- Asked 6/22
- 2080 Baisakh · 4 marks
- 2077 Chaitra · 5 marks
3G versus 4G mobile communication
Short answer
3G uses wideband CDMA with fixed 5 MHz carriers and circuit plus packet core, while 4G uses OFDMA/SC-FDMA with scalable bandwidth, MIMO and all-IP core. 4G gives up to 100 Mbps mobile and 1 Gbps fixed, lower latency about 10 ms, and VoLTE instead of circuit voice.
Compare and contrast third and fourth generation of mobile communication standards in terms of technology advancement.
3G (IMT-2000) introduced mobile data and multimedia using wideband CDMA, while 4G (IMT-Advanced) provides high-speed all-IP broadband using OFDMA and MIMO.
| Feature | 3G | 4G |
|---|---|---|
| ITU family | IMT-2000 | IMT-Advanced |
| Standards | UMTS/W-CDMA, CDMA2000, TD-SCDMA, HSPA | LTE-Advanced, WiMAX 2 (802.16m) |
| Multiple access | Wideband CDMA | OFDMA downlink, SC-FDMA uplink (LTE) |
| Bandwidth | 5 MHz (fixed) | Scalable 1.4–20 MHz, carrier aggregation up to 100 MHz |
| Peak data rate | 384 kbps–2 Mbps (HSPA+ up to 42 Mbps) | 100 Mbps mobile, 1 Gbps stationary |
| Core network | Circuit (voice) + packet (data) | All-IP packet core (EPC) |
| Voice | Circuit-switched | VoIP (VoLTE) |
| Latency | ~100 ms | ~10 ms |
| Antenna | Mainly single antenna | MIMO (2×2 to 8×8) |
| Modulation | QPSK, 16-QAM | QPSK, 16/64/256-QAM, adaptive |
| Handoff | Soft handoff | Hard handoff |
| Spectral efficiency | Low | High (several bit/s/Hz) |
Main technology advancements in 4G
- OFDM splits the wide channel into many narrow orthogonal subcarriers, so each sees flat fading; a cyclic prefix removes ISI, avoiding complex equalisers.
- MIMO gives spatial multiplexing (higher rate) and diversity (reliability).
- Flat architecture – the eNodeB includes radio control functions previously done by the RNC, reducing latency.
- Link adaptation and fast scheduling (adaptive modulation and coding, HARQ).
- Carrier aggregation and support for both FDD and TDD.
✓ Answer checked by Claude Opus 5.5 (high effort)
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