CN1980208A - Carrier-wave frequency deviation estimation method in communication system, apparatus and system therefor - Google Patents
Carrier-wave frequency deviation estimation method in communication system, apparatus and system therefor Download PDFInfo
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- CN1980208A CN1980208A CN 200510127403 CN200510127403A CN1980208A CN 1980208 A CN1980208 A CN 1980208A CN 200510127403 CN200510127403 CN 200510127403 CN 200510127403 A CN200510127403 A CN 200510127403A CN 1980208 A CN1980208 A CN 1980208A
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Abstract
The method includes following procedures: receiving synchronizing pilot sequence, and obtaining oversampling in frequency domain for synchronizing pilot sequence; on discrete frequency spectrum of oversampling in frequency domain in synchronizing pilot sequence, calculating square of amplitudes of discrete frequency spectrum lines, and summarizing them in order to obtain measure sequence; based on measure sequence to carry out estimation for carrier frequency shift. The invention increases precision of estimating carrier frequency shift, and range of estimation remarkably without increasing complexity.
Description
Technical field
The present invention relates to communication technical field, more specifically, particularly carrier frequency deviation estimating method and device and system in the communication system.
Background technology
Current, whole world digital mobile communication system (GSM) and CDMA mobile communication systems (CDMA) have all obtained using very widely in worldwide, and WCDMA mobile communication system (WCDMA) and WCDMA mobile communication system 2000 mobile communication system such as (CDMA2000) have also obtained application to a certain degree within the specific limits.OFDM (OFDM) technology has the ability of antagonism intersymbol interference (ISI), can provide very high spectrum efficiency simultaneously, therefore is regarded as one of most possible transmission technology that adopts of mobile radio system of future generation.The OFDM technology has obtained extensive use at numerous areas such as Digital Subscriber Loop, digital audio/video broadcasting, WLAN (wireless local area network) and wireless MANs.
Simultaneous techniques is one of key technology in the communication system, and the Carrier frequency offset estimation technology is requisite a kind of in the communication system simultaneous techniques.Such as, for ofdm system, carrier frequency shift can be introduced inter-carrier interference (ICI), causes the effective SNR of system to descend, and makes system performance degradation.For SNR is descended less than 0.1dB, maximum frequency deviation should be less than 1% of subcarrier spacing.In ofdm system, generally adopt track loop to carry out frequency offset detection, and estimate frequency offseting value, and then carry out frequency compensation.Projection method for frequency deviation mainly comprises according to synchronization blocks special-purpose in the OFDM frame (Frame) to be analyzed, analyzes, utilizes the characteristic of OFDM symbol or frequency spectrum to analyze etc. according to the signal of fast Fourier transform (FFT) output.
A kind of frequency offset estimation methods based on the single-frequency pilot frequency sequence is arranged at present.In this method, can cause the frequency spectrum shift of pilot frequency sequence according to carrier frequency shift, design has the pilot frequency sequence of pectination frequency spectrum, thereby can estimate the frequency domain skew.Fig. 1 is based on the spectrogram of the synchronizing signal of single-frequency pilot frequency sequence in the prior art.As shown in Figure 1, pilot frequency sequence has the pectination frequency spectrum, thereby can estimate the frequency domain skew.
In this frequency offset estimation methods based on the single-frequency pilot frequency sequence, maximum can detected Frequency offset estimation be at interval 0.5 times of pectination frequency.But if carrier frequency shift surpasses this scope, then this method can not accurately detect frequency shift (FS).The precision of this frequency offset estimation methods only is a subcarrier spacing.For multicarrier system, this can introduce ICI, and it is desired than the low error rate index to satisfy communication system.
Summary of the invention
In view of this, main purpose of the present invention is the method that proposes Carrier frequency offset estimation in a kind of communication system, to improve the scope of Carrier frequency offset estimation.
Another object of the present invention is to propose Carrier frequency offset estimation device in a kind of communication system, to improve the scope of Carrier frequency offset estimation.
Another object of the present invention is to propose Carrier frequency offset estimation system in a kind of communication system, to improve the scope of Carrier frequency offset estimation.
For achieving the above object, technical scheme of the present invention is achieved in that
Carrier frequency deviation estimating method in a kind of communication system, this method may further comprise the steps:
A, receive the synchronizing pilot sequence, and obtain the frequency domain over-sampling of described synchronizing pilot sequence;
B, on the discrete spectrum of the frequency domain over-sampling of described synchronizing pilot sequence, calculate several discrete spectral lines amplitude square, and it is sued for peace, to obtain estimating sequence;
C, estimate sequence and carry out Carrier frequency offset estimation according to described.
