Multi-label positioning method and system based on variable receiving window

Abstract

The invention relates to the technical field of communication, and provides a multi-label positioning method and system based on a variable receiving window, and the method comprises the steps: a site sends a positioning request to a positioning label, and records the transmission time T1; the positioning tag records the receiving time T2, and sets the sending time T3 of the positioning signal according to the ID of the positioning tag; if the base station receives the positioning signal of the positioning label in the window period, recording a receiving timestamp T4, and opening the receiving window again; the base station receives the positioning reply signals and sends the positioning reply signals according to the sequence of T5; and if the positioning tag receives the positioning reply signal in the window period, recording the receiving time T6, and positioning according to T1-T6. According to the invention, real-time positioning between the base station and the plurality of positioning tags is realized through the variable receiving window, a dynamic queue mode is adopted, the collision probability of the positioning tags in air transmission is reduced, ordered communication of the plurality of positioning tags is realized, wiring construction is not needed, and the application scene is wide.

Description

Technical Field

[0001] The present invention relates to the field of communication technologies, and particularly to a multi-tag positioning method based on a variable reception window and a multi-tag positioning system based on a variable reception window. Background Art

[0002] The UWB (Ultra Wide Band)-based TOF (Time of Flight) positioning technology is a ranging-based method. By measuring the time required for a pulse signal to travel from transmission to reception (i.e., the time of flight), multiplying it by the propagation speed of the signal in the air, obtaining the round-trip distance, and then dividing by 2, the distance between the UWB positioning tag and the positioning base station is obtained.

[0003] In related technologies, given the coordinates of the base station, the position of the tag is generally calculated by the three-point positioning method. The key point of this method is to keep all anchors synchronized, that is, time synchronization. Time synchronization generally uses wired connections, which require cabling and network maintenance, and have limited and complex application scenarios. Moreover, interference will occur during multi-tag positioning, and collisions will occur when positioning tags are transmitted in the air, resulting in a decrease in positioning accuracy. Summary of the Invention

[0004] To solve the above technical problems, the first object of the present invention is to propose a multi-tag positioning method based on a variable reception window, which realizes real-time positioning of multiple positioning tags by the base station simultaneously through a variable reception window, adopts a dynamic queue method, reduces the collision probability of positioning tags during air transmission, realizes orderly communication of multiple positioning tags, and does not require cabling construction, with a wide range of application scenarios.

[0005] The second object of the present invention is to propose a multi-tag positioning system based on a variable reception window.

[0006] The technical solution adopted by the present invention is as follows: An embodiment of the present invention proposes a multi-tag positioning method based on a variable reception window, which includes the following steps: The station sends a positioning request to the positioning tag according to the ID (Identity Document) of the positioning tag and records the first transmission time T1. After waiting for the first delay time, it turns on the reception mode, sets the reception window time as the first reception window time according to the ID of the positioning tag; after receiving the positioning request from the station, the positioning tag records the first reception time T2 and adds a set time on the basis of the first delay time according to its own ID, sets it as the second transmission time T3, sends a positioning signal according to T3, switches to the reception mode after the second delay time of sending is completed, and sets the reception window time as the second reception window time; if the station receives the positioning signal within the window period of the first reception window time, it records the ID of the positioning tag and the received timestamp T4, and re-opens the reception window according to the ID of the positioning tag to wait for the positioning signals of other positioning tags. If it times out and the number of successful receptions is not 0, it closes the reception mode and switches to the transmission mode; according to the order of the received positioning signals, the station sequentially sends a positioning reply signal at the third transmission time T5 according to the ID of the positioning tag; if the positioning tag receives the positioning reply signal within the window period of the second reception window time, it records the second reception time T6 and performs verification. After the verification passes, it calculates the distance according to T1, T2, T3, T4, T5, and T6, and performs positioning according to the calculated distance.

