JP5530238B2 - Receiving apparatus and receiving method - Google Patents

Description

  The present invention relates to a receiving apparatus and a receiving method for receiving and demodulating a digital modulation signal compliant with the OFDM system.

  For example, in OFDM communication performed via an aerial transmission line such as terrestrial digital broadcasting, a guard interval is provided for each symbol as a countermeasure against multipath. This guard interval is arranged so that a portion located at the end of the original effective symbol section is copied to the start end of the symbol. For this reason, the signal received by the receiving apparatus has a configuration in which a large number of transmission symbol sections including a guard interval section and an effective symbol section are continuous.

  In this case, in the FFT processing, it is necessary to extract only a signal portion having an effective symbol period length in one transmission symbol period. In addition, in the received signal on which the delayed wave is superimposed, it is necessary to perform the above extraction at a timing at which intersymbol interference caused by transmission symbols positioned before and after is minimized.

  As described above, for example, a method described in Patent Document 1 has been proposed as one of methods for extracting a signal having an effective symbol interval length for FFT processing at a timing that suppresses intersymbol interference as much as possible from an OFDM received signal. In this conventional technique, it is assumed that a signal for FFT processing is extracted using a first timing signal generated by guard interval correlation in time domain processing before FFT processing. On the other hand, the delay profile is estimated based on the transmission path characteristics calculated from the pilot signal in the frequency domain processing after the FFT processing. Then, the first timing signal is offset by the timing offset adjustment signal generated based on the delay profile. This optimizes the signal extraction timing.

Japanese Patent No. 3654646

  As described above, in the method of obtaining the extraction timing for extracting the FFT processing signal from the delay profile, it is known that the obtained extraction timing is more accurate than the extraction timing obtained from the guard interval correlation. Yes. Therefore, it is desirable to use the extraction timing obtained from the delay profile as much as possible. However, the influence of aliasing, which is a folding signal, is inevitable on the delay profile. Extraction timings corresponding to the number of aliases are detected from the delay profile in which aliasing has occurred. For this reason, a means for selecting which extraction timing is the optimum extraction timing is required. In addition, when the delay time of the delayed wave is large, the extraction timing obtained from the delay profile is likely to deviate greatly from the optimum extraction timing, and means for determining whether the extraction timing obtained from the delay profile is appropriate is necessary. . In addition, a means for inappropriate cases is also necessary.

  As described above, the conventional technique does not have a function that can simultaneously select the extraction timing obtained from the delay profile, determine the appropriateness, and handle the case where it is not appropriate, resulting in accurate window position control. I couldn't do it well.

  The problem to be solved by the present invention includes the above-described problem as an example.

In order to solve the above problems, the invention according to claim 1 is characterized in that time domain processing means for performing time domain processing on an OFDM signal received from an antenna and outputting an IQ demodulated signal, and a window position for the IQ demodulated signal. Window extraction means for extracting a window based on a control signal, FFT processing means for performing FFT processing on the IQ demodulated signal window extracted by the window extracting means, and calculating a guard interval correlation from the IQ demodulated signal GI correlation calculation means, GI ISI distribution calculation means for calculating a GI ISI distribution based on the guard interval correlation, and transmission path characteristics for calculating a transmission path characteristic echo profile from the signal FFT processed by the FFT processing means EP-based ISI distribution for calculating an EP-based ISI distribution based on an EP calculating means and the transmission path characteristic echo profile Output means, EP system window position information detection means for detecting at least one or more EP system window position information based on the EP system ISI distribution, and the GI system ISI distribution and the EP system window position information based on the EP system window position information. A window position determination control unit that generates a window position control signal and outputs the window position control signal to the window extraction unit. The window position determination control unit uses the GI system ISI distribution, and the EP system window position information detection unit. Generating at least one EP system window position information selection means for selecting one of the detected EP system window position information, and generating the window position control signal corresponding to the selected EP system window position information. Window position control means for outputting to the window extraction means, and the EP window position information includes an EP system extraction timing indicating a time when the EP system ISI distribution reaches a maximum value. window The position information selection means calculates the AISI power of the GI system ISI distribution at the EP system extraction timing, and selects the EP system window position information that maximizes the AISI power among the calculated at least one AISI power. .

In order to solve the above-mentioned problems, a third aspect of the present invention provides a time-domain processing step of outputting an IQ demodulated signal by performing time-domain processing on an OFDM signal received from an antenna, and a window position for the IQ demodulated signal. A window extraction step for performing window extraction based on the control signal, an FFT processing step for performing FFT processing on the IQ demodulated signal window extracted by the window extraction step, and calculating a guard interval correlation from the IQ demodulated signal A GI correlation calculating step, a GI ISI distribution calculating step for calculating a GI ISI distribution based on the guard interval correlation, and a transmission channel characteristic for calculating a transmission channel characteristic echo profile from the signal subjected to the FFT processing in the FFT processing step. EP-based IS based on the EP calculation step and the transmission path characteristic echo profile EP system ISI distribution calculating step for calculating distribution, EP system window position information detecting step for detecting at least one or more EP system window position information based on the EP system ISI distribution, GI system ISI distribution and EP A window position determination control step for generating the window position control signal based on the system window position information and outputting the window position control signal to the window extraction step; and the window position determination control step using the GI system ISI distribution, the EP system window An EP window position information selection step for selecting one of the at least one EP window position information detected by the position information detection step, and the window position control corresponding to the selected EP window position information. A window position control step that generates a signal and outputs the signal to the window extraction step, and the EP window position information is a maximum value in the EP ISI distribution. The EP system window position information selection step calculates an AISI power of the GI system ISI distribution at the EP system extraction timing, and calculates at least one calculated AISI power. The EP system window position information that maximizes the AISI power is selected.

