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TCP congestion control macroscopic behavior for combinations of source and router algorithms

- Dzivhani, Mulalo, Ngwenya, Dumisa, Masonta, Moshe, Ouahada, Khmaies

  • Authors: Dzivhani, Mulalo , Ngwenya, Dumisa , Masonta, Moshe , Ouahada, Khmaies
  • Date: 2018
  • Subjects: TCP Congestion Control , TCP New Reno , TCP Cubic
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/282152 , uj:30402 , Citation: Dzivhani, M. et al. 2018. TCP congestion control macroscopic behavior for combinations of source and router algorithms.
  • Description: Abstract: The network side of Transmission Control Protocol (TCP) congestion control is normally considered a black-box in performance analysis. However, the overall performance of TCP/IP networks is affected by selection of congestion control mechanisms implemented at the source nodes as well as those implemented at the routers. The paper presents an evaluation of macroscopic behaviour of TCP for various combinations of source algorithms and router algorithms using a Dumbbell topology. In particular we are interested in the throughput and fairness index. TCP New Reno and TCP Cubic were selected for source nodes. Packet First-in-First-out (PFIFO) and Controlled Delay (CoDel) mechanisms were selected for routers. The results show that TCP New Reno performs well, in terms of throughput, in a low BDP scenario. However, as expected in high BDP scenario, TCP New Reno deteriorates and TCP Cubic performs better. CoDel in the network side further deteriorates TCP New Reno flows in high Bandwidth-Delay Product (BDP) scenario, while considerably improving TCP Cubic. PFIFO deteriorates both TCP Cubic and TCP New Reno in high BDP. Almost in all cases CoDel seems to improve fairness.
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Error correction enhancement with interleavers for DC free codes

- Musarurwa, Dadiso F., Ouahada, Khmaies, Ferreira, Hendrik C.

  • Authors: Musarurwa, Dadiso F. , Ouahada, Khmaies , Ferreira, Hendrik C.
  • Date: 2017
  • Subjects: DC free , Knuth , Interleaver
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/237840 , uj:24375 , Citation: Musarurwa, D.F., Ouahada, K. & Ferreira, H.C. 2017. Error correction enhancement with interleavers for DC free codes.
  • Description: Abstract: Spectral shaping codes are digital codes especially designed in such a manner that their alphabets give rise to predetermined frequency spectrum envelopes. This implies that the signal energy of these alphabets will be concentrated into a predetermined range of a given frequency spectrum. The design of digital codes in the above mentioned fashion is done in order to match specific channel constraints in the design of transmission, multiplexing or storage systems. In certain applications it is desirable that spectral shaping codes provide some error correction capability or that they possess an increased robustness to errors. These errors may be introduced during transmission, processing or storage of digital information. In this paper, an interleaving method is introduced to increase the robustness of DC free codes toward burst errors whilst maintaining the spectral shaping property of DC free codes. Interleaving when applied to a coded communication system results in a reduction in the mean bit error rate (BER) of coded bit streams.
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Internet of things data integrity

- Matsemela, Gift, Rimer, Suvendi, Ouahada, Khmaies, Ndjiongue, Richard, Mngomezulu, Zinhle

