Satellite switching method and system for NTN high-orbit and low-orbit integrated network

Abstract

The present invention discloses a satellite switching method and system for a NTN (National Telecommunication Network) high-Earth Orbit (NTN) fusion network. The method comprises: step S1: the UE obtains its own position via GNSS and reports it to the source satellite, obtaining a list of candidate satellites permitted to access and measurement configuration from the source satellite; step S2: the UE begins measurement after receiving the candidate satellite list and updates the candidate satellite list based on the measurement results; step S3: the UE measures all satellites in the updated candidate satellite list; low-Earth orbit satellites and geostationary orbit satellites that meet the conditions are sorted based on the measurement results and candidate satellite information, and satellite switching is performed based on the sorting results. The present invention improves the success rate and communication continuity of UE conditional switching, dynamically reduces switching decision delay and signaling interaction load, and fully leverages the synergistic advantages of low latency of LEO and wide coverage of GEO.

Description

Technical Field

[0001] The present invention relates to the field of satellite communications, and in particular to a satellite switching method and system for an NTN high-orbit and low-orbit fusion network. Background Art

[0002] A non-terrestrial network (NTN) uses satellites and other non-terrestrial communication infrastructure to achieve global coverage. It offers advantages such as wide coverage and long communication distances. NTN cells can have a coverage radius of tens to hundreds of kilometers and typically utilize the following two solutions.

[0003] 1) Earth-fixed cell solution: This refers to an NTN solution that fixes a satellite cell at a specific location on Earth for a specific period of time. The continuous service duration of this solution depends on the satellite's orbital altitude and minimum elevation angle, and can range from several minutes to tens of minutes.

[0004] 2) Earth Moving Cell Solution: This refers to an NTN solution in which satellite cells continuously move across the Earth's surface. The satellite cell beam footprint sweeps across the ground, and the cell's coverage location shifts with the satellite's movement. The continuous service duration of this solution depends on the satellite's orbital altitude and beam coverage diameter, and can range from a few seconds to tens of seconds.

[0005] The 3rd Generation Partnership Project (3GPP) Rel-17 defines the basic mobility management process for NTNs in a connected state. The network issues measurement and reporting configurations to the UE (User Equipment). After completing measurements, the UE reports the measurement report, and the network uses the measurement report to determine whether to initiate a handover. Reporting can be triggered periodically or based on events. Furthermore, because NTN cells are covered by satellites, the signal strength at the cell center and at the cell edge differs only slightly, meaning that there is no significant near-far effect for NTN cells. Therefore, in 3GPP 5G NTN, for connected terminals, inter-cell handover can primarily be accomplished through conditional handover.

[0006] The basic principle of conditional handover (CHO) is that the network pre-configures neighboring cell information and handover thresholds. If the handover conditions are met, the UE can perform handover without having to report measurements or receive handover instructions from the network. This reduces handover failures caused by handover command failures, increases handover success rates, and reduces handover signaling. Rel-17 NTN adds two new CHO trigger conditions: time-based and location-based. However, these time-based or location-based triggers must be configured alongside the signal quality measurement-based triggers already in use by the terrestrial network. The time-based trigger (also known as the T1 event) is defined as a CHO that can only be executed during a period of time related to the time when the satellite corresponding to the candidate target cell passes over the terminal. The location-based CHO trigger (also known as the D1 event) is defined as the time when the distance between the terminal and the terrestrial fixed reference point of the serving cell becomes greater than a threshold, and the distance between the terminal and the terrestrial fixed reference point of the candidate target cell becomes less than a threshold.

[0007] In a converged high-orbit network, LEO (Low Earth Orbit) and GEO (Geostationary Earth Orbit) satellites together form the NTN. Since GEO satellites orbit at an altitude of approximately 35,786 kilometers, this results in significant propagation delay and path loss in the satellite-to-ground link. Furthermore, while GEO satellites offer wide coverage and can simultaneously serve a large number of users, system load distribution is difficult to dynamically adjust based on user distribution, especially in a multi-user environment where available resources are increasingly scarce. LEO satellites, due to their relative proximity to the ground, offer low propagation delay, but their rapid movement may necessitate frequent handoffs between user terminals and satellites during communication.

