CN101547062B - Method and device for correcting frequency deviation - Google Patents

Method and device for correcting frequency deviation Download PDF

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Publication number
CN101547062B
CN101547062B CN2009100791581A CN200910079158A CN101547062B CN 101547062 B CN101547062 B CN 101547062B CN 2009100791581 A CN2009100791581 A CN 2009100791581A CN 200910079158 A CN200910079158 A CN 200910079158A CN 101547062 B CN101547062 B CN 101547062B
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frequency deviation
grouped data
frequency
described user
offset estimation
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CN101547062A (en
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秦一平
蒋培刚
吴和兵
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Huawei Technologies Co Ltd
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Huawei Technologies Co Ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2657—Carrier synchronisation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2668—Details of algorithms
    • H04L27/2673—Details of algorithms characterised by synchronisation parameters
    • H04L27/2675—Pilot or known symbols

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Abstract

The embodiment of the invention discloses a method and a device for correcting frequency deviation, which belong to the field of communication. The method comprises the following steps: receiving current grouped data, and acquiring frequency domain data and pilot frequency data of a user in the current grouped data according to the received current grouped data; acquiring a frequency deviation estimation result of the user in the current grouped data according to the pilot frequency data of the user in the current grouped data and a frequency deviation correction result of the user in the grouped data after the frequency deviation correction; and correcting the frequency deviation of the frequency domain data of the user in the current grouped data according to the frequency deviation estimation result. The device comprises a receiving module, an acquiring module and a frequency deviation correction module. By adopting the feedback of the frequency deviation correction result of the user in the grouped data after the frequency deviation correction, the frequency deviation correction result of the user in the current grouped data is acquired, and the complexity of AFC is greatly reduced.

Description

The correcting frequency deviation method and apparatus
Technical field
The present invention relates to the communications field, particularly a kind of correcting frequency deviation method and apparatus.
Background technology
3GPP (3rd Generation Partnership Project, third generation partner program) in, LTE (Long Term Evolution, Long Term Evolution) project is the new technology development project of the maximum of over the past two years 3GPP startup, this with OFDM (Orthogonal Frequency Division Multiple Access, OFDM)/FDMA (Frequency Division Multiple Access, frequency division multiplexing) can be counted as " accurate 4G " technology for the technology of core.
OFDM is a kind of of MCM (Multi-Carrier Modulation, multi-carrier modulation).Its main thought is: channel is divided into some orthogonal sub-channels, converts high-speed data signal to parallel low speed sub data flow, be modulated on every sub-channels and transmit.Orthogonal signalling can separately can be reduced like this phase mutual interference between the subchannel by adopt correlation technique at receiving terminal.Signal bandwidth on every sub-channels is less than the correlation bandwidth of channel, and therefore the flatness of can regarding as on every sub-channels declines, thereby can eliminate intersymbol interference.And because the bandwidth of every sub-channels only is the sub-fraction of former channel width, it is relatively easy that channel equalization becomes.OFDM can in conjunction with diversity, space-time code, interference and interchannel interference inhibition and intelligent antenna technology, improve systematic function to greatest extent.But OFDM is comparatively responsive to frequency shift (FS), and the frequency shift (FS) meeting causes the time domain sampling point to produce phase rotating, makes to have phase deviation between the different OFDM symbols, also can destroy simultaneously the orthogonality between the ofdm system subcarrier, thus degrade demodulation performance.Therefore, need to estimate frequency shift (FS).
AFC of the prior art (Automatic Frequency Correction, auto frequency deviation is corrected) method, adopt CP (Cyclic Prefix, Cyclic Prefix) frequency deviation to estimate in conjunction with the method that the pilot reference signal frequency deviation is estimated frequency shift (FS) to be estimated.Wherein, the CP of time domain is by DFT (Discrete Fourier Transform, discrete Fourier transform (DFT)) isolates user's frequency-region signal, just can obtain corresponding frequency deviation with the phase place difference between the frequency domain data of FFT (Fast Fourier Transform, fast fourier transform) symbolic component in this OFDM symbol of user.Repeat because CP is the part of data FFT symbol, and the part of CP part and Data duplication is separated by not quite in time domain, utilizes this repeat property can contain larger frequency deviation region.
In realizing process of the present invention, the inventor finds that above-mentioned prior art has following shortcoming at least:
The CP signal of time domain need to be preserved, and CP is additionally made DFT process, complexity is higher;
And the impact that the CP of time domain is subject to is more, and timing offset can cause the CP effective length to shorten, and the signal, particularly CP that comprises a plurality of users among the CP is not complete FFT symbol, can disturb so the CP signal transforms to the signal of frequency domain different user.Therefore adopt CP to estimate that the frequency deviation precision is relatively poor, even combination estimates that error probability is still larger with pilot reference signal.