  • Authors: Matsemela, Gift , Rimer, Suvendi , Ouahada, Khmaies , Ndjiongue, Richard , Mngomezulu, Zinhle
  • Date: 2017
  • Subjects: IoT , RSA , AES
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/237484 , uj:24330 , Citation: Matsemela, G. et al. 2017. Internet of things data integrity.
  • Description: Abstract: Internet of Things is an internetwork where people interact with the environment via sensors and machines to perform physical activities remotely. IoT allows objects to be sensed and controlled remotely via internet such as changing the room temperature by controlling an air conditioner, switching on the lights in your apartment, using smart watches to gather information about your body health (blood pressure and heart beat rate) and sends it to your private doctor to monitor it and so on. Performing a research on issues faced with IoT, it was realized that most challenges were of privacy/confidentiality and data integrity. This project further conducts research on finding ways of securing information that is shared between two or more interactive IoT devices. The main objective of the project was to develop a strategy of securing the IoT technology world. The method that was proposed to provide data security and integrity was through cryptographic methods/security algorithms that require decent memory and equitable CPU processing power .There were three security methods that were focused on in this project i.e. RSA, AES and TDES algorithms. Each of the encryption/decryption methods were presented with their detailed design and functionality. The most suitable and better performing security algorithm for IoT technology was chosen according to the measures of time, memory and processing power. With the tests performed on the proposed security algorithms, AES encryption standard seemed to perform better than other security algorithms in terms computational time, memory consumption and the required processing power. The test results also showed that it has a large encryption/decryption key size which also means better protection for data. However through testing of the encryption methods there were shortcomings that were encountered such as inability of the security algorithms to provide authentication and encrypt different data formats such as video, picture and audio. The short comings will be further dealt with on the future work. The success of this research has potential impact on increasing the security of IoT internetwork which intern will increase the number of users in the IoT world.
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Security assessment of the smart grid : a review focusing on the NAN architecture

- Alimi, Oyeniyi Akeem, Ouahada, Khmaies

  • Authors: Alimi, Oyeniyi Akeem , Ouahada, Khmaies
  • Date: 2018
  • Subjects: Smart grid , Cyber-security , Neighbourhood Area Network
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/283770 , uj:30616 , Citation: Alimi, O.A. & Ouahada, K. 2018. Security assessment of the smart grid : a review focusing on the NAN architecture.
  • Description: Abstract: This paper presents a comprehensive review on the security aspect of the smart grid communication network. The paper focus on the Neighborhood Area Network (NAN) cybersecurity and it laid emphasis on how the NAN architecture is such an attractive target to intruders and attackers. The paper aims at summarizing recent research efforts on some of the attacks and the various techniques employed in tackling them as they were discussed in recent literatures and research works. Furthermore, the paper presents a detailed review on the smart grid communication layers, wireless technology standards, networks and the security challenges the grid is currently facing. The work concludes by explaining current and future directions NAN communication security could consider in terms of data privacy measures. The data privacy measures are discussed in terms of prevention and detection techniques.
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Optimal price subsidy for universal internet service provision

- Zhu, Hailing, Ouahada, Khmaies, Nel, Andre

  • Authors: Zhu, Hailing , Ouahada, Khmaies , Nel, Andre
  • Date: 2018
  • Subjects: Universal service , Subsidy , Social welfare
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/282314 , uj:30410 , Citation: Zhu, H., Ouahada, K. & Nel, A. 2018. Optimal price subsidy for universal internet service provision. Sustainability 2018, 10, 1576; doi:10.3390/su10051576
  • Description: Abstract: Abstract: Universal service has been adopted by many countries to bridge the digital divide between Information and communication technologies (ICTs) “haves” and “have-nots”. The key goal of universal service is to provide telecommunications services to “needy persons” at “reasonable” rate. It is, therefore, critical for policymakers to make decisions on what is a “reasonable” price or subsidy for “needy persons” so that the targeted users do utilize ICTs and benefit from them. This paper analyzes universal service subsidies in providing subsidized Internet access from a pricing point of view through a hypothetical scenario where the subsidized users being subsidized through a price subsidyandnon-subsidizeduserssharethesamenetworkoperatedbyaserviceprovider. Wepropose a service differentiation system based on priority queuing to accommodate both groups of users, and model such a system as a Stackelberg game from both a revenue-maximizing service provider perspective and a social welfare maximizing planner’s perspective. We then analyze the optimal prices that maximize the service provider’s revenue and social welfare respectively, investigate how the revenue maximizing price and social welfare maximizing price are effected by users’ willingness to pay and the subsidy ratio, and evaluate the revenue maximizing solution on welfare grounds using the social-maximizing solution as a benchmark. Interestingly, the optimal revenue maximizing solution corresponds to the socially optimal solution in terms of social welfare under the optimum subsidy ratio that maximizes the social welfare. This suggests that the subsidy ratio can be used as a tool to induce the revenue maximizing service provider to set a price that leads to social optimality.
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Mobile sink wireless underground sensor communication monitor

