Positioning method

Abstract

To improve the accuracy of positioning a target node.SOLUTION: A method determines a position of a target node on the basis of radio signals transmitted and received between the target node and one or more reference nodes. The method acquires values of different positioning-related parameters estimated from the radio signals. The method determines an error of a positioning value of the target node calculated on the basis of a value of each of the different positioning-related parameters on the basis of at least one of the positioning value and a past determined position of the target node. The method determines a weight of each of the different positioning-related parameters on the basis of the error. The method determines the position of the target node on the basis of the positioning value calculated on the basis of the weight and the value of each of the different positioning-related parameters.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present invention relates to a positioning method. [Background technology]

[0002] The radio frequencies used by mobile phones are planned to be expanded to increasingly higher frequency bands in the future, and for example, the millimeter wave and terahertz wave bands are expected to be used more in the 5G evolution and 6G systems that will be put to practical use in the future. Utilizing these high frequency bands is essential for increasing the speed and capacity of communications, but at the same time, there is an issue that the communication distance of radio waves becomes shorter as the frequency becomes higher.

[0003] Therefore, for example, in the 5G evolution and 6G systems, small cell base stations are expected to be used frequently in addition to macro cell base stations. A highly reliable communication network will be realized by directing directional beams in the millimeter wave and terahertz wave bands to user terminals from small cell base stations densely installed indoors.

[0004] It is believed that positioning of user terminals will be possible by utilizing densely-spaced base stations. In other words, if the coordinates of each base station are known in advance, the position of the user terminal can be calculated geometrically by referring to the angle of the beam that the base station directs toward the user terminal and the arrival time of the radio waves based on those coordinates. It is predicted that this system will enable highly accurate positioning with a positioning error of less than a few centimeters.

[0005] A two-step method is known as a conventional wireless positioning method, in which a positioning-related parameter is acquired by communicating between a target object such as a user terminal and a reference point such as a base station, and a position is estimated based on the positioning-related parameter. Two-step positioning methods using various types of positioning-related parameters are known. For example, an example of a technique that employs time difference of arrival as a positioning-related parameter is disclosed in JP2012-98071A. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2012-98071 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, a positioning method using a communication infrastructure in which small cell base stations are densely arranged has not been realized. When considering a positioning system using such a communication infrastructure, the inventors extracted the problems to be solved, considered specific solutions, and came up with the invention. That is, a problem with the conventional positioning method is that there are places in the positioning area where the positioning accuracy is good and places where the positioning accuracy is bad, depending on the arrangement pattern of the reference points and the presence or absence of obstacles in the positioning area.

[0008] In positioning systems that utilize high-density installation environments of small cell base stations such as 5Gevolution and 6G, the base stations are not necessarily arranged in a regular grid pattern, but many base stations are likely to be arranged in irregular three-dimensional coordinates. In addition, urban areas and indoors are severe multipath environments surrounded by many obstacles.

[0009] Therefore, if the positioning of a user terminal is performed using a conventional positioning method, the positioning error distribution within the positioning area will be very complex, and as a result, it is thought that there will be many points where the positioning accuracy drops significantly. [Means for solving the problem]

[0010] One aspect of the present disclosure is a method for determining a position of a target node based on a radio signal transmitted and received between the target node and one or more reference nodes, comprising: obtaining values ​​of different positioning-related parameters estimated from the radio signal; determining an error in a positioning value of the target node calculated based on the values ​​of each of the different positioning-related parameters based on the positioning value and at least one of a past determined position of the target node; determining a weight for each of the different positioning-related parameters based on the error; and determining the position of the target node based on the weight and the values ​​of each of the different positioning-related parameters. Effect of the Invention

[0011] According to one aspect of the present invention, the positioning accuracy of a target node can be improved. [Brief description of the drawings]

[0012] [Figure 1] 1 illustrates a schematic configuration of a positioning system according to an embodiment of the present specification. [Diagram 2] FIG. 2 is a block diagram illustrating a schematic configuration of a terminal. [Diagram 3] FIG. 2 is a block diagram showing the functional configuration of a base station. [Figure 4] 2 illustrates an example of a functional configuration of a positioning device. [Diagram 5] 2 shows an example of the hardware configuration of a positioning device. [Figure 6] 1 shows a sequence diagram for transmitting and receiving information on the angle of arrival (AOA) of a positioning signal in a positioning system. [Figure 7] 1 shows a sequence diagram for transmitting and receiving information on the time of arrival (TOA) of a positioning signal in a positioning system. [Figure 8] 1 shows a sequence diagram for transmitting and receiving information on the time difference of arrival (TDOA) of a positioning signal in a positioning system. [Figure 9] 2 illustrates a schematic diagram of information flow among a terminal, a base station, and a positioning device in a positioning system for performing positioning of the terminal. [Figure 10] 1 is an example of a flowchart illustrating an overview of a terminal positioning method performed by a positioning device. [Figure 11] A more specific example of the positioning method of the terminal 30 according to the positioning method of FIG. 10 will be described. [Figure 12] 13 is another example of a flowchart illustrating an overview of a terminal positioning method by a positioning device. [Figure 13] An example of a more specific positioning method for a terminal according to the positioning method of FIG. 12 will be described. [Figure 14] An example of a more specific positioning method for a terminal according to the positioning method of FIG. 12 will be described. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] In the following, when necessary for convenience, the description will be divided into multiple sections or examples, but unless otherwise specified, they are not unrelated to each other, and one is related to the other as a partial or complete modification, detail, supplementary explanation, etc. Furthermore, in the following, when the number of elements, etc. (including the number, numerical value, amount, range, etc.) is mentioned, it is not limited to the specific number, and may be more or less than the specific number, unless otherwise specified or clearly limited in principle to a specific number, etc.

