Patent ID: 8265698

Claim:
A method implemented in a base station of performing multi-rank, quantized beamforming, comprising: precoding data using a precoding matrix that is selected from a codebook comprising codebook entries V in the form V = [ v 1 , Φ ⁡ ( v 1 1 ) ⁢ HH ⁡ ( v 1 Φ ⁡ ( v 1 1 ) - e 1 M ) ⁡ [ 0 v 2 ] , Φ ⁡ ( v 1 1 ) ⁢ HH ⁡ ( v 1 Φ ⁡ ( v 1 1 ) - e 1 M ) ⁡ [ 0 Φ ⁡ ( v 1 2 ) ⁢ HH ⁡ ( v 2 Φ ⁡ ( v 1 2 ) - e 1 M - 1 ) ⁡ [ 0 v 3 ] ] ] , … where the base station has M=2 antennas, e 1 N =[1, 0, . . . , 0] T εC N (N=M, M−1, . . . ), C N being N-dimensional complex space, v a denotes a column vector, v b a denotes the b th element of the vector v a , Φ ⁡ ( v b a ) = v b a  v b a  , HH ⁡ ( w ) = { I - 2 ⁢ ww H  w  2 if ⁢ ⁢ w ≠ 0 I if ⁢ ⁢ w = 0 is the house-holder transformation of the vector w and v a is selected from a set V a where V 1 = 1 2 ⁢ { [ 1 , 1 ] T , [ 1 , - 1 ] T , [ 1 , j ] T , [ 1 , - j ] T } , where j=√{square root over (−1)}, and V 2 ={e 1 1 }; and transmitting the precoded data to a mobile terminal.