WCDMA (wideband code division multiple access)
UMTS standard for 3G digital mobile networks, using CDMA technology. It is the evolution path for GSM and EDGE to UMTS and offers increased voice capacity and theoretical peak data speeds of up to 2 Mbps. The 3GPP task group continues to work on the evolution of WCDMA toward 4G and has defined a series of evolutionary steps:
R.99 (Release 99) — Specifications (completed in 1999) for the original version of WCDMA, a 3GPP standards project to define the requirements and basic framework for UMTS 3G mobile networks. R.99 defined the UTRA and the basic features of this early 3G development.
R.4 (Release 4) — Specifications (released in 2004) for the next evolution beyond R99. R4 was the first step toward an all-IP core network, adding separation of the control channel from the connection in the circuit-switched core network, and basic VoIP routing.
R.5 (Release 5) — Specifications (released in 2005) for the next evolution beyond R4. R.5 extends WCDMA to include HSDPA and HSUPA for high-speed packet data services and IMS for multimedia and converged IP network support. It added IP transport in the UTRAN.
R.6 (Release 6) — Specifications (completed in 2006) for the next evolution beyond R5. R.6 extends WCDMA to include MBMS for mobile TV services, PoC and EUDCH for enhanced uplink speeds and system capacity. R.6 adds IMS Phase 2 and UMTS/WLAN interworking.
R.7 (Release 7) — Also known as LTE, the specifications (frozen at the end of 2007) for the next evolution beyond R.6. It will add radio enhancements, MIMO, end-to-end IP telephony and evolved EDGE.
R.8 (Release 8) — Further extension of LTE and SAE capabilities prior to the advent of 4G. R.8 is likely to add OFDMA for the downlink and SC-FDMA for the uplink in the UTRAN. R8 specifications were frozen in December 2008.
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