JP5030062B2 - OFDM signal transmitting apparatus, signal processing chip, and OFDM signal transmitting method - Google Patents

Description

  The present invention relates to an OFDM signal transmission apparatus, a signal processing chip, and an OFDM signal transmission method for transmitting or processing an OFDM signal composed of a plurality of subcarriers having orthogonal frequencies.

  In a wireless communication system using Orthogonal Frequency Division Multiplexing (OFDM), the amplitude value is very large compared to the average amplitude value of subcarriers contained in the transmitted OFDM signal due to the characteristics of the transmission amplifier. It is known that a problem that a peak portion has, that is, a problem that a peak power to average power ratio (PAPR) becomes high occurs.

In order to solve such a problem that the PAPR becomes high, a method of repeating clipping and filtering of a peak portion (for example, Patent Document 1), or a Partial Transmit Sequence (PTS) method of transmitting a partial signal sequence having a small peak amplitude value (For example, patent document 2) is proposed.
X. Li and LJ Cimini, “Effects of clipping and filtering on the performance of OFDM”, IEEE Commun. Lett., Vol.2, No.5, pp. 131-133, May 1998 L. J and NR Sollenberger, “Peak-to-Average power ration reduction of an OFDM signal using partial transmit sequences”, IEEE Commun. Lett., Vol.4, No.3, pp. 86-88, March 2000.

  However, the conventional method described above has the following problems. Specifically, in the method of repeating clipping and filtering of the peak portion, it is necessary to execute Fourier transform (FFT) and inverse Fourier transform (IFFT) a plurality of times. Also, in the PTS method, it is necessary to execute IFFT that is multiple times the number of partial signal sequences to be generated. Furthermore, it is necessary to synthesize these partial series signals in various patterns and detect the peak portion.

  That is, the conventional method described above has a problem that the amount of processing necessary to reduce the PAPR increases.

  Therefore, the present invention has been made in view of such a situation, and when OFDM is used, an OFDM signal transmitting apparatus capable of effectively reducing PAPR while suppressing a required processing amount, An object is to provide a signal processing chip and an OFDM signal transmission method.

  In order to solve the problems described above, the present invention has the following features. First, a first feature of the present invention is an OFDM signal transmission apparatus (for example, OFDM signal transmission apparatus 100) that transmits an OFDM signal (OFDM signal S) composed of a plurality of subcarriers having orthogonal frequencies, A peak detection unit (peak detection unit 113) that detects a peak portion (peak portion P1) that is included in the provisional transmission signal (OFDM signal S) and has an amplitude value higher than that of other portions, and an impulse-like signal. A quasi-impulse signal output unit (for example, quasi-impulse signal generation storage unit 115) that outputs a quasi-impulse signal (quasi-impulse signal Ip) and the quasi-impulse signal are detected in the provisional transmission signal by the peak detection unit. The multiplied peak part and the peak part in the quasi-impulse signal are added together so as to cancel each other. A quasi-impulse signal processing unit (quasi-impulse signal processing unit 117) that applies a cyclic shift, and the quasi-impulse signal to which the constant multiple and the cyclic shift are applied by the quasi-impulse signal processing unit as the provisional transmission signal The gist is to include an adding unit (for example, an adding unit 119) for adding.

  According to such an OFDM signal transmitting apparatus, the constant multiple and the cyclic shift are applied so as to cancel each other by adding the peak portion detected in the provisional transmission signal and the peak portion in the quasi-impulse signal. Is done. Further, the quasi-impulse signal to which the constant multiplication and the cyclic shift are applied is added to the provisional transmission signal. For this reason, the said peak part can be reduced, ie, PAPR, can be reduced effectively.

  Also, according to such an OFDM signal transmission apparatus, it is possible to suppress the amount of processing related to Fourier transform or the like rather than a method of repeating clipping and filtering.

  A second feature of the present invention is according to the first feature of the present invention, wherein the quasi-impulse signal output unit executes all of the usable subcarriers as 1 + 0i and performs an inverse Fourier transform of the subcarriers. The essence is to generate the quasi-impulse signal.

  A third feature of the present invention relates to the first feature of the present invention, wherein the quasi-impulse signal output unit outputs a clip having an amplitude other than the peak portion of the tentatively generated quasi-impulse signal, or the peak portion. A process of performing a Fourier transform after multiplying by a constant, a process of adjusting the power of each of the subcarriers so as to satisfy a condition permitted for the quasi-impulse signal, and an inverse Fourier transform of the subcarrier component after the power adjustment The essence is to generate the quasi-impulse signal by a generation process including a process of executing.

