Indoor satellite positioning method and system with multipath error correction

Abstract

The present invention belongs to the technical field of indoor satellite positioning, and specifically provides an indoor satellite positioning method and system with multipath error correction, wherein the method includes GNSS satellite transmitting wireless signals, when the signal is blocked, the indoor wireless device cannot receive the blocked signal, by receiving the unblocked direct path GNSS satellite signal and the GNSS satellite signal bounced by the backscattering node, and returning the original measurement information of the signal; after the wireless device obtains the satellite ephemeris data from the network, it can calculate the actual position of the satellite corresponding to the received satellite signal, obtain the known position of the backscattering node, combine the original measurement information of the received satellite signal, establish a model according to the reflection state of the backscattering node, list the observation equation, and solve the position of the wireless device. The backscattering node of the scheme with low power consumption, small size and low price is attached to the position of the sky visible around the wireless device, and the wireless device can be any device that can receive GNSS signals.

Description

Technical Field

[0001] The present invention relates to the technical field of indoor satellite positioning, and more specifically, to an indoor satellite positioning method and system for multipath error correction. Background Art

[0002] The Global Positioning System (GNSS) has become an indispensable tool for many emerging location-based services, such as navigation, taxi-hailing, augmented reality (AR), etc. Satellite positioning technology has the following characteristics:

[0003] (1) Use the global coordinate system (ECEF) and do not rely on local coordinate positioning;

[0004] (2) The dedicated licensed spectrum is less susceptible to interference than other technologies in ISM frequencies;

[0005] (3) Satellite positioning technology has been deployed and optimized in hundreds of millions of devices, and its applicability has been widely verified.

[0006] However, current satellite positioning technology is limited by the small number of visible satellites indoors, the lack of direct paths, and the large propagation loss in buildings, and cannot be used indoors. In an indoor environment, the GNSS satellite signal that the wireless device can receive is weak, the number of satellite signals that can be received is small, and the location information of the wireless device is unknown. The wireless device only needs to use one or more low-power, small, and cheap backscatter nodes deployed in the surrounding visible sky for positioning. For example, in a shopping mall or station, tourists can use backscatter nodes deployed by the window for indoor positioning. In order to solve the problem of indoor application of satellite positioning technology, indoor satellite positioning is realized. In the existing methods, such as the published papers Jie Liu, Bodhi Priyantha, Ted Hart, Yuzhe Jin, Woosuk Lee, Vijay Raghunathan, Heitor S Ramos, and Qiang Wang. 2015. CO-GPS: Energy efficient GPS sensing with cloud offloading. IEEE Transactions on Mobile Computing 15, 6 (2015), 1348–1361 and Shahriar Nirjon, Jie Liu, Gerald DeJean, Bodhi Priyantha, Yuzhe Jin, and Ted Hart. 2014. COIN-GPS: indoor localization from direct GPS receiving. In Proceedings of the 12th annual international conference on Mobile systems, applications, and services. 301–314, the above-mentioned existing technologies usually achieve indoor GPS satellite signal coverage by adding a high-gain directional antenna at the receiving end or using a relay amplifier. These methods consume large power and are not conducive to integration into handheld wireless devices with limited volume.

[0007] It can be seen that there is currently a lack of a low-power indoor satellite positioning solution suitable for handheld wireless devices. Summary of the invention

[0008] The present invention aims to solve the technical problem of high power consumption of indoor satellite positioning in the prior art.

[0009] The present invention provides an indoor satellite positioning method for multipath error correction, comprising the following steps:

[0010] S1, GNSS satellite transmits wireless signals. When the signal is blocked, the indoor wireless device cannot receive the blocked signal. It receives the unobstructed direct path GNSS satellite signal and the GNSS satellite signal bounced by the backscattering node, and returns the original measurement information of the signal;

[0011] S2, after the wireless device obtains the satellite's ephemeris data from the network, it can calculate the actual position of the satellite corresponding to the received satellite signal, obtain the known position of the backscatter node, combine the original measurement information of the received satellite signal, establish a model according to the reflection state of the backscatter node, list the observation equation, and solve the position of the wireless device.

[0012] Preferably, the S2 specifically includes:

[0013] When the backscatter node bounces the signal, the signal received by the wireless device is the sum of the signal directly emitted by the GNSS satellite and the signal bounced by the backscatter node;

[0014] When the backscatter node does not bounce the signal, the signal received by the wireless device is the signal directly emitted by the GNSS satellite; the wireless device returns the original measurement information based on the received signal.

