4G vs 3G

MIMO 


 -------> Multiple Antennas in the Receiver side and in the transmitter side.
This is one main reason for spectral efficiency. 
Offcourse everyone is puzzled on where there is main change when compared to 3G.
Is it on the radio? or in the n/w?
offcourse there are changes in radio which plays a significant role for more bw.
Not sure how far this MIMO antennas are going to help us.
Still not convinced with how far this is going to save the battery life.
There is going to be multiple transmitter antennas both in the transmitter and receiver..
MU-MIMO allows to increase the overall capacity
[                    ||||  ++++++                 
[  UE             ||||  ++++++
[                    ||||  ++++++



Spatial multiplexing allows to transmit different streams of data
simultaneously on the same resource block(s) by exploiting the spatial
dimension of the radio channel. These data streams can belong to one
single user (single user MIMO / SU-MIMO) or to different users (multi user
MIMO / MU-MIMO)



Multiple user terminals may transmit simultaneously on the same
resource block. This is also referred to as spatial division multiple access
(SDMA). The scheme requires only one transmit antenna at UE side which
is a big advantage.