AIS message delivery method, device and equipment under high-density base station cluster and storage medium

Abstract

The invention provides an AI message delivery method, device and equipment under a high-density base station cluster and a storage medium, and the method comprises the steps: firstly obtaining an AI message received by an AI base station in a coverage range, analyzing the AI message to generate motion data of a ship, and predicting a motion track of the ship in a future preset duration according to the motion data of the ship; then, evaluating the communication quality between the generated ship and the base station based on the sending and receiving time of the AI message, the sending and receiving confirmation time of the binary short message and the retransmission times; then, according to the motion trail of the ship in the future preset duration and the communication quality between the ship and the base station, an optimal sending link of the ship in the future preset duration is generated; finally, the VHF time slot occupancy rate and the message sending task queue of the AI base station are monitored in real time, the current base station load state is generated, the optimal base station is selected based on the optimal sending link and the base station load state for signal emission, and the air signal load occupied by message sending is reduced.

Description

Technical Field

[0001] The present invention relates to the field of shipping, and in particular to an AIS message delivery method, device, equipment and storage medium under a high-density base station cluster. Background Art

[0002] AIS (Automatic Identification System) is composed of shore-based facilities and ship-borne equipment. It is a digital navigation aid system that integrates network, communication, computer and electronic display technology. AIS can be connected with radar, ARPA, ECDIS, VTS and other systems to jointly build a maritime traffic management and monitoring network. In this system, static information of ships such as nine-digit codes and ship names are crucial, which directly affect the navigation safety of ships and maritime traffic control dispatch. AIS base stations communicate with ships through the VHF frequency band, which can not only monitor the activities of ships, but also actively obtain dynamic information and other relevant data of ships. In order to enhance the communication capability between base stations and ships, we will deploy AIS base stations at a high density on the coast to increase the signal strength in the coverage area. However, in the high-density base station coverage area, the selection of base stations needs to take into account a variety of factors, including signal coverage range, ship distribution density, communication load balancing and environmental interference. In addition, the dynamic changes in ship position and navigation status further increase the complexity of base station selection.

[0003] In view of this, this application is filed. Summary of the invention

[0004] The invention discloses an AIS message delivery method, device, equipment and storage medium under a high-density base station cluster, aiming to reduce the air signal load occupied by sending messages.

[0005] The first invention of the present invention provides an AIS message delivery method under a high-density base station cluster, comprising:

[0006] Acquire an AIS message received by an AIS base station within its coverage area, parse the AIS message to generate ship motion data, and predict the movement trajectory of the ship within a preset time period in the future based on the ship motion data;

[0007] The communication quality between the ship and the base station is evaluated and generated based on the sending and receiving time of the AIS message, the sending and receiving confirmation time of the binary short message and the number of retransmissions;

[0008] Generate an optimal transmission link for the ship within a preset time period in the future according to the movement trajectory of the ship within a preset time period in the future and the communication quality between the ship and the base station;

[0009] The VHF time slot occupancy rate and message sending task queue of the AIS base station itself are monitored in real time to generate the current base station load status, and the optimal base station is selected for signal transmission based on the optimal sending link and the base station load status.

[0010] Preferably, the obtaining of an AIS message received by an AIS base station within its coverage, parsing the AIS message to generate the motion data of the ship, and predicting the motion trajectory of the ship within a preset time period in the future according to the motion data of the ship, is specifically as follows:

[0011] After receiving the AIS message, the AIS message is parsed and filtered according to the AIS message protocol to generate filtered motion data;

[0012] Calculate the motion trajectory within a preset time period in the future according to the filtered motion data. Specifically, calculate the motion trend of the ship in the future according to the motion trends at three time points in the history of the ship, wherein the motion trend includes the motion acceleration alon and the motion acceleration alat;

[0013]

[0014] Prediction at t feature The calculation formula of time is as follows:

[0015]

[0016] Among them, lon history3 is the longitude value at the time of history3, lat history3 is the latitude value at the time of history3, vlon history3 is the speed value in the longitude direction at the time of history3, vlat hisrory3 is the velocity value in the latitude direction at the time of history3, t feature is the time of feature moment, t history3 is the time of history3, alon is the acceleration in the longitude direction, alat is the acceleration in the latitude direction, lon featrue The longitude value at the feature time, lat featrue The latitude value at the feature time.

