CN101854322B - Frequency tracking method and system and frequency discriminator - Google Patents
Frequency tracking method and system and frequency discriminator Download PDFInfo
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- CN101854322B CN101854322B CN2009101305097A CN200910130509A CN101854322B CN 101854322 B CN101854322 B CN 101854322B CN 2009101305097 A CN2009101305097 A CN 2009101305097A CN 200910130509 A CN200910130509 A CN 200910130509A CN 101854322 B CN101854322 B CN 101854322B
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Abstract
The invention provides a frequency tracking method, a frequency tracking system and a frequency discriminator. The frequency tracking method comprises the following steps of: detecting frequency offset between user equipment and network equipment through a first frequency discrimination algorithm and a second frequency discrimination algorithm respectively, and acquiring a first frequency offset estimation result and a second frequency offset estimation result; if the smoothed value of the acquired first frequency offset estimation result is converged to the frequency discrimination range of the second frequency discrimination algorithm, adjusting and resetting the step length of the currently acquired second frequency offset estimation result, and performing frequency correction by using the adjusted second frequency offset estimation result. The frequency tracking method, the frequency tracking system and the frequency discriminator can guarantee the frequency offset capture range and the tracking accuracy.
Description
Technical field
The present invention relates to the communications field, relate in particular to a kind of frequency tracking method, system and frequency discriminator.
Background technology
3GPP (The 3rd Generation Partnership Project third generation gpp) Long Term Evolution (LTE; Long Term Evolution) project is the new technology development project of the maximum of 3GPP startup over the past two years; This with OFDM (Orthogonal Frequency Division Multiplexing; OFDM)/FDMA (Frequency Division Multiple Access; Frequency division multiple access) for the technology of core can be counted as " accurate 4G " technology, gathers around to have broad application prospects.But the LTE system is the same with other wireless communication system and since the crystal oscillator of user equipment (UE) (User Equipment) and base station very accurate in locating arrive same frequency, so have frequency deviation in the communication system, need frequency-tracking to proofread and correct.
The accuracy of LTE protocol requirement carrier wave frequency deviation must be within ± 0.1PPM in the observation area of a sub-frame (sub-frame) 1ms.Promptly only allow frequency deviation in ± 75Hz for the minimum carrier frequency 746MHz center frequency point of agreement regulation, this has proposed very high requirement to frequency-tracking.Frequency-tracking is generally accomplished through AFC (Auto Frequency Control, automatic frequency control) loop, and loop structure is as shown in Figure 1; Wherein, Frequency discriminator is used to detect the frequency deviation between UE and the base station, and it is the core of loop tracks, and its performance is relevant with the frequency offset estimating algorithm of employing; Loop filter is used for the smooth estimated value, adopts single order ring or second order loop usually; Voltage-controlled oscillator (VCO) is used to adjust frequency.
The inventor finds in realizing process of the present invention, in the prior art, adopts frequency discrimination algorithm TDPD_CP (TDPD:Time Domain Phase Difference, time domain phase place cross product; CP:Cyclic Prefix, Cyclic Prefix) as the AFC track loop of frequency discriminator, have the estimated accuracy deficiency; Residual frequency departure is difficult to reach the problem of the requirement of agreement 0.1ppm under the loop stable state, and residual frequency departure simulation result (10000ms) sketch map as shown in Figure 2 utilizes this algorithm; In initial frequency deviation is 1500Hz (ε=0.1, ε is the normalization frequency deviation, is defined as the ratio of actual frequency deviation and subcarrier spacing); Carrier frequency is 746MHz, and signal to noise ratio snr is 0dB, and bandwidth is 1.4MHz; Subcarrier spacing is under the simulated conditions of 15kHz, and in most cases residual frequency departure surpasses 0.1ppm.And employing frequency discrimination algorithm FDPD_RS (FDPD:Frequency Domain Phase Difference, frequency domain phase place cross product; RS:Reference Signal; Reference signal), has the too small problem of effective range of frequency discrimination, residual frequency departure simulation result (10000ms) sketch map as shown in Figure 3 as the AFC track loop of frequency discriminator; It is for being example with the OFDM of LTE system symbol data length N=2048, its time slot length N
Slot=15360, can get frequency offset estimating thus
In initial frequency deviation is 1500Hz (ε=0.1), and carrier frequency is 746MHz, and signal to noise ratio snr is 0dB; Bandwidth is 1.4MHz; Subcarrier spacing is under the simulated conditions of 15kHz, because actual frequency deviation surpasses effective estimation range of frequency discrimination algorithm, frequency lock loop can't converge to stable state all the time.
