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Access to quality healthcare is a major problem in Sub-Saharan Africa with a doctor-to-patient ratio as high as 1:50,000, which is far above the recommended ratio by the World Health Organization (WHO) which is 1:600. This has been aggravated by the lack of access to critical infrastructures such as the health care facilities, roads, electricity, and many other factors. Even if these infrastructures are provided, the number of medical practitioners to cater for the growing population of these countries is not sufficient. In this article, how information and communication technology (ICT) can be used to drive a sustainable health care delivery system through the introduction and promotion of Virtual Clinics and various health information systems such as mobile health and electronic health record systems into the healthcare industry in Sub-Saharan Africa is presented. Furthermore, the article suggests ways of attaining successful implementation of telemedicine applications /services and remote health care facilities in Africa.

This work investigates and show the performance of destination assisted node in ensuring secure communication in a dual-hop broadcast system. The information transmission occurs between the transmitters which are assumed to be equipped with single antenna through a number of intermediate untrusted relays to the receiver in the presence of multiple passive eavesdroppers. This work assumes that there is no direct link between the transmitter and the receiver and hence, the relay node, receives either the information or noise signal at every transmission processes. Since the transmission occurs in a two-phase, the legitimate receiver is contributing a degrading noise to both the eavesdropper and relay node channels during the first phase while it receives information from the transmitter through the relay during the second phase. Simulation results are used to illustrate the performance of the proposed scheme.

Smart city adoption and deployment has taken the centre stage worldwide with its realisation clearly hinged on energy efficiency, but its planning is threatened by the vulnerability of smart grids (SGs). Adversaries launch attacks with various motives, but the rampaging electricity theft menace is causing major concerns to SGs deployments and consequently, energy efficiency. Smart electricity meters deployments via the advanced metering infrastructure present promising solutions and even greater potential as it provides adequate data for analytical inferences for achieving proactive measures against various cyberattacks. This study suggests the sources of threats as the first step of such proactive measures of curbing electricity thefts. It provides a framework for monitoring, identifying and curbing the threats based on factors indicative of electricity thefts in a smart utility network. The proposed framework basically focuses on these symptoms of the identified threats indicative of possible electricity theft occurrence to decide on preventing thefts. This study gives a useful background to smart city planners in realising a more reliable, robust and secured energy management scheme required for a sustainable city.

Today, the world is technology-driven and so of these technologies are driven using wireless systems. Signal coverage and quality of service are pertinent for network providers and path loss prediction is very important in the design and planning of these systems. However, the inefficiency of conventional propagation models, such as empirical, deterministic and theoretical models has been established in previous research works. The machine learning methods have recently been applied for prediction of path losses. The Adaptive Neuro-Fuzzy Inference System (ANFIS) technique is one of the machine learning techniques that has been successfully employed to predict path losses in different environments. However, the performance of the ANFIS-based models in terms of the computational complexity and accuracy depends on the selection of the appropriate system parameters. This paper, therefore, investigates the effect of number and shape of membership function (MF), and training data size on the performance of ANFIS model for predicting path losses in the VHF and UHF bands in built-up environments. Path loss propagation measurements were conducted in four cities of Nigeria over the cellular and broadcasting frequencies. A total of 17 broadcast transmission and cellular base stations were utilized for this study. From the results obtained, it can be concluded for the broadcasting bands that the generalized bell MF shows better performance with an average RMSE of 3.00 dB across all the routes, followed by gaussian, Pi, trapezoid and triangular MFs in that other with average RMSE values of 3.09 dB, 3.11 dB, 3.16 dB and 3.23 dB respectively. For the cellular systems, Triangular MF outperformed other MFs with the lowest average RMSE. The generalized bell MF was found to be suited for WCDMA band while triangular MF is most suited for GSM band. Furthermore, it can also be concluded that the higher the number of membership functions, the lower the RMSE, whereas, a decrease in the data size leads to a reduction in the RMSE values. The findings of this study would help researchers and network planners to make a more informed decision on choosing appropriate system parameters when modelling ANFIS models for path loss prediction.

