Evolution of generations of cellular systems

Cellular systems have evolved roughly every ten years, each generation adding new services and better spectrum efficiency.

1G (1980s) – analog voice

• Analog FM, FDMA, 30 kHz channels, circuit switching.
• AMPS, NMT, TACS. Voice only, poor security, low capacity, no roaming between standards.

2G (1990s) – digital voice

• Digital modulation (GMSK, QPSK), speech coding, TDMA and CDMA, encryption, SIM.
• GSM, IS-136, IS-95. Services: voice, SMS, 9.6–14.4 kbps data.
• 2.5G: GPRS and EDGE add packet data (up to ~384 kbps), enabling WAP, MMS, e-mail.

3G (2000s) – mobile data and multimedia

• IMT-2000 family: UMTS/W-CDMA, CDMA2000, TD-SCDMA; 5 MHz carriers; up to 2 Mbps.
• Video calls, mobile internet, global roaming; soft handoff.
• 3.5G/3.75G: HSPA, HSPA+, EV-DO (up to tens of Mbps).

4G (2010s) – all-IP mobile broadband

• LTE-Advanced, WiMAX (IMT-Advanced): OFDMA, MIMO, carrier aggregation.
• Peak rates 100 Mbps (high mobility) to 1 Gbps (low mobility), latency ~10 ms, voice over IP (VoLTE), HD video streaming.

5G (2020s) – IMT-2020

• New Radio (NR), mmWave and sub-6 GHz bands, massive MIMO, beamforming, network slicing.
• Peak 20 Gbps, latency ~1 ms, up to 10⁶ devices/km².
• Use cases: eMBB, URLLC (self-driving, remote surgery), mMTC (IoT).