JP2012191297A - Receiving device, transmitting device, and correction method related to discrete sampling timing of receiving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate errors between a phase and amplitude caused by fraction deviation less than one sample of a DFT window.SOLUTION: A receiving device converting a received time-domain signal into a plurality of frequency-domain signals, has: a discrete Fourier transformation part performing discrete Fourier transformation of a discrete time-domain signal in a discrete Fourier transformation window among discrete time-domain signals obtained by sampling the time-domain signal at a predetermined sampling rate to generate the frequency-domain signals corresponding to a plurality of sub carriers; and a correction part correcting the plurality of frequency-domain signals respectively on the basis of a phase fluctuation amount and an amplitude fluctuation amount that are caused by fraction deviation less than one sample of a discrete Fourier transformation window and depend on a fraction deviation amount and an order of the sub carriers.

Description

  The present invention relates to a receiving apparatus, a transmitting apparatus, and a correction method related to the discrete sample timing.

  In orthogonal frequency division multiplexing (OFDM), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiplexing (SC-OFDM), and single carrier frequency division multiple access (SC-FDMA) schemes, Frequency domain signals that are subcarriers are subjected to inverse discrete Fourier transform (IDFT) to generate time domain signals, up-converted and sent to the communication medium, and the receiving device down-converts the received signals and discretes the time-domain signals. A plurality of frequency domain signals are generated by Fourier transform (DFT), and each signal is demodulated. In SC-OFDM and SC-FDMA, in addition to the above, the transmission apparatus generates a plurality of frequency domain signals by performing discrete Fourier transform on the time domain signal, and the transmission apparatus performs inverse discrete Fourier transform on the plurality of frequency domain signals. One time domain signal is generated.

  A receiving apparatus applied to these communication systems down-converts a received signal to generate a baseband analog signal, which is converted from analog to digital (ADC) to form a digital discrete baseband signal (discrete baseband signal). Signal). Then, discrete Fourier transform is performed on the discrete baseband signal, which is a time domain signal, to generate a frequency domain signal corresponding to a plurality of subcarriers, and a frequency domain signal of each subcarrier is demodulated and decoded. A time domain signal is generated from the frequency domain signal by inverse discrete Fourier transform, and demodulated and decoded.

  In discrete Fourier transform (DFT) including fast Fourier transform (FFT), DFT processing is performed on a discrete baseband signal at a DFT window timing among the discrete baseband signals by a predetermined calculation. It is essential to correctly synchronize the DFT target discrete baseband signal with the DFT window timing. If the DFT target discrete baseband signal is not correctly synchronized with the DFT window timing, the DFT-processed signal may have a large distortion and be correctly demodulated. Can not.

  The DFT window timing synchronization detection method includes a method of detecting DFT window timing based on the timing at which the autocorrelation value is maximized by utilizing the autocorrelation of the guard interval, and a method of detecting consecutive preamble symbols as known symbol patterns. There is a method of taking a correlation value and detecting the DFT window timing based on the timing when the correlation value becomes the largest.

  OFDM, OFDMA, SC-FDMA, and the like are described in the following documents.

  Further, in the OFDMA system and the SC-FDMA system, subcarriers are allocated to a plurality of terminals, so that there is a difference in the timing of transmission signals between the terminals. Therefore, it has been proposed that the transmission timing of a terminal can be adjusted in order to ensure orthogonality of received signals from each terminal. For example, in WiMAX that employs OFDMA, it is standardized to adjust 1/4 sample timing.

JP 2006-197520 A WO 2008/087813 A1

"Fundamentals and Applied Technologies of OFDM Communication Systems" by Trikes, Chapter 3, Reception Synchronization Method of OFDM Communication Systems, P47-51, (ISBN4-88657-235-9)

  Even if the DFT window timing is synchronized by the above method, it is possible to achieve synchronization at the sample point of the discrete baseband signal, but it is not easy to synchronize even a decimal shift of less than one sample of the DFT window timing. For example, even if a DFT window timing shift is detected to less than one sample by the above method, it is difficult to provide a circuit that gives a slight delay to the baseband signal before being sampled by the ADC.

  Therefore, an object of the present invention is to provide a receiving apparatus and a correction method capable of appropriately correcting a received signal even when the DFT window timing has a deviation of less than one sample.

  Another object of the present invention is to provide a receiving apparatus and a correction method for detecting a deviation of less than one sample of DFT window timing.

  Still another object of the present invention is to provide a transmitting apparatus and a correcting method thereof in which a DFT window timing shift of less than one sample does not occur on the receiving apparatus side.

The first aspect of the receiving device is an orthogonal frequency division multiplexing or orthogonal frequency division multiple access receiving device.
A discrete Fourier transform unit that generates a frequency domain signal corresponding to a plurality of subcarriers by performing discrete Fourier transform on a discrete time domain signal within a discrete Fourier transform window among discrete time domain signals obtained by sampling the time domain signal at a predetermined sampling rate. When,
A phase variation amount and an amplitude variation amount due to a fractional shift of less than one sample in the discrete Fourier transform window, based on the phase variation amount and the amplitude variation amount according to the decimal shift amount and the order of the subcarriers. And a correction unit for correcting each of the plurality of frequency domain signals.

  According to the first aspect, it is possible to correct the phase fluctuation amount and the amplitude fluctuation amount due to a deviation (decimal deviation) of less than one sample.

1 is a configuration diagram of an OFDM and OFDMA receiver. FIG. 1 is a configuration diagram of a SC-OFDM and SC-FDMA receiver. It is a figure which shows the example of a relationship between several subcarriers of OFDM, OFDMA, SC-OFDM, and SC-DFMA, and several symbols. It is a figure which shows the determinant of DFT calculation. DFT is a diagram for explaining a rotation factor W ^N arithmetic. Is a diagram showing a Fourier transform (FT) 8 sub-carrier of the signal waveform of the Q components of the frequency domain signals X ₀ to X ₇ after the operation (sin). It is a figure which shows the displacement of the phase and amplitude of a subcarrier by the fractional shift of less than 1 sample. It is another figure which shows the displacement of the phase of a subcarrier by the decimal shift | offset | difference of less than 1 sample, and an amplitude. It is a figure explaining the calculation which calculates | requires the corrected amount in this Embodiment. 1 is a schematic configuration diagram of an OFDM transmitter and receiver. It is a schematic block diagram of the transmitter and receiver of an OFDMA system. It is a block diagram of the OFDM receiver in 1st Embodiment. It is a block diagram of a phase / amplitude correction amount generation unit. FIG. 3 is a configuration diagram of a phase correction unit 17 and an amplitude correction unit 18. It is a figure which shows the structure of the phase rotator and multiplier of a phase correction part and an amplitude correction part. FIG. 2 is a diagram illustrating configurations of a SC-OFDM transmission device and a reception device. 1 is a diagram illustrating a configuration of an SC-FDMA transmission device and a reception device. FIG. 1 is a configuration diagram of a SC-FDMA receiver in a first embodiment. FIG. It is a figure explaining the example of improvement in 1st Embodiment. It is a figure which shows the example of improvement of the OFDM receiver in 1st Embodiment. It is a block diagram of the OFDM receiver in 2nd Embodiment. It is a block diagram of the OFDM receiver in 3rd Embodiment. It is a block diagram of the OFDM receiver in 4th Embodiment. It is a block diagram of the OFDM receiver in 5th Embodiment. It is a block diagram of the OFDM receiver in 6th Embodiment.

