Condition switching method for satellite-ground convergence network

Abstract

The invention discloses a condition switching method for a satellite-ground convergence network, and belongs to the field of wireless communication. Aiming at the problem that the switching failure rate is high due to the fact that a ground switching strategy is used in satellite-ground converged communication, the invention provides a conditional switching method adaptive to target base station selection by analyzing the influence of frequent switching and unnecessary switching times increase caused by high-speed movement of a satellite on a conditional switching strategy. In a switching preparation stage, defining a measurement event based on a receiving power change rate to screen candidate base stations, and generating three candidate base station lists; in the switching execution stage, a dual execution event based on multi-attribute weighting is defined, a target base station is selected based on the three candidate base station lists, and after the base stations in the candidate lists meet the first execution event, the target base station is selected according to a second execution event weighted by the receiving power change rate, the user speed and the load balance degree. The provided condition switching method can effectively reduce the switching frequency and the failure rate, and load balancing between the base stations is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless communication and specifically relates to a conditional switching method for a satellite-ground fusion network. Background Art

[0002] Satellite-Terrestrial Integrated Networks (STIN) use satellites to expand ground communication networks. They have the advantages of large ground network capacity and wide satellite network coverage. They can cope with ubiquitous communication needs and massive data growth, and are the inevitable development trend of future mobile communication networks. However, on the one hand, the LEO satellites in STIN orbit the earth at a speed of up to 7000m / s, and the visible time between user terminals and LEO satellites is only a few minutes. On the other hand, due to the very limited coverage of ground base stations, their service time to terminals is also very short. Therefore, terminals must frequently switch to maintain communication continuity, and it is crucial to design a reasonable switching strategy for terminals under STIN.

[0003] Although conditional switching is a key method proposed by 3GPP to solve the handover management of non-terrestrial networks, it can prepare for handover in advance when the quality of the user's current service cell is good. The simplest conditional switching based on A3 measurement events can solve the high link failure rate and handover failure rate caused by the use of conventional handover procedures in non-terrestrial networks. However, this solution doubles the unnecessary handover rate and PP handover rate, and the number of handovers increases sharply. In order to solve this problem, 3GPP proposed that different trigger conditions can be considered in the measurement events of conditional switching, such as the joint consideration of A3 events and terminal locations. However, among the several trigger conditions proposed by 3GPP, except for the trigger event based on RSRP, the trigger events of the remaining conditions require the user terminal to have positioning capabilities and obtain accurate ephemeris data, which brings certain difficulties to the use of conditional switching for some terminals in STIN that do not have positioning capabilities and when the ephemeris data is expired. Since there is more than one type of base station in STIN, in addition to considering the measurement events in the above conditional switching, it is also necessary to consider which base station to access based on the characteristics of different base stations.

[0004] In summary, the present invention proposes a conditional switching method for a satellite-ground fusion network. First, the measurement events and execution conditions in the conditional switching process are designed, and then the types of base stations that users can switch to in the STIN are classified, and different switching trigger events are selected according to the characteristics of different base stations. This strategy jointly considers the RSRP received by the user, the RSRP change rate, the terminal speed, and the base station load rate to select the base station to improve the switching performance. The present invention ensures the user experience in the satellite-ground fusion network, effectively reduces the number of switching times and the switching failure rate, and also takes into account the load balancing between base stations. Summary of the invention

[0005] The present invention aims to solve the above problems of the prior art. A conditional switching method for a satellite-ground fusion network is proposed. The technical solution of the present invention is as follows:

[0006] A conditional switching method for a satellite-ground fusion network, characterized in that it comprises the following steps:

[0007] S1: The user periodically measures the current environment information, including the received signal power RSRP;

[0008] S2: When there is a base station that satisfies the measurement event based on the RSRP change rate, the user sends a measurement report to the source base station, requesting conditional switching to the base station;

[0009] S3: adding the base station node receiving the conditional switching request to the user's candidate base station list and reserving resources for the user;

[0010] S4: Determine the type of the user's candidate base station list, and configure different execution events for three base stations of different types;

[0011] S5: The user executes the switch to the base station that meets the execution conditions, and releases the resources of the remaining base station nodes in the candidate base station list.

