09 Aug 2016

Overview of WCDMA

Composition of WCDMA Systems
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The 3rd Generation Mobile Communication System (3G) is put on agenda when the 2nd generation (2G) digital mobile communication market is booming.

The 2G mobile communication system has the following disadvantages:

limited frequency spectrum resources, low frequency spectrum utilization, and weak support for mobile multimedia services (providing only speech and low-speed data services).

Also, thanks to incompatibility between 2G systems, the 2G mobile communication system has a low system capacity, hardly meeting the demand for high-speed bandwidth services and impossible for the system to implement global roaming.

Therefore, the 3G communication technology is a natural result in the advancement of the 2G mobile communication.

As the Internet data services become increasingly popular nowadays, the 3G communication technology opens the door to a brand new mobile communication world.

It brings more fun to the people. In addition to clearer voice services, it allows users to conduct multimedia communications with their personal mobile terminals, for example, Internet browsing, multimedia database access, real-time stock quotes query, videophone, mobile e-commerce, interactive games, wireless personal audio player, video transmission, knowledge acquisition, and entertainments.

What more unique are location related services, which allow users to know about their surroundings at anytime anywhere, for example, block map, locations of hotels and super markets, and weather forecast.

The 3G mobile phone is bound to become a good assistant to people’s life and work.

The 3G mobile communication aims at meeting the future demand for mobile user capacity and providing mobile data and multimedia communication services.

Initially, mobile communication technologies were developed separately, as various countries and technical organizations continued to develop their own technologies.

Thus, the USA has AMPS, D-AMPS, IS-136, and IS-95, Japan has PHS, PDC, and the EU has GSM. On one hand, this situation helped to meet the needs of the users at the early stage of mobile communication and expand the mobile communication market.

On another hand, it created barriers between the regions, and made it necessary to unify the mobile communication systems globally.

Under such a context, ITU launched the standardization of the 3G mobile communication system in 1985.

The 3G mobile communication system, IMT-2000, is the general term for the next generation communication system proposed by ITU in 1985, when it was actually referred to as Future Public Land Mobile Telecommunications System (FPLMTS).

In 1996, it was officially renamed to IMT-2000. In addition, the 3G mobile communication technology extends the integrated bandwidth network service as far as it can to the mobile environment, transmitting multimedia information including high quality images at rates up to 10 Mbps.

Compared with the existing 2G system, the 3G system has the following characteristics as summarized below:

  1. Support for multimedia services, especially Internet services
  2. Easy transition and evolution
  3. High frequency spectrum utilization

Currently, the three typical 3G mobile communication technology standards in the world are CDMA 2000, WCDMA and TD-SCDMA.

CDMA 2000 and WCDMA work in the FDD mode, while TD-SCDMA works in the TDD mode, where the uplink and downlink of the system work in different time slots of the same frequency.

The 3G mobile communication is designed to provide diversified and high-quality multimedia services. To achieve these purposes, the wireless transmission technology must meet the following requirements:

  1. High-speed transmission to support multimedia services

               Indoor environment: >2 Mbps

              Outdoor walking environment: 384 Mbps

             Outdoor vehicle moving: 144 kbps

  1. Allocation of transmission rates according to needs
  2. Accommodation to asymmetrical needs on the uplink and downlink

In the concept evaluation of the 3G mobile communication specification proposals, the WCDMA technology is adopted as one of the mainstream 3G technologies

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