Written by: Johan Sköld, Magnus Lundevall, Stefan Parkvall and Magnus Sundelin

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The rapid, widespread deployment of WCDMA and an increasing uptake of third-generation mobile systems (3G) services are bringing network performance into sharp focus. Besides efficiently supporting an increasing number of subscribers, network systems should also give end-users a high-speed experience. To solve this equation, with its seemingly conflicting components, we need to understand performance and how it is measured. Likewise, present-day and evolving 3G systems should include features for increasing system performance.

New high-speed services and greater end-user demand for performance are driving the evolution. WCDMA Evolved supports an enhanced broadband experience of WCMDA systems. WCDMA Release 99 (Rel-99) services have evolved into WCDMA Releases 5 and 6 (Rel-5, Rel-6), which will reach commercial deployment by year-end 2005. Systems based on CDMA2000 are going through a similar evolution.

The authors describe the path to WCDMA Evolved and how it affects performance for end-users and operators.

Performance of 3G services
There is no single universal measure of performance for a telecommunications system. Indeed, end-users (subscribers) and system operators define good performance quite differently. On the one hand, end-users want to experience the highest possible level of quality. On the other hand, operators want to derive maximum revenue, for example, by squeezing as many users as possible into the system.

Until now, performance-enhancing features could generally either improve perceived quality of service (QoS) or system performance. But now, with WCDMA Evolved (Ericsson’s evolution of WCDMA for best-effort data services), one can potentially do both.

Mobile best-effort data services, such as web surfing and file downloads, have been available via packet data since the first release of WCDMA networks. They are a significant enhancement compared to 2G networks, and because the WCDMA specifications are evolving, packet-data support continues to improve. The first two phases of this evolution, commonly referred to as WCDMA Evolved, entail

• the introduction (in Rel-5) of high-speed downlink packet access (HSDPA); and
• the introduction (in Rel-6) of an enhanced uplink.
  
  Compared to earlier releases of WCDMA, these changes yield better data rates and shorter delay; that is, they greatly improve the service experience and system capacity.