JP6108543B2 - Peak reduction apparatus and peak reduction method - Google Patents

Description

  The present invention relates to multi-carrier transmission such as OFDM (Orthogonal Frequency Division Multiplexing), in particular, peak power versus average power in a MISO (Multiple Input Multiple Output) or MIMO (Multiple Input Multiple Output) communication apparatus having a plurality of transmission antennas. The invention relates to an apparatus and method for reducing the ratio.

In recent years, orthogonal frequency division multiplexing (hereinafter abbreviated as OFDM) is widely used as a wireless modulation method for terrestrial digital broadcasting, wireless LAN, and the like, in which information is transmitted on the amplitude and phase of multiple carriers. It has been.
The OFDM system is characterized in that a large amplitude peak (instantaneous peak) appears in the transmission signal when the phases of a plurality of carriers coincide. On the other hand, in a power amplifier used for amplification of transmission power on the transmission side of the transmission system, nonlinear distortion occurs when the output power approaches saturation power. If a large instantaneous peak is included in the time waveform of the input signal, EVM (Error Vector Magnitude: modulation accuracy) degradation occurs due to nonlinear distortion of the power amplifier, and the bit error rate is increased. In addition, in this case, the problem of power leakage outside the band also occurs. Moreover, although the said problem by nonlinear distortion can be solved by enlarging back-off of a power amplifier, there exists a problem that power efficiency falls.

  Thus, as a technique for reducing this instantaneous peak, a technique has been proposed in which a peak is exceeded while a filter that exceeds a threshold value is used to reduce the peak while limiting out-of-band leakage (for example, Patent Document 1). reference).

However, in the above prior art, since it is necessary to insert a peak reduction signal in the entire radio signal band, EVM degradation is inevitable.
At this time, the peak power can be reduced by reducing the peak power to average power ratio, but in this case as well, degradation of the EVM is inevitable.
That is, in the above-described conventional technology, there has been a problem that, in the multicarrier transmission, if the peak is reduced, the EVM is lowered.
Therefore, a technique relating to a peak reduction device that can sufficiently reduce the peak without causing a decrease in EVM is described in Japanese Patent Application No. 2012-021860 “Peak Reduction Device” (Hitachi Kokusai Electric Co., Ltd., Patent Document 2). Has been.

FIG. 4 is a block diagram showing an example of the configuration of a conventional peak reduction device, which is a simplified version of FIG. FIG. 5 is a signal waveform diagram for explaining the peak reduction processing. (A) is a signal waveform before the peak reduction processing, (b) is a peak reduction signal waveform, and (c) is a peak reduction processing. The signal waveform after is shown. In addition, the conventional peak reduction device of FIG. 4 is provided on the input side of the power amplifier in order to reduce the instantaneous peak appearing in the input signal of the transmission power amplifier on the transmission side of the OFDM wireless transmission system, for example. It is. In FIG. 4, the peak reduction device in the SISO (Single Input Single Output) communication system including one transmission antenna and one reception antenna is shown. In the peak reduction device, a peak is detected, a peak reduction signal is generated and synthesized with the original signal, and this process is repeated to gradually reduce the peak.
As shown in FIG. 4, the conventional peak reduction device 4 includes a selection unit 401, an IFFT (Inverse Fast Fourier Transform) unit 402, a memory 403, an addition unit 404, a selection unit 405, and a peak detection unit 406. , A peak reduction signal generation unit 407, an output control unit 408, and a transmission antenna 409.

  As shown in FIG. 4, in the conventional peak reduction device 4, the frequency domain signal is input to the 0 input contact terminal of the selection unit 401, and the selection unit 401 connects the switch to the 0 input contact terminal to thereby generate the frequency domain signal. Is output to the IFFT unit 402 in the subsequent stage. IFFT unit 402 converts the frequency domain signal input from selection unit 401 into a time domain signal, and outputs the time domain signal to memory 403, addition unit 404, and selection unit 405. The memory 403 stores the time domain signal input from the IFFT unit 402 only at the first iteration. In the first iteration, the selection unit 405 connects the switch to the 0 input contact terminal, and outputs the time domain signal input from the IFFT unit 402 to the peak detection unit 406 and the output control unit 408. The output control unit 408 performs control so that the signal input from the selection unit 405 is not output to the subsequent stage until the signal is repeatedly processed a predetermined number of times.

As shown in FIG. 5A, the peak detection unit 406 provides a threshold for the time domain signal input from the selection unit 405, and the peak “exists” when the value is larger than the threshold. And the time domain signal having the peak “present” is output to the peak reduction signal generation unit 407. As illustrated in FIG. 5B, the peak reduction signal generation unit 407 generates a time domain signal (peak reduction signal) for reducing the peak, converts the peak reduction signal into a frequency domain signal, and selects the selection unit 401. To give feedback.
Note that the peak reduction signal generation unit 407 generates a peak reduction signal using a spare carrier that is not normally used, such as an AC carrier defined by ARIB STD-B33. With the above processing, the first iteration is completed.

