Source: https://patents.google.com/patent/EP1601149A2/en
Timestamp: 2019-09-20 13:02:54
Document Index: 538170421

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EP1601149A2 - Transmitter and transmission control method - Google Patents
Transmitter and transmission control method Download PDF
EP1601149A2
EP1601149A2 EP05253100A EP05253100A EP1601149A2 EP 1601149 A2 EP1601149 A2 EP 1601149A2 EP 05253100 A EP05253100 A EP 05253100A EP 05253100 A EP05253100 A EP 05253100A EP 1601149 A2 EP1601149 A2 EP 1601149A2
EP05253100A
EP1601149B1 (en
EP1601149A3 (en
Takahiro c/o Intellectual Property Departmen Asai
Hiromasa c/o Intellectual Property Departm Fujii
Jiyun c/o Intellectual Property D. NTT DoCoM Shen
Hirohito c/o Intellectual Property D. NTT Do Suda
2004-05-25 Priority to JP2004155032 priority Critical
2004-05-25 Priority to JP2004155032A priority patent/JP4398791B2/en
2005-05-19 Application filed by NTT Docomo Inc filed Critical NTT Docomo Inc
2005-11-30 Publication of EP1601149A2 publication Critical patent/EP1601149A2/en
2011-03-30 Publication of EP1601149A3 publication Critical patent/EP1601149A3/en
2013-06-26 Publication of EP1601149B1 publication Critical patent/EP1601149B1/en
As a method of reducing the PAPR, clipping (+ filtering) (for example, see the non-patent document #1, listed below); a PTS method (for example, see the non-patent document #2); and a cyclic shifting method (for example, see the non-patent document #3) have been proposed:
Non-patent document #1: X. Li and L. J. Cimini, "Effects of clipping and filtering on the performance of OFDM", IEEE Commun. Lett., vol. 2, no. 5, pp. 131-133, May 1998;
Non-patent document #2: L. J and N. R. Sollenberger, "Peak-to-Average power ratio reduction of an OFDM signal using partial transmit sequence", IEEE Commun. Lett., vol. 4, no. 3, pp. 86-88, March 2000;
Non-patent document #3: G. R. Hill, M. Faulkner and J. Singh, "Reducing the peak-to-average power ratio in OFDM by cyclically shifting partial transmit sequence", Electronics Letters, vol. 36, No. 6, pp. 560-561, March 2000; and
Non-patent document #4: Miyashita, Nishimura et al., "Eigenbeam-Space Division Multiplexing (E-SDM) in a MIMO Channel", The Institute of Electronics, Information and Communication Engineers, Technical Report of IEICE, RCS2002-53 (2002-05).
A configuration of the low peak IFFT part 8 is described now with reference to FIG. 3.
In this method, the separated IFFT part 8-1 divides a plurality of input subcarriers into a plurality of groups, for example, NG groups (NG is an integer and NG > 1), and carries out IFFT thereon. The configuration of the separated IFFT part 8-1 is illustrated with reference to FIG. 4 for example in which 8 points of IFFT are divided into two groups.
In this system applying the PAPR reduction according to the cyclic shifting method or the PTS method, the peak reducing parts 8-21 and 8-22 carry out cyclic shifting or phase rotation on the input signals [F(0) F(1) ... F(NFFT-1)]. After that, the thus-obtained signal components are added by the adding part 8-24. The peak reduction control part 8-23 controls the cyclic shifting amount or the phase rotation amount in such a manner as to reduce the peak appearing in the output signals. Thereby, generation of a large peak is suppressed.
That is, in a case where the clipping (+ filtering) is applied to reduce the PAPR, orthogonality among the subcarriers may not be kept, inter-subcarrier interference may occur, and thus, transmission performance may degrade.
