4x2 MIMO vs 2×2 MIMO

[rosan]

Hi There,

Would anyone explain me the difference between these two please in terms of codewords, layers and antenna ports please?

Thanks

rosan

[rimeka]

4x2 MIMO has possibility
- 4 Tx diversity
- 2x2 SM and 2Tx diversity

[jbada]

Hi Fórum

4 X 2 MIMO in eNodeB is refering 4 antenas TX [Spatial multiplexing or divesity] (maybe 2 streams only due the current UE are 1x2) and 2 RX reception in diversity due the UE only send 1 stream
2 X 2 MIMO in eNodeB is 2 antenas TX [Spatial multiplexing or divesity] (2 streams) and 2RX reception in diversity due UE only send 1 stream.

[rosan]

So it is only 2 streams transmitted through 4 antennas i.e. One stream through two antennas.

rosan

[jbada]

Hi Rosan,

Yes 2 streams or 2 layers, because the majority of UE's in the market are class 3. The max layer in LTE is 4 layer.
Correct one stream through 2 antennas to transmit in diversity.
Be aware 4xx is a feature that the vendors are selling

[firstmaxim]

The no of layers (streams) employed on DL, will depend on the UE's MIMO feedback (CQI, PMI, and RI), which is indicative of channel condition, and the UE Capability. The higher ranks would be used only if the channel quality is excellent. So, MIMO exploits good channel conditions (some opportunistic scheduling done by eNode B), while at the cell edge, transmit diversity is employed instead. The same duplicate information, is sent on multiple streams. The combined signal improves the C/I significantly, and hence providing some coverage boost and robustness.