KR101209501B1 - Receiver - Google Patents
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- KR101209501B1 KR101209501B1 KR1020107023983A KR20107023983A KR101209501B1 KR 101209501 B1 KR101209501 B1 KR 101209501B1 KR 1020107023983 A KR1020107023983 A KR 1020107023983A KR 20107023983 A KR20107023983 A KR 20107023983A KR 101209501 B1 KR101209501 B1 KR 101209501B1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
- H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
- H04L27/3488—Multiresolution systems
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/0014—Carrier regulation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/0014—Carrier regulation
- H04L2027/0044—Control loops for carrier regulation
- H04L2027/0063—Elements of loops
- H04L2027/0067—Phase error detectors
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- Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
Abstract
The receiver 10 includes a multi-level modulation method determination circuit 16, a phase correction method selection circuit 17, a phase correction circuit 14, and a determination circuit 15. The multi-level modulation scheme determination circuit 16 determines the multi-level modulation scheme used for the modulated signal according to the modulated signal received from the transmitter. The phase correction method selection circuit 17 predetermines the phase correction method used for phase correction of symbols of the modulated signal based on the multi-level class of the multi-level modulation method determined by the multi-level modulation method determination circuit 16. Select from a plurality of phase correction schemes. The phase correction circuit 14 corrects the phase of a symbol using the phase correction method selected by the phase correction method selection circuit 17. The determination circuit 15 determines the bit sequence of the phase-corrected symbol by the phase correction circuit 14 based on the multi-level modulation scheme determined by the multi-level modulation scheme determination circuit 16.
Description
The present invention relates to a receiver, in particular a receiver for use in a communication system using an adaptive modulation scheme.
Conventionally, there is a communication system using an adaptive modulation scheme. This communication system has a plurality of multi-level modulation schemes having different multi-level classes (bit rates), and switches, for example, the multi-level modulation scheme to be used depending on the environment (line quality) surrounding the self. In this case, the best transmission efficiency can be obtained based on the line quality. Here, as the multi-level modulation method, there are, for example, Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), 16 Quadrature Amplitude Modulation (QAM), 64 QAM, etc. in order from a low bit rate method. (See, for example, Japanese Laid-Open Patent Publication 2007-150906, IEEE 802.11a-1999).
However, each of the transmitter and the receiver constituting the communication system has a reference signal source. The reference signal source uses a crystal transmitter. The oscillation frequency (hereinafter referred to as " reference frequency ") of each reference signal source of the transmitter and receiver includes an error due to the precision of the crystal transmitter. As a result, an error of about ppm occurs between the reference frequency of the transmitter side performing modulation processing and the reference frequency of the receiver side performing demodulation processing. This error in the reference frequency is caused by the phase rotation of the data received by the receiver. The occurrence of such phase rotation greatly affects the bit error rate (hereinafter, referred to as "BER") after demodulation. Therefore, at the time of demodulation, the receiver corrects phase rotation of the received data. In particular, in the case of multi-level modulation using a multicarrier modulation scheme such as orthogonal frequency division multiplexing (OFDM) modulation, the influence of phase rotation due to frequency error during demodulation is increased. This is because the occupancy time of a single symbol increases, and the interval of phase correction becomes long.
Conventionally, as a phase correction method for correcting the phase rotation of a symbol, a phase correction method using a pilot subcarrier (for example, see Japanese Laid-Open Patent Publication No. 2008-22339), or a phase correction method using a pilot symbol (example For example, see Japanese Laid-Open Patent Publication 2006-352746.
In the phase correction method using the pilot subcarrier, when large frequency selectivity exists in the propagation characteristic of a signal under the influence of multipath paging, a correction error becomes large.
Therefore, in a radio wave environment with strong frequency selectivity, a phase correction method using a pilot symbol is effective.
