JP2006115096A - Multi-carrier communication apparatus and method of suppressing peak power - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the deterioration of receiving quality while the peak power of a multi-carrier signal is suppressing. <P>SOLUTION: A quality information demodulator 111 demodulates quality information for every carrier contained in a received signal. A filter coefficient determination part 112 determines a filter coefficient which passes only the band of the carrier with inferior receiving quality in a communication partner not illustrated. In a filter 107, a filter coefficient determined by the filter coefficient determination part 112 is set, and it is subjected to about the band confinement by filtering to the peak component outputted from a subtractor 106. A subtractor 108 subtracts the peak component after the filtering from the multi-carrier signal, and suppresses the peak power. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a multicarrier communication apparatus and a peak power suppression method, and more particularly, to a multicarrier communication apparatus and a peak power suppression method that perform filtering to suppress peak power.

  In recent years, as a technique for improving communication quality by improving tolerance to frequency selective fading, for example, multicarrier such as OFDM (Orthogonal Frequency Division Multiplexing) method and MC-CDMA (Multi Carrier-Code Division Multiple Access) method Communication methods are attracting attention. In the multicarrier communication system, signals are transmitted using a plurality of carriers having different frequencies. At this time, a plurality of carriers are added and transmitted on the transmission side. The power may protrude only at the part and a peak may occur. When a signal having a peak is input to the nonlinear amplifier, nonlinear distortion occurs in the output signal from the amplifier, causing deterioration of reception characteristics and out-of-band radiation on the reception side.

  Therefore, as a method for suppressing peak power in the multicarrier communication system, processing using clipping or filtering forcibly cutting peak components has been studied. For example, in Patent Document 1, a peak component having power greater than or equal to a threshold value is extracted from a multicarrier signal, and the peak component is subjected to filtering by a low-pass filter, a FIR (Finite Impulse Response) filter, or the like to limit the band. It is disclosed that the peak component after restriction is subtracted from the original multicarrier signal. According to this method, the peak is not reproduced after filtering, and it is not necessary to repeat the processing, so that the processing amount can be reduced.

Further, for example, in Patent Document 2, peak power suppression is performed by suppressing peak power using a plurality of FIR filters, and selecting a signal with good signal quality after peak power suppression among outputs of each FIR filter. It describes reducing signal quality degradation.
JP 2004-104162 A JP 2004-146974 A

  However, the above-described conventional technique has a problem that the demodulation characteristics of the multicarrier signal on the receiving side are not necessarily good because the multicarrier signal after peak power suppression is affected by the propagation path. That is, the characteristics of the propagation path through which the multicarrier signal is transmitted change from moment to moment and are not constant. For this reason, even if peak power is suppressed on the transmission side and reception characteristics on the reception side are improved, reception quality of a multicarrier signal may deteriorate depending on propagation path characteristics.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a multicarrier communication apparatus and a peak power suppression method capable of reducing degradation of reception quality while suppressing peak power of a multicarrier signal. And

  A multicarrier communication apparatus according to the present invention includes a filter that band-limits a peak component included in a multicarrier signal in which data is superimposed on a plurality of carriers, and reception quality at a communication partner of the plurality of carriers is based on a predetermined reference. An acquisition means for acquiring information on a poor carrier that is not satisfied, a determination means for determining a filter coefficient of the filter in accordance with the acquired information on the bad carrier, and a peak after passing through the filter in which the determined filter coefficient is set A configuration having subtracting means for subtracting the component from the multicarrier signal and transmitting means for transmitting the multicarrier signal after the peak component subtraction is adopted.

  A peak power suppression method according to the present invention is a peak power suppression method for suppressing peak power by performing filtering for band-limiting peak components included in a multicarrier signal in which data is superimposed on a plurality of carriers. A step of acquiring information on a bad carrier whose reception quality at a communication partner does not satisfy a predetermined standard, a step of determining a filter coefficient of a filter according to the acquired information on the bad carrier, and the determined filter A step of subtracting the peak component after passing through the filter in which a coefficient is set from the multicarrier signal; and a step of transmitting the multicarrier signal after subtraction of the peak component.

  According to these, the peak component is band-limited by the filter in which the filter coefficient determined according to the bad carrier information is set, and the peak component after the band limitation is subtracted from the multicarrier signal and transmitted, for example, the peak Of the components, only the frequency component corresponding to the inferior carrier can be subtracted from the multicarrier signal, and carriers with good reception quality at the communication partner are not attenuated at all, and the superimposed data is not lost. For this reason, the influence on the reception quality by the peak power suppression using filtering can be suppressed, and the deterioration of the reception quality of the multicarrier signal can be reduced.

  According to the present invention, it is possible to reduce deterioration of reception quality of a multicarrier signal.

  The essence of the present invention is to determine the filter coefficient so as to remove only the frequency component corresponding to the carrier having poor reception quality at the communication partner from the frequency component included in the peak component of the multicarrier signal.

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

(Embodiment 1)
FIG. 1 is a block diagram showing a main configuration of the multicarrier communication apparatus according to Embodiment 1 of the present invention. As shown in FIG. 1, the multicarrier communication apparatus according to the present embodiment includes an S / P (Serial / Parallel) conversion unit 101, an IFFT (Inverse Fast Fourier Transform) unit 102, P / S (Parallel / Serial) conversion unit 103, delay unit 104, limiter 105, subtraction unit 106, filter 107, subtraction unit 108, transmission unit 109, reception unit 110, quality information demodulation unit 111, and filter A coefficient determination unit 112 is included.