[0017] Preferably, the filtering comprises:

[0018] When a trajectory reversal point appears, determine whether the next point moves in the reversal direction, if not, remove the current point;

[0019] When a speed-increasing point appears, the motion acceleration is calculated, and when the motion acceleration exceeds a threshold value set according to the ship type, the point is eliminated;

[0020]

[0021] Among them, Δlat is the change in latitude, Δlon is the change in longitude, R is the average radius of the earth, arcsin represents the inverse sine function, Δs is the moving distance, a is the acceleration, and Δt is the time difference between two points.

[0022] Preferably, the communication quality between the ship and the base station is evaluated and generated based on the sending and receiving time of the AIS message, the sending and receiving confirmation time of the binary short message, and the number of retransmissions, specifically:

[0023] Extract the ship position report in the AIS message, save the area where the ship is located and the source AIS base station information, parse the UTC second data in the ship position report and the UTC second data when the position report is received, and record the communication delay;

[0024] Record the time when the ship sends the binary short message, the time when the ship receives the binary confirmation message in response, and the number of times the binary short message is resent, and generate statistics on the message trigger success rate;

[0025] A communication quality is generated based on the communication delay and the message touch-off success rate.

[0026] Preferably, the step of generating the best transmission link for the ship within a preset time period in the future according to the movement trajectory of the ship within a preset time period in the future and the communication quality between the ship and the base station is specifically as follows:

[0027] The ship communication quality score under the base station is calculated according to the communication delay and the message touch success rate, and its expression is:

[0028]

[0029] Where, mmsi is the user ID value in the location report, UTCreceive is the UTC second of the received location report, UTCsend is the UTC second in the location report data, frquencyOfReception is the number of received location reports, Tsend is the binary short message sending time, Treply is the time when the binary confirmation reply is received, RetryTimes is the sum of the historical retries of sending short messages, times is the number of historical short message sending times, α, β, γ are data weight values ​​used to adjust the impact of sample size differences on unbalanced samples;

[0030] A short message routing table of the ship is generated according to the communication quality score and the historical position information of the ship. According to the priority records in the short message routing table and in combination with the communication needs of a preset time in the future, the best sending link is dynamically adjusted and determined.

[0031] Preferably, the selecting the optimal base station for signal transmission based on the optimal transmission link and the base station load state is specifically:

[0032] Based on the speed and heading in the motion data and the short message routing table, a list of base stations that need to be transmitted is calculated, and the calculation process is:

[0033]

[0034] Wherein, d(i) is a record of the short message routing table that meets the conditions, sog is the speed information in the position report, cog is the ground route information in the position report, and msgType is the message type;

[0035] According to the base station status information, and when it is detected that the operating load of the base station reaches a preset percentage of its rated working capacity, the next available base station located in the direction of the ship's travel is selected from the base station list to continue the message transmission task.

[0036] Preferably, the selecting the next available base station located in the traveling direction of the ship from the base station list to continue the message transmission task is specifically:

[0037] When it is determined that the speed sog is less than Vset, the calculation expression of the next available base station is as follows:

[0038]

[0039] Wherein, f2(mmsi,msgType) is the base station expected to be delivered obtained through mmsi and message type, d(j) is a record of the short message routing table that meets the conditions, and Vset is the speed preset value based on the performance of the base station;

[0040] When the speed sog ≥ Vset, the calculation expression of the next available base station is as follows:

[0041]

[0042] The time slot is reserved through the base station. If the reservation fails, the message is still sent according to the next base station in the direction of the ship's movement. The calculation expression is as follows:

[0043]

[0044] Among them, Sload is the base station load, Reservation is the reservation result, 1 is success, 0 is failure, and the selection is made according to the direction of movement of the ship. d(k+1) indicates that the next adjacent node is selected according to the direction of movement of the ship.

