Research On Power Control And Relay Selection For Optimizing Safety Performance Of Energy Harvesting Relay Network

The application of energy harvesting technology in communication networks is of great significance for reducing traditional energy consumption,environmental pollution and network operation costs.However,the amount of energy harvesting is random and the process of energy harvesting is still unstable and uncertain.Meantime,the wireless channel fading is also random,the energy management of the harvested energy is an important problem that affects the system performance,and the transmission power control is one of the main problems.For the secure transmission system,the energy arrival process and the channel fading process are stochastic and their statistical characteristics are unknown,the optimization problem of power control and relay selection is solved by using the Lyapunov optimization framework that only depends on the current system state.The main contents are as follows:1.In order to optimize the secrecy rate,the joint power control problem in a single-relay secure communication system where the source node and the relay are equipped with energy harvesting devices is studied.The system consists of a source node,a relay node and two destination nodes,and the information of the two destination nodes is confidential to each other.Firstly,the optimization problem is constructed as maximizing the long-term average secrecy rate under the available energy constraint.Then,based on the Lyapunov optimization framework,the optimization problem is transformed into a joint power control problem of two nodes,which maximizes the secrecy rate of a single slot while maintaining the virtual queue stable,and the solution of the problem is given.The algorithm is verified by simulation,and the simulation results show that compared with the greedy algorithm,the half power algorithm and the random power algorithm,the proposed algorithm can effectively improve the long term average achievable secrecy rate of the system,and the performance is better.2.In order to maximize the long-term averaged secrecy rate,the optimization problem of relay selection and the transmission power control of relays in multi-relay secure communication system with energy harvesting is studied.Both relays in the system are equipped with energy harvesting devices,and they can work in amplifying and forwarding mode or cooperative interfering mode.Firstly,the possible modes of relay can be determined according to the current channel state of the system.Then the optimization problem of the relay power control under the possible modes is constructed,and the optimizaition problem is transformed by using the Lyapunov optimization framework and solved.Finally,the optimal relay working mode and transmission power are determined.The algorithm is verified by simulation.The simulation results show that compared with the greedy algorithm,the half power algorithm and the random power algorithm,the proposed algorithm has effectiveness in improving the long term average secrecy rate of the system through the cooperation between two relay nodes and the optimization of transmission power.