Summary of the invention
In order to reduce the complexity of correcting frequency deviation, and reliable, the safe work of assurance system, the embodiment of the invention provides a kind of frequency correction method and apparatus.Described technical scheme is as follows:
A kind of correcting frequency deviation method comprises:
Receive current grouped data, obtain frequency domain data and the pilot data of user in current grouped data according to the described current grouped data that receives;
According to pilot data and described user the correcting frequency deviation result in the grouped data of overdeviation correction of described user in current grouped data, obtain the frequency offset estimation result of described user in current grouped data;
According to described frequency offset estimation result the frequency domain data of described user in current grouped data carried out correcting frequency deviation;
Wherein, the frequency offset estimation result of the described user of described acquisition in current grouped data specifically comprises:
Obtain the frequency deviation estimated value of described user in current grouped data according to the pilot data of described user in current grouped data;
According to the frequency deviation estimated value of described user in current grouped data, obtain the candidate frequency offset estimation result of described user in current grouped data;
According to the correcting frequency deviation result of described user in the grouped data of overdeviation correction, in described candidate's frequency offset estimation result, select the frequency offset estimation result of described user in current grouped data.
A kind of network equipment comprises:
Receiver module is used for receiving current grouped data, obtains frequency domain data and the pilot data of user in current grouped data according to the described current grouped data that receives;
Obtain module, be used for pilot data and the correcting frequency deviation result of described user in the grouped data of overdeviation correction in current grouped data according to described user, obtain the frequency offset estimation result of described user in current grouped data;
The correcting frequency deviation module is used for according to the frequency offset estimation result that described acquisition module obtains described user being carried out correcting frequency deviation at the frequency domain data of current grouped data;
Wherein, described acquisition module specifically comprises:
The frequency deviation estimated value obtains the unit, is used for obtaining the frequency deviation estimated value of described user in current grouped data according to described user at the pilot data of current grouped data;
Candidate's frequency offset estimation result obtains the unit, is used for according to the frequency deviation estimated value of described user in current grouped data, obtains the candidate frequency offset estimation result of described user in current grouped data;
Frequency offset estimation result obtains the unit, is used for the correcting frequency deviation result in the grouped data of overdeviation correction according to described user, selects the frequency offset estimation result of described user in current grouped data in described candidate's frequency offset estimation result.
The technical scheme that the embodiment of the invention provides by the correcting frequency deviation result of user in the grouped data that overdeviation is corrected in conjunction with the pilot data of user in current grouped data, obtain comparatively accurately frequency offset estimation result, and according to the correcting frequency deviation result who obtains the frequency domain data of user in current grouped data carried out correcting frequency deviation.The technical scheme computational complexity that provides of the embodiment of the invention is less, reliable, the effectively work of the system that can guarantee.
Description of drawings
Fig. 1 is the frequency correction method flow diagram that the embodiment of the invention one provides;
Fig. 2 is the signal schematic representation that receiving terminal that the embodiment of the invention one provides receives;
Fig. 3 is the frequency correction method flow diagram that the embodiment of the invention two provides;
Fig. 4 is the schematic diagram of the frequency deviation interval division that provides of the embodiment of the invention two;
Fig. 5 is the division schematic diagram in the subinterval in the frequency deviation interval that provides of the embodiment of the invention two;
Fig. 6 is the network equipment structural representation that the embodiment of the invention three provides;
Fig. 7 is the structural representation of the acquisition module that provides of the embodiment of the invention three;
Fig. 8 is the structural representation of candidate's frequency offset estimation result unit of providing of the embodiment of the invention three.
Embodiment
For making the purpose, technical solutions and advantages of the present invention clearer, embodiment of the present invention is described further in detail below in conjunction with accompanying drawing.
Embodiment one
Referring to Fig. 1, the embodiment of the invention provides a kind of correcting frequency deviation method, and the method mainly comprises:
101: receive current grouped data, obtain frequency domain data and the pilot data of user in current grouped data according to the current grouped data that receives;
Referring to Fig. 2, each grouping can be comprised of several OFDM symbols, and pilot data is distributed in the OFDM symbol of minority wherein, interval P OFDM symbol between nearest two OFDM symbols that include pilot data.
102: according to the pilot data of this user in current grouped data and the correcting frequency deviation result of this user grouped data of correcting in overdeviation, obtain the frequency offset estimation result of this user in current grouped data;
The grouped data of overdeviation correction can comprise: before receiving current grouped data, the any component group data that receive have been carried out respectively correcting frequency deviation according to the frequency offset estimation result of each user in this grouped data to each user in this grouped data.
The correcting frequency deviation result can comprise CRC (Cyclic Redundancy Check, CRC) feedback, also can be other results that can identify the data correctness behind the correcting frequency deviation.
103: according to frequency offset estimation result the frequency domain data of this user in current grouped data carried out correcting frequency deviation.
The embodiment of the invention by the correcting frequency deviation result of user in the grouped data that overdeviation is corrected in conjunction with the pilot data of user in current grouped data, obtain comparatively accurately frequency offset estimation result, and according to the correcting frequency deviation result who obtains the frequency domain data of user in current grouped data carried out correcting frequency deviation.The technical scheme computational complexity of the embodiment of the invention is less, reliable, the effectively work of the system that can guarantee.
