WO2020043083A1 - 一种数据传输方法和装置 - Google Patents

一种数据传输方法和装置 Download PDF

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Publication number
WO2020043083A1
WO2020043083A1 PCT/CN2019/102761 CN2019102761W WO2020043083A1 WO 2020043083 A1 WO2020043083 A1 WO 2020043083A1 CN 2019102761 W CN2019102761 W CN 2019102761W WO 2020043083 A1 WO2020043083 A1 WO 2020043083A1
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WO
WIPO (PCT)
Prior art keywords
data
base station
terminal
radio bearer
target base
Prior art date
Application number
PCT/CN2019/102761
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English (en)
French (fr)
Inventor
胡星星
曾清海
王瑞
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 EP19855665.6A priority Critical patent/EP3836598B1/en
Publication of WO2020043083A1 publication Critical patent/WO2020043083A1/zh
Priority to US17/186,030 priority patent/US11711731B2/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/12—Reselecting a serving backbone network switching or routing node
    • H04W36/125—Reselecting a serving backbone network switching or routing node involving different types of service backbones
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/04—Arrangements for maintaining 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
    • H04W36/0022—Control or signalling for completing the hand-off for data sessions of end-to-end connection for transferring data sessions between adjacent core network technologies
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0058—Allocation criteria
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/02—Buffering or recovering information during reselection ; Modification of the traffic flow during hand-off
    • H04W36/023—Buffering or recovering information during reselection
    • H04W36/0235—Buffering or recovering information during reselection by transmitting sequence numbers, e.g. SN status transfer
    • 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
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/14—Reselecting a network or an air interface
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/14—Reselecting a network or an air interface
    • H04W36/144—Reselecting a network or an air interface over a different radio air interface technology
    • 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
    • H04W36/0055—Transmission or use of information for re-establishing the radio link
    • H04W36/0066—Transmission or use of information for re-establishing the radio link of control information between different types of networks in order to establish a new radio link in the target network
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W92/00—Interfaces specially adapted for wireless communication networks
    • H04W92/16—Interfaces between hierarchically similar devices
    • H04W92/20—Interfaces between hierarchically similar devices between access points

Definitions

  • the present application relates to the field of communication technologies, and in particular, to a data transmission method and device.
  • the wireless communication system consists of network-side equipment and terminals.
  • the network equipment consists of a base station and a core network, and the terminal completes the task of wireless communication by interacting with the network side.
  • the wireless communication technology between the base station and the terminal is called Long Term Evolution (LTE), the corresponding base station is called LTE evolved NodeB (eNB), and the core network is called evolved packet.
  • Core network evolved packet core, EPC.
  • the wireless communication technology between the base station and the terminal is called a new air interface (new radio, NR)
  • the corresponding base station is called a gNB
  • the core network is called a 5GC (5generation core).
  • the wireless communication standard allows eNBs to connect to the 4G core network EPC (that is, the terminal connects to the EPC through the LTE eNB), and also allows eNBs to connect to the 5G core network 5GC.
  • the base station may be referred to as an evolved long-term evolution (eLTE) eNB, and is also referred to as an ng-eNB.
  • eLTE eNB is allowed to connect to EPC and 5GC at the same time, or one cell can be connected to EPC and 5GC at the same time.
  • the communication data between the base station and the terminal can be processed by using various layers of LTE wireless protocols, such as LTE Packet Data Convergence Protocol (PDCP) / LTE Radio Link Control (Radio Link Control (RLC) / LTE Medium Access Control (MAC) / LTE physical layer (Physical, PHY); when the terminal is connected to the 5GC through the base station gNB, the communication data between the base station and the terminal can use the wireless protocols of each layer of NR Standards, such as NR Service Data Adaptation Protocol (SDAP) / NR PDCP / NR RLC / NR MAC / NR PHY.
  • SDAP NR Service Data Adaptation Protocol
  • the communication data of the base station and the terminal can comprehensively adopt the wireless protocol standards of each layer of NR / LTE, such as NR SDAP / NR PDCP / LTE RLC / LTE MAC / LTE PHY.
  • some services require the data packets to be submitted in order (that is, the data packets must be sent to the peer in a sequential relationship.
  • the base station receives data from the terminal, the base station must receive data in a certain order The relationship is submitted to the core network).
  • the sender In the communication between the base station and the terminal, the sender generally assigns a sequence number to certain wireless protocols for the data packet, so that the receiver can judge the data according to the sequence relationship of the sequence number. Are the packages out of order?
  • Operators may deploy LTE base stations in some areas and eLTE base stations in other areas.
  • a terminal moves from an LTE eNB to an eLTE eNB, a corresponding core network handover is required.
  • the base station is connected to the EPC and 5GC at the same time.
  • some terminals need to be switched between EPC and 5GC.
  • the terminal needs a corresponding handover when moving from the LTE eNB to the gNB.
  • the radio bearer between the base station and the terminal adopts different protocols, which may cause data loss and out-of-order submission.
  • the terminal connected to the EPC through the LTE base station is switched to the NR base station connected to the 5GC, for the downlink data:
  • the source cell will transfer it to the source core network, and the source core network
  • the downlink data is then transmitted to the terminal through the target core network and the target cell, and the target cell reassigns a serial number to the downlink data.
  • the wireless protocol layer of the terminal submits the data received from the source cell to the upper layer during the handover process, and then receives the data in the target cell.
  • the order of the data packets from the source core network is data packets 1, 2, 3, 4, 5, and data packets 1, 3 5 and 5 are correctly received by the terminal, and data packets 2 and 4 are not correctly received by the terminal.
  • the wireless protocol layer of the terminal will submit data packets 1, 3, and 5 to the upper layer during the handover process, and then receive the data from the target cell. Packets 2 and 4 are submitted to the upper layer, which causes the upper layer to receive data packets 1, 2, 3, 4, and 5 out of order.
  • This application provides a data transmission method and device to ensure that data is not lost during the communication between the terminal and the base station and can be submitted in order.
  • this application provides a data transmission method.
  • the method includes: a source base station determining a first data and a wireless air interface protocol sequence number of a data unit used to carry the first data, such as an SN number, where
  • the first data includes: data that the source base station and the terminal did not confirm to receive correctly during the data transmission process; the source base station sends the first data and the wireless air interface protocol sequence number to the target base station;
  • the core network connected to the target base station is different from the core network connected to the source base station, and the source base station and the target base station are the source base station and the target base station during the handover process of the different core networks of the terminal.
  • the source base station sends data to the target base station that has not been correctly received by the terminal during data transmission between the source base station and the terminal, and the data unit corresponding to these data carries the wireless air interface serial number, so that the target base station receives the data.
  • the data packets with the original wireless air interface serial number are sent, these serial numbers and data packets are sent to the terminal. Because these wireless air interface serial numbers are in the same order as the data packets that the terminal received correctly before, the terminal can The data packets are correctly ordered, thereby ensuring that all received data packets are submitted to the upper layer in order.
  • the method further includes: the source base station determines second data, where the second data includes: a process of switching the terminal in the core network And the source base station receives data to be sent to the terminal from the source core network; the source base station sends the second data to the target base station, so that the target base station responds to the second data in accordance with the second data.
  • the serial number of the wireless air interface protocol corresponding to the first data, and the serial number of the wireless air interface protocol of the data unit of the second data is continuously allocated.
  • the source base station sends the generated second data and the wireless air interface protocol sequence number corresponding to the second data to the target base station. Because the wireless air interface protocol sequence number corresponding to the second data is Based on the first data, the configuration is continued, so the target base station and terminal at the receiving end can identify and correctly sort, thereby ensuring that the received data packets are submitted in order.
  • the method before the source base station sends the first data and the wireless air interface protocol sequence number to the target base station, the method It also includes: the source base station configures the terminal with first radio bearer information, the first radio bearer information is used to establish a radio bearer between the source base station and the terminal; the source base station sends to the target base station The first radio bearer information; the source base station receiving a confirmation message fed back by the target base station, the confirmation message being used to indicate second radio bearer information between the target base station and the terminal; the source base station Sending the second radio bearer information to the terminal.
  • the first radio bearer information includes a radio bearer configuration. Further, the radio bearer configuration includes a DRB identifier, NR PDCP configuration information corresponding to the DRB, and NR SDAP configuration information. Further, the NR SDAP configuration information includes a mapping relationship between a DRB and a QoS flow configured by the source base station for the UE. In addition, the NR SDAP configuration information further includes at least one of the following: a PDU session carried by the DRB ID, whether the SDAP upstream and downstream SDAP packet headers are configured, and whether the DRB is the default DRB. In addition, the radio bearer configuration may further include a DRB configuration configured by the source base station for the UE. The DRB configuration specifically includes a DRB identifier, PDCP information configured by the source base station corresponding to the DRB for the UE, and the like.
  • the confirmation message is further used to indicate third radio bearer information
  • the third radio bearer information is used to configure a third radio bearer information.
  • Data configuration information, and the third data is data received from a target core network of the target base station.
  • the third radio bearer information is fed back, so that the target base station can determine, according to the third radio bearer information, to bear data delivered by the target core network, and perform the newly issued data according to the protocol rules of the target core network.
  • the sequence numbers are sequenced to avoid confusion with the first data and the second data, and further ensure that the target base station receives and processes the different data from the source base station and the target core network in an orderly manner.
  • the source base station sends the first data and the wireless air interface protocol sequence number to the target base station, including: the source base station passes the The first tunnel sends to the target base station the data in the first data that has not been confirmed to be correctly received by the terminal and the wireless air interface protocol sequence number.
  • the first data further includes: an out-of-order data packet received by the source base station from the terminal, and the source base station sends
  • the sending of the first data and the wireless air interface protocol sequence number by the target base station includes: the source base station sends the out-of-order data packets from the terminal in the first data to the target base station through the second tunnel, and The wireless air interface protocol sequence number corresponding to the out of order data packet.
  • the terminal sends uplink out-of-sequence data packets and corresponding sequence numbers to the target cell or target base station, thereby avoiding the loss of some data packets that are sent but not received by the source base station or source cell.
  • the present application also provides a data transmission method.
  • the method includes: the target base station receives first data from the source base station and a wireless air interface protocol sequence number, and the first data includes: the source base station and the terminal.
  • Data that is not correctly received by the terminal during data transmission, the wireless air interface protocol sequence number is the serial number of the data unit determined by the source base station to carry the first data; the target base station sends the terminal to the terminal The first data and the wireless air interface protocol sequence number; wherein the core network connected to the target base station is different from the core network connected to the source base station, and the source base station and the target base station are the terminal Source base station and target base station in different core network handover processes.
  • the method further includes: the target base station receives second data from the source base station, and the second data includes the terminal During the core network handover process, the source base station receives data to be sent to the terminal from the source core network; the target base station continues to allocate the second data according to the wireless air interface protocol sequence number corresponding to the first data The wireless air interface protocol sequence number of the data unit of the second data; the target base station sending the second data and the wireless air interface protocol sequence number of the data unit of the second data to the terminal.
  • the method before the target base station receives the first data from the source base station and the wireless air interface protocol sequence number, the method further includes: the target The base station receives first radio bearer information from a source base station, where the first radio bearer information is used to establish a radio bearer between the target base station and the terminal; the target base station determines a second radio bearer according to the first radio bearer information. Bearer information, and generating a confirmation message, the confirmation message is used to indicate the second radio bearer information between the target base station and the terminal; the target base station sends the confirmation message to the source base station.
  • the method further includes: the target base station determines third radio bearer information according to the first radio bearer information, and the third The radio bearer information includes configuration information of a target core network to which the target base station is connected; the target base station sends the third radio bearer information to the source base station through the confirmation message.
  • the second radio bearer information includes a first radio bearer; the target base station sends the first data to the terminal and
  • the wireless air interface protocol sequence number includes a wireless air interface protocol sequence number of a data unit in which the target base station sends the second data and the second data to the terminal through the first radio bearer.
  • the second radio bearer information includes a first radio bearer; the target base station sends the second radio bearer to the terminal
  • the wireless air interface protocol sequence number of the data unit of the data and the second data includes: a wireless air interface of the data unit of the target base station sending the second data and the second data to the terminal through the first radio bearer Protocol serial number.
  • the method further includes: the target base station configures a second radio bearer according to the third radio bearer information; the target base station will Third data is sent to the terminal through the second radio bearer, and the third data is data received by a target core network located at the target base station.
  • the method further includes: the target base station sends a handover completion message to the source base station, and the handover completion message includes an end identifier The end identifier is used to instruct the source core network to stop sending data to the source base station.
  • the present application also provides a data transmission method applied to a terminal.
  • the method includes: the terminal receives first data from a target base station and a wireless air interface protocol sequence number, and the first data includes: the source base station and The data received by the terminal during the data transmission process is not confirmed by the terminal, and the serial number of the wireless air interface protocol is the serial number of the data unit determined by the source base station to carry the first data.
  • the wireless air interface protocol sequence number sorts the first data and data buffered in the terminal.
  • the core network to which the target base station is connected is different from the core network to which the source base station is connected.
  • the source base station and the target base station are the source base station and the target base station during the handover process of the different core networks of the terminal.
  • the terminal after the terminal receives the first data from the target core network, because the first data includes the serial number of the data unit of the first data, such as the SN number, the terminal can A piece of data is sorted with the previously successfully received data, thereby ensuring that all data packets are sorted in a certain order, and finally transmitting the sorted data packet to the upper layer.
  • the method further includes: the terminal receiving the second data and the data unit of the second data from the target base station by a wireless air interface protocol
  • the serial number and the second data include: the data that the source base station receives from the source core network to be sent to the terminal during the core network handover process; the terminal according to the data of the second data
  • the wireless air interface protocol sequence number of the unit sorts the second data.
  • the method further includes: the terminal receiving third data from the target base station and data of the third data A wireless air interface protocol sequence number of the unit, and the third data is data received from a target core network of the target base station; and the terminal sends the third data according to the wireless air interface protocol sequence number of the data unit of the third data Sort.
  • the method before the terminal receives the first data from the target base station and the wireless air interface protocol sequence number, the method further includes: Receiving, by the terminal, a handover notification message from the source base station, the handover notification message including a target cell ID accessed to the target base station; the terminal accessing the target cell according to the target cell ID, and Sending a handover completion message to the target base station.
  • the handover notification message may be an RRC reconfiguration message.
  • the handover notification message further includes second radio bearer information, wherein the second radio bearer information includes the first radio bearer information.
  • a radio bearer; a first radio bearer DRB is used to transmit first data with an SN number that is not confirmed by the UE, and the terminal receives the first data from the target base station and a wireless air interface protocol sequence number, including: the terminal uses the first A wireless bearer receives the first data and the wireless air interface protocol sequence number of a data unit of the first data.
  • the handover notification message further includes third radio bearer information, wherein the third radio bearer information includes a second radio bearer information Radio bearer; the second radio bearer DRB is used to transmit a data packet handed over to the target core network, that is, third data, and the terminal receives the third data from the target base station, including: the terminal receives by using the second radio bearer The wireless air interface protocol sequence number of the third data and the data unit of the third data.
  • the third radio bearer information includes a second radio bearer information Radio bearer
  • Radio bearer Radio bearer
  • the second radio bearer DRB is used to transmit a data packet handed over to the target core network, that is, third data
  • the terminal receives the third data from the target base station, including: the terminal receives by using the second radio bearer The wireless air interface protocol sequence number of the third data and the data unit of the third data.
  • the present application further provides a data transmission device.
  • the device may be a source base station, where the device includes a method step for performing the foregoing first aspect and method steps in various implementation manners of the first aspect. unit.
  • the device includes a receiving unit, a processing unit, and a sending unit, and may further include other units or modules such as a storage unit.
  • the present application further provides a data transmission device, where the device may be a target base station, where the device includes a method step for executing the second aspect and the method steps in the various implementation manners of the second aspect. unit.
  • the device includes a receiving unit, a processing unit, and a sending unit, and may further include other units or modules such as a storage unit.
  • the present application further provides a data transmission device, where the device may be a terminal, where the device includes a unit for performing the foregoing third aspect and method steps in various implementation manners of the third aspect. .
  • the device includes a receiving unit, a processing unit, and a sending unit, and may further include other units or modules such as a storage unit.
  • the present application also provides a network device.
  • the network device includes a processor, a transceiver, and a memory.
  • the network device may be a data transmission device, such as a source base station, Target base station, source core network, target core network or terminal.
  • the processor is configured to determine first data and a wireless air interface protocol sequence number of a data unit used to carry the first data, and the first The data includes: data that the source base station and the terminal did not confirm to receive correctly during the data transmission process; the transceiver is configured to send the first data and the wireless air interface protocol sequence number to the target base station; wherein, The core network connected to the target base station is different from the core network connected to the source base station, and the source base station and the target base station are the source base station and the target base station during the handover process of the different core networks of the terminal.
  • processors and the transceiver are also used to implement functions of other various implementations in the foregoing first aspect.
  • the transceiver is configured to receive first data from a source base station and a wireless air interface protocol sequence number, where the first data includes: the source base station and Data that the terminal has not correctly received during the data transmission process, the wireless air interface protocol sequence number is the serial number of the data unit determined by the source base station to carry the first data; and Sending the first data and the wireless air interface protocol sequence number; wherein the core network connected to the target base station is different from the core network connected to the source base station, and the source base station and the target base station are the The source base station and the target base station of the terminal during the handover process of different core networks.
  • processors and the transceiver are also used to implement functions of other various implementations in the foregoing second aspect.
  • the transceiver is configured to receive first data from a target base station and a wireless air interface protocol sequence number, where the first data includes: data between the source base station and the terminal For data that is not correctly received by the terminal during transmission, the wireless air interface protocol sequence number is a serial number of a data unit determined by the source base station to carry the first data; the processor is configured to: Sort the first data and the data buffered in the terminal according to the wireless air interface protocol sequence number; wherein the core network connected to the target base station is different from the core network connected to the source base station, and the source base station And the target base station is a source base station and a target base station of the terminal in a different core network handover process.
  • processors and the transceiver are also used to implement functions of other various implementations in the foregoing third aspect.
  • the present application also provides a computer storage medium, which may store a program, and when the program is executed, the foregoing aspects may be implemented, including some or all of the embodiments of the data transmission method provided by the present application. All steps.
  • the present application further provides a computer program product, where the computer program product includes one or more computer instructions, such as a device upgrade instruction.
  • the computer loads and executes the computer program, some or all steps in the embodiments of the data transmission method provided in the present application may be implemented.
  • the present application also provides a data transmission system.
  • the system includes: a source base station, a source core network, a target base station, a target core network, and a terminal.
  • the source base station may be the fourth aspect described above.
  • the data transmission apparatus in various implementation manners of the fourth aspect
  • the target base station may be the data transmission apparatus in the fifth aspect and the various implementation manners in the fifth aspect
  • the terminal may be the sixth aspect and the sixth aspect
  • the source core network may be an EPC
  • the target core network may be 5GC
  • the source core network may be 5GC
  • the target core network may be an EPC.
  • the present application also provides another data transmission system.
  • the system includes: a base station, a source core network, a target core network, and a terminal.
  • the base station is simultaneously connected to the source core network and the target core network.
  • the connection is located in an area covered by the source core network and the target core network, and the base station has the functions of the source base station and the target base station in the foregoing aspect.
  • the base station has two sets of transmission ports for data transmission with the source core network and the target core network, respectively.
  • the method includes: in the process of data transmission between the base station and the terminal UE, the base station first transmits the core network to the UE through the radio bearer in the fourth radio bearer information before the UE confirms that the handover of the core network is correct
  • the received downlink PDCP SDU such as the fourth data, and the serial number corresponding to the fourth data
  • the base station transmits new data, such as the fifth data, from the target core network to the UE through the radio bearer in the fifth radio bearer information.
  • a serial number corresponding to the fifth data is a serial number corresponding to the fifth data.
  • the method includes: the UE resends the PDCP SDUs that are not correctly received by the base station to the base station through the radio bearer in the fourth radio bearer information; and the radio bearer in the fifth radio bearer information Send the new data packet from the upper layer to the base station.
  • the method includes: the UE first transmits the PDCP SDU that was not successfully transmitted in the radio bearer in the fourth radio bearer information, and After the PDCP and SDU are correctly received by the base station, a new data packet is transmitted on the radio bearer in the fifth radio bearer information.
  • the method includes: the UE does not successfully transmit a PDCP SDU in a radio bearer in the fourth radio bearer information, and Five new data packets are transmitted on the radio bearer in the five radio bearer information.
  • the base station establishes a communication connection with the source core network through the first data transmission channel; and establishes a communication connection with the target core network through the second data transmission channel.
  • the method includes: the base station first receives data in a radio bearer in the fourth radio bearer information, and then sends the data The data of the radio bearer in the fourth radio bearer information is sent to the source core network, and then the data of the radio bearer in the fifth radio bearer information is sent to the target core network. After the data transmission is completed, the base station sends the data to the target core. The network sends a handover complete message.
  • the base station establishes a communication connection with the source core network through a third data transmission channel; or, after the core network is switched, the base station establishes a communication connection with the target core network through a fourth data transmission channel, and the base station and the source The third data transmission channel port between the core networks.
  • the target base station configures the second radio bearer information for the UE by using the first radio bearer information of the source base station, and the DRB in the second radio bearer information is used for the first data transferred from the source base station and / Or second data, and these data retain the wireless air interface sequence number assigned by the source base station, so the receiving target base station can send these data packets to the UE through the DRB, thereby ensuring that the data packets are not lost, and the UE can follow the sequence of the sequence number Sort all the data packets obtained before and after switching the core network, thereby ensuring that all data packets can be submitted to the upper layer in order.
  • the target base station also establishes third radio bearer information, and the radio bearer in the third radio bearer information is used to carry data for handover to the target core network, so that the data of the target core network can be transmitted on the target base station with a new radio bearer. Transmission to avoid out of order with the data packets in the source core network, and further ensure the orderliness of the data packets sent to the UE.
  • FIG. 1a is a schematic diagram of a scenario in which a UE switches between different core networks according to an embodiment of the present application
  • FIG. 1b is a schematic diagram of another scenario in which a UE switches between different core networks according to an embodiment of the present application;
  • FIG. 1b is a schematic diagram of another scenario in which a UE switches between different core networks according to an embodiment of the present application;
  • FIG. 2a is a schematic diagram of a user plane protocol stack when an LTE eNB is connected to an EPC according to an embodiment of the present application;
  • 2b is a schematic diagram of a control plane protocol stack when an LTE eNB is connected to an EPC according to an embodiment of the present application;
  • 2c is a schematic diagram of a user plane protocol stack when an eLTE eNB is connected to a 5GC according to an embodiment of the present application;
  • FIG. 3 is a flowchart of a data transmission method according to an embodiment of the present application.
  • FIG. 5 is a signaling flowchart of a data transmission method according to an embodiment of the present application.
  • 6a is a schematic diagram when a UE-side protocol stack is switched from EPC to 5GC according to an embodiment of the present application;
  • 6b is a schematic diagram when a UE-side protocol stack is switched from 5GC to EPC according to an embodiment of the present application;
  • FIG. 7 is a schematic diagram of data transmission according to an embodiment of the present application.
  • FIG. 9 is a schematic diagram of a scenario in which two core networks are connected to one base station simultaneously according to an embodiment of the present application.
  • FIG. 10 is a signaling flowchart of yet another data transmission method according to an embodiment of the present application.
  • FIG. 11 is a schematic structural diagram of a source base station according to an embodiment of the present application.
  • FIG. 12 is a schematic structural diagram of a target base station according to an embodiment of the present application.
  • FIG. 13 is a schematic structural diagram of a terminal according to an embodiment of the present application.
  • FIG. 14 is a schematic structural diagram of a network device according to an embodiment of the present application.
  • the technical solution of the present application can be applied to a technical scenario in which a terminal switches between different core networks.
  • the different core networks in this scenario include: a 4G core network EPC and a 5G core network 5GC.
  • the EPC is used to provide terminals, such as User Equipment (UE), with the functions of the 4G core network.
  • 5GC is used to provide 5G core network functions for terminals.
  • UE User Equipment
  • LTE eNB LTE base station
  • eLTE eNB LTE base station
  • LTE eNB LTE base station
  • LTE eNB LTE base station
  • gNB NR base station
  • a scenario in which the UE switches between different base stations connected to two core networks It is mainly used for the UE to move from the coverage area of one base station to the coverage area of another base station (for example, it is found that the signal quality of another base station is better). For example, the UE moves from the coverage area of base station 1 to the coverage area of base station 2. In this way, because the radio quality of base station 2 is better, the network side decides to switch the UE to base station 2. However, because base station 2 is only connected to 5GC, the UE needs to switch Core Network.
  • the radio bearer (RB) of the LTE eNB and the terminal adopts the LTE PDCP / LTE RLC / LTE MAC / LTE protocol.
  • the radio bearer of the eLTE eNB and the terminal adopts the NR SDAP / NR PDCP / LTE RLC / LTE MAC / LTE PHY protocols.
  • FIG. 2a it is a schematic diagram of a user plane protocol stack when an LTE eNB is connected to an EPC.
  • the protocol layers in the protocol stacks of the UE and the LTE eNB are respectively from top to bottom: the Packet Data Convergence Protocol (PDCP) layer, and the Radio Link Control (Radio Link Control). RLC) layer, Medium Access Control (MAC) layer, and Physical layer (Physical, PHY).
  • PDCP Packet Data Convergence Protocol
  • RLC Radio Link Control
  • MAC Medium Access Control
  • Physical layer Physical layer
  • the PDCP layer can be used to perform services such as security, header compression, and encryption.
  • the PDCP layer may exist in multiple PDCP entities, and each PDCP entity carries data of one RB.
  • the PDCP layer is also used to configure and ensure that the data submitted upward is ordered (that is, data is submitted in order).
  • the RLC layer is used to perform services such as fragmentation, reassembly, and retransmission.
  • the RLC layer may exist in multiple RLC entities, and each RLC entity may provide services for each PDCP entity.
  • the MAC layer is used to provide data transmission services for services on logical channels, and perform such services as scheduling, hybrid ARQ (HARQ) acknowledgement and negation.
  • HARQ hybrid ARQ
  • the PHY layer is used to receive data from the MAC layer, and encode and transmit the data.
  • FIG. 2b a schematic diagram of a control plane protocol stack when an LTE eNB is connected to an EPC is shown.
  • the protocol layers in the protocol stacks of the UE and the LTE eNB are from top to bottom: non-access (NAS) layer, radio resource control (RRC) layer, and PDCP layer.
  • NAS non-access
  • RRC radio resource control
  • PDCP packet data convergence protocol
  • the RRC layer is used to perform functions such as message broadcasting, paging, RRC link establishment, radio bearer control, mobility, and UE measurement reporting control.