  The S / P conversion unit 101 performs S / P conversion on transmission data and outputs parallel data superimposed on each of a plurality of carriers.

  The IFFT unit 102 performs inverse fast Fourier transform on the parallel data output from the S / P conversion unit 101 to output a time-domain signal in which the parallel data is superimposed on a plurality of carriers.

  P / S conversion section 103 P / S converts the time domain signal output from IFFT section 102, and outputs a serial multicarrier signal. This multicarrier signal has peak power.

  The delay unit 104 outputs a multicarrier signal by delaying by a time required for filtering to suppress peak power by each processing block described later.

  The limiter 105 performs a predetermined threshold comparison on the amplitude of the multicarrier signal output from the P / S converter 103. If the amplitude is less than the predetermined threshold, the limiter 105 outputs the amplitude of the multicarrier signal as it is. If is greater than or equal to a predetermined threshold, the predetermined threshold is output. That is, the limiter 105 outputs an amplitude that is equal to or less than a predetermined threshold of the multicarrier signal.

  The subtracting unit 106 subtracts the output of the limiter 105 from the multicarrier signal and outputs only the peak component included in the multicarrier signal.

  The filter 107 performs band limitation by filtering on the peak component, and outputs a band component that is band limited (hereinafter referred to as “filtered peak component”). The filter 107 is set with the filter coefficient determined by the filter coefficient determination unit 112 as described later.

  The subtracting unit 108 subtracts the filtered peak component from the multicarrier signal output from the delay unit 104 to suppress the peak power.

  Transmitting section 109 performs predetermined radio transmission processing (D / A conversion, up-conversion, etc.) on the multicarrier signal after peak power suppression, and transmits it to a communication partner (not shown) via an antenna.

  The receiving unit 110 receives a signal transmitted from a communication partner (not shown) via an antenna, and performs predetermined radio reception processing (down-conversion, A / D conversion, etc.).

  The quality information demodulator 111 demodulates the quality information for each carrier included in the received signal. That is, in this embodiment, a communication partner (not shown) measures the reception quality (for example, SINR (Signal to Interference and Noise Ratio) or BER (Bit Error Ratio)) of each carrier of the multicarrier signal. The measurement results are fed back as quality information. Then, the quality information demodulator 111 demodulates the fed back quality information.

  The filter coefficient determination unit 112 determines a filter coefficient that passes only a band of a carrier with poor reception quality (hereinafter also simply referred to as “poor carrier”) at a communication partner (not shown). That is, in the present embodiment, the filter coefficient determining unit 112 refers to the quality information for each carrier demodulated by the quality information demodulating unit 111, and determines a predetermined number from the one with poor reception quality at a communication partner (not shown). A carrier is selected as a poor carrier, and a filter coefficient that passes only the bad carrier is determined. In this way, by selecting a carrier with relatively poor reception quality rather than a threshold comparison of reception quality, even if the reception quality of all carriers is relatively good, a predetermined number of carriers are poor. Therefore, the filter 107 always outputs a frequency component corresponding to a poor carrier. For this reason, subtraction of the peak component described later is always possible.

  Note that the filter coefficient determination unit 112 calculates the average value of the quality information for each carrier when receiving quality information reports from a plurality of communication partners (not shown), and selects a predetermined number of carriers from the lower average value. It may be selected, or a predetermined number of carriers may be selected by referring to the quality information of the communication partner that has reported the worst quality information for each carrier. In addition, a predetermined number of carriers may be selected from those with poor reception quality for each communication partner, and finally, carriers selected for more than half of the communication partners may be selected as poor carriers.

  Furthermore, the filter coefficient determination unit 112 compares, for example, the quality information of a poor carrier with two different threshold values A and B (threshold value A <threshold value B), and particularly bad carrier and quality information whose quality information is less than the threshold value A. May be classified into slightly inferior carriers having a threshold value A or more and less than the threshold value B and slightly inferior carriers having quality information equal to or more than the threshold value B, and the filter coefficient may be determined by weighting the classification of each carrier. That is, for example, a filter coefficient may be determined such that a particularly bad carrier band passes completely through the filter 107, and a slightly worse carrier band passes through the filter 107 after halving the power. In this way, the filter coefficient can be determined flexibly and finely, and more precise control according to the quality information for each carrier becomes possible.

  2 and 3 are block diagrams illustrating an example of the internal configuration of the filter 107. FIG. FIG. 2 is an example of a filter that performs band limitation on a frequency domain signal, and FIG. 3 is an example of a filter that performs band limitation by performing a convolution operation on a time waveform.

  A filter 107 shown in FIG. 2 includes an FFT unit 1071 that converts a peak component into a frequency domain signal by fast Fourier transform, a multiplier 1072 that multiplies each frequency component included in the peak component by a filter coefficient, and each multiplication. An IFFT unit 1073 that performs inverse fast Fourier transform on the output of the unit 1072 to convert it into a signal in the time domain.

