Wireless network error control method and system
By constructing a cross-checking relationship between adjacent data packets through a wireless network error control method based on Reed-Solomon codes, the problems of redundant resource waste and insufficient error correction capability for sudden errors in wireless networks are solved, and efficient error correction capability and resource utilization are improved.
Patent Information
- Application Number
- CN202511461548.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-14
- Publication Date
- 2026-01-23
AI Technical Summary
Wireless networks suffer from high bit error rates and burst errors during data transmission. Existing error control mechanisms lead to wasted redundant resources and insufficient ability to correct burst errors.
A wireless network error control method based on Reed-Solomon codes is adopted. By performing RS encoding and redundancy compression at the transmitting end, a cross-check relationship between adjacent data packets is constructed. Error checking and retransmission are performed at the receiving end, and the check order is optimized to improve error correction capability.
It effectively reduces network resource waste, improves the ability to handle sudden errors, achieves a balance between reliability and efficiency, reduces coding redundancy, and enhances error correction capabilities.
Smart Images
Figure CN121397642A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of wireless data transmission technology, specifically to a wireless network error control method and system. Background Technology
[0002] Wireless networks offer advantages in data transmission efficiency and convenience, but they also suffer from two inherent drawbacks: high bit error rate and burst errors, which severely restrict transmission reliability. Burst errors are typically caused by channel interference, multipath fading, or node congestion, leading to the loss of a large number of consecutive data packets. Furthermore, dynamically changing channel conditions cause the bit error rate to be extremely low under favorable conditions but rise sharply under adverse conditions.
[0003] Current mainstream error control mechanisms fall into three categories, all of which suffer from fundamental flaws: First, Automatic Repeat Request (ARQ) relies on receiver feedback and sender retransmission. While it can detect errors, repeated retransmissions at high bit error rates significantly increase latency and channel load, and it cannot proactively correct errors. Second, Forward Error Correction (FEC) achieves proactive error correction by pre-adding redundant bits, but the redundancy length is fixed: at low bit error rates, redundant bits consume effective bandwidth, reducing throughput; at high bit error rates, it may still fail due to error exceeding the limit. Third, a hybrid ARQ & FEC approach attempts to combine the advantages of both, but the redundancy problem in the FEC part remains unresolved, and joint embedding of data packets during retransmission actually increases packet length. In summary, existing mechanisms have two major common flaws: First, wasted redundancy resources: static redundancy design is mismatched with dynamic channel conditions, resulting in low utilization of redundant bits at low bit error rates, leading to wasted bandwidth and energy; second, insufficient burst error correction capability: isolated packet verification mechanisms struggle to handle consecutive errors, and when the number of error bits exceeds the single packet error correction threshold, the retransmission probability increases.
[0004] Therefore, there is an urgent need for an error control method that reduces redundancy to save resources at low bit error rates, improves error correction capabilities at high bit error rates (especially for burst errors), and breaks through the single-packet error correction limit through inter-packet verification relationships. This requires innovative coding structures to achieve joint error correction capabilities across data packets while reducing the redundancy cardinality. Summary of the Invention
[0005] The purpose of this invention is to solve the problems of redundant resource waste and insufficient error correction capability in the above-mentioned background technology. It proposes a wireless network error control method and system, which adopts a check bit reassembly and cross-packet collaborative error correction mechanism. By constructing cross-check relationships between adjacent data packets, the number of redundant bits is reduced while improving the error correction capability of a single packet.
[0006] To achieve the objectives of this invention, the technical solution provided by this invention is as follows:
[0007] First aspect
[0008] This application provides a wireless network error control method, which is a wireless network error control method based on Reed-Solomon codes, and includes the following steps:
[0009] Step 1: RS encoding the data packet at the sending end;
[0010] Step 2: Perform redundant compression on the RS encoded packets;
[0011] Step 3: Perform error checking on the data packets at the receiving end;
[0012] Step 4: Successfully received or retransmitted data packet.
[0013] Second aspect
[0014] This application also provides a wireless network error control system, the system including a transmitter and a receiver, the system executing a wireless network error control method based on Reed-Solomon codes, the method including the following steps:
[0015] Step 1: RS encoding the data packet at the sending end;
[0016] Step 2: Perform redundant compression on the RS encoded packets;
[0017] Step 3: Perform error checking on the data packets at the receiving end;
[0018] Step 4: Successfully received or retransmitted data packet.