- Ouahada, Khmaies, Rimer, Suvendi, Paul, Babu S., Nomatungulula, Cedrick S., Ngandu, K. G., Longe, Omowunmi M.

Smart home appliances scheduling to manage energy usage

- Alimi, Oyeniyi Akeem, Ouahada, Khmaies

  • Authors: Alimi, Oyeniyi Akeem , Ouahada, Khmaies
  • Date: 2018
  • Subjects: Demand side management , Home energy management system , Smart home appliances
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/281991 , uj:30381 , Citation: Alimi, O.A. & Ouahada, K. 2018. Smart home appliances scheduling to manage energy usage.
  • Description: Abstract: It is imperative to manage household appliances in a cost-effective way to realize efficient energy utilization, reduce spending on electricity bills and increase grid reliability. This study presents a Home energy management system (HEMS) scheduling analysis. The scheduling plan avoids the electricity wastages which arise majorly due resident’s negligence on appliances control. The home appliances employed in the research work are classified in terms of their operating periods. The energy consumption was evaluated using a Fixed Pricing (FP) data. The appliances scheduling plan was developed using Microsoft.net framework with C# Programming language whereas the front end showing the scheduled operating periods for the appliances was developed using Telerik UI framework for Windows forms. Simulation results of the scheduling plan show energy consumption in homes can be planned, monitored and controlled to avoid energy wastage and minimize energy expenditure.
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Narrowband Signal Detection in OFDM Systems Using Spectral Shaping Techniques

- Trollip, Martin, Ouahada, Khmaies, Imoto, Toshiaki

  • Authors: Trollip, Martin , Ouahada, Khmaies , Imoto, Toshiaki
  • Date: 2017
  • Subjects: OFDM , Spectral shaping , Spectral null codes
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/241907 , uj:24939 , Citation: Trollip, M., Ouahada, K. & Imoto, T. 2017. Narrowband Signal Detection in OFDM Systems Using Spectral Shaping Techniques.
  • Description: Abstract: Orthogonal Frequency Division Multiplexing (OFDM) allow data to be transmitted efficiently and reliably by using multiple orthogonal subcarriers. It provides robustness against noise and corruption in the channel. The channel can be either wired or wireless depending on the particular application. Due to the close spacing of subcarriers, OFDM is susceptible to corruption caused by various narrowband signals such as Narrowband Interference (NBI). Spectral shaping shapes the Power Spectral Density (PSD) in order to have certain properties. Spectral shaping might improve the effectiveness of OFDM and make it sustainable in the long run for applications beyond the 4th generation of mobile communications (4G) and Long Term Evolution (LTE). We make use of spectral null codes and load them onto OFDM subcarriers. Introducing narrowband signals in the channel degrades the system’s performance and also eliminates the designed spectral properties. From this observation we infer that some narrowband noise is present in the channel. Previously, carriers hit by NBI or other narrowband noise had to be switched off manually. We found that combining OFDM with spectral shaping allows the presence of Narrowband signals in the channel to be detected and conclusions can be drawn over the channel quality. This did not improve the system in terms of bit error rate performance.
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Distributed optimisation algorithm for demand side management in a grid-connected smart microgrid

- Longe, Omowunmi Mary, Ouahada, Khmaies, Rimer, Suvendi, Ferreira, Hendrik C., Han Vinck, A. J.