  On the other hand, the filter 107 shown in FIG. 3 includes a delay element 1074 for storing individual unit signals constituting a peak component in time series, a multiplier 1075 for multiplying the output of each delay element 1074 by a filter coefficient, and each multiplication. An adder 1076 for adding the outputs of the adder 1075 and outputting the filtered peak component is provided.

  In these filters 107, by adjusting the filter coefficient to be multiplied by the multiplier 1072 or the multiplier 1075, it is possible to perform band limitation that allows only a desired band to pass in the input peak component. In the present embodiment, as described above, the filter coefficient determination unit 112 determines the filter coefficient, and only the carrier band having poor reception quality at the communication partner passes through the filter 107. Yes.

  Next, the operation of the multicarrier communication apparatus configured as described above will be specifically described with reference to FIGS. In the following, for convenience of explanation, it is assumed that a multicarrier signal including only two carriers, carrier C1 and carrier C2, is transmitted from the multicarrier communication apparatus shown in FIG.

  First, transmission data is subjected to S / P conversion by the S / P converter 101 and converted into two series of parallel data corresponding to the number of carriers. The two series of parallel data are subjected to inverse fast Fourier transform by the IFFT unit 102, and the respective series of data are superimposed on the carrier C1 and the carrier C2. Then, the data superimposed on each carrier is P / S converted by the P / S conversion unit 103 to generate a multicarrier signal in which the data is superimposed on the carrier C1 and the carrier C2, respectively.

  The multicarrier signal generated here is a signal obtained by adding the powers of the carriers C1 and C2, and includes a peak component 201 as shown in FIG. 4A, for example. Further, as shown in FIG. 4B, the bands of the multicarrier signal are bands of the carrier C1 and the carrier C2 having the same power.

  The multicarrier signal output from the P / S conversion unit 103 is input to the limiter 105 and the subtraction unit 106, and only the amplitude equal to or less than a predetermined threshold is output by the limiter 105, and the output amplitude is output from the subtraction unit 106. Subtracted from the multicarrier signal. That is, only the peak component 201 is output from the subtractor 106 to the filter 107 as shown in FIG. As shown in FIG. 5B, the band of the peak component 201 substantially overlaps the band of the multicarrier signal.

  On the other hand, a signal from a communication partner is received by the receiving unit 110, and quality information for each carrier included in the received signal is demodulated by the quality information demodulating unit 111. As described above, in this embodiment, a communication partner (not shown) that receives the multicarrier signal transmitted from the multicarrier communication apparatus shown in FIG. 1 measures the reception quality for each carrier, and this measurement result Is reported to the multicarrier communication apparatus shown in FIG. 1 as quality information. Therefore, the quality information is demodulated by the quality information demodulator 111, whereby the reception quality for each carrier at the communication partner is acquired. The quality information for each carrier is output to the filter coefficient determination unit 112.

  Then, the filter coefficient determination unit 112 selects a carrier having inferior quality information, and determines the filter coefficient of the filter 107 that passes only the band of the selected carrier. In selecting an inferior carrier, for example, a predetermined number of carriers may be selected as an inferior carrier from those with inferior quality information. Here, the description will be continued assuming that the carrier C1 is selected as a poor carrier. That is, the filter coefficient determination unit 112 determines the filter coefficient so that only the band of the carrier C1 passes through the filter 107. The determined filter coefficient is set in the filter 107.

  Since the peak component 201 is output to the filter 107 as described above, the peak component 201 is band-limited by the filter 107, and only the band of the carrier C1 is output from the filter 107 as the post-filter peak component. . That is, out of the peak component bands shown in FIG. 5B, only the band of the carrier C1 indicated by the oblique lines in FIG. The output from the filter 107 is shown as the post-filter peak component 202 in FIG. 6A in the time domain. The post-filter peak component 202 corresponds to the frequency component of the carrier C1 with poor quality information in the peak component 201.

  The filtered peak component 202 that has been subjected to the filtering process as described above is subtracted from the multicarrier signal by the subtracting unit 108. At this time, since the multicarrier signal output from the P / S conversion unit 103 is delayed by the delay unit 104 by the time required for the filtering process, the timing between the multicarrier signal and the post-filter peak component 202 is It is properly adjusted.

  As a result, the multicarrier signal output from the subtraction unit 108 has peak power suppressed as shown in FIG. 7A, and in the frequency domain, as shown in FIG. Only the power of the frequency corresponding to the poor carrier C1 is low. That is, since the power of only the poor carrier C1 is suppressed, the data superimposed on the carrier C2 is not lost without being attenuated at all for the carrier C2 with good reception quality at the communication partner. Therefore, only the carrier C1 that cannot be expected to maintain the quality on the propagation path is attenuated for peak power suppression, and conversely, the carrier C2 with good reception quality at the communication partner is not attenuated, and the reception quality by peak power suppression is reduced. Can be minimized.

  As described above, according to the present embodiment, filtering is used to subtract only the frequency component of the carrier whose reception quality at the communication partner is inferior from the peak component included in the multicarrier signal from the multicarrier signal. The influence on the reception quality due to the peak power suppression can be suppressed, and the deterioration of the reception quality of the multicarrier signal can be reduced.

(Embodiment 2)
The feature of Embodiment 2 of the present invention is that, instead of receiving quality information for each carrier transmitted from the communication partner, the carrier number transmitted from the communication partner is received, and the frequency component of this carrier is changed to the peak component. It is a point to remove from.

