ABSTRACT. Information and Communication Technologies (ICTs) today permeate every aspect of our lives including the education system. To this effect, a number of Education Management Information Systems (EMIS) have been developed and put to use especially in the developed nations. However, many developing countries, especially in sub-Saharan Africa and South East Asia, are yet to fully exploit the potential of these EMIS(s). Successful management of today’s education systems requires effective policy-making and system monitoring through data and information. Nonetheless, quite often EMIS design and development has been limited to information technology enhancements, and/or data storage and maintenance, with insufficient attention paid to data utilization for policy decisions. This paper proposes a simple revision toolkit whose power is in the utilization of data by applying fundamental artificial Intelligence technique known as K-Nearest Neighbour (KNN) classifiers to enhance utilization of EMIS in delivering the right content to students based on their abilities and also giving their instructors (teachers) a data driven insight into what subjects/sub-topics are posing challenges to students.

ABSTRACT. We present the status of the existing weather observation station network in Tanzania. Relevant information was collected to assess the challenges that should be addressed when planning to automate and densify it. We also recommend new possible sites to be considered in the densification process based on meteorological considerations. Furthermore, possible upstream links, necessary to make data from remote stations accessible, are suggested.

ABSTRACT. Pipeline corrosion is a worldly recognized problem and has been a major concern for owners of pipeline in the past decades. Previous researches have established factors that influence the corrosion of buried pipelines in soil environment. In this work, we focus on analyzing some soil properties such as moisture content, soil pH, plasticity index, soil organic content, soil resistivity, and percentage composition of soil corrosive elements, as it affects underground pipeline. The pipeline of interest is a steel pipeline conveying water and was buried 1m beneath the soil surface. Soil samples were taken around this pipeline at four different sites; mine damp area, vicinity of power lines, an open field of clay soil, and vicinity of a railway line. These soil samples were taken to the laboratory for test and analysis. The results obtained showed that the soil samples from the mine damp area and railway line area are very corrosive to the pipeline while soil sample from the clay soil area is less corrosive. The result of these parameters also showed that soil sample from the power line area is not corrosive to the pipe. Hence, the pipeline which was exposed to soil in the mine damp area and railway line area need to be properly protected to avoid corrosion damage to the pipe.

ABSTRACT. The methods of detecting a recorded speech were analysed and tested according to their applicability in the field of voicemail detection in this paper. Methods chosen for testing were: transmission channel characteristics extraction with PFCC, recorded speech detection with trained pattern classifier, differences in transmission channels and speech recognition. Most of the tests gave results credible enough to confirm methods’ usefulness in the field of voicemail detection. Suggestions of implementation possibilities and parameters of each method and possible trends of further studies were also included.

ABSTRACT. This paper analyzes the asymptotic capacity for upper bound of large antenna Array (Massive MIMO) system with respect to the Rician fading Channel (LOS and NLOS component). We mathematically derived the channel matrix for the Fading signal for the NLOS and LOS by using the Wave Equation. The channel characteristics of the LOS and Scattering Paths are shown. The asymptotic capacity results were verified by using simulations to analyze the K factor characteristic with the Transmit and Receive antennas. The results indicate that when the receive antennas are small the K factor value must be higher (K and for large Receiver antennas the K value must be low (K assuming the transmit antennas are large for both scenarios. We also showed the asymptotic capacity of the Rician channel converges to Rayleigh channel (K = 0) for Large antenna Array. Mathematical expressions for Rician channel capacity have been provided. These results are great contribution to the Beamforming for the Massive MIMO Technology.

ABSTRACT. The use of multiple-input multiple-output (MIMO) systems has been a central part of cellular systems for achieving higher capacity. Distributed antenna system (DAS) is a MIMO system with geographically distributed antennas that provide high coverage and capacity due to the spatial macro diversity. In a multi-user scenario, DAS provides better spatial separation among users. An optimal transmission strategy in a multi-user multi-cell DAS is unknown. We analyze and evaluate downlink capacity of three multiplexing strategies: orthogonal transmission, joint precoding, and space division multiplexing (SDM). Based on the evaluation we propose the most appropriate strategy. The sum-rate has been measured in different scenarios. Simulation results show that DAS has superior performance compared to co-located antennas systems (CAS). It is particularly shown that DAS with simple SDM can provide better capacity than joint transmission in addition to reduced complexity and less feedback overhead. This happens when the number of users increases and remote radio units have single antenna.

ABSTRACT. In this paper, we propose a cooperative Multiple-Input Multiple Output (MIMO) system where the cooperation uses amplify-and-forward (AF) relaying strategy and the MIMO is based on Vertical Bell-Labs Layered Space Time (V-BLAST) architecture. The idea is to simultaneously exploit the advantages offered by cooperative diversity and MIMO and the proposed system is intended for use in Worldwide Interoperability for Microwave Access (WiMAX) technology. Complexity of the cooperative MIMO (Co-MIMO) is also analyzed considering Maximum Ratio Combining (MRC) and Equal Gain Combining (EGC) schemes; Zero Forcing (ZF), Minimum Mean Square error (MMSE) and Maximum Likelihood (ML) detections; and V-BLAST transmission technique at transmitting node. Simulation results show that, at comparable complexity, Co-MIMO achieves significantly better symbol error rate (SER) performance than the conventional cooperative diversity or MIMO system only. As an example, at SER of 10-3, Co-MIMO system using MMSE detection has 10 dB signal-to-noise ratio (SNR) gain over systems that employ cooperative diversity or MIMO only.

ABSTRACT. This paper presents an alternative approach to model the transfer characteristics of power lines for broadband power line communications (PLC). The model is developed by considering the power line to be a two-wire transmission line and the theory of transverse electromagnetic (TEM) wave propagation applied. The characteristic impedance and attenuation constant of the power line are determined through measurements. These parameters are used in model simplification and determination of other model parameters for typical indoor multi-tapped transmission line system. The transfer function of the PLC channel is determined by considering the branching sections as parallel resonant circuits attached to the main line. The model is evaluated through comparison with measured transfer characteristics of known topologies and it is in good agreement with measurements.

ABSTRACT. The power line network presents a readily available medium that can be utilized for the delivery of both low and high data rate communication services. This ready available infrastructure implies that the cost of network set up is very low compared to other technologies, like fiber optics. However, the power line channel is very noisy and presents a hostile environment for communication purposes. But, given the expansive and extensive coverage of the power line network; it presents the most ubiquitous medium, and therefore there is need for a thorough understanding of the channel characteristics, one of the most important being noise. In this paper, we present both parametric and nonparametric models of the noise encountered in an indoor power line network. The models are derived both parametrically and non-parametrically from noise measurements carried out in both frequency and time domains.

ABSTRACT. Power-line communications (PLC) usually suffers from the effects of non-white (correlated) noise, which results from the memory in the channel. In order to combat the effects of the channel memory, interleavers, which introduce a large amount of delay, are often employed together with error control coding. Low-density parity-check (LDPC) codes have been adopted in the recent broadband PLC (BPLC) standards, including the Homeplug AV specification. Analysis of the noise amplitude distribution of each individual frequency component across the PLC noise spectrum has recently shown that noise can be modeled using the generalized Gaussian distribution (GGD). In this paper, an LDPC-coding based receiver that utilizes the GGD noise model is developed, and it is shown that the proposed receiver structure outperforms the conventional receivers designed under the Gaussian noise assumption. Real noise measurements and Homeplug AV specification definitions are employed to demonstrate the high error performance of the proposed receiver structure.

ABSTRACT. In this paper, we describe an ongoing research on an energy efficient key/value store. The focus of the paper is to provide dynamic adaptability to PowerCass [1] which is an energy invariant of Apache Cassandra- a highly scalable distributed data store. The paper addressed the challenge of improving performance through dynamic data relocation while preserving energy efficiency and the fast zero-hop (constant time routing) data lookup attained through consistent hashing in PowerCass. In PowerCass energy efficiency is addressed through 3-way gear leveling in which nodes are classified into three groups: active, dormant, and sleepy and handle high, medium and low load by leveraging usage patterns in data accesses. The energy efficiency results show that the energy consumption of dyn-PowerCass is comparable to the static PowerCass which reduced energy consumption by up to 66% compared to the unmodified Cassandra. The performance results show that the throughput of dyn-PowerCass improved by at least 10% when compared to the static PowerCass and the latency also reduced by the same magnitude.

