Patent ID: 8111780

Claim:
A communication apparatus, comprising: a codebook storage unit configured to store at least one matrix W i , where i is a natural number; and a precoder configured to precode a data stream desired to be transmitted based on a precoding matrix comprising one of the stored at least one matrix W i , wherein each diagonal block, among a plurality of blocks included in each of the at least one matrix W i , comprises a nonzero matrix, the nonzero matrix excluding a zero matrix, and wherein each remaining block among the plurality of blocks, excluding the diagonal blocks, comprises the zero matrix, wherein the at least one matrix W i comprises: 1 2 ⁡ [ 1 0 1 0 0 1 0 - j ] ; 1 2 ⁡ [ 1 0 1 0 0 1 0 j ] ; 1 2 ⁡ [ 1 0 - j 0 0 1 0 1 ] ; 1 2 ⁡ [ 1 0 - j 0 0 1 0 - 1 ] ; 1 2 ⁡ [ 1 0 - 1 0 0 1 0 - j ] ; 1 2 ⁡ [ 1 0 - 1 0 0 1 0 j ] ; 1 2 ⁡ [ 1 0 j 0 0 1 0 1 ] ; and ⁢ ⁢ 1 2 ⁡ [ 1 0 j 0 0 1 0 - 1 ] .