For this purpose, according to the present invention, a transmitter includes: a peak reducing part carrying out peak reduction processing; an OFDM signal generating part generating an OFDM signal from input information signal; a cyclic shifting part generating a signal obtained from cyclically shifting the OFDM signal; and an adding part adding the OFDM signal and the cyclically shifted signal together. In this configuration, peak suppression can be carried out
Further, a shift amount determining part determining a shift amount based on at least one of the OFDM signal and an output signal of the adding part may be provided, wherein: the cyclic shifting part may generate the signal cyclically shifted from the OFDM signal based on the shift amount determined by the shift amount determining part. In this configuration, the shift amount can be controlled, and thus, it is possible to achieve PARR reduction more effectively.
It is ideal to determine the weights such that: |s1'| = |s2'|, where: s1' = w1 × s(tp) + w2 × s (mod (tp - t' + NFFT, NFFT)) s2' = w2 × s(mod(tp + t', NFFT)) + w1 × s(tp), where w1, w2 denote the weights,
NFFT (NFFT is an integer and NFFT > 0) denotes an FFT point.
The amplitudes of s(tp+t') and s(tp-t') are compared, and the phase of the symbol having a smaller amplitude may become opposite from a phase of s(tp),
(iii)  denotes the phase rotation angle; and
s(tp) denotes a symbol causing a peak of the OFDM signal, 1 = π - [arg(s(mod(tp - t + NFFT, NFFT))) - arg(s(tp))]; 2 = π - [arg(s (mod(tp + t, NFFT)) - arg(s(tp))]; and  = {|s(mod(tp+t, NFFT))| × 1 + |s(mod (tp-t+NFFT, NFFT))| × 2}/{|s(mod(tp-t+NFFT, NFFT)| + |s(mod (tp+t, NFFT))|}, where mod denotes a remainder operator; and
Further, the shift amount determining part may determine the shift amount so that a value calculated by the following formula may be equal to or more than a fixed value: Re{s(tp+t') × s(tp-t')/s(tp)2} where:
and t' denotes the shift amount; and
Further, the shift amount determining part may determine a maximum shift amount in such a manner that the following requirements may be met, when a scattered pilot signal is applied: ((the number of FFT points)/(pilot signal inserting interval)) ≥ (maximum shift amount) + (impulse response length), based on an input impulse and a pilot signal, where the pilot signal inserting interval is an interval in a frequency direction. In this configuration, it is possible to control the shift amount within a fixed amount, and it is possible to satisfactorily estimate transmission characteristics also for a subcarrier for which the scattered pilot signal is not inserted by means of interpolation in the frequency direction.
The transmitter 100 in the first embodiment includes a symbol generating part 101 to which information bits are input; a S/P (serial/parallel) converting part 102 connected with the symbol generating part 101; an IFFT (inverse fast Fourier transform) part 103 connected to the S/P converting part 102; a P/S (parallel/serial) converting part 104 connected to the IFFT part 103; a peak reducing part 105 connected to the P/S converting part 104; and a GI adding part 106 connected to the peak reducing part 105. The peak reducing part 105 includes cyclic shifting parts 105-11 through 105-1k (k is an integer and k > 0) and an adding part 105-2 connected to the P/S converting part 104. The cyclic shifting parts 105-11 through 105-1k are connected to the adding part 105-2, which is connected to the GI adding part 106.
The symbol generating part 101 carries out, on the input information bit series, error correction coding, interleaving, symbol mapping and so forth so as to generate transmission symbols, which are then input to the S/P converting part 102. The S/P converting part 102 converts the input transmission symbols in a serial form into a parallel form, and inputs the thus-obtained signal into the IFFT part 103. The IFFT part 103 transforms the input signal into an orthogonal multi-carrier signal, and inputs the thus-obtained signal to the P/S converting part 104. The P/S converting part 104 converts the thus-input signal in the parallel form into a serial form, and inputs the thus-obtained signal into the peak reducing part 105. Processing in the peak reducing part 105 is described next. Each of the cyclic shifting parts 105-11 through 105-1k generates a signal shifted by a shift amount different from each other, and inputs the thus-obtained signal to the adding part 105-2.
The adding part 105-2 adds the signal from the P/S converting part 104 with the signals from the respective cyclic shifting parts 105-11 through 105-1k, together, and inputs the thus-obtained signal to the GI adding part 106. The GI adding part inserts a guard interval which includes a copy of a part of the given signal. The thus-obtained signal is then transmitted via the antenna.
