Signal initial synchronization method in sniffer mode of 5G base station

Abstract

The invention provides a signal initial synchronization method in a 5G base station sniffer mode, which comprises the following steps: acquiring a local PSS sequence and a received signal, carrying out fragment cross-correlation detection on the received signal and the local PSS sequence, and screening a maximum peak value from a cross-correlation detection result of the local PSS sequence; taking the local PSS sequence corresponding to the maximum peak value as a reference peak value, and obtaining a peak value position of the reference peak value; constructing a detection PSS sequence, performing fragment cross-correlation detection on the received signal and the detection PSS sequence, and searching a peak value position of a reference peak value in a cross-correlation detection result of the detection PSS sequence to obtain a detection sequence peak value; and judging whether the initial synchronization of the signal is completed or not according to the detection sequence peak value on the reference peak value. Through the technical scheme of the invention, when the base station searches the synchronization signal, the inter-station interference can be eliminated, and the success rate of PSS search synchronization is obviously improved.

Description

Technical Field

[0001] This invention relates to the field of 5G NR base station equipment technology, and more specifically, to a method for initial signal synchronization in 5G base station sniffer mode. Background Technology

[0002] Currently, in the 5G NR Sniffer clock mode, the Sniffer baseband processing detects and searches for NR base station synchronization signals (SSBs) in a specific frequency band in the vicinity. Based on the detection results, the local base station performs phase adjustment to align the frame headers of the local station with those of the public network, thereby achieving synchronization with the synchronization base station.

[0003] Sniffer channel reception processing typically involves spectrum shifting, downsampling, PSS coarse synchronization, PSS fine synchronization, PSS / SSS / PBCH time-frequency conversion, PSS / SSS phase compensation, SSS synchronization, frequency offset estimation, and SSB index blind detection. During the PSS coarse synchronization process, interference from other NR cells may occur, leading to unreliable detection threshold judgments and causing synchronization detection failure. Summary of the Invention

[0004] In view of this, the present invention proposes a signal initial synchronization method in 5G base station sniffer mode to solve the problems existing in the prior art.

[0005] To achieve the above objectives, this invention proposes a method for initial signal synchronization in 5G base station sniffer mode, comprising: Acquire the local PSS sequence and the received signal, perform segment cross-correlation detection on the received signal and the local PSS sequence, and filter the maximum peak value from the cross-correlation detection results of the local PSS sequence; take the local PSS sequence corresponding to the maximum peak value as the reference peak value, and obtain the peak position of the reference peak value; Construct a detection PSS sequence, perform segment cross-correlation detection on the received signal and the detection PSS sequence, and find the peak position of the reference peak in the cross-correlation detection results of the detection PSS sequence to obtain the peak value of the detection sequence. The initial synchronization of the signal is determined by comparing the peak value of the detected sequence with the reference peak value.

[0006] Optionally, the number of detected PSS sequences is one or more, and the detected PSS sequences have low correlation with local PSS sequences.

[0007] Optionally, the local PSS sequence is a PSS sequence with NID=0, 1, 2.

[0008] Optionally, the segment cross-correlation detection employs sliding detection, which calculates the correlation between different segments of the received signal and the PSS sequence.

[0009] Optionally, the process of determining the baseline peak value based on the peak value of the detected sequence includes: Calculate the mean of the peak values ​​in the detection sequence, construct the maximum peak-to-average ratio (PAPR), multiply the mean and PAPR to obtain a threshold value, compare the threshold value with the reference peak value, and determine that the initial synchronization of the detection signal is complete when the reference peak value is greater than the threshold value; otherwise, it is not complete.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows: Through the technical solution implemented by this invention, the base station can eliminate inter-station interference when searching for synchronization signals, which significantly improves the success rate of PSS search and synchronization. Attached Figure Description

[0011] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. In the drawings: Figure 1 This is a schematic diagram of the conventional PSS coarse synchronization process in an embodiment of the present invention; Figure 2 This is a schematic diagram of the PSS coarse synchronization process provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the sliding correlation process in an embodiment of the present invention. Detailed Implementation

[0012] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0013] For the PSS coarse synchronization content in the Sniffer channel reception processing, during the PSS coarse synchronization process, three sets of sequences are used to detect data peaks, and the point with the highest peak is obtained. At the same position, the correlation peaks of the other two sets of sequences are used as the noise floor to determine whether the detection threshold has been reached, thus determining the PSS reliability. Figure 1 As shown, the specific process is as follows.

[0014] Input received signal: The input is the baseband time domain signal after spectrum shifting and downsampling.

[0015] Three PSS sequences (corresponding to NID2 = 0, 1, 2) defined by the protocol are used to perform sliding correlation detection calculations with the received signal. Three parallel sliding correlation detection result sequences are obtained.

[0016] In each detection calculation result sequence, its peak value and corresponding position (Peak Pos) are detected and recorded respectively.

[0017] By comparing the peak values ​​of the three sequences, Search selects the global maximum peak value (Max Peak Value) and records its position (Max Peak Pos) and the corresponding PSS sequence number (NID2).

[0018] At the same location (Max Peak Pos), the correlation values ​​of two other PSS sequences were extracted and treated as background noise.

[0019] Calculate the signal-to-noise ratio (SNR), or the ratio of peak value to noise floor.

