A reliable telegraph transmission method and system for a dual-redundant network for ships

Abstract

This invention relates to the field of telegraph transmission technology, and more particularly to a reliable telegraph transmission method and system for marine dual-redundant networks. The method includes the following steps: the sending end queues and persists messages according to priority; the body and attachments are concatenated, an attachment index is recorded, and the data is segmented into data segments at a specific granularity; a transmission link and backoff are selected from a policy table according to link quality level and priority; the receiving end verifies and updates the received bitmap, and attaches a snapshot of the bitmap to the acknowledgment / denial message; the sending end parses the bitmap to locate missing segments, and if the number of missing segments exceeds a threshold, the entire message is retransmitted; otherwise, selective retransmission is performed, with the threshold being an efficiency coefficient multiplied by the total number of segments; backoff is determined according to priority and quality level, generally withholding all messages when the link degrades or is interrupted. This invention achieves the technical effect of minimizing the bandwidth consumption of task communication by reliable transmission without introducing new protocol layers, protocol message types, or network devices.

Description

Technical Field

[0001] This invention relates to the field of telegraph transmission technology, and in particular to a reliable telegraph transmission method and system for marine dual-redundant networks. Background Technology

[0002] Messages are divided into text messages and data messages. A single message can be up to 2MB and can carry up to 50 attachments. Marine communication uses dual-redundant physical links, but the overall bandwidth is limited, and mission-related communications must be prioritized. To achieve reliable message transmission under these constraints, there are currently four main technical approaches, each with its own shortcomings.

[0003] Represented by the US SyncPath project, redundancy is pre-coded before transmission, and the receiver recovers from packet loss automatically using its error correction capabilities, without needing to send back acknowledgments. The drawback is that the redundancy overhead is constant—regardless of whether the link experiences packet loss, it always occupies a preset proportion of bandwidth. Hybrid ARQ combines RS erasure coding with hop-by-hop selective retransmission, requiring redundant packets to be sent even when the link is normal. RSMA-BRQ focuses on the multiple access layer, not end-to-end reliable transmission. The common shortcomings of the above schemes are: redundancy is injected before packet loss, wasting bandwidth when the link is normal; and the redundancy degree is fixed, making it impossible to accurately match the actual packet loss volume.

[0004] Represented by the SDN trust-aware dual-channel switching architecture proposed by Bhatt and Kurup, nodes are equipped with a primary link and a backup link, automatically switching when the trust score falls below a threshold. However, this architecture has several drawbacks: the backup link is idle and wastes bandwidth when it is functioning normally; it only distinguishes between normal and fault states, lacking differentiated handling for intermediate link degradation; and it lacks packet priority differentiation.

[0005] Represented by the Contested-Mesh Radio "governed message envelope" protocol, this approach is geared towards mesh multi-hop relay networks and relies on multiple nodes along the route for store-and-forward communication. Its core drawback is its cumbersome mechanism; marine telegraphs primarily rely on point-to-point transmission and lack the conditions for multi-hop relay topologies.

[0006] Common shortcomings of existing solutions include: (1) Redundancy and packet loss are disconnected; (2) When the backup link is normal, it is idle or constantly dual-transmission wastes bandwidth; (3) There is no message-level priority differentiation guarantee; (4) Conventional ARQ packet loss is retransmission of the whole message, which is extremely inefficient in large message scenarios; (5) Disconnection recovery depends on multi-hop relay, which does not conform to the point-to-point model of ships; (6) Protocol modification is costly.

[0007] Therefore, a new inter-ship communication method is urgently needed to solve the above-mentioned technical problems. Summary of the Invention

[0008] This invention aims to at least solve one of the technical problems existing in related technologies. To this end, this invention provides a reliable telegraph transmission method and system for marine dual-redundant networks, which achieves the technical effect of minimizing the bandwidth consumption of task communication by reliable transmission simply by adding software modules at the sending end and the receiving end, without introducing new protocol layers, protocol message types or network devices.

[0009] This invention provides a reliable telegraph transmission method for marine dual-redundant networks, comprising the following steps: S1: The sending end sorts the messages into the urgent queue, the fast queue, or the general queue according to the message priority and writes them to the local persistent storage medium simultaneously. S2: The sending end concatenates the main text and attachments in sequence, records the attachment index, and then divides it into data segments according to the segmentation granularity. Each data segment is appended with a message identifier, segment number, total number of segments, data payload, and cyclic redundancy check code. S3: The sending end selects the sending link and backoff strategy from the preset strategy table according to the link quality level and message priority of link A and link B; S4: The receiving end performs cyclic redundancy check on the data segment and updates the received bitmap, then appends the snapshot of the received bitmap to the message body of the acknowledgment / denial message and sends it back to the sending end. S5: The sending end parses the received bitmap to locate missing segments. When the number of missing segments is greater than the missing segment threshold, the entire segment is retransmitted; otherwise, selective retransmission is performed. The missing segment threshold is equal to the efficiency coefficient multiplied by the total number of segments. S6: The sender decides whether to back off based on the message priority and link quality level. Messages with normal priority will be fully backed off when the link quality level is reduced or interrupted.