Embodiment two
The embodiment of the invention provides a kind of correcting frequency deviation method, and take transmitting terminal as portable terminal, receiving terminal is example as the base station, referring to Fig. 3, the method comprises:
301: the base station mobile terminal receive is by the time domain data of the subcarrier transmission of a plurality of quadratures;
Here need to prove that the base station mobile terminal receive will be modulated at the highspeed serial data stream on the single carrier, be divided into the data flow of multi-path low speed, be modulated to the time domain data that walks abreast and send on the subcarrier of a plurality of quadratures.
The time domain data that each subcarrier that the base station receives sends sends with the unit of being grouped into.Each grouping can be comprised of several OFDM symbols, and pilot data is distributed in the OFDM symbol of minority wherein, interval P OFDM symbol between nearest two OFDM symbols that include pilot data;
Wherein, an OFDM symbol is comprised of CP and FFT sampling point.The length of CP is N Cp, the quantity of FFT sampling point is N FFT, the length=N of an OFDM symbol Cp+ N FFTWith time domain data with the benefit that the unit of being grouped into sends be: the data volume of each grouping is smaller, and compared with the whole OFDM symbols of continuous transmission, when correcting frequency deviation was carried out with the unit of being grouped in the base station, the data volume of processing can reduce largely; Simultaneously, correcting frequency deviation is carried out with the unit of being grouped in the base station, and the correcting frequency deviation result of each grouping can play to the correcting frequency deviation of next grouping prompting and help, has reduced the timing error that the whole OFDM symbols of continuous correction cause.
302: obtain frequency domain data and the pilot data of each user in current grouped data;
In this step, the base station receives the time domain data with the unit of being grouped into that portable terminal sends, abandon after CP in the time domain data of the current group that receives taken out, the FFT sampling point is carried out FFT conversion and user's separation, obtain each user's the frequency domain data in current grouped data and pilot data.
Need to prove, abandon after the CP in the time domain data of the current group that receives is taken out, can greatly reduce the computational complexity of whole frequency offset estimation procedure; Use the FFT sampling point to carry out FFT conversion user and separate, can suitably reduce the interference effect between the multi-user.
Present embodiment take m user at the frequency domain data of current group and pilot data as example.
Wherein, the frequency domain data in r the OFDM symbol on the frequency domain that the base station is received in k subcarrier is expressed as R (k, r);
If comprise pilot data in n the OFDM symbol on the frequency domain in k subcarrier, then this pilot data can be expressed as R RS(k, n), k=0 wherein, 1 ... K-1, wherein K is the sum of pilot data.
303: the pilot data to m user's current group carries out the estimation of channel impulse response coefficient, obtains the estimated value of channel impulse response coefficient;
The embodiment of the invention is with LS (Least Square, least square) estimated value that the method for estimating obtains the channel impulse response coefficient is example, in addition, the methods such as maximal possibility estimation, DFT transform domain channel estimating of can also using obtain the channel impulse response coefficient, the process that its process and LS estimate is basic identical, does not do at this and gives unnecessary details.
The estimated value H of the channel impulse response coefficient of pilot data in n the OFDM symbol in k subcarrier LS(k, n) can be expressed as:
H LS ( k , n ) = R RS ( k , n ) S RS * ( k , n ) | S RS ( k , n ) | 2 , k = 0,1 , . . . . . . K - 1
Wherein, S RS(k, n) refers to the pilot reference signal that does not impact through channel that portable terminal sends, for base station and portable terminal, S RS(k, n) is that both sides are known.S * RS(k, n) represents S RSThe conjugation of (k, n).
Because the pilot reference signal that portable terminal sends generally has | S RS(k, n) | 2=1, so following formula can be reduced to:
H LS ( k , n ) = R RS ( k , n ) S RS * ( k , n ) , k = 0,1 , . . . . . . K - 1
304: the frequency deviation estimated value of obtaining m user's current group according to the estimated value of the channel impulse response coefficient of adjacent two pilot datas recently in the current group;
Particularly, owing to differ (P-1) individual OFMD symbol between the sequence number of the sequence number of the OFDM symbol at a upper pilot data place and the OFDM symbol at this pilot data place, therefore, the LS estimated result when the channel impulse response coefficient of a upper pilot data is H LSWhen (k, n), the LS estimated result of the channel impulse response coefficient of adjacent nearest pilot data is H LS(k, n+P-1).Phase difference value between them is:
θ = angle { Σ k = 0 K - 1 H LS * ( k , n ) · H LS ( k , n + P - 1 ) }
Here need to prove, establish Γ = Σ k = 0 K - 1 H LS * ( k , n ) · H LS ( k , n + P - 1 ) , θ=angle{ Γ then } can specifically be expressed as θ=arctan (real part of imaginary part/Γ of Γ).
Secondly, according to phase difference value θ, calculate the decimal frequency bias estimated value of actual frequency deviation value of m user's current group, here need to prove, in the present embodiment take the decimal frequency bias estimated value as example, the method of other calculating frequency deviation estimated values and the method for decimal frequency bias estimated value are substantially similar, do not do detailed description at this.
