JP2014027383A - Communication device and communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a PAPR and to control the degree of reduction in the PAPR in OFDM-based communication.SOLUTION: A modulation unit 11 generates a modulation signal from an input signal, and a serial-parallel conversion unit 12 generates a subcarrier modulation signal from the modulation signal. A shift unit 14 generates a shift sequence by shifting a data sequence of which each element has the same absolute value to a prescribed direction and prescribed times. A calculation unit 13 generates after-calculation data by performing prescribed calculation to each element of the subcarrier modulation signal with the use of each element of the shift sequence. An IFFT unit 15 performs inverse fast Fourier transform of the after-calculation data, a combination unit 16 combines the calculation results to generate a baseband signal, and a determination unit 17 determines whether the peak-to-average power ratio of the baseband signal accords with a prescribed criterion. The above-mentioned processing is repeated by changing the prescribed times until a baseband signal according with the prescribed criterion is detected. A transmission unit 18 generates a transmission signal from the baseband signal, and transmits it via an antenna 10.

Description

  The present invention relates to a communication device and a communication method.

  In OFDM (Orthogonal Frequency-Division Multiplexing) communication, an input signal is subjected to subcarrier modulation, IFFT (Inverse Fast Fourier Transformation) is performed, and a baseband signal is generated. Therefore, when the number of subcarriers increases and the FFT (Fast Fourier Transformation) size increases, a baseband signal with a large peak is generated, and the PAPR (Peak-to-Average Power Ratio) ) Is high. As the PAPR increases, an amplifier having linearity in a wide range is required to transmit a signal without distortion. Therefore, techniques for reducing PAPR have been developed.

  In Patent Document 1, in order to reduce PAPR, the phase of the subcarrier modulation signal is controlled based on the optimum phase calculated by the sequential determination method before performing IFFT.

JP 2006-165781 A

  In OFDM communication, reducing PAPR is an issue. In Patent Document 1, it is necessary to perform iterative calculation processing in order to calculate the optimum phase for reducing the PAPR, and to control the phase for each subcarrier.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce PAPR and control the degree of reduction of PAPR in OFDM communication.

In order to achieve the above object, a communication device according to the first aspect of the present invention provides:
A communication device that communicates with other devices by orthogonal frequency division multiplex communication wireless communication,
Modulation means for modulating an input signal by a predetermined modulation method, assigning frequency components to subcarriers orthogonal to each other, and generating a subcarrier modulation signal;
Shift means for generating a shift sequence by shifting data a predetermined number of times in a predetermined direction for a data sequence that is a set of data of the same number as the number of elements of the subcarrier modulation signal,
Using a plurality of regions on the complex plane defined according to the modulation scheme, each element of the subcarrier modulation signal is subjected to an operation with the region to which the point on the complex plane corresponding to the element belongs. Pre-calculation data is generated by performing a predetermined calculation using an element at the same position as the element of the shift sequence so that the region to which the point on the complex plane corresponding to the element belongs is matched. Computing means;
IFFT means for performing inverse fast Fourier transform on the post-computation data;
Combining means for combining the operation results of the IFFT means to generate a baseband signal;
Determining means for calculating a peak-to-average power ratio of the baseband signal and determining whether the peak-to-average power ratio meets a predetermined criterion;
The shift means, the calculation is performed by changing the predetermined number of times that the data shift is performed on the data series in the shift means until the baseband signal whose peak-to-average power ratio matches the predetermined reference is detected. Control means for repeatedly performing the processing of the means, the IFFT means, the combining means, and the determining means;
Transmitting means for generating and transmitting a transmission signal from the baseband signal that matches the predetermined criteria;
It is characterized by providing.

Preferably, the shift means uses a data series in which the absolute value of each element is the same as the data series,
The arithmetic means multiplies each element of the subcarrier modulation signal by a predetermined amplitude coefficient whose absolute value is greater than 0 by an element at the same position as the element of the shift sequence. Multiply the value by adding.

