JP6010866B2 - COMMUNICATION DEVICE AND COMMUNICATION METHOD - Google Patents

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 the orthogonal frequency division multiplexing communication apparatus of Patent Literature 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 the orthogonal frequency division multiplexing communication apparatus of Patent Document 1, it is necessary to perform iterative calculation processing to calculate the optimum phase for reducing the PAPR, and to control the phase for each subcarrier. Further, the orthogonal frequency division multiplex communication apparatus of Patent Document 1 cannot control the degree of PAPR reduction.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to reduce PAPR and control the degree of PAPR reduction 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,
Receiving means for receiving the transmission signal to generate a baseband signal, and generates a parallel signal of the baseband signal to serial-parallel conversion,
Receiving side shift means for generating a predetermined number of receiving side shift data by shifting the parallel signal a predetermined number of times in a predetermined direction ;
An FFT means for generating conversion data have rows fast Fourier transform of the parallel signal and the reception-side shift data,
Receiving side determination means for determining whether or not the number of elements whose values are within a predetermined range among the predetermined elements in each of the converted data matches a criterion ;
In each of the conversion data, the predetermined number of times when generating each of the reception-side shift data until the number of elements within the predetermined range of the predetermined elements matches a reference is determined. A receiving side repeating unit that repeatedly performs the processes of the receiving side shifting unit, the FFT unit, and the receiving side determining unit,
Wherein among the given element, the predetermined elements from the conversion data the number of elements whose value is within the predetermined range to meet the criteria extracted to respectively synthesized to generate synthesized data is a column vector synthesis Means,
Demodulating means for demodulating the synthesized data by a predetermined modulation method;
It is characterized by providing.

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,
Receiving a transmission signal to generate a baseband signal, serial-parallel conversion of the baseband signal to generate a parallel signal; and
A reception-side shift step of generating a predetermined number of reception-side shift data by shifting the parallel signal a predetermined number of times in a predetermined direction;
An FFT step of performing a fast Fourier transform of the parallel signal and the reception side shift data to generate conversion data;
In each of the conversion data, a receiving side determination step of determining whether or not the number of elements having a value within a predetermined range among predetermined elements meets a criterion;
In each of the conversion data, the predetermined number of times when generating each of the reception-side shift data until the number of elements within the predetermined range of the predetermined elements matches a reference is determined. A reception side repetition step of changing the reception side shift step, the FFT step, and the reception side determination step repeatedly,
Combining the predetermined elements from the conversion data whose values are within the predetermined range and having the values within the predetermined range are extracted and combined to generate combined data that is a column vector Steps,
A demodulating step of demodulating the synthesized data by a predetermined modulation method;
It is characterized by providing.

  According to the present invention, it is possible to reduce PAPR and 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 flowchart which shows an example of the operation | movement of transmission control which the communication apparatus which concerns on embodiment performs. It is a figure which shows the example of the signal point arrangement | sequence figure of the conversion data in embodiment. It is a figure which shows the example of the signal point arrangement | sequence figure of the conversion data in embodiment. It is a figure which shows the example of the determination process in the receiving side which the determination part which concerns on embodiment performs. It is a figure which shows the example of the determination process in the receiving side which the determination part 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 the baseband signal in the communication apparatus which concerns on embodiment. It is a figure which shows the BER characteristic in the communication apparatus which concerns on embodiment.

  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 replacement unit 13, an IFFT unit 14, a shift unit 15, a calculation 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, a synthesis unit 33, a determination unit 34, an FFT unit 35, a shift unit 36, and a reception unit 37. And a transmission / reception switching unit 38. 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 by a predetermined modulation method, generates a primary modulation signal, and sends it to the serial-parallel conversion unit 12. The predetermined modulation method is, for example, QPSK (Quadrature Phase-Shift Keying). The serial-parallel conversion unit 12 performs serial-parallel conversion on the primary modulation signal, generates a subcarrier modulation signal that is a parallel signal, and sends the subcarrier modulation signal to the replacement unit 13.

