Patent ID: 8903007

Claim:
A method for determining a precoding matrix, comprising: determining, by a communication device, a rank constraint of a j th transmitting end; and calculating, by the communication device, iteratively an optimal precoding matrix of the j th transmitting end according to a channel matrix from the j th transmitting end to a j th receiving end, an autocorrelation matrix of interference and noise of the j th receiving end, and the rank constraint of the j th transmitting end, wherein the optimal precoding matrix maximizes channel capacity of a link from the j th transmitting end to the j th receiving end under a circumstance that precoding matrices of other transmitting ends do not change, j=1, 2, . . . , K, and K is a total number of the transmitting ends or receiving ends in a Multiple-Input Multiple-Output (MIMO) system; wherein the calculating iteratively the optimal precoding matrix of the j th transmitting end according to the channel matrix from the j th transmitting end to the j th receiving end, the autocorrelation matrix of interference and noise of the j th receiving end and the rank constraint of the j th transmitting end comprises: calculating iteratively a preset optimization problem; and obtaining a corresponding optimal solution when the preset optimization problem converges to a Nash equilibrium point during iterative calculation, wherein the optimal solution is the optimal precoding matrix of the j th transmitting end, wherein the preset optimization problem is max Q j ⁢ log ⁢ ⁢ det ⁡ ( I + H jj H ⁢ R j - 1 ⁢ H jj ⁢ Q j ) ⁢ subject ⁢ ⁢ to ⁢ Q j ≥ 0 ⁢ Rank ⁡ ( Q j ) ≤ r j ⁢ Trace ⁡ ( Q j ) ≤ P j , wherein log det(I+H jj H R j −1 H jj Q j ) denotes channel capacity of a link between the j th transmitting end and the j th receiving end, I denotes a unit matrix, H jj denotes a channel matrix from the j th transmitting end to the j th receiving end, R j denotes an autocorrelation matrix of interference and noise of the j th receiving end after the precoding matrix is iteratively updated last time, Q j =F j F j H , j=1, 2, . . . , K, K is the total number of the transmitting ends, Q j is an autocorrelation matrix of a transmitting signal of the j th transmitting end, F j is a precoding matrix of the j th transmitting end, r j is a rank constraint of the j th transmitting end, Rank(Q j ) denotes a rank of Q j , P j is a transmitting power constraint of the j th transmitting end, and Trace (Q j ) denotes a trace of Q j .