The described frequency domain over-sampling that obtains of steps A comprises:
A1, synchronizing pilot sequence execution time domain zero padding to receiving;
A2, the synchronizing pilot sequence after the time domain zero padding is carried out Fourier change, to obtain the frequency domain over-sampling of synchronizing pilot sequence.
Described synchronizing pilot sequence comprises at least two sub-synchronizing pilot sequences, and described sub-synchronizing pilot sequence comprises arrowband composition and broadband composition, and the amplitude of the discrete spectral line of arrowband composition correspondence is higher than the amplitude of the discrete spectral line of broadband composition correspondence.
Described each sub-synchronizing pilot sequence is identical.
Frequency interval between the centre frequency of described sub-synchronizing pilot sequence arrowband composition is greater than the coherence bandwidth of channel.
Frequency interval between the centre frequency of described sub-synchronizing pilot sequence arrowband composition is a unequal interval.
The spectral line that described sub-synchronizing pilot sequence arrowband becomes branch to show is a single-frequency pilot tone spectral line.
The spectral line that described sub-synchronizing pilot sequence broadband becomes branch to show further comprises: described spectral line is the smooth discrete spectral line of amplitude.
The spectral line that described sub-synchronizing pilot sequence broadband becomes branch to show further comprises: described spectral line such as is at an amplitude.
The spectral line that described sub-synchronizing pilot sequence broadband becomes branch to show further comprises: near the described spectral line frequency domain arrowband composition is the discrete spectral line of 0 amplitude.
The frequency domain interval of several single-frequency pilot frequency sequences in the frequency interval between described several the discrete spectral lines of step B and the described synchronizing pilot sequence is identical.
Described step C comprises:
C1, estimate the skew that sequencal estimation goes out the frequency sampling point according to described;
C2, estimate described carrier frequency shift according to the skew of described frequency sampling point.
Described communication system is OFDM (OFDM) communication system.
Carrier frequency offset estimation device in a kind of communication system, this device comprises:
Frequency domain over-sampling acquiring unit is used to obtain the frequency domain over-sampling of the synchronizing pilot sequence that receives;
Estimate sequence calculation sequence, be used for discrete spectrum at the frequency domain over-sampling of described synchronizing pilot sequence, calculate several discrete spectral lines amplitude square, and it is sued for peace, to obtain estimating sequence;
The Carrier frequency offset estimation unit is used for estimating sequence and carrying out Carrier frequency offset estimation according to described;
Its frequency domain over-sampling acquiring unit with estimate sequence calculation sequence and be connected, estimate sequence calculation sequence and be connected with the Carrier frequency offset estimation unit.
Described frequency domain over-sampling acquiring unit comprises:
Time domain zero padding unit is used for the synchronizing pilot sequence that receives is carried out the time domain zero padding;
Fourier transformation unit is used for the synchronizing pilot sequence after the zero padding is carried out Fourier transform;
Wherein time domain zero padding unit is connected with Fourier transformation unit.
Described Carrier frequency offset estimation unit comprises:
Maximum detection unit determines to estimate the peaked sequence number of sequence;
The reference value unit is used to preserve predefined reference number;
The Frequency offset estimation computing unit is used for estimating the peaked sequence number of sequence and predefined reference number and carrying out subtraction described, obtaining the skew of frequency sampling point, and according to the calculations of offset Carrier frequency offset estimation of described frequency sampling point;
Wherein maximum detection unit is connected with the Frequency offset estimation computing unit, and the reference value unit is connected with the Frequency offset estimation computing unit.
Described Fourier transformation unit is FFT unit or DFT unit.
Described communication system is an ofdm communication system.
Clock synchronization system in a kind of communication system, this system comprises:
Thick time synchronism apparatus is used for to received signal sequence and carries out initial time and estimate synchronously, and estimates synchronously that according to described initial time sequence is carried out initial time delay adjustment to received signal;
As above each described Carrier frequency offset estimation device is used for the received signal sequence through initial time delay adjustment is carried out Carrier frequency offset estimation;
The carrier frequency shift compensation arrangement, be used for according to described Carrier frequency offset estimation to received signal sequence carry out carrier frequency shift compensation;
The exact time synchronization device is used for estimating carrying out exact time synchronization through the received signal sequence of carrier frequency shift compensation, and estimates this received signal sequence is carried out the precise delay adjustment according to described exact time synchronization;
Wherein thick time synchronism apparatus is connected with the Carrier frequency offset estimation device, and the Carrier frequency offset estimation device is connected with the carrier frequency shift compensation arrangement, and the carrier frequency shift compensation arrangement is connected with the exact time synchronization device with thick time synchronism apparatus.
