Downlink synchronization method, device, equipment, storage medium and computer program product

Abstract

Provided are a downlink synchronization method, apparatus, device, storage medium and computer program product, the downlink synchronization method comprising: determining a first time slot head position of a to-be-adjusted time slot corresponding to a first synchronization period and a feed link delay inequality corresponding to the first synchronization period, the to-be-adjusted time slot being a time slot obtained by speculation; adjusting the duration of the time slot to be adjusted according to the first time slot head position and the feed link delay inequality to obtain a target time slot; and performing downlink synchronization operation according to the target time slot. According to the scheme, by adjusting the time slot and reducing the synchronization error of the time slot, the on-satellite time synchronization accumulative error in one period is minimum, then the effective time of the wave control instruction is successfully adjusted, successful demodulation of all time slot symbols in the period is guaranteed, accurate downlink synchronization is achieved, and the time slot synchronization efficiency is improved. The problem that a downlink synchronization scheme cannot be accurately realized in a satellite communication scene in a transparent forwarding mode in the prior art is solved.

Description

Technical Field

[0001] This application relates to the field of communication technology, and in particular to a downlink synchronization method, apparatus, device, storage medium, and computer program product. Background Technology

[0002] To achieve transparent forwarding mode, most solutions utilize the downlink SSB (Synchronization Block) signal of the NR (New Radio) NTN (Non-Ground Network) transmitted via the feed link to control the satellite beam, enabling downlink synchronization between the terrestrial NTN base station and the satellite beam controller. However, due to the high-speed movement of the satellite, the transparent stream time slots arriving from the ground to the satellite change, resulting in the loss of some data within the time slots and demodulation failure, thus hindering accurate downlink synchronization.

[0003] As shown above, existing technologies for satellite communication scenarios in transparent forwarding mode suffer from problems such as the inability to accurately implement downlink synchronization schemes. Summary of the Invention

[0004] The purpose of this application is to provide a downlink synchronization method, apparatus, device, storage medium, and computer program product to solve the problem that the downlink synchronization scheme cannot be accurately implemented in satellite communication scenarios under transparent forwarding mode in the prior art.

[0005] To address the aforementioned technical problems, embodiments of this application provide a downlink synchronization method, including:

[0006] Determine the position of the first time slot header of the time slot to be adjusted corresponding to the first synchronization period and the power supply link delay difference corresponding to the first synchronization period, wherein the time slot to be adjusted is a predicted time slot;

[0007] Based on the position of the first time slot header and the delay difference of the power supply link, the duration of the time slot to be adjusted is adjusted to obtain the target time slot;

[0008] Downlink synchronization is performed based on the target time slot.

[0009] Optionally, determining the position of the first time slot header corresponding to the first synchronization period includes:

[0010] Based on at least one synchronization signal block (SSB) received within the first synchronization period, the second time slot header position of the time slot where the at least one SSB is located is obtained;

[0011] Based on the position of the second time slot head, the position of the first time slot head of the time slot to be adjusted is inferred.

[0012] Optionally, adjusting the duration of the time slot to be adjusted based on the position of the first time slot header and the delay difference of the power supply link to obtain the target time slot includes:

[0013] Based on the position of the first time slot head and the overhead status of the satellite equipment, the power supply link delay difference is evenly distributed to each of the time slots to be adjusted to obtain the target time slot;

[0014] The term "overhead" refers to the area above a ground gateway station during the movement of satellite equipment.

[0015] Optionally, the step of evenly distributing the feeder link delay difference to each of the time slots to be adjusted, based on the position of the first time slot head and the overhead status of the satellite equipment, to obtain the target time slot, includes:

[0016] The average value of the power supply link delay difference is obtained based on the number of the first timeslot header positions;

[0017] Based on the average value and the overhead position of the satellite equipment, the first time slot head position of each of the time slots to be adjusted is adjusted to obtain the target time slot.

[0018] Optionally, determining the power supply link delay difference corresponding to the first synchronization period includes:

[0019] If the overpass situation indicates that the satellite equipment does not pass overpass within the first synchronization period, the power supply link delay difference corresponding to the first synchronization period is determined based on the first reception time of the first SSB and the second reception time of the second SSB received within the first synchronization period.

[0020] The second SSB refers to the first SSB in the next synchronization period adjacent to the first synchronization period.

[0021] Optionally, the step of evenly distributing the feeder link delay difference to each of the time slots to be adjusted, based on the position of the first time slot head and the overhead status of the satellite equipment, to obtain the target time slot, includes:

[0022] If the overhead condition indicates that the satellite equipment will not be overhead during the first synchronization period, the power supply link delay difference is evenly distributed to each of the time slots to be adjusted according to the position of the first time slot head and the direction of movement of the satellite equipment relative to the ground gateway station, so as to obtain the target time slot.

[0023] Optionally, determining the power supply link delay difference corresponding to the first synchronization period includes:

[0024] When the overhead situation indicates that the satellite equipment is overhead within the first synchronization period, the first power supply link delay is obtained based on the first reception time of the first SSB received within the first synchronization period.

[0025] Based on the satellite equipment's overhead position information, determine the second feeder link delay corresponding to the satellite equipment's overhead position;

[0026] The third power supply link delay is determined based on the second reception time of the second SSB; the second SSB refers to the first SSB in the next synchronization period adjacent to the first synchronization period.

[0027] Based on the first power supply link delay and the second power supply link delay, the power supply link delay difference before the satellite equipment passes overhead corresponding to the first synchronization period is obtained;

[0028] Based on the second and third power supply link delays, the power supply link delay difference after the satellite equipment passes overhead during the first synchronization period is obtained.

[0029] Optionally, the step of evenly distributing the feeder link delay difference to each of the time slots to be adjusted, based on the position of the first time slot head and the overhead status of the satellite equipment, to obtain the target time slot, includes:

[0030] When the overhead situation indicates that the satellite equipment is overhead within the first synchronization period, the power supply link delay difference before the satellite equipment is overhead is evenly distributed to each of the time slots to be adjusted before the satellite equipment is overhead, according to the position of the first time slot head and the direction of movement of the satellite equipment relative to the ground gateway station.

[0031] Based on the position of the first time slot head and the direction of movement of the satellite equipment relative to the ground gateway station, the power supply link delay difference after the satellite equipment passes overhead is evenly distributed to each of the time slots to be adjusted after the satellite equipment passes overhead.

[0032] Optional, also includes:

[0033] Based on the satellite equipment's overhead position information, ephemeris information, and ground gateway station position information, determine whether the satellite equipment has passed overhead during the first synchronization period.

[0034] This application also provides a downlink synchronization device, including:

[0035] The first determining module is used to determine the position of the first time slot head of the time slot to be adjusted corresponding to the first synchronization period and the power supply link delay difference corresponding to the first synchronization period, wherein the time slot to be adjusted is a predicted time slot.

[0036] The first adjustment module is used to adjust the duration of the time slot to be adjusted according to the position of the first time slot head and the delay difference of the power supply link, so as to obtain the target time slot;

[0037] The first synchronization module is used to perform downlink synchronization operations according to the target time slot.

[0038] Optionally, determining the position of the first time slot header corresponding to the first synchronization period includes:

[0039] Based on at least one synchronization signal block (SSB) received within the first synchronization period, the second time slot header position of the time slot where the at least one SSB is located is obtained;

[0040] Based on the position of the second time slot head, the position of the first time slot head of the time slot to be adjusted is inferred.

[0041] Optionally, adjusting the duration of the time slot to be adjusted based on the position of the first time slot header and the delay difference of the power supply link to obtain the target time slot includes:

[0042] Based on the position of the first time slot head and the overhead status of the satellite equipment, the power supply link delay difference is evenly distributed to each of the time slots to be adjusted to obtain the target time slot;

[0043] The term "overhead" refers to the area above a ground gateway station during the movement of satellite equipment.

[0044] Optionally, the step of evenly distributing the feeder link delay difference to each of the time slots to be adjusted, based on the position of the first time slot head and the overhead status of the satellite equipment, to obtain the target time slot, includes:

[0045] The average value of the power supply link delay difference is obtained based on the number of the first timeslot header positions;

[0046] Based on the average value and the overhead position of the satellite equipment, the first time slot head position of each of the time slots to be adjusted is adjusted to obtain the target time slot.