[0010] According to a reliable telegraph transmission method for marine dual-redundant networks provided by the present invention, the sending end arranges messages into the urgent queue, the urgent queue, or the general queue according to the message priority; under bandwidth constraints, the sending end schedules according to quota allocation rules: all available bandwidth quota within a preset time window is allocated to the urgent queue until it is empty; after the urgent queue is empty, the remaining quota is allocated to the urgent queue; after the urgent queue is also empty, the remaining quota is allocated to the general queue; when a new message is inserted into the urgent queue in the middle of the time window, if a data segment of a general message is currently being transmitted, the next transmission time slot immediately switches to the data segment of the urgent message after the corresponding data segment is transmitted.

[0011] According to a reliable telegraph transmission method for marine dual-redundant networks provided by the present invention, the sending end selects the segmentation granularity based on the message type and current link quality: the default segmentation granularity for text messages is 128 bytes, and the default segmentation granularity for data messages is 512 bytes; when the smoothed packet loss rate exceeds a preset segmentation narrowing threshold, the segmentation granularity is narrowed by one level, with text messages narrowed from 128 bytes to 64 bytes and data messages from 512 bytes to 256 bytes; when the smoothed packet loss rate falls below the segmentation narrowing threshold and remains stable for a preset period of time, the default segmentation granularity is restored; when the data message volume exceeds a preset large message threshold, the sending end splits the data segment sequence into two consecutive subsets according to the segment number range, and transmits them in parallel via link A and link B respectively.

[0012] According to the present invention, a reliable telegraph transmission method for marine dual-redundant networks is provided, wherein the link quality level is determined by the following four-dimensional indicators: both packet loss rate and round-trip delay are smoothed using an exponentially weighted moving average with a smoothing coefficient of 0.9; the conditions for a good level are that the smoothed packet loss rate is less than or equal to a preset first packet loss threshold, the smoothed round-trip delay is less than or equal to 1.5 times the baseline round-trip delay, the connectivity status is connected, and the load level is less than or equal to 0.8 times the link's rated capacity; the conditions for a degraded level are that the smoothed packet loss rate is greater than the first packet loss threshold and less than or equal to a preset second packet loss threshold, or the smoothed round-trip delay is greater than 1.5 times the baseline round-trip delay and the connectivity status is connected; the conditions for an interrupted level are that the smoothed packet loss rate is greater than the second packet loss threshold, or the round-trip delay times out, or the connectivity status is disconnected.

[0013] According to the present invention, a reliable telegraph transmission method for marine dual-redundant networks includes a preset strategy table comprising: when the quality levels of both Link A and Link B are good, urgent and emergency messages are sent via Link A, and general messages are sent via Link B without backoff; when the quality level of Link A is declining and Link B is good or declining, urgent messages are sent in parallel on both Link A and Link B without backoff, and emergency messages are switched to Link B for transmission when the load level of Link B is below the handover acceptance threshold; otherwise, they are still sent via Link A with an extended acknowledgment message, etc. When the timeout period expires, the first transmission of new urgent messages is temporarily suspended, and general messages are completely backed up. When link A is interrupted and link B is available, all messages are retransmitted through link B, and probe frames are continuously transmitted on link A. When both link A and link B are interrupted, all unacknowledged messages are stored in the local persistent storage medium, and probe frames are alternately transmitted on link A and link B. The probe frame contains a probe flag, a transmission timestamp, and a cyclic redundancy check code. When a link receives an acknowledgment message corresponding to a preset number of consecutively successful probe frames, it is determined that the corresponding link has been restored.

[0014] According to the present invention, a reliable telegraph transmission method for marine dual-redundant networks is provided, wherein the missing segment number threshold is equal to the efficiency coefficient multiplied by the total number of segments, and the efficiency coefficient is a preset constant greater than 0 and less than 1, representing the ratio of the equivalent overhead of segment-by-segment retransmission to the overhead of full-message retransmission; when the missing segment number is greater than the missing segment number threshold, the sending end performs the full-message retransmission, and the receiving end clears the existing receiving bitmap and re-verifies segment by segment after receiving the full-message retransmission; when the missing segment number is less than or equal to the missing segment number threshold, the missing segment content read by the sending end from the local persistent storage medium is repackaged and sent to the sending queue, and segments that are not zero in the receiving bitmap are not retransmitted.

