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

Abstract

According to the space-ground integrated network time deterministic routing method based on the time-varying graph provided by the invention, through constructing the time-varying continuous graph model, joint description of multi-dimensional resource space-time attributes such as space-ground integrated network topology, link connection opportunities, link bandwidths, node caches and the like is realized. Related concepts of time-varying path flow conservation, link capacity constraint and the like are also defined, and a cumulative flow calculation rule of a link is designed, so that path feasible flow calculation with differentiated link bandwidths is supported. The service-oriented shortest delay path is constructed by jointly considering the transmission quantity and the starting time of the service, the connection opportunity of the link and the storage resource of the node, so that the time certainty of service transmission is guaranteed. The provided routing algorithm is combined with the SR technology and the TSN technology, a time deterministic routing protocol with time delay guarantee is designed, and the protocol supports time-varying topology discovery, routing design and on-time forwarding of packets.

Description

Technical Field

[0001] The present invention belongs to the fields of communication, computer network 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] In the future, the integrated space-ground network will be composed of satellites, spacecraft, ground stations and ground users. Through integrated networking and interconnection, it supports real-time collection, transmission and processing of massive data. Compared with the existing ground network, the integrated space-ground network has significant advantages such as global coverage, long-distance transmission, no geographical restrictions, and large capacity. However, due to the high-speed movement of space satellites in different periods, the dynamic addition and exit of space and ground equipment, and the dynamic change of network-borne business load over time, the topology and multi-dimensional network resources of the integrated space-ground network are time-varying, making it difficult to build a stable end-to-end transmission path for the network, guarantee the service quality (QoS), and improve the utilization rate of network resources. In addition, the communication distance between satellites and between satellites and ground nodes is long, and the link propagation delay is large. The long delay characteristics of the link cause the network topology to be discovered and maintained in a timely manner, resulting in the generation of outdated routes, resulting in end-to-end data transmission unreachable, and the long delay of user access will also affect the end-to-end delay performance guarantee. Therefore, in response to these problems in the integrated space-ground network, it is necessary to study new routing protocols and algorithms to adapt to its time-varying and long delay characteristics and improve the stability and performance of the network.

[0003] The current Internet routing protocols include TCP / IP and the emerging segment routing (SR) protocol. The segment routing protocol (SR) divides the network path into small segments, and then assigns SR IDs to these segments and network nodes. By arranging these Segment Routing IDs in order, a complete forwarding path can be generated. The whole process is specifically divided into six steps: the first step is to configure IGP to assign SIDs to links in the network for generating link labels. This process is equivalent to numbering roads between cities. The second step is to assign SIDs to network prefixes and nodes for generating prefix labels and node labels. This process is equivalent to numbering cities or regions. The third step is to use IGP to notify the generated SIDs to neighbors. The fourth step is that IGP performs path calculation. The fifth step is that the head node encodes the calculated path and generates labeled path information. The sixth step is that the head node encapsulates the path information in the data message 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, it is impossible to forward or route data packets according to time, which makes it difficult to build deterministic routing. At the same time, the end-to-end path in the integrated space-ground network has time-varying characteristics, that is, the continuity of the path will change with time, which makes the lack of stable transmission paths more serious, thus further increasing the difficulty of building time-deterministic routing. Summary of the invention

[0005] Aiming at the problems that the time-varying multi-dimensional resources and differentiated and diversified services of the space-ground integrated network make it difficult to guarantee the end-to-end delay of the network and improve the utilization rate of network resources, the present invention proposes a time-deterministic routing algorithm and protocol for the space-ground integrated network based on a time-varying graph. A time-varying continuous graph model is constructed to characterize the spatiotemporal attributes of multi-dimensional resources such as the time-varying topology, link connectivity period, and node cache of the space-ground integrated network; a service-oriented time-deterministic routing algorithm is proposed, and the shortest delay path with time attributes is constructed according to the link cumulative flow calculation rules, node flow conservation constraints, and node cache constraints; the proposed routing algorithm is combined with the segment routing (SR) technology and the time-sensitive network (TSN) technology to design a time-deterministic routing algorithm with delay guarantee, which supports topology discovery in a time-varying network environment, efficient calculation of deterministic routing, and timed forwarding protocol of packets.

