CN114039655B - Inter-satellite route survivability method based on link prediction and region division - Google Patents
Inter-satellite route survivability method based on link prediction and region division Download PDFInfo
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Abstract
The invention belongs to the technical field of satellite communication, and relates to an inter-satellite route destruction-resistant method based on link prediction and region division; when a satellite has periodic faults, namely the faults occur in links between orbits and the satellite is in a polar region, determining a fault recovery period based on the on-off rule of the links, and updating the faulty links in advance; when a satellite has a random fault, carrying out autonomous area division according to the position of the fault, and executing a route destruction-resistant strategy; if the fault occurs in the inter-orbit link and the satellite is not in the polar region, the fault satellite performs single-hop flooding and regional fusion to the neighboring satellite of the fault satellite; if a failure occurs in an in-orbit link, the failed satellite broadcasts an area to all satellites in the same orbit. The invention divides different running states and fault types among satellites, adopts different routing mechanisms to provide the optimal path under the current network condition, reduces the resource expenditure and routing loop of path calculation, and reduces network packet loss.
Description
Technical Field
The invention belongs to the technical field of satellite communication, and particularly relates to an inter-satellite routing survivability method based on link prediction and region division.
Background
A Low Earth Orbit (LEO) satellite constellation network will be an important component of the next generation communication infrastructure. Low earth orbit satellite constellation networks using inter-satellite links (ISLs) can be immune to geographic obstructions and independent of ground infrastructure. However, research and selection of routing algorithms, whether conventional terrestrial networks or today's satellite networks, are always in important locations.
Meanwhile, in the satellite network, space navigation level chips are used by on-board equipment in the space information network, the computing capacity, the memory capacity and the like of the space navigation level chips are greatly limited, moreover, the poor operation environment of the satellite network can lead to unstable satellite link connection, the position of a fault link needs to be detected immediately after the link breaks down, and countermeasures are taken for the fault condition in the route recovery technology so as to achieve the aim of efficiently and timely recovering communication.
The common satellite network anti-destruction routing technology processes the fault information of the satellite by adopting the global flooding mode of OSPF and RIP, namely, the routing protocol interacts network topology information when the connection is established or changed, and a routing table is rebuilt. However, satellite networks have the characteristic of moving at high speed compared to terrestrial networks, resulting in rapid changes in network topology, very fast expiration of topology information and the need for frequent refreshing. The processing overhead of the algorithm is large, so that the algorithm is more difficult to be suitable for satellite networks.
The local flooding representation is an ant colony algorithm, the algorithm adopts a method for detecting data packets to perform fault treatment, the fault information of the passed satellite is collected and added into the detected data packets in the process of going to a destination, and the detected data packets are returned according to the original route and simultaneously are subjected to route calculation after reaching the destination point. However, due to the high dynamics of satellites and the depth of detection being related to the number in the satellite network, it is difficult to guarantee the timeliness of the computation.
Therefore, in order to ensure that the satellite network can provide stable and reliable communication service, a core problem is how to implement timely and accurate link failure prediction and a flexible and efficient route survivability scheme.
Disclosure of Invention
In order to solve the problems, the invention provides an inter-satellite routing survivability method based on link prediction and region division, which is mainly used between Low Earth Orbit (LEO) satellite constellation networks, and is used for ensuring that different services can still provide an effective routing path and ensure stable forwarding of data and reduce occupation of on-satellite resources when encountering link faults under the satellite networks.
An inter-star route survivability method based on link prediction and region division, the method comprising:
when the satellite has periodic faults, namely the faults occur in the inter-orbit links and the satellite is in the polar region, determining a fault recovery period based on the on-off rule of the links, and updating the fault links in advance;
when a satellite has a random fault, carrying out autonomous area division according to the position of the fault, and executing a route destruction-resistant strategy; if the fault occurs in the inter-orbit link and the satellite is not in the polar region, the fault satellite performs single-hop flooding and regional fusion to the neighboring satellite of the fault satellite; if a failure occurs in an in-orbit link and whether the satellite is in polar region or not, the failed satellite regional broadcasts to all satellites in the same orbit.
