WO2022021439A1 - 直通链路同步信号的发送方法和装置 - Google Patents

直通链路同步信号的发送方法和装置 Download PDF

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Publication number
WO2022021439A1
WO2022021439A1 PCT/CN2020/106444 CN2020106444W WO2022021439A1 WO 2022021439 A1 WO2022021439 A1 WO 2022021439A1 CN 2020106444 W CN2020106444 W CN 2020106444W WO 2022021439 A1 WO2022021439 A1 WO 2022021439A1
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subframe
dfn
radio frame
frame period
subframes
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PCT/CN2020/106444
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English (en)
French (fr)
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邓猛
孙学全
张东风
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华为技术有限公司
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Priority to PCT/CN2020/106444 priority Critical patent/WO2022021439A1/zh
Priority to CN202310296000.XA priority patent/CN116347587A/zh
Priority to CN202080014937.8A priority patent/CN114270939B/zh
Publication of WO2022021439A1 publication Critical patent/WO2022021439A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W56/00—Synchronisation arrangements
    • H04W56/001—Synchronization between nodes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/06—Reselecting a communication resource in the serving access point
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W76/00—Connection management
    • H04W76/10—Connection setup
    • H04W76/14—Direct-mode setup
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/30—Services specially adapted for particular environments, situations or purposes
    • H04W4/40—Services specially adapted for particular environments, situations or purposes for vehicles, e.g. vehicle-to-pedestrians [V2P]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/30—Services specially adapted for particular environments, situations or purposes
    • H04W4/40—Services specially adapted for particular environments, situations or purposes for vehicles, e.g. vehicle-to-pedestrians [V2P]
    • H04W4/46—Services specially adapted for particular environments, situations or purposes for vehicles, e.g. vehicle-to-pedestrians [V2P] for vehicle-to-vehicle communication [V2V]

Definitions

  • the present application relates to the field of communication technologies, and in particular, to a method and apparatus for sending a direct link synchronization signal.
  • the 3rd generation partnership project (3GPP) formulated the long term evolution (LTE)-based vehicle to everything (V2X) technology.
  • LTE long term evolution
  • V2X vehicle to everything
  • the process of sending and receiving a sidelink synchronization signal, wherein the subframe position of the subframe used to send the sidelink synchronization signal is defined is indicated by three preconfigured parameters syncOffsetIndicator1, syncOffsetIndicator2, and syncOffsetIndicator3.
  • syncOffsetIndicator1 the process of sending and receiving the cut-through link synchronization signal defined in 3GPP is deleted, and the pre-configured parameter syncOffsetIndicator1 is also deleted.
  • V2X terminal devices cannot send through-link synchronization signals through the PC5 interface to achieve synchronization between V2X terminal devices.
  • the embodiments of the present application provide a method and apparatus for sending a direct link synchronization signal, which can solve the Chinese industry standard based on LTE-V2X, and a terminal device cannot send a direct link synchronization signal through a PC5 interface to establish communication with other terminal devices. Synchronization problem.
  • an embodiment of the present application provides a method for sending a direct link synchronization signal.
  • the method includes: a terminal device determines a target subframe from reserved subframes or preconfigured subframes included in a radio frame period, and sends a direct link synchronization signal in the target subframe.
  • the radio frame period includes 10240 subframes, the 10240 subframes include 40 reserved subframes, and the preconfigured subframe is the subframe indicated by a bit in the subframe configuration bitmap with a bit value of 0 in the radio frame period .
  • the through link synchronization signal includes the through link primary synchronization signal PSSS, the through link secondary synchronization signal SSSS, the physical through link broadcast channel PSBCH and the demodulation reference signal DMRS.
  • the direct link synchronization signal in the embodiment of the present application conforms to the Internet of Vehicles standard formulated by 3GPP, and specifically includes four parts, namely PSSS, SSSS, PSBCH, and DMRS, and the format and content of each part can be found in 3GPP. Definition.
  • the terminal device by determining the target subframe from the reserved subframes or preconfigured subframes included in the radio frame period, and sending the direct link synchronization signal in the target subframe, the LTE-V2X-based According to Chinese industry standards, the terminal device cannot send a straight-through link synchronization signal through the PC5 interface to establish synchronization with other terminal devices.
  • the direct frame numbers DFN f and DFN subframe numbers s of the reserved subframes in the radio frame period satisfy:
  • n is an integer and 0 ⁇ m ⁇ 39.
  • each consecutive 100 subframes in the 10200 subframes except the 40 reserved subframes in the radio frame period is indicated by a subframe configuration bitmap, and the subframe configuration
  • the bitmap includes 100 bits, and one bit indicates one subframe, wherein each consecutive 100 subframes includes one preconfigured subframe indicated by one bit whose bit value is 0 in the subframe configuration bitmap.
  • the target subframe is a preconfigured subframe included in the radio frame period, and the DFN f of the target subframe and DFN subframe number s satisfies:
  • s if ⁇ 10, n is an odd number less than 102;
  • k is a bit sequence number corresponding to a bit whose bit value is 0 in the subframe configuration bitmap. It should be understood that when the terminal device cannot obtain the GNSS signal, it can be understood that the terminal device has no reference synchronization source, that is, the reference synchronization source of the terminal device is empty, so the terminal device enters the self-synchronization state. Specifically, there are two situations in which the terminal device cannot obtain the GNSS signal. One situation is that the terminal device does not receive the GNSS signal, and the other situation is that the terminal device can receive the GNSS signal, but the received GNSS signal does not conform to the signal. Quality requirements.
  • the terminal device when the terminal device cannot obtain the GNSS signal, by determining the preconfigured subframe as the target subframe, and sending the direct link synchronization signal on the target subframe, it is possible to solve the problem of China's LTE-V2X-based Industry standard, when the terminal equipment cannot receive the GNSS signal that meets the signal quality requirements, the synchronization between the terminal equipment cannot be established.
  • the target subframe is a preconfigured subframe included in the radio frame period, and the DFN f and DFN subframe number of the target subframe are s satisfy:
  • s if ⁇ 10, n is an even number less than 102;
  • k is a bit sequence number corresponding to a bit whose bit value is 0 in the subframe configuration bitmap.
  • the terminal device when the terminal device cannot obtain the GNSS signal, by determining the preconfigured subframe as the target subframe, and sending the direct link synchronization signal on the target subframe, it is possible to solve the problem of China's LTE-V2X-based Industry standard, when the terminal equipment cannot receive the GNSS signal that meets the signal quality requirements, the synchronization between the terminal equipment cannot be established.
  • the target subframe is the reserved subframe included in the radio frame period. It should be understood that when the terminal device acquires the GNSS signal, it can be understood that the reference synchronization source of the terminal device is GNSS.
  • the terminal device when the terminal device acquires the GNSS signal, by determining the reserved subframe included in the radio frame period as the target subframe, and sending the direct link synchronization signal in the target subframe, it is possible to solve the problem based on the According to the Chinese industry standard of LTE-V2X, the terminal device can only receive GNSS signals, but cannot send the direct link synchronization signal.
  • the terminal device when the terminal device determines that the target subframe is a preconfigured subframe, before the terminal device sends the direct link synchronization signal in the target subframe, the terminal device can also obtain the signal to send control parameter. Wherein, if the signal transmission control parameter indicates that the preconfigured subframe included in the radio frame period is used for transmitting the direct link synchronization signal, the terminal device may perform the step of sending the direct link synchronization signal in the target subframe.
  • the controllability of the terminal device when transmitting the direct link synchronization signal can be improved.
  • the terminal device when the terminal device determines that the target subframe is a reserved subframe, before the terminal device sends the direct link synchronization signal in the target subframe, the terminal device can also obtain the signal to send. control parameter. If the signal transmission control parameter indicates that the reserved subframe included in the radio frame period is used for transmitting the direct link synchronization signal, the step of transmitting the direct link synchronization signal in the target subframe is performed.
  • the terminal device when the terminal device determines that the target subframe is a reserved subframe, if the acquired signal transmission control parameter indicates that the reserved subframe in the radio frame period is not used for sending direct transmission
  • the terminal device may further determine the target subframe from the preconfigured subframes included in the radio frame period, and send the through link synchronization signal on the redetermined target subframe.
  • the DFN f and the DFN subframe number s of the re-determined target subframe satisfy:
  • s if ⁇ 10, n is an odd number less than 102;
  • k is a bit sequence number corresponding to a bit whose bit value is 0 in the subframe configuration bitmap.
  • the terminal device when the signal transmission control parameter indicates that the reserved subframes in the radio frame period are not used for transmitting the direct link synchronization signal, the terminal device re-determines the target subframe from the preconfigured subframes included in the radio frame period, And the direct link synchronization signal is sent on the re-determined target subframe, which can improve the transmission success rate of the direct link synchronization signal.
  • the terminal device when the terminal device determines that the target subframe is a reserved subframe, if the acquired signal transmission control parameter indicates that the reserved subframe in the radio frame period is not used for sending direct transmission
  • the terminal device may re-determine the target subframe from the preconfigured subframes included in the radio frame period, and send the through link synchronization signal on the re-determined target subframe.
  • the DFN f and the DFN subframe number s of the re-determined target subframe satisfy:
  • s if ⁇ 10, n is an even number less than 102;
  • k is a bit sequence number corresponding to a bit whose bit value is 0 in the subframe configuration bitmap.
  • the terminal device when the signal transmission control parameter indicates that the reserved subframes in the radio frame period are not used for transmitting the direct link synchronization signal, the terminal device re-determines the target subframe from the preconfigured subframes included in the radio frame period, And the direct link synchronization signal is sent on the re-determined target subframe, which can improve the transmission success rate of the direct link synchronization signal.
  • an embodiment of the present application provides a method for sending a direct link synchronization signal.
  • the method includes: a first terminal device receiving a first through link synchronization signal from a second terminal device.
  • the first through link synchronization signal carries the first DFN and the first DFN subframe number, and the first DFN and the first DFN subframe number are used to indicate the first subframe.
  • the first terminal device determines a target subframe from preconfigured subframes included in the radio frame period based on the first subframe, and sends a second through link synchronization signal in the target subframe.
  • the radio frame period includes 10240 subframes, the 10240 subframes include 40 reserved subframes, and the preconfigured subframe is the subframe indicated by a bit in the subframe configuration bitmap with a bit value of 0 in the radio frame period .
  • the through-link synchronization signal (the first through-link synchronization signal and the second through-link synchronization signal) involved in the embodiments of the present application all conform to the Internet of Vehicles standard formulated by 3GPP, and specifically includes four parts, respectively: PSSS, SSSS, PSBCH and DMRS, the format and content of each part can refer to the definition in 3GPP.
  • the first DFN and the first DFN subframe number carried in the first through-link synchronization signal are obtained from the pre-configured subframe.
  • the target subframe is determined in the target subframe to send the second cut-through link synchronization signal in the target subframe, which solves the Chinese industry standard based on LTE-V2X, how to send the cut-through link when the terminal device uses another terminal device as the reference synchronization source.
  • the first terminal device may monitor the through-link synchronization signal in the time domain for a signal monitoring period of 256 ms to receive the through-link synchronization signal.
  • the DFN f and the DFN subframe number s of the reserved subframes in the radio frame period satisfy:
  • n is an integer and 0 ⁇ m ⁇ 39.
  • each consecutive 100 subframes in the 10200 subframes except the 40 reserved subframes in the radio frame period is indicated by a subframe configuration bitmap, and the subframe configuration
  • the bitmap includes 100 bits, and one bit indicates one subframe, wherein each consecutive 100 subframes includes one preconfigured subframe indicated by one bit whose bit value is 0 in the subframe configuration bitmap.
  • the preconfigured subframes included in the radio frame period include the first type of preconfigured subframes and the second type of preconfigured subframes.
  • the DFN f and DFN subframe number s of the first type of preconfigured subframe satisfy:
  • s if ⁇ 10, n is odd and 0 ⁇ n ⁇ 101;
  • the DFN f and DFN subframe number s of the second type of preconfigured subframe satisfy:
  • s if ⁇ 10, n is an even number and 0 ⁇ n ⁇ 101;
  • k is a bit sequence number corresponding to a bit whose bit value is 0 in the subframe configuration bitmap.
  • the target subframe is the second type of preconfigured subframe included in the radio frame period.
  • the target subframe is the first type of preconfigured subframe included in the radio frame period.
  • the target subframe is the first type of preconfigured subframe in the radio frame period.
  • the target subframe is the second type of preconfigured subframe in the radio frame period.
  • the first terminal device may also obtain the signal transmission control parameter, if the signal transmission control parameter indicates that the preconfigured subframe included in the radio frame period is used for transmitting the direct link synchronization signal , the step of sending the second direct link synchronization signal in the target subframe is performed.
  • an embodiment of the present application provides an apparatus for sending a direct link synchronization signal.
  • the sending device may be the terminal device itself, or may be an element or module inside the terminal device such as a chip or the like.
  • the communication device includes a unit for executing the method for sending a direct link synchronization signal provided by any possible implementation manner of the first aspect and/or the second aspect, and therefore can also implement the first aspect and/or The beneficial effects (or advantages) of the method for sending a direct link synchronization signal provided by the second aspect.
  • an embodiment of the present application provides an apparatus for sending a direct link synchronization signal
  • the sending apparatus may be a terminal device.
  • the communication device includes at least one memory, a transceiver, and a processor.
  • the processor and the transceiver are configured to invoke the code stored in the memory to execute the method for sending a cut-through link synchronization signal provided by any feasible implementation manner of the first aspect and/or the second aspect.
  • an embodiment of the present application provides an apparatus for sending a direct link synchronization signal
  • the communication apparatus may be a terminal device.
  • the communication device includes: at least one processor and an interface circuit.
  • the interface circuit is used to receive code instructions and transmit them to the processor.
  • the processor is configured to run the above code instructions to implement the method for sending a direct link synchronization signal provided by any feasible implementation manner of the above first aspect and/or the second aspect, and can also implement the above first aspect and/or The beneficial effects (or advantages) of the method for sending a direct link synchronization signal provided by the second aspect.
  • an embodiment of the present application provides a computer-readable storage medium, where an instruction is stored in the computer-readable storage medium, and when the instruction is executed on a computer, the above-mentioned first aspect and/or the second aspect is implemented.
  • the method for sending a direct link synchronization signal provided by any feasible implementation mode can also realize the beneficial effects (or advantages) possessed by the method for sending a direct link synchronization signal provided by the first aspect and/or the second aspect. ).
  • an embodiment of the present application provides a computer program product including instructions, which, when the computer program product is run on a computer, causes the computer to execute the cut-through link synchronization signal provided in the first aspect and/or the second aspect.
  • the sending method can also achieve the beneficial effects of the direct link synchronization signal sending method provided by the first aspect and/or the second aspect.
  • the method provided by the embodiments of the present application can solve the problem that a terminal device cannot send a direct link synchronization signal through the PC5 interface based on the Chinese industry standard of LTE-V2X to establish synchronization with other terminal devices.
  • FIG. 1 is a schematic diagram of a system architecture of a V2X communication system provided by an embodiment of the present application
  • FIG. 2 is a schematic structural diagram of a radio frame period provided by an embodiment of the present application.
  • FIG. 3 is a schematic flowchart of a method for sending a direct link synchronization signal provided by an embodiment of the present application
  • FIG. 4 is another schematic flowchart of a method for sending a direct link synchronization signal provided by an embodiment of the present application
  • FIG. 5 is a schematic structural diagram of a device for sending a direct link synchronization signal according to an embodiment of the present application
  • FIG. 6 is another schematic structural diagram of an apparatus for sending a direct link synchronization signal according to an embodiment of the present application.
  • V2X communication technology is one of the important communication technologies in the field of Internet of Vehicles. communication between vehicles and personal devices (vehicle to pedestrian, V2P).
  • V2P vehicle to pedestrian
  • the communication between V2P may be the communication between the vehicle-mounted terminal and the handheld terminal of a pedestrian, driver or passenger, etc., which is not limited here.
  • V2X communication technology has been widely used.
  • FIG. 1 is a schematic diagram of a system architecture of a V2X communication system provided by an embodiment of the present application.
  • a V2X communication system may include a global navigation satellite system (GNSS), an onboard unit (OBU), a roadside unit (RSU), a mobile terminal, and the like.
  • GNSS global navigation satellite system
  • OBU onboard unit
  • RSU roadside unit
  • mobile terminal and the like.
  • various types of terminal equipment such as OBU, RSU, mobile terminal, etc.
  • terminal equipment may be a chip, or may be a user equipment including a chip.
  • the chip when the terminal device is a chip, the chip may include a processor and an interface.