  In the second iteration, the selection unit 401 and the selection unit 405 connect the switch to the 1-input contact terminal, the selection unit 401 outputs the peak reduction signal input from the peak reduction signal generation unit 407 to the IFFT unit 402, The IFFT unit 402 converts the frequency domain peak reduction signal into a time domain signal. The output from the IFFT unit 402 (FIG. 5B) is input to the adder 404, and the other input of the adder 404 is the output signal from the memory 403 in which the signal of the first iteration process is stored (see FIG. 5). 5 (a)) is connected, and the peak is reduced by adding these signals (FIG. 5 (c)).

  The output signal of the adder 404 is input to the peak reduction signal generation unit 407 via the selection unit 405 and the peak detection unit 406. The peak reduction signal generation unit 407 outputs a result obtained by adding the peak reduction signal generated in the first iteration process and the peak reduction signal generated in the second iteration process as a new peak reduction signal. This peak reduction signal is fed back to the selection unit 401 again, and the peak is gradually reduced by repeating the above processing. When the predetermined number of iterations are completed, the signal after the peak reduction process is output from the output control unit 408 to the subsequent stage and transmitted from the transmission antenna 409.

Next, the case of MIMO will be described with reference to FIGS.
6 and 7 are block diagrams showing another configuration of the conventional peak reducing apparatus. 6 and 7 are provided on the input side of the power amplifier in order to reduce instantaneous peaks appearing in the input signal of the transmission power amplifier on the transmission side of the OFDM wireless transmission system, for example. Is. Moreover, the conventional peak reduction apparatus of FIG. 6 and FIG. 7 has shown the structural example provided with two transmission antennas. 6 and 7, the same components as those in FIG. 4 are denoted by the same reference numerals.

  The conventional peak reducing apparatus shown in FIG. 6 has a configuration simply including two systems that are the same as the peak reducing apparatus in the SISO system shown in FIG. 4, and each system performs peak processing by performing processing similar to that of SISO. Send the reduced signal. There are various MISO and MIMO systems such as STTC (Space Time Trellis Coding) and MLD (Maximum Likelihood Detection), but the transmission signals of all systems (in the example of FIG. There is a method based on the assumption that the frequency domain signals of both systems are received. In that case, for example, when a phenomenon such as a failure of the power amplification unit at one location on the transmission side or a case where a signal of a part of the system cannot be received due to shielding in the propagation path, etc., the reception in the configuration of FIG. Demodulation on the side becomes impossible and transmission failure occurs. Therefore, a transmission failure can be avoided by combining a plurality of signals in advance on the transmission side and outputting them from the transmission antenna.

  The conventional peak reducing apparatus shown in FIG. 7 shows a block diagram in which signals of all systems are synthesized and transmitted in advance on the transmission side. 7 is the same as the configuration shown in FIGS. 4 and 6 until the peak-reduced signals are output from the output control units 408a and 408b, but the output signal of the first system is the phase rotation unit (1) 601. The second system is input to the phase rotation unit (2) 602 and the second system is input to the phase rotation unit (3) 603 and the phase rotation unit (4) 604, and the phase rotation process is performed so that the correlation coefficient of each system becomes low. Then, the processing results of the phase rotation unit (1) 601 and the phase rotation unit (3) 603 are input to the addition unit 605a, and the processing results of the phase rotation unit (2) 602 and the phase rotation unit (4) 604 are input to the addition unit 605b. And synthesize each. The combined signals are transmitted from transmission antennas 409a and 409b, respectively.

Special table 2009-543434 gazette Japanese Patent Application No. 2012-021860

However, when peak reduction processing is performed in the MISO and MIMO configurations, peak generation can be suppressed by simply extending the conventional technology to multiple transmission systems, but transmission failures may occur depending on the MISO and MIMO methods employed. Increases nature.
In order to avoid this, when a plurality of systems of signals are synthesized in advance on the transmission side, if a peak reduction process is performed in each system and the signals are synthesized, a new peak may be generated in the synthesis result. As a result, there is a problem in that EVM degradation occurs due to nonlinear distortion of the transmission power amplifier and the bit error rate is increased.
There is also a problem of causing power leakage outside the band.
Moreover, although the said problem by nonlinear distortion can be solved by enlarging back-off of a power amplifier, there exists a problem of reducing power efficiency.

  The present invention has been made in view of the above circumstances. In a MISO and MIMO multi-carrier transmission system that synthesizes signals of a plurality of transmission systems, an information carrier is subjected to processing for reducing instantaneous peaks that occur. To provide a peak reduction device and a peak reduction method capable of limiting interference and out-of-band leakage power with high accuracy in units of subcarriers and simultaneously avoiding an increase in bit error rate and deviation from a spectrum mask. Objective.

It is another object of the present invention to provide a peak reduction device and a peak reduction method capable of omitting a common circuit when processing speed can be increased.
It is another object of the present invention to provide a peak reduction device and a peak reduction method that can reduce the circuit scale by feeding back the peak reduction processing result to the synthesized signal before synthesis.

