JP2014150469A - Equalization device and equalization method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to adaptively perform transmission path estimation even in radio wave environment where a fluctuation frequency is large.SOLUTION: An equalization device comprises: a transmission path characteristic division unit 130 for dividing a transmission path characteristic acting on a pilot carrier into components in a plurality of regions on two axes of a fluctuation frequency axis and a delay time axis; an SP transmission path characteristic distribution calculation unit 140 for calculating a physical quantities of the divided components of the plurality of regions; a desired transmission path characteristic distribution calculation unit 150 for calculating a physical quantity of a desired component including no unnecessary repeating component by using regularity with which pilot carriers are arranged and a statistical characteristic of a transmission path; and a desired transmission path characteristic extraction unit 160 for extracting a component of a region including the desired component from the divided plurality of regions on the basis of the calculated physical quantity of the desired component.

Description

  The present invention relates to an equalization apparatus and an equalization method.

  Many wireless communication systems and terrestrial digital broadcasting use an orthogonal frequency division multiplexing (OFDM) transmission scheme in which a plurality of orthogonal carriers are multiplexed and transmitted in one symbol. When this OFDM signal is received by a moving body such as a car, the signal is distorted due to reflection, diffraction, scattering, and fluctuation of the radio wave environment accompanying movement due to an obstacle such as a building.

  In order to compensate for the distortion, the receiver estimates the radio wave environment and multiplies the received signal by the inverse characteristic. Here, in order to estimate the radio wave environment, the transmitter inserts a known signal in addition to the effective data into the transmission signal, and the receiver calculates the transmission path distortion using the known signal, By interpolating between symbols, the radio wave environment in the data section is estimated (hereinafter referred to as transmission path estimation). In order to perform accurate reception even in a poor radio wave environment with severe fluctuations, it is necessary to improve transmission path estimation technology.

  Patent Document 1 describes a method of calculating a transmission path characteristic in a pilot carrier SP (Scattered Pilot), performing a two-dimensional discrete Fourier transform, and estimating a transmission path. In this prior art, first, a channel characteristic having a delay time and a variable frequency as variables is generated by performing two-dimensional Fourier transform on the carrier frequency and symbol time on the channel characteristic calculated by SP. FIG. 1 is a schematic diagram illustrating a conversion result of a two-dimensional Fourier transform in the case of a two-wave rice transmission path (a direct wave has no time variation and a delayed wave is a Rayleigh wave). In FIG. 1, reference numeral 700 is a desired transmission line characteristic, and reference numeral 800 is an unnecessary repetitive component. In FIG. 1, unnecessary repeating components 800 are hatched. The prior art eliminates the need for the second filter extraction region 901 by selecting the second filter extraction region 901 from the predetermined first filter extraction region 900 so as to include a component having a large power with respect to the signal subjected to the two-dimensional discrete Fourier transform. The repetitive component 800 is suppressed and a desired transmission line characteristic 700 is extracted. The conventional technique estimates the transmission path characteristics by performing a two-dimensional inverse Fourier transform on the extraction result. As described above, the conventional technique suppresses unnecessary repetitive components 800 in the delay time region and the variable frequency region, thereby interpolating the transmission path characteristics calculated by the SP between the carriers and between the symbols. The transmission path is estimated for the data section.

Japanese Patent No. 3820311

  The prior art described in Patent Document 1 can adaptively suppress the influence of repetitive components and Gaussian noise by filter extraction processing using two-dimensional Fourier transform. However, this conventional technique has a problem that when the fluctuating frequency is large, a repetitive component enters a region of interest, so that accurate transmission path characteristics cannot be obtained. For example, as shown in FIG. 2, in the case of a two-wave rice transmission line with a large time fluctuation, an unnecessary repetitive component 801 is included in the first filter extraction region 902 for extracting a desired transmission line characteristic. Therefore, the conventional technique described in Patent Document 1 cannot estimate an accurate transmission path.

  Therefore, an object of the present invention is to enable adaptive transmission path estimation even in a radio wave environment with a large fluctuation frequency.

An equalization apparatus according to one aspect of the present invention is provided.
A Fourier transform unit that converts a received signal including a pilot carrier into a signal in the frequency domain;
Based on the frequency domain signal transformed by the Fourier transform unit, a transmission line characteristic calculation unit for calculating a transmission line characteristic acting on the pilot carrier;
A transmission line characteristic dividing unit that divides the transmission line characteristic calculated by the transmission line characteristic calculation unit into components of a plurality of regions on two axes of a variable frequency axis and a delay time axis;
A transmission path characteristic distribution calculating section that calculates physical quantities of components of a plurality of regions divided by the transmission path characteristic dividing section;
The physical quantity of the repetitive component of the transmission path characteristic calculated by the transmission path characteristic calculation section from the physical quantity calculated by the transmission path characteristic distribution calculation section, the regularity of the distribution of the repetitive component, and the transmission path characteristic calculation section A desired transmission path characteristic distribution calculating unit that calculates the physical quantity of the desired component by using the statistical property of the desired component of the transmission path characteristic calculated in
Based on the physical quantity of the desired component calculated by the desired transmission path characteristic distribution calculating unit, the component of the area including the desired component is extracted from the components of the plurality of areas divided by the transmission path characteristic dividing unit. A desired transmission line characteristic extraction unit,
By combining the components extracted by the desired transmission line characteristic extracting unit, a transmission line characteristic combining unit that generates a transmission line characteristic in the frequency domain;
An equalization unit that compensates for transmission path distortion of the frequency domain signal converted by the Fourier transform unit using the frequency domain transmission path characteristic generated by the transmission path characteristic coupling unit, To do.

An equalization method according to an aspect of the present invention includes:
A Fourier transform process for transforming a received signal including a pilot carrier into a frequency domain signal;
A transmission path characteristic calculation process for calculating a transmission path characteristic acting on the pilot carrier based on the frequency domain signal transformed in the Fourier transform process;
A transmission line characteristic dividing process of dividing the transmission line characteristic calculated in the transmission line characteristic calculation process into components of a plurality of regions on two axes of a variable frequency axis and a delay time axis;
A transmission line characteristic distribution calculating process for calculating physical quantities of components of a plurality of regions divided in the transmission line characteristic dividing process;
From the physical quantity calculated in the transmission path characteristic distribution calculation process, the physical quantity of the repetitive component of the transmission path characteristic calculated in the transmission path characteristic calculation process, the regularity of the distribution of the repetitive component, and the transmission path characteristic calculation process A desired transmission path characteristic distribution calculating process for calculating the physical quantity of the desired component by using the statistical property of the desired component of the transmission path characteristic calculated in
Based on the physical quantity of the desired component calculated in the desired transmission path characteristic distribution calculating process, the component of the area including the desired component is extracted from the components of the plurality of areas divided in the transmission path characteristic dividing process. A desired transmission line characteristic extraction process,
By combining the components extracted in the desired transmission line characteristic extraction process, a transmission line characteristic combining process for generating a frequency domain transmission line characteristic;
An equalization process for compensating for transmission path distortion of a frequency domain signal transformed in the Fourier transform process using a frequency domain transmission path characteristic generated in the transmission path characteristic coupling process. To do.

  According to one embodiment of the present invention, transmission path estimation can be performed adaptively even in a radio wave environment with a large fluctuation frequency.