[0007] The multi-tag positioning method based on a variable reception window proposed above in the present invention may further have the following additional technical features: According to an embodiment of the present invention, after receiving the positioning request from the station, the positioning tag further includes: verifying the data; after the verification passes, checking whether the station already exists in the exemption list. If it exists, abandon this communication to enable it to communicate with other positioning tags.

[0008] According to an embodiment of the present invention, performing positioning according to the calculated distance further includes: recording the ID of the station of this positioning in the exemption list.

[0009] According to an embodiment of the present invention, the second transmission time is obtained according to the following formula ; where Ubeacon_AT is the actual reception time of the current positioning signal, TAG_DT is the second delay time, Ubeacon_RWT is the first reception window time, and N is a preset value configured according to the actual situation.

[0010] According to an embodiment of the present invention, the distance calculation is specifically performed according to the following formula: ; ; where TOF is the time of flight, Dist is the distance, and c is the speed of light.

[0011] The second aspect embodiment of the present invention proposes a multi-tag positioning system based on a variable reception window, including: a station and positioning tags. Specifically, the station and the positioning tags are used for: the station sends a positioning request to the positioning tag according to the ID of the positioning tag and records the first transmission time T1, opens the reception mode after waiting for the first delay time, and sets the reception window time as the first reception window time according to the ID of the positioning tag; after receiving the positioning request from the station, the positioning tag records the first reception time T2 and adds a set time on the basis of the first delay time according to its own ID, sets it as the second transmission time T3, sends a positioning signal according to T3, switches to the reception mode after the second delay time of sending is completed, and sets the reception window time as the second reception window time; if the station receives the positioning signal within the window period of the first reception window time, records the ID of the positioning tag and the received timestamp T4, and re-opens the reception window according to the ID of the positioning tag to wait for the positioning signals of other positioning tags. If it times out and the number of successful receptions is not 0, then closes the reception mode and switches to the transmission mode; the station sequentially sends positioning reply signals according to the ID of the positioning tag at the third transmission time T5 according to the order of the received positioning signals; if the positioning tag receives the positioning reply signal within the window period of the second reception window time, records the second reception time T6, and performs verification. After the verification passes, calculates the distance according to T1, T2, T3, T4, T5, and T6, and performs positioning according to the calculated distance.

[0012] The above multi-tag positioning system based on a variable reception window of the present invention further has the following additional technical features: According to an embodiment of the present invention, the positioning tag is further used for: after receiving the positioning request from the station, verifying the data; after the verification passes, checking whether the station already exists in the exemption list. If it exists, abandon this communication to enable it to communicate with other positioning tags.

[0013] According to an embodiment of the present invention, the positioning tag is further used for: performing positioning according to the calculated distance and including the ID of the station of this positioning in the exemption list.

[0014] According to an embodiment of the present invention, the station obtains the second transmission time according to the following formula ; where Ubeacon_AT is the actual reception time of the current positioning signal, TAG_DT is the second delay time, Ubeacon_RWT is the first reception window time, and N is a preset value configured according to the actual situation.

[0015] According to an embodiment of the present invention, the positioning tag specifically calculates the distance according to the following formula: ; ; where TOF is the time of flight, Dist is the distance, and c is the speed of light.

[0016] Advantages of the present invention: The present invention realizes real-time positioning of a site with multiple positioning tags simultaneously through a variable receiving window. In terms of the utilization rate of the variable window, a dynamic queue method is adopted, and according to the ID of the positioning tag, it is set into different positioning windows to achieve orderly communication of multiple positioning tags, reduce the collision probability of the positioning tags during air transmission, and does not require wiring construction, being applicable to various environments and scenarios.