[0006] In order to achieve the above effect, the time-deterministic routing method of the space-ground integrated network based on the time-varying graph provided by the present invention includes multiple nodes, the multiple nodes are connected by links, the changing link bandwidth and connection opportunities are depicted on the corresponding links in time sequence, and the storage capacity of the node is also characterized at the node, including:

[0007] Step 1: Construct a continuous-time time-varying continuous graph TCG.

[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] 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 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;

[0010] Step 2: for the end-to-end time-varying path in the time-varying continuous graph, calculate the corresponding link flow and path cumulative flow, including single-hop path flow and multi-hop path cumulative flow;

[0011] Step 3: Construct a time-deterministic routing algorithm, including algorithm input and algorithm output;

[0012] 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.

[0013] Preferably, the above-mentioned physical nodes include physical entities such as satellites, spacecraft and ground stations.

[0014] Preferably, in the above step 1, for any link (u, v)∈E, a time-varying feasible flow f of the link is defined u,v (t), f u,v (t) Satisfy link capacity constraints, flow conservation constraints, and node cache constraints.

[0015] Preferably, 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

[0016] 0≤f u,v (t)≤W u,v (t)

[0017] 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,

[0018]

[0019] where k is T=[t0,t h ]The total number of connected time periods of the link (u, v) within They represent the start and end time of the i-th connected period respectively.

[0020] Preferably, the above 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,

[0021]

[0022] where f u,v (t) and f v,u(t) represent the feasible flows into and out of node v at time t, respectively.

[0023] Preferably, 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

[0024]

[0025] In addition, for any given service M, according to the service volume D(M), the service transmission start time t start (M) and the termination time t end (M) Determine the occupancy of all link connectivity periods and node storage on the path during end-to-end transmission of business data.

[0026] Preferably, the flow calculation of the single-hop path (A, B) in the above step 2 includes:

[0027] S101: Determine the start time of the effective connection period of link (A, B)

[0028] The transmission start time of the service is 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 connection period.

[0029] S102: Determine the end time of the effective connection period of link (A, B) And calculate the business volume D(M)

[0030] During the link effective connection period Internal full load transmission, that is

[0031]

[0032] Use the above formula to calculate the end time of the link effective connection period And according to and Get all the valid connection periods M A,B ,Right now in

[0033] Preferably, the flow calculation of the multi-hop path (A, B, C) in the above step 2 includes:

[0034] S201. For link (A, B), calculate the corresponding effective connection period using the link cumulative flow calculation rule, that is,

[0035] S202: Determine the start time of the effective connection period of link (B, C) Methods and determination same;

[0036] 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 connection period of link (A, B) The transmitted data flow and related constraints can obtain the feasible flow constraints of link (B, C), that is,

[0037]

[0038] At any time Node B caches data that satisfies the following relationship

[0039]

[0040] Use the same method as in 1) to get the end time of the effective connection period of link (B, C) And calculate the multi-hop path accumulation.

[0041] Preferably, the above step three includes:

[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 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 the destination point D of the transmission;

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

[0044] S301. For each node v ∈ V, two routing parameters c[v] and p[v] are set. Among them, c[v] represents the earliest completion time for transmitting traffic D(M) from the source point S to node v, and p[v] represents the previous-hop node of node v during the routing process. At the same time, initialize them as c[v] = ∞ and p[v] = -1 (-1 indicates that this node has no previous hop).

[0045] S302. Configure the node cost of node S as 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 out the node u with the smallest node cost from Q as the current routing node, and at the same time update the queue Q ← Q - u, indicating that node u is deleted from the node queue set Q;

[0048] S305. When node u = S, that is, the two are the same node, use the traffic-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 traffic-oriented path cumulative flow calculation rule, according to the effective link period of link (p[u], u) and the buffer capacity Buf u of node u, calculate the effective connection period of all adjacent links (u, v) of node u;

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

[0050] S307. Judge the size of the node cost of the destination point D. If c[D] = ∞, it means that there is no effective path from S to D for task M, and the algorithm is terminated; otherwise, execute S308;

[0051] S308. Starting from D, successively use the previous-hop node p[D] to obtain the path Path(M) from S to D, and record the effective connection 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] Aiming at the routing problem of end-to-end transmission of services in the space-ground integrated network, this paper proposes a space-ground integrated network time deterministic routing algorithm and protocol based on time-varying graph to achieve 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 of multi-dimensional resources in the space-ground integrated network at all times, including network topology, link connectivity, link bandwidth, node cache, etc.