  • the terminal device when the terminal device is a user equipment including a chip, the terminal device may be an OBU, an RSU, a mobile terminal, a subscriber unit, a subscriber station, a mobile station, a mobile station, a remote station (remote station), access point (AP), remote terminal (remote terminal), access terminal (access terminal), user terminal (user terminal), user agent (user agent), or user equipment (user device), etc.
  • mobile terminals may include mobile phones (or “cellular" phones), computers, tablet computers, smart phones, personal digital assistants (PDAs), mobile Internet devices (MIDs) and smart wearables type equipment, etc.
  • the mobile terminal may also be a portable, pocket-sized, hand-held, computer-built or vehicle-mounted mobile device, etc., which is not limited herein.
  • the number of terminal devices of the same type may be one or more, which is not limited here.
  • the OBU in FIG. 1 may include OBU1 and OBU2.
  • the GNSS may include the global positioning system (GPS) of the United States, the GLONASS satellite navigation system (GLONASS) of Russia, and the Galileo satellite navigation system of the European Union. (galileo satellite navigation system, GALILEO), and China's Beidou satellite navigation system (beidou navigation satellite system, BDS) and other one or more positioning systems.
  • GPS global positioning system
  • GLONASS GLONASS satellite navigation system
  • GALILEO Galileo satellite navigation system
  • Beidou satellite navigation system beidou navigation satellite system
  • BDS Beidou navigation satellite system
  • the GNSS can communicate with each terminal device, and each terminal device can also communicate with each other.
  • the GNSS can communicate with each OBU and the mobile terminal, each OBU can communicate with the RSU and the mobile terminal, and each OBU can also communicate with each other.
  • V2X communication mainly involves two communication interfaces, namely the PC5 interface and the Uu interface.
  • the V2X communication based on the PC5 interface is the direct communication or sideline communication between terminal devices. link. That is to say, V2X communication based on the PC5 interface is direct communication between terminal devices, which does not need to be forwarded through network devices.
  • the V2X communication based on the Uu interface requires the sender terminal device to send the V2X data to the network device through the Uu interface, and the network device sends the V2X data to the V2X application server for processing, and then the V2X application server sends it to the receiver terminal device.
  • the present application may be applicable to scenarios in which sideline communication is performed between various terminal devices.
  • the sideline communication involved in this application may be unicast communication between a pair of terminal devices, multicast or multicast communication between a terminal device and a group of terminal devices, or It is a broadcast communication between one terminal device and an unlimited number of terminal devices, etc., which is specifically determined according to the actual application scenario, and is not limited here.
  • the terminal device is an on-board unit (OBU1 and OBU2 in Fig. 1) installed on the vehicle, when the on-board unit moves with the vehicle at high speed, as shown in Fig. 1, when OBU1 and OBU2 move with each other , in order to ensure reliable communication between OBU1 and OBU2, OBU1 and OBU2 need to be synchronized.
  • OBU1 and OBU2 on-board unit
  • the terminal device when a terminal device uses the Internet of Vehicles standard formulated by CCSA for V2X communication, the terminal device cannot send a through-link synchronization signal through the PC5 interface to establish synchronization between terminal devices, especially when the various components in the V2X communication system
  • the terminal device cannot receive the GNSS signal that meets the signal quality requirements, the synchronization between the terminal devices will be unable to be performed, thereby causing the V2X communication system to fail to work normally.
  • the present application provides a direct link synchronization signal sending method, which can determine the target subframe used for sending the direct link synchronization signal under the LTE-V2X China industry standard formulated by the existing CCSA, and A cut-through link synchronization signal is sent in the target subframe to achieve synchronization between terminal devices.
  • FIG. 2 is a schematic structural diagram of a radio frame period provided by an embodiment of the present application.
  • one radio frame period may include 1024 radio frames.
  • a radio frame can be indicated by a direct frame number (DFN), therefore, the value of DFN in each radio frame period ranges from 0 to 1023.
  • each subframe included in each radio frame can be indicated by a DFN subframe number, so the value range of the DFN subframe number in each radio frame is 0-9. That is, each subframe included in each radio frame period may be jointly indicated by the DFN and the DFN subframe number.
  • DFN direct frame number
  • a radio frame period includes a total of 40 reserved subframes.
  • the DFN f and DFN subframe number s of the 40 reserved subframes satisfy:
  • m is an integer and 0 ⁇ m ⁇ 39. That is to say, the 0th subframe in each radio frame period (that is, the subframe with DFN 0 and DFN subframe number 0), the 256th subframe (that is, the subframe with DFN 25 and DFN subframe number 6) frame), the 512th subframe (that is, the subframe whose DFN is 51 and the DFN subframe number is 2), ..., the 9984th subframe (that is, the subframe whose DFN is 998 and the DFN subframe number is 4) are all pre- Leave subframes. Alternatively, it can also be said that the subframe types of these subframes are reserved subframes.
  • each consecutive 100 subframes in the 10200 subframes except the 40 reserved subframes in the radio frame period are indicated by a subframe configuration bitmap bitmap.
  • the subframe configuration bitmap includes 100 bits, that is, the length of the subframe configuration bitmap is 100 bits, and one bit indicates one subframe. That is to say, 10200 subframes except 40 reserved subframes in each radio frame period can be indicated by a total of 102 identical subframe configuration bitmaps.
  • the first subframe (that is, the subframe whose DFN is 0 and the DFN subframe number is 1) to the 100th subframe (that is, the subframe whose DFN is 10 and the DFN subframe number is 0) ) can be indicated by a subframe configuration bitmap, the 101st subframe (that is, the subframe whose DFN is 10 and the DFN subframe number is 1) to the 200th subframe (that is, the DFN is 20, the DFN subframe is 1) in each radio frame period
  • the subframe whose frame number is 0) can be indicated by one of the above subframe configuration bitmaps, and the 201st subframe (that is, the subframe whose DFN is 20 and the DFN subframe number is 1) to the 255th subframe in each radio frame period (that is, the subframe whose DFN is 25 and the DFN subframe number is 5), the 257th subframe (that is, the subframe whose DFN is 25 and the DFN subframe number is 7)
  • one bit in the subframe configuration bitmap corresponds to one bit sequence number. Therefore, the value range of the bit sequence number corresponding to 100 bits is 0-99. Generally speaking, each bit includes a bit value, and the value of the bit value of each bit can be 0 or 1.
  • each consecutive 100 subframes includes one preconfigured subframe indicated by a bit whose bit value is 0 in the subframe configuration bitmap. That is to say, the preconfigured subframe is a subframe corresponding to a bit whose bit value is 0 in the subframe configuration bitmap. It can be seen from this that a radio frame period includes 102 preconfigured subframes in total.
  • the subframe configuration bitmap includes 1 bit with a value of 0 and 99 bits with a value of 1, the subframe corresponding to the one bit with a value of 0 is for preconfigured subframes.
  • the subframe configuration bitmap includes 1 bit with a bit value of 0 in total, and the bit sequence number corresponding to the above 1 bit with a bit value of 0 is 0. Therefore, the subframe corresponding to the bit sequence number 0 in each radio frame period may be determined as the preconfigured subframe.
  • the subframe configuration bitmap includes n bits with a value of 0 and (100-n) bits with a value of 1, it can be randomly selected from the n bits with a value of 0.
  • a subframe corresponding to a bit with a bit value of 0 is determined as a preconfigured subframe, where n is an integer greater than 1 and less than 100.
  • the subframe corresponding to the bit with the smallest bit sequence number among the n bits with a value of 0 may be determined as a preconfigured subframe, or, among the n bits with a value of 0, the bit
  • the subframe corresponding to the bit with the largest bit sequence number is determined as the preconfigured subframe, which may be agreed in advance according to actual needs, and is not limited here.
  • the subframe configuration bitmap includes 3 bits with a bit value of 0 in total, wherein the bit numbers corresponding to the above 3 bits with a bit value of 0 are 0, 1, and 2, respectively.
  • the pre-configured subframe is pre-agreed as the subframe corresponding to the bit with the smallest bit sequence number
  • the subframe corresponding to the bit sequence number 0 in the radio frame period may be determined as the pre-configured subframe.
  • the subframe corresponding to the bit sequence number 2 in the radio frame period may be determined as the preconfigured subframe.
  • n is an integer and 0 ⁇ n ⁇ 101
  • k is a bit sequence number corresponding to a bit whose bit value is 0 in the subframe configuration bitmap.
  • the preconfigured subframes may be divided into the first type of preconfigured subframes and the second type of preconfigured subframes according to the different occurrence positions of the preconfigured subframes in the radio frame period.
  • the preconfigured subframes of the first type and the preconfigured subframes of the second type alternately appear in the radio frame period. It can be seen from this that the radio frame period includes 51 preconfigured subframes of the first type and 51 preconfigured subframes of the second type.
  • a preconfigured subframe included in the 1st subframe to the 100th subframe in the radio frame period is the first type of preconfigured subframe
  • the 101st subframe to the 200th subframe in the radio frame period A preconfigured subframe included in the subframes is the second type of preconfigured subframes
  • the 201st subframe to the 255th subframe and the 257th subframe to the 301st subframe in the radio frame period include a preconfigured subframe.
  • the configured subframe is the first type of preconfigured subframe, and so on, and one preconfigured subframe included in the 10140th subframe to the 10239th subframe in the radio frame period is the second type of preconfigured subframe.
  • a pre-configured subframe included in the 1st subframe to the 100th subframe in the radio frame period is a preconfigured subframe of the second type
  • the 101st subframe to the 101st subframe to the 100th subframe in the radio frame period One preconfigured subframe included in the 200 subframes is the first type of preconfigured subframe, then one of the 201st subframe to the 255th subframe and the 257th subframe to the 301st subframe in the radio frame period
  • the preconfigured subframe is the second type of preconfigured subframe, and so on, one preconfigured subframe included in the 10140th subframe to the 10239th subframe in the radio frame period is the first type of preconfigured subframe.
  • the preconfigured subframes included in the first subframe to the 100th subframe in the radio frame period are the second type preconfigured subframes
  • the 51 first type preconfigured subframes included in the radio frame period When DFN f and DFN subframe number s are expressed by formulas, they satisfy:
  • s if ⁇ 10, n is odd and 0 ⁇ n ⁇ 101;
  • s if ⁇ 10, n is an even number and 0 ⁇ n ⁇ 101;
  • k is a bit sequence number corresponding to a bit whose bit value is 0 in the subframe configuration bitmap.
  • the preconfigured subframes included in the first subframe to the 100th subframe in the radio frame period are the first type of preconfigured subframes
  • the 51 first type of preconfigured subframes included in the radio frame period When the DFN f and DFN subframe number s of a frame are expressed by formulas, they satisfy:
  • s if ⁇ 10, n is an even number and 0 ⁇ n ⁇ 101;
  • s if ⁇ 10, n is odd and 0 ⁇ n ⁇ 101;
  • k is a bit sequence number corresponding to a bit whose bit value is 0 in the subframe configuration bitmap.
  • FIG. 3 is a schematic flowchart of a method for sending a direct link synchronization signal provided by an embodiment of the present application.
  • a terminal device determines a target subframe from reserved subframes or preconfigured subframes included in a radio frame period.
  • the terminal device can determine the reference synchronization source by searching or detecting the synchronization signal.
  • the synchronization source that sends the synchronization signal may be determined as the reference synchronization source.
  • the terminal device is an OBU set on a vehicle
  • the terminal device moves with the vehicle or stays on an open road
  • the terminal device can determine the reference synchronization
  • the source is GNSS.
  • the signal quality may be measured based on parameters such as signal strength, signal received power, or signal-to-noise ratio, which is not limited herein.
  • the terminal device is a terminal device that supports the Internet of Vehicles standard formulated by CCSA. That is to say, the terminal device in the embodiment of the present application is a terminal device that performs V2X communication according to the Internet of Vehicles standard formulated by CCSA.
  • the terminal device when the terminal device cannot obtain the GNSS signal, it may be determined that the reference synchronization source is empty, and the terminal device enters the self-synchronization state at this time. It is not difficult to understand that there are two situations in which the terminal device cannot obtain GNSS signals. One situation is that the terminal device does not search or detect GNSS signals, and the other situation is that the terminal device can search for or detect GNSS signals, but the GNSS signals are not detected. The signal quality of the signal does not meet the signal quality requirements.
  • the terminal device when the terminal device moves from an open area with strong GNSS signals into a tunnel, a canyon, or an underground parking lot, the terminal device may search for Or the GNSS signal that meets the signal quality requirements cannot be detected. Therefore, the terminal device can enter the self-synchronization state when searching for or failing to detect GNSS signals that meet the signal quality requirements.
  • the terminal device may determine the DFN and the DFN subframe number according to the GNSS signal sent by the GNSS.
  • the GNSS signal includes timing information, and the timing information includes the current world unified time (coordinated universal time, UTC).
  • the terminal device can calculate the DFN and DFN subframe numbers respectively by the following formulas according to the timing information:
  • DFN subframe number Floor(Tcurrent-Tref-offsetDFN)mod 10
  • Tcurrent is the current UTC time included in the timing information (the value is expressed in milliseconds)
  • Tref is the UTC reference time
  • offsetDFN is the offset value, which is expressed in milliseconds and ranges from 0ms to 1ms.
  • the terminal device can determine the time domain range of the current radio frame period based on the DFN and DFN subframe numbers calculated above, and keep synchronization with the GNSS in the time domain. That is, the terminal device may use the DFN and DFN subframe numbers calculated above as the starting subframe position for cyclic counting of subsequent subframes. Further, the terminal device may determine the reserved subframe after the position of the starting subframe as the target subframe. That is, the target subframes are reserved subframes included in the current radio frame period and each radio frame period after the current radio frame period.
  • the current radio frame period includes a total of 39 target subframes, which are the 256th subframe in the current radio frame period (that is, the subframe whose DFN is 25 and the DFN subframe number is 6), and the 512th subframe (that is, the DFN subframe). is 51, the subframe whose DFN subframe number is 2), ..., the 9984th subframe (that is, the subframe whose DFN is 998 and whose DFN subframe number is 4).
  • the terminal device when the terminal device enters the self-synchronization state, if the terminal device can read the DFN and DFN subframe numbers stored in advance, the DFN and DFN subframe numbers can be used as the starting subframe for cyclic counting of subsequent subframes. frame position, and further, after the starting subframe position, a subframe belonging to the first type of preconfigured subframe or a subframe of the second type of preconfigured subframe is determined as the target subframe.
  • the above-mentioned pre-stored DFN and DFN subframe numbers may be the DFN and DFN subframe numbers determined when the terminal device uses the GNSS as a reference synchronization source most recently. Wherein, each time the terminal device performs synchronization with the reference synchronization source, the DFN and DFN subframe numbers can be updated and stored as the DFN and DFN subframe numbers determined by the current synchronization process.
  • the terminal device when the terminal device is a new device, or when the terminal device is in the initial state after being shut down and restarted, or when the terminal device has never used GNSS as the reference synchronization source since it was turned on, the The stored DFN and DNF subframe numbers are empty. At this time, the terminal device cannot read the DFN and DFN subframe numbers. Therefore, the terminal device can randomly determine a DFN and a DFN subframe number as the starting subframe position for cyclic counting of subsequent subframes, and then use the first type preconfigured subframe or the second type preconfigured subframe after the starting subframe position The subframe is determined as the target subframe.
  • the terminal device sends a cut-through link synchronization signal in the target subframe.
  • the terminal device after the terminal device determines the target subframe, it can directly send the direct link synchronization signal on the target subframe.
  • the sidelink synchronization signal includes a primary sidelink synchronization signal (PSSS), a secondary sidelink synchronization signal (SSSS), a physical sidelink broadcast channel (physical sidelink). broadcast channel, PSBCH) and demodulation reference signals (demodulation reference signals, DMRS).
  • PSSS primary sidelink synchronization signal
  • SSSS secondary sidelink synchronization signal
  • a physical sidelink broadcast channel physical sidelink broadcast channel (physical sidelink). broadcast channel, PSBCH) and demodulation reference signals (demodulation reference signals, DMRS).
  • PSSS primary sidelink synchronization signal
  • SSSS secondary sidelink synchronization signal
  • DMRS demodulation reference signals
  • Section 9.6 for the format and content of PSBCH, refer to Section 9.6 in the 3GPP 36.211 standard and 3GPP 36.331 standard.
  • Section 5.10.7.4 of DMRS please refer to Section 9.8 and Section 5.5.2.1 in the 3GPP36.211 standard for the format and content of DMRS.
  • the terminal device may also transmit control parameters by acquiring the signal, and transmit the control parameters according to the signal. It is further determined whether to send a direct link synchronization signal in the target subframe.
