WO2017036325A1

WO2017036325A1 - Signal synchronization method and device

Info

Publication number: WO2017036325A1
Application number: PCT/CN2016/096392
Authority: WO
Inventors: 王铠尧; 刘永俊; 钟怡
Original assignee: 华为技术有限公司
Priority date: 2015-09-02
Filing date: 2016-08-23
Publication date: 2017-03-09
Also published as: CN106487494B; CN106487494A

Abstract

Embodiments of the present invention provide a signal synchronization method and device, the method comprising: performing coprime sampling on a first synchronization sequence stored locally to obtain a first sampled sequence; determining, according to a second synchronization sequence included in a synchronization signal transmitted by a base station, a plurality of short sequences; performing coprime sampling respectively on the plurality of short sequences to obtain a plurality of second sampled sequences; and if a peak value in a first set of correlation values obtained from cross-correlation computation between the first sampled sequence and the plurality of second sampled sequences is greater than a first predetermined threshold, using a position of the second synchronization sequence corresponding to the peak value in the first set of correlation values as an initial position to perform synchronization with the base station. In embodiments of the present invention, cross-correlation computation is performed on sequences obtained from performing coprime sampling respectively on a local synchronization sequence and a received synchronization sequence, to determine an initial position to perform synchronization with a base station, thereby reducing computational complexity.

Description

Signal synchronization method and signal synchronization device

The present application claims priority to Chinese Patent Application No. 201510555847.0, entitled "Signal Synchronization Method and Signal Synchronization Device", filed on September 2, 2015, the entire contents of which are incorporated herein by reference. In the application.

Technical field

The present invention relates to the field of communications and, more particularly, to a method of signal synchronization and a device for signal synchronization.

Background technique

The mobile terminal needs to access the base station to communicate with the base station, and needs to synchronize with the base station. Symbol timing synchronization is the first step in the mobile terminal performing a cell search to achieve the synchronization process. In a general communication system, the specific position of the bit synchronization or frame synchronization can be obtained by a good autocorrelation property of the bit synchronization sequence or the frame synchronization sequence. Similarly, in the Long Term Evolution (LTE) system, the location of symbol timing synchronization can also be obtained based on the autocorrelation property of the synchronization sequence.

In the Long Term Evolution-Machine-To-Machine (LTE-M) system, an efficient and accurate timing synchronization algorithm is the key to ensure that mobile terminals can quickly access the cell. In the existing LTE-M system, the mobile terminal can implement timing synchronization by using the following method: the mobile terminal receives the synchronization sequence sent by the base station, and performs a difference operation on the synchronization sequence to obtain a sequence after the difference is solved; then, the mobile terminal uses the local storage. The sequence performs sliding correlation on the sequence after the difference and obtains the correlation peak from the obtained correlation value; then, the position of the symbol timing synchronization is determined by judging the correlation peak and the preset frame detection threshold. When the correlation peak is greater than the frame detection threshold, the position corresponding to the correlation peak can be used as the starting position of the synchronization signal, and the completion symbol is synchronized. When the correlation peak is less than or equal to the frame detection threshold, the mobile terminal may re-search for the synchronization information to access the cell again.

However, since the number of data points receiving the synchronization sequence is determined by the bandwidth, the larger the bandwidth, the larger the number of data points. Moreover, the sampling rate (eg, 240 Ksps) of the synchronization algorithm in the system can be a multiple (eg, 20 times) symbol rate. Therefore, the timing of the sampling point sliding range is very large. In this way, the mobile terminal needs to detect all the received data points, and the calculation amount is large, and the operation complexity is high.

Summary of the invention

Embodiments of the present invention provide a method for signal synchronization and a device for synchronizing signals, which can reduce computational complexity.

In a first aspect, a method for signal synchronization is provided, comprising: performing a mutual sampling on a first synchronization sequence to obtain a first sampling sequence, wherein the first synchronization sequence is stored in a mobile terminal, and the mutual sampling is The sequence is sampled uniformly using two prime numbers; the second synchronization sequence carried by the synchronization signal sent by the base station is subjected to a difference operation to obtain a solution sequence; and the length of the solution is preset to be a preset value. a third sequence; downsampling the plurality of third sequences to obtain a plurality of fourth sequences, wherein a length of each fourth sequence is the same as a length of the first synchronization sequence; Performing the mutual sampling on the four sequences to obtain a plurality of second sampling sequences; performing a cross-correlation operation on each of the first sampling sequence and each of the plurality of second sampling sequences to obtain a first a set of correlation values, wherein the cross-correlation operation is a sliding dot product with respect to time between two sequences, the first set of correlation values being used to represent the first sample sequence and respectively Correlating the correlation of each second sampling sequence; comparing a peak of the first set of correlation values with a first preset threshold; when a peak of the first set of correlation values is greater than the first pre- When the threshold is set, the position of the second synchronization sequence corresponding to the peak of the first set of correlation values in the synchronization signal is used as a starting position for synchronizing signals with the base station.

With reference to the first aspect, in an implementation manner of the first aspect, a length p of the first synchronization sequence, a length q of the first sampling sequence, and two prime numbers M and N of the mutual sampling are satisfied :

In conjunction with the first aspect and the foregoing implementation manner, in another implementation manner of the first aspect, the method further includes: when a peak value of the first group of correlation values is less than or equal to the first preset threshold And performing a cross-correlation operation on the first remaining sequence and the plurality of second remaining sequences respectively to obtain a second set of correlation values, wherein the first remaining sequence is to perform coprime on the locally stored first synchronization sequence a sequence remaining after sampling, the second remaining sequence is a sequence remaining after the mutual sampling of the fourth sequence, and the second group of correlation values is used to represent the first remaining sequence and each second Correlation of the remaining sequence; adding the first set of correlation values and the second set of correlation values to obtain a third set of correlation values, the third set of correlation values being used to indicate that the first synchronization sequence is respectively Correlation degree of each of the fourth sequences; selecting a maximum value from the third group of correlation values to determine a third group phase a peak value of the threshold value; when the peak value of the third group correlation value is greater than the second preset threshold value, the position of the second synchronization sequence corresponding to the peak value of the third group correlation value is used as synchronization with the base station The starting position.

