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 broadcast apparatus comprising:
a signal processor configured to:
code information bits to generate a first coded signal and a second coded signal;
apply a precoding to the first coded signal and the second coded signal according to a determined matrix F to generate a first precoded signal and a second precoded signal;
apply a phase change to the second precoded signal to generate a second phase-changed precoded signal, the phase change not being applied to the first precoded signal; and insert pilots into the first precoded signal and the second phase-changed precoded signal; and
a transmitter configured to transmit the first pilot-inserted precoded signal and the second pilot-inserted 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 uses a phase change value sequentially 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 2π/N.
2. The broadcast apparatus according to claim 1 , wherein phases of N symbols in the second precoded signal are changed in the determined period.