IMT-2000: The Rise of 3G - 1.3

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IMT-2000 laid down a comprehensive set of objectives and technical requirements that 3G systems needed to meet. Foremost among these was the demand for **significantly higher data rates** than 2G or 2.5G. While earlier generations focused on voice, 3G aimed to deliver speeds of at least 144 kilobits per second for mobile users, 384 kilobits per second for pedestrians, and a powerful 2 megabits per second for stationary or low-mobility environments like offices. This substantial increase in bandwidth was crucial for the next major goal: **supporting rich multimedia services**. This meant enabling capabilities like real-time video calling, fluid mobile internet Browse, streaming of audio and video content, and rapid transmission of large email attachments.

Another critical objective was **global roaming and interoperability**. The ITU envisioned a world where a single mobile device could seamlessly operate across different countries and networks, fostering a truly global mobile communication environment. This required a harmonized set of standards.

Under the IMT-2000 umbrella, several radio interface technologies were standardized. The two most prominent terrestrial families that emerged were:

1.  **WCDMA (Wideband Code Division Multiple Access):** This technology became the foundation for **UMTS (Universal Mobile Telecommunications System)**, the 3G standard adopted primarily by operators who had evolved from GSM networks. WCDMA utilized a wide 5 MHz radio channel and sophisticated Code Division Multiple Access techniques to allow many users to share the same spectrum, leading to high capacity and efficiency.
2.  **cdma2000:** This was the evolutionary path for operators who had deployed 2G cdmaOne (IS-95) networks, primarily in North America and parts of Asia. It built upon the existing CDMA technology, with versions like cdma2000 1xEV-DO delivering robust high-speed packet data.
    A third standard, **TD-SCDMA**, was also developed in China to meet its specific market needs, using a combination of time and code division multiplexing.

The first commercial 3G networks based on these IMT-2000 standards began rolling out in the early 2000s, initially in Japan and South Korea. The rise of 3G fundamentally changed the mobile landscape. It transformed mobile phones from voice-and-text devices into truly multimedia-capable internet terminals, paving the way for the smartphone era and setting the stage for even faster mobile broadband technologies like 4G.

Key Concepts

• ITU's Role: How IMT-2000 standardized 3G globally.

• Data Rate Targets: The specific speed improvements over 2G/2.5G.

• Shift to Multimedia: The new services enabled.

• WCDMA & cdma2000: The two dominant 3G technology families.

• Packet-Centric Network: The fundamental architectural change.

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• Examples

• Before 3G: Watching a video on a mobile phone was generally not feasible; you'd download it slowly, if at all, or watch pixelated, constantly buffering clips.

• With 3G (IMT-2000 compliant): Users could engage in real-time video calls, experience significantly faster web Browse, and stream music directly to their phones with much less buffering.

• Global Roaming Example: An executive traveling from a GSM-based country to a cdma2000-based country could ideally use the same 3G handset and number, thanks to the harmonized IMT-2000 standards.

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• Flashcards

• Term: IMT-2000

• Definition: ITU standard for 3G, defining requirements for high-speed multimedia mobile communication.

• Term: 3G

• Definition: Third generation of mobile tech, focused on higher data rates, multimedia, and packet-switching.

• Term: WCDMA (UMTS)

• Definition: Primary 3G radio interface derived from GSM, using wideband CDMA.

• Term: cdma2000

• Definition: 3G standard evolved from 2G cdmaOne.

• Term: 2 Mbps (3G target)

• Definition: Target data rate for stationary/low-mobility users in IMT-2000 systems.

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• Memory Aids

• IMT-2000: "I Must Transmit - 2000 kilobits per second\!" (Helps remember the speed target and the year focus).

• 3G: "Global GPRS Guts\!" (Highlights the global nature, the GPRS evolution, and the fundamental architectural change).

• "WCDMA for World, cdma2000 for C (CDMA) countries." (Helps distinguish the two main standards).

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