[0054] On this basis, the present invention further proposes a service-oriented time-deterministic routing algorithm, which can build the shortest latency path for the service based on the transmission requirements of the service, taking into account factors such as transmission volume, start time, link connectivity opportunities, and node storage resources. This design can ensure that the end-to-end transmission requirements of the service in a time-varying environment are met, while effectively improving the utilization of network resources.

[0055] In addition, the present invention 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 a time-varying network environment with intermittent connectivity. This protocol can better adapt to the time-varying characteristics of the integrated space-ground network and meet the time-deterministic requirements of service transmission.

[0056] The advantages of the present invention are: fully utilizing node storage resources, effectively improving the utilization rate of time-varying link resources, thereby ensuring the real-time requirements of end-to-end transmission of services in a time-varying environment. In addition, the present invention can also achieve more efficient routing protocols and data forwarding, further improving network performance. At the same time, the algorithm and protocol also have good versatility and scalability, low computational complexity, and can adapt to business needs in different scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the technical solution of the embodiment of the present invention, the following briefly introduces the drawings required for use in the embodiment of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0058] Figure 1 A schematic diagram of a flow chart of a time-deterministic routing method for a space-ground integrated network based on a time-varying graph of the present invention is shown;

[0059] Figure 2 A schematic diagram of a protocol stack model of a space-ground integrated network node in a space-ground integrated network time deterministic routing method based on a time-varying graph of the present invention is shown;

[0060] Figure 3 A schematic diagram of an adaptive discovery and maintenance mechanism in a time-deterministic routing method for a space-ground integrated network based on a time-varying graph of the present invention 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 purpose, technical solutions and advantages of the present invention clearer, 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 only to provide a better understanding of the present invention by illustrating examples of the present invention.

[0063] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "include..." do not exclude the presence of other identical elements in the process, method, article or device including 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, wherein the plurality of nodes are connected by links, and the changing link bandwidth and connectivity opportunities are depicted on the corresponding links in time sequence, and the storage capacity of the node is also characterized at the node, and the method comprises:

[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) represents the link bandwidth of 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;

[0068] Step 2: for the end-to-end time-varying path in the time-varying continuous graph, calculate the corresponding link flow and path cumulative flow, including single-hop path flow and multi-hop path cumulative flow;

[0069] Step 3: Construct a time-deterministic routing algorithm, including algorithm input and algorithm output;

[0070] 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.

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

[0072] In some embodiments, step 1 defines a time-varying feasible flow f for any link (u, v)∈E for the link: u,v (t), f u,v (t) Satisfy link capacity constraints, flow conservation constraints, and node cache constraints.

[0073] In some embodiments, 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

[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 must be less than the total transmission capacity of the link, that is,

[0076]

[0077] where k is T=[t0,t h ]The total number of connected time periods of the link (u, v) within They represent the start and end time of the i-th connected period respectively.

[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∈V is equal to the total amount of data flowing out of the node, that is,

[0079]

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

[0081] In some embodiments, 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

[0082]

[0083] In addition, for any given service M, according to the service volume D(M), the service transmission start time t start (M) and the termination time t end (M) Determine the occupancy of all link connectivity periods and node storage on the path during end-to-end transmission of business data.

[0084] In some embodiments, the flow calculation of the single-hop path (A, B) in step 2 includes:

[0085] S101: Determine the start time of the effective connection period of link (A, B)

[0086] The transmission start time of the service is 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 connection period.

