A pseudo-satellite-based indoor positioning system and method

Abstract

This invention discloses an indoor positioning system and method based on pseudosatellites, comprising: an outdoor receiver, an indoor transmitter, and a main control unit; the indoor transmitter is a multi-antenna transmitter, and its transmission signal coverage area is divided into multiple transmission zones; the outdoor receiver receives GNSS signals from visible satellites and sends the GNSS signals to the main control unit; the main control unit calculates the location information of the outdoor receiver based on the received GNSS signals, and modifies the pseudorange of the calculated location information by modifying the C / A code phase based on the location information of the transmission zones and the location information of the outdoor receiver, thereby obtaining a pseudo GNSS signal corresponding to the transmission zone and sending it to the indoor transmitter, and controlling the beam direction of the indoor transmitter; the indoor transmitter transmits the pseudo GNSS signal to the corresponding transmission zone under the control of the main control unit. This invention enables signal transmission to multiple different transmission zones using a single indoor transmitter, resulting in lower equipment and maintenance costs.

Description

Technical Field

[0001] This invention belongs to the field of positioning technology, specifically relating to an indoor positioning system and method based on pseudo-satellites. Background Technology

[0002] Indoor positioning has always been a research hotspot. Due to interference from walls and other factors, users cannot receive clear GNSS signals indoors. Currently, Bluetooth and Wi-Fi are generally used for assisted positioning, mainly through the range intersection method. Based on RSSI signal strength measurement, a signal strength attenuation model is used to convert the signal attenuation from the access point to the receiver into the distance between them. Triangulation is then used to estimate the receiver's position based on distance constraints between three or more access points and the receiver. However, because the signal strength attenuation model is strongly correlated with the indoor environment, and the indoor environment is complex, variable, and has significant non-line-of-sight phenomena, it is difficult to obtain an accurate signal strength attenuation model. This method requires at least three transmitters indoors, and the solution system needs additional design.

[0003] Most proposed indoor positioning methods are based on fingerprint-like algorithms, requiring the prior measurement of a standard reference map. After a user enters the positioning area, feature information is collected in real-time, and the collected data is compared with the stored reference map. Based on relevant criteria, the best matching result is obtained, enabling autonomous positioning of the vehicle. However, this method first requires building a fingerprint database. Site gridding, grid point signal fingerprint collection, and fingerprint database correction all consume considerable human and material resources, significantly limiting the practical application of indoor positioning technology.

[0004] Literature CN110456307B discloses a terminal positioning method based on the carrier-to-noise ratio of indoor pseudo-satellite signals. This method establishes an indoor signal strength database and compares the received pseudo-satellite signal strength with the database to achieve positioning. However, this method first requires building a fingerprint database; site gridding, grid point signal fingerprint collection, and fingerprint database correction all consume considerable manpower and resources. Literature CN105425259B proposes an indoor positioning method based on inverse GNSS nodes. One indoor transmitter corresponds to a fixed area. When the indoor area is large or the positioning accuracy requirement is high, more areas need to be divided, requiring more indoor transmitters, leading to high costs. Furthermore, this method requires all indoor transmitters to continuously transmit signals into the area and refresh in real time, resulting in resource waste.

