Thokozani Shongwe

University of Johannesburg | uj · Department of Electrical and Electronic Engineering

Channel bandwidth-limited high-speed links or interfaces make circuit solutions not efficient. Both recent and subsequent links (SerDes-Serializer/Deserializer) design demand efficient and effective coupling between future circuit design, communication, and optimization. The challenges vary and new solutions are needed. In this article, an analytic...

The ever-growing modern smart grid with more distributed energy resources is providing efficient energy supply while facing several challenges that include harmonics induced among many. Previous and present literature shows that various machine and deep learning models are superior and accurate as compared to the traditional and conventional signal...

A spherical antenna array (SAA) is an array-designed arrangement capable of scanning in almost all the radiation sphere with constant directivity. It finds recent applications in aerospace, spacecraft, vehicular and satellite communications. Therefore, estimation of the direction-of-arrival (DoA) of electromagnetic (EM) waves that impinge on an SAA...

With the recent advancement in baseband integrated circuits and radio frequency (RF) technology, there is a strong demand to minimize the size of array-based microwave systems. However, array aperture miniaturization often leads to strong mutual coupling in the arrays. To date, mitigating and/or compensating the mutual coupling (nonlinear) effect r...

p> Cryptocurrencies acquire user confidence by making the whole creation and transaction history transparent to the public. In exchange, the transaction history accurately captures the complete range of user activities related to cryptocurrencies. In this paper, the use of data mining methods in Bitcoin transactions is analyzed and summarized. Cryp...

This paper proposes Power Line Communication (PLC) schemes that improve the data rate of PLC systems while combating impairments resulting from frequency disturbances like impulse noise. Firstly, a modified subcarrier selection technique that can be employed to transmit one or more M-ary Phase-Shift Keying (MPSK) or M-ary Quadrature Amplitude Modul...

Cryptocurrencies acquire user confidence by making the whole creation and transaction history transparent to the public. In exchange, the transaction history accurately captures the complete range of user activities related to cryptocurrencies. It is thought to be one of the safest and simplest payment methods that may be employed in the future. Th...

Citation: Henry, A.; Gautam, S.; Khanna, S.; Rabie, K.; Shongwe, T.; Bhattacharya, P.; Sharma, B.; Chowdhury, S. Composition of Hybrid Deep Learning Model and Feature Optimization for Intrusion Detection System. Sensors 2023, 23, 890. https://doi.org/10.3390/ s23020890 Academic Editors: Ali Ismail Awad, Abstract: Recently, with the massive growth o...

Aperture efficiency determines the percentage of radiation power incident upon the antenna available at the feed-point. Because the geometry of re ector is xed, the behavior is primarily a function of the feed. The feed line that connects (transmit/receive) RF to the feed becomes an integral part of the system, so achieving maximum aperture efficie...

p> Cryptocurrencies acquire user confidence by making the whole creation and transaction history transparent to the public. In exchange, the transaction history accurately captures the complete range of user activities related to cryptocurrencies. In this paper, the use of data mining methods in Bitcoin transactions is analyzed and summarized. Cryp...

p> Cryptocurrencies acquire user confidence by making the whole creation and transaction history transparent to the public. In exchange, the transaction history accurately captures the complete range of user activities related to cryptocurrencies. In this paper, the use of data mining methods in Bitcoin transactions is analyzed and summarized. Cryp...

Prediction of electrical power harmonics promotes development and provision of clean power supply. However, the elevated frequency combined with noise of harmonics make precise forecasting challenging and demanding. Due to the stochastic nature of harmonics occurrence and the challenge of attaining a dependable, and efficient working model, to this...

Spherical antenna array (SAA) exhibits the ability to receive electromagnetic (EM) waves with the same signal strength, regardless of the direction-of-arrival (DoA), angle-of-arrival, and polarization. Hence, estimating the DoA of EM signals that impinge on SAA in the presence of mutual coupling requires research consideration. In this paper, a sub...

Spherical antenna array (SAA) is a configuration that scans almost all the radiation sphere with constant directivity. It finds applications in spacecraft and satellite communication. Multiple signal classification (MUSIC) is a widely used multiple source direction-of-arrival (DoA) estimation method because of its low complexity implementation in p...

In optimization of wireless networks, path loss prediction is of great importance for adequate planning and budgeting in wireless communications. For efficient and reliable communications in the tropics, determination or estimation of channel parameters becomes important. Research for this article employed different machine learning techniques—AdaB...

