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WO2017036325A1 - 信号同步的方法和信号同步的装置 - Google Patents

信号同步的方法和信号同步的装置 Download PDF

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Publication number
WO2017036325A1
WO2017036325A1 PCT/CN2016/096392 CN2016096392W WO2017036325A1 WO 2017036325 A1 WO2017036325 A1 WO 2017036325A1 CN 2016096392 W CN2016096392 W CN 2016096392W WO 2017036325 A1 WO2017036325 A1 WO 2017036325A1
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Prior art keywords
sequence
correlation
sampling
synchronization
sequences
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English (en)
French (fr)
Inventor
王铠尧
刘永俊
钟怡
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Huawei Technologies Co Ltd
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Huawei Technologies Co Ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L7/00—Arrangements for synchronising receiver with transmitter

Definitions

  • the present invention relates to the field of communications and, more particularly, to a method of signal synchronization and a device for signal synchronization.
  • 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.
  • 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.
  • the location of symbol timing synchronization can also be obtained based on the autocorrelation property of the synchronization sequence.
  • 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.
  • the mobile terminal may re-search for the synchronization information to access the cell again.
  • 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.
  • Embodiments of the present invention provide a method for signal synchronization and a device for synchronizing signals, which can reduce computational complexity.
  • a method for signal synchronization 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.
  • 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:
  • 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
  • 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 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 :
  • 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
  • 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.
  • 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.
  • 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 :
  • 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
  • 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.
  • 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.
  • FIG. 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.
  • FIG. 3 is a block diagram of a synchronization device in accordance with one embodiment of the present invention.
  • FIG. 4 is a block diagram of a synchronization device according to another embodiment of the present invention.
  • a mobile terminal in the embodiment of the present invention may be referred to as a user equipment.
  • UE User Equipment
  • Terminal Terminal
  • MS mobile station
  • 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.
  • FIG. 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.
  • each fourth sequence has the same length as the first synchronization sequence.
  • 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.
  • 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 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.
  • 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.
  • 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 ⁇ .
  • BPSK Binary Phase Shift Keying
  • a novel data sampling method that is, co-prime sampling
  • 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
  • the length of the original sequence (for example, the first synchronization sequence) is p
  • the sequence after sampling by co-prime (for example, The length of a sample sequence is q
  • the sampling factors M and N should satisfy the following conditions:
  • the sampling frequency is the ratio of the length of the sample after sampling to the length of the sequence before sampling.
  • 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 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.
  • PN Pseudo-noise
  • 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.
  • a plurality of new sequences eg, a fourth sequence
  • 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,... ⁇ .
  • 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.
  • 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.
  • the number 20 in the above embodiment is a system parameter that the system can preset.
  • 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.
  • 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.
  • 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 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.
  • the length of the first sample sequence is the same as the length of the second sample sequence.
  • 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.
  • 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.
  • the peak value in the first group of correlation values is less than or equal to the first preset threshold value
  • 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.
  • 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
  • the second remaining sequence is a sequence remaining after the fourth sequence is subjected to mutual sampling
  • the second group of correlation values is used to represent The correlation between the first remaining sequence and each of the second remaining sequences
  • the third set of correlation values are used to indicate the relevance of the first synchronization sequence and each of the fourth sequences, respectively.
  • 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).
  • 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.
  • the local residual sequence ie, the first remaining sequence
  • the local residual 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.
  • the specific operation steps when the calculated peak value in the embodiment of the present invention is a critical point may be determined as a starting position synchronized with the base station. It can also be judged as not the starting position of synchronization.
  • the peak value in the first group of correlation values 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.
  • 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.
  • 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.
  • 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.
  • the existing detection probability is 0.48, and the probability of mutual quality detection is 0.24.
  • the existing detection probability is 0.92, and the probability of mutual quality detection is 0.94.
  • the existing detection probability is 0.97, and the probability of mutual quality detection is 0.96.
  • the existing detection probability is 0.98, and the probability of mutual quality detection is 0.97.
  • the synchronization offset obtained by the mutual sampling method becomes larger and larger, and the synchronization error becomes smaller and smaller.
  • 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.
  • 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.
  • 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.
  • 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.
  • FIG. 2 is a schematic flowchart of a synchronization method according to another embodiment of the present invention.
  • the system preset preset multiple is 20 as an example.
  • a synchronization signal transmitted by the base station is received, and the synchronization signal carries a reception synchronization sequence (eg, a second synchronization sequence).
  • a reception synchronization sequence eg, a second synchronization sequence.
  • the sample rate of the sync signal is 240Ksps.
  • 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.
  • i 21,22,..., Represents the conjugate of x.
  • a preset value x 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.
  • the above plurality of sequences are downsampled, for example, one sample value is taken every 20 sample values.
  • the truncated sequence obtained after downsampling the sequence [1:5100] is represented as ⁇ c q
  • the present invention does not limit the first data point of the 20 sample values for downsampling.
  • 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).
  • the local sampling sequence obtained after the mutual sampling is ⁇ b j
  • the local residual sequence is ⁇ b k
  • 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).
  • a received sample sequence eg, a second sample sequence
  • a received residual sequence eg, a second remaining sequence.
  • the received sample sequence obtained after the mutual sampling is ⁇ r j
  • 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.
  • 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.
  • h 1 is the index of the correlation window or the starting position of the second synchronization sequence.
  • 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.
  • 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.
  • the position corresponding to the first peak is the starting position of the synchronization.
  • step 209 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.
  • step 209 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.
  • h 2 is the index of the correlation window or the starting position of the second synchronization sequence.
  • 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:
  • 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).
  • 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.
  • the position corresponding to the second peak is the starting position of the synchronization.
  • step 214 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.
  • step 214 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.
  • FIG. 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 are 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.
  • 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.
  • 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.
  • 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:
  • 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 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • the peak in the first set of correlation values is compared to a first predetermined threshold.
  • 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.
  • 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.
  • 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.
  • 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:
  • 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
  • the second remaining sequence is a sequence remaining after the fourth sequence is subjected to mutual sampling
  • the second group of correlation values is used to represent Correlation between the first remaining sequence and each of the second remaining sequences
  • the third set of correlation values is used to represent the first The correlation between the step sequence and each of the fourth sequences.
