Time deterministic routing method for integrated space-ground network based on time-varying graph

Abstract

The time-varying graph-based space-earth integrated network time deterministic routing method is constructed, the time-varying continuous graph model is realized, the joint description of the space-earth integrated network topology, link connectivity opportunity, link bandwidth, node cache and other multi-dimensional resource space-time attributes is realized. Related concepts such as time-varying path flow conservation and link capacity constraint are defined, and the cumulative traffic calculation rule of the link is designed, thereby supporting the path feasible flow calculation with differentiated link bandwidth. By jointly considering the transmission amount and starting time of the service, the connectivity opportunity of the link and the storage resource of the node, a shortest time delay path oriented to the service is constructed, so as to guarantee the time determinacy of the service transmission. The routing algorithm is combined with the SR technology and the TSN technology, and a time deterministic routing protocol with delay guarantee is designed, which supports time-varying topology discovery, routing design and packet forwarding on time.

Description

Technical Field

[0001] The present invention belongs to the fields of communications, computer networks and other disciplines, and specifically refers to a time-deterministic routing algorithm and protocol for a space-ground integrated network based on a time-varying graph, and more particularly to a time-deterministic routing method for a space-ground integrated network based on a time-varying graph. Background Art

[0002] The future integrated space-ground network will consist of satellites, spacecraft, ground stations, and terrestrial users. Through integrated networking and interconnection, it will support the real-time collection, transmission, and processing of massive amounts of data. Compared to existing terrestrial networks, integrated space-ground networks offer significant advantages, including global coverage, long-distance transmission, freedom from geographical constraints, and large capacity. However, due to the high-speed motion of space satellites at varying intervals, the dynamic entry and exit of space and ground equipment, and the time-varying traffic load on the network, the topology and multi-dimensional network resources of the integrated space-ground network are time-varying. This makes it difficult to establish stable end-to-end transmission paths, ensure service quality of service (QoS), and improve network resource utilization. Furthermore, communication distances between satellites and between satellites and ground nodes are long, resulting in significant link propagation delays. This long link delay hinders timely network topology discovery and maintenance, leading to outdated routes and unreachable end-to-end data transmission. Furthermore, long user access delays can also impact end-to-end latency performance. Therefore, to address these issues in integrated space-ground networks, new routing protocols and algorithms are needed to adapt to their time-varying and long-latency characteristics and improve network stability and performance.

[0003] Current Internet routing protocols include TCP / IP and the emerging Segment Routing (SR) protocol. SR divides network paths into segments and assigns SR IDs to these segments and network nodes. By sequentially arranging these Segment Routing IDs, a complete forwarding path is generated. The entire process consists of six steps: First, configure the IGP to assign SIDs to links in the network, which are used to generate link labels. This process is similar to numbering roads between cities. Second, assign SIDs to network prefixes and nodes, which are used to generate prefix and node labels. This process is similar to numbering cities or regions. Third, these generated SIDs are advertised to neighbors using the IGP. Fourth, the IGP performs path calculation. Fifth, the head node encodes the calculated path, generating labeled path information. Sixth, the head node encapsulates the path information in a data packet and forwards it hop by hop according to the MPLS forwarding mechanism.

[0004] Since there is no time attribute in the routing table of TCP / IP protocol and SR protocol, the data packet cannot be forwarded or routed according to time, which leads to difficulty in constructing deterministic routing. Meanwhile, the end-to-end path in the space-ground integrated network has time-varying characteristics, that is, the continuity of the path changes with time, which makes the lack of stable transmission path more serious, thereby further increasing the difficulty of constructing time deterministic routing. SUMMARY

[0005] The present application aims at the problems of difficult guarantee of network end-to-end delay and difficult improvement of network resource utilization caused by time-varying multi-dimensional resources and different diversified services in the space-ground integrated network, and proposes a time deterministic routing algorithm and protocol for the space-ground integrated network based on time-varying graph. A time-varying continuous graph model is constructed to represent the space-time attributes of time-varying topology, link connectivity period, node cache and other multi-dimensional resources in the space-ground integrated network. A time deterministic routing algorithm for services is proposed to construct a shortest delay path with time attribute according to link cumulative flow calculation rules, node flow conservation constraints and node cache constraints. The routing algorithm is combined with segment routing (SR) technology and time sensitive network (TSN) technology to design a time deterministic routing algorithm with delay guarantee, supporting efficient calculation of topology discovery and deterministic routing in time-varying network environment and timed forwarding protocol of packets.

[0006] In order to achieve the above effect, the time deterministic routing method for the space-ground integrated network based on time-varying graph provided by the present application comprises a plurality of nodes, the plurality of nodes are connected through links, the changing link bandwidth and connectivity opportunity are depicted in time sequence on the corresponding link, and the storage capacity of the node is also represented at the node, comprising:

[0007] Step one, a time-varying continuous graph TCG of continuous time is constructed,

[0008] TCG={V(E,T,W u,v (t),C u,v (T),Buf v ,N v (t)}|v∈V,(u,v)∈E,t∈T},

[0009] Wherein, V represents a node set, u and v represent different nodes, E represents a set of inter-satellite links and satellite-ground links, T represents a given time range, W u,v (t) represents the link bandwidth of link (u, v) at time t, C u,v (T) represents all connectivity period sets between nodes u and v in a given time range T, Buf v represents the cache size of node v, N v (t) represents the cache occupation of node v at time t.

