WO2005034400A1 - Transmitting apparatus and peak suppressing method - Google Patents

Abstract

A transmitting apparatus capable of improving the throughput of the whole system by using the frequencies of a part of a communication band to perform peak suppression. In this apparatus, a modulating part (102) performs an adaptive modulation of data to be transmitted. A combining part (103) combines the waveform of the transmitted data and an inverted replica thereof to suppress the peaks that are above a threshold level. A peak determining part (111) determines whether the transmitted signal has any peaks that are above the threshold level. If there exist such peaks that are above the threshold level, an inverted-replica generating part (112) extracts the waveform having the peaks that are above the threshold level, and generates an inverted replica having a waveform whose characteristic is opposite to the extracted waveform. A sub-band selecting part (114) selects the frequencies of subcarriers in which MCS of a low transmission efficiency has been selected, and outputs the inverted replica within the selected frequency range to the combining part (103).

Description

 Specification

 Transmission apparatus and peak suppression method

 Technical field

 The present invention relates to a transmission device and a peak suppression method, and for example, to a transmission device and a peak suppression method when transmitting a transmission signal by an OFDM method.

 Background art

 [0002] Conventionally, a multicarrier communication apparatus using the OFDM scheme has attracted attention as a device capable of realizing high-speed wireless transmission because it is resistant to multipath and fading and can perform high-quality communication. In OFDM communication, since transmission data is converted into parallel data and then transmitted by being superimposed on a plurality of subcarriers, there is no correlation for each subcarrier. For this reason, if the phases of the subcarriers overlap, the OFDM symbol will have an extremely large signal amplitude. As described above, if the peak voltage of a signal increases during transmission due to the overlapping of the phases of the subcarriers, an amplifier having a dynamic range that includes the peak power when amplifying the transmission signal is required. As power consumption increases, power consumption increases. Furthermore, if the peak power of the signal increases during transmission, an amplifier that can maintain linearity in a large area is required, so an expensive amplifier is required.

 [0003] For this reason, in the related art, a method of suppressing peak power by performing an amplitude limitation process for reducing the amplitude of the entire transmission signal using a limiter (for example, Patent Document 1), and only a peak. There is known a method of performing a process called clipping for suppressing the peak voltage.

 [0004] In the case of suppressing such a peak, there is known a transmitting apparatus that transmits the information with the peak suppressed included in the data. The receiving device that has received the data transmitted from such a transmitting device can decode the data without error by restoring the suppressed peak using the peak suppressed information.

[0005] On the other hand, in OFDM communication, the base station apparatus has the communication terminal apparatus report the reception quality of each subcarrier in the communication terminal apparatus, and based on the reported reception quality. Therefore, a system is used that allocates an appropriate number of subcarriers to each user (frequency division user multiplexing) and selects MCS (Modulation Coding Schemes) for each subcarrier. That is, based on the channel quality, the base station apparatus allocates, to each communication terminal apparatus, a subcarrier having the highest frequency use efficiency that can satisfy the desired communication quality (for example, the lowest transmission rate and error rate), and By selecting high-speed MCS for the carrier and transmitting data, high-speed data communication is performed for many users. Patent Document 1: JP-A-9-18451

 Disclosure of the invention

 Problems to be solved by the invention

[0006] However, in the conventional transmitting apparatus and the peak suppressing method, the information of the peak suppressing is included in the transmission data without considering the MCS of each subcarrier, so that the carrier component of high MCS is suppressed. In such a case, there is a problem that the throughput of the entire system is greatly deteriorated.

 [0007] An object of the present invention is to improve the throughput of the entire system by performing peak suppression using some frequencies in a communication band.

 Means for solving the problem

 [0008] A transmitting apparatus according to the present invention is a transmitting apparatus that transmits a frequency-division multiplexed transmission signal based on reception quality information indicating the reception quality of a communication partner, and determines a MCS parameter for each frequency. Means, a detecting means for detecting a peak in the transmission signal, a generating means for generating a waveform having an inverse characteristic of the peak waveform, and an MCS parameter having the lowest transmission efficiency among the MCS parameters determined for each frequency. At the corresponding frequency, a configuration is adopted that includes a synthesizing unit that synthesizes the waveform of the inverse characteristic with the waveform of the transmission signal, and a transmitting unit that transmits the transmission signal synthesized with the waveform of the inverse characteristic.

