CN110391983B - Distributed congestion avoidance routing algorithm for satellite-ground integrated network - Google Patents

Abstract

Translated fromChinese

本发明公开了一种面向星地一体化网络的分布式拥塞避免路由算法，该算法包括：数据到达接入卫星；以接入卫星作为源节点，更新网关节点虚拟地址，计算接入卫星至各网关节点距离；选择距离最小的网关节点作为目的节点；以接入卫星作为当前节点，判断当前节点是否为目的节点，若是，则输出最优路径；若不是，根据当前节点和目的节点的虚拟地址判断备选转发方向，并根据链路拥塞状况判定下一跳转发方向，数据跳转至下一跳节点；以下一跳节点作为当前节点，重复上述过程，直至当前节点为目的节点。本发明的面向星地一体化网络的分布式拥塞避免路由算法，加入了多网关节点选择问题。每个节点只需自身链路状态信息即可判断转发方向，避免拥塞。

The invention discloses a distributed congestion avoidance routing algorithm oriented to a satellite-ground integrated network. The algorithm includes: data arriving at an access satellite; using the access satellite as a source node, updating the virtual address of a gateway node, and calculating the access satellite to each Gateway node distance; select the gateway node with the smallest distance as the destination node; take the access satellite as the current node, determine whether the current node is the destination node, if so, output the optimal path; if not, according to the virtual address of the current node and the destination node Determine the alternate forwarding direction, and determine the next-hop forwarding direction according to the link congestion status, and the data is jumped to the next-hop node; the next-hop node is used as the current node, and the above process is repeated until the current node is the destination node. The distributed congestion avoidance routing algorithm for the satellite-ground integrated network of the present invention adds the problem of multi-gateway node selection. Each node only needs its own link state information to determine the forwarding direction to avoid congestion.

Description

Distributed congestion avoidance routing algorithm for satellite-ground integrated network

Technical Field

The invention relates to the technical field of signal transmission, in particular to a satellite-ground integrated network-oriented distributed congestion avoidance routing algorithm.

Background

The satellite-ground integrated network system mainly comprises a space access network (satellite network), a ground core network and a user domain. A link is established between communication equipment of a ground user and a satellite, data of the user is transmitted to the satellite and then forwarded to a ground gateway station through an inter-satellite link, the gateway station is accessed to a ground core network and is transmitted to a final destination in the ground core network, and return data is transmitted back to the ground user through an opposite path. In order to transmit data smoothly in the satellite network, it is necessary to provide a routing algorithm.

In the low earth orbit satellite network constellation configuration and the inter-satellite link which are widely adopted at present, each satellite is used as a network node, and the satellite network can be regarded as a mesh network. In the prior art, a minimum transmission delay routing algorithm is generally adopted for data transmission, and a specific gateway station is selected as a destination node for data forwarding. After the destination node is determined, the shortest time delay path is searched as the optimal path from the source node to the destination node by analyzing the link distance characteristics between the satellites.

The inventor finds that the prior art has at least the following problems: when a plurality of gateway stations exist in the satellite-ground integrated network system, the routing algorithm cannot accurately select a proper gateway station as a destination node, and the calculation cost is high. And due to the problem of network traffic congestion, the shortest delay path often cannot achieve the globally optimal transmission effect of the network.

Disclosure of Invention

In order to solve the technical problems in the prior art, the invention provides a distributed congestion avoidance routing algorithm for a satellite-ground integrated network. The specific technical scheme is as follows:

a distributed congestion avoidance routing algorithm for a satellite-to-ground integrated network, the algorithm comprising: data arrives at the access satellite; updating the virtual address of the gateway node by taking the access satellite as a source node, and calculating the distance from the access satellite to each gateway node; selecting the gateway node with the minimum distance as a destination node; taking the access satellite as a current node, judging whether the current node is a target node or not, and if so, outputting an optimal path; if not, judging the alternative forwarding direction according to the virtual addresses of the current node and the destination node, judging the next hop forwarding direction according to the link congestion condition, and skipping the data to the next hop node; and repeating the process by taking the next hop node as the current node until the current node is the destination node.

