Patent ID: 8711958

Claim:
A method for decoding a received signal Y corresponding to a data signal transmitted in a MIMO communication system through a channel represented by a channel matrix H, said data signal comprising a set of data symbols x transmitted in at least one layer, each layer carrying at least one data symbol belonging to a signal constellation, wherein said method comprises, for one of said at least one layer, called a current layer n: a detection step that determines the maximum likelihood for at least one data symbol of said data signal, wherein said detection step comprises: selecting one candidate value for the data symbol of the current layer n, and determining, with a processor, the Euclidian distance between the received signal Y and the data signal transmitted using said candidate value multiplied by said channel matrix H, weighted by the inverse of a noise covariance matrix C such as ∥Y−Σ i H i x i ∥ C −1 2 , expressed as: ∑ i ≠ n ⁢  H i  C - 1 2 ⁢  x i  2 - 2 ⁢ ⁢ ( H i H ⁢ C - 1 ⁢ Y - 0.5 ⁢ ∑ j ≠ i , n ⁢ H i H ⁢ C - 1 ⁢ H j ⁢ x j ) ⁢ x i * +  H n  C - 1 2 ⁢  x n  2 - 2 ⁢ ⁢ ( H n H ⁢ C - 1 ⁢ Y - ∑ j ≠ n ⁢ H n H ⁢ C - 1 ⁢ H j ⁢ x j ) ⁢ x n * = ∑ i ≠ n ⁢ α i R ⁡ ( ⁢ x i ) 2 - 2 ⁢ β i R ⁢ ⁢ x i + α n R ⁡ ( ⁢ x n ) 2 - 2 ⁢ β n R ⁢ ⁢ x n + ∑ i ≠ n ⁢ α i I ⁡ ( ⁢ x i ) 2 - 2 ⁢ β i I ⁢ ⁢ x i + α n I ⁡ ( ⁢ x n ) 2 - 2 ⁢ β n I ⁢ ⁢ x n wherein: H k is a vector representing the channel associated to a layer k, with kε{i, j, n}, i, j, nε[0, N−1], i, j, n being integers, possibly equal and N being the number of layers of said data signal; x k is the constellation symbol of the layer k; α k R =α k I =α k =∥H k ∥ 2 C −1 , β i≠n R = H i H C −1 Y− 0.5Σ j≠i,n H i H C −1 H j x j , β i≠n I = H i H C −1 Y− 0.5Σ j≠i,n H i H C −1 H j x j , β n R = H n H C −1 Y−Σ j≠n H n H C −1 H j x j , β n I = H n H C −1 Y−Σ j≠n H n H C −1 H j x j , wherein the terms depending on α k are computed by adding to each of them a predetermined constant depending on the size of the constellation of the layer k, called a constellation dependent constant.