WO2022068424A1 - 通信方法及装置 - Google Patents

通信方法及装置 Download PDF

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Publication number
WO2022068424A1
WO2022068424A1 PCT/CN2021/112603 CN2021112603W WO2022068424A1 WO 2022068424 A1 WO2022068424 A1 WO 2022068424A1 CN 2021112603 W CN2021112603 W CN 2021112603W WO 2022068424 A1 WO2022068424 A1 WO 2022068424A1
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WO
WIPO (PCT)
Prior art keywords
pdu session
network element
user plane
access network
data packet
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PCT/CN2021/112603
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English (en)
French (fr)
Inventor
余芳
李岩
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华为技术有限公司
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Publication date
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Publication of WO2022068424A1 publication Critical patent/WO2022068424A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/04—Arrangements for maintaining operational condition
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W76/00—Connection management
    • H04W76/10—Connection setup

Definitions

  • the present application relates to the field of communication technologies, and in particular, to a communication method and device.
  • the reliability requirements for many industrial applications are basically above 99.9999%, and these applications with high reliability requirements basically also have high requirements for time delay.
  • the current communication architecture often cannot meet the reliability requirements in some communication scenarios. For example, in the communication scenario of the business related to the factory (to business, to B), the reliability requirement of the mobile control (motion control, MC) business for the terminal to other equipment is 999.999%, for example, the communication service terminal is allowed in one year. The total fault duration does not exceed 30 seconds.
  • the reliability of network equipment eg, access network equipment
  • the reliability of the entire communication link is far from satisfying the MC service.
  • a communication architecture may refer to FIG. 1, which may include a terminal, a first access network device, a second access network device, a first user plane function (UPF), and a second UPF.
  • the first access network device and the second access network device have similar (or the same) cell coverage capabilities.
  • the terminal establishes a communication connection with the core network through the first access network device.
  • the terminal may perform data or signaling interaction with the first UPF through the first access network device.
  • the service communication between the terminal and the data network (DN) of the back end of the first UPF is realized.
  • the second access network device can replace the first access network device to communicate with the terminal and the second UPF, so as to ensure uninterrupted service communication and improve the reliability of the communication link. Purpose.
  • the second access network device needs to know which data packet the first access network device has processed, so that the second access network device can replace the first access network device when the first access network device fails.
  • An access network device but currently there is no solution for how the second access network device knows which data packet the first access network device has processed, which may cause service interruption and fail to improve the reliability of the communication link.
  • Embodiments of the present application provide a communication method and apparatus, which are used to solve the problem of data packet processing synchronization between two access network devices in a dual UPF scenario, so as to ensure uninterrupted service communication and achieve the purpose of improving communication link reliability.
  • a communication method comprising: a session management network element sending, to a first user plane network element, an application layer sequence number and a GTP for instructing the first user plane network element to perform downlink data packets through a first mapping rule -
  • the first indication information for mapping the sequence numbers of the U layer
  • the second indication information of the mapping of the number wherein, the terminal establishes the first PDU session and the second PDU session to communicate with the data network, and the first user plane network element and the second user plane network element are the first PDU session and the second
  • the anchor point of the PDU session the access network devices accessed by the terminal include a first access network device and a second access network device, and the first access network device and the second access network device have the same cell configuration; wherein, When the application layer sequence number of the first downlink data packet received by the first user
  • the first user plane network element and the second user plane network element can use the same mapping rule to map the application layer sequence number of the downlink data packet and the GTP-U layer sequence number, so that in the first If the application layer sequence number of the first downlink data packet received by the user plane network element is the same as the application layer sequence number of the second downlink data packet received by the second user plane network element, the first user plane network element sends the The GTP-U layer sequence number of the first downlink data packet sent by the first access network device is the same as the GTP-U layer sequence number of the second downlink data packet sent by the second user plane network element to the second access network device , realize the synchronization of the data packet processing of the two access network devices (that is, realize the synchronization of the user plane packets of the two access network devices), so as to ensure that the service communication is not interrupted and achieve the purpose of improving the reliability of the communication link. .
  • the first indication information and the second indication information are further used to indicate the first mapping rule.
  • This possible implementation manner can reduce signaling overhead compared to using other indication information to indicate the first mapping rule.
  • the method further includes: the session management network element sends, to the terminal, third indication information for instructing the terminal to only send uplink data packets on the first PDU session.
  • the session management network element sends, to the terminal, third indication information for instructing the terminal to only send uplink data packets on the first PDU session.
  • the method further includes: the session management network element instructs the first access network device to process the first PDU session.
  • the method further includes: the session management network element receives the tunnel information of the first user plane network element from the first user plane network element, and sends the first user plane network element to the second user plane network element
  • the tunnel information of the first user plane network element is used for the second user plane network element to forward the uplink data packets of the first PDU session to the first user plane network element according to the tunnel information of the first user plane network element, wherein the tunnel of the first user plane network element
  • the information includes the tunnel endpoint identifier and IP address of the first user plane network element.
  • the method further includes: the session management network element receives from the first access network device an instruction to perform downlink The fourth indication information of the mapping between the application layer sequence number of the data packet and the GTP-U layer sequence number.
  • the session management network element sends the first indication information to the first user plane network element, including: the session management network element receives from the terminal a first PDU session establishment request for requesting establishment of the first PDU session ; In the case that the first PDU session establishment request includes the identifier of the second PDU session, the session management network element sends the first indication information to the first user plane network element.
  • This possible implementation provides an implementation for sending the first indication information.
  • the session management network element sends the second indication information to the second user plane network element, including: the session management network element receives from the terminal a second PDU session establishment request for requesting establishment of the second PDU session ; In the case that the identifier of the first PDU session is included in the second PDU session establishment request, the session management network element sends the second indication information to the second user plane network element.
  • This possible implementation provides an implementation for sending the second indication information.
  • a communication method including: a second user plane network element receiving second indication information from a session management network element, where the second indication information is used to instruct the second user plane network element to perform downlink through the first mapping rule The mapping between the application layer sequence number of the data packet and the GTP-U layer sequence number; wherein, the second user plane network element is the anchor point of the second PDU session; when receiving the second downlink data packet of the second PDU session, the first The second user plane network element performs mapping between the application layer sequence number of the second downlink data packet and the GTP-U layer sequence number according to the first mapping rule; the second user plane network element sends the second downlink data packet.
  • the second user plane network element can use the first mapping rule to map the application layer sequence number of the downlink data packet and the GTP-U layer sequence number, and the first user plane network element also adopts the first mapping rule.
  • the same mapping rule is used to map the application layer sequence number of the downlink data packet and the GTP-U layer sequence number, the synchronization of the data packet processing of the two access network devices can be realized, so as to ensure that the service communication is not interrupted, and the improvement is achieved.
  • the purpose of communication link reliability is used to map the application layer sequence number of the downlink data packet and the GTP-U layer sequence number.
  • the second indication information is further used to indicate the first mapping rule. This possible implementation manner can reduce signaling overhead compared to using other indication information to indicate the first mapping rule.
  • the method further includes: the second user plane network element receives the tunnel information of the first user plane network element from the session management network element, where the tunnel information of the first user plane network element includes the first user plane network element
  • the tunnel endpoint identifier and IP address of the network element, the first user plane network element is the anchor point of the first PDU session, and the first PDU session and the second PDU session are mutually redundant sessions; after receiving the uplink data of the first PDU session When the packet is received, the second user plane network element sends the uplink data packet of the first PDU session to the first user plane network element according to the tunnel information of the first user plane network element.
  • a communication method including: when the first access network device determines to start backup transmission, sending an application layer sequence number and a GTP-U layer sequence number used to instruct a downlink data packet to a session management network element The fourth indication information of the mapping between.
  • the method further includes: the first access network device sends third indication information to the terminal for instructing the terminal to only send uplink data packets on the first PDU session, and the terminal establishes the first PDU The session and the second PDU session communicate with the data network.
  • the terminal since the terminal does not send uplink data packets on the second PDU session, compared with sending uplink data packets on both PDU sessions, air interface signal interference can be avoided and air interface resources can be saved.
  • the method further includes: the first access network device discards the uplink data packets sent by the terminal through the second PDU session.
  • the storage space of the first access network device can be released, and the utilization rate of the storage space can be improved.
  • a communication method comprising: under the condition that the failure of the first access network device is not detected, the second access network device receives the first uplink data packet and the first uplink data packet and the first uplink data packet sent by the terminal through the first PDU session.
  • the second user plane network element sends the third downlink data packet through the second PDU session, and buffers the first uplink data packet and the third downlink data packet; in the case of detecting the failure of the first access network equipment, the second access network
  • the network device receives the second uplink data packet sent by the terminal through the first PDU session, and sends it to the second user plane network element; the second access network device receives the fourth downlink data packet sent by the second user plane network element through the second PDU session
  • the data packet is sent to the terminal; wherein, the first access network device and the second access network device have the same cell configuration, the terminal establishes the first PDU session and the second PDU session to communicate with the data network, and the first user plane network
  • the element and the second user plane network element are respectively the anchor points of the first PDU session and the second PDU session.
  • the first uplink data packet and the third downlink data packet are cached in the case of no failure of the first access network device being detected, and the first access network device can be taken over immediately in the event of a failure of the first access network device.
  • the first access network device implements fast switching between the first access network device and the second access network device.
  • a communication method comprising: in the case that the failure of the first access network device is not detected, the second access network device receives a third uplink data packet sent by the terminal through the first PDU session, and Discard the third uplink data packet; in the case of detecting the failure of the first access network device, the second access network device receives the fourth uplink data packet sent by the terminal through the second PDU session, and sends it to the second user plane network element; the second access network device receives the fifth downlink data packet sent by the second user plane network element through the second PDU session and sends it to the terminal; wherein the first access network device and the second access network device have the same Cell configuration, the terminal communicates with the data network through the first PDU session and the second PDU session, and the anchor points of the first PDU session and the second PDU session are the first user plane network element and the second user plane network element respectively.
  • the second access network device uses the second PDU session to transmit data, so as to implement fast switching between the first access network device and the second access network device , the switching delay of the first access network device and the second access network device is reduced, and the reliability of data transmission is improved.
  • the method further includes: in the case where the failure of the first access network device is not detected, the second access network device receives the fifth uplink data packet sent by the terminal through the second PDU session and The second user plane network element sends the sixth downlink data packet through the second PDU session, and buffers the fifth uplink data packet and the sixth downlink data packet.
  • the fifth uplink data packet and the sixth downlink data packet are cached, and the first access network device can take over immediately in the event of a failure of the first access network device.
  • the first access network device implements fast switching between the first access network device and the second access network device.
  • a communication method comprising: the terminal receiving third indication information from a first access network device or a session management network element for instructing the terminal to send uplink data packets only on the first PDU session, and the terminal is in the first PDU session.
  • the uplink data packet is sent on the first PDU session; wherein, the terminal establishes the first PDU session and the second PDU session to communicate with the data network, and the first PDU session and the second PDU session are mutually redundant sessions.
  • the terminal since the terminal does not send uplink data packets on the second PDU session, compared with sending uplink data packets on both PDU sessions, air interface signal interference can be avoided and air interface resources can be saved.
  • the method further includes: the terminal discarding the uplink data packets on the second PDU session according to the third indication information.
  • the method further includes: the terminal sends a first PDU session establishment request for requesting establishment of the first PDU session to the session management network element, where the first PDU session establishment request includes the information of the second PDU session logo.
  • the identifier of the second PDU session is used to indicate that the second PDU session and the first PDU session are mutually redundant sessions.
  • the session management network element can determine that the first PDU session and the second PDU session are mutually redundant sessions.
  • the method further includes: the terminal sends a second PDU session establishment request for requesting establishment of a second PDU session to the session management network element, where the second PDU session establishment request includes the first PDU session establishment request. logo.
  • the identifier of the first PDU session is used to indicate that the first PDU session and the second PDU session are mutually redundant sessions.
  • the session management network element can determine that the first PDU session and the second PDU session are mutually redundant sessions.
  • a communication device comprising: a processing unit and a communication unit; the processing unit is configured to send first indication information to a first user plane network element through the communication unit, where the first indication information is used to indicate the first user The plane network element performs the mapping between the application layer sequence number of the downlink data packet and the GTP-U layer sequence number according to the first mapping rule; the processing unit is further configured to send the second indication information to the second user plane network element through the communication unit, and the first The second indication information is used to instruct the second user plane network element to perform the mapping between the application layer sequence number of the downlink data packet and the GTP-U layer sequence number through the first mapping rule; wherein, the terminal establishes the first PDU session and the second PDU session.
  • the first user plane network element and the second user plane network element are the anchor points of the first PDU session and the second PDU session, respectively, and the access network equipment accessed by the terminal includes the first access network equipment and the first access network equipment.
  • Two access network devices, the first access network device and the second access network device have the same cell configuration; wherein, the application layer sequence number of the first downlink data packet received at the first user plane network element is the same as the first access network device.
  • the GTP-U layer sequence of the first downlink data packet sent by the first user plane network element to the first access network device The number is the same as the GTP-U layer sequence number of the second downlink data packet sent by the second user plane network element to the second access network device.
  • the first indication information and the second indication information are further used to indicate the first mapping rule.
  • the processing unit is further configured to send third indication information to the terminal through the communication unit, where the third indication information is used to instruct the terminal to send uplink data packets only on the first PDU session.
  • the processing unit is further configured to instruct the first access network device to process the first PDU session through the communication unit.
  • the processing unit is further configured to receive the tunnel information of the first user plane network element from the first user plane network element through the communication unit, where the tunnel information of the first user plane network element includes the first user plane network element The tunnel endpoint identifier and IP address of the network element; the processing unit is further configured to send the tunnel information of the first user plane network element to the second user plane network element through the communication unit, which is used for the second user plane network element according to the first user plane network element.
  • the tunnel information of the network element forwards the uplink data packet of the first PDU session to the first user plane network element.
  • the processing unit is further configured to receive fourth indication information from the first access network device through the communication unit, where the fourth indication information is used to indicate the application layer sequence number and GTP- Mapping of U-layer serial numbers.
  • the processing unit is further configured to receive a first PDU session establishment request from the terminal through the communication unit, where the first PDU session establishment request is used to request the establishment of the first PDU session; in the first PDU session establishment request
  • the processing unit is specifically configured to send the first indication information to the first user plane network element through the communication unit.
  • the processing unit is further configured to receive a second PDU session establishment request from the terminal through the communication unit, where the second PDU session establishment request is used to request the establishment of the second PDU session; in the second PDU session establishment request
  • the processing unit is specifically configured to send the second indication information to the second user plane network element through the communication unit.
  • a communication device comprising: a processing unit and a communication unit; the communication unit is configured to receive second indication information from a session management network element, where the second indication information is used to instruct the communication device to perform a mapping operation through the first mapping rule The mapping between the application layer sequence number of the downlink data packet and the GTP-U layer sequence number; wherein, the communication device is the anchor point of the second PDU session; when receiving the second downlink data packet of the second PDU session, the processing unit, using for mapping the application layer sequence number of the second downlink data packet and the GTP-U layer sequence number according to the first mapping rule; the communication unit is also used for sending the second downlink data packet.
  • the second indication information is further used to indicate the first mapping rule.
  • the communication unit is further configured to receive tunnel information of the first user plane network element from the session management network element, where the tunnel information of the first user plane network element includes a tunnel endpoint of the first user plane network element ID and IP address, the first user plane network element is the anchor point of the first PDU session, and the first PDU session and the second PDU session are mutually redundant sessions; when receiving the uplink data packet of the first PDU session, the communication unit , and is further configured to send the uplink data packet of the first PDU session to the first user plane network element according to the tunnel information of the first user plane network element.
  • a communication device comprising: a processing unit and a communication unit; when it is determined to start backup transmission, the processing unit is configured to send fourth indication information to a session management network element through the communication unit, and the fourth indication information is used for It is used to instruct the mapping between the application layer sequence number of the downlink data packet and the GTP-U layer sequence number.
  • the processing unit is further configured to send third indication information to the terminal through the communication unit, where the third indication information is used to instruct the terminal to send uplink data packets only on the first PDU session, and the terminal establishes the first A PDU session and a second PDU session communicate with the data network.
  • the processing unit is further configured to discard the uplink data packets sent by the terminal through the second PDU session.
  • a communication apparatus including: a processing unit and a communication unit; in the case where a failure of the first access network device is not detected, the processing unit is configured to receive, through the communication unit, a transmission sent by a terminal through a first PDU session The first uplink data packet and the third downlink data packet sent by the second user plane network element through the second PDU session, and buffer the first uplink data packet and the third downlink data packet; wherein, the first access network equipment and communication The device has the same cell configuration, the terminal establishes a first PDU session and a second PDU session to communicate with the data network, and the first user plane network element and the second user plane network element are the anchors of the first PDU session and the second PDU session, respectively.
  • the processing unit is further configured to receive, through the communication unit, the second uplink data packet sent by the terminal through the first PDU session, and send it to the second user plane network element;
  • the processing unit is further configured to receive, through the communication unit, the fourth downlink data packet sent by the second user plane network element through the second PDU session, and send it to the terminal.
  • a communication apparatus comprising: a processing unit and a communication unit; in the case where a failure of the first access network device is not detected, the processing unit is configured to receive, through the communication unit, a terminal through the first PDU session The third uplink data packet is sent, and the third uplink data packet is discarded; wherein, the first access network device and the communication device have the same cell configuration, the terminal communicates with the data network through the first PDU session and the second PDU session, and the first access network device and the communication device have the same cell configuration.
  • the anchor points of a PDU session and a second PDU session are the first user plane network element and the second user plane network element respectively; in the case of detecting the failure of the first access network equipment, the processing unit is further configured to pass the communication unit receiving the fourth uplink data packet sent by the terminal through the second PDU session and sending it to the second user plane network element; the processing unit is further configured to receive, through the communication unit, the fifth uplink data packet sent by the second user plane network element through the second PDU session Downlink data packets and send to the terminal.
  • the processing unit is further configured to receive, through the communication unit, the fifth uplink data packet and the second uplink data packet sent by the terminal through the second PDU session.
