A method for maintaining a ground gateway feeder link based on a low-orbit communication constellation

Abstract

The present invention proposes a method for maintaining a feeder link for a ground gateway station based on a low-orbit communication constellation, which belongs to the field of communication technology. Within the service area of ​​the ground gateway station, this method continuously monitors the operation of each orbital plane of the low-orbit communication constellation, dynamically assigns a fixed ground antenna to each orbital plane as much as possible, continuously establishes a feeder link with each orbital plane by alternating the use of the assigned ground antennas, and dynamically increases or decreases the number of ground antennas assigned to each orbital plane based on the real-time needs of each orbital plane. By scheduling and managing multiple ground antennas, it is ensured that each qualified communication satellite has a ground antenna that continuously points to and tracks the satellite from the time it enters the service area to the time it leaves the service area to continuously establish a feeder link, thereby ensuring the information delivery needs of the low-orbit satellite.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to a method for maintaining a ground gateway feeder link based on a low-orbit communication constellation. Background Art

[0002] A typical low-orbit communication constellation system primarily consists of user stations, low-orbit satellites, and ground gateways. LEO satellites are evenly distributed across multiple orbital planes, and multiple satellites within the same orbital plane are also typically evenly distributed. User stations relay information via low-orbit satellites to ground gateways, which then connect to external networks and ultimately communicate with them. The ground gateways can also forward information to another user station (via low-orbit satellite relays), ultimately enabling communication between the two user stations.

[0003] The satellite-to-ground link established between a ground gateway and a low-Earth orbit satellite is called a feeder link. Ground gateways are responsible for landing, processing, forwarding, and network management of information from the LEO constellation. Therefore, they must establish feeder links with as many LEO satellites as possible to ensure information landing. Due to the high-speed motion of LEO constellations, the number of LEO satellites visible to a given ground gateway changes frequently, requiring frequent adjustments to the feeder link, making it difficult to maintain the feeder link. Summary of the Invention

[0004] In light of this, the present invention proposes a method for maintaining a feeder link for a ground gateway station based on a low-orbit communication constellation. This method schedules and manages multiple ground antennas within the service area of ​​a ground gateway station to ensure that each eligible communication satellite has a ground antenna continuously pointing and tracking it from the time it enters the service area until it leaves the service area, thereby maintaining a continuous feeder link and ensuring the satellite's information delivery needs.

[0005] The technical solution adopted in the present invention is:

[0006] A method for maintaining a ground gateway feeder link based on a low-orbit communication constellation, characterized by comprising the following steps:

[0007] (1) Based on the service area of ​​the ground gateway station and the operation of the low-orbit satellite constellation, the number of ground antennas and supporting equipment required for the ground gateway station is determined through simulation analysis. All available ground antennas are regarded as an antenna pool and the status of all ground antennas is marked as "pending allocation";

[0008] (2) At any starting time T0, a corresponding ground antenna is allocated to each visible satellite in each visible orbital plane whose remaining service time is not less than a threshold value φ, and the corresponding ground antenna is controlled to rotate to the corresponding position to track the corresponding satellite and establish a feed link; in addition, a ground antenna is allocated to a satellite that will enter the service area within the subsequent time T0+τ and whose remaining service time is not less than a threshold value φ, and the ground antenna is rotated to the corresponding position to serve the corresponding satellite. All allocated ground antennas are marked as "allocated";

[0009] (3) Dynamically adjust the number of ground antennas assigned to each orbital plane, control the pointing direction of each ground antenna, maintain the feed link uninterrupted, and continuously monitor whether there is a satellite flying out of or about to fly into the service area after τ time; when a satellite flies out of the service area, if the ground antenna has not been assigned to the satellite, continue to operate; otherwise, if the ground antenna has been assigned to the satellite, execute step (4); when a satellite is about to fly into the service area after τ time, execute step (5);

[0010] (4) Determine whether the number of ground antennas serving the orbital plane needs to be reduced. If so, mark the ground antenna status corresponding to the satellite as "pending allocation" and recycle it to the antenna pool; otherwise, reallocate the ground antenna corresponding to the satellite to a subsequent satellite on the orbital plane and rotate it to the starting position of the subsequent satellite entering the service area, waiting to serve the subsequent satellite;