[0010] Step two, for the time-varying path in the time-varying graph, calculate the corresponding link flow and path cumulative flow, including single-hop path flow and multi-hop path cumulative flow;

[0011] Step three, construct the time deterministic routing algorithm, including algorithm input and algorithm output two parts;

[0012] Step four, form the time deterministic routing protocol, including forming adaptive topology discovery and maintenance mechanism and multi-service time deterministic routing method based on time-varying graph, planning time-varying path meeting delay requirement for service transmission, combining the routing protocol with the segment routing v6 protocol, and based on the time triggered packet forwarding mechanism of segment routing.

[0013] Preferably, the entity nodes include physical entities such as satellites, space vehicles and ground stations.

[0014] Preferably, the step one defines the time-varying feasible flow f u,v (t) of the link (u, v) for any link (u, v) ∈ E. u,v (t) satisfies the link capacity constraint, flow conservation constraint and node buffer constraint.

[0015] Preferably, the link capacity constraint is that the feasible flow of the link (u, v) at any time t ∈ [t0, t h ] cannot exceed the link bandwidth at the corresponding time, that is,

[0016] 0 ≤ f u,v (t) ≤ W u,v (t)

[0017] At the same time, in the given time range T, the total feasible flow of the link needs to be less than the total transmission capacity of the link, that is,

[0018]

[0019] Where k is the total number of connected time periods of the link (u, v) in T = [t0, t h ], and ti and tj represent the start and end time of the ith connected time period, respectively.

[0020] Preferably, the flow conservation constraint is that for a given time range T = [t0, t h ], the total data amount flowing into any node v ∈ V is equal to the total data amount flowing out of the node, that is,

[0021]

[0022] Where f u,v (t) and f v,u ​(t) represents the feasible flow into and out of node v at time t.

[0023] Preferably, the node buffer constraint is that for any time τ∈T, the buffer occupancy N τ (t) of node v is less than or equal to the buffer size Buf v of the node, and the cumulative feasible flow of node v is described as

[0024]

[0025] Further, for any given traffic M, according to the traffic size D(M), the traffic transmission start time t start (M) and the termination time t end (M), the occupancy of the node storage and the connectivity time period of all links on the path during the end-to-end transmission of the traffic data are determined.

[0026] Preferably, the traffic calculation of the single-hop path (A, B) in step two comprises:

[0027] S101, determining the start time of the valid connectivity time period of link (A, B)

[0028] The traffic transmission start time t start (M) is compared with all link connectivity time periods C A,B (T) of link (A, B), if then if then where the set of link connectivity time periods is the start connectivity time of link (A, B) in the ith connectivity time period, is the termination connectivity time of link (A, B) in the ith connectivity time period.

[0029] S102, determining the termination time of the valid connectivity time period of link (A, B) and calculating the traffic size D(M)

[0030] The link is full during the valid connectivity time period , that is

[0031]

[0032] The termination time of the valid connectivity time period of the link is calculated by using the above formula and all valid connectivity time periods M A,B are obtained according to and , that is wherein

[0033] Preferably, the traffic computation of the multi-hop path (A, B, C) in step two above comprises:

[0034] S201, calculate the corresponding effective connectivity period of link (A, B) by using the link cumulative traffic computation rule, i.e.

[0035] S202, determine the start time of the effective connectivity period of link (B, C) The method and the determination are the same;

[0036] S203, determine the end time of the effective connectivity period of link (B, C) and calculate the path cumulative traffic according to the data flow transmitted by the effective connectivity period of link (A, B) and the related constraints, so as to obtain the feasible flow constraints of link (B, C), i.e.

[0037]

[0038] At the same time, for any time The data in the buffer of node B satisfies the following relationship

[0039]

[0040] The end time of the effective connectivity period of link (B, C) is obtained by using the same method as in 1) and the multi-hop path cumulative traffic is calculated.

[0041] Preferably, the step three above comprises:

[0042] Algorithm input: time-varying continuous graph TCG = {V (E, T, W u,v , t, C u,v (T), Buf v , N v (t)}|v∈V,(u,v)∈E,t∈T}, given service M and traffic volume D (M), service start time t start (M), service end time t end (M), source point S and destination point D of transmission;

[0043] Algorithm output: end-to-end time-varying path Path (M) from S to D, which meets the transmission requirements of M and has a deterministic delay guarantee;

[0044] ​S301. For each node v∈V, two routing parameters c[v] and p[v] are set, where c[v] represents the earliest completion time for transmitting the traffic D(M) from the source point S to the node v, and p[v] represents the previous hop node of the node v in the routing process. At the same time, they are initialized to c[v]=∞ and p[v]=-1 (-1 means that the node has no previous hop);

[0045] S302, configure node S's node cost c[S]=t start (M) and the previous hop node p[S] = -1, and add node S to the node queue set Q, that is, Q←S;

[0046] S303. Determine whether the queue Q is an empty set. If Q is an empty set, jump to S307; otherwise, execute S304.

[0047] S304: Take the node u with the lowest node cost from Q as the current path-finding node, and update the queue Q←Qu, indicating that the node u is deleted from the node queue set Q;

[0048] S305. When node u=S, i.e., the two are the same node, the effective connectivity period of all adjacent links (u, v) of node u is calculated using the service-oriented link cumulative flow calculation rule; when node u≠S, the service-oriented path cumulative flow calculation rule is used to calculate the effective link period of the link (p[u], u) and the cache capacity Buf of node u. u , calculate the effective connectivity period of all adjacent links (u, v) of node u;

[0049] S306, using the termination time of the link (u, v) to update the node cost c[v] of the adjacent node v, that is, if t uv-end <c[v],则更新c[v]=t uv-end And p[v]=u and add node v to queue Q and jump to S303;

[0050] S307. Determine the node cost of the destination point D. If c[D] = ∞, it means that there is no valid path from S to D for task M, and the algorithm terminates. Otherwise, execute S308.