[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0020] (1) The innovative RS redundancy compression coding algorithm effectively reduces network resource waste. This mechanism divides the parity bit generated by RS code into three parts and performs an XOR operation on the parity bits in adjacent messages, so that only two-thirds of the parity bits of each message need to be sent. While ensuring error correction capability, it reduces coding redundancy by one-third, significantly improving network resource utilization and solving the resource waste problem caused by the mismatch between redundant bits and bit error rate in traditional error control mechanisms.
[0021] (2) The cross-checking relationship of adjacent data packets significantly enhances the ability to handle burst errors. During the redundancy compression process, this invention constructs a check association between adjacent data packets through an XOR operation, enabling each data packet's check bits not only to be used for its own check but also to provide check assistance to adjacent data packets. When a burst error occurs in the channel, the error correction capability can be dynamically extended from t bits to 3t bits by utilizing the check information of preceding and following adjacent data packets, effectively addressing the challenges of high bit error rates and burst errors in wireless networks, and overcoming the limitations of traditional mechanisms in terms of insufficient error correction capability under bursty channels.
[0022] (3) A balance between reliability and efficiency is achieved by adopting cross-packet verification and retransmission strategies. In the error checking phase, this invention prioritizes self-verification. If a failure occurs, forward cross-verification and backward cross-verification are triggered sequentially. Unnecessary computational overhead is reduced through buffer management and verification order optimization. In the retransmission phase, the maximum number of retransmissions is limited to 3, and the length of the parity bit is dynamically adjusted in combination with the channel status. This ensures the reliability of data transmission and avoids the resource waste caused by blind retransmissions in the traditional ARQ mechanism. It can achieve efficient error control under different channel conditions. Attached Figure Description
[0023] Figure 1 This is a flowchart illustrating the wireless network error control method provided in an embodiment of the present invention.
[0024] Figure 2 This is a schematic diagram of the RS encoding process for data packets in an embodiment of the present invention;
[0025] Figure 3 This is a schematic diagram of the redundant compression process for RS encoded packets in an embodiment of the present invention;
[0026] Figure 4 This is a schematic diagram of the error checking process for data packets in an embodiment of the present invention;
[0027] Figure 5 This is a schematic diagram illustrating the process of successful reception or retransmission of data packets in an embodiment of the present invention. Detailed Implementation
[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0029] like Figure 1 As shown, this embodiment provides a wireless network error control method based on Reed-Solomon codes, including the following steps:
[0030] Step S1: RS encoding of data packets at the sending end: The core is to use the mathematical characteristics of RS code to generate basic check bits. By appending 3 check bits (check segments 1, 2, and 3) to the message segment, basic error correction capability is given to the data packet, which is a prerequisite for subsequent recoding.
[0031] like Figure 2 As shown, the specific implementation method of step S1 is as follows:
[0032] Step S11: Constructing the parameterized RS code: Based on the Galois field (GF) theory, in the finite field GF(2 m Constructing a systematic RS code on ) : Define code length n=2 m -1, for example, when m=8, n=255, corresponding to GF(256), set the message segment length k and error correction capacity t, satisfying the parity bit length nk=3t (e.g., when k=223, t=16, n=271); use generator polynomial Where α is the primitive element, b is the offset constant, and i is the index variable (integer) of the multiplication term.
[0033] Step S12: Segmented check bit mapping: Divide message segment M into {x1, x2…x} k The generated 3t-bit check bits are divided into three independent segments according to their function to construct structured redundancy: namely Provides basic error correction capabilities; Used for association with preceding packages; Used for subsequent packet coupling.
[0034] Step S13: Systematic Encoding Packet Construction: Implement the following process through the encoder: Input message segment M = {x1, x2, ..., x k}; Calculate the verification polynomial c(x) = x n-k • M(x) mod g(x); Output system code: The total length is k+3t.
[0035] Step S2: Redundancy compression of RS encoded packets: The parity relationship is reconstructed by XOR operation of adjacent data packet parity bits to reduce redundant bits (compressed from 3t bits to 2t bits), and a cross-checking mechanism is constructed to enhance the ability to handle sudden errors.