  • the NAS layer is used to perform functions such as authentication, mobility management, and security control.
  • the data after each layer processes the data is called Protocol Data Unit (PDU) in this layer.
  • PDU Protocol Data Unit
  • SDU Service Data Unit
  • the data input by the PDCP layer to the RLC layer is called PDCP PDU for the PDCP layer; it is called RLC SDU for the RLC layer.
  • FIG. 2c a schematic diagram of a user plane protocol stack when an eLTE eNB is connected to the 5GC is shown.
  • SDAP Service Data Adaptation Protocol
  • the SDAP layer is used to map each quality of service flow (QoS flow) from the 5GC to a wireless data bearer (Data Radio Bearer, DRB) of the wireless access layer, that is, to correspond to the QoS flow according to the service attribute corresponding to the QoS flow.
  • the data packet is transmitted on the corresponding DRB.
  • the SDAP layer can be responsible for adding QoS flow identifiers for uplink and downlink data packets.
  • the RB is divided into a signaling radio bearer (Signalling Radio Bearer, SRB) and a data radio bearer (Data Radio Bearer, DRB).
  • SRB can be used to transmit RRC messages and NAS messages;
  • DRB can be used to transmit service data.
  • each RB may correspond to one logical channel, and each RLC entity may be considered to correspond to one logical channel.
  • the EPC and the LTE base station can establish a GPRS tunnel protocol (GPRS Tunnelling Protocol) based on the Evolved Universal Terrestrial Radio Access Radio Access Bearer (Evolved Universal Terrestrial Radio Access-Radio Access Bearer, E-RAB) granularity , GTP) data tunnels, and uplink and downlink data transmissions are carried out in accordance with E-RAB granularity GTP tunnels.
  • E-RAB Evolved Universal Terrestrial Radio Access-Radio Access Bearer
  • GTP Evolved Universal Terrestrial Radio Access-Radio Access Bearer
  • the LTE base station and the UE establish a corresponding DRB transmission according to the E-RAB, that is, the E-RAB and the DRB correspond one-to-one.
  • the PDCP layer protocol corresponding to each DRB between the LTE base station and the UE uses the LTE PDCP protocol
  • the RLC / MAC / PHY layer uses the LTE RLC / MAC / PHY protocol.
  • Each downlink data packet will carry the corresponding flow ID and whether it has reflection characteristics.
  • the reflection characteristic refers to whether the UE can derive an uplink packet from a mapping relationship between a downlink packet attribute (such as a source IP address, a source port, a destination IP address, a destination port, and a transport layer protocol number, etc.) and a flow ID.
  • the mapping relationship between flow IDs is not limited to the 5GC.
  • the corresponding PDCP layer should use the NR PDCP protocol, and the SDAP layer is added before the NR PDCP layer.
  • RLC / MAC / PHY uses LTE RLC / MAC / PHY protocol.
  • the PDCP layer or SDAP layer of the terminal will pass the downlink data correctly received in the source cell or source base station to the upper layer.
  • the source cell or source base station transfers the downlink data that is not sent correctly to the source core network.
  • the source core network then transfers the corresponding downlink data to the target core network.
  • the target core network then transfers to the target cell or target base station, or the source cell or
  • the source base station directly transfers the downlink data that is not sent correctly to the target cell or the target base station, and the target cell sends the downlink data packet to the terminal in the new radio bearer.
  • the source cell or source base station retransmits data packets that are not acknowledged by the terminal through the target cell.
  • the target cell redistributes a sequence number in the wireless protocol for these packets, and the PDCP layer or SDAP layer of the UE
  • the data packets received by the cell are sent to the upper layer, regardless of whether they are out of order. For example, data packets 1, 3, and 5 are submitted to the upper layer.
  • these data packets received from the target cell are submitted to the upper layer.
  • data packets 2 and 4 are submitted to the upper layer, so that the upper layer of the UE receives these data packets out of order. For example, data packets 1, 3, and 5 are received first, and then data packets 2 and 4 are received.
  • the network elements mainly involved in the technical solution of the embodiment of the present application include: a terminal, an EPC, a 5GC, an LTE eNB, and an eLTE eNB.
  • EPC and 5GC represent two different core networks.
  • the LTE eNB is connected to the EPC, which is the 4G core network, and provides wireless access services for the terminal.
  • the eLTE eNB is connected to the 5GC, which is the 5G core network, and provides the terminal with wireless access service.
  • the terminal is switched between the EPC and the 5GC, and includes: the terminal is moved from the EPC to the 5GC, or the terminal is moved from the 5GC to the EPC.
  • the LTE eNB located in the core network EPC is called the source base station, and the corresponding core network EPC is called the source core network; the eLTE eNB located in the core network 5GC is called the target base station, corresponding The core network 5GC is called the target core network.
  • the source core network is 5GC
  • the source base station is eLTE eNB
  • the target core network is EPC
  • the target base station is LTE eNB.
  • the source base station and the target base station may be the same base station, that is, the base station is connected to the EPC and also to the 5GC.
  • an LTE eNB is connected to an EPC and a gNB is connected to a 5GC.
  • Corresponding network elements include: terminal, EPC, 5GC, LTE eNB, and gNB.
  • the LTE eNB connected to the core network EPC is called the source base station, and the corresponding core network EPC is called the source core network; the gNB connected to the core network 5GC is called the target base station, and the corresponding core The 5GC is called the target core network.
  • the source core network is 5GC
  • the source base station is gNB
  • the target core network is EPC
  • the target base station is LTE eNB.
  • the source base station and the target base station can be the same base station, that is, the base station is connected to both the EPC and the 5GC.
  • a base station is used as a description object instead of a source cell and a target cell as description objects in these descriptions.
  • the source cell and the target cell may still be used as description objects.
  • this application provides a data transmission method.
  • the method can be applied to a source base station. Specifically, the method includes:
  • Step 301 The source base station determines the first data and a wireless air interface protocol sequence number of a data unit used to carry the first data.
  • the first data includes: data that the source base station and the terminal have not correctly received during the data transmission process and / or out-of-order data that the source base station receives from the terminal.
  • the first data sent by the source base station to the target base station includes uplink data and / or downlink data.
  • the downlink data corresponds to a wireless air interface protocol sequence number, for example, a data packet of a PDCP layer sequence number (SN), that is, the first data may be divided into multiple data units or data packets, and each data unit or data The packet corresponds to an SN number; and the SN number is allocated by the source base station.
  • a wireless air interface protocol sequence number for example, a data packet of a PDCP layer sequence number (SN)
  • SN PDCP layer sequence number
  • the first data that the source base station allocates the SN number includes: data sent by the source base station to the terminal but not receiving terminal feedback (haven't beacknowledged by the UE), and / or, the source base station has allocated The SN number, but the data has not been sent to the terminal.
  • the first data is in the form of PDCP SDU, that is, a data packet that does not include the PDCP header.
  • the source base station sends the PDCP SDU to the target base station, and also includes the first data indicating The corresponding SN of the data unit or data packet at the source base station.
  • the uplink data also includes out-of-order data received by the source base station from the terminal.
  • the out-of-order refers to data packets that were not correctly received by the source base station before the source base station correctly received the data packets from the terminal.
  • the sequence of the data packets generated by the application layer of the terminal is data packets 1, 2, 3, 4, and 5.
  • the source base station only correctly received data packets 1, 3, and 5, and the terminal sent data packets 2, 4 at the source base station.
  • the source base station did not receive data packets 2 and 4 correctly, so for the source base station, data packets 3 and 5 are out of order because data packets 2 and 4 were not received.
  • the source base station does not send these out of order data packets to the target base station.
  • the source base station directly submits these correctly received out of order data packets to the core network, so these data packets are out of order.
  • the terminal sends only those data packets in the target cell that are not sent in the source cell (for example, the terminal will not send in the target cell the data packets 2, 4 that the terminal has sent but have not been correctly received by the source base station).
  • the data packets that are not correctly received by the source cell will be discarded (for example, the above data packets 2 and 4), resulting in packet loss.
  • the terminal is switched from EPC to 5GC as an example.
  • the first data is described in the form of PDCP and SDU, that is, the header that does not include PDCP is sent to the target base station, and it also includes an indication of the first
  • the data unit or packet of a data corresponds to the SN number of the source base station.
  • Step 302 The source base station sends the first data and the wireless air interface protocol sequence number to a target base station.
  • the core network to which the target base station is connected is different from the core network to which the source base station is connected.
  • the source base station and the target base station are the source base station and the target base station during the handover process of the different core networks of the terminal.
  • the sending, by the source base station, the first data and the wireless air interface protocol sequence number to the target base station includes: the source base station sends the unscheduled data in the first data to the target base station through a first tunnel.
  • the terminal confirms the correctly received data and the wireless air interface protocol sequence number; and / or, sends the data from the terminal and the wireless air interface protocol in the first data to the target base station through a second tunnel serial number.
  • the wireless air interface protocol sequence number may be carried in a GTP-U (GTP User Plane, GTP-U) header or an extension header.
  • GTP-U GTP User Plane, GTP-U
  • the first tunnel and the second tunnel may be different tunnels.
  • the source base station sends the downlink data packet and the corresponding SN number in the first data to the target base station through a tunnel on the user plane (that is, the first tunnel).
  • the source base station sends the uplink data packet and the corresponding SN number in the first data through the tunnel on the user plane (that is, the second tunnel).
  • the source base station will notify the target base station which uplink data packets in the SN number range are received out of order through control plane signaling.
  • Step 303 The target base station receives the first data and the wireless air interface protocol sequence number from the source base station.
  • the wireless air interface protocol serial number is a serial number of a data unit determined by the source base station to carry the first data.
  • the wireless air interface protocol sequence number may be a data unit of a first data or an SN number of a data packet.
  • Step 304 The target base station sends the first data and the wireless air interface protocol sequence number to the terminal.
  • the terminal since the source base station includes the data of the wireless air interface protocol sequence number of the data unit in the data sent to the target base station, and the wireless air interface protocol sequence number can be identified by the terminal, the terminal is correct from the source base station
  • the received and confirmed data packets have consistent sequence numbers, so the terminal can correctly receive from the source base station according to these sequence numbers, and those from the target base station and transferred from the source base station to the target base station are not terminated at the source base station. Confirm that the received packets are sorted correctly to ensure that the packets are submitted in order.
  • the method further includes: the source base station determines second data, where the second data includes the source base station receiving from the source core network to be sent to the terminal during the core network handover process. data.
  • the terminal switches from EPC to 5GC.
  • the EPC's LTE eNB receives from the EPC the data packets that need to be sent to the terminal. These data packets have not been assigned the wireless air interface protocol sequence number, that is, the SN number.
  • the source base station will notify the target base station through control plane signaling. For these data packets, the SN number needs to be assigned next.
  • the allocation principle can be based on the sequence number of the data packet assigned by the source base station to the terminal, and then continue to assign the next serial number.
  • the target base station is instructed to correspond to the SN number of the next data packet that is not assigned an SN number.
  • the next sequence number may be indicated by a downlink count count value, where the count value includes the SN number and the superframe number of the PDCP of the corresponding packet.
  • the source base station allocates sequence numbers for the data packets in the first data from SN_0 to SN_100.
  • the target base station continues to allocate sequence numbers starting from SN_101, so that the target base station allocates these
  • the terminal can correctly sort the data.
  • the method further includes: the source base station sends the second data to the target base station, so that the target base station continues to allocate the second data according to a wireless air interface protocol sequence number corresponding to the first data A wireless air interface protocol sequence number of a data unit of the second data.
  • a specific sending manner includes: the source base station sends the second data to a target base station through a tunnel (such as a first tunnel) on a user plane.
  • a tunnel such as a first tunnel
  • the method before step 302: before the source base station sends the first data and the wireless air interface protocol sequence number to the target base station, the method further includes:
  • Step 401 The source base station configures first radio bearer information for the terminal, where the first radio bearer information is used to establish a radio bearer between the source base station and the terminal.
  • Step 402 The source base station sends the first radio bearer information to the target base station.
  • the first radio bearer information includes configuration information of the radio bearer.
  • the configuration information of the radio bearer includes at least one of a radio bearer identifier, PDCP layer information configured by the source base station for the UE, and RLC layer information configured by the source base station for the UE.
  • the source base station may carry the first radio bearer information in a handover request message sent to the target base station.
  • the source base station may also carry the first radio bearer information in a handover request message to the source core network, and then the source core network notifies the target core network, and the target core network carries the first radio bearer information in the handover request message to the target core network.
  • a radio bearer may be carried.
  • a message (a handover request or a handover request message) from the source base station to the target base station carries an instruction for requesting data transfer.
  • the target base station receives the first radio bearer information, determines the second radio bearer information according to the first radio bearer information, and generates a confirmation message, and then the target base station sends the confirmation message to the source base station.
  • the confirmation message carries the second radio bearer information.
  • the confirmation message also carries tunnel information that the target base station receives the first data transferred from the source base station.
  • the tunnel information includes the transport layer address and GTP-TEID.
  • the tunnel information can also distinguish the tunnel information corresponding to the received uplink and downlink data.
  • the confirmation message may be a handover request confirmation message sent by the target base station to the source base station; the confirmation message may also be a handover request confirmation message sent by the target base station to the target core network, and then the target core network sends a message again To the source core network, the message carries the second radio bearer information and the tunnel information allocated by the target core network.
  • the tunnel information allocated by the target core network refers to the tunnel information that the target core network receives the transferred data from the source core network.
  • the source core network carries the second radio bearer information and the tunnel information allocated by the source core network in a handover command message to the source base station.
  • the tunnel information allocated by the source core network refers to the tunnel information that the source core network receives the transferred data from the source base station.
  • the method further includes: the target base station generates third radio bearer information, where the third radio bearer information includes configuration information of new data that the terminal interacts with a core network connected to the target base station, for example, the configuration information includes the second wireless bearer Bearer, used to configure the terminal with radio resources capable of carrying new data that interacts with the target core network.
  • the new data is data generated by the application layer of the UE after the handover to the target core network and data received from the target core network and not transferred from the source base station.
  • Step 403 The source base station receives a confirmation message fed back by the target base station.
  • the confirmation message may carry information indicating a second radio bearer between the target base station and the terminal.
  • the second radio bearer information includes configuration information of the radio bearer, and the radio bearer may be used for the bearer.
  • the first data, and the radio bearer may be the same as or different from the radio bearer in the first radio bearer information. For example, the radio bearer has the same radio bearer ID.
  • the second radio bearer information may also be used to indicate acceptance of the first data.
  • the confirmation message includes an RRC reconfiguration message configured by the target base station for the terminal, and the RRC reconfiguration message includes a cell ID and the like that the terminal needs to access in the target base station.
  • the source base station After receiving the confirmation message from the target base station, the source base station forwards the RRC reconfiguration message in the confirmation message to the terminal.
  • the RRC reconfiguration message in the confirmation message may carry the second radio bearer information.
  • the RRC reconfiguration message in the confirmation message further includes information for the third radio bearer.
  • Step 404 The source base station sends configuration information to the terminal.
  • the configuration information may use RRC reconfiguration information.
  • the RRC reconfiguration message may be the RRC reconfiguration message received by the source base station from the target base station in step 403.
  • the configuration information may also be sent to the terminal through a handover notification message.
  • the source base station sends radio bearer information to the target base station to help the target base station configure its radio bearer with the terminal, and then uses the radio bearer to transmit the first data, so that both the target base station and the terminal can continue to use
  • the radio bearer in the source base station is configured to transmit or store the first data, to ensure that the first data can continue to retain and use the sequence number before the target base station, thereby ensuring that the data packets corresponding to the first data are delivered in order.
  • the target base station determines the second radio bearer information according to the first radio bearer information from the source base station and feeds back a confirmation message to the source base station is described in detail.
  • the method provided in this embodiment is how the source base station and the terminal and the target base station and the terminal handle the handover data between the source base station and the target base station, such as downlink data packets that have not been correctly received by the UE.
  • the method includes the following steps:
  • Step 501 The source base station generates a first request message, such as a handover request message, where the first request message includes a radio bearer configuration configured by the source base station for the UE.
  • the first request message further includes a handover type indication.
  • the handover type indication is used to indicate a handover between different base stations in a core network of the same standard, or to indicate a handover between two base stations corresponding to a core network of a different standard.
  • the handover type indication may further indicate whether the UE is handed over from 5GC to EPC or from EPC to 5GC.
  • the radio bearer configuration may be carried through the first radio bearer information and used to establish a radio bearer between the source base station and the terminal.
  • the radio bearer configuration includes a DRB identifier, NR PDCP configuration information and NR SDAP configuration information corresponding to the DRB.
  • the NR SDAP configuration information includes: a mapping relationship between a DRB configured by the source base station for the UE and a QoS flow, that is, an instruction indicating which QoS flow the UE or the source base station puts on which DRB, in order to utilize the corresponding DRB transmits Qos flow. For example, there are three QoS flows: flow 1, flow 2, and flow 3.
  • the source base station will notify the UE to place the uplink data packets of flow 1 and flow 2 on DRB1 through the NR SDAP configuration information, and place the uplink data packets of flow 3 on On DRB2, and carry out the corresponding transmission.
  • the NR SDAP configuration information also includes at least any one of the following: a PDU session ID carried by the DRB, whether SDAP packet headers are configured for the SDAP uplink and downlink, and whether the DRB is the default DRB.
  • the PDU session ID refers to an identifier of the PDU session.
  • the default DRB means that the UE maps the QoS flow to the default DRB when the network side does not notify the terminal to which DRB a certain QoS flow packet corresponds.
  • the network side does not notify the terminal which DRB the uplink data packet of a certain QoS flow corresponds to.
  • the network side does not indicate the mapping relationship between the identifier corresponding to the QoS flow and the DRB identity through an RRC message, and does not pass the user plane. Indicate which DRB the uplink packets of this QoS flow are mapped to.
  • the radio bearer configuration includes a DRB configuration configured by the source base station for the UE.
  • the DRB configuration specifically includes a DRB identifier and PDCP information configured by the source base station corresponding to the DRB for the UE.
  • the first request message may further include: a mapping relationship between services of different core networks, or a request to ensure a service corresponding to an EPS bearer in some EPCs and a QoS in 5GC between a source core network and a target core network.
  • One-to-one request cells corresponding to the service corresponding to the flow For example, when switching from EPC to 5GC, the source cell can request between the source core network and the target core network to ensure that all data packets in some E-RAB IDs are mapped to the same QoS flow ID (such as E-RAB ID1 and Qos flow ID2 corresponds, E-RAB ID2 corresponds to QoS flow ID1).
  • the EPS bearer refers to a service flow in 4G that is used to identify service flows with the same service processing characteristics (such as a scheduling policy and a queue management policy).
  • the smallest granularity of service classification in EPC is the EPS bearer.
  • the core network will allocate an E-RAB identifier to the EPS bearer to the base station.
  • the QoS flow refers to a service flow in 5G where the UE has the same service processing characteristics (such as a scheduling policy and a queue management policy).
  • the smallest granularity of service classification in 5GC is QoS flow.
  • the core network 5GC will assign a QoS flow ID to the base station for each QoS flow.
  • the first request message further includes an identifier of the target base station, such as the target base station ID.
  • the first request message further includes: an instruction for requesting data transfer.
  • the first radio bearer information may be contained in a container, or may be directly carried in a message cell manner, or may be partially carried in a container form. Some are carried in message cells.
  • the container means that the information carried in the container can be transmitted to the target cell in a transparent form through the core network, that is, the core network does not need to know the meaning of the specific content in the message.
  • the source base station sends the first request message to the source core network.
  • Step 502 The source core network receives a first request message from the source base station, selects a target core network, and sends a part of the content in the first request message to the target core network through a second request message.
  • a part of the first request message includes at least one of the following: an indication of a handover type, a radio bearer configuration configured by the source base station for the UE, a service mapping relationship between different core networks, and an identity of the target base station.
  • Step 503 The target core network receives a second request message from the source core network, and sends a part of the content in the second request message to the target base station through a third request message.
  • the target core network can determine the target base station and send the third request message.
  • a part of the content in the second request message includes at least any one of the following: an indication of a handover type, a radio bearer configuration configured by the source base station for the UE, and an indication of requesting data transfer.
  • the third request message may further include service QoS related information notified by the target core network to the target base station to establish.
  • the service QoS related information includes PDU session ID, QoS flow ID, and service quality information corresponding to the QoS flow (such as guaranteed rate, maximum rate, priority, etc.).
  • the target core network is EPC
  • the service QoS related information includes the E-RAB ID and the quality of service information corresponding to the E-RAB.
  • Step 504 The target base station receives a third request message from the target core network, and allocates a corresponding radio resource configuration to the UE according to the content in the third request message, and generates a first confirmation message, such as a handover request confirmation message.
  • the first confirmation message includes second radio bearer information.
  • the corresponding radio resource configuration (ie, the second radio bearer information) allocated for the UE includes at least one of the following: LTE PDCP configuration, NR PDCP configuration, and NR SDAP configuration.
  • the LTE PDCP configuration includes some configurations of the LTE PDCP layer (such as packet loss timer, header compression configuration, PDCP layer sequence number length, etc.); the NR PDCP configuration includes some configurations of the NR PDCP layer (such as packet loss Timer length, header compression configuration, PDCP layer sequence number length, integrity protection configuration, out-of-sequence commit configuration, sequencing timer length, etc.).
  • the target base station determines the radio resource bearer of the UE according to the third request message from the target core network, including: the target base station configures the DRB1_1 for the UE according to the original DRB1 ( For example, the DRB identifier is the same, and the PDCP configuration of the DRB can also be the same.)
  • the DRB1_1 is used to carry data packets that have not been correctly received by the UE. It also includes data packets received by the source base station from the source core network EPC when the UE switches to 5GC.
  • the target base station also generates a DRB2, which includes NR_PDCP configuration information and is used to carry data in the core network 5GC.
  • the target base station also allocates multiple DRBs for the UE, some of which use LTE PDCP configuration, and some use NR PDCP and NR SDAP configuration.
  • the wireless resource configuration further includes at least one of the following: the correspondence between the E-RAB ID, the DRB ID, the DRB ID, and the QoS flow ID, and the correspondence between the DRB ID and the PDU session ID.
  • the target base station retains the original DRB1 and the configuration information of the DRB1, and generates DRB2.
  • the newly generated DRB2 includes the LTE PDCP layer and the LTE RLC layer. It is used to carry the data in the core network EPC.
  • the first confirmation message also carries tunnel information that the target base station receives the first data transferred from the source base station.
  • the tunnel information includes a transport layer address and a GTP-TEID. Further, the tunnel information may further distinguish between receiving tunnel information corresponding to uplink data and downlink data.
  • the first acknowledgment message further includes: the target base station's acceptance of radio bearers sent by the source base station, such as indicating which radio bearers are accepted, and may also indicate which radio bearers are not accepted.
  • the method further includes: the target base station sends the second radio bearer information allocated for the UE to the target core network.
  • the second radio bearer information may be carried by a first confirmation message.
  • the second radio bearer information includes third radio bearer configuration information.
  • the specific manner in which the target base station sends the second radio bearer information (including the third radio bearer configuration information) to the target core network includes: one way includes sending in the form of a container; the other way can also directly send the message It can be carried in the form of cells; or, it can also be carried in the form of a container in a part and in a mixed manner in a part of a message cell.
  • one way includes sending in the form of a container; the other way can also directly send the message It can be carried in the form of cells; or, it can also be carried in the form of a container in a part and in a mixed manner in a part of a message cell.
  • Step 505 The target core network receives a first confirmation message from the target base station, and generates a second confirmation message, where the second confirmation message includes at least a part of the first confirmation message, and sends the second confirmation message to the source core network. Sending the second confirmation message.
  • This step 505 is the same as the existing process.
  • the second confirmation message may further include data transfer tunnel information, and the data transfer tunnel message includes a transport layer address (that is, an IP address), a GTP-TEID, and the like.
  • a transport layer address that is, an IP address
  • GTP-TEID GTP-TEID
  • the second confirmation message may further include: a radio resource configuration allocated by the target base station to the UE, and the radio resource configuration may include at least one of an LTE PDCP configuration, an NR PDCP configuration, and an NR SDAP configuration.
  • the radio resource configuration may be different from the radio resource configuration configured by the source base station for the UE, that is, the radio resource configuration may include only different information from the radio resource configuration configured by the source base station for the UE.
  • Step 506 The source core network receives a second confirmation message from the target core network, generates a third confirmation message, and sends the third confirmation message to the source base station, where the third confirmation message includes at least the second confirmation message. Confirm part of the message.
  • the source core network allocates data transfer tunnel information on the source core network side for the admitted PDU session, QoS flow, or DRB according to the admission in the second confirmation message, and configures the data transfer tunnel information in the third confirmation message. in.
  • the source core network and the target core network use the same data tunnel information, for example, the user plane of the source core network and the user plane of the target core network are in the same module.
  • the third confirmation message further includes at least one of the following second confirmation messages: the target base station accepts the service QoS of the target core network, the target base station accepts the radio bearer configuration sent by the source base station, and the target Radio resource allocation allocated by the base station to the UE.
  • the third confirmation message may carry which DRBs are accepted by the target cell and which are rejected. If the terminal switches from EPC to 5GC, the message may carry which E-RABs are accepted by the target cell and which are rejected. Or it can carry information such as which QoS flow is accepted by the target cell and which is rejected.
  • the message type of the third confirmation message may be a handover command.
  • Step 507 The source base station receives a third confirmation message from the source core network, generates a handover notification, and sends the handover notification to the UE.
  • the handover notification includes a radio resource configuration allocated by the target base station to the UE in the third confirmation message.
  • the handover notification may be an RRC reconfiguration message.
  • the RRC reconfiguration message includes: after the UE switches to the target base station under the target core network, the target cell or the target base station configures the second radio bearer information and / or the third radio bearer information for the UE.
  • Step 508 The source base station sends the data and the wireless air interface protocol sequence number corresponding to the data unit of the data to the target base station.
  • the data transmission in step 508 includes transmission in two directions of uplink data and downlink data. The data transmission in these two directions will be described below.
  • the data includes first data and second data.
  • the first data is data having an SN number assigned by the source base station, and the source base station and the terminal have not been correctly received by the terminal during data transmission.
  • the second data is: the data received by the source base station to be sent to the terminal during the handover of the core network, the data has not been assigned an SN number, so the target base station needs to continue to The second data is assigned an SN number.
  • the source base station when the source base station transfers these data packets, it also transfers these data packets in order, for example, according to the sequence of the source base station receiving from the source core network.
  • the data that is not confirmed to be correctly received by the terminal includes: the source base station has allocated the PDCP and SDU of the SN (the PDCP layer has allocated the SN to the PDCP and the SDU) and sends it to the terminal, but does not receive a data packet fed back by the terminal, And / or, the source base station has allocated a data packet with an SN number, but has not yet sent it to the terminal.
