JP2000261401A  Method and device for orthogonal modulation and recording medium  Google Patents
Method and device for orthogonal modulation and recording mediumInfo
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 JP2000261401A JP2000261401A JP11061676A JP6167699A JP2000261401A JP 2000261401 A JP2000261401 A JP 2000261401A JP 11061676 A JP11061676 A JP 11061676A JP 6167699 A JP6167699 A JP 6167699A JP 2000261401 A JP2000261401 A JP 2000261401A
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 acquiring
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 239000000562 conjugates Substances 0.000 claims abstract description 32
 241000212893 Chelon labrosus Species 0.000 claims description 5
 238000006243 chemical reactions Methods 0.000 description 14
 238000010586 diagrams Methods 0.000 description 3
 239000000969 carriers Substances 0.000 description 2
 230000000875 corresponding Effects 0.000 description 2
 281000137952 General Computer companies 0.000 description 1
 238000005070 sampling Methods 0.000 description 1
 230000001629 suppression Effects 0.000 description 1
 230000001131 transforming Effects 0.000 description 1
Abstract
−K and the inverse Fourier transformer 103. Each of the complex conjugate calculators 1021 to 102K generates a modulation symbol representing a conjugate complex number of a value represented by the modulation symbol supplied thereto, and supplies the modulation symbol to the inverse Fourier transformer 103. The inverse Fourier transformer 103 performs an inverse Fourier transform on a value represented by the modulation symbol supplied thereto, modulates a plurality of subcarriers with these modulation symbols, and generates a digital signal representing a quadrature modulated wave frequencymultiplexed. . The digital signal generated by the inverse Fourier transformer 103 is converted to serial by the parallelserial converter 104 and output from the output terminal 105.
Description
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a quadrature modulator and a quadrature modulation method for quadrature modulating a subcarriermultiplexed modulated signal, such as OFDM (Orthogonal Frequency Division Multiplexing).
[0002]
2. Description of the Related Art Conventionally, OFDM (orthogonal frequency division multiplexing,
Japanese Unexamined Patent Publication (Kokai) No. 746219 discloses a modulator that generates a modulated wave obtained by orthogonally modulating a main carrier with a modulated signal in which subcarriers are multiplexed, as in Orthogonal Frequency Division Multiplexing.
The operation of the configuration disclosed in Japanese Patent LaidOpen No. 746219 will be described with reference to FIG. As shown in FIG. 3, the modulator includes an input terminal 1000, a fast inverse Fourier transform (IFFT) circuit 1001, and a data conversion circuit 1
0011 and 10012 and digitalanalog conversion circuits (D / A conversion circuits) 10031 and 1003
2 and lowpass filters 10041 and 10042
A local oscillator 1007, a quadrature modulation circuit 1005,
An output terminal 1006.
[0004] The modulation symbol supplied to the input terminal 1000 is supplied to a fast inverse Fourier transformer 1001, which generates an orthogonal frequency multiplexed signal in baseband. The inphase component and the quadrature component of the orthogonal frequency multiplexed signal in the baseband are respectively converted into data conversion circuits 10011 and 10012.
Accordingly, the peak value for suppressing the nonlinear distortion of the amplifier is limited.
Further, the inphase component and the quadrature component output from the data conversion circuits 10011 and 10012 are converted into digitalanalog conversion circuits (D / A conversion circuits), respectively.
10031 and 10032) are converted into analog signals. Then, the inphase component and the quadrature component that have been converted into analog signals are converted to lowpass filters 10041 and 10041.
After removing unnecessary high frequency components by 42, the signal is supplied to the quadrature modulation circuit 1005. Quadrature modulation circuit 100
5 quadraturemodulates the main carrier generated by the local oscillator 1007 with the inphase and quadrature components supplied thereto,
Generate a modulated wave.
[0006]
However, in the case of the method disclosed in Japanese Patent LaidOpen No. 746219, since the quadrature modulation is performed using the analog signal obtained by the D / A conversion, the inphase component and the quadrature component of the modulation signal are used. It is necessary to adjust the balance and the like, and the configuration becomes complicated. In addition, there is a problem that a modulation error increases due to variations in electrical characteristics of components of a device that performs quadrature modulation using an analog signal and deterioration over time.