In one possible design, the satellite nodes are numbered using two-dimensional arrays (v, h) with the virtual addresses of the two satellites being (v, h), respectively_i,h_i) And (v)_j,h_j) Obtaining the distance between the two satellites by the following formula:

d(S_i,S_j)＝|h_i-h_j|+min{|v_i-v_j|,n₂-|v_i-v_j|}

in the formula, a two-dimensional array (v)_d,h_d) V is the serial number in the satellite orbit plane, h is the serial number of the orbit plane of the satellite, v is more than or equal to 1 and less than or equal to n₂，1≤h≤n₁，d(S_i,S_j) Representing the distance between the two satellites.

In one possible design, let the virtual address of the current node be (v)_c,h_c) The virtual address of the destination node is (v)_d,h_d) The lateral distance n between the current node and the destination node_H＝|h_d-h_cL, longitudinal distance n_V＝min{|v_d-v_c|,n₂-|v_d-v_c|}。

In one possible design, after the transverse distance and the longitudinal distance between the current node and the destination node are obtained, if the transverse distance and the longitudinal distance are both 0, the data is transmitted to the destination node; if the transverse distance is not 0, the longitudinal distance is 0, and the alternative forwarding direction is transverse forwarding; if the transverse distance is 0, the longitudinal distance is not 0, and the alternative forwarding direction is longitudinal forwarding; and if the transverse distance and the longitudinal distance are not 0, the alternative forwarding directions comprise transverse forwarding and longitudinal forwarding.

In one possible design, the algorithm further includes: the current node monitors the congestion condition of an inter-satellite link connected with the current node in real time, and if the buffer occupancy of the link is smaller than a congestion state threshold value, the link is judged to be in an idle state; and if the buffer occupancy of the link is larger than the congestion state threshold, judging that the link is in the congestion state.

In one possible design, determining an alternative forwarding direction according to virtual addresses of a current node and a destination node, and determining a next-hop forwarding direction according to a link congestion condition includes:

if only one alternative forwarding direction is available, judging whether the link of the direction is congested, if not, forwarding along the direction, and if so, entering a buffer queue to wait for the link to be idle;

if there are two alternative directions, judging whether the links of the two directions are congested, if one direction is idle and the other direction is congested, selecting the idle direction for forwarding; if the two directional links are congested, judging the length of a buffer queue of the two directional links, selecting the direction with the short buffer queue as a forwarding direction, and adding data into the direction buffer queue; and if the two direction links are not congested, selecting the direction with longer distance for forwarding.

In one possible design, the access satellite accesses the terrestrial core network through a gateway station corresponding to the destination node.

In a possible design, after the backhaul data sent by the ground core network reaches the gateway node, the gateway node is used as a source node, the access satellite node is used as a destination node, the backhaul data jumps step by step between the source node and the destination node, and finally returns to the user through a satellite-to-ground link accessed to the satellite node.

The technical scheme of the invention has the following main advantages:

the distributed congestion avoidance routing algorithm for the satellite-ground integrated network disclosed by the invention is characterized in that the distance from the access satellite to each gateway node is calculated, and the gateway node with the minimum distance is selected as a target node. The routing algorithm is added with the multi-gateway node selection problem, the target node is determined by relying on the virtual address information of the satellite, the coverage relation of the satellite to the ground area does not need to be calculated, and the calculation cost is reduced. In the step-by-step skipping process of the source node and the destination node, the alternative forwarding direction is judged through the virtual addresses of the current node and the destination node, the next-hop forwarding direction is judged according to the link congestion state, each node can judge the forwarding direction only through the link state information of the node, congestion can be avoided, the transmission overhead of signaling information is reduced, agent agents are not needed, and the method is simple and easy to implement.

Drawings

The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. In the drawings:

fig. 1 is a schematic diagram of a satellite network constellation configuration and an inter-satellite link design according to an embodiment of the present invention;

fig. 2 is a flowchart of a distributed congestion avoidance routing algorithm for a satellite-ground integrated network according to an embodiment of the present invention;

FIG. 3 is a flow chart of the next hop forwarding direction determination according to an embodiment of the present invention;

fig. 4 is a comparison diagram of the average propagation delay simulation results of the distributed congestion avoidance routing algorithm and the minimum delay algorithm for the satellite-ground integrated network according to an embodiment of the present invention;

fig. 5 is a comparison diagram of a simulation result of load balancing coefficients of a distributed congestion avoidance routing algorithm and a minimum delay algorithm for a satellite-ground integrated network according to an embodiment of the present invention;

fig. 6 is a graph comparing the packet loss rate simulation results of the distributed congestion avoidance routing algorithm and the minimum delay algorithm for the satellite-ground integrated network according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the specific embodiments of the present invention and the accompanying drawings. It is to be understood that the described embodiments are merely a few embodiments of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.