  A fourth feature of the present invention relates to the first feature of the present invention, wherein the quasi-impulse signal output unit is configured to provide a quasi-impulse signal other than a peak portion of the quasi-impulse signal with respect to the tentatively generated quasi-impulse signal. The gist of the invention is to generate a quasi-impulse signal by adding the quasi-impulse signal tentatively generated to a signal that has been subjected to phase rotation, cyclic shift, and constant multiplication so that the amplitude of the signal component is reduced. .

  A fifth feature of the present invention relates to the first to fourth features of the present invention, and is summarized in that the quasi-impulse signal output unit generates the quasi-impulse signal by repeating the generation process.

  A sixth feature of the present invention relates to the first to fifth features of the present invention, and is summarized in that the constant multiplication in the quasi-impulse signal processing unit is a constant multiplication by a complex constant.

  A seventh feature of the present invention relates to the sixth feature of the present invention, wherein the quasi-impulse signal output unit includes a quasi-impulse signal having a peak component in an I-phase component and a quasi-impulse having a peak component in a Q-phase component. A signal is generated, and the processing in the quasi-impulse signal processing unit and the adding unit is individually performed on the peak components of the I-phase component and the Q-phase component, and the constant multiple in the quasi-impulse signal is a real constant. The gist is to make it a constant multiple.

  An eighth feature of the present invention is related to the seventh feature of the present invention, wherein a peak portion suppression unit that suppresses the peak portion by clipping the amplitude of the peak portion and filtering the peak portion ( The gist is to further include a clipping / filtering unit 120).

A ninth feature of the present invention is a signal processing chip that executes processing of an OFDM signal composed of a plurality of subcarriers whose frequencies are orthogonal to each other. The signal processing chip is included in the provisional transmission signal, and the amplitude value is compared with other parts. A peak detection unit for detecting a high peak portion, a quasi-impulse signal output unit for outputting a quasi-impulse signal that is an impulse-like signal, and the quasi-impulse signal in the provisional transmission signal by the peak detection unit. A quasi-impulse signal processing unit that applies a constant multiple and a cyclic shift so as to cancel each other by adding the detected peak part and the peak part in the quasi-impulse signal; and the quasi-impulse signal processing unit The quasi-impulse signal to which the constant multiplication and the cyclic shift are applied is added to the provisional transmission signal. And summarized in that and a part.

  A tenth feature of the present invention is an OFDM signal transmission method for transmitting an OFDM signal composed of a plurality of subcarriers having orthogonal frequencies, which is included in the provisional transmission signal and whose amplitude value is compared with other parts. Detecting a high peak portion, outputting a quasi-impulse signal that is an impulse-like signal, the peak portion detected in the provisional transmission signal with respect to the quasi-impulse signal, and the quasi-impulse Applying a constant multiple and a cyclic shift so as to cancel each other by adding a peak portion in the signal, and adding the quasi-impulse signal to which the constant multiple and the cyclic shift are applied to the provisional transmission signal And a step of adding.

  According to the features of the present invention, there are provided an OFDM signal transmitting apparatus, a signal processing chip, and an OFDM signal transmitting method capable of effectively reducing PAPR while suppressing a required processing amount when OFDM is used. be able to.

  Next, an embodiment of the present invention will be described. Specifically, (1) the first embodiment, (2) the second embodiment, (3) the operation and effect, and (4) other embodiments will be described.

  In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones.

  Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(1) First Embodiment In the present embodiment, an OFDM signal transmission apparatus that reduces PAPR by collectively processing OFDM signals including an I-phase component and a Q-phase component will be described.

(1.1) Configuration of OFDM Signal Transmitting Device FIG. 1 is a functional block configuration diagram of an OFDM signal transmitting device 100 according to the present embodiment. Note that the OFDM signal transmitting apparatus 100 is provided as a signal processing chip.

  The OFDM signal transmission apparatus 100 transmits an OFDM signal Sp composed of a plurality of subcarriers having orthogonal frequencies. The OFDM signal Sp has a reduced peak portion included in the OFDM signal S (provisional transmission signal).

  The OFDM signal transmission apparatus 100 includes a symbol mapping unit 101, a control signal generation unit 103, a subcarrier allocation unit 105, an IFFT unit 109, a peak reduction processing unit 110, and an allocation control unit 111.

  The peak reduction processing unit 110 includes a peak detection unit 113, a quasi-impulse signal generation storage unit 115, a quasi-impulse signal processing unit 117, and an addition unit 119.

  Symbol mapping section 101 maps a transmission bit string to an OFDM symbol. Note that the symbol mapping unit 101 uses QAM or PSK as a modulation method.