The replacement unit 13 divides the subcarrier modulation signal into a plurality of pieces of data having at least any element number of 2 or more, and replaces elements other than the data in the subcarrier modulation signal with 0 for each piece of data. The same number of partial data as that of the subcarrier modulation signal is generated and sent to the IFFT unit 14. When the FFT size is N, the subcarrier modulation signal is expressed by the following equation (1). The subscript T indicates that the matrix is transposed. The same applies to the following description. For example, the subcarrier modulation signal is divided into d ₀ to d _{N / 2-1} data and d _{N / 2} to d _N−1 data, and elements other than d _{0 to} d _{N / 2-1} data are set to 0. The partial data g ₀ generated by replacing with is represented by the following equation (2). Further, partial data g ₁ generated by replacing elements other than the data of d _{N / 2 to} d _{N −1} of the subcarrier modulation signal with 0 is expressed by the following equation (3).

The IFFT unit 14 performs IFFT on the plurality of partial data, generates inversely converted data, and sends the data to the shift unit 15. The inverse transformation data h ₀ corresponding to the partial data g ₀ represented by the above equation (2) and the inverse transformation data h ₁ corresponding to the partial data g ₁ represented by the above equation (3) are expressed by the following equation (4): It is represented by

  The shift unit 15 generates shift data by shifting a predetermined number of times that is a value less than N / 4 in a predetermined direction for each of the reverse conversion data, excluding the predetermined reverse conversion data. The shift data is sent to the arithmetic unit 16. It should be noted that the number of inversely-converted data that is not shifted in data is not limited to one and is arbitrary. In addition, if the information about the element of the subcarrier modulation signal d included in the partial data corresponding to the reverse conversion data that does not perform data shift is shared between the transmission side and the reception side, the reverse conversion data that does not perform data shift Can be arbitrarily determined. The predetermined direction is an arbitrarily determined direction, and may be an upward direction or a downward direction. If the number of shifts is set to a value of N / 4 or more, it cannot be correctly restored on the receiving side.

Here, as an example, the determined inverse transform data is assumed to be inverse transform data h ₀ corresponding to partial data g ₀ including the head element of subcarrier modulation signal d. In other words, the shift unit 15, when receiving the inverse transformed data represented by the above equation (4), the inverse transformed data h ₁ in a predetermined direction, and generates a shift data by a predetermined number of times a shift. The shift data generated from the inverse transform data _{h 1} represented by _C 1 · _{h 1.} C ₁ is a circulant matrix. In the circulant matrix used in the present embodiment, the value of one element of each row vector is 1, the value of an element other than the element is 0, and each row vector has an element of the immediately preceding row vector in a predetermined direction. Is a row vector shifted by one. The predetermined direction is either the left direction or the right direction.

  The calculation unit 16 adds the received inverse transform data and shift data, generates calculation data, and sends the calculation data to the determination unit 17. In the above example, the calculation data k is expressed by the following equation (5).

  The determination unit 17 calculates a PAPR (Peak-to-Average Power Ratio) of the baseband signal based on the calculation data, and determines whether or not the PAPR meets the reference. If it is determined that the PAPR does not meet the standard, the shift unit 15 is notified of this. The shift unit 15 generates new shift data by changing the number of times of shifting at least one of the inverse transform data. The calculation unit 16 and the determination unit 17 perform the above-described processing based on the new shift data. The controller 20 operates as a repeating unit that causes the shift unit 15, the calculation unit 16, and the determination unit 17 to repeatedly perform the above-described processing until it detects calculation data that matches the reference.

  When the determination unit 17 detects calculation data that matches the reference, the determination unit 17 sends the calculation data to the transmission unit 18. The determination unit 17 can be configured to repeat the above-described process a predetermined number of times to detect calculation data with the lowest PAPR, or to detect calculation data with the PAPR equal to or less than a threshold value.

  The transmission unit 18 combines the operation data to generate a baseband signal, generates a transmission signal from the baseband signal, and transmits the transmission signal to other devices via the transmission / reception switching unit 38 and the antenna 10.

  In the above example, the number of partial data is two, but the case where the number of partial data is three or more will be described. Let P be the number of partial data. P may be a natural number in the range of 1 <P <N, and the number of elements whose values are not 0 among the partial data may be different from each other. The replacement unit 13 divides the subcarrier modulation signal into a plurality of N / P pieces of data, and generates P partial data by replacing elements other than the data in the subcarrier modulation signal with 0 for each piece of data. A case will be described as an example. Each partial data is represented by the following equation (6).

