Secrecy Energy Efficiency Optimization Of Uav Communication System

Due to its low cost,flexibility for deployment and high probabilities of line-of-sight(LoS)communication link,unmanned aerial vehicle(UAV)has become one of the important roles in non-terrestrial communication system and has been widely studied in recent years.However,there exist the security problems caused by the UAV line-of-sight link and the energy defects caused by the onboard battery with limited capacity,which introduce many challenges to UAV-enabled communication system.Therefore,this thesis studies the security and energy efficiency of the cooperative multi-UAV communication systems,and puts forward the optimization schemes to improve the performance of systems established according to the actual application scenarios.The main contents and innovations of this thesis are as follows:A secrecy energy efficiency optimization scheme of UAV multi-hop relay system based on LoS probability is proposed to solve the security issue in long-distance communication.A UAV-enabled multi-hop relay system with multiple eavesdroppers model is constructed,and a system secrecy energy efficiency maximization problem is established based on the LoS probability model.To solve the non-convex problem,a joint optimization algorithm based on block coordinate descent(BCD)algorithm is proposed to alternately optimize UAV’s trajectory and transmit power.By analyzing the system performance and comparing with other schemes,the effectiveness of the proposed joint optimization scheme is proved.A secrecy energy efficiency optimization scheme of cooperative jamming UAV multi-hop relay system is proposed to further improve the secrecy performance in long-distance communication scenarios.In the proposed system,some UAVs are deployed as relay to transmit confidential information,and the other UAVs send jamming signals to confuse the eavesdropping link.To improve the system secrecy energy efficiency performance,a four-stage iterative optimization algorithm based on BCD algorithm,successive convex approximation(SCA)algorithm and Dinkelbach algorithm is proposed to jointly optimize the trajectory and power of two types of UAV.Finally,the algorithm complexity and convergence are analyzed.The simulation results show that the cooperative jamming joint optimization scheme can significantly improve the system secrecy and energy efficiency compared with other schemes.A secrecy energy efficiency optimization scheme of multi-functional UAV-enabled mobile edge computing(MEC)system is proposed to solve the computing power and secure issue in Internet of things scenario.There are two UAVs in the MEC system,which are respectively responsible forauxiliary calculation or transmitting interference.To solve the non-convex problem,an efficient iterative algorithm is proposed.Finally,compared with other schemes,the effectiveness of proposed scheme is verified from the perspectives of system secrecy performance gain and energy efficiency.