[0012] Furthermore, the RSRP that can be measured by the user in step S1 is:

[0013] RSRP=P s +G s +G u -L (1)

[0014] Among them, P s is the beam transmission power; G s is the antenna gain; G u is the user antenna gain; L is the free space transmission loss, expressed as:

[0015] L=32.45+20lgd+20lgf (2)

[0016] Where f is the carrier frequency; d is the distance between the user and the ground / satellite base station, expressed as:

[0017]

[0018] Where (x u ,y u ),(x b ,y b ) are the coordinates of user u and base station b respectively. According to the relationship between d and the coverage radius of the ground / satellite base station, the coverage matrix C(t) of the ground / satellite base station to the user terminal can be constructed as follows:

[0019]

[0020] Among them, c nm (t) represents user u m With base station b n The coverage relationship between them. ij When (t) = 1, it means user u j At base station b i Within the coverage area, b i May become user u j candidate base station, otherwise when c ij When (t) = 0, it means that user u j Not at base station b i Within the coverage area, b i Cannot be used for user u j candidate base stations; although a user may have more than one accessible candidate base station at a certain moment, it can only select one of them for connection; the connection matrix X(t) is used to reflect the connection relationship between each base station and the user at time t;

[0021]

[0022] Among them, x nm (t) represents user u m With base station b n The connection relationship between them. ij When (t) = 1, it means user u j Currently connected to base station b i , on the contrary, when x ij When (t) = 0, it means that user u j Not connected to base station b i ;

[0023] For base station b i , the number of users accessing is expressed as The following constraints are met:

[0024]

[0025] Among them, κ i represents base station b i The number of channels;

[0026] For users, at most they are switched to one base station:

[0027]

[0028] Furthermore, the measurement event based on the A3 event of the conditional switching in step S2 can be expressed as:

[0029] P T (t)>P S (t)+HOM (8)

[0030] Among them, P T (t) is the RSRP of the target base station, P S (t) is the RSRP of the current base station. The A3 event is based on the reference signal received power. When P T (t) than P S (t) is higher than HOM dB and meets the duration TTT trigger, HOM is set to a negative value in the measurement event to facilitate early start condition switching;

[0031] The measurement events based on the RSRP rate of change are defined as follows:

[0032] P T (t)>P S (t)+HOM+RSRQ CR (9)

[0033] Among them, RSRQ CR is the received signal power change rate based on user measurement, expressed as:

[0034]

[0035] Among them, RSRQ t is the received signal strength at time t; RSRQ t+Δt is the received signal power at time t+Δt; Δt is the event step length; when user u j At base station b i When the user is within the coverage of the source base station and meets the measurement event based on the RSRP change rate, the user will send a measurement report to the source base station.

[0036] Furthermore, in step S3, user u j After sending the measurement report, the base stations that accept the conditional handover constitute the user's candidate base station list. The base stations in the candidate list will reserve resources for the user. The list is expressed as:

[0037]

[0038] For base station b i , the number of users covered is expressed as Because the number of candidate base stations for conditional switching is at most 8 at the same time, the number of base stations that the user can choose to switch to is

[0039] Furthermore, in step S4, base stations are divided into three types according to the user candidate base station list: pure ground base stations, pure satellite base stations and ground / satellite base stations, and the corresponding execution events are execution event 1, execution event 2 and execution event 3. Execution events 1 to 3 are expressions that select different attributes for weighting according to the characteristics of their corresponding base stations.

[0040] The general execution events in conditional switching are defined as follows:

[0041] P T (t)>P S (t)+oCHO S,T (12)

[0042] Among them, oCHO S,T It is a specific offset at which the conditional switch is executed.

[0043] Furthermore, in step S4, for the three different execution events (1-3) corresponding to the three base stations, the execution events of the conditional switching are divided into two layers, namely the first execution event and the second execution event. The first execution event is common to the three base stations, similar to formula (9), and is defined as follows:

[0044] P T (t)>P S (t)+P r (13)

[0045] Among them, P r The power offset can be set. Different from the measurement event, the P r It is set to a positive value because the execution event is used to select the target base station for handover, while the measurement event is used to prepare a candidate base station set.

[0046] Furthermore, in step S4, in addition to the first execution event, the pure ground base station, the pure satellite base station and the ground

[0047] / The second execution event corresponding to the satellite base station is different, which is determined by the RSRP change rate RSRQ CR , base station load factor L i (t) and user speed U v(t) consists of three attributes; among them, RSRQ CR Defined as formula (7), L i (t) is defined as the ratio of the number of users currently connected to the base station to the maximum number of users allowed to access:

[0048]

[0049] User speed U v (t) is defined as follows:

[0050]

[0051] Where ν represents the actual speed of the user, V t represents an adjustable speed reference value, u(ν-V t ) is a step function.