[0017] In order to avoid the problem of high-frequency positioning of a certain tag, an exemption list strategy is introduced to control the positioning frequency of the positioning tag. This method greatly improves the positioning success rate and positioning timeliness while reducing power consumption. Description of the drawings

[0018] Figure 1 is a flowchart of a multi-tag positioning method based on a variable receiving window according to an embodiment of the present invention; Figure 2 is a schematic structural diagram of a multi-tag positioning system based on a variable receiving window according to an embodiment of the present invention. Detailed implementation manners

[0019] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0020] Figure 1 is a flowchart of a multi-tag TOF positioning method based on a variable receiving window according to an embodiment of the present invention. As Figure 1 shown, the method includes the following steps: S1, the site sends a positioning request to the positioning tag according to the ID of the positioning tag and records the first sending time T1. After waiting for the first delay time Ubeacon_DT, it turns on the receiving mode and sets the receiving window time as the first receiving window time according to the ID of the positioning tag.

[0021] Specifically, the frequency at which the station sends a positioning request is different from the frequency at which it receives a positioning signal, which can prevent other devices from interfering with the device that is sending a positioning signal when the device sends a positioning request, thus affecting positioning. After sending the positioning request, since the transmission of the signal takes time, the station needs to wait for the first delay time Ubeacon_DT before turning on the receiving mode. Ubeacon_DT is set in advance, and it only needs to control the time window to be long enough to receive the signal, and does not need to be too long. The first receiving window time Ubeacon_RWT is a variable receiving window, which means that the receiving window time set by the station each time can be different. For example, it can be set according to the ID of the positioning tag, and different IDs of the positioning tags are set with different first receiving window times Ubeacon_RWT.

[0022] S2. After receiving the positioning request from the station, the positioning tag records the first receiving time T2, adds a set time on the basis of the first delay time Ubeacon_DT according to its own ID, sets it as the second sending time T3, sends a positioning signal according to T3, and switches to the receiving mode after the second delay time of sending is completed. The set receiving window time is the second receiving window time TAG_RWT. TAG_RWT is set according to the speed of signal transmission.

[0023] Furthermore, after receiving the positioning request from the station, the positioning tag further includes: performing data verification; after the verification passes, checking whether the station already exists in the exemption list. If it exists, this communication is abandoned to enable it to communicate with other positioning tags.

[0024] Specifically, after receiving the positioning request from the station, the positioning tag performs data verification. After the verification passes, it checks whether the station already exists in the exemption list. If it exists, this communication is abandoned and it is allowed to communicate with other positioning tags. If it does not exist, it records the first receiving time T2, sets its own starting identifier according to the preamble bits of the positioning request, and adds a set time on the basis of Ubeacon_DT according to its own ID , and sets this time as the sending time T3 of the positioning signal, that is , to ensure that the sending times of the devices are staggered to avoid mutual interference. After the positioning signal is sent for the second delay time TAG_DT, it switches to the receiving mode, sets the receiving window as the second receiving window time TAG_RW, and waits for the positioning reply signal from the station.

[0025] It can be understood that in the present invention, the frequencies at which the positioning tag receives and sends signals are also different, which can prevent other devices from interfering with the device that is receiving a signal when the device is sending a signal. That is, after the positioning tag switches to the receiving mode, it needs to switch the receiving frequency as well.

[0026] S3. If the station receives a positioning signal during the window period of the first reception window time, record the ID of the positioning tag and the received timestamp T4. According to the ID of the positioning tag, reopen the reception window of the first reception window time to wait for the positioning signals of other positioning tags. If it times out and the number of successful receptions is not 0, then close the reception mode and switch to the transmission mode.

[0027] Specifically, if the station receives a positioning signal of a positioning tag during the window period of Ubeacon_RWT, verify the data. After the data verification passes, record the ID of the positioning tag and the received timestamp T4, and reopen the reception window of Ubeacon_RWT to wait for the positioning signals of other positioning tags. If the station does not receive a positioning signal of a positioning tag during the window period of Ubeacon_RWT, that is, it times out, then the station judges the number of successful receptions of the positioning signal. If the number of successful receptions is 0, the station enters the sleep state, and the sleep time is set to Ubeacon_ST (station sleep time) to reduce power consumption. If the number of successful receptions is not 0, close the reception mode and switch to the transmission mode.

