HSPA Evolution – Boosting the performance of mobile broadband access

HSPA Evolution – Boosting the performance of mobile broadband access

Written by: Johan Bergman, Mårten Ericson, Dirk Gerstenberger, Bo Göransson, Janne Peisa and Stefan Wager

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This article presents the main concepts of HSPA Evolution (high-speed packet access evolution), which is currently being standardized by 3GPP in Releases 7 and 8 of the WCDMA specification. The aim of HSPA Evolution is to further improve the performance of WCDMA systems through higher peak rates, lower latency, greater capacity, increased battery times, better support for VoIP, and improved multicast/broadcast capabilities.

The authors briefly cover MIMO, higher-order modulation, protocol optimizations, optimizations for VoIP, improved multicast/broadcast, and advanced receivers. They also describe a variety of features (such as multicarrier operation) that will boost performance even further in subsequent releases of the WCDMA specification.

Introduction

Today, 84% of all reported global cellular subscribers make calls via radio access technology specified by the Third Generation Partnership Project (3GPP). This signifies that WCDMA is the predominant third-generation (3G) radio network technology, and as such, represents a substantial economy of scale.

In addition, the recent introduction of high-speed packet access (HSPA, 3GPP Release 6) has significantly improved the performance of packet data traffic in Ericsson products - on the downlink (HSDPA) 14Mbps, and uplink (E-UL), 1.4Mbps, giving users a mobile broadband experience that is on par with ADSL; and given rise to large increases in packet data traffic - packet data is now the principal type of traffic in 3G networks.

Ericsson continues to build on this success by enabling operators who have deployed WCDMA to boost their system performance through software upgrades. The HSPA Evolution specification (3GPP Releases 7 and 8) introduces new features that support higher data bit rates, lower latency, greater capacity, better support for VoIP, and improved support for multicast services. Release 7 of the specification introduces:

• higher-order modulation (HOM);
• multiple input, multiple output (MIMO);
• continuous packet connectivity (CPC);
• layer-2 enhancements;
• enhanced CELL_FACH;
• multicast/broadcast single-frequency network (MBSFN); and
• advanced receivers.

In addition, 3GPP is considering multicarrier operation, downlink-optimized broadcast (DOB) and more advanced receivers for future releases of the specification. These new concepts will yield substantially higher peak data bit rates as well as greater spectral efficiency and voice-over-IP (VoIP) capacity. In Release 8, for example, the peak data bit rates will reach up to 42Mbps in the downlink and 11Mbps in the uplink (per 5MHz carrier).

This article deals primarily with the features 3GPP has added to HSPA in Releases 7 and 8 of the WCDMA specification. It also touches on candidate techniques for further evolving the specification in future releases.

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