摘要 |
Precoding a plurality of subcarriers in preparation for MIMO transmission is carried out by deriving preceding matrices from available information. When the number of data streams borne by the subcarriers equates to the number of transmit antennas employed in the MIMO transmission, the method comprises deriving, from respective acquired unitary precoder matrices for two of said subcarriers, interpolated precoder matrices for data streams intermediate the two subcarriers. The acquired and interpolated precoder matrices are then applied, as the case may be, at the respective subcarriers. The step of deriving the interpolated precoder matrices comprises determining an overall rotation matrix representing a transformation between the acquired precoder matrices, determining from the overall rotation matrix a further rotation matrix representing a step transformation for interpolation steps between said two subcarriers, and recursively applying said further rotation matrix to derive said interpolated precoder matrices. In the event that the number of data streams is less than the number of transmit antennas employed in said MIMO transmission, the rectangular precoder matrices should first be converted into square unitary matrices.
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