Satellite on-demand access method and system based on conflict resolution in integrated space-ground network

Abstract

This invention provides a satellite on-demand access method and system based on conflict resolution in an integrated space-ground network, comprising: Step S1: The satellite terminal assembles source data packets to form an initial data frame and sends the initial data frame to the access satellite; Step S2: The satellite terminal waits for an ACK message sent by the access satellite; Step S3: The satellite terminal assembles and sends subsequent data frames; Step S4: The access satellite obtains the source data packets through decoding; Step S5: The access satellite sends an ACK message confirming the source data packets. This invention uses conflict resolution technology to restore conflict signals, overcoming the limitations of traditional schemes on global clock synchronization; and employs a partial retransmission mechanism after a conflict, shortening the channel occupancy time during retransmission, reducing the probability of re-collision, and further improving access performance. In most access scenarios and load conditions, satellite throughput is improved by more than 20%.

Description

Technical Field

[0001] This invention relates to the field of integrated space-ground networks, and more specifically, to a satellite access method and system based on conflict resolution in integrated space-ground networks. Background Technology

[0002] A key feature of integrated space-ground networks is their ability to support users to access satellites on demand and anywhere, truly achieving global communication coverage and providing information services anytime, anywhere. Therefore, providing random access is a fundamental function of integrated space-ground networks. However, when multiple users access the same satellite, signal conflicts between different users are inevitable. The receiving satellite may not be able to identify the correct information and therefore often chooses to discard these signals (e.g., ...). Figure 2 This caused the access to fail.

[0003] Terrestrial networks typically employ Carrier Sense Multiple Access (CSMA) to improve access success rates. This involves a node listening to the channel status before sending a data packet; if the channel is in use, it waits a period before attempting again. However, because the single-hop time of a satellite-to-ground link is much longer than that of a terrestrial network, CSMA incurs excessive time overhead, rendering it unusable. Furthermore, while random protocols like Aloha do not perform carrier sense, the collisions between randomly transmitted signals from multiple users are severe, resulting in extremely low efficiency; this phenomenon is even more pronounced in satellite communications with long link delays. Therefore, satellite access should be based on interference mitigation techniques, where the receiver recovers the original signal from the conflicting signals, fully utilizing the conflicting signals to reduce retransmissions and improve user access efficiency and system throughput.

[0004] During random access, frequent inter-user collisions severely limit the success rate of data transmission, becoming a bottleneck for network performance. Although interference cancellation techniques can utilize collisions to recover the original data packets, excessive signal collisions can also lead to extremely low interference cancellation performance.

[0005] The greater the amount of signal received by the satellite per unit time, the higher the probability of collision. This invention proposes an efficient collision resolution technique based on partial retransmission. When a data packet collides for the first time on the satellite side, the user end only sends a portion of the data packet. This significantly reduces the traffic volume in the access system and the time occupied by a single retransmission on the channel, thereby reducing the probability of concurrent signal collisions in the satellite channel and effectively mitigating the two fundamental causes of collisions.

[0006] Based on interference cancellation technology, the source signal of interference can be extracted from the conflict signals of multiple concurrent users, which has become an important support for providing random access services in space-ground integrated networks. However, existing solutions are difficult to effectively support efficient random access in satellite networks. Casini et al. (Enrico Casini, Riccardo De Gaudenzi, Oscar Del Rio Herrero. Contention resolution diversity slotted ALOHA (CRDSA): An enhanced random access scheme for satellite access packet networks. IEEE Transactions on Wireless Communications, 6(4), 2007) designed a CRDSA protocol for satellite networks. Within the transmission frame of the network, each user can randomly select two time slots to retransmit the data packet twice. Within one frame, each user can only send one data packet. The receiver performs continuous interference cancellation within one frame to recover as many data packets as possible, and the system throughput can reach up to 55%. Based on the CRDSA protocol framework, in order to improve the collision resolution rate, GianluigiLiva (Gianluigi Liva. Contention resolution diversity slotted aloha with variable rate burst repetitions. In GLOBECOM 2010:1-6, IEEE) proposed allowing each user to randomly select the number of copies of the data packets to be sent, further improving system throughput. However, these schemes all have an important prerequisite: the clocks of all user terminals must be globally synchronized to ensure frame synchronization and time slot synchronization; otherwise, the probability of collisions will increase significantly, which is difficult to achieve in a space-air-ground integrated network composed of a large number of independent users.

[0007] To eliminate dependence on the global clock, Cai et al. (Lei Zheng, Lin Cai. AFDA: Asynchronous flipped diversity ALOHA for emerging wireless networks with long and heterogeneous delay. IEEE Transactions on Emerging Topics in Computing, 3(1):64-73, 2015) designed an access protocol called AFDA. Its unique feature is that each data packet is organized into a super packet, where the second copy is a flip of the original data packet, and a flag bit is added to the beginning and end of the super packet. The super packet is then sent completely independently and randomly. Therefore, each data packet provides at least two copies for decoding, but the transmission time of each packet is effectively doubled, greatly increasing the probability of collisions. Ultimately, the number of data packets recovered through interference cancellation is limited, resulting in limited performance improvement.

[0008] This invention addresses two key factors limiting interference cancellation technology: the requirement for network-wide clock synchronization and frequent signal collisions. It uses collision resolution technology to restore conflicted signals, thus overcoming the limitations of traditional solutions on global clock synchronization. Furthermore, by employing a partial retransmission mechanism after a collision, it shortens the channel occupancy time during retransmission, reduces the probability of re-collision, and further improves access performance. Summary of the Invention

[0009] To address the shortcomings of existing technologies, the purpose of this invention is to provide a satellite access method and system based on conflict resolution in an integrated space-ground network.

[0010] A satellite on-demand access method based on conflict resolution in a space-ground integrated network, provided by the present invention, includes:

[0011] Step S1: The satellite terminal assembles the source data packets to form an initial data frame and sends the initial data frame to the access satellite;

[0012] Step S2: The satellite terminal waits for the ACK message and prepares for retransmission; the terminal waits for the satellite to acknowledge the data packet; each source data packet p i (1≤i≤N), the terminal only sends a portion of its packets during each retransmission. p i A portion of the bits; and a portion of the packet is regenerated before each retransmission;

[0013] Step S3: The satellite terminal assembles and sends subsequent data frames;

[0014] Step S4: The access satellite obtains the source data packet by decoding;

[0015] Step S5: Receive the ACK message confirming the source data packet sent by the access satellite.

