Look the difference with and without Massive MIMO
It is not nevessary to change PCI, since ARFCN is different
How can the UE handle MIMO 4x4 and carrier aggregation with a limited number of antennas? How can it work in real life?
In short MIMO will be more beneficial as it’s provides you gain in both coverage and capacity, As we know due to mimo gains we will able to improve our Channel quality and that helps you to reduce PRB utilisation and also PDCCH utilisation, as PDCCH utilisation reduced so your pdsch capacity increased . So in my opinion MIMO is better
Can aggregate two CCs having different MIMO? One carrier with Single tX and another Carrier with 2T2R?