In this case, the shift amounts of the respective cyclic shifting parts 105-11 through 105-1k should be determined. These shift amounts may be fixed. For example, the shift amount of i-th cyclic shifting part can be i points.
First, a symbol having the maximum amplitude in the transmission signal s(t)is referred to as smax. Further, a symbol max(|s'(t)|) having the maximum amplitude in the transmission signal s'(t) obtained after the peak suppression processing is carried out, is referred to as s'max.
When s'max = 0.5 × (s(t1) + s(t2)), and s(t1) = smax, then s'max = 0.5 × (smax + s(t2)).
If |smax| < |s'max|, the following formulas hold: |smax| < |0.5 × (smax + s(t2))|, |smax| < |s(t2)|.
This result contradicts |smax| > |s(t2)|.
Further, when s(t1) ≠ smax, and assuming that |s(t1)| ≥ |s(t2)| and |smax| < |s'max|, the following formulas hold:
|smax| < |s'max| = |0.5 × (s(t1) + s(t2))|,
|smaxI < |0.5 × (s(t1) + s(t2))|,
|smax| < |s(t1)|.
This result contradicts |smax| > |s(t1)|.
Accordingly, |smax| > |s'max| should hold.
The peak reducing part 109 according to the third embodiment includes cyclic shifting parts 109-11 through 109-1k, a shift amount and coefficient determining part 109-2 and a multiplier 109-4 connected to the P/S converting part 104, multipliers 109-51 through 109-5k connected to the cyclic shifting parts 109-11 through 109-1k respectively, and an adding part 109-3 connected to the multipliers 109-11 through 109-1k. The shift amount and coefficient determining part 109-2 is connected to the cyclic shifting parts 109-11 through 109-1k and the multipliers 109-51 through 109-1k, and the adding part 109-3 is connected to the GI adding part 106.
In the embodiment described above, only the shift amount is controlled. According to the third embodiment, the multipliers 109-4, 109-51 through 109-5k multiply the signals obtained from the cyclic shifting and output signals of the P/S converting part 104 with complex coefficients such as to further reduce the peak power. Thereby, it is possible to effectively reduce the peak power.
Here, a case is assumed that the single cyclic shifting part is applied, and the symbol acting as the peak in the OFDM signal before the peak reduction is referred to as s(tp). For a case where a cyclic shift amount in the cyclic shifting part is t' and coefficients for the multipliers 109-4 and 109-51 are w1 and w2, outputs of the adding part for s(tp) become following two signals: s'1 = w1 × s (tp) + w2 × s(mod(tp-t'+NFFT, NFFT)); and s'2 = w2 × s(mod(tp+t', NFFT)) + w1 × s(tp).
Therefrom, it is seen that s(tp) contributes to the two symbols. Accordingly, it is seen that, upon applying only s(tp), max(s'1, s'2) should be minimized.
When the shift amount t' is determined, the weights are determined in such a manner that a phase of one of the symbols of s(tp+t') and s(tp-t') having the smaller amplitude may be opposite to a phase of s(tp), and the amplitudes of the weights are adjusted to make |s'1| and |s'2| closer.
A method of determining the phase rotation angle is described. The shift amount and coefficient determining part 109-2 obtains the phase rotation amount by carrying out the following calculation, where  denotes the phase ration amount to obtain: 1 = π - [arg(s(mod(tp - t + NFFT, NFFT))) - arg(s(tp))]; 2 = π - [arg(s(mod(tp + t, NFFT))) - arg(s(tp))]; and  = {|s(mod(tp+t, NFFT))|× 1 + |s(mod (tp-t+NFFT, NFFT)| × 2}/{|s(mod(tp-t+NFFT, NFFT))| + |s(mod (tp+t, NFFT))|}.
As to the shift amount t', search may be carried out for all the shift amounts. However, a predetermined scope may be determined to be searched for detecting the shift amount.