It is the schematic which shows the electric power distribution on the fluctuation frequency axis | shaft of a transmission-line characteristic when a time fluctuation is small in a two-wave rice transmission line, and a delay time axis. It is the schematic which shows the two-dimensional power distribution in the fluctuation frequency axis | shaft of a transmission-line characteristic when a time fluctuation is large in a two-wave rice transmission line, and a delay time axis. It is a functional block diagram which shows roughly the structure of the equalization apparatus which concerns on Embodiment 1-3. 3 is a schematic diagram showing a configuration of an OFDM symbol in Embodiment 1. FIG. FIG. 3 is a schematic diagram showing an arrangement of pilot carriers (SP) in the first embodiment. FIG. 3 is a schematic diagram showing the interval between repetitive components on the variable frequency axis and delay time axis of the transmission path characteristics in the first embodiment. 6 is a schematic diagram illustrating division of transmission path characteristics on a variable frequency axis and a delay time axis according to Embodiment 1. FIG. 6 is a schematic diagram illustrating an example of a pass band of a symbol time interpolation filter in Embodiment 1. FIG. In Embodiment 1, it is the schematic which shows the division | segmentation in the fluctuation frequency area | region of the transmission-line characteristic in a fluctuation frequency axis | shaft and a delay time axis | shaft. In Embodiment 1, it is the schematic which shows the two-dimensional power distribution of SP transmission-line characteristics in a variable frequency axis and a delay time axis. In Embodiment 1, it is the schematic which shows the two-dimensional power distribution of the desired transmission-line characteristic in a variable frequency axis | shaft and a delay time axis | shaft. In Embodiment 1, it is the schematic which shows the power ratio _mu and m of the area | region where the code | symbol of a fluctuation frequency is reverse. In Embodiment 2, it is the schematic which shows the two-dimensional two-dimensional power distribution when the division | segmentation number of a fluctuation frequency area | region is "5". In Embodiment 2, it is the schematic which shows the two-dimensional two-dimensional power distribution of a desired component when the division | segmentation number of a fluctuation frequency area | region is "5". FIG. 10 is a functional block diagram schematically showing a configuration of an equalization apparatus according to a fourth embodiment. In Embodiment 4, it is the schematic which shows the two-dimensional power distribution of the SP transmission line characteristic in the fluctuation | variation frequency axis | shaft and delay time axis | shaft in a 3 wave rice transmission line. In Embodiment 4, it is the schematic which shows the two-dimensional power distribution of the SP transmission line characteristic in the fluctuation | variation frequency axis | shaft and delay time axis | shaft in a 4-wave rice transmission line.

Embodiment 1 FIG.
FIG. 3 is a functional block diagram schematically showing the configuration of the equalization apparatus 100 according to the first embodiment. The equalization apparatus 100 includes a Fourier transform unit 110, an SP transmission line characteristic calculation unit 120, a transmission line characteristic division unit 130, an SP transmission line characteristic distribution calculation unit 140, a desired transmission line characteristic distribution calculation unit 150, A transmission path characteristic extraction unit 160, a transmission path characteristic coupling unit 170, and an equalization unit 180 are provided. The reference numerals in parentheses in FIG. 3 are the configurations in the second and third embodiments.

In the present embodiment, a receiving apparatus (not shown) provided with equalization apparatus 100 receives OFDM symbol SBL in which a GI (Guard Interval) is inserted before a valid symbol as shown in FIG. . Here, as shown in FIG. 4, the effective symbol interval is Tu, the symbol interval is Ts, and the GI length is Tgi. Further, the OFDM symbol SBL is generated by _{performing NDFT} point inverse discrete Fourier transform, and has an SP arrangement as shown in FIG. As shown in FIG. 5, the SP is inserted every 4 symbols in the time direction and inserted every 12 carriers in the frequency direction. The SP is cyclically shifted by 3 carriers for each symbol. In the following embodiments, the above signal is received. Here, the present embodiment is not limited to the received signal, but the SP arrangement needs to be cyclically shifted for each symbol. Further, when the SP arrangement shown in FIG. 5 is used, the transmission path characteristic calculated by SP is 1 in the fluctuation frequency direction in the fluctuation frequency region and the delay time region, as shown in FIG. / 4Ts and a repetition component that cyclically shifts Tu / 12 in the delay time direction, and a repetition component that cyclically shifts Tu / 3 in the delay time direction.

Returning to the description of FIG. 3, the Fourier transform section 110 transforms a received signal including a pilot carrier into a frequency domain signal. For example, the Fourier transform unit 110 performs _NDFT point discrete Fourier transform on the received signal for each symbol to obtain a signal of each carrier.

  The SP transmission line characteristic calculation unit 120 is a transmission line characteristic calculation unit that calculates the transmission line characteristic acting on the pilot carrier based on the frequency domain signal converted by the Fourier transform unit 110. For example, the SP transmission line characteristic calculation unit 120 extracts the SP signal from the signal of each carrier acquired by the Fourier transform unit 110, and divides the signal by a known value, so that the transmission line characteristic acting on the SP (hereinafter, referred to as “SP signal characteristic”). Called SP transmission path characteristics). Then, SP transmission path characteristic calculation section 120 inserts a zero value for a carrier in which a modulated signal in which no SP is arranged exists. Here, the SP transmission path characteristic can be considered as a complex function h (k, l) having a carrier frequency index k and a symbol time index l as variables.

  In the following, the transmission path characteristic, which is a complex function obtained by SP, will be referred to as transmission path characteristics regardless of the conversion of the time axis and the frequency axis.

The transmission line characteristic dividing unit 130 divides the transmission line characteristic calculated by the SP transmission line characteristic calculating unit 120 into components of a plurality of regions on two axes of a variable frequency axis and a delay time axis. For example, the transmission line characteristic dividing unit 130 divides the transmission line characteristic calculated by the SP transmission line characteristic calculating unit 120 into N in the delay time domain and M in the variable frequency domain as shown in FIG. Here, N and M are natural numbers of 2 or more. In addition, it is desirable that the areas divided by the transmission line characteristic dividing unit 130 are arranged symmetrically with respect to the delay time axis. This corresponds to the processing in the two-dimensional Fourier transform unit in Patent Document 1. Similarly to Patent Document 1, when the two-dimensional discrete Fourier transform is used to divide the transmission line characteristics, the transmission line characteristic dividing unit 130 transmits the transmission line of _NDFT points per symbol obtained by the SP transmission line characteristic calculation unit 120. The discrete inverse Fourier transform is performed on the characteristic _MSYM symbol in the carrier frequency domain (in this case, the discrete inverse Fourier transform is performed instead of the discrete Fourier transform in order to make the transformed region have a physical meaning. And a discrete Fourier transform is performed in the symbol time domain, thereby calculating a transmission path characteristic of a complex function having a delay time index of N _DFT points and a variable frequency index of M _SYM points as variables. That is, the transmission path characteristic dividing unit 130 performs N = N _DFT division in the delay time domain and M = M _SYM division in the variable frequency domain. In this case, in the subsequent stage, after the desired transmission line characteristic extraction unit 160 extracts the desired transmission line characteristic, the transmission line characteristic coupling unit 170 performs two-dimensional inverse Fourier transform, that is, discrete Fourier transform in the delay time domain, and in the variable frequency domain. By performing the discrete inverse Fourier transform, it is possible to calculate the transmission path characteristic of the _MSYM symbol used for distortion compensation in the equalization unit 180. In FIG. 7, reference numeral 702 is a desired component, and reference numeral 802 is an unnecessary repetitive component.

Further, the transmission line characteristic dividing unit 130 may perform division of the delay time region or the variable frequency region using a plurality of filters.
2. Description of the Related Art Conventionally, a technique for obtaining transmission line characteristics of modulation data other than SP by filtering transmission line characteristics obtained by SP in a carrier frequency direction and a symbol time direction is known. Here, the filter in the carrier frequency direction has a pass band in the delay time domain, and the filter in the symbol time direction has a pass band in the variable frequency domain.

