A design method for application layer network coding in multipath transmission networks

Abstract

The present invention proposes an application layer network coding design method for multipath transmission networks, including: setting system parameters at the sending end according to transmission quality and requirements, including the maximum interval threshold, minimum packet loss rate threshold and change weight factor of Inter coding packets. Information packets are scheduled and transmitted on multiple paths, and each path independently generates Intra coding packets. After independently decoding each path, the receiving end summarizes the results to the total decoder and feeds back suggestions on changes in packet loss rate and the number of Inter coding packets. The sending end dynamically adjusts the generation and insertion strategy of Inter coding packets based on the feedback. The receiving end gives priority to decoding the earliest lost information packets and submits the decoded information packets in a timely manner. The present invention combines Intra coding and Inter coding, improves transmission quality and efficiency, reduces latency and packet loss rate, and ensures the timeliness and integrity of information. This method is suitable for real-time data transmission scenarios.

Description

Technical Field

[0001] The present invention belongs to the field of wireless communication standardization process, and in particular relates to an application layer network coding design method for a multipath transmission network. Background Art

[0002] With the rapid development of communication technology, emerging applications such as connected vehicle communications, remote sensing data collection, and control system communications have placed higher demands on the real-time, reliability, and efficiency of data transmission. Multipath transmission is an effective method to increase transmission rates and reduce transmission latency. However, traditional multipath transmission schemes (such as MPTCP) use multipath polling scheduling, which suffers from severe head-of-line blocking in scenarios with unstable channels. While intra coding technology in existing systems enhances the transmission reliability of a single path, it suffers from low efficiency, lack of inter-path coordination, and insufficient adaptability. As a result, the system cannot fully utilize the potential of multipath transmission and struggles to meet the requirements for data freshness and transmission latency.

[0003] While a complete system upgrade is an option, the cost of equipment replacement is enormous, and many older devices can still partially meet the requirements of the new system. Therefore, a more economical and practical approach is to optimize the existing system. This invention proposes introducing additional redundant information, namely "Inter-coded packets," at the transmitting end of the old system. This method can significantly improve transmission reliability and efficiency without significantly changing the existing system structure. Inter-coded packets can help the receiving end recover data packets lost during transmission, effectively reducing end-to-end latency, improving overall system reliability, and significantly reducing system modification costs. However, how to effectively design and implement the Inter-coding mechanism, as well as how to coordinate Intra-coding and Inter-coding in multipath networks, still require further research. Designing adaptive coding schemes is particularly important in dynamic and uncertain network environments. In addition, how to maximize the utilization of delayed feedback information to improve communication performance is also a key issue. Summary of the Invention

[0004] The present invention aims to provide an application-layer network coding design for multipath transmission networks. This design uses generation-based, lagged feedback information to determine whether new cross-path coding packets need to be added and calculate the number of cross-path coding packets that need to be added. This solves the technical problems of difficulty in parameter changes and high packet loss rates in existing multipath transmission frameworks.

[0005] In order to solve the above technical problems, the specific technical solutions of the present invention are as follows:

[0006] An application layer network coding design for multipath transmission networks includes the following steps:

[0007] Step 1: Before transmission begins, set system parameters based on previous transmission quality and transmission requirements, including: Inter coding packet coding maximum interval threshold L th , L th ≥2, Inter code packet change weight factor γ, γ>1, by adjusting the maximum interval threshold L of the code packet th And the variable weight factor γ realizes the adaptive adjustment of Inter coding packets to optimize transmission quality and efficiency;

[0008] Step 2: At the start of transmission, the sender initializes the number of Inter packets to be sent to zero. At the beginning of each generation, it obtains all the information packets to be transmitted in that generation and schedules and transmits them on multiple paths. Each path has its own encoder and decoder, independently generating Intra packets. Each Intra packet is a linear combination of all information packets and Inter packets after the previous Intra packet in that path. Before receiving feedback from the receiver, the sender will continue to send Inter packets after completing the established transmission task to ensure that all information packets in each generation can be successfully decoded.

