Research On Joint Resource Optimization Of Unmanned Aerial Vehicle-assisted Wireless Networks

In order to ensure different service requiremen ts of network and relieve the load pressure of ground base stations,UAV with strong line-of-sight(Lo S)communication and flexible on-demand deployment can be used as aerial base stations(ABSs)or wireless relays to assist ground networks to enhance cove rage and short-term restoration of ground network facilities.However,UAV-assisted wireless communication still faces many challenges in secure communication and prolong network survival time.On the one hand,there are a large number of potential eavesdropping and jamming attacks in UAV-assisted wireless communication,the secure capacity of the network is still difficult to guara ntee.On the other hand,due to the limited energy of UAV,how to optimize the flight trajectory and improve the endurance of UAV and the network survival time also require further analysis.To this end,the thesis carries out the following work:First,the thesis introduces the physical layer security and flight trajectory optimization technology of UAV-assisted wireless communication,and analyzes the problems and deficiencies in the UAV communic ation network combined with existing research.The system model of UAV-assisted wireless network is analyzed based on considering secure communication and trajectory optimization.Secondly,the thesis analyzes a secure communication scenario of UAVassisted terrestrial wireless network,and adopts a method of joint ground users and legitimate UAV-friendly interference to reduce the risk of eavesdropping.In order to further improve the secure capacity of the network,this thesis proposes a security capacity maximization algorithm based on gradient descent and successive convex optimization techniques.Considering the limit ations of UAV’s energy and the resources of ground nodes,the algorit hm maximizes network secure capacity by jointly optimizing the legitimate UAV’s position and transmission power,task offloading ratio and node association indicators.The simulation results show that the algorithm proposed in this thesis can not only obtain better convergence,but also effectively improve the secure capacity of the network.Finally,the thesis also analyzes the energy consumption minimization problem in the scenario of UAV-assisted data collection.Considering the energy of UAV and ground Io T sensor nodes is limited,and the sensor nodes have different transmission rate requirements,this thesis proposes a joint UAV flight trajectory and node access energy optimization algorithm.This algorithm minimizes the energy consumption of sensing no des when the UAV’s energy is limited by jointly optimizing the sensing node access scheme and UAV’s flight trajectory.The simulation results show that the algorithm proposed in this thesis has a better effect of reducing the energy consumption of sensing nodes than the traditional UAV’s flight strategy based on ensuring tolerable computational complexity and good convergence.