  • the signal transmission control parameters can be preset when the terminal equipment leaves the factory.
  • the signaling control parameters can be programmed in advance or stored in the terminal device. Therefore, when the terminal device reads the signal transmission control parameter, if the signal transmission control parameter indicates that the determined target subframe is used to transmit the direct link synchronization signal, the terminal device can send the direct link synchronization signal in the target subframe .
  • the signal transmission control parameters are obtained, if the signal If the transmission control parameter indicates that the preconfigured subframe included in the radio frame period is used for transmitting the direct link synchronization signal, the direct link synchronization signal is transmitted in the target subframe.
  • the signal transmission control parameter is obtained, if the signal transmission control parameter indicates the reserved subframe included in the radio frame period For sending the through link synchronization signal, the through link synchronization signal is sent in the target subframe.
  • the terminal device when the reference synchronization source of the terminal device is GNSS, if it is determined that the target subframe is a reserved subframe included in the radio frame period, and the acquired signal transmission control parameter indicates that the radio frame
  • the terminal device can re-determine the target subframes from the pre-configured subframes included in the radio frame period, and send the re-determined target subframes. Cut-through link synchronization signal.
  • the terminal device may determine the preconfigured subframe of the first type or the preconfigured subframe of the second type as the target subframe, and The through link synchronization signal is sent on the re-determined target subframe.
  • the terminal device may further determine whether the target subframe is instructed to transmit the direct link according to the signal transmission control parameter. Sync signal.
  • the terminal device executes sending the direct link synchronization signal on the re-determined target subframe.
  • the signaling control parameter includes u bits. Wherein, one bit is used to indicate whether a subframe of a subframe type is used for transmitting the direct link synchronization signal.
  • the signal transmission control parameter includes 2 bits, wherein one bit is used to indicate whether the reserved subframe is used to transmit the direct link synchronization signal, and the other bit is used to indicate whether the preconfigured subframe is used to transmit the direct link. Link synchronization signal.
  • the bit value on the bit when the bit value on the bit is 1, it indicates that the subframe corresponding to the subframe type is used for sending the direct link synchronization signal, and when the bit value on the bit is 0, it indicates the corresponding subframe type.
  • Subframes are not used to transmit cut-through link synchronization signals.
  • it can also be agreed in advance that when the value of the bit on the bit is 0, it indicates that the subframe corresponding to the subframe type is used for sending the direct link synchronization signal, and when the value of the bit on the bit is 1, it indicates the corresponding subframe type.
  • the subframe is not used for sending the direct link synchronization signal, which can be determined according to the actual application scenario, and is not limited here.
  • the terminal device after the terminal device determines the target subframe, it can also monitor the subframe occupancy status of the target subframe to determine whether the target subframe is used for sending the direct link synchronization. Signal. Wherein, when it is determined that other types of data or signals are not sent in the target subframe, the terminal device may perform sending a cut-through link synchronization signal in the target subframe.
  • the terminal device sends the direct link synchronization signal in the target subframe.
  • the terminal device may send the direct link synchronization signal in the target subframe by determining the target subframe from the reserved subframes or preconfigured subframes included in the radio frame period.
  • the embodiments of the present application can solve the problem that a terminal device cannot send a direct link synchronization signal through the PC5 interface based on the Chinese industry standard of LTE-V2X to establish synchronization with other terminal devices. That is to say, the embodiments of the present application increase the diversity of synchronization modes between terminal devices.
  • the embodiment of the present application determines the target subframe from the preconfigured subframe, and Sending the cut-through link synchronization signal in the target subframe can solve the problem that the V2X system cannot work normally because the synchronization cannot be established in this scenario.
  • the embodiment of the present application further expands the establishment of synchronization between the terminal device and other terminal devices. , that is, by sending a direct link synchronization signal in a reserved subframe to establish synchronization between terminal devices.
  • any terminal device for the convenience of description, the second terminal device is taken as an example
  • the second terminal device can send the Internet of Vehicles standard formulated by 3GPP.
  • the terminal equipment that receives the first through link synchronization signal for the convenience of description, the first through link synchronization signal is taken as an example for description
  • the terminal device is described as an example) can maintain synchronization with the second terminal device in the time domain based on the first through link synchronization signal.
  • the first terminal device may also establish synchronization with other terminal devices (eg, a third terminal device) by sending a direct link synchronization signal (for convenience of description, the second direct link synchronization signal is taken as an example for description).
  • a direct link synchronization signal for convenience of description, the second direct link synchronization signal is taken as an example for description.
  • the D-Link synchronization signals eg, the first D-Link synchronization signal and the second D-Link synchronization signal
  • the terminal devices included in the embodiments of the present application are all terminal devices that support the Internet of Vehicles standard formulated by the CCSA.
  • FIG. 4 is another schematic flowchart of a method for sending a direct link synchronization signal provided by an embodiment of the present application.
  • the first terminal device receives a first through link synchronization signal from the second terminal device.
  • the first terminal device may determine the reference synchronization source by searching for the synchronization signal. Specifically, when the first terminal device does not search for a GNSS signal, or when the searched GNSS signal does not meet the signal quality requirements, if the first terminal device can also search for a first through link synchronization signal that meets the signal quality requirements , the first terminal device may determine the second terminal device that sends the first direct link synchronization signal as the reference synchronization source.
  • the first terminal device may monitor the through link synchronization signal in the time domain for a signal monitoring period of 256ms to receive the through link synchronization signal. That is to say, the first terminal device can determine whether a synchronization source has sent a synchronization signal within this period of time by scanning whether there is a synchronization signal in each subframe in 256 ms in sequence.
  • the signal monitoring period may also be set to other durations greater than 256ms, for example, 512ms, etc., which are specifically determined according to actual application scenarios, and are not limited here.
  • the first terminal device can obtain the DFN carried in the first through-link synchronization signal by receiving the first through-link synchronization signal from the second terminal device (for the convenience of description, the first DFN is used as an example to perform description) and a DFN subframe number (for the convenience of description, the first DFN subframe number is used as an example for description).
  • the first DFN and the first DFN subframe number are used to indicate the first subframe.
  • the first subframe may be understood as the subframe when the first terminal device receives the first direct link synchronization signal.
  • the first subframe may be understood as a subframe occupied when the second terminal device sends the first through link synchronization signal.
  • the first terminal device determines a target subframe from the preconfigured subframes included in the radio frame period based on the first subframe.
  • the time domain range of the current radio frame period can be determined according to the first DFN and the first DFN subframe number, and It is synchronized with the second terminal device in the time domain. That is, the first terminal device may use the first DFN and the first DFN subframe number as the starting subframe position for cyclic counting of subsequent subframes (ie, subframes after the first subframe). Further, according to the first subframe, the target subframe may be determined from the preconfigured subframes after the position of the starting subframe.
  • the first terminal device may determine that the target subframe is a preconfigured subframe included in the radio frame period, that is, the first terminal device may The preconfigured subframe of the first type or the preconfigured subframe of the second type after the position of the starting subframe is determined as the target subframe.
  • the first terminal device may determine that the target subframe is the second type of preconfigured subframes included in the radio frame period, that is, the first A terminal device may determine the second type of preconfigured subframes after the starting subframe position as the target subframes.
  • the first terminal device may determine that the target subframe is the first type of preconfigured subframes included in the radio frame period, that is, the first type of preconfigured subframe is included in the radio frame period.
  • a terminal device may determine the first type of preconfigured subframe after the starting subframe position as the target subframe.
  • the first type of preconfigured subframe or the second type of preconfigured subframe after the position of the starting subframe can be The preconfigured subframe of the class is determined as the target subframe. That is to say, the target subframe is a subframe following the first subframe and belonging to the first type of preconfigured subframe or a subframe of the second subframe.
  • the subframes are the second type of preconfigured subframes.
  • the first DFN carried in the first through link synchronization signal is 10
  • the target subframe is a subframe after the first subframe and belongs to the second type of preconfigured subframes.
  • the first terminal device sends a second direct link synchronization signal in the target subframe.
  • the first terminal device may directly send the second direct link synchronization signal on the target subframe.
  • the first terminal device may also acquire the signal sending control parameter, and send the signal according to the signal.
  • the control parameter further determines whether to send a cut-through link synchronization signal in the target subframe.
  • the signal transmission control parameter is obtained, if the signal transmission control parameter indicates the pre-configured subframe included in the radio frame period. If the subframe is configured for sending the direct link synchronization signal, the step of sending the second direct link synchronization signal in the target subframe is performed.
  • the signal transmission control parameters can be preset when the terminal equipment leaves the factory.
  • the signaling control parameters can be programmed in advance or stored in the terminal device.
  • the specific meanings of the signal transmission control parameters with different values may be agreed in advance.
  • the signaling control parameter includes u bits. Wherein, one bit is used to indicate whether a subframe of a subframe type is used for transmitting the direct link synchronization signal.
  • the signal transmission control parameter includes 2 bits, wherein one bit is used to indicate whether the reserved subframe is used to transmit the direct link synchronization signal, and the other bit is used to indicate whether the preconfigured subframe is used to transmit the direct link. Link synchronization signal.
  • the bit value on the bit when the bit value on the bit is 1, it indicates that the subframe corresponding to the subframe type is used for sending the direct link synchronization signal, and when the bit value on the bit is 0, it indicates the corresponding subframe type.
  • Subframes are not used to transmit cut-through link synchronization signals.
  • it can also be agreed in advance that when the value of the bit on the bit is 0, it indicates that the subframe corresponding to the subframe type is used for sending the direct link synchronization signal, and when the value of the bit on the bit is 1, it indicates the corresponding subframe type.
  • the subframe is not used for sending the direct link synchronization signal, which can be determined according to the actual application scenario, and is not limited here.
  • the first terminal device may also monitor the subframe occupancy of the target subframe to determine the target subframe. Whether the subframe is already occupied. It should be understood that when it is determined that the target subframe is not occupied, that is, no other data or signals are sent in the target subframe, the first terminal device may send the second direct link synchronization signal in the target subframe.
  • the target subframe after the target subframe is determined, it may also be determined whether to send the through link synchronization signal according to the signal quality of the first through link synchronization signal.
  • the first terminal device when the through-link synchronization signal received by the first terminal device from the reference synchronization source (ie, the second terminal device) is relatively weak, the first terminal device can establish synchronization with other terminal devices by sending the through-link synchronization signal. For example, when the signal quality of the first through-link synchronization signal is lower than a preset synchronization signal quality threshold, the first terminal device may send the second through-link synchronization signal in the target subframe.
  • the first terminal device may Sending the second cut-through link synchronization signal in the target subframe is performed.
  • the first terminal device can obtain the first DC link by receiving the first DC link synchronization signal from the second terminal device (that is, when the reference synchronization source of the first terminal device is the second terminal device).
  • the link synchronization signal carries the first DFN and the first DFN subframe number, where the first DFN and the first DFN subframe number are used to indicate the first subframe.
  • the first terminal device may determine the target subframe from the preconfigured subframes included in the radio frame period based on the first subframe, and then send the second direct link synchronization signal in the target subframe.
  • the embodiments of the present application can solve the problem that a terminal device cannot send a cut-through link synchronization signal based on the Chinese industry standard of LTE-V2X when another terminal device is used as a reference synchronization source. That is to say, the embodiments of the present application can implement a first terminal device that works under the Internet of Vehicles standard formulated by CCSA, when its reference synchronization source is the second terminal device that works in the same Internet of Vehicles standard (that is, the Internet of Vehicles standard formulated by CCSA). When a terminal device is used, the first terminal device establishes a synchronization scheme with other terminal devices by sending a direct link synchronization signal.
  • FIG. 5 is a schematic structural diagram of a device for sending a direct link synchronization signal according to an embodiment of the present application.
  • the apparatus may be the terminal device described in the first embodiment or the second embodiment, and the device may be used to execute the function of the terminal device described in the first embodiment or the second embodiment.
  • the device includes a processor, a memory, a radio frequency circuit, an antenna, and an input/output device.
  • the processor is mainly used to process the communication protocol and communication data, control the device, execute the software program, process the data of the software program, and the like.
  • the memory is mainly used to store software programs and data.
  • the radio frequency circuit is mainly used for the conversion of baseband signal and radio frequency signal and the processing of radio frequency signal.
  • Antennas are mainly used to send and receive radio frequency signals in the form of electromagnetic waves.
  • Input and output devices such as a touch screen, a display screen, a keyboard, etc., are mainly used for receiving data input by a user using the device and outputting data to the user. It should be noted that, in some scenarios, the communication device may not include an input and output device.
  • the processor When data needs to be sent, the processor performs baseband processing on the data to be sent, and outputs the baseband signal to the radio frequency circuit.
  • the radio frequency circuit performs radio frequency processing on the baseband signal and sends the radio frequency signal through the antenna in the form of electromagnetic waves.
  • the radio frequency circuit receives the radio frequency signal through the antenna, converts the radio frequency signal into a baseband signal, and outputs the baseband signal to the processor, which converts the baseband signal into data and processes the data.
  • FIG. 5 only one memory and processor are shown in FIG. 5 . In an actual device product, there may be one or more processors and one or more memories.
  • the memory may also be referred to as a storage medium or a storage device or the like.
  • the memory may be set independently of the processor, or may be integrated with the processor, which is not limited in this embodiment of the present application.
  • the processor may include a baseband processor and/or a central processing unit.
  • the baseband processor is mainly used to process communication protocols and communication data
  • the central processing unit is mainly used to control the entire terminal device. , execute the software program, and process the data of the software program.
  • the processor in FIG. 5 may integrate the functions of the baseband processor and the central processing unit.
  • the baseband processor and the central processing unit may also be independent processors, interconnected by technologies such as a bus.
  • a terminal device may include multiple baseband processors to adapt to different network standards, a terminal device may include multiple central processors to enhance its processing capability, and various components of the terminal device may be connected through various buses.
  • the above baseband processor may also be expressed as a baseband processing circuit or a baseband processing chip.
  • the above-mentioned central processing unit may also be expressed as a central processing circuit or a central processing chip.
  • the function of processing the communication protocol and communication data may be built in the processor, or may be stored in the storage unit in the form of a software program, and the processor executes the software program to realize the baseband processing function.
  • the antenna and the radio frequency circuit with a transceiver function may be regarded as a transceiver unit of the device, and the processor with a processing function may be regarded as a processing unit of the device.
  • the apparatus includes a transceiver unit 310 and a processing unit 320 .
  • the transceiving unit may also be referred to as a transceiver, a transceiver, a transceiving device, and the like.
  • the processing unit 320 may also be referred to as a processor, a processing board, a processing module, a processing device, or the like.
  • the device for implementing the receiving function in the transceiver unit 310 may be regarded as a receiving unit, and the device for implementing the transmitting function in the transceiver unit 310 may be regarded as a transmitting unit, that is, the transceiver unit 310 includes a receiving unit and a transmitting unit.
  • the receiving unit may also be sometimes referred to as a receiver, a receiver, or a receiving circuit or the like.
  • the transmitting unit may also sometimes be referred to as a transmitter, a transmitter, or a transmitting circuit, or the like.
  • the transceiver unit 310 is configured to perform the process of detecting and receiving the GNSS signal or the through-link synchronization signal and the step of sending the through-link synchronization signal described in the first embodiment or the second embodiment.
  • the processing unit 320 is configured to perform the steps of determining the target subframe from the radio frame period in the first embodiment or the second embodiment.
  • FIG. 6 is another schematic structural diagram of an apparatus for sending a direct link synchronization signal according to an embodiment of the present application.
  • the apparatus may be the terminal device in the first embodiment or the second embodiment, and the apparatus may be used to implement the communication method implemented by the terminal device.
  • the apparatus includes: a processor 41 , a memory 42 , and a transceiver 43 .
  • the memory 42 includes, but is not limited to, RAM, ROM, EPROM or CD-ROM, and the memory 42 is used to store related instructions and data.
  • the memory 42 stores the following elements, executable modules or data structures, or a subset thereof, or an extended set thereof:
  • Operation instructions including various operation instructions, which are used to realize various operations.
  • Operating System Includes various system programs for implementing various basic services and handling hardware-based tasks.
  • the transceiver 43 may be a communication module or a transceiver circuit. Application In the embodiments of the present application, the transceiver 43 is configured to perform operations such as receiving a GNSS signal or a direct link synchronization signal, and sending a direct link synchronization signal involved in the foregoing embodiments.
  • the processor 41 may be a controller, CPU, general purpose processor, DSP, ASIC, FPGA or other programmable logic device, transistor logic device, hardware component or any combination thereof. It may implement or execute various exemplary logical blocks, modules and circuits described in connection with the disclosure of the embodiments of this application.
