Precoding method, transmitting device, and receiving device
A transmission scheme for transmitting a first modulated signal and a second modulated signal in the same frequency at the same time. According to the transmission scheme, a precoding weight multiplying unit multiplies a precoding weight by a baseband signal after a first mapping and a baseband signal after a second mapping and outputs the first modulated signal and the second modulated signal. In the precoding weight multiplying unit, precoding weights are regularly hopped.
1. A wireless base station apparatus comprising:
control signal generation circuitry that generates a control signal indicating whether or not to perform a precoding process on a first signal s 1 ( t ) and a second signal s 2 ( t ), t being an integer equal to greater than 0; and
transmission circuitry that transmits the control signal to a wireless terminal apparatus, wherein
in a case of performing the precoding process, a first transmission signal z 1 ( t ) and a second transmission signal z 2 ( t ) to be transmitted to the wireless terminal apparatus are generated by:
applying a power adjustment to the first signal s 1 ( t ) and the second signal s 2 ( t ),
applying the precoding process to the first signal s 1 ( t ) and the second signal s 2 ( t ) in accordance with Equation 1, and
applying a transmission to the first transmission signal z 1 ( t ) and a second transmission signal z 2 ( t ) from different antennas at a same frequency and at a same time, wherein
Equation 1 is expressible as:
(
z
1
(
t
)
z
2
(
t
)
)
=
1
2
(
e
j
0
e
j
0
e
j
θ
21
(
i
)
e
j
(
θ
21
(
i
)
+
π
)
)
(
s
1
(
t
)
s
2
(
t
)
)
,
and
θ
21
(
0
)
=
0
,
θ
21
(
1
)
=
π
2
,
where a variable i is an integer value that varies according to t, and
θ 21 (i) is a function with the variable i that is a set of 0 and 1.
2. A transmission method for a wireless base station apparatus comprising:
generating a control signal indicating whether or not to perform a precoding process on a first signal s 1 ( t ) and a second signal s 2 ( t ), t being an integer equal to greater than 0; and
transmitting the control signal to the wireless terminal apparatus, wherein
in a case of performing the precoding process, a first transmission signal z 1 ( t ) and a second transmission signal z 2 ( t ) to be transmitted to the wireless terminal apparatus are generated by:
applying a power adjustment to the first signal s 1 ( t ) and the second signal s 2 ( t ),
applying the precoding process to the first signal s 1 ( t ) and the second signal s 2 ( t ) in accordance with Equation 2, and
applying a transmission to the first transmission signal z 1 ( t ) and a second transmission signal z 2 ( t ) from different antennas at a same frequency and at a same time, wherein
Equation 2 is expressible as:
(
z
1
(
t
)
z
2
(
t
)
)
=
1
2
(
e
j
0
e
j
0
e
j
θ
21
(
i
)
e
j
(
θ
21
(
i
)
+
π
)
)
(
s
1
(
t
)
s
2
(
t
)
)
,
and
θ
21
(
0
)
=
0
,
θ
21
(
1
)
=
π
2
,
where a variable i is an integer value that varies according to t, and
θ 21 (i) is a function with a variable i that is a set of 0 and 1.
3. A wireless terminal apparatus comprising:
reception circuitry that receives a control signal and a plurality of data reception signals transmitted from a wireless base station apparatus, the control signal indicating whether or not a precoding process is applied with respect to the plurality of data reception signals; and
decoding circuitry that decodes the plurality of data reception signals based on the control signal, wherein
in a case of executing the precoding process, a first transmission signal z 1 ( t ) and a second transmission signal z 2 ( t ), t being an integer equal to greater than 0 to be transmitted to the wireless terminal apparatus are generated by:
applying a power adjustment to a first signal s 1 ( t ) and a second signal s 2 ( t ),
applying the precoding process to the first signal s 1 ( t ) and the second signal s 2 ( t ) in accordance with Equation 3, and
applying a transmission to the first transmission signal z 1 ( t ) and a second transmission signal z 2 ( t ) from different antennas at a same frequency and at a same time, wherein
Equation 3 is expressible as:
(
z
1
(
t
)
z
2
(
t
)
)
=
1
2
(
e
j
0
e
j
0
e
j
θ
21
(
i
)
e
j
(
θ
21
(
i
)
+
π
)
)
(
s
1
(
t
)
s
2
(
t
)
)
,
and
θ
21
(
0
)
=
0
,
θ
21
(
1
)
=
π
2
,
where a variable i is an integer value that varies according to t, and
θ 21 (i) is a function with a variable i that is a set of 0 and 1.
4. A reception method for a wireless terminal apparatus comprising:
receiving a control signal and a plurality of data reception signals transmitted from a wireless base station apparatus, the control signal indicating whether or not a precoding process is applied with respect to the plurality of data reception signals; and
decoding the plurality of data reception signals based on the control signal, wherein
in a case of executing the precoding process, a first transmission signal z 1 ( t ) and a second transmission signal z 2 ( t ), t being an integer equal to greater than 0 to be transmitted to the wireless terminal apparatus are generated by:
applying a power adjustment to a first signal s 1 ( t ) and a second signal s 2 ( t ),
applying the precoding process to the first signal s 1 ( t ) and the second signal s 2 ( t ) in accordance with Equation 4, and
applying a transmission to the first transmission signal z 1 ( t ) and a second transmission signal z 2 ( t ) from different antennas at a same frequency and at a same time, wherein
Equation 4 is expressible as:
(
z
1
(
t
)
z
2
(
t
)
)
=
1
2
(
e
j
0
e
j
0
e
j
θ
21
(
i
)
e
j
(
θ
21
(
i
)
+
π
)
)
(
s
1
(
t
)
s
2
(
t
)
)
,
and
θ
21
(
0
)
=
0
,
θ
21
(
1
)
=
π
2
,
where a variable i is an integer value that varies according to t, and
θ 21 (i) is a function with a variable i that is a set of 0 and 1.