  Preferably, the shift means converts the autocorrelation value between the data series and the same data series that has not been shifted as the data series to an autocorrelation value between the data series that has undergone an arbitrary shift of data. An arbitrary data series having higher autocorrelation characteristics is used.

A communication method according to a second aspect of the present invention includes:
A communication method performed by a communication device that communicates with other devices by wireless communication of an orthogonal frequency division multiplex communication method,
A modulation step of modulating an input signal with a predetermined modulation method, assigning frequency components to subcarriers orthogonal to each other, and generating a subcarrier modulation signal;
For a data sequence that is a set of data of the same number as the number of elements of the subcarrier modulation signal, a shift step of generating a shift sequence by shifting the data a predetermined number of times in a predetermined direction;
Using a plurality of regions on the complex plane defined according to the modulation scheme, each element of the subcarrier modulation signal is subjected to an operation with the region to which the point on the complex plane corresponding to the element belongs. Pre-calculation data is generated by performing a predetermined calculation using an element at the same position as the element of the shift sequence so that the region to which the point on the complex plane corresponding to the element belongs is matched. A calculation step;
IFFT step for performing inverse fast Fourier transform on the post-computation data;
A combining step of combining the operation results of the IFFT step to generate a baseband signal;
Determining a peak-to-average power ratio of the baseband signal and determining whether the peak-to-average power ratio meets a predetermined criterion; and
The shift step, the calculation is performed by changing the predetermined number of times that the data series is shifted in the shift step until the baseband signal in which the peak-to-average power ratio matches the predetermined criterion is detected. A control step for repeatedly performing the steps, the IFFT step, the synthesis step, and the determination step;
A transmission step of generating and transmitting a transmission signal from the baseband signal that matches the predetermined criterion;
It is characterized by providing.

Preferably, in the shift step, a data series having the same absolute value of each element is used as the data series,
In the calculation step, a predetermined positive constant is obtained by multiplying each element of the subcarrier modulation signal by a predetermined amplitude coefficient whose absolute value is greater than 0 to an element at the same position as the element of the shift sequence. Multiply the value by adding.

  Preferably, in the shifting step, an autocorrelation value between the data sequence and the same data sequence that has not been shifted as the data sequence becomes an autocorrelation value between the data sequence that has undergone an arbitrary shift of data. An arbitrary data series having higher autocorrelation characteristics is used.

  According to the present invention, it is possible to reduce PAPR and further control the degree of PAPR reduction in OFDM communication.

It is a block diagram which shows the structural example of the communication apparatus which concerns on embodiment of this invention. It is a block diagram which shows the example of a different structure of the communication apparatus which concerns on embodiment. It is a figure which shows the example of the arithmetic processing which the calculating part which concerns on embodiment performs. It is a flowchart which shows an example of the operation | movement of transmission control which the communication apparatus which concerns on embodiment performs. It is a flowchart which shows an example of the operation | movement of reception control which the communication apparatus which concerns on embodiment performs. It is a figure which shows the CCDF characteristic of PAPR of the simulated baseband signal. It is a figure which shows the simulated BER characteristic. It is a figure which shows the CCDF characteristic of PAPR of the simulated baseband signal. It is a figure which shows the simulated BER characteristic.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or equivalent parts are denoted by the same reference numerals. In the following description, IFFT (Inverse Fast Fourier Transformation) is a concept including IFFT and IDFT (Inverse Discrete Fourier Transformation). Therefore, in the embodiment of the present invention, IDFT may be performed instead of IFFT. Similarly, FFT (Fast Fourier Transformation) is a concept including FFT and DFT (Discrete Fourier Transformation). When performing IDFT and DFT, the FFT size in the following description means the DFT size.

  FIG. 1 is a block diagram illustrating a configuration example of a communication device according to an embodiment of the present invention. The communication device 1 communicates with other devices by OFDM (Orthogonal Frequency-Division Multiplexing) wireless communication. The communication device 1 includes an antenna 10, a modulation unit 11, a serial-parallel conversion unit 12, a calculation unit 13, a shift unit 14, an IFFT unit 15, a synthesis unit 16, a determination unit 17, a transmission unit 18, and a controller 20.

