CN1556589A - Method of mobile communicaton frequency deviation measurement and device thereof - Google Patents

Abstract

The invention provides a method and device for detecting signal frequency bias in mobile communication system. The method includes: receiving the signal; carrying on channel estimation to the signal, in order to acquire the estimation result of original channel; the primary component of the reference signal is restored according to the original estimation result; the frequency difference can be acquired according to the comparing result of the primary component of the reference signal and the original received si8gnal. The device includes: receiving device; channel estimating device; judging device; reconstructing device; the relative device; integrating device; frequency bias acquiring device. The invention develops the estimation range of terminal frequency difference of the channel estimating code system.

Description

The method and apparatus that the mobile communication frequency deviation is measured

Technical field

The present invention relates to mobile communication, relate in particular to the method and apparatus of mobile communication measuring frequency deviation, specifically adopt channel estimating code to realize the measurement of frequency departure; Be a kind ofly to be applicable to slot CDMA or similarly to adopt the terminal of channel estimating code system to carry out the method for frequency deviation measurement.

Background technology

Outstanding feature is exactly the complexity and the time variation of its channel in the wireless mobile communications.In the coherent reception scheme, need estimate channel and measure at receiving terminal, utilize the channel response that obtains that signal is carried out coherent detection then.Because channel response is to be determined in the propagation of wireless channel and the characteristic of receiving equipment by transmitting apparatus, radio-frequency carrier, the variation of characteristics such as the frequency departure of equipment and drift, radio propagation channel, terminal move the Doppler frequency shift that causes and the variation etc. that declines, and all will bring the time of channel response to change and the final performance that influences system.At receiving terminal, the variation of channel must be caught and follow the tracks of to channel estimating and measurement, can guarantee the performance of Data Receiving demodulation.So the measurement of frequency departure and calibration are the requisite important steps of mobile communication system equipment operate as normal.

Burst structure (seeing Fig. 1 for details) with the business time-slot of TD-SCDMA (being 3GPP 1.28Mcps TDD) system is an example, channel estimating code (the midamble sign indicating number at burst middle part, intermediate code) be used for carrying out channel estimating, the data block on both sides is used for transmit traffic data.The parameter of TD-SCDMA system is: time slot is long to be T _TS=0.675ms=675us; Symbol (spreading gain is 16) length is: T _S=12.5us; Chip length is: T _C=0.781us=781ns.Each time slot has two data blocks, and each data block contains 22 symbols (spreading gain is 16), and intermediate code has the individual chip of 144 (128+16).

Present existing frequency deviation measurement method is: utilize according to time in the piece constant channel estimating and the result that obtains of detection algorithm handle, according to court verdict channel variation is estimated near the partial data symbol of channel estimating code, utilize the deviation of estimating to carry out iteration calibration calculation process, transmission data that finally are restored and accurate estimation of deviation.

This method can obtain good frequency deviation measurement result in certain frequency difference scope, its signal-to-noise performance is good.But this method is unsuitable for big offset frequency situation.Along with the increase of frequency departure, the symbolic number that can participate in frequency offset estimating reduces, and the noiseproof feature of frequency deviation measurement descends; When exemplary frequency deviation values was very big, this method can not be used.Typical example is: start working when carrying out cell initial search in terminal receiver, at first carry out the frequency coarse adjustment, utilize descending pilot frequency measuring frequency deviation, by coarse adjustment frequency departure is adjusted to a small range.Finish laggard line frequency accurate adjustment in the frequency coarse adjustment, at this moment just adopt above-mentioned method measuring frequency deviation.And, can only utilize when accurate adjustment begins near the less symbol of channel estimating code and measure, must just can obtain measurement result comparatively reliably by multi-frame mean.

Therefore, wish to have a kind of method and apparatus that is applicable to the good frequency deviation measurement result of quick acquisition of big frequency deviation.

Summary of the invention

The objective of the invention is shortcoming, a kind of method and apparatus that utilizes channel estimating code measuring frequency deviation is provided at above-mentioned prior art.

The invention provides a kind of method of mobile communication signal frequency deviation measurement, comprise step:

Received signal,

Signal to described reception carries out channel estimating, to obtain original estimation result;

According to described original estimation result, recover the fundamental component of reference signal;

Fundamental component and described received signal result relatively according to the reference signal of described recovery obtain frequency departure.