[0014] A method for locating a target node by wireless communication between a target node that is an object of positioning and a reference node will be described below. The reference node is, for example, a small cell base station, and may be arranged geometrically irregularly.

[0015] Various positioning-related parameters for locating the target node are known, and there are also various positioning methods based on them. Depending on the placement of the reference node and the presence or absence of electromagnetic obstacles in the positioning area, the accuracy of any positioning method is not uniform throughout the positioning area, and each positioning method has its own unique error distribution. Therefore, the optimal positioning method differs depending on the location within the positioning area.

[0016] A positioning method according to an embodiment of the present specification adaptively determines the weight (contribution) of each of a plurality of different positioning methods for the position of a target node. The position of the target node is estimated based on the weights of the different positioning methods and the positioning values. This makes it possible to obtain good positioning accuracy throughout the entire positioning area. EXAMPLES

[0017] 1 is a schematic diagram showing a configuration of a positioning system according to an embodiment of the present specification. The positioning system 1 includes base stations 21, 22, and 23, and a positioning device 10. The positioning system 1 performs positioning of a terminal 30 and identifies its position (xe, ye, ze). In the example described below, the three-dimensional position of the terminal 30 is measured, but in other examples, the two-dimensional position may be measured.

[0018] In this specification, the terminal 30, which is the object to be positioned, may be called a target node, and the base stations 21, 22, and 23 may be called reference nodes. The terminal 30 is a mobile object and may move within the positioning area of ​​the positioning system 1. The positions (x1, y1, z1), (x2, y2, z2), and (x3, y3, z3) of the base stations 21, 22, and 23 are registered in advance and are fixed.

[0019] The base stations 21, 22, and 23 and the positioning device 10 transmit and receive information via a network 40. The network 40 may have any configuration using wired or wireless communication, and may include, for example, an optical fiber backhaul network, a wireless backhaul network using millimeter waves or terahertz waves, a LAN, or a WAN.

[0020] The terminal 30 includes a function of transmitting a radio signal (positioning signal) 35 for measuring the position of the terminal 30. The base stations 21, 22, and 23 each include a function of estimating (generating) a predetermined positioning-related parameter from the positioning signal 35 transmitted by the terminal 30. In FIG. 1, one positioning signal is indicated by the reference symbol 35. The positioning signals transmitted to the base stations 21, 22, and 23 may be the same or different. Note that the positioning signal in this specification may be a data communication packet itself exchanged between a terminal and a base station in cellular communication, or may be a packet transmitted and received only for terminal positioning.

[0021] The positioning-related parameters will be described in detail later, but for example, the positioning-related parameters may include the received signal strength (RSS), time of arrival (TOA), and angle of arrival (AOA) of the positioning signal 35. These are examples of preferred positioning-related parameters. Furthermore, the base stations 21, 22, and 23 may have a function of determining the time difference of arrival (TDOA) between the time of arrival at another base station and the time of arrival at the base station itself as a positioning-related parameter.

[0022] The positioning device 10 includes a database (not shown in FIG. 1) that stores coordinate information of each of the base stations 21, 22, and 23. The database can store information related to the positioning system other than the coordinate information. The positioning device 10 is connected to each of the base stations 21, 22, and 23 via a network 40. The positioning device 10 calculates the position of the terminal 30 using positioning-related parameters obtained from each of the base stations 21, 22, and 23 via the network 40 and information included in the database.

[0023] In the configuration example described below, the positioning device 10 calculates the position of the terminal 30, but in other configuration examples, other devices, such as a base station or a terminal, may obtain information necessary to calculate the position of the terminal and calculate the position.

[0024] 2 is a block diagram showing a schematic configuration of the terminal 30. The terminal 30 includes a signal transmission control unit 301, a signal creation unit 302, and an antenna 303. The signal transmission control unit 31 determines that the terminal 30 transmits a positioning signal based on a signal for positioning received from a base station, information from a sensor or a timer in the terminal 30, and the like. The signal creation unit 302 creates a positioning signal upon receiving an instruction from the signal transmission control unit 301, and transmits the signal from the antenna 303. This positioning signal has an identifier uniquely assigned to each terminal 30, and it is possible to identify which terminal 30 transmitted the positioning signal.

[0025] The hardware configuration of the terminal 30 may include, for example, a processor which is an arithmetic processing device, a memory which is a storage device for storing programs executed by the processor and data referenced by the processor, a signal processing circuit which performs predetermined signal processing, a wireless interface, and an antenna. The hardware configuration for realizing each function of the terminal 30 is arbitrary, and each functional unit may be implemented by one or more of the above hardware components.

[0026] Fig. 3 is a block diagram showing the functional configuration of the base station 21, 22, or 23. Fig. 3 shows only functional blocks related to positioning in a small cell base station of a mobile phone system. In the example described below, the base stations 21, 22, or 23 have a common configuration, but in other configuration examples, they may have different configurations.

[0027] The base station includes a positioning-related parameter measurement unit 201, a signal transmission source determination unit 202, a positioning-related parameter notification creation unit 203, a communication unit 204, a memory 205, and an antenna 206. The positioning-related parameter measurement unit 201 measures the positioning-related parameters of the positioning signal 35 transmitted from the terminal 30. The base station measures a plurality of positioning-related parameters. In the example described below, the positioning-related parameters include the arrival angle, arrival time, and arrival time difference of the positioning signal. Different packets may be used for measuring different positioning-related parameters, or different positioning-related parameters may be measured from a common packet.

