WO2023232116A1 - 移动卫星通信系统上下行同步方法及装置 - Google Patents

移动卫星通信系统上下行同步方法及装置 Download PDF

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Publication number
WO2023232116A1
WO2023232116A1 PCT/CN2023/097855 CN2023097855W WO2023232116A1 WO 2023232116 A1 WO2023232116 A1 WO 2023232116A1 CN 2023097855 W CN2023097855 W CN 2023097855W WO 2023232116 A1 WO2023232116 A1 WO 2023232116A1
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WIPO (PCT)
Prior art keywords
synchronization
uplink
air interface
downlink
preset time
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PCT/CN2023/097855
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English (en)
French (fr)
Inventor
李自闯
王彬
孙向涛
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大唐移动通信设备有限公司
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Application filed by 大唐移动通信设备有限公司 filed Critical 大唐移动通信设备有限公司
Priority to EP23815293.8A priority Critical patent/EP4535684A1/en
Publication of WO2023232116A1 publication Critical patent/WO2023232116A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W56/00—Synchronisation arrangements
    • H04W56/001—Synchronization between nodes
    • H04W56/0015—Synchronization between nodes one node acting as a reference for the others
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/14—Relay systems
    • H04B7/15—Active relay systems
    • H04B7/185—Space-based or airborne stations; Stations for satellite systems
    • H04B7/1851—Systems using a satellite or space-based relay
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W56/00—Synchronisation arrangements
    • H04W56/004—Synchronisation arrangements compensating for timing error of reception due to propagation delay
    • H04W56/0045—Synchronisation arrangements compensating for timing error of reception due to propagation delay compensating for timing error by altering transmission time

Definitions

  • the present disclosure relates to the field of mobile communication technology, and specifically to a method and device for uplink and downlink synchronization of a mobile satellite communication system.
  • mobile satellite communication technology will be one of the key technologies of 6G communication technology.
  • the communication load of the mobile satellite communication system moves at high speed with the satellite. Therefore, the high-speed relative motion between the user terminal equipment and the satellite base station will bring about a larger Doppler frequency shift, and the larger Doppler frequency shift will Puller frequency shift will affect the frame duration change of the communication system, thereby causing a series of problems to terminal demodulation.
  • the downlink transmission and uplink reception of the base station are required to perform air interface physical frame synchronization.
  • the working scenarios of the terminal equipment of the mobile satellite communication system are different from those of the terminal equipment in the terrestrial cellular network.
  • the former needs to face the two characteristics of high-speed relative motion and large path delay of the mobile satellite communication system, making the existing terrestrial cellular network corresponding
  • the uplink and downlink synchronization scheme cannot be applied to mobile satellite communications.
  • the present disclosure aims to solve at least one aspect of the above technical problems to at least a certain extent.
  • the technical solutions provided by the embodiments of the present disclosure are as follows:
  • embodiments of the present disclosure provide a method for uplink and downlink synchronization of a mobile satellite communication system, including:
  • the inter-unit Based on the sampling point deviation value, the first UE air interface data frame received at the corresponding preset time
  • the inter-unit performs downlink synchronization pre-compensation, and performs downlink coarse synchronization based on the first UE air interface data frame after downlink synchronization pre-compensation;
  • the uplink coarse synchronization parameters are obtained based on the downlink coarse synchronization parameters and the real-time distance between the UE and the mobile satellite, and the uplink synchronization pre-compensation is performed based on the sampling point deviation value of the second UE air interface data frame to be transmitted in the corresponding preset time units, and based on The second UE air interface data frame after the uplink synchronization pre-compensation is uplink synchronized with the uplink coarse synchronization parameters.
  • downlink synchronization pre-compensation is performed on the received first air interface data frame in corresponding preset time units based on the sampling point deviation value, and based on the first downlink synchronization pre-compensation
  • the UE air interface data frame performs downlink coarse synchronization, including:
  • the synchronization header corresponding to each preset time unit of the first UE air interface data frame is determined to obtain downlink synchronization pre-compensation.
  • the first UE air interface data frame after;
  • the sampling point corresponding to the preset time unit is taken for baseband processing to obtain the synchronization signal block SSB signal;
  • the sampling point deviation value and the number of preset sampling points corresponding to the base station air interface data frame sent by the mobile satellite in each preset time unit it is determined that the first UE air interface data frame is in each preset time unit.
  • Set the synchronization header corresponding to the time unit including:
  • the last OFDM symbol from the synchronization head position in each preset time unit is increased by the number of sampling points corresponding to the sampling point deviation value, and the sampling points corresponding to other OFDM symbols and CPs are added. The number remains unchanged, and the synchronization header corresponding to each preset time unit is obtained.
  • the downlink synchronization parameters include the local frame number at the synchronization frame header position, the local time slot number, the downlink air interface frame number, the downlink air interface time slot number, and the sampling point corresponding to the downlink air interface time slot. index value;
  • the downlink air interface frame number is used as the local frame number
  • the downlink air interface time slot number is used as the local time slot number
  • the next time slot synchronization is performed based on the corresponding sampling point index value of the downlink air interface time slot.
  • obtaining the uplink coarse synchronization parameters based on the downlink coarse synchronization parameters and the real-time distance between the UE and the mobile satellite includes:
  • the second delay and the third delay Based on the first delay, the second delay and the third delay, obtain the uplink air interface frame number corresponding to the synchronization frame header position, the uplink air interface time slot frame number and the sampling point index value corresponding to the uplink air interface time slot;
  • the second UE air interface data frame to be transmitted is subjected to uplink synchronization pre-compensation in corresponding preset time units based on the sampling point deviation value, and based on the second uplink synchronization pre-compensation
  • the UE air interface data frame is uplink synchronized with the uplink coarse synchronization parameters, including:
  • the synchronization header corresponding to each preset time unit of the second UE air interface data frame is determined to obtain uplink synchronization The second UE air interface data frame after pre-compensation;
  • the uplink synchronization signal is sent to the mobile satellite, and the uplink residual timing deviation control word fed back by the mobile satellite is received, and based on the uplink The residual timing deviation control word completes upstream synchronization.
  • each of the second UE air interface data frames is determined.
  • the synchronization header corresponding to the preset time unit includes:
  • the last OFDM symbol from the synchronization head position in each preset time unit is increased by the number of sampling points corresponding to the sampling point deviation value, and the added sampling points are set to zero, and The number of sampling points corresponding to other OFDM symbols and CP Remain unchanged and obtain the synchronization header corresponding to each preset time unit;
  • the last OFDM symbol from the synchronization head position in each preset time unit is reduced by the number of sampling points corresponding to the sampling point deviation value, and the sampling points corresponding to other OFDM symbols and CPs are reduced. The number remains unchanged, and the synchronization header corresponding to each preset time unit is obtained.
  • the method further includes:
  • Phase compensation is performed on each OFDM symbol in each preset time unit of the second UE air interface data frame to be pre-compensated for uplink synchronization.
  • phase compensation is performed on each OFDM symbol in each preset time unit, including:
  • the phase value required for compensation of each subcarrier in the frequency domain of each OFDM symbol is obtained, and phase compensation is performed on the OFDM symbol in the frequency domain based on the phase value.
  • the method further includes:
  • an uplink and downlink synchronization device for a mobile satellite communication system including:
  • the sampling point deviation value acquisition module is used to obtain the sampling point deviation value between the UE and the mobile satellite within a preset time unit based on the ephemeris parameters of the mobile satellite and the coordinates of the user equipment UE;
  • the downlink coarse synchronization module is used to perform downlink synchronization pre-compensation on the received first UE air interface data frame in corresponding preset time units based on the sampling point deviation value, and based on the downlink synchronization pre-compensated first UE air interface data frame Perform downstream synchronization;
  • the uplink synchronization module is used to obtain the uplink coarse synchronization parameters based on the downlink coarse synchronization parameters and the real-time distance between the UE and the mobile satellite, and perform uplink on the second UE air interface data frame to be transmitted in the corresponding preset time units based on the sampling point deviation value. Synchronization pre-compensation, and performing uplink synchronization based on the second UE air interface data frame after uplink synchronization pre-compensation and the uplink coarse synchronization parameters.
  • the downlink coarse synchronization module is specifically used to:
  • the synchronization header corresponding to each preset time unit of the first UE air interface data frame is determined, and the downlink synchronization prediction is obtained.
  • the sampling point corresponding to the preset time unit is taken for baseband processing to obtain the synchronization signal block SSB signal;
  • the downlink coarse synchronization module is further used for:
  • the last OFDM symbol from the synchronization head position in each preset time unit is increased by the number of sampling points corresponding to the sampling point deviation value, and the sampling points corresponding to other OFDM symbols and CPs are added. The number remains unchanged, and the synchronization header corresponding to each preset time unit is obtained.
  • the downlink synchronization parameters include the local frame number at the synchronization frame header position, the local time slot number, the downlink air interface frame number, the downlink air interface time slot number, and the sampling point corresponding to the downlink air interface time slot. index value;
  • the downstream coarse synchronization module is further used for:
  • the downlink air interface frame number is used as the local frame number
  • the downlink air interface time slot number is used as the local time slot number
  • the next time slot synchronization is performed based on the corresponding sampling point index value of the downlink air interface time slot.
  • the uplink synchronization module is specifically used to:
  • the first delay corresponding to the distance is obtained, and based on The downlink coarse synchronization parameter obtains the second delay and the third delay corresponding to the downlink coarse synchronization;
  • the second delay and the third delay Based on the first delay, the second delay and the third delay, obtain the uplink air interface frame number corresponding to the synchronization frame header position, the uplink air interface time slot frame number and the sampling point index value corresponding to the uplink air interface time slot;
  • the uplink synchronization module is specifically used to:
  • the synchronization header corresponding to each preset time unit of the second UE air interface data frame is determined to obtain uplink synchronization The second UE air interface data frame after pre-compensation;
  • the uplink synchronization signal is sent to the mobile satellite, and the uplink residual timing deviation control word fed back by the mobile satellite is received, and based on the uplink The residual timing deviation control word completes upstream synchronization.
  • the uplink synchronization module is further used to:
  • the last OFDM symbol from the synchronization head position in each preset time unit is increased by the number of sampling points corresponding to the sampling point deviation value, and the added sampling points are set to zero, and Keep the number of sampling points corresponding to other OFDM symbols and CP unchanged to obtain the synchronization header corresponding to each preset time unit;
  • the last OFDM symbol from the synchronization head position in each preset time unit is reduced by the number of sampling points corresponding to the sampling point deviation value, and the sampling points corresponding to other OFDM symbols and CPs are reduced. The number remains unchanged, and the synchronization header corresponding to each preset time unit is obtained.
  • the device further includes a phase compensation module, used for:
  • OFDM symbols are phase compensated.
  • phase compensation module is specifically used for:
  • the phase value required for compensation of each subcarrier in the frequency domain of each OFDM symbol is obtained, and phase compensation is performed on the OFDM symbol in the frequency domain based on the phase value.
  • the device further includes a Doppler pre-compensation module for:
  • embodiments of the present disclosure provide an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the steps shown in the first aspect of the present disclosure are implemented.
  • Uplink and downlink synchronization method of mobile satellite communication system When the processor executes the program, the steps shown in the first aspect of the present disclosure are implemented.
  • embodiments of the present disclosure provide a computer-readable storage medium.
  • a computer program is stored on the computer-readable storage medium.
  • the computer program is executed by a processor, one or more of the embodiments of the present disclosure are implemented. method.
  • Figure 1 is a schematic flowchart of a method for uplink and downlink synchronization of a mobile satellite communication system provided by an embodiment of the present disclosure
  • Figure 2 is a schematic diagram of the downlink frame duration being compressed in an example of an embodiment of the present disclosure
  • Figure 3 is a schematic diagram of the downlink frame duration being extended in an example of the embodiment of the present disclosure
  • Figure 4 is a schematic process flow diagram of an exemplary process of the uplink and downlink synchronization scheme of the mobile satellite communication system provided by an embodiment of the present disclosure
  • Figure 5 shows a situation where the mobile satellite is getting closer to the UE in an example of the embodiment of the present disclosure.
  • the following is a schematic diagram of downlink synchronization pre-compensation for each preset time unit of the first UE air interface data frame;
  • Figure 6 is a schematic diagram of downlink synchronization pre-compensation for each preset time unit of the first UE air interface data frame when the mobile satellite is getting farther and farther away from the UE in an example of the embodiment of the present disclosure
  • Figure 7 is a schematic diagram of a downlink coarse synchronization process in an example of an embodiment of the present disclosure.
  • Figure 8 is a schematic diagram of an uplink coarse synchronization process in an example of an embodiment of the present disclosure.
  • Figure 9 is a schematic diagram of the principle of performing uplink synchronization pre-compensation on the second UE air interface data frame when the mobile satellite and the UE are getting closer and closer in an example of the embodiment of the present application;
  • Figure 10 is a schematic diagram of the principle of uplink synchronization pre-compensation for the second UE air interface data frame when the mobile satellite is getting farther and farther away from the UE in an example of the embodiment of the present application;
  • Figure 11 is a schematic diagram of uplink synchronization pre-compensation for each preset time unit of the second UE air interface data frame when the mobile satellite and the UE are getting closer and closer in an example of the embodiment of the present application;
  • Figure 12 is a schematic diagram of uplink synchronization pre-compensation for each preset time unit of the second UE air interface data frame when the mobile satellite is getting farther and farther away from the UE in an example of the embodiment of the present application;
  • Figure 13 is a structural block diagram of an uplink and downlink synchronization device for a mobile satellite communication system provided by an embodiment of the present disclosure
  • FIG. 14 is a schematic structural diagram of an electronic device provided by an embodiment of the present disclosure.
  • B corresponding to A means that B is associated with A, and B can be determined based on A.
  • determining B based on A does not mean determining B only based on A.
  • B can also be determined based on A and/or other information.
  • the solutions provided by the embodiments of the present disclosure can be executed by any electronic device, such as a terminal device or a server.
  • the server can be an independent physical server, or a server cluster or distribution composed of multiple physical servers. It can also be a cloud server that provides cloud computing services.
  • the terminal can be a smartphone, tablet, laptop, desktop computer, smart speaker, smart watch, etc., but is not limited to this.