[0015] Preferably, after receiving the signal, the wireless device needs to first separate the signal bounced by the backscatter node. Specifically, based on the characteristics that the backscatter node can provide considerable gain for weak signals and the GNSS satellite signal receiving module can calculate the GNSS signal strength at the receiving end, the signal bounced by the backscatter node is detected.

[0016] Preferably, the S1 specifically includes: when the number of satellites is insufficient, combining the backscatter nodes and the received satellites for positioning.

[0017] Preferably, the S2 specifically includes: dividing the expansion into direct path expansion and indirect path expansion according to whether the wireless device and the backscatter node are in line of sight;

[0018] State 1: The direct path expands. At time t1, the backscatter node bounces the signal. The wireless device can simultaneously receive the signal from the satellite direct path and the signal from the backscatter node, which is the sum of the two signals.

[0019] In state 2, at time t2, the backscattering node absorbs the signal, and the wireless device can only receive the direct path signal from the satellite.

[0020] Preferably, the S2 specifically includes:

[0021] State 1, the actual propagation distance is:

[0022]

[0023] State 2, the actual propagation distance is:

[0024]

[0025] Where H is the height of the user's handheld wireless device, which is also the vertical height of the backscatter node deployment; The value can be determined with very few iterations, are the lengths of the geometric propagation paths of the signals received by the wireless device at time t1 and t2, i.e., the actual propagation distances of the signals; are the geometric distances from the satellite to the backscatter node at time t1 and t2 respectively. The vector from the backscatter node to the wireless device is called the baseline vector. is the direction vector from the satellite to the backscatter node, is the direction vector from the backscattering node to the center of the earth, is the error correction term, obtained by searching in the range of 0-2H.

[0026] The present invention also provides an indoor satellite positioning system with multipath error correction, wherein the system is used to implement an indoor satellite positioning method with multipath error correction, specifically comprising:

[0027] The original signal measurement module is used to receive the unobstructed direct path GNSS satellite signal and the GNSS satellite signal bounced by the backscattering node when the wireless signal transmitted by the GNSS satellite is blocked. The indoor wireless device cannot receive the blocked signal, and returns the original measurement information of the signal;

[0028] The multipath error correction module is used to calculate the actual position of the satellite corresponding to the received satellite signal after the wireless device obtains the satellite's ephemeris data from the network, obtain the known position of the backscatter node, combine the original measurement information of the received satellite signal, establish a model according to the reflection state of the backscatter node, list the observation equation, and solve the position of the wireless device.

[0029] The present invention also provides an electronic device, comprising a memory and a processor, wherein the processor is used to implement the steps of an indoor satellite positioning method for multipath error correction when executing a computer management program stored in the memory.

[0030] The present invention also provides a computer-readable storage medium on which a computer management program is stored. When the computer management program is executed by a processor, the steps of the indoor satellite positioning method for multipath error correction are implemented.

[0031] Beneficial effects: The present invention provides a method and system for indoor satellite positioning with multipath error correction, wherein the method includes GNSS satellite transmitting wireless signals, when the signal is blocked, the indoor wireless device cannot receive the blocked signal, by receiving the unobstructed direct path GNSS satellite signal and the GNSS satellite signal bounced by the backscattering node, and returning the original measurement information of the signal; after the wireless device obtains the satellite's ephemeris data from the network, it can calculate the actual position of the satellite corresponding to the received satellite signal, obtain the known position of the backscattering node, combine the original measurement information of the received satellite signal, establish a model according to the reflection state of the backscattering node, list the observation equation, and solve the position of the wireless device. The low-power, small-volume, and inexpensive backscattering node of this solution is attached to the position of the sky visible around the wireless device, and the wireless device can be any wireless device that can receive GNSS signals, such as a mobile phone; the backscattering node is used to bounce the wireless signal to change the multipath propagation characteristics of the wireless signal, and ultimately help the wireless device to locate indoors. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A flowchart of an indoor satellite positioning method for multipath error correction provided by the present invention;

[0033] Figure 2 A schematic diagram of the hardware structure of a possible electronic device provided by the present invention;