A peak suppression method of the present invention is a peak suppression method for suppressing a peak in a frequency-division multiplexed transmission signal based on reception quality information indicating reception quality of a communication partner, and determines an MCS parameter for each frequency. Detecting a peak in the transmission signal, generating a waveform having an inverse characteristic of the peak waveform, and corresponding to the MCS parameter having the lowest transmission efficiency among the MCS parameters determined for each frequency. Synthesizing the waveform of the inverse characteristic with the waveform of the transmission signal at a frequency.

 The invention's effect

 [0010] According to the present invention, it is possible to improve the throughput of the entire system by performing peak suppression using a part of the frequencies in the communication band.

 Brief Description of Drawings

 FIG. 1 is a block diagram showing a configuration of a wireless communication apparatus according to Embodiment 1 of the present invention.

 FIG. 2 is a diagram showing an MCS table according to Embodiment 1 of the present invention.

 FIG. 3 is a flowchart showing an operation of the wireless communication apparatus according to Embodiment 1 of the present invention.

 FIG. 4 is a diagram showing a relationship between time and PAPR in a waveform of a transmission signal according to Embodiment 1 of the present invention.

 FIG. 5 is a diagram showing a relationship between time and amplitude in a waveform of a transmission signal according to Embodiment 1 of the present invention.

 FIG. 6 is a diagram showing a relationship between time and amplitude in a replica according to Embodiment 1 of the present invention.

FIG. 7 is a diagram showing a relationship between time and amplitude in an inverse replica according to Embodiment 1 of the present invention.

FIG. 8 is a diagram showing subcarriers according to Embodiment 1 of the present invention.

 FIG. 9 is a diagram showing a waveform after the FFT of the inverse replica according to the first embodiment of the present invention.

 FIG. 10 is a diagram showing a PAPR histogram in a transmission signal according to Embodiment 1 of the present invention.

FIG. 11 shows a relationship between EbZN and BER in a transmission signal according to Embodiment 1 of the present invention.

 0

 Figure

 FIG. 12 is a flowchart showing an operation of the wireless communication apparatus according to Embodiment 2 of the present invention.

 FIG. 13 is a diagram showing subcarriers according to Embodiment 2 of the present invention.

 FIG. 14 is a flowchart showing the operation of the wireless communication apparatus according to Embodiment 3 of the present invention.

 FIG. 15 is a flowchart showing an operation of the wireless communication apparatus according to Embodiment 3 of the present invention.

FIG. 16 shows a configuration of a wireless communication apparatus according to Embodiment 4 of the present invention. FIG. 17 shows a configuration of a wireless communication apparatus according to Embodiment 5 of the present invention. FIG. 18 shows an embodiment of the present invention. 5 is a flowchart showing the operation of the wireless communication apparatus according to the fifth embodiment. 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 configuration of wireless communication apparatus 100 according to Embodiment 1 of the present invention.

 [0014] Encoding unit 101 encodes transmission data at a predetermined coding rate based on the encoding ratio information input from transmission parameter determining unit 123, and outputs the encoded transmission data to modulation unit 102. .

 [0015] Modulation section 102 modulates the transmission data input from encoding section 101 by a predetermined modulation scheme based on the modulation scheme information input from transmission parameter determination section 123, and outputs the modulated transmission data to synthesis section 103. .

[0016] The synthesizing section 103 receives an input from the modulating section 102 based on the inverse replica information, which is information of the inverse characteristic waveform (hereinafter, referred to as "inverse replica") of the waveform equal to or higher than the threshold value input from the FFT section 116 The transmitted data waveform and the inverse replica are synthesized on the frequency axis and output to a serial Z-parallel (hereinafter, referred to as “SZP”) converter 104.

[0017] The SZP conversion unit 104 converts the transmission data input from the synthesis unit 103 from a serial data format to a parallel data format and performs an inverse Fourier transform (hereinafter referred to as "IFFT; Inverse Fast Fourier

Transform ”) section 105.

[0018] IFFT section 105, which is an inverse orthogonal transform means, performs IFFT on transmission data input from SZP conversion section 104, inserts a guard interval (hereinafter referred to as "GI") insertion section 106, and a maximum power to average power ratio (hereinafter, referred to as "GI"). Output as “PAPR; Peak to Average Power Ratio”.

