Patent ID: 8208576

Claim:
A method for transmitting signals at a transmitter of a Multi-Input Multi-Output (MIMO) system using a plurality of antennas, the method comprising: performing a precoding on one or more streams of signals at a precoder to map the one or more streams to the plurality of antennas using a precoding matrix with a subset index (i) selected from a subset of a codebook, wherein the subset index (i) cyclically increases every (v) contiguous resource indices within a range from 0 to (N restrict )−1, wherein (v) is a predetermined integer value, wherein the codebook includes (N) precoding matrices of {P 0 , P 1 , P 2 , . . . P (N)-1 }, each matrix having a codebook index (j), (j)=0, 1, . . . , (N)−1, wherein the subset of the codebook includes (N restrict ) precoding matrices having matrix elements corresponding to one of ‘1’, ‘−1’, ‘j’ and ‘−j’ and represented as: {P a , P b , P c , . . . P d }, wherein a, b, c, . . . , dε{0, 1, 2, . . . , (N)−1}, the number of a, b, c, . . . , d equals to the (N restrict ), and a<b<c< . . . <d, wherein the subset index (i) of each (N restrict ) precoding matrix, selected from the (N) precoding matrices, is defined as 0, 1, . . . , (N restrict )−1 to correspond to each codebook index of the selected precoding matrices, and wherein each of the subset indices of 0, 1, . . . , (N restrict )−1 corresponds in the order of a, b, c, . . . , d; and transmitting the precoded signals to a receiver.