JP4285845B2 - Receiver - Google Patents

Receiver Download PDF

Info

Publication number
JP4285845B2
JP4285845B2 JP21234799A JP21234799A JP4285845B2 JP 4285845 B2 JP4285845 B2 JP 4285845B2 JP 21234799 A JP21234799 A JP 21234799A JP 21234799 A JP21234799 A JP 21234799A JP 4285845 B2 JP4285845 B2 JP 4285845B2
Authority
JP
Japan
Prior art keywords
symbol
phase
symbols
amplitude
pilot
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
JP21234799A
Other languages
Japanese (ja)
Other versions
JP2001044963A (en
Inventor
健 宮野
Original Assignee
富士通テン株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 富士通テン株式会社 filed Critical 富士通テン株式会社
Priority to JP21234799A priority Critical patent/JP4285845B2/en
Publication of JP2001044963A publication Critical patent/JP2001044963A/en
Application granted granted Critical
Publication of JP4285845B2 publication Critical patent/JP4285845B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Images

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a receiving apparatus for digitally modulated signals, and more particularly to a receiving apparatus for digital terrestrial broadcasting, for example, using an orthogonal frequency division multiplexing system (hereinafter referred to as “OFDM system”) as a modulation system.
[0002]
[Prior art]
In terrestrial digital broadcasting, as shown in FIG. 1, the OFDM signal is composed of 13 segments, and synchronous modulation (eg, QPSK, 16QAM, 64QAM) is used for fixed reception as a subcarrier modulation method for each segment. Differential modulation (DQPSK) is used for mobile reception.
[0003]
Since the synchronous modulation section needs to know the absolute phase of the carrier wave, a reference signal (pilot symbol) whose value is known at the time of reception is drawn as shown in FIG.
As shown in FIG. 2, in the synchronous modulation section, pilot symbols are inserted at intervals of 12 carriers in one symbol, and data symbols in the vicinity of the pilot symbols are based on phase information obtained from the pilot symbols during fixed reception. Is representatively demodulated by the phase information of the pilot symbol, or a data symbol is demodulated in the frequency axis direction for each symbol. Therefore, fixed reception in which reception signal distortion does not occur in the time axis direction is a target.
[0004]
[Problems to be solved by the invention]
Since the data symbol of the differential modulation section can be received by differential demodulation, it is not necessary to know the absolute phase of the carrier wave and is suitable for mobile reception.
However, the synchronous modulation unit is a fixed reception target, but has a larger transmission capacity than the differential modulation unit. Therefore, the mobile body wants to receive the signal. However, the demodulation method that is representatively demodulated by the phase information of the pilot symbol is not sufficient to correct the signal distortion at the mobile body reception.
[0005]
In addition, regarding the mobile reception target of the differential modulation unit, the error rate characteristic is not good because it is differentially modulated.
Accordingly, an object of the present invention is to receive a signal of a synchronous modulation unit even with a mobile body and to improve reception quality of a differential modulation unit.
[0006]
[Means for Solving the Problems]
The receiving apparatus of the present invention is a receiving apparatus of, for example, a terrestrial digital broadcasting system using the OFDM system as a modulation system, and has a receiving unit for a synchronous modulation segment, and the receiving unit outputs an OFDM demodulated output for one frame. A frame memory for storing, a correction device for correcting the phase and amplitude of other symbols in the frame based on the distributed pilot symbols drawn in the stored frame, and a demodulating means for coherently demodulating the corrected output ing.
[0007]
The receiving means further includes a partial frame memory for storing symbols for a new four-symbol sequence in time among all the corrected symbols of one frame.
Then, the correction device, the phase and amplitude fluctuation value of the data symbols between the scattered pilot of the carrier shaft, wherein the scattered pilot symbols are present, primary or secondary Gaussian official at the interpolation based on the scattered pilot symbols To estimate and correct. Further, using the correction value of the carrier axis symbol in which the distributed pilot symbol exists, the phase / amplitude fluctuation value of the data symbol between the carrier axes is estimated by interpolation using a first-order or second-order Gaussian formula. to correct.
[0008]
Further, the receiving apparatus has receiving means for the differential modulation segment, and the receiving means is based on a symbol memory for storing an OFDM demodulated output for one symbol sequence, and a continuous pilot symbol inserted in the stored symbol sequence. A correction device for correcting the phase and amplitude of other symbols in the symbol string, and a demodulating means for coherently demodulating the corrected output.
[0009]
The receiving unit for the differential modulation segment also includes a differential demodulating unit for the differential modulation symbol , and a switching device for switching the output of the demodulating unit and the output of the coherent demodulating unit.