  • the user plane network element sends the sixth downlink data packet through the second PDU session, and buffers the fifth uplink data packet and the sixth downlink data packet.
  • a twelfth aspect provides a communication apparatus, including: a processing unit and a communication unit; the processing unit is configured to receive, through the communication unit, third indication information from a first access network device or a session management network element, the third indication information is used to instruct the communication device to send the uplink data packet only on the first PDU session, the communication device establishes the first PDU session and the second PDU session to communicate with the data network, and the first PDU session and the second PDU session are mutually redundant sessions; The processing unit is further configured to send an uplink data packet on the first PDU session through the communication unit.
  • the processing unit is further configured to discard the uplink data packets on the second PDU session according to the third indication information.
  • the processing unit is further configured to send a first PDU session establishment request to the session management network element through the communication unit, where the first PDU session establishment request is used to request the establishment of a first PDU session, and the first PDU session The establishment request includes the identifier of the second PDU session.
  • the identifier of the second PDU session is used to indicate that the second PDU session and the first PDU session are mutually redundant sessions.
  • the processing unit is further configured to send a second PDU session establishment request to the session management network element through the communication unit, where the second PDU session establishment request is used to request the establishment of a second PDU session, and the second PDU session establishment request is used to request the establishment of a second PDU session.
  • the establishment request includes the identifier of the first PDU session.
  • the identifier of the first PDU session is used to indicate that the first PDU session and the second PDU session are mutually redundant sessions.
  • a communication apparatus including: a processor.
  • the processor is connected to the memory, the memory is used to store computer-executed instructions, and the processor executes the computer-executed instructions stored in the memory, thereby implementing any one of the methods provided in any one of the first to sixth aspects.
  • the memory and the processor may be integrated together, or may be independent devices. In the latter case, the memory may be located in the communication device or outside the communication device.
  • the processor includes a logic circuit, and also includes an input interface and/or an output interface.
  • the output interface is used for performing the sending action in the corresponding method
  • the input interface is used for performing the receiving action in the corresponding method.
  • the communication device further includes a communication interface and a communication bus, and the processor, the memory and the communication interface are connected through the communication bus.
  • the communication interface is used to perform the actions of transceiving in the corresponding method.
  • the communication interface may also be referred to as a transceiver.
  • the communication interface includes at least one of a transmitter and a receiver. In this case, the transmitter is configured to perform the sending action in the corresponding method, and the receiver is configured to perform the receiving action in the corresponding method.
  • the communication device exists in the form of a chip product.
  • a fourteenth aspect provides a communication device, comprising: a processor and an interface, the processor is coupled to a memory through the interface, and when the processor executes a computer program in the memory or the computer executes instructions, the first to sixth aspects are made Any one of the methods provided by any of the aspects is performed.
  • a fifteenth aspect provides a computer-readable storage medium, comprising computer-executable instructions, which, when the computer-executable instructions are run on a computer, cause the computer to execute any one of the first to sixth aspects. a method.
  • a sixteenth aspect provides a computer program product comprising computer-executable instructions that, when the computer-executable instructions are run on a computer, cause the computer to perform any one of the methods provided in any one of the first to sixth aspects .
  • a seventeenth aspect provides a communication system, including: a session management network element, a first user plane network element, a second user plane network element, a first access network device, and a second access network provided by the above aspects One or more of device and terminal.
  • 1 is a schematic diagram of communication between a terminal and a DN
  • Fig. 2 is a kind of network architecture composition schematic diagram
  • FIG. 3 is a schematic diagram of a PDU session
  • FIG. 4 is a schematic diagram of a communication scenario provided by an embodiment of the present application.
  • FIG. 5 is a flowchart of a communication method provided by an embodiment of the present application.
  • FIG. 6 is a flowchart of another communication method provided by an embodiment of the present application.
  • FIG. 7 is a flowchart of another communication method provided by an embodiment of the present application.
  • FIG. 8 is a flowchart of another communication method provided by an embodiment of the present application.
  • FIG. 9 is a schematic diagram of another communication scenario provided by an embodiment of the present application.
  • FIG. 11 is a flowchart of another communication method provided by an embodiment of the present application.
  • FIG. 14 is a flowchart of still another communication method provided by an embodiment of the present application.
  • FIG. 15 is a schematic diagram of the composition of a communication device provided by an embodiment of the present application.
  • FIG. 16 is a schematic diagram of a hardware structure of a communication device provided by an embodiment of the present application.
  • FIG. 17 is a schematic diagram of a hardware structure of another communication apparatus provided by an embodiment of the present application.
  • words such as “first” and “second” are used to distinguish the same or similar items with basically the same function and effect.
  • words “first”, “second” and the like do not limit the quantity and execution order, and the words “first”, “second” and the like are not necessarily different.
  • the technical solutions in the embodiments of the present application can be applied to the fourth generation (4th Generation, 4G) system, various systems based on 4G system evolution, fifth generation (5G) systems, and various systems based on 5G system evolution .
  • the 4G system may also be called an evolved packet system (EPS).
  • the core network (CN) of the 4G system may be called an evolved packet core (EPC), and the access network may be called long term evolution (LTE).
  • LTE long term evolution
  • the core network of the 5G system can be called 5GC (5G core), and the access network can be called new radio (NR).
  • 5G core 5GC
  • NR new radio
  • the present application is exemplified below by taking the application of the present application to a 5G system as an example.
  • the network elements involved in the present application may be replaced with network elements having the same or similar functions in the corresponding communication system.
  • FIG. 2 exemplarily shows a schematic diagram of a network architecture of a 5G system.
  • the 5G system may include: an authentication server function (AUSF) network element, an access and mobility management function (AMF) network element, a DN, a unified data management (unified) data management, UDM) network element, policy control function (policy control function, PCF) network element, (radio) access network ((radio) access network, (R)AN) network element, UPF network element, terminal (terminal) , an application function (AF) network element, and a session management function (session management function, SMF) network element.
  • AUSF authentication server function
  • AMF access and mobility management function
  • UDM unified data management
  • PCF policy control function
  • PCF policy control function
  • R radio access network
  • terminal terminal
  • AF application function
  • SMF session management function
  • (R)AN network element AMF network element, SMF network element, UDM network element, UPF network element, PCF network element, etc. are referred to by RAN, AMF, SMF, UDM, UPF, PCF, etc. respectively. .
  • the 5G system is divided into two parts: the access network and the core network.
  • the access network is used to implement functions related to wireless access, mainly including the RAN.
  • the core network is used for network service control, data transmission, etc.
  • the core network consists of multiple network elements, mainly including: AMF, SMF, UPF, PCF, UDM, etc.
  • PCF is responsible for providing policies to AMF and SMF, such as quality of service (QoS) policies, slice selection policies, etc.
  • QoS quality of service
  • UDM for processing 3rd generation partnership project (3GPP) authentication and key agreement (AKA) authentication credentials, user identification processing, access authorization, registration/mobility management, subscription management , SMS management, etc.
  • 3GPP 3rd generation partnership project
  • AKA key agreement
  • AF which may be an application server, may belong to an operator or a third party. It mainly supports interaction with the 3GPP core network to provide services, such as influencing data routing decisions, policy control functions, or providing some third-party services to the network side.
  • AMF is mainly responsible for the signaling processing part, such as terminal registration management, terminal connection management, terminal reachability management, terminal access authorization and access authentication, terminal security function, terminal mobility management (such as terminal location update, terminal registration network, terminal switching, etc.), network slice selection, SMF selection, terminal registration or de-registration and other functions.
  • SMF is mainly responsible for the control plane functions of terminal session management, including UPF selection, control and redirection, Internet Protocol (IP) address allocation and management, session QoS management, and obtaining policy and charging control from PCF (policy and charging control, PCC) policy, bearer or session establishment, modification and release, etc.
  • IP Internet Protocol
  • PCC policy and charging control
  • UPF as the anchor point of the protocol data unit (protocol data unit, PDU) session connection, is responsible for data packet filtering, data transmission/forwarding, rate control, generation of billing information, user plane QoS processing, uplink transmission authentication, Transmission level verification, downlink data packet buffering, and downlink data notification triggering, etc.
  • the UPF can also act as a branch point for a multi-homed PDU session.
  • the transmission resources and scheduling functions that serve the terminal in the UPF are managed and controlled by the SMF.
  • RAN a network composed of one or more access network devices (also referred to as RAN nodes or network devices), implements radio physical layer functions, resource scheduling and radio resource management, radio access control and mobility management functions, services Features such as quality management, data compression and encryption.
  • the access network equipment is connected to the UPF through the user plane interface N3, and is used to transmit data of the terminal.
  • the access network equipment establishes a control plane signaling connection with the AMF through the control plane interface N2 to implement functions such as radio access bearer control.
  • the access network equipment may be a base station, a wireless fidelity (WiFi) access point (AP), a worldwide interoperability for microwave access (WiMAX) site, and the like.
  • the base station may include various forms of base stations, such as: a macro base station, a micro base station (also called a small station), a relay station, an access point, and the like.
  • an AP in a wireless local area network WLAN
  • a base station in the global system for mobile communications (GSM) or code division multiple access (CDMA) base transceiver station, BTS
  • a base station NodeB, NB
  • WCDMA wideband code division multiple access
  • evolved node B, eNB or eNodeB in LTE
  • relay stations or access points or in-vehicle devices, wearable devices, and the next generation node B (gNB) in the future 5G system or the public land mobile network (PLMN) evolved in the future ) base stations in the network, etc.
  • gNB next generation node B
  • PLMN public land mobile network
  • the terminal may be a wireless terminal, or may also be a wired terminal.
  • a wireless terminal may be a device that provides voice and/or data connectivity to a user, a handheld device with wireless connectivity, or other processing device connected to a wireless modem.
  • a certain air interface technology (such as NR technology or LTE technology) is used between the terminal and the access network device to communicate with each other.
  • a certain air interface technology (such as NR technology or LTE technology) can also be used between terminals to communicate with each other.
  • a wireless terminal may communicate with one or more core network devices via access network devices, such as with AMF, SMF, and the like.
  • the wireless terminal may be a mobile terminal (eg, a mobile phone), a smart phone, a satellite wireless device, a wireless modem card, a computer with a mobile terminal (eg, laptop, portable, pocket, handheld, computer built-in, or vehicle mounted mobile devices), personal communication service (PCS) phones, cordless phones, session initiation protocol (SIP) phones, wireless local loop (WLL) stations, personal digital assistants (personal digital assistants) , PDA), virtual reality (VR) glasses, augmented reality (AR) glasses, machine type communication terminals, IoT terminals, roadside units (RSUs), communications on-board drones equipment, etc.
  • a wireless terminal may also be referred to as user equipment (UE), terminal equipment, subscriber unit, subscriber station, mobile station, mobile station, remote station ), access point, access terminal, user terminal, user agent, etc.
  • DN refers to an operator network that provides data transmission services for users, such as an IP multi-media service (IMS) network, the Internet, and the like.
  • the terminal accesses the DN by establishing a PDU session (PDU session) from the terminal to the access network device to the UPF to the DN.
  • PDU session is a connection between a terminal and a DN for providing PDU connection services.
  • the PDU session type may be an IP connection, an Ethernet connection, or an unstructured data connection.
  • the PDU connection service supported by the core network of the 5G system refers to the service that provides PDU exchange between the terminal and the DN determined by the data network name (DNN).
  • DNN data network name
  • a terminal can initiate the establishment of one or more PDU sessions to connect to the same DN or to different DNs. For example, in FIG. 3, the terminal initiates the establishment of PDU Session 1 and PDU Session 2 to connect to the same DN.
  • the network architecture of the 5G network may also include other functional network elements.
  • a network exposure function network exposure function, NEF, etc.
  • a network element may also be referred to as an entity or a device or the like.
  • the terminal can establish two PDU sessions, namely the first PDU session and the second PDU session, and the anchor point of the first PDU session is the first UPF (that is, the first PDU session The data packet needs to pass through the first UPF), and the anchor point of the second PDU session is the second UPF (that is, the data packet of the second PDU session needs to pass through the second UPF).
  • the data packets may also be called service packets.
  • the second access network device may serve as a backup station for the first access network device, so that when the first access network device fails, the second access network device It can ensure that service communication is not interrupted, thereby improving the reliability of the entire communication link.
  • the first access network device and the second access network device may have the same frequency deployment, or may have different frequency deployments.
  • the first access network device and the second access network device may back up the full bandwidth, or may share part of the spectrum. For example, consider a spectral bandwidth of 100 megahertz (MHz).
  • the first access network device can work using the first 50 MHz, and the second access network device can be backed up by the second 50 MHz.
  • the second access network device can use the first 50 MHz to back up the first access network device, and the second 50 MHz can provide services to other terminals.
  • the identifiers of the first access network device and the second access network device may be the same or different.
  • the second access network device may acquire the cell configuration parameters of the first access network device from the first access network device.
  • the second access network device can perform cell configuration according to the cell configuration parameters of the first access network device, so as to achieve the same cell configuration and coverage, so that when the first access network device fails, the second access network device can The switching of the service communication of the terminal is realized without delay and without packet loss.
  • the terminal only one logical access network device can be seen, and the first access network device and the second access network device cannot be distinguished. Since the second access network device and the first access network device have the same cell configuration and coverage, both the first access network device and the second access network device can send the uplink data packets sent by the terminal through the first PDU session.
  • the uplink data packet sent by the terminal through the second PDU session can also be received by the first access network device and the second access network device.
  • the DN will generate two downlink data packets, and send them to the first UPF and the second UPF through the first PDU session and the second PDU session respectively, and the application layer sequence numbers of the two downlink data packets are the same.
  • the tunnel information of the first access network device and the second access network device are different.
  • the first UPF sends the downlink data packet of the first PDU session to the first access network device according to the tunnel information of the first access network device, and the second access network device.
  • the UPF sends the downlink data packet of the second PDU session to the second access network device according to the tunnel information of the second access network device.
  • the second access network device may also pre-establish a data transmission channel with the AMF and the UPF, so that when the first access network device fails, the second access network device can implement service communication with the core network device without delay and packet loss switch. In this way, it can be ensured that when the first access network device fails, the second access network device can quickly and accurately take over related services, ensuring high-quality transmission of service communication, and improving the reliability of the communication link.
  • the first access network device can also realize the synchronous configuration between the first access network device and the second access network device through interaction with the second access network device, so that the first access network device appears in the first access network device.
  • the second access network device can smoothly take over the related services of the first access network device, ensuring smooth business communication.
  • the synchronization configuration may include one or more configurations of the following information: the context of the first PDU session, the context of the second PDU session, the information of the access network device processing the first PDU session, the Information of access network equipment, access stratum (AS) context, core network context, mobility management (mobility management, MM) context, AS key, non-access stratum (non-access-stratum, NAS)
  • the secret key, and at least one item of information such as the corresponding security algorithm, etc., may also include at least one item of radio resource control (radio resource control, RRC) information, and at least one item of layer 2 (layer 2, L2) information.
  • RRC radio resource control
  • the context of the PDU session may include the sequence numbers of packets that have been transmitted by different service flows or QoS flows in the PDU session, or the sequence numbers of the packets to be transmitted.
  • the specific sequence number may be a packet data convergence protocol (packet data convergence protocol).
  • solution 1 solutions 1 and solution 2
  • the terminal only sends uplink data packets through the first PDU session.
  • the DN (specifically, the service server in the DN) sends downlink data packets through the first PDU session and the second PDU session.
  • the first UPF and the second UPF use the same mapping rule to perform the application layer sequence number (sequence number, SN) of the downlink data packets and the general packet radio service tunneling protocol user plane.
  • GTP-U general packet radio service tunneling protocol user plane
  • (a) in FIG. 4 shows the communication path of the first access network device when no failure occurs.
  • the first access network device sends the received uplink data packet to the first UPF, and the first UPF sends it again Give DN.
  • the DN sends the downlink data packet through the first PDU session
  • the first UPF sends the received downlink data packet to the first access network device, and the first access network device sends it to the terminal.
  • the second access network device receives the uplink data packet.
  • the second access network device may not forward the uplink data of the first PDU session to the second UPF Bag.
  • the second UPF sends the downlink data packet to the second access network device.
  • the second access network device may not send the received downlink data packet of the second PDU session to the terminal .
  • (b) in FIG. 4 shows a communication path of the first access network device when a failure occurs.
  • path 1 in (b) of FIG. 4 since the first access network device fails, path 1 can no longer be used for data transmission.
  • the second UPF sends the received downlink data packet to the second access network device, and the second access network device sends it to the terminal.
  • the uplink data packet refer to path 3 in (b) of FIG.
  • the second access network device receives the uplink data packet and sends it to the second UPF, because The anchor point of the first PDU session is the first UPF, therefore, the second UPF sends the uplink data packet to the first UPF, and the first UPF then sends the packet to the DN.
  • the communication method provided by solution 1 includes:
  • the SMF sends first indication information to the first UPF, where the first indication information is used to instruct the first UPF to perform mapping between the application layer sequence number of the downlink data packet and the GTP-U layer sequence number by using the first mapping rule.
  • the first UPF receives the first indication information from the SMF.
  • the terminal establishes a first PDU session and a second PDU session to communicate with the DN, and the access network devices accessed by the terminal include the first access network device and the second access network device, the first access network device and the second access network device.
  • the access network equipment has the same cell configuration. Since the first access network device and the second access network device have the same cell configuration, the first PDU session and the second PDU session are mutually redundant sessions.
  • the redundant session refers to a session that transmits the same uplink application layer data and downlink application layer data.
  • the first UPF is the anchor point of the first PDU session.
  • the protocol adopted by the application layer of the downlink data packet may be an application layer redundancy protocol.
  • the application layer redundancy protocol can be high-availability seamless redundancy protocol (HSR), parallel redundancy protocol (parallel redundancy protocol, PRP) and frame redundancy replication and deduplication (frame replication and elimination for reliability). , FRER) etc.
  • the GTP-U layer refers to the protocol layer used for tunnel transmission between the access network device and the UPF.
  • the specific protocol layer of this function may also have other names, which are not described in this application. limit.
  • the first indication information is further used to indicate the first mapping rule.
  • the first mapping rule may also be preset or indicated by other indication information, which is not limited in this application.
