A method and system for enhancing the continuity of VDES satellite multi-antenna communication based on TDMA scheduling

Abstract

This invention provides a method and system for enhancing the continuity of VDES satellite multi-antenna communication based on TDMA scheduling, comprising: configuring multiple Yagi antennas on the VDES satellite payload so that the coverage areas of each antenna form continuous or quasi-continuous coverage ranges along the satellite's flight trajectory, with coverage gaps existing between adjacent coverage areas; parsing ship position information through AIS data, calculating the satellite's coverage time series for a designated ship based on the satellite's trajectory, and identifying the antenna coverage scenario type the ship will experience; generating a candidate allocation scheme list based on the antenna coverage scenario identification results, and recording the number of TDMA frames that cannot be allocated for communication due to antenna coverage limitations; and allocating specific DC channels and time slot resources to the ship according to communication priority based on the candidate allocation scheme list for the ship to communicate with, under limited channel resources, ensuring that no data transmission occurs during antenna switching and gap periods, thereby achieving continuity of the communication session during multi-antenna switching and gap crossing processes.

Description

Technical Field

[0001] This invention relates to the field of maritime communication technology, and more particularly to a method and system for enhancing the continuity of VDES satellite multi-antenna communication based on TDMA scheduling. Background Technology

[0002] VDES (VHF Data Exchange System) is a next-generation maritime communication system following AIS (Automatic Identification System), primarily designed to address the spectrum congestion and insufficient communication capacity issues of AIS. The VDES satellite payload, as a core component of this system, enables wide-area coverage and data transmission for vessels at sea via satellite.

[0003] According to the ITU-R M.2092 international standard, VDES adopts TDMA (Time Division Multiple Access) communication, dividing each minute into 2250 time slots, which are further divided into 3 TDMA frames. Each frame contains multiple logical channels. Among them, 6 logical channels are DC (data channels), and each communication requires selecting one DC channel, occupying 30 to 90 time slots. This communication mechanism provides efficient data exchange capabilities for ships at sea, but it also brings new technical challenges.

[0004] However, existing VDES satellite payloads suffer from significant technical limitations in practical applications. First, due to the satellite's high-speed motion (approximately 8 km / s) and limited antenna coverage, the continuous communication time between a single antenna and the ship is extremely short, making it difficult to support long-duration data transmission requirements. Second, while using multiple antennas can extend service duration, the communication time between each antenna and the same ship remains relatively short, resulting in only multiple discontinuous transmissions of small data volumes. Furthermore, in TDMA communication systems, each transmission session establishment requires resource allocation and channel protection operations; frequent session establishment wastes TDMA channel resources and reduces overall communication efficiency. These problems severely restrict the performance of VDES satellite payloads, necessitating a technical solution that optimizes resource utilization, extends service duration, and ensures communication continuity. Summary of the Invention

[0005] To address the aforementioned technical problems of limited service duration, discontinuous coverage, and low resource utilization of existing VDES satellite payloads, this invention provides a method and system for enhancing the continuity of VDES satellite multi-antenna communication based on TDMA scheduling. This invention primarily utilizes multiple Yagi antennas configured on the VDES satellite payload to form quasi-continuous coverage. Through coverage scene identification, logical channel allocation, and dynamic scheduling, antenna coverage gaps and antenna switching times are allocated to the non-communication periods of TDMA frames. This effectively increases the service duration of the VDES satellite payload for a single vessel, ensures the continuity of communication sessions during multi-antenna switching and gap crossing processes, and improves the utilization rate of TDMA channel resources.

[0006] The technical means employed in this invention are as follows:

[0007] A method for enhancing the continuity of VDES satellite multi-antenna communication based on TDMA scheduling includes: S1. Multiple Yagi antennas are configured on the VDES satellite payload so that the coverage area of ​​each antenna forms a continuous or quasi-continuous coverage area on the satellite flight trajectory, with coverage gaps between adjacent coverage areas; S2. Analyze the ship's position information through the AIS data reported by the ship, and calculate the satellite coverage time series for the specified ship based on the satellite's orbital trajectory to identify the type of antenna coverage scenario that the ship will experience; S3. Based on the identification results of the antenna coverage scene, count all available logical channels, communication time and the combination of occupied antennas of the ship, generate a candidate allocation scheme list, and record the number of TDMA frames that cannot be allocated for communication due to antenna coverage. S4. Based on the list of candidate allocation schemes for all ships to be communicated, allocate specific DC channels and time slots to the ships according to communication priority under limited channel resources, ensuring that no data transmission occurs during antenna switching and blank periods, and achieving continuity of communication sessions during multi-antenna switching and blank period crossing. S5. Execute antenna switching logic at the coverage time boundary to ensure that the communication task corresponding to the switched antenna has been completed or paused, and the communication task of the new coverage antenna starts to be executed after the switching is completed, so as to achieve smooth switching between multiple antennas.