The technical scheme provided by the embodiment of the invention is described in detail below with reference to the accompanying drawings.

The distributed congestion avoidance routing algorithm for the satellite-ground integrated network, provided by the embodiment of the invention, is suitable for satellite network constellation configuration and inter-satellite link design shown in figure 1. The satellite network space section mainly comprises low earth orbit satellites and inter-satellite links. The constellation configuration adopts a low-orbit near-polar orbit Walker constellation, n₁Each track surface is distributed in a pi shape, and n is uniformly distributed in each track surface₂And (4) a satellite. The satellite has on-board processing and forwarding functions. Each satellite can establish four inter-satellite links, which establish the same-orbit inter-satellite links with the front and rear satellites in the orbital plane and establish the different-orbit inter-satellite links with the left and right satellites in the orbital plane. Wherein, 1 st and n th₁A 'gap' is formed between the orbital planes, and an inter-satellite link is not established. At delta_maxIs a polar region latitude threshold value, when satellite subsatellite point latitude | delta | is greater than delta_maxAnd when the satellite is in the polar region, disconnecting the inter-orbital satellite link connected with the satellite. And when the satellite flies out of the polar region, the inter-heterotactic inter-satellite link is rebuilt.

The embodiment of the invention provides a satellite-ground integrated network-oriented distributed congestion avoidance routing algorithm, as shown in fig. 2, the algorithm comprises:

the data arrives at the access satellite.

And updating the virtual address of the gateway node by taking the access satellite as a source node, and calculating the distance from the access satellite to each gateway node.

And selecting the gateway node with the minimum distance as the destination node.

Taking the access satellite as a current node, judging whether the current node is a target node or not, and if so, outputting an optimal path; if not, judging the alternative forwarding direction according to the virtual addresses of the current node and the destination node, judging the next hop forwarding direction according to the link congestion condition, and skipping the data to the next hop node; and repeating the process by taking the next hop node as the current node until the current node is the destination node.

The distributed congestion avoidance routing algorithm for the satellite-ground integrated network, provided by the embodiment of the invention, selects the gateway node with the minimum distance as the destination node by calculating the distance from the access satellite to each gateway node. The problem of multi-gateway node selection is added in a routing algorithm, a target node is determined by relying on virtual address information of a satellite, the coverage relation of the satellite to a ground area does not need to be calculated, and calculation cost is reduced. In the step-by-step skipping process of the source node and the destination node, the alternative forwarding direction is judged through the virtual addresses of the current node and the destination node, the next-hop forwarding direction is judged according to the link congestion state, each node can judge the forwarding direction only through the link state information of the node, congestion can be avoided, the transmission overhead of signaling information is reduced, agent agents are not needed, and the method is simple and easy to implement.

In the satellite-ground integrated network system, a gateway station establishes a satellite-ground link with a satellite with the largest air elevation angle above the gateway station, and the satellite is called a gateway satellite. In the process of satellite movement, the gateway satellite corresponding to the gateway station is continuously updated, so that the gateway station always selects the satellite with the largest elevation angle to become the gateway satellite. The gateway satellites correspond to the gateway stations one by one, the number of the gateway nodes is equal to that of the gateway stations, and no gateway station exists in the polar region. In the satellite network, each satellite has the same performance, and can be called a gateway node along with the movement of the satellite. After receiving the data of the ground user, a certain access satellite becomes a source node, the satellite selects a gateway node as a destination node at the source node, and then hop-by-hop forwarding is carried out between the source node and the destination node to complete the routing process.