It is a block diagram which shows the structural example of the receiver in embodiment of this invention. It is a figure which shows the data structural example of the transmission symbol in IQ demodulated signal. It is a figure explaining an ISI distribution and its basic way of obtaining. FIG. 2 is a block diagram illustrating a detailed configuration example of a GI correlation calculation unit and a GI system ISI distribution calculation unit illustrated in FIG. 1. It is a figure showing the process of the change of the signal until it produces | generates GI type | system | group ISI distribution from an IQ demodulation signal in the case of 1 multipath wave. It is a figure showing the process of the change of the signal until it produces | generates GI type | system | group ISI distribution from an IQ demodulated signal in the case of 2 multipath waves. FIG. 2 is a block diagram illustrating a detailed configuration example of a transmission path characteristic EP calculation unit, an EP system ISI distribution calculation unit, and an EP system window position information detection unit illustrated in FIG. 1. It is a figure showing an example of the process of calculating EP system window position information by the transmission path characteristic EP calculation part, EP system ISI distribution calculation part, and EP system window position information detection part in the case of multipath 2 waves. It is a figure explaining the interference of the transmission path characteristics EP by aliasing. It is a block diagram which shows the detailed structural example and its function of the window position determination control part in embodiment of this invention shown in FIG. It is a block diagram which shows the structural example of the receiver in a 1st modification. FIG. 12 is a block diagram illustrating a detailed configuration example of a GI correlation calculation unit, a GI system ISI distribution calculation unit, and a GI system window position information detection unit illustrated in FIG. 11. It is a block diagram which shows the detailed structural example of the window position determination part shown in FIG. 11, and its function. It is a figure which shows an example of the relationship between the time function of GI system extraction timing, GI system peak value, GI system ISI distribution, and optimal extraction timing.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram illustrating a configuration example of a receiving device according to an embodiment of the present invention.

  The receiving apparatus 100 mainly includes an antenna 1, a time domain processing unit 2, a window extraction unit 3, an FFT processing unit 4, a GI correlation calculation unit 5, a GI system ISI distribution calculation unit 6, and transmission path characteristics. An EP calculation unit 8, an EP system ISI distribution calculation unit 9, an EP system window position information detection unit 10, and a window position determination control unit 13 are included.

  In addition, the arrow which shows the flow of the signal in a figure shows the flow of the main signal between each component, For example, regarding signals, such as a response signal and a monitoring signal accompanying such a main signal, The case where it is transmitted in the direction opposite to the arrow in the figure is included. Furthermore, the arrows in the figure conceptually indicate the flow of signals between the components, and in an actual device, it is not necessary for each signal to be faithfully exchanged along the path indicated by the arrows. . Moreover, in an actual apparatus, it is not necessary that each component is divided faithfully as shown in FIG.

  The time domain processing unit 2 performs channel selection of a desired physical channel, conversion to an intermediate frequency IF signal, A / D conversion, and quadrature detection from the high-frequency signal received from the antenna 1. Then, an IQ demodulated signal expressed in a complex form is generated and output.

  Based on the window position control signal output from the window position control unit 12, the window extraction unit 3 extracts a partial signal having an effective symbol length from the IQ demodulated signal output from the time domain processing unit 2 (that is, window extraction). And output to the FFT processing unit 4.

  The FFT processing unit 4 performs a Fourier transform on the partial signal of the effective symbol length of the IQ demodulated signal output from the window extraction unit 3 to convert the data on the time axis into the data on the subcarrier frequency axis. Output. The data on the frequency axis is output to a subsequent stage that performs frequency domain processing (not shown).

  The GI correlation calculation unit 5 calculates and outputs a guard interval correlation based on the IQ demodulated signal output by the time domain processing unit 2.

  The GI ISI distribution calculation unit 6 calculates and outputs a GI ISI distribution based on the guard interval correlation output from the GI correlation calculation unit 5.

  The transmission path characteristic EP calculation unit 8 calculates and outputs a transmission path characteristic echo profile based on the signal output from the FFT processing unit 4.

  The EP system ISI distribution calculation unit 9 calculates and outputs an EP system ISI distribution based on the transmission path characteristic echo profile output from the transmission path characteristic EP calculation unit 8.

  The EP system window position information detection unit 10 detects EP system window position information based on the EP system ISI distribution output from the EP system ISI distribution calculation unit 9. As will be described in detail later, at least one or more EP system window position information is detected.

  The window position determination control unit 13 generates a window position control signal based on the GI system ISI distribution output from the GI system ISI distribution calculation unit 6 and the EP system window position information output from the EP system window position information detection unit 10. Generate and output to the window extraction unit 3.

  In the above, the time domain processing unit 2 corresponds to the time domain processing means described in each claim, and the window extraction unit 3 corresponds to the window extraction means. The FFT processing unit 4 corresponds to an FFT processing unit, the GI correlation calculation unit 5 corresponds to a GI correlation calculation unit, and the GI system ISI distribution calculation unit 6 corresponds to a GI system ISI distribution calculation unit. Further, the transmission path characteristic EP calculation unit 8 corresponds to transmission path characteristic EP calculation means, and the EP system ISI distribution calculation section 9 corresponds to EP system ISI distribution calculation means. The EP window position information detector 10 corresponds to an EP window position information detector, and the window position determination controller 13 corresponds to a window position controller.

  In this embodiment, based on the GI system ISI distribution obtained from the time domain signal before FFT processing and the EP system window position information obtained from the frequency domain signal after FFT processing, the window position is such that the ISI is minimized. An IQ demodulated signal can be extracted. As a result, window position control can be performed with high accuracy and reception performance can be improved.

  Below, the effect of this embodiment mentioned above is demonstrated in detail. First, a basic concept of a method for detecting an appropriate window extraction timing based on the ISI distribution will be described.

  First, FIG. 2 is a diagram showing a data configuration example of transmission symbols in the IQ demodulated signal. A time axis is set in the direction from left to right in the figure. For example, in ISDB-T, which is a Japanese terrestrial digital television broadcast, a guard interval is provided as a countermeasure against multipath.

  This guard interval (abbreviated as GI as appropriate in the figure and the following description) is arranged so that a part located at the end of the effective symbol section is copied to the start end of the symbol as shown in FIG. is there. As a result, even if a delayed wave delayed by a multipath shorter than the GI length is superimposed, orthogonality between subcarriers can be maintained by performing window extraction of the IQ demodulated signal at an extraction timing at which intersymbol interference does not occur.

  Here, the entire IQ demodulated signal has a configuration in which a large number of transmission symbol intervals are continuous, that is, a configuration in which GI intervals and effective symbol intervals are alternately arranged. However, in the FFT processing, only the effective symbol length must be extracted. That is, it is necessary to detect an extraction timing for appropriately extracting a partial signal having an effective symbol length with respect to an IQ demodulated signal having continuous transmission symbol intervals.

  Further, since the delayed signal due to multipath is superimposed on the actual IQ demodulated signal, the extraction timing is detected so that ISI (Inter Symbol Interference) indicating inter-symbol interference caused by transmission symbols positioned before and after is minimized. There is a need.

  FIG. 3 is a diagram for explaining the ISI distribution and its basic method of obtaining. In the illustrated example, the case of an IQ demodulated signal in which two main waves and a delayed wave delayed by a GI length from the main wave are superimposed is shown. In all of FIGS. 3A to 3C, a time axis that is synchronized with the direction from the left to the right in the drawing is set.

