WO2020114391A1 - 通信方法及装置 - Google Patents

通信方法及装置 Download PDF

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Publication number
WO2020114391A1
WO2020114391A1 PCT/CN2019/122703 CN2019122703W WO2020114391A1 WO 2020114391 A1 WO2020114391 A1 WO 2020114391A1 CN 2019122703 W CN2019122703 W CN 2019122703W WO 2020114391 A1 WO2020114391 A1 WO 2020114391A1
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WIPO (PCT)
Prior art keywords
network device
time
target network
data unit
time information
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PCT/CN2019/122703
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English (en)
French (fr)
Inventor
胡星星
张宏平
曾清海
Original Assignee
华为技术有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Priority to BR112021010862-9A priority Critical patent/BR112021010862A2/pt
Priority to EP19892306.2A priority patent/EP3886497A4/en
Publication of WO2020114391A1 publication Critical patent/WO2020114391A1/zh
Priority to US17/339,542 priority patent/US20210328699A1/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J3/00—Time-division multiplex systems
    • H04J3/02—Details
    • H04J3/06—Synchronising arrangements
    • H04J3/0635—Clock or time synchronisation in a network
    • H04J3/0682—Clock or time synchronisation in a network by delay compensation, e.g. by compensation of propagation delay or variations thereof, by ranging
    • 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
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/02—Arrangements for optimising operational condition
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0011—Control or signalling for completing the hand-off for data sessions of end-to-end connection
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/08—Reselecting an access point
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/04—Wireless resource allocation
    • H04W72/044—Wireless resource allocation based on the type of the allocated resource
    • H04W72/0446—Resources in time domain, e.g. slots or frames
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/20—Control channels or signalling for resource management
    • H04W72/23—Control channels or signalling for resource management in the downlink direction of a wireless link, i.e. towards a terminal

Definitions

  • This application relates to the field of communication technology, and in particular, to a communication method and device.
  • ultra-reliable low-latency communications ultra reliable low latency communications
  • URLLC ultra reliable low latency communications
  • the source base station needs to transfer the downlink data units received from the core network and not correctly received by the terminal device and the out-of-order uplink data units received from the terminal device to the target base station.
  • Out-of-order means that some data units before the source base station correctly received the data unit from the terminal have not been correctly received by the source base station (for example, packet 2/3 has been received, but packet 1 has not been received).
  • a protocol data unit (protocol data unit (PDU)) corresponding to the sending end carries a piece of time information.
  • time information is carried in a packet data convergence protocol (packet data convergence protocol, PDCP) PDU or a service data adaptation protocol (service data adaptation protocol, SDAP) PDU.
  • the present application provides a communication method and device to accurately determine time information during the switching transmission of data units.
  • a communication method which includes: a sending end device acquiring information about a first time corresponding to a data unit, the first time using a timing of a source network device as a reference; the sending end device determining the data Information about the second time corresponding to the unit, the second time taking the timing of the target network device as a reference; and the sending end device sends the information about the second time to the receiving end device.
  • the first time information is time information with reference to the timing of the source network device
  • the source device converts the time information to timing with the target network device
  • the receiving device can uniformly adopt the timing of the current serving cell, which reduces the processing complexity of the receiving device.
  • the second time is determined according to the first time and a timing deviation
  • the timing deviation includes a timing deviation between the target network device and the source network device.
  • the sending device is a target network device
  • the receiving device is a terminal device
  • the method further includes: the sending device receives a delay from the receiving device Information, wherein the delay information is calculated by the receiving end device according to the information at the second time and at the third time when the receiving end device acquires the data unit.
  • the receiving end device may calculate the time between reception and transmission based on the second time information and the third time information of the data unit. ⁇ Extension information.
  • the sending end device can know the delay between receiving and sending.
  • the acquiring, by the sending-end device, information about the first time corresponding to the data unit includes: the sending-end device receives, from the source network device, the first time corresponding to the data unit information.
  • the sending end device may receive the data unit sent by the source network device and simultaneously receive the first time information corresponding to the data unit.
  • the first-time information is carried in the header of the service data adaptation protocol SDAP protocol data unit PDU, or in the general packet radio service user plane tunneling protocol GTP-U message. In the extension header.
  • the first time information is specifically carried in the header of the SDAP PDU of the data unit, or in the header of the GTP-U message that sends the data unit.
  • the acquiring the first time corresponding to the data unit by the sending device includes: the sending end device acquiring the first time corresponding to the data unit from a packet data aggregation protocol PDCP layer Information.
  • the sending device may also obtain the first time information corresponding to the data unit from its own PDCP layer, and the first time is the time when the PDCP layer of the sending device receives the data unit from the source network device.
  • the first time information includes one or two of the following time information: relative time information and absolute time information.
  • the first time information is relative time information with reference to the timing of the source network device
  • the sending end device converts the first time information into relative time with reference to the timing of the target network device, so that the receiving end device can
  • the timing of the current serving cell is used uniformly to calculate the delay corresponding to the data unit, which reduces the processing complexity of the receiving end device.
  • the first time information is absolute time information
  • the sending end device converts the absolute time information to a relative time with reference to the timing of the target network device, so that the receiving end device can uniformly adopt the current serving cell timing to calculate the data unit correspondence
  • the delay reduces the processing complexity of the receiving device.
  • another communication method including: a target network device acquiring information of a first time corresponding to a data unit, the first time using a timing of a source network device as a reference; the target network device determining the Information of the second time corresponding to the data unit, the second time taking the timing of the target network device as a reference; and the target network device is determined according to the information of the second time and the time when the data unit is sent Delay information of the data unit.
  • the first time information is time information with reference to the timing of the source network device
  • the target network device converts the time information to time information with reference to the timing of the target network device, so that the target The network device can uniformly adopt the timing of the current serving cell to calculate the delay corresponding to the data unit, which reduces the processing complexity of the target network device.
  • the second time is determined according to the first time and a timing deviation
  • the timing deviation includes a timing deviation between the target network device and the source network device.
  • the acquiring, by the target network device, information about the first time corresponding to the data unit includes: receiving, by the target network device, the first time corresponding to the data unit from the source network device information.
  • the first-time information is carried in the header of the service data adaptation protocol SDAP protocol data unit PDU, or in the general packet radio service user plane tunneling protocol GTP-U message corresponding In the extension header.
  • the target network device acquiring the first time corresponding to the data unit includes: the target network device acquiring the first time corresponding to the data unit from the packet data aggregation protocol PDCP layer Information.
  • the first time information includes one or two of the following time information: relative time information and absolute time information.
  • the method further includes: the target network device sending the delay information to a network management system.
  • the network management system obtains the delay information, which can further optimize the data transmission process.
  • yet another communication method including: a receiving end device acquiring information of a first time corresponding to a data unit, the first time referring to a timing of a source network device; and the receiving end device according to The information about the first time, the timing deviation, and the information about the second time when the receiving device obtains the data unit, and determines that the receiving device obtains the delay information of the data unit.
  • the first time information is time information with reference to the timing of the source network device
  • the receiving end device converts the time information into time information with reference to the timing of the target network device, thereby receiving
  • the end device can uniformly adopt the timing of the current serving cell to calculate the corresponding delay of the data unit, which reduces the processing complexity of the receiving end device.
  • the second time refers to the timing of the target network device.
  • the receiving end device acquiring the first time information corresponding to the data unit includes: the receiving end device receives the first time information corresponding to the data unit from the sending end device.
  • the receiving end device is a terminal device
  • the sending end device is a target network device
  • the method further includes the receiving end device receiving a first message from the sending end device Indication, the first indication is used to indicate that the data unit is a data unit transferred from the source network device to the target network device.
  • the data unit may be indicated as the data unit to be switched and transmitted through explicit indication information, so that the receiving end device processes the time information according to the indication information.
  • the method further includes: the receiving device sends the delay information to the sending device.
  • the first time information is carried in the header of the service data adaptation protocol SDAP protocol data unit PDU, or in the header of the PDCP PDU.
  • the first time information includes one or two of the following time information: relative time information and absolute time information.
  • the sending-end device is a terminal device
  • the receiving-end device is a target network device
  • the method further includes: the receiving-end device sending the delay information to a network management system.
  • a communication device which can implement any one or any possible implementation manner of any one of the first to third aspects above.
  • the communication device may be a chip or a device, and the above method may be implemented through software, hardware, or executing corresponding software through hardware.
  • the structure of the communication device includes a processor and a memory; the processor is configured to support the device to perform the corresponding function in the above communication method.
  • the memory is used to couple with the processor, which stores necessary programs (instructions) and data of the device.
  • the communication device may further include a communication interface for supporting communication between the device and other network elements.
  • the communication device may include a unit module that performs corresponding actions in the above method.
  • a communication device provided by the present application includes: a processing unit and a communication unit; wherein:
  • the processing unit is configured to obtain information about the first time corresponding to the data unit, and the first time uses the timing of the source network device as a reference;
  • the processing unit is further configured to determine information about a second time corresponding to the data unit, and the second time uses the timing of the target network device as a reference;
  • the communication unit is configured to send the second time information to the receiving device.
  • the communication unit is further configured to receive time delay information from the receiving device, wherein the time delay information is the information of the receiving device and the receiving device according to the second time Obtained by calculating the third time information of the data unit.
  • the communication unit is further configured to receive the first time information corresponding to the data unit from the source network device.
  • the processing unit is further configured to obtain the first time information corresponding to the data unit from the packet data aggregation protocol PDCP layer.
  • a communication device provided by the present application includes: a processing unit, and may further include a communication unit; wherein:
  • the processing unit is configured to obtain information about the first time corresponding to the data unit, and the first time uses the timing of the source network device as a reference;
  • the processing unit is further configured to determine information about a second time corresponding to the data unit, and the second time uses the timing of the target network device as a reference;
  • the communication unit is configured to receive the first time information corresponding to the data unit from the source network device.
  • the processing unit is further configured to obtain the first time information corresponding to the data unit from the packet data aggregation protocol PDCP layer.
  • the communication unit is further configured to send the delay information to the network management system.
  • a communication device provided by the present application includes: a processing unit, and may further include a communication unit; wherein:
  • the processing unit is configured to obtain information about the first time corresponding to the data unit, and the first time uses the timing of the source network device as a reference;
  • the processing unit is further configured to determine when the receiving device acquires the data unit based on the information of the first time, timing deviation, and information of the second time when the receiving device acquires the data unit ⁇ Extension information.
  • the communication unit is configured to receive the first time information corresponding to the data unit from the source device.
  • the communication unit is further configured to receive a first indication from the source device, the first indication is used to indicate that the data unit is transferred from the source network device to the target network device Data unit.
  • the communication unit is further configured to send the delay information to the sending end device.
  • the communication unit is further configured to send the delay information to the network management system.
  • a processor and a transceiver device are included, and the processor is coupled to the transceiver device, and the processor is used to execute a computer program or instruction to control the transceiver device to receive and receive information. Send; when the processor executes the computer program or instruction, the processor is also used to implement the above method.
  • the transceiver device may be a transceiver, a transceiver circuit, or an input-output interface.
  • the transceiver device is a transceiver circuit or an input-output interface.
  • the structure of the communication device includes a processor; the processor is configured to support the device to perform the corresponding function in the above communication method.
  • the structure of the communication device includes a processor, and the processor is used to couple with the memory, read instructions in the memory, and implement the above method according to the instructions.
  • the structure of the communication device includes a transceiver, which is used to implement the foregoing communication method.
  • the transceiver unit may be an input-output unit, such as an input-output circuit or a communication interface.
  • the transceiver unit may be a transmitter/receiver (also may be referred to as a transmitter/receiver).
  • a computer-readable storage medium stores computer programs or instructions. When the computer programs or instructions are executed, the methods described in the above aspects are implemented.
  • a computer program product containing instructions, which when executed on a computer, causes the computer to execute the method described in the above aspects.
  • a communication system including the communication devices in the above-mentioned fourth and fifth aspects.
  • Figure 1-1 is a schematic diagram of a communication system involved in this application.
  • Figure 1-2 shows a schematic diagram of a protocol stack of an access network device with a CU entity and a DU entity separated architecture according to an embodiment of the present application
  • FIG. 2 is a schematic flowchart of a communication method provided by an embodiment of the present application.
  • Figure 3 is a schematic diagram of a message format that carries time information in the header of the SDAP PDU;
  • FIG. 4 is a schematic diagram of an example of determining time information
  • FIG. 5 is a schematic flow chart of an exemplary sending end device determining information at a second time
  • FIG. 6 is a schematic diagram of a packet format carrying time information in a packet header of a PDCP PDU
  • FIG. 7 is a schematic diagram of the format of time information carried in the extension header of GTP-U;
  • FIG. 8 is a schematic diagram of another example for determining time information
  • FIG. 9 is a schematic flowchart of another communication method provided by an embodiment of the present application.
  • FIG. 10 is a schematic flowchart of another communication method according to an embodiment of the present application.
  • FIG. 11 is a schematic flow chart of an exemplary receiving end device determining information of a second time
  • FIG. 14 is a schematic structural diagram of yet another communication device provided by an embodiment of this application.
  • 15 is a schematic structural diagram of yet another communication device provided by an embodiment of the present application.
  • Figure 1-1 shows a schematic diagram of a communication system involved in this application.
  • the communication system may include at least one network device 100 (only one is shown in the figure) and one or more terminal devices 200 connected to the network device 100.
  • the network device 100 may be a device that can communicate with the terminal device 200.
  • the network device 100 may be any device having a wireless transceiver function. Including but not limited to: base station NodeB, evolved base station eNodeB, base station in the fifth generation (5G) communication system, base station or network equipment in future communication system, access node in WiFi system, wireless relay Nodes, wireless backhaul nodes, etc.
  • the network device 100 may also be a wireless controller in a cloud radio access network (CRAN) scenario.
  • the network device 100 may also be a small station, a transmission reference (transmission reference point, TRP), or the like.
  • TRP transmission reference point
  • Terminal device 200 is a device with wireless transceiver function, which can be deployed on land, including indoor or outdoor, handheld, wearable, or vehicle-mounted; it can also be deployed on the water, such as ships, etc.; it can also be deployed in the air, such as aircraft , Balloons and satellites.
  • the terminal device may be a mobile phone, a tablet, a computer with wireless transceiver function, a virtual reality (VR) terminal device, an augmented reality (AR) terminal device, and industrial control ( wireless terminal in industrial control, wireless terminal in self-driving, wireless terminal in remote medical, wireless terminal in smart grid, transportation safety Wireless terminals, wireless terminals in smart cities (smart cities), wireless terminals in smart homes (smart homes), etc.
  • Terminal equipment may sometimes be called user equipment (user equipment (UE), access terminal equipment, UE unit, mobile station, mobile station, remote station, remote terminal equipment, mobile device, terminal), wireless communication device, UE Agent or UE device, etc.
  • UE user equipment
  • access terminal equipment UE unit
  • mobile station mobile station
  • remote station remote terminal equipment
  • mobile device terminal
  • wireless communication device UE Agent or UE device, etc.
  • “Multiple” refers to two or more. In view of this, in the embodiments of the present invention, “multiple” may also be understood as “at least two”.
  • “And/or” describes the relationship of the related objects, indicating that there can be three relationships, for example, A and/or B, which can indicate: there are three conditions: A exists alone, A and B exist at the same time, and B exists alone.
  • the character "/”, unless otherwise specified, generally indicates that the related object is a "or" relationship.
  • Radio Resource Control (RRC) layer The protocol layer in the communication system, used to perform broadcast, paging, RRC link establishment, radio bearer control, mobile, terminal equipment measurement and reporting control, etc.
  • Service data adaptation protocol (service data adaptation, SDAP) layer This layer is a newly introduced protocol layer in 5G. Responsible for mapping each quality of service (QoS) flow (flow) sent from the core network or application layer to the data resource bearer (DRB) of the wireless access layer, that is, according to the business attribute corresponding to the Qos flow , The data unit corresponding to the Qos stream is transmitted on the corresponding DRB.
  • QoS quality of service
  • DRB data resource bearer
  • Radio Link Control A protocol layer in a communication system that performs services such as segmentation, reassembly, and retransmission. There may be multiple RLC entities in the RLC layer, and each RLC entity provides services for each PDCP entity. The RLC layer can also be configured to order the data submitted to the upper layer.
  • MAC Media Access Control
  • Physical (PHY) layer encode and transmit the data passed down from the MAC layer.
  • Service data unit service data unit, SDU
  • protocol data unit protocol data unit
  • the protocol layer from top to bottom are: SDAP layer, PDCP layer, RLC layer, MAC layer and PHY Layer, or the above protocol layer may not include the SDAP layer.
  • the protocol layers are from top to bottom: RRC layer, PDCP layer, RLC layer, MAC layer and PHY layer.
  • the data input from the previous layer is called the SDU of this layer.
  • the data processed by each layer is called PDU in this layer.
  • the data input by the PDCP layer to the RLC layer is called PDCP PDU for the PDCP layer and RLC SDU for the RLC layer.
  • the data unit may refer to any one of PDU or SDU.
  • the access network device may be a structure in which a centralized unit (CU) entity and a distributed unit (DU) entity are separated.
  • FIG. 1-2 shows a schematic diagram of a protocol stack of an access network device with a CU entity and DU entity separated architecture according to an embodiment of the present application.
  • CU and DU can be understood as a division of the access network device from the perspective of logical functions.
  • the CU entity is an entity corresponding to the CU function
  • the DU entity is an entity corresponding to the DU function.
  • the CU entity and the DU entity may be physically separated or deployed together.
  • Multiple DU entities can share a CU entity.
  • One DU entity can also connect multiple CU entities (not shown in Figures 1-2).
  • the CU entity and the DU entity may be connected through an interface, for example, may be an F1 interface.
  • the CU entity and the DU entity can be divided according to the protocol layer of the wireless network.
  • the functions of the RRC protocol layer, SDAP protocol layer, and PDCP protocol layer are set in the CU entity, while the functions of the RLC protocol layer, MAC protocol layer, and PHY protocol layer are set in the DU entity.
  • the division of the processing functions of the CU entity and the DU entity according to this protocol layer is only an example, and may also be divided in other ways.
  • the CU entity or the DU entity can be divided into functions with more protocol layers.
  • the CU entity or the DU entity can also be divided into some processing functions with a protocol layer.
  • part of the functions of the RLC protocol layer and the functions of the protocol layer above the RLC protocol layer are set in the CU entity, and the remaining functions of the RLC protocol layer and the functions of the protocol layer below the RLC protocol layer are set in the DU entity .
  • the functions of the CU entity or the DU entity may also be divided according to service types or other system requirements. For example, according to the delay division, the function that the processing time needs to meet the delay requirement is set in the DU entity, and the function that does not need to meet the delay requirement is set in the CU entity.
  • the CU entity may also have one or more functions of the core network.
  • One or more CU entities can be set centrally or separately.
  • the CU entity can be set on the network side to facilitate centralized management.
  • the DU entity may have multiple radio frequency functions, or the radio frequency functions may be remotely set.
  • the functions of the CU entity can be realized by one functional entity or different functional entities.
  • the function of the CU entity can be further divided, for example, the control plane (CP) and the user plane (UP) are separated, that is, the CU entity includes the CU control plane (CU-CP) entity and CU user plane (CU-UP) entity.
  • the CU-CP entity and the CU-UP entity can be coupled with the DU entity to jointly complete the functions of the access network device.
  • the CU-CP entity is responsible for the control plane function, which mainly includes the RRC protocol layer and the PDCP control plane (PDCP control plane, PDCP-C) protocol layer.
  • the PDCP-C protocol layer is mainly responsible for encryption and decryption of the control plane data, integrity protection, and data transmission.
  • the CU-UP entity is responsible for user plane functions and mainly includes the SDAP protocol layer and the PDCP user plane (PDCP-user) plane (PDCP-U) protocol layer.
  • the SDAP protocol layer is mainly responsible for mapping the data flow of the core network to the bearer.
  • the PDCP-U protocol layer is mainly responsible for encryption and decryption of the data plane, integrity protection, header compression, serial number maintenance, and data transmission.
  • the CU-CP entity and the CU-UP entity are connected through the E1 interface, the CU-CP entity is connected to the DU entity through the F1-C (control plane) interface, and the CU-UP entity is connected through the F1-U (user (Surface) interface and DU physical connection.
  • the CU-CP entity represents the access network equipment and the control plane of the core network (such as the 4th generation (4G) core network mobility management entity (mobility management entity, MME), or 5G core network (5G core, 5GC) access mobility management function (access and mobility management function, AMF) network element;
  • CU-UP entity represents the access network equipment and the user plane of the core network (such as 4G core network service gateway (SGW) ), or the user plane function (UPF) element of the 5G core network;
  • the DU entity represents the access network equipment and terminal equipment connection.
  • 4G 4th generation
  • MME mobility management entity
  • 5G core, 5GC 5G core network (5G core, 5GC) access mobility management function (access and mobility management function, AMF) network element
  • CU-UP entity represents the access network equipment and the user plane of the core network (such as 4G core network service gateway (SGW) ), or the user plane function (UPF) element of the 5G core network
  • the DU entity represents the access network equipment and terminal equipment
  • the present application provides a communication method and apparatus.
  • the first time information is time information with reference to the timing of the source network device
  • the sender device converts the time information to reference with the timing of the target network device Time information, so that the receiving end device can uniformly adopt the timing of the current serving cell, reducing the processing complexity of the receiving end device.
  • the source network device needs to transfer the downlink data units received from the core network and not yet correctly received by the UE and the out-of-order data units received from the UE To the target network device.
  • Out-of-order means that some data units before the data unit correctly received by the source network device from the terminal have not been correctly received by the source network device (for example, packet 2/3 has been received but packet 1 has not been received).
  • the source network device passes the DRB-level downlink tunnel, that is, each source network device needs to be lossless
  • the DRBs of all have established corresponding tunnels, and transferred the downlink data units on these DRBs that have not been correctly received by the UE to the target network device.
  • the source network device transfers the out-of-order data units received on these DRBs to the target network device through the DRB-level upstream tunnel.
  • the source network device also needs to notify the target network device: the mapping relationship between the QoS flow and DRB configured by the source network device for the UE in each DRB, and the Sequence Number (SN) status.
  • the SN state includes the receiving state of the upstream PDCP SN and Hyper Frame Number (HFN) and the sending state of the downstream PDCP SN and HFN, specifically the next count value assigned to the downstream data unit corresponding to a DRB, the count The value includes the SN and superframe number of the PDCP corresponding to the data unit, and the source network device's reception of the upstream data unit corresponding to the DRB (the count value corresponding to the first PDCP data unit that was not correctly received, the count value includes the corresponding data The SN number and superframe number of the unit's PDCP, and the upstream reception of other data units after the PDCP data unit).
  • the data transferred through the DRB level tunnel is transferred in the form of SDAP PDU (that is, carries the header of the SDAP layer).
  • the transferred data units are all carried using the GPRS User Plane Tunneling Protocol (GPRS Tunnelling User, GTP-U) format, that is, using the GTP-U protocol.
  • GTP-U GPRS Tunnelling User
  • the UE moves or switches, it can be moved or switched from the source network device to the target network device, the source network device and the target network device are two different network devices; it can also be a cell from a network device (called “source” "Cell") moves or switches to another cell (called “target cell”).
  • the source network device and the target network device may have different timings, and the source cell and the target cell may also have different timings.
  • the timing here refers to the radio frame number, subframe number, time slot number, symbol number, etc. corresponding to the source network device, target network device, source cell, and target cell.
  • the description of the following embodiments takes the example of moving or switching from the source network device to the target network device.
  • the source network device and the target network device may also refer to the primary base station and the secondary base station in a dual link scenario, and the network side switches some Qos flows between the primary base station and the secondary base station.
  • FIG. 2 is a schematic flowchart of a communication method provided by an embodiment of the present application. The method includes the following steps:
  • the sending-end device obtains the first time information corresponding to the data unit.
  • the source network device needs to transfer the downlink data unit received from the core network and has not been correctly received by the UE and the out-of-order data unit received from the UE to the target network device, and may also need to transfer the slave core network
  • the new downlink data received (for example, the downlink data that has not been assigned a PDCP SN number) is transferred to the target network device.
  • the sending end device may be the target network device, and the corresponding receiving end device may be the terminal device; During the process, for example, to retransmit data to the target network device, the sending end device may be a terminal device, and the corresponding receiving end device may be a target network device.
  • the sending-end device first obtains the first time information corresponding to the data unit, where the first time refers to the timing of the source network device.
  • the sending-end device is a target network device, and the sending-end device obtains the first time information corresponding to the data unit, including: the sending-end device
  • the network device receives the first time information corresponding to the data unit.
  • the first time information may be carried in the data unit, or may be carried in the header or extension header of the GTP-U.
  • the source network device sends the data unit transferred during the handover to the target network device, and sends information about the first time corresponding to the data unit, where the first time is based on the timing of the source network device.
  • the source network device During downlink data transmission, if the UE moves from the source network device to the target network device, the source network device needs to transfer the downlink data received from the core network and not yet correctly received by the UE to the target network device, and may also need to transfer New downlink data received from the core network (for example, downlink data that has not yet been assigned a PDCP and SN number) is transferred to the target network device.
  • the first time information is also sent.
  • the first time is the time when the source network device receives the data in the data unit from the core network or the time when the source network device generates the data unit, and the first time refers to the timing of the source network device.
  • the first time may be any time between when the source network device receives the data packet corresponding to the data unit from the core network and when the source network device generates the data unit.
  • the acquiring the first time information corresponding to the data unit by the sending end device includes: the sending end device acquiring information of the first time corresponding to the data unit from the PDCP layer.
  • the PDCP layer of the sending end device obtains the data unit from the source network device.
  • the first time is the time when the other protocol stack layer of the sending end device acquires the data unit from the PDCP layer during subsequent processing.
  • the sending-end device acquires the first time information corresponding to the data unit from the SDAP layer.
  • the SDAP layer of the sending end device obtains the data unit from the source network device.
  • the first time is the time when the other protocol stack layer of the sending end device acquires the data unit from the SDAP layer during subsequent processing.
  • the sending end device is a terminal device
  • the sending end device acquiring the first time information corresponding to the data unit includes: the sending end device acquiring The source network device sends the first time information corresponding to the data unit.
  • the UE records the time when the data unit is sent to the source network device, or the time when the UE's wireless protocol layer (such as SDAP or PDCP layer) receives the data unit from the upper layer (such as the application layer or IP layer), or the UE's wireless The moment when the protocol layer (such as SDAP or PDCP layer) sends the data unit to the next layer, or the UE's wireless protocol layer (such as SDAP or PDCP layer) receives the data unit and the UE from the upper layer (such as the application layer or IP layer)
  • the wireless protocol layer (such as the SDAP or PDCP layer) sends the data unit to the next layer at any moment, that is, the first time.
  • the first time is based on the timing of the source network device.
  • the acquiring of the first time information corresponding to the data unit by the sending end device includes: the sending end device acquiring information of the first time corresponding to the data unit from the PDCP layer. That is, the first time may also indicate the moment when a certain protocol layer of the terminal device receives the data packet from the upper layer, such as the SDAP or PDCP layer receiving the data packet from the application layer, or the PDCP layer receiving the data packet from the SDAP layer time. Or the first time refers to any time between the moment when a protocol layer of the terminal device receives a data packet from the upper layer and the moment when the protocol layer sends the data packet to the next layer.
  • the first time information may be in a form of relative time, for example, identified by at least one of frame number, subframe number, and slot number, or it may be a time offset relative to a certain reference time (For example, the time offset relative to a certain frame number, subframe number, time slot number).
  • the source network device informs the UE of the rule of the reference time corresponding to the UE through an RRC message or a broadcast message, or the rule is specified in the protocol.
  • the frame number, subframe number, and time slot number of the reference time meet certain rules, such as the frame number Performing a modulo 10 operation is equal to 0.
  • the reference time may also be the absolute time corresponding to a certain frame (such as the absolute time when a broadcast message is sent.
  • the absolute time may be Coordinated Universal Time (UTC) UTC time or GPS time) .
  • UTC Coordinated Universal Time
  • GPS time GPS time
  • the sending device determines the second time information corresponding to the data unit.
  • the source device determines the second time information corresponding to the data unit, and the second time uses the timing of the target network device as a reference.
  • the second time is determined according to the first time and a timing deviation
  • the timing deviation includes a timing deviation between the target network device and the source network device.
  • Timing deviation refers to the offset of the radio frame number and the offset of the radio frame boundary between different network devices.
  • the offset may be a timing deviation observed from the perspective of the UE. Therefore, the receiving end device determines the information at the second time based on the information at the first time and the timing deviation.
  • the sending end device needs to perform the next processing on the data unit, that is, transmit it to the receiving end device, in order to ensure that the receiving end device can uniformly adopt the timing of the current serving cell and reduce the receiving end device Processing complexity, the second time is based on the timing of the target network device.
  • the target network device transmits the data unit to the UE, and simultaneously sends the second time information to the UE.
  • the UE failed to send the data unit to the source network device, and at this time, the UE has a cell handover, the UE needs to retransmit the data unit to the target network device, or the UE has not yet The data unit is sent to the source network device but the data unit has been assigned a PDCP SN number (or has formed a PDCP PDU), and the UE needs to reconstitute the PDCP PDU according to the format of the target network device and send the data unit.
  • the UE determines the information at the second time based on the information at the first time and the timing deviation. The second time is based on the timing of the target network device.