[0007] The present invention has been made in view of the above situation, and is based on OFDM (Orthogonal Frequency Division Multiplexing).
It is an object of the present invention to provide a quadrature modulation device and a quadrature modulation method for performing quadrature modulation on a modulation signal in which subcarriers are multiplexed with high accuracy, as in the case of ency division multiplexing.
[0008]
In order to achieve the above object, a quadrature modulation apparatus according to a first aspect of the present invention generates a quadrature modulated wave representing a signal obtained by frequencymultiplexing a plurality of quadraturemodulated subcarriers. A first digital signal representing the phase and amplitude of a signal for modulating the subcarrier in a complex number format, the digital signal acquiring means for acquiring the number of the subcarriers, and the digital signal acquiring means acquiring the first digital signal. Complex conjugate operation means for creating a second digital signal representing a conjugate complex number of the complex number represented by each of the first digital signals thus obtained; and acquiring each of the first digital signals from the digital signal acquiring means; Each of the second digital signals is obtained from the conjugate operation means, and each of the subcarriers and each of the first digital signals represented by the first digital signal are obtained. And inverse Fourier transform means for generating a third digital signal representative of the quadrature modulated waves obtained by superimposing a signal representing the value obtained by multiplying the number onetoone to each other,
It is characterized by having.
According to such a quadrature modulator, a modulated signal in which subcarriers are multiplexed is realized by digital processing without handling an analog signal. For this reason, according to such a quadrature modulation device, modulation of a quadrature modulation wave in which subcarriers are multiplexed is performed with high accuracy.
[0010] The inverse Fourier transform means is used to obtain the first and second digital signals on a onetoone basis.
It has N (where N is a predetermined natural number) ranked input terminals, and is obtained from each of the (N−K) th (where K is a predetermined natural number equal to or less than N) or Nth input terminal Represents the quadrature modulated wave obtained by superimposing a signal obtained by multiplying a complex number represented by the first digital signal on a onetoone basis on the K subcarriers whose frequencies are different at substantially constant intervals. A means for generating a third digital signal may be provided. In this case, the digital signal acquiring unit converts each of the first digital signals acquired by the digital signal acquiring unit into
Means for supplying (N−K) th to Nth input terminals of the inverse Fourier transform means on a onetoone basis, wherein the complex conjugate operation means outputs each of the second digital signals generated by itself It suffices if the first to Kth input terminals of the inverse Fourier transform means have a means for supplying onetoone.
[0011] Further, the inverse Fourier transform means includes a predetermined signal indicating that the first and second digital signals are not supplied from the input terminal to which the first and second digital signals are not supplied. It may have a means for acquiring a null signal.
In a quadrature modulation method according to a second aspect of the present invention, in the quadrature modulation method for generating a quadrature modulation wave representing a signal obtained by frequencymultiplexing a plurality of subcarriers subjected to quadrature modulation, the subcarrier is modulated. A first digital signal representing the phase and amplitude of the signal
A digital signal acquiring step for acquiring the number of subcarriers, and a complex conjugate operation step for creating a second digital signal representing a complex conjugate of a complex number represented by each of the first digital signals acquired in the digital signal acquiring step Acquiring each of the first digital signals acquired in the digital signal acquiring step, acquiring each of the second digital signals generated in the complex conjugate operation step, and acquiring each of the subcarriers and each of the subcarriers. An inverse Fourier transform step of generating a third digital signal representing the quadrature modulated wave obtained by superimposing signals representing values obtained by multiplying a complex number represented by the first digital signal on a onetoone basis. It is characterized by the following.
According to such a quadrature modulation method, a modulated signal in which subcarriers are multiplexed is realized by digital processing without handling an analog signal. Therefore, according to such a quadrature modulation method, modulation of a quadrature modulated wave in which subcarriers are multiplexed is performed with high accuracy.
