Navigation enhancement information broadcasting method, electronic device, storage medium, and program product

Abstract

Provided are a navigation enhancement information broadcasting method, an electronic device, a storage medium, and a program product, relating to the technical field of satellite navigation. The navigation enhancement information broadcasting method comprises: acquiring ephemeris data of GNSS satellites received by a low-orbit satellite; obtaining position information of the corresponding GNSS satellites at a target time according to the ephemeris data of the GNSS satellites; acquiring approximate position information of a terminal device at the target time; selecting, from the GNSS satellites to be selected, a GNSS satellite that is visible to both the low-orbit satellite and the terminal device at the target time as a target GNSS satellite according to the position information of the corresponding GNSS satellites at the target time, the approximate position information of the terminal device at the target time, and position information of the low-orbit satellite at the target time; and uploading navigation enhancement information of the target GNSS satellite to the low-orbit satellite, so as to broadcast the navigation enhancement information of the target GNSS satellite to the terminal device through the low-orbit satellite.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of satellite navigation technology, and in particular to a navigation enhancement information broadcasting method, an electronic device, a storage medium and a program product. BACKGROUND

[0002] Global Navigation Satellite System (GNSS) can realize continuous operation all day and all weather, and can realize seamless coverage in land, ocean, low altitude and near-earth space. It is one of the most widely used navigation technologies at present. With the deepening application of GNSS in land, railway, water conservancy, resources and military, etc., the demand for positioning time, positioning accuracy and integrity of GNSS is gradually increasing. Low-orbit satellites can improve the service quality and performance of GNSS satellites. However, the existing technology of using low-orbit satellites to provide GNSS satellite enhancement service has defects, which affects the positioning speed and accuracy of users. SUMMARY

[0003] In order to alleviate, mitigate or eliminate at least one of the above technical problems, the present disclosure provides a navigation enhancement information broadcasting method, an electronic device, a storage medium and a program product.

[0004] In a first aspect, the present disclosure provides a navigation enhancement information broadcasting method. The method comprises:

[0005] obtaining ephemeris data of GNSS satellites received by a low-orbit satellite;

[0006] obtaining position information of each GNSS satellite at a target time according to the ephemeris data of the GNSS satellite;

[0007] obtaining approximate position information of a terminal device at the target time;

[0008] selecting, according to the position information of the corresponding GNSS satellite at the target time, the approximate position information of the terminal device at the target time and the position information of the low-orbit satellite at the target time, a GNSS satellite visible to both the low-orbit satellite and the terminal device from candidate GNSS satellites as a target GNSS satellite, wherein the type of the candidate GNSS satellite is determined by the terminal device; and

[0009] annotating navigation enhancement information of the target GNSS satellite to the low-orbit satellite, so as to broadcast the navigation enhancement information of the target GNSS satellite to the terminal device through the low-orbit satellite.

[0010] In a second aspect, the disclosure provides an electronic device. The electronic 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 by the one or more processors alone or collectively, the electronic device performs the method of the first aspect.

[0011] In a third aspect, the disclosure provides a chip. The chip includes circuitry configured to perform the method of the first aspect.

[0012] In a fourth aspect, the disclosure provides a non-transitory computer-readable storage medium storing machine executable instructions. The machine executable instructions, when executed by one or more processors of a machine, cause the machine to perform the method of the first aspect.

[0013] In a fifth aspect, the disclosure provides a computer program product including machine executable instructions. The machine executable instructions, when executed by one or more processors of a machine, cause the machine to perform the method of the first aspect.

[0014] It should be understood that the summary is not intended to identify key or essential features of embodiments of the disclosure, nor is it intended to limit the scope of the disclosure. Other features, details, and advantages of the disclosure will become apparent from the following description of some embodiments of the disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0015] The above and other objects, features and advantages of the disclosure will become more apparent from the following description of some embodiments of the disclosure when taken in conjunction with the accompanying drawings, in which:

[0016] Figure 1 An exemplary communication network in which exemplary embodiments of the disclosure can be implemented is shown;

[0017] Figure 2 A flowchart of an exemplary method of navigation enhancement information broadcasting according to some embodiments of the disclosure is shown;

[0018] Figure 3 A flowchart of an exemplary method of selecting a target GNSS satellite according to some embodiments of the disclosure is shown;

[0019] Figure 4 A simplified block diagram of a device suitable for implementing exemplary embodiments of the disclosure is shown. DETAILED DESCRIPTION

[0020] The principles of the present disclosure will now be described with reference to some embodiments. It should be understood that the description of these embodiments is merely intended to illustrate the principles of the disclosure and to help the understanding and implementation of the disclosure by those skilled in the art, and does not suggest any limitation on the scope of the disclosure. The disclosure described herein can be implemented in ways different than those described below.

[0021] 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 belongs.

[0022] Reference herein to "one embodiment", "an embodiment", "exemplary embodiment", or the like, means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the disclosure. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an example embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other

[0023] It should be understood that although the terms "first" and "second" etc. can be used herein to describe various objects, these objects should not be limited by these terms. These terms are only used to distinguish one object from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of example embodiments. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed terms.

[0024] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising", when used in this specification, specify the presence of stated features, elements, and / or components, but do not preclude the presence or addition of one or more other features, elements, components, and / or groups thereof.

[0025] As used herein, the term "circuitry" can refer to one or more or all of the following:

[0026] (a) hardware-only circuitry implementations (e.g., implementations in analog circuitry and / or digital circuitry);

[0027] (b) combinations of hardware circuits and software, such as (as applicable):

[0028] (i) combinations of software and / or firmware and hardware circuitry;

[0029] (ii) any portions of hardware processor(s) with software (including digital signal processors) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions, and

[0030] (c) hardware circuitry and / or a processor, such as a microprocessor or a portion thereof, that requires software (e.g., firmware) for operation, but need not necessarily have such software (e.g., firmware) when it is not needed for operation.

[0031] This definition of circuitry applies to all uses of this term herein, including in any claims. As a further example, as used herein, the term circuitry also includes an implementation that is at least partially functional and / or that is combined with software and / or firmware on a hardware circuitry (or multiple hardware circuits), such as to create a general purpose hardware circuitry which is modeled upon more than one general purpose hardware circuitry.

[0032] As used herein, the term “communication network” refers to a network that follows any appropriate communication standard, such as Long Term Evolution (LTE), LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), High Speed Packet Access (HSPA), Narrow Band Internet of Things (NB-IoT), New Radio (NR), Non-Terrestrial Network (NTN), etc. In addition, communication between terminal devices and network devices in a communication network can be performed according to any appropriate generation communication protocol, including but not limited to, first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, fifth generation (5G), future sixth generation (6G) communication protocols, and / or any other protocols that are currently known or that will be developed in the future. Embodiments of the present disclosure can be applied in satellite communication systems. In view of the rapid development in communications, it will of course also be possible to use future types of communication technologies and systems in addition to those mentioned above. The scope of the present disclosure should therefore not be limited to the aforementioned systems.