Then, the correction device estimates and corrects the phase / amplitude fluctuation value of the data symbol between consecutive pilot symbols of one symbol sequence by interpolation using a first-order or second-order Gaussian formula, and corrects the highest consecutive frequency. The phase / amplitude fluctuation value of the data symbol larger than the pilot symbol is estimated and corrected by complex division by the phase / amplitude estimation value of the continuous pilot symbol having the highest frequency.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
In the OFDM system, a bit string input in series is divided into predetermined unit blocks, and then converted into N parallel symbols that are phase and amplitude modulated. The N parallel symbols are multiplexed using subcarriers having different frequencies by inverse Fourier transform, and then added and transmitted. In this case, each subcarrier has mutual orthogonality.
[0011]
On the other hand, the receiving side of the OFDM communication system requires a transmission line equalizer that removes interference between samples in a symbol. In the transmission line equalizer, since each sample in the symbol has a different subcarrier, it is required to detect and remove the degree of distortion according to the changing transmission line condition.
In the OFDM system, there is a pilot symbol insertion method as an efficient transmission path equivalent method. According to the pilot symbol insertion method, when pilot symbols are transmitted periodically from the transmitting side, the receiving side knows when the pilot symbols are transmitted and decodes the transmitted pilot symbols and is distorted by the transmission path Is estimated. Then, the effective symbol distorted by the channel is compensated by the estimated value.
[0012]
As described above, FIG. 2 is a diagram showing the configuration of a frame in which pilot symbols for the synchronous modulation unit are inserted. Since the synchronous modulation section needs to know the absolute phase of the carrier wave, reference signals (pilot symbols) whose values are known are distributed and inserted at the time of reception (distributed pilot) as shown in FIG. In FIG. 2, the vertical axis represents the time axis and represents symbol (I), and the horizontal axis represents the frequency axis and represents carrier (K). One frame consists of 204 symbols. In the configuration shown in FIG. 2, pilot symbols are inserted every 12th carrier in the symbol along the frequency axis and every 3 carriers between adjacent symbols. And it inserts periodically and repeats every 4 symbols along the time axis. This configuration uses sampling theory and uses a minimum number of pilots and has a strong characteristic against the Doppler phenomenon.
[0013]
FIG. 3 is a diagram illustrating a frame configuration in which pilot symbols for the differential modulation unit are inserted. Since the differential modulation section puts information on the relative phase, it is not necessary to know the absolute phase. Therefore, although there is no distributed pilot as shown in FIG. 2, reference signals (pilot symbols) necessary for frequency synchronization are continuously inserted (continuous pilot). In the configuration shown in FIG. 3, pilot symbols are assigned to all of the carriers on the frequency axis.
[0014]
As described above, synchronous modulation is used for fixed reception, and differential modulation is used for mobile reception. In the synchronous modulation unit, one pilot symbol is inserted in 12 carriers in one symbol, and a considerable interval is opened. At the time of fixed reception, based on the phase information obtained from the pilot symbols, the data symbols near the pilot symbols are demodulated by representing the phase information of the pilot symbols. Alternatively, the symbols are demodulated in the frequency axis direction for each symbol. Therefore, fixed reception in which reception signal distortion does not occur in the time axis direction is a target.
[0015]
On the other hand, since the synchronous modulation unit has a larger transmission capacity than the differential modulation unit, the mobile unit wants to receive it. However, based on the phase information obtained from the pilot symbol, data symbols in the vicinity of the pilot symbol are used as the phase information of the pilot symbol. The method of demodulating as a representative is not sufficient to correct the signal distortion at the mobile reception.
FIG. 4 shows a signal space diagram of each modulation signal of the QPSK modulation signal. In the figure, if the symbol has a phase of 45 degrees (1, 1), if it is 3 times 45 degrees (1, 0), if it is 5 times 45 degrees (0, 0), if it is 7 times 45 degrees (0, 0) 1) is sent in accordance with the phase. In the case of fixed reception, the problem of fading does not occur, and such phase information can be received as it is. However, since fading occurs in the mobile body and the phase rotates, it may happen that the symbol that was (1, 1) at 45 degrees is shifted by, for example, 100 degrees on the receiving side.
[0016]
In FIG. 4, ● is a pilot symbol whose phase is found to be 45 degrees, and ○ is a data symbol whose phase is unknown unless demodulated on the receiving side. For example, it is assumed that when a pilot symbol ● whose phase is known on the receiving side is received, the phase is 100 degrees. In this case, 100 degrees−45 degrees = 55 degrees, and it can be seen that the phase is shifted by 55 degrees. However, when a data symbol ○ whose phase is unknown is received, it is not known how much the symbol is at the time of transmission. However, it is possible to correct the phase of another data symbol ◯ whose phase is not known with reference to the phase of the pilot symbol ● whose phase is known.
[0017]