Alternatively, the step of the fundamental component of described recovery reference signal comprises:

According to pre-defined rule described original estimation result is carried out the finite time decision process, to obtain the locational response of finite time with tap of strong signal;

Utilize channel estimation results after the described finite time decision process to recover the fundamental component of reference signal.

Preferably, the step of described acquisition frequency departure comprises:

Carry out relevant to the reference signal fundamental component of recovering with received signal;

Described correlated results is carried out chip to be merged;

The result who utilizes described chip to merge obtains frequency departure.

Alternatively, the described step that the signal that receives is carried out channel estimating comprises: the midamble to described received signal partly carries out the response that frequency domain and time domain are handled the acquisition original channel;

The impulse response of original channel satisfies following formula:

$\hat{h}=\mathrm{ifft}(\mathrm{fft}\left(e_{\mathrm{mid}}\right)./\mathrm{fft}\left(m_{\mathrm{basic}}\right))$

Wherein: The original estimated result of expression channel impulse response, m _BasicBe basic midamble sign indicating number, e _MidBe the midamble part of received signal, fft and ifft represent the inverse operation of rapid fourier change and rapid fourier change respectively.

Preferably, described step of original estimation result being carried out the finite time decision process according to pre-defined rule comprises:

The power of each tap of more described channel response and prearranged signals thresholding;

Keep of the tap of the power of described channel response greater than described prearranged signals thresholding;

The power of putting described channel response is zero less than the tap of described prearranged signals thresholding;

Or

According to predetermined tap number thresholding, the response of the tap of the described predetermined tap number of descending reservation;

Or

Keep of the tap of the signal to noise ratio of described channel response greater than predetermined signal-noise ratio threshold;

The signal to noise ratio of putting described channel response is zero less than the tap of described predetermined signal to noise ratio.

Alternatively, the described formula that utilizes channel estimation results after the finite time decision process to recover the reference signal fundamental component is as follows:

${\hat{s}}_{\mathrm{mid}}=\mathrm{ifft}(\mathrm{fft}\left(h^{\′}\right).*\mathrm{fft}\left(m_{\mathrm{basic}}\right))$

Wherein, h ' is the channel estimating after the finite time decision process, m _BasicBe basic midamble sign indicating number,

For utilizing the reference signal fundamental component that channel estimation results recovered after the finite time decision process, fft and ifft represent the inverse operation of rapid fourier change and rapid fourier change respectively.

Preferably, described reference signal fundamental component with recovery is carried out relevant satisfied with received signal:

$r=\mathrm{conj}\left({\hat{s}}_{\mathrm{mid}}\right).*e_{\mathrm{mid}}$

That is: $r=({\hat{s}}_{\mathrm{mid},0}^{*}\·e_{\mathrm{mid},0},{\hat{s}}_{\mathrm{mid},1}^{*}\·e_{\mathrm{mid},1},\mathrm{\Λ},{\hat{s}}_{\mathrm{mid},(P-1)}^{*}\·e_{\mathrm{mid},(P-1)})$

Wherein: computing is gripped in conj () expression altogether; * represent that data of corresponding positions multiplies each other respectively in two arrays; Be the reference signal fundamental component of recovering, ${\hat{s}}_{\mathrm{mid}}=\{{\hat{s}}_{\mathrm{mid},0},\mathrm{\Λ},{\hat{s}}_{\mathrm{mid},P-1}\};$ e _MidBe received signal, e _Mid={ e _{Mid, 0}, Λ, e _{Mid, P-1}; P=128 is received signal length; R is the result of related operation.

Alternatively, correlated results being carried out the step that chip merges satisfies:

d＝(d ₀，d ₁，Λ，d _L-1，)

$d_i=\underset{j=\mathrm{jQ}}{\overset{\mathrm{iQ}+Q-1}{\mathrm{\Σ}}}{r}_j---i=\mathrm{0,1},\mathrm{\Λ},L-1$

Wherein: L=P/Q is the data length after merging; Q comprises: 4,8,16,32,64 for merging factor; D is the data after merging.

