Research On The Technology Of Channel Estimation In MIMO-OFDM System

With the continuous development of communication systems,the original single-antenna transmission systems has not been able to meet the needs of telecommunication transmission,we must break through the existing transmission bottlenecks,improve the level of system transmission.The technology of MIMO meets people's requirements of improve transmission performance,multi-antenna transmission can improve overall system capacity at the same bandwidth circumstance.Combined this technology with OFDM compose the MIMO-OFDM system can be the mainly technology used in next-generation communication,which can meet people at the communication needs at this stage.This thesis is to conduct the studies in such a background.Channel estimation is the focus of the study for MIMO-OFDM system;this thesis does the study from many aspects of channel estimation.First of all it introduces the MIMO-OFDM system,analyses the principle of their composition of MIMO and OFDM,the technical characteristics and advantages and disadvantages.It can be better to transmit data in this system of combined this two technologies together.It introduces a wireless communications environment,analyzes them and comes to different conclusions in the actual situation of variety of environments with MIMO-OFDM system.Analyzed the system and introduced the traditional methods of channel estimation,formulas are derived,and simulated the Least Squares(LS) method in channel estimation that can reduce the BER of the system.Compared the method of Minimum Mean Square Error(MMSE) and its improved algorithm of channel estimation,which can be verified the performance of improved algorithm is improved.Analyzed the system intensively to study the synchronization method of the channel estimation,studied the importance of synchronization in channel estimation, and verified the feasibility of an algorithm in the synchronize of the system.Pilot is the essential step to study the channel estimation,introduced the principle of pilot-based of estimation,and analyzed the different pilots play a role in the system. In this thesis,on the basis of previous studies,combined with original research results, re-analyze of the best training sequence and interpolation filter methods,combined several methods and then carry out the comparison,and educed the simulation results to verify its presence which can reduce the BER in channel estimation and improve system performance.For the subsequent further study of the system must provide a theoretical basis.