Method for generating and broadcasting messages for low earth orbit satellites

Abstract

Provided are a low-orbit satellite message generation and broadcasting method, a terminal device positioning method, a low-orbit satellite, a low-orbit navigation enhancement system, a terminal device, and a non-transitory computer readable storage medium. The low-orbit satellite message generation and broadcasting method includes the steps of: receiving a complete navigation enhancement message of a GNSS satellite and a low-orbit satellite navigation message, the complete navigation enhancement message and the low-orbit satellite navigation message being generated by a control center according to monitoring data obtained by a space-borne monitoring receiver and a ground-based monitoring receiver; and broadcasting the complete navigation enhancement message of a visible GNSS satellite of the low-orbit satellite, the low-orbit satellite navigation message, and a ranging signal of the low-orbit satellite to a user terminal. The low-orbit satellite message generation and broadcasting method can significantly improve the use efficiency of broadcast channel broadcasting resources, and the complete navigation enhancement message does not need to be used in matching with a basic navigation message of a GNSS.

Description

Technical Field

[0001] This disclosure relates to the field of satellite navigation, and specifically to methods for generating and broadcasting messages for low-Earth orbit (LEO) satellites, positioning methods for terminal equipment, LEO satellites, LEO navigation augmentation systems, terminal equipment, and computer-readable storage media. Background Technology

[0002] For GNSS (Global Navigation Satellite System), the normal broadcasting of navigation service signals and basic navigation messages is a necessary condition for the GNSS system to provide normal services.

[0003] Existing satellite navigation augmentation systems can generate more accurate correction parameters (i.e., navigation augmentation messages) relative to the basic GNSS navigation message and broadcast them to users within a specific service area to further improve the accuracy and integrity of GNSS services. The navigation augmentation message is a correction relative to the basic GNSS navigation message; therefore, users must obtain both the basic GNSS navigation message and the navigation augmentation message to use them correctly.

[0004] Existing satellite navigation augmentation systems generate correction parameters based on the basic GNSS navigation message. However, the methods and time required for users to receive the latest basic GNSS navigation message and the latest navigation augmentation message are not consistent, and the times at which users and ground-based augmentation monitoring and processing systems receive navigation messages also differ slightly. Therefore, matching the basic GNSS navigation message and the navigation augmentation message is very troublesome, and there is a risk of short-term mismatch or inability to match data version numbers.

[0005] Furthermore, existing satellite navigation augmentation systems employ a homogeneous broadcasting strategy to transmit navigation augmentation messages from all GNSS satellites across the entire service area. As the number of GNSS systems, the total number of satellites, the number of signals, and the broadcasting parameters increase, broadcasting navigation augmentation messages from all GNSS satellites across the entire service area will place increasing pressure on existing satellite navigation augmentation systems. Moreover, the homogeneous broadcasting strategy cannot account for the differences in observable GNSS satellite conditions among users at different specific locations within the service area. Summary of the Invention

[0006] Providing a mechanism to alleviate, reduce or eliminate at least one of the above problems would be beneficial.

[0007] In a first aspect, a method for generating and broadcasting messages from low-Earth orbit (LEO) satellites is provided. This method includes the steps of: receiving a complete navigation enhancement message from a GNSS satellite and a LEO satellite navigation message, wherein the complete navigation enhancement message and the LEO satellite navigation message are generated by an operations control center based on monitoring data acquired by a spaceborne monitoring receiver and a ground-based monitoring receiver; and broadcasting the complete navigation enhancement message, the LEO satellite navigation message, and the ranging signal of the LEO satellite from a visible GNSS satellite to a user terminal.

[0008] In a second aspect, a positioning method for a terminal device is provided. The method includes the following steps: receiving complete navigation enhancement messages from multiple low-Earth orbit (LEO) satellites, LEO satellite navigation messages, and ranging signals from the LEO satellites; and determining the PVT information of the terminal device based on the ranging signals from the GNSS satellites, the complete navigation enhancement messages from the GNSS satellites, the LEO satellite navigation messages, and the LEO satellite ranging signals.

[0009] In a third aspect, a low-Earth orbit (LEO) satellite is provided. The LEO satellite includes: one or more processors; and one or more memories coupled to the one or more processors and storing instructions thereon, which, when executed individually or jointly by the one or more processors, cause the LEO satellite to perform the aforementioned LEO satellite message generation and broadcasting method.

[0010] In the fourth aspect, a low-Earth orbit (LEO) navigation enhancement system is provided. This LEO navigation enhancement system includes the aforementioned multiple LEO satellites.

[0011] In a fifth aspect, a terminal device is provided. The terminal device includes: one or more processors; and one or more memories coupled to the one or more processors and storing instructions thereon. When the instructions are executed individually or jointly by the one or more processors, the terminal device performs the aforementioned terminal positioning method.

[0012] In a sixth aspect, a non-transitory computer-readable storage medium is provided that stores machine-executable instructions. When executed by one or more processors of a machine, the machine-executable instructions cause the machine to perform the aforementioned method for generating and broadcasting messages for low-Earth orbit satellites.

[0013] In a seventh aspect, a non-transitory computer-readable storage medium is provided that stores machine-executable instructions. When executed by one or more processors of a machine, the machine-executable instructions cause the machine to perform the aforementioned positioning method for a terminal device.

[0014] It should be understood that the summary section is not intended to identify key or essential features of the embodiments of this disclosure, nor is it intended to limit the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0015] The above and other objects, features, and advantages of this disclosure will become more apparent from the more detailed description of some embodiments thereof in the accompanying drawings, in which:

[0016] Figure 1 A schematic diagram of the implementation environment of a low-Earth orbit satellite provided according to an embodiment of the present disclosure is shown;

[0017] Figure 2 A flowchart is shown of a method for generating and broadcasting messages for low-Earth orbit satellites according to embodiments of the present disclosure;

[0018] Figure 3 A flowchart of a positioning method for a terminal device provided according to an embodiment of the present disclosure is shown;

[0019] Figure 4 A simplified block diagram of a low-Earth orbit satellite provided according to some embodiments of the present disclosure is shown; and

[0020] Figure 5 A simplified block diagram of a terminal device provided according to some embodiments of the present disclosure is shown. Detailed Implementation

[0021] The principles of this disclosure will now be described with reference to some embodiments. It should be understood that these embodiments are described for illustrative purposes only and to assist those skilled in the art in understanding and implementing this disclosure, and do not impose any limitation on the scope of this disclosure. The disclosure described herein may be implemented in ways other than those described below.