  • RAM random access memory
  • ROM read only memory
  • EEPROM electrically programmable ROM
  • EEPly erasable programmable ROM registers
  • hard disk removable disk
  • CD-ROM computer-readable media

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Abstract

本发明实施例提供了一种信号同步方法的和信号同步的装置。该方法包括对本地存储的第一同步序列进行互质采样得到第一采样序列，并根据基站发送的同步信号携带的第二同步序列确定多个短序列，然后对多个短序列分别进行互质采样得到多个第二采样序列，并当第一采样序列和多个第二采样序列的互相关运算得到的第一组相关值中的峰值大于第一预设门限值时，将与第一组相关值中的峰值对应的第二同步序列的位置作为与基站实现同步的起始位置。本发明实施例通过对本地同步序列和接收同步序列都进行互质采样后的序列进行互相关运算以确定与基站实现同步的起始位置，这样能够降低运算复杂度。

Description

信号同步的方法和信号同步的装置
本申请要求于2015年9月2日提交中国专利局、申请号为201510555847.0、发明名称为“信号同步的方法和信号同步的装置”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本发明涉及通信领域，并且更具体地，涉及信号同步的方法和信号同步的装置。
背景技术
移动终端要接入基站与基站进行通信，需要与基站实现同步。符号定时同步是移动终端进行小区搜索以实现同步过程的第一步。在一般的通信系统中，可以通过位同步序列或者帧同步序列良好的自相关特性获取位同步或者帧同步的具体位置。同理，在长期演进技术(Long Term Evolution，LTE)系统中，符号定时同步的位置也可以基于同步序列的自相关特性来获取。
在长期演进-机器对机器(Long Term Evolution-Machine-To-Machine，LTE-M)系统中，高效精确的定时同步算法是确保移动终端快速接入小区的关键。现有LTE-M系统中，移动终端可以采用下列方法实现定时同步：移动终端接收基站发送的同步序列，并对同步序列进行解差分运算，得到解差分后的序列；接着，移动终端使用本地存储的序列对解差分后的序列做滑动相关并从得到的相关值中获取相关峰值；然后，通过判断相关峰值与预先设定的帧检测门限值的大小来确定符号定时同步的位置。当相关峰值大于帧检测门限值时，可以将相关峰值对应的位置作为同步信号的起始位置，完成符号定是同步。当相关峰值小于或者等于帧检测门限值时，移动终端可以重新搜索同步信息以再次接入小区。
但是，由于接收同步序列的数据点数的多少是由带宽决定的，带宽越大，数据点数越大。而且，系统中同步算法的采样率(例如，240Ksps)可以为若干倍(例如，20倍)的符号速率。所以，定时采样点滑动范围非常大。这样，移动终端对所有接收到的数据点都要进行检测，运算量大，运算复杂度高。
发明内容
本发明实施例提供一种信号同步的方法和信号同步的装置，能够降低运算复杂度。
第一方面，提供了一种信号同步的方法，包括：对第一同步序列进行互质采样，得到第一采样序列，其中，所述第一同步序列存储在移动终端，所述互质采样为使用两个质数分别间隔均匀地对序列进行采样；对基站发送的同步信号携带的第二同步序列进行解差分运算，得到解差分序列；从所述解差分序列中截取长度为预设值的多个第三序列；对所述多个第三序列进行下采样，得到多个第四序列，其中，每个第四序列的长度与所述第一同步序列的长度相同；对所述多个第四序列分别进行所述互质采样，得到多个第二采样序列；对所述第一采样序列和所述多个第二采样序列中的每个第二采样序列分别进行互相关运算，得到第一组相关值，其中，所述互相关运算为两个序列之间相对于时间的滑动点积，所述第一组相关值用来表示所述第一采样序列分别和所述每个第二采样序列的相关度；将所述第一组相关值中的峰值与第一预设门限值进行比较；当所述第一组相关值中的峰值大于所述第一预设门限值时，将与所述第一组相关值中的峰值对应的所述第二同步序列在所述同步信号中的位置作为与所述基站实现信号同步的起始位置。
结合第一方面，在第一方面的一种实现方式中，所述第一同步序列的长度p、所述第一采样序列的长度q、所述互质采样的两个质数M和N应满足：
Figure PCTCN2016096392-appb-000001
结合第一方面及其上述实现方式，在第一方面的另一种实现方式中，所述方法还包括：当所述第一组相关值中的峰值小于或者等于所述第一预设门限值时，将第一剩余序列与多个第二剩余序列分别进行互相关运算，得到第二组相关值，其中，所述第一剩余序列为对所述本地存储的第一同步序列进行互质采样后剩余的序列，所述第二剩余序列为对所述第四序列进行互质采样后剩余的序列，所述第二组相关值用来表示所述第一剩余序列分别和每个第二剩余序列的相关度；将所述第一组相关值和所述第二组相关值相加，得到第三组相关值，所述第三组相关值用来表示所述第一同步序列分别和每个所述第四序列的相关度；从所述第三组相关值中选取最大值确定为第三组相 关值的峰值；当所述第三组相关值的峰值大于第二预设门限值时，将所述第三组相关值的峰值对应的第二同步序列的位置作为与所述基站实现同步的起始位置。
第二方面，提供了一种信号同步的装置，包括：第一互质采样单元，用于对第一同步序列进行互质采样，得到第一采样序列，其中，所述第一同步序列存储在移动终端，所述互质采样为使用两个质数分别间隔均匀地对序列进行采样；解差分单元，用于对基站发送的同步信号携带的第二同步序列进行解差分运算，得到解差分序列；截取单元，用于从所述解差分单元得到的解差分序列中截取长度为预设值的多个第三序列；下采样单元，用于对所述截取单元得到的所述多个第三序列分别进行下采样，得到多个第四序列，其中，每个第四序列的长度与所述第一同步序列的长度相同；第二互质采样单元，用于对所述下采样单元得到的所述多个第四序列分别进行所述互质采样，得到多个第二采样序列；第一互相关运算单元，用于对所述第一采样单元得到的所述第一采样序列和所述第二互质采样单元得到的所述多个第二采样序列中的每个第二采样序列分别进行互相关运算，得到第一组相关值，其中，所述互相关运算为两个序列之间相对于时间的滑动点积，所述第一组相关值用来表示所述第一采样序列分别和所述每个第二采样序列的相关度；比较单元，用于将所述第一互相关运算单元得到的所述第一组相关值中的峰值与第一预设门限值进行比较；第一同步单元，用于当所述互相关运算单元得到的所述第一组相关值中的峰值大于所述第一预设门限值时，将与所述第一组相关值中的峰值对应的所述第二同步序列在所述同步信号中的位置作为与所述基站实现信号同步的起始位置。