[0028] S4. According to the order of the received positioning signals, the station sequentially sends positioning reply signals according to the ID of the positioning tag at the third transmission time T5.

[0029] Specifically, after the station finishes receiving, it sequentially sends positioning reply signals at the third transmission time T5 according to the order of the received positioning signals.

[0030] In a specific embodiment of the present invention, the second transmission time is obtained according to the following formula ; where Ubeacon_AT is the actual reception time of the current positioning signal, TAG_DT is the second delay time, Ubeacon_RWT is the first reception window time, and N is a preset value configured according to the actual situation (such as device communication delay) to ensure that the receiving device can correctly receive the signal.

[0031] S5. If the positioning tag receives a positioning reply signal during the window period of the second reception window time TAG_RWT, record the second reception time T6 and perform verification. After the verification passes, calculate the distance according to T1, T2, T3, T4, T5, and T6, and perform positioning according to the calculated distance.

[0032] Further, in an embodiment of the present invention, the distance calculation is specifically performed according to the following formula: ; ; where TOF is the time of flight, Dist is the distance, and c is the speed of light.

[0033] In an embodiment of the present invention, after positioning based on the calculated distance, the method further includes: recording the ID of the current positioned site into an exemption list.

[0034] In the present invention, the site integrates a UWB positioning chip and a large-capacity battery and is in a dormant state by default. When the positioning tag sends a positioning activation signal, the positioning chip and the tag are activated for positioning. Since the site is powered by a battery, in large-scale scenarios, no wiring construction is required, which greatly saves the construction cost.

[0035] In summary, according to the multi-tag positioning method based on a variable reception window of the embodiment of the present invention, real-time positioning of a site with multiple positioning tags is achieved through a variable reception window. In terms of the utilization rate of the variable window, a dynamic queue method is adopted, and the IDs of the positioning tags are set into different positioning windows to realize orderly communication of multiple positioning tags, reduce the collision probability of the positioning tags in the air transmission, and no wiring construction is required, which is applicable to various environments and scenarios. To avoid the problem of high-frequency positioning of a certain tag, an exemption list strategy is introduced to control the positioning frequency of the positioning tag. While reducing the power consumption, this method greatly improves the positioning success rate and positioning timeliness.

[0036] Corresponding to the above multi-tag positioning method based on a variable reception window, the present invention also proposes a multi-tag positioning system based on a variable reception window. Since the system embodiment of the present invention corresponds to the above method embodiment, for the details not disclosed in the system embodiment, reference can be made to the above method embodiment, and no further description will be given in the present invention.

[0037] Figure 2 is a schematic structural diagram of a multi-tag positioning system based on a variable reception window according to an embodiment of the present invention, as Figure 2As shown in the figure, the system includes: a station and positioning tags. Among them, the station sends a positioning request to the positioning tag according to the ID of the positioning tag and records the first transmission time T1. After waiting for the first delay time, it turns on the receiving mode and sets the receiving window time as the first receiving window time according to the ID of the positioning tag. After receiving the positioning request from the station, the positioning tag records the first receiving time T2 and adds a set time based on the first delay time according to its own ID, sets it as the second transmission time T3, sends a positioning signal according to T3, switches to the receiving mode after the second delay time of sending is completed, and sets the receiving window time as the second receiving window time. If the station receives a positioning signal within the window period of the first receiving window time, it records the ID of the positioning tag and the received timestamp T4, and re-opens the receiving window according to the ID of the positioning tag to wait for the positioning signals of other positioning tags. If it times out and the number of successful receptions is not 0, it closes the receiving mode and switches to the sending mode. The station sends a positioning reply signal according to the ID of the positioning tag in sequence at the third transmission time T5 according to the order of the received positioning signals. If the positioning tag receives a positioning reply signal within the window period of the second receiving window time, it records the second receiving time T6 and performs verification. After the verification passes, it calculates the distance according to T1, T2, T3, T4, T5, and T6, and performs positioning according to the calculated distance.