[0036] like Figure 3 As shown, the specific implementation method of step S2 is as follows:
[0037] Step S21: Data packet infrastructure preservation: preserve the message segment M and the first check segment of the current data packet. Keep it unchanged and copy it to the beginning of the data packet to be sent, as follows:
[0038]
[0039] Step S22: Implement forward dependency using XOR operation: Perform an XOR operation on the second check segment of the current data packet and the third check segment of the previous data packet, and append the result to the first check segment as the second check segment of the data packet to be sent, as shown in the following formula:
[0040]
[0041] Step S23: Achieve backcoupling through XOR operation: Modify the third check segment of the current data packet. Perform an XOR operation with the second check segment of the next data packet, and use the result as the second check segment of the next data packet, and so on.
[0042] Step S24: Optimize and send the transmission structure: Send the redundantly compressed RS data packet RS_Packet'.
[0043] Step S3: Perform error checking on data packets at the receiving end: This step utilizes a mechanism combining self-checking and cross-checking, leveraging the correlation of check bits in adjacent data packets to enhance error correction capabilities while reducing resource waste caused by redundant checks. This stage is based on the cross-checking relationship generated by RS recoding, using a cross-checking strategy to improve error correction efficiency in scenarios with sudden errors.
[0044] like Figure 4 As shown, the specific implementation method of step S3 is as follows:
[0045] Step S31: Single Packet Autonomous Error Correction: Each data packet contains a complete t-bit checksum segment, which means that each data packet has... It uses error correction capabilities to correct errors; after receiving a data packet, it extracts its checksum. use Perform independent error correction on the current data packet; if the number of error bits is less than... If the error is successfully corrected and a message segment is output, the error length is greater than 1. Then step S32 is triggered.
[0046] Step 32: Precursor Packet Co-verification: Extract the precursor packet 'RS_Packet' from the receive buffer. i-1 Complete check segment The current package With RS_Packet' i-1 of Perform an XOR operation to restore the original parity segment of 'RS_Packet'. joint and Error correction is performed. If the number of error bits is less than t, the error is successfully corrected and a message segment is output. If the number of error bits is greater than t, step S33 is triggered.
[0047] Step S33: Successor Packet Co-verification: Waiting to receive the successor packet 'RS_Packet' i+1 It completes its single-packet self-correction (step S31). If the subsequent packet verification is successful, it recalculates its original error based on the message segment of the subsequent packet. Calculated With the received follow-up packet XOR, restore the current packet checksum. The formula is as follows:
[0048]
[0049] joint (Total parity bits 3t bits) Correct errors in the current packet; if the correction is successful, output a message segment; otherwise, trigger the retransmission mechanism (see step S4).
[0050] Step S34: Multi-packet consecutive error handling: If the subsequent packet RS_Packet' i+1 If the basic verification fails, continue waiting for the second successor packet 'RS_Packet'. i+2 The verification result, if RS_Packet' i+2 If the verification is successful, then use RS_Packet' i+2 Activate RS_Packet i+1 of Execute the logic in step 3.3, and then verify the successful packet RS_Packet. i+1 Activate the current package If the packet is RS_Packet' i+2 If it still fails, the current data packet will be retransmitted directly.
[0051] Step S4: Successful Reception or Packet Retransmission: If the packet is successfully checked, then the packet is received. If the packet cannot be successfully checked, it will be retransmitted even if there are two adjacent packets. The sender will retransmit the packet until it can be successfully checked or the maximum number of retransmissions is reached. To prevent excessive waste of network resources in poor channel conditions, the maximum number of retransmissions is set to 3. After three failed retransmissions, the transmission channel condition is considered very poor.
[0052] like Figure 5 As shown, the specific implementation method of step S4 is as follows:
[0053] Step S41: Determine the retransmission trigger condition: We set three scenarios that require retransmission of data packet i, where Case1 is RS_Packet' i Failed but RS_Packet' i+1 If successful, immediately retransmit 'RS_Packet' i Case 2 is RS_Packet' i Failed and RS_Packet' i+1 Failed, but RS_Packet' i+2 If successful, then immediately retransmit 'RS_Packet' iCase 3 is 'RS_Packet' i 'RS_Packet' i+1 'RS_Packet' i+2 If three packets fail consecutively, they will be retransmitted immediately. Furthermore, if three packets fail consecutively, the first packet will be retransmitted first, as subsequent packets cannot provide assistance. If the 2T error correction capability of the data packet has been restored and there is no support from subsequent packets, then it will be retransmitted directly.