[0009] Step 3. At the receiving end, each path is equipped with an independent decoder. After each packet is transmitted, each path is first decoded independently, and the successfully decoded data packet is immediately passed to the receiving end's master decoder. Each packet that reaches the master decoder must be uploaded after the previous packet is uploaded to the application layer. After the data packets of the same generation are uploaded, a backup is retained in the master decoder to assist in subsequent encoding. If a packet is eventually lost, the receiving end will send feedback, which includes the packet loss rate e of this generation, the average end-to-end delay D of this generation, and the change in the number of Inter-coded packets. The feedback information is in D F Arrives at the sending end after the time slot;

[0010] Step 4: At the current time t≥D F In the case of , when the sender does not send Inter code packets in the previous generation and receives feedback information from the previous generation, it determines whether it is necessary to send Inter code packets according to the feedback information; if it is not necessary to send, jump to step 2; if it is necessary to send, calculate the coding interval L of the Inter code packet u , and jump to step 5;

[0011] Step 5: The sender receives the data according to L u Generate Inter code packets and send them every L u Each packet is inserted into an Inter-coded packet until the end of this generation, and the resulting sequence is scheduled to multiple paths for transmission;

[0012] Step 6: At the current time t≥D FIn this case, the receiving end first decodes independently on each path. Successfully decoded data packets are immediately aggregated to the master decoder, and known packets are submitted to the application layer in real time and in sequence. Each packet arriving at the master decoder must be uploaded only after the previous packet is uploaded to the application layer. After uploading, data packets of the same generation are retained in the master decoder as a backup to assist in subsequent encoding. After aggregation to the master decoder, if all packets have not been Inter-decoded and no packets are lost, feedback information is sent to recommend reducing Inter-encoded packets. If there is still packet loss, jump to step 7.

[0013] Step 7. If there are still undecoded packets after Intra decoding, the main decoder will prioritize decoding the earliest lost packet upon receiving the Inter coded packet, and immediately upload the decoded packet to the application layer. If all lost packets are recovered during Inter decoding, feedback is sent, suggesting that the number of Inter coded packets remain unchanged. If there are still unrecovered packets after Inter decoding within the specified range, all existing and unsubmitted packets are submitted in order, and feedback is sent, suggesting that more Inter coded packets be added.

[0014] Step 8: When the transmitter sends Inter code packets in the previous generation and receives feedback on the change of the number of Inter code packets, the number of Inter code packets is adjusted according to the feedback instruction; when the number of Inter code packets is reduced, the new L is calculated. u , if at this time L u ≥L th , this generation does not send Inter code packets and jumps to step 2; then this generation does not send Inter code packets and jumps to step 2; when the number of code packets is increased or the number remains unchanged, calculate the new L u , and jump to step 5;

[0015] Step 9. Repeat steps 5-8 until the data transmission is completed.

[0016] Furthermore, in step 1, adaptive adjustment of Inter code packets is achieved by adjusting system parameters to optimize transmission quality and efficiency. Specifically, the change rate of Inter code packets increases with the increase of weight factor γ; the use range of Inter code packets increases with the minimum packet loss rate threshold e th The increase and maximum interval threshold L th The expected end-to-end delay decreases first and then increases as the number of Inter-coded packets increases, while the expected packet loss rate increases as the number of Inter-coded packets increases.

[0017] Furthermore, the Inter code packet is responsible for cross-path encoding and decoding, and the Intra code packet on each path is only responsible for encoding and decoding on the path.

[0018] Furthermore, if an inter-coded packet needs to be sent in a generation, then the inter-coded packet is a linear combination of all previous source packets of the current generation. Let α i is a coding coefficient randomly selected from a finite field, p i is the source information packet, then the Inter encoding packet is:

[0019]

[0020] Furthermore, the data packet b transmitted on path p i,p It may be a source information packet or an Inter coding packet. Let β i,p is a coding coefficient randomly selected from a finite field, then the kth Intra coding packet on the path is:

[0021]

[0022] Furthermore, if no Inter packets were sent in the previous generation, the number of Inter packets that need to be sent in the current generation depends on the total packet loss rate e during decoding in the previous generation. The coding interval of the packets that need to be sent in the current generation is:

[0023]

[0024] Furthermore, if the previous generation sent an Inter code packet and the current generation sender receives feedback to add an Inter code packet, the coding interval of the Inter code packet of the current generation is:

[0025]

[0026] Furthermore, if the previous generation sent Inter packets, and the current generation transmitter receives feedback to reduce Inter packets, and determines that Inter packets should still be sent in the current generation, the interval of Inter packets in the current generation is:

[0027] L u =γL u .

