Evolved Packet Core in LTE

Many people in the mobile industry are unaware that LTE, the radio Cinderalla, also has an ugly sister, called EPC (Evolved Packet Core - originally it was called SAE).

Many things about EPC are actually worthy - "flatter" IP network, lower latency, the ability to mesh between base stations, getting rid of a lot of other legacy equipment like SGSNs and GGSNs and so forth.

However, there is one thing that appears to be missing - the option for local offload of traffic. Everything is still backhauled via various gateway and policy boxes. It's not possible to say "that's a 3GB web video download - just short-circuit it straight to the Internet". It still has to go through the core network.

If I'm understanding this correctly, this has a couple of important implications:

- Roaming traffic will still need to be backhauled via the home network, even if it's just plain-vanilla Internet data. You can't just dump it to the web in the visited country. So you can forget about LTE roaming being able to compete with local WiFi (or a locally-acquired LTE SIM) on price, because there's still a huge extra overhead of network elements and unnecessary transport involved.
- In LTE femtocells, the option for "split tunnels", for example to offload web traffic or operator services like IPTV in the home gateway, or DSLAM / cable headend, won't work. Again, the traffic needs to go through the mobile EPC core. You can also forget about using LTE instead of WiFi for UPnP or other types of home networking via a femto - the traffic will need to be "tromboned" in and out.