ITU 3G definition, aka IMT2000

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Wikipedia entry on 3G:

3G technologies are an answer to the International Telecommunications Union's IMT-2000 specification. Originally, 3G was supposed to be a single, unified, worldwide standard, but in practice, the 3G world has been split into four camps.

UMTS (W-CDMA)
UMTS (Universal Mobile Telephone System), based on W-CDMA technology, is the solution generally preferred by countries that used GSM, centered in Europe. UMTS is managed by the 3GPP organization also responsible for GSM, GPRS and EDGE.

FOMA, launched by Japan's NTT DoCoMo in 2001, is generally regarded as the world's first commercial 3G service. However, while based on W-CDMA, it is not generally compatible with UMTS (although there are steps currently under way to remedy the situation).

CDMA 2000
The other significant 3G standard is CDMA2000, which is an outgrowth of the earlier 2G CDMA standard IS-95. CDMA2000's primary proponents are outside the GSM zone in the Americas, Japan and Korea. CDMA2000 is managed by 3GPP2, which is separate and independent from UMTS's 3GPP. The various types of transmission technology used in CDMA2000 include 1xRTT, CDMA2000-1xEV-DO and 1xEV-DV.

CDMA 2000, has a data rates of 144 kbit/s to over 3 Mbit/s. Adopted by the International Telecommunication Union ITU

Arguably the most successful introduction of CDMA-2000 3G networks is Japan's KDDI, which under the AU brand has more than 20 million 3G subscribers. Since December 2003, KDDI has upgraded the CDMA2000-1x network to CDMA2000-1xEV-DO which achieves data rates up to 2.4 Mbit/s. In 2006, AU plans to upgrade the network to above 3 Mbit/s.

TD-SCDMA
A less well known standard is TD-SCDMA which is being developed in the People's Republic of China by the companies Datang and Siemens. They are predicting an operational system for 2005.

Wideband CDMA
Supports speeds between 384 kbit/s and 2 Mbit/s. When this protocol is used in a WAN, the top speed is 384 kbit/s. When it is used in a LAN, the top speed is 2 Mbit/s. Also adopted by the ITU.

UMTS TDD
Supports speeds of up to 3 Mbit/s.

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The Wikiepedia entry on IMT2000:

IMT-2000 (International Mobile Telecommunications-2000) is the global standard for third generation (3G) wireless communications as defined by the International Telecommunication Union.

In 1999 ITU approved five radio interfaces for IMT-2000 as a part of the ITU-R M.1457 Recommendation. The five standards are:

IMT-2000 CDMA Direct Spread
also known as W-CDMA or UTRA-FDD, used in UMTS
IMT-2000 CDMA Multi-Carrier
also known as CDMA2000, the successor to 2G CDMA (IS-95)
IMT-2000 Time-Code
this summarises UTRA-TDD (standardised in UMTS) and TD-SCDMA
IMT-2000 TDMA Single Carrier
also known as EDGE, an intermediate 2.75G technology
IMT-2000 FDMA/TDMA
also known as DECT