CN102075460B - Frequency offset estimating method and device based on data - Google Patents

Abstract

The invention discloses a frequency offset estimating method based on data, which comprises the steps of: obtaining a pilot frequency bit frequency-domain channel estimation value of a target user; obtaining phase information caused by the frequency offset according to the pilot frequency bit frequency-domain channel estimation value; obtaining phase difference among different OFDM (Orthogonal Frequency Division Multiplexing) symbol data or data on different subcarriers of an OFDM symbol according to the phase information; and obtaining a frequency offset value according to the phase difference. The invention also discloses a frequency offset estimation device based on the data. According to the invention, the performance frequency offset estimation capacity of a receiving machine can be improved, the relative frequency offset between a base station and a terminal is effectively estimated, the interference caused by the orthogonal damage on the subcarriers by an OFDM system is reduced, the estimation and compensation range of the frequency offset for the receiving machine is improved, especially when a large frequency offset exists in a high-speed mobile environment link, the frequency offset value existing the system can be more accurately estimated, and the reliable guarantee is provided for the communication service quality.

Description

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

Technical field

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

Background technology

LTE (Long Term Evolution, Long Term Evolution) project is 3GPP (ThirdGeneration Partnership Projects over the past two years, the new technology development project of maximum third generation partnership project) started, it improves and has strengthened the aerial access technology of 3G (Third Generation, 3G (Third Generation) Moblie technology).With 3G, compare, 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 the characteristics such as the availability of frequency spectrum is high, anti-multipath interference, and ofdm system can be resisted the impact that wireless channel brings effectively.LTE ul transmissions scheme adopts SC-FDMA (the Single Carrier Furequency Division Multiplexity with Cyclic Prefix, single carrier frequency division is multiplexing), in SC-FDMA transmission plan in up employing with Cyclic Prefix, use DFT (DiscreteFourier Transformation, discrete Fourier transform (DFT)) obtain frequency-region signal, then insert nil symbol 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 and disturbing between subchannel.Have a plurality of orthogonal sub-carriers in ofdm system, output signal is the stack of a plurality of sub-channel signals, and because subchannel covers mutually, this just has higher requirement to the orthogonality of intercarrier.

Due to the movement of terminal, can between base station and terminal, produce Doppler frequency shift, in mobile communication system, particularly, under High-speed Circumstance, this frequency displacement is especially obvious.Doppler frequency shift will make between Receiver And Transmitter to produce frequency error, 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 fast mobile terminal direction and signal propagation direction; V is the terminal movement velocity; C is propagation velocity of electromagnetic wave; f ₀for carrier frequency.

The LTE system is for mobile 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, do not fall net higher than the 350km/h mobile subscriber.In this velocity interval, Doppler frequency shift surpasses 400Hz, and base station and terminal must support enough compensate of frequency deviation technology could meet operation quality requirement.

For receiver, estimate and transmitter between frequency error and to complete correction of frequency errors be the function that receiver must complete.Terminal receives f _dfrequency displacement, send upward signal after the terminal locking downstream signal frequencies, uplink receiving will have 2*f _dfrequency displacement.

As shown in Figure 1, the direction of relative movement of terminal and base station is different for frequency deviation schematic diagram in existing a kind of fast mobile terminal process, can produce positive and negative different frequency deviation, establishes f ₀be the tranmitting frequency of base station, when terminal is moved to the direction away from base station, can produce negative frequency deviation-f _d, the frequency that terminal receives is f ₀-f _d, the frequency that base station receives is f ₀-2*f _d; When terminal is moved to the direction near base station, can produce positive frequency deviation f _d, the frequency that terminal receives is f ₀+ f _d, the frequency that base station receives is f ₀+ 2*f _d.When terminal is moved between two base stations, when from a base station, driving towards another base station, terminal there will be frequency hopping, 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 will be all 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 larger (when the counterpart terminal movement velocity is higher), in prior art, using pilot tone to do frequency deviation estimates, the frequency deviation region that can estimate is little, complexity is high, and when there is large frequency deviation in system, anti-noise ability descends to some extent.

