A User Grouping and Beam Hopping Scheduling Method for Low Earth Orbit Satellite Systems

Abstract

This invention proposes a user grouping and beam hopping scheduling method for low-Earth orbit (LEO) satellite systems, applicable to the field of communication technology. Within a beam hopping scheduling cycle, LEO satellite ground users are dynamically grouped and their positions dynamically determined according to their geographical location and the coverage area of ​​the satellite beam hopping beam at that location, thereby reducing the number of positions. Multiple beam hopping beams of the satellite are scheduled, and each beam hopping beam accesses each of the multiple positions it serves only once within a beam hopping scheduling cycle, and stays there for as long as possible to meet the real-time online and service transmission needs of multiple users under that position, significantly reducing the number of beam hopping cycles.

Description

Technical Field

[0001] This invention relates to a user grouping and beam hopping scheduling method for low-Earth orbit satellite systems, applicable to the field of communication technology. Background Technology

[0002] Low Earth orbit (LEO) satellite users are characterized by random location distribution, varying service demands, and small-scale clustering of some users. Most current LEO satellite communication systems utilize phased array antennas to create multiple hopping beams to the ground, pre-planning the ground area into multiple wavelengths. These beams periodically hop frequently within each wavelength range to support information transmission for ground users within the coverage area. This frequent hopping increases the satellite's overhead and complexity. Summary of the Invention

[0003] The technical problem to be solved by this invention is to design a user grouping and beam hopping scheduling method for low-Earth orbit satellite systems. This invention dynamically groups low-Earth orbit satellite users according to their geographical location and the coverage area of ​​the satellite beam hopping in that geographical location, and dynamically determines the beam positions to reduce the number of beam positions. Within one beam hopping cycle, multiple beam hopping of the satellite are scheduled, and the beams are directed to each user group in a time-division manner. While ensuring the real-time online needs and service transmission needs of each user group, the number of beam hopping times is minimized.

[0004] The technical solution adopted in this invention is as follows:

[0005] A method for user grouping and beam hopping scheduling in a low-Earth orbit satellite system specifically includes the following steps:

[0006] (1) Within a hopping beam scheduling cycle, determine the number of hopping beam time slots required by each user within the low-orbit satellite coverage area;

[0007] (2) Determine the number of time slots allocated to each user based on the number of hopping beam time slots required by each user and the satellite hopping beam time slot resources;

[0008] (3) Based on the geographical location of each user within the low-orbit satellite coverage area, a wave position Bi is determined for each user Ui, and a total of N wave positions are initially determined; where 1≤i≤N, and N is the number of users;

[0009] (4) For each user Ui, based on the relative position of the wave position and the low-orbit satellite, determine the coverage area of ​​the satellite hopping beam center pointing to the corresponding wave position center, add all users included in the coverage area to group Pi, and finally obtain the initial group set P = {P1, P2, ..., PN}, where each group Pi is represented by user Ui;

[0010] (5) If the number of elements in set P is greater than 0, then execute step (6); otherwise execute step (7).

[0011] (6) Select the group with the most users in set P. If there are multiple groups with the same number of users, select the group with the largest sum of time slots allocated to all users in the group with the same number of users. Add the selected group to set Q, and for each user in the selected group, delete the group represented by these users in set P. Execute step (5).

[0012] (7) For each group in set Q, determine the number of time slots allocated to each group. The number of time slots allocated to each group is the sum of the number of time slots allocated to each user in the group.

[0013] (8) Allocate each time slot of each hopping beam sequentially to each group in set Q, and perform hopping beam scheduling within the period according to the allocation result; and for each group, adjust the center of the allocated hopping beam to point to the wave position center of the corresponding group, and stay for the corresponding number of time slots.

