18 - System Architecture Evolution

Abstract

This chapter provides an overview of the System Architecture Evolution (SAE) work in 3GPP and explores the core network used by WCDMA/ High-Speed Packet Access (HSPA)The chapter describes the system architecture of WCDMA/HSPA and Long-Term Evolution (LTE), their connections, similarities, and differences. The term system architecture describes the allocation of necessary functions to logical nodes and the required interfaces between the nodes. The system architecture is divided into a radio-access network (RAN) part and a core-network part. The chapter discusses the functional split between radio access network and core network. For WCDMA/HSPA, the philosophy behind the functional split is to keep the core network unaware of the radio access technology and its layout. This means that the RAN should be in control of all functionality optimizing the radio interface and that the cells should be hidden from the core network. As a consequence, the core network can be used for any radio access technology that adopts the same functional split.