A forwarding control method of a shipborne AIS message data forwarding device

Abstract

This invention discloses a forwarding control method for a shipborne AIS message data forwarding device, belonging to the field of digital information transmission. The forwarding device includes a data receiving module, a central processing module, and a communication module. The forwarding control method includes: S1, the data receiving module continuously receives the AIS message data and sends it to the central processing module for processing; S2, the central processing module determines whether the received AIS message data contains SN4 packets. If so, the AIS message data is discarded; otherwise, the AIS message data is forwarded to the AIS data management center through the communication module. This invention, by real-time monitoring of SN4 packets from AIS base stations, determines whether the ship has entered the effective coverage area of ​​the AIS base station, thereby automatically starting and stopping the AIS message data forwarding function, effectively avoiding data redundancy and significantly saving communication costs.

Description

Technical Field

[0001] This invention relates to the field of Automatic Identification Systems (AIS) for ships, and in particular to a forwarding control method for a shipborne AIS message data forwarding device. Background Technology

[0002] The Automatic Identification System (AIS) is a shipboard broadcast-response system that allows ships to continuously transmit their identity data to nearby vessels and AIS base stations via a public VHF radio channel. As a general-purpose ship identification system, AIS enables real-time navigation communication between ships and between ships and AIS base stations. Without human intervention, it proactively transmits static information (such as MMSI code and ship name), dynamic information (such as latitude, longitude, speed, and heading), and other relevant information to other ships and AIS base stations. Furthermore, it automatically receives and processes real-time navigation information from other ships or navigational aids from AIS base stations. While acquiring information, it is relatively less affected by distance, environment, and speed, thus reducing the likelihood of collisions and ensuring navigational safety.

[0003] Limited by geographical environment and base station deployment costs, AIS signal reception remains poor and message loss rates are high in some remote and special waters, such as the vast open sea and ocean, creating regulatory "blind spots." These "blind spots" in AIS base station coverage can lead to disruptions in the ship dynamic information chain.

[0004] To address the shortcomings of the Automatic Identification System (AIS) and improve the coverage of AIS message data, this invention proposes a forwarding control method based on a shipborne AIS message data forwarding device. This device transforms ships navigating in AIS base station signal coverage blind spots into mobile "data acquisition and forwarding nodes." The forwarding control method avoids the shipborne AIS message data forwarding device from continuously forwarding received AIS message data to the AIS data management center once activated, thus preventing severe data redundancy caused by forwarded AIS message data. Summary of the Invention

[0005] The purpose of this invention is to propose a forwarding control method for a shipborne AIS message data forwarding device. When a ship enters the signal coverage blind zone of an AIS base station, the shipborne AIS message data forwarding device will automatically turn on and send AIS message data to the AIS data management center. When the ship enters the signal coverage area of ​​an AIS base station, the shipborne AIS message data forwarding device will automatically turn off the AIS message data forwarding function, thereby achieving dynamic monitoring of the ship throughout the entire waterway and the entire process without generating AIS message data redundancy.

[0006] To achieve the above objectives, the present invention provides a forwarding control method for a shipborne AIS message data forwarding device, wherein the forwarding device comprises:

[0007] The data receiving module is connected to the AIS shipboard equipment to receive AIS message data in real time.

[0008] A central processing module, which is connected to the data receiving module, processes the received AIS message data;

[0009] A communication module, which is connected to the central processing module, is used to forward the AIS message data to the AIS data management center through the communication network;

[0010] The forwarding control method includes:

[0011] S1. The data receiving module continuously receives the AIS message data and sends it to the central processing module for processing;

[0012] S2. The central processing module determines whether the received AIS message data contains message number 4. If so, the AIS message data is discarded; otherwise, the AIS message data is forwarded to the AIS data management center through the communication module.

[0013] If the judgment result of step S2 is yes, then the process further includes step S31, which is:

[0014] Determine whether the MMSI code in message 4 belongs to a legitimate AIS base station;

[0015] If so, discard the AIS message data, or make further judgments on whether message No. 4 belongs to a legitimate AIS base station;

[0016] If not, the AIS message data will be forwarded to the AIS data management center via the communication module.