A computerreadable recording medium according to a third aspect of the present invention is a computerreadable recording medium for transmitting a first digital signal representing a phase and an amplitude of a signal for orthogonally modulating a subcarrier in a complex number format. Digital signal acquisition means for acquiring the number of subcarriers, and complex conjugate operation means for producing a second digital signal representing a complex conjugate of a complex number represented by each of the first digital signals acquired by the digital signal acquisition means Acquiring each of the first digital signals from the digital signal acquiring means, acquiring each of the second digital signals from the complex conjugate calculating means, and acquiring each of the subcarriers and each of the first digital signals.
To function as inverse Fourier transform means for generating a third digital signal representing the quadrature modulated wave obtained by superimposing signals representing values obtained by multiplying the complex number represented by the digital signal by 1 to 1 on a onetoone basis. Is recorded.
According to the computer that executes the program recorded on such a recording medium, the modulated signal on which the subcarriers are multiplexed is realized by digital processing without handling an analog signal. Modulation of the orthogonal modulation wave is performed with high accuracy.
[0016]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a quadrature modulation apparatus and a quadrature modulation method according to embodiments of the present invention will be described using a digital quadrature modulator as an example.
FIG. 1 shows a physical configuration of a digital quadrature modulator according to an embodiment of the present invention. As shown, the digital quadrature modulator comprises an input terminal 100,
Serialparallel converter 101 and complex conjugate calculator 1021
And a fast inverse Fourier transformer 103, a parallelserial converter 104, and an output terminal 105.
The serialparallel converter 101 is composed of, for example, a shift register. Serialparallel converter 101
Obtains and stores the modulation symbols sequentially supplied to the input terminal 100.
The modulation symbol is digital data representing the value of a signal to be transmitted by a quadrature modulated wave generated by the digital quadrature modulator. The value represented by the modulation symbol is, for example, a case where the instantaneous value of the amplitude and phase of a modulated wave obtained by modulating a subcarrier to be described later by 16QAM (Quadrature Amplitude Modulation) is represented in a complex format. , Imaginary part and real part.
Each time the serialparallel converter 101 stores a predetermined number K of modulation symbols (where K is a natural number that is an odd number), the serialparallel converter 101 arranges the stored K modulation symbols in the order of acquisition and collectively arranges them. The modulation symbol stored therein is deleted from the storage.
K complex conjugate calculators 1021 to 1021
K are substantially the same as each other, and are ranked from the first to the Kth. The Jth complex conjugate operator 102J (where J is a natural number equal to or less than K) acquires and acquires the Jth modulation symbol from the top of the modulation symbols output collectively by the serialparallel converter 101. A modulation symbol indicating a value corresponding to a complex conjugate of the value indicated by the modulation symbol is generated, and the generated modulation symbol is output.
The highspeed inverse Fourier transformer 103 includes a DSP
(Digital Signal Processor) and the like, and has N input terminals (where N is an even natural number) and an output terminal. Each input of the fast inverse Fourier transformer 103 is
It is ranked from 1st to Nth. Below,
Xth input terminal (where X is a natural number not more than N) is P
[Y]. [However, Y = ｛(− N / 2) +
(X1)}. ]
The fast inverse Fourier transformer 103 converts the Jth modulation symbol output from the serialtoparallel converter 101 collectively from the beginning into an input terminal P [(N / 2) J].
Get more. Further, the complex conjugate calculator 102J is used as a modulation symbol indicating a value corresponding to the complex conjugate of the value indicated by the modulation symbol supplied to the input terminal P [(N / 2) J].
Is output to the input terminal P [− (N / 2) +
J].
The fast Fourier transformer 103 has an input terminal P [(N / 2) J] and an input terminal P [(N / 2) +
J], a predetermined null signal indicating that no modulation symbol is supplied is acquired from the input terminal except for the input terminal. Specifically, for example, the input terminal P [(N / 2) J] and the input terminal P
Input terminals except for [(N / 2) + J] are grounded, and the ground potential represents a null signal.
Then, the fast inverse Fourier transformer 103
(A1) Input terminal P [｛(− N / 2) + (NK−
X)｝] (where X is a natural number not less than 1 and not more than K), the frequency of which is [fc + {X (K + 1) / 2} among the orthogonal modulation waves to be generated.