  • the terminal and the server can be connected directly or indirectly through wired or wireless communication methods, and this disclosure is not limited here.
  • the uplink and downlink synchronization method and device of the mobile satellite communication system provided by the present disclosure are intended to solve at least one of the technical problems in the prior art.
  • FIG 1 is a schematic flow chart of an uplink and downlink synchronization method in a mobile satellite communication system provided by an embodiment of the present disclosure.
  • the execution subject of this method can be the corresponding user equipment (User Equipment, UE) in the mobile satellite communication system, as shown in Figure 1 shown, including steps S101 to S103.
  • UE User Equipment
  • Step S101 Based on the ephemeris parameters of the mobile satellite and the coordinates of the user equipment UE, obtain the sampling point deviation value between the UE and the mobile satellite within a preset time unit.
  • the preset time unit is the duration corresponding to one or more time slots.
  • the path delay between the mobile satellite and the UE changes rapidly over time.
  • the UE If the baseband sampling rate is fixed, the physical frame duration of the baseband signal received by the UE will be different from the duration of the base station side (ie, the mobile satellite side).
  • the duration of each physical frame of the first UE air interface data frame received by the UE is shorter than the frame duration on the base station side (10 ms), as shown in Figure 2.
  • the duration of each physical frame of the first UE air interface data frame received by the UE is longer than the frame duration on the base station side (10 ms), as shown in Figure 3. Because the UE baseband sampling rate remains unchanged, and the air interface frame duration may be compressed or expanded, the UE baseband processing must pre-compensate for changes in the air interface frame duration. Otherwise, as time accumulates, downlink synchronization will be lost repeatedly, affecting the UE's performance indicators. .
  • sampling point deviation value between the UE and the mobile satellite Before performing pre-compensation, it is necessary to obtain the sampling point deviation value between the UE and the mobile satellite within a preset time unit based on the ephemeris parameters of the mobile satellite and the coordinates of the user equipment UE.
  • Step S102 Perform downlink synchronization pre-compensation on the received first UE air interface data frame in corresponding preset time units based on the sampling point deviation value, and perform downlink coarse synchronization based on the first UE air interface data frame after downlink synchronization pre-compensation. Synchronize.
  • the UE before performing downlink coarse synchronization, the UE needs to perform downlink synchronization pre-compensation on the received first UE air interface data frame. Perform downlink synchronization pre-compensation on the received first UE air interface data frame in each corresponding preset time unit based on the sampling point deviation value, which can be understood as redetermining the synchronization header and sampling point of each preset time unit based on the sampling point deviation value. divide. After obtaining the first UE air interface data frame after downlink synchronization precompensation, downlink coarse synchronization is performed based on the first UE air interface data frame after downlink synchronization precompensation.
  • Doppler compensation can be performed based on the first UE air interface data frame after downlink synchronization pre-compensation, and then the Doppler compensated data frame is used for SSB front-end processing, and then SSB search is performed, and the downlink data is obtained based on the SSB search results.
  • Step S103 Obtain the uplink coarse synchronization parameters based on the downlink coarse synchronization parameters and the real-time distance between the UE and the mobile satellite, and perform uplink synchronization pre-compensation based on the sampling point deviation value of the second UE air interface data frame to be transmitted in the corresponding preset time units. , and perform uplink synchronization based on the second UE air interface data frame after uplink synchronization pre-compensation and the uplink coarse synchronization parameters.
  • the uplink coarse synchronization of the UE is different from the uplink coarse synchronization of the terrestrial cellular network system.
  • the uplink coarse synchronization can calculate the real-time distance between the mobile satellite and the UE based on the ephemeris parameters, and further calculate The path delay is then compensated for 2 times the path delay to obtain the upstream frame number and timeslot number.
  • Uplink synchronization in a mobile satellite communication system will involve two operations: uplink coarse synchronization and uplink synchronization pre-compensation for the second UE air interface data frame to be transmitted.
  • the second UE air interface data frame to be transmitted Based on the sampling point deviation value, the second UE air interface data frame to be transmitted performs uplink synchronization pre-compensation in each corresponding preset time unit, which can be understood as redetermining the synchronization header and sampling point division of each preset time unit based on the sampling point deviation value. .
  • the solution provided by this disclosure performs downlink synchronization pre-compensation and uplink synchronization pre-compensation respectively according to the sampling point deviation value corresponding to the preset time unit, so that when the local baseband sampling rate remains unchanged, the satellite terminal has less accumulated timing for baseband processing. deviation, reducing errors in frame numbers and time slot numbers, reducing the number of wireless link failures, and at the same time making the physical frame duration of the mobile satellite base station's uplink reception of multiple users almost constant, reducing the interference between uplink reception of multiple users.
  • This solution It can be well suited for uplink and downlink synchronization of mobile satellite communication systems.
  • FIG 4 is a schematic process flow diagram of an exemplary uplink and downlink synchronization scheme of a mobile satellite communication system provided by an embodiment of the present disclosure.
  • an OFDM Orthogonal The physical layer processing flow of the UE under the Frequency Division Multiplexing (orthogonal frequency division multiplexing technology) system is compared with the physical layer processing flow of the UE in the terrestrial cellular network.
  • there is an additional uplink and downlink synchronization tracking pre-compensation also known as It is uplink synchronization pre-compensation and downlink synchronization pre-compensation
  • uplink and downlink Doppler pre-compensation phase compensation 2, ephemeris calculation module, etc.
  • the channel parameters obtained in the CPU (Central Processing Unit, central processing unit) and the relevant parameters of the ephemeris calculation module are configured to the FPGA (Field Programmable Gate Array, programmable array logic) through the interface.
  • the FPGA completes the frame number in the uplink and downlink coarse synchronization. Synchronize with the time slot number, complete the frame number and time slot number synchronization in uplink and downlink synchronization tracking pre-compensation, phase compensation 2 and uplink and downlink Doppler pre-compensation.
  • phase compensation 1 is the same as the phase compensation of the terrestrial cellular network. It needs to compensate for the phase difference caused by the inconsistency between the base station and the UE's transmit and receive frequencies.
  • Phase compensation 2 is a new processing module for UE in the mobile satellite communication system. Each process in the above uplink and downlink synchronization process will be described in detail below.
  • downlink synchronization pre-compensation can be performed first, and then downlink Doppler pre-compensation can be performed, and then the compensated data can be used for SSB front-end processing. After completing the SSB search, obtain the downlink coarse synchronization parameters.
  • the data processing method is: perform downlink coarse synchronization on the first UE air interface data frame, perform downlink Doppler pre-compensation after the downlink coarse synchronization, and use the result of downlink Doppler pre-compensation for further Downlink synchronization pre-compensation and other operations.
  • the synchronization header corresponding to each preset time unit of the first UE air interface data frame is determined, and the downlink synchronization prediction is obtained.
  • the sampling point corresponding to the preset time unit is taken for baseband processing to obtain the SSB (Synchronization Signal Block, synchronization signal) signal;
  • the interface data frame performs downlink synchronization pre-compensation.
  • Downlink synchronization pre-compensation actually re-determines the number of synchronization headers and sampling points in each preset time unit (can be recorded as ⁇ T).
  • the basis for its determination is that the base station air interface data frame sent by the mobile satellite is at each preset time. The number of preset sampling points corresponding to the unit and the deviation value of the sampling points corresponding to each preset time unit.
  • downlink synchronization pre-compensation can include the following steps:
  • Step 1 According to the ephemeris parameters and the coordinates of the UE, calculate the sampling point deviation caused by the relative motion change within a ⁇ T in real time, that is, obtain the sampling point deviation value within ⁇ T.
  • Step 2 Re-determine the synchronization head corresponding to each ⁇ T based on the deviation value of the sampling point within ⁇ T.
  • the sampling point corresponding to ⁇ T is taken for baseband processing.
  • the above operations may be implemented by the downlink synchronization tracking pre-compensation module of the UE.
  • Step 3 Based on the synchronization header of each ⁇ T, maintain the downlink frame number and time slot number in real time to ensure the accuracy of the frame number and time slot number of the baseband processing data.
  • the above operations may be implemented by the downlink synchronization tracking pre-compensation module of the UE.
  • the first UE air interface data is determined based on the sampling point deviation value and the preset number of sampling points corresponding to the base station air interface data frame sent by the mobile satellite in each preset time unit.
  • the synchronization header corresponding to the frame in each preset time unit includes:
  • the CP (Cyclic Prefix) of the first orthogonal frequency division multiplexing OFDM symbol from the synchronization head position in each preset time unit is , cyclic prefix), reduce the number of sampling points corresponding to the sampling point deviation value, and keep the number of sampling points corresponding to other OFDM symbols and CP unchanged, to obtain the synchronization header corresponding to each preset time unit;
  • the last OFDM symbol from the synchronization head position in each preset time unit is increased by the number of sampling points corresponding to the sampling point deviation value, and Keeping the number of sampling points corresponding to other OFDM symbols and CP unchanged, the synchronization header corresponding to each preset time unit is obtained.
  • the baseband processing module of the UE takes the sampling point corresponding to ⁇ T according to the synchronization head position to perform baseband processing.
  • the number of time domain data sampling points taken after ephemeris information synchronization is less than the theoretical number of time domain data sampling points.
  • each OFDM symbol is processed at the baseband, and the time domain data of each OFDM symbol is obtained through CP processing.
  • the CP of the first symbol within ⁇ T has k points less, while the CPs of other OFDM symbols are of normal length.
  • the baseband processing module of the UE takes the sampling point corresponding to ⁇ T according to the synchronization head position for baseband processing.
  • the number of time domain data sampling points taken after synchronization is more than the theoretical number of time domain data sampling points.
  • each OFDM symbol is processed at the baseband, and each OFDM symbol is obtained through de-CP processing.
  • the CP and data length of each OFDM symbol are fixed, and the excess k sampling points are discarded. As shown in Figure 6, the next k sampling points of the last OFDM symbol within ⁇ T will be discarded.
  • the first UE air interface data frame after downlink synchronization pre-compensation is obtained, and the corresponding SSB signal is obtained based on the first UE air interface data frame after downlink synchronization pre-compensation.
  • the downlink coarse synchronization of the UE in the mobile satellite communication system uses the SSB signal for downlink frame number synchronization. After the baseband completes the SSB capture, it needs to report the downlink synchronization parameters to the front-end FPGA. After the FPGA obtains the synchronization parameters, it synchronizes the downlink frame number.
  • the UE of the mobile satellite communication system may not know the start of the frame before downlink coarse synchronization.
  • the UE's frame synchronization module can first randomly assume a frame header position for frame synchronization. After frame synchronization, the downlink synchronization is calculated based on the frame header position based on ephemeris. The tracking value is synchronously adjusted in real time to complete frame synchronization and time slot synchronization. The UE performs Doppler pre-compensation. Finally, the SSB signal is subjected to front-end filtering and downsampling processing, and the low sampling rate time domain data of SSB is output to the SSB capture module. And output the local frame number corresponding to the time domain data.
  • the downlink synchronization parameters include the local frame number at the synchronization frame header position, the local time slot number, the downlink air interface frame number, the downlink air interface time slot number, and the sampling point corresponding to the downlink air interface time slot. index value;
  • the downlink air interface frame number is used as the local frame number
  • the downlink air interface time slot number is used as the local time slot number
  • the next time slot synchronization is performed based on the corresponding sampling point index value of the downlink air interface time slot.
  • the SSB capture module of the UE receives the downsampled time domain data of SSB at time T0. After completing the blind detection of SSB at time T1, it calculates the SSB capture result at time T2 at time T2. Synchronization parameters and report the synchronization parameters to the FPGA.
  • the FPGA updates the frame number and time slot number at T2 time, which is the first sampling point of the N+6 frame, and re-maintains the downlink frame number synchronization.
  • the synchronization parameters at time T2 include the local frame number (local_sfn), local time slot number (local_slot), downlink air interface frame number (dl_air_sfn), downlink air interface time slot number (dl_air_slot) and downlink air interface at the sampling point at time T2.
  • the sampling point index value (dl_sym_offset) corresponding to the time slot at time T2.
  • FGPA needs to re-complete frame number synchronization, time slot number synchronization, and time slot header synchronization.
  • FPGA replaces the local frame number (local_sfn) with the downlink air interface frame number (dl_air_sfn), the local time slot number (local_slot) 0 with the air interface time slot number (dl_air_slot), and performs new time slot synchronization based on the sampling point index value (dl_sym_offset).
  • obtaining the uplink coarse synchronization parameters based on the downlink coarse synchronization parameters and the real-time distance between the UE and the mobile satellite includes:
  • the second delay and the third delay Based on the first delay, the second delay and the third delay, obtain the uplink air interface frame number corresponding to the synchronization frame header position, the uplink air interface time slot frame number and the sampling point index value corresponding to the uplink air interface time slot;
  • the UE may obtain uplink coarse synchronization parameters before performing uplink pre-compensation.
  • the uplink coarse synchronization of UE in the mobile satellite communication system is different from the uplink coarse synchronization of the UE in the terrestrial cellular network system.
  • the uplink coarse synchronization of the UE in the mobile satellite communication system requires real-time calculation of the distance between the mobile satellite and the UE based on the ephemeris parameters. , further calculate the path delay (that is, DT0, the first delay), and then compensate for 2 times the path delay to obtain the uplink frame number and timeslot number.
  • the uplink coarse synchronization process is explained using the scenario in Figure 8 as an example.
  • the T2 moment is the frame header for the initial local maintenance of the FPGA downlink, and is also the time point when the above-mentioned downlink coarse synchronization takes effect. It is also the time point when the uplink coarse synchronization takes effect.
  • the UE uses 2 times the path delay 2*DT0, and then based on the downlink air interface frame number (dl_air_sfn), downlink air interface slot number (dl_air_slot) and the sampling point index value (dl_sym_offset) corresponding to the downlink air interface slot at T2 time, Calculate DT1 (the second delay) and DT2 (the third delay), and finally calculate the uplink air interface frame number (ul_air_sfn), uplink air interface timeslot number (ul_air_slot) and The sampling point index value (ul_sym_offset) corresponding to the uplink air interface time slot at time T2.