[0017] In one embodiment of the present invention, step S31, further determining whether the No. 4 message belongs to a legitimate AIS base station, includes step S32, which is as follows:

[0018] Determine whether the latitude and longitude coordinates of the AIS base station in the No. 4 message are within the water area of ​​the preset geofence;

[0019] If so, then discard the AIS message data;

[0020] If not, the AIS message data will be forwarded to the AIS data management center via the communication module.

[0021] As one embodiment of the present invention, it further includes step S4, wherein step S4 is:

[0022] The current operating mode of the forwarding device is determined, and the time distribution characteristics of the No. 4 message are analyzed based on the operating mode. Based on the time distribution characteristics, the forwarding device performs an action to maintain or switch the current mode.

[0023] As one embodiment of the present invention, if the forwarding device is currently in the mode of forwarding AIS message data, the receiving time of the No. 4 message is recorded, and the number of the No. 4 messages within a first preset time period before the current working time of the forwarding device is counted.

[0024] As one embodiment of the present invention, it is determined whether the number of the fourth message is greater than a first preset threshold.

[0025] If so, the forwarding device switches to a mode that discards the AIS message data;

[0026] If not, the forwarding device continues to forward the AIS message data.

[0027] As one embodiment of the present invention, if the forwarding device is currently in the mode of discarding AIS message data, the reception time of message No. 4 is recorded, and the latest reception time in the recorded message No. 4 is queried.

[0028] As one embodiment of the present invention, it is determined whether the latest reception time in the No. 4 message is within a second preset time period before the current working time of the forwarding device;

[0029] If so, the forwarding device will maintain the mode of discarding AIS packet data;

[0030] If not, the forwarding device switches to the mode of forwarding AIS message data.

[0031] In one embodiment of the present invention, the communication module forwards the AIS message data to the AIS data management center via a cellular network or a wired network.

[0032] As one embodiment of the present invention, the shipborne AIS message data forwarding device further includes a power supply module for supplying power to the data receiving module, the central processing module, and the communication module.

[0033] The forwarding control method for shipborne AIS message data forwarding equipment provided by this invention has the following advantages:

[0034] This invention proposes a forwarding control method for a shipborne AIS message data forwarding device, which solves the problems of insufficient signal coverage and low message reception rate of AIS base stations in certain waters. On the one hand, this invention intelligently determines whether the ship has entered the effective coverage range of the AIS base station by real-time monitoring of the AIS base station's SN4 message, thereby automatically starting and stopping the AIS message data forwarding function, effectively avoiding data redundancy, significantly saving communication costs, and significantly reducing the processing load of the AIS data management center. On the other hand, this invention reads the shipborne AIS terminal data in real time through the serial port and forwards the data to the AIS data management center using 4G or Ethernet, filling the coverage blind spots of the AIS base station and realizing dynamic monitoring of the ship throughout the entire waterway and process. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the shipborne AIS message data forwarding device of the present invention. Detailed Implementation

[0036] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0037] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0038] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0039] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0040] The forwarding control method for shipborne AIS packet data forwarding equipment proposed in this invention is based on the shipborne AIS packet data forwarding equipment. See [link to relevant documentation]. Figure 1 The shipborne AIS message data forwarding equipment includes a data receiving module, a central processing module, a communication module, and a power supply module.

[0041] The data receiving module connects to the AIS shipboard equipment to receive AIS message data in real time. The data receiving module uses a standard serial port to connect to the existing AIS shipboard equipment and reads the AIS message data output by the equipment in real time.

[0042] The central processing module, connected to the data receiving module, processes the AIS message data. The central processing module employs an embedded microprocessor (MCU / CPU) responsible for parsing the received AIS message data, performing time stamping on the AIS message data, and then buffering and packaging it.

