CN101547175B - Method and system for correcting residual deviation of sampling frequency in OFDM systems - Google Patents
Method and system for correcting residual deviation of sampling frequency in OFDM systems Download PDFInfo
- Publication number
- CN101547175B CN101547175B CN2009100821835A CN200910082183A CN101547175B CN 101547175 B CN101547175 B CN 101547175B CN 2009100821835 A CN2009100821835 A CN 2009100821835A CN 200910082183 A CN200910082183 A CN 200910082183A CN 101547175 B CN101547175 B CN 101547175B
- Authority
- CN
- China
- Prior art keywords
- frequency
- symbol
- mapping
- ofdm
- slope
- 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.)
- Active
Links
- 238000005070 sampling Methods 0.000 title claims abstract description 45
- 238000000034 method Methods 0.000 title claims abstract description 25
- 238000013507 mapping Methods 0.000 claims description 39
- 238000002715 modification method Methods 0.000 claims description 13
- 238000012937 correction Methods 0.000 claims description 7
- 238000004891 communication Methods 0.000 abstract description 4
- 230000001419 dependent effect Effects 0.000 description 9
- 238000009825 accumulation Methods 0.000 description 3
- 230000009897 systematic effect Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 230000008717 functional decline Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
Images
Landscapes
- Synchronisation In Digital Transmission Systems (AREA)
Abstract
The invention discloses a method and a system for correcting residual deviation of sampling frequency in OFDM systems, which belongs to the OFDM technical field in the field of wireless communication. The method comprises the following steps: removing modulation information carried by currently received OFDM symbols in each frequency domain at a receiving end; selecting a plurality of frequency points from the OFDM symbols of which the modulation information is removed and calculating phase curves of the selected frequency points and the slope of the phase curves; correcting a channel estimation value according to the slope of the phase curves; and utilizing the corrected channel estimation value to equalize a next received OFDM symbol. The invention has the advantages of avoiding the bit-error performance drop of the systems, which is caused by initial sampling-frequency deviation estimation, corrected error and the own error of sampling clocks, effectively reducing the bit error rate of the systems and improving the performance of the OFDM systems.
Description
Technical field
The invention relates to OFDM (Orthogonal Frequency Division Multiplexing, the OFDM) technology in the wireless communication field, be specifically related to the modification method and the system of residual deviation of sampling frequency in a kind of ofdm system.
Background technology
In practical communication system, transmitting terminal D/A converter and receiving terminal A/D converter adopt clock separately respectively, make to send between signal and the received signal to have sampling frequency deviation.Sampling frequency deviation makes on the one hand and receives the deflection of data generation phase place, has also destroyed the orthogonality between subcarrier on the other hand, makes a big impact to being correctly decoded, and this requires sampling frequency deviation made estimates accurately and revise.
In ofdm communication system, the estimation of sampling frequency deviation and correction are normally carried out in time domain.Yet if only do the estimation and the correction of a sampling frequency deviation in time domain, if estimate or deviation is arranged slightly when revising, along with the accumulation of time, this deviation can be increasing, finally still can cause very big error code, makes systematic function decline; Perhaps because sampling clock generation little deviation affected by environment, but, also can make deviation increasing, can cause very big error code to system equally along with the accumulation of time.Therefore, must after the estimation of finishing a sampling frequency deviation and revising, do further tracking, the influence that causes with continuous elimination sampling frequency deviation.
Summary of the invention
The present invention has overcome deficiency of the prior art, and the modification method and the system of residual deviation of sampling frequency in a kind of ofdm system is provided, and can reduce the error rate of system effectively, improves systematic function.
Technical scheme of the present invention is:
The modification method of sampling clock frequency offset in a kind of ofdm system, its step comprises:
1), removes the modulation intelligence that each frequency-domain OFDM symbol of current reception carries at receiving terminal;
2) in the OFDM of above-mentioned removal modulation intelligence symbol, choose a plurality of frequencies, and the frequency of choosing is calculated the slope of phase curve and phase curve;
3) according to the slope of above-mentioned phase curve, channel estimation value is revised;
4) utilize revised channel estimation value that the OFDM symbol that the next one receives is carried out equilibrium.
