WO2012060051A1 - Ofdm受信装置、ofdm受信回路、ofdm受信方法、及びofdm受信プログラム - Google Patents
Ofdm受信装置、ofdm受信回路、ofdm受信方法、及びofdm受信プログラム Download PDFInfo
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- WO2012060051A1 WO2012060051A1 PCT/JP2011/005571 JP2011005571W WO2012060051A1 WO 2012060051 A1 WO2012060051 A1 WO 2012060051A1 JP 2011005571 W JP2011005571 W JP 2011005571W WO 2012060051 A1 WO2012060051 A1 WO 2012060051A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2602—Signal structure
- H04L27/2605—Symbol extensions, e.g. Zero Tail, Unique Word [UW]
- H04L27/2607—Cyclic extensions
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2602—Signal structure
- H04L27/261—Details of reference signals
- H04L27/2613—Structure of the reference signals
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2657—Carrier synchronisation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2668—Details of algorithms
- H04L27/2673—Details of algorithms characterised by synchronisation parameters
- H04L27/2675—Pilot or known symbols
Definitions
- the present invention relates to a technique for receiving a signal transmitted by multiplexing a plurality of subcarriers orthogonal to each other.
- the OFDM scheme is a scheme that transmits a plurality of narrowband digitally modulated signals by frequency multiplexing using a plurality of subcarriers orthogonal to each other, and is therefore a transmission scheme with excellent frequency utilization efficiency.
- one symbol period is composed of an effective symbol period and a guard interval period, and a part of the signal of the effective symbol period is copied and inserted into the guard interval period so as to have periodicity within the symbol. . For this reason, it is possible to reduce the influence of inter-symbol interference caused by multipath interference, and it has excellent resistance to multipath interference.
- DVB-T2 Digital Video Broadcasting-Terrestrial
- HD High
- the guard interval of the P1 symbol is different from the guard interval in the conventional ISDB-T (Integrated Services Digital Broadcasting-Terrestrial) and DVB-T.
- a signal for 59 ⁇ s of the first half in the effective symbol period is copied and inserted into a guard interval period (hereinafter referred to as “previous guard interval period”) before the effective symbol period, and the effective symbol period is inserted.
- the signal for the last 53 ⁇ s in the effective symbol section is copied and inserted. Further, when copying and inserting, the copy source signal is frequency-shifted by a predetermined f SH and inserted into the guard interval section (previous guard interval section or rear guard interval section).
- f SH corresponds to one subcarrier interval of the P1 symbol. That is, the signal in the front guard interval and the signal in the rear guard interval have a frequency corresponding to one subcarrier of the P1 symbol higher than the signal in the effective symbol period.
- the entire valid symbol is used for the guard interval.
- the P1 symbol is composed of an Active carrier and a Null carrier (unused carrier).
- FIG. 29 shows the P1 symbol on the frequency axis.
- the transmission format of the P2 symbol or data symbol is MISO (Multiple-Input-Single-Output) or SISO (Single-Input-Single-Output) (hereinafter, “MISO / SISO information”). ), Information on what is the FFT size of the P2 symbol and data symbol (hereinafter referred to as “FFT size information”), and information on whether FEF (Future Extension Frames) is included (hereinafter referred to as “FFT size information”). "FEF presence / absence information”), etc. (hereinafter referred to as "P1 transmission information").
- the FEF is a period for service transmission different from the DVB-T2 in the future, and is inserted between the DVB-T2 frame and the DVB-T2 frame, and there is a P1 symbol at the head of the FEF frame. To do.
- FIG. 30 is a configuration diagram of the P1 generation unit 1000 that generates a P1 symbol.
- P1 symbol generation section 1000 includes series conversion section 1001, differential modulation section 1002, scramble section 1003, CDS table generation section 1004, padding section 1005, IFFT section 1006, and GI addition section 1007.
- P1 transmission information is transmitted by the P1 symbol.
- These pieces of information are represented as a 3-bit S1 signal and a 4-bit S2 signal.
- a 3-bit S1 signal and a 4-bit S2 signal are input to the series conversion unit 1001.
- the sequence conversion unit 1001 holds the conversion table shown in FIG. 31 and converts the 3-bit S1 signal into a 64-bit sequence CSS S1 expressed by the following (Equation 1) using the conversion table.
- the bit S2 signal is converted into a 256-bit series CSS S2 represented by the following (Equation 2).
- sequence conversion section 1001 uses a sequence CSS S1 represented by (Equation 1) and a sequence CSS S2 represented by (Equation 2), and a signal sequence of a total of 384 bits shown in (Equation 3) below.
- MSS_SEQ is configured, and signal sequence MSS_SEQ is output to differential modulation section 1002.
- the signal sequence MSS_SEQ includes two S1 signals having the same content.
- the differential modulation unit 1002 performs differential modulation shown in the following (Equation 4) on the signal sequence MSS_SEQ input from the sequence conversion unit 1001, and the differentially modulated signal sequence MSS_DIFF is sent to the scramble unit 1003. Output.
- the differential modulation performed by the differential modulation unit 1002 is DBPSK (Differential Binary Phase Shift Keying).
- the scrambler 1003 scrambles the differentially modulated signal sequence MSS_DIFF from the differential modulator 1002 as shown in (Equation 7) below, and outputs the scrambled signal sequence MSS_SCR to the padding unit 1005.
- PRBS pseudo random binary sequence
- the scramble shown in (Equation 8) below is performed on i , and the scrambled signal MSS_SCR i is output to the padding section 1005.
- CDS Carrier Distribution Sequence
- Padding section 1005 scrambles the subcarrier at subcarrier position k (i) with the subcarrier at subcarrier position k (i) shown in the CDS table (see FIG. 32) of CDS table generation section 1004 as the active carrier.
- the mapped signal MSS_SCR i is mapped and output to the IFFT unit 1006.
- padding section 1005 outputs subcarriers at subcarrier positions not listed in FIG. 32 as Null carriers to IFFT section 1006.
- the IFFT unit 1006 performs an IFFT (Inverse Fast Fourier Transform) on the output signal of the padding unit 1005 with an FFT size of 1k, and the IFFT result (the signal in the time domain of the effective symbol period in FIG. 28) is a GI addition unit. To 1007.
- IFFT Inverse Fast Fourier Transform
- GI adding section 1007 uses the signal of the effective symbol period input from IFFT section 1006, inserts the signal of the previous part in the effective symbol period in the previous guard interval period after shifting the frequency by f SH , and The signal in the rear part in the effective symbol period is shifted into the guard interval period by f SH and inserted (see FIG. 28). In this way, the P1 symbol is generated.
- the common FFT size and guard interval ratio are used for the P2 symbol and the data symbol.
- the guard interval section in the P2 symbol and the data symbol is provided before the effective symbol section in the same manner as DVB-T and ISDB-T.
- the guard interval section provided before the effective symbol section the signal of the rear part in the effective symbol section is copied and inserted.
- FIG. 33 shows combinations of FFT sizes and guard interval ratios used in DVB-T2, and pilot patterns that can be set by these combinations. There are eight types of pilot patterns from PP1 to PP8. In FIG. 33, “NA” indicates a combination of an FFT size and a guard interval ratio that cannot be set in the standard.
- P2 pilots In the P2 symbol, equally spaced pilots (hereinafter referred to as “P2 pilots”) are inserted.
- P2 pilots When the FFT size is 32k and in the SISO mode, there are P2 pilots every 6 subcarriers, and there are P2 pilots every 3 subcarriers in other cases.
- the P2 symbol includes information on what the pilot pattern of the data symbol is (hereinafter referred to as “pilot pattern information”), information on whether the carrier extension mode is the extended mode or the normal mode (hereinafter referred to as “transmission mode information”). ), The number of symbols per frame, the modulation method, the forward error correction (Forward Error Correction: FEC) code coding rate, and other transmission parameter information necessary for reception (hereinafter referred to as “P2 transmission information”). .)It is included. Note that the number of symbols of the P2 symbol is set as shown in FIG. 34 according to the FFT size of the P2 symbol.
- Non-Patent Document 1 There is a technique disclosed in Non-Patent Document 1 as a P1 symbol demodulation technique in the DVB-T2 transmission format as described above.
- FIG. 35 shows the configuration of the P1 demodulator 2000 that performs demodulation of the P1 symbol.
- the P1 demodulation unit 2000 includes a P1 position detection unit 2001, a P1 narrowband fc error detection correction unit 2002, an FFT unit 2003, a CDS table generation unit 2004, a P1 wideband fc error detection correction unit 2005, and a P1 decoding unit 2006. With.
- the P1 position detection unit 2001 uses the input signal to correlate (guard) the signal in the guard interval section of the P1 symbol (the previous guard interval section and the rear guard interval section) and the signal in a predetermined part of the effective symbol section of the P1 symbol. Correlation) is calculated. Then, the P1 position detection unit 2001 integrates the calculated correlation value with the time width of the guard interval interval (the previous guard interval interval and the subsequent guard interval interval), and detects the peak of the interval integral value to detect the input signal. The position of the P1 symbol at is detected.
- the correlation calculation process is performed in consideration of the frequency shift of fSH added on the transmission side.
- the predetermined portion is a front portion in the effective symbol interval for the previous guard interval interval, and a rear portion in the effective symbol interval for the subsequent guard interval interval (see FIG. 28). .
- the P1 narrowband fc error detection and correction unit 2002 correlates a signal (guard correlation) between a signal in a guard interval section (previous guard interval section and subsequent guard interval section) of the P1 symbol and a signal in a predetermined part of the effective symbol section of the P1 symbol. And a frequency error amount (narrowband carrier frequency error amount) equal to or smaller than the subcarrier interval of the P1 symbol is detected from the correlation. Then, the P1 narrowband fc error detection correction unit 2002 corrects the shift of the narrowband carrier frequency of the P1 symbol based on the detected narrowband carrier frequency error amount, and the P1 symbol in which the shift of the narrowband carrier frequency is corrected Is output to the FFT unit 2003.
- the FFT unit 2003 performs FFT on the time domain signal in the effective symbol period of the P1 symbol with an FFT size of 1k, and the result of the FFT (frequency domain signal in the effective symbol period of the P1 symbol) to the P1 wideband fc error detection and correction unit 2005. Output.
- the CDS table generation unit 2004 generates a sequence indicating the position of the active carrier (hereinafter referred to as “active carrier arrangement sequence”), and outputs the generated arrangement sequence of the active carrier to the P1 wideband fc error detection correction unit 2005.
- active carrier arrangement sequence a sequence in which the positions of the Active carriers shown in FIG. 32 are “1” and the positions of the other Null carriers are “0”.
- the P1 wideband fc error detection / correction unit 2005 uses the active carrier arrangement sequence input from the CDS table generation unit 2004, and uses a frequency error amount (wideband carrier) in the subcarrier interval unit of the P1 symbol in the output signal of the FFT unit 2003. Frequency error amount) is detected. Then, the P1 wideband fc error detection / correction unit 2005 corrects the shift of the wideband carrier frequency of the P1 symbol based on the detected wideband carrier frequency error amount. The P1 wideband fc error detection / correction unit 2005 extracts only the Active carrier from the P1 symbol in which the shift of the wideband carrier frequency is corrected, and outputs the active carrier to the P1 decoding unit 2006.
- the detection of the broadband carrier frequency error amount of the P1 symbol will be described.
- the power of each subcarrier is calculated, and the calculation result is shifted by one subcarrier, and the correlation between the calculation result and the arrangement sequence of known active carriers (input from the CDS table generation unit 2004) ( (Configuration correlation) is calculated.
- the arrangement correlation value at the shift amount at which the wideband carrier frequency error amount becomes zero is the sum of the powers of all active carriers, and includes the null carrier. This value is larger than the correlation value at the shift amount. From this, the shift amount for obtaining the maximum correlation value becomes the broadband carrier frequency error amount, and the broadband carrier frequency error amount can be detected.
- the shift amount is based on the shift amount when there is no wideband carrier frequency error in the input signal (shift amount “0”) (the same applies hereinafter).
- the P1 decoding unit 2006 in FIG. 35 performs P1 symbol decoding processing based on the P1 symbol Active carrier input from the P1 wideband fc error detection and correction unit 2005, and extracts P1 transmission information.
- FIG. 36 is a block diagram of the P1 decoding unit 2006 of FIG.
- the P1 decoding unit 2006 includes a descrambling unit 2101, a differential demodulation unit 2102, and a pattern matching unit 2103.
- the P1 symbol decoding process is performed using only the S1 signal in the low frequency region of the P1 symbol.
- the descrambler 2101 receives the signal sequence Act of the Active carrier from the P1 broadband fc error detection / correction unit 2005 of FIG.
- the descrambling unit 2101 performs descrambling shown in the following (Equation 9) on the signal sequence Act of the active carrier, and outputs the descrambled signal sequence DESCR to the differential demodulation unit 2102.
- the descrambling shown in the following (Equation 10) is performed, and the descrambled signal DESCR i is output to the differential demodulator 2102.
- the superscript “*” represents a conjugate complex (the same applies hereinafter).
- the differential demodulator 2102 performs demodulation (hard decision) of the signal DESCR i ⁇ DESCR * i ⁇ 1 from the polarity of the real axis as a result of the differential detection, and the demodulated signal DEMOD i is used as a pattern matching unit. 2103.
- the processing of the differential demodulation unit 2102 is expressed by the following (Equation 11), and the differential demodulation performed by the differential demodulation unit 2102 is demodulation corresponding to DBPSK.
- the pattern matching unit 2103 converts the signals DEMOD 0 , DEMOD 1 ,..., DEMOD 319 differentially demodulated by the differential demodulation unit 2102 into signal sequences as shown in the following (Equation 12) and (Equation 13). It is divided into DEMOD_CSS S1 (corresponding to S1 signal) and signal sequence DEMOD_CSS S2 (corresponding to S2 signal).
- the index k is used to distinguish the eight series CSS S1 shown in FIG. 31 and also to distinguish the 16 series CSS S2 shown in FIG. 31 (in the following, The same).
- the pattern matching unit 2103 obtains a correlation CORR S1, k between each of the series CSS S1, k and the series DEMOD_CSS S1 in FIG. 31, as shown in the following (Expression 14), and as shown in the following (Expression 15). , The correlation CORR S2, k between each series CSS S2, k and the series DEMOD_CSS S2 in FIG.
- the pattern matching unit 2103 then outputs a 3-bit S1 signal corresponding to the sequence CSS S1, k that takes the maximum correlation value among the eight correlation values calculated using the above (Equation 14) (FIG. 31). Reference) is estimated as the transmitted S1 signal. Also, the pattern matching unit 2103 has a 4-bit S2 signal corresponding to the sequence CSS S2, k that takes the maximum correlation value among the 16 correlation values calculated using the above (Equation 15) (FIG. 31). Reference) is estimated as the transmitted S2 signal. The pattern matching unit 2103 acquires P1 transmission information using the estimated S1 signal and S2 signal.
- the P1 symbol is composed of an Active carrier and a Null carrier (see FIG. 29), and as shown in FIG. 37, the signal in the guard interval section is the signal of the effective symbol section as one subcarrier. Since the frequency is shifted so that the frequency becomes higher (the amount equivalent to the above fSH ), the following problems arise in a noise or multipath interference environment.
- the value described below the frequency axis is the subcarrier number, not the frequency value itself.
- FIG. 38 shows a schematic diagram of a received signal when multipath interference exists.
- the first wave is treated as a main wave and the second wave as a delayed wave.
- the distribution diagram of the subcarriers when FFT is performed on the signal in the effective symbol section of the first wave (main wave) (signal in the effective symbol section of the main wave) is shown in FIG. .
- the signal component of the previous guard interval interval of the delayed wave of the P1 symbol to be subjected to FFT is included. Also, depending on the delay amount of the delayed wave (when the delay amount exceeds the time width of the previous guard interval section), as shown in FIG. 38, the effective symbol of the main wave of the P1 symbol to be FFT-executed is included in the FFT implementation section. In addition to the signal component of the section, the signal component of the previous guard interval section of the delayed wave of the P1 symbol to be subjected to the FFT and the signal component of the previous OFDM symbol (for example, data symbol) are included.
- Each signal in the front guard interval section and the rear guard interval section is obtained by frequency-shifting a part of the signal in the effective symbol section so that the frequency is increased by one subcarrier. Therefore, when there is a delayed wave, the signal component of the active carrier in the previous guard interval section is higher in frequency by one subcarrier than the signal component of the active carrier in the effective symbol section, as shown in FIG. Appears in position. Further, although not shown in FIG. 39, signal components of other OFDM symbols (for example, data symbols) appear in all subcarriers.
- the power of the signal component of the Null carrier is increased, and the arrangement correlation value at the other subcarrier position is compared with the arrangement correlation value at the correct subcarrier position in the arrangement correlation calculation by the P1 wideband fc error detection correction unit 2005.
- the P1 broadband fc error detection / correction unit 2005 erroneously estimates the broadband carrier frequency error amount.
- the estimation of the broadband carrier frequency error amount is similarly erroneous due to the preceding wave.
- the P1 symbol of the DVB-T2 frame is targeted, and the erroneous estimation of the broadband carrier frequency error amount in a multipath interference environment or a noise environment has been described as an issue.
- the erroneous estimation leads to deterioration of the reception performance of the received signal, which is a serious problem on the receiving side.
- An object of the present invention is to provide a receiving apparatus, an OFDM receiving circuit, an OFDM receiving method, and an OFDM receiving program.
- an OFDM receiver of the present invention is an OFDM receiver that receives an OFDM symbol composed of a signal in an effective symbol period and a signal in a guard interval period based on the signal in the effective symbol period.
- a first orthogonal transform unit that orthogonally transforms the signal in the effective symbol period and outputs the result of the orthogonal transform
- a second orthogonal transform unit that orthogonally transforms the signal in the guard interval period and outputs the result of the orthogonal transform
- a correction unit that corrects the shift of the wide band carrier frequency of the OFDM symbol based on the frequency error amount.
- the OFDM receiver described above detection of a wide band carrier frequency error amount of an OFDM symbol is performed using two signals, a signal in an effective symbol period and a signal in a guard interval period based on the signal in the effective symbol period. Therefore, it is possible to reduce erroneous estimation of the broadband carrier frequency error amount of the OFDM symbol even in a multipath interference environment or a severe noise environment, thereby improving reception performance.
- the block diagram of the OFDM receiver A of an example of this invention. 1 is a configuration diagram of an OFDM receiver 1 according to a first embodiment.
