Research On LTE Uplink Adaptive Techniques

3GPP Long Term Evolution (LTE) is the largest research project on new techniques initiated by 3GPP. This LTE technique bases on OFDM/FDMA and it is a revolution in communication industry.The application of adaptive techniques is an important characteristic of the LTE project. The adaptive techniques aim to optimize the configuration of wireless resources.To better study the adaptive techniques, we built a simulation platform of LTE uplink. In physical layer, we simulated the procedures of adaptive modulation and coding (AMC), power control (PC) and resource allocation. We also simulated HARQ procedure in link layer. The cross-layer collaboration in network layer was not included.The simulator mainly referred to the technical reports of 3GPP 25 series. Meanwhile, the contributions to 3GPP conferences by large communication companies were also considered and they provided significant instructions to the simulator design and performance study.After analyzing and studying the simulation results, we obtained profound conclusions on the adaptive techniques.By applying AMC according to link-level simulation results, the parameters for modulation and coding can adapt to the varying channel. In this way, higher spectrum efficiency and better transmission performance can be achieved. HARQ and AMC are complementary to each other. The combination of HARQ and AMC will improve the system performance.Power control procedure has an important effect on system spectrum efficiency. The relationship between spectrum efficiency and SNR targets is an asymptotic function. For certain channel conditions, when the SNR targets achieve a certain value (the trade-off point), the spectrum efficiency can not be improved further and approaches to a limit. And with the application of grouping PC, the system can achieve good spectrum efficiency with low averaged transmitting power.The method of time domain scheduling using a pre-assigned frequency bandwidth pays more attention to the user equipments (UE) with poor channel conditions. It is able to improve the cell edge UEs' data rate. Under same assumptions, spectrum efficiency with proportional fairness (PF) scheduling will be 30% higher than round robin (RR) scheduling.