  In this embodiment, for example, a transmission device performs inverse discrete Fourier transform on a frequency domain signal that is a plurality of subcarriers to generate a time domain signal, up-converts it, and sends it to a communication medium. The present invention is applied to a communication method in which a time domain signal is converted and a discrete Fourier transform is performed to generate a plurality of frequency domain signals.

  FIG. 1 is a block diagram of an OFDM and SC-OFDM receiver. The receiving apparatus includes a mixer 10 that down-converts a high-frequency received wave Rx received by an antenna using a carrier clock CCLK, and a digital discrete time domain signal obtained by sampling a baseband analog time domain signal S10 in synchronization with a sampling clock SCLK. And an analog-to-digital converter (ADC) 11 for conversion into S11. Further, the receiving device discretely converts the discrete time domain signal S11 in the DFT window according to the DFT timing detection unit 12 that detects the timing of the discrete Fourier transform window of the discrete time domain signal S11 and the DFT window timing signal S12 from the DFT timing detection unit 12. And a DFT unit 13 that performs Fourier transform (DFT) and outputs a frequency domain signal S13 of a plurality of subcarriers. The frequency domain signals S13 of a plurality of subcarriers are demodulated and decoded by the demodulator 14 to generate received data Rxd.

  The receiving apparatus includes an automatic frequency control unit (AFC) 15 that automatically controls the frequency of the carrier clock CCLK based on the phase variation of the pilot signal obtained by demodulating the pilot signal having known data. The frequency error is obtained from the phase change of the plurality of pilot signals, and the frequency of the oscillator OSC1 that generates the carrier clock CCLK is controlled so as to eliminate the frequency error. That is, the signal S15 that the AFC 15 gives to the oscillator OSC1 is a control voltage for controlling the frequency, for example. Further, the AFC 15 controls the frequency of the oscillator OSC2 that generates the sampling clock SCLK in conjunction with the control of the frequency of the carrier clock CCLK. As a result, the sampling rate of the sampling clock SCLK is matched to the cycle of the frequency domain signal S10.

  In this receiving apparatus, the DFT 13 performs a DFT operation on the discrete time domain signal in the DFT window among the discrete time domain signals S11 sampled by the ADC 11, and generates a frequency domain signal S13 for each subcarrier. While the time domain signal S11 is controlled to an appropriate frequency by the AFC 15, the timing of the DFT window of the DFT calculation is controlled to the timing detected by the DFT timing detection unit 12. The DFT timing detection unit 12 detects the optimum timing of the DFT window based on the timing at which the autocorrelation value of the guard interval becomes maximum, the timing at which the correlation value of the preamble synchronization pattern becomes maximum, and the like.

  However, since the DFT timing detector 12 uses the correlation value obtained for the discrete time domain signal S11, the timing accuracy of the DFT window controlled by the correlation value is limited to the accuracy of one sample. , Accuracy of decimal shift less than one sample cannot be obtained. As a result, the DFT window timing is accompanied by a fractional shift of less than one sample (specifically, a shift in the range of 0 to plus or minus 0.5 samples). The phase and amplitude of the frequency domain signal S13 that has been DFT with such a DFT window that has a decimal shift has an error (phase, amplitude displacement) due to the decimal shift.

  FIG. 2 is a block diagram of an OFDMA, SC-FDMA receiver. As in the receiving apparatus of FIG. 1, the mixer 10, ADC 11, DFT timing detector 12, DFT 13, demodulator 14, AFC 15, etc., and a predetermined signal of the frequency domain signal S 13 of a plurality of DFT subcarriers IDFT16 to reverse DFT. The configuration having the IDFT unit 16 is different from the receiving apparatus of FIG.

  Therefore, in the case of OFDMA and SC-FDMA receivers as well, as in OFDM and SC-OFDM receivers, the DFT window timing is shifted by a fraction of one sample, and multiple DFT subcarriers are An error due to a decimal shift occurs in the phase and amplitude of the frequency domain signal S13.

FIG. 3 is a diagram illustrating a relationship example between a plurality of subcarriers of OFDM, OFDMA, SC-OFDM, and SC-DFMA and a plurality of symbols. In this example, a plurality of subcarriers SC _{0 to} SC ₇ are inserted into each of a plurality of symbols S _{m + 1 to} S _{m + 9} , of which pilots are inserted into all subcarriers in symbols S _{m + 2} and S _{m + 8} , and the others Data is modulated on the subcarriers of symbols S _{m + 1} , S _{m + 3 to} S _{m + 7} , and S _{m + 9} .

  The pilot signal is a signal obtained by modulating known data with subcarriers, and the receiving apparatus detects propagation path characteristics, sample point deviation of the DFT window, and the like based on the phase and amplitude of the pilot signal. Further, it is possible to detect a decimal shift of less than one sample to some extent from the above-described correlation value between the preceding and following sample points.

Next, DFT calculation will be described. When the number of points, which is the number of discrete points in the DFT calculation, is N, the DFT (discrete Fourier transform) calculation is performed by performing the following calculation on _N complex number sequences x _{0 to} x _N−1 . it is known that the a calculation for obtaining a complex sequence _X 0 _{~X N-1.}
X _j = Σ (k = 0 to N−1) x _k e ^{{(−2π / N) jk}}
This calculation is also performed in the DFT calculation for converting the time domain signal into the frequency domain signal in the OFDM or OFDMA system. This arithmetic expression can be expressed by the following determinant.

FIG. 4 is a diagram illustrating a determinant of DFT calculation. In FIG. 4A, x _{0 to} x _N−1 are values of sample points _{0 to N−1} of the time domain signal to be DFT-calculated. W ^{0 to} W ^{(N−1) ^ 2} are twiddle factors multiplied by the time domain signals x _{0 to} x _N−1 . Further, X _{0 to} X _N−1 are frequency domain signals obtained by DFT calculation. The frequency domain signals _X 0 _{~X N-1} have different frequencies 0, f, 2f, 3f~ and (N-1) f, the respective phase and amplitude. Note that (N-1) ^ 2 means (N-1) ² .

  That is, in this DFT determinant, the number of points in the DFT window is N points (0 to N-1), and the number of subcarriers (frequency) is N (0 to N-1). The number of points is the number of sample points subject to DFT computation. If there are no oversamples and all sample points are points, all sample points in the DFT window are subject to DFT computation.

FIG. 4B shows an example in which the number of DFT points is N = 8. That is, the frequency domain signals X _{0 to} X ₇ are obtained by multiplying the sampling points x _{0 to} x ₇ of the time domain signal in the DFT window by the twiddle factors W ^{0 to} W ⁴⁹ .

FIG. 5 is a diagram for explaining the twiddle factor W ^N of the DFT calculation. FIG. 5A shows twiddle factors W ^{0 to} W ^N−1 when the number of DFT points is N. Twiddle factors W _N has a phase component which rotates clockwise from W ⁰ angle 0 ° by the angle 2 [pi / N. FIG. 5B shows twiddle factors W ^{0 to} W ⁷ when the number of DFT points is eight. In this case, it has a phase component that rotates clockwise from the angle 0 ° to 45 °.

From the above, it can be understood that the twiddle factors W ^{0 to} W ^N−1 in FIGS. 4 and 5 correspond to e ^{{(−2π / N) jk}} in the above DFT arithmetic expression.