  • the FPGA takes effect for both the downlink and uplink coarse synchronization parameters.
  • the uplink air interface frame number (ul_air_sfn) is used to replace the uplink initially maintained frame number (that is, the local frame number), and the uplink air interface time slot number (ul_air_slot) is used.
  • the uplink initial maintenance slot number i.e. local slot number
  • ul_sym_offset the sampling point index value corresponding to the uplink air interface slot number (ul_air_slot).
  • the uplink synchronization signal can be transmitted according to the maintained uplink frame number and time slot number (uplink synchronization pre-compensation is required before transmission, which will be explained in detail later), and the base station feeds back the residual transmission of the uplink synchronization signal. Timing deviation control word, and then perform more accurate uplink synchronization based on the uplink timing control word.
  • uplink coarse synchronization may include processing uplink signals according to parameters of uplink coarse synchronization (for example, maintained uplink frame number and time slot number).
  • uplink coarse synchronization may sometimes include obtaining parameters of uplink coarse synchronization.
  • the second UE air interface data frame to be transmitted is subjected to uplink synchronization pre-compensation in corresponding preset time units based on the sampling point deviation value, and based on the second uplink synchronization pre-compensation
  • the UE air interface data frame is uplink synchronized with the uplink coarse synchronization parameters, including:
  • the synchronization header corresponding to each preset time unit of the second UE air interface data frame is determined to obtain uplink synchronization The second UE air interface data frame after pre-compensation;
  • the uplink synchronization signal is sent to the mobile satellite and the uplink synchronization signal fed back by the mobile satellite is received.
  • the uplink residual timing deviation control word is generated, and uplink synchronization is completed based on the uplink residual timing deviation control word.
  • uplink synchronization after uplink coarse synchronization is completed, more precise uplink synchronization can be performed by transmitting a synchronization signal.
  • the uplink of the UE in the mobile satellite communication system also needs to calculate the uplink synchronization adjustment value based on the ephemeris in real time according to the distance change between the satellite and the UE, and perform uplink synchronization pre-compensation.
  • uplink synchronization pre-compensation the compression or expansion of the uplink frame duration caused by changes in the relative distance between the satellite and the UE is offset, so that the frame duration of the air interface signal when the uplink signal reaches the satellite base station receiver remains unchanged.
  • uplink synchronous pre-compensation and downlink synchronous pre-compensation are similar, and the operations of the two correspond to each other.
  • the uplink synchronization pre-compensation needs to expand the transmitted air interface frame to offset the air interface frame compression introduced during the uplink air interface transmission process; when the distance between the mobile satellite and the UE When getting further and further away, as shown in Figure 10, uplink synchronization pre-compensation needs to compress the transmitted air interface frame to offset the air interface frame expansion introduced by the uplink air interface transmission process.
  • uplink synchronization pre-compensation can include the following steps:
  • Step 1 According to the ephemeris parameters and the coordinates of the UE, calculate the sampling point deviation caused by the relative motion change within a ⁇ T in real time, that is, obtain the sampling point deviation value within ⁇ T, where ⁇ T has the same value as the downlink ⁇ T.
  • Step 2 Re-determine the synchronization head corresponding to each ⁇ T based on the sampling point deviation value within ⁇ T, and the baseband process transmits according to the given synchronization head position each time.
  • the above operations may be implemented by the uplink synchronization tracking pre-compensation module of the UE.
  • Step 3 Based on the synchronization header of each ⁇ T, maintain the downlink frame number and time slot number in real time to ensure the accuracy of the frame number and time slot number of the baseband processing data.
  • the above operations may be implemented by the uplink synchronization tracking pre-compensation module of the UE.
  • the second UE air interface data is determined based on the sampling point deviation value and the preset number of sampling points corresponding to the base station air interface data frame received by the mobile satellite in each preset time unit.
  • the synchronization header corresponding to each preset time unit of the frame includes:
  • the last OFDM symbol from the synchronization head position in each preset time unit is increased by the number of sampling points corresponding to the sampling point deviation value, and the added sampling points are set to zero, and The number of sampling points corresponding to other OFDM symbols and CP Remain unchanged and obtain the synchronization header corresponding to each preset time unit;
  • the last OFDM symbol from the synchronization head position in each preset time unit is reduced by the number of sampling points corresponding to the sampling point deviation value, and the sampling points corresponding to other OFDM symbols and CPs are reduced. The number remains unchanged, and the synchronization header corresponding to each preset time unit is obtained.
  • uplink synchronization pre-compensation when performing uplink synchronization pre-compensation, similar to downlink synchronization pre-compensation, it can also be divided into the following two situations:
  • the baseband processing module of the UE transmits according to the synchronization head position.
  • the baseband transmission time domain The number of data sampling points is more than the theoretical number of time domain data sampling points.
  • 0 is added to the end of the last transmitted OFDM symbol. As shown in Figure 11, the last OFDM symbol in ⁇ T is filled with 0s.
  • the baseband processing module of the UE transmits according to the synchronization head position.
  • the baseband transmits time domain data
  • the number of sampling points is less than the theoretical number of time domain data sampling points.
  • a few fewer sampling points are sent in the last transmitted OFDM symbol. As shown in Figure 12 below, the last symbol in ⁇ T is k sampling points short.
  • the method may further include:
  • Phase compensation is performed on each OFDM symbol in each preset time unit of the second UE air interface data frame after uplink synchronization pre-compensation.
  • the centralized loss or zero filling operation is performed within the preset time unit ⁇ T. Since within ⁇ T The timing deviation of each symbol is different. The deviation of ⁇ T is the result of the gradual accumulation of each symbol. Therefore, the concentrated loss or filling of zeros in the ⁇ T unit time will cause each RE (Resource Element, resource) of each symbol in the frequency domain. elements), the later symbols in ⁇ T introduce a greater frequency domain phase difference. Therefore, it is necessary to calculate the value within ⁇ T Phase compensation is performed on each symbol (ie, corresponding phase compensation 2), that is, phase compensation is performed on each RE of the frequency domain data of each symbol to avoid degradation of the demodulation performance of the channel.
  • phase compensation is performed on each symbol (ie, corresponding phase compensation 2), that is, phase compensation is performed on each RE of the frequency domain data of each symbol to avoid degradation of the demodulation performance of the channel.
  • the second UE is determined based on the sampling point deviation value and the preset number of sampling points corresponding to the base station air interface data frame received by the mobile satellite in each preset time unit.
  • the synchronization header corresponding to each preset time unit of the air interface data frame includes:
  • the last OFDM symbol from the synchronization head position in each preset time unit is increased by the number of sampling points corresponding to the sampling point deviation value, and the increased sampling points are set to zero, and other The number of sampling points corresponding to OFDM symbols and CP remains unchanged, and the synchronization header corresponding to each preset time unit is obtained;
  • the last OFDM symbol from the synchronization head position in each preset time unit is reduced by the number of sampling points corresponding to the sampling point deviation value, and the number of sampling points corresponding to other OFDM symbols and CPs remains the same. unchanged, the synchronization header corresponding to each preset time unit is obtained.
  • j represents the imaginary unit
  • pi represents the pi ratio ⁇ .
  • the physical meaning represented by this formula is that the timing deviation on the M symbols in the ⁇ T unit time is K*P/M, which averages the P points of the ⁇ T accumulated deviation.
  • the symbol timing deviation K*P/M corresponds to the frequency domain, and the range is the carrier phase value of [0:L-1].
  • the method may further include:
  • the method may further include the following operations:
  • each part of the second UE air interface data frame is Doppler pre-compensation is performed in preset time units.
  • Figure 13 is a structural block diagram of an uplink and downlink synchronization device for a mobile satellite communication system provided by an embodiment of the present disclosure.
  • the device 1300 may include: a sampling point deviation value acquisition module 1301, a downlink coarse synchronization module 1302, and an uplink coarse synchronization module.
  • the sampling point deviation value acquisition module 1301 is used to obtain the sampling point deviation value between the UE and the mobile satellite within a preset time unit based on the ephemeris parameters of the mobile satellite and the coordinates of the user equipment UE;
  • the downlink coarse synchronization module 1302 is configured to perform downlink synchronization pre-compensation on the received first UE air interface data frame in corresponding preset time units based on the sampling point deviation value, and based on the downlink synchronization pre-compensated first UE air interface data frame Perform downstream synchronization;
  • the uplink synchronization module 1303 is configured to obtain the uplink coarse synchronization parameters based on the downlink coarse synchronization parameters and the real-time distance between the UE and the mobile satellite, and perform uplink on the second UE air interface data frame to be transmitted in the corresponding preset time units based on the sampling point deviation value. Synchronization pre-compensation, and performing uplink synchronization based on the second UE air interface data frame after uplink synchronization pre-compensation and the uplink coarse synchronization parameters.
  • the downlink coarse synchronization module is specifically used to:
  • the synchronization header corresponding to each preset time unit of the first UE air interface data frame is determined, and the downlink synchronization prediction is obtained.
  • the sampling point corresponding to the preset time unit is taken for baseband processing to obtain the synchronization signal block SSB signal;
  • the downlink coarse synchronization module is further used to:
  • the last OFDM symbol from the synchronization head position in each preset time unit is increased by the number of sampling points corresponding to the sampling point deviation value, and the sampling points corresponding to other OFDM symbols and CPs are added. The number remains unchanged, and the synchronization header corresponding to each preset time unit is obtained.
  • the downlink synchronization parameters include the local frame number at the synchronization frame header position, the local time slot number, the downlink air interface frame number, the downlink air interface time slot number, and the sampling point corresponding to the downlink air interface time slot. index value;
  • the downstream coarse synchronization module is further used for:
  • the downlink air interface frame number is used as the local frame number
  • the downlink air interface time slot number is used as the local time slot number
  • the next time slot synchronization is performed based on the corresponding sampling point index value of the downlink air interface time slot.
  • the uplink synchronization module is specifically used to:
  • the second delay and the third delay Based on the first delay, the second delay and the third delay, obtain the uplink air interface frame number corresponding to the synchronization frame header position, the uplink air interface time slot frame number and the sampling point index value corresponding to the uplink air interface time slot;
  • the uplink synchronization module is specifically used to:
  • the uplink synchronization signal is sent to the mobile satellite, and the uplink residual timing deviation control word fed back by the mobile satellite is received, and based on the uplink The residual timing deviation control word completes upstream synchronization.
  • the uplink synchronization module is further used to:
  • the last OFDM symbol from the synchronization head position in each preset time unit is increased by the number of sampling points corresponding to the sampling point deviation value, and the added sampling points are set to zero, and The number of sampling points corresponding to other OFDM symbols and CP Remain unchanged and obtain the synchronization header corresponding to each preset time unit;
  • the last OFDM symbol from the synchronization head position in each preset time unit is reduced by the number of sampling points corresponding to the sampling point deviation value, and the sampling points corresponding to other OFDM symbols and CPs are reduced. The number remains unchanged, and the synchronization header corresponding to each preset time unit is obtained.
  • the device further includes a phase compensation module, used for:
  • Phase compensation is performed on each OFDM symbol in each preset time unit of the second UE air interface data frame after uplink synchronization pre-compensation.
  • phase compensation module is specifically used:
  • the phase value required for compensation of each subcarrier in the frequency domain of each OFDM symbol is obtained, and phase compensation is performed on the OFDM symbol in the frequency domain based on the phase value.
  • the device further includes a Doppler pre-compensation module for:
  • the uplink and downlink synchronization device of the mobile satellite communication system provided by the embodiment of the present disclosure can implement each process implemented in the method embodiment described above in conjunction with Figures 1 to 12. To avoid repetition, the details will not be described here.
  • the solution provided by this disclosure performs downlink synchronization pre-compensation and uplink synchronization pre-compensation respectively according to the sampling point deviation value corresponding to the preset time unit, so that when the local baseband sampling rate remains unchanged, the satellite terminal has less accumulated timing for baseband processing. deviation, reducing errors in frame numbers and time slot numbers, reducing the number of wireless link failures, and at the same time making the physical frame duration of the mobile satellite base station's uplink reception of multiple users almost constant, reducing the interference between uplink reception of multiple users.
  • This solution able to adapt well Used for uplink and downlink synchronization of mobile satellite communication systems.
  • the uplink and downlink synchronization device of the mobile satellite communication system in the embodiment of the present disclosure can execute the uplink and downlink synchronization method of the mobile satellite communication system provided by the embodiment of the present disclosure.
  • the implementation principles are similar.
  • the uplink and downlink synchronization device of the mobile satellite communication system in each embodiment of the present disclosure The actions performed by each module and unit in the synchronization device correspond to the steps in the uplink and downlink synchronization method of the mobile satellite communication system in each embodiment of the present disclosure. Details of each module of the uplink and downlink synchronization device of the mobile satellite communication system are as follows. For detailed functional description, please refer to the description in the corresponding uplink and downlink synchronization method of the mobile satellite communication system shown above, and will not be described again here.
  • the embodiment of the present disclosure also provides an electronic device, which may include but is not limited to: a processor and a memory; a memory for storing a computer program; A processor, configured to execute the uplink and downlink synchronization method of a mobile satellite communication system shown in any optional embodiment of the present disclosure by invoking a computer program.
  • the uplink and downlink synchronization method of the mobile satellite communication system performs downlink synchronization pre-compensation and uplink synchronization pre-compensation respectively according to the sampling point deviation value corresponding to the preset time unit, so that the satellite terminal samples in the local baseband
  • the rate remains unchanged, there is little accumulated timing deviation in baseband processing, reducing errors in frame numbers and time slot numbers, reducing the number of wireless link failures, and at the same time making the physical frame duration of the mobile satellite base station's uplink reception of multi-users almost fixed. It remains unchanged and reduces the interference between multiple users in uplink reception.
  • This solution can be well suited for uplink and downlink synchronization of mobile satellite communication systems.
  • an electronic device is also provided, as shown in Figure 14.
  • the electronic device 1400 shown in Figure 14 can be a server, including: a processor 1401 and a memory 1403. Among them, the processor 1401 and the memory 1403 are connected, such as through a bus 1402.
