Research On Optimization Of Resource Allocation In Wireless Powered Communication Network

With the development of 5G and the Internet of Things technology,more and more wireless devices are connected to the communication network,realizing the new era of the Internet of everything.But it also raises new questions.The high-density deployment of 5G network leads to the shortage of spectrum resources and the sharp increase of communication system energy consumption.Energy efficiency and cognitive radio can effectively solve the above two problems.In addition,because wireless devices are powered mainly by their own batteries,the battery capacity determines the working period of wireless devices,thus affecting the service life of the network.Therefore,in order to extend the service life of the network,RF energy harvesting technology can be adopted to effectively solve the power supply problem of wireless equipment through the use of renewable energy.However,the problem of "doubly-near-far" in wireless communication network research at the present based on energy harvesting technology make the user exist unfairness in the system,and will affect the performance of the entire communication system.Therefore,how to solve this problem becomes the key factor to optimize the performance of wireless powered communication network.This paper studies from the following two aspects respectively.In view of the Internet of Things scenario with the low power consumption,this paper makes a specific study on how to reduce the energy consumption of the communication system,improve the spectrum utilization and extend the network life from the following two aspects.In order to solve the problem of “doubly-near-far”,a user collaborative relay wireless powered communication network(UCR-WPCN)is studied in this paper.Our goals are to study the total energy efficiency(EE)maximization of users in UCR-WPCN by jointly optimizing time,power allocation and meet minimum rate requirements.However,because this problem is a non-convex,it is difficult for us to solve it.Then,we can use fractional programming principle theory and variable substitution to convert it into a standard convex optimization problem.Finally,we proposed an efficient optimization iterative algorithm in order to find the optimal solution.The simulation results show that the UCR plan can improve the user's information transmission rate and significantly improve the user's total energy efficiency in the system,compared with the non-cooperative relay transmission scheme.In view of the energy efficiency problem of the wireless powered communication network,the harvesting energy from a single RF is unable to effectively improve the energy efficiency of communication system.Thus,this paper proposes an energy harvesting model from more than one RF signal under the cognitive radio environment.Besides considering energy collection problem,the model also considers the problem of spectrum resource scarcity and low utilization of spectrum.Aiming at the special structure of the optimization problem,a method of optimizing time allocation,power control and optimization iterative algorithm is proposed in order to solve the problem of maximizing the system energy efficiency.The simulation results demonstrate the effectiveness of the model and the proposed algorithm and the obvious improvement of EE.