- the block diagram of the demodulation part 30 of FIG. The block diagram of the P1 demodulation part 103 of FIG.
- the schematic diagram for demonstrating the signal part of the P1 symbol which P1 orthogonal transformation part 153U and P1 orthogonal transformation part 153G of FIG. 4 implements orthogonal transformation.
- FIG. 5 is a configuration diagram of a P1 broadband fc error detection correction unit 155 of FIG. 4.
- the block diagram of the P1 decoding part 156 of FIG. The schematic diagram in the time-axis of P1 symbol in case a delay wave exists.
- amendment part 400 which concerns on 6th Embodiment.
- the block diagram of the selection determination part 413 of FIG. The block diagram of the P1 wideband fc error detection correction
- the block diagram of the selection determination part 471 of FIG. The block diagram of the P1 wideband fc error detection correction
- amendment part 550 which concerns on 9th Embodiment.
- FIG. 26 is a configuration diagram of the selection determination unit 312A of FIG.
- FIG. FIG. 36 is a configuration diagram of the P1 decoding unit 2006 in FIG. 35.
- a first OFDM receiver that is an aspect of the present invention is an OFDM receiver that receives an OFDM symbol composed of a signal in an effective symbol period and a signal in a guard interval period based on the signal in the effective symbol period.
- a first orthogonal transform unit that orthogonally transforms the signal in the effective symbol period and outputs the result of the orthogonal transform
- a second orthogonal transform unit that orthogonally transforms the signal in the guard interval period and outputs the result of the orthogonal transform
- a detection unit for detecting a broadband carrier frequency error amount of the OFDM symbol based on an output signal of the first orthogonal transform unit and an output signal of the second orthogonal transform unit, and a broadband carrier detected by the detection unit
- a correction unit that corrects the shift of the wide band carrier frequency of the OFDM symbol based on the frequency error amount.
- a first OFDM receiving circuit is an OFDM receiving circuit that receives an OFDM symbol composed of a signal in an effective symbol period and a signal in a guard interval period based on the signal in the effective symbol period.
- a first orthogonal transform circuit that orthogonally transforms the signal in the effective symbol section and outputs the result of the orthogonal transform; and a second orthogonal transform circuit that orthogonally transforms the signal in the guard interval section and outputs the result of the orthogonal transform
- a detection circuit for detecting a broadband carrier frequency error amount of the OFDM symbol based on the output signal of the first orthogonal transform circuit and the output signal of the second orthogonal transform circuit, and the broadband carrier detected by the detection circuit
- a correction circuit that corrects a shift in the broadband carrier frequency of the OFDM symbol based on a frequency error amount. That.
- a first OFDM receiving method is performed in an OFDM receiving apparatus that receives an OFDM symbol composed of a signal in an effective symbol period and a signal in a guard interval period based on the signal in the effective symbol period.
- a first orthogonal transform step for orthogonally transforming the signal in the effective symbol interval a second orthogonal transform step for orthogonally transforming the signal in the guard interval interval, and the first orthogonal transform step Based on the result of orthogonal transform and the result of orthogonal transform in the second orthogonal transform step, a detection step for detecting the broadband carrier frequency error amount of the OFDM symbol, and the broadband carrier frequency error amount detected in the detection step Based on the wideband carrier frequency correction of the OFDM symbol based on Includes a correction step that, a.
- a first OFDM reception program provides an OFDM receiver that receives an OFDM symbol composed of a signal in an effective symbol period and a signal in a guard interval period based on the signal in the effective symbol period.
- a first orthogonal transform step for orthogonally transforming the signal in the effective symbol period, a second orthogonal transform step for orthogonally transforming the signal in the guard interval period, a result of the orthogonal transform in the first orthogonal transform step, and the second A detection step of detecting a wide band carrier frequency error amount of the OFDM symbol based on an orthogonal transformation result in the orthogonal transformation step, and a wide band carrier of the OFDM symbol based on the wide band carrier frequency error amount detected in the detection step And a correction step for correcting the frequency shift.
- each of the above-described OFDM receiver, OFDM receiver circuit, OFDM reception method, and OFDM reception program two signals are used: a signal in an effective symbol period and a signal in a guard interval period based on the signal in the effective symbol period.
- a signal in an effective symbol period and a signal in a guard interval period based on the signal in the effective symbol period.
- FIG. 1 receives an OFDM symbol composed of a signal in an effective symbol period and a signal in a guard interval period based on the signal in the effective symbol period.
- the first orthogonal transform unit A1 which corresponds to the first orthogonal transform unit of the first OFDM receiver, orthogonally transforms the signal in the effective symbol period and outputs the result of the orthogonal transform.
- the second orthogonal transform unit A2 corresponds to the second orthogonal transform unit of the first OFDM receiving apparatus, performs orthogonal transform on the signal in the guard interval section, and outputs the result of the orthogonal transform.
- the detection unit A3 corresponds to the detection unit of the first OFDM receiver, and calculates the wide band carrier frequency error amount of the OFDM symbol based on the output signal of the first orthogonal transform unit A1 and the output signal of the second orthogonal transform unit A2.
- the correction unit A4 corresponds to the correction unit of the first OFDM receiver, and corrects the shift of the wide band carrier frequency of the OFDM symbol based on the wide band carrier frequency error amount detected by the detection unit A3.
- the second OFDM receiver according to an aspect of the present invention is the first OFDM receiver, wherein the signal in the guard interval section is obtained by frequency-shifting the signal in the effective symbol section.
- the signal in the guard interval section is obtained by frequency-shifting the signal in the effective symbol section, the same signal is transmitted at two different frequencies (transmitted with two different transmission path characteristics), and both signals Is used to detect a wide band carrier frequency error amount of an OFDM symbol. For this reason, erroneous detection of the broadband carrier frequency error amount can be reduced under a severe noise environment or a multipath interference environment, and stable reception is possible.
- a third OFDM receiver cancels the frequency shift with respect to an input signal of the second orthogonal transform unit or an output signal of the second orthogonal transform unit in the second OFDM receiver.
- a frequency shift correction unit that performs a correction process related to the implementation of the frequency shift in the reverse direction before or after the second orthogonal transform unit and outputs a result of the correction process, and the detection unit includes the broadband carrier
- the correction of the frequency shift is performed by orthogonally transforming the output signal of the first orthogonal transform unit and the output signal of the frequency shift correction unit, or the output signal of the second orthogonal transform unit obtained by orthogonal transform Based on the output signal.
- the signal in the guard interval section is a frequency shift of the signal in the effective symbol section, and in a noisy environment or a multipath interference environment. It is possible to reduce erroneous detection of the wideband carrier frequency error amount, and stable reception becomes possible.
- the OFDM symbol is a P1 symbol in a DVB-T2 transmission scheme
- the guard interval period is greater than the effective symbol period. It consists of a front guard interval section in front and a rear guard interval section after the effective symbol section, and the second orthogonal transform unit performs the orthogonal transform on the signal of the previous guard interval section and the rear guard interval section.
- the signal is combined with the signal.
- the plurality of subcarriers constituting the OFDM symbol are composed of a plurality of Active carriers and a plurality of Null carriers.
- the subcarrier position where each of the plurality of Active carriers is arranged is defined by a predetermined arrangement pattern, and the detection unit outputs the output signal of the first orthogonal transformation unit and the output of the second orthogonal transformation unit And adding the value of the signal in the subcarrier corresponding to the position of the plurality of active carriers defined by the arrangement pattern in the plurality of consecutive subcarriers of the signal based on the signal, This is done by sequentially shifting the carrier within the predetermined range in the subcarrier direction in units of one subcarrier. Based on the result of the processing to detect the broadband carrier frequency error amount.
- the detection of the broadband carrier frequency error amount of the OFDM symbol is performed using the signal of the effective symbol period and the signal of the guard interval period, the multipath interference environment or the environment with severe noise is detected. Even in the lower case, it is possible to reduce erroneous estimation of the broadband carrier frequency error amount of the OFDM symbol, and to improve the reception performance.
- the detection unit is configured to calculate a complex between an output signal of the first orthogonal transform unit and an output signal of the second orthogonal transform unit.
- a complex multiplication unit that performs multiplication for each subcarrier, and an addition process for adding complex multiplication values in subcarriers corresponding to the positions of a plurality of active carriers defined by the arrangement pattern in a plurality of consecutive subcarriers,
- An addition processing unit that outputs the result of the addition processing by sequentially shifting the plurality of consecutive subcarriers in a subcarrier direction within a predetermined range in units of one subcarrier, and each output signal of the addition processing unit Calculating a power and outputting a calculation result; and detecting a maximum value from each output signal of the power calculation unit to detect the wideband carrier frequency error. It includes a maximum value detector for detecting the amount of a.
- the detection unit calculates the power of the output signal of the first orthogonal transform unit for each subcarrier, and calculates the calculation result.
- a first power calculation unit that outputs, a second power calculation unit that calculates power of an output signal of the second orthogonal transform unit for each subcarrier, and outputs a calculation result; and an output signal of the first power calculation unit;
- a multiplication unit that performs multiplication with the output signal of the second power calculation unit for each subcarrier, and a plurality of consecutive subcarriers at subcarriers corresponding to the positions of the plurality of Active carriers defined by the arrangement pattern.
- the addition process for adding the multiplication values is performed while sequentially shifting the plurality of consecutive subcarriers in the subcarrier direction in the subcarrier direction within a predetermined range, and the result of the addition process is output. That includes an addition unit, and a maximum value detector for detecting the wide band carrier frequency error amount by detecting a maximum value from among the output signal of the adding unit.
- An eighth OFDM receiver is the fifth OFDM receiver, wherein the detection unit calculates an amplitude of an output signal of the first orthogonal transform unit for each subcarrier, and calculates a calculation result.
- a first amplitude calculator for outputting, an amplitude of an output signal of the second orthogonal transform unit for each subcarrier, a second amplitude calculator for outputting a calculation result, and an output signal of the first amplitude calculator
- a multiplication unit that performs multiplication with the output signal of the second amplitude calculation unit for each subcarrier, and a plurality of continuous subcarriers in subcarriers corresponding to the positions of the plurality of Active carriers defined by the arrangement pattern.
- the addition process for adding the multiplication values is performed while sequentially shifting the plurality of consecutive subcarriers in the subcarrier direction in the subcarrier direction within a predetermined range, and the result of the addition process is output. That includes an addition unit, and a maximum value detector for detecting the wide band carrier frequency error amount by detecting a maximum value from among the output signal of the adding unit.
- the plurality of subcarriers constituting the OFDM symbol are configured by a plurality of Active carriers and a plurality of Null carriers.
- the subcarrier position where each of the plurality of Active carriers is arranged is defined by a predetermined arrangement pattern, and the detection unit outputs the output signal of the first orthogonal transformation unit and the output of the second orthogonal transformation unit First detection processing for detecting a first candidate of a wideband carrier frequency error amount using both of the signal and detecting the reliability of the first candidate, an output signal of the first orthogonal transform unit, and the second orthogonal transform
- the second candidate of the wideband carrier frequency error amount is detected using only the output signal of the first orthogonal transform unit among the output signals of the unit, and the reliability of the second candidate is determined.
- the second detection processing to be output, and only the output signal of the second orthogonal transform unit out of the output signal of the first orthogonal transform unit and the output signal of the second orthogonal transform unit is used to calculate the wideband carrier frequency error amount.
- the wideband carrier frequency error amount candidate having the highest reliability is performed by the correction unit using at least two of a third detection process for detecting a third candidate and detecting the reliability of the third candidate. Select as carrier frequency error amount.
- the detection unit performs the first detection processing on the output signal of the first orthogonal transform unit and the second orthogonal transform.
- Addition processing for adding the values of the first signals in the subcarriers corresponding to the positions of the plurality of active carriers defined by the arrangement pattern in the plurality of consecutive subcarriers of the first signal based on the output signal of the first part The successive subcarriers are sequentially shifted in the subcarrier direction by one subcarrier within a predetermined range, and the first candidate of the wideband carrier frequency error amount and the first
- the second detection process is performed by detecting the reliability of one candidate, and the second detection process is performed on a plurality of consecutive subkeys of the second signal based on the output signal of the first orthogonal transform unit.
- an addition process of adding the values of the second signals in the subcarriers corresponding to the positions of the plurality of active carriers defined by the arrangement pattern is performed, and the consecutive subcarriers are subcarriers within a predetermined range.
- the third candidate is performed by sequentially shifting the subcarrier in the direction, and detecting the second candidate of the wideband carrier frequency error amount and the reliability of the second candidate based on the result of the addition process, In the detection process, the third signal in the subcarrier corresponding to the position of the plurality of active carriers defined by the arrangement pattern in the plurality of consecutive subcarriers of the third signal based on the output signal of the second orthogonal transform unit
- the subcarriers in the subcarrier direction within a predetermined range are added to the subcarriers within a predetermined range. Performed while successively shifting the unit is carried out by detecting the reliability of the third candidate and the third candidate of the wide band carrier frequency error amount based on the result of the addition process.
- each of the first to third reliability values is obtained by dividing the maximum value of the result of the addition process by the second largest value.
- each of the first to third reliability values is a maximum value of the result of the addition processing, and the higher the value, the more reliable the reliability. High degree.
- each of the first to third reliability values includes a maximum value and a second largest value as a result of the addition process. The greater the difference, the higher the reliability.
- a fourteenth OFDM receiving apparatus is the tenth OFDM receiving apparatus, wherein the effective symbol interval signal and the guard interval interval signal are based on the detected reliability of each candidate.
- a selection unit that selects one of them and outputs the selected signal to the correction unit is further included, and the correction unit corrects the wideband carrier frequency shift with respect to the signal input from the selection unit.
- wideband carrier frequency shift correction is performed on the signal having the higher reliability among the signal in the effective symbol section and the signal in the guard interval section, so that the reception performance can be improved.
- an OFDM receiver 1 according to a first embodiment of the present invention will be described with reference to the drawings.
- an OFDM receiver that operates as a digital broadcast receiver compliant with the DVB-T2 system which is the second generation European terrestrial digital broadcast standard, is taken as an example.
- the received signal received by the OFDM receiver 1 is an OFDM signal composed of OFDM symbols conforming to the DVB-T2 transmission format.
- FIG. 2 is a configuration diagram of the OFDM receiver 1 according to the first embodiment.
- the OFDM receiver 1 includes an antenna 10, a tuner 20, a demodulation unit 30, a decoding unit 40, and a display unit 50.
- the antenna 10 receives a broadcast wave emitted from a broadcast station (not shown), and outputs the received broadcast wave to the tuner 20.
- the tuner 20 selects a reception signal of a desired reception channel from a plurality of broadcast waves input from the antenna 10, converts the selected reception signal from an RF (Radio Frequency) band to an IF (Intermediate Frequency) band,
- the IF band received signal is output to demodulator 30.
- the demodulator 30 demodulates the received signal input from the tuner 20 and outputs a signal obtained as a result of the demodulation to the decoder 40, as will be described in detail later.
- the decoding unit 40 is a signal input from the demodulating unit 30, for example, H.264.
- a signal compressed by H.264 or the like is decoded into a video signal or an audio signal, and the decoded video signal or audio signal is output to the display unit 50.
- the display unit 50 performs video display based on the video signal input from the decoding unit 40 and performs audio output based on the audio signal input from the decoding unit 40.
- FIG. 3 is a block diagram of the demodulator 30 of FIG.
- the demodulation unit 30 includes an A / D conversion unit 60, a demodulation core unit 70, and a control information collection unit 80.
- the IF band received signal is input to the A / D converter 60 from the tuner 20 of FIG.
- the A / D converter 60 converts the received signal input from the tuner 20 from an analog signal to a digital signal, and the received signal converted to a digital signal (hereinafter referred to as “digital received signal”) is a demodulation core unit.
- digital received signal is a demodulation core unit.
- the data is output to a quadrature demodulator 101 described later.
- the demodulation core unit 70 includes an orthogonal demodulation unit 101, an fc correction unit 102, a P1 demodulation unit 103, a GI determination unit 104, a narrowband fc error calculation unit 105, an orthogonal transformation unit 106, and a wideband fc error calculation unit. 107, a transmission path characteristic estimation unit 108, an equalization unit 109, and an error correction unit 110.
- Each unit in the demodulation core unit 70 operates using the control information collected by the control information collection unit 80 as necessary.
- the quadrature demodulation unit 101 performs quadrature demodulation on the IF band digital reception signal input from the A / D conversion unit 60 with a fixed frequency, and includes a complex baseband signal (consisting of an in-phase component and a quadrature component) obtained as a result of the quadrature demodulation. Signal) to the fc correction unit 102.
- the fc correction unit 102 has been calculated by the narrowband fc error calculation unit 105 until now, which has been detected by the narrowband carrier frequency error amount (described later) and the wideband carrier frequency error amount (described later) detected by the P1 demodulation unit 103.
- the corrected carrier frequency is generated based on the narrow-band carrier frequency error amount (described later) and the wide-band carrier frequency error amount (described later) calculated by the wide-band fc error calculation unit 107 so far.
- the fc correction unit 102 corrects the carrier frequency shift of the complex baseband signal input from the orthogonal demodulation unit 101 based on the corrected carrier frequency, and the complex baseband signal with the corrected carrier frequency shift is corrected to the P1 demodulation unit. 103, the GI determination unit 104, the narrowband fc error calculation unit 105, and the orthogonal transform unit 106.
- the quadrature demodulation unit 101 performs quadrature demodulation using a fixed frequency, and the fc correction unit 102 corrects the carrier frequency shift.
- the present invention is not limited to this. It may be.
- the quadrature demodulator that simultaneously corrects the carrier frequency deviation performs quadrature demodulation using a frequency obtained by adding the fixed frequency and the detected carrier frequency error amount to correct the carrier frequency deviation. A signal may be obtained.
- the complex baseband signal in which the shift of the carrier frequency is corrected is input from the fc correction unit 102 to the P1 demodulation unit 103.
- the P1 demodulator 103 detects a P1 symbol included in the DVB-T2 frame from the input complex baseband signal.
- the P1 demodulator 103 detects, from the P1 symbol, a frequency error amount (narrowband carrier frequency error amount) within the subcarrier interval of the P1 symbol and a frequency error amount (wideband carrier frequency error amount) in the subcarrier interval of the P1 symbol. Then, the deviation of the carrier frequency of the P1 symbol is corrected based on them.