 [0019] GI insertion section 106 inserts a GI into the transmission data input from IFFT section 105 and outputs the transmission data to wireless transmission processing section 107.

[0020] Wireless transmission processing section 107 transmits the transmission data input from GI insertion section 106 from antenna 108 after up-converting the baseband frequency power to a radio frequency and the like.

[0021] PAPR calculation section 109 calculates the PAPR from the transmission data after IFFT input from IFFT section 105, and outputs the calculation result to peak determination section 111.

[0022] Cutoff instructing section 110 is a threshold for deleting the amplitude of transmission data, and is value information. The PAPR information is output to peak determination section 111.

 The peak determination unit 111 serving as a peak detection unit compares the calculation result of the PAPR input from the PAPR calculation unit 109 with the value information input from the cutoff instructing unit 110, and compares the threshold! / ヽ value It is determined whether or not there is a peak indicating the above PAPR. Then, when there is a peak indicating PAPR equal to or greater than the threshold, peak determining section 111 outputs waveform information of transmission data equal to or greater than the threshold including the peak to inverse replica generating section 112.

 An inverse replica generation unit 112, which is a waveform generation unit, generates a waveform for canceling the input waveform information from the waveform information input from the peak determination unit 111, that is, generates an inverse replica and outputs the inverse replica information to the subband selection unit 114. Output to

 [0025] Subband instructing section 113, based on MCS information that is information of MCS (MCS parameters) input from transmission parameter determining section 123, assigns a subcarrier to which transmission data with the lowest transmission efficiency is allocated within a communication band. The sub-band selection unit 114 is instructed to select the frequency band of the sub-band configured.

 [0026] Subband selection section 114, which is a selection means, selects the specified subband instructed from subband instructing section 113 and inputs the selected subband from inverse replica generation section 112 in the frequency band of the selected subband. Only the inverse replica is output to the bandpass filter (hereinafter referred to as “BPF”) 115.

 [0027] Based on the inverse replica information input from subband selection unit 114, BPF 115 converts the inverse replica, which is the canceling waveform generated by inverse replica generation unit 112, from the sub replica designated by subband instruction unit 113 of the inverse replica. Unnecessary band components other than the frequency band of the band are removed and output to a Fourier transform (hereinafter referred to as “FFT; Fast Fourier Transform”) section 116.

 [0028] FFT section 116, which is orthogonal transform means, performs FFT on the inverse replica based on the inverse replica information input from subband selection section 114, and outputs the inverse replica to combining section 103.

[0029] Radio reception processing section 118 performs down-conversion of the reception signal received by antenna 117 to a baseband frequency, and outputs the result to GI removal section 119.

[0030] GI removing section 119 removes the received signal power GI input from wireless reception processing section 118 and outputs F

Output to FT section 120. [0031] FFT section 120 performs FFT on the received signal input from GI removal section 119 and outputs the signal to demodulation section 121.

 [0032] Demodulation section 121 demodulates the received signal input from FFT section 120 and outputs it to decoding section 122.

 [0033] Decoding section 122 decodes the received signal input from demodulation section 121, outputs the decoded signal to transmission parameter determining section 123, and obtains received data.

 [0034] Transmission parameter determination section 123 uses reception quality information such as CQI (Channel Quality Indicator), which is reception quality information indicating the reception quality of the communication terminal apparatus for each subcarrier, based on the reception data input from decoding section 122. Then, MCS indicating the combination of the modulation scheme and the coding rate is selected. That is, as shown in FIG. 2, the transmission parameter determining unit 123 has an MCS table in which the MCS is associated with the modulation scheme and the coding rate, and the CQI and the CQI reported from the communication terminal apparatus are The MCS is selected for each subcarrier by referring to the MCS table in consideration of the received power and the like. Then, transmission parameter determining section 123 outputs the MCS of each selected subcarrier to subband instructing section 113 as MCS information. Further, transmission parameter determination section 123 outputs modulation scheme information indicating the selected MCS modulation scheme to modulation section 102, and outputs coding rate information indicating the selected MCS coding rate to coding section 101. I do. In FIG. 2, the transmission efficiency of MCS increases in order from 0 to 7, and MCS7 shows the highest transmission efficiency.