[0054] Step S42: Retransmission packet processing: First, a retransmission request is sent. The receiving end sends a retransmission request containing the packet sequence number to the sending end. Then, the verification information is reused. When the sending end retransmits, it only retransmits the message segment and the two verification segments to avoid retransmitting the entire packet.
[0055] Step S43: Collaborative recovery after retransmission: For Case 1, if RS_Packet' i If the retransmission is successful, clear the data packet 'RS_Packet'. i+1 The previous cache; for Case 2, the third check segment of packet i+1 is activated by retransmitting packet i. If the check succeeds, it is used to activate the third check segment of packet i+2. If it still fails, packet RS_Packet is retransmitted. i+1 For Case 3, try activating 'RS_Packet'. i+1 of If successful, continue activating 'RS_Packet'. i+2 of If any packet fails, subsequent packets are retransmitted in sequence.
[0056] Step S44: Retransmission Termination Control: Set the maximum number of retransmissions. The maximum number of retransmissions for a single packet is 3. The counter starts to increment from the first retransmission. If the packet still fails after 3 retransmissions, it is discarded.
[0057] Finally, it should be noted that the above embodiments are merely illustrative and explanatory of the present invention, and are not intended to limit the present invention to the scope of the described embodiments. Furthermore, those skilled in the art will understand that the present invention is not limited to the above embodiments, and many more variations and modifications can be made based on the teachings of the present invention, all of which fall within the scope of protection claimed by the present invention.
Claims
1. A wireless network error control method, characterized in that, The method is a wireless network error control method based on Reed-Solomon codes, which includes the following steps: Step S1: RS encoding the data packet at the sending end; Step S2: Perform redundant compression on the RS encoded packet; Step S3: Perform error checking on the data packets at the receiving end; Step S4: Successfully received or retransmitted data packet.
2. The wireless network error control method according to claim 1, characterized in that, Step S1 includes the following steps: Step S11: Constructing parameterized RS codes; based on Galois field GF theory, in the finite field GF(2 m Constructing a systematic RS code on ) : Define code length n=2 m -1; Set the message segment length k and error correction capacity t, satisfying the parity bit length nk = 3t; Use a generator polynomial Where α is the primitive element, b is the offset constant, and i is the index variable (integer) of the multiplication term; Step S12: Segmented check bit mapping; Divide message segment M into {x1, x2…x} k The generated 3t-bit check bits are divided into three independent segments according to their function to construct structured redundancy: namely Provides basic error correction capabilities; Used for association with preceding packets; Used for subsequent packet coupling; Step S13: Systematically construct the encoded package; implement the following process through the encoder: Input message segment M = {x1, x2, ..., x k }; Calculate the verification polynomial c(x) = x n-k • M(x) mod g(x); Output system code: The total length is k+3t.
3. The wireless network error control method according to claim 1, characterized in that, Step S2 includes the following steps: Step S21: Check the message segment M and the first check segment of the current data packet. Keep it unchanged and copy it to the beginning of the data packet to be sent, as follows: Step S22: Perform an XOR operation on the second check segment of the current data packet and the third check segment of the previous data packet, and append the result to the first check segment to form the second check segment of the data packet to be sent, as shown in the following formula: Step S23: Add the third check segment of the current data packet Perform an XOR operation with the second check segment of the next data packet, and use the result as the second check segment of the next data packet, and so on; Step S24: Send the redundantly compressed RS data packet RS_Packet'.
