Indoor Beidou pseudo satellite positioning system and indoor positioning method

Abstract

The invention relates to an indoor Beidou pseudo satellite positioning system and an indoor positioning method. The indoor Beidou pseudo satellite positioning system comprises a central control module, at least two access modules and an indoor reference station, the access module comprises a Beidou signal generation unit and a wireless communication unit; the central control module is used for generating a control instruction when the user terminal is positioned, and sending the control instruction to each access module; the access module is used for generating a Beidou signal through a Beidou signal generation unit according to the control instruction and sending the Beidou signal to the user terminal and the indoor reference station; the indoor reference station is used for carrying out differential processing on the Beidou signal, generating a reference signal and sending the reference signal to the central control module; the central control module is also used for forwarding the reference signal to each access module; and the access module is also used for sending the reference signal to the user terminal through the wireless communication unit so as to indicate the user terminal to carry out positioning according to the Beidou signal and the reference signal. And high-precision positioning of indoor signals is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of indoor positioning technology, in particular to an indoor Beidou pseudolite positioning system and an indoor positioning method. BACKGROUND

[0002] Due to the walls and floors of buildings, the weak satellite signals are severely attenuated and reflected, resulting in that the terminal cannot receive a sufficient number of satellite signals for triangulation positioning, and the satellite positioning system is almost ineffective in the indoor space. With the acceleration of social digitization and intelligentization, the precise perception and management of people, things and events in the indoor space have become increasingly urgent.

[0003] The traditional indoor positioning adopts Wi-Fi / Bluetooth positioning technology, that is, low-power Bluetooth beacons are uniformly deployed in the indoor space, and the device measures the received signal strength to estimate the distance between the device and multiple beacons by using a signal attenuation model, and then calculates the position by using the trilateration method.

[0004] However, the positioning accuracy of this positioning method is low. SUMMARY

[0005] Therefore, it is necessary to provide an indoor Beidou pseudolite positioning system and an indoor positioning method capable of improving the indoor positioning accuracy.

[0006] In a first aspect, the present application provides an indoor Beidou pseudolite positioning system, comprising a central control module, at least two access modules and an indoor reference station; the access module comprises a Beidou signal generation unit and a wireless communication unit; the central control module is connected with each of the access modules and the indoor reference station, and the indoor reference station is connected with each of the access modules;

[0007] The central control module is configured to generate a control instruction when positioning a user terminal, and send the control instruction to each of the access modules;

[0008] The access module is configured to generate a Beidou signal by the Beidou signal generation unit according to the control instruction, and send the Beidou signal to the user terminal and the indoor reference station;

[0009] The indoor reference station is configured to perform differential processing on the Beidou signal, generate a reference signal, and send the reference signal to the central control module;

[0010] The central control module is further configured to forward the reference signal to each of the access modules;

[0011] The access module is further configured to send the reference signal to the user terminal through the wireless communication unit, so as to instruct the user terminal to perform positioning according to the Beidou signal and the reference signal.

[0012] In one of the embodiments, the access module further comprises a radio frequency switch and a Beidou frequency band antenna, the input end of the Beidou signal generation unit is connected with the central control module, the output end of the Beidou signal generation unit is connected with the input end of the radio frequency switch, and the output end of the radio frequency switch is connected with the Beidou frequency band antenna.

[0013] The Beidou signal generation unit is configured to generate a Beidou signal conforming to the Beidou satellite navigation system standard.

[0014] The radio frequency switch is configured to switch the frequency band of the Beidou signal to a target frequency band.

[0015] The Beidou frequency band antenna is configured to transmit the Beidou signal to the user terminal based on the target frequency band.

[0016] In one of the embodiments, the central control module comprises a central control server and a clock source, and the central control server is connected with the clock source.

[0017] The clock source is configured to set a unified time reference for indoor positioning.

[0018] The central control server is configured to generate a control instruction based on the unified time reference when positioning the user terminal, and send the control instruction to each of the access modules.

[0019] In one of the embodiments, the clock source is a GNSS disciplined clock.

[0020] In one of the embodiments, the wireless communication unit is a Wi-Fi communication unit.

[0021] In one of the embodiments, the central control module and each of the access modules communicate based on the PTP protocol.

[0022] In a second aspect, the present application further provides an indoor positioning method applied to the central control module of the indoor Beidou pseudolite positioning system, and the method comprises:

[0023] When positioning the user terminal, a control instruction is generated and sent to each of the access modules in the indoor Beidou pseudolite positioning system, so as to instruct the access modules to generate a Beidou signal according to the control instruction; the Beidou signal is used to instruct the user terminal to perform positioning according to the Beidou signal.