  First, in FIG. 3A, the IQ demodulated signal of this example is superimposed with two multipath waves of one main wave and one delayed wave delayed by the GI length as described above. However, in the figure, the main wave and the delayed wave are shown separately arranged one above the other. With respect to the IQ demodulated signal in this example, the extraction timing shown in window extraction A shown in the figure, that is, the timing of the end of the GI section (starting end of the effective symbol period) of the kth transmission symbol in the figure in the main wave. When window extraction of the effective symbol length is performed, ISI does not occur at all in the partial signal extracted by the window extraction A.

  That is, in the case of this window extraction A, only the effective symbol section of the kth transmission symbol is extracted for the main wave. On the other hand, for the delayed wave, only the effective symbol length is extracted from the beginning of the same k-th transmission symbol. For this reason, the extracted partial signal is composed of only the signal components in the same k-th transmission symbol, and the transmission symbols before and after the (k−1) -th and (k + 1) -th transmission symbols in the figure). Not affected at all.

  On the other hand, in the case of window extraction B, which is an extraction timing slightly earlier than this window extraction A, the terminal portion of the (k−1) th transmission symbol is also extracted with respect to the delayed wave. For this reason, ISI is generated under the influence of the (k−1) th transmission symbol. Conversely, in the case of window extraction C, which is an extraction timing slightly later than window extraction A, the start end portion of the (k + 1) th transmission symbol with respect to the main wave is also extracted. For this reason, even in this case, ISI occurs due to the influence of the (k + 1) th transmission symbol.

  The reception performance degrades as the window extraction is performed at the extraction timing where the influence of ISI is large. For this reason, in order to improve reception performance, it is necessary to perform window extraction at an extraction timing at which the influence of ISI is minimized.

  Here, as one of the methods for obtaining the ISI distribution indicating the time change of the ISI power that shows the magnitude of the influence of ISI, there is a method of using an echo profile as shown in FIG. An echo profile (abbreviated as EP in the drawings and in the following description as appropriate) is equivalent to a so-called known delay profile. That is, it is represented by a combination of impulse responses corresponding to the main wave and the delayed wave, and this can be handled as a model representing the relationship between the delay time and the received power between the main wave and the delayed wave. The example of FIG. 3B is an echo profile including an impulse response g1 corresponding to the main wave and an impulse response g2 corresponding to the delayed wave in the IQ demodulated signal of FIG. In this example, the impulse response g2 corresponding to the delayed wave is temporally delayed by the GI length with respect to the impulse response g1 corresponding to the main wave, and the received power is low.

  Next, the value is set to 0 by the width of the section P, and the value is simply decreased from 1 to 0 at the width of the section Q before the section P, and after the section P, the value is from 0 to 1 at the width of the section Q. Set the convolution function X, which simply increases to For example, the width of the section P may be set to the guard interval section width. Further, the width of the section Q may be set to a half width obtained by subtracting the guard interval section width from the effective symbol section width, for example. Then, the ISI distribution shown in FIG. 3C can be obtained by performing a convolution operation by moving the convolution function X with respect to the echo profile over time. That is, while moving the convolution function X with time, the reception power sum of the echo profile outside the convolution function X at that time is calculated, thereby indicating the magnitude of the influence of ISI, that is, obtaining the ISI power.

  The ISI distribution shown in FIG. 3C shows the time change of the ISI power. As is apparent from the drawing, the extraction timing corresponding to the window position A, that is, the kth transmission symbol in the figure in the main wave. At the timing of the end of the GI section (starting end of the effective symbol section) in ISI, the ISI power is minimized, which is the optimum extraction timing for performing window extraction. In short, the ISI distribution is obtained, and window extraction may be performed at the timing at which the influence of ISI is minimized, that is, the ISI power is minimized. In addition, as window extraction is performed much earlier or later than this optimum extraction timing, ISI power increases and reception performance deteriorates as can be seen from FIG.

  In addition, you may set the predetermined width which increased / decreased the width | variety of the said area P and the area Q suitably as needed. In addition, the width of the section Q before and after the section P may not be set to the same width before and after the section P.

  Next, specific embodiments will be described. In the present embodiment, the ISI distribution is calculated from the time domain signal before FFT processing. Further, the ISI distribution is calculated from the frequency domain signal after the FFT processing, and the window position information is detected based on the ISI distribution. Then, optimal window position control is performed based on the ISI distribution obtained from the time domain signal and the window position information obtained from the frequency domain signal.

(A) Detection Using GI Correlation in Time Domain First, a method for calculating the ISI distribution based on the guard interval correlation in the time domain will be specifically described.

  FIG. 4 is a block diagram showing a detailed configuration example of the GI correlation calculation unit 5 and the GI system ISI distribution calculation unit 6 shown in FIG.

  In FIG. 4, the GI correlation calculation unit 5 includes a delay unit 21, a complex conjugate conversion unit 22, and a multiplication unit 23. The GI correlation calculation unit 5 delays the IQ demodulated signal output from the time domain processing unit 2 and the IQ demodulated signal by an effective symbol interval length by the delay unit 21 and then performs complex conjugate conversion by the complex conjugate conversion unit 22. By multiplying the signal by the multiplier 23, the guard interval correlation is calculated and output.

  The GI system ISI distribution calculation unit 6 includes a GI system symbol average unit 24 and a GI system moving average unit 25. The GI system ISI distribution calculating unit 6 calculates the guard interval correlation calculated by the GI correlation calculating unit 5 after the GI system symbol averaging unit 24 averages the symbol direction, and then the GI system moving average unit 25 has the GI length. By calculating the moving average with twice the width, the ISI distribution based on the guard interval correlation, that is, the GI system ISI distribution is calculated and output. Note that the GI ISI distribution in this example is output in the form of a time function gmov (t).

  The calculation method of the ISI distribution using the guard interval correlation as described above will be described in more detail using a specific example of a waveform.

  FIGS. 5A to 5E show the GI correlation calculation unit 5 and the GI system ISI distribution calculation unit 6 from the IQ demodulated signal to the GI when the IQ demodulated signal is composed of a multipath single wave having only the main wave. It is a figure showing the course of change of a signal until it generates system ISI distribution. FIG. 5A shows a multipath IQ demodulated signal, FIG. 5B shows a delayed signal output from the delay unit 21 of the GI correlation calculation unit 5, and FIG. 5C shows the GI. FIG. 5D shows a signal output by the GI symbol average unit 24 of the GI ISI distribution calculation unit 6, and FIG. 5E shows the GI system. A signal output from the GI moving average unit 25 of the ISI distribution calculating unit 6, that is, a GI ISI distribution is shown. In all of FIGS. 5A to 5E, a time axis that is synchronized with the direction from the left to the right in the drawing is set.