[0016] Preferably, step S1 employs:

[0017] Step S1.1: The satellite terminal assembles an initial data frame F0 consisting of μ source data packets; where the source data packets are the original data groups in the file to be transmitted; if the file sent by the terminal contains N source data packets: {p1, p2, ..., p...} N}, for each source data packet p i (1≤i≤N), the satellite terminal sends its complete bits for the first time;

[0018] Step S1.2: The satellite terminal sends an initial data frame F0; where F0 consists of μ complete source data packets; the sending frame is maintained independently by each user; each data packet within the frame is sent randomly and does not require synchronization;

[0019] Step S1.3: Buffer the initial transmission frame F0; after transmission is complete, move the μ source data packets in F0 into the buffer.

[0020] Preferably, step S1.1 employs the following:

[0021] Step S1.1.1: Transmit frame structure; the transmit frame consists of μ data packets; each data packet within the frame includes a complete packet or a partial packet; each data packet ends with a raw data packet end bit. or partial packet end position A frame end marker is also set at the end of a frame;

[0022] A complete packet contains all the bits from the source data packet; a partial packet contains only a subset of the bits.

[0023] The initial transmission frame F0 consists of μ complete source data packets, with an end-of-packet bit added to the end of each source data packet. If the satellite at the receiving end detects the flag bit, then the data packet has ended;

[0024] In one transmission, F0 consists of μ source data packets, and other frames F i (i>1) consists of μ complete packets or partial packets, where unacknowledged data packets are replaced by partial packets;

[0025] Step S1.1.2: Determining the number of data packets μ in a transmission frame; The number of data packets μ in a transmission frame depends on the length of the received bit sequence decoded by the satellite and the number of bits in the source data packet;

[0026]

[0027] in, It is the number of bits received during satellite decoding. It is the number of bits in the source data packet.

[0028] Preferably, step S2 employs:

[0029] Step S2.1: Start the confirmation timeout; after the confirmation timeout t ACK Before arrival, the satellite terminal waits for a confirmation message from the satellite; the confirmation timeout is the longest time interval between when the terminal finishes sending the data packet and when it waits for the confirmation message for that data packet; the confirmation timeout t ACK The calculation is as follows:

[0030] t ACK =RTT+t reg (2)

[0031] Where RTT is the round-trip time between the terminal and the satellite; t reg The computation time for resolving the original signal from the conflict signal;

[0032] Step S2.2: Based on the confirmation message, determine whether the data packet needs to be retransmitted;

[0033] If in t ACK Previously, a request was received for source data packet p. i If p successfully confirms the ACK, then i Correctly received by the satellite, p removed from the buffer. i Proceed directly to step S3; otherwise, partial retransmission of p is required. i Proceed to step S2.3;

[0034] Step S2.3: Generate a partial package; if in t ACK Before the timeout, any data packet p is received. i (1≤i≤N) failure message NACK; or t ACK Time's up, but I haven't received p. i Any confirmation message from the packet will construct its partial packet.

[0035] Preferably, step S2.3 employs the following:

[0036] Step S2.3.1: Determine the length of the partial package; let k represent the ratio of the length of the partial package to the length of the complete package. in, and These represent the number of bits in a partial packet and the number of bits in a complete packet, respectively.

[0037] Step S2.3.2: Build a partial package The sending terminal randomly selects from the complete packet p i Extraction 1 bit, generating part

[0038] Preferably, step S3 employs the following methods:

[0039] Step S3.1: The satellite terminal assembles a subsequent data frame F consisting of μ partial packets / source data packets; for any partial packet / source data packet in the preceding transmitted frame, if the source data packet p is received... i If the ACK is received, the access satellite will correctly parse p. i Then the p in the preceding frame will be sent. i With subsequent new source data packets p in the file j Replace; otherwise, p in subsequent transmitted frames F i The corresponding position to generate a partial package Substitute;

[0040] The newly generated data frame F includes the newly inserted, unsent complete data packet p. j and data packets p that were sent but not successfully decoded i Partial package

[0041] Step S3.2: After waiting for a random period of time, send the subsequent data frame F; each terminal randomly selects a random time and independently sends the newly assembled transmission frame F; at the same time, insert the newly inserted complete data packet p into F. j Move into the buffer;

[0042] Repeat this process until N source data packets p are reached. i If all ACK messages for (1≤i≤N) are received, the transmission process is successfully completed.

[0043] Preferably, step S4 employs the following methods:

[0044] Step S4.1: Block-based decoding structure. When multiple users compete for satellite network, the satellite continuously receives conflicting signals. The limited satellite memory cannot store all received bit sequences of certain data packets for decoding. When data packets are retransmitted multiple times, only a certain length of signal can be stored for decoding each time.

[0045] After the current block is fully decoded, its space is released, the decoding window is moved forward, the subsequently received bits are stored, and a new round of decoding begins.

[0046] Step S4.2: Decode the conflicted data packet, including identifying non-conflicting bits and parsing conflicting bits.

[0047] Preferably, step S4.2 includes:

[0048] Step S4.2.1: Identification of the data packet to which the signal belongs; the terminal sends data in frames, and each data packet ends with an end marker; if the satellite detects this marker, then the data packet has ended;

[0049] Step S4.2.2: Data packet decoding; In the decoding structure block, separate the non-collision bits, and based on the data frame structure, identify the data packet to which the bit belongs and its position in other data packets; Then, through the non-collision bits, parse out all relevant collision bits; This parsing process will be iterated repeatedly until all relevant collision bits are parsed out, or the maximum number of iterations has been reached.

[0050] Preferably, step S5 employs the following methods:

[0051] Step S5.1: Send a decoding success message ACK; when a data packet is completely recovered, the satellite receiver returns an acknowledgment message ACK to the user; the terminal receives data packet p i After the ACK, it indicates that p i If the data packet p has been successfully received, the terminal removes it from its buffer. i ;

[0052] Step S5.2: Send a decoding failure message NACK; When there is insufficient semaphore, some data packets cannot be successfully decoded. In this case, the satellite sends a failure acknowledgment NACK.