  In order to achieve the above object, a peak reduction apparatus according to one aspect of the present invention is a transmission system using a multiple input single output (MISO) or multiple input multiple output (MIMO) communication system having M transmission antennas (M is a natural number). In a peak reduction device of a multicarrier transmission device that synthesizes and transmits signals of N systems (N is a natural number and N ≦ M) in advance, a spare carrier to which a peak reduction signal is allocated is arranged in common in each transmission system, A first IFFT unit that converts a frequency domain signal mapped by an OFDM modulation unit in the system to a time domain signal; a memory that stores the time domain signal converted by the first IFFT unit; and the first IFFT A peak detection unit for detecting a peak value equal to or greater than a predetermined threshold for the time domain signal converted by the unit, and a peak at the peak detection unit. A peak reduction signal generator that generates a time domain signal that reduces the peak value based on the detection result and generates a frequency domain peak reduction signal that has a higher specific gravity applied to the spare carrier based on the time domain signal. A second IFFT unit for converting the frequency domain peak reduction signal generated by the peak reduction signal generation unit into a time domain, a time domain signal stored in the memory, and the second IFFT unit A first adder for adding a time-domain peak reduction signal to reduce the peak, and a first peak reduction means for gradually reducing the peak each time the number of iterations is increased by repeating the series of processes. , A phase rotation unit that rotates the phase with respect to the time domain signal obtained by the first peak reduction unit, and a second addition unit that combines the N-system signals phase-rotated by the phase rotation unit , Characterized in that it comprises a second peak reducing means for performing reduction similar peak of the first peak reduction means for said second composite signal synthesized by an adder.

  The peak reducing apparatus according to one aspect of the present invention for achieving the above object is the above peak reducing apparatus, wherein the time domain signals obtained by the first peak reducing means are synthesized by N systems, and the synthesis is performed. The circuit scale is reduced by feeding back the signal to the first peak reduction means again and sharing the peak reduction processing.

  In addition, a peak reduction apparatus according to one embodiment of the present invention for achieving the above object is a MISO or MIMO communication system having M transmission antennas (M is a natural number), and N transmission systems (N is a natural number) in advance on the transmission side. In addition, in the peak reduction device of the multicarrier transmission device that synthesizes and transmits the signal of N ≦ M), the spare carrier to which the peak reduction signal is allocated is commonly arranged in each transmission system, and the frequency mapped by the OFDM modulation unit in each system An IFFT unit that converts a domain signal to a time domain signal, a phase rotation unit that rotates a phase with respect to the time domain signal converted by the IFFT unit, and a first time domain signal that is phase rotated by the phase rotation unit An adder, a memory for storing the time domain signal synthesized by the first adder, and a time domain signal synthesized by the first adder A peak detection unit that detects a peak value that is equal to or greater than a predetermined threshold, and a time domain signal that reduces the peak value based on the peak detection result in the peak detection unit, and based on the time domain signal A peak reduction signal generation unit that generates a frequency domain peak reduction signal with increased specific gravity applied to a spare carrier, and a frequency domain peak reduction signal generated by the peak reduction signal generation unit is applied to the phase rotation unit. A phase reverse rotation processing unit that performs reverse rotation processing of phase rotation, and a frequency domain peak reduction signal input from the phase reverse rotation processing unit is converted into a time domain peak reduction signal by the IFFT unit, and the time after the conversion The peak reduction signal of the region is phase-rotated by the phase rotation unit, the peak reduction signal of the time domain that has been phase rotated is synthesized by the first addition unit, and the synthesized peak reduction signal of the time domain is synthesized. Wherein a second adder for adding the memory time domain signal stored in, provided with, characterized in gradually reducing the peak each time increasing the number of iterations by iterating the above series of processing.

  In order to achieve the above object, a peak reduction method according to an aspect of the present invention is a MISO (Multiple Input Single Output) or MIMO (Multiple Input Multiple Output) communication system having M transmission antennas (M is a natural number). In the peak reduction method of the multicarrier transmission apparatus that synthesizes and transmits signals of N systems (N is a natural number and N ≦ M) in advance on the transmission side, a spare carrier to which a peak reduction signal is allocated is commonly arranged in each transmission system. A first IFFT processing step for converting a frequency domain signal mapped by the OFDM modulator in each system into a time domain signal; and a memory processing step for storing the time domain signal converted in the first IFFT processing step; , A peak value equal to or greater than a predetermined threshold value for the time domain signal converted in the first IFFT processing step. Based on the peak detection processing step to be detected and the peak detection result in the peak detection processing step, a time domain signal for reducing the peak value is generated, and the specific gravity applied to the spare carrier is increased based on the time domain signal. A peak reduction signal generation processing step for generating a peak reduction signal in the frequency domain, a second IFFT processing step for converting the frequency domain peak reduction signal generated in the peak reduction signal generation processing step into a time domain, A first addition processing step for reducing the peak by adding the time domain signal stored in the memory processing step and the time domain peak reduction signal input in the second IFFT processing step, and repeating the above series of processing A first peak reduction processing step of gradually reducing the peak each time the number of iterations increases by processing; A phase rotation processing step for phase rotation with respect to the time domain signal obtained by the peak reduction processing step, a second addition processing step for synthesizing the N systems of signals rotated in phase by the phase rotation processing step, And a second peak reduction processing step for performing peak reduction similar to the first peak reduction processing step on the synthesized signal synthesized in the second addition processing step.