[0005] Reference CN104035068B deploys three or more pseudo-satellite base stations equipped with barometric altimeters indoors. The three-dimensional positions of the pseudo-satellites are encoded according to a specific format to generate navigation messages, which are then modulated and transmitted via antenna. This method requires the user end to also be equipped with temperature and barometric sensors. After receiving the signals transmitted by the pseudo-satellite base stations, the receiver combines the barometric altimeter information to achieve three-dimensional positioning. Reference CN113848573A proposes a seamless indoor-outdoor positioning method. The master control end allocates the captured satellites in the sky to the indoor pseudo-satellites based on the carrier-to-noise ratio, but an additional reference transmitter is needed to calculate the distance and angle between the transmitter and the indoor target to achieve indoor-outdoor positioning. Reference CN109839615 proposes an indoor positioning system using the UKF algorithm. This system aims to solve the problem of the impact of nonlinear errors on indoor positioning by constructing a pseudo-satellite double-difference pseudorange observation model to eliminate the influence of receiver clock errors, etc. However, its universality is not high, and it requires the design of additional receiver algorithms. Document CN113820730A designs an indoor positioning system based on BeiDou, requiring the setting of additional BeiDou active beacons and the construction of a BeiDou pseudo-satellite fixed scattering point model. Users need to achieve 3D positioning through active beacons, scattering point models, and pseudo-satellites, which is complex and cannot meet the needs of most application scenarios. Document CN113093251B sets reference points in the positioning environment in advance and achieves positioning by comparing the similarity between the user target and the reference points. Document CN106767831A uses an outdoor receiver to collect its own positioning information, and an indoor transmitter generates an analog signal with similar satellite bands and frequencies. It simply transmits external GNSS signals through the system, without pseudorange modification, but there are synchronization issues. Document CN105549052A designs an indoor positioning method based on GNSS repeaters, combining pseudo-satellite and GNSS repeater technologies. It requires all repeaters to be connected to an outdoor antenna by cable, and measures the distance from different repeaters to the receiver by different satellite signals. There is no signal modification, but the cable length may cause repeater misjudgments.

[0006] In conclusion, although there are various indoor positioning methods available, each has its own drawbacks. Summary of the Invention

[0007] To address the problems of indoor positioning in the existing technologies, this invention provides an indoor positioning system and method based on pseudo-satellites, which solves the problem of indoor blind spots for satellite signals. It uses satellite signals for positioning, which has high accuracy and can achieve seamless integration between indoor and outdoor environments. Furthermore, it can transmit signals to multiple different transmission areas through a single indoor transmitter, resulting in lower equipment and maintenance costs.

[0008] This invention is achieved through the following technical solution:

[0009] An indoor positioning system based on pseudosatellites includes: an outdoor receiver, an indoor transmitter, and a main control terminal; the indoor transmitter is a multi-antenna transmitter; the indoor transmitter's signal coverage area is divided into multiple transmission zones.

[0010] An outdoor receiver is used to receive GNSS signals from visible satellites and send the GNSS signals to the main control unit.

[0011] The main control unit is used to receive GNSS signals transmitted by the outdoor receiver, calculate the location information of the outdoor receiver based on the received GNSS signals, and modify the pseudorange of the calculated location information by modifying the C / A code phase based on the location information of the transmission area and the location information of the outdoor receiver, so as to obtain a pseudo GNSS signal corresponding to the transmission area and send it to the indoor transmitter; it is also used to control the beam direction of the indoor transmitter.

[0012] The indoor transmitter is used to receive pseudo-GNSS signals sent by the master control unit and, under the control of the master control unit, transmit pseudo-GNSS signals to the corresponding transmission area.

[0013] Preferably, the outdoor receiver is a GNSS receiver.

[0014] Preferably, the main control terminal includes a GNSS calculation module, a pseudorange modification module, and a transmission control module;

[0015] The GNSS resolution module is used to calculate the location information of the outdoor receiver based on the received GNSS signals.

[0016] The pseudorange modification module modifies the calculated position information by modifying the C / A code phase based on the location information of the transmitting area and the location information of the outdoor receiver, and reconstructs it into a pseudo GNSS signal corresponding to the transmitting area.

[0017] The transmission control module is used to control the beam direction of the indoor transmitter, enabling the indoor transmitter to transmit pseudo-GNSS signals to the corresponding transmission area.

[0018] Preferably, the indoor transmitter only transmits pseudo-GNSS signals to the transmission area where there are user receivers.

[0019] Preferably, several indoor transmitters are provided, and the transmission signal coverage range of each indoor transmitter is different.

