Ling Cheng

Ling Cheng
University of the Witwatersrand | wits · School of Electrical and Information Engineering

PhD

About

155
Publications
21,103
Reads
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861
Citations
Citations since 2016
91 Research Items
747 Citations
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2016201720182019202020212022050100150200
2016201720182019202020212022050100150200
Introduction
Ling Cheng received the degree B. Eng. Electronics and Information (cum laude) from Huazhong University of Science and Technology (HUST) in 1995, M. Ing. (cum laude) and D. Ing. both in Electrical and Electronics from University of Johannesburg (UJ) in 2005, 2011. His research interests are in Telecommunications and Artificial Intelligence. He was promoted to Full Professor at University of the Witwatersrand (Wits) in 2019. He has served as the Vice-chair of IEEE South African Information Theory Chapter since 2018. He has been the principal advisor for over forty full research post-graduate students. He was awarded the Chancellor’s medal in 2005 and 2019, the National Research Foundation rating in 2014, and IEEE ISPLC 2015 best student paper award to his Ph.D. student.
Additional affiliations
September 2019 - present
University of the Witwatersrand
Position
  • Professor (Full)

Publications

Publications (155)
Article
Full-text available
The first-order moment of $(d,k)$ -constrained codes is investigated in this paper. A generalized moment balancing template is proposed to encode a $(d,k)$ sequence into a single insertion or deletion correcting codeword without losing the constraint property. By relocating 0's in moment balancing runs, which appear in a pairwise manner of a $(d,k)...
Article
Full-text available
An M-FSK modulation and time-diversity permutation coding scheme for narrow-band power-line communications combined with the soft-decision technique is investigated in this paper. A process to identify the errors caused by impulse noise and narrow-band interference, and to mitigate the error effects is proposed. We further present a permutation dec...
Conference Paper
Full-text available
In this paper, we present a fast re-synchronization algorithm for permutation coded sequences. The new algorithm combines the dynamic algorithm and a Viterbi-like decoding algorithm for trellis codes. The new algorithm has a polynomial time complexity O(N), where N denotes the length of the sequence. A possible application to M-ary FSK for the CENE...
Conference Paper
Full-text available
In this paper, we present a bidirectional Viterbi decoding algorithm using the Levenshtein distance metric for a regular convolutional encoding system. For a deletion channel, this decoding algorithm can correct an average of 30 deletion errors within a 6000 bit frame, when using an r = 0.67 regular convolutional code; and it can correct an average...
Conference Paper
Full-text available
In this paper, we present a fast synchronization coding scheme, which uses single insertion/deletion error correcting permutation codes. A possible application to M-ary FSK for the CENELEC A band power-line communications (PLC) is considered. Compared to conventional timing recovery schemes, no redundancies for preamble sequences and no processing...
Article
Full-text available
Achieving a sustainable and efficient power systems network and decarbonized environment involves the optimal allocation of multiple distributed energy resource (DERs) unit types and flexible alternating current transmission systems (FACTS) to distribution networks. However, while the most focus is on optimization algorithms and multi-objective tec...
Article
In developing a sustainable and efficient power systems network while reducing carbon footprint, renewable energy (RE)-based Distribution Generation (DG) units are highly recommended. Furthermore, Battery Energy Storage Systems (BESS) and other passive electronic units are adopted to improve grid performance and mitigate the effects of high variabi...
Preprint
With advancements in telecommunications, data transmission over increasingly harsher channels that produce synchronisation errors is inevitable. Coding schemes for such channels are available through techniques such as the Davey-MacKay watermark coding; however, this is limited to memoryless channel estimates. Memory must be accounted for to ensure...
Article
Full-text available
A predictive long short-term memory (LSTM) model developed on a particular water quality dataset will only apply to the dataset and may fail to make an accurate prediction on another dataset. This paper focuses on improving LSTM model tolerance by mitigating discrepancies in model prediction capability that arises when a model is applied to differe...
Article
Full-text available
Channel impairments in powerline communication (PLC) and visible light communication (VLC) technologies are one of the causes of performance degradation in hybrid PLC and VLC (HPV) systems. In this study, we focus on one of the inherent noise types in PLC channels; impulse noise (IN), which is characterised by short bursts of rapidly modified ampli...