For decades now, a lot of radio wave path loss propagation models have been developed for predictions across different environmental terrains. Amongst these models, empirical models are practically the most popular due to their ease of application. However, their prediction accuracies are not as high as required. Therefore, extensive path loss measurement data are needed to develop novel measurement-oriented path loss models with suitable correction factors for varied frequency, capturing both local terrain and clutter information, this have been found to be relatively expensive. In this paper, a large-scale radio propagation path loss measurement campaign was conducted across the VHF and UHF frequencies. A multi-transmitter propagation set-up was employed to measure the strengths of radio signals from seven broadcasting transmitters (operating at 89.30, 103.5, 203.25, 479.25, 615.25, 559.25 and 695.25 MHz respectively) at various locations covering a distance of 145.5 km within Nigerian urban environments. The measurement procedure deployed ensured that the data obtained strictly reflect the shadowing effects on radio signal propagation by filtering out the small-scale fading components. The paper also, examines the feasibilities of applying Kriging method to predict distanced-based path losses in the VHF and UHF bands. This method was introduced to minimize the cost of measurements, analysis and predictions of path losses in built-up propagation environments., Path loss measurement, Kriging Interpolation Method, prediction model, radio propagation

Path loss propagation is a vital concern when designing and planning networks in mobile communication systems. Propagation models such as the empirical, deterministic and theoretical models, which possess complex, inconsistent, time-consuming and non-adaptable features, have proven to be inefficient in designing of wireless systems, thereby resulting in the need for a more reliable model. Artificial Intelligence methods seem to overcome the drawbacks of the propagation models for predicting path loss. In this paper, the ANFIS approach to path loss prediction in the GSM and WCDMA bands is presented for selected urban areas in Nigeria. Furthermore, the effects of the number of Membership Functions (MFs) are investigated. The prediction results indicated that the ANFIS model outperformed the Hata, Cost-231, Egli and ECC-33 models in both Kano and Abuja urban areas. In addition, an increase in the number of MFs conceded an improved RMSE result for the generalized bell-shaped MF. The general performance and outcome of this research work show the efficiency and usefulness of the ANFIS model in improving prediction accuracy over propagation models

This paper has presented a comprehensive review in the area of microgrid from the design to implementation. The aim is to evaluate the current status, problems and research efforts toward realising functional microgrids in the power system. The expectations about microgrid are many; therefore the study is divided into three main sections. Recent advancements in the wind energy, solar energy and their future prediction are summarised. States of arts in optimum design of renewable energy microgrid are also investigated. In addition, critical literature review in the reliability analysis of microgrids consisting of renewable energy sources is also reported. Control of microgrids consisting renewable energy sources have been presented. Some examples of existing microgrids across the globe are critically reviewed. The work therefore recommends that energy planners and all stakeholders should consider environmental and regional difference in microgrids planning. Finally, future research areas and directions in these areas are highlighted.

In recent years, the evolvement of mobile devices which perform sophisticated functions have been on the rise. Mobile applications which solved engineering challenges are now available due to the high computational capabilities, large random access memory and storage location of the mobile devices. An Android application called signal detect, which measures network signal strength value from 2G-4G received on an android mobile device has been developed using android app development environment called Android studio. Validation becomes necessary because different readings were obtained on smartphones with different specifications. Two validation techniques were used to validate the data obtained. To know the efficiency of the application; a field strength meter was used to compare the readings received on the mobile device with the meter. It was observed that there is a time lag on the received values of the mobile device to the field strength meter. Therefore, a moving average technique was used to correlate the two data which increased the correlation coefficient to about 0.85.

Artificial Neural Networks (ANNs) have been recently exploited to develop suitable models for path loss predictions . However, the ANN algorithm that provides the best results has not been well established neither has the models been characterized to limit their performances and applications in the various frequency bands. In this paper, we characterize the propagation path loss in the Very High Frequency Band (VHF) using different ANN learning algorithms and activation functions based on the measurement data collected at 203.25 MHz in an urban environment (Ilorin, Nigeria). The prediction results of Hata, COST 231, ECC-33, and Egli models at varying distances were fed into a feed-forward neural network and mapped to each corresponding measured path loss value. Statistical analysis shows that the ANN model that was trained with hyperbolic tangent activation function (HTAF), Levenberg-Marquardt (LM) algorithm, and 80 neurons in the hidden layer produced the most satisfactory results with Mean Error (ME), Root Mean Square Error (RMSE), Standard Deviation (SD), and coefficient of determination (R2) values of 3.75 dB, 5.10 dB, 3.46 dB, and 0.95. However, the HTAF with Scale Conjugate Gradient (SCG) is more stable even though its prediction errors were slightly higher than that of LM.