Summary of the invention
In order to solve the not enough and too small problem of capturing frequency deviation scope of frequency tracking method stable state accuracy of the prior art, the embodiment of the invention provides a kind of frequency tracking method, system and frequency discriminator.
The above-mentioned purpose of the embodiment of the invention realizes through following technical scheme:
A kind of frequency tracking method, said method comprises: detect the frequency deviation between the subscriber equipment and the network equipment respectively through the first frequency discrimination algorithm and the second frequency discrimination algorithm, obtain first frequency offset estimation result and second frequency offset estimation result; Wherein, with respect to the said second frequency discrimination algorithm, the frequency discrimination scope of the said first frequency discrimination algorithm is bigger, and precision is lower; If the smooth value of acquired first frequency offset estimation result converges in the frequency discrimination scope of the said second frequency discrimination algorithm; Then said second frequency offset estimation result of current acquisition is adjusted step-length and reset, utilize adjusted second frequency offset estimation result to carry out frequency correction.
A kind of frequency discriminator, said frequency discriminator comprises: the first frequency discrimination unit, be used for detecting the frequency deviation between the subscriber equipment and the network equipment through the first frequency discrimination algorithm, obtain first frequency offset estimation result; The second frequency discrimination unit is used for detecting the frequency deviation between the subscriber equipment and the network equipment through the second frequency discrimination algorithm, obtains second frequency offset estimation result; Wherein, with respect to the said second frequency discrimination algorithm, the frequency discrimination scope of the said first frequency discrimination algorithm is bigger, and precision is lower; Outer shroud locking decision unit is used to judge whether the smooth value of acquired first frequency offset estimation result converges in the frequency discrimination scope of the said second frequency discrimination algorithm; The frequency offset estimation result output unit; When being used in the frequency discrimination scope that smooth value in acquired first frequency offset estimation result converges on the said second frequency discrimination algorithm; Said second frequency offset estimation result is outputed to loop filter; And through said loop filter said second frequency offset estimation result is adjusted step-length and reset, utilize adjusted second frequency offset estimation result to carry out frequency correction through voltage-controlled oscillator (VCO) then.
A kind of frequency-tracking system, said system comprises loop filter, voltage-controlled oscillator (VCO) and aforesaid frequency discriminator.
The frequency tracking method of the embodiment of the invention, system and frequency discriminator have proposed two kinds of frequency discrimination algorithms of a kind of employing and have combined and carry out the scheme of frequency-tracking; Method, system and frequency discriminator through the embodiment of the invention; The capturing frequency deviation scope can be guaranteed, stable state accuracy can be guaranteed to follow the tracks of again.
Description of drawings
Accompanying drawing described herein is used to provide further understanding of the present invention, constitutes the application's a part, does not constitute qualification of the present invention.In the accompanying drawings:
Fig. 1 is an automatic frequency control system loop structure sketch map;
Fig. 2 is a time domain phase place cross product algorithm simulating sketch map as a result;
Fig. 3 is a frequency domain phase place cross product algorithm simulating sketch map as a result;
Fig. 4 is the frequency tracking method flow chart of the embodiment of the invention;
Fig. 5 is the CP repetitive structure sketch map of ofdm system;
Fig. 6 A is the descending RS mapping of the normal CP of a LTE system sketch map;
Fig. 6 B is the descending RS mapping of the extended CP of a LTE system sketch map;
Fig. 7 is the frequency tracking method flow chart of another embodiment of the present invention;
Fig. 8 is the frequency tracking method flow chart of another embodiment of the present invention;
The frequency deviation simulation result sketch map of Fig. 9 for adopting one of the embodiment of the invention to test;
Figure 10 is that the frequency discriminator of the embodiment of the invention is formed structured flowchart;
Figure 11 is the composition frame chart of the frequency-tracking system of the embodiment of the invention.
Embodiment
For the purpose, technical scheme and the advantage that make the embodiment of the invention is clearer,, the embodiment of the invention is explained further details below in conjunction with embodiment and accompanying drawing.At this, illustrative examples of the present invention and explanation thereof are used to explain the present invention, but not as to qualification of the present invention.
Embodiment one
The embodiment of the invention provides a kind of frequency tracking method, below in conjunction with accompanying drawing present embodiment is elaborated.
Fig. 4 is the method flow diagram of present embodiment, and please with reference to Fig. 4, the frequency tracking method of present embodiment mainly comprises:
401: detect the frequency deviation between the subscriber equipment and the network equipment through the first frequency discrimination algorithm and the second frequency discrimination algorithm, obtain first frequency offset estimation result and second frequency offset estimation result;
Wherein, with respect to the second frequency discrimination algorithm, the frequency discrimination scope of the said first frequency discrimination algorithm is bigger, and precision is lower.
