An Introduction to 5G

2Architecture of the Core Network

This is the first of two chapters that lay out the system architecture of 5G. We will begin by reviewing the architecture of the LTE evolved packet core, partly because it is still used by early 5G roll‐outs, and partly because it will act as an introduction to the 5G core. We will then move onto the 5G core network itself, covering its architecture and the roles of its most important network functions.

The main signalling protocol in the 5G core network is version 2 of the Hypertext Transfer Protocol (HTTP/2). That protocol is very different from the ones used by older mobile telecommunication systems, so we will review the protocol and provide some examples of the resulting signalling procedures. Several specifications are relevant to this chapter, but the most important is the stage 2 description of the 5G core network, Technical Specification (TS) 23.501 [1].

2.1 The Evolved Packet Core

2.1.1 Release 8 Architecture

Figure 2.1 shows the most important elements in the LTE evolved packet core (EPC) [2]. The different icons represent network elements that are used for data transport, signalling and information storage. An individual network might contain several instances of each one, both for geographical organization and for redundancy.

Figure 2.1 Architecture of the evolved packet core.

Source: Adapted from 3GPP TS 23.401.

The interfaces ...