For example, since it can be seen that the phase of the pilot symbol ● whose phase is known in FIG. 2 is shifted by 55 degrees, based on this phase shift, the data symbol ○ whose surrounding phase is unknown is corrected. can do. In that case, it is possible to correct the data symbol ○ whose phase immediately adjacent to the pilot symbol ● is not known accurately, but if the data symbol ○ is separated from the pilot symbol ●, for example, the moving object moves at high speed. In such a case, since the phase fluctuates during correction, it cannot be corrected accurately.
[0018]
However, since the synchronous modulation unit needs to know the absolute phase of the carrier wave, it needs to be corrected accurately.
Therefore, the present invention provides a receiving apparatus capable of sufficiently correcting signal distortion when received by a synchronous modulation unit in a mobile body.
FIG. 5 is a diagram for explaining a method for estimating and correcting phase / amplitude fluctuations according to the present invention. Among the symbols in the figure, the symbol ● (A, B, C) is a pilot symbol whose phase is known, and the symbol ◯ is a data symbol whose phase is unknown. In such a case, how to correct the phase of the data symbol whose phase is unknown based on the pilot symbol will be described.
[0019]
First, the known pilot symbols,
[0020]
[Expression 1]
[0021]
In the above equation, m is the symbol position as shown in FIG. 5, and N is the interval at which pilot symbols are inserted (in the case of FIG. 5, there is one for every four symbols, so N = 4).
In FIG. 5, A, B, and C are pilot symbols whose phase and amplitude are known, and x1, x2, and x3 are data symbols whose phase and amplitude are unknown. Similarly, y1, y2, y3, z1, and z2 are data symbols whose phase and amplitude are not known. Here, since the phases of two points of the pilot symbols A and B on both sides of the symbols x1, x2, and x3 are known, the estimated values of the phase and amplitude fluctuations are interpolated by the first order Gauss formula (6). Can be sought. In this case, Q 0 in equation (6) corresponds to symbol A and Q 1 corresponds to symbol B.
[0022]
Further, since the phase / amplitude of the three points of the pilot symbols A, B, and C is known for the data symbols y1, y2, and y3, the estimated values of these phase / amplitude fluctuations are expressed by the second order Gauss formula (5) It can be obtained by interpolation . In this case, Q −1 in Equation (5) corresponds to symbol A, Q 0 corresponds to symbol B, and Q 1 corresponds to symbol C. Note that the estimated values of the phase / amplitude fluctuations of x1, x2, and x3 can also be obtained by internal drawing using the quadratic Gauss formula (5) using pilot symbols A, B, and C whose phase and amplitude are known.
[0023]
Further, the data symbols z1 and z2 having a frequency higher than that of the pilot symbol C are estimated by performing complex division by the amplitude / phase estimation value of the pilot symbol C.
FIG. 6 is a diagram for explaining how to correct the phase and amplitude of symbols for one frame.
[0024]
[Table 1]
[0025]
As described above, since the differential modulation section puts information on the relative phase, it is not necessary to know the absolute phase. Therefore, although there is no distributed pilot as shown in FIG. 2, the frame configuration is a configuration in which reference signals (pilot symbols) necessary for frequency synchronization such as AFC are continuously inserted (continuous pilot) as shown in FIG. It has become. Since the symbol of the differential modulation unit can be received by differential demodulation, it is not necessary to know the absolute phase of the carrier wave and is suitable for mobile reception. However, since the differential modulation is performed, the error rate characteristic is deteriorated. Therefore, the present invention improves the reception quality of the differential modulation section.
[0026]
FIG. 7 is a diagram for explaining how to correct a symbol in the case of differential modulation. FIG. 7 shows one symbol of the frame configuration shown in FIG. First, the fluctuation values of the phase and amplitude of the symbols a, b, c, d, e between the continuous pilot symbol A having a low frequency and the continuous pilot symbol B having the next highest frequency are first Estimated by interpolation using Gauss formula. In addition, estimation is performed by performing complex division on all data symbols x, y, and z having a higher frequency than the continuous pilot symbol Z having the highest frequency by the amplitude / phase estimation value of the continuous pilot symbol Z having the highest frequency. To do. Further, the data symbols f, g, and h between B and C are estimated by interpolation using a quadratic Gauss formula based on the points A, B, and C. In addition, although the fluctuation value of the phase and amplitude of the symbol between A and B is estimated by the primary Gaussian formula, it can be estimated by the secondary Gaussian formula based on the pilot symbols A, B, and C. Further, although the data symbol between B and C is estimated by interpolation using a second-order Gauss formula, it can also be estimated using a first-order Gauss formula based on the B and C points. Note that the correction value can be obtained more accurately by using the secondary Gauss formula than the primary Gauss formula.
[0027]
Although details between C and Z are not described in detail, pilot symbols are inserted at predetermined intervals in the same manner as between A and C. Therefore, it can be estimated by interpolation using a first-order or second-order Gaussian formula, as between A and B or between B and C.
