Long Term Evolution

The 3GPP^TM radio interface, UTRA (Universal Terrestrial Radio Access), with the enhancements provided by High Speed Packet Access (HSPA), for both downlink and uplink, will remain highly competitive for several years. Nevertheless, the industry that has developed the 3GPP^TM technologies is anxious to ensure the continued competitiveness of those technologies and has launched a Long Term Evolution project within 3GPP.

The focus of the LTE project is on:

• enhancement of the Universal Terrestrial Radio Access (UTRA)
• optimization of the UTRAN architecture.

A parallel activity is taking place on the evolution of the 3GPP^TM System Architecture (SAE).

A more complete summary of the LTE and SAE programmes can be found on the 3GPP^TM website.

Long Term Evolution (LTE) of the 3GPP^TM 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).

3GPP^TM 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.

3GPP^TM 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 3GPP^TM 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:

• enhancement of Packet Switched technology to cope with rapid growth in IP traffic, i.e.

  • higher data rates
  • lower latency
  • packet-optimized system
• through
  • fully IP network
  • simplified network architecture
  • distributed control.

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 3GPP^TM Technical Report TR 23.882.