Research On LTE Downlink MIMO Mode Switch Technology

Mobile multimedia services have the higher and higher bandwidth demands."Mobile Communication Broadband"has become the development trend of mobile communication technologies. The International Standard Organization 3GPP passed the LTE, known as the"3G Long Term Evolution"project work. Multiple Input Multiple Output (Multiple Input Multiple Output, MIMO) as a key technology, can satisfy the needs of the LTE in high data rate and high system capacity. LTE system support the MIMO techniques in PDSCH downward business channel, including spatial multiplexing, beamforming and transmit diversity, etc.It's able to achieve the best requirements of the user average throughput and spectrum efficiency, and improve System transmission rate.It is known that choosing the appropriate MIMO modes in varied situations can achieve better transmission effects. In order to let users reach the better transmission effects, this paper focuses on LTE downlink MIMO mode switch technology system research. Firstly it introduces the downlink physical channel of the TDD LTE system, and studies the generation process of the baseband datadata in TDD LTE downlink physical channel. Secondly it introduces about the MIMO technology in LTE downlink, specific studies the working principle of the seven kinds of the MIMO transmission modes in LTE downlink, theoretically compares the channel capacity of various modes, and proposes the meaning and purpose of researching this topic. Then it builds"TDD LTE downlink control channel PDSCH simulation platform",based on this platform do the MIMO transmission mode simulation experiment, by comparing the simulation results, which are the bit error rate and the throughput of different modes, the switch threshold is determined and an adaptive algorithm of switching MIMO modes is proposed, so get adaptive simulation results. As can be known, the user in the different scene adaptive switch to the appropriate mode can achieve better transmission efficiency.This thesis research content is at the leading edge, mainly through the selection of the switching threshold of MIMO modes to determine the adaptive switching. Actually according to the comprehensive consideration about the channel situation including the bit error rate and the throughput by users feeding back, we select a threshold range. This process has certain error, waiting to research the more accurate method to optimize the threshold choice.