: The MME contacts the HSS over the S6a interface to fetch authentication vectors. The MME and UE then mutually authenticate each other and activate NAS (Non-Access Stratum) security encryption.
: Connects the eNodeB to the S-GW for user-plane data transport.
: Uses the Diameter protocol for subscription management and authentication. The MME sends an Update Location Request to the HSS, which responds with the user's subscription data. : The MME contacts the HSS over the
The EPC architecture consists of several key network elements: ScienceDirect.com MME (Mobility Management Entity):
Connects the eNodeB to the MME for control-plane signaling. : Uses the Diameter protocol for subscription management
Acts as a local mobility anchor for data packets as the UE moves between eNodeBs (base stations). It bridges the radio network to the EPC. P-GW (Packet Data Network Gateway):
Links the MME to the HSS using the Diameter protocol for authentication and profiling. 3. Step-by-Step LTE Call Flows and Signaling 1. The Initial Attach and Default Bearer Setup Acts as a local mobility anchor for data
These are the standardized connections between nodes.
Downlink data arriving at the P-GW is forwarded to the S-GW. Because the device is idle, the S-GW has no active tunnel to an eNodeB.
An is a virtual tunnel established between the UE and the P-GW to provide a specific QoS for traffic.