[0045] A second aspect of the present invention provides an AIS message delivery device under a high-density base station cluster, comprising:

[0046] A motion trajectory prediction unit is used to obtain an AIS message received by an AIS base station within its coverage area, parse the AIS message to generate motion data of the ship, and predict the motion trajectory of the ship within a preset time period in the future based on the motion data of the ship;

[0047] A communication quality evaluation unit, used to evaluate the communication quality between the ship and the base station based on the sending and receiving time of the AIS message, the sending and receiving confirmation time of the binary short message and the number of retransmissions;

[0048] An optimal transmission link determination unit, configured to generate an optimal transmission link for the ship within a preset time period in the future according to a movement trajectory of the ship within a preset time period in the future and a communication quality between the ship and a base station;

[0049] The dynamic adjustment unit is used to monitor the VHF time slot occupancy rate and message sending task queue of the AIS base station itself in real time, generate the current base station load status, and select the optimal base station for signal transmission based on the optimal sending link and the base station load status.

[0050] A third aspect of the present invention provides an AIS message delivery device in a high-density base station cluster, comprising a memory and a processor, wherein the memory stores a computer program, and the computer program can be executed by the processor to implement an AIS message delivery method in a high-density base station cluster as described in any one of the above items.

[0051] A fourth aspect of the present invention provides a computer-readable storage medium, characterized in that a computer program is stored therein, and the computer program can be executed by a processor of a device where the computer-readable storage medium is located to implement an AIS message delivery method under a high-density base station cluster as described in any one of the above items.

[0052] Based on the AIS message delivery method, device, equipment and storage medium under a high-density base station cluster provided by the present invention, the AIS message received by the AIS base station within its coverage is first obtained, the AIS message is parsed to generate the motion data of the ship, and the motion trajectory of the ship within a preset time period in the future is predicted based on the motion data of the ship; then, the communication quality between the ship and the base station is evaluated and generated based on the sending and receiving time of the AIS message, the sending and receiving confirmation time of the binary short message and the number of retransmissions; then, the best sending link for the ship within the preset time period in the future is generated based on the motion trajectory of the ship within the preset time period in the future and the communication quality between the ship and the base station; finally, the VHF time slot occupancy rate and the message sending task queue of the AIS base station itself are monitored in real time to generate the current base station load state, and the optimal base station is selected for signal transmission based on the best sending link and the base station load state, thereby reducing the air signal load occupied by sending messages. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 It is a flowchart of an AIS message delivery method in a high-density base station cluster provided by the first embodiment of the present invention;

[0054] Figure 2 The present invention provides a disassembly schematic diagram of the ship's movement direction;

[0055] Figure 3 It is a module schematic diagram of an AIS message delivery device in a high-density base station cluster provided by the second embodiment of the present invention. DETAILED DESCRIPTION

[0056] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0057] In order to better understand the technical solution of the present invention, the embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0058] It should be clear that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0059] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0060] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0061] The word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)", depending on the context.

[0062] The "first\second" mentioned in the embodiments is only to distinguish similar objects, and does not represent a specific order for the objects. It is understandable that the "first\second" can be interchanged with the specific order or sequence where permitted. It should be understood that the objects distinguished by "first\second" can be interchanged where appropriate, so that the embodiments described herein can be implemented in an order other than those illustrated or described herein.

[0063] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0064] The invention discloses an AIS message delivery method, device, equipment and storage medium under a high-density base station cluster, aiming to reduce the air signal load occupied by sending messages.

[0065] See also Figure 1 The first invention of the present invention provides an AIS message delivery method under a high-density base station cluster, which can be executed by an IS message delivery device (hereinafter referred to as a delivery device), and in particular, is executed by one or more processors in the delivery device to at least implement the following steps:

[0066] S101, obtaining an AIS message received by an AIS base station within its coverage area, parsing the AIS message to generate ship motion data, and predicting a movement trajectory of the ship within a preset time period in the future according to the ship motion data;

[0067] In this embodiment, the delivery device may be a server, which can communicate with one or more base stations. The delivery device may be installed with a corresponding operating system and application software, and the functions required by this embodiment are realized through the combination of the operating system and the application software;

[0068] It should be noted that in offshore areas, in order to achieve efficient communication interaction between base stations and shipborne automatic identification system (AIS) equipment, multiple AIS base stations need to be deployed at a high density on the coastline to ensure the stability of communication quality and the continuity of coverage. These base stations communicate with shipborne AIS equipment in the coverage area by transmitting very high frequency (VHF) signals. It is necessary to select the best base station from multiple base stations to work, realize the reasonable allocation and utilization of communication resources, and thus improve the efficiency and stability of the overall communication system. Therefore, an efficient base station selection method or strategy is required.