On the other hand, the phase correction method using a pilot symbol is not a sequential correction for each OFDM symbol, unlike the phase correction method using a pilot subcarrier. Therefore, the interval at which the pilot symbol is embedded in the modulated signal must be narrowed as the multilevel class of the multilevel modulation scheme increases. Therefore, if the adaptive modulation scheme can perform satisfactory phase correction for all the multilevel modulation schemes, the transmission efficiency is lowered, particularly in the low multilevel modulation scheme of the multilevel class.
In addition, phase correction using a pilot symbol cannot be phase corrected until a pilot symbol is obtained, so phase correction is performed and the interval is relatively long. Therefore, in the case of the multi-level modulation system of high multi level class, there is a fear that the error of phase rotation exceeds the allowable range during the demodulation process.
In this manner, the multilevel modulation method cannot be applied to the phase correction method. However, conventional receivers use the same phase correction scheme for modulated signals received from a transmitter. Therefore, the conventional receiver cannot perform optimal phase correction in accordance with the multi-level modulation scheme performed by the transmitter.
This invention is made | formed in view of the said reason. It is an object of the present invention to provide a receiver capable of performing optimal phase correction in accordance with a multi-level modulation scheme performed by a transmitter.
The receiver according to the present invention is used in an adaptive modulation communication system related to a transmitter for transmitting a modulation signal generated using a multi-level modulation scheme selected from a plurality of multi-level modulation schemes according to line quality. The modulated signal has a symbol sequence representing data to be transmitted to the receiver. The symbol has a corresponding relationship with a bit sequence by a multi-level modulation scheme selected by the transmitter. The receiver according to the present invention includes a multi-level modulation method determination unit, a phase correction method selection unit, a phase correction unit, and a determination unit. The multilevel modulation scheme determination unit is configured to determine the multilevel modulation scheme used for the modulation signal in accordance with the modulation signal received from the transmitter. The phase correction method selection unit includes a plurality of predetermined phase correction methods used for correcting a phase of a symbol of the modulated signal based on the multi-level class of the multi-level modulation method determined by the multi-level modulation method determination unit. It is configured to select from the phase correction scheme of. The phase correction unit is configured to correct the phase of the symbol by using the phase correction method selected by the phase correction method selection unit. The determination unit is configured to determine a bit sequence corresponding to the symbol whose phase has been corrected by the phase correction unit based on the multi-level modulation method determined by the modulation method determination unit.
According to the present invention, a phase correction scheme is selected based on the multi-level class of the multi-level modulation scheme performed by the transmitter. Therefore, optimal phase correction can be performed according to the multi-level modulation scheme performed by the transmitter.
Preferably, the transmitter has a primary modulation scheme and a secondary modulation scheme. The primary modulation scheme is a multilevel modulation scheme selected by a predetermined criterion from a plurality of multilevel modulation schemes having different multilevel classes, and generates a primary modulation symbol representing the symbol. The secondary modulation scheme is a multicarrier modulation scheme. In the second modulation scheme, a second modulation symbol is generated by multiplexing a plurality of subcarriers having a complex amplitude based on the first modulation symbol. The secondary modulation scheme constitutes the modulated signal composed of a plurality of the secondary modulation symbols. The modulated signal includes a pilot symbol for each predetermined regular interval. The pilot symbol is an existing secondary modulation symbol specific to the receiver. The predetermined secondary modulation symbol is composed of subcarriers having a predetermined complex amplitude. The secondary modulation symbol includes a pilot subcarrier. The pilot subcarrier is a predetermined subcarrier specific to the receiver. The predetermined subcarrier has a predetermined complex amplitude. The phase correction method selection unit is configured to correct the phase of the symbol by using the pilot symbols when the multi level class of the multi level modulation method determined by the multi level modulation method determination unit is less than a predetermined value. Select a first phase correction scheme and select a second phase correction scheme to correct the phase of the symbol using the pilot subcarrier if the multi-level class is greater than or equal to a predetermined value.