[0024] receiving a reference signal sent by an indoor reference station in the indoor Beidou pseudolite positioning system, and sending the reference signal to each of the access modules, so as to instruct the access modules to forward the reference signal to user terminals; the reference signal is used to instruct the user terminals to perform positioning according to the reference signal and in combination with the Beidou signals.

[0025] In one of the embodiments, before the control instruction is generated, the method further comprises:

[0026] obtaining position coordinates and signal transmission delay parameters of each of the access modules, and position coordinates of the indoor reference station;

[0027] calculating signal transmission offsets of each of the access modules according to the position coordinates of each of the access modules and the position coordinates of the indoor reference station;

[0028] determining signal transmission timestamps of each of the access modules according to the signal transmission offsets of each of the access modules and the signal transmission delay parameters of each of the access modules, and transmitting the signal transmission timestamps to the access modules; the signal transmission timestamps are used to instruct the access modules to transmit the Beidou signals based on the pre-calculated signal transmission timestamps.

[0029] In one of the embodiments, the calculation of the signal transmission offsets of each of the access modules according to the position coordinates of each of the access modules and the position coordinates of the indoor reference station comprises:

[0030] determining signal propagation durations of each of the access modules to the indoor reference station according to the position coordinates of each of the access modules and the position coordinates of the indoor reference station;

[0031] determining a target access module in all the access modules, and determining the signal transmission offsets of each of the access modules according to the signal propagation duration of the target access module and the signal propagation durations of each of the access modules to the indoor reference station.

[0032] In one of the embodiments, the determination of the signal transmission timestamps of each of the access modules according to the signal transmission offsets of each of the access modules and the signal transmission delay parameters of each of the access modules comprises:

[0033] obtaining a unified time reference set by the clock source, and performing summation operation on the unified time reference and the signal transmission offsets of each of the access modules respectively to obtain initial signal transmission timestamps of each of the access modules;

[0034] performing subtraction operation on the initial signal transmission timestamps of each of the access modules and the signal transmission delay parameters of the access modules to obtain the signal transmission timestamps of the access modules.

[0035] The indoor Beidou pseudolite positioning system and the indoor positioning method, comprising: a central control module, at least two access modules and an indoor reference station; the access module comprises a Beidou signal generation unit and a wireless communication unit; the central control module is connected with each access module and the indoor reference station respectively, and the indoor reference station is connected with each access module respectively; the central control module is used for generating a control instruction when positioning a user terminal, and sending the control instruction to each access module; the access module is used for generating a Beidou signal according to the control instruction by the Beidou signal generation unit, and sending the Beidou signal to the user terminal and the indoor reference station; the indoor reference station is used for differentially processing the Beidou signal, generating a reference signal, and sending the reference signal to the central control module; the central control module is further used for forwarding the reference signal to each access module; the access module is further used for sending the reference signal to the user terminal by the wireless communication unit, so as to instruct the user terminal to position according to the Beidou signal and the reference signal. By integrating the Beidou signal generation unit and the wireless communication unit in each access module and controlling by the central control module, on the one hand, the Beidou signal generation unit generates a compliant Beidou signal which can be directly received by the user terminal, and on the other hand, the wireless communication unit transmits the reference signal, that is, the differential correction data, which solves the terminal compatibility and signal compliance problem, realizes the centimeter-level positioning accuracy in the indoor environment, at the same time, the central control module calculates the signal transmission time stamp of each access module, that is, the control instruction, according to the self-coordinate of each access module and the position coordinate of the indoor reference station, the central control module issues the control instruction to each access module, so that all access modules transmit signals at different time points, ensuring that all signals are synchronized in the current indoor area, that is, "air interface alignment", which realizes the nanosecond-level effective synchronization at a low cost, and provides a data basis for the high-precision positioning of the subsequent positioning terminal. Compared with the low positioning accuracy of the traditional Bluetooth positioning method, the indoor Beidou pseudolite positioning system realizes the high-precision positioning of the indoor signal by integrating the Beidou generation unit and the wireless communication unit. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related art, the following will briefly introduce the drawings needed to be used in the description of the embodiments of the present application or the related art. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other related drawings can also be obtained without creative labor.

[0037] Figure 1 The structural block diagram of the indoor Beidou pseudolite positioning system in an embodiment;

[0038] Figure 2A structural block diagram of an access module of an indoor Beidou pseudolite positioning system in one embodiment;

[0039] Figure 3 A structural block diagram of an indoor Beidou pseudolite positioning system in another embodiment;

[0040] Figure 4 A flowchart of an indoor positioning method in one embodiment;

[0041] Figure 5 A flowchart of sending a signal transmission timestamp in one embodiment;

[0042] Figure 6 A flowchart of calculating a signal transmission offset of an access module in one embodiment;

[0043] Figure 7 A flowchart of determining a signal transmission timestamp in one embodiment. DETAILED DESCRIPTION

[0044] In order to facilitate the understanding of the present application, a more comprehensive description of the present application will be made below with reference to the relevant drawings. The embodiments of the present application are shown in the drawings. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used in the specification of the present application are only for the purpose of describing specific embodiments of the present application and are not intended to limit the present application.