A second aspect provides an apparatus for synchronizing signals, including: a first inter-prime sampling unit, configured to perform mutual quality sampling on a first synchronization sequence to obtain a first sampling sequence, where the first synchronization sequence is stored in In the mobile terminal, the mutual quality sampling is to separately sample the sequence by using two prime numbers, and the de-differential unit is configured to perform a difference operation on the second synchronization sequence carried by the synchronization signal sent by the base station to obtain a solution sequence; An intercepting unit, configured to intercept, from the solution difference sequence obtained by the solution difference unit, a plurality of third sequences having a preset length; and a downsampling unit, configured to obtain the multiple third sequences obtained by the intercepting unit Performing downsampling separately to obtain a plurality of fourth sequences, wherein each fourth sequence has the same length as the first synchronization sequence; and a second prime sampling unit is configured for the downsampling unit Performing the mutual sampling on the plurality of fourth sequences to obtain a plurality of second sampling sequences; the first cross-correlation operation unit, configured to obtain the first sampling unit Performing a cross-correlation operation on each of the plurality of second sampling sequences obtained by the sampling sequence and the second inter-sample unit to obtain a first set of correlation values, wherein the cross-correlation operation a sliding dot product with respect to time between two sequences, the first set of correlation values being used to indicate the correlation between the first sample sequence and each of the second sample sequences; a comparison unit for The peak value of the first group of correlation values obtained by the first cross-correlation operation unit is compared with a first preset threshold value; the first synchronization unit is configured to be used by the cross-correlation operation unit When the peak value of the set of correlation values is greater than the first preset threshold value, the position of the second synchronization sequence corresponding to the peak value of the first set of correlation values in the synchronization signal is taken as The starting position of the base station to achieve signal synchronization.

With reference to the second aspect, in an implementation manner of the second aspect, the length p of the first synchronization sequence, the length q of the first sampling sequence, and the two prime numbers M and N of the mutual sampling should satisfy :

With reference to the second aspect and the foregoing implementation manner, in another implementation manner of the second aspect, the apparatus further includes: a second cross-correlation operation unit, configured to: when a peak value of the first group of correlation values is less than or When the first preset threshold is equal to the first preset sequence, the first remaining sequence is respectively subjected to a cross-correlation operation with the plurality of second remaining sequences to obtain a second set of correlation values, wherein the first remaining sequence is for the local a sequence remaining after the stored first synchronization sequence is subjected to mutual sampling, and the second remaining sequence is a sequence remaining after the mutual sampling of the fourth sequence, wherein the second set of correlation values is used to indicate the correlation between the first remaining sequence and each of the second remaining sequences; Adding a first set of correlation values and the second set of correlation values to obtain a third set of correlation values, the third set of correlation values being used to represent the first synchronization sequence and each of the fourth sequences a correlation unit, configured to determine, from the third set of correlation values, a maximum value as a peak value of the third group of correlation values; and a second synchronization unit, configured to: when the third group of correlation values has a peak value greater than a second When the threshold is preset, the position of the second synchronization sequence corresponding to the peak of the third group of correlation values is taken as the starting position synchronized with the base station.

A third aspect provides a mobile terminal, including: a memory, a receiver, and a processor; the memory is configured to store an instruction executed by the processor; and the processor is configured to control the receiver to receive a synchronization sent by a base station a second synchronization sequence carried by the signal; the processor is further configured to perform mutual sampling on the first synchronization sequence to obtain a first sampling sequence, and perform a difference operation on the second synchronization sequence to obtain a solution sequence, from the solution And the plurality of third sequences are respectively downsampled to obtain a plurality of fourth sequences, and the plurality of fourth sequences are respectively subjected to the mutual sampling. Obtaining a plurality of second sampling sequences, performing a cross-correlation operation on each of the first sampling sequence and each of the plurality of second sampling sequences to obtain a first set of correlation values, and the first The peak value in the group correlation value is compared with the first preset threshold value, and when the peak value in the first group correlation value is greater than the first preset threshold value, Peak Corresponding position of the second synchronization sequence in the synchronization signal as a starting position for synchronizing signals with the base station, wherein the first synchronization sequence is stored in a mobile terminal, and the mutual quality sampling is using two The prime numbers are uniformly sampled at intervals, and the length of each fourth sequence is the same as the length of the first synchronization sequence, and the cross-correlation operation is a sliding dot product with respect to time between two sequences. The first set of correlation values is used to indicate the correlation of the first sample sequence with each of the second sample sequences.

With reference to the third aspect, in an implementation manner of the third aspect, the length p of the first synchronization sequence, the length q of the first sampling sequence, and the two prime numbers M and N of the mutual sampling should satisfy :

In combination with the third aspect and the foregoing implementation manner, in another implementation manner of the third aspect, the processor is further configured to: when a peak of the first group of correlation values is less than or equal to the first preset gate When the limit value is obtained, the first remaining sequence and the plurality of second remaining sequences are respectively subjected to cross-correlation operation, thereby obtaining a second set of correlation values, adding the first set of correlation values and the second set of correlation values to obtain a third set of correlation values, and selecting a maximum value from the third set of correlation values to determine a third set of correlation values a peak value, when a peak value of the third group correlation value is greater than a second preset threshold value, a position of a second synchronization sequence corresponding to a peak value of the third group correlation value is used as a synchronization with the base station a first position, wherein the first remaining sequence is a sequence remaining after the first synchronization sequence of the locally stored first synchronization sequence, and the second remaining sequence is after the mutual sampling of the fourth sequence a sequence of the second set of correlation values used to represent the correlation of the first remaining sequence and each of the second remaining sequences, the third set of correlation values being used to represent the first synchronization sequence respectively and each The relevance of the fourth sequence.

In the embodiment of the present invention, the local synchronization sequence and the synchronization sequence sent by the base station are both subjected to mutual sampling, and the starting position of synchronization with the base station is determined according to the cross-correlation operation result of the sequence after the mutual sampling. In this way, the technical problem of directly calculating the cross-correlation operation between the local synchronization sequence and the pre-sampling pre-sampling sequence to determine the synchronization start position is high, and the computational complexity can be reduced.

DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings to be used in the embodiments of the present invention will be briefly described below. It is obvious that the drawings described below are only some embodiments of the present invention, Those skilled in the art can also obtain other drawings based on these drawings without paying any creative work.

1 is a schematic flow chart of a synchronization method according to an embodiment of the present invention.

FIG. 2 is a schematic flowchart of a synchronization method according to another embodiment of the present invention.

Figure 3 is a block diagram of a synchronization device in accordance with one embodiment of the present invention.

4 is a block diagram of a synchronization device according to another embodiment of the present invention.

detailed description

The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are a part of the embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of the present invention.

A mobile terminal in the embodiment of the present invention may be referred to as a user equipment. (User Equipment, abbreviated as "UE"), terminal (Terminal), mobile station (Mobile Station, abbreviated as "MS"), and the like. The mobile terminal can be a mobile phone (or "cellular" phone) or a computer with a mobile terminal, such as a portable, pocket, handheld, computer built-in or in-vehicle mobile device.