Preferably, the result who utilizes chip to merge, the step that obtains frequency departure comprises:

Obtain phase deviation, satisfy:

$\mathrm{\Δ\θ}=\frac{1}{L-1}\underset{m=1}{\overset{L-1}{\mathrm{\Σ}}}\left(\frac{1}{m}\underset{n=0}{\overset{m-1}{\mathrm{\Σ}}}\left(\frac{{\mathrm{\θ}}_{d,m}-{\mathrm{\θ}}_{d,n}}{m-n}\right)\right);$

Or

$\mathrm{\Δ\θ}=\frac{1}{\underset{k=1}{\overset{L-1}{\mathrm{\Σ}}}(L-k)\×k}\underset{m=1}{\overset{L-1}{\mathrm{\Σ}}}\underset{m=0}{\overset{m-1}{\mathrm{\Σ}}}({\mathrm{\θ}}_{d,m}-{\mathrm{\θ}}_{d,n})$

Wherein: Δ θ obtains phase deviation, θ for asking _{D, i}, i=0 Λ L-1 is for merging the phase place of back data d;

According to the described phase deviation of obtaining, obtain frequency departure, satisfy:

$\mathrm{\Δf}=\frac{1}{2\mathrm{\π}{T}_{C}Q}\×\mathrm{\Δ\θ}$

Wherein: T _CBe the chip width, Δ f is the frequency departure that obtains.

The present invention also provides a kind of the realization to comprise as the device of the mobile communication signal frequency deviation measurement method of claim 1-9:

Receiving system is used to receive mobile communication signal;

Channel estimating apparatus carries out channel estimating to the signal of described reception, to obtain original estimation result;

Judgment device is carried out the finite time decision process according to pre-defined rule to described original estimation result, to obtain the locational response with tap of strong signal of finite time;

Reconstructing device utilizes channel estimating after the described finite time decision process to recover the fundamental component of reference signal;

Relevant apparatus carries out relevant to the fundamental component of recovering reference signal with received signal;

Merge device, described correlated results is carried out chip merge;

The frequency departure deriving means, the result who utilizes described chip to merge obtains frequency departure.

Utilize the present invention, expanded the frequency departure estimation range of the terminal of employing channel estimating code system (as TD-SCDMA).

Description of drawings

Fig. 1 is a TD-SCDMA business time-slot burst structure schematic diagram in the prior art.

Fig. 2 illustrates and adopts channel estimating code to realize the flow chart of frequency deviation measurement method in the embodiments of the invention.

Fig. 3 is signal flow diagram and a schematic diagram of realizing channel estimating in the embodiment of the invention.Its process is: elder generation is with the midamble part e of received signal _MidWith basic midamble sign indicating number m _BasicCarry out rapid fourier change, then both are divided by, next the result of being divided by is carried out anti-Fourier transformation, export original estimation result at last.This module can be reduced to independently CHE (CHannel Estimation) module.

Fig. 4 is a channel estimation results schematic diagram in the embodiment of the invention.Channel condition is: eight users are arranged, code channel of each CU, spread spectrum coefficient SF=16, awgn channel, signal to noise ratio (Eb/N0) SNR=0dB.

Fig. 5 is the decision process schematic diagram of device of finite time decision process example 1 in the embodiment of the invention.Its process is: ask the power of original each tap of estimated result of channel impulse response, get wherein maximum and multiply by thresholding ε and obtain threshold value, with each tap power and gained threshold ratio, power then keeps greater than the tap of threshold value, otherwise then puts 0.All finite time decision process modules all use independently PP (Post Processing) module to represent.

Fig. 6 is a finite time decision process device shown in Figure 5 court verdict in ε=1/4 o'clock.

Fig. 7 is the decision process schematic diagram of device of finite time decision process example 2 in the embodiment of the invention.Its process is: ask the power of original each tap of estimated result of channel impulse response, ordering (needing to keep original position information) keeps prominent 128 a ε tap according to the restriction of thresholding ε, and all the other taps put 0.

Fig. 8 is a finite time decision process device shown in Figure 7 court verdict in ε=1/6 o'clock.

Fig. 9 is the decision process schematic diagram of device of finite time decision process example 3 in the embodiment of the invention.Its process is: ask the power of original each tap of estimated result of channel impulse response, with the noise power σ of noise gate ε and estimation _n ²Product ε σ _n ²Relatively, power then keeps greater than the tap of threshold value, otherwise then puts 0.