Summary of the invention

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

For achieving the above object, technical scheme of the present invention provides a kind of frequency deviation estimating method of based on data, said method comprising the steps of: the pilot bit channel estimation in frequency domain value of obtaining the targeted customer; According to described pilot bit channel estimation in frequency domain value, obtain the phase information only caused containing frequency deviation; According to described phase information, obtain between different OFDM symbol datas or OFDM symbol different sub carrier on the phase difference of data; Obtain frequency deviation value according to described phase difference.

Further, in the step of the described pilot bit channel estimation in frequency domain 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 channel estimation in frequency domain 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 code, length is M, and m is the user.

Further, in the described step of only obtaining the phase information caused containing frequency deviation, specifically comprise: utilize the symbol data on described pilot bit channel estimation in frequency domain value demodulating data position; Correspond to the territory (for example, LTE system uplink " territory of modulation symbol " is exactly time domain, and descending " territory of modulation symbol " is exactly frequency domain) of modulation symbol, the rectification symbol, and firmly sentence data, the data after firmly sentencing are modulated to symbol again; The conjugation that is multiplied by the symbol after judgement with unsentenced symbol obtains a complex values, and described complex values is asked to phase place.

Further, in the described step of obtaining the phase difference between different OFDM symbol datas, specifically comprise: according to formula $\mathrm{\Δ}{\mathrm{\φ}}^{\left(m\right)}={\mathrm{\φ}}_{d_{i+x}}^{\left(m\right)}\left(k\right)-{\mathrm{\φ}}_{d_i}^{\left(m\right)}\left(k\right)$ Calculate the phase difference φ between different OFDM symbol datas ^(m), wherein with

for the phase place of different OFDM symbol datas, i is OFDM symbol sequence number, the symbolic number at interval between the OFDM symbol that x is two calculating phase differences, 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)for the phase difference between different OFDM symbol datas, the symbolic number at interval between the OFDM symbol that x is two calculating phase differences.

Further, in the described step of obtaining the phase difference of data on an OFDM symbol different sub carrier, specifically comprise: the phase place grouping that will try to achieve described complex values is level and smooth, is divided into Q group, every group of M/Q element; According to formula ${\stackrel{\‾}{\mathrm{\φ}}}_s=\frac{1}{M/Q}\underset{j=1}{\overset{M/Q}{\mathrm{\Σ}}}{\mathrm{\φ}}_{d_i}^{\left(m\right)}((s-1)*M/Q+j),$ 1≤s≤Q, 1≤j≤M/Q obtains in this OFDM symbol the phase of data on each subcarrier _s, wherein

for the phase place that described complex values is tried to achieve, s is the sequence number of group, j be every group in the sequence number of element; According to formula Δ φ ^(m)=φ _s+g-φ _scalculate the phase difference φ of data on different sub carrier ^(m), φ wherein _s+gand φ _sbe respectively the phase place of data on the different sub carrier group, the number at interval between the subcarrier group that g is two calculating phase differences.

Further, the described step of obtaining frequency deviation value according to phase difference specifically comprises: according to formula $f=\frac{\mathrm{\Δ}{\mathrm{\φ}}^{\left(m\right)}\×M\×\mathrm{\Δf}}{2\mathrm{\π}\×g\×M/Q}$ Calculate frequency deviation value f, wherein Δ φ ^(m)for the phase difference of data on different sub carrier, Δ f is sub-carrier frequencies, the number at interval between the subcarrier group that g is two calculating phase differences, and Q is the grouping number.

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

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

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

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 two time intervals between the pilot tone of calculating phase differences, Δ f ₀for 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 _kafor 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

${\stackrel{\‾}{H}}_{1,s}^{\left(m\right)}=\frac{1}{N_{\mathrm{smoothing}}}\underset{j=1}{\overset{N_{\mathrm{smoothing}}}{\mathrm{\Σ}}}{H}_1^{\left(m\right)}((s-1)\×N_{\mathrm{smoothing}}+j),$ 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, j be every group in the sequence number of element.

