A multi-dimensional satellite beam switching method and device based on position prediction

Abstract

The present invention discloses a multi-dimensional satellite beam switching method based on position prediction. The method is: first, the gateway station receives the switching index sent by the terminal and stores the index sent by the terminal; then the gateway station determines whether the terminal is already in the beam switching critical area, calculates the distance between the current position of the terminal and the center points of each adjacent beam, and the distance between the current position and the center point of the current beam, and determines whether there is a smaller distance. If so, beam switching is performed; otherwise, the position of the terminal is calculated at the next report. If the predicted position is still within the coverage of the current beam and is not located in the switching critical area, no switching is required; otherwise, the gateway station calculates the distance between the predicted terminal position and the center points of each beam, and determines whether there is a smaller distance. If so, the time when the terminal enters the beam is calculated, and the time when the terminal is notified to switch is not required; otherwise, no switching is required. The present invention solves the problem of beam switching during terminal movement and improves the accuracy of beam switching.

Description

Technical Field

[0001] The present invention relates to the field of satellite communication technology, and in particular to a multi-dimensional satellite beam switching method based on position prediction. Background Art

[0002] In satellite communication systems, due to the mobility of satellites and terminals, when both satellites and terminals are in motion, the terminal may move out of the current beam and cross to other adjacent beams. In order to maintain the communication quality of the terminal, it is necessary to switch between beams or satellites when the terminal crosses the beam boundary. Switching is an important design part of satellite mobile communication systems. Generally, different satellite communication system scenarios select different switching algorithms. The quality of the switching algorithm and the correctness of the switching decision strategy directly affect the communication performance of the system. According to the different scenarios of the satellite communication system, the location of the terminal before and after the switching, whether the terminal is served by the same gateway, whether the terminal is served by the same satellite, and whether the terminal is covered by the same beam, there are generally four different switching methods: the first is switching between different beams of the same satellite; the second is switching between different satellites of the same gateway; the third is switching between the same satellite of different gateways; and the fourth is switching between different satellites of different gateways. Due to the relatively high-speed movement between satellites and mobile terminals, terminal users need to switch between satellites continuously to obtain uninterrupted communication services. The performance of the switching algorithm will directly affect the user's call quality.

[0003] Switching technology ensures service continuity, but it also brings greater overhead to the entire system. In satellite mobile communication systems with limited wireless resources, unnecessary switching will cause waste of system resources due to the expensive satellite bandwidth resources and the increasing number of connection requesting user terminals. Therefore, how to select the appropriate switching strategy according to the usage scenario is an urgent problem to be solved.

[0004] Invention patent CN202011124839.8 discloses a satellite beam switching method and system based on multi-dimensionality, and performs satellite beam switching based on multi-dimensional indicators. The technical solution adopted by the invention is: monitoring the current satellite terminal's to-be-switched indicator information, which includes the original beam receiving signal strength at the current moment, the receiving signal strength of each adjacent beam, the channel quality, the available resources of each adjacent beam, and the position coordinates of each adjacent beam; obtaining the maximum value of the switching threshold according to the to-be-switched indicator information, and performing beam switching on the satellite when the current gateway determines that the maximum value of the switching threshold meets the preset conditions. The invention adopts a decision algorithm based on a fuzzy logic system. The input parameters of the fuzzy logic system are multi-dimensional, and the position coordinates between the original beam and the adjacent beam are obtained by a time-sharing active measurement method. The output parameter of the fuzzy logic system is not a single value. Multiple switching threshold values ​​can be obtained by measuring the relevant parameters of multiple adjacent beams, and the maximum value of the switching threshold is obtained therefrom. The maximum value is used as the judgment basis for switching between different beams, so that the target beam that needs to be switched can be accurately obtained. However, the invention still has the following problems: (1) The terminal only obtains the received signal strength of the original beam, the received signal strength of each adjacent beam, the channel quality, the available resources of each adjacent beam, and the position coordinates of each adjacent beam at the current moment, but does not obtain the terminal's own position information, heading, and speed; (2) The movement trajectory of the terminal is not a fixed straight line, but is likely to be a curve, and the beam switching is not selected from the perspective of movement; (3) The computing power of the terminal is relatively weak, and it takes a long time to calculate the switching threshold, but the terminal may move very fast. In this case, when the gateway receives the switching threshold sent by the terminal, there is a large error from the situation when the terminal is sampled, which affects the real-time and accuracy of the beam switching. Summary of the invention

[0005] The purpose of the present invention is to provide a multi-dimensional satellite beam switching method based on position prediction to solve the problem of beam switching during terminal movement, reduce the error caused by terminal calculation time, and improve the accuracy of beam switching.

