WO2021208751A1 - 一种时间同步方法及装置 - Google Patents

一种时间同步方法及装置 Download PDF

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Publication number
WO2021208751A1
WO2021208751A1 PCT/CN2021/085071 CN2021085071W WO2021208751A1 WO 2021208751 A1 WO2021208751 A1 WO 2021208751A1 CN 2021085071 W CN2021085071 W CN 2021085071W WO 2021208751 A1 WO2021208751 A1 WO 2021208751A1
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WIPO (PCT)
Prior art keywords
information
time
terminal device
reference time
value
Prior art date
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PCT/CN2021/085071
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English (en)
French (fr)
Inventor
徐小英
屈凯旸
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华为技术有限公司
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Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Priority to EP21788434.5A priority Critical patent/EP4132133A4/en
Publication of WO2021208751A1 publication Critical patent/WO2021208751A1/zh
Priority to US17/966,087 priority patent/US20230036797A1/en

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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
    • H04W56/00—Synchronisation arrangements
    • H04W56/004—Synchronisation arrangements compensating for timing error of reception due to propagation delay
    • H04W56/0045—Synchronisation arrangements compensating for timing error of reception due to propagation delay compensating for timing error by altering transmission time
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W56/00—Synchronisation arrangements
    • H04W56/004—Synchronisation arrangements compensating for timing error of reception due to propagation delay
    • H04W56/005—Synchronisation arrangements compensating for timing error of reception due to propagation delay compensating for timing error by adjustment in the receiver
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W56/00—Synchronisation arrangements
    • H04W56/001—Synchronization between nodes
    • H04W56/0015—Synchronization between nodes one node acting as a reference for the others
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W56/00—Synchronisation arrangements
    • H04W56/0055—Synchronisation arrangements determining timing error of reception due to propagation delay
    • H04W56/0065—Synchronisation arrangements determining timing error of reception due to propagation delay using measurement of signal travel time
    • H04W56/009—Closed loop measurements
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Definitions

  • This application relates to the field of communication technology, and in particular to a time synchronization method and device.
  • a wireless access network device may include a network-side separate nodes, such as a centralized unit (central unit, CU) unit and distributed (distributed unit, DU) .
  • a network-side separate nodes such as a centralized unit (central unit, CU) unit and distributed (distributed unit, DU) .
  • This application provides a time synchronization method and device to reduce the complexity of time synchronization for terminal equipment.
  • an embodiment of the present application provides a time synchronization method, which may be applicable to a first communication device, and the first communication device is a CU or a chip in the CU.
  • the first communication device is a CU or a chip in the CU.
  • the CU determines the first reference time, the first reference time is the reference time of the terminal device at the reference point; and the first information is sent to the terminal device, and the first information is used for Indicates the first reference time.
  • the terminal device can obtain the reference time of the terminal device at the reference point from the CU.
  • the terminal device is based on the DU-side reference time obtained from the CU and the order between the terminal device and the DU.
  • the transmission delay is used to determine the reference time of the terminal device at the reference point, the processing complexity of the terminal device can be effectively reduced, and the power consumption of the terminal device can be saved.
  • determining the first reference time by the CU may mean that the CU receives the second information and the third information from the DU; where the second information is used to indicate the second reference time, and the second reference time is The reference time of the DU at the reference point, and the third information is used to determine the one-way transmission delay between the DU and the terminal device; and the CU is based on the second reference time and the one-way transmission time Delay to determine the first reference time.
  • the CU receiving the third information from the DU may mean: the CU sends the first request information to the DU, the first request information is used to request the one-way transmission delay, and the first request information includes The identifier of the terminal device; and receiving the third information sent by the DU.
  • the first request information is carried in a reference time information report control message, or a downlink RRC transmission message, or a context establishment request message of a terminal device, or a context modification request message of a terminal device.
  • the method further includes: the CU receives capability information from the DU, where the capability information is used to indicate that the DU supports reporting the one-way transmission delay.
  • the CU can send the first request information to the DU after determining that the DU supports reporting the one-way transmission delay according to the capability information of the DU.
  • the third information includes at least one of the following: (1) a first time length, the first time length characterizing the loopback transmission delay between the DU and the terminal device; the first time The length is obtained by measuring the first uplink signal or the second uplink signal sent by the terminal equipment; the first uplink signal is a random access preamble, and the second uplink signal is different from the first uplink signal; (2) the second time The second time length is half of the first time length; (3) the timing advance TA value of the terminal device; (4) half of the TA value; (5) the adjustment amount corresponding to the TA value.
  • the time accuracy of the first time length or the second time length is higher than the time accuracy of the TA value.
  • the reference time of the terminal device at the reference point determined by the CU can better meet the requirements of high-precision time synchronization.
  • the time accuracy of the first time length or the second time length is nanoseconds or ten nanoseconds.
  • the method when the third information includes the adjustment amount corresponding to the TA value, the method further includes: if the adjustment amount corresponding to the TA value is the first adjustment amount, then the CU according to the first adjustment amount Determine the TA value, and then determine the one-way transmission delay according to the TA value; or, if the adjustment amount corresponding to the TA value is the second adjustment amount, the CU determines according to the original TA value and the second adjustment amount The TA value, and in turn, the TA value determine the one-way transmission delay.
  • the number of bits included in the cell used to carry the first adjustment amount is greater than 12; or, the number of bits included in the cell used to carry the second adjustment amount is greater than 6.
  • the time accuracy of the adjustment amount of the TA value can be effectively improved, so that the reference time of the terminal device at the reference point determined by the CU can better meet the requirements of high-precision time synchronization.
  • the third information further includes the identification of the terminal device.
  • determining the first reference time by the CU may mean that the CU receives fourth information from the DU, and the fourth information is used to indicate the first reference time.
  • the CU receives the fourth information from the DU, which may mean: the CU sends the second request information to the DU.
  • the second request information is used to request the first reference time, and the second request information includes the terminal device information. Identification; and, receiving the fourth information sent by the DU.
  • the CU receiving the fourth information from the DU may mean that the CU sends a reference time information report control message to the DU, where the reference time information report control message includes the identification of the terminal device; and, Receive the fourth information sent by the DU.
  • the reference time information report control message further includes indication information, and the indication information is used to indicate that the reference time requested by the reference time information report control message is the reference time of the terminal device at the reference point.
  • the first information includes multiple time parameters corresponding to the first reference time.
  • the first information further includes at least one of the following: (1) reference point information, used to indicate the reference point; (2) time type information, used to indicate the time type of the first reference time ; (3) Uncertain error value.
  • the first information is carried in an RRC message.
  • the CU can send the first information to the terminal device through high-level signaling (such as an RRC message), the security of information transmission can be effectively guaranteed.
  • the embodiments of the present application provide a time synchronization method, which can be applied to a second communication device, and the second communication device is a DU or a chip in the DU.
  • the DU determines the second information and the third information, and sends the second information and the third information to the CU; where the second information is used to indicate the second reference time, and the second information is used to indicate the second reference time.
  • the second reference time is the reference time of the DU at the reference point
  • the third information is used to determine the one-way transmission delay between the DU and the terminal device.
  • the DU sending the third information to the CU may mean that the DU receives the first request information from the CU, the first request information is used to request the one-way transmission delay, and the first request information includes The identifier of the terminal device; and the DU sends third information to the CU according to the first request information.
  • the first request information is carried in a reference time information report control message, or a downlink RRC transmission message, or a context establishment request message of a terminal device, or a context modification request message of a terminal device.
  • the method further includes: the DU sends capability information of the DU to the CU, where the capability information is used to indicate that the DU supports reporting the one-way transmission delay.
  • the DU sending the second information and the third information to the CU may mean that the DU receives the first request information from the CU.
  • the first request information is used to request the second information and the third information.
  • the request information includes the identification of the terminal device; and, after the DU determines that it supports reporting the one-way transmission delay, it sends the second information and the third information to the CU.
  • the third information includes at least one of the following: (1) a first time length, the first time length characterizing the loopback transmission delay between the DU and the terminal device; the first time The length is obtained by measuring the first uplink signal or the second uplink signal sent by the terminal equipment; the first uplink signal is a random access preamble, and the second uplink signal is different from the first uplink signal; (2) the second time The second time length is half of the first time length; (3) the TA value of the terminal device; (4) half of the TA value; (5) the adjustment amount corresponding to the TA value.
  • the time accuracy of the first time length or the second time length is higher than the time accuracy of the TA value.
  • the time accuracy of the first time length or the second time length is nanoseconds or ten nanoseconds.
  • the adjustment amount corresponding to the TA value is the first adjustment amount or the second adjustment amount; wherein the number of bits included in the cell used to carry the first adjustment amount is greater than 12; or, use The number of bits included in the cell carrying the second adjustment amount is greater than 6.
  • the third information further includes the identification of the terminal device.
  • an embodiment of the present application provides a time synchronization method, which can be applied to a second communication device, and the second communication device is a DU or a chip in the DU. Take this method for DU as an example.
  • the DU determines the first reference time and sends fourth information to the CU.
  • the fourth information is used to indicate the first reference time.
  • the first reference time is the terminal device at the reference point. Reference time.
  • the DU sends the fourth information to the CU, including: receiving the second request information from the CU, the second request information is used to request the first reference time, and the second request information includes the identification of the terminal device; The second request message sends the fourth message to the CU.
  • the DU sends the fourth information to the CU, including: receiving a reference time information report control message from the CU, the reference time information report control message includes the identification of the terminal device; and the reference time information report control message is sent to the CU according to the reference time information report control message. Send the fourth message.
  • the reference time information report control message further includes indication information, and the indication information is used to indicate that the reference time requested by the reference time information report control message is the reference time of the terminal device at the reference point.
  • determining the first reference time by the DU includes: determining the second reference time by the DU, where the second reference time is the reference time of the DU at the reference point; and determining the DU and the One-way transmission delay between terminal devices; further, the DU determines the first reference time according to the second reference time and the one-way transmission delay.
  • the one-way transmission delay determined by the DU may mean that the DU obtains the first time length by measuring the first uplink signal or the second uplink signal sent by the terminal equipment, and the first uplink signal is random Access to the preamble, the second uplink signal is different from the first uplink signal; the first time length characterizes the loopback transmission delay between the DU and the terminal device; and the one-way transmission delay is determined according to the first time length; Alternatively, the DU determines the TA value of the terminal device, and determines the one-way transmission delay according to the TA value.
  • the time accuracy of the first time length is higher than the time accuracy of the TA value.
  • the time accuracy of the first time length is nanoseconds or ten nanoseconds.
  • an embodiment of the present application provides a time synchronization method, which can be applied to a third communication device, and the third communication device is a terminal device or a chip in the terminal device.
  • the terminal equipment receives first information, the first information is used to indicate a first reference time, and the first reference time is the reference time of the terminal equipment at the reference point; further, according to Time synchronization is performed at the first reference time.
  • the terminal device may receive the first information from the CU or DU.
  • time synchronization methods described in the second, third, and fourth aspects described above correspond to the time synchronization methods described in the first aspect, and the beneficial effects of related technical features can be referred to the description of the first aspect.
  • the present application provides a communication device.
  • the communication device may be a CU or a chip set inside the CU.
  • the communication device has the function to implement the first aspect described above.
  • the communication device includes a module or unit or means corresponding to the steps involved in the first aspect described above, and the function or unit or means can be implemented by software , Or it can be realized by hardware, or it can be realized by hardware executing corresponding software.
  • the communication device includes a processing unit and a communication unit.
  • the communication unit can be used to send and receive signals to achieve communication between the communication device and other devices.
  • the communication unit is used to receive Configuration information of the network device; the processing unit can be used to perform some internal operations of the communication device.
  • the functions performed by the processing unit and the communication unit may correspond to the steps involved in the first aspect described above.
  • the communication device includes a processor, and may also include a transceiver.
  • the transceiver is used to send and receive signals.
  • the processor executes program instructions to complete any possible design or design in the first aspect.
  • the communication device may further include one or more memories, and the memories are used for coupling with the processor.
  • the one or more memories may be integrated with the processor, or may be provided separately from the processor, which is not limited in this application.
  • the memory may store necessary computer programs or instructions to realize the functions involved in the first aspect described above.
  • the processor can execute the computer program or instruction stored in the memory, and when the computer program or instruction is executed, the communication device realizes the method in any possible design or implementation manner of the first aspect.
  • the communication device includes a processor and a memory, and the memory can store necessary computer programs or instructions for realizing the functions involved in the first aspect.
  • the processor can execute the computer program or instruction stored in the memory, and when the computer program or instruction is executed, the communication device realizes the method in any possible design or implementation manner of the first aspect.
  • the communication device includes at least one processor and an interface circuit, where at least one processor is used to communicate with other devices through the interface circuit and execute any possible design or implementation of the first aspect described above.
  • the method in the way.
  • the present application provides a communication device.
  • the communication device may be a DU or a chip set inside the DU.
  • the communication device is capable of implementing the functions related to the second aspect or the third aspect.
  • the communication device includes modules or units or means corresponding to the steps related to the second aspect or the third aspect, and the functions or units Or means can be realized by software, or by hardware, or by hardware executing corresponding software.
  • the communication device includes a processing unit and a communication unit.
  • the communication unit can be used to send and receive signals to achieve communication between the communication device and other devices.
  • the communication unit is used to communicate with the terminal.
  • the device sends system information; the processing unit can be used to perform some internal operations of the communication device.
  • the functions performed by the processing unit and the communication unit may correspond to the steps involved in the second or third aspect described above.
  • the communication device includes a processor, and may also include a transceiver.
  • the transceiver is used to send and receive signals, and the processor executes program instructions to complete any of the above-mentioned second or third aspects.
  • the communication device may further include one or more memories, and the memories are used for coupling with the processor.
  • the one or more memories may be integrated with the processor, or may be provided separately from the processor, which is not limited in this application.
  • the memory may store necessary computer programs or instructions for realizing the functions related to the second aspect or the third aspect.
  • the processor can execute the computer program or instruction stored in the memory, and when the computer program or instruction is executed, the communication device realizes any of the possible designs or implementations of the second aspect or the third aspect. method.
  • the communication device includes a processor and a memory, and the memory can store necessary computer programs or instructions for realizing the functions related to the second aspect or the third aspect.
  • the processor can execute the computer program or instruction stored in the memory, and when the computer program or instruction is executed, the communication device realizes any of the possible designs or implementations of the second aspect or the third aspect. method.
  • the communication device includes at least one processor and an interface circuit, where at least one processor is used to communicate with other devices through the interface circuit, and perform any of the above-mentioned second or third aspects.
  • the present application provides a communication system, which may include the communication device described in the fifth aspect and the communication device described in the sixth aspect.
  • the communication system may also include terminal equipment.
  • the present application provides a computer-readable storage medium, which stores computer-readable instructions.
  • the computer reads and executes the computer-readable instructions, the computer executes the first aspects to Any possible design method of the fourth aspect.
  • this application provides a computer program product, which when a computer reads and executes the computer program product, causes the computer to execute any of the possible design methods of the first to fourth aspects.
  • the present application provides a chip including a processor coupled to a memory, and configured to read and execute a software program stored in the memory, so as to implement the first to fourth aspects described above. Any one of the possible design methods.
  • FIG. 1 is a schematic diagram of a network architecture to which an embodiment of this application is applicable;
  • 2a is a schematic diagram of downlink data transmission between various layers provided by an embodiment of this application.
  • 2b is a schematic diagram of a CU-DU separation architecture provided by an embodiment of the application.
  • Figure 2c is a schematic diagram of another CU-DU separation architecture provided by an embodiment of the application.
  • 2d is a schematic diagram of another CU-DU separation architecture provided by an embodiment of this application.
  • FIG. 3 is a schematic diagram of a flow of high-precision time synchronization between a terminal device and a wireless network side according to an embodiment of the application;
  • FIG. 4 is a schematic diagram of uplink time adjustment provided by an embodiment of the application.
  • FIG. 5 is a schematic flowchart corresponding to the time synchronization method provided in Embodiment 1 of this application; FIG.
  • FIG. 6 is a schematic flowchart corresponding to the time synchronization method provided in the second embodiment of the application.
  • FIG. 7 is a schematic flowchart corresponding to the time synchronization method provided in the third embodiment of the application.
  • FIG. 8 is a possible exemplary block diagram of a device involved in an embodiment of this application.
  • FIG. 9 is a schematic structural diagram of a network device provided by an embodiment of this application.
  • FIG. 1 is a schematic diagram of a network architecture to which an embodiment of this application is applicable.
  • a terminal device such as a terminal device 1301 or a terminal device 1302
  • the wireless network includes radio access network (RAN) and core network (CN).
  • RAN is used to connect terminal equipment to the wireless network
  • CN is used to manage terminal equipment and provide Gateway for external network communication.
  • the terminal equipment, RAN, and CN involved in FIG. 1 are respectively described in detail below.
  • the terminal device includes a device that provides voice and/or data connectivity to the user, for example, it may include a handheld device with a wireless connection function, or a processing device connected to a wireless modem.
  • the terminal device can communicate with the core network via a radio access network (RAN), and exchange voice and/or data with the RAN.
  • RAN radio access network
  • the terminal equipment may include user equipment (UE), wireless terminal equipment, mobile terminal equipment, device-to-device communication (device-to-device, D2D) terminal equipment, vehicle to everything (V2X) terminal equipment , Machine-to-machine/machine-type communications (M2M/MTC) terminal equipment, Internet of things (IoT) terminal equipment, subscriber unit, subscriber station (subscriber) station), mobile station (mobile station), remote station (remote station), access point (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.
  • UE user equipment
  • M2M/MTC Machine-to-machine/machine-type communications
  • IoT Internet of things
  • subscriber unit subscriber station (subscriber) station)
  • mobile station mobile station
  • remote station remote station
  • access point access point
  • AP remote terminal
  • remote terminal remote terminal
  • access terminal access terminal
  • user terminal user terminal
  • user Agent
  • it may include mobile phones (or “cellular” phones), computers with mobile terminal equipment, portable, pocket-sized, hand-held, mobile devices with built-in computers, and so on.
  • PCS personal communication service
  • PCS cordless phones
  • SIP session initiation protocol
  • WLL wireless local loop
  • PDA personal digital assistants
  • restricted devices such as devices with low power consumption, or devices with limited storage capabilities, or devices with limited computing capabilities. Examples include barcodes, radio frequency identification (RFID), sensors, global positioning system (GPS), laser scanners and other information sensing equipment.
  • RFID radio frequency identification
  • GPS global positioning system
  • laser scanners and other information sensing equipment.
  • the RAN may include one or more RAN devices, such as the RAN device 1101 and the RAN device 1102.
  • the interface between the RAN device and the terminal device may be a Uu interface (or called an air interface).
  • Uu interface or called an air interface.
  • the names of these interfaces may not change or may be replaced by other names, which is not limited in this application.
  • the RAN device is a node or device that connects terminal devices to the wireless network, and the RAN device can also be called a network device or a base station.
  • RAN equipment include but are not limited to: a new generation Node B (gNB) in a 5G communication system, an evolved node B (eNB), a radio network controller (RNC), and a node B (node B, NB), base station controller (BSC), base transceiver station (BTS), home base station (for example, home evolved nodeB, or home node B, HNB), baseband unit (baseBand) unit, BBU), transmission and receiving point (transmitting and receiving point, TRP), transmitting point (TP), mobile switching center, etc.
  • gNB new generation Node B
  • eNB evolved node B
  • RNC radio network controller
  • BSC base station controller
  • BTS base transceiver station
  • home base station for example, home evolved nodeB, or home node B, HNB
  • control plane protocol layer structure can include the RRC layer, the packet data convergence protocol (packet data convergence protocol, PDCP) layer, and radio link control (radio link control).
  • RRC layer packet data convergence protocol
  • PDCP packet data convergence protocol
  • radio link control radio link control
  • RLC layer media access control
  • MAC media access control
  • user plane protocol layer structure can include PDCP layer, RLC layer, MAC layer and physical layer and other protocol layer functions
  • the PDCP layer may also include a service data adaptation protocol (SDAP) layer.