Figure 10 is the schematic diagram that recovers reference signal in the embodiment of the invention.Its process is: earlier with reprocessing h ' and basic midamble sign indicating number m as a result _BasicCarry out rapid fourier change, then both are multiplied each other, next multiplied result is carried out anti-Fourier transformation, the reference signal that output at last recovers.This module can be reduced to an independently Rebuild module.

Figure 11 is the realization schematic diagram of phase deviation estimation method 1 in the embodiment of the invention.Its process is: the phase angle θ of relevant amalgamation result _dBy MUX, multistage (from 1 grade to the L-1 level) asks phase deviation respectively, adds up the estimated result of average multistage phase deviation, output phase estimation of deviation.The phase deviation estimation module all is simplified shown as an independently Phase-offset module.

Figure 12 is the realization schematic diagram of phase deviation estimation method 2 in the embodiment of the invention.Its process is: the phase angle θ of relevant amalgamation result _dBy MUX, multistage (from 1 grade to the L-1 level) asks phase angle poor of relevant amalgamation result respectively, adds up, and population mean is obtained phase deviation and estimated the output phase estimation of deviation.

Figure 13 is the implement device schematic diagram that the whole frequency departure of the embodiment of the invention is estimated.Its process is identical with the flow chart of Fig. 2.

Figure 14 shows the channel estimating code of utilizing of the embodiment of the invention and measures frequency deviation, and the error rate when in view of the above data being proofreaied and correct, do not carry out the adjustment of data and not having frequency deviation.

Figure 15 shows the channel estimating code of utilizing of the embodiment of the invention and measures frequency deviation, and correction data and estimate frequency deviation with data symbol in view of the above, and carries out the error rate of the adjustment of data in view of the above.

Embodiment

Implement and understand the present invention for the ease of persons skilled in the art, describe method and apparatus of the present invention with reference to accompanying drawing by embodiment respectively below.

At first with reference to Fig. 2, Fig. 2 illustrates and adopts channel estimating code to realize the flow chart of the method for frequency deviation measurement in the embodiment of the invention.At 3GPP TDD system or similarly adopt the terminal of channel estimating code system, adopt the method for utilizing channel estimating code measuring frequency deviation in the embodiment of the invention, may further comprise the steps:

In step 1, channel estimating: carry out channel estimating to received signal, obtain original estimation result; This is the work that receiver must be done, and can obtain the channel estimation results of multi-user multi-path Complex Channel.

In step 2, the finite time decision process: original channel estimation results is handled, only kept the locational response of finite time with tap of strong signal, and the response zero setting in all the other taps.The fundamental component that this has kept channel response is to carry out the basis that decision-feedback is handled.

In step 3, recover reference signal: utilize channel estimating after the finite time decision process to recover the fundamental component of reference signal; Be equivalent to utilize decision-feedback to recover a reference signal of having eliminated frequency departure.

In step 4, related operation: the calculating reference signal is relevant with received signal; Related operation has provided the deviation of received signal and reference signal.

In step 5, chip merges: correlated results is carried out chip merge; Correlated results is carried out chip merge, to improve the noise resisting ability of receiver.

In step 6, frequency departure is estimated: the resulting estimate frequency departure that utilizes chip to merge; Calculate frequency deviation by the phase deviation of utilizing related operation chip amalgamation result.

In this embodiment,, specifically describe below by some mathematical derivations and test result in order to describe the present invention better at 3GPP LCR TDD system.Wherein, signal structure as shown in Figure 1, the midamble of received signal part can be expressed as:

e _mid＝Gh+n ₀ (1)

Wherein, e _MidBe received signal, G is the sytem matrix by basic midamble sign indicating number decision, and h is corresponding channel response vector, n ₀Interference and noise in the expression channel.