  FIG. 8 is a block diagram showing a main configuration of the multicarrier communication apparatus according to the present embodiment. In the figure, the same parts as those in FIG. The multicarrier communication apparatus shown in FIG. 8 has a carrier number demodulator 301 instead of the quality information demodulator 111 of the multicarrier communication apparatus shown in FIG.

  Carrier number demodulating section 301 demodulates the carrier number of a poor carrier included in the received signal. That is, in the present embodiment, a communication partner (not shown) measures the reception quality of each carrier of the multicarrier signal, selects an inferior carrier from this measurement result, and feeds back the carrier number of the selected carrier. . Then, the carrier number demodulator 301 demodulates the fed back carrier number. Note that the poor carrier selection in the communication partner (not shown) may be performed in the same manner as the poor carrier selection in the filter coefficient determination unit 112 of the multicarrier communication apparatus of the first embodiment. That is, a communication partner (not shown) measures reception quality for each carrier, and selects a predetermined number of carriers as poor carriers from those with poor reception quality.

  As described above, in the present embodiment, the information fed back from the communication partner to the multicarrier communication apparatus is not the quality information for each carrier but the carrier number of the poor carrier, so the side information amount is reduced and the line is reduced. The burden on the capacity can be reduced.

  In the present embodiment, filter coefficient determination section 112 determines a filter coefficient that passes only the carrier having the carrier number obtained by demodulation by carrier number demodulation section 301.

  Note that the filter coefficient determination unit 112 may determine filter coefficients that allow all bad carriers to pass when half of the bad carrier signals are reported from a plurality of communication partners (not shown). You may determine the filter coefficient which passes the carrier of the carrier number reported from the above communication other party.

  Next, the operation of the multicarrier communication apparatus configured as described above will be described.

  First, transmission data is S / P converted by the S / P conversion unit 101 and converted into parallel data corresponding to the number of carriers, as in the first embodiment. The parallel data is subjected to inverse fast Fourier transform by the IFFT unit 102, and each series of data is superimposed on a plurality of carriers. Then, the data superimposed on each carrier is P / S converted by the P / S conversion unit 103 to generate a multicarrier signal in which the data is superimposed on a plurality of carriers.

  The multicarrier signal output from the P / S conversion unit 103 is input to the limiter 105 and the subtraction unit 106, and only the amplitude equal to or less than a predetermined threshold is output by the limiter 105, and the output amplitude is output from the subtraction unit 106. The peak component is output to the filter 107 after subtraction from the multicarrier signal.

  On the other hand, a signal from a communication partner is received by the receiving unit 110, and a carrier number of an inferior carrier included in the received signal is demodulated by the carrier number demodulating unit 301. As described above, in this embodiment, a communication partner (not shown) that receives the multicarrier signal transmitted from the multicarrier communication apparatus shown in FIG. 8 measures the reception quality for each carrier and selects a poor carrier. The carrier number of the selected carrier is reported to the multicarrier communication apparatus shown in FIG. Therefore, the carrier number demodulating section 301 demodulates the carrier number included in the received signal, so that a carrier with poor reception quality at the communication partner is determined. The carrier number of the inferior carrier is output to the filter coefficient determination unit 112.

  Then, the filter coefficient determination unit 112 determines the filter coefficient of the filter 107 that passes only a poor carrier band. Since the peak component is output to the filter 107 as described above, the peak component is band-limited by the filter 107, and only a poor carrier band is output from the filter 107 as the post-filter peak component.

  The filtered peak component subjected to the filtering process as described above is subtracted from the multicarrier signal by the subtracting unit 108. At this time, since the multicarrier signal output from the P / S conversion unit 103 is delayed by the delay unit 104 by the time required for the filtering process, the timing of the multicarrier signal and the filtered peak component is appropriate. Has been adjusted.

  As a result, the multicarrier signal output from the subtracting unit 108 has a peak power suppressed, and only the power of the frequency corresponding to the poor carrier is low in the frequency domain. In other words, since the power of only poor carriers is suppressed, carriers with good reception quality at the communication partner are not attenuated at all and data is not lost. Therefore, only poor carriers that cannot be expected to maintain quality on the propagation path are attenuated for peak power suppression in the first place, and on the contrary, carriers with good reception quality at the communication partner are not attenuated, and reception quality by peak power suppression is reduced. Can be minimized.

  As described above, according to the present embodiment, filtering is used to subtract only the frequency component of the carrier whose reception quality at the communication partner is inferior from the peak component included in the multicarrier signal from the multicarrier signal. The influence on the reception quality due to the peak power suppression can be suppressed, and the deterioration of the reception quality of the multicarrier signal can be reduced. In addition, since the communication partner selects a poor carrier and feeds back the carrier number of the selected carrier to the multicarrier communication apparatus, the amount of side information can be reduced and the burden on the line capacity can be reduced.

(Embodiment 3)
A feature of Embodiment 3 of the present invention is that transmission of a carrier with poor reception quality at the communication partner is stopped.

  FIG. 9 is a block diagram showing a main configuration of the multicarrier communication apparatus according to the present embodiment. In the figure, the same parts as those in FIG. The multicarrier communication apparatus shown in FIG. 9 has a configuration in which a transmission ON / OFF unit 401 is added to the multicarrier communication apparatus shown in FIG.