[0034] Figure 3 A schematic diagram of the hardware structure of a possible computer-readable storage medium provided by the present invention;

[0035] Figure 4 A schematic diagram of the modeling and correction principle of the indoor multipath situation provided by the present invention;

[0036] Figure 5 A schematic diagram of the present invention when a signal is blocked;

[0037] Figure 6 Schematic diagram of backscatter node rebound provided by the present invention

[0038] Figure 7 Two state principle diagrams of multipath error provided by the present invention;

[0039] Figure 8 Schematic diagram of two states at time t1 and t2 provided by the present invention;

[0040] Fig. 9 A schematic diagram of the indoor satellite positioning method for multipath error correction provided by the present invention; DETAILED DESCRIPTION

[0041] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0042] like Figure 1 As shown, an indoor satellite positioning method with multipath error correction provided by an embodiment of the present invention includes a GNSS satellite transmitting a wireless signal. When the signal is blocked, the indoor wireless device cannot receive the blocked signal. By receiving the unobstructed direct path GNSS satellite signal and the GNSS satellite signal bounced by the backscattering node, and returning the original measurement information of the signal; after the wireless device obtains the satellite's ephemeris data from the network, it can calculate the actual position of the satellite corresponding to the received satellite signal, obtain the known position of the backscattering node, and combine the original measurement information of the received satellite signal. According to the reflection state of the backscattering node, a model is established, the observation equation is listed, and the position of the wireless device is solved. The backscattering node of this solution is low in power consumption, small in size, and cheap, and is attached to the position of the sky visible around the wireless device. The wireless device can be any wireless device that can receive GNSS signals, such as a mobile phone; the backscattering node is used to bounce the wireless signal to change the multipath propagation characteristics of the wireless signal, and finally help the wireless device to locate indoors.

[0043] This solution does not require any hardware / firmware modification to the wireless device and is easy to deploy and promote. Backscatter nodes are deployed in the wireless devices that need to be positioned indoors; the wireless devices receive the satellite navigation system (GNSS, Global Navigation Satellite System) satellite signals and direct GNSS satellite signals reflected by the backscatter nodes; the carrier-to-noise ratio of the GNSS signal is separated to obtain the backscatter node bounce signal and the direct GNSS satellite signal; the cumulative carrier phase of the GNSS satellite signals of the direct path and the reflected path is measured, and the GNSS satellite ephemeris and the backscatter node reference position information are integrated to locate the position of the indoor wireless device. When there are few visible GNSS satellites indoors and the GNSS satellite signals are weak, the present invention controls the backscatter signal transmission circuit to switch between the bounced GNSS signal and the absorbed GNSS signal, thereby achieving accurate positioning of the wireless device indoors.

[0044] The low-power, small-sized, and inexpensive backscatter nodes of this solution are attached to locations where the sky is visible around wireless devices. The wireless devices can be any device that can receive GNSS signals, such as mobile phones. The backscatter nodes are used to bounce wireless signals to change the multipath propagation characteristics of wireless signals, ultimately helping wireless devices to locate indoors.

[0045] In a specific implementation scenario, in an indoor environment, that is, the GNSS satellite signal that the wireless device can receive is weak, the number of satellite signals that can be received is small, and the location information of the wireless device is unknown, the wireless device only needs to use one or more low-power, small, and cheap backscatter nodes deployed in the surrounding visible sky for positioning. For example, in a shopping mall or a station, tourists can use the backscatter nodes deployed by the window for indoor positioning.

[0046] Based on this scenario, one or more low-power, small, and inexpensive backscatter nodes are attached to locations where the sky is visible around wireless devices. The wireless devices can be any devices that can receive GNSS signals, such as mobile phones. The backscatter nodes are used to bounce wireless signals to change the multipath propagation characteristics of wireless signals, ultimately helping wireless devices to locate indoors.

[0047] The present invention designs the backscattering node to be attached to a visible sky position around the wireless device, and the backscattering node is used to bounce wireless signals to change the multipath propagation of wireless signals. The embodiments of the present invention have the following technologies, including:

[0048] (1) Backscatter-assisted positioning technology: After distinguishing the satellite signals after being ejected from the satellite signals in the direct path, the real-time position of the satellite is calculated based on the satellite's ephemeris data. Combined with the known position coordinates of the backscatter node, the cumulative observation values ​​of the satellite signals are sampled in a short period of time to build a model.