[0046] It can be understood that the terms "first", "second" and the like used in the present application can be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from another element. For example, without departing from the scope of the present application, the first resistor can be referred to as the second resistor, and similarly, the second resistor can be referred to as the first resistor. The first resistor and the second resistor are both resistors, but they are not the same resistor.

[0047] It can be understood that "connection" in the following embodiments, if the circuits, modules, units and the like connected to each other have the transmission of electrical signals or data, should be understood as "electrical connection", "communication connection" and the like.

[0048] It can be understood that "at least one" means one or more, and "multiple" means two or more. "At least part of the element" means part or all of the element.

[0049] When used herein, the singular forms of “a,” “an,” and “ / the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0050] Because building walls and floors severely attenuate and reflect weak satellite signals, terminals cannot receive enough satellite signals for triangulation, rendering satellite positioning systems virtually ineffective indoors. With the accelerating digitalization and intelligentization of society, the need for accurate perception and management of people, objects, and events in indoor spaces is becoming increasingly urgent. Traditional indoor positioning uses Wi-Fi / Bluetooth positioning technology, which involves uniformly deploying low-power Bluetooth beacons indoors. Devices measure the received signal strength, estimate the distance to multiple beacons using a signal attenuation model, and then calculate the location using trilateration. However, this positioning method has low accuracy.

[0051] In view of the above-mentioned technical problems, this application provides an indoor BeiDou pseudo-satellite positioning system to improve indoor positioning accuracy. The following embodiments will specifically describe the indoor BeiDou pseudo-satellite positioning system.

[0052] In one exemplary embodiment, such as Figure 1 As shown, the indoor BeiDou pseudo-satellite positioning system includes: a central control module, at least two access modules, and an indoor reference station; the access modules include a BeiDou signal generation unit and a wireless communication unit; the central control module is connected to each access module and the indoor reference station respectively, and the indoor reference station is connected to each access module respectively.

[0053] The central control module is used to generate control commands when locating user terminals and send the control commands to each access module.

[0054] The access module is used to generate BeiDou signals according to control commands through the BeiDou signal generation unit, and send the BeiDou signals to the user terminal and indoor reference station;

[0055] The indoor reference station is used to perform differential processing on BeiDou signals, generate reference signals, and send the reference signals to the central control module.

[0056] The central control module is also used to forward reference signals to each access module;

[0057] The access module is further configured to send the reference signal to the user terminal through the wireless communication unit to instruct the user terminal to perform positioning according to the Beidou signal and the reference signal.

[0058] The access module can be deployed in an array or at preset intervals when deployed indoors, and the position coordinates of the access module are fixed after deployment. The access module can transmit its position coordinates to the central control module for subsequent processing after deployment. The access module can also transmit its position coordinates to the central control module after receiving an instruction from the central control module to obtain the position coordinates when the central control module is positioning the user terminal.

[0059] Optionally, the Beidou signal generation unit can be any one of a high-precision Beidou positioning chip, an Internet of Things / special-purpose chip, or a baseband radio frequency integrated chip, such as UC9810 and UC9820 of Chipstar, TD1030 of Taidu Microelectronics, and ZX2971 of ZTE Microelectronics. It can also be other chips that can generate Beidou signals, and the present disclosure is not limited in this regard. The wireless communication unit is configured to establish a wireless data transmission link and can be any one of Wi-Fi, WAPI, Bluetooth, Zigbee, Z-Wave, Thread, UWB, and NFC. It can be other types of wireless communication units, and the present disclosure is not limited in this regard.

[0060] Optionally, the indoor reference station can be any one of a pseudolite indoor reference station, a carrier phase differential indoor reference station, a fusion indoor reference station, or a simplified indoor reference station. It can also be other reference stations that can correct the output of the Beidou signal of the access module, and the present disclosure is not limited in this regard. The number of indoor reference stations can be one or more. The reference signal can be a differential correction signal.

[0061] Optionally, the control instruction can include the time at which the access module generates and sends the Beidou information. The control instructions received by each access module are different. The central control module can send the control instructions to each access module at the same time, in order of increasing distance from the central control module, or by region, and the present disclosure is not limited in this regard.

