JP5511433B2 - Receiver - Google Patents

Description

  The present invention relates to a receiver for multicarrier communication using distributed pilots.

  In multicarrier communication using distributed pilots, a method using two-dimensional Wiener Filtering has been proposed as a method for estimating a transmission path theoretically optimally from distributed pilots (see Non-Patent Document 1).

  In this method, first, on the two-dimensional plane represented by the distance in the frequency direction (number of subcarriers) weighted by the delay spread of the transmission line and the distance in the time direction (symbol) weighted by the Doppler frequency, N pilot components are selected in ascending order of distance from the subcarrier symbol component whose estimated value is to be obtained. Then, the transmission path estimation value in the N pilot components (the pilot signal is known between the transmitter and the receiver, so the received signal is subjected to FFT (Fast Fourier Transform), and the pilot component is divided by the transmission symbol to thereby transmit the transmission path. An estimation value is obtained), a distance between the subcarrier symbol for which the transmission path estimation value is to be obtained and the N pilot components (distance on the two-dimensional plane described above), and a correlation matrix obtained from the signal-to-noise power ratio, The desired transmission path estimated value is obtained by multiply-adding the true value of the transmission path gain and the N × 1 weighting coefficient vector calculated so as to minimize the square error of the transmission path estimation value.

  In addition, as a conventional transmission path estimation method in multicarrier communication using distributed pilots, the transmission path delay spread and Doppler frequency are estimated from the received signal, and the transmission path delay spread estimated by the estimation means and There is a method for determining a method for interpolating a channel estimation value of a data component located between distributed pilot components included in a received signal from a Doppler frequency, and performing a channel estimation using the determined interpolation method. It has been proposed (see Patent Document 1 below).

JP 2009-260604 A

Peter Hoeher, Stefan Kaiser, Patrick Robertson, “Two-Dimensional Pilot-Symbol-Aided Channel Estimation by Wiener Filtering,” in Proc. IEEE ICASSP '97, pp.1845-1848, April 1997.

  The transmission path estimation technique disclosed in Non-Patent Document 1 requires an inverse matrix operation in order to calculate a theoretically optimal weighting coefficient vector for all subcarrier symbol components. There was a problem that it was difficult to implement.

  Further, in Patent Document 1 described above, a mobile station apparatus that has means for determining an interpolation method and performs transmission path estimation using the method determined by this means has been disclosed. There is no description. That is, no consideration is given to the reduction in the amount of computation in the transmission path estimation process.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a receiving apparatus that reduces the amount of calculation compared to the prior art and performs transmission path estimation with high accuracy.

  In order to solve the above-described problems and achieve the object, the present invention is a multicarrier signal receiving apparatus in which a pilot signal is periodically arranged for each frame of a predetermined number of symbols, and a replica of a pilot signal Replica generating means for generating a transmission line gain calculating means for multiplying each received pilot signal in the frame by the complex conjugate of the replica, and calculating a transmission line gain at each pilot signal position indicated by time and frequency, Based on the received signal, parameter generation means for generating one or more transmission path parameters indicating the transmission path state, and calculation of a transmission path estimation value in a specific transmission path state for each position where no pilot signal is arranged Information on the estimated channel position of the pilot signal position used in and each transmission indicated by the information When one or more tables in which weighting coefficients for weighting the estimated values are registered are stored and a transmission path parameter is input from the parameter generation means, it corresponds to the transmission path state indicated by the transmission path parameter. Transmission for calculating a transmission line estimation value at each signal position based on a table management means for outputting a table, a transmission line gain calculated by the transmission line gain calculation means, and a table output from the table management means And a path estimation means.

  According to the present invention, it is possible to perform transmission path estimation only by a product-sum operation, and it is possible to reduce the amount of calculation.

