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WCDMA
WCDMA (Wideband Code Division Multiple Access) is a type of 3G cellular network. WCDMA is the technology behind the 3G UMTS standard and is allied with the 2G GSM standard.
More technically, WCDMA is a wideband spread-spectrum 3G mobile telecommunication air interface that utilizes code division multiple access (or CDMA the general multiplexing scheme, not to be confused with CDMA the standard.
History
WCDMA was developed by NTT DoCoMo as the air interface for their 3G network FOMA. Later NTT DoCoMo submitted the specification to the International Telecommunication Union (ITU) as a candidate for the international 3G standard known as IMT-2000. The ITU eventually accepted WCDMA as part of the IMT-2000 family of 3G standards. Later, WCDMA was selected as the air interface for UMTS, the 3G successor to GSM.
Features
Only key features are cited below.
- Supports two basic modes of duplex: FDD (frequency division duplex) and TDD (time division duplex) modes
- Employs coherent detection on uplink and downlink based on the use of pilot symbols
- Inter-cell asynchronous operation
- Variable mission: on a 10 ms frame basis
- Multicode transmission
- Adaptive power control based on SIR
- Multiuser detection and smart antennas can be used to increase capacity and coverage
- Multiple types of handoffs between different cells including soft handoff, softer handoff and hard handoff
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