  The transmission ON / OFF unit 401 stops transmission of a series of data superimposed on a carrier with low reception quality at a communication partner (not shown). That is, the transmission ON / OFF unit 401 refers to the quality information for each carrier demodulated by the quality information demodulating unit 111, selects, for example, a carrier whose quality information is less than a predetermined threshold value, and selects from the S / P conversion unit 101 Transmission of the data of the series superimposed on the selected carrier among the output parallel data is stopped.

  As described above, in this embodiment, since transmission of data superimposed on a carrier with low quality information reported from a communication partner is stopped, even if the power of this carrier is attenuated to suppress peak power, Does not affect the data transmission quality.

  Next, the operation of the multicarrier communication apparatus configured as described above will be specifically described with reference to FIG. In the following, for convenience of explanation, it is assumed that a multicarrier signal including eight carriers C1 to C8 is transmitted from the multicarrier communication apparatus shown in FIG.

  In the present embodiment, first, a signal from a communication partner is received by receiving section 110, and quality information for each carrier included in the received signal is demodulated by quality information demodulating section 111. The quality information for each carrier obtained by demodulation is output to the filter coefficient determination unit 112 and the transmission ON / OFF unit 401.

  Similarly to the first embodiment, the transmission data is S / P converted by the S / P conversion unit 101 and converted into parallel data corresponding to the number of carriers. The parallel data is output to the transmission ON / OFF unit 401, and the transmission ON / OFF unit 401 stops transmission of data superimposed on some carriers. Specifically, transmission of data to be superimposed on the carrier corresponding to the carrier C1 to C8 quality information obtained by the quality information demodulator 111 that is lower than a predetermined threshold is stopped. Here, the description is continued assuming that the quality information of the carrier C7 is less than a predetermined threshold. That is, the transmission ON / OFF unit 401 stops the transmission of data superimposed on the carrier C7, and the power of the carrier C7 becomes 0 as shown in FIG.

  Parallel data other than the data superimposed on the carrier C7 is subjected to inverse fast Fourier transform by the IFFT unit 102, and the respective series of data is superimposed on the carriers C1 to C6 and C8. Then, the data superimposed on each carrier is P / S converted by the P / S conversion unit 103 to generate a multicarrier signal in which the data is superimposed on each of the carriers C1 to C6 and C8. However, at this time, since the signals of the carriers C1 to C6 and C8 are convoluted to generate distortion components, the power of the carrier C7 of the generated multicarrier signal is not exactly zero.

  The multicarrier signal output from the P / S conversion unit 103 is input to the limiter 105 and the subtraction unit 106, and only the amplitude equal to or less than a predetermined threshold is output by the limiter 105, and the output amplitude is output from the subtraction unit 106. The peak component is output to the filter 107 after subtraction from the multicarrier signal.

  The peak component output here includes a peak component having a frequency component as shown in FIG. 10B in the frequency domain. In FIG. 10B, the power is not 0 even in the band outside the carrier C7 and the carriers C1 to C8 due to the distortion component due to the convolution described above.

  Similarly to the first embodiment, the filter coefficient determination unit 112 determines the filter coefficient of the filter 107 that allows only a poor carrier band to pass. Here, the description will be continued assuming that the carrier C7 is selected as a poor carrier. That is, the filter coefficient determination unit 112 determines the filter coefficient so that only the band of the carrier C7 passes through the filter 107. The determined filter coefficient is set in the filter 107.

  Since the peak component is output to the filter 107 as described above, the peak component is band-limited by the filter 107, and only the band of the carrier C7 is output from the filter 107 as the post-filter peak component. That is, out of the peak components shown in FIG. 10B, only the band of the carrier C7 indicated by the oblique lines in FIG.

  The filtered peak component subjected to the filtering process as described above is subtracted from the multicarrier signal by the subtracting unit 108. At this time, since the multicarrier signal output from the P / S conversion unit 103 is delayed by the delay unit 104 by the time required for the filtering process, the timing of the multicarrier signal and the filtered peak component is appropriate. Has been adjusted.

  As a result, the multicarrier signal output from the subtracting unit 108 has only low power at a frequency corresponding to the poor carrier C7, as shown in FIG. 10 (d). In other words, since the power of only the poor carrier C7 on which data is not superimposed is suppressed, the carriers C1 to C6 and C8 with good reception quality at the communication partner are not attenuated at all and the transmission data is not stopped ( That is, all transmitted data) is not lost. At the same time, the power of the frequency component corresponding to the carrier C7 in the peak component is attenuated, so that the peak power of the entire multicarrier signal is suppressed.

  As described above, according to the present embodiment, filtering is used to subtract only the frequency component of the carrier whose reception quality at the communication partner is inferior from the peak component included in the multicarrier signal from the multicarrier signal. The influence on the reception quality due to the peak power suppression can be suppressed, and the deterioration of the reception quality of the multicarrier signal can be reduced. In addition, since transmission of data superimposed on a carrier whose reception quality at a communication partner is less than a predetermined threshold is stopped, it is possible to further reduce the influence of peak power suppression on data transmission quality.

  In the present embodiment, a case where both the poor carrier selected by the filter coefficient determination unit 112 and the carrier whose transmission of data superimposed by the transmission ON / OFF unit 401 is stopped is the carrier C7. Although described, the carriers selected in these processing blocks need not necessarily match.

