关键词: MIMO，预编码，正交投影，料投影

Abstract: In current MU-MIMO systems orthogonal projection method is generally emploied in the user channel to maximize the performance of the worst channel by increasing the minimum channel gain. We introduced the research of linear precoding in multi user MIMO system and the mathematical preliminaries of oblique projcction,and then implemented oblique projection technique into I31)GMI)system, proposed a novel linear precoding based on oblique projection to reduce the gain loss caused by the orthogonal projection method and further increase the system capacity. System model of this precoding algorithm is in detail, and derive out the closed-form expression of system capacity by implementing water-filling power allocation algorithm into the model. Simulation shows that in low SNR the proposed scheme can obtain higher system capacity than the orthogonal projection schema.

Key words: MIMO, Precoding, Orthogonal projection, Oblique projection