International Mobile Telecommunications-2000 (IMT-2000) is a global set of standards developed by the International Telecommunication Union (ITU) for the third generation (3G) of mobile communications systems. IMT-2000 serves as an umbrella specification for a family of standards that enable worldwide mobile broadband multimedia services. These standards are designed to provide high-quality voice, data, multimedia, and internet services to mobile users across the globe.

Key characteristics and goals of IMT-2000 include:

1. Worldwide Usage: IMT-2000 standards aim to provide global coverage, allowing users to access services seamlessly across different regions and countries.
2. Integration of Satellite and Terrestrial Systems: IMT-2000 envisions the integration of satellite and terrestrial communication systems to ensure comprehensive global coverage.
3. Support for Various Radio Environments: IMT-2000 standards are adaptable to different radio environments, including local area networks (LANs), cordless systems, cellular networks, and satellite communications.
4. Wide Range of Telecommunications Services: IMT-2000 is designed to support a wide array of telecommunications services, including voice calls, data transmission, multimedia streaming, and internet access.
5. Packet-Switched and Circuit-Switched Data: IMT-2000 standards support both packet-switched (PS) and circuit-switched (CS) data transmission, enabling efficient data communication.
6. High Data Rates: IMT-2000 standards offer high data rates, with up to 2 Mbps (megabits per second) achievable. Data rates can vary based on mobility and environment, ranging from 144 kbps for high mobility to 2 Mbps in an indoor office environment.
7. High Spectrum Efficiency: IMT-2000 standards are designed for efficient use of the radio spectrum, ensuring optimal utilization of available resources.

The IMT-2000 family includes various terrestrial mobile network technologies, each with its own set of specifications and characteristics. Some of the key IMT-2000 family members include:

• IMT Direct Spread (IMT-DS): Also known as UMTS/UTRA-FDD, this technology uses Direct Sequence Spread Spectrum for wide-area coverage.
• IMT Multicarrier (IMT-MC): Also known as CDMA2000, this technology utilizes Code Division Multiple Access (CDMA) with multiple carriers for high-capacity networks.
• IMT Time Code (IMT-TC): This technology, including UMTS/UTRA-TDD, TD-CDMA, and TD-SCDMA, is optimized for time-division duplexing (TDD) and narrowband TDD operation.
• IMT Single Carrier (IMT-SC): Also known as UWC-136 or EDGE, this technology uses a single carrier for data transmission.
• IMT Frequency Time (IMT-FT): Known as DECT (Digital Enhanced Cordless Telecommunications), this technology offers reliable wireless communication.
• IMT OFDMA TDD WMAN: This includes mobile WiMAX, which is based on Orthogonal Frequency Division Multiple Access (OFDMA) and is designed for wireless metropolitan area networks (WMANs).

IMT-2000 specifies frequency bands for terrestrial networks, including paired and unpaired frequency allocations. It encompasses various frequency bands to accommodate different technologies and applications.

Overall, IMT-2000 plays a crucial role in shaping the global landscape of mobile communication by providing standards that support advanced multimedia services and international roaming capabilities.