[0033] The term “satellite network equipment” refers to a node provided on a satellite or a ground segment in a satellite communication network. Terminal equipment accesses the network and receives services therefrom through the node. Depending on the applied terminology and technology, the satellite network equipment can refer to a base station (BS) or an access point (AP) as a satellite payload, e.g. a Node B (NodeB or NB), an evolved Node B (eNodeB or eNB), an NR NB (also called gNB), a remote radio unit (RRU), a radio head (RH), a remote radio head (RRH), a relay node. An example of a relay node can be an integrated access and backhaul (IAB) node. The distributed unit (DU) part of an IAB node can perform the functions of “satellite network equipment” and thus can operate as network equipment. In the following description, the terms “satellite network equipment”, “BS” and “node” can be used interchangeably.

[0034] The term “terminal equipment” refers to any terminal equipment capable of wireless communication. By way of example and not limitation, a terminal equipment can also be referred to as a communication terminal, a communication device, a user equipment (UE), a subscriber station (SS), a portable user station, a mobile station (MS), or an access terminal (AT). The terminal equipment can include, but is not limited to, a mobile phone, a cellular phone, a smartphone, a voice over Internet Protocol (VoIP) phone, a wireless local loop phone, a tablet, a wearable terminal device, a personal digital assistant (PDA), a portable computer, a desktop computer, an image capture terminal equipment such as a digital camera, a game terminal device, a music storage and playback appliance, a vehicle-mounted wireless terminal equipment, a wireless endpoint, a mobile station, a laptop-embedded equipment (LEE), a laptop-mounted equipment (LME), a USB dongle, a smart device, a wireless customer-premises equipment (CPE), an Internet of Things (Iot) device, a watch or other wearable device, a head-mounted display (HMD), a vehicle, a drone, medical equipment and applications (e.g., remote surgery), industrial equipment and applications (e.g., robots in industrial and / or

[0035] Although the functionality described herein can be performed in various example embodiments in fixed and / or wireless network nodes, in other example embodiments, the functionality can be implemented in a user equipment device, such as a cellular phone, or a tablet computer, or a laptop computer, or a desktop computer, or a mobile Internet of Things device, or a fixed Internet of Things device. For example, the user equipment device can suitably have the respective capabilities described in relation to the fixed and / or wireless network nodes. The user equipment device can be a user equipment and / or a control device, e.g. a chipset or a processor, configured to control the user equipment when the user equipment is installed therein. Examples of these functionalities include a bootstrap server functionality and / or a home subscriber server, which can 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 functionalities / nodes.

[0036] Figure 1 An example communication network 100 in which embodiments of the present disclosure can be implemented is shown. The communication network 100 includes a satellite network device 110 and terminal devices 120A and 120B served by the satellite network device 110. The terminal devices 120A and 120B can also be collectively referred to as terminal devices 120. The communication network 100 can provide a serving cell 130 to serve the terminal devices 120A and 120B. In Figure 1 In an example, as a satellite communication network, the communication network 100 further includes a ground station 140, a gNB 150, a next generation core network NGC 160, and a data network 170. The satellite communication network can include low earth orbit (LEO), medium earth orbit (MEO), or geosynchronous earth orbit (GEO) satellites, and the satellite network device 110 can be carried on a low earth orbit (LEO), medium earth orbit (MEO), or geosynchronous earth orbit (GEO) satellite.

[0037] The ground station 140 acts as a gateway for connecting a non-terrestrial network and a public data network. The gNB 150 acts as an access network connecting the ground station 140 to the core network NGC 160. The NGC 160 can also be connected to the data network 170 to provide, for example, Internet content services. It will be understood that the communication network 100 need not include all of the elements shown in Figure 1 In an example, as a satellite communication network, the communication network 100 further includes a ground station 140, a gNB 150, a next generation core network NGC 160, and a data network 170. The satellite communication network can include low earth orbit (LEO), medium earth orbit (MEO), or geosynchronous earth orbit (GEO) satellites, and the satellite network device 110 can be carried on a low earth orbit (LEO), medium earth orbit (MEO), or geosynchronous earth orbit (GEO) satellite. Figure 1 In an example, as a satellite communication network, the communication network 100 further includes a ground station 140, a gNB 150, a next generation core network NGC 160, and a data network 170. The satellite communication network can include low earth orbit (LEO), medium earth orbit (MEO), or geosynchronous earth orbit (GEO) satellites, and the satellite network device 110 can be carried on a low earth orbit (LEO), medium earth orbit (MEO), or geosynchronous earth orbit (GEO) satellite.

[0038] In some embodiments, the satellite network devices 110 can be communicatively connected with the terminal devices 120A and 120B as base stations, and can also be transparent forwarding nodes that transparently forward signals transmitted by the ground station 140 to the terminal devices 120A and 120B. In the former case, the satellite network devices 110 have all or part of the functions of a base station. For example, the satellite network devices 110 can be gNBs or gNB-DUs, and the satellite network devices 110 having the functions of a gNB can have or not have inter-satellite links ISLs. In the case of transparent forwarding nodes, the satellite network devices 110 only perform transparent forwarding.

[0039] It should be understood that the number of satellite network devices 110, terminal devices 120A and 120B, and serving cells 130 is for illustrative purposes only and is not intended to be limiting. The communication network 100 can include any suitable number of satellite network devices, terminal devices, and serving cells suitable for implementing embodiments of the present disclosure. It should be noted that the terms “cell” and “serving cell” can be used interchangeably herein.

[0040] In the communication network 100, the satellite network devices 110 can transmit data and control information to the terminal devices 120A and 120B, and the terminal devices 120A and 120B can also transmit data and control information to the satellite network devices 110. The links from the satellite network devices 110 to the terminal devices 120A and 120B are called downlink (DL) or forward link, and the links from the terminal devices 120 to the satellite network devices 110 are called uplink (UL) or reverse link.

[0041] The communication in the communication network 100 can conform to any suitable standard, but is not limited to Long Term Evolution (LTE), LTE Evolution, LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), Code Division Multiple Access (CDMA), Global System for Mobile Communications (GSM), etc. Moreover, the communication can be performed according to any generation of communication protocol that is currently known or will be developed in the future. Examples of the communication protocol include, but are not limited to, first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, fifth generation (5G), sixth generation (6G) communication protocols.

[0042] There are four global navigation satellite systems (GNSS) in the world, including BeiDou navigation satellite system (BDS), global positioning system (GPS), Galileo navigation satellite system (Galileo), and global orbiting navigation satellite system (GLONASS). Low-orbit satellites can improve the service quality and performance of GNSS satellites. The way of providing GNSS satellite augmentation service by low-orbit satellites can be divided into two categories. One is to broadcast navigation augmentation information through low-orbit satellite communication link to assist in improving the positioning performance of GNSS. The other is to broadcast navigation ranging signals through low-orbit satellites, which can realize joint positioning with GNSS or independent navigation and positioning in GNSS failure environment.

