LTE230 system downlink synchronization method and device

Abstract

The embodiment of the invention provides an LTE230 system downlink synchronization method and device. The method comprises the following steps: acquiring a received signal; performing PSS coarse synchronization detection according to the received signal and a generated local main synchronization signal, and determining a PSS coarse synchronization position and a cell intra-group identifier; performing PSS fine synchronization detection according to the received signal and the PSS coarse synchronization position, and determining a PSS fine synchronization position; and performing SSS synchronization detection according to the received signal and the PSS fine synchronization position, and determining a cell group identifier and a frame initial position. According to the synchronization signal generation method and the detection method provided by the invention, the complexity can be reduced, and the synchronization precision can be improved.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of communication technology, and in particular to a method and device for downlink synchronization of an LTE230 system. Background Art

[0002] TD-LTE230 electric power wireless private network is a wireless communication system dedicated to electric power systems. It integrates LTE technology and 230MHz spectrum propagation characteristics and is closely integrated with electric power business needs. 278 discrete frequency points of 25kHz in the 223MHz to 235MHz frequency band are authorized for the construction and use of electric power wireless private networks, which can avoid the periodic congestion problems that occur when using wireless public networks. The signals in this frequency band have the advantages of strong diffraction capability, long-distance propagation, and wide coverage. Due to the discrete frequency points, the configurable bandwidth of the system is different from that of the LTE system, so a special physical layer frame structure is designed, and corresponding differentiated processing is also required during downlink synchronization. In the related technology, the downlink synchronization method of the LTE230 system and the generation and detection methods of the synchronization signal are relatively complex. Summary of the invention

[0003] In view of this, the purpose of the embodiments of the present application is to propose a method and device for downlink synchronization of an LTE230 system to solve the problem of downlink synchronization of the LTE230 system.

[0004] Based on the above purpose, the embodiment of the present application provides a LTE230 system downlink synchronization method, including: Get the received signal; Perform PSS coarse synchronization detection according to the received signal and the generated local primary synchronization signal to determine the PSS coarse synchronization position and the cell group internal identifier; Perform PSS fine synchronization detection according to the received signal and the PSS coarse synchronization position to determine the PSS fine synchronization position; According to the received signal and the PSS fine synchronization position, SSS synchronization detection is performed to determine the cell group identifier and the frame start position.

[0005] Optionally, the received signal includes a primary synchronization signal, and the method for generating the primary synchronization signal includes: According to the three preset root sequence index values, three groups of ZC sequences with a length of 222 points are generated; For each group of ZC sequences, a zero-padded sequence with a length of 224 points is obtained by padding the front and back with 0s, the zero-padded sequence is converted into time domain to obtain a zero-padded sequence in the time domain, the zero-padded sequence in the time domain is conjugated to obtain a conjugated sequence, the zero-padded sequence and the conjugated sequence in the time domain are connected in sequence to form a 448-point time domain signal, the 15-point time domain signal at the end of the time domain signal is selected as a cyclic prefix and added to the front of the time domain signal to obtain a main synchronization signal including 463 points.

[0006] Optionally, the method for generating the root sequence index value includes: Select an integer from 1-222 so that the ZC sequence generated according to the integer has the maximum autocorrelation and the minimum cross-correlation, and use the integer as the root sequence index value.

[0007] Optionally, the received signal includes a secondary synchronization signal, and the method for generating the secondary synchronization signal includes: Generate a sequence of length 62 points; The sequence is padded with 0s at the front and back to obtain a zero-padded sequence with a length of 64 points; Performing time domain conversion on the zero-padded sequence to obtain a zero-padded sequence in the time domain; Connect the 7 groups of zero-filled sequences in the time domain in sequence to form a 448-point time domain signal; The 14-point time domain signal at the end of the time domain signal is selected as a cyclic prefix and added to the front of the time domain signal to obtain a secondary synchronization signal including 462 points.

[0008] Optionally, the received signal includes at least two frames of data, and the local primary synchronization signal includes three groups of local primary synchronization signals with different cell group identifiers; performing PSS coarse synchronization detection according to the received signal and the generated local primary synchronization signal to determine the PSS coarse synchronization position and the cell group identifier, including: Dividing the received signal into a plurality of signal segments having overlapping areas; Performing frequency deviation correction on multiple signal segments respectively to obtain corrected multiple signal segments; Correlation operations are performed on each signal segment with three groups of local main synchronization signals to obtain corresponding correlation values; Determine the peak value corresponding to each segment of the signal according to the correlation value corresponding to each segment of the signal and the preset threshold value; The maximum peak value is selected from the peak values ​​corresponding to each segment signal, and the PSS coarse synchronization position and the cell group identifier are determined according to the maximum peak value.

[0009] Optionally, the received signal is divided into a plurality of signal segments having overlapping areas, the method being: Divide the received signal of length L into n segments. Two adjacent segments have an overlapping area. The length of the overlapping area is b. Then the length of each segment is ; If the length of the last signal is less than , then add 0 after the signal segment until the length is .