  • SDAP service data adaptation protocol
  • FIG. 2a shows a schematic diagram of downlink data transmission between layers.
  • the downward arrow indicates data transmission
  • the upward arrow indicates data reception.
  • the PDCP layer After the PDCP layer obtains the data from the upper layer, it transmits the data to the RLC layer and the MAC layer, and then the MAC layer generates a transmission block, and then performs wireless transmission through the physical layer. Data is encapsulated correspondingly in each layer.
  • the data received by a certain layer from the upper layer of the layer is regarded as the service data unit (SDU) of the layer, and after layer encapsulation, it becomes a PDU, and then is passed to the lower layer.
  • SDU service data unit
  • the terminal device also has an application layer and a non-access layer; where the application layer can be used to provide services to applications installed in the terminal device, for example, the terminal device receives Downlink data can be sequentially transmitted from the physical layer to the application layer, and then provided to the application program by the application layer; for another example, the application layer can obtain data generated by the application program, and transmit the data to the physical layer in turn, and send it to other communication devices.
  • the non-access layer can be used to forward user data, such as forwarding uplink data received from the application layer to the SDAP layer or forwarding downlink data received from the SDAP layer to the application layer.
  • the RAN device may include a centralized unit (centralized unit, CU) and a distributed unit (distributed unit, DU), and multiple DUs may be centrally controlled by one CU.
  • a centralized unit centralized unit, CU
  • a distributed unit distributed unit
  • multiple DUs may be centrally controlled by one CU.
  • the interface between the CU and the DU may be referred to as an F1 interface, where the control panel (CP) interface may be F1-C, and the user panel (UP) interface may be F1-U.
  • CP control panel
  • UP user panel
  • CU and DU can be divided according to the protocol layers of the wireless network: For example, as shown in Figure 2b, the functions of the PDCP layer and above are set in the CU, and the functions of the protocol layers below the PDCP layer (such as the RLC layer and the MAC layer, etc.) are set in the DU; For another example, as shown in Figure 2c, the functions of the protocol layers above the PDCP layer are set in the CU, and the functions of the PDCP layer and below the protocol layers are set in the DU.
  • CU or DU can be divided into functions with more protocol layers, for example
  • the CU or DU can also be divided into part of the processing functions with the protocol layer.
  • part of the functions of the RLC layer and the functions of the protocol layer above the RLC layer are set in the CU, and the remaining functions of the RLC layer and the functions of the protocol layer below the RLC layer are set in the DU.
  • the functions of the CU or DU can also be divided according to service types or other system requirements, for example, by delay, and the functions that need to meet the delay requirements for processing time are set in the DU, and the delay does not need to be met.
  • the required function is set in the CU.
  • the CU may also have one or more functions of the core network.
  • the CU can be set on the network side to facilitate centralized management; the DU can have multiple radio frequency functions, or the radio frequency functions can be set remotely. The embodiment of the present application does not limit this.
  • the function of the CU may be implemented by one entity, or may also be implemented by different entities.
  • the functions of the CU can be further divided, that is, the control plane and the user plane are separated and implemented by different entities, which are the control plane CU entity (ie CU-CP entity) and the user plane CU entity. (Ie CU-UP entity).
  • the CU-CP entity and the CU-UP entity can be coupled with the DU to jointly complete the function of the RAN device.
  • the signaling generated by the CU may be sent to the terminal device through the DU, or the signaling generated by the terminal device may be sent to the CU through the DU.
  • the DU may directly pass the protocol layer encapsulation without analyzing the signaling and transparently transmit it to the terminal device or CU.
  • the sending or receiving of the signaling by the DU includes this scenario.
  • the RRC or PDCP layer signaling will eventually be processed as physical layer signaling and sent to the terminal device, or converted from received physical layer signaling.
  • the RRC or PDCP layer signaling can also be considered to be sent by the DU, or sent by the DU and radio frequency load.
  • the CN may include one or more CN devices, such as the CN device 120.
  • CN can include access and mobility management function (AMF) network elements, session management function (session management function, SMF) network elements, and user plane function (user plane function).
  • AMF access and mobility management function
  • SMF session management function
  • user plane function user plane function
  • UPF policy control function
  • UDM unified data management
  • AF application function
  • the number of devices in the communication system shown in FIG. 1 is only for illustration, and the embodiments of the present application are not limited to this. In actual applications, the communication system may also include more terminal devices and more RAN devices. Other devices can also be included.
  • the network architecture shown in Figure 1 above can be applied to various radio access technology (RAT) communication systems, such as 4G (or called long term evolution (LTE)) communication systems. It can also be a 5G (or new radio (NR)) communication system, or a transition system between an LTE communication system and a 5G communication system. The transition system can also be referred to as a 4.5G communication system. It can be in the future communication system.
  • RAT radio access technology
  • 4G or called long term evolution (LTE)
  • LTE long term evolution
  • NR new radio
  • the network architecture and business scenarios described in the embodiments of this application are intended to more clearly illustrate the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided in the embodiments of this application. Those of ordinary skill in the art will know that with communication With the evolution of the network architecture and the emergence of new business scenarios, the technical solutions provided in the embodiments of the present application are equally applicable to similar technical problems.
  • a possible implementation is: CU obtains the DU side from the DU Reference time and send the reference time on the DU side to the terminal device; accordingly, the terminal device can determine the reference time on the terminal device side according to the reference time on the DU side and the one-way transmission delay between the terminal device and the DU, and then Realize high-precision time synchronization between the terminal equipment and the wireless network side.
  • the process of high-precision time synchronization between the terminal device and the wireless network side will be described in detail below in conjunction with FIG. 3.
  • Fig. 3 is a schematic diagram of the process of high-precision time synchronization between the terminal device and the wireless network side. As shown in Fig. 3, the process may include:
  • Step 301 The CU sends a reference time information report control message to the DU, and the reference time information report control message is used to request a reference time on the DU side.
  • Step 302 The DU sends a reference time information report (reference time information report) message to the CU, where the reference time information report message is used to indicate the reference time on the DU side.
  • a reference time information report reference time information report
  • Step 303 The CU sends the reference time on the DU side to the terminal device.
  • Step 304 The terminal device receives a timing advance command (TAC) sent by the DU, and determines a timing advance (TA) value of the terminal device according to the timing advance command.
  • TAC timing advance command
  • TA timing advance
  • Step 305 The terminal device obtains the one-way transmission delay between the terminal device and the DU according to the TA value, and then determines the reference time on the terminal device side according to the reference time on the DU side and the one-way transmission delay between the terminal device and the DU .
  • Step 306 The terminal device performs high-precision time synchronization according to the reference time on the terminal device side.
  • the reference time on the DU side can be understood as the reference time of the DU at the reference point
  • the reference time on the terminal device side can be understood as the reference time of the terminal device at the reference point.
  • the reference point may be pre-defined by the protocol, or may also be indicated by the DU or CU, which is not specifically limited.
  • the reference point may be the start boundary or the end boundary of the radio frame corresponding to the reference system frame number (SFN).
  • SFN reference system frame number
  • the CU sends the reference time on the DU side to the terminal device.
  • the terminal device After the terminal device receives the reference time on the DU side, it needs to combine the one-way transmission delay between the terminal device and the DU to determine the terminal device Therefore, the processing complexity of the terminal device is relatively high.
  • the terminal device determines the one-way transmission delay between the terminal device and the DU based on the TA (for example, the one-way transmission delay is equal to one-half of the TA value). Because the accuracy of the TA value is low, it is possible As a result, the reference time of the terminal device determined by the terminal device cannot meet the requirements of high-precision time synchronization.
  • an embodiment of the present application will focus on the implementation of high-precision time synchronization between the terminal device and the wireless network in the scenario where the CU and the DU are separated.
  • an embodiment of the present application provides a time synchronization method, which is used to reduce the complexity of time synchronization performed by a terminal device.
  • time in the embodiments of the present application can also be understood as a clock.
  • the concepts of time and clock are not distinguished, that is, time and clock can be regarded as equivalent concepts.
  • the terminal device performs time synchronization, which can also be understood as the terminal device performs clock synchronization.
  • the terminal device can achieve downlink synchronization with the network device by receiving the synchronization signal and PBCH block (synchronization signal and PBCH block, SSB) sent by the network device, such as frame synchronization, so that the terminal device
  • PBCH block synchronization signal and PBCH block, SSB
  • the radio frame corresponding to the reference SFN can be learned according to the reference SFN, so that high-precision time synchronization can be performed at the start boundary or the end boundary of the radio frame corresponding to the reference SFN.
  • the SSB includes a primary synchronisation signal (PSS), a secondary synchronisation signal (SSS) and a physical broadcast channel ( physical broadcast channel , PBCH).
  • PSS primary synchronisation signal
  • SSS secondary synchronisation signal
  • PBCH physical broadcast channel
  • terminal device 1 and terminal device 2 as an example, as shown in Figure 4(a), due to the delay of signal propagation between the network device (such as DU) and the terminal device, from the start time of the network device sending the downlink signal to
  • c the speed of light.
  • ⁇ T 2 d 2 /c, where d 2 is the distance between the network device and the terminal device 2. If the terminal device 1 does not adjust the uplink timing, it sends an uplink signal to the network device based on the start time of receiving the downlink signal.
  • the interval from the start time of the terminal device 1 sending the uplink signal to the start time of the network device receiving the uplink signal The same is ⁇ T 1 . Therefore, for terminal device 1, the network device has a time difference of 2 ⁇ T 1 from the start time of sending the downlink signal to the start time of receiving the uplink signal. Similarly, for the terminal device 2, the network device is from the start time of sending the downlink signal to the start time of receiving the uplink signal. There is a time difference of 2 ⁇ T 2 at the beginning of receiving the uplink signal.
  • the interval (such as ⁇ T 1 or ⁇ T 2 ) from the start time when the network device sends the downlink signal to the start time when the terminal device receives the downlink signal is the downlink transmission time between the network device and the terminal device.
  • Delay the interval (for example, ⁇ T 1 or ⁇ T 2 ) from the start time when the terminal device sends the uplink signal to the start time when the network device receives the uplink signal is the uplink transmission delay between the network device and the terminal device.
  • the sum of the downlink transmission delay and the uplink transmission delay is the loopback transmission delay. It is assumed that the downlink transmission delay and the uplink transmission delay are equal. Therefore, the downlink transmission delay or the uplink transmission delay can also be referred to as the one-way transmission delay, and the loop-back transmission delay is equal to twice the one-way transmission delay.
  • the specific value of the loopback transmission delay will also be different. Therefore, there may be multiple time lengths that characterize the loopback transmission delay, such as the first time length and the TA value.
  • the network device can determine the first time length. For example, in the random access process, the network device can measure the start of the downlink signal sent by the network device in the same time slot according to the random access preamble sent by the terminal device. The interval from the start time to the start time of receiving the random access preamble of the same time slot is the first time length.
  • the network device can measure the starting time of the network device sending the downlink signal to the starting time of receiving the uplink signal according to the uplink signal sent by the terminal device
  • the interval is the third time length (because the terminal equipment has made timing adjustments when sending uplink signals, the third time length here can be understood as the adjustment amount of the first time length), and then the previous measurement is performed according to the third time length
  • the obtained first time length is updated to obtain a new first time length.
  • the time accuracy of the first time length may be one nanosecond or ten nanoseconds.
  • the updated first time length the first time length obtained from the last measurement— The third length of time.
  • the uplink signal in the non-random access process may be a sounding reference signal (sounding reference signal, SRS), or a demodulation reference signal (demodulation reference signal, DMRS), or a channel quality indicator (channel quality indicator, CQI), or Confirmation answer (acknowledgement, ACK), or negative answer (negative acknowledgement, NACK), or physical uplink shared channel (PUSCH).
  • SRS sounding reference signal
  • DMRS demodulation reference signal
  • CQI channel quality indicator
  • Confirmation answer acknowledgement
  • ACK negative answer
  • NACK physical uplink shared channel
  • the terminal device 1 advances the start time of sending the uplink signal by 2 ⁇ T 1
  • the terminal device 2 advances the start time of sending the uplink signal by 2 ⁇ T 2
  • the network device will receive the signal at the same time
  • the uplink signals of the terminal equipment 1 and the terminal equipment 2 thereby solving the problem of mutual interference between the terminal equipment.
  • the network device can determine the TA value and send a timing advance command to the terminal device, and the terminal device can determine the TA value according to the timing advance command; wherein the network device and the terminal device can both maintain the TA value.
  • the network device can determine the timing advance command according to the random access preamble sent by the terminal device, and send it to the terminal device through a random access response (RAR) Timing advance command; accordingly, the terminal device can obtain the TA value according to the timing advance command.
  • the timing advance command may include 12 bits (the corresponding value range is 0-3846).
  • the timing advance command may indicate the adjustment amount of the TA value (for ease of description, referred to as the first adjustment amount), and the terminal device may calculate the TA value according to the first adjustment amount.
  • the terminal device can determine the TA value with the following formula:
  • SCS subcarrier spacing
  • step 520.83ns.
  • N TA,offset may be equal to zero.
  • the network device may send a timing advance command to the terminal device in the connected state.
  • the timing advance may become invalid due to various reasons. Therefore, the terminal device needs to continuously update the timing advance.
  • the timing advance failure For example, for high-speed mobile terminal equipment (such as terminal equipment on a high-speed rail in operation), the transmission delay between it and the network equipment will continue to change, and it needs to be constantly changing. Update the timing advance.
  • the network device determines the timing advance command according to the uplink signal sent by the terminal device, and sends the timing advance command to the terminal device through a MAC control element (CE).
  • the timing advance command can include 6 bits (the corresponding value range is 0 to 63), the timing advance command can indicate the adjustment amount of the TA value (for ease of description, called the second adjustment amount), and the terminal device can be based on the second adjustment amount. Adjust the amount to calculate the TA value.
  • the terminal device can determine the TA value (also referred to as TAnew) by the following formula:
  • TAnew is the current uplink timing advance of the terminal device
  • TAold is the previous uplink timing advance of the terminal device.
  • Both the first time length and the TA value can represent the loopback transmission delay between the terminal device and the network device; wherein, from the perspective of the network device, the TA value can be obtained according to the first time length.
  • the network device can measure the first time length according to the random access preamble sent by the terminal device, and then determine the TA value (or timing advance command) according to the first time length.
  • the time accuracy of the first time length measured by the network equipment according to the random access preamble sent by the terminal equipment can be one nanosecond or ten nanoseconds, that is, the first time length determined by the network equipment is a value with higher time accuracy, but Since the timing advance command includes 12 bits (the step length of TA value adjustment is larger), the TA value of the terminal device is a value with a smaller time accuracy (time accuracy less than the first time length).
  • N TA, offset 0 as an example, if the network device measures the first time length as 1100 ns according to the random access preamble sent by the terminal device, then N can be determined according to the first time length.
  • the network device measures the first time length adjustment amount according to the uplink signal sent by the terminal device (because in the non-random access process, the terminal device is based on the uplink signal sent by TAold.
  • the network device can obtain the adjustment amount of the first time length according to the uplink signal measurement)
  • it can update the first time length according to the adjustment amount of the first time length to obtain the new first time length, and according to the new first time length
  • the length of time determines TAnew, and then determines the timing advance command (N TA2 ) according to TAnew and TAold.
  • the network device may also directly determine the timing advance command (N TA2 ) according to the adjustment amount of the first time length, and further, the network device may also determine TAnew according to N TA2 and TAold.
  • the above content is described by taking the interaction between the terminal device and the network device as an example, and it is also applicable to the scenario where the CU and the DU are separated.
  • the DU may determine the first time length and/or the TA value according to the above-described manner.
  • the value of the time accuracy may include two parts, the first part is a numerical value, and the second part is a time unit.
  • the second part of the time accuracy of the TA value depends on the smallest time unit of the TA value (such as ns), and the first part depends on the granularity (or step size) of the TA value adjustment (such as 520.83).
  • the time accuracy of the TA value is 520.83 ns.
  • the second part of the time accuracy of the first time length depends on the minimum time unit of the first time length, and the first part depends on the granularity of the first time length adjustment. Exemplarily, the smaller the value of the time accuracy, the higher the time accuracy; the larger the value, the lower the time accuracy.
  • the time synchronization method provided in the embodiment of the present application may include: the CU determines the first reference time, the first reference time is the reference time of the terminal device at the reference point, and the CU sends the first information to the terminal device. Used to indicate the first reference time; after receiving the first information, the terminal device can obtain the reference time of the terminal device at the reference point. In this way, the terminal device can obtain the reference time of the terminal device at the reference point from the CU, compared to the terminal device according to the DU side reference time obtained from the CU and the one-way transmission delay between the terminal device and the DU.
  • the solution of the reference time of the terminal device at the reference point can effectively reduce the processing complexity of the terminal device and save the power consumption of the terminal device.
  • the CU can send the first information to the terminal device through high-level signaling (such as an RRC message), the security of information transmission can be effectively guaranteed.
  • the above-mentioned method may include two possible schemes, namely scheme one and scheme two.
  • the CU can receive the second information and the third information from the DU; where the second information is used to indicate the second reference time, the second reference time is the reference time of the DU at the reference point, and the third information is used for Determine the one-way transmission delay between the DU and the terminal device; and, the CU may determine the first reference time according to the second reference time and the one-way transmission delay, and send the first information to the terminal device, where the first information is used to indicate The first reference time. In this way, the CU determines the first reference time according to the second information and the third information sent by the DU and sends it to the terminal device.
  • the CU Compared with the terminal device according to the DU side reference time obtained from the CU and the communication between the terminal device and the DU, it can ensure that the determined first reference time is more accurate.
  • the DU may determine the first reference time according to the second reference time and the one-way transmission delay, and send the first reference time to the CU, and then the CU sends the first information to the terminal device, and the first information is used to indicate The first reference time.
  • the DU determines the first reference time and sends it to the CU, and then the CU sends it to the terminal device.
  • the DU calculates the first reference time and sends it to the CU, and then the CU sends it to the terminal device.
  • the DU calculates the first reference time. Reference time, thereby reducing the signaling overhead between CU and DU.
  • the time synchronization method provided in the embodiment of the present application may include (for ease of description, referred to as solution three): the DU may determine the first reference time according to the second reference time and the one-way transmission delay, and combine the first reference time A reference time is sent to the terminal device. In this way, the DU determines the first reference time and sends it to the terminal device, thereby effectively improving the transmission efficiency and reducing the signaling overhead between the CU and the DU.
  • the reference time of the terminal device at the reference point can also be replaced with the reference time on the terminal device side; the reference time on the terminal device side refers to the time after the air interface transmission delay compensation.
  • the reference time of the DU at the reference point can also be replaced with: the reference time of the DU side, or the reference time of the network side at the reference point, or the reference time of the network side.
  • FIG. 5 is a schematic flowchart of the time synchronization method provided in Embodiment 1 of this application. As shown in Figure 5, it includes:
  • step 501 the CU sends the first request information to the DU, and accordingly, the DU receives the first request information.
  • the terminal device may send a time synchronization request to the CU; accordingly, after receiving the time synchronization request sent by the terminal device, the CU may send the first request information to the DU.
  • the CU may send the first request information to the DU.
  • Step 502 The DU sends second information and third information to the CU according to the first request information; the second information is used to indicate the second reference time, the second reference time is the reference time of the DU at the reference point, and the third information is used To determine the one-way transmission delay between the DU and the terminal equipment. Accordingly, the CU receives the second information and the third information.
  • the DU may send the second information and the third information to the CU through the same message.
  • the DU may send the second information and the third information to the CU through any of the following messages: reference time information report message, Initial uplink RRC transmission (initial uplink RRC message transfer) message, uplink RRC transmission (uplink RRC message transfer) message, terminal device context setup response (UE context setup response) message, terminal device context modification response (UE context modify response) information.
