Apparatus and method for transmitting/receiving preamble sequence in orthogonal frequency division multiplexing communication system using plurality of transmission antennas

An apparatus for channel estimation in an OFDM (Orthogonal Frequency Division Multiplexing) communication system that transmits preamble sequences over N Tx (Transmission) antennas and uses M Rx (Reception) antennas, comprising:

• a first matrix synthesizer for receiving predetermined N preamble sequences related to the N Tx antennas to synthesize a first matrix;
• a second matrix synthesizer for receiving M Rx signals from the M Rx antennas to synthesize a second matrix;
• and
• a matrix multiplier for multiplying the first matrix by the second matrix, and estimating a channel response in a time domain.

A method for channel estimation in an OFDM (Orthogonal Frequency Division Multiplexing) communication system that transmits preamble sequences over N Tx (Transmission) antennas and uses M Rx (Reception) antennas, comprising the steps of:

• a) receiving predetermined N preamble sequences related to the N Tx antennas to synthesize a first matrix;
• b) receiving M Rx signals from the M Rx antennas to synthesize a second matrix;
• and
• c) multiplying the first matrix by the second matrix, and estimating a channel response in a time domain.

An apparatus for generating a preamble sequence in an OFDM (Orthogonal Frequency Division Multiplexing) communication system that uses A sub-carriers in a frequency domain and uses N Tx (Transmission) antennas, comprising:

• N sequence generators for each generating a sequence of a length of ‘B/N’ by dividing B sub-carriers from among the A sub-carriers by the ‘N’ indicative of the number of the Tx antennas, mapping individual components of the sequence to the B/N sub-carriers from among the A sub-carriers on a one by one basis in order to assign the components of the sequence to the B/N sub-carriers, and assigning null data to remaining sub-carriers other than the B/N sub-carriers from among the A-sub-carriers, such that a preamble sequence in a frequency domain of a corresponding Tx antenna is generated;
• N IFFT (Inverse Fast Fourier Transform) units, are connected to each of the N preamble sequence generators, for receiving output signals of the preamble sequence generators, and IFFT-processing the received signals, such that each of the N IFFT units generates a preamble sequence in a time domain of a corresponding Tx antenna;
• and
• transmitters connected to the N IFFT units, each transmitter converts the IFFT-processed signal into a serial data signal, inserts a predetermined guard interval signal into the serial data signal, and transmits the resultant signal.

A method for generating a preamble sequence in an OFDM (Orthogonal Frequency Division Multiplexing) communication system that uses A sub-carriers in a frequency domain and uses N Tx (Transmission) antennas, comprising the steps of:

• a) generating N sequences, each having a length of ‘B/N’, by dividing B sub-carriers from among the A sub-carriers by the ‘N’ indicative of the number of the Tx antennas;
• b) mapping, for each of the N sequences, individual components of the sequence to B/N sub-carriers from among the A sub-carriers on a one by one basis in order to assign the components of the sequence to the B/N sub-carriers, and assigning null data to remaining sub-carriers other than the B/N sub-carriers from among the A-sub-carriers, such that N preamble sequences in frequency domains of corresponding Tx antennas are generated;
• c) IFFT (Inverse Fast Fourier Transform)—processing the N preamble sequences of the frequency domains, and generating N preamble sequences in time domains of the corresponding Tx antennas;
• and
• d) converting each of the N preamble sequence in the time domains into a serial data signal, inserting a predetermined guard interval signal into the serial data signal, and transmits the resultant signal.