  In Embodiments 1 to 3 described above, the quality information or carrier number for each carrier is reported from the communication partner, but a plurality of carriers are grouped and the quality information or group number for each group is reported. You may be made to do. In this case, the amount of side information for the multicarrier communication apparatus to determine a poor carrier can be reduced, the burden on the line capacity can be reduced, and the calculation amount in the multicarrier communication apparatus can be reduced. it can.

(Embodiment 4)
The feature of Embodiment 4 of the present invention is that, in the TDD (Time Division Duplex) method using the same frequency band in the uplink and downlink, the reception quality of each carrier is measured in its own device and removed from the peak component. The point is to determine the carrier corresponding to the frequency component.

  FIG. 11 is a block diagram showing a main configuration of the multicarrier communication apparatus according to the present embodiment. In the figure, the same parts as those in FIG. The multicarrier communication apparatus shown in FIG. 11 has a reception quality measurement unit 501 instead of the quality information demodulation unit 111 of the multicarrier communication apparatus shown in FIG.

  Reception quality measuring section 501 measures the reception quality for each carrier using the received signal. In the present embodiment, it is assumed that the multicarrier communication apparatus shown in FIG. 11 is used in a TDD mobile communication system, and the frequency of the line on which the multicarrier communication apparatus transmits and receives signals is the same. The reception quality for each carrier on one line is substantially equal to the reception quality for each carrier on the other line. Therefore, in the present embodiment, reception quality measuring section 501 indirectly acquires the reception quality for each carrier at the communication partner by measuring the reception quality for each carrier of the line on which the received signal is transmitted. Yes.

  Thus, in this embodiment, since the multicarrier communication apparatus acquires the reception quality for each carrier at the communication partner, side information becomes unnecessary, and the burden on the line capacity can be further reduced.

  Next, the operation of the multicarrier communication apparatus configured as described above will be described.

  First, transmission data is S / P converted by the S / P conversion unit 101 and converted into parallel data corresponding to the number of carriers, as in the first embodiment. The parallel data is subjected to inverse fast Fourier transform by the IFFT unit 102, and each series of data is superimposed on a plurality of carriers. Then, the data superimposed on each carrier is P / S converted by the P / S conversion unit 103 to generate a multicarrier signal in which the data is superimposed on a plurality of carriers.

  The multicarrier signal output from the P / S conversion unit 103 is input to the limiter 105 and the subtraction unit 106, and only the amplitude equal to or less than a predetermined threshold is output by the limiter 105, and the output amplitude is output from the subtraction unit 106. The peak component is output to the filter 107 after subtraction from the multicarrier signal.

  On the other hand, the signal from the communication partner is received by the receiving unit 110, and the reception quality is measured for each carrier by the reception quality measuring unit 501 using the received signal. As described above, in the present embodiment, it is assumed that the multicarrier communication apparatus shown in FIG. 11 is used in a TDD mobile communication system. Is obtained. The reception quality for each carrier is output to filter coefficient determination section 112.

  Then, the filter coefficient determination unit 112 selects a carrier having poor reception quality, and determines the filter coefficient of the filter 107 that passes only the band of the selected carrier. In selecting an inferior carrier, for example, a predetermined number of carriers may be selected as an inferior carrier from the one having a poor reception quality. The determined filter coefficient is set in the filter 107.

  Since the peak component is output to the filter 107 as described above, the peak component is band-limited by the filter 107, and only a poor carrier band is output from the filter 107 as the post-filter peak component.

  The filtered peak component subjected to the filtering process as described above is subtracted from the multicarrier signal by the subtracting unit 108. At this time, since the multicarrier signal output from the P / S conversion unit 103 is delayed by the delay unit 104 by the time required for the filtering process, the timing of the multicarrier signal and the filtered peak component is appropriate. Has been adjusted.

  As a result, the multicarrier signal output from the subtracting unit 108 has a peak power suppressed, and only the power of the frequency corresponding to the poor carrier is low in the frequency domain. In other words, since the power of only poor carriers is suppressed, carriers with good reception quality at the communication partner are not attenuated at all and data is not lost.

  As described above, according to the present embodiment, filtering is used to subtract only the frequency component of the carrier whose reception quality at the communication partner is inferior from the peak component included in the multicarrier signal from the multicarrier signal. The influence on the reception quality due to the peak power suppression can be suppressed, and the deterioration of the reception quality of the multicarrier signal can be reduced. Moreover, since the reception quality for each carrier at the communication partner is obtained indirectly from the received signal in the multicarrier communication apparatus, side information is not required, and the burden on the line capacity can be further reduced.

  The multicarrier communication apparatus according to the first aspect of the present invention includes a filter that band-limits a peak component included in a multicarrier signal in which data is superimposed on a plurality of carriers, and reception quality at a communication partner of the plurality of carriers. Acquisition means for acquiring information on inferior carriers that do not satisfy a predetermined criterion, determination means for determining filter coefficients of the filter in accordance with the acquired information on inferior carriers, and the determined filter coefficients are set A configuration having subtracting means for subtracting the peak component after passing through the filter from the multicarrier signal and transmitting means for transmitting the multicarrier signal after subtraction of the peak component is adopted.