[0022] In the following description and claims, 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 this disclosure pertains.

[0023] References to "an embodiment," "embodiment," "exemplary embodiment," etc., in this disclosure indicate that the described embodiments may include specific features, structures, or characteristics, but not every embodiment needs to include specific features, structures, or characteristics. Furthermore, such phrases do not necessarily refer to the same embodiment. Moreover, when a specific feature, structure, or characteristic is described in connection with an exemplary embodiment, whether explicitly described or not, those skilled in the art will recognize that such a feature, structure, or characteristic affects its connection to other embodiments.

[0024] It should be understood that while the terms “first” and “second”, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, without departing from the scope of the exemplary embodiments, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. The term “and / or” as used herein includes any and all combinations of one or more of the listed terms.

[0025] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments. The singular forms “a,” “an,” and “the” used herein also include the plural forms unless the context clearly indicates otherwise. The terms “a group of elements” or “a collection of elements” as used herein are intended to include one or more elements. It should also be understood that the terms “comprising,” “including,” “having,” “possessing,” “including,” and / or “comprising,” when used herein, specify the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof.

[0026] The term "terminal device" refers to any terminal device capable of wireless communication. As an example and not a limitation, a terminal device may also be referred to as a communication device, user equipment (UE), subscriber station (SS), portable subscriber station, mobile station (MS), or access terminal (AT). This terminal device may include, but is not limited to, mobile phones, cellular phones, smartphones, Voice over IP (VoIP) phones, wireless local loop phones, tablets, wearable terminal devices, personal digital assistants (PDAs), portable computers, desktop computers, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback devices, in-vehicle wireless terminal devices, wireless endpoints, mobile stations, laptop embedded devices (LEE), laptop installed devices (LME), USB dongles, smart devices, wireless subscriber equipment (CPE), Internet of Things (IoT) devices, watches or other wearable devices, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in the context of industrial and / or automated processing chains), consumer electronics devices, relay nodes, devices operating on commercial and / or industrial wireless networks, etc. The mobile terminal (MT) portion of an IAB node can perform the functions of a "terminal device" and therefore can operate as a terminal device. In the following description, the terms "terminal device," "communication device," "terminal," "user terminal," and "UE" are used interchangeably.

[0027] While the functions described herein may be implemented in fixed and / or wireless network nodes in various exemplary embodiments, in other exemplary embodiments, they may be implemented in user equipment devices (such as cellular phones, tablet computers, laptop computers, desktop computers, mobile IoT devices, or fixed IoT devices). For example, the user equipment device may suitably have the corresponding capabilities described in relation to fixed and / or wireless network nodes. The user equipment device may be user equipment and / or control devices, such as chipsets or processors, configured to control the user equipment when it is installed therein. Examples of these functions include boot server functions and / or home subscriber servers, which may be implemented in the user equipment device by providing the user equipment device with software configured to cause the user equipment device to perform from the perspective of these functions / nodes.

[0028] As mentioned above, existing satellite navigation augmentation systems employ a homogeneous broadcasting strategy to transmit navigation augmentation messages from all GNSS satellites across the entire service area. However, this method cannot account for the differences in observable GNSS satellite conditions among users at different specific locations within the service area. Furthermore, the navigation augmentation messages broadcast by existing satellite navigation augmentation systems must be matched with the basic GNSS navigation messages. Matching the basic GNSS navigation messages and navigation augmentation messages is cumbersome and carries the risk of short-term mismatches or incompatibility in data version numbers.

[0029] The message generation and broadcasting method for low-Earth orbit satellites provided in the embodiments of this disclosure can broadcast complete navigation enhancement messages of visible GNSS satellites in a targeted manner, significantly improving the utilization efficiency of navigation broadcast channel broadcasting resources. Furthermore, the complete navigation enhancement messages do not need to be matched with the basic navigation messages of GNSS, thereby reducing the coupling and risks caused by matching.

[0030] Navigation users need to determine the terminal's PVT information based on the ranging signals from navigation satellites and navigation message information. PVT information consists of position, velocity, and time. By observing the ranging signals of multiple navigation satellites, navigation users can obtain satellite observation information such as pseudorange, phase, and Doppler. Based on the navigation message information, navigation users can obtain information used to calculate PVT, including satellite position, satellite clock bias, ionospheric delay correction information, and integrity information.

[0031] The GNSS system collects GNSS satellite navigation signals through ground monitoring stations, forms monitoring data, and sends it to the ground operation control center to obtain the basic GNSS navigation message.

[0032] However, due to factors such as satellite navigation errors and user location, relying solely on GNSS cannot achieve ideal navigation and positioning results. To further improve the accuracy and integrity of navigation services, satellite navigation augmentation systems have emerged.

[0033] However, existing satellite navigation augmentation systems cannot directly control or transmit messages to GNSS satellites. Therefore, they independently use other GEO (Geostationary Earth Orbit) communication satellites to broadcast navigation augmentation messages. To conserve link resources, navigation augmentation messages need to express correction information in the form of correction numbers relative to the basic GNSS navigation message.

[0034] Since the correction information included in the navigation enhancement message is a correction relative to the basic navigation message, the user must obtain both the basic GNSS navigation message and the navigation enhancement message from the satellite navigation enhancement system in order to calculate the PVT information.

