CN105188129A - Synchronization acquisition and tracking method based on multi-angle fractional order related coordination - Google Patents

Abstract

A synchronization acquisition and tracking method based on multi-angle fractional order related coordination relates to the wireless communication field, and is used for realizing the rapid synchronization acquisition and precise synchronous tracking of the synchronous codes. According to the present invention, based on the characteristics that the peak values of the fractional order autocorrelation functions are same and the sharp degrees are different under different rotation angles, according to the system signal parameters and the performance indexes, and by the rotation angles, the fractional order autocorrelation functions of different sharp degrees are selected for the synchronization acquisition and tracking of the communication signal synchronous codes, namely, by the rotation angles, the fractional order correlation functions having relatively wider peak values are selected for the rapid acquisition of the synchronous codes, then the fractional order correlation functions of the more sharp peak values corresponding to the rotation angles are utilized to realize the precise tracking of the synchronous codes. The synchronization acquisition and tracking method based on multi-angle fractional order related coordination is used for the synchronization acquisition and tracking of the synchronous codes in the wireless communication.

Description

To be correlated with collaborative synchronization acquistion and tracking based on multi-angle fractional order

Technical field

The present invention relates to wireless communication field.

Background technology

Be synchronously one of key technology of mobile communication, its objective is that the signal realizing transmitting-receiving two-end acts in agreement in time, it directly affects the quality of communication.Therefore, the problem stablizing, be synchronously reliably, accurately primary solution in communication system how is realized.In digital communication, information flow forms a frame to transmit with one or several code element often.Receiving terminal must know the start/stop time of these frames, otherwise correctly cannot recover information.Synchronous object is exactly the mark of the beginning and end providing frame, sets out this frame at receiving terminal according to these marks.These marks often represent by some special code characters, such as Barker code, PN sequence, Zadoff-Chu sequence etc.

Existing synchronous method, usually based on traditional related operation, normally utilizes the method for setting detection threshold to find the peak value of correlation function to obtain synchronizing information in practical engineering application.In order to improve detection probability and reduce false alarm probability, often require that the correlation function of synchronizing signal has crack characteristic.But due to the impact of channel in testing process, the correlation function of the synchronizing signal calculated not is be a sharp-pointed peak value as expected, so be difficult to accurately to find synchronous.In addition, if need to improve the sample frequency of signal for improving synchronization accuracy, the computing cost of system can greatly be increased like this.

Summary of the invention

The present invention is that Rapid timing acquisition in order to realize synchronous code and precise synchronization are followed the tracks of, thus provides a kind of and to be correlated with collaborative synchronization acquistion and tracking based on multi-angle fractional order.

To be correlated with collaborative synchronization acquistion and tracking based on multi-angle fractional order, it is realized by following steps:

Step one, receiving terminal determination synchronization acquistion parameter, described in catch the anglec of rotation α that parameter comprises fractional order correlator _acq, comparator detection threshold V _ththe variable quantity △ τ of synchronous code phase place is exported with phase search control module _acq;

Meanwhile, receiving terminal determination synchronized tracking parameter, described synchronized tracking parameter comprises the anglec of rotation α of fractional order correlator _tra, phase search control module exports the variable quantity △ τ of synchronous code phase place _trawith the lead and lag amount τ of local synchronization code _tra, and 2 τ _tra≤ T _c; T _cfor symbol width;

Synchronization acquistion process:

Step 2, employing are caught state modulator module and are determined to catch parameter according in step one, and Received signal strength r (t) and local synchronization code are passed through fractional order correlator, and calculating both in the anglec of rotation is α _acqfractional order correlation function peak value V _acq;

Step 3, by the output valve V of step 2 mid-score rank correlator _acqgive threshold compataror, and judge the output valve V of fractional order correlator _acqwhether be less than detection threshold V _th;