  • the source base station sends the first data, the second data, and their corresponding SN numbers to a target base station (target cell) through a DRB or an E-RAB tunnel.
  • the method further includes: the source base station sends at least one end marker packet to the target base station or the target cell, and the end marker packet It is used to instruct the source base station to end transferring data over the tunnel, that is, no subsequent data is transferred to the target base station over the tunnel.
  • the source base station receives an end marker from the source core network, the source base station sends the at least one end identification packet to the target base station or the target cell.
  • the method further includes: the source base station sends a status transfer message to the target base station, the status transfer message is used to indicate the receiving status of the uplink PDCP SN and the super frame number and the sending of the downlink PDCP SN and the super frame number status.
  • the state transfer message may be sent to the target base station through the source core network and the target core network.
  • the state transfer message carries at least one of the following: the DRB ID that the source base station needs to perform data transfer, and the next count value assigned by the target base station to the DRB corresponding to the downlink data packet, and the count value includes the PDCP of the corresponding packet.
  • the DRB ID that the source base station needs to perform data transfer
  • the count value includes the PDCP of the corresponding packet.
  • SN number and super frame number and the receiving condition of the source base station ’s corresponding uplink data packet in the DRB (the count value corresponding to the first PDCP packet that was not received correctly, the count value includes the SN number and super frame number of the PDCP corresponding to the packet, And uplink reception of other data packets after the PDCP packet).
  • the status transfer message is generally sent before the source base station transfers the data packet to the target base station.
  • the data transmitted from the source base station to the target base station includes:
  • First data a data packet that has not been correctly received by the terminal and carries a PDCP sequence number SN, that is, PDCP SDU with SN, for example, SN_n, SN_n + 1, SN_n + 2.
  • the second data a new data packet from the EPC, and the second data does not carry PDCP SN, that is, PDCP DU without SN.
  • PDCP SN that is, PDCP DU without SN.
  • the target base station can continue to transmit to the UE through DRB1_1 (using LTE PDCP).
  • the data transmitted to the target base station further includes: third data.
  • the third data is new data from 5GC (that is, data packets delivered in 5GC format), and these data packets can be transmitted through DRB2 (using NR PDCP). For example, the three packets of flow 1 flow 1_1 / flow1_2 / flow 1_3.
  • the target base station obtains the first data, the second data, the end identifier, and the third data.
  • the target base station first sends the data packet in the first data in DRB1_1 configured for the UE, and then sends the second data in DRB1_1 configured for the UE. Packets in the data.
  • the target base station carries the acquired third data flow1_1 / flow1_2 / flow1_3 in DRB2.
  • the target base station since the target base station uses the LTE PDCP DRB, it can continue to use the PDCP SN number assigned by the source base station to the DRB in the DRB.
  • the target base station then transmits data to the terminal through the DRB, and the terminal can identify and follow the SN sequence. Submit the data to the upper layer to ensure that the data packets are submitted in order.
  • the data transmitted by the source base station (for example, eLTE eNB) to the target base station (LTE eNB) includes: first data, the first data is a PDCP SDU that has not been correctly received by the terminal and carries an SN number.
  • the source base station includes a source cell
  • the target base station includes a target cell
  • these data packets can be transmitted to the target base station through a DRB or E-RAB tunnel.
  • the data transmitted from the source base station to the target base station further includes: the source base station sends a new QoS flow data packet from the source core network 5GC, and the QoS flow is accepted by the target cell for data forwarding.
  • the source base station transmits the new QoS flow data packet to the target base station through the DRB or E-RAB tunnel, or transmits the new QoS flow packet to the target base station through the PDU session tunnel.
  • the source base station After the source base station receives one or more end markers from the source core network, if a PDU session tunnel is established between the source base station and the target base station, the source base station transfers these end markers to the target through the corresponding PDU session tunnel. Base station. If a DRB tunnel is established between the source base station and the target base station, when no other data packets need to be transferred to the target base station through the DRB tunnel, the source base station will generate one or more end markers and send it to the target base station through the corresponding DRB tunnel. .
  • the source base station copies these end markers to each tunnel of the source base station and the target base station (including DRB tunnel or E-RAB tunnel or PDU session tunnel). At least one of).
  • the method further includes: the source base station sends a status transfer message to the target base station, the status transfer message is used to indicate the receiving status of the uplink PDCP SN and the super frame number and the sending status of the downlink PDCP SN and the super frame number.
  • the state transfer message may be sent to the target base station through the source core network and the target core network.
  • the state transfer message carries at least one of the following: a DRB ID that the source base station needs to perform data transfer, and a next count value assigned by the target base station in the DRB corresponding to the downlink data packet, and the count value includes the PDCP of the corresponding packet SN number and superframe number, and the receiving status of the source base station ’s corresponding uplink data packet in the DRB.
  • the count value includes the PDCP SN number and After the super frame number and the PDCP packet, the uplink receiving conditions of other data packets.
  • the status transfer message is generally sent before the source base station transfers the data packet to the target base station.
  • the target base station may use a DRB using NR PDCP and NR SDAP to send the data; for new data transmitted from the target core network to the target base station (that is, delivered in the EPC format) Data packet), DRB transmission using LTE PDCP can be used.
  • the DRB can continue to use the PDCP SN number assigned by the source base station to the DRB in the DRB, and the terminal can submit data to the upper layer in the order of the SN to ensure that the data packets are submitted in order.
  • the process of transmitting data from the source base station (or source cell) to the target base station in step 508 specifically includes:
  • the data to be transmitted includes first data, and the first data includes: out-of-order data received by the source base station from the terminal, and the out-of-order refers to data packets that the source base station correctly receives from the terminal before Some packets are not correctly received by the source base station.
  • these data packets can be transmitted to the target base station through a DRB or E-RAB tunnel.
  • These data packets are transferred to the target base station in the form of PDCP SDU, and the SN number corresponding to the PDCP SDU is carried during the transfer.
  • the method for transferring uplink and downlink data between the source base station and the target base station includes the following two methods:
  • One way is: directly between the target base station and the source base station, that is, the source base station directly sends data and a serial number corresponding to the data to the target base station.
  • the target base station and the source base station indirectly through the source core network and the target core network, that is, the source base station sends data and the serial number corresponding to the data to the source core network, and the source core network receives these data and The serial number corresponding to the data is sent to the target core network, and the target core network sends the data and the serial number to the target base station.
  • which transmission method is adopted may be determined by the internal configuration of the source core network and the target core network, or which transmission method may be selected according to the protocol.
  • the method further includes:
  • Step 509 The terminal UE receives a handover notification from the source base station and sends a handover completion message to the target base station, indicating that the UE is ready for data transmission.
  • the UE determines a target cell according to the target cell ID carried in the handover notification, and then establishes a communication connection with the target cell.
  • the handover notification may be an existing message type, such as an RRC reconfiguration message.
  • the RRC reconfiguration message includes radio bearer configuration information configured by the target cell or the target base station for the UE.
  • the radio bearer configuration information includes second radio bearer information and / or third radio bearer information.
  • Step 510 Data transmission is performed between the target base station and the terminal UE.
  • the data transmission includes: data transmission in a downlink direction, and data transmission in an uplink direction.
  • the two types of radio bearer information configured on the target base station side one is the radio bearer in the second radio bearer configuration information, which is used to carry the first data and / or the second data transferred from the source base station or the source cell.
  • the other is the radio bearer in the third radio bearer configuration information, which is used to carry the 5GC new data packet, namely SDAP SDU.
  • the second radio bearer configuration information may be the same as or different from the first radio bearer information configured by the source base station for the UE.
  • the target base station In order to ensure that the UE submits data to the upper layer in the order of the data packets, the target base station (target cell) first sends the first data and / or the second data to the UE through the radio bearer in the second radio bearer configuration information, and waits for the UE to confirm the correct reception. After the data packets are obtained, the new data packet from the 5GC is sent to the UE through the radio bearer in the third radio bearer configuration information.
  • a process in which the target base station determines whether the first data and / or the second data is correctly received by the UE includes:
  • a possible implementation manner is: the target base station determines the reception condition of the UE by using the state information of the RLC layer. Further, after receiving the data packet from the target base station, the UE sends the RLC state information to the target base station.
  • the RLC status information indicates the data packet received by the UE; after receiving the status information fed back by the UE, the target base station can determine whether the data packet is received correctly according to the indication of the status information. For example, each data packet includes an identifier, which is used to indicate that the UE correctly receives the data packet sent by the target base station.
  • the target base station judges whether the data packet is correctly received by the UE through the ACK of the MAC layer. Specifically, if the target base station receives an ACK from the UE, the UE considers that the UE has correctly received the data packet; otherwise, it considers that the UE has not correctly received the data packet.
  • the way in which the protocol layer above the wireless protocol layer of the UE receives data packets becomes the way in which it receives data packets when connected to 5GC.
  • the downlink data received by the UE from the radio bearer in the second radio bearer information should be submitted to the upper layer in a manner of being connected to the 5GC.
  • the UE determines which SDAP entity submits the downlink data packet received from the radio bearer in the second radio bearer information to the upper-layer interface according to the corresponding relationship between the E-RAB ID and the PDU session ID / QoS ID.
  • the upper layer does not need to inform the package of the special reflection information and flow ID.
  • the UE determines which SDAP entity to submit the downlink data packet received from the radio bearer in the second radio bearer information to according to the corresponding relationship between the E-RAB ID and the PDU session ID / QoS ID. The SDAP entity Then, these downlink data packets received from the radio bearer in the second radio bearer information are submitted to the upper layer, and when the SDAP entity submits the downlink data packets to the upper layer, it is not necessary to notify the packet of special reflection information and flow ID.
  • Radio bearer information configured on the target base station side, one is the radio bearer in the second radio bearer configuration information for carrying the first data and / or the second data transferred from the source base station or the source cell, and the other It is the radio bearer in the third radio bearer configuration information, and is used to carry the new data packet of the EPC, namely LTE PDCP and SDU.
  • the target base station In order to ensure that the UE submits data to the upper layer in the order of the data packets, the target base station (target cell) first sends the first data and / or the second data to the UE through the radio bearer in the second radio bearer configuration information, and waits for the UE to confirm the correct reception. After the data packets are obtained, the new data packet of the EPC is sent to the UE through the radio bearer in the third radio bearer configuration information.
  • a process in which the target base station determines whether the first data and / or the second data is correctly received by the UE is the same as that described in the process of the UE switching from the EPC to the 5GC, and details are not described herein again.
  • the way in which the protocol layer above the wireless protocol layer of the UE receives data packets becomes the way in which it receives data packets when connected to the EPC.
  • the downlink data received by the UE from the radio bearer in the second radio bearer information should be submitted to the upper layer in a manner of being connected to the EPC.
  • the UE determines which LTE PDCP entity submits the downlink data received from the radio bearer in the second radio bearer information to the interface of the upper layer according to the corresponding relationship between the E-RAB ID and the PDU session ID / QoS ID.
  • the upper layer does not need to inform the package of the special reflection information and flow ID.
  • the UE determines to which LTE PDCP entity the downlink data packet received from the radio bearer in the second radio bearer information is submitted according to the corresponding relationship between the E-RAB ID and the PDU session ID / QoS ID.
  • the entity then submits the downlink data packets received from the radio bearer in the second radio bearer information to the upper layer.
  • the LTE PDCP entity submits these downlink data packets to the upper layer, it does not need to notify the packet of special reflection information and flow ID.
  • step 510 data transmission between the target base station and the UE includes: data transmission during the UE handover from EPC to 5GC, and data transmission during the UE handover from 5GC to EPC.
  • the UE For the data transmission of the UE switching from EPC to 5GC: Specifically, the UE retransmits the LTE PDCP SDUs that are not correctly received by the source cell to the target base station through the radio bearer in the second radio bearer information.
  • the target base station confirms have been received correctly, and send the newly-added data packet, ie, SDAP SDU, to the target base station through the radio bearer in the third radio bearer information.
  • the data transmission for the UE switching from 5GC to EPC process specifically includes: the UE resends the NR PDCP SDUs that are not correctly received in the source cell to the target base station through the radio bearer in the second radio bearer information, optional It is possible to further exclude those NR PDCP SDUs that have been confirmed to have been correctly received by the target base station; and send the upper layer new data packet to the target base station through the radio bearer in the third radio bearer information, that is, LTE PDCP SDU.
  • the UE may transmit the PDCP SDU that was not successfully transmitted in the radio bearer information in the second radio bearer information, and confirm that these data packets are correctly received by the base station, and then transmit a new data packet on the radio bearer in the third radio bearer information.
  • the UE did not successfully transmit the PDCP SDU in the radio bearer information in the second radio bearer information, and at the same time may send an end identifier in the radio bearer in the second radio bearer information, for example, it may pass the SDAP layer or It is indicated by the PDCP layer or the RLC layer, for example, by the bits in the header of these layers, or by a PDU without a payload in these layers, or by the control PDUs in these layers. Further, it can also indicate which QoS flow data packet ends.
  • the UE can simultaneously transmit a new data packet on the radio bearer in the third radio bearer information, that is, the UE does not need to confirm that the data packet transmitted on the radio bearer in the second radio bearer information is correctly received by the base station, and then starts to transmit the data packet on the third radio bearer A new data packet is transmitted on the radio bearer in the message.
  • the data packets submitted by the target base station to the core network should be submitted in the form of connecting to the 5GC.
  • the uplink data received by the target base station from the radio bearer in the second radio bearer information should be submitted to the core network by connecting to the 5GC.
  • the target base station determines the PDU corresponding to the tunnel corresponding to the PDU, and sends the uplink data packet received from the radio bearer in the second radio bearer information to the corresponding relationship between the E-RAB ID and the PDU session ID / QoS flow ID.
  • the target core network 5GC adds a QoS flow ID to each data packet, for example, it is determined according to the corresponding relationship between the E-RAB ID and the PDU session ID / QoS flow ID.
  • the target base station determines which SDAP entity to submit the uplink data packet received from the radio bearer in the second radio bearer information to according to the corresponding relationship between the E-RAB ID and the PDU session ID / QoS ID.
  • the SDAP entity The uplink data packet received from the radio bearer in the second radio bearer information is then submitted to the target core network.
  • a QoS flow ID is added to each data packet, for example, according to The corresponding relationship between the E-RAB ID and the PDU session ID / QoS flow ID is determined.
  • the target base station knows which of the PDCP entity using the LTE PDCP and the upper layer interface according to the corresponding relationship between the E-RAB ID and the PDU ID / Qos ID. Submitted to the core network, and sent to the core network in the GTP-U format of the EPC. Optionally, when submitting to the core network, it is not necessary to carry the flow ID.
  • the data packets submitted by the target base station to the core network should be submitted in the form of connection to the EPC.
  • the uplink data received by the target base station from the radio bearer in the second radio bearer information should be submitted to the core network in a manner of being connected to the EPC.
  • the target base station determines which E-RAB corresponding tunnel is used to send the uplink data packet received from the radio bearer in the second radio bearer information according to the corresponding relationship between the E-RAB ID and the PDU session ID / QoS ID. For the target core network EPC, there is no need to carry the flow ID.
  • the target base station determines which LTE PDCP entity to submit the uplink data packet received from the radio bearer in the second radio bearer information to according to the corresponding relationship between the E-RAB ID and the PDU session ID / QoS ID.
  • the PDCP entity then submits the uplink data packets received from the radio bearers in the second radio bearer information to the target core network, and the LTE PDCP entity submits these uplink data packets to the core network.
  • the target base station first submits the radio bearer data in the second radio bearer information to the target core network, and then submits the radio bearer data in the third radio bearer information to the target core network. For example, after receiving the end marker on the radio bearer in the second radio bearer information, the target base station submits the radio bearer data in the third radio bearer information to the target core network.
  • Step 511 The UE receives data from the target base station and a sequence number corresponding to the data packet, and delivers the data packet to a higher layer in the sequence of the sequence number.
  • the target base station configures the second radio bearer information for the UE by using the first radio bearer information of the source base station, and the DRB in the second radio bearer information is used for the first data transferred from the source base station and / Or second data, and these data retain the SN number assigned by the source base station, so the target base station at the receiving end can send these data packets to the UE through the DRB, thereby ensuring that the packets are not lost, and the UE can switch the core in the sequence of the sequence number All data packets obtained before and after the network are sorted, thereby ensuring that all data packets can be submitted to the upper layer in order.
  • the target base station also establishes third radio bearer information, and the radio bearer in the third radio bearer information is used to carry data for handover to the target core network, so that the data of the target core network can be transmitted on the target base station with a new radio bearer. Transmission to avoid out of order with the data packets in the source core network, and further ensure the orderliness of the data packets sent to the UE.
  • the UE first submits data received from the radio bearer in the second radio bearer information to the upper layer, and then submits data received from the radio bearer in the third radio bearer information to the upper layer, thereby ensuring that The data packets are submitted in order.
  • step 511 the following steps may be further included:
  • Step 512 The target base station sends a handover completion message to the target core network.
  • the handover completion message is used to notify the target core network that the UE has completed handover between different core networks.
  • the handover completion message may be an existing message type, such as a handover indication, a path switch request, a relocation complete, and the like, or a newly defined message type.
  • Step 513 Information exchange between the target core network and the source core network.
  • the interactive process may use an existing process.
  • Step 514 The source core network sends an end marker packet to the source base station.
  • the end marker packet is used to notify the target cell that the source core network has stopped sending data packets to the source base station (that is, no subsequent data packets are sent to the source base station).
  • the source core network may send one or more end identification packets to the source base station.
  • each PDU session may correspond to an end marker packet, that is, any subsequent data packets without the PDU session are sent to the source base station.
  • each QoS flow corresponds to an end marker packet, that is, subsequent packets without the QoS flow are sent to the source base station.
  • the source core network may carry a GTP-U header indicating that the packet is an end marker packet.
  • step 508 may be performed first, and then step 507 may be performed.
  • steps 510, 511, and 512 that is, step 512, step 510, and step 511 may be performed first, or step 510, step 511, and step 512 may be performed first.
  • step 510 when the target base station transmits data to the terminal, it must be performed after receiving the handover completion message sent by the UE, so as to ensure that the UE can perform data transmission with the target base station.
  • step 514 after the source base station receives the end marker packet sent by the source core network, the source base station sends the end marker packet to the target base station.
  • the source base station sends the end marker packet to the target base station.
  • This embodiment is directed to an application scenario in which the source base station and the target base station are the same base station in the first and second embodiments, that is, the basic steps of this embodiment are basically the same as the methods of the first and second embodiments, that is, the data
  • the methods of sending and the target base station configuring radio bearer information for the UE are the same.
  • the base station can perform data transmission with the source core network and the target core network through two sets of transmission ports, as follows:
  • the base station and the two core networks establish a connection through the data transmission channel, so the base station will submit the data sent to the source core network to the source core network and send it to the target core.
  • the data of the network is submitted to the target core network.
  • a scenario in which a UE switches between the same base station connected to two core networks is mainly used in a load sharing scenario between two core networks, that is, to share the load of each core network.
  • the UE receives no significant changes in the signal quality of the source cell and the target cell in the base station (the source cell and the target cell may be the same cell or different cells), but because the EPC load originally connected by the UE is relatively high, so The network side decided to change the core network connected to the UE to 5GC.
  • the method specifically includes:
  • Step 801 The base station sends a handover request message to the source core network.
  • the handover request message may be an existing message, such as handover requested, and the handover request message may also be another newly defined message, such as a relocation request.
  • the handover request message may carry a request for handover to the target core network, and may also carry a request for the base station to maintain a data transmission channel with the two core networks during the handover process, that is, the UE is connected to the two core networks 5GC and EPC at the same time.
  • the method further includes: the base station configuring first radio bearer information for the UE, where the first radio bearer information is used to establish a radio bearer between the base station and the UE.
  • Step 802 The source core network receives the handover request message and performs an interaction message with the target core network.
  • Step 803 After the target core network performs message interaction with the source core network, it sends a handover request message to the base station.
  • the message carries a notification to the base station that the UE is simultaneously connected to the two core networks 5GC and EPC.
  • Step 804 The base station sends a handover request confirmation message to the target core network.
  • Step 805 The base station receives the handover request confirmation message, and sends a handover notification to the UE.
  • the handover notification message may include at least one of the following:
  • the fourth radio bearer information which is generated by the base station according to the first radio bearer information.
  • the fourth radio bearer information includes: radio bearer configuration information.
  • the radio bearer configuration information includes at least a radio bearer identifier and PDCP layer information corresponding to the source core network configured by the base station for the UE (for example, when the UE switches from 5GC to EPC, At least one of NR (PDCP layer information), RLC layer information configured by the base station for the UE, an instruction to maintain a configuration related to the first radio bearer, and the like.
  • the radio bearer in the fourth radio bearer information is used to bear data in the source core network.
  • For the downlink transmission it is the new data coming down from the source core network and the downlink PDCP SDU that has not been confirmed by the UE to be correctly received before the handover.
  • For the uplink transmission the UE does not receive the uplink PDCP SDU that the base station has acknowledged before the handover.
  • the fifth radio bearer information is the radio bearer information generated by the base station according to the content notified by the target core network.
  • the fifth radio bearer information includes configuration information of the radio bearer.
  • the configuration information of the radio bearer includes at least: a radio bearer identifier and PDCP layer information corresponding to the target core network configured by the base station for the UE (for example, the UE switches from 5GC to At the time of EPC, it is at least one of LTE (PDCP layer information), RLC layer information configured by the base station for the UE, and the like.
  • the radio bearer in the fifth radio bearer information is used to carry a data packet after switching to the target core network. For downlink transmission, it is new data coming down from the target core network, and for uplink transmission, it is new data received by the UE from the application layer.
  • Step 806 The UE sends a handover completion message to the base station. This step is used by the UE to notify the base station that the handover has been completed.
  • Step 807 Data transmission is performed between the base station and the UE, and the data transmission includes uplink data and / or downlink data.
  • downlink data There are two types of downlink data to be sent on the base station side.
  • One is new data from the source core network and / or downlink PDCP SDU that has not been correctly received by the UE before handover is called fourth data.
  • One is from the target core.
  • the new data coming down from the net is called the fifth data.
  • radio bearers configured on the base station side, one is a radio bearer in the fourth radio bearer information for carrying the fourth data; and one is a radio bearer in the fifth radio bearer information for the fifth data.
  • the base station In order to ensure that the UE submits data to the upper layer in the order of the data packets, the base station first sends the fourth data to the UE through the radio bearer in the fourth radio bearer configuration information. After the UE confirms that the data packets have been received correctly, it sends the fifth data. Send to the UE through a radio bearer in the fifth radio bearer configuration information.
  • the process of the base station determining whether the fourth data is correctly received by the UE includes:
  • a possible implementation manner is that the base station determines the reception condition of the UE by using the status information of the RLC layer. Further, after receiving the data packet from the base station, the UE sends RLC status information to the base station, and the RLC status information Indicates the data packet received by the UE; after receiving the status information fed back by the UE, the base station can determine whether the data packet is received correctly according to the indication of the status information. For example, each data packet includes an identifier, which is used to instruct the UE to correctly receive the data packet sent by the base station.
  • the base station judges whether the data packet is correctly received by the UE through the ACK of the MAC layer. Specifically, if the base station receives an ACK from the UE, the UE considers that the UE has correctly received the data packet; otherwise, it considers that the UE has not received the data packet correctly.
  • step 510 the specific method is the same as step 510 in the second embodiment.
  • the UE resends the PDCP SDUs that are not correctly received by the base station to the base station through the radio bearer in the fourth radio bearer information; and sends the newly-upper data packet to the base station through the radio bearer in the fifth radio bearer information.
  • the UE may first transmit the PDCP SDU that was not successfully transmitted in the radio bearer information in the fourth radio bearer information, and confirm that these data packets are correctly received by the base station After that, a new data packet is transmitted on the radio bearer in the fifth radio bearer information.
  • the UE does not successfully transmit the PDCP SDU in the radio bearer information in the fourth radio bearer information, and the UE may send an end packet in the radio bearer in the second radio bearer information, for example, the The end packet is indicated by the SDAP layer or the PDCP layer or the RLC layer. Further, it can be indicated by the bits in the headers of these layers, or by a PDU without a payload in these layers, or by the control of these layers. PDU to indicate.
  • the UE may also transmit a new data packet on the radio bearer in the fifth radio bearer information at the same time, that is, there is no need to confirm whether the data packet transmitted in the radio bearer in the fourth radio bearer information is correctly received by the base station.
  • a new data packet may be transmitted on a radio bearer in the fifth radio bearer information.
  • the base station submits the data packet received from the radio bearer in the fourth radio bearer information to the source core network, and submits the data packet received from the radio bearer in the fifth radio bearer information to the target core network.
  • Process including:
  • the base station may submit the data packets received from the radio bearer in the fifth radio bearer information to the target core network.
  • the base station can simultaneously submit the data packets from the two radio bearers to the two core networks, but after ending the data packets received in the radio bearer in the fourth radio bearer information, the base station sends the data to the source core network.
  • An end marker packet is used to indicate that the transmission of a data packet of a certain E-RAB or a certain PDU session or flow ends.
  • the source core network receives the end identification packet, it notifies the target core network that the data packet corresponding to the E-RAB or PDU session or flow received from the base station can be submitted to other entities (such as the peer communicating with the UE).
  • Step 808 The base station sends a handover completion message to the target core network.
  • This step is the same as step 512 in the second embodiment, which is not repeated in this embodiment.
  • Step 809 The target core network exchanges information with the source core network.
  • This step is the same as step 513 in the second embodiment, which is mainly used for the target core network to notify the source core network that the UE has switched and accessed the target core network.
  • Step 810 The source core network sends an end marker packet to the base station.
  • step 514 is the same as step 514 in the second embodiment, and reference is made to the description of step 514 in the foregoing second embodiment, which is not repeated in this embodiment.
  • the base station establishes a communication connection with the core network EPC and 5GC through a data transmission channel at the same time, and the base station can communicate with the EPC and 5GC through two sets of ports respectively, so that the base station can simultaneously carry the slave two radio bearers simultaneously.
  • the data packets are submitted to the two core networks respectively, which improves the data transmission efficiency.
  • This embodiment is directed to an application scenario in which the source base station and the target base station are the same base station in the first and second embodiments, as shown in FIG. 9, for example. It is the same as the method for configuring radio resource bearer information and transmitting data for the UE in the second embodiment, except that the target base station and the source base station in this embodiment are the same base station, that is, the base station described in this embodiment has a source base station and The function of the target base station.
  • a base station is connected to the source core network and the target core network at the same time.
  • the base station is only connected to the UE.