[0047] Optionally, determining the power supply link delay difference corresponding to the first synchronization period includes:

[0048] If the overpass situation indicates that the satellite equipment does not pass overpass within the first synchronization period, the power supply link delay difference corresponding to the first synchronization period is determined based on the first reception time of the first SSB and the second reception time of the second SSB received within the first synchronization period.

[0049] The second SSB refers to the first SSB in the next synchronization period adjacent to the first synchronization period.

[0050] Optionally, the step of evenly distributing the feeder link delay difference to each of the time slots to be adjusted, based on the position of the first time slot head and the overhead status of the satellite equipment, to obtain the target time slot, includes:

[0051] If the overhead condition indicates that the satellite equipment will not be overhead during the first synchronization period, the power supply link delay difference is evenly distributed to each of the time slots to be adjusted according to the position of the first time slot head and the direction of movement of the satellite equipment relative to the ground gateway station, so as to obtain the target time slot.

[0052] Optionally, determining the power supply link delay difference corresponding to the first synchronization period includes:

[0053] When the overhead situation indicates that the satellite equipment is overhead within the first synchronization period, the first power supply link delay is obtained based on the first reception time of the first SSB received within the first synchronization period.

[0054] Based on the satellite equipment's overhead position information, determine the second feeder link delay corresponding to the satellite equipment's overhead position;

[0055] The third power supply link delay is determined based on the second reception time of the second SSB; the second SSB refers to the first SSB in the next synchronization period adjacent to the first synchronization period.

[0056] Based on the first power supply link delay and the second power supply link delay, the power supply link delay difference before the satellite equipment passes overhead corresponding to the first synchronization period is obtained;

[0057] Based on the second and third power supply link delays, the power supply link delay difference after the satellite equipment passes overhead during the first synchronization period is obtained.

[0058] Optionally, the step of evenly distributing the feeder link delay difference to each of the time slots to be adjusted, based on the position of the first time slot head and the overhead status of the satellite equipment, to obtain the target time slot, includes:

[0059] When the overhead situation indicates that the satellite equipment is overhead within the first synchronization period, the power supply link delay difference before the satellite equipment is overhead is evenly distributed to each of the time slots to be adjusted before the satellite equipment is overhead, according to the position of the first time slot head and the direction of movement of the satellite equipment relative to the ground gateway station.

[0060] Based on the position of the first time slot head and the direction of movement of the satellite equipment relative to the ground gateway station, the power supply link delay difference after the satellite equipment passes overhead is evenly distributed to each of the time slots to be adjusted after the satellite equipment passes overhead.

[0061] Optional, also includes:

[0062] The second determining module is used to determine whether the satellite equipment has passed overhead within the first synchronization period based on the satellite equipment's overhead position information, ephemeris information, and ground gateway station position information.

[0063] This application embodiment also provides a downlink synchronization device, including: a processor;

[0064] The processor is used to determine the first time slot header position of the time slot to be adjusted corresponding to the first synchronization period and the power supply link delay difference corresponding to the first synchronization period, wherein the time slot to be adjusted is a predicted time slot.

[0065] Based on the position of the first time slot header and the delay difference of the power supply link, the duration of the time slot to be adjusted is adjusted to obtain the target time slot;

[0066] Downlink synchronization is performed based on the target time slot.

[0067] Optionally, determining the position of the first time slot header corresponding to the first synchronization period includes:

[0068] Based on at least one synchronization signal block (SSB) received within the first synchronization period, the second time slot header position of the time slot where the at least one SSB is located is obtained;

[0069] Based on the position of the second time slot head, the position of the first time slot head of the time slot to be adjusted is inferred.

[0070] Optionally, adjusting the duration of the time slot to be adjusted based on the position of the first time slot header and the delay difference of the power supply link to obtain the target time slot includes:

[0071] Based on the position of the first time slot head and the overhead status of the satellite equipment, the power supply link delay difference is evenly distributed to each of the time slots to be adjusted to obtain the target time slot;

[0072] The term "overhead" refers to the area above a ground gateway station during the movement of satellite equipment.

[0073] Optionally, the step of evenly distributing the feeder link delay difference to each of the time slots to be adjusted, based on the position of the first time slot head and the overhead status of the satellite equipment, to obtain the target time slot, includes:

[0074] The average value of the power supply link delay difference is obtained based on the number of the first timeslot header positions;

[0075] Based on the average value and the overhead position of the satellite equipment, the first time slot head position of each of the time slots to be adjusted is adjusted to obtain the target time slot.

[0076] Optionally, determining the power supply link delay difference corresponding to the first synchronization period includes:

[0077] If the overpass situation indicates that the satellite equipment does not pass overpass within the first synchronization period, the power supply link delay difference corresponding to the first synchronization period is determined based on the first reception time of the first SSB and the second reception time of the second SSB received within the first synchronization period.

[0078] The second SSB refers to the first SSB in the next synchronization period adjacent to the first synchronization period.

[0079] Optionally, the step of evenly distributing the feeder link delay difference to each of the time slots to be adjusted, based on the position of the first time slot head and the overhead status of the satellite equipment, to obtain the target time slot, includes:

[0080] If the overhead condition indicates that the satellite equipment will not be overhead during the first synchronization period, the power supply link delay difference is evenly distributed to each of the time slots to be adjusted according to the position of the first time slot head and the direction of movement of the satellite equipment relative to the ground gateway station, so as to obtain the target time slot.

[0081] Optionally, determining the power supply link delay difference corresponding to the first synchronization period includes:

[0082] When the overhead situation indicates that the satellite equipment is overhead within the first synchronization period, the first power supply link delay is obtained based on the first reception time of the first SSB received within the first synchronization period.

[0083] Based on the satellite equipment's overhead position information, determine the second feeder link delay corresponding to the satellite equipment's overhead position;

[0084] The third power supply link delay is determined based on the second reception time of the second SSB; the second SSB refers to the first SSB in the next synchronization period adjacent to the first synchronization period.

[0085] Based on the first power supply link delay and the second power supply link delay, the power supply link delay difference before the satellite equipment passes overhead corresponding to the first synchronization period is obtained;

[0086] Based on the second and third power supply link delays, the power supply link delay difference after the satellite equipment passes overhead during the first synchronization period is obtained.

[0087] Optionally, the step of evenly distributing the feeder link delay difference to each of the time slots to be adjusted, based on the position of the first time slot head and the overhead status of the satellite equipment, to obtain the target time slot, includes:

[0088] When the overhead situation indicates that the satellite equipment is overhead within the first synchronization period, the power supply link delay difference before the satellite equipment is overhead is evenly distributed to each of the time slots to be adjusted before the satellite equipment is overhead, according to the position of the first time slot head and the direction of movement of the satellite equipment relative to the ground gateway station.

[0089] Based on the position of the first time slot head and the direction of movement of the satellite equipment relative to the ground gateway station, the power supply link delay difference after the satellite equipment passes overhead is evenly distributed to each of the time slots to be adjusted after the satellite equipment passes overhead.

[0090] Optionally, the processor is further configured to:

[0091] Based on the satellite equipment's overhead position information, ephemeris information, and ground gateway station position information, determine whether the satellite equipment has passed overhead during the first synchronization period.

[0092] This application also provides a downlink synchronization device, including a memory, a processor, and a program stored in the memory and executable on the processor; when the processor executes the program, it implements the downlink synchronization method described above.

[0093] This application also provides a readable storage medium storing a program that, when executed by a processor, implements the steps in the downlink synchronization method described above.

[0094] This application also provides a computer program product, including computer instructions, which, when executed by a processor, implement the steps of the downlink synchronization method described above.

[0095] The beneficial effects of the above technical solution in this application are as follows:

[0096] In the above scheme, the downlink synchronization method determines the position of the first time slot header corresponding to the first synchronization period and the feed link delay difference corresponding to the first synchronization period, wherein the time slot to be adjusted is a predicted time slot; the duration of the time slot to be adjusted is adjusted according to the position of the first time slot header and the feed link delay difference to obtain the target time slot; and downlink synchronization operation is performed according to the target time slot. This method can reduce the synchronization error of the time slot by adjusting the time slot, so that the cumulative error of on-board time synchronization within a period is minimized, thereby successfully adjusting the effective time of the beam control command, ensuring the successful demodulation of all time slot symbols within the period, achieving accurate downlink synchronization, and solving the problem that the downlink synchronization scheme cannot be accurately implemented in satellite communication scenarios under transparent forwarding mode in the prior art. Attached Figure Description

[0097] Figure 1 This is a synchronization diagram of an embodiment of this application;

[0098] Figure 2 This is a schematic diagram illustrating a demodulation failure scenario in an embodiment of this application.