[0069] Specifically, in order to accurately predict the movement trajectory of a ship within a preset time in the future, it is first necessary to extract valid data from the AIS message received by the AIS base station. Specifically, the AIS base station receives the AIS message sent by the ship within the coverage area, which contains the ship's real-time location information, speed, heading and other movement data. After the received AIS message is parsed by the protocol, the movement data field is extracted. These fields are further cleaned and filtered to ensure that the data is accurate and reliable when used for trajectory prediction.

[0070] In the data filtering process, a mechanism for removing abnormal points is introduced. For example, when a turning point appears in the trajectory, it is determined whether the next point moves in the turning direction. If not, the current point is considered an abnormal point and is removed. Pseudo-trajectories caused by signal interference or positioning errors can be effectively eliminated. In addition, for the speed advance point, the motion acceleration is calculated, and when the motion acceleration exceeds the threshold set according to the ship type, the point is removed. The calculation process is as follows:

[0071]

[0072] Among them, Δlat is the change in latitude, Δlon is the change in longitude, R is the average radius of the earth, arcsin represents the inverse sine function, Δs is the moving distance, a is the acceleration, and Δt is the time difference between two points.

[0073] After completing the data filtering, please combine Figure 2 The ship's motion direction can be divided into motion in the longitude direction and the latitude direction, vlon = v hisotry ×sincog / vlat=v hisotry×coscog, calculates the future motion trajectory of the ship based on historical motion data. Specifically, by extracting the motion information of the ship at three time points in history, including latitude and longitude coordinates, speed and time, its motion trend is analyzed. By fitting and calculating these historical data, the motion trend of the ship within a preset time period in the future is predicted, and the motion trend includes motion acceleration alon and motion acceleration alat;

[0074]

[0075] Prediction at t feature The calculation formula of time is as follows:

[0076]

[0077] Among them, lon history3 is the longitude value at the time of history3, lat history3 is the latitude value at the time of history3, vlon history3 is the speed value in the longitude direction at the time of history3, vlat history3 is the velocity value in the latitude direction at the time of history3, t feature is the time of feature moment, t history3 is the time of history3, alon is the acceleration in the longitude direction, alat is the acceleration in the latitude direction, lon featrue The longitude value at the feature time, lat featrue The latitude value at the feature time. In areas with dense ships, by predicting the movement trajectory of ships in advance, it can provide a key reference for base station scheduling and communication link optimization, thereby improving the overall communication efficiency and reliability of the AIS system.

[0078] S102, evaluating and generating the communication quality between the ship and the base station based on the sending and receiving time of the AIS message, the sending and receiving confirmation time of the binary short message and the number of retransmissions;

[0079] Specifically, after receiving the position report from the ship, the AIS base station will parse it according to the message protocol and extract key information such as the ship's MMSI code, location data and timestamp. This information is used to generate a record of the ship's current location and associate it with the base station information that receives the location report. Subsequently, the delivery device further parses the UTC second data in the location report and records the UTC second data of the message when it is received by the base station. The communication delay is obtained by calculating the time difference between the two, so as to accurately capture the actual delay from the ship's message being sent to being received, and provide basic data for the evaluation of communication quality.

[0080] The delivery device also records the relevant data of the binary short message in real time, including the time when the short message is sent, the time when the ship's response confirmation is received, and the number of retransmissions that may occur during the transmission of the short message. It can be used to evaluate the stability and reliability of the communication link. For example, a longer response time and a higher number of retransmissions indicate that the link is heavily loaded or the environmental interference is large. By comprehensively analyzing these parameters, the success rate of the short message can be calculated. The message success rate is an important indicator for measuring the reliability of the link. It is obtained by counting the ratio of the number of messages sent and successfully received within a period of time, which can intuitively reflect the effectiveness of the link.

[0081] Furthermore, the data center records the source base stations of the ship's position reports and arranges them in reverse order according to the time when the position reports are received. f(m,t)=(m,t), whenever a new position report is received, it is converted into a tuple form and added to the list L. Here m represents the MMSI code of the ship, and t is the timestamp of receiving this report.