[0020] A pseudo-satellite-based indoor positioning method, based on the aforementioned system, includes:

[0021] Step 1: The outdoor receiver receives GNSS signals from visible satellites and sends the GNSS signals to the main control unit;

[0022] Step 2: The main control unit receives the GNSS signal sent by the outdoor receiver and calculates the location information of the outdoor receiver.

[0023] Step 3: Based on the location information of the transmission area and the location information of the outdoor receiver, the main control terminal modifies the pseudorange of the calculated outdoor receiver location information by modifying the C / A code phase, obtains the pseudo GNSS signal corresponding to the transmission area, and sends it to the indoor transmitter.

[0024] Step 4: The indoor transmitter receives the pseudo GNSS signal, and the main control unit controls the beam direction of the indoor transmitter so that the indoor transmitter transmits the pseudo GNSS signal to the corresponding transmission area.

[0025] Step 5: The user receiver receives the pseudo GNSS signal and calculates the user receiver's position information based on the pseudo GNSS signal.

[0026] Preferably, in step 1, the outdoor receiver amplifies the received GNSS signal and sends it to the main control terminal as an analog signal.

[0027] Preferably, in step 5, the user receiver is a receiver capable of processing GNSS signals.

[0028] Preferably, in step 4, the indoor transmitter transmits pseudo-GNSS signals only to the transmission area where there are user receivers.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] This invention's system primarily consists of an outdoor receiver receiving GNSS signals, a main control unit extracting satellite navigation information from the GNSS signals, and after signal processing to modify the pseudorange, an indoor transmitter transmitting the modified GNSS signals as pseudo-satellites. User receivers do not require modification; existing GNSS positioning software can be used to calculate the user's location, making it suitable for use in large venues such as shopping malls. Furthermore, since the user receiver consistently receives GNSS signals, it can immediately perform positioning upon receiving the pseudo-satellite signal after moving indoors, achieving seamless integration of outdoor and indoor positioning. The indoor transmitter is a multi-antenna transmitter, with the main control unit controlling its beam direction. This allows a single indoor transmitter to transmit pseudo-GNSS signals to different transmission areas. Therefore, this invention enables signal transmission to multiple different transmission areas with a single indoor transmitter, resulting in lower equipment and maintenance costs and easier management and control compared to setting up a separate indoor transmitter for each transmission area. By deploying virtual satellites, this invention achieves comprehensive GNSS satellite signal coverage in indoor environments, solving the problem of indoor satellite signal blind spots. The system of this invention has high versatility and does not require modification of the user receiver. Any terminal that can parse satellite signals can extract the positioning information.

[0031] Furthermore, this invention controls the beam direction of the indoor transmitter through the main control terminal, transmitting pseudo-GNSS signals only to the area where the user receiver is located. The indoor transmitter selectively transmits signals, stopping transmission to a certain area when there are no users in that area, thus saving resources.

[0032] This invention designs a method for indoor positioning by modifying the pseudorange of GNSS signals using an outdoor receiver and an indoor pseudosatellite. GNSS positioning primarily relies on pseudorange measurement. The satellite emits a ranging code according to its own clock, which travels over time to the GNSS receiver. The receiver, under its own clock, generates a set of identically structured replica codes. The delay time is determined by comparing the phases of the two replica codes. Pseudorange modification can be achieved by modifying the C / A code phase, resulting in a pseudo-GNSS signal. The beam direction of the indoor transmitter is controlled by the master control unit, enabling the indoor transmitter to send the pseudo-GNSS signal to indoor users. This allows a single indoor transmitter to transmit signals to different transmission areas. This invention solves the indoor blind zone problem of satellite signals, using satellite signal positioning with high accuracy and low cost, and achieving seamless integration between indoor and outdoor positioning. Attached Figure Description

[0033] Figure 1 This refers to the position information of the original GNSS signal in the simulation of this invention;

[0034] Figure 2This refers to the positioning information after the first pseudorange modification in the simulation of this invention;

[0035] Figure 3 This refers to the positioning information after the second pseudorange modification in the simulation of this invention;

[0036] Figure 4 This is a schematic diagram of the components of the pseudo-satellite-based indoor positioning system of the present invention;

[0037] In the diagram: 1 is a visible satellite, 2 is an outdoor receiver, 3 is the main control unit, 4 is an indoor transmitter, and 5 is a user receiver. Detailed Implementation

[0038] To further understand the present invention, the present invention will be described below with reference to embodiments. These descriptions are only for further explaining the features and advantages of the present invention and are not intended to limit the claims of the present invention.

[0039] This invention relates to an indoor positioning system based on pseudo-satellites, comprising: an outdoor receiver 2, an indoor transmitter 4, and a main control terminal 3; the indoor transmitter is a multi-antenna transmitter; the indoor transmitter's signal coverage area is divided into multiple transmission zones.

[0040] Outdoor receiver 2 is used to receive GNSS signals from visible satellite 1, amplify the GNSS signals, and send them to the main control terminal 3 as analog signals;

[0041] The main control unit 3 is used to receive the GNSS signal transmitted by the outdoor receiver 2, calculate the position information of the outdoor receiver 2 based on the received GNSS signal, and modify the pseudorange of the calculated position information of the outdoor receiver 2 by modifying the C / A code phase according to the position of the transmission area and the position information of the outdoor receiver 2, so as to obtain a pseudo GNSS signal corresponding to the transmission area and send it to the indoor transmitter 4; it is used to control the beam direction of the indoor transmitter using beamforming technology; the position information of the transmission area is obtained by surveying and mapping.

[0042] Indoor transmitter 4 is used to receive pseudo GNSS signals sent by the main control terminal 3, and under the control of the main control terminal, transmits the received pseudo GNSS signals to the corresponding transmission area.

[0043] The main control terminal 3 of the present invention includes a GNSS calculation module, a pseudorange modification module and a transmission control module;

[0044] The GNSS calculation module at the main control end is used to calculate the location information of the outdoor receiver based on the received GNSS signals;

[0045] The pseudorange modification module of the main control unit is used to modify the pseudorange of the calculated outdoor receiver 2 position information by modifying the C / A code phase based on the position of the transmitting area and the position information of the outdoor receiver 2, and reconstruct it into a pseudo GNSS signal corresponding to the transmitting area.

[0046] The main control module's transmission control module uses beamforming technology to control the beam direction of the indoor transmitter, enabling the transmission of pseudo-GNSS signals to corresponding transmission areas. This invention can transmit pseudo-GNSS signals simultaneously to all transmission areas, but more preferably, it transmits pseudo-GNSS signals only to transmission areas with user receivers. When a user moves from one area to another, such as... Figure 4 As shown, the transmission control module controls the beam direction of the indoor transmitter to transmit to the transmission area where the user receiver is located.

[0047] The outdoor receiver 2 described in this invention is a GNSS receiver and is placed in an open environment, such as the top of a building, where clear satellite signals can be received.

[0048] The indoor transmitter 4 described in this invention can be configured with one or more units, for example, three or more, depending on the size of the indoor area. Each indoor transmitter has a different signal coverage range. The signal coverage range of each indoor transmitter is divided into transmission areas, and the transmission control module controls the indoor transmitters to transmit pseudo-GNSS signals to different transmission areas. The total coverage range of all indoor transmitters is required to cover the entire indoor area. The indoor transmitters transmit pseudo-GNSS analog signals, and the reconstructed pseudo-GNSS signals should include all visible satellite signals in the air. All indoor transmitters in this invention are connected to a main control unit, where the transmission control module uniformly manages and controls the indoor transmitters, coordinating their pseudo-GNSS signal transmission. This approach reduces the number of antennas required, allows the transmission control module to adjust the signal transmission direction of the indoor transmitters to the user's transmission area, and flexibly adjusts the power of each indoor transmitter, improving resource utilization.