  • the sending device sends the second time information to the receiving device.
  • the sending end device After determining the information at the second time, the sending end device sends the information at the second time to the receiving end device.
  • the receiving end device receives the second time information. Therefore, the receiving end device can uniformly adopt the timing of the current serving cell for subsequent processing, and reduce the processing complexity of the receiving end device.
  • the sending end device sends the transferred data unit received from the source network device to the receiving end device, and sends information about the second time corresponding to the data unit.
  • the second time is based on the timing of the target network device. In this way, the corresponding second time takes into account the time spent in the data unit transfer process.
  • the sending end device may send the data unit to the receiving end device at a certain wireless protocol layer (such as SDAP layer or PDCP layer).
  • the sending device may send the second time information to the receiving device in SDAP PDU or PDCP PDU.
  • the sending device is a target network device, and the receiving device is a terminal device.
  • the above method may further include the following steps: the sending device receives delay information from the receiving device, the The delay information is calculated by the receiving device according to the information about the second time and the information about the third time when the receiving device obtains the data unit.
  • the UE receives the data unit from the target network device.
  • the UE may calculate the delay consumed in wireless transmission from the data unit according to the information about the second time corresponding to the data unit and the information about the third time when the UE acquires the data unit.
  • the third time of the data unit may refer to that the terminal device receives the data unit at a certain wireless protocol layer (such as the SDAP layer or PDCP layer) to submit the data unit to the upper layer (such as the IP layer) ) Between any moment.
  • a certain wireless protocol layer such as the SDAP layer or PDCP layer
  • the terminal device sends the delay information to the target network device.
  • the target network device receives the delay information, and can understand that the data unit transmits the corresponding delay information on the wireless network side.
  • the terminal device may feed back delay information of a certain data unit, or may feed back delay information corresponding to multiple data units.
  • the target network device may determine the delay of the data unit according to the second time information and the third time when the target network device acquires the data unit.
  • the target network device may calculate the delay of the data unit according to the second time information and the third time when the target network device acquires the data unit.
  • the delay is the difference between the third time and the second time.
  • the third time may refer to any time between when the target network device successfully receives the data unit and when the target network device sends the data in the data unit to the core network.
  • the first time information is time information with reference to the timing of the source network device
  • the sender device converts the time information to reference with the timing of the target network device Time information, so that the receiving end device can uniformly adopt the timing of the current serving cell, reducing the processing complexity of the receiving end device.
  • the following line switching transmission is used as an example.
  • the target network device serves as the sending end device, and the target network device determines the second time information. Including the following A1 ⁇ A16 and other implementation methods:
  • the source network device transfers the switched data unit to the target network device in the form of SDAP PDU/PDCP SDU.
  • the source network device carries relative time information (the first time information) in the SDAP PDU packet header, and the target network device obtains the second time information according to the first time information and timing deviation.
  • the target network device carries the second time information in the packet header of the SDAP PDU sent to the UE. Among them, as shown in FIG.
  • a latency measurement indication can be used to indicate whether the SDAP PDU carries time information, time information (timestamp) is located in the third byte (Oct3) and fourth byte (Oct4) of the SDAP PDU.
  • time information timestamp
  • Oct3 third byte
  • Oct4 fourth byte
  • the data is located in the fifth byte and subsequent bytes.
  • LMI may not be included.
  • SDAP SDU plus packet header (reflective quality of service flow to radio bearer mapping indication (reflective QoS flow to DRB mapping indication, RDI), reflective quality of service flow indication (reflective QoS indication, RQI) and quality of service flow identification (QoS flow ID , QFI) is SDAP PDU, the format of carrying time information can refer to Figure 3.
  • the relative time here may be identified by at least one of frame number, subframe number, and slot number, or it may be a time offset relative to a reference time (such as relative to a frame number, sub Time offset of frame number and time slot number).
  • the target network device determines the second time information according to the following manner: the target network device determines the first time information carried by the source network device in the SDAP PDU and the timing deviation of the two network devices.
  • the first time information carried in the SDAP PDU corresponds to the source network device timing as T_source
  • the corresponding time is the absolute time T1.
  • the absolute time T1 corresponds to T_target with reference to the timing of the target network device
  • the time information corresponding to the data unit sent by the target network device to the UE is the relative time corresponding to T_target with reference to the timing of the target network device.
  • the time information of the SDAP PDU transferred from the source network device is represented by a frame number and a subframe number (Here only uses this as an example, and may also include a slot number Etc.)
  • the frame number is frame 1
  • the subframe number is subframe 1
  • the corresponding absolute time is T1
  • the relative time of the target network device at the same absolute time is frame 1
  • the subframe number is subframe 2
  • the target The time format sent by the network device to the UE is frame 1
  • the subframe number is subframe 2.
  • the time information sent by the target network device to the UE is in another form that can represent the second time, for example, only the low bit of the frame number corresponding to frame 1 is used to indicate frame 1, where the low bit refers to the frame number.
  • the lower bits of the binary bits (such as frame number 20, corresponding to 10-bit binary is 0000010100, the lower bit refers to 10100), can also be referred to as the second most important bit of the frame number.
  • the absolute time in the present application may be GPS time or coordinated universal time (UTC).
  • the method includes the following steps:
  • the target network device obtains the first time information corresponding to the data unit.
  • the first time T1 is based on the timing of the source network device, specifically frame 1 and subframe 1.
  • the target network device may obtain the first time information from the source network device, or may obtain the first time information from the previous protocol layer.
  • the target network device also receives the data unit from the source network device.
  • the target network device determines the second time information corresponding to the data unit.
  • the second time refers to the timing of the target network device, and the second time is specifically frame 1 and subframe 2.
  • the target network device sends the second time information to the terminal device.
  • the target network device also sends the data unit to the terminal device.
  • the terminal device determines the delay information according to the information about the second time and the information about the third time when the data unit is received.
  • the third time T2 takes the timing of the target network device as a reference, T2 is frame 1, subframe 3.
  • the terminal device sends the delay information to the target network device.
  • the above S501 to S505 are downlink switching transmission processes.
  • the process of sending data units with the following terminal device may be independent.
  • the terminal device obtains the first time information corresponding to the data unit and determines the second time corresponding to the data unit Information.
  • the first time T3 at which the UE sends the data unit to the source network device, taking the timing of the source network device as a reference then T3 is frame 2 and subframe 1.
  • the UE determines that the first time T3 taking the timing of the target network device as a reference is frame 2 and subframe 2 according to the information of the first time and the timing deviation.
  • the terminal device sends the second time information to the target network device.
  • the target network device determines the delay information according to the second time information and the third time information of the received data unit.
  • T4 is frame 2
  • the source network device transfers the switched data unit to the target network device in the form of SDAP PDU/PDCP SDU.
  • the source network device carries relative time information (the first time information) in the extension header of the GTP-U, and the target network device carries the second time information in the packet header of the PDCP PDU sent to the UE.
  • FIG. 6 it is a schematic diagram of the packet format carrying time information in the packet header of the PDCP PDU, where LMI indicates whether the PDCP PDU carries time information, and the time information (time stamp) is located in the third word of the PDCP PDU
  • the section and the fourth byte can also be located in other bytes, which is not limited here.
  • the relative time here may be identified by at least one of frame number, subframe number, and slot number, or may be a time offset relative to a reference time (such as relative to a frame number , Subframe number, time slot number time offset).
  • the target network device determines the second time information according to the following manner: the target network device determines the time information carried by the GTP-U and the timing deviation of the two cells.
  • the first time information carried by the extension header of the GTP-U corresponds to the source network device timing as T_source
  • the corresponding time is Absolute time T1.
  • the absolute time T1 corresponds to T_target with reference to the timing of the target network device
  • the time information corresponding to the data unit sent by the target network device to the UE is the relative time corresponding to T_target with reference to the timing of the target network device.
  • the time information of the extension header of the GTP-U is represented by the frame number and subframe number.
  • the frame number is frame 1
  • the subframe number is subframe 1
  • the corresponding absolute time is T1
  • the same time is on the target network
  • the relative time of the device is frame 1
  • the subframe number is subframe 2
  • the time format sent by the target network device to the UE is frame 1
  • the subframe number is subframe 2.
  • the time information sent by the target network device to the UE is in another form that can represent the second time, for example, only the lower bits of the frame number corresponding to frame 1 are used to indicate frame 1.
  • the scenario targeted by this implementation is that when the source network device and the target network device send data units to the terminal device, the source network device carries the first-time information in the extension header of the GTP-U, and the target network device sends the data to the UE.
  • the header of the PDCP PDU carries the second-time information.
  • the first time information is relative time information with reference to the timing of the source network device, and the target network device converts the first time information into relative time with reference to the timing of the target network device, so that the terminal device can uniformly adopt the current serving cell Calculate the time delay corresponding to the data unit regularly, reducing the processing complexity of the terminal device.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP PDU/PDCP SDU.
  • the source network device carries absolute time information (the absolute time corresponding to the first time information) in the extension header of the GTP-U, and the target network device carries the second time in the header of the SDAP PDU sent to the UE information.
  • the absolute time information carried in the GTP-U is the moment when the source network device receives the data packet in the data unit, for example, the moment when the SDAP layer of the source network device receives the SDAP SDU, or the PDCP of the source network device The moment the layer receives the PDCP SDU.
  • the target network device determines the second time information according to the following manner: the target network device determines according to the absolute time in the GTP-U. For example, the absolute time carried in GTP-U is T_absolute, then the target network device sets T_absolute as its relative time according to the relationship between the absolute time and relative time set by itself. For example, as shown in FIG. 4, where T_absolute is T1, the target network device knows that the relative time of T1 absolute time corresponding to the target network device is frame 1, subframe 2, so that the target network device knows to set the relative time to frame 1, subframe 2.
  • the time information sent by the target network device to the UE is in another form that can represent the second time, for example, only the lower bits of the frame number corresponding to frame 1 are used to indicate frame 1.
  • the scenario targeted by this implementation is that when the source network device and the target network device send data units to the terminal device, the source network device carries absolute time information in the extension header of the GTP-U, and the target network device converts the absolute time information to Taking the relative time of the target network device as a reference, the target network device carries the second time information in the SDAP PDU header sent to the UE, so that the terminal device can uniformly use the current serving cell's timing to calculate the data unit The corresponding delay reduces the processing complexity of the terminal equipment.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP PDU/PDCP SDU.
  • the source network device carries absolute time information (absolute time corresponding to the first time information) in the extension header of the GTP-U, and the target network device carries the second time in the header of the PDCP PDU sent to the UE information.
  • the absolute time carried in the GTP-U is the time when the source network device receives the data unit, for example, the time when the PDCP layer of the source network device receives the PDCP SDU, or the SDAP layer of the source network device receives the SDAP SDU Moment.
  • the target network device determines the second time information according to the following manner: the target network device determines the second time information according to the absolute time in the GTP-U.
  • the absolute time carried in GTP-U is T_absolute
  • the target network device sets T_absolute as its relative time according to the relationship between the absolute time and relative time set by itself.
  • T_absolute is T1
  • the target network device knows that the relative time of T1 absolute time in the target network device corresponds to frame 1, subframe 2, so that the target network device knows to set the relative time to frame 1, subframe 2.
  • the time information sent by the target network device to the UE is in another form that can represent the second time, for example, only the lower bits of the frame number corresponding to frame 1 are used to indicate frame 1.
  • the scenario targeted by this implementation is that when the source network device and the target network device send data units to the terminal device, the source network device carries absolute time information in the extension header of the GTP-U, and the target network device sends the PDCP PDU to the UE
  • the header of the message carries the second time information, and the target network device converts the absolute time information to a relative time referenced to the target network device timing, so that the terminal device can uniformly use the current serving cell timing to calculate the data unit.
  • the corresponding delay reduces the processing complexity of the terminal equipment.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP PDU/PDCP SDU.
  • the source network device carries relative time information (the first time information) in the SDAP PDU header, and the target network device carries the second time information in the SDAP PDU header sent to the UE.
  • the time that the target network device carries when sending data to the UE is T1 in absolute time, and the time information sent by the target network device to the UE is set according to the time T1.
  • the time reference point is time reference point 2
  • the relative time is Relative time 2.
  • the target network device knows the information of the absolute time reference point sent by the source network device (that is, the target network device knows the time domain position of the absolute time reference point of the source network device), for example, the time domain position refers to the frame number and subframe number Location information, so that the target network device knows which time reference point the data unit corresponds to based on the timing deviation, thereby knowing the corresponding absolute time T1, and then the target network device obtains the absolute time corresponding to the target network device according to the absolute time T1 Reference point 2 and relative time 2, and then carry the relative time 2 in the SDAP PDU header to the UE.
  • the target network device knows the information of the absolute time reference point sent by the source network device (that is, the target network device knows the time domain position of the absolute time reference point of the source network device), for example, the time domain position refers to the frame number and subframe number Location information, so that the target network device knows which time reference point the data unit corresponds to based on the timing deviation, thereby knowing the corresponding absolute time T1, and then the target network
  • a broadcast message is sent every 100 frames, the absolute time corresponding to the moment of the broadcast message is delivered in the broadcast message, and the relative time carried in the data unit is relative to the time carried by a previous broadcast message Offset.
  • the target network device knows the time point corresponding to a certain absolute time T1, and knows the corresponding relationship between the absolute time and the time reference point, thereby knowing the relative time.
  • T1 is 15:23:11 and 11 ms on November 5, 2018.
  • the target network device knows its reference point for each absolute time, for example, a reference point every 20 minutes, the first time reference point is 15:23 on November 5, 2018, and the second time reference point is 2018 At 15:43 on November 5, ... so that the target network device knows that the time reference point at T1 is reference point 1, and the relative time is the difference between the absolute time corresponding to T1 and the reference point 1, that is, the relative time is 11 11 milliseconds.
  • the scenario targeted by this implementation is that when the source network device and the target network device send data units to the terminal device, the source network device carries the first-time information in the SDAP PDU packet header, and the target network device sends the The header of the SDAP PDU carries the second-time information.
  • the first time information is relative time information with reference to the timing of the source network device, and the target network device converts the first time information into relative time with reference to the timing of the target network device, so that the terminal device can uniformly adopt the current serving cell Calculate the time delay corresponding to the data unit regularly, reducing the processing complexity of the terminal device.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP PDU/PDCP SDU.
  • the source network device carries relative time information (the first time information) in the extension header of the GTP-U, and the target network device carries the second time information in the PDCP PDU packet header sent to the UE.
  • the target network device determines the second time information according to the following manner: the target network device determines according to the relative time information carried by the GTP-U and the timing deviation of the two cells.
  • the time corresponding to the time information carried by the extension header of the GTP-U is T1
  • the absolute time reference point corresponding to T1 is reference point 1
  • relative The time is relative time 1 (relative time information carried in the extension header of the GTP-U transferred from the source network device to the target network device)
  • the time that the target network device carries when sending data to the UE is T1 in absolute time
  • the time information sent by the target network device to the UE is set according to the time T1.
  • the time reference point is time reference point 2
  • the relative time is relative time 2.
  • the target network device knows the information of the absolute time reference point sent by the source network device (that is, the target network device knows the time domain position of the absolute time reference point of the source network device), for example, the time domain position refers to the frame number and subframe number Location information. In this way, the target network device knows which time reference point corresponding to the data unit according to the timing deviation, so as to know the corresponding absolute time T1, and then the target network device obtains the absolute time reference point 2 and the relative time corresponding to the target network device according to the absolute time T1. Time 2, and then carry the relative time 2 in the PDCP PDU header to the UE.
  • the scenario targeted by this implementation is that when the source network device and the target network device send data units to the terminal device, the source network device carries the first-time information in the extension header of the GTP-U, and the target network device sends the data to the UE.
  • the header of the PDCP PDU carries the second-time information.
  • the first time information is relative time information with reference to the timing of the source network device, and the target network device converts the first time information into relative time with reference to the timing of the target network device, so that the terminal device can uniformly adopt the current serving cell Calculate the time delay corresponding to the data unit regularly, reducing the processing complexity of the terminal device.
  • the source network device transfers the switched data unit to the target network device in SDAP PDU/PDCP SDU.
  • the source network device carries absolute time and relative time information, or absolute time information in the extension header of the GTP-U, and the target network device carries the modified time information in the header of the SDAP PDU sent to the UE.
  • the target network device determines the second time information according to the following manner: the target network device sets the absolute time and the relative time (second time) sent by the target network device to the UE according to the absolute time carried in the GTP-U.
  • the absolute time corresponding to the absolute time and relative time information carried in GTP-U is T1 or the absolute time information carried in GTP-U is absolute time T1
  • the target network device sets the absolute time sent to the UE according to the absolute time T1 Time and relative time.
  • the time reference corresponding to the absolute time T1 is the absolute time reference 2
  • the relative time is the relative time 2.
  • the second time information sent by the target network device to the UE carries the relative time 2.
  • the scenario targeted by this implementation is that when the source network device and the target network device send data units to the terminal device, the source network device carries the first-time information in the extension header of the GTP-U, and the target network device sends the data to the UE.
  • the header of the SDAP PDU carries the second-time information.
  • the first time information is absolute time information and relative time information, or absolute time information.
  • the target network device converts the first time information into a relative time referenced to the target network device timing, so that the terminal device can uniformly adopt the current serving cell To calculate the delay corresponding to the data unit, reducing the processing complexity of the terminal device.
  • the source network device transfers the switched data unit to the target network device through SDAP PDU/PDCP SDU.
  • the source network device carries absolute time and relative time information, or absolute time information in the extension header of the GTP-U, and the target network device carries the second time information in the PDCP PDU header sent to the UE.
  • the target network device determines the second time information according to the following manner: the target network device sets the absolute time and the relative time sent by the target network device to the UE according to the absolute time carried in the GTP-U.
  • the absolute time corresponding to the absolute time and relative time information carried in GTP-U is T1 or the absolute time information carried in GTP-U is absolute time T1
  • the target network device sets the absolute time sent to the UE according to the absolute time T1 Time and relative time.
  • the time reference corresponding to the absolute time T1 is the absolute time reference 2
  • the relative time is the relative time 2.
  • the scenario targeted by this implementation is that when the source network device and the target network device send data units to the terminal device, the source network device carries the first-time information in the extension header of the GTP-U, and the target network device sends the data to the UE.
  • the header of the PDCP PDU carries the second-time information.
  • the first time information is absolute time information and relative time information, or absolute time information.
  • the target network device converts the first time information into a relative time referenced to the target network device timing, so that the terminal device can uniformly adopt the current serving cell To calculate the delay corresponding to the data unit, reducing the processing complexity of the terminal device.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP SDU.
  • the source network device carries relative time information (the first time information) in the extension header of the GTP-U, and the target network device carries the second time information in the header of the SDAP PDU sent to the UE.
  • the time information carried in the GTP-U is the time information that the source network device receives the data unit, specifically the time when the SDAP layer of the source network device receives the SDAP SDU.
  • the target network device determines the second time information according to the following manner: the target network device determines the first time information carried by the SDAP PDU and the timing deviation of the two cells/two network devices.
  • the first time information carried in the SDAP PDU is referenced to the source network device timing, corresponding to T_source
  • the corresponding time is absolute time. T1.
  • the absolute time T1 corresponds to T_target with reference to the timing of the target network device
  • the time information corresponding to the data unit sent by the target network device to the UE is the relative time corresponding to T_target with reference to the timing of the target network device.
  • the time information of the SDAP PDU transferred from the source network device is represented by the frame number and subframe number, for example, the frame number is frame 1, and the subframe number is subframe 1, the corresponding absolute time is T1, and the relative time of the target network device at the same time is frame 1, the subframe number is subframe 2, so the time format sent by the target network device to the UE is frame 1, and the subframe number is subframe 2.
  • the scenario targeted by this implementation is that when the source network device and the target network device send data units to the terminal device, the source network device carries the first-time information in the extension header of the GTP-U, and the target network device sends the data to the UE.
  • the header of the SDAP PDU carries the second-time information.
  • the first time information is relative time information with reference to the timing of the source network device, and the target network device converts the first time information into relative time with reference to the timing of the target network device, so that the terminal device can uniformly adopt the current serving cell Calculate the time delay corresponding to the data unit regularly, reducing the processing complexity of the terminal device.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP SDU.
  • the source network device carries relative time information (the first time information) in the extension header of the GTP-U, and the target network device carries the second time information in the PDCP PDU packet header sent to the UE.
  • the time information carried in the GTP-U is the time information that the source network device receives the data unit, specifically the moment when the SDAP layer of the source network device receives the SDAP SDU, or the PDCP layer of the source network device receives the PDCP SDU moment.
  • the target network device determines the second time information according to the following manner: the target network device determines the time information carried by the GTP-U and the timing deviation of the two cells.
  • the first time information carried by the SDAP PDU corresponds to the source network device timing as reference T_source
  • the corresponding time as the absolute time T1.
  • the absolute time T1 corresponds to T_target with reference to the timing of the target network device
  • the time information corresponding to the data unit sent by the target network device to the UE is the relative time corresponding to T_target with reference to the timing of the target network device.
  • the target network device determines the time information carried by the GTP-U and the timing deviation of the two cells.
  • the first time information carried by the SDAP PDU corresponds to the source network device timing as reference T_source
  • the time information of the SDAP PDU transferred from the source network device is represented by the frame number and subframe number, for example, the frame number is frame 1, and the subframe number is subframe 1, the corresponding absolute time is T1, and the relative time of the target network device at the same time is frame 1, the subframe number is subframe 2, so the time format sent by the target network device to the UE is frame 1, and the subframe number is subframe 2.
  • the scenario targeted by this implementation is that when the source network device and the target network device send data units to the terminal device, the source network device carries the first-time information in the extension header of the GTP-U, and the target network device sends the data to the UE.
  • the header of the PDCP PDU carries the second-time information.
  • the first time information is relative time information with reference to the timing of the source network device, and the target network device converts the first time information into relative time with reference to the timing of the target network device, so that the terminal device can uniformly adopt the current serving cell Calculate the time delay corresponding to the data unit regularly, reducing the processing complexity of the terminal device.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP SDU.
  • the source network device carries absolute time information (absolute time corresponding to the first time) in the extension header of the GTP-U, and the target network device carries the second time information in the header of the SDAP PDU sent to the UE.
  • the absolute time information carried in the GTP-U is the time when the source network device receives the data unit, specifically the time when the SDAP layer of the source network device receives the SDAP SDU.
  • the target network device determines the second time information according to the following manner: the target network device determines according to the absolute time in GTP-U. For example, the absolute time carried in GTP-U is T_absolute, then the target network device sets T_absolute as its relative time according to the relationship between the absolute time and relative time set by itself. For example, as shown in Figure 5, T_absolute is T1, then the target network device knows that the relative time of T1 absolute time in the target network device corresponds to frame 1, subframe 2, so that the target network device knows to set the relative time to frame 1, subframe 2. .
  • the scenario targeted by this implementation is that when the source network device and the target network device send data units to the terminal device, the source network device carries the first-time information in the extension header of the GTP-U, and the target network device sends the data to the UE.
  • the header of the SDAP PDU carries the second-time information.
  • the first time information is absolute time information
  • the target network device converts the first time information into a relative time referenced to the target network device timing, so that the terminal device can uniformly adopt the current serving cell timing to calculate the time corresponding to the data unit Delay, reducing the processing complexity of the terminal equipment.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP SDU.
  • the source network device carries absolute time information (absolute time corresponding to the first time) in the extension header of the GTP-U, and the target network device carries the second time information in the packet header of the PDCP PDU sent to the UE.
  • the absolute time carried in the GTP-U is the moment when the source network device receives the data unit, specifically the moment when the SDAP layer of the source network device receives the SDAP SDU or the PDCP layer of the source network device receives the PDCP SDU time.
  • the target network device determines the second time information according to the following manner: the target network device modifies according to the absolute time in GTP-U. For example, the absolute time carried in GTP-U is T_absolute, then the target network device sets T_absolute as its relative time according to the relationship between the absolute time and relative time set by itself. For example, as shown in Figure 4, T_absolute is T1, then the target network device knows that the relative time of T1 absolute time in the target network device corresponds to frame 1, subframe 2, so that the target network device knows to set the relative time to frame 1, subframe 2. .
  • the scenario targeted by this implementation is that when the source network device and the target network device send data units to the terminal device, the source network device carries the first-time information in the extension header of the GTP-U, and the target network device sends the data to the UE.
  • the header of the PDCP PDU carries the second-time information.
  • the first time information is absolute time information
  • the target network device converts the first time information into a relative time referenced to the target network device timing, so that the terminal device can uniformly adopt the current serving cell timing to calculate the time corresponding to the data unit Delay, reducing the processing complexity of the terminal equipment.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP SDU.
  • the source network device carries relative time information (the first time information) in the extension header of the GTP-U, and the target network device carries the second time information in the header of the SDAP PDU sent to the UE.
  • the time information carried in the GTP-U is the time information when the source network device receives the data packet, specifically the time when the SDAP layer of the source network device receives the SDAP SDU.
  • the time that the target network device carries when sending data to the UE is T1 in absolute time, and the time information sent by the target network device to the UE is set according to the time T1.
  • the time reference point is time reference point 2
  • the relative time is Relative time 2.
  • the target network device knows the information of the absolute time reference point sent by the source network device (that is, the target network device knows the time domain position of the absolute time reference point of the source network device), for example, the time domain position refers to the frame number and subframe number Location information, so that the target network device knows which time reference point the data unit corresponds to based on the timing deviation, so as to know the corresponding absolute time T1, and then the target network device obtains the absolute time reference corresponding to the target network device according to the absolute time T1 Point 2 and relative time 2, and then carry the relative time 2 in the SDAP PDU header to the UE.
  • the target network device knows the information of the absolute time reference point sent by the source network device (that is, the target network device knows the time domain position of the absolute time reference point of the source network device), for example, the time domain position refers to the frame number and subframe number Location information, so that the target network device knows which time reference point the data unit corresponds to based on the timing deviation, so as to know the corresponding absolute time T1, and then the
  • the scenario targeted by this implementation is that when the source network device and the target network device send data units to the terminal device, the source network device carries the first-time information in the extension header of the GTP-U, and the target network device sends the data to the UE.
  • the header of the SDAP PDU carries the second-time information.
  • the first time information is relative time information with reference to the timing of the source network device, and the target network device converts the first time information into relative time with reference to the timing of the target network device, so that the terminal device can uniformly adopt the current serving cell Calculate the time delay corresponding to the data unit regularly, reducing the processing complexity of the terminal device.
  • the source network device transfers the switched data unit to the target network device through SDAP SDU.
  • the source network device carries relative time information (the first time information) in the extension header of the GTP-U, and the target network device carries the second time information in the PDCP PDU packet header sent to the UE.
  • the target network device determines the second time information according to the following manner: the target network device determines according to the relative time information carried by the GTP-U and the timing deviation of the two cells.
  • the time corresponding to the time information carried by the extension header of the GTP-U is T1
  • T1 corresponds to
  • the absolute time reference point is reference point 1
  • the relative time is relative time 1 (relative time information carried in the extension header of the GTP-U transferred from the source network device to the target network device), when the target network device sends data to the UE
  • the carried time is T1 in absolute time, and the time information sent by the target network device to the UE is set according to the time T1.
  • the time reference point is time reference point 2
  • the relative time is relative time 2.
  • the target network device knows the information of the absolute time reference point sent by the source network device (that is, the target network device knows the time domain position of the absolute time reference point of the source network device), for example, the time domain position refers to the frame number and subframe number Location information. In this way, the target network device knows which time reference point corresponding to the data unit according to the timing deviation, so as to know the corresponding absolute time T1, and then the target network device obtains the absolute time reference point 2 and the relative time corresponding to the target network device according to the absolute time T1. Time 2, and then carry the relative time 2 in the PDCP PDU header to the UE.
  • the scenario targeted by this implementation is that when the source network device and the target network device send data units to the terminal device, the source network device carries the first-time information in the extension header of the GTP-U, and the target network device sends the data to the UE.
  • the header of the PDCP PDU carries the second-time information.
  • the first time information is relative time information with reference to the timing of the source network device, and the target network device converts the first time information into relative time with reference to the timing of the target network device, so that the terminal device can uniformly adopt the current serving cell Calculate the time delay corresponding to the data unit regularly, reducing the processing complexity of the terminal device.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP SDU.
  • the source network device carries absolute time and relative time information, or absolute time information in the extension header of the GTP-U, and the target network device carries the modified time information in the header of the SDAP PDU sent to the UE.
  • the target network device determines the second time information according to the following manner: the target network device sets the absolute time and the relative time (second time) sent by the target network device to the UE according to the absolute time (first time) carried in the GTP-U. For example, if the absolute time carried in the GTP-U is T1, the target network device sets the absolute time and relative time sent to the UE according to the absolute time T1. For example, in the target network device, the time reference corresponding to the absolute time T1 is the absolute time reference 2, and the relative time is the relative time 2.
  • the scenario targeted by this implementation is that when the source network device and the target network device send data units to the terminal device, the source network device carries the first-time information in the extension header of the GTP-U, and the target network device sends the data to the UE.
  • the header of the SDAP PDU carries the second-time information.
  • the first time information is absolute time information and relative time information, or absolute time information.
  • the target network device converts the first time information into absolute time and relative time with reference to the target network device timing, so that the terminal device can uniformly adopt the The time delay of the current serving cell is used to calculate the delay corresponding to the data unit, which reduces the processing complexity of the terminal device.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP SDU.