[0011] (5) Determine whether it is necessary to increase the number of ground antennas serving the orbital plane. If so, allocate an additional ground antenna to the orbital plane, mark the ground antenna status as "allocated", and rotate it to the starting position of the corresponding satellite entering the service area, waiting to serve the corresponding satellite; otherwise, no additional ground antenna is needed and the operation continues;

[0012] (6) If the service of the ground gateway station needs to be stopped, all ground antennas will be recovered to the antenna pool and the status of all recovered ground antennas will be marked as "pending allocation".

[0013] Furthermore, the value of τ is not less than the maximum time required for any ground antenna in the service area to rotate from any starting position to any specified position, thereby ensuring that any ground antenna can rotate to any specified position within the time τ; the value of φ satisfies the following conditions: the feeder link information landing function is only provided for satellites whose service time is not less than the threshold φ, and the feeder link information landing function is not provided for satellites whose service time is less than the threshold φ.

[0014] Furthermore, service time refers to the duration of time for a certain satellite to establish a feeder link within the service area to provide information landing, that is, the time from the satellite entering the service area to the time it leaves the service area; the remaining service time refers to the time from the time the corresponding ground antenna rotates to the designated position to the time the satellite leaves the service area.

[0015] Furthermore, the specific method of step (1) is:

[0016] Through simulation analysis from the initial time t to the end time t + τ, we determine the number M of satellites with visible service time at time t and a threshold value of φ, and the number N of newly visible satellites entering the service area with service time at least φ within the subsequent time τ. Therefore, the maximum number of satellites with visible service time at least φ within any time period τ within the ground gateway's service area is K = M + N. Therefore, the ground gateway is configured with K + 1 ground antennas and supporting equipment. Among them, M ground antennas are used to implement satellite information landing, N ground antennas are used to meet the satellite feed link switching function, and an additional ground antenna is configured to handle abnormal and unforeseen situations.

[0017] Furthermore, in step (2), at the start time, the remaining service time μ of the visible satellite is:

[0018] μ = max { Te – T0 – τ, 0}

[0019] Among them, Te is the time when the visible satellite leaves the service area of ​​the ground gateway station;

[0020] The remaining service time μ of the satellite that enters the service area at the subsequent time T0+τ is:

[0021] μ = max { Te – Ts + ( Ts – T0 ) – τ, 0}= max { Te – T0 – τ, 0}

[0022] Among them, Ts and Te are the times when the satellite enters and leaves the service area of ​​the ground gateway station respectively.

[0023] Furthermore, the specific method of step (4) is:

[0024] (401) Calculate the number of ground antennas required for the orbital plane at the current time t. Assume that the number of satellites with visible service time not less than the threshold φ at time t is m', including satellites that are about to fly out of the service area, and the number of satellites with service time not less than the threshold φ that will fly into the service area within the next τ time is n'. Then the number of ground antennas required for the orbital plane at the current time is k' = m' + n';

[0025] (402) Assuming that the number of antennas currently allocated to the orbital plane is k, if k = k', the ground antenna allocated to the outgoing satellite will be reallocated to the subsequent n'+1th satellite that enters the service area of ​​the orbital plane, and the ground antenna will be rotated to the starting position of the corresponding satellite entering the service area, waiting to serve the corresponding satellite; if k>k', it indicates that the number of antennas required for the orbital plane has decreased, and the ground antenna allocated to the outgoing satellite will be marked as "pending allocation" and recycled to the antenna pool.

[0026] Furthermore, the judgment method of step (5) is as follows: if a ground antenna has not been allocated for the incoming satellite, then one more ground antenna is allocated for the orbital plane, the antenna status is marked as "allocated", and it points to the starting position of the satellite entering the service area, waiting to serve the corresponding satellite; otherwise, it means that a ground antenna has been allocated, and there is no need to add another ground antenna, and the operation continues.

