JP2006067338A - Diversity relaying apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diversity relaying apparatus capable of obtaining an excellent relay signal by reducing production of a frequency error due to relaying while enhancing the signal quality by diversity synthesis. <P>SOLUTION: The diversity relaying apparatus is provided with: a frequency error composite section 115 that composes frequency errors of antenna branches respectively shifted by automatic frequency control sections AFC-1 to AFC-N of the antenna branches to obtain a composite frequency error; and a frequency shift section 130 that shifts a frequency of a signal after diversity synthesis by the composite frequency error. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention receives a radio signal transmitted by a digital radio transmission system including an OFDM (Orthogonal Frequency Division Multiplexing) system, etc., by a plurality of antennas, and transmits this as a relay signal after performing diversity combining processing. The present invention relates to a diversity relay device.

  Conventionally, an analog television broadcast wave relay apparatus generally converts a received signal into a baseband signal by frequency-converting the signal, improves signal quality by filtering the baseband signal, and thereafter performs signal power. Is transmitted as a relay signal. By providing such a relay device in multiple stages, a broadcast signal can reach a remote receiving end.

  In addition, there is a diversity relay device that transmits a broadcast signal with higher quality by receiving a broadcast signal with diversity. Among the diversity repeaters, an analog diversity repeater is simply a process of combining or selecting signals from a plurality of antennas in the time domain, so that the frequency accuracy of the local oscillator for frequency conversion is improved. By increasing the frequency, it was possible to reduce the frequency error due to relaying and to achieve performance that could withstand multi-stage relaying.

  On the other hand, in the case of a broadcast wave repeater for digital terrestrial television using the OFDM method, a method of reducing the multipath effect by combining signals from each branch for each subcarrier after discrete Fourier transform has been proposed. (For example, refer to Patent Document 1). This uses the feature of OFDM that inter-symbol interference does not occur if the multipath delay time is within the guard interval. By combining the signals of multiple antenna branches for each subcarrier, The carrier power to noise ratio (C / N) can be effectively improved.

  However, the influence of the frequency error of the local oscillator that down-converts from the radio frequency band to the intermediate frequency band or the base band is not sufficiently considered.

  In general, when an OFDM signal having a frequency error is subjected to a discrete Fourier transform, inter-carrier interference occurs and the demodulation performance is greatly degraded. Therefore, automatic frequency control that compensates for the frequency error is necessary.

  If the signal after discrete Fourier transform is synthesized after automatic frequency control, then inverse discrete Fourier transform is performed, and if it is up-converted again to the intermediate frequency band or radio frequency band, there is an error from the frequency that should be output due to the effect of automatic frequency control. Will occur.

  On the other hand, in the case of digital television broadcasting using the OFDM system, it has been studied to construct a television broadcasting network with a single frequency called SFN (Single Frequency Network). In order to realize this SFN at a low cost, construction of a broadcast wave relay SFN that receives a broadcast wave signal at a relay station and relays it at the same frequency as the reception frequency is being sought. In this case, since the transmission signal at the relay station goes around to the receiving antenna, it is known that not only the quality of the relay signal is deteriorated but also the oscillation occurs in the worst case, leading to the failure of the apparatus. A wraparound canceller technique for avoiding this problem has been proposed (see, for example, Patent Document 2).

  Some wraparound cancellers may cause frequency errors due to their configuration. As described above, a technique has been proposed in which a frequency error is canceled after the canceller (see, for example, Patent Document 3). In the SFN broadcast wave relay network to which the wraparound canceller is applied, if there is a frequency error between the received signal and the transmitted signal at the relay station, the broadcast wave from the master station and the relay broadcast wave from the relay station (relay device) At the receiving terminal where both signals arrive, the reception quality is significantly degraded due to the frequency error. This is because the signals cannot be regarded as simple delayed waves and interfere with each other. Therefore, a configuration for preventing a frequency error is essential.

  On the other hand, when relaying using a plurality of frequencies as in MFN (Multi Frequency Network), the influence of this frequency error is less than in the case of SFN. In the case of MFN, since the frequency channel of each signal is different for the receiving terminal to which both the broadcast wave from the master station and the relay broadcast wave from the relay station arrive, these signals are easily selected by a filter or the like. Because it is possible.

  However, when multi-stage relay is implemented in MFN, even if the frequency error at each relay station is small, the frequency error is accumulated by the multi-stage relay, and the signal transmitted from the last-stage relay station exceeds the reception error of the receiving terminal. May be included. For this reason, it is necessary to take measures to prevent frequency errors from occurring at each relay station.