[0062] In the embodiments of the present application, when positioning a certain indoor area is needed, the number of access modules is determined according to the area of the indoor area. Alternatively, a mapping table of indoor area and access module number is traversed, and the larger the indoor area, the more access modules. Compare the indoor area with the preset area interval in the mapping table to determine the number of access modules corresponding to the preset area interval where the indoor area is located as the number of access modules required for the current indoor area. Obtain the corresponding number of access modules and an indoor reference station, and deploy the access modules and the indoor reference station in the current indoor area according to the preset deployment mode (array or interval). And the central control module is connected with each access module and indoor reference station through Ethernet. After the indoor Beidou pseudolite positioning system is configured, the central control module first controls each access module to send a measurement signal to the indoor reference station at a unified time reference, that is, the measurement signal is generated from the Beidou signal generation unit of the access module, and passes through the internal circuit, the radio frequency switch, the filter, and finally reaches the antenna port, which is transmitted to the indoor reference station by the antenna port. The measurement signal has a fixed time delay when it is transmitted from the Beidou signal generation unit of the access module to the antenna port, that is, the signal transmission delay parameter. The Beidou signal time received by the indoor reference station determines the signal transmission delay parameter of each access module. This delay is the inherent time of the access module hardware, and the signal transmission delay parameter of each access module needs to be calibrated separately. Based on the signal transmission delay parameter of each access module and the position coordinates of each access module and the position coordinates of the reference station, the signal transmission timestamp of each access module is calculated, and the control instruction for each access module is generated based on the signal transmission timestamp. The control instruction is sent to each access module. When the user terminal enters the current indoor area, each access module generates a Beidou signal at the signal transmission timestamp corresponding to the control instruction through the Beidou signal generation unit, and sends the Beidou signal to the user terminal and the indoor reference station; the indoor reference station differentially processes the Beidou signal to generate a reference signal, and sends the reference signal to the central control module; the central control module forwards the reference signal to each access module; the access module sends the reference signal to the user terminal through the wireless communication unit, and the user terminal fuses the Beidou signal and the reference signal through the RTK algorithm to obtain the position coordinates of the user terminal itself.

[0063] The aforementioned indoor BeiDou pseudosatellite positioning system includes: a central control module, at least two access modules, and an indoor reference station; each access module includes a BeiDou signal generation unit and a wireless communication unit; the central control module is connected to each access module and the indoor reference station, and the indoor reference station is connected to each access module; the central control module generates control commands and sends them to each access module when locating a user terminal; each access module generates a BeiDou signal based on the control commands through the BeiDou signal generation unit and sends it to the user terminal and the indoor reference station; the indoor reference station performs differential processing on the BeiDou signal to generate a reference signal and sends it to the central control module; the central control module also forwards the reference signal to each access module; and each access module sends the reference signal to the user terminal via the wireless communication unit to instruct the user terminal to locate itself based on the BeiDou signal and the reference signal. By integrating the BeiDou signal generation unit and the wireless communication unit into each access module and controlling them through a central control module, the system generates compliant BeiDou signals that can be directly received by user terminals based on the BeiDou signal generation unit. On the other hand, it transmits reference signals, i.e., differential correction data, based on the wireless communication unit. This solves the problems of terminal compatibility and signal compliance, achieving centimeter-level positioning accuracy in indoor environments. Simultaneously, the central control module calculates the signal transmission timestamp of each access module based on its own coordinates and the position coordinates of the indoor reference station, i.e., the control command. The central control module issues control commands to each access module, causing all access modules to transmit signals at different times, ensuring that all signals are synchronized in the current indoor area, i.e., "air interface alignment". This achieves nanosecond-level effective synchronization at a low cost, providing a data foundation for high-precision positioning of subsequent positioning terminals. Compared with the low positioning accuracy of traditional Bluetooth positioning methods, the above-mentioned indoor BeiDou pseudo-satellite positioning system achieves high-precision positioning of indoor signals by integrating the BeiDou generation unit and the wireless communication unit.

[0064] In one exemplary embodiment, such as Figure 2 As shown, the access module also includes an RF switching switch and a BeiDou band antenna. The input end of the BeiDou signal generation unit is connected to the central control module, the output end of the BeiDou signal generation unit is connected to the input end of the RF switching switch, and the output end of the RF switching switch is connected to the BeiDou band antenna.

[0065] The BeiDou signal generation unit is used to generate BeiDou signals that conform to the BeiDou satellite navigation system standards.

[0066] Radio frequency switching switch is used to switch the frequency band of BeiDou signals to the target frequency band;

[0067] BeiDou band antennas are used to transmit BeiDou signals to user terminals based on the target frequency band.

[0068] The radio frequency switch can be any one of a PIN diode switch, a GaAs pHEMT / FET switch, a SOI / CMOS switch, or other types of radio frequency switches, which are not limited herein. The Beidou band antenna can be any one of a ceramic patch antenna, a spiral antenna, a microstrip antenna, a four-arm spiral antenna, or a choke loop antenna / measuring antenna, or other types of dual-frequency antennas, which are not limited herein. The target frequency band can be B1C, or other frequency bands, which are not limited herein.

