Low earth orbit satellite switching method and system in multi-user scene, and electronic equipment

Abstract

The invention provides a low earth orbit satellite switching method and system in a multi-user scene, and electronic equipment, and aims to solve the technical problems of use scene limitation and high time delay in a traditional multi-attribute switching method. The method comprises the following steps: step 1, reading satellite orbit parameter information Os and setting ground user geographic coordinate points (Pu1, Pu2 and Pu3), a basic time unit tstep, starting time t0 and ending time tN; 2, calculating a pitch angle As, t of each time slot satellite s to a ground user, residual connectable time Ts, t and maximum connectable time # imgabs0 #, and then forming a connectable satellite sequence in all time slots according to screening conditions; step 3, performing low-orbit satellite screening and satellite switching path calculation in a multi-user scene on each time slot; and step 4, selecting the path with the least switching times and distributing the path to the user. According to the method, the switching frequency of ground users in a low-orbit satellite constellation communication system can be reduced, the communication time delay is reduced, the system performance is improved, and the method has a wide application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of satellite communication, and in particular, relates to a low-earth orbit satellite handover method and system, and an electronic device in a multi-user scenario. Background Art

[0002] Large-scale low-earth orbit constellations generally consist of hundreds to thousands of satellites. The data of the ground gateway station received by the satellites is multi-hop forwarded in the satellite network and then transmitted to users to achieve satellite communication. Compared with medium and high orbit satellites, low-earth orbit satellite communication has characteristics such as low latency and flexible resource allocation. With the wide application of reusable rocket technology and the rapid development of communication technology, low-earth orbit satellite communication has been widely applied and has become an important supplementary part of traditional ground networks. Low-earth orbit satellites in satellite networks have characteristics such as large scale, high dynamicity, multiple service types, complex network topology, and large signaling overhead. These characteristics will lead to problems such as increased communication latency, reduced bandwidth, and increased packet loss rate, thus seriously affecting the user experience. Therefore, the handover method and system of low-earth orbit satellites are an important part affecting communication quality. There is a need in this field to develop an efficient and reliable large-scale low-earth orbit constellation satellite handover technology that can improve the reliability of satellite network systems and achieve satellite network load balancing while ensuring the quality of user services.

[0003] Satellite handover methods can be divided into single-attribute handover methods and multi-attribute handover methods. With the continuous development of satellite monitoring technology, ground users can estimate in advance data such as the real-time distance, real-time elevation angle, and maximum connection time of satellites to ground users in each time slot through preloaded ephemeris files. Ground users execute satellite handover methods based on one or more of these attributes to calculate the satellite evaluation function at the current moment and switch to the satellite with the best communication performance.

[0004] Traditional multi-attribute handover methods regard each satellite as a node and select the handover satellite path based on the evaluation function calculated from satellite handover attributes. Such methods are usually applicable to single-user handover scenarios with low satellite dynamicity. However, with the rapid development of low-earth orbit satellite communication technology, multi-user communication in large-scale low-earth orbit constellations has become the mainstream application scenario. Therefore, in such scenarios, this method has a large number of user handovers and high latency, and it is difficult to meet the low-latency requirements for multi-user simultaneous access. Summary of the Invention

[0005] To solve the technical problems of limited application scenarios and high latency in traditional multi-attribute handover methods, the present invention provides a low-earth orbit satellite handover method and system, and an electronic device in a multi-user scenario.

[0006] To solve the technical problems existing in the above-mentioned prior art, the present invention adopts the following technical solutions:

[0007] A low-earth orbit satellite handover method in a multi-user scenario, the specific steps are as follows:

[0008] Step 1: Read the satellite orbit parameter information O s and set the geographical coordinate points of the ground users (P u1 , P u2 , P u3 ), the basic time unit t step , the start time t0 and the end time t N ;

[0009] Step 2: Calculate the elevation angle A of the satellite s to the ground user for each time slot s,t , the remaining connectable time T s,t and the maximum connectable time to form the connectable satellite sequence within all time slots according to the screening conditions;

[0010] Step 3: Perform low-earth orbit satellite screening and satellite handover path calculation under the multi-user scenario for each time slot;

[0011] Step 4: Select the path with the fewest handover times and assign it to the user.