  That is, this frequency error does not occur even in an MFN diversity relay device that receives signals from a plurality of antennas and combines (including equalization) each signal and relays the received signal on a frequency channel different from that of the received signal. It is necessary to do so.

By the way, in the reception environment of a relay station where there is a delayed wave, simply by synthesizing the signal in the time axis domain without performing automatic frequency control on the baseband signal like an analog diversity relay device. It is difficult to improve relay quality.
JP 2002-271291 A Japanese Patent Laid-Open No. 2002-152065 JP 2001-285167 A

  As described above, in a digital radio signal relay apparatus, reducing a frequency error between a reception signal and a transmission signal is very important for supplying a good quality broadcast signal to the reception end.

  However, in the conventional configuration, consideration is given to reducing the frequency error in the wraparound cancel device provided in the relay device that relays the signal received by the single antenna at the same frequency as the reception frequency channel. However, sufficient consideration has not been given to reducing the frequency error in the diversity repeater that diversity-combines signals received by multiple antennas and transmits them as a relay signal, which degrades the signal quality at the receiving end. There was a fear.

  The present invention has been made in view of the above points, and provides a diversity relay device capable of obtaining a good relay signal by reducing the occurrence of frequency error due to relay while improving signal quality by diversity combining. Objective.

  In order to solve this problem, the present invention provides a frequency synthesizing unit that synthesizes a frequency error shifted by an automatic frequency control process in each antenna branch, and a frequency shift unit that shifts the frequency of a diversity synthesized signal by the synthesized frequency error. And so on. As a result, the frequency shift amount of the signal after diversity combining can be accurately returned to the original signal so as to match the frequency characteristics, so that the frequency error caused by the relay can be reduced.

  ADVANTAGE OF THE INVENTION According to this invention, the diversity relay apparatus which can reduce the generation | occurrence | production of the frequency error by relay and can obtain a favorable relay signal can be implement | achieved, improving signal quality by diversity combining.

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

  FIG. 1 shows a configuration of a diversity relay apparatus according to an embodiment of the present invention. Diversity relay apparatus 100 includes N reception antennas 101-1 to 101-N, N reception conversion units 102-1 to 102-N, and N analog / digital conversion units (A / D) 103-. 1 to 103-N, N orthogonal demodulation units 104-1 to 104-N, N automatic frequency control units AFC-1 to AFC-N, and N fast Fourier transform units (FFT) 108- 1 to 108-N, N propagation path estimation units 109-1 to 109-N, a synthesis unit 110, a determination unit 111, an inverse fast Fourier transform unit (IFFT) 112, a frequency shift unit 130, The frequency error synthesis unit 115, the quadrature modulation unit 116, the digital / analog conversion unit (D / A) 117, the transmission conversion unit 118, the synchronization signal generation unit 119, and the transmission antenna 120 are included.

  That is, diversity relay apparatus 100 includes branch processing units BR-1 to BR-N that independently receive and process signals of N reception antennas 101-1 to 101-N. This is the same configuration as that of a general OFDM receiver that performs diversity reception. In the following description, in order to simplify the description, when similar processing is performed in each element of each branch processing unit BR-1 to BR-N, for example, the reception conversion units 102-1 to 102-N are indicated. May be simply referred to as the reception conversion unit 102.

  The reception conversion unit 102 converts the frequency of the radio frequency signal to an intermediate frequency band (IF band). Here, the reception conversion unit 102 performs frequency conversion using a sine wave synchronized with the input synchronization signal. In practice, each of the reception conversion units 102-1 to 102-N mixes the output from each of the antennas 101-1 to 101-N using sine waves generated by the same frequency generation source. The outputs of the antennas 101-1 to 101-N are down-converted to the IF band. In addition to the frequency conversion process, the reception conversion unit 102 performs other reception processes such as amplification.

  The output signal of the reception conversion unit 102 is subjected to analog / digital conversion by the analog / digital conversion unit 103 and then orthogonally demodulated by the orthogonal demodulation unit 104 to be a complex signal.

  Next, the diversity relay apparatus 100 performs automatic frequency control on each branch independently by the automatic frequency control units AFC-1 to AFC-N with respect to the signal after quadrature demodulation. Specifically, the frequency error detection unit 107 detects a frequency error based on the output of the complex multiplication unit 105, the complex sine wave generation unit 106 generates a complex sine wave that compensates the frequency error, and the complex multiplication unit 105 By multiplying the quadrature demodulated signal by a complex sine wave, the automatic frequency control units AFC-1 to AFC-N can obtain a baseband signal with a small frequency error. In this way, automatic frequency control is performed independently at each branch.