[0082] g(L)=L′

[0083] in,

[0084] The elements in L′ are arranged in ascending order according to their corresponding timestamps t.

[0085] When evaluating the communication quality, the two key indicators of communication delay and message contact success rate are combined for comprehensive calculation to generate the communication quality evaluation result. This evaluation result can be expressed in the form of a quality score. The higher the score, the better the performance of the communication link. Through this communication quality evaluation process, the real-time monitoring and dynamic adjustment of the link performance between the ship and the base station can be achieved, especially when the communication load is high, which can significantly reduce the risk of message loss and delay.

[0086] S103, generating an optimal transmission link for the ship within a preset time period in the future according to the movement trajectory of the ship within a preset time period in the future and the communication quality between the ship and the base station;

[0087] It should be noted that during the calculation of the communication quality score, the delivery equipment will collect and update the ship's motion data and historical communication records in real time. For example, for the sending and confirmation time of binary short messages, by accurately recording these time points and the number of retransmissions, the stability of the communication link can be determined. The analysis of the UTC second data of the position report and the UTC second data at the time of reception helps to capture the changing trend of communication delay.

[0088] The expression of communication quality score is:

[0089]

[0090] Where, mmsi is the user ID value in the position report, UTCreceive is the UTC second of the received position report, UTCsend is the UTC second in the position report data, frquencyOfReception is the number of received position reports, Tsend is the binary short message sending time, Treply is the time when the binary confirmation reply is received, RetryTimes is the sum of the number of retries for sending short messages in history, times is the number of short messages sent in history, α, β, γ are data weight values, which depend on the amount of binary short messages and the proportion of ship position reports in specific services, and are used to adjust the impact of sample size differences of unbalanced samples through weight adjustment;

[0091] Based on the above communication quality score and the historical location information of the ship, a short message routing table of the ship is further generated. The specific process may be:

[0092] Let D be a data set, di∈D represents a record in the data set, where each record contains a timestamp ti, a score si, and a user ID mmsii. Given a user ID mmsi and a positive integer n, we want to find the first n records that satisfy mmsii=M and sort them in descending order by timestamp; if the timestamps are the same, they are sorted in descending order by score. Define a function F as follows:

[0093] F(D,M,n)=d(1),d(2),...,d(n)

[0094] Where d(i) is the i-th record selected from D and sorted according to the following rules:

[0095] For all di∈D, di is considered only when mmsii=M.

[0096] If ti>tj, then di comes before dj.

[0097] If ti=tj, and si>sj, then di comes before dj

[0098] If ti = tj and si = sj, the relative order of di and dj does not matter (keep the original order or sort it arbitrarily). Only select the first n records after sorting. If the total number of records is less than n, select all records that meet the conditions.

[0099] Finally, the system dynamically adjusts and determines the best sending link based on the priority records in the short message routing table and the communication needs of the preset time in the future. Specifically, the ship's speed, heading, and the coverage of the base stations it may pass through within the preset time are used to select the optimal path to complete the message transmission.

[0100] S104, real-time monitoring of the VHF time slot occupancy rate and message sending task queue of the AIS base station itself, generating the current base station load status, and selecting the best base station for signal transmission based on the best sending link and the base station load status.

[0101] It should be noted that in order to achieve real-time monitoring of the AIS base station load status and the selection of the optimal base station, the current base station load status is first generated through dynamic analysis of the base station's own VHF time slot occupancy rate and message sending task queue. The base station load status is generated based on real-time collected operating parameters, such as the current time slot occupancy ratio, the number of queued messages, and the time taken to process messages. These parameters reflect the current operating capacity and communication load status of the base station. The delivery equipment can identify whether the base station is close to or has reached a preset percentage of its rated working capacity.

[0102] When selecting the optimal base station, the ship's motion data and short message routing table are further combined to ensure that the message can be transmitted through the optimal path. The list of base stations that need to be transmitted is calculated based on the speed and heading in the motion data and the short message routing table. The calculation process is:

[0103]

[0104] Wherein, d(i) is a record of the short message routing table that meets the conditions, sog is the speed information in the position report, cog is the ground route information in the position report, and msgType is the message type;

[0105] When the base station operating load approaches a preset percentage of its rated capacity, the delivery device will prioritize the next available base station in the direction of the ship's travel. To accurately determine this base station, the system further classifies the ship's speed.

