JP2003174427A - Receiver for synthesizing ofdm signal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a receiver for synthesizing an OFDM signal capable of satisfactorily reproducing a signal with a desired wave even under a situation that frequency selectivity distortion occurs due to the mixing of multi-pulse components. <P>SOLUTION: An OFDM signal is received by each of a plurality of antenna branches 0-(L-1) constituting a reception antenna, and a scattered pilot signal included in the received OFDM signal is extracted (110), and signal synthesis is performed based on the extracted pilot signal (130), and an error from a prescribed reference value is extracted (150, 160), and a synthetic weighting factor for the scattered pilot signal is generated based on the extracted error (140), and an interpolated synthetic weighting factor for performing signal synthesis for each symbol number and carrier number for specifying each signal is generated (170), and signal synthesis concerning a branch direction is performed based on the interpolated synthetic weighting factor and the OFDM signal (120). <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to OFDM (Orthog
The present invention relates to a receiver for synthesizing an OFDM signal of digital broadcasting or digital transmission that adopts the onal Frequency Division Multiplexing method, and in particular, it relates to fading and interference waves generated when receiving radio waves such as digital broadcasting and wireless LAN. Applying adaptive array antenna technology or diversity combining technology to remove O
The present invention relates to a receiver for FDM signal synthesis.

[0002]

2. Description of the Related Art Conventionally, adaptive array antenna technology has been used by John Litova and Thai Taskoc-Yon.
Rho, "Digital Beamforming in the Wireless Communication Field", Artec House Publishers,
1996 ("Digital Beam-forming in Wireless Commu
nication ”, John Litva, Titus Kwok-Yeung Lo, Artec
h House Publishers, 1996), Simon Haikin (Si
mon Hykin), translated by Hiroshi Suzuki, "Adaptive Filter Theory", Science and Technology Publishing, 2001 and other books. In the adaptive array antenna technology, each antenna is weighted according to the reception status and the signals received by each antenna are combined (hereinafter referred to as beamforming).
Is done.

These books include single carrier PSK.
(Phase Shift Keying) and multi-valued QAM (Quadrature
In digital transmission methods such as Amplitude Modulation), LMS (Least Mean Square) algorithm and R
An adaptive array antenna and a transmission line equalizer to which an LS (Recursive least squares) algorithm is applied are described in detail.

On the other hand, as an adaptive array antenna technology for receiving an OFDM signal, Satoshi Hori, Nobuyoshi Kikuma, Naoki Inagaki, "MMSE Adaptive Array Using Guard Interval in OFDM", Technical Report, AP20
01-50 (2001-07) (hereinafter referred to as Reference 1), Toru Nishikawa, Yoshitaka Hara, Shinsuke Hara, "A Study on Adaptive Array for OFDM in Mobile Communication", IEICE Technical Report,
RCS-2000-232 (2001-03) (hereinafter,
Reference 2 ), Takeo Fujii, Masao Nakagawa, "OFDM Indoor Multi-Station Simultaneous Frequency Simultaneous Transmission System Using Smart Antenna", IEICE Technical Report, RCS2000-83 (200).
0-07) (hereinafter referred to as Document 3).

[0005]

However, in the technique disclosed in the above-mentioned document 1, when frequency selective distortion occurs due to the multipath component of the desired wave being mixed in the received wave, each sub-signal forming the OFDM signal is Since the reception status of the carrier is different and the optimum weighting coefficient for beamforming for each subcarrier is different, suitable beamforming cannot be performed for all subcarriers,
There is a problem that the desired wave signal cannot be reproduced well.
Further, the technique disclosed in Document 2 above monitors virtual subcarriers that are not actually used for signal transmission and determines a composite weighting coefficient (or a weighting coefficient for beamforming) of each array antenna. Therefore, there is a problem similar to that of the technique disclosed in Document 1 above.

[0006] On the other hand, the technique disclosed in the above-mentioned document 3 uses the fast Fourier transform (Fa) of the OFDM signal for each array antenna.
st Fourier Transform), and the RLS algorithm is applied to each subcarrier after the fast Fourier transform to synthesize the subcarriers. By applying such an algorithm, the optimum beam pattern is formed for each subcarrier, and therefore, the effect of frequency-selective distortion due to multipath in the propagation path becomes strong. A training (pilot) signal (hereinafter referred to as a pilot signal) in the technique disclosed in Document 3 is based on pilot signals that are uniformly arranged in the carrier direction and the symbol direction at regular intervals. Then, the combined weighting coefficient of each array antenna is calculated for each subcarrier.

However, ISDB-T (Integrated Serv), which is the current broadcasting system for terrestrial digital television broadcasting, is used.
ices Digital Broadcasting-Terrestrial) and DVB
The -T (Digital Video Broadcasting-Terrestrial) system adopts the OFDM system, and a signal called a Scattered Pilot (hereinafter referred to as SP) signal is inserted. This SP signal has an arrangement in which pilot carriers are dispersed in both the carrier direction and the symbol direction, as shown in FIG.
There is a problem in that the technology disclosed in Document 3 cannot be applied as it is.

The present invention has been made to solve such a problem, and its purpose is to provide an O signal based on an SP signal.
By making it possible to optimally combine the signals from the array antenna for each subcarrier of the FDM signal, it is possible to excellently reproduce the signal of the desired wave even under the condition that frequency selective distortion occurs due to mixing of multipath components. OFDM
An object is to provide a signal combining receiver.

[0009]

In view of the above points, in the invention according to claim 1, each of a plurality of antenna branches forming a receiving antenna receives an OFDM signal,
Reception for synthesizing a signal having the same symbol number and carrier number, which is a subcarrier number, for identifying signals that are to be compared with each other among the antenna branches among signals that form an FDM signal In the device,
Means for performing a fast Fourier transform process on the OFDM signal received for each antenna branch to generate an OFDM spectrum; and from the OFDM spectrum for each antenna branch, which of the symbol number and the carrier number Pilot carrier extraction means for extracting SP signals which are the same and are scattered pilot signals, and each SP signal specified by the same symbol number and the same carrier number,
Pilot carrier combining means for applying a combining weighting coefficient in accordance with a carrier number for identifying each SP signal and a branch number which is an antenna branch number, and adding for each subcarrier to generate a combined signal, Pilot signal generating means for generating a reference combined value, which is predetermined information regarding a value indicated by the SP signal specified by a symbol number for specifying the combined signal and a carrier number for specifying the combined signal. And an estimation error that is a value obtained by subtracting, from the reference combined value, a value indicated by the combined signal having the same symbol number and carrier number for specifying the reference combined value and the combined signal. Means for generating
Depending on the estimation error and the SP carrier number that is the subcarrier to which the SP signal is assigned, SP
Coefficient updating means for generating a composite weighting coefficient for each antenna branch for each carrier, and performing a predetermined interpolation process regarding the symbol number and the carrier number based on each composite weighting coefficient generated by the coefficient updating means, A combined weighting coefficient vector specified by the same symbol number and the same branch number,
Interpolation means for generating a composite weighting coefficient vector whose elements are composite weighting coefficients according to carrier numbers,
A value obtained by multiplying each signal forming the OFDM signal by a composite weighting coefficient specified by a symbol number and a carrier number equal to a symbol number and a carrier number for identifying the signal forming the OFDM signal, Carrier combining means for generating a combined signal by adding in the carrier number direction, and the predetermined combining weighting coefficient applied by the pilot carrier combining means is a combining weighting coefficient generated by the coefficient updating means. have.

With this configuration, it is possible to optimally combine the signals from the array antenna for each subcarrier of the OFDM signal based on the scattered pilot signals in which the pilot signals are not evenly inserted, thereby enabling multipath It is possible to realize a receiving device for OFDM signal synthesis which can favorably reproduce a signal of a desired wave even in a situation where frequency selective distortion due to mixing of components occurs.

