JP5199660B2 - Receiver - Google Patents

Description

  The present invention relates to a receiving device constituting a wireless communication device, and more particularly to a receiving device of a wireless communication system to which an OFDM (Orthogonal Frequency Division Multiplexing) scheme is applied.

  For example, as mentioned in Non-Patent Document 1 below, OFDM is a technique for multiplexing and transmitting carriers of a plurality of orthogonal frequencies, and since the allocated frequency band can be used efficiently, This technology is used in many communication fields.

  In a transmission environment where multipath exists due to reflection, etc., multiple reflected waves (delayed waves) with different delays arrive at the receiving end, but in OFDM, a part of the tail of symbol data is copied. Thus, interference between symbols due to delayed waves is eliminated by adding to the head part of the symbol and transmitting. This added repeated portion is called a cyclic prefix (hereinafter referred to as CP).

FIG. 8 is a diagram showing symbols which are data modulation / demodulation units in OFDM. As shown in FIG. 8, in OFDM, a symbol is generated by adding the tail part of the symbol data 101 to be originally transmitted as the CP 102 to the head part. In FIG. 8, “T _S ” is the time length of the symbol data to be originally transmitted, and “T” is the time length including the CP portion.

  FIG. 9 is a diagram showing an example of a state when the symbol shown in FIG. 8 reaches the receiving side with a plurality of reflected waves. In FIG. 9, 110 is a received wave that arrives directly, and 111 and 112 are received waves (delayed waves # 1 and # 2) that arrive with delays of time τ1 and τ2, respectively. At the receiving end, a signal obtained by combining these received waves 110, 111, and 112 is received. As shown in FIG. 9, even when there is a delayed wave, by cutting out the section 113 and executing FFT (Fast Fourier Transform), the FFT for only the component of the symbol that does not include the component of the previous symbol is obtained. Performed, and interference between symbols can be eliminated.

  Thus, in a communication system using OFDM, interference between symbols can be eliminated when the delay time of the delayed wave is within the time range corresponding to CP. Note that the inter-symbol interference suppression technique by CP is also used in SC-FDMA (Single-Carrier Frequency Division Multiple Access) and the like.

Makoto Itami “Fundamentals of OFDM modulation and various technologies for system realization” IEICE Journal Vol.85 No.12 pp.925-931 December 2002

  The FFT input data cut out from the received data on the receiving side is expected to have a waveform that is originally continuous. However, when the frequency deviation and phase noise between the transmitter and the receiver are large, discontinuity occurs at the end of the FFT input data, and this discontinuity in the time domain causes the spectrum to spread in the frequency domain. Then, there is a problem that the spread of the spectrum becomes an interference component to other channels, resulting in a decrease in reception performance.

  In particular, in OFDM, since the frequency use efficiency is increased, the carrier interval is narrow, and it is easily affected by interference components due to frequency deviation and jitter between the transmitter and the receiver.

  The present invention has been made in view of the above, and in a communication system to which OFDM is applied, reception that reduces interference between channels that occurs when there is a frequency deviation or the like and prevents reception performance from being deteriorated. The object is to obtain a device.

  It is another object of the present invention to provide a receiving apparatus that prevents a decrease in receiving performance with a circuit that is easy to implement.

  In order to solve the above-described problems and achieve the object, the present invention performs an information sequence by performing FFT on symbols multiplexed using a plurality of carriers whose information sequences are orthogonal to each other. A data acquisition means for acquiring a continuous received data of a number obtained by adding N (N is an integer) to the number of FFT samples from the received data sequence included in the specific symbol; Filtering means for performing filtering by a window function on the data string obtained by the obtaining means, and the data string from the beginning to the Nth data string after the filtering process, the last of the data string after the filtering process And adding means for generating the same number of FFT target data sequences as the number of FFT samples. That.

  According to the present invention, data exceeding the number of FFT samples is cut out from the data sequence included in each symbol, multiplied by the window function, and then the head portion of the cut data sequence is added to the tail portion. As a result, the same number of data sequences as the number of FFT samples are generated, and the FFT is performed on the generated data sequence. Therefore, the frequency deviation between the transmitter (opposing transmission side communication device) and There is an effect that the discontinuity generated in the FFT input data due to jitter or the like can be alleviated and the error rate characteristic can be prevented from being deteriorated due to the inter-channel interference caused by the discontinuity.