[0038] According to an embodiment of the present invention, the positioning tag is further configured to: after receiving the positioning request from the station, perform verification on the data; after the verification passes, check whether the station already exists in the exemption list. If it exists, abandon this communication so that it can communicate with other positioning tags.

[0039] According to an embodiment of the present invention, the positioning tag is further configured to: perform positioning according to the calculated distance and include the ID of the station of this positioning in the exemption list.

[0040] According to an embodiment of the present invention, the station obtains the second transmission time T5 according to the following formula: T5 = Ubeacon_AT is the actual reception time of the current positioning signal, ; where Ubeacon_AT is the actual reception time of the current positioning signal, TAG_DT is the second delay time, Ubeacon_RWT is the first receiving window time, and N is a preset value configured according to the actual situation.

[0041] According to an embodiment of the present invention, the positioning tag specifically calculates the distance according to the following formula: ; ; where TOF is the time of flight, Dist is the distance, and c is the speed of light.

[0042] The multi-tag positioning system based on a variable reception window according to an embodiment of the present invention realizes real-time positioning of a site with multiple positioning tags simultaneously through a variable reception window. In terms of the utilization rate of the variable window, a dynamic queue method is adopted. According to the ID of the positioning tag, it is set into different positioning windows to achieve orderly communication of multiple positioning tags, reduce the collision probability of positioning tags in air transmission, and does not require wiring construction, being applicable to various environments and scenarios. To avoid the problem of high-frequency positioning of a certain tag, an exemption list strategy is introduced to control the positioning frequency of the positioning tag; while reducing power consumption, this method greatly improves the positioning success rate and positioning timeliness.

[0043] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0044] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, "a plurality" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0045] Any process or method description shown in the flowchart or described in other ways herein can be understood as representing a module, segment, or part of code including one or more executable instructions for implementing a customized logical function or process. The scope of the preferred embodiments of the present invention includes additional implementations, where the functions can be executed in a manner that may not be shown or discussed in the order, including in a substantially simultaneous manner or in the reverse order according to the functions involved, which should be understood by those skilled in the art to which the embodiments of the present invention belong.

[0046] The logic and / or steps represented in the flowchart or otherwise described herein can, for example, be considered a definitional sequence list of executable instructions for implementing logical functions, which can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, a system including a processor, or other systems that can fetch and execute instructions from the instruction execution system, apparatus, or device. For the purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by or in connection with the instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of the computer-readable medium include the following: an electrical connection part having one or more wirings (electronic device), a portable computer diskette (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium can even be paper or other suitable medium on which the program can be printed, as the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpretation, or otherwise appropriate processing as necessary, and then storing it in a computer memory.

[0047] It should be understood that various parts of the present invention can be implemented by hardware, software, firmware, or a combination thereof. In the above-described embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or a combination of the following techniques well known in the art can be used: discrete logic circuits having logic gate circuits for implementing logical functions on data signals, application specific integrated circuits having appropriate combinational logic gate circuits, programmable gate arrays (PGAs), field programmable gate arrays (FPGAs), and the like.

[0048] Those of ordinary skill in the art of this technology can understand that all or part of the steps carried by the method of implementing the above embodiments can be completed by a program instructing relevant hardware, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiments.

[0049] In addition, each functional unit in various embodiments of the present invention may be integrated into a processing module, may exist physically alone for each unit, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. When the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0050] The above-mentioned storage medium may be a read-only memory, a magnetic disk, an optical disc, etc. Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A multi-tag positioning method based on a variable receiving window, characterized in that: The following steps are involved: The station sends a positioning request to the positioning tag according to the ID of the positioning tag and records the first sending time T1, turns on the receiving mode after waiting for the first delay time, and sets the receiving window time to the first receiving window time according to the ID of the positioning tag; After receiving the positioning request from the site, the positioning tag records the first receiving time T2 and adds a set time based on its own ID to the first delay time, setting it as the second sending time T3, sends the positioning signal according to T3, switches to the receiving mode after the second delay time is completed, and sets the receiving window time to the second receiving window time; If the station receives the positioning signal within the first receiving window time, it records the positioning tag ID and the receiving timestamp T4, and opens the receiving window again according to the positioning tag ID to wait for the positioning signals of other positioning tags. If the timeout expires and the number of successful receptions is not 0, the receiving mode is closed and switched to the sending mode. The station sends a positioning reply signal at a third sending time T5 according to the ID of the positioning tag in the order of the received positioning signals; If the positioning tag receives a positioning reply signal during the second receiving window time, the second receiving time T6 is recorded and verified. After the verification passes, the distance is calculated according to T1, T2, T3, T4, T5 and T6, and positioning is performed according to the calculated distance.

