Evolved Packet System (EPS): The LTE and SAE Evolution of 3G UMTS

Preface

With more than two billion customers, there is no doubt that 2G GSM and 3G UMTS cellular technologies are a worldwide success, adopted by most countries and network operators. The 3G UMTS technology has significantly evolved since the first declination. The first release of the standard, published in 1999, was mostly oriented towards dedicated channel allocation, and circuit-switched service support. Later on, the standard evolved to high-speed packet radio interface for downlink transmission (HSDPA for High Speed Downlink Packet Access) and uplink transmission HSUPA as a clear orientation towards IMS (IP Multimedia Subsystem) and IP-based services.

EPS (Evolved Packet System) represents the very latest evolution of the UMTS standard. EPS is also known by other acronyms related to technical study items being worked on at 3GPP standard committees: LTE (Long Term Evolution), which is dedicated to the evolution of the radio interface, and SAE (System Architecture Evolution), which focuses on Core Network architecture evolution.

Although still a 3G-related standard, EPS proposes a significant improvement step, with a brand new radio interface and an evolved architecture for both the Access and the Core Network parts. The two major disruptions brought by EPS are:

• Improved performances – characterized by a spectrum efficiency which is twice as large as HSDPA/HSUPA.
• A packet-only system – resulting in a unified and simplified architecture.

EPS is specified as part of the 3GPP ...