[0008] Different UEs utilize different services. Based on the description of service delay tolerance in ITU-T G.1010 (International Telecommunication Union. Recommendation ITU-R G.1010: End-user multimedia QoS categories[R]. Geneva: ITU, 2001.), services are divided into four levels. Different service levels are handled differently based on their maximum delay tolerance. Services with different delay tolerances have different requirements for target satellites, as shown in Table 1.

[0009] In the CHO process defined in existing protocols, a source satellite (i.e., a source base station and satellite, with the base station deployed on the satellite) sends CHO requests to multiple candidate satellites (base stations and satellites). The candidate satellites (base stations and satellites) then send CHO responses to the source satellite. After receiving the responses from the candidate satellites, the source satellite delivers a candidate cell list to the UE. Thereafter, the source satellite no longer monitors the status of the candidate satellites, no longer updates the list for the UE, and does not control the UE's handover direction.

[0010] For a period of time after the source satellite sends the candidate satellite list to the UE, the UE cannot know the channel status of the candidate satellites at the current moment, whether the ephemeris information has changed, and how the changes have occurred. At the same time, the source satellite will not control the UE to select the target satellite, increasing the risk of UE handover failure. For example, the candidate satellite has reached its maximum throughput and cannot access new UEs, but it is still selected as the target satellite by the UE and attempts to switch access.

[0011] At the same time, there is currently a lack of standardized methods for UEs to select target satellites in high-orbit and low-orbit integrated networks. In order for a UE to select an appropriate target satellite, it is necessary to consider multiple factors that affect the quality of service (QoS) in the UE's connected state, including: the 3GPP-specified measurement RSRQ (Reference Signal Receiving Quality), the distance between the UE and the satellite beam center, the duration of satellite service, the communication delay that affects QoS, and the satellite load, so as to select the most suitable target satellite for switching. Summary of the Invention

[0012] The technical problem to be solved by the embodiments of the present invention is to provide a satellite switching method and system for the NTN high-orbit and low-orbit integrated network, so as to solve the problems of delayed update of candidate satellite information, lack of multi-factor comprehensive decision-making, and insufficient adaptation of high-orbit and low-orbit satellite characteristics.

[0013] In order to solve the above technical problems, an embodiment of the present invention proposes a satellite switching method for an NTN high-orbit and low-orbit integrated network, comprising:

[0014] Step S1: After establishing a connection with the source satellite, the UE obtains its own position through GNSS and reports it to the source satellite, and obtains a list of candidate satellites allowed to access and measurement configuration from the source satellite;

[0015] Step S2: After receiving the candidate satellite list, the UE starts measurement and updates the candidate satellite list according to the measurement results;

[0016] Step S3: The UE measures all satellites in the updated candidate satellite list; sorts the low earth orbit satellites and geostationary orbit satellites that meet the conditions according to the measurement results and the candidate satellite information, and switches the satellites according to the sorting results.

[0017] Accordingly, an embodiment of the present invention further provides a satellite switching system for an NTN high-orbit and low-orbit integrated network, comprising:

[0018] Reporting module: After establishing a connection with the source satellite, the UE obtains its own position through GNSS and reports it to the source satellite, and obtains the list of candidate satellites allowed to access and measurement configuration from the source satellite;

[0019] Measurement update module: After receiving the candidate satellite list, the UE starts measurement and updates the candidate satellite list based on the measurement results;

[0020] Sorting and switching module: The UE measures all satellites in the updated candidate satellite list; sorts the low-Earth orbit satellites and geostationary orbit satellites that meet the conditions based on the measurement results and candidate satellite information, and switches satellites based on the sorting results.