- the P1 demodulating unit 103 performs a decoding process of the P1 symbol in which the deviation of the carrier frequency is corrected, and the P1 transmission information (FFT size information, MISO / SISO information, FEF presence / absence information, etc.) transmitted with the P1 symbol.
- the information is output to the control information collecting unit 80 as control information.
- the P1 demodulating unit 103 outputs the detected narrow band carrier frequency error amount and wide band carrier frequency error amount to the fc correction unit 102. Details of the P1 demodulator 103 will be described later with reference to FIG.
- the GI determination unit 104 receives information (FFT size information) from the control information collection unit 80 regarding the FFT size of the P2 symbol and data symbol transmitted by the P1 symbol. Based on the received FFT size at each guard interval ratio specified by DVB-T2, the GI determination unit 104 uses the guard interval interval signal and the effective symbol in the P2 symbol or data symbol input from the fc correction unit 102 The correlation (guard correlation) with the signal at the back of the section is calculated. The GI determination unit 104 estimates the guard interval ratio of the P2 symbol and the data symbol used for actual transmission based on the calculation result of the guard correlation, and uses the estimated guard interval ratio as control information. Output to 80.
- FFT size information information from the control information collection unit 80 regarding the FFT size of the P2 symbol and data symbol transmitted by the P1 symbol. Based on the received FFT size at each guard interval ratio specified by DVB-T2, the GI determination unit 104 uses the guard interval interval signal and the effective symbol in the P2 symbol or data symbol input from the fc correction unit
- the narrowband fc error calculation unit 105 receives the FFT sizes of the P2 symbol and the data symbol and their guard interval ratios from the control information collection unit 80. Then, the narrowband fc error calculation unit 105 uses the FFT size and the guard interval ratio, and the signal in the guard interval section and the signal in the rear part of the effective symbol section in the P2 symbol and the data symbol input from the fc correction unit 102 (Guard correlation) is calculated. Then, the narrowband fc error calculation unit 105 calculates a frequency error amount (narrowband carrier frequency error amount) within the subcarrier interval between the P2 symbol and the data symbol based on the calculated guard correlation, and calculates the calculated narrowband carrier. The frequency error amount is output to the fc correction unit 102.
- a frequency error amount narrowband carrier frequency error amount
- the orthogonal transform unit 106 performs orthogonal transform on the signal (time domain complex baseband signal) in the effective symbol period of the P2 symbol and the data symbol input from the fc correction unit 102, and results of the orthogonal transform (complex baseband in the frequency domain). Signal) to the wideband fc error calculation unit 107, the transmission path characteristic estimation unit 108, and the equalization unit 109. Note that the orthogonal transform unit 106 performs orthogonal transform based on Fourier transform, cosine transform, wavelet transform, Hadamard transform, and the like.
- the orthogonal transform unit 106 performs orthogonal transform using Fourier transform, and uses FFT for Fourier transform.
- the orthogonal transform unit 106 performs FFT on the signal in the effective symbol period (time domain complex baseband signal) of the P2 symbol and the data symbol, and uses the FFT result (frequency domain complex baseband signal) as a wideband fc error.
- the data is output to the calculation unit 107, the transmission path characteristic estimation unit 108, and the equalization unit 109. Note that the processing of the orthogonal transform unit 106 is not limited to this.
- Wideband fc error calculation section 107 uses the complex baseband signal (signal related to P2 symbol and data symbol) in the frequency domain input from orthogonal transform section 106 to calculate the correlation of the arrangement sequence of pilot signals included therein. Then, the wideband fc error calculation unit 107 calculates a frequency error amount (wideband carrier frequency error amount) in subcarrier interval units of the P2 symbol and the data symbol using the correlation calculation result, and calculates the calculated wideband carrier frequency error. The amount is output to the fc correction unit 102.
- a wideband fc correction unit is provided between the orthogonal transform unit 106, the transmission path characteristic estimation unit 108, and the equalization unit 109.
- the wideband fc error calculation unit 107 outputs the calculated wideband carrier frequency error amount to the fc correction unit 102.
- the wideband fc correction unit corrects the shift of the wideband carrier frequency of the P2 symbol and the data symbol input from the orthogonal transform unit 106 using the wideband carrier frequency error amount calculated by the wideband fc error calculation unit 107, and The P2 symbol and the data symbol whose frequency deviation is corrected are output to the transmission path characteristic estimation unit 108 and the equalization unit 109.
- the transmission path characteristic estimator 108 receives the frequency domain complex baseband signals (signals related to P2 symbols and data symbols) from the orthogonal transformer 106.
- the transmission path characteristic estimation unit 108 estimates the amplitude and phase distortion characteristics (transmission path characteristics) received by the input complex baseband signal in the frequency domain in the transmission path by using a pilot signal included therein, The estimated transmission path characteristics are output to the equalization unit 109.
- the equalization unit 109 receives a frequency domain complex baseband signal (a signal related to P2 symbols and data symbols) from the orthogonal transform unit 106.
- the equalization unit 109 corrects amplitude and phase distortion of the input complex baseband signal in the frequency domain using the transmission path characteristics estimated by the transmission path characteristic estimation unit 108. Then, equalization section 109 outputs a signal with corrected amplitude and phase distortion to error correction section 110.
- the error correction unit 110 performs error correction processing on the signal with corrected amplitude and phase distortion input from the equalization unit 109, and outputs a stream such as a transport stream to the decoding unit 40 in FIG.
- the P2 transmission information (pilot pattern information, transmission mode information, number of symbols per frame, modulation method, FEC code coding rate, etc.) transmitted in the P2 symbol is output to the control information collecting unit 80 as control information.
- the control information collection unit 80 classifies the transmission parameters from the control information collected from the P1 demodulation unit 103, the GI determination unit 104, and the error correction unit 110, and outputs the transmission parameters to each unit in the demodulation core unit 70. Each unit in the demodulation core unit 70 operates using the control information collected by the control information collection unit 80 as necessary.
- the P1 demodulating unit 103 in the demodulating unit 30 among the units described in FIG. 2 and FIG.
- FIG. 4 is a block diagram of the P1 demodulator 103 of FIG.
- the P1 demodulation unit 103 includes a P1 position detection unit 151, a P1 narrowband fc error detection correction unit 152, a P1 orthogonal transform unit 153U, a P1 orthogonal transform unit 153G, a CDS table generation unit 154, and a P1 wideband fc error detection.
- a correction unit 155 and a P1 decoding unit 156 are provided.
- the P1 position detection unit 151 receives the output signal (the complex baseband signal in the time domain) of the fc correction unit 102 in FIG.
- the P1 position detection unit 151 uses the input time domain complex baseband signal to perform a predetermined interval between a P1 symbol guard interval period (previous guard interval period and rear guard interval period) and a P1 symbol effective symbol period.
- the correlation (guard correlation) with the partial signal is calculated.
- the P1 position detection unit 151 inputs the calculated correlation value by integrating the calculated correlation value with the time interval of the guard interval interval (the previous guard interval interval and the subsequent guard interval interval) and detecting the peak of the interval integration value.
- the position of the P1 symbol in the complex baseband signal is detected.
- the correlation calculation process is performed in consideration of the frequency shift of fSH added on the transmission side.
- the predetermined portion is a front portion in the effective symbol interval for the previous guard interval interval, and a rear portion in the effective symbol interval for the subsequent guard interval interval (see FIG. 28). The same applies to correlation calculation processing by the P1 narrowband fc error detection correction unit 152 described later.
- the P1 narrowband fc error detection / correction unit 152 calculates a correlation (guard correlation) between a signal in the guard interval section (the previous guard interval section and the rear guard interval section) of the P1 symbol and a signal in a predetermined part of the effective symbol section. To go. Then, the P1 narrowband fc error detection and correction unit 152 integrates the calculated correlation value with the time width of the guard interval interval (the previous guard interval interval and the subsequent guard interval interval), and calculates the phase of the interval integration value. To go.
- a correlation guard correlation
- the P1 narrowband fc error detection correction unit 152 is configured to detect a frequency error amount (narrowband carrier frequency within the P1 symbol subcarrier interval based on the phase value at the timing of the position of the P1 symbol detected by the P1 position detection unit 151. Error amount) is detected.
- the P1 narrowband fc error detection correction unit 152 corrects the narrowband carrier frequency shift of the P1 symbol based on the detected narrowband carrier frequency error amount, and the P1 symbol with the narrowband carrier frequency shift corrected is P1.
- the P1 orthogonal transform unit 153U receives the output signal of the P1 narrowband fc error detection correction unit 152 (P1 symbol time domain complex baseband signal). As illustrated in FIG. 5, the P1 orthogonal transform unit 153U cuts out a signal in the effective symbol period (the signal of the effective symbol (A) in FIG. 5) from the P1 symbol, and extracts the signal in the extracted effective symbol period (a complex base in the time domain). Band signal) is orthogonally transformed, and the result of the orthogonal transformation (frequency domain complex baseband signal) is output to the P1 wideband fc error detection and correction unit 155. Note that the P1 orthogonal transform unit 153U performs orthogonal transform based on Fourier transform, cosine transform, wavelet transform, Hadamard transform, and the like.
- the P1 orthogonal transform unit 153U performs orthogonal transform using Fourier transform, and uses FFT for Fourier transform.
- the P1 orthogonal transform unit 153U performs FFT on the signal in the effective symbol period of the P1 symbol (time domain complex baseband signal) with an FFT size of 1k, and the result of the FFT (frequency domain complex baseband signal) is P1.
- Output to wideband fc error detection and correction unit 155 Note that the processing of the P1 orthogonal transform unit 153U is not limited to this.
- a signal in an effective symbol section in which the P1 orthogonal transform unit 153U cuts out from the output signal of the P1 narrowband fc error detection correction unit 152 and performs orthogonal transform includes a P1 symbol subject to orthogonal transform in a multipath interference environment or the like.
- the signal component of the preceding guard interval period of the preceding wave of the P1 symbol to be orthogonally transformed or the preceding guard interval period of the delayed wave may be included.
- the signal component of an OFDM symbol (eg, data symbol) may be included.
- a noise component is included in a signal in an effective symbol section in which the P1 orthogonal transform unit 153U cuts out from the output signal of the P1 narrowband fc error detection correction unit 152 and performs orthogonal transform in a noise environment or the like.
- the output signal (complex baseband signal in the time domain of P1 symbol) of the P1 narrowband fc error detection correction unit 152 is input to the P1 orthogonal transform unit 153G.
- the P1 orthogonal transform unit 153G performs a signal from the P1 symbol in the previous guard interval section (a signal in the guard interval (C) in FIG. 5) and a signal in the rear guard interval section (the guard interval (B in FIG. 5)). ))) And combine them so as to be continuous in time.
- a section obtained by combining the front guard interval section and the rear guard interval section is referred to as a “combined guard interval section”.
- the P1 orthogonal transform unit 153G orthogonally transforms the signal (complex baseband signal in the time domain) in the combined guard interval section, and the result of the orthogonal transform (complex baseband signal in the frequency domain) is a P1 wideband fc error detection correction unit.
- the P1 orthogonal transform unit 153G performs orthogonal transform based on Fourier transform, cosine transform, wavelet transform, Hadamard transform, and the like.
- the P1 orthogonal transform unit 153G performs orthogonal transform using Fourier transform, and uses FFT for Fourier transform.
- the P1 orthogonal transform unit 153G performs FFT on the signal (complex baseband signal in the time domain) in the combined guard interval section with an FFT size of 1k, and the result of the FFT (complex baseband signal in the frequency domain) is P1 wideband fc.
- the data is output to the error detection correction unit 155. Note that the processing of the P1 orthogonal transform unit 153G is not limited to this.
- the signal in the combined guard interval section that the P1 orthogonal transform unit 153G cuts out from the output signal of the P1 narrowband fc error detection correction unit 152 and performs orthogonal transform includes the main guard joint interval section of the P1 symbol to be orthogonally transformed.
- a signal component of an effective symbol period of the preceding wave or delayed wave of the P1 symbol to be orthogonally transformed may be included, and further, a signal component of another OFDM symbol (for example, a data symbol) is included.
- a signal component of another OFDM symbol for example, a data symbol
- a noise component is included in a signal in the combined guard interval section in which the P1 orthogonal transform unit 153G cuts out from the output signal of the P1 narrowband fc error detection correction unit 152 and performs orthogonal transform in a noise environment or the like.
- the CDS table generation unit 154 generates a sequence indicating the position of the active carrier (active carrier arrangement sequence), and outputs the generated active carrier arrangement sequence to the P1 wideband fc error detection correction unit 155.
- the arrangement sequence of the Active carrier is a sequence in which the position of the Active carrier illustrated in FIG. 32 is “1” and the positions of the other null carriers (unused carriers) are “0”.
- the CDS table generation unit 154 may hold, for example, a table having the contents shown in FIG. 32 in advance, and may generate an arrangement sequence of Active carriers based on the table, or may be configured with a logic circuit. Then, an arrangement sequence of Active carriers may be generated. Note that the method for generating an arrangement sequence of Active carriers by the CDS table generating unit 154 is not particularly limited.
- the P1 wideband fc error detection correction unit 155 outputs the output signal of the P1 orthogonal transform unit 153U (complex baseband signal in the frequency domain of the effective symbol period of the P1 symbol) and the output signal of the P1 orthogonal transform unit 153G (the combined guard interval of the P1 symbol)
- the frequency error amount (wideband carrier frequency error amount) of the subcarrier interval unit of the P1 symbol using the complex baseband signal in the frequency domain of the interval) and the active carrier arrangement sequence input from the CDS table generation unit 154 To detect.
- the P1 wideband fc error detection correction unit 155 corrects the wideband carrier frequency shift of the P1 symbol based on the detected wideband carrier frequency error amount, and only the active carrier from the P1 symbol in which the wideband carrier frequency shift is corrected. Is extracted and output to the P1 decoding unit 156.
- the P1 broadband fc error detection / correction unit 155 outputs the detected broadband carrier frequency error amount to the fc correction unit 102 of FIG. Details of the P1 broadband fc error detection correction unit 155 will be described later with reference to FIG.
- the P1 decoding unit 156 performs P1 symbol decoding processing using the P1 symbol Active carrier input from the P1 wideband fc error detection correction unit 155, and uses the P1 transmission information transmitted by the P1 symbol as control information. 3 is output to the control information collecting unit 80. Details of the P1 decoding unit 156 will be described later with reference to FIG.
- FIG. 6 is a block diagram of the P1 broadband fc error detection correction unit 155 of FIG. 6 also illustrates a P1 orthogonal transform unit 153U, a P1 orthogonal transform unit 153G, and a CDS table generation unit 154 in order to clarify the input to each unit of the P1 wideband fc error detection correction unit 155.
- the P1 broadband fc error detection correction unit 155 includes a detection unit 170 and a correction unit 180.
- the detection unit 170 detects a frequency error amount (wideband carrier frequency error amount) in the P1 symbol subcarrier interval unit in the P1 symbol, and includes a complex multiplication unit 171 and an arrangement correlation calculation unit (addition processing unit). 172, a power calculation unit 173, and a maximum value detection unit 174.
- the complex multiplier 171 includes an output signal from the P1 orthogonal transform unit 153U (complex baseband signal in the frequency domain of the effective symbol period of the P1 symbol) and an output signal of the P1 orthogonal transform unit 153G (in the combined guard interval period of the P1 symbol). Frequency domain complex baseband signal). For each subcarrier, the complex multiplier 171 outputs the output signal Y U (n) of the P1 orthogonal transform unit 153U and the output signal Y G (n + 1) of the P1 orthogonal transform unit 153G, as shown in (Equation 16) below.
- the complex multiplication result Y COMB (n) is output to the arrangement correlation calculation unit 172.
- the variable in () of Y U (n), Y G (n + 1), and Y COMB (n) represents a subcarrier number (hereinafter the same).
- the complex multiplier 171 instead of the calculation of the above equation (16), the signal of the complex conjugate of the output signal Y U (n) Y U ( n) * and the output signal Y G (n + 1) and multiplying the The multiplication result Y U (n) * ⁇ Y G (n + 1) may be output to the arrangement correlation calculation unit 172.
- a prior signal of the signal and the rear guard interval of the guard interval section is that the signal of the effective symbol section and a frequency shifted by f SH (one obtained by frequency shifting as subcarriers frequency is increased).
- the output signal of the P1 orthogonal transform unit 153G is shifted to the high frequency side by one subcarrier with respect to the output signal of the P1 orthogonal transform unit 153U.
- the output signal Y U (n) of the P1 orthogonal transform unit 153U and the output signal Y G (n + 1) of the P1 orthogonal transform unit 153G having a frequency higher by one subcarrier than that are complex-multiplied.
- Arrangement correlation calculation section 172 receives an arrangement sequence of Active carriers from CDS table generation section 154 and an output signal of complex multiplication section 171. Arrangement correlation calculation section 172 performs a plurality of consecutive addition processes for adding the value of the output signal of complex multiplication section 171 in the subcarrier whose active carrier arrangement sequence value is “1” in the plurality of consecutive subcarriers. The subcarriers are sequentially shifted in the subcarrier direction within a predetermined range in units of one subcarrier (the arrangement correlation calculation unit 172 calculates the arrangement correlation between the output signal of the complex multiplication unit 171 and the arrangement sequence of the active carriers.
- the arrangement correlation calculation unit 172 sequentially outputs the addition value (position correlation value) obtained as a result of the addition process to the power calculation unit 173.
- the arrangement correlation calculation unit 172 outputs the output signals Y COMB (0 + A + i), Y COMB (1 + A + i), Y COMB (2 + A + i),..., Y COMB (852 + A + i) of the complex multiplication unit 171 and the CDS table
- the output signal C (0), C (1), C (2),..., C (852) of the generation unit 154 is multiplied, and the multiplication result is added, and the calculation result C (0) XY COMB (0 + A + i) + C (1) ⁇ Y COMB (1 + A + i) + C (2) ⁇ Y COMB (2 + A + i) +... + C (852) ⁇ Y COMB (852 + A + i) is output to the power calculation unit 173.
- C (i) is the value of the arrangement sequence of Active carriers at subcarrier position i (“1” when subcarrier position i is an Active carrier, “0” when Null carrier is used) (see FIG. 32).
- Y COMB (j) is the value of the subcarrier number j of the output signal of the complex multiplier 171.
- “852” is a value based on the arrangement of the Active carrier and the Null carrier as shown in FIG. 29, and is appropriately changed according to the range of the subcarrier in which the Active carrier and the Null carrier are arranged. Value.