[0014] Furthermore, the specific content of step (1) is as follows: if the user has no service transmission requirements, the number of hop beam time slots required by the user is marked as 1; if the user has service transmission requirements, the number of hop beam time slots required by the user is marked as ceil((R / R0)*S), where R and R0 are the user's service rate requirements and the communication rate under the single beam service condition calculated according to the user's channel environment, S is the total number of time slots owned by a single hop beam in one scheduling period, and ceil((R / R0)*S) is (R / R0)*S rounded up to the nearest integer.

[0015] Furthermore, the specific content of step (2) is as follows: if the sum of the number of time slots required by all users is not greater than the sum of the number of time slots owned by the multiple hopping beams of the satellite, i.e., M*S, then the number of time slots required for each user is determined; otherwise, the number of time slots allocated to each user is reduced proportionally, but each user is ensured to be allocated at least 1 time slot; where M is the number of hopping beams owned by the satellite, and S is the total number of time slots owned by a single hopping beam in one scheduling cycle.

[0016] Furthermore, the specific content of step (3) is as follows: for each user within the coverage area of ​​the low-orbit satellite, if the angle θ formed between the satellite hopping beam center and the satellite center when the satellite hopping beam center points to the user's geographical location is not greater than the maximum scanning angle threshold θmax of the satellite hopping beam, then the user's geographical location is the corresponding beam center position; otherwise, the beam center position is adjusted on the line connecting the user's geographical location and the nadir point of the low-orbit satellite's projection onto the ground, so that the angle formed between the hopping beam and the low-orbit satellite center when the hopping beam points to the beam center position is θmax.

[0017] Furthermore, the low-orbit satellite contains M hopping beams configured with different frequencies, with multiple hopping beams pointing simultaneously to a single ground wave position or pointing to different ground wave positions respectively.

[0018] Furthermore, the hopping beam angle of low-Earth orbit satellites is fixed. The larger the angle between the hopping beam and the center of the satellite, the greater the coverage area on the ground.

[0019] Furthermore, for the multiple wavelengths served by each hop beam, it only accesses each wavelength only once within a scheduling cycle and stays for a set time to meet the service transmission needs of multiple users under the wavelength.

[0020] The beneficial effects of this invention are as follows:

[0021] Within a single beam hopping scheduling cycle, low-Earth orbit satellite users are dynamically grouped and their positions are dynamically determined according to their geographical location and the coverage area of ​​the satellite beam hopping beam in that geographical location to reduce the number of positions. Furthermore, each beam hopping beam accesses each position it serves only once within a scheduling cycle, significantly reducing the number of beam hopping cycles. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the method flow of the present invention;

[0023] Figure 2 This is a schematic diagram of a low-orbit satellite communication system in a specific implementation of the present invention. Detailed Implementation

[0024] The invention will now be further described with reference to the accompanying drawings.

[0025] like Figure 2 As shown, the satellite communication system applicable to this method consists of low-Earth orbit (LEO) satellites and ground users. LEO satellites achieve full control coverage within their coverage area through a wide-area control beam (wide beam), and provide service coverage to users by hopping between several service hopping beams (spot beams) as needed within the coverage area. Ground users request service hopping beam time slots from the LEO satellites through the wide-area control beam. The LEO satellites group these users according to their geographical location and service transmission needs, determine the hopping positions, and the dwell time of each hopping beam on each position, ensuring the real-time online and service transmission needs of each user.

[0026] Flowchart as follows Figure 1 As shown, the specific steps include:

[0027] (1) Within a hopping beam scheduling cycle, each user within the LEO satellite coverage area applies to the LEO satellite for the required number of hopping beam time slots through the wide area control beam. If the user has no service transmission needs, the number of time slots applied for is 1 to ensure that the user remains online in real time within each scheduling cycle; if the user has service transmission needs, the number of time slots applied for is ceil((R / R0)*S), where R and R0 are the user's service rate requirements and the communication rate calculated according to the user's channel environment under the single beam service condition, S is the total number of time slots available for a single hopping beam in one scheduling cycle, and ceil((R / R0)*S) is (R / R0)*S rounded up to the nearest integer;

