CN102082744B - Method and device for estimating frequency deviation based on pilot frequency and data - Google Patents

Abstract

The invention discloses a method for estimating frequency deviation based on pilot frequency and data. The method comprises: acquiring a frequency domain channel estimated value of a pilot frequency bit of an object user; calculating the phase of pilot frequency channel estimation; selecting a data symbol according to the phase of the pilot frequency channel estimation, and acquiring the phase information caused by frequency deviation according to the data symbol; acquiring a residual phase difference according to the phase information and the pilot frequency signal channel estimation; and acquiring a frequency deviation value according to the residual phase difference. The invention also discloses a frequency deviation estimation device based on pilot frequency and data. According to the invention, the performance frequency deviation estimated capacity of a receiver can be improved, the relative frequency deviation between a base station and a terminal can be estimated effectively, the interference caused by sub carrier wave orthogonality damage of an OFDM (orthogonal frequency division multiplexing) system is reduced, the estimation and compensation range of the frequency deviation by the receiver is improved, especially when large frequency deviation exists in a high-speed moving environment link, the frequency deviation value exists in a system can be estimated more accurately, and a reliable guarantee is provided for the communication service quality.

Description

A kind of frequency deviation estimating method and device based on pilot tone and data

Technical field

The present invention relates to wireless communication technology field, particularly relate to a kind of frequency deviation estimating method based on pilot tone and data and device.

Background technology

LTE (Long Term Evolution, Long Term Evolution) project is 3GPP (ThirdGeneration Partnership Projects over the past two years, third generation partnership project) the new technology development project of the maximum of Qi Donging, it improves and has strengthened the aerial access technology of 3G (Third Generation, 3G (Third Generation) Moblie technology).Compare with 3G, LTE has more technical advantage, is embodied in higher user data rate, grouping transmission, the improvement that reduces system delay, power system capacity and covering and the aspects such as reduction of operation cost.

The LTE down link adopts OFDM (Orthogonal Furequency Division Multiplexity, OFDM) technology, OFDM has characteristics such as availability of frequency spectrum height, anti-multipath interference, and ofdm system can be resisted the influence that wireless channel brings effectively.LTE ul transmissions scheme adopts SC-FDMA (the Single Carrier Furequency Division Multiplexity of band Cyclic Prefix, single carrier frequency division is multiplexing), in the SC-FDMA transmission plan of up employing band Cyclic Prefix, use DFT (DiscreteFourier Transformation, discrete Fourier transform (DFT)) obtains frequency-region signal, insert nil symbol then and carry out frequency spectrum shift, signal after moving is again by IFFT (Inverse Fast Fourier Transformation, contrary fast fourier transform), can reduce the peak-to-average power ratio of launch terminal.

For multicarrier system, the skew of carrier frequency can cause producing between the subchannel to be disturbed.Have a plurality of orthogonal sub-carriers in the ofdm system, output signal is the stack of a plurality of sub-channel signals, because subchannel covers mutually, this just has higher requirement to the orthogonality of intercarrier.

Because the movement of terminal can produce Doppler frequency shift between base station and terminal, in mobile communication system, particularly under the high speed scene, this frequency displacement is especially obvious.Doppler frequency shift will make and produce frequency error between the Receiver And Transmitter, cause receiving signal and be offset in frequency domain, introduce inter-carrier interference, make the bit error rate performance of system worsen.

The size of Doppler frequency shift is relevant with the speed of related movement size, and the relation between them is:

$f_d=-\frac{f_0}{C}\×v\×\cos \mathrm{\θ}$

Wherein, θ is the angle between terminal moving direction and the signal propagation direction; V is the terminal movement velocity; C is propagation velocity of electromagnetic wave; f ₀Be carrier frequency.

The LTE system is for portable terminal, guarantee mobile subscriber's system performance optimum of 15km/h and following speed, and can provide high performance service to the mobile subscriber of 15～120km/h, and keep 120～350km/h mobile subscriber's service, be higher than the 350km/h mobile subscriber and do not fall net.In this velocity interval, Doppler frequency shift surpasses 400Hz, and base station and terminal must support enough compensate of frequency deviation technology could satisfy operation quality requirement.

For receiver, estimate and transmitter between frequency error and to finish correction of frequency errors be the function that receiver must be finished.Terminal receives f _dFrequency displacement, send upward signal after the terminal locking downstream signal frequencies, up reception will have 2*f _dFrequency displacement.

Frequency deviation schematic diagram in existing a kind of terminal moving process as shown in Figure 1, the direction of relative movement of terminal and base station is different, can produce positive and negative different frequency deviation, establishes f ₀Be the tranmitting frequency of base station, when terminal to away from the motion of the direction of base station the time, can produce negative frequency deviation-f _d, the frequency that terminal receives is f ₀-f _d, the frequency that the base station receives is f ₀-2*f _dWhen terminal is moved to the direction of close base station, can produce positive frequency deviation f _d, the frequency that terminal receives is f ₀+ f _d, the frequency that the base station receives is f ₀+ 2*f _dWhen terminal is moved between two base stations, when driving towards another base station from a base station, terminal can frequency of occurrences saltus step, from frequency f ₀-f _dBe transferred to frequency f ₀+ f _d, terminal will have 2*f _dFrequency hopping.2*f _dNo matter for base station receiver, or terminal receiver all will be a no small challenge, and excessive frequency offset can cause communication quality to descend, and can cause service disruption in the time of serious, especially under high-speed mobile environment.