As can be seen from the above technical solutions, in the present invention, may further comprise the steps: the synchronizing pilot sequence that receives is carried out the time domain zero padding, and the synchronizing pilot sequence after the zero padding is carried out Fourier transform, to obtain the frequency domain over-sampling of synchronizing pilot sequence; On the frequency spectrum of the frequency domain over-sampling of synchronizing pilot sequence, the power spectrum amplitude sum that has same frequency subcarrier sequence at interval according to the interval calculation of single-frequency pilot signal, to obtain estimating sequence, wherein the interval of the sub-carrier signal that is calculated is corresponding with the interval between the pilot frequency sequence; Estimate sequence and carry out Carrier frequency offset estimation according to described.This shows, in the present invention, by carrying out the time domain zero padding, it is the frequency domain over-sampling, the precision of Frequency offset estimation is relevant with frequency oversample factor P, so the present invention can accurately estimate the frequency shift (FS) less than the OFDM subcarrier spacing, thereby can improve the scope of Carrier frequency offset estimation.
In addition, at receiving terminal, use the present invention after, can also be further the power spectrum amplitude of multistage synchronizing pilot sequence be averaged, obtaining high SNR, and overcome the influence of channel fading to Frequency offset estimation.
Description of drawings
Fig. 1 is based on the spectrogram of the synchronizing signal of the Frequency offset estimation of single-frequency pilot frequency sequence in the prior art.
Fig. 2 is according to exemplary frequency deviation estimating method schematic flow sheet of the present invention.
Fig. 3 is according to exemplary synchronization pilot symbol structure schematic diagram of the present invention.
Fig. 4 is the spectrum amplitude schematic diagram according to exemplary synchronization pilot frequency sequence of the present invention.
Fig. 5 is the spectrum amplitude schematic diagram according to exemplary synchronization pilot frequency sequence of the present invention.
Fig. 6 is the spectrum amplitude schematic diagram according to exemplary synchronization pilot frequency sequence of the present invention.
Fig. 7 is the spectrum amplitude schematic diagram according to exemplary synchronization pilot frequency sequence of the present invention.
Fig. 8 is the spectrum amplitude schematic diagram of synchronizing pilot sequence according to an embodiment of the invention.
Fig. 9 is for estimating the amplitude schematic diagram of sequence according to an embodiment of the invention.
Figure 10 is according to exemplary frequency skew estimation unit structural representation of the present invention.
Figure 11 is Frequency offset estimation apparatus structure schematic diagram according to an embodiment of the invention.
Figure 12 is the clock synchronization system in the communication system according to an embodiment of the invention.
Embodiment
For making the purpose, technical solutions and advantages of the present invention express clearlyer, the present invention is further described in more detail below in conjunction with drawings and the specific embodiments.
Main thought of the present invention is: at first at receiving terminal the synchronizing pilot sequence that receives is carried out the time domain zero padding, and the synchronizing pilot sequence after the zero padding is carried out Fourier transform, to obtain the frequency domain over-sampling of synchronizing pilot sequence; Then on the frequency spectrum of the frequency domain over-sampling of synchronizing pilot sequence, the power spectrum amplitude sum that has same frequency subcarrier sequence at interval according to the interval calculation of single-frequency pilot signal, to obtain estimating sequence, wherein the interval of the sub-carrier signal that is calculated is corresponding with the interval between the pilot frequency sequence; Last basis is estimated sequence and is carried out Carrier frequency offset estimation.
Synchronizing pilot sequence of the present invention, preferably form by two or more sub-synchronizing pilot sequences, each sub-synchronizing pilot sequence comprises two parts, wherein, a part is several arrowband compositions, and the spectral line that the arrowband becomes branch to show is: some successive lines that have higher magnitude on the discrete spectrum; A part is several broadband compositions, and the spectral line that the broadband becomes branch to show is: have some successive lines than low amplitude value on the discrete spectrum.Described each sub-synchronizing pilot sequence is identical.And, frequency interval between the centre frequency of sub-synchronizing pilot sequence arrowband composition can be greater than the coherence bandwidth of channel, frequency interval between the centre frequency of arrowband composition can also be a unequal interval, preferable, several discrete spectral lines with higher magnitude that the arrowband composition comprises are 1 spectral line.And the broadband become spectral line that branch shows can be for amplitude smooth or etc. the discrete spectral line of amplitude, further near the spectral line frequency domain arrowband composition of broadband composition is the discrete spectral line of 0 amplitude.
