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 signal processing method comprising:
acquiring a reception signal based on a plurality of precoded signals z1 and z2;
demodulating the reception signal in accordance with a transmission scheme of the plurality of precoded signals z1 and z2;
performing error-correction decoding on the demodulated signal; and
acquiring audio data from the error-correction decoded signal, and externally outputting the audio data, wherein
the plurality of precoded signals z1 and z2 are transmitted in the same frequency bandwidth at the same time, the plurality of precoded signals z1 and z2 are generated by (i) selecting one matrix from among N matrices F[i] by regularly hopping between the N matrices F[i] which are each selected at least once within a predetermined time period H and (ii) multiplying the selected matrix by two baseband signals s1 and s2 that are represented by in-phase components and quadrature components, where N is an integer 1 or greater and less than H, and i is an integer from 0 to N−1,
the N matrices F[i] are two-by-two matrices that satisfy a first condition, a second condition, and a third condition,
the first condition is that x is an integer from 0 to N−1, y is an integer from 0 to N−1, and with respect to all x and all y satisfying x≠y, F[x]≠F[y] holds,
the second condition is that x is an integer from 0 to N−1, y is an integer from 0 to N−1, and with respect to all x and all y satisfying x≠y, no real or complex number k holding F[x]=k×F[y] exists,
the third condition is that the plurality of precoded signals z1 and z2, two baseband signals s1 and s2 and the N matrices F[i] satisfy Equation (1),
(
z
1
(
Ni
)
z
2
(
Ni
)
)
=
1
β
2
+
1
(
ⅇ
j
θ
11
(
Ni
)
β
×
ⅇ
j
(
θ
11
(
Ni
)
+
λ
)
β
×
ⅇ
j
θ
21
(
Ni
)
ⅇ
j
(
θ
21
(
Ni
)
+
λ
+
δ
)
)
(
s
1
(
Ni
)
s
2
(
Ni
)
)
(
1
)
where, β equals to 0,
θ 11 (Ni) and θ 21 (Ni) each indicate a phase rotation amount for a symbol number Ni,
λ indicates a phase rotation amount,
δ indicates a phase rotation amount, and
j is an imaginary unit.
2. The signal processing method of claim 1 , further comprising
detecting, from the reception signal, control information for notifying of the transmission scheme of the plurality of precoded signals z1 and z2, wherein
the demodulation of the reception signal is based on the control information.
3. The signal processing method of claim 1 , wherein
the two baseband signals s1 and s2 are the same signals.
4. A signal processing device comprising:
an acquirer that acquires a reception signal based on a plurality of precoded signals z1 and z2;
a demodulator that demodulates the reception signal in accordance with a transmission scheme of the plurality of precoded signals z1 and z2;
a decoder that performs error-correction decoding on the demodulated signal; and
an audio output that acquires audio data from the error-correction decoded signal, and externally outputs the audio data, wherein
the plurality of precoded signals z1 and z2 are transmitted in the same frequency bandwidth at the same time, and the plurality of precoded signals z1 and z2 are generated by (i) selecting one matrix from among N matrices F[i] by regularly hopping between the N matrices F[i] which are each selected at least once within a predetermined time period H and (ii) multiplying the selected matrix by two baseband signals s1 and s2 that are represented by in-phase components and quadrature components, where N is an integer 1 or greater and less than H, and i is an integer from 0 to N−1,
the N matrices F[i] are two-by-two matrices that satisfy a first condition, a second condition, and a third condition,
the first condition is that x is an integer from 0 to N−1, y is an integer from 0 to N−1, and with respect to all x and all y satisfying x≠y, F[x]≠F[y] holds,
the second condition is that x is an integer from 0 to N−1, y is an integer from 0 to N−1, and with respect to all x and all y satisfying x≠y, no real or complex number k holding F[x]=k×F[y] exists,
the third condition is that the plurality of precoded signals z1 and z2, two baseband signals s1 and s2 and the N matrices F[i] satisfy Equation (2),
(
z
1
(
Ni
)
z
2
(
Ni
)
)
=
1
β
2
+
1
(
ⅇ
j
θ
11
(
Ni
)
β
×
ⅇ
j
(
θ
11
(
Ni
)
+
λ
)
β
×
ⅇ
j
θ
21
(
Ni
)
ⅇ
j
(
θ
21
(
Ni
)
+
λ
+
δ
)
)
(
s
1
(
Ni
)
s
2
(
Ni
)
)
(
2
)
where, β equals to 0,
θ 11 (Ni) and θ 21 (Ni) each indicate a phase rotation amount for a symbol number Ni,
λ indicates a phase rotation amount,
δ indicates a phase rotation amount, and
j is an imaginary unit.
5. The signal processing device of claim 4 , further comprising
a detector that detects, from the reception signal, control information for notifying of the transmission scheme of the plurality of precoded signals z1 and z2, wherein
the demodulator demodulates the reception signal based on the control information.
6. The signal processing device of claim 4 , wherein
the two baseband signals s1 and s2 are the same signals.