The outcome of the 3GPP SAE (system architecture evolution) technical study and specification work is a set of standards that specifies the evolution of the packet core network for GSM/GPRS and WCDMA/HSPA to an all-IP architecture and enables a feature-rich ‘common packet core’ for radio accesses developed within 3GPP and also by other standardization fora. This common core is referred to as EPC (evolved packet core) and the full system is known as EPS (evolved packet system) which includes support for 3GPP radio access technologies (LTE, GSM and WCDMA/HSPA) as well as support for non-3GPP access technologies. Unlike its predecessor, EPC provides support for multiple access technologies and provides for mobility between them, allowing end-users to move between, for example LTE, WLAN and other 3GPP and non-3GPP accesses. The architecture, in comparison to the one used for 2G/3G packet core is also optimized for efficient payload handling; a so-called ‘flatter’ architecture. In addition to these benefits, EPC provides updates to all of the already established parts of the 2G/3G packet core network, for example security, connectivity management and so on. In short, the SAE work has prepared the core network for the mobile broadband revolution, through the specification of EPC.

The standards produced by the SAE work item can be perceived as complex, as they span several thousands of pages. This makes it difficult for any individual not involved in the development of the standard to find time to examine these specifications in detail. Many people in the industry have often mentioned to us that the system spans a multitude of specifications and it would be beneficial for the readers within the telecom industry to have a single source description of the new packet core. This book is an answer to this demand; a concise and comprehensive description of the different aspects of the SAE standards for several different reader groups with interests for mobile communications industry.

Our goal is that reading this book will improve the overall understanding of the network architecture and protocols included in the EPC system. It is, however, significantly more than just annotated 3GPP specifications. It provides a detailed analysis of the network architecture, nodes and protocols involved in EPC. In addition we have described the main reasons why certain decisions were taken in the standards bodies; the context of many of these technical decisions is often imperative to a full understanding of how the architecture fits together. This is extra knowledge that we have tried to capture for the reader through our experiences in the standardization process of the SAE work item.

This book provides a thorough grounding for anyone wishing to learn about how operators and other actors in the industry may implement the EPS and also the different migration paths that may be taken. It also provides an overview of the services that will be utilizing LTE and EPC.

Readers who are already familiar with EPC, LTE or IMS will hopefully also benefit substantially from this book as it identifies how these concepts fit together in order to deliver the promise of mobile broadband. For example, readers familiar with IMS will gain a new depth of insight into how voice services will fit together with the new network architecture and protocols., Appendix A covers the different specifications that are relevant for SAE. It should be noted, however, that this book is not just for readers interested in 3GPP specifications, but it also covers the implementation scenarios for 3GPP2 and also interconnection with non-3GPP accesses such as WLAN, WiMAX or fixed access. Readers interested in only one access technology, or indeed interested in only one protocol, will also gain a good depth of understanding of how their part fits in with the overall network architecture.

We have divided this book into five different parts, each of which contains several chapters.