Distributed denial of service (DDoS) attacks are a major threat to any network-based service provider. The ability of an attacker to harness the power of a lot of compromised devices to launch an attack makes it even more complex to handle. This complexity can increase even more when several attackers coordinate to launch an attack on one victim. Moreover, attackers these days do not need to be highly skilled to perpetrate an attack. Tools for orchestrating an attack can easily be found online and require little to no knowledge about attack scripts to initiate an attack. Studies have been done severally to develop defense mechanisms to detect and defend against DDoS attacks. As defense schemes are designed and developed, attackers are also on the move to evade these defense mechanisms and so there is a need for a continual study in developing defense mechanisms. This paper discusses the current DDoS defense mechanisms, their strengths and weaknesses.

The integration of Internet of Things devices onto the Blockchain implies an increase in the transactions that occur on the Blockchain, thus increasing the storage requirements. A solution approach is to leverage cloud resources for storing blocks within the chain. The paper, therefore, proposes two solutions to this problem. The first being an improved hybrid architecture design which uses containerization to create a side chain on a fog node for the devices connected to it and an Advanced Time-variant Multi-objective Particle Swarm Optimization Algorithm (AT-MOPSO) for determining the optimal number of blocks that should be transferred to the cloud for storage. This algorithm uses time-variant weights for the velocity of the particle swarm optimization and the non-dominated sorting and mutation schemes from NSGA-III. The proposed algorithm was compared with results from the original MOPSO algorithm, the Strength Pareto Evolutionary Algorithm (SPEA-II), and the Pareto Envelope-based Selection Algorithm with region-based selection (PESA-II), and NSGA-III. The proposed AT-MOPSO showed better results than the aforementioned MOPSO algorithms in cloud storage cost and query probability optimization. Importantly, AT-MOPSO achieved 52% energy efficiency compared to NSGA-III. To show how this algorithm can be applied to a real-world Blockchain system, the BISS industrial Blockchain architecture was adapted and modified to show how the AT-MOPSO can be used with existing Blockchain systems and the benefits it provides.

Digitization and automation have engulfed every scope and sphere of life. Internet of Things (IoT) has been the main enabler of the revolution. There still exist challenges in IoT that need to be addressed such as the limited address space for the increasing number of devices when using IPv4 and IPv6 as well as key security issues such as vulnerable access control mechanisms. Blockchain is a distributed ledger technology that has immense benefits such as enhanced security and traceability. Thus, blockchain can serve as a good foundation for applications based on transaction and interactions. IoT implementations and applications are by definition distributed. This means blockchain can help to solve most of the security vulnerabilities and traceability concerns of IoTs by using blockchain as a ledger that can keep track of how devices interact, in which state they are and how they transact with other IoT devices. IoT applications have been mainly implemented with technologies such as cloud and fog computing, and AI to help address some of its key challenges. The key implementation challenges and technical choices to consider in making a successful blockchain IoT (BIoT) project are clearly outlined in this paper. The security and privacy aspect of BIoT applications are also analyzed, and several relevant solutions to improve the scalability and throughput of such applications are proposed. The paper also reviews integration schemes and monitoring frameworks for BIoT applications. A hybrid blockchain IoT integration architecture that makes use of containerization is proposed.

In this study, we present a low-profile dual-spectrum split-ring monopole that operates at industrial, scientific and medical (ISM) (2.45 GHz) band and ultrawideband (UWB) spectrum (3.1–10.6 GHz). We optimised the design for dual-band operations by using circular split-ring radiators. The coupling between both rings drives the structure to achieve quasi-resonance frequencies in the UWB spectrum. A small stub combines the two radiators and both behave as a single element that enables the antenna to resonate at ISM band 2.45 GHz. The antenna achieves the desired characteristics in terms of good impedance matching, radiation properties as well as other physical and practical requirements such as compact geometry, planar profile and easy fabrication. The very good agreement between the simulated and measured results show that the proposed antenna has the potential for dual-band application.