FIG. 1 is a diagram illustrating a configuration example of a first embodiment of a receiving device according to the present invention. FIG. 2 is a diagram illustrating a configuration example of the frequency domain processing unit according to the first embodiment. FIG. 3 is a diagram illustrating an example of a frame configuration of an OFDM signal. FIG. 4 is a diagram for explaining a weighting coefficient table held by the weighting table unit. FIG. 5 is a diagram illustrating a configuration example of a frequency domain processing unit according to the second embodiment. FIG. 6 is a diagram illustrating a configuration example of a communication system according to the third embodiment. FIG. 7 is a diagram illustrating an example in which spatial multiplexing is performed using a plurality of leaky coaxial cables and a plurality of reception antennas in the third embodiment.

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

Embodiment 1 FIG.
In the present embodiment, as an example, a receiving apparatus for OFDM (Orthogonal Frequency Division Multiplexing) communication using distributed pilots will be described.

  FIG. 1 is a diagram illustrating a configuration example of a first embodiment of a receiving device according to the present invention. The receiving apparatus of the present embodiment includes an antenna 1 that receives a multicarrier signal, an analog unit 2 that converts a radio frequency (RF) signal S11 received by the antenna 1 into a baseband analog signal S21, and an input base AD converter 3 that converts the band analog signal S21 into a birthband digital signal S31, a time domain processing unit 4 that removes a GI (Guard Interval) from the burstband digital signal S31, and a GI output from the time domain processing unit 4 An FFT unit 5 that converts the removal time signal S41 into a frequency signal S51, a frequency domain processing unit 6 that performs signal processing to be described later on the frequency signal S51 to generate a demodulated soft decision bit sequence S61, and a demodulated soft decision bit An error correction decoding unit 7 that performs error correction processing on the sequence S61 to generate a decoded bit sequence S71; Prepare.

  In the receiving apparatus having such a configuration, the frequency domain processing unit 6 performs characteristic processing to estimate a transmission path with high accuracy with a smaller amount of computation than in the past.

  FIG. 2 is a diagram illustrating a configuration example of the frequency domain processing unit 6. As illustrated, the frequency domain processing unit 6 includes a pilot separation unit 61, a replica generation unit 62, a replica multiplication unit 63, a transmission path parameter estimation unit 64, a table selection unit 65, a weighting table unit 66, a transmission path estimation unit 67, A transmission path equalization unit 68 and a demapping unit 69 are provided.

  The pilot separation unit 61 separates the frequency signal S51 input from the FFT unit 5 into a data symbol component (data signal S611) and a pilot symbol component (pilot signal S612).

  The replica generation unit 62 generates a replica of the pilot symbol component, and the replica multiplication unit 63 (corresponding to transmission path gain calculation means) multiplies the pilot signal S612 by the replica (signal S621) to thereby transmit the transmission path gain of the pilot component. S631 is generated.

  A transmission path parameter estimation unit 64 (corresponding to parameter generation means) generates an estimated transmission path parameter S641 based on the frequency signal S51.

  The table selection unit 65 generates a table selection signal S651 based on the estimated transmission path parameter S641.

  The weighting table unit 66 holds one or more weighting coefficient tables, selects one of the held tables based on the table selection signal S651, and outputs it as a table value S661. The weighting table unit 66 and the table selection unit 65 constitute table management means.

  The transmission path estimation unit 67 performs transmission path estimation based on the transmission path gain S631 of the pilot component and the table value S661, and outputs the estimation result as a transmission path estimation value S671.

  The transmission path equalization unit 68 generates the equalized data signal S681 based on the transmission path estimation value S671 and the data signal S611.

  The demapping unit 69 demaps the equalized data signal S681 to generate a demodulated soft decision bit sequence S61.

  Here, details of the weighting table unit 66 will be described. The weighting table unit 66 includes T types (T is an integer of 1 or more) of weighting coefficient tables 66-t (0 ≦ t ≦ T−1).

  Each weighting coefficient table 66-t includes the following two types of components (k, l) (0 ≦ k ≦ 31, 0 ≦ l ≦ 15) in total of 16 symbols and 32 subcarriers. The values (A and B) are described for M pilots (0 ≦ M ≦ 31) used for estimation. As the number of pilots M used for estimation increases, the estimation accuracy increases, but the amount of computation increases accordingly. For convenience, this embodiment will be described assuming that M = 4.