[0043] A communication module, connected to the central processing module, is used to forward the AIS message data to the AIS data management center via a communication network. The communication module forwards the AIS message data to the AIS data management center via a cellular network or a wired network. For example, the communication module integrates a 4G / 5G wireless communication device and / or an Ethernet interface. When 4G / 5G signals are available, it prioritizes sending the AIS message data to the AIS data management center via the 4G / 5G network. When at port or with wired network access, it can switch to sending the AIS message data to the AIS data management center via Ethernet, providing a more stable and economical transmission channel.

[0044] The shipborne AIS message data forwarding equipment includes two modes: forwarding AIS message data and discarding AIS message data. After the central processing module parses, marks, buffers, and packages the AIS message data received from the shipborne AIS equipment via the data receiving module, the communication module, in forwarding mode, forwards the AIS message data to the AIS data management center. In discarding mode, the communication module does not forward the AIS message data to the AIS data management center.

[0045] The power module supplies power to the data receiving module, the central processing module, and the communication module. The power module supports wide-voltage input marine power and provides necessary indicator lights to display device operation, network connection, and data forwarding modes.

[0046] The forwarding control method for shipborne AIS message data forwarding equipment includes the following steps:

[0047] S1. The data receiving module continuously receives AIS message data and sends it to the central processing module for processing.

[0048] When a ship enters the signal coverage area of ​​an AIS base station, the AIS message data sent by the shipborne AIS equipment will be received by the AIS base station. After receiving the AIS message data from the ship within its coverage area, the AIS base station will upload the received AIS message data to the AIS data management center. If the shipborne AIS message data forwarding equipment is also forwarding AIS message data to the AIS data management center at the same time, the same AIS message data will be uploaded to the AIS data management center through both the shipborne AIS message data forwarding equipment and the AIS base station, resulting in serious data redundancy and increasing the data load on the AIS data management center.

[0049] To address the aforementioned issues, this invention provides a system where the shipborne AIS message forwarding device discards AIS message data when the ship is within the signal coverage area of ​​an AIS base station, thus avoiding data redundancy. When the ship leaves the signal coverage area of ​​the AIS base station and enters a "blind zone," the shipborne AIS message forwarding device resumes forwarding AIS message data, enabling the AIS data management center to obtain the ship's AIS message data in real time even when the ship is in a "blind zone." To achieve precise control of the shipborne AIS message forwarding device between forwarding and discarding modes, the following steps are employed to implement the above functions:

[0050] S2. The central processing module determines whether the received AIS message data contains message number 4. If so, the AIS message data is discarded; otherwise, the AIS message data is forwarded to the AIS data management center through the communication module.

[0051] The specific meanings of the main AIS messages are shown in Table 1 below:

[0052] Table 1. AIS Message Interpretation Table

[0053] ID name illustrate 1 Location report Arranged location report 2 Location report Location report of assigned arrangements 3 Location report Special location report, respond to inquiries 4 Base station report Base station location, UTC, date, and current timeslot number

[0054] In the Automatic Identification System (AIS), Message No. 4 is unique to AIS base stations. AIS base stations periodically broadcast Message No. 4 to announce their presence and operating mode. When a ship is within the signal coverage area of ​​an AIS base station, the shipborne AIS message data forwarding device can receive the Message No. 4 transmitted by the AIS base station. Therefore, the shipborne AIS message data forwarding device of this invention can use the receipt of Message No. 4 from a legitimate base station as a reliable indicator of whether a ship has entered the signal coverage area of ​​an AIS base station. The shipborne AIS message data forwarding device of this invention connects to the shipborne AIS equipment through a data receiving module. The forwarding device can obtain Message No. 4 and perform operations such as forwarding or discarding AIS message data based on Message No. 4.