[0053] According to the present invention, a high-efficiency satellite on-demand access system based on conflict resolution in a space-ground integrated network includes:

[0054] Module M1: Randomly constructs partial packets to generate a data frame F consisting of μ partial packets or a complete data packet;

[0055] Module M2: Responsible for sending data frames, receiving acknowledgment messages, and managing buffers and timers;

[0056] Module M3: Performs conflict resolution;

[0057] Module M4: Sends an acknowledgment message based on the conflict resolution results;

[0058] Modules M1 and M2 are installed on the terminal side, and modules M3 and M4 are installed on the access satellite side;

[0059] Specifically, module M1 adopts:

[0060] Module M1.1: Based on the acknowledgment message, determines whether to generate a partial packet; if in t ACK Before the timeout, any data packet p is received. i A failure message NACK for (1≤i≤N); or t ACKTime's up, but I haven't received p. i Any confirmation message from the packet will construct its partial packet.

[0061] Determine the length of the partial packet, denoted by k, which represents the ratio of the partial packet length to the complete packet length. in, and These represent the number of bits in a partial packet and the number of bits in a complete packet, respectively.

[0062] Build partial packages The sending terminal randomly selects from the complete packet p i Extraction 1 bit, generating part

[0063] Module M1.2: Assembles a data transmission frame consisting of μ data packets; each data packet within the frame includes a complete packet and a partial packet; each data packet ends with a raw data packet end bit. or partial packet end position A frame end marker is also set at the end of a frame;

[0064] The initial transmission frame F0 consists of μ complete source data packets; when assembling subsequent data frames F, for any part of the packet / source data packet in the preceding transmission frame, if the source data packet p is received... i The satellite correctly resolved the ACK confirmation. i Then the p in the preceding frame will be sent. i With subsequent new source data packets p in the file j Replace; otherwise, p in F i The corresponding position to generate a partial package Substitute;

[0065] The module M2 adopts:

[0066] Module M2.1: Each terminal randomly selects a random time and independently sends the newly assembled data frame F;

[0067] Module M2.2: After the initial data frame F0 and subsequent data frames F are sent, they are moved into the buffer;

[0068] Module M2.3: Responsible for maintaining the time the terminal waits for an acknowledgment message from the access satellite; acknowledgment timeout is the longest time interval between when the terminal finishes sending a data packet and when it waits for an acknowledgment message for that data packet;

[0069] Module M2.4: Receives acknowledgment messages from the access satellite; if at t ACK Previously, a request was received for source data packet p. i If p successfully confirms the ACK, then iCorrectly received by the satellite, p removed from the buffer. i Otherwise, perform partial retransmission.

[0070] The module M3 adopts:

[0071] Module M3.1: Identifies non-collision bits and their positions; the terminal sends data in frames, with an end marker at the end of each data packet; if the satellite detects this marker, the data packet has ended;

[0072] Module M3.2: Iteratively parses conflicting bits to generate corresponding acknowledgment messages and sends them to the terminal; it also parses out all relevant conflicting bits using non-conflicting bits.

[0073] The module M4 adopts:

[0074] Module M4.1: Constructs an acknowledgment message based on the conflict resolution results; generates an ACK message when a data packet is fully recovered; otherwise, generates a NACK message.

[0075] Module M4.2: Sends the source data packet p to the terminal. i Confirmation message.

[0076] Compared with the prior art, the present invention has the following beneficial effects:

[0077] 1. The satellite access side uses conflict decoding technology, which eliminates the need for clock synchronization between independent satellite users, allowing users to access satellites at any time;

[0078] 2. The partial retransmission mechanism after a collision significantly reduces the probability of another collision, reduces network load, and thus increases network throughput by more than 20%. Attached Figure Description

[0079] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0080] Figure 1 This is a flowchart of the satellite access method based on conflict resolution in this invention.

[0081] Figure 2 This is a schematic diagram illustrating multiple satellite users competing for access to the same satellite in an embodiment of the present invention.

[0082] Figure 3 This refers to the data frames sent by the satellite terminal in this embodiment of the invention.

[0083] Figure 4 This is a schematic diagram illustrating the random generation of some packages in an embodiment of the present invention.

[0084] Figure 5This is a schematic diagram of the parsing process of two conflicting data packets in an embodiment of the present invention.

[0085] Figure 6 This refers to the data packet state transition in this embodiment of the invention.

[0086] Figure 7 This is a block diagram of the satellite random access system based on conflict resolution in an embodiment of the present invention. Detailed Implementation

[0087] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0088] The target environment of this invention is random satellite access in a space-ground integrated network, such as... Figure 2 As shown, within satellite coverage, multiple ground users compete to access the same satellite channel. These users are independent and geographically distant, making global clock synchronization difficult to achieve; the propagation time between users and satellites is prolonged, and channel eavesdropping costs are too high, resulting in extremely low efficiency of traditional terrestrial wireless access protocols. To support global coverage and ubiquitous access in integrated space-ground networks, satellite access methods must be independent of clock synchronization and allow users to access satellites completely randomly.

[0089] This invention addresses the space-to-ground link hop from the ground to the satellite network, focusing on application scenarios where multiple ground users share access to a single satellite channel (e.g., Figure 2 (Three users concurrently access the same satellite). Addressing the problems of existing wireless access technologies in satellite access, this invention provides a satellite on-demand access method and system based on conflict resolution in an integrated space-ground network.

[0090] Conflict resolution technology allows the sender to continuously transmit before receiving an acknowledgment message, avoiding long waiting times for the access terminal, making it particularly suitable for satellite access scenarios with long propagation delays. However, frequent signal collisions between multiple users can also lead to repeated retransmissions by the terminal. Therefore, reducing signal collisions is crucial during independent, random satellite access by the terminal. This invention addresses this by transmitting each data packet in its entirety only the first time. If a collision occurs on the satellite side, the terminal will only randomly transmit a portion of the data packet during subsequent retransmissions. This effectively shortens the channel occupancy time and reduces the actual system load. Both of these aspects effectively reduce the probability of multi-channel signal collisions and the number of terminal retransmissions on the satellite access side, thereby improving the throughput of the satellite-to-ground link.

