A routing control method for downlink congestion in MLSN network

Abstract

The present invention discloses a routing control method for downlink congestion in an MLSN network. The method comprises the following steps: firstly constructing a satellite network architecture model and generating a MEO layer routing table and a LEO layer routing table; when sending a data packet, a ground terminal encapsulates a source cluster identifier and a destination cluster identifier, and clusters the satellites of the MEO layer and the LEO layer, wherein each satellite of the MEO layer manages a group of cluster member LEO satellites as a cluster head; the number of MEO satellites is the same as the number of clusters; when the ground terminal has a delay in sending and receiving data packets, the LEO satellite node detects the LEO layer link state and calculates the link load threshold; finally, the MEO satellite receives the broadcast data packet and link state update of the LEO, and performs data routing forwarding according to the link load threshold. The present invention combines the threshold idea to minimize the packet loss of the link during data forwarding; when performing data packet forwarding and allocation, the MEO-ground link is used as a circuitous path to solve the problem of downlink congestion in the MLSN network, reducing the packet loss rate by 5%.

Description

Technical Field

[0001] The invention belongs to the technical field of satellite networks, and in particular relates to a routing control method for downlink congestion in an MLSN network. Background Art

[0002] Satellite networks have received increasing attention as a means of providing next-generation networks that enable ubiquitous networks. Satellite networks can generally be classified as geostationary orbit (GEO) satellite networks or non-geostationary orbit (NGEO) satellite networks. A special type of satellite network that can be built by layering NGEO satellite networks is called a multi-layer satellite network (MLSN). In MLSN, there are six different links, namely, inter-satellite links in the LEO and MEO layers, upper and lower inter-layer links, and upper and lower links between the LEO layer and the ground, which are called LEO-LEO, MEO-MEO, LEO-MEO, MEO-LEO, ground-LEO, and LEO-ground. The various link paths can be used as detour paths, allowing the load to be distributed among satellites. With this feature, even if some satellites are hit and suffer heavy traffic loads, congestion can be avoided by using the link paths in MLSN.

[0003] Existing routing control methods can only avoid or alleviate congestion within the LEO layer, resulting in high link packet loss rate and increased end-to-end delay. Summary of the invention

[0004] In order to solve the technical problems mentioned in the above background technology, the present invention proposes a routing control method for downlink congestion in an MLSN network.

[0005] In order to achieve the above technical objectives, the technical solution of the present invention is:

[0006] A routing control method for downlink congestion in an MLSN network comprises the following steps:

[0007] S1. Build a satellite network architecture model and generate a MEO layer routing table and a LEO layer routing table;

[0008] S2. When sending a data packet, the ground terminal encapsulates the source cluster identifier and the destination cluster identifier, and clusters the satellites in the MEO layer and the LEO layer. Each satellite in the MEO layer acts as a cluster head to manage a group of cluster member LEO satellites. The number of MEO satellites is the same as the number of clusters.

[0009] S3, when the ground terminal experiences a delay in sending and receiving data packets, the LEO satellite node detects the LEO layer link status and calculates the link load threshold;

[0010] S4. The MEO satellite receives the broadcast data packet and link status update from the LEO, and performs data routing and forwarding according to the link load threshold in step S3.

[0011] Preferably, step S1 comprises the following steps:

[0012] S11, the satellite broadcasts a Hello message to neighboring node satellites within one hop range, the message contains the satellite node ID and inter-satellite link status information;

[0013] S12. The node receiving the Hello request message determines the type of the Hello message. If it is a request message type, the receiving node feeds back a Hello response message to the sending node and adds the information in the message to its own neighbor table. If it is a Hello response message or a Hello update message, the receiving node updates its own neighbor table according to the message.

[0014] S13. The satellite periodically sends a Hello update message to update the routing table.

[0015] Preferably, step S2 comprises the following steps:

[0016] S21, designate a satellite in the MEO layer as the cluster head k1;

[0017] S22, according to the speed of the LEO satellite node and the link connectivity between the LEO satellite node and the satellite nodes of the MEO layer, the LEO satellite is allocated to the cluster of the cluster head k1;

[0018] S23, select the next cluster head ki according to the roulette algorithm; repeat step S22 to cluster all LEO layer satellites;

[0019] S24, the MEO satellite as the cluster head broadcasts a HELLO message to the LEO satellites within two hops, the message including the cluster head information;

[0020] S25, after receiving the HELLO message, the LEO satellite determines whether there are multiple cluster head MEO satellite information in the routing table. If there are multiple cluster head MEO satellite information, only the satellite information of one cluster head MEO is retained, and other cluster head MEO satellites are rejected.

[0021] Preferably, step S3 comprises the following steps:

[0022] S31, LEO satellite node detects real-time data packet queue length len i (t); when len i (t) is greater than or equal to the node packet queue length threshold len th When the LEO satellite A is determined to be in a congested state, data routing forwarding, i.e., routing control, is performed;

[0023] S32, according to the len detected in step S31 th , calculate the link load threshold Q th And upload to MEO satellite.