 Next, an operation of suppressing the peak of wireless communication apparatus 100 will be described with reference to FIGS. FIG. 3 is a flowchart showing an operation of suppressing the peak of the wireless communication device 100.

[0036] First, IFFT section 105 performs an IFFT on transmission data (step ST301).

 Next, PAPR calculation section 109 measures PAPR (step ST302).

 Next, as shown in FIG. 4, the peak determination unit 111 determines whether or not there is a peak at which the PAPR is equal to or greater than the threshold value (PAPR) based on the threshold value input from the cutoff instruction unit 110 and the value information. Is determined for each symbol (step ST303).

[0039] If there is a peak whose PAPR is equal to or greater than the threshold value (X, the inverse replica generation unit 112 determines that the amplitude is equal to or smaller than the threshold value (see FIG. 5) in relation to the time and amplitude of the transmission signal. j8) The waveform information 501, 502, 503, and 504 whose amplitudes are equal to or less than the threshold value (-j8) are extracted, and as shown in FIG. A replica 603 of 503 and a replica 604 of waveform information 504 are generated (step ST 304).

 Next, as shown in FIG. 7, the inverse replica generation unit 112 has the inverse characteristics of the inverse replica 701 having the inverse characteristics of the replica 601, the inverse replica 702 having the inverse characteristics of the replica 602, and the replica 603. An inverse replica 704 having an inverse characteristic of the inverse replica 703 and the replica 604 is generated (step ST305).

 Next, subband selecting section 114 selects the subband specified by subband specifying section 113 (step ST306), and BPF 115 selects the subband within the frequency band of the subband specified by subband specifying section 113. Output only the inverse replica. Specifically, as shown in FIG. 8, the subband selection unit 114 selects MCS6 in FIG. 2 for transmission data allocated to each subcarrier in node 1 (subband) in the communication band F3. In addition to being modulated by 16QAM, transmission data allocated to each subcarrier in band 2 (subband) is modulated by QPSK by selecting MCS3! Select.

 Next, FFT section 116 performs an FFT on the selected inverse replica of band 2 (step ST 307). By performing an FFT on the inverse replica of band 2, a waveform as shown in FIG. 9 is obtained. Since the inverse replica of band 1 other than band 2 is not output from subband selection section 114, the waveform after FFT is only the solid line portion in FIG.

Next, combining section 103 combines the transmission signal and the inverse replica of band 2 that has been FFT (the waveform indicated by the solid line in FIG. 9) (step ST308). As described above, by combining the inverse replica and the transmission data in band 2, the possibility that an error occurs in the transmission data allocated to the subcarrier in band 2 increases. However, when combining an inverse replica and transmission data in band 2, compared to combining the inverse replica and transmission data in the entire communication band F3, the inverse replica and transmission data are combined in band 1. Combine! / ヽ! The degradation of the error characteristics of the entire transmission data is small by ヽ. Also, even if an error occurs in the transmission data of band 2, it is possible to decode the transmission data of band 2 without error by performing processing such as retransmission. The On the other hand, if the PAPR is not equal to or more than the threshold value) in step ST303, the combining of the inverse replica and the transmission signal is not performed!

 FIG. 10 and FIG. 11 show the results of the simulation. Fig. 10 is a diagram showing a PAPR histogram when the conventional peak suppression processing (clipping) is performed over the entire band, and Fig. 11 is a graph showing the conventional peak suppression threshold value when the threshold is varied. FIG. 4 is a diagram illustrating a relationship between a power-to-noise ratio per bit (EbZNo) and a BER.

 [0045] In Fig. 10, P1 shows a histogram of PAPR when peak suppression is performed with a threshold of 4 dB, and P2 shows a histogram of PAPR when peak suppression is performed with a threshold of 5 dB. P3 shows the histogram of PAPR when the peak is suppressed with a threshold of 6 dB, P4 shows the threshold! /, The histogram of PAPR when the peak is suppressed with a value of 7 dB, and P5 shows the histogram. P6 shows the histogram of PAPR when the peak is suppressed with a threshold value of 8 dB, P6 shows the histogram of PAPR when the peak is suppressed with a threshold of 9 dB, and P7 shows the peak with a threshold of 10 dB. P8 shows a histogram of PAPR in the case, and P8 shows a histogram of PAPR without peak suppression. From Fig. 10, it can be seen that PAPR larger than the threshold is eliminated by peak suppression. However, the elimination of the peak component causes the BER to deteriorate as shown in FIG.