  Therefore, the transmission line characteristic dividing unit 130 calculates the transmission line characteristic obtained by the SP using N carrier frequency direction filters whose passbands are adjacent and M symbol time direction filters whose passbands are adjacent. Thus, as shown in FIG. 7, the SP transmission path characteristics can be divided into N in the delay time domain and M in the variable frequency domain. In this case, N × M divided transmission path characteristic information is obtained at each signal point defined by the carrier frequency index k and the symbol time index l. In other words, N × M complex functions having carrier frequency index k and symbol time index l as variables are obtained. In this case, in the subsequent stage, after the desired transmission line characteristic extraction unit 160 extracts the desired transmission line characteristic, the transmission line characteristic combination unit 170 uses the N × M points for each carrier frequency index k and each symbol time index l. The transmission path characteristics used for distortion compensation in the equalization unit 180 can be calculated by adding and combining the divided transmission path characteristics information.

  Further, the transmission line characteristic dividing unit 130 may perform division processing by combining Fourier transform and a filter. Specifically, the transmission path characteristic dividing unit 130 performs division in the delay time domain by performing Fourier transform on the carrier direction, and performs filtering processing on the symbol time direction to perform fluctuations. Division in the frequency domain can be performed. This will be described in detail below.

  First, transmission path characteristic dividing section 130 performs M division in the variable frequency domain by applying M symbol time direction filters to the transmission path characteristics of a plurality of symbols calculated by SP.

ここで、ｈ（・）は、ＳＰで算出された伝送路特性である。ｋは、キャリア周波数インデックスである。ｌは、シンボル時間インデックスである。ａ_ｍは、第ｍのシンボル時間方向フィルタのフィルタ係数である。ｇ_ｍ（・）は、第ｍのシンボル時間方向フィルタの処理結果である。 When an FIR filter is used as the mth (1 ≦ m ≦ M) symbol time direction filter, the transmission path characteristic dividing unit 130 performs filter processing according to the following equation (1).

Here, h (•) is a transmission path characteristic calculated by SP. k is a carrier frequency index. l is the symbol time index. a _m is a symbol filter coefficient of the time-direction filter of the m. g _m (•) is the processing result of the m-th symbol time direction filter.

Here, an example of the passband of each filter is shown in FIG. It can be seen that the section between the maximum fluctuation frequency fd _max and the minimum fluctuation frequency fd _min is divided into M parts. In the subsequent stage, in order to combine the filter outputs after extracting the desired transmission path characteristics, it is desirable to set the coefficients so that the sum of the first to M symbol filter characteristics is constant. By using the symbol time direction filter having the above characteristics, as shown in FIG. 9, on the delay time axis and the variable frequency axis, transmission path characteristics corresponding to the region divided into M in the variable frequency direction can be obtained. In FIG. 9, reference numeral 703 is a desired component, and reference numeral 803 is an unnecessary repetitive component.

Next, as shown in the following equation (2), the transmission path characteristic dividing unit 130 performs N = N _DFT point inverse Fourier transform on the carrier frequency for each of the outputs of the M symbol time direction filters. Thus, each of the transmission path characteristics divided into M in the variable frequency region can be divided into N with a delay time.

ここで、ｆ_ｍ（・）は、第ｍのシンボル時間方向フィルタ結果ｇ_ｍ（・）をキャリア逆フーリエ変換した結果である。τは、遅延時間インデックスである。

Here, f _m (•) is the result of carrier inverse Fourier transform of the m-th symbol time direction filter result g _m (•). τ is a delay time index.

Through these processes, the transmission path characteristic f _m (•) for each filter index m corresponding to the delay time index τ and the fluctuation frequency can be calculated for each symbol (l).

Here, as the division number M, a value predetermined by the transmission path to be supported is used. By increasing the number of divisions, it becomes possible to control a finer band, and it is possible to suppress the unnecessary component by separating in detail the desired component of the transmission path characteristics and the unnecessary component such as repetition and Gaussian noise. In addition, fd _max and fd _min may be set in advance according to the assumed amount of time variation of the transmission path.

  As described above, either the Fourier transform or the filter processing is used as the method of dividing the transmission line characteristic obtained by the SP transmission line characteristic calculation unit 120 into N divisions in the delay time domain and M divisions in the variable frequency domain. May be. Further, the filtering process and the Fourier transform process may be performed in the reverse order. Furthermore, division may be performed by performing filter processing in the carrier frequency direction and performing Fourier transform in the symbol time direction.

Also, the transmission line characteristic dividing unit 130 divides a component in a predetermined region (section) including a desired component of the transmission line characteristic among the transmission line characteristics obtained by the SP transmission line characteristic calculation unit 120. .
For example, in the case of the SP arrangement as shown in FIG. 5, as shown in FIG. 1, a repetitive component in the delay time direction is generated at a period of Tu / 3. For this reason, a region (section) having a width Tu / 3 containing only the desired component is divided by the transmission path characteristic dividing unit 130. Note that the transmission path characteristic dividing unit 130 may divide a region (section) exceeding Tu / 3 and perform processing such that a component in the region exceeding Tu / 3 takes a zero value. Alternatively, in the environment where the assumed delay time (Td) is smaller than Tu / 3, the transmission line characteristic dividing unit 130 may divide the region having a width of Td and set the remaining regions to zero values. Further, when a delay wave (preceding wave) exists in a region where the delay time is negative, the transmission path characteristic dividing unit 130 may shift the region to be divided in the negative direction.
In addition, as shown in FIG. 2, the repetitive component in the fluctuation frequency direction appears in a period of ¼ Ts, and when the fluctuation frequency spread is large, the influence from the adjacent repetitive component exceeds ± 1/2 Ts. Receive. Since the present embodiment discriminates and removes the spread of the fluctuation frequency exceeding ± 1 / 2Ts, it is necessary to perform division in a range larger than ± 1 / 2Ts (a range used for discrimination). In the region exceeding ± 1/4 Ts, even if the fluctuation frequency is small, a repetitive component is generated. Therefore, it is desirable not to include the transmission path characteristic dividing unit 130 in the divided region.

  Returning to the description of FIG. 3, the SP transmission line characteristic distribution calculating unit 140, the desired transmission line characteristic distribution calculating unit 150, and the desired transmission line characteristic extracting unit 160 will be described next. The transmission line characteristic obtained by the transmission line characteristic dividing unit 130 includes unnecessary repetitive components due to the arrangement of SPs. Therefore, it is necessary to extract only the desired component. In the present embodiment, in order to extract the desired component, the power ratio in the region where the delay time due to the statistical properties of the transmission path is equal and the sign of the fluctuation frequency is reversed, and the desired component due to the SP arrangement are 2 Of the transmission line characteristics, the two-dimensional power distribution of a desired component that does not include a repetitive component is estimated using regularity in which the dimensional power distribution is repeated.

  The SP transmission line characteristic distribution calculation unit 140 is a transmission line characteristic distribution calculation unit that calculates physical quantities of components in a plurality of regions divided by the transmission line characteristic division unit 130. For example, the SP transmission line characteristic distribution calculation unit 140 calculates the power of the transmission line characteristic in each divided region divided by the transmission line characteristic division unit 130, and calculates the two-dimensional power distribution in the variable frequency region and the delay time region. To do. Here, the power may be obtained using the transmission path characteristics of each divided region of a plurality of symbols. Note that the SP transmission path characteristic distribution calculating unit 140 may calculate the transmission path characteristic distribution using a value obtained by averaging the amplitude or the amplitudes of a plurality of symbols instead of the power. In the following, the SP transmission path characteristic distribution calculation unit 140 may perform calculation using amplitude instead of power. In other words, the physical quantity calculated by the SP transmission line characteristic distribution calculating unit 140 may be power or amplitude.

