Patent ID: 8504098

Claim:
A transmitter used in a wireless communications system, the transmitter comprising: a precoding unit to precode data with 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 transmit 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 a transmission unit to transmit the precoded data to a receiver.