2. The multi-tag positioning method based on variable receiving window according to claim 1 is characterized in that: After receiving the location request from the site, the location tag also includes: Verify the data; After the verification is passed, check whether the site already exists in the exemption list. If so, abandon the communication so that it can communicate with other positioning tags.

3. The multi-tag positioning method based on variable receiving window according to claim 2 is characterized in that: Positioning based on the calculated distance also includes: The ID of the site being located is included in the exemption list.

4. The multi-tag positioning method based on variable receiving window according to claim 1 is characterized in that: The second sending time T5 is obtained according to the following formula: ； Among them, Ubeacon_AT is the actual receiving time of the current positioning signal, TAG_DT is the second delay time, Ubeacon_RWT is the first receiving window time, and N is the preset value.

5. The multi-tag positioning method based on variable receiving window according to claim 1, characterized in that: The distance is calculated according to the following formula: ； ； Among them, TOF is the flight time, Dist is the distance, and c is the speed of light.

6. A multi-tag positioning system based on a variable receiving window, characterized in that: include: Site and location tags, where site and location tags are specifically used for: The station sends a positioning request to the positioning tag according to the ID of the positioning tag and records the first sending time T1, turns on the receiving mode after waiting for the first delay time, and sets the receiving window time to the first receiving window time according to the ID of the positioning tag; After receiving the positioning request from the site, the positioning tag records the first receiving time T2 and adds a set time based on its own ID to the first delay time, setting it as the second sending time T3, sends the positioning signal according to T3, switches to the receiving mode after the second delay time is completed, and sets the receiving window time to the second receiving window time; If the station receives the positioning signal within the first receiving window time, it records the positioning tag ID and the receiving timestamp T4, and opens the receiving window again according to the positioning tag ID to wait for the positioning signals of other positioning tags. If the timeout expires and the number of successful receptions is not 0, the receiving mode is closed and switched to the sending mode. The station sends a positioning reply signal at a third sending time T5 according to the ID of the positioning tag in the order of the received positioning signals; If the positioning tag receives a positioning reply signal during the second receiving window time, the second receiving time T6 is recorded and verified. After the verification passes, the distance is calculated according to T1, T2, T3, T4, T5 and T6, and positioning is performed according to the calculated distance.

7. The multi-tag positioning system based on variable receiving window according to claim 6, characterized in that: The positioning tag is also used to: After receiving the location request from the site, the location tag verifies the data; After the verification is passed, check whether the site already exists in the exemption list. If so, abandon the communication so that it can communicate with other positioning tags.

8. The multi-tag positioning system based on variable receiving window according to claim 7, characterized in that: The positioning tag is also used to: perform positioning according to the calculated distance, and add the ID of the site positioned this time into the exemption list.

9. The multi-tag positioning system based on variable receiving window according to claim 6, characterized in that: The site obtains the second sending time T5 according to the following formula: ； Among them, Ubeacon_AT is the actual receiving time of the current positioning signal, TAG_DT is the second delay time, Ubeacon_RWT is the first receiving window time, and N is the preset value.

10. The multi-tag positioning system based on variable receiving window according to claim 6, characterized in that: The positioning tag calculates the distance according to the following formula: ； ； Among them, TOF is the flight time, Dist is the distance, and c is the speed of light.

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