Further, the inverse transformation data h _i corresponding to each partial data g _i is expressed by the following equation (7).

For example, the shift unit 15 performs a shift on the inverse transformed data h _i excluding the inverse transformed data h ₀ corresponding to the partial data g ₀ including the head element of the subcarrier modulation signal d. The shift data generated by shifting the inverse transformation data h _i represented by C _i · h _i. Even when P ≧ 3, the number of shifts is set to a value less than N / 4. The calculation unit 16 adds the inverse transform data h ₀ and the shift data C _i · h _i to generate calculation data. The calculation data k is expressed by the following equation (8). C ₀ is a unit matrix. Subsequent processing is the same as in the case of P = 2. Even in the case of P ≧ 3, the calculation data can be generated as in the case of P = 2.

  FIG. 3 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 primary modulation signal, and the serial-parallel conversion unit 12 performs serial-parallel conversion on the primary modulation signal to generate a subcarrier modulation signal that is a parallel signal. (Step S110). The replacement unit 13 divides the subcarrier modulation signal into a plurality of pieces of data having at least any element number of 2 or more, and replaces elements other than the data in the subcarrier modulation signal with 0 for each piece of data. Are generated in the same number as that of the data (step S120).

  The IFFT unit 14 performs IFFT on the plurality of partial data to generate inversely converted data (step S130). The shift unit 15 generates shift data by shifting a predetermined number of times of a value less than N / 4 in a predetermined direction for each of the reverse conversion data excluding the determined reverse conversion data (step S140). The calculation unit 16 adds the determined inverse transform data and shift data to generate calculation data (step S150).

  The determination unit 17 calculates the PAPR of the baseband signal based on the calculation data (step S160). If the PAPR does not meet the standard (step S170; N), the process returns to step S140, and the shift unit 15 changes the number of times of shifting at least one of the inverse transform data to generate new shift data, The above process is repeated. When the PAPR matches the standard (step S170; Y), the transmission unit 18 generates a baseband signal by combining the operation data, generates a transmission signal from the baseband signal, and transmits / receives the transmission / reception switching unit 38 and A transmission signal is transmitted to another device via the antenna 10 (step S180). When the transmission process in step S180 is completed, the communication device 1 ends the process.

  Processing on the receiving side will be described below. The receiving unit 37 receives a transmission signal via the antenna 10 and the transmission / reception switching unit 38, generates a baseband signal, performs serial-parallel conversion, generates a parallel signal, and sends the parallel signal to the shift unit 36. The shift unit 36 shifts the parallel signal in a predetermined direction a predetermined number of times to generate a predetermined number of reception side shift data, and sends the parallel signal and the reception side shift data to the FFT unit 35. The predetermined number is one less than the number of partial data generated on the transmission side. Information on the predetermined number is held in advance on the receiving side. Further, the predetermined direction is a direction arbitrarily determined in advance, for example, a direction opposite to the direction in which the reverse conversion data is shifted by the shift unit 15 on the transmission side.

The FFT unit 35 performs the FFT on the parallel signal and the reception side shift data, generates converted data, and sends it to the determination unit 34. When a transmission signal based on the operation data k expressed by the above equation (8) is sent, the conversion data u ₀ generated by performing the FFT on the parallel signal is expressed by the following equation (9). When the following formula (9) is modified based on the above formula (4) and the above formula (5), the following formula (10) is obtained. From the above formula (2) and the above formula (3), by extracting the first to N / 2th elements from the conversion data u ₀ represented by the following formula (10), subs included in g ₀ The elements of the carrier modulation signal d can be restored.

When the number of partial data generated on the transmission side is two, the shift unit 36 shifts the parallel signal to generate one reception side shift data. C ₁ ⁻¹ · k represents reception side shift data. The conversion data u ₁ is expressed by the following equation (11). If C ₁ ⁻¹ is an inverse matrix of the cyclic matrix C ₁ used on the transmission side, that is, if the number of shifts performed by the shift unit 36 is appropriate, the conversion data u ₁ represented by the following equation (11) among them, by extracting the N-th element from N / 2 + 1 th, it is possible to restore the element of subcarrier modulation signal d included in g _1.

