Ⅰ、NGAP stands for NG Application Protocol, which is an application protocol between the 5G core network (5GC) and the radio access network (NG-RAN) to ensure efficient and secure messaging in the network.
Ⅱ、NGAP Architecture As shown in Figure 1 NGAP is built on the N2 interface; this interface connects the gNB (RAN) and the AMF (core network) to help accomplish the transmission and exchange of control plane signaling messages.
Ⅲ、The interface protocol layer is included：
Application Layer:This layer contains the NGAP protocol entities and is responsible for generating and processing NGAP messages.
Transport Layer: This layer is responsible for reliably delivering NGAP messages between the gNB and the AMF, and it usually uses the SCTP (Stream Control Transmission Protocol) protocol.
Security Layer: This layer is responsible for providing security services for NGAP messages, such as authentication, integrity protection and confidentiality. It typically uses the TLS (Transport Layer Security) protocol.
Ⅳ、IMPORTANCE 5G can be visualized as a high-speed train through which packets are transported; NGAP ensures smooth boarding, seamless switching between sites (units), and efficient resource allocation while keeping everything safe and smooth. Without it 5G's promise of ultra-high speeds, ultra-low latency and diverse services would be just a dream.
Ⅴ、 How it works NGAP operates on a dedicated line N2 interface, connecting the radio access (gNB) to the core network (AMF). This is the dedicated communications channel for important updates and instructions to transmit a range of programs and messages, while the NGAP manages everything from subscriber authentication to mobility and service activation.
Ⅵ、Included in the related entities：
gNB:5G network base station, which is responsible for providing wireless access to UEs (user equipment)；
AMF(Access and Mobility Management):responsible for managing UE mobility and providing access to network services；
UPF(User Plane Functions): responsible for forwarding user-plane data between the gNB and the core network
Ⅶ、Features and Functions
① NAS signaling:NGAP facilitates NAS (Non-Access Layer) signaling for user authentication, mobility and bearer service management; ensuring secure access and a seamless service experience across different wireless access technologies.
② Separation of the control plane: This can be thought of as a dedicated traffic channel. the NGAP maintains a clear separation between the control plane (signaling) and the user plane (data). This allows for efficient resource management and scalability, processing information flows without interfering with data traffic.
③ Security mechanisms:NGAP employs strong security measures such as mutual authentication and integrity protection. This guards against network threats and ensures secure communications, protecting network integrity and user data.
④ Flexibility and Scalability:NGAP is designed to be flexible and adaptable to emerging needs. Its modular architecture allows for easy integration of future enhancements and new services, paving the way for B5G evolution and unforeseen advancements.
⑤ User Equipment (UE) Management: NGAP establishes and manages the UE context that handles user authentication, registration and mobility procedures. It ensures smooth onboarding, seamless switching and continuous connectivity as users move through the network.
⑥ Wireless Resource Management:NGAP helps to allocate and manage radio resources for UEs, optimizing network performance and ensuring fair and optimal resource utilization for each connected device.
⑦ Service Management:NGAP can establish and manage a variety of services for UEs, seamlessly facilitating cutting-edge applications such as data, voice, video, IoT connectivity, and even AR/VR.
⑧ Mobility Management:NGAP facilitates seamless switching between different RATs (Radio Access Technologies) and gNBs (Base Stations), thus guaranteeing uninterrupted connectivity for mobile users and ensuring that there are no dropouts or service interruptions.