The invention has the beneficial effects that:
1. according to the method, the route updating and the route judging are carried out based on the periodicity and the regularity of satellite movement, so that frequent information interaction of different satellites in a polar region can be reduced, the problem that a route table cannot be updated immediately due to global flooding is avoided, meanwhile, when a random link failure occurs in the satellite, an effective route path can be provided through local flooding, and the overall benefit maximization of satellite network resources is realized.
2. The invention divides different running states and fault types among satellites, and adopts different routing mechanisms to provide the optimal path under the current network condition, thereby reducing the resource expenditure and routing loop of path calculation and reducing network packet loss.
Drawings
FIG. 1 is a schematic view of a low-orbit satellite according to an embodiment of the present invention;
FIG. 2 is a flowchart of an inter-satellite route survivability method based on link prediction and region division in an embodiment of the invention;
FIG. 3 is a topology diagram of a satellite network based on virtual ID numbers according to an embodiment of the present invention;
FIG. 4 is a block diagram of a time slice according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of random faults occurring within a track in an embodiment of the present invention;
FIG. 6 is a schematic diagram of random faults occurring between tracks in an embodiment of the present invention;
FIG. 7 is a schematic diagram of a sub-node also generating random faults in an embodiment of the present invention;
FIG. 8 is a schematic diagram of region fusion of sub-nodes in an embodiment of the present invention;
FIG. 9 is a flow chart of an inter-satellite route survivor method based on link prediction and region partitioning in a preferred embodiment of the invention;
fig. 10 is a flowchart of an inter-star route survivor method based on link prediction and region division in another preferred embodiment of the invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
FIG. 1 is a schematic view of a low-orbit satellite according to an embodiment of the present invention; as shown in fig. 1, a typical low-orbit satellite network scenario in which the present invention is applied is not limited thereto; the low-orbit satellite network of the embodiment of the invention comprises 5 orbit planes, each orbit plane contains 4 satellites, and the ith satellite is positioned on the ith orbitj satellites are marked as S i,j Each satellite establishes a connection with its neighboring satellites. Each satellite, except for the satellites in the edge orbit, contains two inter-satellite links and two intra-orbit links. The first and fifth orbital planes maintain only three inter-satellite links for satellites in the plane due to the presence of the reverse slot. And meanwhile, when the latitude of the satellite is higher than 70 degrees, the inter-satellite link between the horizontal planes is closed because the relative movement speed of the satellite is too high. For simplicity, all LEO satellites are indexed in XY format, where X represents the orbital plane from 1 to 5 and Y represents the satellites in X orbit from 1 to 4. All satellites act as routers, forming a local routing table, using a dedicated routing protocol in the satellite network.
In the invention, the link faults of satellites are mainly divided into two major categories, one category is periodic faults caused by the periodicity and regularity of satellite motion, and the other category is random faults caused by other emergency, so the invention respectively processes the periodic faults and the random faults in different modes to solve the problem of inter-satellite route destruction resistance.
Fig. 2 is a flowchart of an inter-star route survivability method based on link prediction and region division in an embodiment of the present invention, as shown in fig. 2, where the method includes:
101. when the satellite has periodic faults, namely the faults occur in the inter-orbit links and the satellite is in the polar region, determining a fault recovery period based on the on-off rule of the links, and updating the fault links in advance;
102. when a satellite has a random fault, carrying out autonomous area division according to the position of the fault, and executing a route destruction-resistant strategy; if the fault occurs in the inter-orbit link and the satellite is not in the polar region, the fault satellite performs single-hop flooding and regional fusion to the neighboring satellite of the fault satellite; if a failure occurs in an in-orbit link and whether the satellite is in polar region or not, the failed satellite regional broadcasts to all satellites in the same orbit.