The concrete steps of removing modulation intelligence in the described step 1) are: the binary sequence of the receiving terminal constellation being separated mapping is remapped to symbol sebolic addressing, the mapping mode of each OFDM symbol is corresponding with its mode of separating mapping, afterwards, find the solution separate mapping before, the symbol after the equilibrium with remap accordingly after phase place poor of symbol.
The concrete steps of removing modulation intelligence in the described step 1) can also be binary sequence after the receiving terminal constellation separated mapping and carry out channel-decoding, again carry out corresponding chnnel coding and be mapped as symbol sebolic addressing, and the mapping mode of each OFDM symbol is corresponding with its mode of separating mapping, afterwards, find the solution separate mapping before, the symbol after the equilibrium with remap accordingly after phase place poor of symbol.
Described step 2) frequency of choosing in is the frequency of the intermediate frequency band in the frequency-domain OFDM symbol, and the center frequency point of the positive and negative Frequency point of choosing is about the zero-frequency symmetry.
The slope value of phase curve described step 2) is calculated as, deduct the ordinate value of each point of corresponding negative frequency respectively with the ordinate value of each point of positive frequency, and then, obtain the slope value of phase curve thus respectively divided by the abscissa spacing between them.
The method of in the described step 3) channel estimation value being revised is: H
New=H
Old* e
J (ξ k), wherein, H
OldBe channel estimation value once balanced before being used for, H
NewFor being about to be used for the current data symbol is carried out balanced channel estimation value, ξ is a slope, and k is the frequency domain sequence number of each subcarrier in the OFDM symbol.
Adopt the method for feedback loop in the described step 4), utilize the good channel estimation value of current correction that the next OFDM symbol that receives is carried out equilibrium, thereby form feedback control loop.
The update the system of residual deviation of sampling frequency in a kind of ofdm system, this system comprises:
One removes the modulation intelligence module, is used for removing modulation intelligence at the ofdm system receiving terminal;
One chooses preferred frequency module, is used for choosing a plurality of preferred frequencies at each frequency-domain OFDM symbol;
One residual deviation of sampling frequency estimation module is used for preferred frequency is calculated phase curve, and obtains the slope of this phase curve;
One channel estimating correcting module according to the slope of above-mentioned phase curve, is revised channel estimation value;
With a feedback loop balance module, the OFDM symbol that the next one is received carries out equilibrium.
The constellation of described removal modulation intelligence module reception ofdm system receiving terminal is separated the signal of mapping block.Or described removal modulation intelligence module receives the signal of the channel decoding module of ofdm system receiving terminal.
Compared with prior art, the invention has the beneficial effects as follows:
The present invention proposes the modification method and the system of sampling instant offset in a kind of ofdm system.This method is estimated residual deviation of sampling frequency in the receiving terminal frequency domain, further utilize this offset that channel estimation value is revised, and the method that adopts feedback loop is used for current correction value the equilibrium of next OFDM symbol, thereby avoided owing to begin the influence that sampling frequency deviation is estimated and the error of the error of correction and sampling clock itself causes system's error performance to descend most, reduce the error rate of system effectively, improved systematic function.
Description of drawings
Fig. 1 residual deviation of sampling frequency update the system of the present invention block diagram;
Fig. 2 adopts system's planisphere of residual deviation of sampling frequency modification method of the present invention;
Fig. 3 does not adopt system's planisphere (a) of residual deviation of sampling frequency modification method of the present invention;
Fig. 4 does not adopt system's planisphere (b) of residual deviation of sampling frequency modification method of the present invention;
Fig. 5 does not adopt system's planisphere (c) of residual deviation of sampling frequency modification method of the present invention.
Embodiment
Below in conjunction with the drawings and specific embodiments the present invention is described in further detail:
With reference to figure 1, existing OFDM receiving terminal comprises that sampling frequency deviation corrects module 1, OFDM demodulation module 2, constellation and separate mapping block 4 and channel decoding module 5, the present invention comprises at the update the system that the OFDM receiving terminal carries out residual deviation of sampling frequency: one removes the modulation intelligence module, is used for removing modulation intelligence at the ofdm system receiving terminal; One chooses preferred frequency module, is used for choosing a plurality of preferred frequencies at each frequency-domain OFDM symbol; One residual deviation of sampling frequency estimation module is used for preferred frequency is calculated phase curve, and obtains the slope of this phase curve; One channel estimating correcting module according to the slope of above-mentioned phase curve, is revised channel estimation value; With a feedback loop balance module, the OFDM symbol that the next one is received carries out equilibrium.