  • Authors: Longe, Omowunmi Mary , Ouahada, Khmaies , Rimer, Suvendi , Ferreira, Hendrik C. , Han Vinck, A. J.
  • Date: 2017
  • Subjects: Distributed Energy Generation , Distributed Energy Storage , Demand Side Management
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/237901 , uj:24383 , Citation: Longe, O.M. 2017. Distributed optimisation algorithm for demand side management in a grid-connected smart microgrid. Sustainability, 8(x):1-15.
  • Description: Abstract: The contributions of Distributed Energy Generation (DEG) and Distributed Energy Storage (DES) for Demand Side Management (DSM) purposes in a smart macrogrid or microgrid cannot be over-emphasised. However, standalone DEG and DES can lead to under-utilisation of energy generation by consumers and financial investments; in grid-connection mode, though, DEG and DES can offer arbitrage opportunities for consumers and utility provider(s). A grid-connected smart microgrid comprising heterogeneous (active and passive) smart consumers, electric vehicles and a large-scale centralised energy storage is considered in this paper. Efficient energy management by each smart entity is carried out by the proposed Microgrid Energy Management Distributed Optimisation Algorithm (MEM-DOA) installed distributively within the network according to consumer type. Each smart consumer optimises its energy consumption and trading for comfort (demand satisfaction) and profit. The proposed model was observed to yield better consumer satisfaction, higher financial savings, and reduced Peak-to-Average-Ratio (PAR) demand on the utility grid. Other associated benefits of the model include reduced investment on peaker plants, grid reliability and environmental benefits. The MEM-DOA also offered participating smart consumers energy and tariff incentives so that passive smart consumers do not benefit more than active smart consumers, as was the case with some previous energy management algorithms.
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Moment balancing templates: constructions to add insertion/deletion correction capability to error correcting or constrained codes

- Ferreira, Hendrik C., Abdel-Ghaffar, Khaled A. S., Cheng, Ling, Swart, Theo G., Ouahada, Khmaies

Re-using old cellphones for IoT applications

- Modise, Karabo, Rimer, Suvendi, Ouahada, Khmaies, Ndjiongue, Richard

  • Authors: Modise, Karabo , Rimer, Suvendi , Ouahada, Khmaies , Ndjiongue, Richard
  • Date: 2017
  • Subjects: Smartphone , Android , Arduino
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/237468 , uj:24329 , Citation: Modise, K. et al. 2017. Re-using old cellphones for IoT applications.
  • Description: Abstract: In today’s world smartphones are the most used electronic device as they come with many capabilities that makes everyday life easier. The downside is that smartphones have very short life span and gets damaged easily, hence overtime they get discarded, which adds onto an existing problem of e-waste. Although thrown away, smartphones’ integrated circuits includes components which can be still re-used for other technologies. This project presents a way in which discarding of electronic components without re-use can be combated by making developments in the emerging IoT technology by re-use of smartphone components. To achieve this objective an Android App that requires no use interface and uses only Bluetooth and Wi-Fi components was developed. The App is responsible for giving web capabilities to a maximum of seven Bluetooth enabled sensors, so that the sensors can store their data on a cloud database.
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Effects of spectral null codes on PAPR and BER performance in OFDM systems

- Trollip, Martin, Ouahada, Khmaies

  • Authors: Trollip, Martin , Ouahada, Khmaies
  • Date: 2018
  • Subjects: OFDM , Spectral shaping , Spectral null codes
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/282207 , uj:30404 , Citation: Trollip, M. & Ouahada, K. 2018. Effects of spectral null codes on PAPR and BER performance in OFDM systems.
  • Description: Abstract: Spectral null codes has a wide range of applications, and it has been shown that the Power Spectral Density (PSD) of messages in Orthogonal Frequency Division Multiplexing (OFDM) systems can be shaped to have nulls at designed frequencies. Peak to average power ratio (PAPR) is a common problem with OFDM, resulting in power intensive and more expensive modulators which are not suitable for modern mobile devices with limited battery life. The use of PAPR reduction techniques in OFDM is crucial in order to make it compatible with modern devices. We investigate the effect of spectral null codes on the performance of the OFDM system. In particular we focus on the bit error rate performance (BER) and the PAPR performance. We show that the use of spectral null codes has no negative impact on either the BER or PAPR performance, as expected. We conclude that the spectral null coding technique may be used to shape the PSD in OFDM systems without causing any significant negative impact on performance.
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Binary permutation sequences as subsets of Levenshtein codes, spectral null codes, run-length limited codes and constant weight codes