[0027] The beneficial effects of the present invention are:

[0028] 1. Within the service area of ​​a ground gateway, the present invention continuously monitors the operation of each orbital plane of a low-orbit communication constellation, dynamically assigns fixed ground antennas to each orbital plane as much as possible, continuously establishes a feeder link with each orbital plane by alternating the use of assigned ground antennas, and dynamically increases or decreases the number of ground antennas assigned to each orbital plane based on the real-time needs of each orbital plane.

[0029] 2. The present invention schedules and manages multiple ground antennas to ensure that each qualified communication satellite has a ground antenna that continuously points to and tracks the satellite from the time it enters the service area to the time it leaves the service area, so as to continuously establish a feed link and ensure the information landing needs of low-orbit satellites. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a flow chart of a method for maintaining a ground gateway feeder link based on a low-orbit communication constellation in an embodiment of the present invention;

[0031] Figure 2 1 is a schematic diagram of a ground gateway service area in an embodiment of the present invention;

[0032] Figure 3 is a schematic diagram of time T0 in an embodiment of the present invention;

[0033] Figure 4 is a schematic diagram of time T1 in an embodiment of the present invention;

[0034] Figure 5 Schematic diagram of the time periods T2 and T3 in an embodiment of the present invention. Implementation Method

[0035] The present invention will be further described below with reference to the accompanying drawings.

[0036] A method for maintaining a feeder link for a ground gateway station based on a low-orbit communication constellation. For a ground gateway station, within its service area, multiple ground antennas are scheduled and managed to ensure that for each qualified communication satellite, there is always a ground antenna that continuously points to and tracks the satellite from the time it enters the service area to the time it leaves the service area, thereby continuously establishing a feeder link and ensuring the satellite's information delivery needs.

[0037] like Figure 1 As shown, the method specifically includes the following steps:

[0038] (1) Based on the service area of ​​the ground gateway station and the operation of the low-orbit satellite constellation, the number of ground antennas (and supporting equipment) required for the ground gateway station is determined through simulation analysis. All available ground antennas are regarded as an antenna pool and the status of all ground antennas is marked as "pending allocation";

[0039] (2) At any starting time T0, a corresponding ground antenna is allocated to each visible satellite in each visible orbital plane whose remaining service time (after considering the antenna rotation time) is not less than the threshold φ, and the corresponding ground antenna is controlled to rotate to the corresponding position to track the corresponding satellite and establish a feed link; a ground antenna is allocated to a satellite that will enter the service area within the subsequent time T0+τ and whose remaining service time (after considering the antenna rotation time) is not less than the threshold φ, and the ground antenna is rotated to the corresponding position to serve the corresponding satellite. All allocated ground antennas are marked as "allocated";

[0040] Where τ is a time constant, whose value is not less than the maximum time required for any ground antenna in the service area to rotate from any starting position to any specified position, thereby ensuring that any ground antenna can rotate to any specified position within the time τ; φ is a time constant, the value of which needs to be considered in the actual project, that is, the feeder link information landing function is only provided for satellites whose service time (starting time is the remaining service time) is not less than the threshold φ, and the feeder link information landing function is not provided for satellites whose service time (starting time is the remaining service time) is less than the threshold φ;

[0041] The service time refers to the duration during which a feed link can be established within the service area for a certain satellite to provide information landing, that is, the time from the satellite entering the service area to the time it leaves the service area; the remaining service time at the starting time refers to the time from the time the corresponding ground antenna rotates to the designated position to the time the satellite leaves the service area.

[0042] (3) Taking into account the mobility of low-orbit satellites, dynamically adjust the number of ground antennas assigned to each orbital plane, control the pointing direction of each ground antenna, maintain the feed link uninterrupted, and continuously monitor whether there is a satellite flying out of or about to fly into the service area exactly after τ time. When a satellite flies out of the service area, if a ground antenna has not been assigned to the satellite, continue to operate; otherwise, it means that a ground antenna has been assigned to the satellite, and determine whether the number of ground antennas serving the orbital plane needs to be reduced, and execute step (4). When a satellite is about to fly into the service area exactly after τ time, determine whether the number of ground antennas serving the orbital plane needs to be increased, and execute step (5);