A: Coordinates (K, L) of pilot symbols used for transmission path estimation
(K and L are the coordinates of the place where the pilot symbol is inserted)
B: Weight of pilot symbol of A used for channel estimation (weight of pilot symbol corresponding to A)

  The selection method of A and the calculation method of B are described as follows in Non-Patent Document 1 shown above.

<How to select A>
On a two-dimensional plane in the subcarrier direction and the OFDM symbol direction, a predetermined number (M) of pilots are selected in order from the pilot closest to the (k, l) component whose transmission path is to be estimated. Here, “close” is expressed by the following equation (1) when the coordinate of the pilot symbol is (K, L), the symbol rate normalized Doppler frequency fd, and the symbol period normalized multipath maximum delay time ds. It means that the distance d is small.
d = {(Kk) * fd} ² + {(Ll) * ds} ² (1)

  The smaller the fd, the greater the correlation in the time (symbol) direction, and the smaller the ds, the greater the correlation in the frequency (subcarrier) direction. Selecting a pilot to be used according to equation (1) means selecting a pilot component having a large correlation with the (k, l) component in order to estimate the channel estimation value of the (k, l) component with higher accuracy. It means that.

<Calculation method of B>
The optimal weighting coefficient vector w (k, l) for M (four in this embodiment) pilots used for estimating the (k, l) component is an autocorrelation matrix Φ between the four pilot symbols to be used. , And the (k, l) component to be estimated and the cross-correlation vector θ (k, l) of the four pilots are expressed by the following equation (2). “T” indicates transposition.
w ^T (k, l) = θ ^T (k, l) Φ ⁻¹ (2)

Here, assuming that the transmission path is in a broad sense, the (k, l) component for which the transmission path estimation value is to be obtained, and the pilot (K _m , L selected in accordance with Equation (1) in <Selection Method A> _m ) (0 ≦ m ≦ 3) and a cross-correlation value θ (kK _m , lL _m ), and four pilots (K _{m ′} , L _{m ′} ) (including (K _m , L _m ) and itself) The correlation vector Φ (K _m −K _{m ′} , L _m −L _{m ′} ) with 0 ≦ m ′ ≦ 3) is expressed as in Equations (3) and (4) using the signal-to-noise power ratio sn. expressed. Further, the correlation matrix Φ between all pilots to be used is expressed as in Expression (5) using Φ (K _m −K _{m ′} , L _m −L _{m ′} ).

θ (kK _m , lL _m ) = sinc (2π * fd * (kK _m )) * sinc (2π * ds * (lL _m )) (3)
Φ (K _m -K _{m '} , L _m -L _m' ) = δ (K _m -K _{m '} , L _m -L _m' ) / sn + θ (K _m -K _{m '} , L _m -L _m' ) ... (4)
Φ = (Φ (K ₀ -K _{m '} , L ₀ -L _m' ), Φ (K ₁ -K _{m '} , L ₁ -L _m' ), Φ (K ₂ -K _{m '} , L ₂ -L _{m ′} ), Φ (K ₃ -K _{m ′} , L ₃ -L _{m ′} ))… (5)

The above is the selection method of A and the calculation method of B described in Non-Patent Document 1, but as described in the background art section, in the calculation method of B, for all (k, l) components, In order to calculate w ^T (k, l) in equation (2), the inverse matrix of Φ shown in equation (5) was calculated.

  Here, paying attention to the equations (1), (3) to (5), the values necessary for the calculation of d, θ, and Φ are used as the (k, l) component for which the transmission path estimation value is to be obtained. It depends only on the positional relationship of pilots and transmission path parameters, and does not depend on the received signal. In addition, since the positional relationship between the (k, l) component and the pilot used in the transmission path estimation is determined depending on only the transmission path parameters from Equation (1) if the pilot coordinate arrangement in the frame is determined, transmission If only the road parameters are determined, w (k, l) in equation (2) is uniquely determined.

  Since the fluctuation range of the transmission path parameter is narrowed to some extent by the communication system, it is possible to perform near-optimal transmission path estimation according to the state of the transmission path with a small number of weighting coefficient tables.

  Next, detailed operation of the receiving apparatus according to the present embodiment will be described with reference to the drawings. First, conditions assumed by this receiving apparatus will be described.