According to the present invention, in a MISO and MIMO multicarrier transmission system that combines signals from a plurality of transmission systems, interference with an information carrier and out-of-band leakage power are respectively reduced in subcarriers during processing for reducing the instantaneous peak that occurs. It can be limited to high accuracy in units, and an increase in bit error rate and deviation of a spectrum mask can be avoided at the same time.
Further, when the processing speed can be increased, the common circuit can be omitted.
Further, the circuit scale can be reduced by feeding back the peak reduction processing result to the synthesized signal before the synthesis.

It is a block diagram which shows the structure of the peak reduction apparatus which concerns on Embodiment 1 of this invention. It is a block diagram which shows the structure of the peak reduction apparatus which concerns on Embodiment 2 of this invention. It is a block diagram which shows the structure of the peak reduction apparatus which concerns on Embodiment 3 of this invention. It is a block diagram which shows an example of a structure of the conventional peak reduction apparatus. It is a signal waveform diagram for explaining peak reduction processing, (a) is a signal waveform before peak reduction processing, (b) is a peak reduction signal waveform, and (c) is a signal waveform after peak reduction processing. . It is a block diagram which shows the other structure of the conventional peak reduction apparatus. It is a block diagram which shows the other structure of the conventional peak reduction apparatus.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
FIG. 1 is a block diagram showing a configuration of a peak reducing apparatus according to Embodiment 1 of the present invention. FIG. 2 is a block diagram showing the configuration of the peak reducing apparatus according to Embodiment 2 of the present invention. FIG. 3 is a block diagram showing the configuration of the peak reducing apparatus according to Embodiment 3 of the present invention. 1 to 3, the same components as those in FIGS. 4, 6, and 7 are denoted by the same reference numerals.
The peak reduction device of FIGS. 1 to 3 is provided on the input side of the power amplifier in order to reduce the instantaneous peak appearing in the input signal of the transmission power amplifier on the transmission side of the OFDM wireless transmission system, for example. is there. In addition, each of the peak reduction devices of FIGS. 1 to 3 has a configuration example including two transmission antennas. Moreover, the peak reduction apparatus of FIG. 1 and FIG. 2 is the structure which combines each after performing a peak reduction process in the 1st system and the 2nd system, and performs a peak reduction process again. In addition, the peak reduction device of FIG. 3 is configured to first synthesize the signals of the first system and the second system and then perform peak reduction processing.

<Embodiment 1>
(Configuration of Peak Reduction Device 1)
Hereinafter, the peak reducing apparatus according to Embodiment 1 of the present invention will be described in detail with reference to FIG.
As shown in FIG. 1, the peak reduction apparatus 1 according to Embodiment 1 of the present invention includes a SISO peak reduction unit 11, a phase rotation unit (1) 601, a phase rotation unit (2) 602, and an addition unit 605a. A selection unit 401c, an IFFT unit 402c, a selection unit 101c, a memory 403c, an addition unit 404c, a selection unit 405c, a peak detection unit 406c, a peak reduction signal generation unit 407c, and an output control unit 408c. , A first system processing unit including a transmission antenna 409c, a SISO peak reduction unit 12, a phase rotation unit (3) 603, a phase rotation unit (4) 604, an addition unit 605b, a selection unit 401d, IFFT unit 402d, selection unit 101d, memory 403d, addition unit 404d, selection unit 405d, peak detection unit 406d, peak reduction signal generation unit 407d, It includes an output control unit 408d, and a processing unit of the two systems eyes comprising a transmitting antenna 409 d.
In the peak reduction apparatus 1, iterative processing is performed before and after combining the signals of each system, and the processing before synthesis is set as the first iteration processing and the processing after synthesis is set as the second iteration processing.

(Operation and processing of peak reduction device 1)
Next, the operation and processing of the peak reducing apparatus according to Embodiment 1 of the present invention will be described with reference to FIG.
As shown in FIG. 1, in the peak reduction device 1, the first frequency domain signal and the second frequency domain signal are input to the SISO peak reduction unit 11 and the SISO peak reduction unit 12, respectively. The SISO peak reduction unit 11 and the SISO peak reduction unit 12 have the same configuration as that of the SISO peak reduction device shown in FIG. 4 and will not be described. The first iterative process is completed by the processes in the SISO peak reducing units 11 and 12.

