LTE stands for Long Term Evolution. In order to understand why it's necessary, let's look at the evolution of mobile technologies, from the first generation (1G) to the fourth generation (4G).
The data speed set for 4G standard by ITU Radiocommunication Sector(ITU-R) is rather unreachable despite the amount of money manufacturers invested to achieve it. To get around this problem, 3GPP introduced LTE, which refers to the technology that is used in pursuit of 4G standard — the technology could be labeled 4G if it provides a substantial improvement over 3G. 4G LTE is a marketing term that allows service providers to claim next generation connectivity without having to achieve the 4G standard requirement.
| Technology | 1G | 2G | 2.5G | 3G | 4G |
| Design began | 1970 | 1980 | 1985 | 1990 | 2000 |
| Implementation | 1981 | 1991 | 1999 | 2001 | 2010 |
| Services | Analog voice | Digital voice, short message | Higher capacity, packetized data | Higher capacity data rates up to 2 Mbps | Higher capacity, completely IP-oriented, multimedia, data to hundreds of megabits |
| Access Technology | AMPS, TACS, NMT | TDMA, CDMA GSM | GPRS, EDGE | WCDMA, CDMA2000 | One standard |
| Data rate | 1.90 kbps | 14.4 kbps | 384 kbps | 2 Mbps | > 200 Mbps |
| Multiplexing | FDMA | TDMA, CDMA | TDMA, CDMA | CDMA | OFDM |
| Core Network | PSTN | PSTN | PSTN, packet network | Packet network | Internet |
| Architecture | Circuit switch | Pacet switch | Circuit switch, packet switch | Packet switch |
The inability to achieve 4G capacity is due to the lack of carrier aggregation and because phones do not have multiple antennae. Multiple Input Multiple Output (MIMO) is a technique for sending and receiving more than one data signal on the same channel at the same time by using more than one antenna. Combining carrier aggregation and MIMO brings us to LTE Advanced (LTE-A).
LTE supports scalable bandwidths of up to 20 MHz and provides peak data rates of 300 Mbps downlink and 75 Mbps uplink. LTE is also designed for reduced service latency, optimized packet transmission and simplified implementation complexity for cost reduction. LTE-A supports bandwidth of up to 100 MHz and provides peak data rate 3 Gbps downlink and 1.5 Gbps uplink.
