Research And Simulation On Reference Signal Design And MIMO Technology Of LTE/LTE-Advanced Link Level

In order to meet the requirements on mobile communication technologies within the next decade or longer,3GPP launched the research and standardization of LTE which is long term evolution of 3G system. Owing to the use of some advanced transmission technologies such as OFDM and MIMO, LTE greatly improved the peak data rate and system capacity, and became the main development direction of new mobile communication technologies. Based on LTE,3GPP also launched the enhanced project of LTE called LTE-Advanced (abb.LTE-A), aimed to be a candidate of ITU 4G standards.The topic of this paper comes from the 11th five-year key project-"Development of IMT-Advanced Public simulation evaluation system", 3GPP standardization project, and TD-LTE technology test project. These projects belong to the China Academy of Telecommunication Research of the Ministry of Industry and Information Technology. The main work is to build LTE/LTE-A link level simulation platform according to 3GPP R8, R9 specifications and RIO relevant technical proposals on physical layer and link level layer. Based on the platform, simulation research and evaluation on reference signal design of LTE-Advanced and MIMO technologies of LTE/LTE-Advanced were done, and lots of simulation results were provided to 3GPP for the development and improvement of LTE R9, R10 standards.In this paper, we first outline the LTE/LTE-A system, including the standardization process, the system architecture and the physical layer technologies, and give a brief introduction of theory, platform and tools of link level simulation.Then, we study on reference signal design schemes in LTE-Advanced system, including the density of downlink CSI RS, the intra-cell multiplexing schemes of CSI RS, and the multiplexing schemes of uplink rank 2 DM RS. After the analysis of their principles and characteristics, we give the corresponding proposals according to the simulation results and performance comparison.Finally, we introduce several multi-antenna transmission mode of LTE downlink, study and simulate on transmission diversity, spatial multiplexing and beamforming technologies. Among these, we mainly focus on the scheme of 8 antennas SFBC in LTE-Advanced and the performance of LTE R9 beamforming. According to the simulation results of beamforming, we canculate the corresponding terminal test thresholds used to demodulation.