Method for Removing Signal Interference Based on Multiple Input Multiple Output

1. A method for removing signal interference in a MIMO-based interference removing apparatus, the method comprising: transmitting a reference signal to at least one receiver; if channel information is estimated by the receiver, receiving the estimated channel information from the receiver as a feedback signal; producing a transmission pre-coding matrix, a beam forming matrix, and a weighted matrix using the received channel information; and transmitting information containing the transmission pre-coding matrix, the beam forming matrix, and the weighted matrix by including them in a pilot signal to the receiver, wherein the MIMO-based interference removing apparatus comprises at least one transmitter.

2. The method of claim 1 , wherein upon receiving the pilot signal, the receiver produces a received beam forming matrix and transmits it to the transmitter.

3. The method of claim 1 , wherein the transmitter comprises at least one wireless AP or at least one relay and the receiver comprises at least one wireless terminal.

4. The method of claim 1 , wherein said producing transmission pre-coding matrix, beam forming matrix, and weighted matrix using the received channel information comprises: initializing the transmission pre-coding matrix with respect to the transmitter and the receiver; calculating the beam forming matrix with respect to the transmitter and the receiver; calculating the weighted matrix with respect to the transmitter and the receiver; calculating the transmission pre-coding matrix in case of constraining a transmission power of the transmitter, or the transmission pre-coding matrix in case of constraining a transmission power of the receiver; and repeatedly performing the calculations until the weighted sum mean square error (MSE) of the weighted matrix converges on a predetermined threshold value.

7. The method of claim 5 , wherein the covariance matrix is calculated by the following equation: Φ [ k , i ] = ( σ n 2 + σ e 2 ⁢ ∑ ( 1 , j ) ⁢ tr ⁢ { V [ 1 , j ] ⁢ V [ 1 , j ] ⁢ H } ) ⁢ I + ∑ ( 1 , j ) ⁢ H j [ k , i ] ⁢ V [ 1 , j ] ⁢ V [ 1 , j ] ⁢ H ⁢ H j [ k , i ] ⁢ H where σ e 2 denotes a variance value of noise influenced on the receiver, and where σ 2 n denotes a variance value of baseline noise.

9. The method of claim 8 , wherein the transmission pre-coding matrix is calculated by the following equation in cases where a transmission power of the transmitter is constrained: V [ k , i ] = ⁢ ( ∑ ( i , j ) ⁢ μ [ 1 , j ] ⁢ H ~ i [ 1 , j ] ⁢ H ⁢ U [ 1 , j ] ⁢ W [ 1 , j ] ⁢ U [ 1 , j ] ⁢ H ⁢ H ~ i [ 1 , j ] + σ e 2 ⁢ ∑ ( i , j ) ⁢ μ [ 1 , j ] ⁢ tr ⁢ { W [ 1 , j ] ⁢ U [ 1 , j ] ⁢ H ⁢ U [ 1 , j ] } ⁢ I + λ i ⁢ I ) - 1 × μ [ k , i ] ⁢ H ~ i [ k , i ] ⁢ H ⁢ U [ k , i ] ⁢ W [ k , i ] where μ [k,i] denotes the priority of the receiver, λ i denotes a Lagrange Multiplier of the transmitter, which selects a value satisfying ∑ k = 1 K i ⁢ tr ⁢ { V [ k , i ] ⁢ V [ k , i ] ⁢ H } ≤ P i , and P i denotes an upper limit of the transmission power of the transmitter.

10. The method of claim 8 , wherein the transmission pre-coding matrix is calculated by the following equation in case where a transmission power of the receiver is constrained: V [ k , i ] = ( ∑ ( i , j ) ⁢ μ [ 1 , j ] ⁢ H ~ i [ 1 , j ] ⁢ H ⁢ U [ 1 , j ] ⁢ W [ 1 , j ] ⁢ U [ 1 , j ] ⁢ H ⁢ H ~ i [ 1 , j ] + K i P i ⁢ σ e 2 ⁢ tr ⁢ { μ [ k , i ] ⁢ W [ k , i ] ⁢ U [ k , i ] ⁢ H ⁢ U [ k , i ] } ⁢ I + σ e 2 ⁢ ∑ ( 1 , j ) ⁢ tr ⁢ { ⁣ μ [ 1 , j ] ⁢ W [ 1 , j ] ⁢ U [ 1 , j ] ⁢ H ⁢ U [ 1 , j ] } ⁢ I ) × μ [ k , i ] ⁢ β ⁢ H ~ i [ k , i ] ⁢ H ⁢ U [ k , i ] ⁢ W [ k , i ] where β denotes a power normalization factor and K i denotes the number of the receivers related to the transmitter.