[0055] In a more preferred embodiment, to prevent misjudgment caused by maliciously generated SS4 packets from other ships or illegal AIS base stations, the shipborne AIS packet data forwarding device must determine the validity of the received SS4 packets. The forwarding control method of the present invention further includes: if the determination result of step S2 is yes, then it further includes step S31, which is:

[0056] Determine whether the MMSI code in message 4 belongs to a legitimate AIS base station;

[0057] If so, discard the AIS message data, or make further judgments on whether the No. 4 message belongs to a legitimate AIS base station;

[0058] If not, the AIS message data will be forwarded to the AIS data management center via the communication module.

[0059] The Maritime Mobile Service Identity (MMSI) is a crucial component of the Automatic Identification System (AIS). Within AIS, the MMSI is a nine-digit unique identifier assigned by the International Maritime Organization (IMO) to a vessel or AIS base station, serving as the fundamental basis for identifying and tracking ships. Message No. 4 contains the MMSI code of the AIS base station that transmitted the message. According to maritime regulations, legitimate AIS base stations typically have MMSI codes that begin with specific numbers, such as 00412, 00413, or 00414. Message No. 4 messages from such legitimate base stations will be considered valid; otherwise, they will be invalid and ignored.

[0060] As a preferred implementation, to further enhance the accuracy of the validity determination of message 4, after determining that the MMSI code in message 4 belongs to a legitimate AIS base station, a further determination of whether message 4 belongs to a legitimate AIS base station is made, including step S32, which is as follows:

[0061] Determine whether the latitude and longitude coordinates of the AIS base station in message 4 are within the water area of ​​the preset geofence;

[0062] If so, discard the AIS message data;

[0063] If not, the AIS message data will be forwarded to the AIS data management center via the communication module.

[0064] This invention further sets up a geofence, so that the No. 4 message is only considered valid when the location information of the AIS base station contained in the No. 4 message, such as the latitude and longitude coordinates, is within the water area of ​​the preset geofence.

[0065] Therefore, the validity determination of message 4 in this invention can be as follows: First, the shipborne AIS message data forwarding device parses the MMSI code and / or location information of the AIS base station from the received message 4, and compares the MMSI code of message 4 with a preset list of valid base station MMSI code prefixes (such as 00412, 00413, 00414). If the MMSI code does not conform to this rule, message 4 will be immediately determined to be invalid and discarded directly, without further processing. If message 4 passes the MMSI code verification, an optional second-layer verification, namely geofence verification, will be performed. In this verification, the latitude and longitude information of the AIS base station is combined to determine whether its location falls within the water area of ​​a preset geofence. If the location of the AIS base station is not within the water area of ​​the preset geofence, message 4 is also considered invalid. If the location of the AIS base station is within the water area of ​​the preset geofence, message 4 is valid. After adding geofence verification, only message #4 that passes both MMSI code verification and geofence verification will be ultimately confirmed as a valid message.

[0066] Furthermore, after obtaining a valid Message No. 4, the present invention can perform actions to maintain or switch the current operating mode of the communication module based on Message No. 4. Specifically, the present invention employs the following steps:

[0067] The process further includes step S4, which is as follows:

[0068] Determine the current operating mode of the forwarding device, analyze the time distribution characteristics of message No. 4 based on the operating mode, and perform the action of maintaining or switching the current mode based on the time distribution characteristics.

[0069] The forwarding control method of this invention can analyze the time distribution characteristics of valid .4 packets using different methods according to the current operating mode of the forwarding device, and perform different operations based on the time distribution characteristics. Specifically, it includes:

[0070] (1) If the forwarding device is currently in AIS message data forwarding mode, record the reception time of message No. 4, and count the number of message No. 4 received within the first preset time period before the current working time of the forwarding device. That is, based on the current working time of the shipborne AIS message data forwarding device, count the number of valid message No. 4 received by the shipborne AIS message data forwarding device within the first preset time period (e.g., 10 minutes) before the benchmark.

[0071] Determine whether the number of messages No. 4 exceeds the first preset threshold;

[0072] If so, the forwarding device switches to the mode of discarding AIS packet data;

[0073] If not, the forwarding device will continue to forward AIS message data.

