Construction method and detection method of access synchronization sequence and method for accessing base station

Abstract

The invention discloses an access synchronization sequence construction method, a detection method and a base station access method, and the access synchronization sequence construction method comprises the steps: constructing a first initial sequence set based on a plurality of first initial sequences satisfying low correlation, constructing a second initial sequence set based on a plurality of second initial sequences meeting low correlation; the low correlation meeting comprises that the sequence itself meets the low autocorrelation and the sequences meet the low cross correlation; and performing Kronecker product operation on any two initial sequences from the first initial sequence set and the second initial sequence set to obtain a plurality of target sequences, and constructing a set of access synchronization sequences distributed to a user terminal based on the target sequences. The requirement that large-scale users access the network at the same time can be met, and high detection performance and system reliability are guaranteed.

Description

Technical Field

[0001] The present application relates to the field of access synchronization sequence design, and in particular to a method for constructing and detecting an access synchronization sequence and a method for accessing a base station. Background Art

[0002] The access synchronization sequence is a special signal sequence sent to the base station during the random access process of a user terminal (UE) in mobile communications when initiating network access. It is mainly used to achieve uplink timing synchronization and terminal identity identification, and assist the base station in estimating the transmission delay (first path delay) to apply for access resources from the base station.

[0003] There are many types of access synchronization sequences. Taking the Zadoff-Chu (ZC) sequence as an example, the ZC sequence is widely used as an access synchronization sequence in current communication standards.

[0004] Although ZC sequences excel in low-speed scenarios due to their excellent autocorrelation properties, in high-speed environments, the influence of Doppler frequency offset can cause a large number of high sidelobes in the ZC sequence's ambiguity function to interfere with the detection process. To mitigate the impact of high sidelobes on detection, a restricted set is introduced to compensate for Doppler frequency offset. However, while this compensation measure effectively mitigates the impact of Doppler frequency offset on detection accuracy, it also significantly reduces the number of available ZC sequences, making it unable to meet the needs of large-scale user terminal access. Summary of the Invention

[0005] To address the above technical issues, the present application provides a method for constructing an access synchronization sequence, a method for detecting an access synchronization sequence, a method for accessing a base station, a computer program product, an electronic device, and a computer-readable storage medium. The technical solutions are as follows:

[0006] According to a first aspect of the present application, a method for constructing an access synchronization sequence is provided, which is applied to a base station. The method includes:

[0007] A first initial sequence set is constructed based on a plurality of first initial sequences that satisfy low correlation, and a second initial sequence set is constructed based on a plurality of second initial sequences that satisfy low correlation; wherein satisfying low correlation includes: the sequences themselves satisfying low autocorrelation, and the sequences satisfying low mutual correlation;

[0008] A Kronecker product operation is performed on any two initial sequences from the first initial sequence set and the second initial sequence set to obtain several target sequences, and a set of access synchronization sequences for distribution to user terminals is constructed based on the target sequences.

[0009] According to a second aspect of the present application, a method for detecting an access synchronization sequence based on the method described in the first aspect is provided, and the method is applied to a base station, wherein the first initial sequence is used as an outer sequence when performing the Kronecker product operation, and the second initial sequence is used as an inner sequence when performing the Kronecker product operation; the method comprising:

[0010] receiving an access synchronization sequence to be detected sent by a user terminal, where the access synchronization sequence to be detected is constructed based on the method described in the first aspect and distributed to the user terminal;

[0011] performing correlation operations on the access synchronization sequence to be detected and each inner sequence in the second initial sequence set to obtain correlation operation results;

[0012] Performing a dot product operation on the correlation operation result and each outer sequence in the first initial sequence set to obtain a dot product operation result;

[0013] Based on the dot product result, the ID of the user terminal and the first path delay between the user terminal and the base station are detected, so as to enable the user terminal to access based on the ID and the first path delay.

[0014] According to a third aspect of the present application, a method for accessing a base station is provided, which is applied to a user terminal, and the method includes:

[0015] receiving an indication message sent by a base station, where the indication message is used to instruct the user terminal to select an access synchronization sequence;

[0016] Based on the indication message, determine a target access synchronization sequence from the set of access synchronization sequences constructed by the method of the first aspect;

[0017] The target access synchronization sequence is sent to the base station, so as to access the base station based on the target access synchronization sequence.

[0018] According to a fourth aspect of the present application, a computer program product is provided, which includes a computer program, and when the computer program is executed by a processor, it implements the method described in any one of the first to third aspects.

[0019] According to a fifth aspect of the present application, a base station is provided, comprising:

[0020] processor;

[0021] a memory for storing processor-executable instructions;

[0022] The processor is configured to implement the method as described in the first aspect or the second aspect.

[0023] According to a sixth aspect of the present application, a terminal device is provided, comprising:

[0024] processor;

[0025] a memory for storing processor-executable instructions;

[0026] The processor is configured to implement the method described in the third aspect.

[0027] According to the seventh aspect of the present application, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps in the method described in any one of the first to third aspects are implemented.

[0028] The technical solution provided in the present application constructs a first initial sequence set based on several first initial sequences that satisfy low correlation, and constructs a second initial sequence set based on several second initial sequences that satisfy low correlation. Satisfying low correlation includes: the sequence itself satisfies low autocorrelation, and the sequences satisfy low mutual correlation. A Kronecker product operation is performed on any two initial sequences from the first initial sequence set and the second initial sequence set, respectively, to obtain several target sequences, and based on the target sequences, a set of access synchronization sequences for distribution to user terminals is constructed.

[0029] Due to the properties of the Kronecker product, the sequences in the above-mentioned set of access synchronization sequences not only inherit the low correlation characteristics of the sequences in the first initial sequence set and the second initial sequence set, but also generate a large number of new low-correlation sequences (target sequences) through Kronecker product expansion. These newly generated target sequences can serve as access synchronization sequences to meet the needs of large-scale users accessing the network simultaneously, effectively solving the problem of insufficient capacity of traditional sequences.

[0030] Compared to traditional ZC sequences, the sequences in this access synchronization sequence set exhibit significant advantages in Doppler resistance. Due to the structural characteristics of the Kronecker product, the sequences in this access synchronization sequence set maintain low correlation even in Doppler frequency offset environments, making them less susceptible to the Doppler effect in high-speed mobile scenarios. This characteristic makes the sequences in this access synchronization sequence set valuable for high-speed communication scenarios (such as high-speed rail communications, vehicle networks, and drone communications). The low correlation of these sequences reduces the probability of false alarms, thereby ensuring high detection performance and system reliability.

[0031] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following briefly introduces the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are only some embodiments recorded in this application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0033] Figure 1 This is a schematic diagram of an application scenario of an embodiment of the present application;

[0034] Figure 2 is a schematic diagram of another application scenario of an embodiment of the present application;

[0035] Figure 3 is a schematic diagram of another application scenario of an embodiment of the present application;

[0036] Figure 4 This is a flowchart of a method for constructing an access synchronization sequence according to an embodiment of the present application;

[0037] Figure 5 This is a schematic diagram of an access synchronization sequence construction scenario according to an embodiment of the present application;

[0038] Figure 6 This is a flowchart of a method for detecting an access synchronization sequence according to an embodiment of the present application;

[0039] Figure 7 Schematic diagram of a sequence detection scenario in related art;

[0040] Figure 8 This is a schematic diagram of an access synchronization sequence detection scenario according to an embodiment of the present application;

[0041] Figure 9 This is a flowchart of a method for accessing a base station according to an embodiment of the present application;

[0042] Figure 10 This is a schematic diagram of a scenario in which an access synchronization sequence is sent according to an embodiment of the present application;

[0043] Figure 11 This is a schematic diagram illustrating experimental data of an embodiment of the present application;

[0044] Figure 12 This is a schematic diagram illustrating experimental data of another embodiment of the present application;

[0045] Figure 13 This is a schematic structural diagram of a base station according to an embodiment of the present application;

[0046] Figure 14 It is a structural diagram of a terminal device according to an embodiment of the present application. DETAILED DESCRIPTION

[0047] In order to enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be described in detail below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art should fall within the scope of protection of this application.

[0048] like Figure 1 As shown in the 2016 International Mobile Telecommunications (IMT) 2030 report, with the rapid growth of the number of smart terminal devices, future large-scale communication scenarios will face the need to support ultra-high density and large-scale user access. This development trend not only means a surge in the number of user terminal devices connected to base stations, but also is accompanied by increasingly diversified communication needs. At the same time, communication systems continue to expand to higher carrier frequencies and a wider range of application scenarios. Figure 2 As shown, especially in high-speed transmission environments (such as high-speed rail scenarios), the Doppler frequency offset effect in the channel also shows a significant increasing trend, which brings unprecedented challenges to user access.

[0049] The access synchronization sequence is a special signal sequence sent to the base station during the random access process of a user terminal (UE) in mobile communications when initiating network access. It is mainly used to achieve uplink timing synchronization and terminal identity identification, and assist the base station in estimating the transmission delay (first path delay) to apply for access resources from the base station.

[0050] There are many types of access synchronization sequences. Taking the Zadoff-Chu (ZC) sequence as an example, the ZC sequence is widely used as an access synchronization sequence in current communication standards.

[0051] like Figure 3 As shown in the figure, although the ZC sequence performs well in low-speed scenarios due to its good autocorrelation properties, in high-speed environments, the influence of Doppler frequency offset can cause a large number of high sidelobes in the ZC sequence's ambiguity function to interfere with the detection process. To prevent the impact of high sidelobes on detection, it is necessary to introduce a restricted set to compensate for Doppler frequency offset. However, while this compensation measure can effectively alleviate the impact of Doppler frequency offset on detection accuracy, it also significantly reduces the number of available ZC sequences, making it unable to meet the needs of large-scale user terminal access, especially in high-speed and high-density access scenarios.

[0052] It can be understood that Doppler shift is a physical phenomenon in which the received frequency shifts relative to the transmitted frequency when the wave source and the observer are in relative motion. Its core principle is that when the two are close to each other, the wavelength is compressed and the frequency increases; when they are farther away, the wavelength is stretched and the frequency decreases. In mobile communication scenarios, the Doppler shift effect is the carrier frequency offset phenomenon caused by the relative motion of the transmitter and receiver in wireless communication channels. Its impact is exacerbated as the speed and carrier frequency increase (such as in 5G millimeter wave scenarios).

[0053] Some high-capacity sequence design schemes based on ZC sequences have been proposed in the related art. However, these designs can only withstand small Doppler offsets. When encountering large Doppler offsets in high-speed scenarios (such as on high-speed trains, where the system is moving at high speed relative to the base station), the sequence performance will still be significantly affected. Therefore, some design schemes have been proposed in the related art to address sequence Doppler sensitivity. However, these sequence design methods in the related art focus solely on the design of the sequence itself, ignoring the structure of the sequence and the complexity of the base station's detection algorithm for the sequence. The computational complexity of the detection algorithm required for these sequences is generally proportional to the number of connected users. This means that in high-density user access scenarios, the base station's computational overhead will increase significantly, leading to a significant increase in system resource consumption and operating costs. To meet this challenge, future communication systems urgently need a structured sequence design and a corresponding low-complexity detection algorithm. This algorithm should not only accurately detect user terminal (device) IDs and estimate first-path delay, but also have extremely low computational complexity, thereby preventing a sharp increase in operating costs.

[0054] Therefore, for the complex application scenarios of high speed and high connection density in the 6G era, it is urgent to design a new, high-capacity, Doppler-resistant access synchronization sequence and develop a low-complexity detection algorithm to match it. This will be the key to the efficient and stable operation of future communication systems and one of the important directions for the development of 6G technology.

[0055] In response to the above problems, this application provides a method for constructing an access synchronization sequence, which is applied to base stations and can meet the needs of large-scale users accessing the network at the same time. It effectively solves the problem of insufficient capacity of traditional sequences and has important application value in high-speed communication scenarios (such as high-speed rail communication, vehicle networking, drone communication, etc.). It reduces the probability of false alarm detection, thereby ensuring high detection performance and system reliability. Figure 4 As shown, the method includes the following steps:

[0056] S401: Construct a first initial sequence set based on a plurality of first initial sequences that satisfy low correlation, and construct a second initial sequence set based on a plurality of second initial sequences that satisfy low correlation.

[0057] The satisfying of low correlation includes: the sequence itself satisfying low autocorrelation, and the sequences satisfying low mutual correlation.

[0058] S402: Perform a Kronecker product operation on any two initial sequences from the first initial sequence set and the second initial sequence set to obtain several target sequences, and construct a set of access synchronization sequences for distribution to user terminals based on the target sequences.

[0059] The technical solution provided by the embodiments of the present application constructs a first initial sequence set based on several first initial sequences that satisfy low correlation, and constructs a second initial sequence set based on several second initial sequences that satisfy low correlation. Satisfying low correlation includes: the sequence itself satisfies low autocorrelation, and the sequences satisfy low mutual correlation. A Kronecker product operation is performed on any two initial sequences from the first initial sequence set and the second initial sequence set, respectively, to obtain several target sequences, and based on the target sequences, a set of access synchronization sequences for distribution to user terminals is constructed.

[0060] Due to the properties of the Kronecker product, the sequences in the above-mentioned set of access synchronization sequences not only inherit the low correlation characteristics of the sequences in the first initial sequence set and the second initial sequence set, but also generate a large number of new low-correlation sequences (target sequences) through Kronecker product expansion. These newly generated target sequences can serve as access synchronization sequences to meet the needs of large-scale users accessing the network simultaneously, effectively solving the problem of insufficient capacity of traditional sequences.

[0061] Compared to traditional ZC sequences, the sequences in this access synchronization sequence set exhibit significant advantages in Doppler resistance. Due to the structural characteristics of the Kronecker product, the sequences in this access synchronization sequence set maintain low correlation even in Doppler frequency offset environments, making them less susceptible to the Doppler effect in high-speed mobile scenarios. This characteristic makes the sequences in this access synchronization sequence set valuable for high-speed communication scenarios (such as high-speed rail communications, vehicle networks, and drone communications). The low correlation of these sequences reduces the probability of false alarms, thereby ensuring high detection performance and system reliability.

[0062] It can be understood that the above-mentioned low correlation includes: the sequence itself meets the preset low autocorrelation standard, and the sequences meet the preset low mutual correlation standard.

[0063] As an example, the low correlation mentioned above may mean that the correlation values ​​between sequences and the correlation values ​​within a sequence are both less than a set value. It is understood that when a correlation analysis is performed between any two sequences in the same sequence set, a value corresponding to the correlation can be obtained.

[0064] The above-mentioned set value can be determined in various ways. As an example, one determination method may include: setting the value based on 0.1 times the total energy of the sequence; as another example, the total sequence energy of any sequence can be determined by performing a correlation analysis between the sequence and itself.

[0065] The sequence types of the first initial sequence and the second initial sequence can be implemented in a variety of specific ways. As an example, the sequence types of the first initial sequence include a Zadoff-Chu (ZC) sequence, a maximum linear shift register (m) sequence, and a cubic phase polynomial (Alltop) sequence; the sequence types of the second initial sequence include a Zadoff-Chu sequence, a maximum linear shift register sequence, and a cubic phase polynomial (Alltop) sequence. It can be understood that the sequence type of the first initial sequence can be one of the Zadoff-Chu (ZC) sequence, the maximum linear shift register (m) sequence, and the cubic phase polynomial (Alltop) sequence, or other sequence types, without limitation; the sequence type of the second initial sequence can be one of the Zadoff-Chu sequence, the maximum linear shift register sequence, and the cubic phase polynomial (Alltop) sequence, or other sequence types, without limitation.

[0066] As another example, the sequence types of the first initial sequence and the second initial sequence can be different. The constructed first initial sequence set and second initial sequence set can combine the advantages of multiple types of sequences, complement each other's advantages while avoiding their respective shortcomings, thereby ensuring better performance. For example, under the premise of ensuring sequence capacity expansion, the first initial sequence uses the above-mentioned ZC sequence, and the second initial sequence uses the above-mentioned m sequence. This can ensure that the new sequence obtained after the Kronecker product operation between the two has stronger anti-Doppler frequency shift performance.

[0067] As another example, while ensuring that sequence capacity is expanded, the first and second initial sequences may be of the same sequence type. For example, both the first and second initial sequences may be ZC sequences. Therefore, there is no specific limitation on whether the first and second initial sequences are of the same sequence type.

[0068] It is worth noting that the above description of the specific implementation of the sequence types of the first initial sequence and the second initial sequence is only an exemplary display. In actual application, other specific implementations are not excluded and are not specifically limited to this.

[0069] As an example, if the first initial sequence is a ZC sequence, the first initial sequence set may include several ZC sequences of the same length but different root indices. Similarly, if the second initial sequence is a ZC sequence, the second initial sequence set may also include several ZC sequences of the same length but different root indices. As another example, if the first initial sequence is an Alltop sequence, the first initial sequence set may include several Alltop sequences of the same length but different parameter settings. Similarly, if the second initial sequence is an Alltop sequence, the second initial sequence set may also include several Alltop sequences of the same length but different parameter settings.

[0070] As can be understood, the ZC sequence is a complex exponential sequence, proposed by Zadoff and Chu. Each point in the complex plane lies on the unit circle, thus exhibiting constant amplitude (constant envelope). In communication systems, ZC sequences generate a large number of orthogonal or quasi-orthogonal sequences through different "root indices" (root exponents) and cyclic shifts. They exhibit zero autocorrelation, low cross-correlation, Fourier transform invariance, and strong adaptability to different scenarios. The m-sequence is generated by a linear feedback shift register (LFSR), which uses a specific feedback logic (primitive polynomial) to generate a periodic binary sequence. It is a typical pseudo-random sequence with sharp autocorrelation, random characteristics (balance and run-length distribution), and shift additivity. The Alltop sequence is a cubic phase variant of the ZC sequence. It is an extension of the ZC sequence that replaces the quadratic phase term with a cubic phase term, significantly improving frequency offset resistance. However, it has higher computational complexity. It exhibits high frequency offset tolerance and two-dimensional time-frequency orthogonality.

[0071] The Kronecker product operation can be performed on any two initial sequences from the first initial sequence set and the second initial sequence set in a variety of ways. As an example, the first initial sequence from the first initial sequence set can be used as the outer sequence of the Kronecker product, and the second initial sequence from the second initial sequence set can be used as the inner sequence of the Kronecker product, and the Kronecker product operation can be performed between the first initial sequence and the second initial sequence. Based on the properties of the Kronecker product, the target sequence obtained after the Kronecker product operation can be divided into an outer sequence (from the first initial sequence set) and an inner sequence (from the second initial sequence set), so that when the base station detects the access synchronization sequence, it can perform step-by-step detection according to the inner and outer sequences, thereby reducing the computational complexity of the detection. It is worth noting that the above introduction to the specific implementation of the Kronecker product operation is only an exemplary display. In actual applications, other specific implementations are not excluded, and this is not specifically limited.

[0072] To further expand the capacity of the access synchronization sequence set to meet the needs of a larger number of user terminals accessing the base station, as an example, several target sequences obtained by performing a Kronecker product operation on any two initial sequences from the first initial sequence set and the second initial sequence set can be cyclically shifted to obtain several cyclically shifted sequences corresponding to the target sequences. Based on the target sequences and the cyclically shifted sequences corresponding to the target sequences, a set of access synchronization sequences for distribution to user terminals can be constructed. Further cyclic shifting operations can be performed on the target sequences obtained by the Kronecker product operation to obtain more new sequences.

[0073] There are many ways to perform cyclic shift on the target sequence. As an example, before performing the cyclic shift, a cyclic shift parameter may be determined first, and then the cyclic shift operation is performed on the target sequence based on the cyclic shift parameter.

[0074] The cyclic shift parameter can be determined in various ways. As an example, a cyclic shift step size can be first determined, and then any multiple of the cyclic shift step size can be determined as the cyclic shift parameter. As another example, a preset multiple of the cyclic shift step size can be determined as the cyclic shift parameter. As another example, the cyclic shift step size does not need to be determined, and a preset value can be directly used as the cyclic shift parameter. Therefore, there is no specific limitation on the method for determining the cyclic shift parameter.

[0075] As an example, a Kronecker product operation is performed on any two initial sequences from the first initial sequence set and the second initial sequence set, that is, any sequence is taken from the first initial sequence set and any sequence is taken from the second initial sequence set, and the two sequences are subjected to a Kronecker product operation; all sequences in the first initial sequence set and the second initial sequence set are traversed respectively, and the above-mentioned Kronecker product operation is performed on each of them.

[0076] The following combination Figure 5 , an exemplary description is given of a specific access synchronization sequence construction scenario in an embodiment of the present application:

[0077] As an example, for the convenience of description, let the first initial sequence set be Ω1, the second initial sequence set be Ω2, and the access synchronization sequence set be Ω3. Take different sequences in Ω1 and Ω2 to make Kronecker products, and add the results of the Kronecker products to the new sequence set Ω3 (i.e., the access synchronization sequence set). When any sequence in Ω1 is made into a Kronecker product with any sequence in Ω2, the sequence in Ω1 is the outer sequence of the Kronecker product, and the sequence in Ω2 is the inner sequence of the Kronecker product. Figure 5 As shown, let one of the sequences in Ω1 be s1={s1[0],s1[1],…,s1[L o -1]}, let one of the sequences in Ω2 be s2={s2[0],s2[1],…,s2[L i -1]}, where L o With L i Represent the length of sequences s1 and s2 respectively. The Kronecker product of s1 and s2 can be regarded as the product of L o The long sequence consists of inner sequence blocks, where the i-th sequence block can be expressed as the product of s1[i] and s2.

[0078] As another example, all new sequences obtained by performing Kronecker product operations on each sequence in Ω1 and each sequence in Ω2 are subjected to N CS If the sequence obtained after the cyclic shift is not in the set Ω3, it is added to the set Ω3; if it is already in Ω3, it is not added to the set Ω3 again. At this time, the sequences in Ω3 include the sequence obtained by taking the Kronecker product of any sequence in Ω1 and any sequence in Ω2 (the above-mentioned target sequence), as well as all target sequences cyclically shifted by N. CS The sequences obtained after any multiple of .

[0079] In this embodiment, the Ω3 design offers unique advantages from the perspective of sequence structure and detection algorithm. Due to the properties of the Kronecker product, the correlation results of the Ω3 sequence can be decomposed into a combination of the correlation results of the inner sequence (from Ω2) and the outer sequence (from Ω1). This structural feature enables separate correlation analysis of the inner and outer sequences during access synchronization sequence detection, and then effectively integrating the results to obtain the correlation results of the entire sequence. This step-by-step detection method not only simplifies the calculation process but also significantly reduces the complexity of the detection algorithm, making it particularly suitable for resource-constrained communication devices or scenarios requiring real-time processing.

[0080] Furthermore, the Ω3 design is highly flexible and scalable. By selecting different combinations of inner and outer sequences, a sequence set can be generated to suit different scenarios. For example, in scenarios requiring higher Doppler immunity, an outer sequence with stronger Doppler immunity can be selected. In scenarios requiring greater capacity, the size of the sequence set can be expanded by increasing the diversity of the inner or outer sequences.

[0081] Considering that in the related art, the detection algorithm of the base station for the access synchronization sequence sent by the user terminal is: performing a full-sequence correlation operation on the received access synchronization sequence and all preset access synchronization sequences (i.e., local full sequence) stored locally in the base station, this method has a large amount of calculation, especially when the sequence length is long or the number of users is large, it will bring huge pressure to the computing resources of the base station.

[0082] In response to the above problems, based on the construction method of the access synchronization sequence described in any of the above embodiments, this application provides a detection method for an access synchronization sequence, which is applied to a base station; the above first initial sequence is used as an outer sequence when performing the above Kronecker product operation, and the above second initial sequence is used as an inner sequence when performing the above Kronecker product operation; it is possible to implement step-by-step detection of the access synchronization sequence constructed by the method described in any of the above embodiments, significantly reducing the computational complexity of the detection process, reducing the computational burden on the base station end, and effectively controlling operating costs. Figure 6 As shown, the method includes the following steps:

[0083] S601: Receive an access synchronization sequence to be detected from a user terminal.

[0084] The access synchronization sequence to be detected is constructed based on the access synchronization sequence construction method described in any one of the above embodiments and then distributed to the user terminal.

[0085] S602: Perform correlation operations on the access synchronization sequence to be detected and each inner sequence in the second initial sequence set to obtain correlation operation results.

[0086] S603: Perform a dot product operation on the correlation operation result and each outer sequence in the first initial sequence set to obtain a dot product operation result.

[0087] S604: Detect the ID of the user terminal and the first path delay between the user terminal and the base station based on the dot product operation result, so as to enable the user terminal to access based on the ID and the first path delay.

[0088] The technical solution provided by the embodiment of the present application is different from the traditional detection solution of detecting full sequence correlation. It adopts a step-by-step detection algorithm. First, the base station performs a correlation operation on the received access synchronization sequence to be detected with the inner sequence to obtain an inner correlation result (correlation operation result); then, this result is multiplied point by point with the outer sequence, thereby obtaining a result equivalent to performing a two-dimensional correlation operation on the full sequence in the set of access synchronization sequences pre-constructed in the base station and the received access synchronization sequence to be detected (that is, the result obtained by the step-by-step detection of this embodiment can replace the traditional full sequence detection result). Based on this equivalent result, the identity (ID) of the user terminal (device) and the first path delay between the user terminal and the base station are accurately detected. By cleverly utilizing the structural characteristics of the sequence obtained by the Kronecker product, the computational complexity of the detection process is significantly reduced, the computational burden on the base station end is reduced, and the operating cost is effectively controlled.

[0089] It is understandable that due to the influence of the channel, there is a difference between the access synchronization sequence sent by the user terminal side and the access synchronization sequence actually received by the base station side. The embodiment of the present application defines the access synchronization sequence actually received by the base station as the above-mentioned "access synchronization sequence to be detected".

[0090] The above-mentioned dot product operation result can be obtained in various ways. As an example, the above-mentioned correlation operation result and the above-mentioned dot product operation result can both be in matrix form, wherein the correlation operation result can correspond to a first matrix, and the dot product operation result can correspond to a second matrix. Each column of the first matrix corresponding to the above-mentioned correlation operation result can be dot-producted with each outer sequence in the above-mentioned first initial sequence set, and a fast Fourier transform can be performed on the columns of the first matrix to obtain a second matrix corresponding to the above-mentioned dot product operation result. The correlation operation result and the dot product operation result are both organized in matrix form for convenient calculation. At the same time, performing a fast Fourier transform when performing the dot product operation with the outer sequence can compensate for Doppler frequency offset.

[0091] Considering that the Doppler frequency shift is compensated only when performing the point product operation on the outer sequence in the above distribution detection, it may cause the main peak energy loss due to incomplete Doppler compensation, resulting in inaccurate detection of the user terminal's identity (ID) and the first path delay between the user terminal and the base station.

[0092] To address this issue, the ID of the user terminal and the first path delay between the user terminal and the base station can be detected in a variety of ways. As an example, based on the second matrix corresponding to the result of the above-mentioned point multiplication operation, a preset number of access synchronization sequences with the highest correlation with the access synchronization sequence to be detected sent by the user terminal can be determined from the above-mentioned set of access synchronization sequences; these preset number of access synchronization sequences are correlated with the access synchronization sequence to be detected, and fast Fourier transforms are performed on each of them to obtain a preset number of correlation vectors; if a target correlation vector exists among the preset number of correlation vectors, and the modulus of the target correlation vector is greater than a preset modulus threshold, the identity (ID) of the user terminal and the first path delay between the user terminal and the base station are detected based on the target correlation vector; wherein the modulus of the target correlation vector is the maximum value among the above-mentioned preset number of correlation vectors. It is worth noting that the above-mentioned introduction to the method of detecting the ID of the user terminal and the first path delay between the user terminal and the base station is only an exemplary display. In actual applications, other detection methods are not excluded and are not specifically limited to this.

[0093] In this embodiment, after performing corresponding operations on the inner sequence and the outer sequence, several sequences that are most relevant to the access synchronization sequence to be detected are extracted, and FFT (Fast Fourier Transform) is further performed on all of these sequences to further perform Doppler compensation and reduce the main peak energy loss caused by incomplete Doppler compensation (previously, compensation was only performed on the outer sequence instead of the entire sequence).

[0094] The following combination Figure 7 、 Figure 8 , a specific access synchronization sequence detection scenario of an embodiment of the present application is exemplarily described:

[0095] After receiving the access synchronization sequence to be detected sent by the user terminal, the base station needs to detect the access synchronization sequence to be detected to determine the user terminal ID and the first path delay.

[0096] The traditional detection algorithm in related technology can be found in Figure 7As shown, the conventional detection process in the related art includes: After receiving the access synchronization sequence, the base station first passes it through a low-pass filter and a down-conversion module, and then removes the cyclic prefix (CP) part. In order to avoid the influence of Doppler frequency offset on the detection, N D Doppler compensation of the point, and get N after different Doppler compensation D A sequence is taken, and an N-point Fast Fourier Transform (FFT) is performed on each of them, and the sequence is converted to the frequency domain. The sequence is extracted from the corresponding subcarrier, and the frequency domain dot product is performed on the extracted sequence with each sequence in the sequence set. The frequency domain dot product result is then transformed to the time domain through the Inverse Discrete Fourier Transform (IDFT) or the Inverse Fast Fourier Transform (IFFT) to obtain the time domain correlation result. The time domain correlation result is used to perform normalized threshold detection to obtain the user ID (i.e., user terminal device ID) and the first path delay. The traditional detection algorithm in the above-mentioned related technology requires the access synchronization sequence sent by the terminal received by the base station to perform full sequence correlation detection with all sequences in the local sequence set of the base station. The complexity is extremely high, especially in large-scale access scenarios, where the number of users further increases and the computational burden of the base station is further increased.

[0097] In order to alleviate the above problems, the detection method of the access synchronization sequence proposed in the embodiment of the present application uses the result of the correlation operation between the inner sequence and the received access synchronization sequence to be detected to multiply the result with the outer sequence point by point, so as to replace the correlation result between the full sequence and the received access synchronization sequence to be detected. Figure 8 As shown in FIG, the process specifically includes: the base station receives the access synchronization sequence to be detected sent by the client (user terminal), passes it through a low-pass filter and a down-conversion module, and then removes the CP part. The base station performs frequency domain dot multiplication on each sequence in the above Ω2 and the access synchronization sequence to be detected, and then transforms the frequency domain dot multiplication result to the time domain through IDFT or FFT to obtain the time domain correlation result, and organizes the time domain correlation result into a shape of L o ×L i The base station multiplies each sequence in Ω1 and the sequences obtained by cyclic shifting the sequences with each column of the first matrix Γ1 in turn, and performs fast Fourier transform on each column to compensate for Doppler frequency offset. The result of the operation is recorded as the second matrix Γ2. The N with the largest modulus length in the second matrix Γ2 m (N m >1) values ​​are selected, and their corresponding N m Group sequence (including sequence in Ω2 and sequence in Ω1) and its corresponding Nm The cyclic shift parameters are recorded. m N is obtained by taking Kronecker product of group sequence m Sequences are correlated with the access synchronization sequence to be detected, and FFT is performed to compensate for Doppler frequency deviation. The result of the operation is N m related vectors, denoted as v1, v2, ..., v1, v2, ..., The maximum value of the middle modulus is compared with the predefined threshold (i.e. the above-mentioned preset modulus threshold) in turn. i If the maximum value is greater than the threshold, it is considered that a client device is accessing the base station, and then v i The corresponding sequence group, cyclic shift parameter and maximum peak value determine the client device ID (user terminal device ID) and the first path delay.

[0098] The advantage of the step-by-step detection in this embodiment is that the originally complex high-dimensional full sequence correlation operation is decomposed into two low-dimensional operation steps, namely the correlation operation of the inner sequence and the point-by-point multiplication operation of the outer sequence. Since the lengths of the inner sequence and the outer sequence are usually much smaller than the length of the full sequence (i.e., the above-mentioned target sequence), this decomposition significantly reduces the amount of calculation. In addition, this detection method can still ensure high detection performance while reducing the computational complexity. Therefore, the detection method of this embodiment can not only accurately identify user access signals, but also maintain a low false alarm probability and missed detection probability in a Doppler frequency deviation environment, thereby ensuring the reliability and stability of the system.

[0099] Based on the method for constructing the access synchronization sequence described in any of the above embodiments, the present application also provides a method for accessing a base station, which is applied to a user terminal. Figure 9 As shown, the method includes the following steps:

[0100] S901: Receive an indication message sent by a base station.

[0101] The indication message is used to instruct the user terminal to select an access synchronization sequence.

[0102] S902: Based on the indication message, determine a target access synchronization sequence in the constructed set of access synchronization sequences.

[0103] S903: Send the target access synchronization sequence to the base station, so as to access the base station based on the target access synchronization sequence.

[0104] The above-mentioned set of access synchronization sequences is constructed based on the method for constructing the access synchronization sequence described in any one of the above embodiments.

[0105] The user terminal may determine the target access synchronization sequence in a variety of ways. For example, the user terminal may pre-store the first initial sequence set and the second initial sequence set described in the method for constructing the access synchronization sequence described in any of the above embodiments. The indication message sent by the base station may include at least a first selection indication for the first target sequence in the first initial sequence set and a second selection indication for the second target sequence in the second initial sequence set. The user terminal may determine the first target sequence in the first initial sequence set pre-stored by the user terminal based on the first selection indication, and determine the second target sequence in the second initial sequence set pre-stored by the user terminal based on the second selection indication. The user terminal performs a Kronecker product operation on the determined first target sequence and the determined second target sequence to obtain a Kronecker product result, and determines the target access synchronization sequence in the access synchronization sequence set based on the Kronecker product result. The user terminal pre-stores two initial sequence sets. The base station only needs to send a selection indication for the two initial sequences. The user terminal may select the corresponding two sequences according to the indication and perform a Kronecker product operation again to obtain the target access synchronization sequence.

[0106] As another example, another manner in which the user terminal determines the target access synchronization sequence may include: an indication message sent by the base station to the user terminal may directly include an indication of the target sequence in the set of access synchronization sequences, and the user terminal may directly determine the target access synchronization sequence based on the indication. As another example, the user terminal may also directly pre-store the set of access synchronization sequences, and the base station may not directly send an indication of the target sequence to the user terminal, but may only send an indication to search for a sequence in the set of access synchronization sequences, and the user terminal may search for a corresponding sequence in the set of access synchronization sequences based on the selection indication, and use it as the target access synchronization sequence.

[0107] It is worth noting that the above description of the method for the user terminal to determine the target access synchronization sequence is only an example. In actual applications, other determination methods are not excluded and are not specifically limited thereto.

[0108] As another example, the indication message sent by the base station to the user terminal may further include the cyclic shift parameter. The user terminal may perform a cyclic shift operation on the Kronecker product result obtained by performing a Kronecker product operation on the first target sequence and the second target sequence based on the cyclic shift parameter to obtain the cyclically shifted Kronecker product result, and determine the target access synchronization sequence in the set of access synchronization sequences based on the cyclically shifted Kronecker product result. If the base station side performs a cyclic shift operation on the Kronecker product result to expand the sequence set capacity, the user terminal side may also receive the cyclic shift parameter and perform a corresponding cyclic shift operation on the Kronecker product result.

[0109] The following combination Figure 10 , an exemplary introduction is given to a specific scenario of a user terminal accessing a base station in an embodiment of the present application:

[0110] After the base station constructs the access synchronization sequence set based on the first initial sequence set and the second initial sequence set, the base station may send the above-mentioned indication message to the user terminal to instruct the user terminal to determine its exclusive access synchronization sequence. The indication message sent by the base station may include a first selection indication of the first target sequence in Ω1, a second selection indication of the second target sequence in Ω2, and a cyclic shift parameter N v , where N v is the cyclic shift step size N CS The first selection indication is related to the sequence type in Ω1 and can indicate information about a specific sequence in Ω1, including but not limited to the root index of the ZC sequence and the coefficient values ​​of each order of the Alltop sequence. The second selection indication is related to the sequence type in Ω2 and can indicate information about a specific sequence in Ω2, including but not limited to the root index of the ZC sequence and the coefficient values ​​of each order of the Alltop sequence.

[0111] The user terminal determines the target access synchronization sequence corresponding to Ω3 according to the above indication message. Specifically, the client (user terminal) determines the outer sequence and the inner sequence of the Kronecker product according to the first selection indication and the second selection indication, and selects the result of the Kronecker product of the inner sequence and the outer sequence and performs a cyclic shift N. v The obtained sequence corresponds to the target access synchronization sequence in Ω3, which is used as the access synchronization sequence exclusive to the client.

[0112] After completing the above preparations, when the user terminal needs to access the base station, the user sends its exclusive access synchronization sequence (the above target access synchronization sequence, that is, the above access synchronization sequence to be detected) to the base station through the terminal, see Figure 10The specific transmission process of the user terminal may include: assuming the length of the access preamble sequence (i.e., access synchronization sequence) is L, first performing an L-point discrete Fourier transform (DFT) on the access preamble sequence to transform it into the frequency domain, then performing subcarrier mapping, placing the L-point frequency domain results on L subcarriers, adding guard subcarriers (GS), and setting the remaining subcarriers to zero, that is, adding a zero padding region (ZP). Assuming there are N subcarriers in total, performing an N-point inverse fast Fourier transform (IFFT) on all subcarriers to transform them into the time domain, repeating the time domain sequence as needed, adding a cyclic prefix (CP) to combat multipath delay fading, and then sending the access preamble sequence.

[0113] The following is a simulation verification of the access synchronization sequence construction method and the access synchronization sequence detection method described in any of the above embodiments:

[0114] Consider an OFDM system with 2048 subcarriers, with one antenna per user end and eight antennas per base station. The channel model uses the standard TDL-B (Tap Delay Line-B) channel model. In the simulation, the benchmark is the traditional ZC sequence set with a sequence length of 839 in the related art. In this embodiment, Ω1 is selected as an m-sequence set with a sequence length of 15, Ω2 is selected as a ZC sequence set with a sequence length of 59, and all access synchronization sequences in the constructed Ω3 have a length of 885. The Doppler frequency deviation caused by user speed is considered to be between ±4 subcarriers. See Table 1:

[0115] Table 1

[0116]

[0117]

[0118] Table 1 shows a comparison of the number of multiplications required by the detection algorithm of the embodiment of the present application and the traditional detection algorithm in the related art. The detection algorithm of the embodiment of the present application targets a Kronecker product sequence with a length of 885, while the traditional detection algorithm in the related art targets a traditional ZC sequence with a length of 839. It can be seen that when the sequence set size is small, the number of multiplications required by both detection algorithms is not large. The detection algorithm of the embodiment of the present application requires about 10 5 The traditional detection algorithm of related technology requires about 10 6When the sequence set increases in size, the number of multiplications of the traditional detection algorithm of the related technology increases significantly, rising to 10 8 On the contrary, the detection algorithm of the embodiment of the present application can effectively control the increase in the number of multiplications and maintain a low computational complexity due to its unique inner and outer layer results.

[0119] Figure 11 The figure shows the detection curves of the traditional ZC sequence in the related art under different signal-to-noise ratios without Doppler frequency deviation. The horizontal axis is the false alarm probability, the vertical axis is the missed detection probability, and the lines of different colors represent different signal-to-noise ratios. It can be seen that when the signal-to-noise ratio is less than -26.4dB, the traditional ZC sequence in the related art cannot detect the signal when the missed detection probability is less than 10. -2 In the case of -3 That is to say, when the probability of missed detection is less than 10 -2 In the case of -3 The critical signal-to-noise ratio threshold is -26.4dB.

[0120] and Figure 12 The detection curves of the access synchronization sequence of the embodiment of the present application under different signal-to-noise ratios are shown in the case of Doppler frequency deviation. The horizontal axis is the false alarm probability, the vertical axis is the missed detection probability, and the lines of different colors represent different signal-to-noise ratios. It can be seen that when the signal-to-noise ratio is less than -25.2dB, the access synchronization sequence of the embodiment of the present application cannot be detected when the missed detection probability is less than 10. -2 In the case of -3 That is to say, when the probability of missed detection is less than 10 -2 In the case of -3 The critical signal-to-noise ratio threshold is -25.2dB. Figure 11 and Figure 12 By comparison, the access synchronization sequence of the embodiment of the present application, when subjected to Doppler frequency shift, has a threshold value only 1.2 dB higher than the conventional ZC sequence in the related art when it does not experience Doppler frequency shift. This shows that the access synchronization sequence of the embodiment of the present application has strong resistance to Doppler frequency shift and can still achieve accurate detection under low signal-to-noise ratios.

[0121] Corresponding to the above method embodiments, the present application also provides a computer program product, including a computer program, which, when executed by a processor, implements the access synchronization sequence construction method, access synchronization sequence detection method or base station access method described in any of the above embodiments.

[0122] This application also provides a base station, such as Figure 13 As shown, the electronic device includes:

[0123] Processor 1301;

[0124] Memory 1302 for storing processor-executable instructions;

[0125] The processor 1301 is configured to implement the access synchronization sequence construction method and the access synchronization sequence detection method described in any one of the above embodiments.

[0126] This application also provides a terminal device, such as Figure 14 As shown, the electronic device includes:

[0127] Processor 1401;

[0128] Memory 1402 for storing processor-executable instructions;

[0129] The processor 1401 is configured to implement the method for accessing a base station described in any one of the above embodiments.

[0130] The present application also provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the method for constructing an access synchronization sequence, the method for detecting an access synchronization sequence, or the method for accessing a base station described in any of the above embodiments is implemented.

[0131] The above is only a specific implementation method of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A method for constructing an access synchronization sequence, characterized in that: Applied to a base station, the method includes: A first initial sequence set is constructed based on a plurality of first initial sequences that satisfy low correlation, and a second initial sequence set is constructed based on a plurality of second initial sequences that satisfy low correlation; wherein satisfying low correlation includes: the sequences themselves satisfying low autocorrelation, and the sequences satisfying low mutual correlation; A Kronecker product operation is performed on any two initial sequences from the first initial sequence set and the second initial sequence set to obtain several target sequences, and a set of access synchronization sequences for distribution to user terminals is constructed based on the target sequences.

2. The method according to claim 1, characterized in that The sequence types of the first initial sequence include a Zadov-Chu sequence, a longest linear shift register sequence, and a cubic phase polynomial Alltop sequence; the sequence types of the second initial sequence include a Zadov-Chu sequence, a longest linear shift register sequence, and an Alltop sequence; The first initial sequence and the second initial sequence are of different sequence types.

3. The method according to claim 1, characterized in that The performing a Kronecker product operation on any two initial sequences respectively from the first initial sequence set and the second initial sequence set comprises: The first initial sequence from the first initial sequence set is used as the outer sequence of the Kronecker product, the second initial sequence from the second initial sequence set is used as the inner sequence of the Kronecker product, and a Kronecker product operation is performed between the first initial sequence and the second initial sequence.

4. The method according to claim 1, wherein The method further comprises: cyclically shifting the target sequence to obtain a cyclically shifted sequence; The constructing a set of access synchronization sequences for distribution to the user terminal includes: The set of access synchronization sequences is constructed based on the target sequence and the cyclically shifted sequence.

5. A method for detecting an access synchronization sequence based on the method according to any one of claims 1 to 4, characterized in that: Applied to a base station; the first initial sequence is used as an outer sequence when performing the Kronecker product operation, and the second initial sequence is used as an inner sequence when performing the Kronecker product operation; the method comprising: Receiving an access synchronization sequence to be detected from a user terminal, wherein the access synchronization sequence to be detected is constructed based on the method according to any one of claims 1 to 4 and distributed to the user terminal; performing correlation operations on the access synchronization sequence to be detected and each inner sequence in the second initial sequence set to obtain correlation operation results; Performing a dot product operation on the correlation operation result and each outer sequence in the first initial sequence set to obtain a dot product operation result; Based on the dot product result, the ID of the user terminal and the first path delay between the user terminal and the base station are detected, so as to enable the user terminal to access based on the ID and the first path delay.

6. The method according to claim 5, characterized in that The correlation operation result and the dot product operation result are both in matrix form, wherein the correlation operation result corresponds to a first matrix and the dot product operation result corresponds to a second matrix; obtaining the dot product operation result includes: Perform a point multiplication operation on each column of the first matrix and each outer sequence in the first initial sequence set, and perform a fast Fourier transform on the columns of the first matrix to obtain the second matrix.

7. The method according to claim 6, characterized in that The detecting the ID of the user terminal and the first path delay between the user terminal and the base station includes: Based on the second matrix, determining a preset number of access synchronization sequences having the highest correlation with the access synchronization sequence to be detected from the set of access synchronization sequences; performing correlation operations on the preset number of access synchronization sequences and the access synchronization sequence to be detected, and performing fast Fourier transform on each of the access synchronization sequences to obtain the preset number of correlation vectors; If a target correlation vector exists among the preset number of correlation vectors, and the modulus of the target correlation vector is greater than a preset modulus threshold, the ID and the first path delay are detected based on the target correlation vector; wherein the modulus of the target correlation vector is the maximum value among the preset number of correlation vectors.

8. A method for accessing a base station, characterized in that: Applied to a user terminal; the method comprises: receiving an indication message sent by a base station, where the indication message is used to instruct the user terminal to select an access synchronization sequence; Based on the indication message, determining a target access synchronization sequence from a set of access synchronization sequences constructed by the method according to any one of claims 1 to 4; The target access synchronization sequence is sent to the base station, so as to access the base station based on the target access synchronization sequence.

9. The method according to claim 8, characterized in that The user terminal pre-stores the first initial sequence set and the second initial sequence set according to any one of claims 1 to 4; The indication message includes at least a first selection indication for a first target sequence in the first initial sequence set, and a second selection indication for a second target sequence in the second initial sequence set; The determining of the target access synchronization sequence includes: determining the first target sequence based on the first selection indication, and determining the second target sequence based on the second selection indication; A Kronecker product operation is performed on the first target sequence and the second target sequence to obtain a Kronecker product result, and the target access synchronization sequence is determined from the set of access synchronization sequences based on the Kronecker product result.

10. The method according to claim 9, characterized in that The indication message also includes a cyclic shift parameter; The determining the target access synchronization sequence from the set of access synchronization sequences based on the Kronecker product result includes: A cyclic shift operation is performed on the Kronecker product result based on the cyclic shift parameter to obtain a cyclically shifted Kronecker product result, and the target access synchronization sequence is determined based on the cyclically shifted Kronecker product result.

11. A base station, characterized in that: include: processor; a memory for storing processor-executable instructions; The processor is configured to implement the method according to any one of claims 1 to 7.

12. A terminal device, characterized in that: include: processor; a memory for storing processor-executable instructions; The processor is configured to implement the method according to any one of claims 8 to 10.

13. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 10 are implemented.

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