[0024] Preferably, step S32 includes the following steps:

[0025] Calculate the remaining time T of packet loss of LEO satellite node d The formula is as follows:

[0026]

[0027] Among them, p ave Average packet length, rate at which InputV packets flow into the LEO satellite, rate at which OutputV packets flow into the LEO satellite;

[0028] Define the link delay D link The formula is as follows:

[0029]

[0030] Among them, D broadcast is the propagation delay; D queue is the queuing delay; w is the weighting factor; P relative is the relative position of the two LEO satellites;

[0031] According to the remaining time T of packet loss d and link delay D link Calculate the link load threshold Q th ; The formula is as follows:

[0032]

[0033] in,

[0034] Preferably, step S4 comprises the following steps:

[0035] S41, when the source ground terminal S sends information to the destination ground terminal D, the LEO satellite receives the data packet sent by the terminal S;

[0036] S42, MEO determines the cluster identifier in the data packet sent by the ground terminal D based on the broadcast data packet forwarded by LEO; if the source cluster identifier and the destination cluster identifier are the same, the MEO satellite performs the forwarding function and checks the link load in the cluster; if the source cluster identifier and the destination cluster identifier are different, the MEO satellite performs the routing function, searches the MEO layer routing table, and finds the LEO satellite of the destination cluster for forwarding;

[0037] Preferably, in step S42, when the source cluster identifier and the destination cluster identifier are the same, if the link load of the LEO layer is less than the threshold Q th , check the routing table stored in the LEO satellite, and transmit it to the destination area terminal D through the LEO-LEO link and the LEO-ground link; if the link load of the LEO layer is greater than the threshold Q th , the data packet will be transmitted to the MEO satellite in a roundabout way. The MEO satellite directly establishes a link with the ground terminal, and the data packet is transmitted to the ground terminal D2 through the GEO-ground link.

[0038] Preferably, in step S42, when the source cluster identifier and the destination cluster identifier are different, if the link load of the LEO layer is less than the threshold Q th , check the routing table stored in the LEO satellite, and transmit it to the destination area terminal D through the LEO-LEO link and the LEO-ground link; if the link load of the LEO layer is greater than the threshold Q th , the data packet will be transmitted to the MEO satellite in a roundabout way. The MEO satellite directly establishes a link with the ground terminal, and the data packet is transmitted to the ground terminal D2 through the GEO-ground link.

[0039] The beneficial effects brought by adopting the above technical solution are:

[0040] The present invention proposes a routing control method for downlink congestion in an MLSN network. First, the LEO / MEO two-layer satellite topology is optimized by a clustering method, and a MEO-ground link is constructed as a new link outside the existing link. By using this link, the ground terminal can transmit data packets to the destination terminal without passing through the destination LEO satellite. Secondly, the present invention combines the threshold idea to minimize the packet loss of the link during data forwarding; when performing data packet forwarding distribution, the MEO-ground link is used as a detour path to solve the problem of downlink congestion in the MLSN network, further reducing the packet loss rate by 5%. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a logic diagram of a downlink congestion routing control method in an MLSN network;

[0042] Figure 2 This is a diagram of the data forwarding process. DETAILED DESCRIPTION

[0043] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.

[0044] The present invention proposes a routing control method for downlink congestion in an MLSN network, and the specific embodiments are as follows:

[0045] S1. Construct a two-layer satellite network architecture model and generate a MEO layer routing table and a LEO layer routing table;

[0046] S2, clustering the MEO satellites and LEO satellites, with the MEO satellite acting as a cluster head to manage a group of cluster member LEO satellites; the ground terminal will encapsulate the source cluster identifier and the destination cluster identifier when sending a data packet;

[0047] S3, clustering and routing table update are completed, and the LEO satellite node detects the LEO layer link status;

[0048] S31, LEO satellite node detects real-time data packet queue length len i (t), when len i (t) is greater than or equal to the node packet queue length threshold len th When , LEO satellite A is in a congested state; further, calculate the packet loss remaining time T of the LEO satellite node d :

[0049]

[0050] Among them, p ave Average packet length, rate at which InputV packets flow into the LEO satellite, rate at which OutputV packets flow into the LEO satellite;

[0051] S32. Define link delay: Among them, D broadcast is the propagation delay; D queue is the queuing delay; w is the weighting factor; P relative is the relative position of the two LEO satellites;

[0052] S33, the remaining time T of packet loss through step S21 d and the link delay D of step S23 link calculate Further estimate the link status to obtain the link load threshold And upload to MEO satellite

[0053] S4, MEO satellite receives LEO broadcast data packets and link status updates, and performs data routing and forwarding according to link load. The specific process is as follows: Figure 2 ;

[0054] S41, when the source ground terminal S sends information to the destination ground terminal D, the LEO satellite receives the data packet sent by the terminal S, and the MEO receives the broadcast data packet forwarded by the LEO, and determines the cluster identifier in the data packet sent by the ground terminal D;

[0055] S42 If the source cluster identifier and the destination cluster identifier are the same, the MEO satellite performs a forwarding function to check the link load within the cluster;

[0056] S42-1. When the link load of the LEO layer is less than the threshold Q th , check the routing table stored in the LEO satellite, and transmit it to the destination area terminal D through the LEO-LEO link and the LEO-ground link;

[0057] S42-2, when the link load of the LEO layer is greater than the threshold Q th , the data packet will be transmitted to the MEO satellite in a roundabout way. The MEO satellite directly establishes a link with the ground terminal, and the data packet is transmitted to the ground terminal D1 through the GEO-ground link.