If can not correctly estimate frequency deviation and compensate, systematic function will reduce greatly so, especially when frequency deviation is big (when the counterpart terminal movement velocity is higher), using pilot tone to do frequency deviation in the prior art estimates, the frequency deviation region that can estimate is little, the complexity height, when there was big frequency deviation in system, anti-noise ability descended to some extent.

Summary of the invention

The problem to be solved in the present invention provides a kind of frequency deviation estimating method based on pilot tone and data and device, uses pilot tone to do the frequency deviation estimation in the prior art to overcome, and the frequency deviation region of estimation is little, the defective that complexity is high.

For achieving the above object, technical scheme of the present invention provides a kind of frequency deviation estimating method based on pilot tone and data, said method comprising the steps of: the pilot bit frequency domain channel estimated value of obtaining the targeted customer; Calculate the phase place of pilot channel estimation; Phase place according to described pilot channel estimation is selected data symbol, and obtains the phase information that frequency deviation causes according to described data symbol; Obtain the last phase potential difference according to the phase place of described phase information and pilot channel estimation; Obtain frequency deviation value according to described last phase potential difference.

Further, in the step of the described pilot bit frequency domain channel estimated value of obtaining the targeted customer, specifically comprise: according to formula $H_1^{\left(m\right)}\left(k\right)=\frac{Y_1^{\left(m\right)}\left(k\right)}{X^m\left(k\right)},$ 1≤k≤M and $H_2^{\left(m\right)}\left(k\right)=\frac{Y_2^{\left(m\right)}\left(k\right)}{X^m\left(k\right)},$ 1≤k≤M obtains targeted customer's pilot bit frequency domain channel estimated value, wherein H ₁ ^(m)(k) be the channel estimation value of pilot tone 1, H ₂ ^(m)(k) be the channel estimation value of pilot tone 2, Y ₁ ^(m)(k) be the frequency domain receiving sequence of pilot tone 1, Y ₂ ^(m)(k) be the frequency domain receiving sequence of pilot tone 2, X ^(m)(k) be local pilot tone sign indicating number, length is M, and m is the user.

Further, in the step of the phase place of described calculating pilot channel estimation, specifically comprise: according to formula

${\mathrm{\φ}}_{h\_\mathrm{slot}\_i}^{\left(m\right)}=\frac{1}{M}\underset{k=1}{\overset{M}{\mathrm{\Σ}}}\∠H_{h\_\mathrm{slot}\_i}^{\left(m\right)}\left(k\right)-n\·\frac{\mathrm{\π}}{2}$

Calculate the phase of pilot channel estimation _H-slot-i ^(m), ∠ is for asking the computing of argument of a complex number main value, H _H-slot-i ^(m)(k) be pilot bit frequency domain channel estimated value, h_slot_i=1 or 2, n ∈ integer makes ${\mathrm{\φ}}_{h\_\mathrm{slot}\_i}\∈(-\frac{\mathrm{\π}}{2},\frac{\mathrm{\π}}{2}).$

Further, described phase place according to pilot channel estimation selects data symbol to be specially: when the phase place of described pilot channel estimation greater than 0 the time, select the data symbol on the described pilot bit left side; When the phase place of described pilot channel estimation is less than or equal to 0, select the data symbol on described pilot bit the right.

Further, when the phase place of described pilot channel estimation greater than 0 the time, select the adjacent data symbol in the described pilot bit left side; When the phase place of described pilot channel estimation is less than or equal to 0, select the adjacent data symbol in described pilot bit the right.

Further, describedly obtain the phase information that frequency deviation causes and be specially: the data symbol of described selection is corresponded to the territory of modulation symbol, rectification, and declare data firmly, the data after declaring firmly are modulated to symbol again; The conjugation that multiply by the symbol after the judgement with unsentenced symbol obtains a complex values, and described complex values is asked phase place, obtains the residual phase of data symbol.

Further, in the described step of obtaining the last phase potential difference, specifically comprise: according to formula

Last phase potential difference Δ φ is obtained in calculating ^(m), φ wherein _H-slot-i ^(m)Be the phase place of pilot channel estimation,

Be the residual phase of data symbol, i is the data symbol sequence number, and m is the user.

Further, the described step of obtaining frequency deviation value according to phase difference specifically comprises: according to formula $f=\frac{\mathrm{\Δ}{\mathrm{\φ}}^{\left(m\right)}}{2\mathrm{\π}\×0.5\×{10}^{-3}/7\×x}$ Calculate frequency deviation value f, wherein Δ φ ^(m)Be the last phase potential difference, x is the data symbol number at interval between pilot tone and the selected data symbol.

Further, after the described step of obtaining frequency deviation value according to phase difference, also comprise: judge according to described frequency deviation value and select branch, and obtain the frequency deviation initial value corresponding with described branch; Frequency deviation initial value according to described branch correspondence carries out the frequency deviation estimation in conjunction with pilot tone.