Here, a method for determining whether C ₁ ⁻¹ is an inverse matrix of the cyclic matrix C ₁ used on the transmission side will be described. When the reception side shift data generated by the shift unit 36 is C _y · k, the conversion data u ₁ is expressed by the following equation (12).

The determination unit 34 determines whether or not the number of elements whose values are within a predetermined range among the predetermined elements in each conversion data matches a criterion. The predetermined element is based on a plurality of data generated by dividing the subcarrier modulation signal by the transmission side replacement unit 13. On the receiving side, information about predetermined elements is held in advance. In the above example, for example, in the conversion data u ₀ , the first to N / 2th elements are predetermined elements, and in the conversion data u ₁ , the N / 2 + 1th to Nth elements are predetermined elements. is there.

4 and 5 are diagrams illustrating examples of signal point arrangement diagrams of conversion data in the embodiment. Modulation scheme used in the modulator 11 is a QPSK, if C _y is the inverse of C _1, among the converted data u _1, the signal point arrangement diagram of a given element as in FIG. 4, It converges at the same position as the primary modulation signal. On the other hand, when C _y is not an inverse matrix of C ₁ , the signal point arrangement diagram of predetermined elements in the conversion data u ₁ is dispersed as shown in FIG. 5, for example.

6 and 7 are diagrams illustrating an example of determination processing on the reception side performed by the determination unit according to the embodiment. 6 and 7 are diagrams showing the first quadrant of the signal point arrangement diagram. The determination unit 34 sets, for example, a range in which the absolute value of the real part is 0.5 or more and 0.8 or less and the absolute value of the imaginary part is 0.5 or more and 0.8 or less as the predetermined range. . When C _y is an inverse matrix of C ₁ , predetermined elements of the conversion data u ₁ converge within a predetermined range surrounded by a solid line in FIG. On the other hand, when C _y is not an inverse matrix of C ₁ , a predetermined element of the conversion data u ₁ does not converge within a predetermined range as shown in FIG.

  The determination unit 34 determines whether or not the number of elements whose values are within a predetermined range among the predetermined elements in each conversion data matches a criterion. For the conversion data whose number of elements does not match the standard, the reception unit shift data is newly generated by changing the number of shifts by the shift unit 36, and the FFT unit 35 and the determination unit 34 are generated based on the new reception side shift data. Performs the above processing. In each conversion data, the controller 20 causes the shift unit 36, the FFT unit 35, and the determination unit 34 to store the above-described values until the number of elements having a value within a predetermined range matches a standard. An operation as a reception side repetition means for repeatedly performing the processing is performed. For example, in each conversion data, the above-described processing may be repeated until the conversion data in which the number of elements whose values are within a predetermined range among the predetermined elements is maximum is detected.

  When the determination unit 34 determines that the number of elements having a value within a predetermined range in each conversion data matches the criterion, the determination unit 34 sends the conversion data to the synthesis unit 33. The synthesizer 33 extracts and synthesizes predetermined elements from the sent conversion data, generates synthesized data that is a column vector, and sends it to the parallel-serial converter 32.

Among the conversion data u ₀ expressed by the above equation (10), the first to N / 2th elements are set to v _0, and the conversion data u ₁ expressed by the above equation (11) is N / 2 + 1th. the N-th element When v ₁ from the synthetic data r is expressed by the following equation (13).

  The parallel / serial conversion unit 32 performs parallel / serial conversion on the combined data received from the combining unit 33 and sends the combined data to the demodulation unit 31. The demodulator 31 demodulates the combined data that has been parallel-serial converted by the parallel-serial converter 32 using a predetermined modulation method, and restores the input signal.

  On the receiving side, the input signal can be restored if the number of partial data generated on the transmitting side and the information about the predetermined element targeted by the determination unit 34 can be restored. It can be carried out.

  A case where the number of partial data generated on the transmission side is 3 or more will be described. Each conversion data is expressed by the following equation (14). When the following equation (14) is modified based on the above equation (8), the following equation (15) is obtained.