ABSTRACT. Cloud computing is one of the fastest growing technologies. For developing countries like Ethiopia which has a growing ICT, cloud computing is an attractive choice to adopt. However, the adoption of such a technology should be planned ahead of time taking into consideration the various factors that make adoption successful. The main objective of this research is to propose a cloud readiness assessment framework and an expert system that assesses cloud readiness and recommend which cloud deployment and service model to adopt. The research is grounded by well-studied technological innovation adoption theories: Technology Organization Environment framework (TOE), Diffusion of Innovation (DOI) and Technology Acceptance Model (TAM). Based on these theoretical foundations, a new cloud readiness framework is proposed. A survey is designed based on the framework; using this survey an initial dataset is generated and expanded using synthetic data generator. The expert system relies on predictive modeling for assessing cloud readiness. So, using Weka machine learning platform, J48 decision tree algorithm is experimented using various settings, to train and obtain acceptable model accuracy. Training is performed on the original dataset and synthetically generated dataset. The best obtained model accuracy is 75% with the original dataset.

ABSTRACT. Emerging technologies like Internet and Web services enable a new form of collaboration. An Internet based collaborative environment allows actors with similar profile or interest to publish and share multimedia content. This results in the availability of massive, distributed, heterogeneous and fastmoving streamed multimedia content. In addition, most of the data in the Web describes events associated to people, activities and locations. An event describing a situation might be initiated by a user, followed by a number of users within a specified time period. Extracting events from user contributed multimedia content in collaborative environments is challenging due to three reasons: 1)the content is heterogeneous in source, size and format; 2)users might use different vocabulary to describe the same event; 3)the collaboration environment contains non-events. In this paper, we have proposed an event extraction approach that will be used to build an event-based collective knowledge management framework that assists the retrieval of multimedia contents from various social media sources. This approach is accompanied by experimental results with future works.

ABSTRACT. This research investigates the cost burden of voltage sags and outages of two feeders in typical rural and urban environments in Finland, and compares the effect of different voltage sags on their adjacent feeders. The two tested feeders were each sampled from two 20-kV distribution networks generated by a Network Topology Optimizing Algorithm (NTOA) based on data from a rural area in Western Finland and from the metropolitan region of Helsinki. This study divides the base year into four seasons and considers load data, features and constraints intrinsic to the local scenarios. As inputs to the cost assessment, the reliability technique estimates important reliability indices at each substation. The residual voltages during contingencies, analytically obtained, define the voltage sag rates at several points of the feeders under focus. As main conclusions, voltage sag costs in the simulated feeders are significantly smaller than the outage costs, but voltage sags originating in certain zones of these feeders directly affect voltage levels in other adjacent feeders and upstream equipment, thus propagating the economic burden to other parts of this network.

ABSTRACT. Solar energy is a much discussed renewable resource in South Africa. Possible reasons are on-going energy crisis as well as very high solar radiation intensities in the country. Among numerous technical challenges with increase of solar energy capacity, countries like South Africa must also be very concerned with the cost issues related to renewable energy. In the last decade the cost of photovoltaic (PV) systems has been reduced significantly and the prices are still dropping. Although South Africa can benefit from high solar intensities which can reduce levelized cost of electricity (LCOE) of the solar PV, for the costs involved it is very difficult to compete with coal which is abundant and very cheap in the country. This study shows the influence of penetrating solar PV to the average system LCOE. Optimization programming techniques were employed and a model of South African electricity generation was developed

ABSTRACT. This paper proposes a mathematical predictive model of power energy consumption per household in the district of Antsiranana. Based on the national statistical institute INSTAT, the power consumption depends on the demographic population category. Based on the general daily life equipment per household, the ordinary, medium and rich categories are defined in this investigation. Indeed, the trend from the last two decades yearly survey illustrates how the energy consumption in the district of Antsiranana varies. Based on the time dependent fitting approach, the mathematical model of the energy needs as established. The reliability of the proposed model was assessed with the correlation coefficient R². Based on the data from the last decade, the relevance of the model was investigated. Then, prediction of the energy needs up to 2023 was proposed with 5% relative inaccuracy. Thanks to its simplicity, the method can be useful for the sustainable development. However, further improvement is still needed in order to forecast the energy consumption for tens future decades.

ABSTRACT. Most of the Information and Communication Technology for Development (ICT4D) initiatives introduced to communities in developing countries fails to deliver its promises. In this regards, Participatory Design (PD)assumes to be effective as long as its nature of participatory and methods are contextualized to a given settings. To this end, we discuss the implication of considering local (rural community) culture of participation practices, and proposed a procedure to be followed in the early phases of information system development process. Finally we argue that, such adaption could advance the Participatory Action Research methodology.

ABSTRACT. Eskom is the primary provider of electricity in South Africa. On November 1, 2014, Eskom reported that a coal silo collapsed at its newest power station, Majuba Power Station. The damage at the power station forced Eskom to implement rolling blackouts (called load-shedding) throughout the country. This load-shedding continued into the Christmas season. People flocked to social media to comment about the load-shedding and Eskom in general. The original research project described in this paper was to attempt to map the load-shedding by monitoring Twitter. This was not successful due to the lack of good geolocation data coming from Twitter and was abandoned. The research project was modified to be an attempt at analysing the sentiment of posts about Eskom on Twitter. This was also abandoned because the majority of the posts were negative. There were no positive posts. The final modification to the research project (and the one reported in this paper) is to measure or quantify the relative anger at Eskom in two different tweets. It is important to note that this paper is not about the quality of the electricity supply. It is about measuring people's emotional perception of that supply.

ABSTRACT. The heterogeneous deployment of high-power macro cells and low-power small cells is expected to become the most common approach for operators to meet the increasing demand for capacity in high traffic areas, such as, dense urban hotspots. Furthermore, the recent proposals for operating Long Term Evolution (LTE) networks in the unlicensed spectrum bands (LTE-U) is being considered as an approach for providing additional spectrum for dense small cell deployments. However, the implementation of affordable and flexible small cell backhaul links remains challenging. To that end, self-backhauling the small cells via the existing macro cells as interesting approach, but has limited capacity compared to traditional dedicated backhaul links. In this paper, we investigate possible performance enhancements through the use of LTE-Advanced enhancements, specifically: coordinated multipoint (CoMP) and carrier aggregation (CA), to relax the downlink backhaul capacity bottleneck for self-backhauled LTE-U small cells. We study this proposed approach through system simulations of a selected realistic deployment scenario in a busy area of Addis Ababa. The results of the simulation campaign demonstrate that deployment of self-backhauled LTE-U small cells in dense urban hotspots can provide notable throughput gains, particularly for the case CA enhancements in the small cell backhaul links.

ABSTRACT. The exponential growth in mobile data demand is increasing the need for high capacity provisioning. To satisfy this demand, mobile operators are deploying latest generation of cellular technologies, such as Long Term Evolution. Moreover, the non-uniformity in service demand distribution is creating load imbalance on wireless networks. This imbalance reduces the capacity of the networks and various load balancing strategies are being implemented to circumvent it. This paper investigates a geographic load balancing algorithm, called Bubble Oscillation Algorithm in LTE networks and beyond. The BOA is customized to make it feasible in a real LTE network. A realistic test case network in Addis Ababa, Ethiopia, is used to validate the algorithm and compared it with the default LTE user association criteria, the best Reference Signal Received Power. The numerical results show that, BOA improves users throughput at the cell-edge up to 67.1% as compared to the best RSRP. Considering the number of unassociated users as a second criteria for comparison, service outage for BOA is 7.20% while that of the best RSRP is 40.93% when the service demand is equal to total system capacity, which is a significant improvement.

