Codebook Design And Key Algorithm Research Based On Limited Feedback In LTE-A Downlink System

With the rising of the fourth generation of mobile communication technology, academic research on the LTE-Advanced is also growing. In recent years, MIMO enhancements technology based on the limited feedback is concerned.3GPP protocol 36.913 points out that LTE-A system should target a downlink peak data rate of 1 Gbps, so it requires the number of antenna must be extended to eight in downlink transmission system of LTE-A. At present, the codebook of 3GPP LTE Release 8 standard codebook only supports four antennas, therefore, the design and research for a codebook based on limited feedback supporting eight antennas and its key algorithm is necessary in LTE-A downlink system. This thesis proposes a codebook method designed for eight antennas in dowenlink system of LTE-A. The proposed method uses the rotation of the DFT-based codebook, and reuses the LTE Release 8 codebook, not only to maintain backward compatibility, but also inherit the good characteristics of LTE Release 8 codebook. Theoretical analysis and computer simulation confirm the validity of the method.Firstly this thesis describes the technical background about the codebook, and describes the application about codebook of limited feedback in wireless communication system. The application contains quantitative covariance, beamforming, spatial multiplexing with linear precoding. Secondly, based on the LTE Release 8 of the physical layer protocols, part of PDSCH sending module of the link level simulation platform is built. Then including codebook, precoding model is described. According LTE codebook and Samsung codebook, the recognized design principles of codebook are described. Finally, we introduce our idea of the proposed codebook:with combining the advantages of 8x8 DFT codebook in non-correlated channel, based on LTE Release 8 codebook, we design of the corresponding rotation block diagonalization matrix for dual-polarized channel to generate the LTE-A codebook. This has the advantages that it can not only maintain the backward compatibility of LTE-A, but also inherit many good features of the LTE codebook. We analysis the feedback overhead and the complexity of representative LTE Release 8 codebook and Samsung codebook in theoretical, and simulate them in the correlated channel, non-correlated channel and dual-polarized channel respectively. The simulation results show that the performance of proposed codebook algorithm are excellent, it can effectively reduce the block error rate, and also improve the system throughput, so that it is a suitable design and efficient codebook for LTE-A system.