2011年4月14日星期四

Outstanding spectrum efficiency

For the TD-SCDMA system, every carrier only needs bandwidth of 1.6 MHz. Very rich spectrum resources are available. Nine frequency points are available in the globally unified 2010~2025 MHz TDD core bands, with an additional 24 frequency points available in the 1880~1920 MHz band. Globally, nearly all countries have reserved some bands for TDD.

Apart from rich frequency resources, TD-SCDMA features the highest spectrum utilization, which is closely related to the unique advanced technologies of TD-SCDMA. Its high spectrum utilization is reflected in the following aspects:

  • Using TDD technology, uplink and downlink transmissions are in the same frequency. In this way, no frequency pair is needed, and dispersed spectrum can be better used, offering a good solution to frequency resource shortages.
  • With the TDD technology used, every radio frame has uplink/downlink timeslot switch points to flexibly adjust the uplink/downlink timeslots into symmetric or asymmetric distribution, helping to meet the requirements for transmitting symmetric voice service and asymmetric data service. This is most suitable for the networking requirements of 3G networks that provide asymmetric data services as a special feature.
  • Although TD-SCDMA is also a CDMA system, it uses multiple advanced technologies to effectively reduce interference, for example smart antennas, joint detection, multiple cell joint detection, uplink synchronization, and N-frequency technology. These help to alleviate the system breathing effect and make it possible for co-frequency networking and full code channel working. With the same frequency resources, TD-SCDMA can support more users and provide higher transmission bandwidth

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