LTE Association occurs by exchange of control packets between the ENB and UE.


Initially, the UE sends the RRC_CONNECTION_REQUEST packet to the ENB. 

The ENB in response sends an RRC_CONNECTION_SETUP packet back to the UE. 

The association is completed when the UE sends a CONNECTION_SETUP_COMPLETE packet back to the ENB.


This process can be understood using NetSim's packet trace file.


 Note: LTE Association procedure happens also after an event of Handover.


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