[0010] Optionally, performing PSS fine synchronization detection according to the received signal and the PSS coarse synchronization position to determine the PSS fine synchronization position includes: Taking the PSS coarse synchronization position as the center, selecting a predetermined number of data points from the received signal; Performing a correlation operation on the selected data point and the local primary synchronization signal corresponding to the identifier in the cell group to obtain a correlation value; The PSS fine synchronization position is determined according to the correlation value.

[0011] Optionally, performing SSS synchronization detection according to the received signal and the PSS fine synchronization position to determine the cell group identifier and the frame start position includes: Based on the PSS fine synchronization position, determining a secondary synchronization signal range including a secondary synchronization signal from the received signal; Calculate the cross-correlation value between the signal within the auxiliary synchronization signal range and the generated local auxiliary synchronization signal by using a coherent detection method; According to the mutual correlation value, a cell group identifier and a frame start position are determined.

[0012] Optionally, based on the PSS fine synchronization position, determining a secondary synchronization signal range including a secondary synchronization signal from the received signal comprises: If the data length before the PSS fine synchronization position is less than a preset length threshold, in the fifth subframe of the frame where the PSS fine synchronization position is located, a first number of data points are selected from the tail, and a second number of data points are selected from the starting position in the next frame received signal, and the first number of data points and the second number of data points are used as the auxiliary synchronization signal range; If the data length before the PSS fine synchronization position is greater than or equal to the length threshold, data points of the length threshold are taken forward from the PSS fine synchronization position as the auxiliary synchronization signal range.

[0013] The embodiment of the present application also provides a LTE230 system downlink synchronization device, including: An acquisition module, used for acquiring a received signal; A coarse synchronization detection module, used to perform PSS coarse synchronization detection according to the received signal and the generated local primary synchronization signal, and determine the PSS coarse synchronization position and the cell group internal identifier; A fine synchronization detection module, used to perform PSS fine synchronization detection according to the received signal and the PSS coarse synchronization position, and determine the PSS fine synchronization position; The auxiliary synchronization detection module is used to perform SSS synchronization detection according to the received signal and the PSS fine synchronization position, and determine the cell group identifier and the frame start position.

[0014] From the above, it can be seen that the LTE230 system downlink synchronization method and device provided in the embodiment of the present application performs PSS coarse synchronization detection according to the received signal and the generated local main synchronization signal, determines the PSS coarse synchronization position and the cell group identifier, performs PSS fine synchronization detection according to the received signal and the PSS coarse synchronization position, determines the PSS fine synchronization position, and performs SSS synchronization detection according to the received signal and the PSS fine synchronization position to determine the cell group identifier and the frame start position. The synchronization signal generation method and detection method provided in the present application can reduce complexity and improve synchronization accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 A schematic diagram of a method flow of an embodiment of the present application; Figure 2 This is a schematic diagram of the frame structure of the LTE230 system according to an embodiment of the present application; Figure 3 This is a schematic diagram of the frame structure in the time domain of an embodiment of the present application; Figure 4 A schematic diagram of overlapping segmented data according to an embodiment of the present application; Figure 5 This is a block diagram of the device structure of an embodiment of the present application; Figure 6 This is a structural block diagram of an electronic device according to an embodiment of the present application. DETAILED DESCRIPTION

[0017] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0018] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present application should be the usual meanings understood by people with ordinary skills in the field to which the present disclosure belongs. The "first", "second" and similar words used in the embodiments of the present application do not represent any order, quantity or importance, but are only used to distinguish different components. "Including" or "comprising" and similar words mean that the elements or objects appearing in front of the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connecting" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to represent relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0019] As described in the background technology section, there are differences in the frequency points, frame structures, etc. between the LTE230 system and the LTE system, and the generation methods of the primary synchronization signal (PSS) and the secondary synchronization signal (SSS) are also different. According to the relevant technical standards of LTELTE230 power wireless private network, the generation method of the PSS synchronization signal is to first generate a ZC sequence (i.e., Zadoff-Chu sequence) with a length of 62 points, divide the generated sequence into 7 segments, and each segment has a length of 4, 11, 11, 11, 11, 11, and 3 subcarriers, respectively, map the 7 subcarriers to 7 OFDM symbols, perform 64-point IFFT transformation on the frequency domain data of the 7 OFDM symbols, connect the converted 7 groups of time domain signals in sequence to form a time domain signal of 448 sampling points, and then add the time domain signal corresponding to the last 15 sampling points as a cyclic prefix to the front of the time domain signal of 448 sampling points to generate a PSS synchronization baseband signal in the time domain. The SSS synchronization signal is generated by interlacing and concatenating two binary sequences of 31 data points in length, segmenting, mapping, and IFFT transforming the sequences according to the method of generating the PSS synchronization signal, and then sequentially connecting the converted time domain signals to form a time domain signal of 448 sampling points, and then adding the time domain signals corresponding to the last 14 sampling points as cyclic prefixes to the front of the time domain signal of 448 sampling points to generate the SSS synchronization baseband signal in the time domain. The above synchronization signal generation method is relatively complicated, and splitting the ZC sequence will destroy the constant amplitude zero autocorrelation characteristics of the sequence. In addition, the downlink synchronization signal detection method used in the LTE system is also relatively complicated, and there is little research on the downlink synchronization signal detection method for the LTE230 system.

