Patent ID: 9178591
Filing Date: 2015-11-03
Classification: H04B,H04L

Abstract:
1. A method, comprising: in a mobile communication terminal, holding a definition of a sub-sampled codebook identifying precoding matrices to be used for providing precoding feedback by the terminal, wherein the precoding matrices in the sub-sampled codebook are selected from a master codebook that is made-up of a first sub-codebook and a second sub-codebook, wherein the first sub-codebook represents a first precoding component and the second sub-codebook represents a second precoding component that varies more rapidly than the first precoding component, and wherein the definition defines a first subset of the first sub-codebook and a second subset of the second sub-codebook; receiving in the terminal a Multiple-Input Multiple-Output (MIMO) signal via multiple receive antennas; and based on the received MIMO signal, selecting from the sub-sampled codebook a precoding matrix for precoding subsequent MIMO signals transmitted to the terminal, by combining a first matrix selected from the first sub-codebook and a second matrix selected from the second sub-codebook, and calculating the precoding feedback indicating the selected precoding matrix.