[0021] The beneficial effects of the present invention are:

[0022] 1) Improving handover success rates and QoS (Quality of Service) guarantees: This invention dynamically updates the candidate satellite list to prevent UEs from attempting to access unavailable or overloaded satellites, reducing the probability of handover failures. It also uses an entropy-based multi-factor optimization ranking method to ensure that the load, latency, and signal quality of the selected satellites meet service requirements, thereby improving communication continuity.

[0023] 2) Enhanced adaptability of high and low orbit networks: This invention addresses the short-term services of LEO satellites and the high latency characteristics of GEO satellites. Through a service level differentiation strategy, latency-sensitive services prioritize LEO satellites, while non-sensitive services flexibly utilize the wide coverage of GEO, thereby optimizing resource utilization.

[0024] 3) Reduce signaling overhead and decision delay: The objective weight calculation based on the entropy weight method in this invention reduces the complexity of manual configuration. The dynamic sorting mechanism reduces UE repeated measurements and satellite signaling interactions, shortens handover decision time, and is suitable for highly dynamic scenarios in satellite networks. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present invention is a flowchart of a satellite switching method for an NTN high-orbit and low-orbit integrated network according to an embodiment of the present invention.

[0026] Figure 2 It is a schematic diagram of the UE measurement process according to an embodiment of the present invention.

[0027] Figure 3 This is a CHO switching flow chart for switching to a LEO satellite according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] It should be noted that, unless there is a conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The present invention is further described in detail below with reference to the drawings and specific embodiments.

[0029] In the embodiments of the present invention, if there are directional indications (such as up, down, left, right, front, back, etc.), they are only used to explain the relative position relationship and movement status of the various components under a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0030] In addition, the terms "first," "second," and so on, used in this disclosure are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features being referred to. Therefore, features specified as "first" or "second" may explicitly or implicitly include at least one of these features.

[0031] Please refer to Figures 1 to 3 The satellite switching method for the NTN high-orbit and low-orbit integrated network according to the embodiment of the present invention includes steps S1 to S3.

[0032] Step S1, setting candidate satellite list stage: After establishing a stable connection with the source satellite, the UE obtains its own position through GNSS and reports it to the source satellite, and obtains the list of candidate satellites allowed to access and measurement configuration from the source satellite.

[0033] As an implementation manner, the source satellite classifies each UE connected to the source satellite into service classes according to the service used, and presets a candidate satellite for each UE.

[0034] The source satellite informs the candidate satellites of the UE's location, movement direction, and service level, and applies to the candidate satellites for UE access. After receiving confirmation from the candidate satellites, the source satellite collects and organizes the confirmation information of all candidate satellites and sends a list of candidate satellites allowed to access and measurement configuration to the UE. The measurement configuration includes measurement trigger conditions and measurement thresholds.

[0035] Step S2, UE measurement phase: 1) After receiving the candidate satellite list, the UE starts measurement and updates the candidate satellite list according to the measurement results.

[0036] a. The UE obtains GNSS (Global Navigation Satellite System) information to predict its trajectory and position coordinates for the future. Combined with the currently measured signal quality, it calculates the ideal signal quality for each candidate satellite for the future and filters out satellites that do not meet the signal quality threshold.

[0037] b. By obtaining the candidate satellite ephemeris and beam center information, predicting the candidate satellite beam center position after a period of time, calculating the distance between the UE and the candidate satellite beam center after a period of time, and filtering out satellites that exceed the distance threshold;

[0038] c. Organize and update the candidate satellite list that meets your needs.

[0039] 2) At the same time, the UE further updates its own candidate satellite list by obtaining the real-time broadcast of the source satellite on the changes of candidate satellites.