In the present embodiment, this first frequency discrimination algorithm is TDPD_CP (TDPD:Time Domain Phase Difference, a time domain phase place cross product; CP:Cyclic Prefix, Cyclic Prefix) algorithm.
In the present embodiment, this second frequency discrimination algorithm is FDPD_RS (FDPD:Frequency Domain Phase Difference, a frequency domain phase place cross product; RS:Reference Signal, reference signal) algorithm.
402: whether the smooth value of judging acquired first frequency offset estimation result converges in the frequency discrimination scope of the second frequency discrimination algorithm;
Wherein, The smooth value of acquired first frequency offset estimation result can be realized through repeatedly first frequency offset estimation result current and that obtain is before averaged; Also can through to current and before repeatedly first frequency offset estimation result that obtains carry out comparing the back with a threshold value after the filtering and realize, present embodiment not with this as restriction.In addition; The mean value of repeatedly first frequency offset estimation result here can be the mean value of all first frequency offset estimation result of acquisition in the some cycles; Also can be the mean value of first frequency offset estimation result of predefined pre-determined number, the embodiment of the invention also not with this as restriction.
403: if the smooth value of acquired first frequency offset estimation result converges in the frequency discrimination scope of the said second frequency discrimination algorithm; Then said second frequency offset estimation result of current acquisition is adjusted step-length and reset, utilize adjusted second frequency offset estimation result to carry out frequency correction.
404: if the smooth value of acquired first frequency offset estimation result exceeds in the frequency discrimination scope of the said second frequency discrimination algorithm; Then said first frequency offset estimation result of current acquisition is adjusted step-length and successively decrease, utilize adjusted first frequency offset estimation result to carry out frequency correction.
In the present embodiment; Whether the smooth value of judging acquired first frequency offset estimation result converges in the frequency discrimination scope of the second frequency discrimination algorithm; Can through to current and before the acquired first frequency offset estimation result repeatedly back of adding up average or through realizing with the mode of a threshold value comparison after the filtering; Avoiding frequency offset estimation result maybe the inaccurate erroneous judgement that causes, but present embodiment not with this as restriction.
If the result who judges converges in the frequency discrimination scope of the second frequency discrimination algorithm for the smooth value of acquired first frequency offset estimation result; Explain that then the frequency discrimination scope reduces, second frequency offset estimation result that can use the second less relatively frequency discrimination algorithm of frequency discrimination scope to detect current frequency deviation acquisition is carried out frequency correction.
Loop filter receives this second frequency offset estimation result; After this second frequency offset estimation result adjusted step-length and handle; Second frequency offset estimation result after this processing is outputed to voltage-controlled oscillator (VCO), and voltage-controlled oscillator (VCO) utilizes second frequency offset estimation result after this processing to carry out frequency correction.Wherein, the work of loop filter is identical with prior art with the work of voltage-controlled oscillator (VCO), repeats no more at this.
In the present embodiment, the first frequency discrimination algorithm that the frequency discrimination scope is relatively large and the frequency discrimination precision is relatively low can be TDPD_CP (TDPD:Time Domain Phase Difference, time domain phase place cross product; CP:Cyclic Prefix, Cyclic Prefix) algorithm, but the embodiment of the invention not with this as restriction, describe in the face of TDPD_CP down.
Please with reference to Fig. 5, because ofdm system has cyclic prefix CP (Cyclic Prefix) usually, wherein, data division length is N, i.e. z
0, z
1... z
N-1, CP length is L, has repeated data division z
N-L, z
N-L+1... z
N-1, establishing and receiving signal is γ (n), the symbol original position is n
0, utilize CP repeatability to do the phase place cross product,
θ ∈ { π～π }, frequency offset estimation result does
{ 0.5～0.5}, wherein, ε is meant the normalization frequency deviation to ε ∈, is defined as actual frequency deviation
(unit: Hz) with subcarrier spacing Δ f (unit: ratio Hz).
In the present embodiment, the second frequency discrimination algorithm that the frequency discrimination scope is less relatively and the frequency discrimination precision is higher relatively can be FDPD_RS (FDPD:Frequency Domain Phase Difference, frequency domain phase place cross product; RS:Reference Signal, reference signal) algorithm, but the embodiment of the invention not with this as restriction, describe in the face of FDPD_RS down.
