W-CDMA

Table of contents

1 Preface 2 General Information 3 Real-world Implementations 4 Technology 5 Comparison with other standards

Preface

This page explains the technological aspects of W-CDMA (the technology), common to UMTS, FOMA and J-Phone. For other aspects (business, users or political) surrounding the various W-CDMA networks or standards, or issues specific to those variants, please use their respective pages.

General Information

W-CDMA (Wideband Code Division Multiple Access), the wideband implemenation of the CDMA multiplexing scheme (not to be confused with the CDMA standard, which is techically known as IS-95), is a 3G mobile communications standard allied with the GSM standard. W-CDMA is the technology behind UMTS.

W-CDMA technology is marketed under the moniker of 3GSM, reflecting the 3G nature of the technology and the GSM standard which it is designed to succeed.

Real-world Implementations

The world's first commercial WCDMA service FOMA was launched by NTT DoCoMo in Japan in 2001.

J-Phone Japan soon followed by launching their own W-CDMA based service called J-Phone.

Beginning in 2003, Hutchinson Whompoa gradually launched their upstart UMTS networks (simply called 3) worldwide.

Most western european GSM providers plan to offer UMTS sometime in the future, though few could commit to an actual timeline. Some of them has begun launching UMTS networks at the end of 2003.

Vodafone has launched several UMTS netwroks in Europe in February, 2004.

AT&T Wireless has announced plans to launch UMTS service in the United States but has yet to deploy a commercial service.

Please see UMTS for more info.

Technology

W-CDMA may use unpaired or paired spectrum, though the current implementations of W-CDMA (i.e. FOMA, J-Phone and UMTS) all use a pair of 5MHz spectrum, one for uplink and one for downlink. See Spread_spectrum for more information.

Comparison with other standards

In contrast to CDMA2000, which can use multiple 1.25 MHz carriers, W-CDMA uses 5MHz channels.

In the ITU's IMT-2000 standard, W-CDMA is known as CDMA Direct Spread.

The family of standards commly known as W-CDMA (e.g. FOMA, UMTS, J-Phone) is not compatible with the family of standards common known as CDMA (e.g. IS-95 and cdma2000).