[0028] The positioning-related parameter measurement unit 201 sends the obtained information to the positioning-related parameter notification creation unit 203. The positioning-related parameter notification creation unit 33 creates a positioning-related parameter notification message including the positioning-related parameters of the positioning signal 35 and information for identifying the terminal 30 that is the transmission source.

[0029] The communication unit 204 functions as an interface that connects the base station to the network 40. The communication unit 204 transmits the positioning related parameter notification message created by the positioning related parameter notification creating unit 203 to the positioning device 10 via the network 40.

[0030] The hardware configuration of the base station may include, for example, a processor which is an arithmetic processing device, a memory which is a storage device for storing programs executed by the processor and data referenced by the processor, a signal processing circuit which performs predetermined signal processing, a wireless interface, and an antenna. The hardware configuration for realizing each function of the base station is arbitrary, and each functional unit may be implemented by one or more of the above hardware components.

[0031] 4 shows an example of a functional configuration of the positioning device 10. The positioning device 10 includes a position calculation unit 101, a communication unit 102, and a positioning system information database 103. The positioning system information database 103 stores information about the positioning system 1 to be referenced for positioning, including coordinate information of base stations. As will be described later, the positioning system information database 103 can store, for example, a pre-measurement error distribution over the entire positioning area for each of different positioning methods.

[0032] The communication unit 102 functions as an interface that connects the positioning device 10 to the network 40, and receives positioning-related parameter notifications sent from the base stations 21, 22, and 23, and sends them to the position calculation unit 101. The position calculation unit 101 calculates the current position of the terminal 30 based on the positioning-related parameters included in the positioning-related parameter notifications and the position information of the base stations 21, 22, and 23 obtained from the positioning system information database 103.

[0033] As will be described later, the position calculation unit 101 determines weights (degrees of contribution in determining the position of the terminal 30) of the positions (positioning values) of the terminal 30 estimated from different positioning-related parameters. The position calculation unit 101 determines the position of the terminal 30 based on the weights and the positioning values. Details of the determination of the position of the terminal 30 by the position calculation unit 101 will be described later.

[0034] 5 shows an example of a hardware configuration of the positioning device 10. The positioning device 10 may have, for example, a computer configuration. Specifically, the positioning device 10 includes a processor 151 which is an arithmetic processing device, and a DRAM 152 which is a main storage device providing a volatile temporary storage area for storing programs and data executed by the processor 151.

[0035] The positioning device 10 may further include an auxiliary storage device 153 that provides a permanent information storage area using a hard disk drive (HDD) or a flash memory, and an interface 156 such as a serial port for data communication with other devices. The positioning device 10 may also include an input device such as a mouse or a keyboard for operation, and an output device for presenting the output results of each process to the user.

[0036] The programs executed by the processor 151 and data to be processed are loaded from the auxiliary storage device 213 to the DRAM 152. The functions of the positioning device 10 may be distributed among multiple computers. Thus, the positioning device 10 includes one or more storage devices and one or more processors.

[0037] At least a part of the functions of the positioning device 10 can be realized by the processor 151 executing a program recorded in the auxiliary storage device 153. The positioning system information database 103 can be implemented by the processor 151 executing a program that stores data in the auxiliary storage device 213.

[0038] The positioning device 10 may be a physical computer system (one or more physical computers) as described above, or may be constructed on a group of computing resources (multiple computing resources) such as a cloud platform. The computer system or the group of computing resources includes one or more interface devices (including, for example, a communication interface device and an input / output device), one or more storage devices (including, for example, a memory (main memory) and an auxiliary storage device), and one or more processors.

[0039] When a function is realized by a program being executed by a processor, the defined processing is performed using a storage device and / or an interface device, etc. as appropriate, and therefore the function may be at least a part of the processor. Processing described with a function as the subject may be processing performed by a processor or a system having the processor. The program may be installed from a program source. The program source may be, for example, a program distribution computer or a computer-readable storage medium (for example, a computer-readable non-transitory storage medium). The description of each function is an example, and multiple functions may be combined into one function, or one function may be divided into multiple functions.

[0040] The positioning device 10 of this embodiment estimates the current position (positioning value) of the terminal 30 from different positioning-related parameters. The positioning device 10 determines a weight for the positioning value (positioning-related parameter) based on at least one of the positioning value and a previously determined position of the terminal 30. The positioning device 10 determines the current position of the terminal 30 based on the weights of the different positioning-related parameters and the positioning value. Before describing a method for determining the position of the terminal 30 by the positioning device 10, a method for collecting positioning-related parameters by the positioning device 10 will be described.

[0041] In the example described below, the positioning device 10 determines an estimated position of the terminal 30 using the arrival angle, arrival time, and arrival time difference of the positioning signal from the terminal 30 as positioning-related parameters. Note that the positioning-related parameters used by the positioning device 10 for position estimation are not limited to these, and some of these may be omitted or other positioning-related parameters may be used. For example, the signal strength of the positioning signal is one of the available positioning-related parameters.

[0042] Fig. 6 shows a sequence diagram of transmitting and receiving information on the angle of arrival (AOA) of a positioning signal in the positioning system 1. The terminal 30 transmits a positioning signal 35 to each of the base stations 21, 22, and 23. In Fig. 6, one positioning signal is indicated by the reference symbol 35 as an example.

[0043] To obtain the AOA, the base station or terminal must have the ability to scan a directional beam. The most common configuration is one in which the base station has a beam scanning function and the terminal emits an omnidirectional (isotropic) electric field. In this case, the base station first emits a calling signal to the terminal while scanning the directional beam, and the terminal returns a response signal when it receives the calling signal.

