W-CDMA Guide, Meaning , Facts, Information and Description
W-CDMA (Wideband Code Division Multiple Access), a wideband spread-spectrum 3G mobile telecommuncation air interface that utilizes code division multiple access (or CDMA the general multiplexing scheme, not to be confused with CDMA the standard), is a 3G mobile communications standard allied with the GSM standard. W-CDMA is the technology behind UMTS (aka 3GSM). Networks using W-CDMA are a form of cellular network.
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2 Misconceptions 3 Real-World Implementations 4 Technology 5 Comparison with other standards |
W-CDMA was developed by NTT DoCoMo as the air interface for their 3G network FOMA. Later NTT Docomo submitted the specification to ITU as a candidate for the international 3G standard known as IMT-2000. The ITU eventually accepted W-CDMA as part of the IMT-2000 family of 3G standards. Later, W-CDMA was selected as the air interface for UMTS, the 3G successor to GSM.
In the mobile phone world, the term CDMA can refer to either the
Code Division Multiple Access spread spectrum multiplexing technique,
or the CDMA family of standards developed by Qualcomm, including cdmaOne (or IS-95) and CDMA2000 (or IS-2000).
The CDMA multiplexing technique existed long before Qualcomm used it for its IS-95 protocol. However, this protocol is now widely referred to as "CDMA" because for its principal characteristic of using the CDMA multiplexing scheme to share multiple connections over the same spectrum, as opposed to other spectrum division schemes (eg. GSM's TDMA).
W-CDMA also uses the CDMA multiplexing technique, and has many similarities to the Qualcomm standards. However W-CDMA is more than a multiplexing standard. W-CDMA is a complete set of specifications, a detailed protocol that defines how a mobile phone communicates with the tower, how signals are modulated, how datagrams are structured, etc.
In summary:
The world's first commercial W-CDMA service, FOMA, was launched by NTT DoCoMo in Japan in 2001. FOMA is not compatible with UMTS.
J-Phone Japan (now Vodafone) soon followed by launching their own W-CDMA based service, now branded "Vodafone Global Standard" and claiming UMTS compatibility (although as of 2004 this is debatable).
Beginning in 2003, Hutchison Whampoa 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 have committed to an actual timeline. Some of them have begun launching UMTS networks at the end of 2003.
Vodafone launched several UMTS networks in Europe in February 2004. Vodafone also has plans to launch UMTS networks in other countries, including Australia and New Zealand.
AT&T Wireless; has announced plans to launch a UMTS service in the United States by the end of 2004.
TeliaSonera opened W-CDMA service in Finland October 13th 2004 with speeds upto 384 kbit/s. Availability only in main cities. Pricing is approx. 2€/MB.Press release
Please see UMTS for more info.
W-CDMA may use unpaired or paired spectrum, though the current implementations of W-CDMA (i.e. FOMA and UMTS) all use a pair of 5MHz spectrum, one for uplink and one for downlink. See Spread spectrum for more information.
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 commonly known as W-CDMA (e.g. FOMA, UMTS) is not compatible with the family of standards commonly known as CDMA (e.g. IS-95 and cdma2000).
This is an Article on W-CDMA. Page Contains Information, Facts Details or Explanation Guide About W-CDMA Brief History
Misconceptions
Despite the similarity in name, W-CDMA has very little to do with CDMA. How little depends on the point of the viewer.Real-World Implementations
Technology
Comparison with other standards