[0028] (2) The low-Earth orbit (LEO) satellite determines the number of time slots allocated to each user based on the number of time slots required by each user and the satellite's hopping beam time slot resources. If the sum of the number of time slots required by all users is not greater than the sum of the number of time slots owned by the satellite's multiple hopping beams (i.e., M*S), then the required number of time slots is allocated to each user; otherwise, the number of time slots allocated to each user is reduced proportionally, but each user is ensured to be allocated at least one time slot, where M is the number of hopping beams owned by the satellite. The M hopping beams contained in the LEO satellite are configured with different frequencies, and multiple hopping beams can point to the same ground wave position simultaneously, or they can point to different ground wave positions respectively.

[0029] (3) The low-Earth orbit (LEO) satellite determines a band position Bi for each user Ui (1≤i≤N) based on the physical location of each user within its coverage area. For each user within the LEO satellite's coverage area, if the angle θ formed between the satellite's hopping beam center and the satellite center when the satellite's hopping beam center points to the user's geographical location is not greater than the maximum hopping beam scanning angle threshold θmax, then the user's geographical location is the corresponding band position center position; otherwise, the band position center position is adjusted on the line connecting the user's geographical location and the nadir point of the LEO satellite's Earth projection, so that the angle formed between the hopping beam and the satellite center when the hopping beam points to the band position center position is θmax. Initially, a total of N band positions are determined, where N is the number of users;

[0030] (4) For each user Ui, the low-orbit satellite determines the coverage area from the satellite hopping beam center to the center of the beam center based on the relative position of the user's corresponding beam position and the low-orbit satellite. All users included in the coverage area are added to group Pi, and finally the initial group set P = {P1, P2, ..., PN} is obtained, where each group Pi is represented by user Ui.

[0031] (5) If the number of elements in set P is greater than 0, then execute step (6); otherwise execute step (7).

[0032] (6) Select the group with the most users in set P. If there are multiple groups with the same number of users, then select the group with the largest sum of time slots allocated to all users in the group with the same number of users. Add the group to set Q. For each user in the group, delete the group represented by these users in set P and execute step (5).

[0033] (7) For each group in the low-orbit satellite pair set Q, determine the number of time slots to be allocated to that group. The number of time slots allocated to that group is the sum of the number of time slots allocated to each user in that group.

[0034] (8) The low-Earth orbit satellite sequentially and continuously allocates each time slot of each hopping beam to each group in set Q, and broadcasts the allocation results in the wide-area control beam to notify each user. After the notification is completed, the low-Earth orbit satellite performs hopping beam scheduling for that period according to the allocation results; for each group, the center of the allocated hopping beam is adjusted to point to the wave position center of the corresponding group, and stays in the corresponding number of time slots.

[0035] In summary, this invention proposes a user grouping and beam hopping scheduling method for low-Earth orbit (LEO) satellite systems. Within a beam hopping scheduling cycle, LEO satellite ground users are dynamically grouped and their positions are dynamically determined according to their geographical location and the coverage area of ​​the satellite beam hopping beam at that location, thereby reducing the number of positions. Multiple beam hopping beams of the satellite are scheduled, and each beam hopping beam accesses each of the multiple positions it serves only once within a beam hopping scheduling cycle, and stays there for as long as possible to meet the real-time online and service transmission needs of multiple users under that position, significantly reducing the number of beam hopping cycles.