Further, carry out in conjunction with pilot tone specifically comprising: with the pilot bit frequency domain channel estimated value H of user m in the step of frequency deviation estimation at described frequency deviation initial value according to branch's correspondence ₁ ^(m)(k), H ₂ ^(m)(k) be divided into the Q section, in every section, carry out frequency domain smoothing, and to continuous N _SmoothingPilot bit frequency domain channel estimated value on=M/Q subcarrier is averaging, and obtains mean value H _{1, s} ^(m)And H _{2, s} ^(m)According to formula

$\left\{\begin{array}{c}{\mathrm{\Δ\Δf}}_{s,\mathrm{ka}}=\frac{\∠\left({\stackrel{\‾}{H}}_{2,s}^{\left(m\right)}\right)/\left({\stackrel{\‾}{H}}_{1,s}^{\left(m\right)}\right)}{2\mathrm{\π}\·t}-\mathrm{\Δ}{f}_0+l\×2000\\ {\mathrm{\Δ\Δf}}_{\mathrm{ka}}=\frac{1}{Q}\underset{s}{\overset{Q}{\mathrm{\Σ}}}{\mathrm{\Δ\Δf}}_{s,\mathrm{ka}}\\ {\mathrm{\Δf}}_{\mathrm{ka}}={\mathrm{\Δf}}_0+{\mathrm{\Δ\Δf}}_{\mathrm{ka}}\end{array}\right.$

Obtain frequency deviation and estimate Δ f _Ka, wherein ∠ is for asking the computing of argument of a complex number main value, and t is at interval number between two subcarriers that calculate phase differences, Δ f ₀Be the frequency deviation initial value corresponding with branch, l is for making Δ Δ f _{S, ka}The integer of ∈ (1000,1000), s is the sequence number of group, Δ Δ f _{S, ka}With Δ Δ f _KaBe middle frequency deviation value.

Further, at the described mean value H that obtains _{1, s} ^(m)And H _{2, s} ^(m)Step in, specifically comprise: according to formula

${\stackrel{\‾}{H}}_{1,s}^{\left(m\right)}=\frac{1}{N_{\mathrm{smooting}}}\underset{j=1}{\overset{N_{\mathrm{smoothing}}}{\mathrm{\Σ}}}{H}_1^{\left(m\right)}((s-1)\×N_{\mathrm{smoothing}}+j),$ 1≤s≤Q, 1≤j≤N _SmoothingWith

${\stackrel{\‾}{H}}_{2,s}^{\left(m\right)}=\frac{1}{N_{\mathrm{smooting}}}\underset{j=1}{\overset{N_{\mathrm{smoothing}}}{\mathrm{\Σ}}}{H}_2^{\left(m\right)}((s-1)\×N_{\mathrm{smoothing}}+j),$ 1≤s≤Q，1≤j≤N _smoothing

Obtain mean value H _{1, s} ^(m)And H _{2, s} ^(m), wherein s is the sequence number of group, the sequence number of element during j is every group.

Technical scheme of the present invention also provides a kind of frequency deviation estimation device based on pilot tone and data, and described device comprises: pilot bit frequency domain channel estimated value acquiring unit, for the pilot bit frequency domain channel estimated value of obtaining the targeted customer; The phase place acquiring unit of pilot channel estimation is for the phase place of calculating pilot channel estimation; The phase information acquiring unit is used for selecting data symbol according to the phase place of described pilot channel estimation, and obtains the phase information that frequency deviation causes according to described data symbol; Last phase potential difference acquiring unit is used for the phase place according to described phase information and pilot channel estimation, obtains the last phase potential difference; The frequency deviation value acquiring unit is used for obtaining frequency deviation value according to described last phase potential difference.

Further, described device also comprises: frequency deviation initial value acquiring unit, and the frequency deviation value that is used for obtaining according to described frequency deviation value acquiring unit is judged selection branch, and obtains the frequency deviation initial value corresponding with described branch; Frequency deviation estimating unit is used for carrying out the frequency deviation estimation according to the frequency deviation initial value of described branch correspondence in conjunction with pilot tone.

Compared with prior art, beneficial effect of the present invention is as follows:

The present invention estimates frequency deviation initial value scope according to the phase difference between pilot tone and the OFDM data symbol, estimate frequency deviation value with the frequency deviation initial value scope that estimates in conjunction with pilot tone again, thereby improve receiver performance frequency deviation estimated capacity, can estimate the relative frequency deviation between base station and the terminal effectively, reduce ofdm system owing to sub-carrier orthogonality being destroyed the interference that brings, improve receiver to estimation and the compensation range of frequency deviation, when especially having big frequency deviation in the high-speed mobile environment link, the frequency deviation value that exists in the estimating system more accurately is for telecommunication service quality provides reliable guarantee.

Description of drawings

Fig. 1 is the frequency deviation schematic diagram in a kind of terminal moving process of prior art;

Fig. 2 is the flow chart of a kind of frequency deviation estimating method based on pilot tone and data of the embodiment of the invention one;

Fig. 3 is the flow chart of a kind of frequency deviation estimating method based on pilot tone and data of the embodiment of the invention two;

Fig. 4 is a kind of frequency deviation branch schematic diagram of the embodiment of the invention;

Fig. 5 is the structural representation of a kind of frequency deviation estimation device based on pilot tone and data of the embodiment of the invention three.

Embodiment

Below in conjunction with drawings and Examples, the specific embodiment of the present invention is described in further detail.Following examples are used for explanation the present invention, but are not used for limiting the scope of the invention.

The invention provides a kind of frequency deviation estimating method based on pilot tone and data, said method comprising the steps of: the pilot bit frequency domain channel estimated value of obtaining the targeted customer; Calculate the phase place of pilot channel estimation; Phase place according to described pilot channel estimation is selected data symbol, and obtains the phase information that frequency deviation causes according to described data symbol; Obtain the last phase potential difference according to the phase place of described phase information and pilot channel estimation; Obtain frequency deviation value according to described last phase potential difference.

