Transmitter, receiver, data transmission method and data reception method

A receiver comprising:

• a reception unit configured to receive a first symbol and a second symbol;
• and
• a demodulator configured to demodulate the received first symbol and the received second symbol, wherein:
• the first symbol is generated by modulating a data word using a first mapping, and the second symbol is generated using a second mapping of said data word,
• the first mapping is a mapping for a QPSK modulation, and
• the second mapping is a mapping where a constellation point of the second symbol has a line-symmetric relationship with a constellation point of the first symbol, with respect to a real axis, wherein:
• a constellation point obtained by adding the first symbol and the second symbol is identical to a constellation point for a BPSK modulation.

A data transmission method performed by a transmitter, the data transmission method comprising:

• generating a first symbol by modulating a data word using a first mapping, and generating a second symbol using a second mapping of the data word;
• and
• transmitting the generated first symbol and the generated second symbol, wherein:
• the first mapping is a mapping for a QPSK modulation, and
• the second mapping is a mapping where a constellation point of the second symbol has a line-symmetric relationship with a constellation point of the first symbol, with respect to a real axis, wherein:
• a constellation point obtained by adding the first symbol and the second symbol is identical to a constellation point for a BPSK modulation.

A data reception method performed by a receiver, the data reception method comprising:

• receiving a first symbol and a second symbol;
• and
• demodulating the received first symbol and the received second symbol, wherein;
• the first symbol is generated by modulating a data word using a first mapping, and the second symbol is generated using a second mapping of the data word,
• the first mapping is a mapping for a QPSK modulation, and
• the second mapping is a mapping where a constellation point of the second symbol has a line-symmetric relationship with a constellation point of the first symbol, with respect to a real axis, wherein;
• a constellation point obtained by adding the first symbol and the second symbol is identical to a constellation point for a BPSK modulation.