[0051] S308 , starting from D, use the previous hop node p[D] in sequence to obtain the path Path(M) from S to D, and record the effective connectivity period of each link in the path.

[0052] The present invention provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the above method is implemented.

[0053] The application is directed to the routing problem of service end-to-end transmission in space-ground integrated network, and proposes a space-ground integrated network time deterministic routing algorithm and protocol based on time-varying graph to realize more efficient network resource utilization and more reliable service transmission. By constructing a time-varying continuous graph model, we can accurately depict the dynamic changes of multi-dimensional resources of space-ground integrated network at a moment, including network topology, link connectivity, link bandwidth, node cache, etc.

[0054] On this basis, the application further proposes a service-oriented time deterministic routing algorithm, which can consider factors such as transmission volume, start time, link connectivity opportunity and node storage resources according to the transmission requirements of the service, so as to construct a shortest time delay path for the service. This design can ensure that the end-to-end transmission requirements of the service in the time-varying environment are met, while effectively improving the utilization rate of network resources.

[0055] In addition, the application designs a time deterministic routing protocol with delay guarantee, which can realize dynamic discovery of topology, efficient calculation of deterministic routing and timed forwarding of data packets in the time-varying network environment with intermittent connectivity. This protocol can better adapt to the time-varying characteristics in space-ground integrated network, while meeting the time deterministic requirements of service transmission.

[0056] The advantages of the application are that the node storage resources are fully utilized, the time-varying link resource utilization rate is effectively improved, and the real-time requirements of service end-to-end transmission in the time-varying environment are guaranteed. In addition, the application can also realize more efficient routing protocol and data forwarding, further improving the network performance. At the same time, the algorithm and protocol also have good generality and scalability, low computational complexity, and can adapt to the service requirements in different scenarios. BRIEF DESCRIPTION OF DRAWINGS

[0057] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments of the application. For those skilled in the art, other drawings can also be obtained without creative labor on the premise of these drawings.

[0058] Figure 1 The flowchart of the space-ground integrated network time deterministic routing method based on time-varying graph of the application is shown;

[0059] Figure 2 The space-ground integrated network node protocol stack model in the space-ground integrated network time deterministic routing method based on time-varying graph of the application is shown;

[0060] Figure 3 The adaptive discovery and maintenance mechanism in the space-ground integrated network time deterministic routing method based on time-varying graph of the application is shown;

[0061] Figure 4 The present invention shows a time-deterministic routing method for a space-ground integrated network based on a time-varying graph. DETAILED DESCRIPTION

[0062] The features and exemplary embodiments of various aspects of the present invention will be described in detail below. In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with the accompanying drawings and Examples. It should be understood that the specific embodiments described herein are only configured to explain the present invention and are not configured to limit the present invention. For those skilled in the art, the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is merely to provide a better understanding of the present invention by illustrating examples of the present invention.

[0063] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, the elements defined by the phrase "comprising..." do not exclude the presence of other identical elements in the process, method, article, or device comprising the elements.

[0064] like Figure 1 As shown, the present invention provides an embodiment of a time-deterministic routing method for a space-ground integrated network based on a time-varying graph, comprising a plurality of nodes connected by links, wherein the changing link bandwidth and connectivity opportunities are depicted on the corresponding links in chronological order, and the storage capacity of the node is also represented at the node. The method is characterized in that:

[0065] Step 1: Construct a continuous time time-varying continuous graph TCG.

[0066] TCG={V(E,T,W u,v (t),C u,v (T),Buf v ,N v (t)}|v∈V,(u,v)∈E,t∈T},

[0067] Where V represents the node set, u and v represent different nodes, E represents the set of inter-satellite links and satellite-to-ground links, T represents the given time range, and Wu,v (t) denotes the link bandwidth of link (u, v) at time t, C u,v (T) denotes the set of all connected time periods between nodes u and v within a given time range T, Buf v denotes the buffer size of node v, N v (t) denotes the buffer occupancy of node v at time t.

[0068] Step two, for the time-varying path of end-to-end in the time-varying graph, the corresponding link flow and path cumulative flow are calculated, including single-hop path flow and multi-hop path cumulative flow.

[0069] Step three, constructing a time deterministic routing algorithm, including algorithm input and algorithm output two parts.

[0070] Step four, forming a time deterministic routing protocol, including forming an adaptive topology discovery and maintenance mechanism and a multi-service time deterministic routing method based on time-varying graph, planning a time-varying path that meets the delay requirement for service transmission, combining the routing protocol with the segment routing v6 protocol, and based on the time-triggered packet forwarding mechanism of segment routing.

[0071] In some embodiments, the entity nodes include physical entities such as satellites, space vehicles, and ground stations.

[0072] In some embodiments, step one defines the time-varying feasible flow f u,v (t) of any link (u, v) ∈ E. u,v (t) satisfies the link capacity constraint, the flow conservation constraint, and the node buffer constraint.

