In the spring of 2009, 3GPP LTE Release 8 (LTE Rel.8) specification was completed, and it has triggered LTE service deployment by leading mobile network operators. LTE Rel.8 has set various target requirements for LTE, designed to achieve higher system performance than HSPA in 3GPP Release 6. It has improved system capacity, cell edge user throughput and lower C/U-plane latency, supported by introduction of new radio interface technologies, such as OFDM, frequency domain scheduling and MIMO. In the following year, spring of 2010, 3GPP LTE Release 9 (LTE Rel.9) has also been completed to extend various functionalities in LTE Rel.8. The area of enhancement includes closed subscriber group (CSG), self-organizing network (SON), and new functionalities such as location information service and MBMS (Multimedia Broadcast and Multicast Service).
The next important milestone is the standardization of LTE-Advanced (LTE Rel.10 and beyond). To keep up with the today's rapidly growing traffic, especially by the wide spread of smart phone devices, it became necessary to further enhance LTE Rel.9 and achieve much higher level of system performance, while keeping the backward compatibility. Accordingly, the radio access interface specifications for LTE-Advanced has been developed in the beginning of 2011. ITU-T has announced new requirements including spectral efficiency, higher bandwidth, and lower latency. To meet these competitive requirements, a series of new technologies have been discussed to introduce into LTE-Advanced, such as Carrier Aggregation, Enhanced Uplink Multi-antenna Transmission, and CoMP Transmission/Reception. LTE-Advanced will enable 1Gbps downlink bandwidth in addition to the existing LTE service and open a new era of true wireless broadband services in the near future.
LTE-Advanced services will become available from leading mobile network operators around 2014. Additional features include higher downlink bandwidth and non-contiguous spectra usage to further enhance the current LTE services.Evaluation Results against ITU-R Technical Criteria
ITU-R has specified minimum requirements and evaluation criteria for IMT-Advanced in the eight technical areas as listed below.
- Peak spectral efficiency
- Cell spectral efficiency
- Cell edge user spectral efficiency
- Handover interruption time
- VoIP capacity
3GPP TR 36.912 V9.0.0 (2009-09) describes the detailed evaluation results for the ITU-R technical criteria. The 3GPP self-evaluation concluded that LTE Rel.10 & beyond (LTE-Advanced), SRIT (Set of Radio Interface Technology), individual FDD RIT (FDD Radio Interface Technology) and TDD RIT (TDD Radio Interface Technology) components completely satisfied the criteria of the decision step and should move forward to Step 7 of the process. It concluded that, "consequently, the 3GPP LTE Release 10 & beyond (LTE-Advanced) technology should be included in the ITU-R IMT-Advanced terrestrial component radio interface Recommendation(s)."