[0043] (4) When a satellite flies out of the service area and a ground antenna has been assigned to the satellite, determine whether the number of ground antennas serving the orbital plane needs to be reduced. If so, mark the state of the ground antenna corresponding to the satellite as "pending allocation" and recycle it to the antenna pool; otherwise, reallocate the ground antenna corresponding to the satellite to a subsequent satellite on the orbital plane and rotate it to the starting position of the subsequent satellite entering the service area, waiting to serve the subsequent satellite;

[0044] (5) When a satellite is about to enter the service area exactly after τ time, determine whether it is necessary to increase the number of ground antennas serving the orbital plane. If so, allocate an additional ground antenna to the orbital plane, mark the ground antenna status as "allocated", and rotate it to the starting position of the corresponding satellite entering the service area, waiting to serve the corresponding satellite; otherwise, no additional ground antenna is needed and the operation continues;

[0045] (6) If the service of the ground gateway station needs to be stopped, all ground antennas will be recovered to the antenna pool and the status of all recovered ground antennas will be marked as "pending allocation".

[0046] In step (1), through simulation analysis over a period of time, the maximum number of satellites (assuming it is K) with a service time not less than a threshold value φ that can be seen within any time period τ within the service area of ​​the ground gateway is obtained. The symbol t represents the initial time of the period, and the end time is t+τ. M and N represent the number of satellites with a service time not less than a threshold value φ at time t and the number of satellites that have entered the service area and whose service time is not less than a threshold value φ within the subsequent time τ, respectively. It is necessary to build M ground antennas to realize the landing of satellite information, and to build N additional ground antennas to meet the feed link switching function for the satellite. In addition, one more ground antenna is configured to handle abnormal and unforeseen situations. Therefore, the ground gateway is configured with K+1 ground antennas and supporting equipment.

[0047] In step (2), at the start time, the remaining service time of a visible satellite (after considering the antenna rotation time) μ is:

[0048] μ = max { Te – T0 – τ, 0}

[0049] Where Te is the time when the satellite leaves the service area of ​​the ground gateway;

[0050] The remaining service time μ of a satellite that enters the service area within the subsequent time T0+τ (after considering the antenna rotation time) is:

[0051] μ = max { Te – Ts + ( Ts – T0 ) – τ, 0}= max { Te – T0 – τ, 0}

[0052] Ts and Te are the times when the satellite enters and leaves the service area of ​​the ground gateway, respectively.

[0053] Step (4) specifically includes the following steps:

[0054] (401) Calculate the number of ground antennas required for the orbital plane at the current time (labeled as t). Assume that the number of satellites with visible service time not less than the threshold φ at time t is m' (including the satellite that is about to fly out of the service area), and the number of satellites with service time not less than the threshold φ that will fly into the service area within the next τ time is n'. Then the number of ground antennas required for the orbital plane at the current time is k' = m' + n';

[0055] (402) Assuming that the number of antennas currently allocated to the orbital plane is k, if k = k', the ground antenna allocated to the outgoing satellite will be reallocated to the subsequent n'+1th satellite that enters the service area of ​​the orbital plane, and the ground antenna will be rotated to the starting position of the corresponding satellite entering the service area, waiting to serve the corresponding satellite; if k>k', it indicates that the number of antennas required for the orbital plane has decreased, and the ground antenna allocated to the outgoing satellite will be marked as "pending allocation" and recycled to the antenna pool.

[0056] The judgment condition of step (5) is: if a ground antenna has not been assigned to the satellite, then one more ground antenna is assigned to the orbital plane, the antenna status is marked as "assigned", and it points to the starting position of the satellite entering the service area, waiting to serve the corresponding satellite; otherwise, it means that a ground antenna has been assigned, and there is no need to add another ground antenna, and the operation continues.

[0057] This method tries to assign a fixed ground antenna to each orbital plane, and then dynamically increase or decrease the number of antennas according to the needs of the orbital plane, without frequently changing different ground antennas for the same orbital plane.

[0058] The following is a specific explanation using a certain orbital plane of a low-orbit communication constellation as an example.

