A low earth orbit satellite-oriented distributed multi-hop buffer-aided link selection method

Abstract

The application relates to a low-orbit satellite-oriented distributed multi-hop buffer-assisted link selection method and belongs to the technical field of communication. The method comprises the following steps: dividing a transmission time into multiple equal-length time slots; establishing a low-orbit satellite communication model of buffer-assisted relaying; taking the improvement of system average throughput as a target, a new link selection method is proposed, all available odd links and even links are alternately selected through mutual negotiation between the relay nodes, and distributed data transmission is realized. The application is suitable for satellite communication, can effectively deal with the sudden situation of node occupation, and significantly improves the throughput of the system.

Description

Technical Field

[0001] This invention belongs to the field of communication technology and relates to a distributed multi-hop buffered auxiliary link selection method for low-Earth orbit satellites. Background Technology

[0002] Compared to high-Earth orbit (PEO) satellites, low-Earth orbit (LEO) satellites offer obvious advantages as relays, including lower transmission latency, less path loss, smaller satellite terminal size, and lower cost. Furthermore, LEO satellites also possess key advantages in numerous aspects compared to 5G cellular mobile communication systems. Especially in sparsely populated areas or where establishing base stations is difficult, such as oceans and deserts, LEO satellite relay provides a viable solution for filling communication gaps. Therefore, as a global communication solution, LEO satellite network systems offer wide coverage and high transmission rates, demonstrating a significant advantage over terrestrial base stations and showing a rapidly developing trend.

[0003] Distributed selection allows decisions to be made across multiple nodes. Compared to centralized selection, the system's decisions no longer rely on a single node, reducing the risk of outages and providing higher fault tolerance. The complexity, geographical distribution, communication characteristics, and diverse needs of satellite communication systems all support distributed selection to meet the requirements of different users and applications, providing better performance and flexibility.

[0004] Buffer-assisted relay technology combines buffering and relay techniques, changing traditional transmission methods, optimizing channel utilization, and improving the transmission performance of relay cooperation. Multi-hop systems can improve system reliability by introducing buffer-assisted technology. When a relay node fails, data packets can be temporarily stored in a buffer, waiting for the node to recover before transmission.

[0005] Currently, some research has proposed link selection methods based on buffer-assisted relay, but most of them focus on two-hop three-point relay models or multi-hop systems with ground base stations as relays. However, few studies have jointly considered multi-hop systems with satellites as relay nodes, especially considering transmission under distance and link condition constraints. Summary of the Invention

[0006] In view of this, the purpose of this invention is to provide a distributed multi-hop buffer-assisted link selection method for low-Earth orbit satellites, in order to solve the sudden situation of link interruption caused by the occupation of relay nodes in the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A distributed multi-hop buffer-assisted link selection method for low-Earth orbit satellites, the method comprising:

[0009] The transmission time is divided into multiple time slots of equal length, each time slot including node negotiation time and data packet transmission time;

[0010] Establish a satellite communication model with buffer-assisted relay;

[0011] By negotiating connections among nodes in a satellite communication model, multiple links can transmit simultaneously without interference, thus achieving distributed data transmission.

[0012] Optionally, the method includes the following steps:

[0013] S1, initialize data information, divide time into an infinite number of equal-length time slots, and establish a K-hop system consisting of one source, one destination, and K-1 low-Earth orbit satellites as relays, where K is an even number; each relay is equipped with a buffer storing L data packets; the nodes in the system are labeled {N0, N1, ..., N...} K-1 N K}, where N0 and N K Representing the source node and destination node respectively, relay node N k The probability of it being occupied is P k , 1≤k≤K-1; the link between any two nodes is denoted as L. i There are K links in total, 1≤i≤K, that is: the link between N0 and N1 is L1, the link between N1 and N2 is L2, ..., N K-1 and N K The link between them is L K When node N k When it is occupied, the link L connected to it k and L k+1 All interruptions occurred; the system transmitted a total of M data packets, each carrying R0 bits of information;

[0014] S2, determine the current time slot. If it is an odd time slot, go to S3; if it is an even time slot, go to S4.

[0015] S3, each even-numbered node N in the link even Next node N even+1 Send message If 0 ≤ even ≤ K-2, the message sent Represents the current node N even If the data packet is available and there is a data packet in the buffer, then node N... even It can transmit and expects to connect to the next node; if Indicates the current node N even If the buffer is unavailable or contains no packets, then node N... even Unable to transmit;

[0016] Odd node N even+1 Received message from the previous even-numbered node Then, make the final connection decision and send the decision message. Send to the previous node; when both of the following conditions are met: Node N even+1 When available and the buffer is not full. At this time, node N even+1 With node N even Connection, N even Send the first data packet in the buffer queue, N. even+1 After receiving a data packet, it is temporarily stored in a buffer queue; otherwise, At this time, node N even+1 Do not connect to the previous node; the node retains its original state.

