CN102571221A - Method and equipment for estimating Doppler frequency shift in wireless communication system - Google Patents
Method and equipment for estimating Doppler frequency shift in wireless communication system Download PDFInfo
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- CN102571221A CN102571221A CN2010106008831A CN201010600883A CN102571221A CN 102571221 A CN102571221 A CN 102571221A CN 2010106008831 A CN2010106008831 A CN 2010106008831A CN 201010600883 A CN201010600883 A CN 201010600883A CN 102571221 A CN102571221 A CN 102571221A
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Abstract
The invention relates to a method and equipment for estimating a Doppler frequency shift in a wireless communication system. The method for estimating the Doppler frequency shift in the wireless communication system comprises the following steps of: firstly obtaining power spectral density information of a receiving signal in an uplink by the equipment; and then estimating the Doppler frequency shift according to the power spectral density information. The method and the equipment for estimating the Doppler frequency shift in the wireless communication system have the advantages that: the estimated Doppler frequency shift has high accuracy; and a mobile transmission system can be optimized, the synchronous distortion can be compensated and the system performance can be improved.
Description
Technical field
The present invention relates to wireless communication field, relate in particular to the method and apparatus that carries out the estimation of Doppler frequency displacement at wireless communication system.
Background technology
In the LTE system, the rate travel of Doppler frequency shift or perhaps subscriber equipment (UE) is the significant variable that moves fading channel.It is fast more that UE moves, and Doppler frequency shift is just big more, and the channel variable change is fast more.Based among the 3GPP to the demand of LTE system, in the LTE system, high performance service support need be provided for the subscriber equipment of 15 to 120km/h high translational speeds.Between Cellular Networks, need to support the translational speed of 120km/h to 350km/h (even relying on frequency bandwidth can support 500km/h), and this translational speed will be damaged the orthogonal property of SC-FDMA in the LTE system up-link.Therefore, the base station need be estimated Doppler frequency shift, so that compensate.
Existing mainly contain five types of Doppler's estimation techniques: based on the method for level crossing rate (lcr) (LCR), based on the method for zero-crossing rate (ZCR), based on the method for auto-correlation function (ACF), based on the method for covariance (COV) and based on the method for pattern recognition (PR).
Wherein, can effectively be divided into UE speed slowly based on the method for ACF, in or fast.But its speed is divided too rough, is difficult to meet practical situation; And it is very sensitive based on the method for COV to these factors such as the angle of arrival of additive white Gaussian noise (AWGN), this factor of Lay (K) and straight line sighting distance (LOS) element; Method based on PR needs intensive calculations; Method based on LCR and ZCR serious misjudgment can occur when the SNR signal to noise ratio is low.Of paramount importance is that above-mentioned each method only adopts in the FDD system, and can not be applied in the TDD system, especially can not be applied to TD-LTE.
Summary of the invention
The purpose of this invention is to provide a kind of method and apparatus that carries out the estimation of Doppler frequency displacement at wireless communication system.
According to an aspect of the present invention, a kind of method of carrying out the estimation of Doppler frequency displacement at wireless communication system is provided, wherein, this method may further comprise the steps:
A obtains the power spectral density information that receives signal in the up link;
B comes the estimation of Doppler frequency displacement according to said power spectral density information.
According to another aspect of the present invention, a kind of equipment that carries out the estimation of Doppler frequency displacement at wireless communication system is provided also, wherein, this equipment comprises:
First deriving means is used for obtaining the power spectral density information that up link receives signal;
The frequency displacement estimating device is used for coming the estimation of Doppler frequency displacement according to said power spectral density information.
Compared with prior art, the present invention has the following advantages: the Doppler frequency shift accuracy of 1) estimating is high; 2) can the optimization mobile transmission system and compensation synchronous distortion, improve systematic function.
