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:
coding information bits to generate a first coded signal and a second coded signal, based on low-density parity-check (LDPC) coding and Bose-Chaudhuri-Hocquenghem (BCH) coding;
applying 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;
applying a phase change to the second precoded signal to generate a second phase-changed signal, the phase change being not applied to the first precoded signal;
inserting pilots into the first precoded signal and the second phase-changed signal; 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 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 broadcasting method according to claim 1 , wherein phases of N symbols in the second precoded signal are changed in the determined period.