Basic midamble code length is 128, and it is as follows to establish its expression formula:

m _basic＝(m ₁，m ₂Λm ₁₂₈)

Sytem matrix then $G=\left[\begin{array}{ccc}{m}_1& m_{128}& \mathrm{\&Lambda;}{m}_2\\ m_2& {\mathrm{<figure-callout\; id="1"\; label="m"\; filenames="A20041000011900212.png,A20041000011900221.png"\; state="\{\{state\}\}">m</figure-callout>}}_1& \mathrm{\&Lambda;}{m}_{127}\\ M& M& M\\ m_{128}& m_{127}& \mathrm{\&Lambda;}{\mathrm{<figure-callout\; id="1"\; label="m"\; filenames="A20041000011900212.png,A20041000011900221.png"\; state="\{\{state\}\}">m</figure-callout>}}_1\end{array}\right]$

Refer again to Fig. 2,, carry out channel estimating in step 1:

In this embodiment of TD-SCDMA system,------B.steiner estimator that used a kind of channel estimation methods of low-cost, this estimator uses training sequence (midamble sign indicating number), jointly estimates the channel impulse response of each user in the same time slot simultaneously.Carry out channel estimating to received signal, the formula that obtains original estimation result is as follows:

$\hat{h}=G^{-1}{e}_{\mathrm{mid}}---\left(2\right)$

Because the G matrix of above-mentioned formation is a cyclic correlation matrix,, obtain like this so following formula can be simplified calculating by asking FFT:

$\hat{h}=\mathrm{ifft}(\mathrm{fft}\left(e_{\mathrm{mid}}\right),/\mathrm{fft}\left(m_{\mathrm{basic}}\right))---\left(3\right)$

Fig. 3 is the signal flow diagram and the schematic diagram of the realization channel estimating apparatus of the embodiment of the invention.By this device, can realize the result of formula 3.Whole channel estimation process can be regarded as a CHE module.In an embodiment of the present invention, eight users are arranged, code channel of each CU, spread spectrum coefficient SF=16, awgn channel, signal to noise ratio (Eb/NO) SNR=0dB by channel estimation process, obtains original estimation result such as Fig. 4.

As seen in Figure 4,8 users' main footpath is very obvious, and this shows that the channel estimation scheme that embodiments of the invention adopt is effective.

Refer again to Fig. 2, in step 2, the finite time decision process:

To original channel estimation results

Handle, only keep the locational response of finite time with tap of strong signal, and the response zero setting in all the other taps.

The method that adopts in the finite time decision process example 1 of the embodiment of the invention is: the setting signal thresholding, directly accept or reject according to the power of channel response.The criterion that thresholding is set is to remove the noise tap as far as possible, the stick signal tap.According to the difference of signal to noise ratio, have different proportionate relationships between signal tap and noise tap.Through taking all factors into consideration, think that ε can get 1/2～1/8.Utilize tap power maximum to adjudicate, obtain

Fig. 5 is the decision process schematic diagram of device of finite time decision process example 1 in the embodiment of the invention.

Fig. 6 shows finite time decision process device shown in Figure 5 court verdict in ε=1/4 o'clock; As can be seen, 8 users' shown in Figure 4 main footpath, i.e. 8 taps the strongest are just in time tested comes out, and the threshold setting that ε=1/4 is described is suitable herein.

Fig. 7 is the decision process schematic diagram of device of finite time decision process example 2 in the embodiment of the invention.This is by setting the tap number thresholding, only keeping the response of several stronger taps by tap number.In an embodiment of the present invention, set thresholding ε, the 128 ε tap that the number of winning the confidence is the strongest.The criterion that thresholding is set is still for removing the noise tap as far as possible, the stick signal tap, noise greatly the time multipath component may be fallen into oblivion, remove the noise tap so pay the utmost attention to.Look concrete condition, thresholding ε can choose between 1/4～1/8.

Fig. 8 shows finite time decision process device shown in Figure 7 court verdict in ε=1/6 o'clock.As can be seen, 8 users' shown in Figure 4 main footpath, i.e. 8 taps the strongest are just in time tested comes out, and illustrates that being arranged on of thresholding is suitable herein.

Fig. 9 is the decision process schematic diagram of device of finite time decision process example 3 in the embodiment of the invention.This is by setting signal-noise ratio threshold.If ε＞0 utilizes the noise power σ that measures _n ²Obtain the channel estimating h ' after the finite time decision process.The selection rule of thresholding ε is to remove most of noise taps, simultaneously the stick signal tap.As calculated, ε can get 5～8.Utilize signal-noise ratio threshold to adjudicate, obtain

In step 3, recover reference signal:

This is, utilizes channel estimating h ' after the finite time decision process to recover the fundamental component of reference signal:

${\hat{s}}_{\mathrm{mid}}=G{h}^{\&prime;}---\left(6\right)$

The reference channel estimating part because the G matrix is a cyclic correlation matrix, so can simplify calculating by asking FFT, obtains like this:

${\hat{s}}_{\mathrm{mid}}=\mathrm{ifft}(\mathrm{fft}\left(h^{\&prime;}\right).*\mathrm{fft}\left(m_{\mathrm{basic}}\right))---\left(7\right)$

Figure 10 is the schematic diagram of the recovery reference signal of the embodiment of the invention, this process can be regarded as Rebuild (reconstruction) module.By this device, can obtain the result of formula 7.

Then, in step 4, carry out related operation: to calculate relevant (pursuing chip is correlated with) of reference signal and received signal:

$r=\mathrm{conj}\left({\hat{s}}_{\mathrm{mid}}\right),*e_{\mathrm{mid}}---\left(8\right)$

Or:

$r=({\hat{s}}_{\mathrm{mid},0}^{*}\&CenterDot;e_{\mathrm{mid},0},{\hat{s}}_{\mathrm{mid},1}^{*}{e}_{\mathrm{mid},1},\mathrm{\&Lambda;},{\hat{s}}_{\mathrm{mid},(P-1)}^{*}\&CenterDot;e_{\mathrm{mid},(P-1)})---\left(9\right)$

Wherein, the result by the chip related operation is expressed as:

r＝(r ₀，r ₁，Λ，r _P-1，) (10)

Then, in step 5, carry out chip and merge, the correlated results that step 4 is obtained carries out the chip merging; If the signal indication after correlated results merges is:

d＝(d ₀，d ₁，Λ，d _L-1，) (11)

Get L=P/Q, Q gets the factor of P, as gets 8,16; The chip merge algorithm is:

$d_i=\underset{j=\mathrm{iQ}}{\overset{\mathrm{iQ}+Q-1}{\mathrm{\&Sigma;}}}{r}_j---i=\mathrm{0,1},\mathrm{\&Lambda;},L-1---\left(12\right)$

In step 6, carry out frequency departure and estimate, utilize the phase deviation of the related operation chip amalgamation result of step 5 to calculate frequency deviation;

The phase angle of the relevant amalgamation result of note is:

θ _d＝(θ _d，0，θ _d，1，Λ，θ _d，L-1) (13)

Phase place and frequency departure can have multiple algorithm.

Wherein, method 1: can calculate phase deviation according to following formula:

$\mathrm{\&Delta;\&theta;}=\frac{1}{L-1}\underset{m=1}{\overset{L-1}{\mathrm{\&Sigma;}}}\left(\frac{1}{m}\underset{n=0}{\overset{m-1}{\mathrm{\&Sigma;}}}\left(\frac{{\mathrm{\&theta;}}_{d,m}-{\mathrm{\&theta;}}_{d,n}}{m-n}\right)\right)---\left(14\right)$

Figure 11 is the realization schematic diagram of phase deviation estimation method 1 of the present invention.Calculate the process of phase deviation and can regard Phase-offset (phase deviation) module as.

Method 2: for another method is calculated phase deviation:

$\mathrm{\&Delta;\&theta;}=\frac{1}{\underset{k=1}{\overset{L-1}{\mathrm{\&Sigma;}}}(L-k)\&times;k}\underset{m=1}{\overset{L-1}{\mathrm{\&Sigma;}}}\underset{n=0}{\overset{m-1}{\mathrm{\&Sigma;}}}({\mathrm{\&theta;}}_{d,m}-{\mathrm{\&theta;}}_{d,n})---\left(15\right)$

Figure 12 is seen in the realization of phase deviation estimation method 2.

Therefore, can obtain frequency departure is estimated as:

$\mathrm{\&Delta;f}=\frac{1}{2\mathrm{\&pi;}{T}_{C}Q}\mathrm{\&Delta;\&theta;}---\left(16\right)$

Wherein, T _CIt is the chip width.

By top description, can obtain implement device figure, as shown in figure 13 to whole frequency deviation estimating method to each several part.

Present existing frequency deviation measurement method be utilize according to time in the piece constant channel estimating and the result that obtains of detection algorithm handle, according to court verdict channel variation is estimated near the partial data symbol of channel estimating code, utilize the deviation of estimating to carry out iteration calibration calculation process, transmission data that finally are restored and accurate estimation of deviation.