Technical scheme of the present invention also provides a kind of frequency deviation estimation device of based on data, and described device comprises: pilot bit channel estimation in frequency domain value acquiring unit, for obtaining targeted customer's pilot bit channel estimation in frequency domain value; The phase information acquiring unit, for according to described pilot bit channel estimation in frequency domain value, obtain the phase information only caused containing frequency deviation; The phase difference acquiring unit, for according to described phase information, obtain between different OFDM symbol datas or OFDM symbol different sub carrier on the phase difference of data; The frequency deviation value acquiring unit, for obtaining frequency deviation value according to described phase difference.

Further, described device also comprises: frequency deviation initial value acquiring unit, and select branch for the frequency deviation value judgement of obtaining according to described frequency deviation value acquiring unit, and obtain the frequency deviation initial value corresponding with described branch; Frequency deviation estimating unit, carry out the frequency deviation estimation for the frequency deviation initial value corresponding according to described branch in conjunction with pilot tone.

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

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

The accompanying drawing explanation

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

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

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

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

Fig. 5 is the flow chart of frequency deviation estimating method of a kind of based on data of the embodiment of the present invention three;

Fig. 6 is the flow chart of frequency deviation estimating method of a kind of based on data of the embodiment of the present invention four;

Fig. 7 is the structural representation of frequency deviation estimation device of a kind of based on data of the embodiment of the present invention five.

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 the present invention is described, but are not used for limiting the scope of the invention.

Embodiment mono-

The frequency deviation estimating method of a kind of based on data of the embodiment of the present invention as shown in Figure 2, comprises the following steps:

Step s201, obtain targeted customer's pilot bit channel estimation in frequency domain 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 channel estimation in frequency domain 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 code, length is M, φ ₁and φ ₂the t that comprises respectively pilot tone 1 correspondence ₁t with pilot tone 2 correspondences ₂channel phase characteristic and frequency deviation phase information constantly.

Step s202, according to described pilot bit channel estimation in frequency domain value, obtain the phase information only caused containing frequency deviation.In the present embodiment, with pilot bit channel estimation value demodulating data position, correspond to the territory that is modulated to symbol, PUSCH (Physical Uplink Shared Channel for example, up link is shared physical channel), need demodulating data is done to inversefouriertransform, rectification is also sentenced firmly, obtains phase difference between two data symbols; PDSCH (Physical Downlink Shared Channel, down link is shared physical channel), sentence firmly, obtains phase difference between two data symbols.

Adopt MMSE (Minimum MeanSquare Error, least mean-square error) demodulation method (also can adopt other demodulation methods, for example MF (Matched Filtering, matched filtering), ZF (Zero-Forcing, ZF)),

${\hat{s}}_i^{\left(m\right)}={({H_{h\_\mathrm{slot}\_i}^{\left(m\right)}}^H{H}_{h\_\mathrm{slot}\_i}^{\left(m\right)}+{\mathrm{\σ}}^2)}^{-1}{H_{h\_\mathrm{slot}\_i}^{\left(m\right)}}^H{r}_i^{\left(m\right)};$

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

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 " means the hard decision function; By the data after firmly sentencing

be modulated to again symbol the planisphere of modulation constellation and rectification is identical.

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

Step s203, according to described phase information, obtain the phase difference between different OFDM symbol datas.In the present embodiment, according to formula ${\mathrm{\Δ\φ}}^{\left(m\right)}={\mathrm{\φ}}_{d_{i+x}}^{\left(m\right)}\left(k\right)-{\mathrm{\φ}}_{d_i}^{\left(m\right)}\left(k\right)$ Calculate the phase difference φ between different OFDM symbol datas ^(m), wherein with

for the phase place of different OFDM symbol datas, i is OFDM symbol sequence number, the symbolic number at interval between the OFDM symbol that x is two calculating phase differences.