[0015] According to a reliable telegraph transmission method for marine dual-redundant networks provided by the present invention, the sending end performs differentiated backoff based on the message priority and the link quality level: Urgent messages do not perform backoff waiting under any link quality level; urgent messages do not backoff when the link quality level is good, and the backoff waiting time during a decline is equal to the base backoff time multiplied by 2 raised to the power of the current retransmission count, multiplied by an urgent message backoff growth factor, where the urgent message backoff growth factor is greater than 1; general messages, when the link quality level is declining, have a backoff waiting time equal to the base backoff time multiplied by 2 raised to the power of the current retransmission count, and perform complete backoff, entering persistent waiting when the link quality level is interrupted; urgent messages have no limit on the number of retransmissions, and when an urgent message reaches a preset maximum number of urgent message retransmissions, retransmission stops and the message alarm is retained; when a general message reaches a preset maximum number of general message retransmissions, retransmission stops and the message is discarded.

[0016] According to the present invention, a reliable telegraph transmission method for marine dual-redundant networks is provided. The sending end establishes a persistent record in the local persistent storage medium using a composite key message identifier and a receiving end identifier. The persistent record includes complete message data, segmentation information, a retransmission status bitmap, a timestamp group, and message priority. The segmentation information records the segmentation granularity, the total number of segments, and a list of cyclic redundancy check values ​​for each data segment. The retransmission status bitmap records the acknowledgment status and the number of retransmissions for each data segment. When the sending end restarts, it scans the local persistent storage directory, parses each persistent record, reconstructs the retransmission task in descending order of message priority and ascending order of message creation time, and resumes transmission according to the preset strategy table based on the link quality levels of the current link A and link B. When the used storage space exceeds a preset high watermark, messages with a general priority that exceed the preset maximum transmission time are first discarded, followed by messages with an urgent priority that exceed the timeout limit. Messages with an extremely urgent priority are not automatically discarded due to timeout.

[0017] According to the reliable telegraph transmission method for marine dual-redundant networks provided by the present invention, when the same message is sent to multiple receiving ends, the sending end establishes a group acknowledgment table, which includes a list of group members and a member-by-member acknowledgment status. The member-by-member acknowledgment status includes three states: received, partially received, and unacknowledged. The sending end also maintains a missing segment bitmap, the number of retransmissions, the most recent acknowledgment time, and the remaining backoff waiting time. The sending end does not send retransmission segments to receiving ends that have received the message; it only retransmits the missing segments to receiving ends that have received the message partially; and it retransmits all data segments to receiving ends that have not acknowledged the message. The sending end first broadcasts the main text and attachment index, and then retransmits the missing attachment segments according to the differences in the received bitmaps reported by each receiving end. The number of retransmissions for each receiving end is counted independently.

[0018] The present invention also provides a reliable telegraph transmission system for marine dual-redundant networks, comprising: Enqueue persistence module: The sending end queues messages into the urgent queue, the priority queue, or the general queue according to the message priority and writes them synchronously to the local persistent storage medium; Message segmentation module: The sending end concatenates the main text and attachments in sequence, records the attachment index, and then segments the data into data segments according to the segmentation granularity. Each data segment is appended with a message identifier number, segment number, total number of segments, data payload, and cyclic redundancy check code. Link scheduling module: The sending end selects the sending link and backoff strategy from the preset strategy table according to the link quality level and message priority of link A and link B; Bitmap feedback module: The receiving end performs cyclic redundancy check on the data segment and updates the received bitmap, and appends the received bitmap snapshot to the message body of the acknowledgment / denial message and sends it back to the sending end; Selective retransmission module: The sending end parses the received bitmap to locate missing segments. When the number of missing segments is greater than the missing segment threshold, the entire segment is retransmitted; otherwise, selective retransmission is performed. The missing segment threshold is equal to the efficiency coefficient multiplied by the total number of segments. Backoff decision module: The sender decides whether to backoff based on the message priority and link quality level. Messages with normal priority will be fully backed off when the link quality level is reduced or interrupted.

[0019] The above-described one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects: This invention employs a technique where the sending end uniformly segments the text and attachments into data segments and adds a cyclic redundancy check (CRC) code to each segment. The receiving end independently performs CRC checks on each data segment and maintains a receive bitmap covering all segment sequence numbers. A snapshot of the receive bitmap is appended to the message body of an existing acknowledgment / denial message and sent back to the sending end. The sending end parses the receive bitmap to locate missing segments, selectively retransmits only the missing segments, and degrades to full packet retransmission when the number of missing segments exceeds a threshold. This achieves the technical effects of not sending any redundant data when the link is normal, having near-zero additional bandwidth overhead, retransmission volume being only proportional to packet loss, and significantly improving retransmission efficiency for 2MB large data packets when packet loss occurs at the end.

[0020] This invention employs a technique that determines the default segmentation granularity based on message type, and narrows the segmentation granularity by one level when the link quality deteriorates and the smoothed packet loss rate exceeds a preset segmentation narrowing threshold. After the packet loss rate falls back and remains stable for a preset period of time, the default segmentation granularity is restored. This technique achieves the technical effect of improving the retransmission success rate on degraded links by increasing the probability of short data segments being received completely and correctly compared to long data segments, and by reducing the bandwidth cost of a single retransmission after a short segment is damaged compared to a long segment.