  With respect to the signal of each system whose peak has been reduced, the signal of the first system is input to the phase rotation unit (1) 601 and the phase rotation unit (2) 602, and the signal of the second system is input to the phase rotation unit (3). 603 and the phase rotation unit (4) 604. In the phase rotation unit (1) 601 to the phase rotation unit (4) 604, the phase rotation processing is performed so that the correlation coefficient of each system becomes low. The output of the phase rotation unit (1) 601 and the output of the phase rotation unit (3) 603 are added by the addition unit 605a, and the output of the phase rotation unit (2) 602 and the output of the phase rotation unit (4) 604 are added. It is added in the part 605b. Then, the second iterative process is performed by performing the same process as the first iterative process on each signal synthesized by the adders 605a and 605b.

  In the first iteration of the second iterative process, the selectors 401c and 401d and the selectors 101c and 101d connect the switches to the 0 input contact terminal and output the inputs from the adders 605a and 605b to the subsequent stage. The memories 403c and 403d store the outputs of the selection units 101c and 101d only for the first time of the second iterative process. In the first iteration of the second iterative process, the selectors 405c and 405d connect the switch to the 0 input contact terminal, and the outputs of the selectors 101c and 101d are output to the peak reduction signal generator 407c via the peak detectors 406c and 406d. , 407d. Then, the peak reduction signal generation units 407c and 407d generate a combined peak reduction signal and feed it back to the selection units 401c and 401d.

  In the second iteration of the second iterative process, the selectors 401c and 401d and the selectors 101c and 101d connect the switches to one input contact terminal, and the adders 404c and 404d input from the IFFT units 402c and 402d (to the time domain signal). The input from the memories 403c and 403d in which the converted peak reduction signal) and the first signal of the second iterative process are stored is added. Then, the outputs from the addition units 404c and 404d are input to the peak reduction signal generation units 407c and 407d via the selection units 405c and 405d and the peak detection units 406c and 406d.

The peak reduction signal generation units 407c and 407d select a result obtained by adding the peak reduction signal generated in the first iteration of the second iteration and the peak reduction signal generated in the second iteration of the second iteration as a new peak reduction signal. Feedback is provided to the units 401c and 401d. When the above-described series of processing is repeated and the second iteration is completed, the signals are output from the output control units 408c and 408d to the subsequent stage and transmitted from the transmission antennas 409c and 409d.
Here, since the peak reduction signal is applied to the signal after the signals of the respective systems are combined, it is desirable that at least the spare carriers assigned for peak reduction have the same arrangement in all transmission systems.

  As described above, according to the first embodiment of the present invention, in the MISO and MIMO multi-carrier transmission system that combines signals of a plurality of transmission systems, in the process of reducing the instantaneous peak that occurs, to the information carrier Interference and out-of-band leakage power can be limited with high accuracy in units of subcarriers, and an increase in bit error rate and a deviation from a spectrum mask can be avoided at the same time.

<Embodiment 2>
(Configuration of peak reduction device 2)
Hereinafter, the peak reducing apparatus according to Embodiment 2 of the present invention will be described in detail with reference to FIG.
As shown in FIG. 2, the peak reduction apparatus 2 according to Embodiment 2 of the present invention includes a selection unit 401a, an IFFT unit 402a, a selection unit 201a, a memory 403a, an addition unit 404a, and a selection unit 405a. A peak detector 406a, a peak reduction signal generator 407a, an output controller 408a, an output controller 202a, a phase rotator (1) 601, a phase rotator (2) 602, an adder 605a, A first processing unit including a transmission antenna 409a, a selection unit 401b, an IFFT unit 402b, a selection unit 201b, a memory 403b, an addition unit 404b, a selection unit 405b, a peak detection unit 406b, a peak Reduction signal generation unit 407b, output control unit 408b, output control unit 202b, phase rotation unit (3) 603, phase rotation unit (4) 604, and addition unit It comprises a 05b, a processing unit of the two systems eyes comprising a transmitting antenna 409b.
In the peak reduction device 2, the processing speed is increased compared to the first embodiment, and the circuit size is reduced by using a common circuit for the same processing. Further, similarly to the first embodiment, the peak reduction process is performed by the first iteration process and the second iteration process.

(Operation and processing of peak reduction device 2)
Next, the operation / processing of the peak reducing apparatus according to the second embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 2, in the peak reduction device 2, the frequency domain signal of the first system and the frequency domain signal of the second system are input to the selection units 401a and 401b, respectively, and the selection unit is selected in the first iteration process. 401a and 401b connect the switch to the 0 input contact terminal to output a frequency domain signal to the IFFT units 402a and 402b. The IFFT units 402a and 402b convert the input frequency domain signal into a time domain signal and output the time domain signal to the selection units 201a and 201b. The selection units 201a and 201b connect the switch to the 0 input contact terminal and output the input signals from the IFFT units 402a and 402b to the memories 403a and 403b, the addition units 404a and 404b, and the selection units 405a and 405b. The memories 403a and 403b store outputs from the IFFT units 402a and 402b only for the first iteration.