[0044] This allows the base station to know at what angle the terminal responded when the calling signal was sent, and as a result, the AOA of the positioning signal. In Figure 6, the broken arrows indicate the wireless signals sent from terminal 30 to base stations 21, 22, and 23, respectively, and this is a schematic representation of the above procedure.

[0045] The base stations 21, 22, and 23 each determine the arrival angle of the positioning signal 35 from the received positioning signal 35. For example, the antenna 206 has an array configuration, and the positioning-related parameter measurement unit 201 can measure (estimate) the arrival angle of the positioning signal 35 based on the phase difference of the received positioning signal 35. The base stations 21, 22, and 23 each transmit information on the arrival angles AOA1, AOA2, and AOA3 to the positioning device 10 via the network 40.

[0046] It should be noted that any other known method for determining the arrival angles may be used. The positioning device 10 may obtain information required for calculating the arrival angles AOA1, AOA2, and AOA3 from the base stations 21, 22, and 23, respectively, and determine the arrival angles AOA1, AOA2, and AOA3.

[0047] Fig. 7 shows a sequence diagram of transmitting and receiving information on the time of arrival (TOA) of a positioning signal in the positioning system 1. The base stations 21, 22, and 23 each transmit a signal for positioning to the terminal 30 (not shown in Fig. 7). The terminal 30 transmits positioning signals 351, 352, and 353 to the base stations 21, 22, and 23, respectively, in response to the received signal.

[0048] The base stations 21, 22 and 23 respectively determine arrival times TOA1, TOA2 and TOA3 of the positioning signals from the received positioning signals 351, 352 and 353. The arrival times are the times it takes for a signal to reach the base station from the terminal 30.

[0049] The positioning-related parameter measurement unit 201 measures, for example, the time (RTT: Round Trip Time) from when a positioning signal is transmitted to the terminal 30 until a response signal (positioning signal) is received from the terminal 30. The arrival time can be calculated (estimated) by subtracting the time lag from reception to transmission at the terminal from the RTT and dividing the result by two. As another method, under the condition that the built-in timers of the terminal and the base station are accurately synchronized, the terminal writes the transmission time in the positioning signal, and the base station compares the reception time of the transmission signal with the written transmission time to obtain the TOA. The base stations 21, 22, and 23 transmit information on arrival times TOA1, TOA2, and TOA3, respectively, to the positioning device 10 via the network 40.

[0050] It should be noted that any other known method for determining the arrival times may be used. The positioning device 10 may obtain information required for calculating the arrival times TOA1, TOA2, and TOA3 from the base stations 21, 22, and 23, respectively, and determine the arrival times TOA1, TOA2, and TOA3.

[0051] 8 shows a sequence diagram of transmitting and receiving information on the time difference of arrival (TDOA) of a positioning signal in the positioning system 1. The time difference of arrival is the difference between the time of arrival (TOA) of one base station and the time of arrival (TOA) of another base station.

[0052] The terminal 30 transmits a positioning signal 35 to each of the base stations 21, 22, and 23. In Fig. 8, one positioning signal is indicated by the reference symbol 35 as an example. The base stations 21, 22, and 23 measure times RT1, RT2, and RT3 at which they receive the positioning signal 35, respectively. The positioning-related parameter measurement unit 201 can measure the reception time of the positioning signal 35 by referring to a built-in timer.

[0053] Next, in response to receiving the positioning signal 35, the base station 21 wirelessly transmits a reference signal 36 to each of the other base stations 22 and 23. The delay time required from receiving the positioning signal 35 to transmitting the reference signal 36 is constant and is stored in advance in the positioning system information database 103 of the positioning device 10.

[0054] The base station 22 measures the reception time of the reference signal 36 from the base station 21, and calculates the difference RT12 between the reception time RS2 and the reception time RT2 of the positioning signal 35 at the base station 22. The base station 22 transmits the time difference RT12 to the positioning device 10 via the network 40. The base station 23 measures the reception time of the reference signal 36 from the base station 21, and calculates the difference RT13 between the reception time RS3 and the reception time RT3 of the positioning signal 35 at the base station 23. The base station 23 transmits the time difference RT13 to the positioning device 10 via the network 40.

[0055] The positioning device 10 calculates (estimates) a time difference of arrival TDOA12 between the base station 21 and the base station 22 based on the time difference RT12 and the delay time at the base station 21. Similarly, the positioning device 10 calculates (estimates) a time difference of arrival TDOA13 between the base station 21 and the base station 23 based on the time difference RT13 and the delay time at the base station 21.

[0056] It should be noted that any other known method for determining the time difference of arrival may be used. For example, the positioning device 10 may obtain the reception times RT2 and RS2 and RT3 and RS3 from the base stations 22 and 23, and determine the time differences of arrival TDOA12 and TDOA13 based on them.

[0057] 9 is a schematic diagram showing the flow of information among the terminal 30, the base stations 21, 22, and 23, and the positioning device 10 for performing positioning of the terminal 30 in the positioning system 1. The information obtained by each of the components in FIG. 9 corresponds to the description with reference to the sequence diagrams in FIGS. 6, 7, and 8.

[0058] Base station 21 obtains information on arrival angle AOA1 and arrival time TOA1 through communication with terminal 30. Similarly, base station 22 obtains information on arrival angle AOA2 and arrival time TOA2 through communication with terminal 30, and base station 23 obtains information on arrival angle AOA3 and arrival time TOA3 through communication with terminal 30.

