W-CDMA

Wideband-CDMA or W-CDMA is a term used to denote the UMTS radio-interface for the paired bands, UMTS FDD. W-CDMA can be deployed in a number of bands (see UMTS Bands). The core bands for deployment of UMTS FDD Wideband-CDMA are 1920-1980 MHz paired with 2110-2170 MHz. W-CDMA is officially known as IMT-2000 CDMA Direct Spread (CDMA DS). In W-CDMA the bandwidth of the radio channel is 5 MHz. The term is used in contrast to the competitive CDMA system, CDMA2000 and its predecessor cdmaOne, which make use of radio channels of 1.25 MHz width.

The main characteristics of W-CDMA are:

• Wideband Direct Sequence CDMA;
• Frequency Division Duplex;
• Chip rate: 3.84 Mcps,
  can be extended to 8.192 or 16.384 Mcps;
• No need to synchronize the base stations;
• Variable spreading code,
  Spreading factor from 4 to 256;
• Bandwidth between 4.4 and 5 MHz.