- a COM is a reference position for the arrangement correlation calculation, and Y COMB (0 + A), Y COMB (1 + A), Y COMB (2 + A),..., Y COMB (852 + A) are P1 broadband fc error detection and correction unit 155.
- This is a set of output signals of the complex multiplier 171 that obtains the maximum value of the power of the arrangement correlation when it is assumed that there is no wideband carrier frequency error amount in the input signal.
- the power calculation unit 173 calculates the power of the arrangement correlation from the arrangement correlation value sequentially input from the arrangement correlation calculation unit 172, and outputs the calculated arrangement correlation power value to the maximum value detection unit 174.
- Maximum value detection section 174 detects the maximum power value from the power values of the arrangement correlation sequentially input from power calculation section 173, and sets the shift amount for obtaining the maximum power value in units of subcarrier intervals of P1 symbols.
- the frequency error amount (broadband carrier frequency error amount) is output to the correction unit 180 and the fc correction unit 102 of FIG.
- correction section 180 Based on the wideband carrier frequency error amount input from maximum value detection section 174, correction section 180 uses the wideband carrier of the output signal of P1 orthogonal transform section 153U (the complex baseband signal in the frequency domain of the effective symbol section of P1 symbols). Perform frequency offset correction. Then, the correction unit 180 uses the active carrier arrangement sequence input from the CDS table generation unit 154 to extract only the active carrier from the complex baseband signal in the frequency domain in which the shift of the wideband carrier frequency is corrected. The extracted active carrier is output to the P1 decoding unit 156 in FIG. 4 (descramble unit 191 in FIG. 7 described later).
- FIG. 7 is a configuration diagram of the P1 decoding unit 156 of FIG.
- the P1 decoding unit 156 includes a descrambling unit 191, a differential demodulation unit 192, and a pattern matching unit 193. Note that the P1 decoding unit 156 performs decoding processing of the P1 symbol using only the S1 signal in the low frequency region of the P1 symbol.
- the descrambler 191 receives the signal sequence Act of the active carrier of the P1 symbol from the P1 broadband fc error detection correction unit 155 (correction unit 180 in FIG. 6) in FIG.
- the descrambling unit 191 performs the descrambling shown in (Expression 9) above on the signal sequence Act of the active carrier, and outputs the descrambled signal sequence DESCR to the differential demodulation unit 192.
- the signal Act i is descrambled as shown in (Equation 10) above, and the descrambled signal DESCR i is output to the differential demodulator 192.
- the processing of the differential demodulation unit 192 is expressed by the above (Equation 11), and the differential demodulation performed by the differential demodulation unit 192 is demodulation corresponding to DBPSK.
- the signal DEMOD i is output as “0”, but may be output as “1”.
- the pattern matching unit 193 converts the signals DEMOD 0 , DEMOD 1 ,..., DEMOD 319 differentially demodulated by the differential demodulation unit 192 into signal sequences as shown in the above (Equation 12) and (Equation 13). It is divided into DEMOD_CSS S1 (corresponding to S1 signal) and signal sequence DEMOD_CSS S2 (corresponding to S2 signal).
- the pattern matching unit 193 obtains a correlation CORR S1, k between each of the series CSS S1, k and the series DEMOD_CSS S1 in FIG. 31, as shown in the above (Expression 14), and as shown in the above (Expression 15). , The correlation CORR S2, k between each series CSS S2, k and the series DEMOD_CSS S2 in FIG.
- the pattern matching unit 193 outputs a 3-bit S1 signal corresponding to the sequence CSS S1, k having the maximum correlation value among the eight correlation values calculated using the above (Equation 14) (FIG. 31). Reference) is estimated as the transmitted S1 signal. Also, the pattern matching unit 193 generates a 4-bit S2 signal corresponding to the sequence CSS S2, k that takes the maximum correlation value among the 16 correlation values calculated using the above (Equation 15) (FIG. 31). Reference) is estimated as the transmitted S2 signal. The pattern matching unit 193 acquires P1 transmission information using the estimated S1 signal and S2 signal.
- the P1 decoding unit 156 uses only the S1 signal in the lower frequency domain among the S1 signal in the lower frequency domain and the S1 signal in the higher frequency domain in the P1 symbol decoding process.
- the present invention is not limited to this, and both may be used, or only the S1 signal in the high frequency region may be used. In the former case, since the S1 signal can be estimated using two S1 signals having different frequency bands, the estimation accuracy of the S1 signal can be improved.
- the differential demodulation unit 192 in the P1 decoding unit 156 performs the hard decision
- the present invention is not limited to this, and the hard decision may not be performed.
- DESCR 0 is output as DEMOD 0 to the pattern matching unit 193.
- the pattern matching 193 performs correlation calculation using the following (Equation 17) and the following (Equation 18) instead of the above (Equation 14) and the above (Equation 15).
- the P1 decoding unit 156 performs pattern matching after differential demodulation.
- the transmission system is subjected to error correction coding.
- error correction may be performed after differential demodulation, and decoding processing may be performed using the one with the lowest error.
- the signal in the previous guard interval section and the signal in the rear guard interval section of the P1 symbol are frequency-shifted so that the frequency for one subcarrier is higher than the signal in the effective symbol section of the P1 symbol. is there. That is, the frequency position of the signal in the front guard interval section and the signal in the rear interval section of the P1 symbol is higher by one subcarrier than the frequency position of the signal in the effective symbol section of the P1 symbol (FIG. 37). reference).
- the output of the P1 narrowband fc error detection correction unit 152 uses the effective symbol period of the main wave of the P1 symbol as the orthogonal transformation execution period.
- the subcarrier distribution in the frequency domain of a signal (output signal of the P1 orthogonal transform unit 153U) obtained as a result of orthogonal transform (for example, FFT) of the signal is as shown in FIG.
- orthogonal transform for example, FFT
- the delayed wave component for the null carrier between the two The subcarrier position where appears is different.
- the signal component of the Active carrier is strengthened and the signal component of the Null carrier is weakened.
- the wideband carrier frequency error amount can be accurately estimated to correct the shift of the wideband carrier frequency error, and the S1 signal and the S2 signal can be acquired correctly.
- the complex conjugate operation it is possible to remove the uncertainty of the polarity of the DBPSK-added signal added to the Active carrier without calculating the power of the subcarrier (Active carrier, Null carrier). And since it is not power calculation, it is possible to suppress noise components having various phase components when integrating each tap in arrangement correlation calculation, and it is possible to accurately estimate the broadband carrier frequency error amount even in a noise environment. It can be carried out.
- the OFDM receiving apparatus includes an P1 wideband fc error detection correction unit 200 that is different from the P1 wideband fc error detection correction unit 155 of the OFDM reception apparatus 1 described in the first embodiment. Different from 1. However, the P1 broadband fc error detection / correction unit 200 is different from the P1 broadband fc error detection / correction unit 155 of the first embodiment in the mechanism of detecting the broadband carrier frequency error amount.
- FIG. 11 is a configuration diagram of the P1 broadband fc error detection correction unit 200. 11 also illustrates a P1 orthogonal transform unit 153U, a P1 orthogonal transform unit 153G, and a CDS table generation unit 154 in order to clarify the input to each unit of the P1 wideband fc error detection correction unit 200.
- the P1 broadband fc error detection / correction unit 200 includes a detection unit 210 and a correction unit 180.
- the detection unit 210 detects a frequency error amount (broadband carrier frequency error amount) in the P1 symbol subcarrier interval unit in the P1 symbol, and includes a power calculation unit 211U, a power calculation unit 211G, and a multiplication unit 212. And an arrangement correlation calculation unit (addition processing unit) 213 and a maximum value detection unit 214.
- the power calculation unit 211U calculates the power of the output signal of the P1 orthogonal transform unit 153U (the complex baseband signal in the frequency domain of the effective symbol period of the P1 symbol) for each subcarrier, and outputs the calculated power value to the multiplication unit 212. To do.
- the power calculation unit 211G calculates the power of the output signal of the P1 orthogonal transform unit 153G (complex baseband signal in the frequency domain of the combined guard interval section of the P1 symbol) for each subcarrier, and outputs the calculated power value to the multiplication unit 212. Output.
- the multiplication unit 212 For each subcarrier, the multiplication unit 212 outputs the output signal
- 2 is multiplied, and the multiplication result Y COMB (n) is output to the arrangement correlation calculation unit 213.
- a prior signal of the signal and the rear guard interval of the guard interval section is that the signal of the effective symbol section and a frequency shifted by f SH (one obtained by frequency shifting as subcarriers frequency is increased). For this reason, the output signal of the power calculation unit 211G is shifted to the high frequency side by one subcarrier with respect to the output signal of the power calculation unit 211U. Considering this, the output signal
- the arrangement correlation calculation unit 213 receives the arrangement sequence of Active carriers from the CDS table generation unit 154 and the output signal Y COMB of the multiplication unit 212.
- Arrangement correlation operation section 213 performs addition processing for adding the values of output signals of multiplication section 212 in subcarriers whose active carrier arrangement sequence value is “1” in a plurality of consecutive subcarriers.
- the subcarriers are sequentially shifted in units of one subcarrier in the subcarrier direction within a predetermined range (the arrangement correlation calculation unit 213 performs arrangement correlation calculation between the output signal of the multiplication unit 212 and the arrangement sequence of the Active carriers.
- the arrangement correlation calculation unit 213 sequentially outputs the addition value (placement correlation value) obtained as a result of the addition process to the maximum value detection unit 214.
- the maximum value detection unit 214 detects the maximum arrangement correlation value from the arrangement correlation values sequentially input from the arrangement correlation calculation unit 213, and sets the shift amount for obtaining the maximum arrangement correlation value as a sub-value of the P1 symbol.
- a frequency error amount in a unit of carrier interval (broadband carrier frequency error amount) is output to the correction unit 180 and the fc correction unit 102 in FIG.
- the correction unit 180 uses the wideband carrier frequency error amount input from the maximum value detection unit 214 to correct the shift of the wideband carrier frequency of the output signal of the P1 orthogonal transform unit 153U, and then extracts the active carrier. .
- the present embodiment in a multipath interference environment, it is possible to accurately estimate the wideband carrier frequency error amount to correct the shift of the wideband carrier frequency error, and to correctly acquire the S1 signal and the S2 signal. it can.
- the OFDM receiver of this embodiment includes a P1 broadband fc error detection correction unit 250 that is different from the P1 broadband fc error detection correction units 155 and 200 of the OFDM receiver described in the first and second embodiments. , Different from those OFDM receivers. However, the P1 wideband fc error detection / correction unit 250 is different from the P1 wideband fc error detection / correction units 155, 200 of the first and second embodiments in the mechanism of detecting the wideband carrier frequency error amount.
- FIG. 12 is a configuration diagram of the P1 wideband fc error detection correction unit 250.
- FIG. 12 also illustrates a P1 orthogonal transform unit 153U, a P1 orthogonal transform unit 153G, and a CDS table generation unit 154 in order to clarify the input to each unit of the P1 wideband fc error detection correction unit 250.
- the P1 broadband fc error detection correction unit 250 includes a detection unit 270 and a correction unit 180.
- the detection unit 270 detects a frequency error amount (broadband carrier frequency error amount) in the P1 symbol subcarrier interval unit in the P1 symbol, and includes an amplitude calculation unit 271U, an amplitude calculation unit 271G, and a multiplication unit 272. And an arrangement correlation calculation unit (addition processing unit) 273 and a maximum value detection unit 274.
- the amplitude calculation unit 271U calculates the amplitude of the output signal of the P1 orthogonal transform unit 153U (complex baseband signal in the frequency domain of the effective symbol period of the P1 symbol) for each subcarrier, and outputs the calculated amplitude value to the multiplication unit 272. To do.
- the amplitude calculator 271G calculates the amplitude of the output signal of the P1 orthogonal transform unit 153G (complex baseband signal in the frequency domain of the combined guard interval section of the P1 symbol) for each subcarrier, and supplies the calculated amplitude value to the multiplier 272. Output.
- the multiplication unit 272 For each subcarrier, the multiplication unit 272 outputs the output signal
- a prior signal of the signal and the rear guard interval of the guard interval section is that the signal of the effective symbol section and a frequency shifted by f SH (one obtained by frequency shifting as subcarriers frequency is increased). For this reason, the output signal of the amplitude calculation unit 271G is shifted to the high frequency side by one subcarrier with respect to the output signal of the amplitude calculation unit 271U. Taking this into consideration, the output signal
- the arrangement correlation calculation unit 273 receives the arrangement sequence of Active carriers from the CDS table generation unit 154 and the output signal Y COMB of the multiplication unit 272. Arrangement correlation calculation section 273 performs addition processing for adding the values of the output signals of multiplication section 272 in subcarriers whose active carrier arrangement sequence value is “1” in a plurality of consecutive subcarriers. The subcarriers are sequentially shifted in units of one subcarrier in the subcarrier direction within a predetermined range (the arrangement correlation calculation unit 273 performs the arrangement correlation calculation between the output signal of the multiplication unit 272 and the arrangement sequence of the active carriers.
- the arrangement correlation calculation unit 273 sequentially outputs the addition value (placement correlation value) obtained as a result of the addition process to the maximum value detection unit 274.
- the maximum value detection unit 274 detects the maximum arrangement correlation value from the arrangement correlation values sequentially input from the arrangement correlation calculation unit 273, and sets the shift amount for obtaining the maximum arrangement correlation value as a sub-value of the P1 symbol.
- a frequency error amount in a unit of carrier interval (broadband carrier frequency error amount) is output to the correction unit 180 and the fc correction unit 102 in FIG.
- the correction unit 180 uses the wideband carrier frequency error amount input from the maximum value detection unit 274 to correct the shift of the wideband carrier frequency of the output signal of the P1 orthogonal transform unit 153U, and then extracts the active carrier. .
- the present embodiment in a multipath interference environment, it is possible to accurately estimate the wideband carrier frequency error amount to correct the shift of the wideband carrier frequency error, and to correctly acquire the S1 signal and the S2 signal. it can.
- the OFDM receiver of this embodiment includes a P1 wideband fc error detection correction unit 300 that is different from the P1 wideband fc error detection correction unit 155 of the OFDM receiver described in the first to third embodiments. Different from those OFDM receivers. However, the P1 wideband fc error detection and correction unit 300 differs from the P1 wideband fc error detection and correction unit 155 and the like in the mechanism of detecting the wideband carrier frequency error amount.
- FIG. 13 is a configuration diagram of the P1 wideband fc error detection correction unit 300.
- FIG. 13 also illustrates a P1 orthogonal transform unit 153U, a P1 orthogonal transform unit 153G, and a CDS table generation unit 154 in order to clarify the input to each unit of the P1 wideband fc error detection and correction unit 300.
- the P1 broadband fc error detection / correction unit 300 includes a detection unit 310 and a correction unit 180.
- the detection unit 310 detects a frequency error amount (wideband carrier frequency error amount) in the P1 symbol subcarrier interval unit in the P1 symbol, and includes a complex multiplication unit 171 and an arrangement correlation calculation unit (addition processing unit). 172, a power calculation unit 173, a power calculation unit 211U, an arrangement correlation calculation unit (addition processing unit) 311U, a power calculation unit 211G, an arrangement correlation calculation unit (addition processing unit) 311G, and a selection determination unit 312 Is provided.
- a frequency error amount wideband carrier frequency error amount
- the complex multiplication unit 171, the arrangement correlation calculation unit 172, and the power calculation unit 173 perform the above-described processing, and the output signal (the power value of the arrangement correlation) of the power calculation unit 173 is the selection determination unit 312 (the maximum value in FIG. 14 described later). Detection unit 331 and reliability detection unit 332).
- the power calculation unit 211U performs the above-described processing, and the output signal of the power calculation unit 211U is supplied to the arrangement correlation calculation unit 311U.
- the arrangement correlation calculation unit 311U receives the arrangement sequence of Active carriers from the CDS table generation unit 154 and the output signal
- the subcarriers are sequentially shifted in units of one subcarrier in the subcarrier direction within a predetermined range (the arrangement correlation calculation unit 311U calculates the arrangement correlation between the output signal of the power calculation unit 211U and the arrangement sequence of the active carriers) Is performed while sequentially shifting the output signal of the power calculation unit 211U used for the arrangement correlation calculation in units of one subcarrier in the subcarrier direction within a predetermined range).
- the arrangement correlation calculation unit 311U outputs the addition value (placement correlation value) obtained as a result of the addition process to the selection determination unit 312 (maximum value detection unit 331U and reliability detection unit 332U in FIG. 14 described later).
- the power calculation unit 211G performs the above-described processing, and the output signal of the power calculation unit 211G is supplied to the arrangement correlation calculation unit 311G.
- the arrangement correlation calculation unit 311G receives the arrangement sequence of Active carriers from the CDS table generation unit 154 and the output signal
- Arrangement correlation calculation section 311G performs an addition process for adding the values of the output signals of power calculation section 211G in subcarriers whose active carrier arrangement sequence value is “1” in a plurality of consecutive subcarriers.
- the subcarriers are sequentially shifted in units of one subcarrier in the subcarrier direction within a predetermined range (the arrangement correlation calculation unit 311G calculates the arrangement correlation between the output signal of the power calculation unit 211G and the arrangement sequence of the active carriers) Is performed while sequentially shifting the output signal of the power calculating unit 211G used for the arrangement correlation calculation in units of one subcarrier in the subcarrier direction within a predetermined range).
- the placement correlation calculation unit 311G outputs the addition value (placement correlation value) obtained as a result of the addition process to the selection determination unit 312 (maximum value detection unit 331G and reliability detection unit 332G in FIG. 14 described later).
- the selection determination unit 312 uses the output signal of the power calculation unit 173, the output signal of the arrangement correlation calculation unit 311U, and the output signal of the arrangement correlation calculation unit 311G to A frequency error amount (wideband carrier frequency error amount) in units of subcarrier intervals is detected, and the detected wideband carrier frequency error amount is output to the fc correction unit 102 and the correction unit 180 in FIG.
- the correction unit 180 uses the broadband carrier frequency error amount input from the selection determination unit 312 to correct the shift of the broadband carrier frequency of the output signal of the P1 orthogonal transform unit 153U, and then extracts the active carrier.
- FIG. 14 is a configuration diagram of the selection determination unit 312 of FIG. FIG. 14 also illustrates a power calculation unit 173, an arrangement correlation calculation unit 311U, and an arrangement correlation calculation unit 311G in order to clarify the input to each unit of the selection determination unit 312.