In the embodiment of the invention, before periodical faults and random faults occur, the virtual topology is required to be constructed, and corresponding survivability strategies are executed when the periodical faults or/and the random faults occur based on the virtual topology, wherein the construction process of the virtual topology comprises the following steps:
setting a virtual ID number for each satellite in the satellite initialization configuration, wherein the virtual ID number comprises an orbit number and an in-orbit number of the satellite; each satellite can calculate the number of the orbit in which the satellite is located and the number in the orbit according to the virtual ID number, and the set of the orbit numbers in which the satellite is located is assumed to be I= (I) 1 ,i 2 ,…,i M ) M is the maximum number of the track surface, and the number set in the track is J= (J) 1 ,j 2 ,…,j N ) N is the largest number in orbit, the virtual ID number t= (I, J) of the satellite is determined so that each satellite determines the addresses of neighboring satellites around itself according to its own virtual ID number, as shown in fig. 3, fig. 3 shows a partial topology structure, each satellite has 4 neighborhoods, specifically including neighboring satellites in four directions of front, back, left and right, assuming that the current satellite is (3, 2), then its neighboring satellites are (2, 2), (4, 2), (3, 1) and (3, 3), and because the relative positions of the satellite networks are basically fixed, the nodes that the satellite can communicate with are at most two satellites in front and back in orbit (upper and lower satellites in fig. 3) and left and right between neighboring orbits, then the satellites in orbit with the current satellite (3, 2) are (3, 1), (3, 3) and (3, 4), and the satellites in adjacent orbits with the current satellite (3, 2) are (2, 2) and (4, 2).
In the embodiment of the invention, the topology model of the satellite constellation system can be equivalent to a connected regular checkerboard diagram, and because the data packet can only travel inter-satellite links in the orbit or inter-satellite links between the orbits when being transmitted in the satellite network, the Manhattan minimum distance between any two satellites (m, n) to (x, y) is equal under the condition that the links are connected and no other faults exist.
c＝|i m -i x |+|j n -j y |
Wherein c represents Manhattan minimum distance, i m An orbit number representing the satellite (m, n); i.e x An orbit number representing the satellite (x, y); j (j) n An in-orbit number representing the satellite (m, n); j (j) y Representing the in-orbit number of satellite (x, y)。
Therefore, based on the analysis, the invention can determine the position of the next hop data packet transmission routing node according to the virtual ID (m, n) of the destination satellite in the received data packet and the state information of the associated link. If the inter-orbit parameter m of the target satellite ID is larger than the inter-orbit parameter x of the current relay node, transmitting to the right, otherwise, transmitting to the left; secondly, judging the parameter N in the orbit, wherein the number of satellite nodes in the orbit is N, if the absolute value difference between the parameter N in the orbit of the target satellite and the satellite nodes in the relay point is less than half of the number of the satellites in the orbit, the satellite nodes are transmitted downwards in the same orbit (the reverse direction of the satellite operation), otherwise, the satellite nodes are transmitted upwards in the same orbit; if the absolute value of the parameter n in the orbit of the target satellite and the relay point is greater than half of the number of the satellites in the orbit, the satellite is transmitted upwards in the same orbit, otherwise, the satellite is transmitted upwards in the same orbit.
In the embodiment of the invention, each satellite maintains a link state table to store the random fault information in the known satellite network link, and simultaneously maintains a network adjacency matrix for route calculation to update the route table; meanwhile, a transfer mechanism of a Hello data packet of an OSPF protocol is added to generate a neighbor list for maintaining the relationship between a satellite node and a neighbor satellite, so that normal communication among satellites is ensured.
In the embodiment of the invention, in order to solve the problem of route destruction caused by periodic faults of the satellite, the invention divides time slices according to the operation rule of the satellite and uploads a link state table of a corresponding satellite network; when the satellite is operating normally, topology snapshots about the satellite network are continuously received from the gateway station, triggering route updates for handling the satellite entry and exit areas.
As shown in fig. 4, the present invention first defines N times of topology change of a satellite network as a set t= (T) 0 ,t 1 ,…,t N ) Wherein each time point is the moment of a topology change and the time interval t is split i ,t i+1 ]Representing the moment of transformation of a certain inter-orbit link in the satellite network, the corresponding N snapshot slices are p= (P) 0 ,p 1 ,…,p N )；Because the satellite has the problem of frequent switching of links when entering and exiting the polar region, the condition that a plurality of satellite links are disconnected simultaneously can be caused, the time slice of the time period, namely p, is abandoned i+1 ＝p i+2 The method comprises the steps of carrying out a first treatment on the surface of the At this time, the topology condition of the network is added into the adjacency matrix for route calculation in advance, and the route update is triggered when the satellite enters and exits the polar region.