[0069] In the embodiments of the present application, when the positioning terminal enters the current indoor area, a positioning request is sent to each access module. Based on the positioning request, the Beidou signal generation unit in each access module generates a high-level switching signal, i.e., a Beidou signal, and transmits the Beidou signal to the control pin of the radio frequency switch. The radio frequency switch switches the Beidou band antenna from the frequency band of the Beidou signal to the target frequency band within a preset time. The Beidou band antenna transmits the Beidou signal to the positioning terminal based on the target frequency band. After the transmission is completed, the radio frequency switch switches the frequency band of the Beidou signal from the target frequency band to the default frequency band of the Beidou signal, avoiding affecting the normal transmission of subsequent Beidou signals.

[0070] The above system ensures the stable transmission of the Beidou signal by setting the radio frequency switch and the Beidou band antenna, further realizing the accuracy of indoor positioning.

[0071] In an exemplary embodiment, as shown in Figure 3 The central control module includes a central master server and a clock source. The central master server is connected to the clock source.

[0072] The clock source is used to set a unified time reference for indoor positioning.

[0073] The central master server is used to generate a control instruction based on the unified time reference when positioning the user terminal, and send the control instruction to each access module.

[0074] The clock source can be any one of a GNSS disciplined clock, a GNSS receiver / time service module, an OCXO, a hydrogen atomic clock, a cesium atomic clock, a rubidium atomic clock, or other types of high-precision clock sources, which are not limited herein. The unified time reference can be any time when the user terminal needs to be positioned after entering the indoor area, which is not limited herein. That is, the unified time reference can be one time or multiple times.

[0075] Optionally, the central master server can be any one of a physical server, a virtual server, a cloud server, an edge server, or other servers capable of data processing, which are not limited herein.

[0076] In the embodiments of the present application, after the indoor Beidou pseudolite positioning system is configured, a uniform time reference required for positioning is set by using a clock source, the central control module controls each access module to send a Beidou signal to the indoor reference station at the uniform time reference, the hardware signal transmission delay parameter of each access module is determined by the time of the Beidou signal received by the indoor reference station, and the signal transmission timestamp of each access module is calculated in combination with the position coordinates of each access module and the position coordinates of the reference station. The control instruction for each access module is generated based on the signal transmission timestamp, and the control instruction is sent to each access module.

[0077] The indoor Beidou pseudolite positioning system sets a clock source to provide a uniform time and frequency reference for the entire indoor Beidou pseudolite positioning system. The central control module calculates the signal transmission timestamp of each access module, i.e., the control instruction, according to the uniform time reference, the coordinates of each access module, and the position coordinates of the indoor reference station. The central control module sends the control instruction to each access module, so that all access modules transmit signals at different time points, ensuring that all signals are synchronized in the current indoor area, i.e., "air interface alignment", and achieving nanosecond-level effective synchronization at a low cost, thereby providing a data basis for subsequent high-precision positioning of the terminal.

[0078] In some embodiments, the central control module and each access module communicate based on the PTP protocol.

[0079] The PTP protocol can be the IEEE 1588 PTP protocol or other types of wired Ethernet protocols, which are not limited herein.

[0080] The central control module of the indoor Beidou pseudolite positioning system provides nanosecond to sub-microsecond time synchronization for all access modules through the wired Ethernet running the PTP precise time protocol, thereby improving the accuracy of indoor positioning.

[0081] In an exemplary embodiment, as shown in Figure 4 Based on any of the above-mentioned indoor Beidou pseudolite positioning systems, the present application further provides an indoor positioning method applied to the central control module of the indoor Beidou pseudolite positioning system, which comprises the following steps:

[0082] S401, when positioning the user terminal, generating a control instruction and sending the control instruction to each access module in the indoor Beidou pseudolite positioning system to instruct the access module to generate a Beidou signal according to the control instruction.

[0083] The Beidou signal is used to instruct the user terminal to perform positioning according to the Beidou signal.

[0084] In the embodiments of the present application, when positioning a certain indoor area is needed, the access module and the indoor reference station are configured according to the indoor layout. The central control module is connected with each access module and indoor reference station through Ethernet. After the indoor Beidou pseudolite positioning system is configured, the central control module controls each access module to send a Beidou signal to the indoor reference station at a unified time reference. The signal transmission delay parameters of each access module are determined by the Beidou signal time received by the indoor reference station. The signal transmission time stamp of each access module is calculated by combining the position coordinates of each access module and the position coordinates of the reference station. The control instruction for each access module is generated based on the signal transmission time stamp, and the control instruction is sent to each access module.

[0085] S402, receiving a reference signal sent by an indoor reference station in an indoor Beidou pseudolite positioning system, and sending the reference signal to each access module to instruct the access module to forward the reference signal to the user terminal.