Particularly, the decimal frequency bias estimated value can be calculated according to following formula:
ϵ ^ RS = θ · N FFT 2 π · P · ( N FFT + N CP )
Here need to prove, in a grouping, P-1 the OFDM symbol of being separated by between adjacent two nearest pilot datas, the interval is larger, and the frequency deviation region that causes pilot tone to be estimated is less, is not enough to cover actual frequency deviation region.Therefore, need to estimate that resulting frequency deviation estimated value does the actual frequency deviation value that further processing just can obtain m user's current group to pilot tone.
305: the frequency deviation estimated value of m the user's who estimates according to pilot tone current group, candidate's frequency offset estimation result of m user's current group in the actual frequency deviation region of acquisition in the frequency deviation interval;
In this step, use the frequency offset estimation range of pilot tone estimation as the size in a frequency deviation interval, user's actual frequency deviation region is divided into a plurality of frequency deviations interval, and according to the decimal frequency bias estimated value position in the frequency deviation interval under it that calculates in 304, obtain candidate's frequency offset estimation result of m identical with the position at decimal frequency bias estimated value place in frequency deviation interval user current group.
Particularly, the division in frequency deviation interval can comprise:
1) base station is calculated the actual frequency deviation region that this up-link may reach according to the carrier frequency F of up-link and portable terminal with respect to the translational speed V of base station, wherein, frequency deviation is proportional to system carrier frequency F and portable terminal with respect to the translational speed V of base station.
Particularly, the actual frequency deviation maximum frequency deviation scope that can reach is
Figure GSB00000711347100071
Wherein, C represents the light velocity; So, this up-link may reach actual maximum frequency deviation scope and can be expressed as
Figure GSB00000711347100072
2) calculate the frequency deviation region that pilot tone is estimated;
Because this up-link is known, the frequency deviation region that pilot tone is estimated between portable terminal and the base station so is known.If the frequency deviation region that pilot tone is estimated is
Figure GSB00000711347100073
So
Figure GSB00000711347100074
N wherein RSBe two and comprise the time domain sampling point number of being separated by between the OFMD symbol of pilot data, Δ f is the frequency interval between the subcarrier.
Accordingly, the frequency offset estimation range of pilot tone estimation is
3) frequency offset estimation range that utilizes pilot tone to estimate
Figure GSB00000711347100076
The actual frequency deviation region ε that this up-link may be reached MaxIt is interval to be divided into a plurality of frequency deviations;
Concrete division methods can comprise:
According to ε Zone, with ε MaxIt is interval to be divided into U frequency deviation, is that zero position is the central point in first frequency deviation interval from frequency deviation, be negative to frequency deviation respectively, and frequency deviation is that positive both direction carries out the division in frequency deviation interval.Frequency deviation interval after the division is respectively with 1,2 ..., U identifies.Wherein, because this dividing mode in frequency deviation interval, so that all the frequency deviation interval is interval symmetrical about first frequency deviation, so the value of U is odd number.The value of U can be passed through will
Figure GSB00000711347100081
Value round up and calculate, when the calculated value of U was even number, actual U value need to add 1.
For example, suppose that U is 3, so interval division can be as shown in Figure 4, and the scope in first frequency deviation interval is
Figure GSB00000711347100082
Second frequency deviation interval is positioned at the negative sense in first frequency deviation interval, and scope is
Figure GSB00000711347100083
The 3rd frequency deviation interval is positioned at the forward in first frequency deviation interval, and scope is ( ϵ zone 2 , ϵ max 2 ] .
For example, the actual frequency deviation region of supposing the user is [10,10], and the frequency offset estimation range that pilot tone is estimated is [3,3], the frequency offset estimation range that uses pilot tone to estimate carries out the division in frequency deviation interval with user's actual frequency deviation region, and the frequency deviation interval after the division can be expressed as [10 ,-9], [9,-3], [3,3], [3,9], [9,10].The decimal frequency bias value of supposing m the user's that pilot tone is estimated current group is 1, drop on [3,3] within this frequency deviation interval, according to 1 position in current frequency deviation interval, than the left end point in frequency deviation interval large 4, less by 2 than the right endpoint in frequency deviation interval, in whole frequency deviation intervals, obtain the frequency deviation estimated value of m user's current group in the actual frequency deviation region, that is: there is not such frequency deviation estimated value in [10 ,-9], [9,10] these two frequency deviation intervals, [9,-3] the frequency deviation estimated value in the frequency deviation interval is-5, and the frequency deviation estimated value in [3,9] frequency deviation interval is 7.
306: the correcting frequency deviation result of the grouped data of correcting according to overdeviation, candidate's frequency offset estimation result in which frequency deviation interval of choice for use is as frequency offset estimation result;
Wherein, the correcting frequency deviation result of the grouped data of overdeviation correction can feed back for CRC, and the CRC feedback specifically refers to: the correcting frequency deviation result of the grouped data of overdeviation correction carries out CRC through demodulation and after deciphering, and obtains CRC and feeds back.
