The LTE/SAE Deployment Handbook

Chapter 12

Planning and Deployment of SAE

Jukka Hongisto and Jyrki T. J. Penttinen

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, ...