According to the second aspect of the invention, each of the plurality of antenna branches forming the receiving antenna is OFDM.
A signal having the same symbol number and the same carrier number that is a subcarrier number for receiving signals and identifying signals that are to be compared with each other among the antenna branches among the signals that form the OFDM signal. A means for generating an OFDM spectrum by performing a fast Fourier transform process on the OFDM signal received for each of the antenna branches,
Pilot carrier extraction means for extracting an SP signal that is a scattered pilot signal, in which both the symbol number and the carrier number are the same, from the OFDM spectrum for each antenna branch, and the same symbol number and the same carrier number. Each SP signal specified by is multiplied by a combining weighting coefficient according to a carrier number for identifying each SP signal and a branch number which is an antenna branch number, and added to each subcarrier to generate a combined signal. Pilot carrier synthesizing means for controlling, a reference synthetic value which is predetermined information regarding a value indicated by the SP signal specified by a symbol number for specifying the synthetic signal and a carrier number for specifying the synthetic signal. To generate the pilot signal And an estimation error that is a value obtained by subtracting, from the reference combined value, a value indicated by the combined signal having the same symbol number and carrier number for specifying the reference combined value and the combined signal. For generating a combined weighting coefficient for each antenna branch for each SP carrier according to the means for generating, the estimation error, and the SP carrier number that is the subcarrier to which the SP signal is assigned. Coefficient updating means and the S generated by the coefficient updating means.
By performing a predetermined interpolation process on the composite weighting coefficient for each antenna branch for each P carrier, a composite weighting coefficient for a data carrier that is a subcarrier other than the SP carrier is generated, and for each antenna branch Interpolation means for converting the composite weighting coefficient for each carrier and performing inverse Fourier transform processing to generate a filter coefficient vector, and the OFD having the same symbol number for each antenna branch.
The pilot signal is provided with a time domain synthesizing unit for generating a synthesized signal by performing a predetermined convolution integration process with a value indicated by the signal of each carrier forming the M signal and the corresponding filter coefficient vector, and adding them. The predetermined combining weighting coefficient applied by the carrier combining means is a combination weighting coefficient generated by the coefficient updating means.

With this configuration, it is possible to optimally combine the signals from the array antenna for each subcarrier of the OFDM signal based on the scattered pilot signals in which the pilot signals are not evenly inserted, and thus, the multipath It is possible to realize a receiving device for OFDM signal synthesis which can favorably reproduce a signal of a desired wave even in a situation where frequency selective distortion due to mixing of components occurs.

Further, in the invention according to claim 3, the coefficient updating means is configured to generate the combined weighting coefficient based on an LMS (Least Mean Square) algorithm or an RLS algorithm (Recursive Least Squares). . With this configuration, it is possible to optimally combine the signals from the array antenna for each subcarrier of the OFDM signal based on the scattered pilot signal in which the pilot signal is not uniformly inserted,
OFD that can reproduce the signal of the desired wave satisfactorily even under the condition that frequency selective distortion occurs due to mixing of multipath components
A receiver for M signal synthesis can be realized.

According to a fourth aspect of the present invention, the filter coefficient vector is a transversal filter coefficient vector, the time domain synthesis means is composed of a transversal filter and an addition means, and the transversal filter is For each antenna branch, a predetermined convolution integration process is performed on the transversal filter coefficient vector and the value indicated by the OFDM signal, and the adding means integrates the values obtained by the convolution integration process to obtain a combined signal. Have a configuration.

With this configuration, it is possible to optimally combine the signals from the array antenna for each subcarrier of the OFDM signal based on the scattered pilot signals in which the pilot signals are not evenly inserted, so that the multipath It is possible to realize a receiving device for OFDM signal synthesis which can favorably reproduce a signal of a desired wave even in a situation where frequency selective distortion due to mixing of components occurs.

Further, in the invention according to claim 5, the interpolating means is composed of inter-symbol interpolating means and inverse Fourier transforming means, and the inter-symbol interpolating means, with respect to the combined weighting coefficient, has a symbol number. With respect to the transversal filter coefficient vector by performing an inverse Fourier transform process on the combined weighting coefficient vector subjected to the interpolation process with respect to the symbol number. Has a configuration that is a means for generating.

With this configuration, it is possible to optimally combine the signals from the array antenna for each subcarrier of the OFDM signal based on the scattered pilot signals in which the pilot signals are not evenly inserted, thereby enabling multipath It is possible to realize a receiving device for OFDM signal synthesis which can favorably reproduce a signal of a desired wave even in a situation where frequency selective distortion due to mixing of components occurs.

According to a sixth aspect of the present invention, the interpolating means is composed of inter-symbol interpolating means, inter-carrier interpolating means and inverse Fourier transforming means, and the inter-symbol interpolating means is composed and weighted. Means for performing a predetermined interpolation process on the coefficient with respect to the symbol number, wherein the inter-carrier interpolation means performs a predetermined interpolation process on the carrier number with respect to the combined weighting coefficient vector obtained by the interpolation process. The inverse Fourier transform means performs the inverse Fourier transform process on the combined weighting coefficient vector that has been subjected to the interpolation process with respect to a symbol number and has been subjected to the interpolation process with respect to a carrier number, and It has a configuration that is a means for generating a transversal filter coefficient vector.

With this configuration, it is possible to optimally combine the signals from the array antenna for each subcarrier of the OFDM signal based on the scattered pilot signals in which the pilot signals are not evenly inserted, so that the multipath It is possible to realize a receiving device for OFDM signal synthesis which can favorably reproduce a signal of a desired wave even in a situation where frequency selective distortion due to mixing of components occurs.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION An OFDM signal combining receiver of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram showing a schematic configuration of an OFDM signal combining receiving apparatus 100 according to the first embodiment of the present invention. The OFDM signal synthesizing receiver 100 includes antenna branches 0 to (L-1) and a fast Fourier transform (hereinafter, FF).
It is called T (Fast Fourier Transform). ) Means 101
(0) to 101 (L-1), pilot carrier extracting means 110, carrier combining means 120, pilot carrier combining means 130, coefficient updating means 140, difference calculating means 150, pilot signal generating means 160, and interpolation means 170. Composed.

Before entering the description of each constituent means, terms, symbols, definitions, etc. will be described. ISDB-T (Integrat) which is a broadcasting system of terrestrial digital television broadcasting
ed Services Digital Broadcasting-Terrestrial) and DVB-T (Digital Video Broadcasting-Terre)
A reference signal called a Scattered Pilot (hereinafter referred to as SP) signal is inserted in a signal transmitted in the strial system. Figure 8
Shows the arrangement of SP signals in the carrier-symbol space. In FIG. 8, SP signals are represented by black circles, and data signals that are other signals are represented by white circles.

In the following, the number L of antenna branches (hereinafter simply referred to as "branches") forming a receiving antenna is referred to as the number of branches, and the branch number, which is the number assigned to an arbitrary branch, is l (0≤ 1 ≦ L-1). In addition, K is the total number of subcarriers forming the OFDM signal.
(K is an odd number), and a number assigned to an arbitrary subcarrier (hereinafter, simply referred to as a carrier number) is represented by k (0 ≦).
k≤K-1). Furthermore, a number (generally corresponding to time. Below, attached to an arbitrary symbol forming the OFDM signal.
This is called a symbol number. ) Is i.

In the signal arrangement shown in FIG. 8, when the symbol number is i, the carrier number of the carrier that is the SP signal (hereinafter referred to as SP carrier) is k _p.
Then (hereinafter, the carrier number of the SP carrier is also referred to as the SP carrier number), the SP carrier number k _p
Is defined by the following equation (1).

[Equation 1] Here, (immod4) represents the remainder when i is divided by 4, and p is a non-negative integer.

Also, any symbol number i and carrier number
OFDM signal vector specified by signal ku _k(i)
Defined by the equation (2) of
OFDM signal vector specified by lunch number lv
_l(i) is defined by the following equation (3).

[Equation 2] Here, u _{l, k} (i) is a signal specified by the branch number l, the carrier number k, and the symbol number i in the frequency spectrum of the OFDM signal (hereinafter referred to as the OFDM spectrum), and T is the transpose. Represents a vector.