[0059] like Figure 2 As shown, assume that a ground gateway station projects the service area of ​​a low-orbiting constellation onto the Earth as a unit circle with a radius of R. Multiple satellites are evenly distributed within each orbital plane of the low-orbiting constellation, and the inter-satellite separation distance of their projections onto the Earth is exactly R. Assume that the velocity of the projections of the low-orbiting satellites onto the Earth is v, and the threshold φ is set to R / (2v). The value of τ should be no less than the maximum time required for any ground antenna in the service area to rotate from any starting position to any specified position, here set to R / v. That is, the orbital projection distance of each low-orbiting satellite within τ is exactly R. (This assumption is for better illustration of the working principle of this patent; in practice, τ can be set to the maximum time required for any ground antenna in the service area to rotate from any starting position to any pointing position.) Figure 2 Here, L4 is the diameter of the unit circle and has a length of 2R. L2 and L5 are each R in length. L0 and L1 are less than R and greater than R / 2, L3 is greater than R and less than 2R, and L6 is less than R and greater than R / 2. Since the Earth rotates from west to east, the projection of this orbital plane onto Earth also moves slowly from west to east.

[0060] At time T0 (such as Figure 3 As shown in the figure), the ground gateway station starts to operate and the ground antenna needs to be initially allocated. It is assumed that the projection of the orbit to the ground is located at L0, and S i1 Just entered the service area for a short time, due to S i1 The remaining service time is less than the threshold φ, so it is not S i1 Assign ground antennas; and the satellite S that can fly into the service area within τ time (i1+1)%X The remaining service time is greater than the threshold φ, so it should be satellite S (i1+1)%X Assign ground antennas. Then, continue to monitor whether there is a satellite flying out or about to fly into the service area just after τ time. After a period of time, assuming it is time T0', the orbital projection on the ground is at L0', and S i1 As it is about to fly out of the service area, it triggers the event of determining whether to reduce the number of ground antennas serving the orbital plane. i1 The ground antenna is assigned so the algorithm continues to run.

[0061] After a period of time, assuming it is time T1 (such as Figure 4 As shown), the projection of the track facing the earth is located at L1, and S (i1+2)%X It will enter the service area just after τ time, because there is no satellite S (i1+2)%X Assign ground antenna, then satellite S (i1+2)%X Allocate a ground antenna and rotate the ground antenna to the satellite S (i1+2)%XEnter the starting position of the service area. After a period of time, assuming it is time T1', the projection of the track facing the ground is at L1', and S (i1+1)%X It is about to fly out of the service area, triggering the event of whether to reduce the number of ground antennas serving the orbital plane. (i1+1)%X To allocate ground antennas, perform the following steps: The number of visible satellites at the current moment is m'=1 (i.e. S (i1+1)%X ), the number of satellites that will fly into the service area in the subsequent τ time is n'=1 (i.e. S (i1+2)%X ), then the number of antennas required for this orbital plane at the current moment is k'=1+1=2; the number of ground antennas currently allocated to this orbital plane is k=2 (S (i1+1)%X and S (i1+2)%X antennas have been assigned), that is, k=k', then it will be assigned to satellite S (i1+1)%X The ground antenna is reallocated to the subsequent n'+1=2 satellites that fly into the service area, that is, S (i1+3)%X and rotate the ground antenna to the satellite S (i1+3)%X Enter the starting position of the service area. After a period of time, assuming it is time T1'', the projection of the track facing the ground is at L1'', and S (i1+3) / X It will enter the service area just after τ time; at this time, it triggers the event of whether to increase the number of ground antennas serving the orbital plane. Since the current S (i1+3) / X If a ground antenna is assigned, no additional ground antenna is needed and the algorithm continues to run. At time T1 and a period of time thereafter (before time T2), the ground gateway continues to use two ground antennas to alternately realize the landing of satellite information on the orbital plane.