Be understood that it is preferred embodiment that the synchronizing pilot sequence is made up of two sub-synchronizing pilot sequences, also can form by a plurality of sub-synchronizing pilot sequences.In addition, if the sub-synchronizing pilot sequence that adopts is inequality, can also be following feature: length be identical, and, for any two sub-synchronizing pilot sequences, if each element of one of them sub-synchronizing pilot sequence is got conjugation, and and the element of the corresponding position of the sub-synchronizing pilot sequence of another one multiply each other, obtain a new sequence, and in the described new sequence, if an any continuously element is sued for peace, and if only if obtain when all elements are sued for peace in this new sequence with value maximum.
Fig. 2 is according to exemplary frequency deviation estimating method schematic flow sheet of the present invention.As shown in Figure 2, this method may further comprise the steps:
Step 201: the synchronizing pilot sequence that receives is carried out the time domain zero padding, and the synchronizing pilot sequence after the zero padding is carried out Fourier transform, to obtain the frequency domain over-sampling of synchronizing pilot sequence;
Here, transmitting terminal inserts the synchronizing pilot sequence in advance.A kind of synchronizing pilot sequence preferably is provided, be characterized in, this synchronizing pilot sequence is made up of two identical sub-synchronizing pilot sequence H1 and H2, sub-synchronizing pilot sequence is formed by stacking by two parts: a part is several arrowband compositions with higher-wattage spectral density, and other are the broadband compositions with lower-wattage spectral density; And several spectral lines of the both sides of the frequency spectrum of arrowband composition correspondence are set to 0, and the frequency domain interval between the frequency spectrum of adjacent arrowband composition correspondence is greater than the coherence bandwidth of channel, and can be unequal intervals.The feature of arrowband composition is, shows as continuous on the discrete spectrum of sub-synchronizing sequence some spectral lines or single-frequency pilot tone.The feature of broadband composition is, after the discrete spectrum of whole pilot frequency sequence is removed 0 value spectral line of arrowband composition and composition both sides, arrowband, shows as the multiple random sequence of amplitude such as, or multiple m sequence.
Be understood that it is preferred embodiment that the synchronizing pilot sequence is made up of two sub-synchronizing pilot sequences, also can form by a plurality of sub-synchronizing pilot sequences.In addition, if the sub-synchronizing pilot sequence that adopts is inequality, can also be following feature: length be identical, and, for any two sub-synchronizing pilot sequences, if each element of one of them sub-synchronizing pilot sequence is got conjugation, and and the element of the corresponding position of the sub-synchronizing pilot sequence of another one multiply each other, obtain a new sequence, and in the described new sequence, if an any continuously element is sued for peace, and if only if obtain when all elements are sued for peace in this new sequence with value maximum.
Fig. 3 is according to exemplary synchronization pilot symbol structure schematic diagram of the present invention.As shown in Figure 3, the synchronizing pilot symbol is made up of sub-synchronizing pilot sequence H1 and H2, and wherein H1 and H2 are the sub-synchronizing pilot sequences with strong delay correlation properties.
Fig. 4 is the spectrum amplitude schematic diagram according to exemplary synchronization pilot frequency sequence of the present invention.H1 or H2 preferably have spectrum amplitude feature as shown in Figure 4, i.e. stack high power single-frequency pilot frequency sequence on the sequence of frequency-flat.For fear of frequency domain interference to the single-frequency pilot frequency sequence, can also not pass the elm data between the single-frequency pilot frequency sequence and on the sub-band of contiguous frequency domain, such as, the spectrum signature of sub-synchronizing pilot sequence H1 or H2 is as shown in Figure 5.
For convenience of description, only adopted 3 single-frequency synchronizing pilot signals among Fig. 4 and Fig. 5, and the frequency interval between the single-frequency synchronizing pilot signal is 4 subcarrier widths.In fact, the present invention is also unrestricted to this.In the present invention, do not transmit the ratio of power of quantity, single-frequency synchronizing pilot signal power and the single-frequency synchronizing pilot sequence of the sub-band of data near frequency interval between the quantity of single-frequency synchronizing pilot signal, the single-frequency synchronizing pilot signal, the single-frequency synchronizing pilot signal, can adjust accordingly according to actual needs.And the frequency interval between the single-frequency synchronizing pilot both can be equally spaced, also can be unequal interval.
If the frequency interval between the single-frequency synchronizing pilot is not equally spaced,, so just can overcome the estimated frequency error that causes owing to channel fading such as adopting Fig. 6 and frequency spectrum shown in Figure 7.
