Theo Swart

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

The conventional 4B6B run-length limited (RLL) code recommended by the IEEE 802.15.7 standard for visible light communication (VLC) is memory consuming as it must be stored at both the encoder and decoder; additionally, it can only be decoded through maximum likelihood (ML) decoding which is costly in terms of computational complexity. In this pape...

Hepatitis B is a potentially deadly liver infection caused by the hepatitis B virus. It is a serious public health problem globally. Substantial efforts have been made to apply machine learning in detecting the virus. However, the application of model interpretability is limited in the existing literature. Model interpretability makes it easier for...

A method for modeling aggregated heavy Markov bursty Ethernet traffic from different sources is proposed in this paper, particularly that prevailing between gateway services and internet routing devices, with the aim of achieving rate accommodation. In other words, to accommodate different rates while filtering out delays in the queue, to achieve a...

In this paper, a parametric prediction model is proposed for a queuing system driven by the Markov process. The aim of the model is to minimize the packet loss caused by time dependency characterized by the queue tail being too long, resulting in a time-out during the transfer of a large dataset. The proposed technique requires the key parameters i...

The high prevalence of chronic kidney disease (CKD) is a significant public health concern globally. The condition has a high mortality rate, especially in developing countries. CKD often go undetected since there are no obvious early-stage symptoms. Meanwhile, early detection and on-time clinical intervention are necessary to reduce the disease pr...

Considerable effort has been focused on efficient error correction schemes in digital communications where the medium of transmission is unfriendly for information transmission. Also, some of such channels have certain frequency characteristics that should be considered during system designs. Permutation coding (PC) has been reported as being capab...

This paper investigates a new combinatorial construction approach based on cyclic difference packings for the construction of an optical orthogonal code that is suitable as a time spreading sequence for fast frequency hopping optical code division multiple access (OCDM) systems. The proposed construction provides a solution to the electrical decodi...

The internet of things (IoT) and wireless sensor networks (WSNs) are two promising technologies for supporting new services and applications. However, because IoT and WSN entail interaction and transaction of device topology discovery protocols, WSN facing some challenges. Topology discovery (TD) is important for WSN in IoT since sensor nodes (SNs)...

Recent advancements in electronic commerce and communication systems have significantly increased the use of credit cards for both online and regular transactions. However, there has been a steady rise in fraudulent credit card transactions, costing financial companies huge losses every year. The development of effective fraud detection algorithms...

Channel coding provides numerous advantages to digital communications. One of such advantages is error correcting capabilities. This, however, comes at the expense of coding rate, which is a function of the codebook's cardinality |C| or number of coded information bits and the codeword length M. In order to achieve high coding rate, we hereby repor...

The latest research exploits to increase optical channel bandwidth are termed polarization division multiplexing (PDM) and few mode fiber (FMF), which rely upon a complex multiplexed architecture together with customized electro-optic modulated hardware elements, inhibited by cost implications and technical limitations thereof. The research pursued...

The internet of things (IoT) and wireless sensor networks (WSNs) are two promising technologies for supporting new services and applications. However, because IoT and WSN entail interaction and transaction of device topology discovery protocols, WSN is faced with some challenges. Topology discovery (TD) is an important task for WSN in the handling...

Presently, the use of a credit card has become an integral part of contemporary banking and financial system. Predicting potential credit card defaulters or debtors is a crucial business opportunity for financial institutions. For now, some machine learning methods have been applied to achieve this task. However, with the dynamic and imbalanced nat...

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 recent times, several machine learning models have been built to aid in the prediction of diverse diseases and to minimize diagnostic errors made by clinicians. However, since most medical datasets seem to be imbalanced, conventional machine learning algorithms tend to underperform when trained with such data, especially in the prediction of the...

In recent time, several machine learning models have been built to aid in the prediction of diverse diseases and to minimize diagnostic errors made by clinicians. However, since most medical datasets seem to be imbalanced, conventional machine learning algorithms tend to underperform when trained with such data, especially in the prediction of the...

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...

Article Info ABSTRACT Article history: Received Revised Accepted The Internet of Things (IoT) and Wireless Sensor Networks (WSN) are twin promising technologies for supporting new services and applications of the fourth industrial revolution (4IR). However, due to the fact that IoT and WSN entail interaction and transaction of device topology disco...

Article Info ABSTRACT Article history: Received Revised Accepted Presently, the use of a credit card has become an integral part of contemporary banking and financial system. Predicting potential credit card defaulters or debtors is a crucial business opportunity for financial institutions. For Now, some machine learning methods have been applied t...

Article Info ABSTRACT Article history: Received Revised Accepted The internet of things (IoT) and wireless sensor networks (WSNs) are two promising technologies for supporting new services and applications. However, because IoT and WSN entail interaction and transaction of device topology discovery protocols, WSN is faced with some challenges. Topo...

