Research On Limited Feedback Technologyof Channel State Information In New Generation Wireless Communication

Limited feedback technology and mmWave technology are important technical means in NR.In mobile communication,as the number of base station antennas increases,the codebook increases,and the channel state changes rapidly in the mmWave channel,the NR technology imposes higher requirements on the limited feedback technique.This paper studies the related problems of limited feedback technology in mobile communication.The main research contents include:1.Codebook performance was studied.The codebooks studied in this paper mainly include RVQ codebook,codebook based on Lloyd algorithm,Grassmannian codebook and DFT codebook.The RVQ codebook is randomly generated,and the best codeword is generated in an iterative manner.The codebook based on the Lloyd algorithm is iteratively generated according to the nearest neighbor condition and the centroid condition.The Grassmannian codebook is generated by maximizing the minimum distance between each codewords,which is the theoretical optimal codebook.The DFT codebook is directly generated by the discrete Fourier transform,which is a simple codebook.2.The type ? codebook search methods in the NR technical standard are studied.The block-based and path-based codeword search algorithms are studied in this paper,and the performance of the two algorithms is compared.According to the characteristics of the type ? codebook,this paper proposes a hierarchical codebook search algorithm based on the binary search method.The selection of codewords is limited to the optimal partition.It can be seen from the system simulation that the hierarchical codebook search algorithm based on the binary search method can obtain better gain than other codebook search algorithms.3.Multi-user selection algorithm based on BD algorithm in MU-MIMO system is studied.In this paper,a new CQI feedback technique based on BD algorithm is studied.By calculating the expected value of the precoding matrix,the user's achievable rate is estimated,and the upper and lower bounds of each user's achievable rate are obtained.In the user selection phase,an improved user selection method S-SUS is proposed.The algorithm reduces the complexity of the user selection algorithm without reducing the performance of the system.Both the derivation result and the simulation result show that the multi-user diversity gain and corresponding throughput that can be achieved by the CQI feedback method used in this paper are higher than the existing CQI feedback mode.4.User beam selection based on limited feedback and hybrid precoding is studied.The paper first studies the impact of channel-based codebooks on system performance.In the beam selection phase,the previous user selection method based on hybrid precoding is improved,and the influence of channel estimation error on system performance is analyzed.It can be seen from the simulation that the performance of the improved user beam selection algorithm in this paper is close to the performance of all-digital ZF precoding.When the number of antennas of the UE and the BS increases,the channel estimation error has little effect on system performance.