Please, can know that by LTE system descending RS mapping among Fig. 6 A, the 6B for 1,2 transmitting antenna, the RS symbol will repeat through its sub-carrier positions of slot time, defines following phase place cross product with reference to Fig. 6 A, Fig. 6 B,
θ ∈ { π～π }, wherein, Z
k(n
s) be n
sIndividual time slot, k number of sub-carrier place receiving symbol, P
k(n
s) be n
sIndividual time slot, this locality at k number of sub-carrier place produces the RS symbol, and then frequency offset estimation result does
Wherein, N
SlotThe expression slot length.
If the result who judges exceeds in the frequency discrimination scope of the second frequency discrimination algorithm for the smooth value of acquired first frequency offset estimation result; Explain that then the frequency discrimination scope is still very big; The second frequency discrimination algorithm that inapplicable frequency discrimination scope is less relatively; At this moment, first frequency offset estimation result of current acquisition is outputed to loop filter, exchange after synchronizing length successively decreases through loop filter; First frequency offset estimation result after output is handled is to voltage-controlled oscillator (VCO), and voltage-controlled oscillator (VCO) continues to adopt first frequency offset estimation result after handling to carry out frequency correction.
According to present embodiment; In order to reach better tracking effect, employed loop filter can be variable adjustment step-length single order ring, so can when tracking is initial, adopt big step-length; Adopt little step-length during stable state, initially be decremented to the configuration low value to stable state transition step-length.
The embodiment of the invention adopts the mode of two kinds of frequency discrimination algorithm combination; Detect frequency deviation through the first frequency discrimination algorithm that the frequency discrimination scope is relatively large and the frequency discrimination precision is relatively low earlier; Detect frequency deviation through the second frequency discrimination algorithm that the frequency discrimination scope is less relatively and the frequency discrimination precision is higher relatively again; The capturing frequency deviation scope can be guaranteed, tracking accuracy can be guaranteed again.
Embodiment two
The embodiment of the invention also provides a kind of frequency tracking method, below in conjunction with accompanying drawing present embodiment is elaborated.
Fig. 7 is the method flow diagram of present embodiment; Please with reference to Fig. 7, present embodiment is on the basis of embodiment one, in the process of the second frequency discrimination algorithm work of employing; Promptly carry out in the process of frequency correction with second frequency offset estimation result; A preferred embodiment of this frequency tracking method, as shown in Figure 7, the method for present embodiment mainly comprises:
701: whether the smooth value of judging acquired second frequency offset estimation result satisfies protocol requirement;
702: if the smooth value of acquired second frequency offset estimation result satisfies protocol requirement, then the said second frequency deviation result of current acquisition is adjusted step-length and successively decrease, utilize adjusted second frequency offset estimation result to carry out frequency correction;
703: if the smooth value unmet protocol requirement of acquired second frequency offset estimation result, then the said second frequency deviation result to current acquisition adjusts the step-length replacement, utilizes adjusted second frequency offset estimation result to carry out frequency correction.
In the present embodiment; Whether the smooth value of judging acquired second frequency offset estimation result satisfies protocol requirement; Also can through to current and before the acquired second frequency offset estimation result repeatedly back of adding up average or through realizing with the mode of another threshold value comparison after the filtering; Avoiding frequency offset estimation result maybe the inaccurate erroneous judgement that causes, but present embodiment not with this as restriction.
If the result who judges satisfies protocol requirement for the smooth value of acquired second frequency offset estimation result; Then explanation frequency deviation at this moment at this moment, can output to loop filter with second frequency offset estimation result of current acquisition in user's tolerance interval; Through loop filter the loop filtering step-length is successively decreased; Second frequency offset estimation result after obtaining handling outputs to voltage-controlled oscillator (VCO), and voltage-controlled oscillator (VCO) is that second frequency offset estimation result after this processing capable of using is carried out frequency correction.
If the result who judges is the smooth value unmet protocol requirement of acquired second frequency offset estimation result; Then explanation frequency deviation at this moment still can not reach requirement, at this moment, can second frequency offset estimation result of current acquisition be outputed to loop filter; Through loop filter loop filtering adjustment step-length is reset; Second frequency offset estimation result after obtaining handling outputs to voltage-controlled oscillator (VCO), and voltage-controlled oscillator (VCO) is that second frequency offset estimation result after this processing capable of using is carried out frequency correction.
According to present embodiment; In order to reach better tracking effect, employed loop filter can be variable adjustment step-length single order ring, so can when tracking is initial, adopt big step-length; Adopt little step-length during stable state, initially be decremented to the configuration low value to stable state transition step-length.