In this case, when the multi-level class of the multi-level modulation scheme performed by the transmitter is less than a predetermined value, phase correction using the pilot symbol having a large phase correction effect is performed even in a radio wave environment having high frequency selectivity. On the other hand, when the multi-level class of the multi-level modulation scheme performed by the transmitter is equal to or greater than a predetermined value, phase correction using the pilot subcarrier that realizes high transmission efficiency and is cheap is performed. Therefore, optimal phase correction can be performed according to the multi-level modulation scheme performed by the transmitter.
More preferably, the phase correction scheme selection unit selects the report of the first phase correction scheme if the multi-level grade of the multi-level modulation scheme determined by the multi-level modulation scheme determination unit is less than a predetermined value. And select both of the first phase correction scheme and the second phase correction scheme if the multi-level grade is equal to or greater than a predetermined value.
In this case, the first phase correction using the pilot symbol is always performed. Therefore, the control of the phase correction unit is simplified. Further, in the first phase correction method, phase correction is performed for each subcarrier. Therefore, even in a radio wave environment with strong frequency selectivity, the effect of phase correction can always be increased.
More preferably, the phase correction unit is configured to perform the symbol according to the second phase correction method when both of the first phase correction method and the second phase correction method are selected by the phase correction method selection unit. And corrects the phase of the symbol according to the first phase correction scheme.
In this case, phase correction can be performed for each symbol by using a pilot subcarrier. In addition, an error caused by phase correction using a pilot subcarrier can be eliminated by phase correction using a pilot symbol. Therefore, optimal phase correction can be performed for a multilevel modulation method having a large multilevel class.
Preferably, the predetermined value is set based on the transmission efficiency when the phase correction unit corrects the phase of the symbol by using the phase correction method selected by the phase correction method selection unit.
In this case, the optimum phase correction can be performed according to the multi-level modulation scheme performed by the transmitter, and the transmission efficiency can be improved.
1 is a schematic diagram of a receiver of a first embodiment.
2 is a schematic diagram of a communication system having the receiver.
3 is an explanatory diagram of a well studio distribution of 16 QAM.
4 is an explanatory diagram of arrangement of subcarriers and pilot subcarriers.
5 is an explanatory diagram of a structure of an OFDM signal.
6 is an explanatory diagram of a buried structure of a pilot symbol.
7 is a schematic diagram of a receiver of the second embodiment.
(First embodiment)
As shown in FIG. 2, the
The
Here, the
The
In this way, the
Here, in a multi-level modulation system of high multi level class such as 64 QAM, the tolerance angle when determining the bit sequence of a symbol using a complex symbol on a complex plane is small. Therefore, it is necessary to perform phase correction for each symbol. Hereinafter, the tolerance error angle in QAM will be described taking 16 QAM as an example.
FIG. 3 shows the symbol arrangement (signal point arrangement) on the complex plane for the bit sequences [0000)] to [1111] of 16 QAM, assuming gray codes. The dividing line L1 in FIG. 3 passes through the midpoint of the line segment connecting the bit sequence [1110] and each symbol point of the bit sequence [1010] in the direction of the quadrature-phase (Q) axis. The dividing line L2 passes through the midpoint of the line segment connecting between the bit sequence [1010] and each symbol point of the bit sequence [1011] in the I-in-phase axis direction. When the complex symbol received by the
The complex symbol corresponding to the bit sequence [1010] received by the
Table 1 shows the tolerance angle θ1 of typical QAM. As is apparent from Table 1, as the multi-level rating increases, the tolerance angle θ1 decreases.
Next, in OFDM modulation, the phase rotation per OFDM symbol due to the error of the reference frequency is examined. As a factor of the phase error by phase rotation of an OFDM symbol, the error (first error) at the carrier frequency synchronization (frequency conversion) required for the demodulation process of OFDM, and the error (second error) at the sampling frequency synchronization (fast Fourier transform) Two) are considered. The occupancy time Ta per OFDM symbol is expressed by the following equation (1) when the sample frequency of the fast Fourier transform is fs, the size (FFT size) of the fast Fourier transform is N point, and the time of the guard interval is Tgi. .