[0035] Furthermore, the existing satellite navigation enhancement message broadcasting mode based on basic navigation messages and navigation enhancement messages is quite cumbersome to use. The corrections for the ephemeris parameters in the navigation enhancement message are expressed using radial (R), tangential (T), and normal (N) corrections. When calculating the PVT, users need to convert the correction parameters in the RTN orbital coordinate system to the Cartesian Earth-fixed rectangular coordinate system and then match them with the satellite position coordinates calculated from the basic navigation message, making the calculation process very complicated.

[0036] Furthermore, the methods and time required for users to receive the latest basic navigation messages and the latest navigation enhancement messages are not consistent, and they also differ from the reception time of the ground-based enhancement monitoring and processing system. This leads to a risk of short-term mismatch or inability to match data version numbers, especially before and after updates to the basic navigation messages.

[0037] Please refer to Figure 1 , Figure 2 and Figure 3 , Figure 1 A schematic diagram illustrating message generation and broadcasting of a low-Earth orbit satellite according to an embodiment of the present disclosure is shown. Figure 2 A flowchart illustrating a method for generating and broadcasting messages for low-Earth orbit satellites according to embodiments of the present disclosure is shown. Figure 3 A flowchart of a positioning method for a terminal device provided according to an embodiment of the present disclosure is shown.

[0038] The following will refer to Figure 1 , Figure 2 and Figure 3 The principles and implementation of this disclosure are described in detail.

[0039] The low-Earth orbit (LEO) navigation enhancement system 100 provided in the embodiments of this disclosure can be a communication-navigation integrated LEO navigation enhancement system. A communication-navigation integrated LEO navigation enhancement system is a system that integrates communication and navigation functions, utilizing a LEO satellite constellation to provide navigation enhancement services. The LEO navigation enhancement system 100 includes multiple LEO satellites 110, an operations control center 120, and monitoring receivers 130. In one example, the monitoring receivers 130 include a space-based GNSS monitoring receiver 131 and a ground-based monitoring receiver 132 mounted on the LEO satellites 110. Each LEO satellite 110 is communicatively connected to one or more user terminals 200 below it, and communication with the user terminals 200 is achieved through the broadcast channels and / or communication service channels of the LEO satellites 110.

[0040] The low-Earth orbit (LEO) navigation augmentation system 100 can acquire monitoring data through the monitoring receiver 130. The LEO navigation augmentation system 100 can acquire better and more complete monitoring data through the spaceborne monitoring receiver 131 on the LEO satellite 110 and the established, regionally independent, larger-scale, and higher-density ground-based monitoring receivers 132 for monitoring, communication, processing, and broadcasting. This monitoring data includes better and more complete GNSS monitoring data. The acquired GNSS monitoring data can improve the positioning accuracy of the GNSS system, providing a foundation for subsequently generating higher-precision and more complete navigation augmentation messages. Here, the spaceborne monitoring receiver 131 on the LEO satellite 110 can be a space-based GNSS monitoring receiver.

[0041] Specifically, GNSS monitoring data is acquired by multiple low-Earth orbit (LEO) satellites, via onboard monitoring receivers 131 and ground-based monitoring receivers 132, and then transmitted to the operation and control center 120. The ground-based monitoring receiver 101 of the LEO navigation augmentation system 100 can also acquire LEO satellite monitoring data that is consistent with the GNSS monitoring data benchmark and transmit it to the operation and control center 120.

[0042] Based on the monitoring data acquired by the onboard monitoring receiver 131 and the ground-based monitoring receiver 132, the operation control center 120 generates a complete navigation enhancement message for the GNSS satellite and a low-orbit satellite navigation message for the low-orbit satellite itself.

[0043] The complete navigation enhancement message of a GNSS satellite differs from the navigation enhancement message broadcast by existing satellite navigation enhancement systems. The navigation enhancement message broadcast by existing satellite navigation enhancement systems is expressed using corrections relative to the basic GNSS navigation message. The complete navigation enhancement message includes all GNSS message information (referred to here as full elements), which may specifically include ephemeris parameters, clock error parameters, almanac parameters, ionospheric delay correction parameters, integrity information, and satellite constellation delay parameters.

[0044] Specifically, based on GNSS monitoring data and low-orbit satellite monitoring data, the Operations Control Center 120 can independently generate more accurate and complete GNSS satellite navigation enhancement messages and low-orbit satellite navigation messages that are more accurate and complete than the basic GNSS navigation messages, through processes such as orbit determination and prediction, satellite clock bias determination and prediction, ionospheric delay detection and modeling, and integrity processing.

[0045] Furthermore, based on the onboard monitoring receiver 131 equipped on the low-Earth orbit satellite 110, the complete navigation enhancement message of the GNSS satellite and the low-Earth orbit satellite navigation message include integrity information of GNSS signals and messages monitored based on the global seamless multi-satellite platform. Here, the global seamless multi-satellite platform is a comprehensive space infrastructure platform with multiple functions, constructed using multiple satellites to achieve seamless global coverage.

[0046] A complete navigation enhancement message from a full-element GNSS satellite can be used independently without matching it with the basic GNSS navigation message. When using the navigation service, the user terminal 200 no longer needs to receive the basic GNSS navigation message, thereby reducing the coupling of the navigation service and effectively improving its availability.

[0047] After the operations control center 120 generates complete navigation enhancement messages for GNSS satellites and navigation messages for LEO satellites, the LEO navigation enhancement system 100 injects the generated complete navigation enhancement messages for GNSS satellites and navigation messages for LEO satellites into each LEO satellite 110. Here, the LEO navigation enhancement system injects messages at a higher frequency than GNSS and existing satellite navigation enhancement systems.

[0048] like Figure 2 As shown, from the perspective of the low-orbit satellite 110, it first performs step S21: receiving the complete navigation enhancement message and the low-orbit satellite navigation message from the GNSS satellite. The complete navigation enhancement message and the low-orbit satellite navigation message are generated by the operation and control center 120 based on the monitoring data obtained by the onboard monitoring receiver 131 and the ground-based monitoring receiver 132.

[0049] Next, the low-orbit satellite 110 executes step S22: broadcasting the complete navigation enhancement message of the visible GNSS satellite, the low-orbit satellite navigation message, and the low-orbit satellite ranging signal to the user terminal.

