Patent ID: 8477859

Claim:
A method for communications device operations, the method comprising: estimating, by the communications device, a channel between a controller and a mobile device; generating channel state information from the channel estimate; quantizing the channel state information by selecting a codeword from a rank n codebook in accordance with a codeword selection mechanism, where n is a non-negative integer value; transmitting an index corresponding to the selected codeword; and receiving a transmission from the controller, wherein the transmission is precoded in accordance with the index, wherein the rank n codebook comprises 2 K codewords with each codeword comprising n columns of a transformed base matrix of dimension N t ×N t , where K is a positive integer number representing a number of bits in the rank n codebook, and N t is a number of transmit antennas at the controller, and wherein an i-th codeword of the rank n codebook is expressible as C i =diag(u i )×DFT N t , where DFT N t is the base matrix, u i (n)=e jπ sin(k sin(θ i ))n , iε[0, . . . , 2 K −1], nε[0, . . . , N t −1], k is a constant, θ i ε[0,2π], and diag( ) is a function that returns diagonal elements of u i .