  Embodiments of a receiving apparatus according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a configuration example of a first embodiment of a receiving device according to the present invention, and this receiving device constitutes a communication device of a communication system to which OFDM is applied.

  The receiving apparatus 1 shown in FIG. 1 includes an antenna 11 that receives a signal transmitted from the transmitting side, a band pass filter (BPF: Band Pass Filter) unit 12 that removes frequency components outside the used communication band, A mixer 13 for converting the RF signal output from the BPF unit 12 to a baseband signal, and a local oscillator (LO) that is a local oscillator that determines a frequency when the mixer 13 converts the RF signal to a baseband signal. 14, a low-pass filter (LPF) unit 15 that removes unnecessary frequency components of the received signal converted into baseband, and AD conversion (ADC: Analog Digital) that converts the input analog signal into a digital signal. Converter) section 16 and ADC section 16 detect symbol boundaries for the digital signal data AD-converted. Based on the synchronization control unit 17 that outputs a control signal indicating imming, and the control signal input from the synchronization control unit 17, a portion to be subjected to FFT is cut out from each symbol data, and the cut out data In addition, a cutout control unit 18 that performs a filtering process using a window function, which will be described later, and a partial data addition process for the data output from the cutout control unit 18, and data included in the FFT execution target portion for each symbol A waveform shaping unit 19 that outputs several minutes of data, an FFT (Fast Fourier Transform) unit 20 that converts time-domain data output from the waveform shaping unit 19 into frequency-domain data, and an FFT unit 20 And a demodulator 21 that demodulates the data in the frequency domain according to a prescribed modulation scheme.

  The cutout control unit 18 has a function as a data acquisition unit and a filtering unit, and the waveform shaping unit 19 has a function as an addition unit.

  The symbol is a unit corresponding to the minimum time required for data transmission. In the transceiver, the data to be transmitted is switched for each symbol, and modulation / demodulation processing is performed on a symbol basis.

  Next, the operation of the receiving apparatus 1 will be described focusing on the cutout control unit 18 and the waveform shaping unit 19 that constitute the main part of the present invention.

  A signal transmitted from the communication device (transmitter) on the transmission side is input to the BPF unit 12 via the antenna 11, and after the frequency component outside the use band is removed by the BPF unit 12, the mixer 13 performs baseband processing. The signal is converted into a signal, and unnecessary frequency components are removed by the LPF unit 15. The analog signal output from the LPF unit 15 is converted to digital by the ADC unit 16 and then input to the synchronization control unit 17 and the cutout control unit 18.

  The synchronization control unit 17 detects a symbol boundary of the input digital signal data using a pilot symbol included in the input signal, and outputs a control signal indicating the timing of the symbol boundary to the control unit 18. .

  Based on the signal received from the synchronization control unit 17 (control signal indicating the timing of the symbol boundary of the received signal), the clipping control unit 18 controls the timing at which the input data from the ADC unit 16 is filtered by the window function. The input data and the window function are multiplied. For example, as shown in FIG. 2, the input data is multiplied by the window function shown in the following equation (1) at the timing when the end of the window function becomes equal to the symbol boundary.

That is, i = N _{g to} N _T −1 is extracted from the data series x _i (i = 0 to N _T −1) for each symbol of the signal output from the ADC unit 16, and the above equation (1) is obtained. The calculation shown in the following equation (2) is performed between the discrete series w _j (j = 0 to N _W −1) of the window function sampled at the sampling interval of t _s , and the filtered series y _j (j = 0 to N _W -1) is obtained.

However, N _T is the number of samples of input data in each symbol, and _assuming that the sampling interval is t _s , the relationship of T = N _T · t _S is established. N _W satisfies N _W · t _S = a + T _S , and N _g satisfies N _g + N _W = N _T.

Next, the waveform shaping unit 19 performs the calculation represented by the following equation (3) on the output data series y _j (j = 0 to N _W −1) for each symbol output from the cutout control unit 18. To do. That is, as shown in FIG. 3, a part of the output data series y _j from the cutout control unit 18 is added to obtain a new data series z _k (k = 0 to N _f −1).

However, N _a is assumed to satisfy the relationship of _{N a · t S = a,} N f is a number of samples of the FFT to be executed by the FFT unit 20, and satisfy the relationship of N _f · t _S = T _S .

