Wideband Code Division Multiple Access (WCDMA) is a 3G technology that increases data transmission rates in GSM systems by using the CDMA air interface instead of TDMA. It was adopted as a standard by the ITU under the name 'IMT-2000 direct spread' and is fully compliant with IMT-2000. It is air the interface technology for standards in the 2GHz bandwidth (the IMT-2000 core band), known as Association of Radio Industry Businesses (ARIB) in Japan and Universal Mobile Telecommunication System (UMTS) in Europe.

Ericsson was the first to develop WCDMA technology. The company delivered an experimental WCDMA system to NTT DoCoMo in Japan back in 1998.

WCDMA is expected to account for more than 85% of mobile subscriptions worldwide today. Like GSM and EDGE, it is a fully standardized global solution. It has open interfaces and it offers enhanced voice and data capacity and peak data rates faster than most dial-up services and average rates consistently greater than GSM/GPRS and EDGE.

WCDMA's full interoperability between terminals and handset will be responsible for its success as for the mass take-up of a technology dual mode handsets and GSM/WCDMA networking is vital.

WCDMA also enables the operators to offer service portability and enhanced international roaming benefits to subscribers, thereby commercially benefiting the customers from the wide acceptance of WCDMA. Australian operator Telestra, recently, announced that it is migrating from CDMA to WCDMA 3G services. KTF of Korea will introduce WCDMA technology in the first half of 2007. H3G in Australia and Vivo in Brazil are also planning to switch to WCDMA networks.

Why will it Work
WCDMA is economically workable because it provides most cost effective means of adding significant capacity to both voice and data services. Operators are expected to generate higher revenues as high bandwidth and low latency of WCDMA contributes to a higher quality user experience, which is crucial for the same. Subscribers are expected to take up more advanced data services and WCDMA will provide fast access that users will demand.

WCDMA has a global standard based on an open architecture, with all the advantages of economies of scale and global roaming. Although CDMA2000 1X, which is a narrowband technology can also evolve to 3G speeds, it is not an open end-to-end solution and does not enjoy the benefits of WCDMA.

What's Next
High-speed downlink packet access (HSDPA) is an evolution of WCDMA, optimized for packet-switched data applications. It provides impressive enhancements over WCDMA on the downlink promising 14.4 Mbps peak data rates, which in turn results in a better end-user experience.

HSDPA service enables subscribers to receive emails with large attachments, surf the Web or download multimedia or text files faster than ever. With HSDPA the operators can increase their capacity three- to five-fold over WCDMA.

The first HSDPA network was launched in the US in December 2005. By the end of January 2006, there were 9 announced trials around the world and more than 50 other HSDPA networks planned or deployed.

Another evolution is happening in the standards development, which is high-speed uplink packet access (HSUPA). It extends the benefits of HSDPA to the uplink and will support up to 5.76 Mbps peak rates, further improving the end user experience. It will enable lower latency services such as VoIP, multiplayer interactive gaming, push-to-talk etc, and will also provide end users with a DSL-like experience. The first HSUPA deployments are expected in 2007. WCDMA will continue to evolve with the goal to increase network capacity, giving connectivity a whole new meaning.

Sonia Sharma
sonias@cybermedia.co.in