  In the first iteration of the first iterative process, the selectors 405a and 405b connect the switches to the 0-input contact terminal so that the input signals from the IFFT units 402a and 402b are sent to the peak detectors 406a and 406b and the output controllers 408a and 408b. Output. The output control units 408a and 408b perform control so as not to output to the subsequent stage until the repetitive processing is performed as many times as necessary. The peak detectors 406a and 406b provide thresholds for the time domain signals input from the selectors 405a and 405b, detect peaks that are larger than the threshold values, and detect peak reduction signal generators 407a and 407b. Generates a time domain signal for reducing the peak signal, converts the signal into a frequency domain signal, and feeds it back to the selectors 401a and 401b.

  In the second and subsequent iterations of the first iterative process, the selectors 401a and 401b connect the switches to the 1-input contact terminals, and the selectors 401a and 401b receive the peak reduction signals generated by the peak reduction signal generators 407a and 407b as IFFT units. The data is output to the selection units 201a and 201b via 402a and 402b. In the period in which the first iterative process is performed, the selection units 201a and 201b connect the switches to the 0 input contact terminal, and inputs from the IFFT units 402a and 402b are memories 403a and 403b, addition units 404a and 404b, and a selection unit 405a. , 405b. The adders 404a and 404b add the input from the memories 403a and 403b storing the first signal of the first iterative process and the peak reduction signals (outputs of the IFFT units 402a and 402b), and the result is selected by the selector 405a. , 405b.

  In the second and subsequent iterations of the first iterative process, the selectors 405a and 405b connect the switch to the 1-input contact terminal and output the inputs from the adders 404a and 404b to the peak detectors 406a and 406b. This process is repeated, and when the iterative process is completed, the output control unit 408a, 408b outputs to the subsequent stage, the first system is to the phase rotation unit (1) 601 and the phase rotation unit (2) 602, the second system is The signals are input to the phase rotation unit (3) 603 and the phase rotation unit (4) 604. In the phase rotation unit (1) 601 to the phase rotation unit (4) 604, the phase rotation processing is performed so that the correlation coefficient of each system becomes low, and the phase rotation unit (1) 601 and the phase rotation unit (3) 603 Outputs are input to the addition unit 605a, and outputs from the phase rotation unit (2) 602 and the phase rotation unit (4) 604 are input to the addition unit 605b. Adders 605a and 605b synthesize the signals subjected to the phase rotation process and output the results to selectors 201a and 201b.

In the first iteration of the second iterative process, the selectors 201a and 201b connect the switch to the 1-input contact terminal and output the combined signal to the memories 403a and 403b, the adders 404a and 404b, and the selectors 405a and 405b. The memories 403a and 403b store the input from the adding units 605a and 605b only at the first iteration process.
In the first iteration of the second iterative process, the selectors 405a and 405b connect the switch to the 0 input contact terminal and output the combined signal to the peak detectors 406a and 406b and the output controllers 408a and 408b. The output control units 408a and 408b perform control so as not to output to the subsequent stage until the second iterative process is completed. The peak detection units 406a and 406b perform peak detection on the combined signal, and the peak reduction signal generation units 407a and 407b generate peak reduction signals and output the results to the selection units 401a and 401b. The selectors 401a and 401b connect the switch to the 1-input contact terminal during the second iterative process and output a peak reduction signal to the selectors 201a and 201b via the IFFT units 402a and 402b. The selectors 201a and 201b connect the switch to the 0 input contact terminal after the second iteration of the second iterative process, and output a peak reduction signal to the subsequent stage. When the above process is repeated and the iterative process is completed, the data is transmitted from the transmission antennas 409a and 409b via the output control units 408a and 408b and the output control units 202a and 202b.

As described above, according to the second embodiment of the present invention, in the MISO and MIMO multi-carrier transmission system that combines signals of a plurality of transmission systems, in the process of reducing the instantaneous peak that occurs, to the information carrier Interference and out-of-band leakage power can be limited with high accuracy in units of subcarriers, and an increase in bit error rate and a deviation from a spectrum mask can be avoided at the same time.
Further, when the processing speed can be increased, the common circuit can be omitted.

<Embodiment 3>
(Configuration of peak reduction device 3)
Hereinafter, the peak reducing apparatus according to Embodiment 3 of the present invention will be described in detail with reference to FIG.
As shown in FIG. 3, the peak reduction apparatus 3 according to Embodiment 3 of the present invention includes a selection unit 401a, an IFFT unit 402a, a phase rotation unit (1) 601, a selection unit 401b, and an IFFT unit 402b. , Phase rotator (2) 602, adder 605a, memory 403a, adder 404a, selector 405a, peak detector 406a, peak reduction signal generator 407a, output controller 408a, phase A first processing unit including a reverse rotation unit (1) 301, a phase reverse rotation unit (3) 303, and a transmission antenna 409a, a selection unit 401c, an IFFT unit 402c, and a phase rotation unit (3) 603 A selection unit 401d, an IFFT unit 402d, a phase rotation unit (4) 604, an adder 605b, a memory 403b, an addition unit 404b, a selection unit 405b, and a peak detection 406b, a peak reduction signal generating unit 407b, an output control unit 408b, a phase reverse rotation unit (2) 302, a phase reverse rotation unit (4) 304, and a second system processing unit including a transmission antenna 409b; It has.