[0049] As a preferred method, when user receiver 5 moves from one area to another, the main control unit controls the beam direction of the indoor transmitter to transmit pseudo-GNSS signals towards the area where the user receiver is located, and does not transmit signals to areas without user receivers. User receiver 5 receives the pseudo-GNSS signals and calculates its location information based on them.

[0050] User receiver 5 is a receiver capable of processing GNSS signals; it is an existing GNSS receiver and requires no modifications.

[0051] The indoor positioning method of this invention is achieved by transmitting pseudo-GNSS signals through an indoor transmitter. The specific process includes:

[0052] Step 1: The outdoor receiver receives GNSS signals from visible satellites, amplifies and forwards the GNSS signals to collect its own positioning information, and sends it to the main control terminal in the form of analog signals;

[0053] Step 2: The main control unit receives the GNSS signal sent by the outdoor receiver, and calculates the navigation information in the GNSS signal to obtain the location information of the outdoor receiver;

[0054] Step 3: Based on the location information of the transmission area and the location information of the outdoor receiver 2, the main control terminal modifies the pseudorange of the calculated location information of the outdoor receiver 2 by modifying the C / A code phase. The modified pseudo GNSS signal is then sent to the indoor transmitter. The main control terminal controls the beam direction of the indoor transmitter so that the indoor transmitter transmits the pseudo GNSS signal to the corresponding transmission area. Since the indoor area division method is known in advance, the pseudorange modification can be calculated in advance and does not need to be calculated in real time.

[0055] Step 4: The user receiver receives the pseudo GNSS signal. Based on the GNSS positioning principle, the user receiver mainly uses pseudorange for positioning and calculates the user receiver's position information based on the pseudo GNSS signal.

[0056] In this invention, indoor transmission zones are pre-defined and stored in the main control unit. The main control unit controls indoor transmitters to transmit pseudo-GNSS signals into the indoor area. The indoor transmitters are multi-antenna transmitters composed of antenna arrays. When transmitting pseudo-GNSS signals, under the control of the main control unit, the indoor transmitters preferentially transmit towards the transmission zone where the user receiver is located. As the user moves within the indoor area, the indoor transmitters selectively transmit, sending signals to transmission zones with user receivers. When there are no users in a transmission zone, transmission to that zone stops, thus saving resources.

[0057] The area division in this invention is not a fingerprint-based positioning algorithm, but rather ensures signal transmission. Area division reduces indoor transmitter power consumption and avoids interference from pseudo-GNSS signals received by users in different locations. When a user moves from one area to another, the main control unit controls the beam direction of the indoor transmitter to transmit pseudo-GNSS signals towards the area where the user's receiver is located.

[0058] This invention allows an indoor transmitter to emit pseudo-GNSS signals when a user moves indoors, enabling the satellite system to calculate the user's location. When a user enters the room from outdoors, since the visible satellites are the same for the user's receiver, the indoor receiver emits a modified pseudorange signal from the visible satellites, allowing the user receiver to achieve seamless positioning.

[0059] Simulation Examples

[0060] The simulation results for the pseudorange modification method are as follows:

[0061] The position information of the received raw GNSS signal is calculated as follows: Figure 1 As shown. From Figure 1 It can be seen that 6 satellites can be captured, and the original positioning results are latitude 34°15`33.3894`` and longitude 108°38`53.0962``.

[0062] By modifying the C / A code phase, the propagation time between the outdoor receiver's reception time and the satellite's transmission time is altered, thus achieving pseudorange modification and increasing the longitude by one second. The positioning program then recalculates the positioning location (e.g., ...). Figure 2 As shown): The positioning result is latitude 34°15`33.3822`` and longitude 108°38`54.1033``. Compared with the original signal result, the longitude was increased by one second, and the modification was successful.