FIG. 8 is a block diagram of the configuration of the receiving apparatus of the present invention. Reference numeral 1 denotes an OFDM demodulator (FFT). The OFDM demodulated signal is output to the control device 2 of the synchronous modulation unit. A frame memory 3, a compensation device 4, and a partial frame memory 5 are connected to the control device 2. Then, the output of the control device 2 is input to the synchronous modulation carrier coherent demodulation unit 6 to perform coherent demodulation on the synchronous modulation segment.
[0028]
On the other hand, the OFDM demodulated signal is output to the control device 9 of the differential modulation section. A symbol memory 7 and a compensation device 8 are connected to the control device 9. Then, the output of the control device 9 is input to the differential modulation carrier coherent demodulation unit 10 to coherently demodulate the differential modulation segment.
The signal demodulated by the OFDM demodulator 1 is input to a differential modulation carrier differential demodulator 11 that performs normal differential demodulation. The outputs of the differential modulation carrier coherent demodulation unit 10 and the differential modulation carrier coherent differential demodulation unit 11 are output via the switching device 12.
[0029]
The operation of the receiving apparatus will be described below. First, the control device 2 of the synchronous modulation unit stores the output from the OFDM demodulation unit 1 in the frame memory 3 for one frame. Next, the compensator 4 estimates the phase of the symbol surrounded by the dotted line shown in FIG. 6 by interpolation according to the Gaussian formula based on the symbol whose phase and amplitude are known as described above. And apply this to the entire frame. Then, out of all symbols of one frame, symbols for four new symbol sequences in time are stored in the partial frame memory 4. As a result, the next frame can be estimated and corrected by interpolation using the second-order Gauss formula. The corrected symbol is input to the synchronous carrier coherent demodulation unit, demodulated and output.
[0030]
Further, the control unit 9 of the differential modulation unit stores the output from the OFDM demodulation unit 1 in the symbol memory 7 for one symbol string. Then, as described with reference to FIG. 7, one symbol is corrected by the compensation device 8. The corrected symbol is input to the differential carrier coherent demodulation unit, demodulated and output.
In general, DQPSK-modulated symbols are subjected to absolute phase detection, converted to natural codes, and differentially decoded to perform synchronous detection, thereby improving reception characteristics. In the present invention, the amplitude and phase of a differential modulation symbol are estimated by using continuous pilot symbols, so that synchronous detection is possible and reception characteristics are improved.
[0031]
The differential modulation carrier differential demodulation unit 11 is a differential decoding unit for normal differential modulation symbols, and switches between the output of the differential carrier coherent demodulation unit 10 and the output of the differential modulation carrier differential demodulation unit 11. It can be switched with. The insertion interval of continuous pilots is wide, and symbol amplitude and phase fluctuations cannot be sufficiently compensated during high-speed mobile reception. Therefore, by using the output of the differential carrier coherent demodulator 10 when the receiver is stationary or traveling at a very low speed, and using the output of the differential modulation carrier differential demodulator 11 at the time of high speed mobile reception, The reception quality can be improved.
[0032]
【The invention's effect】
According to the present invention, since the data symbol can be interpolated and estimated within the minimum range in which the distributed pilot exists in the synchronous modulation unit, the synchronous modulation unit having a larger amount of information than the differential modulation unit can be mobilely received. In addition, differential modulation symbols can be coherently demodulated using continuous pilot symbols, and further equipped with conventional differential demodulation means. Quality can be improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a segment configuration of an OFDM signal.
FIG. 2 is a diagram illustrating a frame configuration having a distributed pilot of a synchronous modulation unit.
FIG. 3 is a diagram illustrating a frame configuration having continuous pilots of a differential modulation unit.
FIG. 4 is a diagram showing a signal space diagram of each signal of a QPSK modulation signal.
FIG. 5 is a diagram for explaining a method of estimating a phase according to the present invention.
FIG. 6 is a diagram for explaining how to correct the phase of a symbol for one frame according to the present invention;
FIG. 7 is a diagram for explaining how to correct the phase of a symbol in the case of differential modulation according to the present invention;
FIG. 8 is a block diagram of a configuration of a receiving apparatus according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... OFDM demodulation part 2 ... Control apparatus 3 of synchronous modulation part ... Frame memory 4 ... Compensation apparatus 5 ... Partial frame memory 6 ... Synchronous modulation carrier coherent demodulation part 7 ... Symbol memory 8 ... Compensation apparatus 9 ... Control of differential modulation part Device 10 ... Differential modulation carrier coherent demodulation unit 11 ... Differential modulation carrier demodulation unit 12 ... Switching device

