OFDM Modem N subchannels Ncomplex samples quadrature Bits I amplitude add D/A+ 十 S/P modulation ● W-IFFT ● ● cyclic ● P/S transmit 001101 ● QAM) ● prefix ● filter encoder TRANSMITTER RECEIVE multipath channel R Ncomplex N subchannels samples nvert channel Receive remove QAM ● filter decoder ● ● W-FFT ● S/P cyclic + ● ● frequency ● ● prefix domain A/D equalizerOFDM Modem P/S QAM decoder invert channel = frequency domain equalizer S/P quadrature amplitude modulation (QAM) encoder N-IFFT add cyclic prefix P/S D/A + transmit filter N-FFT S/P remove cyclic prefix TRANSMITTER RECEIVE R N subchannels N complex samples N complex samples N subchannels Receive filter + A/D multipath channel Bits 00110