With MU-MIMO, a base station can send multiple data streams, one for each User Equipment (UE), via the same time-frequency resources. MU-MIMO enables an increase in the total cell throughput/cell capacity. The base station will have multiple antenna ports, as many as there are UEs, which will be receiving data simultaneously. One antenna port is needed in each UE.
Essentially, more antennas will be deployed to achieve large gain from receive diversity and MIMO.
Figure 2: MU-MIMO sending multiple data streams, one for each UE, via the same time-frequency resources (Source: Qualcomm)