[0073] In some embodiments, the link capacity constraint is that the feasible flow of any time t ∈ [t0, t h ] on the link (u, v) cannot exceed the link bandwidth at the corresponding time, that is,

[0074] 0 ≤ f u,v (t) ≤ W u,v (t)

[0075] At the same time, within a given time range T, the total feasible flow of the link needs to be less than the total transmission capacity of the link, that is,

[0076]

[0077] where k is the total number of connected time periods of link (u, v) within T = [t0, t h ], and t and t

[0078] In some embodiments, the flow conservation constraint is that for a given time range T = [t0, t h ] the total amount of data flowing into any node v e V is equal to the total amount of data flowing out of the node, i.e.

[0079]

[0080] where f u,v (t) and f v,u (t) represent the feasible flow into and out of node v at time t, respectively.

[0081] In some embodiments, the node buffer constraint is that for any time t e T, the buffer occupancy N τ (t) of node v is less than or equal to the buffer Buf v of the node, and the cumulative feasible flow of node v is described as

[0082]

[0083] Further, for any given traffic M, according to the traffic size D(M), the start time t start (M) and the end time t end (M) of the traffic transmission, the occupancy of all link connectivity periods and node storage in the end-to-end transmission process of the traffic data is determined.

[0084] In some embodiments, the flow calculation of the single-hop path (A, B) in step two includes:

[0085] S101, determining the start time of the valid connectivity period of link (A, B)

[0086] The transmission start time t start (M) of the traffic is compared with all link connectivity periods C A,B (T) in link (A, B), if then if then where the set of link connectivity periods is the start connectivity time of link (A, B) in the i-th connectivity period, is the end connectivity time of link (A, B) in the i-th connectivity period.

[0087] S102, determining the end time of the valid connectivity period of link (A, B) and calculating the traffic size D(M)

[0088] Full load transmission within the valid link connectivity period ​

[0089]

[0090] The end time of the link valid connectivity period is calculated using the above formula And according to And All valid connectivity periods M are obtained A,B That is Where

[0091] In some embodiments, the traffic calculation of the multi-hop path (A, B, C) in step two includes:

[0092] S201, the corresponding valid connectivity period of link (A, B) is calculated using the link cumulative traffic calculation rule, that is

[0093] S202, the start time of the valid connectivity period of link (B, C) is determined The method is the same as determining ;

[0094] S203, the end time of the valid connectivity period of link (B, C) is determined And the path cumulative traffic is calculated, according to the valid connectivity period of link (A, B) The data flow transmitted and the related constraints can obtain the feasible flow constraints of link (B, C), that is

[0095]

[0096] At the same time, for any time The data in the buffer of node B satisfies the following relationship

[0097]

[0098] The end time of the valid connectivity period of link (B, C) is obtained using the same method as in 1) And the multi-hop path cumulative amount is calculated.

[0099] In some embodiments, step three includes:

[0100] Algorithm input: time-varying continuous graph TCG = {V (E, T, W u,v , t, C u,v (T), Buf v , N v (t)}|v∈V,(u,v)∈E,t∈T}, given service M and traffic amount D (M), service start time t start (M), service end time t end(M), the source point S and the destination point D of transmission;

[0101] algorithm output: end-to-end time-varying path Path(M) from S to D, satisfying the transmission requirement M and having deterministic delay guarantee;

[0102] S301, for each node v∈V, set 2 routing parameters c[v] and p[v], wherein c[v] represents the earliest completion time of transmitting traffic D(M) from source point S to node v, and p[v] represents the previous hop node of node v in the routing process, and simultaneously initialize c[v]=∞ and p[v]=-1 (-1 represents that the node has no previous hop);

[0103] S302, configure node cost c[S] of node S=t start (M) and previous hop p[S]=-1 of node S, and add node S into node queue set Q, i.e. Q←S;

[0104] S303, judge whether queue Q is empty set, if Q is empty set, jump to S307; otherwise, execute S304.

[0105] S304, take out node u with the minimum node cost from Q as the current routing node, and update queue Q←Q-u, indicating that delete node u from node queue set Q;

[0106] S305, when node u=S, i.e. both are the same node, use the service-oriented link cumulative flow calculation rule to calculate the effective connection period of all adjacent links (u,v) of node u; when node u≠S, use the service-oriented path cumulative flow calculation rule to calculate the effective connection period of all adjacent links (u,v) of node u according to the effective link period of link (p[u],u) and the buffer capacity Buf u of node u;

[0107] S306, update node cost c[v] of adjacent node v by using the end time of link (u,v), i.e. if t uv-end <c[v], update c[v]=t uv-end and p[v]=u, add node v into queue Q and jump to S303;

[0108] S307, judge the node cost of destination point D, if c[D]=∞, it indicates that there is no effective path from S to D for task M, terminate the algorithm; otherwise, execute S308;

[0109] S308, from D, successively use previous hop p[D] to obtain path Path(M) from S to D, and record the effective connection period of each link in the path.

[0110] The application provides an embodiment of a time-deterministic routing method for a space-ground integrated network based on a time-varying graph, comprising:

[0111] I. The space-ground integrated network is a typical time-varying network. Due to the periodic orbital motion of satellites, the network topology, link capacity, cache size of satellite nodes and motion period have predictability. Therefore, the application establishes a system model for the predictable time-varying network environment. It is assumed that all state information (including topology information, link connection state and node storage resource size) of the network within a given time range T is known. In order to accurately depict the time-varying network space-time multi-dimensional resources, all physical entities (such as satellites, space vehicles, ground stations and the like) in the space-ground integrated network are described as nodes, and the connection opportunities (such as between satellites, between satellites and ground stations) between the physical entities are described as corresponding links. At the same time, the changing link bandwidth and connection opportunity are depicted in time sequence on the corresponding link, and the storage capacity of the node is also represented at the node. Based on this, a time-varying continuous graph (TCG, time-varying continuous graph) in continuous time is constructed, that is

[0112] TCG = {V (E, T, W u,v (t), C u,v (T), Buf v , N v (t) | v ∈ V, (u, v) ∈ E, t ∈ T},

[0113] Wherein, V represents a node set, E represents a set of inter-satellite links and satellite-ground links, T represents a given time range, W u,v (t) represents the link bandwidth of the link (u, v) at time t, C u,v (T) represents a set of all connection periods between nodes u and v within the given time range T, Buf v represents the cache size of node v, N v (t) represents the cache occupation of node v at time t.