[0049] The traditional positioning model requires signal data from at least four satellites. In the positioning model established by this patent, when the number of satellites is insufficient, the backscatter nodes can be used in combination with the received satellites for positioning, so that the minimum number of satellites involved in positioning is less than the minimum number of satellites for traditional positioning. For example, in a certain indoor environment, the mobile phone can only receive signals from satellite A and satellite B. At this time, the number of satellites is 2, which is less than the 4 satellites required by the traditional positioning model. When the backscatter nodes a and b are deployed at appropriate locations, there are two satellites and two backscatter nodes. The mobile phone can receive signals directly from satellites A and B and reflected signals from backscatter nodes a and b. Combined modeling can obtain the location of the mobile phone and complete the positioning. Figure 6 shown.

[0050] (2) Multipath error correction technology: Due to the complex indoor environment and the relative movement of the satellite to the ground, the receiving wireless device may not be able to receive the direct signal from the satellite, but instead receives the reflected signal from other indoor reflective surfaces. At the same time, there may be obstructions between the backscatter node and the receiving wireless device, so that the signal amplified and reflected by the backscatter node cannot be directly transmitted to the receiving wireless device, resulting in positioning errors. The above two situations are divided into the path expansion caused by multipath reflection when the backscatter node is within the line of sight of the receiving wireless device and when it is not in the line of sight.

[0051] The specific scheme principle process is as follows:

[0052] (1) Figure 5 As shown, the GNSS satellite transmits a wireless signal. When the signal is blocked, the indoor wireless device cannot receive the blocked signal, but can receive the unobstructed direct path GNSS satellite signal and the GNSS satellite signal bounced by the backscattering node, and return the original measurement information of the signal; after the wireless device eliminates the noise of the signal carrier-to-noise ratio, it separates the original measurement information of the signal corresponding to the backscattering node bounce path and the original measurement information of the signal that has not been bounced by the backscattering node according to the strength characteristics of the signal carrier-to-noise ratio;

[0053] (2) Figure 6 As shown, after the wireless device obtains the satellite's ephemeris data from the network, it can calculate the actual position of the satellite corresponding to the received satellite signal, obtain the known position of the backscatter node, combine the original measurement information of the received satellite signal, establish a model based on the two states of the backscatter node, list the observation equation, and solve the position of the wireless device;

[0054] (3) Figure 7 As shown, the indoor conditions where wireless devices are located are complex. In order to improve the accuracy of indoor positioning and enhance robustness, two common models of indoor multipath error are proposed, and the model is corrected to reduce the error.

[0055] Specifically, the GNSS satellite transmits a wireless positioning signal, and the wireless device receives the signal indoors. When the backscatter node bounces the signal, the signal received by the wireless device is the sum of the direct signal from the GNSS satellite and the signal bounced by the backscatter node; when the backscatter node does not bounce the signal, the signal received by the wireless device is the direct signal from the GNSS satellite; the wireless device returns the original measurement information based on the received signal.

[0056] like Figure 8 As shown, the wireless device first needs to separate the signal bounced by the backscatter node. This solution uses the characteristics that the backscatter node can provide considerable gain for weak signals and the GNSS satellite signal receiving module can calculate the GNSS signal strength at the receiving end to detect the signal bounced by the backscatter node.

[0057] The backscatter node has the characteristics of high sensitivity and high gain, and can reflect and amplify weak GNSS satellite signals on the ground. When the backscatter node bounces the signal, the wireless device will receive the sum of the GNSS satellite signal and the bounced signal of the backscatter node. Compared with when the backscatter node does not bounce the signal, the wireless device can only receive the direct GNSS satellite signal, and the amplified sum signal strength is stronger than the direct path signal. In the original measurement information of the GNSS satellite signal, the carrier-to-noise ratio, that is, the carrier-to-noise ratio, can intuitively reflect the strength of the signal.

[0058] like Figure 8 As shown in the figure, according to the reflection state of the backscattering node, the system state is divided into two states. At time t2, the backscattering node absorbs the signal, and the wireless device can only receive the direct path signal from the satellite; at time t1, the backscattering node bounces the signal, and the wireless device can simultaneously receive the signal from the direct path of the satellite and the signal from the backscattering node, which is the sum of the two signals.

