4G (LTE)
Cellular Generations · 8 specs
Direct Answer
4G (Long Term Evolution / LTE-Advanced) is an all-IP cellular architecture standardized under 3GPP Releases 8 through 14. Abandoning CDMA in favor of Orthogonal Frequency-Division Multiple Access (OFDMA), Carrier Aggregation, and 4x4 MIMO, it provides data rates from 150 Mbps (Cat 4) to over 1.2 Gbps (Cat 18 Gigabit LTE) with VoLTE voice.
Source: 3GPP Release 8–14 / ITU-R IMT-Advanced · Last reviewed Aug 28, 2026
Specs
| Standardization Body | 3GPP (Rel-8 LTE to Rel-10/13 LTE-Advanced Pro) / ITU IMT-Advanced |
| Commercial Launch Year | 2009 (TeliaSonera Stockholm/Oslo) |
| Downlink Air Interface | OFDMA (Orthogonal Frequency Division Multiple Access) |
| Uplink Air Interface | SC-FDMA (Single-Carrier FDMA for lower mobile PA power) |
| Scalable Channel Bandwidths | 1.4, 3, 5, 10, 15, and 20 MHz per component carrier |
| Carrier Aggregation (LTE-A) | Up to 5 carriers (100 MHz total aggregated bandwidth) |
| Peak Category Speeds | Cat 4 (150 Mbps), Cat 6 (300 Mbps), Cat 16 (1 Gbps), Cat 18 (1.2 Gbps) |
| Voice Protocol | VoLTE (Voice over LTE / IMS–IP Multimedia Subsystem) |
All-IP Flat Evolved Packet Core (EPC)
4G LTE completely dismantled the legacy circuit-switched telephone network. The Evolved Packet Core (EPC) is a pure, flat IP architecture consisting of the Mobility Management Entity (MME), Serving Gateway (S-GW), and Packet Data Network Gateway (P-GW). Voice calls are carried as high-priority IP packets using Voice over LTE (VoLTE) with AMR-WB (HD Voice) codecs.
OFDMA and Carrier Aggregation
By adopting OFDMA on the downlink, LTE divides 20 MHz channels into 1,200 orthogonal 15 kHz subcarriers. LTE-Advanced (Rel-10) introduced Carrier Aggregation (CA), allowing modems to bond non-contiguous frequency chunks across low, mid, and high bands (e.g. 700 MHz + 1800 MHz + 2600 MHz) with 256-QAM and 4x4 MIMO to exceed Gigabit speeds.