 [0046] In FIG. 11, C1 is the difference between BER and Eb / N when the threshold is set to 4 dB.

 0 indicates the relationship, C2 indicates the relationship between BER and EbZ No when the threshold is set to 5 dB, and C3 indicates the BER and Eb / No when the threshold is set to 8 dB. It shows the relationship with. According to Fig. 11, the error rate is smaller when the threshold is set to 5 dB than when the threshold is set to 4 dB, and the threshold is set to 8 dB compared to when the threshold is set to 5 dB. In this case, the error rate becomes smaller. It can be seen from FIGS. 10 and 11 that if the threshold is reduced, the power BER that can reduce PAPR is degraded.

As described above, according to the first embodiment, a deterioration factor due to peak suppression can be assigned to subcarriers of MCS with low transmission efficiency, so that the throughput of the entire system can be improved. (Embodiment 2)

 FIG. 12 is a flowchart showing the operation when suppressing the peak of the wireless communication device. The wireless communication apparatus according to the second embodiment has the same configuration as in FIG. 1, and a description thereof will be omitted.

 The operation of suppressing the peak of the wireless communication device will be described using FIG. 12 and FIG.

 [0050] First, IFFT section 105 performs an IFFT on transmission data (step ST1201).

 Next, PAPR calculation section 109 measures PAPR (step ST1202).

 Next, as shown in FIG. 4, the peak determination unit 111 determines whether the PAPR is greater than the threshold (α) or more based on the threshold information input from the cutoff instruction unit 110 and the value information. Is determined (step ST1203).

 [0053] When PAPR occurs and a peak having a value (X or more) exists, subband selecting section 114 sets K = 0 (step ST1204).

 Next, sub-band selecting section 114 selects 選 択 sub-bands (where Ν is a natural number and is equal to or less than the total number of sub-bands in the communication band) by sub-band specifying section 113 (step ST1205), Output only the inverse replica in the frequency band of the selected 周波 数 subbands. For example, as shown in FIG. 13, the subband selection unit 114 selects MCS6 for transmission data allocated to each subcarrier of band 1 (subband) in the communication band, modulates the data with 16QAM, and The transmission data assigned to each subcarrier of node 2 (subband) selects MCS3 and is modulated by QPSK, and the transmission data assigned to each subcarrier of node 3 (subband) uses MCS3. If the frequency is selected and modulated by QPSK, then if the transmission efficiency is low and MCS is selected, band 2 is selected.

 Next, FFT section 116 performs FFT on the inverse replica of the selected frequency band of band 2 (step ST1206). By performing FFT on the inverse replica in band 2, a waveform as shown in Fig. 9 is obtained. Since the inverse replica other than the frequency band of band 2 is not output from subband selecting section 114, the waveform after FFT is only the solid line portion in FIG.

Next, synthesizing section 103 synthesizes the transmission signal and the inverse replica subjected to FFT (the waveform indicated by the solid line in FIG. 9) (step ST1207). Next, peak determining section 111 again determines whether or not the transmission data IFFT after the inverse replica has been synthesized has a peak equal to or greater than X (step ST1208).

 [0058] If transmission data has a peak equal to or greater than threshold value a, subband selecting section 114 newly selects K new subbands (step ST1209). Specifically, as shown in FIG. 13, the subband selection unit 115 selects band 3 in which an MCS having the same transmission efficiency as the MCS of band 2 is selected as a new subband. If the MCS with the same transmission efficiency as the MCS of band 2 is set !, there is no band, and if the transmission efficiency is low next to band 2, the MCS is selected and the band is selected. I do.

 [0059] Then, the wireless communication apparatus repeats the processing of steps ST1205 and ST1208 until there is no peak equal to or greater than threshold value a. In other words, the wireless communication device performs the processing of step ST1205—step ST1209 until all bands within the communication band are selected (until the maximum value of に な る is reached) as long as the peaks equal to or greater than the threshold value α do not disappear. repeat.