Removing the modulation intelligence module removes the method for modulation intelligence and be: the binary sequence of the receiving terminal constellation being separated mapping is remapped to symbol sebolic addressing, and to separate the mode of hinting obliquely at corresponding with it for the mapping mode of each OFDM symbol.Afterwards, find the solution before separating mapping, the symbol after the equilibrium with remap accordingly after phase place poor of symbol, can remove modulation intelligence like this.The method of removing modulation intelligence also can be: the binary sequence after the receiving terminal constellation is separated mapping and carried out channel-decoding, again carry out corresponding chnnel coding and be mapped as symbol sebolic addressing, and the mapping mode of each OFDM symbol is corresponding with its mode of separating mapping.Afterwards, find the solution separate mapping before, the symbol after the equilibrium with remap accordingly after phase place poor of symbol.The difference of this phase place has two kinds of method for solving: a kind of is that both phase places are directly subtracted each other; Another kind is that both do conjugate multiplication or directly are divided by, and asks the phase place of operation result then.
Choosing preferred frequency module chooses the principle of preferred frequency and is: in each frequency-domain OFDM symbol, owing to all be interfered easily near edge band and the zero-frequency, therefore will not select them, and select the frequency of intermediate frequency band.Usually, the choosing method of preferred frequency is varied, as long as can utilize these preferred frequencies to calculate the dependent phase slope of a curve accurately as far as possible.Such as, can select to be positioned at M/2 continuity point of positive frequency intermediate frequency band and M/2 continuity point of negative frequency intermediate frequency band, M is approximately about half of effective subcarrier number, and the point of the positive negative frequency of choosing is about the zero-frequency symmetry.
The dependent phase curve of each the OFDM symbol when removing modulation intelligence should be straight line in the ideal case, but owing to be subjected to the various interference of undesirable channel, the dependent phase curve approximation is a straight line, and its slope is exactly a residual deviation of sampling frequency.Here, the residual deviation of sampling frequency estimation module asks the method for slope can have multiple.For example, if preferred frequency is according to the method described above, promptly select to be positioned at M/2 continuity point of positive frequency intermediate frequency band and M/2 continuity point of negative frequency intermediate frequency band, and the point of the positive negative frequency of choosing is about the zero-frequency symmetry, can deduct the ordinate value of each point of corresponding negative frequency so with the ordinate value of each point of positive frequency respectively, and then respectively divided by the abscissa spacing between them, obtain M/2 slope value thus, again this M/2 slope value is averaged, can be similar to and obtain the dependent phase slope of a curve; Also can deduct the ordinate value sum of all preferred negative Frequency points earlier with the ordinate value sum of all preferred positive frequency points, poor divided by the center of preferred positive frequency point and preferred negative Frequency point also can be similar to and obtain the dependent phase slope of a curve again.In addition, also have other to ask the method for slope; The mode difference of selected preferred frequency asks the method for slope also different.
The method that the channel estimating correcting module is revised channel estimation value is: H
New=H
Old* e
J (ξ k)Wherein, H
OldBe channel estimation value once balanced before being used for, H
NewFor being about to be used for the current data symbol is carried out balanced channel estimation value, ξ is a slope, and k is the frequency domain sequence number of each subcarrier in the OFDM symbol.Channel estimation value is constantly being revised always, current revised H
NewCan become the H when next time revising
Old
Balance module adopts the method for feedback loop, utilizes the good channel estimation value of current correction that the next OFDM symbol that receives is carried out equilibrium, thereby forms feedback control loop.