[0099] Figure 3 This is a schematic diagram of the downlink synchronization method according to an embodiment of this application;

[0100] Figure 4 This is a schematic diagram of time slot head detection according to an embodiment of this application;

[0101] Figure 5 This is a schematic diagram illustrating the case where the satellite does not pass overhead, according to an embodiment of this application.

[0102] Figure 6 This is a schematic diagram illustrating the satellite overhead situation according to an embodiment of this application;

[0103] Figure 7 This is a schematic diagram of time slot adjustment in an embodiment of this application. Figure 1 ;

[0104] Figure 8 This is a schematic diagram of time slot adjustment in an embodiment of this application. Figure 2 ;

[0105] Figure 9 This is a schematic diagram of the downlink synchronization device structure according to an embodiment of this application;

[0106] Figure 10 This is a schematic diagram of the downlink synchronization device structure according to an embodiment of this application. Detailed Implementation

[0107] To make the technical problems, technical solutions and advantages of this application clearer, a detailed description will be provided below in conjunction with the accompanying drawings and specific embodiments.

[0108] The following is a brief introduction to the relevant content of this plan.

[0109] Currently, satellite (equipment) and terrestrial communication have two architectures: regenerative mode and transparent forwarding mode. In low-Earth orbit (LEO) beam-hopping systems, based on regenerative mode, both the NTN (non-terrestrial network) base station (responsible for data transmission) and the beam controller (responsible for beam switching) are located on the satellite. The advantage of this layout is that they can use the same clock, thus easily achieving precise time synchronization. Furthermore, in this mode, only the synchronization between the satellite and the ground terminal is required, and this synchronization method is technically relatively mature. In contrast, in transparent forwarding mode, the NTN base station (responsible for data transmission) is located on the ground, while the beam controller (responsible for beam switching) is located on the satellite. If flexible beam control is desired through the terrestrial NTN base station, such as achieving SSB (synchronization signal block) symbol-level or time slot-level scanning and adapting to dynamic service changes, synchronization between the terrestrial NTN base station and the beam controller on the satellite is essential. Figure 1 As shown:

[0110] A certain beam serves as beam position 1 in slot 0, transmitting SSB0 and SSB1; and during the on-board beam switching, it jumps to beam position 2 (slot 1) to provide service, transmitting SSB2 and SSB3. The beam controller on the satellite is responsible for controlling the on-board beam switching, while the NTN base station is responsible for data transmission and reception on the broadcast and service channels. Due to the satellite's movement, the satellite-to-ground distance is constantly changing. If the two cannot maintain time synchronization, beam switching that is too early or too late will affect data transmission and reception before and after the on-board beam switching time shown in the diagram.

[0111] However, due to the high-speed movement of the satellite, the time delay of the feed link changes, causing the transparent stream time slot from the ground to the satellite to be compressed or lengthened. Therefore, determining the activation time of wave control by finding the frame header or time slot header after capturing the downlink SSB signal using crystal oscillator counting has a certain degree of error. For example, based on the search for the SSB synchronization signal, a synchronization calibration can be completed every 40ms (i.e., one cycle, synchronization cycle). Calculated based on the satellite's maximum relative speed of 7.9km / s, a cumulative time deviation (time difference) of approximately 1μs can be generated within one cycle. Based on this, if... Figure 2 As shown, the accumulated time offset in the latter part of a period is relatively large, which can cause demodulation failure due to the loss of part of the cyclic prefix (CP) in the symbol header or part of the data sampling points in the tail of some time slots. Specifically, the accumulated time offset corresponding to the current time slot will affect the tail of the current time slot or the CP of the symbol header in the next time slot. Figure 2 The above is a simplified illustration, showing the symbol head loss and tail loss on a single time slot (slot X), but it is not limited to this. Figure 2 OFDM stands for Orthogonal Frequency Division Multiplexing.

[0112] Based on the above, this application addresses the problem in existing technologies where downlink synchronization schemes cannot be accurately implemented in satellite communication scenarios under transparent forwarding mode. It provides a downlink synchronization method applicable to satellite equipment, such as... Figure 3 As shown, it includes:

[0113] Step 31: Determine the position of the first time slot head corresponding to the first synchronization period and the power supply link delay difference corresponding to the first synchronization period. The time slot to be adjusted is a predicted time slot (e.g., a time slot predicted by crystal oscillator counting).

[0114] Step 32: Adjust the duration of the time slot to be adjusted according to the position of the first time slot head and the delay difference of the power supply link to obtain the target time slot;

[0115] Step 33: Perform downlink synchronization operation according to the target time slot.

[0116] The downlink synchronization method provided in this application determines the position of the first time slot header corresponding to the first synchronization period and the feed link delay difference corresponding to the first synchronization period, wherein the time slot to be adjusted is a predicted time slot; the duration of the time slot to be adjusted is adjusted according to the position of the first time slot header and the feed link delay difference to obtain the target time slot; and downlink synchronization operation is performed according to the target time slot; it can support reducing the synchronization error of the time slot by adjusting the time slot, so that the cumulative error of on-board time synchronization within a period is minimized, thereby successfully adjusting the effective time of the beam control command, ensuring the successful demodulation of all time slot symbols within the period, achieving accurate downlink synchronization, and solving the problem that the downlink synchronization scheme cannot be accurately implemented in satellite communication scenarios under transparent forwarding mode in the prior art.

[0117] The step of determining the first time slot head position of the time slot to be adjusted corresponding to the first synchronization period includes: obtaining the second time slot head position of the time slot where the at least one synchronization signal block (SSB) is located based on the at least one synchronization signal block (SSB) received within the first synchronization period; and inferring the first time slot head position of the time slot to be adjusted based on the second time slot head position. This allows for accurate determination of the first time slot head position. The phrase "inferring the first time slot head position of the time slot to be adjusted based on the second time slot head position" can include: inferring the first time slot head position of the time slot to be adjusted based on the second time slot head position and the correspondence between the crystal oscillator (count) and the duration; specifically, inferring the first time slot head position of the time slot to be adjusted based on the second time slot head position and the correspondence between the crystal oscillator (count) and the duration can include: obtaining the time slot length based on the correspondence between the crystal oscillator (count) and the duration; inferring the first time slot head position of the time slot to be adjusted (i.e., the subsequent time slot head position after the second time slot head position in this cycle) based on the second time slot head position and the time slot length; wherein, the first synchronization cycle can correspond to (or include): the time slot where at least one SSB is located + the time slot to be adjusted (i.e., the subsequent time slot of the time slot where the SSB is located), but is not limited thereto.

[0118] In this embodiment, adjusting the duration of the time slot to be adjusted based on the position of the first time slot header and the power supply link delay difference to obtain the target time slot includes: distributing the power supply link delay difference equally among the time slots to be adjusted based on the position of the first time slot header and the (predicted) overhead transit of the satellite equipment to obtain the target time slot; wherein, overhead transit refers to the satellite equipment passing over the area above the ground gateway station during its movement. This allows for accurate time slot adjustment for multiple scenarios.

[0119] The step of distributing the power supply link delay difference equally among the time slots to be adjusted based on the position of the first time slot header and the overhead transit of the satellite equipment to obtain the target time slot includes: obtaining the average value of the power supply link delay difference based on the number of first time slot header positions; and adjusting the position of the first time slot header of each of the time slots to be adjusted based on the average value and the overhead transit of the satellite equipment to obtain the target time slot. This allows for precise and accurate time slot adjustment.

[0120] In this embodiment of the application, determining the feeder link delay difference corresponding to the first synchronization period includes: when the overpass condition indicates that the satellite equipment (will) not pass over the top during the first synchronization period, determining the feeder link delay difference corresponding to the first synchronization period based on the first reception time of the first SSB and the second reception time of the second SSB received during the first synchronization period; wherein, the second SSB refers to the first SSB in the next synchronization period adjacent to the first synchronization period. This allows for the specific determination of the feeder link delay difference when the satellite does not pass over the top.