  • the first mapping rule may be to set the GTP-U layer sequence number to the application layer sequence number of the received downlink data packet. For example, if the application layer sequence number is 00000000 00010001, then the GTP-U layer sequence number Also set to 00000000 00010001.
  • the first mapping rule may take the application layer serial number as an input parameter and substitute it into a preset function to determine the GTP-U layer serial number corresponding to the application layer serial number.
  • the first mapping rule may be to use the application layer serial number and the quality of service flow indicator (QFI) as input parameters, and substitute them into a preset function to determine the corresponding application layer serial number.
  • QFI quality of service flow indicator
  • the SMF sends second indication information to the second UPF, where the second indication information is used to instruct the second UPF to perform mapping between the application layer sequence number of the downlink data packet and the GTP-U layer sequence number by using the first mapping rule.
  • the second UPF receives the second indication information from the SMF.
  • the second UPF is the anchor point of the second PDU session.
  • the second indication information is further used to indicate the first mapping rule.
  • the first mapping rule may also be preset or indicated by other indication information, which is not limited in this application.
  • the first UPF When receiving the first downlink data packet of the first PDU session (that is, the first downlink data packet sent by the DN through the first PDU session), the first UPF performs the first downlink data packet according to the first mapping rule.
  • the first UPF sends the first downlink data packet to the first access network device.
  • the second UPF When receiving the second downlink data packet of the second PDU session (that is, the second downlink data packet sent by the DN through the second PDU session), the second UPF performs the application layer of the second downlink data packet according to the first mapping rule. Mapping of sequence numbers and GTP-U layer sequence numbers.
  • the second UPF sends a second downlink data packet to the second access network device.
  • the first UPF accesses the first The GTP-U layer sequence number of the first downlink data packet sent by the network device is the same as the GTP-U layer sequence number of the second downlink data packet sent by the second UPF to the second access network device.
  • the GTP-U layer sequence number of the downlink data packet is mapped to a PDCP layer sequence number and sent to the terminal.
  • the method for mapping the first access network device and/or the second access network device to the PDCP layer sequence number according to the GTP-U layer sequence number of the downlink data packet may be:
  • Method 1 The first access network device and/or the second access network device takes the serial number of the GTP-U layer as an input parameter and substitutes it into a preset function to determine the serial number of the PDCP layer.
  • Method 2 The first access network device and/or the second access network device uses the serial number and QFI of the GTP-U layer as input parameters, and substitutes them into a preset function to determine the serial number of the PDCP layer.
  • the first UPF and the second UPF can use the same mapping rule to map the application layer sequence number of the downlink data packet and the GTP-U layer sequence number, so that the first UPF received
  • the application layer sequence number of the upstream data packet is the same as the application layer sequence number of the second downstream data packet received by the second UPF
  • the GTP of the first downstream data packet sent by the first UPF to the first access network device is the same as the sequence number of the GTP-U layer of the second downlink data packet sent by the second UPF to the second access network device, so as to realize the synchronization of the data packet processing of the two access network devices (that is, to realize the synchronization of the two access network devices).
  • the synchronization of each access network device on the user plane packets so as to ensure that the service communication is not interrupted and achieve the purpose of improving the reliability of the communication link.
  • the SMF may perform step 501 and/or step 502 when any one or more of the following conditions 1 to 3 are satisfied.
  • the SMF receives fourth indication information from the first access network device.
  • the fourth indication information is used to indicate any one or more of the following information:
  • the first access network device supports dual connectivity, that is, there is a second access network device in the network that matches the first access network device, and the second access network device and the first access network device have the same cell configuration.
  • the first access network device determines to start backup transmission, that is, the first access network device determines to start the second access network device to perform backup transmission, and the second access network device and the first access network device have the same cell configuration.
  • the first access network device determines to start the backup transmission, it sends fourth indication information to the SMF through the AMF.
  • the purpose of backup transmission is to achieve high reliability of data transmission.
  • the first access network device may start the backup transmission by default, or may obtain the S-NSSAI and/or DNN corresponding to the first PDU session or the second PDU session, and the S-NSSAI and/or DNN are set to need to be started When backing up the transfer, be sure to start the backup transfer.
  • the S-NSSAI and/or DNN may be sent by the AMF to the first access network device in the process of establishing or modifying the first PDU session or the second PDU session.
  • S-NSSAI and/or DNN can be carried in N2 PDU Session Request (N2 PDU Session Request).
  • the S-NSSAI and/or DNN required to initiate backup transmission may be preset.
  • the SMF receives the first PDU session establishment request from the terminal, the first PDU session establishment request is used to request the establishment of the first PDU session, and the first PDU session establishment request includes the identifier of the second PDU session.
  • condition 2 the terminal sends a first PDU session establishment request to the SMF.
  • the identifier of the second PDU session is used to indicate that the second PDU session and the first PDU session are mutually redundant sessions.
  • the information used to indicate that the second PDU session and the first PDU session are mutually redundant sessions may also be other information in the first PDU session establishment request, which is not limited in this application.
  • the SMF receives a second PDU session establishment request from the terminal, the second PDU session establishment request is used to request the establishment of the second PDU session, and the second PDU session establishment request includes the identifier of the first PDU session.
  • condition 3 the terminal sends a second PDU session establishment request to the SMF.
  • the identifier of the first PDU session is used to indicate that the first PDU session and the second PDU session are mutually redundant sessions.
  • the information used to indicate that the first PDU session and the second PDU session are mutually redundant sessions may also be other information in the second PDU session establishment request, which is not limited in this application.
  • the SMF may perform step 501 and/or step 502 .
  • steps 500a corresponding to condition 1
  • 500b corresponding to condition 2
  • 500c corresponding to condition 3
  • the SMF may perform step 501 and/or step 501.
  • the SMF can perform step 501 and step 502 when condition 1 or condition 2 or condition 3 is satisfied, or perform step 501 when condition 2 is satisfied, and perform step when condition 3 is satisfied. 502.
  • the method further includes:
  • Step 507 includes step 507a or step 507b.
  • Step 507a means that the first access network device sends third indication information to the terminal, and the terminal receives the third indication information from the first access network device.
  • Step 507b means that the SMF sends the third indication information to the terminal through the first access network device, and the terminal receives the third indication information from the SMF through the first access network device.
  • the terminal sends an uplink data packet on the first PDU session. Specifically, the terminal may only send the uplink data packet on the first PDU session according to the third indication information.
  • the method further includes:
  • the terminal discards the uplink data packet on the second PDU session according to the third indication information; or, the terminal does not generate the uplink data packet on the second PDU session according to the third indication information. Specifically, the terminal may discard the uplink data packet after the PDCP layer corresponding to the second PDU session generates, or the terminal may not generate the uplink data packet at the PDCP layer corresponding to the second PDU session.
  • the method further includes:
  • the SMF instructs the first access network device to process the first PDU session.
  • the first access network device processes the first PDU session according to the instruction.
  • the first access network device receives the uplink data packet sent by the terminal through the first PDU session, and sends it to the first UPF, and the first UPF sends it to the DN.
  • the DN sends the downlink data packet to the first UPF through the first PDU session, the first UPF sends the downlink data packet to the first access network device, and the first access network device sends it to the terminal.
  • the method further includes:
  • the second access network device receives the first uplink data packet sent by the terminal through the first PDU session and the third data packet sent by the second UPF through the second PDU session. downlink data packets, and buffer the first uplink data packet and the third downlink data packet.
  • Step 801 includes step 801a, step 801b and step 801c.
  • Step 801a is: the terminal sends the first uplink data packet through the first PDU session, and the second access network device receives the first uplink data packet.
  • Step 801b is: the second UPF sends the third downlink data packet to the second access network device through the second PDU session, and the second access network device receives the third downlink data packet.
  • Step 801c is: the second access network device buffers the first uplink data packet and the third downlink data packet.
  • the second access network device receives the second uplink data packet sent by the terminal through the first PDU session, and sends it to the second UPF; the second access network device The fourth downlink data packet sent by the second UPF through the second PDU session is received and sent to the terminal.
  • Step 802 includes step 802a, step 802b, steps 802c and 802d.
  • Step 802a is: the terminal sends the second uplink data packet through the first PDU session, and the second access network device receives the second uplink data packet.
  • Step 802b is: the second access network device sends the second uplink data packet to the second UPF, and the second UPF receives the second uplink data packet.
  • Step 802c is: the second UPF sends the fourth downlink data packet to the second access network device through the second PDU session, and the second access network device receives the fourth downlink data packet.
  • Step 802d is: the second access network device sends a fourth downlink data packet to the terminal.
  • the second access network device determines, according to the context of the first PDU session acquired from the first access network device, Upstream data packets that need to be sent to the second UPF.
  • the second access network device obtains, from the context of the first PDU session, the PDCP layer sequence of the last uplink data packet of the first QoS flow of the first PDU session sent by the first access network device to the first UPF.
  • the second access network device determines that the PDCP sequence number of the uplink data packet of the first QoS flow of the first PDU session to be sent to the second UPF is x+1, and after encapsulating the data packet into a GTP-U data packet Sent to the second UPF.
  • the first access network device will process the uplink data packets sent by the terminal through the first PDU session and the first UPF through the first PDU session. Downlink data packets.
  • the second access network device does not need to process the uplink data packets or downlink data packets. Therefore, the second access network device can buffer the uplink data packets or downlink data packets. After the buffering time reaches a certain time Discard upstream or downstream packets. Specifically, a buffer timer (timer) may be set, and when the timer expires, the uplink data packet or the downlink data packet is discarded.
  • the method further includes:
  • the SMF receives the tunnel information of the first UPF from the first UPF, where the tunnel information includes the tunnel endpoint identifier and the IP address of the first UPF.
  • the SMF sends the tunnel information of the first UPF to the second UPF, and configures a routing rule for the second UPF to forward the uplink data packet of the first PDU session to the first UPF according to the tunnel information and the routing rule.
  • the second UPF receives the tunnel information and routing rules of the first UPF from the SMF.
  • the routing rule includes description information of a service associated with the uplink data packet of the first PDU session, for example, it may be an IP quintuple.
  • the second UPF forwards the uplink data packet to the first UPF according to the tunnel information of the first UPF if it matches the service description information in the routing rule.
  • the second UPF When receiving the uplink data packet of the first PDU session, the second UPF sends the uplink data packet of the first PDU session to the first UPF according to the tunnel information of the first UPF.
  • the second access network device receives the uplink data packet sent by the terminal through the first PDU session, and sends it to the second UPF, because the first PDU session
  • the anchor point of the first UPF is the first UPF. Therefore, the second UPF needs to send the uplink data packet of the first PDU session to the first UPF through the tunnel between the second UPF and the first UPF, and the first UPF sends the first UPF to the DN. Upstream packets of a PDU session.
  • the second UPF needs to learn the tunnel information of the first UPF, so as to send the uplink data packet of the first PDU session to the first UPF through the tunnel corresponding to the tunnel information of the first UPF.
  • the uplink data packet of the first PDU session sent by the second access network device to the second UPF may be sent through a tunnel between the second access network device and the second UPF for the first PDU session, That is to say, the tunnels used for transmitting the first PDU session and the second PDU session between the second access network device and the second UPF may be different.
  • the terminal sends uplink data packets through the first PDU session and the second PDU session.
  • the DN (specifically, the service server in the DN) sends downlink data packets through the first PDU session and the second PDU session.
  • the first UPF and the second UPF use the same mapping rule to map the application layer sequence number of the downlink data packet and the GTP-U layer sequence number, so as to ensure that the DN is sent.
  • the downlink data packets with the same application layer sequence number, the downlink data packets received by the first access network device and the downlink data packets received by the second access network device have the same GTP-U layer sequence number, realizing two accesses. Synchronization of data packet processing of network equipment, so as to ensure uninterrupted business communication and achieve the purpose of improving the reliability of communication links.
  • (a) in FIG. 9 shows the communication path of the first access network device when no failure occurs.
  • the first access network device sends the received uplink data packet to the first UPF, and the first UPF sends it again Give DN.
  • the DN sends the downlink data packet through the first PDU session
  • the first UPF sends the received downlink data packet to the first access network device, and the first access network device sends it to the terminal.
  • the first access network device discards the received uplink data packet.
  • the second access network device receives the uplink data packet.
  • the second access network device receives the uplink data packet and buffers the uplink data packet. Since the second access network device will buffer the uplink data packets of the second PDU session, the second access network device may discard the uplink data packets of the first PDU session.
  • the second UPF sends the downlink data packet to the second access network device. At this time, since the first access network device will send the received downlink data packet of the first PDU session to the terminal, the second access network device may not send the received downlink data packet of the second PDU session to the terminal .
  • (b) in FIG. 9 shows a communication path of the first access network device when a failure occurs.
  • path 1 and path 2 in (b) of FIG. 9 since the first access network device fails, path 1 and path 2 can no longer be used to transmit data.
  • Path 3 in (b) of FIG. 9 after the DN sends the downlink data packet through the second PDU session, the second UPF sends the received downlink data packet to the second access network device, and the second The access network equipment sends it to the terminal.
  • the second access network device After the terminal sends the uplink data packet through the second PDU session, the second access network device receives the uplink data packet, and sends the uplink data packet to the second UPF, and the second UPF sends the uplink data packet to the DN.
  • the second access network device receives the uplink data packet, because the second access network device forwards the data of the second PDU session Uplink data packets, therefore, the uplink data packets of the first PDU session can be discarded by the second access network device.
  • the second access network device processes the uplink data packets sent by the terminal through the second PDU session and the downlink data sent by the DN through the second PDU session. Bag.
  • the second UPF receives the uplink data packet of the second PDU session sent by the second access network device, and does not need to process the uplink data packet of the first PDU session. Therefore, steps 803 to 805 are not executed.
  • the first access network device can receive the uplink data packets of the second PDU session, but the first access network device does not process the uplink data packets of the second PDU session, the first access network device can The following actions are performed: the first access network device discards the uplink data packet sent by the terminal through the second PDU session.
  • the second access network device receives the third uplink data packet sent by the terminal through the first PDU session, and discards the third uplink data packet.
  • Step 1001 includes step 1001a and step 1001b.
  • Step 1001a is: the terminal sends the third uplink data packet through the first PDU session, and the second access network device receives the third uplink data packet sent by the terminal through the first PDU session.
  • Step 1001b is: the second access network device discards the third uplink data packet.
  • the second access network device receives the fourth uplink data packet sent by the terminal through the second PDU session, and sends it to the second UPF; the second access network device The fifth downlink data packet sent by the second UPF through the second PDU session is received and sent to the terminal.
  • Step 1002 includes steps 1002a, 1002b, 1002c and 1002d.
  • Step 1002a is: the terminal sends the fourth uplink data packet through the second PDU session, and the second access network device receives the fourth uplink data packet sent by the terminal through the second PDU session.
  • Step 1002b is: the second access network device sends the fourth uplink data packet to the second UPF, and the second UPF receives the fourth uplink data packet.
  • Step 1002c is: the second UPF sends the fifth downlink data packet to the second access network device through the second PDU session, and the second access network device receives the fifth downlink data packet.
  • Step 1002d is: the second access network device sends a fifth downlink data packet to the terminal.
  • the second access network device mainly processes the uplink data packets or downlink data packets of the second PDU session, and at this time, the terminal will also send the uplink data packets through the second PDU session.
  • the second access network device may discard the third uplink data packet.
  • the method further includes: in the case that the failure of the first access network device is not detected, the second access network device receives the fifth uplink data packet sent by the terminal through the second PDU session and The second UPF sends the sixth downlink data packet through the second PDU session, and buffers the fifth uplink data packet and the sixth downlink data packet.
  • Step 1003 includes step 1003a, step 1003b and step 1003c.
  • Step 1003a is: the terminal sends the fifth uplink data packet through the second PDU session, and the second access network device receives the fifth uplink data packet sent by the terminal through the second PDU session.
  • Step 1003b is: the second UPF sends the sixth downlink data packet through the second PDU session, and the second access network device receives the sixth downlink data packet sent by the second UPF through the second PDU session.
  • Step 1003c is: the second access network device buffers the fifth uplink data packet and the sixth downlink data packet.
  • the second access network device mainly processes the uplink data packets or downlink data packets of the second PDU session, after the second access network device receives the uplink data packets or downlink data packets of the second PDU session,
  • the uplink data packet or the downlink data packet can be buffered, and the uplink data packet or the downlink data packet can be discarded after the buffering time reaches a certain time.
  • the terminal associates the first PDCP entity with the second PDCP entity.
  • the first PDCP entity corresponds to the first PDU session
  • the second PDCP entity corresponds to the second PDU session.
  • the two associated PDCP entities assign the same PDCP layer sequence number to two uplink data packets carrying the same application layer data of the same service flow, and the terminal sends the two uplink data packets on the first PDU session and the second PDU session.
  • the terminal may generate the PDCP layer sequence number according to the application layer sequence number according to the second mapping rule, so as to ensure that the two uplink data packets of the same application layer data of the same service flow
  • Each uplink data packet is assigned the same PDCP layer sequence number.
  • the method for the terminal to map the PDCP layer sequence number according to the application layer sequence number may be:
  • Method 1 The terminal takes the application layer serial number as an input parameter, and substitutes it into a preset function to determine the PDCP layer serial number.
  • Method 2 The terminal takes the application layer serial number and the QFI as input parameters, and substitutes them into a preset function to determine the PDCP layer serial number.
  • the second mapping rule may be preconfigured on the terminal, or may be delivered to the terminal by the SMF through the first access network device and/or the second access network device during the session establishment process.
  • the second access network device may determine whether the first access network device is faulty in any one or more of the following ways 1 to 3.
  • the second access network device receives information from the terminal, and determines whether the first access network device is faulty according to the information fed back by the terminal.
  • the information may be a positive acknowledgment (Acknowledgement, ACK)/negative acknowledgment (Negative-Acknowledgment, NACK) fed back by the terminal.
  • ACK positive acknowledgment
  • NACK Negative-Acknowledgment
  • the terminal will perform ACK/NACK feedback according to information sent by the access network device (eg, the first access network device) that maintains communication with it. Since the second access network device is in a state capable of receiving information, the second access network device can receive ACK/NACK reported by multiple terminals that maintain communication with the first access network device. When the proportion of NACKs received by the second access network device in a certain period exceeds the first threshold (eg, 80%), the second access network device determines that the first access network device is faulty.
