3G glossary

Confused by all the technical jargon and acronyms surrounding 3G? We don't blame you. Here's a quick guide to the terms you'll need to know.

1xEV-DO: Also known as Evolution, Data-Only, this subset of CDMA2000 runs on CDMA networks and reaches peak speeds of 2.4Mbps and averages 300Kbps to 600Kbps. As its name implies, EV-DO networks handle only high-speed data; handsets supporting EV-DO would use the underlying CDMA network for voice calls. Both Verizon and Sprint are launching 1xEV-DO service.

1xEV-DV: Also known as Evolution, Data-Voice, 1xEV-DV is the next step in CDMA2000 technology after 1xEV-DO, handling both data and voice calls at speeds up to 2.4Mbps.

1xRTT: A subset of CDMA2000 that runs on CDMA networks, 1xRTT (or Radio Transmission Technology) offers speeds of up to 144Kbps, although users will typically get speeds between 60Kbps and 80Kbps. While 1XRTT is sometimes referred to as 3G technology, it falls a bit short in terms of speed and actually is 2.5G. Both Sprint and Verizon support 1xRTT.

AMPS: Advanced Mobile Phone Service, the first-generation, analog cellular network that arrived in the United States in the 1980s. While digital networks have taken over most populated areas in the United States, AMPS still covers rural areas that CDMA and GSM can't reach.

CDMA: Code-Division Multiple Access, a 2G digital cellular network first launched in 1995 and--until a recent surge by 2G competitor GSM--the unchallenged leader in stateside cell service. Wireless carriers Verizon and Sprint both use CDMA.

CDMA2000: The next step in CDMA technology, CDMA2000 comprises 1xRTT (2.5G), 1xEV-DO, and 1xEV-DV (both 3G).

EDGE: Enhanced Data rates for GSM Evolution (or Enhanced Data GSM Environment), a 2.5G enhancement for GSM with a theoretical top speed of 200Kbps, although real-world speeds will be closer to 90Kbps.

GPRS: An upgrade for GSM networks, General Packet Radio Service is a 2.5G technology that bumps data speeds up to 50Kbps, although real-world speeds are closer to 30Kbps and 40Kbps.

GSM: Global System for Mobile Communications. This 2G (about 9.6Kbps) digital network is most pervasive in international markets, although it's made significant headway in the United States.

HSDPA: An enhancement for 3G UMTS networks, High Speed Downlink Packet Access promises bone-rattling speeds of up to 14.4Mbps, compared to a "mere" top speed of 2Mbps for UMTS.

iDEN: A 2G network primarily used for business. Nextel was the first cellular network with PTT functionality but it now is offered by others.

PTT: Push to talk, a two-way mobile technology that works like a walkie-talkie and is not the same as placing a normal voice call.

TDMA: Time Division Multiple Access, the original digital technology on which GSM is based.

UMTS: Universal Mobile Telephone Service, the 3G service that GSM carriers AT&T and T-Mobile plan to roll out for its subscribers. UMTS boasts speeds of up to 2Mbps, although users will typically see speeds in the 300Kbps-to-400Kbps range.

WiMax: A high-performance version of Wi-Fi, WiMax (or 802.16) networks would offer the bandwidth of Wi-Fi at ranges measured in miles rather than feet. Many industry observers feel that WiMax could be the cornerstone of 4G wireless networks, boasting speeds rivaling those of wired gigabit Ethernet networks.

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