Work as V _acqbe less than detection threshold V _thtime, then the phase place of local synchronization code is different with the phase place of the synchronous code received, threshold compataror exports a signal to synchronous code phase search control module, under the control of phase search control module, local synchronization code generator changes the phase state exporting synchronous code, and the variable quantity of synchronous code phase place is △ τ _acq; If the phase state of the local synchronization code after changing is still different from the phase state receiving synchronous code, threshold compataror continues output signal to phase search control module, makes phase search control module change the local phase place with reference to synchronous code again;

Until the local phase state with reference to synchronous code level off to the phase state receiving synchronous code time, the output V of fractional order correlator _acqexceed detection threshold V _th, namely complete the synchronization acquistion of synchronous code, proceed to synchronized tracking process;

Synchronized tracking process:

Step 4, Received signal strength is divided into three tunnels, tracking parameter control module according to tracking parameter determined in step one, by wherein two paths of signals respectively with local advanced code c (the t-τ ' with reference to synchronous code _d+ τ _tra) and delayed code c (t-τ ' _d-τ _tra) to carry out the anglec of rotation be α _trafractional order related operation;

By another road signal and local reference synchronous code c (t-τ ' _d) to carry out the anglec of rotation be α _trafractional order related operation, wherein τ ' _dto the unknown delay volume τ of reception synchronous code _destimated value, after envelope detection, give decision device recover for information data;

Step 5, give adder by the output of lead and lag associated branch in step 4 through envelope detection, produce error signal; And this error signal is carried out filtering through a low pass filter, with the impact of smooth noise on synchronized tracking;

And judge whether this error signal is just, if judged result is yes, then perform step May Day; If judged result is no, then perform step 5 two;

The phase state on step May Day, the then advanced code of local synchronization code than delayed code phase state more convergence receive the phase state of synchronous code, then under the control of phase search control module, the phase state making local synchronization code generator export synchronous code adjusts in advance, and the variable quantity of phase place adjustment is △ τ _tra;

If error signal is just still after adjustment, phase search control module adjusts the local phase place with reference to synchronous code again in advance, until the phase state of the local phase state convergence with reference to synchronous code reception synchronous code, then achieves the synchronized tracking of synchronous code;

The phase state of the delayed code of step 5 two, then local synchronization code than the phase state of advanced code closer to the phase state receiving synchronous code, phase search control module is by local for the delayed adjustment phase place with reference to synchronous code, until the local phase state convergence with reference to synchronous code receives the phase state of synchronous code, then achieve the synchronized tracking of synchronous code.

The present invention is based on the feature that peak value is identical, acuity is different of fractional order auto-correlation function under different rotary angle, the fractional order auto-correlation function selecting acuity different by the anglec of rotation according to system signal parameter and performance index is for the synchronization acquistion of signal of communication synchronous code and tracking, namely select the relatively wide fractional order correlation function of peak value to carry out the fast Acquisition of synchronous code by the anglec of rotation, and then the more sharp-pointed fractional order correlation function of the peak value utilizing the anglec of rotation corresponding is to realize the accurate tracking of synchronous code.With tradition based on compared with the relevant synchronous method of classics, the method clock jitter reduces, and has contribution to signal transacting such as location.In addition, system error performance is had some improvement.

Accompanying drawing explanation

Fig. 1 is the fractional order auto-correlation function emulation schematic diagram of rectangular pulse signal under different rotary angle;

Fig. 2 is the fractional order auto-correlation function emulation schematic diagram of Barker code under different rotary angle;

Fig. 3 is at k=-1, ω ₀when=4, the fractional order auto-correlation function emulation schematic diagram of different rotary angle lower linear FM signal;

Fig. 4 is at q=4, N _zCwhen=7, l=0, the fractional order auto-correlation function emulation schematic diagram of Zadoff-Chu sequence under different rotary angle;

Fig. 5 is synchronic acquisition system principle schematic;

Fig. 6 is synchronous tracking system principle schematic;

Fig. 7 is correlated with based on classics and the error rate of fractional order related synchronization method compares emulation schematic diagram;

Fig. 8 compares emulation schematic diagram based on the fractional order synchronization jitter relevant with classics of being correlated with;

The variance ratio that the synchronized tracking of being correlated with relevant with classics based on fractional order in Fig. 9 is shaken comparatively emulates schematic diagram;