  The controller 20 includes a CPU (Central Processing Unit) 21, a RAM (Random Access Memory) 23, and a ROM (Read-Only Memory) 24. In order to avoid complication and to facilitate understanding, signal lines from the controller 20 to each part are omitted, but the controller 20 is connected to each part of the communication device 1 via an I / O (Input / Output) 22. The start and end of these processes and the control of the process contents are performed.

  In the RAM 23, for example, data for generating a transmission frame is stored. The ROM 24 stores a control program for the controller 20 to control the operation of the communication device 1. The controller 20 controls the communication device 1 based on the control program.

  FIG. 2 is a block diagram illustrating a different configuration example of the communication device according to the embodiment. In order to provide the above-described communication device 1 with a reception function, the communication device 1 illustrated in FIG. 2 further includes a demodulation unit 31, a parallel-serial conversion unit 32, an FFT unit 33, a reception unit 34, and a transmission / reception switching unit 35. A communication method performed by the communication device 1 using the communication device 1 shown in FIG. 2 having a transmission function and a reception function will be described below.

  The modulation unit 11 modulates the input signal with a predetermined modulation method to generate a modulated signal. For example, QPSK (Quadrature Phase-Shift Keying) is used as the modulation method. The serial / parallel converter 12 performs serial / parallel conversion on the modulated signal, assigns the frequency components to subcarriers orthogonal to each other, and generates a subcarrier modulated signal. Then, the subcarrier modulation signal is sent to the calculation unit 13. When the number of subcarriers is N, the subcarrier modulation signal d is expressed by the following equation (1). The subscript T indicates that the matrix is transposed.

  The shift unit 14 shifts data a predetermined number of times in a predetermined direction for a data sequence that is a set of data of the same number as the number of elements of the subcarrier modulation signal d to generate a shift sequence, and the arithmetic unit 13 Send to. As the data series, data series in which the absolute values of the elements are the same can be used.

  In addition, the autocorrelation value between the data series, for example, the autocorrelation value with the same data series that has not been shifted in data is higher than the autocorrelation value with the data series that has undergone arbitrary data shift. Any data series having can be used. In the case of using a data series having autocorrelation characteristics, a data series subjected to arbitrary data shift has a value of at least one element different from that of a data series not subjected to data shift. For example, a CAZAC (Constant Amplitude Zero Auto-Correlation) sequence or a PN (Pseudorandom Noise) sequence can be used as the data sequence having the same absolute value of each element and having autocorrelation characteristics.

The data series c is expressed by the following equation (2). A shift sequence c ^(k) generated by shifting data k times upward is expressed by the following equation (3).

The calculation unit 13 uses a plurality of regions on the complex plane defined according to the modulation method used in the modulation unit 11. For example, when QPSK is used in the modulation unit 11, the calculation unit 13 uses four regions with a real axis and an imaginary axis as boundaries on the complex plane. The calculation unit 13 matches each element of the subcarrier modulation signal d with the area to which the point on the complex plane corresponding to the element belongs and the area to which the point on the complex plane corresponding to the element to which the calculation is applied belongs. As described above, a predetermined calculation is performed using an element at the same position as the element of the shift sequence c ^(k) to generate post-calculation data, which is sent to the IFFT unit 15.

The calculation unit 13 uses, for example, a predetermined positive constant α and a predetermined amplitude coefficient β whose absolute value is greater than 0, and each element of the subcarrier modulation signal d is associated with the element of the shift sequence c ^(k) . Is multiplied by a value obtained by multiplying an element at the same position by an amplitude coefficient β and adding a positive constant α, to generate post-computation data. For example, when the absolute value of each element of the data series c is the same, the absolute value of the predetermined amplitude coefficient β is smaller than a value obtained by multiplying the absolute value of the element of the subcarrier modulation signal d by a positive constant α. Value. Each element h _i of post-operation data h generated by the above calculation is expressed by the following equation (4). The positive constant α and the amplitude coefficient β take into consideration the degree of reduction of PAPR (Peak-to-Average Power Ratio) and BER (Bit Error Rate) as described later. It is predetermined.