The Almajiri children in Nigeria are deserving of special interventions to reduce the life-long divide in educational achievement, social status, and economic empowerment. One way of speedily achieving this is through the use of Information and Communication Technologies (ICTs). This study examined the prospects and challenges of using ICT in the teaching and learning processes of Almajiri children’s education in Nigeria. A descriptive research methodology was adopted and data were collected from the Almajiri children, their teachers, and parents from communities with a high concentration of Almajiri schools. The results showed that while the official language of instruction in schools in Nigeria is English, the language often spoken by children and teachers was Hausa. Also, while teachers and parents were quite familiar with ICTs such as mobile phones, computers, and television, the Almajiri children were more familiar with television and mobile phones, and very few had used a computer. Some strategies proposed for successful adoption of ICT in Almajiri education include the use of indigenous languages in courseware development and the use of one-to-many ICT facilities, such as multimedia teaching aids, projectors, and smart televisions.

Access to quality education is still a major bottleneck in developing countries. Efforts at opening the access to a large majority of citizens in developing nations have explored different strategies including the use of multimedia technology. This paper provides a systematic review of different multimedia tools in the teaching and learning processes with a view to examining how multimedia technologies have proven to be a veritable strategy for bridging the gap in the provision of unrestricted access to quality education and improved learners' performance. The review process includes conducting an extensive search of relevant scientific literature, selection of relevant studies using a pre-determined inclusion criteria, literature analysis, and synthesis of the findings of the various studies that have investigated how multimedia have been used for learning and teaching processes. The review examines various case study reports of multimedia tools, their success and limiting factors, application areas, evaluation methodologies, technology components, and age groups targeted by the tools. Future research directions are also provided. Apart from text and images, existing tools were found to have multimedia components such as audio, video, animation and 3-D. The study concluded that the majority of the multimedia solutions deployed for teaching and learning target the solution to the pedagogical content of the subject of interest and the user audience of the solution while the success of the different multimedia tools that have been used on the various target groups and subjects can be attributed to the technologies and components embedded in their development., Education, Media in education, Teaching/learning strategies, Pedagogical issues, Systematic review

Path loss prediction is an important process in radio network planning and optimization because it helps to understand the behaviour of radio waves in a specified propagation environment. Although several models are currently available for path loss predictions, the adoption of these models requires a trade-off between simplicity and accuracy. In this paper, a new path loss prediction model is developed based on an Adaptive Neuro-Fuzzy Inference System (ANFIS) for multi-transmitter radio propagation scenarios and applicable to the Very High Frequency (VHF) bands. Field measurements are performed along three driving routes used for testing within the urban environment in Ilorin, Kwara State, Nigeria, to obtain the strength values of radio signals received from three different transmitters. The transmitters propagate radio wave signals at 89.3 MHz, 103.5 MHz, and 203.25 MHz, respectively. A simple five-layer optimized ANFIS network structure is trained based on the back-propagation gradient descent algorithm so that given values of input variables (distance and frequency) are correctly mapped to corresponding path loss values. The adoption of the Pi membership function ensures better stability and faster convergence at minimum epoch. The developed ANFIS-based path loss model produced a low prediction error with Root Mean Square Error (RMSE), Standard Deviation Error (SDE), and correlation coefficient (R) values of 4.45 dB, 4.47 dB, and 0.92 respectively. When the ANFIS-based model was deployed for path loss predictions in a different but similar propagation scenario, it demonstrated a good generalization ability with RMSE, SDE, and R values of 4.46 dB, 4.49 dB, and 0.91, respectively. In conclusion, the proposed ANFIS-based path loss model offers desirable advantages in terms of simplicity, high prediction accuracy, and good generalization ability, all of them critical features for radio coverage estimation and interference feasibility studies during multi-transmitter radio network planning in the VHF bands. Keywords: Path loss models, Adaptive Neuro-Fuzzy Inference System, Neural network, Radio wave propagation

Path loss models are essential in the planning of wireless networks. However, the peculiar ambient characteristics of geographical locations necessitate a wide range of these models to take into consideration the different terrain dielectric, scattering irregularities, and clutter. This study investigates the effects of terrain and clutter on frequency-dependent path loss models in the very high frequency (VHF) and ultra high frequency (UHF) bands using multi-transmitter scenarios. Seven transmitters and 15 measurement routes were covered using an Agilent N9342C spectrum analyser. The measured results show that the models' prediction errors (PEs) follow the terrain profile and also that the clutter effects are noticeable along each route with varying degrees of impact. Near constant standard deviation errors (SDEs) were observed across all the models for the specific routes as well as a strong dependency on the terrain profile and clutters along the measurement routes. The UHF and VHF bands have average SDEs of 10.5 and 7.5 dB, respectively. A three-dimensional digital elevation model (DEM) showing the terrain and PE was also developed. Contour lines were extracted from the advanced spaceborne thermal emission radiometer and global DEM data sets. Visualisation of the terrain profile was achieved in the ArcScene software environment.