Claims

1. A method for user grouping and beam hopping scheduling in a low-Earth orbit satellite system, characterized in that, Specifically, the following steps are included: (1) Within a hopping beam scheduling cycle, determine the number of hopping beam time slots required by each user within the low-orbit satellite coverage area; (2) Determine the number of time slots allocated to each user based on the number of hopping beam time slots required by each user and the satellite hopping beam time slot resources; (3) Based on the geographical location of each user within the low-orbit satellite coverage area, for each user Ui Determine a wave position Bi Initially determined N One wave position; among them. 1 ≤ i ≤ N , N For the number of users; (4) Dynamically group low-Earth orbit satellite users according to their geographical location and the coverage area of ​​the satellite hop beam in that geographical location. The specific process is as follows: for each user Ui Based on the relative position of the wavefront and the low-Earth orbit satellite, the coverage area from the satellite's hop beam center to the corresponding wavefront center is determined, and all users within the coverage area are added to a group. Pi Finally, the initial group set is obtained. P = {P1, P2, ..., PN} Each group Pi With users Ui For example, the low-Earth orbit satellite has a fixed beam hopping angle; the larger the angle between the beam hopping and the satellite center, the larger the coverage area on the ground. (5) If set P If the number of elements contained is greater than 0, then proceed to step (6); otherwise, proceed to step (7). (6) Selecting a set P The group with the largest number of users is selected. If multiple groups have the same number of users, the group with the largest sum of allocated time slots for all users in that group is selected and added to the set. Q And for each user in the selected group, in the set P Delete the group represented by these users and proceed to step (5); (7) For sets Q For each group in the data, determine the number of time slots allocated to each group. The number of time slots allocated to a group is the sum of the number of time slots allocated to each user in the group. (8) Allocate the time slots of each hopping beam sequentially and continuously to the set. Q Each group in the process, each hop beam for the multiple wavelengths it serves, accesses each wavelength only once within a scheduling cycle and stays for a set time to meet the service transmission needs of multiple users under the wavelength. (9) Perform intra-cycle hopping beam scheduling according to the allocation results; and for each group, adjust the allocated hopping beam center to point to the corresponding group's beam position center, and stay for the corresponding number of time slots.

2. The method for user grouping and beam hopping scheduling in a low-Earth orbit satellite system according to claim 1, characterized in that, Step (1) specifically involves: if the user has no service transmission requirements, then mark the number of hop beam timeslots required by the user as 1; if the user has service transmission requirements, then mark the number of hop beam timeslots required by the user as... ceil((R / R 0 )*S) ,in R and R 0 This refers to the user's service rate requirements and the communication rate calculated based on the user's channel environment under single-beam service conditions. S This refers to the total number of time slots a single hopping beam has within one scheduling cycle. ceil((R / R 0 )*S) for (R / R) 0 )*S Round up to the nearest integer.

3. The method for user grouping and beam hopping scheduling in a low-Earth orbit satellite system according to claim 1, characterized in that, Step (2) specifically states: If the sum of the number of time slots required by all users is not greater than the sum of the number of time slots possessed by the multiple hopping beams of the satellite, that is... M*S If the number of time slots allocated to each user is determined, then the required number of time slots is allocated to each user; otherwise, the number of time slots allocated to each user is reduced proportionally, but each user is ensured to be allocated at least one time slot. M The number of hopping beams a satellite possesses. S The total number of time slots a single hop beam has within a scheduling cycle.

4. The method for user grouping and beam hopping scheduling in a low-Earth orbit satellite system according to claim 1, characterized in that, Step (3) specifically involves determining the angle between the satellite's hopping beam center and the satellite center when the satellite's beam hopping center points to the user's geographical location. θ Not greater than the maximum scanning angle threshold of satellite beam hopping θmax If the user's geographical location is correct, then the corresponding wavefront center position is the user's location; otherwise, adjust the wavefront center position on the line connecting the user's geographical location and the nadir point of the low-Earth orbit satellite's projection onto the Earth, so that the angle formed between the hopping beam pointing to the wavefront center position and the center of the low-Earth orbit satellite is [value missing]. θmax .

5. The method for user grouping and beam hopping scheduling in a low-Earth orbit satellite system according to claim 3, characterized in that, The low-Earth orbit satellite contains M hopping beams, each configured with a different frequency. Multiple hopping beams can point to a single ground wave position simultaneously or to different ground wave positions.

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