Research On Hybrid Beamforming In 5G Optical And Wireless Fusion Fronthaul

One of the basic requirements of next-generation mobile communications is to improve spectrum efficiency.In order to achieve key performance indicators of 5G capacity,millimeter waves need to be used for communications.Millimeter waves have a wide frequency range(30?300Ghz)and can provide higher data transmission.However,as the frequency becomes higher,the path loss and penetration loss also increase.In order to combat the high transmission loss of millimeter wave,dense deployment of access points is required.Cloud Radio Access Network(C-RAN)provides an effective connection method for ultra-densely deployed millimeter wave access points.In 5G C-RAN Among them,the base station is divided into a central unit(CU),a distributed unit(DU)and an active antenna unit(AAU).The optical and wireless convergence fronthaul technology is one of the most efficient technologies for data transmission between DU and AAU.In the 5G optical and wireless fusion fronthaul system,in order to improve the user's receiving rate,beamforming technology based on array antennas can be used,and the hybrid digital/analog hybrid beamforming technology can simultaneously take into account system performance and hardware complexity.An effective technique.The specific work and contributions of this paper are as follows:(1)In order to better use hybrid beamforming technology in 5G optical and wireless fusion fronthaul,this paper designs an optical codebook,and proposes a single optical codebook-based single optical codebook applied to 5G optical and wireless fusion fronthaul systems.User hybrid beamforming system,which deploys optical codebooks in CU/DU to achieve centralized control and centralized calculation,making the structure of AAU relatively simple,and can reduce costs when deploying a large number of AAUs.On this basis,it is proposed A single-user hybrid beamforming algorithm based on optical codebook is proposed,and the algorithm is compared with the orthogonal matching pursuit algorithm through numerical simulation,and the performance is very close.This paper also expands the bill of lading user system into a multi-user system,and designs a multi-user hybrid beamforming algorithm based on an optical codebook.When the number of RF links is greater than the number of users,this algorithm is similar to the classic two-stage algorithm.In comparison,redundant RF links can be used to improve the average spectrum efficiency of users.(2)For the 5G optical and wireless fusion fronthaul system,the intelligent reflector is introduced into the proposed single-user/multi-user hybrid beamforming system based on optical codebook.This paper jointly optimizes the active beamforming based on optical codebook at AAU.In combination with passive beamforming at the smart reflector,a smart reflector-assisted single-user hybrid beamforming algorithm based on optical codebooks and two smart reflector-assisted multi-user hybrid beamforming algorithms based on optical codebooks are proposed.Numerical simulation of the algorithm is carried out.The research results show that the introduction of smart reflectors can further improve the user's received signal-to-noise ratio and increase the coverage of the system;the proposed hybrid beamforming algorithm based on optical codebooks is comparable to the fully digital beamforming algorithm Compared with the case of similar performance,the number of expensive radio links required is reduced,so the deployment cost can be reduced.