[0052] Furthermore, in step S4, the second execution event of the execution event 1 corresponding to the pure ground base station can be expressed as:

[0053] w 11 RQ CR +w 12 L i (t)+w 13 U v (t)(16) The second execution event of execution event 2 corresponding to the pure satellite base station can be expressed as:

[0054] w 21 RQ CR +w 22 L i (t)(17) The second execution event of execution event 3 corresponding to the ground / satellite base station can be expressed as:

[0055] w 31 RQ CR +w 32 L i (t)+w 33 U v (t)(18) In the above formula, w ij Represents the weight of the attribute, obtained by the entropy weight method, w ij The i in represents the i-th execution event, and j represents the j-th attribute.

[0056] Furthermore, in step S5, after the user classifies the base stations, he determines the execution events that meet the user's current candidate base station set, and then calculates the comprehensive evaluation value of multiple attributes of each candidate base station in the candidate base station set through the entropy weight method. Finally, under the condition of satisfying the first execution event, the candidate base station with the smallest comprehensive value is selected as the destination base station for conditional switching; after switching to the target base station, the user will release the resources reserved by the remaining base station nodes in the candidate base station list.

[0057] The advantages and beneficial effects of the present invention are as follows:

[0058] The method of the present invention proposes a conditional switching method for satellite-ground fusion network by targeting the problem that the high-speed movement of low-orbit satellites in STIN causes frequent switching of user terminals and the switching performance cannot be effectively guaranteed. The main innovation of the present invention is to propose a measurement event based on the RSRP change rate and a dual execution event based on base station classification, so as to switch to a base station with better performance. In existing research, the switching program of the ground network applied to STIN will result in a high switching failure rate. Although the conditional switching program can solve this problem, it will greatly increase unnecessary switching and the total number of switching. In response to this problem, the solution proposed by 3GPP is to take different trigger conditions into account in the measurement event of conditional switching. However, among the several trigger conditions proposed by 3GPP, except for the trigger event based on RSRP, the trigger events of the remaining conditions require the user terminal to have positioning capabilities and obtain accurate ephemeris data, which brings certain difficulties to some terminals in STIN that do not have positioning capabilities and use conditional switching when the ephemeris data is expired. Based on this, the present invention proposes to add an RSRP change rate that can represent the relative position of the user and the base station to a certain extent to the measurement event of the conditional switching, which can make it possible to use conditional switching to ensure the success of the switching while reducing the number of switching times regardless of whether the user terminal has positioning capability and whether the ephemeris data is accurate, which reflects the rationality and practicality of the present invention. In addition, there is currently a lack of research on execution events in conditional switching, and the role of execution events is to select the target base station for switching, which is very important. In addition, there is more than one type of base station in STIN, which leads to the need to be more cautious in formulating the standards for execution events. Therefore, the present invention proposes a dual execution event based on base station classification, and formulates different execution events for different base station types. In the execution event, the attribute of base station load balancing is added, so that the utilization rate of the base station can be maximized while ensuring the switching performance. In addition, the present invention adds the attribute of user speed to the execution event. The consideration of user speed is mainly because the switching of the ground network is too sensitive to the attribute of speed. When a terminal with too high speed switches in the ground network, the number of switching will increase significantly, and the switching failure rate will also increase significantly, while the terminal speed has almost no effect on the switching of the satellite network. The proposed dual execution events based on base station classification make the present invention more adaptable to STIN and make up for the lack of research on execution events in conditional switching to a certain extent, reflecting the uniqueness and creativity of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 This is a satellite-ground fusion network architecture diagram of a preferred embodiment provided by the present invention;

[0060] Figure 2 A flow chart of conditional switching is provided for the present invention;

[0061] Figure 3 The present invention is a schematic flow chart of a conditional switching method for a satellite-ground fusion network. DETAILED DESCRIPTION

[0062] The following will describe the technical solutions in the embodiments of the present invention in detail in conjunction with the accompanying drawings in the embodiments of the present invention. The described embodiments are only part of the embodiments of the present invention.

[0063] The technical solution of the present invention to solve the above technical problems is:

[0064] 1. Network Model

[0065] The main research scenario of the present invention is the satellite-ground integrated network (STIN). STIN includes ground gateways, low-orbit satellites and high-orbit satellites. With satellite networks and ground networks as the backbone, they are jointly composed of deep space networks and near-space networks for low-latency, long-distance, and high-throughput data transmission. The satellite-ground integrated network uses the advantages of satellite networks to provide bandwidth access to the world and realize global three-dimensional seamless coverage network services. The satellite-ground integrated network can not only expand network coverage capabilities, ensure business continuity, and improve network reliability. In addition, it can also be widely used in earth observation, marine communications, airborne communications, emergency communications, etc.

[0066] 2. Technical solution:

[0067] A conditional switching method for a satellite-ground fusion network, the method comprising:

[0068] S1: The user periodically measures the current environment information, such as the received signal power RSRP;

[0069] S2: When a base station satisfies the measurement event based on the RSRP change rate, the user sends a measurement report to the source base station, requesting conditional switching to the base station;

[0070] S3: adding the base station node receiving the conditional switching request to the user's candidate base station list and reserving resources for the user;

[0071] S4: Determine the type of the user's candidate base station list and configure different execution events for the three different types of base stations;

[0072] S5: The user executes the switch to the base station that meets the execution conditions, and releases the resources of the remaining base station nodes in the candidate base station list.

[0073] First, the RSRP that the user can measure is:

[0074] RSRP=P s +G s +G u -L (1)

[0075] Among them, P s is the beam transmission power; G s is the antenna gain; G u is the user antenna gain; L is the free space transmission loss, expressed as:

[0076] L=32.45+20lgd+20lgf (2)

[0077] Where f is the carrier frequency; d is the distance between the user and the ground / satellite base station, expressed as:

[0078]

[0079] Where (x u ,y u ),(x b ,y b ) are the coordinates of user u and base station b respectively. According to the relationship between d and the coverage radius of the ground / satellite base station, the coverage matrix C(t) of the ground / satellite base station to the user terminal can be constructed as follows:

[0080]

[0081] Among them, c nm (t) represents user u m With base station b n The coverage relationship between them. ij When (t) = 1, it means user u j At base station b i Within the coverage area, b i May become user u j candidate base station, otherwise when c ij When (t) = 0, it means that user u j Not at base station b i Within the coverage area, b i Cannot be used for user u j Although a user may have more than one candidate base station to connect to at a certain moment, it can only select one of them at most for connection. The connection matrix X(t) is used to reflect the connection relationship between each base station and the user at time t.

[0082]

[0083] Among them, x nm (t) represents user u m With base station b n The connection relationship between them. ij When (t) = 1, it means user u j Currently connected to base station b i , on the contrary, when xij When (t) = 0, it means that user u j Not connected to base station b i .

[0084] For base station b i , the number of users accessing is expressed as The following constraints are met:

[0085]

[0086] Among them, κ i represents base station b i The number of channels.

[0087] For users, at most they are switched to one base station:

[0088]

[0089] Then, the measurement event based on the RSRP change rate is defined as follows:

[0090] P T (t)>P S (t)+HOM+RSRQ CR (9)

[0091] Among them, RSRQ CR is the received signal power change rate based on user measurement, expressed as:

[0092]

[0093] Among them, RSRQ t is the received signal strength at time t; RSRQ t+Δt is the received signal power at time t+Δt; Δt is the event step length. j At base station b i When the user is within the coverage of the source base station and meets the measurement event based on the RSRP change rate, the user will send a measurement report to the source base station.

[0094] In user u j After sending the measurement report, the base stations that accept the conditional handover will form the user's candidate base station list. The base stations in the candidate list will reserve resources for the user. The list can be expressed as:

[0095]

[0096] For base station b i , the number of users covered is expressed as Because the number of candidate base stations for conditional switching is at most 8 at the same time, the number of base stations that the user can choose to switch to is

[0097] Since there are two types of satellite-ground fusion networks, ground networks and satellite networks, there may be different types of base stations in the user's candidate base station list. The characteristics of different types of base stations make them need to consider different execution events. Therefore, according to the user's candidate base station list, the base stations are divided into three types: pure ground base stations, pure satellite base stations and ground / satellite base stations. The corresponding execution events are execution event 1, execution event 2 and execution event 3. Execution events 1 to 3 are expressions that select different attributes for weighting according to the characteristics of their corresponding base stations.

[0098] The general execution events in conditional switching are defined as follows:

[0099] P T (t)>P S (t)+oCHO S,T (12)

[0100] Among them, oCHO S,T It is a specific offset when the conditional handover is executed. It can be seen that the execution event definition of the conditional handover is very similar to the A3 event. However, this event is only evaluated for the prepared base stations (the user's candidate base stations); in addition, this event does not generate a measurement report like the A3 event.