Then, the FFT unit 20 performs FFT on the time domain data sequence z _k (k = 0 to N _f −1) output from the waveform shaping unit 19 for each symbol, and converts it to a frequency domain data sequence. Then, the demodulator 21 demodulates the data series received from the waveform shaping unit 19 according to a prescribed modulation method.

As described above, in the present embodiment, data larger than the number of FFT samples N _f by N _a is cut from the input data in each symbol, multiplied by the window function, and then the leading _Na sample is terminated. FFT is performed on the data of the total N _f samples obtained by adding to the N _a samples. This alleviates the discontinuity that occurs in the FFT input data due to frequency deviation and jitter with the transmitter (opposite transmission side communication device) and causes interchannel interference caused by the discontinuity. It is possible to prevent the error rate characteristics from deteriorating.

  In constructing a circuit, a circuit for multiplying by a window function and adding a part of data is compared with a conventional configuration in which FFT is performed on a data sequence obtained by simply removing the CP portion. Because of the added configuration, the increase in circuit scale is suppressed and can be easily realized. Further, after the multiplication of the window function, the successful data addition is performed. However, since there is no correlation for noise and there is an effect of averaging, the effect of increasing the SN ratio by basically reducing the noise component can be obtained.

  In the above-described example, a cosine function is used as a part of the window function. However, any condition that satisfies the condition of 1 by adding the tail part of the symbol may be used. For example, as shown in FIG. A similar effect can be obtained by using a simple window function. In addition, it is not always necessary to match the end of the window function to the symbol boundary as in the timing in this example, and the timing for applying the window function within the range that does not cross the symbol boundary of the previous symbol in the delayed wave may be set to the forefront. Good.

Embodiment 2. FIG.
Next, the receiving apparatus according to the second embodiment will be described. In Embodiment 1 described above, an example has been described in which the length of a section in which addition processing is performed in generating a data sequence for performing FFT is fixed length. In the present embodiment, the length of this section is described. An example where the length is variable will be described.

  The CP length necessary to suppress the intersymbol interference component depends on the delay amount of the delayed wave caused by reflection or the like with respect to the direct wave (preceding wave) that has arrived directly from the transmitter. For example, when the delay amount is small, the CP length can be reduced. On the other hand, in the part a in FIG. 2 shown in Embodiment 1 in which the post-filtering addition process using the window function is performed, the longer the part, the higher the effect of averaging and the higher the effect of suppressing interference components. Further, the noise component also has an effect of increasing the suppression effect due to averaging and increasing the S / N ratio. Therefore, in the present embodiment, an example is shown in which the delay amount of the delayed wave is calculated from the received frame (symbol), and the length of the portion a in FIG. 2 is changed according to the delay amount.

  FIG. 5 is a diagram illustrating a configuration example of a receiving apparatus according to the second embodiment. The receiving device 1a shown in FIG. 5 is different from the receiving device 1 shown in Embodiment 1 (see FIG. 1) in place of the cutout control unit 18 and the waveform shaping unit 19 and the cutout shaping unit 18a and the waveform shaping unit. 19a, and a delay measuring unit 31 is added. Since other parts are the same as those of receiving apparatus 1 of the first embodiment, description thereof is omitted.

  In the receiving apparatus 1a according to the present embodiment, the delay measuring unit 31 having a function as a delay amount calculating unit includes an input signal from the ADC unit 16 and an input signal from the FFT unit 20, that is, time domain data of the received frame. Based on the frequency domain data, the delay amount of each delay wave is calculated, and the maximum delay amount is output as the final delay amount.

  The cut-out control unit 18a performs cut-out processing of data to be input data to the FFT unit 20 and filtering by a window function according to the output of the synchronization control unit 17 and the delay amount calculated by the delay measurement unit 31. The waveform shaping unit 19a performs addition processing for the number of samples corresponding to the delay amount calculated by the delay measurement unit 31 on the output of the cutout control unit 18a, and outputs data for the number of FFT input samples in the FFT unit 20. .

Here, the delay amount of the delayed wave which is calculated in the delay measuring section 31 and tau, the number of samples corresponding to tau when the N _d, it is assumed that the relationship τ = N _d · t _s is established. In addition, t _s is the sampling interval.