The modification method that OFDM receiving terminal of the present invention carries out residual deviation of sampling frequency is specially:
At first, the data or the data behind the channel-decoding of constellation being separated after the mapping are removed modulation intelligence.If constellation is just removed modulation intelligence after separating mapping, then remove modulation intelligence module 6 and be connected on A point place among Fig. 1, and the binary character that only needs to separate mapping when removing modulation intelligence is remapped to constellation symbol again according to separating mapping mode, and then make relevantly of the balanced data symbol and the corresponding points of this constellation symbol, can obtain one group of dependent phase; Just remove modulation intelligence if carried out channel-decoding again after constellation is separated and shone upon, then remove modulation intelligence module 6 and need be connected on B point place among Fig. 1, binary character with B point place carries out corresponding chnnel coding more then, and corresponding constellation mapping, again become constellation symbol again, make relevantly again of the balanced data symbol and the corresponding points of this constellation symbol, obtain one group of dependent phase.
Afterwards, choose preferred frequency module 7, in one group of dependent phase after removing modulation intelligence, select preferred frequency wherein according to selection principle.In the residual deviation of sampling frequency estimation module 8 of Fig. 1, utilize above-mentioned preferred frequency to calculate dependent phase slope of a curve, i.e. residual deviation of sampling frequency value.Then, channel estimating correcting module 9 utilizes the residual deviation of sampling frequency that calculates that channel estimation value is revised again.According to revised channel estimation value, 3 pairs of follow-up OFDM symbols of balance module carry out equilibrium at last.
The whole flow process of residual deviation of sampling frequency modification method of the present invention has formed a feedback control loop, like this can be in the frequency domain of OFDM receiving terminal, the offset of continuous tracking sampling frequency, and utilize this deviation constantly channel estimation value to be revised, each is done balanced OFDM symbol and all uses current up-to-date channel estimation value to carry out equilibrium.
The planisphere that adopts residual deviation of sampling frequency update the system of the present invention as shown in Figure 2, the 64QAM constellation mapping is adopted in the emulation of this figure, has shown 15000 data symbolic points among the figure, as can be seen, the planisphere effect is very good, and this planisphere noise is about 42dB.And do not adopt planisphere such as Fig. 3 of residual deviation of sampling frequency update the system of the present invention---shown in Figure 5, wherein Fig. 3 emulation 5000 data symbolic points, Fig. 4 emulation 10000 data symbolic points, Fig. 5 emulation 15000 points, all the other simulated conditions are the same with Fig. 2 all.From Fig. 3---as can be seen, very big rotation has taken place in planisphere Fig. 5, and slightly diffusion; Along with the accumulation of time, i.e. increasing of data symbol point, the anglec of rotation is increasing.When data symbol count with Fig. 2 in identical, when also being at 15000, be difficult to correct demodulation, and the planisphere signal to noise ratio of this moment dropped to about 19dB, reduced dB more than 20 than the signal to noise ratio that adopts residual deviation of sampling frequency update the system of the present invention.This shows, the present invention can effectively reduce residual deviation of sampling frequency along with time integral to the influence that system caused, have good practicality.
More than by specific embodiment the residual deviation of sampling frequency modification method and the system of ofdm system provided by the present invention have been described, those skilled in the art is to be understood that, in the scope that does not break away from essence of the present invention, can make certain deformation or modification to the present invention; Its preparation method also is not limited to disclosed content among the embodiment.
Claims (6)
1. the modification method of sampling clock frequency offset in the ofdm system, its step comprises:
1), removes the modulation intelligence that each frequency-domain OFDM symbol of current reception carries at receiving terminal; Its method is: the binary sequence of the receiving terminal constellation being separated mapping is remapped to symbol sebolic addressing, the mapping mode of each OFDM symbol is corresponding with its mode of separating mapping, afterwards, find the solution separate mapping before, the symbol after the equilibrium with remap accordingly after phase place poor of symbol; Perhaps, the receiving terminal constellation separated mapping and carry out binary sequence behind the channel-decoding, again carry out corresponding chnnel coding and be mapped as symbol sebolic addressing, and the mapping mode of each OFDM symbol is corresponding with its mode of separating mapping, afterwards, find the solution separate mapping before, the symbol after the equilibrium with remap accordingly after phase place poor of symbol;
2) in the OFDM of above-mentioned removal modulation intelligence symbol, choose a plurality of frequencies, and the frequency of choosing is calculated the slope of phase curve and phase curve;
3) according to the slope of above-mentioned phase curve, channel estimation value is revised;
4) utilize revised channel estimation value that the OFDM symbol that the next one receives is carried out equilibrium.