  The signal subjected to the automatic frequency control is input to the FFT 108. Of course, before the input to the FFT 108, the guard interval is removed by a guard interval removing unit (not shown), and an effective symbol length signal is input to the FFT 108. An output signal from the FFT 108 is sent to the propagation path estimation unit 109 and the synthesis unit 110.

  The propagation path estimation unit 109 estimates the frequency characteristics of the entire signal band (that is, all subcarriers) based on the pilot carrier, and sends the estimated propagation path characteristics to the synthesis unit 110. The synthesizing unit 110 as a branch signal synthesizing unit weights the signal of each subcarrier output from the FFT 108 with the channel estimation value of each subcarrier obtained by the corresponding channel estimating unit 109, and further from each branch. The baseband signals obtained by the respective branch processing units BR-1 to BR-N are synthesized so as to be added for each subcarrier.

  As a combining method, for each subcarrier, selective combining for equalizing and outputting the branch with the best propagation path estimated value, or the maximum ratio weighted based on the quality of the propagation path estimated value of each branch and combining Synthesis and the like are conceivable, but the present invention is not limited to these synthesis methods.

  The output of the synthesis unit 110 is sent to the determination unit 111. The determination unit 111 determines the synthesis result according to the modulation method, and sends the determination result to the inverse fast Fourier transform unit (IFFT) 112. Note that the determination unit 111 may be connected to bypass the main processing system. The output of IFFT 112 is output to complex multiplication section 113 of frequency shift section 130.

  The complex multiplier 113 multiplies the output of the IFFT 112 by the complex sine wave generated by the complex sine wave generator 114, thereby compensating the frequency error compensated for the output of the IFFT 112 by the reception side (that is, the complex multiplier 105). Is added again. The complex sine wave generating unit 114 generates a complex sine wave based on the combined frequency error obtained by the frequency error combining unit 115.

  Here, the frequency error synthesis unit 115 receives the frequency error signals S1 to SN detected by the frequency error detection units 107-1 to 107-N of the branch processing units BR-1 to BR-N, and receives the frequency error signal S1. The synthesized frequency error is obtained by synthesizing ~ SN. As a result, the frequency shift unit 130 shifts the frequency of the signal after diversity combining by a value obtained by combining the frequency errors of the respective antenna branches and cancels the frequency error caused by the automatic frequency control. There is no error.

  The OFDM signal returned to the frequency before the automatic frequency control by the frequency shift unit 130 is orthogonally modulated by the orthogonal modulation unit 116 and then converted into an analog signal by the digital / analog conversion unit (D / A) 117. The output of the digital / analog converter (D / A) 117 is converted into a desired frequency channel by the transmission converter 118 and amplified, and then radiated into the air from the transmission antenna 120.

  Here, the transmission conversion unit 118 generates a sine wave based on the synchronization signal input from the synchronization signal generation unit 119, and multiplies the output of the digital / analog conversion unit (D / A) 117 by a desired sine wave. The frequency channel signal is obtained. The synchronization signal generated by the synchronization signal generation unit 119 is also sent to the reception conversion unit 102. Thus, in diversity relay apparatus 100, by making the synchronization signal used in transmission conversion section 118 the same as the synchronization signal used in reception conversion section 102, the frequency error at the reception end and transmission end can be further reduced. Has been made. Note that it is preferable that the synchronization signal generation unit 119 is highly accurate so as not to cause an error even with respect to environmental fluctuation factors such as temperature.

  An example of the configuration of the frequency error synthesizer 115 is shown in FIG. In FIG. 2, the frequency error synthesizer 115 weights the frequency error values S1 to SN of each branch by weighting units 201-1 to 201-N and weighting units 201-1 to 201-N. A weighting control unit 202 for controlling and an addition unit 203 for obtaining a sum of weighted frequency errors are included.

  In addition to the frequency error values S1 to SN from each branch, the frequency error synthesizer 115 receives a signal indicating the signal quality of each branch. Specifically, a signal indicating the signal quality of each branch is input to the weighting control unit 202, and the frequency error values S1 to SN from each branch are input to the weighting units 201-1 to 201-N. In practice, the frequency error synthesizer 115 weights the frequency error of the branch with better signal quality. The synthesized frequency error obtained by the adder 203 is sent to the complex sine wave generator 114.