- Ouahada, Khmaies, Swart, Theo G., Ferreira, Hendrik C., Cheng, Ling

Simulation of wireless sensor node transmission over a multiple access channel

- Ouahada, Khmaies, Rimer, Suvendi, Paul, Babu Sean, Kanyane, Katleho

  • Authors: Ouahada, Khmaies , Rimer, Suvendi , Paul, Babu Sean , Kanyane, Katleho
  • Date: 2014
  • Subjects: Smart grids , Wireless sensor networks , Wireless communication
  • Type: Article
  • Identifier: uj:5047 , ISSN 1867-8211 , http://hdl.handle.net/10210/13586
  • Description: Smart Grids are emerging as a sustainable technology that can greatly improve the quality, cost and efficiency of electrical power distribution. Wireless communication technology, in particular wireless sensor networks, are being considered as a viable solution to Smart Grid communication requirements. Homes have multiple electrical appliances that may communicate concurrently. In addition, electrical appliances induce white noise that can interfere with the wireless signal. In this paper an indoor wireless sensor multiple access communication environ- ment is simulated based on the IEEE 802.15.4 wireless communication standard. An indoor wireless propagation model is implemented and the effects of signal interference on the wireless signal are examined.
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New DC-free multilevel line codes with spectral nulls at rational submultiples of the symbol frequency

- Ouahada, Khmaies, Ferreira, Hendrik C., Swart, Theo G.

Binary permutation sequences as subsets of Levenshtein codes and higher order spectral nulls codes

- Ouahada, Khmaies, Swart, Theo G., Ferreira, Hendrik C.

Viterbi decoding of ternary line codes

- Ouahada, Khmaies

Using graphs for the analysis and construction of permutation distance-preserving mappings

- Swart, Theo G., Ferreira, Hendrik C., Ouahada, Khmaies

Medicines identification for African illiterate patients using near field communication

- Mareli, Mahlaku, Rimer, Suvendi, Paul, Babu Sean, Ouahada, Khmaies

  • Authors: Mareli, Mahlaku , Rimer, Suvendi , Paul, Babu Sean , Ouahada, Khmaies
  • Date: 2014
  • Subjects: Near field communication , Medicines - Identification - Technological innovations , Illiteracy
  • Type: Book chapter
  • Identifier: uj:5040 , ISBN 978-3-319-08368-1 , http://hdl.handle.net/10210/13560
  • Description: This paper presents the application of Near Field Communication (NFC) to the healthcare sector. Although a number of papers have been written to discuss different NFC applications in the healthcare sector, none of them address the potential challenges facing illiterate patients worldwide. According to UNESCO institute for statistics, the Sub-Saharan African region has the highest percentage of illiterate people compared to other regions in the world. NFC can be used in conjunction with other technologies, especially mobile communications which provide high data speeds at cheap rates. The proposed NFC application consists of a NFC sticker placed on the medicine container, the NFC phone with an Android application that reads the sticker ID, connects to a Medicine Information Server and retrieves relevant instructions for medicine in audio form. Some of the advantages for this solution are that the NFC stickers can be recycled.
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Distributed demand side management with battery storage for smart home energy scheduling

- Longe, Omowunmi Mary, Ouahada, Khmaies, Rimer, Suvendi, Harutyunyan, Ashot N., Ferreira, Hendrik C.

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