中文摘要：

对多用户多输入多输出系统（multiple input multiple output,MIMO）传输模式切换进行了研究,在迫零（zero forcing,ZF）和最大传输比（maximal ratio transmit,MRT）两种预编码方式以及不同传输数据流数所定义的几种传输模式中,选取吞吐率最大的最优传输模式进行数据发送.首先,通过引入偏离角的概念,建立了发射端信道状态信息（channel state information at the transmitter,CSIT）误差模型;在此基础上,分析了CSIT误差对于ZF和MRT传输性能的影响,并给出了在CSIT误差与信噪比组成的二维空间中最优传输模式区域划分;最后,提出一种低复杂度的快捷传输模式切换算法.理论分析和仿真结果表明,在不同程度的CSIT误差条件下,该算法仍可保证可达吞吐率与信噪比间近似线性增长.

英文摘要：

Transmission mode switching in multiuser multiple input multiple output（MIMO） systems was investigated, where the transmission modes are defined by precoding schemes such as zero forcing（ZF） and maximal ratio transmit（MRT）, as well as the number of users（or data streams） that are served or transmitted. The optimal transmission mode is selected to maximize the system throughput. By introducing the deviation angle, a new channel state information at the transmitter（CSIT） error model was established. Based on which, the impacts of CSIT error on the system performance were respectively analyzed for ZF and MRT, and an optimal transmission mode region division was provided in the two-dimension space characterized by the CSIT error and SNR. After that, a simple but effective transmission mode switching algorithm was proposed. Theoretical analysis and simulation results revealed that with the proposed mode-switching algorithm, the system throughput can maintain linear increasing with the SNR at various CSIT error levels.