  • the DU may send the second information and the third information to the CU through different messages.
  • the DU may send the second information to the CU through a reference time information report message, and the DU may send the second information to the CU through an uplink RRC transmission message.
  • the terminal device sends the third information.
  • the first request information, the second information, the third information, etc. involved in the foregoing are respectively described in detail below.
  • the first request information may be carried in a reference time information report control message, or a downlink RRC transmission (downlink RRC message transfer) message, or a terminal device context setup request (UE context setup request) message, or a terminal device context modification request (UE context modify request) message.
  • the first request information can be used to request the second information and the third information, or in other words, the first request information can be used to request the second reference time and the one-way transmission delay.
  • the first request information may include information instructing the DU to report the second information and the third information (in other words, the information instructing the DU to report the second reference time and the one-way transmission delay).
  • the first request information may also include The identification of the terminal device.
  • the information instructing the DU to report the second information and the third information may include information instructing the DU to report the second information (for ease of description, referred to as information 1) and information instructing the DU to report the third information (referred to as information 2) ,
  • Information 1 and Information 2 may be the same information (for example, information carried in the same cell), or different information (for example, information carried in different cells).
  • the first request information may include the identification of the terminal device. In this case, the identification of the terminal device may be used to implicitly instruct the DU to report the second information and the third information.
  • the DU may send the second request information to the CU if it determines that the reference time information report control message includes the first request information.
  • Information and third information for example, the DU can send the second information and the third information to the CU through the reference time information report message; if it is determined that the reference time information report control message does not include the first request information, it can send the second information to the CU
  • the third information is no longer sent, and the subsequent implementation can refer to the description of FIG. 3 above.
  • the DU may obtain the capability information of the DU, and determine whether the DU supports reporting the one-way transmission delay according to the capability information of the DU. If it is determined that the DU supports the reported one-way transmission delay, the second information and the third information can be sent to the CU; if it is determined that the DU does not support the reported one-way transmission delay, the second information can be sent to the CU instead of the first one.
  • Three information, follow-up implementation can refer to the description of Figure 3 above.
  • the first request information can be used to request the third information (that is, the one-way transmission delay between the DU and the terminal device), the first request information can include information instructing the DU to report the third information, and further, the first request information
  • a request message may also include the identification of the terminal device.
  • the first request information may include the identification of the terminal device. In this case, the identification of the terminal device may be used to implicitly instruct the DU to report the third information.
  • the DU After the DU receives the reference time information report control message, if it is determined that the reference time information report control message includes the first request information, it can send The CU sends the second information and the third information; if it is determined that the reference time information report control message does not include the first request information, the second information can be sent to the CU, and the third information is no longer sent.
  • the subsequent implementation can refer to Figure 3 above. description of.
  • the DU may determine that the downlink RRC transmission message includes For the first request information, the third information can be sent to the CU.
  • the DU can send the third information to the CU through an uplink RRC transmission message; and upon receiving the reference time information report control message, the second information can be sent to the CU.
  • the DU can Send the second information to the CU through the reference time information report message.
  • the DU can send the DU capability information to the CU, and the DU capability information is used to indicate whether the DU supports reporting one-way transmission delay.
  • the CU can send the first request information to the DU if it is determined that the DU supports the reporting of one-way transmission delay. If it is determined that the DU does not support the reporting of the one-way transmission delay, it can no longer Send the first request information to the DU to save resource overhead.
  • the DU can send the capability information of the DU to the CU in many ways.
  • the DU can actively report the capability information to the CU, or the DU can also report the capability information to the CU based on the instruction of the CU.
  • the DU may send the capability information to the CU through an F1 establishment response message or a DU configuration update message.
  • the first request information includes the identification of a terminal device.
  • the first request information may include the identifications of multiple terminal devices.
  • the DU may send multiple pieces of third information to the CU, and the multiple pieces of third information are respectively used to determine the one-way transmission delay between the DU and multiple terminal devices.
  • multiple pieces of third information may be carried in the same message, that is, the DU may send multiple pieces of third information to the CU at one time.
  • the identification of the terminal device may be the gNB-DU UE F1 application protocol (F1 application protocol, F1AP) identification (ID), or the identification of the terminal device may include gNB-DU UE F1AP ID and gNB- CU UE F1AP ID.
  • the gNB-DU UE F1AP ID may be the F1AP ID allocated by the DU for the terminal device
  • the gNB-CU UE F1AP ID may be the F1AP ID allocated by the CU terminal device.
  • the identification of the terminal device may also be other information used to identify the terminal device.
  • the identification of the terminal device may be a cell identifier and a cell radio network temporary identifier (C-RNTI).
  • C-RNTI cell radio network temporary identifier
  • the identification of the terminal device can be an inactive-radio network temporary identifier (I-RNTI), where I-RNTI Used to distinguish different terminal devices in a wireless notification network area.
  • the second information is used to indicate the second reference time (that is, the reference time of the DU at the reference point).
  • the time unit of the second reference time can be milliseconds, microseconds, femtoseconds, nanoseconds, or other smaller time units.
  • the embodiment of the present application does not limit the time unit of the second reference time, which is only an example here. Sexual description.
  • the second information may include a first value relative to a preset time, and optionally, may also include at least one of reference point information, time type information, and an uncertain error value. Detailed descriptions are given below.
  • the first value may include multiple time parameters corresponding to the second reference time, and the multiple time parameters may correspond to different time precisions.
  • the multiple time parameters may include a value in days (such as a), a value in seconds (such as b), a value in milliseconds (such as c), and a value in units of ten nanoseconds (such as d) relative to a preset time.
  • the second reference time is: a*86400*1000*100000+b*1000*100000+c*100000+d.
  • the time type information is used to indicate the time type of the second reference time, where the time type of the second reference time may include GPS time, coordinated universal time (UTC) time, or local time.
  • the time type of the second reference time is GPS time
  • the second reference time may be the time relative to the GPS start time (ie, the preset time) obtained by the DU from the clock source.
  • the GPS start time can be: 00:00:00 on January 6, 1980 in the Gregorian calendar.
  • the second reference time may be the time relative to the local start time (ie, the preset time) obtained by the DU from the clock source.
  • the local start time can be determined according to the local clock of the synchronization clock source.
  • the second reference time can be the relative UTC start time (ie, the preset Time) time.
  • the start time of UTC can be: 00:00:00 on January 1, 1900 in the Gregorian calendar (midnight between Sunday, December 31, 1899 and Monday, January 1, 1900).
  • the reference point information is used to indicate the reference point, and the reference point may be the start boundary or the end boundary of the radio frame.
  • the reference point information includes the reference SFN.
  • the reference point may be the start boundary or the end boundary of the radio frame corresponding to the reference SFN.
  • the second information may also include other information, which is not specifically limited.
  • the third information is used to determine the one-way transmission delay between the DU and the terminal device.
  • the third information may include at least one of the following: a first time length, a second time length, a TA value, a half of the TA value, and an adjustment amount of the TA value.
  • the third information may also include the identification of the terminal device.
  • the second time length can be half of the first time length, so the second time length can represent a one-way transmission delay.
  • the second time length can be calculated.
  • the time accuracy of the first time length or the second time length is higher than the time accuracy of the TA value.
  • the time accuracy of the first time length or the second time length may be one nanosecond or ten nanoseconds.
  • the CU may use half of the first time length as the one-way transmission delay. If the third information includes the second time length, the CU may directly use the second time length as the one-way transmission delay.
  • the TA value may be obtained according to the first time length.
  • the TA value can represent the loopback transmission delay, and half of the TA value can represent the one-way transmission delay.
  • the network device determines the first time length, and the TA value can be calculated according to the first time length.
  • the CU may use half of the TA value as the one-way transmission delay. If the third information includes half of the TA value, the CU can directly use half of the TA value as the one-way transmission delay.
  • the adjustment amount of the TA value may be the first adjustment amount or the second adjustment amount. If the third information includes the first adjustment amount, the CU may determine the TA value according to the first adjustment amount (see formula 1), and then use half of the TA value as the one-way transmission delay. If the third information includes the second adjustment value, the CU may determine the TA value (see Formula 2) according to the original TA value (ie, TAold) and the second adjustment value, and then use half of the TA value as the one-way transmission delay.
  • the third information when the third information includes the adjustment amount of the TA value, the third information may further include indication information 1, which is used to indicate that the adjustment amount of the TA value is the first adjustment amount or the second adjustment amount.
  • the indication information 1 includes 1 bit. When the value of this bit is 1, it indicates that the adjustment amount of the TA value is the first adjustment amount; when the value of the bit is 0, it indicates that the adjustment amount of the TA value is the first adjustment amount. 2. Adjust the amount.
  • two cells may be preset, namely cell 1 and cell 2, cell 1 is used to carry the first adjustment value, and cell 2 is used to carry the second adjustment value. In this case, the CU may determine the adjustment amount of the TA value as the first adjustment amount or the second adjustment amount through different cells.
  • the number of bits used to carry the cell (for example, cell 1) of the first adjustment amount may be greater than or equal to 12, and the number of bits used to carry the cell (for example, cell 2) of the second adjustment amount.
  • the number of bits included can be greater than or equal to 6.
  • the step is correspondingly smaller and the accuracy is higher, for example, for carrying
  • step 64Tc/ 2 ⁇
  • the step when the number of bits included in the cell used to carry the first adjustment is 16 is one-sixteenth of the step when the number of bits included in the cell used to carry the first adjustment is 12 , Thereby improving the time accuracy of the first adjustment amount.
  • the CU is based on the second reference time and the TA value.
  • the first reference time determined by half can also better meet the requirements of high-precision time synchronization.
  • the timing advance command (indicating the first adjustment amount) sent by the DU to the terminal device may also be greater than 12 bits, so that the time accuracy of the TA value determined by the terminal device according to the first adjustment amount is higher.
  • the timing advance command (indicating the second adjustment amount) sent by the DU to the terminal device may also be greater than 6 bits, so that the time accuracy of the TA value determined by the terminal device according to the second adjustment amount is higher.
  • step 501 is an optional step; for example, if the DU determines that the terminal device needs to perform high-precision time synchronization, it can send the second information and the third information to the CU. In this case, step 501 may not be performed. .
  • Step 503 The CU determines the first reference time according to the second reference time and the one-way transmission delay.
  • the CU may add a one-way transmission delay to the second reference time to obtain the first reference time.
  • Step 504 The CU sends first information to the terminal device, where the first information is used to indicate the first reference time.
  • the time unit of the first reference time may be milliseconds, microseconds, femtoseconds, nanoseconds, or other smaller time units.
  • the embodiment of the present application does not limit the time unit of the first reference time. This is only an illustrative description.
  • the first information indicating the realization of the first reference time may refer to the second information indicating the realization of the second reference time.
  • the first information may include multiple time parameters corresponding to the first reference time.
  • it may also include reference point information, time type information (used to indicate the time type of the first reference time), and an uncertain error value. At least one of.
  • the reference point information included in the first information and the reference point information included in the second information may be the same, the time type of the first reference time and the time type of the second reference time may be the same, and the first information includes The uncertain error value of and the uncertain error value included in the second information may be the same.
  • the first information may further include indication information 2, which is used to indicate that the reference time indicated by the first information is the reference time of the terminal device at the reference point (or the reference time on the terminal side).
  • indication information 2 may be a Boolean value. For example, when the value is true, it means that the reference time indicated by the first information is the reference time of the terminal device at the reference point; when the value is false (false) ), it means that the reference time indicated by the first information is the reference time of the DU at the reference point.
  • the CU can send the first information to the terminal device in many ways.
  • the CU can send the first information to the terminal device through an RRC message.
  • the RRC message can be an RRC reconfiguration message, a handover command, or an RRC connection resume (RRC connection resume). ) Message, RRC connection establishment message, or RRC connection re-establishment message.
  • Step 505 The terminal device receives the first information, and performs time synchronization according to the first reference time.
  • the RRC layer of the terminal device can receive the first information and determine according to the indication information 2 that the reference time indicated by the first information is the reference time of the terminal device. The reference time of the point. Further, the RRC layer of the terminal device can determine the absolute time according to the first reference time and the preset time, and can notify the upper layer (such as the non-access layer and the application layer) of the absolute time; accordingly, the application layer of the terminal device receives After the absolute time, time synchronization between the terminal device side and the network side can be realized according to the absolute time.
  • the terminal device determines that the time type of the first reference time is GPS time, it can determine the absolute time according to the first reference time and the GPS start time. For another example, if the terminal device determines that the time type of the first reference time is local time, it may determine the absolute time according to the first reference time and the local start time. It should be noted that if the first information includes an uncertain error value, the terminal device may determine the absolute time according to the first reference time, the preset time, and the uncertain error value.
  • the DU can send the second information and the third information to the CU, and then the CU can determine the reference time of the terminal device at the reference point according to the second information and the third information, and send the reference time of the terminal device at the reference point to
  • the terminal device can effectively reduce the processing complexity of time synchronization of the terminal device and save the power consumption of the terminal device.
  • the terminal determined by the CU is The reference time of the device at the reference point can better meet the requirements of high-precision time synchronization; or, when the third information includes the adjustment amount of the TA value, the number of bits included in the cell carrying the adjustment amount of the TA value may be greater than 12 ( Or greater than 6), thereby improving the time accuracy of the adjustment of the TA value, so that the reference time of the terminal device at the reference point determined by the CU can better meet the requirements of high-precision time synchronization.
  • the CU can send the reference time of the terminal device at the reference point to the terminal device through high-level signaling (such as an RRC message), it can effectively ensure the security of information transmission.
  • FIG. 6 is a schematic flowchart corresponding to the time synchronization method provided in the second embodiment of this application. As shown in Figure 6, it includes:
  • Step 601 The CU sends second request information to the DU.
  • the second request information can be used to request the reference time of the terminal device at the reference point, or the second request information is used to request the DU to report the reference time of the terminal device at the reference point;
  • Ground, the DU receives the second request information.
  • the second request information may be carried in a reference time information report control message, or a downlink RRC transmission message, or a context establishment request message of a terminal device, or a context modification request message of a terminal device.
  • the second request information may include information instructing the DU to report the reference time of the terminal device at the reference point (for ease of description, referred to as indication information 3), further, the second request information may also include The identification of the terminal device.
  • the indication information 3 can be a Boolean value. When the value is true, it instructs the DU to report the reference time of the terminal device at the reference point; when the value is false, it instructs the DU to report the reference time of the DU at the reference point. . Further, when the value of the indication information 3 is true, the second request information may further include the identification of the terminal device, and when the value of the indication information 3 is false, the second request information may no longer include the identification of the terminal device.
  • the DU receives the reference time information report control message, and if it is determined that the reference time information report control message includes indication information 3 (the value of indication information 3 is true) and the terminal The identification of the device, it can be learned that the CU requests the reference time of the terminal device at the reference point. If the reference time information report control message includes indication information 3 (the value of indication information 3 is false), it can be learned that the CU is requesting DU The reference time at the reference point.
  • the indication information 3 may include a bit. When the value of this bit is 1, it instructs the DU to report the reference time of the terminal equipment at the reference point; when the value of the bit is 0, it instructs the DU to report the DU at the reference point. The reference time of the reference point. Further, when the value of the indication information 3 is 1, the second request information may also include the identification of the terminal device, and when the value of the indication information 3 is 0, the second request information may no longer include the identification of the terminal device.
  • the DU receives the reference time information report control message, if it is determined that the reference time information report control message includes indication information 3 (the value of indication information 3 is 1) and the terminal The identification of the device, it can be learned that the CU requested the reference time of the terminal device at the reference point. If the reference time information report control message includes indication information 3 (the value of the indication information 3 is 0), it can be learned that the CU requested the DU The reference time at the reference point.
  • the second request information when the second request information includes indication information 3, instruct the DU to report the reference time of the terminal device at the reference point; when the second request information does not include indication information 3, instruct the DU to report the reference time of the DU at the reference point .
  • the second request information when the second request information includes the indication information 3, the second request information may also include the identification of the terminal device; when the second request information does not include the indication information 3, the second request information may no longer include the identification of the terminal device .
  • the DU receives the reference time information report control message, and if it is determined that the reference time information report control message includes the indication information 3 and the identification of the terminal device, it can learn the request of the CU It is the reference time of the terminal device at the reference point. If it is determined that the reference time information report control message does not include the indication information 3 and the identification of the terminal device, it can be learned that the CU requests the reference time of the DU at the reference point.
  • the second request information includes the identification of the terminal device.
  • the identification of the terminal device may be used to implicitly instruct the DU to report the reference time of the terminal device at the reference point.
  • the DU receives the reference time information report control message, and if it is determined that the reference time information report control message includes the identification of the terminal device, it can be learned that the CU requested the terminal The reference time of the device at the reference point, if it is determined that the reference time information report control message does not include the identification of the terminal device, it can be learned that what the CU requests is the reference time of the DU at the reference point.
  • Step 602 The DU determines a first reference time, where the first reference time is the reference time of the terminal device at the reference point.
  • the DU can obtain the reference time of the DU at the reference point and the one-way transmission delay between the DU and the terminal device, and then determine the reference time of the terminal device at the reference point according to the reference time of the DU at the reference point and the one-way transmission delay Reference time.
  • the implementation of obtaining the reference time of the DU at the reference point by the DU can refer to the description in Embodiment 1.
  • the DU can obtain the time relative to the GPS start time from the clock source as the reference time of the DU at the reference point;
  • the DU may obtain the time relative to the local start time obtained from the clock source as the reference time of the DU at the reference point.
  • the DU can obtain the first time length, and use half of the first time length as the single transmission time between the DU and the terminal device.
  • the DU can obtain the TA value, and use half of the TA value as the one-way transmission delay between the DU and the terminal device.
  • the manner in which the DU obtains the first time length or the TA value can refer to the description in the foregoing.
  • step 601 is an optional step; for example, if the DU determines that the terminal device needs to perform high-precision time synchronization, it can determine the reference time of the terminal device at the reference point. In this case, step 601 may not be performed.
  • Step 603 The DU sends fourth information to the CU.
  • the fourth information is used to indicate the reference time of the terminal device at the reference point (may be referred to as the first reference time); accordingly, the CU receives the fourth information.
  • the fourth information may be carried in any of the following messages: a reference time information report message, an initial uplink RRC transmission message, an uplink RRC transmission message, a context establishment response message of the terminal device, or a context modification response message of the terminal device.
  • the fourth information may include multiple time parameters corresponding to the first reference time; further, the fourth information may also include the identification of the terminal device.
  • the fourth information may further include at least one of the following: time type information (a time type used to indicate the first reference time), reference point information, and an uncertain error value.
  • Step 604 The CU sends the first information to the terminal device.
  • the first information may include multiple time parameters corresponding to the first reference time.
  • it may also include reference point information, time type information (used to indicate the time type of the first reference time), and uncertain errors. At least one of the values.
  • multiple time parameters, reference point information, time type information, and uncertain error values corresponding to the first reference time included in the first information may respectively correspond to multiple times corresponding to the first reference time included in the fourth information.
  • the parameters, reference point information, time type information, and uncertain error values are the same.
  • step 604 For the specific implementation of step 604, reference may be made to the related description of step 504 in the first embodiment, which will not be repeated.
  • Step 605 The terminal device receives the first information, and performs time synchronization according to the first reference time.
  • step 605 For the specific implementation of step 605, reference may be made to the related description of step 504 in the first embodiment, which will not be repeated.
  • the DU can determine the reference time of the terminal device at the reference point, and send the reference time of the terminal device at the reference point to the CU, and then the CU to the terminal device, which can effectively reduce the processing complexity of the terminal device for time synchronization ,
  • determining the first reference time through the DU can effectively reduce the processing burden of the CU
  • the DU can determine the one-way transmission delay through the first time length to determine the terminal
  • the reference time of the device at the reference point because the time accuracy of the first time length is relatively high, so that the determined reference time of the terminal device at the reference point can better meet the requirements of high-precision time synchronization.