In the present invention, due to the transition time slices p i+1 Is generated, p i And p is as follows i+1 There is a switching interval and the transition time slice p needs to be restarted in order to ensure the switching stability i+1 Is a transition time of (a). Let p be i+1 The original transformation time of (1) is t p The time interval to be adjusted is Δτ (Δτ<<t p ) If the data packet is at t p Emitted at the moment of Δτ, for a period of Δτ, just before t p The moment is that the destination end is reached, at the moment, the time is just t p When the time passes through the link which is already on-off, the data packet is lost. The advance time of the snapshot can be obtained according to the maximum delay of the network at the moment, the number of satellites on the same track surface at the moment is set as M, the number of satellites in the same track is set as N, and at the moment, the satellites in the same track can respectively enter the north-south regions of the earth, so that the maximum average hop number is as follows: u= (m+n)/3; meanwhile, the transmission time of a satellite link is set as Ta, the processing time delay of a satellite node is set as Tb, and the maximum delay time delay of a satellite network is set as T-delta-sigma (Ta+Tb) U; simultaneous time slices p i+1 To p i+2 There will also be some switching interval, but due to p i+2 Has been p i+1 By logging in advance, errors currently caused by the switching interval can be avoided.
In the embodiment of the invention, in order to solve the route destruction resistance of the satellite with random faults, the invention carries out autonomous area division according to the position of the faults, and executes the route destruction resistance strategy according to the result of autonomous area division; firstly, judging that the position of a satellite with a random fault is an inter-orbit link or/and an in-orbit link, and dividing the current satellite and the satellite in the same orbit into autonomous areas if the random fault is in the in-orbit link; if the random faults occur in the inter-orbit links, all the neighborhood satellites of the current satellite and the opposite satellite with the inter-orbit link faults are divided into autonomous areas.
In the invention, the failure degree of random failure is mainly judged from the capacity of a link and the point storage space, and the flow of a satellite node and a neighbor node is defined as follows:
where M represents the set of neighbor nodes of the satellite and τ represents the time gap.
Definition of link capacityRepresenting the flow of data flow Mi over link uv, the capacity constraint can be expressed as:
in the above-mentioned method, the step of,representing the link (u, v) at τ q Maximum transmission capacity within, w uv And (t) is the bandwidth of the link.
Thus, in view of the above capacity constraints, the utility function of link capacity can be defined as:
for the storage space of the node, it is assumed that the satellite node vmax buffer size is B v For intermediate node v, its data stream entry and output affects its buffer queue length, for τ 1 The buffer queue length of satellite node v can be expressed as:
for time gap τ q The calculation of the buffer queue length of the satellite node v should also take into account the amount of buffered data in the previous time interval, which can be expressed as:
thus, due to the limited buffer size of the satellite nodes, the total amount of buffered data in any one time interval should be smaller than the maximum buffer size B of the satellite nodes v ：
Based on the above analysis, the node storage space constraints can be expressed as:
thus, in view of the above storage space constraints, the utility function of the buffer queue may be defined as:
the utility function U (c), U (b) can be obtained through modeling analysis of the link capacity and the storage space, and each utility function value is between [0,1]. The link quality utility value for the satellite can be expressed as:
because U (c), U (b) is between [0,1]Thus the link utility value U i ∈[0,1]，Weights for link capacity and storage space decision attributes, respectively, and satisfy +.>And adjusting according to the processing capacity of the satellite. The satellite node S (m, n) records the minimum value of the link quality utility value, j represents the order of the records, namely:
when U is j (S(m,n))-U j-1 (S (m, n))isless than or equal to 0 and j is more than or equal to 2, then the current satellite is considered to have random faults, and a destruction-resistant strategy is needed to be adopted; when U is j (S (m, n)). Apprxeq.0, a destroy-resistant policy, i.e., sending a destroy-resistant request packet, is also required.
In order to accurately divide the autonomous region, the connectivity between satellite nodes is accurately described, and the concept of direction degree is introduced according to the relation between the current satellite S (m, n) and the 4 neighborhood of the satellite S (m, n):
let L x+ (m,n)，L x- (m,n)，L y+ (m,n)，L y- (m, n) indicates the left, right, forward, and backward degrees of direction of the current satellite S (m, n), respectively, and the subscript x indicates the horizontal direction and the y vertical direction.