[0114] In the time-varying continuous graph, since the nodes and links have time-related constraints, it is necessary to redefine the related constraints and calculation rules of network flow in the time-varying network. First, for any link (u, v) ∈ E, f u,v (t) will be defined as the time-varying feasible flow of the link, f u,v (t) needs to satisfy the following 3 constraints.

[0115] 1) Link capacity constraint

[0116] The link capacity constraint is that the flow of any link (u, v) at any time t ∈ [t0, th ] cannot exceed the link bandwidth of the link at the time, then

[0117] 0≤f u,v (t)≤W u,v (t)

[0118] Meanwhile, the total feasible flow of the link in a given time range T should be less than the total transmission capacity of the link, i.e.

[0119]

[0120] where k is the total number of connected time periods of the link (u, v) in T = [t0, t h ], and t and t represent the start and end time of the i-th connected time period, respectively.

[0121] 2) Flow conservation constraint

[0122] For a given time range T = [t0, t h ], the total data amount flowing into any node v ∈ V is equal to the total data amount flowing out of the node, i.e.

[0123]

[0124] where f u,v (t) and f v,u (t) represent the feasible flow into and out of node v at time t, respectively.

[0125] 3) Node buffer constraint

[0126] For any time τ ∈ T, the buffer occupancy N τ (t) of node v is less than or equal to the buffer Buf v of the node, and the cumulative feasible flow of node v is described as

[0127]

[0128] In addition, for any given service M, the occupancy of the connected time periods and node storage on the path during the end-to-end transmission of the service data needs to be determined according to the service amount D(M), the service transmission start time t start (M), and the end time t start (M).

[0129] Link flow and path cumulative flow calculation

[0130] For the end-to-end time-varying path in the time-varying continuous graph, the corresponding link flow and path cumulative flow calculation rules are designed as follows:

[0131] Take single-hop path (A, B) as an example, the path traffic is calculated as follows:

[0132] Step 1: Determine the start time of the valid connectivity period of link (A, B)

[0133] Compare the transmission start time t start (M) of the service with all the link connectivity periods C A,B (T) of link (A, B), if then If then where the set of link connectivity periods is is the start connectivity time of link (A, B) in the ith connectivity period, is the end connectivity time of link (A, B) in the ith connectivity period.

[0134] Step 2: Determine the end time of the valid connectivity period of link (A, B) and calculate the service volume D (M)

[0135] In order to maximize the transmission capacity of the link, the link can be fully loaded within the valid connectivity period of the link , that is

[0136]

[0137] Then, the end time of the valid connectivity period of the link can be calculated using the above formula and all the valid connectivity periods M A,B are obtained according to and , that is where

[0138] Calculation of cumulative traffic of multi-hop path

[0139] Take two paths (A, B, C) as an example to calculate the cumulative traffic of multi-hop path.

[0140] Step 1: First, for link (A, B), the corresponding valid connectivity period can be calculated using the link cumulative traffic calculation rule, that is

[0141] Step 2: Determine the start time of the valid connectivity period of link (B, C) The method is the same as that for determining the start time of the valid connectivity period of link (A, B).

[0142] Step 3: Determine the end time of the valid communication period of link (B, C) and calculate the cumulative flow of the path. According to the valid communication period of link (A, B) the data flow transmitted and the related constraints, the feasible flow constraints of link (B, C) can be obtained, that is,

[0143]

[0144] At the same time, for any time The data cached by node B satisfies the following relationship

[0145]

[0146] The same method as in 1) is used to obtain the end time of the valid communication period of link (B, C) and calculate the cumulative flow of the multi-hop path.

[0147] Time deterministic routing algorithm

[0148] Algorithm input: Time-varying continuous graph TCG = {V (E, T, W u,v , t, C u,v (T), Buf v , N v (t)}|v∈V,(u,v)∈E,t∈T}, given service M and traffic volume D(M), service start time t start (M), service end time t end (M), source point S and destination point D of transmission.

[0149] Algorithm output: end-to-end time-varying path Path(M) from S to D, which meets the transmission requirements of M and has deterministic delay guarantee.

[0150] Step 1: Set two routing parameters c[v] and p[v] for each node v∈V, where c[v] represents the earliest completion time of transmitting traffic volume D(M) from source point S to node v, and p[v] represents the previous hop node of node v in the routing process. Initialize V[v] = ∞ and p[v] = -1 (-1 represents that the node has no previous hop).

[0151] Step 2: Configure node cost c[S] = t start (M) and previous hop node p[S] = -1 for node S, and add node S to node queue Q, that is, Q←S.

[0152] Step 3: Determine whether the queue Q is empty, if Q is empty, jump to Step 7; otherwise, execute Step 4.