[0017] Let t be the time slot when the i-th data packet arrives at node N1. start (i), 0<i≤M, represents the time slot in which the data packet begins to be transmitted;

[0018] S4, each odd-numbered node N in the link odd Next node N odd+1 Send message If 1 ≤ odd ≤ K-1, then the message sent... Represents the current node N odd If the data packet is available and there is data in the buffer queue, then node N... odd It can transmit data and expects to connect to the next node; if Represents the current node N odd If the data packet is unavailable or there is no data packet in the buffer, then node N... odd Unable to transmit;

[0019] Each even-numbered node N odd+1 Received message Then, make the final connection decision and send the decision message. Send to the previous node; when both of the following conditions are met: Node N odd+1 When available and the buffer is not full. At this time, node N odd+1 With node N odd Connection, node N odd Send the first data packet in the buffer queue, N. odd+1 After receiving a data packet, it is temporarily stored in a buffer queue; otherwise, At this time, node N odd+1 Do not connect to the previous node; the link remains in its original state.

[0020] Determine whether the i-th data packet has arrived at node N.K If yes, it indicates that the data packet has been successfully transmitted, and the corresponding time slot t will be... end (i) is denoted as the time slot at which the data packet transmission ends;

[0021] Step S5: Determine whether the transmission of M data packets is complete. If the transmission is complete, the transmission ends; otherwise, go to S2 until the transmission of M data packets is complete.

[0022] Optionally, the odd-numbered time slots can only be transmitted via odd-numbered links, and the status of node N1 is observed to determine whether the source end has sent data packets; the even-numbered time slots can only be transmitted via even-numbered links, and the status of node N1 is observed to determine whether the source end has sent data packets. K-1 The status is used to determine whether the data packet has reached the destination.

[0023] If an available link exists in each time slot, the system will not experience an interruption. This distributed selection method increases the system's flexibility and fault tolerance. Even if some links are interfered with or interrupted, the system can continue transmission as long as available links remain. Compared to centralized selection, it does not rely on a single central node. This is particularly important for applications requiring high reliability, such as satellite communications, which are typically better suited to distributed selection methods to mitigate the risk of system outages caused by link failures.

[0024] The beneficial effects of this invention are as follows: By dividing the transmission time into multiple time slots, aiming to maximize the average throughput of the system, and combining the real-time status of the buffer, this invention proposes an alternating selection scheme, which alternately selects all available odd and even links for transmission in odd and even time slots, thereby realizing distributed data transmission and improving the system resource utilization efficiency and average throughput.

[0025] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0026] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0027] Figure 1 This is a system diagram of the present invention;

[0028] Figure 2 This is a flowchart illustrating the method described in this invention;

[0029] Figure 3This invention presents the average delay curve of the system under different buffer sizes and different node occupancy probabilities.

[0030] Figure 4 This invention presents the average throughput curve of the system under different buffer sizes and different node occupancy probabilities.

[0031] Figure 5 This is the average latency curve of the system under different total number of data packets and different number of hops according to the present invention;

[0032] Figure 6 This is the average throughput curve of the system under different total number of data packets and different number of hops according to the present invention. Detailed Implementation

[0033] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0034] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0035] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0036] like Figure 1As shown, the system comprises a source terminal S, a destination terminal D, and K-1 low-Earth orbit satellite relays for decoding and forwarding. Each relay is equipped with a buffer capable of storing L data packets. All relays operate in half-duplex mode and cannot transmit or receive simultaneously. Assume K is even. Assume there is no direct link between the source and destination terminals; transmission occurs sequentially through the K-1 relays. Each relay receives a data packet, stores it in its buffer, and then transmits it to the next node only when the current node connects to the next node. In this system, time is divided into an infinite number of equal-length time slots. In odd-numbered time slots, all available odd-numbered links transmit simultaneously; in even-numbered time slots, all available even-numbered links transmit simultaneously. The system transmits M data packets, each carrying R0 bits of information.

[0037] Figure 2 The flowchart of the proposed method is shown below, illustrating the negotiation process of the link in the j-th and (j+1)-th time slots:

[0038] Assuming we are currently in the j-th time slot (j is an odd number), firstly, all even-numbered nodes N in the link... even (0≤even≤K-2) to the next node N even+1 Send message If the message is sent Represents the current node N even Available and the current relay's buffer is not empty (it already stores data packets); if Indicates the current node N even Unavailable or no data packets in the buffer. Secondly, for each odd-numbered node N... even+1 Received message Then, make the final connection decision and send the decision message. Send to the previous node N even .when Node N even+1 When available and its buffer is not full, At this time, node N even+1 With node N even Connection, N even Send the first data packet that arrives in the buffer queue, N. even+1 Upon receiving a data packet, it is temporarily stored in its own buffer; otherwise... At this time, node N even+1 Without any connection, the link remains in its original state. In an odd-numbered time slot j, if the i-th data packet arrives at node N1, the time slot at that moment is recorded as the time t when the i-th data packet began transmission. start (i);