1 is a schematic flow chart of a synchronization method according to an embodiment of the present invention. The method of Figure 1 can be performed by a mobile terminal.

Step 101: Perform mutual quality sampling on the first synchronization sequence to obtain a first sampling sequence, where the first synchronization sequence is stored in the mobile terminal, and the mutual quality sampling is to uniformly sample the sequence using two prime numbers.

Step 102: Perform a difference operation on the second synchronization sequence carried by the synchronization signal sent by the base station to obtain a solution sequence.

103. Intercept a plurality of third sequences whose data length is a preset value from the solution sequence.

104. Downsample a plurality of third sequences to obtain a plurality of fourth sequences, wherein each fourth sequence has the same length as the first synchronization sequence.

105. Perform mutual quality sampling on the plurality of fourth sequences to obtain a plurality of second sampling sequences.

106. Perform a cross-correlation operation on each of the first sampling sequence and each of the second sampling sequences to obtain a first set of correlation values, where the cross-correlation operation is relative to time between the two sequences. The sliding dot product, the first set of correlation values is used to indicate the correlation of the first sample sequence and each of the second sample sequences.

107: Compare a peak of the first set of correlation values with a first preset threshold.

108. When a peak value in the first group of correlation values is greater than a first preset threshold, a position of the second synchronization sequence corresponding to a peak in the first group correlation value in the synchronization signal is used as a signal with the base station. The starting position of the synchronization.

The synchronization signal is mainly used for frame signal detection, symbol timing synchronization, and coarse carrier frequency offset estimation when the mobile terminal initially enters the network or wakes up from sleep.

The local sync signal (i.e., the sync signal in which the first sync sequence is located) can be generated in the following manner: First, an m-sequence of length 255 {a _i |i = 0, ..., 254} is generated, and the generator polynomial is x ⁸ + x ⁶ +x ⁵ +x ⁴ +1, the initial state of the shift register is {0,0,0,0,0,0,0,0,1}. Next, Binary Phase Shift Keying (BPSK) modulation is performed on the m sequence ('0' is mapped to '1', '1' is mapped to '-1'), and the BPSK sequence is obtained {b _i |i= 0,...,254}. Finally, a differential operation is performed on the BPSK sequence to obtain a local synchronization signal {PSS _i+1 =PSS _i *b _i |i=0,...,254}, where PSS ₀ =exp(j*π/4).

In the embodiment of the present invention, a novel data sampling method, that is, co-prime sampling, is mainly used. This sampling method can sample the data without losing the valid information of the data, and ensure that the co-prime sampled data has a good self-correlation property with the original data. That is, in the case where the original data has good autocorrelation properties, the co-prime sampled data also has good autocorrelation properties. The co-prime sampling uses the M and N prime numbers to uniformly sample the data x(n), that is, the data can be divided by M*N as a sampling period. When using M and N two prime numbers, the sampling rate is lower than the Nyquist sampling rate, and the sampling frequency is

Since the data length after co-prime sampling is related to the sampling factors M and N, in order to facilitate selection of the sampling factor according to the length of the sampled data, the length of the original sequence (for example, the first synchronization sequence) is p, and the sequence after sampling by co-prime (for example, The length of a sample sequence is q, and the sampling factors M and N should satisfy the following conditions:

That is to say, the sampling frequency is the ratio of the length of the sample after sampling to the length of the sequence before sampling.

For example,

For example, let the original data length before sampling be 255, and the desired sampled sequence length is 119, then the sampling frequency is

Since the values of M and N can only be prime numbers, the values of M and N can be as follows: M=3, N=5, or M=5, N=3.

The degree of freedom in the two sample data sampling parameters can be expressed as k = Mn ₁ -Nn _2, when -M + 1≤n ₂ ≤M-1 is satisfied 0≤n _{1 ≤N-1,} and the degree of freedom k Any integer value within {0, MN-1} can be taken.

The co-prime sampling is described in detail below. The data x(n) of length N is co-prime sampled, and the sampling parameters are M and N, respectively, and the sampling period T _c is M*N. The data x (n) in accordance with the sampling period T _c is divided into several segments, if N can be exactly divisible by T _c, then x (n) within each section is divided into several segments uniformly data within each segment, respectively, and sampling parameters M N performs uniform sampling. If N cannot be divisible by T _c , then x(n) will be divided into several pieces of uniform data and a piece of data less than T _c in length, and each segment will be uniformly sampled with sampling parameters M and N respectively.

The following is a detailed description of the co-prime sampling of the local synchronization signal of LTE-M. Assuming x(n) is a 255-point PSS time domain sequence, where the sampling parameter is set to M=3, N=5, then the co-prime sampling period can be expressed as M*N=15. The samples are evenly spaced down in 3 cycles and 5 parameters in one cycle to obtain the sampled sequence:

{PSS _j |j=0,1,...,118}=PSS ₀ , PSS ₃ , PSS ₅ , PSS ₆ , PSS ₉ , PSS ₁₀ , PSS ₁₂ , ... PSS ₂₅₂ .

The remaining sequence is:

{PSS _k |k=0,1,...,135}=PSS ₁ ,PSS ₂ ,PSS ₄ ,PSS ₇ ,PSS ₈ ,PSS ₁₁ ,PSS ₁₃ ,PSS ₁₄ ,...PSS ₂₅₄ .

The first synchronization sequence in step 101 is the sequence carried by the local synchronization signal described above. The local synchronization signal can pre-exist local signals for the mobile terminal. The first synchronization sequence carried by the local synchronization signal may be a Pseudo-noise (PN) sequence, and the pseudo noise sequence has good randomness and correlation characteristics close to white noise.

In an embodiment of the present invention, the mobile terminal may determine a plurality of new sequences (eg, a fourth sequence) according to a second synchronization sequence carried by the synchronization signal sent by the base station. For example, the mobile terminal may perform a difference operation on the second synchronization sequence carried by the synchronization signal sent by the base station to obtain a solution sequence. A plurality of third sequences whose data length is a preset value are intercepted from the solution sequence. A plurality of third sequences are subjected to preset downsampling to obtain a plurality of fourth sequences.