[0153] Step 4: Take the node u with the lowest node cost from Q as the current path-finding node, and update the queue Q←Qu, indicating that node u is deleted from the node queue set Q.

[0154] Step 5: When node u = S, i.e., the two are the same node, the service-oriented link cumulative flow calculation rule is used to calculate the effective connectivity period of all adjacent links (u, v) of node u; when node u ≠ S, the service-oriented path cumulative flow calculation rule is used to calculate the effective link period of the link (p[u], u) and the buffering capacity Buf of node u. u , calculate the effective connectivity period of all adjacent links (u, v) of node u.

[0155] Step 6: Use the termination time of the link (u, v) to update the node cost c[v] of the adjacent node v, that is, if t uv-end <c[v],则更新c[v]=t uv-end And p[v] = u and add node v to queue Q and jump to Step 3.

[0156] Step 7: Determine the node cost of the destination point D. If c[D] = ∞, it means that there is no valid path from S to D for task M, and the algorithm terminates; otherwise, execute Step 8.

[0157] Step 8: Starting from D, use the previous hop node p[D] in turn to obtain the path Path(M) from S to D, and record the effective connectivity period of each link in the path.

[0158] Time-deterministic routing protocol

[0159] The time-deterministic routing algorithm based on the time-varying graph can plan time-varying paths that meet the transmission requirements for different services. However, in order to ensure the time determinism of service transmission, corresponding protocols are required as support. Therefore, the present invention proposes a time-deterministic routing protocol and protocol stack model for the time-varying environment of the integrated space-ground network, such as Figure 2 As shown in the figure. This model expands the network layer protocol based on the traditional TCP / IP protocol stack and adds a time-deterministic routing protocol. This includes an adaptive topology discovery and maintenance mechanism and a multi-service time-deterministic routing algorithm based on a time-varying graph. This allows for planning time-varying paths for service transmission that meet latency requirements. Furthermore, to provide precise transmission and hosting control for each type of service, the present invention combines the routing protocol with the Segment Routing v6 protocol and proposes a time-triggered packet forwarding mechanism based on segment routing. This allows for efficient transmission of different services along different explicit paths, ensuring time determinism.

[0160] 1) Automatic topology discovery and maintenance

[0161] Topology discovery is the basis of routing computation, so timely and accurate acquisition of network topology and available resources is the key to time deterministic routing construction. The mobility of nodes, the sharing of resources and the dynamic joining and leaving of nodes in the integrated space information network lead to frequent changes in network topology, and the traditional topology discovery mechanism based on fixed period is facing problems. The shorter the topology discovery period, the higher the accuracy of topology information, but the signaling load is heavy, which restricts the performance of routing algorithm. If the topology discovery period is too long, the topology changes caused by sudden situations are not discovered in time, which is easy to produce outdated routing, leading to packet loss, and the additional overhead of re-routing. Based on this, considering that the topology changes of the integrated space information network have a certain predictability, the periodic topology discovery is combined with the topology discovery based on topology prediction and the topology discovery based on active detection, and an adaptive topology discovery and maintenance mechanism is proposed to ensure timely and accurate topology information while reducing signaling load. As shown in FIG. 3(1), the topology is detected by sending probe packets with a period of time T. If the topology changes are predicted according to the node's running trajectory, speed and time, etc., the probe packets are sent at the time of link disconnection or connection, and the topology is detected and maintained with a period greater than T at other times, which can effectively reduce the overhead, as shown in FIG. 3(2). For the topology changes that are difficult to predict due to faults and other reasons, the probe packets are sent actively to ensure the timeliness of the topology information, as shown in FIG. 3(3).

[0162] Through the adaptive topology discovery and maintenance mechanism, the topology and available resources of the integrated space information network can be dynamically acquired as the input of the multi-service time deterministic routing algorithm to calculate the time-varying path with deterministic delay and convert it into a routing table with time attributes, i.e., containing the start and end time of each hop transmission. The relationship between the modules in the protocol is shown in FIG. 4. Figure 4

[0163] 2) Time triggered packet forwarding mechanism

[0164] This embodiment considers the co-transmission of periodic and aperiodic data in the same network in TSN technology, divides the service packets into time deterministic service packets and ordinary service packets (ordinary service without time delay guarantee), and realizes packet forwarding by using time trigger mechanism.

[0165] ​In particular, for packets of time-deterministic services, this embodiment further integrates segmented routing technology to route and forward packets. Specifically, based on the constructed time-varying routing table, routing information is added to the packet header. In addition, in order to accurately control the transmission of packets, the start and end times of forwarding are also added. When a network node forwards a packet, it will first identify the routing information in the packet header, obtain the next hop node, and execute the forwarding process triggered by time until the packet is delivered to the destination node. If hosting is required at the node, a timer is set according to the routing table information, and data is transmitted after the timer expires. For ordinary services that do not have strict delay guarantee requirements, without affecting the transmission of time-deterministic services, the storage-hosting-forwarding of packets is realized through the IPv6 process in accordance with the uniformly calculated routing table.

[0166] Compared to existing technologies, this paper addresses the routing problem of end-to-end service transmission in a space-ground integrated network by proposing a time-deterministic routing algorithm and protocol based on a time-varying graph. This approach enables more efficient network resource utilization and more reliable service transmission. By constructing a time-varying continuous graph model, we can accurately characterize the dynamic changes in the multi-dimensional resources of the space-ground integrated network, including network topology, link connectivity, link bandwidth, node cache, and more.