[0021] This invention employs a technique of alternately sending lightweight probe frames containing only probe markers, transmission timestamps, and cyclic redundancy check codes on Link A and Link B during link interruption. The link is determined to be restored only when it receives confirmation messages corresponding to probe frames that have been successfully transmitted a preset number of times. After restoration, the data is retransmitted in batches according to the priority order of urgent, urgent, and general. This technique achieves the technical effects of avoiding the loss of a large number of retransmitted data segments due to misjudgment of "jitter recovery", reducing the load of invalid retransmissions on degraded links, and ensuring the priority recovery of critical messages.

[0022] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a flowchart illustrating a reliable telegraph transmission method for marine dual-redundant networks provided by the present invention.

[0025] Figure 2 This is a schematic diagram of the structure of a reliable telegraph transmission system for a shipboard dual-redundant network provided by the present invention.

[0026] Figure label: 100. Enqueue Persistence Module; 200. Message Segmentation Module; 300. Link Scheduling Module; 400. Bitmap Feedback Module; 500. Selective Retransmission Module; 600. Backoff Decision Module. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. The following embodiments are used to illustrate this invention but cannot be used to limit the scope of this invention.

[0028] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0029] The following is combined Figures 1 to 2 This invention is described.

[0030] Example like Figure 1 As shown, Figure 1 A flowchart illustrating a reliable telegraph transmission method for marine dual-redundancy networks provided by this invention includes the following steps: S1: The sending end sorts the messages into the urgent queue, the fast queue, or the general queue according to the message priority and writes them to the local persistent storage medium simultaneously. S2: The sending end concatenates the main text and attachments in sequence, records the attachment index, and then divides it into data segments according to the segmentation granularity. Each data segment is appended with a message identifier, segment number, total number of segments, data payload, and cyclic redundancy check code. S3: The sending end selects the sending link and backoff strategy from the preset strategy table according to the link quality level and message priority of link A and link B; S4: The receiving end performs cyclic redundancy check on the data segment and updates the received bitmap, then appends the snapshot of the received bitmap to the message body of the acknowledgment / denial message and sends it back to the sending end. S5: The sending end parses the received bitmap to locate missing segments. When the number of missing segments is greater than the missing segment threshold, the entire segment is retransmitted; otherwise, selective retransmission is performed. The missing segment threshold is equal to the efficiency coefficient multiplied by the total number of segments. S6: The sender decides whether to back off based on the message priority and link quality level. Messages with normal priority will be fully backed off when the link quality level is reduced or interrupted.

[0031] Specifically, the sending end arranges messages into the urgent queue, the urgent queue, or the general queue according to the message priority; under bandwidth constraints, the sending end schedules according to the quota allocation rules: all available bandwidth quota within a preset time window is allocated to the urgent queue until it is empty; after the urgent queue is empty, the remaining quota is allocated to the urgent queue; after the urgent queue is also empty, the remaining quota is allocated to the general queue; when a new message is inserted into the urgent queue in the middle of the time window, if a data segment of a general message is currently being sent, the next transmission time slot immediately switches to the data segment of the urgent message after the corresponding data segment is completed.

[0032] Specifically, the sending end selects the segmentation granularity based on the message type and current link quality: the default segmentation granularity for text packets is 128 bytes, and the default segmentation granularity for data packets is 512 bytes; when the smoothed packet loss rate exceeds a preset segmentation narrowing threshold, the segmentation granularity is narrowed by one level, with text packets narrowed from 128 bytes to 64 bytes and data packets from 512 bytes to 256 bytes; when the smoothed packet loss rate falls below the segmentation narrowing threshold and remains stable for a preset period of time, the default segmentation granularity is restored; when the data packet size exceeds a preset large message threshold, the sending end splits the data segment sequence into two consecutive subsets according to the segment number range, and sends them in parallel via link A and link B respectively.

[0033] Specifically, the link quality level is determined by the following four-dimensional indicators: packet loss rate and round-trip time are both smoothed using an exponentially weighted moving average, and the smoothing coefficient is... The value is set to 0.9. Specifically, the link quality assessment uses the following exponentially weighted moving average formula: in, The smoothed packet loss rate after the nth sampling is given. The smoothed packet loss rate after the (n-1)th sampling is... This represents the instantaneous packet loss rate actually counted within the nth sampling period. The smooth round-trip time after the nth sampling is... The smooth round-trip time after the (n-1)th sampling is... The instantaneous round-trip delay actually counted within the nth sampling period, according to the embodiments of the present invention. , where n is the ordinal number of the sampling number.

