Question: During an S1 Handover in a 3GPP network, what is the primary purpose of the target MME sending the received {NH, NCC} pair to the target eNB within the S1 HANDOVER REQUEST message?
Option 1: To authenticate the UE's identity for billing purposes
Option 2: To enable the target eNB to compute KeNB for secure communication with the UE
Option 3: To inform the target eNB about the source cell's AS algorithms for handover optimization
Option 4: To update the target eNB's stored list of neighboring cell IDs
Explanation: The correct answer is Option 2 because the {NH, NCC} pair is crucial for the target eNB to derive the KeNB (Key for eNB) using the key derivation function defined in Annex A.5, incorporating the fresh {NH, NCC} pair, target PCI, and frequency EARFCN-DL. This KeNB is essential for securing the communication between the UE and the target eNB after the handover.