Spatial multiplexing have drawn a lot of attention for many years due to their great potential to achieve high throughput of MIMO systems implemented in wireless communication systems. It is well known that in a single user case the capacity scales linearly with the minimum number of transmit and receive antennas. Many linear precoding techniques require each antenna to transmit its own data. In this paper, we analyze the latest technology of MIMO with theoretic background. We compare the increasing features of capacity by using two precoding methods based on spatial multiplexed system. We apply two precodings to multiple antennas, considering MU-MIMO downlink. Finally, the simulation result demonstrates how the number of antennas has an effect on capacity.