  The control signal generation unit 103 is a control signal used in the subcarrier allocation unit 105, for example, radio resource allocation information in a radio frame (which mobile station transmits data to which OFDM symbol and subcarrier), The MCS information (modulation scheme and coding rate) used is generated.

  Based on the allocation information output from allocation control section 111, subcarrier allocation section 105 converts the symbol related to the control signal output from control signal generation section 103 and the symbol related to the data signal output from symbol mapping section 101 into an OFDM symbol and Allocated to radio resources to be divided as subcarriers.

  IFFT section 109 receives the OFDM symbol of each subcarrier allocated by subcarrier allocation section 105 as input, and generates a time signal corresponding to the OFDM symbol. In the present embodiment, an OFDM signal S (specifically, refer to FIG. 3) including both the I-phase component and the Q-phase component is output to the peak reduction processing unit 110.

  The peak reduction processing unit 110 executes processing for reducing the peak portion included in the OFDM signal S output from the IFFT unit 109, and outputs the OFDM signal Sp with the peak portion reduced.

  Allocation control section 111 controls subcarrier allocation used in subcarrier allocation section 105.

  Specifically, allocation control section 111 determines whether radio resources divided as OFDM symbols and subcarriers in subcarrier allocation section 105 are used for data transmission such as user data or peak reduction processing. . Allocation control section 111 notifies subcarrier allocation section 105 and quasi-impulse signal generation storage section 115 of subcarriers used for peak reduction processing.

(1.2) Functional Block Configuration of Peak Reduction Processing Unit 110 Next, a functional block configuration of the peak reduction processing unit 110 will be described. As described above, the peak reduction processing unit 110 includes the peak detection unit 113, the quasi-impulse signal generation storage unit 115, the quasi-impulse signal processing unit 117, and the addition unit 119.

The peak detector 113 is included in the OFDM signal S output from the IFFT unit 109 and detects a peak portion having an amplitude value higher than that of other portions. In the present embodiment, the peak detector 113 calculates an amplitude value (I ² + Q ² ) ^0.5 obtained by combining the I-phase component and the Q-phase component, and the magnitude of the amplitude of a signal having an amplitude component larger than a predetermined value. Output the phase and time index.

  The quasi-impulse signal generation storage unit 115 generates a quasi-impulse signal to be added to the OFDM signal S.

  In the present embodiment, the quasi-impulse signal generation storage unit 115 converts the amplitude and phase of the subcarrier used for the peak reduction process notified from the assignment control unit 111, that is, the I-phase component and the Q-phase component to 1 + 0i ( Real part (I-phase component) + imaginary part (Q-phase component)).

  Further, the quasi-impulse signal generation storage unit 115 generates a quasi-impulse signal by performing an inverse Fourier transform of the subcarrier. The quasi-impulse signal generation storage unit 115 outputs a quasi-impulse signal in which the I phase and the Q phase are processed together.

  Specifically, as shown in FIG. 4, the quasi-impulse signal generation storage unit 115 is determined to be used for peak reduction processing by the allocation control unit 111 out of the group G1 and the group G2 configured by a predetermined number of subcarriers. The amplitude and phase of the subcarrier included in the group G2 is set to 1 + 0i, and the inverse Fourier transform of the subcarrier is executed. Note that the subcarriers included in the group G1 are used for data transmission. For this reason, in this embodiment, the impulse-like signal obtained by performing the inverse Fourier transform of the partial subcarrier is called a quasi-impulse signal.

  In the present embodiment, the quasi-impulse signal is dynamically generated every time it is determined according to the subcarrier (resource) conditions determined to be used for the peak reduction process.

  FIG. 5 shows a “time signal” (quasi-impulse signal) after the inverse Fourier transform of the subcarrier is performed. As shown in FIG. 5, the time signal after the inverse Fourier transform of the subcarrier is not necessary in addition to the desired peak portion P1, that is, the peak portion used for suppressing the peak component of the OFDM signal S. A peak portion P2 and a peak portion P3 are also generated.

  The quasi-impulse signal processing unit 117 performs a constant multiplication (in this embodiment, a complex number) and a cycle with respect to the quasi-impulse signal Ip (see FIG. 3) based on the signal component of the peak portion detected by the peak detection unit 113. The click shift is executed, and the quasi-impulse signal Ip on which the processing is executed is output.

  Specifically, the quasi-impulse signal processing unit 117 sets the peak portion detected by P as P, and sets the detected time index as k. That is, it is as (1 type).