  • the source network device carries the absolute time and relative time information, or absolute time information in the extension header of the GTP-U, and the target network device carries the second time information in the packet header of the PDCP PDU sent to the UE.
  • the target network device determines the second time information according to the following manner: the target network device sets the absolute time and the relative time sent by the target network device to the UE according to the absolute time carried in the GTP-U. For example, if the absolute time carried in the GTP-U is T1, the target network device sets the absolute time and relative time sent to the UE according to the absolute time T1. For example, in the target network device, the time reference corresponding to the absolute time T1 is the absolute time reference 2, and the relative time is the relative time 2.
  • the scenario targeted by this implementation is that when the source network device and the target network device send data units to the terminal device, the source network device carries the first-time information in the extension header of the GTP-U, and the target network device sends the data to the UE.
  • the header of the PDCP PDU carries the second-time information.
  • the first time information is absolute time information and relative time information, or absolute time information.
  • the target network device converts the first time information into relative time and absolute time with reference to the target network device timing, so that the terminal device can uniformly adopt the The time delay of the current serving cell is used to calculate the delay corresponding to the data unit, which reduces the processing complexity of the terminal device.
  • the UE serves as the sending end device, and the UE determines the second time information.
  • the UE sends to the target network device a data unit that has not been correctly received by the source network device or a data unit for which time information has been set according to the format of the source network device, the UE considers the waiting time of these data units on the UE side.
  • the UE converts to the second time information of the target network device according to the time deviation between the source network device and the target network device, and the first time information corresponding to the data unit.
  • it includes the following two implementation methods: A17 and A18:
  • the UE converts the original time (first time) to the relative time (second time) of the target network device based on the first time information corresponding to the data unit and the timing deviation between the source network device and the target network device In the form of.
  • the first time and the second time are expressed in the form of relative time, such as frame number, subframe number, etc.
  • the original time information is the frame number is frame 1
  • the subframe number is subframe 1
  • the corresponding time is T1
  • the relative time of the target network device at the same time is frame 1
  • the subframe number is subframe 2.
  • the implementation mode A17 is adopted, and the scenario targeted by this implementation mode is that when the terminal device sends a data unit to the source network device and the target network device, the terminal device sends the second time information to the target network device.
  • the first time information is relative time information with reference to the timing of the source network device.
  • the terminal device converts the first time information into relative time with reference to the timing of the target network device, so that the target network device can uniformly adopt the current service cell. Calculate the time delay corresponding to the data unit regularly, reducing the processing complexity of the target network device.
  • the UE converts the original time (first time) to the relative time (second time) of the target network device based on the first time information corresponding to the data unit and the timing deviation between the source network device and the target network device In the form of.
  • the first time and the second time are expressed in the form of absolute time and relative time.
  • the absolute time corresponding to a frame is used as a reference point
  • the relative time is the time offset relative to the frame. For example, as shown in FIG.
  • the reference point corresponding to the source network device at the first time is the absolute time delivered with the frame number of frame 1
  • the relative time in the first time is the time offset T2 relative to frame 1
  • the reference point corresponding to the target network device at the moment corresponding to the first time is the absolute time delivered by the frame number frame 2.
  • the relative time in the second time is the time offset T3 relative to frame 1.
  • the implementation mode A18 is adopted, and the scenario targeted by this implementation mode is that when the terminal device sends a data unit to the source network device and the target network device, the terminal device sends the second time information to the target network device.
  • the first time information is relative time information and absolute time information with reference to the timing of the source network device.
  • the terminal device converts the first time information into relative time and absolute time with reference to the timing of the target network device, so that the target network device can
  • the timing of the current serving cell is used uniformly to calculate the time delay corresponding to the data unit, which reduces the processing complexity of the target network device.
  • FIG. 9 is a schematic flowchart of another communication method according to an embodiment of the present application. The method includes the following steps:
  • the target network device obtains the first time information corresponding to the data unit.
  • the target network device may receive the first time information corresponding to the data unit from the source network device.
  • the target network device may also obtain the first time information corresponding to the data unit from the PDCP layer.
  • the source network device sends the received data unit to the target network device.
  • the target network device receives the data unit and obtains the first time information carried by the data unit.
  • the first time indicates the first time when the source network device receives the data unit.
  • the first time is based on the timing of the source network device.
  • the source network device sends the received data unit to the target network device, and the source network device sends the first time information corresponding to the data unit to the target network device.
  • the target network device receives the data unit and obtains the first time information corresponding to the data unit.
  • the first time indicates the first time when the source network device receives the data unit. The first time is based on the timing of the source network device, or the first time is the absolute time when the source network device receives the data unit.
  • the source network device sends the received data unit to the target network device, and the source network device sends the first time information corresponding to the data unit to the target network device.
  • the target network device receives the data unit and obtains the first time information corresponding to the data unit.
  • the first time instructs the UE to send the data unit at the first moment corresponding to the source network device, or instructs the UE's wireless protocol layer (such as SDAP or PDCP layer) to receive the data unit from the upper layer (such as the application layer or IP layer) Time, or the moment when the UE's wireless protocol layer (such as SDAP or PDCP layer) sends the data unit to the next layer, or the UE's wireless protocol layer (such as SDAP or PDCP layer) is received from the upper layer (such as the application layer or IP layer) Any time between the time when the data unit and the UE's wireless protocol layer (such as SDAP or PDCP layer) send the data unit to the next layer.
  • the first time is based on the timing of the source network device.
  • the target network device determines the second time information corresponding to the data unit.
  • the target network device needs to send the data packet received from the source network device to the core network device. In order to accurately obtain the delay of receiving the data packet from the UE, the target network device needs to determine the time when the target network device receives the data packet from the UE , The second time.
  • the UE may switch between different cells or different network devices. Therefore, the timing deviation includes at least one of the following: the timing deviation between the target network device and the source network device, and the timing deviation between the target network device and the source network device.
  • the target network device may determine the second according to the relationship between the information about the first time and the absolute time and relative time of the target network device in the target network device Time information.
  • the second time is the time when the source network device receives the data unit. The second time is based on the timing of the target network device.
  • the target network device may also determine the information of the second time according to the information of the first time, where the second time is an absolute time corresponding to the time when the source network device receives the data unit.
  • the target network device uses the second time and the moment when the data packet corresponding to the data unit is submitted to the core network device.
  • the difference between these two moments is the delay of the data packet.
  • the time when the data unit is sent refers to the time when the target network device sends the data packet in the data unit to the core network, or the SDAP layer of the target network device sends the data packet in the data unit to The moment of the PDCP layer, or the moment when the PDCP layer of the target network device sends the data packet in the data unit to the SDAP layer.
  • the method further includes: sending the delay information to a network management system.
  • the network management system monitors the transmission efficiency of the network according to the requirements of the operator.
  • the target network device sends delay information to the network management system, so that the operator can optimize the network based on the delay information.
  • the first time information is time information with reference to the timing of the source network device
  • the target network device converts the first time information to the target network
  • the device timing is the referenced second time information, so that the terminal device can uniformly adopt the timing of the current serving cell, which reduces the processing complexity of the terminal device.
  • the target network device may compensate for the time required to transfer from the source network device to the target base station, or unify the form of the first time and the second time, and calculate Delay. It includes the following implementations A19 ⁇ A25. It should be noted that the uplink transfer will only be performed under lossless handover.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP PDU or PDCP SDU.
  • the source network device carries relative time information in the SDAP PDU header, and the target network device calculates the delay.
  • the target network device calculates the delay according to the following method: the target network device compensates based on the time information carried by the SDAP PDU and the timing deviation of the two cells.
  • the time corresponding to the time information carried by the SDAP PDU is T1
  • T1 corresponds to the frame in which the relative time representation of the source network device is the source network device Number frame 1
  • subframe number is subframe 1
  • the target network device calculates the time delay, first converts the frame number of the source network device frame1 corresponding to the time T1 according to the timing deviation of the two cells
  • the subframe number is subframe1 to T1 corresponds to the frame number of the target network device frame1, subframe number subframe2
  • the target network device calculates the correspondence according to the frame number of the target network device frame1, subframe number subframe2 and the frame number of the target network device frame 1, subframe number is
  • the time information of the SDAP PDU is that the corresponding frame number is frame 1, the subframe number is subframe 1, the corresponding time is T1, and the relative time of the target network device at the same time is frame 1, the subframe number is subframe 2, and The time when the target network device SDAP layer submits the data packet to the upper layer is frame 3, and the subframe number is subframe 3. Then the delay is (frame 3-frame 1)*10ms+(subframe 3-subfram 2)*1ms.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP PDU or PDCP SDU.
  • the source network device carries the first time in the SDAP PDU packet header.
  • Information the first time is a relative time
  • the target network device determines the information of the second time according to the information of the first time and the timing deviation, so that the delay of the current serving cell can be used as a reference to calculate the delay.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP PDU or PDCP SDU.
  • the source network device carries relative time information in the extension header of the GTP-U, and the target network device calculates the delay.
  • the target network device calculates the delay according to the following manner: the target network device compensates based on the time information carried by the GTP-U and the timing deviation of the two cells.
  • the time corresponding to the time information carried by GTP-U is T1
  • T1 corresponds to the relative time representation of the source network device as the source network device Frame number frame1
  • subframe number is subframe1
  • the target network device calculates the time delay, first converts the frame number of the source network device frame1 corresponding to time T1
  • the subframe number is subframe1 according to the timing deviation of the two cells.
  • T1 corresponds to the frame number of the target network device frame1, subframe number subframe2, the target network device calculates the correspondence according to the frame number of the target network device frame1, subframe number subframe2 and the frame number of the target network device frame 1, the subframe number is subframe3 Delay.
  • the time information of SDAP PDU is that the corresponding frame number is frame 1, the subframe number is subframe 1, the corresponding time is T1, and the relative time of the target network device at the same time is frame 1, the subframe number is subframe 2, and The time when the target network device SDAP layer submits the data packet to the upper layer is frame 3, and the subframe number is subframe 3.
  • the delay is (frame 3-frame 1)*10ms+(subframe 3-subframe 2)*1ms.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP PDU or PDCP SDU.
  • the source network device carries the first time in the extension header of the GTP-U Information, the first time is a relative time, and the target network device determines the information of the second time according to the information of the first time and the timing deviation, so that the delay of the current serving cell can be used as a reference to calculate the delay.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP PDU or PDCP SDU.
  • the source network device carries the absolute time and the delay information of the data unit in the extension header of the GTP-U, and the target network device calculates the delay.
  • the absolute time is the moment when the source network device receives the data packet, specifically the moment when the PDCP layer of the source network device receives the PDCP SDU.
  • the delay information is a delay calculated by the source network device to send the data packet from the UE to the source network device.
  • the target network device calculates the delay according to the following method: the target network device uses the absolute time carried by the GTP-U, the delay information of the data unit, and the time required for the data packet corresponding to the data unit to be submitted to the upper layer in the target network device Calculate the corresponding delay.
  • the absolute time for the PDCP layer of the target network device to submit the packet to the upper layer is T2
  • the absolute time carried by the GTP-U is T1
  • the delay of the data unit sent from the UE to the source network device to receive the packet is Delay_source
  • the total delay of the packet is: T2-T1+Delay_source.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP PDU or PDCP SDU.
  • the source network device carries the first time in the extension header of the GTP-U Information, the first time is an absolute time, and the target network device determines the information of the second time according to the information of the first time and the timing deviation, so that the timing of the current serving cell can be uniformly used to calculate the delay.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP PDU or PDCP SDU.
  • the source network device carries relative time information in the SDAP PDU header, and the target network device calculates the delay.
  • the target network device calculates the delay according to the following method: the target network device compensates based on the relative time information carried by the SDAP PDU and the timing deviation of the two cells.
  • the time corresponding to the time information carried by the extension header of the GTP-U is T1
  • the absolute time reference point corresponding to T1 is reference point 1
  • the target network device can calculate the absolute time reference point 2 and relative time corresponding to T1 at the target network device 2.
  • the target network device knows the information of the absolute time reference point sent by the source network device (that is, the target network device knows the time domain position of the absolute time reference point of the source network device), for example, the time domain position refers to the frame number and subframe number Location information. In this way, the target network device knows which time reference point the packet corresponds to based on the timing deviation, thereby knowing the corresponding absolute time T1, and then the target network device obtains the absolute time reference point 2 and the relative time corresponding to the target network device according to the absolute time T1. 2.
  • the absolute time for submitting the packet to the upper layer according to the SDAP layer of the target network device is T2 (absolute time reference point 2 and relative time 3 corresponding to the target network device) and absolute time T1 (absolute time corresponding to the target network device Reference point 2 and relative time 2) Calculate the delay.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP PDU or PDCP SDU.
  • the source network device carries the first time in the SDAP PDU packet header Information, the first time is a relative time, and the target network device determines the information of the second time according to the information of the first time and the timing deviation, so that the delay of the current serving cell can be used as a reference to calculate the delay.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP PDU or PDCP SDU.
  • the source network device carries the absolute time in the extension header of the GTP-U, and the relative time in the SDAP PDU.
  • the target network device calculates the delay according to the following method: based on the absolute time carried in the GTP-U and the relative time carried in the SDAP PDU. For example, the time when the target network device submits the SDAP SDU to the upper layer is T2, the time corresponding to the absolute time carried in the GTP-U and the relative time carried in the SDAP PDU is T1, and the delay is T2-T1.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP PDU or PDCP SDU.
  • the source network device carries the first time in the extension header of the GTP-U Information, the first time is an absolute time, and the target network device determines the information of the second time according to the information of the first time and the timing deviation, so that the timing of the current serving cell can be uniformly used to calculate the delay.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP PDU or PDCP SDU.
  • the source network device carries absolute time information, or absolute time and relative time information in the extension header of GTP-U.
  • the target network device calculates the delay according to the following method: the delay is calculated according to the absolute time carried by the GTP-U. For example, assuming that the absolute time of the PDCP layer of the target network device submitting the data packet to the upper layer is T2, and the time corresponding to the absolute time information carried by the GTP-U is T1, the delay is T2-T1.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP PDU or PDCP SDU.
  • the source network device carries the first time in the SDAP PDU packet header Information, the first time is absolute time, or absolute time and relative time, the target network device determines the second time information according to the first time information and timing deviation, so that the current serving cell timing can be used as a reference Calculate the delay.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP PDU or PDCP SDU.
  • the source network device carries the absolute time and the delay information of the data packet in the extension header of the GTP-U.
  • the absolute time is the moment when the source network device receives the data unit, specifically the moment when the PDCP layer of the source network device receives the PDCP SDU.
  • the delay information is a delay calculated by the source network device to send the data packet from the terminal to the source network device.
  • the target network device calculates the delay according to the following method: calculate the corresponding delay based on the absolute time carried by the GTP-U + the delay information of the packet + the time required for the packet to be submitted to the upper layer in the target network device.
  • the absolute time when the PDCP layer of the target network device submits the packet to the upper layer is T2, and the absolute time that GTP-U carries is T1.
  • the delay of the packet at the source network device is Delay_source, then the total delay of the packet is: T2-T1+Delay_source.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP PDU or PDCP SDU.
  • the source network device carries the first time in the extension header of the GTP-U Information, the first time is an absolute time, and the target network device determines the information of the second time according to the information of the first time and the timing deviation, so that the timing of the current serving cell can be uniformly used to calculate the delay.
  • FIG. 10 is a schematic flowchart of another communication method according to an embodiment of the present application. The method includes the following steps:
  • the receiving device obtains the first time information corresponding to the data unit.
  • This method can be applied to scenarios such as downlink handover transmission or UE sending data units.
  • the sending end device sends a data unit to the receiving end device, and correspondingly, the receiving end device receives the data unit.
  • the first time refers to the timing of the source network device.
  • the receiving end device acquiring the first time information corresponding to the data unit includes: the receiving end device receives the first time information corresponding to the data unit from the sending end device.
  • the receiving end device is a terminal device
  • the sending end device is a target network device
  • the method further includes: the receiving end device receives a first indication from the sending end device, the first The indication is used to indicate that the data unit is a data unit transferred from the source network device to the target network device.
  • the source network device needs to transfer the downlink data received from the core network and not yet correctly received by the UE To the target network device.
  • a first time message is sent at the same time.
  • the time corresponding to the first time is the same as the first time corresponding to when the sending end device is the target network device in S201, and the first time refers to the timing of the source network device.
  • the target network device receives the data unit sent by the source network device and sends the data unit to the terminal device.
  • the first instruction is also sent to the terminal device.
  • the first indication is used to indicate that the data unit is a data unit that is transferred from the source network device to the target network device.
  • the first indication may also be included in the data unit, and the first indication may also be included in the header of the SDAP or PDCP PDU corresponding to the data unit.
  • the first indication may also be a control data unit, the data units before the control data unit are all data units transferred from the source network device to the target network device, and none of the data units after the control packet are from The data unit of the source network device is transferred to the target network device.
  • the receiving end device acquiring the first time information corresponding to the data unit includes: the receiving end device acquiring the first time information corresponding to the data unit from the PDCP layer.
  • the PDCP layer of the receiving device obtains the data unit from the target network device.
  • the first time is the time when the other protocol stack layer of the receiving device obtains the data unit from the PDCP layer during subsequent processing.
  • the UE sends a data unit
  • the UE records the time when the data unit is sent to the source network device, which is the first time.
  • the first time corresponds to the first time when the sending end device in S201 is the terminal device, with the timing of the source network device as a reference.
  • the terminal device sends the first time information corresponding to the data unit to the target network device.
  • the first time is based on the timing of the source network device.
  • the terminal device also sends a first indication to the target network device.
  • the first indication is used to indicate that the data unit is a data unit sent by the terminal device, or a data unit sent by the terminal device during a handover process, or a first time corresponding to the data unit Is based on the timing of the source network device.
  • the first indication may also be carried in the data unit.
  • the first time information is carried in the data unit.
  • the first indication may also be included in the header of the SDAP or PDCP PDU corresponding to the data unit.
  • the first indication may also be a control data unit, the data units before the control data unit are all data units transferred from the source network device to the target network device, and none of the data units after the control data unit are The data unit transferred from the source network device to the target network device, or the control data unit represents the end of the data unit transferred from the source network device to the target network device.
  • the receiving device determines, based on the first time information, timing deviation, and second time information that the receiving device receives the data unit, the receiving device obtains the data unit’s Delay information.
  • the terminal device receives the data unit and the first indication from the target network device.
  • the terminal device simultaneously receives the first time information corresponding to the data unit from the target network device. If the first instruction indicates that the data unit is a data unit transferred from the source network device to the target network device, the terminal device receives the second data unit according to the first time information, timing deviation, and the terminal device For the time information, calculate the delay information that the terminal device receives the data unit.
  • the timing deviation includes at least one of the following: a timing deviation between the target network device and the source network device, and a timing deviation between the target network device and the source network device.
  • the second time refers to the moment when the UE successfully receives the data unit, or the wireless protocol layer of the UE (such as the SDAP or PDCP layer) submits the data packet of the data unit to the upper layer (such as the application layer or the IP layer) ), or the moment when the UE's wireless protocol layer (such as the PDCP layer) forwards the data packet of the data unit to the next wireless protocol layer (such as the SDAP layer), or the UE's wireless protocol layer (such as the SDAP or PDCP layer) Any time between the moment of the data unit and the moment when the data packet of the data unit is submitted to the upper layer.
  • the wireless protocol layer of the UE such as the SDAP or PDCP layer
  • the method further includes the following steps:
  • the receiving end device sends the delay information to the target network device.
  • the terminal device After calculating the delay, the terminal device sends the delay information to the target network device. After receiving the delay information, the target network device can know the delay of the downlink transmission of the target network device to the terminal device.
  • the second time is based on the timing of the target network device.
  • the target network device receives the data unit and the first indication from the terminal device. Receiving the first time information corresponding to the data unit.
  • the target network device may determine the delay information of the received data unit according to the first time information, timing deviation, and second time information of the received data unit.
  • the timing deviation includes at least one of the following: a timing deviation between the target network device and the source network device, and a timing deviation between the target network device and the source network device.
  • the second time refers to the moment when the target network device successfully receives the data unit, or the wireless protocol layer of the target network device (such as the SDAP or PDCP layer) submits the data packet of the data unit to the upper layer (such as the application Layer or IP layer or core network), or the time when the wireless protocol layer of the target network device (such as the PDCP layer) transfers the data packet of the data unit to a wireless protocol layer (such as the SDAP layer), or the wireless of the target network device Any time between the time when the protocol layer (such as SDAP or PDCP layer) receives the data unit and the time when the data packet of the data unit is submitted to the upper layer.
  • the upper layer such as the application Layer or IP layer or core network
  • the wireless protocol layer of the target network device such as the PDCP layer
  • the target network device may also convert the first time information and the second time information to other unified time forms to calculate the delay of the data unit, for example, to convert the time to the source network device as a reference, or Absolute time etc.
  • the method further includes: sending the delay information to a network management system.
  • the network management system monitors the transmission efficiency of the network according to the requirements of the operator.
  • the target network device sends delay information to the network management system, so that the operator can optimize the network based on the delay information.
  • the first time information is time information with reference to the timing of the source network device, and the receiving end device converts the first time information to the target network
  • the device timing is the information of the referenced time, so that the timing of the current serving cell can be uniformly used to calculate the delay.
  • the terminal device serves as the receiving device, and the terminal device modifies the time information.
  • the terminal device modifies the time information.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP PDU/PDCP SDU.
  • the source network device transfers the SDAP PDU/PDCP SDU.
  • the SDAP PDU carries relative time information (time information is the frame number, subframe number, etc.), and the target network device carries the time information in the header of the SDAP PDU sent to the UE.
  • the UE calculates the delay according to the following method: The UE converts the time information carried in the SDAP PDU according to the time deviation between the source network device and the target network device.
  • the UE finds that the data unit is a data unit transferred from the source network device to the target network device, then the UE knows that the time information carried therein is based on the source network device, and then the UE can use the source network device and the target network device Calculate the relative time of the target network device corresponding to the carried time information.
  • the time information of the SDAP PDU is that the corresponding frame number is frame 1, the subframe number is subframe 1, and the corresponding time is T1.
  • the UE can know the relative time of the target network device at the same time as frame 1 based on the time deviation of the two cells
  • the subframe number is subframe 2.
  • the UE converts the time when the packet is submitted to the upper layer according to the SDAP layer and the time information carried in the SDAP PDU into the relative time of the target network device as the delay of the packet.
  • the UE may also convert the time information carried in the SDAP PDU and the time when the UE submits the packet to the upper layer to other unified forms to calculate the delay of the packet, such as the time converted to the source network device for reference, Or absolute time.
  • the receiving end device determines the flow of the second time information.
  • the method includes the following steps:
  • the target network device obtains the first time information corresponding to the data unit.
  • the first time T1 is based on the timing of the source network device, specifically frame 1 and subframe 1.
  • the target network device may obtain the first time information from the source network device, or may obtain the first time information from the previous protocol layer.
  • the target network device also receives the data unit from the source network device.
  • the target network device sends the first time information to the terminal device.
  • the target network device also sends the data unit to the terminal device.
  • the terminal device determines the second time information corresponding to the data unit, and determines the delay information according to the second time information and the third time information of the received data unit.
  • the second time refers to the timing of the target network device, and the second time is specifically frame 1 and subframe 2.
  • the third time T2 refers to the timing of the target network device, and T2 is frame 1 and subframe 3.
  • the terminal device sends the delay information to the target network device.
  • the above S1101 to S1104 are downlink switching transmission processes.
  • the process of sending data units with the following terminal device may be independent.
  • the terminal device obtains the first time information corresponding to the data unit.
  • T3 is frame 2 and subframe 1.
  • the terminal device sends the first time information to the target network device.
  • the target network device determines the second time information, and determines the delay information according to the second time information and the third time information of the received data unit.
  • the UE determines that the first time T3 taking the timing of the target network device as a reference is frame 2 and subframe 2 according to the information of the first time and the timing deviation.
  • T4 is frame 2
  • the source network device transfers the switched data unit to the target network device in the form of SDAP PDU/PDCP SDU.
  • the source network device transfers the SDAP PDU and carries time information in the extension header of the GTP-U (time information is the frame number, subframe number, etc.), and the target network device adds the time information carried in the GTP-U to the PDCP PDU in.
  • the time information carried in the GTP-U is the time information when the source network device receives the data packet.
  • the UE calculates the delay according to the following method: the UE converts the time information carried in the PDCP PDU according to the time deviation between the source network device and the target network device.
  • the UE finds that the data unit is a data unit transferred from the source network device to the target network device, then the UE knows that the time information carried therein is based on the source network device, and then the UE can use the source network device and the target network device Calculate the relative time of the target network device corresponding to the carried time information.
  • the time information of the PDCP PDU is corresponding to the frame number frame 1, the subframe number is subframe 1, the corresponding time is T1, the UE can know the relative time of the target network device at the same time is frame 1 according to the time deviation of the two cells
  • the subframe number is subframe 2.
  • the UE converts the time when the packet is submitted to the upper layer according to the PDCP layer and the time information carried in the PDCP PDU into the relative time of the target network device as the delay of the packet.
  • the UE may also convert the time information carried in the PDCP PDU and the time when the UE submits the packet to the upper layer to other unified forms to calculate the delay of the packet, such as the time converted to the source network device for reference, Or absolute time.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP PDU/PDCP SDU.
  • the source network device transfers the SDAP PDU, and the SDAP PDU carries a time offset equivalent to an absolute time in the source network device, that is, relative time information, and the target network device adds the relative time information carried in the GTP-U to the SDAP Carried in PDU.
  • the time information carried in the GTP-U represents the moment when the source network device receives the data packet, specifically the moment when the SDAP layer of the source network device receives the SDAP SDU.
  • the UE calculates the delay according to the following method: The UE converts the time information carried in the SDAP PDU according to the time deviation between the source network device and the target network device.
  • the UE finds that the data unit is a data unit transferred from the source network device to the target network device then the UE knows that the time information carried therein is based on the source network device, and then the UE can use the source network device and the target network device Calculate the relative time of the target network device corresponding to the carried time information. For example, if the UE finds that the data unit is a data unit transferred from the source network device to the target network device, it can know the absolute time T1 of the source network device. The relative time in the SDAP PDU is based on the absolute time T1 of the source network device. , So the start time of this data unit is: the relative time carried by T1+SDAP PDU. The time when the UE SDAP layer submits the data unit to the upper layer is the absolute time T2 of the target network device, and the delay of the packet is T2-(T1+SDAP PDU relative time).
  • the source network device transfers the switched data unit to the target network device in the form of SDAP PDU/PDCP SDU.
  • the source network device transfers the SDAP PDU, and carries the time offset equivalent to an absolute time in the source network device, that is, relative time information, in the extension header of the GTP-U, and the relative time carried by the target network device in the GTP-U
  • the information is added to the PDCP and carried in the PDU.
  • the absolute time carried in the GTP-U is the moment when the source network device receives the data packet, specifically the moment when the PDCP layer of the source network device receives the PDCP SDU.
  • the UE calculates the delay according to the following method: the UE converts the time information carried in the PDCP PDU according to the time deviation between the source network device and the target network device. For example, if the UE finds that the data unit is a data unit transferred from the source network device to the target network device, then the UE knows that the time information carried therein is based on the source network device, and then the UE can use the source network device and the target network device Calculate the relative time of the target network device corresponding to the carried time information. For example, if the UE finds that the data unit is a data unit transferred from the source network device to the target network device, it can know the absolute time T1 of the source network device.
  • the relative time in the PDCP PDU is based on the absolute time T1 of the source network device. , So the start time of this data unit is: the relative time carried by T1+PDCP PDU.
  • the delay of the data unit is T2-(T1+PDCP relative time carried by the PDU).
  • Implementation method B5. The source network device transfers the switched data unit to the target network device in the form of SDAP SDU.
  • the source network device carries relative time information in the extension header of the GTP-U (time information is frame number, subframe number, etc.), and the target network device carries time information in the header of the SDAP PDU sent to the UE.
  • the UE calculates the delay according to the following method: same as B1.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP SDU.
  • the source network device transfers the SDAP SDU and carries time information in the extension header of the GTP-U (time information is the frame number, subframe number, etc.), and the target network device adds the time information carried in the GTP-U to the PDCP PDU in.
  • the time information carried in the GTP-U is the time information when the source network device receives the data packet.
  • the UE calculates the delay according to the following method: the same as B2.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP SDU.
  • the source network device transfers the SDAP SDU and carries the time offset equivalent to an absolute time in the source network device, that is, relative time information, in the extension header of the GTP-U, and the relative time carried by the target network device in the GTP-U
  • the information is added to the SDAP PDU.
  • the time information carried in the GTP-U represents the moment when the source network device receives the data packet, specifically the moment when the SDAP layer of the source network device receives the SDAP SDU.
  • the UE calculates the delay according to the following method: same as B3.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP SDU.
  • the source network device transfers the SDAP SDU and carries the time offset equivalent to an absolute time in the source network device, that is, relative time information, in the extension header of the GTP-U, and the relative time carried by the target network device in the GTP-U
  • the information is added to the PDCP and carried in the PDU.
  • the absolute time carried in the GTP-U is the moment when the source network device receives the data packet.
  • the UE calculates the delay according to the following method: same as B4.
  • the UE sends a data unit that is not correctly received by the source network device to the target network device.