Over the years, the overdependence on Wireless Fidelity (Wi-Fi) for data transmission necessitated the need for an alternate and more reliable means of communication, hence, Light Fidelity (Li-Fi). It involves the use of Light Emitting Diode to transmit data by blinking (i.e. switching them On and Off) at a speed not noticeable to the eye. This paper proposed the development of the Li-Fi system using off the shelf electronic components. The proposed system utilizes an embedded system with dual-core Advanced Virtual RISC (AVR) microcontroller (ATmega16L) interfaced to input/output circuits comprising of the Light Emitting Diode (LED), LM358N Operational Amplifier and a photodiode. Also, by developing a user (Receiver PC) interface using JAVA programming, the sample data (text) transferred was monitored and the speed, efficiency, security and capacity of the system was examined and discovered to be top notch. This would make the system an indispensable means of communication in the nearest future. This data transmission system is different from those in existence because expensive components were not in the design, invariably reducing the overall cost of the implementation.

In recent years, we have witnessed a paradigm shift in mobile operator deployment from Long Term Evolution Advanced (LTE-A) to fifth generation (5G) networks. With the completion of the 3GPP Release 15 standards supporting “Non-Standalone 5G” in late 2018, attention has shifted to Standalone 5G, whilst operators across the globe continue to accelerate deployment of 5G based on the latest specifications. This paper addresses the global trends and challenges for early 5G rollout with focus on the Nigeria market. It also provides solutions to guide Nigerian mobile operator on pitfalls and barriers to entry, to allow smooth transitioning from 4G to 5G technology in Nigeria. Finally, the paper provides empirical evidence suggesting UE connected to the small cells use lower transmit power, hence improving uplink performance.

Artificial Neural Networks (ANNs) which are one of the main tools used in machine learning have often been utilised in developing models for path loss modelling in recent times. However, the ANN algorithm that provides the best results has not been well established neither has the models been characterized to limit their performances and applications in the various frequency bands. In this paper, we characterize the propagation loss in the Very High Frequency Band (VHF, 30-300MHz) by using different ANN learning algorithms and activation functions based on the measurement data collected at 203.25 MHz in an urban environment (Ilorin, Nigeria). Prediction results of Hata, ECC-33, Egli and COST 231 propagation models at varying distances were fed into a feed-forward neural network and mapped to each corresponding measured path loss value. Statistical analysis shows that the ANN model that was trained with hyperbolic tangent activation function (HTAF), Levenberg-Marquardt (LM) algorithm, and 80 neurons in the hidden layer produced the most satisfactory results with Mean Error (ME), Root Mean Square Error (RMSE), Standard Deviation (SD), and coefficient of determination (R^2) values of 3.75 dB, 5.10 dB, 3.46 dB, and 0.95. However, the HTAF with Scale Conjugate Gradient (SCG) is more stable even though its prediction errors were slightly higher than that of LM.

[EN] Deep knowledge of how radio waves behave in a practical wireless channel is required for effective planning and deployment of radio access networks in urban environments. Empirical propagation models are popular for their simplicity, but they are prone to introduce high prediction errors. Different heuristic methods and geospatial approaches have been developed to further reduce path loss prediction error. However, the efficacy of these new techniques in built-up areas should be experimentally verified. In this paper, the efficiencies of empirical, heuristic, and geospatial methods for signal fading predictions in the very high frequency (VHF) and ultra-high frequency (UHF) bands in typical urban environments are evaluated and analyzed. Electromagnetic field strength measurements are performed at different test locations within four selected cities in Nigeria. The data collected are used to develop path loss models based on artificial neural network (ANN), adaptive neuro-fuzzy inference system (ANFIS), and Kriging techniques. The prediction results of the developed models are compared with those of selected empirical models and field measured data. Apart from Egli and ECC-33, the root mean squared error (RMSE) produced by all other models under investigation are considered acceptable. Specifically, the ANN and ANFIS models yielded the lowest prediction errors. However, the empirical models have the lowest standard deviation errors across all the bands. The findings of this study will help radio network engineers to achieve efficient radio coverage estimation; determine the optimal base station location; make a proper frequency allocation; select the most suitable antenna; and perform interference feasibility studies., This work was supported jointly by the funding received from IoT-Enabled Smart and Connected Communities (SmartCU) Research Cluster and the Center for Research, Innovation and Discovery (CUCRID) of Covenant University, Ota, Nigeria.