[0043] For the first type of GNSS satellite augmentation service, the GNSS receiver carried by the low-orbit satellite observes the GNSS satellite signals that can be received, obtains GNSS satellite ephemeris, pseudorange observation value, carrier phase observation value and other information, improves the orbit and clock error accuracy of the GNSS satellite through high-low satellite joint orbiting technology, and then sends the navigation augmentation information (such as precise orbit, precise clock error, etc.) of the GNSS satellite to the terminal device through the communication payload carried by the low-orbit satellite. Because the communication rate of the low-orbit satellite is higher than the transmission rate of the GNSS satellite signal, the first positioning time of the terminal device can be greatly shortened. Because the low-orbit satellite obtains the GNSS satellite observation signal, it increases the redundant observation quantity participating in the solution of the orbit and clock error of the GNSS satellite, which can improve the solution accuracy of the orbit and clock error of the GNSS satellite. Based on the global observation quantity of the GNSS satellite obtained by the low-orbit satellite, the full-arc consistency of the orbit and clock error solution accuracy of the GNSS satellite can be improved, and the consistency of the terminal device positioning accuracy can be improved. It can be understood that the "GNSS satellite ephemeris" here refers to the navigation data broadcast by the GNSS satellite for describing its precise orbit and clock error parameters.

[0044] In an example embodiment, the low-orbit navigation enhancement system comprises a space segment and a ground segment. The space segment comprises at least one low-orbit satellite, and the space segment is composed of tens to hundreds of low-orbit satellites carrying navigation enhancement payloads, and the main task is to broadcast navigation enhancement information to various users. The ground segment comprises a ground operation and control system and a ground monitoring station, etc., which jointly complete the operation management and control of the on-orbit satellites. First, the low-orbit satellite receives GNSS satellite signals and obtains GNSS satellite ephemeris data, etc. The ground segment (such as the ground operation and control system) obtains GNSS satellite ephemeris data from the low-orbit satellite and calculates navigation enhancement information, uploads the navigation enhancement information to the low-orbit satellite, and then the low-orbit satellite broadcasts the navigation enhancement information to the terminal equipment of the user. The total number of satellites of the four GNSS systems of GPS, GLONASS, Galileo and BDS is about 120, and the number of satellites that can be observed by a single low-orbit satellite in real time is about 50. The low-orbit satellite mainly broadcasts navigation enhancement information in the coverage range of the beam centered on the subsatellite point. For convenience of description, it is assumed in the example embodiment of the disclosure that the number of GNSS satellites that can be observed by the low-orbit satellite is 50. If the navigation enhancement information of the 50 satellites is sent to the terminal equipment, since the subsatellite point of the low-orbit satellite and the position of the terminal equipment may not completely coincide, the low-orbit satellite may be near the terminal equipment at a low elevation angle, and therefore the 50 GNSS satellites visible to the low-orbit satellite are not completely visible to the terminal equipment, and the information of the invisible satellites is invalid information to the terminal equipment. At the same time, due to the limited communication channel resources of the low-orbit satellite, if the navigation enhancement information of the 50 GNSS satellites is sent to the terminal equipment, the time for the terminal equipment to receive the information is longer, and the first positioning time is also longer; in terms of resources, a single terminal equipment occupies more resources, and the total capacity of the terminal equipment served by a single low-orbit satellite also decreases.

[0045] The example embodiment of the disclosure proposes a navigation enhancement information broadcasting method, which is suitable for GNSS navigation enhancement based on low-orbit satellites. Through spatial geometric relationship, combined with the approximate position information of the terminal equipment and the position information of the low-orbit satellite, it is ensured that the GNSS navigation enhancement information sent by the low-orbit satellite to the terminal equipment corresponds to satellites visible to the terminal equipment (in an ideal observation environment). In addition, through the optimization strategy, the relatively optimal satellites are selected, the geometric configuration strength of the GNSS satellites is improved, the number of satellite GNSS navigation enhancement information to be broadcast is reduced, so as to shorten the information transmission time and improve the positioning accuracy of the terminal equipment.

[0046] Figure 2A flowchart of an exemplary method 200 of navigation augmentation information broadcasting according to some embodiments of the present disclosure is shown. The method 200 can be implemented on an electronic device or within a system. For example, the method 200 can be implemented in a ground segment of a low earth orbit navigation augmentation system. It should be understood that the method 200 can include additional steps not shown and / or some of the steps shown can be omitted, and the scope of the present disclosure is not limited in this regard.

[0047] At step S210, ephemeris data of GNSS satellites received by low earth orbit satellites is acquired.

[0048] The GNSS satellite ephemeris includes broadcast ephemeris. The broadcast ephemeris can be divided into BDS broadcast ephemeris, GLONASS broadcast ephemeris, Galileo broadcast ephemeris, GPS broadcast ephemeris and combined broadcast ephemeris according to satellite constellation. The acquired ephemeris data includes at least one of BDS broadcast ephemeris, GLONASS broadcast ephemeris, Galileo broadcast ephemeris and GPS broadcast ephemeris.

[0049] In some embodiments, the ephemeris of different satellite navigation systems is identified by the "RINEX VERSION / TYPE" field of the file header. For example, "G" identifies GPS satellites, "R" identifies GLONASS satellites, "E" identifies Galileo satellites and "C" identifies BDS satellites.

[0050] At step S220, the position information of the corresponding GNSS satellite at the target time is obtained according to the ephemeris data of each GNSS satellite.

[0051] After acquiring the ephemeris data of the GNSS satellites, relevant information can be extracted from the ephemeris, and then the position information of the GNSS satellites at the target time can be calculated according to the extracted information.

[0052] In an example embodiment, for a GPS satellite, satellite number, time, clock error, clock drift, clock drift rate, etc. data are extracted from the "SV / EPOCH / SV CLK" field, and 16 orbital parameter data of the satellite are extracted from the "BROADCAST ORBIT-1 to 4". For a Galileo satellite, satellite number, time, clock error, clock drift, clock drift rate, etc. data are extracted from the "SV / EPOCH / SV CLK" field, and 16 orbital parameter data of the satellite are extracted from the "BROADCAST ORBIT-1 to 4". For a GLONASS satellite, satellite number, time, clock error, clock drift, SV relative frequency deviation, message frame time, etc. data are extracted from the "SV / EPOCH / SV CLK" field, and satellite position, satellite speed, satellite acceleration, frequency number, health status, etc. data are extracted from the "BROADCAST ORBIT-1 to 3". For a BDS satellite, satellite number, time, clock error, clock drift, clock drift rate, etc. data are extracted from the "SV / EPOCH / SV CLK" field, and 16 orbital parameter data of the satellite are extracted from the "BROADCAST ORBIT-1 to 4". After the relevant information is extracted, the position of the GNSS satellite at the target time can be calculated. The method for calculating the position of the GNSS satellite is not limited in the present disclosure, and an example method is given below.