- the selection determination unit 312 includes a maximum value detection unit 331, a reliability detection unit 332, a maximum value detection unit 331U, a reliability detection unit 332U, a maximum value detection unit 331G, a reliability detection unit 332G, and a determination unit. 333 and a selection unit 334.
- the maximum value detection unit 331 detects the maximum power value from the power values of the arrangement correlation sequentially input from the power calculation unit 173, and determines the shift amount for obtaining the maximum power value in units of subcarrier intervals of the P1 symbol. This is output to the selection unit 334 as a frequency error amount candidate (a first candidate for a broadband carrier frequency error amount).
- the reliability detection unit 332 detects the maximum power value and the second largest power value from the power values of the arrangement correlation sequentially input from the power calculation unit 173, and sets the maximum power value to the second largest power value. And the division value (maximum power value ⁇ second largest power value) is output to the determination unit 333 as the reliability of the first candidate of the broadband carrier frequency error amount.
- Maximum value detecting section 331U detects the maximum arrangement correlation value from the arrangement correlation values sequentially input from arrangement correlation calculating section 311U, and determines the shift amount for obtaining the maximum arrangement correlation value as the subcarrier interval of P1 symbol. This is output to the selection unit 334 as a unit frequency error amount candidate (second candidate for a wideband carrier frequency error amount).
- the reliability detection unit 332U detects the maximum arrangement correlation value and the second largest arrangement correlation value from the arrangement correlation values sequentially input from the arrangement correlation calculation unit 311U, and sets the maximum arrangement correlation value to the second value. And the division value (maximum arrangement correlation value ⁇ second largest arrangement correlation value) is output to the determination unit 333 as the reliability of the second candidate for the wideband carrier frequency error amount.
- the maximum value detection unit 331G detects the maximum arrangement correlation value from the arrangement correlation values sequentially input from the arrangement correlation calculation unit 311G, and sets a shift amount one larger than the shift amount for obtaining the maximum arrangement correlation value to P1. This is output to the selection unit 334 as a frequency error amount candidate (third candidate for a wideband carrier frequency error amount) in symbol subcarrier interval units.
- the shift amount that is one larger than the shift amount for obtaining the maximum arrangement correlation value is set as the third candidate of the wideband carrier frequency error amount because the correction unit 180 performs correction of the shift of the wideband carrier frequency error.
- This is a signal related to the effective symbol period, and the signal in the guard interval period is shifted to a higher frequency by one subcarrier than the signal in the effective symbol period.
- the maximum value detection unit 331G may output the shift amount for obtaining the maximum arrangement correlation value to the selection unit 334 as the third candidate of the wideband carrier frequency error amount.
- the reliability detection unit 332G detects the maximum arrangement correlation value and the second largest arrangement correlation value from the arrangement correlation values sequentially input from the arrangement correlation calculation unit 311G, and sets the maximum arrangement correlation value to the second value. And the division value (the maximum arrangement correlation value / the second largest arrangement correlation value) is output to the determination unit 333 as the reliability of the third candidate for the wideband carrier frequency error amount.
- the determination unit 333 includes the reliability of the first candidate, the reliability of the second candidate, and the third reliability of the wideband carrier frequency error amount input from each of the reliability detection unit 332, the reliability detection unit 332U, and the reliability detection unit 332G.
- the reliability of the candidates is compared, and the candidate of the wideband carrier frequency error amount having the highest reliability (the highest reliability value) is selected from the first candidate, the second candidate, and the third candidate of the wideband carrier frequency error amount. To detect. Then, the determination unit 333 notifies the selection unit 334 of the broadband carrier frequency error amount candidate with the highest reliability.
- the arrangement correlation calculation an addition value of all the active carriers is obtained at the correct subcarrier position, and an addition value of a part of the active carrier and a part of the null carrier is obtained at the incorrect subcarrier position. For this reason, the power value of the arrangement correlation or the value of the arrangement correlation at the correct subcarrier position is maximized and becomes larger than the power value of the second largest arrangement correlation or the value of the arrangement correlation. It should be noted that half of the total number of active carriers is included at the position including the most active carriers at the wrong subcarrier position. For this reason, in a highly reliable signal, the maximum value is much larger than the second largest value, and as a result, the division value (reliability) obtained by dividing the maximum value by the second largest value is considerably larger than 1.
- the maximum value of the power of arrangement correlation or the maximum value of arrangement correlation is reduced, and the signal component of the Null carrier is increased.
- the power value of the second largest arrangement correlation or the value of the arrangement correlation becomes larger, the difference between the maximum value and the second largest value becomes smaller, or the maximum value is taken with an incorrect shift amount.
- the division value (reliability) obtained by dividing the maximum value by the second largest value is close to 1. Based on this, the reliability of detection of the broadband carrier frequency error amount is estimated based on the size of the division value.
- the selection unit 334 receives the first candidate, the second candidate, and the first candidate of the broadband carrier frequency error amount input from each of the maximum value detection unit 331, the maximum value detection unit 331U, and the maximum value detection unit 331G. 3 is selected as a broadband carrier frequency error amount candidate having the highest reliability from among the three candidates, and the selected broadband carrier frequency error amount candidate is used for correction. It outputs to the correction
- the complex multiplier 171, the arrangement correlation calculator 172, the power calculator 173, the maximum value detector 331, and the reliability detector 332 receive both the output signal from the orthogonal transform unit 153 ⁇ / b> U and the output signal from the orthogonal transform unit 153 ⁇ / b> G.
- This block is used to detect a first candidate for a wideband carrier frequency error amount and to execute a first detection process for detecting the reliability of the first candidate.
- the power calculation unit 211U, the arrangement correlation calculation unit 311U, the maximum value detection unit 331U, and the reliability detection unit 332U are the output signals of the orthogonal transformation unit 153U among the output signals of the orthogonal transformation unit 153U and the orthogonal transformation unit 153G.
- This is a block for executing a second detection process for detecting the second candidate of the wideband carrier frequency error amount using only the second candidate and detecting the reliability of the second candidate.
- the power calculation unit 211G, the arrangement correlation calculation unit 311G, the maximum value detection unit 331G, and the reliability detection unit 332G are the output signals of the orthogonal transformation unit 153G among the output signals of the orthogonal transformation unit 153U and the output signals of the orthogonal transformation unit 153G.
- (1) detection of a first candidate for a wideband carrier frequency error amount using both a signal in an effective symbol period and a signal in a combined guard interval period, and (2) only a signal in an effective symbol period is used.
- the detection of the second candidate of the wideband carrier frequency error amount performed, and (3) the detection of the third candidate of the wideband carrier frequency error amount using only the signal in the combined guard interval period, and using these three detection results is used.
- the broadband carrier frequency error amount is detected.
- the OFDM receiving apparatus includes a P1 wideband fc error detection correction unit 350 that is different from the P1 wideband fc error detection correction unit 155 of the OFDM receiving apparatus described in the first to fourth embodiments. Different from those OFDM receivers. However, the P1 broadband fc error detection / correction unit 350 differs from the P1 broadband fc error detection / correction unit 155 and the like in the mechanism of detecting the broadband carrier frequency error amount.
- FIG. 15 is a configuration diagram of the P1 broadband fc error detection correction unit 350. 15 also illustrates a P1 orthogonal transform unit 153U, a P1 orthogonal transform unit 153G, and a CDS table generation unit 154 in order to clarify the input to each unit of the P1 wideband fc error detection correction unit 350.
- the P1 broadband fc error detection correction unit 350 includes a detection unit 370 and a correction unit 180.
- the detection unit 370 detects a frequency error amount (broadband carrier frequency error amount) in the P1 symbol subcarrier interval unit in the P1 symbol, and includes a power calculation unit 211U, a power calculation unit 211G, and a multiplication unit 212.
- the power calculation unit 211U, the power calculation unit 211G, and the placement correlation calculation unit 213 perform the above-described processing, and the output signal (placement correlation value) of the placement correlation calculation unit 213 is a selection determination unit 371 (the maximum value in FIG. 16 described later). Detection unit 391 and reliability detection unit 392).
- the power calculation unit 211U and the placement correlation calculation unit 311U perform the above-described processing, and the output signal (placement correlation value) of the placement correlation calculation unit 311U is selected and determined by a selection determination unit 371 (a maximum value detection unit 331U and a reliability detection unit 331U in FIG. 16 described later). Degree detector 332U).
- the power calculation unit 211G and the arrangement correlation calculation unit 311G perform the above-described processing, and the output signal (the arrangement correlation value) of the arrangement correlation calculation unit 311G is selected and determined by a selection determination unit 371 (a maximum value detection unit 331G and a reliability detection unit 331G in FIG. 16 described later). Degree detector 332G).
- the selection determination unit 371 uses the output signal of the arrangement correlation calculation unit 213, the output signal of the arrangement correlation calculation unit 311U, and the output signal of the arrangement correlation calculation unit 311G to generate a P1 symbol. 3 is detected, and the detected wideband carrier frequency error amount is output to the fc correction unit 102 and the correction unit 180 of FIG.
- the correction unit 180 extracts the active carrier after correcting the wideband carrier frequency shift of the output signal of the P1 orthogonal transform unit 153U using the wideband carrier frequency error amount input from the selection determining unit 371.
- FIG. 16 is a block diagram of the selection determining unit 371 in FIG. Note that FIG. 16 also illustrates an arrangement correlation calculation unit 213, an arrangement correlation calculation unit 311U, and an arrangement correlation calculation unit 311G in order to clarify the input to each unit of the selection determination unit 371.
- the selection determination unit 371 includes a maximum value detection unit 391, a reliability detection unit 392, a maximum value detection unit 331U, a reliability detection unit 332U, a maximum value detection unit 331G, a reliability detection unit 332G, and a determination unit. 393 and a selection unit 394.
- Maximum value detecting section 391 detects the maximum arrangement correlation value from the arrangement correlation values sequentially input from arrangement correlation calculating section 213, and determines the shift amount for obtaining the maximum arrangement correlation value as the subcarrier interval of P1 symbol. This is output to the selection unit 394 as a unit frequency error amount candidate (a first candidate for a broadband carrier frequency error amount).
- the reliability detection unit 392 detects the maximum arrangement correlation value and the second largest arrangement correlation value from the arrangement correlation values sequentially input from the arrangement correlation calculation unit 213, and sets the maximum arrangement correlation value to the second value. And the division value (maximum arrangement correlation value ⁇ second largest arrangement correlation value) is output to the determination unit 393 as the reliability of the first candidate of the wideband carrier frequency error amount.
- the maximum value detection unit 331U and the reliability detection unit 332U perform the above-described processing, respectively, detect the second candidate of the broadband carrier frequency error amount and the reliability thereof, and detect the second candidate of the detected broadband carrier frequency error amount and the second candidate thereof.
- the reliability is output to the selection unit 394 and the determination unit 393.
- the maximum value detection unit 331G and the reliability detection unit 332G perform the above-described processing, respectively, detect the third candidate of the wideband carrier frequency error amount and the reliability thereof, and detect the third candidate of the detected wideband carrier frequency error amount and The reliability is output to the selection unit 394 and the determination unit 393.
- the determination unit 393 includes the reliability of the first candidate, the reliability of the second candidate, and the third reliability of the broadband carrier frequency error amount input from each of the reliability detection unit 392, the reliability detection unit 332U, and the reliability detection unit 332G.
- the reliability of the candidates is compared, and the candidate of the wideband carrier frequency error amount having the highest reliability (the highest reliability value) is selected from the first candidate, the second candidate, and the third candidate of the wideband carrier frequency error amount. To detect. Then, the determination unit 393 notifies the selection unit 394 of the candidate for the broadband carrier frequency error amount with the highest reliability.
- the selection unit 394 receives the first candidate, the second candidate, and the first candidate of the wideband carrier frequency error amount input from each of the maximum value detection unit 391, the maximum value detection unit 331U, and the maximum value detection unit 331G. 3 is selected as a broadband carrier frequency error amount candidate having the highest reliability from among the three candidates, and the selected broadband carrier frequency error amount candidate is used for correction. It outputs to the correction
- the power calculation unit 211U, the power calculation unit 211G, the multiplication unit 212, the arrangement correlation calculation unit 213, the maximum value detection unit 391, and the reliability detection unit 392 are the output signal of the orthogonal transform unit 153U and the output signal of the orthogonal transform unit 153G. And a first detection process for detecting the first candidate of the wideband carrier frequency error amount and detecting the reliability of the first candidate.
- the power calculation unit 211U, the arrangement correlation calculation unit 311U, the maximum value detection unit 331U, and the reliability detection unit 332U are the output signals of the orthogonal transformation unit 153U among the output signals of the orthogonal transformation unit 153U and the orthogonal transformation unit 153G.
- This is a block for executing a second detection process for detecting the second candidate of the wideband carrier frequency error amount using only the second candidate and detecting the reliability of the second candidate.
- the power calculation unit 211G, the arrangement correlation calculation unit 311G, the maximum value detection unit 331G, and the reliability detection unit 332G are the output signals of the orthogonal transformation unit 153G among the output signals of the orthogonal transformation unit 153U and the output signals of the orthogonal transformation unit 153G.
- wideband carrier frequency error not only in a multipath interference environment or a noise environment, but also in an environment where impulse noise locally exists in the previous guard interval period, the subsequent guard interval period, and the effective symbol period.
- the quantity can be estimated accurately.
- a square calculation unit that performs a square calculation of the output signal of the power calculation unit 211U and outputs the result of the square calculation to the arrangement correlation calculation unit 311U is added, and a square calculation of the output signal of the power calculation unit 211G And a square calculation unit that outputs the result of the square calculation to the arrangement correlation calculation unit 311G may be added.
- the OFDM receiving apparatus includes a P1 wideband fc error detection correction unit 400 that is different from the P1 wideband fc error detection correction unit 155 of the OFDM reception apparatus described in the first to fifth embodiments. Different from those OFDM receivers. However, the P1 broadband fc error detection and correction unit 400 differs from the P1 broadband fc error detection and correction unit 155 and the like in the mechanism of detecting the broadband carrier frequency error amount.
- FIG. 17 is a configuration diagram of the P1 broadband fc error detection correction unit 400. Note that FIG. 17 also illustrates a P1 orthogonal transform unit 153U, a P1 orthogonal transform unit 153G, and a CDS table generation unit 154 in order to clarify the input to each unit of the P1 wideband fc error detection correction unit 400.
- the P1 broadband fc error detection correction unit 400 includes a detection unit 410 and a correction unit 180.
- the detection unit 410 detects a frequency error amount (wideband carrier frequency error amount) in the P1 symbol subcarrier interval unit in the P1 symbol, and includes an amplitude calculation unit 271U, an amplitude calculation unit 271G, and a multiplication unit 272.
- a selection determination unit 413 is a selection determination unit 413.
- the amplitude calculation unit 271U, the amplitude calculation unit 271G, the multiplication unit 272, and the arrangement correlation calculation unit 273 perform the above-described processing, and the output signal (the value of the arrangement correlation) of the arrangement correlation calculation unit 273 is a selection determination unit 413 (a figure to be described later). 18 maximum value detectors 431 and reliability detectors 432).
- the amplitude calculation unit 271U performs the above-described processing, and the output signal of the amplitude calculation unit 271U is supplied to the arrangement correlation calculation unit 411U.
- the arrangement correlation calculation unit 411U receives an arrangement sequence of Active carriers from the CDS table generation unit 154 and an output signal
- the subcarriers are sequentially shifted in units of one subcarrier in the subcarrier direction within a predetermined range (the arrangement correlation calculation unit 411U calculates the arrangement correlation between the output signal of the amplitude calculation unit 271U and the arrangement sequence of the active carriers) Is performed while sequentially shifting the output signal of the amplitude calculation unit 271U used for the arrangement correlation calculation in units of one subcarrier in the subcarrier direction within a predetermined range).
- the arrangement correlation calculation unit 411U outputs the addition value (placement correlation value) obtained as a result of the addition process to the power calculation unit 412U.
- the power calculation unit 412U calculates the power of the arrangement correlation from the arrangement correlation values sequentially input from the arrangement correlation calculation unit 411U, and selects the calculated arrangement correlation power value by the selection determination unit 413 (maximum value detection in FIG. 18 described later).
- Unit 431U and reliability detection unit 432U are the power calculation unit 412U.
- the amplitude calculation unit 271G performs the above-described processing, and the output signal of the amplitude calculation unit 271G is supplied to the arrangement correlation calculation unit 411U.
- the arrangement correlation calculation unit 411U receives the arrangement sequence of Active carriers from the CDS table generation unit 154 and the output signal
- Arrangement correlation calculation section 411G performs an addition process of adding the value of the output signal of amplitude calculation section 271G in the subcarrier whose active carrier arrangement sequence value is “1” in a plurality of consecutive subcarriers.
- the subcarriers are sequentially shifted in units of one subcarrier in the subcarrier direction within a predetermined range (the arrangement correlation calculation unit 411G calculates the arrangement correlation between the output signal of the amplitude calculation unit 271G and the arrangement sequence of the Active carriers) Is performed while sequentially shifting the output signal of the amplitude calculation unit 271G used for the arrangement correlation calculation in units of one subcarrier in the subcarrier direction within a predetermined range).
- the arrangement correlation calculation unit 411G outputs the addition value (position correlation value) obtained as a result of the addition process to the power calculation unit 412G.
- the power calculation unit 412G calculates the power of the arrangement correlation from the arrangement correlation values sequentially input from the arrangement correlation calculation unit 411G, and selects the calculated arrangement correlation power value as a selection determination unit 413 (maximum value detection in FIG. 18 described later).
- Unit 431G and reliability detection unit 432G are examples of the power calculation unit 412G.
- the selection determination unit 413 uses the output signal of the arrangement correlation calculation unit 273, the output signal of the power calculation unit 412U, and the output signal of the power calculation unit 412G to sub-subscribe the P1 symbol.
- a frequency error amount (wideband carrier frequency error amount) in units of carrier intervals is detected, and the detected wideband carrier frequency error amount is output to the fc correction unit 102 and the correction unit 180 in FIG.
- the correction unit 180 uses the broadband carrier frequency error amount input from the selection determination unit 413 to correct the shift of the broadband carrier frequency of the output signal of the P1 orthogonal transform unit 153U, and then extracts the Active carrier.
- FIG. 18 is a configuration diagram of the selection determining unit 413 in FIG. FIG. 18 also shows an arrangement correlation calculation unit 273, a power calculation unit 412U, and a power calculation unit 412G in order to clarify the input to each unit of the selection determination unit 413.