Embodiment

Embodiment one, to be correlated with based on multi-angle fractional order collaborative synchronization acquistion and tracking, it is realized by following steps:

Step one, receiving terminal, according to the anglec of rotation α of the parameter determination synchronization acquistion process mid-score rank correlator of system performance index and selected synchronous code _acq, comparator detection threshold V _ththe variable quantity △ τ of synchronous code phase place is exported with phase search control module _acq; Meanwhile, the anglec of rotation α of synchronized tracking process mid-score rank correlator is determined _tra, phase search control module exports the variable quantity △ τ of synchronous code phase place _trawith the lead and lag amount τ of local synchronization code _tra, and 2 τ _tra≤ T _c.

Step 2, catch state modulator module according in step one determine to catch the effect of parameter under, by Received signal strength r (t) and local synchronization code by fractional order correlator, calculating their angles is α _acqfractional order correlation function peak value V _acq.

Step 3, by the output V of step 2 mid-score rank correlator _acqgive threshold compataror.Work as V _acqbe less than detection threshold V _thtime, the phase place that local synchronization code is described is different with the phase place of the synchronous code received, threshold compataror exports a signal to synchronous code phase search control module, under the effect of phase search control module, local synchronization code generator changes the phase state exporting synchronous code, and the variable quantity of phase place is △ τ _acq.If the phase state of the local synchronization code after changing is still different from the phase state receiving synchronous code, threshold compataror continues output one signal to phase search control module, it is made to change the local phase place with reference to synchronous code again, until during the phase state of the local phase state with reference to synchronous code very close to reception synchronous code, the output V of fractional order correlator _acqexceed detection threshold V _th, namely think the synchronization acquistion achieving synchronous code, thus proceed to synchronized tracking.

Step 4, complete after synchronization acquistion until step 3, Received signal strength be divided into three tunnels, tracking parameter control module according in step one determine the effect of tracking parameter under, wherein two-way respectively with local advanced code c (the t-τ ' with reference to synchronous code _d+ τ _tra) and delayed code c (t-τ ' _d-τ _tra) carry out α _trathe fractional order related operation of angle; Another road and local reference synchronous code c (t-τ ' _d) to carry out angle be α _trafractional order related operation, wherein τ ' _dto the unknown delay volume τ of reception synchronous code _destimation, after envelope detection, give decision device recover for information data.

Step 5, give adder by the output of lead and lag associated branch in step 4 through envelope detection, produce error signal.By error signal through a low pass filter with the impact of smooth noise on synchronized tracking.If error signal is just, illustrate that the phase state of the phase state of the advanced code of local synchronization code than delayed code is closer to the phase state receiving synchronous code, so under the effect of phase search control module, the phase state exporting synchronous code adjusts by local synchronization code generator in advance, and the variable quantity of phase place adjustment is △ τ _tra.If error signal is just still after adjustment, phase search control module adjusts the local phase place with reference to synchronous code again in advance, until the local phase state with reference to synchronous code is very close to the phase state of reception synchronous code.On the contrary, if error signal is negative, illustrate that the phase state of the phase state of the delayed code of local synchronization code than advanced code is closer to the phase state receiving synchronous code, phase search control module is by local for the delayed adjustment phase place with reference to synchronous code, until the local phase state with reference to synchronous code is very close to the phase state of reception synchronous code, namely think the synchronized tracking achieving synchronous code.

Embodiment two, this embodiment are the further restrictions of be correlated with based on multi-angle fractional order collaborative synchronization acquistion and tracking described in embodiment one, in synchronization acquistion process, when Received signal strength and local synchronization code carry out fractional order related operation, the width of fractional order correlation output pulse changes with the change of the anglec of rotation.

Embodiment three, this embodiment are the further restrictions of be correlated with based on multi-angle fractional order collaborative synchronization acquistion and tracking described in embodiment one, in synchronized tracking process, when Received signal strength and local synchronization code carry out fractional order related operation, the width of fractional order correlation output pulse changes with the change of the anglec of rotation.