[0053] The average angular velocity of the GNSS satellite is calculated according to the earth gravity constant and the orbit semi-major axis. The mean anomaly of the GNSS satellite at the target time is calculated according to the average angular velocity, the angular velocity correction of the perigee, the ephemeris reference time, and the mean anomaly of the perigee at the ephemeris reference time. The perigee anomaly of the GNSS satellite at the target time is calculated according to the orbit eccentricity and the mean anomaly of the perigee at the target time. The true anomaly of the GNSS satellite at the target time is calculated according to the orbit eccentricity and the perigee anomaly at the target time. The node anomaly of the GNSS satellite at the target time is calculated according to the true anomaly of the GNSS satellite at the target time and the anomaly of the perigee. The perturbation correction term caused by the second-order zonal harmonic coefficient of the gravity field is calculated according to the node anomaly of the GNSS satellite at the target time, the sine correction of the node anomaly, the cosine correction of the node anomaly, the sine correction of the satellite radius, the cosine correction of the satellite radius, the sine correction of the orbit inclination, and the cosine correction of the orbit inclination. The corrected satellite radius of the GNSS satellite is calculated according to the orbit semi-major axis, the perigee anomaly at the target time, the orbit eccentricity, and the perturbation correction term of the satellite radius. The corrected true anomaly of the GNSS satellite is calculated according to the node anomaly and the perturbation correction term of the node anomaly. The corrected orbit inclination of the GNSS satellite is calculated according to the orbit inclination, the rate of change of the orbit inclination, and the perturbation correction term of the orbit inclination. The node longitude of the GNSS satellite is calculated according to the node equatorial radius of the GNSS satellite at the target time and the rate of change of the node equatorial radius. The position of the GNSS satellite in the orbit plane is calculated according to the corrected satellite radius and the true anomaly. The position of the GNSS satellite in the earth-centered coordinate system is calculated according to the node longitude, the corrected orbit inclination, and the position of the GNSS satellite in the orbit plane. The longitude and the latitude of the GNSS satellite on the earth at the target time are calculated according to the spherical geometry principle.

[0054] In step S230, the approximate position information of the terminal device at the target time is acquired.

[0055] The approximate position information of the terminal device at the target time is calculated by the terminal device. For example, the terminal device receives the signal broadcast by the GNSS satellite, calculates the approximate position information of the terminal device at the target time according to the received GNSS satellite signal, and then sends the approximate position information to the ground control system.

[0056] In step S240, the GNSS satellite visible to both the low-orbit satellite and the terminal device at the target time is selected as the target GNSS satellite from the candidate GNSS satellites according to the position information of the corresponding GNSS satellite at the target time, the approximate position information of the terminal device at the target time, and the position information of the low-orbit satellite at the target time.

[0057] The type of the candidate GNSS satellite is determined by the terminal device. The type of the candidate GNSS satellite includes at least one of a BDS satellite, a GLONASS satellite, a Galileo satellite, and a GPS satellite. The type of the candidate GNSS satellite can be obtained in advance by the ground control system from the terminal device, or can be sent in real time by the terminal device to the ground control system. Illustratively, a user can select a corresponding satellite navigation system according to his own needs, i.e., the user can set on the terminal device, or the terminal device automatically sets according to its own conditions. In some embodiments, the user sets to select GPS satellite navigation on the terminal device, and the corresponding candidate GNSS satellite is a GPS satellite; or the user sets to select BDS satellite navigation on the terminal device, and the corresponding candidate GNSS satellite is a BDS satellite; or the user sets to select GPS satellite navigation and BDS satellite navigation on the terminal device, and the corresponding candidate GNSS satellite includes a GPS satellite and a BDS satellite, or the user sets to select GNSS satellite navigation on the terminal device, and the corresponding candidate GNSS satellite is all GNSS satellites. It can be understood that the candidate GNSS satellite can be a GNSS satellite corresponding to the ephemeris data obtained in step S210, illustratively, the candidate GNSS satellite is a GPS satellite, and only the ephemeris data of the GPS satellite received by the low-orbit satellite is obtained in step S210, or the candidate GNSS satellite is included in the GNSS satellite corresponding to the ephemeris data obtained in step S210, illustratively, the candidate GNSS satellite is a GPS satellite, and the ephemeris data of all GNSS satellites received by the low-orbit satellite is obtained in step S210. In one exemplary embodiment, first, the ephemeris data of all GNSS satellites received by the low-orbit satellite is obtained in step S210, then the type of the candidate GNSS satellite is determined according to the satellite navigation system determined by the terminal device, and then the target GNSS satellite is selected from the candidate GNSS satellite.

[0058] In some embodiments, the target GNSS satellite includes K base stars, where K is an integer greater than or equal to 4. Step S240 includes the following sub-steps, as shown in Figure 3

[0059] In step S2411, a first elevation angle of the corresponding GNSS satellite relative to the low-orbit satellite is obtained according to the position information of the GNSS satellite at the target time and the position information of the low-orbit satellite at the target time.

[0060] Illustratively, the first elevation angle of the GNSS satellite relative to the low-orbit satellite at the target time is calculated according to the longitude and latitude of the GNSS satellite on the earth at the target time and the longitude and latitude of the low-orbit satellite on the earth at the target time.

[0061] ​At step S2412, the second elevation angle of each GNSS satellite relative to the terminal device is obtained according to the position information of the GNSS satellite at the target time and the approximate position information of the terminal device at the target time.

[0062] For example, the second elevation angle of the GNSS satellite relative to the terminal device at the target time is calculated according to the longitude and latitude of the GNSS satellite on the earth at the target time and the longitude and latitude of the terminal device on the earth at the target time.

[0063] At step S2413, the candidate GNSS satellites whose second elevation angles are greater than or equal to the first threshold value are selected as the base stars in order of the first elevation angles of the candidate GNSS satellites relative to the low-orbit satellite from large to small, until K base stars are selected.

[0064] In some embodiments, according to the type of the GNSS satellite, the GNSS satellites of the same type are sorted in order of the first elevation angles from large to small to obtain a first GNSS satellite sequence of the corresponding type; and according to the type of the candidate GNSS satellite, the candidate GNSS satellite is selected from the first GNSS satellite sequence of the corresponding type as a candidate base star, it is judged whether the second elevation angle of the candidate base star is greater than or equal to the first threshold value, and the candidate base star whose second elevation angle is greater than or equal to the first threshold value is selected as the base star, until K base stars are selected. In such embodiments, the satellite sequence of the corresponding type is obtained according to the type of the GNSS satellite, and the base star is selected from the satellite sequence of the corresponding type according to the satellite navigation system determined by the terminal device, which further improves the efficiency.