[0050] After the complete navigation enhancement message of the GNSS satellite and the low-Earth orbit satellite navigation message are uploaded to the low-Earth orbit satellite 110, they can be broadcast directly to users by the low-Earth orbit satellite 110 through the broadcast channel.

[0051] The low-Earth orbit (LEO) satellite 110 has a low orbital altitude, and its visible GNSS satellite conditions are highly correlated with those of the ground-based user terminals 200 in the area where the LEO satellite 110 is located. When the ground-based user terminals 200 calculate PVT information, information from other GNSS satellites outside of the visible GNSS satellite conditions is redundant. Therefore, each LEO satellite 110 can broadcast only the complete navigation enhancement message from GNSS satellites with higher visible elevation angles, reducing the broadcast of invalid information. This ensures that the information received by the ground-based user terminals 200 below each LEO satellite 110 is comprehensive and without redundancy, improving the efficiency of the broadcast channel.

[0052] like Figure 3 As shown, from the user terminal 200 side, its execution step S31 is: receiving the complete navigation enhancement message of the GNSS satellite, the low-orbit satellite navigation message and the low-orbit satellite ranging signal broadcast by multiple low-orbit satellites 110;

[0053] Then, step S32 is executed: based on the ranging signal from the GNSS satellite, the complete navigation enhancement message from the GNSS satellite, the navigation message from the low-Earth orbit satellite, and the ranging signal from the low-Earth orbit satellite, the PVT information of the terminal equipment is determined.

[0054] Specifically, GNSS satellite observations can be determined using ranging signals from GNSS satellites. In some embodiments, the user terminal 200 may also selectively receive GNSS pilot branch measurement signals without receiving GNSS data branch signals to obtain the basic GNSS navigation message.

[0055] User terminal 200 can obtain GNSS navigation enhancement services and GNSS integrity enhancement services simply by receiving GNSS ranging signals and the complete navigation enhancement message broadcast by low-orbit satellite 110, decoupling it from the original GNSS basic navigation message. Understandably, regardless of whether the original GNSS ground control or basic navigation message is normal or intact, as long as the quality of the broadcast navigation ranging signals is normal, user terminal 200 can obtain the complete enhancement service.

[0056] Furthermore, the user terminal 200 obtains GNSS navigation observations and LEO satellite observations through the ranging signals of GNSS satellites and LEO satellites 110. Combined with the complete navigation enhancement message and LEO satellite navigation message, it can obtain better PVT information services.

[0057] The positioning accuracy of user terminal 200 is related to the user's equivalent ranging accuracy and the position dilution of precision (PDOP). The PDOP is determined by the constellation geometry. The more satellite signals received by user terminal 200 (e.g., ranging signals broadcast by multiple low-Earth orbit satellites and / or ranging signals from multiple GNSS satellites), the wider the distribution range of satellites in the field of view of user terminal 200, and the larger the volume formed by the satellite lines. Correspondingly, the value of the PDOP is smaller. Therefore, in addition to receiving the complete navigation enhancement message and ranging signals from GNSS satellites, user terminal 200 also receives the ranging signals and low-Earth orbit navigation messages from low-Earth orbit satellite 110 itself. This allows it to acquire more observations for PVT calculation, reduce the PDOP, and improve the positioning accuracy of user terminal 200.

[0058] For example, to achieve decimeter-level positioning accuracy, relying solely on GNSS satellites might take about ten minutes. However, by combining the GNSS ranging signals from high-orbit or medium-orbit satellites with the complete GNSS navigation enhancement message transmitted by the low-orbit satellite 110, the ranging signal from the low-orbit satellite 110, and the low-orbit satellite navigation message of the low-orbit satellite 110 itself, the convergence time to achieve decimeter-level positioning accuracy can be shortened to about one minute, thereby greatly accelerating the convergence time.

[0059] The low-Earth orbit (LEO) navigation augmentation system 100 injects messages at a higher frequency than GNSS and existing satellite navigation augmentation systems. In some embodiments, the LEO navigation augmentation system 100 can inject messages at a rate on the order of seconds.

[0060] GNSS basic navigation messages typically employ a fixed-period, fixed-time, and fixed-format injection method on an hourly basis. This injection mode lacks flexibility and cannot be dynamically adjusted according to real-time needs and circumstances, resulting in low overall utilization efficiency of injection and broadcast resources. Furthermore, the longer the injection period, the older the data in the basic navigation messages used by users will be, potentially introducing larger ephemeris and clock prediction errors, directly impacting navigation service performance. In addition, the fixed and publicly available signal system is also detrimental to ensuring the security of navigation services, such as resistance to spoofing.

[0061] The total amount of navigation enhancement messages to be broadcast by existing satellite navigation enhancement systems increases with the number of GNSS satellites, and the broadcasting cycle is long, resulting in some satellite navigation enhancement messages having a long data age, which reduces the effectiveness of navigation enhancement messages.

[0062] The low-orbit navigation augmentation system 100 provided in the embodiments of this disclosure can perform message injection at a second-level cycle. The frequency of message injection is much higher than that of GNSS or existing satellite navigation augmentation systems, which greatly reduces parameter prediction errors and enables higher frequency message updates and broadcasts.

[0063] Since the frequency of message transmission on the low-Earth orbit navigation augmentation system 100 is higher than that of GNSS and existing satellite navigation augmentation systems, the low-Earth orbit navigation augmentation system 100 can use simpler ephemeris parameters and clock bias parameters to accurately express the complete navigation augmentation message.

[0064] The complete navigation enhancement message generated by the low-Earth orbit navigation enhancement system 100 can represent the GNSS satellite orbit using an ephemeris model with fewer parameters. In some embodiments, the ephemeris parameters of the message can be determined based on a Kepler 10-parameter ephemeris model.

[0065] The usable arc length of a GNSS system needs to be greater than 1-2 hours; therefore, the ephemeris model used by GNSS systems has a large number of parameters. GNSS systems generally use the Kepler 16-parameter ephemeris model to represent GNSS satellite orbits. The 16-parameter ephemeris model is more complex and computationally intensive than the 10-parameter ephemeris model.

