Abstract: Considering the problem of performance loss due to limited feedback in multiuser MIMO-OFDM downlink systems, an novel limited feedback precoding for multiuser MIMO systems based on double codebook is proposed. Only a part channels of subcarrier should be estimated, the maximum SINR criteria is used for selecting optimal codeword from the Grassmannian codebook and perturbation codeword at the receiving, exploiting the correlation between sub-carrier channels of OFDM（Orthogonal Frequency Dvision Multiplexing）, to feedback the Grassmannian precoding codeword index and perturbation codeword index to the transmitter and reconstructing the other precoding matrix, then the perturbation codeword is used at the transmitter to get optimal capacity, and compensating for the capacity performance loss due to the limited feedback. Simulation results show that the proposed method to ensure BER performance and the cost of the feedback link, the system throughput are improved effectively.

Key words: multiuser MIMO, Orthogonal Frequency Dvision Multiplexing（OFDM）, precoding, limited feedback, double codebook

摘要： 针对多用户MIMO-OFDM下行链路由有限反馈导致的性能缺失，提出了一种基于双码本的有限反馈预编码方案。该方案在接收端依据部分子载波信道信息并采用期望用户最大信干比准则，从预置码本中选取主码字及扰动码字反馈给发送端，在发送端根据子载波簇的相关性重构各子载波预编码矩阵，然后利用矩阵线性变换特性对主码字进行线性变换扰动以达到容量最优，从而补偿由于有限反馈导致的性能缺失。仿真结果表明，所提出的方法在保证反馈链路开销与系统误码性能的情况下，有效地改善了系统吞吐量。

关键词: 多用户MIMO, 正交频分复用, 预编码, 有限反馈, 双码本