Question: What is the primary purpose of the S1 Application Protocol (S1AP) as specified in 3GPP TS 36.413, in the context of Evolved Universal Terrestrial Radio Access Network (E-UTRAN)?
Option 1: To manage user data transmission over the S1 interface for E-UTRAN.
Option 2: To define radio network control plane signalling over the S1 interface for E-UTRAN.
Option 3: To establish and manage bearer resources for voice services in E-UTRAN.
Option 4: To provide security protocols for S1 interface communication in E-UTRAN.
Explanation: The correct answer, Option 2, accurately reflects the role of S1AP as specified in 3GPP TS 36.413. S1AP is crucial for controlling and managing aspects of the radio network over the S1 interface, which includes signaling related to mobility, session management, and more, all of which are part of the control plane. This distinction is important because, in telecom networks, control plane signaling (e.g., setup, modification, and release of sessions) is separate from user plane functions (e.g., data transmission), highlighting the significance of S1AP in E-UTRAN’s operational efficiency and functionality.