FIG. 6 is a diagram illustrating signal waveforms of eight subcarriers of the Q component (sin) of the frequency domain signals X _{0 to} X ₇ after the Fourier transform (FT) calculation. From this figure, the meaning of the phase of the twiddle factors W ^{0 to} W ^N-1 is understood. Unlike the DFT calculation, the FT calculation is an operation for continuous points. Therefore, as shown in FIG. 6, the frequency domain signals X _{0 to} X ₇ after the FT calculation can be recognized as a waveform composed of continuous points. On the other hand, in the case of the DFT calculation, the calculation is performed on the values at the discrete points of the sample points SP0 to SP8, and the obtained frequency domain signal is also discrete point data.

As shown in this figure, the frequency of each frequency domain signals _X 0 to X ₇ are, _{X 0} is 0 _(DC), since X 1 to X ₇ is a F～7f, the same eight sampling points SP0~SP7 The phase of each subcarrier is different. For example, as shown in FIG.
X ₁ : 0, π / 4, 2π / 4, 3π / 4, 4π / 4, 5π / 4, 6π / 4, 7π / 4
X ₂ : 0, 2π / 4, 4π / 4, 6π / 4, 8π / 4, 10π / 4, 12π / 4, 14π / 4
X ₃ : 0,3π / 4, 6π / 4, 9π / 4, 12π / 4, 15π / 4, 18π / 4, 21π / 4
X ₄ : 0,4π / 4, 8π / 4, 12π / 4, 16π / 4, 20π / 4, 24π / 4, 28π / 4
X ₅ : 0,5π / 4, 10π / 4, 15π / 4, 20π / 4, 25π / 4, 30π / 4, 35π / 4
X ₆ : 0,6π / 4, 12π / 4, 18π / 4, 24π / 4, 30π / 4, 36π / 4, 42π / 4
X ₇ : 0,7π / 4, 14π / 4, 21π / 4, 28π / 4, 35π / 4, 42π / 4, 49π / 4
Thus, since the frequency of each subcarrier has a relationship of 0, f to 7f, the phase at each sampling point is also different. The above phase coincides with the phase components of the twiddle factors W ^{0 to} W ^{49 although} the signs are opposite.

  In FIG. 6, the timing of the DFT window must match the timing of the sample points SP0-SP1, for example. If the timing of the DFT window matches the timing of the sample points SP1 to SP8 delayed by one sample, it means that there is a sample shift in the DFT window. Furthermore, even if the timing of the DFT window is adjusted to the timing of the optimal sample point, if a fractional deviation of less than one sample (0 to ± 0.5 sample deviation) occurs, the phase of the DFT frequency domain signal An error occurs in the amplitude.

FIG. 7 is a diagram showing the subcarrier phase and amplitude displacement due to a fractional shift of less than one sample, as found by experiments by the present inventors. FIG. 7 shows a reference circle RC centered on the origin O on the constellation. If the sampling point is a peak value for all subcarriers are frequency domain signals X ₀ to X ₇ of Figure 6, the signal points of all subcarriers are positioned on the reference circle RC. When a sample point shift (shift by 1 sample unit) occurs in the DFT window, it rotates on the reference circle RC.

  On the other hand, for example, when I and Q of the modulated component are I = -1, Q = -1 (-1 / √2, -1 / √2), if there is no sample shift in the DFT window, the signal point Becomes CD1. If there is a decimal shift of less than one sample in the DFT window, the signal point of each subcarrier is displaced on the displacement circles C1, C2, and C3 indicated by broken lines. In addition, the displacement positions differ depending on the order of the subcarriers, and are arranged on the displacement circles C1, C2, and C3 in the order of the subcarriers. For example, it was found that when the decimal shift amount t is t = 0.5, it is displaced on the displacement circle C2, and the position of the displacement is in the order of subcarriers.

Further, the displacement circles C1, C2, and C3 are inscribed in the reference circle RC. When the radius R of the reference circle is 1, the radius m is smaller than the decimal shift amount t (t = 0 to 1.0).
m = {1-cos (πt)} / 2
Was found by the inventor. That is, the fractional deviation t of the displacement circle C3 having a small radius m is t <0.5, the decimal deviation t of the displacement circle C2 having a radius m = 0.5 is t = 0.5, and the decimal of the displacement circle C1 having a large radius m is t = 0.5. The shift amount t is t> 0.5.

  Further, a plurality of subcarriers (for example, 8 subcarriers SC0 to SC7, the number of 8 points) are sequentially and evenly arranged on the displacement circles C1, C2, and C3, and the subcarrier SC0 having the DC component frequency f0 is a decimal number. Even if a deviation occurs, the signal is located at the signal point CD1 on the reference circle RC, and the subcarriers SC1-SC7 having the frequencies f1-f7 are sequentially and evenly arranged on the displacement circles C1, C2, C3. For example, in the case of the displacement circle C3, the subcarrier SC6 having the frequency f6 has been displaced to the signal point CD2.

  Subcarrier SC6 is at signal point CD1 if there is no decimal point shift, but is displaced to signal point CD2 on displacement circle C3 if there is a decimal shift. That is, when the amplitude is R, it is displaced to an, and when the phase is 5π / 4, it is displaced to 5π / 4-θn. Therefore, in such a case, the amplitude and phase of the signal point CD1 in the state where there is no decimal shift are obtained by multiplying the amplitude of the subcarrier SC6 by R / an and performing amplitude correction and phase correction by rotating the phase by −θn. Can be obtained.

  In this way, even with the same decimal shift amount t, the phase amount varies as shown in FIG. 6 depending on the subcarrier number, and the position on the displacement circle also varies depending on the subcarrier number. The reason for this is not necessarily certain, but it is presumed that the phase and amplitude are displaced by the deviation of the sample point from the peak position of the subcarrier signal due to the fractional deviation of the sample point.

  FIG. 8 is another diagram showing the displacement of the phase and amplitude of the subcarrier due to the decimal shift of less than one sample. In this example, the modulated component of the subcarrier is at the signal point CD11. In this case, if a decimal shift occurs in the DFT window, the subcarrier corresponds to the subcarrier number on the displacement circles C1, C2, and C3. Displace to the position. For example, in the case of the displacement circle C3, the subcarrier SC6 having the frequency f6 is displaced to the signal point CD12. In this case, when the amplitude is R, it is an, and when the phase is 7π / 4, it is 7π / 4-θn. Therefore, also in this case, the amplitude and phase without a decimal shift can be obtained by multiplying the amplitude of the subcarrier SC6 by R / an and performing amplitude correction and phase correction by rotating the phase by −θn.

  This correction amount is the same as in the example of FIG. 7, and the origin O, the signal points CD11 and CD12 shown in FIG. The correction amounts R / an and θn can be obtained from the angle φn. Since the radius m is obtained from the decimal deviation amount t by m = {1-cos (πt)} / 2, it is desirable to obtain the decimal deviation amount t from the above-described correlation value. The rotation angle φn is obtained by equally dividing the displacement circle by the number of subcarriers, and therefore depends on the subcarrier number. Hereinafter, the calculation for obtaining the correction amounts R / an and θn will be described.