  • a core network is connected through a data transmission channel.
  • the method includes:
  • Steps 1001 to 1004 are the same as steps 801 to 804 in the third embodiment, and details are not described herein again.
  • Step 1005 The base station receives a handover request confirmation message sent by the target core network, and sends a handover notification to the UE.
  • the handover notification message includes fourth radio bearer information and / or fifth radio bearer information.
  • the content of the fourth radio bearer information and the fifth radio bearer information is the same as the foregoing third embodiment, and reference may be made to the description in the third embodiment, which is not repeated in this embodiment.
  • Step 1006 The UE sends a handover completion message to the base station. This step is used by the UE to notify the base station that the handover has been completed.
  • Step 1007 Data transmission is performed between the base station and the terminal UE, and the data transmission includes uplink data and / or downlink data.
  • the UE resends the PDCP SDUs that are not correctly received by the base station to the base station through the radio bearer in the fourth radio bearer information; and sends the newly-upper data packet to the base station through the radio bearer in the fifth radio bearer information.
  • the UE may first transmit the PDCP SDU that was not successfully transmitted in the radio bearer information in the fourth radio bearer information, and confirm that these data packets are correctly received by the base station. After that, a new data packet is transmitted on the radio bearer in the fifth radio bearer information.
  • the UE does not successfully transmit the PDCP SDU of the radio bearer in the fourth radio bearer information, and at the same time may send an end identifier in the radio bearer in the fourth radio bearer information, for example, the end
  • the identification is indicated by the SDAP layer or the PDCP layer or the RLC layer. Further, it can be indicated by the bits in the header of these layers, or by a PDU without a payload in these layers, or by the control PDUs in these layers. To indicate.
  • the UE may also transmit a new data packet on the radio bearer in the fifth radio bearer information at the same time, that is, after confirming that the data packet transmitted on the radio bearer in the fifth radio bearer information is correctly received by the base station, it may A new data packet is transmitted on the radio bearer in the fifth radio bearer information.
  • the data received by the base station from the radio bearer in the fourth radio bearer information needs special processing.
  • One processing method is the same as the processing method in the second embodiment, and only the second radio bearer information in the second embodiment needs to be replaced with the fourth radio bearer information in this embodiment.
  • Another processing method is that the base station first receives the data in the radio bearer in the fourth radio bearer information, and then submits the data in the radio bearer in the fourth radio bearer information to the source core network, and then sends the fifth The radio bearer data in the radio bearer information is submitted to the target core network. After the base station submits all the radio bearer data in the fourth radio bearer information to the source core network, the base station sends a handover completion message to the target core network. Optionally, after the base station receives the end identifier on the radio bearer in the fourth radio bearer information, the base station submits the data of the radio bearer in the fifth radio bearer information to the target core network.
  • the base station because the base station has only one set of data transmission channels connected to the source core network or the target core network, before the UE switches, the base station performs data transmission with the source core network through the data transmission channel; when the core network switches, the base station The data transmission channel is then used to establish a connection with the target core network and perform data transmission.
  • Step 1008 The base station sends a handover completion message to the target core network.
  • This step is the same as step 512 in the second embodiment, which is not repeated in this embodiment.
  • Step 1009 The target core network exchanges information with the source core network.
  • This step is the same as step 513 in the second embodiment, which is mainly used for the target core network to notify the source core network that the UE has switched and accessed the target core network.
  • Step 1010 The source core network sends an end marker packet to the base station.
  • step 514 is the same as step 514 in the second embodiment, and reference is made to the description of step 514 in the foregoing second embodiment, which is not repeated in this embodiment.
  • the data transmission device is a source base station.
  • the source base station 110 includes a receiving unit 1101, a processing unit 1102, and a sending unit 1103.
  • It may also include other functional modules or units for performing the data transmission methods corresponding to FIG. 3, FIG. 4, FIG. 5, FIG. 8 and FIG.
  • the processing unit 1102 is configured to determine a first data and a wireless air interface protocol sequence number of a data unit used to carry the first data, where the first data includes: the source base station and the terminal during data transmission Data that has not been correctly acknowledged by the terminal.
  • the sending unit 1103 is configured to send the first data and the wireless air interface protocol sequence number to a target base station.
  • the core network to which the target base station is connected is different from the core network to which the source base station is connected.
  • the source base station and the target base station are the source base station and the target base station during the handover process of the different core networks of the terminal.
  • the processing unit 1102 is further configured to determine second data, where the second data includes the terminal in the core network handover process, the source base station from Data received by the source core network to be sent to the terminal.
  • the sending unit 1103 is further configured to send the second data to the target base station, so that the target base station continues to allocate the first data to the second data according to a wireless air interface protocol sequence number corresponding to the first data.
  • the wireless air interface protocol sequence number of the data unit of the two data is further configured to determine second data, where the second data includes the terminal in the core network handover process, the source base station from Data received by the source core network to be sent to the terminal.
  • the sending unit 1103 is further configured to send the second data to the target base station, so that the target base station continues to allocate the first data to the second data according to a wireless air interface protocol sequence number corresponding to the first data.
  • the wireless air interface protocol sequence number of the data unit of the two data is further configured to determine second data, where the second data includes the terminal in the core network handover process,
  • the processing unit 1102 is further configured to: before the source base station sends the first data and the wireless air interface protocol sequence number to the target base station,
  • the terminal is configured with first radio bearer information, and the first radio bearer information is used to establish a radio bearer between the target base station and the terminal.
  • the sending unit 1103 is further configured to send the first radio bearer information to the target base station;
  • the receiving unit 1101 is configured to receive a confirmation message fed back by the target base station, where the confirmation message is used to indicate the target base station and all The second radio bearer information between the terminals is described.
  • the sending unit 1103 is further configured to send the second radio bearer information to the terminal.
  • the confirmation message is further used to indicate third radio bearer information
  • the third radio bearer information is used to configure configuration information of third data, so
  • the third radio bearer information is data received by a target core network of the target base station.
  • the sending unit 1103 is specifically configured to send the first data to the target base station through the first tunnel, where the unacknowledged terminal confirms that the data is received correctly.
  • Data and the wireless air interface protocol serial number are specifically configured to send the first data to the target base station through the first tunnel, where the unacknowledged terminal confirms that the data is received correctly.
  • the first data further includes: an out-of-order data packet received by the source base station from the terminal, and the sending unit 1103 is specifically configured to pass through the second The tunnel sends out of order data packets from the terminal to the target base station and a wireless air interface protocol sequence number corresponding to the out of order data packets.
  • the data transmission device is a target base station, and the target base station 120 includes a receiving unit 1201, a processing unit 1202, and a sending unit 1203. It may also include other functional modules or units for performing the data transmission methods corresponding to FIG. 5, FIG. 8, and FIG. 10.
  • the receiving unit 1201 is configured to receive first data and a wireless air interface protocol sequence number from a source base station, where the first data includes: data that the source base station and the terminal have not correctly received during the data transmission process by the terminal.
  • the wireless air interface protocol sequence number is a sequence number of a data unit determined by the source base station to carry the first data.
  • the sending unit 1203 is configured to send the first data and the wireless air interface protocol sequence number to the terminal.
  • the core network to which the target base station is connected is different from the core network to which the source base station is connected.
  • the source base station and the target base station are the source base station and the target base station during the handover process of the different core networks of the terminal.
  • the receiving unit 1201 is further configured to receive second data from the source base station, where the second data includes the terminal during a core network handover process. Data received by the source base station from the source core network to be sent to the terminal.
  • the processing unit 1202 is configured to continue to allocate the wireless air interface protocol serial number of the data unit of the second data according to the wireless air interface protocol serial number corresponding to the first data to the second data.
  • the sending unit 1203 is further configured to send the second data and a wireless air interface protocol sequence number of the data unit of the second data to the terminal.
  • the receiving unit 1201 is further configured to receive the first radio from the source base station before receiving the first data from the source base station and the wireless air interface protocol sequence number.
  • Bearer information where the first radio bearer information is used to establish a radio bearer between the target base station and the terminal.
  • the processing unit 1202 is further configured to determine second radio bearer information according to the first radio bearer information, and generate a confirmation message, where the confirmation message is used to indicate the second radio bearer between the target base station and the terminal. Carry information.
  • the sending unit 1203 is further configured to send the confirmation message to the source base station.
  • the processing unit 1202 is further configured to determine third radio bearer information according to the first radio bearer information, where the third radio bearer information includes a target base station Configuration information of the connected target core network.
  • the sending unit 1203 is further configured to send the third radio bearer information to the source base station by using the confirmation message.
  • the second radio bearer information includes a first radio bearer, such as a first DRB; and a sending unit 1203 is specifically configured to pass the first radio bearer.
  • the second radio bearer information includes a first radio bearer, such as a first DRB; and a sending unit 1203 is specifically configured to pass the first radio bearer.
  • the processing unit 1202 is further configured to configure a second radio bearer, such as a second DRB, according to the third radio bearer information; the sending unit 1203 further uses Sending third data to the terminal through the second radio bearer, where the third data is data received by a target core network located at the target base station.
  • a second radio bearer such as a second DRB
  • the data transmission device is a terminal.
  • the terminal 130 includes a receiving unit 1301, a processing unit 1302, and a sending unit 1303. It includes other functional modules or units for performing the data transmission methods corresponding to FIG. 5, FIG. 8 and FIG. 10.
  • the receiving unit 1301 is configured to receive first data and a wireless air interface protocol sequence number from the target base station, where the first data includes data that the source base station and the terminal did not confirm that the terminal correctly received during the data transmission process.
  • the wireless air interface protocol sequence number is a sequence number of a data unit determined by the source base station to carry the first data.
  • the processing unit 1302 is configured to sort the first data and the data buffered in the terminal according to the wireless air interface protocol serial number.
  • the core network to which the target base station is connected is different from the core network to which the source base station is connected.
  • the source base station and the target base station are the source base station and the target base station during the handover process of the different core networks of the terminal.
  • the receiving unit 1301 is further configured to receive the second data and the wireless air interface protocol sequence number of the data unit of the second data from the target base station.
  • the second data includes data that the source base station receives from the source core network to be sent to the terminal during the core network handover process;
  • the processing unit 1302 is further configured to perform the operations according to the second data and the first data.
  • the wireless air interface protocol sequence number of the two-data data unit sorts the second data.
  • the receiving unit 1301 is further configured to receive third data from the target base station and a wireless air interface protocol sequence number of the data unit of the third data
  • the third data is data received from a target core network of the target base station;
  • the processing unit 1302 is further configured to sort the third data according to a wireless air interface protocol sequence of the data unit of the third data .
  • the receiving unit 1301 is further configured to receive the data from the source before the terminal receives the first data from the target base station and the wireless air interface protocol sequence number.
  • a handover notification message of a base station where the handover notification may be an RRC reconfiguration message, and the handover notification message includes a target cell ID accessed to the target base station.
  • the processing unit 1302 is further configured to access the target cell according to the target cell ID, and send a handover completion message to the target base station.
  • the handover notification message further includes second radio bearer information, where the second radio bearer information includes a first radio bearer; for example, the first A DRB for transmitting first data with an SN number that has not been acknowledged by the UE.
  • the receiving unit 1301 is specifically configured to receive the first data and the data unit of the first data by using the first radio bearer, and the wireless air interface protocol sequence number.
  • the handover notification message further includes third radio bearer information, where the third radio bearer information includes a second radio bearer; the second DRB is used to transmit the switched data packet, that is, the third data.
  • the receiving unit 1301 is specifically configured to use the second radio bearer to receive the third data and a wireless air interface protocol sequence number of a data unit of the third data.
  • the present application further provides a network device, which may be a base station, a terminal, or a core network device in the foregoing embodiments.
  • the base station may be an LTE eNB connected to a core network EPC, or an eLTE eNB connected to a 5GC core network, or may be another source base station or a target base station.
  • the network device includes a transceiver 141, a processor 142, and a memory 143.