[0028] The present invention provides an application layer network coding design method for multipath transmission networks, which has the following advantages:

[0029] 1. This invention fully utilizes delayed feedback information, measured at generational intervals, to estimate the multipath packet loss rate and decoding status, and uses this information to determine the amount of additional redundancy added by the transmitter. This significantly improves transmission efficiency and packet arrival rate while ensuring data freshness at the receiver. Specifically, when adding Inter-coded packets for the first time, the number of added packets depends on the total packet loss rate (e) of the previous generation's decoding. Each subsequent transmission increases or decreases the number of Inter-coded packets based on the previous generation's feedback.

[0030] 2. This invention increases effective redundancy without changing existing multipath transmission parameters, minimizing changes to legacy systems and reducing replacement costs. Specifically, the invention maintains the existing intra-coded packet transmission system, but instead adds additional inter-coded packet redundancy to reduce bit error rates and end-to-end latency.

[0031] 3. This invention requires minimal feedback information and fewer network parameters. The next-generation transmission parameters are derived through simple feedback, resulting in robustness in complex multipath transmission channels. Specifically, the invention adjusts the number of Inter coded packets using only a single variation factor, γ, which requires fewer parameters than other models. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic diagram illustrating a detailed transmission process of a transmitting end and a receiving end according to an embodiment of an application layer network coding design method for a multipath transmission network of the present invention;

[0033] Figure 2 This is a schematic diagram illustrating an example of the transmission and encoding process at the transmitting end of an embodiment of an application layer network coding design method for a multipath transmission network according to the present invention;

[0034] Figure 3 This is a schematic diagram of a transmitter coding and transmission scheme flow diagram of an embodiment of an application layer network coding design method for a multipath transmission network according to the present invention;

[0035] Figure 4 This is a flowchart of a receiving-end decoding and feedback solution according to an embodiment of an application layer network coding design method for a multipath transmission network of the present invention;

[0036] Figure 5 This is a schematic diagram of end-to-end delay simulation performance of an embodiment of an application layer network coding design method for a multipath transmission network according to the present invention. DETAILED DESCRIPTION

[0037] In order to better understand the purpose, structure and function of the present invention, the following further describes in detail an application layer network coding design method for multipath transmission networks of the present invention in conjunction with the accompanying drawings.

[0038] The present invention is applicable to multipath transmission networks with sparse feedback information. At the beginning of each generation, all information packets of the current generation are prepared and scheduled and sent by the transmitter. The receiver first decodes each path independently, then decodes jointly, and instructs the transmitter to change redundancy in the feedback based on the decoding results. The transmitter determines the change in additional redundancy based on the delayed feedback of each generation. The transmitter achieves a trade-off between system reliability and freshness by adjusting the redundancy change speed factor and threshold.

[0039] In one embodiment, reference Figure 2 and Figure 3 As shown in the flowchart, the present invention proposes an application layer network coding design method for multipath transmission networks, including the following main steps:

[0040] Step 1: Before transmission begins, set system parameters based on previous transmission quality and transmission requirements, including: Inter coding packet coding maximum interval threshold L th , L th ≥2, Inter code packet change weight factor γ, γ>1, by adjusting the maximum interval threshold L of the code packet th , minimum packet loss rate threshold e th The adaptive adjustment of Inter code packets is realized by changing the weight factor γ to optimize the transmission quality and efficiency. Among them, the change rate of Inter code packets increases with the increase of the weight factor γ; the use range of Inter code packets increases with the minimum packet loss rate threshold e th The increase and maximum interval threshold L th The expected end-to-end delay decreases first and then increases as the number of Inter-coded packets increases, while the expected packet loss rate increases as the number of Inter-coded packets increases.