[0059] Base station 22 obtains information on the time difference of arrival TDOA 12 between base stations 21 and 22 through communication with terminal 30 and base station 21. Similarly, base station 23 obtains information on the time difference of arrival TDOA 12 between base stations 21 and 23 through communication with terminal 30 and base station 21. Note that the information obtained by base stations 22 and 23 is the difference in the reception times of positioning signals, but since the time difference of arrival can be found from these values, the information communicated is essentially considered to be the time difference of arrival.

[0060] The positioning device 10 obtains information on the arrival angle AOA1 and arrival time TOA1 from the base station 21. The positioning device 10 obtains information on the arrival angle AOA2 and arrival time TOA2 from the base station 22, as well as information on the time difference of arrival TDOA12 between the base stations 21 and 22. The positioning device 10 obtains information on the arrival angle AOA3 and arrival time TOA3 from the base station 23, as well as information on the time difference of arrival TDOA13 between the base stations 21 and 23.

[0061] A method for determining the position of the terminal 30 by the positioning device 10 will be described below. In the configuration example described below, the positioning device 10 determines the position of the terminal 30. In other configuration examples, other devices including an interface, a processor, and a storage device, for example, the terminal 30 or a base station, may determine the position of the terminal 30 by a similar process.

[0062] A method according to an embodiment of the present specification determines weights of positioning results of different positioning-related parameters (different positioning methods), and determines the location of the terminal 30 based on the positioning results and weights. Depending on the arrangement of base stations and the presence or absence of electromagnetic obstacles in the positioning area, the positioning accuracy of each positioning method is not uniform throughout the entire positioning area, but has a unique distribution.

[0063] If only one positioning method is always used, areas with large positioning errors will occur depending on the placement of base stations and the positions of obstacles. As described in this specification, by adaptively varying the weights (contributions) of multiple positioning methods with different positioning error distributions within a positioning area to suit the conditions of the terminal, good positioning accuracy can be obtained throughout the entire positioning area.

[0064] The weight of the positioning method is determined based on the error of the positioning value by each positioning method. In the configuration example described below, the likelihood of the positioning position, the difference between the positioning value and a value derived from an autoregressive equation of past positioning results, and a pre-registered prior measurement error distribution are referenced as information representing the error of the positioning value.

[0065] In the following, the angle of arrival (AOA), time of arrival (TOA) and time difference of arrival (TDOA) are used as positioning related parameters. Positioning related parameters other than these, such as received signal strength (RSS), may be used, or at least some of the positioning related parameters may be omitted.

[0066] 10 is an example of a flowchart showing an outline of a positioning method of the terminal 30 by the positioning device 10. The position calculation unit 101 acquires a plurality of different positioning related parameters from a plurality of base stations as described above (S11). The positioning related parameters transmitted from the base stations are received by the communication unit 102 via the communication interface 154 and stored in a storage device, for example, the DRAM 152 or the auxiliary storage device 153. The position calculation unit 101 acquires the positioning related parameters from the storage device. As described above, the positioning related parameters acquired in this example are the angle of arrival (AOA), the time of arrival (TOA), and the time difference of arrival (TDOA).

[0067] Next, the position calculation unit 101 determines the weight of each of the positioning related parameters (S12). The weight of the positioning related parameters is the weight of the positioning value of the terminal 30 calculated from the positioning related parameters. The weight is determined based on the positioning value of the terminal 30 obtained from the values ​​of the positioning related parameters. The method of calculating the weight will be described in detail later.

[0068] Next, the position calculation unit 101 executes a positioning calculation using the values ​​of the positioning related parameters based on the weights of the respective positioning related parameters (S13). This calculation produces a positioning result 60 indicating the current position of the terminal 30. The method of the positioning calculation using the weights and the positioning related parameters will be described in detail later.

[0069] As described above, by performing positioning calculations for terminal 30 based on the weights of the positioning-related parameters and determining its location, it is possible to perform more appropriate positioning throughout the entire positioning area according to the environment in which terminal 30 is located.

[0070] Fig. 11 shows a more specific example of a positioning method for terminal 30 according to the positioning method of Fig. 10. Position calculation unit 101 acquires values ​​of angle of arrival (AOA), time of arrival (TOA) and time difference of arrival (TDOA) as values ​​of positioning-related parameters (S11A).

[0071] Next, the position calculation unit 101 determines weights for the angle of arrival (AOA), time of arrival (TOA), and time difference of arrival (TDOA) (S12A). To determine the weights, the position calculation unit 101 calculates the positioning value (current estimated position coordinates) of the terminal 30 from the values ​​of the acquired positioning-related parameters. Various methods of positioning calculation using each positioning-related parameter are known. For example, the position calculation unit 101 can calculate the positioning value of the terminal 30 (estimate the position (coordinates)) from the values ​​of the positioning-related parameters by a geometric method or a statistical method.

[0072] The geometric method can determine, for example, in a two-dimensional space, the intersection of three circles calculated from the positions of three base stations and their arrival times or reception strengths as the measured position of the terminal 30. Also, the intersection of lines calculated from the positions of two base stations and their arrival angles can be determined as the measured position of the terminal 30. Also, the intersection of two hyperbolas obtained from two arrival time differences can be determined as the measured position coordinate of the terminal 30.

[0073] The statistical method determines the positioning value based on the likelihood calculated from the values ​​of the positioning-related parameters. The likelihood indicates the accuracy of the positioning value, and the point where the likelihood value is maximum is determined as the positioning value (position coordinates) of the terminal 30. The likelihood is defined by a predetermined function. For example, the likelihood P(x, y, z) when TDOA positioning is performed is expressed by the following formula.