[0012] Preferably, consider a communication system with u users and S low-earth orbit satellites. The geographical coordinate points of the users are (P u1 , P u2 , P u3 ), and the orbit information of the satellites in the constellation in orbit is the set i.e., the Two-Line Element (TLE). The basic time unit is t step , the start time of all user connections is t0, and the end time is t N , the elevation angle of the satellite s to any user in the time slot t is A s,t , the remaining connectable time of the satellite s to any user in the time slot r is T s,t , and the maximum connectable time of the satellite s to any user is where s ∈ {1, …, S}, u ∈ {1, …, U}, r ∈ {t0, t1, …, t N}. The satellite s can only be connected to a single user at any time. The elevation angle threshold for screening connectable satellites is and the maximum connectable time threshold is The number of connectable satellites for any user in the time slot t is k t , and the numbers of the connectable satellites are represented as s a,t , a ∈ {1, 2, …, k t}, t ∈ {t0, t1, …, t N}. For the time slot t, after the system performs satellite handover calculation, there is M t = min{k t , kt-1} satellite switching paths, the number of the satellite switching path is R m,t , the corresponding satellite number switched to is r m,t , the corresponding switching times is H m,t , where m∈{1,2,…,M t}.

[0013] Furthermore, in step 1, each constellation satellite is loaded with and {(P u1 ,P u2 ,P u3 ),u∈{1,2,…,U}}, set the basic time unit t step , set the start time slot t0 according to the current access request time, and set the time slot sequence t according to the duration of the requested connection n =t0+n×t step ,n∈{1,2,…,N}, N is the basic time unit.

[0014] Furthermore, in step 2, the pitch angle calculation function aer is run to calculate the pitch angle A of the satellite s to the user at time slot t. s,t . Increase t from t0 to t N , calculate the A of satellite s s,t The first Time slot The first Time slot Calculate the satellite s in time slot t n The remaining connect time for any user in Calculate the maximum connectable time of satellite s for any user The underlying calculations described in this step are basic mathematical geometry operations, which have been integrated and encapsulated into the matlab program function in the actual simulation process. Enter the satellite orbit parameters and ground user position in matlab and set the time. After calling the function, all the calculation processes described in this step can be implemented. Specifically, Matlab added the aer function in version 2021a. The aer in the function name refers to azimuth angle (satellite azimuth angle), elevation angle (satellite pitch angle) and range (distance). The function is used to calculate these three data of low-orbit satellites for ground stationary users in each time slot, so it is named aer function. This function can calculate the pitch angle A of all satellites to a single user in all time slots. s,t ; Then set the connectable pitch angle threshold, and filter the above-generated pitch angle data to calculate the start connectable time slot and end connectable time slot of each satellite for the user About the remaining connection time Maximum Connectable Time Example of calculation: If the elevation angle data of a certain satellite to a ground user in 5 time slots are 0, 40, 90, 40, 0 (degrees), and the elevation angle threshold is 30 degrees, it can be known that the satellite is connectable in the 2nd to 4th time slots. The start time slot where the elevation angle is first ≥ 30 degrees is the 2nd time slot, and the end time slot where the elevation angle is first < 30 degrees is the 5th time slot. If it is at the start time of the 3rd time slot, the calculation in the third part of this step means that the user only has 5 - 3 = 2 time slots (the 3rd and 4th time slots) left to connect to the satellite, so it is named the remaining connectable time; the calculation in the fourth part of this step means that the satellite can connect to the ground user for at most 5 - 2 = 3 time slots (the 2nd, 3rd, and 4th time slots), so it is named the maximum connectable time, which means the maximum time the satellite can connect to the user under the threshold condition constraint.

[0015] Increase n from 0 to N, for any time slot t n , filter out satellite s as the connectable satellite for time slot t n All the connectable satellites form the connectable satellite sequence for time slot t n

[0016] Initialize the set of disabled satellites

[0017] Furthermore, step 3 is specifically as follows:

[0018] Initialize

[0019] Increase n from 0 to N, and execute the satellite screening calculation in sequence: For any satellite s, if and then update to Update to Increase n ′ from n + 1 to N, if then update to

[0020] For the satellites screened out when n = 0, initialize as the element of , and initialize all elements of to 0. Increase n from 1 to N, and execute the satellite handover path calculation in sequence: Initialize m = 0, and initialize the set For time slot t n in all ​Loop a in ascending order of set elements. If where then set and update to Update to At and form a handover path and update m to m + 1. For time slot t n all Loop a in ascending order of set elements. If and then set where is the minimum value of the set and update to Update to At and form a handover path and update m to m + 1.

[0021] Furthermore, in step 4, the specific method for selecting the handover path is as follows: Select the minimum value from i.e., the minimum number of handovers, and the corresponding The corresponding handover path is the selected handover path. Add the satellite numbers n ∈ {1, 2,..., N} of the selected handover path to the set

[0022] Furthermore, the above steps 3 and 4 are executed cyclically U times, i.e., step 3 is executed for each time slot in turn, and step 4 is executed after step 3 is completed for all N time slots. The U selected handover paths are the handover paths of U users.