[0034] The conditions for a good level are: a smoothed packet loss rate less than or equal to a preset first packet loss threshold, a smoothed round-trip time less than or equal to 1.5 times the baseline round-trip time, an on / off status of being connected, and a load level less than or equal to 0.8 times the link's rated capacity; the conditions for a degraded level are: a smoothed packet loss rate greater than the first packet loss threshold and less than or equal to a preset second packet loss threshold, or a smoothed round-trip time greater than 1.5 times the baseline round-trip time and an on / off status of being connected; the conditions for an interrupted level are: a smoothed packet loss rate greater than the second packet loss threshold, or a round-trip timeout, or an on / off status of being disconnected.

[0035] Specifically, the preset strategy table includes: when the quality levels of both Link A and Link B are good, urgent and emergency messages are sent via Link A, and general messages are sent via Link B without backoff; when the quality level of Link A is declining and Link B is good or declining, urgent messages are sent in parallel on both Link A and Link B without backoff, and emergency messages are switched to Link B for transmission when the load level of Link B is lower than the handover acceptance threshold; otherwise, they are still sent via Link A with an extended confirmation message timeout and a temporary suspension of the first release of new emergency messages. Normally, all messages are completely backed off. When link A is interrupted and link B is available, all messages are redirected to link B, and probe frames are continuously sent on link A. When both link A and link B are interrupted, all unacknowledged messages are stored in the local persistent storage medium, and probe frames are alternately sent on link A and link B. The probe frame contains a probe flag, a sending timestamp, and a cyclic redundancy check code. When a link receives an acknowledgment message corresponding to a preset number of consecutively successful probe frames, it is determined that the corresponding link has been restored.

[0036] Specifically, the missing segment threshold is equal to the efficiency coefficient multiplied by the total number of segments. The efficiency coefficient is a preset constant greater than 0 and less than 1, typically ranging from 0.6 to 0.7, representing the ratio of the equivalent overhead of segment-by-segment retransmission to the overhead of full-message retransmission. When the number of missing segments is greater than the missing segment threshold, the sending end performs full-message retransmission, and the receiving end clears the existing received bitmap and re-verifies segment by segment after receiving the full-message retransmission. When the number of missing segments is less than or equal to the missing segment threshold, the missing segment content read by the sending end from the local persistent storage medium is repackaged and sent to the sending queue, and segments that are not zero in the received bitmap are not retransmitted.

[0037] Specifically, the sending end performs differentiated backoff based on the message priority and the link quality level: Urgent messages do not perform backoff waiting under any link quality level; urgent messages do not backoff when the link quality level is good, and the backoff waiting time during a decline is equal to the base backoff time multiplied by 2 raised to the power of the current retransmission count, multiplied by the urgent message backoff growth factor, where the urgent message backoff growth factor is greater than 1; general messages, when the link quality level is declining, have a backoff waiting time equal to the base backoff time multiplied by 2 raised to the power of the current retransmission count, and perform complete backoff; when the link quality level is interrupted, they enter persistent waiting; urgent messages have no limit on the number of retransmissions; urgent messages stop retransmission and retain message alarms when they reach the preset maximum number of urgent message retransmissions; general messages stop retransmission and discard messages when they reach the preset maximum number of general message retransmissions.

[0038] Specifically, the sending end establishes a persistent record in the local persistent storage medium using the composite key message identifier number plus the receiving end identifier number. The persistent record includes complete message data, segmentation information, retransmission status bitmap, timestamp group, and message priority. The segmentation information records the segmentation granularity, total number of segments, and a list of cyclic redundancy check values ​​for each data segment. The retransmission status bitmap records the acknowledgment status and retransmission count of each data segment. When the sending end restarts, it scans the local persistent storage directory, parses each persistent record, reconstructs the retransmission task in descending order of message priority and ascending order of message creation time, and resumes transmission according to the preset strategy table based on the link quality levels of the current link A and link B. When the used storage space exceeds the preset high watermark, messages with a general priority that have exceeded the preset maximum transmission time limit are first discarded, followed by messages with an urgent priority that have exceeded the time limit. Messages with an extremely urgent priority are not automatically discarded due to timeout.

[0039] Specifically, when the same message is sent to multiple receivers, the sending end establishes a group acknowledgment table, which includes a list of group members and the acknowledgment status of each member. The acknowledgment status of each member includes three states: received, partially received, and unacknowledged. The sending end also maintains a missing segment bitmap, the number of retransmissions, the most recent acknowledgment time, and the remaining backoff waiting time. The sending end does not send retransmission segments to receivers that have received the message, only retransmits the missing segments to receivers that have received the message partially, and retransmits all data segments to receivers that have not acknowledged the message. The sending end first sends the main text and attachment index via broadcast, and then retransmits the missing attachment segments of each receiver based on the differences in the received bitmaps reported by each receiver. The number of retransmissions for each receiver is counted independently.