[0091] Example 1

[0092] This invention provides a satellite on-demand access method and system based on conflict resolution in an integrated space-ground network, which has the following advantages: First, the conflict resolution-based access method does not require terminal channel detection, completely eliminating the dependence on clock synchronization. Second, by resolving conflicting bits among multiple users on the access satellite side, the sending end is allowed to continuously send subsequent data packets before receiving a data packet acknowledgment message. Third, when a data packet is colliding, the terminal randomly retransmits a portion of its bits (generally 25% to 50%), which not only reduces system traffic but also achieves a higher decoding rate than retransmitting the complete data packet.

[0093] Specifically, according to the present invention, a satellite access method based on conflict resolution in an integrated space-ground network is provided, such as... Figure 1 As shown, it includes:

[0094] Step S1: The satellite terminal assembles and sends the initial data frame. Due to the extended propagation time of the satellite-to-ground link, the time the terminal waits for ACK is much longer than the transmission delay of the data packets; at the same time, the single data packet transmission mechanism results in a lack of sufficient copies during satellite-side decoding, thus affecting decoding efficiency. To solve the problems of extended successful transmission time and insufficient copies, this invention uses a frame as a basic transmission unit, that is, the terminal sends a data frame composed of multiple data packets at a time.

[0095] Step S2: The satellite terminal waits for the ACK message and prepares for retransmission. The terminal waits for the satellite's acknowledgment of the data packets. Each source data packet p i (1≤i≤N), the terminal only sends a portion of its packets during each retransmission. That is, p i A portion of the bits; and before each retransmission, a portion of the packet is regenerated.

[0096] Step S3: The satellite terminal assembles and sends subsequent data frames.

[0097] Step S4: The access satellite obtains the source data packet by decoding.

[0098] Step S5: Access satellite sends source data packet p i Confirmation message.

[0099] For example: Figure 6 As shown, for any data packet p i Its status changes during transmission as follows: Send → Buffer → Decode → Success. Details are as follows:

[0100] "Send": When the user sends p i When loading a data frame and transmitting it to the satellite at a randomly selected time, p iThe current state; at this point, a complete data packet must be sent to ensure that the satellite receives all transmitted bits.

[0101] "Buffer": When p i When the data frame is sent, p i If it is moved into the buffer, then p i The terminal enters a "buffering" state. At this time, the terminal waits for satellite input to p. i Confirmation;

[0102] If an ACK is received, then p i Remove from buffer, p i Entering "success" status;

[0103] If a NACK is received, generate a partial packet. Resend.

[0104] "Decoding": When p i Before successful decoding on the satellite side, p i On the satellite side, enter the "decoding" state. If decoding is successful, send an ACK; otherwise, send a NACK.

[0105] "Success": When the terminal receives a response to p i The ACK message is removed from the buffer, p i Successfully entered the "successful" state.

[0106] The file is successfully transmitted when all data packets for a file enter the "success" state.

[0107] Specifically, step 1 employs the following:

[0108] Step S1.1: The terminal assembles an initial data frame F0 consisting of μ source data packets. The source data packets are the original data blocks in the file to be transmitted. If the file sent by the terminal contains N source data packets: {p1, p2, ..., p...} N}, for each source data packet p i (1≤i≤N), the terminal sends its complete bits for the first time.

[0109] Step S1.1.1: Send frame structure. For example... Figure 3 As shown, a transmission frame consists of μ data packets; each data packet within the frame may be a complete packet or a partial packet; each data packet ends with a packet end flag. (End bit of original data packet) or (Partial packet end bit); A frame end flag is also set at the end of a frame.

[0110] The initial transmission frame F0 consists of μ complete source data packets, with an end-of-packet bit added to the end of each source data packet. (End of packet). The receiving satellite detects these flags and considers the data packet to have ended.

[0111] In one transmission, F0 consists of μ source data packets, and other frames F i (i>1) consists of μ complete packets or partial packets, where unacknowledged data packets are replaced by partial packets.

[0112] Step S1.1.2: Determining the number of data packets μ in a transmission frame. The number of data packets μ in a transmission frame depends on the length of the received bit sequence that can be decoded by the satellite and the number of bits in the source data packet, i.e.

[0113]

[0114] in It is the number of received bits that the satellite can decode. It is the number of bits in the source data packet.

[0115] Step S1.2: The terminal sends the initial data frame F0. Clearly, F0 consists of μ complete source data packets. Each user maintains its own frame independently; data packets within the frame are sent randomly and do not require synchronization.

[0116] Step S1.3: Buffer the initial transmission frame F0. After transmission is complete, move the μ source data packets in F0 into the buffer.

[0117] Specifically, step S2 employs the following:

[0118] Step S2.1: Start the confirmation timeout. The confirmation timeout t... ACK Before arrival, the terminal waits for a satellite acknowledgment message. The acknowledgment timeout is the longest time interval between when the terminal completes sending a data packet and when it waits for an acknowledgment message for that data packet. Acknowledgment timeout t ACK The timeout of ACK is calculated as follows:

[0119] t ACK =RTT+t reg (2)

[0120] Where RTT is the round-trip time between the terminal and the satellite; t reg The computation time for regeneration is used to extract the original signal from the conflict signal.

[0121] Step S2.2: Based on the confirmation message, determine whether the data packet needs to be retransmitted.

[0122] If in t ACK Previously, a request was received for source data packet p. iThe successful confirmation ACK means that p i If the signal is correctly received by the satellite, remove p from the buffer. i If so, skip step S2.3 and proceed directly to step S3; otherwise, partial retransmission of p is required. i Proceed to step S2.3.

[0123] Step S2.3: Generate a partial package. If in t ACK Before the timeout, any data packet p is received. i (1≤i≤N) failure message NACK; or t ACK Time's up, but I haven't received p. i Any confirmation message from the packet will construct its partial packet.

[0124] Specifically, part of step S2.3 includes The generation is as follows:

[0125] Step S2.3.1: Determine the length of the partial packet. Let k represent the ratio of the partial packet length to the complete packet length, i.e.: in, and These represent the number of bits in a partial packet and the number of bits in a complete packet, respectively. Test results show that, under most satellite scenarios and load conditions, the overall network decoding performance is high when k = 0.25–0.5.