  FIG. 3 is a diagram illustrating an example of a frame structure of an OFDM signal demodulated by the receiving apparatus according to the present embodiment. In FIG. 3, a white square (□) and a black square represent one subcarrier symbol component, the horizontal direction represents a subcarrier, and the vertical direction represents a symbol. One frame is composed of 32 subcarriers and 16 symbols, □ represents a data symbol component, and the rest represents a pilot symbol component.

  The pilot symbol component is obtained by BPSK (Binary Phase-Shift Keying) modulation of a known bit sequence on both the transmission side and the reception side, and is included in one frame in the configuration example shown in FIG.

  The data symbol component is a symbol in which a bit sequence that is not known on the receiving side is modulated by 256 QAM (Quadrature Amplitude Modulation) on the transmitting side, and is included in 480 excluding 32 pilot symbols in one frame.

  Further, it is assumed that four samples of GI are added per OFDM signal symbol as a countermeasure against interference due to delayed waves.

  In the present embodiment, the weighting coefficient table held by the weighting table unit 66 has eight types (tables # 0 to # 7) each corresponding to eight transmission line states as shown in FIG. And That is, the weighting table unit 66 holds eight types of tables in which a plurality of weighting coefficients corresponding to each pilot symbol arranged in one frame are described, and the weighting coefficient included in each table is the transmission path state. It is a value according to. For example, the table # 0 is used for channel estimation when fd (symbol rate normalized Doppler frequency) and ds (symbol period normalized multipath maximum delay time) are small and sn (signal-to-noise power ratio) is large. The weighting coefficient is tabulated.

  Each table includes (k, l) components (480 components in which data symbols are arranged) in a frame and M (four in this embodiment) pilots used for channel estimation. A weighting factor for each combination is included. In other words, 480 × M records (sequence of associated information) are included in one table, and one record includes identification information (for example, coordinates (k, l) of a processing target (transmission path estimation target). )), Identification information (for example, coordinates) of four pilot symbols used for channel estimation in that component, and four weighting coefficients respectively corresponding to these four pilot symbols.

  Next, the detailed operation of the receiving apparatus will be described with reference to FIGS.

  In the receiving apparatus of the present embodiment, receiving antenna 1 receives a signal (OFDM signal having the frame configuration shown in FIG. 3) transmitted from a transmitter (not shown), and receives it as analog signal 2 as received signal S11. Let them enter. The analog unit 2 down-converts the input reception signal S11 to convert it into a baseband analog signal S21 and outputs it to the AD conversion unit 3. Here, the analog unit 2 may include one or more of LNA (Low Noise Amplifier), analog LPF (Low Pass Filter), AGC (Automatic Gain Control), and AFC (Automatic Frequency Control).

  The AD conversion unit 3 samples the input baseband analog signal S21 to convert it into a baseband digital reception signal S31 and outputs it to the time domain processing unit 4.

  The time domain processing unit 4 removes the GI from the input baseband digital reception signal S31, converts it to a GI removal time signal S41, and outputs it to the FFT unit 5. Note that the time domain processing unit 4 performs one or more of a process for performing symbol synchronization and frame synchronization before removing GI from the input baseband digital received signal S31. May be included.

  The FFT unit 5 performs 32-point FFT by serial / parallel conversion of the input GI removal time signal S41 every 32 samples. The frequency signal obtained by executing the FFT is parallel / serial converted every 32 points, and the resulting signal is output to the frequency domain processing unit 6 as the frequency signal S51.

  In the frequency domain processing unit 6 (see FIG. 2), the frequency signal S51 input from the FFT unit 5 is input to the pilot separation unit 61 and the transmission path parameter estimation unit 64.

  The pilot separation unit 61 of the frequency domain processing unit 6 separates the input frequency signal S51 into a data component (corresponding to the component indicated by □ in FIG. 3) and a pilot component, and the data component is transmitted as a received data signal S611. The pilot component is output to the equalization unit 68, and the pilot component is output to the replica multiplication unit 63 as a reception pilot signal S612.

