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There are many different types of CDMA2000. In order of increasing complexity:
CDMA2000 1x, also known as CDMA2000 1xMC (Multi-Carrier), is the core 3G CDMA2000 technology. The designation Multi-Carrier refers to the possibility of using up to three separate 1.25 MHz carriers for data transmission, and is used to distinguish this from W-CDMA, which is a direct spread protocol using a wide 5 MHz carrier. However, as the 1x protocol only uses a single carrier, the term 1xMC is slightly oxymoronic and the simpler term CDMA2000 1x is recommended instead.
Confusingly, Japanese operator KDDI uses the brand "CDMA 1X WIN" for their CDMA2000 1xEV-DO network.
CDMA2000 1xRTT (Radio Transmission Technology) is the basic layer of CDMA2000, which supports up to 144 kbit/s packet data speeds. While 1xRTT officially qualifies as 3G technology, 1xRTT is considered by most to be a 2.5G technology as it is several times slower than other 3G technologies. It also doubles voice capacity over previous CDMA networks.
CDMA2000 1xEV (Evolution) is CDMA2000 1x with High Data Rate (HDR) capability added. 1xEV is commonly separated into two phases:
Phase 1 of CDMA2000 1xEV, CDMA2000 1xEV-DO (Evolution-Data Only) supports downlink (Forward Link) data rates up to 3.1 Mbit/s and Up Link (Reverse Link) rates of 154kbps.
Phase 2 of CDMA2000 1xEV, CDMA2000 1xEV-DV (Evolution-Data and Voice), supports downlink (Forward Link) data rates up to 3.1 Mbit/s and Up Link (Reverse Link) rates of up to 451 kbits/s. 1xEV-DV can also support legacy 1x voice and data users -- though not while operating at 3.1 Mbit/s.
1xEV-DO is commercially deployed around the world. In January 2004, Verizon Wireless in North America announced its intention to deploy 1xEV-DO nationally.As of July 2004, there are no commercial deployments of 1xEV-DV, although some carriers are carrying out testing and limited trials. American carrier Sprint PCS has announced plans to deploy a 1xEV-DV network on top of their existing CDMA network. However, due to delays in the availability of 1xEV-DV equipment and competitive pressures from other American networks deploying 3G networks, Sprint announced, in June 2004, its intention to broadly deploy 1xEV-DO. Sprint's longterm 1xEV-DV plans seem uncertain.
CDMA2000 3x uses three separate 1.25 MHz carriers. This provides three times the capacity but also requires three times more bandwidth, and remains under development.
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