The establishment of a Packet Data Network (PDN) connection in an LTE network involves a multi-step process that ensures the User Equipment (UE) can access external networks like the internet. Here's an overview:
- UE Attaches to the LTE Network: The UE initiates by attaching to the LTE network, undergoing authentication and security procedures, and setting up a default EPS bearer.
- Create a PDN Connection Request: The UE sends a PDN connectivity request to the network for the type of PDN connection it wishes to establish.
- PDN Gateway (P-GW) Selection: The request is forwarded to the Mobility Management Entity (MME), which selects an appropriate P-GW based on the request and policies.
- IP Address Allocation: The P-GW allocates an IP address to the UE. This can be IPv4, IPv6, or both, depending on the network and UE capabilities.
- EPS Bearer Establishment: The network establishes an EPS bearer between the UE and the P-GW for the requested PDN connection, along with any necessary dedicated bearers for specific QoS.
- Sending the PDN Connectivity Accept: The P-GW sends a PDN connectivity accept message to the UE, including the IP address and details of the established bearers.
- Data Communication: With the PDN connection established, the UE can start sending and receiving data packets, accessing the internet or other external networks.
This process involves coordination between the UE, eNodeB, S-GW, P-GW, and MME, providing the necessary resources and routing for internet access.