Research On Algorithm Of Mimo Mode Adaptive Switch In LTE Downlink System

As one of the key technology of LTE system, MIMO could meet the demand of highsystem capacity and high data rate in LTE system. The transmit diversity, spatial multiplexingand beamforming that are include by MIMO technology which supported by the downlinkchannel of PDSCH in LTE system, through which the system could achieve high throughputand high frequency spectrum efficiency ability. Seven different transmission modes which aresupported by the LTE downlink MIMO system, through application different transmissionmode, the system could achieve the best transmission effect in corresponding environment orsituations. In order to make the system to achieve the best effect of the transmission, the LTEdownlink MIMO mode adaptive switch technology is researched in this paper.The characteristics and the key technology in LTE system，the basic theory of MIMOtechnology，seven different transmission mode in LTE downlink MIMO system and the sceneof different mode applied are analyzed, then the TDD LTE downlink PDSCH channelsimulation platform is built based what has been analyzed. Through the platform the channelcapacity and system throughput about transmission diversity, spatial multiplexing andbeamforming are simulated. Through which we got the theory of adaptive switch aboutinternal mode and between modes.According to the CQI information corresponding MCS value that the UE feedback, baseon the theory of making the system achieving the best spectrum efficiency in differentsituations, we got the conditions of mode3internal adaptive switch, mode7internal adaptiveand the adaptive switch between mode3and mode7. Then the LTE downlink MIMO internalmode adaptive switching algorithm based on the test mechanism about mode3and mode7were put forward. At the same time the adaptive switching algorithm about between mode3and mode7is put forwrad also.Through the simulation platform that built in the paper, the system performance ofthroughput about mode3internal and mode7internal adaptive algorithms that base on the test mechanism are separated simulated in different channel correlation. Through analysis thesimulation result we got using the internal mode adaptive switch that base on the testmechanism could achieve the best performance at the transmission mode and the systemthroughput performance could be effectively enhanced. Through the simulation result aboutthe adaptive switch between mode3and mode7, the UE in the different scene adaptiveswitch to the appropriate mode could effectively improve the system throughput performancealso.