ABSTRACT. In LTE, establishing a connection requires a relatively complex handshaking procedure. Such an approach is suitable for a system serving only a few high activity users, but it becomes very cumbersome for machine to machine (M2M) traffic, where large amounts of low activity users intermittently transmit a small number of packets. To avoiding excessive signaling overhead, each packet has to facilitate user detection, channel estimation, and data decoding. Even in the case of limited network activity, users may transmit simultaneously, resulting in packet collisions. It has been shown that such traffic can be best served by a Compressive Sensing (CS) detector. However, most of the CS-based multi-user detection (CS-MUD) research deals with Code Division Multiple Access (CDMA) type systems. In this work we propose a CS-MUD algorithm that is designed for single carrier OFDM (SC-OFDM) systems and, as such, can be integrated into LTE uplink subframes. Each packet contains both a user identification code (ID) and data. The CS algorithm uses the ID not only for user detection, but also for channel estimation. We investigate random and structured ID code generation and report system performance in both cases.

ABSTRACT. To identify the influencing parameters for an optimum migration from the legacy network to Long Term Evolution (LTE), this study analyzed LTE technology dimensioning technique on a monopoly mobile telecom operator network. A techno-economic analysis modeling approach was considered. The monopoly and competitive operators’ scenario for LTE deployment was analyzed and a comparative analysis of the feasibility on the two scenarios was conducted over a seven year deployment period. Results show that the monopoly operator can migrate to LTE service within 2 years of the deployment period at a payback period of 1.99 years. In the competitive operators’ deployment scenario, the migrating period become slightly delayed depending on the size of the market share. A market share of less than 10% was found to be difficult to migrate to LTE within the 7 year deployment period due to competition from the significant market players, especially when the number of subscribers is too low. The number of subscribers has a significant effect on the results in both the monopoly and competitive cases.

ABSTRACT. The third generation partnership project (3GPP) long term evolution (LTE) uses high performance strategies such as adaptive link adaptation, multiuser resource scheduling and adaptive MIMO precoding to enhance effective utilization of the availably radio resources. These processes require the transmitter to have an accurate knowledge of the channel state information (CSI). This is typically provided via feedback from the receiver. Due to processing and feedback delays, the CSI used at the transmitter is outdated leading to performance degradation causing a decrease in the overall system capacity. Channel prediction can be used to alleviate this problem. The minimum mean square error (MMSE) has been proven to have high performance in channel estimation and prediction. However this superior performance is accompanied by a high computational complexity. In this paper, we present a low complexity approximate MMSE (aMMSE) algorithm for channel prediction in block fading channels. Simulation results indicate that our proposed algorithm offers superior performance compared to the recursive least squares and normalized least mean square techniques and comparable performance to the full complexity MMSE algorithm.

ABSTRACT. The use of Wireless Sensor Networks (WSNs) has become an essential technology in many application domains including precision agriculture. Node deployment is a key issue in WSNs. In this paper, the nodes will be deployed over a network in a deterministic fashion in which the position of sensor nodes is known before deployment. These nodes are arranged regularly using triangular grid node deployment strategy over the given shape of the monitored region. This approach computes the minimum number of nodes needed to construct a sensor network and determine the position of sensor nodes using spatial coordinates with corresponding node deployment scheme and network topology. It uses real world deployment scenarios (i.e., taking the real shape of the monitored region of farmland) and determines the position of sensor nodes using spatial coordinates and this makes it more practical than others. This approach has to meet various requirements, such as coverage area, network lifetime, cost and ease of deployment, number of nodes, and adaptability. Moreover, we compared hierarchical routing algorithms called PEGASIS and LEACH to evaluate the network lifetime of the proposed scheme since the proposed node deployment scheme has an effect on routing. The results obtained from the implementation and evaluation of the proposed approach achieved the desired requirements and it is applicable to practical environments such as irregularly shaped farmland. We also show that node deployment is affected by the shape of the farmland. Thus, the required number of nodes and their positions can be adjusted adaptively to different shapes of farmlands.

ABSTRACT. Energy conservation is a critical issue in battery power mobile nodes of mobile ad hoc networks (MANETs). Most MANETs routing protocols use some form of flooding to discover routes among mobile nodes. Despite various optimizations, many route discovery messages are still propagated without considering a coalesce effect of node density and residual energy. During route discovery process, each node of MANET should not blindly broadcast because malfunction of node or link might occurs and allows establishing a new path from source to destination which creates extra energy consumption of nodes, sparse network density and a more likelihood occurrence of network partition. In this paper we are developing and evaluating an energy aware routing protocol called a gossip based balanced battery usage routing protocol (GBBU) which integrates minimum residual energy and node degree as cost metric to minimize and distribute energy consumption of MANETs based on Ad hoc on demand distance vector (AODV).The performance of the protocol is measured based on reachability, energy consumed per packet delivered, delivery ratio, average end-to-end delay, network lifetime, number of dead nodes using network simulator-2.35. The simulation results show that GBBU routing protocol minimizes energy consumption per packet and fairly distribute energy usage across mobile nodes.

ABSTRACT. In Wireless Sensor Networks (WSNs), energy efficiency is among the most important factors since the lifetime of an unattended node is limited by its battery lifetime. In infrastructure-less WSNs, in order to use their resources efficiently, nodes can be organized hierarchically. In this case, long range communication is entrusted to a subset of nodes, the Cluster Heads (CHs): each CH acts as a gateway between the local nodes in its cluster and the other CHs in the network. When in this role, a node must stand a heavier traffic and consume more resources: fairness dictates that the role has to be taken in turn by each node in an area that fits the task. However, a selfish node may adopt several strategies to save its energy: it can make itself unavailable for the role of CH, or, when in that role, it can avoid relaying packets. In this work, we study the impact of selfish nodes on the performance of the cluster based algorithm LEACH. By taking into consideration several Quality of Service metrics, we quantify the extent of performance degradation as a function of the percentage of selfish nodes. We show that, when the percentage of selfish nodes is 75%, only 37% of packets reach the base station, network lifetime reduces to 40% of rounds and packet retransmission attempts is close to 63%.

ABSTRACT. Wireless broadcast advantage (WBA) and wireless cooperative advantage (WCA) are exploited in this paper for finding a cooperative route in a wireless mesh network with minimum energy consumption considering practical coding and modulation schemes. In doing so we have assumed a multihop wireless mesh network consisting of nodes capable of adjusting their transmit power. An optimization problem to allocate minimum sum power for a given route subject to a desired end-to-end throughput and outage probability constraints is formulated. WBA and WCA are taken into account separately and together during the resource allocation. Afterwards, optimal and suboptimal route selection is done using a classical Dijkstra’s algorithm. Turbo codes with iterative decoding algorithms are implemented with various QAM modulation schemes.

ABSTRACT. This study investigated the possibility of developing a large vocabulary continuous speech recognizer (LVCSR) for Amharic using the different syllable types V, CV, VC, CVC, VCC and CVCC found in the language as acoustic units. Syllables as longer length acoustic units are able to embed the spectral and temporal dependencies found in speech and thus able to model it well. The recognizer was developed using the Hidden Markov Model as a modeling technique. The result of the experiments shows that syllables are promising units for Amharic LVCSR provided that enough training data is available.

ABSTRACT. This paper reports on a morphological segmentation model for Afaan Oromo based on suffix sequences approach. Understanding and identifying the suffix sequences of a language allow us to detect morpheme boundaries of many words. Morphological segmentation models can be used in many Natural Language Processing applications such as machine translation, speech recognition, information retrieval and partof- speech tagging. A divisive hierarchical clustering and frequency distribution were used to build a tree of candidate stems from which segmented suffix sequences can be modeled. The proposed morphological segmentation model was evaluated with test word-lists. The accuracy obtained by our morphological segmentation model is encouraging.

ABSTRACT. Sign Language uses manual hand and body gestures as well as non-manual facial expressions as a means of communication between deaf and hearing communities. A communication divide exists between the deaf and hearing communities, to the disadvantage of the deaf. This paper explores the design and implementation of a mobile application for South African Sign Language recognition. The application connects, via Bluetooth, to an instrumented glove developed by the University of Cape Town. The objective is to recognize the manual alphabet and manual numeric digits that have static gestures (31 signs in total). Two neural networks (one with a log-sigmoid, and one with a symmetric Elliott activation function) and a Support Vector Machine (SVM) were compared. The SVM was chosen for implementation primarily because of its high accuracy of 99% and its superior robustness. The mobile application is developed for Android and allows the user to connect to a Bluetooth glove, display and dictate the classification output and calibrate the connected glove. On a low-end smartphone, the classification time did not exceed 45ms, the memory usage did not exceed 15 MB, and the battery life during typical usage was approximately 11 hours.