- the selection determination unit 413 includes a maximum value detection unit 431, a reliability detection unit 432, a maximum value detection unit 431U, a reliability detection unit 432U, a maximum value detection unit 431G, a reliability detection unit 432G, and a determination unit. 433 and a selection unit 434.
- the maximum value detection unit 431 detects the maximum arrangement correlation value from the arrangement correlation values sequentially input from the arrangement correlation calculation unit 273, and sets the shift amount for obtaining the maximum arrangement correlation value as a sub-value of the P1 symbol.
- the result is output to the selection unit 434 as a frequency error amount candidate (first candidate for a wideband carrier frequency error amount) in carrier interval units.
- the reliability detection unit 432 detects the maximum arrangement correlation value and the second largest arrangement correlation value from the arrangement correlation values sequentially input from the arrangement correlation calculation unit 273, and determines the maximum arrangement correlation value. Divide by the second largest arrangement correlation value, and output the division value (maximum arrangement correlation value ⁇ second largest arrangement correlation value) to determination section 433 as the reliability of the first candidate of the wideband carrier frequency error amount To do.
- Maximum value detection section 431U detects the maximum arrangement correlation power value from the arrangement correlation power values sequentially input from power calculation section 412U, and sets the shift amount for obtaining the maximum arrangement correlation power value as a sub-value of P1 symbol. This is output to the selection unit 434 as a frequency error amount candidate (second candidate for a wideband carrier frequency error amount) in units of carrier intervals.
- the reliability detection unit 432U detects the maximum arrangement correlation power value and the second largest arrangement correlation power value from the arrangement correlation power values sequentially input from the power calculation unit 412U, and the maximum arrangement correlation power value. Is divided by the power value of the second largest arrangement correlation, and the division value (the power value of the largest arrangement correlation ⁇ the power value of the second largest arrangement correlation) is determined as the reliability of the second candidate for the wideband carrier frequency error amount. Output to the unit 433.
- the maximum value detection unit 431G detects the maximum arrangement correlation power value from the arrangement correlation power value sequentially input from the power calculation unit 412G, and shifts by one larger than the shift amount for obtaining the maximum arrangement correlation power value. Is output to the selection unit 434 as a frequency error amount candidate (third candidate of wideband carrier frequency error amount) in P1 symbol subcarrier interval units. Here, the shift amount one larger than the shift amount for obtaining the maximum arrangement correlation power value is set as the third candidate for the wideband carrier frequency error amount.
- the correction unit 180 performs correction of the shift of the wideband carrier frequency error. Is a signal related to the effective symbol period, and the signal in the guard interval period is shifted to a higher frequency by one subcarrier than the signal in the effective symbol period.
- the maximum value detection unit 431G may output the shift amount for obtaining the maximum arrangement correlation power value to the selection unit 434 as the third candidate of the wideband carrier frequency error amount.
- the reliability detection unit 432G detects the maximum arrangement correlation power value and the second largest arrangement correlation power value from the arrangement correlation power values sequentially input from the power calculation unit 412G, and the maximum arrangement correlation power value. Is divided by the power value of the second largest arrangement correlation, and the division value (the power value of the largest arrangement correlation ⁇ the power value of the second largest arrangement correlation) is determined as the reliability of the third candidate for the wideband carrier frequency error amount. Output to the unit 433.
- the determination unit 433 includes the reliability of the first candidate, the reliability of the second candidate, and the third reliability of the broadband carrier frequency error amount input from each of the reliability detection unit 432, the reliability detection unit 432U, and the reliability detection unit 432G.
- the reliability of the candidates is compared, and the candidate of the wideband carrier frequency error amount having the highest reliability (the highest reliability value) is selected from the first candidate, the second candidate, and the third candidate of the wideband carrier frequency error amount. To detect. Then, the determination unit 433 notifies the selection unit 434 of the broadband carrier frequency error amount candidate with the highest reliability.
- the selection unit 434 receives the first candidate, the second candidate, and the first candidate of the wideband carrier frequency error amount input from each of the maximum value detection unit 431, the maximum value detection unit 431U, and the maximum value detection unit 431G according to the notification of the determination unit 433. 3 is selected as a broadband carrier frequency error amount candidate having the highest reliability from among the three candidates, and the selected broadband carrier frequency error amount candidate is used for correction. It outputs to the correction
- the amplitude calculation unit 271U, the amplitude calculation unit 271G, the multiplication unit 272, the arrangement correlation calculation unit 273, the maximum value detection unit 431, and the reliability detection unit 432 are the output signal of the orthogonal transformation unit 153U and the output signal of the orthogonal transformation unit 153G.
- a first detection process for detecting the first candidate of the wideband carrier frequency error amount and detecting the reliability of the first candidate is the output signal of the orthogonal transformation unit 153U and the output signal of the orthogonal transformation unit 153G.
- the amplitude calculation unit 271U, the arrangement correlation calculation unit 411U, the power calculation unit 412U, the maximum value detection unit 431U, and the reliability detection unit 432U are orthogonally transformed among the output signal of the orthogonal transformation unit 153U and the output signal of the orthogonal transformation unit 153G.
- the amplitude calculation unit 271G, the arrangement correlation calculation unit 411G, the power calculation unit 412G, the maximum value detection unit 431G, and the reliability detection unit 432G are orthogonally transformed among the output signal of the orthogonal transformation unit 153U and the output signal of the orthogonal transformation unit 153G. It is a block for executing a third detection process for detecting a third candidate for the broadband carrier frequency error amount using only the output signal of the unit 153G and detecting the reliability of the third candidate.
- wideband carrier frequency error not only in a multipath interference environment or a noise environment, but also in an environment where impulse noise locally exists in the previous guard interval period, the subsequent guard interval period, and the effective symbol period.
- the reception performance can be improved by reducing erroneous estimation of the amount.
- the OFDM receiver of this embodiment includes a P1 wideband fc error detection correction unit 450 that is different from the P1 wideband fc error detection correction unit 155 of the OFDM receiver described in the first to sixth embodiments. Different from those OFDM receivers. However, the P1 broadband fc error detection and correction unit 450 is different from the P1 broadband fc error detection and correction unit 155 and the like in the mechanism of detecting the broadband carrier frequency error amount.
- FIG. 19 is a configuration diagram of the P1 broadband fc error detection correction unit 450.
- FIG. 19 also shows a P1 orthogonal transform unit 153U, a P1 orthogonal transform unit 153G, and a CDS table generation unit 154 in order to clarify the input to each unit of the P1 wideband fc error detection correction unit 450.
- the P1 broadband fc error detection / correction unit 450 includes a detection unit 470 and a correction unit 180.
- the detection unit 470 detects a frequency error amount (wideband carrier frequency error amount) in the P1 symbol subcarrier interval unit in the P1 symbol, and includes an amplitude calculation unit 271U, an amplitude calculation unit 271G, and a multiplication unit 272.
- the amplitude calculation unit 271U, the amplitude calculation unit 271G, the multiplication unit 272, and the arrangement correlation calculation unit 273 perform the above-described processing, and the output signal (the value of the arrangement correlation) of the arrangement correlation calculation unit 273 is a selection determination unit 471 (a diagram to be described later). 20 maximum value detectors 431 and reliability detectors 432).
- the power calculation unit 211U and the arrangement correlation calculation unit 311U perform the above-described processing, and the output signal (the arrangement correlation value) of the arrangement correlation calculation unit 311U is selected and selected by a selection determination unit 471 (a maximum value detection unit 331U and a reliability detection unit 331U in FIG. 20 described later). Degree detector 332U).
- the power calculation unit 211G and the placement correlation calculation unit 311G perform the above-described processing, and the output signal (placement correlation value) of the placement correlation calculation unit 311G is selected and selected by a selection determination unit 471 (maximum value detection unit 331G and reliability shown in FIG. 20 described later). Degree detector 332G).
- the selection determination unit 471 uses the output signal of the arrangement correlation calculation unit 273, the output signal of the arrangement correlation calculation unit 311U, and the output signal of the arrangement correlation calculation unit 311G to generate the P1 symbol. 3 is detected, and the detected wideband carrier frequency error amount is output to the fc correction unit 102 and the correction unit 180 of FIG.
- the correction unit 180 extracts the active carrier after correcting the wideband carrier frequency shift of the output signal of the P1 orthogonal transform unit 153U using the wideband carrier frequency error amount input from the selection determining unit 471.
- FIG. 20 is a configuration diagram of the selection determining unit 471 in FIG. Note that FIG. 20 also illustrates an arrangement correlation calculation unit 273, an arrangement correlation calculation unit 311U, and an arrangement correlation calculation unit 311G in order to clarify the input to each unit of the selection determination unit 471.
- the selection determination unit 471 includes a maximum value detection unit 431, a reliability detection unit 432, a maximum value detection unit 331U, a reliability detection unit 332U, a maximum value detection unit 331G, a reliability detection unit 332G, and a determination unit. 491 and a selection unit 492.
- the maximum value detection unit 431 and the reliability detection unit 432 perform the above-described processing, respectively, detect the first candidate of the wideband carrier frequency error amount and its reliability, and detect the first candidate of the detected wideband carrier frequency error amount and its The reliability is output to the selection unit 492 and the determination unit 491.
- the maximum value detection unit 331U and the reliability detection unit 332U perform the above-described processing, respectively, detect the second candidate of the broadband carrier frequency error amount and the reliability thereof, and detect the second candidate of the detected broadband carrier frequency error amount and the second candidate thereof.
- the reliability is output to the selection unit 492 and the determination unit 491.
- the maximum value detection unit 331G and the reliability detection unit 332G perform the above-described processing, respectively, detect the third candidate of the wideband carrier frequency error amount and the reliability thereof, and detect the third candidate of the detected wideband carrier frequency error amount and The reliability is output to the selection unit 492 and the determination unit 491.
- the determination unit 491 includes the reliability of the first candidate, the reliability of the second candidate, and the third reliability of the wideband carrier frequency error amount input from each of the reliability detection unit 432, the reliability detection unit 332U, and the reliability detection unit 332G.
- the reliability of the candidates is compared, and the candidate of the wideband carrier frequency error amount having the highest reliability (the highest reliability value) is selected from the first candidate, the second candidate, and the third candidate of the wideband carrier frequency error amount. To detect. Then, the determination unit 491 notifies the selection unit 492 of the broadband carrier frequency error amount candidate with the highest reliability.
- the selection unit 492 follows the notification of the determination unit 491, the first candidate, the second candidate, and the first candidate of the wideband carrier frequency error amount input from each of the maximum value detection unit 431, the maximum value detection unit 331U, and the maximum value detection unit 331G. 3 is selected as a broadband carrier frequency error amount candidate having the highest reliability from among the three candidates, and the selected broadband carrier frequency error amount candidate is used for correction. It outputs to the correction
- the amplitude calculation unit 271U, the amplitude calculation unit 271G, the multiplication unit 272, the arrangement correlation calculation unit 273, the maximum value detection unit 431, and the reliability detection unit 432 are the output signal of the orthogonal transformation unit 153U and the output signal of the orthogonal transformation unit 153G.
- a first detection process for detecting the first candidate of the wideband carrier frequency error amount and detecting the reliability of the first candidate is the output signal of the orthogonal transformation unit 153U and the output signal of the orthogonal transformation unit 153G.
- the power calculation unit 211U, the arrangement correlation calculation unit 311U, the maximum value detection unit 331U, and the reliability detection unit 332U are the output signals of the orthogonal transformation unit 153U among the output signals of the orthogonal transformation unit 153U and the orthogonal transformation unit 153G.
- This is a block for executing a second detection process for detecting the second candidate of the wideband carrier frequency error amount using only the second candidate and detecting the reliability of the second candidate.
- the power calculation unit 211G, the arrangement correlation calculation unit 311G, the maximum value detection unit 331G, and the reliability detection unit 332G are the output signals of the orthogonal transformation unit 153G among the output signals of the orthogonal transformation unit 153U and the output signals of the orthogonal transformation unit 153G.
- wideband carrier frequency error not only in a multipath interference environment or a noise environment, but also in an environment where impulse noise locally exists in the previous guard interval period, the subsequent guard interval period, and the effective symbol period.
- the quantity can be estimated accurately.
- the OFDM receiving apparatus includes a P1 wideband fc error detection correction unit 500 that is different from the P1 wideband fc error detection correction unit 155 of the OFDM reception apparatus described in the first to seventh embodiments. Different from those OFDM receivers. However, the P1 broadband fc error detection and correction unit 500 is different from the P1 broadband fc error detection and correction unit 155 and the like in the mechanism of detecting the broadband carrier frequency error amount.
- FIG. 21 is a configuration diagram of the P1 broadband fc error detection and correction unit 500.
- FIG. 21 also illustrates a P1 orthogonal transform unit 153U, a P1 orthogonal transform unit 153G, and a CDS table generation unit 154 in order to clarify the input to each unit of the P1 wideband fc error detection correction unit 500.
- the P1 broadband fc error detection / correction unit 500 includes a detection unit 510 and a correction unit 180.
- the detection unit 510 detects a frequency error amount (wideband carrier frequency error amount) of the P1 symbol in the P1 symbol subcarrier interval unit, and includes a complex multiplication unit 171 and an arrangement correlation calculation unit (addition processing unit). 172, an amplitude calculation unit 511, a power calculation unit 211U, an arrangement correlation calculation unit (addition processing unit) 311U, a power calculation unit 211G, an arrangement correlation calculation unit (addition processing unit) 311G, and a selection determination unit 512 Is provided.
- the complex multiplication unit 171 and the arrangement correlation calculation unit 172 perform the above-described processing, and the output signal (position correlation value) of the arrangement correlation calculation unit 172 is supplied to the amplitude calculation unit 511.
- the amplitude calculation unit 511 performs processing for calculating the amplitude of the arrangement correlation value sequentially input from the arrangement correlation calculation unit 172, and selects the calculated arrangement correlation amplitude value as a selection determination unit 512 (maximum value detection in FIG. 22 described later).
- the power calculation unit 211U and the arrangement correlation calculation unit 311U perform the above-described processing, and the output signal (the value of the arrangement correlation) of the arrangement correlation calculation unit 311U is a selection determination unit 512 (maximum value detection unit 331U and reliability shown in FIG. 22 described later). Degree detector 332U).
- the power calculation unit 211G and the placement correlation calculation unit 311G perform the above-described processing, and the output signal (placement correlation value) of the placement correlation calculation unit 311G is selected and selected by the selection determination unit 512 (maximum value detection unit 331G and reliability shown in FIG. 22 described later). Degree detector 332G).
- the selection determination unit 512 uses the output signal of the amplitude calculation unit 511, the output signal of the arrangement correlation calculation unit 311U, and the output signal of the arrangement correlation calculation unit 311G to A frequency error amount (wideband carrier frequency error amount) in units of subcarrier intervals is detected, and the detected wideband carrier frequency error amount is output to the fc correction unit 102 and the correction unit 180 in FIG.
- the correction unit 180 extracts the active carrier after correcting the wideband carrier frequency shift of the output signal of the P1 orthogonal transform unit 153U using the wideband carrier frequency error amount input from the selection determination unit 512.
- FIG. 22 is a configuration diagram of the selection determination unit 512 of FIG. Note that FIG. 22 also illustrates an amplitude calculation unit 511, an arrangement correlation calculation unit 311U, and an arrangement correlation calculation unit 311G in order to clarify the input to each unit of the selection determination unit 512.
- the selection determination unit 512 includes a maximum value detection unit 531, a reliability detection unit 532, a maximum value detection unit 331U, a reliability detection unit 332U, a maximum value detection unit 331G, a reliability detection unit 332G, and a determination unit. 533 and a selection unit 534.
- the maximum value detection unit 531 detects the maximum amplitude value from the amplitude values of the arrangement correlation sequentially input from the amplitude calculation unit 511, and determines the shift amount for obtaining the maximum amplitude value as a frequency error in subcarrier interval units of the P1 symbol. This is output to the selection unit 534 as a quantity candidate (a first candidate for the broadband carrier frequency error quantity).
- the reliability detection unit 532 detects the maximum amplitude value and the second largest amplitude value from the amplitude values of the arrangement correlation sequentially input from the amplitude calculation unit 511, and divides the maximum amplitude value by the second largest amplitude value. Then, the division value (maximum arrangement correlation amplitude value ⁇ second largest arrangement correlation amplitude value) is output to the determination unit 533 as the reliability of the first candidate of the wideband carrier frequency error amount.
- the maximum value detection unit 331U and the reliability detection unit 332U perform the above-described processing, respectively, detect the second candidate of the broadband carrier frequency error amount and the reliability thereof, and detect the second candidate of the detected broadband carrier frequency error amount and the second candidate thereof.
- the reliability is output to the selection unit 534 and the determination unit 533.
- the maximum value detection unit 331G and the reliability detection unit 332G perform the above-described processing, respectively, detect the third candidate of the wideband carrier frequency error amount and the reliability thereof, and detect the third candidate of the detected wideband carrier frequency error amount and The reliability is output to the selection unit 534 and the determination unit 533.
- the determination unit 533 includes the reliability of the first candidate, the reliability of the second candidate, and the third reliability of the broadband carrier frequency error amount input from each of the reliability detection unit 532, the reliability detection unit 332U, and the reliability detection unit 332G.
- the reliability of the candidates is compared, and the candidate of the wideband carrier frequency error amount having the highest reliability (the highest reliability value) is selected from the first candidate, the second candidate, and the third candidate of the wideband carrier frequency error amount. To detect. Then, the determination unit 533 notifies the selection unit 534 of the candidate for the broadband carrier frequency error amount with the highest reliability.
- the selection unit 534 receives the first candidate, the second candidate of the broadband carrier frequency error amount input from each of the maximum value detection unit 531, the maximum value detection unit 331U, and the maximum value detection unit 331G.
- the fc correction unit 102 in FIG. 3 selects a broadband carrier frequency error amount candidate having the highest reliability from among the third candidates, and uses the selected broadband carrier frequency error amount candidate for correction as a broadband carrier frequency error amount. And it outputs to the correction
- the complex multiplier 171, the arrangement correlation calculator 172, the amplitude calculator 511, the maximum value detector 531, and the reliability detector 532 receive both the output signal of the orthogonal transform unit 153 ⁇ / b> U and the output signal of the orthogonal transform unit 153 ⁇ / b> G.
- This block is used to detect a first candidate for a wideband carrier frequency error amount and to execute a first detection process for detecting the reliability of the first candidate.