结合第二方面，在第二方面的一种实现方式中，所述第一同步序列的长度p、所述第一采样序列的长度q、所述互质采样的两个质数M和N应满足：
Figure PCTCN2016096392-appb-000002
结合第二方面及其上述实现方式，在第二方面的另一种实现方式中，所述装置还包括：第二互相关运算单元，用于当所述第一组相关值中的峰值小于或者等于所述第一预设门限值时，将第一剩余序列与多个第二剩余序列分别进行互相关运算，得到第二组相关值，其中，所述第一剩余序列为对所述本地存储的第一同步序列进行互质采样后剩余的序列，所述第二剩余序列为 对所述第四序列进行互质采样后剩余的序列，所述第二组相关值用来表示所述第一剩余序列分别和每个第二剩余序列的相关度；叠加单元，用于将所述第一组相关值和所述第二组相关值相加，得到第三组相关值，所述第三组相关值用来表示所述第一同步序列分别和每个所述第四序列的相关度；确定单元，用于从所述第三组相关值中选取最大值确定为第三组相关值的峰值；第二同步单元，用于当所述第三组相关值的峰值大于第二预设门限值时，将所述第三组相关值的峰值对应的第二同步序列的位置作为与所述基站实现同步的起始位置。
第三方面，提供了一种移动终端，包括：存储器、接收器和处理器；所述存储器用于存储所述处理器执行的指令；所述处理器用于控制所述接收器接收基站发送的同步信号携带的第二同步序列；所述处理器还用于对第一同步序列进行互质采样得到第一采样序列，对所述第二同步序列进行解差分运算得到解差分序列，从所述解差分序列中截取长度为预设值的多个第三序列，对所述多个第三序列分别进行下采样得到多个第四序列，对所述多个第四序列分别进行所述互质采样得到多个第二采样序列，对所述第一采样序列和所述多个第二采样序列中的每个第二采样序列分别进行互相关运算得到第一组相关值，并将所述第一组相关值中的峰值与第一预设门限值进行比较，当所述第一组相关值中的峰值大于所述第一预设门限值时，将与所述第一组相关值中的峰值对应的所述第二同步序列在所述同步信号中的位置作为与所述基站实现信号同步的起始位置，其中，所述第一同步序列存储在移动终端，所述互质采样为使用两个质数分别间隔均匀地对序列进行采样，且，每个第四序列的长度与所述第一同步序列的长度相同，所述互相关运算为两个序列之间相对于时间的滑动点积，所述第一组相关值用来表示所述第一采样序列分别和所述每个第二采样序列的相关度。
结合第三方面，在第三方面的一种实现方式中，所述第一同步序列的长度p、所述第一采样序列的长度q、所述互质采样的两个质数M和N应满足：
Figure PCTCN2016096392-appb-000003
结合第三方面及其上述实现方式，在第三方面的另一种实现方式中，所述处理器还用于当所述第一组相关值中的峰值小于或者等于所述第一预设门限值时，将第一剩余序列与多个第二剩余序列分别进行互相关运算，得到 第二组相关值，将所述第一组相关值和所述第二组相关值相加得到第三组相关值，从所述第三组相关值中选取最大值确定为第三组相关值的峰值，当所述第三组相关值的峰值大于第二预设门限值时，将所述第三组相关值的峰值对应的第二同步序列的位置作为与所述基站实现同步的起始位置，其中，所述第一剩余序列为对所述本地存储的第一同步序列进行互质采样后剩余的序列，所述第二剩余序列为对所述第四序列进行互质采样后剩余的序列，所述第二组相关值用来表示所述第一剩余序列分别和每个第二剩余序列的相关度，所述第三组相关值用来表示所述第一同步序列分别和每个所述第四序列的相关度。
本发明实施例通过对本地同步序列和基站发送的同步序列解差分截取采样后的序列都进行互质采样，并根据互质采样后序列的互相关运算结果确定与基站实现同步的起始位置，这样可以避免直接对本地同步序列和解差分截取采样前的序列进行互相关运算确定同步起始位置带来的运算复杂度高的技术问题，从而能够降低运算复杂度。
附图说明
为了更清楚地说明本发明实施例的技术方案，下面将对本发明实施例中所需要使用的附图作简单地介绍，显而易见地，下面所描述的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1是本发明一个实施例的同步方法的示意性流程图。
图2是本发明另一实施例的同步方法的示意性流程图。
图3是本发明一个实施例的同步装置的框图。
图4是本发明另一实施例的同步装置的框图。
具体实施方式
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例是本发明的一部分实施例，而不是全部实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动的前提下所获得的所有其他实施例，都应属于本发明保护的范围。
本发明实施例中的移动终端(Mobile Terminal)可以称之为用户设备 (User Equipment，简称为“UE”)、终端(Terminal)、移动台(Mobile Station，简称为“MS”)等。移动终端可以是移动电话(或称为“蜂窝”电话)或具有移动终端的计算机等，例如，便携式、袖珍式、手持式、计算机内置的或者车载的移动装置。
图1是本发明一个实施例的同步方法的示意性流程图。图1的方法可以由移动终端执行。
101，对第一同步序列进行互质采样，得到第一采样序列，其中，第一同步序列存储在移动终端，互质采样为使用两个质数分别间隔均匀地对序列进行采样。
102，对基站发送的同步信号携带的第二同步序列进行解差分运算，得到解差分序列。
103，从解差分序列中截取数据长度为预设值的多个第三序列。
104，对多个第三序列进行下采样，得到多个第四序列，其中，每个第四序列的长度与第一同步序列的长度相同。
105，对多个第四序列分别进行互质采样，得到多个第二采样序列。
106，对第一采样序列和多个第二采样序列中的每个第二采样序列分别进行互相关运算，得到第一组相关值，其中，互相关运算为两个序列之间相对于时间的滑动点积，第一组相关值用来表示第一采样序列分别和每个第二采样序列的相关度。
107，将第一组相关值中的峰值与第一预设门限值进行比较。
108，当第一组相关值中的峰值大于第一预设门限值时，将与第一组相关值中的峰值对应的第二同步序列在所述同步信号中的位置作为与基站实现信号同步的起始位置。
本发明实施例通过对本地同步序列和基站发送的同步序列解差分截取采样后的序列都进行互质采样，并根据互质采样后序列的互相关运算结果确定与基站实现同步的起始位置，这样可以避免直接对本地同步序列和解差分截取采样前的序列进行互相关运算确定同步起始位置带来的运算复杂度高的技术问题，从而能够降低运算复杂度。