[0121] The step of distributing the feeder link delay difference equally among the time slots to be adjusted based on the position of the first time slot head and the overpass status of the satellite equipment to obtain the target time slot includes: when the overpass status indicates that the satellite equipment will not overpass within the first synchronization period, distributing the feeder link delay difference equally among the time slots to be adjusted based on the position of the first time slot head and the movement direction of the satellite equipment relative to the ground gateway station to obtain the target time slot. This can specifically realize time slot adjustment when the satellite does not overpass. Specifically, when the "movement direction of the satellite equipment relative to the ground gateway station" indicates that the satellite equipment is moving closer to the ground gateway station, the time slot to be adjusted can be shortened (shortened by subtracting the average value of the feeder link delay difference); and / or, when the "movement direction of the satellite equipment relative to the ground gateway station" indicates that the satellite equipment is moving away from the ground gateway station, the time slot to be adjusted can be lengthened (increased by increasing the average value of the feeder link delay difference), but is not limited to this.

[0122] In this embodiment, determining the feeder link delay difference corresponding to the first synchronization period includes: when the overhead situation indicates that the satellite equipment will (be) overhead within the first synchronization period, obtaining the first feeder link delay based on the first reception time of the first SSB received within the first synchronization period; determining the second feeder link delay corresponding to the overhead position information of the satellite equipment based on the overhead position information of the satellite equipment; determining the third feeder link delay based on the second reception time of the second SSB; the second SSB refers to the first SSB in the next synchronization period adjacent to the first synchronization period; obtaining the feeder link delay difference before the overhead position of the satellite equipment corresponding to the first synchronization period based on the first feeder link delay and the second feeder link delay; and obtaining the feeder link delay difference after the overhead position of the satellite equipment corresponding to the first synchronization period based on the second feeder link delay and the third feeder link delay. This allows for the specific determination of the feeder link delay difference under the satellite overhead situation. The "overhead position information" can be manually input or obtained through other methods, and is not limited here.

[0123] The step of distributing the feeder link delay difference equally among the time slots to be adjusted, based on the position of the first time slot header and the satellite equipment's overhead transit, to obtain the target time slot includes: when the overhead transit indicates that the satellite equipment is overhead within the first synchronization period, distributing the feeder link delay difference before the satellite equipment's overhead transit equally among the time slots to be adjusted before the satellite equipment's overhead transit, based on the position of the first time slot header and the direction of movement of the satellite equipment relative to the ground gateway station; and distributing the feeder link delay difference after the satellite equipment's overhead transit equally among the time slots to be adjusted after the satellite equipment's overhead transit, based on the position of the first time slot header and the direction of movement of the satellite equipment relative to the ground gateway station. This specifically enables time slot adjustment in the case of satellite overhead transit. Specifically, when the "direction of movement of the satellite equipment relative to the ground gateway station" indicates that the satellite equipment is moving towards the ground gateway station, the time slot to be adjusted can be shortened (shortened by subtracting the average value of the power supply link delay difference); and / or, when the "direction of movement of the satellite equipment relative to the ground gateway station" indicates that the satellite equipment is moving away from the ground gateway station, the time slot to be adjusted can be extended (increased by increasing the average value of the power supply link delay difference), but this is not a limitation. In addition, in this scheme, the overpass time of the satellite equipment may not fall exactly at the junction of two time slots, but may fall in the middle of a time slot (i.e., within a time slot). In this case, the time slot head position of that time slot will be located before the overpass, and that time slot can be classified as part of the part before the overpass (i.e., as the time slot to be adjusted before the overpass); and / or, the time slot with the time slot head position before the overpass time can be regarded as the "time slot to be adjusted before the overpass of the satellite equipment", and the time slot with the time slot head position after the overpass time can be regarded as the "time slot to be adjusted after the overpass of the satellite equipment", but this is not a limitation.

[0124] To clarify, in both the overpass and non-overpass scenarios, "determining the feeder link delay difference corresponding to the first synchronization period" can also be described as: obtaining the first feeder link delay and the third feeder link delay; determining the feeder link delay difference corresponding to the first synchronization period based on the first feeder link delay and the third feeder link delay. Correspondingly, for the overpass scenario, "determining the feeder link delay difference corresponding to the first synchronization period" can further include: determining the second feeder link delay; the step of determining the feeder link delay difference corresponding to the first synchronization period based on the first feeder link delay and the third feeder link delay can include: obtaining the feeder link delay difference before the satellite equipment overpasses the first synchronization period based on the first feeder link delay and the second feeder link delay; obtaining the feeder link delay difference after the satellite equipment overpasses the first synchronization period based on the second feeder link delay and the third feeder link delay. Accordingly, regarding the case of not exceeding the top, obtaining the first power supply link delay and the third power supply link delay may include: obtaining the first power supply link delay based on the first reception time of the first SSB received within the first synchronization period; determining the third power supply link delay based on the second reception time of the second SSB; the second SSB refers to the first SSB in the next synchronization period adjacent to the first synchronization period. However, this solution is not limited to the foregoing content.

[0125] Furthermore, the downlink synchronization method further includes: determining whether the satellite equipment passes overhead within the first synchronization period based on the satellite equipment's overhead position information, ephemeris information, and ground gateway station position information. This allows for accurate determination of the satellite equipment's overhead status. Specifically, determining whether the satellite equipment passes overhead within the first synchronization period based on the satellite equipment's overhead position information, ephemeris information, and ground gateway station position information can include: determining the absolute time of the satellite's overhead passage based on the satellite equipment's overhead position information, ephemeris information, and ground gateway station position information; and determining whether the satellite equipment passes overhead within the first synchronization period based on the absolute time. Specifically, determining whether the satellite equipment passes overhead within the first synchronization period based on the absolute time can include: determining that the satellite equipment will not pass overhead within the first synchronization period if the first synchronization period does not include the absolute time; and determining that the satellite equipment will pass overhead within the first synchronization period if the first synchronization period includes the absolute time, but this is not a limitation.

[0126] The following is an example of the downlink synchronization method provided in the embodiments of this application. The number of at least one SSB received in the first synchronization period is taken as two (including the first SSB and the second SSB).

[0127] To address the aforementioned technical problems, this application provides a downlink synchronization method, specifically a downlink synchronization method based on transparent transmission mode (i.e., transparent forwarding mode) (more specifically, a downlink synchronization method for satellite communication scenarios in transparent forwarding mode), minimizing the cumulative on-board time synchronization error within a (synchronization) cycle and achieving accurate downlink synchronization. Specifically, this solution may include the following operations:

[0128] Operation 1: The satellite synchronization module (of the satellite equipment) searches for SSB signals in the corresponding frequency band of the satellite and performs time slot head detection.

[0129] First, the satellite receives the NR NTN air interface signal transmitted via the feed link (this signal can be used to trigger downlink synchronization; this air interface signal contains the SSB signal), and searches for the first SSB signal (i.e., SSB0) through real-time correlation detection (of this air interface signal). Then, according to the protocol, the SSB header is pushed forward by several OFDM (Orthogonal Frequency Division Multiplexing) symbols to find the slot header of slot 0 where the SSB is located, achieving symbol-level synchronization for that slot. Figure 4 As shown, the satellite synchronization module can read the SSB signals of two time slots within each SSB period T (i.e., the synchronization period). By searching for the SSB signal of the second time slot (i.e., SSB2), the time slot header of slot 1 can be determined. At this point, symbol-level synchronization of the first two time slots, slots 0 and 1, has been completed; this corresponds to obtaining the second time slot header position of the time slot containing the at least one synchronization signal block (SSB) received within the first synchronization period. Subsequently, based on the determined time slot header positions and empirical values ​​(such as a specific number of crystal oscillators corresponding to a certain time length, i.e., the correspondence between crystal oscillators and time length), the positions of subsequent time slot headers in this period can be preliminarily inferred (corresponding to the above-mentioned estimation of the first time slot header position of the time slot to be adjusted based on the second time slot header position, where the time slot to be adjusted is the estimated time slot), thereby determining the time slot where the beam control activation time is located (e.g., a certain time slot header where the activation time is located). Figure 4 In this context, N represents the number of time slots contained within the period T.

