Patent ID: 8351986

Claim:
A method implemented in a transmitter used in a wireless communications system, comprising: precoding data using a precoding matrix selected from a codebook comprising matrices that are expressed as 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 transmitter has M 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 vector v a , Φ ⁡ ( v b a ) = v b a  v b a  , and ⁢ ⁢ HH ⁡ ( w ) = { I - 2 ⁢ ww H  w  2 if w ≠ 0 I if w = 0 is the house-holder transformation of vector w; and transmitting the precoded data to a receiver.