  Furthermore, the SP transmission path characteristic distribution calculating unit 140 may calculate the physical quantity in consideration of the superimposed noise component. For example, the SP transmission path characteristic distribution calculating unit 140 calculates the physical quantity of the noise component by calculating the physical quantity of the component in the area selected from the components in the plurality of areas divided by the transmission path characteristic dividing unit 130. Then, the calculated physical quantity of the noise component may be subtracted from the physical quantity of the components of the plurality of regions divided by the transmission path characteristic dividing unit 130. More specifically, first, the SP transmission path characteristic distribution calculating unit 140 is a region where the power value is the smallest, or a region where the power value is smaller than a predetermined threshold, that is, a divided region where neither a desired component nor a repeated component exists. Is obtained as noise power. Thereafter, the SP transmission line characteristic distribution calculation unit 140 subtracts the noise power from the power value obtained for the transmission line characteristic of each divided region, thereby obtaining the two-dimensional power distribution of the transmission line characteristic not including the noise component. It is possible to calculate and use the two-dimensional power distribution of the transmission line characteristics not including the noise component for the subsequent processing. This utilizes the fact that the detected power value is the addition of both because the noise component and the transmission path characteristic have no correlation. As described above, the two-dimensional power distribution of the desired component can be accurately obtained even in an environment where the noise is large.

  The desired transmission line characteristic distribution calculation unit 150 uses the transmission line characteristic distribution calculated by the SP transmission line characteristic distribution calculation unit 140 to obtain a distribution of a desired component that does not include a repetitive component of the transmission line characteristic. For example, the desired transmission path characteristic distribution calculation unit 150 calculates the physical quantity of the repetitive component of the transmission path characteristic calculated by the SP transmission path characteristic calculation unit 120 from the physical quantity calculated by the SP transmission path characteristic distribution calculation unit 140. Reduction is performed using the regularity of the component distribution and the statistical properties of the desired component of the transmission path characteristic calculated by the SP transmission path characteristic calculation unit 120, and the physical quantity of the desired component is calculated. More specifically, the desired transmission path characteristic distribution calculation unit 150 has a delay time in which the physical quantity calculated by the SP transmission path characteristic distribution calculation unit 140 is determined by the physical quantity of the desired component of the transmission path characteristic and the arrangement of pilot carriers. And the ratio of the physical quantity of the desired component of the transmission path characteristics of the region shifted cyclically at the variable frequency, and the ratio of the physical quantity of the region where the delay time is equal and the sign of the variable frequency is reversed, A relational expression between the physical quantity calculated by the SP transmission path characteristic distribution calculating unit 140 and the physical quantity of a desired component of the transmission path characteristic is calculated, and the SP transmission path characteristic distribution calculating part 140 is calculated using this relational expression. The physical quantity of the desired component of the transmission path characteristic is calculated from the obtained physical quantity. As an example, in the present embodiment, desired transmission path characteristic distribution calculation section 150 calculates a value calculated according to the physical quantity calculated by SP transmission path characteristic distribution calculation section 140 from the area where the physical quantity is calculated. A physical quantity of a desired component of the pilot carrier is calculated by subtracting from a physical quantity of a predetermined cyclically shifted delay time. In the following, this will be described in detail.

  First, the relationship between the two-dimensional power distribution including the repetitive component and the two-dimensional power distribution of the desired component not including the repetitive component will be described with reference to FIGS. 10 and 11.

  FIG. 10 is a schematic diagram illustrating a power distribution including a repetitive component obtained by the SP transmission path characteristic distribution calculation unit 140. FIG. 11 is a schematic diagram illustrating a two-dimensional power distribution of a desired component that does not include a repetitive component that is to be obtained by the desired transmission path characteristic distribution calculation unit 150. 10 and 11, reception on a two-wave rice transmission line with a large fluctuation frequency is assumed. 10 and 11 show the transmission line characteristic dividing unit 130 that divides the Tu / 3 section in the delay time domain by N = 8 and the ± 3 / 16Ts section in the variable frequency domain by M = 3. This is the case. In the assumed transmission path, as shown in FIGS. 10 and 11, in the region where the variable frequency region is divided by M = 3, the region corresponding to the variable frequency including the variable frequency = 0 is unnecessary. In the region corresponding to the band including the maximum value of the absolute value of the fluctuation frequency among the regions on both sides of the region, in other words, the regions where the division is performed, only the desired component is included without including the repetitive component. Desired components and unnecessary repeating components are included.

また、図１１のＰ_ｎは、下記の（４）式で示され、図１１に示されているそれぞれの分割領域の電力値を示す。

さらに、図１０のｒＰ_ｐは、下記の（５）式で示され、図１０に示されているそれぞれの分割領域の電力値を示す。

なお、Ｐ_ｐ、Ｐ_ｎ及びｒＰ_ｐでは、添字が大きいほど、長遅延の到来波に対応する。但し、ｐ_ｐ０よりも先に到来する先行波が存在する場合、遅延時間方向に巡回シフトしていることを考慮すると、添字の大きな成分、例えばｐ_ｐ７が負の遅延時間を持つ到来波、つまり先行波として扱われる。 P _p in FIG. 11 is expressed by the following equation (3), and indicates the power value of each divided region shown in FIG.

Moreover, _Pn of FIG. 11 is shown by following (4) Formula, and shows the electric power value of each division | segmentation area | region shown by FIG.

Further, rP _p in FIG. 10 is expressed by the following equation (5), and indicates the power value of each divided region shown in FIG.

In P _p , P _n, and rP _p , the larger the subscript, the longer the incoming wave corresponds to. However, when there is a preceding wave that arrives before p _p0 , in consideration of the cyclic shift in the delay time direction, an incoming wave having a large subscript, for example, p _p7, having a negative delay time, that is, Treated as a preceding wave.

Further, it is assumed that the region of P _{p is} a region centered on the fluctuation frequency 1 / 8Ts. The P _n region is a region obtained by shifting the P _p region by −1/4 Ts in the direction of the variation frequency, and is also a region obtained by inverting the sign of the variation frequency in the P _p region. Further, the rP _p region is the same region as the P _p region. Here, the P _p region, the P _n region, and the rP _p region are regions corresponding to a variable frequency band in which a desired component of transmission path characteristics and an unnecessary repetitive component may be included. The region sandwiched between the P _p region and P _n the region is likely there included the desired component of the channel characteristics, unnecessary repetition component is a region not included.

ここで、Ｓは、遅延時間方向にＴｕ／１２に巡回シフトする行列である。（７）式は、変動周波数の符号が負の領域を巡回シフトし重畳していることを示している。また、ｐ_ｐｉとｐ_ｎｉとの比をｍ_ｉ（ここでは、ｉは、０≦ｉ＜８を満たす整数）とすると、ｐ_ｎｉをｍ_ｉ×ｐ_ｐｉに置き換えることができるため、下記の（８）式の関係式が導かれる。
ｒＰ_ｐ＝Ｐ_ｐ＋Ｓ×Ｒ×Ｐ_ｐ
＝Ｐ_ｐ＋Ｍ×Ｐ_ｐ
＝（Ｉ＋Ｍ）×Ｐ_ｐ
＝Ｃ×Ｐ_ｐ （８）
ここで、Ｉは、単位行列である。Ｒは、下記の（９）式で算出される。Ｍは、下記の（１０）式及び（１１）式で算出される。Ｃは、下記の（１２）式及び（１３）式で算出される。

Ｍ＝Ｓ×Ｒ （１０）

Ｃ＝Ｉ＋Ｍ （１２）

なお、Ｃは、繰り返し成分を重畳する行列（以下、繰り返し重畳行列と呼ぶ）である。 First, paying attention to the divided region of rp _p4 in FIG. 10 where the repetitive component 804 exists, a power value in which _pn2 is superimposed on the power value p _p4 of the desired component 704 as the power value of the repetitive component 804 is calculated as rp _p4 Is done. Here, since there is no correlation between the desired component 704 and the repeated component 804 that is shifted and superimposed, rp _p4 is detected as the sum of the power values. Similarly, when considering other delay time components, the following relational expressions (6) and (7) are obtained.
rP _p = P _p + S × P _n (6)

Here, S is a matrix that cyclically shifts to Tu / 12 in the delay time direction. Equation (7) indicates that the region where the sign of the fluctuation frequency is negative is cyclically shifted and superimposed. _Further, (here, i is an integer satisfying 0 ≦ i <8) the ratio of _{p pi} and _{p ni m i When,} since it is possible to replace the _{p ni} in _{m i} × _{p pi,} the following ( 8) A relational expression is derived.
rP _p = P _p + S × R × P _p
= P _p + M × P _p
= (I + M) × P _p
= C × P _p (8)
Here, I is a unit matrix. R is calculated by the following equation (9). M is calculated by the following equations (10) and (11). C is calculated by the following equations (12) and (13).