[0086] The reference signal is used to instruct the user terminal to perform positioning according to the reference signal and in combination with the Beidou signal.

[0087] In the embodiments of the present application, when the user terminal enters the current indoor area, each access module generates a Beidou signal at the signal transmission time stamp corresponding to the control instruction by the Beidou signal generation unit, and sends the Beidou signal to the user terminal and the indoor reference station. The indoor reference station compares its known accurate position with the position of the access module carried by the Beidou signal, calculates the common error correction value including the carrier phase correction, the pseudo-range correction, the "air interface alignment" residual error, the clock difference and the atmospheric residual error, i.e. the reference signal, and sends the reference signal to the central control module. The central control module forwards the reference signal to each access module. The access module sends the reference signal to the user terminal through the wireless communication unit. The user terminal fuses and processes the Beidou signal and the reference signal by using the RTK algorithm or the VRS algorithm to obtain the position coordinates of the user terminal itself.

[0088] The above method solves the terminal compatibility and signal compliance problems by integrating the Beidou signal generation unit and the wireless communication unit in each access module and controlling through the central control module. On the one hand, the Beidou signal generation unit generates a compliant Beidou signal that can be directly received by the user terminal. On the other hand, the wireless communication unit transmits the reference signal, i.e., the differential correction data. The method realizes centimeter-level positioning accuracy in an indoor environment. At the same time, the central control module calculates the signal transmission timestamp, i.e., the control instruction, of each access module based on the self-coordinate of each access module and the position coordinate of the indoor reference station. The central control module issues the control instruction to each access module, so that all access modules transmit signals at different time points, ensuring that all signals in the current indoor area are synchronized, i.e., "air interface alignment". The above indoor Beidou pseudolite positioning system realizes nanosecond-level effective synchronization at a low cost, provides a data basis for subsequent high-precision positioning of the positioning terminal, and solves the problem of low positioning accuracy of the traditional Bluetooth positioning method. By integrating the Beidou generation unit and the wireless communication unit, the above indoor Beidou pseudolite positioning system realizes high-precision positioning of indoor signals.

[0089] In one exemplary embodiment, as shown in FIG. 1, before generating the control instruction, the method further includes: Figure 5

[0090] S501, obtaining the position coordinates and signal transmission delay parameters of each access module, and the position coordinates of the indoor reference station.

[0091] The signal transmission delay parameter can be the fixed time delay of the measured signal from the Beidou signal generation unit of the access module, through the internal circuit, the radio frequency switch, and the filter, to finally reach the antenna port. This delay is the inherent time of the access module hardware, which needs to be calibrated for each access module separately.

[0092] ​In the embodiments of the present application, after the indoor Beidou pseudolite positioning system is configured, a unified time reference is set by using a clock source, the central control module can obtain the position coordinates of each access module and indoor reference station through the position information uploaded by each access module and indoor reference station in advance, and can also call the position coordinates of each access module and indoor reference station from each access module and indoor reference station in real time. When obtaining the signal transmission delay parameters of each access module, the central control module can control each access module to send a Beidou signal to the indoor reference station at a unified time reference, and the hardware signal transmission delay parameters of each access module can be determined by the time of the Beidou signal received by the indoor reference station, that is, the distance between each access module and the indoor reference station is determined based on the position coordinates of each access module and the indoor reference station, and the distance between each access module and the indoor reference station is divided by the speed of light to obtain the standard time length of the Beidou signal sent by each access module to reach the indoor reference station, and the standard time of the Beidou signal sent by each access module to reach the indoor reference station is obtained based on the standard time length and the unified time reference, and the signal transmission delay parameters of each access module are obtained by subtracting the time of the Beidou signal received by the indoor reference station from the standard time of the Beidou signal sent by each access module to reach the indoor reference station.

[0093] S502, the signal transmission offset of each access module is calculated according to the position coordinates of the access module and the position coordinates of the indoor reference station.

[0094] In the embodiments of the present application, after the central control module obtains the position coordinates and signal transmission delay parameters of the access module, and the position coordinates of the indoor reference station, the signal propagation time length of each access module to the indoor reference station is determined according to the position coordinates of each access module and the position coordinates of the indoor reference station; a target access module in all access modules is determined, and the signal transmission offset of each access module is determined according to the signal propagation time length of the target access module and the signal propagation time length of each access module to the indoor reference station.

[0095] S503, the signal transmission time stamp of each access module is determined according to the signal transmission offset of each access module and the signal transmission delay parameter of each access module, and the signal transmission time stamp is transmitted to the access module.

[0096] The signal transmission time stamp is used to indicate that the access module transmits the Beidou signal according to the pre-calculated signal transmission time stamp.

