JP2009141740A - Apparatus and method for ici amount estimation, and receiving device employing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a reception characteristic by reducing the effect of inter-carrier-interference that occurs when receiving a multicarrier signal while moving at high speed. <P>SOLUTION: A carrier interference estimating apparatus includes: a frequency domain converting unit for converting a time-domain OFDM signal into a frequency-domain carrier signal; a transmission line estimating unit for estimating a transmission line from the carrier signal for each symbol; an equalization unit for outputting carrier data by equalization from a transmission line frequency characteristic and the carrier signal; an ICI amount estimating unit for estimating the amount of inter-carrier-interference (ICI) that occurs in each carrier from the amount of variation in the transmission line frequency characteristic; a CN estimating unit for estimating a CN from the transmission line frequency characteristic; a combination ratio calculating unit which estimates an instantaneous CN ratio from the ICI amount and the CN and estimates a branch weighting coefficient based thereon; a multiplier for multiplying carrier data of each branch by the branch weighting coefficient calculated; and a combination unit for combining carrier data weighted in accordance with the branch weighting coefficient. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ICI amount estimation apparatus, an estimation method, and an improvement method for improving reception characteristics in consideration of the influence of inter-carrier interference that occurs when a mobile unit receives a multicarrier signal in the field of mobile communication. The present invention relates to a receiving apparatus and a receiving method used.

  In mobile communication, multipath occurs in a transmission path between transmitting and receiving stations due to reflection / diffraction from surrounding buildings. And when a receiving station moves at high speed like the vehicle-mounted radio | wireless terminal etc. which are mounted in a driving | running | working vehicle, a Doppler shift arises in each (arrival wave) of multipath with a movement.

  FIG. 2 is a diagram showing how a moving receiving station receives an incoming wave with a Doppler shift.

FIG. 2 shows a state in which the transmission wave from the stationary transmission station 201 becomes multipath, and each of the two incoming waves is accompanied by different Doppler shifts f _D1 and f _D2 .

  Doppler shift is an orthogonal used in multi-carrier systems, in particular, terrestrial digital broadcasting (ISDB-T) of the broadcasting standard shown in Non-Patent Document 1, and wireless LAN (IEEE802.11a) of the communication standard shown in Non-Patent Document 2. This is a problem in the case of frequency division multiplexing (hereinafter, referred to as OFDM scheme; Orthogonal Division Division Multiplexing), and there is a problem in that interference occurs between carriers due to interference between carriers when receiving multipaths with different Doppler shifts. . Such an interference component due to inter-carrier interference is called an ICI (Inter-Carrier-Interference) component.

  Regarding high-speed mobile reception of OFDM signals, for example, Patent Document 1 proposes a method of calculating the CN ratio of each branch and using this for weighting the received signal of each branch of the diversity antenna.

  FIG. 7 is a block diagram of the diversity receiver in Patent Document 1.

In the diversity receiver in Patent Literature 1, after the signal received by each antenna is FFTed, the CN ratio calculation unit calculates the CN ratio by separately obtaining the carrier power and the noise power for each symbol, The smoothing processing unit averages over several tens of symbols. Then, a weighting coefficient for the received signal of each branch is determined based on the average ratio of the CN ratio between the branches, and maximum ratio combining is performed for each carrier.
ARIB STD-B31 IEEE Std 802.11a-1999 Jean-Paul M.J. G. LINARTZ et al., “New Equalization Approach for OFDM over Dispersive and Rapidly Time Varying Channel” Volume 2, Page: 1375-1379, The 11th IE Int. JP 2006-253915 A

  By the way, in an environment where multicarrier signals are received while moving at high speed, the amount of fluctuation in the transmission path increases as the moving speed increases, and the amount of ICI generated also changes greatly from moment to moment. When multipath fading becomes frequency selective, the amount of ICI generated varies from carrier to carrier. When receiving a multi-carrier signal in such an environment, the diversity receiver shown in Patent Document 1 does not calculate the CN ratio based on the instantaneous ICI amount, resulting in an environment in which the transmission path varies. In FIG. 5, since the weighting between antenna branches cannot be optimized, reception characteristics are not improved.

  Therefore, the present invention solves the problem in receiving multi-carrier signals while moving at high speed, and provides an ICI amount estimation method and estimation device for more accurately obtaining an instantaneous signal-to-noise ratio, and An object of the present invention is to provide a receiving method and a receiving apparatus using the same.