[0008] Further, step S1 includes: S11. Multiple Yagi antennas are arranged on the VDES satellite payload, including at least six tangential antennas distributed circumferentially along the satellite's flight direction and at least one nadir antenna, wherein the tangential antennas point in the direction of the Earth's tangency and the nadir antennas point in the nadir point. S12. Configure independent signal transceiver circuits and baseband processing units corresponding to each antenna to process the transmit and receive signals of each antenna respectively. S13. Each tangential antenna in the tangential antenna group has a different preset angle with the satellite's direction of travel. The coverage area of ​​each tangential antenna is the projection of a cone-shaped coverage area centered on the pointing direction onto the ground. The coverage areas of each tangential antenna are distributed circumferentially around the nadir point and together form the outer coverage area. S14. The coverage area of ​​the under-satellite antenna is located around the under-satellite point, and there is a circular coverage blank area between the outer coverage area and the coverage area around the under-satellite point; S15. The overall coverage area of ​​all antennas on the ground is combined to form a circular coverage area. The circular coverage area is quasi-continuous coverage, and the annular coverage blank area is located inside the circular coverage area. S16. Each tangential antenna in the tangential antenna group is defined as antenna A, antenna B, antenna C, antenna D, antenna E, and antenna F in a counterclockwise order around the nadir point according to its coverage area. The nadir antenna is defined as antenna G.

[0009] Further, step S2 includes: S21. Receive AIS data reported by the ship, parse the AIS data, and obtain the ship's real-time location information; S22. Determine the satellite's orbital trajectory based on the satellite's orbital parameters, combine it with the ship's real-time position information, calculate the relative positional relationship between the satellite and the ship, and then determine the start and end times of the satellite's coverage of the designated ship, generating a coverage time series. S23. Based on the coverage time series, identify the types of coverage scenarios the ship will experience, including a first scenario, a second scenario, a third scenario, and a fourth scenario, wherein: The first scenario is single-antenna B coverage, with a coverage time of ; The second scenario involves switching coverage from antenna A to antenna B and then back to antenna C, which has a time boundary. ,in For antenna A coverage, For antenna B coverage, For antenna C coverage; The third scenario involves a switch from coverage by antenna A through a blank area to coverage by antenna C, which has a time boundary. ,in For antenna A coverage, This is a blank area without antenna coverage. For antenna C coverage; The fourth scenario involves switching from antenna A coverage through a first blank area to antenna G coverage, then switching again through a second blank area to antenna C coverage, which has a time boundary. ,in For antenna A coverage, This is the first blank area without antenna coverage. For antenna G coverage, This is the second blank area without antenna coverage. For antenna C coverage.

[0010] Further, step S3 includes: S31. Based on the coverage scene identification results, determine the coverage status of the ship in each time period and distinguish between available communication periods and unavailable communication periods; S32. Traverse all possible allocation methods for the ship: Enumerate the available DC channels, available time slot locations, and available antennas within the available communication time period to form a list of candidate allocation schemes for the ship. S33. Record the number of TDMA frames that could not be allocated for communication due to the ship being in an unavailable communication period. This number is the number of sacrificed frames for this communication session.

[0011] Further, in step S32, the candidate allocation scheme includes: For the third scenario, the candidate allocation method includes time period. The set of schemes using antenna A and any one of channels DC0-DC5 within a given time period, and the time period within a given time period. The set of schemes that use antenna C and any one of the channels DC0-DC5; For the fourth scenario, candidate allocation methods also include time periods. The set of schemes that use antenna G within the area, and alternative schemes in which communication is abandoned in both the first and second blank areas.

[0012] Further, step S4 includes: S41. Receive a list of candidate allocation schemes for all ships to be scheduled; S42. Calculate the dispatch priority according to the urgency of communication and service quality requirements of each vessel: emergency safety data has the highest priority, followed by real-time monitoring data, and finally general communication data; when priorities are the same, dispatching shall be carried out according to the first-come, first-served principle. S43. Select the highest priority ship from all ships to be scheduled, and select the scheme from the candidate allocation schemes of the ship that matches the currently available channel resources and does not conflict with other scheduled ships. S44. If a conflict exists, try other candidate solutions for the vessel. If all candidate solutions conflict, mark the vessel as unavailable for service in this scheduling cycle. S45. Repeat steps S43 to S44 until all ships have been processed or no channel resources are available.

[0013] Furthermore, step S4 also includes a dynamic adjustment mechanism, as detailed below: S47. After each TDMA frame ends, update the channel resource status based on the actual channel usage and ship feedback information; S48. For ships that fail to communicate, priority shall be given to reallocating channels for them in the next scheduling cycle. S49. For vessels with newly added communication needs, add them to the dispatch queue in real time.

[0014] Further, step S5 includes: S51. Trigger an antenna switching command at the coverage time boundary, control the signal transceiver circuit of the switched antenna to complete the transmission or reception of the current data frame and then enter a pause state, while activating the signal transceiver circuit of the new coverage antenna. S52. After the new coverage antenna is activated, the communication session context of the original antenna is migrated to the new antenna, so that the communication session remains active during the handover process, and only data transmission is paused. S53. After the handover is completed, the new coverage antenna continues to perform the unfinished communication task or starts a new communication task.