同步信号主要用于移动终端初始入网或者从休眠中醒来时进行帧信号检测、符号定时同步以及粗载波频偏估计。
可以通过下列方式产生本地同步信号(即第一同步序列所在的同步信 号)：首先，产生长度为255的m序列{ai|i＝0,…,254}，生成多项式为x8+x6+x5+x4+1，移位寄存器初始状态为{0,0,0,0,0,0,0,0,1}。接着，对m序列进行二进制相移键控(Binary Phase Shift Keying，BPSK)调制(‘0’映射为‘1’，‘1’映射为‘-1’)，得到BPSK序列{bi|i＝0,…,254}。最后，对BPSK序列进行差分运算，得到本地同步信号{PSSi+1＝PSSi*bi|i＝0,…,254}，其中，PSS0＝exp(j*π/4)。
本发明实施例中，主要使用了一种新型的数据采样方式即互质(co-prime)采样。这种采样方式可以在不丢失数据有效信息的情况下对数据进行采样，保证co-prime采样后的数据与原有数据具有一致性较好的自相关特性。即，在原有数据具有良好的自相关特性的情况下，co-prime采样后的数据也具有良好的自相关特性。co-prime采样使用M和N两个质数分别对数据x(n)进行均匀间隔采样，即可以将数据以M*N为一个采样周期进行分割。使用M和N两个质数分别采样时的采样速率都低于奈奎斯特采样速率，采样频率为
Figure PCTCN2016096392-appb-000004
由于co-prime采样后的数据长度与采样因子M和N有关，为了便于根据采样数据长度选取采样因子，原始序列(例如第一同步序列)的长度为p、co-prime采样后序列(例如第一采样序列)的长度为q、采样因子M和N应满足下列条件：
Figure PCTCN2016096392-appb-000005
也就是说，采样频率为采样后的序列长度与采样前序列长度之比。
举个例子，以
Figure PCTCN2016096392-appb-000006
为例，设采样前的原始数据长度为255，希望得到的采样后序列长度为119，则采样频率是
Figure PCTCN2016096392-appb-000007
由于M和N取值只能为质数，则M、N的取值可以如下：M＝3，N＝5，或M＝5，N＝3。
两组采样参数下的采样数据的自由度可表示为k＝Mn1-Nn2，当满足0≤n1≤N-1，且-M+1≤n2≤M-1时，自由度k可以取到{0，MN-1}内的任意整数值。
下面对co-prime采样进行具体阐述。对长度为N的数据x(n)进行co-prime采样，采样参数分别为M和N两个质数，则采样周期Tc为M*N。将数据x(n)按照采样周期Tc分割为若干段，若N恰好能被Tc整除，则x(n)每段内被分割为若干段均匀数据，每段内分别以采样参数M和N进行均匀采样。若N不能被Tc整除，则x(n)将被分割为若干段均匀数据和一段长度不足Tc的数据，每段内仍分别以采样参数M和N进行均匀采样。
下面以LTE-M的本地同步信号的co-prime采样做具体说明。假设x(n)为255点PSS时域序列，这里采样参数设置为M＝3,N＝5，那么co-prime采样周期可以表示为M*N＝15。在一个周期内分别以3和5两个参数进行均匀间隔下采样，得到采样后的序列：
{PSSj|j＝0,1,…，118}＝PSS0,PSS3,PSS5,PSS6,PSS9,PSS10,PSS12,...PSS252。
剩余序列为：
{PSSk|k＝0,1,…，135}＝PSS1,PSS2,PSS4,PSS7,PSS8,PSS11,PSS13,PSS14,...PSS254。
步骤101中的第一同步序列即上述的本地同步信号携带的序列。本地同步信号可以为移动终端预存在本地的信号。本地同步信号携带的第一同步序列可以为伪噪声(Pseudo-noise，PN)序列，伪噪声序列具有良好的随机性和接近于白噪声的相关特性。
在本发明的一个实施例中，移动终端可以根据基站发送的同步信号携带的第二同步序列确定多个新序列(例如，第四序列)。例如，移动终端可以对基站发送的同步信号携带的第二同步序列进行解差分运算，得到解差分序列。从解差分序列中截取数据长度为预设值的多个第三序列。并对多个第三序列进行预设的下采样，得到多个第四序列。
例如，移动终端可以接收基站发送的序列，并将上一帧的最后5120个采样点放在接收到的本帧数据之前，得到新序列{si|i＝0,1,...}。对该新序列进行解差分运算，得到解差分后的序列
Figure PCTCN2016096392-appb-000008
其中，i＝21,22,...，
Figure PCTCN2016096392-appb-000009
表示x的共轭。接着，以一定值x为步长，从解差分后的序列中依次截取数据长度为预设值的多个序列，其中，x为正整数。例如，依次截取的多个序列为[1:5100]，[x+1:x+5100]，[2x+1:2x+5100]……。然后，对多个序列都分别 进行下采样，例如，对序列[1:5100]中每20个采样值中取1个采样值，得到与本地序列数据点数相同的第四序列。
本发明实施例对采样倍数不做限定，例如，上述实施例中的数字20是系统可以预先设定的系统参数。基站向移动终端发送信号时对信号进行20倍的上采样，所以，移动终端接收基站发送的信号之后，对多个序列进行下采样时也进行20倍下采样，即每20个采样值中取1个采样值。当移动终端接收基站发送的信号时，数据中的1个数用20个采样点表示时，在对多个序列分别进行下采样的采样率设置为20，即可以从每20个采样值中选取1个采样值作为新的第四序列的采样点。
本发明实施例截取数据长度不做限定，这里仅以截取5100个数据点为例进行示例性说明。即，以本地序列为255个采样点、采样率为20为例，截取时可以截取5100个数据点。
在本发明的一个实施例中，对本地存储的第一同步序列进行互质采样的采样参数和对多个第四序列分别进行互质采样的采样参数相同。
co-prime采样的采样参数相同指的是采样时的两个质数M、N的值相同，即都是以质数M和N分别进行间隔均匀的采样。
互相关运算为两个序列之间相对于时间的滑动点积。例如，两个序列分别用f(t)和g(t)表示，则互相关运算可以定义为R(u)＝f(t)*g(-t)，其中，R(u)为互相关运算的结果。互相关运算的结果表示两个时间序列之间的相关程度，即互相关运算的结果时描述随机信号在任意两个不同时刻的取值之间的相关程度。
为进行互相关运算，需第一采样序列的长度与第二采样序列的长度相同。本发明的一个实施例中，采样前的每个第四序列的长度与第一同步序列的长度也需要相同，这样可以保证序列在位置上相匹配。