  First, the GI correlation calculation unit 5 inputs an IQ demodulated signal shown in FIG. Then, the input IQ demodulated signal is delayed by the effective symbol length by the delay unit 21 to generate the delayed signal shown in FIG. Thereafter, the delayed signal and the IQ demodulated signal are multiplied by the multiplier 23 to calculate and output the guard interval correlation of FIG. As described above with reference to FIG. 2, in the same transmission symbol period, the GI period is almost the same as the end part of the effective symbol period and has a high correlation. Therefore, the correlation power of the guard interval correlation is high during the end portion of the effective symbol period. However, since there is almost no correlation with each other in the period other than the above, the correlation power of the guard interval correlation is low. As a result, the GI correlation calculation unit 5 calculates a guard interval correlation such that the level is increased only for the period of the end portion of the effective symbol period for each transmission symbol period as shown in FIG.

  Since the guard interval correlation calculated by the GI correlation calculation unit 5 oscillates with an amplitude having a small level and is unstable, the GI symbol average unit 24 of the GI ISI distribution calculation unit 6 moves in the symbol direction. Average. As a result, the signal waveform of the guard interval correlation is shaped as shown in FIG. 5D, and the correlation power is stabilized.

  Thereafter, the GI moving average unit 25 performs a moving average calculation by convolving a rectangular wave having a certain interval width with the averaged signal of the guard interval correlation. Specifically, the moving average calculation is performed by integrating the guard interval correlation signals in a certain section width and moving the area to be integrated. For example, the certain section width may be set to a width twice as long as the GI length. As a result, as shown in FIG. 5E, a substantially trapezoidal shape in which a constant high level is maintained in the period of each GI section in the IQ demodulated signal, and the width of the GI section is simply increased and decreased before and after that. A signal indicating the level change is generated.

  In the present embodiment, the signal shown in FIG. 5E is treated as a GI ISI distribution calculated based on the guard interval correlation. However, the GI system ISI distribution indicates the time change of AISI (anti-ISI) power. That is, in the ISI distribution shown in FIG. 3C, the influence of ISI increases in proportion to the magnitude of ISI power, that is, the timing with the lowest ISI power is set as the optimum extraction timing. On the other hand, in the GI ISI distribution shown in FIG. 5E, the influence of ISI is reduced in proportion to the magnitude of AISI power, that is, the timing with the highest AISI power is the optimum extraction timing. . In the example of the multipath single wave shown in the figure, a window of effective symbol length at any extraction timing during the period in which the AISI power having the highest GI ISI distribution is maintained constant, that is, each GI period in the IQ demodulated signal. Extraction may be performed.

  Next, FIG. 6A shows the change of the signal waveform when calculating the GI ISI distribution by performing the same processing on the IQ demodulated signal composed of the multipath two waves of the main wave and the delayed wave. FIG. 6 (a) to 6 (e) correspond to FIGS. 5 (a) to 5 (e), respectively. In this example, a description will be given using an example in which the delayed wave is delayed by the GI length from the main wave.

  In the case of these two multipath waves, the IQ demodulated signal shown in FIG. 6A is input to the GI correlation calculation unit 5 and the input signal is delayed by the effective symbol length by the delay unit 21 as in FIG. The delayed signal of b) is generated. Then, the delayed signal and the IQ demodulated signal are multiplied by the multiplication unit 23, whereby a guard interval correlation indicating a two-stage high correlation power state as shown in FIG. 6C is calculated. That is, between the IQ demodulated signal in FIG. 6 (a) and the delayed signal in FIG. 6 (b), the components of each main wave are in a state of high correlation power during the same period as in FIG. 5 (c). At the same time, the delay waves also have a relatively high correlation power (but lower than the high-level state of the main wave) in the period of the end portion of the effective symbol period.

  As described above, when the guard interval correlation is calculated for the IQ demodulated signal on which a plurality of multipath waves are superimposed, a state in which the correlation power is relatively high as many as the number of multipath waves occurs, and the time difference and correlation between them occur. The power ratio has the same relationship as the delay time between the multipath waves themselves and the received power ratio. This is similar to the relationship between the impulse responses g1 and g2 in the echo profile shown in FIG. In short, it can be considered that the guard interval correlation calculates a signal waveform obtained by convolving a rectangular wave having a GI long width with respect to the echo profile.

  The GI symbol average unit 24 of the GI ISI distribution calculation unit 6 performs averaging in the symbol direction on the calculated guard interval correlation, as shown above, and the guard interval correlation is calculated as shown in FIG. The signal waveform is shaped. After that, the GI moving average unit 25 calculates a moving average with a width twice as long as the GI length for the shaped guard interval correlation, and as shown in FIG. A GI system ISI distribution indicating a time change of the substantially mountain-shaped AISI power having the following is calculated.

  Each local maximum point L is located at the end of each GI section of the main wave in the IQ demodulated signal (the start of each effective symbol section). Therefore, in the GI ISI distribution shown in FIG. 6 (e), the time corresponding to the local maximum point L can be regarded as the optimum extraction timing at which the window extraction of the effective symbol length can be performed with the least influence of ISI.

  Note that the GI ISI distribution has a signal waveform that is closer to that obtained when there is no multipath shown in FIG. 5E when the reception power of the multipath delay wave is small. That is, since the GI ISI distribution is calculated based on the guard interval correlation, it is not so sensitive to the multipath delayed wave. Therefore, there is a demerit that the extraction timing of window extraction detected based on the GI system ISI distribution cannot be detected with high accuracy for multipath delayed waves. However, in the GI system ISI distribution, the AISI power with respect to the main wave is correctly calculated in almost the transmission symbol period, so that it is a rough distribution in terms of the transmission symbol period, but is sufficiently accurate. In other words, there is a merit that the extraction timing of window extraction detected based on the GI system ISI distribution is not greatly mistaken for each transmission symbol.

(B) Detection Using Transmission Line Characteristic EP in Frequency Domain Next, a method for calculating the ISI distribution and window position information using the transmission line characteristic echo profile in the frequency domain will be specifically described.

  FIG. 7 is a block diagram illustrating a detailed configuration example of the transmission path characteristic EP calculation unit 8, the EP system ISI distribution calculation unit 9, and the EP system window position information detection unit 10 illustrated in FIG.