[0074] Within a first preset time period (e.g., 10 minutes) before the current operating time of the shipborne AIS message data forwarding equipment, if the number of valid .4 packets received by the forwarding equipment exceeds a first preset threshold (e.g., 5 times), it reliably indicates that the ship has entered the signal coverage area of ​​the AIS base station. At this time, the forwarding equipment switches to a mode that discards AIS message data, thereby avoiding receiving redundant AIS message data at the AIS data management center. If the number of valid .4 packets received by the forwarding equipment is less than the first preset threshold (e.g., 5 times), it cannot reliably indicate that the ship has entered the signal coverage area of ​​the AIS base station, and the forwarding equipment needs to maintain the mode of forwarding AIS message data.

[0075] (2) If the forwarding device is currently in the mode of discarding AIS message data, record the reception time of message No. 4, and query the latest reception time of message No. 4 in the record. That is, based on the current working time of the shipborne AIS message data forwarding device, query the latest reception time of the valid message No. 4 received by the shipborne AIS message data forwarding device that is far from the current working time of the forwarding device.

[0076] Determine whether the latest received time in message No. 4 is within the second preset time period before the current working time of the forwarding device;

[0077] If so, the forwarding device will maintain the mode of discarding AIS packet data;

[0078] If not, the forwarding device switches to the mode of forwarding AIS message data.

[0079] Within a second preset time period (e.g., 15 minutes) before the current operating time of the shipborne AIS message data forwarding equipment, if the latest reception time of a valid No. 4 message falls within this second preset time period, meaning a valid No. 4 message can be received within this second preset time period before the current operating time of the forwarding equipment, it reliably indicates that the ship is still within the signal coverage area of ​​the AIS base station. In this case, the forwarding equipment needs to maintain the mode of discarding AIS message data. Conversely, if the latest reception time of a valid No. 4 message does not fall within this second preset time period, meaning no valid No. 4 message can be received within this second preset time period before the current operating time of the forwarding equipment, it reliably indicates that the ship has left the signal coverage area of ​​the AIS base station. In this case, the forwarding equipment needs to switch to the mode of forwarding AIS message data to ensure that the AIS data management center can obtain the ship's AIS message data in real time when the ship enters a "blind zone".

[0080] Specifically, once the condition for discarding AIS message data is triggered, the shipborne AIS message data forwarding device immediately enters the mode of discarding AIS message data, and the forwarding device discards the AIS message data received by the forwarding data receiving module.

[0081] Specifically, once the conditions for resuming the forwarding of AIS message data are triggered, the shipborne AIS message data forwarding device immediately enters the mode of forwarding AIS message data, and the forwarding device forwards the AIS message data received by the data receiving module to the AIS data management center in real time.

[0082] Therefore, the shipborne AIS message data forwarding device of the present invention, by adopting the above forwarding control method, can achieve the following effects:

[0083] (1) When a ship enters a blind area with insufficient AIS base station signal coverage and low message reception rate, the AIS message data forwarding mode is automatically enabled to continuously forward the ship's AIS message data to the AIS data management center, thereby realizing dynamic supervision of the ship throughout the entire water area and process, filling the supervision gap in the signal coverage blind area of ​​AIS base station, and improving the supervision capability of the ship.

[0084] (2) When a ship enters the effective coverage area of ​​an AIS base station, since the ship's AIS message data can be directly captured by the AIS base station, switching to a mode that discards AIS message data avoids the same AIS message data from the same ship being repeatedly reported to the AIS data management center via two paths: the AIS base station and the ship's AIS message data forwarding equipment. This avoids data redundancy and reduces the data processing load on the AIS data management center. In contrast, if the ship's AIS message data forwarding equipment is always in the mode of forwarding AIS message data regardless of whether it is within the effective coverage area of ​​the AIS base station, the resulting massive amount of redundant data will put enormous processing, filtering, and storage pressure on the AIS data management center.