[0020] In view of this, an embodiment of the present application provides a downlink synchronization method for an LTE230 system. For the LTE230 system, a relatively simplified synchronization signal generation method is designed, and a corresponding downlink synchronization signal detection method is provided, which can achieve downlink synchronization, reduce the complexity of synchronization signal detection, and improve synchronization accuracy.

[0021] The technical solution of the present application is further described in detail below through specific embodiments.

[0022] like Figure 1 As shown, the embodiment of the present application provides a downlink synchronization method for an LTE system, including: S101: Acquire a received signal; In this embodiment, when the communication terminal accesses the LTE230 power wireless private network, the cell downlink synchronization process in the cell search is performed based on the received signal, so that the communication terminal and the cell achieve time and frequency synchronization and detect the cell identifier. After determining the time and frequency parameters, the communication terminal can demodulate other system information in the downlink and transmit accurate uplink information. Among them, the received signal includes the primary synchronization signal and the secondary synchronization signal, and the cell group identifier is obtained through the primary synchronization signal , obtain the cell group identifier through the secondary synchronization signal , and then determine the cell ID according to the cell group ID and the cell group ID , expressed as , complete downlink synchronization.

[0023] S102: Perform PSS coarse synchronization detection according to the received signal and the generated local primary synchronization signal to determine the PSS coarse synchronization position and the cell group identifier; In this embodiment, the communication terminal receives a signal, generates a local primary synchronization signal, and performs PSS coarse synchronization detection according to the primary synchronization signal in the received signal and the local primary synchronization signal.

[0024] To reduce complexity, based on the frame structure of the LTE230 system, this embodiment provides a method for generating a synchronization signal, including generating a primary synchronization signal and a secondary synchronization signal. The method for generating the primary synchronization signal includes: According to the three preset root sequence index values, three groups of ZC sequences with a length of 222 points are generated; For each group of ZC sequences, a zero-padded sequence with a length of 224 points is obtained by padding the front and back with 0s, the zero-padded sequence is converted into time domain to obtain a zero-padded sequence in the time domain, the zero-padded sequence in the time domain is conjugated to obtain a conjugated sequence, the zero-padded sequence and the conjugated sequence in the time domain are connected in sequence to form a 448-point time domain signal, the 15-point time domain signal at the end of the time domain signal is selected as a cyclic prefix and added to the front of the time domain signal to obtain a main synchronization signal including 463 points.

[0025] Figure 2 The figure shows the frame structure of the LTE230 system. The duration of the wireless frame used for uplink and downlink transmission of the LTE230 system is 25ms. A wireless frame contains 5 subframes, each subframe has a duration of 5ms and contains 9 OFDM symbols. Among them, subframe 0 is a downlink subframe, subframes 2, 3, and 4 are uplink subframes, and subframe 1 is a special subframe. The special subframe includes three parts: DwPTS, UpPTS, and GP. DwPTS can be used to transmit downlink data, UpPTS can be used to transmit uplink data, and GP is a protection time slot. The lengths of the three parts of the special subframe can be flexibly configured according to actual conditions; the auxiliary synchronization signal occupies subframe 0, and the auxiliary synchronization signal is placed from the starting position of subframe 0. The main synchronization signal occupies part of subframe 0 and the DwPTS position in subframe 1. In this embodiment, the main synchronization signal is constructed by generating a ZC sequence. In order to maintain the best characteristics of the ZC sequence, its length needs to be an odd number or a prime number. Based on the frame structure of the LTE230 system and the position of the main synchronization signal in a frame of data, the length of the ZC sequence is 223 points. Since the DC carrier at the center of the frequency domain carrier is punctured, the actual length of the ZC sequence is 222. Therefore, according to the preset three root sequence index values ​​u, according to the ZC sequence generation formula, three groups of ZC sequences with a length of 222 points are generated, which are expressed as: (1) The method for determining the root sequence index value for generating the ZC sequence is to select an integer from 1-222 so that the autocorrelation of the ZC sequence generated according to the integer is the largest and the cross-correlation is the smallest, and the integer is used as the root sequence index value. According to this method, three different root sequence index values ​​are selected in turn, and three corresponding groups of ZC sequences are generated according to the three root sequence index values; at the same time, a corresponding relationship between the root sequence index value and the cell group identifier is established, that is, when =0, the corresponding root sequence index value is , =1, the corresponding root sequence index value is , =2, the corresponding root sequence index value is .