  In FIG. 7, the transmission path characteristic EP calculation unit 8 includes a transfer characteristic calculation unit 31, an SP generation unit 32, a window multiplication unit 33, and an IFFT processing unit 34.

  As described above with reference to FIG. 1, the FFT processing unit 4 performs a Fourier transform process on the IQ demodulated signal output from the window extraction unit 3. At this time, the signal output from the FFT processing unit 4 includes a distributed pilot (Scattered) whose transmission value is known to a known subcarrier in an OFDM symbol space having a two-dimensional subcarrier frequency direction and symbol time direction. Pilot) signal (hereinafter referred to as pilot signal) is superimposed.

  An output signal from the FFT processing unit 4 is input to the transmission path characteristic EP calculation unit 8. Then, in the transmission line characteristic EP calculation unit 8, the transfer characteristic calculation unit 31 divides the output signal of the FFT processing unit 4 by the pilot signal whose transmission value generated by the SP generation unit 32 is known, so that a known sub Calculate the transfer characteristics of the carrier. It should be noted that the transfer characteristics of data subcarriers other than the subcarrier of the pilot signal are interpolated with zero. Then, the window multiplier 33 multiplies the transfer characteristic signal output from the transfer characteristic calculator 31 by a window function (for example, a so-called cosine roll-off filter window), and then the IFFT processor 34 performs an inverse Fourier transform process. I do. As a result, a transmission path characteristic echo profile as shown in FIG. 3B is calculated.

  The EP ISI distribution calculation unit 9 has an EP symbol average unit 35 and an EP moving average unit 36. In this EP system ISI distribution calculation unit 9, the EP system symbol averaging unit 35 averages the transmission path characteristic echo profile calculated by the transmission path characteristic EP calculation unit 8 in the symbol direction, and then the EP system moving average unit 36. Calculates the moving average in the subcarrier direction, thereby calculating and outputting the ISI distribution based on the transmission path characteristic echo profile, that is, the EP-based ISI distribution.

  The EP system window position information detection unit 10 includes an EP system peak detection unit 37. This EP system peak detector 37 detects the maximum point of the EP system ISI distribution output from the EP system ISI distribution calculator 9, and outputs the extraction timing taddr corresponding to the maximum point as EP system window position information. To do.

  A method for calculating the ISI distribution and window position information using the transmission path characteristic echo profile as described above will be described in more detail using specific examples of waveforms.

  8 (a) to 8 (c) show the above-described transmission path characteristic EP calculation unit 8 and EP system ISI distribution calculation unit 9 when the IQ demodulated signal is composed of two main-path and delayed multipath waves. And it is a figure showing an example of the process of calculating EP system window position information by the EP system window position information detection part 10. FIG. FIG. 8A shows an example of the transfer characteristic output from the transfer characteristic calculation unit 31 in the subcarrier direction, and FIG. 8B shows the transmission line characteristic output from the IFFT processing unit 34. An echo profile is shown. In this example, it is assumed that a pilot signal is superposed every three subcarriers on the signal after the FFT processing output from the FFT processing unit 4. FIG. 8C shows an EP ISI distribution output from the EP moving average unit 36. The EP-based ISI distribution shown in FIG. 8C shows the time change of the AISI power in the same manner as the GI-based ISI distribution shown in FIG. 5E or 6E. That is, in the EP-based ISI distribution shown in FIG. 8C, the influence of ISI is reduced in proportion to the magnitude of AISI power, that is, the timing with the highest ASIS power is the optimum extraction timing.

  First, as shown in FIG. 8 (a), the transfer characteristic calculation unit 31 pilot signals (abbreviated as SP subcarriers in the figure) superposed every predetermined subcarrier (three in this example) in the subcarrier direction. ), The transfer characteristic in the data subcarrier is interpolated to 0, and a transfer characteristic signal is output. Then, the IFFT processing unit 34 performs inverse Fourier transform after the window multiplication unit 33 multiplies the transfer characteristic signal by the window function, so that each multipath wavenumber (in this example, as shown in FIG. 8B). A transmission path characteristic echo profile composed of combinations of the number of impulse responses corresponding to (two waves) is calculated. For example, a cosine roll-off filter may be used as the window function.

  As described above, in this example, the transmission characteristic of the pilot signal is calculated every three subcarriers. For this reason, at the time of calculating the transmission path characteristic echo profile, the transmission path characteristic echo profile is calculated as a signal folded back with a 1/3 effective symbol length in the time direction by aliasing, which is a so-called aliasing signal. That is, the impulse response of the main wave is arranged at a time interval corresponding to 1/3 of the effective symbol length. Further, the impulse responses of the respective delayed waves are spaced apart from the corresponding main wave impulse responses by the same delay time. The subcarrier interval is the reciprocal of the effective symbol length.

  Then, the EP-system symbol averaging unit 35 averages the transmission path characteristic echo profile calculated by the IFFT processing unit 34 in the symbol direction. Then, the EP system moving average unit 36 performs a moving average in the subcarrier direction on the averaged transmission path characteristic echo profile calculated by the EP system symbol averaging unit 35 to calculate an EP system ISI distribution.

  Then, the EP system symbol averaging unit 35 averages the folded transmission path characteristic echo profile of FIG. 8B in the symbol direction. The EP moving average unit 36 calculates the EP ISI distribution shown in FIG. 8C by performing a moving average by convolving the convolution function Y on the averaged transmission path characteristic echo profile. The EP system ISI distribution is also a signal that is folded back with a 1/3 effective symbol length. The convolution function Y may be a function obtained by subtracting the convolution function X in FIG. 3B from 1.0, for example. That is, the convolution function Y has a value of 1 for the width of the section P, and the value is simply increased from 0 to 1 with the width of the section Q before the section P, and after the section P with the width of the section Q. Is a function that simply decreases from 1 to 0. The section P and the section Q are as described above.

  Then, the EP peak detection unit 37 of the EP window position information detection unit 10 detects at least one local maximum value in the EP system ISI distribution, and uses the extraction timings taddr1 to taddrN corresponding to the detected local maximum values in the EP system. Output as window position information. In the example of FIG.

  When detecting the extraction timing based on the EP ISI distribution, the extraction timing can be detected with high accuracy because the calculation is based on the transfer characteristics even when the reception power of the multipath delayed wave is low. . That is, there is an advantage that detection accuracy is high.

  However, when the extraction timing is detected based on the EP system ISI distribution, since at least one or more extraction timings taddr0 to taddrN are detected as the EP system window position information, it is necessary to select which extraction timing is optimal. is there.

