Patent ID: 8923427

Claim:
A method, comprising: in a mobile communication terminal, holding a definition of a sub-sampled codebook identifying precoding matrices, which are selected from a master codebook that is made-up of a wideband codebook and a frequency-selective codebook, wherein the definition defines a first subset of the wideband codebook and further defines a second subset of the frequency-selective codebook, wherein the second subset of the frequency-selective codebook is represented using no more than two bits; receiving in the terminal a Multiple-Input Multiple-Output (MIMO) signal; based on the received MIMO signal, selecting from the first subset a single precoding matrix, and selecting from the second subset multiple precoding matrices corresponding to multiple respective spectral sub-bands, for precoding subsequent MIMO signals transmitted to the terminal, and calculating precoding feedback indicating the single precoding matrix selected from the first subset and the multiple precoding matrices selected from the second subset; and transmitting the precoding feedback from the terminal.