  FIG. 9 is a diagram for explaining the calculation for obtaining the correction amount in the present embodiment. FIG. 9 shows an example in which the reception signal point An (In, Qn) of the subcarrier SCn is restored to the original signal point R (Ri, Rq). In this example, the number of subcarriers is 64. In FIG. 9, displacement circles C2 (t = 0.5) and C3 (t <0.5) are shown, and the reference circle is omitted.

  First, it is assumed that the subcarrier SC number n and the decimal shift amount t are known. The radius of the reference circle is R, the amplitude from the origin O of the reception signal point An (In, Qn) of the nth subcarrier SCn is an, the phase rotation amount at the displacement circle C3 is φn, and the fractional deviation t Let mR (m if R = 1) be the radius of the displacement circle obtained from. The phase rotation amount φn is φn = 2π / n, and the distance between the center OX of the displacement circle C3 and the origin O of the constellation is (1-m) R.

Therefore, the amplitude correction amount R / an can be obtained from the received signal point An (In, Qn), the center OX of the displacement circle C3, and the origin O by the cosine theorem as follows.
an ² = (mR) ² + ((1-m) R) ² -2mR (1-mR) cos (π-φn)
= R ² (2m ² -2m + 1 + (2m-2m ² ) cosφn) (1)
Therefore, the following formula is derived.
R / an = 1 / ((2m ² -2m + 1 + (2m-2m ² ) cosφn)) ^1/2 (2)
Next, the following equation can be derived from Stewart's theorem for the triangle consisting of the received signal point An (In, Qn), signal point R (Ri, Rq), and origin O.
(mR) ² = (m an ² + (1-m) x ² ) / (m + (1-m))-(m ((1-m) R) ² + (1-m) (mR) ² ) / (m + (1-m))
= m an ² + (1-m) x ² -mR ² + m ² R ²
as a result,
(1-m) x ² = -m an ² + mR ² (3)
From the equations (1) and (3), the following equation is derived.
x ² = 2m ² an ² (1-cosφn) / (2m ² -2m +1 + (2m-m ² ) cosφn) (4)
When the received signal point An (In, Qn) and the original signal point R (Ri, Rq) of the nth subcarrier SCn are considered as vectors from the origin O, the following equation is derived from the definition of the inner product:
R ・ an = | R | | an | cos θn = (Ri In + Rq Qn) (5)
Furthermore, the following equation is derived from the cosine theorem, and the above equation (5) is substituted as follows.
^{x 2 = R 2 + an 2} - 2R an cos θn
= R ² + an ² -2 (Ri In + Rq Qn) (6)
Substituting R and x in Equations (1) and (4) into Equation (6) and putting them into an equation,
2 (Ri In + Rq Qn) = R ² + an ² -x ²
= 2an ² (1- m + mcosφn) / (2m ² -2m +1 + (2m-m ² ) cosφn) (7)
The following equation is obtained from equations (3) and (5).
| R | | an | cosθn = an ² (1- m + mcosφn) / (2m ² -2m +1 + (2m-m ² ) cosφn) (8)
Substituting equation (2) into equation (8) to make an equation is as follows.
cosθn = (an ² (1- m + mcosφn) / (2m ² -2m +1 + (2m-m ² ) cosφn)) / (| R | | an |)
= (an ² (1-m + mcosφn) / (2m ² -2m + 1 + (2m-m ² ) cosφn)) / (an ² / (2m ² -2m + 1 + (2m-2m ² ) cos ( φn) ^(1/2) )
= ((1-m + mcosφn) / (2m ² -2m + 1 + (2m-m ² ) cosφn)) / (1 / (2m ² -2m + 1 + (2m-2m ² ) cos (φn) ^{( 1/2)} ) (9)
The above equation (2) is the amplitude correction amount, and equation (9) is the phase correction amount, both of which are constants determined by the radius m obtained from the fractional shift amount t and the rotation angle φn obtained from the subcarrier number n. is there. The above calculation results are the same in any of the displacement circles C1, C2, and C3 in FIGS. 7 and 8. When the decimal shift amount t is 0 ≦ t ≦ 1.0, the signal point can be corrected with the same correction amount. is there.

[First Embodiment]
FIG. 10 is a schematic configuration diagram of an OFDM transmission apparatus and reception apparatus. Transmitter MS1 serial-parallel converts transmission data with serial-parallel converter S / P, modulates each with a plurality of subcarriers, and IDFT 34 performs inverse discrete Fourier transform on these frequency-domain signals to generate time-domain signals to generate high-frequency signals. The circuit 36 up-converts and sends it to the communication medium, and the receiving device BS down-converts the received signal by the high-frequency circuit 10, and the time domain signal is subjected to discrete Fourier transform by the DFT 13 to generate a plurality of frequency domain signals. Received data demodulated from a plurality of frequency domain signals is parallel-serial converted.

  FIG. 11 is a schematic configuration diagram of an OFDMA transmission device and a reception device. Unlike FIG. 10, a plurality of transmission devices MS1, MS2 to MSn share frequency domain signals that are a plurality of subcarriers, and transmit data to the reception device BS. Other configurations are the same as those in FIG.

  FIG. 12 is a configuration diagram of an OFDM or OFDMA receiver according to the first embodiment. Similar to the receiving apparatus of FIG. 1, the apparatus includes a mixer 10, an analog-to-digital converter (ADC) 11, a DFT timing detector 12, a DFT 13, a demodulator 14, an AFC 15, and oscillators OSC1 and OSC2. 12 receives the phase / amplitude correction that generates the phase correction amount θn and the amplitude correction amount R / an as the phase fluctuation amount and amplitude fluctuation amount of the frequency domain signal S13 of each subcarrier from the decimal shift amount t. A quantity generation unit 19 is included.

  The phase correction amount θn and the amplitude correction amount R / an are generated for every subcarrier. Further, the OFDM receiver includes a phase correction unit 17 that rotates and corrects the phase of each subcarrier by the phase correction amount θn generated by the phase / amplitude correction amount generation unit 19, and each subcarrier by the amplitude correction amount R / an. And an amplitude correction unit 18 that corrects the amplitude of. The received signal points An (In, Qn) that have been displaced to different positions according to the decimal shift amount t and the subcarrier number by these correction units 17 and 18 are converted into the original signal points R (Ri, Rq). It is corrected to.

  The correction order of the phase correction unit 17 and the amplitude correction unit 18 may be reversed. Further, the decimal shift amount t is obtained by the DFT timing detection unit 12 from the autocorrelation value of the guard interval and the correlation value of the synchronization symbol of the preamble. It is assumed that the DFT timing detection unit 12 matches the timing of the sample point closest to the timing of the most ideal DFT window. However, the deviation of the decimal deviation t (<± 0.5) cannot be adjusted. Note that phase correction and amplitude correction for compensation for the propagation path estimation amount are performed separately from the above correction, but are based on an event independent of the embodiment of the present application. A description of the correction is omitted.

  FIG. 13 is a configuration diagram of the phase / amplitude correction amount generation unit. The phase amplitude correction unit 19 is given a decimal shift amount t, and obtains a radius mR of the displacement circle from the decimal shift amount t by m = {1-cos (πt)} / 2. Then, for each subcarrier SCn (n is in order), the I component and the component m are calculated from the coefficient m of the radius mR of the displacement circle and the cosine value cosφn of the angle φn in the displacement circle. The Q component phase correction amounts cosθn and sinθn and the amplitude correction amount R / an are generated. As shown in FIG. 13, this arithmetic circuit includes an adder (+), a multiplier (×), a subtracter (−), a divider (÷), an inverse number (1 / x), and a square root device (√). , Cos to sin converter 190 and the like.