Claims (4)

  1. A receiving apparatus using an OFDM system as a modulation system, the receiving apparatus having a receiving unit for a synchronous modulation segment ,
    The receiving means stores a frame memory that stores the OFDM demodulated output for one frame, a compensation device that corrects the phase and amplitude of other symbols in the frame based on the distributed pilot symbols extracted in the stored frame, And coherent demodulation means for coherently demodulating the corrected output ,
    The compensator estimates, for each carrier in which a distributed pilot symbol exists, a phase / amplitude fluctuation value of a data symbol whose phase and amplitude exist between the distributed pilot symbols based on the distributed pilot symbol. The phase and amplitude of these data symbols are corrected, and for carriers for which the distributed pilot symbol does not exist, data whose phase and amplitude are not known based on the phase and amplitude of the distributed pilot symbol and the corrected data symbol. Estimate the fluctuation value of the phase and amplitude of the symbol and correct the phase and amplitude of these data symbols .
    The receiving device for the synchronous modulation segment further includes a partial frame memory for storing symbols for a new four-symbol sequence in time among all the corrected symbols of one frame.
  2. A receiving apparatus using an OFDM system as a modulation system, the receiving apparatus having receiving means for a differential modulation segment,
    The receiving means corrects the phase and amplitude of other symbols in the symbol sequence based on a symbol memory for storing the OFDM demodulated output for one symbol sequence, and a continuous pilot symbol extracted in the stored symbol sequence. A compensation device, and coherent demodulation means for coherently demodulating the corrected output,
    The compensator estimates and corrects a phase / amplitude variation value of a data symbol between consecutive pilot symbols of one symbol sequence by estimating by interpolation using a first-order or second-order Gauss formula based on the continuous pilot symbols. A receiving apparatus that estimates and corrects a phase / amplitude fluctuation value of a data symbol larger than the highest consecutive pilot symbol by complex division by a phase / amplitude estimated value of the highest consecutive pilot symbol of the frequency.
  3. Receiving means for said differential modulation segment also includes differential demodulation means for differential modulation symbols, comprising a switching device that switches and outputs the output of said coherent demodulating means and the output of the demodulation means, according to claim 2 Receiver.
  4. The receiving device according to claim 3 , wherein the switching device switches the output according to a moving state of the receiver.
JP21234799A 1999-07-27 1999-07-27 Receiver Expired - Fee Related JP4285845B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP21234799A JP4285845B2 (en) 1999-07-27 1999-07-27 Receiver

