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The orthogonal frequency division multiplexed (Orthogonal Frequency Division Multiplexing, OFDM) is a high - speed transmission technology in a wireless environment , mainly through the frequency domain channel is divided into a number of orthogonal subchannels , each subchannel with a sub carrier modulation, each sub-carrier parallel transmission . It has a transmission efficiency of the high - frequency domain equalization technology is simple , effective against frequency selective fading , etc. , can be flexibly combined derivative systems and other access methods , has been widely used in the field of high-speed data transmission . In order to accurately demodulated at the receiving end the transmission signal , the receiving end needs to know the channel state information in order to perform channel equalization on the received signal , the channel estimation is a key technology to realize wireless communication . Broadband wireless OFDM communication channel is a radio channel , which is different from traditional cable channel , different from the general fixed access wireless channel is characterized by strong time , frequency selective fading . In a mobile communication system based on OFDM transmission technology , the time of the channel , frequency selective fading result in different time , the degree of fading of the different sub- carrier transmission signal is not identical . This paper first introduces OFDM system channel estimation techniques Research and development, and then expounded the basic principles of OFDM system , the key technologies of the OFDM system , wireless channel propagation characteristics ; highlights several typical OFDM channel model , pilot insert criteria interpolation algorithm , channel estimation algorithm LS , MMSE , using MATLAB simulation it on this basis , and its simulation results analysis .
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