Further, a composite signal y of the OFDM spectrum is obtained.
_k (i) is defined by the following equation (4).

[Equation 3] Here, wb _k (i) is a composite weighting coefficient vector specified by the carrier number k and the branch number 1, which is defined by the following equation (5), and H represents a complex conjugate transposed vector.

[Equation 4] Here, w _{l, k} (i) is a weighting coefficient specified by the branch number 1, the spectrum number k, and the symbol number i.

Next, a method of updating the combined weighting coefficient vector wb _k (i) represented by the above equation (5) by applying the LMS algorithm will be described. S specified by carrier number k _p at time i, that is, symbol number i
The difference between the total value d _kp (i) of the P signal in the branch direction and the composite signal y _kp (i) of the SP signal specified by the symbol number i and the carrier number k _p (hereinafter referred to as posterior estimation error). e _kp (i) is represented by the following equation (6).

[Equation 5]

For the same SP carrier number, the SP signal is repeated in a 4-symbol cycle, so the symbol number of the next SP signal updated based on the symbol number i is i + 4. Then, the updated value wb _kp (i +) of the combined weighting coefficient vector specified by the carrier number k _p
4) is defined by the following equation (7).

[Equation 6] Here, μ is a parameter that defines the amount of change before and after updating, which is called a step size parameter, and * represents a complex conjugate.

The combined weighting coefficient vector wb _k (i) used for combining the data signal which is a signal in the symbol-carrier space other than the SP signal is the symbol number i and the SP carrier number k calculated in this way. Composite weighting coefficient vectors wb _kp (i) and wb specified by _p and
It shall be generated by interpolation based on _kp (i + 4). The interpolation method will be described later.

Hereinafter, the receiver 100 for synthesizing an OFDM signal will be described.
Each of the constituent means will be described. FFT means 101
(0) performs a known fast Fourier transform process (hereinafter referred to as FFT process) on the OFDM signal received at the branch (shown as an antenna in FIG. 1) 0, and FF
The OFDM signal vector v _l (i) extracted from the frequency spectrum (hereinafter referred to as the OFDM spectrum) of the OFDM signal obtained by the T processing (see the above equation (3)) is the time when the OFDM signal is received. It is a means for outputting the information of the symbol number i, the branch number 1 and other necessary information to the pilot carrier extracting means 110 and the carrier synthesizing means 120.

Hereinafter, unless otherwise specified, the branch number l
OFD with arguments such as subscripts and symbol number i
When it is stated that a signal such as an M signal vector or information is input / output, the subscripts, arguments, etc. necessary for identifying it are input / output according to the signal etc., and the description is omitted. To do. FFT means 101 (1) -1
01 (L-1) performs the same processing as the processing performed by the FFT means 101 (0) on the OFDM signals received in the branches 1 to (L-1).

The pilot carrier extraction means 110 is
Output from FT means 101 (0) -101 (L-1)
Each OFDM signal vectorv _lWith (i) as input,
The SP signal when the rule number is i is shown in the above equation (1).
SP carrier number k_pAs the signal of the carrier specified by
And input each OFDM signal vectorv _lremoved from (i)
SP signal u of each extracted and extracted branch_{l, k}(i)
The OFDM signal vector is arranged as shown in the above equation (2).
Cuttleu _k(i) is generated and each OFDM signal vectoru
_k(i) shows pilot carrier combining means 130 and display
It is a means for outputting to the unit 140.

The carrier synthesizing means 120 is the FFT means 1
Each OFD output from 01 (0) to 101 (L-1)
The M signal vector v _l (i) and the composite weighting coefficient vector wb _k (i) output from the interpolation means 170 described later are input, and the above equations (2), (4), and (5) are used. combined signal y _k (i) is formed on the basis of a means for outputting the combined signal y _k (i) to the outside.

Hereinafter, in order to generate the combined weighting coefficient vector wb _k (i) used in the carrier combining means 120, the pilot carrier combining means 130 and the coefficient updating means 1
40, difference calculation means 150, pilot signal generation means 1
The processing performed by 60 and the interpolation means 170 will be described.

The pilot carrier synthesizing means 130 outputs each OF output from the pilot carrier extracting means 110.
DM signal vector u _k (i) and coefficient updating means 14 described later.
Combined weighting coefficient vector wb _kp (i) output from 0
_Are input, and the combined signal y _{kp is calculated} based on the above equation (4).
(i) is generated and output to the difference calculation means 150,
It is a means for outputting the inputted combined weighting coefficient vector wb _kp (i) to the interpolating means 170 and outputting the information of the symbol number i and the information of the carrier number k _p to the pilot signal generating means 160.

The pilot signal generating means 160 has an O
A predetermined value (hereinafter referred to as a reference combined value) d _k (i) corresponding to the value of the SP signal inserted in the FDM signal is stored in association with the symbol number i and the SP carrier number k _p , and the pilot is stored. The information of the symbol number i and the information of the SP carrier number k _p output from the carrier synthesizing unit 130 are input, and the reference synthetic value specified by the symbol number i and the SP carrier number k _p based on the input information. d _kp (i) is a difference calculation means 150 described later.
Is a means for outputting to.

The difference calculating means 150 receives the combined signal y _kp (i) output from the pilot carrier combining means 130 and the reference combined value d _kp (i) output from the pilot signal generating means 160 as input, and This is a means for calculating the posterior estimation error e _kp (i) shown in Expression (6) and outputting it to the coefficient updating means 140 described later.

The coefficient updating means 140 is a pilot carrier.
A. OFDM signal vector output from the extraction means 110
u _kp(i) and the posterior output from the difference calculation means 150
Estimation error e_kpWith (i) as input, based on the above equation (7)
Combined weighting coefficient vectorwb _kpUpdate (i),
Combined weighting coefficient vector obtained by updatingwb
_kpOutput (i + 4) to pilot carrier synthesizing means 130
It is a means to do. Here, the coefficient updating means 140
If the update process with symbol number i is completed,
Combined weighting coefficient vector obtained by processingwb
_kpIt is okay to store (i + 4) for the next processing.
Yes. It should be noted that the combination weighting factor used in the update process performed first
Number vectorwb _kpAs the value of (0), record a predetermined value.
It may be stored in advance or generated by another method.

Interpolation means 170 is a combination weighting coefficient vector output from pilot carrier combination means 130.
Using wb _kp (i) and wb _kp (i + 4) as inputs, a carrier weighting coefficient vector wb _k (i) used by the carrier synthesizing means 120 to form the synthesized signal y _k (i) is generated by interpolation, and carrier synthesizing is performed. It is means for outputting to the means 120.

FIG. 2 shows an OFDM signal synthesizing receiver 100.
By using the OFDM signal synthesizing receiver 200 having the configuration shown in FIG.
7 and inter-carrier interpolation means 278, the interpolation processing performed by the interpolation means 170 can be performed separately in the symbol axis direction and the carrier axis direction. This will be described below.

First, an interpolation method in the symbol axis direction will be described. The latest value holding method and the linear interpolation method will be described as specific examples of the interpolation method in the symbol axis direction. The latest value holding method here is the following formula (8).
As shown in, the value of the composite weighting coefficient vector wb _kp (i + 4) shown in the above formula (7), synthesized weighting coefficient vector _{wb kp (i + 1),} wb kp (i + 2), is substituted into wb _kp (i + 3) It is a thing. Needless to say, the synthetic weighting coefficient vector wb _kp (i + 4) shown in the above equation (7) is
It is obtained by the updating process in the symbol axis direction. The symbol numbers (i + 1), (i + 2), and
And (i + 3) are points between the symbol number i before updating and the symbol number i + 4 after updating.

[Equation 7]

Next, in the linear interpolation method, Δ wb _kp (i) is first generated according to the following equation (9), and the symbol number i
And the weighting coefficient vectors wb _kp (i + 1) and wb _kp (i +) for the SP signals having the symbol numbers between i + 4 and i + 4.
2) and the value of wb _kp (i + 3) is calculated according to the equations (10) to (12).

[Equation 8]

By this interpolation in the symbol axis direction, the SP signal being inserted in the carrier axis direction in the 12-carrier cycle at the time of reception is equivalent to the SP signal being inserted in the 3-carrier cycle. That is, the supplemented SP carrier number is represented by the following equation (13) instead of the above equation (1).

[Equation 9] Here, p is a non-negative integer like the above-mentioned formula (1).

Intersymbol interpolating means 277 is a pilot
Combined weighting coefficient output from carrier combining means 130
Number vectorwb _kp(i) andwb _kpInput (i + 4),
Composite weight of symbol numbers between symbol numbers i and i + 4
Find coefficient vectorwb _kp(i + 1),wb _kp(i + 2),w
b _kpThe value of (i + 3) is calculated by the above formula (8) or the above formula.
It may be generated as the values shown in (9) to (13).
Composite weighting coefficient vector obtained by interpolationwb
_kp(i + 1),wb _kp(i + 2),wb _kp(i + 3) information is
It is output to the inter-carrier interpolating means 278. In addition, the symbol
For the interpolation method in the vertical axis, a method other than the above
But good.

Next, as specific examples of the interpolation method in the carrier axis direction, three methods of the linear interpolation method, the FFT interpolation method, and the convolutional interpolation method will be described. First, the linear interpolation method will be described. By the interpolation in the symbol axis direction, the SP signal is inserted in the carrier axis direction in three carrier cycles. The linear interpolation method first generates δ wb _kp (i) according to the following equation (14), and combines weighting coefficient vector wb _{kp +} for SP signals with carrier numbers between carrier numbers k _p and k _p +3. _{The value of 1} (i), wb _{kp + 2} (i) is expressed by the formula (1
It is calculated according to 4) to (16).

[Equation 10]

By this interpolation in the carrier axial direction, all S
The composite weighting coefficient vector wb _k (i) for the P signal is determined. However, since the linear interpolation method is a first-order approximation method and the accuracy of the approximation may not be good, the following FFT interpolation method that replaces the linear interpolation method will be described below.

The composite weighting coefficient vector wb _k (i) was composed of L elements in the branch axis direction, as shown in the above equation (5). Here, defined by the carrier shaft direction of the resultant weighting coefficient vector wc _l: (i) the following equation (17).

[Equation 11]

[0047] Here, among the components of the composite weighting coefficient of the carrier shaft direction vector wc _l (i), a 0 to the element identified by the carrier number other than SP carrier number shown in the above formula (13) pack. That is, using W _{l, k} (i) shown in the following equation (18), the following equation (19)
A coefficient vector Wc _l (i) having the structure shown in FIG.
Note that this is called zero interpolation.

[Equation 12]

Next, an inverse fast Fourier transform (hereinafter referred to as IFFT (Inverse Fast Fouri) is applied to the coefficient vector Wc _l (i).
er Transform). ) Perform processing. At that time, IFF
The number of points to be T-processed is N = 2 ⁿ . Where ν
Is a natural number, and the condition of N> K is satisfied.
The impulse number (integer), which is the number given to an arbitrary impulse obtained after the IFFT processing, is n. here,
The range of n is set to the range shown in the following formula (20).

[Equation 13]

Where the coefficient vectorWc _l(i) N point
Coefficient vectorWc
_lAt the left end of (i) is a zero vector consisting of (NK-1) / 2 zeros.
Insert cutler, coefficient vectorWc _lAt the right end of (i), {(N
-K-1) / 2} Insert zero vector consisting of one zero
Then, the coefficient vector shown in the following equation (21) is generated.

[Equation 14] Here, 0 is a 0 vector defined by the following equation (22).

[Equation 15]

As shown in the above equation (21), 0 at the ends of the coefficient vector Wc _l (i), that is, at both ends of the OFDM signal band.
It is possible to reduce the error at the end of the OFDM signal band of the combined weighting coefficient vector by packing and extrapolating the weight applied to the pilot signal at the end of the band instead of packing the 0 vector. The state of extrapolation is shown in FIG. That is, in FIG. 9, the following equations (23)-
As shown in (25), at the left end of the OFDM signal band (N
-K-1) / 2 insert a vector A consisting of two elements,
At the right end of the OFDM signal band, {(NK-1) /
A state in which a vector B composed of 2} +1 elements is inserted is shown. The vector represented by the following equation (23) will be referred to as a coefficient vector Wc _l (i) again.

[0051]

[Equation 16]

[0052] IFFT for each branch to this was coefficient vector shown in equation (23) the above formed Wc _l (i)
Apply processing. The vector obtained by this IFFT processing is called impulse response vector h _l . In other words,
The coefficient vector Wc _l (i) is transformed as defined by the following equation (26) to generate the impulse response vector h _l .

[Equation 17]

Here, the impulse response vector h _l is defined as shown in the following equation (27).

[Equation 18] An example of the impulse response vector h _l is schematically shown in FIG. 10 as a curve indicated by the reference symbol 1001.

The following processing is performed in order to remove so-called aliasing. Before entering the description of the process, the filter coefficient vector f is defined by the following equation (28).

[Formula 19] An example of the filter coefficient vector f is shown in FIG.
It is schematically shown as a curve indicated by 02.

In order to remove aliasing, the impulse response vector h _l and the filter coefficient vector f are multiplied by each element as shown in the following equation (29), and FFT processing is performed (the symbol "●" in the following equation). , "Shall represent the product of each element.).

[Equation 20]

As a result, the interpolated composite weighting coefficient vector Wc _l (i) is generated. The thus synthesized weighting coefficient vector Wc _l: (i) by generating for all branches, is interpolated from the data of the composite weighting coefficient vector Wc _l of all branches that are generated (i) to the carrier shaft direction Combined weighting coefficient vector Wb _k
(i) can be generated.

Next, the convolutional interpolation method will be described.
First, the impulse response vector g of the filter coefficient vector f (hereinafter referred to as the impulse response vector g of f ) is defined by the following equation (30).

[Equation 21] Then, the impulse response vector g of f is given by the following equation (3
It will be expressed as the vector shown in 1).

[Equation 22]

If the characteristic of the filter coefficient vector f is not rectangular but is gradually attenuated toward 0 at both ends, the characteristic of the impulse response vector g of f is also a characteristic that zeros are continuous at both ends, The number of elements of the impulse response vector g of f can be reduced from N to M as shown in the following Expression (32).

[Equation 23]

Using the impulse response vector g of f thus defined and the coefficient vector Wc _l (i) defined by the above equation (19), a convolution operation is performed as shown in the following equation (33). As a result, the combined weighting coefficient W _{l, k} (i) specified by the arbitrary carrier number k and the arbitrary branch number 1 can be generated.

[Equation 24]

[0060] w _l, by substituting the _k (i), synthesized weighting coefficients are interpolated to the carrier axis of such synthetic weighting factor was produced in W _{l, k} (i) the above equation (5) The vector wb _k (i) can be generated. The interpolation method in the carrier axis direction may be a method other than the above method.

Inter-carrier interpolating means 278 receives the composite weighting coefficient vector interpolated in the symbol axis direction output from inter-symbol interpolating means 277, and uses the above linear interpolation method, FFT interpolation method, convolutional interpolation method. It is a means for generating a composite weighting coefficient vector wb _k (i) interpolated in the carrier axis direction by another interpolation method and outputting it to the carrier combining means 120.

As described above, the OFDM signal combining receiving apparatus 100 according to the first embodiment of the present invention is
By allowing the signals from the array antenna to be optimally combined for each subcarrier of the OFDM signal based on the P signal, the signal of the desired wave can be generated even under the condition that frequency selective distortion occurs due to mixing of multipath components. Can be reproduced well.

FIG. 3 is a block diagram showing a schematic configuration of an OFDM signal combining receiving apparatus 300 according to the second embodiment of the present invention. The OFDM signal combining receiving apparatus 300 according to the second embodiment has an RLS (Recursive Least Squa).
res) algorithm is applied to generate a composite weighting coefficient. Hereinafter, description will be given with reference to the drawings.

The OFDM signal synthesizing receiver 100 has antenna branches 0 to (L-1), fast Fourier transform (hereinafter referred to as FFT) means 101 (0) to 101 (L-1), It is composed of pilot carrier extracting means 110, carrier synthesizing means 120, pilot carrier synthesizing means 330, coefficient updating means 340, difference calculating means 150, pilot signal generating means 160, inter-symbol interpolation means 277 and inter-carrier interpolation means 278. .

Note that the OFDM signal synthesizing receiver 300
Of the means for configuring the first embodiment of the present invention.
Constituent Means in OFDM Signal Combining Receiver 100
Those that perform the same processing as in
Will be omitted. Also, the OFDM signal vectoru
_k(i), synthetic weighting coefficient vectorwb _k(i), SP signal
In the first embodiment of the present invention, such as carrier number kp of
The same symbols and terms as those defined in
The same definition is applied to the second embodiment.

In the second embodiment of the present invention, OF
The synthesized signal y _k (i) of the DM spectrum is expressed by the following equation (34)
Define as shown in.

[Equation 25] The generation of the combined signal y _k (i) is related to the combined weighting coefficient vector of the symbol number (i-4) because the symbol number i
The symbol number in which the SP signal immediately before is present is (i-4)
That's why.

Hereinafter, this composite weighting coefficient vector wb _k
A method of generating (i) will be described. First, SP
Generation of the composite weighting coefficient vector wb _kp (i) of the signal will be described. The composite weighting coefficient vector of the SP signal is generated by applying the RLS algorithm as shown in the following Expression (35).

[Equation 26]

Here, k _kp (i) is a gain vector defined as shown in the following equation (36), and ξ _kp (i)
Is the pre-estimation error defined as shown in equation (37) below.

[Equation 27]

However, λ ⁻¹ is a forgetting coefficient, and P _kp (i)
Is an L × L correlation inverse matrix defined as shown in the following Expression (38), and d _kp (i) is a reference composite value defined in the first embodiment of the present invention.

[Equation 28]

Similar to the first embodiment of the present invention, hereinafter, unless otherwise specified, a signal such as an OFDM signal vector or the like to which an argument such as a subscript such as a branch number 1 or a symbol number i is attached, or the like. , Is described as input / output, the subscripts, arguments, etc. necessary for identifying the input / output are assumed to be input / output according to the signal etc., and the description thereof will be omitted.

The pilot carrier combining means 330 outputs each OF output from the pilot carrier extracting means 110.
DM signal vector u _k (i) and coefficient updating means 34 described later.
The composite weighting coefficient vector wb _kp (i−
4) and the input, the combined signal y _kp (i) is generated based on the above equation (34) and output to the difference calculation means 150, and the input combined weighting coefficient vector wb _kp (i−
4) to the interpolating means 170, and the information of the symbol number i and the information of the carrier number k _p to the pilot signal generating means 160.

The coefficient updating means 340 is an OFDM signal vector output from the pilot carrier extracting means 110.
u _kp (i) and the prior estimation error ξ _kp (i) output from the difference calculation means 150 are input, and the above equations (35) to
Based on (38), the composite weighting coefficient vector wb _kp (i
-4) is updated, and the combined weighting coefficient vector wb _kp (i) obtained by the update is output to the pilot carrier combining means 330. Here, when the updating process at the symbol number i-4 is completed, the coefficient updating unit 340 stores the combined weighting coefficient vector wb _kp (i) obtained by the updating process for the next process. But good. As the value of the combined weighting coefficient vector used for the update process performed first, a predetermined value may be recorded or may be generated by another method.

Intersymbol interpolating means 277 receives as inputs the combined weighting coefficient vectors wb _kp (i-4) and wb _kp (i) output from pilot carrier combining means 330,
A composite weighting coefficient vector wb _kp (i− for SP signals with symbol numbers between symbol numbers i−4 and i
3), wb _kp (i-2), and wb _kp (i-1) may be generated as the values shown in the following formula (7) or the following formulas (8) to (12). Composite weighting coefficient vectors wb _kp (i-1), wb _kp (i-2), wb obtained by interpolation
The information of _kp (i-3) is output to inter-carrier interpolation means 278. Regarding the interpolation method in the symbol axis direction,
A method other than the above method may be used.

The second embodiment of the present invention also includes the first embodiment of the present invention.
As in the first embodiment, the compensation in the symbol axis direction is performed.
It is possible to use the latest value retention method and the linear interpolation method as the
it can. Of course, other methods may be used.
And. In the second embodiment of the present invention, the latest value holding
The method is based on the above equation (3
8) Composite weighting coefficient vectorwb _kpValue of (i)
Is the composite weighting coefficient vectorwb _kp(i-1),wb
_kp(i-2),wb _kp(i-3) is substituted. Word
It goes without saying that the composite weighting shown in equation (38) above
Coefficient vectorwb _kp(i) is update processing in the symbol axis direction
It was obtained by. In addition, the symbol number (i
-1), (i-2),and (i-3) is the thin before update
At a point between the symbol number i-4 and the updated symbol number i.
It

[Equation 29]

Next, the linear interpolation method first generates Δ wb _kp (i) according to the following equation (40), and synthesizes weights for SP signals of symbol numbers between symbol numbers i and i-4. Coefficient vectors wb _kp (i-1), wb _kp (i-
2), and the value of wb _kp (i-3) is calculated according to equations (41) to (43).

[Equation 30]

By this interpolation in the symbol axis direction, the SP signal being inserted in the carrier axis direction in the 12-carrier cycle at the time of reception is equivalent to the SP signal being inserted in the 3-carrier cycle. That is, the supplemented SP carrier number is represented by the following equation (44) instead of the above equation (1).

[Equation 31] Here, p is a non-negative integer like the above-mentioned formula (1).

Intersymbol interpolating means 277 receives as inputs the combined weighting coefficient vectors wb _kp (i) and wb _kp (i-4) output from pilot carrier combining means 330,
Composite weighting coefficient vectors wb _kp (i-1), wb _kp (i-2), w of symbol numbers between symbol numbers i and i-4
The value of b _kp (i-3) may be generated as the value shown in the above equation (39) or the above equations (40) to (44). Composite weighting coefficient vector w obtained by interpolation
The information of b _kp (i-1), wb _kp (i-2), and wb _kp (i-3) is output to inter-carrier interpolation means 278. The interpolation method in the symbol axis direction may be a method other than the above method.

Next, as specific examples of the interpolation method in the carrier axis direction, three methods of the linear interpolation method, the FFT interpolation method, and the convolutional interpolation method will be described. First, the linear interpolation method will be described. By the interpolation in the symbol axis direction, the SP signal is inserted in the carrier axis direction in three carrier cycles. In the linear interpolation method, δ wb _kp (i-4) is first generated according to the following equation (45), and carrier numbers k _p and k _p +
The values of the composite weighting coefficient vectors wb _{kp + 1} (i-4) and wb _{kp + 2} (i-4) for the SP signals with carrier numbers between 3 and 3 are calculated according to equations (45) to (47). It is a thing.

[Equation 32]

By this interpolation in the carrier axial direction, all S
The composite weighting coefficient vector wb _k (i) for the P signal is determined. Next, the FFT interpolation method will be described. The combined weighting coefficient vector wb _k (i-4) was composed of L elements in the branch axis direction, as shown in the above equation (5). It is defined here by the synthesis weighting factor of the carrier axis vector wc _l (i-4) the following equation (48).

[Expression 33]

[0080] Here, among the components of the carrier shaft direction of the resultant weighting coefficient vector wc _l (i-4), the elements identified by the carrier number other than SP carrier number shown in the above formula (44) Fill with 0. That is, using W _{l, k} (i-4) shown in the following equation (49), a coefficient vector Wc _l (i-4) having a configuration as shown in the following equation (50) is obtained.
Is defined. Note that this is called zero interpolation.

[Equation 34]

Next, an inverse fast Fourier transform (hereinafter referred to as IFFT) is performed on the coefficient vector Wc _l (i-4).
ourier Transform). ) Perform processing. At that time, I
The number of points for FFT processing is N = 2 ⁿ . Here, ν is a natural number, and the condition of N> K is satisfied. The impulse number (integer), which is the number given to an arbitrary impulse obtained after the IFFT processing, is n. Here, let the range of n be the range shown in the following formula (51).

[Equation 35]

Here, in order to make the coefficient vector Wc _l (i-4) a coefficient vector of N points, the coefficient vector W
the left end of the _{c l (i-4) (} N-K-1) / 2 pieces of inserting a zero vector of zero, the right end of the coefficient vector _{Wc l (i-4) {} (N-K-1) A zero vector consisting of / 2} +1 zeros is inserted to generate a coefficient vector shown in the following equation (52).

[Equation 36] Here, 0 is a 0 vector defined by the following equation (53).

[Equation 37]

[0083] As shown in equation (52), the end of the coefficient vector Wc _l (i-4), i.e. rather than pack the 0 vector on the OFDM signal band ends, 0 vector pilot end of the band instead of By weighting and extrapolating the weight applied to the signal, the OFDM of the composite weighting coefficient vector
The error at the signal band edge can be reduced. The state of extrapolation is shown in FIG. That is, in FIG. 9, the following equation (54)
~ (56), a vector A consisting of (N-K-1) / 2 elements is inserted at the left end of the OFDM signal band, and {(N-K-1) at the right end of the OFDM signal band. )
A state in which a vector B composed of / 2} +1 elements is inserted is shown. Incidentally, hereafter referred to as formula (54) to the newly coefficient vector a vector indicating Wc _l (i-4).

[0084]

[Equation 38]

In the above equation (54) thus formed,
Coefficient vector to indicateWc _lIF for each branch for (i-4)
FT processing is performed. The vector obtained by this IFFT process
Cuttle impulse response vectorh _lIt is called (i-4).
In other words, the coefficient vectorWc _l(i-4) is expressed by the following equation (5
Impulse response vector after conversion defined in 7)h
_l(i-4) is to be generated.

[Formula 39]

Here, the impulse response vector h _l (i-
4) is defined as shown in the following equation (58).

[Formula 40] An example of the impulse response vector h _l (i-4) is schematically shown in FIG. 10 as a curve indicated by the reference symbol 1001.

In order to remove so-called aliasing, the following processing is performed. Before entering the description of the processing, the filter coefficient vector f is defined by the following equation (59).

[Formula 41] An example of the filter coefficient vector f is shown in FIG.
It is schematically shown as a curve indicated by 02.

In order to remove the aliasing, the impulse response vector h _l (i-
4) and the filter coefficient vector f are producted element by element,
FFT processing is performed (the symbol "●" in the following equation represents the product of each element).

[Equation 42]

As a result, the interpolated composite weighting coefficient vector Wc _l (i) is generated. The thus synthesized weighting coefficient vector Wc _l: (i) by generating for all branches, is interpolated from the data of the composite weighting coefficient vector Wc _l of all branches that are generated (i) to the carrier shaft direction Combined weighting coefficient vector Wb _k
(i) can be generated.

Next, the convolutional interpolation method will be described.
First, the impulse response vector g of the filter coefficient vector f (hereinafter referred to as the impulse response vector g of f ) is defined by the following equation (61).

[Equation 43] Then, the impulse response vector g of f is expressed by the following equation (6
It will be expressed as the vector shown in 2).

[Equation 44]

When the characteristic of the filter coefficient vector f is not rectangular but is gradually attenuated toward 0 at both ends, the characteristic of the impulse response vector g of f is such that almost zero is continuous at both ends, The number of elements of the impulse response vector g of f can be reduced from N to M as shown in the following equation (63).

[Equation 45]

[0092] the convolution as shown in this way defined f impulse response vector g and the formula (50) in a defined coefficient vector Wc _l (i-4) using the following equation (64) calculating By doing, it is possible to generate the combined weighting coefficient W _{l, k} (i-4) specified by the arbitrary carrier number k and the arbitrary branch number 1.

[Equation 46]

[0093] By substituting the thus synthesized weighting coefficient generated by _{W l, k (i-4} ) w l of the above equation _{(5), k (i-} 4), it is interpolated to the carrier axis It is possible to generate the combined weighting coefficient vector wb _k (i-4). The interpolation method in the carrier axis direction may be a method other than the above method.

Inter-carrier interpolating means 278 receives the composite weighting coefficient vector interpolated in the symbol axis direction output from inter-symbol interpolating means 277, and uses the above linear interpolation method, FFT interpolation method, convolutional interpolation method. This is a means for generating a composite weighting coefficient vector wb _k (i-4) interpolated in the carrier axis direction by another interpolation method and outputting it to the carrier combining means 120.

As described above, the OFDM signal combining receiving apparatus 300 according to the second embodiment of the present invention is
By allowing the signals from the array antenna to be optimally combined for each subcarrier of the OFDM signal based on the P signal, the signal of the desired wave can be generated even under the condition that frequency selective distortion occurs due to mixing of multipath components. Can be reproduced well.

FIG. 4 is a block diagram showing a schematic configuration of an OFDM signal combining receiver 400 according to the third embodiment of the present invention. OFD of the third embodiment of the present invention
The M-signal combining receiver 400 is for combining and outputting OFDM signals from the respective branches in the time domain. Hereinafter, description will be given with reference to the drawings.

The OFDM signal combining receiver 400 has antenna branches (hereinafter simply referred to as branches) 0 to.
(L-1), fast Fourier transform (hereinafter, FFT (Fast F
ourierTransform). ) Means 101 (0) -10
1 (L-1), pilot carrier extracting means 110, time domain combining means 420, pilot carrier combining means 1
30, coefficient update means 440, difference calculation means 150, pilot signal generation means 160, interpolation means 470, and inverse fast Fourier transform (hereinafter referred to as IFFT (Inverse Fast Fou).
rier Transform). ) Means 481 (0) to 481
(L-1).

The OFDM signal synthesizing receiver 400
Of the means for configuring the first embodiment of the present invention.
Constituent Means in OFDM Signal Combining Receiver 100
Those that perform the same processing as in
Will be omitted. Also, the OFDM signal vectoru
_k(i), synthetic weighting coefficient vectorwb _k(i), SP signal
Carrier number k_pEtc. in the first embodiment of the present invention
The same symbols and terms as those defined in
The same definition is applied to the second embodiment.

The IFFT means 481 (0) is a composite weighting coefficient vector output from the interpolation means 470 described later.
IFb processing is applied to the input synthetic weighting coefficient vector wb _k (i) and the like by inputting wb _k (i) and the like, and IF
It is a means for extracting a filter coefficient (hereinafter referred to as a transversal filter coefficient) necessary for the filter processing in the time domain from the vector obtained by the FT processing and outputting it to the time domain synthesizing means 420.

It should be noted that the composite weighting coefficient vector wb _k (i), etc. input to the IFFT means 481 (0), and the IF
The transversal filter coefficient output from the FT means 481 (0) is for filtering the OFDM signal output from the branch 0. IFFT means 4
81 (1) to 481 (L-1) are IFFT means 481.
It is a means for performing the same processing as (0), and is for filtering the OFDM signals output from the branches 1 to (L-1), respectively.

The time domain synthesizing means 420 has branches 0 to 0.
The OFDM signal output from (L-1) and the transversal filter coefficients output from the IFFT units 481 (0) to 481 (L-1) are input, and each branch is input according to the input transversal filter coefficient. O from
It is a means for performing filter processing on the FDM signal in the time domain, and combining and outputting the signals of the respective branches after the filter processing.

Specifically, the input OFDM signal U
_By performing the conversion shown in the following Expression (65) on _l (nt), each branch and each carrier (since processing in the time domain, it is not clearly displayed in Expression (65)). A combined signal Y (nt) that is filtered in the time domain and combined for all branches is generated.

[Equation 47] However, nt is an arbitrary time number (where n is an integer), l is an arbitrary branch number, and h _{l, m} (i) (0 ≦
m ≦ M−1, and M is the transversal filter 52.
It is the number of taps from 1 (0) to 521 (L-1). ) Is the transversal filter coefficient, and i is the symbol number.

It should be noted that the OFDM signal combining receiving device 400
May be configured like the OFDM signal combining receiver 500 shown in FIG. 5, and the time domain combining means 420 may be formed by the transversal filters 521 (0) to 521 (L-1) and the adding means 522. .

In that case, the transversal filter 52
1 (0) to 521 (L-1) are output from the OFDM signals output from the branches 0 to (L-1) and the IFFT units 481 (0) to (L-1), respectively, as shown in FIG. The input transversal filter coefficient is input, the input OFDM signal is subjected to filter processing in the time domain for each branch, and the result is output to the adding means 522. The adding means 522 is configured by the transversal filters 521 (0) to 521 (0)-
The respective filtered results output from 521 (L-1) are added and output to the outside.

Below, the receiving device 50 for OFDM signal combining is described.
0 is configured like the OFDM signal combining receiver 600 shown in FIG. 6, and the interpolating means 470 is used as the inter-symbol interpolating means 67.
1 and inter-carrier interpolating means 672. In this case, inter-symbol interpolating means 671, inter-carrier interpolating means 672, and IFFT means 481 (0).
~ 481 (L-1) performs the following processing.

The inter-symbol interpolating means 671 receives the synthetic weighting coefficient vector wb _kp (i) output from the pilot carrier synthesizing means 130, and receives the above-mentioned first embodiment of the present invention.
The inter-symbol interpolation processing (for example, Expression (8) or Expressions (9)-(12)) described in the embodiment of
It outputs to inter-carrier interpolating means 672.

Inter-carrier interpolating means 672 receives as input the composite weighting coefficient vector wb _kp (i) obtained by the inter-symbol interpolation processing, and performs a predetermined interpolation processing in the carrier axis direction to carry out the composite weighting coefficient vector wb. _k (i) is generated and IFFT means 481 (0) to 481 (L-1)
Output to. Here, as the “predetermined interpolation process”, for example, a linear interpolation process (formulas (14) to (16)) and the convolutional interpolation method (formulas (30) to (33)) described in the first embodiment of the present invention. ), There are other methods, but the type of the method does not matter.

The IFFT means 481 (0) -48 will be described below.
The processing performed by 1 (L-1) will be specifically described. Here, the combined weighting coefficient vector wb _k (i) after interpolation output from the inter-carrier interpolation means 672 is shown in the following equation (66).

[Equation 48]

Also, the number of data items to be subjected to IFFT processing
(Also referred to as the number of points) is N = 2 ^νAnd However,
ν is a natural number and the condition N> K is satisfied.
To do. Arbitrary impulse obtained by IFFT processing
Is n. The range of n is shown in the following formula (67).
Range.

[Equation 49]

Here, the coefficient vectorWc _l(i) N point
Coefficient vectorWc
_lAt the left end of (i) is a zero vector consisting of (NK-1) / 2 zeros.
Insert cutler, coefficient vectorWc _lAt the right end of (i), {(N
-K-1) / 2} Insert zero vector consisting of one zero
Then, the coefficient vector shown in the following equation (68)
Coefficient vector toWc _l(i). ) Is generated.

[Equation 50] Here, 0 is a 0 vector defined by the following equation (69).

[Equation 51]

Next, the coefficient vector Wc _l (i) is subjected to IFFT processing as shown in the following equation (70) to generate a coefficient vector of the transversal filter.

[Equation 52] The coefficient vector of the transversal filter obtained above is set as in the following expression (71).

[Equation 53]

The equation (71) can be rewritten as the following equation (72), paying attention to the M consecutive elements of the above equation (71).

[Equation 54] From N transversal filter coefficients, the continuous elements in the vector h _l are extracted by the tap length of the transversal filter (this tap length is M), and the following expression (73) is used as an M-dimensional vector. , Transversal filter coefficient vector.

[Equation 55]

By performing the above processing, the transversal filter coefficient vector h _l with the number of taps M is generated. In this way, IFFT means 481 (0) to 481
(L-1) generates a transversal filter coefficient vector h _l for each branch launch, and the corresponding transversal filters 521 (0) to 521 (L-
Output to 1).

Also, the receiving device 500 for OFDM signal synthesis
Is configured as the OFDM signal combining receiving apparatus 700 shown in FIG. 7, and the interpolating means 470 is replaced by the inter-symbol interpolating means 671.
It may be constituted by the zero insertion means 772 and the zero insertion means 772. In this case, the zero insertion means 772 and the IFFT means 481
The processing performed by (0) to 481 (L-1) will be specifically described below.

The zero insertion means 772 receives as input the combined weighting coefficient vector wb _kp (i) which has been subjected to inter-symbol interpolation processing (for example, expression (8) or expressions (9)-(12)). The combined weighting coefficient vector wb _kp (i) is subjected to the zero insertion processing (equations (17) to (25)) described in the first embodiment of the present invention, and the coefficient vector Wc _l (i) ( Formula (23)-(25)) is generated, and IFF is generated.
It outputs to the T means 481 (0) to 481 (L-1).

IFFT means 481 (0) to 481 (L-
1) is the coefficient vector obtained by the zero insertion process
IFFT processing (equation (26)) is applied to Wc _l (i),
An impulse response vector (equation (27)) is generated. The formula (27) is described below again.

[Equation 56]

The equation (27) can be rewritten as the following equation (74) by paying attention to the M consecutive elements of the above equation (27).

[Equation 57]

From the N impulse response vectors, the continuous elements in the vector h _l are extracted by the tap length of the transversal filter (this tap length is M), and the equation (75) M-dimensional shown below is extracted. And a transversal filter coefficient vector.

[Equation 58] As a result, the coefficient h _l of the M-tap transversal filter was obtained.

By performing the above processing, the transversal filter coefficient vector h _l having the tap number M is generated. In this way, IFFT means 481 (0) to 481
(L-1) generates a transversal filter coefficient vector h _l (Equation (75)) for each branch launch, and the corresponding transversal filter 521 (0) is generated.
To 521 (L-1). Incidentally, inter-carrier interpolating means 672 and IFFT means 481 (0) to 481.
The processing performed in (L-1) corresponds to the FFT interpolation method described in the first embodiment of the present invention.

The description of the third embodiment of the present invention has been made for the case where the LMS algorithm is applied. However, even when the RLS algorithm is applied, the above-mentioned results obtained by applying the LMS algorithm (for example, The argument of the transversal filter coefficient shown in equations (73) and (75) only changes from (i) to (i-4), and the other parts do not substantially change.

As described above, the OFDM signal combining receivers 400 and 50 according to the third embodiment of the present invention.
Nos. 0, 600, and 700 enable the signal from the array antenna to be optimally combined for each subcarrier of the OFDM signal based on the SP signal, thereby causing frequency selective distortion due to mixing of multipath components. The desired signal can be reproduced well even under the circumstances.

[0122]

As described above, the present invention realizes an OFDM signal synthesizing receiver capable of satisfactorily reproducing a signal of a desired wave even in a situation where frequency selective distortion due to mixing of multipath components occurs. You can

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of the configuration of an OFDM signal combining receiver according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing an example of a configuration of an OFDM signal combining receiver according to the first embodiment of the present invention.

FIG. 3 is a block diagram showing an example of a configuration of an OFDM signal combining receiver according to a second embodiment of the present invention.

FIG. 4 is a block diagram showing an example of the configuration of an OFDM signal combining receiver according to a third embodiment of the present invention.

FIG. 5 is a block diagram showing an example of a configuration of an OFDM signal combining receiving apparatus according to a third embodiment of the present invention.

FIG. 6 is a block diagram showing an example of a configuration of an OFDM signal combining receiver according to a third embodiment of the present invention.

FIG. 7 is a block diagram showing an example of a configuration of an OFDM signal combining receiving device according to a third embodiment of the present invention.

FIG. 8 is a diagram showing an array of signals forming an OFDM signal in a carrier-symbol space.

FIG. 9 is a diagram for explaining an extrapolation method of a synthetic weighting coefficient according to the present invention.

FIG. 10 is a diagram for explaining an interpolation method using FFT according to the present invention.

[Explanation of symbols]

0- (L-1) antenna branches 100, 200, 300, 400, 500, 600, 7
00 OFDM signal combining receiver 101 (0) to (L-1) fast Fourier transform (FF
T) means 110 pilot carrier extracting means 120 carrier synthesizing means 130, 330 pilot carrier synthesizing means 140, 340, 440 coefficient updating means 150 difference calculating means 160 pilot signal generating means 170 interpolating means 277 inter-symbol interpolating means 278 inter-carrier inter-carrier Insertion means 420 Time domain synthesis means 470 Interpolation means 481 (0) to (L-1) Inverse fast Fourier transform (FF
T) means 521 (0) to (L-1) transversal filter 522 adding means 671 inter-symbol interpolation means 672 inter-carrier interpolation means 772 zero insertion means 1001 impulse response vector 1002 filter coefficient vector

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Koichiro Imamura             1-10-11 Kinuta, Setagaya-ku, Tokyo, Japan             Broadcasting Association Broadcast Technology Institute (72) Inventor Kazuhiko Shibuya             1-10-11 Kinuta, Setagaya-ku, Tokyo, Japan             Broadcasting Association Broadcast Technology Institute F term (reference) 5K022 DD01 DD13 DD18 DD33

Claims (6)

[Claims] 1. A plurality of antenna branches forming a receiving antenna each receive an OFDM signal, and for identifying signals among the signals forming the OFDM signal, the signals being compared with each other between the antenna branches, In a receiving device for synthesizing the same signal, both the symbol number and the carrier number which is the subcarrier number, for the OFDM signal received for each antenna branch,
From the OFDM spectrum for each antenna branch, a means for performing a fast Fourier transform process to generate an OFDM spectrum, and a scattered
The pilot carrier extraction means for extracting the SP signal which is a pilot signal, and the SP signals specified by the same symbol number and the same carrier number
Pilot carrier synthesizing means for multiplying each subcarrier by a synthetic weighting coefficient according to a carrier number for specifying a P signal and a branch number which is an antenna branch number, and generating a synthetic signal by the subcarrier, Pilot signal generating means for generating a reference combined value that is predetermined information regarding a value indicated by the SP signal specified by a symbol number for specifying a signal and a carrier number for specifying the combined signal, An estimation error that is a value obtained by subtracting the value indicated by the combined signal having the same symbol number and carrier number for specifying the reference combined value and the combined signal from the reference combined value is generated. Means, an estimation error, and an SP carrier which is a subcarrier to which the SP signal is assigned. A coefficient updating unit for generating a combined weighting coefficient for each antenna branch for each SP carrier according to the number, and a symbol number and a carrier number based on each combined weighting coefficient generated by the coefficient updating unit. Interpolation means for performing a predetermined interpolation process to generate a combined weighting coefficient vector which is a combined weighting coefficient vector specified by the same symbol number and the same branch number, and which has the combined weighting coefficient corresponding to the carrier number as an element And the OFD
A value obtained by multiplying each signal forming the M signal by a composite weighting coefficient specified by the symbol number and the carrier number equal to the symbol number and the carrier number for specifying the signal forming the OFDM signal is used as the carrier. And a carrier combining means for generating a combined signal by adding in the number direction, and the predetermined combining weighting coefficient applied by the pilot carrier combining means is
An OFDM signal synthesizing receiving device, which is a synthesizing weighting coefficient generated by the coefficient updating means. 2. A plurality of antenna branches forming a receiving antenna each receive an OFDM signal, and for identifying signals among the signals forming the OFDM signal, the signals being compared with each other between the antenna branches, In a receiving device for synthesizing the same signal, both the symbol number and the carrier number which is the subcarrier number, for the OFDM signal received for each antenna branch,
From the OFDM spectrum for each antenna branch, a means for performing a fast Fourier transform process to generate an OFDM spectrum, and a scattered
The pilot carrier extraction means for extracting the SP signal which is a pilot signal, and the SP signals specified by the same symbol number and the same carrier number
A pilot carrier synthesizing unit for multiplying each subcarrier by a synthetic weighting coefficient according to a carrier number for specifying a P signal and a branch number which is an antenna branch number, and adding the resultant for each subcarrier, and the synthetic Pilot signal generating means for generating a reference combined value that is predetermined information regarding a value indicated by the SP signal specified by a symbol number for specifying a signal and a carrier number for specifying the combined signal; An estimation error that is a value obtained by subtracting the value indicated by the combined signal having the same symbol number and carrier number for specifying the reference combined value and the combined signal from the reference combined value is generated. Means, an estimation error, and an SP carrier which is a subcarrier to which the SP signal is assigned. Coefficient updating means for generating a combined weighting coefficient for each antenna branch for each SP carrier according to the number, and combining for each antenna branch for each SP carrier generated by the coefficient updating means By performing a predetermined interpolation process on the weighting factor, a synthetic weighting factor for the data carrier that is a subcarrier other than the SP carrier is generated, and converted to a synthetic weighting factor for each carrier for each antenna branch. Then, interpolation means for performing an inverse Fourier transform process to generate a filter coefficient vector, and the filter corresponding to the value indicated by the signal of each carrier forming the OFDM signal of the same symbol number for each antenna branch Perform predetermined convolution integration with coefficient vector and add A time-domain synthesizing means for generating a synthesized signal by means of the above, and the predetermined synthesis weighting coefficient applied by the pilot carrier synthesizing means is a synthesis weighting coefficient generated by the coefficient updating means. Receiver for OFDM signal synthesis. 3. The coefficient updating means is an LMS (Least Mean).
Square algorithm or RLS algorithm (Recurs
3. The O according to claim 1 or 2, wherein the composite weighting coefficient is generated based on (ive Least Squares).
Receiver for FDM signal synthesis. 4. The filter coefficient vector is a transversal filter coefficient vector, the time domain synthesizing means is composed of a transversal filter and an adding means, and the transversal filter is the transversal filter for each antenna branch. 3. A predetermined convolution integration process of a filter coefficient vector and a value indicated by the OFDM signal is performed, and the adding means integrates the values obtained by the convolution integration process to obtain a combined signal. The receiving device for OFDM signal synthesis described. 5. The interpolating means is composed of inter-symbol interpolating means and inverse Fourier transforming means, and the inter-symbol interpolating means performs a predetermined interpolating process on a symbol number with respect to the composite weighting coefficient. The inverse Fourier transform means is means for performing an inverse Fourier transform process on the combined weighting coefficient vector subjected to the interpolation process for the symbol number to generate the transversal filter coefficient vector. The receiver for OFDM signal combination according to claim 4, characterized in that 6. The interpolating means is composed of inter-symbol interpolating means, inter-carrier interpolating means and inverse Fourier transforming means, and the inter-symbol interpolating means is predetermined with respect to a symbol number for a composite weighting coefficient. Is a means for performing an interpolation process, the inter-carrier interpolation means, for the composite weighting coefficient vector obtained by the interpolation process,
Means for performing a predetermined interpolation processing on the carrier number, the inverse Fourier transform means, the interpolation processing is performed on the symbol number, and for the composite weighting coefficient vector subjected to the interpolation processing on the carrier number 5. The OFDM signal synthesizing receiver according to claim 4, which is means for performing inverse Fourier transform processing to generate the transversal filter coefficient vector.