[0040] a. The source satellite regularly shares the UE's location information with all candidate satellites. Candidate satellites monitor the UE using this location information, combined with previously received service level information, to determine whether the UE can be handed over. For example, a candidate satellite may have reached its maximum throughput and cannot accommodate new UEs; its available bandwidth may have decreased, changing the types of services it can accommodate; or the UE and candidate satellite may be moving in opposite directions and moving away from each other.

[0041] b. When the above changes occur, the candidate satellite sends the changed status to the source satellite. The source satellite broadcasts the ephemeris information, remaining available channels, acceptable UE service types, and remaining service time of each candidate satellite in the broadcast message;

[0042] c. The UE deletes and updates its list of candidate satellites based on the broadcast information of the source satellite to ensure that the candidate satellites are always accessible and avoid handover access failures.

[0043] Please refer to Figure 2 The specific process is:

[0044] The UE obtains the measurement configuration and candidate satellite list sent from the source satellite;

[0045] The UE performs measurement to obtain the signal quality at the current time t;

[0046] The UE obtains GNSS information to obtain the current position, moving direction and speed information. Combined with the current signal quality, it predicts and calculates the ideal signal quality RSRQ(t+Δt)_ideal of each candidate satellite in the future period Δt, that is, at time t+Δt. It then determines whether RSRQ(t+Δt)_ideal ≥ the preset signal quality threshold. If not, the satellite is discarded. If so, the beam is added to the candidate satellite list.

[0047] The UE obtains the ephemeris and beam center information of each candidate satellite in the candidate satellite list, predicts and calculates the distance d(t+Δt)_ideal from the UE to the beam center of each candidate satellite, and determines whether (t+Δt)_ideal is less than the preset distance threshold. If not, the satellite is discarded. If so, the beam is added to the candidate satellite list;

[0048] UE organizes and updates the candidate satellite list;

[0049] The UE further updates the candidate satellite list based on the candidate satellite information broadcast by the source satellite.

[0050] Step S3, switching decision phase: the UE measures all satellites in the updated candidate satellite list; sorts the low earth orbit satellites and geostationary orbit satellites that meet the conditions according to the measurement results and candidate satellite information, and switches to the most suitable satellite according to the sorting results.

[0051] As an implementation method, a. The UE determines its own service level. If the service has a low latency tolerance, it proceeds to the next step. If the service has a high latency tolerance, it weights and ranks GEO and LEO satellites based on parameters such as communication latency and satellite load.

[0052] b. For UEs with low latency tolerance, sort the remaining LEO satellites in the order of RSRQ, distance from the UE to the satellite beam center, and remaining satellite service time;

[0053] c. The UE periodically performs measurements. When the candidate satellite list is updated in step S2, the updated list needs to be reordered. When a handover occurs, the UE preferentially initiates a handover to the satellite ranked first.

[0054] As an implementation method, a method for sorting GEO satellites and LEO satellites is as follows:

[0055] Step S31, candidate satellite parameter collection and preprocessing:

[0056] The collected parameters include: communication delay D , in milliseconds (ms); satellite load L, in percentage (%); Reference Signal Received Quality (RSRQ), in decibels (dB); Distance from UE to satellite beam center R , in kilometers (km); satellite service time T , in seconds (s)

[0057] Normalize the parameters:

[0058] Positive indicators (RSRQ, service time T ): ;

[0059] Negative indicators (communication delay D, load L, distance R): ;

[0060] in, x ij For the i Satellite j Item parameter value, min( x j )、max( x j ) is the first among all candidate satellites j The minimum and maximum values ​​for the item parameter.

[0061] Step S32, calculate the information entropy of each parameter:

[0062] Compute the probability distribution for the normalized parameters: (like z ij =0, then correct to 10 -6 to avoid calculation errors);

[0063] Calculate the information entropy of each parameter e j : ;

[0064] in, n is the total number of candidate satellites, e j ∈[0,1]; For the i Satellite j The probability distribution of the parameters after normalization.

[0065] Step S33, dynamically determine parameter weights:

[0066] Calculate the objective weight of each parameter based on information entropy: ;

[0067] in m =5, corresponding to the five parameters of communication delay, load, RSRQ, distance, and service duration.