[0039] Similarly, in the (j+1)th time slot (which is now an even time slot), each odd-numbered node N in the link odd(1≤odd≤K-1) to the next node N odd+1 Send message If the message is sent Represents the current node N odd Available and the current relay's buffer queue contains packets; if Indicates the current node N odd Unavailable or buffer full;

[0040] Each even-numbered node N odd+1 Received message Then, make the final connection decision and send the decision message. Send to the previous node. When Node N odd+1 When available and its buffer is not full, At this time, node N odd+1 With node N odd Connection, N odd Send the first data packet in the buffer queue, N. odd+1 Upon receiving a data packet, it is temporarily stored in the buffer; otherwise, At this time, node N odd+1 It does not connect to other nodes, and the link remains in its original state. In even-numbered time slot j+1, if the i-th data packet arrives at node N... K Record the time slot at this moment as the time t when the i-th data packet arrives at the destination. end (i).

[0041] Figure 3 and Figure 4 This paper investigates the impact of node occupancy probability and buffer size on system performance when transmitting 1000 data packets in a four-hop system consisting of one source, one destination, and three relays. Simulation results show that while increasing the buffer size increases latency, it improves system throughput. When the node occupancy probability is low, the system throughput performs well. Therefore, this method is suitable for systems with a low node occupancy probability and low latency sensitivity.

[0042] Figure 5 , Figure 6 The simulation results reflect the impact of the total number of data packets and different hop counts on system performance when the node occupancy probability Pk = 0.1 and the buffer size L = 3. The simulation results show that as the total number of data packets increases, the system gradually tends to a stable state. Although increasing the number of hops will lead to greater latency, the impact on throughput is relatively small, and the system throughput is basically maintained at a high level.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A distributed multi-hop buffer-assisted link selection method for low-Earth orbit satellites, characterized in that: The method includes: The transmission time is divided into multiple time slots of equal length, each time slot including node negotiation time and data packet transmission time; Establish a satellite communication model with buffer-assisted relay; By negotiating connections among nodes in the satellite communication model, multiple links can transmit simultaneously without interference, thus achieving distributed data transmission. The method includes the following steps: S1, initialize data information, divide time into an infinite number of equal-length time slots, and establish a connection between a source end, a destination end, and... Composed of several low-orbit satellites as relays Jump system, set The number is even; each relay is equipped with one storage. A buffer for each data packet; nodes in the system are marked as ,in, and Representing the source node, destination node, and relay node respectively. The probability of it being occupied is , The link between any two nodes is denoted as . ,common Link, ,Right now: and The link between them is , and The link between them is , ..., and The link between them is When node When occupied, the link connected to it and All interrupted; system transmits data. Each data packet carries a Bit information; S2, determine the current time slot. If it is an odd time slot, go to S3; if it is an even time slot, go to S4. S3, each even-numbered node in the link Next node Send message , If the message is sent , representing the current node The node is available and has data packets in the buffer. It can transmit and expects to connect to the next node; if , indicating the current node If the node is unavailable or has no data packets in its buffer, then the node... Unable to transmit; odd nodes Received message from the previous even-numbered node Then, make the final connection decision and send the decision message. Send to the previous node; when both of the following conditions are met: ,node When available and the buffer is not full. At this time, the node With nodes connect, Send the first data packet in the buffer queue. After receiving a data packet, it is temporarily stored in a buffer queue; otherwise, At this time, node Do not connect to the previous node; the node retains its original state. Record No. A data packet arrived at the node. The time slot is , This represents the time slot in which the data packet begins transmission; S4, each odd-numbered node in the link Next node Send message , If the message is sent , representing the current node If the node is available and there are packets in the buffer queue, then the node... It can transmit data and expects to connect to the next node; if , representing the current node If the node is unavailable or has no data packets in its buffer, then the node... Unable to transmit; Each even-numbered node Received message Then, make the final connection decision and send the decision message. Send to the previous node; when both of the following conditions are met: ,node When available and the buffer is not full. At this time, node With nodes Connections, nodes Send the first data packet in the buffer queue. After receiving a data packet, it is temporarily stored in a buffer queue; otherwise, At this time, node Do not connect to the previous node; the link remains in its original state. Judge the first Has the data packet arrived at the node? If yes, it indicates that the data packet has been successfully transmitted, and the corresponding time slot will be allocated. This is recorded as the time slot at which the data packet transmission ends; Step S5, determine If the data packet transmission is complete, proceed to step S2. If so, the transmission ends. Otherwise, go to step S2 until... One data packet has been transmitted; The odd-numbered time slots can only be transmitted via odd-numbered links, as observed by the nodes. The status of the nodes is used to determine whether data packets have been sent from the source; even-numbered time slots can only transmit on even-numbered links, which can be determined by observing the nodes. The status is used to determine whether the data packet has reached the destination.

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