[0026] After constructing three groups of ZC sequences, for each group of ZC sequences, in order to maintain the central symmetry of the ZC sequence, on the basis of the 222-point ZC sequence, a zero-padding sequence with a length of 224 points is obtained by front and back padding with zeros; since each subband of the LTE230 system contains only 11 subcarriers and the frequency points are discrete, there is no need to perform frequency domain segmentation processing, and the zero-padding sequence is directly converted to the time domain, and the frequency domain signal is converted to the time domain signal to obtain a zero-padding sequence in the time domain; the zero-padding sequence in the time domain is conjugated to obtain a conjugate sequence; the zero-padding sequence and the conjugate sequence in the time domain are connected in sequence to form a 448-point time domain signal; the 15-point time domain signal at the end of the time domain signal is selected as a cyclic prefix and added to the front of the time domain signal to obtain a main synchronization signal including 463 points. According to the above-mentioned ZC sequence processing method, three groups of main synchronization signals including 463 points are obtained. Compared with the main synchronization signal generation method in the related art, the method of this embodiment can reduce complexity and improve synchronization performance.

[0027] In some embodiments, the method of generating a secondary synchronization signal includes: Generate a sequence of length 62 points; The sequence is padded with 0s at the front and back to obtain a zero-padded sequence with a length of 64 points; Performing time domain conversion on the zero-padded sequence to obtain a zero-padded sequence in the time domain; Connect the 7 groups of zero-filled sequences in the time domain in sequence to form a 448-point time domain signal; The 14-point time domain signal at the end of the time domain signal is selected as a cyclic prefix and added to the front of the time domain signal to obtain a secondary synchronization signal including 462 points.

[0028] In this embodiment, for the auxiliary synchronization signal, two binary sequences with a length of 31 points are first generated according to the method in the LTE230 related standard (the two binary sequences are from the same m-sequence), and the two sequences are interlaced and concatenated to form a 62-point sequence; then, no segmentation processing is performed, but a zero-padded sequence with a length of 64 points is obtained by padding the 62-point sequence with zeros at the front and back; the zero-padded sequence is converted into the time domain, and the zero-padded sequence in the time domain is obtained by IFFT transformation; seven groups of zero-padded sequences in the time domain are constructed, and the seven groups of zero-padded sequences are connected in a front and back order to form a time domain signal with a length of 448 points; the 14-point time domain signal at the end of the time domain signal is selected as a cyclic prefix and added to the front of the time domain signal to obtain an auxiliary synchronization signal including 462 points; at the same time, a corresponding relationship between the m-sequence and the cell group identifier is established, which is not specifically listed in this embodiment.

[0029] like Figure 3As shown, based on the frame structure, after the primary synchronization signal and the secondary synchronization signal are generated, the secondary synchronization signal (SSS signal) is placed from the starting position of subframe 0, and the primary synchronization signal (PSS signal) is placed after the secondary synchronization signal. The communication terminal and the LTE system perform synchronization detection based on the synchronization signal of this frame structure. In some methods, 1 frame of data includes 5 subframes, each subframe is 5ms long, and contains 640 data points. The SSS signal is placed from the starting position of subframe 0, with a length of 462 points and a 14-point cyclic prefix, that is, points 0-461 are SSS signals. The PSS signal is placed from point 462, with a length of 463 points. The PSS signal contains a 15-point cyclic prefix. The 285 data points in the PSS signal occupy the DwPTS area in subframe 1. Except for the GP, the remaining positions are used to transmit uplink data.

[0030] In some embodiments, the received signal should include a synchronization signal in order to detect the synchronization signal. Therefore, in order to ensure that the received signal contains a primary synchronization signal, the received signal includes at least two frames of data, that is, at least two frames of data need to be received. At the same time, the communication terminal generates three groups of local primary synchronization signals with different cell group identifiers according to the three root sequence index values ​​established in this embodiment. The communication terminal performs PSS coarse synchronization detection based on the received signal and the generated local primary synchronization signal to determine the PSS coarse synchronization position and the cell group identifier. The method includes: Dividing the received signal into a plurality of signal segments with overlapping areas; Performing frequency deviation correction on multiple signal segments respectively to obtain corrected multiple signal segments; Correlation operations are performed on each signal segment with three groups of local main synchronization signals to obtain corresponding correlation values; Determine the peak value corresponding to each signal segment according to the correlation value corresponding to each signal segment and the preset threshold value; The maximum peak value is selected from the peak values ​​corresponding to each segment signal, and the PSS coarse synchronization position and the cell group identifier are determined according to the maximum peak value.

[0031] In this embodiment, the main synchronization signal is detected based on the overlapping segmentation method on the basis of the received signal. The overlapping segmentation method is to divide the received signal into multiple signal segments, and the multiple signal segments have overlapping areas. In order to reduce the influence of frequency deviation, the multiple signal segments are corrected for frequency deviation respectively to obtain the corrected multiple signal segments, and each signal segment is correlated with three groups of local main synchronization signals to obtain corresponding correlation values; then, according to the correlation values ​​corresponding to each signal segment and the preset threshold value, the peak value corresponding to each signal segment is determined; the maximum value is selected from the peak values ​​corresponding to each signal segment as the maximum peak value, and the PSS coarse synchronization position and the cell group identifier are determined according to the maximum peak value.

[0032] Specifically, Figure 4 As shown in the figure, assuming that the length of the received signal is L, the received signal is divided into n segments, and two adjacent segments have an overlapping area, and the length of the overlapping area is b, then the length of each segment is , if the length of the last signal is less than , then add 0 after the signal to get the length In some methods, the length of the received signal, the number of segments, the length of the overlapping area, etc. can be adjusted according to actual conditions. The more segments there are, the lower the complexity, but the weaker the anti-noise ability. The number of segments of the signal can be determined comprehensively based on the complexity and anti-noise performance. The length of the overlapping area should be an integer multiple of the OFDM symbol length and greater than the main synchronization signal length.

[0033] like Figure 4 As shown in some embodiments, for convenience of explanation, the received signal is two frames of data, the length of the received signal is L = 6400 points, the number of signal segments is n = 3, the length of the overlapping area is b = 640 points, then the length of each signal segment is =2560 points, and the starting position of each signal segment is {0, 1920, 3840} respectively.

[0034] In order to reduce the impact of frequency deviation on the correlation of the main synchronization signal, a set of frequency deviation values ​​is preset. For each segment of the divided signal, the segment of the signal is multiplied by the frequency deviation value to obtain the segment of the signal after the frequency deviation is corrected. The segment of the signal after the frequency deviation is corrected is respectively subjected to time domain correlation processing with the three groups of local main synchronization signals to obtain correlation values. According to this method, the correlation values ​​of each segment of the signal and each group of local main synchronization signals are calculated. Each segment of the signal corresponds to three groups of correlation values, and n segments of the signal correspond to 3n groups of correlation values.

[0035] In some methods, in order to reduce complexity, time domain correlation processing can be converted into frequency domain correlation processing, that is, the linear correlation in the time domain is converted into a circular convolution operation in the frequency domain. Before the circular convolution is run, each signal segment and the local main synchronization signal need to be padded with zeros according to the set circular convolution length. The calculation methods of the frequency deviation and the correlation value are not described in detail.

[0036] In some implementations, after calculating a set of correlation values ​​between a segment of signal and any group of local master synchronization signals, for any correlation value in a set of correlation values, the final correlation value corresponding to the correlation value is obtained by calculating the peak-to-average ratio or obtaining the square of the complex modulus of the correlation value. A set of final correlation values ​​corresponding to a set of correlation values ​​is calculated in this way, and each value in the set of final correlation values ​​is compared with a preset threshold value, and the largest final correlation value that exceeds the threshold value is taken as the peak value of the segment of signal. The peak value of each segment of signal is determined in the above method, and the maximum peak value and the segment of signal corresponding to the maximum peak value are determined therefrom, and the PSS coarse synchronization position and the cell group internal identifier are determined according to the peak position of the segment of signal.

[0037] In some methods, in order to improve the hardware processing efficiency and the real-time performance of the hardware calculation, each final correlation value in a group of final correlation values ​​is compared with a preset threshold value, so as to determine the peak value by sequentially taking a final correlation value from the group of final correlation values, comparing the final correlation value with the threshold value, if it is less than the threshold value, continuing to select the next final correlation value, if it is greater than the threshold value, recording the current final correlation value, continuing to select the next final correlation value and starting counting, adding one to the count for each comparison of a final correlation value, if no final correlation value greater than the current final correlation value is found when the count reaches a predetermined value, then the current final correlation value is taken as the peak value, which can eliminate the influence of the secondary peak and ensure real-time performance. Optionally, the predetermined value of the count can be set according to the actual situation, for example, it can be set to 120.

[0038] In some methods, the threshold value can be determined by deriving the threshold value using the false alarm probability. It refers to the probability of judging the PSS correlation peak without signal transmission in the case of noise interference. If the Gaussian white noise obeys (0, ) distribution, then the false alarm probability , N is the number of IFFT points when linear correlation occurs, and the threshold value is In another method, the threshold value can be determined by calculating the dynamic threshold value based on the actual noise power. The specific method is not described in detail.

[0039] S103: Perform PSS fine synchronization detection according to the received signal and the PSS coarse synchronization position to determine the PSS fine synchronization position; In this embodiment, after PSS coarse synchronization, affected by factors such as frequency offset and noise, the PSS coarse synchronization position has a position deviation of about half the cyclic prefix length from the actual synchronization position, and may be before or after the actual synchronization position. Therefore, after determining the PSS coarse synchronization position, secondary synchronization is further performed based on the received signal and the PSS coarse synchronization position to determine the PSS fine synchronization position and improve synchronization accuracy.

[0040] In some embodiments, determining the PSS fine synchronization position according to the received signal and the PSS coarse synchronization position includes: A predetermined number of data points are selected from the received signal with the PSS coarse synchronization position as the center; Perform correlation operation on the selected data points and the local main synchronization signal to obtain a correlation value; The PSS fine synchronization position is determined based on the correlation value.