ABSTRACT. Currently there is a tremendous increase in electronic text in various languages, including Ethiopian Semitic languages. Yet, it is inaccessible to visually impaired people and the illiterate. To come up with high quality text to speech synthesizers for local languages, it is imperative that research in natural language processing and synthetic speech generation be improved. Accordingly, we critically reviewed core issues in text to speech synthesis for Ethiopian Semitic languages and revealed that further research to improve the quality of text to speech synthesis for Ethiopian Semitic languages is mandatory. To optimize linguistic resources required for high quality synthetic speech output we propose designing a generic bilingual Text to Speech framework for Ethiopian Semitic languages.

ABSTRACT. This paper presents our investigation of the effect of language resources on the performance of Amharic speech recognition. We have used language model training text of different sizes and seen the effect on word error rate (WER) reduction. Moreover, we have investigated the effect of handling language issues (germination, epenthetic vowel insertion and glottal stop consonant pronunciation) on the performance of speech recognition systems using data-driven phone-level transcriptions. The results of our experiments show that only slight reduction in WER can be obtained by increasing language model training text. However, proper transcription of gemination, the epenthetic vowel and the glottal stop consonant did not bring performance improvement for Amharic speech recognition. This can be attributed to the larger number of phone HMM acoustic models (62 compared to 37 phone set of the grapheme-based phone-level transcriptions) trained with a small (5 hrs) training speech.

ABSTRACT. Self-Excited Induction Generators (SEIG) exhibit a poor voltage and frequency regulation when subjected to load and speed changes. The proposed variable frequency converter (VFC) based Induction generator can provide constant frequency and almost constant voltage feeding ac loads in stand-alone systems without requiring fixed excitation capacitor and a special designed power electronics circuit. The system is designed using off-the-shelf products likes squirrel cage induction machine, an industrial VFC, a dump-resistor, a small LC-filter and a battery for starting up the system. The open loop vector mode operation of VFC provides constant V/f ratio except at low speed to keep the flux constant under varying load conditions. An external dumping load resistor is connected across the DC chopper to regulate varying consumer load. The proposed method has been carried out on a 50 Hz Induction machine with output power of 5.5kW and rated voltage of 400V in delta connection. The experimental result reveals that the proposed induction machine operation as Induction generator (IG) can be effectively used in a rural area to supply ac load with constant voltage and frequency with rated power delivery.

ABSTRACT. The topological properties of power networks emanate from the interconnections of the components within the networks. These structural properties can easily be captured by the network bus impedance or admittance matrix as formulated in the fundamental circuit theory laws (Ohm’s law) for efficient allocation of electric energy among the consumers. In this paper, the solution to load allocation problems within power networks is considered using inherent structural characteristics of power systems. A generalized coefficient matrix called Generation-Load Allocation (GLA) matrix which is a function of the network structural interconnections is formulated. This matrix is employed to determine the percentage allocation of power contribution by each generator to serve the various given loads on the network. The mathematical formulations based on the Ohm’s laws are presented. The simulations were carried out in Matlab 2010a environment. This study uses a practical power network of Nigerian 28-bus system for illustration and results are discussed.

ABSTRACT. The induction machine used as self-excited induction generator in an isolated stand-alone system has inherently a problem of delivering reasonable output power within voltage regulation band without using sophisticated and costly converters. The use of passive elements can be a good solution to provide self-regulation of such generators to be implemented in the rural area where system overall cost and maintenance issues are prerequisite. In this paper, the magnetic saturation zone of the given machine has been explored in optimizing the excitation and series capacitors needed in order to improve the active power delivery capability and voltage profile. An induction machine of 7.5 kW, 380 V (220 V phase voltage) is used as generator and a vector controlled induction machine is used as a prime mover. Two operating points, those corresponding to the maximum permissible voltage band of +6% and +10% above the rated voltage has been taken as focal points to evaluate and compare the active power delivery capability in permissible minimum voltage regulation band. Both the experimental and simulation results are suggesting that a machine which operates in more saturated region of the magnetization curve provides improved result in terms of active power delivery capability and voltage profile without use of a control system.

ABSTRACT. As the number of composite wind turbine generator (WTG) blades in operation rises, rotor blade maintenance is emerging as a major issue. Careful review of the WTG blade lifecycle reveals where damage occurs. Damaged blades can significantly lower WTG performance. A variety of environmental events like lightning strikes, rain and wind erosion are all possible causes of damage. Wind turbulence and changes in wind direction are also contributors. These conditions severely impact the fatigue experienced by the WTG blades and lead to early ‘wear and tear’. In this study, we found that reliability and performance of the WTG blade can be improved by adjusting the center of gravity (CG) and adopting a fiber optic application.

ABSTRACT. In this paper, we describe a system that we have designed and implemented for learning to play electric bass guitar. This system is called EBGeL System or Electric Bass Guitar e-Learning System. EBGeL System includes advanced features for training and practices, and gives feedbacks to users by assessing their performance. It provides models that the electric bass guitar player should follow. Models are represented by musical metadata which have musical components. We describe the steps handled by the EBGeL System for the audio signal processing in order to assess the input audio played by the user: transcription into musical score, extraction of plucking and expression styles, and musical metadata comparison. In particular, the EBGeL System gives marks and reports to users according to their ability with respect to musical rules and playing techniques related to electric bass guitar. That helps the electric bass guitar player to upgrade his level. Experiments indicate that EBGeL System can challenge any methods for learning to play electric bass guitar: users found it easy to use, they appreciated the quickness of the learning process in contrast to the other means of learning to play electric bass guitar.

ABSTRACT. The urge to progressively motivate e-counselling in schools is somewhat dependent on students’ behavioral intention towards the use of the technology. Unified Theory of Acceptance and Use of Technology (UTAUT), a model for predicting behavioral use and acceptance of Information Technology system, was developed through a review and validation of eight exiting theories. This paper presents an empirical approach of using UTAUT model to ascertain students’ behavioral intention to adopt and use e-counselling in Ghana. Questionnaires were used to collect data from two hundred and fifty (N=250) randomly selected students. Cronbach alpha (α) was first employed to validate and ascertain the reliability of the data. Subsequently, Multiple Linear Regression (MLR) was performed in the analysis of the data. Whereas the outcome of the study suggests Performance expectancy (PE) (B = .511 , p= .000) and Social influence (SI) (B = .165 p = .001) as the influencing constructs (factors) towards students’ behavioral intention to adopt and use e-counseling, facilitating condition (FC) (B= .014, p= .723) and Effort expectancy (EE) (B= .086 p= .080) had no significant effect on the behavioral intention of students to adopt and use e-counseling in Ghana.

ABSTRACT. The usage of the Internet of Things technology across different service provisioning environments has increased the challenges associated with service discovery and selection. Users cannot always remember the Internet Protocol (IP) address for every service they need to utilize from the middleware registry. In order to address this challenge, an architecture that enables a representation of user preferences and manipulates relevant services description of available services is developed. This paper, an algorithm derived from the architecture that contributes towards addressing the service selection and discovery problem is proposed. The accuracy of the algorithm is evaluated based on response time, recall and precision metrics. The experiments show that the content-based algorithm works better than collaborative algorithm based on user preference. The content-based algorithm more returns relevant services to the user and takes shorter time as compared to the collaborative filtering.

ABSTRACT. In fading channel when the interfere signal is a random variable, the resulting signal-to-interference-plus-noise ratio (SINR) or signal-to-interference ratio (SIR) is also random and its distribution has to be known for a correct description of the receiver. In this paper, we derive in closed form expression the probability distributions of SIR when more than one Rayleigh distributed interfere signals are present. SINR or SIR involves the sum and ratio of random variables. When the interfere signals are more than one, it becomes very difficult, if not impossible, to obtain a tractable closed form expression of the probability density function (PDF) or cumulative density function (CDF) of SINR or SIR. The SIR is studied in noise limited systems, i.e. where the interfere signals dominate over noise. If the noise is to be accounted for, which is typically AWGN, the SINR may be studied. In our case, adding AWGN has no effect on the overall probability distribution except for a change in its moments. So to keep the mathematical complexity at bay, only the SIR is considered.

