Transmission device and transmission method

A transmission method comprising:

• generating first to fourth pre-coded symbols zd1(t)-zd4(t) by pre-coding first to fourth modulation symbols s1(t)-s4(t) using a precoding matrix;
• generating second to fourth phase changed symbols z2(t)-z4(t) by regularly phase changing at least one pre-coded symbol of the second to the fourth pre-coded symbols zd2(t)-zd4(t) by using M phase changing values at times other than a first time, M being an integer of 2 or more;
• and
• transmitting the first pre-coded symbols zd1(t) and the second to the fourth phase-changed symbols z2(t)-z4(t) from different transmission antennas.

A reception device comprising:

• reception circuitry which, in operation, receives four multiplexed symbols rm(t) by the four reception antennas respectively;
• and
• signal processing circuitry which, in operation, separates the four multiplexed symbols rm(t) into first to fourth symbols rs1(t)-rs4(t), wherein
• the first to the fourth symbols rs1(t)-rs4(t) are generated by:
• pre-coding first to fourth modulation symbols s1(t)-s4(t) using a precoding matrix to generate first to fourth pre-coded symbols zd1(t)-zd4(t),
• regularly phase changing, by using M phase change values at times other than a first time, at least one pre-coded symbol of the second to the fourth pre-coded symbols zd2(t)-zd4(t) to generate second to fourth phase changed symbols z2(t)-z4(t), M being an integer of 2 or more, and
• transmitting, from different transmission antennas, the first pre-coded symbols zd1(t) and the second to the fourth phase-changed symbols z2(t)-z4(t).

A reception method comprising:

• receiving four multiplexed symbols rm(t) by the four reception antennas respectively;
• and
• separating the four multiplexed symbols rm(t) into first to fourth symbols rs1(t)-rs4(t), wherein
• the first to the fourth symbols rs(t)-rs(t) are generated by:
• pre-coding first to fourth modulation symbols s1(t)-s4(t) using a precoding matrix to generate first to fourth pre-coded symbols zd1(t)-zd4(t),
• regularly phase changing, by using M phase change values at times other than a first time, at least one pre-coded symbol of the second to fourth pre-coded symbols zd2(t)-zd4(t) to generate second to fourth phase changed symbols z2(t)-z4(t), M being an integer of 2 or more, and
• transmitting, from different transmission antennas, the first pre-coded symbols zd1(t) and the second to the fourth phase-changed symbols z2(t)-z4(t).