[0059] At any time, the signal from the GNSS satellite passes through the atmosphere to reach the ground. The ionosphere and troposphere in the atmosphere will cause electromagnetic waves to scatter, reflect, and diffract, resulting in a certain time delay in the signal. In the positioning system of the GNSS receiver, the position is determined by the measurement of the signal propagation path, so the positioning accuracy depends on the accurate measurement of the signal propagation time. The error caused by the atmosphere varies with time and is difficult to accurately measure and estimate. Therefore, the distance measurement error caused by the ionosphere and troposphere delay is recorded as I and T respectively.

[0060] remember are the lengths of the geometric propagation paths of the signals received by the wireless device at time t1 and t2, that is, the actual propagation distance of the signal. To improve positioning accuracy, the phase of the GNSS satellite carrier is measured on the wireless device, denoted as Φ, which has distance units and represents the accumulated wave path after the wireless device captures and locks the satellite carrier signal. Since the carrier signal is periodic, an integer ambiguity distance error N will be generated when locked. The receiving wireless device measures the signal propagation delay. Since the clock stability of the local system is very different from the performance of the satellite's onboard atomic clock, it is called clock error, and the distance error generated is recorded as (t (R,t) -t (S,t) ). For two adjacent different state moments, we have:

[0061] t1:

[0062] t2:

[0063] The interval between t1 and t2 is very short, during which the state of the atmosphere can be considered unchanged, and the resulting atmospheric delay remains consistent; is the distance error caused by the propagation delay of the signal in the backscattering node, which can be measured by the instrument, ε Φ represents the error term of phase measurement; since the satellite is far away from the ground, the distance from the backscattering node to the wireless device is much smaller than the distance to the satellite, so it can be considered that the satellite signal reaches the ground in parallel; are the geometric distances from the satellite to the backscatter node at time t1 and t2 respectively. The vector from the backscatter node to the wireless device is called the baseline vector. The unit direction vector from the satellite to the wireless device at time t1 is are all three-dimensional space vectors, then:

[0064]

[0065]

[0066]

[0067] Φ d =Φ1-Φ2,

[0068] N d =N1-N2,

[0069]

[0070] have to:

[0071]

[0072] Solving for the baseline vector That is, the position of the wireless device relative to the backscattering node, and the equation is transformed to

[0073]

[0074] The left side of the equal sign contains the observed values ​​and known calculated values, and the right side of the equal sign contains the quantity to be solved. At this time, the equation is a nonlinear equation and is difficult to solve, so the nonlinear equation is linearized and solved.

[0075] like Fig. 9 As shown, according to Newton's method, the equation Linear expansion,

[0076]

[0077] remember

[0078]

[0079] but:

[0080]

[0081] It contains four unknown quantities, namely the three-dimensional position information of the baseline vector and the clock error of the wireless device. Four linearly independent equations are needed to solve them. If the number of available satellites is m and the number of backscatter nodes is n, the solution can be completed if m·n≥4.

[0082] Then use the iterative weighted least squares (WLS) algorithm:

[0083]

[0084] Substituting the backscatter node bounce signal and direct signal into the calculation, we get:

[0085]

[0086] Where W represents the weight matrix, which is determined by the quality of the received satellite signal, and G is obtained by expanding the unit direction vector between the satellite and the receiving device. After several iterations of WLS operations, until the position converges to a certain range, the final position is obtained by substituting into the following formula:

[0087]

[0088] in represents the actual baseline vector of the receiving device, represents the initial baseline vector of the iteration, is the baseline vector convergence vector obtained through iteration. The obtained baseline vector is the relative position relative to the reference backscattering node, and the absolute position of the wireless device can be obtained by conversion.

[0089] like Figure 4 As shown in the figure, due to the complex and changeable indoor environment, wireless signals are prone to complex multipath propagation indoors, which causes the actual signal propagation path received by the wireless device to not completely conform to the propagation path in the above model. Substituting it into the calculated positioning result will produce certain errors. Therefore, it is necessary to model and correct the indoor multipath situation to reduce the error. When the wireless device receives the navigation signal transmitted by the satellite, it can jointly determine whether the received signal is an indirect signal through the parameters "multipath flag" and "carrier phase lock state". On this basis, two multipath models are proposed and analyzed. According to whether the wireless device and the backscatter node are in line of sight, they are divided into direct path expansion and indirect path expansion.