[0041] This embodiment provides a method for determining the PSS fine synchronization position. Specifically, taking the PSS coarse synchronization position as the center, a received signal with a length of 15 points is selected, that is, taking the data point where the PSS coarse synchronization position is located as the center point, 7 data points are selected forward and 7 data points are selected backward, and the selected 15 data points are subjected to time domain correlation calculation with a group of local main synchronization signals corresponding to the cell group identifier determined by PSS coarse synchronization to obtain a group of correlation values, and a group of final correlation values ​​corresponding to the group of correlation values ​​are obtained by calculating the peak-to-average ratio or taking the square of the complex modulus of the correlation value, and the largest final correlation value is determined from the group of final correlation values ​​as the peak value, and the PSS fine synchronization position, that is, the precise timing synchronization position, is determined according to the position of the peak value.

[0042] S104: Perform SSS synchronization detection based on the received signal and the PSS fine synchronization position to determine the cell group identifier and the frame start position.

[0043] In this embodiment, in the LTE230 system, a frame of data includes a primary synchronization signal and a secondary synchronization signal, and the secondary synchronization signal is located at the frame header. Therefore, SSS synchronization detection is performed after PSS synchronization detection. On the one hand, the cell group identifier can be detected to obtain the complete cell number. On the other hand, the frame header position and the overall position of the frame can be accurately determined to improve the timing synchronization accuracy.

[0044] Among them, performing SSS synchronization detection according to the received signal and the PSS fine synchronization position includes: Based on the PSS fine synchronization position, determine a secondary synchronization signal range including the secondary synchronization signal from the received signal; Calculate the cross-correlation value between the signal within the auxiliary synchronization signal range and the generated local auxiliary synchronization signal by using a coherent detection method; According to the cross-correlation value, the cell group identifier and the frame start position are determined.

[0045] In this embodiment, combined with the positions of the primary synchronization signal and the secondary synchronization signal in the frame structure, after determining the PSS fine synchronization position, the approximate range of the secondary synchronization signal in the received signal can be determined. The specific method is: if the data length before the PSS fine synchronization position is less than the preset length threshold, the frame structure of the received data is inferred and calculated based on the PSS synchronization position, and in the fifth subframe of the frame where the PSS fine synchronization position is located, a first number of data points are selected from the tail, and then a second number of data points are selected from the starting position in the next frame of the received signal, and the first number of data points and the second number of data points are used as the range of the secondary synchronization signal. If the data length before the PSS fine synchronization position is greater than or equal to the length threshold, data points of the length threshold are taken from the PSS fine synchronization position forward as the range of the secondary synchronization signal.

[0046] Among them, the length threshold can be determined according to the frame position and subframe length. The length threshold should be greater than the sum of the length of the auxiliary synchronization signal (462 points) and the length of the cyclic prefix (14 points), that is, greater than 476 points. The length threshold should be determined by comprehensively considering the synchronization rate and error performance. The sum of the first number and the second number should also be greater than the sum of the length of the auxiliary synchronization signal and the length of the cyclic prefix. Optionally, the length threshold is set to 600 points, the first number is set to 140 points, and the second number is set to 500 points.

[0047] After determining the secondary synchronization signal range including the secondary synchronization signal, a coherent detection algorithm or other detection method is used to perform cross-correlation calculation on the signal within the secondary synchronization signal range and the generated local secondary synchronization signal, and the index value of the secondary synchronization signal is determined according to the cross-correlation peak value to achieve synchronization of the secondary synchronization signal, thereby obtaining the accurate position of the cell group identifier and the frame start. In some embodiments, the local secondary synchronization signal is generated by the communication terminal on the terminal side using the secondary synchronization signal generation method of this embodiment.

[0048] In some methods, considering that the time domains of the primary synchronization signal and the secondary synchronization signal in the frame structure are very close, after determining the PSS fine synchronization position, the PSS can be used to estimate the impulse response of the channel, and the secondary synchronization signal can be compensated for the channel according to the estimated impulse response before performing synchronization detection of the secondary synchronization signal. In some methods, after frame synchronization, the channel can be estimated by using the locally generated pilot and the received signal, so as to further obtain accurate frequency synchronization information, perform frequency offset compensation, and achieve frequency synchronization.

[0049] The LTE230 system downlink synchronization method provided in this embodiment is based on the frame structure of the LTE system. On the basis of not destroying the autocorrelation and cross-correlation characteristics of the ZC sequence, a main synchronization signal generation method and an auxiliary synchronization signal generation method with low complexity are designed; based on the frame structure and the generated main synchronization signal, an overlapping segmentation method is provided to perform synchronization detection of the main synchronization signal, which can reduce the complexity, reduce the impact of frequency deviation, and improve synchronization accuracy; after the main synchronization signal is detected, shorter data points are selected from the received signal through channel estimation and compensation to perform auxiliary synchronization signal detection, which can reduce the calculation complexity and improve the detection accuracy of the auxiliary synchronization signal.

[0050] It should be noted that the method of the embodiment of the present application can be performed by a single device, such as a computer or server. The method of this embodiment can also be applied to a distributed scenario and completed by multiple devices cooperating with each other. In the case of such a distributed scenario, one of the multiple devices can only perform one or more steps in the method of the embodiment of the present application, and the multiple devices will interact with each other to complete the described method.