  Further, the phase / amplitude correction amount generation unit 19 is not an arithmetic circuit as shown in FIG. 13, but the phase correction amount and the amplitude correction amount obtained in advance from the decimal shift amount t and the rotation angle φn of the subcarrier SCn are A table associated with the decimal shift amount t and the subcarrier number n may be recorded on a recording medium and generated by referring to the table.

  FIG. 14 is a configuration diagram of the phase correction unit 17 and the amplitude correction unit 18. The phase correction unit 17 includes phase rotators 17-1 to 17-n that rotate the phase of each of the frequency domain signals S13 of the subcarriers SC1-SCn DFT performed by the DFT 13 by the phase correction amount θn. Furthermore, the amplitude correction unit 18 includes multipliers 18-1 to 18-n that multiply the amplitude-corrected amounts R / a1 to R / an to the signals of the subcarriers that have undergone phase correction. In the configuration of FIG. 14, the frequency domain signals S13 of a plurality of subcarriers are phase-corrected and amplitude-corrected in parallel, but may be serially phase-corrected and amplitude-corrected. Further, phase correction may be performed after amplitude correction.

  FIG. 15 is a diagram illustrating a configuration of a phase rotator and a multiplier of the phase correction unit and the amplitude correction unit. The phase rotator 17-n has four multipliers (×), one adder (+), and one subtractor (+). The phase rotator 17-n receives the I component data and the Q component data of the frequency domain signal, is multiplied by the phase correction amounts cos θn and sin θn, respectively, by four multipliers, and the multiplication value is added. Is added or subtracted by a subtracter and a subtracter.

  The multiplier 18n of the amplitude correction unit multiplies the phase-rotated I component data and Q component data by the amplitude correction amount R / an. As a result, phase and amplitude corrected I and Q component data are generated.

  FIG. 16 is a diagram illustrating the configuration of an OFDMA transmission device and a reception device. In this case, the transmission apparatus which is the mobile station MS1 converts the time domain signal into a frequency domain signal of a plurality of subcarriers by the DFT 30, performs multiplexing by inverse DFT by the IDFT 34, and transmits through the high frequency circuit 36. On the other hand, in the base station BS on the receiving apparatus side, the received signal is down-converted by the high-frequency circuit 10, the DFT 13 performs DFT processing to generate a frequency domain signal of a plurality of subcarriers, and the IDFT 16 performs inverse DFT processing, The transmitted transmission data is generated.

  FIG. 17 is a diagram illustrating a configuration of an SC-FDMA transmission device and a reception device. The SC-FDMA system is expected to suppress the high PAPR in the OFDMA system. In the SC-FDMA wireless communication system, as shown in FIG. 17, each of the mobile stations MS1, MS2 to MSn converts a modulated time domain signal into a frequency domain signal of a plurality of subcarriers by the DFT 30, The modulated component is mapped only to the frequency band assigned to the mobile station, 0 (Null) is mapped to the other frequency band, multiplexed by inverse DFT by the IDFT 34, and transmitted via the high frequency circuit 36 .

  On the other hand, in the base station BS on the receiving apparatus side, the received signal is down-converted by the high-frequency circuit 10, and the DFT 13 performs DFT processing to generate a frequency domain signal of a plurality of subcarriers. The IDFT 16 performs inverse DFT processing for each subcarrier to generate transmission data transmitted by each original mobile station.

  As described above, in SC-OFDMA and SC-FDMA, as in OFDM and OFDMA, a fractional shift of less than one sample in the DFT window occurs, resulting in a shift in the phase and amplitude of the received signal point. Therefore, it is effective to apply the phase correction and amplitude correction described above to SC-OFDM and SC-FDMA receivers.

  FIG. 18 is a configuration diagram of an OFDMA, SC-FDMA receiver in the first embodiment. Similar to the receiving apparatus shown in FIG. 2, this receiving apparatus includes a mixer 10, an analog-digital converter (ADC) 11, a DFT timing detector 12, DFT13, IDFT16, a demodulator 14, AFC15, and oscillators OSC1 and OSC2. . 18 includes a phase and amplitude correction amount generation unit 19 that generates a phase correction amount θn and an amplitude correction amount R / an of each subcarrier based on the decimal shift amount t. The phase correction amount θn and the amplitude correction amount R / an are generated for every subcarrier. Further, the SC-FDMA receiver includes a phase correction unit 17 that rotates and corrects the phase of each subcarrier by the phase correction amount θn generated by the phase / amplitude correction amount generation unit 19 and each amplitude correction amount R / an. And an amplitude correction unit 18 for correcting the amplitude of the subcarrier. The received signal points An (In, Qn) that have been displaced to different positions according to the decimal shift amount t and the subcarrier number by these correction units 17 and 18 are converted into the original signal points R (Ri, Rq). It is corrected to.

  The method for obtaining the phase correction amount θn and the amplitude correction amount R / an from the decimal shift amount t and the subcarrier order n is the same as that in the OFDM and OFDMA receiver described above.

  FIG. 19 is a diagram for explaining an improvement example in the first embodiment. According to the inventor, the received signal point is not the signal point CD2 on the displacement circle C3 described in FIG. 7, but the signal on the adjacent displacement circle C3 ′ separated into two semicircles with the same radius as the displacement circle C3. It becomes point CD2 '. Therefore, in the improved example of the receiving apparatus, in order to perform correction using the phase correction amount and amplitude correction amount obtained on the assumption that the reception signal point is displaced on the displacement circle C3, the reception signal point CD2 ′ is used. Is provided to adjust the signal point CD2 on the displacement circle C3.

  As shown in FIG. 19, on the proximity displacement circle C3 ′, the phase adjustment amount + is applied to the reception signal point CD2 ′ aligned in the clockwise position of the radius (O−CD1) connecting the signal point CD1 and the origin O. The phase is rotated by dθ, and the received signal points arranged in the counterclockwise direction are rotated by the phase adjustment amount −dθ in the opposite direction. After that, it is preferable to perform phase correction and amplitude correction for the above-described displacement circle C3. Since the phase adjustment amount dθ is a minute angle, the same value may be used for all subcarriers. Also, it is preferable to finely adjust the amplitude, but it is acceptable even if it is not finely adjusted because it is very small.

  FIG. 20 is a diagram illustrating an improved example of the OFDM / OFDMA receiver in the first embodiment. Unlike the receiving apparatus of FIG. 12, a phase adjustment unit 20 is provided between the DFT 13 and the demodulation unit 14. The phase adjustment unit 20 is a phase rotator that finely adjusts the phase of each subcarrier by the phase adjustment amount dθ. However, the phase rotator rotates the phase in the positive direction by the phase adjustment amount dθ or the phase in the negative direction according to the order of the subcarriers.

  Providing this phase adjustment unit 20 also in the SC-OFDM and SC-FDMA receivers of FIG. 18 is effective for improving the correction accuracy.