[0068] Step S34, calculate the comprehensive score and sort:

[0069] Calculate a weighted comprehensive score for each candidate satellite: ;

[0070] according to S i Sort the candidate satellites from high to low, and select the satellite with the highest score as the primary service node.

[0071] The present invention can be directly applied to UE in NTN high-low orbit integrated network. The CHO switching process of UE switching from source satellite to LEO satellite is as follows: Figure 3 shown.

[0072] The satellite switching system for the NTN high-orbit and low-orbit integrated network according to an embodiment of the present invention includes:

[0073] Reporting module: After establishing a connection with the source satellite, the UE obtains its own position through GNSS and reports it to the source satellite, and obtains the list of candidate satellites allowed to access and measurement configuration from the source satellite;

[0074] Measurement update module: After receiving the candidate satellite list, the UE starts measurement and updates the candidate satellite list based on the measurement results;

[0075] Sorting and switching module: The UE measures all satellites in the updated candidate satellite list; sorts the low-Earth orbit satellites and geostationary orbit satellites that meet the conditions based on the measurement results and candidate satellite information, and switches satellites based on the sorting results.

[0076] As an implementation method, the source satellite classifies each UE connected to the source satellite into service levels according to the service used, and presets candidate satellites for each UE; the source satellite informs the candidate satellite of the UE's position, movement direction and service level, and applies to the candidate satellite for UE access. After obtaining confirmation from the candidate satellite, the source satellite collects and organizes the confirmation status of all candidate satellites, and sends a list of candidate satellites allowed to access and a measurement configuration to the UE, where the measurement configuration includes a measurement trigger condition and a measurement threshold.

[0077] As an implementation method, the measurement update module updates the candidate satellite list according to the following steps:

[0078] The UE obtains the measurement configuration and candidate satellite list sent from the source satellite;

[0079] The UE performs measurement to obtain the signal quality at the current moment;

[0080] The UE obtains GNSS information to obtain the current position, movement direction, and speed information. Combined with the current signal quality, it predicts and calculates the ideal signal quality of each candidate satellite in the candidate satellite list for a period of time in the future, and eliminates satellites that do not meet the signal quality threshold.

[0081] The UE obtains the ephemeris and beam center information of each candidate satellite in the candidate satellite list, predicts the position of the candidate satellite beam center in the future, calculates the distance between the UE and the beam center of each candidate satellite in the future, and eliminates satellites that exceed the preset distance threshold;

[0082] UE organizes and updates the candidate satellite list;

[0083] The UE further updates the candidate satellite list based on the candidate satellite information broadcast by the source satellite.

[0084] As an implementation method, the measurement update module further updates the candidate satellite list according to the following steps:

[0085] The source satellite regularly shares the UE's location information with all candidate satellites. The candidate satellites determine whether the UE can be handed over based on the UE's location information. If there is a change, the candidate satellites send the changed information to the source satellite.

[0086] The source satellite broadcasts the ephemeris information, remaining available channels, acceptable UE service types, and remaining service time of each candidate satellite in the broadcast message;

[0087] The UE deletes and updates its own list of candidate satellites based on the broadcast information of the source satellite to ensure that the candidate satellites are always accessible and avoid handover access failure.

[0088] As an implementation method, the sorting switching module determines the UE's own service level. If the delay tolerance is high, the low earth orbit satellites and geostationary orbit satellites are weighted and sorted according to the communication delay and satellite load.

[0089] If the service has low latency tolerance, for UEs with low latency tolerance, the remaining low-Earth orbit satellites are sorted in the order of reference signal reception quality, distance from the UE to the satellite beam center, and remaining satellite service time;

[0090] Perform periodic measurements. When the candidate satellite list is updated, reorder the updated candidate satellite list. When a switch occurs, initiate a switch to the satellite that ranks first.