Deployment of heterogeneous networks (HetNets) is a veritable solution to the challenges of coverage and capacity in meeting the unprecedented future mobile data traffic. However, the high density of small base stations (SBS) in future HetNets may increase the complexity of backhauling with higher capital expenditure (CAPEX), operating expenditure (OPEX), and energy cost. In this paper, a comprehensive review of various backhauling options for future HetNet is provided. For a HetNet system of seven SBS scenario, the efficiencies of the backhauling technologies are evaluated based on power consumption analysis. The implementation of energy-efficient microwave communication links is also considered based on realistic power consumption. Findings show that massive MIMO (M-MIMO) backhauling system consumes the highest power at maximum load. Power consumption in M-MIMO tends to rise as the number of transmitting antennas increases. In the same vein, power consumption in self-backhauling is relatively high when compared with conventional backhauling systems such as the microwave point-to-point (P2P) and point-to-multipoint (P2MP). On the other hand, total power consumed by satellite hub site, fiber optics, and cloud radio access network (CRAN) technologies are found to be relatively low (271.0571, 96.8083 and 90.1920 W, respectively). Fiber optics, CRAN, satellite hub site, and P2MP backhauling options proved to be more energy efficient in a decreasing order, when coverage and capacity are considered. The contribution of this work will help mobile network operators (MNO) in better decision making toward achieving a sustainable backhauling in future HetNet deployments.

This work presents the design and model implementation of a novel home automation system applying the Internet of Things (IoT) technology. It seeks simplified design protocols for developing a robust home automation system to deal with the problems of complexity, multiple incompatible standards and the resulting expenses in the existing systems. The embedded system features the ubiquitous low-cost 32-bit ESP8266 System-on-chip (SoC) module interfaced to some sensors and actuators for interaction in the home. Flexibility in the remote access, operation and management is achieved through HTML5 based intuitive mobile and web GUI applications. Web Application Messaging Protocol (WAMP) is deployed to ensure that individual applications and systems seamlessly communicate with a relatively high level of security using robust web service security protocol. This system offers a cost-effective and efficient solution, because the costs of a dedicated public IP address and a high-end computer are excluded, which are present mostly in other solutions.

Access to quality healthcare is a major problem in Sub-Saharan Africa with a doctor-to-patient ratio as high as 1:50,000 which is far above the recommended ratio of the World Health Organization (WHO). This has been aggravated by the lack of access to critical infrastructures such as the health care facilities, roads, electricity and many others. Even if these infrastructures are provided, the number of medical practitioners to cater for the growing population of these countries is not sufficient. However, the growing impacts of telemedicine have shown some positive effects in the healthcare delivery system, particularly in developing countries. Therefore, this paper shows how Information and Communication Technology (ICT) can be used to drive a sustainable and veritable health care delivery system through the introduction and promotion of Virtual Clinics and integration of various health information systems such as Electronic/Mobile Health and Electronic Health Record systems into the healthcare industry in Sub-Saharan Africa. Having identified implementation challenges as a major problem to the success of e-Health initiatives, the paper suggests ways of attaining successful implementation of telemedicine applications or services and remote health care facilities. Furthermore, research directions for the successful implementation and integration of the Virtual Clinic systems are provided.

The introduction of new kinds of technological products, applications and services that rely on wireless communications has resulted into an upsurge inglobal mobile data traffic. There is, therefore, a need to investigate the efficient utilization of the limited available radio spectrum. In this paper, we examine the spatial variation of spectrum occupancy (i.e. duty cycle) in the GSM 900 MHz band within Kwara State, Nigeria. Experimental results show that there is a very high spatial variance in duty cycle from one location to the other with mean occupancies of 1.67% and 17.76% in rural and urban locations respectively. It is worthy to mention that some rural locations recorded 0% duty cycle. Therefore, the telecommunication industry in Nigeria should adopt useful techniques to maximize the scarce radio resources, especially for rural areas.