Here, after receiving terminal receives the synchronizing pilot sequence of transmitting terminal transmission, at first the synchronizing pilot sequence that receives is carried out the time domain zero padding, and to the execution of the synchronizing pilot sequence after zero padding Fourier transform, to obtain the frequency domain over-sampling of synchronizing pilot sequence, wherein the precision of the number of zero padding and carrier frequency shift is relevant.Preferably the synchronizing pilot sequence after the zero padding is carried out FFT or DFT herein, but the present invention is also unrestricted to this, but can carries out any type of Fourier transform.
Step 202: on the discrete spectrum of the frequency domain over-sampling of synchronizing pilot sequence, calculate several discrete spectral lines amplitude square, and it is sued for peace, to obtain estimating sequence.Just, on the frequency spectrum of the frequency domain over-sampling of synchronizing pilot sequence, the power spectrum amplitude sum that has same frequency subcarrier sequence at interval according to the interval calculation of single-frequency pilot signal, to obtain estimating sequence, wherein the interval of the sub-carrier signal that is calculated is corresponding with the interval between the pilot frequency sequence.
Step 203: carry out Carrier frequency offset estimation according to estimating sequence.
Here, carry out Carrier frequency offset estimation and comprise according to estimating sequence: estimate the skew that sequencal estimation goes out the frequency sampling point according to described; And estimate described carrier frequency shift according to the skew of described frequency sampling point.
In addition, in above process, the scope that this frequency estimating methods can also the spread signal Frequency offset estimation, and not only the Frequency offset estimation scope is confined to 0.5 times of single-frequency pilot frequency sequence frequency interval.
The algorithm that frequency carrier skew of the present invention is estimated is specifically described below.
Receiving terminal carries out Carrier frequency offset estimation after executing time synchronized.If the synchronizing pilot sequence that receives is x (n), n=1 ... N, wherein N is the length of pilot frequency sequence.
At first the synchronizing pilot sequence is carried out the time domain zero padding, obtains:
Wherein P is an integer, and number (the P-1) * N of synchronizing pilot sequence zero padding is relevant with the precision of Frequency offset estimation.
Then the synchronizing pilot sequence after the zero padding is carried out Fourier transform, this sentences FFT is that example describes.But, it will be appreciated by those of skill in the art that the Fourier transform that to carry out other form herein, such as DFT etc.After executing the FFT conversion, can obtain the frequency domain over-sampling of synchronizing pilot sequence, that is:
Wherein k is the sequence number of frequency domain oversampled signals.
Then on the synchronizing pilot sequence spectrum, has the power spectrum amplitude sum of same frequency subcarrier sequence at interval according to the interval calculation of single-frequency pilot signal, promptly
V (j) is and estimates sequence, and wherein the quantity of single-frequency pilot tone is M, D
mBe the interval between m+1 single-frequency pilot tone and the 1st the single-frequency pilot tone, corresponding D
0Be defined as 0, as shown in Figure 7.
Can estimate according to estimating sequence V (j),
J wherein
RefIt is the spectrum position of predefined reference.Δ J is the skew of frequency sampling point, is to estimate peaked sequence number and J among the sequence V (j)
RefPoor.
Further, can draw carrier frequency shift this moment:
Wherein, Δ f is the interval between the OFDM subcarrier.This shows, according to the time domain zero padding, i.e. frequency domain over-sampling, the precision of Frequency offset estimation is relevant with frequency oversample factor P, so the present invention can accurately estimate the frequency shift (FS) less than the OFDM subcarrier spacing.And at receiving terminal, can also be further the power spectrum amplitude of multistage synchronizing pilot sequence be averaged, obtaining high SNR, and overcome the influence of channel fading Frequency offset estimation.
In the above process,, can only calculate V (J in order to improve the speed of Frequency offset estimation
Ref-maxoffset) ..., V (J
Ref+maxoffset).Wherein maxoffset is corresponding with the maximum carrier frequency skew that system can allow, and ref is the pairing position of maximum of estimating sequence when not having frequency shift (FS).At this moment, for estimate sequence V (j)=ref-maxoffset ..., ref+maxoffset} can calculate carrier frequency shift according to formula (4) and formula (5).
According to top description flow process and algorithm, specifically describe one embodiment of the present of invention below.
Fig. 8 is the spectrum amplitude schematic diagram of synchronizing pilot sequence according to an embodiment of the invention.As shown in Figure 8, here, the length of synchronizing pilot sequence is 128, the synchronizing pilot sequence has adopted 3 single-frequency pilot frequency sequences, and the frequency interval between them is 4 subcarrier widths, and do not transmit data between the single-frequency pilot frequency sequence and on 4 contiguous subcarriers, and the power of single-frequency pilot frequency sequence is 10 times of signal power on other sub-bands.In addition, the sub-band at single-frequency pilot frequency sequence place is the 60th, 64,68 sub-frequency bands, and the sub-band that does not transmit data on the synchronizing pilot sequence comprises that sequence number is 56～59,61～63,65～67, and 69～72 sub-band.