[0065] In an example embodiment, first elevation angles of all GNSS satellites relative to the low earth orbit satellite are sorted in descending order to form a satellite sequence {Sat1, Sat2,..., SatM}, where M is the number of satellites of all GNSS systems. First elevation angles of all BDS satellites relative to the low earth orbit satellite are sorted in descending order to form a satellite sequence {SatC1, SatC2,..., SatCM1}, where M1 is the number of satellites of all BDS systems. First elevation angles of all GPS satellites relative to the low earth orbit satellite are sorted in descending order to form a satellite sequence {SatG1, SatG2,..., SatGM2}, where M2 is the number of satellites of all GPS systems. First elevation angles of all GLONASS satellites relative to the low earth orbit satellite are sorted in descending order to form a satellite sequence {SatR1, SatR2,..., SatRM3}, where M3 is the number of satellites of all GLONASS systems. First elevation angles of all Galileo satellites relative to the low earth orbit satellite are sorted in descending order to form a satellite sequence {SatE1, SatE2,..., SatEM4}, where M4 is the number of satellites of all Galileo systems.

[0066] If the terminal device determines GNSS satellite navigation, the GNSS satellites to be selected include all satellites of the GNSS system, and the GNSS satellite navigation augmentation message needs to be broadcast, K satellites are selected from the satellite sequence {Sat1, Sat2,..., SatM} as base stars for terminal device positioning. For example, Sat1 is selected as the first candidate base star, and whether the terminal observation condition is satisfied is determined according to the second elevation angle of the GNSS satellite (Sat1) relative to the terminal device calculated in step S2412, i.e., whether the second elevation angle is greater than or equal to the first threshold. If the terminal observation condition is satisfied, Sat1 (i = 1) is selected as the first base star; if the terminal observation condition is not satisfied, Sat2 is selected as the second candidate base star, and whether the second elevation angle of Sat2 satisfies the terminal observation condition is determined, until a satellite Sat1 (i > 1) is selected as a base star. Sat1+1 is continuously selected as a candidate base star until K base stars are selected.

[0067] If the terminal device determines GNSS satellite navigation, the GNSS satellites to be selected include all satellites of the GNSS system, and the GNSS satellite navigation augmentation message needs to be broadcast, K satellites are selected from the satellite sequence {Sat1, Sat2,..., SatM} as base stars for terminal device positioning. For example, Sat1 is selected as the first candidate base star, and whether the terminal observation condition is satisfied is determined according to the second elevation angle of the GNSS satellite (Sat1) relative to the terminal device calculated in step S2412, i.e., whether the second elevation angle is greater than or equal to the first threshold. If the terminal observation condition is satisfied, Sat1 (i = 1) is selected as the first base star; if the terminal observation condition is not satisfied, Sat2 is selected as the second candidate base star, and whether the second elevation angle of Sat2 satisfies the terminal observation condition is determined, until a satellite Sat1 (i > 1) is selected as a base star. Sat1+1 is continuously selected as a candidate base star until K base stars are selected.

[0068] If the terminal device determines that the GPS satellite navigation, the GNSS satellite to be selected is a GPS satellite, and a GPS satellite navigation enhancement message needs to be broadcast. Referring to the above method, K satellites are selected from the satellite sequence {SatG1, SatG2,..., SatGM2} as the base stars.

[0069] If the terminal device determines that the GLONASS satellite navigation, the GNSS satellite to be selected is a GLONASS satellite, and a GLONASS satellite navigation enhancement message needs to be broadcast. Referring to the above method, K satellites are selected from the satellite sequence {SatR1, SatR2,..., SatRM3} as the base stars.

[0070] If the terminal device determines that the Galileo satellite navigation, the GNSS satellite to be selected is a Galileo satellite, and a Galileo satellite navigation enhancement message needs to be broadcast. Referring to the above method, K satellites are selected from the satellite sequence {SatE1, SatE2,..., SatEM4} as the base stars.

[0071] In some other embodiments, the GNSS satellites to be selected with the second elevation angle greater than or equal to the first threshold value are first screened, and then the base stars are selected in the order of the first elevation angle from large to small among the screened GNSS satellites to be selected. The K satellites with the largest first elevation angle among the screened GNSS satellites to be selected are the K base stars.

[0072] In some embodiments, in response to the number of the selected base stars being less than K, the method 200 is ended, and the GNSS satellite navigation enhancement information is not broadcast to the terminal device by the low-orbit satellite; and in response to the number of the selected base stars reaching K, the following steps are entered.

[0073] In some embodiments, the target GNSS satellite further includes N auxiliary stars, where N is an integer greater than or equal to 1. Then, step S240 further includes a step of selecting the auxiliary stars. Referring to Figure 3 , step S240 further includes the following sub-steps.

[0074] In step S2421, the first azimuth angle of the low-orbit satellite relative to the terminal device is obtained according to the approximate position information of the terminal device at the target time and the position information of the low-orbit satellite at the target time.

[0075] Exemplarily, the first azimuth angle of the low-orbit satellite relative to the terminal device at the target time is calculated according to the longitude and latitude of the terminal device on the earth at the target time and the longitude and latitude of the low-orbit satellite on the earth at the target time.

[0076] At step S2422, the second azimuth angle of the corresponding GNSS satellite relative to the terminal device is obtained according to the position information of the GNSS satellite at the target time and the approximate position information of the terminal device at the target time.

[0077] Exemplarily, the second azimuth angle of the GNSS satellite relative to the terminal device at the target time is calculated according to the longitude and latitude of the GNSS satellite on the earth at the target time and the longitude and latitude of the terminal device on the earth at the target time. It can be understood that step S2412 and step S2422 can be combined into one step, that is, the second elevation angle and the second azimuth angle of the GNSS satellite relative to the terminal device are calculated in one step.

[0078] At step S2423, according to the first azimuth angle and the second azimuth angle of the corresponding GNSS satellite relative to the terminal device, the candidate GNSS satellite that meets the azimuth angle uniform distribution standard and has a second elevation angle greater than or equal to the second threshold value is selected from the remaining candidate GNSS satellites except the K basic stars as an auxiliary star.

[0079] In some embodiments, the first azimuth angle is rotated by 180 degrees as a starting selected azimuth angle; the second azimuth angle of each GNSS satellite relative to the terminal device is subtracted from the starting selected azimuth angle and the absolute value is taken to obtain the azimuth angle difference of the corresponding GNSS satellite; and the candidate GNSS satellite that has a second elevation angle greater than or equal to the second threshold value and is not a basic star is selected in order of the azimuth angle difference of each candidate GNSS satellite from small to large as an auxiliary star until the first auxiliary star is selected.

[0080] In one exemplary embodiment, according to the type of the GNSS satellite, the GNSS satellites belonging to the same type are sorted in order of the azimuth angle difference from small to large to obtain a second GNSS satellite sequence of the corresponding type; and according to the type of the candidate GNSS satellite, the candidate GNSS satellite is selected from the second GNSS satellite sequence of the corresponding type in order as a candidate auxiliary star, it is judged whether the second elevation angle of the candidate auxiliary star is greater than or equal to the second threshold value and whether the candidate auxiliary star is a basic star, and the candidate auxiliary star that is not a basic star and has a second elevation angle greater than or equal to the second threshold value is selected as an auxiliary star until the first auxiliary star is selected.