  The replica generation unit 62 generates a replica signal S621 corresponding to the reception pilot signal S612 by performing BPSK modulation on the known sequence. Further, the replica signal S621 is output to the replica multiplier 63.

  Replica multiplier 63 multiplies reception pilot signal S612 input from pilot separator 61 by the complex conjugate of replica signal S621 input from replica generator 62 to calculate pilot transmission line gain S631. Further, pilot transmission path gain S631 is output to transmission path estimation section 67.

  The transmission path parameter estimation unit 64 generates an estimated transmission path parameter S641 indicating the state of the transmission path based on the input frequency signal S51 and outputs it to the table selection unit 65. Here, the estimated transmission path parameter S641 is, for example, a symbol rate normalized Doppler frequency (fd), a symbol period normalized multipath maximum delay time (ds), and a signal-to-noise power ratio (sn). However, any one or two of these fd, ds, and sn may be used. In this embodiment, the input signal to the transmission path parameter estimation unit 64 is the frequency signal S51. However, the present invention is not limited to this. The baseband digital reception signal S31, the GI-removed time signal S41, the frequency signal S51, Any one or two or more of received pilot signal S612, replica signal S621, and pilot transmission line gain S631 may be input to parameter estimation unit 64. The method for generating each parameter is not particularly specified.

  The table selection unit 65 is a table selection signal indicating one of eight types of weighting coefficient tables held in the weighting table unit 66 based on the estimated transmission path parameter S641 input from the transmission path parameter estimation unit 64. S651 is generated and output to the weighting table unit 66. Specifically, the table selection unit 65 compares each parameter included in the input estimated transmission path parameter S641 (here, fd, ds, and sn as described above) with a corresponding predetermined threshold value. Then, a table selection signal S651 having a value corresponding to the comparison result is generated. For example, the threshold values shown in FIG. 4 are FDth (threshold value for determining the Doppler frequency), DSth (threshold value for determining the multipath maximum delay time), SNth (signal-to-noise power ratio). Table selection signal indicating any numerical value from “0” to “7” according to the magnitude relationship between these threshold values and each parameter (fd, ds, sn) S651 is generated. The value of the table selection signal S651 is determined as follows.

Table selection signal “0” output condition Signal to noise power ratio (sn) ≧ SNth and symbol rate normalized Doppler frequency (fd) <FDth and symbol period normalized multipath maximum delay time (ds) <DSth
Table selection signal “1” output condition Signal to noise power ratio (sn) ≧ SNth and symbol rate normalized Doppler frequency (fd) ≧ FDth and symbol period normalized multipath maximum delay time (ds) <DSth
Table selection signal “2” output condition Signal to noise power ratio (sn) ≧ SNth and symbol rate normalized Doppler frequency (fd) <FDth and symbol period normalized multipath maximum delay time (ds) ≧ DSth
Table selection signal '3' output condition Signal-to-noise power ratio (sn) ≧ SNth and symbol rate normalized Doppler frequency (fd) ≧ FDth and symbol period normalized multipath maximum delay time (ds) ≧ DSth
Table selection signal “4” output condition Signal-to-noise power ratio (sn) <SNth and symbol rate normalized Doppler frequency (fd) <FDth and symbol period normalized multipath maximum delay time (ds) <DSth
Table selection signal “5” output condition Signal to noise power ratio (sn) <SNth and symbol rate normalized Doppler frequency (fd) ≧ FDth and symbol period normalized multipath maximum delay time (ds) <DSth
Table selection signal '6' output condition Signal to noise power ratio (sn) <SNth and symbol rate normalized Doppler frequency (fd) <FDth and symbol period normalized multipath maximum delay time (ds) ≧ DSth
Table selection signal “7” output condition Signal to noise power ratio (sn) <SNth and symbol rate normalized Doppler frequency (fd) ≧ FDth and symbol period normalized multipath maximum delay time (ds) ≧ DSth

  The weighting table unit 66 assigns numbers “0” to “7” to the eight types of weighting coefficient tables and manages them, and when a table selection signal S651 is input from the table selection unit 65, this signal indicates. The table corresponding to the selected number is selected, and the table value S661 (information registered in the selected table) is output to the transmission path estimation unit 67.