For example, the mobile terminal can receive the sequence sent by the base station and place the last 5120 sample points of the previous frame before the received current frame data to obtain a new sequence {s _i |i=0,1,...}. Performing a difference operation on the new sequence to obtain a sequence after the difference is obtained

Among them, i=21,22,...,

Represents the conjugate of x. Then, with a certain value x as a step, a plurality of sequences whose data length is a preset value are sequentially intercepted from the sequence after the difference difference, where x is a positive integer. For example, a plurality of sequences sequentially intercepted are [1:5100], [x+1:x+5100], [2x+1:2x+5100]. Then, each of the plurality of sequences is downsampled separately. For example, one sample value is taken for every 20 sample values in the sequence [1:5100], and a fourth sequence having the same number of points as the local sequence data is obtained.

The embodiment of the present invention does not limit the sampling multiple. For example, the number 20 in the above embodiment is a system parameter that the system can preset. When the base station sends a signal to the mobile terminal, the signal is upsampled by 20 times. Therefore, after receiving the signal sent by the base station, the mobile terminal performs 20 times downsampling when downsampling multiple sequences, that is, every 20 sample values are taken. 1 sample value. When the mobile terminal receives the signal sent by the base station, when the number of data is represented by 20 sample points, the sampling rate for downsampling the multiple sequences is set to 20, that is, it can be selected from every 20 sample values. One sample value is used as the sampling point of the new fourth sequence.

The length of the data to be intercepted in the embodiment of the present invention is not limited. For example, only 5100 data points are intercepted as an example for exemplary description. That is, taking the local sequence as 255 sample points and the sampling rate as 20 as an example, 5100 data points can be intercepted at the time of interception.

In an embodiment of the present invention, the sampling parameters for performing the mutual sampling on the locally stored first synchronization sequence and the sampling parameters for performing the mutual sampling on the plurality of fourth sequences are the same.

The same sampling parameter of the co-prime sampling means that the two prime numbers M and N at the time of sampling are the same, that is, the samples are evenly spaced with the prime numbers M and N, respectively.

The cross-correlation operation is the sliding point product between the two sequences with respect to time. For example, if two sequences are represented by f(t) and g(t), respectively, the cross-correlation operation can be defined as R(u)=f(t)*g(-t), where R(u) is cross-correlation The result of the operation. The result of the cross-correlation operation indicates the degree of correlation between the two time series, that is, the degree of correlation between the values of the random signal at any two different times when the result of the cross-correlation operation.

For cross-correlation operations, the length of the first sample sequence is the same as the length of the second sample sequence. In one embodiment of the invention, the length of each fourth sequence before sampling is also the same as the length of the first synchronization sequence, so that the sequences are matched in position.

Optionally, as an embodiment of the present invention, the mobile terminal may determine, according to a cross-correlation operation result of the first sampling sequence and the multiple second sampling sequences, a starting position in the second synchronization sequence that is synchronized with the base station. For example, performing a cross-correlation operation on the first sampling sequence and the plurality of second sampling sequences respectively to obtain a first group correlation value; comparing a peak value in the first group correlation value with a first preset threshold value; When the peak value in the group correlation value is greater than the first preset threshold value, the position of the second synchronization sequence corresponding to the peak value is taken as the starting position synchronized with the base station.

Further, when the peak value in the first group of correlation values is less than or equal to the first preset threshold value, Performing a cross-correlation operation on the first remaining sequence and the plurality of second remaining sequences respectively to obtain a second set of correlation values. The first set of correlation values and the second set of correlation values are added to obtain a third set of correlation values (ie, total correlation values). The maximum value selected from the third set of correlation values is determined as the peak value of the third set of correlation values. When the peak value of the third group correlation value is greater than the second preset threshold value, the position of the second synchronization sequence corresponding to the peak value of the third group correlation value is used as a starting position synchronized with the base station. The first remaining sequence is a sequence remaining after the first synchronization sequence stored locally, and the second remaining sequence is a sequence remaining after the fourth sequence is subjected to mutual sampling, and the second group of correlation values is used to represent The correlation between the first remaining sequence and each of the second remaining sequences, and the third set of correlation values are used to indicate the relevance of the first synchronization sequence and each of the fourth sequences, respectively.

Specifically, the mobile terminal may perform a cross-correlation operation on the plurality of received sampling sequences (ie, the second sampling sequence) respectively using the local sampling sequence (ie, the first sampling sequence). When the peak value of the correlation value obtained by the cross-correlation operation is greater than the first preset threshold value, the position corresponding to the peak value may be recorded as the frame start position. When the peak value of the correlation value obtained by the cross-correlation operation is less than or equal to the first preset threshold, the local residual sequence (ie, the first remaining sequence) is used to cross-correlate the plurality of received residual sequences (ie, the second remaining sequence) respectively. Operation. The correlation values obtained by the two cross-correlation operations are added to obtain a third group correlation value, and the maximum value is selected from the third group correlation value as the total correlation peak. The total correlation peak is compared to a second predetermined threshold. When the total correlation peak is greater than the second preset threshold, the position corresponding to the total correlation peak may be recorded as the frame start position. When the total correlation peak is less than or equal to the second preset threshold, the mobile terminal may continue to receive the next frame data sent by the base station, and perform synchronous detection on the next frame data.

It should be understood that the specific operation steps when the calculated peak value in the embodiment of the present invention is a critical point (for example, the first preset threshold value and the second preset threshold value) may be determined as a starting position synchronized with the base station. It can also be judged as not the starting position of synchronization. For example, in the embodiment of the present invention, when the peak value in the first group of correlation values is greater than or equal to the first preset threshold, the location of the second synchronization sequence corresponding to the peak may be synchronized with the base station. The starting position. And when the peak value in the first group of correlation values is less than the first preset threshold value, the first remaining sequence and the plurality of second remaining sequences are respectively subjected to cross-correlation operation.

The first preset threshold value and the second preset threshold value in the embodiment of the present invention are empirical values obtained according to experience. For example, the starting position of the synchronization can be found by simulation, and the first preset threshold value and the second preset threshold value are set according to the correlation value corresponding to the starting position of the synchronization.

The mobile terminal can find the sequence stored locally with the mobile terminal in the sequence sent by the base station. Sequences of the same or similarity, such as to achieve synchronization with the base station. The greater the correlation value of the two sequences, the greater the similarity between the two sequences. Therefore, in the embodiment of the present invention, the maximum value among the correlation values is found. However, when the maximum value of the correlation values still does not reach the preset threshold, it is considered that synchronization cannot be achieved. The terminal can be considered to be synchronized with the base station only when the maximum value of the correlation values is greater than the preset threshold.

In the embodiment of the present invention, the locally stored sequence and the sequence sent by the base station are mutually sampled, so that the amount of data of the cross-correlation operation is reduced, the computational complexity is reduced, and the synchronization time is shortened. Moreover, the self-correlation characteristics of the sequence after the mutual sampling are good, so that the computational complexity can be reduced, and the good autocorrelation property of the sequence is retained, which is beneficial to the synchronization between the mobile terminal and the base station.