  Therefore, in the present embodiment, only one optimum extraction timing can be detected based on the GI system ISI distribution and the EP system window position information. That is, the window position determination control unit 13 selects an optimum extraction timing from among the extraction timings detected as at least one EP window position information using the GI system ISI distribution, and selects the selected extraction timing as an EP system. The optimum window position information is used. Then, a window position control signal corresponding to the EP system optimum window position information is generated and output to the window extraction unit 3 to perform optimum window position control.

  FIG. 10 is a block diagram showing a detailed configuration example and functions of the window position determination control unit 13 shown in FIG.

  In FIG. 10, the window position determination control unit 13 includes an EP window position information selection unit 14 and a window position control unit 12.

  The EP window position information selection unit 14 uses at least one of the EP window position information output by the EP window position information detection unit 10 using the GI ISI distribution output by the GI ISI distribution calculation unit 6. The optimum extraction timing is selected from the two or more detected extraction timings, and the selected extraction timing is output to the window position control unit 12 as EP system optimum window position information.

  The window position control unit 12 generates a window position control signal based on the EP system optimum window position information output from the EP system window position information selection unit 14 and outputs the window position control signal to the window extraction unit 3.

  In the above description, the EP window position information selection unit 14 corresponds to the EP window position information selection means described in each claim.

  Here, the EP window position information selection unit 14 will be described in more detail. The EP window position information selection unit 14 includes a level detection unit 41 and a maximum selection unit 42. The time function gmov (t) of the GI system ISI distribution is input from the GI system ISI distribution calculation unit 6, and N extraction timings taddr <b> 1 to N are input from the EP window position information detection unit 10 as EP window position information.

Then, in the EP system window position information selection unit 14, first, the level detection unit 41 uses the time functions gmov (t) of the GI system ISI distribution for each of the N extraction timings taddr1 to N, and uses the N AISI powers tval1. -N is calculated. That is,
tval1-N = gmov (taddr1-N)
Ask for.

  The maximum selection unit 42 selects the maximum one of the N pieces of AISI powers tval1 to tivalN, and outputs the extraction timing taddr0 using the extraction timing corresponding to the selected AISI power as the optimum window position information. That is, optimal window position control is performed by selecting an extraction timing that minimizes ISI, that is, maximizes AISI power, using GI system ISI distribution from N extraction timings that are EP system window position information. be able to.

  And the window position control part 12 produces | generates the window position control signal corresponding to EP system optimal window position, and outputs it to the window extraction part 3 (refer FIG. 1). As described above, even when there are a plurality of local maximum points within the effective symbol long term in the EP-based ISI distribution, it is possible to select the extraction timing with the minimum ISI and generate the optimal window position information.

  As described above, in the receiving apparatus 100 according to the present embodiment, the time domain processing unit 2 that performs time domain processing on the OFDM signal received from the antenna 1 and outputs an IQ demodulated signal, and the IQ demodulated signal A window extraction unit 3 that performs window extraction based on a window position control signal, an FFT processing unit 4 that performs FFT processing on the IQ demodulated signal extracted by the window extraction unit 3, and guards the IQ demodulated signal GI correlation calculation unit 5 that calculates interval correlation, GI ISI distribution calculation unit 6 that calculates GI ISI distribution based on the guard interval correlation, and transmission path characteristics from the signal FFT processed by the FFT processing unit 4 A transmission path characteristic EP calculation unit 8 that calculates an echo profile, and an EP ISI distribution is calculated based on the transmission path characteristic echo profile. EP system ISI distribution calculating section 9, EP system window position information detecting section 10 for detecting at least one EP system window position information based on the EP system ISI distribution, GI system ISI distribution and EP system window A window position determination control unit 13 for generating the window position control signal based on position information and outputting the window position control signal to the window extraction unit 3.

  In the receiving method in the above embodiment, the time domain processing step performed by the time domain processing unit 2 to perform the time domain processing on the OFDM signal received from the antenna 1 and output the IQ demodulated signal, and the IQ demodulated signal A window extraction step performed by the window extraction unit 3 that performs window extraction based on a window position control signal, an FFT processing step performed by the FFT processing unit 4 on the IQ demodulated signal window extracted by the window extraction step, GI correlation calculation step performed by the GI correlation calculation unit 5 so as to calculate the guard interval correlation from the IQ demodulated signal, and GI system performed by the GI system ISI distribution calculation unit 6 so as to calculate the GI system ISI distribution based on the guard interval correlation. An ISI distribution calculation step, and a transmission path characteristic echo profile from the FFT processed signal by the FFT processing step. A transmission path characteristic EP calculation step performed by the transmission path characteristic EP calculation unit 8 so as to calculate the transmission line, and an EP system performed by the EP system ISI distribution calculation unit 9 so as to calculate an EP system ISI distribution based on the transmission path characteristic echo profile An ISI distribution calculation step, an EP window position information detection step performed by the EP window position information detection unit 10 to detect at least one or more EP window position information based on the EP ISI distribution, and the GI system A window position determination control step performed by the window position determination control unit 13 so as to generate the window position control signal based on the ISI distribution and the EP system window position information and to output the window position control signal to the window extraction step.

  When configured as described above, the IQ demodulated signal is obtained at a window position where ISI is minimized based on the GI ISI distribution obtained from the time domain before FFT processing and the EP window position information obtained from the frequency domain after FFT processing. Can be window extracted. As a result, the window position control can be performed with high accuracy, so that the reception performance can be improved.

  In the above embodiment, the IQ demodulated signal is described as being composed of two multipath waves of one main wave and one delayed wave, but the present invention is not limited to this. For example, although not particularly illustrated, when the IQ demodulated signal is composed of three or more multipath waves in which a plurality of delay waves are superimposed on one main wave, the EP ISI distribution calculation unit 9 may All the impulse responses corresponding to the waves are convolved with the convolution function Y to calculate the EP system ISI distribution, and at least one EP system window position information detection unit 10 is detected on the EP system ISI distribution. The extraction timings taddr1 to N, which are EP system window position information corresponding to the local maximum points, are detected, and the EP system window position information selection unit 14 selects the most appropriate extraction timing using the GI system ISI distribution. You may make it output as extraction timing taddr0 which is system optimal window position information.

In addition, this embodiment is not restricted above, A various deformation | transformation is possible. Hereinafter, such modifications will be described.
(1) When determining validity of EP window position information and adopting GI window position information when it is not valid In the above embodiment, out of N extraction timings taddr1 to N that are EP window position information The extraction timing taddr0, which is the EP system optimal window position information selected from the above, is unconditionally set as the optimal window position information, but is not limited thereto. That is, the validity of the EP system optimum window position information is determined, and when it is not valid, the GI system window position information calculated based on the GI system ISI distribution may be used as the optimum window position information.