  • the first threshold eg, 80%
  • the second access network device receives measurement information from the terminal, and determines whether the first access network device is faulty according to the measurement information.
  • the first access network device sends first reference information, where the first reference information may be a channel status indication reference signal (CSI-RS), a channel status indication interference measurement (CSI-interference measurement, CSI) -IM), demodulation reference signal (demodulation reference signal, DMRS), one or more of cell reference signal (cell reference signal, CRS).
  • the terminal receives the first reference information sent by the first access network device, and performs measurement, and after the measurement, it can perform periodic reporting according to the configuration of the first access network device or based on an event.
  • the second access network device and the first access network device are in the same frequency and configuration, so they can receive the measurement result reported by the terminal.
  • the second access network device determines if the measurement value reported by the terminal is lower than a certain threshold.
  • the first access network device is faulty.
  • the second access network device may make the determination according to the reporting result of at least one terminal. If the specific terminal triggers the report according to the event, a second threshold value may be set, and the report is performed when the measurement result is lower than the value. Then, the second access network device may judge that the first access network device is faulty according to the result reported by at least one terminal. For example, take the first reference information as CSI-RS as an example. When the CSI-RS measurement result fed back by the second access network device from the terminal 1 and the terminal 2 is smaller than the second threshold, it is considered that there is a problem in the communication between the terminal and the first access network device, that is, the first access network device The device has failed.
  • the second access network device receives second reference information from the first access network device, and determines whether the first access network device is faulty according to the second reference information.
  • the second access network device may measure the second reference signal, and if the measurement result is lower than the third threshold, it is determined that the first access network device is faulty.
  • the second reference information may be the same as the first reference information.
  • the second access network device may measure according to the configuration of the second reference information sent by the first access network device.
  • the second access network device After the second access network device determines that the first access network device is faulty, it can take over the communication between the first access network device and the terminal. After the first UPF determines that the data of the first access network device is unreachable, it stops transmitting data to the first access network device. After the failure of the first access network device is removed and resumed to work, the first UPF can send data to the first access network device to resume dual-path transmission.
  • the first access network device and the second access network device are in a backup relationship with each other, and can maintain the current working state or switch to the state where the first access network device works and the second access network device is backed up after the fault is restored.
  • the access network device negotiates with the second access network device.
  • the first access network device can negotiate a point in time to take over the second access network device and stop working, or the first access network device can communicate with the second access network device.
  • a takeover instruction is sent, the second access network device stops working, and the first access network device continues to work.
  • the SMF may implement the foregoing solution 1 through a first PDU session establishment process and a second PDU session establishment process, which are exemplarily described below with reference to FIG. 11 and FIG. 12 respectively.
  • the first PDU session establishment process includes:
  • the terminal sends a first PDU session establishment request (PDU Session Establishment Request) to the AMF.
  • PDU Session Establishment Request PDU Session Establishment Request
  • the first PDU session establishment request is used to request the establishment of the first PDU session.
  • the first PDU session establishment request also includes the identifier of the second PDU session, thereby indicating that the second PDU session and the first PDU session are mutually redundant sessions.
  • the identifier of the second PDU session may be allocated by the terminal for the second PDU session in advance.
  • the AMF performs SMF selection (SMF selection).
  • the AMF sends a PDU session creation session context request (Nsmf_PDU Session_CreateSMContext Request) of the first PDU session to the SMF.
  • Nsmf_PDU Session_CreateSMContext Request a PDU session creation session context request
  • the PDU session creation session context request of the first PDU session is used for requesting to create a context of the first PDU session.
  • the request includes the identifier of the first PDU session and the identifier of the second PDU session sent by the terminal in step 1101, thereby indicating that the second PDU session and the first PDU session are mutually redundant sessions.
  • the SMF obtains the subscription information of the terminal from the UDM through a subscription retrieval (Subscription retrieval)/subscription for updates (Subscription for updates) process.
  • the SMF sends a PDU Session Create Session Context Response (Nsmf_PDU Session_CreateSMContext Response) of the first PDU session to the AMF.
  • Nsmf_PDU Session_CreateSMContext Response PDU Session Create Session Context Response
  • Each network element performs an authentication and authorization (PDU Session authentication/authorization) process of the first PDU session interactively.
  • PDU Session authentication/authorization PDU Session authentication/authorization
  • the SMF performs PCF selection, and initializes the joint establishment of the session management policy (SM Policy Association Establishment)/joint modification of the session management policy (SM Policy). Association Modification) process.
  • Policy Control and Charging Policy Control and Charging, PCC
  • Step 1107 includes steps 1107a and 1107b in FIG. 11 .
  • Step 1107a is: SMF performs PCF selection.
  • Step 1107b is: the SMF initializes the session management policy joint establishment/session management policy joint modification process.
  • the SMF performs UPF selection (UPF selection).
  • the UPF selected by the SMF is the first UPF.
  • the SMF initiates a session management policy joint modification process.
  • the SMF establishes an N4 session connection with the first UPF.
  • Step 1110 includes step 1110a and step 1110b.
  • Step 1110a is: the SMF sends an N4 session establishment/modification request (N4 Session Establishment/Modification Request) to the first UPF.
  • Step 1110b is: the first UPF sends an N4 session establishment/modification response (N4 Session Establishment/Modification Response) to the SMF.
  • the SMF requests the first UPF for the tunnel information of the first UPF (which may be recorded as the first tunnel information of the first UPF) for the first access network device to transmit the uplink data packet of the first PDU session,
  • the first UPF sends the first tunnel information of the first UPF to the SMF in step 1110b.
  • the SMF sends an N1N2 message (Namf_Communication__N1N2MessageTransfer) to the AMF.
  • N1N2 message (Namf_Communication__N1N2MessageTransfer)
  • the N1N2 message includes an N2 message, and the N2 message includes first tunnel information of the first UPF, which is used to establish an uplink N3 link, and also includes information instructing the first access network device to process the first PDU session.
  • the SMF may indicate to the first access network device that the first PDU session is the primary PDU session, and the first access network device processes the first PDU session after receiving the instruction of the SMF.
  • the SMF may send the seventh indication information to the first access network device, and the first access network device processes the first PDU session after receiving the seventh indication information.
  • the N1 N2 message also includes an N1 message, and optionally, the N1 message includes third indication information sent to the terminal, where the third indication information is used to instruct the terminal to send uplink data packets only on the first PDU session .
  • the SMF may determine to perform redundant processing on the PDU session. Specifically, the SMF may determine to perform redundant processing on the first PDU session and the second PDU session according to the information obtained in step 1103 that the first PDU session and the second PDU session are mutually redundant sessions. Alternatively, the SMF may also determine whether to perform redundancy processing on the PDU session according to the DNN or S-NSSAI corresponding to the first PDU session. Specifically, if the DNN or S-NSSAI corresponding to the first PDU session included in the PDU session creation session context request for the first PDU session received by the SMF is the DNN or S-NSSAI that needs to perform backup transmission, it is determined that the PDU session Do redundant processing.
  • the SMF may determine to perform redundancy processing on the PDU session when the first access network device has the capability of performing backup transmission.
  • the DNN or S-NSSAI, the information that the first PDU session and the second PDU session are mutually redundant sessions (for example, the identifiers of the first PDU session and the second PDU session), and whether the first access network device is capable of performing backup Information such as the transmission capability can be carried to the SMF in the PDU session creation session context request in step 1103 .
  • the information on whether the first access network device has the capability of performing backup transmission may be acquired by the AMF from the first access network device during the NG Setup (NG connection establishment) process.
  • the AMF sends an N2 PDU session request (N2_PDUSession_Request) to the first access network device.
  • N2_PDUSession_Request an N2 PDU session request
  • the N2 PDU session request includes the N2 message in step 1111, and optionally, also includes third indication information.
  • the first access network device allocates radio resources.
  • the first access network device may perform an AN-specific resource setup (AN-specific resource setup) process. Radio resources are allocated through this process, and a PDU Session Establishment accept (PDU Session Establishment accept) message is sent to the terminal in this process.
  • AN-specific resource setup Radio resources are allocated through this process, and a PDU Session Establishment accept (PDU Session Establishment accept) message is sent to the terminal in this process.
  • PDU Session Establishment accept PDU Session Establishment accept
  • the first access network device sends third indication information to the terminal.
  • the first access network device sends an N2 PDU Session Response (N2 PDU Session Response) to the AMF.
  • N2 PDU Session Response N2 PDU Session Response
  • the N2 PDU session response includes fourth indication information, and the fourth indication information is used to indicate the mapping of the application layer sequence number of the downlink data packet and the GTP-U layer sequence number.
  • the N2 PDU session response also includes tunnel information of the first access network device.
  • the first access network device may determine to start backup transmission. Specifically, the first access network device may start backup transmission by default, or the N2 PDU session request received in step 1112 may include the DNN or S-NSSAI corresponding to the first PDU session, and the DNN or S-NSSAI When it is a DNN or S-NSSAI that needs to perform backup transmission, be sure to start the backup transmission.
  • the AMF sends a PDU session update session context request (Nsmf_PDU Session_UpdateSMContext Request) of the first PDU session to the SMF.
  • Nsmf_PDU Session_UpdateSMContext Request a PDU session update session context request
  • the PDU session update session context request includes fourth indication information.
  • the PDU session update session context request further includes tunnel information of the first access network device.
  • the SMF executes the N4 session modification process.
  • the SMF sends the first indication information to the first UPF through the N4 session modification process, and the first indication information is used to instruct the first UPF to perform the application layer sequence number and GTP-U layer sequence number of the downlink data packet through the first mapping rule mapping.
  • the SMF also sends the tunnel information of the first access network device and the N4 session identifier to the first UPF through the N4 session modification procedure, thereby establishing the downlink N3 link.
  • the first indication information is further used to indicate the first mapping rule.
  • step 1116 includes step 1116a and step 1116b.
  • Step 1116a is: the SMF sends an N4 session modification request (N4 Session Modification Request) to the first UPF, and the N4 session modification request may include the first indication information.
  • Step 1116b is: the first UPF sends an N4 Session Modification Response (N4 Session Modification Response) to the SMF.
  • the SMF sends the PDU Session Update Session Context Response (Nsmf_PDU Session_UpdateSMContext Response) of the first PDU session to the AMF.
  • Nsmf_PDU Session_UpdateSMContext Response PDU Session Update Session Context Response
  • the second PDU session establishment process includes:
  • the terminal sends a second PDU session establishment request to the AMF.
  • the second PDU session establishment request is used for requesting establishment of a second PDU session.
  • the second PDU session establishment request also includes the identifier of the first PDU session, thereby indicating that the first PDU session and the second PDU session are mutually redundant sessions.
  • the AMF performs SMF selection.
  • the AMF sends a PDU session creation session context request of the second PDU session to the SMF.
  • the PDU session creation session context request of the second PDU session is used to request to create a context of the second PDU session.
  • the request includes the identifier of the first PDU session and the identifier of the second PDU session sent by the terminal in step 1201, thereby indicating that the second PDU session and the first PDU session are mutually redundant sessions.
  • the SMF obtains the subscription information of the terminal from the UDM through a subscription retrieval/subscription update process.
  • the SMF sends a response of the PDU session creation session context of the second PDU session to the AMF.
  • Each network element performs authentication and authorization of the second PDU session interactively.
  • the SMF performs PCF selection, and initializes the session management policy joint establishment/session management policy joint modification process.
  • Step 1207 includes steps 1207a and 1207b in FIG. 12 .
  • Step 1207a is: SMF performs PCF selection.
  • Step 1207b is: the SMF initializes the session management policy joint establishment/session management policy joint modification process.
  • the SMF selects the UPF.
  • the UPF selected by the SMF is the second UPF.
  • the SMF initializes the session management policy joint modification process.
  • the SMF establishes an N4 session connection with the second UPF.
  • Step 1210 includes step 1210a and step 1210b.
  • Step 1210a is: the SMF sends an N4 session establishment/modification request to the second UPF.
  • Step 1210b is: the second UPF sends an N4 session establishment/modification response to the SMF.
  • the SMF requests the second UPF for the tunnel information of the second UPF (which may be recorded as the first tunnel information of the second UPF) for the second access network device to transmit the uplink data packet of the second PDU session,
  • the second UPF sends the first tunnel information of the second UPF to the SMF in step 1210b.
  • the SMF also requests the second UPF in step 1210a for the tunnel information of the second UPF (which can be recorded as the second tunnel of the second UPF for the second access network device to transmit the uplink data packet of the first PDU session). information), the second UPF sends the second tunnel information of the second UPF to the SMF in step 1210b.
  • the SMF also sends, in step 1210b, the tunnel information of the first UPF for establishing the forwarding tunnel between the second UPF and the first UPF to the second UPF (which may be recorded as the second tunnel information of the first UPF) , the second UPF sends the uplink data packet of the first PDU session to the first UPF through the forwarding tunnel.
  • the second tunnel information of the first UPF may be acquired by the SMF in step 1110b.
  • the SMF sends an N1N2 message to the AMF.
  • the N1N2 message further includes an N2 message, the N2 message includes first tunnel information of the second UPF, and optionally, further includes second tunnel information of the second UPF.
  • the N2 message may include first tunnel information of the second UPF and its corresponding second PDU session identifier, and second tunnel information of the second UPF and its corresponding first PDU session identifier, for indicating The first tunnel information of the second UPF of the second access network device is used to transmit the uplink data packets of the second PDU session, and the second tunnel information of the second UPF is used to transmit the uplink data packets of the first PDU session.
  • the N1N2 message further includes an N1 message, and the N1 message includes third indication information sent to the terminal, where the third indication information is used to instruct the terminal to send uplink data packets only on the first PDU session.
  • the SMF may determine to perform redundancy processing on the PDU session. For details, please refer to the relevant description of step 1111, which will not be repeated.
  • the AMF sends an N2 PDU session request to the first access network device.
  • the N2 PDU session request includes third indication information.
  • the N2 message in step 1211 is included in the N2 PDU session request.
  • the first access network device allocates radio resources.
  • step 1213 For the related description of step 1213, reference may be made to the above-mentioned step 1113, and details are not repeated here.
  • the first access network device sends an N2 PDU session response to the AMF.
  • step 1214 For the related description of step 1214, reference may be made to the above-mentioned step 1114, and details are not repeated here.
  • the AMF sends a PDU session update session context request of the second PDU session to the SMF.
  • the PDU session update session context request includes fourth indication information.
  • the PDU session update session context request further includes the tunnel information of the second access network device.
  • the first access network device may acquire the tunnel information of the second access network device by interacting with the second access network device.
  • the SMF executes the N4 session modification process.
  • the SMF sends the second indication information to the second UPF through the N4 session modification process, and the second indication information is used to instruct the second UPF to perform the application layer sequence number and GTP-U layer sequence number of the downlink data packet through the first mapping rule. mapping.
  • the SMF also sends the tunnel information of the second access network device and the N4 session identifier to the second UPF through the N4 session modification procedure, thereby establishing the downlink N3 link.
  • the second indication information is further used to indicate the first mapping rule.
  • step 1216 includes step 1216a and step 1216b.
  • Step 1216a is: the SMF sends an N4 session modification request to the second UPF, and the N4 session modification request may include second indication information.
  • Step 1216b is: the second UPF sends an N4 session modification response to the SMF.
  • the SMF sends a PDU session update session context response of the second PDU session to the AMF.
  • the first access network device sends the context of the second PDU session to the second access network device.
  • the context of the second PDU session includes the first tunnel information of the second UPF, so that the second access network device transmits the uplink data packet of the second PDU session to the second UPF.
  • the second tunnel information of the second UPF is further included, so that the second access network device transmits the uplink data packet of the first PDU session to the second UPF.
  • the first access network device will update the context of the second PDU session to the second access network device periodically or according to an event trigger, that is, when the first access network device discovers the context of the second PDU session When updating, the context of the second PDU session is updated to the second access network device.
  • Step 1218 can be executed after step 1213, and there is no strict execution order with other steps.
  • the second access network device When the second access network device detects that the first access network device is faulty, it starts to process the uplink data packet sent by the terminal through the first PDU session, and forwards it to the second UPF, and the second UPF forwards the uplink data packet to First UPF, the first UPF is sent to the DN.
  • the terminal also receives a downlink data packet sent by the DN through the second PDU session from the second UPF, and sends it to the terminal.
  • the SMF in addition to sending the third indication information to the terminal through steps 1211 to 1213, the SMF may also directly send the third indication information to the terminal through an N1 message.
  • the SMF may send the third indication information to the terminal in the first PDU session establishment process, or may send the third indication information to the terminal in the second PDU session establishment process, or In both PDU session establishment procedures, the third indication information is sent to the terminal, which is not limited in this application.
  • the first access network device may send the fourth indication information to the SMF in the first PDU session establishment process, may also send the fourth indication information to the SMF in the second PDU session establishment process, and may also send the fourth indication information to the SMF in the second PDU session establishment process. In every PDU session establishment process, the fourth indication information is sent to the SMF, which is not limited in this application.
  • the SMF may implement the foregoing solution 2 through the first PDU session establishment process and the second PDU session establishment process, which are exemplified by FIG. 13 and FIG. 14 , respectively.
  • the first PDU session establishment process includes:
  • 1301-1310 are the same as steps 1101 to 1110, respectively.
  • the SMF sends an N1N2 message to the AMF.
  • the N1N2 message includes an N2 message, and the N2 message includes first tunnel information of the first UPF, which is used by the first access network device to transmit the uplink data packet of the first PDU session to the first UPF, and also includes an indication of the first access network device.
  • the network access device processes the information of the first PDU session.
  • the N1N2 message further includes an N1 message
  • the N1 message includes fifth indication information sent to the terminal
  • the fifth indication information is used to indicate the second mapping rule of the terminal, so as to instruct the terminal to perform the same application layer according to the second mapping rule.
  • the SMF may determine to perform redundancy processing on the PDU session. For details, please refer to the relevant description of step 1111, which will not be repeated.
  • the AMF sends an N2 PDU session request to the first access network device.