- the power calculation unit 211U, the arrangement correlation calculation unit 311U, the maximum value detection unit 331U, and the reliability detection unit 332U are the output signals of the orthogonal transformation unit 153U among the output signals of the orthogonal transformation unit 153U and the orthogonal transformation unit 153G.
- This is a block for executing a second detection process for detecting the second candidate of the wideband carrier frequency error amount using only the second candidate and detecting the reliability of the second candidate.
- the power calculation unit 211G, the arrangement correlation calculation unit 311G, the maximum value detection unit 331G, and the reliability detection unit 332G are the output signals of the orthogonal transformation unit 153G among the output signals of the orthogonal transformation unit 153U and the output signals of the orthogonal transformation unit 153G.
- wideband carrier frequency error not only in a multipath interference environment or a noise environment, but also in an environment where impulse noise locally exists in the previous guard interval period, the subsequent guard interval period, and the effective symbol period.
- the quantity can be estimated accurately.
- the OFDM receiver of this embodiment includes a P1 wideband fc error detection correction unit 550 different from the P1 wideband fc error detection correction unit 155 of the OFDM receiver described in the first to eighth embodiments. Different from those OFDM receivers. However, the P1 wideband fc error detection / correction unit 550 is different from the P1 wideband fc error detection / correction unit 155 in the mechanism of detecting the wideband carrier frequency error amount.
- FIG. 23 is a block diagram of the P1 broadband fc error detection correction unit 550. 23 also illustrates a P1 orthogonal transform unit 153U, a P1 orthogonal transform unit 153G, and a CDS table generation unit 154 in order to clarify the input to each unit of the P1 wideband fc error detection correction unit 550.
- the P1 broadband fc error detection / correction unit 550 includes a detection unit 570 and a correction unit 180.
- the detection unit 570 detects a frequency error amount (wideband carrier frequency error amount) in the P1 symbol subcarrier interval unit in the P1 symbol, and includes a complex multiplication unit 171 and an arrangement correlation calculation unit (addition processing unit). 172, a power calculation unit 173, a power calculation unit 211U, an arrangement correlation calculation unit (addition processing unit) 311U, a square calculation unit 571U, a power calculation unit 211G, and an arrangement correlation calculation unit (addition processing unit) 311G. And a square calculation unit 571G and a selection determination unit 572.
- the complex multiplication unit 171, the arrangement correlation calculation unit 172, and the power calculation unit 173 perform the above-described processing, and the output signal (the power value of the arrangement correlation) of the power calculation unit 173 is the selection determination unit 572 (the maximum value in FIG. 24 described later). Detection unit 331 and reliability detection unit 332).
- the power calculation unit 211U and the arrangement correlation calculation unit 311U perform the above-described process, and the output signal (value of the arrangement correlation) of the arrangement correlation calculation unit 311U is supplied to the square calculation unit 571U.
- the square calculation unit 571U performs the square calculation of the arrangement correlation values sequentially input from the arrangement correlation calculation unit 311U, and selects the result of the square calculation as a selection determination unit 572 (maximum value detection unit 591U in FIG. 24 described later). And the reliability detection unit 592U).
- the power calculation unit 211G and the arrangement correlation calculation unit 311G perform the above-described processing, and the output signal (value of the arrangement correlation) of the arrangement correlation calculation unit 311G is supplied to the square calculation unit 571G.
- the square calculation unit 571G performs the square calculation of the arrangement correlation values sequentially input from the arrangement correlation calculation unit 311G, and selects the result of the square calculation as a selection determination unit 572 (maximum value detection unit 591G in FIG. 24 described later). And the reliability detection unit 592G).
- the selection determination unit 572 uses the output signal of the power calculation unit 173, the output signal of the square calculation unit 571U, and the output signal of the square calculation unit 571G to generate the P1 symbol.
- a frequency error amount (wideband carrier frequency error amount) in units of subcarrier intervals is detected, and the detected wideband carrier frequency error amount is output to the fc correction unit 102 and the correction unit 180 in FIG.
- the correction unit 180 corrects the wideband carrier frequency shift of the output signal of the P1 orthogonal transform unit 153U using the wideband carrier frequency error amount input from the selection determination unit 572, and then extracts the Active carrier.
- FIG. 24 is a configuration diagram of the selection determination unit 572 of FIG. 24 also shows a power calculation unit 173, a square calculation unit 571U, and a square calculation unit 571G in order to clarify the input to each unit of the selection determination unit 572.
- the selection determination unit 572 includes a maximum value detection unit 331, a reliability detection unit 332, a maximum value detection unit 591U, a reliability detection unit 592U, a maximum value detection unit 591G, a reliability detection unit 592G, and a determination unit. 593 and a selection unit 594.
- the maximum value detection unit 331 and the reliability detection unit 332 perform the above-described processes, respectively, detect the first candidate of the wideband carrier frequency error amount and the reliability thereof, and detect the first candidate of the detected wideband carrier frequency error amount and its The reliability is output to the selection unit 594 and the determination unit 593.
- the maximum value detection unit 591U detects the square value of the maximum arrangement correlation from the square value of the arrangement correlation sequentially input from the square calculation unit 571U, and calculates the shift amount for obtaining the square value of the maximum arrangement correlation.
- the result is output to selection section 594 as a frequency error amount candidate (second candidate for wideband carrier frequency error amount) in P1 symbol subcarrier interval units.
- the reliability detection unit 592U detects the square value of the maximum arrangement correlation and the square value of the second largest arrangement correlation from the square value of the arrangement correlation sequentially input from the square calculation unit 571U, and detects the maximum arrangement.
- the square value of the correlation is divided by the square value of the second largest arrangement correlation, and the divided value (the square value of the largest arrangement correlation / the square value of the second largest arrangement correlation) is calculated as the broadband carrier frequency error amount.
- the reliability of the second candidate is output to the determination unit 593.
- the maximum value detecting unit 591G detects the square value of the maximum arrangement correlation from the square value of the arrangement correlation sequentially input from the square calculation unit 571G, and from the shift amount to obtain the square value of the maximum arrangement correlation.
- the one larger shift amount is output to selection section 594 as a frequency error amount candidate (third candidate for wideband carrier frequency error amount) in the subcarrier interval unit of P1 symbol.
- the shift amount one larger than the shift amount for obtaining the maximum arrangement correlation power value is set as the third candidate for the wideband carrier frequency error amount.
- the correction unit 180 performs correction of the shift of the wideband carrier frequency error. Is a signal related to the effective symbol period, and the signal in the guard interval period is shifted to a higher frequency by one subcarrier than the signal in the effective symbol period.
- the maximum value detection unit 591G may output the shift amount for obtaining the maximum arrangement correlation power value to the selection unit 594 as the third candidate for the wideband carrier frequency error amount.
- the reliability detection unit 592G detects the square value of the maximum arrangement correlation and the square value of the second largest arrangement correlation from the square value of the arrangement correlation sequentially input from the square calculation unit 571G, and detects the maximum arrangement.
- the square value of the correlation is divided by the square value of the second largest arrangement correlation, and the divided value (the square value of the largest arrangement correlation / the square value of the second largest arrangement correlation) is calculated as the broadband carrier frequency error amount.
- the reliability of the third candidate is output to the determination unit 593.
- the determination unit 593 includes the reliability of the first candidate, the reliability of the second candidate, and the third reliability of the broadband carrier frequency error amount input from each of the reliability detection unit 332, the reliability detection unit 592U, and the reliability detection unit 592G.
- the reliability of the candidates is compared, and the candidate of the wideband carrier frequency error amount having the highest reliability (the highest reliability value) is selected from the first candidate, the second candidate, and the third candidate of the wideband carrier frequency error amount. To detect. Then, the determination unit 593 notifies the selection unit 594 of the candidate for the broadband carrier frequency error amount with the highest reliability.
- the selection unit 594 selects the first candidate, the second candidate, and the first candidate of the wideband carrier frequency error amount input from each of the maximum value detection unit 331, the maximum value detection unit 591U, and the maximum value detection unit 591G. 3 is selected as a broadband carrier frequency error amount candidate having the highest reliability from among the three candidates, and the selected broadband carrier frequency error amount candidate is used for correction. It outputs to the correction
- the complex multiplier 171, the arrangement correlation calculator 172, the power calculator 173, the maximum value detector 331, and the reliability detector 332 receive both the output signal from the orthogonal transform unit 153 ⁇ / b> U and the output signal from the orthogonal transform unit 153 ⁇ / b> G.
- This block is used to detect a first candidate for a wideband carrier frequency error amount and to execute a first detection process for detecting the reliability of the first candidate.
- the power calculation unit 211U, the arrangement correlation calculation unit 311U, the square calculation unit 571U, the maximum value detection unit 591U, and the reliability detection unit 592U are orthogonal among the output signal of the orthogonal transform unit 153U and the output signal of the orthogonal transform unit 153G.
- the power calculation unit 211G, the arrangement correlation calculation unit 311G, the square calculation unit 571G, the maximum value detection unit 591G, and the reliability detection unit 592G are orthogonal among the output signals of the orthogonal transformation unit 153U and the output signals of the orthogonal transformation unit 153G.
- wideband carrier frequency error not only in a multipath interference environment or a noise environment, but also in an environment where impulse noise locally exists in the previous guard interval period, the subsequent guard interval period, and the effective symbol period.
- the quantity can be estimated accurately.
- the OFDM receiving apparatus includes a P1 wideband fc error detection correction unit 600 that is different from the P1 wideband fc error detection correction unit 155 of the OFDM reception apparatus described in the first to ninth embodiments. Different from those OFDM receivers. However, the P1 wideband fc error detection / correction unit 600 selects and selects one of the output signal of the P1 orthogonal transform unit 153U and the output signal of the P1 orthogonal transform unit 153G with respect to the P1 wideband fc error detection correction unit 155 and the like. This is a function in which a function for correcting a wide band carrier frequency shift is added to a signal.
- FIG. 25 is a configuration diagram of the P1 broadband fc error detection correction unit 600. 25 also illustrates a P1 orthogonal transform unit 153U, a P1 orthogonal transform unit 153G, and a CDS table generation unit 154 in order to clarify the input to each unit of the P1 wideband fc error detection correction unit 600.
- the detection unit 610 includes a selection unit 312A instead of the selection determination unit 312 of the detection unit 310 of FIG.
- the selection unit 312A has the configuration shown in FIG. 26, and includes a determination unit 333A instead of the determination unit 333 of FIG.
- the determination unit 333A has the following function in addition to the function of the determination unit 333.
- the determination unit 333A includes the reliability of the first candidate, the reliability of the second candidate, and the third reliability of the wideband carrier frequency error amount input from each of the reliability detection unit 332, the reliability detection unit 332U, and the reliability detection unit 332G. Compare the reliability of the candidates. Then, the determination unit 333A notifies the selection unit 620 to select the output signal of the P1 orthogonal transform unit 153U and output it to the correction unit 180A when the reliability of the first candidate is the highest.
- the determination unit 333A notifies the selection unit 620 to select the output signal of the P1 orthogonal transform unit 153U and output it to the correction unit 180A. Furthermore, when the reliability of the third candidate is the highest, the determination unit 333A notifies the selection unit 620 to select the output signal of the P1 orthogonal transform unit 153G and output it to the correction unit 180A.
- the determination unit 333A compares the reliability of the second candidate and the reliability of the third candidate of the broadband carrier frequency error amount input from the reliability detection unit 332U and the reliability detection unit 332G, respectively. Then, when the reliability of the second candidate is higher, the determination unit 333A selects the output signal of the P1 orthogonal transform unit 153U and notifies the selection unit 620 to output it to the correction unit 180A. On the other hand, when the reliability of the third candidate is higher, the determination unit 333A selects the output signal of the P1 orthogonal transform unit 153G and notifies the selection unit 620 to output it to the correction unit 180A. Good.
- the selection unit 620 in FIG. 25 selects and selects one of the output signal of the first orthogonal transform unit 153U and the output signal of the second orthogonal transform unit 153G according to the notification from the determination unit 333A in the selection determination unit 312A.
- the signal is output to the correction unit 180A.
- the correction unit 180A corrects the shift of the wideband carrier frequency of the output signal (complex baseband signal in the frequency domain) of the selection unit 620 based on the wideband carrier frequency error amount output from the selection unit 334 in the selection determination unit 312A. To implement. Then, the correction unit 180A uses the active carrier arrangement sequence input from the CDS table generation unit 154 to extract only the active carrier from the complex baseband signal in the frequency domain in which the shift of the wideband carrier frequency is corrected. The extracted active carrier is output to the P1 decoding unit 156 in FIG. 4 (descramble unit 191 in FIG. 7). Note that the selection unit 334A in the selection unit 312A supplies the correction unit 180A with the broadband carrier frequency error amount of the signal in the frequency region of the effective symbol period.
- the signal of the coupling guard interval is a signal of the effective symbol section obtained by f SH partial frequency shift (1 those frequency shift as subcarriers frequency is increased). From this, when the output signal of the orthogonal transform unit 180G is selected by the selection unit 620, the correction unit 180A corrects the shift of the wideband carrier frequency by a value smaller than the supplied wideband carrier frequency error amount. It will be.
- the present embodiment it is possible to perform the P1 symbol decoding process using the signal having the higher reliability among the signal of the effective symbol period and the signal of the combined guard interval period, and the accuracy of decoding of the P1 symbol Can be improved.
- the present invention is not limited to the contents described in the above embodiment, and can be implemented in any form for achieving the object of the present invention and the object related thereto or incidental thereto. .
- the signal in the combined guard interval section is shifted to the high frequency side by one subcarrier with respect to the signal in the effective symbol section.
- the calculation using the above (Formula 16), the above (Formula 19), and the above (Formula 20) is performed.
- the present invention is not limited to this, and it is sufficient to consider that it is shifted to the high frequency side by one subcarrier. For example, the following may be used.
- a frequency shift correction unit is provided before the P1 orthogonal transform unit 153G, and the frequency shift correction unit shifts the frequency of the complex baseband signal in the time domain of the combined guard interval section of the P1 symbol by ⁇ f SH (guard interval).
- Correction processing related to the implementation of the frequency shift in the reverse direction that cancels out the frequency shift of f SH applied to the signal of the section by the amount of f SH ), and the frequency-shifted complex baseband signal in the time domain is P1 Output to the orthogonal transform unit 153G.
- a frequency shift correction unit is provided in the subsequent stage of the P1 orthogonal transform unit 153G, and this frequency shift correction unit is provided for the output signal of the P1 orthogonal transform unit 153G (complex baseband signal in the frequency domain of the combined guard interval section of P1 symbols). Correction so that the frequency is lowered by one subcarrier (correction processing for performing a frequency shift in the reverse direction that cancels out the frequency shift by f SH applied to the signal in the guard interval section on the transmission side) The complex baseband signal in the frequency domain corrected so that the frequency is lowered by one subcarrier is output to the P1 wideband fc error detection and correction unit 155G.
- the P1 orthogonal transform unit 153G performs a correction process of shifting the frequency by ⁇ f SH when performing the orthogonal transform.
- the complex multiplier 171 performs the operation shown in the following (Equation 21) instead of the above (Equation 16), and the multiplier 212 performs the following (Equation 19) instead of the above (Equation 19).
- the multiplication unit 272 may perform the calculation shown in the following (Equation 23) instead of the above (Equation 20).
- the complex multiplier 171 instead of the calculation of the above equation (21) is multiplied by a signal of the complex conjugate of the output signal Y U (n) Y U ( n) * and the output signal Y G (n) You may do it.
- the frequency shift correction unit described above performs correction processing (only ⁇ f X minutes) for performing a frequency shift in the reverse direction that cancels out frequency shifts by f X performed on the transmission side with respect to the signals in the guard interval section.
- the processing relating to the implementation of the frequency shift may be performed.
- the signal in the guard interval section is a frequency shift of the signal in the effective symbol section so that the frequency is lowered by ( ⁇ X) subcarriers.
- the complex multiplier 171 performs the operation shown in the following (Equation 24) instead of the above (Equation 16), and the multiplier 212 performs the operation shown in the following (Equation 25) instead of the above (Equation 19).
- the multiplication unit 272 may perform the calculation shown in the following (Equation 26) instead of the above (Equation 20).
- the signal in the guard interval section is a frequency shift of the signal in the effective symbol section so that the frequency is lowered by ( ⁇ X) subcarriers.
- the complex multiplier 17 instead of the calculation of the above equation (24), multiplies the output signal Y U signal of the complex conjugate of (n) Y U (n) * and the output signal Y G (n + X) You may do it.
- the division value (maximum value ⁇ second largest value) obtained by dividing the maximum value of the signal input to each reliability detection unit by the second largest value is trusted.
- the division value (second largest value ⁇ maximum value) obtained by dividing the second largest value by the maximum value of the signal input to each reliability detection unit may be the reliability, and the smaller the value, the higher the reliability may be.
- the maximum value of the signal input to each reliability detection unit may be the reliability, and the greater the value, the higher the reliability.
- the difference between the maximum value of the signal input to each reliability detection unit and the second largest value may be used as the reliability, and the higher the value, the higher the reliability.
- the first detection process, the second detection process, and the third detection process are performed.
- the present invention is not limited to this. Only two may be performed.
- Correction of wideband carrier frequency deviation is performed on a signal selected by selecting one of the output signal of the P1 orthogonal transform unit 153U and the output signal of the P1 orthogonal transform unit 153G described in the tenth embodiment.
- the function to be implemented may be applied to the wideband fc error detection correction units 350, 400, 450, 500, 550 described in the fifth to ninth embodiments.
- one orthogonal transform unit 106 or one P1 orthogonal transform unit 153U, 153G is provided for each orthogonal transform.
- the present invention is not limited to this. All or some of them may be shared.
- the narrow band carrier frequency error amount and the wide band carrier frequency error amount detected by each P1 demodulator are output to the fc correction unit 102, and the fc correction unit 102 These are used when correcting.
- the present invention is not limited to this, and the fc correction unit 102 performs one of the narrowband carrier frequency error amount and the wideband carrier frequency error amount detected by each P1 demodulation unit when correcting the shift of the carrier frequency. May be used alone, or none of them may be used.
- the narrowband fc error calculation unit 105 and the wideband fc error calculation unit 107 calculate the narrowband carrier frequency error amount and the wideband carrier frequency error amount in the P2 symbol and the data symbol, and the P1 narrowband fc error detection correction unit 152.
- the method of detecting the narrow-band carrier frequency error amount in the P1 symbol is not particularly limited, and a known method can be applied.