  • electronic device 1400 may also include a transceiver 1404. It should be noted that in practical applications, the number of transceivers 1404 is not limited to one, and the structure of the electronic device 1400 does not constitute a limitation on the embodiments of the present disclosure.
  • the processor 1401 may be a CPU (Central Processing Unit, central processing unit), a general-purpose processor, a DSP (Digital Signal Processor, a data signal processor), an ASIC (Application Specific Integrated Circuit, an application specific integrated circuit), or an FPGA (Field Programmable Gate Array). , field programmable gate array) or other programmable logic devices, Transistor logic devices, hardware components, or any combination thereof. It may implement or execute the various illustrative logical blocks, modules and circuits described in connection with this disclosure.
  • the processor 1401 may also be a combination that implements computing functions, such as a combination of one or more microprocessors, a combination of a DSP and a microprocessor, etc.
  • Bus 1402 may include a path that carries information between the above-mentioned components.
  • the bus 1402 may be a PCI (Peripheral Component Interconnect, Peripheral Component Interconnect Standard) bus or an EISA (Extended Industry Standard Architecture) bus, etc.
  • the bus 1402 can be divided into an address bus, a data bus, a control bus, etc. For ease of presentation, only one thick line is used in Figure 14, but it does not mean that there is only one bus or one type of bus.
  • the memory 1403 may be a ROM (Read Only Memory) or other types of static storage devices that can store static information and instructions, RAM (Random Access Memory) or other types that can store information and instructions.
  • Dynamic storage devices can also be EEPROM (Electrically Erasable Programmable Read Only Memory), CD-ROM (Compact Disc Read Only Memory) or other optical disk storage, optical disk storage (including compression Optical disc, laser disc, optical disc, digital versatile disc, Blu-ray disc, etc.), magnetic disk storage medium or other magnetic storage device, or can be used to carry or store the desired program code in the form of instructions or data structures and can be accessed by a computer Any other medium, without limitation.
  • the memory 1403 is used to store application program code for executing the disclosed solution, and is controlled by the processor 1401 for execution.
  • the processor 1401 is used to execute the application program code stored in the memory 1403 to implement the contents shown in the foregoing method embodiments.
  • electronic devices include but are not limited to: mobile phones, notebook computers, digital broadcast receivers, PDAs (personal digital assistants), PAD (tablet computers), PMP (portable multimedia players), vehicle-mounted terminals (such as vehicle-mounted navigation terminals), etc. mobile terminals such as digital TVs, desktop computers, etc.
  • PDAs personal digital assistants
  • PAD tablet computers
  • PMP portable multimedia players
  • vehicle-mounted terminals such as vehicle-mounted navigation terminals
  • mobile terminals such as digital TVs, desktop computers, etc.
  • the electronic device shown in FIG. 14 is only an example and should not impose any limitations on the functions and scope of use of the embodiments of the present disclosure.
  • the server provided by this disclosure can be an independent physical server, or a server cluster or distributed system composed of multiple physical servers. It can also provide cloud services, cloud mobile communications, cloud computing, cloud functions, cloud storage, and network services. , cloud communications, middleware services, domain name services Cloud servers for basic cloud computing services such as services, security services, CDN, and big data and artificial intelligence platforms.
  • the terminal can be a smartphone, tablet, laptop, desktop computer, smart speaker, smart watch, etc., but is not limited to this.
  • the terminal and the server can be connected directly or indirectly through wired or wireless communication methods, and this disclosure is not limited here.
  • Embodiments of the present disclosure provide a computer-readable storage medium.
  • the computer-readable storage medium stores a computer program. When run on a computer, the computer can execute the corresponding content in the foregoing method embodiments.
  • the computer-readable storage medium is a non-transitory computer-readable storage medium.
  • the computer-readable medium mentioned above in the present disclosure may be a computer-readable signal medium or a computer-readable storage medium, or any combination of the above two.
  • the computer-readable storage medium may be, for example, but is not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus or device, or any combination thereof. More specific examples of computer readable storage media may include, but are not limited to: an electrical connection having one or more wires, a portable computer disk, a hard drive, random access memory (RAM), read only memory (ROM), removable Programmd read-only memory (EPROM or flash memory), fiber optics, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination of the above.
  • a computer-readable storage medium may be any tangible medium that contains or stores a program for use by or in connection with an instruction execution system, apparatus, or device.
  • a computer-readable signal medium may include a data signal propagated in baseband or as part of a carrier wave, carrying computer-readable program code therein. Such propagated data signals may take many forms, including but not limited to electromagnetic signals, optical signals, or any of the above. Find the right combination.
  • a computer-readable signal medium may also be any computer-readable medium other than a computer-readable storage medium that can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device .
  • Program code embodied on a computer-readable medium may be transmitted using any suitable medium, including but not limited to: wire, optical cable, RF (radio frequency), etc., or any suitable combination of the above.
  • the above-mentioned computer-readable medium may be included in the above-mentioned electronic device; it may also exist independently without being assembled into the electronic device.
  • the computer-readable medium carries one or more programs.
  • the electronic device When the one or more programs are executed by the electronic device, the electronic device performs the method shown in the above embodiment.
  • a computer program product or computer program including computer instructions stored in a computer-readable storage medium.