Simultaneously, the method comprises the following steps:
then there are:
the same principle can be obtained:
thus, the total first direction degree L (m, n) and the second direction degree L * (m, n) are respectively:
in the embodiment of the invention, the first direction degree L (m, n) and the second direction degree L are used for * (m, n) judging the link fault degree of the current satellite:
firstly, the current satellite S (m, n) detects all link interface conditions of the node through the MAC layer to obtain the direction degree L x+ (m,n)，L x- (m,n)，L y+ (m,n)，L y- (m, n).
If all links of the current satellite and the 4 neighborhood satellites fail, namely the second direction degree L * (m, n) =0 and the first direction degree L (m, n) =0, then the satellite S (m, n) is considered to be completely invalid, and then the neighbor satellite generation of the current satellite is used for transmitting the anti-destruction request packet;
if the partial link between the current satellite and the 4 neighborhood satellite fails, namely L * (m, n) =0 and L (m, n) +.0, then the current satellite is subject to a survivor policy based on where the link failure occurred.
In the invention, because only random faults in the orbits are considered when the satellites are in the polar regions (faults among the orbits are processed by adopting a time slice mechanism), regional division and flooding are needed, and if the faults occur in links among the orbits and the satellites are not in polar regions, the faulty satellites perform single-hop flooding and regional fusion to neighbor satellites of the faulty satellites; if a failure occurs in an in-orbit link and whether the satellite is in polar region or not, the failed satellite regional broadcasts to all satellites in the same orbit.
In the embodiment of the invention, when the fault occurs in the in-orbit link, whether the satellite is in the polar region or not is not considered, namely if L y+ (m, n) =0 or L y- (m, n) =0, then the current satellite performs regional broadcast to all satellites in the same orbit, and then the satellite associated with the faulty link is made to perform regional broadcast to all nodes in the orbit as a parent node, so as to determine the location of the link fault. And meanwhile, the node which receives the fault information is marked as a child node.
Specifically, as shown in fig. 5, the current satellite < m, n > and the opposite satellite < m, n-1> that have an in-orbit link failure transmit link state data packets to all neighboring satellites within the autonomous region, that is, within the current orbit m, respectively, by broadcasting, and the parent node a < m, n > transmits link failure information to the child nodes < m, n+1> and < m, n+2>, and the parent node B < m, n-1> transmits link failure information to the child nodes < m, n-2>, thereby forming the autonomous region within the orbit as shown in fig. 5.
And judging whether the adjacent satellite, namely the child node < m, n+1>, the child node < m, n+2> and the child node < m, n-2> of the link state data packet generate link faults or not, analyzing the link state data packet and judging whether the analyzed in-orbit link faults exist or not if the link faults do not occur, adding the link state data packet into a link state table of the adjacent satellite, generating an adjacent matrix for route update, executing a D algorithm according to the adjacent matrix to calculate the shortest path, and updating a route table.
In the embodiment of the invention, for the fault occurring in the inter-orbit link and the satellite not in the polar region, namely the current satellite and the left and right neighborhood sanitation thereofInter-track link failure of star link, i.e. if L x+ (m, n) =0 or L x- (m, n) =0, then the current satellite performs single-hop flooding and region fusion to its own neighbor satellite; the method comprises the steps that a current satellite and an opposite-end satellite with inter-orbit link faults send link state data packets to all neighbor satellites in an autonomous area respectively, the neighbor satellites receiving the link state data packets judge whether the link faults occur or not, if the link faults do not occur, the link state data packets are analyzed, whether the analyzed inter-orbit link faults exist or not is judged, if the link faults do not exist, the link state table is added to the link state table of the current satellite and an adjacent matrix used for route updating is generated, a D algorithm is executed according to the adjacent matrix to calculate the shortest path, a route table is updated, whether links parallel to the failed inter-orbit links exist or not is detected by all satellites in the autonomous area, the parallel links are closest to the manhattan distance of the detected satellites, if the link faults exist, information interaction is carried out on all satellites related to the link, the other satellites are added into a waiting list of the satellites, and flooding is carried out according to the satellites in the waiting list.