Article
Full-text available
Electricity theft is a global problem that negatively affects both utility companies and electricity users. It destabilizes the economic development of utility companies, causes electric hazards and impacts the high cost of energy for users. The development of smart grids plays an important role in electricity theft detection since they generate ma...
Article
Full-text available
Hybrid powerline and visible light communication (HPV) systems offer a cost-effective method of providing high-speed communication in indoor and outdoor environments, for the realisation of internet of things (IoT). However, in the HPV system the powerline communication (PLC) channel is inherently susceptible to impulse noise (IN) due to electrical...
Article
As one technique for autonomous driving, vehicular networks can achieve high efficiency with vehicle-and-infrastructure cooperation, bringing high safety and many value-added services. To achieve higher communication efficiency, many efforts have been done to cope with the resource allocation issues for vehicular networks. Nevertheless, due to the...
Article
Full-text available
Efficient utilization of the spectrum, increased resilience to inter-symbol interference (ISI) and simpler channel equalization are becoming important considerations in the design of wireless communication systems including visible light communication (VLC) systems. In this regard, orthogonal frequency division multiplexing (OFDM) has become a pref...
Article
In this paper, discrete memory channel models of a low-cost, visible light communication (VLC) and a hybrid amplify-and-forward (AF) powerline communication (PLC) and VLC channel are derived using data obtained from an underground mining testbed. The testbed is set up close to the mining face, where blasting occurs. Then, the noise distributions as...
Article
The high peak to average power ratio (PAPR) is the main challenge facing asymmetrically clipped optical (ACO) orthogonal frequency division multiplexing (OFDM). We propose a new hybrid technique that incorporates a modified selective mapping (SLM) and companding called low complexity hybrid selective mapping (LCHSLM) for PAPR mitigation in ACO OFDM...
Article
A multiple access (MA) soft-decision (SD) decoder based on the cost rankings of the channel output matrix, is proposed and applied in an optical wireless communication system in which permutation-based optical codes (POCs) are used. The proposed decoder determines the possible transmitted MA codewords by implementing the Hungarian and Murty’s algor...
Article
In urban Vehicular Ad hoc Networks (VANETs), high mobility of vehicular environment and frequently changed network topology call for a low delay end-to-end routing algorithm. In this paper, we propose a Multi-Agent Reinforcement Learning (MARL) based decentralized routing scheme, where the inherent similarity between the routing problem in VANET an...
Article
Full-text available
For multidimensional data, Space-Filling Curves (SFCs) have been used to improve the execution time of spatial data queries. However, their effect on compression, when used to reorder the uncompressed values, is known to a lesser extent. We investigate the impact of three SFCs on Shuttle Radar Topographic Mission (SRTM) elevation data and Square-Ki...
Article
Full-text available
Errors in realistic channels contain not only substitution errors, but synchronisation errors as well. Moreover, these errors are rarely statistically independent in nature. By extending on the idea of the Fritchman channel model, a novel error category-based methodology for determining channel characteristics is described for memory channels that...
Preprint
Full-text available
The Slepian-Wolf bound on the admissible coding rate forms the most fundamental aspect of distributed source coding. As such, it is necessary to provide a framework with which to model more practical scenarios with respect to the arrangement of nodes in order to make Slepian-Wolf coding more suitable for multi-node Wireless Sensor Networks. This pa...
Article
Full-text available
The error distribution of multicarrier modulation in a narrowband powerline communication (PLC) channel with memory is presented for an underground mining environment. In the environment, the noise in the PLC channel originates from the mains switchboard and a blast control unit, connected to the powerline link. Using the error vectors measured fro...
Article
Free-space-optics-based communication links are an attractive potential solution for solving the last mile challenge but suffer from turbulence-induced fading. This fading causes errors in the received signal. While models exist to predict how turbulence affects the signal, these models often do not account for the channel's memory. Typical fading...
Article
Full-text available
This paper addresses the problem of decoding non-binary low density parity check codes(LDPC) over finite field GF(q) using symbol flipping approach. To achieve low complexity reliable communication, three new algorithms for improving the bit error rate performance of the non-binary LDPC decoder are presented. The first type is the symbol flipping d...
Preprint
Errors in realistic channels contain not only substitution errors, but synchronisation errors as well. Moreover, these errors are rarely statistically independent in nature. By extending on the idea of the Fritchman channel model, a novel error category-based methodology in determining channel characteristics is described for memory channels which...