In the step of the described pilot bit frequency domain channel estimated value of obtaining the targeted customer, specifically comprise: according to formula $H_1^{\left(m\right)}\left(k\right)=\frac{Y_1^{\left(m\right)}\left(k\right)}{X^m\left(k\right)},$ 1≤k≤M and $H_2^{\left(m\right)}\left(k\right)=\frac{Y_2^{\left(m\right)}\left(k\right)}{X^m\left(k\right)},$ 1≤k≤M obtains targeted customer's pilot bit frequency domain channel estimated value, wherein H ₁ ^(m)(k) be the channel estimation value of pilot tone 1, H ₂ ^(m)(k) be the channel estimation value of pilot tone 2, Y ₁ ^(m)(k) be the frequency domain receiving sequence of pilot tone 1, Y ₂ ^(m)(k) be the frequency domain receiving sequence of pilot tone 2, X ^(m)(k) be local pilot tone sign indicating number, length is M, and m is the user.

In the step of the phase place of described calculating pilot channel estimation, specifically comprise: according to formula

${\mathrm{\φ}}_{h\_\mathrm{slot}\_i}^{\left(m\right)}=\frac{1}{M}\underset{k=1}{\overset{M}{\mathrm{\Σ}}}\∠H_{h\_\mathrm{slot}\_i}^{\left(m\right)}\left(k\right)-n\·\frac{\mathrm{\π}}{2}$

Calculate the phase of pilot channel estimation _H-slot-i ^(m), ∠ is for asking the computing of argument of a complex number main value, H _H-slot-i ^(m)(k) be pilot bit frequency domain channel estimated value, h_slot_i=1 or 2, n ∈ integer makes ${\mathrm{\φ}}_{h\_\mathrm{slot}\_i}\∈(-\frac{\mathrm{\π}}{2},\frac{\mathrm{\π}}{2}).$

Described phase place according to pilot channel estimation selects data symbol to be specially: when the phase place of described pilot channel estimation greater than 0 the time, select the data symbol on the described pilot bit left side; When the phase place of described pilot channel estimation is less than or equal to 0, select the data symbol on described pilot bit the right.Preferably, when the phase place of described pilot channel estimation greater than 0 the time, select the adjacent data symbol in the described pilot bit left side; When the phase place of described pilot channel estimation is less than or equal to 0, select the adjacent data symbol in described pilot bit the right.

Describedly obtain the phase information that frequency deviation causes and be specially: the data symbol of described selection is corresponded to the territory of modulation symbol, rectification, and declare data firmly, the data after declaring firmly are modulated to symbol again; The conjugation that multiply by the symbol after the judgement with unsentenced symbol obtains a complex values, and described complex values is asked phase place, obtains the residual phase of data symbol.

In the described step of obtaining the last phase potential difference, specifically comprise: according to formula

Last phase potential difference Δ φ is obtained in calculating ^(m), φ wherein _H-slot-i ^(m)Be the phase place of pilot channel estimation,

Be the residual phase of data symbol, i is the data symbol sequence number, and m is the user.

The described step of obtaining frequency deviation value according to phase difference specifically comprises: according to formula $f=\frac{\mathrm{\Δ}{\mathrm{\φ}}^{\left(m\right)}}{2\mathrm{\π}\×0.5\×{10}^{-3}/7\×x}$ Calculate frequency deviation value f, wherein Δ φ ^(m)Be the last phase potential difference, x is the data symbol number at interval between pilot tone and the selected data symbol.

After the described step of obtaining frequency deviation value according to phase difference, also comprise: judge according to described frequency deviation value and select branch, and obtain the frequency deviation initial value corresponding with described branch; Frequency deviation initial value according to described branch correspondence carries out the frequency deviation estimation in conjunction with pilot tone.

Carry out in conjunction with pilot tone specifically comprising: with the pilot bit frequency domain channel estimated value H of user m in the step of frequency deviation estimation at described frequency deviation initial value according to branch's correspondence ₁ ^(m)(k), H ₂ ^(m)(k) be divided into the Q section, in every section, carry out frequency domain smoothing, and to continuous N _SmoothingPilot bit frequency domain channel estimated value on=M/Q subcarrier is averaging, and obtains mean value H _{1, s} ^(m)And H _{2, s} ^(m)According to formula

$\left\{\begin{array}{c}{\mathrm{\Δ\Δf}}_{s,\mathrm{ka}}=\frac{\∠\left({\stackrel{\‾}{H}}_{2,s}^{\left(m\right)}\right)/\left({\stackrel{\‾}{H}}_{1,s}^{\left(m\right)}\right)}{2\mathrm{\π}\·t}-\mathrm{\Δ}{f}_0+l\×2000\\ {\mathrm{\Δ\Δf}}_{\mathrm{ka}}=\frac{1}{Q}\underset{s}{\overset{Q}{\mathrm{\Σ}}}{\mathrm{\Δ\Δf}}_{s,\mathrm{ka}}\\ {\mathrm{\Δf}}_{\mathrm{ka}}={\mathrm{\Δf}}_0+{\mathrm{\Δ\Δf}}_{\mathrm{ka}}\end{array}\right.$

Obtain frequency deviation and estimate Δ f _Ka, wherein ∠ is for asking the computing of argument of a complex number main value, and t is at interval number between two subcarriers that calculate phase differences, Δ f ₀Be the frequency deviation initial value corresponding with branch, l is for making Δ Δ f _{S, ka}The integer of ∈ (1000,1000), s is the sequence number of group, Δ Δ f _{S, ka}With the Δ Δ _FkaBe middle frequency deviation value.