[0015] This invention also provides a VDES satellite multi-antenna communication continuity enhancement system based on TDMA scheduling, implemented using the aforementioned TDMA-based scheduling method. The system includes: an antenna configuration module, a coverage scene identification module, a logical channel allocation module, a dynamic scheduling module, and an antenna handover execution module, wherein: The antenna configuration module is used to configure multiple Yagi antennas on the VDES satellite payload, so that the coverage area of ​​each antenna forms a continuous or quasi-continuous coverage range on the satellite flight trajectory, and there are coverage gaps between adjacent coverage areas. The coverage scene identification module is used to parse the ship's location information through the AIS data reported by the ship, and calculate the satellite coverage time series of the specified ship based on the satellite's orbital trajectory to identify the type of antenna coverage scene that the ship will experience. The logical channel allocation module is used to count all available logical channels, communication times and combinations of occupied antennas on the ship according to the identification results of the antenna coverage scene, generate a list of candidate allocation schemes, and record the number of TDMA frames that cannot be allocated for communication due to antenna coverage. The dynamic scheduling module is used to allocate specific DC channels and time slots to ships according to communication priorities under limited channel resources, based on a list of candidate allocation schemes for all ships to be communicated with, to ensure that no data transmission occurs during antenna switching and blank periods, thereby achieving continuity of the communication session during multi-antenna switching and blank period crossing. The antenna switching execution module is used to execute antenna switching logic at the coverage time boundary, so that the communication task corresponding to the switched antenna has been completed or paused, and the communication task of the new coverage antenna starts to be executed after the switching is completed, thereby realizing smooth switching between multiple antennas.

[0016] Compared with the prior art, the present invention has the following advantages: 1. The multi-antenna configuration scheme provided by this invention, through intelligent adaptation to the TDMA frame structure, significantly improves the service duration of a single ship via satellite. Specifically, by using multiple Yagi antennas at the front, middle, and rear to form quasi-continuous coverage, the communication session duration between the ship and the satellite is extended from approximately 60 seconds with a single antenna to approximately 118 seconds, resulting in an effective service duration increase of approximately 96.7%.

[0017] 2. The coverage scene identification and logical channel allocation mechanism provided by this invention, through coordinated operation with the dynamic scheduling algorithm, ensures the continuity of communication sessions during multi-antenna handover and blank zone traversal. By planning blank zone moments and antenna handover moments as session hold-up states where no data transmission occurs, the communication session remains active, only data transmission is paused, and the user is unaware of any communication interruption.

[0018] 3. The heuristic dynamic scheduling method provided by this invention, combined with a multi-priority queue management strategy, achieves a significant improvement in TDMA channel resource utilization while ensuring scheduling fairness. While prioritizing the transmission of urgent and secure data, it maximizes the number of ships served under limited channel resources through candidate allocation scheme enumeration and conflict resolution mechanisms, avoiding resource waste caused by multiple session establishments.

[0019] In summary, by applying the technical solution of this invention, the problems of short single-antenna coverage time and insufficient service duration caused by high-speed satellite movement, discontinuous coverage due to multi-antenna switching, and wasted TDMA channel resources caused by multiple session establishments in the prior art are addressed. Through the deep integration of a multi-antenna quasi-continuous coverage architecture and a TDMA intelligent scheduling algorithm, antenna coverage gaps and switching times are allocated to non-communication periods. This extends service duration while maintaining session continuity and optimizing resource utilization. Therefore, the technical solution of this invention can increase the service duration of a single ship by 140% for VDES satellite payloads, effectively solving the problems of limited service duration, discontinuous coverage, and low resource utilization in the prior art.

[0020] Based on the above reasons, this invention can be widely applied in fields such as maritime satellite communication, VDES system upgrades, intelligent maritime supervision, and ocean-going vessel data services. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a flowchart of the method of the present invention.

[0023] Figure 2 This is a schematic diagram of the antenna coverage area of ​​the present invention.

[0024] Figure 3 This is the VDE-SAT logical channel allocation diagram of the present invention. Detailed Implementation

[0025] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0026] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0027] This invention provides a method for enhancing the continuity of VDES satellite multi-antenna communication based on TDMA scheduling, comprising: S1. Multiple Yagi antennas are configured on the VDES satellite payload so that the coverage area of ​​each antenna forms a continuous or quasi-continuous coverage area on the satellite flight trajectory, with coverage gaps between adjacent coverage areas; S2. Analyze the ship's position information through the AIS data reported by the ship, and calculate the satellite coverage time series for the specified ship based on the satellite's orbital trajectory to identify the type of antenna coverage scenario that the ship will experience; S3. Based on the identification results of the antenna coverage scene, count all available logical channels, communication time and the combination of occupied antennas of the ship, generate a candidate allocation scheme list, and record the number of TDMA frames that cannot be allocated for communication due to antenna coverage. S4. Based on the list of candidate allocation schemes for all ships to be communicated, allocate specific DC channels and time slots to the ships according to communication priority under limited channel resources, ensuring that no data transmission occurs during antenna switching and blank periods, and achieving continuity of communication sessions during multi-antenna switching and blank period crossing. S5. Execute antenna switching logic at the coverage time boundary to ensure that the communication task corresponding to the switched antenna has been completed or paused, and the communication task of the new coverage antenna starts to be executed after the switching is completed, so as to achieve smooth switching between multiple antennas.

[0028] In this embodiment, as Figure 1 As shown, the system includes an antenna section, a signal processing section, and a protocol processing section. The protocol processing section further comprises a coverage scene identification section, a logical channel allocation section, and a dynamic scheduling section. Specifically, the protocol processing section loads the VDE-SAT link layer processing protocol, uses intelligent algorithms for logical channel allocation, and maintains the VDE transmission protocol between the payload and the ship's docking station. The protocol processing section allocates logical channels through intelligent algorithms, increasing satellite coverage duration by allocating coverage gaps and antenna switching times to every minute of non-communication time. The intelligent algorithm includes the coverage scene identification section, the logical channel allocation section, and the dynamic scheduling section.

[0029] In a specific implementation, as a preferred embodiment of the present invention, step S1 includes: S11. Multiple Yagi antennas are arranged on the VDES satellite payload, including at least six tangential antennas distributed circumferentially along the satellite's flight direction and at least one nadir antenna, wherein the tangential antennas point in the direction of the Earth's tangency and the nadir antennas point in the nadir point. S12. Configure independent signal transceiver circuits and baseband processing units corresponding to each antenna to process the transmit and receive signals of each antenna respectively. S13. Each tangential antenna in the tangential antenna group has a different preset angle with the satellite's direction of travel. The coverage area of ​​each tangential antenna is the projection of a cone-shaped coverage area centered on the pointing direction onto the ground. The coverage areas of each tangential antenna are distributed circumferentially around the nadir point and together form the outer coverage area. In this embodiment, a total of 7 Yagi antennas are used, with 6 antennas pointing towards the tangent direction of the Earth and angles of 30 degrees, 90 degrees, 150 degrees, 210 degrees, 270 degrees, and 330 degrees with the satellite's direction of travel, respectively. The 7th antenna points towards the nadir point. The coverage area of ​​each antenna is the projection of a cone-shaped area 60 degrees away from the pointing direction onto the Earth. S14. The coverage area of ​​the under-satellite antenna is located around the under-satellite point, and there is a circular coverage blank area between the outer coverage area and the coverage area around the under-satellite point; S15. The coverage areas of all antennas on the ground are combined to form a circular coverage area, which is a quasi-continuous coverage area. The annular coverage gap is located inside the circular coverage area. In this embodiment, the coverage area of ​​all antennas on the ground is a circular area with a diameter of 5000km, wherein there is an annular coverage gap with a radius of 300km to 400km between adjacent antenna coverage areas. S16, as Figure 2 As shown, the tangential antennas in the tangential antenna group are defined as antenna A, antenna B, antenna C, antenna D, antenna E, and antenna F respectively, according to the order in which their coverage areas are arranged counterclockwise around the sub-satellite point. The sub-satellite antenna is defined as antenna G.

[0030] In a specific implementation, as a preferred embodiment of the present invention, step S2 includes: S21. Receive AIS data reported by the ship, parse the AIS data, and obtain the ship's real-time location information; S22. Determine the satellite's orbital trajectory based on the satellite's orbital parameters, combine it with the ship's real-time position information, calculate the relative positional relationship between the satellite and the ship, and then determine the start and end times of the satellite's coverage of the designated ship, generating a coverage time series. S23. Based on the coverage time series, identify the types of coverage scenarios the ship will experience, including a first scenario, a second scenario, a third scenario, and a fourth scenario, wherein: The first scenario is single-antenna B coverage, with a coverage time of ; The second scenario involves switching coverage from antenna A to antenna B and then back to antenna C, which has a time boundary. ,in For antenna A coverage, For antenna B coverage, For antenna C coverage; The third scenario involves a switch from coverage by antenna A through a blank area to coverage by antenna C, which has a time boundary. ,in For antenna A coverage, This is a blank area without antenna coverage. For antenna C coverage; The fourth scenario involves switching from antenna A coverage through a first blank area to antenna G coverage, then switching again through a second blank area to antenna C coverage, which has a time boundary. ,in For antenna A coverage, This is the first blank area without antenna coverage. For antenna G coverage, This is the second blank area without antenna coverage. For antenna C coverage.

[0031] In this embodiment, there are eight possible scenarios for the satellite's antenna covering the ship during flight: single antenna B coverage; switching from antenna A coverage to antenna B coverage and then to antenna C coverage; switching from antenna A coverage through a blank area to antenna C coverage; switching from antenna A coverage through a first blank area to antenna G coverage and then through a second blank area to antenna C coverage; switching from antenna F coverage through a first blank area to antenna G coverage and then through a second blank area to antenna C coverage; switching from antenna F coverage through a blank area to antenna D coverage; switching from antenna F coverage to antenna E coverage and then back to antenna D coverage; and single antenna E coverage.