In the above-mentioned scheme, calculation of the weights are carried out for each shift amount, and the shift amount and the weights which result in peak reduction are selected. However, it is also possible to estimate the shift amount which achieves a large peak reduction without calculating the weights. For example, the shift amount such that Re{s(tp+t') × s(tp-t') /s(tp)2} may be maximum or more than a fixed value may be searched for, and then, the weights are calculated for the thus-obtained shift amount.
The peak reducing part 110 according to the fourth embodiment includes cyclic shifting parts 110-11 through 110-1k, a multiplier 110-4 and shift amount and coefficient determining part 110-2 connected to the P/S converting part 104, multipliers 110-51 through 110-5k connected to the cyclic shifting parts 110-11 through 110-1k respectively, and an adding part 110-3 connected to the multipliers 110-11 through 110-1k. The shift amount and coefficient determining part 110-2 is connected to the cyclic shifting parts 110-11 through 110-1k the multipliers 110-1 and 110-51 through 110-5k. Further, the output signal of the adding part 110-3 is input to the shift amount and coefficient determining part 110-2. Further, the adding part 110-3 is connected to the GI adding part 106.
First, the shift amount and coefficient determining part 110-2 produces the peak suppressed signal only with the use of the output signal of the first cyclic shifting part 110-11.
Next, the shift amount and the complex coefficient of the first cyclic shifting part 110-11 are fixed, while, the transmission signal and the output signal of the first cyclic shifting part 110-11 are added together, then, the shift amount and the complex coefficient of the second cyclic shifting part 110-12 are determined in such a manner as to suppress the peak of thus-obtained signal.
At this time, the shift amount and the complex coefficient of the second cyclic shifting part 110-12 may be determined in such a manner that the peak in the signal obtained from combination of the outputs of the cyclic sifting parts 110-4, 110-51 and 110-52 may become smaller. The same processing is carried out repetitively through the k-th cyclic shifting part 110-1k.
Thereby, it is possible to determine the shift amounts and the complex coefficients efficiently without taking into account all the shift amounts of all the cyclic shifting parts 110-11 through 110-1k and the weights applied by the multipliers 110-51 through 110-5k.
Further, in the above-described scheme of determining the complex coefficients sequentially, the average transmission power of all the transmission signals obtained after the peak reduction changes according to the given weights. This problem may be solved by providing a processing part which normalizes the average transmission power of the peak reduced signal.
In the transmitter 100 according to the sixth embodiment, a plurality of peak reducing parts are provided, some of the peak reducing parts are disposed in parallel, and then, the outputs the peak reducing parts are connected as the input of another peak reducing part.
In a case where a scattered pilot signal is applied, the maximum shift amount should satisfy the following requirements: (the number of FFT points) / (pilot signal inserting interval (frequency direction)) ≤ (impulse response length) + (maximum shift amount).
The transmitter 300 of the tenth embodiment includes: an S/P converting part 301 to which data symbols are input; S/P converting parts 3021 through 302i; pilot inserting parts 3111 through 3111 connected to the S/P converting parts 3021 through 302i; ESDM signal generating parts 3031 through 3031 connected to the respective pilot inserting parts 3111 through 3111 respectively; low peak OFDM modulating parts 3041 through 304n connected to the ESDM signal generating parts 3031 through 3031;, pilot inserting parts 3051 through 305n connected to the respective low peak OFDM modulating parts 3041 through 304n; antennas 306 (#1 through #n) connected to the pilot inserting parts 3051 through 305n respectively; a coefficient generating part 307 connected to each of the low peak OFDM modulating parts 3041 through 304n; a feedback part 308 to which a feedback signal is input; a separating part 309 connected to the feedback part 308; and transmission weight generating parts 3101 through 3101 connected respectively to the coefficient generating part 307, the separating part 309 and the respective ESDM signal generating parts 3031 through 3031. In the transmitter 300 of FIG. 16, the low peak OFDM modulating parts 3041 through 304n include the above-described IFFT parts , peak reducing parts, P/S converting parts and GI adding parts.