Article
Full-text available
Distributed generation (DG) units are power generating plants that are very important to the architecture of present power system networks. The primary benefits of the addition of these units are to increase the power supply and improve the power quality of a power grid while considering the investment cost and carbon emission cost. Most studies ha...
Chapter
This work focused on optimizing a Proportional-Integral-Derivative (PID) controller for a single-axis, gimbal-based inertial stabilization system, for a given performance objective. This study compared the suitability and relative performance of two meta-heuristic optimization methods for tuning the PID controller. The methods compared are two natu...
Preprint
Visible Light Communication (VLC) is a current technology which allows data to be transmitted by modulating information onto a light source. It has many advantages over traditional radio frequency communication and up to 10,000 times larger bandwidth. Existing research in visible light communication assumes a synchronised channel, however, this is...
Article
Full-text available
The optimal integration of electrical units, such as distributed generation units, power electronic devices, and electric vehicles, is a significant development of smart grids. This development has effectively transformed the traditional grid system, promising numerous advantages for economic values and autonomous energy source control. In smart gr...
Article
In this paper, soft-decision (SD) decoders of permutation trellis code (PTC) with -ary frequency shift keying are designed using three optimization algorithms and presented in four decoding schemes. In a concatenated code such as PTC, the Viterbi decoder for the outer convolutional code provides maximum likelihood decoding. Hence, the error correct...
Article
Full-text available
Optical communication is an integral part of the modern economy, having all but replaced electronic communication systems. Future growth in bandwidth appears to be on the horizon using structured light, encoding information into the spatial modes of light, and transmitting them down fibre and free-space, the latter crucial for addressing last mile...
Conference Paper
Full-text available
In this paper, we present two low complexity algorithms to decode non-binary LDPC codes. The proposed decoding algorithms update iteratively the hard decision received vector to search for a valid codeword in the vector space of Galois field (GF). The selection criterion for the position of unreliable symbols is based on failed checks and the infor...
Article
Full-text available
The main challenge for hardware implementation of non-binary LDPC decoding is the high computational complexity and large memory requirement. To address this challenge, five new low complexity LDPC decoding algorithms are proposed in this paper. The proposed algorithms are developed specifically towards the low complexity, yet effective, decoding o...
Article
A theory explaining how deep learning works is yet to be developed. Previous work suggests that deep learning performs a coarse graining, similar in spirit to the renormalization group (RG). This idea has been explored in the setting of a local (nearest-neighbor interactions) Ising spin lattice. We extend the discussion to the setting of a long-ran...
Conference Paper
Full-text available
In this study, we focused on the optimal coordinated charging of electric vehicles in a centralized charging model, based on a special multi-objective model. The objective functions are charging cost minimization, load variance minimization, and power loss minimization. The multi-objective problem has been solved by the Whale Optimization Algorithm...
Preprint
Increasing electricity prices in South Africa and the imminent threat of load shedding due to the overloaded power grid has led to a need for Demand Side Management (DSM) devices like smart grids. For smart grids to perform to their peak, their energy management controller (EMC) systems need to be optimized. Current solutions for DSM and optimizati...
Article
Full-text available
Although there has been a rapid development of practical applications, theoretical explanations of deep learning are in their infancy. Deep learning performs a sophisticated coarse graining. Since coarse graining is a key ingredient of the renormalization group (RG), RG may provide a useful theoretical framework directly relevant to deep learning....
Article
Full-text available
In this paper, authors propose a VLC system, whose source of information is assumed to be a power line, and employs a combination of relaying and multiple-input multiple-output (MIMO) techniques. Precisely, the performance of a VLC system, with relay nodes equipped with a MIMO technique called space time block coding (STBC), is investigated. The bi...
Article
With next generation networks driving the confluence of multi-media, broadband, and broadcast services, Cognitive Radio (CR) networks are positioned as a preferred paradigm to address spectrum capacity challenges. CRs address these issues through dynamic spectrum access. However, the main challenges faced by the CR pertain to achieving spectrum eff...
Preprint
Full-text available
Optical communication is an integral part of the modern economy, having all but replaced electronic communication systems. Future growth in bandwidth appears to be on the horizon using structured light, encoding information into the spatial modes of light, and transmitting them down fibre and free-space, the latter crucial for addressing last mile...