In the above embodiment, the present invention further determines whether the fault information is recorded in the current link state table of the satellite, and if so, does not perform any operation, otherwise, stores the invalid link information into the link state table of the satellite itself, then changes the network adjacency matrix of the satellite itself, and performs the algorithm D according to the adjacency matrix to calculate the shortest path to the rest of satellite nodes in the satellite network, and updates the routing table. In the embodiment of the invention, in order to facilitate the determination of the position of the fault and the processing of the flooding message, the node with the link fault is called a parent node, and the node receiving the link state data packet sent by the parent node is called a child node. The link state data packet contains the virtual ID number of the parent node, the location of the failed link, the status of the failed link. And generating an adjacency matrix W for route update according to the received fault information:
while setting up a pending list (the pending list of a parent node contains its own neighbor nodes by default) and an adjacency matrix in the network for each node. The pending list refers to which satellites should be flooded with a link state data packet after a node receives the data packet, which is used to ensure that satellites in an autonomous region all receive the same link state information, i.e. ensure route convergence in the region.
And if the position of the failed link is positioned between the tracks, sending a link state data packet to the neighbor node which does not generate the link failure. As shown in fig. 6, when the link { < m, n >, < m+1, n > }, the parent node a and the parent node B need to transmit failure information to respective neighboring satellites, the neighboring satellites of the parent node a < m, n > transmitting the link state data packet are nodes < m-1, n >, nodes < m, n+1> and nodes < m, n-1>, and the neighboring satellites of the parent node B < m+1, n > transmitting the link state data packet are nodes < m+1, n-1>, nodes < m+2, n > and nodes < m+1, n+1>, at which time a preliminary autonomous region is formed.
If each child node detects a link failure at this time, the child node informs the parent node of the current satellite of own failure information, and repeats the above operation, and at this time, the node is identified as a new parent node, and needs to inform the child node of new failure information received from other parent nodes, and inform the parent node of own failure information. And adding the parent node to the own pending list. As shown in FIG. 7, when the child node C < m, n+1> also fails randomly, the node needs to flood the failure information to the parent node A < m, n >, node < m-1, n+1> and node < m, n+2>. Otherwise, the child node will detect whether the fault information appears in its own link state table, if not, it adds into its own link state table, then changes its own network adjacent matrix, and executes D algorithm according to the adjacent matrix to calculate the shortest path to other satellite nodes in the satellite network, and updates the routing table. If so, no action is taken.
And then, the child node detects whether a link which is parallel to the fault link and has the nearest Manhattan distance to the fault link exists in the current network topology, if so, the child node associated with the link performs information interaction, and the other party is added into a waiting list of the child node. The goal of flooding is to nodes in the list to be transmitted. As shown in FIG. 8, nodes E < m, n-1> and F < m+1, n-1> need to perform information interaction, and nodes C and D are the same, so that area fusion is formed, the closure of the autonomous area is ensured, and a routing loop is avoided.
If the link state table of the satellite has old fault information and the fault link corresponding to the old fault information is still in a disconnected state, the fault information still needs to be flooded, the link connection relation between the current satellite and the 4 neighborhood of the satellite is re-detected, and the unification and the fusion of the fault information of different areas are ensured.
In the above process, when two nodes which have originally had a link failure can continue to interact with the Hello data packet, it is proved that the link has recovered, and it is necessary to notify nodes in the autonomous region that the failed link has recovered, change the state of the link in the link state table of the nodes, update the route, generate a new link state data packet, and send the link state data packet to all nodes in the pending list.
When the links which send random faults in the link state tables of the nodes are all recovered to be normal, the waiting list of the nodes is required to be emptied, the corresponding information in the link state tables and the adjacent matrix is required to be emptied, only the information in the time slices is reserved, and the initial state of the satellite nodes is recovered.
Fig. 9 is a flowchart of an inter-star route survivor method based on link prediction and region division in a preferred embodiment of the present invention, as shown in fig. 9, and in an embodiment of the present invention, the method includes:
setting a virtual ID for each satellite according to the operation rule of the satellite, and constructing a virtual topological structure;
time slice division is performed based on intervals of intermittent links to update periodic fault links in advance;
in the real-time process, whether the satellite link has a random fault or not needs to be judged, and if the satellite link has the random fault, whether the random fault has an inter-track link or not needs to be judged;
if the random fault occurs in the inter-orbit link, the satellite node with the link fault can broadcast the area to all satellites in the same orbit to update the random link fault;
if the random fault is not an inter-orbit link, the random fault is shown to occur in an in-orbit link, at the moment, whether the satellite node is in a polar region or not needs to be continuously judged, if so, the link fault is directly updated, and if not, the satellite node with the link fault can perform single-picking flooding and region fusion to the neighboring node of the satellite node to update the random link fault.