[0006] The technical solution to achieve the purpose of the present invention is: a multi-dimensional satellite beam switching method based on position prediction, comprising the following steps:

[0007] Step 1: The gateway receives the switching indicator sent by the terminal and stores the indicator sent by the terminal;

[0008] Step 2: The gateway determines whether the signal strength of the current beam is lower than the switching threshold, or whether the terminal is already in the current beam switching critical area: if yes, proceed to step 3; otherwise, notify the terminal that no switching is required;

[0009] Step 3: The gateway calculates the distance between the terminal's current position and the center points of each adjacent beam, and the distance between the current position and the center point of the current beam, and determines whether there is a beam with a smaller distance, and the signal strength of the beam with a smaller distance is higher than the signal strength of the current beam. If yes, the terminal is notified to switch, and the target beam is the beam with the smallest distance among the beams with a smaller distance, and the switching timing is immediate; otherwise, the process goes to step 4;

[0010] Step 4: The gateway calculates the predicted position of the terminal at the next reporting time based on the current heading, speed, and historical trajectory: If the predicted position is still within the coverage of the current beam and is not within the critical area of ​​the current beam switching, the terminal is notified that no switching is required; otherwise, it proceeds to step 5;

[0011] Step 5: The gateway calculates the distance between the terminal's predicted position and the center point of each beam, and determines whether the distance between the predicted position and the center point of the current beam is the minimum. If yes, the terminal is notified that there is no need to switch. Otherwise, the time for the terminal to enter the beam with the minimum distance is calculated based on the speed and heading, and the terminal is notified to switch to the beam with the minimum distance.

[0012] A multi-dimensional satellite beam switching device based on position prediction, comprising:

[0013] The gateway station receiving storage module is used to receive the switching indicator sent by the terminal and store the indicator sent by the terminal;

[0014] The first judgment module of the gateway station is used to judge whether the signal strength of the current beam is lower than the switching threshold, or whether the terminal is already in the current beam switching critical area: if yes, enter the second judgment module of the gateway station; otherwise, notify the terminal that no switching is required;

[0015] The second judgment module of the gateway station is used to calculate the distance between the current position of the terminal and the center point of each adjacent beam, and the distance between the current position and the center point of the current beam, and judge whether there is a beam with a smaller distance, and the signal strength of the beam with a smaller distance is higher than the signal strength of the current beam: if yes, the terminal is notified to switch, the target beam is the beam with the smallest distance in the beam with a smaller distance, and the switching timing is immediate; otherwise, the gateway station enters the third judgment module;

[0016] The third judgment module of the gateway station is used to calculate the predicted position of the terminal at the next reporting time according to the current heading, speed and historical trajectory: if the predicted position is still within the coverage of the current beam and is not within the critical area of ​​the current beam switching, the terminal is notified that no switching is required; otherwise, the fourth judgment module of the gateway station is entered;

[0017] The fourth judgment module of the gateway station is used to calculate the distance between the predicted position of the terminal and the center point of each beam, and judge whether the distance between the predicted position and the center point of the current beam is the minimum: if so, notify the terminal that there is no need to switch; otherwise, calculate the time when the terminal enters the beam with the minimum distance according to the speed and heading, and notify the terminal to switch to the beam with the minimum distance.

