LTE and the Evolution to 4G Wireless: Design and Measurement Challenges, 2nd Edition

Chapter 5

System Architecture Evolution

Development of the LTE air interface has been closely linked within 3GPP to the work on a new packet-switched system architecture initially called the System Architecture Evolution (SAE). This architecture comprises the LTE evolved UMTS radio access (E-UTRA) and evolved UMTS radio access network (E-UTRAN) as well as a new evolved packet core (EPC) network. The overall system goes by the name enhanced packet system (EPS) or LTE/SAE; these terms are often used interchangeably. The new core network is variably called the SAE/EPC, the SAE core network, or simply the EPC.

This chapter briefly introduces the EPS requirements, functions, and services. For more comprehensive information, refer to the latest versions of the standards documents listed below and at the end of this chapter.

Reference Documents

The EPS architecture supports heterogeneous access-system mobility within 3GPP and non-3GPP access systems, including fixed access systems. Architectural enhancements relating to 3GPP access systems including the E-UTRAN, legacy UTRAN, and GERAN are detailed in 23.401 [1]. Similarly, architectural enhancements relating to non-3GPP access systems including 3GPP2 cdma2000 and wireless LAN (WLAN), are detailed in 23.402 [2]. Functional descriptions are also included in 36.300 [3]. The focus of this chapter is the overall EPS architecture supporting 3GPP E-UTRAN access including E-UTRAN mobility. The remaining access systems including interworking ...