[0097] In the embodiments of the present application, the unified time reference set by the clock source is obtained, the unified time reference and the signal transmission offset of each access module are summed to obtain the initial signal transmission time stamp of each access module, and the initial signal transmission time stamp of each access module is subtracted from the signal transmission delay parameter of the access module to obtain the signal transmission time stamp of the access module.

[0098] In an example embodiment, as shown in Figure 6 According to the position coordinates of the access modules and the position coordinates of the indoor reference station, the signal transmission offset of each access module is calculated, including:

[0099] S601, according to the position coordinates of each access module and the position coordinates of the indoor reference station, the signal propagation time of each access module to the indoor reference station is determined.

[0100] In an embodiment of the application, the signal propagation time of each access module to the indoor reference station can be represented by the following relationship (1):

[0101] (1) ;

[0102] Wherein, is the signal propagation time of the i-th access module to the indoor reference station, is the position coordinates of the i-th access module, is the position coordinates of the indoor reference station, and c is the speed of light.

[0103] S602, determine the target access module in all access modules, according to the signal propagation time of the target access module and determine the signal propagation time of each access module to the indoor reference station to determine the signal transmission offset of each access module.

[0104] Wherein, the target access module is the access module farthest from the indoor reference station.

[0105] In an embodiment of the application, in order to make all signals arrive at the indoor reference station at the same time, the access module farthest from the indoor reference station needs to be transmitted in advance, and the access module close to the indoor reference station needs to be transmitted later. The central control module selects the farthest access module as the reference to calculate the signal propagation time of each access module to the indoor reference station. The signal transmission offset of each access module to the indoor reference station can be represented by the following relationship (2):

[0106] (2) ;

[0107] Wherein, is the signal propagation time of the i-th access module to the indoor reference station, is the signal propagation time of the farthest access module to the indoor reference station, is the signal transmission offset of the i-th access module.

[0108] In an example embodiment, as shown in Figure 7 According to the signal transmission offset of each access module and the signal transmission delay parameter of each access module, the signal transmission timestamp of each access module is determined, including:

[0109] S701, obtaining a unified time reference set by a clock source, and performing summation operation on the unified time reference and a signal transmission offset of each access module to obtain an initial signal transmission timestamp of each access module;

[0110] S702, performing subtraction operation on the initial signal transmission timestamp of each access module and a signal transmission delay parameter of the access module to obtain a signal transmission timestamp of the access module.

[0111] In the embodiment of the application, the signal transmission timestamp of each access module can be represented by the following relation (3):

[0112] (3) ;

[0113] wherein, the unified time reference is, the signal transmission offset of the i th access module is, the signal transmission delay parameter of the access module is, the initial signal transmission timestamp of the i th access module is.

[0114] By calculating the signal transmission timestamp of the access module, it can be ensured that the Beidou signals of each access module are transmitted according to the corresponding time, and the precision of indoor positioning is improved.

[0115] Optionally, the method further comprises:

[0116] When it is monitored that the actual signal transmission time of the access module is not the same as the signal transmission timestamp, the signal transmission timestamp of the access module needs to be recalibrated, that is, the current position coordinates of the access module, the signal transmission delay parameter and the position coordinates of the indoor reference station are determined, the signal propagation time length from the access module to the indoor reference station is determined according to the position coordinates of the access module and the position coordinates of the indoor reference station; a target access module in all access modules is determined, and the signal transmission offset of each access module is determined according to the signal propagation time length of the target access module and the signal propagation time length from the access module to the indoor reference station. After obtaining the current time of the clock source, the earliest unified time reference is obtained, summation operation is performed on the unified time reference and the signal transmission offset of the access module to obtain the initial signal transmission timestamp of the access module; subtraction operation is performed on the initial signal transmission timestamp of the access module and the signal transmission delay parameter of the access module to obtain the signal transmission timestamp of the access module, and a new control instruction is generated and sent to the access module to instruct the access module to generate and transmit the Beidou signal at the time corresponding to the new control instruction.

[0117] When an abnormal offset of an access module is monitored, the central control module can automatically calculate and update the transmission time offset parameter, realizing online self-calibration and long-term stable operation of the indoor Beidou pseudolite positioning system.

[0118] In the description of the specification, the description referring to the terms "some embodiments", "other embodiments", and the like means that the particular feature, structure, material, or characteristic being described is included in at least one embodiment or example of the application. The illustrative description does not imply that all embodiments or examples of the application include the particular feature, structure, material, or characteristic.

[0119] The technical features of the above embodiments can be combined in any manner, and for the sake of brevity, not all possible combinations of the technical features in the above embodiments are described, but as long as the combinations of the technical features do not contradict each other, they should be considered within the scope of the present application.

[0120] The above embodiments only express several implementation manners of the application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the scope of the application. It should be pointed out that for those skilled in the art, some modifications and improvements can be made without departing from the concept of the application, and these all belong to the protection scope of the application. Therefore, the protection scope of the application should be subject to the appended claims.