[0130] Operation 2: The satellite side performs an overhead detection, (predicting) whether the satellite will pass overhead within this period.

[0131] In this scheme, the feeder link delay difference caused by satellite movement within a cycle is calculated and linearly distributed to each (to be adjusted) time slot (to compress or extend the local satellite time slot corresponding to the activation of beam control) to achieve more accurate downlink time synchronization. Therefore, whether the satellite passes overhead is related to the calculation method of the feeder circuit delay difference and the method of linear distribution.

[0132] Based on the above, this solution considers adding a mechanism to determine whether the satellite passes overhead: The satellite is known to obtain ephemeris information and store the location of the ground gateway station (the gateway station can be used to forward information between the satellite and the ground base station). By inputting the overhead location information (such as geographical location information), the absolute time of the overhead passage can be obtained. This absolute time can be used to determine whether the satellite passes overhead (i.e., whether the satellite passes above the ground gateway station during its movement). Corresponding to the above, based on the overhead location information, ephemeris information, and ground gateway station location information of the satellite equipment, it is determined whether the satellite equipment passes overhead within the first synchronization period.

[0133] If the period (i.e., synchronization period) of the SSB searched in Operation 1 does not include the absolute time of the satellite's overhead transit, it indicates that the satellite has not passed overhead. Then, the cumulative delay difference (i.e., feeder link delay difference Δ) can be calculated according to Operation 3, and this delay difference can be linearly divided according to the rules of Operation 5. If the period of the SSB searched in Operation 1 includes the absolute time of the satellite's overhead transit, it indicates that the satellite has passed overhead. Then, the cumulative delay difference (i.e., feeder link delay difference Δ1 before overhead transit, and feeder link delay difference Δ2 after overhead transit) can be calculated according to Operation 4, and this delay difference can be linearly divided according to the rules of Operation 6. Corresponding to the above, based on the position of the first time slot head and the overhead transit status of the satellite equipment, the feeder link delay difference can be evenly distributed to each of the time slots to be adjusted to obtain the target time slot. Here, overhead transit refers to the satellite equipment passing over the area above the ground gateway station during its movement. The step of distributing the power supply link delay difference equally to each of the time slots to be adjusted to obtain the target time slot based on the position of the first time slot head and the overhead status of the satellite equipment includes: obtaining the average value of the power supply link delay difference based on the number of first time slot head positions; and adjusting the position of the first time slot head of each of the time slots to be adjusted based on the average value and the overhead status of the satellite equipment to obtain the target time slot.

[0134] Operation 3: When the satellite has not passed overhead, calculate the cumulative feeder link delay difference within one cycle (corresponding to the feeder link delay difference corresponding to the first synchronization cycle mentioned above).

[0135] Through the above operations, the satellite synchronization module has searched for the SSB signal and identified the time slot header of the time slot where the SSB is located (corresponding to the position of the second time slot header mentioned above), and determined that the satellite has not passed over the top in this period. Considering that the time change of the satellite position causes the change of the feeder link delay, it is assumed that the function f(t) represents the feeder link delay at time t, which can be obtained from the satellite ephemeris information and the position of the gateway station at time t.

[0136] First, calculate the feeder link delay between the satellite and the ground (gateway station) at the beginning of one cycle. For example... Figure 5As shown, let t0 represent the time when the ground transmits the SSB signal, and t0' represent the time when the satellite receives the SSB signal (corresponding to the first reception time mentioned above). Then, f(t0') = d1' represents the feed link delay at the satellite's location when it receives the SSB signal. Since the SSB signal transmitted from the ground will reach the satellite after a certain feed link delay, and the satellite's position keeps changing during this process, the feed link delay at the satellite's location when the ground transmits the SSB signal can be expressed as f(t0) = d1, where t0 = t0' - d1'. Therefore, the initial feed link delay between the satellite and the ground can be calculated as d = (d1 + d1') / 2.

[0137] Similarly, after one cycle T, the ground transmits the SSB signal again. Now, calculate the feed link delay between the satellite and the ground at the end of one cycle (the specific calculation method can be used, and there are no restrictions here). When the ground transmits the SSB again, the feed link delay (which can be calculated based on the corresponding SSB transmission time on the satellite) is f(t0'-d+T)=d2. Then, when the satellite receives the SSB signal (corresponding to the second reception time of the second SSB mentioned above), the feed link delay is f(t0'-d+T+d2)=d2'. Therefore, the feed link delay between the satellite and the ground at the end of the cycle is d'=(d2+d2') / 2.

[0138] From the above, the feeder link delay difference Δ = |d - d'| within one cycle can be obtained. Subsequently, the time slot header and / or frame header can be adjusted according to operation 5. The acquisition of Δ in this operation corresponds to the above-mentioned case where the satellite equipment does not pass over the top in the first synchronization cycle, and the feeder link delay difference corresponding to the first synchronization cycle is determined according to the first reception time of the first SSB and the second reception time of the second SSB received in the first synchronization cycle; wherein, the second SSB refers to the first SSB in the next synchronization cycle adjacent to the first synchronization cycle.

[0139] In this operation, the time when the ground sends the SSB signal can be eliminated during the actual calculation. The relevant feeder link delay can be obtained based on the corresponding satellite reception time, but this is not a limitation.

[0140] Operation 4: When the satellite passes overhead, calculate the feeder link delay difference before and after the overhead pass within one cycle.

[0141] If we consider the satellite passing overhead within one cycle, we can calculate the accumulated feeder link delay difference before the satellite passes overhead and the accumulated feeder link delay difference after the satellite passes overhead.

[0142] See operation 3, such as Figure 6As shown, within one cycle, the initial and final feed link delays between the satellite and the ground can be expressed as d = (d1 + d1') / 2 (corresponding to the first feed link delay mentioned above) and d' = (d2 + d2') / 2 (corresponding to the third feed link delay mentioned above), respectively. Since the satellite's overpass position information is known, the feed link delay 'd' at the time of overpass can be directly obtained (using the current method). Therefore, the feed link delay difference before overpass Δ1 = |dd”|, and the feed link delay difference after overpass Δ2 = |d”-d'|. This operation corresponds to the situation described above where the satellite equipment overpasses within the first synchronization period, based on the first reception time of the first SSB received within the first synchronization period, obtaining the first feed link delay; determining the second feed link delay corresponding to the satellite equipment's overpass position information based on the satellite equipment's overpass position information; determining the third feed link delay based on the second reception time of the second SSB; the second SSB refers to the first SSB in the next synchronization period adjacent to the first synchronization period; obtaining the feed link delay difference before the satellite equipment overpasses in the first synchronization period based on the first feed link delay and the second feed link delay; and obtaining the feed link delay difference after the satellite equipment overpasses in the first synchronization period based on the second feed link delay and the third feed link delay.

[0143] Operation 5: When the satellite has not passed overhead, the power supply link delay difference will be linearly and evenly distributed into each time slot (to be adjusted this week).

[0144] Specifically, the adjustment amount for each time slot can be determined using linear equal distribution. The cumulative delay difference Δ calculated in operation 3 is evenly distributed to each time slot (this corresponds to obtaining the average value of the feeder link delay difference based on the number of first time slot head positions; adjusting the first time slot head position of each time slot to be adjusted based on the average value and the satellite equipment's overhead condition to obtain the target time slot). It is known that the precise synchronization of the first two time slots, slot0 and slot1, has been completed through operation 1, determining the time slot head positions N of slot0 and slot1. slot0 N slot1 The position of each subsequent time slot head can now be predicted as N using crystal oscillator counting (preliminary). slot2 N slot3 N slot4 ...then, the position of each time slot header obtained (finally) using this scheme is N. slot0 N slot1 N slot2 ±△ / (N-2), N slot3 ±△ / (N-2), N slot4±△ / (N-2)……; where “±” depends on the direction of the satellite’s movement relative to the ground gateway station, as illustrated below; N is the number of time slots in one cycle. This completes the high-precision adjustment of onboard time synchronization before the satellite passes overhead.