  • the processor 41 can 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, and the like.
  • various components of the device may be coupled together through a bus system, and the line system may include a power bus, a control bus, a status signal bus, and the like in addition to a data bus.
  • Embodiments of the present application further provide a computer-readable medium on which a computer program is stored, and when the computer program is executed by a computer, implements the methods or steps performed by the terminal device in the foregoing embodiments.
  • Embodiments of the present application further provide a computer program product, which implements the methods or steps performed by the terminal device in the foregoing embodiments when the computer program product is executed by a computer.
  • An embodiment of the present application further provides an apparatus, and the apparatus may be the terminal device in the foregoing embodiment.
  • the apparatus includes a processor and an interface.
  • the processor is configured to execute the methods or steps executed by the terminal device in the foregoing embodiments.
  • the above-mentioned terminal device may be a chip
  • the above-mentioned processor may be implemented by hardware or software.
  • the processor When implemented by hardware, the processor may be a logic circuit, an integrated circuit, or the like.
  • the processor can be a general-purpose processor, and can be implemented by reading software codes stored in a memory, which can be integrated in the processor or located outside the processor and exist independently.
  • the processor in this embodiment of the present application may be an integrated circuit chip, which has a signal processing capability.
  • each step of the above method embodiments may be completed by a hardware integrated logic circuit in a processor or an instruction in the form of software.
  • the above-mentioned processor can be a general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), an off-the-shelf programmable gate array (field programmable gate array, FPGA) or other Programming logic devices, discrete gate or transistor logic devices, discrete hardware components.
  • DSP digital signal processor
  • ASIC application specific integrated circuit
  • FPGA field programmable gate array
  • Programming logic devices discrete gate or transistor logic devices, discrete hardware components.
  • the present application also provides a communication system, which includes the aforementioned one or more terminal devices.
  • the foregoing method embodiments may be implemented in whole or in part by software, hardware, firmware, or any combination thereof.
  • software When implemented in software, it can be implemented in whole or in part in the form of a computer program product.
  • the computer program product described above includes one or more computer instructions. When the above-mentioned computer instructions are loaded and executed on the computer, all or part of the above-mentioned processes or functions according to the embodiments of the present application are generated.
  • the aforementioned computer may be a general purpose computer, a special purpose computer, a computer network, or other programmable devices.
  • the above-mentioned computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the above-mentioned computer instructions may be transmitted from a website site, computer, server or data center via wired communication. (e.g. coaxial cable, fiber optic, digital subscriber Line (DSL) or wireless (e.g. infrared, wireless, microwave, etc.) to another website site, computer, server or data center.
  • the above computer readable storage The medium can be any available medium that can be accessed by a computer or a data storage device that contains one or more of the available media integration servers, data centers, etc.
  • the aforementioned available media can be magnetic media (eg, floppy disks, hard disks, magnetic tapes), optical media (For example, a high-density digital video disc (DVD), or a semiconductor medium (for example, a solid state disk (SSD), etc.).
  • magnetic media eg, floppy disks, hard disks, magnetic tapes
  • optical media For example, a high-density digital video disc (DVD), or a semiconductor medium (for example, a solid state disk (SSD), etc.
  • SSD solid state disk
  • the processor in this embodiment of the present application may be an integrated circuit chip, which has a signal processing capability.
  • each step of the above method embodiments may be completed by a hardware integrated logic circuit in a processor or an instruction in the form of software.
  • the above-mentioned processor can be a general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), an off-the-shelf programmable gate array (field programmable gate array, FPGA) or other Programming logic devices, discrete gate or transistor logic devices, discrete hardware components.
  • DSP digital signal processor
  • ASIC application specific integrated circuit
  • FPGA field programmable gate array
  • Programming logic devices discrete gate or transistor logic devices, discrete hardware components.
  • a general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
  • the steps of the method disclosed in conjunction with the embodiments of the present application may be directly embodied as executed by a hardware decoding processor, or executed by a combination of hardware and software modules in the decoding processor.
  • the software modules may be located in random access memory, flash memory, read-only memory, programmable read-only memory or electrically erasable programmable memory, registers and other storage media mature in the art.
  • the storage medium is located in the memory, and the processor reads the information in the memory, and completes the steps of the above method in combination with its hardware.
  • the memory in this embodiment of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memory.
  • the non-volatile memory may be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically programmable Erase programmable read-only memory (electrically EPROM, EEPROM) or flash memory.
  • Volatile memory may be random access memory (RAM), which acts as an external cache.
  • RAM random access memory
  • DRAM dynamic random access memory
  • SDRAM synchronous DRAM
  • SDRAM double data rate synchronous dynamic random access memory
  • ESDRAM enhanced synchronous dynamic random access memory
  • SLDRAM synchronous link dynamic random access memory
  • direct rambus RAM direct rambus RAM

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Abstract

本申请实施例公开了一种直通链路同步信号发送方法，可解决支持CCSA制定的车联网标准的终端设备，无法通过PC5接口发送直通链路同步信号以建立与其他终端设备之间同步的问题。该方法包括：终端设备从无线帧周期包括的预留子帧或预配置子帧中确定出目标子帧。其中，无线帧周期包括10240个子帧，10240个子帧中包括40个预留子帧，预配置子帧为无线帧周期中由子帧配置位图中比特值为0的一个比特位所指示的子帧。终端设备在目标子帧中发送直通链路同步信号。其中，该直通链路同步信号包括PSSS、SSSS、PSBCH和DMRS。

Description

直通链路同步信号的发送方法和装置 技术领域
本申请涉及通信技术领域，尤其涉及一种直通链路同步信号的发送方法和装置。
背景技术
在R14版本(Release 14)的标准中，第三代合作伙伴计划(the 3rd generation partnership project，3GPP)制定了基于长期演进(long term evolution，LTE)的车联网(vehicle to everything，V2X)技术的直通链路(sidelink)同步信号的发送和接收流程，其中，定义了用于发送直通链路同步信号的子帧的子帧位置通过三个预配置参数syncOffsetIndicator1，syncOffsetIndicator2，以及syncOffsetIndicator3进行指示。然而，在中国通信标准化协会(china communications standards association，CCSA)制定的LTE-V2X中国行业标准中，删除了3GPP中定义的直通链路同步信号的发送和接收流程，同时也删除了预配置参数syncOffsetIndicator1，syncOffsetIndicator2，以及syncOffsetIndicator3。因此，基于LTE-V2X的中国行业标准，V2X终端设备无法通过PC5接口发送直通链路同步信号来实现V2X终端设备之间的同步。
发明内容
本申请实施例提供了一种直通链路同步信号的发送方法和装置，可解决基于LTE-V2X的中国行业标准，终端设备无法通过PC5接口发送直通链路同步信号以建立与其他终端设备之间同步的问题。
第一方面，本申请实施例提供了一种直通链路同步信号的发送方法。该方法包括：终端设备从无线帧周期包括的预留子帧或预配置子帧中确定出目标子帧，并在目标子帧中发送直通链路同步信号。其中，无线帧周期包括10240个子帧，10240个子帧中包括40个预留子帧，预配置子帧为无线帧周期中由子帧配置位图中比特值为0的一个比特位所指示的子帧。直通链路同步信号包括直通链路主同步信号PSSS、直通链路辅同步信号SSSS、物理直通链路广播信道PSBCH和解调参考信号DMRS。也就是说，本申请实施例中的直通链路同步信号符合3GPP制定的车联网标准，其具体包括4部分，分别为PSSS、SSSS、PSBCH和DMRS，其中各部分的格式和内容可参见3GPP中的定义。