[0091] As an embodiment, the sorting switching module sorts the low earth orbit satellites and the geostationary orbit satellites according to the following steps:

[0092] Candidate satellite parameter collection and preprocessing: Collect candidate satellite parameters, including communication delay D , in milliseconds; satellite load L , in percentage; reference signal reception quality, in decibels; distance from UE to satellite beam center R , in kilometers; satellite service time T , in seconds;

[0093] Reference signal reception quality, satellite service duration T Process according to the following formula:

[0094] ;

[0095] The communication delay D, satellite load L, and distance R from the UE to the satellite beam center are processed according to the following formula:

[0096] ;

[0097] in, x ij For the i Satellite j Item parameter value, min( x j )、max( x j ) is the first among all candidate satellites j The minimum and maximum values ​​of the item parameters, For the i Satellite j Parameters after standardization;

[0098] Calculate the information entropy of each parameter:

[0099] Calculate the probability distribution of each standardized parameter : ;

[0100] Calculate the information entropy of each parameter e j : ;

[0101] in, n is the total number of candidate satellites, i∈n, e j ∈[0,1] ;

[0102] Dynamically determine parameter weights:

[0103] Calculate the objective weight of each parameter based on information entropy: ;

[0104] inm =5, corresponding to communication delay D, satellite load L, reference signal reception quality, distance R from UE to satellite beam center, and satellite service time T Five parameters;

[0105] Calculate the comprehensive score and sort:

[0106] Calculate a weighted comprehensive score for each candidate satellite: ;

[0107] according to S i Sort the candidate satellites from high to low, and select the satellite with the highest score as the primary service node.

[0108] The present invention realizes dynamic updating of candidate lists through real-time information interaction between source satellites (base stations are arranged on satellites) and candidate space-based access points such as low earth orbit (LEO) satellites or geostationary earth orbit (GEO) satellites, periodically obtaining satellite load, remaining service time and beam coverage changes, and optimizing the candidate list by allowing user equipment (UE) to autonomously predict future signal quality and distance changes. In combination with the trajectory prediction of the Global Navigation Satellite System (GNSS) and satellite ephemeris data, the ideal reference signal reception quality (RSRQ) of each candidate satellite in the future period is dynamically calculated. The system uses the signal quality (RSRQ) value and beam center distance trends to select satellites that meet signal quality thresholds and distance constraints in real time, thereby more accurately selecting candidate satellites and preventing UEs from handing over to inaccessible or resource-deficient satellites. Furthermore, it comprehensively considers five key parameters: communication latency, satellite load, RSRQ, UE-to-beam center distance, and service duration. It uses the entropy weighting method to dynamically calculate the objective weights of each parameter, generate a comprehensive score, and then rank them, achieving the global optimal selection of high- and low-orbit satellites. Furthermore, based on the UE's service delay tolerance (ITU-T G.1010 standard), a service-level-driven differentiated handover strategy is adopted. For delay-sensitive services, low-latency LEO satellites are prioritized (sorted by RSRQ, distance, and service duration). For delay-tolerant services, LEO or GEO satellites are balanced based on the entropy weighting method. This method improves the success rate of conditional handovers for UEs and communication continuity, dynamically reduces handover decision delays and signaling interaction load, and fully leverages the synergistic advantages of LEO's low latency and GEO's wide coverage.