[0063] The pseudorange is corrected again, increasing the longitude by one minute and decreasing the latitude by one minute, and the location is redefined (e.g., Figure 3 As shown): The result is latitude 34°14`33.2492``, longitude 108°39`53.1731``, the modification was successful.

[0064] The simulation results demonstrate the effectiveness of the pseudorange modification method of the present invention.

Claims

1. An indoor positioning system based on pseudosatellites, characterized in that, include: An outdoor receiver, an indoor transmitter, and a main control unit; the indoor transmitter's signal coverage area within the room is divided into multiple transmission zones; An outdoor receiver is used to receive GNSS signals from visible satellites and send the GNSS signals to the main control unit. The main control unit is used to receive GNSS signals sent by the outdoor receiver, calculate the location information of the outdoor receiver based on the received GNSS signals, and modify the pseudorange of the calculated location information by modifying the C / A code phase based on the location information of the transmission area and the location information of the outdoor receiver, so as to obtain a pseudo GNSS signal corresponding to the transmission area and send it to the indoor transmitter. Used to control the beam direction of the indoor transmitter; The indoor transmitter is used to receive pseudo GNSS signals sent by the master control unit and, under the control of the master control unit, transmit pseudo GNSS signals to the corresponding transmission area. The indoor transmission area is pre-divided and stored in the main control terminal. The main control terminal controls the indoor transmitter to transmit pseudo GNSS signals into the indoor area. The indoor transmitter is a multi-antenna transmitter composed of an antenna array. When the indoor transmitter transmits pseudo GNSS signals, it transmits to the transmission area where the user receiver is located under the control of the main control terminal. When a user moves indoors, the indoor transmitter selectively transmits signals to areas where user receivers are located. When there are no users in a certain area, the transmitter stops transmitting signals to that area. The user receiver is a receiver capable of processing GNSS signals.

2. The pseudo-satellite-based indoor positioning system according to claim 1, characterized in that, The outdoor receiver is a GNSS receiver.

3. The pseudo-satellite-based indoor positioning system according to claim 1, characterized in that, The main control unit includes a GNSS calculation module, a pseudorange modification module, and a transmission control module; The GNSS resolution module is used to calculate the location information of the outdoor receiver based on the received GNSS signals. The pseudorange modification module modifies the calculated position information by modifying the C / A code phase based on the location information of the transmitting area and the location information of the outdoor receiver, and reconstructs it into a pseudo GNSS signal corresponding to the transmitting area. The transmission control module is used to control the beam direction of the indoor transmitter, enabling the indoor transmitter to transmit pseudo-GNSS signals to the corresponding transmission area.

4. The pseudo-satellite-based indoor positioning system according to claim 1, characterized in that, Several indoor transmitters are set up, and the transmission signal coverage of each indoor transmitter is different.

5. An indoor positioning method based on pseudosatellites, characterized in that, The system based on claim 1 includes: Step 1: The outdoor receiver receives GNSS signals from visible satellites and sends the GNSS signals to the main control unit; Step 2: The main control unit receives the GNSS signal sent by the outdoor receiver and calculates the location information of the outdoor receiver. Step 3: Based on the location information of the transmission area and the location information of the outdoor receiver, the main control terminal modifies the pseudorange of the calculated outdoor receiver location information by modifying the C / A code phase, obtains the pseudo GNSS signal corresponding to the transmission area, and sends it to the indoor transmitter. Step 4: The indoor transmitter receives the pseudo GNSS signal, and the main control unit controls the beam direction of the indoor transmitter so that the indoor transmitter transmits the pseudo GNSS signal to the corresponding transmission area; the user receiver is a receiver capable of resolving GNSS signals. Step 5: The user receiver receives the pseudo GNSS signal and calculates the user receiver's position information based on the pseudo GNSS signal.

6. The indoor positioning method based on pseudosatellites according to claim 5, characterized in that, In step 1, the outdoor receiver amplifies the received GNSS signal and sends it to the main control terminal as an analog signal.

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