Similar to the above-described example, the determination unit 34 determines whether or not the number of elements whose values are within a predetermined range among the predetermined elements in each conversion data matches the criterion. In the example of the above equation (15), whether the number of elements whose values are within a predetermined range among the elements corresponding to F · C _l ⁻¹ · C _l · F ⁻¹ · g _l meets the standard. Determine whether or not. When the determination unit 34 determines that the number of elements having a value within a predetermined range among the predetermined elements in each conversion data matches the criterion, the predetermined element of each conversion data is represented by v ₀ , v _{Assuming 1} ,..., V _l ,..., V _P−1 , the composite data r is expressed by the following equation (16). Even when the number of partial data generated on the transmission side is 3 or more, the input signal can be restored.

  FIG. 8 is a flowchart illustrating an example of a reception control operation performed by the communication device according to the embodiment. The receiving unit 37 receives a transmission signal via the antenna 10 and the transmission / reception switching unit 38, generates a baseband signal, and performs parallel-parallel conversion to generate a parallel signal (step S210). The shift unit 36 shifts the parallel signals in a predetermined direction a predetermined number of times to generate a predetermined number of reception side shift data (step S220). The FFT unit 35 performs conversion of the parallel signal and the reception side shift data to generate conversion data (step S230).

  The determination unit 34 determines whether or not the number of elements whose values are within a predetermined range among the predetermined elements in each conversion data matches a criterion. In each conversion data, when the number of elements whose values are within a predetermined range does not meet the standard (step S240; N), the conversion data whose number does not meet the standard Returning to step S220, the reception side shift data is newly generated by changing the number of times of shifting by the shift unit 36, and the above-described processing is repeated based on the new reception side shift data.

  In each conversion data, when the number of elements whose values are within a predetermined range among the predetermined elements matches the standard (step S240; Y), the synthesis unit 33 extracts the predetermined elements from the conversion data. Each is extracted and combined to generate combined data that is a column vector (step S250). The parallel / serial converter 32 performs parallel / serial conversion on the combined data, and the demodulator 31 demodulates the combined data converted in parallel / serial by the parallel / serial converter 32 using a predetermined modulation method to restore the input signal (step S260). ). When the restoration process in step S260 is completed, the communication device 1 ends the process.

  As described above, according to the communication device 1 according to the embodiment of the present invention, it is possible to reduce PAPR by performing a predetermined calculation in the OFDM communication scheme. Further, as will be described later, the degree of PAPR reduction can be controlled.

(Concrete example)
Next, effects of the invention according to the 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 embodiment. The modulation system is QPSK, the FFT size is 2048, and the PAPR CCDF (Complementary Cumulative Distribution Function) of the invention according to the embodiment, that is, the characteristics of the occurrence probability of PAPR are compared. The prior art is a method of generating a baseband signal by generating a subcarrier modulation signal from a signal obtained by modulating an input signal by a predetermined modulation method without performing the above-described arithmetic processing, and performing IFFT.

  FIG. 9 is a diagram illustrating the CCDF characteristics of the PAPR of the baseband signal in the communication device according to the embodiment. The horizontal axis is PAPR (unit: dB), and the vertical axis is PAPR CCDF. In the communication device 1 according to the embodiment, the above calculation is performed with the number of partial data being two.

  The CCDF characteristics of the prior art PAPR are shown by a thin solid line graph. In the communication device 1 according to the embodiment, the PAPR CCDF characteristic when the shift unit 15 is shifted 511 times is shown by a thick solid line graph, and the PAPR CCDF characteristic when the shift unit 15 is shifted 15 times is shown by a one-dot chain line graph. The CCDF characteristics of PAPR when shifted three times are shown by a two-dot chain line graph. In any case, it can be seen that the PAPR of the invention according to the embodiment is reduced as compared with the prior art. Since the PAPR changes depending on the number of shifts, the degree of PAPR reduction can be controlled by changing the reference in the determination unit 17 on the transmission side and the number of repetitions on the transmission side. Further, if the number of partial data is increased, the number of patterns of calculation data is increased. Therefore, it is estimated that the PAPR can be further reduced by increasing the number of partial data.