4. The wireless network error control method according to claim 1, characterized in that, Step S3 includes the following steps: Step S31: Single packet autonomous error correction; each data packet contains a complete t-bit checksum segment, and each data packet has... It uses error correction capabilities to correct errors; after receiving a data packet, it extracts its checksum. use Perform independent error correction on the current data packet; if the number of error bits is less than... If the error is successfully corrected and a message segment is output, the error length is greater than 1. Then step S32 is triggered; Step S32: Precursor packet co-verification; extract the precursor packet 'RS_Packet' from the receive buffer. i-1 Complete check segment The current package With RS_Packet' i-1 of Perform an XOR operation to restore the original parity segment of 'RS_Packet'. joint and Error correction is performed. If the number of error bits is less than t, the error is successfully corrected and a message segment is output. If the number of error bits is greater than t, step S33 is triggered. Step S33: Successor packet co-verification; wait to receive the successor packet 'RS_Peacket' i+1 It completes its single-packet self-correction, and if the subsequent packet verification is successful, it recalculates its original error based on the message segment of the subsequent packet. Calculated With the received follow-up packet XOR, restore the current packet checksum. The formula is as follows: joint Correct the current packet; if the correction is successful, output the message segment; otherwise, trigger the retransmission mechanism. Step S34: Handling consecutive errors in multiple packets; if the subsequent packet is RS_Packet' i+1 If the basic verification fails, continue waiting for the second successor packet 'RS_Packet'. i+2 The verification result, if RS_Peacket' i+2 If the verification is successful, then use RS_Peacket' i+2 Activate RS_Packet i+1 of Execute the logic of step S33, and then verify the successful packet RS_Packet. i+1 Activate the current package If the packet is RS_Packet' i+2 If it still fails, the current data packet will be retransmitted directly.
5. The wireless network error control method according to claim 1, characterized in that, Step S4 includes the following steps: Step S41: Determine the retransmission trigger condition; Set three scenarios that require retransmission of data packet i, Case 1 is RS_Packet' i Failed but RS_Packet' i+1 If successful, immediately retransmit 'RS_Packet' i Case 2 is RS_Packet' i Failed and RS_Packet' i+1 Failed, but RS_Packet' i+2 If successful, then immediately retransmit 'RS_Packet' i Case 3 is 'RS_Packet' i 'RS_Packet' i+1 'RS_Packet' i+2 If there are consecutive failures, retransmit immediately; in addition, if three consecutive packets fail, the first packet is retransmitted first, because subsequent packets cannot provide assistance. If the 2T error correction capability of the data packet has been restored and there is no support from subsequent packets, then retransmit directly. Step S42: Retransmission packet processing; First, a retransmission request is sent. The receiving end sends a retransmission request containing the packet sequence number to the sending end. Then, the verification information is reused. When the sending end retransmits, it only retransmits the message segment and the two verification segments to avoid retransmitting the entire packet. Step S43: Collaborative recovery after retransmission; For Case 1, if RS_Packet' i If the retransmission is successful, clear the data packet 'RS_Packet'. i+1 The previous cache; for Case 2, the third check segment of packet i+1 is activated by retransmitting packet i. If the check is successful, it is used to activate the third check segment of packet i+2. If it still fails, packet RS_Packet is retransmitted. i+1 For Case 3, try activating 'RS_Packet'. i+1 of If successful, continue activating 'RS_Packet'. i+2 of If any packet fails, subsequent packets are retransmitted in order. Step S44: Retransmission termination control; Set the maximum number of retransmissions limit. The maximum number of retransmissions for a single packet is 3. The counter starts to accumulate from the first retransmission. If the packet still fails after 3 retransmissions, it is discarded.
6. A wireless network error control system, characterized in that, The system includes a transmitter and a receiver, and the system executes a wireless network error control method based on Reed-Solomon codes, the method including the following steps: Step S1: RS encoding the data packet at the sending end; Step S2: Perform redundant compression on the RS encoded packet; Step S3: Perform error checking on the data packets at the receiving end; Step S4: Successfully received or retransmitted data packet.
7. A wireless network error control system according to claim 6, characterized in that, Step S1 includes the following steps: Step S11: Constructing parameterized RS codes; based on Galois field GF theory, in the finite field GF(2 m Constructing a systematic RS code on ) : Define code length n=2 m -1; Set the message segment length k and error correction capacity t, satisfying the parity bit length nk = 3t; Use a generator polynomial Where α is the primitive element, b is the offset constant, and i is the index variable (integer) of the multiplication term; Step S12: Segmented check bit mapping; Divide message segment M into {x1, x2…x} k The generated 3t-bit check bits are divided into three independent segments according to their function to construct structured redundancy: namely Provides basic error correction capabilities; Used for association with preceding packets; Used for subsequent packet coupling; Step S13: Systematically construct the encoded package; implement the following process through the encoder: Input message segment M = {x1, x2, ..., x k }; Calculate the verification polynomial c(x) = x n-k • M(x) mod g(x); Output system code: The total length is k+3t.