[0040] To verify the technical effectiveness of this invention, simulation experiments were conducted using the Python programming language. The simulation results are presented below in four aspects: retransmission bandwidth efficiency, packet loss at the end of large packets, segmentation granularity narrowing, and jitter recovery misjudgment.

[0041] (a) Comparison of retransmission data volume between selective retransmission and whole-cell retransmission The simulation conditions are as follows: the message size is 2MB (2097152 bytes), the segmentation granularity is 512 bytes, there are a total of 4096 segments, and the packet loss rates are 0.5%, 1%, 2%, 5%, and 10%, respectively. For each packet loss rate, missing segments are randomly determined. Retransmission of the entire message requires retransmission of all 2097152 bytes. This scheme only retransmits the missing segments.

[0042] Table 1. Comparison of retransmission data volume between selective retransmission and whole-cell retransmission

[0043] As shown in Table 1, the amount of retransmitted data in this scheme is directly proportional to the number of missing segments, rather than the total message length. At a 0.5% packet loss rate, the amount of retransmitted data in this scheme is only about 0.59% of the total packet retransmission amount; even at a high packet loss rate of 10%, it still saves 89.50% of bandwidth. When the link is normal (packet loss rate is 0%), this scheme does not generate any redundant overhead, while constant redundancy schemes always occupy a fixed proportion of additional bandwidth.

[0044] (ii) Scenarios of packet loss at the end of a large message The simulation conditions are: 2MB datagram, 512-byte segments, totaling 4096 segments, with only the last segment lost. Retransmitting the entire datagram would require retransmitting all 2097152 bytes, while this solution only retransmits the missing last 51-byte segment. The retransmission data volume is only 0.0244% of that of the entire message retransmission, a difference of 4096 times. This verifies the significant improvement in retransmission efficiency of this solution in scenarios where packets are lost at the end of large messages.

[0045] (III) Effect of segmented granularity reduction The simulation conditions are: a degraded link byte error rate of 0.02%. The single-segment corruption probability of a 512-byte segment is approximately 9.734%, while that of a 256-byte segment is approximately 4.992%. After narrowing... The probability of a single segment being damaged was reduced to approximately 51.28% of its original value; simultaneously, the retransmission cost after a single segment being damaged was reduced from 512 bytes to 256 bytes. The combined effect significantly improved the retransmission success rate on degraded links.

[0046] (iv) Probability of false positives during jitter recovery The simulation conditions were: the probability of receiving an acknowledgment for a single probe frame during link jitter was 0.3, simulating 100,000 jitter probes. The false positive probability of using the "determine recovery upon receiving one acknowledgment" approach was approximately 30.05%; the false positive probability of using the proposed scheme, which requires "receiving acknowledgments for three consecutive probe frames," was approximately 2.635%, a reduction of about an order of magnitude. This verifies the effectiveness of the continuous acknowledgment mechanism in avoiding false positives during jitter recovery and reducing invalid retransmissions.

[0047] like Figure 2 As shown, the following describes a reliable telegraph transmission system for marine dual-redundant networks provided by the present invention. The reliable telegraph transmission system for marine dual-redundant networks described below can be referred to in correspondence with the reliable telegraph transmission method for marine dual-redundant networks described above. It includes the following modules: Enqueue Persistence Module 100: The sending end queues messages into the urgent queue, the priority queue, or the general queue according to the message priority and writes them synchronously to the local persistent storage medium; Message segmentation module 200: The sending end concatenates the main text and attachments in sequence, records the attachment index, and then divides it into data segments according to the segmentation granularity. Each data segment is appended with a message identifier number, segment number, total number of segments, data payload, and cyclic redundancy check code. Link scheduling module 300: The sending end selects the sending link and backoff strategy from the preset strategy table according to the link quality level and message priority of link A and link B; Bitmap Feedback Module 400: The receiving end performs cyclic redundancy check on the data segment and updates the received bitmap, and appends the snapshot of the received bitmap to the message body of the acknowledgment / denial message and sends it back to the sending end; Selective retransmission module 500: The sending end parses the received bitmap to locate missing segments. When the number of missing segments is greater than the missing segment threshold, the entire segment is retransmitted; otherwise, selective retransmission is performed. The missing segment threshold is equal to the efficiency coefficient multiplied by the total number of segments. Backoff decision module 600: The sender decides whether to backoff based on the message priority and link quality level. Messages with normal priority will be fully backed off when the link quality level is reduced or interrupted.

[0048] The embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0049] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0051] It should be noted that the embodiments of this disclosure can be implemented using hardware, software, or a combination of both. The hardware portion can be implemented using dedicated logic; the software portion can be stored in memory and executed by a suitable instruction execution system, such as a microprocessor or dedicated-design hardware. Those skilled in the art will understand that the above-described devices and methods can be implemented using computer-executable instructions and / or included in processor control code, for example, such code provided on a programmable memory or a data carrier such as an optical or electronic signal carrier.