  • the N2 PDU session request includes the N2 message in step 1311.
  • the N2 PDU session request includes fifth indication information.
  • the first access network device allocates radio resources.
  • the first access network device may perform an AN-specific resource setup (AN-specific resource setup) process. Radio resources are allocated through this process, and a PDU Session Establishment accept (PDU Session Establishment accept) message is sent to the terminal in this process.
  • AN-specific resource setup Radio resources are allocated through this process, and a PDU Session Establishment accept (PDU Session Establishment accept) message is sent to the terminal in this process.
  • PDU Session Establishment accept PDU Session Establishment accept
  • the first access network device sends fifth indication information to the terminal.
  • the second PDU session establishment process includes:
  • steps 1201 to 1209 are the same as steps 1201 to 1209 respectively.
  • Step 1410 includes step 1410a and step 1410b.
  • Step 1410a is: the SMF sends an N4 session establishment/modification request to the second UPF.
  • Step 1410b is: the second UPF sends an N4 session establishment/modification response to the SMF.
  • the SMF requests the second UPF in step 1410a for the first tunnel information of the second UPF for the second access network device to transmit the uplink data packet of the second PDU session, and the second UPF sends the second UPF in step 1410b the first tunnel information.
  • the SMF sends an N1N2 message to the AMF.
  • the N1N2 message includes an N2 message, and the N2 message includes first tunnel information of the second UPF, which is used to establish an uplink N3 link.
  • the N1N2 message further includes an N1 message, and the N1 message includes sixth indication information sent to the terminal, and the function of the sixth indication information may be the following function 1 or function 2.
  • the sixth indication information is used to instruct the terminal to associate the first PDCP entity with the second PDCP entity, wherein the first PDCP entity corresponds to the first PDU session, and the second PDCP entity corresponds to the second PDU session.
  • the terminal may generate the PDCP layer sequence number of the uplink data packet of the second PDU session according to the sixth indication information and the fifth indication information.
  • the sixth indication information is used to indicate the second mapping rule of the terminal, so as to instruct the terminal to perform mapping of the application layer sequence number and the PDCP layer sequence number of two uplink data packets of the same application layer data according to the second mapping rule.
  • the specific implementation can refer to the above, and details are not repeated here.
  • the SMF may determine to perform redundancy processing on the PDU session. For details, please refer to the relevant description of step 1111, which will not be repeated.
  • the AMF sends an N2 PDU session request to the first access network device.
  • the N2 PDU session request includes the N2 message in step 1411.
  • the N2 PDU session request may include sixth indication information.
  • the first access network device allocates radio resources.
  • the first access network device may perform an AN-specific resource setup (AN-specific resource setup) process. Radio resources are allocated through this process, and a PDU Session Establishment accept (PDU Session Establishment accept) message is sent to the terminal in this process.
  • AN-specific resource setup Radio resources are allocated through this process, and a PDU Session Establishment accept (PDU Session Establishment accept) message is sent to the terminal in this process.
  • PDU Session Establishment accept PDU Session Establishment accept
  • the first access network device sends sixth indication information to the terminal.
  • steps 1214 to 1217 are the same as steps 1214 to 1217, respectively.
  • the first access network device sends the context of the second PDU session to the second access network device.
  • the context of the second PDU session includes the first tunnel information of the second UPF, so that the second access network device transmits the uplink data packet of the second PDU session to the second UPF.
  • the first access network device will update the context of the second PDU session to the second access network device periodically or according to an event trigger, that is, when the first access network device discovers the context of the second PDU session When updating, the context of the second PDU session is updated to the second access network device.
  • Step 1418 can be executed after step 1413, and there is no strict execution order with other steps.
  • the second access network device When the second access network device detects the failure of the first access network device, it starts to process the uplink data packet sent by the terminal through the second PDU session, and forwards it to the second UPF, and the second UPF forwards the uplink data packet to DN.
  • the terminal also receives a downlink data packet sent by the DN through the second PDU session from the second UPF, and sends it to the terminal.
  • the terminal may associate the first PDCP entity corresponding to the first PDU session with the second PDCP entity corresponding to the second PDU session.
  • FIGS. 11-14 are optional steps.
  • the steps in FIG. 5-FIG. 8 and FIG. 10-FIG. 14 in this application may be more or less in actual implementation, and the sequence between each step may be other, and the figure only shows the steps between the steps. An example of the sequence of .
  • the application layer serial number is mapped to the GTP-U layer serial number, and then the GTP-U layer serial number is mapped to the PDCP layer serial number, so that when the first access network equipment fails, In this way, the smooth switching between the first access network device and the second access network device is realized.
  • the second access network device uses the second PDU session to transmit data, which implements fast switching between the first access network device and the second access network device, and reduces the first access network device. The switching delay between the network equipment and the second access network equipment is improved, and the reliability of data transmission is improved.
  • the SMF that manages the first UPF and the SMF that manages the second UPF are the same SMF.
  • the SMF that manages the first UPF and the SMF that manages the second UPF may also be different SMFs.
  • the SMF that directly or indirectly communicates with the first UPF is replaced by the SMF that manages the first UPF
  • the SMF that the second UPF communicates directly or indirectly may be replaced with the SMF that manages the second UPF.
  • each network element such as the SMF, the first UPF, the second UPF, the first access network device, the second access network device, the terminal, etc.
  • each network element includes executing the corresponding functions of each function.
  • the present application can be implemented in hardware or a combination of hardware and computer software with the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein. Whether a function is performed by hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Skilled artisans may implement the described functionality using different methods for each particular application, but such implementations should not be considered beyond the scope of this application.
  • the SMF, the first UPF, the second UPF, the first access network device, the second access network device, the terminal, etc. may be divided into functional units according to the foregoing method examples.
  • each function may be divided into each Functional unit, or two or more functions can be integrated into one processing unit.
  • the above-mentioned integrated units may be implemented in the form of hardware, or may be implemented in the form of software functional units. It should be noted that the division of units in the embodiments of the present application is illustrative, and is only a logical function division, and other division methods may be used in actual implementation.
  • FIG. 15 shows a possible schematic structural diagram of the communication device (referred to as the communication device 150 ) involved in the foregoing embodiment, where the communication device 150 includes a processing unit 1501 .
  • a communication unit 1502 and/or a storage unit 1503 are also included.
  • the schematic structural diagram shown in FIG. 15 may be used to illustrate the structures of the SMF, the first UPF, the second UPF, the first access network device, the second access network device, the terminal, and the like involved in the foregoing embodiment.
  • the processing unit 1501 is used to control and manage the actions of the SMF, for example, the processing unit 1501 is used to execute 501 and 502, each step in Fig. 6, 501, 502, 507b and 510 in Fig. 7, 803 and 804 in Fig. 8, 1103-1111 and 1115-1117 in Fig. 11, 1203-1211, 1215 in Fig. 12 - 1217 and 1219, 1303-1311 and 1315-1317 in Fig. 13, 1403-1411, 1415-1417 and 1419 in Fig. 14, and/or actions performed by the SMF in other processes described in the embodiments of this application .
  • the processing unit 1501 may communicate with other network entities through the communication unit 1502, for example, with the first UPF in FIG. 5 .
  • the storage unit 1503 is used to store program codes and data of the SMF.
  • the processing unit 1501 is used to control and manage the actions of the first UPF, for example, the processing unit 1501 is used to execute the operation of FIG. 5 501, 503 and 504 in Figure 6, 501 in Figure 6, 501, 503 and 504 in Figure 7, 803 and 805 in Figure 8, 1110a, 1110b, 1116a, 1116b in Figure 11, 1310a, 1310b, 1316a, 1316b, and/or actions performed by the first UPF in the other processes described in the embodiments of the present application.
  • the processing unit 1501 may communicate with other network entities through the communication unit 1502, eg, with the SMF shown in FIG. 5 .
  • the storage unit 1503 is used to store program codes and data of the first UPF.
  • the processing unit 1501 is used to control and manage the actions of the second UPF, for example, the processing unit 1501 is used to execute the operation of FIG. 5 502, 505 and 506 in FIG. 6, 502, 505 and 506 in FIG. 7, 801b, 802b, 802c, 804 and 805 in FIG. 8, 1003b, 1002b and 1002c in FIG. 1210a, 1210b, 1216a, 1216b, and 1219 in FIG. 14, 1410a, 1410b, 1416a, 1416b, and 1419 in FIG. 14, and/or actions performed by the second UPF in other processes described in the embodiments of the present application.
  • the processing unit 1501 may communicate with other network entities through the communication unit 1502, eg, with the SMF shown in FIG. 5 .
  • the storage unit 1503 is used to store program codes and data of the second UPF.
  • the processing unit 1501 is configured to control and manage the actions of the first access network device, for example, the processing unit 1501 is used to execute 504 in Fig. 5, 500a in Fig. 6, 504, 507a, 507b and 510 in Fig. 7, 1101 and 1112-1114 in Fig. 11, 1201, 1212-1214 and 1219 in Fig. 12, 1301 and 1312-1314 in FIG. 13, 1401, 1412-1414, and 1419 in FIG. 14, and/or actions performed by the first access network device in other processes described in the embodiments of this application.
  • the processing unit 1501 may communicate with other network entities through the communication unit 1502, eg, with the SMF shown in FIG. 5 .
  • the storage unit 1503 is used for storing program codes and data of the first access network device.
  • the processing unit 1501 is configured to control and manage the actions of the second access network device, for example, the processing unit 1501 is used to execute 506 in Fig. 5, 506 in Fig. 7, 801a, 801b, 801c, 802a, 802b, 802c and 802d in Fig. 8, each step in Fig. 10, 1218 and 1219 in Fig. 12, Fig. 1418 and 1419 in 14, and/or actions performed by the second access network device in other processes described in the embodiments of this application.
  • the processing unit 1501 may communicate with other network entities through the communication unit 1502, eg, with the SMF shown in FIG. 5 .
  • the storage unit 1503 is used for storing program codes and data of the second access network device.
  • the processing unit 1501 is used to control and manage the actions of the terminal.
  • the processing unit 1501 is used to execute 500b and 500c, 507a, 507b, 508 and 509 in Figure 7, 801a, 802a and 802d in Figure 8, 1001a, 1003a, 1002a and 1002d in Figure 10, 1101 and 1113 in Figure 11, 1201, 1213 and 1219, 1301 and 1313 in FIG. 13, 1401, 1413 and 1419 in FIG. 14, and/or actions performed by the terminal in other processes described in the embodiments of this application.
  • the processing unit 1501 may communicate with other network entities through the communication unit 1502, for example, communicate with the first access network device shown in FIG. 11 .
  • the storage unit 1503 is used to store program codes and data of the terminal.
  • FIG. 15 can also be used to illustrate the structure of other network elements (for example, AMF) involved in the present application.
  • AMF network management
  • each unit in FIG. 15 is used to perform the actions of the corresponding network element.
  • the communication device 150 may be a device or a chip in the device.
  • the processing unit 1501 may be a processor or a controller, and the communication unit 1502 may be a communication interface, a transceiver, a transceiver, a transceiver circuit, a transceiver device, and the like.
  • the communication interface is a general term, which may include one or more interfaces.
  • the storage unit 1503 may be a memory.
  • the processing unit 1501 may be a processor or a controller, and the communication unit 1502 may be an input interface and/or an output interface, a pin or a circuit, or the like.
  • the storage unit 1503 may be a storage unit (eg, a register, a cache, etc.) within the chip, or a storage unit (eg, a read-only memory, a random access memory, etc.) located outside the chip in the device.
  • the communication unit may also be referred to as a transceiver unit.
  • the antenna and control circuit with the transceiver function in the communication device 150 may be regarded as the communication unit 1502 of the communication device 150
  • the processor with the processing function may be regarded as the processing unit 1501 of the communication device 150 .
  • the device in the communication unit 1502 for implementing the receiving function may be regarded as a receiving unit, the receiving unit is used to perform the receiving steps in the embodiments of the present application, and the receiving unit may be a receiver, a receiver, a receiving circuit, or the like.
  • the device in the communication unit 1502 for implementing the sending function may be regarded as a sending unit, the sending unit is used to perform the sending steps in the embodiments of the present application, and the sending unit may be a transmitter, a transmitter, a sending circuit, or the like.
  • the medium includes several instructions to cause a computer device (which may be a personal computer, a server, or a network device, etc.) or a processor (processor) to execute all or part of the steps of the methods described in the various embodiments of the present application.
  • Storage media for storing computer software products include: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), magnetic disk or CD, etc. that can store program codes medium.
  • An embodiment of the present application further provides a schematic diagram of a hardware structure of a communication apparatus.
  • the communication apparatus includes a processor 1601 and, optionally, a memory 1602 connected to the processor 1601 .
  • the processor 1601 may be a general-purpose central processing unit (CPU), a microprocessor, an application-specific integrated circuit (ASIC), or one or more processors used to control the execution of the programs of the present application. integrated circuit.
  • the processor 1601 may also include multiple CPUs, and the processor 1601 may be a single-core (single-CPU) processor or a multi-core (multi-CPU) processor.
  • a processor herein may refer to one or more devices, circuits, or processing cores for processing data (eg, computer program instructions).
  • the memory 1602 can be a ROM or other type of static storage device that can store static information and instructions, a RAM or other type of dynamic storage device that can store information and instructions, or an electrically erasable programmable read-only memory.
  • read-only memory EEPROM
  • CD-ROM compact disc read-only memory
  • optical disc storage including compact disc, laser disc, optical disc, digital versatile disc, Blu-ray disc, etc.
  • magnetic disk A storage medium or other magnetic storage device, or any other medium that can be used to carry or store desired program codes in the form of instructions or data structures and that can be accessed by a computer, is not limited in this embodiment of the present application.
  • the memory 1602 may exist independently, and in this case, the memory 1602 may be located in the communication device, or may be located outside the communication device.
  • the memory 1602 may also be integrated with the processor 1601. Among them, the memory 1602 may contain computer program code.
  • the processor 1601 is configured to execute the computer program codes stored in the memory 1602, so as to implement the methods provided by the embodiments of the present application.
  • the communication device further includes a transceiver 1603 .
  • the processor 1601, the memory 1602 and the transceiver 1603 are connected by a bus.
  • the transceiver 1603 is used to communicate with other devices or communication networks.
  • the transceiver 1603 may include a transmitter and a receiver.
  • a device in the transceiver 1603 for implementing the receiving function may be regarded as a receiver, and the receiver is configured to perform the receiving steps in the embodiments of the present application.
  • the device in the transceiver 1603 for implementing the sending function may be regarded as a transmitter, and the transmitter is used to perform the sending step in the embodiment of the present application.
  • the schematic structural diagram shown in FIG. 16 may be used to illustrate the SMF, the first UPF, the second UPF, the first access network device, and the second access network device involved in the foregoing embodiment , terminals, etc.
  • the processor 1601 can be used to implement the functions of the processing unit 1501 in FIG. 15
  • the memory 1602 is used to implement the functions of the storage unit 1503 in FIG. 15
  • the transceiver 1603 is used to implement the functions of the communication unit 1502 in FIG. 15 .
  • the schematic structural diagram shown in FIG. 16 can also be used to illustrate the structure of other network elements (for example, AMF, etc.) involved in this application. In this case, each device in FIG. 16 is used to perform actions of the corresponding network elements.
  • AMF Access Mobility Management Function
  • the processor 1601 includes logic circuits, and an input interface and/or an output interface.
  • the output interface is used for executing the sending action in the corresponding method
  • the input interface is used for executing the receiving action in the corresponding method.
  • FIG. 17 The schematic structural diagram shown in FIG. 17 can be used to illustrate the SMF, the first UPF, the second UPF, the first access network device, the second UPF involved in the foregoing embodiment Structure of access network equipment, terminals, etc.
  • the processor 1601 is used to control and manage the actions of the SMF, for example, the processor 1601 is used to execute 501 and 502, each step in Fig. 6, 501, 502, 507b and 510 in Fig. 7, 803 and 804 in Fig. 8, 1103-1111 and 1115-1117 in Fig. 11, 1203-1211, 1215 in Fig. 12 - 1217 and 1219, 1303-1311 and 1315-1317 in Fig. 13, 1403-1411, 1415-1417 and 1419 in Fig. 14, and/or actions performed by the SMF in other processes described in the embodiments of this application .
  • the processor 1601 may communicate with other network entities, eg, with the first UPF in FIG. 5, through the input interface and/or the output interface.
  • Memory 1602 is used to store program codes and data for the SMF.
  • the processor 1601 is used to control and manage the actions of the first UPF, for example, the processor 1601 is used to execute the operation of FIG. 5 501, 503 and 504 in Figure 6, 501 in Figure 6, 501, 503 and 504 in Figure 7, 803 and 805 in Figure 8, 1110a, 1110b, 1116a, 1116b in Figure 11, 1310a, 1310b, 1316a, 1316b, and/or actions performed by the first UPF in the other processes described in the embodiments of the present application.
  • the processor 1601 may communicate with other network entities, eg, with the SMF shown in FIG. 5 , through the input interface and/or the output interface.
  • the memory 1602 is used to store program codes and data of the first UPF.
  • the processor 1601 is used to control and manage the actions of the second UPF, for example, the processor 1601 is used to execute the operation of FIG. 5 502, 505 and 506 in FIG. 6, 502, 505 and 506 in FIG. 7, 801b, 802b, 802c, 804 and 805 in FIG. 8, 1003b, 1002b and 1002c in FIG. 1210a, 1210b, 1216a, 1216b, and 1219 in FIG. 14, 1410a, 1410b, 1416a, 1416b, and 1419 in FIG. 14, and/or actions performed by the second UPF in other processes described in the embodiments of the present application.
  • the processor 1601 may communicate with other network entities, eg, with the SMF shown in FIG. 5 , through the input interface and/or the output interface.
  • the memory 1602 is used to store program codes and data of the second UPF.
  • the processor 1601 is configured to control and manage the actions of the first access network device, for example, the processor 1601 is used to execute 504 in Fig. 5, 500a in Fig. 6, 504, 507a, 507b and 510 in Fig. 7, 1101 and 1112-1114 in Fig. 11, 1201, 1212-1214 and 1219 in Fig. 12, 1301 and 1312-1314 in FIG. 13, 1401, 1412-1414, and 1419 in FIG. 14, and/or actions performed by the first access network device in other processes described in the embodiments of this application.
  • the processor 1601 may communicate with other network entities, eg, with the SMF shown in FIG. 5 , through the input interface and/or the output interface.
  • the memory 1602 is used to store program codes and data of the first access network device.
  • the processor 1601 is configured to control and manage the actions of the second access network device, for example, the processor 1601 is used to execute 506 in Fig. 5, 506 in Fig. 7, 801a, 801b, 801c, 802a, 802b, 802c and 802d in Fig. 8, various steps in Fig. 10, 1218 and 1219 in Fig. 12, Fig. 1418 and 1419 in 14, and/or actions performed by the second access network device in other processes described in the embodiments of this application.
  • the processor 1601 may communicate with other network entities, eg, with the SMF shown in FIG. 5 , through the input interface and/or the output interface.
  • the memory 1602 is used to store program codes and data of the second access network device.
  • the processor 1601 is used to control and manage the actions of the terminal.
  • the processor 1601 is used to execute 500b and 500c, 507a, 507b, 508 and 509 in Figure 7, 801a, 802a and 802d in Figure 8, 1001a, 1003a, 1002a and 1002d in Figure 10, 1101 and 1113 in Figure 11, 1201, 1213 and 1219, 1301 and 1313 in FIG. 13, 1401, 1413 and 1419 in FIG. 14, and/or actions performed by the terminal in other processes described in the embodiments of this application.
  • the processor 1601 may communicate with other network entities, eg, with the first access network device shown in FIG. 11 , through the input interface and/or the output interface.
  • the memory 1602 is used to store program codes and data of the terminal.
  • FIG. 17 can also be used to illustrate the structure of other network elements (for example, AMF, etc.) involved in the present application.
  • each device in FIG. 17 is used to perform the actions of the corresponding network elements.
  • please refer to The method part is understood and will not be repeated here.
  • Embodiments of the present application further provide a computer-readable storage medium, including instructions, which, when executed on a computer, cause the computer to execute any of the foregoing methods.
  • Embodiments of the present application also provide a computer program product containing instructions, which, when run on a computer, enables the computer to execute any of the above methods.
  • Embodiments of the present application further provide a communication device, including: a processor and an interface, where the processor is coupled to a memory through the interface, and when the processor executes a computer program in the memory or a computer-executed instruction, any of the above methods is executed.
  • a communication device including: a processor and an interface, where the processor is coupled to a memory through the interface, and when the processor executes a computer program in the memory or a computer-executed instruction, any of the above methods is executed.
  • the embodiments of the present application further provide a communication system, including: at least two network elements involved in the embodiments of the present application, for example, the above-mentioned SMF, a first UPF, a second UPF, a first access network device, and a second access network device.
  • a communication system including: at least two network elements involved in the embodiments of the present application, for example, the above-mentioned SMF, a first UPF, a second UPF, a first access network device, and a second access network device.
  • One or more of network devices and terminals are examples of network devices and terminals.
  • the above embodiments are described by taking the method provided in the present application applied in a 5G system as an example.
  • the above SMF can be replaced by a session management network element
  • the UPF can be replaced by a user plane network element
  • the DN can be replaced by a data network
  • other network elements can be replaced accordingly according to network element functions.
  • the computer program product includes one or more computer instructions.
  • the computer may be a general purpose computer, a special purpose computer, a computer network, or other programmable device.
  • Computer instructions may be stored in or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions may be transmitted from a website site, computer, server, or data center over a wire (e.g.
  • coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (eg infrared, wireless, microwave, etc.) means to transmit to another website site, computer, server or data center.
  • Computer-readable storage media can be any available media that can be accessed by a computer or data storage devices including one or more servers, data centers, etc., that can be integrated with the media.
  • Useful media may be magnetic media (eg, floppy disks, hard disks, magnetic tapes), optical media (eg, DVDs), or semiconductor media (eg, solid state disks (SSDs)), and the like.

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Abstract

本申请提供了一种通信方法及装置，涉及通信技术领域。该通信方法中，终端建立了锚定点为第一用户面网元的第一PDU会话和锚定点为第二用户面网元的第二PDU会话与数据网络通信，终端接入的接入网设备包括具有相同的小区配置的第一接入网设备和第二接入网设备，会话管理网元向第一用户面网元发送第一指示信息，向第二用户面网元发送第二指示信息，第一指示信息和第二指示信息均用于指示通过第一映射规则进行下行数据包的应用层序列号和GTP-U层序列号的映射，从而实现两个接入网设备的数据包处理的同步，保证业务通信不中断，达到提升通信链路可靠性的目的。

Description

通信方法及装置
本申请要求于2020年09月30日提交国家知识产权局、申请号为202011066410.8、申请名称为“通信方法及装置”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及通信技术领域，尤其涉及一种通信方法及装置。
背景技术
随着通信技术的发展，对于终端与其他设备(如终端或网络设备)之间的可靠性要求更高。例如，许多工业应用对于可靠性的要求基本上都在99.9999％以上，并且这些可靠性要求高的应用，基本上对于时延的要求也很高。而目前的通信架构往往不能满足一些通信场景中对于可靠性的要求。例如，在与工厂(to business，to B)相关业务的通信场景下，移动控制(motion control，MC)业务对于终端到其他设备的可靠性要求为999.999％，例如，一年中允许通信服务终端的故障总时长不超过30秒。而基于目前的通信架构进行该MC业务时，网络设备(例如，接入网设备)的可靠性仅为99.9％到99.99％，由此也导致整个通信链路的可靠性远不能满足MC业务等to B业务对于可靠性的要求。
为了解决业务对应的通信链路的可靠性无法满足业务的可靠性要求的问题，可以同时配置两个通信链路同步为单个业务提供通信服务，以便提升整体的可靠性。该情况下，一种通信架构可参见图1，可以包括终端、第一接入网设备、第二接入网设备、第一用户面功能(user plane function，UPF)以及第二UPF。其中，第一接入网设备和第二接入网设备具有相似(或相同)的小区覆盖能力。终端通过第一接入网设备，与核心网建立通信连接。例如，终端可以通过第一接入网设备与第一UPF进行数据或信令的交互。由此实现终端与第一UPF后端的数据网络(data network，DN)之间的业务通信。当第一接入网设备出现故障时，第二接入网设备可以代替第一接入网设备，与终端以及第二UPF进行通信，以便保证业务通信不中断，达到提升通信链路可靠性的目的。
在图1所示的通信架构中，第二接入网设备需要获知第一接入网设备处理到了哪个数据包，第二接入网设备才可以在第一接入网设备出现故障时代替第一接入网设备，但是目前对第二接入网设备如何获知第一接入网设备处理到了哪个数据包并没有解决方法，从而可能导致业务中断，无法达到提升通信链路可靠性的目的。
发明内容
本申请实施例提供了一种通信方法及装置，用于解决双UPF场景下两个接入网设备的数据包处理同步问题，从而保证业务通信不中断，达到提升通信链路可靠性的目的。
第一方面，提供了一种通信方法，包括：会话管理网元向第一用户面网元发送用于指示第一用户面网元通过第一映射规则进行下行数据包的应用层序列号和GTP-U层序列号的映射的第一指示信息，向第二用户面网元发送用于指示第二用户面网元通 过第一映射规则进行下行数据包的应用层序列号和GTP-U层序列号的映射的第二指示信息；其中，终端建立了第一PDU会话和第二PDU会话与数据网络通信，第一用户面网元和第二用户面网元分别为第一PDU会话和第二PDU会话的锚定点，终端接入的接入网设备包括第一接入网设备和第二接入网设备，第一接入网设备和第二接入网设备具有相同的小区配置；其中，在第一用户面网元接收到的第一下行数据包的应用层序列号与第二用户面网元接收到的第二下行数据包的应用层序列号相同的情况下，第一用户面网元向第一接入网设备发送的第一下行数据包的GTP-U层序列号与第二用户面网元向第二接入网设备发送的第二下行数据包的GTP-U层序列号相同。第一方面提供的通信方法，第一用户面网元和第二用户面网元可以采用相同的映射规则进行下行数据包的应用层序列号和GTP-U层序列号的映射，使得在第一用户面网元接收到的第一下行数据包的应用层序列号与第二用户面网元接收到的第二下行数据包的应用层序列号相同的情况下，第一用户面网元向第一接入网设备发送的第一下行数据包的GTP-U层序列号与第二用户面网元向第二接入网设备发送的第二下行数据包的GTP-U层序列号相同，实现两个接入网设备的数据包处理的同步(也就是实现两个接入网设备在用户面报文上的同步)，从而保证业务通信不中断，达到提升通信链路可靠性的目的。
在一种可能的实现方式中，第一指示信息和第二指示信息还用于指示第一映射规则。该种可能的实现方式，相比采用其他的指示信息指示第一映射规则，可以降低信令开销。
在一种可能的实现方式中，该方法还包括：会话管理网元向终端发送用于指示终端仅在第一PDU会话上发送上行数据包的第三指示信息。该种可能的实现方式，由于终端在第二PDU会话上不发送上行数据包，相比在两个PDU会话上都发送上行数据包而言，可以避免空口信号干扰，节省空口资源。
在一种可能的实现方式中，该方法还包括：会话管理网元指示第一接入网设备处理第一PDU会话。
在一种可能的实现方式中，该方法还包括：会话管理网元从第一用户面网元接收第一用户面网元的隧道信息，并向第二用户面网元发送第一用户面网元的隧道信息，用于第二用户面网元根据第一用户面网元的隧道信息转发第一PDU会话的上行数据包到第一用户面网元，其中，第一用户面网元的隧道信息包括第一用户面网元的隧道端点标识和IP地址。
在一种可能的实现方式中，在会话管理网元向第一用户面网元发送第一指示信息之前，该方法还包括：会话管理网元从第一接入网设备接收用于指示进行下行数据包的应用层序列号和GTP-U层序列号的映射的第四指示信息。
在一种可能的实现方式中，会话管理网元向第一用户面网元发送第一指示信息，包括：会话管理网元从终端接收用于请求建立第一PDU会话的第一PDU会话建立请求；在第一PDU会话建立请求中包括第二PDU会话的标识的情况下，会话管理网元向第一用户面网元发送第一指示信息。该种可能的实现方式，提供了一种发送第一指示信息的实现方式。
在一种可能的实现方式中，会话管理网元向第二用户面网元发送第二指示信息， 包括：会话管理网元从终端接收用于请求建立第二PDU会话的第二PDU会话建立请求；在第二PDU会话建立请求中包括第一PDU会话的标识的情况下，会话管理网元向第二用户面网元发送第二指示信息。该种可能的实现方式，提供了一种发送第二指示信息的实现方式。
第二方面，提供了一种通信方法，包括：第二用户面网元从会话管理网元接收第二指示信息，第二指示信息用于指示第二用户面网元通过第一映射规则进行下行数据包的应用层序列号和GTP-U层序列号的映射；其中，第二用户面网元为第二PDU会话的锚定点；在接收到第二PDU会话的第二下行数据包时，第二用户面网元根据第一映射规则进行第二下行数据包的应用层序列号和GTP-U层序列号的映射；第二用户面网元发送第二下行数据包。第二方面提供的通信方法，第二用户面网元可以采用第一映射规则进行下行数据包的应用层序列号和GTP-U层序列号的映射，在第一用户面网元也采用第一相同的映射规则进行下行数据包的应用层序列号和GTP-U层序列号的映射的情况下，可以实现两个接入网设备的数据包处理的同步，从而保证业务通信不中断，达到提升通信链路可靠性的目的。
在一种可能的实现方式中，第二指示信息还用于指示第一映射规则。该种可能的实现方式，相比采用其他的指示信息指示第一映射规则，可以降低信令开销。
在一种可能的实现方式中，该方法还包括：第二用户面网元从会话管理网元接收第一用户面网元的隧道信息，第一用户面网元的隧道信息包括第一用户面网元的隧道端点标识和IP地址，第一用户面网元为第一PDU会话的锚定点，第一PDU会话和第二PDU会话互为冗余会话；在接收到第一PDU会话的上行数据包时，第二用户面网元根据第一用户面网元的隧道信息向第一用户面网元发送第一PDU会话的上行数据包。
第三方面，提供了一种通信方法，包括：第一接入网设备确定启动备份传输时，向会话管理网元发送用于指示进行下行数据包的应用层序列号与GTP-U层序列号之间的映射的第四指示信息。
在一种可能的实现方式中，该方法还包括：第一接入网设备向终端发送用于指示终端仅在第一PDU会话上发送上行数据包的第三指示信息，终端建立了第一PDU会话和第二PDU会话与数据网络通信。该种可能的实现方式，由于终端在第二PDU会话上不发送上行数据包，相比在两个PDU会话上都发送上行数据包而言，可以避免空口信号干扰，节省空口资源。
在一种可能的实现方式中，该方法还包括：第一接入网设备丢弃终端通过第二PDU会话发送的上行数据包。该种可能的实现方式，可以释放第一接入网设备的存储空间，提高存储空间利用率。
第四方面，提供了一种通信方法，包括：在未检测到第一接入网设备故障的情况下，第二接入网设备接收终端通过第一PDU会话发送的第一上行数据包和第二用户面网元通过第二PDU会话发送的第三下行数据包，并缓存第一上行数据包和第三下行数据包；在检测到第一接入网设备故障的情况下，第二接入网设备接收终端通过第一PDU会话发送的第二上行数据包，并发送给第二用户面网元；第二接入网设备接收第二用户面网元通过第二PDU会话发送的第四下行数据包并发送给终端；其中，第一接入网 设备和第二接入网设备具有相同的小区配置，终端建立了第一PDU会话和第二PDU会话与数据网络通信，第一用户面网元和第二用户面网元分别为第一PDU会话和第二PDU会话的锚定点。第四方面提供的方法，在未检测到第一接入网设备故障的情况下，缓存第一上行数据包和第三下行数据包，可以在第一接入网设备故障的情况下，立即接管第一接入网设备，实现第一接入网设备和第二接入网设备的快速倒换。
第五方面，提供了一种通信方法，包括：在未检测到第一接入网设备故障的情况下，第二接入网设备接收终端通过第一PDU会话发送的第三上行数据包，并丢弃第三上行数据包；在检测到第一接入网设备故障的情况下，第二接入网设备接收终端通过第二PDU会话发送的第四上行数据包，并发送给第二用户面网元；第二接入网设备接收第二用户面网元通过第二PDU会话发送的第五下行数据包并发送给终端；其中，第一接入网设备和第二接入网设备具有相同的小区配置，终端通过第一PDU会话和第二PDU会话与数据网络通信，第一PDU会话和第二PDU会话的锚定点分别为第一用户面网元和第二用户面网元。第五方面提供的方法，在第一接入网设备故障的情况下，第二接入网设备使用第二PDU会话传输数据，实现第一接入网设备和第二接入网设备的快速倒换，降低了第一接入网设备和第二接入网设备倒换时延，提高了数据传输的可靠性。
在一种可能的实现方式中，该方法还包括：在未检测到第一接入网设备故障的情况下，第二接入网设备接收终端通过第二PDU会话发送的第五上行数据包和第二用户面网元通过第二PDU会话发送的第六下行数据包，并缓存第五上行数据包和第六下行数据包。该种可能的实现方式，在未检测到第一接入网设备故障的情况下，缓存第五上行数据包和第六下行数据包，可以在第一接入网设备故障的情况下，立即接管第一接入网设备，实现第一接入网设备和第二接入网设备的快速倒换。
第六方面，提供了一种通信方法，包括：终端从第一接入网设备或会话管理网元接收用于指示终端仅在第一PDU会话上发送上行数据包的第三指示信息，终端在第一PDU会话上发送上行数据包；其中，终端建立了第一PDU会话和第二PDU会话与数据网络通信，第一PDU会话和第二PDU会话互为冗余会话。第六方面提供的方法，由于终端在第二PDU会话上不发送上行数据包，相比在两个PDU会话上都发送上行数据包而言，可以避免空口信号干扰，节省空口资源。
在一种可能的实现方式中，该方法还包括：终端根据第三指示信息丢弃第二PDU会话上的上行数据包。
在一种可能的实现方式中，该方法还包括：终端向会话管理网元发送用于请求建立第一PDU会话的第一PDU会话建立请求，第一PDU会话建立请求中包括第二PDU会话的标识。
在一种可能的实现方式中，第二PDU会话的标识用于指示第二PDU会话和第一PDU会话互为冗余会话。该种可能的实现方式，可以使得会话管理网元确定第一PDU会话和第二PDU会话互为冗余会话。
在一种可能的实现方式中，该方法还包括：终端向会话管理网元发送用于请求建立第二PDU会话的第二PDU会话建立请求，第二PDU会话建立请求中包括第一PDU会话的标识。
在一种可能的实现方式中，第一PDU会话的标识用于指示第一PDU会话和第二PDU会话互为冗余会话。该种可能的实现方式，可以使得会话管理网元确定第一PDU会话和第二PDU会话互为冗余会话。
第七方面，提供了一种通信装置，包括：处理单元和通信单元；处理单元，用于通过通信单元向第一用户面网元发送第一指示信息，第一指示信息用于指示第一用户面网元通过第一映射规则进行下行数据包的应用层序列号和GTP-U层序列号的映射；处理单元，还用于通过通信单元向第二用户面网元发送第二指示信息，第二指示信息用于指示第二用户面网元通过第一映射规则进行下行数据包的应用层序列号和GTP-U层序列号的映射；其中，终端建立了第一PDU会话和第二PDU会话与数据网络通信，第一用户面网元和第二用户面网元分别为第一PDU会话和第二PDU会话的锚定点，终端接入的接入网设备包括第一接入网设备和第二接入网设备，第一接入网设备和第二接入网设备具有相同的小区配置；其中，在第一用户面网元接收到的第一下行数据包的应用层序列号与第二用户面网元接收到的第二下行数据包的应用层序列号相同的情况下，第一用户面网元向第一接入网设备发送的第一下行数据包的GTP-U层序列号与第二用户面网元向第二接入网设备发送的第二下行数据包的GTP-U层序列号相同。
在一种可能的实现方式中，第一指示信息和第二指示信息还用于指示第一映射规则。
在一种可能的实现方式中，处理单元，还用于通过通信单元向终端发送第三指示信息，第三指示信息用于指示终端仅在第一PDU会话上发送上行数据包。
在一种可能的实现方式中，处理单元，还用于通过通信单元指示第一接入网设备处理第一PDU会话。
在一种可能的实现方式中，处理单元，还用于通过通信单元从第一用户面网元接收第一用户面网元的隧道信息，第一用户面网元的隧道信息包括第一用户面网元的隧道端点标识和IP地址；处理单元，还用于通过通信单元向第二用户面网元发送第一用户面网元的隧道信息，用于第二用户面网元根据第一用户面网元的隧道信息转发第一PDU会话的上行数据包到第一用户面网元。
在一种可能的实现方式中，处理单元，还用于通过通信单元从第一接入网设备接收第四指示信息，第四指示信息用于指示进行下行数据包的应用层序列号和GTP-U层序列号的映射。
在一种可能的实现方式中，处理单元，还用于通过通信单元从终端接收第一PDU会话建立请求，第一PDU会话建立请求用于请求建立第一PDU会话；在第一PDU会话建立请求中包括第二PDU会话的标识的情况下，处理单元，具体用于通过通信单元向第一用户面网元发送第一指示信息。
在一种可能的实现方式中，处理单元，还用于通过通信单元从终端接收第二PDU会话建立请求，第二PDU会话建立请求用于请求建立第二PDU会话；在第二PDU会话建立请求中包括第一PDU会话的标识的情况下，处理单元，具体用于通过通信单元向第二用户面网元发送第二指示信息。
第八方面，提供了一种通信装置，包括：处理单元和通信单元；通信单元，用于从会话管理网元接收第二指示信息，第二指示信息用于指示通信装置通过第一映射规 则进行下行数据包的应用层序列号和GTP-U层序列号的映射；其中，通信装置为第二PDU会话的锚定点；在接收到第二PDU会话的第二下行数据包时，处理单元，用于根据第一映射规则进行第二下行数据包的应用层序列号和GTP-U层序列号的映射；通信单元，还用于发送第二下行数据包。
在一种可能的实现方式中，第二指示信息还用于指示第一映射规则。
在一种可能的实现方式中，通信单元，还用于从会话管理网元接收第一用户面网元的隧道信息，第一用户面网元的隧道信息包括第一用户面网元的隧道端点标识和IP地址，第一用户面网元为第一PDU会话的锚定点，第一PDU会话和第二PDU会话互为冗余会话；在接收到第一PDU会话的上行数据包时，通信单元，还用于根据第一用户面网元的隧道信息向第一用户面网元发送第一PDU会话的上行数据包。
第九方面，提供了一种通信装置，包括：处理单元和通信单元；在确定启动备份传输时，处理单元，用于通过通信单元向会话管理网元发送第四指示信息，第四指示信息用于指示进行下行数据包的应用层序列号与GTP-U层序列号之间的映射。
在一种可能的实现方式中，处理单元，还用于通过通信单元向终端发送第三指示信息，第三指示信息用于指示终端仅在第一PDU会话上发送上行数据包，终端建立了第一PDU会话和第二PDU会话与数据网络通信。
在一种可能的实现方式中，处理单元，还用于丢弃终端通过第二PDU会话发送的上行数据包。
第十方面，提供了一种通信装置，包括：处理单元和通信单元；在未检测到第一接入网设备故障的情况下，处理单元，用于通过通信单元接收终端通过第一PDU会话发送的第一上行数据包和第二用户面网元通过第二PDU会话发送的第三下行数据包，并缓存第一上行数据包和第三下行数据包；其中，第一接入网设备和通信装置具有相同的小区配置，终端建立了第一PDU会话和第二PDU会话与数据网络通信，第一用户面网元和第二用户面网元分别为第一PDU会话和第二PDU会话的锚定点；在检测到第一接入网设备故障的情况下，处理单元，还用于通过通信单元接收终端通过第一PDU会话发送的第二上行数据包，并发送给第二用户面网元；处理单元，还用于通过通信单元接收第二用户面网元通过第二PDU会话发送的第四下行数据包并发送给终端。
第十一方面，提供了一种通信装置，包括：处理单元和通信单元；在未检测到第一接入网设备故障的情况下，处理单元，用于通过通信单元接收终端通过第一PDU会话发送的第三上行数据包，并丢弃第三上行数据包；其中，第一接入网设备和通信装置具有相同的小区配置，终端通过第一PDU会话和第二PDU会话与数据网络通信，第一PDU会话和第二PDU会话的锚定点分别为第一用户面网元和第二用户面网元；在检测到第一接入网设备故障的情况下，处理单元，还用于通过通信单元接收终端通过第二PDU会话发送的第四上行数据包，并发送给第二用户面网元；处理单元，还用于通过通信单元接收第二用户面网元通过第二PDU会话发送的第五下行数据包并发送给终端。
在一种可能的实现方式中，在未检测到第一接入网设备故障的情况下，处理单元，还用于通过通信单元接收终端通过第二PDU会话发送的第五上行数据包和第二用户 面网元通过第二PDU会话发送的第六下行数据包，并缓存第五上行数据包和第六下行数据包。
第十二方面，提供了一种通信装置，包括：处理单元和通信单元；处理单元，用于通过通信单元从第一接入网设备或会话管理网元接收第三指示信息，第三指示信息用于指示通信装置仅在第一PDU会话上发送上行数据包，通信装置建立了第一PDU会话和第二PDU会话与数据网络通信，第一PDU会话和第二PDU会话互为冗余会话；处理单元，还用于通过通信单元在第一PDU会话上发送上行数据包。
在一种可能的实现方式中，处理单元，还用于根据第三指示信息丢弃第二PDU会话上的上行数据包。
在一种可能的实现方式中，处理单元，还用于通过通信单元向会话管理网元发送第一PDU会话建立请求，第一PDU会话建立请求用于请求建立第一PDU会话，第一PDU会话建立请求中包括第二PDU会话的标识。
在一种可能的实现方式中，第二PDU会话的标识用于指示第二PDU会话和第一PDU会话互为冗余会话。
在一种可能的实现方式中，处理单元，还用于通过通信单元向会话管理网元发送第二PDU会话建立请求，第二PDU会话建立请求用于请求建立第二PDU会话，第二PDU会话建立请求中包括第一PDU会话的标识。
在一种可能的实现方式中，第一PDU会话的标识用于指示第一PDU会话和第二PDU会话互为冗余会话。
第十三方面，提供了一种通信装置，包括：处理器。处理器与存储器连接，存储器用于存储计算机执行指令，处理器执行存储器存储的计算机执行指令，从而实现第一方面至第六方面中的任一方面提供的任意一种方法。示例性的，存储器和处理器可以集成在一起，也可以为独立的器件。若为后者，存储器可以位于通信装置内，也可以位于通信装置外。
在一种可能的实现方式中，处理器包括逻辑电路，还包括输入接口和/或输出接口。示例性的，输出接口用于执行相应方法中的发送的动作，输入接口用于执行相应方法中的接收的动作。
在一种可能的实现方式中，通信装置还包括通信接口和通信总线，处理器、存储器和通信接口通过通信总线连接。通信接口用于执行相应方法中的收发的动作。通信接口也可以称为收发器。可选的，通信接口包括发送器和接收器中的至少一种，该情况下，发送器用于执行相应方法中的发送的动作，接收器用于执行相应方法中的接收的动作。
在一种可能的实现方式中，通信装置以芯片的产品形态存在。
第十四方面，提供了一种通信装置，包括：处理器和接口，处理器通过接口与存储器耦合，当处理器执行存储器中的计算机程序或计算机执行指令时，使得第一方面至第六方面中的任一方面提供的任意一种方法被执行。
第十五方面，提供了一种计算机可读存储介质，包括计算机执行指令，当该计算机执行指令在计算机上运行时，使得计算机执行第一方面至第六方面中的任一方面提供的任意一种方法。
第十六方面，提供了一种计算机程序产品，包含计算机执行指令，当该计算机执行指令在计算机上运行时，使得计算机执行第一方面至第六方面中的任一方面提供的任意一种方法。
第十七方面，提供了一种通信系统，包括：上述各个方面提供的会话管理网元、第一用户面网元、第二用户面网元、第一接入网设备、第二接入网设备和终端中的一个或多个。
第七方面至第十七方面中的任一种实现方式所带来的技术效果可参见第一方面至第六方面中对应实现方式所带来的技术效果，此处不再赘述。
需要说明的是，在方案不矛盾的前提下，上述各个方面中的方案均可以结合。
附图说明
图1为一种终端和DN之间通信的示意图；
图2为一种网络架构组成示意图；
图3为一种PDU会话的示意图；
图4为本申请实施例提供的一种通信场景示意图；
图5为本申请实施例提供的一种通信方法的流程图；
图6为本申请实施例提供的又一种通信方法的流程图；
图7为本申请实施例提供的又一种通信方法的流程图；
图8为本申请实施例提供的又一种通信方法的流程图；
图9为本申请实施例提供的又一种通信场景示意图；
图10为本申请实施例提供的又一种通信方法的流程图；
图11为本申请实施例提供的又一种通信方法的流程图；
图12为本申请实施例提供的又一种通信方法的流程图；
图13为本申请实施例提供的又一种通信方法的流程图；
图14为本申请实施例提供的再一种通信方法的流程图；
图15为本申请实施例提供的一种通信装置的组成示意图；
图16为本申请实施例提供的一种通信装置的硬件结构示意图；
图17为本申请实施例提供的又一种通信装置的硬件结构示意图。
具体实施方式
在本申请的描述中，除非另有说明，“/”表示或的意思，例如，A/B可以表示A或B。本文中的“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。在本申请的描述中，除非另有说明，“至少一个”是指一个或多个，“多个”是指两个或多于两个。
另外，为了便于清楚描述本申请实施例的技术方案，在本申请的实施例中，采用了“第一”、“第二”等字样对功能和作用基本相同的相同项或相似项进行区分。本领域技术人员可以理解“第一”、“第二”等字样并不对数量和执行次序进行限定，并且“第一”、“第二”等字样也并不限定一定不同。
本申请实施例的技术方案可以应用于第四代(4th Generation，4G)系统、基于4G系统演进的各种系统、第五代(fifth generation，5G)系统、基于5G系统演进的各种 系统中。其中，4G系统也可以称为演进分组系统(evolved packet system，EPS)。4G系统的核心网(core network，CN)可以称为演进分组核心网(evolved packet core，EPC)，接入网可以称为长期演进(long term evolution，LTE)。5G系统的核心网可以称为5GC(5G core)，接入网可以称为新无线(new radio，NR)。为了方便描述，下文中以本申请应用于5G系统为例对本申请作示例性说明。在本申请应用于4G系统或其他的通信系统中时，将本申请涉及到的网元替换为相应通信系统中具有相同或相似功能的网元即可。
图2示例性的示出了5G系统的一种网络架构示意图。在该示意图中，5G系统可以包括：鉴权服务器功能(authentication server function，AUSF)网元、接入和移动性管理功能(access and mobility management function，AMF)网元、DN、统一数据管理(unified data management，UDM)网元、策略控制功能(policy control function，PCF)网元、(无线)接入网((radio)access network，(R)AN)网元、UPF网元、终端(terminal)、应用功能(application function，AF)网元、会话管理功能(session management function，SMF)网元。
为方便描述，在下文中将(R)AN网元、AMF网元、SMF网元、UDM网元、UPF网元、PCF网元等分别通过RAN、AMF、SMF、UDM、UPF、PCF等指代。
5G系统分为接入网和核心网两部分。接入网用于实现无线接入有关的功能，主要包括RAN。核心网用于网络业务的控制、数据的传输等，核心网由多个网元组成，主要包括：AMF、SMF、UPF、PCF、UDM等。
图2中部分网元的功能如下：
PCF，负责向AMF、SMF提供策略，如服务质量(quality of service，QoS)策略、切片选择策略等。
UDM，用于处理第三代合作伙伴计划(3rd generation partnership project，3GPP)认证和密钥协商(authentication and key agreement，AKA)认证凭据，用户识别处理，访问授权，注册/移动性管理，订购管理，短信管理等。
AF，可以是应用服务器，其可以属于运营商，也可以属于第三方。主要支持与3GPP核心网交互来提供服务，例如影响数据路由决策，策略控制功能或者向网络侧提供第三方的一些服务。
AMF，主要负责信令处理部分，例如，终端的注册管理、终端的连接管理、终端的可达性管理、终端的接入授权和接入鉴权、终端的安全功能，终端的移动性管理(如终端位置更新、终端注册网络、终端切换等)，网络切片(network slice)选择，SMF选择，终端的注册或去注册等功能。
SMF，主要负责终端会话管理的控制面功能，包括UPF的选择、控制以及重定向，网络互连协议(internet protocol，IP)地址分配及管理，会话的QoS管理，从PCF获取策略与计费控制(policy and charging control，PCC)策略，承载或会话的建立、修改以及释放等。
UPF，作为协议数据单元(protocol data unit，PDU)会话连接的锚定点，负责对终端的数据报文过滤、数据传输/转发、速率控制、生成计费信息、用户面QoS处理、上行传输认证、传输等级验证、下行数据包缓存及下行数据通知触发等。UPF还可以 作为多宿主(multi-homed)PDU会话的分支点。UPF中为终端提供服务的传输资源和调度功能由SMF进行管理控制。
RAN，由一个或多个接入网设备(也可以称为RAN节点或网络设备)组成的网络，实现无线物理层功能、资源调度和无线资源管理、无线接入控制以及移动性管理功能，服务质量管理，数据压缩和加密等功能。接入网设备通过用户面接口N3和UPF相连，用于传送终端的数据。接入网设备通过控制面接口N2和AMF建立控制面信令连接，用于实现无线接入承载控制等功能。
接入网设备，可以为基站、无线保真(wireless fidelity，WiFi)接入点(access point，AP)、全球微波接入互操作性(worldwide interoperability for microwave access，WiMAX)站点等。基站可以包括各种形式的基站，例如：宏基站，微基站(也称为小站)，中继站，接入点等。具体可以为：无线局域网(wireless local area network，WLAN)中的AP，全球移动通信系统(global system for mobile communications，GSM)或码分多址接入(code division multiple access，CDMA)中的基站(base transceiver station，BTS)，也可以是宽带码分多址(wideband code division multiple access，WCDMA)中的基站(NodeB，NB)，还可以是LTE中的演进型基站(evolved node B，eNB或eNodeB)，或者中继站或接入点，或者车载设备、可穿戴设备以及未来5G系统中的下一代节点B(the next generation node B，gNB)或者未来演进的公用陆地移动网(public land mobile network，PLMN)网络中的基站等。