[0018] Compared with the prior art, the present invention has the following significant advantages: (1) This method can solve the problem of beam switching during terminal movement; (2) Based on the terminal's location information, heading, speed, historical trajectory, original beam signal strength, original beam location information, adjacent beam location information, adjacent beam signal strength and other data, the target beam to be switched and the switching timing are comprehensively considered, thereby reducing the error caused by the terminal's calculation time and improving the accuracy of beam switching. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a flow chart of a multi-dimensional satellite beam switching method based on position prediction of the present invention. DETAILED DESCRIPTION

[0020] The present invention provides a multi-dimensional satellite beam switching method based on position prediction, comprising the following steps:

[0021] Step 1: The gateway receives the switching indicator sent by the terminal and stores the indicator sent by the terminal;

[0022] Step 2: The gateway determines whether the signal strength of the current beam is lower than the switching threshold, or whether the terminal is already in the current beam switching critical area: if yes, proceed to step 3; otherwise, notify the terminal that no switching is required;

[0023] Step 3: The gateway calculates the distance between the terminal's current position and the center points of each adjacent beam, and the distance between the current position and the center point of the current beam, and determines whether there is a beam with a smaller distance, and the signal strength of the beam with a smaller distance is higher than the signal strength of the current beam. If yes, the terminal is notified to switch, and the target beam is the beam with the smallest distance among the beams with a smaller distance, and the switching timing is immediate; otherwise, the process goes to step 4;

[0024] Step 4: The gateway calculates the predicted position of the terminal at the next reporting time based on the current heading, speed, and historical trajectory: If the predicted position is still within the coverage of the current beam and is not within the critical area of ​​the current beam switching, the terminal is notified that no switching is required; otherwise, it proceeds to step 5;

[0025] Step 5: The gateway calculates the distance between the terminal's predicted position and the center point of each beam, and determines whether the distance between the predicted position and the center point of the current beam is the minimum. If yes, the terminal is notified that there is no need to switch. Otherwise, the time for the terminal to enter the beam with the minimum distance is calculated based on the speed and heading, and the terminal is notified to switch to the beam with the minimum distance.

[0026] As a specific example, the gateway station in step 1 receives the switching indicator sent by the terminal and stores the indicator sent by the terminal, as follows:

[0027] Step 1.1, the gateway stores the position information of each beam;

[0028] Step 1.2, convert the position information of each beam into a plane coordinate system using an equal-area cylindrical projection method, and calculate the switching critical area;

[0029] Step 1.3, the gateway station represents each beam point in plane coordinates;

[0030] Step 1.4: The gateway receives and stores the switching indicator reported by the terminal.

[0031] As a specific example, the gateway described in step 1.1 stores the position information of each beam, which is as follows:

[0032] The gateway stores the position information of each beam:

[0033] Point P with longitude θ 1 ,latitude express:

[0034]

[0035] The beam center C is expressed as:

[0036]

[0037] Beam boundary Vertexs are represented as groups of vertices:

[0038] Vertexs = {P 1 ,P 2 ,…,P n}

[0039] The beam is represented by its boundaries and center point:

[0040] Beam={Vertexs,C}

[0041] As a specific example, the position information of each beam is converted into a plane coordinate system using an equal-area cylindrical projection method in step 1.2, and the switching critical area is calculated as follows:

[0042] Set the proximity switching distance dis;

[0043] For the beam coverage boundary polygon:

[0044] Vertexs = {P 1 ,P 2 ,…,P n}

[0045] Find the expression for each edge:

[0046] y=ax+b

[0047] Among them, x and y represent the x and y coordinate axes respectively;

[0048]

[0049]

[0050] (x n ,y n )、(x n+1 ,y n+1 ) represent the nth and n+1th coordinate points respectively;

[0051] Calculate the expression of the critical line that is inside the polygon and at a distance dis from the edge:

[0052] y=cx+d

[0053] in:

[0054] c=a

[0055]

[0056] Calculate the intersection point q(x,y of two adjacent critical lines, where:

[0057]

[0058]

[0059] The critical area is recorded as the strip area enclosed by the polygon whose vertex is the critical point and the beam coverage polygon:

[0060] V p = {q 1 ,q 2 ,…,q n}

[0061] As a specific example, the gateway described in step 1.3 represents each beam point in plane coordinates, as follows:

[0062] Points are expressed in plane coordinates:

[0063] R={x,y}

[0064] The beam center is expressed as:

[0065] M={x,y}

[0066] Beam boundaries are represented as groups of vertices:

[0067] V=R 1 ,R 2 ,…,R n}

[0068] The beam is represented by its boundaries and center point:

[0069] Beam={V,M}

[0070] As a specific example, the gateway described in step 1.4 receives and stores the handover indicator reported by the terminal, as follows:

[0071] The gateway receives the switching indicator T reported by the terminal:

[0072] T={Pos,Dir,Spe,CN c ,CNs n}

[0073] Where Pos is the current latitude and longitude of the terminal, Dir is the current heading of the terminal, Spe is the current speed of the terminal, CN c is the signal strength of the beam where the terminal is currently located, CNs n is the signal strength of the adjacent beam that can be received by the terminal.