(Operation and processing of peak reduction device 3)
Next, the operation / processing of the peak reducing apparatus according to the third embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 3, the peak reduction device 3 distributes the frequency domain signals of the first system and the second system, respectively, and inputs the frequency domain signals of the first system to the selection units 401a and 401b. The frequency domain signal is input to the selection units 401c and 401d. The selection units 401a to 401d connect the switch to the 0 input contact terminal in the first iteration, and the output signals of the selection units 401a to 401d are phase rotation units (1) 601 to phase rotation via the IFFT units 402a to 402d. To part (4) 604. The phase rotation unit (1) 601 to the phase rotation unit (4) 604 perform phase rotation processing so that the correlation coefficient of each system becomes low, and the addition units 605a and 605b synthesize those signals.

  The signals synthesized by the addition units 605a and 605b are input to the memories 403a and 403b, the addition units 404a and 404b, and the selection units 405a and 405b. The memories 403a and 403b store the outputs of the adders 605a and 605b only at the first iteration process. Since the switching operation of the selection units 405a and 405b and the processing of the peak detection units 406a and 406b and the peak reduction signal generation units 407a and 407b are the same as those described above, description thereof will be omitted. The peak reduction signals generated by the peak reduction signal generation units 407a and 407b are input to the phase reverse rotation unit (1) 301 to the phase reverse rotation unit (4) 304, and the phase rotation unit (1) 601 to the phase rotation unit ( 4) A rotation process is performed so as to achieve the anti-phase rotation of 604, and the result is fed back to the selection units 401a to 401d.

In the selectors 401a to 401d, the switch after the second iteration of the iterative process is connected to the 1-input contact terminal, subjected to IFFT processing and phase rotation processing, and synthesized by the adders 605a and 605b. The synthesized signals are input to the addition units 404a and 404b, and an addition process with the first signal of the iterative process output from the memories 403a and 403b is performed.
In the second iteration, the selectors 405a and 405b connect the switch to the 1-input contact terminal, and the addition result is output to the subsequent stage. In the subsequent processing, the peak is gradually reduced by repeating the same processing as before. When the iterative process is completed, the peak-reduced signals are output from the output control units 408a and 408b and transmitted from the transmission antennas 409a and 409b.

As described above, according to the third embodiment of the present invention, in the MISO and MIMO multi-carrier transmission system that combines signals of a plurality of transmission systems, in the process of reducing the instantaneous peak that occurs, to the information carrier Interference and out-of-band leakage power can be limited with high accuracy in units of subcarriers, and an increase in bit error rate and a deviation from a spectrum mask can be avoided at the same time.
Further, the circuit scale can be reduced by feeding back the peak reduction processing result to the synthesized signal before the synthesis.

Here, the configuration of the system or apparatus according to the present invention is not necessarily limited to the configuration described above, and various configurations may be used. The present invention can also be provided as, for example, a method or method for executing the processing according to the present invention, a program for realizing such a method or method, or a recording medium for recording the program. It is also possible to provide various systems and devices.
The application field of the present invention is not necessarily limited to the above-described fields, and the present invention can be applied to various fields.
In addition, as various processes performed in the system and apparatus according to the present invention, for example, a computer having hardware resources such as a processor and a memory can store a program permanently stored in a computer-readable recording medium. A configuration that is controlled by execution may be used. In addition, each functional unit for executing the processing may be configured as an independent hardware circuit.

1: peak reduction device, 2: peak reduction device, 3: peak reduction device, 4: peak reduction device, 11: SISO peak reduction unit, 12: SISO peak reduction unit, 101c, 101d: selection unit, 201a, 201b: selection 202a, 202b: output control unit, 301: phase reverse rotation unit (1), 302: phase reverse rotation unit (2), 303: phase reverse rotation unit (3), 304: phase reverse rotation unit (4), 401, 401a, 401b, 401c, 401d: selection unit, 402, 402a, 402b, 402c, 402d: IFFT unit, 403, 403a, 403b, 403c, 403d: memory, 404, 404a, 404b, 404c, 404d: addition unit , 405, 405a, 405b, 405c, 405d: selection unit, 406, 406a, 406b, 406c, 406d Peak detection unit, 407, 407a, 407b, 407c, 407d: peak reduction signal generation unit, 408, 408a, 408b, 408c, 408d: output control unit, 409, 409a, 409b, 409c, 409d: transmission antenna, 601: phase Rotation unit (1), 602: phase rotation unit (2), 603: phase rotation unit (3), 604: phase rotation unit (4), 605a, 605b: addition unit.