可选地，作为本发明的一个实施例，移动终端可以根据第一采样序列和多个第二采样序列的互相关运算结果确定第二同步序列中与基站实现同步的起始位置。例如，将第一采样序列与多个第二采样序列分别进行互相关运算，得到第一组相关值；将第一组相关值中的峰值与第一预设门限值进行比较；当第一组相关值中的峰值大于第一预设门限值时，将与该峰值对应的第二同步序列的位置作为与基站实现同步的起始位置。
进一步地，当第一组相关值中的峰值小于或者等于第一预设门限值时， 将第一剩余序列与多个第二剩余序列分别进行互相关运算，得到第二组相关值。将所述第一组相关值和所述第二组相关值相加，得到第三组相关值(即总的相关值)。从第三组相关值中选取最大值确定为第三组相关值的峰值。当第三组相关值的峰值大于第二预设门限值时，将第三组相关值的峰值对应的第二同步序列的位置作为与基站实现同步的起始位置。其中，第一剩余序列为对本地存储的第一同步序列进行互质采样后剩余的序列，第二剩余序列为对第四序列进行互质采样后剩余的序列，第二组相关值用来表示所述第一剩余序列分别和每个第二剩余序列的相关度，第三组相关值用来表示第一同步序列分别和每个第四序列的相关度。
具体地，移动终端可以使用本地采样序列(即第一采样序列)分别对多个接收采样序列(即第二采样序列)做互相关运算。当互相关运算得到的相关值的峰值大于第一预设门限值时，可以将该峰值相应的位置记为帧起始位置。当互相关运算得到的相关值的峰值小于或者等于第一预设门限值时，使用本地剩余序列(即第一剩余序列)分别对多个接收剩余序列(即第二剩余序列)做互相关运算。将两次互相关运算得到的相关值相加，得到第三组相关值，并从第三组相关值中选取最大值确定为总的相关峰值。将总的相关峰值与第二预设门限值比较。当总的相关峰值大于第二预设门限值时，可以将总的相关峰值对应的位置记为帧起始位置。当总的相关峰值小于或者等于第二预设门限值时，移动终端可以继续接收基站发送的下一帧数据，对下一帧数据进行同步检测。
应理解，本发明实施例中计算得到的峰值为临界点(例如，第一预设门限值、第二预设门限值)时的具体操作步骤可以判断为与基站实现同步的起始位置，也可以判断为不是同步的起始位置。例如，在本发明实施例中，也可以在当第一组相关值中的峰值大于或者等于第一预设门限值时，将与该峰值对应的第二同步序列的位置作为与基站实现同步的起始位置。而当第一组相关值中的峰值小于第一预设门限值时，将第一剩余序列与多个第二剩余序列分别进行互相关运算。
本发明实施例中的第一预设门限值和第二预设门限值是根据经验得到的经验值。例如，可以通过仿真找到同步的起始位置，并根据同步的起始位置对应的相关值设定第一预设门限值和第二预设门限值。
移动终端可以通过找出基站发送的序列中与移动终端本地存储的序列 相同或相似度很大的序列，这样来实现与基站之间的同步。两个序列的相关值越大，表示两个序列的相似度越大。所以，本发明实施例中要找出相关值中的最大值。但是，当相关值中的最大值仍未达到预设门限值时，认为无法实现同步。只有当相关值中的最大值大于预设门限值时，可以认为终端可以与基站之间实现同步。
本发明实施例中，对本地存储的序列和基站发送的序列都进行互质采样，这样可以使得互相关运算的数据量减少，降低计算复杂度，进而缩短同步时间。并且，经过互质采样后的序列自相关特性好，这样可以在降低计算复杂度的同时，仍保留序列良好的自相关特性，有利于移动终端与基站实现同步。
本发明实施例中，通过对序列进行互质采样由于采样点数减少，确定同步起始位置的精确度也相应降低。所以，降低运算复杂度是以牺牲一定的同步起始位置点的精度为代价的。但是，仿真结果表明，随着信噪比的提高，采用对序列进行互质采样的同步检测概率具有相当高的可靠性，即随着信噪比的提高，互质采样的同步检测概率(即互质检测概率)越来越接近对全部数据点进行互相关运算的同步检测概率(即现有检测概率)。这里的检测概率为能够同步上的概率。例如，频偏为500Hz、信噪比为-10db时，现有检测概率为0.48，互质检测概率为0.24。频偏为500Hz、信噪比为-7db时，现有检测概率为0.92，互质检测概率为0.94。频偏为500Hz、信噪比为-3db时，现有检测概率为0.97，互质检测概率为0.96。频偏为500Hz、信噪比为0db时，现有检测概率为0.98，互质检测概率为0.97。
在相同的频偏下，随着信噪比的增高，互质采样的同步方法得到的同步偏移为0的值越来越大，同步错误越来越小。
在相同的频偏下，互质采样的同步方法的运算复杂度相比对全部数据点进行互相关运算的运算复杂度越来越低。而且随着信噪比的增高，运算复杂度的差距越来越大。当信噪比大于-7db且小于0db范围内时，互质采样的同步方法的运算复杂度远远小于对全部数据点进行互相关运算的运算复杂度的一半。
本发明实施例中对序列进行互质采样相对于采用其它采样方式得到的序列具有更好的自相关特性，更有助于快速实现同步。例如，本发明实施例的同步方法对本地PN序列采用co-prime采样机制，可以在原数据具有良好 的自相关特性的基础上，保证采样后的数据仍具有良好的自相关特性，从而可以确保实现同步的检测性能，即在降低计算复杂度的同时对同步的概率影响不大。
下面结合具体例子更加详细地描述本发明的实施例。应注意，这些例子只是为了帮助本领域技术人员更好地理解本发明实施例，而非限制本发明实施例的范围。
图2是本发明另一实施例的同步方法的示意性流程图。本发明实施例仅以移动终端存储的本地同步信号的同步序列包括255个采样点，且系统预设的上采样倍数为20为例进行示例性说明。
201，接收基站发送的同步信号。
接收基站发送的同步信号，该同步信号携带接收同步序列(例如，第二同步序列)。假设同步信号的样点速率为240Ksps。
202，保存上一帧的最后5120个采样点放在接收到的本帧数据之前，并保存本帧的最后5120个采样点。
在同步序列的数据之前增加上一帧的最后5120个采样点，得到序列{si|i＝0,1,...}。
203，相邻符号的差分解调。
移动终端可以对序列{si|i＝0,1,...}进行解差分运算，得到解差分后的序列
Figure PCTCN2016096392-appb-000010
其中，i＝21,22,...，
Figure PCTCN2016096392-appb-000011
表示x的共轭。
204，从解差分后的序列中获取多个截短序列。
以预设值x为步长，从解差分后的序列中截取数据点数为5100的多个序列，并对多个序列进行下采样，每20个采样值取中一个采样值，得到多个数据点数为255的截短序列。
一般地，取步长x＝1。例如从解差分后的序列中依次截取得到数据点数为5100的多个序列：[1:5100]，[2:5101]，[3:5102]……。