[0020] Determine if the ratio exceeds a preset detection threshold: If it exceeds the threshold, the PSS detection is considered reliable, and a valid NID2 and peak position are output, indicating a successful process. If it does not exceed the threshold, the PSS detection is considered unreliable, and synchronization is deemed a failure.

[0021] In the above process, when there are multiple base stations in the vicinity and the frame headers are aligned, multiple PSS sequences may show high peak values ​​at the same location. In this case, taking the peak values ​​of the other two sequences as the "noise floor" will be seriously overestimated, resulting in distorted signal-to-noise ratio calculation, unreliable threshold judgment, and thus causing synchronization detection failure.

[0022] As mentioned above, when there are multiple base stations in the vicinity and the frame headers are aligned, during the PSS coarse synchronization process on the relevant time domain data, the three sets of sequences may have relatively high peak points at the same location, and the conventional threshold judgment method cannot accurately filter out the reasonable cell signal.

[0023] This embodiment proposes a method for initial signal synchronization in 5G base station sniffer mode, involving the function of eliminating inter-site interference during initial synchronization in 5G NR base station sniffer mode, in order to better solve the threshold determination failure problem caused by interference between multiple base stations. Figure 2 As shown, it includes: This invention introduces two artificially constructed PSS sequences X / Y (with low correlation to the three PSS sequences generated by other protocols). The PSS sequences X / Y are generated through an algorithm simulation platform, consisting of two sequences of 127 points with low correlation to the protocol sequences. Sliding correlation detection is performed between the X / Y sequences (NID2 = 0, NID2 = 1, NID2 = 2) and the received data. The sliding correlation process is as follows: Figure 3 As shown, a set of 5 detection results is obtained. The maximum peak value among NID2=1, 2, and 3 is selected, and the peak position (Peak Pos) of that peak is obtained. From the X / Y detection set, the x-sequence peak value and y-sequence peak value corresponding to the peak position (Peak Pos) are extracted.

[0024] In the generation of PSS sequences X / Y, MATLAB simulation software was used to generate two sets of zc sequences that differ significantly from the original PSS root indices and satisfy low correlation. For example, NID2 = 0 / 1 / 2 was calculated conventionally. Using NID2=[3:126], multiple sets of 127-point sequences were generated, and then correlated with the original sequences. The sequences selected were those whose cross-correlation peaks with the three sets were all ≤0.1 or ≤0.08.

[0025] The dynamic threshold is calculated as follows: Dynamic threshold T = (x Peak Value + y Peak Value) / 2 * Max_Par_Ratio (maximum peak-to-average ratio - configurable). Through digital power normalization, the data power, i.e., the dynamic threshold T and the maximum peak value, is scaled to the same standard range.

[0026] The dynamic threshold T is compared with the maximum peak value detected by the PSS sequence. If the value exceeds the threshold T, the detection is considered valid.

[0027] Max_Par_Ratio can be set through management windows such as Web lmt, with the threshold value (maximum peak-to-average ratio) set according to different scenarios. The threshold value is generally configured with the default value. In special cases, a more reasonable threshold can be obtained by analyzing data through MATLAB based on the interference near the current station.

[0028] In sliding correlation detection, a short, known local sequence (PSS sequence) is moved (slid) point by point along a long, received unknown signal (received signal), and their multiplication at each alignment position is calculated. The multiplication values ​​at the alignment positions are then added together to obtain the value at that position. In the sliding correlation process, the generated local sequence and the received data are slid-multiplied and added sequentially to obtain all the results in this process.

[0029] The base station uses five sets of synchronization signals (NID2 = 0 / 1 / 2 and X / Y) to obtain the maximum peak value and location of the air interface data. The peak values ​​(PeakValue) of the X / Y sequences corresponding to the maximum peak location are used as noise to determine whether a threshold has been reached.

[0030] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for initial signal synchronization in 5G base station sniffer mode, characterized in that, include: Acquire the local PSS sequence and the received signal, perform segment cross-correlation detection on the received signal and the local PSS sequence, and filter the maximum peak value from the cross-correlation detection results of the local PSS sequence. The local PSS sequence corresponding to the maximum peak is used as the reference peak, and the peak position of the reference peak is obtained. Construct a detection PSS sequence, perform segment cross-correlation detection on the received signal and the detection PSS sequence, and find the peak position of the reference peak in the cross-correlation detection results of the detection PSS sequence to obtain the peak value of the detection sequence. The initial synchronization of the signal is determined by comparing the peak value of the detected sequence with the reference peak value.

2. The method according to claim 1, characterized in that, The number of detected PSS sequences is one or more, and the correlation between the detected PSS sequences and the local PSS sequences is low.

3. The method according to claim 1, characterized in that, The local PSS sequence is a PSS sequence with NID=0, 1, 2.

4. The method according to claim 1, characterized in that, The segment cross-correlation detection adopts sliding detection, which calculates the correlation values ​​between different segments of the received signal and the PSS sequence. Specifically, it calculates the multiplication value of the alignment position of the current segment and the PSS sequence, and sums all the multiplication values ​​to obtain the correlation value between the current segment position and the PSS sequence.

5. The method according to claim 1, characterized in that, The process of determining the baseline peak value based on the peak value of the detected sequence includes: Calculate the mean of the peak values ​​in the detection sequence, construct the maximum peak-to-average ratio (PAPR), multiply the mean and PAPR to obtain a threshold value, compare the threshold value with the reference peak value, and determine that the initial synchronization of the detection signal is complete when the reference peak value is greater than the threshold value; otherwise, it is not complete.

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