In the embodiment of the invention, the access satellite is used as a source node, the distance between the access satellite and each gateway node is calculated, and the gateway node with the minimum distance is selected as a destination node. Therefore, it is necessary to provide an inter-satellite distance obtaining method, and optionally, the embodiment of the present invention obtains the inter-satellite distance by:

a two-dimensional array (v,h) numbering the satellite nodes to make the virtual addresses of two satellites respectively be (v)_i,h_i) And (v)_j,h_j) Obtaining the distance between the two satellites by the following formula:

d(S_i,S_j)＝|h_i-h_j|+min{|v_i-v_j|,n₂-|v_i-v_j|}

in the formula, v in the two-dimensional array (v, h) is the number in the satellite orbital plane, h is the number in the orbital plane of the satellite, and v is more than or equal to 1 and less than or equal to n₂，1≤h≤n₁，d(S_i,S_j) Representing the distance between the two satellites.

Based on the above, let the virtual address of the current node be (v)_c,h_c) The virtual address of the destination node is (v)_d,h_d) Defining a lateral distance n between the current node and the destination node_H＝|h_d-h_cL, longitudinal distance n_V＝min{|v_d-v_c|,n₂-|v_d-v_c|}。

Further, the gateway node selection method is as follows: each node S_kComputing and gateway nodes G_iSelecting the gateway node with the smallest distance as the destination node G (S)_k). (when the gateway node with the smallest distance is not unique, the gateway node with the smallest number is selected.)

That is, the access satellite selects the gateway node with the smallest distance as the destination node by the above method. And after the destination node is determined, the access satellite accesses the ground core network through the gateway station corresponding to the destination node.

How to judge the alternative forwarding direction according to the virtual addresses of the current node and the destination node is exemplified as follows:

after the transverse distance and the longitudinal distance between the current node and the target node are obtained, if the transverse distance and the longitudinal distance are both 0, the data are transmitted to the target node; if the transverse distance is not 0, the longitudinal distance is 0, and the alternative forwarding direction is transverse forwarding; if the transverse distance is 0, the longitudinal distance is not 0, and the alternative forwarding direction is longitudinal forwarding; and if the transverse distance and the longitudinal distance are not 0, the alternative forwarding directions comprise transverse forwarding and longitudinal forwarding.

And after the alternative forwarding direction is determined, determining the next hop forwarding direction according to the congestion condition of the link. In the embodiment of the invention, the link congestion condition is determined by the following modes:

the current node monitors the congestion condition of the inter-satellite link connected with the current node in real time, and if the occupancy of the link cache is smaller than the congestion state threshold T_CJudging that the link is in an idle state; if the link buffer occupation amount is larger than the congestion state threshold T_CThen, the link is determined to be in a congested state.

Specifically, determining an alternative forwarding direction according to virtual addresses of a current node and a destination node, and determining a next-hop forwarding direction according to a link congestion status, as shown in fig. 3, includes:

if only one alternative forwarding direction exists, judging whether the link of the direction is congested, if not, forwarding along the direction, and if so, entering a buffer queue to wait for the link to be idle.

If there are two alternative directions, judging whether the links of the two directions are congested, if one direction is idle and the other direction is congested, selecting the idle direction for forwarding; if the two directional links are congested, judging the length of a buffer queue of the two directional links, selecting the direction with the short buffer queue as a forwarding direction, and adding data into the direction buffer queue; and if the two direction links are not congested, selecting the direction with longer distance for forwarding.

And the data jumps step by step between the source node and the destination node through the routing algorithm, and the data transmission path determined through the process is the optimal path of the algorithm.

Based on the same reason, after the backhaul data sent by the ground core network reaches the gateway node, the gateway node is used as a source node, the access satellite node is used as a destination node, the backhaul data jumps step by step between the source node and the destination node, and finally returns to the user through a satellite-ground link accessed to the satellite node.

The following describes beneficial effects of the distributed congestion avoidance routing algorithm for a satellite-ground integrated network according to the embodiment of the present invention with reference to specific examples:

and carrying out simulation verification on the distributed congestion avoidance routing algorithm facing the satellite-ground integrated network by adopting a simulation method. The constellation configuration adopts polar orbit constellation, the orbit height is 1200km, the number n1 of orbit surfaces is 18, and the number n of satellites in each orbit surface₂Total number of satellites N36_sat648, the phase difference Δ f between adjacent orbiting satellites is 5deg, and the threshold value of the polar region dimension is δ_max70deg, with the number of gateway stations set to N_GThe simulation time was 24h, 12.

