Method for transmitting and receiving orthogonal frequency division multiplexing signal and apparatus therefor

A method for receiving OFDM signals, comprising:

• (a) digitally converting received OFDM signals and obtaining a signal sample from the transformed signals;
• (b) detecting the starting point of an N-sized signal sample block from the signal samples, and removing a cyclic prefix;
• (c) dividing the signal sample block into L M-sized small blocks, where N, M and L are integers of 1 or more, and L=N/M;
• (d) M-point fast Fourier transforming the L small blocks;
• (e) combining the L M-point fast Fourier transformed small blocks, and generating an N-sized transform block, the N-sized transform block Zn, where n=0,1, . . . ,N−1, being coupled based on the relationship Zn=ZlM+v=Wvl, where n=lM+v,l=0,1, . . . L−1, and v=0,1, . . . ,M−1, wherein an M-point fast Fourier transform of signal sample ωml is Wvl;
• and
• (f) detecting data from the N-sized transform block, and decoding the detected data.

A method for receiving OFDM signals, comprising:

• (a) digitally converting received OFDM signals and obtaining a signal sample from the transformed signals;
• (b) detecting the starting point of an N-sized signal sample block from the signal samples, and removing a cyclic prefix;
• (b1) N-point fast Fourier transforming the N-sized signal sample block;
• (b2) compensating the distortion due to a channel by multiplying the N-point fast Fourier transformed value in step (b1) by the tap coefficients of a frequency domain equalizer;
• (b3) N-point inverse fast Fourier transforming N samples in which the distortion is compensated in step (b2);
• (c) dividing the signal sample block into L M-sized small blocks, where N, M and L are integers of 1 or more, and L=N/M;
• (d) M-point fast Fourier transforming the L small blocks;
• (e) combining the L M-point fast Fourier transformed small blocks, and generating an N-sized transform block;
• and
• (f) detecting data from the N-sized transform block, and decoding the detected data.

An apparatus for transmitting OFDM signals, comprising:

• an encoder for encoding OFDM signals;
• a transmission deinterleaver for forming N encoded code data into a block, and dividing the block into L M-sized small blocks, where N, M and L are integers of 1 or more, and L=N/M, the N code data forming the block being expressed by Xn, where n=0,1, . . . ,N−1, the signal transmission deinterleaver dividing each of the L small blocks Xv1, where l=0,1, . . . ,L−1, based on the relationship Xvl=XlM+v=Xn, where n=lM+v,l=0,1, . . . ,L−1, and v=0,1, . . . ,M−1;
• L M-point inverse fast Fourier transformers for M-point inverse fast Fourier transforming the L small blocks;
• a signal transmission interleaver for combining L M-point inverse fast Fourier transformed small blocks, thereby generating an N-sized inverse transformed block;
• a cyclic prefix adder for adding a cyclic prefix to the N-sized inversely transformed block;
• and
• a digital-to-analog converter for analog-transforming the inversely-transformed block to which the cyclic prefix is added and transmitting the analog-transformed signal.

An apparatus for receiving OFDM signals, comprising:

• an analog-to-digital converter for obtaining signal samples by digital-converting received OFDM signals;
• a cyclic prefix remover for finding the starting point of an N-sized signal sample block from the signal samples, and removing a cyclic prefix;
• a signal receiving deinterleaver for dividing the signal sample block into L M-sized small blocks, where N, M and L are integers of 1 or more, and L=N/M;
• L M-point fast Fourier transformers for M-point fast Fourier transforming the L small blocks;
• a signal receiving interleaver for interleaving the L M-point fast Fourier transformed small blocks, thereby generating an N-sized transform block, the signal receiving interleaver coupling the N-sized transform block Zn,n=0,1, . . . ,N−1 based on the relationship Zn=ZlM+v=Wvl, where n=lM+v,l=0,1, . . . , L−1, and v=0,1, . . . ,M−1, wherein an M-point fast Fourier transform of signal samples ωml is Wvl;
• a detector for detecting data from the N-sized transform block;
• and
• a decoder for decoding the detected data.

