Long Term Evolution (LTE) of the 3GPPTM radio technology
The basic criteria for the work on LTE were:
- Demand for higher data rates
- Expectations of additional 3G spectrum allocations
- Greater flexibility in frequency allocations
- Continued cost reduction
- Keeping up with other technologies.
More specifically:
- Significantly increased peak data rates
- Increased bitrates at the edge of cells
- Improved spectrum efficiency
- Improved latency
- Scaleable bandwidth
- Reduced capital and operational expenditure
Acceptable system and terminal complexity, cost and power consumption
Compatibility with earlier releases and with other systems
Optimized for low mobile speed but supporting high mobile speed (up to 500 km/h).
3GPPTM Technical Report TR 25.913 collects together all the agreed requirements for the Evolved UTRA & UTRAN.
In response to these requirements, various radio technologies were considered but the conclusion was that the downlink would use Orthogonal Frequency Division Multiplexing (OFDM) and the uplink would use Single Carrier - Frequency Division Multiple Access (SC-FDMA). Supported downlink data-modulation schemes are QPSK, 16QAM, and 64QAM, whilst the possible uplink data-modulation schemes are BPSK, QPSK, 8PSK and 16QAM.
3GPPTM Technical Report TR 25.814 defines the physical layer aspects of Evolved UTRA.
System Architecture Evolution (SAE)
The objectives of the complementary SAE study were:
'to develop a framework for an evolution or migration of the 3GPPTM system to a higher-data-rate, lower-latency, packet-optimized system that supports multiple Radio Access Technologies.
The focus of this work is on the PS domain with the assumption that voice services are supported in this domain'.
The particular focus has been on:
The possible use of various access technologies (wireless and wired) has been assumed - not just Enhanced UTRA.
The report of the SAE study can be found in 3GPPTM Technical Report TR 23.882.