[0090] In direct path expansion, the satellite direct path is blocked, and the satellite signal is received by the wireless device after being reflected by other reflective surfaces. At this time, the path is expanded relative to the original path, and a half-wave loss is generated at the reflection point:

[0091]

[0092] H is the height of the user's handheld wireless device, which is also the vertical height of the backscatter node deployment, and H≈1.2m.

[0093] In the case of non-direct path expansion, the reflection path of the backscattering node is blocked, and the reflected signal is received by the wireless device after being reflected by other reflection surfaces. At this time, the path is expanded relative to the original path, and a half-wave loss is generated at the reflection point:

[0094]

[0095] The value can be determined with very few iterations.

[0096] Where H is the height of the user's handheld wireless device, which is also the vertical height of the backscatter node deployment, and H≈1.2m; The value can be determined with very few iterations, are the lengths of the geometric propagation paths of the signals received by the wireless device at time t1 and t2, i.e., the actual propagation distances of the signals; are the geometric distances from the satellite to the backscatter node at time t1 and t2 respectively. The vector from the backscatter node to the wireless device is called the baseline vector. The unit direction vector from the satellite to the wireless device at time t1 is are all three-dimensional space vectors, is the direction vector from the satellite to the backscatter node, is the direction vector from the backscattering node to the center of the earth, is the error correction term, obtained by searching in the range of 0-2H.

[0097] By using the above two error analysis models and performing flexible calculations in actual scenarios, errors can be reduced and accurate indoor positioning can be ultimately achieved.

[0098] Through the present invention, there is no need to modify the hardware or driver of the wireless device, and accurate positioning can be achieved even in an environment where the number of visible satellites indoors is difficult to satisfy the traditional positioning algorithm.

[0099] The present invention also provides an indoor satellite positioning system with multipath error correction, the system is used to implement the indoor satellite positioning method with multipath error correction as described above, specifically comprising:

[0100] The original signal measurement module is used to receive the unobstructed direct path GNSS satellite signal and the GNSS satellite signal bounced by the backscattering node when the wireless signal transmitted by the GNSS satellite is blocked. The indoor wireless device cannot receive the blocked signal, and returns the original measurement information of the signal;

[0101] The multipath error correction module is used to calculate the actual position of the satellite corresponding to the received satellite signal after the wireless device obtains the satellite's ephemeris data from the network, obtain the known position of the backscatter node, combine the original measurement information of the received satellite signal, establish a model according to the reflection state of the backscatter node, list the observation equation, and solve the position of the wireless device.

[0102] See also Figure 2 Schematic diagram of an electronic device provided by an embodiment of the present invention. Figure 2 As shown, an embodiment of the present invention provides an electronic device, including a memory 1310, a processor 1320, and a computer program 1311 stored in the memory 1310 and executable on the processor 1320. When the processor 1320 executes the computer program 1311, the following steps are implemented: S1, a GNSS satellite transmits a wireless signal. When the signal is blocked, the indoor wireless device cannot receive the blocked signal. The GNSS satellite signal of the unobstructed direct path and the GNSS satellite signal bounced by the backscattering node are received, and the original measurement information of the signal is returned;

[0103] S2, after the wireless device obtains the satellite's ephemeris data from the network, it can calculate the actual position of the satellite corresponding to the received satellite signal, obtain the known position of the backscatter node, combine the original measurement information of the received satellite signal, establish a model according to the reflection state of the backscatter node, list the observation equation, and solve the position of the wireless device.

[0104] See also Figure 3 Schematic diagram of an embodiment of a computer-readable storage medium provided by the present invention. Figure 3 As shown, this embodiment provides a computer-readable storage medium 1400, on which a computer program 1411 is stored. When the computer program 1411 is executed by a processor, the following steps are implemented: S1, a GNSS satellite transmits a wireless signal. When the signal is blocked, the indoor wireless device cannot receive the blocked signal. The unblocked direct path GNSS satellite signal and the GNSS satellite signal bounced by the backscattering node are received, and the original measurement information of the signal is returned;

[0105] S2, after the wireless device obtains the satellite's ephemeris data from the network, it can calculate the actual position of the satellite corresponding to the received satellite signal, obtain the known position of the backscatter node, combine the original measurement information of the received satellite signal, establish a model according to the reflection state of the backscatter node, list the observation equation, and solve the position of the wireless device.