[0145] like Figure 7 As shown, when the satellite moves further away from the ground gateway station during this period, the time slots for the transparent stream arriving on the satellite from the ground are lengthened. Therefore, to ensure symbol tail alignment at the end of the period, the time slot corresponding to the beacon control activation time can be lengthened (i.e., the on-board time slots are extended). Since the symbol header is protected by CP, the position of each time slot header can be adjusted to N. slot0 N slot1 N slot2 +△ / (N-2), N slot3 +2×△ / (N-2), N slot4 +3×△ / (N-2)……。 In this scheme, the time slots of the transparent flow are not guaranteed to be completely aligned with the time slots of the adjusted wave control (as long as the time offset can be reduced), and the tail of the last time slot of the entire cycle is aligned, but this is not a limitation.

[0146] like Figure 8 As shown, when the satellite approaches the ground gateway station within this period, the time slots of the transparent stream arriving on the satellite from the ground are compressed. Therefore, the beam control activation time can be advanced, compressing the on-satellite time slots (i.e., compressing the time slots corresponding to the beam control activation time), ensuring the alignment of the symbol tails at the end of the period. Thus, the position of each time slot header can be adjusted to N. slot0 N slot1 N slot2 -△ / (N-2), N slot3 -2×△ / (N-2), N slot4 -3×△ / (N-2)……

[0147] For example, within a 40ms period, assuming a maximum relative speed of 7.9km / s, the maximum cumulative error (i.e., feeder link delay difference) due to the time delay variation in the feeder link caused by satellite movement is 1μs. Therefore, when the satellite synchronization module searches for the SSB signal and obtains the two accurate time slot headers N for the first two periods of that period... slot0 N slot1 Subsequently, in this scheme, the 1μs error will be averaged over the remaining 38 time slots. Specifically, the time slot header N, obtained by the crystal oscillator counting method, will be... slot2 N slot3 ... N slot39 It can be moved forward or backward by 1μs / 38 in sequence.

[0148] In this operation, the handling of the power supply link delay difference can correspond to the situation described above where the satellite equipment does not pass over the top during the first synchronization period, and the power supply link delay difference is evenly distributed to each of the time slots to be adjusted according to the position of the first time slot head and the direction of movement of the satellite equipment relative to the ground gateway station, so as to obtain the target time slot.

[0149] Operation 6: When the satellite passes overhead, the feeder link delay difference before and after the overhead is equally distributed into two time slots.

[0150] Operation 4 yields the feed link delay differences Δ1 and Δ2 before and after the satellite's overhead transit. To ensure symbol tail alignment at the end of a cycle, these delay differences Δ1 and Δ2 are linearly and evenly distributed into the time slots before and after the overhead transit, respectively. Assume the satellite obtains, through ephemeris and overhead transit position information, that the number of time slots before and after the overhead transit within a cycle is N1 and N2, respectively; where N1 + N2 = N, and N represents the total number of time slots within a cycle. In this scheme, the time slot header positions of slot0 and slot1 remain unchanged. Δ1 is linearly and evenly distributed into the first N1-2 time slots, and Δ2 is linearly and evenly distributed into the last N2 time slots.

[0151] Specifically:

[0152] In this scheme, operation 1 has completed the precise symbol-level synchronization of the first two time slots, slot0 and slot1, and determined the time slot header position N of slot0 and slot1. slot0 N slot1 The initial position N for each subsequent time slot is now predicted using crystal oscillator counting. slot2 N slot3 ... N slot(N1-1) N slot(N1) ... N slot(N-1) .after:

[0153] First, the slot header positions of slots 0 and 1 are kept unchanged. The cumulative delay difference Δ1 of the feed link before the overhead pass is linearly and evenly distributed into the first N1-2 slots: since the satellite moves closer to the ground gateway station during this period, the beam control command (corresponding to beam control activation) can be sent earlier, and the slot header positions of the first N1 slots are adjusted to N. slot0 N slot1 N slot2 -△1 / (N1-2), N slot3 -2×△1 / (N1-2), ..., N slot(N1-1) -△1. In the N2 time slots after the satellite passes over the top, the cumulative delay difference △2 of the feeder link is linearly divided: since the satellite is moving away from the ground gateway station, the transmission of the beam control command can be delayed, and the position of the N2 time slots after the satellite passes over the top can be adjusted to N.slotN1 -△1+△2 / N2、N slot(N1+1) -△1+2×△2 / N2、……、N slot(N-1) -△1+△2. This yields the adjustment result of the beam control activation time slot under satellite overpass conditions. The correspondence between the beam control activation time and the time slot can remain unchanged, but is not a limitation thereof.

[0154] In this operation, the handling of the power supply link delay difference corresponds to the situation described above where, in the case of the satellite equipment passing over the top during the first synchronization period, the power supply link delay difference before the satellite equipment passes over the top is evenly distributed to each of the time slots to be adjusted before the satellite equipment passes over the top, based on the position of the first time slot head and the direction of movement of the satellite equipment relative to the ground gateway station; and the power supply link delay difference after the satellite equipment passes over the top is evenly distributed to each of the time slots to be adjusted after the satellite equipment passes over the top, based on the position of the first time slot head and the direction of movement of the satellite equipment relative to the ground gateway station.

[0155] Therefore, the solutions provided in the embodiments of this application mainly involve:

[0156] 1. The downlink synchronization cumulative error within a cycle is evenly distributed to each (to be adjusted) time slot, successfully adjusting the effective time of the beam control command and achieving more accurate downlink synchronization, which can support successful demodulation of symbols in all time slots.

[0157] 2. Add a satellite over-the-top mechanism: By inputting the satellite over-the-top position information, and based on the ephemeris information and the gateway station position, it is determined whether the satellite has over-the-top. When the satellite has not over-the-top, the accumulated feeder link delay difference within the period is simply divided equally; when the satellite has over-the-top, the accumulated feeder link delay difference before and after the over-the-top is linearly divided equally in the corresponding manner.

[0158] In summary, this solution has the following advantages:

[0159] 1. Improved downlink synchronization accuracy in transparent transmission mode, reduced synchronization error in each time slot, minimized cumulative on-board synchronization error, and thus ensured successful demodulation of symbols in all time slots within the cycle.

[0160] 2. The solution is simple and easy to implement.

[0161] 3. A satellite overpass detection mechanism was added, which improved the applicable scenarios of the scheme and further optimized the synchronization performance.

[0162] This application also provides a downlink synchronization device, such as... Figure 9 As shown, it includes:

[0163] The first determining module 91 is used to determine the first time slot head position of the time slot to be adjusted corresponding to the first synchronization period and the power supply link delay difference corresponding to the first synchronization period, wherein the time slot to be adjusted is a predicted time slot.

[0164] The first adjustment module 92 is used to adjust the duration of the time slot to be adjusted according to the position of the first time slot head and the delay difference of the power supply link, so as to obtain the target time slot;

[0165] The first synchronization module 93 is used to perform downlink synchronization operation according to the target time slot.

[0166] The downlink synchronization device provided in this application determines the position of the first time slot header corresponding to the first synchronization period and the feed link delay difference corresponding to the first synchronization period, wherein the time slot to be adjusted is a predicted time slot; the duration of the time slot to be adjusted is adjusted according to the position of the first time slot header and the feed link delay difference to obtain the target time slot; and downlink synchronization operation is performed according to the target time slot; it can support reducing the synchronization error of the time slot by adjusting the time slot, so that the cumulative error of on-board time synchronization within a period is minimized, thereby successfully adjusting the effective time of the beam control command, ensuring the successful demodulation of all time slot symbols within the period, achieving accurate downlink synchronization, and solving the problem that the downlink synchronization scheme cannot be accurately implemented in satellite communication scenarios under transparent forwarding mode in the prior art.

[0167] The step of determining the first time slot head position of the time slot to be adjusted corresponding to the first synchronization period includes: obtaining the second time slot head position of the time slot where the at least one synchronization signal block (SSB) is located based on the at least one synchronization signal block (SSB) received within the first synchronization period; and inferring the first time slot head position of the time slot to be adjusted based on the second time slot head position.

[0168] In this embodiment of the application, adjusting the duration of the time slot to be adjusted according to the position of the first time slot head and the power supply link delay difference to obtain the target time slot includes: distributing the power supply link delay difference equally to each of the time slots to be adjusted according to the position of the first time slot head and the overhead status of the satellite equipment to obtain the target time slot; wherein, overhead refers to the satellite equipment passing over the area above the ground gateway station during its movement.

