Apparatus and method for minimizing a PAPR in an OFDM communication system

A transmitter for minimizing a Peak-to-Average Power Ratio (PAPR) in a multi carrier communication system, the transmitter comprising:

• at least one transmit antenna;
• a precoder for coding input symbols so that a signal rotation is generated, and generating a complex vector including the coded symbols;
• an encoder for performing a frequency-space mapping for the symbols generated as the complex vector according to a predetermined scheme;
• a random mapper for randomly mapping the symbols for which the frequency-space mapping has been performed on a frequency plane through said at least one transmit antenna;
• an Inverse Fast Fourier Transform (IFFT) unit for performing an IFFT for the symbols for which the frequency-space mapping has been performed;
• and
• a gradient algorithm unit for receiving IFFTed signals from the IFFT unit and reducing the PAPR.

A transmitter for minimizing a Peak-to-Average Power Ratio (PAPR) in a multi carrier communication system, the transmitter comprising:

• at least one transmit antenna;
• a precoder for coding input symbols so that a signal rotation is generated, and generating a complex vector including the coded symbols;
• an encoder for separating the symbols output from the precoder so as to generate a predetermined number of vectors, encoding the generated vectors by a predetermined scheme, performing a frequency-space mapping for the encoded vectors, and randomly mapping the symbols for which the frequency-space mapping has been performed on a frequency plane through said at least one transmit antenna;
• an Inverse Fast Fourier Transform (IFFT) unit for performing an IFFT for the symbols for which the frequency-space mapping has been performed;
• and
• a gradient algorithm unit for receiving IFFTed signals from the IFFT unit and reducing the PAPR.

A receiver for minimizing a Peak-to-Average Power Ratio (PAPR) in a multi carrier communication system, the receiver comprising:

• at least one reception antenna;
• a modulator for converting signals received through said at least one reception antenna into baseband signals, performing a Fast Fourier Transform (FFT) for the baseband signals, performing a demodulation for the FFTed signals, and outputting a demodulated data;
• a channel estimator for receiving the demodulated data and estimating channel coefficients representing a channel gain;
• a channel response matrix generator for generating a channel response matrix by means of the channel coefficients from the channel estimator;
• a signal combiner for outputting a vector with a predetermined size by combining the demodulated data from the demodulator with the channel response matrix generated by the channel response matrix generator according to a predetermined rule;
• and
• a first and a second signal determiner for estimating and outputting symbols transmitted from a transmitter by performing maximum likelihood decoding using the channel response matrix generated by the channel response matrix generator and the vector with the predetermined size output from the signal combiner.

A receiver for minimizing a Peak-to-Average Power Ratio (PAPR) in a multi carrier communication system, the receiver comprising:

• at least one reception antenna;
• a modulator for converting signals received through said at least one reception antenna into baseband signals, performing a Fast Fourier Transform (FFT) for the baseband signals, performing a demodulation for the FFTed signals, and outputting a demodulated data;
• a random sequence unit for storing predetermined random sequences, and separating signals of adjacent sub-carriers into predetermined groups based on the stored random sequences;
• a channel estimator for receiving signals output from the random sequence unit and estimating channel coefficients representing a channel gain;
• a channel response matrix generator for generating a channel response matrix by means of the channel coefficients from the channel estimator;
• a signal combiner for outputting a vector with a predetermined size by combining the signals output from the random sequence unit with the channel response matrix generated by the channel response matrix generator according to a predetermined rule;
• and
• a first and a second signal determiner for estimating and outputting symbols transmitted from a transmitter by performing maximum likelihood decoding using the channel response matrix generated by the channel response matrix generator and the vector with the predetermined size output from the signal combiner.