[0052] While this disclosure has been described with reference to several specific embodiments, it should be understood that this disclosure is not limited to the specific embodiments disclosed. This disclosure is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A reliable telegraph transmission method for marine dual-redundant networks, characterized in that, Includes the following steps: S1: The sending end sorts the messages into the urgent queue, the fast queue, or the general queue according to the message priority and writes them to the local persistent storage medium simultaneously. S2: The sending end concatenates the main text and attachments in sequence, records the attachment index, and then divides it into data segments according to the segmentation granularity. Each data segment is appended with a message identifier, segment number, total number of segments, data payload, and cyclic redundancy check code. S3: The sending end selects the sending link and backoff strategy from the preset strategy table according to the link quality level and message priority of link A and link B; S4: The receiving end performs cyclic redundancy check on the data segment and updates the received bitmap, then appends the snapshot of the received bitmap to the message body of the acknowledgment / denial message and sends it back to the sending end. S5: The sending end parses the received bitmap to locate missing segments. When the number of missing segments is greater than the missing segment threshold, the entire segment is retransmitted; otherwise, selective retransmission is performed. The missing segment threshold is equal to the efficiency coefficient multiplied by the total number of segments. S6 The sender determines whether to back off based on message priority and link quality level. Messages with normal priority will be fully backed off when the link quality level is reduced or interrupted.

2. The reliable telegraph transmission method for marine dual-redundant networks according to claim 1, characterized in that, The sending end arranges messages into the urgent queue, the fast queue, or the general queue according to the message priority. Under bandwidth constraints, the sending end schedules according to the quota allocation rules: all available bandwidth quota within a preset time window is allocated to the urgent queue until it is empty; after the urgent queue is empty, the remaining quota is allocated to the fast queue; after the fast queue is also empty, the remaining quota is allocated to the general queue; when a new message is inserted into the urgent queue in the middle of the time window, if a data segment of a general message is currently being sent, the next transmission time slot immediately switches to the data segment of the urgent message after the corresponding data segment is completed.

3. A reliable telegraph transmission method for marine dual-redundant networks according to claim 2, characterized in that, The sending end selects the segmentation granularity according to the message type and the current link quality: the default segmentation granularity for text packets is 128 bytes, and the default segmentation granularity for data packets is 512 bytes. When the smoothed packet loss rate exceeds the preset segmentation narrowing threshold, the segmentation granularity is narrowed by one level, with the text packet narrowed from 128 bytes to 64 bytes and the data packet from 512 bytes to 256 bytes. When the smoothed packet loss rate falls below the segmentation narrowing threshold and remains stable for a preset period of time, the default segmentation granularity is restored. When the data packet size exceeds the preset large packet threshold, the sending end splits the data segment sequence into two consecutive subsets according to the segment number range, and sends them in parallel via Link A and Link B, respectively.

4. A reliable telegraph transmission method for marine dual-redundant networks according to claim 3, characterized in that, The link quality level is determined by the following four-dimensional indicators: both packet loss rate and round-trip time are smoothed using an exponentially weighted moving average with a smoothing coefficient of 0.9; the conditions for a good level are that the smoothed packet loss rate is less than or equal to a preset first packet loss threshold, the smoothed round-trip time is less than or equal to 1.5 times the baseline round-trip time, the connectivity status is connected, and the load level is less than or equal to 0.8 times the link's rated capacity; the conditions for a degraded level are that the smoothed packet loss rate is greater than the first packet loss threshold and less than or equal to a preset second packet loss threshold, or the smoothed round-trip time is greater than 1.5 times the baseline round-trip time and the connectivity status is connected; the conditions for an interrupted level are that the smoothed packet loss rate is greater than the second packet loss threshold, or the round-trip time times out, or the connectivity status is disconnected.

5. A reliable telegraph transmission method for marine dual-redundant networks according to claim 4, characterized in that, The preset strategy table includes the following: When the quality levels of both Link A and Link B are good, urgent and emergency messages are sent via Link A, and general messages are sent via Link B without backoff; when Link A is declining and Link B is good or declining, urgent messages are sent in parallel on both Link A and Link B without backoff, and emergency messages are switched to Link B when the load level of Link B is lower than the handover acceptance threshold, otherwise they are still sent via Link A with an extended confirmation message waiting timeout and a temporary suspension of the first release of new emergency messages, and general messages are completely backoffed; when Link A is interrupted and Link B is available, all messages are resent to Link B, and probe frames are continuously sent on Link A; when both Link A and Link B are interrupted, all unacknowledged messages are kept in the local persistent storage medium, and probe frames are alternately sent on Link A and Link B. The probe frame contains a probe flag, a sending timestamp, and a cyclic redundancy check code. When a link receives confirmation messages corresponding to probe frames that have been successfully sent for a preset number of consecutive times, the corresponding link is determined to have recovered.