[0032] Since the system has a symmetrical structure, the first four cases are the same as the last four cases, and we will mainly analyze the first four cases; the case of single antenna B coverage is the same as the conventional single antenna logic and does not require special processing.

[0033] For the three scenarios of switching coverage from antenna A to antenna B and then to antenna C, switching coverage from antenna A through a gap to antenna C, and switching coverage from antenna A through the first gap to antenna G and then to antenna C through the second gap, the antenna coverage time is calculated in advance as follows: , , .

[0034] In a specific implementation, as a preferred embodiment of the present invention, step S3 includes: S31. Based on the coverage scene identification results, determine the coverage status of the ship in each time period and distinguish between available communication periods and unavailable communication periods; S32. Traverse all possible allocation methods for the ship: Enumerate the available DC channels, available time slot locations, and available antennas within the available communication time period to form a list of candidate allocation schemes for the ship. S33. Record the number of TDMA frames that could not be allocated for communication due to the ship being in an unavailable communication period. This number is the number of sacrificed frames for this communication session. In this embodiment, specifically, 2250 time slots per minute are divided into 3 TDMA frames, each frame has 720 time slots, and each frame lasts approximately 20 seconds. Each frame contains 6 DC (Data Channel) channels (numbered DC0 to DC5), and each DC channel occupies 30-90 time slots for each communication, lasting approximately 0.8-2.4 seconds. Each frame also contains a DSCH (Data Signalling Channel) acknowledgment channel, with a total of 30 time slots used for acknowledgment feedback.

[0035] In a specific implementation, as a preferred embodiment of the present invention, step S32 includes the following candidate allocation scheme: For the third scenario, the candidate allocation method includes time period. The set of schemes using antenna A and any one of channels DC0-DC5 within a given time period, and the time period within a given time period. The set of schemes that use antenna C and any one of the channels DC0-DC5; For the fourth scenario, candidate allocation methods also include time periods. The set of schemes that use antenna G within the area, and alternative schemes in which communication is abandoned in both the first and second blank areas.

[0036] In this embodiment, satellite VDE communication uses TDMA communication, with each minute divided into 2250 time slots; each minute is divided into 3 TDMA frames; each TDMA frame is divided into several logical channels; among them, 6 logical channels are DC channels, and one DC channel is selected for each communication. Each DC channel occupies 30-90 time slots, meaning that the satellite communicates with the ship VDE 3 times per minute, with each communication lasting 0.8-2.4 seconds. The logical channel division is as follows: Figure 3 As shown. In a specific implementation, as a preferred embodiment of the present invention, step S4 includes: S41. Receive a list of candidate allocation schemes for all ships to be scheduled; S42. Calculate the dispatch priority according to the urgency of communication and service quality requirements of each vessel: emergency safety data has the highest priority, followed by real-time monitoring data, and finally general communication data; when priorities are the same, dispatching shall be carried out according to the first-come, first-served principle. S43. Select the highest priority ship from all ships to be scheduled, and select the scheme from the candidate allocation schemes of the ship that matches the currently available channel resources and does not conflict with other scheduled ships. S44. If a conflict exists, try other candidate solutions for the vessel. If all candidate solutions conflict, mark the vessel as unavailable for service in this scheduling cycle. S45. Repeat steps S43 to S44 until all ships have been processed or no channel resources are available.

[0037] In a specific implementation, as a preferred embodiment of the present invention, step S4 further includes a dynamic adjustment mechanism, as follows: S47. After each TDMA frame ends, update the channel resource status based on the actual channel usage and ship feedback information; S48. For ships that fail to communicate, priority shall be given to reallocating channels for them in the next scheduling cycle. S49. For vessels with newly added communication needs, add them to the dispatch queue in real time.

[0038] In this embodiment, the dynamic scheduling unit, based on a list of candidate allocation schemes for all vessels seeking communication, optimizes scheduling to provide communication services to as many vessels as possible within limited channel resources. Regarding antenna switching, the dynamic scheduling unit ensures that at the point when antenna coverage changes, the communication task corresponding to the switched antenna has been completed or paused, and the communication task of the newly covered antenna begins execution after the switch is complete, thus achieving continuity of the communication session during antenna switching.

[0039] In a specific implementation, as a preferred embodiment of the present invention, step S5 includes: S51. Trigger an antenna switching command at the coverage time boundary, control the signal transceiver circuit of the switched antenna to complete the transmission or reception of the current data frame and then enter a pause state, while activating the signal transceiver circuit of the new coverage antenna. S52. After the new coverage antenna is activated, the communication session context of the original antenna is migrated to the new antenna, so that the communication session remains active during the handover process, and only data transmission is paused. S53. After the handover is completed, the new coverage antenna continues to perform the unfinished communication task or starts a new communication task.