(Equation 1)
The phase error due to the first error and the second error is additive. Therefore, if the carrier frequency is fc, and the reference frequency error between the reference frequencies used in modulation and demodulation is e, the phase error angle θ2 per OFDM symbol is expressed by the following equation (2).
(Equation 2)
For example, according to the IEEE 802.11a-1999 specification (the IEEE 802.11a standard of the wireless LAN defined by the Institute of Electrical and Electronics Engineers of the IEEE), if the reference frequency error of each reference signal source is 20 ppm, the amount of modulation and demodulation is processed. This results in a reference frequency error e of 40 ppm. The error of the carrier frequency fc is generally converged to a frequency error of fs / 2 by the automatic frequency correction circuit of the receiver. Therefore, Formula (2) can be transformed into following Formula (3).
(Equation 3)
According to the IEEE 802.11a-1999 specification, the sample frequency fs of the fast Fourier transform is 20 MHz, the occupancy time Ta of the OFDM symbol is 4 μsec (where the guard interval time Tgi is 0.8 μsec), and the size of the fast Fourier transform is 64. Is the point.
If equation (3) is calculated according to the specifications of IEEE 802.11a-1999, the phase error angle θ2 is 2.88. Therefore, at 64 QAM, the tolerance exceeds θ1 with four symbols. According to the IEEE 802.11a-1999 specification, one packet is required to be a maximum of 1000 bytes. Therefore, without adding redundant bits due to error correction, an OFDM symbol that can be transmitted in one packet becomes about 27 symbols. Therefore, when four tolerances exceed the tolerance angle θ1, one packet cannot be demodulated correctly.
Therefore, in IEEE 802.11a-1999, as shown in Fig. 4, four out of all 52 subcarriers are pilot subcarriers PSC1 to PSC4 irrelevant to data transmission, and the remaining 48 subcarriers SC0 to are used for data transmission. It is prescribed to be SC47. Therefore, phase correction for each OFDM symbol can be performed using the pilot subcarriers PSC1 to PSC4.
However, when there is a large frequency selectivity in the propagation characteristics of the signal due to the multipath paging, the S / N ratio of the frequency in which the pilot subcarriers are embedded may be extremely deteriorated. In this case, the correction error of the phase correction method using the pilot subcarrier becomes large. Therefore, especially in a high level multilevel modulation system, BER may be worsened by performing phase correction. For example, in FIG. 4, since the frequency characteristic 1000 deteriorates near the pilot subcarrier PSC1, the precision of phase correction using pilot subcarrier PSC1 falls.
In a propagation environment with high frequency selectivity, a phase correction method using pilot symbols is effective. The pilot symbol consists of predetermined symbols on both the
However, the phase correction scheme using pilot symbols is not a sequential correction for each OFDM symbol. Therefore, the interval at which the pilot symbol is embedded in the modulated signal must be narrowed as the multilevel class of the multilevel modulation scheme increases. For example, in 16 QAM, it is sufficient to embed pilot symbols in the modulated signal every 5 symbols. In contrast, in the 64 QAM, an interval at which pilot symbols are embedded in a modulated signal must be set every three symbols. Therefore, if the adaptive modulation system can perform satisfactory phase correction for all the multi-level modulation methods, the transmission efficiency is degraded, particularly in the low multi-level modulation method of the multi-level class.
In addition, since phase correction cannot be performed until the pilot symbol is obtained, the phase correction using the pilot symbol has a relatively long interval between phase corrections. Therefore, in the case of a multi-level modulation system of a high multi-level class, there is a fear of exceeding the tolerance angle θ1 during the demodulation process.
Thus, the
For example, a modulated signal (packet) is composed of a short preamble SP, a long preamble LP, and a data section D, as shown in FIG.