If the correcting frequency deviation result's of the grouped data of overdeviation correction CRC is fed back to mistake, illustrate that the frequency offset estimation result that grouped data that overdeviation is corrected adopts is not m user's actual frequency deviation value, the frequency deviation interval at the actual frequency deviation value place that the frequency deviation interval under the frequency offset estimation result that adopts of the overdeviation grouped data of correcting neither m user, so use candidate's frequency offset estimation result in the different frequency deviations of the frequency offset estimation result interval of adopting from the grouped data of overdeviation correction as the frequency offset estimation result of current grouped data, continue that grouped data is carried out frequency deviation and estimate; Here need to prove, the interval different frequency deviation interval of frequency deviation at the frequency offset estimation result place of the grouped data sampling of correcting from overdeviation can have a plurality of, during selection, can select at random different frequency deviations interval, also can be to select one by one in a certain order.
If the correcting frequency deviation result's of the grouped data of overdeviation correction CRC is fed back to correctly, illustrate that the frequency offset estimation result that grouped data that overdeviation is corrected adopts is m user's actual frequency deviation value, accordingly, frequency deviation interval, frequency offset estimation result place also is that the frequency deviation under the actual frequency deviation value is interval, therefore the frequency deviation under the frequency offset estimation result that the grouped data that continues to use overdeviation to correct adopts is interval, uses candidate's frequency offset estimation result in the identical frequency deviation of frequency offset estimation result interval of the grouped data employing of correcting with overdeviation as the frequency offset estimation result of current grouped data.
Need to prove: after CRC was fed back to correctly, the base station can require portable terminal that original grouped data is retransmitted, in order to actual frequency deviation value whole grouped datas are carried out correcting frequency deviation.
Here also need to prove, when the first component group data are carried out correcting frequency deviation, owing to there not be the correcting frequency deviation result's of the grouped data that overdeviation corrects CRC to feed back, at this moment can be set to a most possible value by frequency deviation value, perhaps be initialized as zero, namely hypothesis does not have frequency deviation.
307: according to the frequency deviation value of m user's current group the frequency domain data of m user's current group is carried out correcting frequency deviation;
308: the data that will carry out behind the correcting frequency deviation are carried out demodulation and decoding, and the data after demodulation and the decoding are selected frequency offset estimation result as the correcting frequency deviation result for other grouped datas in candidate's frequency offset estimation result reference is provided.
Here, the correcting frequency deviation result can feed back for CRC, and the data after soon demodulation and the decoding are carried out CRC, obtains the CRC feedback.
Further, when guaranteeing frequency deviation estimated value generation saltus step, do not affect the correctness of actual frequency deviation value, can do further each frequency deviation interval and divide:
A) each frequency deviation interval is divided into further subinterval, border and subinterval, non-border.
Certainly, subinterval, non-border also can be divided between a plurality of non-border cells, and the frequency range of each minizone is not less than the jitter range of frequency deviation.Here, jitter range refers to the minimum value that frequency deviation changes.
Referring to Fig. 5, suppose U=3, each frequency deviation interval can be divided into respectively A, B, three subintervals of C, wherein subinterval A belongs to subinterval, non-border, and subinterval B, C all belong to the subinterval, border.
Need to prove that strict regulation is not done in the division in subinterval, trisection can be carried out in the interval, also can subinterval, non-border shared ratio in whole interval be higher than the shared ratio in subinterval, border.Certainly, can also further divide subinterval, non-border, being about to the frequency deviation interval division is 4,5 ... the subinterval, comprising subinterval, 2 borders and subinterval, a plurality of non-border.
B) judge the decimal frequency bias estimated value
Figure GSB00000711347100101
Drop on the subinterval in which ready-portioned frequency deviation interval;
As shown in Figure 5, suppose to estimate Be positioned at the X1 position in the A1 subinterval in the first frequency deviation interval, corresponding, in the X2 position in the A2 subinterval in the second frequency deviation interval, the X3 position in the A3 subinterval in the 3rd frequency deviation interval, all be candidate's frequency offset estimation result of m user's current group.
Concrete, referring to Fig. 5, suppose that it is subinterval A2 in frequency deviation interval 2 that actual frequency deviation value begins, through after several groupings, actual frequency deviation value may change to certain position of C2, because C2 still belongs to frequency deviation interval 2, therefore this value still can be used as actual frequency deviation value, if but actual frequency deviation continues to change to B3, so because the decimal frequency bias estimated value of calculating can be B1, B2, among the B3 one, if but at this moment locking thinks that still actual frequency deviation value is positioned at frequency deviation interval 2, so just and actual frequency deviation value deviation has been arranged, so need to follow the tracks of the frequency deviation interval, can be reached for the effect that later frequency deviation estimates to provide reference value.Specific practice is as follows:
C) follow the tracks of the actual frequency deviation value of each grouping, when actual frequency deviation value changes to another subinterval, border from subinterval, a border, it is interval the frequency deviation interval need to be changed to the frequency deviation adjacent with changing subinterval, border before, thereby finish interval change, effectively prevented the shake in frequency deviation interval.