在本申请实施例中，通过从无线帧周期包括的预留子帧或预配置子帧中确定出目标子帧，并在目标子帧中发送直通链路同步信号，可解决基于LTE-V2X的中国行业标准，终端设备无法通过PC5接口发送直通链路同步信号以建立与其他终端设备之间同步的问题。
结合第一方面，在一种可行的实现方式中，无线帧周期中的预留子帧的直接帧号DFN f和DFN子帧号s满足：
Figure PCTCN2020106444-appb-000001
s＝i-f×10，i＝256×m；
其中，m为整数且0≤m≤39。
结合第一方面，在一种可行的实现方式中，无线帧周期中除40个预留子帧之外的10200 个子帧中每连续的100个子帧由一个子帧配置位图指示，子帧配置位图包括100个比特位，一个比特位指示一个子帧，其中，每连续的100个子帧中包括由子帧配置位图中比特值为0的一个比特位所指示的一个预配置子帧。
结合第一方面，在一种可行的实现方式中，当终端设备获取不到全球导航卫星系统GNSS信号时，目标子帧为无线帧周期包括的预配置子帧，且目标子帧的DFN f和DFN子帧号s满足：
Figure PCTCN2020106444-appb-000002
s＝i-f×10，
Figure PCTCN2020106444-appb-000003
n为小于102的奇数；
其中，k为子帧配置位图中比特值为0的一个比特位对应的比特位序号。应当理解的是，当终端设备获取不到GNSS信号时，可理解为该终端设备没有参考同步源，即终端设备的参考同步源为空，因此终端设备进入自同步状态。具体地，终端设备获取不到GNSS信号可包括2种情况，一种情况为终端设备没有接收到GNSS信号，另一种情况为终端设备可接收到GNSS信号，但所接收的GNSS信号不符合信号质量要求。
在本申请实施例中，当终端设备获取不到GNSS信号时，通过将预配置子帧确定为目标子帧，并在目标子帧上发送直通链路同步信号，可解决基于LTE-V2X的中国行业标准，当终端设备不能接收到符合信号质量要求的GNSS信号时，终端设备之间无法建立同步的问题。
结合第一方面，在一种可行的实现方式中，当终端设备获取不到GNSS信号时，目标子帧为无线帧周期包括的预配置子帧，且目标子帧的DFN f和DFN子帧号s满足：
Figure PCTCN2020106444-appb-000004
s＝i-f×10，
Figure PCTCN2020106444-appb-000005
n为小于102的偶数；
其中，k为子帧配置位图中比特值为0的一个比特位对应的比特位序号。
在本申请实施例中，当终端设备获取不到GNSS信号时，通过将预配置子帧确定为目标子帧，并在目标子帧上发送直通链路同步信号，可解决基于LTE-V2X的中国行业标准，当终端设备不能接收到符合信号质量要求的GNSS信号时，终端设备之间无法建立同步的问题。
结合第一方面，在一种可行的实现方式中，当终端设备获取到GNSS信号时，目标子帧为无线帧周期中包括的预留子帧。应当理解，当终端设备获取到GNSS信号时，可理解为终端设备的参考同步源为GNSS。
在本申请实施例中，当终端设备获取到GNSS信号时，通过将无线帧周期中包括的预留子帧确定为目标子帧，并在目标子帧中发送直通链路同步信号，可解决基于LTE-V2X的中国行业标准，终端设备只能接收GNSS信号，无法发送直通链路同步信号的问题。
结合第一方面，在一种可行的实现方式中，当终端设备确定目标子帧为预配置子帧时，终端设备在目标子帧中发送直通链路同步信号之前，终端设备还可以获取信号发送控制参数。其中，若信号发送控制参数指示无线帧周期中包括的预配置子帧用于发送直通链路同步信号，则终端设备可执行在目标子帧中发送直通链路同步信号的步骤。
在本申请实施例中，通过设置信号发送控制参数，可提高终端设备发送直通链路同步信号时的可控性。
结合第一方面，在一种可行的实现方式中，当终端设备确定目标子帧为预留子帧时，终端设备在目标子帧中发送直通链路同步信号之前，终端设备还可以获取信号发送控制参数。若信号发送控制参数指示无线帧周期中包括的预留子帧用于发送直通链路同步信号，则执行在目标子帧中发送直通链路同步信号的步骤。
结合第一方面，在一种可行的实现方式中，当终端设备确定目标子帧为预留子帧时，若获取到的信号发送控制参数指示无线帧周期中的预留子帧不用于发送直通链路同步信号时，终端设备还可以从无线帧周期包括的预配置子帧中重新确定出目标子帧，并在重新确定出的目标子帧上发送直通链路同步信号。其中，重新确定出的目标子帧的DFN f和DFN子帧号s满足：
Figure PCTCN2020106444-appb-000006
s＝i-f×10，
Figure PCTCN2020106444-appb-000007
n为小于102的奇数；
其中，k为子帧配置位图中比特值为0的一个比特位对应的比特位序号。
在本申请中，当信号发送控制参数指示无线帧周期中的预留子帧不用于发送直通链路同步信号时，终端设备从无线帧周期包括的预配置子帧中重新确定出目标子帧，并在重新确定出的目标子帧上发送直通链路同步信号，可提高直通链路同步信号的发送成功率。
结合第一方面，在一种可行的实现方式中，当终端设备确定目标子帧为预留子帧时，若获取到的信号发送控制参数指示无线帧周期中的预留子帧不用于发送直通链路同步信号时，终端设备可从无线帧周期包括的预配置子帧中重新确定出目标子帧，并在重新确定出的目标子帧上发送直通链路同步信号。其中，重新确定出的目标子帧的DFN f和DFN子帧号s满足：
Figure PCTCN2020106444-appb-000008
s＝i-f×10，
Figure PCTCN2020106444-appb-000009
n为小于102的偶数；
其中，k为子帧配置位图中比特值为0的一个比特位对应的比特位序号。
在本申请中，当信号发送控制参数指示无线帧周期中的预留子帧不用于发送直通链路同步信号时，终端设备从无线帧周期包括的预配置子帧中重新确定出目标子帧，并在重新确定出的目标子帧上发送直通链路同步信号，可提高直通链路同步信号的发送成功率。
第二方面，本申请实施例提供了一种直通链路同步信号的发送方法。该方法包括：第一终端设备从第二终端设备接收第一直通链路同步信号。其中，第一直通链路同步信号中携带第一DFN和第一DFN子帧号，第一DFN和第一DFN子帧号用于指示第一子帧。第一终端设备基于第一子帧从无线帧周期包括的预配置子帧中确定出目标子帧，并在目标子帧中发送第二直通链路同步信号。其中，无线帧周期包括10240个子帧，10240个子帧中包括40个预留子帧，预配置子帧为无线帧周期中由子帧配置位图中比特值为0的一个比特位所指示的子帧。其中，本申请实施例中所涉及的直通链路同步信号(第一直通链路同步信号和第二直通链路同步信号)皆符合3GPP制定的车联网标准，其具体包括4部分，分别为PSSS、SSSS、PSBCH和DMRS，其中各部分的格式和内容可参见3GPP中的定义。
在本申请实施例中，通过从第二终端设备接收第一直通链路同步信号，根据第一直通链路同步信号中携带的第一DFN和第一DFN子帧号从预配置子帧中确定出目标子帧，以在目标子帧中发送第二直通链路同步信号，解决了基于LTE-V2X的中国行业标准，终端设 备以另一终端设备作为参考同步源时，如何发送直通链路同步信号的问题。
结合第二方面，在一种可行的实现方式中，第一终端设备可以256ms为信号监听周期在时域上监听直通链路同步信号以接收直通链路同步信号。
结合第二方面，在一种可行的实现方式中，无线帧周期中的预留子帧的DFN f和DFN子帧号s满足：
Figure PCTCN2020106444-appb-000010
s＝i-f×10，i＝256×m；
其中，m为整数且0≤m≤39。
结合第二方面，在一种可行的实现方式中，无线帧周期中除40个预留子帧之外的10200个子帧中每连续的100个子帧由一个子帧配置位图指示，子帧配置位图包括100个比特位，一个比特位指示一个子帧，其中，每连续的100个子帧中包括由子帧配置位图中比特值为0的一个比特位所指示的一个预配置子帧。
结合第二方面，在一种可行的实现方式中，无线帧周期包括的预配置子帧中包括第一类预配置子帧和第二类预配置子帧。第一类预配置子帧的DFN f和DFN子帧号s满足：
Figure PCTCN2020106444-appb-000011
s＝i-f×10，
Figure PCTCN2020106444-appb-000012
n为奇数且0≤n≤101；
第二类预配置子帧的DFN f和DFN子帧号s满足：
Figure PCTCN2020106444-appb-000013
s＝i-f×10，
Figure PCTCN2020106444-appb-000014
n为偶数且0≤n≤101；
其中，k为子帧配置位图中比特值为0的一个比特位对应的比特位序号。具体地，当第一子帧为无线帧周期包括的第一类预配置子帧时，目标子帧为无线帧周期包括的第二类预配置子帧。当第一子帧为无线帧周期包括的第二类预配置子帧时，目标子帧为无线帧周期包括的第一类预配置子帧。
在本申请实施例中，通过选择与第一子帧不同的预配置子帧作为目标子帧，可降低子帧间的相互干扰，提高直通链路同步信号的发送成功率。
结合第二方面，在一种可行的实现方式中，当第一子帧为无线帧周期包括的预留子帧时，目标子帧为无线帧周期中的第一类预配置子帧。
结合第二方面，在一种可行的实现方式中，当第一子帧为无线帧周期包括的预留子帧时，目标子帧为无线帧周期中的第二类预配置子帧。
结合第二方面，在一种可行的实现方式中，第一终端设备还可以获取信号发送控制参数，若信号发送控制参数指示无线帧周期中包括的预配置子帧用于发送直通链路同步信号，则执行在目标子帧中发送第二直通链路同步信号的步骤。
第三方面，本申请实施例提供了一种直通链路同步信号的发送装置。该发送装置可为终端设备本身，也可为终端设备内部的如芯片等元件或者模块。该通信装置包括用于执行上述第一方面和/或第二方面的任意一种可能的实现方式所提供的直通链路同步信号的发送方法的单元，因此也能是实现第一方面和/或第二方面提供的直通链路同步信号的发送方法所具备的有益效果(或者优点)。
第四方面，本申请实施例提供了一种直通链路同步信号的发送装置，该发送装置可为 终端设备。该通信装置包括至少一个存储器、收发器以及处理器。其中，该处理器和收发器用于调用存储器存储的代码执行上述第一方面和/或第二方面中任意一种可行的实现方式所提供的直通链路同步信号的发送方法。
第五方面，本申请实施例提供了一种直通链路同步信号的发送装置，该通信装置可为终端设备。该通信装置包括：至少一个处理器和接口电路。该接口电路用于接收代码指令并传输至该处理器。该处理器用于运行上述代码指令以实现上述第一方面和/或第二方面中任意一种可行的实现方式所提供的直通链路同步信号的发送方法，也能实现上述第一方面和/或第二方面提供的直通链路同步信号的发送方法所具备的有益效果(或者优点)。
第六方面，本申请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中存储有指令，当该指令在计算机上运行时，实现上述第一方面和/或第二方面中任意一种可行的实现方式所提供的直通链路同步信号的发送方法，也能实现上述第一方面和/或第二方面提供的直通链路同步信号的发送方法所具备的有益效果(或者优点)。
第七方面，本申请实施例提供了一种包含指令的计算机程序产品，当该计算机程序产品在计算机上运行时，使得计算机执行上述第一方面和/或第二方面提供的直通链路同步信号的发送方法，也能实现第一方面和/或第二方面提供的直通链路同步信号的发送方法所具备的有益效果。
采用本申请实施例提供的方法，可解决基于LTE-V2X的中国行业标准，终端设备无法通过PC5接口发送直通链路同步信号以建立与其他终端设备之间同步的问题。
附图说明
图1是本申请实施例提供的V2X通信系统的系统架构示意图；
图2是本申请实施例提供的无线帧周期的结构示意图；
图3是本申请实施例提供的直通链路同步信号的发送方法的一流程示意图；
图4是本申请实施例提供的直通链路同步信号的发送方法的另一流程示意图；
图5是本申请实施例提供的一种直通链路同步信号的发送装置一结构示意图；
图6是本申请实施例提供的一种直通链路同步信号的发送装置又一结构示意图。
具体实施方式
随着智能化时代的到来，车联网技术已经成为智能交通系统(intelligent transportation systems，ITS)的关键技术之一。其中，V2X通信技术作为车联网领域的重要通信技术之一，其主要包括车与车(vehicle tovehicle，V2V)之间的通信、车与基建/网络(vehicle to infrastructure/network，V2I/N)之间的通信、以及车与个人携带的装置(vehicle to pedestrian，V2P)之间的通信等。例如，V2P之间的通信可以为车载终端与行人、司机或者乘客的手持终端之间的通信等，在此不做限制。目前，在智能交通、无人驾驶等领域，V2X通信技术得到了越来越广泛的应用。
如图1所示，图1是本申请实施例提供的V2X通信系统的系统架构示意图。如图1所示，V2X通信系统可包括全球导航卫星系统(global navigation satellite system，GNSS)、车载单元(on board unit，OBU)、路侧单元(road side unit，RSU)和移动终端等。其中，可将支持V2X通信的各类终端设备(例如OBU、RSU和移动终端等)统称为V2X终端设备，为 方便描述，简称终端设备。应当理解的是，上述终端设备可以是芯片，也可以是包含芯片的用户设备。其中，当终端设备为芯片时，该芯片可包括处理器和接口。当终端设备为包含芯片的用户设备时，终端设备可以是OBU、RSU、移动终端、订户单元(subscriber unit)、订户站(subscriber station)、移动站(mobile station)、移动台(mobile)、远程站(remote station)、接入点(access point，AP)、远程终端(remote terminal)、接入终端(access terminal)、用户终端(user terminal)、用户代理(user agent)、或用户装备(user device)等。其中，移动终端可包括移动电话(或称为“蜂窝”电话)，计算机、平板电脑、智能手机、个人数码助理(personal digital assistant，PDA)、移动互联网设备(mobile Internet device，MID)和智能穿戴式设备等。或者，移动终端也可以是便携式、袖珍式、手持式、计算机内置的或者车载的移动装置等，在此不做限制。在本申请提供的V2X通信系统中，同一类型的终端设备的数量可以是一个也可以是多个，在此不做限制，例如，图1中的OBU可包括OBU1和OBU2。
在本申请提供的V2X通信系统中，GNSS可包括美国的全球定位系统(global positioning system，GPS)、俄罗斯的格洛纳斯卫星导航系统(global navigation satellite system，GLONASS)、欧盟的伽利略卫星导航系统(galileo satellite navigation system，GALILEO)、以及中国的北斗卫星导航系统(beidou navigation satellite system，BDS)等一种或多种定位系统。其中，GNSS可以与各终端设备进行通信，各终端设备之间也可以互相通信。例如，如图1所示，GNSS可以与各OBU和移动终端进行通信，各OBU可以与RSU和移动终端进行通信，各个OBU之间也可以相互通信等。
应当理解的是，V2X通信主要涉及两种通信接口，分别为PC5接口和Uu接口。其中，基于PC5接口的V2X通信是终端设备之间的直连通信或侧行通信，其通信链路通常被定义为侧行链路，或者也可以称为直连链路或直通链路或边链路。也就是说，基于PC5接口的V2X通信是终端设备之间的直接通信，其无需通过网络设备进行转发。而基于Uu接口的V2X通信则需要发送方终端设备通过Uu接口将V2X数据发送至网络设备，并由网络设备发送至V2X应用服务器进行处理后，再由V2X应用服务器下发至接收方终端设备。应当理解的是，本申请可适用于各个终端设备之间进行侧行通信的场景。其中，本申请中所涉及的侧行通信可以是一对终端设备之间进行的单播通信，也可以是一个终端设备与一组终端设备之间进行的多播或组播通信，或者还可以是一个终端设备与不限定个数的终端设备之间进行的广播通信等，具体根据实际应用场景确定，在此不做限制。
不难理解的是，当终端设备之间进行V2X通信时，为保证通信质量，终端设备之间保持同步是提高终端设备之间通信效率的基本要求之一。例如，假设终端设备为设置在车辆上的车载单元(如图1中的OBU1和OBU2)，则当车载单元随着车辆高速移动时，如图1所示，当OBU1和OBU2之间相互运动时，为了保证OUB1和OBU2之间的可靠通信，OBU1和OBU2需要进行同步。然而，在CCSA制定的LTE-V2X中国行业标准中，删除了3GPP中定义的直通链路同步信号的发送和接收流程，同时也删除了预配置参数syncOffsetIndicator1，syncOffsetIndicator2，以及syncOffsetIndicator3。因此，基于LTE-V2X的中国行业标准，终端设备无法通过发送直通链路同步信号来建立终端设备之间的同步。也就是说，当终端设备使用CCSA制定的车联网标准进行V2X通信时，该终端设备无法通 过PC5接口发送直通链路同步信号来建立终端设备之间的同步，特别是当V2X通信系统中的各终端设备不能接收到符合信号质量要求的GNSS信号时，将导致各终端设备之间无法同步，进而导致V2X通信系统无法正常工作。基于此，本申请提供了一种直通链路同步信号发送方法，可在现有CCSA制定的LTE-V2X中国行业标准下，确定出用于发送直通链路同步信号的目标子帧，并通过在目标子帧中发送直通链路同步信号以实现终端设备之间的同步。
为方便理解，下面将对本申请提供的直通链路同步信号发送方法中涉及的部分概念或内容作简单介绍：
1、无线帧周期
请参见图2，图2是本申请实施例提供的无线帧周期的结构示意图。如图2所示，每个无线帧周期为10240ms，即每个无线帧周期中包括10240个子帧，其中1个子帧＝1ms。应当理解的是，由于每个无线帧包括10个子帧，因此，一个无线帧周期可包括1024个无线帧。如图2所示，一个无线帧可由一个直接帧号(direct frame number，DFN)指示，因此，每个无线帧周期中DFN的取值范围为0～1023。其中，每个无线帧中包括的每个子帧可由DFN子帧号指示，因此，每个无线帧中DFN子帧号的取值范围为0～9。也就是说，每个无线帧周期中包括的每个子帧可由DFN和DFN子帧号共同指示。
2、预留子帧
在CCSA制定的LTE-V2X的中国行业标准中，规定了一个无线帧周期中共包括40个预留子帧。其中，该40个预留子帧的DFN f和DFN子帧号s满足：
