The Wireless Packet Core--How Data Moves Through an LTE Network

Next Generation Communications Blog

The Wireless Packet Core--How Data Moves Through an LTE Network

By Mae Kowalke, TMCnet Contributor

The move toward 4G LTE is a seismic shift in mobile architecture inasmuch as it finally takes operators to an all-IP architecture. No more packet/TDM mix that adds complexity and slows down the network.

The rise in LTE also has meant a explosion in demand for packet core technology. Packet core revenue grew by 20 percent in the second quarter of this year compared with last year, for instance, according to research firm Dell’Oro.

The evolved packet core (EPC), as the LTE packet core is known, is both the brains and the brawn of LTE. Data goes from handsets across the backhaul network to the EPC, where the data is processed and then forwarded onto the Internet or another public or private network from the mobile provider.


Source: Alcatel-Lucent

The four main components of EPC for LTE networks are the:

  • Bearer channels
  • PDN gateway
  • Serving gateway
  • Mobility management entity

In fact, for more detailed information about EPC there is an interesting Alcatel-Lucent blog, What is the Evolved Packet Core and why should you care?, along with an informative podcast on the subject.

Bearer channels can be likened to individual private highways that specific users can use for their data services. A user might have a dedicated bearer channel for his voice service and at the same time he may have another separate bearer channel for his video or Internet service.

The PDN Gateway (PGW) is the IP anchor point and where bearer channels are established. The PGW provides the exit and entry point of traffic from the mobile provider’s network to the user equipment, according to the Alcatel-Lucent blog. It is the service edge of the mobile provider’s network, and much of the packet processing takes place there. For instance, packet inspection and filtering, policy enforcement and reporting all take place at the PGW.

The serving gateway (SGW) helps make it all mobile. The SGW routes and forwards user data packets through the bearer channels, and it also ensures that packets are continuously delivered even as the user changes location.

Finally, there is the mobility management entity (MME). The MME might be considered the brains of an EPC, for it issues and receives instructions related to the network, services and applications. Key responsibilities of the MME include assigning each UE to the proper SGW, coordinating the establishment of bearer channels, and assigning and optimizing network resources as the user moves geographically, as well as authentication and security management.

LTE takes mobility to an all-IP infrastructure, and a key part of LTE is the evolved packet core.

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