3G, or third generation mobile telephony technology, as the name suggests follows two earlier generations.

First generation cellphones came into use in the early '80s with commercial deployment of Advanced Mobile Phone Service (AMPS) cellular networks. Early AMPS networks used Frequency Division Multiplexing Access (FDMA) to carry analog voice over channels in the 800 MHz frequency band.

Second generation technology emerged in the '90s when mobile operators deployed two competing digital voice standards. Across the world, many operators adopted the Global System for Mobile communication (GSM) standard, which used Time Division Multiple Access (TDMA) to multiplex up to 8 calls per channel in the 900 and 1800 MHz bands.

The International Telecommunications Union (ITU) then defined third generation mobile telephony standards - IMT-2000 - to facilitate growth, increase bandwidth, and support more diverse applications.

While GSM could carry voice and circuit-switched data at speeds up to 14.4 kbps, 3G had to deliver packet-switched data with better spectral efficiency at far greater speeds to accommodate mobile multimedia applications.

To get from 2G to 3G, mobile operators had make "evolutionary" upgrades to existing networks while simultaneously planning their "revolutionary" new mobile broadband networks.

ResearchTelecom.com

(China Daily 06/08/2009 page7)