Certainly, if after having determined the frequency deviation interval, continuous mistake has appearred in CRC, then needs to re-start the search in frequency deviation interval, until the CRC feedback is correct.
Concrete, suppose that from the A1 subinterval the 1st grouping adopted
Figure GSB00000711347100103
(A1) as frequency offset estimation result, wherein
Figure GSB00000711347100104
(A1) be the frequency deviation estimated value in A1 subinterval, after demodulation and decoding, obtain the CRC feedback, if the CRC that receives is fed back to mistake, then the 2nd grouping can be adopted
Figure GSB00000711347100105
(A2) as the frequency offset estimation result in A2 subinterval, by that analogy, until the CRC that receives is fed back to correctly.Certainly, also can only adopt a grouping to carry out auto frequency deviation corrects, in a certain order namely, with the candidate's frequency offset estimation result in the different frequency deviation intervals frequency domain data of m user in the same grouping is carried out correcting frequency deviation, until the CRC that receives is fed back to correctly.
Need to prove that the method that the embodiment of the invention provides can be used for the system beyond the OFDM, as long as the frequency offset estimation range of reference signal is less, and actual frequency deviation can be carried out correcting frequency deviation by the method larger the time.Only need to take frequency deviation cycle that reference signal is estimated as interval, actual frequency deviation is divided into several intervals, then carry out interval search and interval the tracking on the basis of feedback CRC, thereby locking frequency deviation interval and then obtains comparatively accurately frequency deviation estimated value.
It is interval that the embodiment of the invention is divided into several frequency deviations by the actual frequency deviation region that the user may be reached, carrying out frequency deviation in conjunction with the pilot data of user in current grouped data estimates, by the correcting frequency deviation result of user in the grouped data of overdeviation correction, obtain user's frequency offset estimation result comparatively accurately in current group, thereby reach the user is carried out the effect that effective frequency deviation is corrected in current grouped data.And, by effective interval division technology, guarantee the reliability and stability of frequency-tracking, can the generating region jitter.The technical scheme computational complexity of the embodiment of the invention is less, and is subjected to the impact of timing error, multi-user interference less, reliable, the effectively work of the system that can guarantee.
Embodiment three
Referring to Fig. 6, the embodiment of the invention provides a kind of network equipment, comprising:
Receiver module 601 is used for receiving current grouped data, obtains frequency domain data and the pilot data of user in current grouped data according to the current grouped data that receives;
Obtain module 602, be used for pilot data and the correcting frequency deviation result of user in the grouped data of overdeviation correction in current grouped data according to the user, obtain the frequency offset estimation result of user in current grouped data;
Correcting frequency deviation module 603 is used for according to the frequency offset estimation result that obtains module 602 acquisitions the user being carried out correcting frequency deviation at the frequency domain data of current grouped data.
Here need to prove, when whole grouped datas are not all carried out correcting frequency deviation, obtain module 602 and also be used for: it is zero at current grouped data frequency deviation estimated result that the user is set.
Wherein, with reference to the corresponding description of previous methods embodiment, referring to Fig. 7, obtaining module 602 can comprise:
The frequency deviation estimated value obtains unit 602A, is used for obtaining the frequency deviation estimated value of user in current grouped data according to the user at the pilot data of current grouped data;
Candidate's frequency offset estimation result obtains unit 602B, is used for according to the frequency deviation estimated value of user in current grouped data, obtains the candidate frequency offset estimation result of user in current grouped data;
Frequency offset estimation result obtains unit 602C, is used for the correcting frequency deviation result in the grouped data of overdeviation correction according to the user, selects the frequency offset estimation result of user in current grouped data in candidate's frequency offset estimation result.
Concrete, with reference to the corresponding description of previous methods embodiment, the frequency deviation estimated value obtains unit 602A and can comprise:
Coefficient estimator unit is for the channel impulse response coefficient estimated value of obtaining pilot data;
Obtain subelement, obtain the frequency deviation estimated value of user's current group for the channel impulse response coefficient estimated value of two the adjacent nearest pilot signals that obtain according to coefficient estimator unit.
Concrete, with reference to the corresponding description of previous methods embodiment, referring to Fig. 8, candidate's frequency offset estimation result unit 602B can comprise:
Frequency deviation interval division subelement 602B1, it is interval that the actual frequency deviation region that is used for user that will precognition is divided into a plurality of frequency deviations;
Obtain subelement 602B2, be used for according to frequency deviation estimated value it under position frequency deviation interval in of user in current grouped data, in a plurality of frequency deviations interval, obtain a plurality of candidate frequency offset estimation result identical with the position.
Wherein, with reference to the corresponding description of previous methods embodiment, frequency deviation interval division subelement 602B1 is used for:
The frequency offset estimation range that pilot tone is estimated is as the size in a frequency deviation interval, take the mid point of the position of frequency deviation as zero as first frequency deviation interval, interval for negative both direction is divided into a plurality of frequency deviations with the user's of precognition actual frequency deviation region for just reaching frequency deviation to frequency deviation respectively.