- the narrowband carrier frequency error amount may be calculated from the phase difference between the pilot signal symbols included in the P2 symbol or the data symbol for the output signal of the orthogonal transform unit 106.
- an OFDM receiver conforming to the DVB-T2 transmission standard has been described.
- the present invention is not limited to this.
- an FEF period in the DVB-T2 transmission standard is used. Since the P1 symbol is inserted at the beginning of the FEF period in the transmission standard, the present invention can also be applied to an OFDM receiver that complies with the transmission standard using the FEF period.
- the signal of the guard interval is not intended to be limited signal of the effective symbol period to f SH partial frequency shifted signal may be a signal not frequency-shifted signal of the effective symbol section, f SH It may be a frequency shifted signal other than the fractional frequency shift.
- the signal in the guard interval section is not limited to the signal obtained by frequency-shifting the entire signal in the effective symbol section, but a part of the signal in the effective symbol section is frequency-shifted and the remaining part is frequency-shifted. There may be no signal.
- the guard interval section is not limited to the one divided into the previous guard interval section and the rear guard interval section, and may consist of only the previous guard interval section or only the rear guard interval section. It may be. Note that the guard interval section may be divided into three or more. For example, the effective symbol section may be divided and the divided section of the guard interval section may be inserted therebetween.
- the time width of the guard interval section is not limited to the time width of the effective symbol section, and may be different.
- the FFT size is 1k, but the present invention is not limited to this, and the FFT size may be other than 1k (for example, 2k, 4k, 8k, etc.).
- the differential demodulation is demodulation corresponding to DBPSK.
- DBPSK Downlink Physical Broadcasting
- DQPSK Downlink Physical Signals Keying
- Demodulation corresponding to modulation may be used.
- differential demodulation is described as an example. However, demodulation other than differential demodulation may be used.
- Each component of the receiving device in each of the above embodiments may be realized by an LSI which is an integrated circuit. At this time, each component may be individually made into one chip, or may be made into one chip so as to include a part or all of them. Further, although it is referred to as LSI here, it may be referred to as IC, system LSI, super LSI, or ultra LSI depending on the degree of integration. Further, the method of circuit integration is not limited to LSI, and implementation with a dedicated circuit or a general-purpose processor is also possible. Further, the method of circuit integration is not limited to LSI, but may be realized by a dedicated circuit or a general-purpose processor.
- An FPGA Field Programmable Gate Array
- a reconfigurable processor capable of reconfiguring connection and setting of circuit cells inside the LSI may be used. Furthermore, if integrated circuit technology comes out to replace LSI's as a result of the advancement of semiconductor technology or a derivative other technology, it is naturally also possible to carry out function block integration using this technology. Possible applications include biotechnology.
- At least a part of the operation procedure of the receiving apparatus described in each of the above embodiments is described in the reception program, and for example, a CPU (Central Processing Unit) reads and executes the program stored in the memory.
- the program may be stored in a recording medium and distributed.
- a reception device that performs at least a part of the reception processing of the reception device described in each of the above embodiments may be realized.
- any of the above-described embodiments may be realized by combining any receiving device, receiving method, receiving circuit, or program that performs a part of the receiving process for realizing each of the above-described embodiments.
- a part of the configuration of the receiving device described in each of the above embodiments is realized by the receiving device or the integrated circuit, and an operation procedure performed by the configuration excluding the part is described in the receiving program. It may be realized by reading out and executing the program stored in.
- the present invention can be used for an OFDM receiving apparatus that receives an OFDM symbol composed of a signal in an effective symbol period and a signal in a guard interval period based on the signal in the effective symbol period.
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Abstract
Description
以下、本発明の第1の実施の形態に係るOFDM受信装置1について、図面を参照しつつ説明する。但し、第1の実施の形態及び後述する各実施の形態では、第二世代の欧州地上デジタル放送規格であるDVB-T2方式に準拠したデジタル放送の受像機として動作するOFDM受信装置を例に挙げて説明を行う。なお、OFDM受信装置1が受信する受信信号は、DVB-T2伝送フォーマットに則ったOFDMシンボルから構成されるOFDM信号である。
以下、本発明の第2の実施の形態について図面を参照しつつ説明する。但し、本実施の形態において、第1の実施の形態の構成要素と実質的に同じ構成要素には同じ符号を付し、その説明が適用できるため、本実施の形態ではその説明を省略する。
以下、本発明の第3の実施の形態について図面を参照しつつ説明する。但し、本実施の形態において、第1から第2の実施の形態の構成要素と実質的に同じ構成要素には同じ符号を付し、その説明が適用できるため、本実施の形態ではその説明を省略する。
以下、本発明の第4の実施の形態について図面を参照しつつ説明する。但し、本実施の形態において、第1から第3の実施の形態の構成要素と実質的に同じ構成要素には同じ符号を付し、その説明が適用できるため、本実施の形態ではその説明を省略する。
以下、本発明の第5の実施の形態について図面を参照しつつ説明する。但し、本実施の形態において、第1から第4の実施の形態の構成要素と実質的に同じ構成要素には同じ符号を付し、その説明が適用できるため、本実施の形態ではその説明を省略する。
以下、本発明の第6の実施の形態について図面を参照しつつ説明する。但し、本実施の形態において、第1から第5の実施の形態の構成要素と実質的に同じ構成要素には同じ符号を付し、その説明が適用できるため、本実施の形態ではその説明を省略する。
以下、本発明の第7の実施の形態について図面を参照しつつ説明する。但し、本実施の形態において、第1から第6の実施の形態の構成要素と実質的に同じ構成要素には同じ符号を付し、その説明が適用できるため、本実施の形態ではその説明を省略する。
以下、本発明の第8の実施の形態について図面を参照しつつ説明する。但し、本実施の形態において、第1から第7の実施の形態の構成要素と実質的に同じ構成要素には同じ符号を付し、その説明が適用できるため、本実施の形態ではその説明を省略する。
以下、本発明の第9の実施の形態について図面を参照しつつ説明する。但し、本実施の形態において、第1から第8の実施の形態の構成要素と実質的に同じ構成要素には同じ符号を付し、その説明が適用できるため、本実施の形態ではその説明を省略する。
以下、本発明の第10の実施の形態について図面を参照しつつ説明する。但し、本実施の形態において、第1から第9の実施の形態の構成要素と実質的に同じ構成要素には同じ符号を付し、その説明が適用できるため、本実施の形態ではその説明を省略する。
本発明は上記の実施の形態で説明した内容に限定されず、本発明の目的とそれに関連又は付随する目的を達成するためのいかなる形態においても実施可能であり、例えば、以下であってもよい。
103 P1復調部
151 P1位置検出部
152 P1狭帯域fc誤差検出補正部
153U P1直交変換部
153G P1直交変換部
154 CDSテーブル生成部
155 P1広帯域fc誤差検出補正部
170 検出部
171 複素乗算部
172 配置相関部
173 電力算出部
174 最大値検出部
180 補正部
Claims (17)
- 有効シンボル区間の信号と、当該有効シンボル区間の信号に基づくガードインターバル区間の信号とから構成されたOFDMシンボルを受信するOFDM受信装置であって、
前記有効シンボル区間の信号を直交変換し、直交変換の結果を出力する第1直交変換部と、
前記ガードインターバル区間の信号を直交変換し、直交変換の結果を出力する第2直交変換部と、
前記第1直交変換部の出力信号と前記第2直交変換部の出力信号とに基づいて前記OFDMシンボルの広帯域キャリア周波数誤差量を検出する検出部と、
前記検出部により検出された広帯域キャリア周波数誤差量に基づいて前記OFDMシンボルの広帯域キャリア周波数のずれの補正を実施する補正部と、
を備えるOFDM受信装置。 - 前記ガードインターバル区間の信号は、前記有効シンボル区間の信号を周波数シフトしたものである
請求項1記載のOFDM受信装置。 - 前記第2直交変換部の入力信号又は前記第2直交変換部の出力信号に対して前記周波数シフトを相殺する逆方向の周波数シフトの実施に係る補正処理を前記第2直交変換部の前段又は後段において実施し、補正処理の結果を出力する周波数シフト補正部
を更に備え、
前記検出部は、前記広帯域キャリア周波数のずれの補正を、前記第1直交変換部の出力信号と、前記周波数シフト補正部の出力信号を直交変換して得られた前記第2直交変換部の出力信号又は前記周波数シフト補正部の出力信号と、に基づいて行う
請求項2記載のOFDM受信装置。 - 前記OFDMシンボルは、DVB-T2伝送方式におけるP1シンボルであり、
前記ガードインターバル区間は、前記有効シンボル区間より手前の前ガードインターバル区間と、前記有効シンボル区間より後ろの後ガードインターバル区間とからなり、
前記第2直交変換部は、前記直交変換を、前記前ガードインターバル区間の信号と前記後ガードインターバル区間の信号とを結合した信号を用いて行う
請求項1記載のOFDM受信装置。 - 前記OFDMシンボルを構成する複数のサブキャリアは、複数のActiveキャリアと複数のNullキャリアとで構成されており、
前記複数のActiveキャリアの各々が配置されるサブキャリア位置は、所定の配置パターンによって規定されており、
前記検出部は、
前記第1直交変換部の出力信号と前記第2直交変換部の出力信号とに基づく信号の連続する複数のサブキャリアにおいて前記配置パターンで規定された複数のActiveキャリアの位置に対応するサブキャリアでの当該信号の値を加算する加算処理を、前記連続する複数のサブキャリアを所定の範囲内でサブキャリア方向に1サブキャリア単位で順次シフトしながら実施し、加算処理の結果に基づいて、前記広帯域キャリア周波数誤差量を検出する
請求項1記載のOFDM受信装置。 - 前記検出部は、
前記第1直交変換部の出力信号と前記第2直交変換部の出力信号との複素乗算をサブキャリア毎に実施する複素乗算部と、
連続する複数のサブキャリアにおいて前記配置パターンで規定された複数のActiveキャリアの位置に対応するサブキャリアでの複素乗算値を加算する加算処理を、前記連続する複数のサブキャリアを所定の範囲内でサブキャリア方向に1サブキャリア単位で順次シフトしながら実施して加算処理の結果を出力する加算処理部と、
前記加算処理部の各出力信号の電力を算出し、算出結果を出力する電力算出部と、
前記電力算出部の各出力信号の中から最大値を検出することによって前記広帯域キャリア周波数誤差量を検出する最大値検出部と、
を備える請求項5記載のOFDM受信装置。 - 前記検出部は、
前記第1直交変換部の出力信号の電力をサブキャリア毎に算出し、算出結果を出力する第1電力算出部と、
前記第2直交変換部の出力信号の電力をサブキャリア毎に算出し、算出結果を出力する第2電力算出部と、
前記第1電力算出部の出力信号と前記第2電力算出部の出力信号との乗算をサブキャリア毎に実施する乗算部と、
連続する複数のサブキャリアにおいて前記配置パターンで規定された複数のActiveキャリアの位置に対応するサブキャリアでの乗算値を加算する加算処理を、前記連続する複数のサブキャリアを所定の範囲内でサブキャリア方向に1サブキャリア単位で順次シフトしながら実施して加算処理の結果を出力する加算処理部と、
前記加算処理部の各出力信号の中から最大値を検出することによって前記広帯域キャリア周波数誤差量を検出する最大値検出部と、
を備える請求項5記載のOFDM受信装置。 - 前記検出部は、
前記第1直交変換部の出力信号の振幅をサブキャリア毎に算出し、算出結果を出力する第1振幅算出部と、
前記第2直交変換部の出力信号の振幅をサブキャリア毎に算出し、算出結果を出力する第2振幅算出部と、
前記第1振幅算出部の出力信号と前記第2振幅算出部の出力信号との乗算をサブキャリア毎に実施する乗算部と、
連続する複数のサブキャリアにおいて前記配置パターンで規定された複数のActiveキャリアの位置に対応するサブキャリアでの乗算値を加算する加算処理を、前記連続する複数のサブキャリアを所定の範囲内でサブキャリア方向に1サブキャリア単位で順次シフトしながら実施して加算処理の結果を出力する加算処理部と、
前記加算処理部の各出力信号の中から最大値を検出することによって前記広帯域キャリア周波数誤差量を検出する最大値検出部と、
を備える請求項5記載のOFDM受信装置。 - 前記OFDMシンボルを構成する複数のサブキャリアは、複数のActiveキャリアと複数のNullキャリアとで構成されており、
前記複数のActiveキャリアの各々が配置されるサブキャリア位置は、所定の配置パターンによって規定されており、
前記検出部は、
前記第1直交変換部の出力信号と前記第2直交変換部の出力信号との双方を用いて広帯域キャリア周波数誤差量の第1候補を検出し、前記第1候補の信頼度を検出する第1検出処理、
前記第1直交変換部の出力信号及び前記第2直交変換部の出力信号のうちの前記第1直交変換部の出力信号のみを用いて広帯域キャリア周波数誤差量の第2候補を検出し、前記第2候補の信頼度を検出する第2検出処理、及び、
前記第1直交変換部の出力信号及び前記第2直交変換部の出力信号のうちの前記第2直交変換部の出力信号のみを用いて広帯域キャリア周波数誤差量の第3候補を検出し、前記第3候補の信頼度を検出する第3検出処理、の少なくとも2つを実施し、
信頼度が最も高い広帯域キャリア周波数誤差量の候補を前記補正部が用いる前記広帯域キャリア周波数誤差量として選択する
請求項1記載のOFDM受信装置。 - 前記検出部は、
前記第1検出処理を、
前記第1直交変換部の出力信号と前記第2直交変換部の出力信号とに基づく第1信号の連続する複数のサブキャリアにおいて前記配置パターンで規定された複数のActiveキャリアの位置に対応するサブキャリアでの当該第1信号の値を加算する加算処理を、前記連続する複数のサブキャリアを所定の範囲内でサブキャリア方向に1サブキャリア単位で順次シフトしながら実施し、加算処理の結果に基づいて前記広帯域キャリア周波数誤差量の第1候補及び前記第1候補の信頼度を検出することによって実施し、
前記第2検出処理を、
前記第1直交変換部の出力信号に基づく第2信号の連続する複数のサブキャリアにおいて前記配置パターンで規定された複数のActiveキャリアの位置に対応するサブキャリアでの当該第2信号の値を加算する加算処理を、前記連続する複数のサブキャリアを所定の範囲内でサブキャリア方向に1サブキャリア単位で順次シフトしながら実施し、加算処理の結果に基づいて前記広帯域キャリア周波数誤差量の第2候補及び前記第2候補の信頼度を検出することによって実施し、
前記第3検出処理を、
前記第2直交変換部の出力信号に基づく第3信号の連続する複数のサブキャリアにおいて前記配置パターンで規定された複数のActiveキャリアの位置に対応するサブキャリアでの当該第3信号の値を加算する加算処理を、前記連続する複数のサブキャリアを所定の範囲内でサブキャリア方向に1サブキャリア単位で順次シフトしながら実施し、加算処理の結果に基づいて前記広帯域キャリア周波数誤差量の第3候補及び前記第3候補の信頼度を検出することによって実施する
請求項9記載のOFDM受信装置。 - 前記第1から第3の各信頼度は前記加算処理の結果の最大値を2番目に大きい値で除算した値であって値が大きい程信頼度が高い、又は、前記第1から第3の各信頼度は前記加算処理の結果の最大値で2番目に大きい値を除算した値であって値が小さい程信頼度が高い
請求項10記載のOFDM受信装置。 - 前記第1から第3の各信頼度は前記加算処理の結果の最大値であって値が大きい程信頼度が高い
請求項10記載のOFDM受信装置。 - 前記第1から第3の各信頼度は前記加算処理の結果の最大値と2番目に大きい値との差であって値が大きい程信頼度が高い
請求項10記載のOFDM受信装置。 - 検出された前記各候補の信頼度に基づいて、前記有効シンボル区間の信号と前記ガードインターバル区間の信号の一方を選択し、選択した信号を前記補正部へ出力する選択部を更に備え、
前記補正部は、前記選択部から入力された信号に対して前記広帯域キャリア周波数ずれの補正を実施する
請求項10記載のOFDM受信装置。 - 有効シンボル区間の信号と、当該有効シンボル区間の信号に基づくガードインターバル区間の信号とから構成されたOFDMシンボルを受信するOFDM受信回路であって、
前記有効シンボル区間の信号を直交変換し、直交変換の結果を出力する第1直交変換回路と、
前記ガードインターバル区間の信号を直交変換し、直交変換の結果を出力する第2直交変換回路と、
前記第1直交変換回路の出力信号と前記第2直交変換回路の出力信号とに基づいて前記OFDMシンボルの広帯域キャリア周波数誤差量を検出する検出回路と、
前記検出回路により検出された広帯域キャリア周波数誤差量に基づいて前記OFDMシンボルの広帯域キャリア周波数のずれの補正を実施する補正回路と、
を備えるOFDM受信回路。 - 有効シンボル区間の信号と、当該有効シンボル区間の信号に基づくガードインターバル区間の信号とから構成されたOFDMシンボルを受信するOFDM受信装置において行われるOFDM受信方法であって、
前記有効シンボル区間の信号を直交変換する第1直交変換ステップと、
前記ガードインターバル区間の信号を直交変換する第2直交変換ステップと、
前記第1直交変換ステップでの直交変換の結果と前記第2直交変換ステップでの直交変換の結果とに基づいて前記OFDMシンボルの広帯域キャリア周波数誤差量を検出する検出ステップと、
前記検出ステップで検出された広帯域キャリア周波数誤差量に基づいて前記OFDMシンボルの広帯域キャリア周波数のずれの補正を実施する補正ステップと、
を備えるOFDM受信方法。 - 有効シンボル区間の信号と、当該有効シンボル区間の信号に基づくガードインターバル区間の信号とから構成されたOFDMシンボルを受信するOFDM受信装置に、
前記有効シンボル区間の信号を直交変換する第1直交変換ステップと、
前記ガードインターバル区間の信号を直交変換する第2直交変換ステップと、
前記第1直交変換ステップでの直交変換の結果と前記第2直交変換ステップでの直交変換の結果とに基づいて前記OFDMシンボルの広帯域キャリア周波数誤差量を検出する検出ステップと、
前記検出ステップで検出された広帯域キャリア周波数誤差量に基づいて前記OFDMシンボルの広帯域キャリア周波数のずれの補正を実施する補正ステップと、
を実行させるOFDM受信プログラム。
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