Section 4 LTE at a glance!
Single user MIMO
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This is an example of downlink 2x2 single user MIMO with precoding.
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Two data streams are mixed (precoded) to best match the channel conditions.、
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The receiver reconstructs the original streams resulting in increased single-user data rates and corresponding increase in cell capacity.
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2x2 SU-MIMO is mandatory for the downlink and optional for the uplink
Multiple user MIMO
- Example of uplink 2x2 MU-MIMO.
- In multiple user MIMO the data streams come from different UE.
- There is no possibility to do precoding since the UE are not connected but the wider TX antenna spacing gives better de-correlation in the channel.
- Cell capacity increases but not the single user data rate.
- The key advantage of MU-MIMO over SU-MIMO is that the cell capacity increase can be had without the increased cost and battery drain of two UE transmitters.
- MU-MIMO is more complicated to schedule than SU-MIMO