[0087] S102: Determine the end time of the effective connection period of link (A, B) And calculate the business volume D(M)

[0088] During the link effective connection period Internal full load transmission, that is

[0089]

[0090] Use the above formula to calculate the end time of the link effective connection period And according to and Get all valid connected time periods M A,B ,Right now in

[0091] In some embodiments, the flow calculation of the multi-hop path (A, B, C) in step 2 includes:

[0092] S201. For link (A, B), calculate the corresponding effective connection period using the link cumulative flow calculation rule, that is,

[0093] S202: Determine the start time of the effective connection period of link (B, C) Methods and determination same;

[0094] 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 connection period of link (A, B) The transmitted data flow and related constraints can obtain the feasible flow constraints of link (B, C), that is,

[0095]

[0096] At any time Node B caches data that satisfies the following relationship

[0097]

[0098] Use the same method as in 1) to get the end time of the effective connection period of link (B, C) And calculate the multi-hop path accumulation.

[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 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 the destination point D of the transmission;

[0101] Algorithm output: The end-to-end time-varying path Path(M) from S to D, which meets the transmission requirements of M and has deterministic delay guarantee;

[0102] S301. For each node v ∈ V, two routing parameters c[v] and p[v] are set. Among them, c[v] represents the earliest completion time for transmitting the traffic volume D(M) from the source point S to the node v, and p[v] represents the previous hop node of the node v during the routing process. At the same time, initialize them as c[v] = ∞ and p[v] = -1 (-1 indicates that the node has no previous hop);

[0103] S302. Configure the node cost of node S as c[S] = t start (M) and the previous hop node p[S] = -1, and add the node S to the node queue set Q, that is, Q ← S;

[0104] S303. Determine whether the queue Q is an empty set. If Q is an empty set, jump to S307; otherwise, execute S304.

[0105] S304. Take the node u with the smallest node cost from Q as the current path-finding node, and at the same time update the queue Q ← Q - u, indicating that the node u is deleted from the node queue set Q;

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

[0107] 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 and add the node v to the queue Q and jump to S303;

[0108] S307. Determine the size of the node cost of the destination point D. If c[D] = ∞, it means that there is no effective path from S to D for the task M, and the algorithm terminates; otherwise, execute S308;

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

[0110] 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:

[0111] 1. The integrated space-ground network is a typical time-varying network. Due to the periodic orbiting motion of satellites, the changes in network topology, link capacity, cache size of satellite nodes, and motion cycle are all predictable. Therefore, the present invention establishes a system model for a predictable time-varying network environment. It is assumed that within a given time range T, all state information of the network (including topology information, link connectivity status, and node storage resource size, etc.) is known. In order to accurately characterize the spatiotemporal multi-dimensional resources of the time-varying network, the present invention describes all physical entities in the integrated space-ground network (such as satellites, spacecraft, ground stations, etc.) as nodes, and the connectivity opportunities between physical entities (such as between satellites and satellites, between satellites and ground stations) are described as corresponding links. At the same time, 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 characterized at the node. Based on this, a continuous-time time-varying continuous graph (TCG) 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] Where V represents the node set, 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 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.

[0114] In a time-varying continuous graph, since both nodes and links have time-related constraints, it is necessary to redefine the relevant constraints and calculation rules of network flows in time-varying networks. First, for any link (u, v) ∈ E, f u,v (t) will be defined as the time-varying feasible flow on the link, f u,v (t) The following three constraints must be met.

[0115] 1) Link capacity constraints

[0116] At any time t∈[t0,th ] cannot exceed the link bandwidth of the link at the corresponding time, then

[0117] 0≤f u,v (t)≤W u,v (t)

[0118] 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,

[0119]

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

[0121] 2) Flow conservation constraints

[0122] 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,

[0123]

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

[0125] 3) Node cache constraints

[0126] 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

[0127]

[0128] In addition, for any given service M, it is necessary to calculate the service volume D(M) and the service transmission start time t start (M) and the end time t start (M) Determine the occupancy of all link connectivity periods and node storage on the path during end-to-end transmission of business data.

[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] Taking a single-hop path (A, B) as an example, the path flow is calculated as follows:

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

[0133] The transmission start time of the service is 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 connection period.