Figure PCTCN2020106444-appb-000015
s＝i-f×10，i＝256×m
其中，m为整数且0≤m≤39。也就是说，每个无线帧周期中的第0个子帧(即DFN为0，DFN子帧号为0的子帧)，第256个子帧(即DFN为25，DFN子帧号为6的子帧)，第512个子帧(即DFN为51，DFN子帧号为2的子帧)，……，第9984个子帧(即DFN为998，DFN子帧号为4的子帧)皆为预留子帧。或者，也可以说这些子帧的子帧类型为预留子帧。
3、子帧配置位图
在CCSA制定的LTE-V2X的中国行业标准中，还规定了无线帧周期中除40个预留子帧之外的10200个子帧中每连续的100个子帧由一个子帧配置位图bitmap指示。其中，子帧配置位图包括100个比特位，即子帧配置位图的长度为100bit，一个比特位指示一个子帧。也就是说，每个无线帧周期中除40个预留子帧之外的10200个子帧一共可由102个相同的子帧配置位图指示。
具体地，每个无线帧周期中的第1个子帧(即DFN为0，DFN子帧号为1的子帧)～第100个子帧(即DFN为10，DFN子帧号为0的子帧)可由一个子帧配置位图指示，每个无线帧周期中的第101个子帧(即DFN为10，DFN子帧号为1的子帧)～第200个子帧(即DFN为20，DFN子帧号为0的子帧)可由一个上述子帧配置位图指示，每个无线帧周期中的第201个子帧(即DFN为20，DFN子帧号为1的子帧)～第255个子帧(即DFN为25，DFN子帧号为5的子帧)，第257个子帧(即DFN为25，DFN子帧号为7的子帧) ～第301个子帧(即DFN为30，DFN子帧号为1的子帧)可由一个上述子帧配置位图指示，以此类推，每个无线帧周期中的第10140个子帧(即DFN为1014，DFN子帧号为0的子帧)～第10239个子帧(即DFN为1023，DFN子帧号为9的子帧)可由一个上述子帧配置位图指示。应当理解的是，子帧配置位图中一个比特位对应一个比特位序号，因此，100个比特位对应的比特位序号的取值范围为0～99。通常来说，每个比特位上包括一个比特值，且每个比特位上的比特值的取值可以为0或1。
4、预配置子帧
在本申请中，每连续的100个子帧中包括由子帧配置位图中比特值为0的一个比特位所指示的一个预配置子帧。也就是说，预配置子帧为子帧配置位图中比特值为0的一个比特位对应的子帧。由此可知，一个无线帧周期中共包括102个预配置子帧。
应当理解的是，当子帧配置位图中包括1个比特值为0的比特位和99个比特值为1的比特位时，该1个比特值为0的比特位所对应的子帧即为预配置子帧。举例来说，假设子帧配置位图中共包括1个比特值为0的比特位，且上述1个比特值为0的比特位对应的比特位序号为0。因此，可将每个无线帧周期中比特位序号0对应的子帧确定为预配置子帧。可选的，当子帧配置位图中包括n个比特值为0的比特位和(100-n)个比特值为1的比特位时，可从n个比特值为0的比特位中随机确定一个比特值为0的比特位对应的子帧作为预配置子帧，其中n为大于1且小于100的整数。例如，可将n个比特值为0的比特位中，比特位序号最小的比特位对应的子帧确定为预配置子帧，或者，也可以将n个比特值为0的比特位中，比特位序号最大的比特位对应的子帧确定为预配置子帧，具体可根据实际需要进行事先约定，在此不做限制。
举例来说，假设子帧配置位图中共包括3个比特值为0的比特位，其中，上述3个比特值为0的比特位分别对应的比特位序号为0，1，2。假设事先约定预配置子帧为比特位序号最小的比特位对应的子帧，则可将无线帧周期中比特位序号0对应的子帧确定为预配置子帧。假设事先约定预配置子帧为比特位序号最大的比特位对应的子帧，则可将无线帧周期中比特位序号2对应的子帧确定为预配置子帧。
其中，无线帧周期中包括的预配置子帧的DFN和DFN子帧号用公式表述时，其DFN f和DFN子帧号s满足：
Figure PCTCN2020106444-appb-000016
s＝i-f×10，
Figure PCTCN2020106444-appb-000017
其中，n为整数且0≤n≤101，k为子帧配置位图中比特值为0的一个比特位对应的比特位序号。
在本申请中，根据各预配置子帧在无线帧周期中的出现位置的不同，可将预配置子帧划分为第一类预配置子帧和第二类预配置子帧。其中，第一类预配置子帧和第二类预配置子帧在无线帧周期中交替出现。由此可知，无线帧周期中共包括51个第一类预配置子帧和51个第二类预配置子帧。
举例来说，假设无线帧周期中的第1个子帧～第100个子帧中包括的一个预配置子帧为第一类预配置子帧，则该无线帧周期中的第101个子帧～第200个子帧中包括的一个预配置子帧为第二类预配置子帧，则该无线帧周期中的第201个子帧～第255个子帧，第257个子 帧～第301个子帧中包括的一个预配置子帧为第一类预配置子帧，以此类推，该无线帧周期中第10140个子帧～第10239个子帧中包括的一个预配置子帧为第二类预配置子帧。
又举例来说，假设无线帧周期中的第1个子帧～第100个子帧中包括的一个预配置子帧为第二类预配置子帧，则该无线帧周期中的第101个子帧～第200个子帧中包括的一个预配置子帧为第一类预配置子帧，则该无线帧周期中的第201个子帧～第255个子帧，第257个子帧～第301个子帧中包括的一个预配置子帧为第二类预配置子帧，以此类推，该无线帧周期中的第10140个子帧～第10239个子帧中包括的一个预配置子帧为第一类预配置子帧。
其中，当无线帧周期中的第1个子帧～第100个子帧中包括的预配置子帧为第二类预配置子帧时，无线帧周期中包括的51个第一类预配置子帧的DFN f和DFN子帧号s用公式表述时，满足：
Figure PCTCN2020106444-appb-000018
s＝i-f×10，
Figure PCTCN2020106444-appb-000019
n为奇数且0≤n≤101；
相应地，无线帧周期中包括的51个第二类预配置子帧的DFN f和DFN子帧号s用公式表述时，满足：
Figure PCTCN2020106444-appb-000020
s＝i-f×10，
Figure PCTCN2020106444-appb-000021
n为偶数且0≤n≤101；
其中，k为子帧配置位图中比特值为0的一个比特位对应的比特位序号。
可选的，当无线帧周期中的第1个子帧～第100个子帧中包括的预配置子帧为第一类预配置子帧时，无线帧周期中包括的51个第一类预配置子帧的DFN f和DFN子帧号s用公式表述时，满足：
Figure PCTCN2020106444-appb-000022
s＝i-f×10，
Figure PCTCN2020106444-appb-000023
n为偶数且0≤n≤101；
相应地，无线帧周期中包括的51个第二类预配置子帧的DFN f和DFN子帧号s用公式表述时，满足：
Figure PCTCN2020106444-appb-000024
s＝i-f×10，
Figure PCTCN2020106444-appb-000025
n为奇数且0≤n≤101；
其中，k为子帧配置位图中比特值为0的一个比特位对应的比特位序号。
为方便描述，以下本申请实施例皆以无线帧周期中的第1个子帧～第100个子帧中包括的预配置子帧为第二类预配置子帧为例进行说明。
下面将结合图3至图6对本申请实施例提供的方法及相关装置分别进行详细说明。
实施例一
请参见图3，图3是本申请实施例提供的直通链路同步信号的发送方法的一流程示意图。
S101、终端设备从无线帧周期包括的预留子帧或预配置子帧中确定目标子帧。
在一些可行的实施方式中，终端设备可通过搜索或检测同步信号来确定参考同步源。其中，当终端设备搜索或检测到的同步信号满足信号质量要求时，则可将发送该同步信号的同步源确定为参考同步源。例如，假设终端设备为设置在车辆上的OBU，则当终端设备随着车辆移动或停留在空旷路段时，若终端设备搜索或检测到的GNSS信号满足信号质量 要求，则终端设备可确定参考同步源为GNSS。应当理解的是，信号质量可基于信号强度、信号接收功率、或信噪比等参数进行度量，在此不做限制。其中，终端设备为支持CCSA制定的车联网标准的终端设备。也就是说，本申请实施例中的终端设备为以CCSA制定的车联网标准进行V2X通信的终端设备。
可选的，在一些可行的实施方式中，当终端设备获取不到GNSS信号时，可确定参考同步源为空，此时终端设备进入自同步状态。不难理解的是，终端设备获取不到GNSS信号可包括两种情况，一种情况是终端设备没有搜索或检测到GNSS信号，另一种情况是终端设备可以搜索或检测到GNSS信号，但GNSS信号的信号质量不满足信号质量要求。例如，假设终端设备为设置在车辆上的OBU，则当终端设备随着车辆移动从GNSS信号强的空旷地带进入隧道或者峡谷或者地下停车场中时，由于障碍物的严重遮挡，终端设备可能搜索或检测不到满足信号质量要求的GNSS信号。因此，终端设备可在搜索或检测不到满足信号质量要求的GNSS信号，进入自同步状态。
具体地，当终端设备的参考同步源为GNSS时，终端设备可根据GNSS发送的GNSS信号确定DFN和DFN子帧号。其中，GNSS信号中包括定时信息，定时信息中包括当前世界统一时间(coordinated universal time，UTC)。终端设备根据定时信息可通过以下公式分别计算出DFN和DFN子帧号：
DFN＝Floor(0.1×(Tcurrent-Tref-offsetDFN))mod1024
DFN子帧号＝Floor(Tcurrent-Tref-offsetDFN)mod 10
其中，Tcurrent为定时信息中包括的当前UTC时间(该值以毫秒表示)，Tref为UTC参考时间，offsetDFN为偏移值，该偏移值以毫秒表示，取值区间为0ms～1ms。
应当理解的是，终端设备可基于上述计算出的DFN和DFN子帧号，确定出当前无线帧周期的时域范围，并在时域上与GNSS保持同步。也就是说，终端设备可将上述计算出的DFN和DFN子帧号作为对后续子帧循环计数的起始子帧位置。进一步地，终端设备可将起始子帧位置之后的预留子帧确定为目标子帧。也就是说，目标子帧为当前无线帧周期和当前无线帧周期之后的各无线帧周期中包括的预留子帧。
举例来说，假设基于从GNSS接收的GNSS信号所确定出的DFN为20，DFN子帧号为3，则可将DFN＝20，DFN子帧号＝3作为对后续子帧循环计数的起始子帧位置。也就是说，在时域上，当前无线帧周期中包括的各个子帧是按照DFN＝20，DFN子帧号＝4，DFN＝20，DFN子帧号＝5，……，DFN＝1023，DFN子帧号＝9进行计数的。当前无线帧周期之后的各无线帧周期是按照DFN＝0，DFN子帧号＝0，DFN＝0，DFN子帧号＝1，……，DFN＝1023，DFN子帧号＝8，DFN＝1023，DFN子帧号＝9的规律进行循环计数的。因此，终端设备可将该起始子帧位置之后的预留子帧确定为目标子帧。也就是说，当前无线帧周期中包括的目标子帧的DFN f 0和DFN子帧号s 0满足
Figure PCTCN2020106444-appb-000026
s 0＝i 0-f 0×10，i 0＝256×m，其中，m为整数且1≤m≤39。即当前无线帧周期中共包括39个目标子帧，其分别为当前无线帧周期中的第256个子帧(即DFN为25，DFN子帧号为6的子帧)，第512个子帧(即DFN为51，DFN子帧号为2的子帧)，……，第9984个子帧(即DFN为998，DFN子帧号为4的子帧)。当前无线帧周期之后的各无线帧周期中包括的目标子帧的DFN f 0和DFN子帧 号s 0满足
Figure PCTCN2020106444-appb-000027
s 0＝i 0-f 0×10，i 0＝256×m，其中，m为整数且0≤m≤39。
具体地，当终端设备进入自同步状态时，如果终端设备能够读取到事先存储的DFN和DFN子帧号，即可将该DFN和DFN子帧号作为对后续子帧循环计数的起始子帧位置，进而将起始子帧位置之后，属于第一类预配置子帧的子帧或者第二类预配置子帧的子帧确定为目标子帧。应当理解的是，上述事先存储的DFN和DFN子帧号可以为终端设备最近一次以GNSS作为参考同步源时，所确定出的DFN和DFN子帧号。其中，终端设备与参考同步源每进行一次同步，即可更新存储DFN和DFN子帧号为当前一次同步过程所确定出的DFN和DFN子帧号。
可选的，当终端设备为一个新设备时，或者，当终端设备处于关机重启后的初始状态时，或者，当终端设备自开机后，从未以GNSS作为过参考同步源时，终端设备中存储的DFN和DNF子帧号为空。此时，终端设备不能读取到DFN和DFN子帧号。因此，终端设备可随机确定一个DFN和DFN子帧号作为对后续子帧循环计数的起始子帧位置，进而将起始子帧位置之后的第一类预配置子帧或者第二类预配置子帧确定为目标子帧。
举例来说，假设预配置子帧为子帧配置位图中比特位序号k＝0对应的子帧，且每个无线帧周期中第1个子帧～第100个子帧中包括的一个预配置子帧为第二类预配置子帧。又假设终端设备读取到的事先存储的DFN和DFN子帧号分别为DFN＝25，DFN子帧号＝6。因此，终端设备可将DFN＝25，DFN子帧号＝6作为对后续子帧循环计数的起始子帧位置。也就是说，在时域上，当前无线帧周期中包括的各个子帧是按照DFN＝25，DFN子帧号＝7，DFN＝25，DFN子帧号＝8，……，DFN＝1023，DFN子帧号＝9进行计数的。当前无线帧周期之后的各无线帧周期是按照DFN＝0，DFN子帧号＝0，DFN＝0，DFN子帧号＝1，……，DFN＝1023，DFN子帧号＝8，DFN＝1023，DFN子帧号＝9的规律进行循环计数。因此，终端设备可将该起始子帧位置之后的第一类预配置子帧或第二类预配置子帧确定为目标子帧。也就是说，终端设备可将起始子帧位置之后的属于第一类预配置子帧的子帧或者第二类预配置子帧的子帧确定为目标子帧。
例如，假设目标子帧为起始子帧位置之后的第一类预配置子帧，则当前无线帧周期中包括的目标子帧的DFN f 1和DFN子帧号s 1满足
Figure PCTCN2020106444-appb-000028
s 1＝i 1-f 1×10，
Figure PCTCN2020106444-appb-000029
其中，n 1为奇数且3≤n 1≤101，k＝0。也就是说，当前无线帧周期中共包括50个目标子帧，其分别为当前无线帧周期中的第302个子帧(即DFN为30，DFN子帧号为2的子帧)，第502个子帧(即DFN为50，DFN子帧号为2的子帧)，第703个子帧(即DFN为70，DFN子帧号为3的子帧)，……，第10140个子帧(即DFN为1014，DFN子帧号为0的子帧)。当前无线帧周期之后的各个无线帧周期中包括的目标子帧的DFN f 1和DFN子帧号s 1满足
Figure PCTCN2020106444-appb-000030
s 1＝i 1-f 1×10，
Figure PCTCN2020106444-appb-000031
其中，n 1为奇数且0≤n 1≤101，k＝0。
又例如，假设目标子帧为起始子帧位置之后的第二类预配置子帧，则当前无线帧周期中包括的目标子帧的DFNf 2和DFN子帧号s 2满足
Figure PCTCN2020106444-appb-000032
s 2＝i 2-f 2×10，
Figure PCTCN2020106444-appb-000033
其中，n 2为偶数且4≤n 2≤101，k＝0。也就是说，当前无线帧周期中共包括49个目标子帧，其分别为当前无线帧周期中的第402个子帧(即DFN为40，DFN子帧号为2的子帧)，第603个子帧(即DFN为60，DFN子帧号为3的子帧)，第804个子帧(即DFN为80，DFN子帧号为4的子帧)，……，第10010个子帧(即DFN为1001，DFN子帧号为0的子帧)。当前无线帧周期之后的各个无线帧周期中包括的目标子帧的DFN和DFN子帧号满足
Figure PCTCN2020106444-appb-000034
s 2＝i 2-f 2×10，
Figure PCTCN2020106444-appb-000035
其中，n 2为偶数且0≤n 2≤101，k＝0。
S102、终端设备在目标子帧中发送直通链路同步信号。
在一些可行的实施方式中，当终端设备确定出目标子帧后，可直接在目标子帧上发送直通链路同步信号。应当理解的是，上述直通链路同步信号符合3GPP制定的车联网标准。具体地，该直通链路同步信号中包括直通链路主同步信号(primary sidelink synchronization signal，PSSS)，直通链路辅同步信号(secondary sidelink synchronization signal，SSSS)，物理直通链路广播信道(physical sidelink broadcast channel，PSBCH)和解调参考信号(demodulation reference signals，DMRS)。其中，PSSS和SSSS的格式和内容可参见3GPP36.211标准中的9.7章节和3GPP 36.331标准中的5.10.7.3章节，PSBCH的格式和内容可参见3GPP36.211标准中的9.6章节与3GPP 36.331标准中的5.10.7.4章节，DMRS的格式和内容可参见3GPP36.211标准中的9.8章节和5.5.2.1章节。
可选的，在一些可行的实施方式中，为提高直通链路同步信号的发送可控性，当确定出目标子帧后，终端设备还可以通过获取信号发送控制参数，根据该信号发送控制参数进一步确定是否在该目标子帧中发送直通链路同步信号。
通常而言，信号发送控制参数可在终端设备出厂时，进行预先设置。例如，信号发送控制参数可事先烧录或存储在终端设备中。因此，当终端设备读取到信号发送控制参数时，若信号发送控制参数指示确定出的目标子帧用于发送直通链路同步信号，则终端设备可在目标子帧中发送直通链路同步信号。
具体地，当终端设备的参考同步源为空且确定出目标子帧为无线帧周期中包括的第一类预配置子帧或第二类预配置子帧时，获取信号发送控制参数，若信号发送控制参数指示无线帧周期中包括的预配置子帧用于发送直通链路同步信号，则在目标子帧中发送直通链路同步信号。当终端设备的参考同步源为GNSS且确定出目标子帧为无线帧周期中包括的预留子帧时，获取信号发送控制参数，若信号发送控制参数指示无线帧周期中包括的预留子帧用于发送直通链路同步信号，则在目标子帧中发送直通链路同步信号。
可选的，在一些可行的实施方式中，当终端设备的参考同步源为GNSS时，若确定目标子帧为无线帧周期中包括的预留子帧，且获取的信号发送控制参数指示无线帧周期中的 预留子帧不用于发送直通链路同步信号时，则终端设备可从无线帧周期包括的预配置子帧中重新确定出目标子帧，并在重新确定出的目标子帧上发送直通链路同步信号。也就是说，当信号发送控制参数指示预留子帧不用于发送直通链路同步信号时，终端设备可将第一类预配置子帧或第二类预配置子帧确定为目标子帧，并在重新确定出的目标子帧上发送直通链路同步信号。可选的，当终端设备重新确定目标子帧为第一类预配置子帧或第二类预配置子帧时，还可以进一步根据信号发送控制参数确定目标子帧是否被指示用于发送直通链路同步信号。其中，当信号发送控制参数指示预配置子帧用于发送直通链路同步信号时，则终端设备执行在重新确定出的目标子帧上发送直通链路同步信号。