2. the method for claim 1 is characterized in that, described step 2) in the frequency chosen be the frequency of the intermediate frequency band in the frequency-domain OFDM symbol, and the center frequency point of the positive and negative Frequency point of choosing is about the zero-frequency symmetry.
3. method as claimed in claim 2, it is characterized in that, the slope value of phase curve described step 2) is calculated as, deduct the ordinate value of each point of corresponding negative frequency respectively with the ordinate value of each point of positive frequency, and then, obtain the slope value of phase curve thus respectively divided by the abscissa spacing between them.
4. the method for claim 1 is characterized in that, the method for in the described step 3) channel estimation value being revised is: H
New=H
Old* e
J (ξ k), wherein, H
OldBe channel estimation value once balanced before being used for, H
NewFor being about to be used for the current data symbol is carried out balanced channel estimation value, ξ is a slope, and k is the frequency domain sequence number of each subcarrier in the OFDM symbol.
5. method as claimed in claim 4 is characterized in that, adopts the method for feedback loop in the described step 4), utilizes the good channel estimation value of current correction that the next OFDM symbol that receives is carried out equilibrium, thereby forms feedback control loop.
6. the update the system of residual deviation of sampling frequency in the ofdm system, this system comprises:
One removes the modulation intelligence module, described removal modulation intelligence module is remapped to symbol sebolic addressing by the binary sequence of the receiving terminal constellation being separated mapping, the mapping mode of each OFDM symbol is corresponding with its mode of separating mapping, afterwards, find the solution separate mapping before, the symbol after the equilibrium with remap accordingly after phase place poor of symbol; Perhaps, by the binary sequence after the receiving terminal constellation being separated mapping and being carried out channel-decoding, again carry out corresponding chnnel coding and be mapped as symbol sebolic addressing, and the mapping mode of each OFDM symbol is corresponding with its mode of separating mapping, afterwards, find the solution separate mapping before, the symbol after the equilibrium with remap accordingly after phase place poor of symbol; Thereby remove modulation intelligence at the ofdm system receiving terminal;
One chooses preferred frequency module, is used for choosing a plurality of preferred frequencies at each frequency-domain OFDM symbol;
One residual deviation of sampling frequency estimation module is used for preferred frequency is calculated phase curve, and obtains the slope of this phase curve;
One channel estimating correcting module according to the slope of above-mentioned phase curve, is revised channel estimation value;
With a feedback loop balance module, the OFDM symbol that the next one is received carries out equilibrium.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009100821835A CN101547175B (en) | 2009-04-17 | 2009-04-17 | Method and system for correcting residual deviation of sampling frequency in OFDM systems |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009100821835A CN101547175B (en) | 2009-04-17 | 2009-04-17 | Method and system for correcting residual deviation of sampling frequency in OFDM systems |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101547175A CN101547175A (en) | 2009-09-30 |
| CN101547175B true CN101547175B (en) | 2011-07-20 |
Family
ID=41194067
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2009100821835A Active CN101547175B (en) | 2009-04-17 | 2009-04-17 | Method and system for correcting residual deviation of sampling frequency in OFDM systems |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN101547175B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102263719B (en) * | 2010-05-24 | 2014-04-09 | 中兴通讯股份有限公司 | Frequency offset compensating and balancing method and device for orthogonal frequency division multiplexing system |
| CN102340810B (en) * | 2011-09-22 | 2015-03-04 | 大唐移动通信设备有限公司 | Equipment stability testing method and device |
| CN103856418B (en) * | 2012-12-04 | 2018-04-06 | 中兴通讯股份有限公司 | Anti- sampling deviation treating method and apparatus in wireless communication system channel estimation |
| CN103248596A (en) * | 2013-05-16 | 2013-08-14 | 北京大学 | Combined amending method and system for residual time frequency offset in OFDM (orthogonal frequency division multiplexing) system |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1677908A (en) * | 2004-03-31 | 2005-10-05 | 清华大学 | TDS-OFDM receiver self-adaptive channel estimation balancing method and system |
