Signal generation method and signal generation device
A transmission method simultaneously transmitting a first modulated signal and a second modulated signal at a common frequency performs precoding on both signals using a fixed precoding matrix and regularly changes the phase of at least one of the signals, thereby improving received data signal quality for a reception device.
1. A broadcasting method, performed by a broadcast apparatus, the broadcasting method comprising:
multiplying a vector with a two-by-two matrix to generate a first precoded signal and a second precoded signal, the vector consisting of two encoded data;
multiplying the second precoded signal with a phase change value to generate a second phase-changed signal, the first precoded signal not being multiplied with the phase change value; and
transmitting the first precoded signal and the second phase-changed signal from a first antenna and a second antenna, respectively, on a same frequency band and at a same time, wherein
the phase change value is sequentially and periodically selected from among N phase change values, N being an integer greater than two, each of the N phase change values being selected at least once within a determined period, and
a difference between two adjacent phase change values of the N phase change values is 2n/N.
2. A reception method, performed by a reception apparatus, the reception method comprising:
receiving a first transmission signal and a second transmission signal via a first reception antenna and a second reception antenna, the first transmission signal and the second transmission signal having been transmitted from a first antenna of a broadcast apparatus and a second antenna of the broadcast apparatus, respectively, on a same frequency band and at a same time; and
decoding the first transmission signal and the second transmission signal, wherein
the first transmission signal and the second transmission signal have been generated by:
multiplying a vector with a two-by-two matrix to generate a first precoded signal and a second precoded signal, the vector consisting of two encoded data; and
multiplying the second precoded signal with a phase change value to generate a second phase-changed signal, the first precoded signal not being multiplied with the phase change value,
the phase change value having been sequentially and periodically selected from among N phase change values, N being an integer greater than two, each of the N phase change values having been selected at least once within a determined period, and
a difference between two adjacent phase change values of the N phase change values being 2n/N.