  As a signal indicating the signal quality of each branch, for example, as shown in FIG. 3, for example, an automatic gain control unit (AGC) 302-1 provided in each of the reception conversion units 102-1 to 102-N in each branch is generally used. A control voltage can be used. The configuration of FIG. 3 will be briefly described. A reception signal received by the antenna 101-1 is amplified by a low noise amplification unit (LNA) 301-1, and an analog / digital conversion unit (A / D) 103-1 by an automatic gain amplification unit (AGC) 302-1. After the signal is set to a constant level suitable for the input level, the signal is input to the multiplier 303-1. Multiplier 303-1 multiplies the sine wave generated by sine wave generator 304-1 and the AGC output to downconvert the AGC output. The down-converted signal is sent to the analog / digital conversion unit 103-1 via the band pass filter 305-1.

  Here, the control voltage of AGC generally becomes larger as the input signal level is smaller, that is, the received signal quality is worse. That is, the quality of the received signal can be estimated based on the control voltage. As a result, the weighting control unit 202 inputs the control voltage of the AGC of each branch as information indicating the signal quality of each branch, so that it is proportional to the magnitude of the signal power input to each branch. The frequency error value can be weighted and synthesized. Since such an AGC circuit is generally provided in a diversity relay apparatus in order to make the signal level of each antenna branch signal before analog / digital conversion constant, it is necessary to add a circuit for obtaining signal quality separately. Disappear. As a result, the frequency error of each antenna can be synthesized based on the signal quality with a simple configuration.

  Further, a signal-to-noise ratio (S / N) may be used as a signal indicating the signal quality of each branch. This S / N can be obtained by, for example, a configuration as shown in FIG. The configuration of FIG. 4 will be briefly described. The S / N estimation unit 401-1 receives the FFT output signal Dn (k) (n: branch number, k: subcarrier number) and the output Hn (k) of the propagation path estimation unit 109-1. The S / N estimation unit 401-1 first compensates the distortion component of the output signal Dn (k) of the FFT based on the output Hn (k) of the propagation path estimation unit 109-1, and the ideal signal point in the compensated signal. The S / N estimated value Qn (n: branch number) is obtained by accumulating the sum of noise components.

のように、伝搬路特性Ｈｎ（ｋ）でＦＦＴ出力信号Ｄｎ（ｋ）を除することで歪成分を補償し、補償後の信号の雑音成分を求め、これを伝搬路特性Ｈｎ（ｋ）の電力で重み付けしたものをすべてのサブキャリア（Ｎｄ個）にわたって累積する。ここで、伝搬路特性Ｈｎ（ｋ）の電力による重み付けは省略可能ではあるが、推定精度は劣化してしまう。さらに、回路規模削減のためにＨｎ（ｋ）の電力の代わりに、Ｈｎ（ｋ）の複素振幅の絶対値和とすることも可能ではある。また累積数としては、すべてのサブキャリア（Ｎｃ個）としなくとも、十分な精度が得られる個数に限定することも好適である。累積個数を限定する場合には、伝搬路推定部１０９への入力信号である、ＦＦＴ出力信号Ｄｎ（ｋ）や伝搬路特性Ｈｎ（ｋ）も同様に限定することが可能であり、好適である。 That is, the S / N estimation unit 401-1

As shown, the distortion component is compensated by dividing the FFT output signal Dn (k) by the propagation path characteristic Hn (k), the noise component of the compensated signal is obtained, and this is obtained as the propagation path characteristic Hn (k). The power weighted one is accumulated over all subcarriers (Nd). Here, the weighting of the propagation path characteristic Hn (k) by the power can be omitted, but the estimation accuracy deteriorates. Further, in order to reduce the circuit scale, the absolute value sum of the complex amplitudes of Hn (k) can be used instead of the power of Hn (k). Further, it is also preferable that the cumulative number is limited to the number that can obtain sufficient accuracy even if not all the subcarriers (Nc). When limiting the cumulative number, it is possible to limit the FFT output signal Dn (k) and the propagation path characteristic Hn (k), which are input signals to the propagation path estimation unit 109, as well. .

のように、伝搬路特性の合計電力を乗じておくと、ＡＧＣ出力においてブランチ間のレベルが異なる場合にも適切な信号品質を得ることができ一段と好適である。 Where:

As described above, when the total power of the propagation path characteristics is multiplied, an appropriate signal quality can be obtained even when the levels between the branches are different in the AGC output, which is more preferable.

  In this way, unlike weighting that is proportional to the magnitude of signal power, a more accurate system that is less susceptible to interference is constructed by using an indicator that indicates the signal quality itself, which is the signal-to-noise ratio. This is preferable.

  Next, the operation of diversity relay apparatus 100 of the present embodiment will be described.

  Diversity repeater 100 independently detects a frequency error for each branch signal, which is a complex baseband signal, and performs automatic frequency control so that this frequency error is eliminated. That is, since each branch signal has a frequency error unique to each branch due to a difference in propagation path, individual differences in circuits, and the like, the automatic gain control units AFC-1 to AFC-N have their own unique frequency errors. Frequency error is suppressed independently for each branch.

