How does an UE come to know that resources have been scheduled in secondary cell as well ?

Question

An UE configured for carrier aggregation, may have different radio channel conditions for primary and secondary cells.
I meant to say, primary cell may have strong signal strength at the same time UE may observed secondary cell(s) not too good.
In this case, does the same modulation and coding schemes used for primary and secondary or may use different coding and modulation schemes for different channels for the same sub frame?

Answer 1

In LTE-A UE performs attach at primary cell and gets the secondary cell information through rrc reconfiguration. Then eNB can activate/deactivate secondary cell by sending Mac ce to UE. ENB can perform scheduling for secondary cell when it is active. ENB can perform cross carrier scheduling or with out cross carrier scheduling.
In cross carrier scheduling UE needs to monitor Pdcch at pcell to know the scheduling of pcell and scell.
Without cross carrier scheduling, UE need to monitor pdcch at pcell as well as at active scell to know the scheduling.