  In order to solve the above-described problems, an ICI amount estimation apparatus according to the present invention includes a transmission path fluctuation estimation unit that calculates a fluctuation quantity of a transmission path frequency characteristic and outputs the transmission path fluctuation characteristic, and a square that squares the transmission path fluctuation characteristic. An arithmetic unit, and a fixed coefficient multiplier that multiplies the output of the square arithmetic unit by a fixed coefficient determined according to a predetermined number of carriers.

  According to the ICI amount estimating apparatus of the present invention, when receiving a multi-carrier signal, the frequency response of the transmission path exhibits frequency selectivity due to the influence of multipath, and further, the transmission path fluctuates at a high speed and the ICI changes. Even under a received radio wave environment, the instantaneous signal-to-noise ratio can be calculated by separating the average carrier signal power, noise power, and instantaneous ICI amount.

  If the ICI amount estimating apparatus of the present invention is used in a receiving apparatus that performs diversity reception, it is possible to optimize the weighting of the received signal of the antenna branch based on the instantaneous signal-to-noise ratio. Also, if used in a receiver that performs error correction, error correction can be performed with a likelihood optimized based on the instantaneous signal-to-noise ratio, so that reception characteristics during high-speed mobile reception can be improved. it can.

  Embodiments of the present invention will be described below. An example of the multi-carrier scheme will be described using the OFDM scheme and the signal format of the ISDB-T scheme shown in Non-Patent Document 1.

(Embodiment 1)
First, the ICI amount estimation method in the present invention will be described using mathematical expressions.

A carrier signal obtained by converting a received signal in the time domain into a frequency domain is expressed as (Equation 1) when an ICI component is included. In (Equation 1), _{Y m} is the m-th of all carriers _{(m = 0~N T -1, N} T: all carriers total) with a carrier _{signal, H m, m} is the transmission channel frequency in the m carrier Characteristic H _{m, n} is a mutual interference characteristic that the m-th carrier receives from the n-th carrier (n = 0 to N _T -1, n ≠ m). The second term on the right-hand side of (Formula 1) is the ICI component, and the m-th carrier receives interference from surrounding carriers other than itself. Z _m is a noise component in the m-th carrier.

When time variation occurs in the transmission path frequency characteristic H, the ICI component loses orthogonality between carriers and becomes an interference component. As shown in Non-Patent Document 3, when the Taylor expansion is performed for the time fluctuation of the transmission line frequency characteristic H and the first fluctuation component is handled, it is approximated as (Equation 2). By this approximation, it is possible to calculate in advance as a coefficient how much a certain carrier leaks into surrounding carriers and causes interference. In (Expression 2), a matrix Ξ (hereinafter referred to as an FFT leak matrix) is a matrix of N _T rows × N _T rows indicating the amount of leakage between carriers (Equation 3). H ′ is a first-order time fluctuation component of the transmission channel frequency characteristic of each carrier, and X is carrier data. T indicates transposition.

  Regarding the temporal variation of the transmission line frequency characteristic H, a secondary variation component or a variation component higher than that may be considered, but here, as an example, a case where only the primary variation component is handled will be specifically described.

Next, the amount of interference I _{m, n} given to the m-th carrier when the n-th carrier is subjected to the time variation of the transmission path is obtained by calculation. Assume that the symbol length of the OFDM symbol is Ts, the guard length is Tg, the effective symbol length is Tu, and the schematic diagram of the OFDM symbol shown in FIG.

When the primary time fluctuation component of the transmission line frequency characteristic in the nth carrier is h _n ′ (t), the ICI amount I _{m, n} is given by

Here, the carrier being interfered m = 0, is generalized interference source carrier as n ≠ m, the interference I _n the first m (= 0) carrier receives from the n (≠ 0) carrier following equation (equation 7).

Therefore, the ICI amount σ _ICI ² received by an arbitrary carrier is obtained by the following formula (formula 8).

Here, the carrier data _Xn to be transmitted has no correlation between carriers due to the randomness of data, the variance is 1, and the first-order fluctuation component of the transmission channel frequency characteristic received by the nth carrier is expressed by (Equation 8). Assuming that h _n ′ = h _m ′, which is representative of the primary time fluctuation component received by the m-th (= 0) carrier, the ICI amount σ _ICI ² received by the m-th (= 0) carrier is as follows.

Then, the ICI amount σ _{ICI, N} ² when receiving interference from N carriers in the vicinity is expressed by the following equation.