  According to this configuration, in order to band-limit the peak component by the filter in which the filter coefficient determined according to the bad carrier information is set, and to subtract the band component after band limitation from the multicarrier signal and transmit, for example, Of the peak components, only the frequency component corresponding to the inferior carrier can be subtracted from the multicarrier signal, and the carrier with good reception quality at the communication partner is not attenuated at all, and the superimposed data is not lost. For this reason, the influence on the reception quality by the peak power suppression using filtering can be suppressed, and the deterioration of the reception quality of the multicarrier signal can be reduced.

  The multicarrier communication apparatus according to a second aspect of the present invention is the multicarrier communication apparatus according to the first aspect, wherein the determination means uses a filter coefficient that allows the filter to pass only the band of the inferior carrier out of the entire band of the peak component. Take the configuration to determine.

  According to this configuration, since the filter coefficient that passes only the band of the poor carrier is determined, only the frequency component corresponding to the bad carrier among the peak components can be subtracted from the multicarrier signal.

  The multicarrier communication apparatus according to a third aspect of the present invention is the multicarrier communication apparatus according to the first aspect, wherein the acquisition means includes reception means for receiving side information relating to reception quality for each carrier measured at a communication partner. Take.

  According to this configuration, since the side information related to the reception quality for each carrier at the communication partner is received, it is possible to accurately determine the poor carrier using the side information.

  The multicarrier communication apparatus according to a fourth aspect of the present invention employs a configuration in which, in the third aspect, the receiving means receives side information relating to reception quality for each group obtained by grouping a plurality of carriers. .

  According to this configuration, since side information for each group of a plurality of carriers is received, the amount of side information can be reduced to reduce the load on the line capacity, and the calculation amount for determining the filter coefficient can be reduced. can do.

  The multicarrier communication apparatus according to a fifth aspect of the present invention is the multicarrier communication apparatus according to the first aspect, wherein the acquisition means includes reception means for receiving quality information indicating reception quality for each carrier measured at a communication partner. Then, a configuration is adopted in which a predetermined number of carriers are used as poor carriers in order from the poor reception quality indicated by the quality information.

  According to this configuration, quality information indicating the reception quality for each carrier is received, and a predetermined number of carriers are determined to be poor carriers from the poor reception quality. The peak power can be suppressed even if the reception quality of the carrier is relatively good.

  The multicarrier communication apparatus according to a sixth aspect of the present invention is the multicarrier communication apparatus according to the first aspect, wherein the acquisition means includes a reception means for receiving a signal including a carrier number of an inferior carrier determined by a communication partner, A configuration is adopted in which the carrier corresponding to the received carrier number is a poor carrier.

  According to this configuration, since the carrier corresponding to the received carrier number is an inferior carrier, the amount of side information can be reduced compared with the case where the quality information of all carriers is transmitted from the communication partner, and the line capacity Can be reduced.

  The multicarrier communication apparatus according to a seventh aspect of the present invention is the multicarrier communication apparatus according to the first aspect, wherein the acquisition means receives a signal transmitted from a communication partner, and receives each carrier using the received signal. And measuring means for measuring the quality, and adopting a configuration in which a predetermined number of carriers are determined to be inferior carriers from the one having a poor measured reception quality.

  According to this configuration, since a predetermined number of carriers are determined as poor carriers from those with poor reception quality measured using a received signal from the communication partner, it is not necessary to receive side information from the communication partner, and the line capacity is reduced. Can be further reduced.

  The multicarrier communication apparatus according to an eighth aspect of the present invention further includes a stop means for stopping transmission of data superimposed on a carrier whose reception quality at a communication partner is less than a predetermined threshold in the first aspect. Take the configuration.

  According to this configuration, since transmission of data superimposed on a carrier whose reception quality is less than a predetermined threshold is stopped, data is not superimposed on a frequency band subtracted from the multicarrier signal for peak power suppression. The possibility is high, and the influence on the transmission quality of data due to peak power suppression can be further reduced.

  A multicarrier communication apparatus according to a ninth aspect of the present invention is the multicarrier communication apparatus according to the first aspect, wherein the determining means determines a filter coefficient that weights each bad carrier according to the reception quality at the communication partner. Take.

  According to this configuration, each poor carrier is weighted according to the reception quality to determine the filter coefficient, so that the filter coefficient can be determined flexibly and finely, and more precise control according to the quality information for each carrier Is possible.

  The peak power suppression method according to the tenth aspect of the present invention is a peak power suppression method for suppressing peak power by performing band limiting filtering on peak components included in a multicarrier signal in which data is superimposed on a plurality of carriers. A step of acquiring information on a bad carrier whose reception quality at a communication partner does not satisfy a predetermined standard among the plurality of carriers, and a step of determining a filter coefficient of a filter according to the information on the bad carrier acquired. The step of subtracting the peak component after passing through the filter in which the determined filter coefficient is set from the multicarrier signal and the step of transmitting the multicarrier signal after subtraction of the peak component are included.

  According to this method, the peak component is band-limited by the filter in which the filter coefficient determined according to the bad carrier information is set, and the peak component after band limitation is subtracted from the multicarrier signal for transmission. Of the components, only the frequency component corresponding to the inferior carrier can be subtracted from the multicarrier signal, and carriers with good reception quality at the communication partner are not attenuated at all, and the superimposed data is not lost. For this reason, the influence on the reception quality by the peak power suppression using filtering can be suppressed, and the deterioration of the reception quality of the multicarrier signal can be reduced.