[0081] Exemplarily, the azimuth differences of all GNSS satellites are sorted in ascending order to form a satellite sequence {Sat'1, Sat'2,..., Sat'M}. The azimuth differences of all BDS satellites are sorted in ascending order to form a satellite sequence {SatC'1, SatC'2,..., SatC'M1}. The azimuth differences of all GPS satellites are sorted in ascending order to form a satellite sequence {SatG'1, SatG'2,..., SatG'M2}. The azimuth differences of all GLONASS satellites are sorted in ascending order to form a satellite sequence {SatR'1, SatR'2,..., SatR'M3}. The azimuth differences of all Galileo satellites are sorted in ascending order to form a satellite sequence {SatE'1, SatE'2,..., SatE'M4}.

[0082] If the terminal device determines GNSS satellite navigation, the to-be-selected GNSS satellite includes all satellites of the GNSS system, and the GNSS satellite navigation augmentation message needs to be broadcast, a first satellite Sat'1 in the satellite sequence {Sat'1, Sat'2,..., Sat'M} is selected as a to-be-selected auxiliary satellite, and it is determined whether the satellite meets the auxiliary satellite selection criterion, that is, whether the second elevation angle is greater than or equal to the second threshold value and whether the satellite is a basic satellite. If the auxiliary satellite selection criterion is met, Sat'1 is selected as the first auxiliary satellite; if the auxiliary satellite selection criterion is not met, Sat'2 is selected as a to-be-selected auxiliary satellite, and the process is repeated until the first auxiliary satellite is selected.

[0083] If the terminal device determines BDS satellite navigation, the to-be-selected GNSS satellite is a BDS satellite, and the BDS satellite navigation augmentation message needs to be broadcast, the first auxiliary satellite is selected from the satellite sequence {SatC'1, SatC'2,..., SatC'M1} according to the above method.

[0084] If the terminal device determines GPS satellite navigation, the to-be-selected GNSS satellite is a GPS satellite, and the GPS satellite navigation augmentation message needs to be broadcast, the first auxiliary satellite is selected from the satellite sequence {SatG'1, SatG'2,..., SatG'M2} according to the above method.

[0085] If the terminal device determines GLONASS satellite navigation, the to-be-selected GNSS satellite is a GLONASS satellite, and the GLONASS satellite navigation augmentation message needs to be broadcast, the first auxiliary satellite is selected from the satellite sequence {SatR'1, SatR'2,..., SatR'M3} according to the above method.

[0086] If the terminal device determines that the Galileo satellite navigation, the to-be-selected GNSS satellite is a Galileo satellite, and the Galileo satellite navigation augmentation message needs to be broadcast, the first auxiliary satellite is selected from the satellite sequence {SatE'1, SatE'2,..., SatE'M4} according to the above method.

[0087] In another exemplary embodiment, the to-be-selected GNSS satellites with the second elevation angle greater than or equal to the second threshold value are first screened, and then the auxiliary satellites are selected in the screened to-be-selected GNSS satellites in the order of the azimuth angle difference from small to large, and the satellite with the smallest azimuth angle difference and not being the base satellite in the screened to-be-selected GNSS satellites is taken as the first auxiliary satellite. It can be understood that the second threshold value and the first threshold value can be equal or not equal. In the case that the second threshold value and the first threshold value are equal, the to-be-selected GNSS satellites with the second elevation angle greater than or equal to the first threshold value are first screened, and then the K base satellites are selected from the screened to-be-selected GNSS satellites, and then the auxiliary satellites are selected from the remaining to-be-selected GNSS satellites.

[0088] For N greater than or equal to 2, more auxiliary satellites need to be selected. The starting selection azimuth angle for selecting the i-1 auxiliary satellite is rotated by (360 / N) degrees to be taken as the starting selection azimuth angle for selecting the i auxiliary satellite, where i is greater than or equal to 2 and less than or equal to N; the second azimuth angle of each GNSS satellite relative to the terminal device is subtracted from the starting selection azimuth angle for selecting the i auxiliary satellite to obtain the new azimuth angle difference of the corresponding GNSS satellite; and the to-be-selected GNSS satellites with the second elevation angle greater than or equal to the second threshold value and not being the base satellite are selected in the order of the new azimuth angle difference of each to-be-selected GNSS satellite from small to large as the auxiliary satellites until the i auxiliary satellite is selected.

[0089] In some embodiments, according to the type of the GNSS satellite, the GNSS satellites belonging to the same type are sorted in the order of the new azimuth angle difference from small to large to obtain a new second GNSS satellite sequence of the corresponding type; and according to the type of the to-be-selected GNSS satellite, the to-be-selected GNSS satellite is selected from the new second GNSS satellite sequence of the corresponding type as the to-be-selected auxiliary satellite, it is judged whether the second elevation angle of the to-be-selected auxiliary satellite is greater than or equal to the second threshold value and whether the to-be-selected auxiliary satellite is the base satellite, and the to-be-selected auxiliary satellite corresponding to the second elevation angle greater than or equal to the second threshold value and not being the base satellite is taken as the auxiliary satellite until the i auxiliary satellite is selected. The specific screening method can refer to the screening method of the first auxiliary satellite described above, which will not be described in detail here.

[0090] In some embodiments, in response to the number of selected auxiliary stars being less than N, ending the method 200 without broadcasting, by the low earth orbit satellite, navigation augmentation information of the GNSS satellites to the terminal device; and in response to the number of selected auxiliary stars reaching N, then entering the following steps.

[0091] In step S250, the navigation augmentation information of the target GNSS satellite is uploaded to the low earth orbit satellite for broadcasting, by the low earth orbit satellite, the navigation augmentation information of the target GNSS satellite to the terminal device.

[0092] In some embodiments, if the terminal device determines GNSS satellite navigation, a GNSS satellite navigation augmentation message is broadcast, and navigation augmentation information messages of the corresponding K base stars and N auxiliary stars are arranged and sent to the terminal device by the low earth orbit satellite. If the terminal device determines BDS satellite navigation, a BDS satellite navigation augmentation message is broadcast, and navigation augmentation information messages of the corresponding K base stars and N auxiliary stars are arranged and sent to the terminal device by the low earth orbit satellite. If the terminal device determines GPS satellite navigation, a GPS satellite navigation augmentation message is broadcast, and navigation augmentation information messages of the corresponding K base stars and N auxiliary stars are arranged and sent to the terminal device by the low earth orbit satellite. If the terminal device determines GLONASS satellite navigation, a GLONASS satellite navigation augmentation message is broadcast, and navigation augmentation information messages of the corresponding K base stars and N auxiliary stars are arranged and sent to the terminal device by the low earth orbit satellite. If the terminal device determines Galileo satellite navigation, a Galileo satellite navigation augmentation message is broadcast, and navigation augmentation information messages of the corresponding K base stars and N auxiliary stars are arranged and sent to the terminal device by the low earth orbit satellite.