[0040] The overall workflow is as follows: After the satellite enters the coverage area, the protocol processing part first parses the ship's position information using the AIS data reported by the ship; the coverage scene identification part calculates the satellite's coverage time series for the ship based on the ship's position and satellite trajectory, and identifies the type of coverage scene the ship will experience; for the first scene, single-antenna B coverage, standard TDMA scheduling is used; for the second scene, continuous three-antenna coverage, continuous antenna scheduling is used; for the third scene, single blank area coverage, single blank area skip scheduling is used; for the fourth scene, double blank area coverage, double blank area skip scheduling is used; the logical channel allocation part generates a list of candidate allocation schemes for each ship; the dynamic scheduling part allocates specific DC channels and time slot resources to the ship according to priority, ensuring that no data transmission occurs during antenna switching and blank area times; the antenna switching part executes antenna switching logic at the coverage time boundary to achieve smooth switching between multiple antennas.

[0041] This invention also provides a VDES satellite multi-antenna communication continuity enhancement system based on TDMA scheduling, implemented using the aforementioned TDMA-based scheduling method. The system includes: an antenna configuration module, a coverage scene identification module, a logical channel allocation module, a dynamic scheduling module, and an antenna handover execution module, wherein: The antenna configuration module is used to configure multiple Yagi antennas on the VDES satellite payload, so that the coverage area of ​​each antenna forms a continuous or quasi-continuous coverage range on the satellite flight trajectory, and there are coverage gaps between adjacent coverage areas. The coverage scene identification module is used to parse the ship's location information through the AIS data reported by the ship, and calculate the satellite coverage time series of the specified ship based on the satellite's orbital trajectory to identify the type of antenna coverage scene that the ship will experience. The logical channel allocation module is used to count all available logical channels, communication times and combinations of occupied antennas on the ship according to the identification results of the antenna coverage scene, generate a list of candidate allocation schemes, and record the number of TDMA frames that cannot be allocated for communication due to antenna coverage. The dynamic scheduling module is used to allocate specific DC channels and time slots to ships according to communication priorities under limited channel resources, based on a list of candidate allocation schemes for all ships to be communicated with, to ensure that no data transmission occurs during antenna switching and blank periods, thereby achieving continuity of the communication session during multi-antenna switching and blank period crossing. The antenna switching execution module is used to execute antenna switching logic at the coverage time boundary, so that the communication task corresponding to the switched antenna has been completed or paused, and the communication task of the new coverage antenna starts to be executed after the switching is completed, thereby realizing smooth switching between multiple antennas.

[0042] The embodiments of the present invention are described simply because they correspond to those in the embodiments above. For any similarities, please refer to the descriptions in the embodiments above, which will not be elaborated here.

[0043] Example 1: Communication Scheduling Method for Single Blank Area Coverage in the Third Scenario Assuming a typical scenario where a ship experiences a transition from antenna A coverage to a blank area and then back to antenna C coverage, the specific process is as follows: The covered time series is: Antenna A coverage, blank area Antenna C coverage; where Approximately 50 seconds, Approximately 20 seconds Approximately 50 seconds.

[0044] The time allocation for the three TDMA frames per minute is as follows: Frame 1 from 0 to 20 seconds, Frame 2 from 20 to 40 seconds, and Frame 3 from 40 to 60 seconds. Assume the current communication session is in the first frame... At this moment, the ship is covered by antenna A.

[0045] The candidate allocation schemes generated by the logical channel allocation section include: Within a given time period, a set of time slot allocation schemes using antenna A and any one of channels DC0-DC5; The set of time slot allocation schemes using antenna C and any one of the channels DC0-DC5 within the time period.

[0046] During scheduling, the dynamic scheduling component ensures that the communication time slot allocated to the vessel does not overlap with the network's communication schedule. Blank area. For example, if the communication of the first frame is in Starting at 5 seconds, the DC2 channel (60 time slots) can be allocated to the ship for downlink data transmission during the [5, 25] second time period of frame 1; during the [25, 45] second time period of frame 2, the ship is in a blank area and no channel is allocated; in frame 3... Starting at 45 seconds, the DC3 channel (50 time slots) is allocated to the vessel within a time period of [45, 60] seconds. This ensures that even if the vessel is unable to communicate in a no-communication zone, its communication session remains active, only data transmission is paused.

[0047] Compared to traditional solutions, this embodiment extends the communication session duration between the ship and the satellite from approximately 60 seconds (single antenna coverage time) to approximately 118 seconds (50 seconds of coverage from antenna A plus 50 seconds of coverage from antenna C, plus a 20-second session hold-up time in between), effectively increasing the service duration by approximately 96.7%.

[0048] Example 2: Fair Scheduling Method for Multiple Ships in Concurrent Scenarios Suppose that at a certain moment, five ships are simultaneously within the satellite coverage area, and each ship has different coverage scenarios and data transmission needs. The specific scheduling process is as follows: The first vessel is 10 seconds away from the boundary of the blank area, covering a single blank area, and has emergency safety alarm data to transmit, so it has the highest priority. The second vessel is 30 seconds away from the boundary of the blank area, covering three consecutive antennas, and has real-time monitoring data, so it has the next highest priority. The third, fourth, and fifth vessels each have general communication data, so they have lower priority.