First, in the coefficient generating part 307, the several shift amounts and complex coefficients are previously determined. In the convolution series generation, the shift amounts and the complex coefficients are determined in a random manner. As a relation among the convolution coefficient and the shift amount/weight, the convolution series is [ 1 w1 w2 ... wX ], where wX denotes the weight coefficient for a case of applying x-point cyclic shifting. There, x corresponds to the maximum sift amount. The convolution coefficient may be applied for all the transmission antennas in common, or, the different convolution coefficients may be applied for the respective transmission antennas.
The feedback signal input to the feedback part 308 is input to the separating part 309. The separating part 309 separates the feedback signal, and inputs the thus-separated signals to the transmission weight generating parts 3101 through 3101.
Each of the transmission weight generating parts 3101 through 3101 obtains a transfer function for the receiver from the input of the peak reducing part, that is, the coefficient generating part 307 generates signals of frequency domain corresponding to the generated coefficients, and outputs the same to the transmission weight generating parts 3101 through 3101, which multiply the thus-obtained signals with channel values of frequency domain between the transmission and reception antennas. The thus-obtained transfer function is used as the channel, to calculate the ESDM weight.
The ESDM signal generating parts 3031 through 3031 generate the ESDM signals based on signals obtained as a result of: the input symbols being S/P converted by means of the S/P converting part 301, the thus-obtained respective symbols being further S/P converted by means of the S/P converting parts 3021 through 302i, and then, the pilot signals being inserted thereto by means of the pilot inserting parts 3111 through 3111, as well as the ESDM weights.
The low peak OFDM modulating parts 3041 through 304n carry out OFDM modulation on the ESDM signals in which the pilot signals are inserted. In this case, each of the low peak OFDM modulating parts 3041 through 304n carries out the same processing as the above-described IFFT part, peak reducing part, P/S converting part and GI part.
The OFDM signals have pilot signals inserted thereto by means of the pilot signal inserting parts 3051 through 305n, and are transmitted. The pilot signals inserted there undergo neither the multiplication with the ESDM weights nor the peak reducing processing, and therefore, signals having low peaks should be previously selected as the pilot signals.
The pilot signals inserted in the pilot signal inserting parts 3051 through 305n have not undergone the peak reduction processing as well as multiplying with the ESDM weights, and thus, the values estimated from these pilot signals are the pure channel estimation values. These values are fed back to the transmitter, and are applied to generate the transmission weights. However, these channel estimation values are not those reflecting the peak reduction processing carried out in the transmitter. Therefore, it is not possible to directly detect the signals with the use of these channel estimation values.
On the other hand, the pilot signals inserted in the pilot inserting parts 3111 through 3111 have undergone the peak reduction processing, and thus, the channel estimation values detected from these pilot signals can be applied as the channel estimation values to detect the received signals.
First, a configuration of the transmitter not including the above-described peak suppression operation in the peak reducing part is applied thereto is described with reference to FIG. 17. This transmitter includes a S/P converting part 12 in which information bits are input; adders 240 through 241-1 connected to the S/P converting part 12; an inverse Fourier transform (IFFT) part 13 connected to the adders 240 through 241-1; a P/S converting part 14 connected to the inverse Fourier transform part 13; a GI inserting part 15 connected to the P/S converting part 14; an allowable peak level setting part 21 for setting an allowable peak level Cth; a peak component detecting part 22 connected to the allowable peak level setting part 21 and the S/P converting part 24 for detecting a peak component exceeding the allowable peak level Cth from the output of the S/P converting part 24; a Fourier transform part 23 connected to the peak component detecting part 22 for carrying out Fourier transform (which means FFT in this case) on the peak component; and a filter part 25 connected to the Fourier transform part 23. The adders 240 through 241-1 subtract the outputs of the filter part 25 from the input signals of the inverse Fourier transform part 13.
The peak component detecting part 22 has the allowable peak level Cth given by the allowable peak level setting part 21, subtracts the allowable peak level Cth from the level of.each time-domain signal component output from the S/P converting part 24, and thus, generates the peak components. However, when the level of the time-domain signal component is equal to or lower than the allowable peak level, the peak component detecting part 22 sets the peak component as being 0. In the transmitter configured as described above, the peak power reduction can be achieved.