Step s204, obtain frequency deviation value according to described phase 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)for the phase difference between different OFDM symbol datas, the symbolic number at interval between the OFDM symbol that x is two calculating phase differences.

Embodiment bis-

The frequency deviation estimating method of a kind of based on data of the embodiment of the present invention as shown in Figure 3, wherein step s301～s304 with in embodiment mono-step s201～s204 is identical.With reference to Fig. 3, the present embodiment is after step s304, further comprising the steps of:

Step s305, select branch according to described frequency deviation value judgement, and obtain the frequency deviation initial value corresponding with described branch.In the present embodiment, according to the f estimated, frequency deviation is carried out to branching selection, a kind of frequency deviation branch schematic diagram of the present embodiment as shown in Figure 4, f _th,-f _thbranch's separation, f ₁, f ₂, f ₃frequency deviation initial value corresponding to branch, f _th,-f _th, f ₁, f ₂, f ₃and branch's number is all parameter, by emulation or outfield actual environment, obtain.

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 s306, the frequency deviation initial value corresponding according to described branch carries out the frequency deviation estimation in conjunction with pilot tone.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, carry out frequency domain smoothing in every section.By continuous N _smoothingchannel estimation value on=M/Q subcarrier is averaging, according to formula

${\stackrel{\&OverBar;}{H}}_{1,s}^{\left(m\right)}=\frac{1}{N_{\mathrm{smoothing}}}\underset{j=1}{\overset{N_{\mathrm{smoothing}}}{\mathrm{\&Sigma;}}}{H}_1^{\left(m\right)}((s-1)\&times;N_{\mathrm{smoothing}}+j),$ 1≤s≤Q, 1≤j≤N _smoothingwith

${\stackrel{\&OverBar;}{H}}_{2,s}^{\left(m\right)}=\frac{1}{N_{\mathrm{smoothing}}}\underset{j=1}{\overset{N_{\mathrm{smoothing}}}{\mathrm{\&Sigma;}}}{H}_2^{\left(m\right)}((s-1)\&times;N_{\mathrm{smoothing}}+j),$ 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, j be every group in the sequence number of element.

Then, by Δ f ₀channel estimation value H with pilot bit ₁ ^(m)(k), H ₂ ^(m)(k) combine and carry out the frequency deviation estimation.The corresponding initial frequency deviation Δ f with branching selection ₀participate in current residual frequency deviation and calculate, Δ f ₀can be that each reception antenna obtains respectively, obtain Δ f _{0, ka}, can be also to obtain again and average respectively, i.e. Δ f ₀:

The present embodiment is according to formula

$\left\{\begin{array}{c}\mathrm{\&Delta;\&Delta;}{f}_{s,\mathrm{ka}}=\frac{\&angle;\left({\stackrel{\&OverBar;}{H}}_{2,s}^{\left(m\right)}\right)/\left({\stackrel{\&OverBar;}{H}}_{1,s}^{\left(m\right)}\right)}{2\mathrm{\&pi;}\&CenterDot;t}-\mathrm{\&Delta;}{f}_0+l\&times;2000\\ \mathrm{\&Delta;\&Delta;}{f}_{\mathrm{ka}}=\frac{1}{Q}\underset{\text{s}}{\overset{Q}{\mathrm{\&Sigma;}}}\mathrm{\&Delta;\&Delta;}{f}_{s,\mathrm{ka}}\\ \mathrm{\&Delta;}{f}_{\mathrm{ka}}=\mathrm{\&Delta;}{f}_0+\mathrm{\&Delta;\&Delta;}{f}_{\mathrm{ka}}\end{array}\right.$

Obtain frequency deviation and estimate Δ f _ka, wherein ∠ is for asking argument of a complex number main value computing (asking phase place), and t is two time intervals between the pilot tone of calculating phase differences, Δ f ₀for 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 _kafor middle frequency deviation value.