This method can obtain good frequency deviation measurement result in certain frequency difference scope, its signal-to-noise performance is good.Its limitation is to be unsuitable for big offset frequency situation, and the maximum frequency deviation that can estimate is near 1kHz.And the present invention utilizes channel estimating code rather than data symbol measuring frequency deviation, the most outstanding characteristics are to work in very big frequency departure scope, have expanded slot CDMA greatly or have similarly adopted the estimation range of the terminal frequency deviation of channel estimating code system.

Figure 14 and Figure 15 utilize channel estimating code measuring frequency deviation, and carry out the simulation result of the adjustment of data based on this.

Wherein, the simulated conditions of Figure 14: awgn channel, single user, 8 code channels, SF=16, antenna number is 1, frequency shift (FS) 2000Hz.More do not proofread and correct, proofread and correct and the error rate under each signal to noise ratio when not having frequency deviation with channel estimating code.

The simulated conditions of Figure 15: frequency shift (FS) 1000Hz, other conditions are the same.The error rate when relatively utilizing the channel estimating code correction data and utilizing the data symbol correction data under each signal to noise ratio.

Can see from Figure 14 and Figure 15, be offset with the channel estimating code estimated frequency, and to carry out the adjustment of data in view of the above be effectively, and method of the present invention can not only play a role under the high offset frequency situation that original method (promptly utilize the skew of data symbol estimated frequency, and carry out the adjustment of data in view of the above) lost efficacy; In the frequency deviation region that original method can reach, if frequency shift (FS) is higher, the performance of method of the present invention is also good than original method.

Though described the present invention by embodiment, those of ordinary skills know, the present invention has many distortion and variation and do not break away from spirit of the present invention, therefore, wish that appended claim comprises these distortion and variation and do not break away from spirit of the present invention.

Claims (10)

1. the method for a mobile communication signal frequency deviation measurement comprises step:

Received signal,

Signal to described reception carries out channel estimating, to obtain original estimation result;

According to described original estimation result, recover the fundamental component of reference signal;

Fundamental component and described received signal result relatively according to the reference signal of described recovery obtain frequency departure.

2. the step of the fundamental component of the method for claim 1, wherein described recovery reference signal comprises:

According to pre-defined rule described original estimation result is carried out the finite time decision process, to obtain the locational response of finite time with tap of strong signal;

Utilize channel estimation results after the described finite time decision process to recover the fundamental component of reference signal.

3. the step of the method for claim 1, wherein described acquisition frequency departure comprises:

Carry out relevant to the reference signal fundamental component of recovering with received signal;

Described correlated results is carried out chip to be merged;

The result who utilizes described chip to merge obtains frequency departure.

4. the step that the method for claim 1, wherein described signal to reception carries out channel estimating comprises: the midamble to described received signal partly carries out the response that frequency domain and time domain are handled the acquisition original channel;

The impulse response of original channel satisfies following formula:

$\hat{h}=\mathrm{ifft}(\mathrm{fft}\left(e_{\mathrm{mid}}\right)./\mathrm{fft}\left(m_{\mathrm{basic}}\right))$

Wherein:

The original estimated result of expression channel impulse response, m _BasicBe basic midamble sign indicating number, e _MidBe the midamble part of received signal, fft and ifft represent the inverse operation of rapid fourier change and rapid fourier change respectively.

5. method as claimed in claim 2, wherein, described step of original estimation result being carried out the finite time decision process according to pre-defined rule comprises:

The power of each tap of more described channel response and prearranged signals thresholding;

Keep of the tap of the power of described channel response greater than described prearranged signals thresholding;

The power of putting described channel response is zero less than the tap of described prearranged signals thresholding;

Or

According to predetermined tap number thresholding, the response of the tap of the described predetermined tap number of descending reservation;

Or

Keep of the tap of the signal to noise ratio of described channel response greater than predetermined signal-noise ratio threshold;

The signal to noise ratio of putting described channel response is zero less than the tap of described predetermined signal to noise ratio.

6. method as claimed in claim 2, wherein, the described formula that utilizes channel estimation results after the finite time decision process to recover the reference signal fundamental component is as follows:

${\hat{s}}_{\mathrm{mid}}=\mathrm{ifft}(\mathrm{fft}\left(h^{\&prime;}\right).*\mathrm{fft}\left(m_{\mathrm{basic}}\right))$

Wherein, h ' is the channel estimating after the finite time decision process, m _BasicBe basic midamble sign indicating number,

For utilizing the reference signal fundamental component that channel estimation results recovered after the finite time decision process, fft and ifft represent the inverse operation of rapid fourier change and rapid fourier change respectively.