  The multicarrier communication apparatus and the peak power suppression method of the present invention can reduce deterioration of reception quality of multicarrier signals. For example, as a multicarrier communication apparatus and a peak power suppression method for suppressing peak power by filtering. Useful.

FIG. 2 is a block diagram showing a main configuration of the multicarrier communication apparatus according to Embodiment 1 of the present invention. FIG. 3 is a block diagram illustrating an example of an internal configuration of a filter according to the first embodiment. The block diagram which shows another example of the internal structure of the filter which concerns on Embodiment 1. FIG. (A) The figure which shows an example of the time domain waveform of the multicarrier signal which concerns on Embodiment 1 (b) The figure which shows an example of the frequency domain waveform of the multicarrier signal which concerns on Embodiment 1 (A) The figure which shows an example of the time domain waveform of the peak component which concerns on Embodiment 1 (b) The figure which shows an example of the frequency domain waveform of the peak component which concerns on Embodiment 1. (A) The figure which shows an example of the time domain waveform of the peak component after the band limitation which concerns on Embodiment 1 (b) The figure which shows an example of the frequency domain waveform of the peak component after the band limitation which concerns on Embodiment 1 (A) The figure which shows an example of the time domain waveform of the multicarrier signal after peak power suppression which concerns on Embodiment 1 (b) An example of the frequency domain waveform of the multicarrier signal after peak power suppression which concerns on Embodiment 1 Illustration The block diagram which shows the principal part structure of the multicarrier communication apparatus which concerns on Embodiment 2 of this invention. The block diagram which shows the principal part structure of the multicarrier communication apparatus which concerns on Embodiment 3 of this invention. (A) Diagram showing an example of a multicarrier signal according to Embodiment 3 (b) Diagram showing an example of a peak component according to Embodiment 3 (c) Example of peak component after band limitation according to Embodiment 3 (D) which shows an example of the multicarrier signal after the peak power suppression which concerns on Embodiment 3 The block diagram which shows the principal part structure of the multicarrier communication apparatus which concerns on Embodiment 4 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 S / P conversion part 102 IFFT part 103 P / S conversion part 104 Delay part 105 Limiter 106, 108 Subtraction part 107 Filter 109 Transmission part 110 Reception part 111 Quality information demodulation part 112 Filter coefficient determination part 301 Carrier number demodulation part 401 Transmission ON / OFF unit 501 Reception quality measurement unit

Claims (10)

A filter that band-limits a peak component included in a multicarrier signal in which data is superimposed on a plurality of carriers;
An acquisition means for acquiring information on a bad carrier whose reception quality at a communication partner of the plurality of carriers does not satisfy a predetermined standard;
Determining means for determining a filter coefficient of the filter according to the acquired information of the poor carrier;
Subtracting means for subtracting from the multicarrier signal a peak component after passing through the filter in which the determined filter coefficient is set;
Transmitting means for transmitting the multicarrier signal after subtraction of the peak component;
A multi-carrier communication apparatus comprising: The determining means includes
The multicarrier communication apparatus according to claim 1, wherein the filter determines a filter coefficient that passes only the band of the poor carrier out of the entire band of the peak component. The acquisition means includes
The multicarrier communication apparatus according to claim 1, further comprising receiving means for receiving side information relating to reception quality for each carrier measured at a communication partner. The receiving means includes
4. The multicarrier communication apparatus according to claim 3, wherein side information relating to reception quality for each group obtained by grouping a plurality of carriers is received. The acquisition means includes
Receiving means for receiving quality information indicating reception quality for each carrier measured at a communication partner;
2. The multicarrier communication apparatus according to claim 1, wherein a predetermined number of carriers are determined to be inferior carriers from the one having a poor reception quality indicated by the quality information. The acquisition means includes
Receiving means for receiving a signal including a carrier number of an inferior carrier determined at a communication partner,
The multicarrier communication apparatus according to claim 1, wherein a carrier corresponding to the received carrier number is a poor carrier. The acquisition means includes
Receiving means for receiving a signal transmitted from a communication partner;
Measuring means for measuring the reception quality for each carrier using the received signal,
2. The multicarrier communication apparatus according to claim 1, wherein a predetermined number of carriers are determined to be inferior carriers, starting from the one having the poorer received quality.   The multicarrier communication apparatus according to claim 1, further comprising a stopping unit that stops transmission of data superimposed on a carrier whose reception quality at a communication partner is less than a predetermined threshold. The determining means includes
2. The multicarrier communication apparatus according to claim 1, wherein a filter coefficient weighted to each bad carrier is determined according to reception quality at a communication partner. A peak power suppression method for suppressing peak power by performing band limiting filtering on peak components included in a multicarrier signal in which data is superimposed on a plurality of carriers,
Obtaining information of a poor carrier whose reception quality at a communication partner of the plurality of carriers does not satisfy a predetermined standard;
Determining a filter coefficient of the filter according to the acquired information of the bad carrier;
Subtracting from the multicarrier signal a peak component after passing through the filter in which the determined filter coefficient is set;
Transmitting a multicarrier signal after subtraction of peak components;
A peak power suppression method characterized by comprising:

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