M = S × R (10)

C = I + M (12)

C is a matrix that superimposes repeated components (hereinafter referred to as a repeated superposition matrix).

In addition, _mi is determined by the characteristics of the transmission path, the directivity of the antenna, and the like. For example, in high directivity antennas, when performing mobile reception in Rayleigh Fading may be the m i _{= 1.} In the case of using a highly directional antenna sensitivity with respect to the traveling direction of the receiver, since the biased distribution such fluctuation frequency is positive, in advance, so that m _i takes a value smaller than "1" You just have to decide.

Furthermore, as shown in FIG. 12, the power ratio _mu is calculated in a region where the absolute value of the variable frequency is smaller than a predetermined threshold by increasing the number of divisions in the variable frequency region, and used as the desired power ratio m. May be. Here, since the region where the absolute value of the fluctuation frequency is small is not easily affected by the repetitive component, the power ratio of the region where the sign of the fluctuation frequency of the desired component is reversed can be obtained. Thus, by calculating m according to the radio wave environment, it is possible to adaptively estimate the repetitive component even when the two-dimensional power distribution in the fluctuation frequency region is biased. Further, it is not necessary to calculate m for all symbols, and it is only necessary to obtain m at a time interval that matches the change in the two-dimensional power distribution of the transmission path characteristics.

By determining m in this manner, the repeated superposition matrix C is determined. Then, the desired transmission path characteristic distribution calculation unit 150 calculates a power distribution of a desired component from the power distribution rP _p including the detected repetitive component by calculating the following formula (14) obtained by modifying the formula (8). P _p can be determined.
P _p = C ⁻¹ × rP _p (14)
Here, C ⁻¹ is an inverse matrix of C.

P _n can be calculated by the following equation (15).
P _n = R × P _p (15)

That is, by calculating the inverse matrix of the repeated superposition matrix C to the power value rP _p in the region where the repeated component can be superimposed in the two-dimensional power distribution obtained by the SP transmission path characteristic distribution calculation unit 140, the repeated component is calculated. The power value P _p not included can be obtained. Here, since the inverse matrix C ⁻¹ is a matrix containing many “0” s, it can be processed with a calculation amount proportional to the division number N. In addition, since the same calculation is performed for each component, the calculation can be performed by repeatedly performing processing using a relatively simple arithmetic circuit. Further, when there is no inverse matrix, a pseudo inverse matrix may be calculated.

Further, the inverse matrix C ⁻¹ may be obtained in advance using _mi that corresponds to the assumed radio wave environment. Even when the inverse matrix is adaptively determined according to the radio wave environment, it is not necessary to perform the inverse matrix calculation for each symbol, and the calculation is performed at time intervals according to the change in the two-dimensional power distribution of the transmission path characteristics. That's fine.

Although the description has been made so far specifying the number of divisions, the present embodiment does not limit the number of divisions. If the delay time direction is divided into N, _Pp, rP p, _{P n} becomes a column vector of N, also, R, S, M, I is a matrix of N × N. Further, the cyclic shift matrix S is a matrix that undergoes a Tu / 12 cyclic shift in the delay time direction. A case where the number of divisions in the variable frequency region is increased is shown in the second embodiment.

  As described above, the desired transmission path characteristic distribution calculation unit 150 uses the power value of the desired component in the region corresponding to the fluctuation frequency band in which the absolute value of the fluctuation frequency is equal to or greater than a predetermined value (Pp and Pn in FIG. 11). Is calculated by the above equations (14) and (15). Desired transmission line characteristic distribution calculating section 150 also uses SP transmission line characteristic distribution calculating section 140 for the power value of the desired component in the region corresponding to the variable frequency band in which the absolute value of the variable frequency is smaller than a predetermined value. The power value calculated in is used as it is. As a result, the desired transmission path characteristic distribution calculating unit 150 can obtain the two-dimensional power distribution of the desired component of the transmission path characteristics.

  Based on the physical quantity of the desired component of the transmission path characteristic calculated by the desired transmission path characteristic distribution calculation unit 150, the desired transmission path characteristic extraction unit 160 uses the components of the plurality of regions divided by the transmission path characteristic division unit 130. Then, the component of the region including the desired component of the transmission path characteristic is extracted. For example, the desired transmission line characteristic extraction unit 160 uses the transmission divided by the transmission line characteristic division unit 130 based on the two-dimensional power distribution of the desired transmission line characteristic obtained by the desired transmission line characteristic distribution calculation unit 150. A divided region having a large power value of the desired component is extracted from the road characteristics. More specifically, the desired transmission line characteristic extraction unit 160 has a desired component in a divided region where the power value exceeds a predetermined threshold in the two-dimensional power distribution calculated by the desired transmission line characteristic distribution calculation unit 150. Judge that it exists. Then, the desired transmission path characteristic extraction unit 160 multiplies “1” by the transmission path characteristic of the divided area in which it is determined that the desired component exists among the transmission path characteristics divided by the transmission path characteristic division unit 130. On the other hand, if the power value does not exceed a predetermined threshold in the two-dimensional power distribution calculated by the desired transmission line characteristic distribution calculation unit 150, the desired transmission line characteristic extraction unit 160 does not exist, that is, repeats. It is determined that only a component or a noise component can be present. Then, the desired transmission path characteristic extraction unit 160 multiplies “0” by the transmission path characteristic of the divided area determined that the desired component does not exist among the transmission path characteristics divided by the transmission path characteristic division unit 130. Here, the threshold value may be set according to the size of the assumed noise component. Alternatively, the power value of the region where the power value is the smallest from the two-dimensional power distribution of the SP transmission line characteristics, that is, the divided region where neither the desired component nor the repetitive component exists is defined as the noise power, and the value exceeding the noise power is set as the threshold value. It may be set.

  The transmission line characteristic combining unit 170 combines the components extracted by the desired transmission line characteristic extraction unit 160 to generate a transmission line characteristic in the frequency domain. For example, the transmission line characteristic coupling unit 170 is divided by the transmission line characteristic dividing unit 130 in accordance with the dividing method of the transmission line characteristic dividing unit 130 described above, and the desired component is extracted by the desired transmission line characteristic extracting unit 160. By combining the path characteristics, the transmission path characteristics of each symbol are calculated.