[0126] Step S2.3.2: Build a partial package like Figure 4 As shown, the sending terminal randomly selects from the complete packet p i Extraction 1 bit, generating part

[0127] Specifically, step S3 employs the following:

[0128] Step S3.1: The terminal assembles the subsequent data frame F from μ partial packets / source data packets. For any partial packet / source data packet in the preceding transmitted frame (the first frame is F0), if the source data packet p is received... i ACK confirmation, meaning the satellite correctly resolved p i Then the p in the preceding frame will be sent. i With subsequent new source data packets p in the file j (i.e., p) μ+1 p μ+2 ...) replace. Otherwise, p in the subsequent transmitted frame F i The corresponding position is the partial package generated in step S2.3. Replacement.

[0129] In this way, the newly generated data frame F contains both the newly inserted, unsent complete data packet p. j There are also data packets p that have been sent but not successfully decoded. i Partial package

[0130] Step S3.2: After waiting for a random period of time, send the subsequent data frame F. Each terminal randomly selects a random time and independently sends the newly assembled transmission frame F. Simultaneously, the newly inserted complete data packet p in F is... j Move into the buffer.

[0131] The above steps S2-S3 are repeated until N source data packets p are obtained. i If all ACK messages for (1≤i≤N) are received, the transmission process is successfully completed.

[0132] Specifically, step S4 employs the following:

[0133] Step S4.1: Block-based decoding structure. When multiple users compete for a satellite network, the satellite continuously receives conflicting signals. Limited satellite memory cannot store all the received bit sequences of certain data packets for decoding; especially when data packets are retransmitted multiple times, only a certain length of signal can be stored for decoding each time. Therefore, this invention employs a block-based decoding mechanism on the satellite side, storing a certain length of received bit sequence for the decoding process, referred to as a "block".

[0134] After the current block is fully decoded, its space is released, the decoding window is moved forward, the subsequently received bits are stored, and a new round of decoding begins.

[0135] Step S4.2: Decode the conflicting data packet.

[0136] Step S4.2.1: Identification of the data packet to which the signal belongs. The terminal sends data in frames, and each data packet ends with an end marker. The satellite detects this marker and considers the data packet to have ended. Therefore, regardless of whether the received signals collide, by detecting the marker, it is possible to identify which specific source data packet p any given bit belongs to. i .

[0137] Step S4.2.2: Data packet decoding. First, non-collision bits are separated from the decoding structure "block". Based on the data frame structure designed in this invention, the data packet to which the bit belongs and its position in other data packets can be easily identified. Then, all relevant collision bits are parsed through the non-collision bits. This parsing process will be iterated repeatedly until all relevant collision bits are parsed, or the maximum number of iterations has been reached.

[0138] exist Figure 5In the first transmission, each user's complete data packet is 4 bits long. Besides, the remaining 6 bits conflicted. In the second transmission, the two users sent 3 and 2 bits respectively, and... No conflict. With these signals (among others) and (No conflict), the satellite decoding process is as follows: in addition Therefore, two source data packets were decoded.

[0139] Specifically, step S5 employs the following:

[0140] Step S5.1: Send a decoding success message (ACK). Once a data packet is fully recovered, the satellite receiver returns an ACK message to the user. The terminal receives data packet p. i After the ACK, it indicates that p i If the data packet p has been successfully received, the terminal removes it from its buffer. i At this point, the workflow proceeds to step S2.2.

[0141] Step S5.2: Send a decoding failure message (NACK). When there is insufficient semaphore, some data packets cannot be successfully decoded, meaning that the parsing process in step S4.2.2 has exceeded the maximum number of iterations and some bits are still unparsed. In this case, the satellite sends a failure acknowledgment (NACK). At this point, the workflow also proceeds to step S2.2.

[0142] According to the present invention, a satellite access system based on conflict resolution in a space-ground integrated network is provided, such as... Figure 7 As shown, it includes:

[0143] Module M1: Randomly constructs partial packets to generate a data frame F consisting of μ partial packets or a complete data packet;

[0144] Module M2: Responsible for sending data frames, receiving acknowledgment messages, and managing buffers and timers;

[0145] Module M3: Performs conflict resolution;

[0146] Module M4: Sends an acknowledgment message based on the conflict resolution results;

[0147] The M1 and M2 modules are installed on the terminal side, such as on a satellite mobile phone. The M3 and M4 modules are installed on the satellite access side.

[0148] Specifically, module M1 adopts:

[0149] Module M1.1: Based on the acknowledgment message, determines whether to generate a partial packet. If in t ACKBefore the timeout, any data packet p is received. i A failure message NACK for (1≤i≤N); or t ACK Time's up, but I haven't received p. i Any confirmation message shall be constructed in part as follows:

[0150] Determine the length of the partial packet. Let k represent the ratio of the partial packet length to the complete packet length, i.e.: in, and These represent the number of bits in a partial packet and the complete packet, respectively. Test results show that under most satellite scenarios and workloads, decoding performance is high when k = 0.25–0.5.

[0151] Build partial packages like Figure 4 As shown, the sending terminal randomly selects from the complete packet p i Extraction 1 bit, generating part

[0152] Module M1.2: Assembles a data transmission frame consisting of μ data packets. Each data packet within the frame may be a complete packet or a partial packet; each data packet ends with a packet end flag. (End bit of original data packet) or (Partial packet end bit); A frame end flag is also set at the end of a frame.

[0153] The initial transmission frame F0 consists of μ complete source data packets. When assembling subsequent data frames F, for any part of the packets / source data packets in the preceding transmission frame (the first frame is F0), if the source data packet p is received... i ACK confirmation, meaning the satellite correctly resolved p i Then the p in the preceding frame will be sent. i With subsequent new source data packets p in the file j Replace; otherwise, p in F i The corresponding position is the partial package generated in step S2.3. Replacement. Thus, the newly generated data frame F contains both the newly inserted, unsent complete data packet p. j There are also data packets p that have been sent but not successfully decoded. i Partial package

[0154] Specifically, module M2 adopts:

[0155] Module M2.1: Each terminal randomly selects a random time to independently send the newly assembled data frame F.

[0156] Module M2.2: After the initial data frame F0 and subsequent data frames F are sent, they are moved into the buffer.

[0157] Module M2.3: Responsible for maintaining the time the terminal waits for an acknowledgment message from the access satellite. The acknowledgment timeout is the longest time interval between when the terminal completes sending a data packet and when it waits for an acknowledgment message for that data packet. Acknowledgment timeout t ACK (timeout of ACK) is calculated by formula (2).

