Abstract:In order to improve the performance of block diagonalization precoding algorithm,an improved algorithm was proposed for multiuser multiple-input multiple-output (MIMO) downlink systems,which employs QR decomposition based on Givens transformation.In the block diagonalization precoding algorithm,the first half of the precoding matrix is required to solve the problem of multi-user interference,and the latter one to reduce the interference between the antennas of each user.The core algorithm of the first half matrix is orthogonalization algorithm,which will directly affect the bit error rate (BER) performance of the block diagonalization precoding algorithm.Therefore,the original orthogonalization algorithm was replaced by QR decomposition algorithm based on Givens transformation.Using this algorithm to solve the first half of the precoding matrix,the orthogonal basis of the interference matrix's zero space can be obtained.By using the Givens transformation,the matrix with better orthogonality can be obtained,so as to further reduce the BER of the system.The simulation results showed that compared with the traditional block diagonalization algorithms,the complexity of the system was decreased and the BER performance can be improvedgreatly.Compared with the block diagonalization algorithms based on Gram-Schmidt orthogonalization,the BER performance can be improved by 3~5 dB,with a slight increase in the algorithm complexity.