Research On Pilot-aided Channel Estimation Of OFDM Systems

OFDM(Orthogonal Frequency Division Multiplexing) is a kind of multi-carriermodulation (MCM) technology. It has a lot of advantages which are strong anti-multipathfading, anti-ISI, anti-narrowband interference and high frequency efficiency, etc., and it bythe people’s attention. However, in order to make the OFDM system to transfer informationbetter，there are number of key technologies to be solved,such as channel estimationtechniques.The channel estimation techniques is based on the coherent demodulationmode.We all know that coherent demodulation need to use the channel information,so wemust estimation and track the characteristics in real time to obtain t channel stateinformation timely at the receiving end.Channel estimation can be defined the qualitative research process to describe thephysical channel of the input signal.In other words,it is estimated that the frequencyresponse of the wireless channel between the transmitting antenna to receiving antenna.InOFDM system,channel estimation is the key technology to ensuring the correctdemodulation of the signal.Firstly,the study gives a detailed description on the propagation characterristics ofwireless channel and the basic principles of the OFDM system,then, it lesds to the conceptof channel estimation,and explain the importance of the principle of the channel estimation,otherwise it gives the methods of the channel estimation.the study focus on the one of themost important methods__the channel estimation method based on the pilot study.Thismethod is estimated from two aspects:the method of channel estimatation based on pilotand the method of channel estimatation based on data,then compare and analysis theadvantages and disadvantages of these algorithms.Then,in order to improve the systemcapcity,the study gives a method called hidden-pilot based on these algorithms,which caneffectively save the system bandwidth.Finally,we gives the result of the computersimulation of these algorithms.