Signal generating method and signal generating device
A transmission method for transmitting a first modulated signal and a second modulated signal in the same frequency at the same time. Each signal has been modulated according to a different modulation scheme. The transmission method applies precoding on both signals using a fixed precoding matrix, applies different power change to each signal, and regularly changes the phase of at least one of the signals, thereby improving received data signal quality for a reception device.
1. A transmission signal generating method comprising:
applying precoding to a first modulated signal s1 and a second modulated signal s2 to generate a first precoded signal z′1 and a second precoded signal z′2, the first modulated signal s1 having been modulated by a first modulation scheme at a modulation level denoted by a, the second modulated signal s2 having been modulated by a second modulation scheme at a modulation level denoted by b, and a and b being integers satisfying a<b;
performing a phase change on at least one of the first precoded signal z′1 and the second precoded signal z′2 to generate a first transmission signal z1 and a second transmission signal z2; and
outputting the first transmission signal z1 and the second transmission signal z2 respectively to be transmitted from a first antenna and a second antenna at the same time at the same frequency, the first transmission signal z1 and the second transmission signal z2 include respectively an information symbol regarding the first modulation scheme and the second modulation scheme,
the precoding being represented by a precoding matrix
F
=
1
α
2
+
1
(
ⅇ
j
0
α
×
ⅇ
j
o
α
×
ⅇ
j
0
ⅇ
j
π
)
where α=0,
a phase change scheme for the phase change being changed regularly, and
the transmission method further comprising:
performing a power change involving multiplication by a weighting factor u a and multiplication by a weighting factor u b , the weighting factor u a being used for the generation of the first transmission signal z1 from the first modulated signal s1, the weighting factor u b being used for the generation of the second transmission signal z2 from the second modulated signal s2, and the weighting factor u a and the weighting factor u b satisfying u a <u b .
2. A transmission signal generating apparatus comprising:
a weighting unit applying precoding to a first modulated signal s1 and a second modulated signal s2 to generate a first precoded signal z′1 and a second precoded signal z′2,
a phase changer performing a phase change on at least one of the first precoded signal z′1 and the second precoded signal z′2 to generate a first transmission signal z1 and a second transmission signal z2; and
a output unit transmitting the first transmission signal z1 and the second transmission signal z2 respectively to be transmitted from a first antenna and a second antenna at the same time at the same frequency, the first transmission signal z1 and the second transmission signal z2 include respectively an information symbol regarding the first modulation scheme and the second modulation scheme,
the first modulated signal s1 having been modulated by a first modulation scheme at a modulation level denoted by a, the second modulated signal s2 having been modulated by a second modulation scheme at a modulation level denoted by b, and a and b being integers satisfying a<b,
the precoding being represented by a precoding matrix
F
=
1
α
2
+
1
(
ⅇ
j
0
α
×
ⅇ
j
o
α
×
ⅇ
j
0
ⅇ
j
π
)
where α=0,
a phase change scheme for the phase change being changed regularly, and
the transmission apparatus further comprising:
a power changer performing a power change involving multiplication by a weighting factor u a and multiplication by a weighting factor u b , the weighting factor u a being used for the generation of the first transmission signal z1 from the first modulated signal s1, the weighting factor u b being used for the generation of the second transmission signal z2 from the second modulated signal s2, and the weighting factor u a and the weighting factor u b satisfying u a <u b .
3. A reception signal generating method comprising:
inputting a reception signal obtained by receiving a first transmission signal z1 and a second transmission signal z2 respectively transmitted from a first antenna and a second antenna at the same time at the same frequency, the first transmission signal z1 and the second transmission signal z2 having been generated by a predetermined generation process, the first transmission signal z1 and the second transmission signal z2 include respectively an information symbol regarding a first modulation scheme and a second modulation scheme; and
obtaining reception data by applying a demodulation process corresponding to the predetermined generation process to the reception signal based on the information symbol,
the predetermined generation process including:
applying precoding to a first modulated signal s1 and a second modulated signal s2 to generate a first precoded signal z′1 and a second precoded signal z′2; and
performing a phase change on at least one of the first precoded signal z′1 and the second precoded signal z′2 to generate the first transmission signal z1 and the second transmission signal z2,
the first modulated signal s1 having been modulated by the first modulation scheme at a modulation level denoted by a, the second modulated signal s2 having been modulated by the second modulation scheme at a modulation level denoted by b, a and b being integers satisfying a<b,
the precoding being represented by a precoding matrix
F
=
1
α
2
+
1
(
ⅇ
j
0
α
×
ⅇ
j
o
α
×
ⅇ
j
0
ⅇ
j
π
)
where α=0,
a phase change scheme for the phase change being changed regularly, and
the predetermined generation process further including:
performing a power change involving multiplication by a weighting factor u a and multiplication by a weighting factor u b , the weighting factor u a being used for the generation of the first transmission signal z1 from the first modulated signal s1, the weighting factor u b being used for the generation of the second transmission signal z2 from the second modulated signal s2, and the weighting factor u a and the weighting factor u b satisfying u a <u b .
4. A reception signal generating apparatus comprising:
an inputting unit acquiring a reception signal obtained by receiving a first transmission signal z1 and a second transmission signal z2 respectively transmitted from a first antenna and a second antenna at the same time at the same frequency, the first transmission signal z1 and the second transmission signal z2 having been generated by a predetermined generation process, the first transmission signal z1 and the second transmission signal z2 include respectively an information symbol regarding a first modulation scheme and a second modulation scheme; and
a demodulator obtaining reception data by applying a demodulation process corresponding to the predetermined generation process to the reception signal based on the information symbol,
the predetermined generation process including:
applying precoding to a first modulated signal s1 and a second modulated signal s2 to generate a first precoded signal z′1 and a second precoded signal z′2; and
performing a phase change on at least one of the first precoded signal z′1 and the second precoded signal z′2 to generate the first transmission signal z1 and the second transmission signal z2,
the first modulated signal s1 having been modulated by the first modulation scheme at a modulation level denoted by a, the second modulated signal s2 having been modulated by the second modulation scheme at a modulation level denoted by b, a and b being integers satisfying a<b,
the precoding being represented by a precoding matrix
F
=
1
α
2
+
1
(
ⅇ
j
0
α
×
ⅇ
j
o
α
×
ⅇ
j
0
ⅇ
j
π
)
where α=0,
a phase change scheme for the phase change being changed regularly, and
the predetermined generation process further including:
performing a power change involving multiplication by a weighting factor u a and multiplication by a weighting factor u b , the weighting factor u a being used for the generation of the first transmission signal z1 from the first modulated signal s1, the weighting factor u b being used for the generation of the second transmission signal z2 from the second modulated signal s2, and the weighting factor u a and the weighting factor u b satisfying u a <u b .