7. method as claimed in claim 3, wherein, described reference signal fundamental component with recovery is carried out relevant satisfied with received signal:

$r=\mathrm{conj}\left({\hat{s}}_{\mathrm{mid}}\right).*e_{\mathrm{mid}}$

That is: $r=({\hat{s}}_{\mathrm{mid},0}^{*}\&CenterDot;e_{\mathrm{mid},0},{\hat{s}}_{\mathrm{mid},1}^{*}\&CenterDot;e_{\mathrm{mid},1},\mathrm{\&Lambda;},{\hat{s}}_{\mathrm{mid},(P-1)}^{*}\&CenterDot;e_{\mathrm{mid},(P-1)})$

Wherein: computing is gripped in conj () expression altogether; .* represent that data of corresponding positions multiplies each other respectively in two arrays; Be the reference signal fundamental component of recovering, ${\hat{s}}_{\mathrm{mid}}=\{{\hat{s}}_{\mathrm{mid},0},\mathrm{\&Lambda;},{\hat{s}}_{\mathrm{mid},P-1}\};$ e _MidBe received signal, e _Mid={ e _{Mid, 0}, Λ, e _{Mid, P-1}; P=128 is received signal length; R is the result of related operation.

8. method as claimed in claim 3, wherein, the step of correlated results being carried out the chip merging satisfies:

d＝(d ₀，d ₁，Λ，d _L-1，)

$d_i=\underset{j=\mathrm{iQ}}{\overset{\mathrm{iQ}+Q-1}{\mathrm{\&Sigma;}}}{r}_j----i=\mathrm{0,1},\mathrm{\&Lambda;},L-1$

Wherein: L=P/Q is the data length after merging; Q comprises: 4,8,16,32,64 for merging factor; D is the data after merging.

9. method as claimed in claim 3, wherein, the result who utilizes chip to merge, the step that obtains frequency departure comprises:

Obtain phase deviation, satisfy:

$\mathrm{\&Delta;\&theta;}=\frac{1}{L-1}\underset{m=1}{\overset{L-1}{\mathrm{\&Sigma;}}}\left(\frac{1}{m}\underset{n=0}{\overset{m-1}{\mathrm{\&Sigma;}}}\left(\frac{{\mathrm{\&theta;}}_{d,m}-{\mathrm{\&theta;}}_{d,n}}{m-n}\right)\right);$

Or

$\mathrm{\&Delta;\&theta;}=\frac{1}{\underset{k=1}{\overset{L-1}{\mathrm{\&Sigma;}}}(L-k)\&times;k}\underset{m=1}{\overset{L-1}{\mathrm{\&Sigma;}}}\underset{n=0}{\overset{m-1}{\mathrm{\&Sigma;}}}({\mathrm{\&theta;}}_{d,m}-{\mathrm{\&theta;}}_{d,n})$

Wherein: Δ θ obtains phase deviation, θ for asking _{D, i}, i=0 Λ L-1 is for merging the phase place of back data d;

According to the described phase deviation of obtaining, obtain frequency departure, satisfy:

$\mathrm{\&Delta;f}=\frac{1}{2\mathrm{\&pi;}{T}_{C}Q}\&times;\mathrm{\&Delta;\&theta;}$

Wherein: T _CBe the chip width, Δ f is the frequency departure that obtains.

10. the device of the mobile communication signal frequency deviation measurement method of realization such as claim 1-9 comprises:

Receiving system is used to receive mobile communication signal;

Channel estimating apparatus carries out channel estimating to the signal of described reception, to obtain original estimation result;

Judgment device is carried out the finite time decision process according to pre-defined rule to described original estimation result, to obtain the locational response with tap of strong signal of finite time;

Reconstructing device utilizes channel estimating after the described finite time decision process to recover the fundamental component of reference signal;

Relevant apparatus carries out relevant to the fundamental component of recovering reference signal with received signal;

Merge device, described correlated results is carried out chip merge;

The frequency departure deriving means, the result who utilizes described chip to merge obtains frequency departure.

Images