Claims

1. An indoor BeiDou pseudo-satellite positioning system, characterized in that, The indoor BeiDou pseudo-satellite positioning system includes: a central control module, at least two access modules, and an indoor reference station; each access module includes a BeiDou signal generation unit and a wireless communication unit; the central control module is connected to each of the access modules and the indoor reference station, and the indoor reference station is connected to each of the access modules. The central control module is used to generate control commands when locating user terminals and send the control commands to each of the access modules. The access module is used to generate a BeiDou signal according to the control command through the BeiDou signal generation unit, and send the BeiDou signal to the user terminal and the indoor reference station; The indoor reference station is used to perform differential processing on the BeiDou signal, generate a reference signal, and send the reference signal to the central control module. The central control module is also used to forward the reference signal to each of the access modules; The access module is further configured to transmit the reference signal to the user terminal through the wireless communication unit, so as to instruct the user terminal to perform positioning based on the BeiDou signal and the reference signal.

2. The indoor BeiDou pseudo-satellite positioning system according to claim 1, characterized in that, The access module also includes an RF switching switch and a BeiDou band antenna. The input terminal of the BeiDou signal generation unit is connected to the central control module, the output terminal of the BeiDou signal generation unit is connected to the input terminal of the RF switching switch, and the output terminal of the RF switching switch is connected to the BeiDou band antenna. The BeiDou signal generation unit is used to generate BeiDou signals that conform to the BeiDou satellite navigation system standard; The radio frequency switching switch is used to switch the frequency band of the BeiDou signal to the target frequency band; The BeiDou frequency band antenna is used to transmit the BeiDou signal to the user terminal based on the target frequency band.

3. The indoor BeiDou pseudo-satellite positioning system according to claim 1, characterized in that, The central control module includes a central main control server and a clock source, and the central main control server is connected to the clock source. The clock source is used to set a unified time reference for indoor positioning; The central control server is used to generate control commands when locating user terminals based on the unified time reference, and send the control commands to each of the access modules.

4. The indoor BeiDou pseudo-satellite positioning system according to claim 3, characterized in that, The clock source is a GNSS disciplined clock.

5. The indoor BeiDou pseudo-satellite positioning system according to claim 1, characterized in that, The wireless communication unit is a Wi-Fi communication unit.

6. The indoor BeiDou pseudo-satellite positioning system according to claim 1, characterized in that, The central control module communicates with each of the access modules based on the PTP protocol.

7. An indoor positioning method, characterized in that, The method, applied to the central control module of the indoor BeiDou pseudosatellite positioning system as described in any one of claims 1-6, comprises: When locating a user terminal, a control command is generated and sent to each of the access modules in the indoor BeiDou pseudo-satellite positioning system to instruct the access modules to generate a BeiDou signal according to the control command; the BeiDou signal is used to instruct the user terminal to locate itself according to the BeiDou signal. The system receives reference signals sent by indoor reference stations in the indoor BeiDou pseudo-satellite positioning system and sends the reference signals to each of the access modules to instruct the access modules to forward the reference signals to the user terminals; the reference signals are used to instruct the user terminals to perform positioning based on the reference signals and in combination with the BeiDou signals.

8. The indoor positioning method according to claim 7, characterized in that, Before generating control commands, the method further includes: Obtain the location coordinates and signal transmission delay parameters of each access module, and the location coordinates of the indoor reference station; The signal transmission offset of each access module is calculated based on the location coordinates of the access module and the location coordinates of the indoor reference station. The signal transmission timestamp of each access module is determined based on the signal transmission offset and signal transmission delay parameters of each access module, and the signal transmission timestamp is transmitted to the access module; the signal transmission timestamp is used to instruct the access module to transmit the BeiDou signal according to the pre-calculated signal transmission timestamp.

9. The indoor positioning method according to claim 8, characterized in that, Based on the location coordinates of the access module and the location coordinates of the indoor reference station, the signal transmission offset of each access module is calculated, including: The signal propagation time from each access module to the indoor reference station is determined based on the location coordinates of each access module and the location coordinates of the indoor reference station. Identify the target access module among all access modules, and determine the signal transmission offset of each access module based on the signal propagation time of the target access module and the signal propagation time from each access module to the indoor reference station.

10. The indoor positioning method according to claim 8, characterized in that, The signal transmission timestamp of each access module is determined based on the signal transmission offset and signal transmission delay parameters of each access module, including: Obtain the unified time reference set by the clock source, and sum the unified time reference and the signal transmission offset of each access module to obtain the initial signal transmission timestamp of each access module. For each access module, the initial signal transmission timestamp is subtracted from the signal transmission delay parameter of the access module to obtain the signal transmission timestamp of the access module.

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