Currently, credit card usage has become a crucial part of modern banking and predicting potential credit card defaulters is a critical business opportunity for financial institutions. Meanwhile, some machine learning methods have been applied to achieve this task. However, with the dynamic and imbalance nature of credit card default datasets, it is...

Currently, credit card usage has become a crucial part of modern banking and predicting potential credit card defaulters is a critical business opportunity for financial institutions. Meanwhile, some machine learning methods have been applied to achieve this task. However, with the dynamic and imbalance nature of credit card default datasets, it is...

In this paper, the construction of binary balanced codes is revisited. Binary balanced codes refer to sets of bipolar codewords where the number of "1"s in each codeword equals that of "0"s. The first algorithm for balancing codes was proposed by Knuth in 1986; however, its redundancy is almost two times larger than that of the full set of balanced...

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...

We present a systematic variable-to-fixed (VF) length scheme encoding binary information sequences into binary balanced sequences. The redundancy of the proposed scheme is larger than the redundancy of the best fixed-to-fixed (FF) length schemes in case of long codes, but it is smaller in case of short codes. The biggest advantage comes from the si...

We investigate a Knuth-like scheme for balancing q-ary codewords, which has the virtue that look-up tables for coding and decoding the prefix are avoided by using precoding and error correction techniques. We show how the scheme can be extended to allow for error correction of single channel errors using a fast decoding algorithm that depends on sy...

We introduce a new construction for the balancing of non-binary sequences that make use of Gray codes for prefix coding. Our construction provides full encoding and decoding of sequences, including the prefix. This construction is based on a generalization of Knuth's parallel balancing approach, which can handle very long information sequences. How...

We present an encoding and decoding scheme for constant weight sequences, that is, given an information sequence, the construction results in a sequence of specific weight within a certain range. The scheme uses a prefix design that is based on Gray codes. Furthermore, by adding redundant symbols we extend the range of weight values for output sequ...

We present an encoding and decoding scheme for constant weight sequences, that is, given an information sequence, the construction results in a sequence of specific weight within a certain range. The scheme uses a prefix design that is based on Gray codes. Furthermore, by adding redundant symbols we extend the range of weight values for output sequ...

We report a new concept involving an adaptive mixture of different sets of permutation codes (PC) in a single DPSK-OFDM modulation scheme. Since this scheme is robust and the algorithms involved are simple, it is a good candidate for implementation for OFDM-based power line communication (PLC) systems. By using a special and easy concept called Ham...

Minimum Hamming distance, dm, has been widely used as the yardstick for the performance of permutation codes (PCs). However, a number of PCs with the same dm and cardinality can have different performances, even if they have the same distance optimality. Since PC is a robust channel coding scheme in power line communications applications, we presen...

We present the construction of interleaving arrays for correcting clusters as well as diffuse bursts of insertion or deletion errors in constrained data. In this construction, a constrained information sequence is systematically encoded by computing a small number of parity checks and inserting markers such that the resulting code word is also cons...

Balancing sequences over a non-binary alphabet is considered, where the algebraic sum of the components (also known as the weight) is equal to some specific value. Various schemes based on Knuth’s simple binary balancing algorithm have been proposed. However, these have mostly assumed that the prefix describing the balancing point in the algorithm...

The recently proposed Pearson codes offer immunity against channel gain and offset mismatch. These codes have very low redundancy, but efficient coding procedures were lacking. In this paper, systematic Pearson coding schemes are presented. The redundancy of these schemes is analyzed for memoryless uniform sources. It is concluded that simple codin...

This chapter discusses the single carrier modulation techniques which have been proposed and used in first generation narrowband PLC systems. It emphasizes the recent insight and research focusing first on frequency/phase shift keying combined with permutation coding. The chapter covers multicarrier modulation which is at the heart of latest narrow...

This second edition of Power Line Communications will show some adjustments in content including new material on PLC for home and industry, PLC for multimedia, PLC for smart grid and PLC for vehicles. Additional chapters include coverage of Channel Characterization, Electromagnetic Compatibility, Coupling, and Digital Transmission Techniques. This...

For the past 15 years since its appearance, Internet of Things (IoT) technology has been leading the planet towards a smart world where all devices and physical objects, referred to as “things”, will be connected via electronic sensors through the Internet. The distribution of medication to patients at a pharmacy in certain regions is still very tr...

It is very critical for solar racers to achieve real time tracking of their solar vehicle during any race. The system is made of real time visualisation of the video feedback of the car from the escort vehicle, the location of the car on the maps as it is racing and its velocity. The real time video feedback of the race could be retrieved from the...

