Written by: Bo Berglund, Michael Englund and Jonas Lundstedt

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The market for WCDMA has taken off in several regions around the world. Europe, East Asia and Australia, for example, are each reporting accelerated growth in subscriber uptake. Many operators, after a successful rollout of coverage, are now also offering high-quality networks that carry steadily increasing loads of voice and data traffic.

Three 3G standards are competing for subscribers: WCDMA, CDMA2000 and TD-SCDMA. To sustain continued growth in regions where customers are accustomed to excellent 2G handsets, services and high-speed fixed broadband access, operators of 3G networks must offer even better services and greater mobility. Moreover, they must keep their tariffs competitive. Consequently operators are very interested in peak performance, capacity, and cost-effectiveness.

This article discusses how Ericsson's new, third release of its WCDMA macro radio base stations (RBS) capitalize on advances in technology to improve the architecture of the RBS node to meet the challenges described above and to help operators target new business opportunities. The new design enables operators to double node capacity, increase coverage, simplify maintenance, and dramatically reduce power consumption. The combined effect of these enhancements yields considerably lower capital expenditures (CAPEX) and operating expenses (OPEX) in the radio access network (RAN).

The authors briefly review Ericsson's WCDMA RBS development strategy, giving examples of important design choices and explaining how the architecture has evolved to fit new market requirements and exploit advances in technology. In particular, they discuss the improved RBS architecture, advances in multicarrier power amplifier (MCPA) linearization technology, and design aspects of importance to high-speed downlink packet access (HSDPA) and the enhanced uplink (E-UL). The authors also introduce Ericsson's newest macro base station members of the RBS 3000 family.

Background
Ericsson's strategy for 3G network development is to release products and features in accordance with customer needs at different phases of network rollout (Figure 1). The most important customer needs during the first phase, commercial launch, are

• rapid rollout (mainstream site concept);
• efficient training of staff;
• stability; and
• future-proof investment (backward and forward compatibility).