CN102469574B - Based on the time synchronization method of time-domain received signal and device in a kind of LTE system - Google Patents

Abstract

The invention discloses in a kind of LTE system based on the time synchronization method of time-domain received signal and device, the method comprises: step one, downlink reception termination in LTE system is received and is stored and is used for Cell searching and synchronous time-domain signal sequence, Received signal strength is designated as y (i), i=0,1 ... T-1, wherein T is the sampling number of the Received signal strength in length detection time; Step 2, carries out slip mirror image and is correlated with, obtain mirror image correlated results by Received signal strength y (i); Step 3, judges whether to there is obvious peak value interval according to the absolute value of mirror image correlated results, if exist, then completes catching of master sync signal, and finds the position acquisition timing information of maximum correlation peak according to the absolute value of correlated results; Otherwise return step one.The present invention utilizes the slip of the mirror image of Received signal strength to be correlated with and detects, and do not need to carry out related operation respectively to three groups of PSS, implementation complexity is low, accuracy is high.

Description

Based on the time synchronization method of time-domain received signal and device in a kind of LTE system

Technical field

The invention belongs to communication technical field, relate in a kind of LTE system based on the time synchronization method of time-domain received signal and device.

Background technology

Mobile subscriber, when accessing community, first will carry out signal scanning, determine whether there is the downstream signal that whether there is available cell in available frequency band and available frequency band in the frequency range that network allows use.In LTE system, cell base station sends every the cycle of 5ms the master sync signal (PrimarySynchronizationSignal, PSS) that is carried cell identification number.Whether first mobile subscriber detects PSS at the initial stage of Cell searching exists, if detect, it exists, then confirm as and can use frequency range, carry out the Time and Frequency Synchronization of cell identification and downstream signal, otherwise, continue to detect, until the descending master sync signal that can use in frequency range detected.

The PSS of LTE system is generated by ZC sequence, has three groups of different sequences available.Due at cell search phase, which group PSS base station specifically have sent is blind to user, therefore, traditional timing method based on PSS is, first user prestores three groups of local PSS sequences, and then often organizing PSS, to carry out slip to Received signal strength respectively relevant, when obvious correlation peak being detected, determine PSS to be detected, and find timing synchronization position at peak.Such process has a problem, is exactly that three groups of related operation complexities are high, is unfavorable for quick obtaining timing information.In addition, if user is in synchronizing network, when adopting local synchronization sequence relevant with receiving sequence, formation is disturbed this cell received signal by the synchronizing signal that other communities send.

Therefore, prior art needs to carry out related operation respectively to three groups of PSS, and process operand is large, is unfavorable for quick obtaining synchronizing information, and extends user and detect and the available frequency band time that downstream signal transmits add the time required for Cell searching.

Summary of the invention

Technical problem to be solved by this invention is: provide the time synchronization method based on time-domain received signal in a kind of LTE system;

In addition, the present invention also provides the timing synchronization device based on time-domain received signal in a kind of LTE system.

For solving the problems of the technologies described above, the present invention adopts following technical scheme.

Based on a time synchronization method for time-domain received signal in LTE system, comprising:

Step one, the downlink reception termination in LTE system is received and is stored and is used for Cell searching and synchronous time-domain signal sequence, Received signal strength is designated as y (i), i=0,1 ..., T-1, wherein T is the sampling number of the Received signal strength in length detection time;

Step 2, carries out slip mirror image and is correlated with, obtain mirror image correlated results by Received signal strength y (i); The concrete mode that described slip mirror image is relevant is

$r\left(i\right)=\underset{k=1}{\overset{\frac{N-2}{2}}{\Σ}}y(i+\frac{N-2}{2}+k)y^{*}(i+\frac{N-2}{2}-k)$

Or

$r\left(i\right)=\underset{k=1}{\overset{\frac{N-2}{2}}{\Σ}}{y}^{*}(i+\frac{N-2}{2}+k)y(i+\frac{N-2}{2}-k),$

Wherein, i=0,1,, T-1, N are the FFT length for Cell searching and synchronous Received signal strength y (i) that downlink reception termination in LTE system is received, k is the index number of summation operation, and subscript * represents complex conjugate, and r (i) is mirror image correlated results;

Step 3, judges whether to there is obvious peak value interval according to the absolute value of mirror image correlated results, if exist, then completes catching of master sync signal, and finds the position acquisition timing information of maximum correlation peak according to the absolute value of correlated results; Otherwise return step one.

Based on a timing synchronization device for time-domain received signal in LTE system, comprise memory module, slip mirror image correlation module, SNR detection module; Described memory module in order to store that downlink reception termination in LTE system receives for Cell searching and synchronous Received signal strength; Described slip mirror image correlation module is connected with described memory module, in order to carry out slip mirror image relevant treatment to described Received signal strength, obtains mirror image correlated results; Described SNR detection module is connected with described slip mirror image correlation module, in order to find the position acquisition timing information of maximum correlation peak according to the absolute value of described mirror image correlated results, completes the synchronous of receiving terminal and base station.