Description of drawings
Through reading the detailed description of doing with reference to following accompanying drawing that non-limiting example is done, it is more obvious that other features, objects and advantages of the present invention will become:
Fig. 1 is the wireless communication system topology figure of one aspect of the invention;
Fig. 2 is the method flow diagram that carries out the estimation of Doppler frequency displacement at wireless communication system of one aspect of the invention;
Fig. 3 is the method flow diagram that carries out the estimation of Doppler frequency displacement at wireless communication system of another aspect of the present invention;
Fig. 4 is the method flow diagram that carries out the estimation of Doppler frequency displacement at wireless communication system of another aspect of the present invention;
Fig. 5 is the equipment sketch map that carries out the estimation of Doppler frequency displacement at wireless communication system of another aspect of the present invention;
Fig. 6 is the equipment sketch map that carries out the estimation of Doppler frequency displacement at wireless communication system of one aspect of the invention;
Fig. 7 is the equipment sketch map that carries out the estimation of Doppler frequency displacement at wireless communication system of another aspect of the present invention;
Fig. 8 is the equipment sketch map that carries out the estimation of Doppler frequency displacement at wireless communication system of another aspect of the present invention;
Fig. 9 is the equipment sketch map that carries out the estimation of Doppler frequency displacement at wireless communication system of another aspect of the present invention;
Figure 10 is a relatively sketch map of the estimated Doppler frequency shift of the present invention and existing Doppler frequency shift evaluation method;
Figure 11 is the present invention's estimated Doppler frequency shift sketch map when different uplink-downlink configuration;
Same or analogous Reference numeral is represented same or analogous parts in the accompanying drawing.
Embodiment
Below in conjunction with accompanying drawing the present invention is described in further detail.
Fig. 1 shows the wireless communication system topology figure of one aspect of the invention.Said wireless communication system comprises: subscriber equipment 11, subscriber equipment 12 ... subscriber equipment 1K and equipment 2.Wherein, each subscriber equipment can be any can including but not limited to the mobile electronic device of wireless mode and base station communication: mobile phone, PDA, Vehicle mounted station etc.; Said equipment 2 includes but not limited to; Base station or eNodeB, network controller etc.; Said wireless communication system includes but not limited to: 3G, LTE or WiMAX system etc.
In addition; As a kind of optimal way; TDD mode (time-division duplexing mode is adopted in each subscriber equipment in this wireless communication system and base station 2; TDD mode) receives and sends messages, but it should be appreciated by those skilled in the art that the pattern of each subscriber equipment and base station transceiver information is not that the above exceeds.
Fig. 2 shows the flow chart in the method for carrying out the estimation of Doppler frequency displacement of wireless communication system of one aspect of the invention.Wherein, subscriber equipment 1 be subscriber equipment 11, subscriber equipment 12 ... any one among the subscriber equipment 1K; Said equipment 2 is eNodeB.
Concrete, in step S1, subscriber equipment 1 sends signal to equipment 2.
Then, in step S2, equipment 2 receives the signal that sends from subscriber equipment 1.
Then, in step S3, equipment 2 obtains the power spectral density information S (f) that receives signal.The mode that equipment 2 obtains the power spectral density information S (f) that receives signal includes but not limited to: 1) Classical Spectrum method of estimation; For example, period map method etc.; 2) modern spectral estimation method; For example, the parameter model spectrum is estimated and nonparametric model is composed estimation etc.
Then, in step S4, equipment 2 comes estimation of Doppler frequency displacement f according to said power spectral density information
m
Fig. 3 shows the flow chart in the method for carrying out the estimation of Doppler frequency displacement of wireless communication system of another aspect of the present invention.
Concrete, step S1 to S3 describes in detail in the embodiment shown in Figure 2, comprises by reference at this, no longer repeats.
Then, in step S41, equipment 2 obtains an adaptive threshold according to said power spectral density information.For example, the adaptive threshold Sth that obtains according to power spectral density information of equipment 2 is:
Wherein, S (0) expression frequency 0 place's power spectrum value, the value of S (1/T) expression power spectrum 1/T Hz place frequency spectrum, T is the up-downgoing change-over period, and α representes coefficient, and as a kind of optimal way, α equals 2.
It should be appreciated by those skilled in the art that above-mentioned adaptive threshold S
ThOnly just list, but not be used to limit the present invention, in fact, adaptive threshold S
ThCan be according to actual other different values of choosing.