对上述多个序列进行下采样，例如，每20个采样值取中一个采样值。例如，对序列[1:5100]下采样后得到的截短序列表示为{cq|q＝0,1,…,254}。具体地，可以为cq＝1,21,41,61,…，还可以为cq＝2,22,42,62,…等等。本发明对下采样具体取20个采样值中的第几个数据点不做限定。
205，对本地PN序列进行互质采样得到本地采样序列。
本地预先可以存储同步信号，同步信号中携带本地同步序列(例如，第 一同步序列){bi|i＝0,…,254}。本地同步序列可以为PN序列。移动终端可以对本地同步序列进行互质采样，得到本地采样序列(例如，第一采样序列)和本地剩余序列(例如，第一剩余序列)。
例如，对本地序列{bi|i＝0,…,254}进行互质采样，采样参数设置为M＝3,N＝5。互质采样后得到的本地采样序列为{bj|j＝0,1,…,118}，具体地，bj＝b0,b3,b5,b6,b9,b10,b12,…b252。本地剩余序列为{bk|k＝0,1,…,135}，具体地，bk＝b1,b2,b4,b7,b8,b11,b13,b14,…b254。
206，对多个截短序列进行互质采样得到接收采样序列。
移动终端可以对步骤204得到的多个截短序列进行互质采样得到接收采样序列(例如，第二采样序列)和接收剩余序列(例如，第二剩余序列)。这里仅以对序列[1:5100]下采样后得到的截短序列为{cq|q＝0,1,…,254}为例进行说明。
例如，对截短序列{cq|q＝0,1,…,254}进行互质采样，采样参数设置为M＝3,N＝5。互质采样后得到的接收采样序列为{rj|j＝0,1,…,118}，具体地，rj＝r′0,r′3,r′5,r′6,r′9,r′10,r′12,…r′252。接收剩余序列为{rk|k＝0,1,…,135}，具体地，rk＝r′1,r′2,r′4,r′7,r′8,r′11,r′13,r′14,…r′254。
步骤204得到多个截短序列，对多个截短序列进行互质采样后可以得到多个接收采样序列和多个接收剩余序列。
207，对本地采样序列和多个接收采样序列分别进行互相关运算。
移动终端可以对步骤205得到的本地采样序列和步骤206得到的多个接收采样序列分别进行互相关运算，得到一组互相关运算的相关值
Figure PCTCN2016096392-appb-000012
其中，h1为相关窗的索引或为第二同步序列的起始位置。
208，获取上述互相关运算的相关值中的第一峰值。
从步骤207得到的一组互相关运算的相关值中选取最大值作为第一相关峰值，即该数据帧内的相关峰值
Figure PCTCN2016096392-appb-000013
209，判断第一峰值是否大于第一预设门限值。
第一预设门限值为移动终端预先设定的门限值。移动终端可以对步骤208得到的第一峰值与第一预设门限值的大小进行比较。
210，第一峰值对应的位置即为同步的起始位置。
当步骤209判断得到第一峰值大于第一预设门限值时，将该峰值对应的第二同步序列的位置作为与基站实现同步的起始位置。
211，对本地剩余序列和多个接收剩余序列分别进行互相关运算。
当步骤209判断得到第一相关峰值小于或者等于第一预设门限值时，对本地剩余序列和多个接收剩余序列分别进行互相关运算，得到另一组互相关运算的相关值
Figure PCTCN2016096392-appb-000014
其中，h2为相关窗的索引或为第二同步序列的起始位置。
212，由两组相关值确定总的相关值。
可以由上述两组相关值确定总的相关值。例如，将步骤207得到的一组互相关运算的相关值和步骤211得到的另一组互相关运算的相关值相加，得到总的相关值：
Figure PCTCN2016096392-appb-000015
213，从总的相关值中选取最大值作为总的峰值。
从步骤212得到的总的相关值中选取最大值，并将该最大值确定为总的峰值(例如，第二峰值)。
214，判断总的峰值是否大于第二预设值。
第二预设门限值为移动终端预先设定的门限值。移动终端可以对步骤213得到的第二峰值与第二预设门限值的大小进行比较。
215，第二峰值对应的位置即为同步的起始位置。
当步骤214判断得到第二峰值大于第二预设门限值时，将第二峰值对应的第二同步序列的位置作为与基站实现同步的起始位置。
216，接收下一帧数据。
当步骤214判断得到第二峰值小于或者等于第二预设门限值时，接收下一帧数据信号，流程返回到步骤201。移动终端可以对下一帧数据信号进行同步检测，直至找到同步的起始位置。
上文中结合图1到图2，详细描述了根据本发明实施例的同步方法，下面将结合图3和图4描述根据本发明实施例的同步装置。
图3是本发明一个实施例的同步装置的框图。图3的装置可执行图1和图2的方法。图3的同步装置10可以为移动终端，包括第一互质采样单元11、解差分单元12、截取单元13、下采样单元14、第二互质采样单元15、第一互相关运算单元16、比较单元17、第一同步单元18。
第一互质采样单元11用于对第一同步序列进行互质采样得到第一采样序列，其中，第一同步序列存储在移动终端，互质采样为使用两个质数分别 间隔均匀地对序列进行采样。
解差分单元12用于对基站发送的同步信号携带的第二同步序列进行解差分运算，得到解差分序列。
截取单元13用于从解差分单元中得到的解差分序列中截取数据长度为预设值的多个第三序列。
下采样单元14用于对截取单元得到的多个第三序列分别进行下采样得到多个第四序列，其中，每个第四序列的长度与第一同步序列的长度相同。
第二互质采样单元15用于对下采样单元得到的多个第四序列分别进行互质采样得到多个第二采样序列。
第一互相关运算单元16用于对第一采样单元得到的第一采样序列和第二互质采样单元得到的多个第二采样序列中的每个第二采样序列分别进行互相关运算，得到第一组相关值。其中，互相关运算为两个序列之间相对于时间的滑动点积，第一组相关值用来表示第一采样序列分别和每个第二采样序列的相关度。
比较单元17用于将第一互相关运算单元得到的第一组相关值中的峰值与第一预设门限值进行比较。
第一同步单元18用于当互相关运算单元得到的第一组相关值中的峰值大于第一预设门限值时，将与第一组相关值中的峰值对应的第二同步序列在同步信号中的位置作为与基站实现信号同步的起始位置。
本发明实施例通过对本地同步序列和基站发送的同步序列解差分截取采样后的序列都进行互质采样，并根据互质采样后序列的互相关运算结果确定与基站实现同步的起始位置，这样可以避免直接对本地同步序列和解差分截取采样前的序列进行互相关运算确定同步起始位置带来的运算复杂度高的技术问题，从而能够降低运算复杂度。
可选地，作为一个实施例，第一同步序列的长度p、第一采样序列的长度q、互质采样的两个质数M和N应满足：
Figure PCTCN2016096392-appb-000016
