中文说明：这并没有噪声对OFDM编码
English Description：
this mathlab code about OFDM without noise Time-varying channel estimation is an important activity in next generation wireless communication. Channel estimation is required mainly for the significant signal processing operation in multiple input multiple output (MIMO)-orthogonal frequency division multiplexing (OFDM) systems such as precoder designing at transmitter & relay and relay selection scheme in cooperative communication system. In this paper we investigate and compare various efficient channel estimation schemes for OFDM system. In this paper the channel estimation techniques based on block type Pilot arrangement for OFDM system are investigated. Finally, the discrete Fourier transform (DFT) based channel estimation technique is performed which gives better performance over least square(LS) and minimum mean square error(MMSE) based channel estimation. The bit error rate (BER) of DFT based channel estimation is less than the BER of LS and MMSE based chan