Precoding method for multi-user multiple input multiple output (MIMO) system

The invention discloses a precoding method for a multi-user multiple input multiple output (MIMO) system, which comprises the following steps: by the feedback of each user or the specific channel reciprocity of a time division duplexing system, acquiring channel information Hi of each user of the multi-user MIMO system and noise power i = 1, 2,...K, wherein K is the number of users of the multi-user MIMO system; according to the channel information Hi of each user, acquiring a compensation channel of each user and carrying out channel expansion, acquiring a matrix and carrying out LQ decomposition on the matrix, and acquiring a lower triangular matrix Li and a unitary matrix Qi; carrying out conjugate transpose on a submatrix of Qi and then multiplying by Hi to obtain an equivalent channel of each user; carrying out singular value decomposition (SVD) on the equivalent channel to obtain a precoding matrix Wi of each user; and precoding data and pilot frequency to be transmitted to eachuser by Wi, and transmitting the precoded data and pilot frequency to each user. Under the condition that a user terminal has multiple antennae, by using the method of the invention, the effects of two factors of interference and noise between multiple users on the system are eliminated, the performance of the multi-user MIMO system is improved, and the complexity of a transmitting terminal is reduced.