[0051] It should be noted that the above is a description of a specific embodiment of the present specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0052] like Figure 5 As shown, the LTE230 system downlink synchronization device provided in the embodiment of the present application includes: An acquisition module, used for acquiring a received signal; A coarse synchronization detection module, used to perform PSS coarse synchronization detection according to the received signal and the generated local primary synchronization signal, and determine the PSS coarse synchronization position and the cell group internal identifier; A fine synchronization detection module is used to perform PSS fine synchronization detection according to the received signal and the PSS coarse synchronization position, and determine the PSS fine synchronization position; The auxiliary synchronization detection module is used to perform SSS synchronization detection based on the received signal and the PSS fine synchronization position to determine the cell group identifier and the frame start position.

[0053] For the convenience of description, the above devices are described in terms of functions divided into various modules. Of course, when implementing the embodiments of the present application, the functions of each module can be implemented in the same or multiple software and / or hardware.

[0054] The apparatus of the above-mentioned embodiment is used to implement the corresponding method in the above-mentioned embodiment, and has the beneficial effects of the corresponding method embodiment, which will not be described in detail here.

[0055] Figure 6 A more specific schematic diagram of the hardware structure of an electronic device provided in this embodiment is shown, and the device may include: a processor 1010, a memory 1020, an input / output interface 1030, a communication interface 1040, and a bus 1050. The processor 1010, the memory 1020, the input / output interface 1030, and the communication interface 1040 are connected to each other through the bus 1050 in the device.

[0056] The processor 1010 can be implemented by a general-purpose CPU (Central Processing Unit), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits, and is used to execute relevant programs to implement the technical solutions provided in the embodiments of this specification.

[0057] The memory 1020 may be implemented in the form of ROM (Read Only Memory), RAM (Random Access Memory), static storage device, dynamic storage device, etc. The memory 1020 may store an operating system and other application programs. When the technical solutions provided in the embodiments of this specification are implemented by software or firmware, the relevant program codes are stored in the memory 1020 and are called and executed by the processor 1010.

[0058] The input / output interface 1030 is used to connect the input / output module to realize information input and output. The input / output module can be configured in the device as a component (not shown in the figure), or it can be externally connected to the device to provide corresponding functions. The input device may include a keyboard, a mouse, a touch screen, a microphone, various sensors, etc., and the output device may include a display, a speaker, a vibrator, an indicator light, etc.

[0059] The communication interface 1040 is used to connect a communication module (not shown) to realize communication interaction between the device and other devices. The communication module can realize communication through wired means (such as USB, network cable, etc.) or wireless means (such as mobile network, WIFI, Bluetooth, etc.).

[0060] The bus 1050 includes a path that transmits information between the various components of the device (eg, the processor 1010 , the memory 1020 , the input / output interface 1030 , and the communication interface 1040 ).

[0061] It should be noted that, although the above device only shows the processor 1010, the memory 1020, the input / output interface 1030, the communication interface 1040 and the bus 1050, in the specific implementation process, the device may also include other components necessary for normal operation. In addition, it can be understood by those skilled in the art that the above device may also only include the components necessary for implementing the embodiments of the present specification, and does not necessarily include all the components shown in the figure.

[0062] The electronic device of the above embodiment is used to implement the corresponding method in the above embodiment, and has the beneficial effects of the corresponding method embodiment, which will not be described in detail here.

[0063] The computer-readable medium of this embodiment includes permanent and non-permanent, removable and non-removable media, and information storage can be implemented by any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, read-only compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device.

[0064] A person of ordinary skill in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present disclosure (including the claims) is limited to these examples. Based on the concept of the present disclosure, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present application as described above, which are not provided in detail for the sake of simplicity.

[0065] In addition, to simplify the description and discussion, and in order not to make the embodiments of the present application difficult to understand, the known power / ground connections to the integrated circuit (IC) chip and other components may or may not be shown in the provided drawings. In addition, the device may be shown in the form of a block diagram to avoid making the embodiments of the present application difficult to understand, and this also takes into account the fact that the details of the implementation of these block diagram devices are highly dependent on the platform on which the embodiments of the present application are to be implemented (that is, these details should be fully within the scope of understanding of those skilled in the art). Where specific details (e.g., circuits) are set forth to describe exemplary embodiments of the present disclosure, it is obvious to those skilled in the art that the embodiments of the present application can be implemented without these specific details or with changes in these specific details. Therefore, these descriptions should be considered illustrative rather than restrictive.

[0066] Although the present disclosure has been described in conjunction with specific embodiments of the present disclosure, many alternatives, modifications and variations of these embodiments will be apparent to those skilled in the art from the foregoing description. For example, other memory architectures (e.g., dynamic RAM (DRAM)) may use the discussed embodiments.

[0067] The embodiments of the present application are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present application should be included in the scope of protection of the present disclosure.

Claims

1. A LTE230 system downlink synchronization method, characterized in that: include: Get the received signal; Perform PSS coarse synchronization detection according to the received signal and the generated local primary synchronization signal to determine the PSS coarse synchronization position and the cell group identifier; Perform PSS fine synchronization detection according to the received signal and the PSS coarse synchronization position to determine the PSS fine synchronization position; According to the received signal and the PSS fine synchronization position, SSS synchronization detection is performed to determine the cell group identifier and the frame start position.