 [0060] In step ST1208, if there is no peak equal to or larger than threshold value α, the wireless communication apparatus ends the peak suppression processing.

 [0061] On the other hand, in step ST1203, when there is no peak equal to or larger than threshold α, the wireless communication apparatus ends the peak suppression processing.

 As described above, according to the second embodiment, in addition to the effects of the first embodiment, new bands are successively selected and an inverse replica is synthesized until there are no more peaks equal to or larger than threshold α. Since the band is expanded, it is possible to prevent the error rate characteristic of transmission data of one band from deteriorating.

 (Embodiment 3)

 FIG. 14 and FIG. 15 are flowcharts showing the operation of suppressing the peak of the wireless communication device. Note that the wireless communication apparatus according to Embodiment 3 has the same configuration as in FIG. 1, and a description thereof will be omitted.

 The operation of suppressing the peak of the wireless communication device will be described with reference to FIG.

[0065] First, IFFT section 105 performs an IFFT on the transmission data (step ST1401).

Next, PAPR calculation section 109 measures PAPR (step ST1402).

Next, as shown in FIG. 4, the peak determination unit 111 Based on the value information, it is determined whether or not there is a peak at which the PAPR is greater than or equal to the value (α) (step ST1403).

If PAPR is greater than or equal to threshold α, FFT section 116 performs FFT on the inverse replica (step ST1404).

 Next, combining section 103 combines the transmission signal and the inverse replica in a predetermined communication band (step ST1405).

 [0070] Next, the peak determination unit 111 combines the inverse replica with the transmission signal, and then makes the transmission signal again! It is determined whether there is a peak equal to or greater than the value a (step ST1406).

 [0071] If there is no peak equal to or greater than threshold value a, subband selecting section 114 selects K subbands whose MCS is selected with the highest transmission efficiency (step ST1407). Specifically, the sub-band selecting unit 114 selects one band 1 in which the transmission efficiency is the highest and the MCS is selected in the communication band as shown in FIG.

 Next, sub-band selecting section 114 removes band 1 from all the bands of band 1 and band 3 in the communication band, and selects the remaining bands 2 and 3 (step ST1408).

 Next, sub-band selecting section 114 counts one by one each time a process for selecting a sub-band is performed, and determines whether or not the total count has reached a predetermined number (step ST1409).

 [0074] In a case where the total count has reached the predetermined number, if not, the sub-band selecting unit 114 determines whether or not the peak is detected by the peak determining unit 111, and whether or not the force is applied (step ST1410). .

[0075] In the case where a peak is detected by the peak determination unit 111, if the MCS with the highest transmission efficiency is not used again, the sub-band selection unit 114 selects the remaining sub-bands selected in the communication band. The selected K subbands are selected (step ST1407). More specifically, the sub-band selection unit 114 determines whether the remaining transmission power of the remaining bands 2 and 3 selected in the communication band is the highest, the MCS is selected !, the band 2 or the band 3! , And select one of the K subbands. In the case of FIG. 13, since MCS having the same transmission efficiency is selected for band 2 and band 3, either may be selected. Then, sub-band selection section 114 selects one of the selected band 2 or band 3 and the remaining band 3 or band 2 which has been removed from the selected sub-band (step ST1408). Force to reach the number of times or in step ST1410 Step ST1407—Step ST1410 is repeated until a loop is detected.

[0076] In step ST1410, when a peak is detected by peak determining section 111, subband selecting section 114 returns the K subbands removed immediately before as the subbands to be selected again (step ST1411). ). Specifically, in FIG. 14, when only band 3 is selected in FIG. 14 and band 2 is removed from the selection target immediately before, sub-band selection unit 114 selects band 2 as the selection target band. Return and select band 2 and band 3.

 [0077] Next, FFT section 116 performs FFT on the inverse replica generated by inverse replica generation section 112.

 (Step ST1412).

 Next, combining section 103 combines the transmission signal and the inverse replica subjected to FFT (step ST1413).

 [0079] In step ST1406, when there is a peak equal to or larger than threshold value α, FFT section 116 further performs FFT on the inverse replica (step ST1412), and combines the inverse replica with a transmission signal (step ST1413).