As a preferred embodiment of the present invention, the model of described slip mirror image correlation module is:

$r\left(i\right)=\underset{k=1}{\overset{\frac{N-2}{2}}{\Σ}}y(i+\frac{N-2}{2}+k)y^{*}(i+\frac{N-2}{2}-k)$

Or

$r\left(i\right)=\underset{k=1}{\overset{\frac{N-2}{2}}{\Σ}}{y}^{*}(i+\frac{N-2}{2}+k)y(i+\frac{N-2}{2}-k),$

Wherein, r (i) is mirror image correlated results, i=0,1 ..., T-1; T is the sampling number of the Received signal strength in length detection time; N is the FFT length for Cell searching and synchronous Received signal strength y (i) that downlink reception termination in LTE system is received, and k is the index number of summation operation, and subscript * represents complex conjugate.

Beneficial effect of the present invention is: the present invention utilizes the slip of the mirror image of Received signal strength to be correlated with and detects, and do not need to carry out related operation respectively to three groups of PSS, implementation complexity is low; Meanwhile, owing to being related operation own to received signal, the synchronizing signal of other communities in synchronizing network becomes useful signal to this community, can improve the accuracy of timing.

Accompanying drawing explanation

Fig. 1 is the flow chart based on the time synchronization method of time-domain received signal in LTE system of the present invention;

Fig. 2 is 64 OFDM time domain receiving symbol sequences described in embodiment two;

Fig. 3 is the mirror image accompanying drawings of 64 OFDM time domain receiving symbol sequences described in embodiment two;

Fig. 4 is the timing synchronization device structural representation based on time-domain received signal in LTE system of the present invention.

Embodiment

For the problems referred to above, the present invention is based on the specular characteristic of ZC sequence, propose to use time-domain received signal to carry out the method and apparatus of Timing Synchronization.First the method receives time-domain signal in the frequency range that network allows use, then carries out mirror image to received signal and slides relevant, whether there is obvious peak value carry out Timing Synchronization by detection.

Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described in further detail.

Embodiment one

The present embodiment provides the time synchronization method based on time-domain received signal in a kind of LTE system, and the flow chart of the method as shown in Figure 1, specifically comprises:

(1) Received signal strength stores.

Downlink reception termination harvesting storage in LTE system is used for Cell searching and synchronous time-domain signal sequence, and this Received signal strength is designated as y (i), i=0,1 ..., T-1, wherein T is the Received signal strength sampling number in length detection time.

(2) slip mirror image is correlated with.

Received signal strength y (i) is carried out slip mirror image to be correlated with, relevant way is as follows:

$r\left(i\right)=\underset{k=1}{\overset{\frac{N-2}{2}}{\Σ}}y(i+\frac{N-2}{2}+k)y^{*}(i+\frac{N-2}{2}-k),i=0,1,...,T-1$

Or

$r\left(i\right)=\underset{k=1}{\overset{\frac{N-2}{2}}{\Σ}}{y}^{*}(i+\frac{N-2}{2}+k)y(i+\frac{N-2}{2}-k),i=0,1,...,T-1$

Wherein, N is downlink reception end in LTE system for the FFT length of Cell searching and synchronous OFDM, and k is the index number of summation operation, and subscript " * " represents complex conjugate, and r (i) is i-th mirror image correlation.Above-mentioned two kinds of correlation forms are of equal value in essence, for simplicity's sake, in description below, adopt the first form.

(3) correlation peak judges.

Judge whether to there is obvious peak value interval according to the absolute value of r (i), if exist, then complete catching of master sync signal, and find the position acquisition timing information of maximum correlation peak according to the absolute value of r (i); Otherwise continue in this frequency range, detect or be switched to miscellaneous stipulations frequency range to detect, repeat above-mentioned testing process.

Mobile subscriber is in the process of access community, first to determine whether base station has downstream signal in available frequency band and to carry out signal synchronous, the present invention is according to the specular feature of LTE system master sync signal, slide relevant by carrying out mirror image to time-domain received signal, obtain the time synchronization method not relying on local PSS, the method implementation complexity is low.

Embodiment two

The present embodiment provides the timing synchronization device based on time-domain received signal in a kind of LTE system, and the structure of this device as shown in Figure 4, comprises memory module, slip mirror image correlation module, SNR detection module; Described memory module in order to store that downlink reception termination in LTE system receives for Cell searching and synchronous Received signal strength; Described slip mirror image correlation module is connected with described memory module, in order to carry out slip mirror image relevant treatment to described Received signal strength, obtains mirror image correlated results; Described SNR detection module is connected with described slip mirror image correlation module, in order to find the position acquisition timing information of maximum correlation peak according to the absolute value of described mirror image correlated results, completes the synchronous of receiving terminal and base station.Wherein the model of slip mirror image correlation module is:

$r\left(i\right)=\underset{k=1}{\overset{\frac{N-2}{2}}{\Σ}}y(i+\frac{N-2}{2}+k)y^{*}(i+\frac{N-2}{2}-k)$

Or

$r\left(i\right)=\underset{k=1}{\overset{\frac{N-2}{2}}{\Σ}}{y}^{*}(i+\frac{N-2}{2}+k)y(i+\frac{N-2}{2}-k),$

Wherein, r (i) is mirror image correlated results, i=0,1 ..., T-1; T is the sampling number of the Received signal strength in length detection time; N is the FFT length for Cell searching and synchronous Received signal strength y (i) that downlink reception termination in LTE system is received, and k is the index number of summation operation, and subscript * represents complex conjugate.