.DELTA.f], and (b1) the input end P
The value indicated by the modulation symbol supplied to [{(−N / 2) + X}] (where X is a natural number not less than 1 and not more than K) has a frequency of [−fc + ｛, among the orthogonal modulation waves to be generated. X
− (K + 1) / 2｝ · Δf].
Performs an inverse Fourier transform. Where fc
Represents a predetermined center frequency, and Δf represents a frequency interval of a subcarrier described later.
The value obtained as a result of the inverse Fourier transform executed by the fast inverse Fourier transformer 103 has a frequency of [｛X−
(K + 1) / 2｝ · Δf] is quadraturemodulated so that the phase and amplitude indicated by the modulation symbol supplied to the input terminal P [{(− N / 2) + (NK + X)}] are obtained. Represents a time change of a signal obtained by superimposing K signals obtained by the above.
Then, the fast inverse Fourier transformer 103
As a result of the inverse Fourier transform, a plurality of digital signals representing values obtained by sampling the instantaneous values of the modulated wave at substantially equal intervals are arranged in time lapse order and output collectively from an output terminal.
The parallelserial converter 104 acquires digital signals output from the output terminal of the fast inverse Fourier transformer 103 all at once, and converts each acquired digital signal to the first one (the instantaneous value at the earliest time). ) Are sequentially output.
Next, this digital quadrature modulator is constituted by a 16point fast inverse Fourier transformer 103, and 16Q
An example in which a modulated wave representing a frequency multiplex of five subcarriers modulated by the AM method is generated (that is, the value of N is 16 and the value of K is 5 in the above description) is an example. Next, a description will be given with reference to FIG.
The modulation symbols 2001, 2002, 2
When 003, 2004 and 2005 are sequentially supplied to the serialparallel converter 101, the serialparallel converter 10
1 sequentially stores these converted symbols.
In the following, in order to facilitate understanding,
Modulation symbols 2001 to 2005 are 16 complex values (FIG. 1) that a modulation symbol of 16QAM modulation can take.
Represents one of the values (represented as “●” and “の う ち”) (represented as “●” in FIG. 1).
That is, as shown in the figure, the value of the real part (Iaxis component) of the complex value that can be taken by the modulation symbol of 16QAM modulation is 3d, d, d and 3d (where d is a predetermined positive value). Real number) and the value of the imaginary part (Q axis component) is 3j
Assuming that d, −jd, jd, and 3jd (where j is an imaginary unit), modulation symbols 2001 to 2005 are
In order, (−d−jd), (d−jd), (−3d−3j)
d), (−3d + 3jd) and (d + jd).
When the modulation symbol 2005 is stored, the modulation symbols 2001 to 200 stored therein are stored.
−5 to the complex conjugate calculators 1021 to 1025 to obtain 1
Supply one to one. Further, these modulation symbols are supplied onetoone to the input terminals P [7] to P [3] of the fast inverse Fourier transformer 103.
The modulation symbols 2001 to 200
5 supplied with the complex conjugate calculators 1021 to 1025
Creates a modulation symbol that represents a conjugate complex number of a complex number represented by the modulation symbol supplied to each of them, and converts the created modulation symbol to an input terminal P [− of the fast inverse Fourier transformer 103.
7] to P [3] on a onetoone basis.
The fast inverse Fourier transformer 103 has an input terminal P
Null signals are obtained from [−8], P [−2] to P [2], and P [8]. Then, the fast inverse Fourier transformer 10
3 are (a2) input terminals P [3], P [4], P
The values indicated by the modulation symbols supplied to [5], P [6], and P [7] indicate that the frequency of the orthogonal modulation wave to be generated is {fc− (2 · Δf)}, ｛ fcΔ
f｝, fc, (fc + Δf) and ｛fc + (2 · Δ
f) represents the intensity of the component｝, and (b2) the input end P
[7], P [6], P [5], P [4] and P
The value indicated by the modulation symbol supplied to [3] is, in the quadrature modulated wave to be generated, the frequency in order of ｛fc
− (2 · Δf)｝, ｛−fc−Δf｝, (−fc),
An inverse Fourier transform is performed to represent the intensity of the component that is (−fc + Δf) and {−fc + (2 · Δf)}.