[0074]

number

[0075] Here, vc is the speed of light. The coordinates (xe,ye,ze) of the terminal 30 are (x,y,z) where P(x,y,z) is maximum. As the above formula shows, the likelihood P is defined by the error between the measured value and the theoretical value of TDOA. Similarly, likelihood functions can be defined for other positioning related parameters, and the point where the likelihood is maximum is determined as the positioning value (position coordinates) of the terminal 30. Note that the number of base stations from which the measurement related parameters are obtained is not limited.

[0076] As shown in Fig. 11, the position calculation unit 101 calculates a TOA positioning value from the arrival times (TOA) from a plurality of base stations (S21), and further calculates the likelihood of the TOA positioning value (S22). Here, the position calculation unit 101 determines the TOA positioning value by a statistical method. For example, the position calculation unit 101 calculates likelihood from the arrival times TOA1, TOA2, and TOA3 of three base stations 21, 22, and 23 and their position coordinates, and determines the position where the value is maximum as the positioning value of the terminal 30. The maximum likelihood value is the likelihood value of the TOA positioning position.

[0077] Similarly, the position calculation unit 101 calculates an AOA positioning value from angles of arrival (AOAs) from multiple base stations (S23), and further calculates the likelihood of the AOA positioning value (S24). The position calculation unit 101 determines the AOA positioning value by a statistical method. For example, the position calculation unit 101 calculates likelihood from angles of arrival AOA1, AOA2, and AOA3 of three base stations 21, 22, and 23 and their position coordinates, and determines the position where the value is maximum as the positioning value of the terminal 30. The maximum likelihood value is the likelihood value of the AOA positioning position.

[0078] Similarly, the position calculation unit 101 calculates an SDOA positioning value from the time difference of arrival (TDOA) from multiple base stations (S25), and further calculates the likelihood of the TDOA positioning value (S26). The position calculation unit 101 determines the TDOA positioning value by a statistical method. For example, the position calculation unit 101 calculates the likelihood from the time differences of arrival TDOA12 and TDOA13 from two base stations 22 and 23 and the position coordinates of three base stations 21, 22, and 23, and determines the position where the value is maximum as the positioning value of the terminal 30. The maximum likelihood value is the likelihood value of the TDOA positioning position.

[0079] Next, the position calculation unit 101 determines weights of the positioning related parameters based on the TOA likelihood value, the AOA likelihood value, and the TDOA likelihood value. In this example, the position calculation unit 101 selects the positioning related parameter (positioning method) with the maximum likelihood value (S27). That is, the position calculation unit 101 assigns a weight of 0 to the positioning related parameters other than the positioning related parameter with the maximum likelihood value.

[0080] Next, the position calculation unit 101 performs positioning calculation using the positioning related parameters based on the weights. Here, the position calculation unit 101 adopts the positioning value of the positioning method with the maximum likelihood value (S13A). The positioning method with the maximum likelihood value is the positioning method estimated to have the smallest error. By selecting the positioning method with the maximum likelihood value, the current position of the terminal 30 can be accurately determined with a small amount of calculation.

[0081] As described above, selecting one positioning method (positioning-related parameter) means that in determining the position of the terminal 30, the ratio (weight) of the positioning value by one positioning method is set to 1, and the ratio (weight) of the positioning value by the other positioning method is set to 0. In an example different from the above example, a ratio greater than 0 according to a likelihood value is given to each of the different positioning methods. This allows the positioning values ​​of the different positioning methods to be mixed according to their likelihood, and the current position of the terminal 30 to be accurately determined. EXAMPLES

[0082] Another example of the positioning method of the terminal 30 will be described. Fig. 12 is another example of a flowchart showing an overview of the positioning method of the terminal 30 by the positioning device 10. The position calculation unit 101 acquires a plurality of different positioning related parameters from a plurality of base stations (S31). The positioning related parameters transmitted from the base stations are stored in, for example, the DRAM 152 or the auxiliary storage device 153. The position calculation unit 101 acquires the positioning related parameters from the storage device. As described above, the positioning related parameters acquired in this example are the angle of arrival (AOA), the time of arrival (TOA), and the time difference of arrival (TDOA).

[0083] Next, the position calculation unit 101 determines a weight for each of the positioning related parameters (S32). The weight for the positioning related parameters is the weight for the positioning value of the terminal 30 calculated from the positioning related parameters. The weight is determined based on the positioning value of the terminal 30 obtained from the value of the positioning related parameters and past positioning results. By feeding back the past positioning results to the determination of the weight, the weight can be appropriately determined. The method of calculating the weight will be described in detail later.

[0084] Next, the position calculation unit 101 executes a positioning calculation using the values ​​of the positioning related parameters based on the weights of the respective positioning related parameters (S33). This calculation produces a positioning result 60 indicating the current position of the terminal 30. The method of positioning calculation using the weights and the positioning related parameters will be described in detail later.

[0085] Fig. 13 shows an example of a more specific positioning method for terminal 30 according to the positioning method of Fig. 12. Position calculation unit 101 acquires values ​​of angle of arrival (AOA), time of arrival (TOA) and time difference of arrival (TDOA) as values ​​of positioning-related parameters (S31A).

[0086] Next, the position calculation unit 101 determines weights for the angle of arrival (AOA), time of arrival (TOA), and time difference of arrival (TDOA) (S32A). To determine the weights, the position calculation unit 101 calculates the positioning value (current estimated position coordinates) of the terminal 30 from the values ​​of each of the acquired positioning-related parameters. The method of calculating the positioning value is as described with reference to FIG. 11, and a geometric method or a statistical method can be adopted.