In order to establish symbol timing synchronization, the short preamble SP performs 10 times (X1 to X10) of the existing synchronization pattern (specific pattern) X for each basic period T1 (= 0.8 μsec) for the
The long preamble LP is configured by repeating the existing synchronization pattern Y twice (Y1, Y2) every basic period T2 (= 3.2 μsec) for the
The data portion D is an area for data transmission in which data bits, modulation scheme information, and the like are stored.
In the modulated signal, the short preamble SP, the long preamble LP, and the data portion D are arranged in the order of the short preamble SP, the long preamble LP, and the data portion D.
At the beginning of each region of the long preamble LP and the data portion D, guard intervals GI1 and GI2 in which a part of the latter half of each region is copied are added. According to the card intervals GI1 and GI2, the influence of the multipath can be reduced.
As shown in FIG. 1, the
After the analog-to-digital conversion (AD conversion) of the baseband signal, the automatic
The automatic
Next, the automatic
The automatic
The guard
The fast
The
The
The
In this manner, the
In the present embodiment, as shown in Fig. 4, four out of 52 subcarriers are pilot subcarriers PSC1 to PSC4 irrelevant to data transmission, and the remaining 48 are subcarriers SC0 to SC47 used for data transmission. The symbols on the pilot subcarriers PSC1 to PSC4 are existing data (predetermined symbols).
The phase
In this manner, the phase
The modulation
The correction
The
The
The phase error angle θ2 per OFDM symbol is 2.88 ° as described above. Table 2 shows the values of θ1 / θ2 in each of the multi-level modulation systems of QPSK, 16 QAM, and 64 QAM. In addition, Table 2 shows the minimum symbol interval M (maximum positive integer not exceeding [theta] 1 / [theta] 2) in which the pilot symbol is embedded in the modulated signal so as not to exceed the allowable error angle [theta] 1 during the demodulation process. In addition, Table 2 shows transmission efficiency P1 = M / (M + 1) when the pilot symbol is embedded in the modulated signal at the minimum symbol interval M. FIG.
As shown in Fig. 6, in each multi-level modulation method, the pilot symbol PS is embedded in the modulated signal for every M symbols. This prevents the phase error from exceeding the allowable error angle θ1 during the demodulation process. In addition, the transmission efficiency is the highest.
In the first phase correction scheme using the pilot symbol, the correction interval is longer than when using the pilot subcarrier. This is because each equalization parameter M symbols of the
On the other hand, the second phase correction method using the pilot subcarriers PSC1 to PSC4 is sequential correction for each OFDM symbol. Therefore, optimal phase correction can be performed for each OFDM symbol (for each complex symbol that is discrete Fourier transformed from the same OFDM symbol). Therefore, even in a multi-level modulation system of a high multi-level class, it is possible to prevent the phase error from exceeding the tolerance error angle θ1 during the demodulation process.
In the first phase correction scheme, it is necessary to shorten the interval between pilot symbols embedded in the modulated signal as the multi-level class increases. Therefore, transmission efficiency tends to be relatively low. As shown in Table 2, the transmission efficiency P1 becomes P1 = 0.83 at 16 QAM and P1 = 0.75 at 64 QAM. On the other hand, in the second phase correction method, four out of 52 subcarriers are used for the pilot subcarriers PSC1 to PSC4. Therefore, the transmission efficiency P2 when the pilot subcarrier is used is 0.92 = (48/52). Thus, the second phase correction scheme realizes higher transmission efficiency than the first phase correction scheme.
As described above, according to the
In particular, when the multi-level class of the multi-level modulation scheme performed by the
By the way, the phase correction
In this case, phase correction using pilot symbols is always performed. Therefore, the control of the
By the way, the
On the other hand, the phase
Therefore, when the impulse response is updated only by the phase
Therefore, when the multi-level class of the multi-level modulation method determined by the multi-level modulation
In this way, phase correction can be performed for each OFDM symbol using a pilot subcarrier. In addition, an error caused by phase correction using a pilot subcarrier can be eliminated by phase correction using a pilot symbol. Therefore, optimal phase correction can be performed for a multilevel modulation method having a large multilevel class.