[0066] Because the low-orbit navigation enhancement system 100 provided in the embodiments of this disclosure maintains a high-speed connection with the ground station and the message is updated frequently, the observable arc of the low-orbit navigation enhancement system 100 is short, and the usable arc length is only tens of seconds. Therefore, the complete navigation enhancement message can use an ephemeris model with fewer parameters to express the GNSS satellite orbit.

[0067] In some embodiments of this disclosure, the ephemeris parameters of the complete navigation enhancement message can be expressed with millimeter-level precision within minute-level available arc segments based on a Kepler 10-parameter ephemeris model. As shown in Table 1:

[0068]

[0069] Table 1

[0070] The parameters of the Kepler 10-parameter ephemeris model can include ephemeris reference time. The approximate angle at the reference time eccentricity , reference time semi-major axis square root Track inclination Variable rate of tilt angle Longitude of the ascending node at the reference time Angular distance from perigee Sine harmonic coefficient of latitude argument and the cosine harmonic coefficient of the latitudinal argument The data size of a complete navigation enhancement message for GNSS generated using the Kepler 10-parameter ephemeris model is approximately 286 bits per satellite when broadcast.

[0071] The Low Earth Orbit (LEO) navigation augmentation system 100 can select 10-parameter GNSS satellite orbits with an arc length of 1 minute for fitting experiments. Fitting of 10-parameter ephemeris was performed using BeiDou IGSO (Inclined Geosynchronous Orbit) satellites, BeiDou MEO (Medium Earth Orbit) satellites, and GPS (Global Positioning System) MEO satellites. The statistical accuracy of the fitted three-dimensional position was better than 1 cm.

[0072] The truncation error in the 16-parameter ephemeris model used in existing GNSS systems results in ephemeris position errors reaching the decimeter level, with a maximum error of approximately 0.5 meters. For navigation services supporting high-precision GNSS applications, this error is significant and cannot be ignored. However, the Low Earth Orbit Navigation Augmentation System 100, using a 10-parameter ephemeris model, can improve the accuracy of the final three-dimensional position representation of BeiDou IGSO navigation satellites, BeiDou MEO satellites, and GPS MEO satellites from the original decimeter level to approximately 1 cm, fully meeting the requirements for message generation, representation, and application.

[0073] Furthermore, the basic navigation message generated by the GNSS system using the Kepler 16-parameter ephemeris model has a broadcast data size of approximately 367 bits / satellite. Based on this basic navigation message, the navigation enhancement message (i.e., correction) generated by existing satellite navigation enhancement systems has a data size of approximately 69 bits / satellite. The complete navigation enhancement message generated by the low-Earth orbit navigation enhancement system 100 provided in the embodiments of this disclosure has a broadcast data size of approximately 286 bits / satellite. Compared to the scenario where users use both basic and navigation enhancement messages, the complete navigation enhancement message provided in the embodiments of this disclosure can save 150 bits / satellite.

[0074] Furthermore, since the LEO navigation augmentation system 100 broadcasts a complete navigation augmentation message including a complete and precise orbital ephemeris, it does not need to perform correction calculations before broadcasting, nor does it need to broadcast the data version number and two sets of parameter integrity information used to support the basic navigation message and correction parameter matching for GNSS. As a result, the complete navigation augmentation message broadcast by the LEO satellite 110 can compress the total amount of ephemeris information by nearly 50%, improve the utilization efficiency of valuable broadcast channel broadcast link resources, and significantly simplify the user's algorithm.

[0075] Similarly, given the high frequency of message transmission by the LEO navigation augmentation system 100 and the shorter transmission cycle of the LEO satellite 110, the LEO navigation augmentation system 100 can independently achieve high-precision clock error prediction using only a linear clock error model. Compared to existing quadratic term models and the combined models of existing navigation augmentation systems based on message clock error parameters and navigation augmentation message clock error correction parameters, the LEO navigation augmentation system 100 simplifies the message parameter model while achieving high-precision clock error prediction.

[0076] Therefore, the complete navigation enhancement message generated by the LEO navigation enhancement system 100, by adopting simpler ephemeris and clock bias parameters, significantly simplifies the message parameter model while ensuring the accuracy of the ephemeris and clock bias parameters, reduces the total amount of message information, further shortens the injection cycle, and reduces forecast errors. Thus, while saving link resources, it fully leverages the advantage of short message injection cycle, providing strong support for continuous high-frequency message injection, updating, and broadcasting, forming a virtuous cycle, improving the real-time performance and bandwidth utilization of two-way interaction between LEO satellite 110 and ground data, improving message reception and usage efficiency, and enhancing the accuracy and integrity of user services.

[0077] Due to the short observable arc and large number of low-Earth orbit (LEO) satellites 110, the message broadcasting strategy of the LEO navigation augmentation system 100 significantly affects the user experience. In some embodiments, the LEO navigation augmentation system 100 can further improve message usage efficiency through differentiated message broadcasting methods.

[0078] Existing satellite navigation augmentation systems use signals from multiple GEO satellites to broadcast navigation augmentation messages from all GNSS satellites within the service area in a fixed format, using the same method and serial order. Broadcasting through multiple GEO satellites expands the overall service coverage and improves the reliability of user reception within overlapping signal ranges through redundancy. For example, if there are 10 GNSS satellites, the current system uses signals from two GEO satellites to broadcast navigation augmentation messages from GNSS satellites 1 through 10 in a fixed format and serial order. However, as the number of GNSS satellites increases, this homogeneous broadcasting strategy will face increasing pressure, and its message utilization efficiency is very low.

[0079] The low-Earth orbit navigation enhancement system 100 provided in the embodiments of this disclosure includes multiple low-Earth orbit satellites 110. Low-Earth orbit satellites 110 adjacent to each other in the same orbit or low-Earth orbit satellites 110 in the same phase in adjacent orbits can broadcast the complete navigation enhancement messages of each visible GNSS satellite in a differentiated and parallel manner according to the positions of multiple visible GNSS satellites and in different orders, based on the number and configuration characteristics of the low-Earth orbit constellation satellites, in order to adapt to the increasing demand for GNSS satellites and enhancement elements.