Simulation results of the distributed congestion avoidance routing algorithm for the satellite-ground integrated network and the minimum delay routing algorithm provided by the prior art are shown in fig. 4 to fig. 6. Simulation results show that compared with a minimum delay routing algorithm, the distributed congestion avoidance routing algorithm for the satellite-ground integrated network has smaller average propagation delay difference, and the overall load balance and packet loss rate performance of the network are greatly improved, which shows that the routing algorithm of the embodiment of the invention has congestion avoidance capability.

It is noted that, in this document, relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," 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 but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. In addition, "front", "rear", "left", "right", "upper" and "lower" in this document are referred to the placement states shown in the drawings.

Finally, it should be noted that: the above examples are only for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims (2)

Translated fromChinese

1.一种面向星地一体化网络的分布式拥塞避免路由算法，其特征在于，所述算法包括：1. a distributed congestion avoidance routing algorithm for a satellite-ground integrated network, characterized in that the algorithm comprises:数据到达接入卫星；Data arrives at the access satellite;以接入卫星作为源节点，更新网关节点虚拟地址，计算接入卫星至各网关节点距离；Take the access satellite as the source node, update the virtual address of the gateway node, and calculate the distance from the access satellite to each gateway node;选择距离最小的网关节点作为目的节点；Select the gateway node with the smallest distance as the destination node;以接入卫星作为当前节点，判断当前节点是否为目的节点，若是，则输出最优路径；若不是，根据当前节点和目的节点的虚拟地址判断备选转发方向，并根据链路拥塞状况判定下一跳转发方向，数据跳转至下一跳节点；以下一跳节点作为当前节点，重复判断当前节点是否为目的节点的过程，直至当前节点为目的节点；Take the access satellite as the current node, determine whether the current node is the destination node, and if so, output the optimal path; if not, determine the alternate forwarding direction according to the virtual addresses of the current node and the destination node, and determine the lower One hop forwarding direction, the data jumps to the next hop node; the next hop node is used as the current node, and the process of judging whether the current node is the destination node is repeated until the current node is the destination node;其中，采用二维数组(v,h)对卫星节点进行编号，令两个卫星的虚拟地址分别为(v_i,h_i)和(v_j,h_j)，通过下述公式，获取两卫星间的距离：Among them, the two-dimensional array (v, h) is used to number the satellite nodes, and the virtual addresses of the two satellites are respectively (v_i , h_i ) and (v_j , h_j ), and the following formulas are used to obtain the two satellites. distance between:d(S_i,S_j)＝|h_i-h_j|+min{|v_i-v_j|,n₂-|v_i-v_j|}d(S_i ,S_j )=|h_i -h_j |+min{|v_i -v_j |,n₂ -|v_i -v_j |}式中，二维数组(v,h)中v为卫星轨道面内编号，h为卫星所在轨道面编号，1≤v≤n₂，1≤h≤n₁，d(S_i,S_j)表示两卫星间的距离，n₁表示轨道面个数，n₂表示每个轨道面内均匀分布的卫星个数；In the formula, in the two-dimensional array (v,h), v is the number of the satellite orbital plane, h is the orbital plane number of the satellite, 1≤v≤n₂ , 1≤h≤n₁ , d(S_i ,S_j ) Represents the distance between two satellites, n₁ represents the number of orbital planes, and n₂ represents the number of satellites evenly distributed in each orbital plane;其中，设定当前节点的虚拟地址为(v_c,h_c)，目的节点的虚拟地址为(v_d,h_d)，当前节点与目的节点之间的横向距离n_H＝|h_d-h_c|，纵向距离n_V＝min{|v_d-v_c|,n₂-|v_d-v_c|}；Among them, set the virtual address of the current node as (v_c , h_c ), the virtual address of the destination node as (v_d , h_d ), and the horizontal distance between the current node and the destination node n_H =|h_d -h_c |, the longitudinal distance n_V =min{|v_d -v_c |,n₂ -|v_d -v_c |};其中，选择距离最小的网关节点作为目的节点，包括：每个节点S_k计算与各网关节点G_i的距离，选择距离最小的网关节点作为其目的节点G(S_k)，当距离最小的网关节点不唯一时，选择编号序数最小的网关节点；Among them, selecting the gateway node with the smallest distance as the destination node