| CN1797988A (en) * | 2004-12-28 | 2006-07-05 | 索尼株式会社 | Radio communication equipment and communication method |
| CN1848834A (en) * | 2005-09-13 | 2006-10-18 | 威盛电子股份有限公司 | Averaging circuit for enhancing channel estimation in receptor and compensating frequency offset residue |
| CN1881970A (en) * | 2005-06-13 | 2006-12-20 | 北京中电华大电子设计有限责任公司 | Method and apparatus for compensating sampling frequency offset and carrier frequency offset in OFDM system |
-
2009
- 2009-04-17 CN CN2009100821835A patent/CN101547175B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1677908A (en) * | 2004-03-31 | 2005-10-05 | 清华大学 | TDS-OFDM receiver self-adaptive channel estimation balancing method and system |
| CN1797988A (en) * | 2004-12-28 | 2006-07-05 | 索尼株式会社 | Radio communication equipment and communication method |
| CN1881970A (en) * | 2005-06-13 | 2006-12-20 | 北京中电华大电子设计有限责任公司 | Method and apparatus for compensating sampling frequency offset and carrier frequency offset in OFDM system |
| CN1848834A (en) * | 2005-09-13 | 2006-10-18 | 威盛电子股份有限公司 | Averaging circuit for enhancing channel estimation in receptor and compensating frequency offset residue |
Also Published As
| Publication number | Publication date |
|---|---|
| CN101547175A (en) | 2009-09-30 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US8774034B2 (en) | Method and apparatus for frequency offset estimation and correction in orthogonal frequency division multiplexing system | |
| US8428165B2 (en) | Method and system for decoding OFDM signals subject to narrowband interference | |
| EP1367789B1 (en) | Transmission apparatus, reception apparatus, transmission method and reception method | |
| EP2429139A2 (en) | Signal receiving apparatus, signal receiving method and signal receiving program | |
| JP5557402B2 (en) | Apparatus and method for compensating for phase error in a cordless communication system | |
| CN107438047B (en) | Phase noise self-correction compensation method based on decision feedback in single carrier frequency domain equalization system | |
| JP2001077788A (en) | Transmitter, receiver, communication system, transmitting method, receiving method and communication method | |
| CN102882652B (en) | M-APSK (amplitude phase shift keying) signal to noise estimation method based on iterative decoding and decision feedback | |
| CN101394381A (en) | Self-adaptive equalizer for phase noise compensation | |
| CN101547175B (en) | Method and system for correcting residual deviation of sampling frequency in OFDM systems | |
| US8649465B2 (en) | Methods and apparatuses for adaptive clock reconstruction and decoding in audio frequency communication | |
| KR20070090800A (en) | Apparatus and method for channel estimation in wireless communication system | |
| CN101577581B (en) | Channel estimation method | |
| US9031170B2 (en) | Channel frequency response estimator for a wireless RF channel | |
| CN111107028B (en) | PSS and SSS combined frequency offset estimation method for 5G system | |
| JPWO2008099572A1 (en) | Receiving apparatus and receiving method | |
| CN103248596A (en) | Combined amending method and system for residual time frequency offset in OFDM (orthogonal frequency division multiplexing) system | |
| JP5532055B2 (en) | Wireless communication apparatus, wireless communication system, and wireless communication method | |
| WO2008069556A1 (en) | Amplitude-differential phase shift keying modulation apparatus and method | |
| WO2007065045A2 (en) | Method and apparatus for improving recovery performance of time windowed signals | |
| CN107666456B (en) | Receiver circuit | |
| CN101577689B (en) | Method for detecting and correcting residual frequency offset of national standard of digital terrestrial broadcasting | |
| US8750397B2 (en) | Apparatus and method for channel estimation in wireless communication system | |
| CN114747185B (en) | Non-zero insertion based modulation scheme for low peak-to-average power ratio | |
| KR20080099086A (en) | Apparatus and method for estimating channel in ofdm/ofdma system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| EE01 | Entry into force of recordation of patent licensing contract | ||
| EE01 | Entry into force of recordation of patent licensing contract |
Application publication date: 20090930 Assignee: BEIJING HANNUO SEMICONDUCTOR TECHNOLOGY CO., LTD. Assignor: Peking University|Beijing three ladder network technology Co., Ltd. Contract record no.: 2017990000150 Denomination of invention: Method and system for correcting residual deviation of sampling frequency in OFDM systems Granted publication date: 20110720 License type: Exclusive License Record date: 20170425 |