[Second Embodiment]
FIG. 21 is a configuration diagram of an OFDM / OFDMA receiver according to the second embodiment. The receiving apparatus of FIG. 21 includes a plurality of correction units 40 that respectively correct the frequency domain signals of a plurality of subcarriers that have been DFT with phase fluctuation amounts and amplitude fluctuation amounts corresponding to a plurality of decimal shift amounts, and a plurality of correction units 40. Among the corrected frequency domain signals corrected by the correction unit 40, a timing discriminating unit 42 for discriminating a signal having the most likely correction amount, and a frequency domain signal discriminated by the timing discriminating unit 42 to select a subsequent demodulating unit 14 is selected. In FIG. 21, the mixer for down-converting the received signal to baseband, automatic frequency control AFC, and the like are omitted.

  In other words, the plurality of correction units 40 are frequency domain signals of a plurality of subcarriers that have been DFT with a phase variation amount θn and an amplitude variation amount R / an determined in advance corresponding to the decimal shift amount assigned to each. Correct. Then, the timing discriminating unit 42 selects a signal whose phase and amplitude of a known signal such as a pilot signal are closest to the phase and amplitude of the original pilot signal from among the corrected signals output from the plurality of correcting units 40. The selected corrected signal is selected by the selector 44 and output to the demodulator 14 at the subsequent stage.

  The decimal shift amount t of the plurality of correction units 40 is an amount for each predetermined resolution within a range of 0 <t ≦ ± 0.5. For example, +0.5, +0.4, +0.3, +0.2, +0.1, -0.1, -0.2, -0.3, -0.4, -0.5, etc. The phase correction amount and the amplitude correction amount in each correction unit are obtained in advance for each of a plurality of subcarriers by the above-described calculation according to the respective decimal shift amounts t, and are set in the correction unit 40, respectively.

  FIG. 21 shows an example of an OFDM / OFDMA receiver, but the present invention can be similarly applied to an SC-OFDM / SC-FDMA receiver. In the case of the SC-FDMA receiver, an IDFT is provided between the selection unit 44 and the demodulation unit 14.

[Third Embodiment]
FIG. 22 is a configuration diagram of an OFDM / OFDMA receiver according to the third embodiment. The receiving apparatus of FIG. 22 includes a plurality of correction units 40 that respectively correct the frequency domain signals of a plurality of subcarriers that have been DFT with phase fluctuation amounts and amplitude fluctuation amounts corresponding to a plurality of decimal shift amounts, and a plurality of correction units 40. A timing discriminating unit for discriminating a signal having the most likely correction amount among the frequency domain signals after correction corrected by the correction unit; The sampling clock phase control unit 44 generates the sampling clock SCLK by controlling the phase of the master clock MCLK generated by the oscillator OSC2 in accordance with the fractional shift amount t discriminated by the timing discrimination unit 42. In FIG. 22, the mixer for down-converting the received signal to baseband, automatic frequency control AFC, and the like are omitted.

  The plurality of correcting units 40 and the timing discriminating unit 42 are the same as those of the receiving apparatus according to the second embodiment in FIG. On the other hand, in the receiving apparatus of FIG. 22, the sampling clock phase control unit 44 adjusts the phase of the master clock MCLK based on the decimal shift amount t corresponding to the corrected signal discriminated by the timing discriminator 42 and performs sampling. The clock SCLK is generated, and the decimal point deviation of the ADC 11 is zeroed or suppressed. As a result, the decimal shift is set to zero or suppressed in the DFT window detected by the DFT timing detection unit 12 based on the correlation value or the like. Then, the frequency domain signal S13 DFT performed by the DFT 13 is output to the demodulator 14 at the subsequent stage.

  FIG. 22 shows an example of an OFDM / OFDMA receiver, but the present invention can be similarly applied to an SC-OFDM / SC-FDMA receiver. In the case of SC-OFDM and SC-FDMA receivers, an IDFT is provided between the selector 44 and the demodulator 14.

[Fourth Embodiment]
FIG. 23 is a block diagram of an OFDM / OFDMA receiver in the fourth embodiment. The receiving apparatus in FIG. 23 includes a sampling clock phase control unit 44 that controls the phase of the sampling clock SCLK of the ADC 11 according to the decimal shift amount t, as in FIG. And it has the decimal shift | offset | difference amount generation part 50 which produces | generates the decimal shift | offset | difference amount t.

  The decimal shift amount generation unit 50 includes a phase variation amount θn and an amplitude variation amount R / an of a frequency domain signal S13 having known data such as a pilot signal with respect to a frequency domain signal corresponding to the known data when there is no decimal shift. Based on the above, the decimal shift amount t of less than one sample of the DFT window in the DFT 13 is obtained. The calculation by the decimal shift amount generation unit 50 is an inverse calculation of the calculation for obtaining the phase variation amount θn and the amplitude variation amount R / an from the decimal shift amount t described above. Alternatively, the decimal shift amount t may be obtained by referring to a table showing the correspondence between the phase fluctuation amount θn, the amplitude fluctuation amount R / an, and the decimal shift amount t obtained in advance by inverse calculation.

  Note that the phase and amplitude after propagation path compensation are used as the phase and amplitude of the pilot signal. The difference between the phase and amplitude compensated for the propagation path and the phase and amplitude when there is no decimal shift becomes the phase variation amount and the amplitude variation amount.

  Then, the phase control unit 44 adjusts the phase of the master clock MCLK according to the decimal shift amount t obtained by the decimal shift amount generation unit 50 to generate the sampling clock SCLK without decimal shift. As a result, the ADC 11 can generate a discrete time-domain signal at sample points with no decimal deviation.

[Fifth Embodiment]
FIG. 24 is a configuration diagram of an OFDM / OFDMA receiver according to the fifth embodiment. The receiving apparatus in FIG. 24 includes a decimal shift amount generation unit 50 that generates a decimal shift amount t, as in FIG. As described above, the decimal shift amount generation unit 50 obtains the decimal shift amount t from the phase variation amount θn and the amplitude variation amount R / an of the frequency domain signal having known data such as a pilot signal.

  By including the decimal shift amount generation unit 50, the decimal shift amount t can be obtained more accurately. Then, based on the obtained decimal shift amount t, the frequency domain signal DFT performed by the DFT 13 is converted into the phase / amplitude correction amount generation unit 19, the phase correction unit 17 and the amplitude shown in the first embodiment (FIG. 12). The correction unit 18 performs phase correction and frequency correction.

  The pilot signal is not necessarily interpolated in all subcarriers. However, when the decimal shift amount t is detected from the pilot signal built in a certain subcarrier, the phase / amplitude correction amount generation unit 19 detects all the subcarriers. The phase correction amount θn and the amplitude correction amount R / an for the carrier can be obtained. As a result, the phase correction unit 17 and the amplitude correction unit 18 can correct the phase of each subcarrier signal to correct the amplitude.

[Sixth Embodiment]
FIG. 25 is a configuration diagram of an SC-OFDM / SC-FDMA transmission apparatus according to the sixth embodiment. 16 and 17, the basic configuration of a plurality of mobile stations MS and base station BS in the case of SC-OFDM and SC-FDMA systems has been described. As described there, the base station BS receives the received signals transmitted from the plurality of mobile stations MS at the respective timings, performs DFT processing, and further performs IDFT processing. Due to the transmission timing shift of each mobile station MS, the decimal point shift of the DFT window differs for each subcarrier in the receiving apparatus of the base station BS. Therefore, the orthogonality between subcarriers is lost.