The transmitter 400 includes, a symbol generating part 101 to which information bits are input; a S/P (serial/parallel) converting part 102 connected with the symbol generating part 101; an IFFT (inverse fast Fourier transform) part 103 connected to the S/P converting part 102; subtracters 1270 through 1271-1 connected to the IFFT part 103; a P/S (parallel/serial) converting part 104 connected to the subtracters 1270 through 1271-1; a peak reducing part 123 connected to the P/S converting part 104; and a GI adding part 106 and a P/S converting part 124 connected to the peak reducing part 123; an allowable peak level setting part 121 for setting an allowable peak level Cth; a peak component detecting part 122 connected to the allowable peak level setting part 121 and detecting a peak component exceeding the allowable peak level Cth from the output of the S/P converting part 124; a Fourier transform part 123 connected to the peak component detecting part 122 for carrying out Fourier transform (which means FFT in this case) on the peak component; and a filter part 125 connected to the Fourier transform part 123. The output signal of the filter part 126 is input to the subtracters 1270 through 1271-1. The subtracters 1270 through 1271-1 subtract the outputs of the filter part 126 from the signals input to the P/S converting part 104.
The symbol generating part 101 carries out, on the input information bit series, error correction coding, interleaving, symbol mapping and so forth so as to generate transmission symbols, which are then input to the S/P converting part 102. The S/P converting part 102 converts the input transmission symbols in a serial form into a parallel form, and inputs the thus-obtained signal into the IFFT part 103. The IFFT part 103 transforms the input signal into an orthogonal multi-carrier signal, and inputs the thus-obtained signal to the subtracters 1270 through 1271-1.
The peak component detecting part 122 has the allowable peak level Cth given by the allowable peak level setting part 121, subtracts the allowable peak level Cth from the level of each time-domain signal component output from the S/P converting part 124, and thus, generates the peak components. However, when the level of the time-domain signal component is equal to or lower than the allowable peak level, the peak component detecting part 122 sets the peak component as being 0. The peak component thus generated by the peak component detecting part 122 undergoes FFT processing and filtering, and then, is input to the subractor 1270 through 1271-1.
The subractor 1270 through 1271-1 subtract the peak components from the output signals of the IFFT part 103, and input the thus-obtained signals to the P/S converting part 104. The P/S converting part 104 converts the thus-input signal in the parallel form into a serial form, and inputs the thus-obtained signal into the peak reducing part 123. Processing in the peak reducing part 123 carries out peak reduction processing the same as that in the above-described embodiment. For example, as described above with reference to FIG. 5, each of the cyclic shifting parts 105-11 through 105-1n generates a signal shifted by a shift amount different from each other, and inputs the thus-obtained signal to the adding part 105-2. The adding part 105-2 adds the signal from the P/S converting part 104 with the signals from the respective cyclic shifting parts 105-11 through 105-1n, together, and inputs the thus-obtained signal to the GI adding part 106 and the S/P converting part 124. The GI adding part inserts a guard interval which includes a copy of a part of the given signal. The thus-obtained signal having the guard interval inserted thereto is then transmitted via the antenna. On the other hand, the S/P converting part 124 converts the given signal in a serial form into a parallel form, and input the thus-obtained signal to the peak component detecting part 122.
a cyclic shifting part generating a signal obtained cyclically shifted from the OFDM signal; and
The transmitter as claimed in claim 1, further comprising:
a shift amount determining part determining a shift amount based on at least one of the OFDM signal and an output signal of said adding part, wherein:
said cyclic shifting part generates the signal cyclically shifted from the OFDM signal based on the shift amount determined by said shift amount determining part.
The transmitter as claimed in claim 2, further comprising:
a multiplying part multiplying the OFDM signal and the cyclically shifted signal with the weights generated by said weight generating part, wherein:
said adding part adds the output signals of said multiplying part together.