  The transmission path estimation unit 67, based on the input pilot transmission path gain S631 and the table value S661, transmits a transmission path estimation value for each (k, l) component (component in which data symbols are arranged) in one frame. Is calculated. Specifically, the transmission path estimation unit 67 first confirms the table value S661, and grasps the four pilot transmission path gains S631 used in calculating the transmission path estimation value of the (k, l) component to be processed. Then, multiply-add the four pilot transmission line gains and the corresponding four weighting coefficient vectors, and use the obtained calculation result to transmit the (k, l) component (the component to be processed). The estimated road value. By executing the above processing for each component (component in which data symbols are arranged) in one frame, transmission is performed for each of 480 components (coordinates) in which data symbols are arranged in one frame. A road estimation value is calculated. The calculated 480 transmission channel estimation values are output to the transmission channel equalization unit 68 as transmission channel estimation values S671.

  The transmission path equalization unit 68 converts each data signal S611 input from the pilot separation unit 61 into a transmission path estimation value S671 corresponding to the coordinates (k, l) (the 512 pieces of the output from the transmission path estimation unit 67). Is divided by one transmission path estimation value corresponding to the data signal to be processed) to generate an equalized data signal S681.

  Note that the transmission path equalization unit 68 of the present embodiment does not assume MIMO (Multi-Input Multi-Output), but performs transmission for the number of transmission / reception antennas that can be separated by MIMO and the number of transmission antennas × the number of reception antennas. A channel estimation value may be input and transmission path equalization corresponding to MIMO may be performed.

  The demapping unit 69 applies a modulation scheme (256QAM in this embodiment) applied on the signal transmission side to the equalized data signal S681 output from the transmission path equalization unit 68. Corresponding demodulation processing is performed, and the soft decision bit sequence S61 is output to the error correction decoding unit 7.

  The error correction decoding unit 7 performs error correction processing on the input soft decision bit sequence S61 and outputs a decoded bit sequence S71. The error correction decoding unit 7 performs error correction by turbo decoding, for example. Of course, other decoding methods may be applied.

  As described above, the receiving apparatus according to the present embodiment associates the weighting coefficient table used in the transmission path estimation with the possible values of the parameters (for example, fd, ds, and sn) described above. When the transmission path is estimated, an optimum table is identified based on the state of the transmission path, and the transmission path is estimated using the table. Specifically, a table is specified by determining the threshold value of each parameter, and transmission path estimation is performed using data included in the specified table. As a result, when the fluctuation of the transmission path is large, transmission path estimation suitable for each case can be realized by only the product-sum operation, and the calculation amount can be reduced.

  In this embodiment, in order to simplify the description, a different weighting coefficient is associated with each (k, l) component in one frame so that 480 × 4 records are included in one table. Although an example in the case of the above has been described, it is possible to reduce the amount of data to be stored in a table by doing as follows. That is, when pilot symbols are periodically arranged (for example, the arrangement shown in FIG. 3), the (k, l) components in which data symbols are arranged include four neighboring pilots. A plurality of symbols having the same positional relationship with symbols (pilot symbols used in channel estimation) are included. Therefore, the same weighting coefficient can be used for channel estimation of components having the same positional relationship with four neighboring pilot symbols. Therefore, by sharing the weighting coefficient corresponding to each component having the same positional relationship with the four neighboring pilot symbols, the amount of information stored in a table can be reduced.

Embodiment 2. FIG.
Next, the receiving apparatus according to the second embodiment will be described. In the first embodiment described above, the receiving apparatus configured to estimate the transmission path parameter and select the weighting coefficient table based on the estimation result has been described. However, in the present embodiment, estimation of the transmission path parameter is omitted. A receiving apparatus that performs transmission path estimation using an optimal weighting coefficient table will be described.