  • the target network device calculates the delay information. Specifically, it includes the following two implementation methods of B9 and B10:
  • Implementation method B9. The UE sends a data unit that is not correctly received by the source network device to the target network device.
  • the target network device calculates the delay based on the time deviation between the source network device and the target network device. For example, if the target network device finds that the data unit is a data unit transferred from the source network device to the target network device, then the target network device knows that the time information carried therein is based on the source network device, then the target network device may be based on the source network The time deviation between the device and the target network device is used to calculate the relative time of the target network device corresponding to the carried time information.
  • the time information of the SDAP PDU corresponds to the frame number of frame 1, subframe number of subframe 1, and the corresponding time is T1.
  • the target network device can be based on the time deviation between the source network device and the target network device It is known that the relative time of the target network device at the same moment is frame 1, and the subframe number is subframe 2. Then, the target network device converts the time when the data unit is submitted to the upper layer according to the SDAP layer and the time information carried in the SDAP PDU into the relative time of the target network device as the time delay of the data unit.
  • Implementation method B10 The UE sends a data unit that is not correctly received by the source network device to the target network device.
  • the target network device calculates the delay based on the time deviation between the source network device and the target network device. For example, if the target network device finds that the data unit is a data unit transferred from the source network device to the target network device, then the target network device knows that the time information carried therein is based on the source network device, then the target network device may be based on the source network The time deviation between the device and the target network device is used to calculate the relative time of the target network device corresponding to the carried time information.
  • the target network device when the target network device finds that the data unit is a data unit transferred from the source network device to the target network device, it can learn that the time information carried in the SDAP PDU corresponds to the absolute time reference point 1, and then according to The time information carried in the SDAP PDU knows the absolute time T1 corresponding to the time information.
  • the target network device knows the information of the absolute time reference point sent by the source network device (that is, the target network device knows the time domain position of the absolute time reference point of the source network device), for example, the time domain position refers to the frame number and subframe number Location information.
  • the target network device knows which time reference point corresponding to the data unit according to the timing deviation, so as to know the corresponding absolute time T1, and then the target network device obtains the absolute time reference point 2 and the relative time corresponding to the target network device according to the absolute time T1 Time 2, the absolute time after which the data unit is submitted to the upper layer according to the PDCP layer of the target network device is T2 (absolute time reference point 2 and relative time 3 corresponding to the target network device) and absolute time T1 (corresponding to the target network device Absolute time reference point 2 and relative time 2) Calculate the delay.
  • the source network device needs to transfer the out-of-order data units received from the UE to the target network device, so that the target network device calculates the delay corresponding to these out-of-order data units. It should be noted that the uplink transfer will only be performed under lossless handover.
  • One method is to use the method in the previous A17 ⁇ A23.
  • Another method is to use B11 as follows.
  • the source network device transfers the switched data unit to the target network device in the form of SDAP PDU or PDCP SDU.
  • the source network device carries time information in the SDAP PDU packet header.
  • the time information may be relative time (frame number, subframe number, etc.) referenced to the source network device timing, or it may be an absolute value in the source network device.
  • the time radio frame is the reference time offset.
  • the target network device calculates the delay according to the time deviation between the source network device and the target network device: same as B9 ⁇ B10.
  • This application also proposes how to obtain the correspondence between the absolute time and the wireless frame number or/and subframe number in the CU-DU architecture, so that the CU sets the time information at the SDAP/PDCP layer.
  • the time information carries a time offset that takes a certain absolute time as a reference.
  • the base station will notify the UE of the absolute time corresponding to a radio frame number or subframe number, such as a broadcast message or a radio resource control (RRC) message to notify the UE.
  • RRC radio resource control
  • the DU is responsible for configuring the relationship between the absolute time in the broadcast message and the radio frame number or/and subframe number to the UE.
  • the DU sends a message to the CU.
  • the message carries the correspondence between absolute time and frame number or/and subframe number, the scheduling of each system information block (system information block, SIB), such as the scheduling list of each SIB and the window of system messages At least one of size, period of system information, etc.
  • SIB system information block
  • the CU can know the radio frame number or/and subframe number corresponding to each moment, so that the CU knows how to set the time information corresponding to the data unit in the SDAP/PDCP layer.
  • the CU is responsible for configuring the relationship between the absolute time in the broadcast message and the radio frame number or/and subframe number to the UE.
  • the CU sends a message to the DU.
  • the message carries the correspondence between absolute time and frame number/and subframe number.
  • SIB system information block
  • the DU can know how to schedule various system messages.
  • the CU is responsible for configuring the relationship between the absolute time and the radio frame number or/and subframe number in the broadcast message to the UE, and the DU sends a message to the CU.
  • the message carries at least the absolute time and the frame number or/and subframe number.
  • SIB system information block
  • the above information may be exchanged between CU-UP and DU, or the above information may be exchanged between CU-CP and DU, and then the above information may be exchanged between CU-CP and CU-UP.
  • the above information refers to the corresponding relationship between the absolute time and the frame number/and subframe number, and the scheduling arrangement of each system information block.
  • FIG. 12 is a schematic flowchart of another communication method according to an embodiment of the present application.
  • the time information corresponding to the data unit of the network device side and the UE is a relative time corresponding to a certain absolute time point as a reference.
  • S1201 The network device notifies the UE of the current absolute time.
  • the network device may broadcast the current absolute time in the broadcast message.
  • the broadcast message carries the absolute time corresponding to the system frame number (SFN) boundary on or after the end boundary of the broadcast message window corresponding to the broadcast message.
  • SFN system frame number
  • the above absolute time may carry an offset time relative to a fixed absolute time.
  • this fixed time is 00:00:00 on January 1, 1900, the solar calendar (midnight between December 31, 1899 and January 1, 1900), or 00:00:00 on January 6, 1980 (Global Positioning System (Global Positioning System, GPS) time).
  • the absolute time may be coordinated universal time (UTC) or GPS time.
  • UTC Universal Time
  • the sending end device sends the data unit and the first time information.
  • the sending device may be a UE, and the receiving device may be a network device; in downlink transmission, the sending device may be a network device, and the receiving device may be a UE.
  • the process shown in FIG. 12 is based on downlink transmission.
  • the first time information corresponds to the data unit.
  • the first time information sent may be an offset from a certain absolute time.
  • the network device will notify (via broadcast message or RRC message) the configuration of the UE's time reference point: taking a certain absolute time as a starting point and taking every certain time as a period, that is, notifying this starting point and/or this period. Or the agreement stipulates these contents.
  • the first time information carried is the time offset relative to the starting point of the current cycle. For example, at an absolute time (for example, Gregorian calendar January 1, 1900 00:00:00, that is, midnight before December 31, 1899 and January 1, 1900, or January 6, 1980, the solar calendar 00:00:00) is the starting point, and every 1s is a cycle.
  • the time reference point is 10:11:15, November 7, 2018.
  • the first time information is 20 milliseconds.
  • the CU-CP needs to notify the CU-UP of the configuration of these time reference points, that is, taking a certain absolute time as a starting point and taking every certain time as a cycle, that is, notifying this starting point and/or this cycle.
  • the first time information carried may be a part of the current absolute time, for example, it only carries the millisecond and microsecond content of the current absolute time.
  • the absolute time when the sending device sends a certain data unit is 10:11:15, 20 milliseconds, 10 microseconds on November 7, 2018, the time information it carries is 20 milliseconds, 10 microseconds.
  • the network device will notify (via broadcast message or RRC message) which part of the current absolute time the UE time information is. It should be noted that in this embodiment, it is necessary to additionally solve the problem of how the CU-UP knows these configurations in the CU-CP and CU-UP scenarios. For example, the CU-CP needs to inform the CU-UP which part of the current absolute time the time information carries, for example, it only carries the millisecond and microsecond content of the current absolute time.
  • the receiving end device After receiving the data unit and the first time information, calculates a delay according to the first time information and the second time information of the received data unit.
  • the receiving end calculates the delay of the data unit, which is the end time minus the start time.
  • the start time is the first time information corresponding to the data unit
  • the end time is the time when the receiving device receives the data unit, or the receiving device submits the data unit to other layers (such as the PDCP layer of the receiving device Submit to the SDAP layer, or the PDCP layer of the receiving device to the IP layer or core network).
  • the receiving end device determines that the period reference points corresponding to the starting point and the ending point are different, the receiving end device needs to compensate the corresponding period when calculating the time delay The difference in reference points.
  • the period reference point T1 corresponding to the start point is before the period reference point T2 corresponding to the end point
  • the first time information carried is the offset Offset1 relative to the period reference point T1
  • the time corresponding to the start point is T1+Offset1
  • the end time is the offset from the cycle reference point T2 is Offset 2
  • the time corresponding to the end point is T2+Offset 2
  • the receiving end device needs to compensate for the difference between the two cycle reference points, and the immediate delay is: T2+Offset 2 – (T1+Offset 1).
  • the first time information carried may be part of the current absolute time (for example, milliseconds and microseconds), and the receiving end device can determine the absolute time of the starting point. For example, if a part of the absolute time corresponding to the current end point (for example, milliseconds and microseconds) is smaller than the starting point, the receiving device knows that the first time information carried is corresponding to 1 second earlier than the second unit in the current absolute time. Milliseconds and microseconds.
  • the network device explicitly takes absolute time as a reference, and the sending end device notifies the receiving end device of the time information of the sending data unit.
  • the time information may be an absolute time or a part of the absolute time.
  • the end device can accurately calculate the time delay between the sending data unit of the sending end device and the receiving data unit of the receiving end device according to the time information corresponding to the data unit and the time information of receiving the data unit.
  • Embodiments of the present application also provide a method for not performing delay measurement on the data unit transferred from the source network device to the target network device during the handover process.
  • One method is: when the target network device or target cell sends the downlink data unit transferred from the source network device or source cell to the UE, when the target network device or target cell sends the data unit, it does not carry time information or indicate that it is not necessary Perform delay measurement.
  • the target network device or target cell receives the uplink data unit transferred from the source network device or source cell, the target network device or target cell does not calculate the delay of these uplink data units.
  • the UE transmits the PDCP SDU that has been associated with the PDCP SN before the handover by the target network device or target cell, the UE does not carry time information or indicates that no delay measurement is required when transmitting these data units.
  • the target network device carries a timer in the handover command to the UE.
  • the timer defines that the UE does not receive any uplink data after the handover command or PDCP reestablishment. Carrying time information or indicating that the data unit does not require delay measurement or calculation of the delay of the downlink data unit.
  • Embodiments of the present application also provide a method for measuring the delay of the data unit transferred from the source network device to the target network device during the handover process without considering the delay caused by the handover.
  • One method is: when the target network device or target cell sends the downlink data unit transferred from the source network device or source cell to the UE, when the target network device or target cell sends the data unit, the time carried is the target network device Or the moment when the target cell receives the data unit.
  • the UE has associated the PDCP SDU of the PDCP before the handover of the target network device or target cell, the time it carries is the moment when the UE is ready to send these data units in the target network device or target cell.
  • an embodiment of the present application further provides a communication device 1300 that can be applied to the above-mentioned communication method shown in FIG. 2.
  • the communication device 1300 may be the network device 100 shown in FIG. 1-1, or may be a component (such as a chip) applied to the network device 100; in a scenario where a terminal device sends a data unit