In the present embodiment, transmitting terminal produce a numerical value for+1 or-1 and length be 111 random sequence, this sequence is transmitted on the the 1st to the 55th and the 73rd to the 128th sub-frequency bands, and power magnitude is 1.
In the present embodiment, can not consider the influence of channel fading and Gauss's thermal noise.Can suppose that carrier frequency shift is-6.14 subcarrier spacings, on the basis of the thick time synchronized of receiving terminal, carries out Frequency offset estimation to the synchronizing pilot sequence that receives according to the present invention.In emulation, the maximum frequency deviation that system is set is 8 subcarrier spacings, and the oversample factor of frequency is 128, the amplitude of then estimating sequence as shown in Figure 9, the maximum correspondence of wherein estimating sequence the Frequency offset estimation value of carrier wave.
Figure 10 is according to exemplary frequency skew estimation unit schematic diagram of the present invention.As shown in figure 10, this device 1000 comprises: frequency domain over-sampling acquiring unit 1001 is used to obtain the frequency domain over-sampling of the synchronizing pilot sequence that receives; Estimate sequence calculation sequence 1002, be used for discrete spectrum at the frequency domain over-sampling of synchronizing pilot sequence, calculate several discrete spectral lines amplitude square, and it is sued for peace, to obtain estimating sequence; Carrier frequency offset estimation unit 1003 is used for carrying out Carrier frequency offset estimation according to estimating sequence; Its frequency domain over-sampling acquiring unit 1001 with estimate sequence calculation sequence 1002 and be connected, estimate sequence calculation sequence 1002 and be connected with Carrier frequency offset estimation unit 1003.
Preferably, frequency domain over-sampling acquiring unit 1001 comprises time domain zero padding unit and Fourier transformation unit, and wherein: time domain zero padding unit is used for the synchronizing pilot sequence that receives is carried out the time domain zero padding; Fourier transformation unit is used for the synchronizing pilot sequence after the zero padding is carried out Fourier transform; Time domain zero padding unit is connected with Fourier transformation unit.
Further, Fourier transformation unit 1002 is preferably FFT unit or DFT unit.
Figure 11 is Frequency offset estimation apparatus structure schematic diagram according to an embodiment of the invention.According to contrasting as can be known with Figure 10, the Carrier frequency offset estimation unit among Figure 11 comprises: maximum detection unit 1104 is used to determine to estimate the peaked sequence number of sequence; Reference value unit 1105 is used to preserve predefined reference number; Frequency offset estimation computing unit 1106 is used for carrying out subtraction to estimating peaked sequence number of sequence and predefined reference number, obtaining the skew of frequency sampling point, and according to the calculations of offset Carrier frequency offset estimation of described frequency sampling point; Wherein maximum detection unit 1104 is connected with Frequency offset estimation computing unit 1106, and reference value unit 1105 is connected with Frequency offset estimation computing unit 1106.
Obviously, Carrier frequency offset estimation device described above can be applied in various Carrier frequency offset estimation systems and the clock synchronization system.
Figure 12 is the structural representation of the clock synchronization system in the communication system according to an embodiment of the invention.As shown in figure 12, this system comprises: thick time synchronism apparatus 1201 is used for to received signal sequence and carries out initial time and estimate synchronously, and estimates synchronously that according to initial time sequence is carried out initial time delay adjustment to received signal; As above each described Carrier frequency offset estimation device 1202 is used for the received signal sequence through initial time delay adjustment is carried out Carrier frequency offset estimation; Carrier frequency shift compensation arrangement 1203, be used for according to Carrier frequency offset estimation to received signal sequence carry out carrier frequency shift compensation; Exact time synchronization device 1204 is used for estimating carrying out exact time synchronization through the received signal sequence of carrier frequency shift compensation, and estimates this received signal sequence is carried out the precise delay adjustment according to exact time synchronization; Wherein thick time synchronism apparatus 1201 is connected with Carrier frequency offset estimation device 1202, Carrier frequency offset estimation device 1202 is connected with carrier frequency shift compensation arrangement 1203, carrier frequency shift compensation arrangement 1203 be connected with exact time synchronization device 1204 with thick time synchronism apparatus 1201.
In summary, after using the present invention, can improve the precision of Carrier frequency offset estimation and the scope of Carrier frequency offset estimation significantly, and can significantly not increase complexity.
