Performance Evaluation And Analysis Of 6G Reconfigurable Intelligent Surface

The fifth generation mobile communication(5G)has achieved the goals of higher speed,lower latency,massive connectivity,super capacity and wide area coverage,but it also faces the problems of high hardware cost,high network complexity and high energy consumption.In the future,wireless networks hope to reduce costs,complexity and energy consumption while ensuring sustainable capacity growth and further improving coverage.In this context,the reconfigurable intelligent surface(RIS)technology stands out with its low cost,low power consumption,programmable and easy deployment.RIS is a programmable twodimensional thin-layer electromagnetic surface structure,which is composed of large-scale reflection units and control modules.By intelligently reconfiguring the electromagnetic parameters of the reflection unit,regulating the electromagnetic characteristics of the reflected beam,transforming the uncertain and uncontrollable wireless propagation environment into a manually reconfigurable signal space,adding new degrees of freedom for wireless signal transmission.At present,most of the relevant researches on RIS are related to theoretical algorithms,and lack of system-level simulation of network performance under the new network topology brought by RIS.Systemlevel simulation provides an evaluation of the overall network performance of the system,which is of great significance to the subsequent implementation of RIS technology and its application in engineering.From the system-level perspective,this thesis studies the relevant technologies of RIS,develops and constructs a system-level simulation platform that adapts to the hardware characteristics of RIS,and conducts system-level simulation and evaluation of network performance under various scenarios and schemes of RIS assisted wireless communication.First of all,this thesis builds the RIS system-level simulation platform,studies and establishes the RIS antenna model,large-scale channel model,phase shift model,signal interference model,and realizes the functions of RIS scatter distribution,channel initialization,user access,performance index calculation,etc.RIS antenna model realizes the characterization of"mirror reflection" in 0 phase static state and the characteristics of electromagnetic beam direction in dynamic state.The RIS large-scale channel model focuses on the path loss and large-scale fading,and realizes the calculation of user received signal strength for the two-hop transmission of RIS relay.Secondly,this thesis studies different deployment schemes of RIS.The significant gain of RIS auxiliary communication is verified.The effects of the number of RIS panels,the size of the array,the array spacing and the deployment position,orientation and down tilt angle of the RIS on the system gain performance are studied and analyzed.The potential interference introduced by the deployment of RIS and the impact of nonservice RIS on the signal quality are also discussed.The results show that RIS is deployed near the user,and the setting of orientation and dip angle makes the incident angle and exit angle of electromagnetic wave roughly equal and generally smaller,with higher performance gain.The system gain is proportional to the number of RIS panels and the size of the array.Moreover,due to the large size of RIS array and narrow beam,the probability of interference is small.However,the reflection of non-service RIS on the signal may lead to the degradation of signal quality.In addition,this thesis conducts simulation research and performance evaluation on three phase shifting schemes of RIS for user beamforming,beam-scanning and blind beamforming.Beamforming for users has the best gain.When the beam scanning interval is equal to the beam width,the gain of beam scanning is equal to that of beamforming for users.Blind beamforming has a great improvement in the performance of fixed points in a relatively static environment.In addition,this thesis analyzes the impact of reflection phase quantization on the performance when studying the beam shaping of RIS for users.In the system simulation,the performance loss of 2bit quantization is about 0.37dB.Finally,this thesis develops a basic simulation model of network controlled repeater(NCR)based on the RIS system-level simulation platform,and compares the performance of RIS and NCR.Through simulation,it is found that NCR will amplify the noise and interference to a certain extent,while RIS will not amplify the noise and the probability of causing interference is small.In addition,RIS has the characteristics of low power consumption and easy deployment,which makes it more advantageous in future deployment.