Why UL MIMO is not used widely? Why UL MIMO is only 4 * 4?

Question

For Downlink - 2*2 and 4*2 MIMO configurations, Which one gives better throughput and why ?.
Both have 2 receiving antennas.

Answer 1

Hi,

UL MIMO is not much useful, because UL data will be maximum signaling, but still they allowed to use 4 * 4 MIMO. If you increase MIMO then UE capability has to be increased, you cannot have more antenna at UE side because it leads some other problems like radiations , limitation of UE capability etc.