  • the network device may further include more or fewer components, or a combination of certain components, or a different component arrangement. This application does not limit this.
  • the transceiver 141 is used for receiving and sending data or messages, and performs data transmission with other nodes / devices in the network.
  • the transceiver 141 may include a transceiver module, and the transceiver module may include communication modules such as a wireless local area network (WLAN) module, a Bluetooth module, and a baseband module, and a radio frequency corresponding to the communication module ( radio frequency (RF) circuit for wireless local area network communication, Bluetooth communication, infrared communication and / or cellular communication system communication, such as wideband code division multiple access (WCDMA) and / or high-speed downlink Packet access (high speed, downlink, packet access, HSDPA).
  • the transceiver module is used to control the communication of various components in the network equipment, and can support direct memory access.
  • the processor 142 is a control center of a network device, and connects various parts of the entire network device by using various interfaces and lines, and runs or executes software programs and / or modules stored in the memory 143 and calls data stored in the memory 143 To perform various functions of the network device and / or process data.
  • the processor 142 may be composed of an integrated circuit (IC), for example, may be composed of a single packaged IC, or may be composed of a plurality of packaged ICs connected to the same function or different functions.
  • the processor may include only a central processing unit (CPU), or a GPU, a digital signal processor (DSP), and a control chip (such as a baseband chip) in the transceiver. combination.
  • the CPU may be a single operation core, or may include a multiple operation core.
  • the memory 143 may include volatile memory (for example, Random Access Memory, RAM); and may also include non-volatile memory (for example, Flash memory), A hard disk (Hard, Sisk, Drive, HDD) or a solid state drive (Solid-State, Drive (SSD); the storage may also include a combination of the above types of storage.
  • volatile memory for example, Random Access Memory, RAM
  • non-volatile memory for example, Flash memory
  • a hard disk Hard, Sisk, Drive, HDD
  • SSD solid state drive
  • a program or code may be stored in the memory, and the processor may implement a function of the network device by executing the program or code.
  • the functions to be implemented by the transceiver 141 may be implemented by the receiving unit and the sending unit in the foregoing various device embodiments, or may be implemented by the transceiver 141 controlled by the processor 142; the functions to be implemented by each processing unit are It may be implemented by the processor 142.
  • the present application also provides a computer storage medium, where the computer storage medium may store a program, and when the program is executed, may include part or all of the steps in the embodiments of the device upgrade method provided by the application.
  • the storage medium may be a magnetic disk, an optical disk, a read-only memory ROM or a random access memory RAM.
  • all or part of them may be implemented by software, hardware, firmware, or any combination thereof.
  • software When implemented in software, it may be implemented in whole or in part in the form of a computer program product.
  • the computer program product includes one or more computer instructions, such as a switching instruction.
  • a switching instruction When the computer loads and executes the computer program, all or part of the processes or functions according to the foregoing embodiments of the present application are generated.
  • the computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device.
  • the computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium.
  • the computer instructions may be from a network node, computer, server, or data center. Transmission to another site, computer, or server by wire or wireless.
  • the computer-readable storage medium may be any available medium that can be accessed by a computer or a storage device such as a server, a data center, and the like that includes one or more available medium integration.
  • the usable medium may be a magnetic medium, such as a floppy disk, a hard disk, a magnetic tape, an optical medium (such as a DVD), or a semiconductor medium, such as a solid state drive SSD, or the like.
  • the base station described in the embodiments of the present application may be a base station (Base Transceiver Station, BTS) in GSM or CDMA, or a base station (NodeB) in WCDMA, or an evolutionary base station (LTE) in LTE , ENB / e-NodeB), or ng-eNB, or gNB, this application is not limited.
  • BTS Base Transceiver Station
  • NodeB base station
  • LTE evolutionary base station
  • ng-eNB ng-eNB
  • the terminal described in the embodiments of the present application may be a device that provides voice and / or data connectivity to a user, a handheld device with a wireless connection function, or another processing device connected to a wireless modem, such as a wireless terminal.
  • the wireless terminal may communicate with one or more nodes via a radio access network RAN, and the wireless terminal may be a mobile terminal, such as a mobile phone (or a "cellular" phone) and a computer with a mobile terminal, for example, It can be a portable, pocket, handheld, computer-built or vehicle-mounted mobile device that exchanges language and / or data with the wireless access network.
  • a mobile terminal such as a mobile phone (or a "cellular" phone) and a computer with a mobile terminal, for example, It can be a portable, pocket, handheld, computer-built or vehicle-mounted mobile device that exchanges language and / or data with the wireless access network.
  • PCS Personal Communication service
  • SIP session initiation protocol
  • WLL wireless local loop
  • PDA Personal Digital Assistant
  • a wireless terminal can also be referred to as a system, a subscriber unit, a subscriber station, a mobile station, a mobile station, a remote station, an access point, and an access point.
  • Remote terminal Remote Terminal
  • Access terminal Access terminal
  • user terminal User terminal
  • user agent User Agent
  • User Equipment User Equipment
  • the technology in the embodiments of the present application can be implemented by means of software plus a necessary universal hardware platform. Based on such an understanding, the technical solutions in the embodiments of the present application can be embodied in the form of software products that are essentially or contribute to the existing technology.
  • the computer software product can be stored in a storage medium, such as ROM / RAM. , Magnetic disks, optical disks, etc., including a number of instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to perform the methods described in various embodiments of the present invention or certain parts of the embodiments.

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Abstract

公开了一种数据传输方法和装置，所述方法包括：源基站确定第一数据和用于承载所述第一数据的数据单元的无线空口协议序列号，第一数据包括：所述源基站与终端在数据传输过程中未被终端确认正确接收的数据；所述源基站向目标基站发送所述第一数据和所述无线空口协议序列号；其中，所述目标基站所连接的核心网与所述源基站所连接的核心网不同。本方法中，源基站向目标基站发送的第一数据和第一数据的数据单元中携带无线空口序列号，由于这些无线空口序列号与终端之前正确接收的数据包是按照同一规则顺序排序，使得目标基站将这些数据转发给终端后，终端能够对接收到的数据包正确排序，进而保证所有接收的数据包按序提交给上层。

Description

一种数据传输方法和装置
本申请要求于2018年8月28日提交中国专利局、申请号为201810989663.9、发明名称为“一种数据传输方法和装置”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，尤其涉及一种数据传输方法和装置。
背景技术
随着通信技术的发展，越来越多的终端需要接入到无线网络，且越来越多的业务需要高速率的保证。这些对网络提出了更高吞吐量的需求，为了满足这种需求，标准中正在研究新一代的无线通信系统，可以称为5G通信系统。无线通信系统由网络侧设备和终端组成。网络设备由基站和核心网组成，终端通过与网络侧进行交互完成无线通信的任务。
在4G通信系统中，基站和终端之间的无线通信技术称为长期演进(Long Term Evolution，LTE)，对应的基站称为LTE演进型基站(evolved NodeB，eNB)，核心网称为演进型分组核心网(evolved packet core,EPC)。在5G通信系统中，基站和终端之间的无线通信技术称为新空口(new radio，NR)，对应的基站称为gNB，核心网称为5GC(5generation core)。为了使得基站和核心网可以独立的演进，无线通信标准中允许eNB连接到4G的核心网EPC(即终端通过LTE eNB连接到EPC),也允许eNB连接到5G系统中的核心网5GC，对应的基站可以称为演进型长期演进(evolved LTE,eLTE)eNB,也称为ng-eNB。另外，也允许eLTE eNB同时连接到EPC和5GC，或者还可以一个小区同时连接到EPC和5GC。
当终端通过LTE eNB基站连接到EPC时，基站与终端的通信数据可以采用LTE的各层无线协议处理，例如LTE包数据汇聚协议(Packet Data Convergence Protocol，PDCP)/LTE无线链路控制(Radio Link Control，RLC)/LTE介质访问控制(Medium Access Control，MAC)/LTE物理层(Physical,PHY)；当终端通过基站gNB连接到5GC时，基站与终端的通信数据可以采用NR的各层无线协议标准，例如NR服务数据适配协议(Service Data Adaptation Protocol,SDAP)/NR PDCP/NR RLC/NR MAC/NR PHY。当终端通过基站ng-eNB连接到5GC时，基站与终端的通信数据可以综合采用NR/LTE的各层无线协议标准，例如NR SDAP/NR PDCP/LTE RLC/LTE MAC/LTE PHY。当终端与基站通信时，某些业务对数据包有按序提交的要求(即数据包要按照先后关系发送给对端。比如基站从终端接收数据时，基站收到数据时必须按照一定的先后关系提交给核心网)，基站与终端之间的通信中，发送端一般会为数据包在某些无线协议上分配一个序列号，这样接收端就可以根据该序列号的先后关系来判断该数据包是否乱序了。
运营商可能在一部分区域中布局LTE基站，在另外一部分区域布局eLTE基站,这样终端从LTE eNB移动到eLTE eNB时需要进行对应的核心网切换。也可能在基站同时连接到EPC和5GC的场景中，考虑到核心网的负荷均衡，需要把一部分终端在EPC和5GC之间进 行切换。也可能终端从LTE eNB移动到gNB时需要对应的切换。由于当终端连接到不同的核心网时，基站和终端之间的无线承载采用不同的协议，可能会导致数据丢失和错序提交。
例如，当通过LTE基站连接EPC的终端切换到与连接到5GC的NR基站过程中，对于下行数据：对于未被终端正确接收的下行数据，源小区会将其转移到源核心网，源核心网再把该下行数据经过目标核心网和目标小区传输给该终端，目标小区重新为这些下行数据分配序列号。终端的无线协议层在切换过程中会把从源小区中收到的数据提交给上层，再在目标小区接收数据。由于未被正确接收的数据可能只是一些数据包中某些数据包未被终端接收，比如从源核心网来的数据包顺序为数据包1、2、3、4、5，数据包1、3、5被终端正确接收，数据包2、4没有被终端正确接收，则终端的无线协议层在切换过程中会把数据包1、3、5提交给上层，之后再把从目标小区收到数据包2、4提交给上层，这样就导致了上层收到数据包1、2、3、4、5是乱序的。
发明内容
本申请提供了一种数据传输方法和装置，以保证终端与基站间通信过程中数据不丢包且能够按序提交。
第一方面，本申请提供了一种数据传输方法，所述方法包括：源基站确定第一数据和用于承载所述第一数据的数据单元的无线空口协议序列号，例如SN号，所述第一数据包括：所述源基站与终端在数据传输过程中未被终端确认正确接收的数据；所述源基站向目标基站发送所述第一数据和所述无线空口协议序列号；其中，所述目标基站所连接的核心网与所述源基站所连接的核心网不同，所述源基站和所述目标基站为所述终端在不同核心网切换过程中的源基站和目标基站。
本方法中，源基站向目标基站发送在源基站与终端在数据传输过程中未被终端确认正确接收的数据，且这些数据所对应的数据单元中携带无线空口序列号，使得目标基站接收到携带有原来无线空口序列号的数据包后，将这些序列号以及数据包发送给终端，由于这些无线空口序列号与终端之前正确接收的数据包是按照同一规则顺序排序，所以终端能够对接收到的数据包正确排序，进而保证所有接收的数据包按序提交给上层。
可选的，结合第一方面，在第一方面的一种可能的实现方式中，所述方法还包括：源基站确定第二数据，所述第二数据包括：所述终端在核心网切换过程中，所述源基站从源核心网接收的待发送给所述终端的数据；源基站向所述目标基站发送所述第二数据，以使所述目标基站对所述第二数据按照所述第一数据对应的无线空口协议序列号，继续分配所述第二数据的数据单元的无线空口协议序列号。
本实现方式中，终端在核心网切换过程中，源基站将产生的第二数据和第二数据对应的无线空口协议序列号发送给目标基站，由于该第二数据对应的无线空口协议序列号是在第一数据的基础上，继续配置的，所以接收端的目标基站和终端能够识别并正确地排序，进而保证接收的数据包按序提交。
可选的，结合第一方面，在第一方面的另一种可能的实现方式中，在所述源基站向目标基站发送所述第一数据和所述无线空口协议序列号之前，所述方法还包括：源基站为所述终端配置第一无线承载信息，所述第一无线承载信息用于建立所述源基站和所述终端之间的无线承载；所述源基站向所述目标基站发送所述第一无线承载信息；所述源基站接收所述目标基站反馈的确认消息，所述确认消息用于指示所述目标基站和所述终端之间的第 二无线承载信息；所述源基站向所述终端发送所述第二无线承载信息。
其中，所述第一无线承载信息包括无线承载配置，进一步地，所述无线承载配置中包括：DRB标识、该DRB对应的NR PDCP配置信息和NR SDAP配置信息。进一步地，所述NR SDAP配置信息中包括：源基站为UE配置的DRB与QoS flow之间的映射关系，另外，所述NR SDAP配置信息中还包括以下至少任意一项：DRB承载的PDU session ID，SDAP上下行分别是否配置SDAP报文头，及该DRB是否为默认DRB。此外，所述无线承载配置中还可以包括：源基站为UE配置的DRB配置。所述DRB配置具体包括：DRB标识、该DRB对应的源基站为UE配置的PDCP信息等。
可选的，结合第一方面，在第一方面的又一种可能的实现方式中，所述确认消息还用于指示第三无线承载信息，所述第三无线承载信息为用于配置第三数据的配置信息，所述第三数据为从所述目标基站的目标核心网所接收的数据。
本方面中，通过反馈第三无线承载信息，使得目标基站能够根据该第三无线承载信息确定用于承载目标核心网下发的数据，并且按照目标核心网的协议规则对新下发的数据进行序列号的排序，从而避免与第一数据和第二数据产生混乱，进一步保证目标基站对来自源基站和来自目标核心网的不同数据的有序接收和处理。
可选的，结合第一方面，在第一方面的又一种可能的实现方式中，所述源基站向目标基站发送所述第一数据和所述无线空口协议序列号，包括：源基站通过第一隧道向所述目标基站发送所述第一数据中的所述未被终端确认正确接收的数据以及所述无线空口协议序列号。
可选的，结合第一方面，在第一方面的又一种可能的实现方式中，所述第一数据还包括：所述源基站从终端接收的乱序的数据包，所述源基站向目标基站发送所述第一数据和所述无线空口协议序列号，包括：源基站通过第二隧道向所述目标基站发送所述第一数据中的来自所述终端的乱序的数据包以及与所述乱序的数据包对应的无线空口协议序列号。
本实现方式中，对于上行数据，终端向在目标小区或目标基站发送上行乱序的数据包和对应的序列号，从而避免数据包一些发送了但未被源基站或源小区接收的数据包丢失。
第二方面，本申请还提供了一种数据传输方法，所述方法包括：目标基站接收来自源基站的第一数据和无线空口协议序列号，所述第一数据包括：所述源基站与终端在数据传输过程中未被终端确认正确接收的数据，所述无线空口协议序列号为所述源基站确定的用于承载所述第一数据的数据单元的序列号；目标基站向所述终端发送所述第一数据和所述无线空口协议序列号；其中，所述目标基站所连接的核心网与所述源基站所连接的核心网不同，所述源基站和所述目标基站为所述终端在不同核心网切换过程中的源基站和目标基站。
可选的，结合第二方面，在第二方面的一种可能的实现方式中，所述方法还包括：目标基站接收来自所述源基站的第二数据，所述第二数据包括所述终端在核心网切换过程中，所述源基站从源核心网接收的待发送给所述终端的数据；目标基站对所述第二数据按照所述第一数据对应的无线空口协议序列号，继续分配所述第二数据的数据单元的无线空口协议序列号；所述目标基站向所述终端发送所述第二数据和所述第二数据的数据单元的无线空口协议序列号。
可选的，结合第二方面，在第二方面的又一种可能的实现方式中，所述目标基站接收 来自源基站的第一数据和无线空口协议序列号之前，所述方法还包括：目标基站接收来自源基站的第一无线承载信息，所述第一无线承载信息用于建立所述目标基站和所述终端之间的无线承载；目标基站根据所述第一无线承载信息确定第二无线承载信息，以及生成确认消息，所述确认消息用于指示所述目标基站和所述终端之间的所述第二无线承载信息；目标基站向所述源基站发送所述确认消息。
可选的，结合第二方面，在第二方面的又一种可能的实现方式中，所述方法还包括：目标基站根据所述第一无线承载信息确定第三无线承载信息，所述第三无线承载信息包括目标基站所连接的目标核心网的配置信息；目标基站通过所述确认消息携带向所述源基站发送所述第三无线承载信息。
可选的，结合第二方面，在第二方面的又一种可能的实现方式中，所述第二无线承载信息中包括第一无线承载；目标基站向所述终端发送所述第一数据和所述无线空口协议序列号，包括：目标基站通过所述第一无线承载向所述终端发送所述第二数据和所述第二数据的数据单元的无线空口协议序列号。
可选的，结合第二方面，在第二方面的又一种可能的实现方式中，所述第二无线承载信息中包括第一无线承载；所述目标基站向所述终端发送所述第二数据和所述第二数据的数据单元的无线空口协议序列号，包括：目标基站通过所述第一无线承载向所述终端发送所述第二数据和所述第二数据的数据单元的无线空口协议序列号。
可选的，结合第二方面，在第二方面的又一种可能的实现方式中，所述方法还包括：所述目标基站根据所述第三无线承载信息配置第二无线承载；目标基站将第三数据通过所述第二无线承载发送给所述终端，所述第三数据为位于所述目标基站的目标核心网所接收的数据。
可选的，结合第二方面，在第二方面的又一种可能的实现方式中，所述方法还包括：目标基站向所述源基站发送切换完成消息，所述切换完成消息中包括结束标识，所述结束标识用于指示所述源核心网停止向所述源基站发送数据。
第三方面，本申请还提供了一种数据传输方法，应用于终端，所述方法包括：终端接收来自目标基站的第一数据和无线空口协议序列号，所述第一数据包括：源基站与终端在数据传输过程中未被所述终端确认正确接收的数据，所述无线空口协议序列号为所述源基站确定的用于承载所述第一数据的数据单元的序列号；终端根据所述无线空口协议序列号对所述第一数据和缓存在终端的数据进行排序。
其中，所述目标基站所连接的核心网与所述源基站所连接的核心网不同，所述源基站和所述目标基站为所述终端在不同核心网切换过程中的源基站和目标基站。
本方面中，终端在接收到来自目标核心网的第一数据后，由于该第一数据中包括第一数据的数据单元的序列号，例如SN号，所以终端可以根据该序列号对接收的第一数据和之前成功接收的数据进行排序，进而保证所有数据包按照一定的顺序排序，最后将排序号的数据包传输给上层。
可选的，结合第三方面，在第三方面的一种可能的实现方式中，所述方法还包括：终端接收来自所述目标基站的第二数据和第二数据的数据单元的无线空口协议序列号，所述第二数据包括：所述终端在核心网切换过程中，所述源基站从源核心网接收的待发送给所述终端的数据；所述终端按照所述第二数据的数据单元的无线空口协议序列号对所述第二 数据进行排序。
可选的，结合第三方面，在第三方面的另一种可能的实现方式中，所述方法还包括：所述终端接收来自所述目标基站的第三数据和所述第三数据的数据单元的无线空口协议序列号，所述第三数据为从所述目标基站的目标核心网所接收的数据；终端按照所述第三数据的数据单元的无线空口协议序列号对所述第三数据进行排序。
可选的，结合第三方面，在第三方面的又一种可能的实现方式中，在所述终端接收来自目标基站的第一数据和无线空口协议序列号之前，所述方法还包括：所述终端接收来自所述源基站的切换通知消息，所述切换通知消息中包括接入到所述目标基站的目标小区ID；所述终端根据所述目标小区ID接入到所述目标小区，并向所述目标基站发送切换完成消息。
其中，所述切换通知消息可以是RRC重配消息。
可选的，结合第三方面，在第三方面的又一种可能的实现方式中，所述切换通知消息中还包括第二无线承载信息，其中，所述第二无线承载信息中包括第一无线承载；第一无线承载DRB用于传输带有SN号的未被UE确认的第一数据，所述终端接收来自目标基站的第一数据和无线空口协议序列号，包括；终端利用所述第一无线承载接收所述第一数据和第一数据的数据单元的所述无线空口协议序列号。
可选的，结合第三方面，在第三方面的又一种可能的实现方式中，所述切换通知消息中还包括第三无线承载信息，其中，所述第三无线承载信息中包括第二无线承载；第二无线承载DRB用于传输切换到目标核心网的数据包，即第三数据，所述终端接收来自所述目标基站的第三数据，包括：终端利用所述第二无线承载接收所述第三数据和第三数据的数据单元的无线空口协议序列号。
第四方面，本申请还提供了一种数据传输装置，所述装置可以是源基站，其中，所述装置中包括用于执行上述第一方面以及第一方面的各种实现方式中方法步骤的单元。
具体地，所述装置包括接收单元、处理单元和发送单元，此外，还可以还包括存储单元等其他单元或模块等。
第五方面，本申请还提供了一种数据传输装置，所述装置可以是目标基站，其中，所述装置中包括用于执行上述第二方面以及第二方面的各种实现方式中方法步骤的单元。
具体地，所述装置包括接收单元、处理单元和发送单元，此外，还可以还包括存储单元等其他单元或模块等。
第六方面，本申请还提供了一种数据传输装置，所述装置可以是终端，其中，所述装置中包括用于执行上述第三方面以及第三方面的各种实现方式中方法步骤的单元。
具体地，所述装置包括接收单元、处理单元和发送单元，此外，还可以还包括存储单元等其他单元或模块等。
第七方面，在具体的硬件实现层面，本申请还提供了一种网络设备，所述网络设备包括处理器、收发器和存储器，该网络设备可以一种数据传输装置，例如可以是源基站、目标基站、源核心网、目标核心网或者终端。
可选的，在所述网络设备为源基站的情况下，所述处理器，用于确定第一数据和用于承载所述第一数据的数据单元的无线空口协议序列号，所述第一数据包括：所述源基站与终端在数据传输过程中未被终端确认正确接收的数据；所述收发器，用于向目标基站发送 所述第一数据和所述无线空口协议序列号；其中，所述目标基站所连接的核心网与所述源基站所连接的核心网不同，所述源基站和所述目标基站为所述终端在不同核心网切换过程中的源基站和目标基站。
此外，所述处理器和收发器还用于实现前述第一方面中的其它各种实现的功能。
可选的，在所述网络设备为目标基站的情况下，所述收发器，用于接收来自源基站的第一数据和无线空口协议序列号，所述第一数据包括：所述源基站与终端在数据传输过程中未被终端确认正确接收的数据，所述无线空口协议序列号为所述源基站确定的用于承载所述第一数据的数据单元的序列号；以及，向所述终端发送所述第一数据和所述无线空口协议序列号；其中，所述目标基站所连接的核心网与所述源基站所连接的核心网不同，所述源基站和所述目标基站为所述终端在不同核心网切换过程中的源基站和目标基站。
此外，所述处理器和收发器还用于实现前述第二方面中的其它各种实现的功能。
可选的，在所述网络设备为终端的情况下，所述收发器，用于接收来自目标基站的第一数据和无线空口协议序列号，所述第一数据包括：源基站与终端在数据传输过程中未被所述终端确认正确接收的数据，所述无线空口协议序列号为所述源基站确定的用于承载所述第一数据的数据单元的序列号；所述处理器，用于根据所述无线空口协议序列号对所述第一数据和缓存在终端的数据进行排序；其中，所述目标基站所连接的核心网与所述源基站所连接的核心网不同，所述源基站和所述目标基站为所述终端在不同核心网切换过程中的源基站和目标基站。
此外，所述处理器和收发器还用于实现前述第三方面中的其它各种实现的功能。
第八方面，本申请还提供了一种计算机存储介质，该计算机存储介质可存储有程序，该程序执行时可实现上述各个方面中，包括本申请提供的数据传输方法各实施例中的部分或全部步骤。
第九方面，本申请还提供了一种计算机程序产品，所述计算机程序产品包括一个或多个计算机指令，例如设备升级指令。在计算机加载和执行所述计算机程序时，可实现包括本申请提供的数据传输方法各实施例中的部分或全部步骤。
第十方面，本申请还提供了一种数据传输系统，所述系统中包括：源基站、源核心网、目标基站、目标核心网和终端等，其中，所述源基站可以是上述第四方面及第四方面各种实现方式中的数据传输装置，所述目标基站可以是上述第五方面以及第五方面各种实现方式中的数据传输装置，所述终端可以是上述第六方面以及第六方面各种实现方式中的数据传输装置，所述源核心网可以是EPC，所述目标核心网可以是5GC；或者所述源核心网是5GC，所述目标核心网是EPC。
第十一方面，本申请还提供了另一种数据传输系统，所述系统中包括：基站、源核心网、目标核心网和终端等，其中，该基站同时与源核心网和目标核心网相连接，位于源核心网和目标核心网覆盖的区域内，该基站具有前述方面中的源基站和目标基站的功能。
其中，所述基站具有两套传输端口，分别与源核心网和目标核心网进行数据传输。
可选的，对于下行传输，所述方法包括：在基站与终端UE进行数据传输的过程中，基站先通过第四无线承载信息中的无线承载来向UE传输核心网切换之前未被UE确认正确接收的下行PDCP SDU，例如第四数据，和该第四数据对应的序列号；然后基站再通过第五无线承载信息中的无线承载向UE传送从目标核心网下来的新数据，例如第五数据，和该 第五数据对应的序列号。
可选的，对于上行传输，所述方法包括：UE通过第四无线承载信息中的无线承载向基站重新发送那些没有被基站确认正确接收的PDCP SDU；并且通过第五无线承载信息中的无线承载向基站发送上层新下来的数据包。
可选的，结合第十一方面，在第十一方面的一种可能的实现方式中，方法包括：UE先在第四无线承载信息中的无线承载传输未成功发送的PDCP SDU，当确认所述PDCP SDU被基站正确接收之后，再在第五无线承载信息中的无线承载上传输新的数据包。
可选的，结合第十一方面，在第十一方面的另一种可能的实现方式中，方法包括：UE在第四无线承载信息中的无线承载传输未成功发送的PDCP SDU，同时在第五无线承载信息中的无线承载上传输新的数据包。
其中，所述基站通过第一数据传输通道与源核心网建立通信连接；通过第二数据传输通道与目标核心网建立通信连接。
可选的，结合第十一方面，在第十一方面的另一种可能的实现方式中，所述方法包括：基站先接收第四无线承载信息中的无线承载中的数据，然后将所述第四无线承载信息中的无线承载的数据发送给源核心网，然后再将第五无线承载信息中的无线承载的数据发送给目标核心网，待数据发送完成之后，所述基站再向目标核心网发送切换完成消息。
其中，所述基站通过第三数据传输通道与源核心网建立通信连接；或者，当切换核心网后，所述基站通过第四数据传输通道与目标核心网建立通信连接，且所述基站与源核心网之间的第三数据传输通道端口。
本实施例提供的方法，目标基站通过源基站的第一无线承载信息为UE配置第二无线承载信息，所述第二无线承载信息中的DRB用于从源基站转移过来的第一数据和/或第二数据，且这些数据保留源基站分配的无线空口序列号，所以接收端目标基站可以通过该DRB向UE发送这些数据包，从而保证数据包不丢失，且UE可以按照该序列号的顺序对切换核心网前后获取的所有数据包进行排序，进而保证了所有数据包能够按序提交给上层。
此外，目标基站还通过建立第三无线承载信息，该第三无线承载信息中的无线承载用于承载切换至目标核心网的数据，从而目标核心网的数据可以在目标基站上以新的无线承载传输，避免与源核心网中的数据包产生乱序，进一步地保证发送给UE的数据包的有序性。
附图说明
图1a为本申请实施例提供的一种UE在不同核心网切换的场景示意图；
图1b为本申请实施例提供的另一种UE在不同核心网切换的场景示意图；
图2a为本申请实施例提供的一种LTE eNB连接到EPC时用户面协议栈的示意图；
图2b为本申请实施例提供的一种LTE eNB连接到EPC时控制面协议栈的示意图；
图2c为本申请实施例提供的一种eLTE eNB连接到5GC时用户面协议栈的示意图；
图3为本申请实施例提供的一种数据传输方法的流程图；
图4为本申请实施例提供的另一种数据传输方法的流程图；
图5为本申请实施例提供的一种数据传输方法的信令流程图；
图6a为本申请实施例提供的一种UE侧协议栈从EPC切换到5GC时的示意图；
图6b为本申请实施例提供的一种UE侧协议栈从5GC切换到EPC时的示意图；
图7为本申请实施例提供的一种数据传输的示意图；
图8为本申请实施例提供的另一种数据传输方法的信令流程图；
图9为本申请实施例提供的一种两个核心网同时连接一个基站的场景示意图；
图10为本申请实施例提供的又一种数据传输方法的信令流程图；
图11为本申请实施例提供的一种源基站的结构示意图；
图12为本申请实施例提供的一种目标基站的结构示意图；
图13为本申请实施例提供的一种终端的结构示意图；
图14为本申请实施例提供的一种网络设备的结构示意图。
具体实施方式
为了使本技术领域的人员更好地理解本申请实施例中的技术方案，并使本申请实施例的上述目的、特征和优点能够更加明显易懂，下面结合附图对本申请实施例中的技术方案作进一步详细的说明。
在对本申请实施例的技术方案说明之前，首先对本申请实施例中的应用场景和相关技术术语进行解释和说明。
本申请的技术方案可应用于终端在不同核心网切换的技术场景。如图1a所示，该场景中不同的核心网包括：4G的核心网EPC和5G的核心网5GC，其中，EPC用于为终端，例如用户设备(User Equipment，UE)提供4G核心网的功能，5GC用于为终端提供5G核心网的功能。另外，还包括：与EPC相连接的LTE基站(LTE eNB)以及与5GC相连接的LTE基站(eLTE eNB),或者与EPC相连接的LTE基站(LTE eNB)以及与5GC相连接的NR基站gNB，其中，所述LTE eNB用于为终端提供无线接入服务；所述eLTE eNB用于为终端提供无线接入服务；所述gNB用于为终端提供无线接入服务。
UE在连接到两个核心网的不同基站之间切换的场景：主要用于UE从一个基站的覆盖区移动到另外一个基站的覆盖区(比如发现另外一个基站的信号质量更好)。比如UE从基站1的覆盖区域移动到了基站2的覆盖区域，这样由于基站2的无线质量更好，所以网络侧决定将UE切换到基站2，但由于基站2只连接到了5GC，所以需要UE切换核心网。
当终端通过LTE eNB连接EPC时，LTE eNB与终端的无线承载(radio bearer，RB)采用LTE PDCP/LTE RLC/LTE MAC/LTE PHY协议。当终端通过eLTE eNB连接到5GC时，eLTE eNB与终端的无线承载采用NR SDAP/NR PDCP/LTE RLC/LTE MAC/LTE PHY协议。