[0085] (3) When the ship is in the signal coverage blind zone of the AIS base station, the AIS message data is sent to the AIS data management center through the shipborne AIS message data forwarding equipment. When the ship is in the signal coverage area of ​​the AIS base station, the AIS message data is sent to the AIS data management center only through the AIS base station. Thus, the AIS data management center can obtain the ship's AIS message data in both the signal coverage area and the blind zone of the AIS base station.

[0086] Furthermore, the shipborne AIS message data forwarding device of the present invention mainly transmits data through cellular networks such as 4G and 5G mobile networks, which has a fast transmission speed. Moreover, the forwarding device only activates the cellular network to transmit message data when the ship enters the signal blind zone of the AIS base station, which greatly reduces data traffic and significantly reduces long-term operating costs for ship owners or managers.

[0087] In summary, the forwarding control method of the shipborne AIS message data forwarding device of the present invention can automatically control the forwarding and discarding of AIS message data. It not only solves the problem that the AIS data management center cannot obtain the ship's AIS message data when the ship is in the signal coverage blind zone of the AIS base station, but also effectively solves the problems of AIS message redundancy, high communication costs and heavy load on the AIS data management center that may be caused by the continuous forwarding of AIS message data by the forwarding device when the ship is in the signal coverage area of ​​the AIS base station.

[0088] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make several improvements and substitutions without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A retransmission control method of a shipboard AIS message data retransmission device, characterized by, The forwarding device includes: The data receiving module is connected to the AIS shipboard equipment to receive AIS message data in real time. A central processing module, which is connected to the data receiving module, processes the received AIS message data; A communication module, which is connected to the central processing module, is used to forward the AIS message data to the AIS data management center through the communication network; The forwarding control method includes: S1. The data receiving module continuously receives the AIS message data and sends it to the central processing module for processing; S2. The central processing module determines whether the received AIS message data contains message number 4. If so, the AIS message data is discarded; otherwise, the AIS message data is forwarded to the AIS data management center through the communication module. If the judgment result of step S2 is yes, then the process further includes step S31, which is: Determine whether the MMSI code in message 4 belongs to a legitimate AIS base station; If so, discard the AIS message data, or make further judgments on whether message No. 4 belongs to a legitimate AIS base station; If not, the AIS message data is forwarded to the AIS data management center via the communication module. In step S31, further determining whether message number 4 belongs to a legitimate AIS base station includes step S32, which is as follows: Determine whether the latitude and longitude coordinates of the AIS base station in the No. 4 message are within the water area of ​​the preset geofence; If so, then discard the AIS message data; If not, the AIS message data is forwarded to the AIS data management center via the communication module. The method further includes step S4, which is: The current operating mode of the forwarding device is determined, and the time distribution characteristics of the No. 4 message are analyzed based on the operating mode. Based on the time distribution characteristics, the forwarding device performs an action to maintain or switch the current mode.

2. The forwarding control method according to claim 1, characterized in that, If the forwarding device is currently in the mode of forwarding AIS message data, record the reception time of message No. 4, and count the number of messages No. 4 within a first preset time period before the current working time of the forwarding device.

3. The forwarding control method according to claim 2, characterized in that, Determine whether the number of the fourth message is greater than a first preset threshold; If so, the forwarding device switches to a mode that discards the AIS message data; If not, the forwarding device continues to forward the AIS message data.

4. The forwarding control method according to claim 1, characterized in that, If the forwarding device is currently in the mode of discarding AIS message data, record the reception time of message No. 4, and query the latest reception time in the recorded message No.

4.

5. The forwarding control method according to claim 4, characterized in that, Determine whether the latest reception time in the No. 4 message is within a second preset time period before the current working time of the forwarding device; If so, the forwarding device will maintain the mode of discarding AIS packet data; If not, the forwarding device switches to the mode of forwarding AIS message data.

6. The forwarding control method according to claim 1, characterized in that, The communication module forwards the AIS message data to the AIS data management center via a cellular network or a wired network.

7. The forwarding control method according to claim 1, characterized in that, The shipborne AIS message data forwarding device also includes a power module for supplying power to the data receiving module, the central processing module, and the communication module.

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