P = S (k) (1 formula)
Next, the quasi-impulse signal processing unit 117 converts the OFDM symbol S (t) input from the peak detection unit 113 and the quasi-impulse signal (the peak amplitude is adjusted to 1 and the phase is adjusted to 0) as follows: As it is.

S (t) t: 0 to n-1
I (t) t: 0 to n-1
Further, the quasi-impulse signal processing unit 117 multiplies all quasi-impulse signals by a value represented by (Expression 2).

− | P−Ath | × exp (Arg (P)) (Expression 2)
Here, Ath is a peak reduction target value. Arg (P) is the phase of P. Further, the quasi-impulse signal processing unit 117 cyclically shifts the quasi-impulse signal. The cyclic shift amount given by the quasi-impulse signal processing unit 117 is k, and the quasi-impulse signal after the cyclic shift is expressed by the equation (3) (however, for the multiplication of the equation (2), the equation (3) Not reflected in this).

I ((t + k) mod n) (Expression 3)
The quasi-impulse signal processing unit 117 outputs a quasi-impulse signal subjected to constant multiplication (complex number) and cyclic shift to the adding unit 119.

  The adder 119 adds the quasi-impulse signal Ip output from the quasi-impulse signal processor 117 to the OFDM signal S output from the IFFT unit 109 (see FIG. 3).

  In the present embodiment, the adder 119 adds the quasi-impulse signal Ip obtained by batch processing the I-phase component and the Q-phase component to the OFDM signal S.

(1.3) Operation of OFDM Signal Transmitting Device Next, the operation of the OFDM signal transmitting device 100 will be described. Specifically, an operation in which OFDM signal transmitting apparatus 100 suppresses the peak portion of the OFDM signal using a quasi-impulse signal will be described. FIG. 2 is a diagram illustrating an operation flow in which the OFDM signal transmitting apparatus 100 suppresses the peak portion of the OFDM signal.

  As shown in FIG. 2, in step S10, the OFDM signal transmitting apparatus 100 sets 1 + 0i for the subcarriers used for the peak reduction processing and sets 0 + 0i for the other subcarriers. The OFDM signal transmission apparatus 100 generates a quasi-impulse signal by performing inverse Fourier transform on these data series.

  In step S20, the OFDM signal transmitting apparatus 100 detects a peak portion that is included in the OFDM signal S and has a higher amplitude value than other portions. Note that the processes of step S10 and step S20 may be executed in parallel.

  In step S30, the OFDM signal transmission device 100 executes amplitude control, phase rotation processing, and cyclic shift processing of the generated quasi-impulse signal.

  In step S40, the OFDM signal transmitting apparatus 100 adds the quasi-impulse signal Ip for which the processing has been performed to the OFDM signal S.

(1.4) Modification The quasi-impulse signal generation storage unit 115 may generate a quasi-impulse signal as follows. Alternatively, the quasi-impulse signal generation storage unit 115 may store a signal generated as follows and use the signal.

  The quasi-impulse signal generation storage unit 115 leaves only a desired peak portion for the quasi-impulse signal generated by the above-described method, and adjusts the amplitude, rotates the phase, and cyclically so as to suppress other unnecessary signals. A signal close to the impulse signal is generated by adding the shifted signal to the same (or different) quasi-impulse signal.

  6 performs appropriate amplitude adjustment, phase rotation, and cyclic shift on the time signal shown in FIG. 5 and adds it to the time signal shown in FIG. 5 to obtain a portion other than the desired peak portion (peak portion P1). The time signal after suppressing the unnecessary peak part (peak part P2, P3) is shown.

  In addition, the quasi-impulse signal generation storage unit 115 sets amplitudes other than the peak portion (peak portion P1) of the time signal of the subcarrier as another method for making the tentatively generated peak quasi-impulse signal closer to an impulse shape. Adjustment (multiplication by a value smaller than 1 or setting the amplitude of a signal having an amplitude equal to or greater than a certain value) to perform a Fourier transform. Then, the quasi-impulse signal generation storage unit 115 may set the frequency component that cannot be used as the peak reduction signal to 0, and perform the inverse Fourier transform again.

  Note that the quasi-impulse signal generation storage unit 115 may multiply the peak portion by a constant (> 1) when adjusting the amplitude other than the peak portion.

  The quasi-impulse signal processing unit 117 may repeat the above-described amplitude adjustment, phase rotation, and cyclic shift processing. In the present embodiment, the quasi-impulse signal is dynamically created every time it is determined according to the subcarrier condition determined to be used for the peak reduction process. A sequence corresponding to (for example, a combination of selected subcarriers) may be created in advance, and the created sequence may be stored.