In Ghana and many countries within Sub-Sahara Africa, Long Term Evolution (LTE) is being considered for use within the sectors of Governance, Energy distribution and transmission, Transport, Education and Health. Subscribers and Governments within the region have high expectations for these new networks and want to leverage the promised enhanced coverage and high data rates for development. Recent performance evaluations of deployed WiMAX networks in Ghana showed promising performance of a wireless broadband technology in supporting the capacity demands needed in the peculiar Sub-Saharan African terrain. The deployed WiMAX networks, however could not achieve the optimal quality of service required for providing a seamless wireless connectivity demands needed for emerging mobile applications. This paper evaluates the performance of some selected key network parameters of a newly deployed LTE network in the 2600 MHz band operating in the peculiar Sub-Saharan African terrain under varied MIMO Antenna Configurations. We adopted simulation and field measurement to aid us in our evaluation. Genex Unet has been used to simulate network coverage and throughput performance of 2X2, 4X4 and 8X8 MIMO configurations of the deployed networks. The average simulated throughput per sector of 4X4 MIMO configuration was seen to be better than the 2X2 configuration. However, the percentage coverage for users under the 2x2 MIMO simulation scenario was better than that of the adaptive 4x4 MIMO configuration with 2x2 MIMO achieving 60.41% of coverage area having throughput values between 1 -40Mbps as against 55.87% achieved by the 4x4 MIMO configuration in the peculiar deployment terrain.

Telemedicine has become an effective means of delivering quality healthcare in the world. Across the African continent, Telemedicine is increasingly being recognized as a way of improving access to quality healthcare. The use of technology to deliver quality healthcare has been demonstrated as an effective way of overcoming geographic barriers to healthcare in pilot Telemedicine projects in certain parts of Kumasi, Ghana. However because of poor network connectivity experienced in the pilot projects, the success of the pilot networks could not be extended to cover the whole city of Kumasi and other surrounding villages. Fortunately, recent deployment of WiMAX in Ghana has delivered higher data rates at longer distances with improved network connectivity. This paper examines the feasibility of using WiMAX in deploying a city wide Mobile Telemedicine solution. The network architecture and network parameter simulations of the proposed Mobile Telemedicine network using WiMAX are presented. Five WiMAX Base Stations have been suggested to give ubiquitous coverage to the proposed Mobile Telemedicine sites in the network using adaptive 4 × 4 MIMO antenna configurations.

Worldwide Interoperability for Microwave Access (WiMAX) technology has gained growing interest due to its applications and advantages. It is fast emerging as a last-mile problem solution for broadband access technology. This paper presents operation scenarios for the deployment of a Fourth Generation (4G) WiMAX system in a typical sub-Saharan African environment. This has been specified based on real world conditions considering the regulatory rules specified by the National Communication Authority (NCA) for radio frequency spectrum utilization in the 2.6GHz licensed band in Ghana. Appropriate propagation models and Network planning tools have been used to design the final radio network plan. Coverage prediction has been performed using Genex-U-Net to achieve the main aim of providing coverage in the predefined areas of Accra and Tema, Ghana. Simulation results for different downlink/uplink ratios with different frequency reuse schemes have been presented. A total of 11 base stations have been suggested to provide coverage of -92dBm using 32 sectors 4 transmit 4 receive (4T4R) adaptive Multi-Input Multi-Output (MIMO) antenna configuration within the Accra and Tema municipality. Finally the system performance is evaluated through field trial measurement and the results presented.

Lake Volta is the world's largest man-made lake by surface area, and the fourth largest by water volume. Located completely within Ghana, it has a surface area of about 8502 km 2 (3283 square miles). Like many other lakes on the African continent, Lake Volta is a major natural resource for Ghana, storing water for the operation of the hydroelectric dam, water supply for domestic, agricultural and industrial purposes, habitat for diverse aquatic species, an avenue for recreational activities, means of navigation between the north and south parts of the country, and a climate modulator for the tropical region. The lake has experienced variable water level and surface area changes attributable to climate change and excessive water abstractions. Using histogram thresholding techniques, this study produced binary images and vector maps of the lake. Spatial extent mapping of the lake using Landsat TM 1990, ETM + 2000 and ETM + 2007 images indicated the lake experienced both increased and decreased surface area changes during the study period. The lake's surface area varied by about 197 km 2 between 1990 and 2007, with the water level fluctuating between AE7 m. Factors thought to be contributing to these changes include human factors (regulated flows, deforestation, increased water abstractions and pollution) as well as natural phenomenon (climate change, water run-off and subsequent sediment transport).