;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.
