S-GW-C Serving Gateway Control Plane Function
The Serving Gateway Control Plane Function (S-GW-C) is a component of the Evolved Packet Core (EPC) architecture in Long-Term Evolution (LTE) and 5G networks. It plays a crucial role in the control plane of the network, handling signaling and control messages for the establishment, maintenance, and termination of data sessions between the User Equipment (UE) and the core network.
Here's a detailed explanation of the S-GW-C and its functions:
Serving Gateway (S-GW):
The S-GW is a key network element in the LTE and 5G architecture responsible for routing and forwarding user data packets between the UE and the Packet Data Network Gateway (P-GW). In the control plane, the S-GW performs various control functions through the S-GW-C.
Control Plane Function:
The control plane of a cellular network is responsible for managing the signaling and control procedures necessary for establishing, modifying, and terminating communication sessions between network elements and user devices.
S-GW-C Functions:
The S-GW-C performs several important functions in the control plane:
a. Session Management: The S-GW-C handles the session management procedures, which include the establishment, modification, and termination of data sessions between the UE and the core network. It coordinates with other network elements, such as the Mobility Management Entity (MME), to exchange signaling messages and manage the session-related information.
b. Mobility Management: The S-GW-C is involved in mobility management, enabling the UE to move seamlessly between different network areas or access technologies. It assists in procedures such as tracking area updates, handovers, and context transfer between the old and new S-GWs during a mobility event.
c. Quality of Service (QoS) Control: QoS control is essential for ensuring that different types of data traffic receive the appropriate level of service based on their priority and requirements. The S-GW-C participates in QoS management by implementing policies and rules for traffic classification, prioritization, and enforcement, based on operator-defined parameters.
d. Policy Enforcement: The S-GW-C enforces the operator's policy rules regarding access control, charging, and service restrictions. It checks the policy and charging rules associated with a particular user or session and ensures that the appropriate policies are enforced, allowing or restricting access to certain services or resources.
e. Charging Control: The S-GW-C supports charging control functions by gathering session-related information, such as data volume, duration, and service usage, for billing purposes. It communicates with the Charging Gateway Function (CGF) to provide the necessary charging data and reports.
f. Interworking: In some scenarios, the S-GW-C may also perform interworking functions between different generations of cellular technologies, such as LTE and 5G, or between different network architectures. It facilitates seamless communication and connectivity between devices and network elements that operate on different technologies or protocols.
Interaction with Other Network Elements:
The S-GW-C interacts with various network elements to perform its functions effectively. It communicates with the MME for session management and mobility-related procedures, the P-GW for data forwarding and charging control, and other entities like the Home Subscriber Server (HSS) for subscriber authentication and authorization.
In summary, the S-GW-C is an integral part of the Evolved Packet Core architecture, responsible for managing the control plane functions associated with session management, mobility management, QoS control, policy enforcement, charging control, and interworking. Its role is crucial in ensuring seamless and efficient communication between the UE and the core network in LTE and 5G networks.