Precoding method, transmitting device, and receiving device

Abstract

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.

Claims

1. A reception method comprising: receiving a reception OFDM signal based on a plurality of precoded signals z1 and z2 with one or more antennas; demodulating the reception OFDM 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 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 i is an integer from 0 to N1, 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 N1, y is an integer from 0 to N1, and with respect to all x and all y satisfying xy, F[x]F[y] holds, the second condition is that x is an integer from 0 to N1, y is an integer from 0 to N1, and with respect to all x and all y satisfying xy, no real or complex number k holding F[x]=kF[y] exists, the third condition is that the plurality of precoded signals z1 and z2 are calculated by multiplying the N matrices F[i] and the two baseband signals sl and s2, the N matrices F[i] satisfying Equation (1), $\begin{array}{cc}F\left[i\right]=\frac{1}{\sqrt{{}^2+1}}\left(\begin{array}{cc}{}^{j{}_{11}\left(i\right)}& {}^{j\left({}_{11}\left(i\right)+\right)}\\ {}^{j{}_{21}\left(i\right)}& {}^{j\left({}_{21}\left(i\right)++\right)}\end{array}\right)& \left(1\right)\end{array}$ where, is a positive real number, .sub.11(i) and .sub.21(i) each indicate a phase rotation amount [radian] for a symbol number Ni, indicates a phase rotation amount [radian], indicates a phase rotation amount [radian], and j is an imaginary unit.

2. The reception method of claim 1, further comprising detecting, from the reception OFDM signal, control information for notifying of the transmission scheme of the plurality of precoded signals z1 and z2, wherein the demodulation of the reception OFDM signal is based on the control information.

3. The reception method of claim 1, wherein the two baseband signals s1 and s2 are the same signals.

4. A reception apparatus comprising: an receiver that receives a reception OFDM signal based on a plurality of precoded signals z1 and z2 with one or more antennas; a demodulator that demodulates the reception OFDM 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 and (ii) multiplying the selected matrix by two baseband signals sl and s2 that are represented by in-phase components and quadrature components, where N is an integer 1 or greater, and i is an integer from 0 to N1, 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 N1, y is an integer from 0 to N1, and with respect to all x and all y satisfying xy, F[x]F[y] holds, the second condition is that x is an integer from 0 to N1, y is an integer from 0 to N1, and with respect to all x and all y satisfying xy, no real or complex number k holding F[x]=kF[y] exists, the third condition is that the plurality of precoded signals z1 and z2 are calculated by multiplying the N matrices F[i] and the two baseband signals s1 and s2, the N matrices F[i] satisfying Equation (2), $\begin{array}{cc}F\left[i\right]=\frac{1}{\sqrt{{}^2+1}}\left(\begin{array}{cc}{}^{j{}_{11}\left(i\right)}& {}^{j\left({}_{11}\left(i\right)+\right)}\\ {}^{j{}_{21}\left(i\right)}& {}^{j\left({}_{21}\left(i\right)++\right)}\end{array}\right)& \left(2\right)\end{array}$ where, is a positive real number, and 1, .sub.11(Ni) and .sub.21(Ni) each indicate a phase rotation amount [radian] for a symbol number Ni, indicates a phase rotation amount [radian], indicates a phase rotation amount [radian], and j is an imaginary unit.

5. The reception apparatus of claim 4, further comprising a detector that detects, from the reception OFDM signal, control information for notifying of the transmission scheme of the plurality of precoded signals z1 and z2, wherein the demodulator demodulates the reception OFDM signal based on the control information.

6. The reception apparatus of claim 4, wherein the two baseband signals s1 and s2 are the same signals.

Description

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