  • the processor of the computer device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the computer device performs the uplink and downlink synchronization method of the mobile satellite communication system provided in the above various optional implementations.
  • Computer program code for performing the operations of the present disclosure may be written in one or more programming languages, including object-oriented programming languages such as Java, Smalltalk, C++, and conventional Procedural programming language—such as "C" or a similar programming language.
  • the program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server.
  • the remote computer can be connected to the user's computer through any kind of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computer (such as an Internet service provider through Internet connection).
  • LAN local area network
  • WAN wide area network
  • Internet service provider such as an Internet service provider through Internet connection
  • each block in the flowchart or block diagram may represent a module, segment, or portion of code that contains one or more logic functions that implement the specified executable instructions.
  • the functions noted in the block may occur out of the order noted in the figures. For example, two consecutive expressions The blocks may actually execute essentially in parallel, and they may sometimes execute in reverse order, depending on the functionality involved.
  • each block of the block diagram and/or flowchart illustration, and combinations of blocks in the block diagram and/or flowchart illustration can be implemented by special purpose hardware-based systems that perform the specified functions or operations. , or can be implemented using a combination of specialized hardware and computer instructions.
  • the modules involved in the embodiments of the present disclosure can be implemented in software or hardware. Among them, the name of the module does not constitute a limitation on the module itself under certain circumstances.
  • the module for obtaining the deviation value of the sampling point can also be described as "a module for obtaining the deviation value of the sampling point”.

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Abstract

本公开涉及移动通信，提供了一种移动卫星通信系统上下行同步方法及装置，方法包括：获取UE与移动卫星在预设时间单元内的采样点偏差值；基于采样点偏差值对接收到的第一UE空口数据帧进行下行同步预补偿，并基于补偿结果进行下行粗同步；基于下行粗同步参数以及UE与移动卫星的实时距离获取上行粗同步的参数，基于采样点偏差值对待发射的第二UE空口数据帧进行上行同步预补偿，并基于补偿结果和上行粗同步的参数进行上行同步。根据采样点偏差值进行上下行同步预补偿，减少基带处理累计的定时偏差，减少帧号和时隙号的错误，减少无线链路失败的次数，同时使得移动卫星基站上行接收多用户的物理帧时长固定不变，减少上行接收多用户间的干扰。

Description

移动卫星通信系统上下行同步方法及装置 技术领域
本公开涉及移动通信技术领域，具体而言，涉及一种移动卫星通信系统上下行同步方法及装置。
背景技术
对于6G(6th Generation Mobile Networks，第六代移动通信网络)通信技术而言，移动卫星通信技术将是6G通信技术的关键技术之一。移动卫星通信系统的通信载荷作为卫星的主要载荷，在随着卫星进行高速运动，因此用户终端设备与卫星基站的高速相对运动，将带来较大的多普勒频移，而较大的多普勒频移将影响通信系统的帧时长变化，进而给终端解调带来一系列问题。
作为移动卫星通信系统中的卫星通信载荷设备，和地面蜂窝网一样，要求基站的下行发射和上行接收进行空口物理帧同步。而移动卫星通信系统的终端设备与地面蜂窝网中的终端设备工作场景不同，前者需要面对移动卫星通信系统高速相对运动和较大路径时延的两大特点，使得现有的地面蜂窝网对应的上下行同步方案无法适用于移动卫星通信。
发明内容
本公开旨在至少能一定程度上解决上述的技术问题中的至少一个方面，本公开实施例所提供的技术方案如下：
第一方面，本公开实施例提供了一种移动卫星通信系统上下行同步方法，包括：
基于移动卫星的星历参数和用户设备UE的坐标，获取UE与移动卫星在预设时间单元内的采样点偏差值；
基于采样点偏差值对接收到的第一UE空口数据帧在对应的各预设时 间单元进行下行同步预补偿，并基于下行同步预补偿后的第一UE空口数据帧进行下行粗同步；
基于下行粗同步参数以及UE与移动卫星的实时距离获取上行粗同步的参数，基于采样点偏差值对待发射的第二UE空口数据帧在对应的各预设时间单元进行上行同步预补偿，并基于上行同步预补偿后的第二UE空口数据帧和上行粗同步的参数进行上行同步。
在本公开的一种可选实施例中，基于采样点偏差值对接收到的第一空口数据帧在对应的各预设时间单元进行下行同步预补偿，并基于下行同步预补偿后的第一UE空口数据帧进行下行粗同步，包括：
基于采样点偏差值以及移动卫星发送的基站空口数据帧在各预设时间单元对应的预设采样点数量，确定第一UE空口数据帧各预设时间单元对应的同步头，得到下行同步预补偿后的第一UE空口数据帧；
对每一预设时间单元按对应的同步头位置，取该预设时间单元对应的采样点进行基带处理，得到同步信号块SSB信号；
基于SSB信号中的下行同步参数进行下行粗同步。
在本公开的一种可选实施例中，基于采样点偏差值以及移动卫星发送的基站空口数据帧在各预设时间单元对应的预设采样点数量，确定第一UE空口数据帧在各预设时间单元对应的同步头，包括：
在UE与移动卫星距离递减的情况下，将每一预设时间单元中从同步头位置起的第一个正交频分复用OFDM符号的循环前缀CP减小采样点偏差值对应数量的采样点，并将其他OFDM符号以及CP对应的采样点数量保持不变，得到各预设时间单元对应的同步头；和/或
在UE与移动卫星距离递增的情况下，将每一预设时间单元中从同步头位置起最后一个OFDM符号增加采样点偏差值对应数量的采样点，并将其他OFDM符号以及CP对应的采样点数量保持不变，得到各预设时间单元对应的同步头。
在本公开的一种可选实施例中，下行同步参数包括同步帧头位置的本地帧号、本地时隙号、下行空口帧号、下行空口时隙号、以及下行空口时隙对应的采样点索引值；
基于SSB信号中的下行同步参数进行下行粗同步，包括：
将下行空口帧号作为本地帧号，将下行空口时隙号作为本地时隙号，并基于下行空口时隙对应采样点索引值进行下一次时隙同步。
在本公开的一种可选实施例中，基于下行粗同步参数以及UE与移动卫星的实时距离获取上行粗同步的参数，包括：
基于移动卫星与UE的实时距离，获取距离对应的第一时延，并基于下行粗同步参数获取下行粗同步对应的第二时延和第三时延；
基于第一时延、第二时延以及第三时延，获取在同步帧头位置对应的上行空口帧号、上行空口时隙帧号以及上行空口时隙对应的采样点索引值；
将上行空口帧号作为同步帧头位置的本地帧号，将上行空口时隙号作为同步帧头位置的本地时隙号，并基于上行空口时隙对应的采样点索引值进行下一次时隙同步。
在本公开的一种可选实施例中，基于采样点偏差值对待发射的第二UE空口数据帧在对应的各预设时间单元进行上行同步预补偿，并基于上行同步预补偿后的第二UE空口数据帧和上行粗同步的参数进行上行同步，包括：
基于采样点偏差值以及移动卫星接收到的基站空口数据帧在各预设时间单元对应的预设采样点数量，确定第二UE空口数据帧的各预设时间单元对应的同步头，得到上行同步预补偿后的第二UE空口数据帧；
基于上行粗同步的参数的上行帧号、上行时隙号以及各预设时间单元对应的同步头，向移动卫星发送上行同步信号，并接收移动卫星反馈的上行残留定时偏差控制字，并基于上行残留定时偏差控制字完成上行同步。
在本公开的一种可选实施例中，基于采样点偏差值以及移动卫星接收到的基站空口数据帧在各预设时间单元对应的预设采样点数量，确定第二UE空口数据帧的各预设时间单元对应的同步头，包括：
在UE与移动卫星距离递减的情况下，将每一预设时间单元中从同步头位置起的最后一个OFDM符号增加采样点偏差值对应数量的采样点，并将增加的采样点置零，并将其他OFDM符号以及CP对应的采样点数量 保持不变，得到各预设时间单元对应的同步头；和/或
在UE与移动卫星距离递增的情况下，将每一预设时间单元中从同步头位置起最后一个OFDM符号减少采样点偏差值对应数量的采样点，并将其他OFDM符号以及CP对应的采样点数量保持不变，得到各预设时间单元对应的同步头。
在本公开的一种可选实施例中，该方法还包括：
对下行同步预补偿后的第一UE空口数据帧的各预设时间单元中的各OFDM符号进行相位补偿；和/或
对待上行同步预补偿后的第二UE空口数据帧的各预设时间单元中的各OFDM符号进行相位补偿。
在本公开的一种可选实施例中，对各预设时间单元中的各OFDM符号进行相位补偿，包括：
基于各预设时间单元内进行上行同步预补偿的值或下行同步预补偿的值，获取各预设时间单元内每一OFDM符号对应的平均时延值；
基于平均时延值，获取每一OFDM符号在频域的每一子载波所需补偿的相位值，并基于相位值对该OFDM符号在频域进行相位补偿。
在本公开的一种可选实施例中，该方法还包括：
对下行同步预补偿后的第一UE空口数据帧的各预设时间单元进行多普勒预补偿；
对上行同步预补偿后的第二UE空口数据帧的各预设时间单元进行多普勒预补偿。
第二方面，本公开实施例提供了一种移动卫星通信系统上下行同步装置，包括：
采样点偏差值获取模块，用于基于移动卫星的星历参数和用户设备UE的坐标，获取UE与移动卫星在预设时间单元内的采样点偏差值；
下行粗同步模块，用于基于采样点偏差值对接收到的第一UE空口数据帧在对应的各预设时间单元进行下行同步预补偿，并基于下行同步预补偿后的第一UE空口数据帧进行下行同步；
上行同步模块，用于基于下行粗同步参数以及UE与移动卫星的实时距离获取上行粗同步的参数，基于采样点偏差值对待发射的第二UE空口数据帧在对应的各预设时间单元进行上行同步预补偿，并基于上行同步预补偿后的第二UE空口数据帧和上行粗同步的参数进行上行同步。
在本公开的一种可选实施例中，下行粗同步模块具体用于：
基于采样点偏差值、以及移动卫星发送的基站空口数据帧在各预设时间单元对应的预设采样点数量，确定第一UE空口数据帧各预设时间单元对应的同步头，得到下行同步预补偿后的第一UE空口数据帧；
对每一预设时间单元按对应的同步头位置，取该预设时间单元对应的采样点进行基带处理，得到同步信号块SSB信号；
基于SSB信号中的下行同步参数进行下行粗同步。
在本公开的一种可选实施例中，下行粗同步模块进一步用于：
在UE与移动卫星距离递减的情况下，将每一预设时间单元中从同步头位置起的第一个正交频分复用OFDM符号的循环前缀CP减小采样点偏差值对应数量的采样点，并将其他OFDM符号以及CP对应的采样点数量保持不变，得到各预设时间单元对应的同步头；
在UE与移动卫星距离递增的情况下，将每一预设时间单元中从同步头位置起最后一个OFDM符号增加采样点偏差值对应数量的采样点，并将其他OFDM符号以及CP对应的采样点数量保持不变，得到各预设时间单元对应的同步头。
在本公开的一种可选实施例中，下行同步参数包括同步帧头位置的本地帧号、本地时隙号、下行空口帧号、下行空口时隙号、以及下行空口时隙对应的采样点索引值；
下行粗同步模块进一步用于：
将下行空口帧号作为本地帧号，将下行空口时隙号作为本地时隙号，并基于下行空口时隙对应采样点索引值进行下一次时隙同步。
在本公开的一种可选实施例中，在本公开的一种可选实施例中，上行同步模块具体用于：
基于移动卫星与UE的实时距离，获取距离对应的第一时延，并基于 下行粗同步参数获取下行粗同步对应的第二时延和第三时延；
基于第一时延、第二时延以及第三时延，获取在同步帧头位置对应的上行空口帧号、上行空口时隙帧号以及上行空口时隙对应的采样点索引值；
将上行空口帧号作为同步帧头位置的本地帧号，将上行空口时隙号作为同步帧头位置的本地时隙号，并基于上行空口时隙对应的采样点索引值进行下一次时隙同步。
在本公开的一种可选实施例中，在本公开的一种可选实施例中，上行同步模块具体用于：
基于采样点偏差值以及移动卫星接收到的基站空口数据帧在各预设时间单元对应的预设采样点数量，确定第二UE空口数据帧的各预设时间单元对应的同步头，得到上行同步预补偿后的第二UE空口数据帧；
基于上行粗同步的参数的上行帧号、上行时隙号以及各预设时间单元对应的同步头，向移动卫星发送上行同步信号，并接收移动卫星反馈的上行残留定时偏差控制字，并基于上行残留定时偏差控制字完成上行同步。
在本公开的一种可选实施例中，在本公开的一种可选实施例中，上行同步模块进一步用于：
在UE与移动卫星距离递减的情况下，将每一预设时间单元中从同步头位置起的最后一个OFDM符号增加采样点偏差值对应数量的采样点，并将增加的采样点置零，并将其他OFDM符号以及CP对应的采样点数量保持不变，得到各预设时间单元对应的同步头；和/或
在UE与移动卫星距离递增的情况下，将每一预设时间单元中从同步头位置起最后一个OFDM符号减少采样点偏差值对应数量的采样点，并将其他OFDM符号以及CP对应的采样点数量保持不变，得到各预设时间单元对应的同步头。
在本公开的一种可选实施例中，该装置还包括相位补偿模块，用于：
对下行同步预补偿后的第一UE空口数据帧的各预设时间单元中的各OFDM符号进行相位补偿；和/或
对上行同步预补偿后的第二UE空口数据帧的各预设时间单元中的各 OFDM符号进行相位补偿。
