在現在通訊系統發展中，多輸入多輸出及正交分頻多工是很重要的技術與趨勢，加上5G時代的來臨，毫米波系統的使用及設計也逐漸受到重視，因此，本篇論文將多輸入多輸出技術及正交分頻多工技術結合至毫米波系統，並設定為下行通道多使用者的環境來作探討。
本篇論文之研究方法依據每個使用者在每個子通道做的奇異值分解之結果，在眾多使用者中優先挑選出通道條件較佳之使用者作訊息傳輸，即為子載波之配置，再經由不同方法分配每個使用者在每個子通道中所能傳送的資料流數量。論文提出針對子載波配置及資料流配置分別提出兩個方法:子載波配置的第一個方法為依據通道條件將子載波分配給通道較好的使用者，第二個方法則是加上使用者所能獲得之最多子載波之限制；資料流配置的第一個方法與前述方法相同，均根據通道條件做分配，第二個方法以第一個方法作為基礎，再經過論文所提出之疊代法以增加其頻譜效率。
論文最後提供了各個方法之配對比較結果圖，由實驗結果可得知，在不選滿使用者的情況下，做子載波配置且加上資料流配置的頻譜效率表現會好過於選滿使用者後做子載波配置且一個使用者僅使用一個資料流的表現；另外，模擬圖呈現使用本論文所提出之疊代法來調整原資料流配置的結果，可增加其總頻譜效率。

In the recent development of communication system, MIMO and OFDM are very important technology and also the trend in future. For the age of 5G communication is coming, the design of millimeter wave systems gradually received the attention. Therefore, in this thesis, we combine the MIMO and OFDM technology to mmWave system and assume the multiuser downlink environment.
The research method of this paper to allocate subcarriers and select users is according to the results of singular value decomposition (SVD) of the channels for each users at each subcarrier. At each subcarrier, the user who has the better channel condition has the right to transmit the signals. Then we allocate the data streams for users by using different schemes. For subcarrier allocation and data stream allocation, this thesis provides two schemes, respectively. The first scheme of subcarrier allocation is that select the users who have the higher singular values at each subcarrier and the second scheme is also based on the channel SVD but add the constraint of number of allocated subcarriers for each user. For the data stream allocation schemes, we assign more data streams to users who have the better channel condition (scheme1) then the iterative scheme (scheme2) is to reallocate the data streams for different users and calculate the data rate after reallocation. If the reallocated pairs can improve the performance, we save the reallocation results.
As the experimental results, the thesis proposed that the spectral efficiency of the scheme that each user transmits different number of data streams is higher than the scheme that each user transmits one data stream. Furthermore, the simulation result also presents that the proposed iterative data stream allocation scheme can improve the total spectral efficiency.

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