A positioning method based on asynchronous TDOA and double-antenna base station

Abstract

The application discloses a positioning method based on asynchronous TDOA and double-antenna base stations, which obtains the time difference of arrival (TDOA) of a ranging signal sent by a target node to reach two antennas on a base station, and then obtains a distance difference, so as to calculate the position coordinates of the target node. The method uses three double-antenna base stations, the length of the antennas can be adjusted according to needs, and the lengths of the two antenna feeders of the same base station are equal. When deployed, the antenna feeders of the three double-antenna base stations are parallel to the xyz coordinate axes. The method uses asynchronous base stations, and greatly reduces the implementation complexity and cost of the system. When solving the position coordinates of the target node, a unique solution can be obtained according to the geometric characteristics of the model and the spatial constraint conditions of the three distance differences. A large number of simulations and tests show that the method can achieve high positioning accuracy within the communication coverage range, and has broad application prospects in low-power wide-area networks (LPWAN).

Description

Technical Field

[0001] This invention relates to a wireless positioning method, specifically a positioning method based on asynchronous TDOA and a dual-antenna base station, belonging to the field of wireless communication technology. Background Technology

[0002] In recent years, with the advancement of wireless technology, target localization has become a key aspect of emerging applications in wireless sensor networks and the Internet of Things. The demand for wireless positioning and direction finding is increasingly significant, with many fields requiring location information. Global Positioning Systems (GPS, BDS, GLONASS, etc.) are one of the important positioning systems, widely used in outdoor environments. However, due to satellite signal blockage, the signal becomes very weak by the time it reaches indoors, making such positioning systems unsuitable for indoor environments. To overcome the positioning limitations of GPS and achieve accurate positioning in complex indoor environments, researchers both domestically and internationally have introduced indoor positioning technologies. Indoor positioning technologies are mainly divided into two categories: the first category is indoor positioning technology based on external signal sources. This type of technology relies on external signal sources, including computer vision, infrared, ultrasound, WiFi, Bluetooth, ultra-wideband (UWB), and pseudosatellites; the second category is indoor positioning technology based on natural signal sources. This type of technology relies solely on the terminal's sensors for positioning, including inertial navigation and geomagnetic navigation.

[0003] Among these positioning technologies, visual positioning, infrared, and ultrasonic technologies all suffer from limited signal coverage. While WiFi positioning offers improved coverage, its accuracy is insufficient, and due to the complex and variable indoor environment and severe non-line-of-sight phenomena, it is difficult to obtain an accurate signal strength attenuation model. Bluetooth positioning technology is susceptible to external noise interference, has poor signal stability, and a limited communication range. Pseudo-satellites are extremely difficult to deploy. Geomagnetic and inertial navigation systems only achieve meter-level accuracy. In summary, UWB signals, with their high transmission rate, low power consumption, and strong anti-interference capabilities, offer unparalleled positioning accuracy when applied to wireless positioning systems, making them a reliable choice for short-range wireless positioning.

[0004] However, UWB technology also has significant drawbacks, namely its short positioning range, which prevents it from functioning properly in some spacious indoor environments. Furthermore, UWB positioning uses a synchronous TDOA (Time Difference of Origin) positioning model. While TDOA offers advantages such as low power consumption and high positioning accuracy, it requires measuring the time difference between the target node and each pair of anchor nodes. Since the time difference method is affected by various factors, such as synchronization accuracy, harsh environments, and non-line-of-sight (NLOS) errors, it is difficult to accurately measure using traditional TDOA methods. Among these factors, synchronization accuracy is one of the main influencing factors on TDOA measurement. Existing solutions are all affected by time synchronization problems due to clock skew and drift. In addition, time synchronization is usually achieved through a large number of message exchanges between a set of anchor nodes, which can increase network load. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention proposes a positioning method based on asynchronous TDOA and dual-antenna base stations. The method obtains the time difference of arrival (TDOA) between the target node and the two antennas on the base station by using the ranging signal emitted by the target node. From this, the distance difference is obtained, and the position coordinates of the target node are calculated. This method requires at least three dual-antenna base stations. The antenna lengths can be adjusted as needed, and the two antenna feed lines of the same base station are of equal length. During deployment, the antenna feed lines of the three dual-antenna base stations are parallel to the x, y, and z coordinate axes, respectively. This method avoids the use of synchronous base stations, significantly reducing the system's implementation complexity and cost. When solving for the target node's position coordinates, a unique solution can be obtained based on the geometric characteristics of the model and the spatial constraints of the three distance differences.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0008] In a first aspect, the present invention provides a positioning method based on asynchronous TDOA and a dual-antenna base station, comprising:

[0009] In response to the target node transmitting a ranging signal, the distance difference between the target node and the dual antennas of each base station is obtained; wherein, the base station includes at least three dual-antenna base stations, and the length of the antenna feed lines at both ends of each base station is adjustable and the feed line lengths are equal;

[0010] Based on the distance difference between the target node and the dual antennas of each base station, a pre-constructed system of equations based on the law of cosines is used to solve the problem and obtain multiple solutions.

[0011] Based on the multiple solutions obtained, the solutions are eliminated according to the three distance difference formulas, and solutions with imaginary parts are also eliminated to obtain a unique solution and obtain the position coordinates of the target node to be measured.

[0012] The antenna feed lines at both ends of the three dual-antenna base stations are all at a 180-degree angle; the antenna feed lines at both ends of the first dual-antenna base station are parallel to the x-axis, the antenna feed lines at both ends of the second dual-antenna base station are parallel to the y-axis, and the antenna feed lines at both ends of the third dual-antenna base station are parallel to the z-axis.

[0013] In some embodiments, the formula for the distance difference between the target node and the antennas at both ends of the base station BSi includes:

[0014]

[0015]

[0016]

[0017] Where Δr i L1 represents the distance difference between the target node and the dual antennas of base station BSi. BS1, BS2, and BS3 are three dual-antenna base stations. L1 and L2 are the antenna coordinates at both ends of base station BS1, L3 and L4 are the antenna coordinates at both ends of base station BS2, and L5 and L6 are the antenna coordinates at both ends of base station BS3. l represents the length of the antenna, and (x, y, z) are the position coordinates of the target node to be measured.

[0018] In some embodiments, the method for constructing a system of equations based on the law of cosines includes:

[0019] Based on the geometric relationships of the dual-antenna base station model, and using the law of cosines, a system of equations is established:

[0020]

[0021] Where l represents the length of the antenna, p i Let r be the distance from the target node to the base station BSi. 2i-1 Let r be the distance from the target node to antenna L2i-1. 2i-1 +Δr i Let θ be the distance from the target node to antenna L2i, where i = 1, 2, 3; L1 and L2 are the antenna coordinates at both ends of base station BS1, L3 and L4 are the antenna coordinates at both ends of base station BS2, and L5 and L6 are the antenna coordinates at both ends of base station BS3. i Let the angle between the antennas at both ends of the base station BSi and the target node be denoted by ; rearranging the equations, we get:

[0022] Where i = 1, 2, 3;

[0023] Δr iLet (x, y, z) be the distance difference between the target node and the base station BSi dual antennas, and (x, y, z) be the position coordinates of the target node to be measured. i ,y i ,z i ) represents the location coordinates of base station BSi.

[0024] In some embodiments, the target node to be tested is located in a space constrained by three distance difference constraints.

[0025] In some embodiments, the distance difference Δr between the target node and the base station BSi dual antennas i =r 2i-1 -r 2i The values ​​of i are 1, 2, 3, and can be positive or negative. The equation used to solve the system of equations is Δr. i 2 This leads to redundant solutions, which can be eliminated using the three distance difference formulas; at the same time, solutions with imaginary parts are also eliminated to obtain a unique solution.

[0026] Secondly, the present invention provides a positioning device based on asynchronous TDOA and dual-antenna base station, including a processor and a storage medium;

[0027] The storage medium is used to store instructions;

[0028] The processor is configured to operate according to the instructions to perform the steps of the method according to the first aspect.

[0029] Thirdly, the present invention provides a storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method described in the first aspect.

[0030] Fourthly, the present invention provides a computer device including one or more processors, one or more memories, and one or more programs, wherein the one or more programs are stored in the one or more memories and configured to be executed by the one or more processors, and the one or more programs include instructions for performing any of the methods described in the first aspect.

[0031] Beneficial Effects: The positioning method and apparatus based on asynchronous TDOA and dual-antenna base stations provided by this invention have the following advantages: The distance difference between the target node and the dual antennas is obtained by measuring the distance signal emitted by the target node, thereby calculating the position of the target node. This method employs a dual-antenna base station model with three base stations, each with two antennas, the length of which can be adjusted as needed. The deployment positions of the three dual-antenna base stations are parallel to the coordinate axes, avoiding the use of synchronous base stations and greatly reducing the implementation complexity of the nodes. Simultaneously, based on the geometric characteristics of the dual-antenna base stations, the cosine theorem and spatial constraints are introduced to eliminate the possibility of multiple solutions for the dual-antenna base station. After multiple simulation measurements, this method can achieve high positioning accuracy within the communication coverage area, thus showing good application prospects in LPWAN. Attached Figure Description

[0032] Figure 1 This is a model diagram of the positioning system according to an embodiment of the present invention.

[0033] Figure 2 This is a geometric diagram showing the relationship between the target node and the dual antennas in an embodiment of the present invention.

[0034] Figure 3 This is a three-dimensional surface intersection diagram according to an embodiment of the present invention.

[0035] Figure 4 These are simulation results of the three-dimensional positioning model in an embodiment of the present invention. Detailed Implementation

[0036] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0037] In the description of this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0038] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0039] Example 1

[0040] A positioning method based on asynchronous TDOA and a dual-antenna base station includes:

[0041] In response to the target node transmitting a ranging signal, the distance difference between the target node and the dual antennas of each base station is obtained; wherein, the base station includes at least three dual-antenna base stations, and the length of the antenna feed lines at both ends of each base station is adjustable and the feed line lengths are equal;

[0042] Based on the distance difference between the target node and the dual antennas of each base station, a pre-constructed system of equations based on the law of cosines is used to solve the problem and obtain multiple solutions.

[0043] Based on the multiple solutions obtained, the solutions are eliminated according to the three distance difference formulas, and solutions with imaginary parts are also eliminated to obtain a unique solution and obtain the position coordinates of the target node to be measured.

[0044] In some embodiments, including:

[0045] Step 1: Deploy three dual-antenna base stations, ensuring that the antenna feed lines of the three dual-antenna base stations are parallel to the x, y, and z coordinate axes, respectively;

[0046] Step 2: The target node transmits a ranging signal to obtain the distance difference between the target node and the dual antennas of each base station: Δr i =r 2i-1 -r 2i (i = 1, 2, 3);

[0047] Step 3: Based on the geometric relationships of the dual-antenna base station model, and using the law of cosines, establish the following system of equations:

[0048]

[0049] Where p i Let r be the distance from the target node to the base station BSi. 2i-1 Let r be the distance from the target node to antenna L2i-1. 2i-1 +Δr i Let L be the distance from the target node to antenna L2i (i = 1, 2, 3). Rearranging the equations, we get:

[0050] Where i = 1, 2, 3. Solving the above system of equations yields 8 solutions.

[0051] Step 4: Based on the three distance difference formulas and excluding solutions with imaginary parts, obtain the unique solution.

[0052] In some specific embodiments, the positioning method based on asynchronous TDOA and dual-antenna base stations includes the following steps:

[0053] 1. Base station model and problem modeling

[0054] Given: BS1, BS2, and BS3 are three dual-antenna base stations. L1 and L2 are the antenna coordinates at both ends of BS1, L3 and L4 are the antenna coordinates at both ends of BS2, and L5 and L6 are the antenna coordinates at both ends of BS3. L1 and L2 are parallel to the X-axis, L3 and L4 are parallel to the Y-axis, and L5 and L6 are parallel to the Z-axis (see appendix for details). Figure 1 l represents the length of the antenna feed line.

[0055] Base station BS1, antennas L1(x1-ly1z1), L2(x1+ly1z1);

[0056] Base station BS2, antennas L3(x2 y2-l z2), L4(x2 y2+l z2);

[0057] Base station BS3, antennas L5(x3 y3 z3-l), L6(x3 y3 z3+l);

[0058] Find the position MS(x,y,z) of the target node MS.

[0059] 2. Establish a system of equations based on the geometric model of a dual-antenna base station.

[0060] The distances from the target node MS to each antenna at both ends of the base station BSi (i = 1, 2, 3) are as follows (see details). Figure 2 ):

[0061]

[0062]

[0063]

[0064]

[0065]

[0066]

[0067] The formula for the distance difference between the target node MS and the antennas at both ends of the base station BSi (i = 1, 2, 3) is as follows (see details). Figure 2 ):

[0068]

[0069]

[0070]

[0071] Based on the geometric relationships of the dual-antenna base station model, such as Figure 2 As shown, using the Law of Cosines, the following system of equations can be established:

[0072]

[0073] Where p i Let r be the distance from the target node to the base station BSi. 2i-1 Let r be the distance from the target node to antenna L2i-1. 2i-1 +Δr i For the distance from the target node to antenna L2i (i = 1, 2, 3), see... Figure 2 .

[0074] Taking i=1 as an example:

[0075] From ① we get: Substituting ③ into ②, we get:

[0076]

[0077]

[0078] ⑤-④ yielded:

[0079] (r1+Δr1) 2 -r1 2 =(x1+l) 2 -(x1-l) 2 -2x(x1+l)+2x(x1-l)

[0080] Summarized as follows:

[0081]

[0082] Solving the system of equations ⑥ and ⑦ yields:

[0083]

[0084] Similarly, when i = 2 and i = 3, we can obtain the following system of equations:

[0085]

[0086] 3. Solve for p1 2 p2 2 p3 2 The system of equations formed by these equations yields solutions for x, y, and z.

[0087] Based on the physical model used in this method, the coordinates of the target node are the intersection points of three hyperboloids. This can be determined from the spatial intersecting properties of hyperboloids (see...). Figure 3 The intersection of two hyperboloids forms a transaction line, and the intersection of three hyperboloids forms a transaction point. There may be multiple intersection points of three hyperboloids, with a maximum of 8.

[0088] 4. By incorporating model-based geometric properties and spatial constraints based on three distance differences, redundant solutions are eliminated to obtain the target point coordinates.

[0089] Distance difference Δr i =r 2i-1 -r 2i (i = 1, 2, 3), the values ​​can be positive or negative, and Δr is used in solving the system of equations. i 2 This leads to redundant solutions, which can be eliminated by the three distance difference formulas. Simultaneously, solutions with imaginary parts are also eliminated, resulting in a unique solution.

[0090] Simulation Case

[0091] Assuming the target node MS coordinates are (70, 70, -80) and the antenna feed line length l is 20 (all units are meters), the spatial coordinates of the three dual-antenna base stations are shown in the table below:

[0092]

[0093] Based on the distance difference between the target node MS and the antennas at both ends of the base station BSi (i = 1, 2, 3) obtained by measurement (as described in step 2 above), under the condition of no error, 8 valid real solutions for (x, y, z) are obtained. According to the three distance difference formulas, redundant solutions can be eliminated, and the MS positioning coordinates (70, 70, -80) are obtained. They are the same as the assumed MS coordinates, indicating that the positioning is successful.

[0094] All eight solutions obtained in the above cases are real solutions, and redundant solutions can be eliminated simply by using the three distance difference formulas. However, in a few cases, imaginary solutions may exist, which indicate that there are no solutions and need to be eliminated, as shown below:

[0095] Assuming the target node MS coordinates are (120, 100, -30), and the antenna feeder length and the deployment positions of the three dual-antenna base stations remain unchanged, under error-free conditions, we obtain 8 solutions for each of (x, y, z). Among these 8 solutions, there are invalid imaginary solutions that need to be eliminated. Combining this with the three distance difference formulas, redundant solutions are eliminated, and the MS positioning coordinates (120, 100, -30) are obtained, indicating successful positioning.

[0096] Because of factors such as noise and multipath propagation in the real environment, the measured distance difference will have a certain error. Taking the first case mentioned above as an example, when the measurement error is (-0.5, 0.5) meters, simulations were performed on Matlab, and after multiple tests, the positioning results are as follows. Figure 4 As shown, the green circle represents the actual position of the MS (Mobile Suit), and the red asterisk represents the final location. It is clear that the results of multiple positioning attempts are dispersed around the actual MS position. The final positioning error ranges are as follows: X-coordinate error range is (-0.56, 1.8) meters, Y-coordinate error range is (-0.43, 1.19) meters, and Z-coordinate error range is (-1.04, -0.76) meters. All errors are within acceptable ranges, indicating that the positioning accuracy of this method meets the requirements. To further optimize the positioning accuracy, multiple calculations can be performed and the average value taken to achieve better positioning results.

[0097] Example 2

[0098] Secondly, this embodiment provides a positioning device based on asynchronous TDOA and a dual-antenna base station, including a processor and a storage medium;

[0099] The storage medium is used to store instructions;

[0100] The processor is configured to operate according to the instructions to perform the steps of the method according to Embodiment 1.

[0101] Example 3

[0102] Thirdly, this embodiment provides a storage medium on which a computer program is stored, which, when executed by a processor, implements the steps of the method described in Embodiment 1.

[0103] Example 4

[0104] Fourthly, this embodiment provides a computer device including one or more processors, one or more memories, and one or more programs, wherein the one or more programs are stored in the one or more memories and configured to be executed by the one or more processors, and the one or more programs include instructions for performing any of the methods described according to Embodiment 1.

[0105] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0106] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0107] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0108] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0109] It should be noted that the above embodiments are illustrative of the present invention and not restrictive of the present invention, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims.

Claims

1. A positioning method based on asynchronous TDOA and a dual-antenna base station, characterized in that, include: In response to the target node transmitting a ranging signal, the distance difference between the target node and the dual antennas of each base station is obtained; wherein, the base station includes at least three dual-antenna base stations, and the length of the antenna feed lines at both ends of each base station is adjustable and the feed line lengths are equal; Based on the distance difference between the target node and the dual antennas of each base station, a pre-constructed system of equations based on the law of cosines is used to solve the problem and obtain multiple solutions. Based on the multiple solutions obtained, the solutions are eliminated according to the three distance difference formulas, and solutions with imaginary parts are also eliminated to obtain a unique solution and obtain the position coordinates of the target node to be measured. Among them, the methods for constructing systems of equations based on the Law of Cosines include: Based on the geometric relationships of the dual-antenna base station model, and using the law of cosines, a system of equations is established as follows: Where l represents the length of the antenna, i = 1, 2, 3, p i Let Δr be the distance from the target node to the i-th base station BSi. i r represents the distance difference between the target node and the base station BSi dual antennas. 2i-1 Let r be the distance from the target node to antenna L2i-1. 2i-1 +Δr i Let L1 be the distance from the target node to antenna L2i, L2 be the antenna coordinates at both ends of base station BS1, L3 be the antenna coordinates at both ends of base station BS2, L5 be the antenna coordinates at both ends of base station BS3, and θ be the distance from the target node to antenna L2i. i Let the angle between the antennas at both ends of the base station BSi and the target node be denoted by ; rearranging the equations, we get: Where (x,y,z) are the position coordinates of the target node to be measured, (x i ,y i ,z i ) represents the location coordinates of base station BSi.

2. The positioning method based on asynchronous TDOA and dual-antenna base station according to claim 1, characterized in that, The antenna feed lines at both ends of the three dual-antenna base stations are all at a 180-degree angle; the antenna feed lines at both ends of the first dual-antenna base station are parallel to the x-axis, the antenna feed lines at both ends of the second dual-antenna base station are parallel to the y-axis, and the antenna feed lines at both ends of the third dual-antenna base station are parallel to the z-axis.

3. The positioning method based on asynchronous TDOA and dual-antenna base station according to claim 1, characterized in that, The formula for the distance difference between the target node and the antennas at both ends of the base station BSi includes: Where Δr i Let x be the distance difference between the target node and the base station BSi dual antennas. i ,y i ,z i (x, y, z) represents the location coordinates of base station BSi, BS1, BS2, and BS3 are three dual-antenna base stations, L1 and L2 are the antenna coordinates at both ends of base station BS1, L3 and L4 are the antenna coordinates at both ends of base station BS2, and L5 and L6 are the antenna coordinates at both ends of base station BS3; l represents the length of the antenna, and (x, y, z) represents the location coordinates of the target node to be measured.

4. The positioning method based on asynchronous TDOA and dual-antenna base station according to claim 1, characterized in that, The target node to be tested is located in the space constrained by three distance difference constraints.

5. The positioning method based on asynchronous TDOA and dual-antenna base station according to claim 1, characterized in that, Distance difference Δr between the target node and the base station BSi dual antennas i =r 2i-1 -r 2i The values ​​of i are 1, 2, 3, and can be positive or negative. The equation used to solve the system of equations is Δr. i 2 This leads to redundant solutions, which can be eliminated using the three distance difference formulas; at the same time, solutions with imaginary parts are also eliminated to obtain a unique solution.

6. A positioning device based on asynchronous TDOA and a dual-antenna base station, characterized in that, Including processor and storage media; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to perform the steps of the method according to any one of claims 1 to 5.

7. A storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 5.

8. A computer device, characterized in that, It includes one or more processors, one or more memories, and one or more programs, wherein the one or more programs are stored in the one or more memories and configured to be executed by the one or more processors, and the one or more programs include instructions for performing any one of the methods according to claims 1 to 5.

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