在本公开的一种可选实施例中，相位补偿模块具体用于：
基于各预设时间单元内进行上行同步预补偿的值或下行同步预补偿的值，获取各预设时间单元内每一OFDM符号对应的平均时延值；
基于平均时延值，获取每一OFDM符号在频域的每一子载波所需补偿的相位值，并基于相位值对该OFDM符号在频域进行相位补偿。
在本公开的一种可选实施例中，该装置还包括多普勒预补偿模块，用于：
对下行同步预补偿后的第一UE空口数据帧的各预设时间单元进行多普勒预补偿；
对上行同步预补偿后的第二UE空口数据帧的各预设时间单元进行多普勒预补偿。
第三方面，本公开实施例提供了一种电子设备，包括存储器、处理器及存储在存储器上并可在处理器上运行的计算机程序，处理器执行程序时实现本公开第一方面所示的移动卫星通信系统上下行同步方法。
第四方面，本公开实施例提供了一种计算机可读存储介质，该计算机可读存储介质上存储有计算机程序，该计算机程序被处理器执行时实现如本公开实施例中一个或多个的方法。
附图说明
为了更清楚地说明本公开实施例中的技术方案，下面将对本公开实施例描述中所需要使用的附图作简单地介绍。
图1为本公开实施例提供的一种移动卫星通信系统上下行同步方法的流程示意图；
图2为本公开实施例的一个示例中下行时帧时长被压缩的示意图；
图3为本公开实施例的一个示例中下行时帧时长被扩展的示意图；
图4为本公开实施例提供的移动卫星通信系统上下行同步方案的一个示例性处理流程示意图；
图5为本公开实施例的一个示例中在移动卫星与UE越来越近的情况 下对第一UE空口数据帧各预设时间单元进行下行同步预补偿的示意图；
图6为本公开实施例的一个示例中在移动卫星与UE越来越远的情况下对第一UE空口数据帧的各预设时间单元进行下行同步预补偿的示意图；
图7为本公开实施例的一个示例中下行粗同步过程的示意图；
图8为本公开实施例的一个示例中上行粗同步过程的示意图；
图9为本申请实施例的一个示例中在移动卫星与UE越来越近的情况下对第二UE空口数据帧进行上行同步预补偿的原理示意图；
图10为本申请实施例的一个示例中在移动卫星与UE越来越远的情况下对第二UE空口数据帧进行上行同步预补偿的原理示意图；
图11为本申请实施例的一个示例中在移动卫星与UE越来越近的情况下对第二UE空口数据帧各预设时间单元进行上行同步预补偿的示意图；
图12为本申请实施例的一个示例中在移动卫星与UE越来越远的情况下对第二UE空口数据帧的各预设时间单元进行上行同步预补偿的示意图；
图13为本公开实施例提供的一种移动卫星通信系统上下行同步装置的结构框图；
图14为本公开实施例提供的一种电子设备的结构示意图。
具体实施方式
下面详细描述本公开的实施例，实施例的示例在附图中示出，其中自始至终相同或类似的标号表示相同或类似的元件或具有相同或类似功能的元件。下面通过参考附图描述的实施例是示例性的，仅用于解释本公开，而不能解释为对本公开的限制。
本技术领域技术人员可以理解，除非特意声明，这里使用的单数形式“一”、“一个”、“”和“该”也可包括复数形式。应该进一步理解的是，本公开的说明书中使用的措辞“包括”是指存在特征、整数、步骤、操作、元件和/或组件，但是并不排除存在或添加一个或多个其他特征、整数、步骤、操作、元件、组件和/或它们的组合。应该理解，当我们称 元件被“连接”或“耦接”到另一元件时，它可以直接连接或耦接到其他元件，或者也可以存在中间元件。此外，这里使用的“连接”或“耦接”可以包括无线连接或无线耦接。
在本公开的各种实施例中，应理解，下述各过程的序号的大小并不意味着执行顺序的先后，各过程的执行顺序应以其功能和内在逻辑确定，而不应对本公开实施例的实施过程构成任何限定。说明书和权利要求书中的术语“第一”、“第二”等是用于区别类似的对象，而不用于描述特定的顺序或先后次序。应该理解这样使用的数据在适当情况下可以互换，以便本公开的实施例能够以除了在这里图示或描述的那些以外的顺序实施。此外，说明书以及权利要求中“和/或”表示所连接对象的至少其中之一，包括一个或更多个相关联的列出项的全部或任一单元和全部组合，字符“/”，一般表示前后关联对象是一种“或”的关系。
在本公开所提供的实施例中，应理解，“与A相应的B”表示B与A相关联，根据A可以确定B。但还应理解，根据A确定B并不意味着仅仅根据A确定B，还可以根据A和/或其它信息确定B。
此外，本领域技术人员可以理解，除非另外定义，这里使用的所有术语(包括技术术语和科学术语)，具有与本发明所属领域中的普通技术人员的一般理解相同的意义。还应该理解的是，诸如通用字典中定义的那些术语，应该被理解为具有与现有技术的上下文中的意义一致的意义，并且除非像这里一样被特定定义，否则不会用理想化或过于正式的含义来解释。
本公开实施例所提供的方案可以由任一电子设备执行，如可以是终端设备，也可以是服务器，其中，服务器可以是独立的物理服务器，也可以是多个物理服务器构成的服务器集群或者分布式系统，还可以是提供云计算服务的云服务器。终端可以是智能手机、平板电脑、笔记本电脑、台式计算机、智能音箱、智能手表等，但并不局限于此。终端以及服务器可以通过有线或无线通信方式进行直接或间接地连接，本公开在此不做限制。对于现有技术中所存在的技术问题，本公开提供的移动卫星通信系统上下行同步方法及装置，旨在解决现有技术的技术问题中的至少一项。
下面以具体实施例对本公开的技术方案以及本公开的技术方案如何解决上述技术问题进行详细说明。下面这几个具体的实施例可以相互结合，对于相同或相似的概念或过程可能在某些实施例中不再赘述。下面将结合附图，对本公开的实施例进行描述。
图1为本公开实施例提供的一种移动卫星通信系统上下行同步方法的流程示意图，该方法的执行主体可以是移动卫星通信系统中对应的用户设备(User Equipment，UE)，如图1所示，包括步骤S101到S103。
步骤S101，基于移动卫星的星历参数和用户设备UE的坐标，获取UE与移动卫星在预设时间单元内的采样点偏差值。
其中，预设时间单元为一个或多个时隙对应的时长。
具体地，由于移动卫星(可以理解为(移动卫星通信系统中的基站))与UE之间的高速的相对运动，移动卫星与UE之间的路径时延随着时间在快速变化，如果UE的基带采样率固定不变，则会导致UE接收的基带信号的物理帧时长与基站侧(即移动卫星侧)的时长不等。当移动卫星与UE的距离越来越近时，UE接收到的第一UE空口数据帧的每个物理帧时长小于基站侧的帧时长(10ms)，如图2所示。当移动卫星与UE的距离越来越远时，UE接收到的第一UE空口数据帧的每个物理帧时长大于基站侧的帧时长(10ms)，如图3所示。因为UE基带采样率不变，而空口的帧时长可能会被压缩或被扩展，UE基带处理要预补偿空口帧时长的变化，否则随着时间累积，下行同步将反复丢失，影响UE的性能指标。
同理，在上行同步过程中，也需要预补偿空口帧时长的变化，抵消上行空口信号由于移动卫星和UE相对距离变化而引入的上行帧时长的压缩或扩展，使得上行信号到达移动卫星基站接收机的空口信号的帧时长不变。
在进行预补偿前，需要基于移动卫星的星历参数和用户设备UE的坐标，获取UE与移动卫星在预设时间单元内的采样点偏差值。
步骤S102，基于采样点偏差值，对接收到的第一UE空口数据帧在对应的各预设时间单元进行下行同步预补偿，并基于下行同步预补偿后的第一UE空口数据帧进行下行粗同步。
具体地，UE在进行下行粗同步之前，需要先对接收到的第一UE空口数据帧进行下行同步预补偿。基于采样点偏差值对接收到的第一UE空口数据帧在对应的各预设时间单元进行下行同步预补偿，可以理解为基于采样点偏差值重新确定各预设时间单元的同步头和采样点划分。在得到下行同步预补偿后的第一UE空口数据帧后，基于该下行同步预补偿后的第一UE空口数据帧进行下行粗同步。例如，可基于下行同步预补偿后的第一UE空口数据帧进行多普勒补偿，再将多普勒补偿后的数据帧用于SSB前端处理，之后进行SSB搜索，根据SSB搜索结果，获取下行粗同步参数，从而进行下行粗同步。
步骤S103，基于下行粗同步参数以及UE与移动卫星的实时距离获取上行粗同步的参数，基于采样点偏差值对待发射的第二UE空口数据帧在对应的各预设时间单元进行上行同步预补偿，并基于上行同步预补偿后的第二UE空口数据帧和上行粗同步的参数进行上行同步。
具体地，移动卫星通信系统中，UE进行上行粗同步与地面蜂窝网系统的上行粗同步不同，本公开实施例中上行粗同步可根据星历参数计算出移动卫星与UE的实时距离，进一步计算路径时延，然后补偿2倍的路径时延得到上行的帧号和时隙号。移动卫星通信系统中的上行同步将涉及上行粗同步和对待发射的第二UE空口数据帧进行上行同步预补偿两种操作。基于采样点偏差值对待发射的第二UE空口数据帧在对应的各预设时间单元进行上行同步预补偿，可以理解为基于采样点偏差值重新确定各预设时间单元的同步头和采样点划分。
本公开提供的方案，分别根据预设时间单元对应的采样点偏差值进行下行同步预补偿和上行同步预补偿，使得卫星终端在本地基带采样率不变的情况下，基带处理少有累计的定时偏差，减少出现帧号和时隙号的错误，减少无线链路失败的次数，同时使得移动卫星基站上行接收多用户的物理帧时长几乎固定不变，减少上行接收多用户间的干扰，该方案能够很好适用于移动卫星通信系统的上下行同步。
图4为本公开实施例提供的移动卫星通信系统上下行同步方案的一个示例性处理流程示意图，如图4所示，给出了OFDM(Orthogonal  Frequency Division Multiplexing，正交频分复用技术)体制下UE的物理层处理流程，相较于地面蜂窝网络的UE的物理层处理流程，该示例中多出了上下行同步跟踪预补偿(也称为上行同步预补偿和下行同步预补偿)、上下行多普勒预补偿、相位补偿2、星历计算模块等。CPU(Central Processing Unit，中央处理器)中获取的信道参数以及星历计算模块的相关参数通过接口配置给FPGA(Field Programmable Gate Array，可编程阵列逻辑)，FPGA完成上下行粗同步中的帧号和时隙号同步，完成上下行同步跟踪预补偿中的帧号和时隙号同步以及相位补偿2和上下行的多普勒预补偿。其中，相位补偿1和地面蜂窝网的相位补偿一样，需要补偿基站和UE收发频点不一致引起的相位差。相位补偿2是移动卫星通信系统中的UE新增的处理模块。下面将对上述上下行同步过程中的各个流程进行详细说明。
在本公开的一种可选实施例中，在一次通信过程中，可首先进行下行同步预补偿，之后进行下行多普勒预补偿，再将补偿后的数据用于SSB前端处理。在完成SSB搜索后，获取下行粗同步参数。
在随后的通信过程中，数据处理方式为：对第一UE空口数据帧进行下行粗同步，在下行粗同步之后进行下行多普勒预补偿，并将下行多普勒预补偿的结果用于进一步的下行同步预补偿等操作。
基于采样点偏差值对接收到的第一空口数据帧在对应的各预设时间单元进行下行同步预补偿，并基于下行同步预补偿后的第一UE空口数据帧进行下行粗同步，包括：
基于采样点偏差值、以及移动卫星发送的基站空口数据帧在各预设时间单元对应的预设采样点数量，确定第一UE空口数据帧各预设时间单元对应的同步头，得到下行同步预补偿后的第一UE空口数据帧；
对每一预设时间单元按对应的同步头位置，取该预设时间单元对应的采样点进行基带处理，得到块SSB(Synchronization Signal Block，同步信号)信号；以及
基于SSB信号中的下行同步参数进行下行粗同步。
具体地，UE在进行下行粗同步之前，首先要对接收到的第一UE空 口数据帧进行下行同步预补偿。下行同步预补偿实际上对每一预设时间单元(可记为ΔT)内的同步头和采样点数量进行重新确定，其确定的根据即为移动卫星发送的基站空口数据帧在各预设时间单元对应的预设采样点数量和每一预设时间单元对应的采样点偏差值。在得到下行同步预补偿后的第一UE空口数据帧后，对重新确定的同步头和对应的采样点进行基带处理，得到SSB信号，进而基于SSB信号进行下行粗同步。
具体来说，下行同步预补偿可以包括以下几个步骤：
步骤1：根据星历参数以及UE的坐标，实时计算一个ΔT内由于相对运动变化引起的采样点偏差，即得到ΔT内的采样点偏差值。
步骤2：基于ΔT内的采样点偏差值重新确定出每个ΔT对应的同步头，每次按照给的同步头位置，取ΔT对应的采样点进行基带处理。在一些实施例中，上述操作可以由UE的下行同步跟踪预补偿模块实现。
步骤3：根据每个ΔT的同步头，实时维护下行的帧号和时隙号，保证基带处理数据的帧号和时隙号的准确性。在一些实施例中，上述操作可以由UE的下行同步跟踪预补偿模块实现。
进一步地，在本公开的一种可选实施例中，基于采样点偏差值、以及移动卫星发送的基站空口数据帧在各预设时间单元对应的预设采样点数量，确定第一UE空口数据帧在各预设时间单元对应的同步头，包括：
在UE与移动卫星距离递减(即二者越来越近)的情况下，将每一预设时间单元中从同步头位置起的第一个正交频分复用OFDM符号的CP(Cyclic Prefix，循环前缀)减小采样点偏差值对应数量的采样点，并将其他OFDM符号以及CP对应的采样点数量保持不变，得到各预设时间单元对应的同步头；
在UE与移动卫星距离递增(即二者距离越来越远)的情况下，将每一预设时间单元中从同步头位置起最后一个OFDM符号增加采样点偏差值对应数量的采样点，并将其他OFDM符号以及CP对应的采样点数量保持不变，得到各预设时间单元对应的同步头。
具体地，在进行下行同步预补偿时，可以分为以下两种情形：
其一，UE的基带处理模块按照同步头位置取ΔT对应的采样点进行基 带处理，在移动卫星与UE越来越近的场景下(即UE与移动卫星距离递减的情形)，经过星历信息同步后取的时域数据采样点数比理论的时域数据采样点数少，此时根据OFDM体制移动卫星通信系统的帧结构特点，在基带对每个OFDM符号处理，通过去CP处理得到每个OFDM符号的时域数据。如图5所示，ΔT内第1个符号的CP少了k个点，而其它OFDM符号的CP是正常长度。
其二，UE的基带处理模块按照同步头位置取ΔT对应的采样点进行基带处理，在移动卫星与UE越来越远的场景下(即UE与移动卫星距离递增的情形)，经过星历信息同步后取的时域数据采样点数比理论的时域数据采样点数多，此时根据OFDM体制移动卫星通信系统的帧结构特点，在基带对每个OFDM符号处理，通过去CP处理得到每个OFDM符号的时域数据，每个OFDM符号的CP和数据长度固定，把多的k个采样点给丢弃掉。如图6所示，ΔT内最后一个OFDM符号的后面k个采样点将被丢弃。
在完成上述下行同步预补偿后，得到下行同步预补偿后的第一UE空口数据帧，基于该下行同步预补偿后的第一UE空口数据帧得到对应的SSB信号。移动卫星通信系统的UE的下行粗同步，利用SSB信号进行下行帧号同步，基带完成SSB的捕获后，需要给前端FPGA上报下行同步参数，FPGA得到同步参数后，同步下行帧号。
移动卫星通信系统的UE在下行粗同步之前可能并不知道帧起始，UE的帧同步模块可先随机假定一个帧头位置进行帧同步，帧同步后按照帧头位置根据星历计算的下行同步跟踪值实时进行同步调整，完成帧同步和时隙同步，UE进行多普勒预补偿，最后对SSB信号进行前端的滤波降采样处理，给SSB捕获模块输出SSB的低采样率的时域数据，并输出对应时域数据的本地帧号。
在本公开的一种可选实施例中，下行同步参数包括同步帧头位置的本地帧号、本地时隙号、下行空口帧号、下行空口时隙号、以及下行空口时隙对应的采样点索引值；
基于SSB信号中的下行同步参数进行下行粗同步，包括：
将下行空口帧号作为本地帧号，将下行空口时隙号作为本地时隙号，并基于下行空口时隙对应采样点索引值进行下一次时隙同步。
具体地，如图7所示，UE的SSB捕获模块在T0时刻收到降采样后SSB的时域数据，在T1时刻完成SSB的盲检后，在T1时刻根据SSB捕获的结果计算T2时刻的同步参数，并给FPGA上报该同步参数，FPGA在T2时刻，也就是N+6帧的第1个采样点时刻更新帧号和时隙号，重新维护下行帧号同步。
具体来说，T2时刻的同步参数包括，T2时刻采样点的本地帧号(local_sfn)、本地时隙号(local_slot)、下行空口帧号(dl_air_sfn)、下行空口时隙号(dl_air_slot)和下行空口时隙在T2时刻对应的采样点索引值(dl_sym_offset)。FGPA在T2时刻，需要重新完成帧号同步、时隙号同步，时隙头同步。FPGA用下行空口帧号(dl_air_sfn)替换本地帧号(local_sfn)，本地时隙号(local_slot)0用空口时隙号(dl_air_slot)替换，根据采样点索引值(dl_sym_offset)进行新的时隙同步。
