A first device of a wireless communications system, comprising: a receiving module, configured to receive a reference signal from a second device of the wireless communications system; a processing module, configured to: perform channel estimation based on the reference signal to obtain a channel matrix; decompose the channel matrix to obtain an unquantized precoding matrix; and generate channel information used to describe the unquantized precoding matrix, wherein the processing module is specifically configured to: use amplitude information and phase information of each element in the unquantized precoding matrix as the channel information used to describe the unquantized precoding matrix; and a sending module, configured to send the channel information used to describe the unquantized precoding matrix to the second device, wherein the sending module is specifically configured to: add each of the amplitude information and the phase information of each element in the unquantized precoding matrix to a ZC sequence, and send the ZC sequence to the second device; wherein the processing module is specifically configured to: perform singular value decomposition SVD on the channel matrix, to obtain, after the decomposition, a diagonal matrix and a matrix consisting of an eigenvector of the channel matrix; determine a rank of the channel matrix based on the diagonal matrix; and transform, based on the rank of the channel matrix, the matrix consisting of the eigenvector of the channel matrix to obtain the unquantized precoding matrix, wherein a quantity of columns of the unquantized precoding matrix is equal to the rank of the channel matrix. a receiving module, configured to receive a reference signal from a second device of the wireless communications system; a processing module, configured to: perform channel estimation based on the reference signal to obtain a channel matrix; decompose the channel matrix to obtain an unquantized precoding matrix; and generate channel information used to describe the unquantized precoding matrix, wherein the processing module is specifically configured to: use amplitude information and phase information of each element in the unquantized precoding matrix as the channel information used to describe the unquantized precoding matrix; and a sending module, configured to send the channel information used to describe the unquantized precoding matrix to the second device, wherein the sending module is specifically configured to: add each of the amplitude information and the phase information of each element in the unquantized precoding matrix to a ZC sequence, and send the ZC sequence to the second device; wherein the processing module is specifically configured to: perform singular value decomposition SVD on the channel matrix, to obtain, after the decomposition, a diagonal matrix and a matrix consisting of an eigenvector of the channel matrix; determine a rank of the channel matrix based on the diagonal matrix; and transform, based on the rank of the channel matrix, the matrix consisting of the eigenvector of the channel matrix to obtain the unquantized precoding matrix, wherein a quantity of columns of the unquantized precoding matrix is equal to the rank of the channel matrix. use amplitude information and phase information of each element in the unquantized precoding matrix as the channel information used to describe the unquantized precoding matrix; and a sending module, configured to send the channel information used to describe the unquantized precoding matrix to the second device, wherein the sending module is specifically configured to: add each of the amplitude information and the phase information of each element in the unquantized precoding matrix to a ZC sequence, and send the ZC sequence to the second device; wherein the processing module is specifically configured to: perform singular value decomposition SVD on the channel matrix, to obtain, after the decomposition, a diagonal matrix and a matrix consisting of an eigenvector of the channel matrix; determine a rank of the channel matrix based on the diagonal matrix; and transform, based on the rank of the channel matrix, the matrix consisting of the eigenvector of the channel matrix to obtain the unquantized precoding matrix, wherein a quantity of columns of the unquantized precoding matrix is equal to the rank of the channel matrix. perform singular value decomposition SVD on the channel matrix, to obtain, after the decomposition, a diagonal matrix and a matrix consisting of an eigenvector of the channel matrix; determine a rank of the channel matrix based on the diagonal matrix; and transform, based on the rank of the channel matrix, the matrix consisting of the eigenvector of the channel matrix to obtain the unquantized precoding matrix, wherein a quantity of columns of the unquantized precoding matrix is equal to the rank of the channel matrix.