[0041] Step 2: At the start of transmission, the sender initializes the number of Inter packets to be sent to zero. At the beginning of each generation, all packets to be transmitted in that generation are obtained and scheduled for transmission across multiple paths. Each path has its own encoder and decoder, independently generating Intra packets. Each Intra packet is a linear combination of all packets and Inter packets following the previous Intra packet in that path. The sender continues to send Inter packets even after completing its scheduled transmission task, until receiving feedback from the receiver, to ensure that all packets in each generation can be successfully decoded.

[0042] Step 3. At the receiving end, each path is equipped with an independent decoder. After each packet is transmitted, each path is first decoded independently, and the successfully decoded data packet is immediately passed to the main decoder at the receiving end. Each information packet that arrives at the main decoder must be uploaded after the previous information packet is uploaded to the application layer. After uploading, the data packets of the same generation are retained in the main decoder as a backup to assist in subsequent encoding. If a packet is eventually lost, the receiving end will send feedback. The feedback content includes the packet loss rate e of this generation, the average end-to-end delay D of this generation, and the recommendation on the change in the number of Inter-coded packets. The feedback information is in D F It arrives at the sender after the time slot.

[0043] Step 4: At the current time t≥D F In the case of , when the sender does not send Inter code packets in the previous generation and receives feedback information from the previous generation, it determines whether it is necessary to send Inter code packets based on the feedback information. If it is not necessary to send, jump to step 2; if it is necessary to send, calculate the coding interval L of the Inter code packet u , and jump to step 5. Let the data packet transmitted on path p be b i,p , b i,p It may be a source information packet or an Inter code packet, then the kth Intra code packet on the path is where β i,p are coding coefficients randomly selected from a finite field.

[0044] Specifically, if a generation needs to send an Inter coded packet, then the Inter coded packet is a linear combination of all previous packets of the current generation, which is where α i is a coding coefficient randomly selected from a finite field, p i It is the source packet.

[0045] If no Inter code packets were sent in the previous generation, the number of Inter code packets that need to be sent in the current generation depends on the total packet loss rate of the previous generation and the coding interval of the code packets that need to be sent in the current generation.

[0046] Step 5: The sender receives the data according to L u Generate Inter code packets and send them every L u The information packets are inserted into an Inter coding packet until the end of this generation, and the resulting sequence is scheduled to be transmitted on multiple paths.

[0047] Step 6: At the current time t≥D FIn this case, the receiver first decodes each path independently. Successfully decoded packets are immediately aggregated to the master decoder, which then submits known packets to the application layer in real time and in sequence. Each packet arriving at the master decoder must wait until the previous packet has been uploaded to the application layer before it can be uploaded. Packets of the same generation are backed up in the master decoder after being uploaded to facilitate subsequent encoding. After aggregation to the master decoder, if all packets have not been Inter-decoded and no packets have been lost, feedback is sent, suggesting a reduction in Inter-encoded packets. If packet loss persists, the process proceeds to step 7.

[0048] Step 7: If there are still undecoded packets after Intra decoding, the master decoder, upon receiving Inter packets, prioritizes decoding the oldest lost packet and immediately uploads the decoded packet to the application layer. If all lost packets are recovered during Inter decoding, feedback is sent, suggesting that the number of Inter packets remain unchanged. If there are still unrecovered packets after Inter decoding within the specified range, all existing and undelivered packets are submitted in order, and feedback is sent, suggesting that an additional Inter packet be added.

[0049] Step 8: When the transmitter sends Inter code packets in the previous generation and receives feedback on the number of Inter code packets, the number of Inter code packets is adjusted according to the feedback instruction. If the transmitter receives feedback on the increase of Inter code packets, the coding interval is If the sender receives feedback to reduce the Inter coding packet, the coding interval L u =γL u .