[0074] As a specific example, the gateway described in step 2 determines whether the signal strength of the current beam is lower than the switching threshold, or whether the terminal is already located in the current beam switching critical area, and if so, proceeds to step 3; otherwise, notifies the terminal that no switching is required, as follows:

[0075] Step 2.1, draw two rays from the terminal reported position Pos in the opposite direction of the x-axis and the positive direction of the x-axis respectively, set count_left = 0, count_right = 0;

[0076] Step 2.2, calculate the intersection of the above two rays and each edge of the polygon. If there is an intersection in the opposite direction of the x-axis, count_left accumulates 1, otherwise count_right accumulates 1;

[0077] Step 2.3, if count_left and count_right are both odd numbers, the point is inside the polygon and the terminal is already in the current beam switching critical area; otherwise, the point is outside the polygon and the terminal is outside the current beam switching critical area;

[0078] Step 2.4: Determine whether the signal strength of the current beam is lower than the switching threshold. If the signal strength is higher than the switching threshold and is not within the switching critical area, notify the terminal that no switching is required; otherwise, proceed to step 3.

[0079] As a specific example, the gateway described in step 3 calculates the distance between the current position of the terminal and the center points of each adjacent beam, and the distance between the current position and the center point of the current beam, as follows:

[0080] The distance Dis between the terminal's current position and the center points of each adjacent beam, and the distance between the current position and the center point of the current beam, is calculated using the following formula:

[0081]

[0082] where x p is the x-axis coordinate of the terminal position; c is the x-axis coordinate of the beam center point; y p is the y-axis coordinate of the terminal position; c is the y-axis coordinate of the beam center point.

[0083] As a specific example, the gateway described in step 4 calculates the predicted position of the terminal at the next reporting time based on the current heading, speed, and historical trajectory, as follows:

[0084] Use polynomial fitting to combine the current position with speed and heading to predict the position. For the x-coordinate, the fitting polynomial result is:

[0085]

[0086] The input sample data is:

[0087] tt 1 ,t 2 ,…,t m ] T

[0088] xx 1 ,x 2 ,…,x m ] T

[0089] Where t is the time reported by the terminal;

[0090] Constructing the system of equations

[0091]

[0092] make

[0093]

[0094]

[0095]

[0096] Then the above system of equations can be written as:

[0097] Ab=f

[0098] Since t is time, the column vectors of A are linearly independent;

[0099] When m=n+1, A is a reversible matrix, then:

[0100] b=A -1 f

[0101] When m<n+1, the number of equations is less than the number of unknowns, the equations are unsolvable, the fitting fails, and a lower-order equation is used to fit again;

[0102] When m>n+1, use QR decomposition:

[0103] A [m,n+1] =Q [m,n+1] R [n+1,n+1]

[0104] but

[0105] QRb=f

[0106] but

[0107] Rb=Q T f

[0108] but

[0109] b=R -1 Q T f

[0110] The present invention also provides a multi-dimensional satellite beam switching device based on position prediction, comprising:

[0111] The gateway station receiving storage module is used to receive the switching indicator sent by the terminal and store the indicator sent by the terminal;

[0112] The first judgment module of the gateway station is used to judge whether the signal strength of the current beam is lower than the switching threshold, or whether the terminal is already in the current beam switching critical area: if yes, enter the second judgment module of the gateway station; otherwise, notify the terminal that no switching is required;

[0113] The second judgment module of the gateway station is used to calculate the distance between the current position of the terminal and the center point of each adjacent beam, and the distance between the current position and the center point of the current beam, and judge whether there is a beam with a smaller distance, and the signal strength of the beam with a smaller distance is higher than the signal strength of the current beam: if yes, the terminal is notified to switch, the target beam is the beam with the smallest distance in the beam with a smaller distance, and the switching timing is immediate; otherwise, the gateway station enters the third judgment module;

[0114] The third judgment module of the gateway station is used to calculate the predicted position of the terminal at the next reporting time according to the current heading, speed and historical trajectory: if the predicted position is still within the coverage of the current beam and is not within the critical area of ​​the current beam switching, the terminal is notified that no switching is required; otherwise, the fourth judgment module of the gateway station is entered;

[0115] The fourth judgment module of the gateway station is used to calculate the distance between the predicted position of the terminal and the center point of each beam, and judge whether the distance between the predicted position and the center point of the current beam is the minimum: if so, notify the terminal that there is no need to switch; otherwise, calculate the time when the terminal enters the beam with the minimum distance according to the speed and heading, and notify the terminal to switch to the beam with the minimum distance.