  Furthermore, when N is ∞,

It becomes. Here, the primary fluctuation component h _m ′ of the channel frequency characteristic of the m-th carrier is, for example, the channel frequency characteristics H _m [l + 1] and H _m [l−1] estimated from symbols before and after the l-th symbol. ] And the following equation can be obtained.

From (Equation 10) and (Equation 11), it can be seen that the ICI amount σ _ICI ² is proportional to the square of the time-varying component of the transmission path frequency characteristic. Further, the proportionality coefficient is determined by the number of carriers N used for estimating the ICI amount. Here, this is called an occurrence coefficient. Further, the amount of ICI remaining after removing ICI in consideration of N carriers (residual ICI amount) is also in a proportional relationship, and the proportionality coefficient in this case is called a residual coefficient. Table 1 shows the generation coefficient and the residual coefficient according to the number of carriers N considered for the estimation of the ICI amount. However, this is a case where only the primary time fluctuation component of the transmission line frequency characteristic is evaluated.

  An ICI amount estimation apparatus that embodies the above-described ICI amount estimation method is as follows.

  FIG. 4 is a detailed block diagram of the ICI amount estimating apparatus according to Embodiment 1 of the present invention.

  In FIG. 4, an ICI amount estimation apparatus 1 (corresponding to the ICI amount estimation units 113 and 119 in FIG. 1) includes a transmission channel fluctuation estimation unit 400 that estimates a transmission channel fluctuation amount H ′, a square calculation unit 404, and a fixed coefficient. A multiplication unit 405.

  As described above, the ICI amount estimating apparatus according to Embodiment 1 of the present invention has a simple configuration that calculates the amount of time fluctuation of the transmission line frequency characteristic in the transmission line fluctuation amount unit, and multiplies the square value thereof by a fixed coefficient. It can be calculated. As described above, it is best to multiply the square value of the amount of time variation by a fixed coefficient, but the amount of time variation itself may be multiplied by a proportional coefficient determined by the number of carriers N used for estimating the ICI amount.

  The transmission path fluctuation estimation unit includes, for example, a symbol delay unit that delays by a time length Ts of one symbol, and a transmission path fluctuation amount calculation unit that calculates a fluctuation amount from the transmission path before and after the symbol. The fixed coefficient multiplication unit includes an ICI coefficient memory 105 that holds a fixed coefficient based on a generation coefficient determined according to the number of carriers for estimating the ICI amount.

The input of the ICI amount estimation unit 1 is a transmission path frequency characteristic H in the frequency domain represented by (Equation 1). Based on the input transmission line frequency characteristic, a transmission line fluctuation amount H′410 is calculated from the delay unit and the transmission line fluctuation amount calculation unit. Here, the transmission path fluctuation amount is calculated according to (Equation 3). This is squared by the square calculation unit and multiplied by the value stored in the ICI coefficient memory. The ICI coefficient memory, a value based on the generated coefficients and effective symbol length T _u corresponding to the predetermined number N as shown in Table 1 (ICI coefficient of formula 13) is stored.

  As described above, the ICI amount estimation apparatus according to Embodiment 1 of the present invention is characterized in that the ICI amount (power) is estimated with a simple configuration that includes only calculation of transmission path fluctuation characteristics, squaring, and multiplication of a fixed coefficient. To do.

  Note that, in calculating the primary fluctuation amount of the transmission line frequency characteristic, the transmission line fluctuation estimation unit 400, as an example, calculates the first to (l + 1) th symbols and the (l-1) th symbol adjacent to the lth symbol. Although the transmission path fluctuation characteristic H ′ (l) in l symbol is estimated, it may be obtained from the next (l + 2) symbol and the (l−2) symbol in the next adjacent, and the calculation method and calculation of the transmission path fluctuation characteristic. Any symbol number can be used.

  In addition, the transmission line fluctuation characteristics are specifically shown for the case of handling up to the primary fluctuation component as an example, but may be obtained in consideration of the secondary fluctuation component and higher fluctuation components.

  Next, a diversity receiving apparatus will be described as an example of a receiving apparatus that includes the ICI amount estimating apparatus and improves reception characteristics during high-speed mobile reception.

  FIG. 1 is a block diagram of a diversity receiving apparatus including an ICI amount estimating apparatus according to Embodiment 1 of the present invention.