Then, in step S42, equipment 2 compares the power spectral density value and the said adaptive threshold at different frequency place in regular turn, obtains first the power spectral density power spectral density value frequency values of living in greater than said adaptive threshold.For example, equipment 2 is in regular turn with the different frequency place, for example, and f
1, f
2... f
N, wherein, f
1＜f
2＜...＜f
N, power spectral density value: S (f
1), S (f
2) ... S (f
N), respectively with adaptive threshold S
ThRelatively, obtain for example, to be power spectral density value S (f first greater than the power spectral density power spectral density value frequency values of living in of said adaptive threshold
i) frequency values f of living in
i
At last, in step S43, equipment 2 is estimated said Doppler frequency shift according to frequency values that is obtained and said reception signal center frequency value.For example, equipment 2 is according to the frequency values f that is obtained
iDoppler frequency shift f with said reception signal center frequency value (the carrier frequency value of signal just) estimation
mFor:
f
m＝f
c-f
i。
Fig. 4 shows the flow chart in the method for carrying out the estimation of Doppler frequency displacement of wireless communication system of another aspect of the present invention.
Concrete, step S1 to S3 and S41 describe in detail in the embodiment shown in fig. 3, comprise by reference at this, no longer repeat.
Then; In step S421; Equipment 2 obtains first greater than the residing coarse frequency value of the power spectral density power spectral density value of said adaptive threshold through the power spectral density value and the said adaptive threshold of power spectral density at the different frequency place that increases one by one by first frequency index step value compared.For example, it is k that equipment 2 is got said first frequency index step value, and wherein, k is greater than 1, and thus, equipment 2 is with frequency f
1, f
1+k... f
1+mkPower spectral density value S (the f at place
1), S (f
1+k) ... S (f
1+mk) respectively with said adaptive threshold S
ThRelatively, obtain for example, to be power spectral density value S (f first greater than the residing coarse frequency value of the power spectral density value of said adaptive threshold
1+mk) residing coarse frequency value f
1+mk
Then; In step S422; Equipment 2 is in the scheduled frequency range at center at said rough estimate frequency values, through power spectral density value and the said adaptive threshold of power spectral density at the different frequency place that increases one by one by second frequency index step value compared, obtains first greater than the residing fine frequency value of the power spectral density value of said adaptive threshold; Wherein, this second frequency index step value is less than this first frequency index step value.As a kind of optimal way, scheduled frequency range is:
Wherein, f
M_coarse=f
c-f
1+mk, B is the bandwidth that receives signal, and N is the number of frequencies that power spectral density comprises, and k is a first frequency index step value, f
1+mkBe the coarse frequency value.
For example, it is 1 that equipment 2 is got second frequency index step value, and thus, equipment 2 successively will
First frequency indices in the scope for example is j, second frequency indices, promptly j+1 ... n frequency indices, i.e. j+n, frequency value corresponding separately: f
j, f
J+1... f
J+n, pairing power spectral density value: S (f
j), S (f
J+1) ... S (f
J+n), respectively with adaptive threshold S
ThRelatively, obtain first greater than the residing fine frequency value of the power spectral density value of said adaptive threshold.For example, be S (f
J+n) residing frequency values f
J+n
Then, in step S43 ', equipment 2 is estimated said Doppler frequency shift according to fine frequency value that is obtained and said reception signal center frequency value.For example, the Doppler frequency shift
of equipment 2 estimations is:
Wherein, f
M_finerBe the fine frequency value, for example, f
M_finer=f
J+n
At last, in step S8, equipment 2 is carried out the Doppler shift compensation operation according to the Doppler frequency shift of being estimated.For example, equipment 2 moves according to the Doppler frequency shift of being estimated
and carries out the Doppler shift compensation operation.
Fig. 5 shows the flow chart in the method for carrying out the estimation of Doppler frequency displacement of wireless communication system of another aspect of the present invention.
Concrete, step S1 to S3, S41, S421, S422 and S43 ' describe in detail in the embodiment shown in fig. 4, comprise by reference at this, no longer repeat.