  FIG. 3 is a diagram illustrating an example of arithmetic processing performed by the arithmetic unit according to the embodiment. FIG. 3A shows the subcarrier modulation signal d on the complex plane. When QPSK is used as the predetermined modulation method, each element of the subcarrier modulation signal d is located at one of the four points represented by black circles in FIG. Let A be the absolute value of each element of the subcarrier modulation signal d.

FIG. 3B shows post-computation data h on a complex plane. In order to make the explanation easy to understand, the absolute value of each element of the data series c is set to 1. Each element h _i of the post-computation data h is a point where the values of the real part and the imaginary part are the same and the distance to the origin is α · A in each of the four regions bounded by the real axis and the imaginary axis. Located on the circumference of the radius β as the center. As shown in FIG. 3B, each element h _i of the post-computation data h is distributed on the circumference, so that the PAPR of the post-computation data is reduced compared to the subcarrier modulation signal d.

  The IFFT unit 15 performs IFFT on the post-computation data and sends the computation result to the synthesis unit 16. The synthesizer 16 synthesizes the calculation result of the IFFT unit 15 to generate a baseband signal and sends it to the determination unit 17.

  The determination unit 17 calculates the PAPR of the baseband signal and determines whether or not the PAPR meets a predetermined standard. If the PAPR of the baseband signal does not meet a predetermined criterion, the shift unit 14 changes the predetermined number of times data is shifted for the data series c and generates a new shift series. The calculation unit 13 generates new post-computation data using a new shift sequence, and the IFFT unit 15, the synthesis unit 16, and the determination unit 17 perform the above-described processing based on the new post-computation data. Repeat until the PAPR detects a baseband signal that meets the predetermined criteria. The controller 20 controls the arithmetic unit 13, the shift unit 14, the IFFT unit 15, the synthesis unit 16, and the determination unit 17 to repeat the above processing, and performs an operation as a control unit.

  When a data series having autocorrelation characteristics is used, a data series having an arbitrary data shift has a value of at least one element different from that of a data series having no data shift. Compared to the case where a data series that does not have is used, the probability that the baseband signal has a large peak value can be reduced, and the PAPR can be further reduced.

  If the PAPR of the baseband signal matches a predetermined standard, the determination unit 17 sends the baseband signal to the transmission unit 18. The determination unit 17 is configured to repeat the above-described processing until the data shift is completed, and detect a baseband signal with the lowest PAPR, or detect a baseband signal with a PAPR smaller than a predetermined value. Can do.

  The transmission unit 18 generates a transmission signal from the received baseband signal, and sends the transmission signal to another device via the transmission / reception switching unit 35 and the antenna 10.

  FIG. 4 is a flowchart illustrating an example of a transmission control operation performed by the communication device according to the embodiment. The modulation unit 11 modulates the input signal with a predetermined modulation method to generate a modulation signal, and the serial / parallel conversion unit 12 performs serial / parallel conversion on the modulation signal and assigns the frequency components to subcarriers orthogonal to each other. A modulation signal is generated (step S110).

The shift unit 14 shifts data a predetermined number of times in a predetermined direction with respect to the data sequence c to generate a shift sequence (step S120). The calculation unit 13 multiplies each element of the subcarrier modulation signal d by a value obtained by multiplying an element at the same position as the element of the shift sequence c ^{(k) by} the amplitude coefficient β and adding a positive constant α. Then, post-computation data is generated (step S130). The IFFT unit 15 performs IFFT on the post-computation data (step S140). The synthesizer 16 synthesizes the calculation result of the IFFT unit 15 to generate a baseband signal (step S150).