Need to prove, when the correcting frequency deviation result of user in the grouped data of overdeviation correction is: when the CRC CRC the user carries out correcting frequency deviation in the grouped data that overdeviation is corrected after fed back, frequency offset estimation result obtained unit 602C and is used for:
If the CRC of user behind the correcting frequency deviation of the grouped data of overdeviation correction is fed back to mistake, select to belong to candidate's frequency offset estimation result in different frequency deviations interval as the frequency offset estimation result of current group from the user in the frequency offset estimation result of the grouped data of overdeviation correction in candidate's frequency offset estimation result of user in current grouped data;
If the CRC of user behind the correcting frequency deviation of the grouped data of overdeviation correction is fed back to correctly, select to belong to candidate's frequency offset estimation result in identical frequency deviation interval as the frequency offset estimation result of current group with the user in the frequency offset estimation result of the grouped data of overdeviation correction in candidate's frequency offset estimation result of user in current grouped data.
Further, with reference to the corresponding description of previous methods embodiment, candidate's frequency offset estimation result unit 602B can also comprise:
Subelement is divided in the subinterval, is subinterval, border and subinterval, non-border with each frequency deviation interval division;
Then obtain subelement 602B2 also use can in:
When changing to another subinterval, border from subinterval, a border in the frequency deviation interval of frequency deviation estimated value under it, use with change before adjacent frequency deviation interval, subinterval, border in the frequency deviation estimated value as the frequency deviation value of current group.
Need to prove that the network equipment in the present embodiment is specifically as follows the base station.
The network equipment that the embodiment of the invention provides, by the correcting frequency deviation result of user in the grouped data that overdeviation is corrected in conjunction with the pilot data of user in current grouped data, obtain comparatively accurately frequency offset estimation result, and according to the correcting frequency deviation result who obtains the frequency domain data of user in current grouped data carried out correcting frequency deviation.Further, it is interval that the embodiment of the invention is divided into several frequency deviations by the actual frequency deviation region that the user may be reached, and guarantees the reliability and stability of frequency-tracking, can the generating region jitter.The technical scheme computational complexity of the embodiment of the invention is less, and is subjected to the impact of timing error, multi-user interference less, reliable, the effectively work of the system that can guarantee.
The embodiment of the invention can utilize software to realize, corresponding software program can be stored in the storage medium that can read, for example, and in the hard disk of router, buffer memory or the CD.
The above only is preferred embodiment of the present invention, and is in order to limit the present invention, within the spirit and principles in the present invention not all, any modification of doing, is equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (12)

1. a correcting frequency deviation method is characterized in that, comprising:
Receive current grouped data, obtain frequency domain data and the pilot data of user in current grouped data according to the described current grouped data that receives;
According to pilot data and described user the correcting frequency deviation result in the grouped data of overdeviation correction of described user in current grouped data, obtain the frequency offset estimation result of described user in current grouped data;
According to described frequency offset estimation result the frequency domain data of described user in current grouped data carried out correcting frequency deviation;
Wherein, the frequency offset estimation result of the described user of described acquisition in current grouped data specifically comprises:
Obtain the frequency deviation estimated value of described user in current grouped data according to the pilot data of described user in current grouped data;
According to the frequency deviation estimated value of described user in current grouped data, obtain the candidate frequency offset estimation result of described user in current grouped data;
According to the correcting frequency deviation result of described user in the grouped data of overdeviation correction, in described candidate's frequency offset estimation result, select the frequency offset estimation result of described user in current grouped data.
2. correcting frequency deviation method as claimed in claim 1 is characterized in that, when whole grouped datas were not all carried out correcting frequency deviation, it was zero at current grouped data frequency deviation estimated result that described user is set.
3. correcting frequency deviation method as claimed in claim 1 is characterized in that, describedly obtains the frequency deviation estimated value of described user in current grouped data according to the pilot data of described user in current grouped data, comprising:
Obtain the channel impulse response coefficient estimated value of described pilot data;
Obtain the frequency deviation estimated value of described user's current group according to the channel impulse response coefficient estimated value of adjacent two pilot signals recently.
4. correcting frequency deviation method as claimed in claim 1 is characterized in that, and is described according to the frequency deviation estimated value of described user in current grouped data, obtains the candidate frequency offset estimation result of described user in current grouped data, comprising:
It is interval that described user's the actual frequency deviation region of precognition is divided into a plurality of frequency deviations, according to the frequency deviation estimated value of described user in current grouped data position in the frequency deviation interval under it, in described a plurality of frequency deviations interval, obtain the identical candidate's frequency offset estimation result in a plurality of and described position.