  The equalization unit 180 uses the frequency domain transmission path characteristics generated by the transmission path characteristic coupling unit 170 to compensate for transmission path distortion of the frequency domain signal converted by the Fourier transform unit 110. For example, the equalization unit 180 uses the carrier frequency domain transmission path characteristic calculated by the transmission path characteristic coupling unit 170 for the carrier frequency domain received signal Fourier-transformed by the Fourier transform unit 110 for each corresponding symbol. To compensate for transmission path distortion. Known compensation methods for transmission path distortion include ZF (Zero Forcing) equalization, MMSE (Minimum Mean Square Error) equalization, and the like. Since the transmission path distortion compensation method is a known technique, description thereof is omitted.

  As described above, the equalization apparatus 100 according to Embodiment 1 calculates the two-dimensional power distribution on the delay time axis and the variable frequency axis of the transmission path characteristics, and the delay time is equal and the sign of the variable frequency is reversed. From the power ratio and the regularity in which the two-dimensional power distribution of the desired component is repeated, a region not including the repeated component is estimated, and only the desired component of the transmission path characteristic is extracted. Thereby, even when the time variation of the transmission path is large, accurate equalization can be performed by adaptively estimating the transmission path.

Embodiment 2. FIG.
The second embodiment is a form in which the number of divisions is increased for the calculation method of the desired transmission path characteristic distribution calculation unit 150 shown in the first embodiment.
As shown in FIG. 3, the equalization apparatus 200 according to Embodiment 2 includes a Fourier transform unit 110, an SP transmission line characteristic calculation unit 120, a transmission line characteristic division unit 230, and an SP transmission line characteristic distribution. A calculation unit 140, a desired transmission line characteristic distribution calculation unit 250, a desired transmission line characteristic extraction unit 160, a transmission line characteristic combination unit 170, and an equalization unit 180 are provided. The equalization apparatus 200 according to the second embodiment is different from the equalization apparatus 100 according to the first embodiment in processing in the transmission path characteristic dividing unit 230 and the desired transmission path characteristic distribution calculating unit 250.

  In the first embodiment, assuming that the number of divisions of the variable frequency region is “3” and the region shifted by ¼ Ts in the variable frequency direction is equal to the region where the sign of the variable frequency is inverted, the desired component The two-dimensional power distribution is calculated. In the second embodiment, the relationship between the two-dimensional power distribution of the SP transmission line characteristics and the two-dimensional power distribution of the desired component when the number of divisions is increased is shown. The method of extracting is shown.

The transmission line characteristic dividing unit 230 divides the transmission line characteristic calculated by the SP transmission line characteristic calculating unit 120 in the delay time domain and the variable frequency domain. The transmission line characteristic dividing unit 130 in the first embodiment sets the number of divisions in the variable frequency region to “3”. However, as shown in FIG. 13, the transmission line characteristic dividing unit 230 in the second embodiment The number of divisions in the variable frequency region is “6”. Here, rP _Bp is a region obtained by shifting rP _An by ¼ Ts in the direction of variation frequency, and rP _Ap is a region obtained by shifting rP _Bn by ¼ Ts in the direction of variation frequency. In FIG. 13, reference numeral 705 is a desired component, and reference numeral 805 is an unnecessary repetitive component.
Further, in the second embodiment, it is assumed that the two-dimensional power distribution of the desired component not including the repetitive component to be obtained by the desired transmission path characteristic distribution calculating unit 250 is as shown in FIG. Here, the region of P _Ap is the same region as the region of rP _Ap . The P _Bp region is the same region as the rP _Bp region. The region of P _An is the same region as the region of rP _An . The region of P _Bn is the same region as the region of rP _Bn .

At this time, as in the first embodiment, as shown in FIG. 5, it has 1/4 Ts in the variable frequency direction and Tu / 12 cyclic shift in the delay time direction to have a repetitive component, and the delay time. In consideration of the power ratio in the region where the sign of frequency fluctuation is reversed, the following equations (16) and (17) are obtained.
rP _Ap = P _Ap + S × P _Bn
= P _Ap + S × R × P _Bp
= P _Ap + M × P _Bp (16)
rP _Bp = P _Bp + S × P _An
= P _Bp + S × R × P _Ap
= P _Bp + M × P _Ap (17)
Here, in the power distribution rP _Ap calculated by the SP transmission line characteristic distribution calculation unit 140, a power value in which P _Ap and P _Bp including a desired component are superimposed is detected, and in the power distribution rP _Bp It can also be seen that a power value in which P _Ap and P _Bp are superimposed is detected.

ｒＰ_ｐ＝Ｃ×Ｐ_ｐ （１９）
ここで、各行列は、下記の（２０）式〜（２２）式のように表すことができる。

また、ｒＰ_ｐ及びＰ_ｐは、２Ｎ個の成分を持つ列ベクトルであり、Ｃは、２Ｎ×２Ｎ行列である。 Further, with rP _Ap , rP _Bp , P _Ap , P _Bp , I and M as sub-matrices, the equations (16) and (17) can be expressed as the following equations (18) and (19).

rP _p = C × P _p (19)
Here, each matrix can be expressed as the following equations (20) to (22).

RP _p and P _p are column vectors having 2N components, and C is a 2N × 2N matrix.

Furthermore, the following equation (23) is obtained by modifying equation (19).
P _p = C ⁻¹ × rP _p (23)

The desired transmission line characteristic distribution calculation unit 250 can calculate the power distribution of the desired component by calculating the equation (23), as in the first embodiment. In the region where the fluctuation frequency is negative, the desired transmission path characteristic distribution calculation unit 250 calculates the power distribution of the desired component using the following equations (24) and (25), as in the first embodiment. be able to.
P _An = R × P _Ap (24)
P _Bn = R × P _Bp (25)

  Even when the number of divisions is further increased, the desired transmission path characteristic distribution calculation unit 250 shifts −12 / Tu in the delay time direction and −1/4 Ts in the variable frequency direction for a certain region, and further changes the sign of the variable frequency. Considering the inverted region, the power distribution of the desired component can be calculated by obtaining the relational expression between them in the same manner as described above. In addition, with respect to the division interval in the variable frequency direction, the transmission path characteristic division unit 230 may divide each region so that the regions shifted by −1/4 Ts overlap. Furthermore, the desired transmission path characteristic distribution calculation unit 250 may perform the above inverse matrix calculation only in the region of the variable frequency where the repetitive component can be superimposed in the assumed radio wave environment.

  As described above, the equalization apparatus 200 according to Embodiment 2 calculates the two-dimensional power distribution on the delay time axis and the variable frequency axis of the transmission path characteristics even when the division number M in the variable frequency region is large. Then, from the power ratio in the region where the delay time is equal and the sign of the variable frequency is reversed and the regularity in which the two-dimensional power distribution of the desired component is repeated, the region not including the repetitive component is estimated, and the desired transmission path characteristics are obtained. Only the components can be extracted. Thereby, even when the time variation of the transmission path is large, accurate equalization can be performed by adaptively estimating the transmission path.

Embodiment 3 FIG.
In the present embodiment, the inverse matrix calculation process is reduced with respect to the calculation method of the desired transmission path characteristic distribution calculation unit 150 shown in the first and second embodiments. Further, functions other than the desired transmission path characteristic distribution calculation unit 150 are the same as those in the first embodiment, and thus description thereof is omitted.

  In Embodiments 1 and 2, it is assumed that the power distribution of the desired component can exist over the delay time region Tu / 3, and the desired transmission line characteristic distribution calculation units 150 and 250 perform calculations. In the third embodiment, a method of simplifying the inverse matrix calculation process in consideration of a radio wave environment in which the maximum delay time assumed is shorter than Tu / 3 will be described.

  As shown in FIG. 3, the equalization apparatus 300 according to the third embodiment includes a Fourier transform unit 110, an SP transmission line characteristic calculation unit 120, a transmission line characteristic division unit 130, and an SP transmission line characteristic distribution. A calculation unit 140, a desired transmission line characteristic distribution calculation unit 350, a desired transmission line characteristic extraction unit 160, a transmission line characteristic coupling unit 170, and an equalization unit 180 are provided. The equalization apparatus 300 according to the third embodiment is different from the equalization apparatus 100 according to the first embodiment in the processing in the desired transmission path characteristic distribution calculating unit 350.

