IMT-2000

International Mobile Telecommunications for the year 2000 (IMT-2000) is a worldwide set of requirements for a family of standards for the 3^rd generation of mobile communications. The IMT-2000 "umbrella specifications" are developed by the International Telecommunicatons Union (ITU). Originally it was the intention to have only one truly global standard but that turned out to be impossible. IMT-2000 should provide worldwide mobile broadband multimedia services via a single global frequency band. The frequency range should be around 2000 MHz.

In the umbrella specification a number of characteristics are defined which the underying technologies should meet. The main characteristics are:

• Worldwide usage,
  integration of satellite and terrestrial systems to provide global coverage;
• Used for all radio environments,
  (LAN, cordless, cellular, satellite);
• Wide range of telecommunications services,
  (voice, data, multimedia, internet);
• Support both packet-switched (PS) and circuit-switched (CS) data transmission;
• Offer high data rates up to 2 Mbps,
  • 144 kbps for high mobility,
  • 384 kbps with restricted mobility and,
  • 2 Mbps in an indoor office environment;
• Offer high spectrum efficiency;

Family members
For the terrestrial mobile network, there are six family members identified as being IMT-2000 compatible:

• IMT Direct Spread (IMT-DS; also known as UMTS/UTRA-FDD);
• IMT Multicarrier (IMT-MC; also known as CDMA2000);
• IMT Time Code (IMT-TC; also known as UMTS/UTRA-TDD, TD-CDMA and TD-SCDMA “narrowband TDD”);
• IMT Single Carrier (IMT-SC; also known as UWC-136 or EDGE);
• IMT Frequency Time (IMT-FT; also known as DECT).
• IMT OFDMA TDD WMAN (also known as mobile WiMAX)

Originally, the IMT family consisted of five familiy members. The sixth family member (mobile WiMAX) was added later, in october 2007.

Frequency bands
The frequency bands 1885-2025 MHz and 2110-2200 MHz were identified for IMT-2000 by the ITU in 1992. Terrestrial IMT-2000 networks will operate in the following bands:

• 1920 - 1980 MHz paired with 2110 - 2170 MHz,
  FDD with mobile stations transmitting in the lower sub-band.
• 1885 - 1920 MHz and 2010 - 2025 MHz,
  unpaired for TDD operation.

In Europe is the TDD band from 1885-1900 MHz not available for licenses use of IMT-2000, this is used by cordless telephony (DECT).

In addition to this core-band the frequency band 2500 to 2690 MHz was identified in 2000, of which the edges, ranging from 2500-2520 and 2670-2690 MHz, are at first identified for satellite communications. Existing second generation bands (including GSM bands) 806 to 960 MHz, 1429 to 1501 MHz and 1710 to 1885 MHz are also identified for IMT-2000 in the long term.

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