cellular generations
The evolution of cellular communication systems is commonly known by 1G, 2G and 3G designations. We are currently in the third generation (3G). See also wireless LAN, wireless glossary and cellular vs. Wi-Fi.
1G - Analog
Introduced in the late 1970s and early 1980s, the first cellular systems were analog. They were used for data just like land-based telephone lines are used for dial-up with analog modems. A handful of cellphone models could be adapted to laptop modems and transfer data at less than 15 Kbps while traveling. See AMPS, TACS and NMT.
2G - 2.5G - Digital
The second generation refers to digital voice cellphone systems deployed in the 1990s, which were based on GSM, TDMA or CDMA. Several so-called 2.5G (or 2G+) technologies added data services for Internet access and e-mail with typical downstream speeds ranging from 64 to 200 Kbps for the user. See GPRS, EDGE and IS-95.
3G - High Speed
Launched after the turn of the century, the third generation offers faster access to the Internet and other data services with typical downstream speeds ranging from 400 Kbps up to several megabits per second for the user. See EV-DO, WCDMA and HSPA.
Defined by the ITU under the IMT-2000 framework, 3G is implemented regionally in Europe (UMTS), North America (CDMA2000 and UMTS) and Japan (NTT DoCoMo). 3G also embraces worldwide roaming for global travelers (see GAN). See UMTS, CDMA2000, NTT DoCoMo and 3GPP.
4G - Higher Speed for Movies and TV
In the 2010-2015 time frame, the LTE technology for GSM phones and UMB technology for CDMA phones are expected to support TV in real time as well as video downloads at high speed. They are also expected to embrace automatic roaming to non-cellular systems such as Wi-Fi, satellite and other wireless networks, whichever is most appropriate. See HSPA and 3GPP.
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