In the embodiment of the present invention, by performing mutual quality sampling on the sequence, since the number of sampling points is reduced, the accuracy of determining the synchronization starting position is also correspondingly reduced. Therefore, reducing the computational complexity comes at the expense of the accuracy of a certain synchronization start position. However, the simulation results show that with the improvement of the signal-to-noise ratio, the synchronous detection probability of the mutual sampling of the sequence has a relatively high reliability, that is, with the improvement of the signal-to-noise ratio, the probability of synchronous detection of the mutual sampling (ie The probability of mutual quality detection is getting closer to the synchronous detection probability (ie, the existing detection probability) of performing cross-correlation operations on all data points. The detection probability here is the probability that it can be synchronized. For example, when the frequency offset is 500 Hz and the signal to noise ratio is -10 db, the existing detection probability is 0.48, and the probability of mutual quality detection is 0.24. When the frequency offset is 500 Hz and the signal-to-noise ratio is -7 db, the existing detection probability is 0.92, and the probability of mutual quality detection is 0.94. When the frequency offset is 500 Hz and the signal-to-noise ratio is -3 db, the existing detection probability is 0.97, and the probability of mutual quality detection is 0.96. When the frequency offset is 500 Hz and the signal-to-noise ratio is 0 db, the existing detection probability is 0.98, and the probability of mutual quality detection is 0.97.

Under the same frequency offset, as the signal-to-noise ratio increases, the synchronization offset obtained by the mutual sampling method becomes larger and larger, and the synchronization error becomes smaller and smaller.

Under the same frequency offset, the computational complexity of the synchronization method of the mutual sampling is lower than that of the cross-correlation operation of all the data points. And as the signal-to-noise ratio increases, the gap in computational complexity increases. When the signal-to-noise ratio is greater than -7 db and less than 0 db, the computational complexity of the synchronization method of the mutual sampling is much less than half of the computational complexity of performing cross-correlation operations on all data points.

In the embodiment of the present invention, the self-sampling of the sequence has better autocorrelation characteristics than the sequence obtained by using other sampling methods, and is more convenient for achieving synchronization quickly. For example, the synchronization method of the embodiment of the present invention adopts a co-prime sampling mechanism for the local PN sequence, and can have good data in the original data. On the basis of the autocorrelation property, the sampled data still has good autocorrelation properties, which can ensure the synchronization detection performance, that is, the computational complexity is reduced, and the probability of synchronization is not affected.

Embodiments of the present invention are described in more detail below with reference to specific examples. It should be noted that these examples are only intended to assist those skilled in the art to better understand the embodiments of the present invention and not to limit the scope of the embodiments of the present invention.

FIG. 2 is a schematic flowchart of a synchronization method according to another embodiment of the present invention. In the embodiment of the present invention, only the 255 sampling points are included in the synchronization sequence of the local synchronization signal stored by the mobile terminal, and the system preset preset multiple is 20 as an example.

201. Receive a synchronization signal sent by a base station.

A synchronization signal transmitted by the base station is received, and the synchronization signal carries a reception synchronization sequence (eg, a second synchronization sequence). Assume that the sample rate of the sync signal is 240Ksps.

202: Save the last 5120 sample points of the previous frame before the received frame data, and save the last 5120 sample points of the frame.

Adding the last 5120 sample points of the previous frame before the data of the synchronization sequence, the sequence {s _i |i=0,1,...} is obtained.

203. Differential demodulation of adjacent symbols.

The mobile terminal can perform a difference operation on the sequence {s _i |i=0,1,...} to obtain a sequence after the difference is obtained.

Among them, i=21,22,...,

Represents the conjugate of x.

204. Acquire a plurality of truncated sequences from the sequence after the difference is solved.

Taking a preset value x as a step, a plurality of sequences with a data point number of 5100 are intercepted from the sequence after the difference is solved, and a plurality of sequences are down-sampled, and one sample value is taken for every 20 sample values to obtain a plurality of data. A truncated sequence of points 255.

Generally, the step size x=1 is taken. For example, a plurality of sequences with data points of 5100 are sequentially intercepted from the sequence after the difference is solved: [1:5100], [2:5101], [3:5102].

The above plurality of sequences are downsampled, for example, one sample value is taken every 20 sample values. For example, the truncated sequence obtained after downsampling the sequence [1:5100] is represented as {c _q |q=0, 1, . . . , 254}. Specifically, it may be c _q =1, 21, 41, 61, ..., and may also be c _q = 2, 22, 42, 62, ... and the like. The present invention does not limit the first data point of the 20 sample values for downsampling.

205. Perform local sampling on the local PN sequence to obtain a local sampling sequence.

The synchronization signal can be stored locally in advance, and the synchronization signal carries a local synchronization sequence (for example, the first synchronization sequence) {b _i |i=0,...,254}. The local synchronization sequence can be a PN sequence. The mobile terminal may perform mutual quality sampling on the local synchronization sequence to obtain a local sample sequence (eg, a first sample sequence) and a local residual sequence (eg, a first remaining sequence).

For example, the local sequence {b _i |i=0,...,254} is subjected to mutual sampling, and the sampling parameters are set to M=3, N=5. The local sampling sequence obtained after the mutual sampling is {b _j |j=0,1,...,118}, specifically, b _j =b ₀ , b ₃ , b ₅ , b ₆ , b ₉ , b ₁₀ , b ₁₂ ,...b ₂₅₂ . The local residual sequence is {b _k |k=0,1,...,135}, specifically, b _k =b ₁ , b ₂ , b ₄ , b ₇ , b ₈ , b ₁₁ , b ₁₃ , b ₁₄ ,... b ₂₅₄ .

206. Perform multi-sample sampling on multiple truncated sequences to obtain a received sampling sequence.

The mobile terminal may perform multi-sample sampling of the plurality of truncated sequences obtained in step 204 to obtain a received sample sequence (eg, a second sample sequence) and a received residual sequence (eg, a second remaining sequence). Here, only the truncation sequence obtained by downsampling the sequence [1:5100] is {c _q |q=0,1,...,254} as an example.

For example, the truncated sequence {c _q |q=0, 1, ..., 254} is subjected to mutual sampling, and the sampling parameters are set to M=3, N=5. The received sample sequence obtained after the mutual sampling is {r _j |j=0,1,...,118}, specifically, r _j =r′ ₀ , r′ ₃ , r′ ₅ , r′ ₆ , r′ ₉ , r' ₁₀ , r' ₁₂ , ... r' ₂₅₂ . The remaining sequence is received as {r _k |k=0,1,...,135}, specifically, r _k =r′ ₁ ,r′ ₂ ,r′ ₄ ,r′ ₇ ,r′ ₈ ,r′ ₁₁ ,r ' ₁₃ , r' ₁₄ ,...r' ₂₅₄ .

