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SDN controllers are increasingly becoming an integral part of modern communication networks due to their ability to centrally control and manage networks from a global point of view. One of the application areas in which the SDN paradigm is gaining traction is the Integration of Satellite and Terrestrial Networks (ISTN). Considering that there are different SDN controllers with their intrinsic characteristics, which translate to different performance characteristics, it is pertinent to determine the SDN controllers that will be most suitable for the specific application area. This study embarked on evaluating selected SDN controllers that will help in making informed selection decisions for suitability in a future ISTN architecture. Five SDN controllers were subjected to evaluation and they are Open Network Operating System (ONOS), Opendaylight (ODL), Floodlight (FL), Ryu, and Pox. These controllers are evaluated based on throughput and latency metrics, which are considered some of the factors that could influence the performance of the interworking of both terrestrial and satellite networks. The controllers were subjected under various topologies and traffic densities which are (i) single topologies under no cross traffic, half-bandwidth cross traffic, and high-bandwidth cross traffic conditions (ii) linear topology under no cross traffic, half-bandwidth cross traffic, and high-bandwidth cross traffic conditions (iii) tree topology under no cross traffic, half-bandwidth cross traffic, and high-bandwidth cross traffic conditions (ii) linear topology under no cross traffic, half-bandwidth cross traffic, and high-bandwidth cross traffic conditions (iii) tree topology under no cross traffic, half-bandwidth cross traffic, and high-bandwidth cross traffic conditions. Under all conditions, ONOS shows superiority in terms of throughput while Ryu shows superiority in terms of synchronization time. Focusing specifically on the tree topologies, considering it follows the same pattern with the single and linear topologies, the ONOS exhibited throughput of 815flow/ms under no cross traffic and throughput of 807flow/ms under both half-bandwidth and high-bandwidth band cross traffic. Ryu exhibited a synchronisation time of 19ms, 23ms, and 26ms under the no cross traffic, half-bandwidth cross traffic, and high-bandwidth traffic cross-traffic conditions, respectively. Observing from the values for both the throughput and synchronisation time metrics under all the topologies, it can be inferred that a number of hosts have more impact on the metrics rather than traffic volume, and this could be attributed to caching mechanisms like Address Resolution Protocol (ARP) wherein new traffic from known hosts can quickly be processed compared to new traffic from new hosts. In summary, the ONOS controller can be considered to offer good performance in an ISTN.

SDN controllers are increasingly becoming an integral part of modern communication networks due to their ability to centrally control and manage networks from a global point of view. One of the application areas in which the SDN paradigm is gaining traction is the Integration of Satellite and Terrestrial Networks (ISTN). Considering that there are different SDN controllers with their intrinsic characteristics, which translate to different performance characteristics, it is pertinent to determine the SDN controllers that will be most suitable for the specific application area. This study embarked on evaluating selected SDN controllers that will help in making informed selection decisions for suitability in a future ISTN architecture. Five SDN controllers were subjected to evaluation and they are Open Network Operating System (ONOS), Opendaylight (ODL), Floodlight (FL), Ryu, and Pox. These controllers are evaluated based on throughput and latency metrics, which are considered some of the factors that could influence the performance of the interworking of both terrestrial and satellite networks. The controllers were subjected under various topologies and traffic densities which are (i) single topologies under no cross traffic, half-bandwidth cross traffic, and high-bandwidth cross traffic conditions (ii) linear topology under no cross traffic, half-bandwidth cross traffic, and high-bandwidth cross traffic conditions (iii) tree topology under no cross traffic, half-bandwidth cross traffic, and high-bandwidth cross traffic conditions (ii) linear topology under no cross traffic, half-bandwidth cross traffic, and high-bandwidth cross traffic conditions (iii) tree topology under no cross traffic, half-bandwidth cross traffic, and high-bandwidth cross traffic conditions. Under all conditions, ONOS shows superiority in terms of throughput while Ryu shows superiority in terms of synchronization time. Focusing specifically on the tree topologies, considering it follows the same pattern with the single and linear topologies, the ONOS exhibited throughput of 815flow/ms under no cross traffic and throughput of 807flow/ms under both half-bandwidth and high-bandwidth band cross traffic. Ryu exhibited a synchronisation time of 19ms, 23ms, and 26ms under the no cross traffic, half-bandwidth cross traffic, and high-bandwidth traffic cross-traffic conditions, respectively. Observing from the values for both the throughput and synchronisation time metrics under all the topologies, it can be inferred that a number of hosts have more impact on the metrics rather than traffic volume, and this could be attributed to caching mechanisms like Address Resolution Protocol (ARP) wherein new traffic from known hosts can quickly be processed compared to new traffic from new hosts. In summary, the ONOS controller can be considered to offer good performance in an ISTN.