  The signal of each branch in which the frequency error is canceled is synthesized by the synthesis unit 110 as a branch signal synthesis unit. At this time, since the synthesizing unit 110 synthesizes the signal in which the frequency error has been canceled, it is possible to perform a satisfactory synthesis process.

  Diversity relay apparatus 100 restores the frequency of the combined signal by the amount shifted by automatic frequency control, so that no frequency shift due to relay occurs.

  At this time, in diversity relay apparatus 100 of the present embodiment, frequency error combining section 115 combines the frequency errors detected by automatic frequency control sections AFC-1 to AFC-N of each branch, thereby combining frequency errors. The frequency shift unit 130 shifts the frequency of the signal after diversity combining by this combined frequency error. As a result, the frequency characteristics during reception can be maintained satisfactorily. As a result, it is possible to effectively improve the signal quality by diversity combining while maintaining the frequency characteristics at the time of reception.

  Thus, according to the present embodiment, the frequency error synthesizer 115 obtains a synthesized frequency error by synthesizing the frequency error of each antenna branch shifted by each of the automatic frequency controllers AFC-1 to AFC-N of each antenna branch. And a frequency shift unit 130 that shifts the frequency of the diversity combined signal by the combined frequency error, the signal quality can be effectively improved by diversity combining while maintaining the frequency characteristics at the time of reception. Diversity relay device 100 can be realized.

  In the above-described embodiment, the case where the frequency error synthesizer 115 is configured as shown in FIG. 2 has been described. However, the configuration of the frequency error synthesizer 115 is not limited to this, for example, FIG. 5, FIG. It may be configured as shown in FIG.

  The frequency error synthesis unit 115 shown in FIG. 5 selects a selection unit 501 that selects the frequency error values S1 to SN of each branch, and a selection control unit 502 that determines which frequency error values S1 to SN are selected and output by the selection unit 501. And have. The selection control unit 502 controls the selection unit 501 to output the frequency error value of the branch with the best signal quality based on the signal indicating the signal quality of each branch as described above. Thereby, the frequency shift unit 130 shifts the frequency of the diversity combined signal based on the frequency error controlled by the automatic frequency control unit AFC of one branch having the highest signal quality. According to the configuration of FIG. 5, the circuit configuration can be further simplified as compared with the configuration of FIG. 2. The configuration of FIG. 2 is more suitable when the combining unit 110 performs diversity combining by increasing the weight of a branch signal having better signal quality, and the configuration of FIG. 5 is the signal of the branch having the best signal quality by the combining unit 110. It is more preferable to select and synthesize diversity.

  The frequency error synthesizer 115 shown in FIG. 6 is provided with a low-pass filter (LPF) 601 in the subsequent stage of the selector 501 compared to the configuration of FIG. Thereby, a sudden change in the output frequency error value can be suppressed at the time of selection switching. As a result, an unstable transient state can be avoided even when the selection unit 501 frequently switches.

  The frequency error synthesizer 115 shown in FIG. 7 forms a synthesized frequency error by averaging only the frequency errors of the antenna branches receiving a desired signal among a plurality of antenna branches. . That is, the frequency error values S1 to SN of each branch are averaged, but the frequency error values of the branches where a desired signal is not obtained are not included in the averaging. As an example of criteria for determining whether a signal is a desired signal, synchronization for checking whether a synchronization signal included in a TMCC (Transmission and Multiplexing Configuration Control) signal used in terrestrial digital broadcasting has a desired bit pattern The determination result of the establishment determination unit (not shown) can be used. The synchronization establishment determination unit receives, as inputs, the output signals from the FFTs 108-1 to 108-N provided in the respective branches in FIG. 1, and decodes the subcarriers to which the TMCC signal is assigned. It is checked whether or not the synchronization signal is included.

  Thus, if only the frequency error values of the branches from which the desired signal is obtained are averaged, stable frequency error synthesis can be performed with a small circuit scale.

  7 inputs error signals S1 to SN from the respective branches BR-1 to BR-N to switching units (SW) 701-1 to 701-N, and switches 701-1 to 701. The synchronization establishment determination signal from the synchronization establishment determination unit described above is input to −N as a switching control signal. As a result, among the error signals S1 to SN from the respective branches BR-1 to BR-N, only the branch in which synchronization is established is input to the adding unit 703 of the averaging unit 705. The synchronization establishment branch counting unit 702 counts the number of branches that have established synchronization, and sends the number M of branches that have established synchronization to the multiplication unit 704 of the averaging unit 705. The multiplication unit 704 multiplies the addition result of the addition unit 703 by 1 / M. Thereby, it is possible to selectively average only the frequency error of the branch in which synchronization is established.

