Patent ID: 8718153

Claim:
A signal transmitting apparatus, comprising: a first memory that stores received data and re-orders the stored data; an inverse fast Fourier transform (IFFT) unit that stores a twiddle factor for shifting an output of IFFT by the size of a cyclic prefix, and performs the IFFT on data sequentially transmitted from the first memory on the basis of the twiddle factor; a second memory that stores data, which is to be used as the cyclic prefix, among output data from the IFFT unit; a multiplexer that generates an OFDM (orthogonal frequency division multiplexing) symbol on the basis of the cyclic prefix stored in the second memory and the IFFT value; and a controller that receives the size of the cyclic prefix from a user, and generates the twiddle factor based on a value obtained by dividing the size of the cyclic prefix that is multiplied by a predetermined value by a prescribed size of a fast Fourier transform (FFT) for the IFFT, wherein the twiddle factor is generated according to a formula: ⅇ j ⁢ 2 ⁢ π × CP_SIZE FFT_SIZE ⁢ k , and wherein a frequency conversion characteristics of the FFT is determined according to the following formula: F ( k + M ) = FFT ⁡ ( f n ⁢ ⅇ j2π ⁢ ⁢ Mn N ) .