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP21234799A JP4285845B2 (en) 1999-07-27 1999-07-27 Receiver

Publications (2)

Publication Number Publication Date
JP2001044963A JP2001044963A (en) 2001-02-16
JP4285845B2 true JP4285845B2 (en) 2009-06-24

Family

ID=16621043

Family Applications (1)

Application Number Title Priority Date Filing Date
JP21234799A Expired - Fee Related JP4285845B2 (en) 1999-07-27 1999-07-27 Receiver

Country Status (1)

Country Link
JP (1) JP4285845B2 (en)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4171261B2 (en) 2001-08-27 2008-10-22 松下電器産業株式会社 Wireless communication apparatus and wireless communication method
KR100510551B1 (en) * 2003-10-10 2005-08-26 삼성전자주식회사 OFDM demodulator with common phase error(CPE) correction and CPE removing method
JP2006352746A (en) * 2005-06-20 2006-12-28 Fujitsu Ltd Receiver for orthogonal frequency division multiplexing transmission
WO2008050428A1 (en) * 2006-10-26 2008-05-02 Fujitsu Limited Radio base station apparatus, pilot transmitting method thereof and terminal apparatus
KR101395686B1 (en) 2007-06-29 2014-05-15 톰슨 라이센싱 Apparatus and method for removing common phase error in a dvb-t/h receiver
EP2165493B1 (en) * 2007-06-29 2013-04-17 Thomson Licensing Apparatus and method for removing common phase error in a DVD-T/H receiver
JP5441811B2 (en) * 2010-04-27 2014-03-12 シャープ株式会社 Receiving device, base station device, wireless communication system, propagation path estimation method, control program, and integrated circuit
JP5327292B2 (en) * 2011-08-29 2013-10-30 富士通株式会社 Wireless communication system

Also Published As

Publication number Publication date
JP2001044963A (en) 2001-02-16

Similar Documents

Publication Publication Date Title
DE69730283T2 (en) Method and device for the common estimation of frequency shifting and synchronization in a multi-feed modulation system
CN101960810B (en) System and methods for receiving OFDM symbols having timing and frequency offsets
DE60320615T2 (en) Multi-carrier reception with detection of interference
KR100714767B1 (en) Apparatus, and associated Method, for effectuating POST-FFT correction of fine frequency offset
Schmidl et al. Low-overhead, low-complexity [burst] synchronization for OFDM
US7646747B2 (en) Channel constructing method and base station using the method
EP1172982B1 (en) Carrier recovery in a multicarrier receiver
KR100581780B1 (en) Orthogonal frequency-division multiplex transmission system, and its transmitter and receiver
US7009931B2 (en) Synchronization in a multiple-input/multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) system for wireless applications
KR100807886B1 (en) Receiver of orthogonal frequency division multiple system
US7724694B2 (en) Doppler frequency calculating apparatus and method and OFDM demodulating apparatus
US7463577B2 (en) OFDM communication method and OFDM communication device
KR100865938B1 (en) Apparatus for Estimating and Compensating Carrier Frequency Offset and Data Receiving Method in Receiver of Wireless Communication System
JP4870096B2 (en) Multi-carrier modulation method and transmitter and receiver using the method
US6940932B2 (en) Diversity receiver
US7664189B2 (en) OFDM demodulator, receiver, and method
US7061997B1 (en) Method and apparatus for fine frequency synchronization in multi-carrier demodulation systems
DE602004006406T2 (en) Frequency synchronization device and frequency synchronization process
JP3678119B2 (en) OFDM communication system and base station and terminal used in the communication system
EP1335552B1 (en) Estimation of channel response and of delay in multicarrier systems
US10277369B2 (en) Receiver and method of receiving
EP1207663B1 (en) Signal quality assessment in a multicarrier receiver
JP4149044B2 (en) Method and circuit apparatus for correcting phase and / or frequency error of digital multi-carrier signal
US7885360B2 (en) Wireless communication apparatus and receiving method
US6850481B2 (en) Channels estimation for multiple input—multiple output, orthogonal frequency division multiplexing (OFDM) system

Legal Events

Date Code Title Description
A521 Written amendment

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20060726

A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20060727

A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20080922

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20081202

A521 Written amendment

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20090128

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20090224

A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20090324

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20120403

Year of fee payment: 3

R150 Certificate of patent or registration of utility model

Free format text: JAPANESE INTERMEDIATE CODE: R150

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20120403

Year of fee payment: 3

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20130403

Year of fee payment: 4

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20130403

Year of fee payment: 4

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20140403

Year of fee payment: 5

LAPS Cancellation because of no payment of annual fees