Then, in step S5, equipment 2 obtains the uplink downlink configuration information.For example, the uplink downlink configuration information that equipment 2 obtains is 0, and just the ratio of ascending-descending subframes is 3/1.It should be appreciated by those skilled in the art that the configuration information that equipment 2 obtains not is to exceed with said, in fact; For in the TD-LTE system, 7 kinds of different uplink-downlink configuration are arranged, wherein; The maximum rate of uplink and downlink subframe is 3/1, and the minimum rate of uplink and downlink subframe is 1/8.
Then, in step S6, equipment 2 is based on pre-defined rule, and confirms according to said uplink downlink configuration information whether the Doppler frequency shift of being estimated is available.Wherein, said pre-defined rule includes but not limited to: when the Doppler frequency shift of said estimation greater than adjustable factors β, then the Doppler frequency shift of this estimation can be used, wherein when uplink-downlink configuration be 0,1,3,6 o'clock, 150Hz＜β＜250Hz; When uplink-downlink configuration is 2,4,5 o'clock, 250Hz＜β＜350Hz.As a kind of optimal way, when uplink-downlink configuration is 0,1,3,6 o'clock, β=200Hz; When uplink-downlink configuration is 2,4,5 o'clock, β=300Hz.
For example; The configuration information that equipment 2 obtains is 0; Thus; Equipment 2 compares the Doppler frequency shift
of estimation with β=200Hz; If Doppler frequency shift
is greater than adjustable factors β; Then this Doppler frequency shift
is available, otherwise this Doppler frequency shift
is unavailable.
Then; In step S7; When definite this Doppler frequency shift
is unavailable; 2 pairs of said reception signals of equipment carry out interpolation processing, obtaining the signal after the interpolation, and with the signal after the said interpolation as said reception signal; Repeating step S3, S421, S422 and S43 ' obtain the Doppler frequency shift of new estimation thus.As a kind of optimal way, the channel data of 2 uplink times capable of using of equipment carries out the channel interpolation, to obtain the value of downlink transfer in the time, so that sampled point is even distribution.This is because when the rate travel of subscriber equipment 1 is very low; The non-time selectivity of channel between itself and the base station; Amplitude that also just means channel and produced and phase angle can think that be to change hardly on one or more symbol; So can carry out interpolation processing to received signal, improve the accuracy of many Preies frequency displacement of being estimated thus.
At last, in step S8, equipment 2 is carried out the Doppler shift compensation operation according to the Doppler frequency shift of being estimated.
Fig. 6 shows the equipment sketch map that carries out the estimation of Doppler frequency displacement at wireless communication system of one aspect of the invention.Wherein, subscriber equipment 1 be subscriber equipment 11, subscriber equipment 12 ... any one among the subscriber equipment 1K; Said equipment 2 comprises: first deriving means 21, frequency displacement estimating device 22.
Concrete, subscriber equipment 1 sends signal to equipment 2.
Then, first deriving means 21 receives the signal that sends from subscriber equipment 1.
Then, first deriving means 21 obtains the power spectral density information S (f) that receives signal.The mode that first deriving means 21 obtains the power spectral density information S (f) that receives signal includes but not limited to: 1) Classical Spectrum method of estimation; For example, period map method etc.; 2) modern spectral estimation method; For example, the parameter model spectrum is estimated and nonparametric model is composed estimation etc.
Then, frequency displacement estimating device 22 comes estimation of Doppler frequency displacement f according to said power spectral density information
m
Fig. 7 shows the equipment sketch map that carries out the estimation of Doppler frequency displacement at wireless communication system of another aspect of the present invention.Said equipment 2 comprises: first deriving means 21, frequency displacement estimating device 22.Wherein, said frequency displacement estimating device 22 comprises: second deriving means 221, the 3rd deriving means 222, and first calculation element 223.
Concrete, first deriving means 21 obtains the process of the power spectral density that receives signal and describes in detail in the embodiment shown in Figure 2, comprises by reference at this, no longer repeats.
