基于多径的双极化信道信息反馈方法

CSI Feedback Based on Multi-Paths Information in Dual-Polarized MIMO System

天线部署空间限制和信道信息精度是影响大规模天线性能的重要因素,双极化天线能够有效地减少天线尺寸,在有限的空间内部署更多的天线,成为了大规模天线部署时的主流选择.但是由于信道的维度较大,目前,反馈技术面临码本中码字数目巨大、设计困难的问题,并且同时导致反馈开销大以及码字选择计算复杂度高.本文提出了一种新的基于多径的双极化信道反馈方法,这种方法仅仅需要少量的长周期宽带反馈的多径方向和幅度信息,结合一些短周期子带反馈的相位合并信息即可获得更加精确的预编码.结果表明这种方法能够有效地提高量化反馈效率并降低终端侧复杂度.

The space limitation of antenna disposition and CSI precision are the important factors that influence the performance of massive MIMO. Dual-polarized antenna can be widely adopted to accommodate a large number of antenna elements in limited space. However, CSI feedback schemes in LTE are not efficient for FDD based massive MIMO as feedback overhead increases almost linearly with the increase of antenna number. Moreover, the codebook will also be huge and difficult to design if reusing the LTE methodology. In this paper, a novel CSI feedback mechanism was proposed for dual-polarized antenna system to achieve better performance with low feedback overhead. The MIMO channel was decomposed into long term components （multi- path directions and amplitudes） and short term component （multi-path phases）. The relationship between the two components and the optimal pre-code was also deduced in closed form. System level simulation results show that it can improve the performance considerably, improving feedback efficiency quantitatively and reducing the complexity of terminal.