[0158] Module M2.4: Receives acknowledgment messages from the access satellites. If in t ACK Previously, a request was received for source data packet p. i The successful confirmation ACK means that p i If the signal is correctly received by the satellite, remove p from the buffer. i Otherwise, call module M1.1 to perform partial retransmission.

[0159] Specifically, module M3 adopts:

[0160] Module M3.1: Identifies non-collision bits and their positions. The terminal transmits data in frames, each data packet ending with a marker. The satellite detects this marker and considers the data packet to have ended. Therefore, regardless of whether the received signals collide, the satellite can easily distinguish which specific source data packet p any given bit belongs to by detecting the marker. i .

[0161] Module M3.2: Iteratively parses conflicting bits to generate corresponding acknowledgment messages and sends them to the terminal. It parses all relevant conflicting bits using non-conflicting bits. For example, in... Figure 5 In China, based on It can be parsed Then analyze them sequentially. and Similarly, from It can be parsed This process will be repeated iteratively until all relevant conflicting bits are resolved, or the maximum number of iterations has been reached.

[0162] Specifically, module M4 adopts:

[0163] Module M4.1: Constructs acknowledgment messages based on the conflict resolution results. An acknowledgment message (ACK) is generated when a data packet is fully recovered; otherwise, a failure message (NACK) is generated.

[0164] Module M4.2: Sends the source data packet p to the terminal. i Confirmation message.

[0165] Example 2

[0166] Example 2 is a preferred example of Example 1.

[0167] A satellite on-demand access method based on conflict resolution in a space-ground integrated network, provided by the present invention, includes:

[0168] Step S1: The satellite terminal assembles the source data packets to form an initial data frame and continuously sends the initial data frame to the access satellite;

[0169] Step S2: After sending is complete, move the current source data packet into the buffer area;

[0170] Step S3: Access the satellite to receive the current data frame and obtain the source data packet by decoding;

[0171] Step S4: The satellite sends an acknowledgment message and / or a failure message to the satellite terminal to confirm the transmission of the source data packet; when the satellite terminal reaches the acknowledgment timeout t ACK If an acknowledgment message for the source data packet arrives before the packet is received, the corresponding source data packet is removed from the buffer. If the satellite terminal receives a source data packet transmission failure message or the acknowledgment timeout occurs, the corresponding source data packet is removed from the buffer. ACK Upon arrival, if an acknowledgment message is received for the source data packet, a source data portion packet is generated based on the current corresponding source data packet.

[0172] Step S5: Generate a new data frame based on the current source data packet and the new source data packet;

[0173] Step S6: Send the new data frame to the access satellite, and repeat steps S2 to S6 until the preset number of source data packets are successfully transmitted.

[0174] This invention uses collision resolution technology to restore conflicted signals, overcoming the limitations of traditional schemes on global clock synchronization. A partial retransmission mechanism after a collision shortens the channel occupancy time during retransmission, reduces the probability of further collisions, and further improves access performance. In most access scenarios and load conditions, satellite throughput is improved by more than 20%.

[0175] Specifically, a packet end flag is set at the end of each source data packet; a frame end flag is set at the end of each data frame; the receiving satellite determines whether the current source data packet or data frame has ended transmission based on the packet end flag or the frame end flag.

[0176] Specifically, the number of source data packets in a data frame depends on the length of the received bit sequence decoded by the satellite and the number of bits in the source data packets;

[0177]

[0178] in, This indicates the number of received bits for satellite decoding; This indicates the number of bits in the source data packet.

[0179] Specifically, step S3 employs the following: the satellite terminal uses a block decoding mechanism to decode conflicting data packets; this includes: identifying non-conflicting bits and parsing conflicting bits; once the current block is fully decoded, the current block space is released, the subsequently received bits are stored, and a new round of decoding is performed.

[0180] Specifically, step S3 involves the satellite terminal sending data in frames, with each source data packet ending with an end marker. When the satellite detects the end marker, the current data packet has ended. The source data packet corresponding to any bit is identified by detecting the marker bit.

[0181] In the decoding structure block, non-collision bits are separated. Based on the data frame structure, the source data packet to which the current bit belongs and the position of the current bit in the source data packet are identified. All related collision bits are parsed from the non-collision bits. This process is repeated until all related collision bits are parsed or the maximum number of iterations is reached.

[0182] Specifically, the confirmation timeout t ACK use:

[0183] t ACK =RTT+t reg

[0184] Where RTT represents the round-trip time between the terminal and the satellite; t reg This represents the computation time required to extract the original signal from the conflict signal.

[0185] Specifically, the source data packet is generated by the satellite terminal randomly extracting a preset number of bits from the current corresponding source data packet.

[0186] According to the present invention, a satellite on-demand access system based on conflict resolution in a space-ground integrated network includes:

[0187] Module M1: The satellite terminal assembles the source data packets to form an initial data frame and continuously sends the initial data frame to the access satellite;

[0188] Module M2: After sending, move the current source data packet into the buffer.

[0189] Module M3: Receives the current data frame from the satellite and obtains the source data packet through decoding;

[0190] Module M4: Receives acknowledgment messages and / or failure messages for the source data packets sent by the satellite to the satellite terminal; when the satellite terminal experiences an acknowledgment timeout t... ACKIf an acknowledgment message for the source data packet arrives before the packet is received, the corresponding source data packet is removed from the buffer. If the satellite terminal receives a source data packet transmission failure message or the acknowledgment timeout occurs, the corresponding source data packet is removed from the buffer. ACK Upon arrival, if an acknowledgment message is received for the source data packet, a source data portion packet is generated based on the current corresponding source data packet.

[0191] Module M5: Generates a new data frame based on the current source data packet and the new source data packet;

[0192] Module M6: Sends new data frames to the access satellite, repeatedly triggering modules M2 to M6 until a preset number of source data packets are successfully transmitted.

[0193] This invention uses collision resolution technology to restore conflicted signals, overcoming the limitations of traditional schemes on global clock synchronization. A partial retransmission mechanism after a collision shortens the channel occupancy time during retransmission, reduces the probability of further collisions, and further improves access performance. In most access scenarios and load conditions, satellite throughput is improved by more than 20%.