  • FIG. 7 is a schematic flowchart corresponding to the time synchronization method provided in Embodiment 3 of this application. As shown in Figure 7, it includes:
  • Step 701 The CU sends the third request information to the DU, and accordingly, the DU receives the third request information.
  • the third request information may include the identification of the terminal device, and the third request information is used to request the DU to send the terminal device's reference time at the reference point (ie, the first reference time) to the terminal device.
  • the reference point ie, the first reference time
  • Step 702 The DU determines a first reference time, where the first reference time is the reference time of the terminal device at the reference point.
  • the first reference time is the reference time of the terminal device at the reference point.
  • Step 703 The DU sends fifth information to the terminal device, where the fifth information is used to indicate the first reference time.
  • the DU may send the fifth information to the terminal device through MAC CE or DCI.
  • the content included in the fifth information may be the same as the content included in the first information described in the first embodiment, and the details are not repeated here.
  • Step 704 The terminal device receives the fifth information, and performs time synchronization according to the first reference time.
  • the DU determines the first reference time and sends it to the terminal device, thereby effectively improving the transmission efficiency and reducing the signaling overhead between the CU and the DU.
  • step numbers of the flowcharts described in Embodiment 1 to Embodiment 3 are only an example of the execution process, and do not constitute a restriction on the order of execution of the steps. There is no time sequence dependency among the embodiments of this application. There is no strict order of execution between the steps of the relationship. In addition, not all the steps shown in the flowcharts are necessary steps. Some steps can be added or deleted based on the flowcharts according to actual needs. For example, the above steps 501, 601, and 701 can be selectively performed. .
  • the CU or DU may include hardware structures and/or software modules corresponding to the respective functions.
  • the embodiments of the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a certain function is executed by hardware or computer software-driven hardware depends on the specific application and design constraint conditions of the technical solution. Professionals and technicians can use different methods for each specific application to implement the described functions, but such implementation should not be considered beyond the scope of this application.
  • the embodiment of the present application may divide the CU or DU into functional units according to the foregoing method examples.
  • each functional unit may be divided corresponding to each function, or two or more functions may be integrated into one unit.
  • the above-mentioned integrated unit can be implemented in the form of hardware or software functional unit.
  • FIG. 8 shows a possible exemplary block diagram of a device involved in an embodiment of the present application.
  • the apparatus 800 may include: a processing unit 802 and a communication unit 803.
  • the processing unit 802 is used to control and manage the actions of the device 800.
  • the communication unit 803 is used to support communication between the apparatus 800 and other devices.
  • the communication unit 803 is also called a transceiving unit, and may include a receiving unit and/or a sending unit, which are used to perform receiving and sending operations, respectively.
  • the device 800 may further include a storage unit 801 for storing program codes and/or data of the device 800.
  • the apparatus 800 may be the CU in any of the foregoing embodiments, or may also be a chip provided in the CU.
  • the processing unit 802 may support the device 800 to perform the actions of the CU in the above method examples.
  • the processing unit 802 mainly executes the internal actions of the CU in the method example, and the communication unit 803 may support communication between the apparatus 800 and other devices (such as DU).
  • the processing unit 802 is configured to determine a first reference time, where the first reference time is a reference time of the terminal device at a reference point; the communication unit 803 is configured to send first information to the terminal device, One piece of information is used to indicate the first reference time.
  • the communication unit 803 is further configured to receive second information and third information from the DU; where the second information is used to indicate a second reference time, and the second reference time is the reference time of the DU.
  • the third information is used to determine the one-way transmission delay between the DU and the terminal device; the processing unit 802 is specifically configured to determine the first reference time according to the second reference time and the one-way transmission delay.
  • the communication unit 803 is specifically configured to send first request information to the DU, the first request information is used to request the one-way transmission delay, and the first request information includes the identification of the terminal device; And, receiving the third information sent by the DU according to the first request information.
  • the communication unit 803 is further configured to receive capability information from the DU, where the capability information is used to indicate that the DU supports reporting the one-way transmission delay.
  • the third information includes at least one of the following: (1) a first time length, the first time length characterizing the loopback transmission delay between the DU and the terminal device; the first time The length is obtained by measuring the first uplink signal or the second uplink signal sent by the terminal equipment; the first uplink signal is a random access preamble, and the second uplink signal is different from the first uplink signal; (2) the second time Length, the second time length is half of the first time length; (3) the TA value of the terminal device; (4) half of the TA value; (5) the adjustment amount corresponding to the TA value; The time accuracy of the one time length or the second time length is higher than the time accuracy of the TA value.
  • the communication unit 803 is further configured to receive fourth information from the DU, where the fourth information is used to indicate the first reference time.
  • the communication unit 803 is specifically configured to send second request information to the DU, the second request information is used to request the first reference time, and the second request information includes the identification of the terminal device; and, to receive the DU sent The fourth message.
  • the device 800 may be the DU in any of the foregoing embodiments, or may also be a chip set in the DU.
  • the processing unit 802 may support the device 800 to perform the actions of the DU in the foregoing method examples.
  • the processing unit 802 mainly executes the internal actions of the DU in the method example, and the communication unit 803 may support communication between the apparatus 800 and other devices (such as a CU).
  • the processing unit 802 is configured to determine second information and third information; wherein, the second information is used to indicate a second reference time, and the second reference time is the time when the DU is at the reference point
  • the third information is used to determine the one-way transmission delay between the DU and the terminal device;
  • the communication unit 803 is used to send the second information and the third information to the CU.
  • the communication unit 803 is specifically configured to receive first request information from the CU, the first request information is used to request the DU to report the one-way transmission delay, and the first request information includes the The identifier of the terminal device; and, sending third information to the CU according to the first request information.
  • the communication unit 803 is further configured to send capability information of the DU to the CU, where the capability information is used to indicate that the DU supports reporting the one-way transmission delay.
  • the communication unit 803 is specifically configured to receive the first request information from the CU, the first request information is used to request the second information and the third information, and the first request information includes the identification of the terminal device; and After the processing unit 802 determines that it supports reporting the one-way transmission delay, the second information and the third information are sent to the CU.
  • the third information includes at least one of the following: (1) a first time length, the first time length characterizing the loopback transmission delay between the DU and the terminal device; the first time The length is obtained by measuring the first uplink signal or the second uplink signal sent by the terminal equipment; the first uplink signal is a random access preamble, and the second uplink signal is different from the first uplink signal; (2) the second time Length, the second time length is half of the first time length; (3) the timing advance TA value of the terminal device; (4) half of the TA value; (5) the adjustment amount corresponding to the TA value; wherein , The time accuracy of the first time length or the second time length is higher than the time accuracy of the TA value.
  • the processing unit 802 is configured to determine a first reference time, where the first reference time is the reference time of the terminal device at the reference point;
  • the communication unit 803 is configured to send fourth information to the CU, the first The four information is used to indicate the first reference time.
  • the communication unit 803 is specifically configured to receive second request information from the CU, the second request information is used to request the first reference time, and the second request information includes the identification of the terminal device; and, according to the second The request message sends the fourth message to the CU.
  • the processing unit 802 is specifically configured to determine a second reference time, where the second reference time is the reference time of the DU at the reference point; and, to determine the second time length, the second time length Characterize the one-way transmission delay between the DU and the terminal device; wherein the time accuracy of the second time length is higher than the time accuracy of the TA value of the terminal device; according to the second reference time and the one-way The transmission delay determines the first reference time.
  • each unit in the device can be all implemented in the form of software called by processing elements; they can also be all implemented in the form of hardware; part of the units can also be implemented in the form of software called by the processing elements, and some of the units can be implemented in the form of hardware.