[0134] Step 2: Determine the end time of the effective connection period of link (A, B) And calculate the business volume D(M)

[0135] In order to maximize the transmission capacity of the link, Internal full load transmission, that is

[0136]

[0137] Then, the above formula can be used to calculate the end time of the link effective connection period And according to and Get all valid connected time periods M A,B ,Right now in

[0138] Calculation of cumulative flow on multi-hop paths

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

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

[0141] Step 2: Determine the start time of the effective connectivity period of link (B, C) Methods and determination same;

[0142] Step 3: 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 connection period of link (A, B) The transmitted data flow and related constraints can obtain the feasible flow constraints of link (B, C), that is,

[0143]

[0144] At any time Node B caches data that satisfies the following relationship

[0145]

[0146] Use the same method as in 1) to get the end time of the effective connection period of link (B, C) And calculate the multi-hop path accumulation.

[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 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.

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

[0150] Step 1: For each node v∈V, two routing parameters c[v] and p[v] are set, where c[v] represents the earliest completion time of 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, it is initialized to V[v]=∞, p[v]=-1 (-1 means that the node has no previous hop).

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

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

[0153] Step 4: Take the node u with the minimum node cost from Q as the current routing node, and at the same time update the queue Q←Q - u, indicating that the node u is deleted from the node queue set Q.

[0154] Step 5: When the node u = S, that is, when the two are the same node, use the service-oriented link cumulative traffic calculation rule to calculate the effective connection period of all adjacent links (u, v) of the node u; when the node u ≠ S, use the service-oriented path cumulative traffic calculation rule, according to the effective link period of the link (p[u], u) and the buffer capacity Buf u of the node u, calculate the effective connection period of all adjacent links (u, v) of the 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], then update c[v] = t uv-end and p[v] = u and add the node v to the queue Q and jump to Step 3.

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

[0157] Step 8: Starting from D, sequentially use the previous-hop node p[D] to obtain the path Path(M) from S to D, and record the effective connection 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, a corresponding protocol is also required as support. Therefore, the present invention proposes a time-deterministic routing protocol and protocol stack model for the time-varying environment of the space-ground integrated network, as Figure 2 shown. This model extends the network layer protocol on the basis of the traditional TCP / IP protocol stack, adding a time-deterministic routing protocol, including an adaptive topology discovery and maintenance mechanism and a multi-service time-deterministic routing algorithm based on the time-varying graph, and plans time-varying paths that meet the delay requirements for service transmission. In addition, in order to accurately transmit and manage and control 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 to realize the efficient transmission of different services according to different explicit paths and ensure time determinism.

[0160] 1) Topology Automatic Discovery and Maintenance

[0161] Topology discovery is the basis of routing calculation. Therefore, timely and accurate acquisition of network topology and available resources is the key to building time-deterministic routing. The mobility of nodes, resource sharing, and dynamic joining and leaving of nodes in the space-ground integrated network lead to frequent changes in network topology. Traditional topology discovery mechanisms based on fixed periods face 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 algorithms. If the topology discovery period is too long, topology changes caused by emergencies will not be discovered in time, which may lead to outdated routes, packet loss, and rerouting will bring additional overhead. Based on this, considering that the topology changes of the space-ground integrated network have a certain degree of predictability, the periodic topology discovery is combined with the topology discovery based on topology prediction and the topology discovery based on active detection. An adaptive topology discovery and maintenance mechanism is proposed to ensure timely and accurate topology information while reducing the signaling load. As shown in Figure 3(1), a detection packet is sent at a period of time T to perform topology detection. If the topology change is predicted based on the node's running trajectory, speed, time and other information, and a detection packet is sent when a link is disconnected or connected, and topology detection and maintenance are performed at a period greater than T at other times, the overhead can be effectively reduced, as shown in Figure 3(2). For unpredictable topology changes caused by failures and other reasons, the event triggers the active sending of detection packets to ensure the timeliness of topology information, as shown in Figure 3(3).

[0162] Through the adaptive topology discovery and maintenance mechanism, the topology and available resources of the integrated space-ground network can be dynamically obtained as the input of the multi-service time deterministic routing algorithm, and the time-varying path with deterministic delay can be calculated and converted into a routing table with time attributes, that is, including the start and end time of each hop transmission. The relationship between the modules in the protocol is as follows Figure 4 shown.