[0116] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0117] Example

[0118] Combination Figure 1 The present invention provides a multi-dimensional satellite beam switching method based on position prediction, comprising the following steps:

[0119] Step 1: The gateway receives the switching indicator sent by the terminal and stores the indicator sent by the terminal, as follows:

[0120] Step 1.1: The gateway stores the position information of each beam, as follows:

[0121] The gateway stores the position information of each beam:

[0122] Point P with longitude θ 1 ,latitude express:

[0123]

[0124] The beam center C is expressed as:

[0125]

[0126] Beam boundary Vertexs are represented as groups of vertices:

[0127] Vertexs = {P 1 ,P 2 ,…,P n}

[0128] The beam is represented by its boundaries and center point:

[0129] Beam={Vertexs,C}

[0130] Step 1.2: Convert the position information of each beam into a plane coordinate system using the equal-area cylindrical projection method, and calculate the switching critical area, as follows:

[0131] Set the proximity switching distance dis;

[0132] For the beam coverage boundary polygon:

[0133] Vertexs = {P 1 ,P 2 ,…,P n}

[0134] Find the expression for each edge:

[0135] y=ax+b

[0136] Among them, x and y represent the x and y coordinate axes respectively;

[0137]

[0138]

[0139] (x n ,y n )、(x n+1 ,y n+1 ) represent the nth and n+1th coordinate points respectively;

[0140] Calculate the expression of the critical line that is inside the polygon and at a distance dis from the edge:

[0141] y=cx+d

[0142] in:

[0143] c=a

[0144]

[0145] Calculate the intersection point q(x,y) of two adjacent critical lines, where:

[0146]

[0147]

[0148] The critical area is recorded as the strip area enclosed by the polygon whose vertex is the critical point and the beam coverage polygon:

[0149] V p = {q 1 ,q 2 ,…,q n}

[0150] Step 1.3: The gateway station represents each beam point in plane coordinates, as follows:

[0151] Points are expressed in plane coordinates:

[0152] R={x,y}

[0153] The beam center is expressed as:

[0154] M={x,y}

[0155] Beam boundaries are represented as groups of vertices:

[0156] V=R 1 ,R 2 ,…,R n}

[0157] The beam is represented by its boundaries and center point:

[0158] Beam={V,M}

[0159] Step 1.4: The gateway receives and stores the switching indicators reported by the terminal, as follows:

[0160] The gateway receives the switching indicator T reported by the terminal:

[0161] T={Pos,Dir,Spe,CN c ,CNs n}

[0162] Where Pos is the current latitude and longitude of the terminal, Dir is the current heading of the terminal, Spe is the current speed of the terminal, CN c is the signal strength of the beam where the terminal is currently located, CNs n is the signal strength of the adjacent beam that can be received by the terminal.

[0163] Step 2: The gateway determines whether the signal strength of the current beam is lower than the switching threshold, or whether the terminal is already in the current beam switching critical area. If yes, it proceeds to step 3; otherwise, it notifies the terminal that no switching is required, as follows:

[0164] Step 2.1, draw two rays from this point in the opposite direction of the x-axis and the positive direction of the x-axis respectively, set count_left = 0, count_right = 0;

[0165] Step 2.2, calculate the intersection of the above two rays and each edge of the polygon. If there is an intersection in the opposite direction of the x-axis, count_left accumulates 1, otherwise count_right accumulates 1;

[0166] Step 2.3, if count_left and count_right are both odd numbers, the point is inside the polygon and the terminal is already in the current beam switching critical area; otherwise, the point is outside the polygon and the terminal is outside the current beam switching critical area;

[0167] Step 2.4: Determine whether the signal strength of the current beam is lower than the switching threshold. If the signal strength is higher than the switching threshold and is not within the switching critical area, notify the terminal that no switching is required; otherwise, proceed to step 3.