[0049] The logical channel allocation section first generates a list of candidate allocation schemes for each ship: the scheme for the first ship includes a scheme to use any DC channel during the remaining coverage time before the blank area, and a scheme to resume communication after the blank area; the scheme for the second ship includes multiple schemes to use any DC channel during three consecutive antenna coverage periods; the schemes for the third, fourth, and fifth ships are similar.

[0050] The dynamic scheduling component schedules according to priority: first, the first vessel is allocated the last communication period before entering the blank area to ensure that emergency data is transmitted before entering the blank area; then, the second vessel is allocated a continuous antenna coverage period to ensure that its data can be transmitted across antennas; finally, the remaining channel resources are allocated to the third, fourth, and fifth vessels in a polling manner.

[0051] The scheduling results meet the following conditions: emergency data is transmitted before entering the blank area; communication is uninterrupted within the coverage of the second vessel's three consecutive antennas; and the third, fourth, and fifth vessels obtain fair channel allocation time.

[0052] 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 or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for enhancing the continuity of VDES satellite multi-antenna communication based on TDMA scheduling, characterized in that, include: S1. Multiple Yagi antennas are configured on the VDES satellite payload so that the coverage area of ​​each antenna forms a continuous or quasi-continuous coverage area on the satellite flight trajectory, with coverage gaps between adjacent coverage areas; S2. Analyze the ship's position information through the AIS data reported by the ship, and calculate the satellite coverage time series for the specified ship based on the satellite's orbital trajectory to identify the type of antenna coverage scenario that the ship will experience; S3. Based on the identification results of the antenna coverage scene, count all available logical channels, communication time and the combination of occupied antennas of the ship, generate a candidate allocation scheme list, and record the number of TDMA frames that cannot be allocated for communication due to antenna coverage. S4. Based on the list of candidate allocation schemes for all ships to be communicated, allocate specific DC channels and time slots to the ships according to communication priority under limited channel resources, ensuring that no data transmission occurs during antenna switching and blank periods, and achieving continuity of communication sessions during multi-antenna switching and blank period crossing. S5. Execute antenna switching logic at the coverage time boundary to ensure that the communication task corresponding to the switched antenna has been completed or paused, and the communication task of the new coverage antenna starts to be executed after the switching is completed, so as to achieve smooth switching between multiple antennas.

2. The method for enhancing the continuity of VDES satellite multi-antenna communication based on TDMA scheduling according to claim 1, characterized in that, Step S1 includes: S11. Multiple Yagi antennas are arranged on the VDES satellite payload, including at least six tangential antennas distributed circumferentially along the satellite's flight direction and at least one nadir antenna, wherein the tangential antennas point in the direction of the Earth's tangency and the nadir antennas point in the nadir point. S12. Configure independent signal transceiver circuits and baseband processing units corresponding to each antenna to process the transmit and receive signals of each antenna respectively. S13. Each tangential antenna in the tangential antenna group has a different preset angle with the satellite's direction of travel. The coverage area of ​​each tangential antenna is the projection of a cone-shaped coverage area centered on the pointing direction onto the ground. The coverage areas of each tangential antenna are distributed circumferentially around the nadir point and together form the outer coverage area. S14. The coverage area of ​​the under-satellite antenna is located around the under-satellite point, and there is a circular coverage blank area between the outer coverage area and the coverage area around the under-satellite point; S15. The overall coverage area of ​​all antennas on the ground is combined to form a circular coverage area. The circular coverage area is quasi-continuous coverage, and the annular coverage blank area is located inside the circular coverage area. S16. Each tangential antenna in the tangential antenna group is defined as antenna A, antenna B, antenna C, antenna D, antenna E, and antenna F in a counterclockwise order around the nadir point according to its coverage area. The nadir antenna is defined as antenna G.

3. The method for enhancing the continuity of VDES satellite multi-antenna communication based on TDMA scheduling according to claim 1, characterized in that, Step S2 includes: S21. Receive AIS data reported by the ship, parse the AIS data, and obtain the ship's real-time location information; S22. Determine the satellite's orbital trajectory based on the satellite's orbital parameters, combine it with the ship's real-time position information, calculate the relative positional relationship between the satellite and the ship, and then determine the start and end times of the satellite's coverage of the designated ship, generating a coverage time series. S23. Based on the coverage time series, identify the types of coverage scenarios the ship will experience, including a first scenario, a second scenario, a third scenario, and a fourth scenario, wherein: The first scenario is single-antenna B coverage, with a coverage time of ; The second scenario involves switching coverage from antenna A to antenna B and then back to antenna C, which has a time boundary. ,in For antenna A coverage, For antenna B coverage, For antenna C coverage; The third scenario involves a switch from coverage by antenna A through a blank area to coverage by antenna C, which has a time boundary. ,in For antenna A coverage, This is a blank area without antenna coverage. For antenna C coverage; The fourth scenario involves switching from antenna A coverage through a first blank area to antenna G coverage, then switching again through a second blank area to antenna C coverage, which has a time boundary. ,in For antenna A coverage, This is the first blank area without antenna coverage. For antenna G coverage, This is the second blank area without antenna coverage. For antenna C coverage.

