Service Time-Aware Caching, Power Allocation, and 3D Trajectory Optimised Multimedia Content Delivery in UAV-Assisted IoT Networks

In this paper, we consider an integration of software-defined edge techniques into unmanned aerial vehicles (UAV) to deliver multimedia contents in Internet of Things (IoT) networks. The UAV is integrated with caching, resource allocation, multicasting transmission, and 3D flight trajectory (3DF) techniques, to serve the IoT devices and users (IDU) in different clusters. By further utilising many aspects of multimedia contents, IDU features, UAV-to-clusters association, and diverse characteristics of wireless propagation environments, we formulate a service time-aware caching, power allocation, and 3DF (TCP-3DF) optimisation problem. The TCP-3DF problem is solved by genetic algorithms (GA) for optimally finding 1) the multimedia contents to cache, 2) the powers allocated to multicast each content and to fly over each hop, and 3) where to stop in 3D coordinates and stop sequence. The optimal results are found under the constraints not only on the storage and power resources but also on the service time required by different multimedia applications and services. Due to the complexity of various optimisation variables and constraints, the GA is modified to ensure the accurate and stable convergence by applying penalty function and truncated chromosome scheme. Simulation results are shown to demonstrate the feasibility of GA and the benefits of the proposed TCP-3DF method in terms of sum rate, service time, and flight distance while conserving the storage and power resources.