  • the communication device 1300 may be the terminal device 200 shown in FIG. 1-1, or may be a component (for example, a chip) applied to the terminal device 200.
  • the communication device 1300 includes: a processing unit 131 and a communication unit 132; wherein:
  • the processing unit 131 is configured to obtain information about the first time corresponding to the data unit, and the first time uses the timing of the source network device as a reference;
  • the processing unit 131 is further configured to determine information about a second time corresponding to the data unit, and the second time uses the timing of the target network device as a reference;
  • the communication unit 132 is configured to send the second time information to the receiving device.
  • the communication unit 132 is further configured to receive time delay information from the receiving end device, where the time delay information is the information of the receiving end device according to the second time and the The device at the receiving end obtains the third time information of the data unit by calculation.
  • the communication unit 132 is further configured to receive the first time information corresponding to the data unit from the source network device.
  • the processing unit 131 is further configured to acquire the first time information corresponding to the data unit from the packet data aggregation protocol PDCP layer.
  • processing unit 131 and communication unit 132 can be directly obtained by directly referring to the related description of the network device in the method embodiment shown in FIG. 2 above, and details are not described here.
  • an embodiment of the present application further provides a communication device 1400, which can be applied to the above communication method shown in FIG. 9.
  • the communication device 1400 may be the network device 100 shown in FIG. 1-1, or may be a component (such as a chip) applied to the network device 100; in a scenario where a terminal device sends a data unit
  • the communication device 1400 may be the terminal device 200 shown in FIG. 1-1, or may be a component (such as a chip) applied to the terminal device 200.
  • the communication device 1400 includes: a processing unit 141, and optionally, a communication unit 142; wherein:
  • the processing unit 141 is configured to obtain information about the first time corresponding to the data unit, and the first time uses the timing of the source network device as a reference;
  • the processing unit 141 is further configured to determine information about a second time corresponding to the data unit, and the second time uses the timing of the target network device as a reference;
  • the processing unit 141 is further configured to determine the time delay information of the data unit according to the second time information and the time when the data unit is sent.
  • the communication unit 142 is configured to receive the first time information corresponding to the data unit from the source network device.
  • the processing unit 141 is further configured to obtain the first time information corresponding to the data unit from the packet data aggregation protocol PDCP layer.
  • the communication unit 142 is further configured to send the delay information to the network management system.
  • processing unit 141 and communication unit 142 can be directly obtained by directly referring to the related description of the network device in the method embodiment shown in FIG. 9 above, and details are not described here.
  • an embodiment of the present application further provides a communication device 1500 that can be applied to the above-mentioned communication method shown in FIG. 10.
  • the communication device 1500 may be the network device 100 shown in FIG. 1-1, or may be a component (such as a chip) applied to the network device 100; in a scenario where a terminal device sends a data unit
  • the communication device 1500 may be the terminal device 200 shown in FIG. 1-1, or may be a component (for example, a chip) applied to the terminal device 200.
  • the communication device 1500 includes: a processing unit 151, and optionally, a communication unit 152; wherein:
  • the processing unit 151 is configured to obtain information about the first time corresponding to the data unit, and the first time uses the timing of the source network device as a reference;
  • the processing unit 151 is further configured to determine, based on the information of the first time, timing deviation, and information of the second time when the receiving device obtains the data unit, the receiving device obtains the data unit Delay information.
  • the communication unit 152 is configured to receive the first time information corresponding to the data unit from the source device.
  • the communication unit 152 is further configured to receive a first indication from the sending end device, where the first indication is used to indicate that the data unit is transferred from the source network device to the The data unit of the target network device.
  • the communication unit 152 is further configured to send the delay information to the sending device.
  • the communication unit 152 is further configured to send the delay information to the network management system.
  • processing unit 151 and communication unit 152 can be directly obtained by directly referring to the related description of the network device in the method embodiment shown in FIG. 10 above, which will not be repeated here.
  • An embodiment of the present application further provides a communication device, which is used to execute the above communication method.
  • a communication device which is used to execute the above communication method.
  • Some or all of the above communication methods may be implemented by hardware or software.
  • the communication device may be a chip or an integrated circuit during specific implementation.
  • the communication device when part or all of the communication method in the above embodiment is implemented by software, the communication device includes: a memory for storing a program; a processor for executing the program stored in the memory, when the program is executed, The communication device can implement the communication method provided in the above embodiment.
  • the above memory may be a physically independent unit, or may be integrated with the processor.
  • the communication device may also include only the processor.
  • the memory for storing the program is located outside the communication device, and the processor is connected to the memory through a circuit/wire to read and execute the program stored in the memory.
  • the processor may be a central processing unit (CPU), a network processor (NP), or a combination of CPU and NP.
  • CPU central processing unit
  • NP network processor
  • the processor may further include a hardware chip.
  • the hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD) or a combination thereof.
  • the PLD may be a complex programmable logic device (complex programmable logic device, CPLD), a field programmable gate array (field-programmable gate array, FPGA), a general array logic (generic array logic, GAL), or any combination thereof.
  • the memory may include volatile memory (volatile memory), such as random access memory (random-access memory, RAM); the memory may also include non-volatile memory (non-volatile memory), such as flash memory (flash memory) , Hard disk drive (HDD) or solid-state drive (SSD); the memory may also include a combination of the above types of memory.
  • volatile memory volatile memory
  • RAM random access memory
  • non-volatile memory non-volatile memory
  • flash memory flash memory
  • HDD Hard disk drive
  • SSD solid-state drive
  • the memory may also include a combination of the above types of memory.
  • the disclosed system, device, and method may be implemented in other ways.
  • the division of the unit is only a logical function division, and there may be other divisions in actual implementation.
  • multiple units or components may be combined or integrated into another system, or some features may be ignored, or not carried out.
  • the displayed or discussed mutual coupling, direct coupling, or communication connection may be indirect coupling or communication connection through some interfaces, devices, or units, and may be in electrical, mechanical, or other forms.
  • the units described as separate components may or may not be physically separate, and the components displayed as units may or may not be physical units, that is, they may be located in one place or may be distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
  • the computer program product includes one or more computer instructions.
  • the computer may be a general-purpose computer, a dedicated computer, a computer network, or other programmable devices.
  • the computer instructions may be stored in a computer-readable storage medium or transmitted through the computer-readable storage medium.
  • the computer instructions can be transferred from a website, computer, server or data center via wired (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (such as infrared, wireless, microwave, etc.) to another A website site, computer, server or data center for transmission.
  • the computer-readable storage medium may be any available medium that can be accessed by a computer or a data storage device including a server, a data center, and the like integrated with one or more available media.
  • the available media may be read-only memory (ROM), or random access memory (RAM), or magnetic media, such as floppy disks, hard disks, magnetic tapes, magnetic disks, or optical media, such as, Digital versatile disc (DVD), or semiconductor media, such as solid state disk (SSD), etc.

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Abstract

本申请公开了一种通信方法及装置。该方法包括：发送端设备获取数据单元对应的第一时间的信息，所述第一时间以源网络设备的定时作为参考；所述发送端设备确定所述数据单元对应的第二时间的信息，所述第二时间以所述目标网络设备的定时作为参考；所述发送端设备向接收端设备发送所述第二时间的信息。还公开了对应的装置。采用本申请的方案，在切换传输过程中，第一时间信息为以源网络设备定时为参考的时间信息，发送端设备把该第一时间的信息转换为以目标网络设备定时为参考的第二时间的信息，从而接收端设备可以统一采用当前服务小区的定时，降低了接收端设备的处理复杂度。

Description

通信方法及装置
本申请要求于2018年12月7日提交中国国家知识产权局、申请号为201811496817.7、发明名称为“通信方法及装置”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，尤其涉及一种通信方法及装置。
背景技术
随着通信需求的发展，越来越多的业务需要保证低时延的性能。例如，超可靠低时延通信(ultra reliable low latency commnications，URLLC)业务要求时延在0.5ms之内。因此，为了保证业务的性能，运营商需要知道当前网络的时延性能。
在切换场景下，源基站需要把从核心网接收的且还没被终端设备正确接收的下行数据单元和从终端设备接收的乱序的上行数据单元转移到目标基站。乱序是指在源基站从终端正确接收到的数据单元之前的一些数据单元并没有被源基站正确接收(例如，收到了packet 2/3，但还没收到packet1)。为了获取数据单元在基站和终端设备之间的传输时延，在发送端对应的协议数据单元(protocol data unit，PDU)中携带一个时间信息。例如，在包数据汇聚协议(packet data convergence protocol，PDCP)PDU或者服务数据适配协议(service data adaptation protocol，SDAP)PDU中携带时间信息。
发明内容
本申请提供一种通信方法及装置，以准确地确定数据单元切换传输过程中的时间信息。
第一方面，提供了一种通信方法，包括：发送端设备获取数据单元对应的第一时间的信息，所述第一时间以源网络设备的定时作为参考；所述发送端设备确定所述数据单元对应的第二时间的信息，所述第二时间以所述目标网络设备的定时作为参考；以及所述发送端设备向接收端设备发送所述第二时间的信息。
在该方面中，在下行切换传输过程或者终端设备发送数据单元的过程中，第一时间信息为以源网络设备定时为参考的时间信息，发送端设备把该时间信息转换为以目标网络设备定时为参考的时间信息，从而接收端设备可以统一采用当前服务小区的定时，降低了接收端设备的处理复杂度。
在一种可能的实现方式中，所述第二时间是根据所述第一时间和定时偏差确定的，所述定时偏差包括所述目标网络设备与所述源网络设备的定时偏差。
在该实现方式中，切换还可以在小区之间进行，或者在主基站与辅基站之间进行，则定时偏差还可以是目标小区与源小区的定时偏差，或者主基站与辅基站之间的定时偏差。
在另一种可能的实现方式中，所述发送端设备为目标网络设备，所述接收端设备为终端设备，所述方法还包括：所述发送端设备接收来自所述接收端设备的时延信息，其中， 所述时延信息为所述接收端设备根据所述第二时间的信息与所述接收端设备获取所述数据单元的第三时间的信息计算得到的。
在该实现方式中，接收端设备在确定数据单元对应的时间信息的定时参考后，可以根据该第二时间的信息以及获取该数据单元的第三时间的信息，计算接收与发送之间的时延信息。发送端设备接收该时延信息，可以了解接收与发送之间的时延。
在又一种可能的实现方式中，所述发送端设备获取数据单元对应的第一时间的信息，包括：所述发送端设备从所述源网络设备接收所述数据单元对应的第一时间的信息。
在该实现方式中，发送端设备可以接收源网络设备发送的数据单元，同时接收数据单元对应的第一时间的信息。
在又一种可能的实现方式中，所述第一时间的信息携带在服务数据适配协议SDAP协议数据单元PDU的报头中，或携带在通用分组无线服务用户面隧道协议GTP-U报文对应的扩展报头中。
在该实现方式中，第一时间的信息具体携带在数据单元的SDAP PDU的报头中，或者携带在发送数据单元的GTP-U报文的报头中。
在又一种可能的实现方式中，所述发送端设备获取数据单元对应的第一时间的信息，包括：所述发送端设备从包数据汇聚协议PDCP层获取所述数据单元对应的第一时间的信息。
在该实现方式中，发送端设备还可以从自身的PDCP层获取数据单元对应的第一时间的信息，该第一时间为发送端设备的PDCP层从源网络设备接收到数据单元的时间。
在又一种可能的实现方式中，所述第一时间的信息包括以下一种或两种时间信息：相对时间信息、绝对时间信息。
在该实现方式中，第一时间的信息为以源网络设备定时为参考的相对时间信息，发送端设备把第一时间信息转化为以目标网络设备定时为参考的相对时间，从而接收端设备可以统一采用以当前服务小区的定时来计算数据单元对应的时延，降低了接收端设备的处理复杂度。或者第一时间的信息为绝对时间信息，发送端设备把该绝对时间信息转换为以目标网络设备定时为参考的相对时间，从而接收端设备可以统一采用以当前服务小区的定时来计算数据单元对应的时延，降低了接收端设备的处理复杂度。
第二方面，提供了另一种通信方法，包括：目标网络设备获取数据单元对应的第一时间的信息，所述第一时间以源网络设备的定时作为参考；所述目标网络设备确定所述数据单元对应的第二时间的信息，所述第二时间以所述目标网络设备的定时作为参考；以及所述目标网络设备根据所述第二时间的信息和发送所述数据单元的时刻，确定所述数据单元的时延信息。
在该方面中，在上行切换传输过程中，第一时间信息为以源网络设备定时为参考的时间信息，目标网络设备把该时间信息转换为以目标网络设备定时为参考的时间信息，从而目标网络设备可以统一采用以当前服务小区的定时来计算数据单元对应的时延，降低了目标网络设备的处理复杂度。
在一种可能的实现方式中，所述第二时间是根据所述第一时间和定时偏差确定的，所述定时偏差包括所述目标网络设备与所述源网络设备的定时偏差。
在另一种可能的实现方式中，所述目标网络设备获取数据单元对应的第一时间的信息，包括：所述目标网络设备从所述源网络设备接收所述数据单元对应的第一时间的信息。
在又一种可能的实现方式中，所述第一时间的信息携带在服务数据适配协议SDAP协议数据单元PDU的报头中，或携带在通用分组无线服务用户面隧道协议GTP-U报文对应的扩展报头中。
在又一种可能的实现方式中，所述目标网络设备获取数据单元对应的第一时间的信息，包括：所述目标网络设备从包数据汇聚协议PDCP层获取所述数据单元对应的第一时间的信息。
在又一种可能的实现方式中，所述第一时间的信息包括以下一种或两种时间信息：相对时间信息、绝对时间信息。
在又一种可能的实现方式中，所述方法还包括：所述目标网络设备向网管系统发送所述时延信息。
在该实现方式中，网管系统获取该时延信息，可以对数据传输过程进一步的优化。
第三方面，提供了又一种通信方法，包括：接收端设备获取数据单元对应的第一时间的信息，所述第一时间以源网络设备的定时作为参考；以及所述接收端设备根据所述第一时间的信息、定时偏差、以及所述接收端设备获取所述数据单元的第二时间的信息，确定所述接收端设备获取所述数据单元的时延信息。
在该方面中，在下行切换传输过程中，第一时间信息为以源网络设备定时为参考的时间信息，接收端设备把该时间信息转换为以目标网络设备定时为参考的时间信息，从而接收端设备可以统一采用以当前服务小区的定时来计算数据单元对应时延，降低了接收端设备的处理复杂度。
在一种可能的实现方式中，所述第二时间以目标网络设备的定时作为参考。
在另一种可能的实现方式中，所述接收端设备获取数据单元对应的第一时间的信息，包括：所述接收端设备从发送端设备接收所述数据单元对应的第一时间的信息。
在又一种可能的实现方式中，所述接收端设备为终端设备，所述发送端设备为目标网络设备，所述方法还包括：所述接收端设备接收来自所述发送端设备的第一指示，所述第一指示用于指示所述数据单元为从所述源网络设备转移至所述目标网络设备的数据单元。
在该实现方式中，可以通过明确的指示信息指示该数据单元为切换传输的数据单元，从而接收端设备根据该指示信息对时间信息进行处理。
在又一种可能的实现方式中，所述方法还包括：所述接收端设备向所述发送端设备发送所述时延信息。
在该实现方式中，终端设备在确定出时延信息后，向目标网络设备发送该时延信息，以使目标网络设备了解发送与接收之间的时延。
在又一种可能的实现方式中，所述第一时间的信息携带在服务数据适配协议SDAP协议数据单元PDU的报头中，或携带在PDCP PDU的报头中。
在又一种可能的实现方式中，所述第一时间信息包括以下一种或两种时间信息：相对时间信息、绝对时间信息。
在又一种可能的实现方式中，所述发送端设备为终端设备，所述接收端设备为目标网 络设备，所述方法还包括：所述接收端设备向网管系统发送所述时延信息。
第四方面，提供了一种通信装置，可以实现上述第一方面至第三方面中的任一方面或其中的任一种可能的实现方式中的通信方法。例如所述通信装置可以是芯片或者设备，可以通过软件、硬件、或者通过硬件执行相应的软件实现上述方法。
在一种可能的实现方式中，所述通信装置的结构中包括处理器、存储器；所述处理器被配置为支持所述装置执行上述通信方法中相应的功能。存储器用于与处理器耦合，其保存所述装置必要的程序(指令)和数据。可选的，所述通信装置还可以包括通信接口用于支持所述装置与其他网元之间的通信。
在另一种可能的实现方式中，所述通信装置，可以包括执行上述方法中的相应动作的单元模块。
对应于第一方面的通信方法，本申请提供的一种通信装置，包括：处理单元和通信单元；其中：
处理单元，用于获取数据单元对应的第一时间的信息，所述第一时间以源网络设备的定时作为参考；
所述处理单元还用于确定所述数据单元对应的第二时间的信息，所述第二时间以所述目标网络设备的定时作为参考；
通信单元，用于向接收端设备发送所述第二时间的信息。
可选地，所述通信单元还用于接收来自所述接收端设备的时延信息，其中，所述时延信息为所述接收端设备根据所述第二时间的信息与所述接收端设备获取所述数据单元的第三时间的信息计算得到的。
可选地，所述通信单元还用于从所述源网络设备接收所述数据单元对应的所述第一时间的信息。
可选地，所述处理单元还用于从包数据汇聚协议PDCP层获取所述数据单元对应的第一时间的信息。
对应于第二方面的通信方法，本申请提供的一种通信装置，包括：处理单元，还可包括通信单元；其中：
处理单元，用于获取数据单元对应的第一时间的信息，所述第一时间以源网络设备的定时作为参考；
所述处理单元还用于确定所述数据单元对应的第二时间的信息，所述第二时间以所述目标网络设备的定时作为参考；
所述处理单元还用于根据所述第二时间的信息和发送所述数据单元的时刻，确定所述数据单元的时延信息。
可选地，所述通信单元用于从所述源网络设备接收所述数据单元对应的第一时间的信息。
可选地，所述处理单元还用于从包数据汇聚协议PDCP层获取所述数据单元对应的第一时间的信息。
可选地，所述通信单元还用于向网管系统发送所述时延信息。
对应于第三方面的通信方法，本申请提供的一种通信装置，包括：处理单元，还可包 括通信单元；其中：
处理单元，用于获取数据单元对应的第一时间的信息，所述第一时间以源网络设备的定时作为参考；
所述处理单元还用于根据所述第一时间的信息、定时偏差、以及所述接收端设备获取所述数据单元的第二时间的信息，确定所述接收端设备获取所述数据单元的时延信息。
可选地，所述通信单元用于从发送端设备接收所述数据单元对应的第一时间的信息。
可选地，所述通信单元还用于接收来自所述发送端设备的第一指示，所述第一指示用于指示所述数据单元为从所述源网络设备转移至所述目标网络设备的数据单元。
可选地，所述通信单元还用于向所述发送端设备发送所述时延信息。
可选地，所述通信单元还用于向网管系统发送所述时延信息。
在又一种可能的实现方式中，包括处理器和收发装置，所述处理器与所述收发装置耦合，所述处理器用于执行计算机程序或指令，以控制所述收发装置进行信息的接收和发送；当所述处理器执行所述计算机程序或指令时，所述处理器还用于实现上述方法。其中，所述收发装置可以为收发器、收发电路或输入输出接口。当所述通信装置为芯片时，所述收发装置为收发电路或输入输出接口。
在又一种可能的实现方式中，所述通信装置的结构中包括处理器；所述处理器被配置为支持所述装置执行上述通信方法中相应的功能。
在又一种可能的实现方式中，所述通信装置的结构中包括处理器，所述处理器用于与存储器耦合，并读取存储器中的指令，并根据所述指令实现上述方法。
在又一种可能的实现方式中，所述通信装置的结构中包括收发器，用于实现上述通信方法。
当所述通信装置为芯片时，收发单元可以是输入输出单元，比如输入输出电路或者通信接口。当所述通信装置为网络设备时，收发单元可以是发送/接收器(也可以称为发送/接收机)。
第五方面，提供了一种计算机可读存储介质，所述计算机可读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执行时，实现上述各方面所述的方法。
第六方面，提供了一种包含指令的计算机程序产品，当该指令在计算机上运行时，使得计算机执行上述各方面所述的方法。
第七方面，提供了一种通信系统，包括上述第四方面和第五方面中的通信装置。
附图说明
图1-1为本申请涉及的一种通信系统的示意图；
图1-2示出了本申请实施例的CU实体和DU实体分离架构的接入网设备的协议栈示意图；
图2为本申请实施例提供的一种通信方法的流程示意图；
图3为在SDAP PDU的报文头中携带时间信息的报文格式示意图；
图4为示例的一个确定时间信息的示意图；
图5为示例的发送端设备确定第二时间的信息的流程示意图；
图6为PDCP PDU的报文头中携带时间信息的报文格式示意图；
图7为GTP-U的扩展头中携带时间信息的格式示意图；
图8为示例的另一个确定时间信息的示意图；
图9为本申请实施例提供的另一种通信方法的流程示意图；
图10为本申请实施例提供的又一种通信方法的流程示意图；
图11为示例的接收端设备确定第二时间的信息的流程示意图；
图12为本申请实施例提供的又一种通信方法的流程示意图；
图13为本申请实施例提供的一种通信装置的结构示意图；
图14为本申请实施例提供的又一种通信装置的结构示意图；
图15为本申请实施例提供的又一种通信装置的结构示意图。
具体实施方式
下面结合本发明实施例中的附图对本发明实施例进行描述。
图1-1给出了本申请涉及的一种通信系统的示意图。该通信系统可以包括至少一个网络设备100(图中仅示出1个)以及与网络设备100连接的一个或多个终端设备200。
