Research On Key Technology Of Wireless Cellular Network Based On Intelligent Reflecting Surface

Intelligent reflecting surface(IRS)is a two-dimensional metallic surface composed of intelligent meta-materials with uniformly arranged passive elements,which plays a crucial role in the development of wireless communication and can be used to transmit signals in the target direction by adjusting the reflection coefficient of the reflecting elements in real time.However,there are many points that need further research on how to effectively play the role of IRS in IRS-aided communication systems,firstly,how to adjust the reflection coefficient of the reflecting element more effectively,and secondly,how to make accurate channel estimation since the adjustment of the reflection coefficient in the reflecting element is directly related to the channel state information(CSI).The main research contents and innovations of this paper are summarized as follows:(1)The current status of wireless communication development and some key technologies of future 6G are investigated comprehensively,and the importance of IRS for wireless communication systems is introduced through an in-depth analysis of the advantages and limitations of key technologies of current and future 6G wireless communication systems.In addition,the current research progress of IRS is investigated and summarized according to the research content.Finally,the necessity of IRS-assisted inter-cell interference(ICI)mitigation and channel estimation for wireless communication systems is analyzed and demonstrated based on the research results.(2)The IRS-based ICI cancellation scheme is proposed to address the problem of ICI affecting the communication quality of cell edge users in cellular cell networks.Due to the non-convexity of the optimization problem constructed based on a multi-cell multiuser scenario,we propose the use of fractional programming(FP)to transform the original optimization problem into a more tractable form,and then use the block coordinate descent(BCD)algorithm to jointly optimize the base station(BS)and IRS beam.The simulation results show that the proposed scheme can effectively improve the system throughput and demonstrate that IRS deployment around the user can better improve the communication quality.(3)The problem of channel estimation in IRS-assisted wireless communication systems is investigated.Since the BS and IRS locations are fixed,it can be assumed that the CSI of the BS-IRS link is known,so only the CSI of the IRS-user link needs to be estimated.The spatial basis expansion model(SBEM)does not require the channel covariance matrix for channel estimation,so it has the advantage of low computational complexity compared with the conventional channel estimation algorithm,and the SBEM method can improve the utilization of the guide frequency resources by grouping users.The simulation results demonstrate that the SBEM method can effectively estimate the IRS-user channel with low signal-to-noise ratio(SNR)and can more effectively utilize the orthogonal guide frequency sequence.There are 19 figures,3 tables and 105 references in this paper.