[0106] It should be noted that in the above embodiments, the description of each embodiment has its own emphasis, and for parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0107] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0108] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded computer, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0109] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0110] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1The steps for the functions specified in one or more boxes.

[0111] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0112] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A multipath error corrected indoor satellite positioning method, characterized in that: The following steps are involved: S1, GNSS satellite transmits wireless signals. When the signal is blocked, the indoor wireless device cannot receive the blocked signal. It receives the unobstructed direct path GNSS satellite signal and the GNSS satellite signal bounced by the backscattering node, and returns the original measurement information of the signal; S2, after the wireless device obtains the satellite's ephemeris data from the network, it can calculate the actual position of the satellite corresponding to the received satellite signal, obtain the known position of the backscattering node, combine the original measurement information of the received satellite signal, establish a model based on the reflection state of the backscattering node, list the observation equation, and solve the position of the wireless device; S2 specifically includes: dividing into direct path expansion and indirect path expansion according to whether the wireless device and the backscatter node are in line of sight; State 1: The direct path expands. At time t1, the backscatter node bounces the signal. The wireless device can simultaneously receive the signal from the satellite direct path and the signal from the backscatter node, which is the sum of the two signals. State 2: At time t2, the backscattering node absorbs the signal, and the wireless device can only receive the direct path signal from the satellite; The S2 specifically includes: State 1, the actual propagation distance is: State 2, the actual propagation distance is: Where H is the height of the user's handheld wireless device, which is also the vertical height of the backscatter node deployment; The value can be determined with very few iterations, are the lengths of the geometric propagation paths of the signals received by the wireless device at time t1 and t2, i.e., the actual propagation distances of the signals; are the geometric distances from the satellite to the backscatter node at time t1 and t2 respectively. The vector from the backscatter node to the wireless device is called the baseline vector. is the direction vector from the satellite to the backscatter node, is the direction vector from the backscattering node to the center of the earth, is the error correction term, obtained by searching in the range of 0-2H.

2. The indoor satellite positioning method with multipath error correction according to claim 1, characterized in that: The S2 specifically includes: When the backscatter node bounces the signal, the signal received by the wireless device is the sum of the signal directly emitted by the GNSS satellite and the signal bounced by the backscatter node; When the backscatter node does not bounce the signal, the signal received by the wireless device is the signal directly emitted by the GNSS satellite; the wireless device returns the original measurement information based on the received signal.

3. The indoor satellite positioning method with multipath error correction according to claim 2, characterized in that: After receiving the signal, the wireless device needs to first separate the signal bounced by the backscatter node. Specifically, based on the characteristics that the backscatter node can provide considerable gain for weak signals and the GNSS satellite signal receiving module can calculate the GNSS signal strength at the receiving end, the signal bounced by the backscatter node is detected.

4. The indoor satellite positioning method with multipath error correction according to claim 1, characterized in that: The S1 specifically includes: when the number of satellites is insufficient, combining the backscatter nodes with the received satellites for positioning.

5. An indoor satellite positioning system with multipath error correction, characterized in that: The system is used to implement the indoor satellite positioning method for multipath error correction as described in any one of claims 1 to 4, specifically comprising: The original signal measurement module is used to receive the unobstructed direct path GNSS satellite signal and the GNSS satellite signal bounced by the backscattering node when the wireless signal transmitted by the GNSS satellite is blocked. The indoor wireless device cannot receive the blocked signal, and returns the original measurement information of the signal; The multipath error correction module is used to calculate the actual position of the satellite corresponding to the received satellite signal after the wireless device obtains the satellite's ephemeris data from the network, obtain the known position of the backscatter node, combine the original measurement information of the received satellite signal, establish a model according to the reflection state of the backscatter node, list the observation equation, and solve the position of the wireless device.

6. An electronic device, characterized in that: It comprises a memory and a processor, wherein the processor is used to implement the steps of the indoor satellite positioning method for multipath error correction as described in any one of claims 1 to 4 when executing a computer management program stored in the memory.

7. A computer-readable storage medium, characterized in that: A computer management program is stored thereon, and when the computer management program is executed by a processor, the steps of the indoor satellite positioning method for multipath error correction as described in any one of claims 1 to 4 are implemented.

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