Research On Multi-user MIMO Grouping Strategy In LTE-Advanced System

MIMO refers to a communication system that uses multiple antennas to transmit and receive simultaneously and significantly improve system capacity and spectrum utilization without increasing the system bandwidth.In recent years,radio spectrum resources became more scarce and precious,the focus point of MIMO gradually shifts from SU-MIMO to MU-MIMO.In MU-MIMO systems,the MU-MIMO aggregate capacity depends on the channel correlation of the UEs within the same group.The channel vectors of different users are usually correlated,and this correlation will seriously degrade the performance of the MIMO system.Therefore,it is crucial to carry out multi-user grouping for the performance of MU-MIMO system.This paper first introduces the key technologies of LTE/LTE-A system and MU-MIMO principle.Then we study the multi-user grouping algorithms in the two scenarios in the downlink of LTE/LTE-A system respectively,one is the base station can obtain the user's complete channel state information,the other is the limited pilot resource scenario.In the third chapter,we propose a multi-user grouping algorithm based on hierarchical clustering which can adjust the number of group by controlling the cutoff value of the merging between groups,and then achieve the purpose of improving system performance.In the fourth chapter,we propose a grouping algorithm that uses CRS aided information to ensure user channel accuracy,and build a LTE/LTE-A system-level simulation platform to verify the proposed algorithm.The simulation results show that the proposed algorithm improves the overall performance of the system.