Step 204 obtains a plurality of truncated sequences, and after performing multi-slice sampling on the plurality of truncated sequences, a plurality of received sampling sequences and a plurality of received residual sequences are obtained.

207. Perform cross-correlation operations on the local sampling sequence and the multiple received sampling sequences respectively.

The mobile terminal may perform a cross-correlation operation on the local sampling sequence obtained in step 205 and the multiple received sampling sequences obtained in step 206 to obtain correlation values of a set of cross-correlation operations.

Where h ₁ is the index of the correlation window or the starting position of the second synchronization sequence.

208. Acquire a first peak of the correlation values of the cross correlation operation.

The maximum value is selected from the correlation values of a set of cross-correlation operations obtained in step 207 as the first correlation peak, that is, the correlation peak in the data frame.

209. Determine whether the first peak is greater than a first preset threshold.

The first preset threshold is a preset threshold of the mobile terminal. The mobile terminal may compare the first peak obtained in step 208 with the size of the first preset threshold.

210. The position corresponding to the first peak is the starting position of the synchronization.

When it is determined in step 209 that the first peak is greater than the first preset threshold, the location of the second synchronization sequence corresponding to the peak is used as a starting position synchronized with the base station.

211. Perform cross-correlation operations on the local residual sequence and the multiple received residual sequences respectively.

When it is determined in step 209 that the first correlation peak is less than or equal to the first preset threshold, the local residual sequence and the multiple received residual sequences are respectively subjected to cross-correlation operation to obtain correlation values of another set of cross-correlation operations.

Where h ₂ is the index of the correlation window or the starting position of the second synchronization sequence.

212. The total correlation value is determined by two sets of correlation values.

The total correlation value can be determined from the above two sets of correlation values. For example, the correlation value of a set of cross-correlation operations obtained in step 207 and the correlation value of another set of cross-correlation operations obtained in step 211 are added to obtain a total correlation value:

213. The maximum value is selected from the total correlation values as the total peak value.

A maximum value is selected from the total correlation values obtained in step 212, and the maximum value is determined as a total peak value (e.g., a second peak value).

214. Determine whether the total peak value is greater than a second preset value.

The second preset threshold is a preset threshold of the mobile terminal. The mobile terminal can compare the second peak obtained in step 213 with the size of the second preset threshold.

215. The position corresponding to the second peak is the starting position of the synchronization.

When it is determined in step 214 that the second peak is greater than the second preset threshold, the location of the second synchronization sequence corresponding to the second peak is used as a starting position synchronized with the base station.

216. Receive the next frame of data.

When it is determined in step 214 that the second peak is less than or equal to the second preset threshold, the next frame data signal is received, and the flow returns to step 201. The mobile terminal can perform synchronous detection on the next frame of data signals until the starting position of the synchronization is found.

The synchronization method according to an embodiment of the present invention has been described in detail above with reference to FIGS. 1 through 2, and a synchronization apparatus according to an embodiment of the present invention will be described below with reference to FIGS. 3 and 4.

Figure 3 is a block diagram of a synchronization device in accordance with one embodiment of the present invention. The apparatus of Figure 3 can perform the methods of Figures 1 and 2. The synchronization device 10 of FIG. 3 may be a mobile terminal, including a first prime sampling unit 11, a de-sigma unit 12, an intercepting unit 13, a downsampling unit 14, a second inter-priming unit 15, and a first cross-correlation unit 16, Comparison unit 17, first synchronization unit 18.

The first quality sampling unit 11 is configured to perform mutual sampling on the first synchronization sequence to obtain a first sampling sequence, where the first synchronization sequence is stored in the mobile terminal, and the mutual quality sampling is performed by using two prime numbers respectively. The sequence is sampled evenly at intervals.

The solution difference unit 12 is configured to perform a difference operation on the second synchronization sequence carried by the synchronization signal sent by the base station to obtain a solution sequence.

The intercepting unit 13 is configured to intercept a plurality of third sequences whose data length is a preset value from the solution difference sequence obtained in the solution difference unit.

The downsampling unit 14 is configured to downsample a plurality of third sequences obtained by the intercepting unit to obtain a plurality of fourth sequences, wherein each fourth sequence has the same length as the first synchronization sequence.

The second quality sampling unit 15 is configured to perform mutual quality sampling on the plurality of fourth sequences obtained by the down sampling unit to obtain a plurality of second sampling sequences.

The first cross-correlation operation unit 16 is configured to perform a cross-correlation operation on each of the first sampling sequence obtained by the first sampling unit and each of the second sampling sequences obtained by the second inter-priming sampling unit. The first set of related values. Wherein, the cross-correlation operation is a sliding point product with respect to time between two sequences, and the first group of correlation values is used to indicate the correlation between the first sampling sequence and each of the second sampling sequences.

The comparing unit 17 is configured to compare the peak value of the first group correlation value obtained by the first cross-correlation operation unit with the first preset threshold value.

The first synchronization unit 18 is configured to synchronize the second synchronization sequence corresponding to the peak in the first group correlation value when the peak value in the first group correlation value obtained by the cross-correlation operation unit is greater than the first preset threshold value The position in the signal serves as the starting position for synchronizing the signals with the base station.

Optionally, as an embodiment, the length p of the first synchronization sequence, the length q of the first sampling sequence, and the two prime numbers M and N of the mutual sampling should satisfy:

Optionally, as an embodiment, the apparatus further includes a second cross-correlation operation unit, a superposition unit, a determination unit, and a second synchronization unit. The second cross-correlation operation unit is configured to divide the first remaining sequence and the plurality of second remaining sequences when the peak value in the first group of correlation values is less than or equal to the first preset threshold value Do not perform cross-correlation operations to obtain a second set of correlation values. The first remaining sequence is a sequence remaining after performing the mutual sampling on the locally stored first synchronization sequence. The second remaining sequence is the sequence remaining after the fourth sequence is subjected to mutual sampling. The second set of correlation values is used to indicate the correlation of the first remaining sequence and each of the second remaining sequences, respectively. The superposition unit is configured to add the first set of correlation values and the second set of correlation values to obtain a third set of correlation values, and the third set of correlation values is used to indicate the correlation between the first synchronization sequence and each of the fourth sequences. The determining unit is configured to determine, from the third set of correlation values, a maximum value as a peak value of the third group of correlation values. The second synchronization unit is configured to: when the peak of the third group correlation value is greater than the second preset threshold, the position of the second synchronization sequence corresponding to the peak of the third group correlation value as a starting position synchronized with the base station.