  For example, as shown in FIG. 7, by storing the time waveforms (a) and (b), it is not necessary to perform IFFT for generating the quasi-impulse signal.

  Further, when a plurality of quasi-impulse signals for a sequence divided into predetermined segments are stored, when subcarriers determined to be used for the peak reduction process straddle a plurality of segments, a plurality of quasi-impulse signals for the plurality of segments are stored. What is necessary is just to add an impulse signal.

  Specifically, the time waveform may be stored as shown in FIG. 7, but when the number of segments is large, the combination of all segments becomes the power of the number of segments of 2. For this reason, it is not realistic to store all these time waveforms.

  For example, as shown in FIG. 8, the waveform corresponding to the time waveform shown in Case 3 can be generated by combining the time waveforms (a) and (b) shown in FIG. In other words, a time waveform when only each segment is used is stored, and a quasi-impulse signal for all patterns can be generated by synthesizing time waveforms corresponding to usable segments as necessary. .

(2) Second Embodiment Next, a second embodiment of the present invention will be described. In this embodiment, an OFDM signal transmission apparatus that reduces PAPR by separately processing an I-phase component and a Q-phase component included in an OFDM signal will be described. In the following description, parts different from those of the first embodiment will be mainly described, and description of parts similar to those of the first embodiment will be omitted.

  FIG. 9 is a functional block configuration diagram (part) of the OFDM signal transmitting apparatus 100A according to the present embodiment. As shown in FIG. 9, the OFDM signal transmitting apparatus 100A includes an IFFT unit 109A and a peak reduction processing unit 110A.

  IFFT section 109 </ b> A performs inverse Fourier transform of subcarriers in the same manner as IFFT section 109 of OFDM signal transmission apparatus 100. That is, IFFT section 109A executes the same processing as IFFT section 109, but separates and outputs the I-phase component and Q-phase component of OFDM signal S. In FIG. 7, a dotted line shows an I-phase component, and a solid line shows a Q-phase component.

110 A of peak reduction process parts perform a process independently for every I-phase component and Q-phase component. The processing of the I-phase component is executed by the peak detection unit 113 _I , the quasi-impulse signal generation storage unit 115 _I , the quasi-impulse signal processing unit 117 _I, and the addition unit 119 _I.

The processing of the Q phase component is executed by the peak detection unit 113 _Q , the quasi-impulse signal generation storage unit 115 _Q , the quasi-impulse signal processing unit 117 _Q, and the addition unit 119 _Q.

Subcarrier information and the like are input from the assignment control unit 111 to the quasi-impulse signal generation storage units 115 _I and 155 _Q.

The quasi-impulse signal generation storage unit 115 _I generates an impulse signal having a peak in the + direction of the I-phase component. However, the impulse signal also includes a Q-phase component. This is because only some of the subcarriers are used, so that it is generally impossible to generate a signal sequence (quasi-impulse signal) having an amplitude component other than 0 only in the I-phase component or the Q-phase component.

On the other hand, the quasi-impulse signal generation storage unit 115 _Q generates an impulse signal having a peak in the + direction of the Q-phase component. Similarly, the impulse signal includes an I-phase component.

The quasi-impulse signal processing unit 117 _I outputs an I-phase component to the adding unit 119 _I and outputs a Q-phase component to the adding unit 119 _Q among the quasi-impulse signals output from the quasi-impulse signal generation storage unit 115 _I. .

On the other hand, the quasi-impulse signal processing unit 117 _Q outputs the Q-phase component to the adder 119 _Q and the I-phase component to the adder 119 _I among the quasi-impulse signals output from the quasi-impulse signal generation storage unit 115 _Q. Output.

Specifically, the quasi-impulse signal processing units 117 _I and 117 _Q output quasi-impulse signals obtained by independently processing the I-phase component and the Q-phase component. Specifically, the quasi-impulse signal processing units 117 _I and 117 _Q perform amplitude adjustment of the quasi-impulse signal by scalar calculation. In scalar multiplication, the number of multiplications is ¼ compared to complex multiplication.

As for the I-phase component, a peak portion is detected with respect to the I-phase component of the OFDM signal S generated by the IFFT unit 109A. Information about the detected peak portion is input to the quasi-impulse signal processor 117 _I.

In quasi-impulse signal processor 117 _I, so as to suppress a peak signal corresponding to information about the input peak portion, the cyclic shift and amplitude with respect to the quasi-impulse signal inputted from the quasi-impulse signal generator storage unit 115 _I Adjustment is performed. After the process has been performed, and outputs the I-phase component of the quasi-impulse signal to the adder 119 _I. Also outputs a Q-phase component of the quasi-impulse signal to the adder 119 _Q. The same process is executed for the Q-phase component.

