Patent ID: 8693567

Claim:
A precoding method in a multiple input multiple output (MIMO) system, the method comprising: in an evolved NodeB: receiving, by a processor, a non-constant modulus channel information matrix fed back by a user equipment; obtaining a constant modulus channel information matrix by removing amplitude information of each element in the non-constant modulus channel information matrix; obtaining a precoding matrix according to the constant modulus channel information matrix; and precoding data to be sent by using the precoding matrix, wherein the non-constant modulus channel information matrix is determined according to: c i = 1 ∑ j = 1 : N ⁢ ⁢  α i ⁢ ⁢ j  2 ⁡ [ α i ⁢ ⁢ 1 ⁢ ⅇ j ⁢ ⁢ θ i ⁢ ⁢ 1 ⁢ α i ⁢ ⁢ 2 ⁢ ⅇ j ⁢ ⁢ θ i ⁢ ⁢ 2 ⁢ ⁢ … ⁢ ⁢ α i ⁢ ⁢ N ⁢ ⅇ j ⁢ ⁢ θ i ⁢ ⁢ N ] T wherein c i is the non-constant modulus channel information matrix, α ij is a positive real number and one of amplitude information on a transmit antenna j and amplitude information on a jth transmit antenna of an ith code word, e jθ i2 is phase information of α ij , j indicates a label of the transmit antenna, T represents a transpose operation, and N is a number of transmit antennas.