Then, second deriving means 221 obtains an adaptive threshold according to said power spectral density information.For example, the adaptive threshold S that obtains according to power spectral density information of second deriving means 221
ThFor:
Wherein, S (0) expression frequency 0 place's power spectrum value, the value of S (1/T) expression power spectrum 1/T Hz place frequency spectrum, T is the up-downgoing change-over period, and α representes coefficient, and as a kind of optimal way, α equals 2.
It should be appreciated by those skilled in the art that above-mentioned adaptive threshold S
ThOnly just list, but not be used to limit the present invention, in fact, adaptive threshold S
ThCan be according to actual other different values of choosing.
Then, the 3rd deriving means 222 compares the power spectral density value and the said adaptive threshold at different frequency place in regular turn, obtains first the power spectral density power spectral density value frequency values of living in greater than said adaptive threshold.For example, the 3rd deriving means 222, in regular turn with the different frequency place, for example, f
1, f
2... f
N, wherein, f
1＜f
2＜...＜f
N, power spectral density value: S (f
1), S (f
2) ... S (f
N), respectively with adaptive threshold S
ThRelatively, obtain for example, to be power spectral density value S (f first greater than the power spectral density power spectral density value frequency values of living in of said adaptive threshold
i) frequency values f of living in
i
At last, first calculation element 223 is estimated said Doppler frequency shift according to frequency values that is obtained and said reception signal center frequency value.For example, first calculation element 223 is according to the frequency values f that is obtained
iDoppler frequency shift f with said reception signal center frequency value (the carrier frequency value of signal just) estimation
mFor:
f
m＝f
c-f
i。
Fig. 8 shows the equipment sketch map that carries out the estimation of Doppler frequency displacement at wireless communication system of another aspect of the present invention.Said equipment 2 comprises: first deriving means 21, frequency displacement estimating device 22 and frequency drift compensation device 26.Wherein, said frequency displacement estimating device 22 comprises: second deriving means 221, the 3rd deriving means 222, and first calculation element 223; Said the 3rd deriving means 222 further comprises: rough deriving means 2221 and meticulous deriving means 2222.
Concrete, first deriving means 21 and second deriving means 221 are described in detail in the embodiment shown in fig. 7, comprise by reference at this, no longer repeat.
Then; Rough deriving means 2221 obtains first greater than the residing coarse frequency value of the power spectral density power spectral density value of said adaptive threshold through the power spectral density value and the said adaptive threshold of power spectral density at the different frequency place that increases one by one by first frequency index step value compared.For example, it is k that rough deriving means 2221 is got said first frequency index step value, and wherein, k is greater than 1, and thus, rough deriving means 2221 is with frequency f
1, f
1+k... f
1+mkPower spectral density value S (the f at place
1), S (f
1+k) ... S (f
1+mk) respectively with said adaptive threshold S
ThRelatively, obtain for example, to be power spectral density value S (f first greater than the residing coarse frequency value of the power spectral density value of said adaptive threshold
1+mk) residing coarse frequency value f
1+mk
Then; Meticulous deriving means 2222 is in the scheduled frequency range at center at said rough estimate frequency values; Through power spectral density value and the said adaptive threshold of power spectral density at the different frequency place that increases one by one by second frequency index step value compared; Obtain first greater than the residing fine frequency value of the power spectral density value of said adaptive threshold, wherein, this second frequency index step value is less than this first frequency index step value.As a kind of optimal way, scheduled frequency range is:
Wherein, f
M_coarse=f
c-f
1+mk, B is the bandwidth that receives signal, and N is the number of frequencies that power spectral density comprises, and k is a first frequency index step value, f
1+mkBe the coarse frequency value.