[0168] Step 3: The gateway calculates the distance between the terminal's current position and the center of each adjacent beam, and the distance between the current position and the center of the current beam, and determines whether there is a smaller distance, and the signal strength of the smaller distance is higher than the signal strength of the current beam. If so, the terminal is notified to switch, the target beam is this beam, and the switching timing is immediately; otherwise, it goes to step 4;

[0169] Furthermore, the distance between the current position of the terminal and the center points of each adjacent beam, and the distance between the current position and the center point of the current beam are calculated as follows:

[0170] The distance Dis between the terminal's current position and the center points of each adjacent beam, and the distance between the current position and the center point of the current beam, is calculated using the following formula:

[0171]

[0172] where x p is the x-axis coordinate of the terminal position; c is the x-axis coordinate of the beam center point; y p is the y-axis coordinate of the terminal position; c is the y-axis coordinate of the beam center point.

[0173] Step 4: The gateway calculates the location of the terminal at the next reporting time based on the current heading, speed, and historical trajectory. If the predicted location is still within the coverage of the current beam and is not within the switching critical area, the terminal is notified that no switching is required; otherwise, the process goes to step 5.

[0174] Furthermore, the location of the terminal is calculated based on the current heading, speed, and historical trajectory for the next report, as follows:

[0175] Use polynomial fitting to combine the current position with speed and heading to predict the position. For the x-coordinate, the fitting polynomial result is:

[0176]

[0177] The input sample data is:

[0178] tt 1 ,t 2 ,…,t m ] T

[0179] xx 1 ,x 2 ,…,xm ] T

[0180] Where t is the time reported by the terminal;

[0181] Constructing the system of equations

[0182]

[0183] make

[0184]

[0185]

[0186]

[0187] Then the above system of equations can be written as:

[0188] Ab=f

[0189] Since t is time, the column vectors of A are linearly independent;

[0190] When m=n+1, A is a reversible matrix, then:

[0191] B -1 f

[0192] When mn+1, the number of equations is less than the number of unknowns, the equation is unsolvable, the fitting fails, and a lower-order equation is used to fit again;

[0193] When mn+1, use QR decomposition:

[0194] A [m,n+1] =Q [m,n+1] R [n+1,n+1]

[0195] Then QRb=f

[0196] Then Rb=Q T f

[0197] Then b=R -1 Q T f

[0198] Step 5: The gateway calculates the distance between the predicted terminal position and the center point of each beam, and determines whether there is a smaller distance. If so, it calculates the time when the terminal enters the beam based on the speed and heading, and notifies the terminal of the time to switch; otherwise, it notifies the terminal that there is no need to switch, as follows:

[0199] Calculate the distance between the predicted position and the center point of each beam, and select the minimum value of the distance to the center point of each adjacent beam. If this value is less than the distance to the center point of the current beam, calculate the time when the terminal enters the beam based on the speed and heading, and notify the terminal to switch. The target beam is this beam, and the switching timing is immediate; otherwise, notify the terminal that there is no need to switch.

[0200] The multi-dimensional satellite beam switching device based on position prediction in this embodiment includes:

[0201] The gateway station receiving storage module is used to receive the switching indicator sent by the terminal and store the indicator sent by the terminal;

[0202] The first judgment module of the gateway station is used to judge whether the signal strength of the current beam is lower than the switching threshold, or whether the terminal is already in the current beam switching critical area: if yes, enter the second judgment module of the gateway station; otherwise, notify the terminal that no switching is required;

[0203] The second judgment module of the gateway station is used to calculate the distance between the current position of the terminal and the center point of each adjacent beam, and the distance between the current position and the center point of the current beam, and judge whether there is a beam with a smaller distance, and the signal strength of the beam with a smaller distance is higher than the signal strength of the current beam: if yes, the terminal is notified to switch, the target beam is the beam with the smallest distance in the beam with a smaller distance, and the switching timing is immediate; otherwise, the gateway station enters the third judgment module;

[0204] The third judgment module of the gateway station is used to calculate the predicted position of the terminal at the next reporting time according to the current heading, speed and historical trajectory: if the predicted position is still within the coverage of the current beam and is not within the critical area of ​​the current beam switching, the terminal is notified that no switching is required; otherwise, the fourth judgment module of the gateway station is entered;

[0205] The fourth judgment module of the gateway station is used to calculate the distance between the predicted position of the terminal and the center point of each beam, and judge whether the distance between the predicted position and the center point of the current beam is the minimum: if so, notify the terminal that there is no need to switch; otherwise, calculate the time when the terminal enters the beam with the minimum distance according to the speed and heading, and notify the terminal to switch to the beam with the minimum distance.

