Research On Millimeter Wave Enhanced Coverage Based On LIS

With the rapid development of the Internet of Things and mobile Internet,the various wireless services and applications will be constantly explored to meet the more demand of spectral efficiency,power consumption and user access in the next generation communication system.Due to a large amount of advantages,such as tiny wavelength,enormous bandwidths and so on,mm Wave can be seen as a promising candidate.There is a brand development prospect in in a limited range wireless communication.Nevertheless,it occurs to much poor diffraction and bad penetration in the mm Wave propagation.The large intelligent surface(LIS)is proposed to improve the performance of channel propagation.To provide a high-quality auxiliary link,LIS has an effect of multipath that can offset some path loss.In addition,to improve the number of access users,it is valuable to research the non-orthogonal multiple access(NOMA).Different from the traditional orthogonal multiple access,the NOMA can share the resource of multiuser,including the same time,frequency,space,etc.The topic that the user coverage enhancement hybrid beamforming with the link of LIS under NOMA is researched.Firstly,the concept,including the characteristics of mm Wave communication,the MISO-NOMA system model and the mechanism of LIS,is introduced.And,it is a significant research how to design the multi-user beamforming algorithm and the weight of the LIS to maximize the weighted sum rate(WSR)of the system.Then,with LIS under the condition of the completely known channel state information(CSI).we mainly study the maximum WSR with optimization design of channel precoding and LIS phase matrix.The low complexity BCD algorithm based on forced zero precoding is adopted so that the optimization problem is decomposed into four subproblems.It is evident that a stationary solution can be obtained by iterative optimization.In this dissertation,LIS reflection matrix based on Riemann conjugate gradient algorithm and WMMSE precoding algorithm are used to maximize the sum rate of the system.Due to the high-quality auxiliary link and the performance gain brought by LIS reflection matrix,the joint optimization of LIS reflection matrix and precoding matrix will bring high benefits to the system.Finally,according to the method of Riemann manifold,the hybrid beamforming with the link of LIS is researched,on this basis,the Riemann Conjugate Gradient(RCG)algorithm was used to optimize the LIS reflection matrix..Some simulation results show that the proposed scheme has better performance than other schemes both in terms of transmitting antenna and the number of LIS elements.