Explosion in the demand for mobile applications and services necessitates the efficient utilization of the limited radio spectrum. Determination of a suitable detection threshold is an important aspect of spectrum occupancy measurement. Inappropriate choice of the threshold value may either increase the probability of false alarm or failure detection. However, the most appropriate threshold value is not yet clearly stated, though, the International Telecommunication Union (ITU) has provided a benchmark of 10 dB above the noise level as an acceptable threshold value. In this paper, the effects of energy detection threshold techniques on duty cycle in the GSM bands are examined. Spectrum measurements were conducted in the GSM 900 and 1800 MHz bands in Ilorin, Nigeria to cover a bandwidth of 105 MHz. Experimental results based on analytical method of determining noise level (theoretical) and those obtained based on actual measurements of the noise floor (measured) were analyzed. Findings indicated that the MaxNoise overestimates the occupancy values across all bands while the ITU 10 dB was found to be too conservative. Therefore, for optimum prediction, 5 dB above the measured average noise level should be considered as detection threshold. Furthermore, it was found that the number of frames of the sensing data do not have significant effect on the duty cycle.

Empirical path loss propagation models are widely used for coverage planning and interference analysis of wireless networks. The efficacy of these models depend on the local ambient features of the environments, thus, making them susceptible to high prediction errors when applied in different set of environments. In this paper, we developed a Kriging model for path loss prediction in the Very High Frequency (VHF) band using a geo-statistical approach. Electromagnetic field strength measurements were conducted in the VHF band (i.e. 203.25 MHz) in Ilorin metropolis, Nigeria. The predictions of the proposed model were compared with the already established empirical models. The standard and widely used models that are considered include Hata, COST 231, Egli and ECC-33 models. The performance of each model was adjudged based on the Root Mean Squared Error (RMSE). Results show that across all the distinct routes, the empirical models tend to over-and under estimate path losses while the developed Kriging model recorded the lowest prediction errors. The deployment of Kriging, ECC-33, Hata, COST 231 and Egli models produce an average RMSE of 5.653 dB, 9.351 dB, 14.267 dB, and 18.040 dB dB respectively.

Path loss prediction models are essential in the planning of wireless systems, particularly in build-up environments. However, the efficacies of the models depend on the local ambient characteristics of the environments. This paper proposed the Neuro-Fuzzy (NF) model for path loss prediction for Ilorin in the VHF band. Received signal strengths along four different routes were measured using NTA Ilorin transmitter which operates at a frequency of 203.25 MHz as a reference. The predictions of the proposed model was compared to Hata, COST 231, Egli and ECC-33 models which are considered standard and widely used empirical path loss models. The Root Mean Square Error (RMSE) was used as a measure of merit for their performances. Across all the routes visited, an average RMSE of 5.253 dB, 9.487 dB, 14.264 dB, 18.696 dB, and 27.890 dB were obtained respectively for the NF, ECC-33, Hata, COST 231 and Egli models. The NF model result is shown to improve the predictions over the estimates obtained when compared with the other models.

The spectrum sharing between primary TV systems (Channels 9 and 35) and Public Safety Networks (PSNs) is presented in this article. The networks to be deployed within Television White Space (TVWS) in Ilorin metropolis of Kwara State operate on a secondary basis spatially, without causing harmful interference to incumbent TV users. In order to guarantee the protection of incumbent TV users both in VHF and UHF bands, minimum separation distances were suggested considering field strengths of 36 dBu and 41 dBu as the protected contours for the two bands respectively. The effects of varying the transmit power and the antenna height of the secondary system on the coverage area are emphasized in this work. Aggregate interference effect from the multiple secondary systems on the TV service coverage was also investigated. The performances of VHF and UHF bands were also verified when used for secondary transmission both at lower and higher transmit power scenarios. The results of this work show that the safety networks can co-exist with the TV systems without causing harmful interference with the suggested separation distances at the edge of the noise-limited service area, where the signal-to-noise ratio is 16 dB as recommended by the International Telecommunication Union-Radio sector (ITU-R). Keywords : PSN, TV systems, Signal-to-Noise Ratio, TV White Space, Service coverage.