At the described mean value H that obtains _{1, s} ^(m)And H _{2, s} ^(m)Step in, specifically comprise: according to formula

${\stackrel{\‾}{H}}_{1,s}^{\left(m\right)}=\frac{1}{N_{\mathrm{smooting}}}\underset{j=1}{\overset{N_{\mathrm{smoothing}}}{\mathrm{\Σ}}}{H}_1^{\left(m\right)}((s-1)\×N_{\mathrm{smoothing}}+j),$ 1≤s≤Q, 1≤j≤N _SmoothingWith

${\stackrel{\‾}{H}}_{2,s}^{\left(m\right)}=\frac{1}{N_{\mathrm{smooting}}}\underset{j=1}{\overset{N_{\mathrm{smoothing}}}{\mathrm{\Σ}}}{H}_2^{\left(m\right)}((s-1)\×N_{\mathrm{smoothing}}+j),$ 1≤s≤Q，1≤j≤N _smoothing

Obtain mean value H _{1, s} ^(m)And H _{2, s} ^(m), wherein s is the sequence number of group, the sequence number of element during j is every group.

Embodiment one

A kind of frequency deviation estimating method based on pilot tone and data of the embodiment of the invention may further comprise the steps as shown in Figure 2:

Step s201 obtains targeted customer's pilot bit frequency domain channel estimated value.In the present embodiment, according to following formula

$H_1^{\left(m\right)}\left(k\right)=\frac{Y_1^{\left(m\right)}\left(k\right)}{X^m\left(k\right)},$ 1≤k≤M and

$H_2^{\left(m\right)}\left(k\right)=\frac{Y_2^{\left(m\right)}\left(k\right)}{X^m\left(k\right)},$ 1≤k≤M

Obtain the pilot bit frequency domain channel estimated value of user m, wherein H ₁ ^(m)(k) be the channel estimation value of pilot tone 1, H ₂ ^(m)(k) be the channel estimation value of pilot tone 2, Y ₁ ^(m)(k) be the frequency domain receiving sequence of pilot tone 1, Y ₂ ^(m)(k) be the frequency domain receiving sequence of pilot tone 2, X ^(m)(k) be local pilot tone sign indicating number, length is M, φ ₁And φ ₂The t that comprises pilot tone 1 correspondence respectively ₁T with pilot tone 2 correspondences ₂Channel phase characteristic and frequency deviation phase information constantly.

Step s202, the phase place of calculating pilot channel estimation.In the present embodiment, according to formula

${\mathrm{\φ}}_{h\_\mathrm{slot}\_i}^{\left(m\right)}=\frac{1}{M}\underset{k=1}{\overset{M}{\mathrm{\Σ}}}\∠H_{h\_\mathrm{slot}\_i}^{\left(m\right)}\left(k\right)-n\·\frac{\mathrm{\π}}{2}$

Calculate the phase of pilot channel estimation _H-slot-i ^(m), wherein, ∠ is for asking the computing of argument of a complex number main value, H _H-slot-i ^(m)(k) be pilot bit frequency domain channel estimated value, h_slot_i=1 or 2, n ∈ integer makes

${\mathrm{\φ}}_{h\_\mathrm{slot}\_i}\∈(-\frac{\mathrm{\π}}{2},\frac{\mathrm{\π}}{2}).$

Step s203 selects data symbol according to the phase place of described pilot channel estimation, and obtains the phase information that frequency deviation causes according to described data symbol.In the present embodiment, when the phase place of described pilot channel estimation greater than 0 the time, select the data symbol on the described pilot bit left side to carry out frequency deviation and estimate, preferably use the adjacent data computation frequency deviation in the left side; When the phase place of described pilot channel estimation less than 0 the time, select the data symbol on described pilot bit the right to carry out frequency deviation and estimate, preferably use the adjacent data computation frequency deviation in the right.

If the phase place of pilot bit channel estimation results ${\mathrm{\φ}}_{h\_\mathrm{slot}\_i}^{\left(m\right)}>0,$ With the left data position, preferred adjacent data position, the left side corresponds to the territory that is modulated to symbol so, for example PUSCH (Physical Uplink SharedChannel, up link is shared physical channel) then needs demodulating data is done inversefouriertransform, and declare firmly, obtain phase difference.

If the QPSK symbol is time-domain signal, then ${\hat{d}}_i^{\left(m\right)}=\mathrm{ifft}\left({\hat{s}}_i^{\left(m\right)}\right);$ If the QPSK symbol is frequency-region signal, then ${\hat{d}}_i^{\left(m\right)}={\hat{s}}_i^{\left(m\right)};$

The rectification data

And carry out hard decision, ${\hat{b}}_{i,\mathrm{hard}}^{\left(m\right)}=\mathrm{hard}\left({\hat{d}}_i^{\left(m\right)}\right),$ " hard " expression hard decision function; With the data after declaring firmly

Be modulated to symbol again

The planisphere of modulation constellation and rectification is identical.

Multiply by the conjugation of the symbol after the judgement with unsentenced symbol, the complex values that obtains asked phase place,, obtain the residual phase of data symbol, ${\mathrm{\φ}}_{d_i}^{\left(m\right)}\left(k\right)=\∠({\hat{d}}_i^{\left(m\right)}\left(k\right)\·{\hat{d}}_{i,\mathrm{had}}^{\left(m\right)}*\left(k\right));$ $\frac{M}{2}-L\≤k\≤\frac{M}{2}+L,$ L is adjustable parameter.

Step s204 according to the phase place of described phase information and pilot channel estimation, obtains the last phase potential difference.In the present embodiment, according to formula

Last phase potential difference Δ φ is obtained in calculating ^(m), φ wherein _H-slot-i ^(m)Be the phase place of pilot channel estimation,

Be the residual phase of data symbol, i is the data symbol sequence number.