In the first embodiment, the desired transmission path characteristic distribution calculation unit 150 performs the calculation _assuming that P _p and P _n have values at all the divided delay times, but the expected maximum delay time is Tu /. A radio wave environment shorter than 3 is conceivable. In such an environment, by setting only the component due to the matrix M out of the repeated superposition matrix C multiplied by the delay time component that constantly takes a zero value of P _p to “0”, the inverse matrix of The amount of calculation can be reduced.

For example, in the equation (8), consider a radio wave environment in which P _p6 and P _p7 constantly take zero values. At this time, the sixth and seventh columns of the repeated superposition matrix C are multiplied by zero values, so there is no problem even if they are replaced with arbitrary values. Therefore, even if the values in the 6th and 7th columns of C are set to zero in order to reduce the amount of calculation, equation (6) holds. However, on the other hand, if the diagonal component is zero, the inverse matrix cannot be obtained. Therefore, only the components caused by M, that is, m ₆ and m ₇ are set to zero values, and the repeated superposition matrix C is set to the following equation (26), thereby reducing the amount of computation of the inverse matrix C ^−1. Can do.

  In this way, the desired transmission path characteristic distribution calculating unit 350 calculates the inverse matrix with the repetition matrix C component corresponding to the delay time that can be ignored in the assumed radio wave environment as a zero value, thereby obtaining the two-dimensional desired component. The amount of calculation for obtaining the power distribution can be greatly reduced.

Embodiment 4 FIG.
In the fourth embodiment, an extraction method that takes into consideration the content ratio of the repetitive components is described with respect to the extraction method of the desired transmission path characteristic extraction unit 160 shown in the first, second, and third embodiments. In the first, second, and third embodiments, the extraction region is determined using only the power distribution obtained by the desired transmission path characteristic distribution calculating units 150, 250, and 350. However, in the fourth embodiment, the desired transmission path characteristic is determined. The distribution calculation unit 460 also uses the power distribution obtained by the SP transmission path characteristic distribution calculation unit 140 to calculate the two-dimensional power distribution of the repetitive component, and based on the ratio of the desired component and the repetitive component in each divided region. Next, determine the extraction ratio of the transmission path characteristics.

  FIG. 15 is a functional block diagram schematically showing the configuration of the equalization apparatus 400 according to the fourth embodiment. The equalization apparatus 400 includes a Fourier transform unit 110, an SP transmission line characteristic calculation unit 120, a transmission line characteristic division unit 130, an SP transmission line characteristic distribution calculation unit 140, a desired transmission line characteristic distribution calculation unit 150, a desired transmission line A transmission path characteristic extraction unit 460, a transmission path characteristic coupling unit 170, and an equalization unit 180 are provided. The equalization apparatus 400 according to the fourth embodiment is different from the equalization apparatus 100 according to the first embodiment in processing in the desired transmission path characteristic extraction unit 460. In the fourth embodiment, SP transmission path characteristic distribution calculating section 140 also provides the calculated transmission path characteristic distribution to desired transmission path characteristic extracting section 460.

  The desired transmission line characteristic extraction unit 460 subtracts the physical quantity of the desired component of the transmission path characteristic from the physical quantity calculated by the transmission path characteristic distribution calculation unit 140 in each of the plurality of regions, thereby repeating the transmission path characteristic repetitive component. The physical quantity of is calculated. For example, the desired transmission line characteristic extraction unit 460 includes a transmission including the power distribution of the desired transmission line characteristic obtained by the desired transmission line characteristic distribution calculation unit 150 and the repetitive component obtained by the SP transmission line characteristic distribution calculation unit 140. Based on the power distribution of the path characteristics, a segment area having a power value of the desired component larger than the power value of the repetitive component is extracted from the transmission path characteristics divided by the transmission path characteristic divider 130.

  Here, since there is no correlation between the desired component and the repetitive component in each divided region, the two-dimensional power distribution of the repetitive component is obtained from the two-dimensional power distribution obtained by the SP transmission path characteristic distribution calculating unit 140. It is obtained by subtracting the two-dimensional power distribution obtained by the transmission line characteristic distribution calculation unit 150 for each divided region. Alternatively, instead of using the two-dimensional power distribution obtained by the SP transmission line characteristic distribution calculation unit 140, the two-dimensional power distribution obtained by the desired transmission line characteristic distribution calculation unit 150 is converted to an integral multiple of 1/4 Ts in the variable frequency direction. The two-dimensional power distribution of the repetitive component may be obtained by shifting the integral multiple of Tu / 12 in the delay time direction.

  Then, in each of the plurality of regions, the desired transmission line characteristic extraction unit 460 performs division by the transmission line characteristic division unit 130 as the ratio of the physical quantity of the desired component of the transmission line characteristic to the physical quantity of the repetitive component of the transmission line characteristic increases. The extraction ratio for extracting the component of the region including the desired component of the transmission path characteristic is increased from the plurality of regions. For example, the desired transmission path characteristic extraction unit 460 may determine the extraction ratio using the power value of the desired component and the power value of the repetitive component in each divided region. At this time, the desired transmission line characteristic extraction unit 460 divides the transmission line obtained by dividing the coefficient close to “1” so that the extraction ratio increases when the power value of the desired component is larger than the power value of the repetitive component. Multiply the characteristics. Further, the desired transmission line characteristic extraction unit 460 transmits the transmission line characteristic obtained by dividing the coefficient close to “0” so that the extraction ratio becomes smaller when the power value of the desired component is smaller than the power value of the repetitive component. Multiply by. The coefficient to be multiplied may be calculated using the ratio or difference between the two, or both. For example, (power value of desired component) / (power value of desired component + power value of repetitive component) may be used. In other words, due to the ratio or difference between the two, or both, the extraction ratio increases (the multiplication coefficient is closer to “1”) as the power value of the desired component is larger than the power value of the repetitive component. do it. On the other hand, due to the ratio or difference between the two, or both, the extraction ratio becomes smaller (the multiplication coefficient is closer to “0”) as the power value of the desired component is smaller than the power value of the repetitive component. That's fine.

  In the first embodiment, the transmission path characteristics of the segmented region where the power value of the desired component is large are extracted. In the case of the transmission path as shown in FIG. 16, the power value of the desired component increases in a region a where the transmission path characteristic of the desired component and the transmission path characteristic of the repetitive component overlap. It will be extracted including repeated components. On the other hand, in the fourth embodiment, the repetition component can be suppressed as much as possible by changing the extraction ratio using both the power value of the desired component and the power value of the repetition component. Even in such a transmission line that cannot completely divide the desired component and the repetitive component, a decrease in equalization accuracy can be suppressed.

  In addition, in the equalization apparatus 400 according to the fourth embodiment, as illustrated in FIG. 17, the repetitive component is superimposed on the desired component in both the positive region a and the negative region b of the fluctuation frequency. Even in this case, the power values of the desired component and the repetitive component can be calculated, and the desired component can be extracted similarly.

  100, 200, 300, 400 Equalizer, 110 Fourier transform unit, 120 SP transmission line characteristic calculation part, 130, 230 transmission line characteristic division part, 140 SP transmission line characteristic distribution calculation part, 150, 250, 350 Desired transmission line A characteristic distribution calculation unit, 160 a desired transmission line characteristic extraction unit, 170 a transmission line characteristic coupling unit, and 180 an equalization unit.