应当理解的是，不同取值的信号发送控制参数的具体含义可进行事先约定。例如，可事先约定信号发送控制参数包括u个比特。其中，一个比特用于指示一种子帧类型的子帧是否用于发送直通链路同步信号。举例来说，假设信号发送控制参数包括2个比特，其中，一个比特用于指示预留子帧是否用于发送直通链路同步信号，另一个比特用于指示预配置子帧是否用于发送直通链路同步信号。因此，可事先约定当比特位上的比特值为1时，指示对应子帧类型的子帧用于发送直通链路同步信号，当比特位上的比特值为0时，指示对应子帧类型的子帧不用于发送直通链路同步信号。或者，也可以事先约定当比特位上的比特值为0时，指示对应子帧类型的子帧用于发送直通链路同步信号，当比特位上的比特值为1时，指示对应子帧类型的子帧不用于发送直通链路同步信号，具体可根据实际应用场景确定，在此不做限制。
可选的，在一些可行的实施方式中，当终端设备确定出目标子帧后，还可以通过对目标子帧的子帧占用情况进行监听，以确定目标子帧是否用于发送直通链路同步信号。其中，当确定目标子帧中没有发送其他类型的数据或信号时，终端设备可执行在目标子帧中发送直通链路同步信号。
可选的，在一些可行的实施方式中，当且仅当信号发送控制参数指示目标子帧用于发送直通链路同步信号，且通过监听确定目标子帧中没有发送其他类型的数据或信号时，终端设备在目标子帧中发送直通链路同步信号。
在本申请实施例中，终端设备通过从无线帧周期包括的预留子帧或预配置子帧中确定出目标子帧，可在目标子帧中发送直通链路同步信号。采用本申请实施例，可解决基于LTE-V2X的中国行业标准，终端设备无法通过PC5接口发送直通链路同步信号以建立与其他终端设备之间同步的问题。也就是说，本申请实施例增加了终端设备之间同步方式的多样性。其中，一方面，针对终端设备在无法接收到符合信号质量要求的GNSS信号的场景下，终端设备之间无法建立同步的问题，本申请实施例通过从预配置子帧中确定目标子帧，并在目标子帧中发送直通链路同步信号，可解决该场景下V2X系统因为无法建立同步而无法正常工作的问题。另一方面，针对各终端设备能够接收到符合信号质量要求的GNSS信号，并且可基于GNSS信号建立终端设备之间的同步的场景下，本申请实施例进一步扩展了终端设备与其他终端设备建立同步的方式，即通过在预留子帧中发送直通链路同步信号以建立终端设备之间的同步。
实施例二
当任一终端设备(为方便描述，以第二终端设备为例进行说明)基于上述实施一中提供的方法，在CCSA制定的LTE-V2X中国行业标准下，能够发送符合3GPP制定的车联网标准的直通链路同步信号(为方便描述，以第一直通链路同步信号为例进行说明)时，则接收到该第一直通链路同步信号的终端设备(为方便描述，以第一终端设备为例进行说明)可基于第一直通链路同步信号与第二终端设备在时域上保持同步。与此同时，第一终端设备还可以通过发送直通链路同步信号(为方便描述，以第二直通链路同步信号为例进行说明)与其他终端设备(例如第三终端设备)建立同步。应当理解的是，本申请实施例中所涉及的直通链路同步信号(例如，第一直通链路同步信号和第二直通链路同步信号)皆符合3GPP制定的车联网标准。本申请实施例中包括的各终端设备(例如，第一终端设备、第二终端设备和第三终端设备)皆为支持CCSA制定的车联网标准的终端设备。
请参见图4，图4是本申请实施例提供的直通链路同步信号的发送方法的另一流程示意图。
S201、第一终端设备从第二终端设备接收第一直通链路同步信号。
在一些可行的实施方式中，第一终端设备可通过搜索同步信号来确定参考同步源。具体地，当第一终端设备没有搜索到GNSS信号时，或搜索到的GNSS信号不满足信号质量要求时，如果第一终端设备还可以搜索到满足信号质量要求的第一直通链路同步信号，则第一终端设备可将发送该第一直通链路同步信号的第二终端设备确定为参考同步源。
不难理解的是，为提高搜索效率或监听效率，第一终端设备可以256ms为信号监听周期在时域上监听直通链路同步信号以接收直通链路同步信号。也就是说，第一终端设备可通过依次扫描256ms中每个子帧中是否存在同步信号，来确定该段时间内是否有同步源发送了同步信号。可选的，信号监听周期还可以设置为大于256ms的其他时长，例如，512ms等，具体根据实际应用场景确定，在此不做限制。
具体地，第一终端设备通过从第二终端设备接收第一直通链路同步信号，可得到该第一直通链路同步信号中携带的DFN(为方便描述，以第一DFN为例进行说明)和DFN子帧号(为方便描述，以第一DFN子帧号为例进行说明)。其中，第一DFN和第一DFN子帧号用于指示第一子帧。其中，第一子帧可理解为第一终端设备接收到第一直通链路同步信号时的子帧。或者，第一子帧可理解为第二终端设备发送该第一直通链路同步信号时占用的子帧。
S202、第一终端设备基于第一子帧从无线帧周期包括的预配置子帧中确定出目标子帧。
在一些可行的实施方式中，当第一终端设备得到第一DFN和第一DFN子帧号后，可根据第一DFN和第一DFN子帧号确定出当前无线帧周期的时域范围，并在时域上与第二终端设备保持同步。也就是说，第一终端设备可将第一DFN和第一DFN子帧号作为对后续子帧(即第一子帧之后的子帧)循环计数的起始子帧位置。进一步地，根据第一子帧可从起始子帧位置之后的预配置子帧中确定出目标子帧。
具体地，当第一子帧为无线帧周期包括的预留子帧中的一个时，第一终端设备可确定目标子帧为无线帧周期中包括的预配置子帧，即第一终端设备可将起始子帧位置之后的第一类预配置子帧或者第二类预配置子帧确定为目标子帧。当第一子帧为无线帧周期中包括的第一类预配置子帧中的一个时，第一终端设备可确定目标子帧为无线帧周期中包括的第 二类预配置子帧，即第一终端设备可将起始子帧位置之后的第二类预配置子帧确定为目标子帧。当第一子帧为无线帧周期中包括的第二类预配置子帧中的一个时，第一终端设备可确定目标子帧为无线帧周期中包括的第一类预配置子帧，即第一终端设备可将起始子帧位置之后的第一类预配置子帧确定为目标子帧。
举例来说，假设预配置子帧为子帧配置位图中比特位序号k＝0对应的子帧，且每个无线帧周期中第1个子帧～第100个子帧中包括的一个预配置子帧为第二类预配置子帧。又假设第一直通链路同步信号中携带的第一DFN为25，第一DFN子帧号为6，即第一子帧的DFN＝25，DFN子帧号＝6。因此，可将DFN＝25，DFN子帧号＝6作为对后续子帧循环计数的起始子帧位置。也就是说，在时域上，当前无线帧周期中包括的各个子帧是按照DFN＝25，DFN子帧号＝7，DFN＝25，DFN子帧号＝8，……，DFN＝1023，DFN子帧号＝9的规律进行计数的。当前无线帧周期之后的各无线帧周期是按照DFN＝0，DFN子帧号＝0，DFN＝0，DFN子帧号＝1，……，DFN＝1023，DFN子帧号＝8，DFN＝1023，DFN子帧号＝9的规律进行循环计数的。其中，由于第一DFN＝25，第一DFN子帧号＝6所指示的子帧为预留子帧，因此，可将该起始子帧位置之后的第一类预配置子帧或第二类预配置子帧确定为目标子帧。也就是说，目标子帧为第一子帧之后，且属于第一类预配置子帧的子帧或者第二子帧的子帧。
又举例来说，假设预配置子帧为子帧配置位图中比特位序号k＝0对应的子帧，且每个无线帧周期中第1个子帧～第100个子帧中包括的一个预配置子帧为第二类预配置子帧。又假设第一直通链路同步信号中携带的第一DFN为10，第一DFN子帧号为1，即第一子帧的DFN＝10，DFN子帧号＝1。因此，可将DFN＝10，DFN子帧号＝1作为对第一子帧之后的子帧循环计数的起始子帧位置。也就是说，在时域上，当前无线帧周期中包括的各个子帧是按照DFN＝10，DFN子帧号＝2，DFN＝10，DFN子帧号＝3，……，DFN＝1023，DFN子帧号＝9进行计数的。当前无线帧周期之后的各无线帧周期是按照DFN＝0，DFN子帧号＝0，DFN＝0，DFN子帧号＝1，……，DFN＝1023，DFN子帧号＝8，DFN＝1023，DFN子帧号＝9的规律进行循环计数。其中，由于DFN＝10，DFN子帧号＝1所指示的子帧为第一类预配置子帧，因此，可将该起始子帧位置之后的第二类预配置子帧确定为目标子帧。也就是说，目标子帧为第一子帧之后，且属于第二类预配置子帧的子帧。
S203、第一终端设备在目标子帧中发送第二直通链路同步信号。
在一些可行的实施方式中，当第一终端设备确定出目标子帧后，可直接在目标子帧上发送第二直通链路同步信号。
可选的，在一些可行的实施方式中，为提高发送直通链路同步信号的可控性，当确定出目标子帧后，第一终端设备还可以通过获取信号发送控制参数，根据该信号发送控制参数进一步确定是否在该目标子帧中发送直通链路同步信号。
具体地，当目标子帧为无线帧周期中包括的第一类预配置子帧或第二类预配置子帧时，获取信号发送控制参数，若信号发送控制参数指示无线帧周期中包括的预配置子帧用于发送直通链路同步信号，则执行在目标子帧中发送第二直通链路同步信号的步骤。
通常而言，信号发送控制参数可在终端设备出厂时，进行预先设置。例如，信号发送控制参数可事先烧录或存储在终端设备中。应当理解的是，不同取值的信号发送控制参数 的具体含义可进行事先约定。例如，可事先约定信号发送控制参数包括u个比特。其中，一个比特用于指示一种子帧类型的子帧是否用于发送直通链路同步信号。举例来说，假设信号发送控制参数包括2个比特，其中，一个比特用于指示预留子帧是否用于发送直通链路同步信号，另一个比特用于指示预配置子帧是否用于发送直通链路同步信号。因此，可事先约定当比特位上的比特值为1时，指示对应子帧类型的子帧用于发送直通链路同步信号，当比特位上的比特值为0时，指示对应子帧类型的子帧不用于发送直通链路同步信号。或者，也可以事先约定当比特位上的比特值为0时，指示对应子帧类型的子帧用于发送直通链路同步信号，当比特位上的比特值为1时，指示对应子帧类型的子帧不用于发送直通链路同步信号，具体可根据实际应用场景确定，在此不做限制。
可选的，在一些可行的实施方式中，当第一终端设备确定出目标子帧后，在发送直通链路同步信号之前，还可以对目标子帧的子帧占用情况进行监听，以确定目标子帧是否已经被占用。应当理解的是，当确定目标子帧没有被占用，即目标子帧中没有发送其他数据或信号时，第一终端设备可在目标子帧中发送第二直通链路同步信号。
可选的，在一些可行的实施方式中，当确定出目标子帧后，还可以根据第一直通链路同步信号的信号质量，确定是否发送直通链路同步信号。通常而言，当第一终端设备从参考同步源(即第二终端设备)接收的直通链路同步信号比较弱时，第一终端设备可通过发送直通链路同步信号与其他终端设备建立同步。例如，当第一直通链路同步信号的信号质量小于预设的同步信号质量门限时，第一终端设备可在目标子帧中发送第二直通链路同步信号。
可选的，在一些可行的实施方式中，当基于信号发送控制参数和/或通过监听的方式和/或基于信号质量确定目标子帧用于发送直通链路同步信号时，第一终端设备可执行在目标子帧中发送第二直通链路同步信号。
在本申请实施例中，第一终端设备通过从第二终端设备接收第一直通链路同步信号(即当第一终端设备的参考同步源为第二终端设备时)，可得到第一直通链路同步信号中携带第一DFN和第一DFN子帧号，其中，第一DFN和第一DFN子帧号用于指示第一子帧。进一步地，第一终端设备基于第一子帧可从无线帧周期包括的预配置子帧中确定出目标子帧，进而在目标子帧中发送第二直通链路同步信号。采用本申请实施例，可解决基于LTE-V2X的中国行业标准，终端设备以另一终端设备作为参考同步源时，无法发送直通链路同步信号的问题。也就是说，本申请实施例可实现针对工作在CCSA制定的车联网标准下的第一终端设备，当其参考同步源为工作在相同车联网标准(即CCSA制定的车联网标准)的第二终端设备时，该第一终端设备通过发送直通链路同步信号建立与其他终端设备之间同步的方案。
请参见图5，图5是本申请实施例提供的一种直通链路同步信号的发送装置一结构示意图。该装置可为前文实施例一或实施例二中叙述的终端设备，该装置可用于执行上述实施例一或实施例二中描述的终端设备的功能。为了便于说明，图5中仅示出了该装置的主要部件。由图5可知，该装置包括处理器、存储器、射频电路、天线以及输入/输出装置。处理器主要用于对通信协议以及通信数据进行处理，以及对装置进行控制，执行软件程序，处理软件程序的数据等。存储器主要用于存储软件程序和数据。射频电路主要用于基带信 号与射频信号的转换以及对射频信号的处理。天线主要用于收发电磁波形式的射频信号。输入输出装置，例如触摸屏、显示屏，键盘等主要用于接收使用该装置的用户输入的数据以及对该用户输出数据。需要说明的是，在某些场景下，该通信设备可以不包括输入输出装置。
当需要发送数据时，处理器对待发送的数据进行基带处理后，输出基带信号至射频电路，射频电路将基带信号进行射频处理后将射频信号通过天线以电磁波的形式向外发送。当有数据发送到终端设备时，射频电路通过天线接收到射频信号，将射频信号转换为基带信号，并将基带信号输出至处理器，处理器将基带信号转换为数据并对该数据进行处理。为便于说明，图5中仅示出了一个存储器和处理器。在实际的装置产品中，可以存在一个或多个处理器和一个或多个存储器。存储器也可以称为存储介质或者存储设备等。存储器可以是独立于处理器设置，也可以是与处理器集成在一起，本申请实施例对此不做限制。
作为一种可选的实现方式，处理器可以包括基带处理器和/或中央处理器，基带处理器主要用于对通信协议以及通信数据进行处理，中央处理器主要用于对整个终端设备进行控制，执行软件程序，处理软件程序的数据。图5中的处理器可以集成基带处理器和中央处理器的功能，本领域技术人员可以理解，基带处理器和中央处理器也可以是各自独立的处理器，通过总线等技术互联。本领域技术人员可以理解，终端设备可以包括多个基带处理器以适应不同的网络制式，终端设备可以包括多个中央处理器以增强其处理能力，终端设备的各个部件可以通过各种总线连接。上述基带处理器也可以表述为基带处理电路或者基带处理芯片。上述中央处理器也可以表述为中央处理电路或者中央处理芯片。对通信协议以及通信数据进行处理的功能可以内置在处理器中，也可以以软件程序的形式存储在存储单元中，由处理器执行软件程序以实现基带处理功能。
在本申请实施例中，可以将具有收发功能的天线和射频电路视为装置的收发单元，将具有处理功能的处理器视为装置的处理单元。如图5所示，该装置包括收发单元310和处理单元320。这里，收发单元也可以称为收发器、收发机、收发装置等。处理单元320也可以称为处理器，处理单板，处理模块、处理装置等。可选的，可以将收发单元310中用于实现接收功能的器件视为接收单元，将收发单元310中用于实现发送功能的器件视为发送单元，即收发单元310包括接收单元和发送单元。这里，接收单元有时也可以称为接收机、接收器、或接收电路等。发送单元有时也可以称为发射机、发射器或者发射电路等。
应理解，收发单元310用于执行上述实施例一或实施二描述的检测并接收GNSS信号或直通链路同步信号的过程以及发送直通链路同步信号的步骤。处理单元320用于执行实施一或实施例二中从无线帧周期中确定目标子帧等步骤。
请参见图6，图6是本申请实施例提供的一种直通链路同步信号的发送装置又一结构示意图。该装置可以为上述实施例一或者实施例二中的终端设备，该装置可用于实现终端设备所实现的通信方法。该装置包括：处理器41、存储器42、收发器43。
存储器42包括但不限于是RAM、ROM、EPROM或CD-ROM，该存储器42用于存储相关指令及数据。存储器42存储了如下的元素，可执行模块或者数据结构，或者它们的子集，或者它们的扩展集：
操作指令：包括各种操作指令，用于实现各种操作。
操作系统：包括各种系统程序，用于实现各种基础业务以及处理基于硬件的任务。
图6中仅示出了一个存储器，当然，存储器也可以根据需要，设置为多个。
收发器43可以是通信模块、收发电路。应用在本申请实施例中，收发器43用于执行上述实施例中所涉及的接收GNSS信号或直通链路同步信号、以及发送直通链路同步信号等操作。
处理器41可以是控制器，CPU，通用处理器，DSP，ASIC，FPGA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申请实施例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41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等。
具体的应用中，装置的各个组件可通过总线系统耦合在一起，该线系统除包括数据总线之外，还可以包括电源总线、控制总线和状态信号总线等。
本申请实施例还提供了一种计算机可读介质，其上存储有计算机程序，该计算机程序被计算机执行时实现上述实施例中终端设备执行的方法或者步骤。
本申请实施例还提供了一种计算机程序产品，该计算机程序产品被计算机执行时实现上述实施例中终端设备执行的方法或者步骤。
本申请实施例还提供了一种装置，该装置可以是上述实施例中的终端设备。该装置包括处理器和接口。该处理器用于执行上述实施例中终端设备执行的方法或者步骤。应理解，上述终端设备可以是一个芯片，上述处理器可以通过硬件来实现也可以通过软件来实现，当通过硬件实现时，该处理器可以是逻辑电路、集成电路等。当通过软件来实现时，该处理器可以是一个通用处理器，通过读取存储器中存储的软件代码来实现，该存储器可以集成在处理器中，可以位于上述处理器之外，独立存在。
应注意，实际应用中，本申请实施例中的处理器可以是一种集成电路芯片，具有信号的处理能力。在实现过程中，上述方法实施例的各步骤可以通过处理器中的硬件的集成逻辑电路或者软件形式的指令完成。上述的处理器可以是通用处理器、数字信号处理器(digital signal Processor，DSP)、专用集成电路(application specific integrated circuit，ASIC)、现成可编程门阵列(field programmable gate array，FPGA)或者其他可编程逻辑器件、分立门或者晶体管逻辑器件、分立硬件组件。可以实现或者执行本申请实施例中的公开的各方法、步骤及逻辑框图。
需要说明的是，本申请还提供一种通信系统，其包括前述的一个或多个终端设备。