在本公开的一种可选实施例中，基于下行粗同步参数以及UE与移动卫星的实时距离获取上行粗同步的参数，包括：
基于移动卫星与UE的实时距离，获取距离对应的第一时延，并基于下行粗同步参数获取下行粗同步对应的第二时延和第三时延；
基于第一时延、第二时延以及第三时延，获取在同步帧头位置对应的上行空口帧号、上行空口时隙帧号以及上行空口时隙对应的采样点索引值；
将上行空口帧号作为同步帧头位置的本地帧号，将上行空口时隙号作为同步帧头位置的本地时隙号，并基于上行空口时隙对应的采样点索引值进行下一次时隙同步。
具体地，UE可在进行上行预补偿之前，获取上行粗同步的参数。移动卫星通信系统中的UE的上行粗同步与地面蜂窝网系统中的UE的上行粗同步不同，移动卫星通信系统中的UE的上行粗同步需要根据星历参数实时计算出移动卫星与UE的距离，进一步计算路径时延(即DT0，第一时延)，然后补偿2倍的路径时延得到上行的帧号和时隙号。
具体来说，上行粗同步过程以图8的场景为例进行说明，T2时刻是FPGA下行本地初始维护的帧头，也是上述下行粗同步生效的时间点，同时也是上行粗同步生效的时间点，UE根据2倍的路径时延2*DT0，再根据T2时刻下行空口帧号(dl_air_sfn)、下行空口时隙号(dl_air_slot)和下行空口时隙在T2时刻对应的采样点索引值(dl_sym_offset)，计算出DT1(即第二时延)和DT2(第三时延)，最后根据2*DT0+DT1+DT2计算出T2时刻的上行空口帧号(ul_air_sfn)、上行空口时隙号(ul_air_slot)和上行空口时隙在T2时刻对应的采样点索引值(ul_sym_offset)。
FPGA在T2时刻，同时生效下行和上行的粗同步参数，上行在T2时刻，用上行空口帧号(ul_air_sfn)替换上行初始维护的帧号(即本地帧号)，用上行空口时隙号(ul_air_slot)替换上行初始维护的时隙号(即本地时隙号)0，根据上行空口时隙号(ul_air_slot)对应的采样点索引值(ul_sym_offset)，同步下个时隙的时隙头。
获取上行粗同步的参数后，可根据维护的上行帧号和时隙号发射上行同步信号(在发射前需要进行上行同步预补偿，后文将详细说明)，基站反馈上行同步信号的发射的残留定时偏差控制字，再根据上行定时控制字做更精确的上行同步。
例如，参见图4，一些实施例中上行粗同步可以包括根据上行粗同步的参数(例如，维护的上行帧号和时隙号)，对上行信号进行处理。而在一些实施例中，上行粗同步有时也可包括获取上行粗同步的参数。
在本公开的一种可选实施例中，基于采样点偏差值对待发射的第二UE空口数据帧在对应的各预设时间单元进行上行同步预补偿，并基于上行同步预补偿后的第二UE空口数据帧和上行粗同步的参数进行上行同步，包括：
基于采样点偏差值以及移动卫星接收到的基站空口数据帧在各预设时间单元对应的预设采样点数量，确定第二UE空口数据帧的各预设时间单元对应的同步头，得到上行同步预补偿后的第二UE空口数据帧；
基于上行粗同步的参数的上行帧号、上行时隙号以及各预设时间单元对应的同步头，向移动卫星发送上行同步信号，并接收移动卫星反馈的上 行残留定时偏差控制字，并基于上行残留定时偏差控制字完成上行同步。
具体地，在完成上行粗同步后，即可通过发射同步信号进行更精确的上行同步。移动卫星通信系统的UE的上行链路也需要根据卫星与UE的距离变化，实时根据星历计算上行同步调整值，并进行上行同步预补偿。通过上行同步预补偿，抵消上行空口信号由于卫星和UE相对距离变化而引入的上行帧时长的压缩或扩展，使得上行信号到达卫星基站接收机的空口信号的帧时长不变。
从原理上来说，上行同步预补偿与下行同步预补偿的原理是类似的，二者操作是相互对应的。如图9所示，当移动卫星与UE的距离越来越近时，上行同步预补偿需要把发射的空口帧扩展，以抵消上行空口发射过程引入的空口帧压缩；当移动卫星与UE的距离越来越远时，如图10所示，上行同步预补偿需要把发射的空口帧压缩，以抵消上行空口发射过程引入的空口帧扩展。
具体来说，上行同步预补偿可以包括以下几个步骤：
步骤1：根据星历参数以及UE的坐标，实时计算一个ΔT内由于相对运动变化引起的采样点偏差，即得到ΔT内的采样点偏差值，此处ΔT与下行ΔT取值相同。
步骤2：基于ΔT内的采样点偏差值重新确定出每个ΔT对应的同步头，基带处理每次按照给的同步头位置进行发射。在一些实施例中，上述操作可由UE的上行同步跟踪预补偿模块实现。
步骤3：根据每个ΔT的同步头，实时维护下行的帧号和时隙号，保证基带处理数据的帧号和时隙号的准确性。在一些实施例中，上述操作可由UE的上行同步跟踪预补偿模块实现。
进一步地，在本公开的一种可选实施例中，基于采样点偏差值以及移动卫星接收到的基站空口数据帧在各预设时间单元对应的预设采样点数量，确定第二UE空口数据帧的各预设时间单元对应的同步头，包括：
在UE与移动卫星距离递减的情况下，将每一预设时间单元中从同步头位置起的最后一个OFDM符号增加采样点偏差值对应数量的采样点，并将增加的采样点置零，并将其他OFDM符号以及CP对应的采样点数量 保持不变，得到各预设时间单元对应的同步头；
在UE与移动卫星距离递增的情况下，将每一预设时间单元中从同步头位置起最后一个OFDM符号减少采样点偏差值对应数量的采样点，并将其他OFDM符号以及CP对应的采样点数量保持不变，得到各预设时间单元对应的同步头。
具体地，在进行上行同步预补偿时，与下行同步预补偿类似，也可以分为以下两种情形：
其一，UE的基带处理模块按照同步头位置进行发射，在移动卫星与UE越来越近的场景下(即UE与移动卫星距离递减的情形)，经过上行同步预补偿后，基带发射时域数据采样点数比理论的时域数据采样点数多，此时根据OFDM体制移动卫星通信系统的帧结构特点，在最后一个发射OFDM符号末尾补0。如图11所示，ΔT内最后1个OFDM符号补0。
其二，UE的基带处理模块按照同步头位置进行发射，在移动卫星与UE越来越远的场景(即UE与移动卫星距离递增的情形)，经过上行同步预补偿后，基带发射时域数据采样点数比理论的时域数据采样点数少，此时根据OFDM体制移动卫星通信系统的帧结构特点，在最后一个发射OFDM符号少发几个采样点。如下图12所示，ΔT内最后1个符号少发k个采样点。
在本公开的一种可选实施例中，该方法还可以包括：
对下行同步预补偿后的第一UE空口数据帧的各预设时间单元中的各OFDM符号进行相位补偿；和/或
对上行同步预补偿后的第二UE空口数据帧的各预设时间单元中的各OFDM符号进行相位补偿。
具体地，由于移动卫星通信系统的UE的上下行都需要同步预补偿，根据前述上下行同步预补偿的方案，都是在预设时间单元ΔT内进行集中丢数或补0操作，由于ΔT内每个符号的定时偏差不同，ΔT的偏差是每个符号逐渐累计出来的结果，因此在ΔT单位时间内集中丢数或补0会导致每个符号在频域的每个RE(Resource Element，资源元素)上引入不同的相位差，ΔT内越靠后的符号引入的频域相位差越大。因此需要对ΔT内的 每个符号进行相位补偿(即对应的相位补偿2)，即对每个符号的频域数据的每个RE进行相位补偿，从而避免信道的解调性能下降。
具体来说，在本公开的一种可选实施例中，基于采样点偏差值、以及移动卫星接收到的基站空口数据帧在各预设时间单元对应的预设采样点数量，确定第二UE空口数据帧的各预设时间单元对应的同步头，包括：
对于UE与移动卫星距离递减的情形，令每一预设时间单元中至同步头位置起的最后一个OFDM符号增加采样点偏差值对应数量的采样点，并将增加的采样点置零，且其他OFDM符号以及CP对应的采样点数量保持不变，得到各预设时间单元对应的同步头；
对于UE与移动卫星距离递增的情形，令每一预设时间单元中至同步头位置起最后一个OFDM符号减少采样点偏差值对应数量的采样点，且其他OFDM符号以及CP对应的采样点数量保持不变，得到各预设时间单元对应的同步头。
假设ΔT内有M个符号，每个符号做FFT的长度为L，ΔT的定时偏差为P个采样点(有正负)。那么，ΔT内第K(K的范围1～M)个符号，做完L点FFT后的频域数据需要补偿的系数公式为：
exp(-j*2*pi*K*P*[0：L-1]/(M*L))
其中，j表示虚数单位，pi表示圆周率π，该公式代表的物理意义是，把ΔT累加偏差的P个点平均到ΔT单位时间内的M个符号上的定时偏差是K*P/M，该符号的定时偏差K*P/M对应到频域上，范围是[0:L-1]的载波相位值。
在本公开的一种可选实施例中，该方法还可以包括：
对下行同步预补偿后的第一UE空口数据帧的各预设时间单元进行多普勒预补偿；和/或
对上行同步预补偿后的第二UE空口数据帧的各预设时间单元进行多普勒预补偿。在本公开的另一种可选实施例中，该方法还可包括以下操作：
在下行粗同步之后，下行同步预补偿前，对第一UE空口数据帧的各预设时间单元进行多普勒预补偿；和/或
在上行同步预补偿之后，上行粗同步前，对第二UE空口数据帧的各 预设时间单元进行多普勒预补偿。
图13为本公开实施例提供了一种移动卫星通信系统上下行同步装置的结构框图，如图13所示，该装置1300可以包括：采样点偏差值获取模块1301、下行粗同步模块1302以及上行同步模块1303。其中：
采样点偏差值获取模块1301用于基于移动卫星的星历参数和用户设备UE的坐标，获取UE与移动卫星在预设时间单元内的采样点偏差值；
下行粗同步模块1302用于基于采样点偏差值对接收到的第一UE空口数据帧在对应的各预设时间单元进行下行同步预补偿，并基于下行同步预补偿后的第一UE空口数据帧进行下行同步；
上行同步模块1303用于基于下行粗同步参数以及UE与移动卫星的实时距离获取上行粗同步的参数，基于采样点偏差值对待发射的第二UE空口数据帧在对应的各预设时间单元进行上行同步预补偿，并基于上行同步预补偿后的第二UE空口数据帧和上行粗同步的参数进行上行同步。
在本公开的一种可选实施例中，下行粗同步模块具体用于：
基于采样点偏差值、以及移动卫星发送的基站空口数据帧在各预设时间单元对应的预设采样点数量，确定第一UE空口数据帧各预设时间单元对应的同步头，得到下行同步预补偿后的第一UE空口数据帧；
对每一预设时间单元按对应的同步头位置，取该预设时间单元对应的采样点进行基带处理，得到同步信号块SSB信号；
基于SSB信号中的下行同步参数进行下行粗同步。
在本公开的一种可选实施例中，下行粗同步模块进一步用于：
在UE与移动卫星距离递减的情况下，将每一预设时间单元中从同步头位置起的第一个正交频分复用OFDM符号的循环前缀CP减小采样点偏差值对应数量的采样点，并将其他OFDM符号以及CP对应的采样点数量保持不变，得到各预设时间单元对应的同步头；和/或
在UE与移动卫星距离递增的情况下，将每一预设时间单元中从同步头位置起最后一个OFDM符号增加采样点偏差值对应数量的采样点，并将其他OFDM符号以及CP对应的采样点数量保持不变，得到各预设时间单元对应的同步头。
在本公开的一种可选实施例中，下行同步参数包括同步帧头位置的本地帧号、本地时隙号、下行空口帧号、下行空口时隙号、以及下行空口时隙对应的采样点索引值；
下行粗同步模块进一步用于：
将下行空口帧号作为本地帧号，将下行空口时隙号作为本地时隙号，并基于下行空口时隙对应采样点索引值进行下一次时隙同步。
在本公开的一种可选实施例中，在本公开的一种可选实施例中，上行同步模块具体用于：
基于移动卫星与UE的实时距离，获取距离对应的第一时延，并基于下行粗同步参数获取下行粗同步对应的第二时延和第三时延；
基于第一时延、第二时延以及第三时延，获取在同步帧头位置对应的上行空口帧号、上行空口时隙帧号以及上行空口时隙对应的采样点索引值；
将上行空口帧号作为同步帧头位置的本地帧号，将上行空口时隙号作为同步帧头位置的本地时隙号，并基于上行空口时隙对应的采样点索引值进行下一次时隙同步。
在本公开的一种可选实施例中，在本公开的一种可选实施例中，上行同步模块具体用于：
基于采样点偏差值、以及移动卫星接收到的基站空口数据帧在各预设时间单元对应的预设采样点数量，确定第二UE空口数据帧的各预设时间单元对应的同步头，得到上行同步预补偿后的第二UE空口数据帧；
基于上行粗同步的参数的上行帧号、上行时隙号以及各预设时间单元对应的同步头，向移动卫星发送上行同步信号，并接收移动卫星反馈的上行残留定时偏差控制字，并基于上行残留定时偏差控制字完成上行同步。
在本公开的一种可选实施例中，在本公开的一种可选实施例中，上行同步模块进一步用于：
在UE与移动卫星距离递减的情况下，将每一预设时间单元中从同步头位置起的最后一个OFDM符号增加采样点偏差值对应数量的采样点，并将增加的采样点置零，并将其他OFDM符号以及CP对应的采样点数量 保持不变，得到各预设时间单元对应的同步头；和/或
在UE与移动卫星距离递增的情况下，将每一预设时间单元中从同步头位置起最后一个OFDM符号减少采样点偏差值对应数量的采样点，并将其他OFDM符号以及CP对应的采样点数量保持不变，得到各预设时间单元对应的同步头。
在本公开的一种可选实施例中，该装置还包括相位补偿模块，用于：
对下行同步预补偿后的第一UE空口数据帧的各预设时间单元中的各OFDM符号进行相位补偿；和/或
对上行同步预补偿后的第二UE空口数据帧的各预设时间单元中的各OFDM符号进行相位补偿。
在本公开的一种可选实施例中，相位补偿模块具体用：
基于各预设时间单元内进行上行同步预补偿的值或下行同步预补偿的值，获取各预设时间单元内每一OFDM符号对应的平均时延值；
基于平均时延值，获取每一OFDM符号在频域的每一子载波所需补偿的相位值，并基于相位值对该OFDM符号在频域进行相位补偿。
在本公开的一种可选实施例中，该装置还包括多普勒预补偿模块，用于：
对下行同步预补偿后的第一UE空口数据帧的各预设时间单元进行多普勒预补偿；和/或
对上行同步预补偿后的第二UE空口数据帧的各预设时间单元进行多普勒预补偿。
本公开实施例提供的移动卫星通信系统上下行同步装置能够实现前述结合图1至图12描述的方法实施例中实现的各个过程，为避免重复，这里不再赘述。
本公开提供的方案，分别根据预设时间单元对应的采样点偏差值进行下行同步预补偿和上行同步预补偿，使得卫星终端在本地基带采样率不变的情况下，基带处理少有累计的定时偏差，减少出现帧号和时隙号的错误，减少无线链路失败的次数，同时使得移动卫星基站上行接收多用户的物理帧时长几乎固定不变，减少上行接收多用户间的干扰，该方案能够很好适 用于移动卫星通信系统的上下行同步。
本公开实施例的移动卫星通信系统上下行同步装置可执行本公开实施例所提供的移动卫星通信系统上下行同步方法，其实现原理相类似，本公开各实施例中的移动卫星通信系统上下行同步装置中的各模块、单元所执行的动作是与本公开各实施例中的移动卫星通信系统上下行同步方法中的步骤相对应的，对于移动卫星通信系统上下行同步装置的各模块的详细功能描述具体可以参见前文中所示的对应的移动卫星通信系统上下行同步方法中的描述，此处不再赘述。
基于与本公开的实施例中所示的方法相同的原理，本公开实施例还提供了一种电子设备，该电子设备可以包括但不限于：处理器和存储器；存储器，用于存储计算机程序；处理器，用于通过调用计算机程序执行本公开的任一可选实施例所示的移动卫星通信系统上下行同步方法。与现有技术相比，本公开提供的移动卫星通信系统上下行同步方法，分别根据预设时间单元对应的采样点偏差值进行下行同步预补偿和上行同步预补偿，使得卫星终端在本地基带采样率不变的情况下，基带处理少有累计的定时偏差，减少出现帧号和时隙号的错误，减少无线链路失败的次数，同时使得移动卫星基站上行接收多用户的物理帧时长几乎固定不变，减少上行接收多用户间的干扰，该方案能够很好适用于移动卫星通信系统的上下行同步。
在一个可选实施例中，还提供了一种电子设备，如图14所示，图14所示的电子设备1400可以为服务器，包括：处理器1401和存储器1403。其中，处理器1401和存储器1403相连，如通过总线1402相连。可选地，电子设备1400还可以包括收发器1404。需要说明的是，实际应用中收发器1404不限于一个，该电子设备1400的结构并不构成对本公开实施例的限定。