 On the other hand, if the total count has reached the predetermined number in step ST1409, subband selecting section 114 determines that there is no peak equal to or greater than the threshold, and performs peak suppression processing. The processing ends without executing.

[0081] In step ST1403, when there is no peak equal to or larger than threshold α, it is determined that there is no peak equal to or larger than the threshold, and the process ends without performing the peak suppression process.

 As described above, according to the third embodiment, in addition to the effect of the first embodiment, when a peak is not detected after peak suppression and when extra peak suppression is performed, The number of sub-bands to be selected is sequentially reduced until a peak is detected, and when a peak is detected, an inverse replica and a transmission signal are combined. Deterioration of characteristics can be prevented.

 (Embodiment 4)

FIG. 16 is a diagram showing a configuration of a wireless communication apparatus 1600 according to Embodiment 4 of the present invention. Radio communication apparatus 1600 according to Embodiment 4 adds clipping section 1601 to radio communication apparatus 100 according to Embodiment 1 shown in FIG. 1, as shown in FIG. Note that, in FIG. 16, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

 [0085] Clipping section 1601 performs a clipping process on the transmission data input from IFFT section 105, and outputs the result to GI insertion section 106. That is, the clipping unit 1601 compares the threshold value which has been set in advance with the signal level of the transmission data of the transmission data, and if the signal level is equal to or higher than the threshold V, the signal level is increased. Then, the signal is output to GI insertion section 106, and if the signal level is less than the threshold, the transmission data is output to GI insertion section 106 as it is.

 As described above, according to the fourth embodiment, in addition to the effect of the first embodiment, the clipping process is further performed after synthesizing the reverse replay power and the transmission data, so that the peak can be reliably detected. Can be suppressed.

 (Embodiment 5)

 FIG. 17 is a block diagram showing a configuration of radio communication apparatus 1700 according to Embodiment 5 of the present invention.

 [0088] The radio communication apparatus 1700 according to Embodiment 5 is different from the radio communication apparatus 100 according to Embodiment 1 shown in FIG. An SZP conversion section 1701, an IFFT section 1702, and a synthesis section 1703 are provided instead of the SZP conversion section 104 and the IFFT section 105. In FIG. 17, portions having the same configuration as in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

 [0089] SZP conversion section 1701 converts transmission data input from modulation section 102 into a serial data format and a parallel data format, and outputs the result to IFFT section 1702.

 [0090] IFFT section 1702 IFFTs the transmission data input from SZP conversion section 1701 and outputs the result to combining section 1703.

 [0091] Combining section 1703 combines the waveform of the transmission data input from IFFT section 1702 and the inverse replica on the time axis based on the inverse replica information input from BPF 115, and outputs the result to GI insertion section 106.

Next, an operation of suppressing the peak of wireless communication apparatus 1700 will be described with reference to FIG. To do. FIG. 18 is a flowchart showing the operation when suppressing the peak of the wireless communication device 1700.

 First, IFFT section 1702 performs an IFFT on the transmission data (step ST1801).

[0094] Next, PAPR calculation section 109 measures PAPR (step ST1802).

[0095] Next, as shown in Fig. 4, the peak value equal to or greater than the value (α) is determined by the PAPR based on the threshold value input from the cutoff instruction unit 110 and the value information. Is determined (step ST1803).

[0096] If there is a peak whose PAPR is equal to or greater than the threshold value (X, the inverse replica generation unit 112 determines that the amplitude is equal to the threshold value ( j8) Extract waveform information having a value greater than or equal to the threshold! / and a value less than (1β) to generate a replica as shown in FIG. 6 (step ST1804).

[0097] Next, as shown in Fig. 7, inverse replica generating section 112 generates an inverse replica having the inverse characteristic of the generated replica (step ST1805).

[0098] Next, subband selecting section 114 selects the subband specified by subband specifying section 113 (step ST1806), and BPF 115 selects unnecessary subbands other than the frequency band of the subband specified by subband specifying section 113. Outputs the inverse replica excluding the radiation component. Specifically, as shown in FIG. 8, the sub-band selection unit 114 selects MCS6 for transmission data allocated to each sub-carrier in the communication band, modulates the data with 16QAM, and transmits The transmission data allocated to each subcarrier is selected by MCS3 and modulated by QPSK. In this case, if the transmission efficiency is low, MCS is selected, and band 2 is selected.