[0163] 2) Time-triggered packet forwarding mechanism

[0164] This embodiment considers that periodic and non-periodic data in the TSN technology are transmitted together in the same network, divides service groups into time-deterministic service groups and ordinary service groups (ordinary services have no delay guarantee), and uses a time-triggered mechanism to implement packet forwarding.

[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, the 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 it is necessary to host the node, set a timer according to the routing table information, and transmit data after the timer expires. For ordinary services that do not have strict latency guarantee requirements, under the premise of not affecting the transmission of time-deterministic services, the storage-hosting-forwarding of packets is realized through the IPv6 process according to the uniformly calculated routing table.

[0166] Compared with the prior art, the present invention aims at the routing problem of end-to-end transmission of services in the space-ground integrated network, and proposes a space-ground integrated network time deterministic routing algorithm and protocol based on time-varying graph to achieve 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 of multi-dimensional resources in the space-ground integrated network at all times, including network topology, link connectivity, link bandwidth, node cache, etc.

[0167] On this basis, the present invention further proposes a service-oriented time-deterministic routing algorithm, which can build the shortest latency path for the service based on the transmission requirements of the service, taking into account factors such as transmission volume, start time, link connectivity opportunities, and node storage resources. This design can ensure that the end-to-end transmission requirements of the service in a time-varying environment are met, while effectively improving the utilization of network resources.

[0168] In addition, the present invention 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 a time-varying network environment with intermittent connectivity. This protocol can better adapt to the time-varying characteristics of the integrated space-ground network and meet the time-deterministic requirements of service transmission.

[0169] The advantages of the present invention are: fully utilizing node storage resources, effectively improving the utilization rate of time-varying link resources, thereby ensuring the real-time requirements of end-to-end transmission of services in a time-varying environment. In addition, the present invention can also achieve more efficient routing protocols and data forwarding, further improving network performance. At the same time, the algorithm and protocol also have good versatility and scalability, low computational complexity, and can adapt to business needs in different scenarios.

[0170] For the convenience of description, the above device is described in various units according to their functions. Of course, when implementing the present application, the functions of each unit can be implemented in the same or multiple software and / or hardware.

[0171] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0172] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or 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, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

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

[0174] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0175] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

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

[0177] The memory may include non-permanent storage in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0178] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be 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 erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0179] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0180] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0181] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the 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, wherein the plurality of nodes are connected by links, the changing link bandwidth and connection opportunities are depicted on the corresponding links in time sequence, and the storage capacity of the node is also characterized at the node, characterized in that 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 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 path in the time-varying continuous graph, calculate the corresponding link flow and path cumulative flow, including single-hop path flow and multi-hop path cumulative flow; Step 3: Construct a time-deterministic routing algorithm, including algorithm input and algorithm output; 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 space-ground integrated network based on time-varying graph according to claim 1 is characterized in that The physical nodes include physical entities such as satellites, spacecraft and ground stations.

3. The time-deterministic routing method for the space-ground integrated network based on the 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 space-ground integrated network based on 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 time 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), the service transmission start time t start (M) and the termination time t end (M) Determine the occupancy of all link connectivity periods and node storage on the path during end-to-end transmission of business data.

7. The time-deterministic routing method for space-ground integrated network based on 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 is 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 connection 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 the valid connection periods M A,B ,Right now in 8. The time-deterministic routing method for space-ground integrated network based on 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. For link (A, B), calculate the corresponding effective connection period 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 connection period of link (A, B) The transmitted data flow and related constraints can 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 get the end time of the effective connection period of link (B, C) And calculate the multi-hop path accumulation.

9. The time-deterministic routing method for space-ground integrated network based on time-varying graph according to claim 1 or 2, characterized in that The step three comprises: 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 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 the destination point D of the transmission; Algorithm output: The end-to-end time-varying path Path(M) from S to D, which 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 of 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, and is initialized to c[v]=∞, p[v]=-1 (-1 means 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, taking out the node u with the smallest node cost from Q as the current path-finding node, and updating 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 connection 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 is terminated; otherwise, execute S308; S308 , starting from D, using the previous hop node p[D] in sequence, obtain the path Path(M) from S to D, and record the effective connectivity period of each link in the path.

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

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