基于发射相关的MIMO反馈增强与多用户调度方案

MIMO Multiuser Scheduling Schemes with Improved Limited Feedback Architectures Based on Transmit Correlation

针对多输入多输出(MIMO)多用户系统基于瞬时信道状态信息反馈的调度算法中反馈链路负载比较大的问题,提出了两种基于信道发射相关矩阵的反馈增强与多用户调度方案。方案一中,信道相关矩阵的对应最大奇异值的右奇异向量被反馈回发射端,发射机从这些向量表征的子信道中选择增益较大且空间互相关最小的一组,由于信道相关矩阵变化缓慢,因而大大减小了反馈负载;方案二进一步要求每个用户反馈瞬时信道矩阵的最大奇异值,只有该值大于某个预设门限的子信道才有可能被发射机选择,排除了较差的子信道。仿真表明,当发射天线的离开角角度扩展较小的时候,这两个方案以较小的性能损失大大减小反馈量。

Focusing on the high load of feedback link in scheduling scheme based on instantaneous channel information, two scheduling schemes that required limited feedback based on channel correlation matrices were proposed In the first scheme, each user sends back the right singular vector corresponding to the maximum singular value of its channel correlation matrix, from which the transmitter selects a set of vectors that are most spatially uncorrelated. Because correlation matrices change slowly, the feedback load can be decreased significantly. Further, in the second scheme, the feedback of the maximum singular value of instantaneous channel matrix is required for each user Only subchannels with gain larger than a certain threshold would be scheduled so that bad subchannels are excluded. Simulations demonstrate that feedback load decreases greatly with rather small performance degradation comparing with the algorithm based on instantaneous channel information when the angular spread in the transmit antennas is small.