Patent ID: 7433413

Claim:
An apparatus for transmitting data on a plurality of frequency sub-channels for a plurality of successive symbol periods through a plurality of transmit antennas in an orthogonal frequency division multiplexing (OFDM) system, the apparatus comprising: a serial-to-parallel (S/P) converter-for converting information symbols received from a data source to an information symbol vector; a coder generating at least one code symbol vector using the information symbol vector in at least one symbol period; an inverse fast Fourier transformer (IFFT) unit generating at least as many transmission signal vectors as twice a number of code symbol vectors generated in the coder for the at least one symbol period, and generating transmission signal vectors by inverse-fast-Fourier-transforming the at least one code symbol vector to be transmitted on a successive sub-carrier using the transmission signal vectors; at least one auxiliary converter generating a transmission signal vector to be transmitted on a successive sub-carrier using the transmission signal vector received from the IFFT unit; a plurality of parallel-to-serial (P/S) converters converting each of the transmission signal vectors to a transmission signal stream; and a plurality of guard interval inserters inserting a guard interval into each of the transmission signal streams received from the P/S converters and transmitting the guard interval-inserted transmission signal streams through the transmit antennas, wherein the IFFT unit comprises: a separator for separating the at least one code symbol vector into an odd-numbered element and an even-numbered element; first and second constituent inverse fast Fourier transformers inverse-fast-Fourier-transforming the odd-numbered element and the even-numbered element; a multiplier multiplying an output of the second constituent inverse fast Fourier transformer by a value; and an adder adding an output of the first constituent inverses fast Fourier transformer and an output of the multiplier.