  • each unit can be a separate processing element, or it can be integrated in a certain chip of the device for implementation.
  • it can also be stored in the memory in the form of a program, which is called and executed by a certain processing element of the device. Function.
  • each step of the above method or each of the above units may be implemented by an integrated logic circuit of hardware in a processor element or implemented in a form of being called by software through a processing element.
  • the unit in any of the above devices may be one or more integrated circuits configured to implement the above method, for example: one or more application specific integrated circuits (ASIC), or, one or Multiple microprocessors (digital singnal processors, DSPs), or, one or more field programmable gate arrays (Field Programmable Gate Arrays, FPGAs), or a combination of at least two of these integrated circuit forms.
  • ASIC application specific integrated circuits
  • DSPs digital singnal processors
  • FPGAs Field Programmable Gate Arrays
  • the unit in the device can be implemented in the form of a processing element scheduler
  • the processing element can be a processor, such as a general-purpose central processing unit (central processing unit, CPU), or other processors that can call programs.
  • CPU central processing unit
  • these units can be integrated together and implemented in the form of a system-on-a-chip (SOC).
  • the above receiving unit is an interface circuit of the device for receiving signals from other devices.
  • the receiving unit is an interface circuit used by the chip to receive signals from other chips or devices.
  • the above unit for sending is an interface circuit of the device for sending signals to other devices.
  • the sending unit is an interface circuit used by the chip to send signals to other chips or devices.
  • FIG. 9 is a schematic structural diagram of a network device provided by an embodiment of this application.
  • the network device (or base station) can be applied to the system architecture shown in FIG. 1.
  • the network device includes one or more DU 901 and one or more CU 902.
  • the DU 901 can be used to perform the function of the DU in the foregoing method embodiment
  • the CU 902 can be used to perform the function of the CU in the foregoing method embodiment.
  • the DU 901 may include at least one antenna 9011, at least one radio frequency unit 9012, at least one processor 9013, and at least one memory 9014.
  • the DU 901 part is mainly used for the transmission and reception of radio frequency signals, the conversion of radio frequency signals and baseband signals, and part of baseband processing.
  • the CU 902 may include at least one processor 9022 and at least one memory 9021.
  • CU902 and DU901 can communicate through F1 interface (such as F1-C or F1-U).
  • the CU 902 part is mainly used for baseband processing and so on.
  • the DU 901 and the CU 902 may be physically set together, or may be physically separated. In the embodiment of the present application, the DU 901 and the CU 902 are physically separated and described as an example.
  • the network device 90 may include one or more radio frequency units, one or more DUs, and one or more CUs.
  • the DU may include at least one processor 9013 and at least one memory 9014
  • the radio frequency unit may include at least one antenna 9011 and at least one radio frequency unit 9012
  • the CU may include at least one processor 9022 and at least one memory 9021.
  • the CU902 can be composed of one or more single boards, and multiple single boards can jointly support a wireless access network (such as a 5G network) with a single access indication, or can respectively support wireless access networks of different access standards.
  • Access network (such as LTE network, 5G network or other network).
  • the memory 9021 and the processor 9022 may serve one or more single boards; that is to say, each single board may be separately provided with a memory and a processor, or multiple single boards may share the same memory and processor .
  • necessary circuits can be provided on each board.
  • the DU901 can be composed of one or more single boards.
  • Multiple single boards can jointly support a wireless access network with a single access indication (such as a 5G network), and can also support wireless access networks with different access standards (such as LTE network, 5G network or other network).
  • the memory 9014 and the processor 9013 may serve one or more single boards. In other words, each single board may be separately provided with a memory and a processor, or multiple single boards may share the same memory and processor. In addition, necessary circuits can be provided on each board.
  • the CU shown in FIG. 9 can implement various processes related to the CU in the method embodiment shown in FIG. 5 or FIG. 6 or FIG. 7.
  • the operations and/or functions of the various modules in the CU shown in FIG. 9 are used to implement the corresponding processes in the foregoing method embodiments.
  • the DU shown in FIG. 9 can implement various processes related to the DU in the method embodiment shown in FIG. 5 or FIG. 6 or FIG. 7.
  • the operations and/or functions of each module in the DU shown in FIG. 9 are used to implement the corresponding processes in the foregoing method embodiments.
  • system and “network” in the embodiments of this application can be used interchangeably.
  • At least one means one or more, and “plurality” means two or more.
  • And/or describes the association relationship of the associated objects, indicating that there can be three types of relationships, for example, A and/or B, which can mean: the existence of A alone, both A and B, and B alone, where A, B can be singular or plural.
  • the character “/” generally indicates that the associated objects before and after are in an “or” relationship.
  • “The following at least one item (a)” or similar expressions refers to any combination of these items, including any combination of a single item (a) or a plurality of items (a).
  • At least one of A, B, and C includes A, B, C, AB, AC, BC, or ABC.
  • the ordinal numbers such as “first” and “second” mentioned in the embodiments of this application are used to distinguish multiple objects, and are not used to limit the order, timing, priority, or importance of multiple objects. degree.
  • this application can be provided as methods, systems, or computer program products. Therefore, this application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, this application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.
  • computer-usable storage media including but not limited to disk storage, CD-ROM, optical storage, etc.
  • These computer program instructions can also be stored in a computer-readable memory that can guide a computer or other programmable data processing equipment to work in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture including the instruction device.
  • the device implements the functions specified in one process or multiple processes in the flowchart and/or one block or multiple blocks in the block diagram.
  • These computer program instructions can also be loaded on a computer or other programmable data processing equipment, so that a series of operation steps are executed on the computer or other programmable equipment to produce computer-implemented processing, so as to execute on the computer or other programmable equipment.
  • the instructions provide steps for implementing the functions specified in one process or multiple processes in the flowchart and/or one block or multiple blocks in the block diagram.

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Abstract

本申请涉及通信技术领域，公开了一种时间同步方法及装置。其中方法包括：CU确定终端设备在参考点的参考时间，并向终端设备发送第一信息，第一信息用于指示终端设备在参考点的参考时间；进而终端设备接收到第一信息后，可以根据终端设备在参考点的参考时间进行时间同步。采用该种方式，终端设备可以从CU获取到终端设备在参考点的参考时间，能够有效降低终端设备的处理复杂度，节省终端设备的功耗。

Description

一种时间同步方法及装置
相关申请的交叉引用
本申请要求在2020年04月15日提交中国专利局、申请号为202010297025.8、申请名称为“一种时间同步方法及装置”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及通信技术领域，尤其涉及一种时间同步方法及装置。
背景技术
移动互联网和物联网作为未来通信发展的主要驱动力，在人们的居住、工作、休闲和交通等领域产生了巨大影响。目前，为了实现业务的精准控制，在工业控制、智能电网、无人驾驶等多个领域要求终端设备和无线网络侧进行高精度的时间同步。
在第五代(the 5 th generation，5G)通信系统中，无线网络侧的接入网设备可以包括分离的节点，比如集中式单元(central unit，CU)和分布式单元(distributed unit，DU)。在此种场景下，如何降低终端设备进行时间同步的复杂度，仍需进一步的研究。
发明内容
本申请提供了一种时间同步方法及装置，用以降低终端设备进行时间同步的复杂度。
第一方面，本申请实施例提供了一种时间同步方法，该方法可以适用于第一通信装置，第一通信装置为CU或CU中的芯片。以该方法适用于CU为例，在该方法中，CU确定第一参考时间，第一参考时间为终端设备在参考点的参考时间；以及，向终端设备发送第一信息，第一信息用于指示第一参考时间。
采用该种方式，终端设备可以从CU获取到终端设备在参考点的参考时间，相比于现有方案中，终端设备根据从CU获取的DU侧的参考时间以及终端设备和DU之间的单向传输时延来确定终端设备在参考点的参考时间的方案来说，能够有效降低终端设备的处理复杂度，节省终端设备的功耗。
在一种可能的设计中，CU确定第一参考时间，可以是指：CU接收来自DU的第二信息和第三信息；其中，第二信息用于指示第二参考时间，第二参考时间为所述DU在所述参考点的参考时间，第三信息用于确定所述DU和所述终端设备之间的单向传输时延；以及，CU根据第二参考时间和所述单向传输时延确定第一参考时间。
在一种可能的设计中，CU接收来自DU的第三信息，可以是指：CU向DU发送第一请求信息，第一请求信息用于请求所述单向传输时延，第一请求信息包括所述终端设备的标识；以及接收DU发送的第三信息。
在一种可能的设计中，第一请求信息承载于参考时间信息报告控制消息、或者下行RRC传输消息、或者终端设备的上下文建立请求消息、或者终端设备的上下文修改请求消息。
在一种可能的设计中，该方法还包括：CU接收来自所述DU的能力信息，所述能力信息用于指示所述DU支持上报所述单向传输时延。
如此，CU可以根据DU的能力信息确定DU支持上报所述单向传输时延后，向DU发送第一请求信息，若确定DU不支持上报单向传输时延，则可以不再向DU发送第一请求信息，以节省资源开销。
在一种可能的设计中，第三信息包括以下至少一项：(1)第一时间长度，第一时间长度表征所述DU和所述终端设备之间的环回传输时延；第一时间长度是通过测量所述终端设备发送的第一上行信号或第二上行信号得到的；第一上行信号为随机接入前导码，第二上行信号不同于第一上行信号；(2)第二时间长度，第二时间长度为第一时间长度的一半；(3)所述终端设备的定时提前TA值；(4)所述TA值的一半；(5)所述TA值对应的调整量。
在一种可能的设计中，第一时间长度或第二时间长度的时间精度高于所述TA值的时间精度。
如此，由于第一时间长度或第二时间长度的时间精度高于TA值的时间精度，从而使得CU确定出的终端设备在参考点的参考时间更能符合高精度时间同步的需求。
在一种可能的设计中，第一时间长度或第二时间长度的时间精度为纳秒或十纳秒。
在一种可能的设计中，当第三信息包括所述TA值对应的调整量时，该方法还包括：若所述TA值对应的调整量为第一调整量，则CU根据第一调整量确定所述TA值，进而根据所述TA值确定所述单向传输时延；或者，若所述TA值对应的调整量为第二调整量，则CU根据原TA值和第二调整量确定所述TA值，进而所述TA值确定所述单向传输时延。
在一种可能的设计中，用于承载第一调整量的信元所包括的比特数目大于12；或者，用于承载第二调整量的信元所包括的比特数目大于6。
如此，能够有效提高TA值的调整量的时间精度，使得CU确定出的终端设备在参考点的参考时间更能符合高精度的时间同步的需求。
在一种可能的设计中，第三信息还包括所述终端设备的标识。
在一种可能的设计中，CU确定第一参考时间，可以是指：CU接收来自DU的第四信息，第四信息用于指示第一参考时间。
在一种可能的设计中，CU接收来自DU的第四信息，可以是指：CU向DU发送第二请求信息，第二请求信息用于请求第一参考时间，第二请求信息包括终端设备的标识；以及，接收所述DU发送的所述第四信息。
在一种可能的设计中，CU接收来自DU的第四信息，可以是指：CU向DU发送参考时间信息报告控制消息，所述参考时间信息报告控制消息包括所述终端设备的标识；以及，接收DU发送的第四信息。
在一种可能的设计中，参考时间信息报告控制消息还包括指示信息，指示信息用于指示所述参考时间信息报告控制消息所请求的参考时间为终端设备在参考点的参考时间。
在一种可能的设计中，第一信息包括第一参考时间对应的多个时间参数。
在一种可能的设计中，第一信息还包括以下至少一项：(1)参考点信息，用于指示所述参考点；(2)时间类型信息，用于指示第一参考时间的时间类型；(3)不确定的误差值。
在一种可能的设计中，第一信息承载于RRC消息。
如此，由于CU可以通过高层信令(比如RRC消息)向终端设备发送第一信息，从而 能够有效保证信息传输的安全性。
第二方面，本申请实施例提供了一种时间同步方法，该方法可以适用于第二通信装置，第二通信装置为DU或DU中的芯片。以该方法适用于DU为例，在该方法中，DU确定第二信息和第三信息，并向CU发送第二信息和第三信息；其中，第二信息用于指示第二参考时间，第二参考时间为DU在所述参考点的参考时间，第三信息用于确定所述DU和终端设备之间的单向传输时延。
在一种可能的设计中，DU向CU发送第三信息，可以是指：DU接收来自CU的第一请求信息，第一请求信息用于请求所述单向传输时延，第一请求信息包括所述终端设备的标识；以及DU根据第一请求信息向所述CU发送第三信息。
在一种可能的设计中，第一请求信息承载于参考时间信息报告控制消息、或者下行RRC传输消息、或者终端设备的上下文建立请求消息、或者终端设备的上下文修改请求消息。
在一种可能的设计中，该方法还包括：DU向CU发送DU的能力信息，所述能力信息用于指示DU支持上报所述单向传输时延。
在一种可能的设计中，DU向CU发送第二信息和第三信息，可以是指：DU接收来自CU的第一请求信息，第一请求信息用于请求第二信息和第三信息，第一请求信息包括终端设备的标识；以及，DU确定支持上报所述单向传输时延后，向CU发送第二信息和第三信息。
在一种可能的设计中，第三信息包括以下至少一项：(1)第一时间长度，第一时间长度表征所述DU和所述终端设备之间的环回传输时延；第一时间长度是通过测量所述终端设备发送的第一上行信号或第二上行信号得到的；第一上行信号为随机接入前导码，第二上行信号不同于第一上行信号；(2)第二时间长度，第二时间长度为第一时间长度的一半；(3)所述终端设备的TA值；(4)所述TA值的一半；(5)所述TA值对应的调整量。
在一种可能的设计中，第一时间长度或第二时间长度的时间精度高于所述TA值的时间精度。
在一种可能的设计中，第一时间长度或第二时间长度的时间精度为纳秒或十纳秒。