In this work, the performance of eight prominent empirical path loss models and a localized model, in predicting path losses in build up areas is investigated. Multi-transmitter electromagnetic field strength measurements were conducted, using a dedicated Agilent spectrum analyzer, along five predefined routes in Osun State, Nigeria. The measured data were compared with the model predictions. Path profile and terrain undulations effects have been observed on the received signal. For all the routes and transmitters, Okumura, SUI models over predicted the path losses, while Ericsson model under predicted the losses. However, Hata, Davidson, Cost 231 and ILORIN models generally show promising results with varying performance. The average mean error values of 55.11 dB, -8.53 dB, 46.72 dB, -9.81 dB, -28.16 dB, -8.93 dB, -30.59 dB, -22.95 dB and -12.57 dB are respectively obtained for NTAOSOGBO transmitter for Okumra, Hata, SUI, Cost 231, CCIR, Davidson, Ericsson, EEC-33 and ILORIN models. In terms of RMSE, the average RMSE values of 9.24 dB, 9.08 dB and 9.18 dB were obtained for ILORIN, Hata and Davidson models respectively. This trend was found to be similar for other transmitters i.e. OSBC, NDTV and NTA Ile Ife with varying performances among the four contending models. We, further, examined the route performance for the two main contending models i.e. ILORIN and Hata models. Inconsistency in terms of the performance for each model were observed, however the localized model i.e. ILORIN was found to provide optimum path loss prediction with considerable accuracy, over the other models. With the aforementioned, we believe the results and observations presented would provide guide to radio system engineers in making informed choices on the applicability and predictability of such models in the terrain of Osun State and other similar build-up areas in Nigeria.

In this paper, we propose a genetic algorithm (GA) based equalization approach for direct sequence ultra-wideband (DS-UWB) wireless communication systems, where the GA is combined with a RAKE receiver to combat the inter-symbol interference (ISI) due to the frequency selective nature of UWB channels for high data rate transmission. The proposed GA based equalizer outperforms significantly the RAKE and the RAKE-minimum mean square error (MMSE) receivers according to results obtained from intensive simulation work. The RAKE-GA receiver also provides bit-error-rate (BER) performance very close to that of the optimal RAKE-maximum likelihood detection (MLD) approach, while offering a much lower computational complexity.

In this work, signal path loss prediction from nine different empirical path loss models were statistically compared with those measured from four television transmitters along five routes that span through urban and rural environments of Osun State, Nigeria. In this respect, results obtained show that both Hata and Davidson prediction models provide best fit prediction consistently along the five measurement routes with 90% to 98% prediction accuracy, Ilorin, CCIR, Cost 231, Ericsson 9999 and ECC-33 show prediction accuracy within the range of 65% to 80% while SUI and Okumura models offer prediction accuracy within the range of 15% to 21%. Generally the results show that Davidson and Hata models have better results in all the five routes examined. SUI and Okumura models show the least performance results.

In this work, a genetic algorithm (GA) based frequency domain equalization (FDE-GA) scheme was proposed for direct sequence ultra wideband (DS-UWB) wireless communication systems. The proposed FDE-GA scheme does not require a guard interval (GI) and the output of the RAKE receiver is used as the input to our GA. The scheme achieved much higher bandwidth efficiency than conventional FDE methods because of the removal of the inter block interference (IBI) within each block before the GA. The FDE-GA receiver was shown to significantly outperform the RAKE receiver and the RAKE-GA receiver proposed in a previous work, in terms of bit error rate (BER) at a similar complexity. An improvement in the mean square error (MSE) was observed from simulation results presented, as a result of increase in the number of pilot symbols.Keywords: frequency domain equalization, guard interval, ultra-wideband, genetic algorithm, inter block-interference

Summary The huge amount of funds invested in deployment and installations of global satellite mobile infrastructures in Nigeria does not justify the poor quality of service (QoS) and network coverage experienced by the users in some areas while it is a gloomy issue as most of these infrastructures are grossly underused in other areas. The problem is majorly subjective to inappropriate location of the base transceiver stations (BTSs); hence, this work studied and analyzed an existing BTSs layout and proposes a model based on the use of median rule with rectilinear distance single facility location for appropriate deployment location of a new BTS that will ensure proper network connectivity and management of QoS for a given area. The case study is the University of Ilorin academic environment where transmission environmental monitoring system equipment was used to monitor the signals on the existing BTSs, to ascertain the positions of the existing BTSs, the total number of the existing BTSs, and areas of poor signal strengths for all the existing operators. The electric field intensity of each of the BTS sites was determined and was used as the weight in the rectilinear distance location model. The operator with the poorest signal strength was selected to occupy the new BTS so as to improve its handover and network connectivity.