[0050] When reducing the number of Inter coding packets, calculate the new L u , if the new L u ≥L th , this generation does not send Inter code packets and jumps to step 2; when the number of code packets is increased or the number remains unchanged, calculate the new L u , and skip to step 5.

[0051] Step 9. Repeat steps 5-8 until the data transmission is completed.

[0052] Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings.

[0053] Figure 1 It is a schematic diagram of the detailed transmission process of the sending end and the receiving end mentioned in the first embodiment of the present invention.

[0054] in

[0055] There are 4 source packets to be sent in one generation. The initial Inter coding interval L is u =4, maximum Inter coding threshold L th = 6, with a change factor of γ = 2. Path 1 requires one time slot to transmit a data packet, and path 2 requires two time slots to transmit a data packet. The feedback delay is one time slot. All packets are pre-scheduled to each path by the sender before each generation. End-to-end delay is defined as the difference between the time a packet is received in order and the time the first packet in that generation is sent.

[0056] At the beginning of the first time slot, the sender sends packet p1 on path 1 and p2 on path 2. p1 is sent successfully, but p2 fails to send.

[0057] At the beginning of the second time slot, the transmitter sends p3 on path 1, and path 2 is not idle and no packet is sent. The receiver receives p1, saves a copy of p1 in the decoder, and directly transmits p1 to the upper layer.

[0058] At the beginning of the third time slot, the transmitter sends packet p4 along path 1 and Inter-coded packet u1 along path 2. Both p4 and u1 fail to be sent. The receiver receives packet p3. Because packet p2, which precedes p3, has not yet been successfully decoded, p3 remains in the decoder and is not passed to the upper layer.

[0059] At the beginning of the 4th time slot, the transmitter sends the Intra coded packet c of path 1 on path 1. 1,1 ,Path 2 is not idle and no packet is sent.,The receiving end does not receive the packet.

[0060] At the beginning of the 5th time slot, the transmitter sends p5 on path 1 and path 2 Intra coded packet c on path 2. 2,1 p5 and c 2,1 All are sent successfully. The receiving end receives c 1,1 , and according to c 1,1 Decode p4 on the same path. Since p2 before p4 has not been successfully decoded, p3 and p4 remain in the decoder and are not transmitted to the upper layer.

[0061] At the beginning of the sixth time slot, the transmitter sends packet p6 on path 1. Path 2 is not idle and no packets are sent. Therefore, packet p6 fails to be sent. The receiver receives packet p5. Because packet p2, which precedes packet p5, has not yet been successfully decoded, packets p3, p4, and p5 remain in the decoder and are not passed to the upper layer.

[0062] At the beginning of the 7th time slot, the transmitter sends p7 on path 1 and p8 on path 2. Both p7 and p8 are sent successfully. The receiver receives c 2,1 , and according to c2,1 Recover the Inter coded packet u1 lost in path 2. In the decoder, u1 decodes p2. p2, p3, p4, and p5 are sent to the upper layer.

[0063] At the beginning of the 8th time slot, the transmitter sends the Intra coded packet c on path 1. 1,2 , path 2 is not idle and no packet is sent. c 1,2 The receiver receives p7. Since p6, which precedes p7, has not been decoded successfully, p7 remains in the decoder and is not sent to the upper layer.

[0064] At the beginning of the 9th time slot, the transmitter sends Inter coded packet u2 on path 1, and path 2 starts sending repeated Inter coded packets. u2 is sent successfully, but repeated Intra coded packets fail to be sent. The receiver receives p8 and c 1,2 , and according to c 1,2 Decode p6 on path 1. p6, p7, and p8 are sent to the upper layer. The receiving end determines that a generation has been fully transmitted.

[0065] At the beginning of the 10th time slot, the transmitter continues to send repeated Inter packets, all of which are successful, as no feedback is received from the receiver. The receiver receives u2 and determines that the current generation has been transmitted and that there are excess Inter packets left. The receiver sends feedback to inform the transmitter that the current generation has been transmitted and instructs it to reduce the number of Inter packets.