在一种可能的设计中，所述TA值对应的调整量为第一调整量或第二调整量；其中，用于承载第一调整量的信元所包括的比特数目大于12；或者，用于承载第二调整量的信元所包括的比特数目大于6。
在一种可能的设计中，第三信息还包括所述终端设备的标识。
第三方面，本申请实施例提供了一种时间同步方法，该方法可以适用于第二通信装置，第二通信装置为DU或DU中的芯片。以该方法适用于DU为例，在该方法中，DU确定第一参考时间，并向CU发送第四信息，第四信息用于指示第一参考时间，第一参考时间为终端设备在参考点的参考时间。
在一种可能的设计中，DU向CU发送第四信息，包括：接收来自CU的第二请求信息，第二请求信息用于请求第一参考时间，第二请求信息包括终端设备的标识；根据第二请求信息向CU发送第四信息。
在一种可能的设计中，DU向CU发送第四信息，包括：接收来自CU的参考时间信息报告控制消息，参考时间信息报告控制消息包括终端设备的标识；根据参考时间信息报告控制消息向CU发送第四信息。
在一种可能的设计中，参考时间信息报告控制消息还包括指示信息，指示信息用于指示参考时间信息报告控制消息所请求的参考时间为终端设备在参考点的参考时间。
在一种可能的设计中，DU确定第一参考时间，包括：DU确定第二参考时间，第二参考时间为所述DU在所述参考点的参考时间；以及，确定所述DU和所述终端设备之间的单向传输时延；进而，DU根据第二参考时间和所述单向传输时延确定第一参考时间。
在一种可能的设计中，DU确定所述单向传输时延，可以是指：DU通过测量终端设备发送的第一上行信号或第二上行信号得到第一时间长度，第一上行信号为随机接入前导码，第二上行信号不同于第一上行信号；第一时间长度表征DU和终端设备之间的环回传输时延；以及，根据第一时间长度确定所述单向传输时延；或者，DU确定终端设备的TA值，根据所述TA值确定所述单向传输时延。
在一种可能的设计中，第一时间长度的时间精度高于所述TA值的时间精度。
在一种可能的设计中，第一时间长度的时间精度为纳秒或十纳秒。
第四方面，本申请实施例提供了一种时间同步方法，该方法可以适用于第三通信装置，第三通信装置为终端设备或终端设备中的芯片。以该方法适用于终端设备为例，在该方法中，终端设备接收第一信息，第一信息用于指示第一参考时间，第一参考时间为终端设备在参考点的参考时间；进而，根据第一参考时间进行时间同步。
在一种可能的设计中，终端设备可以接收来自CU或DU的第一信息。
上述第二方面、第三方面和第四方面所描述的时间同步方法与第一方面所描述的时间同步方法相对应，相关技术特征的有益效果均可参见第一方面的描述。
第五方面，本申请提供一种通信装置，所述通信装置可以为CU或者设置在CU内部的芯片。所述通信装置具备实现上述第一方面的功能，比如，所述通信装置包括执行上述第一方面涉及步骤所对应的模块或单元或手段(means)，所述功能或单元或手段可以通过软件实现，或者通过硬件实现，也可以通过硬件执行相应的软件实现。
在一种可能的设计中，所述通信装置包括处理单元、通信单元，其中，通信单元可以用于收发信号，以实现该通信装置和其它装置之间的通信，比如，通信单元用于接收来自网络设备的配置信息；处理单元可以用于执行该通信装置的一些内部操作。处理单元、通信单元执行的功能可以和上述第一方面涉及的步骤相对应。
在一种可能的设计中，所述通信装置包括处理器，还可以包括收发器，所述收发器用于收发信号，所述处理器执行程序指令，以完成上述第一方面中任意可能的设计或实现方式中的方法。其中，所述通信装置还可以包括一个或多个存储器，所述存储器用于与处理器耦合。所述一个或多个存储器可以和处理器集成在一起，也可以与处理器分离设置，本申请并不限定。存储器可以保存实现上述第一方面涉及的功能的必要计算机程序或指令。所述处理器可执行所述存储器存储的计算机程序或指令，当所述计算机程序或指令被执行时，使得所述通信装置实现上述第一方面任意可能的设计或实现方式中的方法。
在一种可能的设计中，所述通信装置包括处理器和存储器，存储器可以保存实现上述第一方面涉及的功能的必要计算机程序或指令。所述处理器可执行所述存储器存储的计算机程序或指令，当所述计算机程序或指令被执行时，使得所述通信装置实现上述第一方面任意可能的设计或实现方式中的方法。
在一种可能的设计中，所述通信装置包括至少一个处理器和接口电路，其中，至少一个处理器用于通过所述接口电路与其它装置通信，并执行上述第一方面任意可能的设计或 实现方式中的方法。
第六方面，本申请提供一种通信装置，所述通信装置可以为DU或者设置在DU内部的芯片。所述通信装置具备实现上述第二方面或第三方面涉及的功能，比如，所述通信装置包括执行上述第二方面或第三方面涉及步骤所对应的模块或单元或手段，所述功能或单元或手段可以通过软件实现，或者通过硬件实现，也可以通过硬件执行相应的软件实现。
在一种可能的设计中，所述通信装置包括处理单元、通信单元，其中，通信单元可以用于收发信号，以实现该通信装置和其它装置之间的通信，比如，通信单元用于向终端设备发送系统信息；处理单元可以用于执行该通信装置的一些内部操作。处理单元、通信单元执行的功能可以和上述第二方面或第三方面涉及的步骤相对应。
在一种可能的设计中，所述通信装置包括处理器，还可以包括收发器，所述收发器用于收发信号，所述处理器执行程序指令，以完成上述第二方面或第三方面中任意可能的设计或实现方式中的方法。其中，所述通信装置还可以包括一个或多个存储器，所述存储器用于与处理器耦合。所述一个或多个存储器可以和处理器集成在一起，也可以与处理器分离设置，本申请并不限定。存储器可以保存实现上述第二方面或第三方面涉及的功能的必要计算机程序或指令。所述处理器可执行所述存储器存储的计算机程序或指令，当所述计算机程序或指令被执行时，使得所述通信装置实现上述第二方面或第三方面任意可能的设计或实现方式中的方法。
在一种可能的设计中，所述通信装置包括处理器和存储器，存储器可以保存实现上述第二方面或第三方面涉及的功能的必要计算机程序或指令。所述处理器可执行所述存储器存储的计算机程序或指令，当所述计算机程序或指令被执行时，使得所述通信装置实现上述第二方面或第三方面任意可能的设计或实现方式中的方法。
在一种可能的设计中，所述通信装置包括至少一个处理器和接口电路，其中，至少一个处理器用于通过所述接口电路与其它装置通信，并执行上述第二方面或第三方面任意可能的设计或实现方式中的方法。
第七方面，本申请提供一种通信系统，该通信系统可以包括上述第五方面所述的通信装置和上述第六方面所述的通信装置。在一种可能的设计中，该通信系统还可以包括终端设备。
第八方面，本申请提供一种计算机可读存储介质，所述计算机存储介质中存储有计算机可读指令，当计算机读取并执行所述计算机可读指令时，使得计算机执行上述第一方面至第四方面的任一种可能的设计中的方法。
第九方面，本申请提供一种计算机程序产品，当计算机读取并执行所述计算机程序产品时，使得计算机执行上述第一方面至第四方面的任一种可能的设计中的方法。
第十方面，本申请提供一种芯片，所述芯片包括处理器，所述处理器与存储器耦合，用于读取并执行所述存储器中存储的软件程序，以实现上述第一方面至第四方面的任一种可能的设计中的方法。
附图说明
图1为本申请实施例适用的一种网络架构示意图；
图2a为本申请实施例提供的下行数据在各层间传输示意图；
图2b为本申请实施例提供的一种CU-DU分离架构的示意图；
图2c为本申请实施例提供的另一种CU-DU分离架构的示意图；
图2d为本申请实施例提供的另一种CU-DU分离架构的示意图；
图3为本申请实施例提供的终端设备和无线网络侧进行高精度的时间同步的流程示意图；
图4为本申请实施例提供的上行时间调整示意图；
图5为本申请实施例一提供的时间同步方法所对应的流程示意图；
图6为本申请实施例二提供的时间同步方法所对应的流程示意图；
图7为本申请实施例三提供的时间同步方法所对应的流程示意图；
图8为本申请实施例中所涉及的装置的可能的示例性框图；
图9为本申请实施例提供的一种网络设备的结构示意图。
具体实施方式
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述。
图1为本申请实施例适用的一种网络架构示意图。如图1所示，终端设备(比如终端设备1301或终端设备1302)可接入到无线网络，以通过无线网络获取外网(例如因特网)的服务，或者通过无线网络与其它设备通信，如可以与其它终端设备通信。该无线网络包括无线接入网(radio access network，RAN)和核心网(core network，CN)，其中，RAN用于将终端设备接入到无线网络，CN用于对终端设备进行管理并提供与外网通信的网关。
下面分别对图1中所涉及的终端设备、RAN和CN进行详细说明。
一、终端设备
终端设备包括向用户提供语音和/或数据连通性的设备，例如可以包括具有无线连接功能的手持式设备、或连接到无线调制解调器的处理设备。该终端设备可以经无线接入网(radio access network，RAN)与核心网进行通信，与RAN交换语音和/或数据。该终端设备可以包括用户设备(user equipment，UE)、无线终端设备、移动终端设备、设备到设备通信(device-to-device，D2D)终端设备、车到一切(vehicle to everything，V2X)终端设备、机器到机器/机器类通信(machine-to-machine/machine-type communications，M2M/MTC)终端设备、物联网(internet of things，IoT)终端设备、订户单元(subscriber unit)、订户站(subscriber station)，移动站(mobile station)、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。例如，可以包括移动电话(或称为“蜂窝”电话)，具有移动终端设备的计算机，便携式、袖珍式、手持式、计算机内置的移动装置等。例如，个人通信业务(personal communication service，PCS)电话、无绳电话、会话发起协议(session initiation protocol，SIP)话机、无线本地环路(wireless local loop，WLL)站、个人数字助理(personal digital assistant，PDA)、等设备。还包括受限设备，例如功耗较低的设备，或存储能力有限的设备，或计算能力有限的设备等。例如包括条码、射频识别(radio frequency identification，RFID)、传感器、全球定位系统(global positioning system，GPS)、激光扫描器等信息传感设备。
二、RAN
RAN中可以包括一个或多个RAN设备，比如RAN设备1101、RAN设备1102。RAN 设备与终端设备之间的接口可以为Uu接口(或称为空口)。当然，在未来通信中，这些接口的名称可以不变，或者也可以用其它名称代替，本申请对此不限定。
RAN设备即为将终端设备接入到无线网络的节点或设备，RAN设备又可以称为网络设备或基站。RAN设备例如包括但不限于：5G通信系统中的新一代基站(generation Node B，gNB)、演进型节点B(evolved node B，eNB)、无线网络控制器(radio network controller，RNC)、节点B(node B，NB)、基站控制器(base station controller，BSC)、基站收发台(base transceiver station，BTS)、家庭基站(例如，home evolved nodeB，或home node B，HNB)、基带单元(baseBand unit，BBU)、传输接收点(transmitting and receiving point，TRP)、发射点(transmitting point，TP)、移动交换中心等。
(1)协议层结构
RAN设备和终端设备之间的通信遵循一定的协议层结构，例如控制面协议层结构可以包括RRC层、分组数据汇聚层协议(packet data convergence protocol，PDCP)层、无线链路控制(radio link control，RLC)层、媒体接入控制(media access control，MAC)层和物理层等协议层的功能；用户面协议层结构可以包括PDCP层、RLC层、MAC层和物理层等协议层的功能，在一种可能的实现中，PDCP层之上还可以包括业务数据适配(service data adaptation protocol，SDAP)层。
以网络设备和终端设备之间的数据传输为例，数据传输需要经过用户面协议层，比如经过SDAP层、PDCP层、RLC层、MAC层、物理层，其中，SDAP层、PDCP层、RLC层、MAC层、物理层也可以统称为接入层。根据数据的传输方向分为发送或接收，上述每层又分为发送部分和接收部分。以下数据传输为例，参见图2a所示为下行数据在各层间传输示意图，图2a中向下的箭头表示数据发送，向上的箭头表示数据接收。PDCP层自上层取得数据后，会将数据传送到RLC层与MAC层，再由MAC层生成传输块，然后通过物理层进行无线传输。数据在各个层中进行相对应的封装，某一层从该层的上层收到的数据视为该层的服务数据单元(service data unit，SDU)，经过层封装后成为PDU，再传递给下一个层。
示例性地，根据图2a还可以看出，终端设备还具有应用层和非接入层；其中，应用层可以用于向终端设备中所安装的应用程序提供服务，比如，终端设备接收到的下行数据可以由物理层依次传输到应用层，进而由应用层提供给应用程序；又比如，应用层可以获取应用程序产生的数据，并将数据依次传输到物理层，发送给其它通信装置。非接入层可以用于转发用户数据，比如将从应用层接收到的上行数据转发给SDAP层或者将从SDAP层接收到的下行数据转发给应用层。
(2)CU和DU
本申请实施例中，RAN设备可以包括集中式单元(centralized unit，CU)和分布式单元(distributed unit，DU)，多个DU可以由一个CU集中控制。作为示例，CU和DU之间的接口可以称为F1接口，其中，控制面(control panel，CP)接口可以为F1-C，用户面(user panel，UP)接口可以为F1-U。CU和DU可以根据无线网络的协议层划分：比如图2b所示，PDCP层及以上协议层的功能设置在CU，PDCP层以下协议层(例如RLC层和MAC层等)的功能设置在DU；又比如图2c所示，PDCP层以上协议层的功能设置在CU，PDCP层及以下协议层的功能设置在DU。
可以理解的，上述对CU和DU的处理功能按照协议层的划分仅仅是一种举例，也可 以按照其他的方式进行划分，例如可以将CU或者DU划分为具有更多协议层的功能，又例如CU或DU还可以划分为具有协议层的部分处理功能。在一种设计中，将RLC层的部分功能和RLC层以上的协议层的功能设置在CU，将RLC层的剩余功能和RLC层以下的协议层的功能设置在DU。在另一种设计中，还可以按照业务类型或者其他系统需求对CU或者DU的功能进行划分，例如按时延划分，将处理时间需要满足时延要求的功能设置在DU，不需要满足该时延要求的功能设置在CU。在另一种设计中，CU也可以具有核心网的一个或多个功能。示例性地，CU可以设置在网络侧方便集中管理；DU可以具有多个射频功能，也可以将射频功能拉远设置。本申请实施例对此并不进行限定。
示例性地，CU的功能可以由一个实体来实现，或者也可以由不同的实体来实现。例如，如图2d所示，可以对CU的功能进行进一步切分，即将控制面和用户面分离并通过不同实体来实现，分别为控制面CU实体(即CU-CP实体)和用户面CU实体(即CU-UP实体)。该CU-CP实体和CU-UP实体可以与DU相耦合，共同完成RAN设备的功能。
需要说明的是：在上述图2b至图2d所示意的架构中，CU产生的信令可以通过DU发送给终端设备，或者终端设备产生的信令可以通过DU发送给CU。DU可以不对该信令进行解析而直接通过协议层封装后透传给终端设备或CU。以下实施例中如果涉及这种信令在DU和终端设备之间的传输，此时，DU对信令的发送或接收包括这种场景。例如，RRC或PDCP层的信令最终会处理为物理层的信令发送给终端设备，或者，由接收到的物理层的信令转变而来。在这种架构下，该RRC或PDCP层的信令，即也可以认为是由DU发送的，或者，由DU和射频装载发送的。
三、CN
CN中可以包括一个或多个CN设备，比如CN设备120。以5G通信系统为例，CN中可以包括接入和移动性管理功能(access and mobility management function，AMF)网元、会话管理功能(session management function，SMF)网元、用户面功能(user plane function，UPF)网元、策略控制功能(policy control function，PCF)网元、统一数据管理(unified data management，UDM)网元、应用功能(application function，AF)网元等。
应理解，图1所示的通信系统中各个设备的数量仅作为示意，本申请实施例并不限于此，实际应用中在通信系统中还可以包括更多的终端设备、更多的RAN设备，还可以包括其它设备。
上述图1所示意的网络架构可以适用于各种无线接入技术(radio access technology，RAT)的通信系统中，例如可以是4G(或者称为长期演进(long term evolution，LTE))通信系统，也可以是5G(或者称为新无线(new radio，NR))通信系统，也可以是LTE通信系统与5G通信系统之间的过渡系统，该过渡系统也可以称为4.5G通信系统，当然也可以是未来的通信系统中。本申请实施例描述的网络架构以及业务场景是为了更加清楚的说明本申请实施例的技术方案，并不构成对于本申请实施例提供的技术方案的限定，本领域普通技术人员可知，随着通信网络架构的演变和新业务场景的出现，本申请实施例提供的技术方案对于类似的技术问题，同样适用。
在上述图1所示意的网络架构中，针对于CU和DU分离的场景，为了实现终端设备和无线网络侧进行高精度的时间同步，一种可能的实现方式为：CU从DU获取DU侧的参考时间，并将DU侧的参考时间发送给终端设备；相应地，终端设备可以根据DU侧 的参考时间以及终端设备和DU之间的单向传输时延，确定终端设备侧的参考时间，进而实现终端设备和无线网络侧进行高精度的时间同步。下面结合图3对终端设备和无线网络侧进行高精度的时间同步的过程进行详细描述。
图3为终端设备和无线网络侧进行高精度的时间同步的流程示意图，如图3所示，该流程可以包括：
步骤301，CU向DU发送参考时间信息报告控制(reference time information reporting control)消息，参考时间信息报告控制消息用于请求DU侧的参考时间。
步骤302，DU向CU发送参考时间信息报告(reference time information report)消息，参考时间信息报告消息用于指示DU侧的参考时间。
步骤303，CU向终端设备发送DU侧的参考时间。
步骤304，终端设备接收DU发送的定时提前命令(timing advance command，TAC)，并根据定时提前命令，确定终端设备的定时提前(timing advance，TA)值。
步骤305，终端设备根据TA值得到终端设备和DU之间的单向传输时延，进而根据DU侧的参考时间以及终端设备和DU之间的单向传输时延，确定终端设备侧的参考时间。
步骤306，终端设备根据终端设备侧的参考时间进行高精度的时间同步。
其中，DU侧的参考时间可以理解为DU在参考点的参考时间，终端设备侧的参考时间可以理解为终端设备在参考点的参考时间。本申请实施例中，参考点可以为协议预先规定的，或者，也可以是由DU或CU指示的，具体不做限定。在一个示例中，参考点可以为参考系统帧号(system frame number，SFN)所对应的无线帧的起始边界或结束边界。
采用该种方式，一方面，CU将DU侧的参考时间发送给终端设备，终端设备接收到DU侧的参考时间后，需要结合终端设备和DU之间的单向传输时延，来确定终端设备的参考时间，从而导致终端设备的处理复杂度较高。另一方面，终端设备是根据TA来确定终端设备和DU之间的单向传输时延(比如单向传输时延等于TA值的二分之一)，由于TA值的精度较低，从而可能导致终端设备确定的终端设备的参考时间无法满足高精度的时间同步的要求。
基于此，本申请实施例中将针对于CU和DU分离的场景中，终端设备和无线网络侧进行高精度的时间同步的相关实现进行研究。示例性地，本申请实施例提供一种时间同步方法，用于降低终端设备进行时间同步的复杂度。
需要说明的是，本申请实施例中的时间也可以理解为时钟(clock)，在本申请实施例中不区分时间和时钟的概念，即可以将时间和时钟看做是等同的概念。比如，终端设备进行时间同步，也可以理解为终端设备进行时钟同步。
下面先对本申请实施例所涉及的相关技术特征进行解释说明。需要说明的是，这些解释是为了让本申请实施例更容易被理解，而不应该视为对本申请所要求的保护范围的限定。
一、下行同步
在上述图1所示意的网络架构中，终端设备可以通过接收网络设备发送的同步信号和PBCH块(synchronization signal and PBCH block，SSB)来实现与网络设备的下行同步，比如帧同步，从而终端设备可以根据参考SFN获知参考SFN对应的无线帧，以便于在参考SFN对应的无线帧的起始边界或结束边界进行高精度的时间同步。其中，SSB包括主同 步信号(primary synchronisation signal，PSS)、辅同步信号(secondary synchronisation signal，SSS)和物理广播信道( physical broadcast channel，PBCH)。
二、上行同步
以终端设备1和终端设备2为例，如图4的(a)所示，由于网络设备(比如DU)和终端设备之间的信号传播有延迟，从网络设备发送下行信号的起始时刻到终端设备1接收下行信号的起始时刻的间隔为ΔT 1＝d 1/c，其中d 1为网络设备和终端设备1之间的距离，c为信号传播速度。对于无线通信，c为光速。类似地，ΔT 2＝d 2/c，其中d 2为网络设备和终端设备2之间的距离。如果终端设备1不进行上行定时调整，以接收下行信号的起始时刻为参考向网络设备发送上行信号，从终端设备1发送上行信号的起始时刻到网络设备接收上行信号的起始时刻的间隔同样为ΔT 1。因此，针对终端设备1，网络设备从发送下行信号的起始时刻到接收上行信号的起始时刻存在2ΔT 1的时间差，同理，针对终端设备2，网络设备从发送下行信号的起始时刻到接收上行信号的起始时刻存在2ΔT 2的时间差。
(1)单向传输时延、环回传输时延
图4的(a)中，网络设备发送下行信号的起始时刻到终端设备接收下行信号的起始时刻的间隔(比如ΔT 1或ΔT 2)即为网络设备和终端设备之间的下行传输时延，终端设备发送上行信号的起始时刻到网络设备接收上行信号的起始时刻的间隔(比如ΔT 1或ΔT 2)即为网络设备和终端设备之间的上行传输时延。其中，下行传输时延和上行传输时延之和即为环回传输时延。假设下行传输时延和上行传输时延相等，因此，也可以将下行传输时延或上行传输时延称为单向传输时延，环回传输时延等于单向传输时延的两倍。
示例性地，以环回传输时延为例，当采用不同的时间精度时，环回传输时延的具体取值也会不同。因此，表征环回传输时延的时间长度可能有多种，比如第一时间长度，又比如TA值。
(2)第一时间长度
网络设备确定第一时间长度的方式可以有多种，比如在随机接入过程中，网络设备可以根据终端设备发送的随机接入前导码，测量得到网络设备发送的同一时隙的下行信号的起始时刻到接收同一时隙的随机接入前导码的起始时刻的间隔为第一时间长度。又比如在非随机接入过程中(此时终端设备可以处于连接态)，网络设备可以根据终端设备发送的上行信号，测量得到网络设备发送下行信号的起始时刻到接收上行信号的起始时刻的间隔为第三时间长度(由于终端设备发送上行信号时进行了定时调整，因此，此处的第三时间长度可以理解为第一时间长度的调整量)，进而根据第三时间长度对之前测量得到的第一时间长度进行更新得到新的第一时间长度。示例性地，第一时间长度的时间精度可以为一纳秒或十纳秒。其中，若上行信号收到的起始时刻在下行信号的起始时刻之后，则说明终端设备的环回传输时延变长，则更新后的第一时间长度＝上一次测量得到的第一时间长度+第三时间长度。若上行信号的收到的起始时刻在下行信号的起始时刻之前，则说明终端设备的环回传输时延变短，更新后的第一时间长度＝上一次测量得到的第一时间长度—第三时间长度。
其中，非随机接入过程中的上行信号可以为探测参考信号(sounding reference signal，SRS)、或者解调参考信号(demodulation reference signal，DMRS)、或者信道质量指示(channel quality indicator，CQI)、或者确认回答(acknowledgement，ACK)、或者否定回答(negative acknowledgement，NACK)、或者物理上行共享信道(physical uplink shared  channel，PUSCH)。
(3)TA值
如图4的(a)所示，由于各个终端设备和网络设备之间的距离不同，使得上行信号到达网络设备的时间各不相同，造成终端设备之间可能存在定时偏差。而当定时偏差大于正交频分复用(orthogonal frequency division multiple，OFDM)符号的循环前缀(cyclic prefix，CP)时，终端设备之间会互相干扰。为了解决终端设备之间的干扰问题，终端设备需要进行定时调整，以实现上行同步。如图4的(b)所示，终端设备1将发送上行信号的起始时刻提前2ΔT 1，终端设备2将发送上行信号的起始时刻提前2ΔT 2，则网络设备将在相同的时刻接收到终端设备1和终端设备2的上行信号，从而解决终端设备间互相干扰的问题。
示例性地，网络设备可以确定TA值，并向终端设备发送定时提前命令，进而终端设备可以根据定时提前命令确定TA值；其中，网络设备和终端设备可以均维护该TA值。
在一种可能的场景(即随机接入过程)中，网络设备可以根据终端设备发送的随机接入前导码确定定时提前命令，并通过随机接入响应(random access response，RAR)向终端设备发送定时提前命令；相应地，终端设备可以根据定时提前命令得到TA值。其中，在5G通信系统中，定时提前命令可以包括12个比特(对应的取值范围为0～3846)。定时提前命令可以指示TA值的调整量(为便于描述，称为第一调整量)，进而终端设备可以根据第一调整量计算出TA值。
