Method of signal generation and signal generating 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:
multiplying, using a power changer, a first baseband signal s 1 generated from a first set of bits by u, and multiplying a second baseband signal s 2 generated from a second set of bits by v, where u and v denote real numbers different from each other;
performing, using a phase changer, a change of phase on each of the first baseband signal s 1 multiplied by u and the second baseband signal s 2 multiplied by v, thus generating a first post-phase-change baseband signal u×s 1 ′ and a second post-phase-change baseband signal v×s 2 ′; and
applying, using a weighting unit, weighting according to a predetermined matrix F to the first post-phase-change baseband signal u×s 1 ′ and to the second post-phase-change baseband signal v×s 2 ′, thus generating the plurality of signals for transmission on the common frequency band and at the common time as 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 ( u×s 1 ′,v×s 2′) T
and the change of phase is performed on the first baseband signal s 1 multiplied by u and the second baseband signal s 2 multiplied by v by using a phase modification value sequentially selected from among N phase modification value candidates, each of the N phase modification value candidates being selected at least once within a predetermined period.
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:
a power changer multiplying a first baseband signal s 1 generated from a first set of bits by u, and multiplying a second baseband signal s 2 generated from a second set of bits by v, where u and v denote real numbers different from each other;
a phase changer performing a change of phase on each of the first baseband signal s 1 multiplied by u and the second baseband signal s 2 multiplied by v, thus generating a first post-phase-change baseband signal u×s 1 ′ and a second post-phase-change baseband signal v×s 2 ′; and
a weighting unit applying weighting according to a predetermined matrix F to the first post-phase-change baseband signal u×s 1 ′ and to the second post-phase-change baseband signal v×s 2 ′, thus generating the plurality of signals for transmission on the common frequency band and at the common time as 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 ( u×s 1 ′,v×s 2′) T
and the change of phase is performed on the first baseband signal s 1 multiplied by u and the second baseband signal s 2 multiplied by v by using a phase modification value sequentially selected from among N phase modification value candidates, each of the N phase modification value candidates being selected at least once within a predetermined period.