  FIG. 5 is a diagram illustrating a configuration example of a frequency domain processing unit included in the receiving apparatus of the second embodiment. The frequency domain processing unit 6a according to the present embodiment includes a transmission path parameter estimation unit 64, a table selection unit 65, and a weighting table unit 66 of the frequency domain processing unit 6 (see FIG. 2) described in the first embodiment. 66a, pilot transmission path estimation unit 70, estimation error calculation unit 71, and estimation error comparison unit 72. In addition, pilot transmission path estimation unit 70, estimation error calculation unit 71, and estimation error comparison unit 72 constitute table specifying means. The same components and signals as those of the frequency domain processing unit 6 shown in FIG. 2 are denoted by the same reference numerals as those in FIG. As in the first embodiment, an example in which the frame configuration shown in FIG. 3 and the eight types of weighting coefficient tables shown in FIG. 4 are used will be described.

  In the receiving apparatus of the present embodiment, replica multiplication section 63 outputs generated pilot transmission line gain S631 to transmission path estimation section 67, pilot transmission path estimation section 70, and estimation error calculation section 71.

  The weighting table unit 66a (corresponding to the table holding unit) outputs a weighting coefficient table corresponding to the input table selection signal S721 to the transmission path estimation unit 67, similarly to the weighting table unit 66 of the first embodiment. However, in the present embodiment, each table held in the weighting table unit 66a includes records for all 520 (k, l) components including components in which pilot symbols are arranged (each component has Corresponding 520 records). The table selection signal S721 is generated by the estimation error comparison unit 72. In addition, the weighting table unit 66a outputs eight types of table values S662 to the pilot transmission path estimation unit 70 in ascending order of table numbers for 32 pilot components included in one frame.

  The pilot transmission line estimation unit 70 multiplies the pilot component table value S662 (weighting coefficient corresponding to the transmission line state) input from the weighting table unit 66a and the pilot transmission line gain S631 input from the replica multiplication unit 63. By calculating the sum, transmission path estimation values of 32 pilot components are calculated. The pilot transmission path estimation unit 70 performs this process for all eight types of tables, and sequentially outputs transmission path estimation values corresponding to the tables to the estimation error calculation section 71 as transmission path estimation values S701. That is, the pilot transmission line estimation unit 70 is configured to provide one component based on the estimation result (pilot transmission line gain S631) using the four pilot symbols adjacent to the component that is the target of transmission line estimation and the table value S662. Eight transmission path estimation values are calculated per one.

  The estimation error calculation unit 71 transmits each pilot transmission channel estimation value S701 input from the pilot transmission channel estimation unit 70 (transmissions calculated using pilot symbols adjacent to the target component of transmission channel estimation and eight types of weighting coefficient tables). Path estimated value) and the error power (power difference) between pilot transmission path gain S631 (transmission path estimated value obtained directly from pilot symbols arranged in the target component of transmission path estimation) input from replica multiplier 63 ) And the error power for 32 pilot symbols is added to obtain the total error power. The estimation error calculation unit 71 performs the calculation of the total error power for each of the eight pilot channel estimation values S701 sequentially output from the pilot channel estimation unit 70, and calculates the total error power S711 corresponding to each table as the table number. Are output to the estimation error comparison unit 72 in the order in accordance.

  Here, among the pilot transmission channel estimation values S701 input from the pilot transmission channel estimation unit 70, those calculated using the table values corresponding to the transmission channel state at that time are calculated using other tables. Compared to the above, it should be a value closer to the pilot transmission line gain S631, which is a transmission line estimation value obtained directly from the pilot symbols arranged in the transmission path estimation target component.

  Therefore, the estimated error comparison unit 72 confirms the eight total error powers S711 input in the order of the table numbers, generates a table selection signal S721 indicating the table number with the smallest total error power, and generates the weighting table unit 66a. Output to.

  By doing as described above, the estimation of the transmission path parameter required in the first embodiment is omitted, and the table with the smallest error from the eight tables (corresponding to the transmission path state at that time) It is possible to estimate the transmission path of the data component by selecting the optimum table. Even when such a configuration is applied, the same effect as in the first embodiment can be obtained.

Embodiment 3 FIG.
FIG. 6 is a diagram illustrating an example in which the receiving device described in the first embodiment and the receiving device described in the second embodiment are used in mobile communication using a leaky coaxial cable (LCX: Leaky CoaXial cable). is there.