The clipping control unit 18a of the receiving device 1a outputs data of i = N _{d to} N _T −1 to the data series x _i (i = 0 to N _T −1) for each symbol output from the ADC unit 16. Extraction is performed on the discrete function w _j (j = 0 to N _W2 −1) of the window function and the calculation shown in the following equation (4) is performed, and the filtered sequence y _j (j = 0 to N _W2 −1) is performed. ) N _T is the number of samples of input data in each symbol shown in the first embodiment. As the window function, the “window function that satisfies the condition of adding 1 at the beginning of the symbol and satisfying the condition of 1” shown in the first embodiment is used.

但し、Ｎ_W2は、Ｎ_W2＝Ｎ_T−Ｎ_dの関係を満たすものとする。

However, N _W2 satisfies the relationship N _W2 = N _T −N _d .

The waveform shaping unit 19a executes the addition processing of j j to 0 to N _W2 −N _f −1 and j = N _{f to} N _W2 −1 of y _j , and z _k (k = 0 to N obtained) is obtained. _f- 1) is output to the FFT unit 20. This is the same process as the addition process executed by the waveform shaping unit 19 of the first embodiment, except that the interval in which the addition process is executed is different. N _f is the number of FFT samples shown in the first embodiment.

  As described above, in this embodiment, the interval of calculating the delay amount of the delayed wave that has arrived from the opposite transmission-side communication apparatus (transmitter), changing the number of data samples to be cut out according to the delay amount, and performing the addition process The length of was changed. As a result, interference components can be suppressed without waste. In particular, when the amount of delay is small, the effect of suppressing interference components between channels is enhanced, and the effect of improving the SN ratio is also enhanced.

Embodiment 3 FIG.
Next, the receiving apparatus according to the third embodiment will be described. In the second embodiment described above, an example has been described in which the length of the section in which the addition process is performed in generating the data series for performing the FFT is changed according to the delay amount of the delayed wave. Now, an example will be described in which the length of a section in which addition processing is performed is changed according to the control information held.

  FIG. 6 is a diagram illustrating a configuration example of a receiving apparatus according to the third embodiment. The receiving device 1b shown in FIG. 6 is different from the receiving device 1 shown in Embodiment 1 (see FIG. 1) in place of the cutout control unit 18 and the waveform shaping unit 19, and the cutout shaping unit 18b and the waveform shaping unit. 19b, and an addition section information holding unit 41 is added. Since other parts are the same as those of receiving apparatus 1 of the first embodiment, description thereof is omitted.

  The addition section information holding unit 41 having a function as an information holding unit holds the number of data to be cut out and the time width of the window function as information to be referred to when the cutout control unit 18b performs an operation, and the waveform shaping unit 19B As information to be referred to when performing the operation, information indicating an addition interval of the data series filtered by the cutout control unit 18b (output series from the cutout control unit 18b) is held. Hereinafter, the information held by the addition section information holding unit 41 is collectively referred to as addition section information.

  In the signal reception process by the receiving device 1b according to the present embodiment, the clipping control unit 18b receives the input data to the FFT unit 20 according to the output of the synchronization control unit 17 and the addition section information held in the addition section information holding unit 41. Data to be extracted and a filtering process using a window function. The waveform shaping unit 19b performs addition processing for the number of samples corresponding to the addition interval information held by the addition interval information holding unit 41 with respect to the output of the cutout control unit 18b, and the number of FFT input samples in the FFT unit 20 Output the data.

  The addition section information may be notified to the receiving apparatus as broadcast information when the opposing transmitter is a base station of a wireless communication system, or may be updated by an instruction from an upper layer. It may be. The receiving device executes processing according to the held addition interval information until new addition interval information is notified.

Here, the number of samples corresponding to the addition section indicated by the addition section information held by the addition section information holding unit 41 is N _c .

Cutout control unit 18b of the receiver 1b, to the data series x _i for each symbol output from the ADC unit _{16 (i = 0~N T -1)} , i = N T -N f -N c ~N The data of _T −1 is extracted, the calculation shown in the following equation (5) is performed between the window function discrete series w _j (j = 0 to N _W3 −1), and the filtered series y _j (j = 0 to N _W3 -1) is obtained. N _T is the number of input data samples in each symbol shown in the first embodiment, and N _f is the number of FFT samples shown in the first embodiment. As the window function, the “window function that satisfies the condition of adding 1 at the beginning of the symbol and satisfying the condition of 1” shown in the first embodiment is used.