处理器1401可以是CPU(Central Processing Unit，中央处理器)，通用处理器，DSP(Digital Signal Processor，数据信号处理器)，ASIC(Application Specific Integrated Circuit，专用集成电路)，FPGA(Field Programmable Gate Array，现场可编程门阵列)或者其他可编程逻辑器件、 晶体管逻辑器件、硬件部件或者其任意组合。其可以实现或执行结合本公开公开内容所描述的各种示例性的逻辑方框，模块和电路。处理器1401也可以是实现计算功能的组合，例如包含一个或多个微处理器组合，DSP和微处理器的组合等。
总线1402可包括一通路，在上述组件之间传送信息。总线1402可以是PCI(Peripheral Component Interconnect，外设部件互连标准)总线或EISA(Extended Industry Standard Architecture，扩展工业标准结构)总线等。总线1402可以分为地址总线、数据总线、控制总线等。为便于表示，图14中仅用一条粗线表示，但并不表示仅有一根总线或一种类型的总线。
存储器1403可以是ROM(Read Only Memory，只读存储器)或可存储静态信息和指令的其他类型的静态存储设备，RAM(Random Access Memory，随机存取存储器)或者可存储信息和指令的其他类型的动态存储设备，也可以是EEPROM(Electrically Erasable Programmable Read Only Memory，电可擦可编程只读存储器)、CD-ROM(Compact Disc Read Only Memory，只读光盘)或其他光盘存储、光碟存储(包括压缩光碟、激光碟、光碟、数字通用光碟、蓝光光碟等)、磁盘存储介质或者其他磁存储设备、或者能够用于携带或存储具有指令或数据结构形式的期望的程序代码并能够由计算机存取的任何其他介质，但不限于此。
存储器1403用于存储执行本公开方案的应用程序代码，并由处理器1401来控制执行。处理器1401用于执行存储器1403中存储的应用程序代码，以实现前述方法实施例所示的内容。
其中，电子设备包括但不限于：移动电话、笔记本电脑、数字广播接收器、PDA(个人数字助理)、PAD(平板电脑)、PMP(便携式多媒体播放器)、车载终端(例如车载导航终端)等等的移动终端以及诸如数字TV、台式计算机等等的固定终端。图14示出的电子设备仅仅是一个示例，不应对本公开实施例的功能和使用范围带来任何限制。
本公开提供的服务器可以是独立的物理服务器，也可以是多个物理服务器构成的服务器集群或者分布式系统，还可以是提供云服务、云移动通信、云计算、云函数、云存储、网络服务、云通信、中间件服务、域名服 务、安全服务、CDN、以及大数据和人工智能平台等基础云计算服务的云服务器。终端可以是智能手机、平板电脑、笔记本电脑、台式计算机、智能音箱、智能手表等，但并不局限于此。终端以及服务器可以通过有线或无线通信方式进行直接或间接地连接，本公开在此不做限制。
本公开实施例提供了一种计算机可读存储介质，该计算机可读存储介质上存储有计算机程序，当其在计算机上运行时，使得计算机可以执行前述方法实施例中相应内容。在一些实施例中，该计算机可读存储介质为非临时性计算机可读存储介质。
应该理解的是，虽然附图的流程图中的各个步骤按照箭头的指示依次显示，但是这些步骤并不是必然按照箭头指示的顺序依次执行。除非本文中有明确的说明，这些步骤的执行并没有严格的顺序限制，其可以以其他的顺序执行。而且，附图的流程图中的至少一部分步骤可以包括多个子步骤或者多个阶段，这些子步骤或者阶段并不必然是在同一时刻执行完成，而是可以在不同的时刻执行，其执行顺序也不必然是依次进行，而是可以与其他步骤或者其他步骤的子步骤或者阶段的至少一部分轮流或者交替地执行。
需要说明的是，本公开上述的计算机可读介质可以是计算机可读信号介质或者计算机可读存储介质或者是上述两者的任意组合。计算机可读存储介质例如可以是——但不限于——电、磁、光、电磁、红外线、或半导体的系统、装置或器件，或者任意以上的组合。计算机可读存储介质的更具体的例子可以包括但不限于：具有一个或多个导线的电连接、便携式计算机磁盘、硬盘、随机访问存储器(RAM)、只读存储器(ROM)、可擦式可编程只读存储器(EPROM或闪存)、光纤、便携式紧凑磁盘只读存储器(CD-ROM)、光存储器件、磁存储器件、或者上述的任意合适的组合。在本公开中，计算机可读存储介质可以是任何包含或存储程序的有形介质，该程序可以被指令执行系统、装置或者器件使用或者与其结合使用。而在本公开中，计算机可读信号介质可以包括在基带中或者作为载波一部分传播的数据信号，其中承载了计算机可读的程序代码。这种传播的数据信号可以采用多种形式，包括但不限于电磁信号、光信号或上述的任 意合适的组合。计算机可读信号介质还可以是计算机可读存储介质以外的任何计算机可读介质，该计算机可读信号介质可以发送、传播或者传输用于由指令执行系统、装置或者器件使用或者与其结合使用的程序。计算机可读介质上包含的程序代码可以用任何适当的介质传输，包括但不限于：电线、光缆、RF(射频)等等，或者上述的任意合适的组合。
上述计算机可读介质可以是上述电子设备中所包含的；也可以是单独存在，而未装配入该电子设备中。
上述计算机可读介质承载有一个或者多个程序，当上述一个或者多个程序被该电子设备执行时，使得该电子设备执行上述实施例所示的方法。
根据本公开的一个方面，提供了一种计算机程序产品或计算机程序，该计算机程序产品或计算机程序包括计算机指令，该计算机指令存储在计算机可读存储介质中。计算机设备的处理器从计算机可读存储介质读取该计算机指令，处理器执行该计算机指令，使得该计算机设备执行上述各种可选实现方式中提供的移动卫星通信系统上下行同步方法。
可以以一种或多种程序设计语言或其组合来编写用于执行本公开的操作的计算机程序代码，上述程序设计语言包括面向对象的程序设计语言—诸如Java、Smalltalk、C++，还包括常规的过程式程序设计语言—诸如“C”语言或类似的程序设计语言。程序代码可以完全地在用户计算机上执行、部分地在用户计算机上执行、作为一个独立的软件包执行、部分在用户计算机上部分在远程计算机上执行、或者完全在远程计算机或服务器上执行。在涉及远程计算机的情形中，远程计算机可以通过任意种类的网络——包括局域网(LAN)或广域网(WAN)—连接到用户计算机，或者，可以连接到外部计算机(例如利用因特网服务提供商来通过因特网连接)。
附图中的流程图和框图，图示了按照本公开各种实施例的系统、方法和计算机程序产品的可能实现的体系架构、功能和操作。在这点上，流程图或框图中的每个方框可以代表一个模块、程序段、或代码的一部分，该模块、程序段、或代码的一部分包含一个或多个用于实现规定的逻辑功能的可执行指令。也应当注意，在有些作为替换的实现中，方框中所标注的功能也可以以不同于附图中所标注的顺序发生。例如，两个接连地表示的 方框实际上可以基本并行地执行，它们有时也可以按相反的顺序执行，这依所涉及的功能而定。也要注意的是，框图和/或流程图中的每个方框、以及框图和/或流程图中的方框的组合，可以用执行规定的功能或操作的专用的基于硬件的系统来实现，或者可以用专用硬件与计算机指令的组合来实现。
描述于本公开实施例中所涉及到的模块可以通过软件的方式实现，也可以通过硬件的方式来实现。其中，模块的名称在某种情况下并不构成对该模块本身的限定，例如，采样点偏差值获取模块还可以被描述为“获取采样点偏差值的模块”。
以上描述仅为本公开的较佳实施例以及对所运用技术原理的说明。本领域技术人员应当理解，本公开中所涉及的公开范围，并不限于上述技术特征的特定组合而成的技术方案，同时也应涵盖在不脱离上述公开构思的情况下，由上述技术特征或其等同特征进行任意组合而形成的其它技术方案。例如上述特征与本公开中公开的(但不限于)具有类似功能的技术特征进行互相替换而形成的技术方案。

Claims (15)

  1. 一种移动卫星通信系统上下行同步方法，包括：
    基于移动卫星的星历参数和用户设备UE的坐标，获取所述UE与所述移动卫星在预设时间单元内的采样点偏差值；
    基于所述采样点偏差值对接收到的第一UE空口数据帧在对应的各预设时间单元进行下行同步预补偿，并基于下行同步预补偿后的第一UE空口数据帧进行下行粗同步；以及
    基于下行粗同步参数以及所述UE与所述移动卫星的实时距离获取上行粗同步的参数，基于所述采样点偏差值对待发射的第二UE空口数据帧在对应的各预设时间单元进行上行同步预补偿，并基于上行同步预补偿后的第二UE空口数据帧和上行粗同步的参数进行上行同步。
  2. 根据权利要求1所述的方法，其中，所述基于所述采样点偏差值对接收到的第一空口数据帧在对应的各预设时间单元进行下行同步预补偿，并基于下行同步预补偿后的第一UE空口数据帧进行下行粗同步，包括：
    基于所述采样点偏差值以及所述移动卫星发送的基站空口数据帧在各预设时间单元对应的预设采样点数量，确定所述第一UE空口数据帧各预设时间单元对应的同步头，得到所述下行同步预补偿后的第一UE空口数据帧；
    对每一预设时间单元按对应的同步头位置，取该预设时间单元对应的采样点进行基带处理，得到同步信号块SSB信号；以及
    基于所述SSB信号中的下行同步参数进行下行粗同步。
  3. 根据权利要求2所述的方法，其中，所述基于所述采样点偏差值以及所述移动卫星发送的基站空口数据帧在各预设时间单元对应的预设采样点数量，确定所述第一UE空口数据帧在各预设时间单元对应的同步头，包括：
    在所述UE与所述移动卫星距离递减的情况下，将每一预设时间单元中从所述同步头位置起的第一个正交频分复用OFDM符号的循环前缀CP 减小所述采样点偏差值对应数量的采样点，并将其他OFDM符号以及CP对应的采样点数量保持不变，得到各预设时间单元对应的同步头；和/或
    在于所述UE与所述移动卫星距离递增的情况下，将每一预设时间单元中从所述同步头位置起的最后一个OFDM符号增加所述采样点偏差值对应数量的采样点，并将其他OFDM符号以及CP对应的采样点数量保持不变，得到各预设时间单元对应的同步头。
  4. 根据权利要求2所述的方法，其中，所述下行同步参数包括同步帧头位置的本地帧号、本地时隙号、下行空口帧号、下行空口时隙号、以及所述下行空口时隙对应的采样点索引值；
    所述基于所述SSB信号中的下行同步参数进行下行粗同步，包括：
    将所述下行空口帧号作为所述本地帧号，将所述下行空口时隙号作为所述本地时隙号，并基于所述下行空口时隙对应采样点索引值进行下一次时隙同步。
  5. 根据权利要求1所述的方法，其中，基于下行粗同步参数以及UE与移动卫星的实时距离获取上行粗同步的参数，包括：
    基于所述移动卫星与所述UE的实时距离，获取所述距离对应的第一时延，并基于所述下行粗同步参数获取下行粗同步对应的第二时延和第三时延；
    基于所述第一时延、所述第二时延以及所述第三时延，获取在同步帧头位置对应的上行空口帧号、上行空口时隙帧号以及所述上行空口时隙对应的采样点索引值；
    将所述上行空口帧号作为所述同步帧头位置的本地帧号，将所述上行空口时隙号作为所述同步帧头位置的本地时隙号，并基于所述上行空口时隙对应的采样点索引值进行下一次时隙同步。
  6. 根据权利要求1所述的方法，其中，所述基于所述采样点偏差值对待发射的第二UE空口数据帧在对应的各预设时间单元进行上行同步预补偿，并基于上行同步预补偿后的第二UE空口数据帧和上行粗同步的参数进行上行同步，包括：
    基于所述采样点偏差值以及所述移动卫星接收到的基站空口数据帧 在各预设时间单元对应的预设采样点数量，确定所述第二UE空口数据帧的各预设时间单元对应的同步头，得到所述上行同步预补偿后的第二UE空口数据帧；以及
    基于上行粗同步的参数的上行帧号、上行时隙号以及各预设时间单元对应的同步头，向所述移动卫星发送上行同步信号，并接收所述移动卫星反馈的上行残留定时偏差控制字，并基于所述上行残留定时偏差控制字完成上行同步。
  7. 根据权利要求6所述的方法，其中，所述基于所述采样点偏差值以及所述移动卫星接收到的基站空口数据帧在各预设时间单元对应的预设采样点数量，确定所述第二UE空口数据帧的各预设时间单元对应的同步头，包括：
    在所述UE与所述移动卫星距离递减的情况下，将每一预设时间单元中从所述同步头位置起的最后一个OFDM符号增加所述采样点偏差值对应数量的采样点，并将增加的采样点置零，并将其他OFDM符号以及CP对应的采样点数量保持不变，得到各预设时间单元对应的同步头；和/或
    在所述UE与所述移动卫星距离递增的情况下，将每一预设时间单元中从所述同步头位置起最后一个OFDM符号减少所述采样点偏差值对应数量的采样点，并将其他OFDM符号以及CP对应的采样点数量保持不变，得到各预设时间单元对应的同步头。
  8. 根据权利要求1所述的方法，其中，所述方法还包括：
    对所述下行同步预补偿后的第一UE空口数据帧的各预设时间单元中的各OFDM符号进行相位补偿；和/或
    对所述上行同步预补偿后的第二UE空口数据帧的各预设时间单元中的各OFDM符号进行相位补偿。
  9. 根据权利要求8所述的方法，其中，所述对各预设时间单元中的各OFDM符号进行相位补偿，包括：
    基于各预设时间单元内进行上行同步预补偿的值或下行同步预补偿的值，获取各预设时间单元内每一OFDM符号对应的平均时延值；以及
    基于所述平均时延值，获取每一OFDM符号在频域的每一子载波所 需补偿的相位值，并基于所述相位值对该OFDM符号在频域进行相位补偿。
  10. 根据权利要求1-9中任一项所述的方法，其中，所述方法还包括：
    对所述下行同步预补偿后的第一UE空口数据帧的各预设时间单元进行多普勒预补偿；和/或
    对所述上行同步预补偿后的第二UE空口数据帧的各预设时间单元进行多普勒预补偿。
  11. 一种移动卫星通信系统上下行同步装置，包括：
    采样点偏差值获取模块，用于基于移动卫星的星历参数和用户设备UE的坐标，获取所述UE与所述移动卫星在预设时间单元内的采样点偏差值；
    下行粗同步模块，用于基于所述采样点偏差值对接收到的第一UE空口数据帧在对应的各预设时间单元进行下行同步预补偿，并基于下行同步预补偿后的第一UE空口数据帧进行下行同步；
    上行同步模块，用于基于下行粗同步参数以及UE与移动卫星的实时距离获取上行粗同步的参数，基于所述采样点偏差值对待发射的第二UE空口数据帧在对应的各预设时间单元进行上行同步预补偿，并基于上行同步预补偿后的第二UE空口数据帧和上行粗同步的参数进行上行同步。
  12. 根据权利要求11所述的装置，其中，下行粗同步模块具体用于：
    基于所述采样点偏差值以及所述移动卫星发送的基站空口数据帧在各预设时间单元对应的预设采样点数量，确定所述第一UE空口数据帧各预设时间单元对应的同步头，得到所述下行同步预补偿后的第一UE空口数据帧；
    对每一预设时间单元按对应的同步头位置，取该预设时间单元对应的采样点进行基带处理，得到同步信号块SSB信号；以及
    基于所述SSB信号中的下行同步参数进行下行粗同步。
  13. 根据权利要求11所述的装置，其中，上行同步模块具体用于：
    基于所述采样点偏差值以及所述移动卫星接收到的基站空口数据帧在各预设时间单元对应的预设采样点数量，确定所述第二UE空口数据帧 的各预设时间单元对应的同步头，得到所述上行同步预补偿后的第二UE空口数据帧；以及
    基于上行粗同步的参数的上行帧号、上行时隙号以及各预设时间单元对应的同步头，向所述移动卫星发送上行同步信号，并接收所述移动卫星反馈的上行残留定时偏差控制字，并基于所述上行残留定时偏差控制字进行上行同步。
  14. 一种电子设备，包括存储器、处理器及存储在存储器上并可在处理器上运行的计算机程序，处理器执行计算机程序时实现权利要求1至10中任一项的方法。
  15. 一种计算机可读存储介质，计算机可读存储介质上存储有计算机程序，计算机程序被处理器执行时实现权利要求1至10中任一项的方法。
PCT/CN2023/097855 2022-06-01 2023-06-01 移动卫星通信系统上下行同步方法及装置 WO2023232116A1 (zh)

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