Patent ID: 8761297

Claim:
A method, comprising: holding in a receiver a definition of a codebook comprising precoding matrices and a definition of multiple sub-codebooks comprising different respective subsets of the precoding matrices in the codebook, wherein the sub-codebooks are arranged in multiple levels that differ from one another in precoding resolution and precoding range; selecting in coordination with a transmitter a sub-codebook for use in a given time interval or frequency range; receiving a Multiple-Input Multiple-Output (MIMO) signal that is transmitted from the transmitter; and based on the received MIMO signal, generating in the receiver feedback that is indicative of one or more preferred precoding matrices, which are chosen from the selected sub-codebook and which are to be used in precoding subsequent MIMO signals in respective partitions of the given time interval or frequency range, and transmitting the feedback from the receiver to the transmitter.