但し、Ｎ_W3は、Ｎ_W3＝Ｎ_f＋Ｎ_cの関係を満たすものとする。

However, N _W3 satisfies the relationship N _W3 = N _f + N _c .

The waveform shaping unit 19b executes addition processing of j j to 0 to N _W3 −N _f −1 and j = N _{f to} N _W3 −1 of y _j , and z _k (k = 0 to N obtained) is obtained. _f- 1) is output to the FFT unit 20. This is the same process as the addition process executed by the waveform shaping unit 19 of the first embodiment, except that the interval in which the addition process is executed is different. N _f is the number of FFT samples shown in the first embodiment.

  As described above, in the present embodiment, control information (addition section information) indicating a section in which the addition process is performed in the generation process of the data series that is the object of the FFT process is held, and the input data according to the information is stored. Cutout, filtering by window function, and addition processing were performed. As a result, for example, it is possible to perform control such as changing the addition section according to the state of the propagation path, and interference components can be effectively suppressed.

Embodiment 4 FIG.
Next, the receiving apparatus according to the fourth embodiment will be described. In the third embodiment described above, an example in which the addition process is performed for the section indicated by the retained control information has been described. However, in the present embodiment, filtering by a window function and a partial data addition process are performed. A receiving apparatus that can switch between a reception process that accompanies and a reception process that does not involve these will be described.

  FIG. 7 is a diagram illustrating a configuration example of a receiving apparatus according to the fourth embodiment. The receiving device 1c shown in FIG. 7 replaces the receiving device 1 (see FIG. 1) shown in Embodiment 1 in place of the cutting control unit 18, the waveform shaping unit 19, and the FFT unit 20, and a cutting and shaping unit. 18c, the waveform shaping part 19c, and the FFT part 20c, and also the bypass control part 51 is added. Since other parts are the same as those of receiving apparatus 1 of the first embodiment, description thereof is omitted.

  The bypass control unit 51 having a function as a determination unit instructs whether or not to perform filtering processing using a window function and addition processing of partial data in the cutout control unit 18c and the waveform shaping unit 19c.

  In accordance with an instruction from the bypass control unit 51, the cutout control unit 18c cuts out data corresponding to the number of FFT samples in the FFT unit 20c from the output data of the ADC unit 16 and outputs the data to the FFT unit 20c. To do. On the other hand, when filtering processing is performed, data having a larger number of samples than the number of FFT samples in the FFT unit 20c is filtered from the output data of the ADC unit 16 and then output to the waveform shaping unit 19c.

  When the waveform shaping unit 19c receives an instruction to perform waveform shaping from the bypass control unit 51, the waveform shaping unit 19c performs addition processing on a part of the output data of the cutout control unit 18c, and then outputs the result to the FFT unit 20c. In addition, when the data by which the filtering process by the window function was performed are output from the cutting-out control part 18c, an instruction | indication is received from the bypass control part 51 so that waveform shaping may be performed.

  The FFT unit 20c outputs the output data of the waveform shaping unit 19c when the cutout control unit 18c and the waveform shaping unit 19c perform the filtering process by the window function and the addition process of the partial data according to the instruction from the bypass control unit 51. Is selected and the FFT process is executed. On the other hand, when the above process is not performed, the data directly received from the cutout control unit 18c is selected and the FFT process is executed.

  Note that whether or not to perform filtering processing using a window function and addition processing of some data is realized by, for example, a configuration in which control information is included in a received frame. Further, the configuration may be realized in accordance with an instruction from an upper layer.

When the clipping control unit 18c and the waveform shaping unit 19c perform the filtering process by the window function and the addition process of the partial data, the operation is the same as in the case of the first embodiment. On the other hand, when the filtering process by the window function and the addition process of the partial data are not performed, the clipping control unit 18c receives the data series x _i (i = 0 to _NT) after the AD conversion for each symbol received from the ADC unit 16. -1), a data series z _k (k = 0 to N _f −1) obtained by extracting data of i = N _T −N _{f to} N _T −1 is output to the FFT unit 20c. .