[0106] When it is determined that the speed sog is less than Vset, the calculation expression of the next available base station is as follows:

[0107]

[0108] Wherein, f2(mmsi,msgType) is the base station expected to be delivered obtained through mmsi and message type, d(j) is a record of the short message routing table that meets the conditions, and Vset is the speed preset value based on the performance of the base station;

[0109] When the speed sog ≥ Vset, the calculation expression of the next available base station is as follows:

[0110]

[0111] In addition, in order to further improve the reliability of base station selection, the delivery device also implements the function of base station time slot reservation. Before the message is delivered, the time slot reservation is made through the base station. If the reservation fails, the message is still sent based on the next base station in the direction of the ship's movement. The calculation expression is as follows:

[0112]

[0113] Among them, Sload is the base station load, Reservation is the reservation result, 1 is success, 0 is failure, and the selection is made according to the direction of the ship's movement. d(k+1) indicates the selection of the next nearby node according to the direction of the ship's movement. By real-time monitoring of the base station load status and combining the best transmission link, not only can the base station resources be fully utilized and the communication efficiency be improved, but it can also adapt to the dynamically changing ship movement status and communication environment, effectively improving the reliability and stability of AIS message transmission.

[0114] See also Figure 3 A second aspect of the present invention provides an AIS message delivery device under a high-density base station cluster, comprising:

[0115] A motion trajectory prediction unit is used to obtain an AIS message received by an AIS base station within its coverage area, parse the AIS message to generate motion data of the ship, and predict the motion trajectory of the ship within a preset time period in the future based on the motion data of the ship;

[0116] A communication quality evaluation unit, used to evaluate the communication quality between the ship and the base station based on the sending and receiving time of the AIS message, the sending and receiving confirmation time of the binary short message and the number of retransmissions;

[0117] An optimal transmission link determination unit, configured to generate an optimal transmission link for the ship within a preset time period in the future according to a movement trajectory of the ship within a preset time period in the future and a communication quality between the ship and a base station;

[0118] The dynamic adjustment unit is used to monitor the VHF time slot occupancy rate and message sending task queue of the AIS base station itself in real time, generate the current base station load status, and select the optimal base station for signal transmission based on the optimal sending link and the base station load status.

[0119] A third aspect of the present invention provides an AIS message delivery device in a high-density base station cluster, comprising a memory and a processor, wherein the memory stores a computer program, and the computer program can be executed by the processor to implement an AIS message delivery method in a high-density base station cluster as described in any one of the above items.

[0120] A fourth aspect of the present invention provides a computer-readable storage medium, characterized in that a computer program is stored therein, and the computer program can be executed by a processor of a device where the computer-readable storage medium is located to implement an AIS message delivery method under a high-density base station cluster as described in any one of the above items.

[0121] Based on the AIS message delivery method, device, equipment and storage medium under a high-density base station cluster provided by the present invention, the AIS message received by the AIS base station within its coverage is first obtained, the AIS message is parsed to generate the motion data of the ship, and the motion trajectory of the ship within a preset time period in the future is predicted based on the motion data of the ship; then, the communication quality between the ship and the base station is evaluated and generated based on the sending and receiving time of the AIS message, the sending and receiving confirmation time of the binary short message and the number of retransmissions; then, the best sending link for the ship within the preset time period in the future is generated based on the motion trajectory of the ship within the preset time period in the future and the communication quality between the ship and the base station; finally, the VHF time slot occupancy rate and the message sending task queue of the AIS base station itself are monitored in real time to generate the current base station load state, and the optimal base station is selected for signal transmission based on the best sending link and the base station load state, thereby reducing the air signal load occupied by sending messages.

[0122] Exemplarily, the computer program described in the third embodiment and the fourth embodiment of the present invention can be divided into one or more modules, and the one or more modules are stored in the memory and executed by the processor to complete the present invention. The one or more modules can be a series of computer program instruction segments that can complete specific functions, and the instruction segments are used to describe the execution process of the computer program in the AIS message delivery device under the implementation of a high-density base station cluster. For example, the device described in the second embodiment of the present invention.