[0066] At the beginning of the 11th time slot, the transmitter receives feedback and recalculates the new L u =γL u (old)=8, because the new L u ≥L th =6, so the sender does not send Inter coded packets in this generation, and re-adds Intra coded packets to the information packets of this generation and schedules them to be transmitted over different paths.

[0067] In the 1st to 9th time slots, the detailed transmission process between the transmitter and the receiver is as follows: Figure 1 In the above time slots 1-9, a complete generation transmission is completed, with an average end-to-end delay of 6.125 and a transmission reliability of 100%.

[0068] Figure 2This is a schematic diagram of the example transmission and encoding process of the transmitting end mentioned in the first embodiment of the present invention. Before a generation is sent, all information packets of that generation will be prepared. Here, it is assumed that the number of encoding packets in a generation is 4. Before starting multipath transmission, the transmitting end will first add Inter encoding packets. Assume that the sending interval of Inter encoding packets is L. u =4, meaning an Inter coded packet is added after every four packets. After this step, the number of packets requiring multipath transmission (including source packets and Inter coded packets) increases to five. The sender schedules the coded packets once according to the minimum transmission delay principle, which requires minimizing the maximum transmission delay and independently adds Intra coded packets to each path based on their respective erasure probabilities. In this example, there are two paths: the first path Lc1=3, and the second path Lc2=2. Lc1=3 means that for every three packets allocated on path 1, an Intra coded packet is added, and the same applies to path 2. After scheduling, all coded packets will be transmitted in order by the sender.

[0069] Figure 5 The following is a schematic diagram of the end-to-end delay performance simulation within one generation of this example. One generation contains 1000 packets to be sent. As can be seen from the figure, the larger L u The insertion of Inter-coded packets is reduced, resulting in a rapid increase in end-to-end delay; with the L u As it continues to increase, its influence decreases. u If it is too small, too many Inter-coded packets will delay packet transmission and increase end-to-end delay. c It also affects the end-to-end delay. Usually, a larger L c Will reduce latency, especially in L u When large. Although the larger L c This is sometimes advantageous, but due to the weaker error correction capabilities of intra-coded packets, it results in additional delay, so a balanced coding strategy is required. Poor channel conditions can increase end-to-end delay.

[0070] This paper presents an application-layer network coding design method for multipath transmission networks. By combining intra and inter coding, it introduces adaptive strategies and feedback mechanisms to improve transmission efficiency and reliability while meeting data freshness requirements. This method not only fully leverages the potential of multipath transmission networks, but also maintains compatibility with existing systems, providing a cost-effective and practical solution for optimizing the performance of multipath transmission systems.

[0071] It will be understood that the present invention is described by way of some embodiments, and it will be appreciated by those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are intended to be protected by the present invention.