可选地，作为一个实施例，装置还包括第二互相关运算单元、叠加单元、确定单元和第二同步单元。第二互相关运算单元用于当第一组相关值中的峰值小于或者等于第一预设门限值时，将第一剩余序列与多个第二剩余序列分 别进行互相关运算，得到第二组相关值。其中，第一剩余序列为对本地存储的第一同步序列进行互质采样后剩余的序列。第二剩余序列为对第四序列进行互质采样后剩余的序列。第二组相关值用来表示第一剩余序列分别和每个第二剩余序列的相关度。叠加单元用于将第一组相关值和第二组相关值相加得到第三组相关值，第三组相关值用来表示第一同步序列分别和每个第四序列的相关度。确定单元用于从第三组相关值中选取最大值确定为第三组相关值的峰值。第二同步单元用于当第三组相关值的峰值大于第二预设门限值时，将第三组相关值的峰值对应的第二同步序列的位置作为与基站实现同步的起始位置。
根据本发明实施例的同步装置可对应于本发明实施例的同步方法中的具体步骤，并且，该装置中的各个单元/模块和上述其他操作和/或功能分别为了实现图1和图2中所示方法的相应流程，为了简洁，在此不再赘述。
图4本发明一个实施例的移动终端的示意性框图。图4的移动终端20包括处理器21、存储器22和接收器24。处理器21可以控制接收器24接收信号，并可用于处理信号。存储器22可以包括只读存储器和随机存取存储器，并向处理器21提供指令和数据。移动终端20的各个组件通过总线系统23耦合在一起，其中总线系统23除包括数据总线之外，还包括电源总线、控制总线和状态信号总线。但是为了清楚说明起见，在图中将各种总线都标为总线系统23。
上述本发明实施例揭示的方法可以应用于处理器21中，或者由处理器21实现。在实现过程中，上述方法的各步骤可以通过处理器21中的硬件的集成逻辑电路或者软件形式的指令完成。处理器21可以是通用处理器、数字信号处理器、专用集成电路、现场可编程门阵列或者其他可编程逻辑器件、分立门或者晶体管逻辑器件、分立硬件组件，可以实现或者执行本发明实施例中的公开的各方法、步骤及逻辑框图。通用处理器可以是微处理器或者任何常规的处理器等。结合本发明实施例所公开的方法的步骤可以直接体现为硬件处理器执行完成，或者用处理器中的硬件及软件模块组合执行完成。软件模块可以位于随机存储器，闪存、只读存储器，可编程只读存储器或者电可擦写可编程存储器、寄存器等本领域成熟的存储介质中。该存储介质位于存储器22，处理器21读取存储器22中的信息，结合其硬件完成上述方法的步骤。
具体地，接收器24可以接收基站发送的同步信号携带的第二同步序列。处理器21可以对第一同步序列进行互质采样得到第一采样序列。其中，第一同步序列存储在移动终端，互质采样为使用两个质数分别间隔均匀地对序列进行采样。并对第二同步序列进行解差分运算，得到解差分序列。从解差分序列中截取长度为预设值的多个第三序列。对多个第三序列进行下采样得到多个第四序列，每个第四序列的长度与所述第一同步序列的长度相同。对多个第四序列分别进行互质采样得到多个第二采样序列。对第一采样序列和多个第二采样序列中的每个第二采样序列分别进行互相关运算，得到第一组相关值，其中，互相关运算为两个序列之间相对于时间的滑动点积，第一组相关值用来表示第一采样序列分别和每个第二采样序列的相关度。将第一组相关值中的峰值与第一预设门限值进行比较。当第一组相关值中的峰值大于第一预设门限值时，将与第一组相关值中的峰值对应的第二同步序列在同步信号中的位置作为与基站实现信号同步的起始位置。
本发明实施例通过对本地同步序列和基站发送的同步序列解差分截取采样后的序列都进行互质采样，并根据互质采样后序列的互相关运算结果确定与基站实现同步的起始位置，这样可以避免直接对本地同步序列和解差分截取采样前的序列进行互相关运算确定同步起始位置带来的运算复杂度高的技术问题，从而能够降低运算复杂度。
可选地，作为一个实施例，第一同步序列的长度p、第一采样序列的长度q、互质采样的两个质数M和N应满足：
Figure PCTCN2016096392-appb-000017
可选地，作为一个实施例，处理器21可以当第一组相关值中的峰值小于或者等于第一预设门限值时，将第一剩余序列与多个第二剩余序列分别进行互相关运算，得到第二组相关值。将第一组相关值和第二组相关值相加，得到第三组相关值。从第三组相关值中选取最大值确定为第三组相关值的峰值。当第三组相关值的峰值大于第二预设门限值时，将第三组相关值的峰值对应的第二同步序列的位置作为与基站实现同步的起始位置。其中，第一剩余序列为对本地存储的第一同步序列进行互质采样后剩余的序列，第二剩余序列为对第四序列进行互质采样后剩余的序列，第二组相关值用来表示第一剩余序列分别和每个第二剩余序列的相关度，第三组相关值用来表示第一同 步序列分别和每个第四序列的相关度。
本领域普通技术人员可以意识到，结合本文中所公开的实施例中描述的各方法步骤和单元，能够以电子硬件、计算机软件或者二者的结合来实现，为了清楚地说明硬件和软件的可互换性，在上述说明中已经按照功能一般性地描述了各实施例的步骤及组成。这些功能究竟以硬件还是软件方式来执行，取决于技术方案的特定应用和设计约束条件。本领域普通技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本发明的范围。
结合本文中所公开的实施例描述的方法或步骤可以用硬件、处理器执行的软件程序，或者二者的结合来实施。软件程序可以置于随机存储器(RAM)、内存、只读存储器(ROM)、电可编程ROM、电可擦除可编程ROM、寄存器、硬盘、可移动磁盘、CD-ROM、或技术领域内所公知的任意其它形式的存储介质中。
尽管通过参考附图并结合优选实施例的方式对本发明进行了详细描述，但本发明并不限于此。在不脱离本发明的精神和实质的前提下，本领域普通技术人员可以对本发明的实施例进行各种等效的修改或替换，而这些修改或替换都应在本发明的涵盖范围内。

Claims (9)

  1. 一种信号同步的方法，其特征在于，包括：
    对第一同步序列进行互质采样，得到第一采样序列，其中，所述第一同步序列存储在移动终端，所述互质采样为使用两个质数分别间隔均匀地对序列进行采样；
    对基站发送的同步信号携带的第二同步序列进行解差分运算，得到解差分序列；
    从所述解差分序列中截取长度为预设值的多个第三序列；
    对所述多个第三序列分别进行下采样，得到多个第四序列，其中，每个第四序列的长度与所述第一同步序列的长度相同；
    对所述多个第四序列分别进行所述互质采样，得到多个第二采样序列；
    对所述第一采样序列和所述多个第二采样序列中的每个第二采样序列分别进行互相关运算，得到第一组相关值，其中，所述互相关运算为两个序列之间相对于时间的滑动点积，所述第一组相关值用来表示所述第一采样序列分别和所述每个第二采样序列的相关度；