ABSTRACT. We consider Down Link (DL) scenario where a Base Station (BS) supports N real-time flows. Each flow requires a hard delay guarantee, i.e., a packet of flow i arriving at time t must depart before t+Di, where Di is the delay requirement of flow i. If a packet is not scheduled before its deadline, then it is dropped. Note that on account of random channel states, packet drop due to deadline violation is inevitable. Fortunately, realtime applications can sustain some loss gracefully. We propose a scheduling algorithm which guarantees that the packet loss due to deadline violation for each flow is below its tolerable limit. Our scheduling algorithm is a randomized scheduling policy where probability of choosing a flow depends on the weight computed for each flow. We provide MATLAB simulation results to study the performance of the proposed schemes and compare them with other scheduling algorithms like Earliest Deadline First (EDF) and Greedy algorithms.

ABSTRACT. In this paper we present a method of detecting and tracking pedestrians from a moving vehicle. We accomplish this by using Histogram of Oriented Gradients (HOG) as a detector and two tracking algorithms, the Kalman filter and the particle filter. The Kalman filter tracks the pedestrians on the road in-front of the vehicle. The particle filter is used to track the pedestrians on the sidewalk or those who are approaching the road from the side, where partial occlusion can occur. By combining these algorithms, we manage to improve the speed and accuracy since the detection algorithm detects the pedestrians, then the tracking algorithm tracks them.

ABSTRACT. The demand for energy is increasing and the need to use renewable sources is rising. One of the key enabling technologies in this domain is smart grid. Smart grid enables the use of renewable energy sources through wind generators or solar panels, for instance. These distributed sources of energy have to be efficiently integrated into the grid through a simple and efficient scheme to synchronize the sources. In this paper, the design and development of a microcontroller based smart grid electricity hub that synchronizes a wind generator to the public supply is presented.

ABSTRACT. A wireless sensor node platform was created along with a base station that can be used to monitor various parameters in the industry. A literature survey was conducted on important parameters found in the industry. The various standards that are set out for these parameters were analysed. The developed wireless sensor node platform along with the base station shows that a wide variety of industrial parameters can be monitored at once from one central place. The simplistic deployment/instalment of the created wireless sensor node platform along with the centralisation of important industrial parameters should appeal to large industries and reduce the risk of accidental unfortunate events.

ABSTRACT. The Ka-band is considered a viable band for future 5G backhaul links. Planar filters in this frequency range have low aspect ratios for substrates thicker than 10 mil, since the required 50 Ω line width becomes comparable to a guided wavelength. This paper proposes the use of grounded through-hole plated vias as transitional combline / evanescent-mode resonators. The principle is demonstrated with a 4th order, 27.5 – 29.5 GHz filter in a conventional 32 mil thickness RF substrate. The simulated filter features below 2 dB insertion loss across the band and occupies 3.8 x 1 mm board space

ABSTRACT. This paper investigates schemes that maximize energy efficiency in cellular networks. We derived the energy efficiency function in terms of system bandwidth, transmission success rate, constellation size, signal-to-noise ratio (SNR) and transmission power. Numerical results indicate that, the transmission success rate function will grow exponentially for an increase in SNR. As a result, the energy efficiency increases linearly when the transmit power is considered constant; however, it increases logarithmically when the transmit power increase proportionally with the system bandwidth. In addition, we showed that the energy efficiency maximization is not necessarily related to rate maximization and use of all available power. With a constant transmit power, the energy efficiency can be increased by 9dB for higher channel gains. Furthermore, it is shown that the energy efficiency can be maximized with a simultaneous increase of both system bandwidth and constellation size without maximizing the transmit power.

ABSTRACT. Energy consumption is a prime concern in the design of most protocols used in wireless sensor networks(WSNs). Mod-elling energy consumption in the network is therefore of high importance for protocol design. Most protocols are built on the basic power consumption model of a wireless communication system. It simply uses the output power of the transmitter’s amplifier, the sensitivity level of the low noise amplifier of the receiving node; without so much focus on how the randomness of the wireless channel environment affects the energy consumption of the network. This paper presents a stochastic modelling approach of the energy consumption in a WSN. The model is stochastic because it considers the effects of the randomness of the wireless environment, the random change of modes of operation and the randomness of the time duration in each mode of operation (Active, Idle or sleep). The model uses a multi-hop Energy-Aware Gradient Based Routing(GBR) protocol.The prime focus lies on modelling in details the energy consumption of the WSN for a single hop transmission level as well as providing a theoretical total energy consumption model taking into account not only the data message but also the different overhead control messages. This energy consumption model can be used to guide design choices at the different layers including the network topology designs, node placement, energy efficient routing and power management schemes. The developed energy consumption model of the EA-GBR is then compared to the one of the generic GBR as well as the Competing GBR.

ABSTRACT. The impact of varying wireless channel on the performance of handover scheme in Low Earth Orbit (LEO) satellite systems operating in different propagation environments, is analytically presented in this work. Generally LEO mobile satellite systems are adversely affected by diverse impairing factors like shadowing and multipath fading which increases the rate of handover failure and blocking of new connections. In essence, this work proposes to adopt the concept of Adaptive Modulation and Coding (AMC) operating at two different transmission rates that suit the channel states of the network. Futhermore, a study of the performance of LEO satellite network in three different propagation environment is presented. In addition, the effect of channel variation on the overall transmission time for these environments is shown by analytical performance measures. The performance metrics considerd for this analysis are the blocking probability of new call attempts (P_b1), handover failure probability due to lack of available resources in the destination cell of the mobile (P_b2), call dropping probability due to an unsuccessful handoff (P_drop,) and unsuccessful call probability (P_ns).

ABSTRACT. Abstract— Energy consumption is a major issue in Wireless Ad-Hoc Networks because the nodes are energy constrained due to minimal power supply. Transmission power is known to be one of the major causes of energy consumption; therefore it must be properly managed. Energy management can be achieved through varying the transmission power with respect to the distance through a technique called Transmission power control. This paper will investigate how transmission power affects consumption of energy in Wireless Ad-hoc Networks. In addition, a Variable Transmission Power Control (VTPC) will be developed in order to minimize the rate of consumption of energy by the nodes in Ad-hoc Networks.

ABSTRACT. This paper studies game-theoretic distributed transmit-power control in a cognitive radio network. It presents a hybrid-adaptive algorithm that interfaces Iterative Water-Filling with two learning algorithms: the Hedging Algorithm and the Historical Matching Algorithm. Iterative Water-Filling helps achieve a fast convergence whereas the learning algorithms help guard against exploitation. The learning algorithms employed are selected based on their performance in deterministic and probabilistic network environments. The hybrid-adaptive algorithm is shown to offer improvements on other methods published. It also performs better than Iterative Water-Filling and the learning algorithms taken in isolation. The main metric is the utility achieved by the players in the game-theoretic setting.

ABSTRACT. With the rapid increase of vehicles on the road, road traffic flow information is indispensible to our daily life. Different Intelligent Transport System applications like advanced Traffic Transport System are dependent on proper road traffic state information. Among the different activities in road traffic flow estimation, road traffic data collection plays the great role. The current state-of-the-practice road traffic data collection tools used to gather information about traffic flow are fixed sensor technologies which are limited in road coverage and affected by maintenance and deployment costs. Using the existing cellular network infrastructure to gather road traffic data offers large coverage capability and it is faster to set up, easier to install and needs less maintenance . Based on the analysis of relevant studies on road traffic state estimation, this paper proposes a universal framework based on experimentally evaluated hybrid Assisted Global Positioning System (A-GPS) and Uplink Time Difference Of Arrival (U-TDOA) real-time road traffic data collection system. The framework integrates several models with appropriate technologies to realize traffic data collection, processing, analysis, state estimation and optimization and presentation of traffic flow information to road users. In Data analysis component a new approach of taking probe sample, i.e. dynamic “Pinpoint-Temporal” sampling frequency method is proposed.