Fig. 10 is a flowchart of an inter-star route survivor method based on link prediction and region division according to another preferred embodiment of the present invention, and as shown in fig. 10, in an embodiment of the present invention, the method includes:
satellite initialization configuration, namely setting a virtual ID number according to the position of a satellite node in satellite topology;
the hello data packet of the OSPF protocol is adopted between satellites to maintain the contact between the satellites and the neighbor satellites, so that the communication between the satellites is ensured;
according to the operation rule of the satellite, the topology of the satellite network is time-divided, and the last information of the gateway station is passed;
the satellite node judges whether the satellite node is in a polar region according to the link state, if so, a routing table with the shortest path is generated according to the link state table to obtain a next-hop satellite, and if not, whether the satellite node has a link fault is directly judged;
if the link fault occurs, flooding is carried out to the affected satellite nodes according to the position of the link fault, so as to determine the area affected by on-off, and the flooding is ended; and updating the flooding information into the link state table of the device to generate a routing table with the shortest path so as to obtain the next-hop satellite.
And if no link failure occurs, obtaining the next-hop satellite directly according to the Manhattan shortest algorithm.
In the description of the present invention, it should be understood that the terms "coaxial," "bottom," "one end," "top," "middle," "another end," "upper," "one side," "top," "inner," "outer," "front," "center," "two ends," etc. indicate or are based on the orientation or positional relationship shown in the drawings, merely to facilitate description of the invention and simplify the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the invention.
In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "configured," "connected," "secured," "rotated," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intermediaries, or in communication with each other or in interaction with each other, unless explicitly defined otherwise, the meaning of the terms described above in this application will be understood by those of ordinary skill in the art in view of the specific circumstances.
Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (6)
1. An inter-satellite route survivability method based on link prediction and region division, which is characterized by comprising the following steps:
when the satellite has periodic faults, namely the faults occur in the inter-orbit links and the satellite is in the polar region, determining a fault recovery period based on the on-off rule of the links, and updating the fault links in advance;
when a satellite has a random fault, carrying out autonomous area division according to the position of the fault, and executing a route destruction-resistant strategy; if the fault occurs in the inter-orbit link and the satellite is not in the polar region, the fault satellite performs single-hop flooding and regional fusion to the neighboring satellite of the fault satellite; if the fault occurs in the in-orbit link and whether the satellite is in the polar region or not, the fault satellite broadcasts the region to all satellites in the same orbit;
when the satellite has a random fault, the autonomous area division is carried out according to the position of the fault, wherein the autonomous area division comprises judging that the position of the satellite with the random fault is an inter-orbit link or/and an intra-orbit link, and if the random fault occurs in the intra-orbit link, dividing the current satellite and the satellite in the same orbit into autonomous areas; if the random faults occur in the inter-orbit links, dividing all neighborhood satellites of the current satellite and the opposite satellite with the inter-orbit link faults into autonomous areas;
the route survivability strategy comprises calculating the direction degree value L of the current satellite (m, n) in the 4 neighborhood according to the connectivity of the satellite and the neighboring satellite x+ (m,n)，L x- (m,n)，L y+ (m,n)，L y- (m, n), summing the direction degree values of the 4 neighborhoods to calculate the first direction degree L (m, n) of the current satellite, and obtaining the second direction degree L by the product of the direction degree values of the 4 neighborhoods * (m, n); judging the link failure degree of the current satellite according to the first direction degree and the second direction degree, if all links of the current satellite and 4 neighborhood satellites of the current satellite are failed, namely L * (m, n) =0 and L (m, n) =0, then the neighbor satellite of the current satellite is instead transmitting the survivor request packet; if the partial link between the current satellite and the 4 neighborhood satellite fails, namely L * (m, n) =0 and L (m, n) +.0, then sending a destroy-resistant request packet by the current satellite according to the location where the link failure occurred;
wherein m represents an inter-track parameter, n represents an intra-track parameter, L x+ (m, n) represents the direction degree of the current satellite (m, n) and the satellite (m+1, n) in the right neighborhood thereof, L x- (m, n) represents the direction degree of the current satellite (m, n) and the left neighbor satellite (m-1, n), L y+ (m, n) represents the direction degree of the current satellite (m, n) and the neighboring satellite (m, n+1) above it, L y- (m, n) represents the current satellite (m, n) and its backThe degree of orientation of the domain satellite (m, n-1).