Claims (14)

A Fourier transform unit that converts a received signal including a pilot carrier into a signal in the frequency domain;
Based on the frequency domain signal transformed by the Fourier transform unit, a transmission line characteristic calculation unit for calculating a transmission line characteristic acting on the pilot carrier;
A transmission line characteristic dividing unit that divides the transmission line characteristic calculated by the transmission line characteristic calculation unit into components of a plurality of regions on two axes of a variable frequency axis and a delay time axis;
A transmission path characteristic distribution calculating section that calculates physical quantities of components of a plurality of regions divided by the transmission path characteristic dividing section;
The physical quantity of the repetitive component of the transmission path characteristic calculated by the transmission path characteristic calculation section from the physical quantity calculated by the transmission path characteristic distribution calculation section, the regularity of the distribution of the repetitive component, and the transmission path characteristic calculation section A desired transmission path characteristic distribution calculating unit that calculates the physical quantity of the desired component by using the statistical property of the desired component of the transmission path characteristic calculated in
Based on the physical quantity of the desired component calculated by the desired transmission path characteristic distribution calculating unit, the component of the area including the desired component is extracted from the components of the plurality of areas divided by the transmission path characteristic dividing unit. A desired transmission line characteristic extraction unit,
By combining the components extracted by the desired transmission line characteristic extracting unit, a transmission line characteristic combining unit that generates a transmission line characteristic in the frequency domain;
An equalization unit that compensates for transmission path distortion of the frequency domain signal transformed by the Fourier transform unit using the transmission path characteristic of the frequency domain generated by the transmission path characteristic coupling unit. Equalizing device. The desired transmission path characteristic distribution calculating unit
The physical quantity calculated by the transmission path characteristic distribution calculating unit is the sum of the physical quantity of the desired component and the physical quantity of the desired component in a region that is cyclically shifted in delay time and variable frequency, which is determined by the arrangement of the pilot carriers. And the physical quantity calculated by the transmission path characteristic distribution calculating unit using the ratio of the physical quantities of the regions where the delay times are equal and the sign of the variable frequency is reversed, and the physical quantity of the desired component Is calculated,
The equalization apparatus according to claim 1, wherein the physical quantity of the desired component is calculated from the physical quantity calculated by the transmission path characteristic distribution calculation unit using the calculated relational expression. The desired transmission path characteristic distribution calculating unit
Calculating the ratio between the physical quantity of the component in the first area and the physical quantity of the component in the second area in which the delay time is equal and the sign of the variable frequency is opposite for the first area,
The equalization apparatus according to claim 1 or 2, wherein the value is calculated using the calculated ratio to the physical quantity calculated by the transmission path characteristic distribution calculation unit. The equalization apparatus according to claim 3, wherein the first region is a region in which an absolute value of a fluctuation frequency is smaller than a predetermined threshold value. The desired transmission line characteristic extraction unit includes:
In each of the plurality of regions, the physical quantity of the repetitive component is calculated by subtracting the physical quantity of the desired component from the physical quantity calculated by the transmission path characteristic distribution calculation unit,
In each of the plurality of regions, as the ratio of the physical quantity of the desired component to the physical quantity of the repetitive component is higher, the desired component is included from the components of the plurality of regions divided by the transmission path characteristic dividing unit. The equalization apparatus according to any one of claims 1 to 4, wherein an extraction ratio for extracting a component of a region is increased. The transmission line characteristic distribution calculation unit
By calculating the physical quantity of the component of the area selected from the components of the plurality of areas divided by the transmission path characteristic dividing unit, the physical quantity of the noise component is calculated,
Subtracting the physical quantity of the noise component from the physical quantity of the component of the plurality of regions divided by the transmission path characteristic dividing unit,
The desired transmission path characteristic distribution calculation unit calculates the physical quantity of the desired component using the physical quantity after the physical quantity of the noise component is subtracted. The equalization apparatus described in 1. The equalization apparatus according to any one of claims 1 to 6, wherein the physical quantity is power or amplitude. A Fourier transform process for transforming a received signal including a pilot carrier into a frequency domain signal;
A transmission path characteristic calculation process for calculating a transmission path characteristic acting on the pilot carrier based on the frequency domain signal transformed in the Fourier transform process;
A transmission line characteristic dividing process of dividing the transmission line characteristic calculated in the transmission line characteristic calculation process into components of a plurality of regions on two axes of a variable frequency axis and a delay time axis;
A transmission line characteristic distribution calculating process for calculating physical quantities of components of a plurality of regions divided in the transmission line characteristic dividing process;
From the physical quantity calculated in the transmission path characteristic distribution calculation process, the physical quantity of the repetitive component of the transmission path characteristic calculated in the transmission path characteristic calculation process, the regularity of the distribution of the repetitive component, and the transmission path characteristic calculation process A desired transmission path characteristic distribution calculating process for calculating the physical quantity of the desired component by using the statistical property of the desired component of the transmission path characteristic calculated in
Based on the physical quantity of the desired component calculated in the desired transmission path characteristic distribution calculating process, the component of the area including the desired component is extracted from the components of the plurality of areas divided in the transmission path characteristic dividing process. A desired transmission line characteristic extraction process,
By combining the components extracted in the desired transmission line characteristic extraction process, a transmission line characteristic combining process for generating a frequency domain transmission line characteristic;
An equalization process for compensating for transmission path distortion of the frequency domain signal transformed in the Fourier transform process using the frequency domain transmission path characteristics generated in the transmission path characteristic coupling process. How to equalize. The desired transmission path characteristic distribution calculating process includes:
The physical quantity calculated in the transmission path characteristic distribution calculation process is the sum of the physical quantity of the desired component and the physical quantity of the desired component in a region that is cyclically shifted in delay time and variable frequency, which is determined by the arrangement of the pilot carriers. And the physical quantity calculated in the transmission path characteristic distribution calculation process using the ratio of the physical quantities in the region where the delay times are equal and the sign of the variable frequency is reversed, and the physical quantity of the desired component Is calculated,
The equalization method according to claim 8, wherein the physical quantity of the desired component is calculated from the physical quantity calculated in the transmission path characteristic distribution calculation process using the calculated relational expression. The desired transmission path characteristic distribution calculating process includes:
Calculating the ratio between the physical quantity of the component in the first area and the physical quantity of the component in the second area in which the delay time is equal and the sign of the variable frequency is opposite for the first area,
The equalization method according to claim 8 or 9, wherein the value is calculated using the calculated ratio to the physical quantity calculated in the transmission path characteristic distribution calculation process. The equalization method according to claim 10, wherein the first region is a region in which an absolute value of a fluctuation frequency is smaller than a predetermined threshold value. The desired transmission line characteristic extraction process includes:
In each of the plurality of regions, the physical quantity of the repetitive component is calculated by subtracting the physical quantity of the desired component from the physical quantity calculated in the transmission path characteristic distribution calculation process,
In each of the plurality of regions, as the ratio of the physical quantity of the desired component to the physical quantity of the repetitive component is higher, the desired component is included from the components of the plurality of regions divided in the transmission path characteristic dividing process. The equalization method according to any one of claims 8 to 11, wherein an extraction ratio for extracting a component of a region is increased. The transmission path characteristic distribution calculation process includes:
By calculating the physical quantity of the component of the area selected from the components of the plurality of areas divided in the transmission path characteristic dividing process, the physical quantity of the noise component is calculated,
Subtracting the physical quantity of the noise component from the physical quantity of the components of the plurality of regions divided in the transmission path characteristic division process,
13. The desired transmission path characteristic distribution calculating step calculates a physical quantity of the desired component using a physical quantity after the physical quantity of the noise component is subtracted. The equalization method described in 1. The equalization method according to any one of claims 8 to 13, wherein the physical quantity is power or amplitude.

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