A synchronization device according to an embodiment of the present invention may correspond to specific steps in the synchronization method of the embodiment of the present invention, and each unit/module in the device and the other operations and/or functions described above are respectively implemented in FIGS. 1 and 2 The corresponding flow of the method shown is not repeated here for the sake of brevity.

4 is a schematic block diagram of a mobile terminal in accordance with an embodiment of the present invention. The mobile terminal 20 of FIG. 4 includes a processor 21, a memory 22, and a receiver 24. The processor 21 can control the receiver 24 to receive signals and can be used to process signals. Memory 22 can include read only memory and random access memory and provides instructions and data to processor 21. The various components of mobile terminal 20 are coupled together by a bus system 23, which in addition to the data bus includes a power bus, a control bus, and a status signal bus. However, for clarity of description, various buses are labeled as the bus system 23 in the figure.

The method disclosed in the foregoing embodiment of the present invention may be applied to the processor 21 or implemented by the processor 21. In the implementation process, each step of the above method may be completed by an integrated logic circuit of hardware in the processor 21 or an instruction in the form of software. The processor 21 can be a general purpose processor, a digital signal processor, an application specific integrated circuit, a field programmable gate array or other programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, and can be implemented or executed in an embodiment of the invention. Various methods, steps, and logic blocks of the disclosure. A general purpose processor can be a microprocessor or any conventional processor or the like. The steps of the method disclosed in the embodiments of the present invention may be directly implemented as a hardware processor, or may be performed by a combination of hardware and software modules in the processor. The software module can be located in a conventional storage medium such as random access memory, flash memory, read only memory, programmable read only memory or electrically erasable programmable memory, registers, and the like. The storage medium is located in the memory 22, and the processor 21 reads the information in the memory 22 and combines the hardware to perform the steps of the above method.

Specifically, the receiver 24 can receive the second synchronization sequence carried by the synchronization signal sent by the base station. The processor 21 may perform mutual quality sampling on the first synchronization sequence to obtain a first sampling sequence. The first synchronization sequence is stored in the mobile terminal, and the mutual quality sampling is to sequentially sample the sequence using two prime numbers at intervals. The second synchronization sequence is subjected to a difference operation to obtain a solution sequence. A plurality of third sequences of a predetermined length are intercepted from the solution sequence. Downsampling the plurality of third sequences results in a plurality of fourth sequences, each of the lengths of the fourth sequence being the same as the length of the first synchronization sequence. The plurality of fourth sequences are separately subjected to mutual sampling to obtain a plurality of second sampling sequences. Performing a cross-correlation operation on each of the first sampling sequence and each of the second sampling sequences to obtain a first set of correlation values, wherein the cross-correlation operation is a sliding point between the two sequences with respect to time Product, the first set of correlation values is used to indicate the correlation of the first sample sequence and each of the second sample sequences. The peak in the first set of correlation values is compared to a first predetermined threshold. When the peak value in the first group of correlation values is greater than the first preset threshold value, the position of the second synchronization sequence corresponding to the peak value in the first group correlation value in the synchronization signal is used as the start of signal synchronization with the base station position.

Optionally, as an embodiment, the processor 21 may perform cross-correlation between the first remaining sequence and the multiple second remaining sequences respectively when the peak value of the first group of correlation values is less than or equal to the first preset threshold. Operate to get the second set of correlation values. The first set of correlation values and the second set of correlation values are added to obtain a third set of correlation values. The maximum value selected from the third set of correlation values is determined as the peak value of the third set of correlation values. When the peak value of the third group correlation value is greater than the second preset threshold value, the position of the second synchronization sequence corresponding to the peak value of the third group correlation value is used as a starting position synchronized with the base station. The first remaining sequence is a sequence remaining after the first synchronization sequence stored locally, and the second remaining sequence is a sequence remaining after the fourth sequence is subjected to mutual sampling, and the second group of correlation values is used to represent Correlation between the first remaining sequence and each of the second remaining sequences, and the third set of correlation values is used to represent the first The correlation between the step sequence and each of the fourth sequences.

Those skilled in the art will appreciate that the various method steps and elements described in connection with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both, in order to clearly illustrate hardware and software. Interchangeability, the steps and composition of the various embodiments have been generally described in terms of function in the foregoing description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the solution. Different methods may be used to implement the described functionality for each particular application, but such implementation should not be considered to be beyond the scope of the present invention.

The methods or steps described in connection with the embodiments disclosed herein may be implemented in hardware, a software program executed by a processor, or a combination of both. Software programs can be placed in random access memory (RAM), memory, read only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or technical fields. Any other form of storage medium known.

Although the present invention has been described in detail by reference to the accompanying drawings in the preferred embodiments, the invention is not limited thereto. Various equivalent modifications and alterations to the embodiments of the present invention may be made by those skilled in the art without departing from the spirit and scope of the invention.

Claims

A method for synchronizing signals, comprising:

The first synchronization sequence is subjected to mutual sampling to obtain a first sampling sequence, wherein the first synchronization sequence is stored in a mobile terminal, and the mutual quality sampling is to sequentially sample the sequence using two prime numbers respectively;

Performing a difference operation on the second synchronization sequence carried by the synchronization signal sent by the base station to obtain a solution sequence;

Extracting, from the solution difference sequence, a plurality of third sequences having a preset length;

Downsampling the plurality of third sequences respectively to obtain a plurality of fourth sequences, wherein a length of each fourth sequence is the same as a length of the first synchronization sequence;

Performing the mutual sampling on the plurality of fourth sequences to obtain a plurality of second sampling sequences;

Performing a cross-correlation operation on each of the first sampling sequence and each of the plurality of second sampling sequences to obtain a first set of correlation values, wherein the cross-correlation operation is between two sequences The first set of correlation values is used to indicate a correlation between the first sample sequence and each of the second sample sequences, respectively, relative to a slip product of time;

Comparing a peak value of the first set of correlation values with a first preset threshold value;

And when the peak of the first set of correlation values is greater than the first preset threshold, the second synchronization sequence corresponding to the peak of the first set of correlation values is in the synchronization signal The location serves as a starting location for synchronizing signals with the base station.
The method of claim 1 wherein said length p of said first synchronization sequence, length q of said first sequence of samples, and two prime numbers M and N of said mutual sample are satisfied:
The method of claim 1 or 2, wherein the method further comprises:

When the peak value of the first group of correlation values is less than or equal to the first preset threshold value, performing a cross-correlation operation on the first remaining sequence and the plurality of second remaining sequences respectively to obtain a second group correlation value, The first remaining sequence is a sequence remaining after performing the mutual sampling on the locally stored first synchronization sequence, and the second remaining sequence is a sequence remaining after the mutual sampling of the fourth sequence. The second set of correlation values is used to indicate a correlation between the first remaining sequence and each of the second remaining sequences;

Adding the first set of correlation values and the second set of correlation values to obtain a third set of correlation values, the third set of correlation values being used to represent the first synchronization sequence and each of the fourth The relevance of the sequence;

Selecting a maximum value from the third set of correlation values as a peak value of the third set of correlation values;

When the peak value of the third group correlation value is greater than the second preset threshold value, the location of the second synchronization sequence corresponding to the peak of the third group correlation value is used as a starting position synchronized with the base station.
A device for synchronizing signals, comprising:

a first quality sampling unit, configured to perform mutual quality sampling on the first synchronization sequence to obtain a first sampling sequence, where the first synchronization sequence is stored in a mobile terminal, and the mutual quality sampling is separated by using two prime numbers Sequentially sample the sequence;

a difference unit, configured to perform a difference operation on the second synchronization sequence carried by the synchronization signal sent by the base station, to obtain a solution sequence;

An intercepting unit, configured to intercept, from the solution difference sequence obtained in the solution difference unit, a plurality of third sequences having a preset length;

a downsampling unit, configured to downsample the plurality of third sequences obtained by the intercepting unit to obtain a plurality of fourth sequences, wherein a length of each fourth sequence is longer than a length of the first synchronization sequence the same;

a second quality sampling unit, configured to perform the mutual quality sampling on the plurality of fourth sequences obtained by the down sampling unit, to obtain a plurality of second sampling sequences;

a first cross-correlation operation unit, configured to: use the first sampling sequence obtained by the first sampling unit and each second sampling of the plurality of second sampling sequences obtained by the second prime sampling unit The sequence performs a cross-correlation operation to obtain a first set of correlation values, wherein the cross-correlation operation is a sliding point product with respect to time between two sequences, and the first group of correlation values is used to represent the first sample a correlation between the sequence and each of the second sample sequences;

a comparing unit, configured to compare a peak value of the first group correlation value obtained by the first cross-correlation operation unit with a first preset threshold value;

a first synchronization unit, configured to: when a peak value of the first group of correlation values obtained by the cross-correlation operation unit is greater than the first preset threshold, a peak value in a correlation value with the first group Corresponding position of the second synchronization sequence in the synchronization signal is used as a starting position for synchronizing signals with the base station.
The apparatus according to claim 4, wherein said first synchronization sequence has a length p, The length q of the first sampling sequence and the two prime numbers M and N of the mutual sampling should satisfy:
The device of claim 4 or 5, wherein the device further comprises:

a second cross-correlation operation unit, configured to perform cross-correlation between the first remaining sequence and the plurality of second remaining sequences respectively when a peak value of the first group of correlation values is less than or equal to the first preset threshold value Computing, to obtain a second set of correlation values, wherein the first remaining sequence is a sequence remaining after the first synchronization sequence of the locally stored first synchronization sequence, and the second remaining sequence is the fourth sequence Performing a sequence remaining after the prime sampling, the second set of correlation values being used to indicate the correlation between the first remaining sequence and each of the second remaining sequences;

a superimposing unit, configured to add the first set of correlation values and the second set of correlation values to obtain a third set of correlation values, where the third set of correlation values is used to represent the first synchronization sequence respectively and each Correlation of the fourth sequence;

a determining unit, configured to select a maximum value from the third group of correlation values as a peak value of the third group correlation value;

a second synchronization unit, configured to: when a peak of the third group correlation value is greater than a second preset threshold, a location of a second synchronization sequence corresponding to a peak of the third group correlation value as the base station The starting position to achieve synchronization.
A mobile terminal, comprising: a memory, a receiver, and a processor;

a memory for storing the first synchronization sequence;

a processor, configured to perform mutual quality sampling on the first synchronization sequence, to obtain a first sampling sequence, where the mutual quality sampling is to uniformly sample the sequence using two prime numbers;

a receiver, configured to receive a second synchronization sequence carried by the synchronization signal sent by the base station;

The processor is further configured to perform a difference operation on the second synchronization sequence to obtain a solution sequence, and intercept a plurality of third sequences of a preset value from the solution sequence;

The processor is further configured to perform down sampling on the plurality of third sequences to obtain a plurality of fourth sequences, and perform the mutual quality sampling on the plurality of fourth sequences to obtain a plurality of second sampling sequences. The length of each of the fourth sequences is the same as the length of the first synchronization sequence;

The processor is further configured to perform a cross-correlation operation on each of the first sampling sequence and each of the plurality of second sampling sequences to obtain a first set of correlation values, and the first The peak value in the group correlation value is compared with the first preset threshold value, and the peak value in the first group correlation value When the value is greater than the first preset threshold, the position of the second synchronization sequence corresponding to the peak of the first group of correlation values in the synchronization signal is used as a signal synchronization with the base station. a start position, wherein the cross-correlation operation is a sliding dot product with respect to time between two sequences, the first set of correlation values being used to represent the first sample sequence and each of the second sample sequences Relevance.
The mobile terminal according to claim 7, wherein the length p of the first synchronization sequence, the length q of the first sampling sequence, and the two prime numbers M and N of the mutual sampling are satisfied:
The mobile terminal according to claim 7 or 8, wherein the processor is further configured to: when a peak value of the first group of correlation values is less than or equal to the first preset threshold value, Performing a cross-correlation operation on the first remaining sequence and the plurality of second remaining sequences respectively to obtain a second set of correlation values, adding the first set of correlation values and the second set of correlation values to obtain a third set of correlation values, from Determining a maximum value of the third group of correlation values as a peak value of the third group correlation value, and when the peak value of the third group correlation value is greater than a second preset threshold value, The position of the second synchronization sequence corresponding to the peak is used as a starting position for synchronizing with the base station, wherein the first remaining sequence is a sequence remaining after performing mutual quality sampling on the locally stored first synchronization sequence. The second remaining sequence is a sequence remaining after the mutual sampling of the fourth sequence, and the second set of correlation values is used to indicate the correlation between the first remaining sequence and each of the second remaining sequences, The third set of correlation values is used to represent the Each of the first synchronization sequence and said fourth sequence respectively relevance.