By the way, in the above example, the predetermined value of the phase correction
For example, consider the case where the
In this case, the multi-level modulation
Here, in the case of the first phase correction scheme, the transmission efficiencies P1 of QPSK, 16 QAM, and 64 QAM are 0.97, 0.83, and 0.75 (see Table 2).
On the other hand, in the case of the second phase correction method, the transmission efficiency P2 is 0.92.
In this case, the phase correction
That is, the phase correction
In this case, the optimum phase correction can be performed according to the multi-level modulation method performed by the
(Second Embodiment)
The
The
Here, the
In addition, the
The
As shown in FIG. 7, the
The A /
The down
The
The phase correction method using the remodulation is performed by the phase
The phase correction method using the pilot symbol is performed by the phase
The multi-level modulation
The phase correction
Here, in the case of 16 QAM, the distance between symbols on the complex plane is short, so that the tolerance angle θ1 of each symbol point is smaller than that of QPSK. Therefore, when the multi-level modulation scheme is 16 QAM, if the same phase correction scheme as that of the QPSK is used, there is a possibility that a large number of errors are included in the bit sequence after the demodulation, and thus the complex symbol after the remodulation cannot be said to be accurate.
Therefore, the phase correction
The
As described above, the
As described above, according to the
Claims (5)
The modulated signal comprises a sequence of symbols representing data transmitted to the receiver,
The symbol has a corresponding relationship with a bit sequence determined by a multi-level modulation scheme selected by the transmitter,
The receiver includes a multi-level modulation method determination unit, a phase correction method selection unit, a phase correction unit, and a determination unit,
The multi-level modulation scheme determination unit is configured to determine, according to the modulation signal received from the transmitter, the multi-level modulation scheme used to generate the received modulation signal,
The phase correction method selection unit is a phase correction used to correct a phase of a symbol of the modulated signal based on a multi level grade of the multi level modulation method determined by the multi level modulation method determination unit. Configured to select a method from a plurality of predetermined phase correction methods,
The phase correction unit is configured to correct the phase of the symbol by using the phase correction method selected by the phase correction method selection unit,
The determination unit is configured to determine a bit sequence corresponding to the symbol whose phase has been corrected by the phase correction unit based on the multi-level modulation method determined by the modulation method determination unit,
The transmitter is configured to perform a primary modulation scheme and a secondary modulation scheme,
The primary modulation scheme is configured as a multilevel modulation scheme that generates a primary modulation symbol representing the symbol and is selected by a predetermined criterion from a plurality of multilevel modulation schemes having different multilevel grades,
The secondary modulation scheme generates a secondary modulation symbol by multiplexing a plurality of subcarriers having a complex amplitude based on the primary modulation symbol, and generates the modulation signal composed of the plurality of secondary modulation symbols. It is configured as a multicarrier modulation scheme,
The modulated signal has a pilot symbol for each predetermined regular interval,
The pilot symbol is configured as a predetermined secondary modulation symbol specific to the receiver,
The predetermined second modulation symbol is provided as a subcarrier having a predetermined complex amplitude specific to the receiver,
The secondary modulation symbol comprises a pilot subcarrier,
The pilot subcarrier is configured as a predetermined subcarrier specific to the receiver,
The predetermined subcarrier has a predetermined complex amplitude specific to the receiver,
The phase correction method selection unit is configured to correct the phase of the symbol by using the pilot symbols when the multi level class of the multi level modulation method determined by the multi level modulation method determination unit is less than a predetermined value. Select a first phase correction scheme and select a second phase correction scheme to correct the phase of the symbol using the pilot subcarrier if the multi-level class is greater than or equal to a predetermined value.
The phase correction method selection unit selects the report of the first phase correction method if the multi level class of the multi level modulation method determined by the multi level modulation method determination unit is less than a predetermined value, and the multi level And select both of the first phase correction method and the second phase correction method if the multi-level class of the multi-level modulation method determined by the modulation method determination unit is equal to or greater than a predetermined value.
