This paper addresses the problem of radio access technology (RAT) selection in heterogeneous networks (HetNets). Current approaches rely on signal related metrics such as signal to interference plus noise ratio (SINR) for selection of the best network for the wireless user. However, such approaches do not take into account the quality of service (QoS) requirements of wireless users and therefore often do not connect them to the most suitable network. We propose a QoS aware RAT selection framework for HetNets based on software-defined networking (SDN). The proposed framework implements a RAT selection strategy that reflects QoS requirements of downlink flows using a metric called fittingness factor (FF). The framework relies on the flexibility and centralised nature of SDN to implement monitoring and RAT capacity assessment mechanisms that help in the realisation of the selection strategy. The simulation campaign illustrates the important gains achieved by our RAT selection framework in terms of data rates assigned to the wireless users, their satisfaction, and their quality of experience (QoE) compared against other state of the art RAT selection solutions.

The energy consumption and coverage range of unmanned aerial vehicles (UAVs) are major challenges in UAV-based postdisaster communications. To address these challenges, energy harvesting is employed to power communication devices and prolong the lifetime of the wireless communication network during a disaster. In addition, clustering techniques and device-to-device (D2D) communication are needed to increase the overall network coverage and provide sustainable connectivity during the disaster and postdisaster phases. We have proposed a novel emergency communication system (ECS) using the optimal cluster head (CH) technique to improve the energy transfer efficiency for sustainable network connectivity. We have developed a UAV deployment model assisted by the clustering technique and D2D links that is capable of harvesting energy to increase the network lifetime. This new approach is expected to enhance the reliability of the network in disaster situations. The proposed methods have been evaluated by measuring the energy efficiency performance and the network outage probability. The simulation results demonstrate improved performance with the deployment of optimal CHs, while the outage probability has been effectively reduced. Moreover, the proposed approach has been proven to reduce the computational complexity. In conclusion, UAV deployment with the optimal CH algorithm is a suitable network design to recover from natural disasters and potentially save many lives.INDEX TERMS UAVs, energy harvesting, cluster heads, D2D communication, 5G.

During the past years, ubiquitous networks have become an interesting topic for research due to their flexible and independent nature in terms of network infrastructure. A lot of effort has been made around the design of efficient routing protocols, mainly because of their unique characteristics, such as, dynamic topology, high mobility and limited bandwidth. In this paper, we propose a new routing protocol which is based on our Multipath-ChaMeLeon (M-CML) routing protocol. We perform a network optimization analysis of M-CML under a series of simulations taking into account three Quality of Service (QoS) metrics and we provide the results with statistical confidence interval by applying the Wilcoxon signed-rank test model. On top of the outcome of the analysis, we also apply an intelligent algorithm to enhance our protocol's effectiveness by reducing the improvident emission of data packets. The new protocol, named M-CMLv2, is compared to OLSR, AOMDV and M-CML using the NS-3 simulator. The acquired results indicate that M-CMLv2 reduces the redundant information, maintains good performance at successfully delivering packets with acceptable end-to-end delay, while at the same time, it reduces the network's routing load and the energy consumption of the nodes.

The wireless communication is an integral part of the society, however, wireless network infrastructure may not fully function during post-disaster wireless network scenario in which we need wireless services even more than normal circumstances. In such post-disaster scenarios, the base stations (BS) could possibly be dysfunctional or overloaded by an excessive number of user calls or data, whereas user terminals are likely to be partially connected to or fully isolated from the BS radio signals. In this paper, we study the network behavior during the post-disaster when BSs undergo the thinning process due to the damage to the network infrastructure. During network recovery phase, we also study the network performance when new temporary BSs are distributed which will bring the network into BS superposition phase. Furthermore, Device-to-Device (D2D) assisted cellular communication helps to increase the link level network connectivity which is highly appreciated during postdisaster network scenario because the network coverage is more desirable than the network throughout in such cases. We also present the analytical study of D2D and cellular communication and show that it will effectively increase the network coverage which may ultimately save many lives during the golden hours of post-disaster phase.

Blockchain, Quality of Experience (QoE), and Video Streaming have all received much attention from both academia and industry so far, although they have not been jointly addressed for prospective applications yet. While the industry has already adopted blockchain-based video streaming platforms, other stakeholders, e.g., academia, government, regulators, and service providers, could contribute more to develop protocols, technologies, and standards to help grow this niche technology and support its implementation in media streaming applications. This paper reviews the current technologies, industrial advancements, and critically identifies the current research activities and future research opportunities.

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The emerging fifth generation (5G) communication network is gaining tremendous attention from mobile network operators, regulators, and academia due to the provisions of network densification, ultra-low latency and improved spectral and energy efficiencies. However, post-disaster emergency management system (EMS), which nowadays predominantly depends on the wireless communication infrastructure, is significantly lagging behind in terms of innovation, standards, and investments. Since 5G vision is the revolution of the telecommunication industry, provisions of efficiently handling EMS is expected to be distributed, autonomous, and resilient to the network vulnerabilities due to both man-made and natural disasters. In this paper, the 4G LTE approaches for typical post-disaster communication and their shortcomings will be discussed. We elaborate three typical post-disaster network scenarios when the network is congested, partly functional or completely isolated. The possible solution framework, for instance, Device-to-Device communication, drone-assisted communication, mobile ad hoc networks and Internet-of-Things, for post-disaster scenario will be discussed. Given that the spectrum allocation is critical for EMS, we assess the possible schemes for radio resource allocation specific for EMS in addition to the social responsibility of users in such critical situations. between source and destination terminals is relatively higher. Moreover, the intermediate users may need to sacrifice the scarce energy for others which are not an ideal situation during postdisaster. The proposed 5G framework should consider such cases while designing distributed, autonomous and resilient multihop communication for EMS in order to preserve and ensure reliable communication among users.2) Drone-assisted Communication: Drones, or UAVs, are able to significantly assist in postdisaster communication by acting as a flying BS as shown in Fig. 4. One of the advantages of implementing drones to replace dysfunctional BSs is that it is likely to exist direct line-of-sight communication between users and flying drones. This results in improvement on the channel propagation due to the low path-loss and minimum shadowing, which helps to improve the QoR required for emergency communication. Moreover, the drone trajectory can be optimized depending on the predicted traffic pattern and user distribution. The network of UAVs not only acts as a radio access network but also the backhaul network for D2D communication, MANETs and other isolated users. In a typical post-disaster scenarios, UAVs can be used as UAV-