| As wireless communication technology develops,the high demands for network performance have resulted in a large amount of energy consumption.How to achieve green communication has become one of the challenges in future wireless communication.Reconfigurable Intelligent Surface(RIS)has the advantages of low cost and low power consumption,which can effectively improve network quality and reduce network energy consumption.Due to the strong coupling objective function and multiple constraints in the optimization problem of RIS assisted networks,it is difficult to solve the optimization problem of RIS assisted networks.This article focuses on the scenario of RIS assisted downlink multiple input single output(MISO)communication systems,jointly optimizing the active beamforming of base station and RIS phase shifting,aiming to propose effective solutions to improve the energy efficiency(EE)of the communication system.The main research content of this article includes:1.For the scenario of multiple irregular RIS assisted single user MISO systems,an optimization problem is established with the goal of maximizing system energy efficiency,combining RIS switches,active beamforming of base station,RIS phase shifting,and feasible position selection of RIS components.In order to solve the highly non convexity of the optimization problem,the established optimization problem is decomposed into three sub problems,and the solution of the optimization problem is obtained through an iterative algorithm based on alternating optimization.Finally,the system performance corresponding to different schemes is compared and the effect of several parameters on the system performance is analyzed.2.For the scenario of a single RIS assisted multiuser MISO system,an optimization problem with the goal of maximizing system energy efficiency is established,and an iterative optimization algorithm for jointly optimizing of RIS phase shifts and active beamforming of base station is proposed.The simulation shows that the proposed algorithm further improves the energy efficiency and spectral efficiency of the system. |