  In the communication system shown in FIG. 6, the base station 8 and the repeater 9 are connected by using either an optical fiber cable or a coaxial cable, and the base station 8 is either an analog modulation signal or a digital modulation signal. Signal S81 is transmitted, and this signal S81 is input to the repeater 9.

  The repeater 9 amplifies the received signal S81 and outputs an analog signal S91 to the leaky coaxial cable 10. The repeater 9 may include one or more of a digital-analog conversion function and a signal amplification function.

  The leaky coaxial cable 10 transmits an analog signal S91 input from one end and outputs it as a radio signal S101 from a slit provided in the cable.

  The mobile station 11 moving beside the leaky coaxial cable 10 receives the radio signal S101 output from the leaky coaxial cable 10 with an antenna, and uses the receiving apparatus described in the first or second embodiment to transmit the signal. Demodulate.

  By configuring the communication system in this way, it is possible to apply the receiving apparatus described in Embodiments 1 and 2 to mobile communication using a leaky coaxial cable.

  Moreover, the communication system shown in FIG. 7 can be considered as a modification of the communication system using the leaky coaxial cable. In the communication system shown in FIG. 7, different radio signals S101 and S121 output from two or more leaky coaxial cables 10 and 12 are simultaneously received by two or more antennas installed in the mobile station 11. Like to do. As described above, even in mobile communication using a leaky coaxial cable, it is possible to demodulate a spatially multiplexed signal.

  As described above, the receiving apparatus according to the present invention is useful when receiving a multicarrier signal, and is particularly suitable for a receiving apparatus that performs transmission path estimation with a small amount of computation.

DESCRIPTION OF SYMBOLS 1 Antenna 2 Analog part 3 AD conversion part 4 Time domain process part 5 FFT part 6, 6a Frequency domain process part 7 Error correction decoding part 8 Base station 9 Repeater 10, 12 Leaky coaxial cable 11 Mobile station 61 Pilot separation part 62 Replica Generation unit 63 Replica multiplication unit 64 Transmission channel parameter estimation unit 65 Table selection unit 66, 66a Weighting table unit 67 Transmission channel estimation unit 68 Transmission channel equalization unit 69 Demapping unit 70 Pilot transmission channel estimation unit 71 Estimation error calculation unit 72 Estimation Error comparison unit

Claims (3)

A multicarrier signal receiving apparatus in which pilot signals are periodically arranged for each frame of a predetermined number of symbols,
Replica generating means for generating a replica of the pilot signal;
Transmission line gain calculating means for multiplying each received pilot signal in the frame by the complex conjugate of the replica to calculate a transmission line gain at each pilot signal position indicated by time and frequency;
For each signal position, there is a weighting coefficient for weighting each transmission path estimated value indicated by the information of the pilot signal position used in calculating the transmission path estimated value in a specific transmission path state. Table holding means for holding a plurality of registered tables;
Based on the transmission path gains at the pilot signal positions other than the estimation target position calculated by the transmission path gain calculation means and the table held by the table holding means, the transmission path estimation values at the respective pilot signal positions. A plurality of calculated channel estimation values are compared with the channel gain at the estimation target position calculated by the channel gain calculating unit, and the table holding unit is based on the comparison result. Table specifying means for specifying one of the tables held in
Transmission path estimation for calculating a transmission path estimation value at each position where no pilot signal is arranged based on the transmission path gain calculated by the transmission path gain calculation means and the table specified by the table specification means Means,
A receiving apparatus comprising: The transmission path estimation means includes a signal position for calculating a transmission path estimation value, and a transmission path estimation value of a pilot signal position used in calculation of the transmission path estimation value registered in the table specified by the table specifying means. Based on the information, a part of the transmission line gain calculated by the transmission line gain calculating means is selected, and the selected transmission line gain and the weighting coefficient registered in the table are selected. based on the bets, the receiving apparatus according to claim 1, characterized in that to calculate the channel estimation value in the signal position. The transmission path estimation means calculates a transmission path estimated value by performing a product-sum operation on the selected transmission path gain and the weighting coefficient corresponding to each of the selected transmission path gains. 2. The receiving device according to 2 .

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