An apparatus for receiving OFDM signals, comprising:

• an analog-to-digital converter for obtaining signal samples by digital-converting received OFDM signals:
• a cyclic prefix remover for finding the starting point of an N-sized signal sample block from the signal samples, and removing a cyclic prefix;
• an N-point fast Fourier transformer for N-point fast Fourier transforming an N-sized signal sample block in which a cyclic prefix is removed by the cyclic prefix remover;
• a frequency domain equalizer for compensating for the distortion caused by a channel by multiplying the values transformed by the N-point fast Fourier transformer by the tap coefficients of the frequency domain equalizer;
• an N-point inverse fast Fourier transformer for inversely transforming the N samples having distortion compensated for by the frequency domain equalizer and outputting the inversely transformed samples to a receiving deinterleaver;
• a signal receiving deinterleaver for dividing the signal sample block into L M-sized small blocks, where N, M and L are integers of 1 or more, and L=N/M;
• L M-point fast Fourier transformers for M-point fast Fourier transforming the L small blocks;
• a signal receiving interleaver for interleaving the L M-point fast Fourier transformed small blocks, thereby generating an N-sized transform block;
• a detector for detecting data from the N-sized transform block;
• and
• a decoder for decoding the detected data.

An apparatus for transmitting OFDM signals, the apparatus comprising:

• a pre-processor for encoding an input data sequence and converting the encoded data to parallel data;
• a block signal domain transformer for dividing the encoded data into blocks of predetermined sizes, inserting “0” at the first data position of each block, transforming each block into a time domain signal, and combining time domain signals;
• a pilot signal adder for converting pilot tones, which are to be inserted at positions other than a predetermined position among the positions at which “0” has been inserted in the block signal domain transformer, into time domain pilot signals, and adding the pilot signals to the time domain signals output by the block signal domain transformer;
• and
• a post-processor for converting the resultant signals of the pilot signal adder to serial signals, adding a cyclic prefix to each of the converted signals, converting the resultant signals to analog signals, and transmitting the analog signals.

An apparatus for receiving OFDM signals, comprising:

• a pre-processor for converting a received OFDM signal to a digital signal, removing a cyclic prefix from the digital signal, converting the resultant signal to parallel signals of predetermined sizes, and transforming each of the parallel signals to a frequency domain signal;
• a channel estimator for inserting virtual pilot tones at predetermined positions of the frequency domain signal, extracting the virtual pilot tones and pilot tones added upon transmission, and estimating channel characteristics from the extracted virtual pilot tones and pilot tones;
• an equalizer for compensating for distortion of the output signal of the pre-processor caused by a channel, according to the estimated channel characteristics;
• an intermediate processor for converting the output signal of the equalizer to a time domain signal and removing pilot signals from the time domain signal;
• a signal domain transformer for transforming the output signal of the intermediate processor to a frequency domain signal;
• and
• a post-processor for detecting transmission data from the frequency domain signal, converting the detected data to serial data, and decoding the serial data.

A method of transmitting OFDM signals, comprising:

• (a) encoding an input data sequence, and converting encoded data to parallel data;
• (b) dividing the encoded data into blocks of predetermined sizes and inserting “0” at the first position of each block;
• (c) transforming each block to which “0” is inserted, to a time domain signal, and combining the time domain signals;
• (d) transforming pilot tones, which are to be inserted at positions other than a predetermined position among the positions at which “0” has been inserted, into time domain pilot signals, and adding each of the pilot signals to the time domain signal of each block;
• and
• (e) converting the resultant signal of the step (d) to a serial signal, adding a cyclic prefix to the converted signal, converting the resultant signal to an analog signal, and transmitting the analog signal.

A method of receiving OFDM signals, comprising:

• (a) converting a received signal into a digital signal, removing a cyclic prefix from the digital signal, converting the resultant signal into parallel signals of predetermined sizes, and converting each parallel signal to a frequency domain signal;
• (b) inserting a virtual pilot tone at predetermined positions of the frequency domain signal and extracting the virtual pilot tone and pilot tones added upon transmission;
• (c) estimating channel characteristics from the extracted virtual pilot tone and pilot tones;
• (d) compensating for distortion caused by a channel with respect to the frequency domain signal, according to the estimated channel characteristics;
• (e) transforming a distortion-compensated signal into a time domain signal and removing pilot signals from the time domain signal;
• and
• (f) detecting transmission data by transforming the resultant signals of the step (e) to a frequency domain signal, and converting the detected transmission data to serial data and decoding the serial data.