Embodiment tri-

The frequency deviation estimating method of a kind of based on data of the embodiment of the present invention as shown in Figure 5, wherein step s501～s502 with in embodiment mono-step s201～s202 is identical.With reference to Fig. 5, the present embodiment, after step s502, comprises the following steps:

Step s503, according to described phase information, obtain the phase difference of data on an OFDM symbol different sub carrier.In the present embodiment, the phase place grouping that at first will try to achieve described complex values is level and smooth, is divided into Q group, every group of M/Q element.Then according to formula ${\stackrel{\&OverBar;}{\mathrm{\&phi;}}}_s=\frac{1}{M/Q}\underset{j=1}{\overset{M/Q}{\mathrm{\&Sigma;}}}{\mathrm{\&phi;}}_{d_i}^{\left(m\right)}((s-1)*M/Q+j),$ 1≤s≤Q, 1≤j≤M/Q obtains in this OFDM symbol the phase of data on each subcarrier _s, wherein

for the phase place that described complex values is tried to achieve, s is the sequence number of group, j be every group in the sequence number of element.Finally according to formula Δ φ ^(m)=φ _s+g-φ _scalculate the phase difference φ of data on different sub carrier ^(m), φ wherein _s+gand φ _sbe respectively the phase place of data on the different sub carrier group, the number at interval between the subcarrier group that g is two calculating phase differences.

Step s504, according to formula $f=\frac{\mathrm{\&Delta;}{\mathrm{\&phi;}}^{\left(m\right)}\&times;M\&times;\mathrm{\&Delta;f}}{2\mathrm{\&pi;}\&times;g\&times;M/Q}$ Calculate frequency deviation value f, wherein Δ φ ^(m)for the phase difference of data on different sub carrier, the length that M is a shared subcarrier of OFDM symbol, Δ f is sub-carrier frequencies (in LTE, Δ f is 15kHz), the number at interval between the subcarrier group that g is two calculating phase differences, Q is the grouping number.

Embodiment tetra-

The frequency deviation estimating method of a kind of based on data of the embodiment of the present invention as shown in Figure 6, wherein step s601～s604 with in embodiment mono-step s501～s504 is identical.With reference to Fig. 6, the present embodiment, after step s604, also comprises step s605 and s606, and these two steps are identical with step s305 and s306 in embodiment bis-respectively.

Embodiment five

The structure of the frequency deviation estimation device of a kind of based on data of the embodiment of the present invention as shown in Figure 7, comprises pilot bit channel estimation in frequency domain value acquiring unit, phase information acquiring unit, phase difference acquiring unit, frequency deviation value acquiring unit, frequency deviation initial value acquiring unit and frequency deviation estimating unit.Wherein, the phase information acquiring unit is connected with the phase difference acquiring unit with pilot bit channel estimation in frequency domain value acquiring unit respectively, the frequency deviation value acquiring unit is connected with frequency deviation initial value acquiring unit with the phase difference acquiring unit respectively, frequency deviation initial value acquiring unit and frequency deviation estimating unit.

Pilot bit channel estimation in frequency domain value acquiring unit is for obtaining targeted customer's pilot bit channel estimation in frequency domain value; The phase information acquiring unit, for according to described pilot bit channel estimation in frequency domain value, obtains the phase information only caused containing frequency deviation; The phase difference acquiring unit is for according to described phase information, obtain between different OFDM symbol datas or OFDM symbol different sub carrier on the phase difference of data; The frequency deviation value acquiring unit is for obtaining frequency deviation value according to described phase difference.Frequency deviation initial value acquiring unit is used for selecting branch according to described frequency deviation value judgement, and obtains the frequency deviation initial value corresponding with described branch; Frequency deviation estimating unit is for according to described branch, corresponding frequency deviation initial value carries out the frequency deviation estimation in conjunction with pilot tone.

