What is the difference between 1G, 2G, 2.5G, 3G, 4G and 5G (if any)?

Question

Configured to auto mode, an LTE modem will fall back to 3G/2G in bad signal conditions. When it falls back (hands over to 2G or 3G), does it need to make a new PPP dialup connection?

Answer 1

1G = analog

2G = digital, voice
2.5G added data (GPRS)
2.75G faster data (EDGE)

3G = digital, supported data, packet switched (WCDMA, EvDO)
3.5G faster data (HSPA)

4G = wireless broadband
(most people say this is LTE, some people are waiting for an upgrade to LTE-A)

5G = not yet defined
Much faster. Likely to be real ~2020

Answer 2

1G = analog - (NMT, C-Nets, AMPS, TACS) are considered to be the first analog cellular systems, which started early 1980s.

2G = digital, voice - (GSM, cdmaOne, DAMPS) are the first digital cellular systems launched early 1990s.
2.5G added data (GPRS, cdma2000 1x) - (GPRS, cdma2000 1x) are the enhanced versions of 2G networks with data rates up to about 144kbit/s.
2.75G faster data (EDGE)

3G = digital, supported data, packet switched (UMTS FDD and TDD, cdma2000 1x EVDO, cdma2000 3x, TD-SCDMA, Arib WCDMA, EDGE, IMT-2000 DECT, HSPA and HSPA+)

4G = wireless broadband (LTE and WiMax)

5G = not yet defined