The embodiment of the invention adopts the mode of two kinds of frequency discrimination algorithm combination; Detect frequency deviation through the first frequency discrimination algorithm that the frequency discrimination scope is relatively large and the frequency discrimination precision is relatively low earlier; Detect frequency deviation through the second frequency discrimination algorithm that the frequency discrimination scope is less relatively and the frequency discrimination precision is higher relatively again; The capturing frequency deviation scope can be guaranteed, tracking accuracy can be guaranteed again.
Embodiment three
The embodiment of the invention also provides a kind of frequency tracking method, below in conjunction with accompanying drawing present embodiment is elaborated.
Fig. 8 is the method flow diagram of present embodiment; Please with reference to Fig. 8, present embodiment be embodiment one and or the basis of embodiment two on, in the process of the second frequency discrimination algorithm work of employing; Promptly carry out in the process of frequency correction with second frequency offset estimation result; Another preferred embodiment of this frequency tracking method, as shown in Figure 8, the method for present embodiment mainly comprises:
801: judge whether the smooth value of acquired first frequency offset estimation result exceeds the frequency discrimination scope of the said second frequency discrimination algorithm;
802: if the smooth value of acquired first frequency offset estimation result exceeds the frequency discrimination scope of the said second frequency discrimination algorithm; Then said first frequency offset estimation result of current acquisition is adjusted step-length and reset, utilize adjusted first frequency offset estimation result to carry out frequency correction;
803: if the smooth value of acquired first frequency offset estimation result does not exceed the frequency discrimination scope of the said second frequency discrimination algorithm; Then said second frequency offset estimation result of current acquisition is adjusted step-length and successively decrease, utilize adjusted second frequency offset estimation result to carry out frequency correction.
In the present embodiment; Judge whether the smooth value of acquired first frequency offset estimation result exceeds the frequency discrimination scope of the second frequency discrimination algorithm; Also can through to current and before the acquired first frequency offset estimation result repeatedly back of adding up average or through realizing with the mode of another threshold value comparison after the filtering; Avoiding frequency offset estimation result maybe the inaccurate erroneous judgement that causes, but present embodiment not with this as restriction.
If the result who judges exceeds the frequency discrimination scope of the second frequency discrimination algorithm for the smooth value of acquired first frequency offset estimation result; Then explanation this moment, the second frequency discrimination algorithm was inapplicable, at this moment, first frequency offset estimation result of current acquisition was outputed to loop filter; Through loop filter the loop filtering step-length is reset; First frequency offset estimation result after obtaining handling outputs to voltage-controlled oscillator (VCO), and voltage-controlled oscillator (VCO) is that first frequency offset estimation result after this processing capable of using is carried out frequency correction.
If the result who judges does not exceed the frequency discrimination scope of the second frequency discrimination algorithm for the smooth value of acquired first frequency offset estimation result; Explain that then the second frequency discrimination algorithm stands good, at this moment, second frequency offset estimation result of current acquisition is outputed to loop filter; Through loop filter the loop filtering step-length is successively decreased; Second frequency offset estimation result after obtaining handling outputs to voltage-controlled oscillator (VCO), and voltage-controlled oscillator (VCO) is that second frequency offset estimation result after this processing capable of using is carried out frequency correction.
Whether the smooth value that in the present embodiment, also can judge the acquired second frequency deviation result simultaneously satisfies protocol requirement.About judging whether acquired second frequency offset estimation result satisfies protocol requirement and be described in embodiment two, repeats no more at this.
According to present embodiment; In order to reach better tracking effect, employed loop filter can be variable adjustment step-length single order ring, so can when tracking is initial, adopt big step-length; Adopt little step-length during stable state, initially be decremented to the configuration low value to stable state transition step-length.
Fig. 9 is the simulation result sketch map of the frequency-tracking of the being done experiment of the frequency tracking method of the employing embodiment of the invention, and in experiment shown in Figure 9, simulated conditions is: initial frequency deviation is 1500Hz (ε=0.1); Carrier frequency is 746MHz; Signal to noise ratio snr is 0dB; Transmitted bandwidth is 1.4MHz; Subcarrier spacing is 15kHz, can know according to residual frequency departure simulation result (10000ms) shown in Figure 9, through the method for the embodiment of the invention, both can realize that frequency deviation caught fast, can obtain extraordinary locking performance in stable state again.
The embodiment of the invention adopts the mode of two kinds of frequency discrimination algorithm combination; Detect frequency deviation through the first frequency discrimination algorithm that the frequency discrimination scope is relatively large and the frequency discrimination precision is relatively low earlier; Detect frequency deviation through the second frequency discrimination algorithm that the frequency discrimination scope is less relatively and the frequency discrimination precision is higher relatively again; The capturing frequency deviation scope can be guaranteed, tracking accuracy can be guaranteed again.