[0093] The embodiments of the present disclosure comprehensively consider the relative relationship between the GNSS satellites, the low earth orbit satellites and the terminal device, ensure that the navigation augmentation information broadcast contains GNSS satellites that are visible to both the low earth orbit satellites and the terminal device, and shield invalid information to the terminal device. In addition, the embodiments of the present disclosure also comprehensively consider the elevation angle of the GNSS satellites, the spatial configuration of the GNSS satellites and the low earth orbit satellites relative to the terminal device, optimize the geometric configuration of the target GNSS satellite relative to the terminal device, and improve the convergence speed and accuracy of the terminal device position solution.

[0094] Embodiments of the present disclosure also provide a low earth orbit navigation augmentation system. The low earth orbit navigation augmentation system includes a space segment and a ground segment, the space segment includes at least one low earth orbit satellite, and the ground segment is configured to perform the steps of any process of the disclosed. Figures 2-3 any process of the disclosed.

[0095] Embodiments of the present disclosure also provide a chip. The chip includes circuitry configured to perform the steps of any process of the disclosed. Figures 2-3Any of the processes discussed in the disclosure.

[0096] Figure 4 is a simplified block diagram of a device 400 suitable for implementing embodiments of the disclosure. For example, the satellite network device 110, the terminal device 120, the electronic device can be implemented by the device 400. As shown, the device 400 includes one or more processors 410, one or more memories 420 coupled to the processors 410, and one or more communication modules 440 coupled to the processors 410. Figure 4

[0097] The communication module 440 is for bidirectional communication. The communication module 440 has at least one antenna to facilitate communication. The communication interface can represent any interface necessary to communicate with other network elements.

[0098] The processor 410 can be of any type suitable to the local technical network and can include, by way of non-limiting example, one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multi-core processor architectures, as non-limiting examples. The device 400 can have multiple processors for

[0099] The memory 420 can include one or more non-transitory memories and one or more transitory memories. Examples of non-transitory memories include, but are not limited to, read-only memory (ROM) 424, electrically programmable read only memory (EPROM), flash memory, hard disks, compact disks (CDs), digital video disks (DVDs), and other magnetic and / or optical storage devices. Examples of transitory memories include, but are not limited to, random access memories (RAM) 422 and other volatile memories that do not persist for the duration of power loss.

[0100] The computer program 430 includes computer executable instructions executed by the relevant processor 410. The computer program 430 can be stored in the ROM 424. The processor 410 can perform any appropriate action and process by loading the computer program 430 into the RAM 422.

[0101] Embodiments of the disclosure can be implemented by the program 430, so that the device 400 can perform any of the processes discussed in the disclosure. Embodiments of the disclosure can also be implemented by hardware or by a combination of software and hardware. Figures 2-3

[0102] ​​In some embodiments, the computer program 430 can be tangibly embodied in a computer-readable medium, which can be included in the device 400 (e.g., the memory 420) or in another storage device accessible by the device 400. The device 400 can load the computer program 430 from the computer-readable medium into the RAM 422 for execution by the processor or controller. The computer-readable medium can include any type of tangible non-transitory memory, such as ROM, EPROM, flash memory, a hard disk, a CD-ROM, a DVD, and the like. The computer program 430 is stored on the computer-readable medium.

[0103] In general, the various embodiments of the disclosure can be implemented in hardware or special-purpose circuits, software, logic, or any combination thereof. Some aspects can be implemented in hardware, while other aspects can be implemented in firmware or software which can be executed by a controller, microprocessor or other computing device. While various aspects of an embodiment of the disclosure are illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein can be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

[0104] Embodiments of the disclosure also provide at least one computer program product which is tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, executed by devices in a target real or virtual processor to perform any of the processes of the disclosure described above. Figures 2-3 Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform particular tasks or implement particular abstract data types. The functionality of the program modules can be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules can be executed within the local or distributed device. In a distributed device, program modules can be located in local and remote memory storage devices.

[0105] Program code for carrying out methods of embodiments of the disclosure can be written in any combination of one or more programming languages. The program code can be executed by a processor or controller of a general purpose computer, a special purpose computer, or other programmable data processing apparatus to produce the functions / operations specified in the flowcharts and / or block diagrams. The program code can be supplied to a computer, or other programmable data processing apparatus, to produce a machine, such that the computer or other programmable data processing apparatus implement the functions / operations specified in the flowcharts and / or block diagrams. The program code can be supplied to the computer or other programmable data processing apparatus as a sequence of one or more computer-readable storage media, partially or entirely within the computer or other programmable data processing apparatus.

[0106] In the context of this document, a computer program code or related data can be carried by any suitable carrier and means that enable a device, apparatus, or processor to execute the various processing and operations described above. Examples of carriers include signals, computer readable media, etc.

[0107] The computer readable medium can be a computer readable signal medium or a computer readable storage medium. The computer readable medium can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the computer readable storage medium include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0108] Further, while operations are depicted in a particular order, this should not be understood as requiring the operations to be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing can be advantageous. Likewise, while several specific implementation details are contained in the above discussion, these should not be construed as limiting the scope of the disclosure, but merely as describing specific features. Certain features that are described in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable sub-combination.

[0109] While the disclosure has been described in terms of specific embodiments thereof, it is to be understood that the disclosure defined in the appended claims is not necessarily limited to the specific features or acts described, or to the combination of features thereof. Rather, the specific features and acts described above are disclosed as illustrative forms of implementing the claims.

[0110] It should be well understood by those of ordinary skill in the art that the use of personal identifiable information should follow privacy policies and practices that are generally considered to meet or exceed industry or governmental requirements for maintaining the privacy of users. In particular, personally identifiable information data should be managed and processed so as to minimize the risk of inadvertent or unauthorized access or use, and the nature of authorized use should be clearly indicated to users.

Claims

1. A method of broadcasting navigation enhancement information, characterized by, The method comprises: acquiring ephemeris data of GNSS satellites received by a low-orbit satellite; obtaining position information of each GNSS satellite at a target time according to the ephemeris data of the GNSS satellite; acquiring approximate position information of a terminal device at the target time; selecting, according to the position information of each GNSS satellite at the target time, the approximate position information of the terminal device at the target time, and the position information of the low-orbit satellite at the target time, a GNSS satellite visible to both the low-orbit satellite and the terminal device from candidate GNSS satellites as a target GNSS satellite, wherein the type of the candidate GNSS satellite is determined by the terminal device; and annotating navigation enhancement information of the target GNSS satellite to the low-orbit satellite, so as to broadcast the navigation enhancement information of the target GNSS satellite to the terminal device through the low-orbit satellite; wherein the target GNSS satellite comprises K base stars, wherein K is an integer greater than or equal to 4, and the selecting, according to the position information of each GNSS satellite at the target time, the approximate position information of the terminal device at the target time, and the position information of the low-orbit satellite at the target time, a GNSS satellite visible to both the low-orbit satellite and the terminal device from candidate GNSS satellites as a target GNSS satellite comprises: obtaining a first elevation angle of each GNSS satellite relative to the low-orbit satellite according to the position information of the GNSS satellite at the target time and the position information of the low-orbit satellite at the target time; obtaining a second elevation angle of each GNSS satellite relative to the terminal device according to the position information of the GNSS satellite at the target time and the approximate position information of the terminal device at the target time; and selecting, in descending order of the first elevation angle of each candidate GNSS satellite relative to the low-orbit satellite, a candidate GNSS satellite with a second elevation angle greater than or equal to a first threshold value as the base star, until K base stars are selected.