[0080] In some embodiments, low-Earth orbit satellites 110 in the same orbit or low-Earth orbit satellites 110 in adjacent orbits and in phase can broadcast the complete navigation enhancement messages of each visible GNSS satellite in parallel in reverse order, based on the positions of multiple visible GNSS satellites.

[0081] For example, two adjacent low-Earth orbit (LEO) satellites 110 can be designated as the first LEO satellite and the second LEO satellite. There are a total of 10 visible GNSS satellites associated with these two adjacent LEO satellites 110. For ease of understanding, they are numbered according to their positional order. Based on the positions of these visible GNSS satellites, the first LEO satellite can broadcast the complete navigation enhancement messages of GNSS satellites 1 through 10 in ascending order. The second LEO satellite can broadcast the complete navigation enhancement messages of GNSS satellites 10 through 1 in reverse order.

[0082] By broadcasting complete navigation enhancement messages in a differentiated parallel manner using the first and second LEO satellites, the user terminal 200 can simultaneously receive complete navigation enhancement messages from multiple different GNSS satellites, significantly reducing the time required to receive complete navigation enhancement messages from all GNSS satellites. In this example, the time required for the user terminal 200 to receive complete navigation enhancement messages from all GNSS satellites is half that of the case where messages are broadcast sequentially.

[0083] Thus, compared to a homogeneous broadcasting strategy, broadcasting complete navigation enhancement messages in parallel in different orders can significantly reduce the time required to collect complete navigation enhancement messages from all GNSS satellites while achieving redundancy backup. This further improves the efficiency of user terminals 200 in receiving complete navigation enhancement messages, and enhances the efficiency of message usage and broadcast channel usage.

[0084] Additionally, the low-Earth orbit satellite 110 can broadcast satellite almanacs in a differentiated manner. In some embodiments, each low-Earth orbit satellite 110 can determine the almanac parameters for the broadcast complete navigation enhancement message based on the grouping of satellites by orbital altitude, orbital parity, and / or phase parity.

[0085] In existing GNSS systems, each satellite needs to broadcast almanac information for the entire constellation to support user terminals in quickly acquiring satellite signals after power-on. However, with a large number of low-Earth orbit (LEO) satellites, broadcasting the entire constellation almanac from each LEO satellite is inefficient. Therefore, while improving the reliability of broadcasting complete navigation enhancement messages for the LEO navigation augmentation system 100, the large number of LEO satellites also places a burden on the initial acquisition of LEO satellite signals.

[0086] Therefore, in some embodiments, for the broadcasting of LEO satellite almanacs, LEO satellite 110 can distinguish the groups of satellites based on orbital altitude, orbital parity, and / or phase parity, and broadcast LEO satellite almanacs in a differentiated manner, thereby greatly improving the efficiency of LEO satellite 110 in broadcasting LEO satellite almanacs.

[0087] For example, the low-Earth orbit navigation augmentation system 100 can broadcast satellite almanacs in groups and zones, using a method that separates altitude layers, orbital planes, and phases. In some embodiments, low-Earth orbit satellites 110 in odd-numbered orbits can broadcast satellite almanacs for even-numbered orbits, and vice versa. Alternatively, in other embodiments, satellite almanacs are transmitted according to their altitude layer. For example, a low-Earth orbit satellite 110 at an altitude of 1100 km broadcasts its own almanac, and a low-Earth orbit satellite 110 at an altitude of 1200 km broadcasts its own almanac. It should be understood that the embodiments disclosed herein are merely specific solutions for ease of implementation, and those skilled in the art can combine the methods of separating altitude layers, orbital planes, and phases based on the above concepts to achieve differentiated broadcasting of satellite almanacs.

[0088] The LOR navigation augmentation system 100 can provide navigation services without being limited by the service area.

[0089] Navigation users calculate PVT information based on satellite observations and navigation message information. However, regional atmospheric delay parameters, such as ionospheric delay correction parameters, included in the navigation message information are regional parameters and need to be obtained from ground monitoring stations in the target area.

[0090] However, large-scale, high-density deployment of ground monitoring stations can only be carried out uniformly within a specific region. Therefore, in the absence of atmospheric delay parameters outside the service area, existing navigation augmentation systems are typically unable to calculate PVT information for user terminals outside the service area.

[0091] For security reasons, existing navigation augmentation systems cannot directly deploy authorized signal monitoring stations outside the designated service area. For economic reasons, existing systems are also unlikely to broadcast augmentation service signals with only a very small number of authorized users over a large area using GEO satellites. Current systems can only provide navigation augmentation services based on the monitored authorized signals, targeting users within a specific range, by controlling beams and using customized signal and information systems. This type of navigation augmentation service is costly, cannot support user-defined augmentation information, cannot provide services outside the designated service area, and certainly cannot provide global navigation services.

[0092] In the embodiments provided in this disclosure, the low-Earth orbit (LEO) navigation augmentation system 100 can be a communication and navigation integrated LEO navigation augmentation system. The LEO navigation augmentation system 100 can access resources from a third-party independently constructed ground-based augmentation system located in the target area, thereby enabling the LEO satellite 110 to receive regionalized parameters generated by the ground-based augmentation system in the target area.

[0093] Then, in addition to broadcasting the complete navigation enhancement message generated by the local operation and control center 120 to the user terminals 200 in the target area, the low-Earth orbit satellite 110 can also broadcast the regionalized parameters generated by the ground-based augmentation system in the target area to the user terminals 200 in the target area through the communication service channel of the low-Earth orbit satellite 110, thereby customizing the navigation enhancement information and incorporating the regionalized parameters as part of the navigation enhancement information. Specifically, the regionalized parameters are generated by the ground-based augmentation system in the target area and broadcast by the communication service channel of the low-Earth orbit satellite 110, while the non-regional, global parameters are provided by the complete navigation enhancement message generated by the local operation and control center 120 and broadcast by the broadcast channel of the low-Earth orbit satellite 110. Here, ephemeris parameters, clock bias parameters, satellite constellation delay parameters, and integrity information are considered as non-regional, global parameters, and the performance of global parameters has a similar impact on global user services.