Step s205 obtains frequency deviation value according to described last phase potential difference.In the present embodiment, according to formula $f=\frac{\mathrm{\Δ}{\mathrm{\φ}}^{\left(m\right)}}{2\mathrm{\π}\×0.5\×{10}^{-3}/7\×x}$ Calculate frequency deviation value f, wherein Δ φ ^(m)Be the last phase potential difference, x is the data symbol number at interval between pilot tone and the selected data symbol.

In step s203, if the phase place of pilot bit channel estimation results ${\mathrm{\φ}}_{h\_\mathrm{slot}\_i}^{\left(m\right)}\≤0,$ The position of demodulation right data so, adjacent data position, preferred the right, all the other processes are identical.

Embodiment two

A kind of frequency deviation estimating method based on pilot tone and data of the embodiment of the invention as shown in Figure 3, wherein step s301～s305 is identical with step s201～s205 among the embodiment one.With reference to Fig. 3, present embodiment is after step s305, and is further comprising the steps of:

Step s306 judges selection branch according to described frequency deviation value, and obtains the frequency deviation initial value corresponding with described branch.In the present embodiment, carry out branch according to the frequency deviation of the f that estimates and select, a kind of frequency deviation branch schematic diagram of present embodiment as shown in Figure 4, f _Th,-f _ThBe branch's separation, f ₁, f ₂, f ₃Be the frequency deviation initial value of branch's correspondence, f _Th,-f _Th, f ₁, f ₂, f ₃And branch's number all is parameter, obtains by emulation or outfield actual environment.

When-f _Th≤ f≤f _ThThe time,

Select branch 2, Δ f ₀=f ₂

As f＞f _ThThe time,

Select branch 3, Δ f ₀=f ₃

When f＜-f _ThThe time,

Select branch 1, Δ f ₀=f ₁

Step s307 carries out frequency deviation according to the frequency deviation initial value of described branch correspondence in conjunction with pilot tone and estimates.In the present embodiment, at first, to the channel estimation value H of user m ₁ ^(m)(k), H ₂ ^(m)(k) be divided into the Q section, in every section, carry out frequency domain smoothing.With continuous N _SmoothingChannel estimation value on=M/Q subcarrier is averaging, namely according to formula

${\stackrel{\‾}{H}}_{1,s}^{\left(m\right)}=\frac{1}{N_{\mathrm{smoothing}}}\underset{j=1}{\overset{N_{\mathrm{smoothing}}}{\mathrm{\Σ}}}{H}_1^{\left(m\right)}((s-1)\×N_{\mathrm{smoothing}}+j),$ 1≤s≤Q, 1≤j≤N _SmoothingWith

${\stackrel{\‾}{H}}_{2,s}^{\left(m\right)}=\frac{1}{N_{\mathrm{smoothing}}}\underset{j=1}{\overset{N_{\mathrm{smoothing}}}{\mathrm{\Σ}}}{H}_2^{\left(m\right)}((s-1)\×N_{\mathrm{smoothing}}+j),$ 1≤s≤Q，1≤j≤N _smoothing

Obtain mean value H _{1, s} ^(m)And H _{2, s} ^(m), wherein s is the sequence number of group, the sequence number of element during j is every group.

Then, with Δ f ₀Channel estimation value H with pilot bit ₁ ^(m)(k), H ₂ ^(m)(k) combine and carry out frequency deviation and estimate.Select corresponding initial frequency deviation Δ f with branch ₀Participate in current residual frequency deviation and calculate Δ f ₀Can be that each reception antenna obtains respectively, namely obtain Δ f _{0, ka}, also can be to obtain again respectively to average, i.e. Δ f ₀:

Present embodiment is according to formula

$\left\{\begin{array}{c}{\mathrm{\Δ\Δf}}_{s,\mathrm{ka}}=\frac{\∠\left({\stackrel{\‾}{H}}_{2,s}^{\left(m\right)}\right)/\left({\stackrel{\‾}{H}}_{1,s}^{\left(m\right)}\right)}{2\mathrm{\π}\·t}-\mathrm{\Δ}{f}_0+l\×2000\\ {\mathrm{\Δ\Δf}}_{\mathrm{ka}}=\frac{1}{Q}\underset{s}{\overset{Q}{\mathrm{\Σ}}}{\mathrm{\Δ\Δf}}_{s,\mathrm{ka}}\\ {\mathrm{\Δf}}_{\mathrm{ka}}={\mathrm{\Δf}}_0+{\mathrm{\Δ\Δf}}_{\mathrm{ka}}\end{array}\right.$

Obtain frequency deviation and estimate Δ f _Ka, wherein ∠ is for asking argument of a complex number main value computing (namely asking phase place), and t is at interval number between two subcarriers that calculate phase differences, Δ f ₀Be the frequency deviation initial value corresponding with branch, l is for making Δ Δ f _{S, ka}The integer of ∈ (1000,1000), s is the sequence number of group, Δ Δ f _{S, ka}With Δ Δ f _KaBe middle frequency deviation value.

