EPC: A new core network for the new LTE radio technology

Many new transmission facilities to the cellular towers are visible part of the LTE structure.


The second, invisible to the public, is equally important part: The technology and infrastructure with which these new LTE transmission facilities are operated and controlled, the so-called core network, changes radically. This core network for LTE (Engineered packet-based core network) and Evolved Packet Core Evolved Packet or designated system. It basically works like the normal Internet, the technical term for this technology is an IP-based network or English an all-IP network. But what does that mean and how this network is different from a GSM network or a UMTS network, so what is the new in it?

GSM, UMTS and LTE networks: the differences

Put simply, the current mobile phone networks were completely fixed, or in large part on voice telephony. The GSM network, the second generation of mobile phone was originally designed as a pure network; other functions such as SMS and data transmission were then gradually it. The UMTS network calls and sending large amounts of data as equal functions together. The core network is divided into a part of UMTS, which provided fixed channels for the transmission of telephone calls (circuit switched) and one of the different data sets – like the Internet – transported.

The LTE network has – like the Internet – the absolute data priority. Telephoning is thus only one of many sub-functions of data transmission. A development is reconstructed, which is advanced in the fixed network have further calls is no longer handled through a separate channel, but runs as a Voice over IP over the Internet.

Which then affects the manner in which the LTE core network works: It is anything from one terminal to the other terminal to the Internet technology – are transmitted – the Internet Protocol, or IP. Technically speaking, it is an IP-based network or an all-IP network.

This fundamental change in the net makes the data transmission speed – both for downloading and sending, as well as in the reaction times. The Australian IT specialist Stuart Corner says: It is not primarily be the new LTE data radio technology, which allows high speed jumps, but most of all the new core network.

Signaling data: By registering for the bill

The new network is allocated differently: Over a part of running the so-called signaling data – for example, the registration of the participant in the network, its verification and identification, the location of their mobile device – the other part of the so-called user data – ie services that he accepts the scheme as phone or mobile Internet.

Among the parts that manage the signaling data and edit include Management Mobility Entity, short MME (Management of the mobile units), the Home Subscriber Server, short HSS (Subscriber Server) and the Policy and Charging Rules Function, briefly PCRF (fees office).

Logs in the MME to the mobile device, and then is forwarded to a location which the services – manages – ie the data transmissions. The MME also retrieves the information about the customer at HSS – because they are deposited there, in the GSM and UMTS networks had this customer database the name of Home Location Register (HLR). The PCRF can – depending on the rate – to specific data flows from that terminal or declines; it calculates how much the service costs at the rate reserved by the customer and shall issue an invoice.

User data: designing services funneled through the net

The services themselves are carried out in the so-called SAE gateway. The acronym stands for System Architecture Evolution Gateway – and said in German as the main interface for the network. This gateway consists of two areas: First, since the serving gateway is – short SGW in German about services portal. There the user’s terminal is managed by the application at the MME continues. It remains registered so when the user switches between two cell towers or when switching from LTE to a different wireless technology. It takes the data packets received by the user sends – for example by surfing – and forwards it to the exit.

The output is referred to as PDN Gateway, which is German for Public Data Network Gateway as portal to the public networks. And that is its function: Here the data to other networks – other mobile networks, Internet – forwarded and received the input data for the terminal of customers and forwarded.