  In FIG. 1, a diversity receiving apparatus receives RF waves of a desired channel and converts RF (Radio Frequency) band received signals into basebands, and A / Ds that convert analog signals into digital signals. Units 103 and 108, symbol synchronization units 104 and 109 that perform OFDM symbol synchronization processing, guard removal units 105 and 110 that remove guard intervals included in the OFDM symbol, and time domain OFDM signals as frequency domain carrier signals The frequency domain conversion units 111 and 117 for converting to 150 and 151, the transmission channel estimation units 112 and 118 for estimating the transmission channel frequency characteristic from the carrier signals 150 and 151, and the carrier signal using the transmission channel frequency characteristic. Equalizing section 115 for equalizing and outputting carrier data 121, ICI amount estimating sections 113 and 119 (same as ICI amount estimating apparatus 1 in FIG. 4) for estimating the ICI amount generated in each carrier signal from the variation amount of the transmission channel frequency characteristic, carrier data and transmission channel frequency characteristic CN estimation unit for estimating carrier power and noise power from the above, and a combination ratio calculation for estimating instantaneous CN from ICI amount, carrier power and noise power, and calculating a branch weight coefficient for the received signal of each branch based on this Unit 123, multipliers 116 and 122 that multiply the calculated branch weight coefficient by the carrier data of each branch, and a combiner 124 that combines carrier data weighted by the branch weight coefficient. Note that, for example, FFT calculation is used for the conversion from the time domain signal to the frequency domain signal in the frequency domain conversion units 111 and 117.

  Since the parts other than the part for obtaining the ICI amount by the ICI amount estimating units 113 and 119 and the part for calculating the branch weight coefficient based on the ICI amount are well known as receiving apparatuses for demodulating OFDM signals, the detailed operation description is omitted.

  First, as described in the first embodiment, the ICI amount is estimated by the ICI amount estimation units 113 and 119. Next, average carrier power C and noise power N are calculated by CN estimating sections 114 and 120 for each carrier. For example, the carrier power C is obtained by averaging a square value of the amplitude of the transmission path frequency characteristic for a predetermined interval, and the noise amount N is, for example, a pilot carrier or TMCC (Transmission A and Multiplexing Configuration and Control) carrier MER (Modulation Error). (Rate) value is obtained by averaging predetermined intervals. A known method is used as an average calculation method of C and N.

Then, the combination ratio calculation unit 123 calculates a branch weight coefficient using the obtained ICI amount, the carrier power C, and the noise power N. When the average carrier power, average noise power, and ICI amount of the n-th carrier and the k-th branch are C _{n, k} , N _{n, k} and σ ² _{ICI (n, k)} , respectively, instantaneous CN _{n, k} is _{expressed as} 14).

Then, the weight coefficient W _{n, k} (k = 1, 2) of the nth carrier and the kth branch is obtained according to the following equation.

The branch weight coefficient W _{n, k} is multiplied by the carrier data X _{n, k} after equalization by the multipliers 116 and 122 and synthesized by the synthesis unit 124. The combined carrier signal X _{C (n)} follows the following formula.

Since the combined carrier signal X _C calculated in this way is synthesized by calculating the branch weight coefficient based on the instantaneous ICI amount, the inter-branch signal is obtained by the synthesis method based on the average CN ratio. Since the combination ratio (branch weight coefficient) accurately reflects the difference in quality, reception characteristics can be improved.

As described above, the reception apparatus including the ICI amount estimation apparatus according to Embodiment 1 of the present invention estimates the instantaneous ICI amount in addition to the calculation of the average carrier power and noise power in the diversity reception. Is considered as noise, and a more appropriate branch weight coefficient is calculated. Note that the branch weight coefficient W _k conforms to (Equation 15), but may be any value that reflects the instantaneously calculated ICI amount. With respect to the instantaneous ICI amount estimation method, the ICI amount depends on the magnitude of the temporal variation of the transmission line frequency characteristic, and therefore, any estimation method based on this may be used, and not the ICI amount estimation method.

  In addition, as a carrier combining method for diversity, the carrier data after equalization is weighted (Equation 16). However, the present invention is not limited to this, and known diversity such as weighting the carrier signal before equalization is used. A synthesis method may be used.

  Further, the ICI amount estimating apparatus and the diversity receiving apparatus including the same according to Embodiment 1 of the present invention can be applied if the target is a multicarrier signal, and the signal format such as DVB-T can be used regardless of the signal format. Even if applicable.

(Embodiment 2)
Next, another application example of the ICI amount estimation apparatus according to the present invention will be described. Normally, error correction is performed based on data reliability, such as likelihood in soft decision Viterbi decoding. Therefore, an embodiment will be described in which the estimation result of the ICI amount is used for the reliability of carrier data at the time of decoding.