Embodiment three

The structure of a kind of frequency deviation estimation device based on pilot tone and data of the embodiment of the invention comprises phase place acquiring unit, phase information acquiring unit, last phase potential difference acquiring unit, frequency deviation value acquiring unit, frequency deviation initial value acquiring unit and the frequency deviation estimating unit of pilot bit frequency domain channel estimated value acquiring unit, pilot channel estimation as shown in Figure 5.Wherein the phase place acquiring unit of pilot channel estimation is connected with pilot bit frequency domain channel estimated value acquiring unit, phase information acquiring unit and last phase potential difference acquiring unit respectively, last phase potential difference acquiring unit is connected with the frequency deviation value acquiring unit with the phase information acquiring unit respectively, and frequency deviation initial value acquiring unit is connected with frequency deviation estimating unit with the frequency deviation value acquiring unit respectively.

Pilot bit frequency domain channel estimated value acquiring unit is used for obtaining targeted customer's pilot bit frequency domain channel estimated value; The phase place acquiring unit of pilot channel estimation is used for calculating the phase place of pilot channel estimation; The phase information acquiring unit is used for selecting data symbol according to the phase place of described pilot channel estimation, and obtains the phase information that frequency deviation causes according to described data symbol; Last phase potential difference acquiring unit is used for the phase place according to described phase information and pilot channel estimation, obtains the last phase potential difference; The frequency deviation value acquiring unit is used for obtaining frequency deviation value according to described last phase potential difference; The frequency deviation value that frequency deviation initial value acquiring unit is used for obtaining according to described frequency deviation value acquiring unit is judged selection branch, and obtains the frequency deviation initial value corresponding with described branch; Frequency deviation estimating unit is used for carrying out the frequency deviation estimation according to the frequency deviation initial value of described branch correspondence in conjunction with pilot tone.

The present invention estimates frequency deviation initial value scope according to the phase difference between pilot tone and the OFDM data symbol, estimate frequency deviation value with the frequency deviation initial value scope that estimates in conjunction with pilot tone again, thereby improve receiver performance frequency deviation estimated capacity, can estimate the relative frequency deviation between base station and the terminal effectively, reduce ofdm system owing to sub-carrier orthogonality being destroyed the interference that brings, improve receiver to estimation and the compensation range of frequency deviation, owing to used branch's system of selection, therefore increase base station and terminal greatly and carry out the limit of power that frequency deviation is estimated, the present invention makes the receiver can accurately, the stable frequency offset correction that carries out.When especially having big frequency deviation in the high-speed mobile environment link, the frequency deviation value that exists in the estimating system more accurately is for telecommunication service quality provides reliable guarantee.

The above only is preferred implementation of the present invention; should be pointed out that for those skilled in the art, under the prerequisite that does not break away from the technology of the present invention principle; can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.

Claims (12)

1. the frequency deviation estimating method based on pilot tone and data is characterized in that, said method comprising the steps of:

Obtain targeted customer's pilot bit frequency domain channel estimated value;

Calculate the phase place of pilot channel estimation;

Phase place according to described pilot channel estimation is selected data symbol, and obtains the phase information that frequency deviation causes according to described data symbol;

Obtain the last phase potential difference according to the phase place of described phase information and pilot channel estimation, specifically comprise:

According to formula

Last phase potential difference Δ φ is obtained in calculating ^(m), wherein

Be the phase place of pilot channel estimation,

Be the residual phase of data symbol, i is the data symbol sequence number, and m is the user;

Obtain frequency deviation value according to described last phase potential difference.

2. the frequency deviation estimating method based on pilot tone and data as claimed in claim 1 is characterized in that, in the step of the described pilot bit frequency domain channel estimated value of obtaining the targeted customer, specifically comprises:

According to formula $H_1^{\left(m\right)}\left(k\right)=\frac{Y_1^{\left(m\right)}\left(k\right)}{X^m\left(k\right)},$ 1≤k≤M and $H_2^{\left(m\right)}\left(k\right)=\frac{Y_2^{\left(m\right)}\left(k\right)}{X^m\left(k\right)},$ 1≤k≤M obtains targeted customer's pilot bit frequency domain channel estimated value, wherein

Be the channel estimation value of pilot tone 1, Be the channel estimation value of pilot tone 2,

Be the frequency domain receiving sequence of pilot tone 1,

Be the frequency domain receiving sequence of pilot tone 2, X ^(m)(k) be local pilot tone sign indicating number, length is M, and m is the user.

3. the frequency deviation estimating method based on pilot tone and data as claimed in claim 2 is characterized in that, in the step of the phase place of described calculating pilot channel estimation, specifically comprises:

According to formula

${\mathrm{\φ}}_{h\_\mathrm{slot}\_i}^{\left(m\right)}=\frac{1}{M}\underset{k=1}{\overset{M}{\mathrm{\Σ}}}\∠H_{h\_\mathrm{slot}\_i}^{\left(m\right)}\left(k\right)-n\·\frac{\mathrm{\π}}{2}$

Calculate the phase place of pilot channel estimation ∠ is for asking the computing of argument of a complex number main value, Be pilot bit frequency domain channel estimated value, h_slot_i=1or2, n ∈ integer makes

4. the frequency deviation estimating method based on pilot tone and data as claimed in claim 3 is characterized in that, described phase place according to pilot channel estimation selects data symbol to be specially:

When the phase place of described pilot channel estimation greater than 0 the time, select the data symbol on the described pilot bit left side;

When the phase place of described pilot channel estimation is less than or equal to 0, select the data symbol on described pilot bit the right.

5. the frequency deviation estimating method based on pilot tone and data as claimed in claim 4 is characterized in that,

When the phase place of described pilot channel estimation greater than 0 the time, select the adjacent data symbol in the described pilot bit left side;

When the phase place of described pilot channel estimation is less than or equal to 0, select the adjacent data symbol in described pilot bit the right.