    将所述第一组相关值中的峰值与第一预设门限值进行比较；
    当所述第一组相关值中的峰值大于所述第一预设门限值时，将与所述第一组相关值中的峰值对应的所述第二同步序列在所述同步信号中的位置作为与所述基站实现信号同步的起始位置。
  2. 如权利要求1所述的方法，其特征在于，所述第一同步序列的长度p、所述第一采样序列的长度q、所述互质采样的两个质数M和N应满足：
    Figure PCTCN2016096392-appb-100001
  3. 如权利要求1或2所述的方法，其特征在于，所述方法还包括：
    当所述第一组相关值中的峰值小于或者等于所述第一预设门限值时，将第一剩余序列与多个第二剩余序列分别进行互相关运算，得到第二组相关值，其中，所述第一剩余序列为对所述本地存储的第一同步序列进行互质采样后剩余的序列，所述第二剩余序列为对所述第四序列进行互质采样后剩余的序列，所述第二组相关值用来表示所述第一剩余序列分别和每个第二剩余序列的相关度；
    将所述第一组相关值和所述第二组相关值相加，得到第三组相关值，所述第三组相关值用来表示所述第一同步序列分别和每个所述第四序列的相关度；
    从所述第三组相关值中选取最大值确定为第三组相关值的峰值；
    当所述第三组相关值的峰值大于第二预设门限值时，将所述第三组相关值的峰值对应的第二同步序列的位置作为与所述基站实现同步的起始位置。
  4. 一种信号同步的装置，其特征在于，包括：
    第一互质采样单元，用于对第一同步序列进行互质采样，得到第一采样序列，其中，所述第一同步序列存储在移动终端，所述互质采样为使用两个质数分别间隔均匀地对序列进行采样；
    解差分单元，用于对基站发送的同步信号携带的第二同步序列进行解差分运算，得到解差分序列；
    截取单元，用于从所述解差分单元中得到的所述解差分序列中截取长度为预设值的多个第三序列；
    下采样单元，用于对所述截取单元得到的所述多个第三序列分别进行下采样，得到多个第四序列，其中，每个第四序列的长度与所述第一同步序列的长度相同；
    第二互质采样单元，用于对所述下采样单元得到的所述多个第四序列分别进行所述互质采样，得到多个第二采样序列；
    第一互相关运算单元，用于对所述第一采样单元得到的所述第一采样序列和所述第二互质采样单元得到的所述多个第二采样序列中的每个第二采样序列分别进行互相关运算，得到第一组相关值，其中，所述互相关运算为两个序列之间相对于时间的滑动点积，所述第一组相关值用来表示所述第一采样序列分别和所述每个第二采样序列的相关度；
    比较单元，用于将所述第一互相关运算单元得到的所述第一组相关值中的峰值与第一预设门限值进行比较；
    第一同步单元，用于当所述互相关运算单元得到的所述第一组相关值中的峰值大于所述第一预设门限值时，将与所述第一组相关值中的峰值对应的所述第二同步序列在所述同步信号中的位置作为与所述基站实现信号同步的起始位置。
  5. 如权利要求4所述的装置，其特征在于，所述第一同步序列的长度p、 所述第一采样序列的长度q、所述互质采样的两个质数M和N应满足：
    Figure PCTCN2016096392-appb-100002
  6. 如权利要求4或5所述的装置，其特征在于，所述装置还包括：
    第二互相关运算单元，用于当所述第一组相关值中的峰值小于或者等于所述第一预设门限值时，将第一剩余序列与多个第二剩余序列分别进行互相关运算，得到第二组相关值，其中，所述第一剩余序列为对所述本地存储的第一同步序列进行互质采样后剩余的序列，所述第二剩余序列为对所述第四序列进行互质采样后剩余的序列，所述第二组相关值用来表示所述第一剩余序列分别和每个第二剩余序列的相关度；
    叠加单元，用于将所述第一组相关值和所述第二组相关值相加，得到第三组相关值，所述第三组相关值用来表示所述第一同步序列分别和每个所述第四序列的相关度；
    确定单元，用于从所述第三组相关值中选取最大值确定为第三组相关值的峰值；
    第二同步单元，用于当所述第三组相关值的峰值大于第二预设门限值时，将所述第三组相关值的峰值对应的第二同步序列的位置作为与所述基站实现同步的起始位置。
  7. 一种移动终端，其特征在于，包括：存储器、接收器和处理器；
    存储器，用于存储第一同步序列；
    处理器，用于对所述第一同步序列进行互质采样，得到第一采样序列，所述互质采样为使用两个质数分别间隔均匀地对序列进行采样；
    接收器，用于接收基站发送的同步信号携带的第二同步序列；
    所述处理器，还用于对所述第二同步序列进行解差分运算得到解差分序列，并从所述解差分序列中截取长度为预设值的多个第三序列；
    所述处理器，还用于对所述多个第三序列分别进行下采样得到多个第四序列，并对所述多个第四序列分别进行所述互质采样得到多个第二采样序列，每个所述第四序列的长度与所述第一同步序列的长度相同；
    所述处理器，还用于对所述第一采样序列和所述多个第二采样序列中的每个第二采样序列分别进行互相关运算得到第一组相关值，并将所述第一组相关值中的峰值与第一预设门限值进行比较，当所述第一组相关值中的峰值 大于所述第一预设门限值时，将与所述第一组相关值中的峰值对应的所述第二同步序列在所述同步信号中的位置作为与所述基站实现信号同步的起始位置，其中，所述互相关运算为两个序列之间相对于时间的滑动点积，所述第一组相关值用来表示所述第一采样序列分别和所述每个第二采样序列的相关度。
  8. 如权利要求7所述的移动终端，其特征在于，所述第一同步序列的长度p、所述第一采样序列的长度q、所述互质采样的两个质数M和N应满足：
    Figure PCTCN2016096392-appb-100003
  9. 如权利要求7或8所述的移动终端，其特征在于，所述处理器，还用于当所述第一组相关值中的峰值小于或者等于所述第一预设门限值时，将第一剩余序列与多个第二剩余序列分别进行互相关运算，得到第二组相关值，将所述第一组相关值和所述第二组相关值相加得到第三组相关值，从所述第三组相关值中选取最大值确定为第三组相关值的峰值，当所述第三组相关值的峰值大于第二预设门限值时，将所述第三组相关值的峰值对应的第二同步序列的位置作为与所述基站实现同步的起始位置，其中，所述第一剩余序列为对所述本地存储的第一同步序列进行互质采样后剩余的序列，所述第二剩余序列为对所述第四序列进行互质采样后剩余的序列，所述第二组相关值用来表示所述第一剩余序列分别和每个第二剩余序列的相关度，所述第三组相关值用来表示所述第一同步序列分别和每个所述第四序列的相关度。
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