 [0099] Next, combining section 1703 combines the transmission signal and the inverse replica subjected to IFFT (step ST1807).

 As described above, according to the fifth embodiment, in addition to the effect of the first embodiment, it is not necessary to repeatedly perform the IFFT processing on the entire transmission data, so that the peak suppression processing can be easily performed. can do.

Embodiment 1 The radio communication apparatus according to Embodiment 5 can be applied to a base station apparatus and a communication terminal apparatus. [0102] Each functional block used in the description of each of the above embodiments is typically realized as an LSI that is an integrated circuit. These may be individually made into one chip, or may be made into one chip so as to include a part or all of them.

[0103] Here, depending on the difference in the degree of power integration as an LSI, it may be referred to as an IC, a system LSI, a super LSI, or a general LSI.

[0104] Further, the method of circuit integration is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. Programmable FPGA (Field

Programmable Gate Arrays) or reconfigurable processors that can reconfigure the connections and settings of circuit cells inside the LSI may be used.

Further, if an integrated circuit technology that replaces the LSI appears due to the progress of the semiconductor technology or another technology derived therefrom, naturally, the integration of the functional blocks may be performed using the technology. Biotechnology can be applied.

[0106] The present specification is based on Japanese Patent Application No. 2003-341654 filed on September 30, 2003. All of this content is included here.

 Industrial applicability

The transmitting apparatus and the peak suppressing method according to the present invention have an effect of preventing the deterioration of the error rate characteristic of the entire transmission data by suppressing the peak using a part of the frequencies in the communication band, and reduce the peak. Useful for suppressing.

Claims

The scope of the claims  [1] A transmission device for transmitting a frequency-division multiplexed transmission signal based on reception quality information indicating the reception quality of a communication partner,  Determining means for determining a modulation and coding scheme parameter for each frequency,  Detecting means for detecting a peak in the transmission signal;  Generating means for generating a waveform having an inverse characteristic of the peak waveform;  Synthesizing means for synthesizing the waveform of the inverse characteristic with the waveform of the transmission signal at a frequency corresponding to the modulation and coding scheme parameter having the lowest transmission efficiency among the modulation and coding scheme parameters determined for each frequency;  A transmitting unit that transmits the transmission signal obtained by synthesizing the waveform of the inverse characteristic.  [2] Each time the peak is detected, the apparatus further comprises a selection unit that selects a frequency in ascending order of transmission efficiency of a corresponding modulation and coding scheme parameter,  The combining means combines the waveform of the transmission signal with the waveform of the inverse characteristic at a selected frequency.  The transmitting device according to claim 1. [3] The detecting means comprises:  If a peak is detected in the transmission signal combined with the waveform of the inverse characteristic, and no peak is detected based on the transmission signal combined with the waveform of the inverse characteristic, the corresponding modulation / coding scheme parameter The transmission efficiency of the transmission signal is high! ??????????????????????????????????????????????????????????????????????? Synthesizes waveforms with opposite characteristics,  The transmitting device according to claim 1. [4] The selecting means,  The process of removing the frequency from the frequency within the communication band in the order of higher transmission efficiency of the corresponding modulation and coding scheme parameter is repeated up to a predetermined number of times, The transmitting device according to claim 3. [5] The synthesis means,  2. The transmission device according to claim 1, wherein a waveform of the inverse characteristic is combined with a waveform of the transmission signal on a frequency axis. [6] The apparatus further comprises an inverse orthogonal transform unit for performing an inverse orthogonal transform on the transmission signal,  2. The transmission device according to claim 1, wherein the combining unit combines the inverse orthogonally transformed transmission signal with the waveform having the inverse characteristic. [7] A peak suppression method for suppressing a peak in a frequency division multiplexed transmission signal based on reception quality information indicating a reception quality of a communication partner,  Determining modulation code Eich method parameters for each frequency;  Detecting a peak in the transmitted signal;  Generating a waveform having an inverse characteristic of the waveform of the peak,  Synthesizing the waveform of the inverse characteristic with the waveform of the transmission signal at a frequency corresponding to the modulation / coding scheme parameter having the lowest transmission efficiency among the modulation / coding scheme parameters determined for each frequency;  A peak suppression method comprising: