TDOA positioning method based on multiple long feeder antennas and single base station

Abstract

The invention relates to the technical field of wireless communication, in particular to a TDOA (Time Difference of Arrival) positioning method based on a single base station with multiple long feeder antennas, which comprises the following steps: deploying a base station, leading out six long feeder antennas towards the periphery by taking the base station as a circle center, forming a group by every two antennas of the six antennas of the base station, and totally forming three groups of antenna pairs, the angle of each group of antenna pairs can be changed as required, and the length of each antenna can be changed as required; a to-be-measured target node transmits a ranging signal, the distance difference between the target node and the two ends of the base station antenna pair is obtained, and the to-be-measured target node is located in the space constrained by the constraint condition; analyzing the distance difference between the target node and the two ends of the base station antenna pair according to the geometrical relationship of the spherical coordinate system model; and according to three distance difference formulas, excluding a solution with an imaginary part to obtain a unique solution, and breaking through the limitation of a rectangular coordinate axis so as to facilitate the deployment of the base station in a real scene.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and in particular to a TDOA positioning method based on a single base station with multiple long feeder antennas. Background Art

[0002] In recent years, with the continuous development of wireless technology, the application of target positioning in wireless sensor networks and the Internet of Things has become increasingly critical. The demand for wireless positioning and direction finding has gradually increased, and the requirements for location information in various fields have been increasing. As one of the main positioning systems, the global satellite positioning system (such as GPS, BDS, GLONASS, etc.) has been widely used in outdoor environments. However, these systems cannot operate normally indoors because satellite signals are blocked and attenuated indoors. In order to compensate for this shortcoming, researchers have proposed various indoor positioning technologies.

[0003] Indoor positioning technology can be divided into two categories: one is based on external information sources, and the other is based on internal information sources. The former relies on external devices to achieve positioning, mainly including computer vision, infrared, ultrasound, WiFi, Bluetooth, Ultra Wide Band (UWB) and pseudo-satellite technologies; the latter relies on the device's own sensors for positioning, including inertial navigation and geomagnetic navigation.

[0004] Each type of positioning technology has its own advantages and disadvantages. The signal coverage of visual, infrared and ultrasonic positioning technologies is relatively small; although WiFi positioning has a larger coverage, the positioning accuracy is insufficient, and the complex indoor environment will affect the accuracy of the signal strength model; Bluetooth positioning is susceptible to noise interference, the signal stability is poor, and the communication range is limited; pseudo-satellite technology is complex to deploy; the accuracy of geomagnetic and inertial navigation can only reach the meter level. In this context, UWB technology has shown significant advantages in short-distance wireless positioning with its high transmission rate, low power consumption and strong anti-interference ability, and has become a reliable choice.

[0005] Although UWB technology has the above advantages, its positioning range is limited and may not work properly in a wide indoor environment. In addition, UWB positioning technology uses a synchronized TDOA (Time Difference of Arrival) model. Although this model has the advantages of low power consumption and high accuracy, it relies on measuring the time difference between the target node and each anchor node. The traditional TDOA method is easily affected by factors such as time synchronization accuracy, environmental conditions, and non-line-of-sight propagation (NLOS), making it difficult to accurately measure the time difference. Among them, the accuracy of time synchronization is one of the main factors affecting TDOA measurements. Due to clock skew and drift, existing solutions are inevitably affected by time synchronization problems. In addition, time synchronization usually requires a large number of message exchanges between anchor nodes, which increases the network burden.

[0006] In summary, although indoor positioning technology has made up for the shortcomings of satellite positioning systems in indoor environments to a certain extent, each technology has its limitations. UWB technology shows significant advantages in short-distance, high-precision positioning, but there are still some technical challenges to overcome in wide indoor environments and time synchronization. Future research directions may include improving time synchronization methods, reducing network burdens, and improving positioning accuracy in complex environments to achieve wider applications.

[0007] On the other hand, most current positioning models rely on the rectangular coordinate system to establish positioning equations, which means that the positioning model is limited by the coordinate representation of the rectangular coordinate system, which limits the layout of base station antennas. In many cases, they must be deployed parallel to the rectangular coordinate axis. When deploying this model in real scenarios, it is difficult to deploy base stations in accordance with the requirements of the model, due to the influence of the geographical environment and terrain, where two long feeder antennas are deployed parallel to the rectangular coordinate axis. Once the angle deviates, the base station needs to be redeployed. Summary of the invention

[0008] The purpose of the present invention is to provide a TDOA positioning method based on a single base station with multiple long feeder antennas to solve the problems raised in the above background technology.

[0009] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0010] Step 1: Deploy the base station, and extend six long feeder antennas around the base station as the center. Every two antennas of the six base station antennas that pass through the center of the circle face each other to form a group, forming three antenna pairs in total. The angle of each antenna pair can be changed as needed, and the length of each antenna can be changed as needed;

[0011] Step 2: The target node to be measured transmits a ranging signal to obtain a distance difference between the target node and both ends of the base station antenna pair, wherein the target node to be measured is located in a space constrained by the constraint condition;

[0012] Step 3: Analyze the distance difference between the target node and the two ends of the base station antenna pair according to the geometric relationship of the spherical coordinate system model;

[0013] Step 4: According to the three distance difference formulas and excluding the solutions with imaginary parts, a unique solution is obtained.

[0014] Preferably, when deploying a base station, six long feeder antennas are extended from the base station as the center to the surrounding areas. Every two antennas of the six antennas of the base station that pass through the center of the circle relative to each other form a group, forming a total of three antenna pairs. The angle of each antenna pair can be changed as needed, and the length of each antenna can be changed as needed. The specific positioning system model is as follows:

[0015] It is known that the base station BS is located at the original center, and T1, T2, T3, T4, T5, and T6 are antenna coordinates derived from the base station BS. T1 and T6 pass through the original center relative to each other to form a pair of antennas; T3 and T4 pass through the original center relative to each other to form a pair of antennas; T5 and T6 pass through the original center relative to each other to form a pair of antennas (see the attached figure for details). Figure 2 ). P is the measured point, and its coordinates in the spherical coordinate system are The coordinates of the two ends of each antenna pair of the base station in the spherical coordinate system are (i=1,2,3,4,5,6; j=1,2,3,4,5,6).

[0016] Preferably, during positioning, the target node to be measured transmits a ranging signal to obtain the distance difference between the target node and the dual antennas of each base station:

[0017]

[0018] According to the geometric relationship of the dual-antenna base station model, using the cosine theorem, the following equations are established:

[0019]

[0020] Where Δr ij The target node P is connected to the base station antenna pair T i , T j The coordinates of the target node P in the spherical coordinate system are The coordinates of the two ends of each antenna pair of the base station in the spherical coordinate system are Solving the above system of equations can yield 8 solutions.

[0021] Preferably, according to the geometric model used by the present method, the target node coordinates are the intersection points of three hyperbolic surfaces. According to the characteristics of the intersection of hyperbolic surfaces in space, two hyperbolic surfaces intersect at a line, and three hyperbolic surfaces intersect at a point. There may be multiple intersection points of the three hyperbolic surfaces, up to 8.

[0022] Preferably, the distance difference Δr ij =r i -r j , which can be positive or negative, and Δr is used in solving the equations. ij 2 , resulting in redundant solutions. The three distance difference formulas can eliminate the redundant solutions. At the same time, the solutions with imaginary parts are eliminated to obtain the only solution.

[0023] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0024] The present invention obtains the arrival time difference (TDOA) of the target node to each antenna pair on the base station through the ranging signal sent by the target node to be measured, thereby obtaining the distance difference, and thus calculating the position coordinates of the target node to be measured; when deploying the base station, the method uses the base station as the center of the circle to lead out six long feeder antennas to the surrounding areas, and the six antennas of the base station are formed into a group of two antennas that pass through the original center relative to each other, and a total of three antenna pairs are formed, and the angle of each antenna pair can be changed as needed, and the length of each antenna can be changed as needed; the method avoids using a synchronous base station, greatly reducing 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 constraints of the three distance differences; the method transforms the positioning model from the rectangular coordinate system to the spherical coordinate system, breaking through the limitation of the rectangular coordinate axis, so as to facilitate the deployment of base stations in real scenes. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0026] Figure 1 It is a flow chart of a TDOA positioning method based on a single base station with multiple long feeder antennas according to the present invention;

[0027] Figure 2 It is a model diagram of the positioning system of the present invention.

[0028] Figure 3 This is the spherical coordinate system model diagram of the present invention

[0029] Figure 4 It is a geometric relationship diagram from the target node to both ends of the antenna pair of the present invention.

[0030] Figure 5 It is the simulation result of the three-dimensional positioning model of the present invention. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] See also Figure 1-Figure 5 , the present invention provides a technical solution:

[0033] Embodiment 1:

[0034] The present invention discloses a TDOA positioning method based on a single base station with multiple long feeder antennas in a spherical coordinate system. The distance difference between the target node and the two ends of the antenna pair is obtained through the ranging signal emitted by the target node to be measured, so as to calculate the position of the target node to be measured. This method adopts a multi-antenna single base station model. When deploying the base station, six long feeder antennas are drawn out from the base station as the center of the circle to the surrounding areas. The six antennas of the base station are formed into a group of two antennas that pass through the original center relative to each other, forming a total of three antenna pairs. The angle of each antenna pair can be changed as needed, and the length of each antenna can be changed as needed, thereby avoiding the synchronization problem of the base station and greatly reducing the implementation complexity of the node. At the same time, the cosine theorem and space constraints are introduced according to the geometric characteristics described by the multi-antenna single base station relying on the three-dimensional spherical coordinate system, eliminating the situation where there are multiple solutions for the multi-antenna single base station. After multiple simulation measurements, this method can achieve a high positioning accuracy within the communication coverage range, so it has a good application prospect in LPWAN.

[0035] The TDOA positioning method based on a single base station with multiple long feeder antennas in a spherical coordinate system specifically includes the following steps:

[0036] Step 1: Base station model and problem modeling:

[0037] It is known that the base station BS is located at the original center, and T1, T2, T3, T4, T5, and T6 are antenna coordinates derived from the base station BS. T1 and T6 pass through the original center relative to each other to form a pair of antennas; T3 and T4 pass through the original center relative to each other to form a pair of antennas; T5 and T6 pass through the original center relative to each other to form a pair of antennas (see the attached figure for details). Figure 2 ).

[0038] The coordinates of the antenna measurement point in the spherical coordinate system are:

[0039]

[0040]

[0041]

[0042]

[0043]

[0044]

[0045] Solve the coordinates of the target node P in the spherical coordinate system as follows: The geometric relationship of the spherical coordinate system model is detailed in the attached Figure 3 .

[0046] Step 2: Establish a set of equations based on the geometric model of a multi-antenna single base station:

[0047] From the law of cosines, we know that: PT i 2 =r 2 +r i 2 -2rr i cosα i ,PT j 2 =r 2 +r j 2 -2rr j cosα j ,in The distances from the target node P to both ends of each antenna pair of the base station are as follows (see Appendix for details). Figure 4 ):

[0048]

[0049] The formula for the distance difference between the target node P and the two ends of the antenna pair on the base station BS is as follows (see the attached Figure 2 ):

[0050]

[0051]

[0052]

[0053] Combined with the cosine theorem, we get the following system of equations:

[0054]

[0055] Where Δr ij The target node P is connected to the base station antenna pair T i , T j The coordinates of the target node P in the spherical coordinate system are The coordinates of the two ends of each antenna pair of the base station in the spherical coordinate system are

[0056] Take i=1, j=6 as an example:

[0057]

[0058] Similarly, when i=2, j=4; i=3, j=5, we can get the following equations:

[0059]

[0060] Step 3: Solve for Δr 16 , Δr 24 , Δr 35 The system of equations composed of r, θ, Solution

[0061] According to the physical model used in this method, the target node coordinates are the intersection points of three hyperboloids. According to the characteristics of the intersection of hyperboloids in space, two hyperboloids intersect at a line, and three hyperboloids intersect at a point. There may be multiple intersection points of three hyperboloids, up to 8.

[0062] Step 4: Add spatial constraints based on the geometric characteristics of the model and the three distance differences, eliminate redundant solutions, and obtain the coordinates of the target point.

[0063] Distance difference Δr ij =r i -r j , which can be positive or negative, and Δr is used in solving the equations. ij 2 , resulting in redundant solutions. The three distance difference formulas can eliminate the redundant solutions. At the same time, the solutions with imaginary parts are eliminated to obtain a unique solution.

[0064] The following is a simulation case of the present invention:

[0065] Assume that the target node MS coordinates are (60, 30, 30), the antenna feeder length l is 20 (all in meters), and the spatial coordinates of each antenna on the base station are shown in the following table:

[0066]

[0067] Table 1

[0068] According to the measurement, the target node MS to the base station antenna pairs are obtained

[0069] The distance difference of (i=1,2,3,4,5,6; j=1,2,3,4,5,6) (as described in step 2) is obtained. In the absence of error, the MS positioning coordinates (60, 30, 30) are obtained, which are the same as the assumed MS coordinates, indicating that the positioning is successful.

[0070] When the antenna layout needs to be changed according to the environment, the angle and length of the antenna can be changed as needed. Assuming that the target node MS coordinates are (60, 30, 30), the antenna feeder length l is different (units are meters), the spatial coordinates of each antenna on the base station are shown in the following table:

[0071]

[0072] Table 2

[0073] According to the measurement, the target node MS to the base station antenna pairs are obtained

[0074] The distance difference of (i=1,2,3,4,5,6; j=1,2,3,4,5,6) (as described in step 2) is calculated. In the absence of error, the MS positioning coordinates (60, 30, 30) are obtained, which are the same as the assumed MS coordinates, indicating that the positioning is successful.

[0075] Because there are noise, multipath and other influencing factors in the actual environment, the distance difference obtained by measurement will have a certain error. Taking the first case above as an example, when the measurement error is (-0.5, 0.5) meters, simulation is performed on Matlab. After multiple tests, the positioning results are as shown in the attached figure. Figure 5 As shown in the figure, the green circle represents the actual position of the MS, the red asterisk represents the final position, and the measured point MS and the positioning results are mapped to the three-dimensional rectangular coordinate system. It can be clearly seen that the results of multiple positioning are scattered around the actual position of the MS. The final positioning error range is as follows: the X coordinate error range is (-0.14, 0.1) meters, the Y coordinate error range is (-0.62, 0.84), and the Z coordinate error range is (-0.52, 0.3) meters. The errors are all within the acceptable range, which shows that the positioning accuracy of this method meets the requirements. If you want to further optimize the positioning accuracy, you can perform multiple calculations and take the average to achieve a better positioning effect.

[0076] Embodiment 2:

[0077] The computer-readable storage medium of this embodiment stores a computer program thereon, and when the program is executed by a processor, the steps of a TDOA positioning method based on a single base station with multiple long feeder antennas in embodiment 1 are implemented.

[0078] The computer-readable storage medium of this embodiment may be an internal storage unit of the terminal, such as a hard disk or memory of the terminal; the computer-readable storage medium of this embodiment may also be an external storage device of the terminal, such as a plug-in hard disk, a smart memory card, a secure digital card, a flash memory card, etc. equipped on the terminal; further, the computer-readable storage medium may also include both an internal storage unit of the terminal and an external storage device.

[0079] The computer-readable storage medium of this embodiment is used to store computer programs and other programs and data required by the terminal. The computer-readable storage medium can also be used to temporarily store data that has been output or is to be output.

[0080] Embodiment 3:

[0081] The computer device of this embodiment includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the steps of a TDOA positioning method based on a single base station with multiple long feeder antennas in Embodiment 1 are implemented.