4. The method for enhancing the continuity of VDES satellite multi-antenna communication based on TDMA scheduling according to claim 1, characterized in that, Step S3 includes: S31. Based on the coverage scene identification results, determine the coverage status of the ship in each time period and distinguish between available communication periods and unavailable communication periods; S32. Traverse all possible allocation methods for the ship: Enumerate the available DC channels, available time slot locations, and available antennas within the available communication time period to form a list of candidate allocation schemes for the ship. S33. Record the number of TDMA frames that could not be allocated for communication due to the ship being in an unavailable communication period. This number is the number of sacrificed frames for this communication session.

5. The method for enhancing the continuity of VDES satellite multi-antenna communication based on TDMA scheduling according to claim 4, characterized in that, In step S32, the candidate allocation scheme includes: For the third scenario, the candidate allocation method includes time period. The set of schemes using antenna A and any one of channels DC0-DC5 within a given time period, and the time period within a given time period. The set of schemes that use antenna C and any one of the channels DC0-DC5; For the fourth scenario, candidate allocation methods also include time periods. The set of schemes that use antenna G within the area, and alternative schemes in which communication is abandoned in both the first and second blank areas.

6. The method for enhancing the continuity of VDES satellite multi-antenna communication based on TDMA scheduling according to claim 1, characterized in that, Step S4 includes: S41. Receive a list of candidate allocation schemes for all ships to be scheduled; S42. Calculate the dispatch priority according to the urgency of communication and service quality requirements of each vessel: emergency safety data has the highest priority, followed by real-time monitoring data, and finally general communication data; when priorities are the same, dispatching shall be carried out according to the first-come, first-served principle. S43. Select the highest priority ship from all ships to be scheduled, and select the scheme from the candidate allocation schemes of the ship that matches the currently available channel resources and does not conflict with other scheduled ships. S44. If a conflict exists, try other candidate solutions for the vessel. If all candidate solutions conflict, mark the vessel as unavailable for service in this scheduling cycle. S45. Repeat steps S43 to S44 until all ships have been processed or no channel resources are available.

7. The method for enhancing the continuity of VDES satellite multi-antenna communication based on TDMA scheduling according to claim 6, characterized in that, Step S4 also includes a dynamic adjustment mechanism, as detailed below: S47. After each TDMA frame ends, update the channel resource status based on the actual channel usage and ship feedback information; S48. For ships that fail to communicate, priority shall be given to reallocating channels for them in the next scheduling cycle. S49. For vessels with newly added communication needs, add them to the dispatch queue in real time.

8. The method for enhancing the continuity of VDES satellite multi-antenna communication based on TDMA scheduling according to claim 1, characterized in that, Step S5 includes: S51. Trigger an antenna switching command at the coverage time boundary, control the signal transceiver circuit of the switched antenna to complete the transmission or reception of the current data frame and then enter a pause state, while activating the signal transceiver circuit of the new coverage antenna. S52. After the new coverage antenna is activated, the communication session context of the original antenna is migrated to the new antenna, so that the communication session remains active during the handover process, and only data transmission is paused. S53. After the handover is completed, the new coverage antenna continues to perform the unfinished communication task or starts a new communication task.

9. A VDES satellite multi-antenna communication continuity enhancement system based on TDMA scheduling, implemented according to the TDMA scheduling-based VDES satellite multi-antenna communication continuity enhancement method of any one of claims 1-8, characterized in that, include: The module includes an antenna configuration module, a coverage scene identification module, a logical channel allocation module, a dynamic scheduling module, and an antenna switching execution module, among which: The antenna configuration module is used to configure multiple Yagi antennas on the VDES satellite payload, so that the coverage area of ​​each antenna forms a continuous or quasi-continuous coverage range on the satellite flight trajectory, and there are coverage gaps between adjacent coverage areas. The coverage scene identification module is used to parse the ship's location information through the AIS data reported by the ship, and calculate the satellite coverage time series of the specified ship based on the satellite's orbital trajectory to identify the type of antenna coverage scene that the ship will experience. The logical channel allocation module is used to count all available logical channels, communication times and combinations of occupied antennas on the ship according to the identification results of the antenna coverage scene, generate a list of candidate allocation schemes, and record the number of TDMA frames that cannot be allocated for communication due to antenna coverage. The dynamic scheduling module is used to allocate specific DC channels and time slots to ships according to communication priorities under limited channel resources, based on a list of candidate allocation schemes for all ships to be communicated with, to ensure that no data transmission occurs during antenna switching and blank periods, thereby achieving continuity of the communication session during multi-antenna switching and blank period crossing. The antenna switching execution module is used to execute antenna switching logic at the coverage time boundary, so that the communication task corresponding to the switched antenna has been completed or paused, and the communication task of the new coverage antenna starts to be executed after the switching is completed, thereby realizing smooth switching between multiple antennas.

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