ABSTRACT. This paper presents a novel range-free immune to radio range difference (IRRD) geo-localization algorithm in wireless networks. The algorithm does not require the traditional assumption of anchor (location aware) nodes that have the same communication range as it works with anchor nodes having homogeneous and/or heterogeneous communication ranges. It is rang-free - it utilizes node connectivity to estimate the position of unknown (location unaware) nodes using two or more anchor nodes. The algorithm works in two steps: in the first step, the True Intersection Points (TIPs) forming the vertices of the smallest communication overlap polygon (SCOP) of the anchor nodes are found. In the second step, it estimates the position of the unknown node at the center of the SCOP which is formed from these TIPs. The problem is first geometrically and mathematically modeled, then new localization approach that does not assume anchor nodes have the same radio range is proposed.

ABSTRACT. The amount of information on the web is growing rapidly. Considering a particular group or country, it is very difficult to know how much relevant web contents are published and which are in what language and on what specific subject. Knowing the status of local web content of a country or a culture is of critical importance for making a decision on policy and strategy design for the development of the multi-lingual and multi-cultural web. This research work is therefore to design a model for a local web content observatory system that measure and report periodically the qualitative and quantitative content of different domains. The local Web content observatory system consists of six components – the crawler, content extractor, statistical tracker, language identifier, Web document categorizer and report generator. Though the model developed is generic and can be applied to any country or culture to test and evaluate the system, we have selected all domains hosted under the .et domain. Accordingly about two thousand seed URLs under the .et domain are used and the crawler collected around 263,031 Web documents. According to the accuracy rate measures employed to the language identifier, accuracy rate of 98.67% obtained. To demonstrate the effectiveness of the local Web content categorizer precision, recall and F-measures test were conducted and average precision of 91.7%, recall of 97.2% and F-measures of 94.25% obtained for English document and precision of 91.7%, recall of 87.85% and F-measures of 86.65% obtained for Amharic document. The average accuracy rate of the statistical tracker is 98.72%.

ABSTRACT. This work investigates the feasibility of an integrated terrestrial/satellite network for use in Disaster Management using Nigeria’s NigComSat-1R to provide emergency telecommunication services. The use of NigComSat-1R (42.5oE) on both Ku and Ka bands were analyzed. The worst rain fade calculated was at Calabar and Bayelsa (10.1 dB and 8.8 dB respectively at 99% availability). Calabar gave a rain fade link margin of -0.75 dB at Ka-band, and 1.20 dB at Ku-band (both on NigComSat-1R, but on applying uplink power control from 1 W to 1.5W, the link margin increased to 1.01 dB. NIGCOMSAT-1R on the Ka-band provided the best option with calculated downlink and uplink data rates of 48 Mbps.

ABSTRACT. Abstract— To date, several analyses of diversity systems involve very complex mathematical derivations. These complex methods achieve precise analytical results, but some lack insightful engineering representations which can be used to implement the systems directly. Concerned for equal-gain combiner (EGC), a simple closed-form error analysis of N_r-branch EGC system in the presence of Rayleigh fading is presented. The average output signal-to-noise ratio (SNR) of the EGC combiner is split into equal〖 N〗_r power splitter output SNRs. Since the average output SNR of the splitter equals the sum of the outputs, EGC system reduces to maximal ratio combiner (MRC) whose properties are well known. By devising SNR coefficient for EGC, optimal bit error rate (BER) is derived using the properties of the MRC. Besides an approach of splitter design is illuminated.

ABSTRACT. With an ever increasing number of broadband applications in sub-Saharan Africa, mm-wave point-to-point networking has the potential to fill a niche in communications network architectures. Widespread adoption of this technology would benefit from conventional RF soft substrate integration and packaging, as opposed to system-on-chip or thick film processes. A review on the state-of-the-art in E-band soft substrate systems reveals significant reliance on MMICs. We propose that hybrid integration of active devices with off-chip passives, as well as better integration of active components in SIW, will lead to better performing E-band systems in soft substrates. Specific enabling techniques from the microwave domain are identified.

ABSTRACT. In this paper, 4-year precipitation data obtained from Tropical Rain Measuring Mission-Precipitation Radar (TRMM-PR) satellite were processed and used to determine the distribution of rain height based on 00C isotherm height over Durban in South Africa. The results show that there is a strong variation of bright-band height over the years of observation and will mostly lie between 3639 m and 4197 m above mean sea level. The observed rain height lies between 4517 m and 4803 m. Comparison of the observed results show that the International Telecommunication Union – Recommendation (ITU-R) P.839 recommended values were underestimated. Thus, the specific attenuation values are determined using ITU-R P.618 by incorporating the determined rain height for the location of Durban. It is noticed that the differences between the estimated attenuation based on the measured rain height and the established ITU-R rain height can be as high as 8 dB at Ka band. Thus, recommending using the physical information about rain height derived from the local databases to improve in the rain attenuation prediction accuracy for this region.

ABSTRACT. Recently, a new ICT paradigm emerged, which considers multiple heterogeneous devices that cooperate in multiple signal processing tasks (MDMT). Under this paradigm, cooperation among the nodes can be beneficial when subsets of the nodes share common interests or observations. For cooperation to be successful, it is thus necessary to account for a decentralized labelling scheme that allows to uniquely identify every object of interest. Such labelling not only ensures proper data exchange among the nodes but also allows the formation of interest-specific clusters and hence, might also be beneficial from a communications cost perspective. The research question addressed in this paper is to develop robust distributed labelling strategies in the context of camera networks where no central unit is available for fusing all the information. Simulation results demonstrate that a high labelling accuracy can be achieved in the considered setup (planar scene) with a correct classification performance close to the centralized solution. The proposed methodology is a promising strategy for distributed clustering in camera networks that can be extended to more complex scenarios.

ABSTRACT. Spectrum decision is the ability of a cognitive radio (CR) system to select the best available spectrum band to satisfy dynamic spectrum access network (DSAN) users’ communication needs or quality of service (QoS) requirements without causing harmful interference to licensed or primary users (PUs). In order to have reliable spectrum decision, CR terminals or secondary users (SUs) should identify available spectrum bands and from these candidate spectrum, a CR can select channels which are suitable to meet user QoS requirements. This paper proposes an adaptive spectrum decision framework (ASDF) which is a channel allocation scheme that selects suitable channels from a list of available channels based on SU preferred options. The scheme relies on a geo-location spectrum database (GLSDB) for identification of available spectrum. Key parameters (i.e. available channel bandwidth, time, and power) are extracted from each available spectrum and tagged according to their level in order to build a matrix of available channels. Our ASDF then maps channels with SUs based on channel properties and SU preferred options. Simulation results show that our ASDF is reliable and consistent when it comes to channel selection. Furthermore, our scheme provides efficient bandwidth utilization when compared to the first come first serve channel allocation scheme.

ABSTRACT. This paper presents joint adaptive modulation and adaptive multiple-input multiple-output (MIMO) system (JAMAMS) in Long Term Evolution (LTE) network that adapts both modulation type and MIMO scheme based on channel conditions. Specifically, four adaptive modulation-based MIMO techniques, namely, 1 X 2 MIMO with maximum ratio combining (MRC); 2 X 1 and 2 X 2 Alamouti techniques; and 2 X 2 Vertical Bell Labs Layered Space-Time Architecture (V-BLAST) are investigated. Bit error rate (BER) and spectral efficiency (SE) are used as performance metrics and Zero Forcing (ZF) detection is used in all the MIMO techniques. For each of the four techniques, first the signal-to-noise ratio (SNR) thresholds for switching from one modulation order to the next (i.e., adaptive modulation) are determined. Then, based on comparison of the thresholds of the four schemes, a proposal is made when the system has to switch from one MIMO scheme to the other; and the resulting system is called JAMAMS. The proposed system has shown better SE performance in comparison to fixed scheme, while satisfying target BER constraint, 〖BER〗_th≤〖10〗^(-2). Moreover, it is shown that JAMAMS has comparable computational complexity in comparison to fixed MIMO systems.