Embodiment four
The embodiment of the invention also provides a kind of frequency discriminator, below in conjunction with accompanying drawing present embodiment is elaborated.
Figure 10 is the composition frame chart of the frequency discriminator of present embodiment, and please with reference to Figure 10, the frequency discriminator of present embodiment mainly comprises:
The first frequency discrimination unit 101 is used for detecting the frequency deviation between the subscriber equipment and the network equipment through the first frequency discrimination algorithm, obtains first frequency offset estimation result;
The second frequency discrimination unit 102 is used for detecting the frequency deviation between the subscriber equipment and the network equipment through the second frequency discrimination algorithm, obtains second frequency offset estimation result;
Wherein, the frequency between the subscriber equipment and the network equipment is to receive through rf receiver unit, and this is the content of prior art, repeats no more at this.
Outer shroud locking decision unit 103 be used to judge whether the smooth value of acquired first frequency offset estimation result converges in the frequency discrimination scope of the second frequency discrimination algorithm, and the result that will judge sends to frequency offset estimation result output unit 104;
Frequency offset estimation result output unit 104; When being used in the frequency discrimination scope that smooth value in acquired first frequency offset estimation result converges on the second frequency discrimination algorithm; Second frequency offset estimation result of current acquisition is outputed to loop filter; And through said loop filter said second frequency offset estimation result is adjusted step-length and reset, utilize adjusted second frequency offset estimation result to carry out frequency correction through voltage-controlled oscillator (VCO) then.
In the present embodiment; When frequency offset estimation result output unit 104 also is used in the frequency discrimination scope that smooth value in acquired first frequency offset estimation result exceeds the second frequency discrimination algorithm; First frequency offset estimation result of current acquisition is outputed to loop filter; And through said loop filter said first frequency offset estimation result is adjusted step-length and successively decrease, utilize adjusted first frequency offset estimation result to carry out frequency correction through voltage-controlled oscillator (VCO) then.
According to present embodiment, said frequency discriminator can also comprise:
Interior ring losing lock decision unit 105; Be used for second frequency offset estimation result being outputed to the process of loop filter at frequency offset estimation result output unit 104; Whether the smooth value of judging acquired second frequency offset estimation result satisfies protocol requirement, and the result that will judge sends to frequency offset estimation result output unit 104.
Frequency offset estimation result output unit 104 also is used for when the smooth value of acquired second frequency offset estimation result satisfies protocol requirement; The second frequency deviation result of current acquisition is outputed to loop filter; And through said loop filter said second frequency offset estimation result is adjusted step-length and successively decrease, utilize adjusted second frequency offset estimation result to carry out frequency correction through voltage-controlled oscillator (VCO) then; And when the smooth value unmet protocol requirement of acquired second frequency offset estimation result; Second frequency offset estimation result of current acquisition is outputed to loop filter; And through said loop filter said second frequency offset estimation result is adjusted step-length and reset, utilize adjusted second frequency offset estimation result to carry out frequency correction through voltage-controlled oscillator (VCO) then.
According to present embodiment, said frequency discriminator can also comprise:
Outer shroud losing lock decision unit 106; Be used for the second frequency deviation result being outputed to the course of work of loop filter at frequency offset estimation result output unit 104; Judge whether the smooth value of acquired first frequency offset estimation result exceeds the frequency discrimination scope of the second frequency discrimination algorithm, and the result that will judge sends to frequency offset estimation result output unit 104.
Frequency offset estimation result output unit 104 also is used for when the smooth value of acquired first frequency offset estimation result exceeds the frequency discrimination scope of the said second frequency discrimination algorithm; First frequency offset estimation result of current acquisition is outputed to loop filter; And through said loop filter said first frequency offset estimation result is adjusted step-length and reset, utilize adjusted first frequency offset estimation result to carry out frequency correction through voltage-controlled oscillator (VCO) then; And when the smooth value of acquired first frequency offset estimation result does not exceed the frequency discrimination scope of the said second frequency discrimination algorithm; Second frequency offset estimation result of current acquisition is outputed to loop filter; And through said loop filter said second frequency offset estimation result is adjusted step-length and successively decrease, utilize adjusted second frequency offset estimation result to carry out frequency correction through voltage-controlled oscillator (VCO) then.
Wherein, loop filter can be variable adjustment step-length single order ring.
The function of each part of the frequency discriminator of present embodiment is the function of step that is used to realize the frequency tracking method of embodiment one-embodiment three, because embodiment one-embodiment three has done detailed description to each function, repeats no more at this.
Through the frequency discriminator of the embodiment of the invention, the mode of having used two kinds of frequency discrimination algorithms to combine is carried out frequency-tracking, both can realize that frequency deviation catches fast, can obtain extraordinary locking performance in stable state again.