2. The method according to claim 1, characterized in that: The received signal includes a primary synchronization signal, and the method for generating the primary synchronization signal includes: According to the three preset root sequence index values, three groups of ZC sequences with a length of 222 points are generated; For each group of ZC sequences, a zero-padded sequence with a length of 224 points is obtained by padding the front and back with 0s, the zero-padded sequence is converted into time domain to obtain a zero-padded sequence in the time domain, the zero-padded sequence in the time domain is conjugated to obtain a conjugated sequence, the zero-padded sequence and the conjugated sequence in the time domain are connected in sequence to form a 448-point time domain signal, the 15-point time domain signal at the end of the time domain signal is selected as a cyclic prefix and added to the front of the time domain signal to obtain a main synchronization signal including 463 points.

3. The method according to claim 2, characterized in that The method for generating the root sequence index value includes: Select an integer from 1-222 so that the ZC sequence generated according to the integer has the largest autocorrelation and the smallest cross-correlation, and use the integer as the root sequence index value.

4. The method according to claim 1, characterized in that: The received signal includes a secondary synchronization signal, and the method for generating the secondary synchronization signal includes: Generate a sequence of length 62 points; The sequence is padded with 0s at the front and back to obtain a zero-padded sequence with a length of 64 points; Performing time domain conversion on the zero-padded sequence to obtain a zero-padded sequence in the time domain; Connect the 7 groups of zero-filled sequences in the time domain in sequence to form a 448-point time domain signal; The 14-point time domain signal at the end of the time domain signal is selected as a cyclic prefix and added to the front of the time domain signal to obtain a secondary synchronization signal including 462 points.

5. The method according to claim 1, characterized in that The received signal includes at least two frames of data, and the local primary synchronization signal includes three groups of local primary synchronization signals with different cell group identifiers; Performing PSS coarse synchronization detection according to the received signal and the generated local primary synchronization signal to determine the PSS coarse synchronization position and the cell group internal identifier, including: Dividing the received signal into multiple signal segments with overlapping areas; Performing frequency deviation correction on multiple signal segments respectively to obtain corrected multiple signal segments; Correlation operations are performed on each signal segment with three groups of local main synchronization signals to obtain corresponding correlation values; Determine the peak value corresponding to each segment of the signal according to the correlation value corresponding to each segment of the signal and the preset threshold value; The maximum peak value is selected from the peak values ​​corresponding to each signal segment, and the PSS coarse synchronization position and the cell group identifier are determined according to the maximum peak value.

6. The method according to claim 5, characterized in that The received signal is divided into a plurality of signal segments with overlapping areas, the method being: Divide the received signal of length L into n segments. Two adjacent segments have an overlapping area. The length of the overlapping area is b. Then the length of each segment is ; If the length of the last signal is less than , then add 0 after the signal segment until the length is .

7. The method according to claim 1, characterized in that Performing PSS fine synchronization detection according to the received signal and the PSS coarse synchronization position to determine the PSS fine synchronization position includes: Taking the PSS coarse synchronization position as the center, selecting a predetermined number of data points from the received signal; Performing a correlation operation on the selected data point and the local primary synchronization signal corresponding to the identifier in the cell group to obtain a correlation value; The PSS fine synchronization position is determined according to the correlation value.

8. The method according to claim 1, characterized in that Performing SSS synchronization detection according to the received signal and the PSS fine synchronization position to determine the cell group identifier and the frame start position, including: Based on the PSS fine synchronization position, determining a secondary synchronization signal range including a secondary synchronization signal from the received signal; Calculate the cross-correlation value between the signal within the auxiliary synchronization signal range and the generated local auxiliary synchronization signal by using a coherent detection method; According to the mutual correlation value, a cell group identifier and a frame start position are determined.

9. The method according to claim 8, characterized in that Determining a secondary synchronization signal range including a secondary synchronization signal from the received signal based on the PSS fine synchronization position includes: If the data length before the PSS fine synchronization position is less than a preset length threshold, in the fifth subframe of the frame where the PSS fine synchronization position is located, a first number of data points are selected from the tail, and a second number of data points are selected from the starting position in the next frame received signal, and the first number of data points and the second number of data points are used as the auxiliary synchronization signal range; If the data length before the PSS fine synchronization position is greater than or equal to the length threshold, data points of the length threshold are taken forward from the PSS fine synchronization position as the auxiliary synchronization signal range.

10. A downlink synchronization device for an LTE230 system, characterized in that: include: An acquisition module, used for acquiring a received signal; A coarse synchronization detection module, used to perform PSS coarse synchronization detection according to the received signal and the generated local primary synchronization signal, and determine the PSS coarse synchronization position and the cell group internal identifier; A fine synchronization detection module, used to perform PSS fine synchronization detection according to the received signal and the PSS coarse synchronization position, and determine the PSS fine synchronization position; The auxiliary synchronization detection module is used to perform SSS synchronization detection according to the received signal and the PSS fine synchronization position to determine the cell group identifier and the frame start position.

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