  FIG. 5 is a block diagram of a receiving apparatus according to the second embodiment.

  A frequency domain transform unit 601, a transmission path estimation unit 602, an equalization unit 606, a CN estimation unit 603, an ICI amount estimation unit 604, a data determination unit 607, a multiplier 608, and an error correction unit 609 Including. Among these, the components other than the carrier weighting coefficient calculation unit 605 and the error correction unit 609 are the same as those in the first embodiment.

The data determination unit 607 performs 0 or 1 data determination for each data bit based on the signal point arrangement corresponding to the modulation method. Here, a case will be described in which the modulation scheme is QPSK (Quadrature Phase Shift Keying) and modulation is performed with a signal point arrangement as shown in FIG. As shown in FIG. 6, the data B to be transmitted is mapped to the signal points S1 to S4 in FIG. 6 according to the data series every 2 bits. Then, on the receiving side, demapping is performed according to the signal point. Specifically, when the carrier data X is in the first quadrant, (D ₀ , D ₁ ) = (− 1, −1), and when the carrier data X is in the second quadrant, (D ₀ , D ₁ ) = ( −1, 1), (D ₀ , D ₁ ) = (1, 1) when in the third quadrant, (D ₀ , D ₁ ) = (1, −1) when in the fourth quadrant Is determined. The carrier weighting coefficient calculation unit calculates the instantaneous CN based on the instantaneous ICI amount estimated for each carrier. If the instantaneous CN of the n-th carrier is CN _n , the instantaneous CN calculated based on (Equation 17) is obtained.

The calculated instantaneous CN _n is weighted by the multiplier 608 with respect to the determination data of the nth carrier. Specifically, when the modulation method is QPSK, the determination data of the nth carrier is D _{n, p} (pε0, 1), and weighting is performed based on (Equation 18).

  By this weighting process, when the amount of ICI is large and the reliability of the carrier is low, the likelihood of the determination data of the carrier is lowered. Conversely, when the reliability is high, the likelihood of the determination data of the carrier is increased.

  Then, the error correction unit 609 performs a decoding process using the weighted determination data D ′ as an input. For example, when the transmission data is encoded with a convolutional code, a Viterbi decoding process is performed. Since the convolutional code and Viterbi decoding are well known, the description thereof is omitted.

  As described above, the receiving apparatus according to Embodiment 2 of the present invention reflects the estimation result of the ICI amount on the reliability of each carrier. Since this is used for the likelihood at the time of decoding, it can decode with more reliable reliability. Although the carrier weighting coefficient conforms to (Equation 17), any carrier weighting coefficient that reflects the ICI amount calculated instantaneously may be used. With respect to the instantaneous ICI amount estimation method, the ICI amount depends on the magnitude of the temporal variation of the transmission line frequency characteristic, and therefore, any estimation method based on this may be used, and not the ICI amount estimation method.

  In this embodiment, convolutional code is used for encoding and Viterbi decoding is used for decoding. However, the present invention is applicable to error correction methods based on likelihood such as turbo code and LDPC (Low Density Parity Code).

  Further, although the case of QPSK as a subcarrier modulation method has been described, other digital modulation methods such as BPSK, 16QAM, 64QAM, and 256QAM may be used.

  Furthermore, the receiving apparatus according to Embodiment 2 of the present invention can be applied if the target is a multicarrier signal, and can be applied to a signal format such as DVB-T regardless of the signal format.

  An ICI amount estimating method and a receiving method and receiving apparatus using the same according to the present invention estimate inter-carrier interference that occurs when a multicarrier signal is received by high-speed mobile reception, and use this to demodulate antenna diversity reception and error correction processing. By using it for processing, it is possible to improve reception characteristics. Therefore, it is useful for a receiving device that is mounted on a vehicle or train that travels at high speed, or that is carried by a passenger and receives an OFDM signal such as terrestrial digital broadcasting while moving.