Embodiment three

The present embodiment is the specific implementation process of method described in embodiment one, wherein, and the FFT computing that Cell searching adopts N=64 point OFDM to receive.

Suppose that the receiving sequence for Cell searching stored after user starts to receive data is y (i), i=0,1 ... ..9600-1, i.e. T=9600, be equivalent to the data that receiving terminal stores a radio frames in 10ms.Following computing is carried out to sequences y (i) and obtains correlated series value r (i):

$r\left(i\right)=\underset{k=1}{\overset{31}{\Σ}}y(i+31+k)y^{*}(i+31-k),i=0,1,\mathrm{.....9600}-1$

The time domain symbol sequence of 64 OFDM symbol length that Fig. 2 provides.For i=1, carry out mirror image related operation, be equivalent to y (32) for symmetrical centre, y (32) two edge lengths is the summation of the conjugate multiplication of the symmetric points of 31, as shown in Figure 3.

According to the specular characteristic of time domain PSS signal, when participating in the relevant two parts sequences y (i+31+k) of slip and y (i+31-k) is the receiving sequence sending PSS signal, there will be larger relevant peaks; Otherwise this two parts sequence is the Received signal strength of random noise, user data or other control signals.Because the Received signal strength of random noise, user data or other control signals does not generally possess the characteristic of specular, therefore occur that the probability of peak value is very little.

Here description of the invention and application is illustrative, not wants by scope restriction of the present invention in the above-described embodiments.Distortion and the change of embodiment disclosed are here possible, are known for the replacement of embodiment those those of ordinary skill in the art and the various parts of equivalence.Those skilled in the art are noted that when not departing from spirit of the present invention or substantive characteristics, and the present invention with other forms, structure, layout, ratio, and can realize with other elements, material and parts.

Claims (2)

1. in LTE system based on a time synchronization method for time-domain received signal, it is characterized in that, described time synchronization method comprises:

Step one, the downlink reception termination in LTE system is received and is stored and is used for Cell searching and synchronous time-domain signal sequence, Received signal strength is designated as y (i), i=0,1 ..., T-1, wherein T is the sampling number of the Received signal strength in length detection time;

Step 2, carries out slip mirror image and is correlated with, obtain mirror image correlated results by Received signal strength y (i); The concrete mode that described slip mirror image is relevant is

$r\left(i\right)=\underset{k=1}{\overset{\frac{N-2}{2}}{\Σ}}y(i+\frac{N-2}{2}+k)y^{*}(i+\frac{N-2}{2}-k)$

Or

$r\left(i\right)=\underset{k=1}{\overset{\frac{N-2}{2}}{\Σ}}{y}^{*}(i+\frac{N-2}{2}+k)y(i+\frac{N-2}{2}-k),$

Wherein, i=0,1,, T-1, N are the FFT length for Cell searching and synchronous Received signal strength y (i) that downlink reception termination in LTE system is received, k is the index number of summation operation, and subscript * represents complex conjugate, and r (i) is mirror image correlated results;

Step 3, judges whether to there is obvious peak value interval according to the absolute value of mirror image correlated results, if exist, then completes catching of master sync signal, and finds the position acquisition timing information of maximum correlation peak according to the absolute value of correlated results; Otherwise return step one.

2. in LTE system based on a timing synchronization device for time-domain received signal, it is characterized in that: described timing synchronization device comprises memory module, slip mirror image correlation module, SNR detection module; Described memory module in order to store that downlink reception termination in LTE system receives for Cell searching and synchronous Received signal strength; Described slip mirror image correlation module is connected with described memory module, in order to carry out slip mirror image relevant treatment to described Received signal strength, obtains mirror image correlated results; Described SNR detection module is connected with described slip mirror image correlation module, in order to find the position acquisition timing information of maximum correlation peak according to the absolute value of described mirror image correlated results, completes the synchronous of receiving terminal and base station; The model of described slip mirror image correlation module is:

$r\left(i\right)=\underset{k=1}{\overset{\frac{N-2}{2}}{\Σ}}y(i+\frac{N-2}{2}+k)y^{*}(i+\frac{N-2}{2}-k)$

Or

$r\left(i\right)=\underset{k=1}{\overset{\frac{N-2}{2}}{\Σ}}{y}^{*}(i+\frac{N-2}{2}+k)y(i+\frac{N-2}{2}-k),$

Wherein, r (i) is mirror image correlated results, i=0,1 ..., T-1; T is the sampling number of the Received signal strength in length detection time; N is the FFT length for Cell searching and synchronous Received signal strength y (i) that downlink reception termination in LTE system is received, and k is the index number of summation operation, and subscript * represents complex conjugate.