具体地，下面介绍基站与不同核心网连接时用户面或控制面协议栈结构的示意图，以及每层协议栈的功能。
如图2a所示，为LTE eNB连接到EPC时用户面协议栈的示意图。其中，对于用户面而言，在UE和LTE eNB的协议栈中协议层按照从上到下分别为：包数据汇聚协议(Packet Data Convergence Protocol，PDCP)层、无线链路控制(Radio Link Control，RLC)层、介质访问控制(Medium Access Control，MAC)层和物理层(Physical，PHY)。
其中，PDCP层，可用于执行诸如安全性、头压缩、加密之类的服务。该PDCP层可以存在于多个PDCP实体，每个PDCP实体承载一个RB的数据。所述PDCP层还用于配置并保证向上提交的数据是有序的(即按序提交数据)。
RLC层，用于执行诸如分段、重新装配、重传等服务。所述RLC层可以存在于多个RLC实体，每个RLC实体可以为每个PDCP实体提供服务。
MAC层，用于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ARQ(HARQ)的确认和否定服务。
PHY层，用于接收来自MAC层的数据，并对该数据进行编码和传输。
如图2b所示，示出了一种LTE eNB连接到EPC时控制面协议栈的示意图。对于控制面而言，UE和LTE eNB的协议栈中协议层由上至下分别为：非接入(Non-Access Stratum，NAS)层、无线资源控制(Radio Resource Control，RRC)层、PDCP层、RLC层、MAC层和PHY层。
其中，RRC层，用于执行消息广播、寻呼、RRC链接建立、无线承载控制、移动、UE测量上报控制等功能。
NAS层，用于执行鉴权、移动性管理、安全控制等功能。
每一层处理完数据之后的数据，在本层称为协议数据单元(Protocol Data Unit，PDU)。对于每一层而言，从上一层输入的数据成为本层的服务数据单元(Service Data Unit，SDU)。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。
如图2c所示，示出了一种eLTE eNB连接到5GC时用户面协议栈的示意图。与连接到EPC的用户面协议栈不同的是，在UE和eLTE eNB的协议栈中新增加了服务数据适配协议(Service Data Adaptation Protocol，SDAP)层。
所述SDAP层，用于将来自5GC的各个服务质量流(QoS flow)映射到无线接入层的无线数据承载(Data Radio Bearer，DRB)，即根据QoS flow对应的业务属性，把QoS flow对应的数据包放在对应的DRB上传输。此外SDAP层还可负责为上下行数据包增加QoS flow标识。
其中，UE和基站之间通过RB来传输。所述RB分为信令无线承载(Signalling Radio Bearer，SRB)和数据无线承载(Data Radio Bearer，DRB)。其中，SRB可用于传输RRC消息以及NAS消息；DRB可用于传输业务数据。另外，每个RB可对应一个逻辑信道,也可以认为每个RLC实体对应一个逻辑信道。
当LTE基站连接到EPC时，EPC与LTE基站之间可以按照演进全球陆地无线接入无线接入承载(Evolved Universal Terrestrial Radio Access-Radio Access Bearer，E-RAB)粒度建立GPRS隧道协议(GPRS Tunnelling protocol，GTP)数据隧道，上下行数据传输都是按照E-RAB粒度的GTP隧道进行传输。EPC在为UE建立业务时，会在核心网和基站间为对应的E-RAB分配一个GTP数据隧道，该GTP数据隧道通过传输层地址和隧道末端标识(Tunnel Endpoint Identifier，GTP-TEID)来标识，用于传输对应的业务数据，且上下行的数据隧道可以分开。
LTE基站与UE之间按照E-RAB建立对应的DRB传输，即E-RAB和DRB进行一一对应。LTE基站与UE之间的每个DRB对应的PDCP层协议采用LTE PDCP协议，RLC/MAC/PHY层则采用LTE RLC/MAC/PHY协议。
当LTE的基站连接到5GC时，5GC与LTE基站之间是按照PDU session建立隧道，对应的PDU session的数据包是按照流(flow)粒度进行区分(即一个PDU session中可能包括多个QoS flow)，每个下行数据包会携带对应的flow ID以及是否具有反射特性。所述反射特性是指UE是否可以根据下行的包属性(例如源IP地址，源端口，目的IP地址， 目的端口和传输层协议号等)与flow ID之间的映射关系推导出上行的包与flow ID之间的映射关系。同时，5GC要求LTE基站给5GC发送的数据包也携带flow ID，其目的是验证UE是否按照规定的方式把包映射到对应的flow ID中。
当LTE的基站连接到5GC时，对应的PDCP层应该采用NR PDCP协议，同时在NR PDCP层之前还增加SDAP层。RLC/MAC/PHY采用LTE RLC/MAC/PHY协议。
对于基站向终端发送的下行数据：终端的PDCP层或SDAP层会把在源小区或源基站正确接收的下行数据传递给高层。源小区或源基站会将没有正确发送的下行数据转移到源核心网，源核心网再把对应的下行数据转移到目标核心网，目标核心网再转移给目标小区或目标基站，或者源小区或源基站会将没有正确发送的下行数据转移直接转移给目标小区或目标基站，目标小区再在新的无线承载中把下行数据包发送给终端。
对于下行数据，源小区或源基站将未被终端确认接收的数据包通过目标小区重新发送，目标小区为这些包在无线协议重新分配一个序列号，且UE的PDCP层或SDAP层会把从源小区收到的数据包发送给上层，而不管其是否为乱序。比如数据包1、3、5提交给上层，UE的PDCP层或SDAP层从目标小区收到的数据包之后，再把这些从目标小区收到的数据包提交给上层。比如数据包2、4提交给上层，这样UE的上层收到这些数据包是乱序的，比如先收到数据包1、3、5，再收到数据包2、4。
为解决上述技术问题，本申请提供了以下技术方案，下面结合附图对本申请实施例的技术方案进行详细地说明。
本申请实施例的技术方案主要涉及的网元包括：终端、EPC、5GC、LTE eNB和eLTE eNB。其中，EPC和5GC表示两个不同的核心网，LTE eNB连接到EPC，即4G核心网，为终端提供无线接入服务；eLTE eNB连接到5GC，即5G的核心网，为终端提供无线接入服务。
在本申请的各个实施例中，涉及终端在EPC和5GC之间切换，包括：终端从EPC移动到5GC，或者从5GC移动到EPC。进一步地，当终端从EPC移动到5GC的过程中，位于核心网EPC的LTE eNB称为源基站，对应的核心网EPC称为源核心网；位于核心网5GC的eLTE eNB称为目标基站，对应的核心网5GC被称为目标核心网。反之，当终端从5GC移动到EPC时，所述源核心网为5GC，源基站为eLTE eNB，目标核心网为EPC，目标基站为LTE eNB。需要说明的是，在一种场景下，源基站和目标基站可以为同一个基站，即该基站即连接到EPC，也连接到5GC。
此外，本申请实施例的技术方案也适用于LTE eNB连接到EPC和gNB连接到5GC的场景。对应的网元主要包括：终端、EPC、5GC、LTE eNB和gNB。
在终端从EPC移动到5GC的过程中，连接到核心网EPC的LTE eNB称为源基站，对应的核心网EPC称为源核心网；连接到核心网5GC的gNB称为目标基站，对应的核心网5GC被称为目标核心网。反之，当终端从5GC移动到EPC时，所述源核心网为5GC，源基站为gNB，目标核心网为EPC，目标基站为LTE eNB。需要说明的是，源基站和目标基站可以为同一个基站，即该基站即连接到EPC，也连接到5GC。
另外，需要说明的是，由于协议中描述基站与核心网间的交互时，以及基站与基站交互时，都是用基站、核心网的文字描述。所以本申请中在这些描述时采用基站作为描述对象，而不采用源小区和目标小区作为描述对象。其他地方本申请实施例中仍然可以采用源小区和目标小区作为描述对象。
实施例一
如图3所示，本申请提供了一种数据传输方法。该方法可以应用于源基站，具体地，该方法包括：
步骤301：源基站确定第一数据和用于承载所述第一数据的数据单元的无线空口协议序列号。其中，所述第一数据包括：源基站与终端在数据传输过程中未被终端确认正确接收的数据，和/或所述源基站从终端接收的乱序的数据。
具体地，所述源基站向目标基站发送的第一数据包括：上行数据和/或下行数据。
所述下行数据对应无线空口协议序列号，例如PDCP层的序列号(Sequence Number,SN)的数据包，即所述第一数据可以划分为多个数据单元或数据包，每个数据单元或者数据包对应一个SN号；且所述SN号是由源基站分配的。
进一步地，所述由源基站分配SN号的第一数据包括：源基站向终端发送的但未收到终端反馈(haven’t been acknowledged by the UE)的数据，和/或，源基站已经分配了SN号，但是还未发送给终端的数据。
以终端从EPC切换到5GC为例，所述第一数据是以PDCP SDU的形式，即不包括PDCP的报头的数据包，源基站这些把PDCP SDU发送目标基站，同时还会包括指示第一数据的数据单元或数据包在源基站对应的SN号。
另外，所述上行数据还包括源基站从终端接收到的乱序的数据，所述乱序是指对于源基站从终端正确接收到的数据包之前有一些并没有被源基站正确接收的数据包。比如终端的应用层产生的数据包顺序为数据包1、2、3、4、5，源基站只正确接收到数据包1、3、5，终端在源基站发送了数据包2、4，但源基站并没有正确接收到数据包2、4，这样对于源基站而言，数据包3、5是乱序的，因为没有收到数据包2、4。
由于现有技术中，源基站并不会把这些乱序的数据包发给目标基站，源基站是直接把这些正确接收到的乱序数据包提交给核心网，所以这些数据包是乱序的。且终端在目标小区只发送那些在源小区没有发送的数据包(比如终端并不会在目标小区发送以上终端已经发送了但没有被源基站正确接收的数据包2、4)，对于那些发送过但没有被源小区正确接收的数据包就会被丢弃(比如以上的数据包2、4)，从而出现丢包。
本实施例，对于上行数据，以终端从EPC切换到5GC为例，所述第一数据是以PDCP SDU的形式进行说明，即不包括PDCP的报头等发送给目标基站，同时还会包括指示第一数据的数据单元或数据包在源基站对应的SN号。
步骤302：所述源基站向目标基站发送所述第一数据和所述无线空口协议序列号。
其中，所述目标基站所连接的核心网与所述源基站所连接的核心网不同，所述源基站和所述目标基站为所述终端在不同核心网切换过程中的源基站和目标基站。
具体地，所述源基站向目标基站发送所述第一数据和所述无线空口协议序列号，包括：源基站通过第一隧道向所述目标基站发送所述第一数据中的所述未被终端确认正确接收的数据以及所述无线空口协议序列号；和/或，通过第二隧道向所述目标基站发送所述第一数据中的所述来自所述终端的数据以及所述无线空口协议序列号。
其中，所述无线空口协议序列号可以在GTP-U(GTP User Plane,GTP-U)报头或扩展头中携带。
所述第一隧道和所述第二隧道可以是不同的隧道。进一步地，对于下行数据，源基站 通过用户面上的隧道(即第一隧道)发送第一数据中的下行数据包及对应的SN号给目标基站。对于上行数据，源基站通过用户面上的隧道(即第二隧道)发送第一数据中的上行数据包及对应的SN号。此外，在步骤302之前，源基站还会通过控制面信令通知目标基站哪些SN号范围内的上行数据包是被乱序接收的。
步骤303：所述目标基站接收来自源基站的第一数据和无线空口协议序列号。
其中，所述无线空口协议序列号为所述源基站确定的用于承载所述第一数据的数据单元的序列号。可选的，所述无线空口协议序列号可以是第一数据的数据单元或数据包的SN号。
步骤304：所述目标基站向所述终端发送所述第一数据和所述无线空口协议序列号。
本实施例提供的方法，由于源基站在向目标基站发送的数据中包括该数据的数据单元的无线空口协议序列号，且该无线空口协议序列号能够被终端识别，与终端从源基站中正确接收并确认的数据包具有一致的序列号，所以终端就能够根据这些序列号对从源基站正确接收的，和来自目标基站的且是从源基站转移给目标基站的那些在源基站未被终端确认正确接收的数据包进行排序，从而确保数据包的按序提交。
可选的，所述方法还包括：源基站确定第二数据，所述第二数据包括所述终端在核心网切换过程中，所述源基站从源核心网接收的待发送给所述终端的数据。
例如，终端从EPC切换到5GC的时间段内。EPC的LTE eNB从EPC接收的需要发送给终端的数据包，这些数据包还未被分配无线空口协议序列号，即SN号。源基站会通过控制面信令通知目标基站；对于这些数据包，接下来需要为其分配SN号，分配的原则可以按照源基站为终端分配的数据包的序列号的基础上，继续分配下一个序列号。比如指示目标基站对下一个没有分配SN号的数据包对应的SN号。另外，该下一个序列号可能通过下行计数count值来指示，该count值包括对应包的PDCP的SN号和超帧号。
比如，源基站为第一数据中的数据包分配的序列号是从SN_0至SN_100，则对于第二数据而言，目标基站为其继续分配的序列号从SN_101开始，以使得目标基站将这些分配有序列号的数据发送给终端后，终端能够正确地为这些数据排序。
所述方法还包括：所述源基站向所述目标基站发送所述第二数据，以使所述目标基站对所述第二数据按照所述第一数据对应的无线空口协议序列号，继续分配所述第二数据的数据单元的无线空口协议序列号。
一种具体地发送方式包括：所述源基站将所述第二数据通过用户面上的隧道(比如第一隧道)发送目标基站。
如图4所示，在本实施例，在步骤302：所述源基站向目标基站发送第一数据和无线空口协议序列号之前，所述方法还包括：
步骤401：源基站为终端配置第一无线承载信息，所述第一无线承载信息用于建立所述源基站和所述终端之间的无线承载。
步骤402：源基站向所述目标基站发送所述第一无线承载信息。其中，所述第一无线承载信息中包括所述无线承载的配置信息。
所述无线承载的配置信息至少包括无线承载标识、源基站为UE配置的PDCP层信息、源基站为UE配置的RLC层信息等中的至少一项。
可选的，源基站可以在给目标基站发送的切换请求消息中携带所述第一无线承载信 息。源基站也可以在给源核心网的切换需求消息中携带所述第一无线承载信息，之后源核心网再通知目标核心网，目标核心网在给目标核心网的切换请求消息中携带所述第一无线承载信息。
可选的，源基站给目标基站的消息(切换请求或者切换需求消息)中携带了请求数据转移的指示。
所述目标基站接收所述第一无线承载信息，并根据所述第一无线承载信息确定第二无线承载信息，以及生成确认消息，然后目标基站将该确认消息发送给源基站。
确认消息中携带所述第二无线承载信息。另外所述确认消息中还携带目标基站为接收从源基站转移第一数据的隧道信息。隧道信息包括传输层地址和GTP-TEID。此外，隧道信息还可区分接收上行和下行数据对应的隧道信息。
可选的，所述确认消息可以为目标基站在给源基站发送的切换请求确认消息；所述确认消息也可以为目标基站给目标核心网发送的切换请求确认消息，之后目标核心网再发消息给源核心网，该消息中携带所述第二无线承载信息和目标核心网分配的隧道信息。所述目标核心网分配的隧道信息是指目标核心网从源核心网接收转移数据的隧道信息。源核心网在给源基站的切换命令消息中携带所述第二无线承载信息和源核心网分配的隧道信息。所述源核心网分配的隧道信息是指源核心网从源基站接收转移数据的隧道信息。
此外，所述方法还包括：目标基站生成第三无线承载信息，所述第三无线承载信息包括终端与目标基站所连接的核心网交互的新数据的配置信息，例如该配置信息包括第二无线承载，用于为终端配置能够承载与目标核心网交互的新数据的无线资源。所述新数据为切换到目标核心网之后，UE的应用层产生的数据和从目标核心网接收到的且不是从源基站转移过来的数据。
步骤403：源基站接收所述目标基站反馈的确认消息。
其中，所述确认消息中可能携带用于指示所述目标基站和所述终端之间的第二无线承载信息，所述第二无线承载信息中包括无线承载的配置信息，该无线承载可用于承载所述第一数据，且该无线承载与所述第一无线承载信息中的无线承载可以相同，也可以不相同。比如无线承载的无线承载标识相同。
另外，所述第二无线承载信息还可用于指示对所述第一数据的接纳情况。
此外，所述确认消息中包括所述目标基站为所述终端配置的RRC重配消息，所述RRC重配消息包括终端需要在目标基站中接入的小区ID等。所述源基站在接收到来自目标基站的确认消息之后，将该确认消息中的RRC重配消息转发给所述终端。
所述确认消息中的RRC重配消息中可携带所述第二无线承载信息。
此外，所述确认消息中的RRC重配消息还包括用于所述第三无线承载信息。
步骤404：源基站向所述终端发送配置信息。
所述配置信息可以采用RRC重配信息。所述RRC重配消息可以为步骤403中源基站从目标基站收到的RRC重配消息。
可选的，所述配置信息还可以通过切换通知消息来发送给终端。
本实施例提供的方法，源基站通过向目标基站发送无线承载信息，以帮助目标基站配置其与终端的无线承载，进而利用该无线承载来传输第一数据，使得目标基站和终端都能够继续使用在源基站中的无线承载配置来传输或者存储第一数据，保证第一数据能在目标 基站继续保留和使用之前的序列号，从而保证了第一数据所对应的数据包按序递交。
实施例二
在本实施例中，对目标基站根据来自源基站的第一无线承载信息确定第二无线承载信息，以及向源基站反馈确认消息的过程进行详细地说明。
如图5所示，本实施例提供的方法是源基站与终端及目标基站与终端之间、源基站与目标基站如何处理切换时的数据，比如未被UE确认正确接收的下行数据包，对于源基站接收的来自终端的乱序的上行数据包，以保证下行数据包，和/或上行数据包的按序提交。
具体地，该方法包括以下步骤：
步骤501：源基站生成第一请求消息，例如切换需求消息，所述第一请求消息包括源基站为UE配置的无线承载配置。
所述第一请求消息还包括切换类型指示。切换类型指示用于指示是在同一制式的核心网下的不同基站之间的切换，或者指示对应不同制式核心网的两个基站间的切换。另外，所述切换类型指示还可以进一步指示是UE是从5GC切换到EPC，还是从EPC切换到5GC。
可选的，所述无线承载配置，可以通过第一无线承载信息来携带，用于建立所述源基站和所述终端之间的无线承载。
其中，如果UE是从5GC切换至EPC，则所述无线承载配置中包括：DRB标识、该DRB对应的NR PDCP配置信息和NR SDAP配置信息。进一步地，所述NR SDAP配置信息中包括：源基站为UE配置的DRB与QoS flow之间的映射关系，即包括指示UE或源基站将哪些QoS flow放到哪一个DRB上，以便利用对应的DRB传输Qos flow。例如有3个QoS flow，分别是flow 1，flow 2和flow 3，源基站会通过NR SDAP配置信息通知UE将flow 1和flow2的上行数据包放在DRB1上，将flow 3的上行数据包放在DRB2上，并进行相应的传输。
另外，所述NR SDAP配置信息中还包括以下至少任意一项：DRB承载的PDU session ID，SDAP上下行分别是否配置SDAP报文头，及该DRB是否为默认DRB。
其中，所述PDU session ID是指PDU session的标识。所述默认DRB是指当网络侧没有通知终端某个QoS flow的上行数据包对应到哪个DRB时，则UE把该QoS flow映射到该默认DRB上。所述网络侧没有通知终端某个QoS flow的上行数据包对应到哪个DRB是指，网络侧没有通过RRC消息指出该QoS flow对应的标识与DRB标识之间的映射关系，也没有通过用户面来指出该QoS flow的上行数据包映射到哪个DRB。
另一种切换方式，如果所述UE是从EPC切换至5GC，则所述无线承载配置中包括：源基站为UE配置的DRB配置。所述DRB配置具体包括：DRB标识、该DRB对应的源基站为UE配置的PDCP信息。
所述第一请求消息中还可以包括：不同核心网之间业务的映射关系，或者，包括请求源核心网和目标核心网之间确保某些EPC中的EPS承载对应的业务和5GC中的QoS flow对应的业务一一对应的请求信元。比如从EPC切换到5GC时，源小区可请求源核心网和目标核心网之间确保某些E-RAB ID里的所有数据包都映射到同一个QoS flow ID(例如E-RAB ID1与Qos flow ID2对应，E-RAB ID2与QoS flow ID1对应)。
其中，所述EPS承载是指4G中，用于标识具有相同业务处理特性(比如调度策略、排队管理策略等)的业务流。在EPC中业务分类的最小粒度是EPS承载，在该EPS承载中，核心网会为该EPS承载分配一个E-RAB标识给基站。所述QoS flow是指在5G中，UE的具 有相同业务处理特性(比如调度策略、排队管理策略等)的业务流。在5GC中业务分类的最小粒度是QoS flow，核心网5GC会为每个QoS flow分配一个QoS flow ID给基站。
可选的，所述第一请求消息中还包括：目标基站的标识，例如目标基站ID。
可选的，所述第一请求消息中还包括：请求数据转移的指示。
可选的，在第一请求消息中，所述第一无线承载信息可能是以一种容器(container)形式包含，也可能是直接以消息信元的方式携带，也可能一部分以container形式携带，一部分以消息信元携带。所述容器是指其中携带的信息可以通过核心网以透明形式传输到目标小区，即核心网无需知道消息里面具体内容的含义。
源基站将所述第一请求消息发送给源核心网。
步骤502：源核心网接收来自源基站的第一请求消息，并选择一个目标核心网，以及通过第二请求消息将所述第一请求消息中的一部分内容发送给所述目标核心网。
其中，第一请求消息中的一部分内容包括如下至少一种：切换类型指示，源基站为UE配置的无线承载配置，不同核心网之间业务映射关系，目标基站的标识。
步骤503：目标核心网接收来自源核心网的第二请求消息，并通过第三请求消息将所述第二请求消息中的一部分内容发送给目标基站。
由于所述第二请求消息中包含目标基站的标识，即目标基站ID，所以目标核心网能够确定目标基站，并发送所述第三请求消息。
进一步地，所述第二请求消息中的一部分内容包括以下至少任意一项：切换类型指示，源基站为UE配置的无线承载配置，请求数据转移的指示。
另外，所述第三请求消息中还可能包括目标核心网通知目标基站建立的业务QoS相关信息。例如，如果目标核心网是5GC，则业务QoS相关信息包括PDU session ID,QoS flow ID及该QoS flow对应业务质量信息(比如保证速率、最大速率、优先级等)。如果目标核心网是EPC，则业务QoS相关信息包括E-RAB ID，及该E-RAB对应的业务质量信息。
步骤504：目标基站接收来自目标核心网的第三请求消息，并根据所述第三请求消息中的内容为UE分配相应的无线资源配置，并生成第一确认消息，例如切换请求确认消息，所述第一确认消息中包括第二无线承载信息。
其中，所述为UE分配的相应无线资源配置(即第二无线承载信息)包括如下至少一种：LTE PDCP配置，和NR PDCP配置，NR SDAP配置。
进一步地，所述LTE PDCP配置包括LTE PDCP层的一些配置(比如丢包定时器，头压缩配置，PDCP层序列号长度等)；所述NR PDCP配置包括NR PDCP层的一些配置(比如丢包定时器长度，头压缩配置，PDCP层序列号长度，完整性保护配置，失序提交配置，排序定时器长度等)。
如图6a所示，对于UE从EPC切换至5GC的无线承载配置，目标基站根据来自目标核心网的第三请求消息确定UE的无线资源承载，包括：目标基站根据原DRB1为UE配置的DRB1_1(比如DRB标识相同，DRB的PDCP配置也可相同)，该DRB1_1用于承载未被UE确认正确接收的数据包；还包括当UE切换到5GC时，源基站从源核心网EPC接收的数据包。
此外，目标基站还生成DRB2，该DRB2中包括NR_PDCP配置信息，用于承载核心网5GC中的数据。
可选的，所述目标基站还为UE分配多个DRB，其中一部分DRB使用LTE PDCP配置， 一部分使用NR PDCP和NR SDAP配置。其中，所述无线资源配置还包括以下至少一项：E-RAB ID、DRB ID、DRB ID和QoS flow ID之间的对应关系、DRB ID和PDU session ID之间的对应关系。
如图6b所示，对于UE从5GC切换至EPC的无线承载配置，目标基站保留原DRB1以及该DRB1的配置信息，同时生成DRB2，该新生成的DRB2中包括LTE PDCP层和LTE RLC层，用于承载核心网EPC中的数据。
另外，所述第一确认消息中还携带目标基站为接收从源基站转移第一数据的隧道信息。所述隧道信息包括传输层地址和GTP-TEID。进一步地，所述隧道信息还可区分接收上行数据和下行数据对应的隧道信息。
可选的，所述第一确认消息中还包括：目标基站对源基站发送的无线承载的接纳情况，比如指示接纳哪些无线承载，以及还可以指示不接纳哪些无线承载的情况。
在前述方法的步骤504之后，还包括：目标基站将为UE分配的第二无线承载信息发送给目标核心网。
可选的，所述第二无线承载信息可以通过第一确认消息来承载。
可选的，所述第二无线承载信息中包括第三无线承载配置信息。
可选的，目标基站向目标核心网发送第二无线承载信息(包括第三无线承载配置信息)的具体方式包括：一种方式是以container形式包含发送；另一种方式也可以是直接以消息信元的方式携带；或者，还可以通过一部分以container形式携带，一部分以消息信元携带这种混合的方式，本实施例对具体采用哪种方式发送不予限制。
步骤505：所述目标核心网接收来自目标基站的第一确认消息，并生成第二确认消息，所述第二确认消息至少包括所述第一确认消息中的一部分，以及向所述源核心网发送所述第二确认消息。
该步骤505与现有流程相同。
可选的，所述第二确认消息还可以包括：数据转移隧道信息，所述数据转移隧道消息包括传输层地址(即IP地址)、GTP-TEID等。
可选的，所述第二确认消息还可以包括：目标基站为UE分配的无线资源配置，无线资源配置中可以包括LTE PDCP配置、NR PDCP配置、NR SDAP配置中至少一个。所述无线资源配置与源基站为UE配置的无线资源配置可能不相同，即所述无线资源配置中可以只包括与源基站为UE配置的无线资源配置中不同的信息。
步骤506：源核心网接收来自所述目标核心网的第二确认消息，生成第三确认消息，以及向源基站发送所述第三确认消息，所述第三确认消息中至少包括所述第二确认消息中的一部分。
源核心网根据第二确认消息中的接纳情况，为接纳的PDU session或者QoS flow或者DRB分配在源核心网侧的数据转移隧道信息，并将该数据转移隧道信息配置在所述第三确认消息中。
可选的，源核心网和目标核心网采用相同的数据隧道信息，比如源核心网的用户面和目标核心网的用户面在同一模块中。
此外，所述第三确认消息中还包括以下第二确认消息中的至少一项：目标基站对目标核心网的业务QoS的接纳请求，目标基站对源基站发送的无线承载配置的接纳情况，目标 基站为UE分配的无线资源配置。
例如，终端从5GC切换到EPC，第三确认消息可携带哪些DRB被目标小区接纳了，哪些被拒绝了。如果终端从EPC切换到5GC，该消息可携带哪些E-RAB被目标小区接纳了，哪些被拒绝了。或者也可携带哪些QoS flow被目标小区接纳了，哪些被拒绝了等信息。
可选的，所述第三确认消息的消息类型可以为切换命令handover command。
步骤507：源基站接收来自源核心网的第三确认消息，并生成切换通知，以及将所述切换通知下发给UE。
所述切换通知中包括第三确认消息中的目标基站为UE分配的无线资源配置。
此外，所述切换通知可以是RRC重配消息。进一步地，所述RRC重配消息中包括：UE切换到目标核心网下的目标基站之后，目标小区或目标基站为UE配置的第二无线承载信息和/或第三无线承载信息。
步骤508：源基站向目标基站发送数据和所述数据的数据单元对应的无线空口协议序列号。
该步骤508中的数据发送包括上行数据和下行数据两个方向的传输，下面对这两个方向的数据传输进行说明。
(1)下行数据
对于下行方向，所述数据包括第一数据和第二数据。其中，所述第一数据为：具有源基站分配的SN号，且所述源基站与终端在数据传输过程中未被终端确认正确接收的数据。所述第二数据为：终端在核心网切换过程中，所述源基站接收的待发送给终端的数据，这些数据还未分配SN号，所以需要目标基站根据源基站之前分配的SN号继续为第二数据分配SN号。
可选的，源基站在转移这些数据包时，也是按序转移这些数据包的，比如按照源基站从源核心网接收的先后关系进行转移的。
进一步地，所述未被终端确认正确接收的数据包括：源基站已经分配了SN的PDCP SDU(PDCP层已经为PDCP SDU分配了SN)并发送给终端，但是未接收到终端反馈的数据包，和/或，源基站已经分配了带有SN号，但是还未发送给终端的数据包。
A.在终端从EPC切换至5GC(即4G切换至5G)过程中
源基站将所述第一数据、所述第二数据以及他们对应的SN号通过DRB，或者E-RAB隧道发送给目标基站(目标小区)。
可选的，所述源基站在发送完数据和所述数据对应的SN号之后，方法还包括：源基站发送至少一个结束标识(end marker)包到目标基站或目标小区，所述结束标识包用于指示源基站结束在该隧道上转移数据，即后续没有数据在该隧道上转移给目标基站。可选的，源基站从源核心网收到一个end marker之后，源基站才发送所述至少一个结束标识包到目标基站或目标小区。
可选的，所述方法还包括：所述源基站向目标基站发送一个状态转移消息，该状态转移消息用于指示上行PDCP SN和超帧号的接收状态以及下行PDCP SN和超帧号的发送状态。该状态转移消息可能通过源核心网和目标核心网发送到目标基站。
其中，该状态转移消息中携带了如下至少一项：源基站需要进行数据转移的DRB ID，目标基站在该DRB对应下行数据包分配的下一个计数count值，该count值包括对应包的 PDCP的SN号和超帧号、源基站在该DRB对应上行数据包接收情况(没有正确接收的第一个PDCP包对应的计数count值，该count值包括对应包的PDCP的SN号和超帧号，及该PDCP包之后其他数据包的上行接收情况)。其中，所述状态转移消息一般在源基站向目标基站转移数据包之前发送。
进一步地，如图7所示，在UE从EPC切换至5GC的过程中，从源基站传输至目标基站的数据，包括：
第一数据：未被终端确认正确接收的数据且携带PDCP序列号SN的数据包，即PDCP SDU with SN，例如，SN_n，SN_n+1，SN_n+2。
和/或，第二数据：从EPC下来的新的数据包，所述第二数据中不带PDCP SN，即PDCP SDU without SN。例如，packet_1，packet_2，packet_3。
目标基站可以通过DRB1_1(使用LTE PDCP)继续传输给UE。
此外，当UE切换到核心网5GC后，传输给所述目标基站的数据还包括：第三数据。
所述第三数据为从5GC新下来的数据(即以5GC的格式下发的数据包)，对于这些数据包可以通过DRB2(使用NR PDCP)传输。例如，flow 1的三个数据包flow 1_1/flow1_2/flow 1_3。
目标基站获取所述第一数据、第二数据、结束标识以及第三数据，目标基站先在为UE配置的DRB1_1中发送第一数据中的数据包，再在为UE配置的DRB1_1中发送第二数据中的数据包。另外，目标基站将获取的第三数据flow 1_1/flow 1_2/flow 1_3承载在DRB2中。
本实施例中，由于目标基站使用LTE PDCP的DRB可以继续使用源基站为终端在该DRB分配的PDCP SN号，目标基站再通过该DRB将数据传输给终端，终端能够识别且可以按照该SN顺序把数据提交给上层，从而保证数据包按序提交。
B.在终端从5GC切换至EPC(即5G切换至4G)的过程中
源基站(例如eLTE eNB)向目标基站(LTE eNB)传输的数据，包括：第一数据，所述第一数据为未被终端确认正确接收的PDCP SDU，且携带有SN号。
其中，所述源基站中包括源小区，所述目标基站中包括目标小区。
可选的，这些数据包可以通过DRB或者E-RAB隧道传输至目标基站。
所述源基站向目标基站传输的数据，还包括：源基站将从源核心网5GC过来的新的QoS flow数据包且该QoS flow被目标小区接纳进行数据转移(data forwarding)。
可选的，源基站通过DRB或者E-RAB隧道将新的QoS flow数据包传输至目标基站，或者通过PDU session隧道传输至目标基站。
可选的，源基站从源核心网收到一个或多个end marker之后，如果源基站和目标基站之间建立了PDU session隧道，则源基站把这些end marker通过对应的PDU session隧道转移给目标基站。如果源基站和目标基站之间建立了DRB隧道，则在没有其他数据包需要通过DRB隧道转移到目标基站时，源基站会产生一个或多个end marker，并通过对应的DRB隧道发送给目标基站。
可选的，源基站从源核心网收到一个或多个end marker之后，源基站会把这些end marker复制到源基站和目标基站的各个隧道(包括DRB隧道或者E-RAB隧道或者PDU session隧道中至少一种)中。
可选的，所述方法还包括：源基站向目标基站发送一个状态转移消息，该状态转移消息用于指示上行PDCP SN和超帧号的接收状态以及下行PDCP SN和超帧号的发送状态。该状态转移消息可能通过源核心网和目标核心网发送给目标基站。
其中，所述状态转移消息中携带了如下至少一项：源基站需要进行数据转移的DRB ID，目标基站在该DRB对应下行数据包分配的下一个计数count值，该count值包括对应包的PDCP的SN号和超帧号、源基站在该DRB对应上行数据包接收情况，例如，未被正确接收的第一个PDCP包对应的计数count值，该count值包括对应包的PDCP的SN号和超帧号及该PDCP包之后，其他数据包的上行接收情况。其中，所述状态转移消息一般在源基站向目标基站转移数据包之前发送。
本实施例中，对于从源基站转移过来的数据，目标基站可以采用使用NR PDCP、NR SDAP的DRB发送这些数据；对于从目标核心网传输给目标基站的新数据(即以EPC的格式下发的数据包),可以采用使用LTE PDCP的DRB传输。
由于目标基站使用NR PDCP、NR SDAP的DRB可以继续使用源基站为终端在该DRB分配的PDCP SN号，且终端可以按照该SN顺序把数据提交给上层，从而保证数据包按序提交。
(2)上行数据
对于上述步骤508中，源基站(或源小区)向目标基站传输数据的过程，具体包括：
所述需要传输的数据包括第一数据，所述第一数据中包括：源基站从终端接收到的乱序的数据，所述乱序是指对于源基站从终端正确接收到的数据包之前有一些并没有被源基站正确接收的数据包。
可选的，这些数据包可以通过DRB或者E-RAB隧道传输至目标基站。这些数据包是以PDCP SDU形式转移给目标基站，且在转移时携带了PDCP SDU对应的SN号。
需要说明的是，在上述步骤508中，源基站与目标基站之间进行上下行数据转移的方式包括以下两种：
一种方式是：在目标基站和源基站之间直接进行，即源基站将数据和数据对应的序列号直接发送给目标基站。
另一种方式是：目标基站和源基站通过源核心网和目标核心网间接进行，即源基站将数据和数据对应的序列号先发送给源核心网，源核心网接收后再将这些数据和数据对应的序列号发送至目标核心网，所述目标核心网再将所述数据和所述序列号发送给目标基站。
具体地，采用哪种方式传输方式，可以由源核心网和目标核心网的内部配置决定，或者，也可以根据协议规定选择哪一种传输方式。
如图5所示，所述方法还包括：
步骤509：终端UE接收来自源基站的切换通知，并向目标基站发送切换完成消息，表明UE已经做好数据传输的准备。
具体地，UE根据所述切换通知中携带的目标小区ID确定目标小区，然后与所述目标小区建立通信连接。
其中，所述切换通知可以是现有的消息类型，比如RRC重配消息。进一步地，所述RRC重配消息中包括目标小区或目标基站为UE配置的无线承载配置信息。所述无线承载配置信息包括第二无线承载信息和/或第三无线承载信息。
步骤510：目标基站与终端UE之间进行数据传输。
具体地，所述数据传输包括：对于下行方向的数据传输，和对于上行方向的数据传输。
首先介绍对于下行方向的数据传输的具体过程：
(1)下行数据：
对于UE从EPC切换到5GC的过程:
在目标基站侧配置的两种无线承载信息，一种是第二无线承载配置信息中的无线承载用于承载来自源基站或源小区转移过来的第一数据和/或第二数据。另一种是第三无线承载配置信息中的无线承载，用于承载5GC新下来的数据包，即SDAP SDU。
其中，所述第二无线承载配置信息可以与源基站为UE配置的第一无线承载信息相同，也可以不相同。
为了保证UE按照数据包的顺序向上层提交数据，目标基站(目标小区)先将第一数据和/或第二数据通过第二无线承载配置信息中的无线承载发送给UE，待UE确认正确接收了这些数据包之后，再将5GC新下来的数据包通过第三无线承载配置信息中的无线承载发送给UE。
具体地，目标基站确定第一数据和/或第二数据是否被UE正确接收的过程包括：
一种可能的实现方式是：目标基站通过RLC层的状态信息来确定UE的接收情况，进一步地，UE在接收到来自目标基站的数据包之后会向所述目标基站发送RLC状态信息，所述RLC状态信息中指示UE接收的数据包；目标基站接收UE反馈的状态信息后，根据所述状态信息的指示能够确定数据包是否被正确接收。例如，每个数据包中包括一个标识，该标识用于指示UE正确接收到目标基站发送的数据包。
另一种可能的实现方式是：目标基站通过MAC层的ACK来判断数据包是否被UE正确接收了。具体包括：如果目标基站接收到来自UE的ACK，则认为UE正确接收了数据包；否则，认为UE没有正确接收到数据包。
此外，还可以通过其它方式反馈UE是否正确接收DRB资源的数据包，本申请实施例对于具体实现方式不进行限定。
切换到目标基站之后，由于UE连接的核心网已经从EPC切换到5GC,所以UE的无线协议层之上的协议层接收数据包的方式变为了连接到5GC时接收数据包的方式。UE从第二无线承载信息中的无线承载收到的下行数据应该以连接到5GC的方式提交给上层。
比如，UE根据E-RAB ID和PDU session ID/QoS flow ID之间对应的关系确定把从第二无线承载信息中的无线承载收到的下行数据包通过哪一个SDAP实体与上层的接口提交给上层，无需通知该包的反射特信息和flow ID。
或者，UE根据E-RAB ID和PDU session ID/QoS flow ID之间对应的关系，确定把从第二无线承载信息中的无线承载收到的下行数据包提交给哪一个SDAP实体，该SDAP实体再把从第二无线承载信息中的无线承载收到的这些下行数据包提交给上层，该SDAP实体提交下行数据包给上层时，无需通知该包的反射特信息和flow ID。
对于UE从5GC切换到EPC的过程:
在目标基站侧配置的两种无线承载信息，一种是第二无线承载配置信息中的无线承载用于承载来自源基站或源小区转移过来的第一数据和/或第二数据，另一种是第三无线承载配置信息中的无线承载，用于承载EPC新下来的数据包，即LTE PDCP SDU。
为了保证UE按照数据包的顺序向上层提交数据，目标基站(目标小区)先将第一数据和/或第二数据通过第二无线承载配置信息中的无线承载发送给UE，待UE确认正确接收了这些数据包之后，再将EPC新下来的数据包通过第三无线承载配置信息中的无线承载发送给UE。
具体地，目标基站确定第一数据和/或第二数据是否被UE正确接收的过程与UE从EPC切换到5GC的过程中的描述相同，此处不再赘述。
切换到目标基站之后，由于UE连接的核心网已经从5GC切换到EPC，所以UE的无线协议层之上的协议层接收数据包的方式变为了连接到EPC时接收数据包的方式。UE从第二无线承载信息中的无线承载收到的下行数据应该以连接到EPC的方式提交给上层。
比如，UE根据E-RAB ID和PDU session ID/QoS flow ID之间对应的关系确定把从第二无线承载信息中的无线承载收到的下行数据通过哪一个LTE PDCP实体与上层的接口提交给上层，无需通知该包的反射特信息和flow ID。
或者，UE根据E-RAB ID和PDU session ID/QoS flow ID之间对应的关系确定把从第二无线承载信息中的无线承载收到的下行数据包提交给哪一个LTE PDCP实体，该LTE PDCP实体再把从第二无线承载信息中的无线承载收到的下行数据包提交给上层，该LTE PDCP实体提交这些下行数据包给上层时，无需通知该包的反射特信息和flow ID。
(2)上行方向：
步骤510中，目标基站与UE之间的数据传输，包括：UE从EPC切换到5GC过程中的数据传输，和UE从5GC切换到EPC过程中的数据传输。
对于UE从EPC切换到5GC过程的数据传输：具体包括：UE通过第二无线承载信息中的无线承载向目标基站重新发送那些在源小区没有被源小区确认正确接收的LTE PDCP SDU，可选的可以进一步排除那些被目标基站确认已经正确接收的LTE PDCP SDU，并且，通过第三无线承载信息中的无线承载向目标基站发送上层新下来的数据包，即SDAP SDU。
对于UE从5GC切换到EPC过程的数据传输，具体包括：UE通过第二无线承载信息中的无线承载向目标基站重新发送那些在源小区未被源小区确认正确接收的NR PDCP SDU，可选的可以进一步排除那些被目标基站确认已经正确接收的NR PDCP SDU；并且通过，第三无线承载信息中的无线承载向目标基站发送上层新下来的数据包，即LTE PDCP SDU.
