Research On Resource Allocation Algorithms Of Energy Harvesting Relay Network Based On SWIPT

With the development of mobile communication technology,the number of terminals increases sharply,which brings great pressure to the system capacity of communication network and the life of battery.Cooperative relay technology can not only improve the coverage rate of the system but also reduce the energy consumption of the system transmitter,so as to solve the problem of weak signal and low transmission power of marginal users.In the energy acquisition system,the communication node can continuously collect energy from the surrounding environment,which provides a way to solve the energy consumption problem of the system equipment.The combination of energy acquisition technology and cooperative relay technology can solve the problem of user communication and energy supply,which has become the key technology of the next generation mobile communication system.In this thesis,the problem of charging and information transmission of stranded user terminals in disaster scenarios is taken as the research object.SWIPT is used by the surrounding user terminals to charge the stranded user terminals and forward their information to the base station as a relay.An optimization algorithm of resource allocation in energy acquisition relay network based on SWIPT is proposed.The system throughput and energy efficiency of the algorithm are analyzed theoretically and by simulation.The main research contents and innovations of this paper are as follows:(1)Aiming at the problem of charging and uplink information transmission of trapped user terminals in disaster scenarios,An optimization algorithm for energy harvesting and information transmission time allocation of SWIPT based on relay is proposed.The trapped user in the relay system is the source node,and the surrounding user terminals use SWIPT to charge it and forward the trapped user’s information to the base station as a relay.Under the constraint of harvested energy,the optimization problem of system transmission rate maximization is established.By analyzing the dual correlation of two-hop transmission and simplifying the objective function expression with Lambert W function,the optimal ratio of energy harvesting time to the total time and the optimal ratio of the first and second information transmission time of the relay system are obtained.Simulation results show that the proposed algorithm can provide energy for trapped users and improve data transmission rate.(2)Aiming at the problems of terminal charging and bidirectional communication for trapped users in disaster scenarios,a relay cooperative bidirectional transmission method based on SWIPT energy harvesting is proposed.In this method,the trapped user is the source node in the relay system,and the neighboring users are randomly distributed between it and the base station and act as the relay node for the communication between trapped user and the base station.SWIPT-TS mode is used to charge the trapped user.Under the constraint of the harvested energy by the trapped user and the down-link rate,the optimization problem of the maximum uplink reachable rate of the system is established.By analyzing the duality of two-hop transmission and using the Lambert W function,a relay selection and time allocation algorithm based on the maximum uplink reachable rate of the system was proposed.The simulation results show that the proposed algorithm improves the uplink data transmission rate while guaranteeing the down-link rate of the trapped user.(3)Aiming at the problem of communication between multiple trapped user terminals and the outside world in disaster scenario,a multi-user energy harvesting and relay transmission method based on SWIPT is proposed.There are multiple trapped users in the system of this method.Nearby users randomly distributed between the trapped users and the base station adopt wireless charging for the trapped users,and serve as relay nodes to help the trapped users communicate with the base station.Under the constraint of harvested energy,the optimization problem of the maximum rate of the system is established,and the optimization problem is solved by the max-min relay selection algorithm and the golden section search method.Simulation results show that the proposed algorithm can provide energy for the trapped user and ensure the communication between the trapped user and the outside world.