Signal generation method and signal generation device
View Patent ↗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 signal generation method for generating, from a plurality of baseband signals, a plurality of signals for transmission on a common frequency band and at a common time, comprising the steps of:
generating, using an encoder, M first encoded blocks usable as a first set of bits and M second encoded blocks usable as a second set of bits using a predetermined error-correcting block coding method, where M is a natural number;
performing, using a phase changer, a change of phase on each of a first baseband signal s 1 generated from the first set of bits and a second baseband signal s 2 generated from the second set of bits, thus generating a first post-phase change baseband signal s 1 ′ and a second post-phase change baseband signal s 2 ′, each including M symbols; and
applying, using a weighting unit, weighting to the first post-phase change baseband signal s 1 ′ and to the second post-phase change baseband signal s 2 ′ according to a predetermined matrix F, thus generating the plurality of signals for transmission on the common frequency band and at the common time as a combination of M pairs of a first weighted signal z 1 and a second weighted signal z 2 , wherein
the first weighted signal z 1 and the second weighted signal z 2 satisfy the relation:
( z 1 ,z 2) T =F ( s 1 ′,s 2′) T
and the change of phase is performed on the first baseband signal s 1 and the second baseband signal s 2 using a phase modification value sequentially selected from among N phase modification value candidates.
2. A signal generation apparatus for generating, from a plurality of baseband signals, a plurality of signals for transmission on a common frequency band and at a common time, comprising:
an encoder generating M first encoded blocks usable as a first set of bits and M second encoded blocks usable as a second set of bits using a predetermined error-correcting block coding method, where M is a natural number;
a phase changer performing a change of phase on each of a first baseband signal s 1 generated from the first set of bits and a second baseband signal s 2 generated from the second set of bits, thus generating a first post-phase change baseband signal s 1 ′ and a second post-phase change baseband signal s 2 ′, each including M symbols; and
a weighting unit applying weighting to the first post-phase change baseband signal s 1 ′ and to the second post-phase change baseband signal s 2 ′ according to a predetermined matrix F, thus generating the plurality of signals for transmission on the common frequency band and at the common time as a combination of M pairs of a first weighted signal z 1 and a second weighted signal z 2 , wherein
the first weighted signal z 1 and the second weighted signal z 2 satisfy the relation:
( z 1 ,z 2) T =F ( s 1 ′,s 2′) T
and the change of phase is performed on the first baseband signal s 1 and the second baseband signal s 2 using a phase modification value sequentially selected from among N phase modification value candidates.