[0167] Building on this foundation, the present invention further proposes a service-oriented time-deterministic routing algorithm. This algorithm comprehensively considers factors such as transmission volume, start time, link connectivity opportunities, and node storage resources based on the service's transmission requirements, thereby constructing a service-oriented path with the shortest latency. This design ensures that the end-to-end transmission requirements of services in time-varying environments are met while effectively improving network resource utilization.

[0168] Furthermore, the present invention designs a time-deterministic routing protocol with guaranteed latency. This protocol enables dynamic topology discovery, efficient deterministic routing calculation, and timed forwarding of data packets in intermittently connected, time-varying network environments. This protocol better adapts to the time-varying nature of integrated ground-ground networks while meeting the time-deterministic requirements of service transmission.

[0169] The advantages of this invention are that it fully utilizes node storage resources, effectively improving the utilization rate of time-varying link resources, thereby ensuring the real-time requirements of end-to-end service transmission in time-varying environments. Furthermore, this invention enables more efficient routing protocols and data forwarding, further improving network performance. Furthermore, the algorithm and protocol exhibit high versatility and scalability, with low computational complexity, and can adapt to service needs in diverse scenarios.

[0170] For the sake of description, the above-described apparatus is described with various units in function to describe the embodiment. Of course, the units can be implemented by one or more software and / or hardware in the embodiment of the present application.

[0171] Those skilled in the art will appreciate that embodiments of the present application can be readily used as a method, a system or a computer program product. Accordingly, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application can take the form of a computer program product on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs, optical storage devices, etc.) embodying computer-readable program code.

[0172] The present application is described with reference to the flowchart and / or block diagram of the method, apparatus (system) and computer program product according to the embodiments of the present application. It will be understood that each block of the flowchart and / or block diagram, and combinations of blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processing unit or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart and / or block diagram block or blocks. Figure 1 one or more functions specified in the flowchart and / or block diagram block or blocks. Figure 1 one or more functions specified in the flowchart and / or block diagram block or blocks.

[0173] The present application can be described in the general context of computer- executable instructions, such as program modules, being executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. The present application can also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules can be located in local and remote computer storage media including memory storage devices.

[0174] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the flowchart and / or block diagram block or blocks. Figure 1 one or more functions specified in the flowchart and / or block diagram block or blocks. Figure 1 one or more functions specified in the flowchart and / or block diagram block or blocks.

[0175] These computer program instructions can also be loaded into a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 Figure 1

[0176] In one typical configuration, the computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0177] The memory can include non-persistent memory and / or volatile memory, such as random access memory (RAM) about which the processor can execute instructions. The memory can also include non-volatile memory, such as read only memory (ROM), electrically programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), programmable read only memory (PROM), erasable programmable read only memory (EPROM), flash memory, or a combination of non-volatile memories in different types. The memory is an example of computer readable storage media.

[0178] Computer readable media includes permanent and non-permanent, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read only memory (ROM), electrically programmable read only memory (EEPROM), flash memory or other memory technology, compact disc read only memory (CD-ROM), digital versatile disc (DVD), or other optical storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information accessible to computing devices. According to the definition herein, computer readable media does not include transitory media such as modulated data signals and carrier waves.

[0179] It should also be noted that the terms "comprising", "comprises", "including", "includes" or any other variation thereof are intended to cover a non-exclusive inclusion, such that a process, method, article or apparatus that comprises a list of elements does not include only those elements recited, but can also include other elements not expressly listed or inherent to such process, method, article or apparatus. Without further limitation, an element preceded by "comprises a" does not, without more constraints, foreclose the existence of additional identical elements in the process, method, article or apparatus that includes the recited element.

[0180] ​​The various embodiments in the specification are described in progressive manner, and the same or similar parts among the various embodiments can be mutually referred to, and each embodiment focuses on the difference from other embodiments. In particular, for the system embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the part of the method embodiments.

[0181] The above only describes the embodiments of the present application and is not intended to limit the present application. The present application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the scope of claims of the present application.