For example, it is 1 that meticulous deriving means 2222 is got second frequency index step value, and thus, meticulous deriving means 2222 successively will
First frequency indices in the scope for example is j, second frequency indices, promptly j+1 ... n frequency indices, i.e. j+n, frequency value corresponding separately: f
j, f
J+1... f
J+n, pairing power spectral density value: S (f
j), S (f
J+1) ... S (f
J+n), respectively with adaptive threshold S
ThRelatively, obtain first greater than the residing fine frequency value of the power spectral density value of said adaptive threshold.For example, be S (f
J+n) residing frequency values f
J+n
Then, first calculation element 223 is estimated said Doppler frequency shift according to fine frequency value that is obtained and said reception signal center frequency value.For example, the Doppler frequency shift
of first calculation element, 223 estimations is:
Wherein, f
M_finerBe the fine frequency value, for example, f
M_finer=f
J+nAt last, frequency drift compensation device 26 is carried out the Doppler shift compensation operation according to the Doppler frequency shift of being estimated.For example, frequency drift compensation device 26 moves according to the Doppler frequency shift of being estimated
and carries out the Doppler shift compensation operation.
Fig. 9 shows the equipment sketch map that carries out the estimation of Doppler frequency displacement at wireless communication system of another aspect of the present invention.Said equipment 2 comprises: first deriving means 21, frequency displacement estimating device 22, the 4th deriving means 23, judgment means 24, interpolating apparatus 25, and frequency drift compensation device 26.Wherein, said frequency displacement estimating device 22 comprises: second deriving means 221, the 3rd deriving means 222, and first calculation element 223; Said the 3rd deriving means 222 further comprises: rough deriving means 2221 and meticulous deriving means 2222.
Concrete; First deriving means 21, second deriving means 221, rough deriving means 2221, meticulous deriving means 2222, and first calculation element 223 describe in detail in the embodiment shown in fig. 8; Comprise by reference at this, no longer repeat.
Then, the 4th deriving means 23 obtains the uplink downlink configuration information.For example, the uplink downlink configuration information that the 4th deriving means 23 obtains is 0, and just the ratio of ascending-descending subframes is 3/1.It should be appreciated by those skilled in the art that the configuration information that the 4th deriving means 23 obtains not is to exceed with said, in fact; For in the TD-LTE system, 7 kinds of different uplink-downlink configuration are arranged, wherein; The maximum rate of uplink and downlink subframe is 3/1, the minimum rate 1/8 of uplink and downlink subframe.
Then, judgment means 24 is based on pre-defined rule, and confirms according to said uplink downlink configuration information whether the Doppler frequency shift that said first calculation element 223 estimated is available.Wherein, said pre-defined rule includes but not limited to: when the Doppler frequency shift of said estimation greater than adjustable factors β, then the Doppler frequency shift of this estimation can be used, wherein when uplink-downlink configuration be 0,1,3,6 o'clock, 150Hz＜β＜250Hz; When uplink-downlink configuration is 2,4,5 o'clock, 250Hz＜β＜350Hz.As a kind of optimal way, when uplink-downlink configuration is 0,1,3,6 o'clock, β=200Hz; When uplink-downlink configuration is 2,4,5 o'clock, β=300Hz.
For example; The configuration information that the 4th deriving means 23 obtains is 0; Thus; Judgment means 24 compares the Doppler frequency shift
of said first calculation element 223 estimations with β=200Hz; If Doppler frequency shift
is greater than adjustable factors β; Then this Doppler frequency shift
is available, otherwise this Doppler frequency shift
is unavailable.
Then; When definite this Doppler frequency shift
is unavailable; 25 pairs of said reception signals of interpolating apparatus carry out interpolation processing; Obtaining the signal after the interpolation, and with the signal after the said interpolation as said reception signal, offer first deriving means 21; Obtain the power spectral density information of the signal after the said interpolation by first deriving means 21; Then, obtain corresponding coarse frequency value by rough deriving means 2221 again after, offer meticulous deriving means 2222; Then, obtain the fine frequency value by meticulous deriving means 2222 after, offer said first calculation element 223, so that obtain the Doppler frequency shift of new estimation.As a kind of optimal way, the channel data of 25 uplink times capable of using of interpolating apparatus carries out the channel interpolation, to obtain the value of downlink transfer in the time, so that sampled point is even distribution.This is because when the rate travel of subscriber equipment 1 is very low; The non-time selectivity of channel between itself and the base station; Amplitude that also just means channel and produced and phase angle can think that be to change hardly on one or more symbol; So can carry out interpolation processing to received signal, improve the accuracy of many Preies frequency displacement of being estimated thus.