网络设备100可以是能和终端设备200通信的设备。网络设备100可以是任意一种具有无线收发功能的设备。包括但不限于：基站NodeB、演进型基站eNodeB、第五代(the fifth generation，5G)通信系统中的基站、未来通信系统中的基站或网络设备、WiFi系统中的接入节点、无线中继节点、无线回传节点等。网络设备100还可以是云无线接入网络(cloud radio access network，CRAN)场景下的无线控制器。网络设备100还可以是小站，传输节点(transmission reference point，TRP)等。本申请的实施例对网络设备所采用的具体技术和具体设备形态不做限定。
终端设备200是一种具有无线收发功能的设备，可以部署在陆地上，包括室内或室外、手持、穿戴或车载；也可以部署在水面上，如轮船上等；还可以部署在空中，如飞机、气球和卫星上等。所述终端设备可以是手机(mobile phone)、平板电脑(pad)、带无线收发功能的电脑、虚拟现实(virtual reality，VR)终端设备、增强现实(augmented reality，AR)终端设备、工业控制(industrial control)中的无线终端、无人驾驶(self-driving)中的无线终端、远程医疗(remote medical)中的无线终端、智能电网(smart grid)中的无线终端、运输安全(transportation safety)中的无线终端、智慧城市(smart city)中的无线终端、智慧家庭(smart home)中的无线终端等等。本申请的实施例对应用场景不做限定。终端设备有时也可以称为用户设备(user equipment，UE)、接入终端设备、UE单元、移动站、移动台、远方站、远程终端设备、移动设备、终端(terminal)、无线通信设备、UE代理或UE装置等。
需要说明的是，本发明实施例中的术语“系统”和“网络”可被互换使用。“多个”是指两个或两个以上，鉴于此，本发明实施例中也可以将“多个”理解为“至少两个”。“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这三种情况。另外，字符“/”，如无特殊说明，一般表示前后关联对象是一种“或”的关系。
为了便于理解，首先介绍几个本申请实施例中涉及的概念，所述概念仅仅为了帮助理解本申请中的示例，对本申请实施例并没有限制作用。
无线资源控制(radio resource control,RRC)层：通信系统中的协议层，用于执行广播、寻呼、RRC链接建立、无线承载控制、移动、终端设备测量上报控制等。
服务数据适配协议(service data adaptation protocol,SDAP)层：该层为5G中新引入的一个协议层。负责把核心网或者应用层发送下来的各个服务质量(quality of service,Qos)流(flow)映射到无线接入层的数据资源承载(data resource bearer,DRB)，即根据Qos流对应的业务属性，把Qos流对应的数据单元放在对应的DRB上传输。
分组数据汇聚协议(packet data convergence protocol,PDCP)层：通信系统中的协议层，可执行诸如安全性、头压缩、加密之类的服务。PDCP层可以存在多个PDCP实体，每个实体承载一个无线承载(radio barrier,RB)的数据。PDCP层可以配置保证向上提交的数据是有序的，即按序提交。
无线链路控制层(radio link control,RLC)：通信系统中的协议层，执行诸如分段、重新装配、重传等服务。RLC层可以存在多个RLC实体，每个RLC实体为每个PDCP实体提供服务。RLC层也可以配置向上层提交的数据是有序的。
媒体接入控制(media access control,MAC)：通信系统中的协议层，对逻辑信道上的业务提供数据传输服务，执行诸如调度、混合自动重传请求(hybrid automatic repeat request,HARQ)的确认和否定服务。
物理(physical,PHY)层：对MAC层传下来的数据进行编码和传输。
服务数据单元(service data unit,SDU)和协议数据单元(protocol data unit,PDU):对于用户面而言：协议层由上至下分别为：SDAP层、PDCP层、RLC层、MAC层和PHY层，或者上述协议层也可以不包括SDAP层。对于控制面而言，协议层由上至下分别为：RRC层、PDCP层、RLC层、MAC层和PHY层。对于每一层而言，从上一层输入的数据称为本层的SDU。每一层处理后的数据，在本层称为PDU。比如PDCP层输入给RLC层的数据，对于PDCP层而言，称为PDCP PDU，对于RLC层而言，称为RLC SDU。在本发明的所有实施例中，数据单元可能是指PDU或者SDU中的任何一个。
在一种可能的方式中，接入网设备可以是集中式单元(centralized unit,CU)实体和分布式单元(distributed unit,DU)实体分离的架构。例如，图1-2示出了本申请实施例的CU实体和DU实体分离架构的接入网设备的协议栈示意图。CU和DU可以理解为是对接入网设备从逻辑功能角度的划分，CU实体为CU功能对应的实体，DU实体为DU功能对应的实体。其中，CU实体和DU实体在物理上可以是分离的，也可以部署在一起。多个DU实体可以共用一个CU实体。一个DU实体也可以连接多个CU实体(图1-2中未示出)。CU实体和DU实体之间可以通过接口相连，例如可以是F1接口。CU实体和DU实体可以根据无线网络的协议层划分。例如，RRC协议层、SDAP协议层以及PDCP协议层的功能设置在CU实体中，而RLC协议层，MAC协议层，PHY协议层等的功能设置在DU实体中。可以理解，对CU实体和DU实体处理功能按照这种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实体或者DU实体划分为具有更多协议层的功能。例如，CU实体或DU实体还可以划分为具有协议层的部分处理功能。在一种可能设 计中，将RLC协议层的部分功能和RLC协议层以上的协议层的功能设置在CU实体，将RLC协议层的剩余功能和RLC协议层以下的协议层的功能设置在DU实体。在另一种可能的设计中，还可以按照业务类型或者其他系统需求对CU实体或者DU实体的功能进行划分。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实体，不需要满足该时延要求的功能设置在CU实体。在另一种可能的设计中，CU实体也可以具有核心网的一个或多个功能。一个或者多个CU实体可以集中设置，也可以分离设置。例如CU实体可以设置在网络侧方便集中管理。DU实体可以具有多个射频功能，也可以将射频功能拉远设置。
CU实体的功能可以由一个功能实体来实现也可以由不同的功能实体实现。例如，可以对CU实体的功能进行进一步切分，例如，将控制面(control plane，CP)和用户面(user plane，UP)分离，即CU实体包括CU的控制面(CU-CP)实体和CU用户面(CU-UP)实体，该CU-CP实体和CU-UP实体可以与DU实体相耦合，共同完成接入网设备的功能。一种可能的方式中，CU-CP实体负责控制面功能，主要包含RRC协议层和PDCP控制面(PDCP control plane，PDCP-C)协议层。PDCP-C协议层主要负责控制面数据的加解密，完整性保护，数据传输等。CU-UP实体负责用户面功能，主要包含SDAP协议层和PDCP用户面(PDCP user plane，PDCP-U)协议层。其中，SDAP协议层主要负责将核心网的数据流(flow)映射到承载。PDCP-U协议层主要负责数据面的加解密，完整性保护，头压缩，序列号维护，数据传输等。其中，本申请实施例中，CU-CP实体和CU-UP实体通过E1接口连接，CU-CP实体通过F1-C(控制面)接口和DU实体连接，CU-UP实体通过F1-U(用户面)接口和DU实体连接。此外，CU-CP实体代表接入网设备和核心网的控制面(比如第四代(4th generation，4G)核心网的移动管理实体(mobility management entity，MME)，或者5G核心网(5G core，5GC)的接入移动管理功能(access and mobility management function，AMF)网元)连接；CU-UP实体代表接入网设备和核心网的用户面(比如4G核心网的服务网关(serving gateway，SGW)，或者5G核心网的用户面功能(user plane function，UPF)网元)连接；DU实体代表接入网设备和终端设备连接。当然，还有一种可能的实现是PDCP-C也在CU-UP实体中，本申请实施例对此不作具体限定。
本申请提供了一种通信方法及装置，在切换传输过程中，第一时间信息为以源网络设备定时为参考的时间信息，发送端设备把该时间信息转换为以目标网络设备定时为参考的时间信息，从而接收端设备可以统一采用当前服务小区的定时，降低了接收端设备的处理复杂度。
在切换场景下(即UE从源网络设备切换到目标网络设备)，源网络设备需要把从核心网接收的且还没被UE正确接收的下行数据单元和从UE接收的乱序的数据单元转移到目标网络设备。乱序是指在源网络设备从终端正确接收到的数据单元之前的一些数据单元并没有被源网络设备正确接收(例如，收到了packet 2/3，但还没收到packet1)。对于某个PDU会话(session)而言，具体又分为有损切换和无损切换：
1)对于那些无需无损切换的服务质量(quality of service，QoS)流(flow)，例如，承载在非确认模式(Unacknowledged Mode，UM)的数据无线承载(data radio bearer， DRB)上的QoS flow，源网络设备通过PDU session级别的隧道，把这些QoS flow的下行数据单元转移给目标网络设备。通过PDU session级别的隧道转移的数据单元是以SDAP SDU形式(即不携带SDAP层的报头)转移的。
2)对于那些需无损切换的QoS flow(例如，承载在确认模式(Acknowledged Mode，AM)的DRB上的QoS flow)，源网络设备通过DRB级别的下行隧道，即源网络设备的每个需要无损的DRB都建立对应的隧道，把这些DRB上还未被UE正确接收的下行数据单元转移给目标网络设备。源网络设备通过DRB级别的上行隧道，把这些DRB上接收到的乱序数据单元转移给目标网络设备。且为了按序提交，源网络设备还需要通知目标网络设备：每个DRB中源网络设备为UE配置的QoS flow与DRB映射关系，以及序列号(Sequence Number，SN)状态。SN状态包括上行PDCP SN和超帧号(Hyper Frame Number，HFN)的接收状态和下行PDCP SN和HFN的发送状态，具体为在某个DRB对应下行数据单元分配的下一个计数count值，该count值包括对应数据单元的PDCP的SN号和超帧号、源网络设备在该DRB对应上行数据单元接收情况(没有正确接收的第一个PDCP数据单元对应的计数count值，该count值包括对应数据单元的PDCP的SN号和超帧号，及该PDCP数据单元之后其他数据单元的上行接收情况)。这样就能保证在切换过程中下行和上行数据单元在切换前后的PDCP的SN号是连续的，这样能保证接收端可以按序提交对应的数据单元。通过DRB级别的隧道转移的数据是以SDAP PDU形式(即携带SDAP层的报头)转移的。
另外，转移的数据单元都是采用GPRS用户面隧道协议(GPRS Tunnelling protocol user plane，GTP-U)格式来携带的，即采用GTP-U协议。
UE发生移动或切换，可以是从源网络设备移动或切换至目标网络设备，源网络设备和目标网络设备是两个不同的网络设备；也可以是从一个网络设备的一个小区(称为“源小区”)移动或切换至另一个小区(称为“目标小区”)。源网络设备和目标网络设备可以有不同的定时，源小区和目标小区也可以有不同的定时。比如这里的定时是指源网络设备、目标网络设备、源小区、目标小区对应的无线帧号、子帧号、时隙号、符号号等。下面实施例的描述以从源网络设备移动或切换至目标网络设备为例进行描述。实际上，也可以替换为源小区和目标小区之间的移动或切换。可选地，源网络设备和目标网络设备还可能指双链接场景下的主基站和辅基站，网络侧把一些Qos流在主基站和辅基站之间切换。
图2为本申请实施例提供的一种通信方法的流程示意图，该方法包括以下步骤：
S201、发送端设备获取数据单元对应的第一时间的信息。
在下行切换传输中，源网络设备需要把从核心网接收的且还没被UE正确接收的下行数据单元和从UE接收的乱序的数据单元转移到目标网络设备，也可能需要把从核心网接收到的新下行数据(比如还没有分配PDCP SN号的下行数据)转移到目标网络设备，发送端设备可以是目标网络设备，对应的接收端设备可以是终端设备；在终端设备发送数据单元的过程中，例如向目标网络设备重传数据，发送端设备可以是终端设备，对应的接收端设备可以是目标网络设备。
发送端设备首先获取数据单元对应的第一时间的信息，其中，第一时间以源网络设备 的定时作为参考。
在一个实现方式中，在下行切换传输过程中，所述发送端设备是目标网络设备，所述发送端设备获取数据单元对应的第一时间的信息，包括：所述发送端设备从所述源网络设备接收所述数据单元对应的第一时间的信息。具体地，第一时间的信息可以在数据单元中携带，也可能在GTP-U的报头或者扩展头中携带。
可选地，源网络设备向目标网络设备发送切换时转移的数据单元，并发送该数据单元对应的第一时间的信息，所述第一时间是以源网络设备的定时作为参考的。
在下行数据传输过程中，如果UE从源网络设备移动到目标网络设备，源网络设备需要把从核心网接收到的且还没被UE正确接收的下行数据转移到目标网络设备，也可能需要把从核心网接收到的新下行数据(比如还没有分配PDCP SN号的下行数据)转移到目标网络设备。本实施例中，源网络设备向目标网络设备发送切换时转移的数据单元时，也发送第一时间的信息。该第一时间是源网络设备从核心网接收到数据单元中的数据的时刻或者源网络设备生成该数据单元的时刻，且第一时间以源网络设备的定时作为参考。可选的，第一时间可能是源网络设备从核心网接收到该数据单元对应的数据包到源网络设备生成该数据单元之间的任一时刻。
在另一个实现方式中，发送端设备获取数据单元对应的第一时间的信息，包括：所述发送端设备从PDCP层获取所述数据单元对应的第一时间的信息。具体实现中，发送端设备的PDCP层从源网络设备获取数据单元，该第一时间为发送端设备的其它协议栈层在进行后续处理过程中，从PDCP层获取数据单元对应的时间。或者包括所述发送端设备从SDAP层获取所述数据单元对应的第一时间的信息。具体实现中，发送端设备的SDAP层从源网络设备获取数据单元，该第一时间为发送端设备的其它协议栈层在进行后续处理过程中，从SDAP层获取数据单元对应的时间。
在又一个实现方式中，在终端设备发送数据单元的过程中，该发送端设备为终端设备，所述发送端设备获取数据单元对应的第一时间的信息，包括：所述发送端设备获取通过所述源网络设备发送所述数据单元时对应的第一时间的信息。具体地，UE记录向源网络设备发送数据单元的时刻，或者UE的无线协议层(比如SDAP或PDCP层)从上层(比如应用层或IP层)收到该数据单元的时刻，或者UE的无线协议层(比如SDAP或PDCP层)向下一层发送该数据单元的时刻，或者UE的无线协议层(比如SDAP或PDCP层)从上层(比如应用层或IP层)收到该数据单元与UE的无线协议层(比如SDAP或PDCP层)向下一层发送该数据单元的时刻之间的任何一个时刻，即第一时间。该第一时间是以源网络设备的定时作为参考的。
在又一个实现方式中，发送端设备获取数据单元对应的第一时间的信息，包括：所述发送端设备从PDCP层获取所述数据单元对应的第一时间的信息。即第一时间还可能是指示终端设备的某个协议层从上一层收到数据包的时刻，比如SDAP或者PDCP层从应用层收到数据包，或者PDCP层从SDAP层收到数据包的时刻。或者第一时间是指终端设备的某个协议层从上一层收到数据包的时刻到该协议层把该数据包发送给下一层的时刻之间的任何一个时刻。
可选地，第一时间的信息可能是一种相对时间的形式，比如以帧号、子帧号、时隙号 中至少一种形式来标识，也可能是相对某个参考时刻的时间偏移(比如相对某个帧号、子帧号、时隙号的时间偏移)。比如源网络设备通过RRC消息或者广播消息通知UE对应的参考时刻的规则，或者协议中规定了该规则，例如，参考时刻的帧号、子帧号、时隙号满足一定的规则，比如帧号进行模10运算等于0。也可能参考时刻是某个帧对应的绝对时间(比如某个广播消息所下发的绝对时间，绝对时间可以是协调世界时间(coordinated universal time,UTC)时间UTC时间，也可能是是GPS时间)。在切换之前，源网络设备和UE也可以按照这些规则测量不是从源网络设备转移至目标网络设备的数据单元对应的时延。
S202、所述发送端设备确定所述数据单元对应的第二时间的信息。
发送端设备确定数据单元对应的第二时间的信息，该第二时间以目标网络设备的定时作为参考。
可选地，所述第二时间是根据所述第一时间和定时偏差确定的，所述定时偏差包括所述目标网络设备与所述源网络设备的定时偏差。
接收端设备获取到第一时间的信息后，由于不同网络设备的无线定时是独立的，因此，不同网络设备之间存在定时偏差。定时偏差是指不同网络设备之间的无线帧号的偏移和无线帧边界的偏移。可选的，该偏移可能是从UE角度观察到的定时偏差。因此，接收端设备根据第一时间的信息和定时偏差，确定第二时间的信息。发送端设备在接收到源网络设备转移的数据单元后，需要对该数据单元进行下一步处理，即传输给接收端设备，为保证接收端设备可以统一采用当前服务小区的定时，降低接收端设备的处理复杂度，则该第二时间是以目标网络设备的定时作为参考的。例如，在下行切换传输过程中，目标网络设备从源网络设备接收到转移的数据单元后，将数据单元传输给UE，同时发送第二时间的信息给UE。又例如，在UE发送数据单元的过程中，UE向源网络设备发送数据单元并未成功，且此时，UE发生了小区切换，UE需要向目标网络设备重传该数据单元，或者UE还没有向源网络设备发送数据单元但已经为该数据单元分配了PDCP SN号(或者已经组成PDCP PDU)，UE需要按照目标网络设备的格式重新组成PDCP PDU并发送该数据单元。为了准确计算UE传输该数据单元的时延，UE根据上述第一时间的信息和定时偏差，确定第二时间的信息。其中，所述第二时间是以目标网络设备的定时作为参考的。
S203、所述发送端设备向接收端设备发送所述第二时间的信息。
发送端设备在确定第二时间的信息后，发送该第二时间的信息给接收端设备。接收端设备接收该第二时间的信息。从而接收端设备可以统一采用当前服务小区的定时进行后续的处理，降低接收端设备的处理复杂度。
发送端设备将从源网络设备接收到转移的数据单元发送给接收端设备，并发送该数据单元对应的第二时间的信息，该第二时间是以目标网络设备的定时作为参考的。这样，对应的第二时间考虑了数据单元转移过程中所耗时间。
可选地，发送端设备可以是在某个无线协议层(比如SDAP层或PDCP层)把该数据单元发送给接收端设备。具体地，发送端设备可能是在SDAP PDU或者PDCP PDU中把该第二时间的信息发送给接收端设备。进一步地，在下行切换传输过程中，发送端设备为目标网络设备，接收端设备为终端设备，上述方法还可以包括以下步骤：所述发送端设备 接收来自接收端设备的时延信息，所述时延信息为所述接收端设备根据所述第二时间的信息与所述接收端设备获取所述数据单元的第三时间的信息计算得到的。
例如，当发送端设备是目标网络设备时，UE从目标网络设备接收所述数据单元。UE可以根据该数据单元对应的第二时间的信息、以及UE获取所述数据单元的第三时间的信息，计算得到从该数据单元在无线传输中所耗的时延。
可选的，所述所述数据单元的第三时间可能是指终端设备在某个无线协议层(比如SDAP层或PDCP层)收到该数据单元到把该数据单元提交给上层(比如IP层)之间的任何一个时刻。
终端设备向目标网络设备发送该时延信息。目标网络设备接收该时延信息，可以了解数据单元在无线网络侧传输对应的时延信息。终端设备可能是反馈某个数据单元的时延信息，也可能反馈的是多个数据单元对应的时延信息。
进一步地，在UE发送单元的过程中，所述目标网络设备可以根据所述第二时间的信息、以及所述目标网络设备获取所述数据单元的第三时间，确定数据单元的时延。
目标网络设备在成功接收及译码出UE传输的数据单元后，可以根据第二时间的信息、以及目标网络设备获取所述数据单元的第三时间，计算数据单元的时延。该时延即为第三时间与第二时间之间的差。
可选地，所述第三时间可以是指目标网络设备成功收到该数据单元到目标网络设备把该数据单元中的数据发送给核心网之间的任何一个时刻。
根据本申请实施例提供的一种通信方法，在切换传输过程中，第一时间信息为以源网络设备定时为参考的时间信息，发送端设备把该时间信息转换为以目标网络设备定时为参考的时间信息，从而接收端设备可以统一采用当前服务小区的定时，降低了接收端设备的处理复杂度。
具体实现中，以下行切换传输为例，目标网络设备作为发送端设备，由目标网络设备确定第二时间的信息。包括以下A1～A16等多种实现方式：
实现方式A1、源网络设备以SDAP PDU/PDCP SDU形式转移切换的数据单元给目标网络设备。源网络设备在SDAP PDU的报文头中携带了相对时间信息(第一时间的信息)，且目标网络设备根据第一时间的信息和定时偏差，得到第二时间的信息。目标网络设备在发送给UE的SDAP PDU的报文头中携带了该第二时间的信息。其中，如图3所示，为在SDAP PDU的报文头中携带时间信息的报文格式示意图，可以通过时延测量指示(latency measurement indication，LMI)指示SDAP PDU是否携带了时间信息，时间信息(time stamp)位于SDAP PDU的第三字节(Oct3)和第四字节(Oct4)。数据位于第五字节及之后的若干字节中。可选地，也可以不包括LMI。当然，这里仅为示例，时间信息还可以位于SDAP PDU的其它字节。SDAP SDU加上报文头(反射服务质量流到无线承载映射指示(reflective QoS flow to DRB mapping indication，RDI)、反射服务质量流指示(reflective QoS indication，RQI)和服务质量流标识(QoS flow ID，QFI)即为SDAP PDU，其携带时间信息的格式可参考图3所示。
可选地，这里的相对时间可能是以帧号、子帧号、时隙号中至少一种形式来标识，也 可能是相对某个参考时刻的时间偏移(比如相对某个帧号、子帧号、时隙号的时间偏移)。
具体地，目标网络设备根据如下方式确定第二时间的信息：目标网络设备根据源网络设备在SDAP PDU中携带的第一时间的信息和两个网络设备的定时偏差进行确定。例如：源网络设备与目标网络设备之间的定时偏差为Diff＝T_source-T_target，SDAP PDU携带的第一时间的信息以源网络设备的定时为参考对应为T_source，对应的时刻为绝对时间T1。该绝对时间T1，以目标网络设备的定时为参考对应为T_target，则目标网络设备在给UE发送数据单元对应的时间信息是以目标网络设备的定时为参考的T_target对应的相对时间。例如，如图4所示的示例的一个确定时间信息的示意图，源网络设备转移过来的SDAP PDU的时间信息是用帧号和子帧号表示(这里只是以这个为举例，可能还包括时隙号等)，例如，帧号为frame 1，子帧号为subframe 1，对应的绝对时间为T1，而同一绝对时间时刻在目标网络设备的相对时间为frame 1，子帧号为subframe 2，所以目标网络设备给UE发送的时间形式是frame 1，子帧号为subframe 2。可选地，目标网络设备给UE发送的时间信息是能代表第二时间的其他形式，比如只用frame 1对应的帧号的低比特来指示frame 1，这里的低比特是指帧号对应的二进制比特中的低比特(比如帧号20，对应10比特二进制为0000010100，则低比特是指10100)，也可以称为指帧号的次重要比特。可选地，本申请中的绝对时间可能是GPS时间或者协调世界时(coordinated universal time,UTC)等。
根据以上实现方式A1，具体地，如图5所示的一个示例的发送端设备确定第二时间的信息的流程示意图，该方法包括以下步骤：
S501、在下行切换传输过程中，目标网络设备获取数据单元对应的第一时间的信息。
例如，第一时间T1是以源网络设备的定时作为参考，具体为帧1，子帧1。
具体地，目标网络设备可以是从源网络设备获取该第一时间的信息，也可以是从上一个协议层获取该第一时间的信息。
可选地，目标网络设备还从源网络设备接收该数据单元。
S502、所述目标网络设备确定所述数据单元对应的第二时间的信息。其中，第二时间以目标网络设备的定时作为参考，第二时间具体为帧1，子帧2。
S503、所述目标网络设备向终端设备发送所述第二时间的信息。
可选地，所述目标网络设备还向所述终端设备发送所述数据单元。
S504、所述终端设备根据所述第二时间的信息和接收到所述数据单元的第三时间的信息，确定时延信息。
其中，第三时间T2以目标网络设备的定时作为参考，T2为帧1，子帧3。
终端设备统一以目标网络设备的定时作为参考，则确定时延＝T2-T1。即时延＝(帧1，子帧3)-(帧1，子帧2)＝一个子帧。
S505、终端设备向目标网络设备发送该时延信息。
以上S501～S505为下行切换传输过程。与下面的终端设备发送数据单元的过程可以是独立的。
S506、在终端设备发送数据单元的过程中，例如终端设备重传数据单元给目标网络设备的过程中，终端设备获取数据单元对应的第一时间信息，并确定所述数据单元对应的第二时间的信息。
例如，UE向源网络设备发送数据单元的第一时间T3，以源网络设备的定时作为参考，则T3为帧2，子帧1。UE根据第一时间的信息和定时偏差，确定以目标网络设备的定时作为参考的第一时间T3为帧2，子帧2。
S507、所述终端设备向所述目标网络设备发送所述第二时间的信息。
S508、所述目标网络设备根据第二时间的信息和接收到所述数据单元的第三时间的信息，确定时延信息。
例如，目标网络设备接收到数据单元的第三时间T4，以目标网络设备的定时作为参考，T4为帧2，子帧3，则时延＝T4-T3＝(帧2，子帧3)-(帧2，子帧4)＝一个子帧。
采用实现方式A1，可以实现无损切换。本实现方式针对的场景是源网络设备和目标网络设备在给终端设备发送数据单元时，源网络设备在SDAP PDU的报文头中携带了第一时间的信息，目标网络设备在发送给UE的SDAP PDU的报文头中携带了第二时间的信息。第一时间的信息为以源网络设备定时为参考的相对时间信息，目标网络设备把第一时间信息转化为以目标网络设备定时为参考的相对时间，从而终端设备可以统一采用以当前服务小区的定时来计算数据单元对应的时延，降低了终端设备的处理复杂度。
实现方式A2、源网络设备以SDAP PDU/PDCP SDU形式转移切换的数据单元给目标网络设备。源网络设备在GTP-U的扩展头中携带了相对时间信息(第一时间的信息)，目标网络设备在发送给UE的PDCP PDU的报文头中携带了第二时间的信息。其中，如图6所示，为PDCP PDU的报文头中携带时间信息的报文格式示意图，其中，LMI指示PDCP PDU是否携带了时间信息，时间信息(time stamp)位于PDCP PDU的第三字节和第四字节，当然，还可以位于其它的字节，在此不作限制。数据位于第五字节及之后的若干字节中。GTP-U是网络设备之间传输的协议，如图7所示，为GTP-U的格式示意图，其中，传输包数据单元(transport packet data unit，T-PDU)用来携带切换转移的SDAP PDU/PDCP SDU，T-PDU还可能是因特网协议(internet protocol,IP)报文(datagram)。在(GTPv1-U Header)中携带了GTP-U的扩展头，扩展头中携带了时间信息。用户报文协议/因特网协议(user datagram protocol/internet protocol,UDP/IP)是传输GTP消息的路径协议。GTP封装用户面数据单元(GTP encapsulated user plane data unit,G-PDU)是指GTP协议中携带的用户面数据内容。
可选地，这里的相对时间是指可能是以帧号、子帧号、时隙号中至少一种形式来标识，也可能是相对某个参考时刻的时间偏移(比如相对某个帧号、子帧号、时隙号的时间偏移)。
具体地，目标网络设备根据如下方式确定第二时间的信息：目标网络设备根据GTP-U携带的时间信息和两个小区的定时偏差进行确定。例如：源网络设备和目标网络设备之间的定时偏差为Diff＝T_source-T_target，GTP-U的扩展头携带的第一时间的信息以源网络设备的定时为参考对应为T_source，对应的时刻为绝对时间T1。该绝对时间T1，以目标网络设备的定时为参考对应为T_target，则目标网络设备在给UE发送数据单元对应的时间信息是以目标网络设备的定时为参考的T_target对应的相对时间。例如，GTP-U的扩展头的时间信息是用帧号，子帧号表示，例如，是帧号为frame 1，子帧号为subframe 1，对应的绝对时间为T1，而同一时刻在目标网络设备的相对时间为frame 1，子帧号为subframe 2，所以目标网络设备给UE发送的时间形式是frame 1，子帧号为subframe 2。可选地，目标网 络设备给UE发送的时间信息是能代表第二时间的其他形式，比如只用frame 1对应的帧号的低比特来指示frame 1。
采用实现方式A2，可以实现无损切换。本实现方式针对的场景是源网络设备和目标网络设备在给终端设备发送数据单元时，源网络设备在GTP-U的扩展头中携带了第一时间的信息，目标网络设备在发送给UE的PDCP PDU的报文头中携带了第二时间的信息。第一时间的信息为以源网络设备定时为参考的相对时间信息，目标网络设备把第一时间信息转化为以目标网络设备定时为参考的相对时间，从而终端设备可以统一采用以当前服务小区的定时来计算数据单元对应的时延，降低了终端设备的处理复杂度。
实现方式A3、源网络设备以SDAP PDU/PDCP SDU形式转移切换的数据单元给目标网络设备。源网络设备在GTP-U的扩展头中携带了绝对时间信息(第一时间的信息对应的绝对时间)，且目标网络设备在发送给UE的SDAP PDU的报文头中携带了第二时间的信息。可选地，GTP-U中携带的该绝对时间信息为源网络设备收到数据单元中的数据包的时刻，例如，源网络设备的SDAP层收到SDAP SDU的时刻，或源网络设备的PDCP层收到PDCP SDU的时刻。
具体地，目标网络设备根据如下方式确定第二时间的信息：目标网络设备根据GTP-U中的绝对时间进行确定。例如：GTP-U中携带的绝对时间为T_absolute，则目标网络设备根据自身设置的绝对时间与相对时间的关系，把T_absolute设置为自身的相对时间。例如，如图4所示，T_absolute为T1，则目标网络设备知道T1绝对时间在目标网络设备对应的相对时间为frame 1，subframe 2，这样目标网络设备就知道设置相对时间为frame 1，subframe2。可选地，目标网络设备给UE发送的时间信息是能代表第二时间的其他形式，比如只用frame 1对应的帧号的低比特来指示frame 1。
采用实现方式A3，可以实现无损切换。本实现方式针对的场景是源网络设备和目标网络设备在给终端设备发送数据单元时，源网络设备在GTP-U的扩展头中携带了绝对时间信息，目标网络设备把该绝对时间信息转换为以目标网络设备定时为参考的相对时间，目标网络设备在发送给UE的SDAP PDU的报文头中携带了第二时间的信息，从而终端设备可以统一采用以当前服务小区的定时来计算数据单元对应的时延，降低了终端设备的处理复杂度。
实现方式A4、源网络设备以SDAP PDU/PDCP SDU形式转移切换的数据单元给目标网络设备。源网络设备在GTP-U的扩展头中携带了绝对时间信息(第一时间的信息对应的绝对时间)，且目标网络设备在发送给UE的PDCP PDU的报文头中携带了第二时间的信息。可选地，GTP-U中携带的该绝对时间为源网络设备收到数据单元的时刻，例如为源网络设备的PDCP层收到PDCP SDU的时刻，或者源网络设备的SDAP层收到SDAP SDU的时刻。
具体地，目标网络设备根据如下方式确定第二时间的信息：目标网络设备根据GTP-U中的绝对时间确定第二时间的信息。例如：GTP-U中携带的绝对时间为T_absolute，则目标网络设备根据自身设置的绝对时间与相对时间的关系，把T_absolute设置为自身的相对时间。例如，如图4所示，T_absolute为T1，则目标网络设备知道T1绝对时间在目标网络设备对应的相对时间为frame 1,subframe 2，这样目标网络设备就知道设置相对时间为frame 1，subframe 2。可选地，目标网络设备给UE发送的时间信息是能代表第二时间的其他形 式，比如只用frame 1对应的帧号的低比特来指示frame 1。
采用实现方式A4，可以实现无损切换。本实现方式针对的场景是源网络设备和目标网络设备在给终端设备发送数据单元时，源网络设备在GTP-U的扩展头中携带了绝对时间信息，目标网络设备在发送给UE的PDCP PDU的报文头中携带了第二时间的信息，目标网络设备把该绝对时间信息转换为以目标网络设备定时为参考的相对时间，从而终端设备可以统一采用以当前服务小区的定时来计算数据单元对应的时延，降低了终端设备的处理复杂度。
实现方式A5、源网络设备以SDAP PDU/PDCP SDU形式转移切换的数据单元给目标网络设备。源网络设备在SDAP PDU的报文头中携带了相对时间信息(第一时间的信息)，且目标网络设备在发送给UE的SDAP PDU的报文头中携带了第二时间的信息。
具体地，目标网络设备根据如下方式确定第二时间的信息：目标网络设备根据SDAP PDU携带的时间信息和两个小区的定时偏差进行确定。例如，如图8所示的示例的另一个确定时间信息的示意图，源网络设备和目标网络设备之间的定时偏差为Diff＝T_source-T_target，SDAP PDU携带的时间信息对应的时刻为T1，T1对应的绝对时间参考点是参考点1，相对时间为相对时间1(源网络设备转移给目标网络设备的SDAP PDU报文头中携带的相对时间信息，即第一时间的信息)。则目标网络设备在给UE发送数据时携带的时刻在绝对时间上为T1，并按照该时刻T1设置目标网络设备给UE发送的时间信息，例如，时间参考点是时间参考点2，相对时间为相对时间2。例如，目标网络设备知道源网络设备发送的绝对时间参考点的信息(即目标网络设备知道源网络设备的绝对时间参考点的时域位置)，例如，时域位置是指帧号，子帧号等的位置信息，这样目标网络设备根据定时偏差知道该数据单元对应的时间参考点是哪一个，从而知道对应的绝对时间T1，目标网络设备再根据绝对时间T1获得在目标网络设备对应的绝对时间参考点2和相对时间2，之后再在给UE的SDAP PDU报文头中携带相对时间2。
在一个示例中，例如，每隔100个帧发送一个广播消息，广播消息中下发了该广播消息时刻对应的绝对时间，而数据单元中携带的相对时间是相对之前的一个广播消息携带的时间偏移。
目标网络设备知道某个绝对时间T1对应的时间点，且知道绝对时间和时间参考点的对应关系，从而知道相对时间。在一个示例中，例如，T1是2018年11月5日15点23分11秒11毫秒。而目标网络设备知道自己每个绝对时间的参考点，例如，每20分钟一个参考点，第一个时间参考点是2018年11月5日15点23分，第二个时间参考点是2018年11月5日15点43分，……这样目标网络设备就知道T1时刻的时间参考点是参考点1，相对时间就是T1和该参考点1对应的绝对时间的差值，即相对时间是11秒11毫秒。
采用实现方式A5，可以实现无损切换。本实现方式针对的场景是源网络设备和目标网络设备在给终端设备发送数据单元时，源网络设备在SDAP PDU的报文头中携带了第一时间的信息，目标网络设备在发送给UE的SDAP PDU的报文头中携带了第二时间的信息。第一时间的信息为以源网络设备定时为参考的相对时间信息，目标网络设备把第一时间信息转化为以目标网络设备定时为参考的相对时间，从而终端设备可以统一采用以当前服务小区的定时来计算数据单元对应的时延，降低了终端设备的处理复杂度。
实现方式A6、源网络设备以SDAP PDU/PDCP SDU形式转移切换的数据单元给目标网络设备。源网络设备在GTP-U的扩展头中携带了相对时间信息(第一时间的信息)，且目标网络设备在发送给UE的PDCP PDU的报文头中携带了第二时间的信息。
具体地，目标网络设备根据如下方式确定第二时间的信息：目标网络设备根据GTP-U携带的相对时间信息和两个小区的定时偏差进行确定。例如，源网络设备和目标网络设备之间的定时偏差为Diff＝T_source-T_target，GTP-U的扩展头携带的时间信息对应的时刻为T1，T1对应的绝对时间参考点是参考点1，相对时间为相对时间1(源网络设备转移给目标网络设备的GTP-U的扩展头中携带的相对时间信息)，则目标网络设备在给UE发送数据时携带的时刻在绝对时间上为T1,并按照该时刻T1设置目标网络设备给UE发送的时间信息，例如，时间参考点是时间参考点2，相对时间为相对时间2。例如，目标网络设备知道源网络设备发送的绝对时间参考点的信息(即目标网络设备知道源网络设备的绝对时间参考点的时域位置)，例如，时域位置是指帧号，子帧号的位置信息。这样目标网络设备根据定时偏差知道该数据单元对应的时间参考点是哪一个，从而知道对应的绝对时间T1，目标网络设备再根据绝对时间T1获得在目标网络设备对应的绝对时间参考点2和相对时间2，之后再在给UE的PDCP PDU报文头中携带相对时间2。