  First, before describing a specific modification, problems in a method for calculating EP window position information based on an EP ISI distribution will be described. In the case of the method of detecting EP system window position information based on the EP system ISI distribution, if the time difference between the most preceding wave and the last wave, that is, the delay spread is very long, the detection of the extraction timing is greatly mistaken by aliasing. There is a demerit. In the following description, it is assumed that the leading wave is the main wave and the last wave is the delayed wave.

  Specifically, for example, as shown in FIG. 9, a case is assumed in which the transmission path characteristic echo profile is calculated by aliasing with a 1/3 effective symbol length by aliasing. In this case, when the time difference between the main wave and the delayed wave becomes longer than 1/6 effective symbol length, it is not the combination of the impulse responses that constitute the original transmission path characteristic echo profile, but the combination of the closest impulse responses. There is a possibility that the configuration of the transmission path characteristic echo profile is mistaken.

  In other words, the time difference between the original main wave and the delayed wave of the virtual image generated by aliasing is shorter than the time difference between the original main wave and the delayed wave. Therefore, when the delay spread is longer than half of the period that is turned back by aliasing, there is a demerit that the extraction timing calculated based on the transmission path characteristic echo profile is greatly mistaken.

  Therefore, in the first modification, the validity of the EP system optimum window position information is determined. If the validity is not valid, the window position control unit 12 uses the GI system window position information calculated based on the GI system ISI distribution as the optimum window position information. Output to.

  FIG. 11 is a block diagram illustrating a configuration example of the receiving apparatus according to the first modified example, and corresponds to FIG. 1 in the above embodiment. FIG. 12 is a block diagram illustrating a detailed configuration example of the GI correlation calculation unit 5, the GI system ISI distribution calculation unit 6, and the GI system window position information detection unit 7 in the first modification example, and is a diagram in the above embodiment. 4 corresponds to FIG. In addition, about the same site | part as the said embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted suitably.

  11 and 12, the window position determination control unit 13A includes a GI window position information detection unit 7, an EP window position information selection unit 14, a window position determination unit 11, and a window position control unit 12. Have.

  The GI window position information detection unit 7 has a GI peak detection unit 26. This GI system peak detection unit 26 detects the maximum value point of the GI system ISI distribution output from the GI system ISI distribution calculation unit 6, and outputs the extraction timing gaddr corresponding to the maximum value point as GI system window position information. .

  FIG. 13 is a block diagram illustrating a detailed configuration example and functions of the window position determination unit 11 illustrated in FIG. 11.

  In FIG. 13, the window position determination unit 11 includes a level detection unit 41 and a determination unit 43.

  The level detection unit 41 uses the time function gmov (t) of the GI system ISI distribution output from the GI system ISI distribution calculation unit 6 to perform AISI power of the GI system ISI distribution at the extraction timing gaddr that is GI system window position information. geval and the ASIS power tval of the GI system ISI distribution at the extraction timing taddr0, which is the EP system optimal window position information, are calculated and output to the determination unit 43.

Then, the determination unit 43 calculates an evaluation value val for evaluating the validity of the EP system optimum window position information based on the ASIS power gival and tival of the GI system ISI distribution output from the level detection unit 41. That is,
val = (geval-teval) / teval
Ask for.

  Further, the determination unit 43 sets one of the GI window position information and the EP system optimum window position information as the optimum window position information by comparing the evaluation value val with a preset threshold value threshold value.

That is,
val ≧ thresholdvalue
Is set, the extraction timing taddr0 that is the EP system optimum window position information is set to the extraction timing addr that is the optimum window position information, and val <thresholdvalue.
In this case, the extraction timing gaddr that is GI window position information is set to the extraction timing addr that is optimum window position information.

  Then, the determination unit 43 outputs the extraction timing addr as the optimal window position information to the window position control unit 12. The window position control unit 12 generates a window position control signal based on the optimum window position information and outputs the window position control signal to the window extraction unit 3.

  Here, the determination content of the determination part 43 mentioned above is demonstrated concretely. FIG. 14 shows an example of the relationship between extraction timing gaddr, which is GI system window position information, AISI power geval, time function gmov (t) of GI system ISI distribution, extraction timing taddr0 which is EP system optimal window position information, and ASIS power tival. FIG. FIG. 14 is an enlarged view of one transmission symbol section of the time function gmov (t) shown in FIG. 6 (e).

  In FIG. 14, the EP system optimum window obtained using the AISI power value geval corresponding to the extraction timing gaddr which is the GI system window position information obtained using the guard interval correlation and the transmission path characteristic echo profile. The AISI power value tval corresponding to the extraction timing taddr0, which is position information, should normally be approximately the same or close.

  However, as described above, when guard interval correlation is used, detection of the extraction timing is not greatly mistaken. However, if the reception level of the multipath delayed wave is low, the detection sensitivity of the extraction timing is likely to decrease, so fine accuracy Cannot be expected. On the other hand, when the transmission line characteristic echo profile is used, if the delay spread is short, the extraction timing can be detected with high accuracy even if the reception level of the multipath delayed wave is small, but if the delay spread is long, aliasing is possible. Because of the transmission path characteristic echo profile turned back, the detection of the extraction timing may be mistaken.

Therefore, the determination unit 43
val ≧ thresholdvalue
The EP system optimal window position information is considered to be close to the GI system window position information, the EP system window position information is determined to be valid without making a large mistake, and the EP system optimal window position information is determined. Is set to the extraction timing addr which is the optimum window position information. Also,
val <thresholdvalue
In this case, it is considered that the EP system optimum window position information is greatly deviated from the GI system window position information, and the EP system optimum window position information is largely incorrect and determined to be invalid, and is the GI system window position information. The extraction timing gaddr is set to the extraction timing addr that is optimum window position information.

  As described above, the window position determination unit 11 determines the validity of the EP system optimal window position information, and when it is appropriate, the EP system optimal window position information is optimal, and when it is not appropriate, the GI system window position information is optimal. It outputs to the window position control part 12 as window position information.

  When the present modification is configured as described above, the GI system window position information obtained from the time domain before FFT processing and the EP system window position information obtained from the frequency domain after FFT processing are always utilized, and always The IQ demodulated signal can be window extracted at a window position where ISI is minimized. As a result, window position control can be performed with high accuracy and reception performance can be improved. And in the case of this modification, the window position determination control part 13 can perform the judgment of the validity of EP system window position information, and the treatment when it is not valid.