可选的，为了保证基站按照数据包的顺序向上层提交数据。UE可以先在第二无线承载信息中的无线承载传输未成功发送的PDCP SDU，确认这些数据包被基站正确接收之后，再在第三无线承载信息中的无线承载上传输新的数据包。
另外一种可能是，UE在第二无线承载信息中的无线承载传输未成功发送的PDCP SDU，同时可以在第二无线承载信息中的无线承载中发送一个结束标识，例如，可能通过SDAP层或者PDCP层或者RLC层来指示，比如通过这些层中的包头中的比特来指示，或者通过这些层的某个不带净荷的PDU来指示，或者通过这些层的控制PDU来指示。进一步的，还可以指示是哪一个QoS flow的数据包结束。UE可以同时在第三无线承载信息中的无线承载上传输新的数据包，即无需确认在第二无线承载信息中的无线承载传输的数据包被基站正确接收之后，才开始在第三无线承载信息中的无线承载上的传输新的数据包。
在UE从EPC切换到5GC之后，由于目标基站连接的核心网是5GC，所以目标基站提交给核心网的数据包的方式应该按照连接到5GC的形式提交。目标基站从第二无线承载信息 中的无线承载收到的上行数据应该以连接到5GC的方式提交给核心网。
比如，目标基站根据E-RAB ID和PDU session ID/QoS flow ID之间对应的关系确定把从第二无线承载信息中的无线承载收到的上行数据包通过哪一个PDU session对应的隧道发送给目标核心网5GC，并且为每个数据包增加QoS flow ID，例如，根据E-RAB ID和PDU session ID/QoS flow ID之间对应的关系确定。
或者，目标基站根据E-RAB ID和PDU session ID/QoS flow ID之间对应的关系确定把从第二无线承载信息中的无线承载收到的上行数据包提交给哪一个SDAP实体，该SDAP实体再把从第二无线承载信息中的无线承载收到的上行数据包提交给目标核心网，该SDAP实体提交这些上行数据包给核心网时，为每个数据包增加QoS flow ID，例如，根据E-RAB ID和PDU session ID/QoS flow ID之间对应的关系确定。
在UE从5GC切换到EPC之后，由于基站与核心网之间的接口已经变成了EPC的接口，所以基站在旧的DRB上收到的数据包之后，需要按照新的数据包格式提交。比如目标基站根据E-RAB ID和PDU session ID/Qos flow ID之间对应的关系知道把使用NR PDCP的DRB的SDAP实体上接收的上行数据包通过哪一个使用LTE PDCP的PDCP实体与上层的接口提交给核心网，且以EPC的GTP-U格式发送给核心网。可选的，提交给核心网时，无需携带flow ID。
UE切换到目标基站之后，由于目标基站连接的核心网是EPC,所以目标基站提交给核心网的数据包的方式应该按照连接到EPC的形式提交。目标基站从第二无线承载信息中的无线承载收到的上行数据应该以连接到EPC的方式提交给核心网。
比如，目标基站根据E-RAB ID和PDU session ID/QoS flow ID之间对应的关系确定把从第二无线承载信息中的无线承载收到的上行数据包通过哪一个E-RAB对应的隧道发送给目标核心网EPC，无需携带flow ID。
或者，目标基站根据E-RAB ID和PDU session ID/QoS flow ID之间对应的关系确定把从第二无线承载信息中的无线承载收到的上行数据包提交给哪一个LTE PDCP实体，该LTE PDCP实体再把从第二无线承载信息中的无线承载收到的上行数据包提交给目标核心网，该LTE PDCP实体提交这些上行数据包给核心网。可选的，提交给核心网时，无需携带flow ID。
可选的，目标基站先将所述第二无线承载信息中的无线承载的数据都提交给目标核心网，然后再将第三无线承载信息中的无线承载的数据提交给目标核心网。比如可以在第二无线承载信息中的无线承载上收到end marker之后，目标基站再将第三无线承载信息中的无线承载的数据提交给目标核心网。
步骤511：UE接收来自目标基站的数据以及数据包所对应的序列号，并将所述数据包按照序列号顺序递交给高层。
本实施例提供的方法，目标基站通过源基站的第一无线承载信息为UE配置第二无线承载信息，所述第二无线承载信息中的DRB用于从源基站转移过来的第一数据和/或第二数据，且这些数据保留源基站分配的SN号，所以接收端目标基站可以通过该DRB向UE发送这些数据包，从而保证包不丢失，且UE可以按照该序列号的顺序对切换核心网前后获取的所有数据包进行排序，进而保证了所有数据包能够按序提交给上层。
此外，目标基站还通过建立第三无线承载信息，该第三无线承载信息中的无线承载用 于承载切换至目标核心网的数据，从而目标核心网的数据可以在目标基站上以新的无线承载传输，避免与源核心网中的数据包产生乱序，进一步地保证发送给UE的数据包的有序性。
例如在上述步骤510中，UE首先是把从第二无线承载信息中的无线承载上接收的数据提交高层，之后再把从第三无线承载信息中的无线承载上接收的数据提交高层，进而保证了数据包的按序提交。
可选的，上述实施例中，步骤511之后还可以包括以下步骤：
步骤512：目标基站向目标核心网发送切换完成消息。
所述切换完成消息用于通知目标核心网，UE已经完成不同核心网之间的切换。其中，所述切换完成消息可以是现有的消息类型，比如切换指示(handover notify)，路径切换请求(path switch request)，重定位完成(relocation complete)等，还可以是新定义的消息类型。
步骤513：目标核心网与源核心网之间的信息交互。
该交互过程可以采用现有的流程。
步骤514：源核心网向源基站发送结束标识(end marker)包。
该end marker包用于通知目标小区，源核心网已经停止了向源基站发送数据包(即后续没有数据包发送给源基站)。
可选的，源核心网可以向源基站发送一个或多个结束标识包。
对于源核心网为EPC而言，是每个E-RAB隧道会有一个end marker包。对于核心网5GC而言，可能是每个PDU session对应一个end marker包，即后续没有该PDU session的任何数据包发送给源基站。也可能每个QoS flow对应一个end marker包,即后续没有该QoS flow的包发送给源基站。
可选的，源核心网可以在GTP-U报头中携带指示该包为end marker包。
需要说明的是，上述实施例中，步骤507和508之间没有严格的先后关系，即可以先执行步骤508，再执行步骤507。此外，步骤510、511、512之间也没有严格的先后关系，即可以先执行步骤512、再执行步骤510和步骤511，也可以先执行步骤510、步骤511，再执行步骤512。
但需要强调的是，在步骤510中，目标基站在向终端传输数据时，必须要在接收到UE发送的切换完成消息之后进行，从而保证UE能与目标基站之间进行数据传输。
在步骤514之后，源基站收到源核心网发送的end marker包之后，源基站再给目标基站发送end marker包，具体过程参见步骤508中的描述，此处不再赘述。
实施例三
本实施例是针对实施例一和实施例二中源基站和目标基站为同一个基站的应用场景，即本实施例的基本步骤与前述实施例一和实施例二的方法基本相同，即数据的发送和目标基站为UE配置无线承载信息的方法都相同。区别仅在于，UE切换核心网之后，对于该UE而言，基站可以通过两套传输端口分别进行与源核心网和目标核心网的数据传输，具体如下：
UE在切换过程中，对于该UE而言，基站与两个核心网间都通过数据传输通道建立连接，所以该基站会把发送给源核心网的数据提交给源核心网，把发送给目标核心网的数据 提交给目标核心网。
本实施例中，参见图9，UE在连接到两个核心网的同一个基站之间切换的场景：主要用于两个核心网之间的负荷分担场景，即分担每个核心网的负荷。比如UE接收到基站中源小区和目标小区的信号质量没有大的改变(源小区和目标小区可能是同一个小区，也可能是不同的小区)，但是由于UE原来连接的EPC负荷比较高，所以网络侧决定把UE连接的核心网改为5GC。
如图8所示，以源基站和目标基站为同一个基站为例，所述方法具体包括：
步骤801：基站向源核心网发送切换需求消息。
该切换需求消息可以是现有的消息，比如handover required，所述切换需求消息也可以是新定义的其他消息，比如重定位请求(relocation request)。
所述切换需求消息中可携带切换到目标核心网的请求，也可能携带切换过程中基站保持与两个核心网的数据传输通道的请求，即该UE同时连接到两个核心网5GC和EPC。
在步骤801之前，还包括：基站为UE配置第一无线承载信息，所述第一无线承载信息用于建立所述基站和所述UE之间的无线承载。
步骤802：源核心网接收所述切换需求消息，并与目标核心网之间进行交互消息。
步骤803：目标核心网与源核心网进行消息交互之后，向基站发送切换请求消息。该消息中携带通知基站对于将UE同时连接到两个核心网5GC和EPC。
步骤804：基站向目标核心网发送切换请求确认消息。
步骤805：基站接收所述切换请求确认消息，并向UE发送切换通知。
其中切换通知消息中可包含如下内容中的至少一项：
第四无线承载信息，所述第四无线承载信息是基站根据第一无线承载信息生成的。第四无线承载信息包括：无线承载的配置信息，无线承载的配置信息至少包括无线承载标识、基站为UE配置的连接到源核心网对应的PDCP层信息(比如，UE从5GC切换到EPC时，为NR PDCP层信息)、基站为UE配置的RLC层信息、保持第一无线承载相关的配置的指示等中的至少一项。
其中，所述第四无线承载信息中的无线承载，用于承载源核心网中的数据。对于下行传输，是从源核心网下来的新数据及在切换之前未被UE确认正确接收的下行PDCP SDU，对于上行传输，是UE在切换之前没有收到基站确认正确接收的上行PDCP SDU。
第五无线承载信息，第五无线承载信息是基站根据目标核心网通知的内容生成的无线承载信息。第五无线承载信息包括：无线承载的配置信息，所述无线承载的配置信息至少包括：无线承载标识、基站为UE配置的连接到目标核心网对应的PDCP层信息(比如，UE从5GC切换到EPC时，为LTE PDCP层信息)、基站为UE配置的RLC层信息等中的至少一项。
所述第五无线承载信息中的无线承载用于承载切换到目标核心网之后的数据包。对于下行传输，是从目标核心网下来的新数据，对于上行传输，是UE从应用层收到的新数据。
步骤806：UE向基站发送切换完成消息，该步骤用于UE通知基站已经完成切换。
步骤807：基站与UE之间进行数据传输，所述数据传输包括上行数据和/或下行数据。
下行方向数据传输：
基站侧有两种下行数据需要发送，一种是从源核心网下来的新数据和/或在切换之前 未被UE确认正确接收的下行PDCP SDU，称为第四数据；一种是从目标核心网下来的新数据，称为第五数据。
基站侧配置的两种无线承载，一种是第四无线承载信息中的无线承载，用于承载第四数据；一种是第五无线承载信息中的无线承载，用于承载第五数据。
为了保证UE按照数据包的顺序向上层提交数据，基站先将第四数据通过第四无线承载配置信息中的无线承载发送给UE，待UE确认正确接收了这些数据包之后，再将第五数据通过第五无线承载配置信息中的无线承载发送给UE。
具体地，基站确定第四数据是否被UE正确接收的过程包括：
一种可能的实现方式是：基站通过RLC层的状态信息来确定UE的接收情况，进一步地，UE在接收到来自基站的数据包之后会向所述基站发送RLC状态信息，所述RLC状态信息中指示UE接收的数据包；所述基站接收UE反馈的状态信息后，根据所述状态信息的指示能够确定数据包是否被正确接收。例如，每个数据包中包括一个标识，该标识用于指示UE正确接收到基站发送的数据包。
另一种可能的实现方式是：基站通过MAC层的ACK来判断数据包是否被UE正确接收了。具体包括：如果基站接收到来自UE的ACK，则认为UE正确接收了数据包；否则，认为UE没有正确接收到数据包。
此外，还可以通过其它方式反馈UE是否正确接收DRB资源的数据包，本申请实施例对于具体实现方式不进行限定。
UE切换到目标基站之后，由于UE连接的核心网已经变化了,具体方法同实施例二中的步骤510。
上行方向数据传输：
UE通过第四无线承载信息中的无线承载向基站重新发送那些没有被基站确认正确接收的PDCP SDU；并且通过第五无线承载信息中的无线承载向基站发送上层新下来的数据包。
一种可能的实现方式中，为了保证基站按照数据包的顺序向上层提交数据，UE可以先在第四无线承载信息中的无线承载传输未成功发送的PDCP SDU，确认这些数据包被基站正确接收之后，再在第五无线承载信息中的无线承载上传输新的数据包。
另外一种可能实现方式是，UE在第四无线承载信息中的无线承载传输未成功发送的PDCP SDU，同时UE可以在第二无线承载信息中的无线承载中发送一个结束包，例如，所述结束包通过SDAP层或PDCP层或RLC层来指示，进一步地，可通过这些层包头中的比特来指示，或者通过这些层的某个不带净荷的PDU来指示，或者通过这些层的控制PDU来指示。
可选的，UE还可以同时在第五无线承载信息中的无线承载上传输新的数据包，即无需确认在第四无线承载信息中的无线承载中传输的数据包是否被基站正确接收，就可以在第五无线承载信息中的无线承载上的传输新的数据包。
可选的，基站把从第四无线承载信息中的无线承载中收到的数据包提交给源核心网，把从第五无线承载信息中的无线承载中收到的数据包提交给目标核心网的过程，具体包括：
基站可以在第四无线承载信息中的无线承载中的所有上行数据包都提交给源核心网之后，再把从第五无线承载信息中的无线承载中收到的数据包提交给目标核心网。
或者，基站也可以同时把从两种无线承载中的数据包分别提交给两种核心网，但在结束第四无线承载信息中的无线承载中收到的数据包之后，基站给源核心网发送一个结束标识包(end marker)包。该结束标识包用于指示某个E-RAB或者某个PDU session或者flow的数据包的传输结束。源核心网收到这个结束标识包之后，再通知目标核心网可以把从基站收到的对应该E-RAB或者PDU session或者flow的数据包提交给其他实体(比如与UE通信的对端)。
步骤808：基站向目标核心网发送切换完成消息。
该步骤同实施例二中的步骤512，本实施例不再赘述。
步骤809：目标核心网与源核心网交互信息。
该步骤同实施例二中的步骤513，其主要用于目标核心网通知源核心网，UE已经切换并接入到了目标核心网。
步骤810：源核心网向基站发送end marker包。
该步骤同实施例二中步骤514，参考前述实施例二中步骤514的描述，本实施例不再赘述。
本实施例提供的方法，基站通过数据传输通道同时与核心网EPC和5GC建立通信连接，且基站可以通过两套端口分别与EPC和5GC进行通信，从而使得基站也可以同时把从两种无线承载中的数据包分别提交给两种核心网，提高了数据传输效率。
实施例四
本实施例是针对实施例一和实施例二中源基站和目标基站为同一个基站的应用场景，例如图9所示。与实施例二中为UE配置无线资源承载信息和传输数据的方法相同，区别仅在于，本实施例中的目标基站和源基站为同一个基站，即本实施例所述的基站具有源基站和目标基站的功能。
本实施例与实施例三的区别在于，实施例三是一个基站同时与源核心网和目标核心网相连接，而本实施例是，UE在切换过程中，对于该UE而言，基站只与一个核心网通过一条数据传输通道连接。
如图10所示，所述方法包括：
步骤1001至步骤1004，其与实施例三中的步骤801至步骤804相同，不再赘述。
步骤1005：基站接收目标核心网发送的切换请求确认消息，并向UE发送切换通知。
其中切换通知消息中包括：第四无线承载信息，和/或，第五无线承载信息。具体地，所述第四无线承载信息和第五无线承载信息的内容与前述实施例三相同，可参考实施例三中的描述，本实施例不再赘述。
步骤1006：UE向基站发送切换完成消息，该步骤用于UE通知基站已经完成切换。
步骤1007：基站与终端UE之间进行数据传输，所述数据传输包括上行数据和/或下行数据。
下行方向数据传输：
同实施例四。
上行方向数据传输：
UE通过第四无线承载信息中的无线承载向基站重新发送那些没有被基站确认正确接收的PDCP SDU；并且通过第五无线承载信息中的无线承载向基站发送上层新下来的数据包。
一种可能的实现方式中，为了保证基站按照数据包的顺序向上层提交数据，UE可以先在第四无线承载信息中的无线承载传输未成功发送的PDCP SDU，确认这些数据包被基站正确接收之后，再在第五无线承载信息中的无线承载上传输新的数据包。
另外一种可能实现方式是，UE在第四无线承载信息中的无线承载传输未成功发送的PDCP SDU，同时可以在第四无线承载信息中的无线承载中发送一个结束标识，例如，所述结束标识通过SDAP层或PDCP层或RLC层来指示，进一步地，可通过这些层包头中的比特来指示，或者通过这些层的某个不带净荷的PDU来指示，或者通过这些层的控制PDU来指示。
可选的，UE还可以同时在第五无线承载信息中的无线承载上传输新的数据包，即无需确认第五无线承载信息中的无线承载上传输的数据包被基站正确接收之后，就可以在第五无线承载信息中的无线承载上的传输新的数据包。
核心网切换之后，由于基站连接的核心网改为目标基站，所以基站从第四无线承载信息中的无线承载收到的数据需要特殊处理。一种处理方法与实施例二中的处理方法相同，仅需将实施例二中的第二无线承载信息替换为本实施例中的第四无线承载信息即可。
另外一种处理方法是，基站先接收第四无线承载信息中的无线承载中的数据，然后将所述第四无线承载信息中的无线承载的数据都提交给源核心网，然后再将第五无线承载信息中的无线承载的数据提交给目标核心网。基站将所述第四无线承载信息中的无线承载的数据都提交给源核心网完成之后，基站再向目标核心网发送切换完成消息。可选的，基站在第四无线承载信息中的无线承载上收到结束标识之后，基站再将第五无线承载信息中的无线承载的数据提交给目标核心网。
本方法中，由于基站仅有一套数据传输通道与源核心网或者目标核心网相连接，所以当UE切换前，基站通过该数据传输通道与源核心网进行数据传输；当核心网切换之后，基站再通过该数据传输通道与目标核心网建立连接，并进行数据传输。
步骤1008：基站向目标核心网发送切换完成消息。
该步骤同实施例二中的步骤512，本实施例不再赘述。
步骤1009：目标核心网与源核心网交互信息。
该步骤同实施例二中的步骤513，其主要用于目标核心网通知源核心网，UE已经切换并接入到了目标核心网。
步骤1010：源核心网向基站发送end marker包。
该步骤同实施例二中步骤514，参考前述实施例二中步骤514的描述，本实施例不再赘述。
下面介绍与上述各方法实施例对应的装置实施例。
参见图11，为本申请一实施例提供的一种数据传输装置，具体地，该数据传输装置为源基站，所述源基站110包括：接收单元1101、处理单元1102和发送单元1103，此外，还可以包括其它功能模块或单元，用于执行图3、图4、图5、图8和图10所对应的数据传输方法。
进一步地，处理单元1102，用于确定第一数据和用于承载所述第一数据的数据单元的无线空口协议序列号，所述第一数据包括：所述源基站与终端在数据传输过程中未被终端确认正确接收的数据。
发送单元1103，用于向目标基站发送所述第一数据和所述无线空口协议序列号。
其中，所述目标基站所连接的核心网与所述源基站所连接的核心网不同，所述源基站和所述目标基站为所述终端在不同核心网切换过程中的源基站和目标基站。
可选的，在本实施例的一种具体的实现方式中，处理单元1102，还用于确定第二数据，所述第二数据包括所述终端在核心网切换过程中，所述源基站从源核心网接收的待发送给所述终端的数据。发送单元1103，还用于向所述目标基站发送所述第二数据，以使所述目标基站对所述第二数据按照所述第一数据对应的无线空口协议序列号，继续分配所述第二数据的数据单元的无线空口协议序列号。
可选的，在本实施例的另一种具体的实现方式中，处理单元1102，还用于在所述源基站向目标基站发送所述第一数据和所述无线空口协议序列号之前，为所述终端配置第一无线承载信息，所述第一无线承载信息用于建立所述目标基站和所述终端之间的无线承载。发送单元1103，还用于向所述目标基站发送所述第一无线承载信息；接收单元1101，用于接收所述目标基站反馈的确认消息，所述确认消息用于指示所述目标基站和所述终端之间的第二无线承载信息。发送单元1103，还用于向所述终端发送所述第二无线承载信息。
可选的，在本实施例的又一种具体的实现方式中，所述确认消息还用于指示第三无线承载信息，所述第三无线承载信息用于配置第三数据的配置信息，所述第三无线承载信息为所述目标基站的目标核心网所接收的数据。
可选的，在本实施例的又一种具体的实现方式中，发送单元1103，具体用于通过第一隧道向所述目标基站发送所述第一数据中的所述未被终端确认正确接收的数据以及所述无线空口协议序列号。
可选的，在本实施例的又一种具体的实现方式中，所述第一数据还包括：所述源基站从终端接收的乱序的数据包，发送单元1103，具体用于通过第二隧道向所述目标基站发送所述第一数据中的来自所述终端的乱序的数据包以及与所述乱序的数据包对应的无线空口协议序列号。
参见图12，为本申请一实施例提供的一种数据传输装置，具体地，该数据传输装置为目标基站，所述目标基站120包括：接收单元1201、处理单元1202和发送单元1203，此外，还可以包括其它功能模块或单元，用于执行图5、图8和图10所对应的数据传输方法。
具体地，接收单元1201，用于接收来自源基站的第一数据和无线空口协议序列号，所述第一数据包括：所述源基站与终端在数据传输过程中未被终端确认正确接收的数据，所述无线空口协议序列号为所述源基站确定的用于承载所述第一数据的数据单元的序列号。发送单元1203，用于向所述终端发送所述第一数据和所述无线空口协议序列号。
其中，所述目标基站所连接的核心网与所述源基站所连接的核心网不同，所述源基站和所述目标基站为所述终端在不同核心网切换过程中的源基站和目标基站。
可选的，在本实施例的一种具体的实现方式中，接收单元1201，还用于接收来自所述源基站的第二数据，所述第二数据包括所述终端在核心网切换过程中，所述源基站从源核心网接收的待发送给所述终端的数据。处理单元1202，用于对所述第二数据按照所述第一数据对应的无线空口协议序列号，继续分配所述第二数据的数据单元的无线空口协议序列号。发送单元1203，还用于向所述终端发送所述第二数据和所述第二数据的数据单元的无线空口协议序列号。
可选的，在本实施例的又一种具体的实现方式中，接收单元1201，还用于在接收来自源基站的第一数据和无线空口协议序列号之前，接收来自源基站的第一无线承载信息，所述第一无线承载信息用于建立所述目标基站和所述终端之间的无线承载。处理单元1202，还用于根据所述第一无线承载信息确定第二无线承载信息，以及生成确认消息，所述确认消息用于指示所述目标基站和所述终端之间的所述第二无线承载信息。发送单元1203，还用于向所述源基站发送所述确认消息。
可选的，在本实施例的又一种具体的实现方式中，处理单元1202，还用于根据所述第一无线承载信息确定第三无线承载信息，所述第三无线承载信息包括目标基站所连接的目标核心网的配置信息。发送单元1203，还用于通过所述确认消息携带向所述源基站发送所述第三无线承载信息。
可选的，在本实施例的又一种具体的实现方式中，所述第二无线承载信息中包括第一无线承载，例如第一DRB；发送单元1203，具体用于通过所述第一无线承载向所述终端发送所述第二数据和所述第二数据的数据单元的无线空口协议序列号。
可选的，在本实施例的又一种具体的实现方式中，所述第二无线承载信息中包括第一无线承载，例如第一DRB；发送单元1203，具体用于通过所述第一无线承载向所述终端发送所述第二数据和所述第二数据的数据单元的无线空口协议序列号。
可选的，在本实施例的又一种具体的实现方式中，处理单元1202，还用于根据所述第三无线承载信息配置第二无线承载，例如第二DRB；发送单元1203，还用于将第三数据通过所述第二无线承载发送给所述终端，所述第三数据为位于所述目标基站的目标核心网所接收的数据。
参见图13，为本申请一实施例提供的一种数据传输装置，具体地，该数据传输装置为终端，所述终端130包括：接收单元1301、处理单元1302和发送单元1303，此外，还可以包括其它功能模块或单元，用于执行图5、图8和图10所对应的数据传输方法。
具体地，接收单元1301，用于接收来自目标基站的第一数据和无线空口协议序列号，所述第一数据包括：源基站与终端在数据传输过程中未被所述终端确认正确接收的数据，所述无线空口协议序列号为所述源基站确定的用于承载所述第一数据的数据单元的序列号。
处理单元1302，用于根据所述无线空口协议序列号对所述第一数据和缓存在终端的数据进行排序。
其中，所述目标基站所连接的核心网与所述源基站所连接的核心网不同，所述源基站和所述目标基站为所述终端在不同核心网切换过程中的源基站和目标基站。
可选的，在本实施例的一种具体的实现方式中，接收单元1301，还用于接收来自所述目标基站的第二数据和第二数据的数据单元的无线空口协议序列号，所述第二数据包括所述终端在核心网切换过程中，所述源基站从源核心网接收的待发送给所述终端的数据；处理单元1302，还用于按照所述第二数据和所述第二数据的数据单元的无线空口协议序列号对所述第二数据进行排序。