includes: calculating the distance between each node_Sk and each gateway node G_i , selecting the gateway node with the smallest distance as its destination node G(S_k ), when the gateway with the smallest distance When the node is not unique, select the gateway node with the smallest serial number;其中，在确定目的节点后，接入卫星通过与目的节点对应的信关站接入地面核心网；Wherein, after the destination node is determined, the access satellite is connected to the ground core network through the gateway station corresponding to the destination node;其中，根据当前节点和目的节点的虚拟地址判断备选转发方向，包括：获取当前节点与目的节点之间的横向距离和纵向距离后，若横向距离和纵向距离均为0，则数据已传输到目的节点；若横向距离不为0，纵向距离为0，备选转发方向为横向转发；若横向距离为0，纵向距离不为0，备选转发方向为纵向转发；若横向距离和纵向距离均不为0，备选转发方向包括横向转发和纵向转发；Wherein, judging the alternative forwarding direction according to the virtual addresses of the current node and the destination node includes: after obtaining the horizontal distance and the vertical distance between the current node and the destination node, if the horizontal distance and the vertical distance are both 0, the data has been transmitted to Destination node; if the horizontal distance is not 0, the vertical distance is 0, and the alternate forwarding direction is horizontal forwarding; if the horizontal distance is 0, and the vertical distance is not 0, the alternate forwarding direction is vertical forwarding; if the horizontal distance and vertical distance are both If it is not 0, the alternate forwarding directions include horizontal forwarding and vertical forwarding;其中，通过以下方式确定链路拥塞状况：当前节点实时监测与自身相连的星间链路拥塞情况，若链路缓存占用量小于拥塞状态阈值时，判定该链路为空闲状态；若链路缓存占用量大于拥塞状态阈值时，判定该链路为拥塞状态；Among them, the link congestion status is determined by the following methods: the current node monitors the congestion status of the inter-satellite link connected to itself in real time, and if the link buffer occupancy is less than the congestion status threshold, it is determined that the link is in an idle state; if the link buffer When the occupancy is greater than the congestion state threshold, it is determined that the link is in a congestion state;其中，根据链路拥塞状况判定下一跳转发方向，包括：若备选转发方向只有一个，则判断该方向链路是否拥塞，若不拥塞，则沿该方向转发，若拥塞，则进入缓存队列等待链路空闲；若备选方向有两个，则判断两个方向链路是否拥塞，若一个方向空闲，另一方向拥塞，则选择空闲方向转发；若两个方向链路均拥塞，则判断两个方向链路缓存队列长度，选择缓存队列短的方向作为转发方向，将数据加入该方向缓存队列；若两个方向链路均不拥塞，则选择距离较长的方向进行转发。Among them, determining the forwarding direction of the next hop according to the link congestion status includes: if there is only one alternate forwarding direction, determining whether the link in this direction is congested; if not, forwarding in this direction; if congested, entering the cache The queue waits for the link to be idle; if there are two alternative directions, it is judged whether the link in the two directions is congested. If one direction is idle and the other direction is congested, the idle direction is selected for forwarding; if both directions are congested, the Determine the length of the link buffer queue in the two directions, select the direction with the short buffer queue as the forwarding direction, and add the data to the buffer queue in this direction; if the links in both directions are not congested, the direction with the longer distance is selected for forwarding.2.根据权利要求1所述的面向星地一体化网络的分布式拥塞避免路由算法，其特征在于，地面核心网发出的回程数据到达网关节点后，以网关节点为源节点，接入卫星节点为目的节点，回程数据在源节点与目的节点之间逐级跳转，最终经接入卫星节点的星地链路返回至用户。2. The distributed congestion avoidance routing algorithm for a satellite-ground integrated network according to claim 1, characterized in that, after the backhaul data sent by the ground core network reaches the gateway node, the gateway node is used as the source node, and the satellite node is accessed. For the destination node, the backhaul data hops step by step between the source node and the destination node, and finally returns to the user via the satellite-ground link connected to the satellite node.

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