  Therefore, the transmission apparatus in the mobile station MS shown in FIG. 24 includes a modulation unit 60 that modulates transmission data Txd, a DFT 61, an IDFT 64, a DAC 65, a mixer 66, an AFC 67, and oscillators OCS11 and OSC12. Thus, a phase correction unit 63 that performs reverse correction in response to a decimal shift at the base station and an amplitude correction unit 62 are provided. Further, the transmitting device calculates the phase correction amount −θn and the amplitude correction amount an / R to be reversely corrected based on the decimal shift amount t with respect to the mobile station MS received by the receiving device 68 of the mobile station MS from the base station BS. A phase / amplitude correction amount generation unit 68 is provided.

  The phase correction amount −θn and the amplitude correction amount an / R to be reversely corrected generated by the phase / amplitude correction amount generation unit 68 are opposite in phase direction to the phase variation amount θn obtained by calculation from the decimal shift amount t described above. Direction, and the amplitude fluctuation amount R / an has a reciprocal relationship.

  The above embodiment is summarized as follows.

(Appendix 1)
In a receiving device for converting a received time domain signal into a plurality of frequency domain signals,
Discrete Fourier transform that generates discrete frequency domain signals corresponding to a plurality of subcarriers by performing discrete Fourier transform on discrete time domain signals within a discrete Fourier transform window among discrete time domain signals obtained by sampling the time domain signal at a predetermined sampling rate. A conversion unit;
A phase variation amount and an amplitude variation amount due to a fractional shift of less than one sample in the discrete Fourier transform window, based on the phase variation amount and the amplitude variation amount according to the decimal shift amount and the order of the subcarriers. , A correction unit that corrects each of the plurality of frequency domain signals.

(Appendix 2)
In Appendix 1,
Further, based on the decimal shift amount and the order of the subcarriers, a first signal point corresponding to the order of the subcarriers on a displacement circle corresponding to the decimal shift amount on the constellation, and the decimal shift And a phase amplitude correction amount generation unit that obtains a phase difference and an amplitude difference from the second signal point when there is no difference as the phase variation amount and the amplitude variation amount.

(Appendix 3)
In Appendix 2,
The receiving device has a radius that is inscribed in a reference circle centered on the origin on the constellation and has a radius corresponding to the decimal shift amount.

(Appendix 4)
In Appendix 3,
The radius m of the displacement circle is m = {1-cos (πt)} / 2 where the radius R of the reference circle is 1 and the amount of decimal shift is t (0 ≦ t ≦ 1). apparatus.

(Appendix 5)
In Appendix 2,
Further, for each of the frequency domain signals of the plurality of subcarriers, the phase difference between the displacement circle and the proximity displacement circle formed by the signal points of the frequency domain signals of the plurality of subcarriers adjacent to the displacement circle when the decimal shift occurs Receiving device having a phase adjustment unit for finely adjusting the frequency.

(Appendix 6)
In Appendix 1 or 2,
Furthermore, the receiving apparatus which has an inverse discrete Fourier-transform part which carries out an inverse discrete Fourier transform of the several frequency domain signal after correction | amendment correct | amended by the said correction | amendment part.

(Appendix 7)
In a receiving device for converting a received time domain signal into a plurality of frequency domain signals,
Discrete Fourier transform that generates discrete frequency domain signals corresponding to a plurality of subcarriers by performing discrete Fourier transform on discrete time domain signals within a discrete Fourier transform window among discrete time domain signals obtained by sampling the time domain signal at a predetermined sampling rate. A conversion unit;
A phase variation amount and an amplitude variation amount that are provided for each of a plurality of decimal shift amount candidates of less than one sample in the discrete Fourier transform window and are caused by the decimal shift amount candidates. A plurality of correction units that respectively correct the plurality of frequency domain signals based on the phase fluctuation amount and the amplitude fluctuation amount according to the carrier order;
A receiving apparatus comprising: a selection unit that selects a plurality of corrected frequency domain signals that are most likely to be corrected among a plurality of corrected frequency domain signals respectively corrected by the plurality of correction units.

(Appendix 8)
In a receiving device for converting a received time domain signal into a plurality of frequency domain signals,
An AD converter that samples the time domain signal in synchronization with a sampling clock to generate a discrete time domain signal;
A discrete Fourier transform unit that performs discrete Fourier transform on the discrete time domain signal within the discrete Fourier transform window of the discrete time domain signal to generate the frequency domain signal corresponding to a plurality of subcarriers;
A phase variation amount and an amplitude variation amount that are provided for each of a plurality of decimal shift amount candidates of less than one sample in the discrete Fourier transform window and are caused by the decimal shift amount candidates. A plurality of correction units that respectively correct the plurality of frequency domain signals based on the phase fluctuation amount and the amplitude fluctuation amount according to the carrier order;
And a sampling clock phase control unit that adjusts the phase of the sampling clock according to the fractional deviation amount of the most probable frequency domain signal corrected by the plurality of correction units.

(Appendix 9)
In Appendix 7 or 8,
The plurality of correction units correspond to the order of the subcarriers on the displacement circle corresponding to the decimal shift amount on the constellation based on the decimal shift amount corresponding to each candidate and the order of the subcarriers. A receiving device that corrects a phase difference and an amplitude difference between a first signal point to be performed and a second signal point when there is no decimal shift as the phase variation amount and the amplitude variation amount.

(Appendix 10)
In Appendix 9,
The receiving device has a radius that is inscribed in a reference circle centered on the origin on the constellation and has a radius corresponding to the decimal shift amount.

(Appendix 11)
In a receiving device for converting a received time domain signal into a plurality of frequency domain signals,
An AD converter that samples the time domain signal in synchronization with a sampling clock to generate a discrete time domain signal;
A discrete Fourier transform unit that performs discrete Fourier transform on the discrete time domain signal within the discrete Fourier transform window of the discrete time domain signal to generate the frequency domain signal corresponding to a plurality of subcarriers;
A fractional deviation of the discrete Fourier transform window of less than one sample based on the phase fluctuation amount and the amplitude fluctuation amount with respect to the frequency domain signal corresponding to the known data when there is no decimal deviation of the frequency domain signal having known data A receiving apparatus including a decimal shift amount generation unit for obtaining the amount;

(Appendix 12)
In Appendix 11,
And a sampling clock phase control unit that adjusts a phase of the sampling clock according to the decimal shift amount obtained by the decimal shift amount generation unit.

(Appendix 13)
In Appendix 11,
Further, the phase fluctuation amount and the amplitude fluctuation amount due to the fractional deviation of less than one sample in the discrete Fourier transform window, and the phase fluctuation amount and the amplitude fluctuation amount according to the decimal deviation amount and the order of the subcarriers. And a correction unit that corrects each of the plurality of frequency domain signals.

(Appendix 14)
In Appendix 11,
The decimal shift amount generation unit obtains a radius of a displacement circle inscribed in a reference circle centered on the origin on the constellation based on a phase difference and an amplitude difference of the frequency domain signal having the known data, and calculates the displacement A receiving device for obtaining the decimal shift amount from a radius of a circle.

(Appendix 15)
Discrete Fourier transform that generates discrete frequency domain signals corresponding to multiple subcarriers by performing discrete Fourier transform on discrete time domain signals within the discrete Fourier transform window of discrete time domain signals obtained by sampling received time domain signals at a predetermined sampling rate In a transmission device that communicates with a reception device having a conversion unit,
An inverse discrete Fourier transform unit for performing inverse discrete Fourier transform on a plurality of frequency domain signals respectively modulated by a plurality of subcarriers;
A phase variation amount and an amplitude variation amount caused by a fractional shift of less than one sample of the discrete Fourier transform window generated in the receiving apparatus, the phase variation amount corresponding to the decimal shift amount and the order of the subcarriers; A transmission apparatus comprising: a correction unit that corrects each of the plurality of frequency domain signals input to the inverse discrete Fourier transform unit based on an amplitude fluctuation amount.