Claims (4)

In a MISO (Multiple Input Single Output) communication system having M transmission antennas (M is a natural number) or a MIMO (Multiple Input Multiple Output) communication system, signals of N systems (N is a natural number and N ≦ M) are previously transmitted on the transmission side. In the peak reduction device of the multicarrier transmission device that combines and transmits,
A first IFFT unit that shares a spare carrier to which a peak reduction signal is allocated in each transmission system and converts a frequency domain signal mapped by the OFDM modulation unit in each system into a time domain signal;
A memory for storing a time domain signal converted by the first IFFT unit;
A peak detection unit for detecting a peak value equal to or greater than a predetermined threshold for the time domain signal converted by the first IFFT unit;
Generates a time domain signal that reduces the peak value based on the peak detection result in the peak detection unit, and generates a frequency domain peak reduction signal that increases the specific gravity applied to the spare carrier based on the time domain signal. A peak reduction signal generator that
A second IFFT unit for converting the frequency domain peak reduction signal generated by the peak reduction signal generation unit into a time domain;
A first addition unit that reduces the peak by adding the time domain signal stored in the memory and the time domain peak reduction signal input from the second IFFT unit;
First peak reduction means for gradually reducing the peak each time the number of iterations is increased by repeating the series of processes;
A phase rotation unit that rotates the phase with respect to the time domain signal obtained by the first peak reduction unit;
A second adder that synthesizes N-system signals phase-rotated by the phase rotator;
Second peak reducing means for performing peak reduction similar to the first peak reducing means on the synthesized signal synthesized by the second adder;
A peak reducing apparatus comprising: 2. The peak reduction device according to claim 1, wherein the first peak reduction unit receives the frequency domain signal of a corresponding system, and the second addition unit outputs the synthesized signal based on the frequency domain signal. Output and store the synthesized signal in the memory of the first peak reducing means , and after supplying the synthesized signal to the peak detecting unit, the peak detecting unit, the peak reduced signal generating unit, the second IFFT unit, A peak reduction apparatus characterized in that the configuration of the second peak reduction unit is shared with the first peak reduction unit by sequentially operating the first addition unit . Peak reduction of a multicarrier transmission apparatus that synthesizes and transmits signals of N systems (N is a natural number and N ≦ M) in advance on the transmission side in a MISO or MIMO communication system having M transmission antennas (M is a natural number). In the device
An IFFT unit that shares a spare carrier to which a peak reduction signal is allocated in each transmission system, and converts a frequency domain signal mapped by an OFDM modulation unit in each system into a time domain signal;
A phase rotation unit that rotates the phase with respect to the time domain signal converted by the IFFT unit;
A first adder for synthesizing the time domain signal rotated in phase by the phase rotation unit;
A memory for storing the time domain signal synthesized by the first adder;
A peak detection unit for detecting a peak value equal to or greater than a predetermined threshold with respect to the time domain signal synthesized by the first addition unit;
Generates a time domain signal that reduces the peak value based on the peak detection result in the peak detection unit, and generates a frequency domain peak reduction signal that increases the specific gravity applied to the spare carrier based on the time domain signal. A peak reduction signal generator that
A phase reverse rotation processing unit that performs a reverse rotation process of the phase rotation performed by the phase rotation unit on the frequency domain peak reduction signal generated by the peak reduction signal generation unit;
The IFFT unit converts the frequency domain peak reduction signal input from the phase reverse rotation processing unit into a time domain peak reduction signal, and the converted time domain peak reduction signal is phase rotated by the phase rotation unit. A second addition unit that combines the phase-reduced time-domain peak reduction signal in the first addition unit, and adds the synthesized time-domain peak reduction signal and the time-domain signal stored in the memory;
With
A peak reduction apparatus characterized by gradually reducing the peak every time the number of iterations is increased by repeating the series of processes. In a MISO (Multiple Input Single Output) communication system having M transmission antennas (M is a natural number) or a MIMO (Multiple Input Multiple Output) communication system, signals of N systems (N is a natural number and N ≦ M) are previously transmitted on the transmission side. In the peak reduction method of the multicarrier transmission apparatus that combines and transmits,
A first IFFT processing step for arranging a spare carrier to which a peak reduction signal is allocated in each transmission system in common, and converting a frequency domain signal mapped by an OFDM modulation unit in each system into a time domain signal;
A memory processing step for storing the time domain signal converted in the first IFFT processing step;
A peak detection processing step for detecting a peak value equal to or greater than a predetermined threshold for the time domain signal converted in the first IFFT processing step;
Generate a time domain signal that reduces the peak value based on the peak detection result in the peak detection processing step, and generate a frequency domain peak reduction signal that has a higher specific gravity applied to the spare carrier based on the time domain signal. A peak reduction signal generation processing step to be generated;
A second IFFT processing step of converting the frequency domain peak reduction signal generated in the peak reduction signal generation processing step into a time domain;
A first addition processing step for reducing a peak by adding the time domain signal stored in the memory processing step and the time domain peak reduction signal input in the second IFFT processing step;
A first peak reduction processing step of gradually reducing the peak every time the number of iterations is increased by repeating the series of processes;
A phase rotation processing step for rotating the phase with respect to the time domain signal obtained by the first peak reduction processing step;
A second addition processing step of synthesizing the N system signals rotated in phase in the phase rotation processing step;
A second peak reduction processing step for performing peak reduction similar to the first peak reduction processing step on the synthesized signal synthesized in the second addition processing step;
A peak reducing method characterized by comprising: