WO2020168720A1 - 通信方法和通信装置 - Google Patents

通信方法和通信装置 Download PDF

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Publication number
WO2020168720A1
WO2020168720A1 PCT/CN2019/109136 CN2019109136W WO2020168720A1 WO 2020168720 A1 WO2020168720 A1 WO 2020168720A1 CN 2019109136 W CN2019109136 W CN 2019109136W WO 2020168720 A1 WO2020168720 A1 WO 2020168720A1
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WIPO (PCT)
Prior art keywords
data channel
information
terminal device
network element
management network
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PCT/CN2019/109136
Other languages
English (en)
French (fr)
Inventor
景昊
宗在峰
朱奋勤
施拉姆·米而科
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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Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Priority to EP19877542.1A priority Critical patent/EP3731563B1/en
Priority to CN201980085075.5A priority patent/CN113455047A/zh
Priority to BR112021010548-4A priority patent/BR112021010548A2/pt
Priority to JP2021518100A priority patent/JP7088451B2/ja
Priority to US16/845,026 priority patent/US11134371B2/en
Publication of WO2020168720A1 publication Critical patent/WO2020168720A1/zh
Priority to US17/468,157 priority patent/US11849505B2/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W8/00—Network data management
    • H04W8/02—Processing of mobility data, e.g. registration information at HLR [Home Location Register] or VLR [Visitor Location Register]; Transfer of mobility data, e.g. between HLR, VLR or external networks
    • H04W8/08—Mobility data transfer
    • 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
    • H04W36/0033—Control or signalling for completing the hand-off for data sessions of end-to-end connection with transfer of context information
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L67/00—Network arrangements or protocols for supporting network services or applications
    • H04L67/14—Session management
    • H04L67/142—Managing session states for stateless protocols; Signalling session states; State transitions; Keeping-state mechanisms
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L67/00—Network arrangements or protocols for supporting network services or applications
    • H04L67/50—Network services
    • H04L67/56—Provisioning of proxy services
    • H04L67/564—Enhancement of application control based on intercepted application data
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/02—Traffic management, e.g. flow control or congestion control
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/02—Traffic management, e.g. flow control or congestion control
    • H04W28/0268—Traffic management, e.g. flow control or congestion control using specific QoS parameters for wireless networks, e.g. QoS class identifier [QCI] or guaranteed bit rate [GBR]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • 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
    • H04W36/0033—Control or signalling for completing the hand-off for data sessions of end-to-end connection with transfer of context information
    • H04W36/0044—Control or signalling for completing the hand-off for data sessions of end-to-end connection with transfer of context information of quality context information
    • 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
    • H04W48/00—Access restriction; Network selection; Access point selection
    • H04W48/16—Discovering, processing access restriction or access information
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W48/00—Access restriction; Network selection; Access point selection
    • H04W48/18—Selecting a network or a communication service
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W56/00—Synchronisation arrangements
    • H04W56/001—Synchronization between nodes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W60/00—Affiliation to network, e.g. registration; Terminating affiliation with the network, e.g. de-registration
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W80/00—Wireless network protocols or protocol adaptations to wireless operation
    • H04W80/08—Upper layer protocols
    • H04W80/10—Upper layer protocols adapted for application session management, e.g. SIP [Session Initiation Protocol]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/16—Central resource management; Negotiation of resources or communication parameters, e.g. negotiating bandwidth or QoS [Quality of Service]
    • H04W28/24—Negotiating SLA [Service Level Agreement]; Negotiating QoS [Quality of Service]

Definitions

  • This application relates to the field of communication, and in particular to a communication method and communication device.
  • the core network elements and terminal equipment may need to be switched from the 4G communication system to the 5G communication system , It may also be necessary to switch from a 5G communication system to a 4G communication system. Since the terminal device and the core network element cannot always maintain normal communication, for example, the terminal device is in an idle state or cannot receive the message sent by the core network element when a communication failure occurs. Therefore, the terminal device and the core network device are switching communication A communication failure may occur after the system. How to improve the reliability of the communication system when switching is a problem that needs to be solved urgently.
  • This application provides a communication method, which can be applied to a scenario where a 4G communication system and a 5G communication system coexist.
  • the communication device using this method determines the data channel that needs to be synchronized in the communication system switching process and performs synchronization processing, so that the data channel information saved by each communication device after the communication system is switched is consistent, thereby avoiding the communication failure after the communication system is switched. Case.
  • a communication method including: a session management network element determines a first data channel in a first system, where the first data channel is a data channel to be synchronized with a terminal device; In the process of switching the first system to the second system, at least one of the following is synchronized: the first data channel, or, the second data channel corresponding to the first data channel in the second system.
  • the first data channel is a data channel that the terminal device has deleted but has not notified the network side.
  • the session management network element may determine the data channel that needs to be synchronized with the terminal device before the communication system is switched, and may also determine the data channel that needs to be synchronized with the terminal device during the communication system switching process. Subsequently, the session management network element performs synchronization processing in the communication system switching process, deletes the locally stored information of the first data channel and/or the second data channel, or instructs the terminal device to delete the first data channel and/or the second data channel. The information of the data channel completes the synchronization processing of the data channel.
  • the above solution makes the data channel information saved by each communication device consistent after the communication system is switched, and avoids the possibility of communication failure after the communication system is switched.
  • the session management network element determining the first data channel in the first system includes: the session management network element receives the first state information, and the first state information is used to indicate the status of the data channel in the terminal device Status; the session management network element determines the first data channel according to the first status information.
  • the session management network element may compare the data channel information stored locally with the data channel information stored by the terminal device indicated by the first status information, and the data channel corresponding to the inconsistent information in the two data channel information is the first data channel. Since the data channel information stored by other core network elements is information obtained from the session management network element and may not be updated in time, the above solution can avoid possible errors in determining the data channel to be synchronized by other core network elements.
  • the session management network element determines the first data channel in the first system, including: the session management network element sends a protocol configuration option PCO to the terminal device; when the session management network element receives a PCO that does not carry the PCO In response to the message, the session management network element determines the first data channel.
  • PCO is dedicated information between the session management network element and the terminal device. Other network elements only transparently transmit the PCO. Therefore, if the session management network element does not receive a response message containing the PCO, it means that the session management network element and the terminal device The data channel deleted by the session management network element may not be deleted on the terminal device side. Therefore, the session management network element may determine the first data channel according to the above solution. Since the above solution does not add new information, it is determined that the first data channel can be better compatible with the existing technology by applying this solution.
  • the PCO includes at least one of the information of the first data channel or the information of the second data channel.
  • the session management network element can also clearly indicate the data channel that the terminal device needs to synchronize through the PCO, and other core network elements only need to transparently transmit the PCO without analyzing the PCO, thereby reducing the load of other core network elements.
  • the session management network element determining the first data channel in the first system includes: the session management network element sends a first message to the mobility management network element in the first system, and the first message uses Instructing to delete one or more data channels; the session management network element receives a second message from the mobility management network element in the first system, the second message is used to indicate that the first message has not been notified to the terminal device; the session management network element The one or more data channels are determined as the first data channel according to the second message.
  • the session management network element synchronizes at least one of the following in the process of the terminal device switching from the first system to the second system: the first data channel, or the second system and the second system A second data channel corresponding to a data channel; including:
  • the session management network element triggers a session modification process, and the session modification process is used to synchronize at least one of the following: the first data channel, or, the second data channel corresponding to the first data channel in the second system; or,
  • the session management network element triggers synchronization of at least one of the following during the protocol data unit PDU session activation process or the PDN connection activation process: the first data channel, or the second data corresponding to the first data channel in the second system aisle.
  • the above solution provides a variety of optional methods for the synchronization processing of the session management network elements, and has high flexibility.
  • the session management network element synchronizes at least one of the following in the process of the terminal device switching from the first system to the second system: the first data channel, or the second system and the first system The second data channel corresponding to the data channel; including: the session management network element deletes at least one of the information of the first data channel or the information of the second data channel;
  • the information of the first data channel includes information carried by the EPS bearer of the evolved packet system
  • the information of the second data channel includes information about the QoS flow associated with the EPS bearer.
  • the information of the first data channel includes QoS flow information
  • the information of the second data channel includes EPS bearer information associated with the QoS flow.
  • the present application also provides a communication method, including: the mobility management network element in the second system determines the first data channel in the first system, and the first data channel is data to be synchronized with the terminal device Channel; the mobility management management network element in the second system synchronizes at least one of the following in the process of the terminal device switching from the first system to the second system: the first data channel, or, the second system and the first The second data channel corresponding to the data channel.
  • the mobility management network element in the second system is a mobility management network element that communicates with the terminal device after the communication system is switched.
  • the mobility management network element in the second system determines the data channel that needs to be synchronized with the terminal device. Subsequently, the mobility management network element performs synchronization processing to delete the locally stored information of the first data channel and/or the second data channel, or instruct the terminal device to delete the information of the first data channel and/or the second data channel, Complete the synchronization processing of the data channel.
  • the above solution makes the data channel information saved by each communication device consistent after the communication system is switched, and avoids the possibility of communication failure after the communication system is switched.
  • the mobility management network element in the second system determines the first data channel in the first system, including: the mobility management network element in the second system receives the first state information from the terminal device , The first status information is used to indicate the status of the data channel of the terminal device; the mobility management network element in the second system receives the second status information from the mobility management network element in the first system, and the second status information is used to indicate The state of the data channel of the terminal device; the mobility management network element in the second system determines the first data channel according to the first state information and the second state information.
  • the reason for the unsynchronization of the data channel may be a problem in the information interaction process of deleting the data channel between the terminal device and the core network element in the original communication system (ie, the first system). Therefore, the mobility management network in the second system The element can compare the data channel information stored by the mobility management network element in the first system with the data channel information stored by the terminal device, and the data channel corresponding to the inconsistent information in the two data channel information is the first data channel.
  • the foregoing solution does not require the implementation of the session management network element, which reduces the burden of the session management network element.
  • the method further includes: the mobility management network element in the second system sends first state information to the session management network element, and the first state information is used for determining the first data channel.
  • the mobility management network element in the second system may also send the first status information to the session management network element, so that the session management network element can compare the data channel information stored in the session management network element with the data channel information stored in the terminal device.
  • the data channel corresponding to the inconsistent information in the two data channel information is the first data channel. Since the data channel information stored by other core network elements is information obtained from the session management network element and may not be updated in time, the above solution can avoid possible errors in determining the data channel to be synchronized by other core network elements.
  • the present application also provides a communication method, including: the terminal device determines the first data channel in the first system, the first data channel is the data channel to be synchronized with the session management network element; The process of switching a system to the second system synchronizes at least one of the following: a first data channel, or a second data channel corresponding to the first data channel in the second system.
  • the terminal device may determine the data channel that needs to be synchronized with the session management network element before the communication system is switched, and may also determine the data channel that needs to be synchronized with the session management network element during the communication system switching process. Subsequently, the terminal device performs synchronization processing in the communication system switching process to delete the locally stored information of the first data channel and/or the second data channel, or notify the session management network element to delete the first data channel and/or the second data channel. The information of the data channel completes the synchronization processing of the data channel.
  • the above solution makes the data channel information saved by each communication device consistent after the communication system is switched, and avoids the possibility of communication failure after the communication system is switched.
  • the terminal device determining the first data channel in the first system includes: the terminal device sends a notification message to the session management network element, and the notification message is used to notify the session management network element that the terminal device deletes a Or multiple data channels; the terminal device determines the one or more data channels as the first data channel according to the response message of not receiving the notification message.
  • the terminal device can initiate the process of deleting the data channel. If the terminal device does not receive the response message of the communication message, it means that there is a problem in the communication between the terminal device and the session management network element, and the terminal device is ready to delete or the deleted data channel has not been deleted.
  • the terminal device may determine that the data channel to be deleted or deleted is the data channel to be synchronized, that is, the first data channel.
  • the method further includes: the terminal device sends first state information to the session management network element, the first state information indicates the state of the data channel in the terminal device, and the first state information is used for the first state information. Determination of the data channel.
  • the terminal device may not receive the message to delete the data channel sent by the session management network element because it is in the idle state.
  • the terminal device may actively send the first status information to the session management network element, or the terminal device may follow the request of the core network element
  • the first status information is sent to facilitate the session management network element to determine whether the data channel needs to be synchronized.
  • the terminal device determining the first data channel in the first system includes: the terminal device sends the first PCO to the session management network element; when the terminal device receives a response message that does not carry the first PCO, the terminal device Determine the first data channel.
  • the PCO is the dedicated information between the session management network element and the terminal device. Other network elements only transparently transmit the PCO. Therefore, if the session management network element does not receive a response message containing the first PCO, it means that the session management network element and the terminal device There is a problem with the communication between them, and the data channel deleted by the session management network element may not be deleted on the terminal device side. Therefore, the session management network element may determine the first data channel according to the above solution. Since the above solution does not add new information, it is determined that the first data channel can be better compatible with the existing technology by applying this solution.
  • the first PCO includes at least one of the information of the first data channel or the information of the second data channel.
  • the terminal device can also clearly notify the session management network element of the data channel that needs to be synchronized through the first PCO, and other core network elements only need to transparently transmit the first PCO without analyzing the first PCO, thereby reducing the load of other core network elements .
  • the terminal device determining the first data channel in the first system includes: the terminal device receives second state information, the second state information is used to indicate the state of the data channel in the session management network element; The status information determines the first data channel.
  • the terminal device can also compare the locally stored data channel information with the data channel information stored by the session management network element indicated by the second state information.
  • the data channel corresponding to the inconsistent information in the two data channel information is the first data. aisle. Since the data channel information saved by the mobility management network element is information obtained from the terminal device or the session management network element, and may not be updated in time, the above solution can prevent the mobility management network element from determining the data channel to be synchronized may appear mistake.
  • the terminal device synchronizes at least one of the following in the process of switching from the first system to the second system: the first data channel, or the second system corresponding to the first data channel The second data channel; including: the terminal device deletes at least one of the information of the first data channel or the information of the second data channel;
  • the information of the first data channel includes information of the EPS bearer
  • the information of the second data channel includes information of the QoS flow associated with the EPS bearer
  • the information of the first data channel includes QoS flow information
  • the information of the second data channel includes EPS bearer information associated with the QoS flow.
  • the response message of the PCO is used to indicate that the terminal device has deleted the data channel to be deleted, or the response message of the PCO is used to indicate that the terminal device has determined to delete the data channel to be deleted Or, the response message of the PCO is used to indicate that the terminal device has received the PCO message.
  • the terminal device receives the PCO from the session management network element; the terminal device sends the PCO response message to the session management network element, and the PCO response message does not include any parameters, or,
  • the PCO includes at least one of the information of the first data channel or the information of the second data channel.
  • PCO is the dedicated information between the session management network element and the terminal device. Other network elements only transparently transmit the PCO. Therefore, the PCO determines the data channel to be deleted between the terminal device and the session management network element, which is beneficial to improve the synchronization data channel. effectiveness.
  • the response message of the PCO is used to indicate that the terminal device has deleted the data channel to be deleted, or the response message of the PCO is used to indicate that the terminal device has determined to delete the data channel to be deleted Or, the response message of the PCO is used to indicate that the terminal device has received the PCO message.
  • the present application also provides a communication method, including: the terminal device determines that the terminal device has been deleted in the first system but does not notify the first data channel on the network side; the terminal device sends the session management network element Sending first status information, the first status information indicating the status of the data channel in the terminal device, and the first status information is used for determining the first data channel.
  • the terminal device sends a first message to the mobility management network element, and the first message includes the first status information, where the first message is an attachment request message, a registration request message, or a session establishment Request message.
  • this application also provides a communication method, including: a session management network element deletes a first data channel in a first system, where the first data channel is a data channel to be synchronized with a terminal device; the session The management network element sends the data channel information to the mobility management network element in the second system, where the data channel information includes the identification information of the data channel, or is between the identification information of the data channel and the allocation and reservation priority (For example, refer to the description of step 1209 in FIG. 12).
  • the above solution makes the data channel information saved by each communication device consistent after the communication system is switched, and avoids the possibility of communication failure after the communication system is switched.
  • the present application also provides a communication method, including: the mobility management network element in the second system receives data channel information from the session management network element, wherein the data channel information includes an identifier of the data channel Information, or the correspondence between the identification information of the data channel and the allocation and reservation priority (for example, refer to the description of step 1209 in FIG.
  • the mobility management network element determines the status according to the information of the data channel Information (for example, refer to the description of step 1210 in Figure 12); the mobility management network element sends the status information to the terminal device (for example, refer to the description of steps 1211 to 1213 in Figure 12), the The status information is used for the synchronization of the terminal device side with respect to at least one of the following: the first data channel, or the second data channel corresponding to the first data channel in the second system.
  • the first data channel is a data channel to be synchronized with the terminal device.
  • this application also provides a communication method, including: a terminal device receives status information from a mobility management network element in a second system (for example, refer to the description of steps 1211 and 1212 in FIG. 12); The terminal device determines a first data channel according to the status information, where the first data channel is a data channel to be synchronized with the terminal device; the terminal device synchronizes at least one of the following: the first data channel, or, The second data channel corresponding to the first data channel in the second system (for example, refer to the description of step 1213 in FIG. 12).
  • the terminal device deletes at least one of the information of the first data channel or the information of the second data channel; wherein, when the first system is a 4G system, the second system is a 5G system, so The information of the first data channel includes the information carried by the EPS of the evolved packet system, and the information of the second data channel includes the information of the QoS flow associated with the EPS bearer; or when the first system is a 5G system, The second system is a 4G system, the information of the first data channel includes QoS flow information, and the information of the second data channel includes EPS bearer information associated with the QoS flow.
  • the above solution makes the data channel information saved by each communication device consistent after the communication system is switched, and avoids the possibility of communication failure after the communication system is switched.
  • the present application provides a communication device.
  • the communication device may be a session management network element or a chip in the session management network element.
  • the communication device may include a processing unit and a transceiving unit.
  • the processing unit may be a processor, and the transceiver unit may be a communication interface;
  • the session management network element may also include a storage unit, and the storage unit may be a memory; the storage unit is used for storing Instruction, the processing unit executes the instruction stored in the storage unit, so that the session management network element executes the method described in the first aspect or the fifth aspect.
  • the processing unit can be a processor, and the transceiver unit can be an input/output interface, a pin or a circuit, etc.; the processing unit executes the instructions stored in the storage unit to make
  • the session management network element executes the method described in the first aspect or the fifth aspect, and the storage unit may be a storage unit (for example, a register, a cache, etc.) in the chip, or may be a storage unit located in the session management network element.
  • a storage unit outside the chip for example, read-only memory, random access memory, etc.).
  • this application provides another communication device, which may be a mobility management network element or a chip in the mobility management network element.
  • the device may include a processing unit and a transceiving unit.
  • the processing unit may be a processor, and the transceiving unit may be a communication interface;
  • the mobility management network element may also include a storage unit, and the storage unit may be a memory;
  • the processing unit executes the instructions stored in the storage unit, so that the mobility management network element executes the method described in the second aspect or the sixth aspect.
  • the processing unit can be a processor, and the transceiver unit can be an input/output interface, a pin or a circuit, etc.; the processing unit executes the instructions stored in the storage unit to To cause the mobility management network element to execute the method described in the second or sixth aspect, the storage unit may be a storage unit (for example, a register, a cache, etc.) in the chip, or may be in the mobility management network element The storage unit (for example, read only memory, random access memory, etc.) located outside the chip.
  • this application provides yet another communication device, which may be a terminal device or a chip in the terminal device.
  • the device may include a processing unit and a transceiving unit.
  • the processing unit may be a processor, and the transceiving unit may be a transceiver;
  • the terminal device may also include a storage unit, and the storage unit may be a memory; the storage unit is used to store instructions, and the processing The unit executes the instructions stored in the storage unit, so that the terminal device executes the method described in the third aspect, the fourth aspect, or the seventh aspect.
  • the processing unit may be a processor, and the transceiver unit may be an input/output interface, a pin or a circuit, etc.; the processing unit executes the instructions stored in the storage unit to make the terminal
  • the device executes the method described in the third aspect, the fourth aspect, or the seventh aspect.
  • the storage unit may be a storage unit (for example, a register, a cache, etc.) in the chip, or may be a storage unit in the terminal device located outside the chip.
  • the storage unit for example, read only memory, random access memory, etc.).
  • the present application provides a computer-readable storage medium that stores a computer program in the computer-readable storage medium.
  • the processor executes the first aspect or the fifth aspect. The method described.
  • the present application provides a computer-readable storage medium that stores a computer program in the computer-readable storage medium.
  • the processor executes the second or sixth aspects. The method described.
  • the present application provides a computer-readable storage medium that stores a computer program in the computer-readable storage medium.
  • the processor executes the third, fourth, or The method described in the seventh aspect.
  • the present application provides a computer program product, the computer program product includes: computer program code, when the computer program code is run by a processor, the processor executes the first aspect or the fifth aspect method.
  • this application provides a computer program product, the computer program product comprising: computer program code, when the computer program code is executed by a processor, the processor executes the second aspect or the sixth aspect method.
  • this application provides a computer program product, the computer program product comprising: computer program code, when the computer program code is executed by a processor, the processor executes the third aspect, the fourth aspect or the seventh aspect The method described in the aspect.
  • the present application also provides a communication method, including: the session management network element sends a deletion message and a PCO to the terminal device, the deletion message is used to indicate the data channel to be deleted; the session management network element is based on It is determined that the terminal device has deleted the data channel to be deleted after receiving the response message of the PCO, or it is determined that the terminal device has deleted the data channel to be deleted, or it is determined that the terminal device has received it. To the delete message.
  • PCO is the dedicated information between the session management network element and the terminal device. Other network elements only transparently transmit the PCO. Therefore, the PCO determines the data channel to be deleted between the terminal device and the session management network element, which is beneficial to improve the synchronization data channel. effectiveness.
  • the PCO includes information of the data channel to be deleted.
  • the present application also provides a communication method, including: a terminal device receives a deletion message and a PCO from a session management network element, the deletion message is used to indicate a data channel to be deleted;
  • the session management network element sends a response message of the PCO, the response message of the PCO is used to indicate that the terminal device has deleted the data channel to be deleted, or the response message of the PCO is used to indicate the terminal device It is determined to delete the data channel to be deleted, or the response message of the PCO is used to indicate that the terminal device has received the delete message.
  • PCO is the dedicated information between the session management network element and the terminal device. Other network elements only transparently transmit the PCO. Therefore, the PCO determines the data channel to be deleted between the terminal device and the session management network element, which is beneficial to improve the synchronization data channel. effectiveness.
  • the PCO includes information about the data channel to be deleted.
  • this application provides a communication device, which may be a session management network element or a chip in the session management network element.
  • the device may include a processing unit and a transceiving unit.
  • the processing unit may be a processor, and the transceiver unit may be a communication interface;
  • the session management network element may also include a storage unit, and the storage unit may be a memory; the storage unit is used for storing Instruction, the processing unit executes the instruction stored in the storage unit, so that the session management network element executes the method described in the seventeenth aspect.
  • the processing unit can be a processor, and the transceiver unit can be an input/output interface, a pin or a circuit, etc.; the processing unit executes the instructions stored in the storage unit to make
  • the session management network element executes the method described in the seventeenth aspect, and the storage unit may be a storage unit (for example, a register, a cache, etc.) in the chip, or a storage unit located outside the chip in the session management network element. Storage unit (for example, read only memory, random access memory, etc.).
  • this application provides another communication device, which may be a terminal device or a chip in the terminal device.
  • the device may include a processing unit and a transceiving unit.
  • the processing unit may be a processor, and the transceiving unit may be a transceiver;
  • the terminal device may also include a storage unit, and the storage unit may be a memory; the storage unit is used to store instructions, and the processing The unit executes the instructions stored in the storage unit, so that the terminal device executes the method described in the eighteenth aspect.
  • the processing unit may be a processor, and the transceiver unit may be an input/output interface, a pin or a circuit, etc.; the processing unit executes the instructions stored in the storage unit to make the terminal
  • the device executes the method described in the eighteenth aspect, and the storage unit may be a storage unit in the chip (for example, a register, cache, etc.), or a storage unit in the terminal device located outside the chip (for example, only Read memory, random access memory, etc.).
  • the present application provides a computer-readable storage medium in which a computer program is stored.
  • the processor executes the process described in the seventeenth aspect. method.
  • this application provides a computer-readable storage medium that stores a computer program in the computer-readable storage medium.
  • the processor executes the eighteenth aspect method.
  • the present application provides a computer program product, the computer program product comprising: computer program code, when the computer program code is executed by a processor, the processor executes the method described in the seventeenth aspect.
  • the present application provides a computer program product, the computer program product comprising: computer program code, when the computer program code is executed by a processor, the processor executes the method described in the eighteenth aspect.
  • FIG. 1 is a schematic diagram of a network architecture applicable to an embodiment of the present application
  • Figure 2 is a schematic diagram of a communication method provided by the present application.
  • FIG. 3 is a schematic diagram of another communication method provided by the present application.
  • FIG. 4 is a schematic diagram of another communication method provided by this application.
  • FIG. 5 is a schematic diagram of another communication method provided by this application.
  • FIG. 6 is a schematic diagram of still another communication method provided by this application.
  • FIG. 7 is a schematic diagram of yet another communication method provided by this application.
  • FIG. 8 is a schematic diagram of yet another communication method provided by this application.
  • FIG. 9 is a schematic diagram of a communication device provided by the present application.
  • FIG. 10 is a schematic diagram of a terminal device provided by this application.
  • FIG. 11 is a schematic diagram of yet another communication method provided by this application.
  • Fig. 12 is a schematic diagram of another communication method provided by the present application.
  • FIG. 1 is a network architecture suitable for an embodiment of the present application, and the network architecture includes a 4G communication system and a 5G communication system.
  • the 4G communication system (hereinafter referred to as "4G system” for short) may include the following network elements.
  • Radio access network, (R)AN) network element used to provide network access functions for authorized terminal equipment in a specific area, and can use different quality according to the level of terminal equipment and service requirements. Transmission tunnel.
  • (R)AN network elements can manage wireless resources, provide access services for terminal devices, and then complete the forwarding of control signals and terminal device data between terminal devices and the core network.
  • (R)AN network elements can also be understood as traditional networks Base station in.
  • (R)AN network elements can also be called evolved universal terrestrial radio access network (evovled universal terrestrial radio access network, E-UTRAN) or evolved base station (eNB), as shown in Figure 1. Show.
  • E-UTRAN evolved universal terrestrial radio access network
  • eNB evolved base station
  • network element may also be referred to as an entity, equipment, device, or module, etc., which is not particularly limited in this application.
  • the description of “network element” is omitted in part of the description.
  • the (R)AN network element is referred to as RAN for short.
  • the "(R)AN network “Element” should be understood as (R)AN network element network element or (R)AN entity, and the description of the same or similar situations is omitted below.
  • a mobility management entity (mobility management entity, MME) is used to provide mobility management functions.
  • MME can also provide functions such as lawful interception and access authorization/authentication.
  • a serving gateway (SGW) is used to provide functions such as user data forwarding.
  • Packet data network gateway user function (PGW-U) is used to provide the user plane function of the PDN gateway.
  • Packet data network gateway control function (PGW-C) is used to provide the control plane function of the PDN gateway.
  • PCRF policy and charging rules function
  • the home subscriber server including the user profile, is used to perform user authentication and authorization, and can provide information about the user's physical location.
  • the 5G communication system (hereinafter referred to as "5G system” for short) may include the following network elements.
  • (R)AN network element It is used to provide network access function for authorized terminal equipment in a specific area, and can use transmission tunnels of different quality according to the level of terminal equipment and service requirements.
  • the (R)AN network element may also be referred to as the next generation radio access network (NG-RAN, as shown in Figure 1) or the next generation base station (gNB).
  • NG-RAN next generation radio access network
  • gNB next generation base station
  • Access management function access and mobility management function, AMF
  • AMF access and mobility management function
  • AMF can also provide functions such as lawful monitoring and access authorization/authentication.
  • the AMF can communicate with the MME through the N26 interface.
  • the letters and numbers in the attachments between the various network elements represent the names of the communication interfaces between the various network elements.
  • the communication interfaces between the various network elements may also have other names. not limited.
  • UPF User plane function
  • QoS quality of service
  • the session management function is mainly used for session management, network interconnection protocol (IP) address allocation and management of terminal devices, selection and management of user plane functions.
  • SMF can also be the termination point of policy control and charging function interfaces.
  • PCF Policy control function
  • AMF Access Management Function
  • SMF Session Management Function
  • Unified data management (UDM) network elements are used to manage contracted data. In addition, it is also used for user service registration management, processing terminal equipment identification, access authentication, etc.
  • network elements with the same or similar functions can be set jointly.
  • UPF and PGW-U can be set together
  • SMF and PGW-C can be set together
  • PCF and PCRF can be set together
  • HSS and UDM can be set together
  • "+" in Figure 1 means that two devices can be set together.
  • the above-mentioned network architecture applied to this application is only an example of a network architecture described from the perspective of a service-oriented architecture.
  • the network architecture applicable to the embodiments of this application is not limited to this, and any network element that can realize the functions of the above-mentioned network elements All network architectures are applicable to the embodiments of this application.
  • the foregoing network elements or functions may be network elements in hardware devices, software functions running on dedicated hardware, or virtualization functions instantiated on a platform (for example, a cloud platform).
  • the terminal equipment can be switched from the 4G communication system to the 5G communication system, or it can be switched from the 5G communication system to the 4G communication system.
  • Terminal devices can include various handheld devices with wireless communication functions, vehicle-mounted devices, wearable devices, computing devices or other processing devices connected to wireless modems, as well as various forms of terminals, mobile stations (MS), terminals (terminal), user equipment (UE), soft terminal, etc. For example, water meters, electricity meters, sensors, etc.
  • the terminal device or any of the aforementioned network devices includes a hardware layer, an operating system layer running on the hardware layer, and an application layer running on the operating system layer.
  • the hardware layer includes, for example, hardware such as a central processing unit (CPU), a memory management unit (MMU), and memory (also referred to as main memory).
  • the operating system may be any one or more computer operating systems that implement business processing through processes, for example, Linux operating system, Unix operating system, Android operating system, iOS operating system, or windows operating system.
  • the application layer includes applications such as browsers, address books, word processing software, and instant messaging software.
  • the embodiments of the application do not specifically limit the specific structure of the execution body of the method provided in the embodiments of the application, as long as the program that records the code of the method provided in the application can be used to communicate according to the method provided in the application.
  • the execution subject of the method provided in the embodiments of the present application may be a terminal device or a network device, or a functional module in the terminal device or the network device that can call and execute the program.
  • the communication method provided in this application involves multiple network elements, and different network elements correspond to different processing steps, but these steps are all different implementations based on one inventive idea. In order to clearly introduce the improvements of each network element, first The communication method provided by this application will be described from the perspective of different network elements.
  • FIG. 2 is a communication method provided by this application from the perspective of a session management network element, and the method 200 includes:
  • the session management network element determines a first data channel in the first system, where the first data channel is a data channel to be synchronized with the terminal device.
  • the aforementioned session management network element may be SMF+PGW-C in FIG. 1.
  • the first system is a 4G system or a 5G system.
  • the first data channel is the first evolved packet system (EPS) bearer;
  • EPS evolved packet system
  • the first data channel is the first QoS flow.
  • first and second only refer to different individuals in the same type of things, and there are no other restrictions.
  • the first data channel represents one or more data channels
  • the first system and the second system represent two different communication systems.
  • the session management network element and the terminal device may store different data channel information due to some reasons.
  • the terminal device when the session management network element deletes the first data channel in the first system and instructs the terminal device to delete the data channel, the terminal device is in an idle state (idle) or a communication failure occurs, the terminal The device cannot receive the message sent by the session management network element in the first system. Therefore, the terminal device does not delete the first data channel, which results in inconsistencies between the session management network element and the data channel information saved by the terminal device, which may cause communication problems between the session management network element and the terminal device after the communication system is switched.
  • the terminal device deletes the first data channel in the first system but fails to notify the session management network element, it may also cause communication problems between the session management network element and the terminal device after the communication system is switched. .
  • data channel can be equivalent to “data channel information”.
  • deleting a data channel can be interpreted as deleting data channel information, which is the parameter or configuration information corresponding to the data channel.
  • the session management network element In order to ensure normal communication after the communication system is switched, the session management network element first needs to determine the first data channel, that is, the data channel to be synchronized with the terminal device, which can also be called the data channel that needs to be synchronized with the terminal device.
  • the data channel to be synchronized with the terminal device refers to the data channel that the network side has not successfully notified the terminal device to delete.
  • the data channel to be synchronized with the terminal device refers to the data channel that the terminal device has deleted but has not notified the network side.
  • the data channel to be synchronized with the terminal device is the EPS bearer that the terminal device has deleted but has not notified the network side.
  • the session management network element may determine the first data channel through multiple methods. In the following, several examples in which the session management network element determines the first data channel are given.
  • the session management network element may obtain the first state information from the terminal device. For example, the terminal device sends the first status information to the MME or AMF, and the MME or AMF sends the first status information to the session management network element after receiving it.
  • the first status information is used to indicate the status of the data channel in the terminal device. For example, an attach request (attach request) message, a registration request (registration request) message, or a session establishment request message sent by the terminal device may carry the first state information.
  • the session management network element may determine the first data channel according to the first state information. For example, the session management network element also saves the state information of the data channel. After the session management network element obtains the first state information from the MME or AMF, it can compare the two state information. The data channel with inconsistent state information is the first Data channel.
  • the session management network element sends protocol configuration options (protocol configuration options, PCO) to the terminal device.
  • the PCO may include information about the first data channel and/or information about the second data channel, or may not include any information.
  • the second data channel is a data channel corresponding to the first data channel in the second system. For example, when the first data channel is a bearer, the second data channel is a QoS flow mapped by the bearer; when the first data channel is a QoS flow, the second data channel is a bearer mapped by the QoS flow.
  • the aforementioned PCO is used to instruct the terminal device to delete the first data channel and/or the second data channel.
  • the PCO is a parameter for transferring information between the terminal device and the session management network element, and its function is similar to a container, which can carry different information.
  • network elements other than the terminal device and the session management network element will not parse the content in the PCO.
  • the session management network element may determine the first data channel based on receiving the response message that does not include the PCO, that is, determine that the data channel corresponding to the PCO sent by the session management network element is the first data channel.
  • the PCO sent by the session management network element may be associated with the PCO sent by the terminal device, and the association method may be: matching the identification parameter in the PCO cell header.
  • the PCO cell header sent by the session management network element carries the field a
  • the PCO cell header in the PCO corresponding message sent by the terminal device carries the field b.
  • the field a is the same as the field b, or the field a and the field b have an association relationship. This application does not limit the association method of the above two PCOs.
  • the PCO sent by the session management network element may be carried in different messages, and this application does not limit the message carrying the PCO.
  • the message bearing the PCO may be a bearer deletion request; when the terminal device switches from the 5G system to the 4G system, the message bearing the PCO may be an AMF service message or a NAS message.
  • the session management network element sends a first message to the MME or AMF, where the first message carries information about one or more data channels and is used to instruct the terminal device to delete the one or more data channels. If the session management network element receives a second message from the MME or AMF, and the second message is used to indicate that the first message is not notified to the terminal device, the session management network element determines that the one or more data channels are the first data channels.
  • the above-mentioned first message may be a bearer deletion request.
  • the above-mentioned second message may be a delete bearer response, and the delete bearer response includes indication information indicating that the first message has not been notified to the terminal device, and this application does not limit the specific form of the indication information.
  • the above-mentioned first message may be an AMF service message or a NAS message.
  • the above-mentioned second message may be a delete bearer response, and the delete bearer response includes indication information indicating that the first message has not been notified to the terminal device, and this application does not limit the specific form of the indication information.
  • the above example is an example in which the session management network element actively determines the first data channel. After the session management network element actively determines the first data channel, it can send the first indication information to other core network elements (for example, MME and AMF). An indication information is used to indicate the first data channel, so that other core network elements can synchronize the local data channel.
  • MME Mobility Management Entity
  • AMF Access Management Function
  • the session management network element may also determine the first data channel according to instruction information sent by other network elements. As shown in the following example.
  • the session management network element receives second indication information from the mobility management network element, and the second indication information indicates the first data channel. In this way, the session management network element does not need to actively determine the first data channel, which reduces the burden of the session management network element.
  • the method for the mobility management network element to determine the first data channel will be described in detail below.
  • the session management network element determines the first data channel, the following steps can be performed.
  • the session management network element synchronizes at least one of the following in the process of the terminal device switching from the first system to the second system: the first data channel, or the second data corresponding to the first data channel in the second system aisle.
  • the purpose of synchronizing the first data channel and the second data channel is to make the data channel information stored by the session management network element and the terminal device the same.
  • the session management network element if the session management network element deletes the first data channel without notifying the terminal device, the session management network element instructs the terminal device to delete the first data channel in S220.
  • the session management network element may delete the first data channel immediately after marking the first data channel, and then instruct the terminal device to delete the first data channel after it can communicate with the terminal device normally; the session management network element may also mark the first data channel The first data channel is retained after the channel, and the first data channel is deleted after the terminal device is instructed to delete the first data channel.
  • the session management network element deletes the locally stored first data channel in S220.
  • the information of the first data channel includes information carried by the evolved packet system (EPS)
  • the information of the second data channel includes information related to the
  • the EPS bears the information of the associated QoS flow.
  • the information carried by the EPS may be the identity of the EPS bearer or the QoS parameters of the EPS bearer.
  • the information of the QoS flow can be QoS rules or QoS parameters. Or, when the first system is a 5G system and the second system is a 4G system, the information of the first data channel includes information of the QoS flow, and the information of the second data channel includes information of the EPS bearer associated with the QoS flow.
  • the session management network element may trigger the session modification process when the terminal device is switched from the first system to the second system, and the session modification process is used for Synchronize the first data channel and/or the second data channel.
  • the above session modification process can be a protocol data unit (PDU) session modification process, a PDU session release process or a PDU session deactivation process; to synchronize the bearer of the 4G communication system
  • PDU protocol data unit
  • the above-mentioned session modification process may also be a bearer modification process or a bearer deactivation process.
  • the session management network element can release the first data channel and delete the locally stored information of the second data channel .
  • SMF can release the EPS bearer that the terminal device failed to notify the network side to delete before, and delete the locally stored QoS rules and QoS of the QoS flow corresponding to the EPS bearer parameter.
  • the data channel information saved by each communication device after the communication system is switched is consistent, which avoids the possibility of communication failure after the communication system is switched.
  • this application also discloses a communication method executed by a terminal device.
  • the method includes: the terminal device determines that the terminal device has been deleted in the first system but does not notify the first data channel of the network side; the terminal device sends first status information to the session management network element, the first status information indicating the The state of the data channel in the terminal device, and the first state information is used to determine the first data channel.
  • the terminal device sends the first status information to the MME or AMF, and the MME or AMF sends the first status information to the session management network element after receiving it.
  • the attachment request message, the registration request message, or the session establishment request message sent by the terminal device may carry the first state information.
  • the session management network element may determine the first data channel according to the first state information.
  • the mobility management network element Similar to the session management network element, the mobility management network element also stores data channel information. Therefore, when the data channel information stored by the terminal device is different from the data channel information stored by the mobility management network element, the mobility management network element also needs to perform synchronization processing. For example, the mobility management network element may perform the following steps according to the method 300 shown in FIG. 3.
  • the mobility management network element in the second system determines a first data channel in the first system, where the first data channel is a data channel to be synchronized with the terminal device.
  • the meanings of the first system, the second system, and the first data channel are the same as the meanings of the corresponding terms in the method 200, and will not be repeated here.
  • the mobility management network element in the second system is an MME;
  • the mobility management network element in the second system is an AMF.
  • the mobility management network element may actively determine the first data channel.
  • the mobility management network element may further instruct the session management network element after determining the first data channel.
  • the mobility management network element may also wait for the instruction of the session management network element, and determine the first data channel according to the instruction of the session management network element.
  • Case 1 The mobility management network element actively determines the first data channel.
  • the mobility management network element in the second system receives the first status information from the terminal device, and the first status information is used to indicate the status of the data channel of the terminal device; the mobility management network element in the second system receives the first status information from the terminal device.
  • the mobility management network element receives second status information, and the second status information is used to indicate the status of the data channel of the terminal device; the mobility management network element in the second system determines the first status information and the second status information.
  • the above two status information is data channel information stored by different network elements.
  • the mobility management network element in the second system can compare the status of the data channel indicated by the two status information and determine that the data channel with different status is the first One data channel.
  • the mobility management network element in the second system is AMF
  • the AMF can obtain the second status information from the MME through the N26 interface
  • the AMF can obtain the first state information through the N1 interface. Status information so that the first data channel can be determined.
  • the AMF may send the second indication information to the session management network element to indicate the second data channel, thereby reducing the burden of the session management network element.
  • the mobility management network element in the second system is the MME
  • the MME can obtain the second state information from the AMF through the N26 interface
  • the AMF can be from the E-UTRAN
  • the terminal device obtains the first status information, so that the first data channel can be determined.
  • the MME may send second indication information to the session management network element to indicate the second data channel, thereby reducing the burden of the session management network element.
  • Case 2 The mobility management network element determines the first data channel according to the instruction of the session management network element.
  • the mobility management network element in the second system may receive the first indication information from the session management network element, where the first indication information is used to indicate the first data channel, so that the mobility management network element can determine the first data channel.
  • the method for the session management network element to determine the first data channel is as described in method 200, which will not be repeated here.
  • the mobility management network element may send the first state information to the session management network element to facilitate session management The network element determines the first data channel.
  • the mobility management network element in the second system can perform the following steps after determining the first data channel.
  • the mobility management network element in the second system synchronizes at least one of the following in the process of the terminal device switching from the first system to the second system: the first data channel, or, the second system and the first system The second data channel corresponding to the data channel.
  • the session management network element can trigger the PDU session modification process or the PDU session release process, and the AMF can synchronize the first data channel and/or the second data channel in the PDU session modification process or the PDU session release process; the session management network element can trigger In the bearer modification process or the bearer deactivation process, the MME may synchronize the first data channel and/or the second data channel in the bearer modification process or the bearer deactivation process.
  • the mobility management network element may also synchronize the first data channel and/or the second data channel in the PDU session activation process triggered by the session management network element.
  • the mobility management network element in the second system may also actively initiate a synchronization process.
  • the mobility management network element in the second system transfers to the second system after the terminal device is switched from the first system to the second system.
  • the session management network element of the second system initiates a session modification process, and the session modification process is used to synchronize at least one of the following: a first data channel, or a second data channel corresponding to the first data channel in the second system.
  • the foregoing session modification process may be a PDU session modification process, a PDU session release process, or a bearer modification process or a bearer deactivation process.
  • the mobility management network element in the second system may also synchronize the first data channel and/or the second data channel through the session deletion process.
  • the terminal device Similar to the core network element, the terminal device also stores data channel information. Therefore, when the data channel information stored by the terminal device is different from the data channel information stored by the core network element, the terminal device also needs to perform synchronization processing. For example, the terminal device may execute the following steps according to the method 400 shown in FIG. 4.
  • the terminal device determines a first data channel in the first system, where the first data channel is a data channel to be synchronized with the session management network element.
  • the meanings of the first system, the second system and the first data channel are the same as the meanings of the corresponding terms in the method 200, and will not be repeated here.
  • the terminal device can determine the first data channel in the following ways.
  • the existence of a data channel to be synchronized on the terminal device may be because the terminal device has not received the message sent by the core network element to delete the first data channel. For example, the terminal device is in an idle state or a communication failure occurs. At this time, the terminal device may determine the first data channel according to the instruction of the core network element. For details, refer to the embodiments in the method 200 and the method 300. That is to say, in mode 1, the data channel to be synchronized with the session management network element may also be referred to as the data channel that needs to be synchronized with the session management network element. For example, the data channel to be synchronized with the session management network element refers to the data channel for which the session management network element has been deleted but the terminal device has not been notified.
  • the terminal device may send first status information to the core network element during the communication system switching process, and the first status information indicates the data channel in the terminal device , So that the core network element determines the data channel that needs to be synchronized (that is, the first data channel) according to the first state information.
  • the terminal device may also determine the first data channel according to the received second state information, and the second state information is used to indicate the state of the data channel in the session management network element. This will be further described in conjunction with Figure 12.
  • the terminal device may actively request to obtain the second state information after the communication system is switched or during the communication system switching process.
  • the presence of a data channel to be synchronized on the terminal device may also be because the terminal device actively deleted the first data channel but failed to notify the core network element.
  • the terminal device sends a notification message to the session management network element, and the notification message is used to notify the session management network element that the terminal device has deleted one or more data channels; if the terminal device does not receive a response message to the notification message, the terminal device
  • the one or more data channels may be determined as the first data channel.
  • the terminal device can also obtain the first data channel in the following manner.
  • the terminal device sends a PCO to the session management network element. If the terminal device does not receive a response message from the PCO, or the response message received by the terminal device does not contain the PCO, it indicates that there is a problem with the communication between the terminal device and the session management network element , The terminal device may determine that one or more data channels deleted before are the first data channels.
  • the PCO sent by the terminal device includes at least one of the information of the first data channel and the information of the second data channel.
  • the terminal device can perform the following steps after determining the first data channel.
  • the terminal device synchronizes at least one of the following in the process of switching from the first system to the second system: the first data channel, or, the second data channel corresponding to the first data channel in the second system.
  • the terminal device may notify the core network element (for example, the session management network element) to delete the first data channel or the second data channel in S420 At least one of.
  • the terminal device can delete the first data channel immediately after marking the first data channel, and notify the core network element to delete the first data channel after it can communicate with the core network element; the terminal device can also mark the first data channel The first data channel is retained after the channel, and the first data channel is deleted after the core network element is notified to delete the first data channel.
  • the terminal device deletes the locally stored information of the first data channel or the information of the second data channel in S420 At least one of.
  • the information of the first data channel or the information of the second data channel reference may be made to the description in FIG. 2, which will not be repeated here.
  • the terminal device can release the first data channel in the session modification process triggered by the core network element during the process of switching from the first system to the second system.
  • the session modification process is used to synchronize the second system.
  • the aforementioned session modification process may be a PDU session modification process, a PDU session release process, or a bearer modification process or a bearer deactivation process.
  • the session management network element can trigger a session modification process or a session release process, in which the terminal device synchronizes the first data channel and/or the second data channel; when the terminal device After switching from the 5G system to the 4G system, the session management network element can trigger a bearer modification process or a bearer deactivation process, in which the terminal device synchronizes the first data channel and/or the second data channel.
  • the terminal device may also trigger the PDU session deactivation process after the terminal device initiated by the session management network element switches from the first system to the second system, and synchronize the first data channel and/or the second data channel.
  • the terminal device may also initiate a session modification process to synchronize the first data channel and/or the second data channel.
  • the terminal device deletes at least one of the information of the first data channel or the information of the second data channel.
  • the information of the first data channel includes information of the evolved EPS bearer
  • the information of the second data channel includes information of the QoS flow associated with the EPS bearer
  • the information of the first data channel includes the information of the QoS flow
  • the information of the second data channel includes the information of the EPS bearer associated with the QoS flow.
  • the above-mentioned QoS flow information may be QoS rules or QoS parameters of the QoS flow.
  • the terminal device may release the first data channel and delete the locally stored information of the second data channel.
  • the terminal device can release the EPS bearer that the network side failed to notify the terminal device to delete before, and delete the locally stored QoS rules and QoS rules of the QoS flow corresponding to the EPS bearer.
  • QoS parameters may be included in the above two implementation manners.
  • Figure 5 shows a communication method provided by this application.
  • the method is described by taking a scenario where a terminal device switches from a 4G system to a 5G system as an example.
  • it is also applicable to a scenario where a terminal device switches from a 5G system to a 4G system.
  • this method can be applied to the case of N26 interface and no N26 interface.
  • the method in FIG. 5 may be applicable to a case where the SMF+PGW-C deletes the first bearer and/or the first QoS flow without notifying the UE.
  • the method includes the following steps:
  • SMF+PGW-C sends a delete bearer request to the MME to request deletion of the first bearer, where the first bearer may be one or more bearers.
  • the message may include a PCO, and the PCO may instruct the UE to delete the first bearer and/or the QoS flow mapped by the first bearer (ie, the first QoS flow).
  • deleting the first bearer can be understood as deleting the parameter corresponding to the first bearer.
  • Deleting the first QoS flow can be understood as deleting the QoS flow identifier (QFI) and QoS rules corresponding to the first QoS flow.
  • QFI QoS flow identifier
  • the MME cannot send a bearer deletion request to the UE.
  • the MME sends a delete bearer response to SMF+PGW-C.
  • the MME may delete the local first bearer information according to the bearer delete request, or it may mark the first bearer and delete it after subsequent steps.
  • the UE in the idle state switches from 4G to 5G, it sends a registration request to the NG-RAN. In other words, the UE initiates the 4G to 5G mobility registration process.
  • the NG-RAN sends the registration request of the UE to the AMF.
  • the specific process can refer to the communication protocol (3GPP TS 23.502: "Procedures for the 5G System; Stage 2").
  • AMF sends a session establishment request to SMF+PGW-C.
  • SMF+PGW-C can determine the bearers to be deleted that have not been notified to the UE according to different methods.
  • the SMF+PGW-C can instruct the UE to delete the above-mentioned bearer to be deleted and the QoS flow mapped by the bearer in various ways.
  • SMF+PGW-C may determine the bearer to be deleted (that is, the first bearer) not notified to the UE according to any of the following methods.
  • the registration request sent in the above steps 505 and 506 carries indication information 1.
  • the indication information 1 may indicate the EPS bearer status (EPS bearer status) and/or the QoS flow status (QoS flow status) on the UE.
  • the indication information 1 is the first status information described above.
  • the session establishment request in step 510 carries the indication information 1 sent by the UE.
  • the indication information 1 is included in the session establishment request message, or included in the PCO in the session establishment request message, or may also be included in other messages and sent to the UE.
  • SMF+PGW-C After SMF+PGW-C receives the session establishment request, it can determine the first bearer according to the indication information 1. For example, SMF+PGW-C may determine that the bearer indicated by indication information 1 is different from the local bearer of SMF+PGW-C as the first bearer.
  • Method b (applicable to the N26 interface between the AMF and the MME): After the MME receives the bearer deletion request in step 501 and finds that it cannot connect to the UE, the MME can mark the first bearer in step 502. For example, the possible reasons for not being able to connect to the UE are: loss of wireless signal or the UE entering an idle state.
  • the MME may store the identity of the first bearer.
  • the MME may also mark the first bearer by other methods. For example, the MME binds or maps the identifier of the first bearer with a specific field; or, the MME modifies some fields in the context of the first bearer; or, the MME records or stores the bearer ID that is not sent to the UE. This application does not limit the method for the MME to mark the first bearer.
  • the AMF After the AMF receives the registration request in step 506, in step 507, it requests to obtain the UE context from the MME through the N26 interface. After that, in step 508, the MME sends the context of the UE to the AMF.
  • the context may include indication information 2, which is used to indicate the first bearer marked by the MME.
  • the indication information 2 may be carried in the EPS bearer status of the context.
  • the MME may also separately send the above-mentioned indication information 2 to the AMF, and the present invention does not limit the specific form and sending manner of the indication information 2.
  • the AMF After the AMF obtains the indication information 2 from the MME, it will send the indication information 2 to the SMF+PGW-C through the session establishment request in step 510.
  • SMF+PGW-C may determine the first bearer according to the indication information 2. Since the bearer indicated by the indication information 2 is a bearer marked by the MME, the bearer indicated by the indication information 2 is the first bearer.
  • steps 502, 507, and 508 in FIG. 5 are optional steps.
  • Method c (applicable to the N26 interface between AMF and MME): Combine the above method a and method c, that is, the session establishment request in step 510 carries both indication information 1 and indication information 2, then, SMF+PGW-C The first bearer can be determined by combining the indication information 1 and the indication information 2, so as not to omit the bearers that need to be synchronized.
  • Method d After SMF+PGW-C receives the bearer deletion response in step 503, it can be determined in step 504 that the first bearer needs to be synchronized.
  • the MME may choose to execute one of the following three processing methods, so that SMF+PGW-C can determine in step 504 that the first bearer needs to be synchronized.
  • the MME may add the identity of the first bearer to the bearer deletion response, and after receiving the bearer deletion response, the SMF+PGW-C can determine that the first bearer needs to be synchronized.
  • the MME can also send a delete bearer response directly. Since the MME is not connected to the UE, the delete bearer response does not include the PCO sent by the UE. After SMF+PGW-C receives the response message that does not include the PCO, the delete bearer request can be determined The first bearer in needs to be synchronized.
  • the MME may also send separate indication information or cause value (cause) to SMF+PGW-C.
  • the cause value may use the RAN cause value or non-access stratum (NAS) cause value in the prior art, or Use the new reason value.
  • NAS non-access stratum
  • SMF+PGW-C can also combine method d with any one of the foregoing methods a, b, and c to determine that the first bearer needs to be synchronized.
  • SMF+PGW-C may mark the first bearer.
  • SMF+PGW-C may store the identity of the first bearer.
  • the method for marking the first bearer by SMF+PGW-C can refer to the method for marking the first bearer by the MME.
  • the SMF+PGW-C can delete the first bearer and/or the first QoS flow after marking the first bearer, or it can delete the first bearer and the first QoS flow until synchronization. If the SMF+PGW-C does not delete the first bearer and/or the first QoS flow in step 504, the first bearer and/or the first QoS flow may be deleted in the subsequent step 511 or step 517.
  • the method includes:
  • SMF+PGW-C indicates the UE synchronization bearer status.
  • SMF+PGW-C can indicate the UE synchronization bearer status according to one of the following three methods.
  • SMF+PGW-C initiates a session modification process, that is, step 517.
  • Step 517 can be performed at any time after step 511.
  • the session modification process may be a PDU session modification process or a PDU session release process.
  • SMF+PGW-C sends a session establishment response message to AMF.
  • the AMF sends a registration acceptance (registration accept) message to the NG-RAN. 514.
  • the NG-RAN sends a registration acceptance message to the UE.
  • the SMF+PGW-C carries indication information 3 in the session establishment response message in step 512, and correspondingly, the registration acceptance messages in steps 513 and 514 carry the indication information 3.
  • the indication information 3 is used to indicate the UE synchronization bearer status.
  • the indication information 3 instructs the UE to delete the first bearer and/or the first QoS flow.
  • the indication information 3 may be included in the session establishment response message, or included in the PCO in the session establishment response message, or may also be included in other messages and sent to the UE.
  • the UE may delete the local first bearer and/or the first QoS flow according to the indication information 3, or the UE may also initiate a session modification procedure according to the indication information 3 to delete the local first A bearer and/or the first QoS flow.
  • SMF+PGW-C can send the PCO in step 501 in steps 512-514; or, after completing the 4G to 5G interworking process (after step 514 and before step 516, not shown in the figure), SMF+PGW-C sends another PCO to the UE.
  • the PCO can be sent separately or included in other 5G process messages and sent to the UE.
  • the PCO message instructs the UE to delete the first bearer and/or the first QoS flow.
  • the SMF+PGW-C can initiate the session modification process, and the UE deletes it during the session modification process The first bearer and/or the first QoS flow.
  • step 515 may be performed before or after the response message is sent in step 516.
  • the SMF+PGW-C confirms that the UE has deleted or the first bearer and/or first QoS flow to be deleted after receiving the PCO response. If the SMF+PGW-C does not delete the locally stored first bearer and/or the first QoS flow in step 511 and step 504, the first bearer and/or the first QoS flow may be deleted in step 517.
  • the UE may delete the first bearer and/or the first QoS flow in the session modification process initiated by SMF+PGW-C (step 517), if SMF+PGW-C does not delete the locally stored data in step 511 and step 504
  • the first bearer and/or the first QoS flow may be deleted in step 517.
  • SMF+PGW-C sends a session establishment response message to AMF.
  • SMF+PGW-C executes the method (2) in step 511, and the session establishment response message includes indication information 3.
  • the indication information 3 may be a separate indication information or information contained in the PCO. If the instruction message 3 is sent, steps 516-517 are not executed.
  • SMF+PGW-C executes method (3) in step 511, and sends a session establishment response message containing the PCO in step 501, and the PCO instructs the UE to delete the first bearer and/or the first QoS flow.
  • AMF sends a registration acceptance message (registration accept) to NG-RAN.
  • the registration acceptance message includes indication information 3.
  • the indication information 3 may be separate indication information or information carried in the PCO.
  • the registration acceptance message includes the PCO in step 501, and the PCO instructs the UE to delete the first bearer and/or the first QoS flow.
  • the NG-RAN sends a registration acceptance message to the UE.
  • the registration acceptance message includes indication information 3.
  • the indication information 3 may be separate indication information or information carried in the PCO.
  • the registration acceptance message includes the PCO in step 501, and the PCO instructs the UE to delete the first bearer and/or the first QoS flow.
  • This step is optional.
  • step 515 is not executed.
  • the UE deletes the first bearer and/or the first QoS flow according to the indication information 3.
  • the UE initiates a session modification procedure according to the instruction information 3, and steps 516-517 are omitted at this time.
  • step 515 can be performed before or after step 516, and step 517 can be omitted (SMF+PGW-C deletes the locally stored first bearer and/or first QoS flow in step 511 or step 504), or SMF+PGW-C deletes the local first bearer and/or in step 517
  • the first QoS flow did not delete the locally stored first bearer and/or the first QoS flow in step 511 and step 504).
  • step 515 is not executed .
  • the UE sends a PCO response message to SMF+PGW-C.
  • the PCO response message is used to notify SMF+PGW-C that the UE has confirmed the first bearer and/or first QoS flow to be deleted, or, the PCO response message Used to notify SMF+PGW-C that the UE has deleted the local first bearer and/or first QoS flow.
  • This step is optional.
  • SMF+PGW-C executes method (3) in step 511
  • SMF+PGW-C will initiate a session modification process after receiving the PCO response message in step 516.
  • the session modification process is used to trigger the UE to delete the first bearer and / Or the first QoS flow.
  • SMF+PGW-C does not delete the first bearer and/or the first QoS flow in step 504 or step 511, the first bearer and/or the first QoS flow may be deleted in step 517.
  • the specific process can refer to the existing agreement.
  • SMF+PGW-C is In step 517, the local first bearer and/or the first QoS flow are deleted.
  • step 517 can be executed at any time after step 511.
  • the method shown in FIG. 5 is a method for SMF+PGW-C to determine the data channel to be synchronized.
  • SMF+PGW-C can also determine the data channel to be synchronized according to the following method. If SMF+PGW-C initiates the bearer deletion process in the 4G system, SMF+PGW-C marks the bearer deletion process initiated by it. When the UE completes the registration process of the 5G system, SMF+PGW-C will trigger the session modification process. To synchronize the data channel of the UE and SMF+PGW-C.
  • SMF+PGW-C records whether it initiates the bearer deletion process. If multiple bearer deletion processes occur in the 4G network (each bearer deletion process can delete one or more bearers) , Then SMF+PGW-C can be marked once or multiple times. If SMF+PGW-C is marked only once, only the first bearer deletion process or the last bearer deletion process can be marked. Subsequently, SMF+PGW-C can trigger a session modification process to synchronize the data channel of the UE and SMF+PGW-C.
  • the UE if the UE deletes a bearer, the UE records the deleted bearer. After the communication system is switched, the UE initiates a session modification process to synchronize the data channel with the core network element.
  • the foregoing embodiment mainly describes the method of SMF+PGW-C instructing the UE to synchronize.
  • the AMF may also instruct the UE to synchronize. As shown in Figure 6.
  • This method is also described by taking a scenario where a terminal device switches from a 4G system to a 5G system as an example. In addition, it is also applicable to a scenario where a terminal device switches from a 5G system to a 4G system. And, this method can be applied to the situation with N26 interface.
  • the method in FIG. 6 is also applicable to the case where the SMF+PGW-C deletes the first bearer and/or the first QoS flow without notifying the UE.
  • steps 601-603 and 605-609 reference may be made to the description of steps 501-503 and 505-509 in FIG. 5, which will not be repeated.
  • the AMF may determine the bearer to be deleted (that is, the first bearer) that has not been notified to the UE according to any of the following methods.
  • the registration request sent in steps 605 and 606 carries the above instruction information 1.
  • the AMF may determine the first bearer according to the indication information 1. For example, the AMF may determine that the bearer indicated by the indication information 1 that is different from the local bearer of the AMF is the first bearer.
  • Method f After the MME receives the bearer deletion response in step 601 and finds that it cannot connect to the UE, the MME can mark the first bearer in step 602.
  • the AMF receives the registration request in step 606, in step 607, it requests the UE context from the MME through the N26 interface.
  • the MME sends the context of the UE to the AMF.
  • the context may include the above-mentioned indication information 2.
  • the AMF may determine the first bearer according to the indication information 2. Since the bearer indicated by the indication information 2 is a bearer marked by the MME, the bearer indicated by the indication information 2 is the first bearer.
  • Method g Combining the above method e and method f, that is, the AMF can determine the first bearer by combining the indication information 1 and the indication information 2, so as not to miss the bearer steps that need to be synchronized. For example, the AMF may first determine that the bearer indicated by the indication information 1 is different from the local bearer of the AMF as the candidate bearer for the first bearer, and then determine the first bearer in combination with the indication information 2, so as not to omit the bearer that needs synchronization.
  • the AMF sends a registration acceptance message to the UE.
  • the registration acceptance message carries indication information 4 for instructing the UE to synchronize the first bearer.
  • the indication information 4 may instruct the UE to delete the first bearer and/or the first QoS flow.
  • the NG-RAN forwards the instruction information 4 sent by the AMF to the UE.
  • the indication information 4 may directly instruct the UE to delete the first bearer and/or the first QoS flow, or the indication information 4 may also instruct the UE to initiate a session modification procedure.
  • the UE After the UE receives the corresponding indication information, it deletes the first bearer and/or the first QoS flow, or initiates a session modification procedure to facilitate the synchronization of the AMF and SMF+PGW-C bearers.
  • the above embodiments mainly describe the communication method when the UE is handed over from the 4G system to the 5G system.
  • the communication method when the UE is handed over from the 5G system to the 4G system will be described with reference to FIGS. 7 and 8.
  • the method shown in FIG. 7 is applicable to scenarios where the UE switches from a 5G system to a 4G system, and is applicable to scenarios with and without N26 interfaces.
  • SMF+PGW-C can mark the data channel to be deleted but not notified to the UE (ie, the first QoS flow) according to different methods.
  • the SMF+PGW-C can instruct the terminal to delete the first QoS flow and the bearer mapped by the first QoS flow in various ways.
  • the method includes the following steps:
  • SMF+PGW-C sends AMF servicing message to AMF through the 5G system, instructing AMF to delete the first QoS flow.
  • the first QoS flow may be one or more QoS flows.
  • the AMF servicing message may include a PCO, and the PCO may instruct the UE to delete the first QoS flow and/or the bearer mapped by the first bearer (ie, the first bearer). For example, deleting the parameters corresponding to the first QoS flow, and deleting the EPS bearer identifier (EBI) and other parameters corresponding to the first QoS flow.
  • EBI EPS bearer identifier
  • the session modification message cannot be sent to the UE.
  • AMF can delete local bearer information according to the AMF servicing message. Or, because it is found that it cannot be connected to the UE (possible reasons: wireless signal loss, UE entering idle state, etc.), the AMF can mark the first QoS flow in this step. For example, the AMF can store the identification of the first QoS flow. Delete it after the next steps.
  • the AMF may also mark the first QoS flow by other methods. For example, the AMF binds or maps the identifier of the first QoS flow with a specific field; or the AMF modifies some fields in the context of the first QoS flow. This application does not limit the method for AMF to mark the first QoS flow.
  • AMF initiates a session modification request to SMF+PGW-C and obtains a response message.
  • the AMF may notify SMF+PGW-C that the first QoS flow has not been deleted by the UE, and the notification method is as follows.
  • the AMF can add the identifier of the first QoS flow to the session modification request. After receiving the session modification request, the SMF+PGW-C can determine that the first QoS flow needs to be synchronized.
  • AMF can also send a session modification request directly. Since AMF is not connected to the UE, the session modification request does not include the PCO sent by the UE. After SMF+PGW-C receives the response message that does not include the PCO, the servicing request can be determined The first QoS flow in needs to be synchronized.
  • AMF can also send separate indication information or cause value (cause) to SMF+PGW-C.
  • the cause value can use the RAN cause value or the non-access stratum (NAS) cause value in the prior art, or Use the new reason value.
  • NAS non-access stratum
  • the SMF+PGW-C may mark the first QoS flow.
  • the SMF+PGW-C may store the identification of the first QoS flow.
  • Step 704 is an optional step.
  • the method of SMF+PGW-C marking the first QoS flow can refer to the method of AMF marking the first QoS flow.
  • the SMF+PGW-C may delete the first bearer and/or the first QoS flow after marking the first QoS flow, or may reserve the first bearer and the first QoS flow until synchronization and then delete.
  • the SMF+PGW-C does not delete the first bearer and/or the first QoS flow in step 704, the first bearer and/or the first QoS flow may be deleted in step 709 or 713 or 718.
  • steps 701 to 704 are only applicable to the case where the SMF+PGW-C deletes the first bearer and/or the first QoS flow without notifying the UE.
  • a UE in an idle state switches from a 5G system to a 4G system, if there is no N26 interface, the UE sends an attach request to E-UTRAN, and steps 707-711 are omitted; if there is an N26 interface, the UE sends to E-UTRAN Tracking area update (TAU) request. At this time, steps 707-711 cannot be omitted.
  • TAU E-UTRAN Tracking area update
  • the attach request or the TAU request may include indication information 5.
  • the indication information 5 may indicate the EPS bearer status (EPS bearer status) and/or the QoS flow status (QoS flow status) on the UE.
  • the indication information 5 is the first state information mentioned above.
  • the above-mentioned indication information 5 may indicate the first QoS flow instead of all QoS flows local to the UE.
  • the UE may also use indication information 5 to indicate the EPS bearer status and/or QoS flow status on the UE at this time.
  • the UE may also send the foregoing indication information 5 to SMF+PGW-C through the PCO.
  • the E-UTRAN sends the UE's attach request or TAU request to the AMF.
  • the attach request or TAU request includes indication information 5 sent by the UE.
  • the MME requests the UE's context information from the AMF through the N26 interface.
  • the context acquisition request may carry indication information 5.
  • the AMF requests the SMF+PGW-C to obtain the context information of the UE.
  • the context acquisition request may carry indication information 5.
  • SMF+PGW-C synchronizes QoS flow status. This step is optional.
  • SMF+PGW-C may determine the QoS flow to be synchronized (ie, the first QoS flow) according to the indication information 5 or according to the first QoS flow marked in step 704. And, SMF+PGW-C can synchronize the QoS flow state according to one of the following three methods.
  • SMF+PGW-C can send indication information 6 to the UE to instruct the UE to delete the first bearer and/or the first QoS flow.
  • SMF+PGW-C can send the PCO in step 701 to the UE in step 710, 711 or 714, or SMF+PGW-C can complete the 5G system to 4G system interworking process (after step 715 and step After 717 (not shown in the figure), another PCO is sent to the UE.
  • the PCO can be sent separately or included in other process messages of the 4G system and sent to the UE.
  • the PCO message can instruct the UE to delete the first bearer and/or the first QoS flow.
  • the SMF+PGW-C can initiate a bearer modification process or a bearer release process. In the process or bearer release process, the UE is instructed to delete the first bearer and/or the first QoS flow.
  • step 713 is omitted. If step 713 is performed, step 709 is omitted, and the session establishment response in step 714 includes indication information 6.
  • SMF+PGW-C returns UE context information to AMF. If step 709 is executed, the terminal context information can carry indication information 6.
  • AMF sends UE context information to MME.
  • the context information may include indication information 6, for example, indication information 6 is carried in EPS bearer status (EPS bearer status) information.
  • the indication information 6 can also be sent to the MME separately.
  • the context information may include the first QoS flow marked by the AMF, for example, the first QoS flow marked by the AMF is carried in EPS bearer status (EPS bearer status) information.
  • the first QoS flow marked by the AMF can also be sent to the MME separately.
  • Steps 707-711 can be omitted when there is no N26 interface.
  • the MME sends a session establishment request to the SMF+PGW-C through the SGW (not shown in the figure).
  • the session establishment request in step 712 may include the indication information 5 sent by the UE.
  • step 713 The same operations as step 709.
  • step 709 can be omitted.
  • step 709 the PCO is carried in the message in steps 714-715.
  • SMF+PGW-C sends a session establishment response message to the MME.
  • the session establishment response message may include indication information 6.
  • the indication information 6 may be separate indication information, or information contained in the PCO. In this case, steps 717-718 are omitted.
  • the session establishment response message includes the PCO in step 701, and the PCO instructs the UE to delete the first bearer and/or the first QoS flow.
  • the MME sends an attach accept message or a TAU accept message to the terminal.
  • the attach accept message or the TAU accept message contains indication information 6.
  • the indication information 6 may be separate indication information or information contained in the PCO.
  • the attach accept message or the TAU accept message includes the PCO in step 701, and the PCO instructs the UE to delete the first bearer and/or the first QoS flow.
  • This step is optional.
  • step 709 If the method (2) in step 709 is executed, this step is omitted.
  • the UE can delete the first bearer and/or the first QoS flow according to the indication information 6. Alternatively, the UE initiates the bearer modification procedure according to the instruction information 6, and steps 716-717 are omitted at this time.
  • step 716 can be performed before or after step 717, and step 718 can be omitted (SMF+PGW -C has deleted the locally stored first bearer and/or first QoS flow in step 511 or step 504), or SMF+PGW-C deleted the local first bearer and/or first QoS flow in step 718 (SMF+PGW-C did not delete the locally stored first bearer and/or first QoS flow in step 511 and step 504).
  • the UE sends a PCO response message to SMF+PGW-C to notify SMF+PGW-C that the UE has confirmed the first bearer and/or first QoS flow to be deleted, or, the PCO response message is used to notify SMF +PGW-C
  • the UE has deleted the local first bearer and/or first QoS flow.
  • SMF+PGW-C can initiate a bearer modification process or a bearer release process, which is used to trigger the UE to delete the first bearer and/or the first bearer.
  • a QoS flow if SMF+PGW-C does not delete the first bearer and/or the first QoS flow in step 704 or step 709 or step 713, the first bearer and/or the first QoS flow may be deleted in step 718.
  • the specific process can refer to the existing agreement.
  • SMF+PGW-C may delete the local first bearer and/or the first QoS flow in step 718.
  • step 718 can be executed at any time after step 709. If step 709 is not executed and step 713 is executed, step 718 can be executed at any time after step 713.
  • SMF+PGW-C can also determine the data channel to be synchronized according to the following method. If SMF+PGW-C initiates the process of deleting QoS flows in the 5G system, SMF+PGW-C marks the process of deleting QoS flows initiated by it. When the UE completes the registration process of the 4G system, SMF+PGW-C will trigger Bearer modification process to synchronize the data channel of UE and SMF+PGW-C.
  • SMF+PGW-C records the identifier of the bearer that it initiates to delete QoS flows. If multiple QoS flow deletion procedures occur in the 4G network (each QoS flow deletion procedure can delete one or Multiple QoS flows), then SMF+PGW-C can be marked once or multiple times. If SMF+PGW-C is marked only once, only the first QoS flow deletion process or the last QoS flow deletion process can be marked. Subsequently, SMF+PGW-C can indicate that SMF+PGW-C will trigger a bearer modification procedure to synchronize the data channel of the UE and SMF+PGW-C.
  • the UE if the UE deletes the QoS flow, the UE records the deleted QoS flow. After the communication system is switched, the UE initiates a bearer modification process to synchronize the data channel with the core network element.
  • the foregoing embodiment mainly describes the method of SMF+PGW-C instructing the UE to synchronize.
  • the MME may also instruct the UE to synchronize. As shown in Figure 8.
  • This method is suitable for scenarios where the terminal device is switched from a 5G system to a 4G system, and the method can be suitable for situations with an N26 interface.
  • Steps 801-804 are the same as steps 701-704 and will not be described again.
  • the UE in the idle state switches from the 5G system to the 4G system, it sends a TAU request to the E-UTRAN.
  • the TAU request includes indication information 5.
  • the indication information 5 may indicate the EPS bearer status (EPS bearer status) and/or the QoS flow status (QoS flow status) on the UE.
  • the indication information 5 is the above The first state information described.
  • the above-mentioned indication information 5 may indicate the first QoS flow instead of all QoS flows local to the UE.
  • the UE may also use indication information 5 to indicate the EPS bearer status and/or QoS flow status on the UE at this time.
  • the UE may also send the above-mentioned indication information 5 to SMF+PGW-C through the PCO.
  • the E-UTRAN sends the UE's TAU request to the MME.
  • the TAU request includes indication information 5 sent by the UE.
  • the specific process can refer to the communication protocol (3GPP TS 23.502: "Procedures for the 5G System; Stage 2").
  • the MME sends a TAU accept message to the UE, and the message contains indication information 7.
  • the indication information 7 may directly instruct the UE to delete the first bearer and/or the first QoS flow, or the indication information 7 may also instruct the UE to initiate a bearer modification process or a bearer release process.
  • the UE After receiving the corresponding indication information, the UE deletes the first bearer and/or the first QoS flow, or initiates a bearer modification process or a bearer release process, so that the MME and SMF+PGW-C can synchronize the bearer.
  • the UE can initiate a bearer modification process, and notify SMF+PGW-C to delete the first bearer and/or the first QoS flow stored in SMF+PGW-C in the bearer modification process.
  • Fig. 11 shows a communication method provided by this application.
  • the method is described by taking a scenario where a terminal device switches from a 4G system to a 5G system as an example. In addition, it is also applicable to a scenario where a terminal device switches from a 5G system to a 4G system. Moreover, this method can be applied to the case of N26 interface and no N26 interface.
  • the method in FIG. 11 may be applicable to the case where the UE deletes the first bearer and/or the first QoS flow without notifying the network side.
  • the UE deletes the first EPS bearer, but due to reasons such as the UE being in an idle state or loss of wireless signals, the UE fails to notify the network side to delete the first EPS bearer, that is, the status of the first EPS bearer on the network side is actually pending UE synchronization.
  • the UE in the idle state switches from 4G to 5G, it sends a registration request to the NG-RAN. Since the UE deleted the first EPS bearer but failed to notify the network side to delete the first EPS bearer, the registration request includes indication information 5.
  • the indication information 5 may indicate the state of the first EPS bearer. In another possible implementation manner, the indication information 5 may indicate the status of each EPS bearer in the UE (that is, the aforementioned first status information) and/or the QoS flow status.
  • the NG-RAN sends the UE's registration request to the AMF, and the registration request contains the indication information 5 sent by the UE.
  • the specific process can refer to the communication protocol (3GPP TS 23.502: "Procedures for the 5G System; Stage 2").
  • AMF sends a session establishment request to SMF+PGW-C, and the session establishment request carries indication information 5 sent by the UE.
  • the indication information 5 may be included in the session establishment request message, or included in the PCO in the session establishment response message, or may also be included in other messages and sent to the UE.
  • SMF+PGW-C may determine the first bearer according to the indication information 5.
  • SMF+PGW-C may determine that the bearer indicated by indication information 1 is different from the local bearer of SMF+PGW-C as the first bearer.
  • SMF+PGW-C may determine that the bearer indicated by the indication information 5 is the first bearer.
  • steps 1106 and 1107 reference may be made to the description of S210 and S220 in FIG. 2, which will not be repeated here.
  • SMF+PGW-C sends a session establishment response message to AMF.
  • AMF sends a registration acceptance message to NG-RAN.
  • the NG-RAN sends a registration acceptance message to the UE.
  • Figure 12 shows another communication method provided by this application.
  • the method is described by taking a scenario where a terminal device switches from a 4G system to a 5G system as an example.
  • a terminal device switches from a 5G system to a 4G system.
  • this method can be applied to the case of N26 interface and no N26 interface.
  • the method in FIG. 11 is also applicable to the case where the SMF+PGW-C deletes the first bearer and/or the first QoS flow without notifying the UE.
  • SMF+PGW-C sends a bearer deletion request to the MME for requesting deletion of the first bearer.
  • the MME sends a bearer deletion response to SMF+PGW-C.
  • steps 1201 and 1202 reference may be made to the descriptions of 501 and 503 in FIG. 5, which will not be repeated here.
  • Step 1203. When the UE in the idle state switches from 4G to 5G, it sends a registration request to the NG-RAN. In other words, the UE initiates the 4G to 5G mobility registration process.
  • the NG-RAN sends the registration request of the UE to the AMF.
  • the AMF requests the UE context from the MME through the N26 interface.
  • the MME sends the context of the UE to the AMF.
  • Steps 1205 and 1206 are applicable to the scenario where the N26 interface is supported between the MME and AMF. When the N26 interface is not supported between MME and AMF, steps 1205 and 1206 are not executed.
  • the specific process can refer to the communication protocol (3GPP TS 23.502: "Procedures for the 5G System; Stage 2").
  • AMF sends a session establishment request to SMF+PGW-C.
  • SMF+PGW-C sends a session establishment response to AMF.
  • the session is established.
  • the response may include the above-mentioned correspondence between EBI and ARP.
  • the session establishment response includes EBI.
  • the EBI here can be understood as used to identify EPS bearers that are not deleted on the network side, or in other words, can be understood as used to identify EPS bearers that can be switched during interworking.
  • the AMF generates EPS bearer status information (ie, the aforementioned second status information).
  • the AMF may communicate with multiple SMF+PGW-Cs, and the AMF may generate EPS bearer status information according to the session establishment response received from each SMF+PGW-C.
  • the AMF may record in the EPS bearer status information the corresponding status of the EBI contained in the above-mentioned correspondence between EBI and ARP carried in the session establishment response message, for example, the character bit of the bearer identified by the EBI is recorded as a representation Values not deleted (for example, recorded as 1).
  • the AMF may generate EPS bearer status information according to the above EBI carried in the session establishment response message.
  • the AMF may also record in the EPS bearer status information the character bits of other bearers identified by the EBI not carried in the session establishment response message as a value indicating that it has been deleted (for example, recorded as 0).
  • the bearers identified by the EBI that are not carried in the session establishment response message are the bearers that have been deleted by the SMF+PGW-C, for example, include the aforementioned first bearer.
  • the EPS bearer status information recorded by the AMF includes the information of each EPS bearer associated with a PDN connection, and the first bearer that has been deleted by SMF+PGW-C is one of the EPS bearers associated with the PDN connection or Multiple bearers.
  • the AMF may not perform step 1210, and only determine the EBI included in the above-mentioned correspondence between EBI and ARP from the received session establishment response, or determine the EBI from the session establishment response.
  • steps 1209 and 1210 can also be replaced by the following step 1209':
  • SMF+PGW-C generates EPS bearer status information (that is, the aforementioned second status information), and sends a session establishment response carrying EPS bearer status information to AMF.
  • the manner in which SMF+PGW-C generates EPS bearer status information can refer to the manner in which AMF generates EPS bearer status information, which will not be repeated here.
  • the AMF sends a registration acceptance message to the RAN.
  • the registration acceptance message carries EPS bearer status information.
  • the registration acceptance message includes the EBI determined by the AMF.
  • the registration acceptance message may also include address information of the SMF+PGW-C corresponding to the EBI.
  • the RAN sends a registration acceptance message to the UE.
  • the registration acceptance message carries EPS bearer status information.
  • the registration acceptance message includes the EBI determined by the AMF.
  • the registration acceptance message may also include address information of the SMF+PGW-C corresponding to the EBI.
  • the UE synchronizes according to the received information.
  • the UE will compare the EPS bearer status information received from AMF with the locally stored EPS bearer status information. If it finds EPS bearers with different information, the UE will release the EPS bearer. And delete the QoS flow information (for example, QFI rules and QoS parameters) corresponding to the EPS bearer.
  • QoS flow information for example, QFI rules and QoS parameters
  • the UE checks whether the received EBI is included in the locally stored EPS bearer status information. If it does, the UE releases the EPS bearer and deletes the QoS flow information corresponding to the EPS bearer (for example, QFI rules and QoS parameters).
  • the communication device includes a hardware structure and/or software module corresponding to each function.
  • the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a certain function is executed by hardware or computer software-driven hardware depends on the specific application and design constraint conditions of the technical solution. Professionals and technicians can use different methods for each specific application to implement the described functions, but such implementation should not be considered beyond the scope of this application.
  • the present application may divide the communication device into functional units according to the foregoing method examples.
  • each function may be divided into each functional unit, or two or more functions may be integrated into one processing unit.
  • the above-mentioned integrated unit can be implemented in the form of hardware or software functional unit. It should be noted that the division of units in this application is illustrative, and is only a logical function division, and there may be other division methods in actual implementation.
  • Fig. 9 shows a schematic structural diagram of a communication device provided by the present application.
  • the communication device 900 may be used to implement the methods described in the foregoing method embodiments.
  • the communication device 900 may be a chip, a network device or a terminal device.
  • the communication device 900 includes one or more processors 901, and the one or more processors 901 can support the communication device 900 to implement the network equipment (session management network element or mobility management network element) in FIGS. 2 to 8 or FIG. 11, and FIG. Yuan) or terminal equipment.
  • the processor 901 may be a general-purpose processor or a special-purpose processor.
  • the processor 901 may be a central processing unit (CPU) or a baseband processor.
  • the baseband processor may be used to process communication data, and the CPU may be used to control a communication device (for example, a network device, a terminal device, or a chip), execute a software program, and process data of the software program.
  • the communication device 900 may further include a transceiving unit 905 to implement signal input (reception) and output (transmission).
  • the communication device 900 may be a chip, and the transceiver unit 905 may be the input and/or output circuit of the chip, or the transceiver unit 905 may be a communication interface of the chip, and the chip may be used as a terminal device or a network device or other wireless communication. Components of equipment.
  • the communication device 900 may include one or more memories 902, on which a program 904 is stored.
  • the program 904 can be run by the processor 901 to generate an instruction 903 so that the processor 901 executes the method described in the foregoing method embodiment according to the instruction 903.
  • the memory 902 may also store data.
  • the processor 901 may also read data stored in the memory 902. The data may be stored at the same storage address as the program 904, or the data may be stored at a different storage address from the program 904.
  • the processor 901 and the memory 902 may be provided separately or integrated together, for example, integrated on a single board or a system-on-chip (SOC).
  • SOC system-on-chip
  • the communication device 900 may further include a transceiver unit 905 and an antenna 906.
  • the transceiver unit 905 may be called a transceiver, a transceiver circuit or a transceiver, and is used to implement the transceiver function of the communication device through the antenna 906.
  • the processor 901 is used to execute:
  • processor 901 is used to execute:
  • the processor 901 may be a CPU, a digital signal processor (digital signal processor, DSP), an application specific integrated circuit (ASIC), a field programmable gate array (field programmable gate array, FPGA) or other programmable logic devices , For example, discrete gates, transistor logic devices, or discrete hardware components.
  • DSP digital signal processor
  • ASIC application specific integrated circuit
  • FPGA field programmable gate array
  • This application also provides a computer program product, which, when executed by the processor 901, implements the communication method described in any method embodiment in this application.
  • the computer program product may be stored in the memory 902, for example, a program 904, which is finally converted into an executable object file that can be executed by the processor 901 after preprocessing, compilation, assembly, and linking.
  • This application also provides a computer-readable storage medium on which a computer program is stored, and when the computer program is executed by a computer, the communication method described in any method embodiment in this application is implemented.
  • the computer program can be a high-level language program or an executable target program.
  • the computer-readable storage medium is, for example, the memory 902.
  • the memory 902 may be a volatile memory or a non-volatile memory, or the memory 902 may include both a volatile memory and a non-volatile memory.
  • the non-volatile memory can be read-only memory (ROM), programmable read-only memory (programmable ROM, PROM), erasable programmable read-only memory (erasable PROM, EPROM), and electrically available Erase programmable read-only memory (electrically EPROM, EEPROM) or flash memory.
  • the volatile memory may be random access memory (RAM), which is used as an external cache.
  • RAM random access memory
  • static random access memory static random access memory
  • dynamic RAM dynamic random access memory
  • synchronous dynamic random access memory synchronous DRAM, SDRAM
  • double data rate synchronous dynamic random access memory double data rate SDRAM, DDR SDRAM
  • enhanced synchronous dynamic random access memory enhanced SDRAM, ESDRAM
  • synchronous connection dynamic random access memory serial DRAM, SLDRAM
  • direct rambus RAM direct rambus RAM, DR RAM
  • FIG. 10 shows a schematic structural diagram of a terminal device provided in this application.
  • the terminal device 1000 can be applied to the system shown in FIG. 1 to realize the functions of the terminal device in the above-mentioned method embodiments of FIGS. 2 to 8 or FIGS. 11 and 12.
  • FIG. 10 only shows the main components of the terminal device.
  • the terminal device 1000 includes a processor, a memory, a control circuit, an antenna, and an input and output device.
  • the processor is mainly used to process the communication protocol and communication data, and to control the entire terminal device. For example, the processor receives the power saving signal through the antenna and the control circuit.
  • the memory is mainly used to store programs and data, such as storing communication protocols and data to be sent.
  • the control circuit is mainly used for the conversion of baseband signals and radio frequency signals and the processing of radio frequency signals.
  • the control circuit and the antenna together can also be called a transceiver, which is mainly used to send and receive radio frequency signals in the form of electromagnetic waves.
  • the input and output device is, for example, a touch screen or a keyboard, and is mainly used to receive data input by the user and output data to the user.
  • the processor can read the program in the memory, interpret and execute the instructions contained in the program, and process the data in the program.
  • the processor performs baseband processing on the information to be sent, and outputs the baseband signal to the radio frequency circuit.
  • the radio frequency circuit performs radio frequency processing on the baseband signal to obtain a radio frequency signal, and transmits the radio frequency signal to the antenna in the form of electromagnetic waves. Send outside.
  • the radio frequency circuit receives the radio frequency signal through the antenna, converts the radio frequency signal into a baseband signal, and outputs the baseband signal to the processor, and the processor converts the baseband signal into information And process the information.
  • FIG. 10 only shows one memory and one processor. In an actual terminal device, there may be multiple processors and multiple memories.
  • the memory may also be called a storage medium or a storage device, etc., which is not limited in this application.
  • the processor in FIG. 10 can integrate the functions of the baseband processor and the CPU.
  • the baseband processor and the CPU can also be independent processors, using technologies such as buses. interconnected.
  • the terminal device may include multiple baseband processors to adapt to different network standards, the terminal device may include multiple CPUs to enhance its processing capabilities, and the various components of the terminal device may be connected through various buses.
  • the baseband processor may also be referred to as a baseband processing circuit or a baseband processing chip.
  • the CPU may also be called a central processing circuit or a central processing chip.
  • the function of processing the communication protocol and the communication data may be built in the processor, or stored in the memory in the form of a program, and the processor executes the program in the memory to realize the baseband processing function.
  • the antenna and control circuit with the transceiver function can be regarded as the transceiver 1001 of the terminal device 1000, which is used to support the terminal device to implement the receiving function in the method embodiment, or to support the terminal device to implement the method embodiment.
  • the processor having the processing function is regarded as the processor 1002 of the terminal device 1000.
  • the terminal device 1000 includes a transceiver 1001 and a processor 1002.
  • the transceiver may also be referred to as a transceiver, transceiver device, and so on.
  • the device for implementing the receiving function in the transceiver 1001 can be regarded as a receiver, and the device for implementing the sending function in the transceiver unit 1001 can be regarded as a transmitter. That is, the transceiver 1001 includes a receiver and a transmitter. The receiver may also be called a receiver, an input port, a receiving circuit, etc., and the transmitter may be called a transmitter, an output port, a transmitting circuit, etc.
  • the processor 1002 may be used to execute programs stored in the memory to control the transceiver unit 1001 to receive signals and/or send signals, and complete the functions of the terminal device in the foregoing method embodiments.
  • the function of the transceiver unit 1001 may be implemented by a transceiver circuit or a dedicated chip for transceiver.
  • the disclosed system, device, and method may be implemented in other ways. For example, some features of the method embodiments described above may be ignored or not implemented.
  • the device embodiments described above are merely illustrative.
  • the division of units is only a logical function division. In actual implementation, there may be other division methods, and multiple units or components may be combined or integrated into another system.
  • the coupling between the units or the coupling between the components may be direct coupling or indirect coupling, and the foregoing coupling includes electrical, mechanical, or other forms of connection.
  • the size of the sequence number of each process does not mean the order of execution.
  • the execution order of each process should be determined by its function and internal logic, and should not correspond to the embodiments of the present application.
  • the implementation process constitutes any limitation.
  • system and “network” in this article are often used interchangeably in this article.
  • the term “and/or” in this article is only an association relationship describing associated objects, which means that there can be three types of relationships. For example, A and/or B can mean that there is A alone, and both A and B exist. There are three cases of B.
  • the character “/” in this text generally indicates that the associated objects before and after are in an "or” relationship.

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Abstract

本申请提供了一种适用于不同通信系统切换场景的通信方法，该方法包括：会话管理网元确定第一系统中的第一数据通道，第一数据通道为待与终端设备同步的数据通道；会话管理网元在终端设备从第一系统切换至第二系统的流程中同步以下中的至少一项：第一数据通道，或，第二系统中与第一数据通道对应的第二数据通道。由于会话管理网元在通信系统切换后执行了同步处理，使得会话管理网元存储的数据通道信息与终端设备存储的数据通道信息保持一致，从而避免了因通信系统切换后数据通道未同步导致的通信故障。

Description

通信方法和通信装置
本申请要求于2019年3月15日提交中国国家知识产权局、申请号为201910196769.8、申请名称为“通信方法和通信装置”的中国专利申请的优先权，其要求于2019年2月19日提交中国国家知识产权局、申请号为201910123361.8、申请名称为“通信方法和通信装置”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
本申请涉及通信领域，尤其涉及一种通信方法和通信装置。
背景技术
随着通信技术的发展，新的通信系统会逐渐取代旧的通信系统，但这一替代过程往往需要若干年时间。也就是说，新旧通信系统会在较长的一段时间内共存，因此，确保新旧通信系统之间的正常切换就成为一个不容忽视的问题。
以第四代(the 4 th generation，4G)通信系统和第五代(the 5 th generation，5G)共存的场景为例，核心网网元和终端设备可能需要从4G通信系统切换至5G通信系统，也可能需要从5G通信系统切换至4G通信系统。由于终端设备与核心网网元并不总能保持通信正常，例如，终端设备处于空闲态或者发生通信故障时无法接收到核心网网元发送的消息，因此，终端设备和核心网设备在切换通信系统后可能会发生通信失败的情况。如何提高通信系统切换时的可靠性是当前急需解决的问题。
发明内容
本申请提供了一种通信方法，可以应用于4G通信系统和5G通信系统共存的场景。应用该方法的通信设备通过确定通信系统切换流程中需要同步的数据通道并执行同步处理，使得通信系统切换后各个通信设备保存的数据通道信息一致，从而避免了通信系统切换后可能会发生通信失败的情况。
第一方面，提供了一种通信方法，包括：会话管理网元确定第一系统中的第一数据通道，第一数据通道为待与终端设备同步的数据通道；会话管理网元在终端设备从第一系统切换至第二系统的流程中同步以下中的至少一项：第一数据通道，或，第二系统中与第一数据通道对应的第二数据通道。例如，第一数据通道为终端设备已经删除但是没有通知网络侧的数据通道。
会话管理网元可以在通信系统切换前确定需要与终端设备同步的数据通道，也可以在通信系统切换过程中确定需要与终端设备同步的数据通道。随后，会话管理网元在通信系统切换的流程中执行同步处理，删除本地存储的第一数据通道和/或第二数据通道的信息，或者，指示终端设备删除第一数据通道和/或第二数据通道的信息，完成数据通道的同步处理。上述方案使得通信系统切换后各个通信设备保存的数据通道信 息一致，避免了通信系统切换后可能会发生通信失败的情况。
在一种可能的实现方式中，会话管理网元确定第一系统中的第一数据通道，包括：会话管理网元接收第一状态信息，第一状态信息用于指示终端设备中的数据通道的状态；会话管理网元根据第一状态信息确定所述第一数据通道。
会话管理网元可以对比本地存储的数据通道信息和由第一状态信息指示的终端设备存储的数据通道信息，该两个数据通道信息中不一致的信息所对应的数据通道即为第一数据通道。由于其它核心网网元保存的数据通道信息是从会话管理网元获取的信息，可能得不到及时更新，因此，上述方案能够避免其它核心网网元确定待同步的数据通道可能出现的错误。
在一种可能的实现方式中，会话管理网元确定第一系统中的第一数据通道，包括：会话管理网元向终端设备发送协议配置选项PCO；当会话管理网元收到不携带PCO的响应消息时，会话管理网元确定第一数据通道。
PCO是会话管理网元与终端设备之间的专用信息，其它网元仅透传PCO，因此，若会话管理网元未接收到包含PCO的响应消息，则说明会话管理网元与终端设备之间的通信出现问题，在此之前会话管理网元删除的数据通道在终端设备侧可能未被删除，因此，会话管理网元可以依据上述方案确定第一数据通道。由于上述方案未增加新的信息，因此，应用该方案确定第一数据通道能够更好地兼容现有技术。
在一种可能的实现方式中，所述PCO包括第一数据通道的信息或第二数据通道的信息中的至少一项。
会话管理网元也可以通过PCO明确指示终端设备需要同步的数据通道，其它核心网网元仅需透传该PCO，无需解析PCO，从而减小了其它核心网网元的负载。
在一种可能的实现方式中，会话管理网元确定第一系统中的第一数据通道，包括：会话管理网元向第一系统中的移动性管理网元发送第一消息，第一消息用于指示删除一个或多个数据通道；该会话管理网元从第一系统中的移动性管理网元接收第二消息，第二消息用于指示第一消息未通知到终端设备；会话管理网元根据第二消息将所述一个或多个数据通道确定为第一数据通道。
在一种可能的实现方式中，会话管理网元在所述终端设备从第一系统切换至第二系统流程中同步以下中的至少一项：第一数据通道，或，第二系统中与第一数据通道对应的第二数据通道；包括：
会话管理网元触发会话修改流程，会话修改流程用于同步以下中的至少一项：第一数据通道，或，第二系统中与第一数据通道对应的第二数据通道；或者，
会话管理网元在协议数据单元PDU会话激活过程中或PDN连接激活过程中触发以下中的至少一项的同步：第一数据通道，或，第二系统中与第一数据通道对应的第二数据通道。
上述方案为会话管理网元的同步处理提供了多种可选方式，具有较高的灵活性。
在一种可能的实现方式中，会话管理网元在终端设备从第一系统切换至第二系统的流程中同步以下中的至少一项：第一数据通道，或，第二系统中与第一数据通道对应的第二数据通道；包括：会话管理网元删除第一数据通道的信息或第二数据通道的信息中的至少一项；
其中，当第一系统为4G系统，第二系统为5G系统时，第一数据通道的信息包括演进的分组系统EPS承载的信息，第二数据通道的信息包括与EPS承载关联的QoS流的信息；或者，
当第一系统为5G系统，第二系统为4G系统时，第一数据通道的信息包括QoS流的信息，第二数据通道的信息包括与QoS流关联的EPS承载的信息。
第二方面，本申请还提供了一种通信方法，包括：第二系统中的移动性管理网元确定第一系统中的第一数据通道，该第一数据通道为待与终端设备同步的数据通道；第二系统中的移动性管理管理网元在终端设备从第一系统切换至第二系统的流程中同步以下中的至少一项：第一数据通道，或，第二系统中与第一数据通道对应的第二数据通道。
第二系统中的移动性管理网元为通信系统切换后与终端设备通信的移动性管理网元。第二系统中的该移动性管理网元确定需要与终端设备同步的数据通道。随后，该移动性管理网元执行同步处理，删除本地存储的第一数据通道和/或第二数据通道的信息，或者，指示终端设备删除第一数据通道和/或第二数据通道的信息，完成数据通道的同步处理。上述方案使得通信系统切换后各个通信设备保存的数据通道信息一致，避免了通信系统切换后可能会发生通信失败的情况。
在一种可能的实现方式中，第二系统中的移动性管理网元确定第一系统中的第一数据通道，包括：第二系统中的移动性管理网元从终端设备接收第一状态信息，第一状态信息用于指示终端设备的数据通道的状态；第二系统中的移动性管理网元从第一系统中的移动性管理网元接收第二状态信息，第二状态信息用于指示终端设备的数据通道的状态；第二系统中的移动性管理网元根据第一状态信息和第二状态信息确定第一数据通道。
数据通道不同步的原因可能是原通信系统(即，第一系统)中终端设备与核心网网元之间的删除数据通道的信息交互过程出现问题，因此，第二系统中的移动性管理网元可以对比第一系统中的移动性管理网元存储的数据通道信息和终端设备存储的数据通道信息，该两个数据通道信息中不一致的信息所对应的数据通道即为第一数据通道。上述方案无需会话管理网元执行，减小了会话管理网元的负担。
在一种可能的实现方式中，所述方法还包括：第二系统中的移动性管理网元向会话管理网元发送第一状态信息，第一状态信息用于第一数据通道的确定。
第二系统中的移动性管理网元也可以向会话管理网元发送第一状态信息，以便于会话管理网元对比该会话管理网元存储的数据通道信息和终端设备存储的数据通道信息，该两个数据通道信息中不一致的信息所对应的数据通道即为第一数据通道。由于其它核心网网元保存的数据通道信息是从会话管理网元获取的信息，可能得不到及时更新，因此，上述方案能够避免其它核心网网元确定待同步的数据通道可能出现的错误。
第三方面，本申请还提供了一种通信方法，包括：终端设备确定第一系统中的第一数据通道，第一数据通道为待与会话管理网元同步的数据通道；终端设备在从第一系统切换至第二系统的流程中同步以下中的至少一项：第一数据通道，或，第二系统中与所述第一数据通道对应的第二数据通道。
终端设备可以在通信系统切换前确定需要与会话管理网元同步的数据通道，也可以在通信系统切换过程中确定需要与会话管理网元同步的数据通道。随后，终端设备在通信系统切换的流程中执行同步处理，删除本地存储的第一数据通道和/或第二数据通道的信息，或者，通知会话管理网元删除第一数据通道和/或第二数据通道的信息，完成数据通道的同步处理。上述方案使得通信系统切换后各个通信设备保存的数据通道信息一致，避免了通信系统切换后可能会发生通信失败的情况。
在一种可能的实现方式中，终端设备确定第一系统中的第一数据通道，包括：终端设备向会话管理网元发送通知消息，该通知消息用于通知会话管理网元终端设备删除了一个或多个数据通道；终端设备根据未收到通知消息的响应消息将所述一个或多个数据通道确定为第一数据通道。
终端设备可以发起删除数据通道的流程，若终端设备未收到通信消息的响应消息，则说明终端设备与会话管理网元之间的通信出现问题，终端设备准备删除或者已删除的数据通道未被会话管理网元删除，终端设备可以确定上述准备删除或者已删除的数据通道为待同步的数据通道，即，第一数据通道。
在一种可能的实现方式中，所述方法还包括：终端设备向会话管理网元发送第一状态信息，第一状态信息指示终端设备中的数据通道的状态，第一状态信息用于第一数据通道的确定。
终端设备可能由于处于空闲态而未收到会话管理网元发送的删除数据通道的消息，终端设备可以主动向会话管理网元发送第一状态信息，或者，终端设备可以根据核心网网元的请求发送第一状态信息，以便于会话管理网元确定是否需要同步数据通道。
可选地，终端设备确定第一系统中的第一数据通道，包括：终端设备向所述会话管理网元发送第一PCO；当终端设备收到不携带第一PCO的响应消息时，终端设备确定第一数据通道。
PCO是会话管理网元与终端设备之间的专用信息，其它网元仅透传PCO，因此，若会话管理网元未接收到包含第一PCO的响应消息，则说明会话管理网元与终端设备之间的通信出现问题，在此之前会话管理网元删除的数据通道在终端设备侧可能未被删除，因此，会话管理网元可以依据上述方案确定第一数据通道。由于上述方案未增加新的信息，因此，应用该方案确定第一数据通道能够更好地兼容现有技术。
在一种可能的实现方式中，所述第一PCO包括第一数据通道的信息或第二数据通道的信息中的至少一项。
终端设备也可以通过第一PCO明确通知会话管理网元需要同步的数据通道，其它核心网网元仅需透传第一PCO，无需解析第一PCO，从而减小了其它核心网网元的负载。
可选地，终端设备确定第一系统中的第一数据通道，包括：终端设备接收第二状态信息，第二状态信息用于指示会话管理网元中的数据通道的状态；终端设备根据第二状态信息确定第一数据通道。
终端设备还可以对比本地存储的数据通道信息和由上述第二状态信息指示的会话管理网元存储的数据通道信息，该两个数据通道信息中不一致的信息所对应的数据通道即为第一数据通道。由于移动性管理网元保存的数据通道信息是从终端设备或者会 话管理网元获取的信息，可能得不到及时更新，因此，上述方案能够避免移动性管理网元确定待同步的数据通道可能出现的错误。
在一种可能的实现方式中，终端设备在从第一系统切换至第二系统的流程中同步以下中的至少一项：第一数据通道，或，第二系统中与第一数据通道对应的第二数据通道；包括：终端设备删除第一数据通道的信息或第二数据通道的信息中的至少一项；
其中，当第一系统为4G系统，第二系统为5G系统时，第一数据通道的信息包括EPS承载的信息，第二数据通道的信息包括与EPS承载关联的QoS流的信息；或者
当第一系统为5G系统，第二系统为4G系统时，第一数据通道的信息包括QoS流的信息，第二数据通道的信息包括与QoS流关联的EPS承载的信息。
在一种可能的实现方式中，所述PCO的响应消息用于指示所述终端设备已删除待删除的数据通道，或者，所述PCO的响应消息用于指示所述终端设备已确定删除待删除的数据通道，或者，所述PCO的响应消息用于指示所述终端设备已接收到所述PCO消息。
可选地，所述终端设备从所述会话管理网元接收PCO；所述终端设备向所述会话管理网元发送所述PCO的响应消息，所述PCO的响应消息不包括任何参数，或者，所述PCO包括所述第一数据通道的信息或所述第二数据通道的信息中的至少一项。
PCO是会话管理网元与终端设备之间的专用信息，其它网元仅透传PCO，因此，终端设备和会话管理网元之间通过PCO确定待删除的数据通道，有利于提高同步数据通道的效率。
在一种可能的实现方式中，所述PCO的响应消息用于指示所述终端设备已删除待删除的数据通道，或者，所述PCO的响应消息用于指示所述终端设备已确定删除待删除的数据通道，或者，所述PCO的响应消息用于指示所述终端设备已接收到所述PCO消息。
第四方面，本申请还提供了一种通信方法，包括：终端设备确定所述终端设备已经在第一系统中删除但没有通知网络侧的第一数据通道；所述终端设备向会话管理网元发送第一状态信息，所述第一状态信息指示所述终端设备中的数据通道的状态，该第一状态信息用于所述第一数据通道的确定。例如，所述终端设备向移动性管理网元发送第一消息，所述第一消息中包括所述第一状态信息，其中，所述第一消息为附着请求消息、注册请求消息、或会话建立请求消息。上述方案使得通信系统切换后各个通信设备保存的数据通道信息一致，避免了通信系统切换后可能会发生通信失败的情况。
第五方面，本申请还提供了一种通信方法，包括：会话管理网元删除第一系统中的第一数据通道，所述第一数据通道为待与终端设备同步的数据通道；所述会话管理网元向第二系统中的移动性管理网元发送数据通道的信息，其中，所述数据通道的信息包括数据通道的标识信息，或者，数据通道的标识信息与分配和保留优先级之间的对应关系(例如，可参考图12中步骤1209的描述)。上述方案使得通信系统切换后各个通信设备保存的数据通道信息一致，避免了通信系统切换后可能会发生通信失败的情况。
第六方面，本申请还提供了一种通信方法，包括：第二系统中的移动性管理网元 从会话管理网元接收数据通道的信息，其中，所述数据通道的信息包括数据通道的标识信息，或者，数据通道的标识信息与分配和保留优先级之间的对应关系(例如，可参考图12中步骤1209的描述)；所述移动性管理网元根据所述数据通道的信息确定状态信息(例如，可参考图12中步骤1210的描述)；所述移动性管理网元向所述终端设备发送所述状态信息(例如，可参考图12中步骤1211至1213的描述)，所述状态信息用于所述终端设备侧对于以下中至少一项的同步：第一数据通道，或，所述第二系统中与第一数据通道对应的第二数据通道。所述第一数据通道为待与终端设备同步的数据通道。上述方案使得通信系统切换后各个通信设备保存的数据通道信息一致，避免了通信系统切换后可能会发生通信失败的情况。
第七方面，本申请还提供了一种通信方法，包括：终端设备从第二系统中的移动性管理网元接收状态信息(例如，可参考图12中步骤1211和1212的描述)；所述终端设备根据所述状态信息确定第一数据通道，所述第一数据通道为待与终端设备同步的数据通道；所述终端设备同步以下中的至少一项：所述第一数据通道，或，所述第二系统中与所述第一数据通道对应的第二数据通道(例如，可参考图12中步骤1213的描述)。例如，终端设备删除所述第一数据通道的信息或所述第二数据通道的信息中的至少一项；其中，当所述第一系统为4G系统，所述第二系统为5G系统，所述第一数据通道的信息包括演进的分组系统EPS承载的信息，所述第二数据通道的信息包括与所述EPS承载关联的QoS流的信息；或者当所述第一系统为5G系统，所述第二系统为4G系统，所述第一数据通道的信息包括QoS流的信息，所述第二数据通道的信息包括与所述QoS流关联的EPS承载的信息。上述方案使得通信系统切换后各个通信设备保存的数据通道信息一致，避免了通信系统切换后可能会发生通信失败的情况。
第八方面，本申请提供了一种通信装置，该通信装置可以是会话管理网元，也可以是会话管理网元内的芯片。该通信装置可以包括处理单元和收发单元。当该装置是会话管理网元时，该处理单元可以是处理器，该收发单元可以是通信接口；该会话管理网元还可以包括存储单元，该存储单元可以是存储器；该存储单元用于存储指令，该处理单元执行该存储单元所存储的指令，以使该会话管理网元执行第一方面或第五方面所述的方法。当该装置是会话管理网元内的芯片时，该处理单元可以是处理器，该收发单元可以是输入/输出接口、管脚或电路等；该处理单元执行存储单元所存储的指令，以使该会话管理网元执行第一方面或第五方面所述的方法，该存储单元可以是该芯片内的存储单元(例如，寄存器、缓存等)，也可以是该会话管理网元内的位于该芯片外部的存储单元(例如，只读存储器、随机存取存储器等)。
第九方面，本申请提供了另一种通信装置，该装置可以是移动性管理网元，也可以是移动性管理网元内的芯片。该装置可以包括处理单元和收发单元。当该装置是移动性管理网元时，该处理单元可以是处理器，该收发单元可以是通信接口；该移动性管理网元还可以包括存储单元，该存储单元可以是存储器；该存储单元用于存储指令，该处理单元执行该存储单元所存储的指令，以使该移动性管理网元执行第二方面或第六方面所述的方法。当该装置是移动性管理网元内的芯片时，该处理单元可以是处理器，该收发单元可以是输入/输出接口、管脚或电路等；该处理单元执行存储单元所存储的指令，以使该移动性管理网元执行第二方面或第六方面所述的方法，该存储单元 可以是该芯片内的存储单元(例如，寄存器、缓存等)，也可以是该移动性管理网元内的位于该芯片外部的存储单元(例如，只读存储器、随机存取存储器等)。
第十方面，本申请提供了再一种通信装置，该装置可以是终端设备，也可以是终端设备内的芯片。该装置可以包括处理单元和收发单元。当该装置是终端设备时，该处理单元可以是处理器，该收发单元可以是收发器；该终端设备还可以包括存储单元，该存储单元可以是存储器；该存储单元用于存储指令，该处理单元执行该存储单元所存储的指令，以使该终端设备执行第三方面、第四方面或第七方面所述的方法。当该装置是终端设备内的芯片时，该处理单元可以是处理器，该收发单元可以是输入/输出接口、管脚或电路等；该处理单元执行存储单元所存储的指令，以使该终端设备执行第三方面、第四方面或第七方面所述的方法，该存储单元可以是该芯片内的存储单元(例如，寄存器、缓存等)，也可以是该终端设备内的位于该芯片外部的存储单元(例如，只读存储器、随机存取存储器等)。
第十一方面，本申请提供了一种计算机可读存储介质，该计算机可读存储介质中存储了计算机程序，该计算机程序被处理器执行时，使得处理器执行第一方面或第五方面所述的方法。
第十二方面，本申请提供了一种计算机可读存储介质，该计算机可读存储介质中存储了计算机程序，该计算机程序被处理器执行时，使得处理器执行第二方面或第六方面所述的方法。
第十三方面，本申请提供了一种计算机可读存储介质，该计算机可读存储介质中存储了计算机程序，该计算机程序被处理器执行时，使得处理器执行第三方面、第四方面或第七方面所述的方法。
第十四方面，本申请提供了一种计算机程序产品，该计算机程序产品包括：计算机程序代码，当该计算机程序代码被处理器运行时，使得处理器执行第一方面或第五方面所述的方法。
第十五方面，本申请提供了一种计算机程序产品，该计算机程序产品包括：计算机程序代码，当该计算机程序代码被处理器运行时，使得处理器执行第二方面或第六方面所述的方法。
第十六方面，本申请提供了一种计算机程序产品，该计算机程序产品包括：计算机程序代码，当该计算机程序代码被处理器运行时，使得处理器执行第三方面、第四方面或第七方面所述的方法。
第十七方面，本申请还提供了一种通信方法，包括：会话管理网元向终端设备发送删除消息和PCO，所述删除消息用于指示待删除的数据通道；所述会话管理网元根据接收到所述PCO的响应消息确定所述终端设备已删除所述待删除的数据通道，或者，确定所述终端设备已确定删除所述待删除的数据通道，或者，确定所述终端设备已接收到所述删除消息。
PCO是会话管理网元与终端设备之间的专用信息，其它网元仅透传PCO，因此，终端设备和会话管理网元之间通过PCO确定待删除的数据通道，有利于提高同步数据通道的效率。
在一种可能的实现方式中，所述PCO包含所述待删除的数据通道的信息。
第十八方面，本申请还提供了一种通信方法，包括：终端设备从会话管理网元接收删除消息和PCO，所述删除消息用于指示待删除的数据通道；所述终端设备向所述会话管理网元发送所述PCO的响应消息，所述PCO的响应消息用于指示所述终端设备已删除所述待删除的数据通道，或者，所述PCO的响应消息用于指示所述终端设备已确定删除所述待删除的数据通道，或者，所述PCO的响应消息用于指示所述终端设备已接收到所述删除消息。
PCO是会话管理网元与终端设备之间的专用信息，其它网元仅透传PCO，因此，终端设备和会话管理网元之间通过PCO确定待删除的数据通道，有利于提高同步数据通道的效率。
可选地，所述PCO包含所述待删除的数据通道的信息。
第十九方面，本申请提供了一种通信装置，该装置可以是会话管理网元，也可以是会话管理网元内的芯片。该装置可以包括处理单元和收发单元。当该装置是会话管理网元时，该处理单元可以是处理器，该收发单元可以是通信接口；该会话管理网元还可以包括存储单元，该存储单元可以是存储器；该存储单元用于存储指令，该处理单元执行该存储单元所存储的指令，以使该会话管理网元执行第十七方面所述的方法。当该装置是会话管理网元内的芯片时，该处理单元可以是处理器，该收发单元可以是输入/输出接口、管脚或电路等；该处理单元执行存储单元所存储的指令，以使该会话管理网元执行第十七方面所述的方法，该存储单元可以是该芯片内的存储单元(例如，寄存器、缓存等)，也可以是该会话管理网元内的位于该芯片外部的存储单元(例如，只读存储器、随机存取存储器等)。
第二十方面，本申请提供了另一种通信装置，该装置可以是终端设备，也可以是终端设备内的芯片。该装置可以包括处理单元和收发单元。当该装置是终端设备时，该处理单元可以是处理器，该收发单元可以是收发器；该终端设备还可以包括存储单元，该存储单元可以是存储器；该存储单元用于存储指令，该处理单元执行该存储单元所存储的指令，以使该终端设备执行第十八方面所述的方法。当该装置是终端设备内的芯片时，该处理单元可以是处理器，该收发单元可以是输入/输出接口、管脚或电路等；该处理单元执行存储单元所存储的指令，以使该终端设备执行第十八方面所述的方法，该存储单元可以是该芯片内的存储单元(例如，寄存器、缓存等)，也可以是该终端设备内的位于该芯片外部的存储单元(例如，只读存储器、随机存取存储器等)。
第二十一方面，本申请提供了一种计算机可读存储介质，该计算机可读存储介质中存储了计算机程序，该计算机程序被处理器执行时，使得处理器执行第十七方面所述的方法。
第二十二方面，本申请提供了一种计算机可读存储介质，该计算机可读存储介质中存储了计算机程序，该计算机程序被处理器执行时，使得处理器执行第十八方面所述的方法。
第二十三方面，本申请提供了一种计算机程序产品，该计算机程序产品包括：计算机程序代码，当该计算机程序代码被处理器运行时，使得处理器执行第十七方面所述的方法。
第二十四方面，本申请提供了一种计算机程序产品，该计算机程序产品包括：计算机程序代码，当该计算机程序代码被处理器运行时，使得处理器执行第十八方面所述的方法。
附图说明
图1是一种适用于本申请实施例的网络架构的示意图；
图2是本申请提供的一种通信方法的示意图；
图3是本申请提供的另一种通信方法的示意图；
图4是本申请提供的再一种通信方法的示意图；
图5是本申请提供的再一种通信方法的示意图；
图6是本申请提供的再一种通信方法的示意图；
图7是本申请提供的再一种通信方法的示意图；
图8是本申请提供的再一种通信方法的示意图；
图9是本申请提供的一种通信装置的示意图；
图10是本申请提供的一种终端设备的示意图；
图11是本申请提供的再一种通信方法的示意图；
图12是本申请提供的再一种通信方法的示意图。
具体实施方式
下面将结合附图，对本申请中的技术方案进行描述。首先介绍适用于本申请的场景。
本申请实施例适用于第一系统和第二系统互通的场景。例如，图1是一种适用于本申请实施例的网络架构，该网络架构包括4G通信系统和5G通信系统。下面，对该网络架构中涉及的主要网元进行说明。
4G通信系统(以下，简称为“4G系统”)可以包括以下网元。
1、(无线)接入网络(radio access network，(R)AN)网元：用于为特定区域的授权终端设备提供入网功能，并能够根据终端设备的级别，业务的需求等使用不同质量的传输隧道。
(R)AN网元能够管理无线资源，为终端设备提供接入服务，进而完成控制信号和终端设备数据在终端设备和核心网之间的转发，(R)AN网元也可以理解为传统网络中的基站。在4G通信系统中，(R)AN网元也可以称为演进型通用陆基无线接入网(evovled universal terrestrial radio access network，E-UTRAN)或演进型基站(eNB)，如图1中所示。
需要说明的是，上述“网元”也可以称为实体、设备、装置或模块等，本申请并未特别限定。并且，在本申请中，为了便于理解和说明，在对部分描述中省略“网元”这一描述，例如，将(R)AN网元简称RAN，此情况下，该“(R)AN网元”应理解为(R)AN网元网元或(R)AN实体，以下，省略对相同或相似情况的说明。
2、移动性管理实体(mobility management entity，MME)，用于提供移动性管理的功能。此外，MME还可以提供合法监听以及接入授权/鉴权等功能。
3、服务网关(serving gateway，SGW)，用于提供用户数据转发等功能。
4、分组数据网络网关用户面功能(packet data network gateway user function，PGW-U)，用于提供PDN网关的用户面功能。
5、分组数据网络网关控制面功能(packet data network gateway control function，PGW-C)，用于提供PDN网关的控制面功能。
6、策略和计费规则功能(policy and charging rules function，PCRF)，用于提供指导网络行为的统一策略框架，为控制面功能网元提供策略规则信息等。
7、归属签约用户服务器(home subscriber server，HSS)，包括用户配置文件，用于执行用户的身份验证和授权，并可提供有关用户物理位置的信息。
5G通信系统(以下，简称为“5G系统”)可以包括以下网元。
1、(R)AN网元：用于为特定区域的授权终端设备提供入网功能，并能够根据终端设备的级别，业务的需求等使用不同质量的传输隧道。
在5G通信系统中，(R)AN网元也可以称为下一代接入网(next generation radio access network，NG-RAN，如图1所示)或下一代基站(gNB)。
2、接入管理功能(access and mobility management function，AMF)，用于接入管理和移动性管理的功能。此外，AMF还可以提供合法监听以及接入授权/鉴权等功能。
在一种可能的设计中，AMF可以通过N26接口与MME进行通信。在图1中，各个网元之间连线附件的字母和数字表示各个网元之间的通信接口的名称，然而，各个网元之间的通信接口还可以具有其他名称，本申请在此并不限制。
3、用户面功能(user plane function，UPF)，用于分组路由和转发以及用户面数据的服务质量(quality of service，QoS)处理等。
4、会话管理功能(session management function，SMF)，主要用于会话管理、终端设备的网络互连协议(internet protocol，IP)地址分配和管理、选择和管理用户平面功能。此外，SMF还可以是策略控制和收费功能接口的终结点。
5、策略控制功能(policy control function，PCF)，用于指导网络行为的统一策略框架，为控制面功能网元(例如AMF、SMF等)提供策略规则信息等。
6、统一数据管理(unified data management，UDM)网元，用于管理签约数据。此外，还用于用户服务注册管理、处理终端设备标识，接入鉴权等。
上述网络架构中，功能相同或相近的网元可以联合设置。例如，UPF和PGW-U可以合设，SMF和PGW-C可以合设，PCF和PCRF可以合设，HSS和UDM可以合设，图1中的“+”即表示两个设备可以联合设置。
应理解，上述应用于本申请的网络架构仅是举例说明的从服务化架构的角度描述的网络架构，适用本申请实施例的网络架构并不局限于此，任何能够实现上述各个网元的功能的网络架构都适用于本申请实施例。
上述网元或者功能既可以是硬件设备中的网络元件，也可以是在专用硬件上运行软件功能，或者是平台(例如，云平台)上实例化的虚拟化功能。
终端设备可以从4G通信系统中切换至5G通信系统，或者，也可以从5G通信系统中切换至4G通信系统。终端设备可以包括各种具有无线通信功能的手持设备、车 载设备、可穿戴设备、计算设备或连接到无线调制解调器的其它处理设备，以及各种形式的终端，移动台(mobile station，MS)，终端(terminal)，用户设备(user equipment，UE)，软终端等等。例如，水表、电表、传感器等。
在本申请中，终端设备或上述任一网络设备包括硬件层、运行在硬件层之上的操作系统层，以及运行在操作系统层上的应用层。该硬件层例如包括中央处理器(central processing unit，CPU)、内存管理单元(memory management unit，MMU)和内存(也称为主存)等硬件。该操作系统可以是任意一种或多种通过进程(process)实现业务处理的计算机操作系统，例如，Linux操作系统、Unix操作系统、Android操作系统、iOS操作系统或windows操作系统等。该应用层包含浏览器、通讯录、文字处理软件、即时通信软件等应用。并且，本申请实施例并未对本申请实施例提供的方法的执行主体的具体结构特别限定，只要能够通过运行记录有本申请提供的方法的代码的程序，以根据本申请提供的方法进行通信即可，例如，本申请实施例提供的方法的执行主体可以是终端设备或网络设备，或者，是终端设备或网络设备中能够调用程序并执行程序的功能模块。
需要说明的是，在本申请实施例中，在应用层可以运行多个应用程序，此情况下，执行本申请实施例的方法的应用程序与用于控制接收端设备完成所接收到的数据所对应的动作的应用程序可以是不同的应用程序。
下面，将详细介绍本申请提供的基于上述网络架构的通信方法。
本申请提供的通信方法涉及多个网元，不同的网元对应不同的处理步骤，但这些步骤均为基于一个发明思想的不同实施方式，为了清楚地介绍每个网元的改进之处，首先将从不同网元的角度描述本申请提供的通信方法。
图2是从会话管理网元的角度描述的本申请提供的一种通信方法，该方法200包括：
S210，会话管理网元确定第一系统中的第一数据通道，该第一数据通道为待与终端设备同步的数据通道。
上述会话管理网元可以是图1中的SMF+PGW-C。第一系统为4G系统或5G系统，当第一系统为4G系统时，第一数据通道为第一演进的分组系统(evolved packet system，EPS)承载(bearer)；当第一系统为5G系统时，第一数据通道为第一QoS流。
在本申请中。“第一”、“第二”等词语仅表示同一类型的事物中的不同个体，除此之外并无其它限定。例如，第一数据通道表示一个或多个数据通道，第一系统和第二系统表示两个不同的通信系统。
在通信系统工作的过程中，会话管理网元与终端设备可能会由于一些原因导致二者存储的数据通道信息不同。
例如，在第一种情况下，当会话管理网元在第一系统中删除了第一数据通道并指示终端设备删除该数据通道时，终端设备处于空闲态(idle)或者出现通信故障，则终端设备在第一系统中无法接收到会话管理网元发送的消息。因此，终端设备没有删除第一数据通道，从而导致会话管理网元与终端设备保存的数据通道信息不一致，这可能导致通信系统切换后会话管理网元与终端设备之间的通信出现问题。
在第二种情况下，若终端设备在第一系统中删除了第一数据通道但未成功通知会 话管理网元，同样可能导致通信系统切换后会话管理网元与终端设备之间的通信出现问题。
需要说明的是，在本申请中，“数据通道”可以与“数据通道信息”等价。例如，删除数据通道可以被解释为：删除数据通道信息，该数据通道信息即该数据通道对应的参数或者配置信息。
为了确保通信系统切换后的正常通信，会话管理网元首先需要确定第一数据通道，即，待与终端设备同步的数据通道，也可以称为需要与终端设备同步的数据通道。对于上述第一种情况，待与终端设备同步的数据通道就是指网络侧没有成功通知终端设备删除的数据通道。对于上述第二种情况，待与终端设备同步的数据通道就是指终端设备已经删除但没有通知网络侧的数据通道。以第二种情况为例进行举例说明，当终端设备切换前位于4G系统，待与终端设备同步的数据通道就是终端设备已经删除但是没有通知网络侧的EPS承载。
例如，会话管理网元可以通过多种方法确定第一数据通道。下面，举出会话管理网元确定第一数据通道的几个例子。
示例一。
会话管理网元可以从终端设备获取第一状态信息。例如，终端设备向MME或AMF发送第一状态信息，MME或AMF收到后将该第一状态信息发送给会话管理网元。该第一状态信息用于指示终端设备中的数据通道的状态。例如，终端设备发送的附着请求(attach request)消息、注册请求(registration request)消息、或会话建立请求消息中可以携带该第一状态信息。
会话管理网元可以根据第一状态信息确定第一数据通道。例如，会话管理网元同样保存有数据通道的状态信息，会话管理网元从MME或者AMF获取第一状态信息后，可以将两个状态信息进行比对，状态信息不一致的数据通道即为第一数据通道。
示例二。
会话管理网元向终端设备发送协议配置选项(protocol configuration options，PCO)，该PCO可以包括第一数据通道的信息和/或第二数据通道的信息，也可以不包含任何信息。其中，第二数据通道是第二系统中与第一数据通道对应的数据通道。例如，当第一数据通道为承载时，第二数据通道为该承载映射的QoS流；当第一数据通道为QoS流时，第二数据通道为该QoS流映射的承载。
上述PCO用于指示终端设备删除第一数据通道和/或第二数据通道。其中，PCO为终端设备和会话管理网元之间传递信息的参数，其作用类似于容器(container)，能够承载不同的信息。在传输过程中，终端设备和会话管理网元之外的网元不会解析PCO中的内容。
若会话管理网元发送的PCO未送达终端设备，则终端设备也不会回应PCO。因此，会话管理网元可以依据接收到不包含PCO的响应消息确定第一数据通道，即，确定会话管理网元发送的PCO对应的数据通道为所述第一数据通道。
其中，会话管理网元发送的PCO可以和终端设备发送的PCO关联，关联的方法可以是：通过PCO信元包头中的标识参数匹配。例如，会话管理网元发送的PCO信元包头携带字段a，终端设备发送的PCO相应消息中PCO信元包头携带字段b，字段 a与字段b相同，或者，字段a与字段b具有关联关系。本申请对上述两个PCO的关联方法不做限定。
会话管理网元发送的PCO可以承载于不同的消息中，本申请对承载PCO的消息不作限定。例如，终端设备从4G系统向5G系统切换时，承载PCO的消息可以是删除承载请求；终端设备从5G系统向4G系统切换时，承载PCO的消息可以是AMF的服务化消息或NAS消息等。
示例三。
会话管理网元向MME或者AMF发送第一消息，该第一消息携带一个或多个数据通道的信息，用于指示终端设备删除该一个或多个数据通道。若会话管理网元从MME或者AMF收到第二消息，该第二消息用于指示第一消息未通知到终端设备，则会话管理网元确定该一个或多个数据通道为第一数据通道。
当终端设备从4G系统向5G系统切换时，上述第一消息可以是删除承载请求。相应地，上述第二消息可以是删除承载响应，该删除承载响应包括指示第一消息未通知到终端设备的指示信息，本申请对该指示信息的具体形式不作限定。
当终端设备从5G系统向4G系统切换时，上述第一消息可以是AMF的服务化消息或NAS消息等。相应地，上述第二消息可以是删除承载响应，该删除承载响应包括指示第一消息未通知到终端设备的指示信息，本申请对该指示信息的具体形式不作限定。
上述示例为会话管理网元主动确定第一数据通道的例子，会话管理网元主动确定第一数据通道后，可以向其它核心网网元(例如，MME和AMF)发送第一指示信息，该第一指示信息用于指示第一数据通道，以便于其它核心网网元同步本地的数据通道。
会话管理网元还可以根据其它网元发送的指示信息确定第一数据通道。如下列例子所示。
示例四。
会话管理网元从移动性管理网元接收第二指示信息，该第二指示信息指示第一数据通道，这样，会话管理网元无需主动确定第一数据通道，减轻了会话管理网元的负担。移动性管理网元确定第一数据通道的方法将在下文中详细描述。
会话管理网元确定第一数据通道后，可以执行下列步骤。
S220，会话管理网元在终端设备从第一系统切换至第二系统的流程中同步以下中的至少一项：第一数据通道，或，第二系统中与第一数据通道对应的第二数据通道。
同步第一数据通道和第二数据通道的目的在于使得会话管理网元和终端设备存储的数据通道信息相同。
针对上述第一种情况，若会话管理网元删除了第一数据通道而未通知给终端设备，则会话管理网元在S220中指示终端设备删除第一数据通道。其中，会话管理网元可以在标记第一数据通道后立即删除第一数据通道，待能够与终端设备正常通信后再指示终端设备删除第一数据通道；会话管理网元也可以在标记第一数据通道后保留第一数据通道，待指示终端设备删除第一数据通道后再删除第一数据通道。
上述第一种情况的具体操作将结合后面的图5和图7进一步描述。
针对上述第二种情况，若终端设备删除了第一数据通道而未通知给会话管理网元， 在一种可能的实现方式中，会话管理网元在S220中删除本地存储的第一数据通道的信息或第二系统中与第一数据通道对应的第二数据通道的信息中的至少一项。例如，当第一系统为4G系统，并且第二系统为5G系统时，第一数据通道的信息包括演进的分组系统(evolved packet system，EPS)承载的信息，第二数据通道的信息包括与该EPS承载关联的QoS流的信息。EPS承载的信息可以是EPS承载的标识或EPS承载的QoS参数。QoS流的信息可以是Qos规则或QoS参数。或者，当第一系统为5G系统，并且第二系统为4G系统时，第一数据通道的信息包括QoS流的信息，第二数据通道的信息包括与该QoS流关联的EPS承载的信息。
针对上述第二种情况，或者，在另一种可能的实现方式中，会话管理网元可以在终端设备从第一系统切换至第二系统的过程中触发会话修改流程，该会话修改流程用于同步第一数据通道和/或第二数据通道。为同步5G通信系统的QoS流，上述会话修改流程可以是协议数据单元(protocol data unit，PDU)会话修改流程，也可以是PDU会话释放流程或PDU会话去激活流程；为同步4G通信系统的承载，上述会话修改流程还可以是承载修改流程或承载去激活流程。
针对上述第二种情况，在又一种可能的实现方式中，也可以结合上述两种实现方式，即，会话管理网元可以释放第一数据通道，并删除本地存储的第二数据通道的信息。以终端设备从4G通信系统切换到5G通信系统为例，SMF可以释放之前终端设备没有成功通知网络侧删除的EPS承载，并删掉本地存储的与该EPS承载对应的QoS流的QoS规则和QoS参数。
上述第二种情况的具体操作将结合后面的图11进一步描述。
因此，根据本申请实施例所述的方法，通信系统切换后各个通信设备保存的数据通道信息一致，避免了通信系统切换后可能会发生通信失败的情况。
上文从会话管理网元的角度介绍了本申请提供的通信方法，此外，结合图2中上述步骤S210中示例一的描述，本申请还公开了一种终端设备执行的通信方法。该方法包括：终端设备确定该终端设备已经在第一系统中删除但没有通知网络侧的第一数据通道；该终端设备向会话管理网元发送第一状态信息，该第一状态信息指示所述终端设备中的数据通道的状态，该第一状态信息用于第一数据通道的确定。
例如，终端设备向MME或AMF发送第一状态信息，MME或AMF收到后将该第一状态信息发送给会话管理网元。例如，终端设备发送的附着请求消息、注册请求消息、或会话建立请求消息中可以携带该第一状态信息。会话管理网元收到第一状态信息后，可以根据第一状态信息确定第一数据通道。
下面，将从移动性管理网元的角度描述本申请提供的通信方法。
与会话管理网元类似，移动性管理网元也存储有数据通道信息。因此，当终端设备存储的数据通道信息与移动性管理网元存储的数据通道信息不同时，移动性管理网元也需要进行同步处理。例如，移动性管理网元可以根据图3所示的方法300执行下列步骤。
S310，第二系统中的移动性管理网元确定第一系统中的第一数据通道，该第一数据通道为待与终端设备同步的数据通道。
第一系统、第二系统和第一数据通道的含义与方法200中相应的名词的含义相同， 在此不再赘述。当第二系统为4G系统时，第二系统中的移动性管理网元为MME；当第二系统为5G系统时，第二系统中的移动性管理网元为AMF。
移动性管理网元可以主动确定第一数据通道，可选地，移动性管理网元在确定第一数据通道后还可以指示会话管理网元。移动性管理网元也可以等待会话管理网元的指示，根据会话管理网元的指示确定第一数据通道。下面，分别对上述情况进行说明。
情况一，移动性管理网元主动确定第一数据通道。
第二系统中的移动性管理网元从终端设备接收第一状态信息，第一状态信息用于指示终端设备的数据通道的状态；第二系统中的移动性管理网元从第一系统中的移动性管理网元接收第二状态信息，第二状态信息用于指示终端设备的数据通道的状态；第二系统中的移动性管理网元根据第一状态信息和第二状态信息确定所述第一数据通道。
上述两个状态信息是不同网元存储的数据通道信息，第二系统中的移动性管理网元可以比对该两个状态信息所指示的数据通道的状态，并确定状态不同的数据通道为第一数据通道。
例如，当终端设备从4G系统切换至5G系统时，第二系统中的移动性管理网元为AMF，AMF可以通过N26接口从MME获取第二状态信息，并且，AMF可以通过N1接口获取第一状态信息，从而可以确定第一数据通道。
可选地，AMF可以向会话管理网元发送第二指示信息，指示第二数据通道，从而减轻了会话管理网元的负担。
又例如，当终端设备从5G系统切换至4G系统时，第二系统中的移动性管理网元为MME，MME可以通过N26接口从AMF获取第二状态信息，并且，AMF可以通过E-UTRAN从终端设备获取第一状态信息，从而可以确定第一数据通道。
可选地，MME可以向会话管理网元发送第二指示信息，指示第二数据通道，从而减轻了会话管理网元的负担。
情况二，移动性管理网元根据会话管理网元的指示确定第一数据通道。
第二系统中的移动性管理网元可以从会话管理网元接收第一指示信息，第一指示信息用于指示第一数据通道，从而移动性管理网元可以确定第一数据通道。会话管理网元确定第一数据通道的方法如方法200所述，在此不再赘述。
无论第二系统中的移动性管理网元确定第一数据通道的方法属于情况一还是情况二，该移动性管理网元均可以向会话管理网元发送所述第一状态信息，以便于会话管理网元确定第一数据通道。
第二系统中的移动性管理网元在确定第一数据通道后可以执行下列步骤。
S320，第二系统中的移动性管理管理网元在终端设备从第一系统切换至第二系统的流程中同步以下中的至少一项：第一数据通道，或，第二系统中与第一数据通道对应的第二数据通道。
例如，会话管理网元可以触发PDU会话修改流程或PDU会话释放流程，AMF可以在PDU会话修改流程或PDU会话释放流程中同步第一数据通道和/或第二数据通道；会话管理网元可以触发承载修改流程或承载去激活流程，MME可以在承载修改流程或承载去激活流程中同步第一数据通道和/或第二数据通道。
移动性管理网元也可以在会话管理网元触发的PDU会话激活流程中同步第一数据通道和/或第二数据通道。
可选地，所述第二系统中的移动性管理网元也可以主动发起同步流程，例如，第二系统中的移动性管理网元在终端设备从第一系统切换至第二系统后向第二系统的会话管理网元发起会话修改流程，所述会话修改流程用于同步以下中的至少一项：第一数据通道，或，第二系统中与第一数据通道对应的第二数据通道。
上述会话修改流程可以是PDU会话修改流程，也可以是PDU会话释放流程，还可以是承载修改流程或承载去激活流程。
此外，第二系统中的移动性管理网元也可以通过会话删除流程同步第一数据通道和/或第二数据通道。
上文从核心网网元的角度介绍了本申请提供的通信方法，下面，将从终端设备的角度描述本申请提供的通信方法。
与核心网网元类似，终端设备也存储有数据通道信息。因此，当终端设备存储的数据通道信息与核心网网元存储的数据通道信息不同时，终端设备也需要进行同步处理。例如，终端设备可以根据图4所示的方法400执行下列步骤。
S410，终端设备确定第一系统中的第一数据通道，第一数据通道为待与会话管理网元同步的数据通道。
第一系统、第二系统和第一数据通道的含义与方法200中相应的名词的含义相同，在此不再赘述。
终端设备确定第一数据通道的方式可以有以下几种。
方式一。
终端设备存在待同步的数据通道可能是由于终端设备未接收到核心网网元发送的删除第一数据通道的消息。例如，终端设备处于空闲态或者出现通信故障。此时，终端设备可以根据核心网网元的指示确定第一数据通道，具体可参见方法200和方法300中的实施例。也就是说，在方式一中，待与会话管理网元同步的数据通道，也可以称为需要与会话管理网元同步的数据通道。例如，待与会话管理网元同步的数据通道就是指会话管理网元已经删除但没有通知终端设备的数据通道。
为了避免上述情况导致的通信问题，在一种可能的实现方式中，终端设备可以在通信系统切换过程中向核心网网元发送第一状态信息，该第一状态信息指示终端设备中的数据通道的状态，以便于核心网网元根据第一状态信息确定需要同步的数据通道(即，第一数据通道)。
或者，在另一种可能的实现方式中，终端设备也可以根据接收到的第二状态信息确定第一数据通道，第二状态信息用于指示会话管理网元中的数据通道的状态。这将结合图12进一步描述。例如，终端设备可以在通信系统切换后或者在通信系统切换过程中主动请求获取该第二状态信息。
方式二。
终端设备存在待同步的数据通道也可能是由于终端设备主动删除了第一数据通道但未成功通知核心网网元。例如，终端设备向会话管理网元发送通知消息，该通知消息用于通知会话管理网元终端设备删除了一个或多个数据通道；若终端设备未收到上 述通知消息的响应消息，则终端设备可以将所述一个或多个数据通道确定为第一数据通道。
方式三。
终端设备还可以按照下列方式获取第一数据通道。终端设备向会话管理网元发送PCO，若终端设备未收到该PCO的响应消息，或者，终端设备收到的响应消息中不包含PCO，说明终端设备与会话管理网元之间的通信出现问题，终端设备可以确定之前删除的一个或多个数据通道为第一数据通道。可选地，终端设备发送的该PCO包括第一数据通道的信息和第二数据通道的信息中的至少一项。
终端设备确定第一数据通道后可以执行下列步骤。
S420，终端设备在从第一系统切换至第二系统的流程中同步以下中的至少一项：第一数据通道，或，第二系统中与第一数据通道对应的第二数据通道。
若终端设备删除了第一数据通道而未通知核心网网元，则终端设备在S420中可以通知核心网网元(例如，会话管理网元)删除第一数据通道或第二数据通道的信息中的至少一项。其中，终端设备可以在标记第一数据通道后立即删除第一数据通道，待能够与核心网网元正常通信后再通知核心网网元删除第一数据通道；终端设备也可以在标记第一数据通道后保留第一数据通道，待通知核心网网元删除第一数据通道后再删除第一数据通道。
若核心网网元删除了第一数据通道而未通知给终端设备，在一种可能的实现方式中，终端设备在S420中删除本地存储的第一数据通道的信息或第二数据通道的信息中的至少一项。第一数据通道的信息或第二数据通道的信息可参考图2中的描述，此处不再赘述。
在另一种可能的实现方式中，终端设备从第一系统切换至第二系统的过程中可以在核心网网元触发的会话修改流程中释放第一数据通道，该会话修改流程用于同步第一数据通道和/或第二数据通道。类似的，上述会话修改流程可以是PDU会话修改流程，也可以是PDU会话释放流程，还可以是承载修改流程或承载去激活流程。
例如，当终端设备从4G系统切换到5G系统后，会话管理网元可以触发会话修改流程或会话释放流程，在此流程中终端设备同步第一数据通道和/或第二数据通道；当终端设备从5G系统切换到4G系统后，会话管理网元可以触发承载修改流程或承载去激活流程，在此流程中终端设备同步第一数据通道和/或第二数据通道。
终端设备也可以在会话管理网元发起的终端设备从第一系统切换至第二系统后触发PDU会话去激活流程中，同步第一数据通道和/或第二数据通道。
终端设备也可以发起会话修改流程同步第一数据通道和/或第二数据通道。
可选地，在S420中，终端设备删除第一数据通道的信息或第二数据通道的信息中的至少一项。
其中，当第一系统为4G系统，并且第二系统为5G系统时，第一数据通道的信息包括演进的EPS承载的信息，第二数据通道的信息包括与该EPS承载关联的QoS流的信息；或者，
当第一系统为5G系统，并且第二系统为4G系统时，第一数据通道的信息包括QoS流的信息，第二数据通道的信息包括与该QoS流关联的EPS承载的信息。
上述QoS流的信息可以是QoS流的Qos规则或QoS参数。
在又一种可能的实现方式中，也可以结合上述两种实现方式，即，终端设备可以释放第一数据通道，并删除本地存储的第二数据通道的信息。以终端设备从4G通信系统切换到5G通信系统为例，终端设备可以释放之前网络侧没有成功通知终端设备删除的EPS承载，并删掉本地存储的与该EPS承载对应的QoS流的QoS规则和QoS参数。
图5示出了本申请提供的一种通信方法。该方法以终端设备从4G系统切换至5G系统的场景为例进行描述，此外，也适用于终端设备从5G系统切换至4G系统的场景。并且，该方法可以适用于有N26接口和无N26接口的情况。图5的方法可以适用于SMF+PGW-C删除了第一承载和/或第一QoS流而未通知到UE的情况。
如图5所示，该方法包括如下步骤：
501.在4G网络中SMF+PGW-C向MME发送删除承载请求(delete bearer request)，用于请求删除第一承载，其中，第一承载可以是一个或多个承载。该消息可以包含一个PCO，该PCO可以指示UE删除第一承载和/或第一承载所映射的QoS流(即，第一QoS流)。例如，删除第一承载可以理解为删除第一承载对应的参数。删除第一QoS流可以理解为删除第一QoS流对应的QoS流标识(QoS flow identifier，QFI)和QoS规则。
若无线信号丢失或UE处于空闲态，则MME无法将删除承载请求发送至UE。
503.MME向SMF+PGW-C发送删除承载响应(delete bearer response)。
可选的，MME可以根据删除承载请求删除本地的第一承载的信息，或者，也可以对第一承载进行标记，待后续步骤再删除。
505.处于空闲态的UE从4G向5G切换时，向NG-RAN发送注册请求(registration request)。也就是说，UE发起4G到5G的移动性注册流程。
506.NG-RAN将UE的注册请求发送至AMF。
509.4G到5G移动性注册部分流程，具体过程可以参考通信协议(3GPP TS 23.502:"Procedures for the 5G System；Stage 2")。
510.AMF向SMF+PGW-C发送会话建立请求。
在图5的方法中，SMF+PGW-C可以根据不同方法确定未通知到UE的待删除承载。后续当UE向5G系统切换时，SMF+PGW-C可以通过多种方式指示UE删除上述待删除承载以及该承载映射的QoS流。
例如，SMF+PGW-C可以根据如下任一方法确定未通知到UE的待删除承载(即，第一承载)。
方法a:上述步骤505和506中发送的注册请求中携带指示信息1。指示信息1可以指示UE上的EPS承载状态(EPS bearer status)和/或QoS流状态(Qos flow status)，此时，指示信息1即前文所述的第一状态信息。上述步骤510中的会话建立请求携带UE发送的指示信息1。例如，指示信息1包含在会话建立请求消息中，或者，包含在会话建立请求消息中的PCO中，或者，也可以包含在其他消息中发送给UE。SMF+PGW-C收到会话建立请求后，可以根据指示信息1确定第一承载。例如，SMF+PGW-C可以确定指示信息1指示的承载与SMF+PGW-C本地的承载相异的承载 即为第一承载。
方法b(适用于AMF与MME之间存在N26接口):在MME收到步骤501的删除承载请求后并发现无法连接到UE，MME可以在步骤502中标记第一承载。例如，无法连接到UE可能的原因为:无线信号丢失或UE进入空闲态等。例如，MME可以存储第一承载的标识。MME也可以通过其它方法标记第一承载。例如，MME将第一承载的标识与特定字段进行绑定或映射；或者，MME对第一承载的上下文中的部分字段进行修改；或者，MME记录或存储未发送至UE的承载ID。本申请对MME标记第一承载的方法不作限定。
AMF收到步骤506的注册请求后，在步骤507中通过N26接口从MME请求获取UE的上下文。之后，在步骤508中，MME向AMF发送UE的上下文。在一种可能的实现方式中，该上下文可以包含指示信息2，指示信息2用于指示MME所标记的第一承载。例如，指示信息2可以承载于上下文的EPS承载状态中。可选地，在另一种可能的实现方式中，MME也可以单独将上述指示信息2发送至AMF，本发明对指示信息2的具体形式和发送方式均不做限定。AMF从MME获取到指示信息2后，会通过步骤510的会话建立请求将指示信息2发送至SMF+PGW-C。
SMF+PGW-C可以根据指示信息2确定第一承载。由于指示信息2所指示的承载是MME标记的承载，因此，指示信息2指示的承载即为第一承载。
因此，图5中的步骤502、507、508为可选步骤。
方法c(适用于AMF与MME之间存在N26接口):结合上述方式a和方式c，也就是说，步骤510的会话建立请求同时携带指示信息1和指示信息2，那么，SMF+PGW-C可以综合指示信息1和指示信息2确定第一承载，以免遗漏需要同步的承载。
方法d:SMF+PGW-C接收到步骤503中删除承载响应后，即可在步骤504中确定第一承载需要被同步。
例如，MME可以选择执行下列三种处理方式中的一种，使得SMF+PGW-C在步骤504中能够确定第一承载需要被同步。
MME可以在删除承载响应中添加第一承载的标识，SMF+PGW-C接收到该删除承载响应后，即可确定第一承载需要被同步。
MME也可以直接发送删除承载响应，由于MME未连接到UE，因此，该删除承载响应不包含UE发送的PCO，SMF+PGW-C接收到不包含PCO的响应消息后，即可确定删除承载请求中的第一承载需要被同步。
MME还可以向SMF+PGW-C发送单独的指示信息或原因值(cause)，该原因值可以使用现有技术中RAN原因值或非接入层(non access stratum，NAS)原因值，也可以使用新的原因值。
可选的，SMF+PGW-C还可以将方法d和上述方法a、b、c中任一项结合，来确定第一承载需要被同步。
此外，SMF+PGW-C在确定需要被同步的第一承载后，可以标记第一承载，例如，SMF+PGW-C可以存储第一承载的标识。
SMF+PGW-C标记第一承载的方法可以参考MME标记第一承载的方法。 SMF+PGW-C可以在标记第一承载后删除第一承载和/或第一QoS流，也可以将第一承载和第一QoS流保留至同步后再删除。若步骤504中SMF+PGW-C未删除第一承载和/或第一QoS流，则可以在后面的步骤511或步骤517中删除第一承载和/或第一QoS流。
当然，本申请并不限于上述几种方法，SMF+PGW-C也可以通过其他方法确定需要被同步的第一承载。之后，如图5所示，该方法包括：
511.SMF+PGW-C指示UE同步承载状态。
例如，SMF+PGW-C可以按照下列三种方法中的一种指示UE同步承载状态。
(1)SMF+PGW-C发起会话修改流程，即步骤517。步骤517可以在步骤511之后任何时间执行。其中，会话修改流程可以是PDU会话修改流程，也可以是PDU会话释放流程。另外，在该方式中，在步骤512中，SMF+PGW-C向AMF发送会话建立响应消息。在步骤513中，AMF向NG-RAN发送注册接受(registration accept)消息。514.NG-RAN向UE发送注册接受消息。
(2)SMF+PGW-C在步骤512中的会话建立响应消息中携带指示信息3，相应的，步骤513和514中的注册接受消息中携带该指示信息3。该指示信息3用于指示UE同步承载状态。例如，该指示信息3指示UE删除第一承载和/或第一QoS流。例如，该指示信息3可以是包含在会话建立响应消息中，或者，包含在会话建立响应消息中的PCO中，或者，也可以包含在其他消息中发送给UE。
UE收到指示信息3后，在步骤515中，UE可以根据指示信息3删除本地的第一承载和/或第一QoS流，或者UE也可以根据指示信息3发起会话修改流程，删除本地的第一承载和/或第一QoS流。
(3)SMF+PGW-C可以在步骤512-514中发送步骤501中的PCO；或者，在完成4G到5G的互通流程(位于步骤514之后以及步骤516之前，图中未画出)后，SMF+PGW-C再向UE发送一个PCO。该PCO可以单独发送，也可以是包含在5G其它流程消息中发送给UE。该PCO消息中指示UE删除第一承载和/或第一QoS流，当UE向SMF+PGW-C返回PCO响应消息后，SMF+PGW-C可以发起会话修改流程，在会话修改流程中UE删除第一承载和/或第一QoS流。其中，步骤515可以在步骤516发送响应消息之前或之后进行，此时SMF+PGW-C在接收到PCO响应后确认UE已删除或已确认待删除的第一承载和/或第一QoS流。若SMF+PGW-C在步骤511和步骤504中未删除本地存储的第一承载和/或第一QoS流，则可在步骤517中删除第一承载和/或第一QoS流。
或者，UE可以在SMF+PGW-C发起的会话修改流程(步骤517)中删除第一承载和/或第一QoS流，若SMF+PGW-C在步骤511和步骤504中未删除本地存储的第一承载和/或第一QoS流，则可在步骤517中删除第一承载和/或第一QoS流。
以下将结合上述步骤511中三种指示UE同步承载状态的方法详细如下步骤：
512.SMF+PGW-C向AMF发送会话建立响应消息。
可选地，SMF+PGW-C执行步骤511中的方法(2)，则会话建立响应消息包含指示信息3。该指示信息3可以是单独的指示信息，也可以是包含在PCO中的信息。若发送指示信息3，则步骤516-517不执行。
可选地，SMF+PGW-C执行步骤511中的方法(3)，发送包含步骤501中PCO的会话建立响应消息，PCO指示UE删除该第一承载和/或第一QoS流。
513.AMF向NG-RAN发送注册接受消息(registration accept)。
可选地，若SMF+PGW-C执行步骤511中的方法(2)，则该注册接受消息包含指示信息3。该指示信息3可以是单独的指示信息，也可以是承载于PCO中的信息。
可选地，若SMF+PGW-C执行步骤511中的方法(3)，则该注册接受消息包含步骤501中PCO，该PCO指示UE删除该第一承载和/或第一QoS流。
514.NG-RAN向UE发送注册接受消息。
可选地，若SMF+PGW-C执行步骤511中的方法(2)，则该注册接受消息包含指示信息3。该指示信息3可以是单独的指示信息，也可以是承载于PCO中的信息。
可选地，若SMF+PGW-C执行步骤511中的方法(3)，则该注册接受消息包含步骤501中PCO，该PCO指示UE删除该第一承载和/或第一QoS流。
515.该步骤为可选的步骤。
若SMF+PGW-C执行步骤511中的方法(1)，则步骤515不执行。
若SMF+PGW-C执行步骤511中的方法(2)，则UE根据指示信息3删除第一承载和/或第一QoS流。或者，UE根据指示信息3发起会话修改流程，此时步骤516-517省略。
若SMF+PGW-C执行步骤511中的方法(3)，且UE可以直接删除本地的第一承载和/或第一QoS流，则步骤515可在步骤516之前或之后进行，步骤517可省略(SMF+PGW-C在步骤511或步骤504中已删除本地存储的第一承载和/或第一QoS流)，或者，SMF+PGW-C在步骤517中删除本地的第一承载和/或第一QoS流(SMF+PGW-C在步骤511和步骤504中未删除本地存储的第一承载和/或第一QoS流)。
若SMF+PGW-C执行步骤511中的方法(3)，且UE需要在SMF+PGW-C发起的会话修改流程中删除本地的第一承载和/或第一QoS流，则步骤515不执行。
516.UE向SMF+PGW-C发送PCO响应消息，该PCO响应消息用于通知SMF+PGW-C该UE已确认待删除的第一承载和/或第一QoS流，或，该PCO响应消息用于通知SMF+PGW-C该UE已删除了本地的第一承载和/或第一QoS流。
517.该步骤为可选的步骤。
若SMF+PGW-C执行步骤511中的方法(3)，SMF+PGW-C会在收到步骤516的PCO响应消息后发起会话修改流程，该会话修改流程用于触发UE删除第一承载和/或第一QoS流。其中，若SMF+PGW-C未在步骤504或步骤511种删除第一承载和/或第一QoS流，可以在步骤517中删除第一承载和/或第一QoS流。具体流程可参考现有协议。
若UE已删除了本地的第一承载和/或第一QoS流，且SMF+PGW-C未在步骤504或步骤511删除第一承载和/或第一QoS流，则SMF+PGW-C在步骤517中删除本地的第一承载和/或第一QoS流。
若SMF+PGW-C执行步骤511中的方法(1)，步骤517可以在步骤511之后任何时间执行。
图5所示的方法为SMF+PGW-C确定待同步的数据通道的方法，可选地，SMF+PGW-C还可以按照下列方法确定待同步的数据通道。若SMF+PGW-C在4G系统中发起删除承载流程，则SMF+PGW-C标记其发起的承载删除流程，当UE完成5G系统的注册流程后，SMF+PGW-C将触发会话修改流程，以同步UE和SMF+PGW-C的数据通道。
例如，在步骤501前或步骤501后，SMF+PGW-C记录其是否发起过承载删除流程，若在4G网络中发生多次承载删除流程(每次承载删除流程可以删除一个或多个承载)，则SMF+PGW-C可标记一次或多次。若SMF+PGW-C仅标记一次，则可以仅标记第一次承载删除流程或最后一次承载删除流程。随后，SMF+PGW-C可以触发会话修改流程，以同步UE和SMF+PGW-C的数据通道。
类似地，若UE删除了承载，则UE记录已删除的承载，待通信系统切换完成后，UE发起会话修改流程与核心网网元进行数据通道同步处理。
上述实施例主要描述了SMF+PGW-C指示UE进行同步的方法，可选地，AMF也可以指示UE进行同步。如图6所示。
该方法同样以终端设备从4G系统切换至5G系统的场景为例进行描述，此外，也适用于终端设备从5G系统切换至4G系统的场景。并且，该方法可以适用于有N26接口的情况。图6的方法也适用于SMF+PGW-C删除了第一承载和/或第一QoS流而未通知到UE的情况。
步骤601-603和605-609可参考图5中步骤501-503和505-509的描述，不再赘述。
类似的，AMF可以根据如下任一方法确定未通知到UE的待删除承载(即，第一承载)。
方法e:步骤605和606中发送的注册请求中携带上述指示信息1。AMF可以根据指示信息1确定第一承载。例如，AMF可以确定指示信息1指示的承载与AMF本地的承载相异的承载即为第一承载。
方法f:在MME收到步骤601的删除承载响应后并发现无法连接到UE，MME可以在步骤602中标记第一承载。AMF收到步骤606的注册请求后，在步骤607中通过N26接口从MME请求获取UE的上下文。之后，在步骤608中，MME向AMF发送UE的上下文。在一种可能的实现方式中，该上下文可以包含上述指示信息2。AMF可以根据指示信息2确定第一承载。由于指示信息2所指示的承载是MME标记的承载，因此，指示信息2指示的承载即为第一承载。
方法g:结合上述方式e和方式f，也就是说，AMF可以综合指示信息1和指示信息2确定第一承载，以免遗漏需要同步的承载步骤。例如，AMF可以首先确定指示信息1指示的承载与AMF本地的承载相异的承载即为第一承载的候选承载，再结合指示信息2确定第一承载，以免遗漏需要同步的承载。
610.AMF向UE发送注册接受消息。该注册接受消息携带指示信息4，用于指示UE同步第一承载。例如，指示信息4可以指示UE删除第一承载和/或第一QoS流。
611.NG-RAN将AMF发送的指示信息4转发至UE。其中，指示信息4可以直接指示UE删除第一承载和/或第一QoS流，或者，指示信息4也可以指示UE发起会话修改流程。
612.UE接收到相应的指示信息后，删除第一承载和/或第一QoS流，或者，发起会话修改流程，以便于AMF和SMF+PGW-C同步承载。
上述实施例主要描述了UE从4G系统向5G系统切换时的通信方法，下面，将结合图7和图8描述UE从5G系统向4G系统切换时的通信方法。
图7所示的方法适用于UE从5G系统向4G系统切换的场景，并且，适用于有N26接口和无N26接口的场景。UE处于5G系统时，SMF+PGW-C可以根据不同方法标记待删除但未通知到UE的数据通道(即，第一QoS流)。后续当UE向4G系统切换时，SMF+PGW-C可以通过多种方式指示终端删除第一QoS流以及第一QoS流映射的承载。
如图7所示，该方法包括如下步骤：
701.SMF+PGW-C通过5G系统向AMF发送AMF的服务化消息，指示AMF删除第一QoS流。第一QoS流可以是一个或多个QoS流。该AMF的服务化消息可以包含一个PCO，该PCO可以指示UE删除第一QoS流和/或第一承载所映射的承载(即，第一承载)。例如，删除第一QoS流对应的参数，以及，删除第一QoS流对应的EPS承载标识(EPS bearer identifier，EBI)等参数。
若UE处于空闲态，则会话修改消息无法被发送至UE。
702.AMF可以根据AMF的服务化消息删除本地的承载信息。或者，由于发现无法连接到UE(可能的原因为:无线信号丢失，UE进入空闲态等)，AMF可以先在本步骤中标记第一QoS流，例如，AMF可以存储第一QoS流的标识，待后续步骤再删除。
AMF也可以通过其它方法标记第一QoS流，例如，AMF将第一QoS流的标识与特定字段进行绑定或映射；或者，AMF对第一QoS流的上下文中的部分字段进行修改。本申请对AMF标记第一QoS流的方法不作限定。
703.AMF向SMF+PGW-C发起会话修改请求并获取响应消息。可选地，AMF可以通知SMF+PGW-C第一QoS流未被UE删除，通知方法如下所示。
AMF可以在会话修改请求中添加第一QoS流的标识，SMF+PGW-C接收到该会话修改请求后，即可确定第一QoS流需要被同步。
AMF也可以直接发送会话修改请求，由于AMF未连接到UE，因此，该会话修改请求不包含UE发送的PCO，SMF+PGW-C接收到不包含PCO的响应消息后，即可确定服务化请求中的第一QoS流需要被同步。
AMF还可以向SMF+PGW-C发送单独的指示信息或原因值(cause)，该原因值可以使用现有技术中RAN原因值或非接入层(non access stratum，NAS)原因值，也可以使用新的原因值。
704.SMF+PGW-C在接收到AMF的会话修改请求后，可以标记第一QoS流，例如，SMF+PGW-C可以存储第一QoS流的标识。
步骤704为可选步骤。
SMF+PGW-C标记第一QoS流的方法可以参考AMF标记第一QoS流的方法。SMF+PGW-C可以在标记第一QoS流后删除第一承载和/或第一QoS流，也可以将第一承载和第一QoS流保留至同步后再删除。
若步骤704中SMF+PGW-C未删除第一承载和/或第一QoS流，则可以在步骤709或713或718中删除第一承载和/或第一QoS流。
需要说明的是，步骤701-704仅适用于SMF+PGW-C删除了第一承载和/或第一QoS流而未通知到UE的情况。
705.处于空闲态的UE从5G系统向4G系统切换时，若无N26接口，则UE向E-UTRAN发送附着请求，且步骤707-711省略；若有N26接口，则UE向E-UTRAN发送跟踪区域更新(tracking area update，TAU)请求，此时，步骤707-711不可省略。
可选的，附着请求或TAU请求中可以包含指示信息5，指示信息5可以指示UE上的EPS承载状态(EPS bearer status)和/或QoS流状态(Qos flow status)等，此时，指示信息5即前文所述的第一状态信息。
在另外一种情况中，若UE删除了第一QoS流而未通知到SMF+PGW-C，则上述指示信息5可以指示第一QoS流，而非UE本地的全部QoS流。可选地，此时UE也可以使用指示信息5指示UE上的EPS承载状态和/或QoS流状态。
可选的，在另一种实现方式中，UE也可以通过PCO将上述指示信息5发送至SMF+PGW-C。
706.E-UTRAN将UE的附着请求或TAU请求发送至AMF。可选的，该附着请求或TAU请求包含UE发送的指示信息5。
707.MME通过N26接口从AMF请求获取UE的上下文信息。可选地，该获取上下文请求可以携带指示信息5。
708.AMF向SMF+PGW-C请求获取UE的上下文信息。可选的，该获取上下文请求可以携带指示信息5。
709.SMF+PGW-C同步QoS流状态。该步骤为可选的步骤。
SMF+PGW-C可以根据指示信息5或者根据步骤704中标记的第一QoS流确定待同步的QoS流(即，第一QoS流)。并且，SMF+PGW-C可以按照下列三种方法中的一种同步QoS流状态。
(1)SMF+PGW-C可以向UE发送指示信息6，指示UE删除第一承载和/或第一QoS流。
(2)SMF+PGW-C发起承载修改流程，即，执行步骤718。其中，步骤716-717可以省略。
(3)SMF+PGW-C可以在步骤710、711或714中向UE发送步骤701中的PCO，或者，SMF+PGW-C可以在完成5G系统到4G系统的互通流程(步骤715之后以及步骤717之间，图中未示出)后，再向UE发送一个PCO。该PCO可以单独发送，也可以是包含在4G系统的其它流程消息中发送给UE。该PCO消息可以指示UE删除第一承载和/或第一QoS流，当UE向SMF+PGW-C返回PCO响应消息后，SMF+PGW-C可以发起承载修改流程或承载释放流程，在承载修改流程或承载释放流程中指示UE删除第一承载和/或第一QoS流。
若执行步骤709，则步骤713省略。若执行步骤713，则步骤709省略，步骤714中的会话建立响应包含指示信息6。
710.SMF+PGW-C向AMF返回UE的上下文信息。若步骤709被执行，则终端 上下文信息可以携带指示信息6。
711.AMF向MME发送UE的上下文信息。
可选地，若步骤709被执行，该上下文信息可以包含指示信息6，例如，指示信息6承载于EPS承载状态(EPS bearer status)信息中。指示信息6也可以单独发送给MME。
可选地，若步骤709未被执行，则该上下文信息可以包含AMF所标记的第一QoS流，例如，AMF所标记的第一QoS流承载于EPS承载状态(EPS bearer status)信息中。AMF所标记的第一QoS流也可以单独发送给MME。
步骤707-711在无N26接口的情况下可以省略。
712.MME通过SGW(图中未画出)向SMF+PGW-C发送建立会话请求。
若步骤707中的获取上下文请求不包含指示信息5，则步骤712中的建立会话请求可以包含UE发送的指示信息5。
713.同步骤709相关操作。
若执行本步骤，则步骤709可被省略。
若本步骤为步骤709中的方法(3)，则PCO承载于步骤714-715中的消息中。
714.SMF+PGW-C向MME发送会话建立响应消息。
若步骤709中的方法(1)被执行，则会话建立响应消息可以包含指示信息6。指示信息6可以是单独的指示信息，也可以是包含在PCO中的信息。在该情况下，步骤717-718省略。
若步骤709中的方法(3)被执行，则会话建立响应消息包含步骤701中的PCO，该PCO指示UE删除该第一承载和/或第一QoS流。
715.MME向终端发送附着接受消息或TAU接受消息。
若步骤709中的方法(1)被执行，则附着接受消息或TAU接受消息包含指示信息6。该指示信息6可以是单独的指示信息，也可以是包含在PCO中的信息。
若步骤709中的方法(3)被执行，则附着接受消息或TAU接受消息包含步骤701中的PCO，该PCO指示UE删除该第一承载和/或第一QoS流。
716.本步骤为可选的步骤。
若步骤709中的方法(2)被执行，则本步骤省略。
若步骤709中的方法(1)被执行，UE可以根据指示信息6删除第一承载和/或第一QoS流。或者，UE根据指示信息6发起承载修改流程，此时步骤716-717省略。
若步骤709中的方法(3)被执行，且UE可以直接删除本地的第一承载和/或第一QoS流，则步骤716可在步骤717之前或之后进行，步骤718可省略(SMF+PGW-C在步骤511或步骤504中已删除本地存储的第一承载和/或第一QoS流)，或者，SMF+PGW-C在步骤718中删除本地的第一承载和/或第一QoS流(SMF+PGW-C在步骤511和步骤504中未删除本地存储的第一承载和/或第一QoS流)。
717.UE向SMF+PGW-C发送PCO响应消息，用于通知SMF+PGW-C该UE已确认待删除的第一承载和/或第一QoS流，或，该PCO响应消息用于通知SMF+PGW-C该UE已删除了本地的第一承载和/或第一QoS流。
718.若步骤709中的方法(2)被执行，则SMF+PGW-C可以发起承载修改流程 或承载释放流程，该承载修改流程或承载释放流程用于触发UE删除第一承载和/或第一QoS流。其中，若SMF+PGW-C未在步骤704或步骤709或步骤713中删除第一承载和/或第一QoS流，可以在步骤718中删除第一承载和/或第一QoS流。具体流程可参考现有协议。
若UE已删除了本地的第一承载和/或第一QoS流，且SMF+PGW-C未在步骤704或步骤709或步骤713中删除第一承载和/或第一QoS流，则SMF+PGW-C可以在步骤718中删除本地的第一承载和/或第一QoS流。
若步骤709中的方法(2)被执行，步骤718可以在步骤709之后的任何时间执行，若步骤709不被执行，且步骤713被执行，则步骤718可以在步骤713之后的任何时间执行。
可选地，SMF+PGW-C还可以按照下列方法确定待同步的数据通道。若SMF+PGW-C在5G系统中发起删除QoS流的流程，则SMF+PGW-C标记其发起的删除QoS流的流程，当UE完成4G系统的注册流程后，SMF+PGW-C将触发承载修改流程，以同步UE和SMF+PGW-C的数据通道。
例如，在步骤701前或步骤701后，SMF+PGW-C记录其发起的承载删除QoS流的标识，若在4G网络中发生多次QoS流删除流程(每次QoS流删除流程可以删除一个或多个QoS流)，则SMF+PGW-C可标记一次或多次。若SMF+PGW-C仅标记一次，则可以仅标记第一次QoS流删除流程或最后一次QoS流删除流程。随后，SMF+PGW-C可以指示SMF+PGW-C将触发承载修改流程，以同步UE和SMF+PGW-C的数据通道。
类似地，若UE删除了QoS流，则UE记录已删除的QoS流，待通信系统切换完成后，UE发起承载修改流程与核心网网元进行数据通道同步处理。
上述实施例主要描述了SMF+PGW-C指示UE进行同步的方法，可选地，MME也可以指示UE进行同步。如图8所示。
该方法适用于终端设备从5G系统切换至4G系统的场景，并且，该方法可以适用于有N26接口的情况。
步骤801-804与步骤701-704相同，不再赘述。
805.处于空闲态的UE从5G系统向4G系统切换时，向E-UTRAN发送TAU请求。
可选的，TAU请求中包含指示信息5，指示信息5可以指示UE上的EPS承载状态(EPS bearer status)和/或QoS流状态(Qos flow status)等，此时，指示信息5即前文所述的第一状态信息。
在另外一种情况中，若UE删除了第一QoS流而未通知到SMF+PGW-C，则上述指示信息5可以指示第一QoS流，而非UE本地的全部QoS流。可选地，此时UE也可以使用指示信息5指示UE上的EPS承载状态和/或QoS流状态。
UE也可以通过PCO将上述指示信息5发送至SMF+PGW-C。
806.E-UTRAN将UE的TAU请求发送至MME。可选的，该TAU请求包含UE发送的指示信息5。
809.5G到4G移动性注册部分流程，具体过程可以参考通信协议(3GPP TS 23.502: "Procedures for the 5G System；Stage 2")。
810.MME向UE发送TAU接受消息，该消息包含指示信息7。其中，指示信息7可以直接指示UE删除第一承载和/或第一QoS流，或者，指示信息7也可以指示UE发起承载修改流程或承载释放流程。
811.UE接收到相应的指示信息后，删除第一承载和/或第一QoS流，或者，发起承载修改流程或承载释放流程，以便于MME和SMF+PGW-C同步承载。
可选地，若UE已删除了本地的第一承载和/或第一QoS流，或者，若UE确定删除本地的第一承载和/或第一QoS流，但是，UE未通知到SMF+PGW-C，则UE可以发起承载修改流程，在承载修改流程中通知SMF+PGW-C删除SMF+PGW-C存储的第一承载和/或第一QoS流。
图11示出了本申请提供的一种通信方法。该方法以终端设备从4G系统切换至5G系统的场景为例进行描述，此外，也适用于终端设备从5G系统切换至4G系统的场景。并且，该方法可以适用于有N26接口和无N26接口的情况。图11的方法可以适用于UE删除了第一承载和/或第一QoS流而未通知到网络侧的情况。
1101.UE删除了第一EPS承载，但是由于UE处于空闲态或无线信号丢失等原因，UE未成功通知网络侧删除第一EPS承载，即，网络侧的第一EPS承载的状态实际上待与UE同步。
1102.处于空闲态的UE从4G向5G切换时，向NG-RAN发送注册请求。由于UE删除了第一EPS承载但未成功通知网络侧删除第一EPS承载，该注册请求包括指示信息5。在一种可能的实现方式中，指示信息5可以指示上述第一EPS承载的状态。在另一种可能的实现方式中，指示信息5可以指示UE中各EPS承载的状态(即，前面提到的第一状态信息)和/或QoS流状态。
1103.NG-RAN将UE的注册请求发送至AMF，该注册请求包含UE发送的指示信息5。
1104.4G到5G移动性注册部分流程，具体过程可以参考通信协议(3GPP TS 23.502:"Procedures for the 5G System；Stage 2")。
1105.AMF向SMF+PGW-C发送会话建立请求，该会话建立请求携带UE发送的指示信息5。例如，指示信息5可以包含在会话建立请求消息中，或者，包含在会话建立响应消息中的PCO中，或者，也可以包含在其他消息中发送给UE。
1106.SMF+PGW-C可以根据指示信息5确定第一承载。
例如，当指示信息5指示UE中各EPS承载的状态时，SMF+PGW-C可以确定指示信息1指示的承载与SMF+PGW-C本地的承载相异的承载即为第一承载。
或者，当指示信息5指示第一EPS承载的状态时，SMF+PGW-C可以确定指示信息5指示的承载即为第一承载。
1107.SMF+PGW-C同步承载状态。
步骤1106和1107可参考图2中S210和S220的描述，此处不再赘述。
1108.SMF+PGW-C向AMF发送会话建立响应消息。
1109.AMF向NG-RAN发送注册接受消息。
1110.NG-RAN向UE发送注册接受消息。
图12示出了本申请提供的另一种通信方法。该方法以终端设备从4G系统切换至5G系统的场景为例进行描述，此外，也适用于终端设备从5G系统切换至4G系统的场景。并且，该方法可以适用于有N26接口和无N26接口的情况。图11的方法也适用于SMF+PGW-C删除了第一承载和/或第一QoS流而未通知到UE的情况。
1201.在4G网络中SMF+PGW-C向MME发送删除承载请求，用于请求删除第一承载。
1202.MME向SMF+PGW-C发送删除承载响应。
步骤1201和1202可参考图5中501和503的描述，此处不再赘述。
步骤1203.处于空闲态的UE从4G向5G切换时，向NG-RAN发送注册请求。也就是说，UE发起4G到5G的移动性注册流程。
1204.NG-RAN将UE的注册请求发送至AMF。
1205.AMF通过N26接口从MME请求获取UE的上下文。
1206.MME向AMF发送UE的上下文。
步骤1205和1206适用于MME和AMF之间支持N26接口的场景。当MME和AMF之间不支持N26接口，不执行步骤1205和1206。
1207.4G到5G移动性注册部分流程，具体过程可以参考通信协议(3GPP TS 23.502:"Procedures for the 5G System；Stage 2")。
1208.AMF向SMF+PGW-C发送会话建立请求。
1209.SMF+PGW-C向AMF发送会话建立响应。
在一种可能的实现方式中，由于SMF+PGW-C中存有EPS承载标识(EPS bearer ID，EBI)和分配和保留优先级(allocation and retention priority，ARP)之间的对应关系，会话建立响应中可包括上述EBI和ARP之间的对应关系。
在另一种可能的实现方式中，会话建立响应中包括EBI。
此处的EBI可以理解为用于标识在网络侧处于未被删除状态的EPS承载，或者说，可以理解为用于标识可以在互通时进行切换的EPS承载。
1210.AMF生成EPS承载状态(EPS bearer status)信息(即，前面提到的第二状态信息)。
例如，AMF可能与多个SMF+PGW-C通信，AMF可以根据从各个SMF+PGW-C收到的会话建立响应生成EPS承载状态信息。
例如，AMF可以在EPS承载状态信息中记录会话建立响应消息中携带的上述EBI和ARP之间的对应关系中包含的EBI相应的状态，比如，将该EBI标识的该承载的字符位记录为表示未删除的值(例如，记录为1)。或者，AMF可以根据会话建立响应消息中携带的上述EBI生成EPS承载状态信息。可选的，AMF还可以在EPS承载状态信息中将会话建立响应消息中没有携带的EBI所标识的其他承载的字符位记录为表示已删除的值(例如，记录为0)。会话建立响应消息中没有携带的EBI所标识的承载即为已被SMF+PGW-C删除的承载，例如，包括上述第一承载。
例如，上述AMF记录的EPS承载状态信息包括与一个PDN连接关联的各个EPS承载的信息，已被SMF+PGW-C删除的第一承载为与该PDN连接关联的各个EPS承载中的其中一个或多个承载。
或者，AMF可以不执行步骤步骤1210，仅从收到的会话建立响应中确定上述EBI和ARP之间的对应关系中包含的EBI，或从会话建立响应中确定EBI。
可选的，上述步骤1209和1210还可以由如下步骤1209’替换：
1209’,SMF+PGW-C生成EPS承载状态(EPS bearer status)信息(即，前面提到的第二状态信息)，向AMF发送携带EPS承载状态信息的会话建立响应。
SMF+PGW-C生成EPS承载状态信息的方式可参考AMF生成EPS承载状态信息的方式，此处不再赘述。
1211.AMF向RAN发送注册接受消息。
若AMF执行了上述步骤1210或SMF执行了上述1209’，则注册接受消息中携带EPS承载状态信息。
否则，该注册接受消息中包括AMF确定的EBI。可选的，该注册接受消息中还可以包括与该EBI对应的SMF+PGW-C的地址信息。
1212.RAN向UE发送注册接受消息。
若AMF执行了上述步骤1210，则注册接受消息中携带EPS承载状态信息。
否则，该注册接受消息中包括AMF确定的EBI。可选的，该注册接受消息中还可以包括与该EBI对应的SMF+PGW-C的地址信息。
1213.UE根据收到的信息进行同步。
若注册接受消息中包含EPS承载状态信息，UE将从AMF收到的EPS承载状态信息与本地存储的EPS承载状态信息进行比较，若发现有不同信息不同的EPS承载，则UE释放该EPS承载，并删除与该EPS承载对应的QoS流的信息(例如，QFI规则和QoS参数)。
若注册接受消息中包含EBI，UE检查本地存储的EPS承载状态信息中是否包括收到的EBI，若包括，则UE释放该EPS承载，并删除与该EPS承载对应的QoS流的信息(例如，QFI规则和QoS参数)。
上文详细介绍了本申请提供的通信方法的示例。可以理解的是，通信装置为了实现上述功能，其包含了执行各个功能相应的硬件结构和/或软件模块。本领域技术人员应该很容易意识到，结合本文中所公开的实施例描述的各示例的单元及算法步骤，本申请能够以硬件或硬件和计算机软件的结合形式来实现。某个功能究竟以硬件还是计算机软件驱动硬件的方式来执行，取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本申请的范围。
本申请可以根据上述方法示例对通信装置进行功能单元的划分，例如，可以将各个功能划分为各个功能单元，也可以将两个或两个以上的功能集成在一个处理单元中。上述集成的单元既可以采用硬件的形式实现，也可以采用软件功能单元的形式实现。需要说明的是，本申请中对单元的划分是示意性的，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式。
图9示出了本申请提供的一种通信装置的结构示意图。通信装置900可用于实现上述方法实施例中描述的方法。该通信装置900可以是芯片、网络设备或终端设备。
通信装置900包括一个或多个处理器901，该一个或多个处理器901可支持通信 装置900实现图2至图8或图11、图12中网络设备(会话管理网元或移动性管理网元)或者终端设备的方法。处理器901可以是通用处理器或者专用处理器。例如，处理器901可以是中央处理器(central processing unit，CPU)或基带处理器。基带处理器可以用于处理通信数据，CPU可以用于对通信装置(例如，网络设备、终端设备或芯片)进行控制，执行软件程序，处理软件程序的数据。通信装置900还可以包括收发单元905，用以实现信号的输入(接收)和输出(发送)。
例如，通信装置900可以是芯片，收发单元905可以是该芯片的输入和/或输出电路，或者，收发单元905可以是该芯片的通信接口，该芯片可以作为终端设备或网络设备或其它无线通信设备的组成部分。
通信装置900中可以包括一个或多个存储器902，其上存有程序904，程序904可被处理器901运行，生成指令903，使得处理器901根据指令903执行上述方法实施例中描述的方法。可选地，存储器902中还可以存储有数据。可选地，处理器901还可以读取存储器902中存储的数据，该数据可以与程序904存储在相同的存储地址，该数据也可以与程序904存储在不同的存储地址。
处理器901和存储器902可以单独设置，也可以集成在一起，例如，集成在单板或者系统级芯片(system on chip，SOC)上。
通信装置900还可以包括收发单元905以及天线906。收发单元905可以称为收发机、收发电路或者收发器，用于通过天线906实现通信装置的收发功能。
在一种可能的设计中，处理器901用于执行：
确定第一系统中的第一数据通道，所述第一数据通道为待与终端设备同步的数据通道；
在所述终端设备从所述第一系统切换至第二系统的流程中同步以下中的至少一项：所述第一数据通道，或，所述第二系统中与所述第一数据通道对应的第二数据通道。
在另一种可能的设计中，处理器901用于执行：
确定第一系统中的第一数据通道，所述第一数据通道为待与会话管理网元同步的数据通道；
在从所述第一系统切换至第二系统后同步以下中的至少一项：所述第一数据通道，或，所述第二系统中与所述第一数据通道对应的第二数据通道。
上述可能的设计的实现方式可以参见上述方法实施例中的相关描述。
应理解，上述方法实施例的各步骤可以通过处理器901中的硬件形式的逻辑电路或者软件形式的指令完成。处理器901可以是CPU、数字信号处理器(digital signal processor，DSP)、专用集成电路(application specific integrated circuit，ASIC)、现场可编程门阵列(field programmable gate array，FPGA)或者其它可编程逻辑器件，例如，分立门、晶体管逻辑器件或分立硬件组件。
本申请还提供了一种计算机程序产品，该计算机程序产品被处理器901执行时实现本申请中任一方法实施例所述的通信方法。
该计算机程序产品可以存储在存储器902中，例如是程序904，程序904经过预处理、编译、汇编和链接等处理过程最终被转换为能够被处理器901执行的可执行目标文件。
本申请还提供了一种计算机可读存储介质，其上存储有计算机程序，该计算机程序被计算机执行时实现本申请中任一方法实施例所述的通信方法。该计算机程序可以是高级语言程序，也可以是可执行目标程序。
该计算机可读存储介质例如是存储器902。存储器902可以是易失性存储器或非易失性存储器，或者，存储器902可以同时包括易失性存储器和非易失性存储器。其中，非易失性存储器可以是只读存储器(read-only memory，ROM)、可编程只读存储器(programmable ROM，PROM)、可擦除可编程只读存储器(erasable PROM，EPROM)、电可擦除可编程只读存储器(electrically EPROM，EEPROM)或闪存。易失性存储器可以是随机存取存储器(random access memory，RAM)，其用作外部高速缓存。通过示例性但不是限制性说明，许多形式的RAM可用，例如静态随机存取存储器(static RAM，SRAM)、动态随机存取存储器(dynamic RAM，DRAM)、同步动态随机存取存储器(synchronous DRAM，SDRAM)、双倍数据速率同步动态随机存取存储器(double data rate SDRAM，DDR SDRAM)、增强型同步动态随机存取存储器(enhanced SDRAM，ESDRAM)、同步连接动态随机存取存储器(synchlink DRAM，SLDRAM)和直接内存总线随机存取存储器(direct rambus RAM，DR RAM)。
在通信装置900为终端设备的情况下，图10示出了本申请提供的一种终端设备的结构示意图。该终端设备1000可适用于图1所示的系统中，实现上述图2至图8或图11、图12方法实施例中终端设备的功能。为了便于说明，图10仅示出了终端设备的主要部件。
如图10所示，终端设备1000包括处理器、存储器、控制电路、天线以及输入输出装置。处理器主要用于对通信协议以及通信数据进行处理，以及用于对整个终端设备进行控制。例如，处理器通过天线和控制电路接收功耗节省信号。存储器主要用于存储程序和数据，例如存储通信协议和待发送数据。控制电路主要用于基带信号与射频信号的转换以及对射频信号的处理。控制电路和天线一起也可以叫做收发器，主要用于收发电磁波形式的射频信号。输入输出装置例如是触摸屏或键盘，主要用于接收用户输入的数据以及对用户输出数据。
当终端设备开机后，处理器可以读取存储器中的程序，解释并执行该程序所包含的指令，处理程序中的数据。当需要通过天线发送信息时，处理器对待发送的信息进行基带处理后，输出基带信号至射频电路，射频电路将基带信号进行射频处理后得到射频信号，并将射频信号通过天线以电磁波的形式向外发送。当承载信息的电磁波(即，射频信号)到达终端设备时，射频电路通过天线接收到射频信号，将射频信号转换为基带信号，并将基带信号输出至处理器，处理器将基带信号转换为信息并对该信息进行处理。
本领域技术人员可以理解，为了便于说明，图10仅示出了一个存储器和一个处理器。在实际的终端设备中，可以存在多个处理器和多个存储器。存储器也可以称为存储介质或者存储设备等，本申请对此不做限定。
作为一种可选的实现方式，图10中的处理器可以集成基带处理器和CPU的功能，本领域技术人员可以理解，基带处理器和CPU也可以是各自独立的处理器，通过总线等技术互联。本领域技术人员可以理解，终端设备可以包括多个基带处理器以适应不 同的网络制式，终端设备可以包括多个CPU以增强其处理能力，终端设备的各个部件可以通过各种总线连接。基带处理器也可以被称为基带处理电路或者基带处理芯片。CPU也可以被称为中央处理电路或者中央处理芯片。对通信协议以及通信数据进行处理的功能可以内置在处理器中，也可以以程序的形式存储在存储器中，由处理器执行存储器中的程序以实现基带处理功能。
在本申请中，可以将具有收发功能的天线和控制电路视为终端设备1000的收发器1001，用于支持终端设备实现方法实施例中的接收功能，或者，用于支持终端设备实现方法实施例中的发送功能。将具有处理功能的处理器视为终端设备1000的处理器1002。如图10所示，终端设备1000包括收发器1001和处理器1002。收发器也可以称为收发机、收发装置等。可选地，可以将收发器1001中用于实现接收功能的器件视为接收器，将收发单元1001中用于实现发送功能的器件视为发送器。即，收发器1001包括接收器和发送器，接收器也可以称为接收机、输入口、接收电路等，发送器可以称为发射机、输出口、发射电路等。
处理器1002可用于执行存储器存储的程序，以控制收发单元1001接收信号和/或发送信号，完成上述方法实施例中终端设备的功能。作为一种实现方式，收发单元1001的功能可以考虑通过收发电路或者收发专用芯片实现。
本领域的技术人员可以清楚地了解到，为了描述的方便和简洁，上述描述的系统、装置和单元的具体工作过程，可以参考前述方法实施例中的对应过程，在此不再赘述。
在本申请所提供的几个实施例中，所揭露的系统、装置和方法，可以通过其它的方式实现。例如，以上所描述的方法实施例的一些特征可以忽略，或不执行。以上所描述的装置实施例仅仅是示意性的，单元的划分，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，多个单元或组件可以结合或者可以集成到另一个系统。另外，各单元之间的耦合或各个组件之间的耦合可以是直接耦合，也可以是间接耦合，上述耦合包括电的、机械的或其它形式的连接。
应理解，在本申请的各种实施例中，各过程的序号的大小并不意味着执行顺序的先后，各过程的执行顺序应以其功能和内在逻辑确定，而不应对本申请的实施例的实施过程构成任何限定。
另外，本文中术语“系统”和“网络”在本文中常被可互换使用。本文中的术语“和/或”，仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。另外，本文中字符“/”，一般表示前后关联对象是一种“或”的关系。
总之，以上所述仅为本申请技术方案的较佳实施例而已，并非用于限定本申请的保护范围。凡在本申请的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本申请的保护范围之内。
以上所述，仅为本发明的具体实施方式，但本发明的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本发明揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本发明的保护范围之内。因此，本发明的保护范围应以所述权利要求的保护范围为准。

Claims (50)

  1. 一种通信方法，其特征在于，包括：
    会话管理网元确定第一系统中的第一数据通道，所述第一数据通道为待与终端设备同步的数据通道；
    所述会话管理网元在所述终端设备从所述第一系统切换至第二系统的流程中同步以下中的至少一项：所述第一数据通道，或，所述第二系统中与所述第一数据通道对应的第二数据通道。
  2. 根据权利要求1所述的方法，其特征在于，所述会话管理网元确定第一系统中的第一数据通道，包括：
    所述会话管理网元接收第一状态信息，所述第一状态信息用于指示所述终端设备中的数据通道的状态；
    所述会话管理网元根据所述第一状态信息确定所述第一数据通道。
  3. 根据权利要求1所述的方法，其特征在于，所述会话管理网元确定第一系统中的第一数据通道，包括：
    所述会话管理网元向所述终端设备发送协议配置选项PCO；
    当所述会话管理网元收到不携带PCO的响应消息时，所述会话管理网元确定所述第一数据通道。
  4. 根据权利要求3所述的方法，其特征在于，所述PCO包括所述第一数据通道的信息或所述第二数据通道的信息中的至少一项。
  5. 根据权利要求1所述的方法，其特征在于，所述会话管理网元确定第一系统中的第一数据通道，包括：
    所述会话管理网元向所述第一系统中的移动性管理网元发送第一消息，第一消息用于指示删除一个或多个数据通道；
    所述会话管理网元从所述第一系统中的移动性管理网元接收第二消息，第二消息用于指示所述第一消息未通知到所述终端设备；
    所述会话管理网元根据所述第二消息将所述一个或多个数据通道确定为所述第一数据通道。
  6. 根据权利要求1至5中任一项所述的方法，其特征在于，所述会话管理网元在所述终端设备从所述第一系统切换至第二系统的流程中同步以下中的至少一项：所述第一数据通道，或，所述第二系统中与所述第一数据通道对应的第二数据通道；包括：
    所述会话管理网元触发会话修改流程，所述会话修改流程用于同步以下中的至少一项：所述第一数据通道，或，所述第二系统中与所述第一数据通道对应的第二数据通道；或者，
    所述会话管理网元在协议数据单元PDU会话激活过程中触发以下中的至少一项的同步：所述第一数据通道，或，所述第二系统中与所述第一数据通道对应的第二数据通道。
  7. 根据权利要求1至6中任一项所述的方法，其特征在于，所述会话管理网元在所述终端设备从所述第一系统切换至第二系统的流程中同步以下中的至少一项：所述第一数据通道，或，所述第二系统中与所述第一数据通道对应的第二数据通道；包括：
    所述会话管理网元删除所述第一数据通道的信息或所述第二数据通道的信息中的至少一项；
    其中，当所述第一系统为4G系统，所述第二系统为5G系统，所述第一数据通道的信息包括演进的分组系统EPS承载的信息，所述第二数据通道的信息包括与所述EPS承载关联的QoS流的信息；或者
    当所述第一系统为5G系统，所述第二系统为4G系统，所述第一数据通道的信息包括QoS流的信息，所述第二数据通道的信息包括与所述QoS流关联的EPS承载的信息。
  8. 根据权利要求1至7中任一项所述的方法，其特征在于，所述第一数据通道为所述终端设备已经删除但是没有通知网络侧的数据通道。
  9. 一种通信方法，其特征在于，包括：
    第二系统中的移动性管理网元确定第一系统中的第一数据通道，所述第一数据通道为待与终端设备同步的数据通道；
    所述第二系统中的移动性管理管理网元在所述终端设备从所述第一系统切换至所述第二系统的流程中同步以下中的至少一项：所述第一数据通道，或，所述第二系统中与所述第一数据通道对应的第二数据通道。
  10. 根据权利要求9所述的方法，其特征在于，
    所述第二系统中的移动性管理网元确定所述第一系统中的第一数据通道，包括：
    所述第二系统中的移动性管理网元从所述终端设备接收第一状态信息，所述第一状态信息用于指示所述终端设备的数据通道的状态；
    所述第二系统中的移动性管理网元从所述第一系统中的移动性管理网元接收第二状态信息，所述第二状态信息用于指示所述终端设备的数据通道的状态；
    所述第二系统中的移动性管理网元根据所述第一状态信息和所述第二状态信息确定所述第一数据通道。
  11. 根据权利要求9或10所述的方法，其特征在于，所述方法还包括：
    所述第二系统中的移动性管理网元向会话管理网元发送所述第一状态信息，所述第一状态信息用于所述第一数据通道的确定。
  12. 一种通信方法，其特征在于，包括：
    终端设备确定第一系统中的第一数据通道，所述第一数据通道为待与会话管理网元同步的数据通道；
    所述终端设备在从所述第一系统切换至第二系统的流程中同步以下中的至少一项：所述第一数据通道，或，所述第二系统中与所述第一数据通道对应的第二数据通道。
  13. 根据权利要求12所述的方法，其特征在于，所述终端设备确定第一系统中的第一数据通道，包括：
    所述终端设备向所述会话管理网元发送通知消息，所述通知消息用于通知所述会话管理网元所述终端设备删除了一个或多个数据通道；
    所述终端设备根据未收到所述通知消息的响应消息将所述一个或多个数据通道确定为所述第一数据通道。
  14. 根据权利要求12所述的方法，其特征在于，所述方法还包括：
    所述终端设备向所述会话管理网元发送第一状态信息，所述第一状态信息指示所述终端设备中的数据通道的状态，所述第一状态信息用于所述第一数据通道的确定。
  15. 根据权利要求12所述的方法，其特征在于，所述终端设备确定第一系统中的第一数据通道，包括：
    所述终端设备接收第二状态信息，所述第二状态信息用于指示所述会话管理网元中的数据通道的状态；
    所述终端设备根据所述第二状态信息确定所述第一数据通道。
  16. 根据权利要求12至15中任一项所述的方法，其特征在于，所述终端设备在从所述第一系统切换至第二系统的流程中同步以下中的至少一项：所述第一数据通道，或，所述第二系统中与所述第一数据通道对应的第二数据通道；包括：
    所述终端设备删除所述第一数据通道的信息或所述第二数据通道的信息中的至少一项；
    其中，当所述第一系统为4G系统，所述第二系统为5G系统，所述第一数据通道的信息包括演进的分组系统EPS承载的信息，所述第二数据通道的信息包括与所述EPS承载关联的QoS流的信息；或者
    当所述第一系统为5G系统，所述第二系统为4G系统，所述第一数据通道的信息包括QoS流的信息，所述第二数据通道的信息包括与所述QoS流关联的EPS承载的信息。
  17. 根据权利要求12至16中任一项所述的方法，其特征在于，所述方法还包括：
    所述终端设备从所述会话管理网元接收PCO；
    所述终端设备向所述会话管理网元发送所述PCO的响应消息，所述PCO的响应消息不包括任何参数，或者，所述PCO包括所述第一数据通道的信息或所述第二数据通道的信息中的至少一项。
  18. 根据权利要求17所述的方法，其特征在于，所述PCO的响应消息用于指示所述终端设备已删除待删除的数据通道，或者，所述PCO的响应消息用于指示所述终端设备已确定删除待删除的数据通道，或者，所述PCO的响应消息用于指示所述终端设备已接收到所述PCO消息。
  19. 一种通信装置，其特征在于，包括处理单元，所述处理单元用于：
    确定第一系统中的第一数据通道，所述第一数据通道为待与终端设备同步的数据通道；
    在所述终端设备从所述第一系统切换至第二系统的流程中同步以下中的至少一项：所述第一数据通道，或，所述第二系统中与所述第一数据通道对应的第二数据通道。
  20. 根据权利要求19所述的装置，其特征在于，所述处理单元具体用于：
    控制接收单元接收第一状态信息，所述第一状态信息用于指示所述终端设备中的数据通道的状态；
    根据所述第一状态信息确定所述第一数据通道。
  21. 根据权利要求19所述的装置，其特征在于，所述处理单元具体用于：
    控制发送单元向所述终端设备发送协议配置选项PCO；
    当收到不携带PCO的响应消息时，确定所述第一数据通道。
  22. 根据权利要求21所述的装置，其特征在于，所述PCO包括所述第一数据通道的信息或所述第二数据通道的信息中的至少一项。
  23. 根据权利要求19所述的装置，其特征在于，所述处理单元具体用于：
    控制发送单元向所述第一系统中的移动性管理网元发送第一消息，第一消息用于指示删除一个或多个数据通道；
    控制接收单元从所述第一系统中的移动性管理网元接收第二消息，第二消息用于指示所述第一消息未通知到所述终端设备；
    根据所述第二消息将所述一个或多个数据通道确定为所述第一数据通道。
  24. 根据权利要求19至23中任一项所述的装置，其特征在于，所述处理单元具体用于：
    触发会话修改流程，所述会话修改流程用于同步以下中的至少一项：所述第一数据通道，或，所述第二系统中与所述第一数据通道对应的第二数据通道；或者，
    在协议数据单元PDU会话激活过程中触发以下中的至少一项的同步：所述第一数据通道，或，所述第二系统中与所述第一数据通道对应的第二数据通道。
  25. 根据权利要求19至24中任一项所述的装置，其特征在于，所述处理单元具体用于：
    删除所述第一数据通道的信息或所述第二数据通道的信息中的至少一项；
    其中，当所述第一系统为4G系统，所述第二系统为5G系统，所述第一数据通道的信息包括演进的分组系统EPS承载的信息，所述第二数据通道的信息包括与所述EPS承载关联的QoS流的信息；或者
    当所述第一系统为5G系统，所述第二系统为4G系统，所述第一数据通道的信息包括QoS流的信息，所述第二数据通道的信息包括与所述QoS流关联的EPS承载的信息。
  26. 根据权利要求19至25中任一项所述的装置，其特征在于，所述第一数据通道为所述终端设备已经删除但是没有通知网络侧的数据通道。
  27. 一种通信装置，其特征在于，被配置于第二系统中，所述通信装置包括处理单元，所述处理单元用于：
    确定第一系统中的第一数据通道，所述第一数据通道为待与终端设备同步的数据通道；
    在所述终端设备从所述第一系统切换至所述第二系统的流程中同步以下中的至少一项：所述第一数据通道，或，所述第二系统中与所述第一数据通道对应的第二数据通道。
  28. 根据权利要求27所述的装置，其特征在于，
    所述处理单元具体用于：
    控制第一接收单元从所述终端设备接收第一状态信息，所述第一状态信息用于指示所述终端设备的数据通道的状态；
    控制第二接收单元从所述第一系统中的移动性管理网元接收第二状态信息，所述第二状态信息用于指示所述终端设备的数据通道的状态；
    根据所述第一状态信息和所述第二状态信息确定所述第一数据通道。
  29. 根据权利要求27或28所述的装置，其特征在于，所述处理单元还用于：
    控制发送单元向会话管理网元发送所述第一状态信息，所述第一状态信息用于所述第一数据通道的确定。
  30. 一种通信装置，其特征在于，包括处理单元，所述处理单元用于：
    确定第一系统中的第一数据通道，所述第一数据通道为待与会话管理网元同步的数据通道；
    在从所述第一系统切换至第二系统的流程中同步以下中的至少一项：所述第一数据通道，或，所述第二系统中与所述第一数据通道对应的第二数据通道。
  31. 根据权利要求30所述的装置，其特征在于，所述处理单元具体用于：
    控制发送单元向所述会话管理网元发送通知消息，所述通知消息用于通知所述会话管理网元所述终端设备删除了一个或多个数据通道；
    根据未收到所述通知消息的响应消息将所述一个或多个数据通道确定为所述第一数据通道。
  32. 根据权利要求30所述的装置，其特征在于，所述处理单元还用于：
    控制发送单元向所述会话管理网元发送第一状态信息，所述第一状态信息指示所述终端设备中的数据通道的状态，所述第一状态信息用于所述第一数据通道的确定。
  33. 根据权利要求30所述的装置，其特征在于，所述处理单元具体用于：
    控制接收单元接收第二状态信息，所述第二状态信息用于指示所述会话管理网元中的数据通道的状态；
    根据所述第二状态信息确定所述第一数据通道。
  34. 根据权利要求30至33中任一项所述的装置，其特征在于，所述处理单元具体用于：
    删除所述第一数据通道的信息或所述第二数据通道的信息中的至少一项；
    其中，当所述第一系统为4G系统，所述第二系统为5G系统，所述第一数据通道的信息包括演进的分组系统EPS承载的信息，所述第二数据通道的信息包括与所述EPS承载关联的QoS流的信息；或者
    当所述第一系统为5G系统，所述第二系统为4G系统，所述第一数据通道的信息包括QoS流的信息，所述第二数据通道的信息包括与所述QoS流关联的EPS承载的信息。
  35. 根据权利要求30至34中任一项所述的装置，其特征在于，所述处理单元还用于：
    控制接收单元从所述会话管理网元接收PCO；
    控制发送单元向所述会话管理网元发送所述PCO的响应消息，所述PCO的响应消息不包括任何参数，或者，所述PCO包括所述第一数据通道的信息或所述第二数据通道的信息中的至少一项。
  36. 根据权利要求35所述的装置，其特征在于，所述PCO的响应消息用于指示所述终端设备已删除待删除的数据通道，或者，所述PCO的响应消息用于指示所述终端设备已确定删除待删除的数据通道，或者，所述PCO的响应消息用于指示所述终端设备已接收到所述PCO消息。
  37. 一种通信方法，其特征在于，包括：
    终端设备确定所述终端设备已经在第一系统中删除但没有通知网络侧的第一数据通道；
    所述终端设备向会话管理网元发送第一状态信息，所述第一状态信息指示所述终端设备中的数据通道的状态，该第一状态信息用于所述第一数据通道的确定。
  38. 根据权利要求37所述的方法，所述终端设备向会话管理网元发送第一状态信息，包括：
    所述终端设备向移动性管理网元发送第一消息，所述第一消息中包括所述第一状态信息，其中，所述第一消息为附着请求消息、注册请求消息、或会话建立请求消息。
  39. 一种通信装置，其特征在于，包括：
    处理单元，用于确定终端设备已经在第一系统中删除但没有通知网络侧的第一数据通道；
    发送单元，用于向会话管理网元发送第一状态信息，所述第一状态信息指示所述终端设备中的数据通道的状态，该第一状态信息用于所述第一数据通道的确定。
  40. 根据权利要求39所述的装置，所述发送单元用于向接入和移动性管理网元发送第一消息，所述第一消息中包括所述第一状态信息，其中，所述第一消息为附着请求消息、注册请求消息、或会话建立请求消息。
  41. 一种通信方法，其特征在于，包括：
    会话管理网元删除第一系统中的第一数据通道，所述第一数据通道为待与终端设备同步的数据通道；
    所述会话管理网元向第二系统中的移动性管理网元发送数据通道的信息，其中，所述数据通道的信息包括数据通道的标识信息，或者，数据通道的标识信息与分配和保留优先级之间的对应关系。
  42. 一种通信装置，其特征在于，包括：
    处理单元，用于删除第一系统中的第一数据通道，所述第一数据通道为待与终端设备同步的数据通道；
    发送单元，用于向第二系统中的移动性管理网元发送数据通道的信息，其中，所述数据通道的信息包括数据通道的标识信息，或者，数据通道的标识信息与分配和保留优先级之间的对应关系。
  43. 一种通信方法，其特征在于，包括：
    第二系统中的移动性管理网元从会话管理网元接收数据通道的信息，其中，所述数据通道的信息包括数据通道的标识信息，或者，所述标识信息与分配和保留优先级之间的对应关系，
    所述移动性管理网元根据所述数据通道的信息确定状态信息；
    所述移动性管理网元向所述终端设备发送所述状态信息，所述状态信息用于所述终端设备侧对于以下中至少一项的同步：第一数据通道，或，所述第二系统中与第一数据通道对应的第二数据通道；
    其中，所述第一数据通道为待与所述终端设备同步的数据通道。
  44. 一种通信装置，其特征在于，位于第二系统中，所述通信装置包括：
    接收单元，用于从会话管理网元接收数据通道的信息，其中，所述数据通道的信息包括数据通道的标识信息，或者，数据通道的标识信息与分配和保留优先级之间的对应关系；
    处理单元，用于根据所述数据通道的信息确定状态信息；
    发送单元，用于向所述终端设备发送所述状态信息，所述状态信息用于所述终端设备侧对于以下中至少一项的同步：第一数据通道，或，所述第二系统中与第一数据通道对应的第二数据通道；
    其中，所述第一数据通道为待与终端设备同步的数据通道。
  45. 一种通信系统，其特征在于，包括：
    会话管理网元，用于删除第一系统中的第一数据通道，所述第一数据通道为待与终端设备同步的数据通道；向第二系统中的移动性管理网元发送数据通道的信息，其中，所述数据通道的信息包括数据通道的标识信息，或者，数据通道的标识信息与分配和保留优先级之间的对应关系；
    所述移动性管理网元，用于从所述会话管理网元接收所述数据通道的信息；根据所述数据通道的信息确定状态信息；向所述终端设备发送所述状态信息，所述状态信息用于所述终端设备侧对于以下中至少一项的同步：所述第一数据通道，或，所述第二系统中与第一数据通道对应的第二数据通道。
  46. 一种通信方法，其特征在于，包括：
    终端设备从第二系统中的移动性管理网元接收状态信息；
    所述终端设备根据所述状态信息确定第一数据通道，所述第一数据通道为待与终端设备同步的数据通道；
    所述终端设备同步以下中的至少一项：所述第一数据通道，或，所述第二系统中与所述第一数据通道对应的第二数据通道。
  47. 根据权利要求46所述的方法，其特征在于，所述终端设备同步以下中的至少一项：所述第一数据通道，或，所述第二系统中与所述第一数据通道对应的第二数据通道，包括：
    所述终端设备删除所述第一数据通道的信息或所述第二数据通道的信息中的至少一项；
    其中，当所述第一系统为4G系统，所述第二系统为5G系统，所述第一数据通道的信息包括演进的分组系统EPS承载的信息，所述第二数据通道的信息包括与所述EPS承载关联的QoS流的信息；或者
    当所述第一系统为5G系统，所述第二系统为4G系统，所述第一数据通道的信息包括QoS流的信息，所述第二数据通道的信息包括与所述QoS流关联的EPS承载的信息。
  48. 一种通信装置，其特征在于，包括：
    接收单元，用于从第二系统中的移动性管理网元接收状态信息；
    处理单元，用于根据所述状态信息确定第一数据通道，所述第一数据通道为待与终端设备同步的数据通道；同步以下中的至少一项：所述第一数据通道，或，所述第二系统中与所述第一数据通道对应的第二数据通道。
  49. 根据权利要求48所述的装置，其特征在于，所述处理单元用于删除所述第一数据通道的信息或所述第二数据通道的信息中的至少一项；
    其中，当所述第一系统为4G系统，所述第二系统为5G系统，所述第一数据通道的信息包括演进的分组系统EPS承载的信息，所述第二数据通道的信息包括与所述EPS承载关联的QoS流的信息；或者
    当所述第一系统为5G系统，所述第二系统为4G系统，所述第一数据通道的信息包括QoS流的信息，所述第二数据通道的信息包括与所述QoS流关联的EPS承载的信息。
  50. 一种计算机可读存储介质，其特征在于，所述计算机可读存储介质中存储了计算机程序，当所述计算机程序被处理器执行时，使得处理器执行权利要求1至7中任一项所述的方法，或者，使得处理器执行权利要求8至10中任一项所述的方法，或者，使得处理器执行权利要求11至17中任一项所述的方法，或者，使得处理器执行权利要求37、38、41、43或46中任一项所述的方法。
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