JP2008078916A - Ofdm broadcast receiver and ofdm broadcast relay device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an OFDM broadcast receiver and an OFDM broadcast relay device in which a circuit scale is effectively reduced, which has no delay and is applicable also to an SFN in a broadcast relay device which relays a broadcasting signal. <P>SOLUTION: In the OFDM broadcast receiver 100, eigenvalue decomposition is performed to receiving signals of respective receiving antennas 1-1 to 1-N by an eigenvalue decomposition part 4, an eigenvalue and an eigenvector corresponding to the eigenvalue are calculated, synthetic weight is generated by a synthetic weight generation part 5 from the eigenvector, the receiving signals are weighted and synthesized based on the synthetic weight by beam synthesizing parts 6-1 to 6-N and diversity-synthesizes an output from the beam synthesizing parts 6-1 to 6-N by a diversity synthesizing part 7. Thus, in the relay device equipped with the receiver 100, the circuit scale is reduced and a processing delay is eliminated in comparison with a conventional relay device. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an OFDM broadcast receiving apparatus that receives a digital broadcast signal by an Orthogonal Frequency Division Multiplexing (OFDM) system and an OFDM broadcast relay apparatus that retransmits the received signal.

  Currently, in Japanese terrestrial digital television broadcasting, a standard called ISDB-T (Integrated Services Digital Broadcasting for Terrestrial) is established, and by adopting the OFDM method as a modulation method, the information transmission speed is increased. In addition, it provides images without ghosting. In the OFDM system, modulation is performed by assigning data to each of a plurality of subcarriers orthogonal to each other on the frequency axis (in ISDB-T mode 3, the number of subcarriers is 5617). The transmitting side of the OFDM wireless communication system performs an inverse fast Fourier transformation (IFFT) process for converting the frequency domain signal into the time domain signal, and the receiving side converts the time domain signal to the frequency domain signal. A fast Fourier transformation (FFT) process for returning the signal is performed.

  Conventional interference cancellation techniques include diversity techniques for improving reception characteristics and multipath interference cancellation in fading environments, multipath interference and adaptive array antenna technology that eliminates interference waves on the same channel that do not correlate with the desired signal, A sneak interference removal technique for removing sneak interference in a single frequency network (SFN) broadcast wave relay station is known.

By the way, as described in Patent Document 1, some conventional OFDM broadcast relay apparatuses perform diversity combining. In a conventional relay apparatus using diversity, an OFDM signal is input as a received signal of one or more systems from a receiving unit, and is converted into a baseband digital signal and subjected to fast Fourier transform through quadrature detection. The fast Fourier transformed signal is diversity synthesized and subjected to inverse fast Fourier transform. Thereafter, the OFDM signal is retransmitted after being subjected to quadrature modulation and conversion to a desired frequency in the transmission unit. In this relay station transmitting / receiving apparatus, the frequency response of the transmission path for each system is calculated from the carrier data for each system, and the weighting coefficient corresponding to the carrier used for diversity combining is calculated from this frequency response.
JP 2002-271291 A

  As described above, in the relay device using diversity as disclosed in Patent Document 1, the reception performance is excellent, but as the number of antennas increases, the carrier used for the fast Fourier transform and diversity combining in the subsequent stage The amount of calculation of the corresponding weighting factor increases. For this reason, in a wireless communication system using 5000 or more subcarriers as in terrestrial digital broadcasting, the circuit scale of the receiver becomes enormous.

  In addition, in order to perform fast Fourier transform and inverse fast Fourier transform for the number of carriers, time axis data for the number of carriers is required, and in digital terrestrial broadcasting, time data for several symbols may be obtained. . Then, the delay time in the relay apparatus becomes very large, the delay time in SFN having the same reception frequency and transmission frequency does not satisfy the condition of several microseconds, and SFN does not hold.

  Accordingly, an object of the present invention is to provide an OFDM broadcast receiving apparatus and an OFDM broadcast relay apparatus that can effectively reduce the circuit scale and can be applied to SFN without processing delay.

  In order to achieve the above object, the present invention provides a plurality of receivers that receive OFDM broadcast signals, and a plurality of receivers that are arranged in a plurality of systems and that convert broadcast signals output from the plurality of receivers into digital signals. An eigenvalue for performing eigenvalue decomposition by inputting a digital signal output from each of the analog-digital conversion unit and the plurality of analog-digital conversion units, and calculating eigenvalues of the plurality of systems and eigenvectors corresponding to the eigenvalues Distributing and supplying digital signals output from the decomposing unit, a synthetic weight generating unit that generates synthetic weights based on the eigenvectors of the plurality of systems obtained by the eigenvalue decomposing unit, and the plurality of analog-digital converting units, respectively. , A plurality of beads for weighting and synthesizing the digital signal based on the synthesis weight, respectively. A combining unit, and adapted to and a diversity combining unit for diversity combining the plurality of beamforming units of each output.

  In this way, eigenvalue decomposition is performed on the received signal of each system received by each receiving unit, a composite weight is generated based on the eigenvector corresponding to the eigenvalue obtained thereby, and each system is generated using the composite weight. After the digital signals are weighted and combined, the outputs from the beam combining units are diversity combined.

  In the present invention, since the digital signal is weighted and combined using the eigenvectors of the received digital signals of each system, and then the diversity combining is performed, the baseband digital signal in the conventional relay device using diversity The fast Fourier transform process and the inverse fast Fourier transform process can be avoided, and the circuit scale can be effectively reduced and the processing delay can be avoided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing a schematic configuration of an OFDM broadcast relay apparatus according to the first embodiment of the present invention. In FIG. 1, the OFDM broadcast relay apparatus includes an OFDM broadcast reception apparatus 100, a digital-analog conversion apparatus 8 that converts a digital signal into an analog signal, an up-converter 9, and a transmission antenna 10.

  The OFDM broadcast receiving apparatus 100 includes N receiving antennas 1-1 to 1-N, down converters 2-1 to 2-N, and analog-to-digital conversion apparatuses 3-1 to 3 that convert analog signals into digital signals. -N, an eigenvalue decomposition unit 4 that calculates an eigenvalue of the digital signal and an eigenvector corresponding to the eigenvalue, a weight generation unit 5 that generates a synthesis weight based on the calculated eigenvector, and a generated synthesis weight It comprises beam combining units 6-1 to 6-N that weight and combine digital signals, and a diversity combining unit 7 that performs diversity combining. That is, in the OFDM broadcast receiving apparatus 100, the OFDM signals received by the receiving antennas 1-1 to 1-N are frequency-converted by the down converters 2-1 to 2-N, and the analog-digital converting apparatuses 3-1 to 3 are performed. -N is transmitted to the beam combining units 6-1 to 6-N. In addition, the eigenvalue decomposition unit 4 calculates the eigenvalue of the digital signal and the eigenvector corresponding to the eigenvalue from the digital signal output from the analog-digital conversion devices 3-1 to 3 -N. As a result, combined weights for the beam combining units 6-1 to 6-N are generated. The beam combining units 6-1 to 6-N weight and combine the digital signals based on the generated combining weights. This output is diversity combined by the diversity combining unit 7.

  The processing operation of the OFDM broadcast relay apparatus with the above configuration will be described.

  The RF signals in the RF (Radio Frequency) band received independently by the N receiving antennas 1-1 to 1-N are IF (Intermediate) by the down converters 2-1 to 2-N for each system. The frequency is converted into a frequency (intermediate frequency) band, and converted into a digital baseband signal through the analog-digital conversion devices 3-1 to 3 -N. A part of the OFDM signal that has become a digital baseband signal is subjected to eigenvalue decomposition in the eigenvalue decomposition unit 4. The eigenvalue decomposition unit 4 obtains a correlation matrix of received signal vectors having N received signals that are outputs of the analog-digital conversion devices 3-1 to 3-N as vectors, and obtains N eigenvalues λ1 to λN and N Eigenvectors corresponding to the eigenvalues λ1 to λN are obtained. The weight generation unit 5 generates combined weights for the N beam combining units 6-1 to 6-N based on the eigenvectors corresponding to the eigenvalues.

  Each beam combining unit receives the digital baseband signal of each system output from the analog-digital conversion devices 3-1 to 3 -N. Each beam synthesis unit weights and synthesizes the digital baseband signal based on the N synthesis weights generated by the weight generation unit 5. At this time, each beam combining unit forms a beam in which the digital baseband signals are orthogonal to each other and outputs the beam to the diversity combining unit 7.

  In the diversity combining unit 7, the signal components corresponding to the beams combined by the beam combining units are diversity combined and output to the digital-analog converter 8. At this time, for the diversity combining of the signal components corresponding to each beam, a general combining method in diversity combining such as maximum ratio combining or equal gain combining is employed.

  The digital baseband signal output to the digital-analog conversion device 8 is converted into an OFDM signal through the digital-analog conversion device 8 and the up-converter 9 and is radiated from the transmission antenna 10.

  As described above, in the first embodiment, the eigenvalue decomposition is performed on the received signal of each receiving antenna, and the digital baseband signal is weighted by the combined weight generated based on the eigenvector corresponding to the eigenvalue. The output is combined with diversity.

  Therefore, since the fast Fourier transform process and the inverse fast Fourier transform process can be avoided, the circuit scale can be reduced. Furthermore, since high-speed signal processing is possible, it is possible to prevent the failure of SFN due to processing delay, and an OFDM broadcast receiving apparatus and OFDM broadcast relay apparatus for SFN can be realized.

(Second Embodiment)
FIG. 2 is a block diagram showing a schematic configuration of an OFDM broadcast relay apparatus according to the second embodiment of the present invention. 2, the same parts as those in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted here.

  Here, the difference between the relay device in FIG. 2 and the relay device in FIG. 1 is that, in the relay device in FIG. 2, the composite weight is obtained from only the eigenvector corresponding to the maximum eigenvalue among the eigenvectors obtained by the eigenvalue decomposition unit 4. It is a point which produces | generates and weights and synthesize | combines each digital baseband signal in the beam synthesis part 6 based on the said synthetic | combination weight.

  In the relay apparatus in FIG. 2, digital baseband signals from the analog-digital conversion apparatuses 3-1 to 3 -N are output to the beam combining unit 6. The digital baseband signals from the analog-digital conversion devices 3-1 to 3-N are subjected to eigenvalue decomposition in the eigenvalue decomposition unit 4, and eigenvalues of the digital baseband signals of the respective systems and eigenvectors corresponding to the eigenvalues. Is calculated. The combined weight generation unit 5 generates a combined weight based on the eigenvector corresponding to the maximum eigenvalue among the calculated eigenvectors, and outputs it to the beam combining unit 6. The beam combiner 6 weights and synthesizes the digital baseband signal based on the generated combined weight. The synthesized signal is converted into an OFDM signal through the digital-analog converter 8 and the up-converter 9 and is radiated from the transmitting antenna 10.

  As described above, according to the second embodiment, the eigenvalue decomposition is performed on the reception signal of each antenna, and the combined weight generated from only the eigenvector corresponding to the maximum eigenvalue among eigenvectors based on the eigenvalue. Since beam combining is performed, only one beam combining unit 6 is sufficient, and the diversity combining unit 7 is not necessary.

  Therefore, the circuit scale can be further reduced and the signal processing speed can be increased as compared with the conventional relay device.

  In the OFDM broadcast receiving apparatus 100 in FIG. 2, an example in which the combined weight generation unit 5 generates a combined weight based only on the eigenvector corresponding to the maximum eigenvalue among the calculated N eigenvectors has been described. It is not necessary to generate the weight only from the eigenvector corresponding to the maximum eigenvalue, and the synthesized weight may be generated from the eigenvector corresponding to the specified number of eigenvalues from the maximum eigenvalue. The magnitude of the eigenvalues of the correlation matrix of the received vector with the signal received by each receiving antenna as a vector element reflects the power contained in each orthogonal beam, so that the desired signal is transmitted to the beam formed by the maximum eigenvalue. The power component of the second eigenvalue and the third eigenvalue are in order. Accordingly, by selecting from eigenvectors corresponding to large eigenvalues, the number of beam combining units can be reduced, and the circuit scale can be reduced.

  Note that the relay device in FIG. 2 is a stable propagation path environment with relatively small fading fluctuation, but is an optimal configuration when there is a problem in service without a diversity device.

(Third embodiment)
FIG. 3 is a block diagram showing a schematic configuration of an OFDM broadcast relay apparatus according to the third embodiment of the present invention. In FIG. 3, the same parts as those in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted here.
In the relay apparatus in FIG. 3, digital baseband signals output from the analog-digital conversion apparatuses 3-1 to 3 -N are transmitted to the beam combining unit 6. Further, the eigenvalue decomposition unit 4 calculates an eigenvalue and an eigenvector corresponding to the eigenvalue based on the outputs of the analog-digital conversion devices 3-1 to 3 -N. This eigenvector is compared with the optimum weight recorded in the memory 11 by the comparison unit 12. The result is output to the weight generator 5, and the weight generator 5 generates a combined weight for the beam combiner 6 from the weight obtained as a result of the comparison by the comparator 12. The digital baseband signal is weighted and synthesized by the beam synthesis unit 6 based on the synthesis weight. The output of the beam combining unit 6 is diversity combined by the diversity combining unit 7 and transmitted from the transmitting antenna 10 via the digital-analog conversion device 8 and the up converter 9.

The above configuration will be described more specifically.
The eigenvalue decomposition unit 4 performs eigenvalue decomposition on a part of the OFDM signal that has passed through the analog-digital conversion devices 3-1 to 3 -N and has become a digital baseband signal. The eigenvalue decomposition unit 4 obtains a correlation matrix of received signal vectors having N received signals that are outputs of the analog-digital conversion devices 3-1 to 3-N as vectors, and obtains N eigenvalues λ1 to λN and N Eigenvectors corresponding to the eigenvalues λ1 to λN are obtained.

  The memory 11 stores optimum weights when only signals from the desired (master station transmitting station) direction are received. The optimum weight may be stored, for example, when a relay station transmitter is installed and only a reception signal from the master station transmitting station is received in a state where there is no interference wave.

  Subsequently, the comparison unit 12 compares the N eigenvectors wi (i = 1 to N), which are the outputs of the eigenvalue decomposition unit 4, with the optimum weight wopt stored in the memory 11. The comparison unit 12 is a norm between the N eigenvectors wi that are the outputs from the eigenvalue decomposition unit 4 and the optimum weight wopt.

And the eigenvector having the smallest norm is output to the weight generation unit 5 as a weight.

  The weight generation unit 5 generates a synthesis weight for the beam synthesis unit 6 from the eigenvector when the norm is minimized. In this way, the digital baseband signals from the analog-digital conversion devices 3-1 to 3 -N are weighted and combined based on the combined weight generated by the weight generating unit 5 in the beam combining unit 6. The synthesized signal is converted into an OFDM signal through the digital-analog converter 8 and the up-converter 9 and is radiated from the transmitting antenna 10.

  As described above, according to the third embodiment, eigenvalue decomposition is performed on the received signals of the receiving antennas 1-1 to 1-N, and the eigenvectors based on the eigenvalues and the master station recorded in the memory 11 are recorded. A composite weight is generated based on the eigenvector that is most similar to the eigenvector corresponding to the broadcast wave from the master station by comparing with the eigenvector when only the signal from the transmitting station is received. The baseband signal is synthesized by weighting.

  Therefore, since it is possible to extract only the optimum signal among the received signals that have deteriorated due to interference waves or accidental multipaths, the situation is a poor environment in which accidental multipaths or interference waves appear. In addition, it is possible to provide an OFDM broadcast receiving apparatus and an OFDM broadcast relay apparatus that can realize stable relay broadcast.

(Fourth embodiment)
FIG. 4 is a block diagram showing a schematic configuration of an OFDM broadcast relay apparatus according to the fourth embodiment of the present invention. In FIG. 4, the same parts as those in FIG. 3 are denoted by the same reference numerals, and redundant description is omitted here.

  The difference between the relay apparatus in FIG. 4 and the relay apparatus in FIG. 3 is that, in the relay apparatus in FIG. 4, beam combining units 6-1 to 6-m (m is a natural number equal to or less than N) and beam combining units 6-1 to 6-1. A diversity combining unit 7 for combining the signals from 6-m with diversity is provided.

  In the relay apparatus in FIG. 4, the eigenvalue decomposition unit 4 performs eigenvalue decomposition on a part of the OFDM signal that has passed through the analog-digital conversion apparatuses 3-1 to 3 -N and has become a digital baseband signal. The eigenvalue decomposition unit 4 obtains a correlation matrix of received signal vectors having N received signals that are outputs of the analog-digital conversion devices 3-1 to 3-N as vectors, and obtains N eigenvalues λ1 to λN and N Eigenvectors corresponding to the eigenvalues λ1 to λN are obtained. The memory 11 stores optimum weights when only signals from a desired direction (master station transmitting station) are received.

  Subsequently, the comparison unit 12 compares the N eigenvectors wi (i = 1 to N) as the output of the eigenvalue decomposition unit 4 with the optimum weight wint stored in the memory 11. The comparison unit 12 is a norm between the N eigenvectors wi that are the outputs from the eigenvalue decomposition unit 4 and the optimum weight wint.

M is extracted from the smaller norms of the calculated norms, and it is further determined whether or not the extracted m norms are equal to or less than a set threshold value. When all the m norms are equal to or less than the threshold value, the comparison unit 12 outputs eigenvectors corresponding to the m norms to the weight generation unit 5 as weights. On the other hand, when one of the extracted m norms is equal to or smaller than the threshold value, the comparison unit 12 extracts one from the smaller norms shown in the equation (2), and calculates an eigenvector corresponding to the norm. It outputs to the weight generation part 5 as a weight. Then, the (m−1) eigenvectors whose norm exceeds the threshold are output to the weight generation unit 5 with their weights as zero vectors.

  The weight generation unit 5 generates combined weights for the beam combining units 61 to 6m from the weights output from the comparison unit 12, and outputs the combined weights to the beam combining units 6-1 to 6-m. In the beam combiners 6-1 to 6-m, the digital baseband signals are weighted and combined based on the generated combined weight. When a zero vector is output to the weight generation unit 5, the combined weight is generated as zero, and no signal is output from the beam combining unit weighted by the combined weight.

  The signals combined by the beam combining units 6-1 to 6 -m are combined by the diversity combining unit 7, and are transmitted by the transmitting antenna 10 through the digital-analog converter 8 and the up converter 9.

  As described above, according to the fourth embodiment, eigenvalue decomposition is performed on the received signal of each antenna, and only the eigenvector corresponding to the eigenvalue and the signal from the master station transmitting station recorded in the memory 11 are received. Compared with the eigenvectors at the time, a composite weight is generated from a plurality of eigenvectors similar to the signal from the master station, and the digital baseband signal is weighted and synthesized based on the composite weight, and the output Diversity synthesis.

  Therefore, since it is possible to extract only the optimum signal among the received signals that have deteriorated due to interference waves or accidental multipaths, the situation is a poor environment in which accidental multipaths or interference waves appear. In addition, it is possible to provide an OFDM broadcast receiving apparatus and an OFDM broadcast relay apparatus that can realize stable relay broadcast.

  Further, unlike the OFDM broadcast relay apparatus according to the third embodiment of the present invention, since not only the optimal eigenvalue vector but also a plurality of vector signals are combined, the C / N can be further improved.

(Fifth embodiment)
FIG. 5 is a block diagram showing a schematic configuration of an OFDM broadcast relay apparatus according to the fifth embodiment of the present invention. In FIG. 5, the same parts as those in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted here.

  In the relay apparatus in FIG. 5, digital baseband signals output from the analog-digital conversion apparatuses 3-1 to 3-N are transmitted to the beam combining units 6-1 to 6-N. The eigenvalue decomposition unit 4 calculates eigenvalues and eigenvectors corresponding to the eigenvalues based on the outputs of the analog-digital conversion devices 3-1 to 3 -N, and the result is sent to the weight generation unit 5 and the comparison unit 12. Is output. The weight generation unit 5 generates combined weights for the beam combining units 6-1 to 6-N from the input eigenvectors and outputs the combined weights to the beam combining units 6-1 to 6-N.

  On the other hand, the comparison unit 12 compares the input eigenvector with the weight stored in the memory 11, and based on the result, the first system disconnection switch that disconnects the outputs of the beam combining units 6-1 to 6-N. The second system disconnection switch 14 that disconnects the outputs of the 13-1 to 13-N and the diversity combining unit 7 is controlled. The signals combined by the beam combiners 6-1 to 6-N and passed through the first system disconnection switches 13-1 to 13-N are diversity combined by the diversity combiner 7 and pass through the second system disconnect switch 14. And output to the digital-analog converter 8. Thereafter, the signal is transmitted by the transmitting antenna 10 through the up-converter 9.

  The above configuration will be described more specifically.

  A part of the OFDM signal that has passed through the analog-to-digital conversion devices 3-1 to 3-N and has become a digital baseband signal is subjected to eigenvalue decomposition by the eigenvalue decomposition unit 4. The eigenvalue decomposition unit 4 obtains a correlation matrix of received signal vectors having N received signals that are outputs of the analog-digital conversion devices 3-1 to 3-N as vectors, and obtains N eigenvalues λ1 to λN and N Eigenvectors corresponding to the eigenvalues λ1 to λN are obtained. The eigenvector calculated here is output to the weight generation unit 5 and the comparison unit 12.

  The weight generation unit 5 generates a synthesis weight for the beam synthesis units 6-1 to 6-N from the calculated eigenvector.

  On the other hand, the comparison unit 12 compares the N eigenvectors wi (i = 1 to N) that are the outputs of the eigenvalue decomposition unit 4 with the optimum weight wint stored in the memory 11. At this time, the reception weight when only the interference signal is received is stored in the memory 11, and there is no broadcast wave from the master station transmitting station in a state where, for example, the relay station transmitting / receiving apparatus is installed. What is necessary is just to memorize | store the weight when receiving in a state.

  In the comparison unit 12, the norm of the N eigenvectors wi that are the outputs from the eigenvalue decomposition unit 4 and the optimum weight wint

Is calculated, and it is determined whether or not the norm exceeds a set threshold value. If all norms are equal to or less than the threshold value, the comparison unit 12 transmits a control signal to the first system disconnection switches 13-1 to 13-N so as to be turned on (that is, connected). Conversely, when the norm of the eigenvector corresponding to a certain eigenvalue exceeds the threshold, the first system disconnection switches 13-1 to 13-N are configured to disconnect the output of the beam combining unit based on the eigenvector corresponding to the eigenvalue. Send a control signal.

  Furthermore, a second system disconnection switch 14 is connected to the comparison unit 12. When the norm of the eigenvector corresponding to the maximum eigenvalue and the optimal weight exceeds the threshold in the calculation result of the norm of the N eigenvectors wi and the optimal weight wint, the comparison unit 12 outputs the diversity unit 7. A control signal is sent to the second system disconnection switch 14 so as to disconnect.

  As described above, according to the fifth embodiment, eigenvalue decomposition is performed on the received signal of each receiving antenna, and a composite weight is generated from the calculated eigenvalue and the eigenvector corresponding to the eigenvalue. When the calculated eigenvector does not satisfy a predetermined condition by comparing the calculated eigenvector with the eigenvector recorded in the memory 11 when there is no signal from the desired master station transmitting station, The output from the beam combining unit is disconnected by the system disconnection switches 13-1 to 13 -N, or the output of the diversity combining unit 7 shell is disconnected by the second system disconnection switch 14.

