Patent ID: 8295156

Claim:
A transmitting apparatus for extending a guard interval of data transmitted to terminals which are predicted to have delay extension or a timing error greater than a guard interval in an Orthogonal Frequency Division Multiple Access (OFDMA) system, comprising: a guard interval extension processing means for generating symbols with a guard interval extended by copying a part of a current symbol and pasting the copied part to a last part of a previous symbol; a Fourier Transform (FT) processing means for receiving the processed symbols from the guard interval extension processing means and performing an FT process on the received processed symbols; an Inverse Fast Fourier Transform (IFFT) processing means for performing an IFFT process on the FT processed symbols from the FT processing means; a mapping processing means for mapping outputs of the FT processing means to input points of the IFFT processing means to load the FT processed frequency-domain data on corresponding sub-carriers; and a cyclic prefix insertion means for inserting a cyclic prefix code to output of the IFFT processing means, wherein the guard interval extension processing means additionally copies a part of data adjacent to the copied data for extending a guard interval and pastes the part of adjacent data to a previous symbol in order to reduce difference between the copied data and original data that are transmitted, wherein the mapping processing means allocates sub-carriers using a window to reduce tail part of a sub-carrier.