Claims

1. A time-deterministic routing method for a space-ground integrated network based on a time-varying graph, comprising a plurality of nodes connected by links, wherein the changing link bandwidth and connectivity opportunities are depicted on the corresponding links in chronological order, and the storage capacity of the nodes is also represented at the nodes, characterized by: The method comprises: Step 1: Construct a continuous time time-varying continuous graph TCG. TCG={V(E,T,W u,v (t),C u,v (T),Buf v ,N v (t)}|v∈V,(u,v)∈E,t∈T}, Where V represents the node set, u and v represent different nodes, E represents the set of inter-satellite links and satellite-to-ground links, T represents the given time range, and W u,v (t) represents the link bandwidth of the link (u, v) at time t, C u,v (T) represents the set of all connected time periods between nodes u and v within a given time range T, Buf v represents the cache size of node v, N v (t) represents the cache occupancy of node v at time t; Step 2: For the end-to-end time-varying paths in the time-varying continuous graph, calculate the corresponding link traffic and path cumulative traffic, including single-hop path traffic and multi-hop path cumulative traffic; Step 3: Construct a time-deterministic routing algorithm, including two parts: algorithm input and algorithm output. Time-varying continuous graph TCG={V(E,T,W u,v ,t,C u,v (T),Buf v ,N v (t)}|v∈V,(u,v)∈E,t∈T}, given the service M and service volume D(M), the service start time t start (M), business end time t end (M), the source point S and destination point D of the transmission; The algorithm outputs: an end-to-end time-varying path Path(M) from S to D that meets the transmission requirements of M and has deterministic latency guarantee; S301. For each node v∈V, two routing parameters c[v] and p[v] are set, where c[v] represents the earliest completion time for transmitting the traffic D(M) from the source point S to the node v, and p[v] represents the previous hop node of the node v in the routing process. At the same time, they are initialized to c[v]=∞ and p[v]=-1, where -1 indicates that the node has no previous hop. S302, configure node S's node cost c[S]=t start (M) and the previous hop node p[S] = -1, and add node S to the node queue set Q, that is, Q←S; S303, determine whether the queue Q is an empty set, if Q is an empty set, jump to S307; otherwise, execute S304; S304: Take the node u with the lowest node cost from Q as the current path-finding node, and update the queue Q←Qu, indicating that the node u is deleted from the node queue set Q; S305. When node u=S, i.e., the two are the same node, the effective connectivity period of all adjacent links (u, v) of node u is calculated using the service-oriented link cumulative flow calculation rule; when node u≠S, the service-oriented path cumulative flow calculation rule is used to calculate the effective link period of the link (p[u], u) and the cache capacity Buf of node u. u , calculate the effective connectivity period of all adjacent links (u, v) of node u; S306. Update the node cost c[v] of the adjacent node v using the termination time of the link (u, v). That is, if t uv-end < c[v], then update c[v] = t uv-end and p[v] = u, add the node v to the queue Q, and jump to S303; S307. Determine the node cost of the destination point D. If c[D] = ∞, it means that there is no valid path from S to D for task M, and the algorithm terminates. Otherwise, execute S308. S308. Starting from D, use the previous hop node p[D] in sequence to obtain the path Path(M) from S to D, and record the effective connectivity period of each link in the path; Step 4: Form a time-deterministic routing protocol, including forming an adaptive topology discovery and maintenance mechanism and a multi-service time-deterministic routing method based on a time-varying graph, planning a time-varying path that meets the latency requirements for service transmission, combining the routing protocol with the Segment Routing v6 protocol, and a time-triggered packet forwarding mechanism based on segment routing.

2. The time-deterministic routing method for a space-ground integrated network based on a time-varying graph according to claim 1 is characterized in that The nodes include satellites, spacecraft and ground stations.

3. The time-deterministic routing method for a space-ground integrated network based on a time-varying graph according to claim 1 or 2, characterized in that In step 1, for any link (u, v)∈E, define the time-varying feasible flow f of the link u,v (t), f u,v (t) Satisfy link capacity constraints, flow conservation constraints, and node cache constraints.

4. The time-deterministic routing method for a space-ground integrated network based on a time-varying graph according to claim 3 is characterized in that The link capacity constraint is that at any time t∈[t0,t h ] cannot exceed the link bandwidth of the link at the corresponding time, then 0≤f u,v (t)≤W u,v (t) At the same time, within a given time range T, the total feasible flow of the link must be less than the total transmission capacity of the link, that is, where k is T=[t0,t h ]The total number of connected periods of the link (u, v) within They represent the start and end time of the i-th connected period respectively.

5. The time-deterministic routing method for space-ground integrated network based on time-varying graph according to claim 3 is characterized in that The flow conservation constraint is that for a given time range T = [t0, t h ], the total amount of data flowing into any node v∈V is equal to the total amount of data flowing out of the node, that is, where f u,v (t) and f v,u (t) represent the feasible flows into and out of node v at time t, respectively.

6. The time-deterministic routing method for space-ground integrated network based on time-varying graph according to claim 3 is characterized in that The node cache constraint is that for any time τ∈T, the cache occupancy of node v is N τ (t) is less than or equal to the node's cache Buf v , and the cumulative feasible flow of node v is described as In addition, for any given service M, according to the service volume D(M), service transmission start time t start (M) and the termination time t end (M) Determine the usage of all link connectivity periods and node storage on the path during end-to-end transmission of service data.

7. The time-deterministic routing method for a space-ground integrated network based on a time-varying graph according to claim 1 or 2, characterized in that: The flow calculation of the single-hop path (A, B) in step 2 includes: S101. Determine the start time of the effective connection period of link (A, B) The transmission start time of the service t start (M) is connected to all links in link (A, B) for period C A,B (T) for comparison, if but like but The link connectivity period set is the starting connection time of the link (A, B) in the i-th connection period, is the termination time of the link (A, B) in the i-th connectivity period; S102: Determine the end time of the effective connection period of link (A, B) And calculate the business volume D(M) During the link effective connection period Internal full load transmission, that is Use the above formula to calculate the end time of the link effective connection period And according to and Get all valid connected periods M A,B ,Right now in 8. The time-deterministic routing method for a space-ground integrated network based on a time-varying graph according to claim 1 or 2, characterized in that The flow calculation of the multi-hop path (A, B, C) in step 2 includes: S201. Calculate the corresponding effective connection period for the link (A, B) using the link cumulative flow calculation rule, that is, S202: Determine the start time of the effective connection period of link (B, C) Methods and determination same; S203: Determine the end time of the effective connection period of link (B, C) And calculate the cumulative flow of the path, according to the effective connectivity period of link (A, B) The transmitted data flow and related constraints can be used to obtain the feasible flow constraints of link (B, C), that is, At any time Node B caches data that satisfies the following relationship Use the same method as in 1) to obtain the end time of the effective connection period of link (B, C) And calculate the multi-hop path accumulation.

9. A computer-readable storage medium having a computer program stored thereon, wherein when the program is executed by a processor, the method according to any one of claims 1 to 8 is implemented.

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