Preprint
In this paper, concatenated permutation codewordsare used to improve the code rate of permutation-aided space-time shift keying in multiple input multiple output (MIMO)visible light communication. Soft-decision detection schemes arethen designed for the receiver and compared with the maximumlikelihood (ML) detection method. Bit error rate (BER) res...
Preprint
In this paper, soft-decision decoders of permutation trellis codes (PTC) with M-ary frequency shift-keying are designed using three optimization algorithms and presented in four different decoding schemes. The bit error rate (BER) performance of the schemes are presented in an additive white Gaussian noise (AWGN) and power-line communication (PLC)...
Preprint
The global degradation of water resources is a matter of great concern, especially for the survival of humanity. The effective monitoring and management of existing water resources is necessary to achieve and maintain optimal water quality. The prediction of the quality of water resources will aid in the timely identification of possible problem ar...
Preprint
Full-text available
This paper examines the theory pertaining to lossless compression of correlated sources located at the edge of a network. Importantly, communication between nodes is prohibited. In particular, a method that combines correlated source coding and matrix partitioning is explained. This technique is then made more flexible, by restricting the method to...
Preprint
Full-text available
Surface damage on concrete is important as the damage can affect the structural integrity of the structure. This paper proposes a two-step surface damage detection scheme using Convolutional Neural Network (CNN) and Artificial Neural Network (ANN). The CNN classifies given input images into two categories: positive and negative. The positive catego...
Preprint
Full-text available
Distributed generation (DG) units are power generating plants that are very important to the architecture of present power system networks. The benefit of the addition of these DG units is to increase the power supply to a network. However, the installation of these DG units can cause an adverse effect if not properly allocated and/or sized. Theref...
Preprint
A theory explaining how deep learning works is yet to be developed. Previous work suggests that deep learning performs a coarse graining, similar in spirit to the renormalization group (RG). This idea has been explored in the setting of a local (nearest neighbor interactions) Ising spin lattice. We extend the discussion to the setting of a long ran...
Article
In this paper, the channel model of an indoor amplify-and-forward (AF) hybrid power-line communication (PLC) and visible light communication (VLC) channel is demonstrated using orthogonal frequency division multiplexing (OFDM). Measurements are obtained from different transmitter and receiver setups in an indoor testbed with the aid of a Universal...
Conference Paper
Full-text available
Recently, the use of unmanned aerial vehicles (UAVs) as a relay node has been envisaged as an enabling technology in the upcoming wireless communication era. Thus, in this paper, we consider a full-duplex (FD) cooperative communication system with a source and a destination, where UAV serves as a mobile relay. Here, the transmission power cost is d...
Preprint
The Travelling Salesman Problem (TSP) is an important NP-hard combinatorial optimisation problem that forms the foundation of many modern-day, practical problems such as logistic or network route planning. The Flower Pollination Algorithm (FPA) is a continuous optimisation algorithm that demonstrated promising results in comparison to other well-kn...
Preprint
Full-text available
The development of smart grids has effectively transformed the traditional grid system. This promises numerous advantages for economic values and autonomous control of energy sources. In smart grids development, there are various objectives such as voltage stability, minimized power loss, minimized economic cost and voltage profile improvement. Thu...
Article
Communication and illumination are two basic functions of the indoor visible light communication (VLC). In this paper, a novel spectral-efficient hybrid dimming scheme is proposed for the indoor VLC system, where the frequency-domain subcarrier selection is utilized to maximize the channel capacity and the intensity-domain dimming strategy is used...
Preprint
Full-text available
One of the major challenges for long range, high speed Free-Space Optical (FSO) communication is turbulence induced beam wander. Beam wander causes fluctuations in the received intensity as well as crosstalk in mode division multiplexed systems. Existing models for beam wander make use of probability distributions and long term averages and are not...
Preprint
Full-text available
Although there has been a rapid development of practical applications, theoretical explanations of deep learning are in their infancy. A possible starting point suggests that deep learning performs a sophisticated coarse graining. Coarse graining is the foundation of the renormalization group (RG), which provides a systematic construction of the th...
Article
Full-text available
In this paper, an investigation into the behavior of modern narrowband power‐line communication systems when concatenated with both a fountain code named Luby transform code and a combination of nonlinear preprocessing techniques called signal clipping with blanking is presented. The new systems can be used in applications such as the automatic met...