[0194] Specifically, a packet end flag is set at the end of each source data packet; a frame end flag is set at the end of each data frame; the receiving satellite determines whether the current source data packet or data frame has ended transmission based on the packet end flag or the frame end flag.

[0195] Specifically, the number of source data packets in a data frame depends on the length of the received bit sequence decoded by the satellite and the number of bits in the source data packets;

[0196]

[0197] in, This indicates the number of received bits for satellite decoding; This indicates the number of bits in the source data packet.

[0198] Specifically, module M3 employs a block-based decoding mechanism to decode conflicting data packets, including identifying non-conflicting bits and parsing conflicting bits. Once the current block is fully decoded, the current block space is released, and subsequently received bits are stored for a new round of decoding.

[0199] Specifically, module M3 employs the following method: the satellite terminal transmits data in frames, each source data packet ends with an end marker, and when the satellite detects the end marker, the current data packet has ended; by detecting the marker bit, the source data packet corresponding to any bit can be identified.

[0200] In the decoding structure block, non-collision bits are separated. Based on the data frame structure, the source data packet to which the current bit belongs and the position of the current bit in the source data packet are identified. All related collision bits are parsed from the non-collision bits. This process is repeated until all related collision bits are parsed or the maximum number of iterations is reached.

[0201] Specifically, the confirmation timeout t ACK use:

[0202] t ACK =RTT+t reg

[0203] Where RTT represents the round-trip time between the terminal and the satellite; t reg This represents the computation time required to extract the original signal from the conflict signal.

[0204] Specifically, the source data packet is generated by the satellite terminal randomly extracting a preset number of bits from the current corresponding source data packet.

[0205] Those skilled in the art will understand that, in addition to implementing the system, apparatus, and their modules provided by this invention in purely computer-readable program code, the same program can be implemented in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, the system, apparatus, and their modules provided by this invention can be considered a hardware component, and the modules included therein for implementing various programs can also be considered structures within the hardware component; alternatively, modules for implementing various functions can be considered both software programs implementing the method and structures within the hardware component.

[0206] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A satellite on-demand access method based on conflict resolution in a space-ground integrated network, characterized in that, include: Step S1: The satellite terminal assembles source data packets to form an initial data frame. The initial data frame consists of μ complete source data packets. Each data packet in the frame is sent randomly and does not require global clock synchronization. The satellite terminal sends the initial data frame F0 to the access satellite and moves the μ source data packets in the initial data frame into the buffer. Step S2: The satellite terminal activates the confirmation timeout timer, and the confirmation timeout t... ACK Before arrival, wait for an acknowledgment message from the access satellite; for each source data packet p i， Where 1≤i≤N, if no successful ACK message is received, or a transmission failure message NACK message is received, or no acknowledgment message is received after the acknowledgment timeout, the satellite terminal prepares for retransmission by regenerating a portion of the source data packet before each retransmission. The portion package Only contains source data packet p i Part of the bits; where t ACK =RTT+t reg RTT is the round-trip time between the terminal and the satellite, t reg The computation time for resolving the original signal from the conflict signal; Step S3: The satellite terminal assembles subsequent data frames, which consist of μ complete source data packets or partial packets. The structure involves replacing source packets that have received ACK messages with new complete source packets, and replacing source packets that have not received ACK messages with partial packets. After waiting for a random period of time, the satellite terminal independently sends the subsequent data frame and moves the new complete source data packet in the subsequent data frame into the buffer. Step S4: The access satellite recovers the source data packet from the conflict signal by identifying non-conflicting bits and iteratively parsing conflicting bits; Step S5: The access satellite sends an acknowledgment message to the satellite terminal. If the source data packet is successfully recovered, an ACK message is sent. After receiving the ACK message, the satellite terminal removes the corresponding source data packet from the buffer. If the recovery is unsuccessful, a NACK message is sent. Repeat steps S2 to S5 until all source data packets have received ACK messages, at which point the transmission is complete.

2. The satellite access method based on conflict resolution in an integrated space-ground network according to claim 1, characterized in that, Step S1 adopts the following: Step S1.1: The source data packets are the original data blocks in the file to be transmitted; if the file sent by the terminal contains N source data packets: For each source data packet The satellite terminal sends its complete bits for the first time; ; Step S1.2: During the process of the satellite terminal sending the initial data frame, the sending frame is maintained independently by each user.

3. The satellite access method based on conflict resolution in an integrated space-ground network according to claim 2, characterized in that, Step S1.1 adopts the following: Step S1.1.1: Each data packet within a frame includes a complete packet or a partial packet; each data packet ends with a raw data packet end bit. or partial packet end position A frame end marker is also set at the end of a frame. A complete packet contains all the bits from the source data packet; a partial packet contains only a subset of the bits. Initial transmission frame It consists of μ complete source data packets, with a packet end bit added to the end of each source data packet. If the receiving satellite detects the flag, the data packet has ended. During a transmission, It consists of μ source data packets, and other frames It consists of μ complete packets or partial packets, where unacknowledged data packets are replaced by partial packets; where i>1; Step S1.1.2: Determining the number of data packets μ in a transmission frame; The number of data packets μ in a transmission frame depends on the length of the received bit sequence decoded by the satellite and the number of bits in the source data packet; (1) in, It is the number of bits received during satellite decoding. It is the number of bits in the source data packet.

4. The efficient satellite on-demand access method based on conflict resolution in a space-ground integrated network according to claim 1, characterized in that, Step S2 employs the following: Step S2.1: Start the confirmation timeout; after the confirmation timeout... Before arrival, the satellite terminal waits for a confirmation message from the satellite; confirmation timeout is the longest time interval between when the terminal finishes sending a data packet and when it waits for a confirmation message for that data packet; confirmation timeout The calculation is as follows: (2) RTT stands for round-trip time between the terminal and the satellite. The computation time for resolving the original signal from the conflict signal; Step S2.2: Based on the confirmation message, determine whether the data packet needs to be retransmitted; If in Previously, received the source data packet If the ACK is successfully confirmed, then Correctly received by the satellite and removed from the buffer. Proceed directly to step S3; otherwise, partial retransmission is required. Proceed to step S2.3; Step S2.3: Generate a partial package; if in If any data packet is received before the timeout period expires. The sending failed message NACK; or Time's up, but I haven't received it. Any confirmation message from the packet will construct its partial packet. ;in, .

