Channel covariance feedback for enhanced fd-mimo

Abstract

Channel covariance feedback is disclosed for enhanced full-dimension multiple input, multiple output (eFD-MIMO) systems. Channel state information (CSI) reference signal (CSI-RS) feedback operations are implemented using spatial covariance feedback of a covariance estimate. After obtaining a set of orthogonal basis vectors, a user equipment (UE) measures the CSI-RS from a base station and determines the spatial covariance matrix from the signal. The UE may then compress the spatial covariance matrix into a lower-dimension covariance estimate matrix using the orthogonal basis vectors. The lower-dimension matrix along with element-wise quantization allows for feedback of spatial covariance for eFD-MIMO systems without excessive feedback overhead.

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