[0169] The step of distributing the power supply link delay difference equally to each of the time slots to be adjusted to obtain the target time slot based on the position of the first time slot head and the overhead status of the satellite equipment includes: obtaining the average value of the power supply link delay difference based on the number of first time slot head positions; and adjusting the position of the first time slot head of each of the time slots to be adjusted based on the average value and the overhead status of the satellite equipment to obtain the target time slot.

[0170] In this embodiment of the application, determining the feeder link delay difference corresponding to the first synchronization period includes: when the overpass condition indicates that the satellite equipment does not pass overpass in the first synchronization period, determining the feeder link delay difference corresponding to the first synchronization period based on the first reception time of the first SSB and the second reception time of the second SSB received in the first synchronization period; wherein, the second SSB refers to the first SSB in the next synchronization period adjacent to the first synchronization period.

[0171] The step of distributing the power supply link delay difference equally to each of the time slots to be adjusted to obtain the target time slot based on the position of the first time slot head and the overpass status of the satellite equipment includes: when the overpass status indicates that the satellite equipment will not overpass during the first synchronization period, distributing the power supply link delay difference equally to each of the time slots to be adjusted based on the position of the first time slot head and the direction of movement of the satellite equipment relative to the ground gateway station to obtain the target time slot.

[0172] In this embodiment of the application, determining the feeder link delay difference corresponding to the first synchronization period includes: when the overhead situation indicates that the satellite equipment is overhead within the first synchronization period, obtaining the first feeder link delay based on the first reception time of the first SSB received within the first synchronization period; determining the second feeder link delay corresponding to the overhead position information of the satellite equipment based on the overhead position information of the satellite equipment; determining the third feeder link delay based on the second reception time of the second SSB; the second SSB refers to the first SSB in the next synchronization period adjacent to the first synchronization period; obtaining the feeder link delay difference before the satellite equipment overhead in the first synchronization period based on the first feeder link delay and the second feeder link delay; and obtaining the feeder link delay difference after the satellite equipment overhead in the first synchronization period based on the second feeder link delay and the third feeder link delay.

[0173] The step of distributing the feeder link delay difference equally to each of the time slots to be adjusted, based on the position of the first time slot head and the overpass status of the satellite equipment, to obtain the target time slot includes: when the overpass status indicates that the satellite equipment is overpassing within the first synchronization period, distributing the feeder link delay difference before the satellite equipment overpasses equally to each of the time slots to be adjusted before the satellite equipment overpasses, based on the position of the first time slot head and the direction of movement of the satellite equipment relative to the ground gateway station; and distributing the feeder link delay difference after the satellite equipment overpasses equally to each of the time slots to be adjusted after the satellite equipment overpasses, based on the position of the first time slot head and the direction of movement of the satellite equipment relative to the ground gateway station.

[0174] Furthermore, the downlink synchronization device further includes: a second determining module, used to determine whether the satellite equipment has passed overhead within the first synchronization period based on the satellite equipment's overhead position information, ephemeris information, and ground gateway station position information.

[0175] The implementation embodiments of the downlink synchronization method described above are all applicable to the embodiments of the downlink synchronization device and can achieve the same technical effect.

[0176] This application also provides a downlink synchronization device, such as... Figure 10 As shown, it includes: processor 101;

[0177] The processor 101 is used to determine the first time slot header position of the time slot to be adjusted corresponding to the first synchronization period and the power supply link delay difference corresponding to the first synchronization period, wherein the time slot to be adjusted is a predicted time slot.

[0178] Based on the position of the first time slot header and the delay difference of the power supply link, the duration of the time slot to be adjusted is adjusted to obtain the target time slot;

[0179] Downlink synchronization is performed based on the target time slot.

[0180] The downlink synchronization device provided in this application determines the position of the first time slot header corresponding to the first synchronization period and the feed link delay difference corresponding to the first synchronization period, wherein the time slot to be adjusted is a predicted time slot; the duration of the time slot to be adjusted is adjusted according to the position of the first time slot header and the feed link delay difference to obtain the target time slot; and downlink synchronization operation is performed according to the target time slot; it can support reducing the synchronization error of the time slot by adjusting the time slot, so that the cumulative error of on-board time synchronization within a period is minimized, thereby successfully adjusting the effective time of the beam control command, ensuring the successful demodulation of all time slot symbols within the period, achieving accurate downlink synchronization, and solving the problem that the downlink synchronization scheme cannot be accurately implemented in satellite communication scenarios under transparent forwarding mode in the prior art.

[0181] The step of determining the first time slot head position of the time slot to be adjusted corresponding to the first synchronization period includes: obtaining the second time slot head position of the time slot where the at least one synchronization signal block (SSB) is located based on the at least one synchronization signal block (SSB) received within the first synchronization period; and inferring the first time slot head position of the time slot to be adjusted based on the second time slot head position.

[0182] In this embodiment of the application, adjusting the duration of the time slot to be adjusted according to the position of the first time slot head and the power supply link delay difference to obtain the target time slot includes: distributing the power supply link delay difference equally to each of the time slots to be adjusted according to the position of the first time slot head and the overhead status of the satellite equipment to obtain the target time slot; wherein, overhead refers to the satellite equipment passing over the area above the ground gateway station during its movement.

[0183] The step of distributing the power supply link delay difference equally to each of the time slots to be adjusted to obtain the target time slot based on the position of the first time slot head and the overhead status of the satellite equipment includes: obtaining the average value of the power supply link delay difference based on the number of first time slot head positions; and adjusting the position of the first time slot head of each of the time slots to be adjusted based on the average value and the overhead status of the satellite equipment to obtain the target time slot.

[0184] In this embodiment of the application, determining the feeder link delay difference corresponding to the first synchronization period includes: when the overpass condition indicates that the satellite equipment does not pass overpass in the first synchronization period, determining the feeder link delay difference corresponding to the first synchronization period based on the first reception time of the first SSB and the second reception time of the second SSB received in the first synchronization period; wherein, the second SSB refers to the first SSB in the next synchronization period adjacent to the first synchronization period.

[0185] The step of distributing the power supply link delay difference equally to each of the time slots to be adjusted to obtain the target time slot based on the position of the first time slot head and the overpass status of the satellite equipment includes: when the overpass status indicates that the satellite equipment will not overpass during the first synchronization period, distributing the power supply link delay difference equally to each of the time slots to be adjusted based on the position of the first time slot head and the direction of movement of the satellite equipment relative to the ground gateway station to obtain the target time slot.

[0186] In this embodiment of the application, determining the feeder link delay difference corresponding to the first synchronization period includes: when the overhead situation indicates that the satellite equipment is overhead within the first synchronization period, obtaining the first feeder link delay based on the first reception time of the first SSB received within the first synchronization period; determining the second feeder link delay corresponding to the overhead position information of the satellite equipment based on the overhead position information of the satellite equipment; determining the third feeder link delay based on the second reception time of the second SSB; the second SSB refers to the first SSB in the next synchronization period adjacent to the first synchronization period; obtaining the feeder link delay difference before the satellite equipment overhead in the first synchronization period based on the first feeder link delay and the second feeder link delay; and obtaining the feeder link delay difference after the satellite equipment overhead in the first synchronization period based on the second feeder link delay and the third feeder link delay.

[0187] The step of distributing the feeder link delay difference equally to each of the time slots to be adjusted, based on the position of the first time slot head and the overpass status of the satellite equipment, to obtain the target time slot includes: when the overpass status indicates that the satellite equipment is overpassing within the first synchronization period, distributing the feeder link delay difference before the satellite equipment overpasses equally to each of the time slots to be adjusted before the satellite equipment overpasses, based on the position of the first time slot head and the direction of movement of the satellite equipment relative to the ground gateway station; and distributing the feeder link delay difference after the satellite equipment overpasses equally to each of the time slots to be adjusted after the satellite equipment overpasses, based on the position of the first time slot head and the direction of movement of the satellite equipment relative to the ground gateway station.

[0188] Furthermore, the processor is also used to: determine whether the satellite equipment has passed overhead within the first synchronization period based on the satellite equipment's overhead position information, ephemeris information, and ground gateway station position information.

