This feature shall allow in future to simulate an arbitratry number of UEs connected to an other arbitrary number of cells.
Therefore each RF-frontend (also called RU) needs to be configured for one specific cell.
In case of handover of a UE from one cell to another cell, it needs to switch RUs accordingly (TODO).
There has to be a 1-to-1 mapping between RUs and cells.
Each UE will be assigned to one of the defined cells.
Initially all UEs are assigned to cell 0.