This research is focused on evaluating the amount of television white space (TVWS) in the UHF band in Nigeria. The work takes a new perspective called the Geo-spatial approach in quantifying the available TVWS. Spectrum sharing model was developed from the protection viewpoint where the secondary users (SUs) are only allowed to reuse the spectrum outside the keep-out distance from the broadcast transmission grade B contour of the primary users. The spatial data used include the administrative map of Nigeria showing the states' boundary delineation and parameters for all the TV transmitters, including their coordinates. The broadcast range of transmission and protection contour of each UHF transmitter in Nigeria was obtained using the developed models. To show the broadcast range, the transmitter position, represented by a point, was subjected to GIS Buffering operation using the Analysis Tools extension within the ArcGIS ArcToolbox. Results obtained show that the proposed method recovers more white spaces when compared with the traditional command-and-control spectrum model. The work also provides the channel occupancy distribution of Nigeria, United Kingdom and the USA for the purpose of comparison.

In this Letter, the authors propose a technique that allows a secondary user (SU) to reuse the spectrum allocated to TV broadcast system. The approach is based on protection view point and an SU is allowed to transmit outside the noise limited contour (grade B contour) with additional protection margin. An algorithm was developed that predicts the grade B contour and makes a decision on the availability of the spectrum. The keep-out distance was obtained using the existing path loss models and a model developed based on field strength measure- ments conducted in the very high frequency (VHF) and ultra high frequency (UHF) broadcast frequencies. Results of simulation indicate that the extra margin does not follow a linear curve as expected, but strongly depends on the operating frequency and terrain profile of the area. In addition, the measured model's prediction deviates significantly from the other models' prediction.

In this work, a genetic algorithm (GA) based frequency domain equalization (FDE) scheme referred to as FDE-GA, which does not require any guard interval (GI),is proposed for direct sequence-ultra wideband (DS-UWB) wireless communication systems and is shown to significantly outperform the RAKE receiver. The proposed FDE-GA receiver also has a dramatic complexity reduction over the previous RAKE-GA receiver, while achieving a comparable bit error rate (BER) performance. The FDE-GA structure achieves a much higher bandwidth efficiency than conventional FDE methods, because the inter-block-interference (IBI), as a result of the absence of the GI, is removed effectively within each block before the GA.

We propose a genetic algorithm (GA) based equalization approach for direct sequence Ultra-wideband (DS-UWB) wireless communications, where GA is combined with a RAKE receiver to combat the inter-symbol interference (ISI) due to the frequency selective nature of UWB channels for high data rate transmission. Simulation results show that the proposed GA based structure significantly outperforms the RAKE receiver. It also provides a close bit error rate (BER) performance to the optimal maximum likelihood detection (MLD) approach, while requiring a much lower computational complexity.

The genetic algorithm (GA) is a well studied technique, which can obtain efficiently a near-optimal solution with much lower computational complexity compared to the maximum likelihood detection (MLD) approach. In overloaded MIMO systems, since the number of near equal-power co-channel interferers is higher than the number of receive antennas, the interference cannot be completely removed by spatial filtering. In this paper, we propose a new GA based detection approach for overloaded MIMO systems, whereby proportional scaling and Gaussian mutation is employed with a hybrid function to achieve a better performance than rank scaling and uniform mutation in the previous work. Simulation results show that our proposed approach not only significantly outperforms the zero-forcing (ZF) and minimum mean square error (MMSE) approaches and has much lower error floor, but also provides a performance which is close to the MLD with huge symbolic and numerical complexities reduction.

Path-loss model is essential for proper planning of emerging technologies in the broadcast frequency band. Characterisation of the radio channel is paramount for accurate prediction of TV coverage, and achievement of peaceful coexistence between the TV (primary users) and other new infrastructures (secondary users). In this paper, field strength measurements are conducted along six routes that spanned through urban, suburban and rural areas of Kwara State, Nigeria. The measurement results are compared with path-loss prediction of eight widely used empirical models. Least squares and linear iterative methods are employed to optimise Hata-Davidson's model, as it showed best fit compared with other models. The predictions of the tuned model are compared with other models in terms of relative error, mean error, skewness, root mean square errors and normalised error probability density function. Results of the simulations indicate that the optimised model gives better values for the metrics considered.