比如，第一调整量为N TA1，则终端设备可以如下公式确定TA值：
TA值＝N TA1*step+N TA,offset*Tc……公式1
其中，step为TA值调整的粒度/步长，step＝16*64Tc/2 μ，Tc为5G通信系统定义的最小时间单位，μ的取值和RAR后的上行传输消息(比如随机接入过程的第3消息)对应的子载波间隔(subcarrier space，SCS)有关，2 μ＝SCS/15kHz，若SCS＝15kHz，则2 μ＝1；若SCS＝30kHz，则2 μ＝2，依次类推。当随机接入过程中的第3消息对应的SCS等于15kHz时，step＝520.83ns。终端设备确定N TA,offset的具体实现可以参见现有方案，在一个示例中，N TA,offset可以等于0。
在又一种可能的场景(即非随机接入过程)中，网络设备可以向处于连接态的终端设备发送定时提前命令。示例性地，终端设备在随机接入过程中与网络设备取得上行同步后，可能会由于多种原因而导致定时提前量失效，因此，终端设备需要不断地更新定时提前量。其中，导致定时提前量失效的原因可以有多种，比如对于高速移动中的终端设备(例如运行中的高铁上的终端设备)来说，其与网络设备的传输延迟会不断变化，进而需要不断更新定时提前量。在该种场景中，网络设备根据终端设备发送的上行信号确定定时提前命令，并通过MAC控制元素(control element，CE)向终端设备发送定时提前命令。定时提前命令可以包括6个比特(对应的取值范围为0～63)，定时提前命令可以指示TA值的调整量(为便于描述，称为第二调整量)，进而终端设备可以根据第二调整量计算出TA值。
比如，第二调整量的取值为N TA2，则终端设备可以如下公式确定TA值(也可以称为TAnew)：
TA值＝TAold+(N TA2-31)*step……公式2
其中，TAnew为终端设备当前的上行定时提前，TAold为终端设备前次的上行定时提前。step为TA调整的粒度/步长，step＝16*64Tc/2 μ，μ为N TA2对应的TA组(TA group，TAG)内多个激活上行带宽部分(bandwidth part，BWP)中的最大SCS有关，2 μ＝SCS/15kHz， 当TAG内激活的上行BWP中最大SCS为15kHz，则step＝520.83ns。
(4)第一时间长度和TA值的关系
第一时间长度和TA值均可以表征终端设备与网络设备之间的环回传输时延；其中，从网络设备的角度来看，TA值可以是根据第一时间长度得到的。
比如，在随机接入过程中，网络设备可以根据终端设备发送的随机接入前导码测量得到第一时间长度，进而根据第一时间长度确定TA值(或者定时提前命令)。网络设备根据终端设备发送的随机接入前导码测量得到第一时间长度的时间精度可以为一纳秒或十纳秒，即网络设备确定的第一时间长度为一个时间精度较高的值，但由于定时提前命令包括12个比特(TA值调整的步长较大)，因此，终端设备的TA值为一个时间精度较小(小于第一时间长度的时间精度)的值。举个例子，以step＝520.83ns，N TA,offset＝0为例，若网络设备根据终端设备发送的随机接入前导码测量得到第一时间长度为1100ns，则根据第一时间长度可以确定N TA1＝2，TA值＝520.83*2＝1041.66ns。可以看出，由于第一时间长度的时间精度和TA值的时间精度不同，从而导致第一时间长度和TA值在数值上存在差异。
又比如，在非随机接入过程中，网络设备根据终端设备发送的上行信号测量得到第一时间长度的调整量(由于在非随机接入过程中，终端设备是根据TAold发送的上行信号，此种情形下，网络设备可以根据上行信号测量得到第一时间长度的调整量)后，可以根据第一时间长度的调整量更新第一时间长度得到新的第一时间长度，以及根据新的第一时间长度确定TAnew，进而根据TAnew和TAold确定定时提前命令(N TA2)。或者，网络设备也可以根据第一时间长度的调整量直接确定定时提前命令(N TA2)，进一步地，网络设备还可以根据N TA2和TAold确定TAnew。
需要说明的是：(1)上述内容是以终端设备和网络设备之间交互为例进行描述，同样也适用于CU和DU分离的场景。比如在CU和DU分离的场景中，可以由DU根据上述所描述的方式来确定第一时间长度和/或TA值。
(2)本申请实施例中，时间精度的取值可以包括两部分内容，第一部分为数值，第二部分为时间单位。比如，以TA值为例，则TA值的时间精度的第二部分取决于TA值的最小时间单位(比如ns)，第一部分取决于TA值调整的粒度(或步长)(比如520.83)，进而可知TA值的时间精度的取值为520.83ns。又比如，以第一时间长度为例，则第一时间长度的时间精度的第二部分取决于第一时间长度的最小时间单位，第一部分取决于第一时间长度调整的粒度。示例性地，时间精度的取值越小，则说明时间精度越高；取值越大，则说明时间精度越低。
基于上述相关技术特征，下面结合实施例一至实施例三，对本申请实施例提供的时间同步方法进行详细描述。
在一个示例中，本申请实施例提供的时间同步方法可以包括：CU确定第一参考时间，第一参考时间为终端设备在参考点的参考时间，CU向终端设备发送第一信息，第一信息用于指示第一参考时间；终端设备接收到第一信息后，可以获取到终端设备在参考点的参考时间。采用该种方式，终端设备可以从CU获取到终端设备在参考点的参考时间，相比于终端设备根据从CU获取DU侧的参考时间以及终端设备和DU之间的单向传输时延来确定终端设备在参考点的参考时间的方案来说，能够有效降低终端设备的处理复杂度，节省终端设备的功耗。此外，由于CU可以通过高层信令(比如RRC消息)向终端设备发送第一信息，从而能够有效保证信息传输的安全性。
示例性地，上述方法可以包括两种可能的方案，分别为方案一和方案二。在方案一中，CU可以接收来自DU的第二信息和第三信息；其中，第二信息用于指示第二参考时间，第二参考时间为DU在参考点的参考时间，第三信息用于确定DU和终端设备之间的单向传输时延；以及，CU可以根据第二参考时间和单向传输时延确定第一参考时间，并向终端设备发送第一信息，第一信息用于指示第一参考时间。采用该种方式，由CU根据DU发送的第二信息和第三信息确定第一参考时间并发送给终端设备，相比于终端设备根据从CU获取DU侧的参考时间以及终端设备和DU之间的单向传输时延来确定终端设备在参考点的参考时间的方案来说，由于CU相比于终端设备来说具有更强的处理能力，从而能够保证确定的第一参考时间较为准确。
在方案二中，DU可以根据第二参考时间和单向传输时延确定第一参考时间，并向CU发送第一参考时间，进而由CU向终端设备发送第一信息，第一信息用于指示第一参考时间。采用该种方式，由DU确定第一参考时间并发送给CU，进而由CU发送给终端设备，而不需要DU将第二参考时间和单向传输时延发送给CU，再由CU计算第一参考时间，从而降低了CU和DU之间的信令开销。
在又一个示例中，本申请实施例提供的时间同步方法可以包括(为便于描述，称为方案三)：DU可以根据第二参考时间和单向传输时延确定第一参考时间，并将第一参考时间发送给终端设备。采用该种方式，由DU确定第一参考时间并发送给终端设备，从而能够有效提高传输效率，降低CU和DU之间的信令开销。
需要说明的是：终端设备在参考点的参考时间，也可以替换为终端设备侧的参考时间；终端设备侧的参考时间是指经过空口传输时延补偿的时间。DU在参考点的参考时间，也可以替换为：DU侧的参考时间，或者网络侧在参考点的参考时间，或者网络侧的参考时间。
实施例一
在实施例一中，将基于方案一描述时间同步方法的一种可能的实现。
图5为本申请实施例一提供的时间同步方法所对应的流程示意图。如图5所示，包括：
步骤501，CU向DU发送第一请求信息，相应地，DU接收第一请求信息。
此处，CU向DU发送第一请求信息的触发因素可能有多种。比如，终端设备确定需要进行高精度的时间同步后，向CU发送时间同步请求；相应地，CU接收到终端设备发送的时间同步请求后，可以向DU发送第一请求信息。又比如，CU确定终端设备需要进行高精度的时间同步后，可以向DU发送第一请求信息。
步骤502，DU根据第一请求信息向CU发送第二信息和第三信息；其中，第二信息用于指示第二参考时间，第二参考时间为DU在参考点的参考时间，第三信息用于确定DU和终端设备之间的单向传输时延。相应地，CU接收第二信息和第三信息。
此处，DU向CU发送第二信息和第三信息的方式可以有多种。在一种可能的实现方式中，DU可以通过同一消息向CU发送第二信息和第三信息，比如DU可以通过如下任一消息向CU发送第二信息和第三信息：参考时间信息报告消息、初始上行RRC传输(initial uplink RRC message transfer)消息、上行RRC传输(uplink RRC message transfer)消息、终端设备的上下文建立响应(UE context setup response)消息、终端设备的上下文修改响应(UE context modify response)消息。在又一种可能的实现方式中，DU可以通过不同消息向CU发送第二信息和第三信息，比如，DU可以通过参考时间信息报告消息向CU发送 第二信息，以及通过上行RRC传输消息向终端设备发送第三信息。
下面分别对上述所涉及的第一请求信息、第二信息和第三信息等进行详细说明。
一、第一请求信息
第一请求信息可以承载于参考时间信息报告控制消息、或者下行RRC传输(downlink RRC message transfer)消息、或者终端设备的上下文建立请求(UE context setup request)消息、或者终端设备的上下文修改请求(UE context modify request)消息。
下面描述两种可能的实现方式。
实现方式1，第一请求信息可以用于请求第二信息和第三信息，或者说，第一请求信息可以用于请求第二参考时间和单向传输时延。比如第一请求信息可以包括指示DU上报第二信息和第三信息的信息(或者说，指示DU上报第二参考时间和单向传输时延的信息)，进一步地，第一请求信息还可以包括终端设备的标识。此处，指示DU上报第二信息和第三信息的信息可以包括指示DU上报第二信息的信息(为便于描述，称为信息1)和指示DU上报第三信息的信息(称为信息2)，信息1和信息2可以是同一信息(比如承载于同一信元的信息)，或者也可以是不同的信息(比如分别承载于不同的信元的信息)。又比如第一请求信息可以包括终端设备的标识，此种情形下，可以通过终端设备的标识来隐式指示DU上报第二信息和第三信息。以第一请求信息承载于参考时间信息报告控制消息为例，则DU接收到参考时间信息报告控制消息后，若确定参考时间信息报告控制消息中包括第一请求信息，则可以向CU发送第二信息和第三信息，比如，DU可以通过参考时间信息报告消息向CU发送第二信息和第三信息；若确定参考时间信息报告控制消息中不包括第一请求信息，则可以向CU发送第二信息，而不再发送第三信息，后续实现可以参见上述图3的描述。
示例性地，DU确定参考时间信息报告控制消息中包括第一请求信息后，可以获取DU的能力信息，并根据DU的能力信息判断DU是否支持上报单向传输时延。若确定DU支持上报单向传输时延，则可以向CU发送第二信息和第三信息；若确定DU不支持上报单向传输时延，则可以向CU发送第二信息，而不再发送第三信息，后续实现可以参见上述图3的描述。
实现方式2，第一请求信息可以用于请求第三信息(即DU和终端设备之间的单向传输时延)，第一请求信息可以包括指示DU上报第三信息的信息，进一步地，第一请求信息还可以包括终端设备的标识。又比如第一请求信息可以包括终端设备的标识，此种情形下，可以通过终端设备的标识来隐式指示DU上报第三信息。
以第一请求信息承载于参考时间信息报告控制消息为例，此种情形下，DU接收到参考时间信息报告控制消息后，若确定参考时间信息报告控制消息中包括第一请求信息，则可以向CU发送第二信息和第三信息；若确定参考时间信息报告控制消息中不包括第一请求信息，则可以向CU发送第二信息，而不再发送第三信息，后续实现可以参见上述图3的描述。
以第一请求信息承载于参考时间信息报告控制消息以外的其它消息(如下行RRC传输消息)为例，此种情形下，DU可以在接收到下行RRC传输消息后，若确定下行RRC传输消息包括第一请求信息，则可以向CU发送第三信息，比如DU可以通过上行RRC传输消息向CU发送第三信息；以及在接收到参考时间信息报告控制消息，向CU发送第二信息，比如DU可以通过参考时间信息报告消息向CU发送第二信息。
在该种实现方式中，DU可以向CU发送DU的能力信息，DU的能力信息用于指示DU是否支持上报单向传输时延。相应地，CU接收到DU上报的能力信息后，若确定DU支持上报单向传输时延，则可以向DU发送第一请求信息，若确定DU不支持上报单向传输时延，则可以不再向DU发送第一请求信息，以节省资源开销。其中，DU可以向CU发送DU的能力信息的方式可以有多种，比如DU可以主动向CU上报能力信息，或者DU也可以基于CU的指示向CU上报能力信息。在一个示例中，DU可以通过F1建立响应消息或DU配置更新消息向CU发送能力信息。
需要说明的是：(1)上述是以第一请求信息包括一个终端设备的标识为例进行描述的，在其它可能的示例中，第一请求信息可以包括多个终端设备的标识，相应地，DU接收到第一请求信息后，可以向CU发送多个第三信息，多个第三信息分别用于确定DU与多个终端设备之间的单向传输时延。在一个示例中，多个第三信息可以承载于同一消息，即DU可以一次性向CU发送多个第三信息。(2)本申请实施例中，终端设备的标识可以为gNB-DU UE F1应用协议(F1 application protocol，F1AP)标识(ID)，或者终端设备的标识可以包括gNB-DU UE F1AP ID和gNB-CU UE F1AP ID。其中，gNB-DU UE F1AP ID可以为DU为终端设备分配的F1AP ID，gNB-CU UE F1AP ID可以为CU终端设备分配的F1AP ID。在其它可能的示例中，终端设备的标识也可以为其它用于标识终端设备的信息，比如，终端设备的标识可以为小区标识与小区无线网络临时标识(cell radio network temporary identifier，C-RNTI)的组合；又比如，若终端设备处于非激活态(INACTIVE)态，则终端设备的标识可以为非激活态无线网络临时标识(Inactive-radio network temporary identifier，I-RNTI)，其中，I-RNTI用于在一个无线通知网络区域内区分不同终端设备。
二、第二信息
如上所述，第二信息用于指示第二参考时间(即DU在参考点的参考时间)。第二参考时间的时间单位可以为毫秒、微妙、飞秒、纳秒或其他更小量级的时间单位，本申请实施例对第二参考时间的时间单位并不进行限定，在此仅是示例性说明。
第二信息可以包括相对于预设时间的第一数值，可选地，还可以包括参考点信息、时间类型信息和不确定的误差值中的至少一项。下面分别进行详细说明。
(1)第一数值
第一数值可以包括第二参考时间对应的多个时间参数，多个时间参数可以对应不同的时间精度。示例性地，多个时间参数可以包括相对于预设时间的天数值(比如a)、秒数值(比如b)、毫秒数值(比如c)、十纳秒为单位的数值(比如d)。则第二参考时间为：a*86400*1000*100000+b*1000*100000+c*100000+d。
(2)时间类型信息
时间类型信息用于指示第二参考时间的时间类型，其中，第二参考时间的时间类型可以包括GPS时间、协调世界时(coordinated universal time，UTC)时间或本地时间。①比如，第二参考时间的时间类型为GPS时间，则第二参考时间可以为DU从时钟源获取的、相对GPS起始时间(即预设时间)的时间。其中，GPS起始时间可以为：阳历1980年1月6日00:00:00。②又比如，第二参考时间的时间类型为本地时间，则第二参考时间可以为DU从时钟源获取的、相对本地起始时间(即预设时间)的时间。其中，本地起始时间可以根据同步时钟源的本地时钟来决定。③又比如，第二参考时间的时间类型为UTC时间，则第二参考时间可以为DU从时钟源获取的GPS时间减去闰秒(leap Seconds)得到 的、相对UTC起始时间(即预设时间)的时间。其中，UTC起始时间可以为：阳历1900年1月1日00:00:00(在1899年12月31日周日和1900年1月1日周一间的午夜)。
需要说明的是，本申请实施例对于DU获取第二参考时间的具体方式不做限定，上述仅是示例性说明。
(3)参考点信息
参考点信息用于指示参考点，参考点可以为无线帧的起始边界或结束边界。比如，参考点信息包括参考SFN，此种情形下，参考点可以为参考SFN对应的无线帧的起始边界或结束边界。
需要说明的是，上述对第二信息可能包括的一些信息进行了描述，在其它可能的示例中，第二信息还可以包括其它信息，具体不做限定。
三、第三信息
如上所述，第三信息用于确定DU和终端设备之间的单向传输时延。示例性地，第三信息可以包括如下至少一项：第一时间长度、第二时间长度、TA值、TA值的一半、TA值的调整量。可选地，第三信息还可以包括终端设备的标识。
(1)第一时间长度、第二时间长度
第一时间长度可以参见前文的描述。第二时间长度可以为第一时间长度的一半，因此第二时间长度可以表征单向传输时延。示例性地，DU确定出第一时间长度后，可以计算得到第二时间长度。第一时间长度或第二时间长度的时间精度高于TA值的时间精度，比如，第一时间长度或第二时间长度的时间精度可以为一纳秒或十纳秒。
若第三信息包括第一时间长度，则CU可以将第一时间长度的一半作为单向传输时延。若第三信息包括第二时间长度，则CU可以直接将第二时间长度作为单向传输时延。
(2)TA值、TA值的一半
TA值可以是根据第一时间长度得到的。TA值可以表征环回传输时延，TA值的一半可表征单向传输时延。比如，在随机接入过程或非随机接入过程中，网络设备确定出第一时间长度，可以根据第一时间长度计算得到TA值。
若第三信息包括TA值，则CU可以将TA值的一半作为单向传输时延。若第三信息包括TA值的一半，则CU可以直接将TA值的一半作为单向传输时延。
(3)TA值的调整量
参见前文的描述可知，TA值的调整量可以为第一调整量或第二调整量。若第三信息包括第一调整量，则CU可以根据第一调整量确定TA值(参见公式1)，进而将TA值的一半作为单向传输时延。若第三信息包括第二调整量，则CU可以根据原TA值(即TAold)和第二调整量确定TA值(参见公式2)，进而将TA值的一半作为单向传输时延。
在一个示例中，当第三信息包括TA值的调整量时，第三信息还可以包括指示信息1，指示信息1用于指示TA值的调整量为第一调整量或第二调整量。比如，指示信息1包括1个比特，当该比特的取值为1时，指示TA值的调整量为第一调整量；当该比特的取值为0时，指示TA值的调整量为第二调整量。在又一个示例中，可以预先设置两个信元，分别为信元1和信元2，信元1用于承载第一调整量，信元2用于承载第二调整量。此种情形下，CU可以通过不同信元来确定TA值的调整量为第一调整量或第二调整量。
本申请实施例中，用于承载第一调整量的信元(比如信元1)所包括的比特数目可以大于或等于12，用于承载第二调整量的信元(比如信元2)所包括的比特数目可以大于或 等于6。以第一调整量为例，对于相同的第一调整量，当用于承载第一调整量的信元所包括的比特数目越大时，step相应越小，精度越高，比如，用于承载第一调整量的信元所包括的比特数目为12时，则step＝16*64Tc/2 μ，用于承载第一调整量的信元所包括的比特数目为16时，则step＝64Tc/2 μ，用于承载第一调整量的信元所包括的比特数目为16时的step为用于承载第一调整量的信元所包括的比特数目为12时的step的十六分之一，从而可以提高第一调整量的时间精度。由于TA值是根据第一调整量确定的(参见前文的公式1)，从而使得TA值的时间精度也较高，相应地，在下文的步骤503中，CU根据第二参考时间和TA值的一半(单向传输时延)确定的第一参考时间也更能符合高精度的时间同步的需求。
此外，DU发送给终端设备的定时提前命令(指示第一调整量)也可以大于12个比特，从而使得终端设备根据第一调整量确定的TA值的时间精度较高。DU发送给终端设备的定时提前命令(指示第二调整量)也可以大于6个比特，从而使得终端设备根据第二调整量确定的TA值的时间精度较高。
需要说明的是，上述步骤501为可选步骤；比如DU若确定终端设备需要进行高精度的时间同步，则可以向CU发送第二信息和第三信息，此种情形下可以不再执行步骤501。
步骤503，CU根据第二参考时间和单向传输时延确定第一参考时间。
比如，CU可以在第二参考时间的基础上，加上单向传输时延，进而得到第一参考时间。
步骤504，CU向终端设备发送第一信息，第一信息用于指示第一参考时间。
此处，第一参考时间的时间单位可以为毫秒、微妙、飞秒、纳秒或其他更小量级的时间单位，本申请实施例对第一参考时间的时间单位并不进行限定，在此仅是示例性说明。
示例性地，第一信息指示第一参考时间的实现可以参照第二信息指示第二参考时间的实现。比如，第一信息可以包括第一参考时间对应的多个时间参数，可选地，还可以包括参考点信息、时间类型信息(用于指示第一参考时间的时间类型)和不确定的误差值中的至少一项。其中，第一信息中所包括的参考点信息和第二信息中所包括的参考点信息可以相同，第一参考时间的时间类型和第二参考时间的时间类型可以相同，第一信息中所包括的不确定的误差值和第二信息中所包括的不确定的误差值可以相同。
本申请实施例中，第一信息还可以包括指示信息2，指示信息2用于指示第一信息所指示的参考时间为终端设备在参考点的参考时间(或者说终端侧的参考时间)。示例性地，指示信息2可以为一个布尔值，比如当取值为真(true)时，表示第一信息所指示的参考时间为终端设备在参考点的参考时间；当取值为伪(false)时，表示第一信息所指示的参考时间为DU在参考点的参考时间。
CU向终端设备发送第一信息的方式可以有多种，比如CU可以通过RRC消息向终端设备发送第一信息，其中，RRC消息可以为RRC重配置消息、切换命令、RRC连接恢复(RRC connection resume)消息、RRC连接建立消息或RRC连接重建立消息。
步骤505，终端设备接收第一信息，并根据第一参考时间进行时间同步。
示例性的，当CU通过RRC消息向终端设备发送第一信息，相应地，终端设备的RRC层可以接收第一信息，并根据指示信息2确定第一信息所指示的参考时间为终端设备在参考点的参考时间。进一步地，终端设备的RRC层可以根据第一参考时间和预设时间确定绝对时间，并可以向上层(比如非接入层和应用层)通知该绝对时间；相应地，终端设备 的应用层接收绝对时间后，可以根据该绝对时间实现终端设备侧与网络侧的时间同步。
其中，终端设备若确定第一参考时间的时间类型为GPS时间，则可以根据第一参考时间和GPS起始时间确定绝对时间。又比如，终端设备若确定第一参考时间的时间类型为本地时间，则可以根据第一参考时间和本地起始时间确定绝对时间。需要说明的是，若第一信息包括不确定的误差值，则终端设备可以根据第一参考时间、预设时间和不确定的误差值来确定绝对时间。
采用上述方法，DU可以向CU发送第二信息和第三信息，进而CU可以根据第二信息和第三信息确定终端设备在参考点的参考时间，并将终端设备在参考点的参考时间发送给终端设备，从而能够有效降低终端设备进行时间同步的处理复杂度，节省终端设备的功耗。此外，一方面，当第三信息可以包括第一时间长度或第二时间长度时，由于第一时间长度或第二时间长度的时间精度高于TA值的时间精度，从而使得CU确定出的终端设备在参考点的参考时间更能符合高精度时间同步的需求；或者，当第三信息包括TA值的调整量时，由于承载TA值的调整量的信元所包括的比特数目可以大于12(或大于6)，从而提高了TA值的调整量的时间精度，使得CU确定出的终端设备在参考点的参考时间更能符合高精度时间同步的需求。另一方面，由于CU可以通过高层信令(比如RRC消息)向终端设备发送终端设备在参考点的参考时间，从而能够有效保证信息传输的安全性。
实施例二
在实施例二中，将基于方案二描述时间同步方法的一种可能的实现。
图6为本申请实施例二提供的时间同步方法所对应的流程示意图。如图6所示，包括：
步骤601，CU向DU发送第二请求信息，第二请求信息可以用于请求终端设备在参考点的参考时间，或者说第二请求信息用于请求DU上报终端设备在参考点的参考时间；相应地，DU接收第二请求信息。
示例性地，第二请求信息可以承载于参考时间信息报告控制消息、或者下行RRC传输消息、或者终端设备的上下文建立请求消息、或者终端设备的上下文修改请求消息。
在一种可能的实现方式中，第二请求信息可以包括指示DU上报终端设备在参考点的参考时间的信息(为便于描述，称为指示信息3)，进一步地，第二请求信息还可以包括终端设备的标识。
比如(1)，指示信息3可以为一个布尔值，当取值为true时，指示DU上报终端设备在参考点的参考时间；当取值为false时，指示DU上报DU在参考点的参考时间。进一步地，当指示信息3的取值为true时，第二请求信息还可以包括终端设备的标识，当指示信息3的取值为false时，第二请求信息可以不再包括终端设备的标识。以第二请求信息承载于参考时间信息报告控制消息为例，DU接收到参考时间信息报告控制消息，若确定参考时间信息报告控制消息包括指示信息3(指示信息3的取值为true)和终端设备的标识，则可以获知CU请求的是终端设备在参考点的参考时间，若参考时间信息报告控制消息包括指示信息3(指示信息3的取值为false)，则可以获知CU请求的是DU在参考点的参考时间。
比如(2)，指示信息3可以包括一个比特，当该比特的取值为1时，指示DU上报终端设备在参考点的参考时间；当该比特的取值为0时，指示DU上报DU在参考点的参考时间。进一步地，当指示信息3的取值为1时，第二请求信息还可以包括终端设备的标识， 当指示信息3的取值为0时，第二请求信息可以不再包括终端设备的标识。以第二请求信息承载于参考时间信息报告控制消息为例，DU接收到参考时间信息报告控制消息，若确定参考时间信息报告控制消息包括指示信息3(指示信息3的取值为1)和终端设备的标识，则可以获知CU请求的是终端设备在参考点的参考时间，若参考时间信息报告控制消息包括指示信息3(指示信息3的取值为0)，则可以获知CU请求的是DU在参考点的参考时间。