Embodiment five
The embodiment of the invention also provides a kind of frequency-tracking system, below in conjunction with accompanying drawing present embodiment is elaborated.
Figure 11 is the composition frame chart of the frequency-tracking system of present embodiment, and is shown in figure 11, and the frequency-tracking system of present embodiment has comprised frequency discriminator 111, loop filter 112 and the voltage-controlled oscillator (VCO) 113 of embodiment three, wherein:
The frequency discriminator 111 of present embodiment has been used the frequency tracking method of embodiment one-embodiment three; Realized subscriber equipment to the network equipment; Like the frequency detecting and the tracking of base station, concrete implementation procedure is described in embodiment one, embodiment two and embodiment three, repeats no more at this.
The loop filter 112 of present embodiment is used for adjusting variable adjustment step-length according to the frequency offset estimation result of frequency discriminator 111; The adjustment amount that obtains a frequency offset estimation result is exported to voltage-controlled oscillator (VCO); Its operation principle is identical with prior art with process, repeats no more at this.This loop filter 112 can be variable adjustment step-length single order ring, so can when tracking is initial, adopt big step-length, adopts little step-length during stable state, initially is decremented to the configuration low value to stable state transition step-length.
The voltage-controlled oscillator (VCO) 113 of present embodiment is used for carrying out frequency correction according to the adjustment amount of the frequency offset estimation result of loop filter 112 outputs, and its operation principle is identical with prior art with process, repeats no more at this.
Through the frequency-tracking system of the embodiment of the invention, because the mode that frequency discriminator 111 has adopted two kinds of frequency discrimination algorithms to combine is carried out frequency-tracking, both can realize that frequency deviation catches fast, can obtain extraordinary locking performance in stable state again.
Above-described specific embodiment; The object of the invention, technical scheme and beneficial effect have been carried out further explain, and institute it should be understood that the above is merely specific embodiment of the present invention; And be not used in qualification protection scope of the present invention; All within spirit of the present invention and principle, any modification of being made, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (13)
1. a frequency tracking method is characterized in that, said method comprises:
Detect the frequency deviation between the subscriber equipment and the network equipment respectively through the first frequency discrimination algorithm and the second frequency discrimination algorithm, obtain first frequency offset estimation result and second frequency offset estimation result; Wherein, with respect to the said second frequency discrimination algorithm, the frequency discrimination scope of the said first frequency discrimination algorithm is bigger, and precision is lower;
If the smooth value of acquired first frequency offset estimation result converges in the frequency discrimination scope of the said second frequency discrimination algorithm; Then said second frequency offset estimation result of current acquisition is adjusted step-length and reset, utilize adjusted second frequency offset estimation result to carry out frequency correction.
2. method according to claim 1 is characterized in that, said method also comprises:
Whether the smooth value of judging acquired second frequency offset estimation result meets the demands;
If the smooth value of acquired second frequency offset estimation result meets the demands, then said second frequency offset estimation result of current acquisition is adjusted step-length and successively decrease, utilize adjusted second frequency offset estimation result to carry out frequency correction.
3. method according to claim 2 is characterized in that:
If the smooth value backlog demand of acquired second frequency offset estimation result is then adjusted step-length to said second frequency offset estimation result of current acquisition and reset, utilize adjusted second frequency offset estimation result to carry out frequency correction.
4. method according to claim 1 and 2 is characterized in that, said method also comprises:
If the smooth value of acquired first frequency offset estimation result exceeds the frequency discrimination scope of the said second frequency discrimination algorithm; Then said first frequency offset estimation result of current acquisition is adjusted step-length and reset, utilize adjusted first frequency offset estimation result to carry out frequency correction.
5. method according to claim 1 is characterized in that:
The said first frequency discrimination algorithm is a time domain phase place cross product algorithm, and the said second frequency discrimination algorithm is a frequency domain phase place cross product algorithm.
6. method according to claim 1 is characterized in that, said adjustment step-length is reset and adopted variable adjustment step-length single order ring to realize.