[0094] The regionalization parameter can be a regional atmospheric delay parameter. The low-orbit satellite 110 can obtain the regionalization parameter by receiving the navigation enhancement message that includes the regional atmospheric delay parameter, and can broadcast the regionalization parameter to the user terminal 200 by broadcasting the navigation enhancement message that includes the regional atmospheric delay parameter through the communication service channel.

[0095] Regionalized atmospheric delay parameters can include high-precision ionospheric delay correction parameters. Here, the LEO navigation augmentation system 100 can support high-precision application services based on GNSS, such as PPP (Precise Point Positioning) and PPP-RTK (Precise Point Positioning-Real-Time Kinematic).

[0096] Therefore, the LEO navigation enhancement system 100 can broadcast customized navigation enhancement information to authorized users in any region of the world based on the communication service channel that integrates navigation and communication.

[0097] The user terminal 200 in the target area can obtain the regionalized parameters generated by the ground-based augmentation system in the target area through the communication service channel of the low-Earth orbit satellite 110. Then, the user terminal 200 in the target area can combine the regionalized parameters obtained from the communication service channel with the GNSS satellite ranging signal, the complete navigation augmentation message of the GNSS satellite, the low-Earth orbit satellite navigation message, and the low-Earth orbit satellite ranging signal obtained from the broadcast channel to calculate the PVT information of the user terminal 200.

[0098] In this way, the low-Earth orbit satellite 110 can independently broadcast high-precision GNSS complete navigation enhancement messages generated by the local operation and control center 120, and can also provide navigation enhancement service resources for various target areas connected by the low-Earth orbit navigation enhancement system 100. By combining broadcast channels and communication service channels, it can broadcast to specific locations, thus overcoming the communication bottleneck outside the service area and expanding the service area. This allows it to play the role of a platform for high-precision global satellite navigation enhancement services, thereby providing flexible and customized navigation enhancement services covering the globe.

[0099] In summary, the low-Earth orbit (LEO) satellite message generation and broadcasting method provided in this disclosure fully leverages the high uplink frequency of LEO satellite messages, significantly improving the utilization efficiency of navigation channel broadcasting resources. It also reduces the coupling and risks inherent in existing GNSS navigation enhancement services due to different information sources, and the calculation process is simpler and more reliable. Furthermore, the LEO satellite message broadcasting method is based on targeted message broadcasting from visualized GNSS satellites, making message broadcasting more efficient and further reducing the total amount of information received by users, thus lessening the burden on users receiving LEO satellite signals.

[0100] In some embodiments, the message generation and broadcasting method for low-Earth orbit satellites provided in the first aspect of this disclosure can be implemented via the low-Earth orbit satellites provided in the third aspect of this disclosure. The low-Earth orbit satellites used to perform the various steps of the message generation and broadcasting method for low-Earth orbit satellites can be implemented in any suitable form.

[0101] The low-Earth orbit (LEO) navigation enhancement system provided in the fourth aspect of this disclosure may include multiple LEO satellites. This LEO navigation enhancement system can be implemented based on a space-based internet architecture.

[0102] Please refer to Figure 4 , Figure 4 A simplified block diagram of a low-Earth orbit (LEO) satellite according to some embodiments of the present disclosure is shown. The LEO satellite 400 may include one or more processors 410 and one or more memories 420 coupled to the processors 410. The memories 420 include, but are not limited to, the non-transitory computer-readable storage medium 421 described above in the sixth aspect of the present disclosure, which stores machine-executable instructions. The processor 410 is connected to the memory 420 and configured to execute the computer instructions stored in the memory 420 to implement the LEO satellite message generation and broadcasting method provided in the first aspect of the present disclosure.

[0103] In some embodiments, the positioning method for the terminal device provided in the second aspect of this disclosure can be implemented via the terminal device provided in the fourth aspect of this disclosure. The terminal device for performing the various steps of the positioning method for the terminal device can be implemented in any suitable form. For example, the terminal device can be implemented in a circuit or software module.

[0104] Please refer to Figure 5 , Figure 5 A simplified block diagram of a terminal device according to some embodiments of the present disclosure is shown. The terminal device 500 may include one or more processors 510 and one or more memories 520 coupled to the processors 510. The memories 520 include, but are not limited to, the non-transitory computer-readable storage medium 521 described above in the seventh aspect of the present disclosure, which stores machine-executable instructions thereon. The processor 510 is connected to the memory 520 and configured to execute the computer instructions stored on the memory 520 to implement the terminal positioning method provided in the second aspect of the present disclosure.

[0105] Although the methods described above are illustrated and depicted as a series of actions for the sake of simplicity, it should be understood and appreciated that these methods are not limited by the order of the actions, as some actions may occur in a different order and / or concurrently with other actions from the illustrations and descriptions herein or not illustrated and described herein but which may be understood by those skilled in the art, according to one or more embodiments.

[0106] Those skilled in the art will understand that information, signals, and data can be represented using any of a variety of different techniques and skills. For example, the data, instructions, commands, information, signals, bits, symbols, and chips described throughout the above can be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, light fields or optical particles, or any combination thereof.

[0107] Those skilled in the art will further appreciate that the various illustrative logic blocks, modules, circuits, and algorithm steps described in conjunction with the embodiments disclosed herein can be implemented as electronic hardware, computer software, or a combination of both. To clearly illustrate this hardware-software interchangeability, the various illustrative components, blocks, modules, circuits, and steps are described above in a generalized manner in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. Those skilled in the art may implement the described functionality in different ways for each particular application, but such implementation decisions should not be construed as departing from the scope of this disclosure.