The integration of solar photovoltaic (PV) systems and utility grids has gradually gained significant interest in improving the sustainability of clean power supply for society. However, power quality remains a challenge due to partial shading conditions and harmonics. To overcome these drawbacks, a flexible radial movement optimization based on a...

The recent combination of ambient backscatter communication (ABC) with non-orthogonal multiple access (NOMA) has shown great potential for connecting large-scale Internet of Things (IoT) in future unmanned aerial vehicle (UAV) networks. The basic idea of ABC is to provide battery-free transmission by harvesting the energy of existing RF signals of...

Unplanned power plant failures have been seen to be a major cause of power shortages, and thus customer power cuts, in the South African power grid. These failures are measured as the unplanned capability loss factor (UCLF). The study of South Africa’s UCLF is almost non-existent. Parameters that affect the future UCLF are, thus, still not well und...

Direction-of-arrival (DoA) estimation of electromagnetic (EM) waves impinging on a spherical antenna array in short time windows is examined in this paper. Reflected EM signals due to non-line-of-sight propagation measured with a spherical antenna array can be coherent and/or highly correlated in a snapshot. This makes spectral-based methods ineffi...

In recent years, the use of solar photovoltaic (PV) technologies for generating electricity has gained much popularity due to their efficiency, cost-effectiveness, reliability and the need to reduce carbon emissions and air pollution levels around the world in order to control and limit global climate change. Drone-based inspection of Solar Plants...

Failure of element (s) in antenna arrays impair (s) symmetry and lead to unwanted distorted radiation pattern. The replacement of defective elements in aircraft antennas is a solution to the problem, but it remains a critical problem in space stations. In this paper, an antenna array diagnosis technique based on multivalued neural network (mNN) inv...

To obtain an antenna array with isotropic radiation, spherical antenna array (SAA) is the right array configuration. The challenges of locating signals transmitted within the proximity of antenna array have been investigated considerably in the literature. However, near-field (NF) source localization of signals has hitherto not been investigated ef...

This paper proposes a reduced-complexity detection technique for a radio frequency mirror media-based space-time block coded spatial modulation (MB-STBC-SM) over a slow, frequency-flat Rayleigh fading channel, which reduces the computational complexity of the MB-STBC-SM maximum-likelihood (ML) detector. Furthermore, three different mirror activatio...

A spherical antenna array (SAA) is the configuration of choice in obtaining an antenna array with isotropic characteristics. An SAA has the capacity to receive an electromagnetic wave (EM) with equal intensity irrespective of the direction-of-arrival (DoA) and polarization. Therefore, the DoA estimation of electromagnetic (EM) waves impinging on an...

To sustain communication reliability and use the harvested energy effectively, it is crucial to consider energy sharing between energy harvesting tags (EHT) in a multiple access network, which are basic building blocks for the internet of things (IoT) applications. This technique also achieves higher throughput compared with the non-cooperative str...

The South African power distribution network is characterized by long power distribution lines with low short circuit capacity, and when distributed generation is introduced to these lines, voltage magnitudes are severely impacted. The existing voltage regulation methods of the on-load tap changer and step voltage regulator cannot successfully regu...

The on-load tap changer is critical for voltage regulation, however, its voltage regulation philosophy is suitable for one-directional power flow power systems. Since distributed generators introduce bidirectional power flow, the conventional operation of the on-load tap changer will be highly impacted, resulting in high voltage magnitudes that exc...

The Integrated Energy Plan (IEP) was designed to consider South Africa's energy needs from 2015 to 2050, as a guide for energy structural savings and the development of energy policy. The main aim of the Department of Energy is to ensure the security of energy supply. The current energy situation in the country has its gains and challenges. With th...

In digital transmission systems that involve pulse amplitude modulation (PAM), channel coding is useful for spectral shaping by concentrating the frequency energy of the transmitted information towards a predetermined range of the frequency spectrum, or making it have low power content at such frequencies, so as to suit the frequency characteristic...

With a view to adapting information signals to suit the frequency characteristics of digital transmission channels, it is pertinent to design channel coding schemes that can exhibit spectral shaping capabilities after being processed with a suitable modulation technique. This involves concentrating the frequency energy of the coded and modulated in...