The above is preferred embodiment of the present invention only, is not to be used to limit protection scope of the present invention.Within the spirit and principles in the present invention all, any modification of being done, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (21)
1, carrier frequency deviation estimating method in a kind of communication system is characterized in that, this method may further comprise the steps:
A, receive the synchronizing pilot sequence, and obtain the frequency domain over-sampling of described synchronizing pilot sequence;
B, on the discrete spectrum of the frequency domain over-sampling of described synchronizing pilot sequence, calculate several discrete spectral lines amplitude square, and it is sued for peace, to obtain estimating sequence;
C, estimate sequence and carry out Carrier frequency offset estimation according to described.
2, method according to claim 1 is characterized in that, the described frequency domain over-sampling that obtains of steps A comprises:
A1, synchronizing pilot sequence execution time domain zero padding to receiving;
A2, the synchronizing pilot sequence after the time domain zero padding is carried out Fourier change, to obtain the frequency domain over-sampling of synchronizing pilot sequence.
3, method according to claim 2 is characterized in that, steps A 1 described execution time domain zero padding is: according to the precision of carrier frequency shift and the synchronizing pilot sequence that receives is carried out corresponding time domain zero padding.
4, method according to claim 2 is characterized in that, steps A 2 described execution Fourier transforms are: carry out fast fourier transform FFT or discrete Fourier transform (DFT) DFT.
5, method according to claim 1, it is characterized in that, described synchronizing pilot sequence comprises at least two sub-synchronizing pilot sequences, described sub-synchronizing pilot sequence comprises arrowband composition and broadband composition, and the amplitude of the discrete spectral line of arrowband composition correspondence is higher than the amplitude of the discrete spectral line of broadband composition correspondence.
6, method according to claim 5 is characterized in that, described each sub-synchronizing pilot sequence is identical.
7, method according to claim 5 is characterized in that, the frequency interval between the centre frequency of described sub-synchronizing pilot sequence arrowband composition is greater than the coherence bandwidth of channel.
8, method according to claim 5 is characterized in that, the frequency interval between the centre frequency of described sub-synchronizing pilot sequence arrowband composition is a unequal interval.
9, method according to claim 5 is characterized in that, the spectral line that described sub-synchronizing pilot sequence arrowband becomes branch to show is a single-frequency pilot tone spectral line.
10, method according to claim 5 is characterized in that, the spectral line that described sub-synchronizing pilot sequence broadband becomes branch to show further comprises: described spectral line is the smooth discrete spectral line of amplitude.
11, method according to claim 5 is characterized in that, the spectral line that described sub-synchronizing pilot sequence broadband becomes branch to show further comprises: described spectral line such as is at an amplitude.
12, method according to claim 5 is characterized in that, the spectral line that described sub-synchronizing pilot sequence broadband becomes branch to show further comprises: near the described spectral line frequency domain arrowband composition is the discrete spectral line of 0 amplitude.
13, method according to claim 1 is characterized in that: the frequency domain interval of several the single-frequency pilot frequency sequences of frequency interval in described synchronizing pilot sequence between described several the discrete spectral lines of step B is identical.
14, method according to claim 1 is characterized in that, described step C comprises:
C1, estimate the skew that sequencal estimation goes out the frequency sampling point according to described;
C2, estimate described carrier frequency shift according to the skew of described frequency sampling point.
According to each described method among the claim 1-14, it is characterized in that 15, described communication system is the orthogonal frequency division multiplex OFDM communication system.
16, Carrier frequency offset estimation device in a kind of communication system is characterized in that, this device comprises:
Frequency domain over-sampling acquiring unit is used to obtain the frequency domain over-sampling of the synchronizing pilot sequence that receives;
Estimate sequence calculation sequence, be used for discrete spectrum at the frequency domain over-sampling of described synchronizing pilot sequence, calculate several discrete spectral lines amplitude square, and it is sued for peace, to obtain estimating sequence;
The Carrier frequency offset estimation unit is used for estimating sequence and carrying out Carrier frequency offset estimation according to described;
Its frequency domain over-sampling acquiring unit with estimate sequence calculation sequence and be connected, estimate sequence calculation sequence and be connected with the Carrier frequency offset estimation unit.
17, Carrier frequency offset estimation device according to claim 16 is characterized in that, described frequency domain over-sampling acquiring unit comprises:
Time domain zero padding unit is used for the synchronizing pilot sequence that receives is carried out the time domain zero padding;
Fourier transformation unit is used for the synchronizing pilot sequence after the zero padding is carried out Fourier transform;
Wherein time domain zero padding unit is connected with Fourier transformation unit.