[0082] In this embodiment, the processor may be a central processing unit, or other general-purpose processors, digital signal processors, application-specific integrated circuits, readily available programmable gate arrays or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc. The memory may include a read-only memory and a random access memory, and provide instructions and data to the processor. A portion of the memory may also include a non-volatile random access memory. For example, the memory may also store information about the device type.

[0083] Those skilled in the art will appreciate that the disclosed content of the embodiments may be provided as methods, systems, or computer program products. Therefore, the present solution may adopt the form of hardware embodiments, software embodiments, or embodiments combining software and hardware. Moreover, the present solution may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage and optical storage, etc.) containing computer-usable program codes.

[0084] The present solution is described with reference to the method according to the embodiment of the present solution and the flowchart and / or block diagram of the computer program product. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions; these computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 one or more processes and / or methods Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0085] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 one or more processes and / or methods Figure 1 A function specified in one or more boxes.

[0086] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 one or more processes and / or methods Figure 1 The steps for the functions specified in one or more boxes.

[0087] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium, and when the program is executed, it can include the processes of the embodiments of the above-mentioned methods. The storage medium can be a disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM).

[0088] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A TDOA positioning method based on a single base station with multiple long feeder antennas, characterized in that: The method comprises: Step 1: Deploy the base station, and extend six long feeder antennas around the base station as the center. Every two antennas of the six base station antennas that pass through the center of the circle face each other to form a group, forming three antenna pairs in total. The angle of each antenna pair can be changed as needed, and the length of each antenna can be changed as needed; Step 2: The target node to be measured transmits a ranging signal to obtain a distance difference between the target node and both ends of the base station antenna pair, wherein the target node to be measured is located in a space constrained by the constraint condition; Step 3: Analyze the distance difference between the target node and the two ends of the base station antenna pair according to the geometric relationship of the spherical coordinate system model; Step 4: According to the three distance difference formulas and excluding the solutions with imaginary parts, a unique solution is obtained.

2. A TDOA positioning method based on a single base station with multiple long feeder antennas as claimed in claim 1, characterized in that: The step 1 comprises: A base station with six long feeder antennas is used, and the base station model is based on a three-dimensional spherical coordinate system to establish a positioning equation group. It can be expanded to a base station with multiple long feeder antennas according to needs. In the positioning method, a multi-antenna base station can be expanded to multiple multi-antenna base stations for distributed positioning according to needs: Assume that the base station BS is located at the center of the circle, and T1, T2, T3, T4, T5, and T6 are the antenna coordinates derived from the base station BS; Among them, T1 and T6 pass through the original center relative to each other to form a pair of antennas; T3 and T4 pass through the original center relative to each other to form a pair of antennas; T5 and T6 pass through the original center relative to each other to form a pair of antennas.

3. The TDOA positioning method based on a single base station with multiple long feeder antennas according to claim 1, characterized in that: The step 3 comprises: According to the geometric relationship of the spherical coordinate system model, using the cosine theorem, the following set of equations is established: Where Δr ij The antenna pair T from the target node P to the base station i , T j The coordinates of the target node P to be measured in the spherical coordinate system are Then the coordinates of the two ends of each antenna pair of the base station in the spherical coordinate system are At this time, 8 solutions can be obtained by solving the above equations.

4. The TDOA positioning method based on a single base station with multiple long feeder antennas according to claim 1, characterized in that: The step 4 comprises: Distance difference formula Δr ij =r i -r j , where i = 1, 2, 3, 4, 5, 6; j = 1, 2, 3, 4, 5, 6; i ≠ j; Δr ij The value of can be positive or negative, and Δr is used in solving the equations. ij 2 , resulting in redundant solutions. The three distance difference formulas can eliminate redundant solutions and solutions with imaginary parts to obtain a unique solution.

5. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps in a TDOA positioning method based on a single base station with multiple long feeder antennas as described in any one of claims 1-4 are implemented.

6. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps in the TDOA positioning method based on a single base station with multiple long feeder antennas as described in any one of claims 1-5 are implemented.

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