Embodiment four, this embodiment are the further restrictions of be correlated with based on multi-angle fractional order collaborative synchronization acquistion and tracking described in embodiment one, synchronization acquistion process and synchronized tracking process, the anglec of rotation of fractional order related operation is different.

Embodiment five, this embodiment are the further restrictions of be correlated with based on multi-angle fractional order collaborative synchronization acquistion and tracking described in embodiment two, and the anglec of rotation of fractional order related operation obtains according to system signal parameter and performance Index Calculation.

Embodiment six, this embodiment are the further restrictions of be correlated with based on multi-angle fractional order collaborative synchronization acquistion and tracking described in embodiment three, and the anglec of rotation of fractional order related operation obtains according to system signal parameter and performance Index Calculation.

The frequency power spectrum density Fourier transform pairs each other of correlation function and Fourier transform definition, it is a kind of important method describing signal temporal signatures in classical signal process.In recent years, along with deepening continuously and the continuous expansion of range of application of signal processing theory research, conventional Fourier transform basis emerges series of new signal processing technology, has greatly enriched intension and the extension of classical signal treatment technology.Wherein, fractional fourier transform is as the generalized form of Fourier transform, and it breaches the limitation that Fourier transform can only carry out signal analysis in single time domain or frequency domain, can at the score field treatment and analysis signal between time domain and frequency domain.Compared with Fourier transform, the free parameter of an anglec of rotation that fractional fourier transform is many, along with angle rises to pi/2 continuously from 0, it can show signal tapers to frequency domain all features from time domain.Correspondingly, correlation function (being commonly referred to fractional order correlation function) under fractional fourier transform also presents the expression-form different from traditional correlation function, have the free parameter of an anglec of rotation, it can show the correlation properties of signal under different rotary angle.The fractional order cross-correlation function of two functions x (t) and y (t) is defined as

$R_{xy}^{\mathrm{\α}}\left(\mathrm{\τ}\right)=e^{-{\mathrm{j\τ}}^2\cot \mathrm{\α}}{\∫}_{-\mathrm{\∞}}^{+\mathrm{\∞}}x\left(t\right)y^{*}(t-\mathrm{\τ})e^{jt\mathrm{\τ}\cot \mathrm{\α}}dt---\left(1\right)$

In formula, α corresponds to the anglec of rotation of fractional fourier transform.Especially, as x (t)=y (t), the definition of fractional order auto-correlation function can just be obtained, namely

$R_{xx}^{\mathrm{\α}}\left(\mathrm{\τ}\right)=e^{-{\mathrm{j\τ}}^2\cot \mathrm{\α}}{\∫}_{-\mathrm{\∞}}^{+\mathrm{\∞}}x\left(t\right)x^{*}(t-\mathrm{\τ})e^{jt\mathrm{\τ}\cot \mathrm{\α}}dt---\left(2\right)$

When angle [alpha]=pi/2, fractional order mutually (certainly) correlation function just deteriorates to conventional (certainly) correlation function mutually, namely

$R_{xy}\left(\mathrm{\τ}\right)={\∫}_{-\mathrm{\∞}}^{+\mathrm{\∞}}x\left(t\right)y^{*}(t-\mathrm{\τ})dt---\left(3\right)$

$R_{xx}\left(\mathrm{\τ}\right)={\∫}_{-\mathrm{\∞}}^{+\mathrm{\∞}}x\left(t\right)x^{*}(t-\mathrm{\τ})dt---\left(4\right)$

Therefore, conventional correlation function can regard the special case of fractional order correlation function when angle [alpha]=pi/2 as.

From the angle of Design of Signal, synchronous code mainly can be classified as binary code and permanent zero autocorrelation sequence two class.Such as Barker code, PN code all belong to binary code, can regard the superposition of rectangular pulse as; Permanent zero autocorrelation sequence then mainly contains Zadoff-Chu sequence, and Chirp-like sequence and Frank sequence etc., they are in fact the GCL sequences meeting certain parameter constraints.Based on this, for obtaining vague generalization result, by signal modeling be:

$x\left(t\right)=\frac{1}{\sqrt{{\mathrm{\τ}}_0}}rect\left(\frac{t}{{\mathrm{\τ}}_0}\right)e^{(j/2){\mathrm{kt}}^2+{\mathrm{j\ω}}_{0}t}---\left(5\right)$

In formula, τ ₀>0, k and ω ₀for arbitrary constant, rect (t/ τ ₀) representing rectangular pulse signal, its expression formula is

According to the definition of aforementioned fractional rank auto-correlation function, the fractional order auto-correlation function that can obtain signal x (t) is

$R_{xx}^{\mathrm{\α}}\left(\mathrm{\τ}\right)=e^{-(j/2){\mathrm{\τ}}^2\cot \mathrm{\α}+{\mathrm{j\ω}}_0\mathrm{\τ}}(1-\frac{\left|\mathrm{\τ}\right|}{{\mathrm{\τ}}_0})\sin c\[\frac{\mathrm{\τ}(k+\cot \mathrm{\α}){\mathrm{\τ}}_0}{2\mathrm{\π}}(1-\frac{\left|\mathrm{\τ}\right|}{{\mathrm{\τ}}_0})\]---\left(7\right)$

In formula, | τ |≤τ ₀, sinc ()=sin π ()/π ().

When α=-arccot (k)+n π (n is integer), the auto-correlation function of signal x (t) can abbreviation be

$R_{xx}^{\mathrm{\α}}\left(\mathrm{\τ}\right)=(1-\frac{\left|\mathrm{\τ}\right|}{{\mathrm{\τ}}_0})e^{-(j/2){\mathrm{\τ}}^2\cot \mathrm{\α}+{\mathrm{j\ω}}_0\mathrm{\τ}},\left|\mathrm{\τ}\right|\≤{\mathrm{\τ}}_0---\left(8\right)$

Can find out, the auto-correlation function of signal x (t) is an original frequency is with this understanding ω ₀, chirp rate is the linear FM signal of-cot α, and its envelope modulation function is width is 2 τ ₀triangular pulse signal, therefore the width of the auto-correlation function of x (t) is 2 τ ₀.

As α ≠-arccot (k)+n π, it is ω that the auto-correlation function of signal x (t) is still an original frequency ₀, chirp rate is the linear FM signal of-cot α, but its envelope modulation function is

$(1-\frac{\left|\mathrm{\τ}\right|}{{\mathrm{\τ}}_0})\sin c\[\frac{\mathrm{\τ}(k+\cot \mathrm{\α}){\mathrm{\τ}}_0}{2\mathrm{\π}}(1-\frac{\left|\mathrm{\τ}\right|}{{\mathrm{\τ}}_0})\]---\left(9\right)$

When | τ | < < τ ₀time, envelope is approximately sinc function, namely

$\sin c\&lsqb;\frac{\mathrm{\&tau;}(k+\cot \mathrm{\&alpha;}){\mathrm{\&tau;}}_0}{2\mathrm{\&pi;}}\&rsqb;---\left(10\right)$

When x=pi/2, sinc [x/ π]=2/ π, close-4dB.So, make τ ' (k+cot α) τ ₀/ 2=pi/2, obtains τ '=π/(k+cot α) τ ₀, i.e. wide during the auto-correlation function-4dB of signal x (t) is 2| τ ' |=2 π/(| k+cot α | τ ₀) < < τ ₀.

If k=is ω ₀=0, signal x (t) is rectangular pulse signal; When α=pi/2, its fractional order auto-correlation function is original frequency is 0, and chirp rate is-cot α, envelope modulation function is the linear FM signal of triangular pulse, time wide be 2 τ ₀; And under other α ≠ pi/2 angle, envelope modulation function then becomes sinc function, now during-4dB wide be 2 π/(| cot α | τ ₀) and increase along with α on angle [alpha] principal value interval (0, pi/2) and increase, and [pi/2, π) upper to reduce along with α increase, as shown in Figure 1.Because binary code can regard the superposition of rectangular pulse as, therefore its fractional order auto-correlation function also possesses this characteristic, as shown in Figure 2.In addition, if k ≠ 0, signal x (t) is linear FM signal, and its fractional order auto-correlation function is original frequency when α=-arccot (k)+n π (n is integer) is ω ₀, chirp rate is-cot α, and envelope modulation function is the linear FM signal of triangular pulse, time wide be 2 τ ₀; And under other α ≠-arccot (k)+n π angle, envelope modulation function becomes sinc function, during-4dB wide be 2 π/(| k+cot α | τ ₀) and increase along with α on angle [alpha] principal value interval (0 ,-arccot (k)) and increase, and [-arccot (k), π) upper to reduce along with α increase, as shown in Figure 3.Because permanent zero autocorrelation sequence can regard the Discrete Linear FM signal meeting special parameter condition as, therefore its fractional order auto-correlation function also has such character, as shown in Figure 4.

To sum up analyze, the peak value of the fractional order auto-correlation function of the different rotary angle of a signal is identical, but the correlation rate of decay difference outside peak value, namely the acuity of fractional order auto-correlation function is different.Based on this feature, first can realize Rapid timing acquisition based on the fractional order correlation function that relevant peaks is relatively loose according to system signal parameter and performance index by selecting the suitable anglec of rotation, and then the fractional order correlation function utilizing relevant peaks more sharp-pointed realizes precise synchronization tracking.

The object of synchronization acquistion makes the difference of the phase place of synchronous code in local synchronization code and Received signal strength be less than T _c/ 2 ⁿ, wherein T _cfor symbol width, n is positive integer and its concrete value viewing system accuracy of detection is determined.According to spread spectrum communication theory, slip coherent detection be a kind of the most simply, the most practical synchronization acquiring method.Based in the slip coherent detection of conventional related operation, in order to noise decrease, improve detection probability, the bandwidth after being correlated with by the restriction of system bandwidth is narrow; From shortening capture time, should accelerate sliding speed, namely strengthen send-receive clock difference on the frequency, require that again the bandwidth after being correlated with is wide, both is conflicting.Consider that different rotary angle fractional order auto-correlation function has the advantages that peak value is identical, acuity is different, can anglec of rotation α be passed through _acqcontrol the width that fractional order correlator exports coherent pulse.That is, when sliding fast, suitable angle [alpha] can be selected _acqsystem requirements is met to make the bandwidth after being correlated with.Given this, the slip related synchronization that Fig. 5 gives based on fractional order related operation catches theory diagram.

Once after receiver achieves synchronization acquistion, the local change as far as possible accurately must following the tracks of Received signal strength with reference to synchronous code, make the phase place of local synchronization code little as much as possible with the difference receiving synchronous code phase place, obtain maximum correlation output to fractional order correlator, this process is called synchronized tracking.If observation signal model is r (t)=Ac (t; τ _d)+n (t), 0≤t≤T, wherein n (t) is zero-mean, and power spectral density is N ₀the white Gaussian noise of/2; C (t; τ _d) represent normalized synchronization code signal component in Received signal strength, wherein τ _dfor unknown time delay to be estimated, A is signal amplitude.Noiseless interference and channel delay situation being first discussed, inspiring to therefrom obtaining some.According to the signal detection theory of fractional Fourier transform domain, score field matched filter is to the output c of synchronization code signal _ot () is the fractional order auto-correlation function of c (t), and reach maximum when t=T.That is, score field matched filter exports and reaches maximum sampling time t=T, namely at the peak point of fractional order correlation function.Under noise background, general more difficult to the identification of correlation peak.Assuming that do not sample at peak point, and at t=T-τ _train time, early samples, at t=T+ τ _tratime lag is sampled, amount of delay 2 τ between these two sample points _tra≤ T _c.From the meaning of statistical average, absolute value and the slow absolute value of sampling of early sampling are less than peak value sample value.Because the fractional order auto-correlation function relative optimal sampling moment, t=T was even function, so at t=T-τ _trawith t=T+ τ _trathe absolute value of the fractional order auto-correlation function in moment is equal.With this understanding, suitable sampling time is at t=T-τ _trawith t=T+ τ _trabetween mid point.Based on this, Fig. 6 gives the theory diagram of synchronized tracking.

In figure 6, fractional order correlator instead of the score field matched filter of equivalence.Three fractional order correlators are in mark space T upper integral, and wherein two fractional order correlators do sth. in advance τ than the estimated optimal sampling moment respectively _trawith delay τ _trastart integration, the difference of the absolute value that they export forms error signal.In order to smooth noise is on the impact of tracking performance, by error signal by a low pass filter.If timing off-target sampling time, then the average error signal non-zero that exports of low pass filter, the sign of error then determines phase place that phase search control module exports synchronous code and to lag or in advance.Provide Numerical results below.

Based on Such analysis, using 13 Barker codes as synchronous code, after immediately following through the data message position of 13 Barker code spread spectrums, modulates information mode adopts bipolar modulation.In emulation, each chip carries out 4 samplings, and simulated channel is Gauss's white noise channel.Fig. 7 gives and to be correlated with based on fractional order and the error performance of synchronized algorithm of classical correlation technique compares.Can find out, the synchronous error performance of being correlated with based on fractional order is slightly better than traditional synchronous error performance relevant based on classics, but is more or less the same, this is because the relevant peaks of the classical correlation function of Barker code is inherently very sharp-pointed.Fig. 8 gives signal to noise ratio when being 8dB, the synchronized tracking jitter conditions of two kinds of synchronous method, and in figure, abscissa is 0 expression, there is not synchronization jitter, because each chip has carried out 4 samplings, so 1/4th chips have been shaken in 1 expression, 1/2nd chips have been shaken in 2 expressions; The sign of abscissa then represents respectively to delayed and direction shake in advance.Further, Fig. 9 is base unit with sampling interval, gives the synchronized tracking of being correlated with relevant with classics based on fractional order and shakes the change curve of variance with signal to noise ratio.Can find out, although be more or less the same based on the fractional order synchronous error performance relevant with classics of being correlated with, the former has better synchronous tracking performance, and namely its synchronization jitter is less.

The present invention is based on the feature that peak value is identical, acuity is different of fractional order auto-correlation function under different rotary angle, the fractional order auto-correlation function selecting acuity different by the anglec of rotation according to system signal parameter and performance index is for the synchronization acquistion of signal of communication synchronous code and tracking, namely select the relatively wide fractional order correlation function of peak value to carry out the fast Acquisition of synchronous code by the anglec of rotation, and then the more sharp-pointed fractional order correlation function of the peak value utilizing the anglec of rotation corresponding is to realize the accurate tracking of synchronous code.With tradition based on compared with the relevant synchronous method of classics, the method clock jitter reduces, and has contribution to signal transacting such as location.In addition, system error performance is had some improvement.

Claims (7)

1. to be correlated with collaborative synchronization acquistion and tracking based on multi-angle fractional order, to it is characterized in that: it is realized by following steps:

Step one, receiving terminal determination synchronization acquistion parameter, described in catch the anglec of rotation α that parameter comprises fractional order correlator _acq, comparator detection threshold V _ththe variation delta τ of synchronous code phase place is exported with phase search control module _acq;

Meanwhile, receiving terminal determination synchronized tracking parameter, described synchronized tracking parameter comprises the anglec of rotation α of fractional order correlator _tra, phase search control module exports the variation delta τ of synchronous code phase place _trawith the lead and lag amount τ of local synchronization code _tra, and 2 τ _tra≤ T _c; T _cfor symbol width;

Synchronization acquistion process:

Step 2, employing are caught state modulator module and are determined to catch parameter according in step one, and Received signal strength r (t) and local synchronization code are passed through fractional order correlator, and calculating both in the anglec of rotation is α _acqfractional order correlation function peak value V _acq;

Step 3, by the output valve V of step 2 mid-score rank correlator _acqgive threshold compataror, and judge the output valve V of fractional order correlator _acqwhether be less than detection threshold V _th;