[0109] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A satellite switching method for a NTN high-orbit and low-orbit integrated network, characterized in that: include: Step S1: After establishing a connection with the source satellite, the UE obtains its own position through GNSS and reports it to the source satellite, and obtains a list of candidate satellites allowed to access and measurement configuration from the source satellite; Step S2: After receiving the candidate satellite list, the UE starts measurement and updates the candidate satellite list according to the measurement results; Step S3: The UE measures all satellites in the updated candidate satellite list; sorts the low-Earth orbit satellites and geostationary orbit satellites that meet the conditions based on the measurement results and the candidate satellite information, and switches the satellites based on the sorting results; In step S2, the candidate satellite list is updated according to the following steps: The UE obtains the measurement configuration and candidate satellite list sent from the source satellite; The UE performs measurement to obtain the signal quality at the current moment; The UE obtains GNSS information to obtain the current position, movement direction, and speed information. Combined with the current signal quality, it predicts and calculates the ideal signal quality of each candidate satellite in the candidate satellite list for a period of time in the future, and eliminates satellites that do not meet the signal quality threshold. The UE obtains the ephemeris and beam center information of each candidate satellite in the candidate satellite list, predicts the position of the candidate satellite beam center in the future, calculates the distance between the UE and the beam center of each candidate satellite in the future, and eliminates satellites that exceed the preset distance threshold; UE organizes and updates the candidate satellite list; The UE further updates the candidate satellite list based on the candidate satellite information broadcast by the source satellite; In step S3, the UE determines its own service level. If the delay tolerance is high, the UE calculates and sorts the low-Earth orbit satellites and geostationary orbit satellites based on the communication delay and satellite load. If the service has low latency tolerance, for UEs with low latency tolerance, the remaining low-Earth orbit satellites are sorted in the order of reference signal reception quality, distance from the UE to the satellite beam center, and remaining satellite service time; The UE performs measurements periodically and reorders the candidate satellite list when it is updated. When a handover occurs, the UE first initiates a handover to the satellite that is ranked first.

2. The satellite switching method for the NTN high-orbit and low-orbit integrated network according to claim 1, characterized in that: In step S1, the source satellite classifies each UE connected to the source satellite according to the service used according to the service level standard, and presets a candidate satellite for each UE; The source satellite informs the candidate satellites of the UE's location, movement direction, and service level, and applies to the candidate satellites for UE access. After receiving confirmation from the candidate satellites, the source satellite collects and organizes the confirmation information of all candidate satellites and sends a list of candidate satellites allowed to access and measurement configuration to the UE. The measurement configuration includes measurement trigger conditions and measurement thresholds.

3. The satellite switching method for the NTN high-orbit and low-orbit integrated network according to claim 1, characterized in that: In step S2, the candidate satellite list is further updated according to the following steps: The source satellite regularly shares the UE's location information with all candidate satellites. The candidate satellites determine whether the UE can be handed over based on the UE's location information. If there is a change, the candidate satellites send the changed information to the source satellite. The source satellite broadcasts the ephemeris information, remaining available channels, acceptable UE service types, and remaining service time of each candidate satellite in the broadcast message; The UE deletes and updates its own list of candidate satellites based on the broadcast information of the source satellite to ensure that the candidate satellites are always accessible and avoid handover access failure.

4. The satellite switching method for the NTN high-orbit and low-orbit integrated network according to claim 1, characterized in that: In step S3, the low earth orbit satellites and geostationary orbit satellites are sorted according to the following steps: Step S31, candidate satellite parameter collection and preprocessing: Collect candidate satellite parameters, including: communication delay D , in milliseconds; satellite load L , in percentage; reference signal reception quality, in decibels; distance from UE to satellite beam center R , in kilometers; satellite service time T , in seconds; Normalize the parameters: Reference signal reception quality, satellite service duration T Process according to the following formula: ； The communication delay D, satellite load L, and distance R from the UE to the satellite beam center are processed according to the following formula: ； in, x ij For the i Satellite j Item parameter value, min( x j )、max( x j ) is the first among all candidate satellites j The minimum and maximum values ​​of the item parameters, For the i Satellite j Parameters after standardization; Step S32, calculate the information entropy of each parameter: Calculate the probability distribution of each standardized parameter : ; Calculate the information entropy of each parameter e j : ; in, n is the total number of candidate satellites, i∈n, e j ∈[0,1] ; Step S33, dynamically determine parameter weights: Calculate the objective weight of each parameter based on information entropy: ; in m =5, corresponding to communication delay D, satellite load L, reference signal reception quality, distance R from UE to satellite beam center, and satellite service time T Five parameters; Step S34, calculate the comprehensive score and sort: Calculate a weighted comprehensive score for each candidate satellite: ; according to S i Sort the candidate satellites from high to low, and select the satellite with the highest score as the primary service node.

