Computation Efficiency For Secure UAV-enabled Mobile Edge Computing Networks

With the development of information technology,the demand for communication technology,including communication rate and communication delay,puts forward higher requirements.In such a scene,unmanned aerial vehicle(UAV)technology has received widespread attention.Due to the maneuverability and deployment flexibility of UAVs,in some relatively poor communication environments,such as mountainous areas,disaster areas,etc.,it can provide powerful communication assistance.Compared with the ground environment,the obstructions in the air are significantly reduced,so the air-to-ground channel can be assumed to be dominated by the line of sight(Lo S)channel.Since terminal equipment is usually affected by computing power,battery capacity,and delay requirements,the effect of computing large data is relatively poor.At this time,a widely used technology is mobile edge computing(MEC)technology.MEC has emerged as a promising technique to enhance the computation capacity and energy efficiency of wireless devices,for enabling various computation-intensive and latency-critical Internet-of-Things(Io T)applications.By deploying MEC servers at the network edge,terminal equipment can wirelessly offload the computation-heavy tasks for efficient remote execution to meet stringent delay requirements.UAV-enabled MEC architecture has been proposed by integrating UAV into MEC networks.This technology can be flexibly deployed in most scenarios even in wilderness,desert,and complex terrains,where the terrestrial MEC networks may not be conveniently and reliably established.Despite these benefits,the UAV-enabled MEC networks introduce new communication security problems due to the broadcast nature of wireless communications.The tremendous popularity of wireless medium for communications is mainly because of its broadcast nature,which allows access to multimedia and information without restriction on the user's location.However,guaranteeing secure communication in a wireless medium is made difficult by the same broadcast nature,which makes it easy to eavesdrop on an ongoing communication,while making it difficult to detect eavesdropping.Fortunately,the same physical properties,which have a detrimental effect on reliability in communication,provide an opportunity to enhance the secrecy of communication,if used carefully.For the success of UAV-enabled MEC,it is crucial to keep the confidentiality of the task offloading against eavesdropping attacks.Physical layer security has emerged as a viable solution to ensure perfectly secured wireless communications against eavesdropping attacks.The breakthrough concept behind wireless physical layer security is to exploit the characteristics of the wireless channel,such as noise,to provide secrecy for wireless transmissions.Although,security is conventionally viewed as a higher layer communication protocol stack design problem that can be tackled by using cryptographic methods,physical layer security has emerged as a promising alternative way of defense to realize secrecy in wireless communication.A key design metric that has been widely adopted in physical layer security is the secrecy rate,at which confidential message can be reliably transmitted without having the eavesdropper infer any information about the message.In this thesis,we focus on maximizing computation efficiency for secure UAV-enabled MEC communication system,in which the ground terminal device transmits the computing task to a fixed-height UAV,and potential eavesdroppers on the ground may eavesdrop on this communication process.We propose to employ the physical layer security to secure the communication process in UAV-enabled MEC.The main work of the UAV is to communicate with multiple ground users,meanwhile it should satisfy the quality and security via sending jamming signal to against the potential eavesdropper.Thus,the UAV is invoked as a source of jamming signals for imposing artificial noise on potential eavesdropper from interloping the communication.The UAV uses a full-duplex system,which can receive signals and send interference signals at the same time.We aim to maximize the secure computation efficiency,subject to the trajectory of the UAV,the minimum secret rate and the expected bits of tasks.We consider jointly optimizing the trajectory of the UAV and the transmission power of ground users.Since the original problem is non-convex and difficult to solve directly,we introduce a series of auxiliary variables and transform the original problem into an equivalent problem that is easier to handle.Finally,we propose a two-stage optimization algorithm for secure computation efficiency maximization based on the Lagrangian dual method.Simulation results show that our proposed algorithm has better performance than other benchmark algorithms.