  The present invention also relates to either a diversity relay apparatus that transmits a diversity combined signal as a relay signal having a frequency different from that of the reception frequency channel, or a diversity relay apparatus that transmits the diversity combined signal as a relay signal having the same frequency as the reception frequency channel. It can also be applied to. Incidentally, when making the reception frequency and the transmission frequency different, the frequency of the sine wave used for the up-conversion in the transmission conversion unit 118 is made different from the frequency of the sine wave used for the down-conversion in the reception conversion unit 102. Conversely, when the reception frequency and the transmission frequency are the same, the frequency of the sine wave used for up-conversion in the transmission conversion unit 118 is the same as the frequency of the sine wave used for down-conversion in the reception conversion unit 102. do it.

  Furthermore, although the case where the diversity relay apparatus of the present invention is configured as shown in FIG. 1 has been described in the embodiment, it may be configured as shown in FIG. 8, for example. The diversity relay apparatus 800 of FIG. 8 includes a plurality of antennas 101-1 to 101-N and frequency errors S1 to S1 in the antenna branches BR-1 to BR-N provided in the antenna branches BR-1 to BR-N, respectively. A plurality of frequency error detectors 107-1 to 107-N that independently detect SN in each antenna branch BR-1 to BR-N and frequency errors S1 to SN in each antenna branch BR-1 to BR-N are combined. Thus, a frequency error synthesizer 115 for obtaining a synthesized frequency error and a plurality of first frequency shifters commonly provided for each antenna branch BR-1 to BR-N to shift the frequency of all branch signals in common so as to compensate for the synthesized frequency error. 1 frequency shift units (complex multipliers) 105-1 to 105-N and frequency-shifted antenna branches BR-1 to BR- Branch signal synthesizer (synthesizing unit) 110 for diversity-combining the above signals, and the signals after diversity combining are shifted to the opposite side by the frequency shift by the first frequency shift units (complex multipliers) 105-1 to 105-N. And a second frequency shift unit 801 for shifting.

  Here, the second frequency shift unit 801 has a complex sine wave generation unit 114 that generates a complex sine wave corresponding to the combined frequency error, a sign inversion unit 802 that inverts the sign of the generated complex sine wave, and a sign inverted. And a complex multiplier 113 that multiplies the signal after IFFT by the complex sine wave. Then, the common complex sine wave generated by the complex sine wave generation unit 114 is sent to the first frequency shift units (complex multiplication units) 105-1 to 105-N.

  A feature of diversity relay apparatus 800 is that frequency error components from the respective branches are synthesized and a complex sine wave common to all branches is multiplied. In other words, the received signal received by each antenna will have different frequency errors due to differences in propagation path, individual differences in circuits of each antenna branch, etc., but if the difference in frequency error between branches is very small The complex sine wave generator 114 is assumed to be shared. Thereby, the circuit scale can be reduced by the amount that the complex sine wave generator 114 can be shared.

  The present invention is not limited to the embodiment described above, and can be implemented with various modifications.

  In one aspect of the diversity relay apparatus of the present invention, a diversity relay apparatus that receives a diversity signal by a plurality of antennas and transmits the diversity reception signal as a relay signal, the plurality of antennas being connected to each antenna branch. A plurality of automatic frequency control means provided independently for controlling frequency errors in each antenna branch independently at each antenna branch, a branch signal combining means for diversity combining the signals of each antenna branch controlled automatically, and a plurality of automatic A frequency error synthesizing unit that obtains a synthesized frequency error by synthesizing the frequency error of each antenna branch shifted by each frequency control unit; and a frequency shift unit that shifts the frequency of the signal after diversity synthesis by the synthesized frequency error. The structure which comprises is taken.

  According to this configuration, the received signals received by the respective antennas have different frequency errors due to differences in propagation paths, individual differences in the circuits of the respective antenna branches, and the like. Different frequency errors for each branch are suppressed. As a result, the branch signal synthesizing unit synthesizes the branch signal in which the frequency error is suppressed by the automatic frequency control unit, so that it is possible to perform an excellent diversity synthesis process. The frequency-shifted means shifts the frequency of the diversity combined signal so that the frequency shifted by the automatic frequency control means is returned again. At this time, since the frequency shift means shifts the frequency of the signal after diversity combining by the combined frequency error obtained by combining the frequency errors of the respective antenna branches, the frequency error caused by the automatic frequency control can be canceled and transmitted. Frequency error does not occur in the generated signal. As a result, it is possible to effectively improve the signal quality by diversity combining while maintaining the frequency characteristics at the time of reception.

