Evolution of mobile communication up to 3G

Mobile communication developed from early manual radio telephone systems to automatic cellular networks, and then through generations that added digital voice and finally mobile data.

Early development (pre-cellular)

• 1946: first public mobile telephone service in the USA (Mobile Telephone Service), single high-power transmitter, few channels, push-to-talk.
• 1960s: IMTS (Improved Mobile Telephone Service) – automatic dialling, full duplex, but still very limited capacity.
• 1970s: Bell Labs developed the cellular concept – small cells, low-power transmitters and frequency reuse – which solved the capacity problem.

First generation (1G) – analog cellular (1980s)

• Analog FM voice, FDMA, circuit switched.
• Systems: AMPS (USA, 1983), NMT (Nordic), TACS (UK), NTT (Japan).
• Problems: poor security (easy to eavesdrop), low capacity, no data, incompatible standards.

Second generation (2G) – digital (1990s)

• Digital modulation and speech coding, TDMA or CDMA, encryption, SMS.
• Systems: GSM (Europe, TDMA, 200 kHz), IS-136 (USA Digital AMPS), IS-95 cdmaOne (CDMA, 1.25 MHz), PDC (Japan).

2.5G – data on 2G networks

• HSCSD (circuit-switched multiple slots), GPRS (packet switched, up to ~171 kbps), EDGE (8-PSK, up to ~384 kbps), IS-95B.

Third generation (3G) – IMT-2000 (2000s)

• Wideband CDMA, 5 MHz carriers, up to 2 Mbps; video calls, internet, global roaming.
• Systems: UMTS/W-CDMA (3GPP), CDMA2000 (3GPP2), TD-SCDMA (China). Later HSPA (3.5G).

         GSM → GPRS → EDGE ─┐
 1G  →   IS-136 ────────────┼→ W-CDMA/UMTS → HSPA
(AMPS)   PDC ───────────────┘
         IS-95 → IS-95B ──────→ CDMA2000 1x → EV-DO
  1G        2G       2.5G           3G