CDMA2000
(1x)
cdma2000 is a third-generation (3G) wireless technology that is evolved from existing CDMA 2G technology. Its main features are faster data rates, always-on data service, and improved voice network capacity (more people can use each tower at the same time).
See: CDMA
cdma2000 was deployed in several phases.
The first, 1xRTT, supports up to 144 Kbps packet data speeds. It also doubled voice capacity over previous CDMA networks (IS-95).
See: 1xRTT
The next release of 1x, 1xEV-DO Release 0, supports peak data rates up to 2.4 Mbps.
1xEV-DO can only be deployed separately from voice networks - in its own spectrum - although devices can be made to access both networks. Therefore 1xRTT networks must continue to exist side-by-side 1xEV-DO networks, with the former handling voice and the latter handling high-speed data.
An upgrade called 1xEV-DO Revision A increases the maximum download data rate to 3.1 Mbps, among other performance improvements.
See: 1xEV-DO
Another version called 1xEV-DV was originally proposed. It would have fully integrated data and voice, replacing 1xRTT completely. It was abandoned before it was ever deployed.