At last, frequency drift compensation device 26 is carried out the Doppler shift compensation operation according to the Doppler frequency shift of being estimated.
Below superior function of the present invention is explained in emulation.
Subscriber equipment to be placed in the vehicle is that example is carried out emulation.Wherein, auto model adopts EVA model, vehicle translational speed (moving user equipment just) v=0～360km/h, carrier frequency f
c=2.6GHz, maximum Doppler frequency shift f
m=0～866.67Hz, SNR=20dB.
Three kinds are mainly used in the algorithm performance of estimating maximum doppler frequency shown in Figure 10.Wherein, LCR and ZCR algorithm arrive under the situation of 250Hz at 100Hz at Doppler frequency shift, obtain satisfied performance; And when Doppler frequency shift became big gradually, LCR and the distortion of ZCR algorithm were very serious.Yet scheme of the present invention (being the PSD method) still can on the numerical value of Doppler frequency shift, obtain satisfied performance, and the relative error of PSD method is within 6%.
Figure 11 is illustrated in that uplink-downlink configuration is respectively 0,1 in the TD-LTE system, 6 o'clock performance.The relative error of configuration 0 (this moment, the ratio of ascending-descending subframes was 3/1) is in 6%; The relative error of configuration 6 (this moment, the ascending-descending subframes ratio was 5/3) is in 7%; The relative error of configuration 1 (this moment, the ascending-descending subframes ratio was 1/1) is in 4%.Visible by figure, when ratio decline time error improves gradually.
To those skilled in the art, obviously the invention is not restricted to the details of above-mentioned example embodiment, and under the situation that does not deviate from spirit of the present invention or essential characteristic, can realize the present invention with other concrete form.Therefore; No matter from which point; All should regard embodiment as exemplary; And be nonrestrictive, scope of the present invention is limited accompanying claims rather than above-mentioned explanation, therefore is intended to the implication of the equivalents that drops on claim and all changes in the scope are included in the present invention.Should any Reference numeral in the claim be regarded as limit related claim.In addition, obviously other unit or step do not got rid of in " comprising " speech, and odd number is not got rid of plural number.A plurality of unit of stating in system's claim or device also can be realized through software or hardware by a unit or device.The first, the second word such as grade is used for representing title, and does not represent any specific order.
Claims (14)
1. method of carrying out the estimation of Doppler frequency displacement at wireless communication system, wherein, this method may further comprise the steps:
A obtains the power spectral density information that receives signal in the up link;
B comes the estimation of Doppler frequency displacement according to said power spectral density information.
2. method according to claim 1, wherein, said step b also comprises:
-obtain an adaptive threshold according to said power spectral density information;
Wherein, said step b also comprises:
B1 compares the power spectral density value and the said adaptive threshold at different frequency place in regular turn, obtains first greater than the power spectral density value of said adaptive threshold frequency values of living in;
B2 estimates said Doppler frequency shift according to frequency values that is obtained and said reception signal center frequency value.
3. method according to claim 2, wherein, said step b1 also comprises:
-through power spectral density value and the said adaptive threshold of power spectral density at the different frequency place that increases one by one by first frequency index step value compared, obtain first greater than the residing coarse frequency value of the power spectral density value of said adaptive threshold;
-be in the scheduled frequency range at center at said rough estimate frequency values; Through power spectral density value and the said adaptive threshold of power spectral density at the different frequency place that increases one by one by second frequency index step value compared; Obtain first greater than the residing fine frequency value of the power spectral density value of said adaptive threshold; Wherein, this second frequency index step value is less than this first frequency index step value;
Wherein, said step b2 also comprises:
-estimate said Doppler frequency shift according to fine frequency value that is obtained and said reception signal center frequency value.
4. according to claim 2 or 3 described methods, wherein, also comprise:
-obtain the uplink downlink configuration information;
Wherein, also comprise:
-based on pre-defined rule, and confirm according to said uplink downlink configuration information whether the Doppler frequency shift of being estimated is available;
-when the Doppler frequency shift of confirming to be estimated is unavailable, said reception signal is carried out interpolation processing, obtaining the signal after the interpolation, and with the signal after the said interpolation as said reception signal in order to repeat above-mentioned steps a, b1, b2.