  Therefore, since a signal component containing a large amount of interference waves can be removed to some extent, the interference wave components are efficiently suppressed even when the sum of the delay wave and the interference wave exceeds the number N of receiving antennas. It becomes possible. In addition, it is possible to avoid the problem of relaying undesired interference waves in a situation where signals from a desired master station transmitting station cannot be sufficiently received.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

1 is a block diagram showing a schematic configuration of an OFDM broadcast relay apparatus according to a first embodiment of the present invention. The block diagram which shows schematic structure of the OFDM broadcast relay apparatus which concerns on the 2nd Embodiment of this invention. The block diagram which shows schematic structure of the OFDM broadcast relay apparatus which concerns on the 3rd Embodiment of this invention. The block diagram which shows schematic structure of the OFDM broadcast relay apparatus which concerns on the 4th Embodiment of this invention. The block diagram which shows schematic structure of the OFDM broadcast relay apparatus which concerns on the 5th Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... OFDM broadcast receiver, 1-1 to 1-N ... Reception antenna, 2-1 to 2-N ... Down converter, 3-1 to 3-N ... Analog-to-digital converter, 4 ... Eigenvalue decomposition part, 5 ... Weight generating unit 6, 6-1 to 6-N Beam combining unit 7 Diversity combining unit 8 Digital-analog conversion device 9 Up converter 10 Transmitting antenna 11 Memory 12 Comparison , 13-1 to 13-N ... first system disconnection switch, 14 ... second system disconnection switch

Claims (7)

A plurality of receiving units for receiving broadcast signals of an Orthogonal Frequency Division Multiplexing (OFDM) system;
A plurality of analog-to-digital converters that are arranged in a plurality of systems and convert broadcast signals output from the plurality of receivers into digital signals;
An eigenvalue decomposition unit that performs eigenvalue decomposition by inputting a digital signal output from each of the plurality of analog-digital conversion units, and calculates eigenvalues of each of the plurality of systems and eigenvectors corresponding to the eigenvalues;
A combined weight generation unit that generates a combined weight based on the eigenvectors of each of the plurality of systems obtained by the eigenvalue decomposition unit;
A plurality of beam combining units that distribute and supply the digital signals output from each of the plurality of analog-digital conversion units, and weight and combine the digital signals based on the combination weights;
An OFDM broadcast receiving apparatus comprising: a diversity combining unit that performs diversity combining on outputs of the plurality of beam combining units. 2. The OFDM broadcast according to claim 1, wherein the composite weight generation unit generates the composite weight based on eigenvectors corresponding to a predetermined number of eigenvalues from a maximum eigenvalue among eigenvectors obtained by the eigenvalue decomposition unit. Receiver device. further,
Storage means for storing an optimum weight when receiving a broadcast signal from the direction of the master station transmitting station;
2. The OFDM according to claim 1, further comprising: a comparing unit that calculates and compares norms between the eigenvectors of the digital signal and the optimum weights, selects effective eigenvectors, and outputs the selected eigenvectors to the combined weight generation unit. Broadcast receiving device. The comparing means determines whether the norm for a specified number is smaller than a predetermined threshold value from the smaller one of the norms of the digital signals of the plurality of systems and the optimum weight, and determines the effective eigenvector. 4. The OFDM broadcast receiver according to claim 3, wherein the OFDM broadcast receiver is selected. further,
Storage means for storing eigenvectors when signals are received from other than the master station that can be an interference wave, present in the broadcast signal;
Calculating the norm of the eigenvectors of the digital signals of each of the plurality of systems and the eigenvectors stored in the storage means, determining whether the norm is equal to or less than a predetermined threshold and selecting an effective eigenvector, A comparison means for outputting to the composite weight generation unit;
First switching means for cutting off the outputs from the plurality of beam combining units when the norm obtained by the comparison means exceeds the threshold value,
2. The OFDM broadcast receiving apparatus according to claim 1, wherein the diversity combining unit performs diversity combining on the signal passing through the first switch means. further,
Storage means for storing eigenvectors when signals are received from other than the master station that can be an interference wave, present in the broadcast signal;
Calculating the norm of the eigenvectors of the digital signals of each of the plurality of systems and the eigenvectors stored in the storage means, determining whether the norm is equal to or less than a predetermined threshold and selecting an effective eigenvector, A comparison means for outputting to the composite weight generation unit;
The second switch means for cutting off the output from the diversity combining section when the norm when taking the maximum eigenvalue obtained by the comparison means exceeds the threshold value. OFDM broadcast receiver. An OFDM broadcast receiver according to any one of claims 1 to 6, comprising:
An OFDM broadcast relay apparatus, further comprising: a transmission apparatus that retransmits a broadcast signal output from the diversity combining unit.

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