[0189] The implementation embodiments of the downlink synchronization method described above are all applicable to the embodiments of the downlink synchronization device and can achieve the same technical effect.

[0190] This application also provides a downlink synchronization device, including a memory, a processor, and a program stored in the memory and executable on the processor; when the processor executes the program, it implements the downlink synchronization method described above.

[0191] The implementation embodiments of the downlink synchronization method described above are all applicable to the embodiments of the downlink synchronization device and can achieve the same technical effect.

[0192] This application also provides a readable storage medium storing a program that, when executed by a processor, implements the steps in the downlink synchronization method described above.

[0193] The aforementioned implementation embodiments of the downlink synchronization method are all applicable to the embodiments of the readable storage medium and can achieve the same technical effect.

[0194] This application also provides a computer program product, including computer instructions. When the computer instructions are executed by a processor, they implement the various processes of the above-described downlink synchronization method and achieve the same technical effect. To avoid repetition, they will not be described again here.

[0195] It should be noted that many of the functional components described in this specification are referred to as modules in order to more specifically emphasize the independence of their implementation.

[0196] In this embodiment, the module can be implemented in software so that it can be executed by various types of processors. For example, an identified executable code module may include one or more physical or logical blocks of computer instructions, which may be constructed as objects, procedures, or functions. Nevertheless, the executable code of the identified module does not need to be physically located together, but may include different instructions stored in different bits, which, when logically combined, constitute the module and achieve the module's intended purpose.

[0197] In practice, an executable code module can be a single instruction or many instructions, and can even be distributed across multiple different code segments, different programs, and across multiple memory devices. Similarly, operational data can be identified within the module and can be implemented in any suitable form and organized within any suitable type of data structure. This operational data can be collected as a single dataset or distributed across different locations (including different storage devices), and can exist, at least in part, solely as electronic signals within the system or network.

[0198] When a module can be implemented using software, considering the current level of hardware technology, modules that can be implemented in software can be implemented using hardware circuits by those skilled in the art to achieve the corresponding functions, without considering cost. These hardware circuits include conventional very-large-scale integrated circuits (VLSI) or gate arrays, as well as existing semiconductors such as logic chips and transistors, or other discrete components. Modules can also be implemented using programmable hardware devices, such as field-programmable gate arrays, programmable array logic, and programmable logic devices.

[0199] The above describes the preferred embodiments of this application. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principles described in this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A downlink synchronization method, characterized in that, include: Determine the position of the first time slot header of the time slot to be adjusted corresponding to the first synchronization period and the power supply link delay difference corresponding to the first synchronization period, wherein the time slot to be adjusted is a predicted time slot; Based on the position of the first time slot header and the delay difference of the power supply link, the duration of the time slot to be adjusted is adjusted to obtain the target time slot; Downlink synchronization is performed based on the target time slot.

2. The downlink synchronization method according to claim 1, characterized in that, The step of determining the position of the first time slot header corresponding to the first synchronization period includes: Based on at least one synchronization signal block (SSB) received within the first synchronization period, the second time slot header position of the time slot where the at least one SSB is located is obtained; Based on the position of the second time slot head, the position of the first time slot head of the time slot to be adjusted is inferred.

3. The downlink synchronization method according to claim 1, characterized in that, The step of adjusting the duration of the time slot to be adjusted based on the position of the first time slot header and the delay difference of the power supply link to obtain the target time slot includes: Based on the position of the first time slot head and the overhead status of the satellite equipment, the power supply link delay difference is evenly distributed to each of the time slots to be adjusted to obtain the target time slot; The term "overhead" refers to the area above a ground gateway station during the movement of satellite equipment.

4. The downlink synchronization method according to claim 3, characterized in that, The step of distributing the power supply link delay difference equally among the time slots to be adjusted, based on the position of the first time slot head and the overhead status of the satellite equipment, to obtain the target time slot, includes: The average value of the power supply link delay difference is obtained based on the number of the first timeslot header positions; Based on the average value and the overhead position of the satellite equipment, the first time slot head position of each of the time slots to be adjusted is adjusted to obtain the target time slot.

5. The downlink synchronization method according to claim 3, characterized in that, Determining the power supply link delay difference corresponding to the first synchronization period includes: If the overpass situation indicates that the satellite equipment does not pass overpass within the first synchronization period, the power supply link delay difference corresponding to the first synchronization period is determined based on the first reception time of the first SSB and the second reception time of the second SSB received within the first synchronization period. The second SSB refers to the first SSB in the next synchronization period adjacent to the first synchronization period.

6. The downlink synchronization method according to claim 5, characterized in that, The step of distributing the power supply link delay difference equally among the time slots to be adjusted, based on the position of the first time slot head and the overhead status of the satellite equipment, to obtain the target time slot, includes: If the overhead condition indicates that the satellite equipment will not be overhead during the first synchronization period, the power supply link delay difference is evenly distributed to each of the time slots to be adjusted according to the position of the first time slot head and the direction of movement of the satellite equipment relative to the ground gateway station, so as to obtain the target time slot.

7. The downlink synchronization method according to claim 3, characterized in that, Determining the power supply link delay difference corresponding to the first synchronization period includes: When the overhead situation indicates that the satellite equipment is overhead within the first synchronization period, the first power supply link delay is obtained based on the first reception time of the first SSB received within the first synchronization period. Based on the satellite equipment's overhead position information, determine the second feeder link delay corresponding to the satellite equipment's overhead position; The third power supply link delay is determined based on the second reception time of the second SSB; the second SSB refers to the first SSB in the next synchronization period adjacent to the first synchronization period. Based on the first power supply link delay and the second power supply link delay, the power supply link delay difference before the satellite equipment passes overhead corresponding to the first synchronization period is obtained; Based on the second and third power supply link delays, the power supply link delay difference after the satellite equipment passes overhead during the first synchronization period is obtained.

8. The downlink synchronization method according to claim 7, characterized in that, The step of distributing the power supply link delay difference equally among the time slots to be adjusted, based on the position of the first time slot head and the overhead status of the satellite equipment, to obtain the target time slot, includes: When the overhead situation indicates that the satellite equipment is overhead within the first synchronization period, the power supply link delay difference before the satellite equipment is overhead is evenly distributed to each of the time slots to be adjusted before the satellite equipment is overhead, according to the position of the first time slot head and the direction of movement of the satellite equipment relative to the ground gateway station. Based on the position of the first time slot head and the direction of movement of the satellite equipment relative to the ground gateway station, the power supply link delay difference after the satellite equipment passes overhead is evenly distributed to each of the time slots to be adjusted after the satellite equipment passes overhead.

9. The downlink synchronization method according to any one of claims 1 to 8, characterized in that, Also includes: Based on the satellite equipment's overhead position information, ephemeris information, and ground gateway station position information, determine whether the satellite equipment has passed overhead during the first synchronization period.

10. A downlink synchronization device, characterized in that, include: The first determining module is used to determine the position of the first time slot head of the time slot to be adjusted corresponding to the first synchronization period and the power supply link delay difference corresponding to the first synchronization period, wherein the time slot to be adjusted is a predicted time slot. The first adjustment module is used to adjust the duration of the time slot to be adjusted according to the position of the first time slot head and the delay difference of the power supply link, so as to obtain the target time slot; The first synchronization module is used to perform downlink synchronization operations according to the target time slot.

11. A downlink synchronization device, characterized in that, include: processor; The processor is used to determine the first time slot header position of the time slot to be adjusted corresponding to the first synchronization period and the power supply link delay difference corresponding to the first synchronization period, wherein the time slot to be adjusted is a predicted time slot. Based on the position of the first time slot header and the delay difference of the power supply link, the duration of the time slot to be adjusted is adjusted to obtain the target time slot; Downlink synchronization is performed based on the target time slot.

12. A downlink synchronization device, comprising a memory, a processor, and a program stored in the memory and executable on the processor; characterized in that, When the processor executes the program, it implements the downlink synchronization method as described in any one of claims 1 to 9.

13. A readable storage medium having a program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps in the downlink synchronization method as described in any one of claims 1 to 9.

14. A computer program product, characterized in that, It includes computer instructions that, when executed by a processor, implement the steps of the downlink synchronization method as described in any one of claims 1 to 9.

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