[0123] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc. The processor is the control center of the AIS message delivery method under a high-density base station cluster, and uses various interfaces and lines to connect the various parts of the entire AIS message delivery method under a high-density base station cluster.

[0124] The memory can be used to store the computer program and / or module, and the processor realizes various functions of an AIS message delivery method under a high-density base station cluster by running or executing the computer program and / or module stored in the memory, and calling the data stored in the memory. The memory can mainly include a program storage area and a data storage area, wherein the program storage area can store an operating system, an application required for at least one function (such as a sound playback function, a text conversion function, etc.), etc.; the data storage area can store data created according to the use of the mobile phone (such as audio data, text message data, etc.), etc. In addition, the memory can include a high-speed random access memory, and can also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart memory card (SmartMediaCard, SMC), a secure digital (SecureDigital, SD) card, a flash card (FlashCard), at least one disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0125] Wherein, if the implemented module is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Wherein, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium. It should be noted that the content contained in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electric carrier signals and telecommunication signals.

[0126] It should be noted that the device embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. In addition, in the accompanying drawings of the device embodiments provided by the present invention, the connection relationship between the modules indicates that there is a communication connection between them, which may be specifically implemented as one or more communication buses or signal lines. A person of ordinary skill in the art may understand and implement it without paying any creative effort.

[0127] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for delivering AIS messages in a high-density base station cluster, characterized in that: include: Acquire an AIS message received by an AIS base station within its coverage area, parse the AIS message to generate ship motion data, and predict the movement trajectory of the ship within a preset time period in the future based on the ship motion data; The communication quality between the ship and the base station is evaluated and generated based on the sending and receiving time of the AIS message, the sending and receiving confirmation time of the binary short message and the number of retransmissions; Generate an optimal transmission link for the ship within a preset time period in the future according to the movement trajectory of the ship within a preset time period in the future and the communication quality between the ship and the base station; The VHF time slot occupancy rate and message sending task queue of the AIS base station itself are monitored in real time to generate the current base station load status, and the optimal base station is selected for signal transmission based on the optimal sending link and the base station load status.

2. The AIS message delivery method under a high-density base station cluster according to claim 1, characterized in that: The AIS message received by the AIS base station within its coverage is obtained, the AIS message is parsed to generate the motion data of the ship, and the motion trajectory of the ship within a preset time period in the future is predicted according to the motion data of the ship, specifically: After receiving the AIS message, the AIS message is parsed and filtered according to the AIS message protocol to generate filtered motion data; Calculate the motion trajectory within a preset time period in the future according to the filtered motion data. Specifically, calculate the motion trend of the ship in the future according to the motion trends at three time points in the history of the ship, wherein the motion trend includes the motion acceleration alon and the motion acceleration alat; Prediction at t feature The calculation formula of time is as follows: Among them, lon history3 is the longitude value at the time of history3, lat history3 is the latitude value at the time of history3, vlon history3 is the speed value in the longitude direction at the time of history3, vlat history3 is the velocity value in the latitude direction at the time of history3, t feature is the time of feature moment, t history3 is the time of history3, alon is the acceleration in the longitude direction, alat is the acceleration in the latitude direction, lon featrue The longitude value at the feature time, lat featrue The latitude value at the feature time.

3. The AIS message delivery method under a high-density base station cluster according to claim 2, characterized in that: The filtering includes: When a trajectory reversal point appears, determine whether the next point moves in the reversal direction, if not, remove the current point; When a speed-increasing point appears, the motion acceleration is calculated, and when the motion acceleration exceeds a threshold value set according to the ship type, the point is eliminated; Among them, Δlat is the change in latitude, Δlon is the change in longitude, R is the average radius of the earth, arcsin represents the inverse sine function, Δs is the moving distance, a is the acceleration, and Δt is the time difference between two points.