采用实现方式A6，可以实现无损切换。本实现方式针对的场景是源网络设备和目标网络设备在给终端设备发送数据单元时，源网络设备在GTP-U的扩展头中携带了第一时间的信息，目标网络设备在发送给UE的PDCP PDU的报文头中携带了第二时间的信息。第一时间的信息为以源网络设备定时为参考的相对时间信息，目标网络设备把第一时间信息转化为以目标网络设备定时为参考的相对时间，从而终端设备可以统一采用以当前服务小区的定时来计算数据单元对应的时延，降低了终端设备的处理复杂度。
实现方式A7、源网络设备以SDAP PDU/PDCP SDU转移切换的数据单元给目标网络设备。源网络设备在GTP-U的扩展头中携带了绝对时间和相对时间信息，或者绝对时间信息，且目标网络设备在发送给UE的SDAP PDU的报文头中携带了修改后的时间信息。
具体地，目标网络设备根据如下方式确定第二时间的信息：目标网络设备根据GTP-U中携带的绝对时间设置目标网络设备给UE发送的绝对时间和相对时间(第二时间)。例如：GTP-U中携带的绝对时间和相对时间信息对应的绝对时间为T1或者GTP-U中携带的绝对时间信息为绝对时间T1，则目标网络设备根据该绝对时间T1设置给UE发送的绝对时间和相对时间。例如，在目标网络设备中绝对时间T1对应的时间参考为绝对时间参考2，相对时间为相对时间2，则目标网络设备给UE发送的第二时间的信息就携带的是相对时间2。
采用实现方式A7，可以实现无损切换。本实现方式针对的场景是源网络设备和目标网络设备在给终端设备发送数据单元时，源网络设备在GTP-U的扩展头中携带了第一时间的信息，目标网络设备在发送给UE的SDAP PDU的报文头中携带了第二时间的信息。第一时间的信息为绝对时间信息和相对时间信息，或绝对时间信息，目标网络设备把第一时间信息转化为以目标网络设备定时为参考的相对时间，从而终端设备可以统一采用以当前服务小区的定时来计算数据单元对应的时延，降低了终端设备的处理复杂度。
实现方式A8、源网络设备通过SDAP PDU/PDCP SDU转移切换的数据单元给目标网络设备。源网络设备在GTP-U的扩展头中携带了绝对时间和相对时间信息，或者绝对时间 信息，且目标网络设备在发送给UE的PDCP PDU的报文头中携带了第二时间的信息。
具体地，目标网络设备根据如下方式确定第二时间的信息：目标网络设备根据GTP-U中携带的绝对时间设置目标网络设备给UE发送的绝对时间和相对时间。例如：GTP-U中携带的绝对时间和相对时间信息对应的绝对时间为T1或者GTP-U中携带的绝对时间信息为绝对时间T1，则目标网络设备根据该绝对时间T1设置给UE发送的绝对时间和相对时间。例如，在目标网络设备中绝对时间T1对应的时间参考为绝对时间参考2，相对时间为相对时间2。
采用实现方式A8，可以实现无损切换。本实现方式针对的场景是源网络设备和目标网络设备在给终端设备发送数据单元时，源网络设备在GTP-U的扩展头中携带了第一时间的信息，目标网络设备在发送给UE的PDCP PDU的报文头中携带了第二时间的信息。第一时间的信息为绝对时间信息和相对时间信息，或绝对时间信息，目标网络设备把第一时间信息转化为以目标网络设备定时为参考的相对时间，从而终端设备可以统一采用以当前服务小区的定时来计算数据单元对应的时延，降低了终端设备的处理复杂度。
实现方式A9、源网络设备以SDAP SDU形式转移切换的数据单元给目标网络设备。源网络设备在GTP-U的扩展头中携带相对时间信息(第一时间的信息)，且目标网络设备在发送给UE的SDAP PDU的报文头中携带了第二时间的信息。可选地，GTP-U中携带的该时间信息为源网络设备收到数据单元的时间信息，具体为源网络设备的SDAP层收到SDAP SDU的时刻。
目标网络设备根据如下方式确定第二时间的信息：目标网络设备根据SDAP PDU携带的第一时间的信息和两个小区/两个网络设备的定时偏差进行确定。例如：源网络设备和目标网络设备之间的定时偏差为Diff＝T_source-T_target，SDAP PDU携带的携带的第一时间的信息以源网络设备的定时为参考对应为T_source，对应的时刻为绝对时间T1。该绝对时间T1，以目标网络设备的定时为参考对应为T_target，则目标网络设备在给UE发送数据单元对应的时间信息是以目标网络设备的定时为参考的T_target对应的相对时间。例如，如图4所示的示例的一个确定时间信息的示意图，源网络设备转移过来的SDAP PDU的时间信息是用帧号和子帧号表示，例如，是帧号为frame 1，子帧号为subframe 1，对应的绝对时间为T1，而同一时刻在目标网络设备的相对时间为frame 1，子帧号为subframe 2，所以目标网络设备给UE发送的时间形式是frame 1，子帧号为subframe 2。
采用实现方式A9，可以实现有损切换。本实现方式针对的场景是源网络设备和目标网络设备在给终端设备发送数据单元时，源网络设备在GTP-U的扩展头中携带了第一时间的信息，目标网络设备在发送给UE的SDAP PDU的报文头中携带了第二时间的信息。第一时间的信息为以源网络设备定时为参考的相对时间信息，目标网络设备把第一时间信息转化为以目标网络设备定时为参考的相对时间，从而终端设备可以统一采用以当前服务小区的定时来计算数据单元对应的时延，降低了终端设备的处理复杂度。
实现方式A10、源网络设备以SDAP SDU形式转移切换的数据单元给目标网络设备。源网络设备在GTP-U的扩展头中携带了相对时间信息(第一时间的信息)，且目标网络设备在发送给UE的PDCP PDU的报文头中携带了第二时间的信息。可选地，GTP-U中携带的该时间信息为源网络设备收到数据单元的时间信息，具体为源网络设备的SDAP层收到 SDAP SDU的时刻，或者源网络设备的PDCP层收到PDCP SDU的时刻。
目标网络设备根据如下方式确定第二时间的信息：目标网络设备根据GTP-U携带的时间信息和两个小区的定时偏差进行确定。例如：源网络设备和目标网络设备之间的定时偏差为Diff＝T_source-T_target，SDAP PDU携带的第一时间的信息以源网络设备的定时为参考对应为T_source，对应的时刻为绝对时间T1。该绝对时间T1，以目标网络设备的定时为参考对应为T_target，则目标网络设备在给UE发送数据单元对应的时间信息是以目标网络设备的定时为参考的T_target对应的相对时间。例如，如图4所示的示例的一个确定时间信息的示意图，源网络设备转移过来的SDAP PDU的时间信息是用帧号和子帧号表示，例如，是帧号为frame 1，子帧号为subframe 1，对应的绝对时间为T1，而同一时刻在目标网络设备的相对时间为frame 1，子帧号为subframe 2，所以目标网络设备给UE发送的时间形式是frame 1，子帧号为subframe 2。
采用实现方式A10，可以实现有损切换。本实现方式针对的场景是源网络设备和目标网络设备在给终端设备发送数据单元时，源网络设备在GTP-U的扩展头中携带了第一时间的信息，目标网络设备在发送给UE的PDCP PDU的报文头中携带了第二时间的信息。第一时间的信息为以源网络设备定时为参考的相对时间信息，目标网络设备把第一时间信息转化为以目标网络设备定时为参考的相对时间，从而终端设备可以统一采用以当前服务小区的定时来计算数据单元对应的时延，降低了终端设备的处理复杂度。
实现方式A11、源网络设备以SDAP SDU形式转移切换的数据单元给目标网络设备。源网络设备在GTP-U的扩展头中携带了绝对时间信息(第一时间对应的绝对时间)，且目标网络设备在发送给UE的SDAP PDU的报文头中携带了第二时间的信息。可选地，GTP-U中携带的该绝对时间信息为源网络设备收到数据单元的时刻，具体为源网络设备的SDAP层收到SDAP SDU的时刻。
目标网络设备根据如下方式确定第二时间的信息：目标网络设备根据GTP-U中的绝对时间进行确定。例如：GTP-U中携带的绝对时间为T_absolute，则目标网络设备根据自身设置的绝对时间与相对时间的关系，把T_absolute设置为自身的相对时间。例如，如图5所示，T_absolute为T1，则目标网络设备知道T1绝对时间在目标网络设备对应的相对时间为frame 1,subframe 2，这样目标网络设备就知道设置相对时间为frame 1，subframe 2。
采用实现方式A11，可以实现有损切换。本实现方式针对的场景是源网络设备和目标网络设备在给终端设备发送数据单元时，源网络设备在GTP-U的扩展头中携带了第一时间的信息，目标网络设备在发送给UE的SDAP PDU的报文头中携带了第二时间的信息。第一时间的信息为绝对时间信息，目标网络设备把第一时间信息转化为以目标网络设备定时为参考的相对时间，从而终端设备可以统一采用以当前服务小区的定时来计算数据单元对应的时延，降低了终端设备的处理复杂度。
实现方式A12、源网络设备以SDAP SDU形式转移切换的数据单元给目标网络设备。源网络设备在GTP-U的扩展头中携带了绝对时间信息(第一时间对应的绝对时间)，且目标网络设备在发送给UE的PDCP PDU的报文头中携带了第二时间的信息。可选地，GTP-U中携带的该绝对时间为源网络设备收到数据单元的时刻，具体为源网络设备的SDAP层收到SDAP SDU的时刻或者源网络设备的PDCP层收到PDCP SDU的时刻。
目标网络设备根据如下方式确定第二时间的信息：目标网络设备根据GTP-U中的绝对时间进行修改。例如：GTP-U中携带的绝对时间为T_absolute，则目标网络设备根据自身设置的绝对时间与相对时间的关系，把T_absolute设置为自身的相对时间。例如，如图4所示，T_absolute为T1，则目标网络设备知道T1绝对时间在目标网络设备对应的相对时间为frame 1,subframe 2，这样目标网络设备就知道设置相对时间为frame 1，subframe 2。
采用实现方式A12，可以实现有损切换。本实现方式针对的场景是源网络设备和目标网络设备在给终端设备发送数据单元时，源网络设备在GTP-U的扩展头中携带了第一时间的信息，目标网络设备在发送给UE的PDCP PDU的报文头中携带了第二时间的信息。第一时间的信息为绝对时间信息，目标网络设备把第一时间信息转化为以目标网络设备定时为参考的相对时间，从而终端设备可以统一采用以当前服务小区的定时来计算数据单元对应的时延，降低了终端设备的处理复杂度。
实现方式A13、源网络设备以SDAP SDU形式转移切换的数据单元给目标网络设备。源网络设备在GTP-U的扩展头中携带相对时间信息(第一时间的信息)，且目标网络设备在发送给UE的SDAP PDU的报文头中携带了第二时间的信息。可选地，GTP-U中携带的该时间信息为源网络设备收到数据包的时间信息，具体为源网络设备的SDAP层收到SDAP SDU的时刻。
目标网络设备根据如下方式确定第二时间的信息：目标网络设备根据GTP-U携带的时间信息和两个小区的定时偏差进行确定。例如，如图8所示的示例的另一个确定时间信息的示意图，源网络设备和目标网络设备之间的定时偏差为Diff＝T_source-T_target，GTP-U携带的时间信息对应的时刻为T1，T1对应的绝对时间参考点是参考点1，相对时间为相对时间1(源网络设备转移给目标网络设备的GTP-U报文头中携带的相对时间信息，即第一时间的信息)。则目标网络设备在给UE发送数据时携带的时刻在绝对时间上为T1，并按照该时刻T1设置目标网络设备给UE发送的时间信息，例如，时间参考点是时间参考点2，相对时间为相对时间2。例如，目标网络设备知道源网络设备发送的绝对时间参考点的信息(即目标网络设备知道源网络设备的绝对时间参考点的时域位置)，例如，时域位置是指帧号，子帧号的位置信息，这样目标网络设备根据定时偏差知道该数据单元对应的时间参考点是哪一个，从而知道对应的绝对时间T1，目标网络设备再根据绝对时间T1获得在目标网络设备对应的绝对时间参考点2和相对时间2，之后再在给UE的SDAP PDU报文头中携带相对时间2。
采用实现方式A13，可以实现有损切换。本实现方式针对的场景是源网络设备和目标网络设备在给终端设备发送数据单元时，源网络设备在GTP-U的扩展头中携带了第一时间的信息，目标网络设备在发送给UE的SDAP PDU的报文头中携带了第二时间的信息。第一时间的信息为以源网络设备定时为参考的相对时间信息，目标网络设备把第一时间信息转化为以目标网络设备定时为参考的相对时间，从而终端设备可以统一采用以当前服务小区的定时来计算数据单元对应的时延，降低了终端设备的处理复杂度。
实现方式A14、源网络设备通过SDAP SDU转移切换的数据单元给目标网络设备。源网络设备在GTP-U的扩展头中携带了相对时间信息(第一时间的信息)，且目标网络设备在发送给UE的PDCP PDU的报文头中携带了第二时间的信息。
目标网络设备根据如下方式确定第二时间的信息：目标网络设备根据GTP-U携带的相对时间信息和两个小区的定时偏差进行确定。例如，源网络设备和目标网络设备之间的定时偏差为Diff＝T_source-T_target(这里的定时偏差是绝对时间的偏差)，GTP-U的扩展头携带的时间信息对应的时刻为T1，T1对应的绝对时间参考点是参考点1，相对时间为相对时间1(源网络设备转移给目标网络设备的GTP-U的扩展头中携带的相对时间信息)，则目标网络设备在给UE发送数据时携带的时刻在绝对时间上为T1,并按照该时刻T1设置目标网络设备给UE发送的时间信息，例如，时间参考点是时间参考点2，相对时间为相对时间2。例如，目标网络设备知道源网络设备发送的绝对时间参考点的信息(即目标网络设备知道源网络设备的绝对时间参考点的时域位置)，例如，时域位置是指帧号，子帧号的位置信息。这样目标网络设备根据定时偏差知道该数据单元对应的时间参考点是哪一个，从而知道对应的绝对时间T1，目标网络设备再根据绝对时间T1获得在目标网络设备对应的绝对时间参考点2和相对时间2，之后再在给UE的PDCP PDU报文头中携带相对时间2。
采用实现方式A14，可以实现有损切换。本实现方式针对的场景是源网络设备和目标网络设备在给终端设备发送数据单元时，源网络设备在GTP-U的扩展头中携带了第一时间的信息，目标网络设备在发送给UE的PDCP PDU的报文头中携带了第二时间的信息。第一时间的信息为以源网络设备定时为参考的相对时间信息，目标网络设备把第一时间信息转化为以目标网络设备定时为参考的相对时间，从而终端设备可以统一采用以当前服务小区的定时来计算数据单元对应的时延，降低了终端设备的处理复杂度。
实现方式A15、源网络设备以SDAP SDU形式转移切换的数据单元给目标网络设备。源网络设备在GTP-U的扩展头中携带了绝对时间和相对时间信息，或者绝对时间信息，且目标网络设备在发送给UE的SDAP PDU的报文头中携带了修改后的时间信息。
目标网络设备根据如下方式确定第二时间的信息：目标网络设备根据GTP-U中携带的绝对时间(第一时间)设置目标网络设备给UE发送的绝对时间和相对时间(第二时间)。例如：GTP-U中携带的绝对时间为T1，则目标网络设备根据该绝对时间T1设置给UE发送的绝对时间和相对时间。例如，在目标网络设备中绝对时间T1对应的时间参考为绝对时间参考2，相对时间为相对时间2。
采用实现方式A16，可以实现有损切换。本实现方式针对的场景是源网络设备和目标网络设备在给终端设备发送数据单元时，源网络设备在GTP-U的扩展头中携带了第一时间的信息，目标网络设备在发送给UE的SDAP PDU的报文头中携带了第二时间的信息。第一时间的信息为绝对时间信息和相对时间信息，或绝对时间信息，目标网络设备把第一时间信息转化为以目标网络设备定时为参考的绝对时间和相对时间，从而终端设备可以统一采用以当前服务小区的定时来计算数据单元对应的时延，降低了终端设备的处理复杂度。
实现方式A16、源网络设备以SDAP SDU形式转移切换的数据单元给目标网络设备。源网络设备在GTP-U的扩展头中携带了绝对时间和相对时间信息，或者绝对时间信息，且目标网络设备在发送给UE的PDCP PDU的报文头中携带了第二时间的信息。
目标网络设备根据如下方式确定第二时间的信息：目标网络设备根据GTP-U中携带的绝对时间设置目标网络设备给UE发送的绝对时间和相对时间。例如：GTP-U中携带的绝对时间为T1，则目标网络设备根据该绝对时间T1设置给UE发送的绝对时间和相对时间。 例如，在目标网络设备中绝对时间T1对应的时间参考为绝对时间参考2，相对时间为相对时间2。
采用实现方式A16，可以实现有损切换。本实现方式针对的场景是源网络设备和目标网络设备在给终端设备发送数据单元时，源网络设备在GTP-U的扩展头中携带了第一时间的信息，目标网络设备在发送给UE的PDCP PDU的报文头中携带了第二时间的信息。第一时间的信息为绝对时间信息和相对时间信息，或者绝对时间信息，目标网络设备把第一时间信息转化为以目标网络设备定时为参考的相对时间和绝对时间，从而终端设备可以统一采用以当前服务小区的定时来计算数据单元对应的时延，降低了终端设备的处理复杂度。
具体实现中，在上述实施例中，UE作为发送端设备，由UE确定第二时间的信息。UE在向目标网络设备发送没有被源网络设备正确接收的数据单元或者已经按照源网络设备的格式设置时间信息的数据单元时，UE考虑这些数据单元在UE侧的等待时间。例如，UE按照源网络设备和目标网络设备之间的时间偏差，以及该数据单元对应的第一时间的信息，转换为目标网络设备的第二时间的信息。具体包括如下A17和A18两种实现方式：
实现方式A17、UE根据数据单元对应的第一时间的信息以及源网络设备和目标网络设备之间的定时偏差，把原先的时刻(第一时间)以目标网络设备的相对时间(第二时间)的形式表示。第一时间和第二时间是以相对时间的形式表示，比如帧号，子帧号等。例如，如图4所示，原先的时间信息是帧号为frame 1，子帧号为subframe 1，对应的时刻为T1，而同一时刻目标网络设备的相对时间为frame 1，子帧号为subframe 2。
采用实现方式A17，本实现方式针对的场景是终端设备给源网络设备和目标网络设备发送数据单元时，终端设备给目标网络设备发送了第二时间的信息。第一时间的信息为以源网络设备定时为参考的相对时间信息，终端设备把第一时间信息转化为以目标网络设备定时为参考的相对时间，从而目标网络设备可以统一采用以当前服务小区的定时来计算数据单元对应的时延，降低了目标网络设备的处理复杂度。
实现方式A18、UE根据数据单元对应的第一时间的信息以及源网络设备和目标网络设备之间的定时偏差，把原先的时刻(第一时间)以目标网络设备的相对时间(第二时间)的形式表示。第一时间和第二时间是以绝对时间和相对时间的形式表示，比如以某个帧对应的绝对时间作为参考点，相对时间是相对于该帧的时间偏移。例如，如图7所示，第一时间在源网络设备对应的参考点为为帧号为frame 1下发的绝对时间，第一时间中的相对时间为相对于frame 1的时间偏移T2，第一时间对应的时刻在目标网络设备对应的参考点为为帧号为frame 2下发的绝对时间，第二时间中的相对时间为相对于frame 1的时间偏移T3。
采用实现方式A18，本实现方式针对的场景是终端设备给源网络设备和目标网络设备发送数据单元时，终端设备给目标网络设备发送了第二时间的信息。第一时间的信息为以源网络设备定时为参考的相对时间信息和绝对时间信息，终端设备把第一时间信息转化为以目标网络设备定时为参考的相对时间和绝对时间，从而目标网络设备可以统一采用以当前服务小区的定时来计算数据单元对应的时延，降低了目标网络设备的处理复杂度。
图9为本申请实施例提供的另一种通信方法的流程示意图，该方法包括以下步骤：
S901、目标网络设备获取数据单元对应的第一时间的信息。
在上行传输过程中，如果发生小区切换，源网络设备需要将从UE接收到的乱序的数据单元转移到目标网络设备。乱序是指在源网络设备从UE正确接收到的数据单元之前的一些数据单元并没有被源网络设备正确接收。例如，接收到了packet2和packet3，但还没接收到packet1。则源网络设备将packet2和packet3发送给目标网络设备。
在一个实现方式中，目标网络设备可以从源网络设备接收所述数据单元对应的第一时间的信息。
在另一个实现方式中，目标网络设备也可以从PDCP层获取所述数据单元对应的第一时间的信息。
可选地，源网络设备向目标网络设备发送接收到的数据单元。目标网络设备接收该数据单元，获取该数据单元携带的第一时间的信息。该第一时间指示源网络设备接收数据单元的第一时刻。该第一时间是以源网络设备的定时作为参考的。
可选地，源网络设备向目标网络设备发送接收到的数据单元，源网络设备向目标网络设备发送该数据单元对应的第一时间的信息。目标网络设备接收该数据单元，获取该数据单元对应的第一时间的信息。该第一时间指示源网络设备接收数据单元的第一时刻。该第一时间是以源网络设备的定时作为参考的，或者第一时间是源网络设备接收数据单元的绝对时间。
可选地，源网络设备向目标网络设备发送接收到的数据单元，源网络设备向目标网络设备发送该数据单元对应的第一时间的信息。目标网络设备接收该数据单元，获取该数据单元对应的第一时间的信息。该第一时间指示UE在源网络设备发送该数据单元对应的第一时刻，或者指示UE的无线协议层(比如SDAP或PDCP层)从上层(比如应用层或IP层)收到该数据单元的时刻，或者UE的无线协议层(比如SDAP或PDCP层)向下一层发送该数据单元的时刻，或者UE的无线协议层(比如SDAP或PDCP层)从上层(比如应用层或IP层)收到该数据单元与UE的无线协议层(比如SDAP或PDCP层)向下一层发送该数据单元的时刻之间的任何一个时刻。该第一时间是以源网络设备的定时作为参考的。
S902、所述目标网络设备确定所述数据单元对应的第二时间的信息。
目标网络设备要将从源网络设备接收到的数据包发送给核心网设备，为了准确地获得从UE接收到数据包的时延，目标网络设备需要确定目标网络设备从UE接收到数据包的时刻，即第二时间。
可选地，当第一时间是以源网络设备的定时作为参考的，目标网络设备可以根据上述第一时间的信息和定时偏差，确定第二时间的信息。其中，所述第二时间是所述源网络设备接收到所述数据包的时刻。所述第二时间是以所述目标网络设备的定时作为参考的。
UE可以是在不同的小区或不同的网络设备之间切换。因此，定时偏差包括以下至少一种：目标网络设备与源网络设备的定时偏差、目标网络设备与源网络设备的定时偏差。
可选地，当第一时间是源网络设备接收数据单元的绝对时间，目标网络设备可以根据上述第一时间的信息和目标网络设备中目标网络设备的绝对时间与相对时间的关系，确定第二时间的信息。其中，所述第二时间是所述源网络设备接收到所述数据单元的时刻。所 述第二时间是以所述目标网络设备的定时作为参考的。
可选地，目标网络设备还可以根据第一时间的信息确定第二时间的信息，其中，所述第二时间是所述源网络设备接收到所述数据单元的时刻对应的绝对时间。
S903、所述目标网络设备根据所述第二时间的信息和发送所述数据单元的时刻，确定所述数据单元的时延信息。
目标网络设备根据第二时间和向核心网设备提交数据单元对应的数据包的时刻，这两个时刻的差别即为数据包的时延。
可选地，所述发送所述数据单元的时刻是指目标网络设备发送所述数据单元中的数据包给核心网的时刻，或者目标网络设备的SDAP层发送所述数据单元中的数据包给PDCP层的时刻，或者目标网络设备的PDCP层发送所述数据单元中的数据包给SDAP层的时刻。
可选地，所述方法还包括：向网管系统发送所述时延信息。该网管系统是根据运营商的要求，对网络的传输效率等进行监测。目标网络设备向网管系统发送时延信息，从而运营商可以根据该时延信息，对网络进行优化。
根据本申请实施例提供的一种通信方法，在上行数据传输过程中，第一时间信息为以源网络设备定时为参考的时间信息，目标网络设备把该第一时间的信息转换为以目标网络设备定时为参考的第二时间的信息，从而终端设备可以统一采用当前服务小区的定时，降低了终端设备的处理复杂度。
具体实现中，在上述实施例中，在上行传输过程中，可以由目标网络设备补偿从源网络设备转移到目标基站所需的时间，或者统一第一时间和第二时间的形式，并计算出时延。包括如下实现方式A19～A25。需要说明的是，只有在无损切换下才会进行上行转移。
实现方式A19、源网络设备以SDAP PDU或PDCP SDU形式转移切换的数据单元给目标网络设备。源网络设备在SDAP PDU的报文头中携带了相对时间信息，目标网络设备计算时延。目标网络设备根据如下方式计算时延：目标网络设备根据SDAP PDU携带的时间信息和两个小区的定时偏差进行补偿。例如，源网络设备和目标网络设备之间的定时偏差为Diff＝T_source-T_target，SDAP PDU携带的时间信息对应的时刻为T1，T1对应在源网络设备的相对时间表现形式为源网络设备的帧号frame 1，子帧号为subframe 1，假设目标网络设备的SDAP层把数据包提交给上层(比如核心网)的时刻为T2,T2对应在目标网络设备的相对时间表现形式为目标网络设备的帧号frame 1，子帧号为subframe 3，则目标网络设备计算时延时，先根据两个小区的定时偏差把T1时刻对应的源网络设备的帧号frame1，子帧号为subframe 1转换为T1时刻对应目标网络设备的帧号frame1,子帧号subframe2，目标网络设备根据目标网络设备的帧号frame1,子帧号subframe2和目标网络设备的帧号frame 1,子帧号为subframe 3计算对应的时延。例如，SDAP PDU的时间信息是对应帧号为frame 1，子帧号为subframe 1，对应的时刻为T1，而同一时刻在目标网络设备的相对时间为frame 1，子帧号为subframe 2，而目标网络设备SDAP层把数据包提交给上层的时刻为frame 3，子帧号为subframe 3。则时延为(frame 3-frame 1)*10ms+(subframe 3-subfram 2)*1ms。
采用实现方式A19，可应用于上行切换传输场景中，源网络设备以SDAP PDU或PDCP SDU形式转移切换的数据单元给目标网络设备，源网络设备在SDAP PDU的报文头中携带 了第一时间的信息，该第一时间为相对时间，目标网络设备根据第一时间的信息和定时偏差，确定第二时间的信息，从而可以统一采用以当前服务小区的定时作为参考计算时延。
实现方式A20、源网络设备以SDAP PDU或PDCP SDU形式转移切换的数据单元给目标网络设备。源网络设备在GTP-U的扩展头中携带了相对时间信息，目标网络设备计算时延。目标网络设备根据如下方式计算时延：目标网络设备根据GTP-U携带的时间信息和两个小区的定时偏差进行补偿。例如，源网络设备和目标网络设备之间的定时偏差为Diff＝T_source-T_target，GTP-U携带的时间信息对应的时刻为T1，T1对应在源网络设备的相对时间表现形式为源网络设备的帧号frame 1,子帧号为subframe 1，假设目标网络设备的SDAP层把数据单元中的数据包提交给上层的时刻为T2,T2对应在目标网络设备的相对时间表现形式为目标网络设备的帧号frame 1,子帧号为subframe 3，则目标网络设备计算时延时，先把T1时刻对应的源网络设备的帧号frame1，子帧号为subframe 1根据两个小区的定时偏差转换为T1时刻对应目标网络设备的帧号frame1,子帧号subframe2，目标网络设备根据目标网络设备的帧号frame1,子帧号subframe2和目标网络设备的帧号frame 1,子帧号为subframe 3计算对应的时延。例如，SDAP PDU的时间信息是对应帧号为frame 1，子帧号为subframe 1，对应的时刻为T1，而同一时刻在目标网络设备的相对时间为frame 1，子帧号为subframe 2，而目标网络设备SDAP层把数据包提交给上层的时刻为frame 3，子帧号为subframe 3。则时延为(frame 3-frame 1)*10ms+(subframe 3-subframe 2)*1ms。
采用实现方式A20，可应用于上行切换传输场景中，源网络设备以SDAP PDU或PDCP SDU形式转移切换的数据单元给目标网络设备，源网络设备在GTP-U的扩展头中携带了第一时间的信息，该第一时间为相对时间，目标网络设备根据第一时间的信息和定时偏差，确定第二时间的信息，从而可以统一采用以当前服务小区的定时作为参考计算时延。
实现方式A21、源网络设备以SDAP PDU或PDCP SDU形式转移切换的数据单元给目标网络设备。源网络设备在GTP-U的扩展头中携带了绝对时间和该数据单元的时延信息，目标网络设备计算时延。该绝对时间为源网络设备收到数据包的时刻，具体为源网络设备的PDCP层收到PDCP SDU的时刻。该时延信息为源网络设备计算出的该数据包从UE发送到源网络设备接收的时延。目标网络设备根据如下方式计算时延：目标网络设备根据GTP-U携带的绝对时间、该数据单元的时延信息、以及该数据单元对应的数据包在目标网络设备中提交给上层时所需时间计算出对应的时延。例如，目标网络设备的PDCP层把包提交给上层的绝对时间为T2，GTP-U携带的绝对时间为T1，该数据单元从UE侧发送到源网络设备接收到该包的时延为Delay_source，则该包的总时延为：T2-T1+Delay_source。
采用实现方式A21，可应用于上行切换传输场景中，源网络设备以SDAP PDU或PDCP SDU形式转移切换的数据单元给目标网络设备，源网络设备在GTP-U的扩展头中携带了第一时间的信息，该第一时间为绝对时间，目标网络设备根据第一时间的信息和定时偏差，确定第二时间的信息，从而可以统一采用以当前服务小区的定时作为参考计算时延。
实现方式A22、源网络设备以SDAP PDU或PDCP SDU形式转移切换的数据单元给目标网络设备。源网络设备在SDAP PDU的报文头中携带了相对时间信息，目标网络设备计算时延。目标网络设备根据如下方式计算时延：目标网络设备根据SDAP PDU携带的相对时间信息和两个小区的定时偏差进行补偿。例如，源网络设备和目标网络设备之间的定时 偏差为Diff＝T_source-T_target，GTP-U的扩展头携带的时间信息对应的时刻为T1，T1对应的绝对时间参考点是参考点1，相对时间为相对时间1(源网络设备转移给目标网络设备的SDAP PDU的报文头中携带的相对时间信息)，则目标网络设备可以计算T1在目标网络设备对应的绝对时间参考点2和相对时间2。例如，目标网络设备知道源网络设备发送的绝对时间参考点的信息(即目标网络设备知道源网络设备的绝对时间参考点的时域位置)，例如，时域位置是指帧号，子帧号的位置信息。这样目标网络设备根据定时偏差知道该包对应的时间参考点是哪一个，从而知道对应的绝对时间T1，目标网络设备再根据绝对时间T1获得在目标网络设备对应的绝对时间参考点2和相对时间2，之后根据目标网络设备的SDAP层把包提交给上层的绝对时间为T2(在目标网络设备对应的绝对时间参考点2和相对时间3)和绝对时间T1(在目标网络设备对应的绝对时间参考点2和相对时间2)计算时延。
采用实现方式A22，可应用于上行切换传输场景中，源网络设备以SDAP PDU或PDCP SDU形式转移切换的数据单元给目标网络设备，源网络设备在SDAP PDU的报文头中携带了第一时间的信息，该第一时间为相对时间，目标网络设备根据第一时间的信息和定时偏差，确定第二时间的信息，从而可以统一采用以当前服务小区的定时作为参考计算时延。
实现方式A23、源网络设备以SDAP PDU或PDCP SDU形式转移切换的数据单元给目标网络设备。源网络设备在GTP-U的扩展头中携带了绝对时间，SDAP PDU中携带了相对时间。目标网络设备根据如下方式计算时延：根据GTP-U中携带的绝对时间和SDAP PDU中携带的相对时间进行计算。例如，目标网络设备把SDAP SDU提交给上层的时刻为T2，GTP-U中携带的绝对时间和SDAP PDU中携带的相对时间对应的时刻为T1，则时延为T2-T1。
采用实现方式A23，可应用于上行切换传输场景中，源网络设备以SDAP PDU或PDCP SDU形式转移切换的数据单元给目标网络设备，源网络设备在GTP-U的扩展头中携带了第一时间的信息，该第一时间为绝对时间，目标网络设备根据第一时间的信息和定时偏差，确定第二时间的信息，从而可以统一采用以当前服务小区的定时作为参考计算时延。
实现方式A24、源网络设备以SDAP PDU或PDCP SDU形式转移切换的数据单元给目标网络设备。源网络设备在GTP-U的扩展头中携带了绝对时间信息，或者绝对时间和相对时间的信息。目标网络设备根据如下方式计算时延：根据GTP-U携带的绝对时间计算时延。例如，假设目标网络设备的PDCP层把数据包提交给上层的绝对时间时刻为T2，GTP-U携带的绝对时间信息对应的时刻为T1，则时延为T2-T1。
采用实现方式A24，可应用于上行切换传输场景中，源网络设备以SDAP PDU或PDCP SDU形式转移切换的数据单元给目标网络设备，源网络设备在SDAP PDU的报文头中携带了第一时间的信息，该第一时间为绝对时间，或者绝对时间和相对时间，目标网络设备根据第一时间的信息和定时偏差，确定第二时间的信息，从而可以统一采用以当前服务小区的定时作为参考计算时延。
实现方式A25、源网络设备以SDAP PDU或PDCP SDU形式转移切换的数据单元给目标网络设备。源网络设备在GTP-U的扩展头中携带了绝对时间和该数据包的时延信息。该绝对时间为源网络设备收到数据单元的时刻，具体为源网络设备的PDCP层收到PDCP SDU的时刻。该时延信息为源网络设备计算出的该数据包从终端发送到源网络设备接收的时延。 目标网络设备根据如下方式计算时延：根据GTP-U携带的绝对时间+该包的时延信息+该包在目标网络设备中提交给上层时所需时间计算出对应的时延。例如，目标网络设备的PDCP层把包提交给上层的绝对时间为T2，GTP-U携带的绝对时间为T1，该包在源网络设备的时延为Delay_source，则该包的总时延为：T2-T1+Delay_source。
采用实现方式A25，可应用于上行切换传输场景中，源网络设备以SDAP PDU或PDCP SDU形式转移切换的数据单元给目标网络设备，源网络设备在GTP-U的扩展头中携带了第一时间的信息，该第一时间为绝对时间，目标网络设备根据第一时间的信息和定时偏差，确定第二时间的信息，从而可以统一采用以当前服务小区的定时作为参考计算时延。
图10为本申请实施例提供的又一种通信方法的流程示意图，该方法包括以下步骤：
S1001、接收端设备获取数据单元对应的第一时间的信息。
该方法可应用于下行切换传输或UE发送数据单元等场景中。
可选地，在下行切换传输过程中，在S1001之前，还包括步骤：发送端设备向接收端设备发送数据单元，相应的，接收端设备接收该数据单元。
其中，该第一时间以源网络设备的定时作为参考。
在一个实现方式中，所述接收端设备获取数据单元对应的第一时间的信息，包括：所述接收端设备从发送端设备接收所述数据单元对应的第一时间的信息。
可选地，所述接收端设备为终端设备，所述发送端设备为目标网络设备，所述方法还包括：所述接收端设备接收来自所述发送端设备的第一指示，所述第一指示用于指示所述数据单元为从所述源网络设备转移至所述目标网络设备的数据单元。
具体实现中，在下行数据传输过程中，如果UE发生移动，例如，从源网络设备移动到目标网络设备，源网络设备需要把从核心网接收到的且还没被UE正确接收的下行数据转移到目标网络设备。源网络设备向目标网络设备发送切换时转移的数据单元时，同时发送一个第一时间的信息。该第一时间对应的时刻同S201中发送端设备为目标网络设备时对应的第一时间，第一时间以源网络设备的定时作为参考。
目标网络设备接收源网络设备发送的数据单元，并向终端设备发送该数据单元。目标网络设备接收源网络设备发送的该数据单元对应的第一时间的信息，并向UE发送该第一时间的信息。同时，还向终端设备发送第一指示。其中，该第一指示用于指示数据单元为从源网络设备转移至目标网络设备的数据单元。可选地，该第一指示也可以包括在该数据单元中，该第一指示也可以包括在该数据单元对应的SDAP或PDCP PDU的报头中。可选地，该第一指示还可以为一个的控制数据单元，该控制数据单元之前的数据单元都是从源网络设备转移至目标网络设备的数据单元，该控制包之后的数据单元都不是从源网络设备转移至目标网络设备的数据单元。
在另一个实现方式中，接收端设备获取数据单元对应的第一时间的信息，包括：所述接收端设备从PDCP层获取所述数据单元对应的第一时间的信息。具体实现中，接收端设备的PDCP层从目标网络设备获取数据单元，该第一时间为接收端设备的其它协议栈层在进行后续处理过程中，从PDCP层获取数据单元对应的时间。在UE发送数据单元的场景中，UE记录向源网络设备发送数据单元的时刻，即第一时间。该第一时间同S201中发送 端设备为终端设备时对应的第一时间，是以源网络设备的定时作为参考的。然而，UE向源网络设备发送数据单元并未成功，且此时，UE发生了小区切换，UE需要向目标网络设备发送该数据单元。其中，终端设备向目标网络设备发送所述数据单元对应的第一时间的信息。所述第一时间是以所述源网络设备的定时作为参考的。同时，终端设备还向目标网络设备发送第一指示。所述第一指示用于指示所述数据单元为所述终端设备发送的数据单元，或者为所述终端设备在切换过程中发送的数据单元，或者为所述所述数据单元对应的第一时间的信息是以所述源网络设备的定时作为参考的。可选地，所述第一指示也可以携带在所述数据单元中。可选地，所述第一时间的信息携带在所述数据单元中。该第一指示也可以包括在该数据单元对应的SDAP或PDCP PDU的报头中。可选地，该第一指示还可以为一个的控制数据单元，该控制数据单元之前的数据单元都是从源网络设备转移至目标网络设备的数据单元，该控制数据单元之后的数据单元都不是从源网络设备转移至目标网络设备的数据单元，或该控制数据单元代表从源网络设备转移至目标网络设备的数据单元的结束。
S1002、所述接收端设备根据所述第一时间的信息、定时偏差、以及所述接收端设备接收到所述数据单元的第二时间的信息，确定所述接收端设备获取所述数据单元的时延信息。
在下行切换传输的场景中，终端设备从目标网络设备接收所述数据单元和所述第一指示。终端设备同时从目标网络设备接收该数据单元对应的第一时间的信息。如果第一指示指示该数据单元为从源网络设备转移至目标网络设备的数据单元，终端设备根据所述第一时间的信息、定时偏差、以及所述终端设备接收到所述数据单元的第二时间的信息，计算所述终端设备接收到所述数据单元的时延信息。其中，定时偏差包括以下至少一种：目标网络设备与源网络设备的定时偏差、目标网络设备与源网络设备的定时偏差。