  Further, in the present embodiment, the example in which the bypass control unit 51 is added to the receiving device 1 of the first embodiment has been described. However, the receiving device 1a (see FIG. 5) and the implementation of the second embodiment are described. You may make it add the bypass control part 51 with respect to the receiver 1b (refer FIG. 6) of the form 3. For example, when the bypass control unit 51 is added to the receiving device 1a of the second embodiment, the bypass control unit 51 has a maximum value in the delay amount calculated by the delay measurement unit 31 that is smaller than a predetermined value. If a large quality improvement cannot be expected even when the partial data addition process is performed (when the original quality is good), the clipping control unit and the partial data addition process are not performed so that the filtering process by the window function and the partial data addition process are not performed. Controls the waveform shaping unit.

  Further, when combined with the configuration of the third embodiment, the filtering process is not performed until the addition section information is acquired (in a state where the addition section information is not held), and the addition section information is acquired thereafter. Can be configured to perform filtering processing according to the acquired addition interval information.

  As described above, the present embodiment is configured so as to be able to switch whether or not to perform the filtering process by the window function and the addition process of the partial data. Thus, for example, the filtering process is performed only when the frequency deviation between the transmitter and the opposite transmitter is large and the suppression of interference components is necessary. If filtering cannot be performed, filtering operation is not performed, the operation can be changed depending on conditions, such as when filtering processing is not necessary or when sufficient reception quality improvement by filtering processing cannot be expected Can suppress an increase in power consumption and can prevent an increase in processing delay due to filtering.

  As described above, the receiving apparatus according to the present invention is useful for a communication apparatus constituting a wireless communication system. In particular, in a wireless communication system to which an OFDM scheme is applied, reception quality is improved in an environment where multipaths exist. It is suitable for a receiving apparatus that realizes communication in which deterioration is suppressed.

It is a figure which shows the structural example of Embodiment 1 of the receiver concerning this invention. It is a figure which shows an example of the correspondence of a received symbol and a window function. It is a figure which shows an example of the data processing in a waveform shaping part. It is a figure which shows an example of the window function which the receiver concerning this invention uses. It is a figure which shows the structural example of Embodiment 2 of the receiver concerning this invention. It is a figure which shows the structural example of Embodiment 3 of the receiver concerning this invention. It is a figure which shows the structural example of Embodiment 4 of the receiver concerning this invention. It is a figure which shows the symbol which is a data modulation / demodulation unit in OFDM. It is the figure which showed the example of the timing which a some reflected wave arrives at the receiving side in the transmission environment where a multipath exists.

Explanation of symbols

1, 1a, 1b, 1c Receiver 11 Antenna 12 Band pass filter (BPF) part 13 Mixer 14 Local oscillator (LO part)
DESCRIPTION OF SYMBOLS 15 Low pass filter (LPF) part 16 AD conversion (ADC) part 17 Synchronous control part 18, 18a, 18b, 18c Cutout control part 19, 19a, 19b, 19c Waveform shaping part 20, 20c FFT part 21 Demodulation part 31 Delay measurement part 41 Addition section information holding unit 51 Bypass control unit

Claims (4)

A receiving apparatus that restores an information sequence by performing FFT on symbols multiplexed using a plurality of carriers whose information sequences are orthogonal to each other,
A delay amount calculating means for calculating a delay amount of the reflected wave with respect to the direct wave;
A positive integer N, which is a variable value, is determined using the result obtained by dividing the delay amount by the sampling interval, and the number of FFT samples added to the number of FFT samples from the received data sequence included in the specific symbol. Data acquisition means for acquiring received data;
Filtering means for performing filtering by a window function on the data string obtained by the data acquisition means;
The data sequence from the beginning of the data sequence after the filtering process to the Nth data sequence is added to the end including the last data sequence of the data sequence after the filtering process, and the same number of FFT target data sequences as the number of FFT samples Adding means for generating
A receiving apparatus comprising:   The receiving apparatus according to claim 1, wherein the window function is a window function in which an addition result of N sample sections from the beginning of the time width and N sample sections from the end is "1".   The receiving apparatus according to claim 1, wherein the delay amount calculating unit outputs a delay amount of each reflected wave having a maximum value as a final delay amount. further,
Judgment means for judging whether or not to perform reception processing on the continuous reception data of the number obtained by adding the N to the number of FFT samples;
With
The data acquisition means, when the determination means determines that “the reception process for the number of consecutive reception data obtained by adding the N to the number of FFT samples is not performed”, the same number of consecutive receptions as the number of FFT samples Get the data,
Receiving apparatus according to any one of claims 1-3, characterized in that the data sequence obtained with the FFT target data string by said data acquisition means.

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