[0206] The above are only preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A multi-dimensional satellite beam switching method based on position prediction, characterized in that: The following steps are involved: Step 1: The gateway receives the switching indicator sent by the terminal and stores the indicator sent by the terminal; Step 2: The gateway determines whether the signal strength of the current beam is lower than the switching threshold, or whether the terminal is already in the current beam switching critical area: if yes, proceed to step 3; otherwise, notify the terminal that no switching is required; Step 3: The gateway calculates the distance between the terminal's current position and the center of each adjacent beam, and the distance between the current position and the center of the current beam, and determines whether there is a beam with a smaller distance, and the signal strength of the beam with a smaller distance is higher than the signal strength of the current beam. If yes, the terminal is notified to switch, and the target beam is the beam with the smallest distance among the beams with the smallest distance, and the switching timing is immediately. Otherwise, go to step 4; Step 4: The gateway calculates the predicted position of the terminal at the next reporting time based on the current heading, speed, and historical trajectory: If the predicted position is still within the coverage of the current beam and is not within the critical area of ​​the current beam switching, the terminal is notified that no switching is required; otherwise, it proceeds to step 5; Step 5: The gateway calculates the distance between the predicted position of the terminal and the center point of each beam, and determines whether the distance between the predicted position and the center point of the current beam is the smallest. If yes, the terminal is notified that there is no need to switch. Otherwise, the time when the terminal enters the minimum distance beam is calculated according to the speed and heading, and the terminal is notified to switch to the minimum distance beam. The gateway station in step 1 receives the switching indicator sent by the terminal and stores the indicator sent by the terminal, which is specifically as follows: Step 1.1, the gateway stores the position information of each beam; Step 1.2, convert the position information of each beam into a plane coordinate system using an equal-area cylindrical projection method, and calculate the switching critical area; Step 1.3, the gateway station represents each beam point in plane coordinates; Step 1.4, the gateway receives and stores the switching indicator reported by the terminal; The gateway described in step 1.1 stores the position information of each beam, which is as follows: The gateway stores the position information of each beam: Point P is at longitude θ1, latitude express: The beam center C is expressed as: Beam boundary Vertexs are represented as groups of vertices: Vertexs={P1,P2,…,P n } The beam is represented by its boundaries and center point: Beam={Vertexs,C} In step 1.2, the position information of each beam is converted into a plane coordinate system using the equal-area cylindrical projection method, and the switching critical area is calculated as follows: Set the proximity switching distance dis; For the beam coverage boundary polygon: Vertexs={P1,P2,…,P n } Find the expression for each edge: y=ax+b Among them, x and y represent the x and y coordinate axes respectively; (x n ,y n )、(x n+1 ,y n+1 ) represent the nth and n+1th coordinate points respectively; Calculate the expression of the critical line that is inside the polygon and at a distance dis from the edge: y=cx+d in: c=a Calculate the intersection point q(x,y) of two adjacent critical lines, where: The critical area is recorded as the strip area enclosed by the polygon whose vertex is the critical point and the beam coverage polygon: V p ={q1,q2,…,q n } The gateway described in step 1.3 represents each beam point in plane coordinates, as follows: Points are expressed in plane coordinates: R={x,y} The beam center is expressed as: M={x,y} Beam boundaries are represented as groups of vertices: V={R1,R2,…,R n } The beam is represented by its boundaries and center point: Beam={V,M} The gateway described in step 1.4 receives and stores the switching indicator reported by the terminal, as follows: The gateway station receives the handover metric T reported by the terminal: T={Pos,Dir,Spe,CN c ,CNs n } Where Pos is the current latitude and longitude of the terminal, Dir is the current heading of the terminal, Spe is the current speed of the terminal, CN c is the signal strength of the beam where the terminal is currently located, CNs n is the signal strength of the adjacent beam that can be received by the terminal; The gateway station described in step 2 determines whether the signal strength of the current beam is lower than the handover threshold, or whether the terminal has already been located within the handover critical area of the current beam. If so, it proceeds to step 3; otherwise, it notifies the terminal that no handover is required, as follows: Step 2.1: Draw two rays from the position Pos reported by the