The present invention is according to the phase difference estimation frequency deviation scope of initial values after data demodulates, estimate frequency deviation value with the frequency deviation scope of initial values estimated in conjunction with pilot tone again, thereby improve receiver performance frequency deviation estimated capacity, can effectively estimate the relative frequency deviation between base station and terminal, reduce ofdm system owing to sub-carrier orthogonality being destroyed to the interference brought, improve estimation and the compensation range of receiver to frequency deviation, owing to having used the branching selection method, therefore increase greatly the limit of power that base station and terminal are carried out the frequency deviation estimation, the present invention makes the receiver can accurately, the stable frequency offset correction that carries out.While especially in the high-speed mobile environment link, having large frequency deviation, the frequency deviation value existed in estimating system more accurately, for telecommunication service quality provides reliable guarantee.

The above is only the preferred embodiment of the present invention; it 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 (11)

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

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

According to described pilot bit channel estimation in frequency domain value, obtain the phase information only caused containing frequency deviation;

According to described phase information, obtain between different OFDM symbol datas or OFDM symbol different sub carrier on the phase difference of data;

Obtain frequency deviation value according to described phase difference;

Wherein, in the described step of obtaining the phase difference between different OFDM symbol datas, specifically comprise: according to formula

calculate the phase difference φ between different OFDM symbol datas ^(m), wherein

for the phase place of different OFDM symbol datas, i is OFDM symbol sequence number, the symbolic number at interval between the OFDM symbol that x is two calculating phase differences, and m is the user.

2. the frequency deviation estimating method of based on data as claimed in claim 1, is characterized in that, in the step of the described pilot bit channel estimation in frequency domain 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

Obtain targeted customer's pilot bit channel estimation in frequency domain value, wherein for the channel estimation value of pilot tone 1,

for the channel estimation value of pilot tone 2,

for the frequency domain receiving sequence of pilot tone 1,

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

3. the frequency deviation estimating method of based on data as claimed in claim 1, is characterized in that, in the described step of only obtaining the phase information caused containing frequency deviation, specifically comprises:

Utilize the symbol data on described pilot bit channel estimation in frequency domain value demodulating data position;

Correspond to the territory of modulation symbol, the rectification symbol, and firmly sentence data, the data after firmly sentencing are modulated to symbol again;

The conjugation that is multiplied by the symbol after judgement with unsentenced symbol obtains a complex values, and described complex values is asked to phase place.

4. the frequency deviation estimating method of based on 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)for the phase difference between different OFDM symbol datas, the symbolic number at interval between the OFDM symbol that x is two calculating phase differences.

5. the frequency deviation estimating method of based on data as claimed in claim 3, is characterized in that, in the described step of obtaining the phase difference of data on an OFDM symbol different sub carrier, specifically comprises:

The phase place grouping that to try to achieve described complex values is level and smooth, is divided into Q group, every group of M/Q element;

According to formula

1≤s≤Q, 1≤j≤M/Q obtains in this OFDM symbol the phase place of data on each subcarrier

wherein

for the phase place that described complex values is tried to achieve, s is the sequence number of group, j be every group in the sequence number of element;

According to formula

calculate the phase difference φ of data on different sub carrier ^(m), wherein

with

be respectively the phase place of data on the different sub carrier group, the number at interval between the subcarrier group that g is two calculating phase differences.

6. the frequency deviation estimating method of based on data as claimed in claim 5, 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)for the phase difference of data on different sub carrier, Δ f is sub-carrier frequencies, the number at interval between the subcarrier group that g is two calculating phase differences, and Q is the grouping number.