7. a frequency discriminator is characterized in that, said frequency discriminator comprises:
The first frequency discrimination unit is used for detecting the frequency deviation between the subscriber equipment and the network equipment through the first frequency discrimination algorithm, obtains first frequency offset estimation result;
The second frequency discrimination unit is used for detecting the frequency deviation between the subscriber equipment and the network equipment through the second frequency discrimination algorithm, obtains second frequency offset estimation result; Wherein, with respect to the said second frequency discrimination algorithm, the frequency discrimination scope of the said first frequency discrimination algorithm is bigger, and precision is lower;
Outer shroud locking decision unit is used to judge whether the smooth value of acquired first frequency offset estimation result converges in the frequency discrimination scope of the said second frequency discrimination algorithm;
The frequency offset estimation result output unit; When being used in the frequency discrimination scope that smooth value in acquired first frequency offset estimation result converges on the said second frequency discrimination algorithm; Second frequency offset estimation result of current acquisition is outputed to loop filter; And through said loop filter said second frequency offset estimation result is adjusted step-length and reset, utilize adjusted second frequency offset estimation result to carry out frequency correction through voltage-controlled oscillator (VCO) then.
8. frequency discriminator according to claim 7 is characterized in that, said frequency discriminator also comprises:
In ring losing lock decision unit, be used for said second frequency offset estimation result being outputed to the process of loop filter at said frequency offset estimation result output unit, judge whether the smooth value of acquired second frequency offset estimation result meets the demands;
Said frequency offset estimation result output unit also is used for when the smooth value of acquired second frequency offset estimation result meets the demands; Second frequency offset estimation result of current acquisition is outputed to loop filter; And through said loop filter said second frequency offset estimation result is adjusted step-length and successively decrease, utilize adjusted second frequency offset estimation result to carry out frequency correction through voltage-controlled oscillator (VCO) then.
9. frequency discriminator according to claim 8 is characterized in that:
Said frequency offset estimation result output unit also is used for when the smooth value backlog demand of acquired second frequency offset estimation result; Second frequency offset estimation result of current acquisition is outputed to loop filter; And through said loop filter said second frequency offset estimation result is adjusted step-length and reset, utilize adjusted second frequency offset estimation result to carry out frequency correction through voltage-controlled oscillator (VCO) then.
10. frequency discriminator according to claim 7 is characterized in that, said frequency discriminator also comprises:
Outer shroud losing lock decision unit; Be used for said second frequency offset estimation result being outputed to the process of loop filter, judge whether the smooth value of acquired first frequency offset estimation result exceeds the frequency discrimination scope of the said second frequency discrimination algorithm at said frequency offset estimation result output unit;
Said frequency offset estimation result output unit also is used for when the smooth value of acquired first frequency offset estimation result exceeds the frequency discrimination scope of the said second frequency discrimination algorithm; First frequency offset estimation result of current acquisition is outputed to loop filter; And through said loop filter said first frequency offset estimation result is adjusted step-length and reset, utilize adjusted first frequency offset estimation result to carry out frequency correction through voltage-controlled oscillator (VCO) then.
11., it is characterized in that according to each described frequency discriminator of claim 7-10:
The said first frequency discrimination unit adopts time domain phase place cross product algorithm to detect the frequency between the subscriber equipment and the network equipment;
The said second frequency discrimination unit adopts frequency domain phase place cross product algorithm to detect the frequency between the subscriber equipment and the network equipment.
12. a frequency-tracking system is characterized in that, said frequency-tracking system comprises each described frequency discriminator of loop filter, voltage-controlled oscillator (VCO) and claim 7-10.
13. frequency-tracking according to claim 12 system is characterized in that: said loop filter adopts variable adjustment step-length single order ring adjustment step-length to reset or the adjustment step-length is successively decreased.
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| CN102215202A (en) * | 2011-07-11 | 2011-10-12 | 合肥东芯通信股份有限公司 | Device and method for estimating frequency deviation of LTE (long term evolution) system |
| CN104536022B (en) * | 2015-01-06 | 2017-02-22 | 中国人民解放军国防科学技术大学 | Low complexity frequency detector designing method for GNSS weak signal tracking |
| CN105991484B (en) * | 2015-01-30 | 2020-04-03 | 中兴通讯股份有限公司 | Frequency offset estimation method and device |
| CN112672283B (en) * | 2020-12-28 | 2022-04-05 | 北京邮电大学 | Processing device and method for tracking loop error in positioning receiver |
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| WO1998054875A1 (en) * | 1997-05-28 | 1998-12-03 | Kabushiki Kaisha Kenwood | Carrier recovery in dab receivers |
| CN1855905A (en) * | 2005-04-29 | 2006-11-01 | 中国科学院上海微系统与信息技术研究所 | Hierarchical parallel frequency catching method |
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| WO1998054875A1 (en) * | 1997-05-28 | 1998-12-03 | Kabushiki Kaisha Kenwood | Carrier recovery in dab receivers |
| CN1855905A (en) * | 2005-04-29 | 2006-11-01 | 中国科学院上海微系统与信息技术研究所 | Hierarchical parallel frequency catching method |
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