METHOD AND APPARATUS OF SYMBOL MODULATION IN AN ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING SYSTEM AND TRANSMITTER USING THE SAME

摘要

A method and an apparatus of modulating symbols in an OFDM system and a transmitter using the same are provided to enhance a timing margin by reducing a data transmission preparing time in the transmitter. An apparatus of modulating symbols in an OFDM(Orthogonal Frequency Division Multiplexing) system includes an IFFT(Inverse Fast Fourier Transform) unit(707), a twiddling factor generating unit(701), and a CP(Cyclic Prefix) inserting unit(709). The IFFT unit converts input bit strings using an IFFT algorithm and outputs circular rotated data according to a twiddling factor. The twiddling factor generating unit generates the twiddling factor corresponding to a CP length and outputs the generated twiddling factor so as to multiply with the input strings of the IFFT unit. The CP inserting unit buffers data corresponding to the CP length from a front portion of an output string of the IFFT unit and copies the buffered data to a rear portion of the output string.