6. A reliable telegraph transmission method for marine dual-redundancy networks according to claim 5, characterized in that, The threshold for the number of missing segments is equal to the efficiency coefficient multiplied by the total number of segments. The efficiency coefficient is a preset constant greater than 0 and less than 1, representing the ratio of the equivalent overhead of segment-by-segment retransmission to the overhead of full-report retransmission. When the number of missing segments is greater than the threshold number of missing segments, the sending end performs the full packet retransmission, and the receiving end clears the existing received bitmap and re-verifies each segment after receiving the full packet retransmission. When the number of missing segments is less than or equal to the threshold number of missing segments, the missing segment content read by the sending end from the local persistent storage medium is repackaged and sent to the sending queue, and segments that are not zero in the receiving bitmap are not retransmitted.

7. A reliable telegraph transmission method for marine dual-redundant networks according to claim 6, characterized in that, The sending end performs differentiated backoff based on the message priority and the link quality level: Urgent messages do not perform backoff waiting under any link quality level; urgent messages do not backoff when the link quality level is good, and the backoff waiting time during a decline is equal to the base backoff time multiplied by 2 raised to the power of the current retransmission count, multiplied by the urgent message backoff growth factor, where the urgent message backoff growth factor is greater than 1; general messages, when the link quality level is declining, have a backoff waiting time equal to the base backoff time multiplied by 2 raised to the power of the current retransmission count, and perform complete backoff; when the link quality level is interrupted, they enter persistent waiting; urgent messages have no limit on the number of retransmissions; urgent messages stop retransmission and retain message alarms when they reach the preset maximum number of urgent message retransmissions; general messages stop retransmission and discard messages when they reach the preset maximum number of general message retransmissions.

8. A reliable telegraph transmission method for marine dual-redundant networks according to claim 7, characterized in that, The sending end establishes a persistent record in the local persistent storage medium using the composite key message identifier number plus the receiving end identifier number. The persistent record includes complete message data, segmentation information, retransmission status bitmap, timestamp group, and message priority. The segmentation information records the segmentation granularity, total number of segments, and a list of cyclic redundancy check values ​​for each data segment. The retransmission status bitmap records the acknowledgment status and retransmission count of each data segment. When the sending end restarts, it scans the local persistent storage directory, parses each persistent record, reconstructs the retransmission task in descending order of message priority and ascending order of message creation time, and resumes transmission according to the preset strategy table based on the link quality levels of the current link A and link B. When the used storage space exceeds the preset high watermark, messages with a general priority that have exceeded the preset maximum transmission time limit are first discarded, followed by messages with an urgent priority that have exceeded the time limit. Messages with an extremely urgent priority are not automatically discarded due to timeout.

9. A reliable telegraph transmission method for marine dual-redundant networks according to claim 8, characterized in that, When the same message is sent to multiple receivers, the sending end establishes a group acknowledgment table, which includes a list of group members and the acknowledgment status of each member. The acknowledgment status of each member includes three states: received, partially received, and unacknowledged. The sending end also maintains a missing segment bitmap, the number of retransmissions, the most recent acknowledgment time, and the remaining backoff waiting time. The sending end does not send retransmission segments to receivers that have received the message, only retransmits the missing segments to receivers that have received the message partially, and retransmits all data segments to receivers that have not acknowledged the message. The sending end first sends the main text and attachment index via broadcast, and then retransmits the missing attachment segments of each receiver based on the differences in the received bitmaps reported by each receiver. The number of retransmissions for each receiver is counted independently.

10. A reliable telegraph transmission system for marine dual-redundant networks, characterized in that, include: Enqueue persistence module: The sending end queues messages into the urgent queue, the priority queue, or the general queue according to the message priority and writes them synchronously to the local persistent storage medium; Message segmentation module: The sending end concatenates the main text and attachments in sequence, records the attachment index, and then segments the data into data segments according to the segmentation granularity. Each data segment is appended with a message identifier number, segment number, total number of segments, data payload, and cyclic redundancy check code. Link scheduling module: The sending end selects the sending link and backoff strategy from the preset strategy table according to the link quality level and message priority of link A and link B; Bitmap feedback module: The receiving end performs cyclic redundancy check on the data segment and updates the received bitmap, and appends the received bitmap snapshot to the message body of the acknowledgment / denial message and sends it back to the sending end; Selective retransmission module: The sending end parses the received bitmap to locate missing segments. When the number of missing segments is greater than the missing segment threshold, the entire segment is retransmitted; otherwise, selective retransmission is performed. The missing segment threshold is equal to the efficiency coefficient multiplied by the total number of segments. Backoff decision module: The sender decides whether to backoff based on the message priority and link quality level. Messages with normal priority will be fully backed off when the link quality level is reduced or interrupted.

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