5. method according to claim 4, wherein, said pre-defined rule comprises:
-when the Doppler frequency shift of said estimation greater than adjustable factors β, then the Doppler frequency shift of this estimation can be used, wherein when uplink-downlink configuration be 0,1,3,6 o'clock, 150Hz＜β＜250Hz; When uplink-downlink configuration is 2,4,5 o'clock, 250Hz＜β＜350Hz.
6. according to each described method in the claim 1 to 5, wherein, also comprise:
-carry out the Doppler shift compensation operation according to the Doppler frequency shift of being estimated.
7. according to said each the method for claim 1 to 6, wherein, said wireless communication system comprises 3G, LTE or WiMAX system.
8. equipment that carries out the estimation of Doppler frequency displacement at wireless communication system, wherein, this equipment comprises:
First deriving means is used for obtaining the power spectral density information that up link receives signal;
The frequency displacement estimating device is used for coming the estimation of Doppler frequency displacement according to said power spectral density information.
9. equipment according to claim 8, wherein, said frequency displacement estimating device also comprises:
Second deriving means is used for obtaining an adaptive threshold according to said power spectral density information;
The 3rd deriving means is used in regular turn the power spectral density value and the said adaptive threshold at different frequency place are compared, and obtains first the residing frequency values of power spectral density power spectral density value greater than said adaptive threshold;
First calculation element is used for estimating said Doppler frequency shift according to frequency values that is obtained and said reception signal center frequency value.
10. equipment according to claim 9, wherein, said the 3rd deriving means also comprises:
Rough deriving means; Be used for obtaining first greater than the residing coarse frequency value of the power spectral density value of said adaptive threshold through the power spectral density value and the said adaptive threshold of power spectral density at the different frequency place that increases one by one by first frequency index step value compared;
Meticulous deriving means; Being used at said rough estimate frequency values is in the scheduled frequency range at center; Through power spectral density value and the said adaptive threshold of power spectral density at the different frequency place that increases one by one by second frequency index step value compared; Obtain first greater than the residing fine frequency value of the power spectral density value of said adaptive threshold, wherein, this second frequency index step value is less than this first frequency index step value;
Wherein, said first calculation element also is used for estimating said Doppler frequency shift according to fine frequency value that is obtained and said reception signal center frequency value.
11., wherein, also comprise according to claim 9 or 10 described equipment:
The 4th deriving means is used to obtain the uplink downlink configuration information;
Wherein, also comprise:
Judgment means is used for based on pre-defined rule, and confirms according to said uplink downlink configuration information whether the Doppler frequency shift of being estimated is available;
Interpolating apparatus is used for when confirming that the Doppler frequency shift of being estimated is unavailable, said reception signal being carried out interpolation processing, with the signal after the acquisition interpolation;
Wherein,
Said first deriving means is used to obtain the power spectral density information of the signal after the said interpolation, and offers said second and third deriving means.
12. equipment according to claim 11, wherein, said pre-defined rule comprises:
-when the Doppler frequency shift of said estimation greater than adjustable factors β, then the Doppler frequency shift of this estimation can be used, wherein when uplink-downlink configuration be 0,1,3,6 o'clock, 150Hz＜β＜250Hz; When uplink-downlink configuration is 2,4,5 o'clock, 250Hz＜β＜350Hz.
13. each described equipment in 12 according to Claim 8 wherein, also comprises:
The frequency drift compensation device is used for carrying out the Doppler shift compensation operation according to the Doppler frequency shift of being estimated.
14. to 13 said each equipment, wherein, said wireless communication system comprises 3G, LTE or WiMAX system according to Claim 8, said equipment comprises base station or NodeB, the network controller of said Target cell.
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| CN104580055A (en) * | 2014-12-10 | 2015-04-29 | 华南理工大学 | Doppler estimation method capable of determining interval for searching based on construction of target derived function |
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