The quasi-impulse signal processing units 117 _I and 117 _Q use both positive and negative values when performing cyclic shift and constant multiplication of the quasi-impulse signals generated by the quasi-impulse signal generation storage units 115I and 115Q. Can do. In addition, by setting the absolute value of the constant to a multiple of 2, it is possible to execute the constant multiple by bit shift on the FPGA / ASIC. Since all peak reduction processing in the present embodiment can be executed without using multiplication, it is considered that the circuit scale of the processing unit necessary for peak reduction can be extremely reduced.

Adders 119 _I and 119 _Q add a quasi-impulse signal obtained by independently processing the I-phase component and the Q-phase component to the OFDM signal. Specifically, the adding unit 119 _I adds the quasi-impulse signal of the I phase component to the I phase component of the OFDM signal output from the IFFT unit 109A. Adding section 119 _Q is the Q-phase component of the output OFDM signals from the IFFT unit 109A, adds the quasi-impulse signal Q phase components.

(3) Operation / Effect According to the OFDM signal transmitting apparatus 100 (100A), the peak portion (for example, the peak portion P1) detected in the OFDM signal S (provisional transmission signal) and the peak portion in the quasi-impulse signal Ip A constant multiple and a cyclic shift are applied so as to cancel each other out by adding. Further, the quasi-impulse signal Ip to which the constant multiplication and the cyclic shift are applied is added to the provisional transmission signal. For this reason, the said peak part can be reduced, ie, PAPR, can be reduced effectively.

  Further, according to the OFDM signal transmitting apparatus 100 (100A), it is possible to suppress the processing amount related to Fourier transform or the like rather than the method of repeating clipping and filtering.

  In the present embodiment, the amplitude and phase of the subcarrier used for peak reduction processing are set to 1 + 0i, and inverse Fourier transform is executed. For this reason, it is possible to easily generate a quasi-impulse signal having only a predetermined frequency component.

  In the present embodiment, the quasi-impulse signal generation storage unit 115 permits the quasi-impulse signal Ip to perform a clip having an amplitude other than the peak portion of the quasi-impulse signal Ip, or to perform a Fourier transform after multiplying the peak portion by a constant. A generation process including a process of adjusting the power of each subcarrier so as to satisfy the above conditions and a process of performing an inverse Fourier transform of the subcarrier is executed. Further, the quasi-impulse signal Ip is generated by repeating the process a predetermined number of times.

  Further, the quasi-impulse signal generation storage unit 115 temporarily generates a quasi-impulse signal generated by performing phase rotation, cyclic shift, and constant multiplication so that the amplitude of signal components other than the peak portion of the quasi-impulse signal Ip is reduced. A quasi-impulse signal Ip is generated by adding the impulse signals. For this reason, the said peak part can be reduced more effectively.

(4) Other Embodiments As described above, the contents of the present invention have been disclosed through the first and second embodiments of the present invention. However, the description and the drawings that constitute a part of this disclosure limit the present invention. Should not be understood. From this disclosure, various alternative embodiments will be apparent to those skilled in the art.

  For example, the OFDM signal transmitting apparatus 100 according to the first embodiment described above may be added with a function of performing clipping of the amplitude of the peak portion and filtering.

  Specifically, as shown in FIG. 10A, the OFDM signal transmitting apparatus 100 can add a clipping / filtering unit 120 similar to the conventional one to the subsequent stage of the peak reduction processing unit 110.

  Further, as shown in FIG. 10B, an OFDM signal generation unit 107 using a Partial Transmit Sequence (PTS) for transmitting a partial signal sequence having a small peak amplitude value is added to the OFDM signal transmitting apparatus 100. Also good.

  Furthermore, in the first and second embodiments described above, the amplitude other than the peak portion of the subcarrier time signal used for the peak reduction processing is adjusted, inverse Fourier transform is executed, or the peak portion is multiplied by a constant. However, this process does not necessarily have to be executed.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