FIG. 3 is a block diagram of a receiving apparatus using the ICI amount estimating unit apparatus in Embodiment 1 of the present invention Diagram showing how a moving receiving station receives an incoming wave with a Doppler shift Schematic diagram of OFDM symbol The block diagram of the ICI amount estimation part in Embodiment 1 of this invention The block diagram of the receiver using the ICI amount estimation part apparatus in Embodiment 2 of this invention Schematic diagram showing the relationship between signal point arrangement of QPSK modulation and determination data Block diagram of diversity receiver shown in Patent Document 1

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ICI amount estimation apparatus 101,106 Antenna 103,108 RF part 104,109 Symbol synchronization part 105,110 Guard removal part 111,117 Frequency domain conversion part 112,118 Transmission path estimation part 113,119 ICI amount estimation part 114,120 CN estimating section 115, 121 equalizing section 116, 124 multiplier 123 combining ratio calculating section 124 combining section 201 transmitting station 202 mobile receiving station 400 transmission path fluctuation estimating section 401, 402 symbol delay unit 403 transmission path fluctuation amount calculating section 404 square Calculation unit 405 Fixed coefficient multiplication unit 801, 814 Antenna 802, 815 FE unit 803, 816 FFT unit 804, 817 Division unit 805, 818 Pilot pattern 806, 819 IFFT unit 807, 820 Transmission path estimation unit 808, 821 CN ratio calculation unit 827 1 weight calculator 828 combining unit 829 demaps

Claims (9)

An ICI amount estimation device that is included in a multicarrier signal receiver and estimates an ICI amount in a carrier signal, and calculates a variation amount of a transmission channel frequency characteristic and outputs a transmission channel variation characteristic. And a fixed coefficient multiplier for multiplying the transmission path fluctuation characteristic by a fixed coefficient determined according to a predetermined number of carriers, and estimating the ICI amount for each carrier based on the transmission path fluctuation characteristic A feature of the ICI amount estimating apparatus. 2. The ICI amount estimation apparatus according to claim 1, wherein the transmission path fluctuation estimation unit estimates a first-order fluctuation amount of a transmission path frequency characteristic as the transmission path fluctuation characteristic. The ICI amount estimating apparatus further includes a square calculation unit that squares the transmission path fluctuation characteristic, and multiplies the value obtained by squaring the transmission path fluctuation characteristic by the fixed coefficient determined according to a predetermined number of carriers. The ICI amount estimation apparatus according to claim 1. 2. The ICI amount estimating apparatus according to claim 1, wherein the multicarrier signal is an OFDM signal. A reception device that receives a multicarrier signal using the ICI amount estimation device, and a plurality of antennas, a frequency domain conversion unit that converts a reception signal in a time domain of each branch into the carrier signal in a frequency domain, A channel estimation unit that estimates channel frequency characteristics from a carrier signal, an equalization unit that equalizes carrier signals based on the channel frequency characteristics and outputs carrier data, and estimates carrier power and noise power A CN estimation unit, a combination ratio calculation unit that calculates a branch weighting coefficient for the carrier signal in each branch from the carrier power and noise power of each branch, and the ICI amount estimated by the ICI amount estimation device; A multiplier that multiplies the carrier data of each branch by the branch weighting coefficient, and a weighted carrier of each branch A synthesizing unit for synthesizing over data, the receiving apparatus when the carrier signal of each branch is characterized in that for decoding the signals are weighted and combined based on ICI amount for each carrier. A receiving device for receiving a multicarrier signal using the ICI amount estimating device, a frequency domain converting unit for converting a time domain received signal into a frequency domain carrier signal, and estimating a transmission channel frequency characteristic from the carrier signal A channel estimation unit, an equalization unit that equalizes carrier signals based on the channel frequency characteristics and outputs carrier data, a data determination unit that performs data determination on the carrier data and outputs determination data, A CN weighting unit that estimates carrier power and noise power from the carrier data and the channel frequency characteristics, and carrier weighting from the carrier power, the noise power, and the ICI amount estimated by the ICI amount estimating device. A carrier weighting coefficient calculating unit for calculating a coefficient; and a multiplier for multiplying the determination data by a carrier weighting coefficient. Te, receiving apparatus, characterized in that the error correction determination data weighted based on ICI amount for each carrier. The receiving apparatus according to claim 5 or 6, wherein the multicarrier signal is an OFDM signal. A method for estimating an ICI amount in a carrier signal, the step of estimating a fluctuation amount of a transmission path frequency characteristic, a step of squaring the transmission path fluctuation characteristic, and a square value of the transmission path fluctuation characteristic according to a predetermined number of carriers Multiplying a fixed coefficient determined by the ICI amount estimation method. 9. The ICI amount estimating method according to claim 8, wherein a primary fluctuation amount of a transmission line frequency characteristic is estimated as the transmission line fluctuation characteristic.

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