Question: What is the primary purpose of the S1 Application Part (S1AP) protocol over the S1 interface in the Evolved Universal Terrestrial Radio Access Network (E-UTRAN)?
Option 1: To facilitate transparent conveyance of messages between the EPC and UE, handle general E-UTRAN procedures from the EPC, separate UE for mobile-specific signalling, transfer non-access signalling, request E-RABs, and perform mobility functions.
Option 2: Exclusively to manage User Equipment (UE) mobility within the E-UTRAN, without interacting with the EPC for other signalling purposes.
Option 3: Solely to provide Access Stratum (AS) services, such as setting up E-RABs, without handling general E-UTRAN procedures or UE-specific signalling.
Option 4: To interpret and process all messages between the EPC and UE before forwarding them over the S1 interface.
Explanation: The correct answer is Option 1 because it accurately reflects the comprehensive role of the S1AP protocol. It highlights the protocol's capability to handle a wide range of functions including facilitating E-UTRAN procedures from the EPC, managing UE-specific signalling, transferring non-access signalling, requesting E-RABs, and performing mobility functions.