在上述方法实施例中，可以全部或部分地通过软件、硬件、固件或者其任意组合来实现。当使用软件实现时，可以全部或部分地以计算机程序产品的形式实现。上述计算机程序产品包括一个或多个计算机指令。在计算机上加载和执行上述计算机指令时，全部或部分地产生按照本申请实施例上述的流程或功能。上述计算机可以是通用计算机、专用计算机、计算机网络、或者其他可编程装置。上述计算机指令可以存储在计算机可读存储介质中，或者从一个计算机可读存储介质向另一个计算机可读存储介质传输，例如，上述计算机指令可以从一个网站站点、计算机、服务器或数据中心通过有线(例如同轴电缆、光纤、数字用户线(digital subscriber Line，DSL)或无线(例如红外、无线、微波等)方式向另一个网站站点、计算机、服务器或数据中心进行传输。上述计算机可读存储介质可以是计 算机能够存取的任何可用介质或者是包含一个或多个可用介质集成的服务器、数据中心等数据存储设备。上述可用介质可以是磁性介质(例如，软盘、硬盘、磁带)、光介质(例如，高密度数字视频光盘(digital video disc，DVD)、或者半导体介质(例如，固态硬盘(solid state disk，SSD)等。
应注意，实际应用中，本申请实施例中的处理器可以是一种集成电路芯片，具有信号的处理能力。在实现过程中，上述方法实施例的各步骤可以通过处理器中的硬件的集成逻辑电路或者软件形式的指令完成。上述的处理器可以是通用处理器、数字信号处理器(digital signal Processor，DSP)、专用集成电路(application specific integrated circuit，ASIC)、现成可编程门阵列(field programmable gate array，FPGA)或者其他可编程逻辑器件、分立门或者晶体管逻辑器件、分立硬件组件。可以实现或者执行本申请实施例中的公开的各方法、步骤及逻辑框图。通用处理器可以是微处理器或者该处理器也可以是任何常规的处理器等。结合本申请实施例所公开的方法的步骤可以直接体现为硬件译码处理器执行完成，或者用译码处理器中的硬件及软件模块组合执行完成。软件模块可以位于随机存储器，闪存、只读存储器，可编程只读存储器或者电可擦写可编程存储器、寄存器等本领域成熟的存储介质中。该存储介质位于存储器，处理器读取存储器中的信息，结合其硬件完成上述方法的步骤。
可以理解，本申请实施例中的存储器可以是易失性存储器或非易失性存储器，或可包括易失性和非易失性存储器两者。其中，非易失性存储器可以是只读存储器(read-only memory，ROM)、可编程只读存储器(programmable ROM，PROM)、可擦除可编程只读存储器(erasable PROM，EPROM)、电可擦除可编程只读存储器(electrically EPROM，EEPROM)或闪存。易失性存储器可以是随机存取存储器(random access memory，RAM)，其用作外部高速缓存。通过示例性但不是限制性说明，许多形式的RAM可用，例如静态随机存取存储器(static RAM，SRAM)、动态随机存取存储器(dynamic RAM，DRAM)、同步动态随机存取存储器(synchronous DRAM，SDRAM)、双倍数据速率同步动态随机存取存储器(double data rate SDRAM，DDR SDRAM)、增强型同步动态随机存取存储器(enhanced SDRAM，ESDRAM)、同步连接动态随机存取存储器(synchlink DRAM，SLDRAM)和直接内存总线随机存取存储器(direct rambus RAM，DR RAM)。应注意，本申请实施例描述的存储器旨在包括但不限于这些和任意其它适合类型的存储器。

Claims (36)

  1. 一种直通链路同步信号的发送方法，其特征在于，所述方法包括：
    终端设备从无线帧周期包括的预留子帧或预配置子帧中确定出目标子帧，所述无线帧周期包括10240个子帧，所述10240个子帧中包括40个预留子帧，所述预配置子帧为所述无线帧周期中由子帧配置位图中比特值为0的一个比特位所指示的子帧；
    所述终端设备在所述目标子帧中发送直通链路同步信号，所述直通链路同步信号包括直通链路主同步信号PSSS、直通链路辅同步信号SSSS、物理直通链路广播信道PSBCH和解调参考信号DMRS。
  2. 根据权利要求1所述的发送方法，其特征在于，所述无线帧周期中的预留子帧的直接帧号DFN f和DFN子帧号s满足：
    Figure PCTCN2020106444-appb-100001
    其中，m为整数且0≤m≤39。
  3. 根据权利要求1所述的发送方法，其特征在于，所述无线帧周期中除40个预留子帧之外的10200个子帧中每连续的100个子帧由一个子帧配置位图指示，所述子帧配置位图包括100个比特位，一个比特位指示一个子帧，其中，每连续的100个子帧中包括由所述子帧配置位图中比特值为0的一个比特位所指示的一个预配置子帧。
  4. 根据权利要求1或3所述的发送方法，其特征在于，当所述终端设备获取不到全球导航卫星系统GNSS信号时，所述目标子帧为所述无线帧周期包括的预配置子帧，且所述目标子帧的DFN f和DFN子帧号s满足：
    Figure PCTCN2020106444-appb-100002
    n为小于102的奇数；
    其中，k为子帧配置位图中比特值为0的一个比特位对应的比特位序号。
  5. 根据权利要求1或3所述的发送方法，其特征在于，当所述终端设备获取不到GNSS信号时，所述目标子帧为所述无线帧周期包括的预配置子帧，且所述目标子帧的DFN f和DFN子帧号s满足：
    Figure PCTCN2020106444-appb-100003
    n为小于102的偶数；
    其中，k为子帧配置位图中比特值为0的一个比特位对应的比特位序号。
  6. 根据权利要求1或2所述的发送方法，其特征在于，当所述终端设备获取到GNSS信号时，所述目标子帧为所述无线帧周期中包括的预留子帧。
  7. 根据权利要求4或5所述的发送方法，其特征在于，所述终端设备在所述目标子帧中发送直通链路同步信号之前，所述方法还包括：
    所述终端设备获取信号发送控制参数，若所述信号发送控制参数指示无线帧周期中包括的预配置子帧用于发送直通链路同步信号，则执行在所述目标子帧中发送直通链路同步信号的步骤。
  8. 根据权利要求6所述的发送方法，其特征在于，所述终端设备在所述目标子帧中发 送直通链路同步信号之前，所述方法还包括：
    所述终端设备获取信号发送控制参数，若所述信号发送控制参数指示无线帧周期中包括的预留子帧用于发送直通链路同步信号，则执行在所述目标子帧中发送直通链路同步信号的步骤。
  9. 根据权利要求8所述的发送方法，其特征在于，若所述信号发送控制参数指示所述无线帧周期中的预留子帧不用于发送直通链路同步信号时，所述方法还包括：
    所述终端设备从所述无线帧周期包括的预配置子帧中重新确定出目标子帧，并在重新确定出的目标子帧上发送直通链路同步信号；
    其中，重新确定出的目标子帧的DFN f和DFN子帧号s满足：
    Figure PCTCN2020106444-appb-100004
    n为小于102的奇数；
    其中，k为子帧配置位图中比特值为0的一个比特位对应的比特位序号。
  10. 根据权利要求8所述的发送方法，其特征在于，若所述信号发送控制参数指示所述无线帧周期中的预留子帧不用于发送直通链路同步信号时，所述方法还包括：
    所述终端设备从所述无线帧周期包括的预配置子帧中重新确定出目标子帧，并在重新确定出的目标子帧上发送直通链路同步信号；
    其中，重新确定出的目标子帧的DFN f和DFN子帧号s满足：
    Figure PCTCN2020106444-appb-100005
    n为小于102的偶数；
    其中，k为子帧配置位图中比特值为0的一个比特位对应的比特位序号。
  11. 一种直通链路同步信号的发送方法，其特征在于，所述直通链路同步信号包括直通链路主同步信号PSSS、直通链路辅同步信号SSSS、物理直通链路广播信道PSBCH和解调参考信号DMRS，所述方法包括：
    第一终端设备从第二终端设备接收第一直通链路同步信号，所述第一直通链路同步信号中携带第一直接帧号DFN和第一DFN子帧号，所述第一DFN和所述第一DFN子帧号用于指示第一子帧；
    所述第一终端设备基于所述第一子帧从无线帧周期包括的预配置子帧中确定出目标子帧，所述无线帧周期包括10240个子帧，所述10240个子帧中包括40个预留子帧，所述预配置子帧为所述无线帧周期中由子帧配置位图中比特值为0的一个比特位所指示的子帧；
    所述第一终端设备在所述目标子帧中发送第二直通链路同步信号。
  12. 根据权利要求11所述的发送方法，其特征在于，所述第一终端设备从第二终端设备接收第一直通链路同步信号之前，所述方法还包括：
    所述第一终端设备以256ms为信号监听周期在时域上监听直通链路同步信号以接收直通链路同步信号。
  13. 根据权利要求11或12所述的发送方法，其特征在于，所述无线帧周期中的预留子帧的DFN f和DFN子帧号s满足：
    Figure PCTCN2020106444-appb-100006
    其中，m为整数且0≤m≤39。
  14. 根据权利要求11所述的发送方法，其特征在于，所述无线帧周期中除40个预留子帧之外的10200个子帧中每连续的100个子帧由一个子帧配置位图指示，所述子帧配置位图包括100个比特位，一个比特位指示一个子帧，其中，每连续的100个子帧中包括由所述子帧配置位图中比特值为0的一个比特位所指示的一个预配置子帧。
  15. 根据权利要求11或14所述的发送方法，其特征在于，所述无线帧周期包括的预配置子帧中包括第一类预配置子帧和第二类预配置子帧；
    所述第一类预配置子帧的DFN f和DFN子帧号s满足：
    Figure PCTCN2020106444-appb-100007
    n为奇数且0≤n≤101；
    所述第二类预配置子帧的DFN f和DFN子帧号s满足：
    Figure PCTCN2020106444-appb-100008
    n为偶数且0≤n≤101；
    其中，k为子帧配置位图中比特值为0的一个比特位对应的比特位序号；
    当所述第一子帧为所述无线帧周期包括的第一类预配置子帧时，所述目标子帧为所述无线帧周期包括的第二类预配置子帧；
    当所述第一子帧为所述无线帧周期包括的第二类预配置子帧时，所述目标子帧为所述无线帧周期包括的第一类预配置子帧。
  16. 根据权利要求15所述的发送方法，其特征在于，当所述第一子帧为所述无线帧周期包括的预留子帧时，所述目标子帧为所述无线帧周期中的所述第一类预配置子帧。
  17. 根据权利要求15所述的发送方法，其特征在于，当所述第一子帧为所述无线帧周期包括的预留子帧时，所述目标子帧为所述无线帧周期中的所述第二类预配置子帧。
  18. 根据权利要求11-17任一项所述的发送方法，其特征在于，所述第一终端设备在所述目标子帧中发送第二直通链路同步信号之前，所述方法还包括：
    所述第一终端设备获取信号发送控制参数，若所述信号发送控制参数指示无线帧周期中包括的预配置子帧用于发送直通链路同步信号，则执行在所述目标子帧中发送第二直通链路同步信号的步骤。
  19. 一种直通链路同步信号的发送装置，其特征在于，所述发送装置包括：
    处理单元，用于从无线帧周期包括的预留子帧或预配置子帧中确定出目标子帧，所述无线帧周期包括10240个子帧，所述10240个子帧中包括40个预留子帧，所述预配置子帧为所述无线帧周期中由子帧配置位图中比特值为0的一个比特位所指示的子帧；
    收发单元，用于在所述目标子帧中发送直通链路同步信号，所述直通链路同步信号包括直通链路主同步信号PSSS、直通链路辅同步信号SSSS、物理直通链路广播信道PSBCH和解调参考信号DMRS。
  20. 根据权利要求19所述的发送装置，其特征在于，所述无线帧周期中的预留子帧的直接帧号DFN f和DFN子帧号s满足：
    Figure PCTCN2020106444-appb-100009
    其中，m为整数且0≤m≤39。
  21. 根据权利要求19所述的发送装置，其特征在于，所述无线帧周期中除40个预留子帧之外的10200个子帧中每连续的100个子帧由一个子帧配置位图指示，所述子帧配置位图包括100个比特位，一个比特位指示一个子帧，其中，每连续的100个子帧中包括由所述子帧配置位图中比特值为0的一个比特位所指示的一个预配置子帧。
  22. 根据权利要求19或21所述的发送装置，其特征在于，当获取不到全球导航卫星系统GNSS信号时，所述目标子帧为所述无线帧周期包括的预配置子帧，且所述目标子帧的DFN f和DFN子帧号s满足：
    Figure PCTCN2020106444-appb-100010
    n为小于102的奇数；
    其中，k为子帧配置位图中比特值为0的一个比特位对应的比特位序号。
  23. 根据权利要求19或21所述的发送装置，其特征在于，当获取不到GNSS信号时，所述目标子帧为所述无线帧周期包括的预配置子帧，且所述目标子帧的DFN f和DFN子帧号s满足：
    Figure PCTCN2020106444-appb-100011
    n为小于102的偶数；
    其中，k为子帧配置位图中比特值为0的一个比特位对应的比特位序号。
  24. 根据权利要求19或20所述的发送装置，其特征在于，当获取到GNSS信号时，所述目标子帧为所述无线帧周期中包括的预留子帧。
  25. 根据权利要求22或23所述的发送装置，其特征在于，
    所述处理单元用于：获取信号发送控制参数；
    所述收发单元，用于若所述信号发送控制参数指示无线帧周期中包括的预配置子帧用于发送直通链路同步信号，则执行在所述目标子帧中发送直通链路同步信号的步骤。
  26. 根据权利要求24所述的发送装置，其特征在于，
    所述处理单元用于：获取信号发送控制参数；
    所述收发单元用于：若所述信号发送控制参数指示无线帧周期中包括的预留子帧用于发送直通链路同步信号，则执行在所述目标子帧中发送直通链路同步信号的步骤。
  27. 根据权利要求26所述的发送装置，其特征在于，
    所述处理单元用于：若确定所述信号发送控制参数指示所述无线帧周期中的预留子帧不用于发送直通链路同步信号，则从所述无线帧周期包括的预配置子帧中重新确定出目标子帧；
    所述收发单元用于：在重新确定出的目标子帧上发送直通链路同步信号；
    其中，重新确定出的目标子帧的DFN f和DFN子帧号s满足：
    Figure PCTCN2020106444-appb-100012
    n为小于102的奇数；
    其中，k为子帧配置位图中比特值为0的一个比特位对应的比特位序号。
  28. 根据权利要求26所述的发送装置，其特征在于，
    所述处理单元用于：若确定所述信号发送控制参数指示所述无线帧周期中的预留子帧 不用于发送直通链路同步信号，则从所述无线帧周期包括的预配置子帧中重新确定出目标子帧；
    所述收发单元用于：在重新确定出的目标子帧上发送直通链路同步信号；
    其中，重新确定出的目标子帧的DFN f和DFN子帧号s满足：
    Figure PCTCN2020106444-appb-100013
    n为小于102的偶数；
    其中，k为子帧配置位图中比特值为0的一个比特位对应的比特位序号。
  29. 一种直通链路同步信号的发送装置，其特征在于，所述直通链路同步信号包括直通链路主同步信号PSSS、直通链路辅同步信号SSSS、物理直通链路广播信道PSBCH和解调参考信号DMRS，所述发送装置包括：
    收发单元，用于从第二终端设备接收第一直通链路同步信号，所述第一直通链路同步信号中携带第一直接帧号DFN和第一DFN子帧号，所述第一DFN和所述第一DFN子帧号用于指示第一子帧；
    处理单元，用于基于所述第一子帧从无线帧周期包括的预配置子帧中确定出目标子帧，所述无线帧周期包括10240个子帧，所述10240个子帧中包括40个预留子帧，所述预配置子帧为所述无线帧周期中由子帧配置位图中比特值为0的一个比特位所指示的子帧；
    所述收发单元，用于在所述目标子帧中发送第二直通链路同步信号。
  30. 根据权利要求29所述的发送装置，其特征在于，所述收发单元还用于：
    以256ms为信号监听周期在时域上监听直通链路同步信号以接收直通链路同步信号。
  31. 根据权利要求29或30所述的发送装置，其特征在于，所述无线帧周期中的预留子帧的DFN f和DFN子帧号s满足：
    Figure PCTCN2020106444-appb-100014
    其中，m为整数且0≤m≤39。
  32. 根据权利要求29所述的发送装置，其特征在于，所述无线帧周期中除40个预留子帧之外的10200个子帧中每连续的100个子帧由一个子帧配置位图指示，所述子帧配置位图包括100个比特位，一个比特位指示一个子帧，其中，每连续的100个子帧中包括由所述子帧配置位图中比特值为0的一个比特位所指示的一个预配置子帧。
  33. 根据权利要求29或32所述的发送装置，其特征在于，所述无线帧周期包括的预配置子帧中包括第一类预配置子帧和第二类预配置子帧；
    所述第一类预配置子帧的DFN f和DFN子帧号s满足：
    Figure PCTCN2020106444-appb-100015
    n为奇数且0≤n≤101；
    所述第二类预配置子帧的DFN f和DFN子帧号s满足：
    Figure PCTCN2020106444-appb-100016
    n为偶数且0≤n≤101；
    其中，k为子帧配置位图中比特值为0的一个比特位对应的比特位序号；
    当所述第一子帧为所述无线帧周期包括的第一类预配置子帧时，所述目标子帧为所述 无线帧周期包括的第二类预配置子帧；
    当所述第一子帧为所述无线帧周期包括的第二类预配置子帧时，所述目标子帧为所述无线帧周期包括的第一类预配置子帧。
  34. 根据权利要求33所述的发送装置，其特征在于，当所述第一子帧为所述无线帧周期包括的预留子帧时，所述目标子帧为所述无线帧周期中的所述第一类预配置子帧。
  35. 根据权利要求33所述的发送装置，其特征在于，当所述第一子帧为所述无线帧周期包括的预留子帧时，所述目标子帧为所述无线帧周期中的所述第二类预配置子帧。
  36. 根据权利要求29-35任一项所述的发送装置，其特征在于，
    所述处理单元用于：获取信号发送控制参数；
    所述收发单元用于：若所述信号发送控制参数指示无线帧周期中包括的预配置子帧用于发送直通链路同步信号，则执行在所述目标子帧中发送第二直通链路同步信号的步骤。
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