Chapter 12
Planning and Deployment of SAE
12.1 Introduction
This chapter describes how LTE can be supported by the packet core network of LTE/SAE. The chapter concentrates on 3GPP release 8 LTE/SAE architecture and the Evolved Packet Core (EPC), and it presents potential migration steps from the existing 2G/3G PS core towards fully compatible Rel-8 EPC.
12.2 Network Evolution from 2G/3G PS Core to EPC
12.2.1 3GPP R8 Requirements for LTE Support in Packet Core Network
3GPP Release 8 defines a new EPC for LTE access. The EPC can also be used for other access technologies like GERAN, UTRAN and CDMA2000. Figure 12.1 shows the standard Release 8 architecture with the relevant interfaces between the logical entities.
Figure 12.1 3GPP R8 architecture for LTE/SAE.
The Mobility Management Entity (MME) is the equivalent of the SGSN in 2G/3G GPRS networks. In the LTE/SAE network, the MME is a pure control-plane element. It initiates a direct tunnel between the eNodeB and Serving Gateway in order to deliver the user-plane traffic.
According to 3GPP Release 8, the mobile gateway functionality is divided into the Serving Gateway (S-GW) and the Packet Data Network Gateway (P-GW) functionalities. These S-GW and P-GW functionalities can be implemented in the same physical node or in two separate entities. They are connected logically via an open S5 interface, ...