5. correcting frequency deviation method as claimed in claim 4, it is characterized in that the correcting frequency deviation result of described user in the grouped data of overdeviation correction is: the CRC CRC feedback described user carries out correcting frequency deviation in the grouped data that overdeviation is corrected after;
Then described according to the correcting frequency deviation result of described user in the grouped data of overdeviation correction, in described candidate's frequency offset estimation result, select the frequency offset estimation result of current group, comprising:
If the CRC of described user behind the correcting frequency deviation of the grouped data of overdeviation correction is fed back to mistake, select to belong to candidate's frequency offset estimation result in different frequency deviations interval as the frequency offset estimation result of current group from described user in the frequency offset estimation result of the grouped data of overdeviation correction in candidate's frequency offset estimation result of described user in current grouped data;
If the CRC of described user behind the correcting frequency deviation of the grouped data of overdeviation correction is fed back to correctly, select to belong to candidate's frequency offset estimation result in identical frequency deviation interval as the frequency offset estimation result of current group with described user in the frequency offset estimation result of the grouped data of overdeviation correction in candidate's frequency offset estimation result of described user in current grouped data.
6. correcting frequency deviation method as claimed in claim 4 is characterized in that, described method also comprises:
Be subinterval, border and subinterval, non-border with each described frequency deviation interval division;
Then when changing to another subinterval, border from subinterval, a border in the frequency deviation interval of described frequency deviation estimated value under it, use with change before adjacent frequency deviation interval, subinterval, border in the frequency deviation estimated value as the frequency deviation value of current group.
7. a network equipment is characterized in that, described equipment comprises:
Receiver module is used for receiving current grouped data, obtains frequency domain data and the pilot data of user in current grouped data according to the described current grouped data that receives;
Obtain module, be used for pilot data and the correcting frequency deviation result of described user in the grouped data of overdeviation correction in current grouped data according to described user, obtain the frequency offset estimation result of described user in current grouped data;
The correcting frequency deviation module is used for according to the frequency offset estimation result that described acquisition module obtains described user being carried out correcting frequency deviation at the frequency domain data of current grouped data;
Wherein, described acquisition module specifically comprises:
The frequency deviation estimated value obtains the unit, is used for obtaining the frequency deviation estimated value of described user in current grouped data according to described user at the pilot data of current grouped data;
Candidate's frequency offset estimation result obtains the unit, is used for according to the frequency deviation estimated value of described user in current grouped data, obtains the candidate frequency offset estimation result of described user in current grouped data;
Frequency offset estimation result obtains the unit, is used for the correcting frequency deviation result in the grouped data of overdeviation correction according to described user, selects the frequency offset estimation result of described user in current grouped data in described candidate's frequency offset estimation result.
8. network equipment as claimed in claim 7 is characterized in that, when whole grouped datas were not all carried out correcting frequency deviation, described acquisition module also was used for: it is zero at current grouped data frequency deviation estimated result that described user is set.
9. network equipment as claimed in claim 7 is characterized in that, described frequency deviation estimated value obtains the unit and comprises:
Coefficient estimator unit is for the channel impulse response coefficient estimated value of obtaining described pilot data;
Obtain subelement, obtain the frequency deviation estimated value of described user's current group for the channel impulse response coefficient estimated value of two the adjacent nearest pilot signals that obtain according to described coefficient estimator unit.
10. network equipment as claimed in claim 7 is characterized in that, described candidate's frequency offset estimation result obtains the unit and comprises:
Frequency deviation interval division subelement, the actual frequency deviation region that is used for the described user that will predict is divided into a plurality of frequency deviations interval;
Obtain subelement, be used for according to frequency deviation estimated value it under position frequency deviation interval in of described user in current grouped data, in described a plurality of frequency deviations interval, obtain the identical candidate's frequency offset estimation result in a plurality of and described position.
11. network equipment as claimed in claim 7, it is characterized in that the correcting frequency deviation result of described user in the grouped data of overdeviation correction is: the CRC CRC feedback described user carries out correcting frequency deviation in the grouped data that overdeviation is corrected after;
Then described frequency offset estimation result obtains the unit and is used for:
If the CRC of described user behind the correcting frequency deviation of the grouped data of overdeviation correction is fed back to mistake, select to belong to candidate's frequency offset estimation result in different frequency deviations interval as the frequency offset estimation result of current group from described user in the frequency offset estimation result of the grouped data of overdeviation correction in candidate's frequency offset estimation result of described user in current grouped data;
If the CRC of described user behind the correcting frequency deviation of the grouped data of overdeviation correction is fed back to correctly, select to belong to candidate's frequency offset estimation result in identical frequency deviation interval as the frequency offset estimation result of current group with described user in the frequency offset estimation result of the grouped data of overdeviation correction in candidate's frequency offset estimation result of described user in current grouped data.
12. network equipment as claimed in claim 10 is characterized in that, described candidate's frequency offset estimation result obtains the unit and also comprises:
Subelement is divided in the subinterval, is subinterval, border and subinterval, non-border with each described frequency deviation interval division;
Then described acquisition subelement also is used for:
When changing to another subinterval, border from subinterval, a border in the frequency deviation interval of described frequency deviation estimated value under it, use with change before adjacent frequency deviation interval, subinterval, border in the frequency deviation estimated value as the frequency deviation value of current group.
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