  The determination unit 17 calculates the PAPR of the baseband signal and determines whether or not the PAPR meets a predetermined standard (step S160). When the PAPR of the baseband signal does not meet the predetermined standard (step S170: N), the process returns to step S120, and the shift unit 14 changes the predetermined number of times of data shift for the data series c, and the above processing repeat. When the PAPR of the baseband signal matches a predetermined standard (step S170: Y), the transmission unit 18 generates a transmission signal from the received baseband signal, and transmits other signals via the transmission / reception switching unit 35 and the antenna 10. A transmission signal is sent to the device (step S180). When the transmission process in step S180 is completed, the process ends.

  Processing on the receiving side will be described below. The processing on the receiving side is the same as that in the prior art. The receiving unit 34 receives a transmission signal via the antenna 10 and the transmission / reception switching unit 35, generates a baseband signal, and sends it to the FFT unit 33. The FFT unit 33 performs serial-parallel conversion on the baseband signal, performs FFT to generate a parallel signal, and sends the parallel signal to the parallel-serial conversion unit 32.

  The parallel-serial converter 32 performs parallel-serial conversion on the parallel signal, generates a serial signal, and sends the serial signal to the demodulator 31. The demodulator 31 demodulates the serial signal using a predetermined demodulation method. The demodulator 31 performs primary demodulation on the serial signal based on the position of the point on the complex plane corresponding to the element of the serial signal to restore the input signal. In the calculation unit 13 on the transmission side, the region to which the point on the complex plane corresponding to the element of the subcarrier modulation signal d belongs and the region to which the point on the complex plane corresponding to the element after calculation belongs match. Since the predetermined calculation is performed, it is possible to restore the input signal without performing a calculation process opposite to the calculation on the reception side.

  FIG. 5 is a flowchart illustrating an example of a reception control operation performed by the communication device according to the embodiment. The receiving unit 34 receives a transmission signal via the antenna 10 and the transmission / reception switching unit 35, and generates a baseband signal (step S210). The FFT unit 33 performs serial-parallel conversion on the baseband signal and performs FFT to generate a parallel signal (step S220). The parallel / serial converter 32 performs parallel / serial conversion on the parallel signal, and the demodulator 31 demodulates the serial signal using a predetermined demodulation method (step S230). When the demodulation process in step S230 is completed, the process ends.

  As described above, according to the communication device 1 according to the embodiment of the present invention, in the OFDM communication system, the base is based on the post-computation data h generated by performing computation using the data sequence c on the subcarrier modulation signal d. By generating a band signal, PAPR can be reduced. Since the input signal can be restored without performing special processing on the receiving side, the configuration of the communication device 1 can be simplified. As will be described later, it is possible to reduce PAPR and control the degree of reduction of PAPR.

(Concrete example)
Next, the effect of the invention according to the present embodiment will be described by simulation. Using a random signal as an input signal, a simulation was performed for generating the baseband signal and repeatedly calculating the PAPR for the related art and the invention according to the present embodiment. The modulation method is QPSK, the FFT size is 2048, and the PAPR CCDF (Complementary Cumulative Distribution Function) of the invention according to the present embodiment, that is, the characteristics of PAPR occurrence probability are compared. The prior art is a method of generating a baseband signal by performing IFFT of the subcarrier modulation signal d without performing the above-described calculation.

  FIG. 6 is a diagram showing the CCDF characteristics of the PAPR of the simulated baseband signal. The horizontal axis is PAPR (unit: dB), and the vertical axis is PAPR CCDF. It is a thin line graph of CCDF characteristics of PAPR of the prior art. In the present embodiment, α is set to 1 in the above equation (4), and the value of β is changed. In this embodiment, β = 0.1 is a thick solid line graph, β = 0.2 is a one-dot chain line graph, and β = 0.3 is a two-dot chain line graph. In any case, the PAPR of the invention according to the present embodiment is reduced as compared with the prior art.

  In the case of the conventional technique, when the same signal in which the phase of each element of the subcarrier modulation signal d has the same value is used as the input signal, the PAPR is 33.1 dB. With respect to such an input signal, the PAPR when the same simulation was performed with α = 1 and β = 0.3 in this embodiment was 32.7 dB. Although the degree of reduction is small, it can be seen that PAPR is reduced even when the same signal is used.