In this paper, we investigate the performance of the discrete Hartley transform (DHT) hybrid Power Line Communication - Visible Light Communication (PLC-VLC) system based on asymmetrically clipped optical - orthogonal frequency division multiplexing (ACO-OFDM) in impulsive noise, when the Perfect Nulling technique is utilized to analyze the combati...

This paper presents low-complexity detectors for space-time block coded spatial modulation with cyclic structured (STBC-CSM) codeword over a quasi-static frequency-flat Rayleigh fading channel. Two low-complexity detectors are proposed, which reduce the computational complexity of the STBC-CSM maximum-likelihood (ML) detector and demonstrate near-M...

Noise is generated on the indoor Narrowband Power Line Communication channel by the uncoordinated activities of several electrical devices connected to the power line networks and by radiated environmental disturbances. There is a need to overcome these noise and channel impairments for reliable communication to be achieved. Statistical channel mod...

Ghana currently has no future energy strategic plan or framework for its generation system apart from the Energy Policy developed by the Energy Commission (EC). The EC based its research on the year 2000 parameters and estimated the energy system up to 2020, which cannot entirely address the current challenges facing the energy sector. The main obj...

Recently, the awareness of the severe consequences of greenhouse gases on the environment has escalated. This has encouraged the world to reduce the usage of fossil fuels for power generation and increase the use of cleaner sources, such as solar energy and wind energy. However, the conventional power system itself was designed as a passive power s...

Media-based space-time block coded spatial modulation (MBSTBC-SM) combines the advantages of media-based modulation (MBM) and STBC-SM. Meanwhile, labelling diversity (LD) has been applied to STBC-SM and improve the error performance. Hence, this paper proposes the application of LD to MBSTBC-SM in the form of MBSTBC-SM-LD over a fast, frequency-fla...

To fully deploy the next generation network which is in compliance with the fourth industrial revolution (4IR), there is a need to integrate wireless technologies. This approach develops not just a hybrid network model, but a symbiotic architecture that is secured, reliable, scalable, intelligent in decision making with cross-layer capability to ha...

Integrating cognitive radio into the current power grid is designed to enable smart communication and decisions within the grid. Communication within the grid is not feasible without channel(s) and most studies have emphasized the use of cellular spectrum. This study proposes a strategy that enables the use of television white space (TVWS) within t...

Integrating cognitive radio into the current power grid is designed to enable smart communication and decisions within the grid. Communication within the grid is not feasible without channel(s) and most studies have emphasized the use of cellular spectrum. This study proposes a strategy that enables the use of television white space (TVWS) within t...

A trellis coded 4-ary Pulse Amplitude Modulation (4-PAM) is presented, where the encoding algorithm is derived from Distance Preserving Mapping (DPM) algorithm. In this work, we modify the DPM algorithm for 4-PAM and obtain a new construction for mapping binary sequences to permutation sequences, where the permutation sequences are obtained by perm...

The technology which utilises the power line as a medium for transferring information known as powerline communication (PLC) has been in existence for over a hundred years. It is beneficial because it avoids new installation since it uses the present installation for electrical power to transmit data. However, transmission of data signals through a...

Abstract—Power line communications (PLC) and visiblelight communications (VLC) are two emerging communi-cation technologies which have several similarities. Amongthem, the advantage related to cost effectiveness is consideredas strong research motivation. These two technologies arealso characterized by the fact that each one of them barelyform a co...

An impulse noise detection scheme employing machine learning (ML) algorithm in Orthogonal Frequency Division Multiplexing (OFDM) is investigated. Four powerful ML’s multi-classifiers (ensemble) algorithms (Boosting (Bos), Bagging (Bag), Stacking (Stack) and Random Forest (RF)) were used at the receiver side of the OFDM system to detect if the recei...

In this a paper, we propose a simplistic channel model for cascaded PLC-VLC system which highlights the noise scenario in such hybrid systems. The model utilises previously proposed channel transfer functions of both PLC and VLC channels and highlights the effects of the LED supply in the system. The noise scenario implemented on the model is based...

The analysis of hybrid phase shift keying-color shift keying (MPSK-CSK) systems under the additive white Gaussian noise model is presented. MPSK-CSK systems are formed by mapping phase shift keying symbols to color shift keying using hue-saturation-value color space. Analytical expressions of bit error rate are given for M = 2, 4, 8 and 16, to vali...