Apparatus and method for transmitting and receiving data

A method of transmitting data in a data transmission apparatus, the method comprising:

• generating a plurality of key symbols by performing symbol mapping on information about an optimum key index that instructs a modified Walsh-Hadamard matrix that causes a minimum PAPR;
• generating a plurality of modified Walsh-Hadamard-transformed data symbols by performing modified Walsh-Hadamard transform on a plurality of data symbols according to a modified Walsh-Hadamard matrix that the optimum key index instructs;
• generating a plurality of inverse Fourier-transformed symbols by performing inverse Fourier transform on the plurality of key symbols and the plurality of modified Walsh-Hadamard-transformed data symbols;
• and
• transmitting the plurality of inverse Fourier-transformed symbols to a channel through at least one antenna.

An apparatus for receiving data, the apparatus comprising:

• a receiver configured to receive a plurality of digital symbols from a channel through at least one antenna;
• a Fourier transformer configured to generates a plurality of Fourier-transformed key symbols and a plurality of Fourier-transformed data symbols by performing Fourier transform on the plurality of digital symbols;
• an optimum key index generator configured to generate an optimum key index from the plurality of Fourier-transformed key symbols;
• a modified inverse Walsh-Hadamard transformer configured to generate a plurality of modified inverse Walsh-Hadamard-transformed data symbols by performing modified inverse Walsh-Hadamard transform on the plurality of Fourier-transformed data symbols according to a transposed matrix of a modified Walsh-Hadamard matrix that the optimum key index instructs;
• and
• a symbol mapper configured to convert the plurality of modified Walsh-Hadamard-transformed data symbols to a plurality of binary data signals.

A method of receiving data in a data receiving apparatus, the method comprising:

• receiving a plurality of digital symbols from a channel through at least one antenna;
• generating a plurality of Fourier-transformed key symbols and a plurality of Fourier-transformed data symbols by performing Fourier transform on the plurality of digital symbols;
• generating an optimum key index from the plurality of Fourier-transformed key symbols;
• generating a plurality of modified inverse Walsh-Hadamard-transformed data symbols by performing modified inverse Walsh-Hadamard transform on the plurality of Fourier-transformed data symbols according to a transposed matrix of a modified Walsh-Hadamard matrix that the optimum key index instructs;
• and
• converting the plurality of modified Walsh-Hadamard transformed data symbols to a plurality of binary data signals.