terminal, one in the negative x-axis direction and the other in the positive x-axis direction, and set count_left = 0 and count_right = 0; Step 2.2: Calculate the intersection points of the two rays with each side of the polygon. If there is an intersection point in the negative x-axis direction, count_left is incremented by 1; otherwise, count_right is incremented by 1; Step 2.3: If both count_left and count_right are odd, the point is inside the polygon and the terminal has already been located within the handover critical area of the current beam; otherwise, the point is outside the polygon and the terminal is located outside the handover critical area of the current beam; Step 2.4: Determine whether the signal strength of the current beam is lower than the handover threshold. If the signal strength is higher than the handover threshold and the terminal is not located within the handover critical area, it notifies the terminal that no handover is required; otherwise, it proceeds to step 3; The gateway station described in step 3 calculates the distances between the current position of the terminal and the center points of each adjacent beam, and the distance between the current position and the center point of the current beam, as follows: The distance Dis calculation formula for the distances between the current position of the terminal and the center points of each adjacent beam, and the distance between the current position and the center point of the current beam, is: where x p is the x-axis coordinate of the terminal position; c is the x-axis coordinate of the beam center point; y p is the y-axis coordinate of the terminal position; c is the y-axis coordinate of the beam center point; The gateway station described in step 4 calculates the predicted position of the terminal at the next report based on the current heading, speed, and historical trajectory, as follows: Use polynomial fitting combined with the current position, speed, and heading for position prediction. For the x coordinate, the result of the fitted polynomial is: The input sample data is: t=[t1,t2,…,t m ] T x=[x1,x2,…,x m ] T where t is the time reported by the terminal; Construct the system of equations Let Then the above system of equations is written as: Ab = f Since t is time, each column vector of A is linearly independent; When m = n + 1, A is an invertible matrix, then: b=A -1 f When m < n + 1, the number of equations is less than the number of unknowns, the equation is unsolvable, the fitting fails, and a lower-degree equation is used for fitting again; When m > n + 1, use QR decomposition: A [m,n+1] =Q [m,n+1] R [n+1,n+1] Then QRb = f Then Rb=Q T f Then b=R -1 Q T f。 2. A multi-dimensional satellite beam switching device based on position prediction, characterized in that: The device is used to implement the multi-dimensional satellite beam handover method based on position prediction described in claim 1. The device includes: A gateway station receiving and storing module, which is used to receive the handover metrics sent by the terminal and store the metrics that the terminal has already sent; A gateway station first judgment module, which is used to judge whether the signal strength of the current beam is lower than the handover threshold, or whether the terminal has already been located within the handover critical area of the current beam: if so, it proceeds to the gateway station second judgment module; otherwise, it notifies the terminal that no handover is required; A gateway station second judgment module, which is used to calculate the distances between the current position of the terminal and the center points of each adjacent beam, and the distance between the current position and the center point of the current beam, and judge whether there is a beam with a smaller distance, and the signal strength of the beam with the smaller distance is higher than the signal strength of the current beam: if so, it notifies the terminal to perform a handover, the target beam is the beam with the smallest distance among the beams with the smaller distances, and the handover timing is immediately; otherwise, it proceeds to the gateway station third judgment module; The third judgment module of the gateway station is used to calculate the predicted position of the terminal at the next reporting time according to the current heading, speed and historical trajectory: if the predicted position is still within the coverage of the current beam and is not within the critical area of ​​the current beam switching, the terminal is notified that no switching is required; otherwise, the fourth judgment module of the gateway station is entered; The fourth judgment module of the gateway station is used to calculate the distance between the predicted position of the terminal and the center point of each beam, and judge whether the distance between the predicted position and the center point of the current beam is the minimum: if so, notify the terminal that there is no need to switch; otherwise, calculate the time when the terminal enters the minimum distance beam according to the speed and heading, and notify the terminal to switch to the minimum distance beam.

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