[0087] The position calculation unit 101 calculates a TOA positioning value (S41) and autoregressively verifies the TOA positioning value (S42). The position calculation unit 101 also calculates an AOA positioning value (S43) and autoregressively verifies the AOA positioning value (S43). The position calculation unit 101 also calculates a TDOA positioning value (S45) and autoregressively verifies the TDOA positioning value (S46).

[0088] Next, the position calculation unit 101 determines weights for the three positioning methods based on the test results of the three positioning values ​​(S47). In this example, the weights indicate the mixing ratios of the positioning values ​​of the three positioning methods in determining the current position of the terminal 30. In the example described below, the mixing ratios of the positioning methods are greater than 0. Note that the mixing ratios of all but one positioning method being 0 means that the one positioning method is selected to determine the position of the terminal 30.

[0089] The autoregressive test, for example, fits a predetermined function to a predetermined number of previous positioning results in the coordinate space, for example, the previous three positioning results, and determines the distance (error) between the fitted line and the positioning value. The difference between the fitted line and the positioning value is the difference between the theoretical value based on the past determined positions and the positioning value, and is a statistical error. A larger blending ratio is assigned to the positioning value with a smaller distance.

[0090] In this way, past position measurements can be fed back into an autoregressive test to determine the appropriate ratio between different measurement methods. The fitting of a predetermined function can be, for example, a linear extrapolation, or a polynomial or other more complex basis function fitting. Alternatively, the value obtained by a Kalman filter can be used as a reference point.

[0091] Next, an example of determining the mixing ratio (weight) (S47) will be described. The distances between the fitted line and the TOA positioning value, the AOA positioning value, and the TDOA positioning value are respectively defined as d TOA , d AOA , d TDOA Let the ratio r TOA :r AOA :r TDOA For example, it can be calculated using the following formula: r TOA :r TOA :r TOA =1 / d TOA :1 / d AOA :1 / d TDOA

[0092] The method of calculating the positioning value by mixing the three positioning values ​​based on the mixing ratio can be calculated, for example, by the following formula. Here, the positioning value by mixing the three positioning values, the TOA positioning value, the AOA positioning value, the TDOA positioning value, and the mixing ratio are respectively (x, y, z), (x TOA ,y TOA ,z TOA ), (x AOA ,y AOA ,z AOA ), (x TDOA ,y TDOA ,z TDOA ), and (r TOA :r AOA :r TDOA )

[0093] x=x TOA *r TOA / (r TOA +r AOA +r TDOA ) +x AOA *r AOA / (rTOA +r AOA +r TDOA ) +x TDOA *r TDOA / (r TOA +r AOA +r TDOA ) y=y TOA *r TOA / (r TOA +r AOA +r TDOA ) +y AOA *r AOA / (r TOA +r AOA +r TDOA ) +y TDOA *r TDOA / (r TOA +r AOA +r TDOA ) z=z TOA *r TOA / (r TOA +r AOA +r TDOA ) +z AOA *r AOA / (r TOA +r AOA +r TDOA ) +z TDOA *r TDOA / (r TOA +r AOA +r TDOA )

[0094] In the method shown in Fig. 13, in the first step when the calculation process is started, since there are no past positioning values ​​to refer to, a predetermined initial value is given in advance. The initial value may be, for example, a mixture ratio (1:1:1) of TOA positioning values, AOA positioning values, and TDOA positioning values. As described with reference to Fig. 11, the most appropriate positioning method may be selected from the three positioning methods, and the positioning result may be determined as the position of the terminal 30.

[0095] In the following, a more specific example of a positioning method for the terminal 30 according to the positioning method of Fig. 12 will be described. The positioning method described below determines the weighting of each of the different positioning methods based on a pre-registered prior error distribution of the positioning area. By referring to the prior error distribution of the positioning area, the ratio of positioning values ​​with small errors is increased according to the location of the terminal 30, enabling highly accurate positioning.

[0096] Fig. 14 shows a more specific example of the positioning method of the terminal 30 according to the positioning method of Fig. 12. A pre-measurement error distribution 55 of the entire positioning area of ​​each of different positioning methods is stored in advance in the positioning system information database 103. The pre-measurement error distribution indicates the relationship between the coordinates and the measurement error in the positioning area. In this example, the pre-measurement error distributions of the TOA positioning method, the AOA positioning method, and the TDOA positioning method are registered. The pre-measurement error distribution differs for each positioning method, and is prepared separately for each.

[0097] For example, if the coordinates of the base station and the shape of the positioning area are known in advance, the theoretical value of the positioning error distribution in the entire positioning area can be calculated by statistical simulation. Alternatively, the advance measurement error distribution can be determined by actually performing positioning at various positions.

[0098] 14, first, the position calculation unit 101 acquires the values ​​of the angle of arrival (AOA), the time of arrival (TOA), and the time difference of arrival (TDOA) as the values ​​of the positioning related parameters (S31B). This step S31A is the same as step S31A in FIG.

[0099] Next, the position calculation unit 101 determines weights for the angle of arrival (AOA), time of arrival (TOA), and time difference of arrival (TDOA) (S32A). To determine the weights, the position calculation unit 101 calculates the positioning value of the terminal 30 from the values ​​of the acquired positioning-related parameters. The method of calculating the positioning value is as described with reference to FIG. 11, and a geometric method or a statistical method can be adopted.

[0100] In this example, the position calculation section 101 performs TOA positioning (S51), AOA positioning (S52) and TDOA positioning (S53) to determine the TOA positioning value, the AOA positioning value and the TDOA positioning value.