2. The method for survivability of inter-satellite routes based on link prediction and region division according to claim 1, further comprising setting a virtual ID for each satellite before judging that the satellite has a periodic failure or/and a random failure, wherein the virtual ID comprises an orbit number and an in-orbit number of the satellite; and constructing a virtual topological structure according to the virtual IDs, and dividing the link relation of the satellites into inter-orbit links or/and intra-orbit links according to the virtual IDs of all the satellites.
3. The method for resisting inter-satellite routing destruction based on link prediction and area division according to claim 1, wherein determining a failure recovery period based on a rule of on-off of links, updating the failure link in advance includes determining a period of an intermittent link according to a rule of operation of satellites, slicing a system period to form discrete and limited time slices, determining a time slice corresponding to the period of the intermittent link, discarding a subsequent time slice corresponding to the period of the intermittent link when the satellites are in a previous time slice of the time slice corresponding to the period of the intermittent link, and reserving a time slice of entering a polar region of the satellites, namely the previous time slice.
4. The method as claimed in claim 1, wherein if the fault occurs in the inter-orbit link and the satellite is not in the polar region, the single-hop flooding and regional fusion of the faulty satellite to the neighboring satellite comprises if the current satellite and the links of the neighboring satellites have inter-orbit link faults, i.e. if L x+ (m, n) =0 or L x- (m, n) =0, then the current satellite performs single-hop flooding and region fusion to its own neighbor satellite; when the inter-orbit link fails, single-hop flooding is carried out, namely, the current satellite and the opposite-end satellite respectively send link state data packets to all neighbor satellites in the autonomous region; the neighbor satellite receiving the link state data packet judges whether the link failure occurs or not, if notAnalyzing a link state data packet, judging whether the analyzed inter-orbit link fault exists or not, adding the analyzed inter-orbit link fault into a link state table of the self-orbit link state packet, generating an adjacent matrix for route updating, executing a D algorithm to calculate a shortest path according to the adjacent matrix, updating a route table, detecting whether links parallel to the failed inter-orbit link exist in all satellites in an autonomous area, if so, performing area fusion, namely, performing information interaction on all satellites associated with the link, adding the other party into a waiting list of the self-orbit link state packet, and flooding according to the satellites in the waiting list when the waiting list is not empty.
5. The method for resisting damage of inter-satellite routing based on link prediction and regional division according to claim 4, wherein when the links of the current satellite and the opposite satellite, which have failed in the inter-satellite link, are restored, the current satellite and the opposite satellite respectively send updated link state data packets to all neighboring satellites in the autonomous region, and send the link state data packets to all satellites in the pending list.
6. The method as claimed in claim 1, wherein if the fault occurs in the in-orbit link and whether the satellite is in the polar region or not, the regional broadcast of the faulty satellite to all satellites in the same orbit comprises if the current satellite has an in-orbit link fault with the links of its left and right neighbors, i.e. if L y+ (m, n) =0 or L y- (m, n) =0, then regional broadcast is performed by the current satellite to all satellites in the same orbit; the current satellite and the opposite satellite with the in-orbit link fault respectively send link state data packets to all neighbor satellites in the autonomous region, the neighbor satellites receiving the link state data packets judge whether the link state data packets are in failure or not, if the link state data packets are not in failure, the link state data packets are analyzed, whether the analyzed in-orbit link failure exists or not is judged, if the link state data packets are not in failure, the link state data packets are added into a link state table of the neighbor satellites, and the neighbor satellites for route updating are generatedAnd the matrix is connected, a D algorithm is executed according to the adjacent matrix, the shortest path is calculated, and the routing table is updated.
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