Patent ID: 8208458

Claim:
A method for communications device operation, the method comprising: generating a channel estimate of a communications channel between the communications device and a controller serving the communications device; quantizing the channel estimate using a codebook, wherein the codebook is in accordance with a rank of communications between the communications device and the controller and comprises a plurality of first level codewords each having a plurality of subsidiary codewords, wherein a codeword is selected as a selected codeword in accordance with the channel estimate; and transmitting an index corresponding to the selected codeword; and wherein the controller comprises four transmit antennas, and wherein the codebook is expressible as: W=D×[W 1 ; . . . ;W 64 ], where D is the phase rotation diagonal matrix and given by D = [ ⅇ j ⁢ ⁢ θ 1 0 … 0 0 ⅇ j ⁢ ⁢ θ 2 ⋱ ⋮ ⋮ ⋱ ⋱ 0 0 … 0 ⅇ j ⁢ ⁢ θ 64 ] , where θ i ε[0,2π),iε[1, . . . , 64].