Claims

1. A method for designing application layer network coding for multipath transmission networks, characterized in that: The specific steps include: Step 1: Before transmission begins, set system parameters based on previous transmission quality and transmission requirements, including: Inter coding packet coding maximum interval threshold L th , L th ≥2, Inter code packet change weight factor γ, γ>1, by adjusting the maximum interval threshold L of the code packet th And the variable weight factor γ realizes the adaptive adjustment of Inter coding packets to optimize transmission quality and efficiency; Step 2: At the start of transmission, the sender initializes the number of Inter packets to be sent to zero. At the beginning of each generation, it obtains all the information packets to be transmitted in that generation and schedules and transmits them on multiple paths. Each path has its own encoder and decoder, independently generating Intra packets. Each Intra packet is a linear combination of all information packets and Inter packets after the previous Intra packet in that path. Before receiving feedback from the receiver, the sender will continue to send Inter packets after completing the established transmission task to ensure that all information packets in each generation can be successfully decoded. Step 3. At the receiving end, each path is equipped with a decoder. After each packet is transmitted, each path first decodes it independently. The successfully decoded data packets are immediately passed to the receiving end's master decoder. Each packet that arrives at the master decoder must be uploaded after the previous packet is uploaded to the application layer. After the data packets of the same generation are uploaded, a backup is retained in the master decoder to assist in subsequent encoding. If a packet is eventually lost, the receiving end will send feedback, which includes the packet loss rate n of this generation, the average end-to-end delay D of this generation, and the recommendation on the change in the number of Inter-coded packets. The feedback information is in D F Arrives at the sending end after the time slot; Step 4: At the current time t≥D F In the case of , when the sender does not send Inter code packets in the previous generation and receives feedback information from the previous generation, it determines whether it is necessary to send Inter code packets according to the feedback information; if it is not necessary to send, jump to step 2; if it is necessary to send, calculate the coding interval L of the Inter code packet u , and jump to step 5; Step 5: The sender receives the data according to L u Generate Inter code packets and send them every L u Each packet is inserted into an Inter-coded packet until the end of this generation, and the resulting sequence is scheduled to multiple paths for transmission; Step 6: At the current time t≥D F In this case, the receiving end first decodes independently on each path. The successfully decoded data packets are immediately aggregated to the master decoder, and the known information packets are submitted to the application layer in real time and in sequence. Each information packet arriving at the master decoder must be uploaded after the previous information packet is uploaded to the application layer. After uploading, the data packets of the same generation are retained in the master decoder as a backup to assist in subsequent encoding. After being aggregated to the master decoder, if all information packets have not been Inter-decoded and no information packets are lost, feedback information is sent to recommend reducing Inter-encoded packets. If there is still packet loss, jump to step 7. Step 7. If there are still undecoded packets after Intra decoding, the main decoder will prioritize decoding the earliest lost packet upon receiving the Inter coded packet, and immediately upload the decoded packet to the application layer. If all lost packets are recovered during Inter decoding, feedback is sent, suggesting that the number of Inter coded packets remain unchanged. If there are still unrecovered packets after Inter decoding within the specified range, all existing and unsubmitted packets are submitted in order, and feedback is sent, suggesting that more Inter coded packets be added. Step 8: When the transmitter sends Inter code packets in the previous generation and receives feedback on the change of the number of Inter code packets, the number of Inter code packets is adjusted according to the feedback instruction; when the number of Inter code packets is reduced, the new L is calculated. u , if at this time L u ≥L th , then the current generation does not send Inter code packets and jumps to step 2; when the number of code packets is increased or the number remains unchanged, calculate the new L u , and jump to step 5; Step 9: Repeat steps 5-8 until data transmission is completed; In step 1, adaptive adjustment of Inter code packets is achieved by adjusting system parameters to optimize transmission quality and efficiency. Specifically, the following steps are included: the change rate of Inter code packets increases with the increase of weight factor γ; the use range of Inter code packets increases with the minimum packet loss rate threshold e th The increase and maximum interval threshold L th The expected end-to-end delay decreases first and then increases as the number of Inter-coded packets increases, while the expected packet loss rate increases as the number of Inter-coded packets increases. Inter code packets are responsible for cross-path encoding and decoding, while Intra code packets on each path are only responsible for encoding and decoding on the path itself. In step 4, if a generation needs to send an Inter code packet, then the Inter code packet is a linear combination of all previous information packets of the current generation, which is where α i is a coding coefficient randomly selected from a finite field, p i It is the source packet.

2. The method for designing application layer network coding for multipath transmission networks according to claim 1, characterized in that: In step 4, if the previous generation did not send Inter code packets, the number of Inter code packets that need to be sent in this generation depends on the total packet loss rate of the previous generation and the coding interval of the Inter code packets that need to be sent in this generation. Where e is the packet loss rate when the receiving end fails to decode.

3. The method for designing application layer network coding for multipath transmission networks according to claim 1, wherein: In step 2, the data packet b transmitted on path p i,p Is a source information packet or an Inter coded packet, and the kth Intra coded packet on the path is where β i,p are coding coefficients randomly selected from a finite field.

4. The method for designing application layer network coding for multipath transmission networks according to claim 1, wherein: In step 8, if the sender receives feedback for adding Inter coding packets, the Inter coding interval is reduced to the original times, that is If the transmitter receives feedback to reduce the Inter coding packet, the Inter coding interval increases to γ ​​times the original one, that is, L u =γL u .

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