[0101] For the three different execution events (1-3) corresponding to the three base stations, the execution events of the conditional switching are divided into two layers, namely the first execution event and the second execution event. The first execution event is common to the three base stations, similar to formula (9), and is defined as follows:

[0102] P T (t)>P S (t)+P r (13)

[0103] Among them, P r is a configurable power offset. r It is generally set to a positive value because the execution event is used to select the target base station for handover, while the measurement event is used to prepare a candidate base station set.

[0104] In addition to the first execution event, the second execution events corresponding to the pure ground base station, the pure satellite base station and the ground / satellite base station are different, which are determined by the RSRP change rate RSRQ CR , base station load factor L i (t) and user speed U v (t) consists of three attributes. Among them, RSRQ CR Defined as formula (7), L i(t) is defined as the ratio of the number of users currently connected to the base station to the maximum number of users allowed to access:

[0105]

[0106] User speed U v (t) is defined as follows:

[0107]

[0108] Where ν represents the actual speed of the user, V t represents an adjustable speed reference value, u(ν-V t ) is a step function.

[0109] The second execution event of the execution event 1 corresponding to the pure ground base station can be expressed as:

[0110] w 11 RQ CR +w 12 L i (t)+w 13 U v (t)(16) The second execution event of execution event 2 corresponding to the pure satellite base station can be expressed as:

[0111] w 21 RQ CR +w 22 L i (t)(17) The second execution event of execution event 3 corresponding to the ground / satellite base station can be expressed as:

[0112] w 31 RQ CR +w 32 L i (t)+w 33 U v (t)(18)

[0113] In the above formula, w ij Represents the weight of the attribute, obtained by the entropy weight method, w ij The i in represents the i-th execution event, and j represents the j-th attribute.

[0114] After the user passes the base station classification, the execution event that meets the user's current candidate base station set can be determined, and then the comprehensive evaluation value of multiple attributes of each candidate base station in the candidate base station set is calculated by the entropy weight method. Finally, under the condition of satisfying the first execution event, the candidate base station with the smallest comprehensive value is selected as the target base station for conditional switching. After switching to the target base station, the user will release the resources reserved by the remaining base station nodes in the candidate base station list.

[0115] The systems, devices, modules or units described in the above embodiments may be implemented by computer chips or entities, or by products with certain functions.

[0116] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0117] The above embodiments should be understood to be only used to illustrate the present invention and not to limit the protection scope of the present invention. After reading the contents of the present invention, technicians can make various changes or modifications to the present invention, and these equivalent changes and modifications also fall within the scope defined by the claims of the present invention.

Claims

1. A conditional switching method for a satellite-ground fusion network, characterized in that: The following steps are involved: S1: The user periodically measures the current environment information, including the received signal power RSRP; S2: When there is a base station that satisfies the measurement event based on the RSRP change rate, the user sends a measurement report to the source base station, requesting conditional switching to the base station; S3: adding the base station node receiving the conditional switching request to the user's candidate base station list and reserving resources for the user; S4: Determine the type of the user's candidate base station list, and configure different execution events for three base stations of different types; S5: The user executes the switch to the base station that meets the execution conditions, and releases the resources of the remaining base station nodes in the candidate base station list.

2. A conditional switching method for satellite-ground fusion network according to claim 1, characterized in that: The RSRP that the user can measure in step S1 is: RSRP=P s +G s +G u -L (1) Among them, P s is the beam transmission power; G s is the antenna gain; G u is the user antenna gain; L is the free space transmission loss, expressed as: L=32.45+20lgd+20lgf (2) Where f is the carrier frequency; d is the distance between the user and the ground / satellite base station, expressed as: Where (x u ,y u ),(x b ,y b ) are the coordinates of user u and base station b respectively. According to the relationship between d and the coverage radius of the ground / satellite base station, the coverage matrix C(t) of the ground / satellite base station to the user terminal can be constructed as follows: Among them, c nm (t) represents user u m With base station b n The coverage relationship between them is ij When (t) = 1, it means user u j At base station b i Within the coverage area, b i May become user u j candidate base station, otherwise when c ij When (t) = 0, it means that user u j Not at base station b i Within the coverage area, b i Cannot be used for user u j candidate base stations; although a user may have more than one accessible candidate base station at a certain moment, it can only select one of them for connection; the connection matrix X(t) is used to reflect the connection relationship between each base station and the user at time t; Among them, x nm (t) represents user u m With base station b n The connection relationship between them, when x ij When (t) = 1, it means user u j Currently connected to base station b i , on the contrary, when x ij When (t) = 0, it means that user u j Not connected to base station b i ; For base station b i , the number of users accessing is expressed as The following constraints are met: Among them, κ i represents base station b i The number of channels; For a user, at most one base station is switched:

3. A conditional switching method for satellite-ground fusion network according to claim 2, characterized in that: The measurement event based on the A3 event of the conditional switching in step S2 can be expressed as: P T (t)>P S (t)+HOM (8) Among them, P T (t) is the RSRP of the target base station, P S (t) is the RSRP of the current base station. The A3 event is based on the reference signal received power. When P T (t) than P S (t) is higher than HOM dB and meets the duration TTT trigger, HOM is set to a negative value in the measurement event to facilitate early start condition switching; The measurement events based on the RSRP rate of change are defined as follows: P T (t)>P S (t)+HOM+RSRQ CR (9) Among them, RSRQ CR is the received signal power change rate based on user measurement, expressed as: Among them, RSRQ t is the received signal strength at time t; RSRQ t+Δt is the received signal power at time t+Δt; Δt is the event step length; when user u j At base station b i When the user is within the coverage of the source base station and meets the measurement event based on the RSRP change rate, the user will send a measurement report to the source base station.

4. A conditional switching method for satellite-ground fusion network according to claim 3, characterized in that: In step S3, user u j After sending the measurement report, the base stations that accept the conditional handover constitute the user's candidate base station list. The base stations in the candidate list will reserve resources for the user. The list is expressed as: For base station b i , the number of users covered is expressed as Because the number of candidate base stations for conditional switching is at most 8 at the same time, the number of base stations that the user can choose to switch to is 5. A conditional switching method for satellite-ground fusion network according to claim 4, characterized in that: In step S4, base stations are divided into three types according to the user candidate base station list: pure ground base stations, pure satellite base stations and ground / satellite base stations, and the corresponding execution events are execution event 1, execution event 2 and execution event 3. Execution events 1 to 3 are expressions that select different attributes for weighting according to the characteristics of their corresponding base stations; The general execution events in conditional switching are defined as follows: P T (t)>P S (t)+oCHO S,T (12) Among them, oCHO S,T It is a specific offset at which the conditional switch is executed.

6. A conditional switching method for satellite-ground fusion network according to claim 5, characterized in that: In step S4, for the three different execution events (1-3) corresponding to the three base stations, the execution events of the conditional switching are divided into two layers, namely the first execution event and the second execution event. The first execution event is common to the three base stations, similar to formula (9), and is defined as follows: P T (t)>P S (t)+P r (13) Among them, P r The power offset can be set. Different from the measurement event, the P r It is set to a positive value because the execution event is used to select the target base station for handover, while the measurement event is used to prepare a candidate base station set.

7. A conditional switching method for satellite-ground fusion network according to claim 6, characterized in that: In step S4, in addition to the first execution event, the second execution events corresponding to the pure ground base station, the pure satellite base station and the ground / satellite base station are different, and the RSRP change rate RSRQ CR , base station load factor L i (t) and user speed U v (t) consists of three attributes; among them, RSRQ CR Defined as formula (7), L i (t) is defined as the ratio of the number of users currently connected to the base station to the maximum number of users allowed to access: User speed U v (t) is defined as follows: Where ν represents the actual speed of the user, V t represents an adjustable speed reference value, u(ν-V t ) is a step function.

8. A conditional switching method for satellite-ground fusion network according to claim 7, characterized in that: In step S4, the second execution event of the execution event 1 corresponding to the pure ground base station can be expressed as: w 11 RSRQ CR +w 12 L i (t)+w 13 U v (t)(16) The second execution event of the execution event 2 corresponding to the pure satellite base station can be expressed as: w 21 RSRQ CR +w 22 L i (t)(17) The second execution event of execution event 3 corresponding to the ground / satellite base station can be expressed as: w 31 RQ CR +w 32 L i (t)+w 33 U v (t)(18) In the above formula, w ij Represents the weight of the attribute, obtained by the entropy weight method, w ij The i in represents the i-th execution event, and j represents the j-th attribute.

9. A conditional switching method for satellite-ground fusion network according to claim 8, characterized in that: In step S5, after the user classifies the base stations, he determines the execution events that meet the user's current candidate base station set, and then calculates the comprehensive evaluation value of multiple attributes of each candidate base station in the candidate base station set through the entropy weight method. Finally, under the condition of satisfying the first execution event, the candidate base station with the smallest comprehensive value is selected as the destination base station for conditional switching; after switching to the target base station, the user will release the resources reserved by the remaining base station nodes in the candidate base station list.

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