The integration of power line communication (PLC) and visible light communication (VLC) is increasingly receiving a lot of research interest with the advent of (IEEE 1901, ITUT G.9960/61) and IEEE 802.15.7 standards for PLC and VLC respectively. In particular, there is an underlying gain that could be achieved by leveraging the existing ubiquitous...

The integration of power line communication (PLC) and visible light communication (VLC) is increasingly receiving a lot of research interest with the advent of (IEEE 1901, ITUT G.9960/61) and IEEE 802.15.7 standards for PLC and VLC respectively. In particular, there is an underlying gain that could be achieved by leveraging the existing ubiquitous...

Permutation codes are advantageous due to their favourable symbol diversity properties and are applied in flash memories combined with rank modulation. Codebooks traditionally consist of permutations with specific distance properties. A class of permutation codes was presented where a codeword consists of a sequence or concatenation of permutations...

Noise and attenuation, in the form of frequency disturbance , impulsive noise, additive white Gaussian noise (AWGN) and frequency selective fading, are the major setbacks in power line communications (PLC). In order to effectively combat this challenge, we thus report the development and implementation of a specially coded M-ary differential phase...

With a view to improving the capacity of the differential OFDM modulation scheme, specified in the narrowband power line communications (PLC) standards, in combating PLC channel associated noise, we hereby propose a permutation coded modulation scheme, which employs the hybridization of two kinds of DPSK (differential phase shift keying) modulation...

Permutation coding (PC) has been known to be effective in combating power line channel impairments, when used in concatenation with other channel coding schemes like convolutional or Reed Solomon (RS) codes, using FSK, PSK or DPSK as the modulator. We hereby report the development of a modified DPSK modulator, called differential quinary PSK (DQuiP...

Codes are presented that can correct the deletion or the insertion of a predetermined number of adjacent bits greater than or equal to three. This extends the constructions of codes beyond those proposed by Levenshtein fifty years ago to correct one or two adjacent deletions or insertions.

The indoor narrowband power line communication (NB-PLC) suffers from noise impairments, which emanate from several end-user electrical devices connected across the PLC channel. These noise impairments result into burst errors, which consequently lead to data corruption. Therefore, in order to implement robust communication techniques that will thri...

The indoor narrowband power line communication (NB-PLC) suffers from noise impairments, which emanate from several end-user electrical devices connected across the PLC channel. These noise impairments result into burst errors, which consequently lead to data corruption. Therefore, in order to implement robust communication techniques that will thri...

A new class of permutation codes is presented where, instead of considering one permutation as a codeword, codewords consist of a sequence of permutations. The advantage of using permutations, i.e. their favourable symbol diversity properties, is preserved. Additionally, using sequences of permutations as codewords, code rates close to the optimum...

We present a Knuth-like method for balancing q-ary codewords, which is characterized by the absence of a prefix that carries the information of the balancing index. Look-up tables for coding and decoding the prefix are avoided. We also show that this method can be extended to include error correction of single channel errors.

Optimized frequency tones for the power line channel is presented from an experimental scenario. Four sets of frequency tones, grouped according to CENELEC's regulation on frequency use for narrow band power line applications are selected according to their signal-to-noise ratio (SNR) performance. COMBLOCKS, a prototyping hardware was used for the...

A combination of OFDM modulation with fountain and permutation coding for power-line communications is investigated in this paper. A process to identify and mitigate the errors caused by impulse noise and narrow-band interference is proposed. We further present the decoding bit error rate and redundancies introduced by this scheme. Due to its simpl...

Balanced bipolar codes consist of sequences in which the symbols '-1' and '+1' appear equally often. Several generalizations to larger alphabets have been considered in literature. For example, for the q-ary alphabet {-q + 1, -q + 3, ..., q - 1}, known concepts are symbol balancing, i.e., all alphabet symbols appear equally often in each codeword,...

We examine and compare several different classes of "balanced" block codes over q-ary alphabets, namely symbol-balanced (SB) codes, charge-balanced (CB) codes, and polarity-balanced (PB) codes. Known results on the maximum size and asymptotic minimal redundancy of SB and CB codes are reviewed. We then determine the maximum size and asymptotic minim...

A combined code is a code that combines two or more characteristics of other codes. A construction is presented in this paper of permutation codes that are self-synchronizing and able to correct a number of deletion errors per codeword, thus a combined permutation code. Synchronization errors, modelled as deletion(s) and/or insertion(s) of bits or...

For communication schemes employing Frequency Hopping/Multiple Frequency Shift Keying modulation, we present an algorithm for finding good non-binary synchronization sequences, which are permutations, to be used with permutation codes to synchronize/resynchronize data in channels with background noise and interference(frequency jamming/fading). For...