  In one aspect of the diversity relay apparatus of the present invention, a diversity relay apparatus that receives a diversity signal by a plurality of antennas and transmits the diversity reception signal as a relay signal, the plurality of antennas being connected to each antenna branch. A plurality of frequency error detecting means provided independently for detecting frequency errors in each antenna branch, frequency error synthesizing means for obtaining a combined frequency error by synthesizing frequency errors in each antenna branch, and each antenna A plurality of first frequency shift means for frequency-shifting each branch signal at a common frequency so as to compensate for a combined frequency error provided in each branch, and branch signal synthesis means for diversity-combining the signals of each antenna branch that has been frequency-shifted And diversity A configuration having a second frequency shifting means for shifting to the opposite side by the amount of frequency shift in the signal after forming the first frequency shifting means.

  According to this configuration, in addition to the above-described effects, the circuit scale can be reduced by the amount that the complex sine wave in the second frequency shift means can be shared.

  In one aspect of the diversity relay apparatus of the present invention, the frequency error synthesis means adopts a configuration in which the frequency error in each antenna branch is weighted and synthesized based on the signal quality in each antenna branch to obtain a synthesized frequency error. .

  According to this configuration, it is possible to perform greater weighting as the frequency error of the antenna branch with better signal quality. Also in diversity combining, generally, a signal having higher signal quality is weighted more or a branch signal having the best signal quality is selected, so that frequency shift processing in accordance with diversity combining processing can be performed. As a result, it is possible to perform more accurate frequency shift processing on the signal after diversity combining.

  In one aspect of the diversity relay apparatus of the present invention, the frequency error synthesis means adopts a configuration in which a frequency error in an antenna branch having the best signal quality among a plurality of antenna branches is selected as a synthesized frequency error.

  According to this configuration, since the frequency error of the antenna branch with the best signal quality is selected, in diversity combining, when the signal with the better signal quality is weighted or when the signal of the branch with the best signal quality is selected. Thus, it becomes possible to perform frequency shift processing in accordance with diversity combining processing. As a result, it is possible to perform more accurate frequency shift processing on the signal after diversity combining.

  In one aspect of the diversity relay apparatus of the present invention, when adopting a configuration in which the frequency error in the antenna branch with the best signal quality is selected as the combined frequency error, the frequency error combining means selects the antenna branch with the highest quality selected. A configuration including a low-pass filter that passes only a low-frequency component of the frequency error in FIG.

  According to this configuration, it is possible to avoid an unstable transient state that occurs when the selected frequency error is frequently switched.

  In one aspect of the diversity relay apparatus of the present invention, a configuration is obtained in which a combined frequency error is obtained by selectively averaging only frequency errors in an antenna branch receiving a desired signal among a plurality of antenna branches. Take.

  According to this configuration, frequency errors in a plurality of antenna branches can be averaged, and stable frequency shift processing can be realized with a simple configuration.

  In one aspect of the diversity relay apparatus of the present invention, the configuration is such that the signal quality in each antenna branch is obtained based on the magnitude of the control voltage of the automatic gain control means for making the signal level of each antenna branch signal constant. take.

  According to this configuration, in order to make the signal level of each antenna branch signal constant, the signal quality of each antenna branch signal is generally obtained based on the control voltage of the automatic gain control means provided in the diversity repeater. Therefore, it becomes possible to synthesize the frequency error of each antenna based on the signal quality with a simple configuration without separately adding a circuit for obtaining the signal quality.

  In one aspect of the diversity relay apparatus of the present invention, propagation path estimation means for estimating the propagation path of each antenna branch reception signal, and distortion components of each antenna reception signal are compensated based on the propagation path estimation result of each antenna branch. S / N estimation means for estimating the signal-to-noise ratio of each antenna branch reception signal based on the distance of the compensated signal point from the ideal signal point, and the estimation result by the S / N estimation means The configuration used as the signal quality in each antenna branch is adopted.

  According to this configuration, the signal quality in each antenna branch can be accurately obtained by the S / N estimation means.

  The diversity relay apparatus according to the present invention can obtain a good relay signal by improving the signal quality by diversity combining, reducing the occurrence of frequency error due to relay, and including a broadcast signal repeater. Widely applicable to repeaters.