18, Carrier frequency offset estimation device according to claim 16 is characterized in that, described Carrier frequency offset estimation unit comprises:
Maximum detection unit determines to estimate the peaked sequence number of sequence;
The reference value unit is used to preserve predefined reference number;
The Frequency offset estimation computing unit is used for estimating the peaked sequence number of sequence and predefined reference number and carrying out subtraction described, obtaining the skew of frequency sampling point, and according to the calculations of offset Carrier frequency offset estimation of described frequency sampling point;
Wherein maximum detection unit is connected with the Frequency offset estimation computing unit, and the reference value unit is connected with the Frequency offset estimation computing unit.
19, Carrier frequency offset estimation device according to claim 17 is characterized in that, described Fourier transformation unit is FFT unit or DFT unit.
20, according to each described Carrier frequency offset estimation device among the claim 16-19, it is characterized in that described communication system is an ofdm communication system.
21, the clock synchronization system in a kind of communication system is characterized in that, this system comprises:
Thick time synchronism apparatus is used for to received signal sequence and carries out initial time and estimate synchronously, and estimates synchronously that according to described initial time sequence is carried out initial time delay adjustment to received signal;
As each described Carrier frequency offset estimation device among the claim 16-19, be used for the received signal sequence through initial time delay adjustment is carried out Carrier frequency offset estimation;
The carrier frequency shift compensation arrangement, be used for according to described Carrier frequency offset estimation to received signal sequence carry out carrier frequency shift compensation;
The exact time synchronization device is used for estimating carrying out exact time synchronization through the received signal sequence of carrier frequency shift compensation, and estimates this received signal sequence is carried out the precise delay adjustment according to described exact time synchronization;
Wherein thick time synchronism apparatus is connected with the Carrier frequency offset estimation device, and the Carrier frequency offset estimation device is connected with the carrier frequency shift compensation arrangement, and the carrier frequency shift compensation arrangement is connected with the exact time synchronization device with thick time synchronism apparatus.
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| CN102624661A (en) * | 2012-03-13 | 2012-08-01 | 电子科技大学 | Spectral peak prominence index-based spectral peak number identification method |
| CN104426821A (en) * | 2013-08-30 | 2015-03-18 | 普天信息技术研究院有限公司 | Uplink frequency compensation method |
| CN106101042A (en) * | 2016-05-31 | 2016-11-09 | 杭州电子科技大学 | A kind of CFO method of estimation based on many noises |
| CN106230762A (en) * | 2016-07-26 | 2016-12-14 | 广州海格通信集团股份有限公司 | Doppler frequency offset estimation method and system |
| US20170195159A1 (en) * | 2014-08-01 | 2017-07-06 | Lg Electronics Inc. | Method for transmitting and identifying pilot sequence in wireless communication system |
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| CN102624661A (en) * | 2012-03-13 | 2012-08-01 | 电子科技大学 | Spectral peak prominence index-based spectral peak number identification method |
| CN102624661B (en) * | 2012-03-13 | 2014-08-13 | 电子科技大学 | Spectral peak prominence index-based spectral peak number identification method |
| CN104426821A (en) * | 2013-08-30 | 2015-03-18 | 普天信息技术研究院有限公司 | Uplink frequency compensation method |
| CN104426821B (en) * | 2013-08-30 | 2018-01-19 | 普天信息技术研究院有限公司 | A kind of method of upstream frequency compensation |
| US20170195159A1 (en) * | 2014-08-01 | 2017-07-06 | Lg Electronics Inc. | Method for transmitting and identifying pilot sequence in wireless communication system |
| CN106101042A (en) * | 2016-05-31 | 2016-11-09 | 杭州电子科技大学 | A kind of CFO method of estimation based on many noises |
| CN106101042B (en) * | 2016-05-31 | 2019-05-14 | 杭州电子科技大学 | A kind of CFO estimation method based on more noises |
| CN106230762A (en) * | 2016-07-26 | 2016-12-14 | 广州海格通信集团股份有限公司 | Doppler frequency offset estimation method and system |
| CN106230762B (en) * | 2016-07-26 | 2019-06-18 | 广州海格通信集团股份有限公司 | Doppler frequency offset estimation method and system |
| CN112311710A (en) * | 2019-07-31 | 2021-02-02 | 华为技术有限公司 | Data processing method and communication device |
| WO2021017876A1 (en) * | 2019-07-31 | 2021-02-04 | 华为技术有限公司 | Data processing method and communication device |
| CN112311710B (en) * | 2019-07-31 | 2022-03-08 | 华为技术有限公司 | Data processing method and communication device |
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