[0058] S43: If the source cluster identifier and the destination cluster identifier are different, the MEO satellite performs the routing function, searches the MEO layer routing table, and finds the LEO satellite of the destination cluster for forwarding.

[0059] S43-1. When the link load of the LEO layer is less than the threshold Q th , check the routing table stored in the LEO satellite, and transmit it to the destination area terminal D through the LEO-LEO link and the LEO-ground link;

[0060] S43-2, when the link load of the LEO layer is greater than the threshold Q th , the data packet will be transmitted to the MEO satellite in a roundabout way. The MEO satellite directly establishes a link with the ground terminal, and the data packet is transmitted to the ground terminal D2 through the GEO-ground link.

[0061] The embodiments are only for illustrating the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention.

Claims

1. A routing control method for downlink congestion in a multi-layer satellite network, characterized in that: The following steps are involved: S1. Build a satellite network architecture model and generate a MEO layer routing table and a LEO layer routing table; S2. When sending a data packet, the ground terminal encapsulates the source cluster identifier and the destination cluster identifier, and clusters the satellites in the MEO layer and the LEO layer. Each satellite in the MEO layer acts as a cluster head to manage a group of cluster member LEO satellites. The number of MEO satellites is the same as the number of clusters. S3, when the ground terminal experiences a delay in sending and receiving data packets, the LEO satellite detects the LEO layer link status and calculates the link load threshold; S4. The MEO satellite receives the broadcast data packet and link status update from the LEO satellite, and performs data routing and forwarding according to the link load threshold in step S3.

2. The method for controlling downlink congestion in a multi-layer satellite network according to claim 1, characterized in that: Step S3 includes the following steps: S31, LEO satellite detection real-time data packet queue length len i (t); when len i (t) is greater than or equal to the node packet queue length threshold len th When the LEO satellite is in a congested state, the data is forwarded by routing, i.e., routing control. S32, according to the len detected in step S31 i (t), calculate the link load threshold Q th And upload to MEO satellite.

3. The routing control method for downlink congestion in a multi-layer satellite network according to claim 2, characterized in that: Step S32 includes the following steps: Calculate the remaining time T of packet loss for LEO satellite d The formula is as follows: Among them, P ave is the average length of data packets, InputV is the rate at which data packets flow into the LEO satellite, and OutputV is the rate at which data packets flow out of the LEO satellite; Define the link delay D link The formula is as follows: Among them, D broadcast is the propagation delay; D queue is the queuing delay; w is the weighting factor; P relative is the relative position of the two LEO satellites; According to the remaining time T of packet loss d and link delay D link Calculate the link load threshold Q th ; The formula is as follows:

4. The routing control method for downlink congestion in a multi-layer satellite network according to claim 3, characterized in that: Step S4 includes the following steps: S41, when the source ground terminal S sends information to the destination ground terminal D, the LEO satellite receives the data packet sent by the terminal S; S42. The MEO satellite determines the cluster identifier in the data packet sent by the ground terminal D based on the broadcast data packet forwarded by the LEO satellite. If the source cluster identifier and the destination cluster identifier are the same, the MEO satellite performs the forwarding function and checks the link load within the cluster. If the source cluster identifier and the destination cluster identifier are different, the MEO satellite performs the routing function, searches the MEO layer routing table, and finds the LEO satellite of the destination cluster for forwarding.

5. The routing control method for downlink congestion in a multi-layer satellite network according to claim 4, characterized in that: In step S42, when the source cluster identifier and the destination cluster identifier are the same, if the link load of the LEO layer is less than the threshold Q th , check the routing table stored in the LEO satellite, and transmit it to the ground terminal D through the LEO satellite-to-LEO satellite link and the LEO satellite-to-ground link; if the link load of the LEO layer is greater than the threshold Q th , the data packet will be transmitted to the MEO satellite in a roundabout way. The MEO satellite directly establishes a link with the ground terminal D, and the data packet is transmitted to the ground terminal D through the link from the MEO satellite to the ground.

6. A routing control method for downlink congestion in a multi-layer satellite network according to claim 4 or 5, characterized in that: In step S42, when the source cluster identifier and the destination cluster identifier are different, if the link load of the LEO layer is less than the threshold Q th , check the routing table stored in the LEO satellite, and transmit the data packet to the ground terminal D through the LEO satellite-LEO satellite link and the LEO satellite-ground link; if the link load of the LEO layer is greater than the threshold Q th , the data packet will be transmitted to the MEO satellite in a roundabout way. The MEO satellite directly establishes a link with the ground terminal D, and the data packet is transmitted to the ground terminal D through the link from the MEO satellite to the ground.

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