Work as V _acqbe less than detection threshold V _thtime, then the phase place of local synchronization code is different with the phase place of the synchronous code received, threshold compataror exports a signal to synchronous code phase search control module, under the control of phase search control module, local synchronization code generator changes the phase state exporting synchronous code, and the variable quantity of synchronous code phase place is Δ τ _acq; If the phase state of the local synchronization code after changing is still different from the phase state receiving synchronous code, threshold compataror continues output signal to phase search control module, makes phase search control module change the local phase place with reference to synchronous code again;

Until the local phase state with reference to synchronous code level off to the phase state receiving synchronous code time, the output V of fractional order correlator _acqexceed detection threshold V _th, namely complete the synchronization acquistion of synchronous code, proceed to synchronized tracking process;

Synchronized tracking process:

Step 4, Received signal strength is divided into three tunnels, tracking parameter control module according to tracking parameter determined in step one, by wherein two paths of signals respectively with local advanced code c (the t-τ ' with reference to synchronous code _d+ τ _tra) and delayed code c (t-τ ' _d-τ _tra) to carry out the anglec of rotation be α _trafractional order related operation;

By another road signal and local reference synchronous code c (t-τ ' _d) to carry out the anglec of rotation be α _trafractional order related operation, wherein τ ' _dto the unknown delay volume τ of reception synchronous code _destimated value, after envelope detection, give decision device recover for information data;

Step 5, give adder by the output of lead and lag associated branch in step 4 through envelope detection, produce error signal; And this error signal is carried out filtering through a low pass filter, with the impact of smooth noise on synchronized tracking;

And judge whether this error signal is just, if judged result is yes, then perform step May Day; If judged result is no, then perform step 5 two;

The phase state on step May Day, the then advanced code of local synchronization code than delayed code phase state more convergence receive the phase state of synchronous code, then under the control of phase search control module, the phase state making local synchronization code generator export synchronous code adjusts in advance, and the variable quantity of phase place adjustment is Δ τ _tra;

If error signal is just still after adjustment, phase search control module adjusts the local phase place with reference to synchronous code again in advance, until the phase state of the local phase state convergence with reference to synchronous code reception synchronous code, then achieves the synchronized tracking of synchronous code;

The phase state of the delayed code of step 5 two, then local synchronization code than the phase state of advanced code closer to the phase state receiving synchronous code, phase search control module is by local for the delayed adjustment phase place with reference to synchronous code, until the local phase state convergence with reference to synchronous code receives the phase state of synchronous code, then achieve the synchronized tracking of synchronous code.

2. to be according to claim 1ly correlated with collaborative synchronization acquistion and tracking based on multi-angle fractional order, to it is characterized in that in step one, receiving terminal determination synchronization acquistion parameter determines according to the parameter of system performance index and selected synchronous code.

3. to be according to claim 1ly correlated with collaborative synchronization acquistion and tracking based on multi-angle fractional order, it is characterized in that in synchronization acquistion process, when Received signal strength and local synchronization code carry out fractional order related operation, the width of fractional order correlation output pulse changes with the change of the anglec of rotation.

4. to be according to claim 1ly correlated with collaborative synchronization acquistion and tracking based on multi-angle fractional order, it is characterized in that in synchronized tracking process, when Received signal strength and local synchronization code carry out fractional order related operation, the width of fractional order correlation output pulse changes with the change of the anglec of rotation.

5. to be according to claim 1ly correlated with collaborative synchronization acquistion and tracking based on multi-angle fractional order, it is characterized in that synchronization acquistion process and synchronized tracking process, the anglec of rotation of fractional order related operation is different.

6. to be according to claim 3ly correlated with collaborative synchronization acquistion and tracking based on multi-angle fractional order, it is characterized in that, the anglec of rotation of fractional order related operation obtains according to system signal parameter and performance Index Calculation.

7. to be according to claim 4ly correlated with collaborative synchronization acquistion and tracking based on multi-angle fractional order, it is characterized in that, the anglec of rotation of fractional order related operation obtains according to system signal parameter and performance Index Calculation.