[0062] At time T2 (e.g. Figure 5 As shown in Figure 2), assuming that the projection of the orbit facing the Earth is located at L3 (the first time it reaches or crosses L2), and S (i2+2) / X It will enter the service area just after τ time. At this time, it triggers the event of whether to increase the number of ground antennas serving the orbital plane. Since only two ground antennas are currently allocated to the orbital plane, serving S i2 and S (i2+1)%X , did not give S (i2+2)%X Assign a ground antenna, so assign one more ground antenna to the orbital plane, mark the antenna status as "assigned", and rotate the ground antenna to the satellite S (i2+2)%X The starting position for subsequent entry into the service area. At time T2 and a period of time thereafter (before time T3), the ground gateway uses three ground antennas to alternately realize the landing of satellite information on the orbital plane.

[0063] At time T3, it is assumed that the projection of the orbit facing the earth is located at L6 (reaching or crossing L5 for the first time), and S i3 Just about to fly out of the service area, triggering the event of whether to reduce the number of ground antennas serving the orbital plane. The number of visible satellites at the current moment is m'=1 (i.e. S i3 ), the number of satellites that will fly into the service area in the subsequent τ time is n'=1 (i.e. S (i3+1)%X ), then the number of ground antennas required for this orbital plane at the current moment is k'=1+1=2; the number of ground antennas currently allocated to this orbital plane is k=3 (S i3 、S (i3+1)%X 、S (i3+2)%X antennas have been allocated), that is, k>k', which means that the number of ground antennas required for this orbital plane is reduced, and the number of ground antennas allocated to satellite S i3 The ground antenna status is marked as "pending allocation" and returned to the antenna pool. At time T3 and for a period of time thereafter (until the antenna is reduced again), the ground gateway uses two ground antennas to alternately land satellite information on the orbital plane.

[0064] If the service of the ground gateway station needs to be stopped, all ground antennas will be recovered to the antenna pool and the status of all recovered ground antennas will be marked as "pending allocation".

[0065] In summary, within the service area of ​​a ground gateway, this invention continuously monitors the operation of each orbital plane of the low-orbit communication constellation, dynamically assigning fixed ground antennas to each orbital plane as much as possible. This system then alternates between the use of assigned ground antennas to continuously establish a feeder link with each orbital plane, dynamically increasing or decreasing the number of ground antennas assigned to each orbital plane based on the real-time needs of each orbital plane. By scheduling and managing multiple ground antennas, this system ensures that each eligible communication satellite has a ground antenna continuously pointing and tracking it to establish a feeder link from the time it enters the service area until it leaves, thus ensuring that the information needs of the low-orbit satellite are met.

Claims

1. A method for maintaining a ground gateway feeder link based on a low-orbit communication constellation, characterized in that: The following steps are involved: (1) Based on the service area of ​​the ground gateway station and the operation of the low-orbit satellite constellation, the number of ground antennas and supporting equipment required for the ground gateway station is determined through simulation analysis. All available ground antennas are regarded as an antenna pool and the status of all ground antennas is marked as "pending allocation"; (2) At any starting time T0, a corresponding ground antenna is assigned to each visible satellite in each visible orbital plane whose remaining service time is not less than a threshold value φ, and the corresponding ground antenna is controlled to rotate to the corresponding position to track the corresponding satellite and establish a feed link; In addition, ground antennas are allocated to satellites that will enter the service area within the subsequent time T0+τ and whose remaining service time is no less than a threshold φ. The ground antennas are rotated to the corresponding positions to serve the corresponding satellites, and all allocated ground antennas are marked as "allocated". The value of τ is no less than the maximum time required for any ground antenna in the service area to rotate from any starting position to any specified position. The value of φ satisfies the following conditions: the feeder link information landing function is only provided for satellites with a service time no less than the threshold φ, and is not provided for satellites with a service time less than the threshold φ. Service time refers to the duration of time that a feeder link can be established within the service area for a certain satellite to provide information landing, that is, the time from the satellite entering the service area to the time it leaves the service area; The remaining service time refers to the time from the time the corresponding ground antenna rotates to the designated position to the time the satellite leaves the service area; (3) Dynamically adjust the number of ground antennas assigned to each orbital plane, control the pointing direction of each ground antenna, maintain the feed link uninterrupted, and continuously monitor whether there is a satellite flying out of or about to fly into the service area after τ time; when a satellite flies out of the service area, if the ground antenna has not been assigned to the satellite, continue to operate; otherwise, if the ground antenna has been assigned to the satellite, execute step (4); when a satellite is about to fly into the service area after τ time, execute step (5); (4) Determine whether the number of ground antennas serving the orbital plane needs to be reduced. If so, mark the ground antenna status corresponding to the satellite as "pending allocation" and recycle it to the antenna pool; otherwise, reallocate the ground antenna corresponding to the satellite to a subsequent satellite on the orbital plane and rotate it to the starting position of the subsequent satellite entering the service area, waiting to serve the subsequent satellite; (5) Determine whether it is necessary to increase the number of ground antennas serving the orbital plane. If so, allocate an additional ground antenna to the orbital plane, mark the ground antenna status as "allocated", and rotate it to the starting position of the corresponding satellite entering the service area, waiting to serve the corresponding satellite; otherwise, no additional ground antenna is needed and the operation continues; (6) If the service of the ground gateway station needs to be stopped, all ground antennas will be recovered to the antenna pool and the status of all recovered ground antennas will be marked as "pending allocation".