4. The AIS message delivery method under a high-density base station cluster according to claim 1, characterized in that: The communication quality between the ship and the base station is evaluated and generated based on the sending and receiving time of the AIS message, the sending and receiving confirmation time of the binary short message and the number of retransmissions, specifically: Extract the ship position report in the AIS message, save the area where the ship is located and the source AIS base station information, parse the UTC second data in the ship position report and the UTC second data when the position report is received, and record the communication delay; Record the time when the ship sends the binary short message, the time when the ship receives the binary confirmation message in response, and the number of times the binary short message is resent, and generate statistics on the message trigger success rate; A communication quality is generated based on the communication delay and the message touch-off success rate.

5. The AIS message delivery method under a high-density base station cluster according to claim 4, characterized in that: The step of generating the best transmission link for the ship within a preset time period in the future according to the movement trajectory of the ship within a preset time period in the future and the communication quality between the ship and the base station is specifically: The ship communication quality score under the base station is calculated according to the communication delay and the message touch success rate, and its expression is: Where, mmsi is the user ID value in the location report, UTCreceive is the UTC second of the received location report, UTCsend is the UTC second in the location report data, frquencyOfReception is the number of received location reports, Tsend is the binary short message sending time, Treply is the time when the binary confirmation reply is received, RetryTimes is the sum of the historical retries of sending short messages, times is the number of historical short message sending times, α, β, γ are data weight values ​​used to adjust the impact of sample size differences on unbalanced samples; A short message routing table of the ship is generated according to the communication quality score and the historical position information of the ship. According to the priority records in the short message routing table and in combination with the communication needs of a preset time in the future, the best sending link is dynamically adjusted and determined.

6. The AIS message delivery method in a high-density base station cluster according to claim 5, characterized in that: The selecting the optimal base station for signal transmission based on the optimal transmission link and the base station load state is specifically: Based on the speed and heading in the motion data and the short message routing table, a list of base stations that need to be transmitted is calculated, and the calculation process is: Wherein, d(i) is a record of the short message routing table that meets the conditions, sog is the speed information in the position report, cog is the ground route information in the position report, and msgType is the message type; According to the base station status information, and when it is detected that the operating load of the base station reaches a preset percentage of its rated working capacity, the next available base station located in the direction of the ship's travel is selected from the base station list to continue the message transmission task.

7. The AIS message delivery method in a high-density base station cluster according to claim 6, characterized in that: The step of selecting the next available base station located in the direction of the ship's travel from the base station list to continue the message transmission task is specifically as follows: When it is determined that the speed sog is less than Vset, the calculation expression of the next available base station is as follows: Wherein, f2(mmsi,msgType) is the base station expected to be delivered obtained through mmsi and message type, d(j) is a record of the short message routing table that meets the conditions, and Vset is the speed preset value based on the performance of the base station; When the speed sog ≥ Vset, the calculation expression of the next available base station is as follows: The time slot is reserved through the base station. If the reservation fails, the message is still sent according to the next base station in the direction of the ship's movement. The calculation expression is as follows: Among them, Sload is the base station load, Reservation is the reservation result, 1 is success, 0 is failure, and the selection is made according to the direction of movement of the ship. d(k+1) indicates that the next adjacent node is selected according to the direction of movement of the ship.

8. An AIS message delivery device under a high-density base station cluster, characterized in that: include: A motion trajectory prediction unit is used to obtain an AIS message received by an AIS base station within its coverage area, parse the AIS message to generate motion data of the ship, and predict the motion trajectory of the ship within a preset time period in the future based on the motion data of the ship; A communication quality evaluation unit, used to evaluate the communication quality between the ship and the base station based on the sending and receiving time of the AIS message, the sending and receiving confirmation time of the binary short message and the number of retransmissions; An optimal transmission link determination unit, configured to generate an optimal transmission link for the ship within a preset time period in the future according to a movement trajectory of the ship within a preset time period in the future and a communication quality between the ship and a base station; The dynamic adjustment unit is used to monitor the VHF time slot occupancy rate and message sending task queue of the AIS base station itself in real time.

9. An AIS message delivery device under a high-density base station cluster, characterized in that: It comprises a memory and a processor, wherein the memory stores a computer program, and the computer program can be executed by the processor to implement an AIS message delivery method under a high-density base station cluster as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: A computer program is stored, and the computer program can be executed by a processor of the device where the computer-readable storage medium is located to implement an AIS message delivery method under a high-density base station cluster as described in any one of claims 1 to 7.

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