可选地，第二时间是指UE成功接收到所述数据单元的时刻，或者UE的无线协议层(比如SDAP或PDCP层)把该数据单元的数据包提交给上层(比如应用层或IP层)的时刻，或者UE的无线协议层(比如PDCP层)把该数据单元的数据包向上一个无线协议层(比如SDAP层)的时刻，或者UE的无线协议层(比如SDAP或PDCP层)收到该数据单元的时刻到把该数据单元的数据包提交给上一层的时刻之间的任何一个时刻。
可选地，所述方法还包括以下步骤：
所述接收端设备向所述目标网络设备发送所述时延信息。
终端设备计算出时延后，向目标网络设备发送该时延信息。目标网络设备接收该时延信息，可以了解目标网络设备下行传输给终端设备的时延。
在UE发送数据单元的场景中，可选地，所述第二时间是以所述目标网络设备的定时作为参考的。目标网络设备从所述终端设备接收所述数据单元和所述第一指示。接收所述数据单元对应的第一时间的信息。目标网络设备根据所述第一时间的信息、定时偏差和接收到所述发送的数据单元的第二时间的信息，可以确定接收到所述发送的数据单元的时延信息。其中，定时偏差包括以下至少一种：目标网络设备与源网络设备的定时偏差、目标网络设备与源网络设备的定时偏差。
可选地，第二时间是指目标网络设备成功接收到所述数据单元的时刻，或者目标网络设备的无线协议层(比如SDAP或PDCP层)把该数据单元的数据包提交给上层(比如应 用层或IP层或核心网)的时刻，或者目标网络设备的无线协议层(比如PDCP层)把该数据单元的数据包向上一个无线协议层(比如SDAP层)的时刻，或者目标网络设备的无线协议层(比如SDAP或PDCP层)收到该数据单元的时刻到把该数据单元的数据包提交给上一层的时刻之间的任何一个时刻。
可选地，目标网络设备还可能把第一时间的信息和第二时间的信息转换为其他统一的时间形式来计算该数据单元的时延，比如都转换为源网络设备为参考的时间，或者绝对时间等。
可选地，所述方法还包括：向网管系统发送所述时延信息。该网管系统是根据运营商的要求，对网络的传输效率等进行监测。目标网络设备向网管系统发送时延信息，从而运营商可以根据该时延信息，对网络进行优化。
根据本申请实施例提供的一种通信方法，在下行数据传输过程中，第一时间信息为以源网络设备定时为参考的时间信息，接收端设备把该第一时间的信息转换为以目标网络设备定时为参考的时间的信息，从而可以统一采用当前服务小区的定时来计算时延。
具体实现中，在上述实施例中，在下行传输过程中，终端设备作为接收端设备，由终端设备修改时间信息。可以包括如下B1～B8等多种实现方式：
实现方式B1、源网络设备以SDAP PDU/PDCP SDU形式转移切换的数据单元给目标网络设备。源网络设备转移SDAP PDU/PDCP SDU,SDAP PDU中携带了相对时间信息(时间信息为帧号、子帧号等)，目标网络设备在发送给UE的SDAP PDU的报文头中携带时间信息。UE根据如下方式计算时延：UE根据源网络设备和目标网络设备的时间偏差进行转换SDAP PDU中携带的时间信息。例如：UE发现该数据单元为从源网络设备转移到目标网络设备的数据单元，则UE知道其中携带的时间信息是以源网络设备为参考的，则UE可以根据源网络设备和目标网络设备之间的时间偏差来计算出该携带的时间信息对应的目标网络设备的相对时间。例如，SDAP PDU的时间信息是对应帧号为frame 1,子帧号为subframe 1，对应的时刻为T1，UE可以根据两个小区的时间偏差知道同一时刻在目标网络设备的相对时间为frame 1,子帧号为subframe 2。之后UE再根据SDAP层把该包提交给上层的时刻与SDAP PDU中携带的时间信息转换为目标网络设备的相对时间之间的差值作为该包的时延。可选的，UE还可能把SDAP PDU中携带的时间信息和UE把包提交给上层的时刻转换为其他统一的形式来计算该包的时延，比如都转换为源网络设备为参考的时间，或者绝对时间等。
如图11所示的示例的接收端设备确定第二时间的信息的流程示意图。该方法包括以下步骤：
S1101、在下行切换传输过程中，目标网络设备获取数据单元对应的第一时间的信息。
例如，第一时间T1是以源网络设备的定时作为参考，具体为帧1，子帧1。
具体地，目标网络设备可以是从源网络设备获取该第一时间的信息，也可以是从上一个协议层获取该第一时间的信息。
可选地，目标网络设备还从源网络设备接收该数据单元。
S1102、所述目标网络设备向终端设备发送所述第一时间的信息。
可选地，所述目标网络设备还向所述终端设备发送所述数据单元。
S1103、所述终端设备确定所述数据单元对应的第二时间的信息，并根据所述第二时间的信息和接收到所述数据单元的第三时间的信息，确定时延信息。
其中，第二时间以目标网络设备的定时作为参考，第二时间具体为帧1，子帧2。
第三时间T2以目标网络设备的定时作为参考，T2为帧1，子帧3。
终端设备统一以目标网络设备的定时作为参考，则确定时延＝T2-T1。即时延＝(帧1，子帧3)-(帧1，子帧2)＝一个子帧。
S1104、终端设备向目标网络设备发送该时延信息。
以上S1101～S1104为下行切换传输过程。与下面的终端设备发送数据单元的过程可以是独立的。
S1105、在终端设备发送数据单元的过程中，例如终端设备重传数据单元给目标网络设备的过程中，终端设备获取数据单元对应的第一时间信息。
例如，UE向源网络设备发送数据单元的第一时间T3，以源网络设备的定时作为参考，则T3为帧2，子帧1。
S1106、所述终端设备向所述目标网络设备发送所述第一时间的信息。
S1107、所述目标网络设备确定第二时间的信息，并根据第二时间的信息和接收到所述数据单元的第三时间的信息，确定时延信息。
UE根据第一时间的信息和定时偏差，确定以目标网络设备的定时作为参考的第一时间T3为帧2，子帧2。
例如，目标网络设备接收到数据单元的第三时间T4，以目标网络设备的定时作为参考，T4为帧2，子帧3，则时延＝T4-T3＝(帧2，子帧3)-(帧2，子帧4)＝一个子帧。
实现方式B2、源网络设备以SDAP PDU/PDCP SDU形式转移切换的数据单元给目标网络设备。源网络设备转移SDAP PDU，并在GTP-U的扩展头中携带了时间信息(时间信息为帧号、子帧号等)，且目标网络设备把GTP-U中携带的时间信息增加到PDCP PDU中。GTP-U中携带的该时间信息为源网络设备收到数据包的时间信息。UE根据如下方式计算时延：UE根据源网络设备和目标网络设备的时间偏差进行转换PDCP PDU中携带的时间信息。例如：UE发现该数据单元为从源网络设备转移至目标网络设备的数据单元，则UE知道其中携带的时间信息是以源网络设备为参考的，则UE可以根据源网络设备和目标网络设备之间的时间偏差来计算出该携带的时间信息对应的目标网络设备的相对时间。举例：PDCP PDU的时间信息是对应帧号为frame 1,子帧号为subframe 1，对应的时刻为T1，UE可以根据两个小区的时间偏差知道同一时刻在目标网络设备的相对时间为frame 1,子帧号为subframe 2。之后UE再根据PDCP层把该包提交给上层的时刻与PDCP PDU中携带的时间信息转换为目标网络设备的相对时间之间的差值作为该包的时延。可选的，UE还可能把PDCP PDU中携带的时间信息和UE把包提交给上层的时刻转换为其他统一的形式来计算该包的时延，比如都转换为源网络设备为参考的时间，或者绝对时间等。
实现方式B3、源网络设备以SDAP PDU/PDCP SDU形式转移切换的数据单元给目标网络设备。源网络设备转移SDAP PDU，并在SDAP PDU中携带了相当于源网络设备中一个绝对时间的时间偏移，即相对时间信息，且目标网络设备把GTP-U中携带的相对时间信息 增加到SDAP PDU中携带。GTP-U中携带的时间信息代表源网络设备收到数据包的时刻，具体为源网络设备的SDAP层收到SDAP SDU的时刻。UE根据如下方式计算时延：UE根据源网络设备和目标网络设备的时间偏差进行转换SDAP PDU中携带的时间信息。例如：UE发现该数据单元为从源网络设备转移至目标网络设备的数据单元，则UE知道其中携带的时间信息是以源网络设备为参考的，则UE可以根据源网络设备和目标网络设备之间的时间偏差来计算出该携带的时间信息对应的目标网络设备的相对时间。举例：UE发现该数据单元为从源网络设备转移至目标网络设备的数据单元，则可以获知源网络设备的绝对时间T1，SDAP PDU中的相对时间是以源网络设备的绝对时间T1作为参考的，所以这个数据单元的起始时间为：T1+SDAP PDU携带的相对时间。UE SDAP层把该数据单元提交给上层的时刻为目标网络设备的绝对时间T2,则该包的时延为T2-(T1+SDAP PDU携带的相对时间)。
实现方式B4、源网络设备以SDAP PDU/PDCP SDU形式转移切换的数据单元给目标网络设备。源网络设备转移SDAP PDU，并在GTP-U的扩展头中携带了相当于源网络设备中一个绝对时间的时间偏移，即相对时间信息，且目标网络设备把GTP-U中携带的相对时间信息增加到PDCP PDU中携带。GTP-U中携带的该绝对时间为源网络设备收到数据包的时刻，具体为源网络设备的PDCP层收到PDCP SDU的时刻。UE根据如下方式计算时延：UE根据源网络设备和目标网络设备的时间偏差进行转换PDCP PDU中携带的时间信息。例如：UE发现该数据单元为从源网络设备转移至目标网络设备的数据单元，则UE知道其中携带的时间信息是以源网络设备为参考的，则UE可以根据源网络设备和目标网络设备之间的时间偏差来计算出该携带的时间信息对应的目标网络设备的相对时间。举例：UE发现该数据单元为从源网络设备转移至目标网络设备的数据单元，则可以获知源网络设备的绝对时间T1，PDCP PDU中的相对时间是以源网络设备的绝对时间T1作为参考的，所以这个数据单元的起始时间为：T1+PDCP PDU携带的相对时间。UE PDCP层把该数据单元提交给上层的时刻为目标网络设备的绝对时间T2,则该数据单元的时延为T2-(T1+PDCP PDU携带的相对时间)。
实现方式B5、源网络设备以SDAP SDU形式转移切换的数据单元给目标网络设备。源网络设备在GTP-U的扩展头中携带相对时间信息(时间信息为帧号、子帧号等)，目标网络设备在发送给UE的SDAP PDU的报文头中携带时间信息。UE根据如下方式计算时延：同B1。
实现方式B6、源网络设备以SDAP SDU形式转移切换的数据单元给目标网络设备。源网络设备转移SDAP SDU，并在GTP-U的扩展头中携带了时间信息(时间信息为帧号、子帧号等)，且目标网络设备把GTP-U中携带的时间信息增加到PDCP PDU中。GTP-U中携带的该时间信息为源网络设备收到数据包的时间信息。UE根据如下方式UE根据如下方式计算时延：同B2。
实现方式B7、源网络设备以SDAP SDU形式转移切换的数据单元给目标网络设备。源网络设备转移SDAP SDU，并在GTP-U的扩展头中携带了相当于源网络设备中一个绝对时间的时间偏移，即相对时间信息，且目标网络设备把GTP-U中携带的相对时间信息增加到SDAP PDU中。GTP-U中携带的时间信息代表源网络设备收到数据包的时刻，具体为源网 络设备的SDAP层收到SDAP SDU的时刻。UE根据如下方式计算时延：同B3。
实现方式B8、源网络设备以SDAP SDU形式转移切换的数据单元给目标网络设备。源网络设备转移SDAP SDU，并在GTP-U的扩展头中携带了相当于源网络设备中一个绝对时间的时间偏移，即相对时间信息，且目标网络设备把GTP-U中携带的相对时间信息增加到PDCP PDU中携带。GTP-U中携带的该绝对时间为源网络设备收到数据包的时刻。UE根据如下方式计算时延：同B4。
具体实现中，UE向目标网络设备发送没有被源网络设备正确接收的数据单元，此时，接收端设备是目标网络设备时，由目标网络设备计算时延信息。具体包括如下B9和B10两种实现方式：
实现方式B9、UE向目标网络设备发送未被源网络设备正确接收的数据单元。目标网络设备根据源网络设备和目标网络设备的时间偏差计算时延。例如，目标网络设备发现该数据单元为从源网络设备转移至目标网络设备的数据单元，则目标网络设备知道其中携带的时间信息是以源网络设备为参考的，则目标网络设备可以根据源网络设备和目标网络设备之间的时间偏差来计算出该携带的时间信息对应的目标网络设备的相对时间。以SDAP层增加时间信息为举例：SDAP PDU的时间信息是对应帧号为frame 1，子帧号为subframe 1，对应的时刻为T1，目标网络设备可以根据源网络设备和目标网络设备的时间偏差知道同一时刻在目标网络设备的相对时间为frame 1，子帧号为subframe 2。之后目标网络设备再根据SDAP层把该数据单元提交给上层的时刻与SDAP PDU中携带的时间信息转换为目标网络设备的相对时间之间的差值作为该数据单元的时延。
实现方式B10、UE向目标网络设备发送未被源网络设备正确接收的数据单元。目标网络设备根据源网络设备和目标网络设备的时间偏差计算时延。例如，目标网络设备发现该数据单元为从源网络设备转移至目标网络设备的数据单元，则目标网络设备知道其中携带的时间信息是以源网络设备为参考的，则目标网络设备可以根据源网络设备和目标网络设备之间的时间偏差来计算出该携带的时间信息对应的目标网络设备的相对时间。以SDAP层增加时间信息为举例：目标网络设备发现该数据单元为从源网络设备转移至目标网络设备的数据单元，则可以获知SDAP PDU中携带的时间信息对应绝对时间参考点1，从而再根据SDAP PDU中携带的时间信息知道该时间信息对应的的绝对时间T1。例如，目标网络设备知道源网络设备发送的绝对时间参考点的信息(即目标网络设备知道源网络设备的绝对时间参考点的时域位置)，例如，时域位置是指帧号，子帧号的位置信息。这样目标网络设备根据定时偏差知道该数据单元对应的时间参考点是哪一个，从而知道对应的绝对时间T1，目标网络设备再根据绝对时间T1获得在目标网络设备对应的绝对时间参考点2和相对时间2，之后根据目标网络设备的PDCP层把数据单元提交给上层的绝对时间为T2(在目标网络设备对应的绝对时间参考点2和相对时间3)和绝对时间T1(在目标网络设备对应的绝对时间参考点2和相对时间2)计算时延。
具体实现中，源网络设备需要将从UE接收到的乱序的数据单元转移到目标网络设备，从而目标网络设备计算出这些乱序的数据单元对应的时延。需要说明的是，只有在无损切换下才会进行上行转移。一种方法是采用前面的A17～A23中的方法。另外一种方法是采用如下的B11。
实现方式B11、源网络设备以SDAP PDU或PDCP SDU形式转移切换的数据单元给目标网络设备。源网络设备在SDAP PDU的报文头中携带了时间信息，该时间信息可能是以源网络设备定时为参考的相对时间(帧号、子帧号等)，或者是以源网络设备中一个绝对时间的无线帧为参考的时间偏移。目标网络设备根据源网络设备和目标网络设备的时间偏差计算时延：同B9～B10。
本申请还提出了一种在CU-DU架构下，CU如何获取绝对时间与无线帧号或/和子帧号之间的对应关系，从而CU在SDAP/PDCP层设置时间信息。比如在本申请中，CU在SDAP/PDCP层携带时间信息时，时间信息携带的是以某个绝对时间作为参考的时间偏移。基站会通知UE某个无线帧号或子帧号对应的绝对时间，比如通过广播消息或者无线资源控制(radio resource control，RRC)消息通知UE。
可选地，DU负责配置广播消息中绝对时间与无线帧号或/和子帧号的关系给UE。DU给CU发送消息，消息中携带了绝对时间与帧号或/和子帧号的对应关系，各个系统信息块(system information block，SIB)的调度安排，比如各个SIB的调度列表及系统消息的窗口大小、系统信息的周期等中的至少一项。CU可以知道每一个时刻对应的无线帧号或/和子帧号，从而CU知道如何在SDAP/PDCP层设置数据单元对应的时间信息。
可选地，CU负责配置广播消息中绝对时间与无线帧号或/和子帧号的关系给UE。CU给DU发送消息，消息中携带了绝对时间与帧号/和子帧号的对应关系，各个系统信息块SIB(system information block)的调度安排，比如各个SIB的调度列表及系统消息的窗口大小、系统信息的周期等中的至少一项。从而DU可以知道如何调度各个系统消息。
可选地，CU负责配置广播消息中绝对时间与无线帧号或/和子帧号的关系给UE，DU给CU发送消息，消息中携带了至少携带了绝对时间与帧号或/和子帧号的对应关系，各个系统信息块SIB(system information block)的调度安排，比如各个sib的调度列表及系统消息的窗口大小、系统信息的周期等中的至少一项。
可选的，可以由CU-UP和DU之间交互以上信息，或者由CU-CP和DU之间交互以上信息，再由CU-CP和CU-UP之间交互以上信息。其中，以上信息是指绝对时间与帧号/和子帧号的对应关系，各个系统信息块的调度安排。
图12为本申请实施例提出的又一种通信方法的流程示意图。具体地，在本申请中，网络设备侧和UE的数据单元对应的时间信息是以某个绝对时间点作为参考对应的相对时间。
S1201、网络设备通知UE当前的绝对时间。
在一个实现方式中，网络设备可以在广播消息中广播当前的绝对时间。例如，广播消息中携带了该广播消息对应的广播消息窗口的结束边界上或者之后的系统帧号(system frame number,SFN)边界对应的绝对时间。
在另一个实现方式中，网络设备可以在无线资源控制(radio resource control，RRC)消息(例如，下行信息传输消息(downlink information transfer message))中通知UE当前的绝对时间。例如，通知某个SFN结束边界对应的绝对时间。
以上绝对时间可能携带的是相对于某个固定绝对时间之后的偏移时间。例如，这个固 定时间为阳历1900年1月1号00:00:00(1899年12月31日和1900年1月1日之间的午夜)，或者1980年1月6号00:00:00(全球定位系统(global positioning system，GPS)时间)。绝对时间可能是协调世界时(coordinated universal time，UTC)时间，也可能是GPS时间。具体内容可以参考3GPP 36.331中的sib 16或者下行信息传输消息中携带时间的方法。
S1202、发送端设备发送数据单元和第一时间信息。
在上行传输中，该发送端设备可以是UE，接收端设备可以是网络设备；在下行传输中，该发送端设备可以是网络设备，接收端设备可以是UE。如图12所示的流程是以下行传输为例的。
其中，第一时间信息是对应该数据单元的。发送的第一时间信息可以是相对于某个绝对时间的偏移。例如，网络设备会通知(通过广播消息或者RRC消息)UE时间参考点的配置：以某个绝对时间为起点，每隔一定时间作为一个周期，即通知这个起点和/或这个周期。或者协议规定了这些内容。携带的第一时间信息是相对于当前周期的起始点的时间偏移。例如，以某个绝对时间(例如，阳历1900年1月1号00:00:00，即阳历1899年12月31号和1900年1月1日之前的午夜，或者阳历1980年1月6日00:00:00)为起点，每1s为一个周期。假设发送端设备发送某个数据单元时对应的绝对时间为2018年11月7日10点11分15秒20毫秒，则时间参考点是2018年11月7日10点11分15秒，携带的第一时间信息是20毫秒。需要说明的是，本实施例中还需要额外解决CU-CP和CU-UP场景下的CU-UP如何知道这些时间参考点的配置。例如，CU-CP需要通知CU-UP这些时间参考点的配置，即以某个绝对时间为起点，每隔一定时间作为一个周期，即通知这个起点和/或这个周期。
可选地，携带的第一时间信息可能是当前绝对时间的一部分，例如，只是携带当前绝对时间的毫秒和微秒内容。假设发送端设备发送某个数据单元时对应的绝对时间为2018年11月7日10点11分15秒20毫秒10微秒，则携带的时间信息就是20毫秒10微秒。网络设备会通知(通过广播消息或者RRC消息)UE时间信息是当前绝对时间的哪一部分。需要说明的是，本实施例中还需要额外解决CU-CP和CU-UP场景下的CU-UP如何知道这些配置的问题。例如，CU-CP需要通知CU-UP时间信息携带当前绝对时间的哪些部分，例如，只是携带当前绝对时间的毫秒和微秒内容。
S1203、接收端设备收到数据单元和第一时间信息之后，根据第一时间信息和接收到该数据单元的第二时间信息，计算时延。
接收端收到数据单元和第一时间信息时，计算该数据单元的时延，即为终点时刻减去起始点时刻。起始点时刻是数据单元对应的第一时间信息，终点时刻是接收端设备收到该数据单元的时刻，或者接收端设备把该数据单元提交给其他层的时刻(比如接收端设备的PDCP层提交给SDAP层，或者接收端设备的PDCP层提交给IP层或者核心网)。
当携带的第一时间信息是相对于某个绝对时间的偏移时，如果接收端设备判断出起始点和终止点对应的周期参考点不同，则接收端设备计算时延时需要补偿对应的周期参考点的差别。例如，起始点对应的周期参考点T1在终止点对应的周期参考点T2之前,携带的第一时间信息是相对于周期参考点T1的偏移Offset 1，起始点对应的时刻是T1+Offset1,终点时刻是相对周期参考点T2的偏移是Offset 2,终止点对应的时刻是T2+Offset 2，则接收 端设备需要补偿两个周期参考点之间的差别，即时延为:T2+Offset 2–(T1+Offset 1)。
携带的第一时间信息可能是当前绝对时间的一部分(例如，毫秒和微秒)，接收端设备可以判断出起始点的绝对时间。例如，如果当前终点对应的绝对时间的一部分(例如，毫秒和微秒)比起始点更小，则接收端设备知道携带的第一时间信息是比当前绝对时间中秒单位更早1秒对应的毫秒和微秒。
根据本申请实施例提供的一种通信方法，网络设备明确以绝对时间作为参考，发送端设备将发送数据单元的时间信息通知接收端设备，该时间信息可以是绝对时间或绝对时间的一部分，接收端设备可以根据该数据单元对应的时间信息和接收到该数据单元的时间信息，准确地计算出发送端设备发送数据单元和接收端设备接收数据单元之间的时延。
本申请实施例还提供了一种切换过程中对从源网络设备转移至目标网络设备的数据单元不进行时延测量的方法。
一种方法为：目标网络设备或目标小区给UE发送从源网络设备或源小区转移过来的下行数据单元的时候，目标网络设备或目标小区发送该数据单元的时候，不携带时间信息或指示无需进行时延测量。目标网络设备或目标小区接收到从源网络设备或源小区转移过来的上行数据单元的时候，目标网络设备或目标小区不计算这些上行数据单元的时延。UE在目标网络设备或目标小区传输那些切换之前已经关联了PDCP SN的PDCP SDU时，UE传输这些数据单元的时候，不携带时间信息或指示无需进行时延测量。
另外一种可选方法为：目标网络设备在给UE的切换命令中携带一个定时器，该定时器定义了UE在收到切换命令之后或者PDCP重建之后的该定时器时间内，上行数据单元不携带时间信息或指示数据单元无需时延测量，无需计算下行数据单元的时延。
本申请实施例还提供了一种切换过程中对从源网络设备转移至目标网络设备的数据单元进行时延测量时不考虑切换带来的时延的方法。
一种方法为：目标网络设备或目标小区给UE发送从源网络设备或源小区转移过来的下行数据单元的时候，目标网络设备或目标小区发送该数据单元的时候，携带的时间是目标网络设备或目标小区收到该数据单元的时刻。UE在目标网络设备或目标小区那些切换之前已经关联了PDCP SN的PDCP SDU时，携带的时间是UE准备在目标网络设备或目标小区发送这些该数据单元的时刻。
基于上述实施例中的通信方法的同一构思，如图13所示，本申请实施例还提供一种通信装置1300，该通信装置可应用于上述图2所示的通信方法中。在下行切换场景中，该通信装置1300可以是如图1-1所示的网络设备100，也可以是应用于该网络设备100的一个部件(例如芯片)；在终端设备发送数据单元的场景中，该通信装置1300可以是如图1-1所示的终端设备200，也可以是应用于该终端设备200的一个部件(例如芯片)。该通信装置1300包括：处理单元131和通信单元132；其中：
处理单元131，用于获取数据单元对应的第一时间的信息，所述第一时间以源网络设备的定时作为参考；
所述处理单元131还用于确定所述数据单元对应的第二时间的信息，所述第二时间以所述目标网络设备的定时作为参考；
通信单元132，用于向接收端设备发送所述第二时间的信息。
在一个实现方式中，所述通信单元132还用于接收来自所述接收端设备的时延信息，其中，所述时延信息为所述接收端设备根据所述第二时间的信息与所述接收端设备获取所述数据单元的第三时间的信息计算得到的。
在另一个实现方式中，所述通信单元132还用于从所述源网络设备接收所述数据单元对应的所述第一时间的信息。
在又一个实现方式中，所述处理单元131还用于从包数据汇聚协议PDCP层获取所述数据单元对应的第一时间的信息。
有关上述处理单元131和通信单元132更详细的描述可以直接参考上述图2所示的方法实施例中网络设备的相关描述直接得到，这里不加赘述。
基于上述实施例中的通信方法的同一构思，如图14所示，本申请实施例还提供一种通信装置1400，该通信装置可应用于上述图9所示的通信方法中。在下行切换场景中，该通信装置1400可以是如图1-1所示的网络设备100，也可以是应用于该网络设备100的一个部件(例如芯片)；在终端设备发送数据单元的场景中，该通信装置1400可以是如图1-1所示的终端设备200，也可以是应用于该终端设备200的一个部件(例如芯片)。该通信装置1400包括：处理单元141，可选地，还包括通信单元142；其中：
处理单元141，用于获取数据单元对应的第一时间的信息，所述第一时间以源网络设备的定时作为参考；
所述处理单元141还用于确定所述数据单元对应的第二时间的信息，所述第二时间以所述目标网络设备的定时作为参考；
所述处理单元141还用于根据所述第二时间的信息和发送所述数据单元的时刻，确定所述数据单元的时延信息。
在一个实现方式中，通信单元142，用于从所述源网络设备接收所述数据单元对应的第一时间的信息。
在另一个实现方式中，所述处理单元141还用于从包数据汇聚协议PDCP层获取所述数据单元对应的第一时间的信息。
在又一个实现方式中，所述通信单元142还用于向网管系统发送所述时延信息。
有关上述处理单元141和通信单元142更详细的描述可以直接参考上述图9所示的方法实施例中网络设备的相关描述直接得到，这里不加赘述。
基于上述实施例中的通信方法的同一构思，如图15所示，本申请实施例还提供一种通信装置1500，该通信装置可应用于上述图10所示的通信方法中。在下行切换场景中，该通信装置1500可以是如图1-1所示的网络设备100，也可以是应用于该网络设备100的一个部件(例如芯片)；在终端设备发送数据单元的场景中，该通信装置1500可以是如图1-1所示的终端设备200，也可以是应用于该终端设备200的一个部件(例如芯片)。该通信装置1500包括：处理单元151，可选地，还包括通信单元152；其中：
处理单元151，用于获取数据单元对应的第一时间的信息，所述第一时间以源网络设 备的定时作为参考；
所述处理单元151还用于根据所述第一时间的信息、定时偏差、以及所述接收端设备获取所述数据单元的第二时间的信息，确定所述接收端设备获取所述数据单元的时延信息。
在一个实现方式中，通信单元152，用于从发送端设备接收所述数据单元对应的第一时间的信息。
在另一个实现方式中，所述通信单元152还用于接收来自所述发送端设备的第一指示，所述第一指示用于指示所述数据单元为从所述源网络设备转移至所述目标网络设备的数据单元。
在又一个实现方式中，所述通信单元152还用于向所述发送端设备发送所述时延信息。
在又一个实现方式中，所述通信单元152还用于向网管系统发送所述时延信息。
有关上述处理单元151和通信单元152更详细的描述可以直接参考上述图10所示的方法实施例中网络设备的相关描述直接得到，这里不加赘述。
本申请实施例中还提供一种通信装置，该通信装置用于执行上述通信方法。上述通信方法中的部分或全部可以通过硬件来实现也可以通过软件来实现。
可选的，通信装置在具体实现时可以是芯片或者集成电路。
可选的，当上述实施例的通信方法中的部分或全部通过软件来实现时，通信装置包括：存储器，用于存储程序；处理器，用于执行存储器存储的程序，当程序被执行时，使得通信装置可以实现上述实施例提供的通信方法。
可选的，上述存储器可以是物理上独立的单元，也可以与处理器集成在一起。
可选的，当上述实施例的通信方法中的部分或全部通过软件实现时，通信装置也可以只包括处理器。用于存储程序的存储器位于通信装置之外，处理器通过电路/电线与存储器连接，用于读取并执行存储器中存储的程序。
处理器可以是中央处理器(central processing unit，CPU)，网络处理器(network processor，NP)或者CPU和NP的组合。
处理器还可以进一步包括硬件芯片。上述硬件芯片可以是专用集成电路(application-specific integrated circuit，ASIC)，可编程逻辑器件(programmable logic device，PLD)或其组合。上述PLD可以是复杂可编程逻辑器件(complex programmable logic device，CPLD)，现场可编程逻辑门阵列(field-programmable gate array，FPGA)，通用阵列逻辑(generic array logic,GAL)或其任意组合。
存储器可以包括易失性存储器(volatile memory)，例如随机存取存储器(random-access memory，RAM)；存储器也可以包括非易失性存储器(non-volatile memory)，例如快闪存储器(flash memory)，硬盘(hard disk drive，HDD)或固态硬盘(solid-state drive，SSD)；存储器还可以包括上述种类的存储器的组合。
所属领域的技术人员可以清楚地了解到，为描述的方便和简洁，上述描述的系统、装置和单元的具体工作过程，可以参考前述方法实施例中的对应过程，在此不再赘述。
在本申请所提供的几个实施例中，应该理解到，所揭露的系统、装置和方法，可以通过其它的方式实现。例如，该单元的划分，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，例如，多个单元或组件可以结合或者可以集成到另一个系统，或一些特 征可以忽略，或不执行。所显示或讨论的相互之间的耦合、或直接耦合、或通信连接可以是通过一些接口，装置或单元的间接耦合或通信连接，可以是电性，机械或其它的形式。
作为分离部件说明的单元可以是或者也可以不是物理上分开的，作为单元显示的部件可以是或者也可以不是物理单元，即可以位于一个地方，或者也可以分布到多个网络单元上。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案的目的。
在上述实施例中，可以全部或部分地通过软件、硬件、固件或者其任意组合来实现。当使用软件实现时，可以全部或部分地以计算机程序产品的形式实现。该计算机程序产品包括一个或多个计算机指令。在计算机上加载和执行该计算机程序指令时，全部或部分地产生按照本申请实施例的流程或功能。该计算机可以是通用计算机、专用计算机、计算机网络、或者其他可编程装置。该计算机指令可以存储在计算机可读存储介质中，或者通过该计算机可读存储介质进行传输。该计算机指令可以从一个网站站点、计算机、服务器或数据中心通过有线(例如同轴电缆、光纤、数字用户线(digital subscriber line，DSL))或无线(例如红外、无线、微波等)方式向另一个网站站点、计算机、服务器或数据中心进行传输。该计算机可读存储介质可以是计算机能够存取的任何可用介质或者是包含一个或多个可用介质集成的服务器、数据中心等数据存储设备。该可用介质可以是只读存储器(read-only memory，ROM)，或随机存储存储器(random access memory，RAM)，或磁性介质，例如，软盘、硬盘、磁带、磁碟、或光介质，例如，数字通用光盘(digital versatile disc，DVD)、或者半导体介质，例如，固态硬盘(solid state disk，SSD)等。

Claims (25)

  1. 一种通信方法，其特征在于，包括：
    发送端设备获取数据单元对应的第一时间的信息，所述第一时间以源网络设备的定时作为参考；
    所述发送端设备确定所述数据单元对应的第二时间的信息，所述第二时间以所述目标网络设备的定时作为参考；
    所述发送端设备向接收端设备发送所述第二时间的信息。
  2. 如权利要求1所述的方法，其特征在于，所述第二时间是根据所述第一时间和定时偏差确定的，所述定时偏差包括所述目标网络设备与所述源网络设备的定时偏差。
  3. 如权利要求1或2所述的方法，其特征在于，所述发送端设备为目标网络设备，所述接收端设备为终端设备，所述方法还包括：
    所述发送端设备接收来自所述接收端设备的时延信息，其中，所述时延信息为所述接收端设备根据所述第二时间的信息与所述接收端设备获取所述数据单元的第三时间的信息计算得到的。
  4. 如权利要求3所述的方法，其特征在于，所述发送端设备获取数据单元对应的第一时间的信息，包括：
    所述发送端设备从所述源网络设备接收所述数据单元对应的所述第一时间的信息。
  5. 如权利要求4所述的方法，其特征在于，所述第一时间的信息携带在服务数据适配协议SDAP协议数据单元PDU的报头中，或携带在通用分组无线服务用户面隧道协议GTP-U报文对应的扩展报头中。
  6. 如权利要求3所述的方法，其特征在于，所述发送端设备获取数据单元对应的第一时间的信息，包括：
    所述发送端设备从包数据汇聚协议PDCP层获取所述数据单元对应的第一时间的信息。
  7. 如权利要求1～6中任一项所述的方法，其特征在于，所述第一时间的信息包括以下一种或两种时间信息：相对时间信息、绝对时间信息。
  8. 一种通信方法，其特征在于，包括：
    目标网络设备获取数据单元对应的第一时间的信息，所述第一时间以源网络设备的定时作为参考；
    所述目标网络设备确定所述数据单元对应的第二时间的信息，所述第二时间以所述目标网络设备的定时作为参考；
    所述目标网络设备根据所述第二时间的信息和发送所述数据单元的时刻，确定所述数据单元的时延信息。
  9. 如权利要求8所述的方法，其特征在于，所述第二时间是根据所述第一时间和定时偏差确定的，所述定时偏差包括所述目标网络设备与所述源网络设备的定时偏差。
  10. 如权利要求8或9所述的方法，其特征在于，所述目标网络设备获取数据单元对应的第一时间的信息，包括：所述目标网络设从所述源网络设备接收所述数据单元对应的第一时间的信息。
  11. 如权利要求10所述的方法，其特征在于，所述第一时间的信息携带在服务数据适配协议SDAP协议数据单元PDU的报头中，或携带在通用分组无线服务用户面隧道协议GTP-U报文对应的扩展报头中。
  12. 如权利要求8或9所述的方法，其特征在于，所述目标网络设备获取数据单元对应的第一时间的信息，包括：所述目标网络设备从包数据汇聚协议PDCP层获取所述数据单元对应的第一时间的信息。
  13. 如权利要求8～12任一项所述的方法，其特征在于，所述第一时间的信息包括以下一种或两种时间信息：相对时间信息、绝对时间信息。
  14. 如权利要求8所述的方法，其特征在于，还包括：
    所述目标网络设备向网管系统发送所述时延信息。
  15. 一种通信方法，其特征在于，包括：
    接收端设备获取数据单元对应的第一时间的信息，所述第一时间以源网络设备的定时作为参考；
    所述接收端设备根据所述第一时间的信息、定时偏差、以及所述接收端设备获取所述数据单元的第二时间的信息，确定所述接收端设备获取所述数据单元的时延信息。
  16. 如权利要求15所述的方法，其特征在于，所述第二时间以目标网络设备的定时作为参考。
  17. 如权利要求15或16所述的方法，其特征在于，所述接收端设备获取数据单元对应的第一时间的信息，包括：
    所述接收端设备从发送端设备接收所述数据单元对应的第一时间的信息。
  18. 如权利要求15～17任一项所述的方法，其特征在于，所述接收端设备为终端设备，所述发送端设备为目标网络设备，所述方法还包括：
    所述接收端设备接收来自所述发送端设备的第一指示，所述第一指示用于指示所述数据单元为从所述源网络设备转移至所述目标网络设备的数据单元。
  19. 如权利要求18所述的方法，其特征在于，所述方法还包括：
    所述接收端设备向所述发送端设备发送所述时延信息。
  20. 如权利要求17所述的方法，其特征在于，所述第一时间的信息携带在服务数据适配协议SDAP协议数据单元PDU的报头中，或携带在PDCP PDU的报头中。
  21. 如权利要求15～20中任一项所述的方法，其特征在于，所述第一时间信息包括以下一种或两种时间信息：相对时间信息、绝对时间信息。
  22. 如权利要求15～17任一项所述的方法，其特征在于，所述发送端设备为终端设备，所述接收端设备为目标网络设备，所述方法还包括：
    所述接收端设备向网管系统发送所述时延信息。
  23. 一种通信装置，包括处理器，所述处理器与存储器耦合，所述存储器用于存储计算机程序或指令，所述处理器用于执行存储器中的该计算机程序或指令，使得所述通信装置执行如权利要求1～7任一项所述的方法或者如权利要求8～14任一项所述的方法或者如权利要求15～22任一项所述的方法。
  24. 一种计算机程序产品，用于当在计算设备上执行时，实现如权利要求1～7任一项所述的方法或者如权利要求8～14任一项所述的方法或者如权利要求15～22任一项所述的方法。
  25. 一种计算机可读存储介质，其上存储有计算机程序，其特征在于，该程序被处理器执行时实现如权利要求1～7任一项所述的方法或者如权利要求8～14任一项所述的方法或者如权利要求15～22任一项所述的方法。
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