[0108] The various illustrative logic modules and circuits described in conjunction with the embodiments disclosed herein may be implemented or performed using a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. The general-purpose processor may be a microprocessor, but in alternatives, it may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors cooperating with a DSP core, or any other such configuration.

[0109] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of both. The software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor such that the processor can read and write information to / from the storage medium. In an alternative, the storage medium may be integrated into the processor. The processor and storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In an alternative, the processor and storage medium may reside as discrete components in the user terminal.

[0110] The prior description of this disclosure is provided to enable any person skilled in the art to make or use this disclosure. Various modifications to this disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not intended to be limited to the examples and designs described herein, but should be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for generating and broadcasting a low earth orbit satellite's ephemeris, characterized by, Including the following steps: The system receives complete navigation enhancement messages from GNSS satellites and navigation messages from low-Earth orbit (LEO) satellites. These messages are generated by the operations control center based on monitoring data acquired by onboard and ground-based monitoring receivers. The complete navigation enhancement message includes all message information from the GNSS satellites to independently provide GNSS navigation enhancement and integrity enhancement services. The GNSS satellite message information includes ephemeris parameters, clock bias parameters, almanac parameters, ionospheric delay correction parameters, integrity information, and satellite constellation delay parameters. as well as Broadcasting the complete navigation enhancement message of the visible GNSS satellites, the low-orbit satellite navigation message, and the ranging signal of the low-orbit satellites to the user terminal includes: broadcasting the complete navigation enhancement message of each visible GNSS satellite in parallel in different orders according to the positions of the multiple visible GNSS satellites, using multiple low-orbit satellites adjacent to each other in the same orbit or multiple low-orbit satellites in the same phase in adjacent orbits.

2. The method of claim 1, wherein the step of generating and broadcasting the electronic text comprises the steps of: generating the electronic text; and broadcasting the electronic text. The complete navigation enhancement messages of each of the visible GNSS satellites are broadcast in parallel in reverse order, based on the positions of the multiple visible GNSS satellites, by multiple low-Earth orbit satellites that are adjacent to each other in the same orbit or multiple low-Earth orbit satellites that are in phase in adjacent orbits.

3. The method of claim 1, wherein the step of generating and broadcasting the electronic text comprises the steps of: generating the electronic text; and broadcasting the electronic text. The ephemeris parameters of the complete navigation enhancement message of the GNSS satellite are determined based on the Kepler 10-parameter ephemeris model, and the clock bias parameters are determined by the linear clock bias mode. The parameters of the Kepler 10 parameter ephemeris model include an ephemeris reference time an argument of perigee at the reference time an eccentricity a square root of semi-major axis at the reference time an inclination a rate of change of the inclination a longitude of ascending node at the reference time an argument of perigee sine harmonic coefficients of the amplitude of the latitude and cosine harmonic coefficients of the amplitude of the latitude .

4. The method of claim 1, wherein the step of generating and broadcasting the electronic text comprises the steps of: generating the electronic text; and broadcasting the electronic text. The almanac parameters are determined based on the grouping of satellites according to orbital altitude, orbital parity, and / or phase parity.

5. The method of claim 1, wherein the step of generating and broadcasting the electronic text comprises the step of: Also includes: ​ Receive regionalized parameters generated by the ground-based augmentation system of the target area; as well as The regionalization parameters of the target area are broadcast through the communication service channel.

6. The method of claim 5, wherein the step of generating and transmitting the electronic text comprises the step of: The regionalization parameter is the regionalized atmospheric delay parameter. ​ 7. A positioning method of a terminal device, characterized by, Including the following steps: The system receives complete navigation enhancement messages, low-orbit satellite navigation messages, and low-orbit satellite ranging signals broadcast by multiple low-orbit satellites. The complete navigation enhancement messages include all message information from the GNSS satellites to independently realize GNSS navigation enhancement services and GNSS integrity enhancement services. The message information from the GNSS satellites includes ephemeris parameters, clock bias parameters, almanac parameters, ionospheric delay correction parameters, integrity information, and satellite constellation delay parameters. as well as Based on the ranging signal of the GNSS satellite, the complete navigation enhancement message of the GNSS satellite, the navigation message of the LEO satellite, and the ranging signal of the LEO satellite, the PVT information of the terminal device is determined. The complete navigation enhancement message of the GNSS satellite is the complete navigation enhancement message of the visible GNSS satellite of the LEO satellite. The complete navigation enhancement message of the visible GNSS satellite is broadcast in parallel in different orders by multiple LEO satellites in the same orbit or multiple LEO satellites in the same phase in adjacent orbits, according to the positions of the multiple visible GNSS satellites.

8. The positioning method of a terminal device according to Claim 7, wherein The positioning method further includes: Receive regional parameters of the target area through the communication service channel; and By combining the regionalization parameters, the ranging signal of the GNSS satellite, the complete navigation enhancement message of the GNSS satellite, the navigation message of the low-Earth orbit satellite, and the ranging signal of the low-Earth orbit satellite, the PVT information of the terminal is determined.

9. A low-Earth orbit satellite, comprising: One or more processors; as well as One or more memories coupled to the one or more processors and storing instructions thereon, which, when executed individually or jointly by the one or more processors, cause the low-Earth orbit satellite to perform the message generation and broadcasting method for a low-Earth orbit satellite according to any one of claims 1-6.

10. A low orbit navigation augmentation system characterized by, This includes multiple low-orbit satellites as described in claim 9.

11. A terminal device, comprising: One or more processors; as well as One or more memories coupled to the one or more processors and storing instructions thereon, which, when executed individually or jointly by the one or more processors, cause the terminal device to perform the positioning method of the terminal device according to any one of claims 7-8.

12. A non-transitory computer-readable storage medium storing machine-executable instructions, which, when executed by one or more processors of a machine, cause the machine to perform the message generation and broadcasting method for a low-Earth orbit satellite according to any one of claims 1-6.

13. A non-transitory computer-readable storage medium storing machine-executable instructions, which, when executed by one or more processors of a machine, cause the machine to perform the positioning method of a terminal device according to any one of claims 7-8.

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