  The simulation was similarly performed for BER. In the present embodiment, α is set to 1 in the above equation (4), and the value of β is changed. FIG. 7 is a diagram showing the simulated BER characteristics. The horizontal axis represents Eb / No (Energy per Bit to NOise power spectral density ratio), and the vertical axis represents BER. The unit of Eb / No is dB. The prior art BER is a graph in which plot points are represented by squares. In the present embodiment, β = 0.1 is a graph in which plot points are represented by triangles, and β = 0.2. The plot points are circles, and the case where β = 0.3 is a graph where the plot points are diamonds. It can be seen that BER deteriorates as β increases. When β is increased, the distance between the circles shown in FIG. 3 (b) is shortened, and affected by noise during transmission, the region where the element of the parallel signal is located and the element of the post-computation data h corresponding to the element There are cases where the area where the In such a case, the BER deteriorates because the input signal cannot be correctly restored.

  FIG. 8 is a diagram showing the PAPR CCDF characteristics of the simulated baseband signal. FIG. 9 is a diagram showing simulated BER characteristics. In the present embodiment, the same simulation was performed with α = 1.5 and β = 0.3 in the above equation (4). The PAPR of the invention according to the present embodiment is reduced as compared with the prior art. Further, the BER of the invention according to the present embodiment is improved as compared with the prior art. It can be seen that by increasing α, it is possible to reduce PAPR and prevent deterioration of BER at the same transmission rate as before.

  The ratio of the average power of the transmission signal of the invention according to the present embodiment to the average power of the transmission signal of the prior art is 101% when α = 1 and β = 0.1, α = 1, β = 0. .2 was 105%, α = 1, β = 0.3 was 110%, α = 1.5, β = 0.3 was 235%. By increasing the average power as in the case of α = 1.5 and β = 0.3, the PAPR can be reduced and the BER can be further improved as compared with the prior art.

  According to the simulation described above, in the present embodiment, it is possible to reduce the PAPR by generating the baseband signal based on the post-computation data h generated by performing the computation using the data series c on the subcarrier modulation signal d. all right. It was also found that the degree of PAPR reduction and the degree of BER improvement can be controlled by changing the positive constant α and the amplitude coefficient β.

  The embodiment of the present invention is not limited to the above-described embodiment. The modulation method of the modulation unit 11 is not limited to QPSK, and PSK (Phase Shift Keying) other than QPSK, Quadrature Amplitude Modulation (QAM), or the like can be used. For example, when 8PSK is used as the modulation method, the calculation unit 13 uses eight regions on the complex plane.

The values of the positive constant α and the amplitude coefficient β are determined on the complex plane corresponding to the region to which the point on the complex plane corresponding to the element of the subcarrier modulation signal d belongs and the element on which the operation is performed, depending on the modulation method. It is determined so that the area to which the point belongs coincides. In the example of the above equation (4), each element of the subcarrier modulation signal d is calculated using the same positive constant α and amplitude coefficient β, but the positive value determined for each element as in the following equation (5). The input signal d may be calculated using the constant α _i and the amplitude coefficient β _i . It is assumed that at least one absolute value of the amplitude coefficients β _i is greater than zero. The absolute value of the amplitude coefficient beta _i is the absolute value of the elements of the subcarrier modulation signal d, and less than the value obtained by multiplying a positive constant alpha _i corresponding to the amplitude coefficient beta _i.

  The IFFT unit 15 may be configured to perform IDFT instead of IFFT, and the FFT unit 33 may be configured to perform DFT instead of FFT.