Then, the fast inverse Fourier transformer 103
Digital signals representing the result of the inverse Fourier transform are
They are arranged in the order of elapse of time and supplied collectively from the output terminal to the parallelserial converter 104, and the parallelserial converter 104 sequentially outputs the supplied digital signals from the first one. The digital signal output from the parallelserial converter is
In the range of ± (2 · Δf) around the frequency fc, the frequency Δ
It represents the time change of a modulated wave obtained by frequency multiplexing 16 QAMmodulated five subcarriers arranged at f intervals.
As described above, the fast inverse Fourier transformer 10
When the modulation symbol is supplied to 3, the inverse fast Fourier transformer 103 performs an inverse fast Fourier transform on the complex number represented by the modulation symbol, and outputs the result to the parallelserial conversion circuit 104. The parallelserial conversion circuit 104 rearranges the output of the fast inverse Fourier transformer 103 in series so as to have a continuous waveform on the time axis, and outputs the rearranged output via the output terminal 105. Then, the fast inverse Fourier transformer 103 is realized by a digital circuit. For this reason, this digital quadrature modulator generates a quadrature modulated wave without handling an analog signal.
The configuration of the digital quadrature modulator is not limited to the above. For example, the number of subcarriers (ie, the value of K described above) does not need to be odd, but may be even. However, in this case, the subcarrier and the frequency whose frequency matches the center frequency fc are (−
There will be no subcarrier that matches fc).
The input terminal P [｛(− N / 2) + (N−
K + X)}] (where X is a natural number not less than 1 and not more than K) and the values indicated by the modulation symbols supplied to the input terminal P [{(− N / 2) + X}] are not necessarily (a1) and (b2). It is not necessary to satisfy the abovedescribed condition. For example, (a
3) Input terminal P [{(N / 2) + (NK + X)}]
(Where X is a natural number not less than 1 and not more than K), the value indicated by the modulation symbol is such that the frequency of the subcarrier in the orthogonal modulation wave to be generated is (fx−W) or more (fx + W).
W) represents the intensity of components of different frequencies (where fx and W are predetermined positive values), and (b3)
The value indicated by the modulation symbol supplied to the input terminal P [{(− N / 2) + (NK−X)}] indicates the intensity of the component of the orthogonal modulation wave to be generated whose frequency is F. , The value indicated by the modulation symbol supplied to the input terminal P [{(− N / 2) + X}] is the component of the quadrature modulated wave to be generated whose subcarrier frequency is (−F). The inverse Fourier transform may be executed as a value representing the intensity of.
Further, the input terminal P [｛(− N / 2) + (N
−K + X)}] and input terminal P [{(− N / 2) + X}]
May include a null signal.
Although the embodiment of the present invention has been described above, the quadrature modulation device of the present invention can be realized by using a general computer system without using a dedicated system. For example, a quadrature modulation device that executes the abovedescribed processing can be configured by installing the program for executing the abovedescribed operation from a medium (a floppy disk, a CDROM, or the like) storing the program in a personal computer. it can.
The medium for supplying the program to the computer may be a communication medium (a medium that temporarily and fluidly stores the program, such as a communication line, a communication network, or a communication system). For example, the program may be posted on a bulletin board (BBS) of a communication network and distributed via the network. Then, by starting this program and executing it in the same manner as other application programs under the control of the OS, the abovedescribed processing can be executed.
When the OS shares part of the processing,
Alternatively, when the OS constitutes a part of one component of the present invention, a program excluding the part may be stored in the recording medium. Also in this case, in the present invention, it is assumed that the recording medium stores a program for executing each function or step executed by the computer.
[0044]
As described above, according to the present invention, OFDM (Orthogonal Frequency Division Multiplexing)
A quadrature modulation device and a quadrature modulation method for performing quadrature modulation on a modulated signal in which subcarriers are multiplexed with high precision, such as ency division multiplexing, are realized.
FIG. 1 is a system diagram showing a configuration of a digital quadrature modulator according to an embodiment of the present invention.
FIG. 2 is a diagram for explaining the operation of the digital quadrature modulator of FIG.