6. the frequency deviation estimating method based on pilot tone and data as claimed in claim 4 is characterized in that, describedly obtains the phase information that frequency deviation causes according to described data symbol and is specially:

The data symbol of described selection is corresponded to the territory of modulation symbol, rectification, and declare data firmly, the data after declaring firmly are modulated to symbol again;

The conjugation that multiply by the symbol after the judgement with unsentenced symbol obtains a complex values, and described complex values is asked phase place, obtains the residual phase of data symbol.

7. the frequency deviation estimating method based on pilot tone and data as claimed in claim 1 is characterized in that, the described step of obtaining frequency deviation value according to phase difference specifically comprises:

According to formula Calculate frequency deviation value f, wherein Δ φ ^(m)Be the last phase potential difference, x is the data symbol number at interval between pilot tone and the selected data symbol.

8. as each described frequency deviation estimating method based on pilot tone and data in the claim 1 to 7, it is characterized in that, after the described step of obtaining frequency deviation value according to phase difference, also comprise:

Judge selection branch according to described frequency deviation value, and obtain the frequency deviation initial value corresponding with described branch;

Frequency deviation initial value according to described branch correspondence carries out the frequency deviation estimation in conjunction with pilot tone.

9. the frequency deviation estimating method based on pilot tone and data as claimed in claim 8 is characterized in that, carries out in conjunction with pilot tone specifically comprising in the step of frequency deviation estimation at described frequency deviation initial value according to branch's correspondence:

Pilot bit frequency domain channel estimated value with user m

Be divided into the Q section, in every section, carry out frequency domain smoothing, and to continuous N _SmoothingPilot bit frequency domain channel estimated value on=M/Q subcarrier is averaging, and obtains mean value

According to formula

$\left\{\begin{array}{c}{\mathrm{\Δ\Δf}}_{s,\mathrm{ka}}=\frac{\∠\left({\stackrel{\‾}{H}}_{2,s}^{\left(m\right)}\right)/\left({\stackrel{\‾}{H}}_{1,s}^{\left(m\right)}\right)}{2\mathrm{\π}\·t}-{\mathrm{\Δf}}_0+l\×2000\\ {\mathrm{\Δ\Δf}}_{\mathrm{ka}}=\frac{1}{Q}\underset{s}{\overset{Q}{\mathrm{\Σ}}}{\mathrm{\Δ\Δf}}_{s,\mathrm{ka}}\\ {\mathrm{\Δf}}_{\mathrm{ka}}={\mathrm{\Δf}}_0+{\mathrm{\Δ\Δf}}_{\mathrm{ka}}\end{array}\right.$

Obtain frequency deviation and estimate Δ f _Ka, wherein ∠ is for asking the computing of argument of a complex number main value, and t is at interval number between two subcarriers that calculate phase differences, Δ f ₀Be the frequency deviation initial value corresponding with branch, l is for making Δ Δ f _{S, ka}The integer of ∈ (1000,1000), s is the sequence number of group, Δ Δ f _{S, ka}With Δ Δ f _KaBe middle frequency deviation value.

10. the frequency deviation estimating method based on pilot tone and data as claimed in claim 9 is characterized in that, at the described mean value that obtains Step in, specifically comprise:

According to formula

${\stackrel{\‾}{H}}_{1,s}^{\left(m\right)}=\frac{1}{N_{\mathrm{smoothing}}}\underset{j=1}{\overset{N_{\mathrm{smoothing}}}{\mathrm{\Σ}}}{H}_1^{\left(m\right)}((s-1)\×N_{\mathrm{smoothing}}+j),$ 1≤s≤Q, 1≤j≤N _SmoothingWith

${\stackrel{\‾}{H}}_{2,s}^{\left(m\right)}=\frac{1}{N_{\mathrm{smoothing}}}\underset{j=1}{\overset{N_{\mathrm{smoothing}}}{\mathrm{\Σ}}}{H}_2^{\left(m\right)}((s-1)\×N_{\mathrm{smoothing}}+j),$ 1≤s≤Q，1≤j≤N _smoothing

Obtain mean value

Wherein s is the sequence number of group, the sequence number of element during j is every group.

11. the frequency deviation estimation device based on pilot tone and data is characterized in that, described device comprises:

Pilot bit frequency domain channel estimated value acquiring unit is for the pilot bit frequency domain channel estimated value of obtaining the targeted customer;

The phase place acquiring unit of pilot channel estimation is for the phase place of calculating pilot channel estimation;

The phase information acquiring unit is used for selecting data symbol according to the phase place of described pilot channel estimation, and obtains the phase information that frequency deviation causes according to described data symbol;

Last phase potential difference acquiring unit is used for obtaining the last phase potential difference according to the phase place of described phase information and pilot channel estimation, specifically comprises:

According to formula

Last phase potential difference Δ φ is obtained in calculating ^(m), wherein

Be the phase place of pilot channel estimation,

Be the residual phase of data symbol, i is the data symbol sequence number, and m is the user;

The frequency deviation value acquiring unit is used for obtaining frequency deviation value according to described last phase potential difference.

12. the frequency deviation estimation device based on pilot tone and data as claimed in claim 11 is characterized in that, described device also comprises:

Frequency deviation initial value acquiring unit, the frequency deviation value that is used for obtaining according to described frequency deviation value acquiring unit is judged selection branch, and obtains the frequency deviation initial value corresponding with described branch;

Frequency deviation estimating unit is used for carrying out the frequency deviation estimation according to the frequency deviation initial value of described branch correspondence in conjunction with pilot tone.

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