ABSTRACT. In this paper we focus on the use of power optimization for maximizing the network lifetime of wireless sensor networks. The goal of this paper is to improve on the algorithm suggested by Cardei et al. for solving the adjustable range set cover problem. We suggest applying the technique of Lagrangian relaxation to the integer linear programming problem formulated by Cardei et al. and using the dual variables obtained from solving the relaxed linear program as the initial values of the Lagrangian multipliers. The results of using the proposed algorithm on small examples are then compared to the results of using the methods suggested by Cardei et al. on the same examples.

ABSTRACT. Time-frequency analysis is an evolution of mathematical ideas and concepts used in the analysis of time-varying spectra of signals in order to cater for various problems in different fields. One of such fields of interest is radar related problems. This paper reviews the recent advancements made in this area with the aid of time-frequency (t-f) tools within the last year till date, it presents a good starting point for researchers interested in radar applications of t-f analysis. It investigates the nature of tools used, the problem(s) solved, advantages and limitations of method used where applicable. Illustrations of some basic concepts are also presented when necessary. The short time Fourier transform (STFT) and Wigner-Ville distribution (WVD) still remain the two main key time-frequency distributions that have undergone various modifications to mitigate radar related problems. It is also seen that considerable amount of most recent works deals with micro-Doppler identification and radar signals analysis.

ABSTRACT. Determining the level of pulse repetition interval (PRI) agility is important in the field of Electronic Intelligence (ELINT) in order to provide warning receiver and jammers with the appropriate information in order to take action. This paper uses smoothed instantaneous power in order to estimate the PRIs of an incoming radar emitter signal. The test signals considered for this work is made up of simple pulsed and staggered PRI radar signal of various intervals and position. The algorithm designed uses the Hilbert transform to obtain the analytic version of the incoming signal before the Hamming smoothed instantaneous power is applied to the signal. Thereafter, first, second and third PRI are obtained and used to form rules for the rule-based Classifier. The rule-based classifier classifies the signals in order to determine the level of PRI agility. Performance analysis is carried out in the presence of additive white Gaussian noise (AWGN) for 100 iterations. Results obtained showed that a 100 percent probability of correct classification is obtained at signal-to-noise ratio (SNR) equal or greater than 3dB irrespective of the incoming signal.

ABSTRACT. In heterogeneous wireless networks (HWNs), it is important to select a currently optimal network for applications demanded by communicating Mobile Nodes (MNs) through Vertical Handover (VHO). VHO problem in HWNs is modeled as a multi-criteria decision making (MCDM) problem. VHO process is very vital in HWNs networks and thus demand the application of very efficient MCDM algorithms. The use of efficient MCDM algorithms for heterogeneous network selection can provide MNs with satisfactory Quality of Service (QoS). We propose a novel MCDM algorithm called MULTIplicative form with Multi–Objective Optimization Ratio Analysis (MULTIMOORA). The performance of the MULTIMOORA is validated by comparing it with SAW, GRA, VIKOR and TOPSIS algorithms for voice, file download and video streaming traffic classes. Simulation results show that MULTIMOORA outperforms SAW, GRA and VIKOR. Moreover, results show it has similar performance with TOPSIS, in term of accuracy for all the network traffics considered.

ABSTRACT. The selection of the most appropriate access network during handover or data offloading in heterogeneous wireless networks plays a vital role in providing the required Quality of Service (QoS) to mobile subscribers. The 3rd Partnership Project (3GPP) has therefore introduced the Access Network Discovery and Selection Function(ANDSF) in the core network to provide the user equipment(UE) with the required information for the discovery and selection of non-3GPP networks such as wireless Local Area Network (WLAN). Current ANDSF provides statically configured information which cannot guarantee the user QoS requirements. The proposed solution in this paper presents a scheme that provides the ANDSF with real time network performance indicators, which are used as input to a multi attribute decision making (MADM) algorithm implemented in the ANDSF for ranking of available access networks and providing inter system mobility policy to the UE. The results show an efficient access network selection policy that can provided the UE with the appropriate target access network for data offloading.

ABSTRACT. Fractional frequency reuse scheme is an interference mitigation scheme suitable for multi-tier networks. However, critical examination of existing fractional frequency reuse schemes based on the orthogonal frequency division multiple access technique for a multi-tier network consisting of Macro-cells and Femto-cells reveals a cross-tier, cross-boundary interference for the Femto-cell users located at the boundary region of the cell centre and edge region. In this paper, we addressed this interference issue by introducing a modified resource allocation scheme that adds a buffer zone between the centre and edge region. In addition, the hybrid spectrum usage concept was incorporated into the proposed design to determine the extent of the buffer zone. System level simulation results showed our technique significantly improved signal to interference plus noise ratio (SINR) and throughput performance for the Femto-users located at the boundary region when compared to the traditionally existing scheme.

ABSTRACT. This paper presents a Call Admission Control scheme for an Interactive Multimedia Satellite network that employs a link adaptation technique to overcome the effect of the time-varying characteristics of the satellite channel. By associating users’ channel states to particular transmission parameters, the amount of resources required to satisfy user connection requirements will vary as the channel state varies. In the proposed system, adaptive modulation and coding (AMC) is employed for transmission over the time-varying wireless channel of the return link of an interactive satellite network. The proposed CAC policy therefore considers the effect of AMC in its operation. The results show that the performance of the system is better than that of systems that do not consider effects of the time-varying wireless channel of the return link.

ABSTRACT. Low Earth Orbit (LEO) satellites have appealing characteristics that make them most adequate for the provision of ubiquitous wireless service. However, frequently occurring handover across satellite spotbeams (due to the high mobility of LEO satellites) is a serious shortfall that needs to be addressed. Handover management issues are solved by an efficient handover algorithm and proper resource allocation. An Adaptive Handover Scheme (AHS) is proposed to address handover issues in LEO satellite networks. The proposed scheme, utilizes a resource allocation strategy that considers the varying characteristics of the wireless channel. Furthermore, AHS provides users with improved Quality of Service (QoS) by keeping Connection Blocking Probability (CBP) and Connection Dropping Probability (CDP) at an acceptable level. The performance results of the developed handover algorithm show an improvement in the CDP and CBP of new and handover connections.

ABSTRACT. This paper presents a range-free selective anchor node center of the smallest communication overlap polygon localization algorithm in wireless networks. The algorithm is range-free which does not require ranging devices. To estimate the location of unknown (location unaware) nodes it uses node connectivity based on selected anchor (location aware) nodes. The algorithm first selects appropriate anchor nodes. Then, the True Intersection Points (TIPs) constituting the vertices of the smallest communication overlap polygon (SCOP) of these selected anchor nodes' communication ranges are found. Finally, the location of the unknown node is estimated at the center of the SCOP which is formed from these TIPs. The algorithm performance is evaluated using MatLab simulation and compares favorably to state-of-the-art algorithms: Centroid, improved version of CPE, Mid-perpendicular and CSCOP localization algorithms. The results show the proposed algorithm outperforms other state-of-the-art algorithms in location accuracy and it has reasonable computational complexity.

ABSTRACT. Abstract—The switching of high-voltage capacitor banks for reactive power and voltage control usually generates significant transients. These high amplitude disturbances have a tendency to damage or reduce the lifespan of capacitor units, thus leading to complete failure of capacitor banks. Pre-insertion resistors or inductors as well as synchronous switching (Point on Wave) methods can be used to mitigate transient phenomenon. In this work, Electromagnetic Transient Program simulations of transient voltage for single and back to back capacitor banks indicate that pre-insertion resistors methodology can significantly reduce transients, and could therefore be combined with synchronous switching to effect transient mitigation.

ABSTRACT. Checking the vulnerability and vulnerability history of green economy friendly critical infrastructures such as hydroelectric, wind, or solar power control systems is essential part of keeping the security intact. Vulnerability reports are one of the most important security tools for security experts to check vulnerabilities. In this paper over 40,000 vulnerability reports from SecurityFocus’s vulnerability database BugTraq are studied and the reports are analyzed accordingly to understand the type of vulnerability contributors, the motivation of the contributors, the trend of most common vulnerability types, and the amount of vulnerability reports over the years. It is shown that most of the vulnerabilities are reported by open source vendors and security organizations. Vulnerability reports are also shown to be decreasing since 2006 and more than 70% of the reported vulnerabilities are contributed by less than 10% of the members. It is also observed that remote code, cross-site, and denial of service vulnerabilities have become dominant vulnerability types reported recently. This research can be used by security system designers and planners to better understand the historical perspective of vulnerabilities. It enables better understanding of vulnerabilities ensuring improved robustness against vulnerabilities. Future work is suggested to extend the analysis to other equally popular vulnerability reporting databases and also add more security measurement parameters.