1 communication equipment
10 Antenna
11 Modulator
12 Series-parallel converter
13 Calculation unit
14 Shift section
15 IFFT section
16 Synthesizer
17 Judgment part
18 Transmitter
20 controller (control means)
21 CPU
22 I / O
23 RAM
24 ROM
31 Demodulator
32 Parallel to serial converter
33 FFT section
34 Receiver
35 Transmission / reception switching unit

Claims (6)

A communication device that communicates with other devices by orthogonal frequency division multiplex communication wireless communication,
Modulation means for modulating an input signal by a predetermined modulation method, assigning frequency components to subcarriers orthogonal to each other, and generating a subcarrier modulation signal;
Shift means for generating a shift sequence by shifting data a predetermined number of times in a predetermined direction for a data sequence that is a set of data of the same number as the number of elements of the subcarrier modulation signal,
Using a plurality of regions on the complex plane defined according to the modulation scheme, each element of the subcarrier modulation signal is subjected to an operation with the region to which the point on the complex plane corresponding to the element belongs. Pre-calculation data is generated by performing a predetermined calculation using an element at the same position as the element of the shift sequence so that the region to which the point on the complex plane corresponding to the element belongs is matched. Computing means;
IFFT means for performing inverse fast Fourier transform on the post-computation data;
Combining means for combining the operation results of the IFFT means to generate a baseband signal;
Determining means for calculating a peak-to-average power ratio of the baseband signal and determining whether the peak-to-average power ratio meets a predetermined criterion;
The shift means, the calculation is performed by changing the predetermined number of times that the data shift is performed on the data series in the shift means until the baseband signal whose peak-to-average power ratio matches the predetermined reference is detected. Control means for repeatedly performing the processing of the means, the IFFT means, the combining means, and the determining means;
Transmitting means for generating and transmitting a transmission signal from the baseband signal that matches the predetermined criteria;
A communication device comprising: The shift means uses a data series in which the absolute value of each element is the same as the data series,
The arithmetic means multiplies each element of the subcarrier modulation signal by a predetermined amplitude coefficient whose absolute value is greater than 0 by an element at the same position as the element of the shift sequence. Multiply the sum of
The communication device according to claim 1.   The shift means has a higher autocorrelation value between the data series and the same data series that is not shifted in data as compared to an autocorrelation value between the data series and an arbitrary data shift. The communication apparatus according to claim 1, wherein an arbitrary data series having autocorrelation characteristics is used. A communication method performed by a communication device that communicates with other devices by wireless communication of an orthogonal frequency division multiplex communication method,
A modulation step of modulating an input signal with a predetermined modulation method, assigning frequency components to subcarriers orthogonal to each other, and generating a subcarrier modulation signal;
For a data sequence that is a set of data of the same number as the number of elements of the subcarrier modulation signal, a shift step of generating a shift sequence by shifting the data a predetermined number of times in a predetermined direction;
Using a plurality of regions on the complex plane defined according to the modulation scheme, each element of the subcarrier modulation signal is subjected to an operation with the region to which the point on the complex plane corresponding to the element belongs. Pre-calculation data is generated by performing a predetermined calculation using an element at the same position as the element of the shift sequence so that the region to which the point on the complex plane corresponding to the element belongs is matched. A calculation step;
IFFT step for performing inverse fast Fourier transform on the post-computation data;
A combining step of combining the operation results of the IFFT step to generate a baseband signal;
Determining a peak-to-average power ratio of the baseband signal and determining whether the peak-to-average power ratio meets a predetermined criterion; and
The shift step, the calculation is performed by changing the predetermined number of times that the data series is shifted in the shift step until the baseband signal in which the peak-to-average power ratio matches the predetermined criterion is detected. A control step for repeatedly performing the steps, the IFFT step, the synthesis step, and the determination step;
A transmission step of generating and transmitting a transmission signal from the baseband signal that matches the predetermined criterion;
A communication method comprising: In the shift step, a data series in which the absolute value of each element is the same as the data series,
In the calculation step, a predetermined positive constant is obtained by multiplying each element of the subcarrier modulation signal by a predetermined amplitude coefficient whose absolute value is greater than 0 to an element at the same position as the element of the shift sequence. Multiply the sum of
The communication method according to claim 4.   In the shift step, as the data series, an autocorrelation value between the same data series where data is not shifted is higher than an autocorrelation value between the data series where data is arbitrarily shifted 6. The communication method according to claim 4, wherein an arbitrary data series having autocorrelation characteristics is used.

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