5. The efficient satellite on-demand access method based on conflict resolution in a space-ground integrated network according to claim 4, characterized in that, Step S2.3 adopts the following: Step S2.3.1: Determine the length of part of the package; k This represents the ratio of the partial package length to the complete package length. = ,in, and These represent the number of bits in a partial packet and the number of bits in a complete packet, respectively. Step S2.3.2: Build a partial package The sending terminal randomly selects from the complete packet. Extraction 1 bit, generating part .

6. The efficient satellite on-demand access method based on conflict resolution in a space-ground integrated network according to claim 1, characterized in that, Step S3 employs the following: Step S3.1: Satellite terminal assembly by Each partial packet / source data packet constitutes a subsequent data frame F; for any partial packet / source data packet in the preceding transmitted frame, if the source data packet is received... If the ACK is received, the access satellite will correctly parse the data. Then the preceding frame will be sent... With subsequent new source data packets in the file Replace; otherwise, in subsequent transmitted frames F The corresponding position to generate a partial package Substitute; The newly generated data frame F includes the newly inserted, unsent complete data packets. and data packets that were sent but not successfully decoded Partial package ; Step S3.2: After waiting for a random period of time, send the subsequent data frame F; each terminal randomly selects a random time and independently sends the newly assembled transmission frame F; at the same time, insert the newly inserted complete data packet into F. Move into the buffer; Repeat until N source packets are received. If all ACK messages are received, the transmission process is successfully completed; among them, 7. The efficient satellite on-demand access method based on conflict resolution in an integrated space-ground network according to claim 1, characterized in that, Step S4 employs the following: Step S4.1: Block-based decoding structure. When multiple users compete for a satellite network, the satellite continuously receives conflicting signals. The limited satellite memory cannot store all the received bit sequences of certain data packets for decoding. When data packets are retransmitted multiple times, only a certain length of signal can be stored for decoding each time. The satellite side adopts a block-based decoding mechanism to store a certain length of received bit sequence as a block for the decoding process. After the current block is fully decoded, its space is released, the decoding window is moved forward, the subsequently received bits are stored, and a new round of decoding begins. Step S4.2: Decode the conflicted data packet, including identifying non-conflicting bits and parsing conflicting bits.

8. The efficient satellite on-demand access method based on conflict resolution in an integrated space-ground network according to claim 7, characterized in that, Step S4.2 includes: Step S4.2.1: Identification of the data packet to which the signal belongs; the terminal sends data in frames, and each data packet ends with an end marker; the satellite detects the end marker bit, then the data packet has ended; Step S4.2.2: Data packet decoding; Separate non-collision bits from the block, and based on the data frame structure, identify the data packet to which the bit belongs and its position in other data packets; Then, use the non-collision bits to parse out all relevant collision bits; This parsing process will be iterated repeatedly until all relevant collision bits are parsed out, or the maximum number of iterations has been reached.

9. The efficient satellite on-demand access method based on conflict resolution in a space-ground integrated network according to claim 1, characterized in that, Step S5 employs the following: Step S5.1: Send a decoding success message ACK; when a data packet is completely recovered, the satellite receiver returns an acknowledgment message ACK to the user; the terminal receives the data packet. After the ACK, it indicates If the data packet has been successfully received, the terminal removes it from its buffer. ; Step S5.2: Send a decoding failure message NACK; When there is insufficient semaphore, some data packets cannot be successfully decoded, and the satellite sends a failure acknowledgment NACK.

10. A high-efficiency satellite on-demand access system based on conflict resolution in a space-ground integrated network, characterized in that, include: Module M1: Randomly constructs partial packages, generating data from... A data frame consisting of partial packets or a complete data packet; Module M2: Responsible for sending data frames, receiving acknowledgment messages, and managing buffers and timers; Module M3: Performs conflict resolution; Module M4: Sends an acknowledgment message based on the conflict resolution results; Modules M1 and M2 are installed on the terminal side, and modules M3 and M4 are installed on the access satellite side; Specifically, module M1 adopts: Module M1.1: Based on the confirmation message, determines whether to generate a partial packet; if in If any data packet is received before the timeout period expires. The failure message NACK; or Time's up, but I haven't received it. Any confirmation message from the packet will construct its partial packet. ;in, ; To confirm the timeout; Determine the length of part of the package, in order to k This represents the ratio of the partial package length to the complete package length. = ,in, and These represent the number of bits in a partial packet and the number of bits in a complete packet, respectively. The sending terminal randomly selects from the complete packet Extraction 1 bit, generating part ; Module M1.2: Assembles a data transmission frame consisting of μ data packets; each data packet within the frame includes a complete packet and a partial packet; each data packet ends with a raw data packet end bit. or partial packet end position A frame end marker is also set at the end of a frame. When assembling subsequent data frames F, for any part of the packet / source data packet in the preceding frame, if the source data packet is received... The satellite correctly resolved the ACK confirmation. Then the preceding frame will be sent... With subsequent new source data packets in the file Replace; otherwise, in subsequent data frames F The corresponding position to generate a partial package Substitute; The module M2 adopts: Module M2.1: Each terminal randomly selects a random time and independently sends the newly assembled subsequent data frame F; Module M2.2: Initial Data Frame After subsequent data frames F are sent, they are moved into the buffer; the initial data frame It consists of μ complete source data packets; Module M2.3: Responsible for maintaining the time the terminal waits for an acknowledgment message from the access satellite; acknowledgment timeout is the longest time interval between when the terminal finishes sending a data packet and when it waits for an acknowledgment message for that data packet; Module M2.4: Receives acknowledgment messages from the access satellites; if in Previously, received the source data packet If the ACK is successfully confirmed, then Correctly received by the satellite and removed from the buffer. Otherwise, perform partial retransmission. The module M3 adopts: Module M3.1: The terminal sends data in frames, with an end marker at the end of each data packet; if the satellite detects the end marker, the data packet has ended. Module M3.2: Iteratively parses conflicting bits to generate corresponding acknowledgment messages and sends them to the terminal; it also parses out all relevant conflicting bits using non-conflicting bits. The module M4 adopts: Module M4.1: Constructs an acknowledgment message based on the conflict resolution results; generates an ACK message when a data packet is fully recovered; otherwise, generates a NACK message. Module M4.2: Sends source data packets to the terminal Confirmation message.

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