It is a functional block block diagram of the OFDM signal transmission apparatus 100 which concerns on 1st Embodiment of this invention. It is a figure which shows the operation | movement flow in which the OFDM signal transmitter 100 which concerns on 1st Embodiment of this invention suppresses the peak part of an OFDM signal. It is a figure which shows the signal example of OFDM signal S and quasi-impulse signal Ip which concern on 1st Embodiment of this invention. It is a figure which shows the relationship between the group of the subcarrier used for the peak reduction process in 1st Embodiment of this invention, and the amplitude of the said subcarrier. It is a figure which shows the time signal after performing the inverse Fourier transform of the subcarrier which concerns on 1st Embodiment of this invention. It is a figure which shows the time signal after suppressing the unnecessary peak part other than the desired peak part by adding the signal which performed the rotation and cyclic shift of an appropriate phase to the time signal shown in FIG. It is explanatory drawing of the production | generation method of the semi-impulse signal which concerns on the example of a change which concerns on 1st Embodiment of this invention. It is explanatory drawing of the production | generation method of the semi-impulse signal which concerns on the example of a change which concerns on 1st Embodiment of this invention. It is a functional block block diagram (part) of OFDM signal transmitter 100A which concerns on 2nd Embodiment of this invention. It is a functional block block diagram (part) of the OFDM signal transmitter which concerns on the modification of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100,100A ... OFDM signal transmission apparatus, 101 ... Symbol mapping part, 103 ... Control signal generation part, 105 ... Subcarrier allocation part, 107 ... OFDM signal generation part, 109, 109A ... IFFT part, 110, 110A ... Peak reduction process 111, assignment control unit, 113, 113 _I , 113 _Q ... peak detection unit, 115, 115 _I , 115 _Q ... quasi-impulse signal generation storage unit, 117, 117 _I , 117 _Q ... quasi-impulse signal processing unit, 119 , 119 _I , 119 _Q ... adder, 120 ... clipping and filtering unit, G1, G2 ... group, P1 to P3 ... peak part, S, Sp ... OFDM signal, I, Ip ... quasi-impulse signal

Claims (11)