FIG. 3 is a system diagram showing a conventional quadrature modulator.
100, 1000 input terminal 101 serialparallel conversion circuit 1021 to 102K complex conjugate operation circuit 103 highspeed inverse Fourier transform circuit 104 parallelserial conversion circuit 105, 1006 output terminal 2001 to 2005 modulation symbol 1001 highspeed Inverse Fourier transformation circuit 10011, 10012 Data conversion circuit 10031, 10032 Digitalanalog conversion circuit 10041, 10042 Lowpass filter 1005 Quadrature modulation circuit 1007 Local oscillator
Claims (5)
Represents a complex conjugate of a complex number represented by the digital signal of
Complex conjugate operation means for creating a digital signal of the following; and obtaining each of the first digital signals from the digital signal obtaining means; and obtaining each of the second digital signals from the complex conjugate operation means.
A third signal representing the quadrature modulated wave obtained by superimposing signals representing values obtained by multiplying each of the subcarriers and the complex number represented by each of the first digital signals on a onetoone basis. And an inverse Fourier transform unit for generating a digital signal of the following.
It has N (where N is a predetermined natural number) ranked input terminals, and is obtained from each of the (N−K) th (where K is a predetermined natural number equal to or less than N) or Nth input terminal Represents the quadrature modulated wave obtained by superimposing a signal obtained by multiplying a complex number represented by the first digital signal on a onetoone basis on the K subcarriers whose frequencies are different at substantially constant intervals. Means for generating a third digital signal, wherein the digital signal acquiring means converts each of the first digital signals acquired by the digital signal acquiring means into (NK) th to Nth input signals of the inverse Fourier transform means. Means for supplying onetoone at one end, wherein the complex conjugate operation means applies the second digital signal generated by itself to the first to Kth input terminals of the inverse Fourier transform means in onetoone correspondence. Means to supply to 1 Comprising, quadrature modulation apparatus according to claim 1, characterized in that.
Represents a complex conjugate of a complex number represented by the digital signal of
Complex conjugate operation means for creating a digital signal of the following; and obtaining each of the first digital signals from the digital signal obtaining means; and obtaining each of the second digital signals from the complex conjugate operation means.
A third signal representing the quadrature modulated wave obtained by superimposing signals representing values obtained by multiplying each of the subcarriers and the complex number represented by each of the first digital signals on a onetoone basis. Inverse Fourier transform means for generating a digital signal, and a computerreadable recording medium on which a program for causing the digital signal to function is recorded.
Priority Applications (1)
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JP11061676A JP2000261401A (en)  19990309  19990309  Method and device for orthogonal modulation and recording medium 
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JP11061676A JP2000261401A (en)  19990309  19990309  Method and device for orthogonal modulation and recording medium 
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Cited By (3)
Publication number  Priority date  Publication date  Assignee  Title 

JP2007174679A (en) *  20051223  20070705  Samsung Electronics Co Ltd  Method of frequency hopping of ofdm symbol 
WO2008018145A1 (en) *  20060810  20080214  Panasonic Corporation  Ofdm transmitter apparatus and ofdm receiver apparatus 
JP2008514154A (en) *  20040922  20080501  サムスン エレクトロニクス カンパニー リミテッド  OFDM transceiver, OFDM signal processing method using the same, recording medium, and OFDM receiver signal demodulation method 

1999
 19990309 JP JP11061676A patent/JP2000261401A/en active Pending
Cited By (4)
Publication number  Priority date  Publication date  Assignee  Title 

JP2008514154A (en) *  20040922  20080501  サムスン エレクトロニクス カンパニー リミテッド  OFDM transceiver, OFDM signal processing method using the same, recording medium, and OFDM receiver signal demodulation method 
JP2007174679A (en) *  20051223  20070705  Samsung Electronics Co Ltd  Method of frequency hopping of ofdm symbol 
WO2008018145A1 (en) *  20060810  20080214  Panasonic Corporation  Ofdm transmitter apparatus and ofdm receiver apparatus 
JPWO2008018145A1 (en) *  20060810  20091224  パナソニック株式会社  OFDM transmitter and OFDM receiver 
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