The block diagram which shows the structure of the diversity relay apparatus which concerns on one embodiment of this invention Block diagram showing a configuration example of the frequency error synthesizer Block diagram showing a configuration example of the reception conversion unit The block diagram which shows the structural example for calculating | requiring S / N Block diagram showing a configuration example of the frequency error synthesizer Block diagram showing a configuration example of the frequency error synthesizer Block diagram showing a configuration example of the frequency error synthesizer The block diagram which shows another structural example of the diversity relay apparatus of this invention

Explanation of symbols

100, 800 Diversity repeater 101-1 to 101-N Reception antenna 102-1 to 102-N Reception conversion unit 103-1 to 103-N Analog / digital conversion unit (A / D)
104-1 to 104-N Orthogonal demodulation units 105-1 to 105-N, 113 Complex multiplication units 106-1 to 106-N, 114 Complex sine wave generation units 107-1 to 107-N Frequency error detection unit 108-1 ~ 108-N Fast Fourier Transform (FFT)
109-1 to 109 -N Propagation path estimation unit 110 Combining unit 111 Determination unit 112 Inverse fast Fourier transform unit (IFFT)
Reference Signs List 115 Frequency error synthesis unit 116 Quadrature modulation unit 117 Digital / analog conversion unit 118 Transmission conversion unit 119 Synchronization signal generation unit 120 Transmission antenna 130, 801 Frequency shift unit 201-1 to 201-N Weighting unit 202 Weighting control unit 203 Addition unit 301 -1 Low noise amplifier (LNA)
302-1 Automatic gain controller (AGC)
303-1 Multiplier 304-1 Sine wave generator 305-1 Band pass filter 401-1 Signal to noise ratio estimator (S / N estimator)
501 Selection unit 502 Selection control unit 601 Low-pass filter (LPF)
802 Sign inversion unit BR-1 to BR-N Branch processing unit AFC-1 to AFC-N Automatic frequency control unit S1 to SN Frequency error signal

Claims (8)

A diversity relay apparatus that receives a radio signal with a plurality of antennas and transmits the diversity reception signal as a relay signal,
Multiple antennas,
A plurality of automatic frequency control means provided in each antenna branch, each independently controlling the frequency error in each antenna branch;
Branch signal combining means for diversity combining the signals of each antenna branch controlled automatically;
A frequency error synthesizing means for obtaining a synthesized frequency error by synthesizing the frequency error of each antenna branch shifted by each of the plurality of automatic frequency control means;
A diversity relay apparatus comprising: frequency shift means for shifting the frequency of a signal after diversity combining by an amount corresponding to the combined frequency error. A diversity relay apparatus that receives a radio signal with a plurality of antennas and transmits the diversity reception signal as a relay signal,
Multiple antennas,
A plurality of frequency error detection means provided in each antenna branch, each independently detecting a frequency error in each antenna branch;
A frequency error synthesizing means for obtaining a synthesized frequency error by synthesizing the frequency error in each antenna branch;
A plurality of first frequency shift means provided in each antenna branch, respectively, for frequency shifting each branch signal at a common frequency so as to compensate for the combined frequency error;
Branch signal combining means for diversity combining the frequency-shifted signal of each antenna branch;
Diversity relay apparatus comprising: second frequency shift means for shifting the signal after diversity combining to the opposite side as much as frequency shifted by the first frequency shift means. The diversity relay apparatus according to claim 1, wherein the frequency error combining unit obtains the combined frequency error by weighting and combining the frequency error in each antenna branch based on the signal quality in each antenna branch. The diversity relay apparatus according to claim 1, wherein the frequency error combining unit selects a frequency error in an antenna branch having the best signal quality among the plurality of antenna branches as the combined frequency error. The diversity relay apparatus according to claim 4, wherein the frequency error synthesis unit includes a low-pass filter that passes only a low-frequency component of the frequency error in the selected antenna branch having the highest quality. The frequency error synthesizing unit obtains the synthesized frequency error by selectively averaging only the frequency error in an antenna branch receiving a desired signal among the plurality of antenna branches. Item 3. The diversity relay device according to Item 2. The diversity according to any one of claims 3 to 6, wherein the signal quality in each antenna branch is obtained based on the magnitude of the control voltage of the automatic gain control means for making the signal level of each antenna branch signal constant. Relay device. Propagation path estimating means for estimating the propagation path of each antenna branch reception signal, and compensating the distortion component of each antenna reception signal based on the propagation path estimation result of each antenna branch, and the ideal signal point of the signal point after compensation An S / N estimation unit that estimates a signal-to-noise ratio of each antenna branch reception signal based on a distance from the antenna branch, and uses an estimation result obtained by the S / N estimation unit as a signal quality in each antenna branch. The diversity relay device according to claim 3.

Images