffic Flow in Industrial IoT
Abstract
In the Industrial Internet of Things, a wide variety of sensors are distributed all over the environment to monitor data collection, thereby allowing industrial processes to be monitored more efficiently. One of the fundamental goals of IIoT is to provide the highest level of reliability while simultaneously increasing network lifetime, reducing power consumption, and preventing delays. 6TiSCH is a popular communication standard relied upon in IIoT. The aim of the present study is to propose an inter-layer method that simultaneously considers network scheduling and routing processes based on TSCH and RPL approaches in multi-sink environments. The proposed method is intended to address the limitations of IIoT and meet the requirements of field-specific applications.
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Characterization of a Split Circle Element for Microstrip Reflectarrays
Abstract
A split circular element is proposed as a unit cell for reflectarray antennas. The unit cell is derived from a circle divided into four equal sectors. The radius of two oppositely located sectors is then scaled by a certain factor to form the proposed shape. The CST Microwave Studio Suite software simulator was used to investigate the performance of the proposed unit cell, which was evaluated using Floquet port excitation. The designed element's reflection phase range was compared to that of a conventional circular patch. Four scenarios of varied substrate characteristics are investigated for the antenna to establish the best performance parameters. The simulations showed that a basic substrate with a thickness of 0.16 mm and a dielectric constant of 3.2, backed by a 3 mm foam with a dielectric constant of 1.05 and a scaling factor of 0.72 offers a wide phase range of 601.3°. The obtained phase slope is 76.37°/mm or 134°/GHz.
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Design and Analysis of a Low-profile Microstrip Antenna for 5G Applications using AI-based PSO Approach
Abstract
Microstrip antennas are high gain aerials for low-profile wireless applications working with frequencies over 100 MHz. This paper presents a study and design of a low cost slotted-type microstrip patch antenna that can be used in 5G millimeter wave applications. This research focuses on the effect of ground slots and patch slots which, in turn, affect different antenna parameters, such as return loss, VSWR, gain, radiation pattern, and axial ratio. The working frequency range varies from 24 to 28 GHz, thus falling within 5G specifications. A subset of artificial intelligence (AI) known as particle swarm optimization (PSO) is used to approximatively solve issues involving maximization and minimization of numerical values, being highly challenging or even impossible to solve in a precise manner. Here, we have designed and analyzed a low-profile printed microstrip antenna for 5G applications using the AI-based PSO approach. The novelty of the research is mainly in the design approach, compactness of size and antenna applicability. The antenna was simulated with the use of HFSS simulation software.
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Utilization of Reconfigurable Intelligent Surfaces with Context Information - Use Cases
Abstract
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.
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Minimized Group Delay FIR Low Pass Filter Design Using Modified Differential Search Algorithm
Abstract
Designing a finite impulse response (FIR) filter with minimal group delay has proven to be a difficult task. Many research studies have focused on reducing pass band and stop band ripples in FIR filter design, often overlooking the optimization of group delay. While some works have considered group delay reduction, their approaches were not optimal. Consequently, the achievement of an optimal design for a filter with a low group delay value still remains a challenge. In this work, a modified differential search optimization algorithm has been used for the purpose of designing a minimal group delay FIR filter. The results obtained have been compared with the classical techniques and they turned out to be promising.
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Performance Evaluation of a Zone-based Three-level Heterogeneous Clustering Protocol for WSNs
Abstract
This paper proposes a zone-based three-level heterogeneous clustering protocol (ZB-TLHCP) for heterogeneous WSNs. In ZB-TLHCP, the sensor field/region is divided into zones where super, advance, and normal nodes are deployed uniformly and randomly. The performance of the proposed ZB-TLHCP system is compared with that of zonal-stable election protocol (Z-SEP), distributed energy efficient clustering (DEEC), and threshold-based DEEC (TDEEC) protocol by varying the number of super and advance nodes, their energy levels for the fixed sensor field, and the total number of nodes. Matlab simulation results revealed that the proposed ZB-TLHCP solution performed better than Z-SEP, DEEC, and TDEEC protocols, as it increased the instability period, prolonged the network's lifetime, and achieved higher throughput values.