[0101] Furthermore, the position calculation unit 101 determines a weight for each of the positioning methods based on the past positioning results and the pre-measurement error distributions 55 of the TOA, AOA, and TDOA positioning methods (S54). In this example, the weight indicates a mixing ratio of the positioning values ​​of the three positioning methods in determining the current position of the terminal 30.

[0102] Specifically, the position calculation unit 101 refers to the pre-measurement error distributions 55 of the TOA, AOA, and TDOA positioning methods, respectively, and determines the measurement error of each of the positioning methods at the position of the immediately previous positioning result 60. The position calculation unit 101 determines a weight for each of the three positioning methods based on the positioning errors of each of the three positioning methods. The weight is determined so that the weight is larger for a positioning method with a smaller positioning error value. For example, in the method of calculating the mixture ratio described with reference to FIG. 13, the distance d may be replaced with the error.

[0103] The position calculation unit 101 executes positioning calculation using the three positioning related parameters based on the weights (mixing ratios) determined in step S54 (S33B). As described above, the previous positioning result 60 is fed back to the determination of the weights of the positioning methods (S32B). One or more previous positioning values ​​may be fed back.

[0104] In the method shown in Fig. 14, in the first step when the calculation process is started, since there are no past positioning values ​​to refer to, a predetermined initial value is given in advance. The initial value can be, for example, a mixture ratio (1:1:1) of TOA positioning values, AOA positioning values, and TDOA positioning values. As described with reference to Fig. 11, the most appropriate positioning method may be selected from the three positioning methods, and the positioning result may be determined as the position of the terminal 30.

[0105] As described with reference to the above several configuration examples, highly accurate positioning can be performed by adaptively varying the mixing ratio of positioning values ​​obtained by several positioning methods according to the situation in which the object to be positioned is placed.

[0106] The above positioning method can be applied to SI businesses and service businesses that utilize 5G evolution and 6G, for example, automatic operation of industrial robots and automated guided vehicles (AGVs) in factories, automatic control of robots to watch over children and the elderly in homes, management of people's movements and push-type services in commercial and public facilities, evacuation route guidance within buildings in the event of a disaster, etc.

[0107] The present invention is not limited to the above-mentioned embodiment, but includes various modified examples. For example, the above-mentioned embodiment has been described in detail to clearly explain the present invention, and is not necessarily limited to those including all of the configurations described. It is also possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.

[0108] In addition, the above-mentioned configurations, functions, processing units, etc. may be realized in part or in whole by hardware, for example, by designing them as integrated circuits. In addition, the above-mentioned configurations, functions, etc. may be realized in software by a processor interpreting and executing a program that realizes each function. Information such as the program, table, file, etc. that realizes each function can be stored in a memory, a recording device such as a hard disk or SSD (Solid State Drive), or a recording medium such as an IC card or SD card.

[0109] In addition, the control lines and information lines shown are those that are considered necessary for the explanation, and not all control lines and information lines in the product are necessarily shown. In reality, it can be considered that almost all components are connected to each other. [Explanation of symbols]

[0110] 1 Positioning System 10 Positioning device 21, 22, 23 base station 30 Terminals 31 Signal transmission control section 33 Positioning-related parameter notification creation unit 35 Radio signals (positioning signals) 36 Reference Signal 40 Network 55 Pre-measurement error distribution 60 Positioning results 101 Position calculation section 102 Communications Department 103 Positioning System Information Database 151 processor 153 Auxiliary storage device 154 Communication Interface 156 Interface 201 Positioning-related parameter measurement unit 202 Signal transmission source determination unit 203 Positioning-related parameter notification creation unit 204 Communications Department 205 Memory 206, 303 Antenna 213 Auxiliary storage 301 Signal transmission control section 302 Signal Creation Department 351, 352 Positioning signal

Claims

1. 1. A method for determining a location of a moving target node based on wireless signals transmitted and received between the target node and a number of fixed reference nodes, comprising: Obtaining measurements of positioning-related parameters of different positioning methods from the current wireless signal, the positioning-related parameters of the different positioning methods including at least two of an arrival angle, an arrival time, an arrival time difference, and a signal strength of the wireless signal; determining a maximum likelihood position as a current positioning value by each of the different positioning methods based on a likelihood function predefined for each of the different positioning methods and the measurement value of each of the different positioning methods; determining a mixing ratio greater than 0 for each of the different positioning methods based on an error between the current positioning value and a theoretical value based on a past positioning value and a predefined fitting function for each of the different positioning methods; determining a current location of the target node based on the mixing ratio and the current positioning values ​​of the different positioning methods.

2. 2. The method of claim 1 , The positioning related parameters of the different positioning techniques include angles of arrival, times of arrival, and time differences of arrival of the wireless signals.

3. 1. An apparatus for determining a location of a moving target node based on wireless signals transmitted and received between the target node and a plurality of fixed multi-reference nodes, comprising: A processing unit; a storage device; The storage device stores a likelihood function that is predefined for each of different positioning methods; The arithmetic processing device includes: Obtaining measurements of positioning-related parameters of the different positioning methods from the current wireless signals, the positioning-related parameters of the different positioning methods including at least two of an arrival angle, an arrival time, an arrival time difference, and a signal strength of the wireless signals; determining a maximum likelihood position as a current positioning value by each of the different positioning methods based on the likelihood function defined in advance for each of the different positioning methods and the measurement value of each of the different positioning methods; determining a mixing ratio greater than 0 for each of the different positioning methods based on an error between the current positioning value and a theoretical value based on a past positioning value and a predefined fitting function for each of the different positioning methods; determining a current location of the target node based on the mixing ratio and the current position measurements of the different positioning methods.

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