8. A wireless network error control system according to claim 6, characterized in that, Step S2 includes the following steps: Step S21: Check the message segment M and the first check segment of the current data packet. Keep it unchanged and copy it to the beginning of the data packet to be sent, as follows: Step S22: Perform an XOR operation on the second check segment of the current data packet and the third check segment of the previous data packet, and append the result to the first check segment to form the second check segment of the data packet to be sent, as shown in the following formula: Step S23: Add the third check segment of the current data packet Perform an XOR operation with the second check segment of the next data packet, and use the result as the second check segment of the next data packet, and so on; Step S24: Send the redundantly compressed RS data packet RS_Packet'.
9. A wireless network error control system according to claim 6, characterized in that, Step S3 includes the following steps: Step S31: Single packet autonomous error correction; each data packet contains a complete t-bit checksum segment, and each data packet has... It uses error correction capabilities to correct errors; after receiving a data packet, it extracts its checksum. use Perform independent error correction on the current data packet; if the number of error bits is less than... If the error is successfully corrected and a message segment is output, the error length is greater than 1. Then step S32 is triggered; Step S32: Precursor packet co-verification; extract the precursor packet 'RS_Packet' from the receive buffer. i-1 Complete check segment The current package With RS_Packet' i-1 of Perform an XOR operation to restore the original parity segment of 'RS_Packet'. joint and Error correction is performed. If the number of error bits is less than t, the error is successfully corrected and a message segment is output. If the number of error bits is greater than t, step S33 is triggered. Step S33: Successor packet co-verification; wait to receive the successor packet 'RS_Packet' i+1 It completes its single-packet self-correction, and if the subsequent packet verification is successful, it recalculates its original error based on the message segment of the subsequent packet. Calculated With the received follow-up packet XOR, restore the current packet checksum. The formula is as follows: joint Correct the current packet; if the correction is successful, output the message segment; otherwise, trigger the retransmission mechanism. Step S34: Handling consecutive errors in multiple packets; if the subsequent packet is RS_Packet' i+1 If the basic verification fails, continue waiting for the second successor packet 'RS_Packet'. i+2 The verification result, if RS_Packet' i+2 If the verification is successful, then use RS_Packet' i+2 Activate RS_Packet i+1 of Execute the logic of step S33, and then verify the successful packet RS_Packet. i+1 Activate the current package If the packet is RS_Packet' i+2 If it still fails, the current data packet will be retransmitted directly.
10. A wireless network error control system according to claim 6, characterized in that, Step S4 includes the following steps: Step S41: Determine the retransmission trigger condition; Set up three scenarios that require retransmission of data packet i, Case 1 is RS_RS' i Failed but RS_Packet' i+1 If successful, immediately retransmit RS_RS' i Case 2 is RS_Packet' i Failed and RS_Packet' i+1 Failed, but RS_Packet' i+2 If successful, then immediately retransmit 'RS_Packet' i Case 3 is 'RS_Packet' i 'RS_Packet' i+1 'RS_Packet' i+2 If there are consecutive failures, retransmit immediately; in addition, if three consecutive packets fail, the first packet is retransmitted first, because subsequent packets cannot provide assistance. If the 2T error correction capability of the data packet has been restored and there is no support from subsequent packets, then retransmit directly. Step S42: Retransmission packet processing; First, a retransmission request is sent. The receiving end sends a retransmission request containing the packet sequence number to the sending end. Then, the verification information is reused. When the sending end retransmits, it only retransmits the message segment and the two verification segments to avoid retransmitting the entire packet. Step S43: Collaborative recovery after retransmission; For Case 1, if RS_Packet' i If the retransmission is successful, clear the data packet 'RS_Packet'. i+1 The previous cache; for Case 2, the third check segment of packet i+1 is activated by retransmitting packet i. If the check is successful, it is used to activate the third check segment of packet i+2. If it still fails, packet RS_Packet is retransmitted. i+1 For Case 3, try activating 'RS_Packet'. i+1 of If successful, continue activating 'RS_Packet'. i+2 of If any packet fails, subsequent packets are retransmitted in order. Step S44: Retransmission termination control; Set the maximum number of retransmissions limit. The maximum number of retransmissions for a single packet is 3. The counter starts to accumulate from the first retransmission. If the packet still fails after 3 retransmissions, it is discarded.