比如(3)，当第二请求信息包括指示信息3时，指示DU上报终端设备在参考点的参考时间；当第二请求信息不包括指示信息3时，指示DU上报DU在参考点的参考时间。进一步地，当第二请求信息包括指示信息3时，第二请求信息还可以包括终端设备的标识；当第二请求信息不包括指示信息3时，第二请求信息可以不再包括终端设备的标识。以第二请求信息承载于参考时间信息报告控制消息为例，DU接收到参考时间信息报告控制消息，若确定参考时间信息报告控制消息包括指示信息3和终端设备的标识，则可以获知CU请求的是终端设备在参考点的参考时间，若确定参考时间信息报告控制消息不包括指示信息3和终端设备的标识，则可以获知CU请求的是DU在参考点的参考时间。
在又一种可能的实现方式中，第二请求信息包括终端设备的标识，此种情形下，可以通过终端设备的标识来隐式指示DU上报终端设备在参考点的参考时间。
比如，以第二请求信息承载于参考时间信息报告控制消息为例，DU接收到参考时间信息报告控制消息，若确定参考时间信息报告控制消息包括终端设备的标识，则可以获知CU请求的是终端设备在参考点的参考时间，若确定参考时间信息报告控制消息不包括终端设备的标识，则可以获知CU请求的是DU在参考点的参考时间。
步骤602，DU确定第一参考时间，第一参考时间为终端设备在参考点的参考时间。
此处，DU可以获取DU在参考点的参考时间以及DU和终端设备之间的单向传输时延，进而根据DU在参考点的参考时间以及单向传输时延，确定终端设备在参考点的参考时间。
其中，(1)DU获取DU在参考点的参考时间的实现可以参见实施例一中的描述，比如，DU可以从时钟源获取相对GPS起始时间的时间作为DU在参考点的参考时间；又比如，DU可以从时钟源获取的相对本地起始时间的时间作为DU在参考点的参考时间。
(2)DU获取DU和终端设备之间的单向传输时延的方式可以有多种，比如DU可以获取第一时间长度，并将第一时间长度的一半作为DU和终端设备之间的单向传输时延；又比如DU可以获取TA值，并将TA值的一半作为DU和终端设备之间的单向传输时延。其中，DU获取第一时间长度或TA值的方式可以参见前文中的描述。
需要说明的是，上述步骤601为可选步骤；比如DU若确定终端设备需要进行高精度的时间同步，则可以确定终端设备在参考点的参考时间，此种情形下可以不再执行步骤601。
步骤603，DU向CU发送第四信息，第四信息用于指示终端设备在参考点的参考时间(可以称为第一参考时间)；相应地，CU接收第四信息。
示例性地，第四信息可以承载于如下任一消息：参考时间信息报告消息、初始上行RRC传输消息、上行RRC传输消息、终端设备的上下文建立响应消息、或者终端设备的上下文修改响应消息。
示例性地，第四信息可以包括第一参考时间对应的多个时间参数；进一步地，第四信息还可以包括终端设备的标识。在一个示例中，第四信息还可以包括以下至少一项：时间 类型信息(用于指示第一参考时间的时间类型)、参考点信息、不确定的误差值。
步骤604，CU向终端设备发送第一信息。
此处，第一信息可以包括第一参考时间对应的多个时间参数，可选地，还可以包括参考点信息、时间类型信息(用于指示第一参考时间的时间类型)和不确定的误差值中的至少一项。其中，第一信息所包括的第一参考时间对应的多个时间参数、参考点信息、时间类型信息、不确定的误差值可以分别与第四信息所包括的第一参考时间对应的多个时间参数、参考点信息、时间类型信息、不确定的误差值相同。
示例性地，步骤604的具体实现可以参见实施例一中步骤504的相关描述，不再赘述。
步骤605，终端设备接收第一信息，并根据第一参考时间进行时间同步。
示例性地，步骤605的具体实现可以参见实施例一中步骤504的相关描述，不再赘述。
采用上述方法，DU可以确定终端设备在参考点的参考时间，并将终端设备在参考点的参考时间发送给CU，进而由CU发送给终端设备，能够有效降低终端设备进行时间同步的处理复杂度，节省终端设备的功耗；此外，一方面，通过DU来确定第一参考时间能够有效降低CU的处理负担；另一方面，DU可以通过第一时间长度来确定单向传输时延进而确定终端设备在参考点的参考时间，由于第一时间长度的时间精度较高，从而使得确定出的终端设备在参考点的参考时间更能符合高精度时间同步的需求。
实施例三
在实施例三中，将基于方案三描述时间同步方法的一种可能的实现。
图7为本申请实施例三提供的时间同步方法所对应的流程示意图。如图7所示，包括：
步骤701，CU向DU发送第三请求信息，相应地，DU接收第三请求信息。
此处，第三请求信息可以包括终端设备的标识，第三请求信息用于请求DU向终端设备发送终端设备在参考点的参考时间(即第一参考时间)。具体实现可以参见上文实施例二中的有关第二请求信息的描述。
步骤702，DU确定第一参考时间，第一参考时间为终端设备在参考点的参考时间。具体实现可以参见上文实施例二中的步骤602中的描述。
步骤703，DU向终端设备发送第五信息，第五信息用于指示第一参考时间。
示例性地，DU可以通过MAC CE或DCI向终端设备发送第五信息。
此处，第五信息所包括的内容可以和上述实施例一中所描述的第一信息所包括的内容相同，具体不再赘述。
步骤704，终端设备接收第五信息，并根据第一参考时间进行时间同步。
采用上述方法，由DU确定第一参考时间并发送给终端设备，从而能够有效提高传输效率，降低CU和DU之间的信令开销。
针对于上述实施例一至实施例三，需要说明的是：
(1)上文中侧重描述了实施例一至实施例三的区别之处，除区别之处的其它内容，实施例一至实施例三可以相互参照。
(2)实施例一至实施例三所描述的各个流程图的步骤编号仅为执行流程的一种示例，并不构成对步骤执行的先后顺序的限制，本申请实施例中相互之间没有时序依赖关系的步骤之间没有严格的执行顺序。此外，各个流程图中所示意的步骤并非全部是必须执行的步 骤，可以根据实际需要在各个流程图的基础上增添或者删除部分步骤，比如上述步骤501、步骤601、步骤701均可以选择性执行。
上述主要从设备交互的角度对本申请实施例提供的方案进行了介绍。可以理解的是，为了实现上述功能，CU或DU可以包括执行各个功能相应的硬件结构和/或软件模块。本领域技术人员应该很容易意识到，结合本文中所公开的实施例描述的各示例的单元及算法步骤，本申请的实施例能够以硬件或硬件和计算机软件的结合形式来实现。某个功能究竟以硬件还是计算机软件驱动硬件的方式来执行，取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本申请的范围。
本申请实施例可以根据上述方法示例对CU或DU进行功能单元的划分，例如，可以对应各个功能划分各个功能单元，也可以将两个或两个以上的功能集成在一个单元中。上述集成的单元既可以采用硬件的形式实现，也可以采用软件功能单元的形式实现。
在采用集成的单元的情况下，图8示出了本申请实施例中所涉及的装置的可能的示例性框图。如图8所示，装置800可以包括：处理单元802和通信单元803。处理单元802用于对装置800的动作进行控制管理。通信单元803用于支持装置800与其他设备的通信。可选地，通信单元803也称为收发单元，可以包括接收单元和/或发送单元，分别用于执行接收和发送操作。可选地，装置800还可以包括存储单元801，用于存储装置800的程序代码和/或数据。
该装置800可以为上述任一实施例中的CU、或者还可以为设置在CU中的芯片。处理单元802可以支持装置800执行上文中各方法示例中CU的动作。或者，处理单元802主要执行方法示例中的CU的内部动作，通信单元803可以支持装置800与其它设备(比如DU)之间的通信。
具体地，在一个实施例中：处理单元802用于，确定第一参考时间，第一参考时间为终端设备在参考点的参考时间；通信单元803用于，向终端设备发送第一信息，第一信息用于指示第一参考时间。
在一种可能的设计中，通信单元803还用于，接收来自DU的第二信息和第三信息；其中，第二信息用于指示第二参考时间，第二参考时间为DU在所述参考点的参考时间，第三信息用于确定DU和终端设备之间的单向传输时延；处理单元802具体用于，根据第二参考时间和所述单向传输时延确定第一参考时间。
在一种可能的设计中，通信单元803具体用于，向DU发送第一请求信息，第一请求信息用于请求所述单向传输时延，第一请求信息包括所述终端设备的标识；以及，接收DU根据第一请求信息发送的第三信息。
在一种可能的设计中，通信单元803还用于，接收来自DU的能力信息，所述能力信息用于指示所述DU支持上报所述单向传输时延。
在一种可能的设计中，第三信息包括以下至少一项：(1)第一时间长度，第一时间长度表征所述DU和所述终端设备之间的环回传输时延；第一时间长度是通过测量所述终端设备发送的第一上行信号或第二上行信号得到的；第一上行信号为随机接入前导码，第二上行信号不同于第一上行信号；(2)第二时间长度，第二时间长度为第一时间长度的一半；(3)所述终端设备的TA值；(4)所述TA值的一半；(5)所述TA值对应的调整量；其 中，第一时间长度或第二时间长度的时间精度高于所述TA值的时间精度。
在一种可能的设计中，通信单元803还用于，接收来自DU的第四信息，第四信息用于指示第一参考时间。
在一种可能的设计中，通信单元803具体用于，向DU发送第二请求信息，第二请求信息用于请求第一参考时间，第二请求信息包括终端设备的标识；以及，接收DU发送的第四信息。
该装置800可以为上述任一实施例中的DU、或者还可以为设置在DU中的芯片。处理单元802可以支持装置800执行上文中各方法示例中DU的动作。或者，处理单元802主要执行方法示例中的DU的内部动作，通信单元803可以支持装置800与其它设备(比如CU)之间的通信。
具体地，在一个实施例中：处理单元802用于，确定第二信息和第三信息；其中，第二信息用于指示第二参考时间，第二参考时间为所述DU在所述参考点的参考时间，第三信息用于确定所述DU和终端设备之间的单向传输时延；通信单元803用于，向CU发送第二信息和第三信息。
在一种可能的设计中，通信单元803具体用于，接收来自CU的第一请求信息，第一请求信息用于请求所述DU上报所述单向传输时延，第一请求信息包括所述终端设备的标识；以及，根据第一请求信息向所述CU发送第三信息。
在一种可能的设计中，通信单元803还用于，向所述CU发送所述DU的能力信息，所述能力信息用于指示所述DU支持上报所述单向传输时延。
在一种可能的设计中，通信单元803具体用于，接收来自CU的第一请求信息，第一请求信息用于请求第二信息和第三信息，第一请求信息包括终端设备的标识；以及，在处理单元802确定支持上报所述单向传输时延后，向所述CU发送第二信息和第三信息。
在一种可能的设计中，第三信息包括以下至少一项：(1)第一时间长度，第一时间长度表征所述DU和所述终端设备之间的环回传输时延；第一时间长度是通过测量所述终端设备发送的第一上行信号或第二上行信号得到的；第一上行信号为随机接入前导码，第二上行信号不同于第一上行信号；(2)第二时间长度，第二时间长度为第一时间长度的一半；(3)所述终端设备的定时提前TA值；(4)所述TA值的一半；(5)所述TA值对应的调整量；其中，第一时间长度或第二时间长度的时间精度高于所述TA值的时间精度。
具体地，在又一个实施例中：处理单元802用于，确定第一参考时间，第一参考时间为终端设备在参考点的参考时间；通信单元803用于，向CU发送第四信息，第四信息用于指示第一参考时间。
在一种可能的设计中，通信单元803具体用于，接收来自CU第二请求信息，第二请求信息用于请求第一参考时间，第二请求信息包括终端设备的标识；以及，根据第二请求信息向CU发送第四信息。
在一种可能的设计中，处理单元802具体用于，确定第二参考时间，第二参考时间为所述DU在所述参考点的参考时间；以及，确定第二时间长度，第二时间长度表征所述DU和所述终端设备之间的单向传输时延；其中，第二时间长度的时间精度高于所述终端设备的TA值的时间精度；根据第二参考时间和所述单向传输时延确定第一参考时间。
应理解以上装置中单元的划分仅仅是一种逻辑功能的划分，实际实现时可以全部或部分集成到一个物理实体上，也可以物理上分开。且装置中的单元可以全部以软件通过处理 元件调用的形式实现；也可以全部以硬件的形式实现；还可以部分单元以软件通过处理元件调用的形式实现，部分单元以硬件的形式实现。例如，各个单元可以为单独设立的处理元件，也可以集成在装置的某一个芯片中实现，此外，也可以以程序的形式存储于存储器中，由装置的某一个处理元件调用并执行该单元的功能。此外这些单元全部或部分可以集成在一起，也可以独立实现。这里所述的处理元件又可以成为处理器，可以是一种具有信号的处理能力的集成电路。在实现过程中，上述方法的各步骤或以上各个单元可以通过处理器元件中的硬件的集成逻辑电路实现或者以软件通过处理元件调用的形式实现。
在一个例子中，以上任一装置中的单元可以是被配置成实施以上方法的一个或多个集成电路，例如：一个或多个特定集成电路(Application Specific Integrated Circuit，ASIC)，或，一个或多个微处理器(digital singnal processor，DSP)，或，一个或者多个现场可编程门阵列(Field Programmable Gate Array，FPGA)，或这些集成电路形式中至少两种的组合。再如，当装置中的单元可以通过处理元件调度程序的形式实现时，该处理元件可以是处理器，比如通用中央处理器(central processing unit，CPU)，或其它可以调用程序的处理器。再如，这些单元可以集成在一起，以片上系统(system-on-a-chip，SOC)的形式实现。
以上用于接收的单元是一种该装置的接口电路，用于从其它装置接收信号。例如，当该装置以芯片的方式实现时，该接收单元是该芯片用于从其它芯片或装置接收信号的接口电路。以上用于发送的单元是一种该装置的接口电路，用于向其它装置发送信号。例如，当该装置以芯片的方式实现时，该发送单元是该芯片用于向其它芯片或装置发送信号的接口电路。
参见图9，为本申请实施例提供的一种网络设备的结构示意图，该网络设备(或基站)可应用于如图1所示的系统架构中。该网络设备包括一个或多个DU 901和一个或多个CU 902，其中，DU901可以用于执行上述方法实施例中DU的功能，CU 902可以用于执行上述方法实施例中CU的功能。
所述DU 901可以包括至少一个天线9011，至少一个射频单元9012，至少一个处理器9013和至少一个存储器9014。所述DU 901部分主要用于射频信号的收发以及射频信号与基带信号的转换，以及部分基带处理。CU902可以包括至少一个处理器9022和至少一个存储器9021。CU902和DU901之间可以通过F1接口(比如F1-C或F1-U)进行通信。所述CU 902部分主要用于进行基带处理等。所述DU 901与CU 902可以是物理上设置在一起，也可以物理上分离设置的，本申请实施例中是以DU 901与CU 902物理上分离设置为例进行描述的。
此外，可选的，网络设备90可以包括一个或多个射频单元，一个或多个DU和一个或多个CU。其中，DU可以包括至少一个处理器9013和至少一个存储器9014，射频单元可以包括至少一个天线9011和至少一个射频单元9012，CU可以包括至少一个处理器9022和至少一个存储器9021。
在一个实例中，所述CU902可以由一个或多个单板构成，多个单板可以共同支持单一接入指示的无线接入网(如5G网)，也可以分别支持不同接入制式的无线接入网(如LTE网，5G网或其他网)。所述存储器9021和处理器9022可以服务于一个或多个单板；也就是说，可以每个单板上单独设置存储器和处理器，或者也可以是多个单板共用相同的存储器和处理器。此外每个单板上还可以设置有必要的电路。所述DU901可以由一个或多个单 板构成，多个单板可以共同支持单一接入指示的无线接入网(如5G网)，也可以分别支持不同接入制式的无线接入网(如LTE网，5G网或其他网)。所述存储器9014和处理器9013可以服务于一个或多个单板。也就是说，可以每个单板上单独设置存储器和处理器，或者也可以是多个单板共用相同的存储器和处理器。此外每个单板上还可以设置有必要的电路。
图9所示的CU能够实现图5或图6或图7所示意的方法实施例中涉及CU的各个过程。图9所示的CU中的各个模块的操作和/或功能，分别为了实现上述方法实施例中的相应流程。具体可参见上述方法实施例中的描述，为避免重复，此处适当省略详述描述。
图9所示的DU能够实现图5或图6或图7所示意的方法实施例中涉及DU的各个过程。图9所示的DU中的各个模块的操作和/或功能，分别为了实现上述方法实施例中的相应流程。具体可参见上述方法实施例中的描述，为避免重复，此处适当省略详述描述。
本申请实施例中的术语“系统”和“网络”可被互换使用。“至少一个”是指一个或者多个，“多个”是指两个或两个以上。“和/或”，描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A、同时存在A和B、单独存在B的情况，其中A，B可以是单数或者复数。字符“/”一般表示前后关联对象是一种“或”的关系。“以下至少一项(个)”或其类似表达，是指的这些项中的任意组合，包括单项(个)或复数项(个)的任意组合。例如“A，B和C中的至少一个”包括A，B，C，AB，AC，BC或ABC。以及，除非有特别说明，本申请实施例提及“第一”、“第二”等序数词是用于对多个对象进行区分，不用于限定多个对象的顺序、时序、优先级或者重要程度。
本领域内的技术人员应明白，本申请的实施例可提供为方法、系统、或计算机程序产品。因此，本申请可采用完全硬件实施例、完全软件实施例、或结合软件和硬件方面的实施例的形式。而且，本申请可采用在一个或多个其中包含有计算机可用程序代码的计算机可用存储介质(包括但不限于磁盘存储器、CD-ROM、光学存储器等)上实施的计算机程序产品的形式。
本申请是参照根据本申请的方法、设备(系统)、和计算机程序产品的流程图和/或方框图来描述的。应理解可由计算机程序指令实现流程图和/或方框图中的每一流程和/或方框、以及流程图和/或方框图中的流程和/或方框的结合。可提供这些计算机程序指令到通用计算机、专用计算机、嵌入式处理机或其他可编程数据处理设备的处理器以产生一个机器，使得通过计算机或其他可编程数据处理设备的处理器执行的指令产生用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的装置。
这些计算机程序指令也可存储在能引导计算机或其他可编程数据处理设备以特定方式工作的计算机可读存储器中，使得存储在该计算机可读存储器中的指令产生包括指令装置的制造品，该指令装置实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能。
这些计算机程序指令也可装载到计算机或其他可编程数据处理设备上，使得在计算机或其他可编程设备上执行一系列操作步骤以产生计算机实现的处理，从而在计算机或其他可编程设备上执行的指令提供用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的步骤。
显然，本领域的技术人员可以对本申请进行各种改动和变型而不脱离本申请的精神和范围。这样，倘若本申请的这些修改和变型属于本申请权利要求及其等同技术的范围之内， 则本申请也意图包含这些改动和变型在内。

Claims (24)

  1. 一种时间同步方法，其特征在于，所述方法适用于第一通信装置，所述第一通信装置为集中式单元CU或CU中的芯片，所述方法包括：
    确定第一参考时间，所述第一参考时间为终端设备在参考点的参考时间；
    向所述终端设备发送第一信息，所述第一信息用于指示所述第一参考时间。
  2. 根据权利要求1所述的方法，其特征在于，所述确定第一参考时间，包括：
    接收来自分布式单元DU的第二信息和第三信息；其中，所述第二信息用于指示第二参考时间，所述第二参考时间为所述DU在所述参考点的参考时间，所述第三信息用于确定所述DU和所述终端设备之间的单向传输时延；
    根据所述第二参考时间和所述单向传输时延确定所述第一参考时间。
  3. 根据权利要求2所述的方法，其特征在于，接收来自DU的第三信息，包括：
    向所述DU发送第一请求信息，所述第一请求信息用于请求所述单向传输时延，所述第一请求信息包括所述终端设备的标识；
    接收所述DU发送的所述第三信息。
  4. 根据权利要求3所述的方法，其特征在于，所述方法还包括：
    接收来自所述DU的能力信息，所述能力信息用于指示所述DU支持上报所述单向传输时延。
  5. 根据权利要求2至4中任一项所述的方法，其特征在于，所述第三信息包括以下至少一项：
    第一时间长度，所述第一时间长度表征所述DU和所述终端设备之间的环回传输时延；所述第一时间长度是通过测量所述终端设备发送的第一上行信号或第二上行信号得到的；所述第一上行信号为随机接入前导码，所述第二上行信号不同于所述第一上行信号；
    第二时间长度，所述第二时间长度为所述第一时间长度的一半；
    所述终端设备的定时提前TA值；
    所述TA值的一半；
    所述TA值对应的调整量；
    其中，所述第一时间长度或所述第二时间长度的时间精度高于所述TA值的时间精度。
  6. 根据权利要求1所述的方法，其特征在于，所述确定第一参考时间，包括：
    接收来自DU的第四信息，所述第四信息用于指示所述第一参考时间。
  7. 根据权利要求6所述的方法，其特征在于，接收来自DU的第四信息，包括：
    向所述DU发送第二请求信息，所述第二请求信息用于请求所述第一参考时间，所述第二请求信息包括所述终端设备的标识；
    接收所述DU发送的所述第四信息。
  8. 一种时间同步方法，其特征在于，所述方法适用于第二通信装置，所述第二通信装置为DU或DU中的芯片，所述方法包括：
    确定第二信息和第三信息；其中，所述第二信息用于指示第二参考时间，所述第二参考时间为所述DU在所述参考点的参考时间，所述第三信息用于确定所述DU和终端设备之间的单向传输时延；
    向CU发送第二信息和第三信息。
  9. 根据权利要求8所述的方法，其特征在于，向所述CU发送第三信息，包括：
    接收来自CU的第一请求信息，所述第一请求信息用于请求所述单向传输时延，所述第一请求信息包括所述终端设备的标识；
    根据所述第一请求信息向所述CU发送所述第三信息。
  10. 根据权利要求8或9所述的方法，其特征在于，所述方法还包括：
    向所述CU发送所述DU的能力信息，所述能力信息用于指示所述DU支持上报所述单向传输时延。
  11. 根据权利要求8所述的方法，其特征在于，向CU发送第二信息和第三信息，包括：
    接收来自所述CU的第一请求信息，所述第一请求信息用于请求所述第二信息和所述第三信息，所述第一请求信息包括所述终端设备的标识；
    确定支持上报所述单向传输时延后，向所述CU发送所述第二信息和所述第三信息。
  12. 根据权利要求8至11中任一项所述的方法，其特征在于，所述第三信息包括以下至少一项：
    第一时间长度，所述第一时间长度表征所述DU和所述终端设备之间的环回传输时延；所述第一时间长度是通过测量所述终端设备发送的第一上行信号或第二上行信号得到的；所述第一上行信号为随机接入前导码，所述第二上行信号不同于所述第一上行信号；
    第二时间长度，所述第二时间长度为所述第一时间长度的一半；
    所述终端设备的定时提前TA值；
    所述TA值的一半；
    所述TA值对应的调整量；
    其中，所述第一时间长度或所述第二时间长度的时间精度高于所述TA值的时间精度。
  13. 一种时间同步方法，其特征在于，所述方法适用于第二通信装置，所述第二通信装置为DU或DU中的芯片，所述方法包括：
    确定第一参考时间，所述第一参考时间为终端设备在参考点的参考时间；
    向CU发送第四信息，所述第四信息用于指示所述第一参考时间。
  14. 根据权利要求13项所述的方法，其特征在于，向所述CU发送第四信息，包括：
    接收来自CU的第二请求信息，所述第二请求信息用于请求所述第一参考时间，所述第二请求信息包括终端设备的标识；
    根据所述第二请求信息向所述CU发送所述第四信息。
  15. 根据权利要求13或14所述的方法，其特征在于，所述确定第一参考时间，包括：
    确定第二参考时间，所述第二参考时间为所述DU在所述参考点的参考时间；以及，确定第二时间长度，所述第二时间长度表征所述DU和所述终端设备之间的单向传输时延；其中，所述第二时间长度的时间精度高于所述终端设备的TA值的时间精度；
    根据所述第二参考时间和所述单向传输时延确定所述第一参考时间。
  16. 一种通信装置，其特征在于，包括用于执行如权利要求1至7中任一项所述方法的单元或模块。
  17. 一种通信装置，其特征在于，包括用于执行如权利要求8至15中任一项所述方法的单元或模块。
  18. 一种通信装置，其特征在于，包括处理器和存储器，所述处理器和所述存储器耦合，所述处理器用于实现如权利要求1至7中任一项所述的方法。
  19. 一种通信装置，其特征在于，包括处理器和存储器，所述处理器和所述存储器耦合，所述处理器用于实现如权利要求8至15中任一项所述的方法。
  20. 一种通信装置，其特征在于，包括处理器和接口电路，所述接口电路用于接收来自所述通信装置之外的其它通信装置的信号并传输至所述处理器或将来自所述处理器的信号发送给所述通信装置之外的其它通信装置，所述处理器通过逻辑电路或执行代码指令用于实现如权利要求1至7中任一项所述的方法。
  21. 一种通信装置，其特征在于，包括处理器和接口电路，所述接口电路用于接收来自所述通信装置之外的其它通信装置的信号并传输至所述处理器或将来自所述处理器的信号发送给所述通信装置之外的其它通信装置，所述处理器通过逻辑电路或执行代码指令用于实现如权利要求8至15中任一项所述的方法。
  22. 一种计算机可读存储介质，其特征在于，所述存储介质中存储有计算机程序或指令，当所述计算机程序或指令被通信装置执行时，实现如权利要求1至7中任一项所述的方法，或，实现如权利要求8至15中任一项所述的方法。
  23. 一种通信系统，其特征在于，包括如权利要求16、18、20中任一项所述的通信装置，和如权利要求17、19、21中任一项所述的通信装置。
  24. 一种计算机程序产品，其特征在于，当计算机读取并执行所述计算机程序产品时，使得计算机执行如权利要求1至7中任一项所述的方法，或如权利要求8至15中任一项所述方法。
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