Channel orthogonalization precoding algorithms for multiuser MIMO downlink systems

In this paper, two precoding algorithms based on channel orthogonalization have been proposed for multi-user MIMO downlink systems. Unlike other conventional methods, the first scheme obtains the orthonormal basis to achieve the precoding matrix by means of using Schmidt Orthogonalization method. In this way, the co-channel interference can be eliminated to some degree. The second algorithm increases every user´s receive SINR (Signal to Interference plus Noise Ratio) by taking noise into account to balance the multi-user interference and the noise for every user. Simulation results show that the performance of our proposed schemes is very close to the conventional iterative scheme but significantly reduce the complexity with one data stream per user. For systems with multiple data streams per user, the second algorithm achieves better BER performance compared with several other algorithms.