(Appendix 16)
In Appendix 15,
Further, based on the decimal shift amount and the order of the subcarriers, a first signal point corresponding to the order of the subcarriers in a displacement circle corresponding to the decimal shift amount on the constellation and the decimal shift are A transmission apparatus comprising: a phase amplitude correction amount generation unit that obtains a phase difference and an amplitude difference from a second signal point when there is no phase difference as an amount of phase fluctuation and an amount of amplitude fluctuation.

(Appendix 17)
In Appendix 16,
The transmitting device, wherein the displacement circle is inscribed in a reference circle centered on the origin on the constellation and has a radius corresponding to the decimal shift amount.

(Appendix 18)
A receiving device for converting a received time domain signal into a plurality of frequency domain signals,
Discrete Fourier transform that generates discrete frequency domain signals corresponding to a plurality of subcarriers by performing discrete Fourier transform on discrete time domain signals within a discrete Fourier transform window among discrete time domain signals obtained by sampling the time domain signal at a predetermined sampling rate. In a correction method related to discrete sampling timing of a receiving apparatus having a conversion unit,
A phase variation amount and an amplitude variation amount due to a fractional shift of less than one sample in the discrete Fourier transform window, based on the phase variation amount and the amplitude variation amount according to the decimal shift amount and the order of the subcarriers. , A correction method according to discrete sample timing of a receiving apparatus that corrects each of the plurality of frequency domain signals.

10: Mixer 11: ADC
13: DFT (Discrete Fourier Transform unit) 17: Phase correction unit 18: Amplitude correction unit 19: Phase / amplitude correction amount generation unit

Claims (9)

In a receiving device for converting a received time domain signal into a plurality of frequency domain signals,
Discrete Fourier transform that generates discrete frequency domain signals corresponding to a plurality of subcarriers by performing discrete Fourier transform on discrete time domain signals within a discrete Fourier transform window among discrete time domain signals obtained by sampling the time domain signal at a predetermined sampling rate. A conversion unit;
A phase variation amount and an amplitude variation amount due to a fractional shift of less than one sample in the discrete Fourier transform window, based on the phase variation amount and the amplitude variation amount according to the decimal shift amount and the order of the subcarriers. , A correction unit that corrects each of the plurality of frequency domain signals. In claim 1,
Further, based on the decimal shift amount and the order of the subcarriers, a first signal point corresponding to the order of the subcarriers on a displacement circle corresponding to the decimal shift amount on the constellation, and the decimal shift And a phase amplitude correction amount generation unit that obtains a phase difference and an amplitude difference from the second signal point when there is no difference as the phase variation amount and the amplitude variation amount. In claim 2,
The receiving device has a radius that is inscribed in a reference circle centered on the origin on the constellation and has a radius corresponding to the decimal shift amount. In claim 3,
The radius m of the displacement circle is m = {1-cos (πt)} / 2 where the radius R of the reference circle is 1 and the amount of decimal shift is t (0 ≦ t ≦ 1). apparatus. In a receiving device for converting a received time domain signal into a plurality of frequency domain signals,
Discrete Fourier transform that generates discrete frequency domain signals corresponding to a plurality of subcarriers by performing discrete Fourier transform on discrete time domain signals within a discrete Fourier transform window among discrete time domain signals obtained by sampling the time domain signal at a predetermined sampling rate. A conversion unit;
A phase variation amount and an amplitude variation amount that are provided for each of a plurality of decimal shift amount candidates of less than one sample in the discrete Fourier transform window and are caused by the decimal shift amount candidates. A plurality of correction units that respectively correct the plurality of frequency domain signals based on the phase fluctuation amount and the amplitude fluctuation amount according to the carrier order;
A receiving apparatus comprising: a selection unit that selects a plurality of corrected frequency domain signals that are most likely to be corrected among a plurality of corrected frequency domain signals respectively corrected by the plurality of correction units. In a receiving device for converting a received time domain signal into a plurality of frequency domain signals,
An AD converter that samples the time domain signal in synchronization with a sampling clock to generate a discrete time domain signal;
A discrete Fourier transform unit that performs discrete Fourier transform on the discrete time domain signal within the discrete Fourier transform window of the discrete time domain signal to generate the frequency domain signal corresponding to a plurality of subcarriers;
A phase variation amount and an amplitude variation amount that are provided for each of a plurality of decimal shift amount candidates of less than one sample in the discrete Fourier transform window and are caused by the decimal shift amount candidates. A plurality of correction units that respectively correct the plurality of frequency domain signals based on the phase fluctuation amount and the amplitude fluctuation amount according to the carrier order;
And a sampling clock phase control unit that adjusts the phase of the sampling clock according to the fractional deviation amount of the most probable frequency domain signal corrected by the plurality of correction units. In a receiving device for converting a received time domain signal into a plurality of frequency domain signals,
An AD converter that samples the time domain signal in synchronization with a sampling clock to generate a discrete time domain signal;
A discrete Fourier transform unit that performs discrete Fourier transform on the discrete time domain signal within the discrete Fourier transform window of the discrete time domain signal to generate the frequency domain signal corresponding to a plurality of subcarriers;
A fractional deviation of the discrete Fourier transform window of less than one sample based on the phase fluctuation amount and the amplitude fluctuation amount with respect to the frequency domain signal corresponding to the known data when there is no decimal deviation of the frequency domain signal having known data A receiving apparatus including a decimal shift amount generation unit for obtaining the amount; Discrete Fourier transform that generates discrete frequency domain signals corresponding to multiple subcarriers by performing discrete Fourier transform on discrete time domain signals within the discrete Fourier transform window of discrete time domain signals obtained by sampling received time domain signals at a predetermined sampling rate In a transmission device that communicates with a reception device having a conversion unit,
An inverse discrete Fourier transform unit for performing inverse discrete Fourier transform on a plurality of frequency domain signals respectively modulated by a plurality of subcarriers;
A phase variation amount and an amplitude variation amount caused by a fractional shift of less than one sample of the discrete Fourier transform window generated in the receiving apparatus, the phase variation amount corresponding to the decimal shift amount and the order of the subcarriers; A transmission apparatus comprising: a correction unit that corrects each of the plurality of frequency domain signals input to the inverse discrete Fourier transform unit based on an amplitude fluctuation amount. A receiving device for converting a received time domain signal into a plurality of frequency domain signals,
Discrete Fourier transform that generates discrete frequency domain signals corresponding to a plurality of subcarriers by performing discrete Fourier transform on discrete time domain signals within a discrete Fourier transform window among discrete time domain signals obtained by sampling the time domain signal at a predetermined sampling rate. In a correction method related to discrete sampling timing of a receiving apparatus having a conversion unit,
A phase variation amount and an amplitude variation amount due to a fractional shift of less than one sample in the discrete Fourier transform window, based on the phase variation amount and the amplitude variation amount according to the decimal shift amount and the order of the subcarriers. , A correction method according to discrete sample timing of a receiving apparatus that corrects each of the plurality of frequency domain signals.

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