A transmission method in a transmitter for minimizing a Peak-to-Average Power Ratio (PAPR) in a multi carrier communication system, the transmitter including at least one transmit antenna, the method comprising the steps of:

• receiving a data sequence to be transmitted;
• generating a predecoded symbol sequence with the received data sequence through precoding using a preset preceding matrix;
• generate a predetermined number of vectors by grouping symbols constituting the predecoded symbol sequence into groups having a predetermined number of symbols;
• performing a frequency-space mapping for the generated vectors according to a predetermined scheme;
• allocating signals for which the frequency-space mapping has been performed to sub-carriers;
• performing an Inverse Fast Fourier Transform (IFFT) on the allocated signals;
• outputting the IFFTed signals;
• receiving the IFFTed signals;
• reducing the PAPR of the received signals;
• and
• transmitting signals having the reduced PAPR through said at least one transmit antenna.

A transmission method in a transmitter for minimizing a Peak-to-Average Power Ratio (PAPR) in a multi carrier communication system, the transmitter including at least one transmit antenna, the method comprising the steps of:

• receiving a data sequence to be transmitted;
• generating a predecoded symbol sequence with the received data sequence through precoding using a preset preceding matrix;
• performing a frequency-space mapping for the generated symbol sequence according to a predetermined scheme;
• randomly mapping symbols for which the frequency-space mapping has been performed on a frequency plane through said at least one transmit antenna;
• performing an Inverse Fast Fourier Transform (IFFF) for the symbols for which the frequency-space mapping has been performed;
• outputting IFFTed signals;
• receiving the IFFTed signals;
• reducing the PAPR of the received signals;
• and
• transmitting signals having the reduced PAPR through said at least one transmit antenna.

A transmission method in a transmitter for minimizing a Peak-to-Average Power Ratio (PAPR) in a multi carrier communication system, the transmitter including at least one transmit antenna, the method comprising the steps of:

• receiving a data sequence to be transmitted;
• generating a predecoded symbol sequence with the received data sequence through precoding using a preset preceding matrix;
• separating the generated predecoded symbol sequence to generate a predetermined number of vectors;
• encoding the generated vectors according to a predetermined scheme;
• randomly mapping the encoded vectors on a frequency plane;
• performing an Inverse Fast Fourier Transform (IFFT) for the symbols for which the frequency-space mapping has been performed;
• outputting IFFTed signals;
• receiving the IFFTed signals and reducing the PAPR;
• and
• transmitting signals having the reduced PAPR through said at least one transmit antenna.

A reception method in a receiver for minimizing a Peak-to-Average Power Ratio (PAPR) in an Orthogonal Frequency Division Multiplexing (OFDM) communication system, the receiver including at least one receive antenna, the method comprising the steps of:

• converting signals received through said at least one receive antenna to baseband signals;
• performing a Fast Fourier Transform (FFT) for the baseband signals, performing an OFDM demodulation for the FFTed signals;
• outputting OFDM demodulated signals;
• estimating channel coefficients representing a channel gain between a transmitter and the receiver by means of the OFDM demodulated signals;
• generating a channel response matrix by means of the estimated channel coefficients;
• generating a vector with a predetermined size by combining the OFDM demodulated signals with the channel response matrix according to a predetermined rule;
• and
• estimating transmission symbols by performing maximum likelihood decoding using the channel response matrix and the vector with the predetermined size.

A reception method in a receiver for minimizing a Peak-to-Average Power Ratio (PAPR) in an Orthogonal Frequency Division Multiplexing (OFDM) communication system, the receiver including at least one receive antenna, the method comprising the steps of:

• converting signals received through said at least one receive antenna to baseband signals;
• performing a Fast Fourier Transform (FFT) for the baseband signals;
• performing an OFDM demodulation for the FFTed signals;
• outputting OFDM demodulated signals;
• separating signals of adjacent sub-carriers into predetermined groups through a random sequence initially stored in a system;
• outputting the groups;
• estimating channel coefficients representing a channel gain between a transmitter and the receiver using the OFDM demodulated signals and output signals through the random sequence;
• generating a channel response matrix using the estimated channel coefficients;
• generating a vector with a predetermined size by combining the OFDM demodulated signals with the channel response matrix according to a predetermined rule;
• and
• estimating transmission symbols by performing maximum likelihood decoding using the channel response matrix and the vector with the predetermined size.