  In addition, the simulation was performed using the same signal whose values are all 0, for example, the phase of each element of the subcarrier modulation signal matches the input signal. The PAPR of the prior art when the same signal is used as the input signal is 33.1 dB. On the other hand, the PAPR of the communication device 1 according to the embodiment is 27.1 dB. Even in the case of the same signal, the PAPR of the communication device 1 according to the embodiment is reduced as compared with the prior art.

  A simulation was similarly performed for BER (Bit Error Rate). FIG. 10 is a diagram illustrating BER characteristics in the communication device according to the embodiment. 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 BER of the prior art is shown by a graph in which plot points are represented by squares. In the communication device 1 according to the embodiment, the BER when the shift unit 15 is shifted 511 times is shown by a graph in which the plot points are represented by triangles, and the BER when the shift is performed 15 times is represented by a circle in which the plot points are represented by circles. The BER when shifted three times is shown by a graph in which the plot points are represented by diamonds.

In the case where Eb / No is low, the BER of the communication device 1 according to the embodiment is deteriorated as compared with the prior art. This is when a low Eb / No, even if C _y in equation (12) is an inverse matrix of C _1, as shown in FIG. 7, among the converted data, predetermined elements This is because it does not converge within a predetermined range. On the other hand, when Eb / No is high, the BER is at the same level as in the prior art.

  From the above-described simulation, it was found that the PAPR can be reduced and the degree of reduction of the PAPR can be controlled by performing a predetermined calculation in the invention according to the embodiment.

  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. The order of the modulation unit 11 and the serial / parallel conversion unit 12 may be changed, the input signal may be serial / parallel converted and assigned to the subcarrier signal, and each data of the parallel signal may be modulated by a predetermined modulation method. In that case, the receiving side performs demodulation processing by changing the order of the demodulator 31 and the parallel-serial converter 32. The IFFT unit 14 may be configured to perform IDFT instead of IFFT, and the FFT unit 35 may be configured to perform DFT instead of FFT.

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

Claims (2)

A communication device that communicates with other devices by orthogonal frequency division multiplex communication wireless communication,
Receiving means for receiving the transmission signal to generate a baseband signal, and generates a parallel signal of the baseband signal to serial-parallel conversion,
Receiving side shift means for generating a predetermined number of receiving side shift data by shifting the parallel signal a predetermined number of times in a predetermined direction ;
An FFT means for generating conversion data have rows fast Fourier transform of the parallel signal and the reception-side shift data,
Receiving side determination means for determining whether or not the number of elements whose values are within a predetermined range among the predetermined elements in each of the converted data matches a criterion ;
In each of the conversion data, the predetermined number of times when generating each of the reception-side shift data until the number of elements within the predetermined range of the predetermined elements matches a reference is determined. A receiving side repeating unit that repeatedly performs the processes of the receiving side shifting unit, the FFT unit, and the receiving side determining unit,
Wherein among the given element, the predetermined elements from the conversion data the number of elements whose value is within the predetermined range to meet the criteria extracted to respectively synthesized to generate synthesized data is a column vector synthesis Means,
Demodulating means for demodulating the synthesized data by a predetermined modulation method;
A communication device comprising: A communication method performed by a communication device that communicates with other devices by wireless communication of an orthogonal frequency division multiplex communication method,
Receiving a transmission signal to generate a baseband signal, serial-parallel conversion of the baseband signal to generate a parallel signal; and
A reception-side shift step of generating a predetermined number of reception-side shift data by shifting the parallel signal a predetermined number of times in a predetermined direction;
An FFT step of performing a fast Fourier transform of the parallel signal and the reception side shift data to generate conversion data;
In each of the conversion data, a receiving side determination step of determining whether or not the number of elements having a value within a predetermined range among predetermined elements meets a criterion;
In each of the conversion data, the predetermined number of times when generating each of the reception-side shift data until the number of elements within the predetermined range of the predetermined elements matches a reference is determined. A reception side repetition step of changing the reception side shift step, the FFT step, and the reception side determination step repeatedly,
Combining the predetermined elements from the conversion data whose values are within the predetermined range and having the values within the predetermined range are extracted and combined to generate combined data that is a column vector Steps,
A demodulating step of demodulating the synthesized data by a predetermined modulation method;
Communication method comprising Rukoto equipped with.

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