This work presents an improved cuckoo search algorithm based on Success Rate (CSA-SR) for optimal allocation of Distributed Generation (DG). This is necessary in order to improve the power quality of the distribution system by minimizing power loss and improving voltage stability. Voltage Stability Index (VSI) is applied to identify restricted unhealthy buses/areas in the distribution networks. The work is implemented on standard IEEE 33 Bus test systems. Newton Raphson Power Flow (NRPF) technique is used in MATLAB R2019b environment for the power flow analysis. The overall IEEE 33 Bus system real power loss obtained from the simulation result is found to be 202.7071MW at the base case. Following the application of 3 DGs using CSA-SR, the real power loss is found to be 113.9630 MW which shows a reduction of 88.441MW which is equivalent to 43.77% as related to the base case. The results minimized the system losses while significantly enhancing the voltage profile of the bus voltages as a result of optimal siting and sizing of the DG. These show that the CSA-SR technique outperformed PSO, which was used to ascertain the effectiveness of the developed scheme.

Wireless body area networks (WBANs) assemble multiple transceiver nodes in, on, or around a patient's body to transmit physiological signals to the sink node and further send it to the medical personnel via a medical server. WBANs a sensor network that is characterized as energy-dependent. Due to this finite nature, the deployment of intelligent utilization is needed. Quality of service (QoS) is another area that needs rapt attention to receive exactly what was sent from the source node to the destination node and throughput. Critical data transmission is characterized by abnormal data status that requires an urgent response from the medical personnel without delay to save the patient's life. In this review article, we propose a review of critical data transmission in wireless body area networks. However, most past articles in this line focus more on energy-efficient, security and privacy, quality of the links, throughput, network maximization, and so on. None of them looks into the direction of transmitting critical data directly to the sink node without multi-hopping of the physiological signals between intermediate nodes, which wastes the time of transmission to save patient life. This disparity between these scholars motivates us to fill the gap between them. This review article briefly discussed the state-of-the-art critical data transmission in WBANs alongside the WBANs architecture and implementation. Furthermore, a pragmatic approach to determining the threshold's degree of critical data index sensed during transmission was also considered.

Wireless Body Area Networks (WBANs) are an integral part of a Wireless sensor network, where sensor nodes are strategically placed in the human body to sense physiological signals and transmit them to the medical personnel via server for medical observations. Every sensor node in WBANs has a general limitation in energy efficiency, end-to-end delay, residual energy, etc. Also, the high energy consumption in WBANs is mainly due to the number of hops covered during physiological signal transmission. This work developed a hop-distance scenario to address these challenges and improve on what others have done. It buffered traffic estimation schemes to minimize end-to-end delay and the total network energy efficiency. This work minimizes end-to-end delay dual-sink cluster-based routing in WBANs by improving the existing dual-sink-sink cluster-based scheme (iDSCB). The simulation result shows that the Minimization of end-to-end delay of the improved dual-sink cluster-based (iDSCB) enhanced the performance of the current article DSCB in terms of end-to-end delay and residual energy by 3.15% and 8.88%, respectively.

WBAN comprises multiple sensor nodes strategically located on patients' bodies. They collect physiological signals from a patient under medical observation and transmit them to the medical personnel for further analysis via a medical server. These sensor nodes are energy-dependent. The challenges associated with WBAN are the power source, delay, and so on. Since their energy source is derived from rechargeable batteries, it is impossible to stop the network operation to replace the battery. Past articles concentrated more on the problem of enhancing network delay and throughput. However, they did not look into the area of TDMA and CCA schemes to improve their work. This brings their work into network energy degradation, which reduces their throughput. This article implements Enhancing throughput cluster-based DSCB by improving the existing Dual-sink clustering approach (DSCB). The simulation result depicted that the Enhanced throughput of iDSCB improved the performance of the current work DSCB in terms of throughput and End-to-End Delay by 6.60% and 3.14%, respectively.