[0023] The present invention also discloses a low-earth orbit satellite handover system in a multi-user scenario for executing the above method, including the following modules:

[0024] Setting module: Read satellite orbit parameter information and set the geographical coordinate points of ground users, basic time units, start time, and end time;

[0025] Connectable satellite sequence screening module: Calculate the elevation angle, remaining connectable time, and maximum connectable time of satellites to ground users for each time slot, and form a connectable satellite sequence within all time slots according to the screening conditions;

[0026] Handover path calculation module: Execute low-earth orbit satellite screening and satellite handover path calculation for each time slot in a multi-user scenario;

[0027] Path allocation module: Select the path with the fewest handover times and allocate it to the user.

[0028] The present invention also discloses an electronic device, including:

[0029] A processor;

[0030] A memory for storing a program, which, when called and executed by the processor, causes the processor to execute the above method or system.

[0031] By adopting the technical solution of the present invention, the handover times of ground users in a low-earth orbit satellite constellation communication system can be reduced, the communication delay can be reduced, the system performance can be improved, and it has a wide range of usage scenarios. Description of the Drawings

[0032] Figure 1 It is a flowchart of a low-earth orbit satellite handover method in a multi-user scenario according to a preferred embodiment of the present invention.

[0033] Figure 2 It is a simulation comparison diagram of the handover times of the low-earth orbit satellite handover method in an embodiment of the present invention.

[0034] Figure 3 It is a block diagram of a low-earth orbit satellite handover system in a multi-user scenario according to a preferred embodiment of the present invention. Detailed Embodiments

[0035] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments.

[0036] As Figure 1 shown, in a low-earth orbit satellite handover method in a multi-user scenario of this embodiment, set to be 30 degrees, to be 180 seconds. The specific steps of this method are as follows:

[0037] First step, load the orbital parameters of 6416 low-earth orbit satellites and the geographical coordinates of 4 users (30°18′ north latitude, 120°20′ east longitude, altitude 0 meters) on each constellation satellite, set the basic time unit t step to be 30 seconds, set the start time slot t0 to 09:00:00 on October 10, 2024 according to the current requested access time, and set the time slot sequence t n = t0 + n × t step , n ∈ {1, 2,..., N}.

[0038] Second step, run the elevation angle calculation function to calculate the elevation angle A of satellite s for the user at time slot t s,t . Increase t from t0 to tN , calculate A of satellite s s,t the first one in time slot the first one time slot Calculate the remaining connectable time of satellite s for any user in time slot t n For any user Among them, Calculate the maximum connectable time of satellite s for any user

[0039] Increase n from 0 to N. For any time slot t n , filter out Satellite s as time slot t n Connectable satellite, all connectable satellites form time slot s n Connectable satellite sequence

[0040] Initialize the set of disabled satellites

[0041] Step 3, initialize

[0042] Increase n from 0 to N and perform satellite screening calculations in sequence: For any satellite s, if and Then Update to Set Update to Set n ′ Increase from n + 1 to N. If Then Update to

[0043] For the Satellites screened out when n = 0, set Initialize to Elements of, set All elements of are initialized to 0. Increase n from 1 to N and perform satellite handover path calculations in sequence: Initialize m = 0 and initialize the set For time slot t n All in Loop a in ascending order of set elements. If Among them Then set And update To Update To At and A handover path is formed therebetween, and m is updated to m + 1. For time slot t n all Circulate a in ascending order of set elements. If and then set where is the minimum value of the set and update to be Update to be At and A handover path is formed therebetween, and m is updated to m + 1.

[0044] Step 4: Select a handover path. Select the minimum value from , that is, the minimum number of handovers. The corresponding The corresponding handover path is the selected handover path. Add the satellite numbers n ∈ {1, 2, …, N} of the selected handover path to the set

[0045] In this embodiment, the above Step 3 and Step 4 are executed in a loop 4 times, that is: Step 3 is executed in sequence for each time slot, and after Step 3 is executed for all N time slots, Step 4 is executed. The 4 selected handover paths are the handover paths of 4 users.

[0046] Figure 2 is a simulation comparison diagram of the total number of handovers of all ground users after executing the handover method of this embodiment and the number of handovers of 2 existing traditional greedy handover methods. Among them, handovers is the method adopted in this embodiment, and handoverGS and handoverGP are 2 existing traditional greedy handover methods. It can be seen from this figure that the method of the present invention has fewer handover times and reduces the communication delay.

[0047] As Figure 3 shown, this embodiment discloses a low-earth orbit satellite handover system in a multi-user scenario for executing the above method, including the following modules:

[0048] Setting module: Read satellite orbit parameter information and set the geographical coordinate points of ground users, basic time unit, start time, and end time;

[0049] Connectable satellite sequence screening module: Calculate the elevation angle, remaining connectable time, and maximum connectable time of each satellite to the ground user in each time slot, and form the connectable satellite sequence within all time slots according to the screening conditions;

[0050] Handover path calculation module: Perform low-Earth orbit satellite screening and satellite handover path calculation for each time slot in a multi-user scenario;

[0051] Path allocation module: Select the path with the fewest handover times and allocate it to the user.