An OFDM signal transmitting apparatus that transmits an OFDM signal composed of a plurality of subcarriers having orthogonal frequencies,
A peak detection unit that is included in the provisional transmission signal and detects a peak portion having an amplitude value higher than that of other portions;
A quasi-impulse signal output section for outputting a quasi-impulse signal which is an impulse-like signal;
With respect to the quasi-impulse signal, the peak portion detected in the provisional transmission signal by the peak detection unit and the peak portion in the quasi-impulse signal are added to each other so as to cancel each other. A quasi-impulse signal processor for applying click shift;
An addition unit that adds the quasi-impulse signal to which the constant multiple and the cyclic shift are applied by the quasi-impulse signal processing unit to the provisional transmission signal;
The quasi-impulse signal output unit is
Clip of amplitude other than the peak portion of the quasi-impulse signal generated temporarily, or processing to execute Fourier transform after multiplying the peak portion by a constant,
A process of adjusting the power of each of the subcarriers so as to satisfy the conditions allowed for the quasi-impulse signal;
An OFDM signal transmitting apparatus that generates the quasi-impulse signal by a generation process including a process of performing an inverse Fourier transform of the subcarrier component after the power adjustment. An OFDM signal transmitting apparatus that transmits an OFDM signal composed of a plurality of subcarriers having orthogonal frequencies,
A peak detection unit that is included in the provisional transmission signal and detects a peak portion having an amplitude value higher than that of other portions;
A quasi-impulse signal output section for outputting a quasi-impulse signal which is an impulse-like signal;
With respect to the quasi-impulse signal, the peak portion detected in the provisional transmission signal by the peak detection unit and the peak portion in the quasi-impulse signal are added to each other so as to cancel each other. A quasi-impulse signal processor for applying click shift;
An addition unit that adds the quasi-impulse signal to which the constant multiple and the cyclic shift are applied by the quasi-impulse signal processing unit to the provisional transmission signal;
The quasi-impulse signal output unit performs phase rotation, cyclic shift, and constant multiplication so as to reduce the amplitude of signal components other than the peak portion of the quasi-impulse signal with respect to the tentatively generated quasi-impulse signal. An OFDM signal transmitting apparatus that generates a quasi-impulse signal by adding the tentatively generated quasi-impulse signal to an executed signal. 3. The OFDM signal according to claim 1 , wherein the quasi-impulse signal output unit generates the quasi-impulse signal by performing an inverse Fourier transform of the subcarriers with all usable subcarriers being 1 + 0i. Transmitter device. The OFDM signal transmission device according to claim 1 , wherein the quasi-impulse signal output unit generates the quasi-impulse signal by repeating the generation process.   5. The OFDM signal transmission apparatus according to claim 1, wherein the constant multiple in the quasi-impulse signal processing unit is a constant multiple by a complex constant. The quasi-impulse signal output unit generates a quasi-impulse signal having a peak component in the I-phase component and a quasi-impulse signal having a peak component in the Q-phase component,
The processes in the quasi-impulse signal processing unit and the adding unit are individually performed on the peak components of the I-phase component and the Q-phase component,
6. The OFDM signal transmission apparatus according to claim 5, wherein the constant multiple in the quasi-impulse signal is a constant multiple based on a real constant.   The OFDM signal transmitting apparatus according to claim 6, further comprising: a peak part suppressing unit that suppresses the peak part by performing clipping of the amplitude of the peak part and filtering of the peak part. A signal processing chip that executes processing of an OFDM signal composed of a plurality of subcarriers having orthogonal frequencies,
A peak detection unit that is included in the provisional transmission signal and detects a peak portion having an amplitude value higher than that of other portions;
A quasi-impulse signal output section for outputting a quasi-impulse signal which is an impulse-like signal;
With respect to the quasi-impulse signal, the peak portion detected in the provisional transmission signal by the peak detection unit and the peak portion in the quasi-impulse signal are added to each other so as to cancel each other. A quasi-impulse signal processor for applying click shift;
An addition unit that adds the quasi-impulse signal to which the constant multiple and the cyclic shift are applied by the quasi-impulse signal processing unit to the provisional transmission signal;
The quasi-impulse signal output unit is
Clip of amplitude other than the peak portion of the quasi-impulse signal generated temporarily, or processing to execute Fourier transform after multiplying the peak portion by a constant,
A process of adjusting the power of each of the subcarriers so as to satisfy the conditions allowed for the quasi-impulse signal;
A signal processing chip that generates the quasi-impulse signal by a generation process including a process of performing an inverse Fourier transform of the subcarrier component after the power adjustment. A signal processing chip that executes processing of an OFDM signal composed of a plurality of subcarriers having orthogonal frequencies,
A peak detection unit that is included in the provisional transmission signal and detects a peak portion having an amplitude value higher than that of other portions;
A quasi-impulse signal output section for outputting a quasi-impulse signal which is an impulse-like signal;
With respect to the quasi-impulse signal, the peak portion detected in the provisional transmission signal by the peak detection unit and the peak portion in the quasi-impulse signal are added to each other so as to cancel each other. A quasi-impulse signal processor for applying click shift;
An addition unit that adds the quasi-impulse signal to which the constant multiple and the cyclic shift are applied by the quasi-impulse signal processing unit to the provisional transmission signal;
The quasi-impulse signal output unit performs phase rotation, cyclic shift, and constant multiplication so as to reduce the amplitude of signal components other than the peak portion of the quasi-impulse signal with respect to the tentatively generated quasi-impulse signal. A signal processing chip that generates a quasi-impulse signal by adding the tentatively generated quasi-impulse signal to an executed signal. An OFDM signal transmission method for transmitting an OFDM signal composed of a plurality of subcarriers having orthogonal frequencies,
A step of detecting a peak portion included in the provisional transmission signal and having an amplitude value higher than that of other portions;
Outputting a quasi-impulse signal which is an impulse signal;
A constant multiple and a cyclic shift are applied to the quasi-impulse signal so as to cancel each other by adding the peak portion detected in the provisional transmission signal and the peak portion in the quasi-impulse signal. Steps,
Adding the quasi-impulse signal to which the constant multiple and the cyclic shift are applied to the provisional transmission signal,
In the step of outputting the quasi-impulse signal,
Clip of amplitude other than the peak portion of the quasi-impulse signal generated temporarily, or processing to execute Fourier transform after multiplying the peak portion by a constant,
A process of adjusting the power of each of the subcarriers so as to satisfy the conditions allowed for the quasi-impulse signal;
An OFDM signal transmission method for generating the quasi-impulse signal by a generation process including a process of performing an inverse Fourier transform of the subcarrier component after the power adjustment. An OFDM signal transmission method for transmitting an OFDM signal composed of a plurality of subcarriers having orthogonal frequencies,
A step of detecting a peak portion included in the provisional transmission signal and having an amplitude value higher than that of other portions;
Outputting a quasi-impulse signal which is an impulse signal;
A constant multiple and a cyclic shift are applied to the quasi-impulse signal so as to cancel each other by adding the peak portion detected in the provisional transmission signal and the peak portion in the quasi-impulse signal. Steps,
Adding the quasi-impulse signal to which the constant multiple and the cyclic shift are applied to the provisional transmission signal,
In the step of outputting the quasi-impulse signal, a phase rotation, a cyclic shift, and a constant are set so that the amplitude of a signal component other than the peak portion of the quasi-impulse signal is reduced with respect to the tentatively generated quasi-impulse signal. An OFDM signal transmitting method for generating a quasi-impulse signal by adding the tentatively generated quasi-impulse signal to a signal subjected to multiplication.

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