2. The method for maintaining a ground gateway feeder link based on a low-orbit communication constellation according to claim 1, characterized in that: The specific method of step (1) is: Through simulation analysis from the initial time t to the end time t+τ, we can obtain the number of satellites M with visible service time not less than the threshold φ at time t, and the number of satellites N newly entering the service area with service time not less than the threshold φ that can be seen within the subsequent time τ. Therefore, the maximum number of satellites with service time not less than the threshold φ that can be seen within any time period τ within the ground gateway service area is K=M+N; Therefore, the ground gateway is configured with K+1 ground antennas and supporting equipment, among which M ground antennas are used to realize the landing of satellite information, N ground antennas are used to meet the feed link switching function of the satellite, and the additional ground antenna is used to handle abnormal and unforeseen situations.

3. The method for maintaining a ground gateway feeder link based on a low-orbit communication constellation according to claim 1, wherein: In step (2), at the start time, the remaining service time μ of the visible satellite is: μ = max { Te – T0 – τ, 0} Among them, Te is the time when the visible satellite leaves the service area of ​​the ground gateway station; The remaining service time μ of the satellite that enters the service area at the subsequent time T0+τ is: μ = max { Te – Ts + ( Ts – T0 ) – τ, 0}= max { Te – T0 – τ, 0} Among them, Ts and Te are the times when the satellite enters and leaves the service area of ​​the ground gateway station respectively.

4. The method for maintaining a ground gateway feeder link based on a low-orbit communication constellation according to claim 1, wherein: The specific method of step (4) is: (401) Calculate the number of ground antennas required for the orbital plane at the current time t. Assume that the number of satellites with visible service time not less than the threshold φ at time t is m', including satellites that are about to fly out of the service area, and the number of satellites with service time not less than the threshold φ that will fly into the service area within the next τ time is n'. Then the number of ground antennas required for the orbital plane at the current time is k' = m' + n'; (402) Assuming that the number of antennas currently allocated to the orbital plane is k, if k = k', the ground antenna allocated to the outgoing satellite will be reallocated to the subsequent n'+1th satellite that enters the service area of ​​the orbital plane, and the ground antenna will be rotated to the starting position of the corresponding satellite entering the service area, waiting to serve the corresponding satellite; if k > k', it indicates that the number of antennas required for the orbital plane has decreased, and the ground antenna allocated to the outgoing satellite will be marked as "pending allocation" and recycled to the antenna pool.

5. The method for maintaining a ground gateway feeder link based on a low-orbit communication constellation according to claim 1, wherein: The judgment method of step (5) is as follows: if there is no ground antenna assigned to the incoming satellite, then one more ground antenna is assigned to the orbital plane, the antenna status is marked as "assigned", and it points to the starting position of the satellite entering the service area, waiting to serve the corresponding satellite; otherwise, it means that the ground antenna has been assigned, and there is no need to add another ground antenna, and the operation continues.

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