7. as the frequency deviation estimating method of the described based on data of claim 1 to 6 any one, it is characterized in that, after the described step of obtaining frequency deviation value according to phase difference, also comprise:

Select branch according to described frequency deviation value judgement, and obtain the frequency deviation initial value corresponding with described branch;

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

8. the frequency deviation estimating method of based on data as claimed in claim 7, is characterized in that, in the described frequency deviation initial value corresponding according to branch carries out the step of frequency deviation estimation in conjunction with pilot tone, specifically comprises:

Pilot bit channel estimation in frequency domain value by user m

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

According to formula

$\left\{\begin{array}{c}{\mathrm{\&Delta;\&Delta;f}}_{s,\mathrm{ka}}=\frac{\&angle;\left({\stackrel{\&OverBar;}{H}}_{2,s}^{\left(m\right)}\right)/\left({\stackrel{\&OverBar;}{H}}_{1,s}^{\left(m\right)}\right)}{2\mathrm{\&pi;}\&CenterDot;t}-\mathrm{\&Delta;}{f}_0+l\&times;2000\\ {\mathrm{\&Delta;\&Delta;f}}_{\mathrm{ka}}=\frac{1}{Q}\underset{s}{\overset{Q}{\mathrm{\&Sigma;}}}{\mathrm{\&Delta;\&Delta;f}}_{s,\mathrm{ka}}\\ {\mathrm{\&Delta;f}}_{\mathrm{ka}}={\mathrm{\&Delta;f}}_0+{\mathrm{\&Delta;\&Delta;f}}_{\mathrm{ka}}\end{array}\right.$

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 two time intervals between the pilot tone of calculating phase differences, Δ f ₀for 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 _kafor middle frequency deviation value.

9. the frequency deviation estimating method of based on data as claimed in claim 8, is characterized in that, at the described mean value that obtains

with

step in, specifically comprise:

According to formula

${\stackrel{\&OverBar;}{H}}_{1,s}^{\left(m\right)}=\frac{1}{N_{\mathrm{smoothing}}}\underset{j=1}{\overset{N_{\mathrm{smoothing}}}{\mathrm{\&Sigma;}}}{H}_1^{\left(m\right)}((s-1)\&times;N_{\mathrm{smoothing}}+j),1<s\&le;Q,1\&le;j\&le;N_{\mathrm{smoothing}}$ With

${\stackrel{\&OverBar;}{H}}_{2,s}^{\left(m\right)}=\frac{1}{N_{\mathrm{smoothing}}}\underset{j=1}{\overset{N_{\mathrm{smoothing}}}{\mathrm{\&Sigma;}}}{H}_2^{\left(m\right)}((s-1)\&times;N_{\mathrm{smoothing}}+j),1<s\&le;Q,1\&le;j\&le;N_{\mathrm{smoothing}}$

Obtain mean value

with

wherein s is the sequence number of group, j be every group in the sequence number of element.

10. the frequency deviation estimation device of a based on data, is characterized in that, described device comprises:

Pilot bit channel estimation in frequency domain value acquiring unit, for obtaining targeted customer's pilot bit channel estimation in frequency domain value;

The phase information acquiring unit, for according to described pilot bit channel estimation in frequency domain value, obtain the phase information only caused containing frequency deviation;

The phase difference acquiring unit, for according to described phase information, obtain between different OFDM symbol datas or OFDM symbol different sub carrier on the phase difference of data, wherein, the described phase difference obtained between different OFDM symbol datas specifically comprises: according to formula

calculate the phase difference φ between different OFDM symbol datas ^(m), wherein

with

for the phase place of different OFDM symbol datas, i is OFDM symbol sequence number, the symbolic number at interval between the OFDM symbol that x is two calculating phase differences, and m is the user;

The frequency deviation value acquiring unit, for obtaining frequency deviation value according to described phase difference.

11. the frequency deviation estimation device of based on data as claimed in claim 10, is characterized in that, described device also comprises:

Frequency deviation initial value acquiring unit, select branch for the frequency deviation value judgement of obtaining according to described frequency deviation value acquiring unit, and obtain the frequency deviation initial value corresponding with described branch;

Frequency deviation estimating unit, carry out the frequency deviation estimation for the frequency deviation initial value corresponding according to described branch in conjunction with pilot tone.

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