Orthogonal frequency division multiplexing wireless communication operable on frequency selective channel, and channel compensation method

A wireless communication system including a transmitter for transmitting data using a multipath fading channel and a receiver for receiving them from the transmitter, comprising:

• a mapper for mapping an externally received binary information sequence to at least one symbol according to the MQAM (M-ary quadrature amplitude modulation) method;
• a serial to parallel converter for converting the mapped symbols into vector data which are information transmit vectors;
• a first IDFT (inverse discrete Fourier transform) unit including m IDFT units for performing IDFT on the converted information transmit vectors;
• an interleaver for writing subchannel values of the respective transmit vectors received from the IDFT unit in an mxn memory buffer in the first direction;
• a second IDFT unit including n IDFT units for reading the subchannel values written in the first direction in the second direction when the writing in the first direction is finished, performing IDFT on the read subchannel values, and modulating them to OFDM (orthogonal frequency division multiplexing) signals;
• a third IDFT unit for modulating a pilot symbol vector for predicting an amplitude and a phase of the multipath fading channel to an OFDM signal;
• and
• a parallel to serial converter and guard interval inserter for inserting a guard interval into the signal received from the second IDFT unit, converting the guard interval inserted information transmit vector into a serial signal, transmitting the serial signal, converting the guard interval inserted pilot symbol vector into a serial signal, and transmitting it to the transmitter.

A method for compensating a channel in a wireless communication system for transmitting and receiving data using a multipath fading channel, comprising:

• (a) performing IDFT (inverse discrete Fourier transform) on information transmission vectors at least twice to modulate the vectors into OFDM (orthogonal frequency division multiplexing) signals, and transmitting the modulated signal through the multipath fading channel;
• (b) modulating a pilot symbol vector for predicting an amplitude and a phase of the multipath fading channel into an OFDM signal, and transmitting the modulated signal through the multipath fading channel;
• (c) demodulating the pilot symbol vector received through the multipath fading channel to predict the amplitude and the phase of the multipath fading channel;
• (d) compensating the amplitude and the phase of the channel multiplied to the received information transmit vectors by using the predicted amplitude and the phase of the channel;
• and
• (e) performing DFT on the compensated channel signals, averaging a noise signal value enhanced by the channel compensation in a specific interval with an amplitude of the channel with less than a mean value into a mean value within an OFDM symbol interval, and outputting the mean value,
• wherein (a) comprises performing a first IDFT on the information transmit vectors and outputting IDFT-performed signals;
• and performing a second IDET on the IDFT-performed signals to modulate them into OFDM signals, and
• wherein (d) comprises performing a first DFT for demodulating the received information transmit vectors into OFDM signals;
• and performing a second DFT on the compensated information transmit vectors and averaging a noise signal value which becomes enhanced in a specific interval with an amplitude of the channel with less than a mean value, to a mean value within a symbol interval.