The phase correction unit corrects the phase of the symbol according to the second phase correction method when both of the first phase correction method and the second phase correction method are selected by the phase correction method selection unit. And then correct the phase of the symbol in accordance with the first phase correction scheme.
And the predetermined value is selected based on a transmission efficiency when the phase correction unit corrects the phase of the symbol by using the phase correction method selected by the phase correction method selection unit.
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JP2008082122A JP5215704B2 (en) | 2008-03-26 | 2008-03-26 | Adaptive demodulation method |
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KR (1) | KR101209501B1 (en) |
CN (1) | CN101981842B (en) |
HK (1) | HK1154131A1 (en) |
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JPWO2010070884A1 (en) * | 2008-12-15 | 2012-05-24 | パナソニック株式会社 | Receiving apparatus and receiving method |
JP5669668B2 (en) * | 2011-05-18 | 2015-02-12 | 三菱電機株式会社 | Demodulator and communication device |
CN104272692B (en) * | 2012-04-24 | 2017-09-26 | 日本电气株式会社 | carrier reproducer and carrier reproducing method |
JP7167916B2 (en) * | 2017-07-06 | 2022-11-09 | ソニーグループ株式会社 | Communication device and communication method |
JP2021057787A (en) * | 2019-09-30 | 2021-04-08 | 沖電気工業株式会社 | Signal conversion device, modulation device, signal reverse conversion device, demodulation device, modulation method, demodulation method, and transmission device |
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JP2000269919A (en) * | 1999-03-16 | 2000-09-29 | Matsushita Electric Ind Co Ltd | Ofdm communication unit |
JP3844951B2 (en) * | 2000-09-21 | 2006-11-15 | 三菱電機株式会社 | Receiver and adaptive equalization processing method |
US6587697B2 (en) * | 2001-05-14 | 2003-07-01 | Interdigital Technology Corporation | Common control channel uplink power control for adaptive modulation and coding techniques |
JP2004364321A (en) * | 2001-06-01 | 2004-12-24 | Sony Corp | Inverse spread apparatus, propagation line estimate apparatus, receiver and interference suppressing apparatus, inverse spread, propagation line estimate, reception and interference suppressing method, program for them, and recording medium with the program recorded thereon |
EP1355467B8 (en) * | 2002-04-16 | 2005-12-07 | Sony Deutschland Gmbh | Orthogonal frequency division multiplexing (OFDM) system with channel transfer function prediction |
TWI229981B (en) * | 2003-10-06 | 2005-03-21 | Chunghwa Telecom Co Ltd | Receiver of multi-carrier communication system |
JP4359162B2 (en) * | 2004-02-24 | 2009-11-04 | 三洋電機株式会社 | Receiver |
JP4290048B2 (en) * | 2004-03-23 | 2009-07-01 | 三洋電機株式会社 | Receiving method and apparatus |
TWI268068B (en) * | 2004-11-10 | 2006-12-01 | Ind Tech Res Inst | Method and device for modulation recognition of digitally modulated signals with multi-level magnitudes |
WO2007029406A1 (en) * | 2005-09-07 | 2007-03-15 | Nec Corporation | Adaptive radio/modulation apparatus, receiver apparatus, wireless communication system and wireless communication method |
WO2007066672A1 (en) * | 2005-12-06 | 2007-06-14 | Rohm Co., Ltd. | Frequency modulator and fm transmission circuit using the same |
WO2008129811A1 (en) * | 2007-03-23 | 2008-10-30 | Panasonic Corporation | Radio transmission device and radio reception device |
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2009
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WO2009119736A1 (en) | 2009-10-01 |
KR20100126568A (en) | 2010-12-01 |
TW201014291A (en) | 2010-04-01 |
JP5215704B2 (en) | 2013-06-19 |
TWI385990B (en) | 2013-02-11 |
CN101981842B (en) | 2014-05-14 |
JP2009239545A (en) | 2009-10-15 |
CN101981842A (en) | 2011-02-23 |
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