ABSTRACT. Faulty insulator causes the change of voltage and electric current, which generates great damage in power grid. It is therefore important to monitor and inspect the insulator to assess damage that could be caused by aging or any accident on power line system. Computer vision has been identified and is being investigated as a tool to solve this problem more safely, accurately and speedily. Identifying the region where the insulator is located is crucial in the process of assessing its status. The insulator can then be segmented and fed to defect detector. In this paper we proposed an insulator segmentation framework from plain and complex background using active contour model and extracting insulator region of interest. Experiment shows that active contour model successfully segments insulators from a plain and complex background by evaluating the result with a manually created ground-truth. This method is more efficient, flexible, and outperforms the classical methods such as thresholding and gradients based approach.

ABSTRACT. In this paper a two degree of freedom parallel robot is modeled using the principle of virtual work. In order to achieve smooth trajectory tracking a regularized third order sliding mode controller is developed. Simulation results show that steady state tracking is met in approximately 2 seconds for a circular trajectory of 300 mm radius. The maximum tracking error is shown to be 4mm. Chattering is eliminated and the closed loop system is also shown to be robust against external disturbances and mass uncertainties.

ABSTRACT. Spatial demosaicking methods are attractive due to their robust reconstruction capabilities and low computational load. This paper presents a new gradient-based spatial demosaicking algorithm with contributions from combinatorial geometry. It introduces the use of square tiling primitives called pentominoes to dictate the difference-term pairs combinations for gradient generation. The proposed algorithm is compared with current established methods. Reconstruction performance is objectively measured using three commonly documented metrics(MSE, SSIM and CPSNR). Three different image sets are used (Kodak, McMaster-IMAX and Condat) to evaluate demosaicking robustness. An significant improvement in performance over existing methods has been obtained through MATLAB simulation.

ABSTRACT. Intelligent energy networks (or Smart Grids) provide efficient solutions for a grid integrated with near-real-time communication technologies between various grid assets in power generation, transmission and distribution systems. The design of a communication network associated with intelligent power system involves detailed analysis of its communication requirements, a proposal of the appropriate protocol architecture, the choice of appropriate communication technologies for each case study, and a means to support heterogeneous communication technology management system. This paper discuses a mechanism for on-line configuration and monitoring of heterogeneous communication technologies implemented at smart energy system testbed of Aalborg university. It proposes a model with three main components, a network emulator used to emulate the communication scenarios using KauNet, graphical user interface for visualizing, configuring and monitoring of the emulated scenarios and a network socket linking the graphic server and network emulation server on-line. Specifically, our focus area is to build a model that gives us ability to look at some of the challenges on implementing inter-operable and resilient Smart Grid networks and how the current state of the art communication technologies are employed for smart control of energy distribution grids.

ABSTRACT. In the light of economic development and population growth, annual electricity demand in Ghana has correspondingly increased. This has led to excessive pressure on the power system, especially as power generation has been inadequate to meet the increasing demand. As at the end of the year 2013, 25% of the approximately 25 million Ghanaians still lacked access to the national electricity grid. Thus, in order to augment the generation capacity deficit and increase the electricity access rate, strategic planning and extensive expansion of the Ghanaian power system are urgently required. Renewable energies offer a wide range of benefits, which could be exploited to concurrently supplement the generation deficit and expand electricity accessibility. However, although these matters have been issues of great concern in the country, very little research has been done, especially with regard to the roles of renewable energies in Ghana. This paper therefore considers the prospects of renewable energies in Ghana and how they could be utilized in the power sector. In view of this, current challenges in the Ghanaian power sector, particularly with power generation are also presented.

ABSTRACT. Monthly expenditure on electricity by most households in South Africa take beyond acceptable percentage of their income. In order to keep the household energy expenditure below the energy poverty threshold, a daily electricity optimization problem is formulated using mixed integer linear programming (MILP) method. The energy optimization scheduling was carried out by a device called the Daily Maximum Energy Scheduling (DMES) device proposed to be incorporated into smart meters of households. The DMES algorithm was tested with household data set and was shown to be capable of ensuring that households spend less than 10% of their income on electricity bill monthly. This technique therefore, would be beneficial to consumers (for better financial savings and planning), utility (for effective energy and financial savings, and energy network planning) and cleaner environments as proposed for smart grid. Also, number of households in the nation living below the energy expenditure-based poverty threshold would increase.

ABSTRACT. Sustaining successful e-government initiatives is of paramount importance for governments of developing countries. However, extant literature indicate that failure of e-government initiatives in those countries is very high and this demonstrates that the issue is challenging and also poorly understood. Sustainability aspect of e-government initiatives is a neglected topic and calls to extend e-government research beyond success. This research tries to explore the potential relationship between the two concepts (e-government success and sustainability) in an integrated manner. The paper presents a case of a G2G e-government project in Ethiopia and structurational model of technology was used as a theoretical lens. The study proposes a conceptual framework for understanding success and sustainability of e-government initiatives by uncovering the relationship between the enablers of e-government success and sustainability considering the role of IT-enabled administrative processes as a potential trajectory between the two concepts. The outcome of the research is also of value for practitioners as a quality tool to assess success and sustainability aspect of e-government initiatives.

ABSTRACT. Ethiopia, one of the poorest countries in the world, has been providing a haphazard and poorly structured Public Information Services (PISs) for decades. Effective PISs are channels of delivery of full-fledged digital information through electronic platforms from and to citizens on time. Accordingly, the Government has already recognized the role of Public–Private Partnerships (PPPs) to enhance sensitive PISs and realize its GTPs (Growth and Transformation Plans) despite the country’s lack of clear regulatory framework of PPPs. A PPP is an agreement which could be signed by both the state and private sectors to deliver basic public demands on-time to citizens and PIS is a mode of implementing a digital and networked electronic service (e-Service) platform to citizens based on a common public interest. However, analyzing rigorously how to deliver basic PISs through PPPs and transform various state based sectors into an effective system has been an open question for the current Ethiopian practitioners. Through PPP, the private sector could play a role by contributing its flexible resources, expertise, and importing cutting-edge technologies thereby providing the rural and urban populaces with desired PISs. However, the readiness of the public sector to form partnerships with the private sector is minimal because establishing such a strong partnership is a complex phenomenon with several soft-factors including social and political. Being aware of this, the Ethiopian government has just started inspiring potential private sector actors in order to invest and improve the quality and delivery of basic PISs throughout the country. Although small in number, studies of other countries point out that many such initiatives tend to fail due to numerous causes. Furthermore, in developing countries, there are reported reality gaps, of various nature, regarding the impact of PPP initiatives as a mechanism to assuring the proper delivery of basic PISs. This study, therefore, is designed to analyze the soft factors of PPP initiatives that might help to adapt useful PPP models, relevant to the Ethiopian context, which ultimately help create successful, stable and quality PISs. A guiding theoretical foundation of this study is Soft-Systems Methodology (SSM). The study also intends to provide Ethiopian policy makers with a mechanism that will assist them to improve the delivery of basic PISs in the country.

ABSTRACT. African border posts have long been characterized by high levels of inefficiency, resulting in long cross-border delays that hamper the African economy. This partly results from the conflicting objectives of the multiplicity of stakeholders: while cargo owners and transporters focus on short turn-around times, the priority of customs authorities is to prevent the movement of illegal contraband and to optimize the collection of customs duties. In the paper we demonstrate that it is possible to further the objectives of all stakeholders by using automated identification technologies to monitor the status of freight consignments and by sharing of such data amongst key stakeholders. We describe the development of a simulator to model cross-border processes and experiment with different simulated scenarios to determine the impact of potential new measures on cross-border delay times. The simulator is calibrated based on the results of physical cross-border time delay studies. It is then demonstrated that the use of technology to implement a system of Green and Red Lanes, combined with the dynamic adjustment of customs processing capacity, can have a very significant positive impact on cross-border efficiencies.