在本篇論文中,我們主要專注在多輸入多輸出的非正交多重接取系統環境下,進行效能評估,使用的強制歸零預編碼Zero-Forcing (ZF)和最小均方誤差預編碼Minimum Mean Square Error (MMSE) 。因此,本文希望去探討不同預編碼在完美通道和具通道估測錯誤情況下,進行效能評估。利用預編碼可使用來降低干擾的程度,經過預編碼可以提升系統吞吐量 (capacity)。在模擬結果中進行比較並分析,提出不同形況下預編碼的選擇和使用。;In this thesis, we studied the performance of zero-forcing (ZF) and minimum mean square error (MMSE) precoding of Multiple Input Multiple Output (MIMO) in Non-orthogonal multiple access (NOMA) systems. The effect of channel estimation is considered. Therefore, we evaluate the performance with different precoding methods with perfect and imperfect channel estimation. While using precoding to suppress the interference, the sum capacity is improved. Finally, we suggest one precoding method to offer better sum capacity in choosing one of different precoding methods by comparing the performance of simulation results.