The impact of the MIMO interference on the number of streams is basically visible in case of distributed MIMO systems.
In this case the MIMO antenna elements are located on different positions (e.g. inside other rooms) and thus experience different channel conditions, i.e. the power received from the different Tx antenna elements is no longer the same at a certain location. Then due to the assumed MIMO interference model (with e.g. 20 dB relative contribution of interference) it happens that some streams can be no longer received (due to the reduced SNIR) and thus the number of streams is reduced.
In case of co-located MIMO systems the channel conditions for the different Tx antenna elements are almost the same. Therefore you don’t experience a degradation of the number of streams due to the assumed MIMO interference, as in this case all the streams will be affected in the same way. Thus you have either all the streams transmitted or none at all.
The impact of the MIMO interference on the number of streams is basically visible in case of distributed MIMO systems.
In this case the MIMO antenna elements are located on different positions (e.g. inside other rooms) and thus experience different channel conditions, i.e. the power received from the different Tx antenna elements is no longer the same at a certain location. Then due to the assumed MIMO interference model (with e.g. 20 dB relative contribution of interference) it happens that some streams can be no longer received (due to the reduced SNIR) and thus the number of streams is reduced.
In case of co-located MIMO systems the channel conditions for the different Tx antenna elements are almost the same. Therefore you don’t experience a degradation of the number of streams due to the assumed MIMO interference, as in this case all the streams will be affected in the same way. Thus you have either all the streams transmitted or none at all.