2. The method of claim 1, wherein, The selecting, in descending order of the first elevation angle of each candidate GNSS satellite relative to the low-orbit satellite, a candidate GNSS satellite with a second elevation angle greater than or equal to a first threshold value as the base star, until K base stars are selected, comprises: sorting GNSS satellites of the same type in descending order of the first elevation angle to obtain a first GNSS satellite sequence of the corresponding type according to the type of the GNSS satellite; and selecting, according to the type of the candidate GNSS satellite, a candidate base star from the first GNSS satellite sequence of the corresponding type, judging whether the second elevation angle of the candidate base star is greater than or equal to the first threshold value, and selecting, as the base star, a candidate base star with a second elevation angle greater than or equal to the first threshold value, until K base stars are selected.

3. The method of claim 1, wherein, The target GNSS satellite further comprises N auxiliary stars, where N is an integer greater than or equal to 1, and the selecting the GNSS satellite visible to both the low-orbit satellite and the terminal device from the candidate GNSS satellites as the target GNSS satellite according to the position information of the corresponding GNSS satellite at the target time, the approximate position information of the terminal device at the target time, and the position information of the low-orbit satellite at the target time further comprises: obtaining a first azimuth angle of the low-orbit satellite relative to the terminal device according to the approximate position information of the terminal device at the target time and the position information of the low-orbit satellite at the target time; obtaining a second azimuth angle of each GNSS satellite relative to the terminal device according to the position information of each GNSS satellite at the target time and the approximate position information of the terminal device at the target time; and selecting the candidate GNSS satellite that meets the azimuth angle uniform distribution standard and has a second elevation angle greater than or equal to a second threshold from the remaining candidate GNSS satellites other than the K base stars as the auxiliary star according to the first azimuth angle and the second azimuth angle of the corresponding GNSS satellite relative to the terminal device.

4. The method of claim 3, wherein, The selecting the candidate GNSS satellite that meets the azimuth angle uniform distribution standard and has a second elevation angle greater than or equal to a second threshold from the remaining candidate GNSS satellites other than the K base stars as the auxiliary star according to the first azimuth angle and the second azimuth angle of the corresponding GNSS satellite relative to the terminal device further comprises: rotating the first azimuth angle by 180 degrees as a starting selection azimuth angle; obtaining an azimuth angle difference of each GNSS satellite by subtracting the starting selection azimuth angle from the second azimuth angle of each GNSS satellite relative to the terminal device and taking the absolute value; and selecting the candidate GNSS satellite that has a second elevation angle greater than or equal to a second threshold and is not the base star as the auxiliary star in the order of the azimuth angle difference of each candidate GNSS satellite from small to large, until the first auxiliary star is selected.

5. The method of claim 4, wherein, N is greater than or equal to 2, and the selecting the candidate GNSS satellite that meets the azimuth angle uniform distribution standard and has a second elevation angle greater than or equal to a second threshold from the remaining candidate GNSS satellites other than the K base stars as the auxiliary star according to the first azimuth angle and the second azimuth angle of the corresponding GNSS satellite relative to the terminal device further comprises: rotating the starting selection azimuth angle used to select the i-1th auxiliary star by (360 / N) degrees as the starting selection azimuth angle used to select the i th auxiliary star, where i is greater than or equal to 2 and less than or equal to N; obtaining a new azimuth angle difference of each GNSS satellite by subtracting the starting selection azimuth angle used to select the i th auxiliary star from the second azimuth angle of each GNSS satellite relative to the terminal device and taking the absolute value; and selecting the candidate GNSS satellite that has a second elevation angle greater than or equal to a second threshold and is not the base star as the auxiliary star in the order of the new azimuth angle difference of each candidate GNSS satellite from small to large, until the i th auxiliary star is selected.

6. The method of claim 4, wherein, the auxiliary satellites are selected in order from the candidate GNSS satellites whose azimuth differences are in ascending order, until the first auxiliary satellite is selected, including: the GNSS satellites of the same type are sorted in ascending order of the new azimuth differences, to obtain a new second GNSS satellite sequence of the corresponding type; and the auxiliary satellites are selected in order from the candidate GNSS satellites whose new azimuth differences are in ascending order, until the ith auxiliary satellite is selected, including:

7. The method of claim 5, wherein, the GNSS satellites of the same type are sorted in ascending order of the new azimuth differences, to obtain a new second GNSS satellite sequence of the corresponding type; and the auxiliary satellites are selected in order from the candidate GNSS satellites whose new azimuth differences are in ascending order, until the ith auxiliary satellite is selected, including: the GNSS satellites of the same type are sorted in ascending order of the new azimuth differences, to obtain a new second GNSS satellite sequence of the corresponding type; and 8. The method of any one of claims 1-7, wherein, the auxiliary satellites are selected in order from the candidate GNSS satellites whose new azimuth differences are in ascending order, until the ith auxiliary satellite is selected, including: the ephemeris data obtained includes at least one of BDS broadcast ephemeris, GLONASS broadcast ephemeris, Galileo broadcast ephemeris and GPS broadcast ephemeris; 9. The method of any one of claims 3-7, wherein, the types of the candidate GNSS satellites include at least one of BDS satellites, GLONASS satellites, Galileo satellites and GPS satellites. Further comprising: in response to the number of the selected base stars being less than K, ending the method; in response to the number of the selected base stars reaching K, entering the step of selecting the auxiliary satellites; in response to the number of the selected auxiliary satellites being less than N, ending the method; and in response to the number of the selected auxiliary satellites reaching N, uploading the navigation enhancement information of the target GNSS satellite to the low-orbit satellite.

10. An electronic device, comprising: comprising: one or more processors; and one or more memories coupled to the one or more processors and storing instructions thereon that, when executed by the one or more processors individually or collectively, cause the electronic device to perform the method of any one of claims 1-9. comprising circuitry configured to perform the method of any one of claims 1-9.

11. A chip, characterized by comprising circuitry configured to perform the method of any one of claims 1-9.

12. A non-transitory computer-readable storage medium having stored thereon machine executable instructions, the machine executable instructions, when executed by one or more processors of a machine, cause the machine to perform the method of any one of claims 1-9.

13. A computer program product comprising machine executable instructions, the machine executable instructions, when executed by one or more processors of a machine, cause the machine to perform the method of any one of claims 1-9.

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