5. A satellite switching system for NTN high-orbit and low-orbit integrated network, characterized in that: include: Reporting module: After establishing a connection with the source satellite, the UE obtains its own position through GNSS and reports it to the source satellite, and obtains the list of candidate satellites allowed to access and measurement configuration from the source satellite; Measurement update module: After receiving the candidate satellite list, the UE starts measurement and updates the candidate satellite list based on the measurement results; Sorting and switching module: The UE measures all satellites in the updated candidate satellite list; sorts the low-Earth orbit satellites and geostationary orbit satellites that meet the conditions based on the measurement results and candidate satellite information, and switches satellites based on the sorting results; The measurement update module updates the candidate satellite list according to the following steps: The UE obtains the measurement configuration and candidate satellite list sent from the source satellite; The UE performs measurement to obtain the signal quality at the current moment; The UE obtains GNSS information to obtain the current position, movement direction, and speed information. Combined with the current signal quality, it predicts and calculates the ideal signal quality of each candidate satellite in the candidate satellite list for a period of time in the future, and eliminates satellites that do not meet the signal quality threshold. The UE obtains the ephemeris and beam center information of each candidate satellite in the candidate satellite list, predicts the position of the candidate satellite beam center in the future, calculates the distance between the UE and the beam center of each candidate satellite in the future, and eliminates satellites that exceed the preset distance threshold; UE organizes and updates the candidate satellite list; The UE further updates the candidate satellite list based on the candidate satellite information broadcast by the source satellite; The sorting and switching module determines the UE's own service level. If the delay tolerance is high, it calculates the weights and sorts the low-Earth orbit satellites and geostationary orbit satellites based on the communication delay and satellite load. If the service has low latency tolerance, then for UEs with low latency tolerance, the remaining low-Earth orbit satellites are sorted in the order of reference signal reception quality, distance from the UE to the satellite beam center, and remaining satellite service time; Perform periodic measurements, and when the candidate satellite list is updated, reorder the updated candidate satellite list; When a switch occurs, the switch is initiated to the satellite that is ranked first.

6. The satellite switching system for the NTN high-orbit and low-orbit integrated network according to claim 5, characterized in that: The sorting switching module sorts low earth orbit satellites and geostationary orbit satellites according to the following steps: Candidate satellite parameter collection and preprocessing: Collect candidate satellite parameters, including communication delay D , in milliseconds; satellite load L , in percentage; reference signal reception quality, in decibels; distance from UE to satellite beam center R , in kilometers; satellite service time T , in seconds; Reference signal reception quality, satellite service duration T Process according to the following formula: ； The communication delay D, satellite load L, and distance R from the UE to the satellite beam center are processed according to the following formula: ； in, x ij For the i Satellite j Item parameter value, min( x j )、max( x j ) is the first among all candidate satellites j The minimum and maximum values ​​of the item parameters, For the i Satellite j Parameters after standardization; Calculate the information entropy of each parameter: Calculate the probability distribution of each standardized parameter : ; Calculate the information entropy of each parameter e j : ; in, n is the total number of candidate satellites, i∈n, e j ∈[0,1] ; Dynamically determine parameter weights: Calculate the objective weight of each parameter based on information entropy: ; in m =5, corresponding to communication delay D, satellite load L, reference signal reception quality, distance R from UE to satellite beam center, and satellite service time T Five parameters; Calculate the comprehensive score and sort: Calculate a weighted comprehensive score for each candidate satellite: ; according to S i Sort the candidate satellites from high to low, and select the satellite with the highest score as the primary service node.

Images