  In addition to those already described above, the methods according to the above-described embodiments and modifications may be used in appropriate combination.

1 antenna 2 time domain processing unit (corresponding to time domain processing means)
3 Window extraction part (equivalent to window extraction means)
4 FFT processing unit (equivalent to FFT processing means)
5 GI correlation calculation unit (equivalent to GI correlation calculation means)
6 GI ISI distribution calculator (equivalent to GI ISI distribution calculator)
7 GI window position information detector (corresponding to GI window position information detector)
8 Transmission path characteristic EP calculation unit (equivalent to transmission path characteristic EP calculation means)
9 EP system ISI distribution calculation part (equivalent to EP system ISI distribution calculation means)
10 EP window position information detector (equivalent to EP window position information detector)
DESCRIPTION OF SYMBOLS 11 Window position determination part 12 Window position control part 13, 13A Window position determination control part (equivalent to window position determination control means)
14 EP window position information selection unit (equivalent to EP window position information selection means)
DESCRIPTION OF SYMBOLS 21 Delay part 22 Complex conjugate conversion part 23 Multiplication part 24 GI system symbol average part 25 GI system moving average part 26 GI system peak detection part 31 Transfer characteristic calculation part 32 SP production | generation part 33 Window multiplication part 34 IFFT process part 35 EP system symbol Average part 36 EP system moving average part 37 EP system peak detection part 41 Level detection part 42 Maximum selection part 43 Judgment part 100,100A Receiver GI Guard interval EP Echo profile X Convolution function

Claims (4)

Time domain processing means for performing time domain processing on an OFDM signal received from an antenna and outputting an IQ demodulated signal;
Window extraction means for performing window extraction on the IQ demodulated signal based on a window position control signal;
FFT processing means for performing FFT processing on the IQ demodulated signal extracted by the window extraction means;
GI correlation calculating means for calculating a guard interval correlation from the IQ demodulated signal;
GI ISI distribution calculating means for calculating a GI ISI distribution based on the guard interval correlation;
Transmission path characteristic EP calculating means for calculating a transmission path characteristic echo profile from the signal FFT processed by the FFT processing means;
EP-based ISI distribution calculating means for calculating an EP-based ISI distribution based on the transmission path characteristic echo profile;
EP system window position information detecting means for detecting at least one or more EP system window position information based on the EP system ISI distribution;
Window position determination control means for generating the window position control signal based on the GI ISI distribution and the EP window position information and outputting the window position control signal to the window extraction means ;
Have
The window position determination control means includes
EP system window position information selection means for selecting one of at least one of the EP system window position information detected by the EP system window position information detection means using the GI system ISI distribution;
Window position control means for generating the window position control signal corresponding to the selected EP system window position information and outputting it to the window extraction means;
Have
The EP window position information is
EP system extraction timing indicating the time when the EP system ISI distribution reaches the maximum value is included,
The EP system window position information selection means calculates AISI power of the GI system ISI distribution at the EP system extraction timing, and the EP system window position at which the AISI power is maximum among the calculated at least one AISI power. A receiving apparatus , wherein information is selected . The window position determination control means includes
GI window position information detecting means for detecting GI window position information including a GI extraction timing indicating a maximum value in the GI ISI distribution ;
Window position determination means for performing determination based on the GI window position information, the EP window position information, and the GI ISI distribution, and selecting one of the GI window and EP window position information. and,
Have
The window position determination means includes
The AISI power of the GI system ISI distribution at the GI system extraction timing is calculated as the GI system AISI power,
Calculating the AISI power of the GI system ISI distribution at the EP system extraction timing included in the EP system window position information selected by the EP system window position information means as the EP system AISI power;
A determination value is calculated based on the GI AISI power and the EP AISI power,
If the determination value satisfies a predetermined threshold, the EP window position information selected by the EP window position information means is output to the window position control means,
The receiving apparatus according to claim 1, wherein when the determination value does not satisfy a predetermined threshold, the GI window position information is output to the window position control means . A time domain processing step for performing time domain processing on an OFDM signal received from an antenna and outputting an IQ demodulated signal;
A window extraction step for performing window extraction on the IQ demodulated signal based on a window position control signal;
An FFT processing step for performing FFT processing on the IQ demodulated signal extracted by the window extraction step;
A GI correlation calculating step of calculating a guard interval correlation from the IQ demodulated signal;
A GI ISI distribution calculating step for calculating a GI ISI distribution based on the guard interval correlation;
A transmission path characteristic EP calculating step for calculating a transmission path characteristic echo profile from the signal subjected to the FFT processing in the FFT processing step;
An EP ISI distribution calculating step for calculating an EP ISI distribution based on the transmission path characteristic echo profile;
EP system window position information detection step for detecting at least one or more EP system window position information based on the EP system ISI distribution;
A window position determination control step for generating the window position control signal based on the GI system ISI distribution and the EP system window position information and outputting the window position control signal to the window extraction step ;
The window position determination control step includes:
EP system window position information selection step of selecting one of the at least one EP system window position information detected by the EP system window position information detection step using the GI system ISI distribution;
A window position control step for generating the window position control signal corresponding to the selected EP system window position information and outputting it to the window extraction step;
Have
The EP window position information is
EP system extraction timing indicating the time when the EP system ISI distribution reaches the maximum value is included,
In the EP system window position information selection step, the AI system power of the GI system ISI distribution at the EP system extraction timing is calculated, and the EP system window position at which the AISI power is the maximum among the calculated at least one AISI power. A receiving method, wherein information is selected . The window position determination control step includes:
GI window position information detection step for detecting GI window position information including GI extraction timing indicating the time when the GI system ISI distribution reaches a maximum value ;
A window position determining step for performing determination based on the GI window position information, the EP window position information, and the GI ISI distribution and selecting one of the GI window and EP window position information. and,
Have
The window position determining step includes
The AISI power of the GI system ISI distribution at the GI system extraction timing is calculated as the GI system AISI power,
Calculating the AISI power of the GI system ISI distribution at the EP system extraction timing included in the EP system window position information selected in the EP system window position information step as the EP system AISI power;
A determination value is calculated based on the GI AISI power and the EP AISI power,
If the determination value satisfies a predetermined threshold, the EP window position information selected in the EP window position information step is output to the window position control step,
4. The receiving method according to claim 3 , wherein when the determination value does not satisfy a predetermined threshold, the GI window position information is output to the window position control step .

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