The transmitter as claimed in claim 3, wherein:
phases of s(tp+t') and s(tp-t') may be opposite from a phase of s (tp),
where s(tp) denotes a symbol causing the peak of the OFDM signal; |s1'| = |s2'|, where: s1' = w1 × s (tp) + w2 × s(mod(tp - t' + NFFT, NFFT)) s2' = w2 × s(mod(tp + t', NFFT)) + w1 × s(tp), where w1, w2 denote the weights,
The transmitter as claimed in claim 4, wherein:
amplitudes of s(tp+t') and s(tp-t') are compared, and, the smaller one may be in opposite phase with respect to s(tp).
The transmitter as claimed in claim 5, wherein:
 denotes the phase rotation angle; and
1 = π - [arg(s(mod(tp - t + NFFT, NFFT))) - arg(s(tp))]; 2 = π - [arg(s(mod(tp + t, NFFT)) - arg(s(tp))]; and  = {|s (mod (tp+t, NFFT))| × 1 + |s(mod (tp-t+NFFT, NFFT))|× 2}/{|s(mod(tp-t+NFFT, NFFT)| + |s(mod (tp+t, NFFT))|}, where mod denotes a remainder operator; and
said shift amount determining part determines the shift amount so that a value calculated by the following formula may be equal to or more than a fixed value: Re{s(tp+t') × s(tp-t')/s(tp)2} where:
The transmitter as claimed in claim 3, comprising a plurality of the cyclic shifting parts, wherein:
The transmitter as claimed in claim 2, wherein:
said shift amount determining part determines a maximum shift amount according to the following requirements, when a scattered pilot signal is applied: ((the number of FFT points)/(pilot signal inserting interval)) ≥ (maximum shift amount) + (impulse response length),
based on an input channel impulse response and interval of the pilot signal in frequency direction..
The transmitter as claimed in claim 3, further comprising:
The transmitter as claimed in claim 3, comprising:
A transmission control method for a transmitter carrying out peak reduction processing, comprising the steps of:
a) generating an OFDM signal from an input information signal;
b) generating a signal cyclically shifted from the OFDM signal; and
c) adding the OFDM signal and the cyclically shifted signal together.
EP20050253100 2004-05-25 2005-05-19 Transmitter and transmission control method Active EP1601149B1 (en)
JP2004155032 2004-05-25
JP2004155032A JP4398791B2 (en) 2004-05-25 2004-05-25 Transmitter and transmission control method
EP1601149A2 true EP1601149A2 (en) 2005-11-30
EP1601149A3 EP1601149A3 (en) 2011-03-30
EP1601149B1 EP1601149B1 (en) 2013-06-26
ID=34979414
EP20050253100 Active EP1601149B1 (en) 2004-05-25 2005-05-19 Transmitter and transmission control method
US (1) US7463698B2 (en)
EP (1) EP1601149B1 (en)
JP (1) JP4398791B2 (en)
CN (1) CN1703037B (en)
EP2109227A1 (en) * 2007-03-06 2009-10-14 Huawei Technologies Co., Ltd. Method, device for reducing signal peak value and transmitting device
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JP4398791B2 (en) 2010-01-13
EP1601149B1 (en) 2013-06-26
EP1601149A3 (en) 2011-03-30
JP2005341055A (en) 2005-12-08
CN1703037B (en) 2011-05-11
US7463698B2 (en) 2008-12-09
US20050265479A1 (en) 2005-12-01
CN1703037A (en) 2005-11-30
CN102088436B (en) 2016-07-27 Guide based on multi-antenna communication system diversity ofdm
JP4140977B2 (en) 2008-08-27 Data transmission method and radio system
Inventor name: SUDA, HIROHITO C/O INTELLECTUAL PROPERTY DEPARTMEN
Inventor name: FUJII, HIROMASA C/O INTELLECTUAL PROPERTY DEPARTME
Inventor name: SHEN, JIYUN C/O INTELLECTUAL PROPERTY DEPARTMENT
Inventor name: ASAI, TAKAHIRO C/O INTELLECTUAL PROPERTY DEPARTMEN
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