MIMO Single User for LTE

MIMO Single User for LTE the pmi precoding loop spatial multiplexing mode rank indicator Each user is served by only one BS and it occupies the resource exclusively.

SU-MIMO = Single User MIMO
  • It is the most common form of MIMO.
  • Each user is served by only one BS and it occupies the resource exclusively, including
    time, frequency.
  • It can be applied in the uplink or downlink. But it is generally applied only in DL. The UE can easily have 2 antennas in reception but only 1 antenna can transmit

The Single User MIMO is used in DL and means that the 2 TB send by the 2 antennas using the same radio resources are for the same UE.
In UL, it is not possible to use this MIMO.

There are two operation modes in SU-MIMO spatial multiplexing: 
The closed-loop spatial multiplexing mode
  • The UE reports the CQI, the RI (Rank Indicator) and the PMI (Precoding Matrix indicator)
The open-loop spatial multiplexing mode
  • The reports only the CQI and the RI.
  • The RI (Rank Indicator) indicates the number of spatial layers (data streams) that can be supported by the current channel experienced at the UE.
  • The PMI (Precoding Matrix Indicator) is the UE feedback.

The required UE feedback for the MIMO are: 
  • RI, Rank Indicator. By this one the UE can indicate if it is able to separate 2 TB. If Yes the eNodeB can use the MIMO. If not it uses the TxDiv
  • PMI, Precoding Matrix indicator. It is used only for the Closed Loop MIMO. The UE indicates the eNodeB how to map the data on the 2 antennas to optimize the reception.

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