可选的，在本实施例的又一种具体的实现方式中，接收单元1301，还用于接收来自所述目标基站的第三数据和所述第三数据的数据单元的无线空口协议序列号，所述第三数据为从所述目标基站的目标核心网所接收的数据；处理单元1302，还用于按照所述第三数据 的数据单元的无线空口协议序列对所述第三数据进行排序。
可选的，在本实施例的又一种具体的实现方式中，接收单元1301，还用于在所述终端接收来自目标基站的第一数据和无线空口协议序列号之前，接收来自所述源基站的切换通知消息，所述切换通知可以为RRC重配消息，所述切换通知消息中包括接入到所述目标基站的目标小区ID。
处理单元1302，还用于根据所述目标小区ID接入到所述目标小区，并向所述目标基站发送切换完成消息。
可选的，在本实施例的又一种具体的实现方式中，所述切换通知消息中还包括第二无线承载信息，其中，所述第二无线承载信息中包括第一无线承载；例如第一DRB，用于传输带有SN号的未被UE确认的第一数据。
接收单元1301，具体用于利用所述第一无线承载接收所述第一数据和第一数据的数据单元的所述无线空口协议序列号。
可选的，在本实施例的又一种具体的实现方式中，所述切换通知消息中还包括第三无线承载信息，其中，所述第三无线承载信息中包括第二无线承载；第二DRB，用于传输切换后的数据包，即第三数据。
接收单元1301，具体用于用所述第二无线承载接收所述第三数据和第三数据的数据单元的无线空口协议序列号。
在具体的硬件实施例中，本申请还提供了一种网络设备，该网络设备可以是前述实施例中的基站、终端、核心网设备。其中，所述基站可以是连接到核心网EPC的LTE eNB，也可以是连接到5GC核心网的eLTE eNB，还可以是其它的源基站或者目标基站。
具体地，如图14所示，该网络设备包括收发器141、处理器142和存储器143，所述网络设备还可以包括更多或更少的部件，或者组合某些部件，或者不同的部件布置，本申请对此不进行限定。
收发器141用于数据或者消息的接收和发送，并与网络中的其他节点/设备进行数据传输。其中，收发器141可以包括收发模块，所述收发模块可以包括无线局域网(wireless local area network，WLAN)模块、蓝牙模块、基带(base band)模块等通信模块，以及所述通信模块对应的射频(radio frequency，RF)电路，用于进行无线局域网络通信、蓝牙通信、红外线通信及/或蜂窝式通信系统通信，例如宽带码分多重接入(wideband code division multiple access，WCDMA)及/或高速下行封包存取(high speed downlink packet access，HSDPA)。所述收发模块用于控制网络设备中的各组件的通信，并且可以支持直接内存存取(direct memory access)。
处理器142为网络设备的控制中心，利用各种接口和线路连接整个网络设备的各个部分，通过运行或执行存储在存储器143内的软件程序和/或模块，以及调用存储在存储器143内的数据，以执行网络设备的各种功能和/或处理数据。
进一步地，处理器142可以由集成电路(Integrated Circuit，IC)组成，例如可以由单颗封装的IC所组成，也可以由连接多颗相同功能或不同功能的封装IC而组成。举例来说，处理器可以仅包括中央处理器(Central Processing Unit，CPU)，也可以是GPU、数字信号处理器(Digital Signal Processor，DSP)、及收发器中的控制芯片(例如基带芯片)的组合。在本申请的各种实施方式中，CPU可以是单运算核心，也可以包括多运算 核心。
存储器143可以包括易失性存储器(volatile memory)，例如随机存取内存(Random Access Memory，RAM)；还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 Sisk 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。所述存储器中可以存储有程序或代码，处理器通过执行所述程序或代码可以实现所述网络设备的功能。
在本实施例中，收发器141所要实现的功能可以由前述各个装置实施例中的接收单元和发送单元来实现，或者由处理器142控制的收发器141实现；各个处理单元所要实现的功能则可以由处理器142实现。
此外，本申请还提供一种计算机存储介质，其中，该计算机存储介质可存储有程序，该程序执行时可包括本申请提供的设备升级方法的各实施例中的部分或全部步骤。所述的存储介质可为磁碟、光盘、只读存储记忆体ROM或随机存储记忆体RAM等。
在上述实施例中，可以全部或部分通过软件、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。
所述计算机程序产品包括一个或多个计算机指令，例如切换指令，在计算机加载和执行所述计算机程序时，全部或部分地产生按照本申请上述各个实施例所述的流程或功能。所述计算机可以是通用计算机、专用计算机、计算机网络或者其他可编程装置。
所述计算机指令可以存储在计算机可读存储介质中，或者从一个计算机可读存储介质向另一个计算机可读存储介质传输，例如，所述计算机指令可以从一个网络节点、计算机、服务器或数据中心通过有线或无线方式向另一个站点、计算机或服务器进行传输。
所述计算机可读存储介质可以是计算机能够存取的任何可用介质或者是包含一个或多个可用介质集成的服务器、数据中心等存储设备。所述可用介质可以是磁性介质，例如软盘、硬盘、磁带、光介质(例如DVD)、或半导体介质，例如固态硬盘SSD等。
另外，本申请实施例中所述的基站可以是GSM或CDMA中的基站(Base Transceiver Station，BTS)，也可以是WCDMA中的基站(NodeB)，还可以是LTE中的演进型基站(evolutional NodeB，eNB/e-NodeB),或者ng-eNB,或者gNB，本申请不予限定。
本申请各实施例中所述的终端，可以是指向用户提供语音和/或数据连通性的设备，具有无线连接功能的手持式设备、或连接到无线调制解调器的其他处理设备，例如无线终端。
所述无线终端可以经无线接入网RAN与一个或多个节点进行通信，所述无线终端可以是移动终端，如移动电话(或称为“蜂窝”电话)和具有移动终端的计算机，例如，可以是便携式、袖珍式、手持式、计算机内置的或者车载的移动装置，它们与无线接入网交换语言和/或数据。例如，个人通信业务(PCS，Personal Communication Service)电话、无绳电话、会话发起协议(SIP)话机、无线本地环路(WLL，Wireless Local Loop)站、个人数字助理(PDA，Personal Digital Assistant)等设备。无线终端也可以称为系统、订户单元(Subscriber Unit)、订户站(Subscriber Station)，移动站(Mobile Station)、移动台(Mobile)、远程站(Remote Station)、接入点(Access Point)、远程终端(Remote Terminal)、接入终端(Access Terminal)、用户终端(User Terminal)、用户代理(User Agent)、用户设备(User Device)、或用户装备(User Equipment)。
本申请的说明书和权利要求书及上述附图中的术语“第一”、“第二”等(如果存在)是用于区别类似的对象，而不必用于描述特定的顺序或先后次序。应该理解这样使用的数据在适当情况下可以互换，以便这里描述的实施例能够以除了在这里图示或描述的内容以外的顺序实施。此外，术语“包括”和“具有”以及他们的任何变形，意图在于覆盖不排他的包含，例如，包含了一系列步骤或单元的过程、方法、系统、产品或设备不必限于清楚地列出的那些步骤或单元，而是可包括没有清楚地列出的或对于这些过程、方法、产品或设备固有的其它步骤或单元。
本领域的技术人员可以清楚地了解到本申请实施例中的技术可借助软件加必需的通用硬件平台的方式来实现。基于这样的理解，本申请实施例中的技术方案本质上或者说对现有技术做出贡献的部分可以以软件产品的形式体现出来，该计算机软件产品可以存储在存储介质中，如ROM/RAM、磁碟、光盘等，包括若干指令用以使得一台计算机设备(可以是个人计算机，服务器，或者网络设备等)执行本发明各个实施例或者实施例的某些部分所述的方法。
本说明书中各个实施例之间相同相似的部分互相参见即可。尤其，对于网络设备/节点或装置设备而言，由于其基本相似于方法实施例，所以描述的比较简单，相关之处参见方法实施例中的说明即可。
以上所述的本申请实施方式并不构成对本申请保护范围的限定。

Claims (40)

  1. 一种数据传输方法，其特征在于，所述方法包括：
    源基站确定第一数据和用于承载所述第一数据的数据单元的无线空口协议序列号，所述第一数据包括：所述源基站与终端在数据传输过程中未被终端确认正确接收的数据；
    所述源基站向目标基站发送所述第一数据和所述无线空口协议序列号；
    其中，所述目标基站所连接的核心网与所述源基站所连接的核心网不同，所述源基站和所述目标基站为所述终端在不同核心网切换过程中的源基站和目标基站。
  2. 根据权利要求1所述的方法，其特征在于，所述方法还包括：
    所述源基站确定第二数据，所述第二数据包括：所述终端在核心网切换过程中，所述源基站从源核心网接收的待发送给所述终端的数据；
    所述源基站向所述目标基站发送所述第二数据，以使所述目标基站对所述第二数据按照所述第一数据对应的无线空口协议序列号，继续分配所述第二数据的数据单元的无线空口协议序列号。
  3. 根据权利要求1所述的方法，其特征在于，在所述源基站向目标基站发送所述第一数据和所述无线空口协议序列号之前，所述方法还包括：
    所述源基站为所述终端配置第一无线承载信息，所述第一无线承载信息用于建立所述源基站和所述终端之间的无线承载；
    所述源基站向所述目标基站发送所述第一无线承载信息；
    所述源基站接收所述目标基站反馈的确认消息，所述确认消息用于指示所述目标基站和所述终端之间的第二无线承载信息；
    所述源基站向所述终端发送所述第二无线承载信息。
  4. 根据权利要求3所述的方法，其特征在于，
    所述确认消息还用于指示第三无线承载信息，所述第三无线承载信息为用于配置第三数据的配置信息，所述第三数据为从所述目标基站的目标核心网所接收的数据。
  5. 根据权利要求1所述的方法，其特征在于，所述源基站向目标基站发送所述第一数据和所述无线空口协议序列号，包括：
    所述源基站通过第一隧道向所述目标基站发送所述第一数据中的所述未被终端确认正确接收的数据以及所述无线空口协议序列号。
  6. 根据权利要求1-5任一项所述的方法，其特征在于，所述第一数据还包括：所述源基站从终端接收的乱序的数据包，
    所述源基站向目标基站发送所述第一数据和所述无线空口协议序列号，包括：
    所述源基站通过第二隧道向所述目标基站发送所述第一数据中的来自所述终端的乱序的数据包以及与所述乱序的数据包对应的无线空口协议序列号。
  7. 一种数据传输方法，其特征在于，所述方法包括：
    目标基站接收来自源基站的第一数据和无线空口协议序列号，所述第一数据包括：所述源基站与终端在数据传输过程中未被终端确认正确接收的数据，所述无线空口协议序列号为所述源基站确定的用于承载所述第一数据的数据单元的序列号；
    所述目标基站向所述终端发送所述第一数据和所述无线空口协议序列号；
    其中，所述目标基站所连接的核心网与所述源基站所连接的核心网不同，所述源基站 和所述目标基站为所述终端在不同核心网切换过程中的源基站和目标基站。
  8. 根据权利要求7所述的方法，其特征在于，所述方法还包括：
    所述目标基站接收来自所述源基站的第二数据，所述第二数据包括所述终端在核心网切换过程中，所述源基站从源核心网接收的待发送给所述终端的数据；
    所述目标基站对所述第二数据按照所述第一数据对应的无线空口协议序列号，继续分配所述第二数据的数据单元的无线空口协议序列号；
    所述目标基站向所述终端发送所述第二数据和所述第二数据的数据单元的无线空口协议序列号。
  9. 根据权利要求7所述的方法，其特征在于，所述目标基站接收来自源基站的第一数据和无线空口协议序列号之前，所述方法还包括：
    所述目标基站接收来自源基站的第一无线承载信息，所述第一无线承载信息用于建立所述目标基站和所述终端之间的无线承载；
    所述目标基站根据所述第一无线承载信息确定第二无线承载信息，以及生成确认消息，所述确认消息用于指示所述目标基站和所述终端之间的所述第二无线承载信息；
    所述目标基站向所述源基站发送所述确认消息。
  10. 根据权利要求9所述的方法，其特征在于，所述方法还包括：
    所述目标基站根据所述第一无线承载信息确定第三无线承载信息，所述第三无线承载信息包括目标基站所连接的目标核心网的配置信息；
    所述目标基站通过所述确认消息携带向所述源基站发送所述第三无线承载信息。
  11. 根据权利要求9所述的方法，其特征在于，所述第二无线承载信息中包括第一无线承载；
    所述目标基站向所述终端发送所述第一数据和所述无线空口协议序列号，包括：
    所述目标基站通过所述第一无线承载向所述终端发送所述第二数据和所述第二数据的数据单元的无线空口协议序列号。
  12. 根据权利要求8所述的方法，其特征在于，所述第二无线承载信息中包括第一无线承载；
    所述目标基站向所述终端发送所述第二数据和所述第二数据的数据单元的无线空口协议序列号，包括：
    所述目标基站通过所述第一无线承载向所述终端发送所述第二数据和所述第二数据的数据单元的无线空口协议序列号。
  13. 根据权利要求10所述的方法，其特征在于，所述方法还包括：
    所述目标基站根据所述第三无线承载信息配置第二无线承载；
    所述目标基站将第三数据通过所述第二无线承载发送给所述终端，所述第三数据为位于所述目标基站的目标核心网所接收的数据。
  14. 一种数据传输方法，其特征在于，所述方法包括：
    终端接收来自目标基站的第一数据和无线空口协议序列号，所述第一数据包括：源基站与终端在数据传输过程中未被所述终端确认正确接收的数据，所述无线空口协议序列号为所述源基站确定的用于承载所述第一数据的数据单元的序列号；
    所述终端根据所述无线空口协议序列号对所述第一数据和缓存在终端的数据进行排 序；
    其中，所述目标基站所连接的核心网与所述源基站所连接的核心网不同，所述源基站和所述目标基站为所述终端在不同核心网切换过程中的源基站和目标基站。
  15. 根据权利要求14所述的方法，其特征在于，所述方法还包括：
    所述终端接收来自所述目标基站的第二数据和第二数据的数据单元的无线空口协议序列号，所述第二数据包括：所述终端在核心网切换过程中，所述源基站从源核心网接收的待发送给所述终端的数据；
    所述终端按照所述第二数据的数据单元的无线空口协议序列号对所述第二数据进行排序。
  16. 根据权利要求14所述的方法，其特征在于，所述方法还包括：
    所述终端接收来自所述目标基站的第三数据和所述第三数据的数据单元的无线空口协议序列号，所述第三数据为从所述目标基站的目标核心网所接收的数据；
    所述终端按照所述第三数据的数据单元的无线空口协议序列号对所述第三数据进行排序。
  17. 根据权利要求14-16任一项所述的方法，其特征在于，在所述终端接收来自目标基站的第一数据和无线空口协议序列号之前，所述方法还包括：
    所述终端接收来自所述源基站的切换通知消息，所述切换通知消息中包括接入到所述目标基站的目标小区ID；
    所述终端根据所述目标小区ID接入到所述目标小区，并向所述目标基站发送切换完成消息。
  18. 根据权利要求17所述的方法，其特征在于，所述切换通知消息中还包括第二无线承载信息，其中，所述第二无线承载信息中包括第一无线承载；
    所述终端接收来自目标基站的第一数据和无线空口协议序列号，包括；
    所述终端利用所述第一无线承载接收所述第一数据和第一数据的数据单元的所述无线空口协议序列号。
  19. 根据权利要求16所述的方法，其特征在于，所述切换通知消息中还包括第三无线承载信息，其中，所述第三无线承载信息中包括第二无线承载；
    所述终端接收来自所述目标基站的第三数据，包括：
    所述终端利用所述第二无线承载接收所述第三数据和第三数据的数据单元的无线空口协议序列号。
  20. 一种数据传输装置，其特征在于，所述装置应用于源基站中，所述装置包括：
    处理单元，用于确定第一数据和用于承载所述第一数据的数据单元的无线空口协议序列号，所述第一数据包括：所述源基站与终端在数据传输过程中未被终端确认正确接收的数据；
    发送单元，用于向目标基站发送所述第一数据和所述无线空口协议序列号；
    其中，所述目标基站所连接的核心网与所述源基站所连接的核心网不同，所述源基站和所述目标基站为所述终端在不同核心网切换过程中的源基站和目标基站。
  21. 根据权利要求20所述的装置，其特征在于，
    所述处理单元，还用于确定第二数据，所述第二数据包括所述终端在核心网切换过程 中，所述源基站从源核心网接收的待发送给所述终端的数据；
    所述发送单元，还用于向所述目标基站发送所述第二数据，以使所述目标基站对所述第二数据按照所述第一数据对应的无线空口协议序列号，继续分配所述第二数据的数据单元的无线空口协议序列号。
  22. 根据权利要求20所述的装置，其特征在于，还包括：接收单元，
    所述处理单元，还用于在所述源基站向目标基站发送所述第一数据和所述无线空口协议序列号之前，为所述终端配置第一无线承载信息，所述第一无线承载信息用于建立所述目标基站和所述终端之间的无线承载；
    所述发送单元，还用于向所述目标基站发送所述第一无线承载信息；
    所述接收单元，用于接收所述目标基站反馈的确认消息，所述确认消息用于指示所述目标基站和所述终端之间的第二无线承载信息；
    所述发送单元，还用于向所述终端发送所述第二无线承载信息。
  23. 根据权利要求22所述的装置，其特征在于，
    所述确认消息还用于指示第三无线承载信息，所述第三无线承载信息用于配置第三数据的配置信息，所述第三无线承载信息为所述目标基站的目标核心网所接收的数据。
  24. 根据权利要求20所述的装置，其特征在于，
    所述发送单元，具体用于通过第一隧道向所述目标基站发送所述第一数据中的所述未被终端确认正确接收的数据以及所述无线空口协议序列号。
  25. 根据权利要求20-24任一项所述的装置，其特征在于，所述第一数据还包括：所述源基站从终端接收的乱序的数据包，
    所述发送单元，具体用于通过第二隧道向所述目标基站发送所述第一数据中的来自所述终端的乱序的数据包以及与所述乱序的数据包对应的无线空口协议序列号。
  26. 一种数据传输装置，其特征在于，所述装置应用于目标基站，所述装置包括：
    接收单元，用于接收来自源基站的第一数据和无线空口协议序列号，所述第一数据包括：所述源基站与终端在数据传输过程中未被终端确认正确接收的数据，所述无线空口协议序列号为所述源基站确定的用于承载所述第一数据的数据单元的序列号；
    发送单元，用于向所述终端发送所述第一数据和所述无线空口协议序列号；
    其中，所述目标基站所连接的核心网与所述源基站所连接的核心网不同，所述源基站和所述目标基站为所述终端在不同核心网切换过程中的源基站和目标基站。
  27. 根据权利要求26所述的装置，其特征在于，还包括处理单元，
    所述接收单元，还用于接收来自所述源基站的第二数据，所述第二数据包括所述终端在核心网切换过程中，所述源基站从源核心网接收的待发送给所述终端的数据；
    所述处理单元，用于对所述第二数据按照所述第一数据对应的无线空口协议序列号，继续分配所述第二数据的数据单元的无线空口协议序列号；
    所述发送单元，还用于向所述终端发送所述第二数据和所述第二数据的数据单元的无线空口协议序列号。
  28. 根据权利要求26所述的装置，其特征在于，
    所述接收单元，还用于在接收来自源基站的第一数据和无线空口协议序列号之前，接收来自源基站的第一无线承载信息，所述第一无线承载信息用于建立所述目标基站和所述 终端之间的无线承载；
    所述处理单元，还用于根据所述第一无线承载信息确定第二无线承载信息，以及生成确认消息，所述确认消息用于指示所述目标基站和所述终端之间的所述第二无线承载信息；
    所述发送单元，还用于向所述源基站发送所述确认消息。
  29. 根据权利要求28所述的装置，其特征在于，
    所述处理单元，还用于根据所述第一无线承载信息确定第三无线承载信息，所述第三无线承载信息包括目标基站所连接的目标核心网的配置信息；
    所述发送单元，还用于通过所述确认消息携带向所述源基站发送所述第三无线承载信息。
  30. 根据权利要求28所述的装置，其特征在于，所述第二无线承载信息中包括第一无线承载；
    所述发送单元，具体用于通过所述第一无线承载向所述终端发送所述第二数据和所述第二数据的数据单元的无线空口协议序列号。
  31. 根据权利要求27所述的装置，其特征在于，所述第二无线承载信息中包括第一无线承载；
    所述发送单元，具体用于通过所述第一无线承载向所述终端发送所述第二数据和所述第二数据的数据单元的无线空口协议序列号。
  32. 根据权利要求29所述的装置，其特征在于，
    所述处理单元，还用于根据所述第三无线承载信息配置第二无线承载；
    所述发送单元，还用于将第三数据通过所述第二无线承载发送给所述终端，所述第三数据为位于所述目标基站的目标核心网所接收的数据。
  33. 一种终端，其特征在于，所述终端包括：
    接收单元，用于接收来自目标基站的第一数据和无线空口协议序列号，所述第一数据包括：源基站与终端在数据传输过程中未被所述终端确认正确接收的数据，所述无线空口协议序列号为所述源基站确定的用于承载所述第一数据的数据单元的序列号；
    处理单元，用于根据所述无线空口协议序列号对所述第一数据和缓存在终端的数据进行排序；
    其中，所述目标基站所连接的核心网与所述源基站所连接的核心网不同，所述源基站和所述目标基站为所述终端在不同核心网切换过程中的源基站和目标基站。
  34. 根据权利要求33所述的终端，其特征在于，
    所述接收单元，还用于接收来自所述目标基站的第二数据和第二数据的数据单元的无线空口协议序列号，所述第二数据包括所述终端在核心网切换过程中，所述源基站从源核心网接收的待发送给所述终端的数据；
    所述处理单元，还用于按照所述第二数据和所述第二数据的数据单元的无线空口协议序列号对所述第二数据进行排序。
  35. 根据权利要求33所述的终端，其特征在于，
    所述接收单元，还用于接收来自所述目标基站的第三数据和所述第三数据的数据单元的无线空口协议序列号，所述第三数据为从所述目标基站的目标核心网所接收的数据；
    所述处理单元，还用于按照所述第三数据的数据单元的无线空口协议序列对所述第三数据进行排序。
  36. 根据权利要求33-35任一项所述的终端，其特征在于，
    所述接收单元，还用于在所述终端接收来自目标基站的第一数据和无线空口协议序列号之前，接收来自所述源基站的切换通知消息，所述切换通知消息中包括接入到所述目标基站的目标小区ID；
    所述处理单元，还用于根据所述目标小区ID接入到所述目标小区，并向所述目标基站发送切换完成消息。
  37. 根据权利要求36所述的终端，其特征在于，所述切换通知消息中还包括第二无线承载信息，其中，所述第二无线承载信息中包括第一无线承载；
    所述接收单元，具体用于利用所述第一无线承载接收所述第一数据和第一数据的数据单元的所述无线空口协议序列号。
  38. 根据权利要求35所述的终端，其特征在于，所述切换通知消息中还包括第三无线承载信息，其中，所述第三无线承载信息中包括第二无线承载；
    所述接收单元，具体用于用所述第二无线承载接收所述第三数据和第三数据的数据单元的无线空口协议序列号。
  39. 一种计算机可读存储介质，所述存储介质中存储有指令，其特征在于，
    当所述指令被运行时，实现如权利要求1至6、7至13、或14至19中任一项所述的方法。
  40. 一种数据传输系统，其特征在于，所述系统中包括至少一个基站和至少一个终端，所述至少一个基站包括源基站和目标基站，
    所述源基站为如权利要求20至25任一项所述的装置；
    所述目标基站为如权利要求26至32任一项所述的装置；
    所述终端为如权利要求33至38任一项所述的终端。
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