多天线有限反馈系统下基于Grassmannian流形的信道预测

Channel Prediction Based on Grassmannian Manifold for Limited Feedback Multiple Antenna Systems

针对时变信道下多天线有限反馈预编码系统存在反馈延迟的问题,在充分利用信道的时域相关性的基础上,提出将多天线时域相关信道的方向向量建模于Grassmannian流形上,利用Grassmannian流形的测地线对时变信道进行跟踪预测,以补偿反馈延迟对于系统性能的影响.同时,从Grassmannian流形的几何特性入手,针对Grassmannian流形的切空间提出了一种自适应的高分辨率动态聚焦码本.计算机仿真表明,基于Grassmannian流形的信道预测预编码的系统性能明显优于无记忆量化预编码,而且采用高分辨率动态聚焦码本对时变信道的跟踪性能也优于采用固定码本的信道预测.

Aimed at the feedback delay problem in the multiple-antenna limited feedback precoding systems,and based on the full use of the time correlations of time-varying channel,the linear vector spaces spanned by the channel direction vector was modeled as points on a Grassmannian manifold,and the adjacent channel directions were assumed to move along the geodesic on a Grassmannian manifold,in order to compensate the effect of feedback delay on the performance of the system.Meanwhile,by exploiting the differential geometric properties of the Grassmannian manifold,the dynamic focused codebook with high resolution on the tangent space of Grassmannian manifold was proposed,which tracked the correlated channel and updated itself accordingly.The computer simulation results show that the system performance of the proposed Grassmannian predictive precoding is obviously superior to that of memoryless quantitation precoding which has a shortcoming of feedback delay.Moreover,compared with the channel prediction of fixed codebook,the proposed dynamic focused codebook with high resolution is equipped with the higher quality of keeping tracking with the time-varying channel.