[0052] For other content of this embodiment, reference can be made to the above method embodiment.

[0053] The present invention also discloses an electronic device, including:

[0054] A processor;

[0055] A memory for storing a program, which, when called and executed by the processor, causes the processor to execute the above method or system.

[0056] In summary, the present invention provides a low-Earth orbit satellite handover method and system in a multi-user scenario, which solves the problems of limited usage scenarios and high latency in traditional multi-attribute handover methods. The present invention can reduce the handover times of ground users in a low-Earth orbit satellite constellation communication system, reduce communication latency, improve system performance, and has a wide range of usage scenarios.

[0057] The above describes the specific embodiments of the present invention to facilitate those skilled in the art to understand the present invention. However, the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions made using the concept of the present invention are within the scope of protection.

Claims

1. A low-orbit satellite switching method in a multi-user scenario, characterized in that: The specific steps are as follows: Step 1, read the satellite orbit parameter information and set the ground user geographic coordinate point, basic time unit, start time and end time; Step 2: Calculate the satellite elevation angle, remaining connectable time and maximum connectable time for each time slot, and construct a connectable satellite sequence in all time slots according to the screening conditions; Step 3: Perform low-orbit satellite screening and satellite switching path calculation in a multi-user scenario for each time slot; Step 4: Select the path with the least switching times and assign it to the user.

2. The low-orbit satellite switching method in a multi-user scenario as claimed in claim 1, characterized in that: Step 1 is as follows: Load satellite orbit parameter information on each constellation satellite and ground user geographic coordinate point {(P u1 ,P u2 ,P u3 ),u∈{1,2,…,U}}, set the basic time unit t step , set the start time t0 according to the current access request, and set the time slot sequence t according to the duration of the requested connection n =t0+n×t step ,n∈{1,2,…,N}.

3. The low-orbit satellite switching method in a multi-user scenario as claimed in claim 2, characterized in that: In step 2, the elevation angle calculation function aer is used to calculate the elevation angle A of the satellite s to the user at time slot t. s,t ; Increase t from t0 to t N , calculate the A of satellite s s,t The first The start time slot The first End of the slot Calculate the satellite s in time slot t n The remaining connect time for any user in, Calculate the maximum connectable time of satellite s for any user Increasing n from 0 to N, for any time slot t n , filter out The satellite s is used as the time slot t n connectable satellites, all connectable satellites constitute time slot t n Connectable satellite sequence in, Indicates the number of satellites that establish communication connections with ground users; Initialize the disabled satellite set 4. The low-orbit satellite switching method in a multi-user scenario as claimed in claim 3, characterized in that: Step 3 is as follows: Initialization Increase n from 0 to N and perform satellite screening in sequence: For any satellite s, if and Then Updated to Will Updated to n ′ From n+1 to N, if Then Updated to For n = 0 The selected satellites will Initialize to The elements of Initialize all elements of to 0; increase n from 1 to N, and perform satellite switching path calculation in sequence: initialize m = 0, initialize the set For time slot t n All Loop a from small to large elements of the collection. If in, Then set and update for renew for exist and A switching path is formed between them, and m is updated to m+1; for time slot t n All Loop a from small to large elements of the collection. If and Then set in, For collection The minimum value of for renew for exist and A switching path is formed between them, and m is updated to m+1.

5. The low-orbit satellite switching method in a multi-user scenario as claimed in claim 4, characterized in that: In step 4, the switching path is selected as follows: The minimum value selected is the minimum number of switching times, corresponding to The corresponding switching path is the selected switching path; the satellite number of the selected switching path is n∈{1,2,…,N} joins the set 6. The low-orbit satellite switching method in a multi-user scenario according to any one of claims 3 to 5, characterized in that: Step 3 is executed in each time slot in sequence. Step 4 is executed after step 3 is executed in N time slots. The selected U switching paths are the switching paths for U users.

7. A low-orbit satellite switching system in a multi-user scenario, used to execute the method according to any one of claims 1 to 6, characterized in that: Includes the following modules: Setting module: reads satellite orbit parameter information and sets ground user geographic coordinate points, basic time units, start time and end time; Connectable satellite sequence screening module: calculates the satellite's elevation angle to ground users, remaining connectable time and maximum connectable time in each time slot, and constructs connectable satellite sequences in all time slots according to the screening conditions; Switching path calculation module: performs low-orbit satellite screening and satellite switching path calculation in multi-user scenarios for each time slot; Path allocation module: selects the path with the least switching times and allocates it to the user.

8. An electronic device, characterized in that: include: processor; A memory for storing a program, wherein when the program is called and executed by a processor, the processor executes the method according to any one of claims 1 to 6 or the system according to claim 7.

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