终端可以是无线终端，或者，也可以是有线终端。无线终端可以是指向用户提供语音和/或数据连通性的设备，具有无线连接功能的手持式设备或连接到无线调制解调器的其他处理设备。终端与接入网设备之间采用某种空口技术(如NR技术或LTE技术)相互通信。终端与终端之间也可以采用某种空口技术(如NR技术或LTE技术)相互通信。无线终端可以经接入网设备与一个或多个核心网设备通信，如与AMF、SMF等进行通信。无线终端可以是移动终端(如移动电话)、智能电话、卫星无线设备、无线调制解调器卡、具有移动终端的计算机(例如，膝上型、便携式、袖珍式、手持式、计算机内置的或者车载的移动装置)、个人通信业务(personal communication service，PCS)电话、无绳电话、会话发起协议(session initiation protocol，SIP)话机、无线本地环路(wireless local loop，WLL)站、个人数字助理(personal digital assistant，PDA)、虚拟现实(virtual reality，VR)眼镜、增强现实(augmented reality，AR)眼镜、机器类型通信终端、物联网终端、路边单元(road side unit，RSU)、无人机上装载的通信设备等。无线终端也可以称为用户设备(user equipment，UE)、终端设备、订户单元(subscriber unit)、订户站(subscriber station)，移动站(mobile station)、移动台(mobile)、远程站(remote station)、接入点(access point)、接入终端(access terminal)、用户终端(user terminal)、用户代理(user agent)等。
DN指的是为用户提供数据传输服务的运营商网络，如网络互连协议多媒体业务(IP multi-media service，IMS)网络、互联网(Internet)等。终端通过建立终端到接入网设备到UPF到DN之间的PDU会话(PDU session)，访问DN。PDU会话是终端和DN之间的连接，用于提供PDU连接服务。其中，PDU会话类型可以是IP连接、以太网连接或者非结构数据连接等。5G系统的核心网支持的PDU连接服务，是指提 供终端和由数据网络名称(data network name，DNN)确定的DN之间PDU交换的服务。终端可以发起建立一个或多个PDU会话，来连接到相同的DN或者不同的DN。例如，图3中，终端发起建立PDU会话1和PDU会话2，来连接到相同的DN。
可以理解的是，除图2所示功能网元之外，5G网络的网络架构还可以包括其他功能网元。例如，网络开放功能(network exposure function，NEF)等，在本申请实施例中，网元也可以称为实体或设备等。
基于图1所示的通信架构，终端可以建立两个PDU会话，分别为第一PDU会话和第二PDU会话，第一PDU会话的锚定点为第一UPF(也就是说，第一PDU会话的数据包需要经过第一UPF)，第二PDU会话的锚定点为第二UPF(也就是说，第二PDU会话的数据包需要经过第二UPF)。其中，数据包也可以称为业务报文。
本申请实施例中，作为一种可能的实现方式，第二接入网设备可以作为第一接入网设备的备份站，以便当第一接入网设备出现故障时，第二接入网设备可以保证业务通信不中断，由此提升整个通信链路的可靠性。
在不同实现场景下，第一接入网设备和第二接入网设备可以有相同的频率部署，也可以有不同的频率部署。第一接入网设备和第二接入网设备可以全带宽备份，也可以频谱部分共享。例如，以频谱带宽为100兆赫兹(MHz)为例。第一接入网设备可以使用前50MHz工作，后50MHz对第二接入网设备进行备份。类似的，第二接入网设备可以使用前50MHz对第一接入网设备进行备份，后50MHz对其他终端提供服务。在不同的实现场景下，第一接入网设备和第二接入网设备的标识可以相同，也可以不同。
第二接入网设备可以从第一接入网设备获取第一接入网设备的小区配置参数。第二接入网设备可以根据第一接入网设备的小区配置参数进行小区配置，从而实现相同小区配置和覆盖，以便当第一接入网设备出现故障时，第二接入网设备能够无延迟无丢包地实现对终端的业务通信的切换。此时，对于终端而言，只可以看到一个逻辑的接入网设备，并不会区分第一接入网设备和第二接入网设备。由于第二接入网设备和第一接入网设备有相同小区配置和覆盖，因此，终端通过第一PDU会话发送的上行数据包，第一接入网设备和第二接入网设备都可以接收到，终端通过第二PDU会话发送的上行数据包，第一接入网设备和第二接入网设备也都可以接收到。针对同一应用层数据，DN会生成两个下行数据包，并通过第一PDU会话和第二PDU会话分别发送给第一UPF和第二UPF，这两个下行数据包的应用层序列号相同。第一接入网设备和第二接入网设备的隧道信息不同，第一UPF根据第一接入网设备的隧道信息发送第一PDU会话的下行数据包给第一接入网设备，第二UPF根据第二接入网设备的隧道信息发送第二PDU会话的下行数据包给第二接入网设备。
第二接入网设备还可以与AMF以及UPF预先建立数据传输通道，以便当第一接入网设备出现故障时，第二接入网设备能够无延迟无掉包地实现对核心网设备的业务通信的切换。由此即可保证在第一接入网设备出现故障时，第二接入网设备能够快速准确地接管相关业务，保证业务通信的高质量传输，以达到提升通信链路可靠性的目的。
第一接入网设备还可以通过与第二接入网设备之间的交互，实现第一接入网设备 与第二接入网设备之间的同步配置，以便在第一接入网设备出现故障时，第二接入网设备可以顺利地接管第一接入网设备的相关业务，保证业务通信的顺利进行。其中，同步配置可以包括以下信息的一种或多种的配置：第一PDU会话的上下文，第二PDU会话的上下文，处理第一PDU会话的接入网设备的信息，处理第二PDU会话的接入网设备的信息，接入层(access stratum，AS)上下文，核心网上下文，移动性管理(mobility management，MM)上下文，AS秘钥，非接入层(non-access-stratum，NAS)秘钥，以及对应的安全算法等信息中的至少一项，还可以包括无线资源控制(radio resource control，RRC)信息，以及层2(layer 2，L2)信息等中的至少一项。其中，PDU会话的上下文可以包括PDU会话中不同的业务流或QoS流已经传输的报文的序列号，或者即将传输的报文的系列号，具体的序列号可以是分组数据汇聚协议(packet data convergence protocol，PDCP)层的序列号。
为了解决背景技术中提出的问题，基于图1所示的通信架构，本申请提供了两种方案(记为方案1和方案2)，以下分别进行描述。
方案1
在方案1中，终端仅通过第一PDU会话发送上行数据包。DN(具体可以为DN中的业务服务器)通过第一PDU会话和第二PDU会话发送下行数据包。针对接收到的应用层序列号相同的下行数据包，第一UPF和第二UPF采用相同的映射规则进行下行数据包的应用层序列号(sequence number，SN)和通用分组无线服务隧道协议用户面(general packet radio service tunneling protocol user plane，GTP-U)层序列号的映射，从而保证针对DN发送的应用层序列号相同的下行数据包，第一接入网设备接收到的下行数据包和第二接入网设备接收到的下行数据包的GTP-U层序列号相同，实现两个接入网设备的数据包处理的同步，从而保证业务通信不中断，达到提升通信链路可靠性的目的。
在方案1中，图4中的(a)示出了第一接入网设备在未发生故障时的通信路径。参见图4中的(a)中的路径1，终端通过第一PDU会话发送上行数据包之后，第一接入网设备将接收到的该上行数据包发送给第一UPF，第一UPF再发送给DN。DN通过第一PDU会话发送下行数据包之后，第一UPF将接收到的该下行数据包发送给第一接入网设备，第一接入网设备发送给终端。参见图4中的(a)中的路径2，终端通过第一PDU会话发送上行数据包之后，第二接入网设备接收该上行数据包。此时，由于第一接入网设备会通过第一UPF将第一PDU会话的上行数据包发送至DN，因此，第二接入网设备可以不向第二UPF转发第一PDU会话的上行数据包。参见图4中的(a)中的路径3，DN通过第二PDU会话发送下行数据包之后，第二UPF将下行数据包发送给第二接入网设备。此时，由于第一接入网设备会将接收到的第一PDU会话的下行数据包发送给终端，因此，第二接入网设备可以不向终端发送接收到第二PDU会话的下行数据包。
在方案1中，图4中的(b)示出了第一接入网设备在发生故障时的通信路径。参见图4中的(b)中的路径1，由于第一接入网设备发生故障，因此，路径1无法再用于传输数据。此时，针对下行数据包，参见图4中的(b)中的路径2，DN通过第二PDU会话发送下行数据包之后，第二UPF将接收到的该下行数据包发送给第二接入网 设备，第二接入网设备发送给终端。针对上行数据包，参见图4中的(b)中的路径3，终端通过第一PDU会话发送上行数据包之后，第二接入网设备接收该上行数据包，并发送给第二UPF，由于第一PDU会话的锚定点为第一UPF，因此，第二UPF将该上行数据包发送给第一UPF，第一UPF再发送给DN。
具体的，参见图5，方案1提供的通信方法包括：
501、SMF向第一UPF发送第一指示信息，第一指示信息用于指示第一UPF通过第一映射规则进行下行数据包的应用层序列号和GTP-U层序列号的映射。相应的，第一UPF从SMF接收第一指示信息。
其中，终端建立了第一PDU会话和第二PDU会话与DN通信，终端接入的接入网设备包括第一接入网设备和第二接入网设备，第一接入网设备和第二接入网设备具有相同的小区配置。由于第一接入网设备和第二接入网设备具有相同的小区配置，因此，第一PDU会话和第二PDU会话互为冗余会话。其中，冗余会话是指传输相同的上行应用层数据和下行应用层数据的会话。
其中，第一UPF为第一PDU会话的锚定点。
其中，下行数据包的应用层所采用的协议可以为应用层冗余协议。应用层冗余协议可以为高可用性无缝冗余协议(high-availability seamless redundancy，HSR)、并行冗余协议(parallel redundancy protocol，PRP)和帧冗余复制和去重(frame replication and elimination for reliability，FRER)等。
GTP-U层是指用于接入网设备与UPF之间进行隧道传输的协议层，在不同的通信系统的协议栈架构中，具体该功能的协议层还可以有其他的名称，本申请不作限制。
可选的，第一指示信息还用于指示第一映射规则。第一映射规则也可以为预设的或通过其他指示信息指示的，本申请不作限制。
作为一种实现方式，第一映射规则可以是将GTP-U层序列号设置成接收到的下行数据包的应用层序列号，比如，应用层序列号为00000000 00010001，则GTP-U层序列号也设置成00000000 00010001。
作为另一种实现方式，第一映射规则可以是将应用层序列号作为输入参数，代入预设的函数，确定该应用层序列号对应的GTP-U层序列号。
作为另一种实现方式，第一映射规则可以是将应用层序列号和服务质量流标识(quality of service flow indicator，QFI)作为输入参数，代入预设的函数，确定该应用层序列号对应的GTP-U层序列号。其中，QFI是下行数据包所在的QoS流的标识。
502、SMF向第二UPF发送第二指示信息，第二指示信息用于指示第二UPF通过第一映射规则进行下行数据包的应用层序列号和GTP-U层序列号的映射。相应的，第二UPF从SMF接收第二指示信息。
其中，第二UPF为第二PDU会话的锚定点。
可选的，第二指示信息还用于指示第一映射规则。第一映射规则也可以为预设的或通过其他指示信息指示的，本申请不作限制。
503、在接收到第一PDU会话的第一下行数据包(即DN通过第一PDU会话发送的第一下行数据包)时，第一UPF根据第一映射规则进行第一下行数据包的应用层序列号和GTP-U层序列号的映射。
504、第一UPF向第一接入网设备发送第一下行数据包。
505、在接收到第二PDU会话的第二下行数据包(即DN通过第二PDU会话发送的第二下行数据包)时，第二UPF根据第一映射规则进行第二下行数据包的应用层序列号和GTP-U层序列号的映射。
506、第二UPF向第二接入网设备发送第二下行数据包。
其中，在第一UPF接收到的第一下行数据包的应用层序列号与第二UPF接收到的第二下行数据包的应用层序列号相同的情况下，第一UPF向第一接入网设备发送的第一下行数据包的GTP-U层序列号与第二UPF向第二接入网设备发送的第二下行数据包的GTP-U层序列号相同。
在后续过程中，第一接入网设备和/或第二接入网设备需要发送下行数据包时，根据下行数据包的GTP-U层序列号映射为PDCP层序列号后发送给终端。
具体的，第一接入网设备和/或第二接入网设备根据下行数据包的GTP-U层序列号映射为PDCP层序列号的方法可以是：
方法一、第一接入网设备和/或第二接入网设备将GTP-U层的序列号作为输入参数，代入预设的函数，确定PDCP层的序列号。
方法二、第一接入网设备和/或第二接入网设备将GTP-U层的序列号和QFI作为输入参数，代入预设的函数，确定PDCP层的序列号。
方案1提供的通信方法，第一UPF和第二UPF可以采用相同的映射规则进行下行数据包的应用层序列号和GTP-U层序列号的映射，使得在第一UPF接收到的第一下行数据包的应用层序列号与第二UPF接收到的第二下行数据包的应用层序列号相同的情况下，第一UPF向第一接入网设备发送的第一下行数据包的GTP-U层序列号与第二UPF向第二接入网设备发送的第二下行数据包的GTP-U层序列号相同，实现两个接入网设备的数据包处理的同步(也就是实现两个接入网设备在用户面报文上的同步)，从而保证业务通信不中断，达到提升通信链路可靠性的目的。
在方案1中，SMF可以在满足以下条件1至条件3中的任意一个或多个条件时，执行步骤501和/或步骤502。
条件1、SMF从第一接入网设备接收第四指示信息。其中，第四指示信息用于指示以下信息中的任意一种或多种：
信息1、进行下行数据包的应用层序列号和GTP-U层序列号的映射。
信息2、第一接入网设备支持双连接，即网络中有与该第一接入设备匹配的第二接入网设备，第二接入网设备和第一接入网设备具有相同的小区配置。
信息3、第一接入网设备确定启动备份传输，即第一接入网设备确定启动第二接入网设备执行备份传输，第二接入网设备和第一接入网设备具有相同的小区配置。
在条件1中，可选的，第一接入网设备确定启动备份传输时，通过AMF向SMF发送第四指示信息。备份传输的目的是为了实现数据传输的高可靠性。其中，第一接入网设备可以默认启动备份传输，也可以在获取到第一PDU会话或第二PDU会话对应的S-NSSAI和/或DNN、且S-NSSAI和/或DNN设置为需要启动备份传输时，确定启动备份传输。其中，S-NSSAI和/或DNN可以是第一PDU会话或第二PDU会话建立或修改的过程中，AMF发送给第一接入网设备的。例如，S-NSSAI和/或DNN可以 携带在N2 PDU会话请求(N2 PDU Session Request)中。需要启动备份传输的S-NSSAI和/或DNN可以是预设的。
条件2、SMF从终端接收第一PDU会话建立请求，第一PDU会话建立请求用于请求建立第一PDU会话，并且第一PDU会话建立请求中包括第二PDU会话的标识。
在条件2中，终端向SMF发送第一PDU会话建立请求。
在条件2中，第二PDU会话的标识用于指示第二PDU会话和第一PDU会话互为冗余会话。用于指示第二PDU会话和第一PDU会话互为冗余会话的信息还可以为第一PDU会话建立请求中的其他信息，本申请不作限制。
条件3、SMF从终端接收第二PDU会话建立请求，第二PDU会话建立请求用于请求建立第二PDU会话，并且第二PDU会话建立请求中包括第一PDU会话的标识。
在条件3中，终端向SMF发送第二PDU会话建立请求。
在条件3中，第一PDU会话的标识用于指示第一PDU会话和第二PDU会话互为冗余会话。用于指示第一PDU会话和第二PDU会话互为冗余会话的信息还可以为第二PDU会话建立请求中的其他信息，本申请不作限制。
在满足以上条件1至条件3中的任意一个或多个条件时，说明需要对上行数据包或下行数据包进行可靠性保障，因此，SMF可以步骤501和/或步骤502。示例性的，参见图6，在步骤500a(对应条件1)、500b(对应条件2)、500c(对应条件3)中的任意一个或多个步骤被执行时，SMF可以步骤501和/或步骤502。具体的，SMF可以在满足条件1或条件2或条件3的情况下，执行步骤501和步骤502，也可以在满足条件2的情况下，执行步骤501，在满足条件3的情况下，执行步骤502。
在方案1中，可选的，参见图7，该方法还包括：
507、SMF或第一接入网设备向终端发送第三指示信息，第三指示信息用于指示终端仅在第一PDU会话上发送上行数据包。相应的，终端从第一接入网设备或通过第一接入网设备从SMF接收第三指示信息。步骤507包括步骤507a或步骤507b。步骤507a是指第一接入网设备向终端发送第三指示信息，终端从第一接入网设备接收第三指示信息。步骤507b是指SMF通过第一接入网设备向终端发送第三指示信息，终端通过第一接入网设备从SMF接收第三指示信息。
508、终端在第一PDU会话上发送上行数据包。具体的，终端可以根据第三指示信息仅在第一PDU会话上发送上行数据包。
在方案1中，可选的，参见图7，该方法还包括：
509、终端根据第三指示信息丢弃第二PDU会话上的上行数据包；或者，终端根据第三指示信息不生成第二PDU会话上的上行数据包。具体的，终端可以在第二PDU会话对应的PDCP层生成上行数据包后丢弃，或者，终端可以不在第二PDU会话对应的PDCP层生成上行数据包。
在方案1中，可选的，参见图7，该方法还包括：
510、SMF指示第一接入网设备处理第一PDU会话。相应的，第一接入网设备根据该指示处理第一PDU会话。具体的，针对上行数据包，第一接入网设备接收终端通过第一PDU会话发送的上行数据包，并发送给第一UPF，第一UPF发送给DN。针对下行数据包，DN通过第一PDU会话发送下行数据包给第一UPF，第一UPF发送给第 一接入网设备，第一接入网设备发送给终端。
可选的，参见图8，该方法还包括：
801、在未检测到第一接入网设备故障的情况下，第二接入网设备接收终端通过第一PDU会话发送的第一上行数据包和第二UPF通过第二PDU会话发送的第三下行数据包，并缓存第一上行数据包和第三下行数据包。
步骤801包括步骤801a、步骤801b和步骤801c。步骤801a为：终端通过第一PDU会话发送第一上行数据包，第二接入网设备接收第一上行数据包。步骤801b为：第二UPF通过第二PDU会话向第二接入网设备发送第三下行数据包，第二接入网设备接收第三下行数据包。步骤801c为：第二接入网设备缓存第一上行数据包和第三下行数据包。
802、在检测到第一接入网设备故障的情况下，第二接入网设备接收终端通过第一PDU会话发送的第二上行数据包，并发送给第二UPF；第二接入网设备接收第二UPF通过第二PDU会话发送的第四下行数据包并发送给终端。
步骤802包括步骤802a、步骤802b、步骤802c和802d。步骤802a为：终端通过第一PDU会话发送第二上行数据包，第二接入网设备接收第二上行数据包。步骤802b为：第二接入网设备向第二UPF发送第二上行数据包，第二UPF接收第二上行数据包。步骤802c为：第二UPF通过第二PDU会话向第二接入网设备发送第四下行数据包，第二接入网设备接收第四下行数据包。步骤802d为：第二接入网设备向终端发送第四下行数据包。
具体的，在第二接入网设备将第一PDU会话的上行数据包发送给第二UPF之前，第二接入网设备根据从第一接入网设备获取的第一PDU会话的上下文，确定需要发送给第二UPF的上行数据包。示例性的，第二接入网设备从第一PDU会话的上下文中获取第一接入网设备发送给第一UPF的第一PDU会话的第一QoS流的最后一个上行数据包的PDCP层序列号x，第二接入网设备确定要向第二UPF发送第一PDU会话的第一QoS流的上行数据包的PDCP序列号为x+1，将该数据包封装为GTP-U数据包后发给第二UPF。
需要说明的是，在未检测到第一接入网设备故障的情况下，第一接入网设备会处理终端通过第一PDU会话发送的上行数据包和第一UPF通过第一PDU会话发送的下行数据包，此时，不需要第二接入网设备处理上行数据包或下行数据包，因此，第二接入网设备可以缓存上行数据包或下行数据包，在缓存时间达到一定的时间后丢弃上行数据包或下行数据包。具体的，可以设置一个缓存定时器(timer)，该定时器超时时，丢弃该上行数据包或下行数据包。
可选的，参见图8，该方法还包括：
803、SMF从第一UPF接收第一UPF的隧道信息，该隧道信息包括第一UPF的隧道端点标识和IP地址。
804、SMF向第二UPF发送第一UPF的隧道信息，并配置路由规则，用于第二UPF根据该隧道信息和路由规则转发第一PDU会话的上行数据包到第一UPF。相应的，第二UPF从SMF接收第一UPF的隧道信息和路由规则。可选的，该路由规则包括第一PDU会话的上行数据包所关联的业务的描述信息，例如，可以是IP五元组。第二 UPF接收到上行数据包后，若与路由规则中的业务描述信息相匹配，则根据该第一UPF的隧道信息向第一UPF转发该上行数据包。
805、在接收到第一PDU会话的上行数据包时，第二UPF根据第一UPF的隧道信息向第一UPF发送第一PDU会话的上行数据包。
需要说明的是，在检测到第一接入网设备故障的情况下，第二接入网设备接收终端通过第一PDU会话发送的上行数据包，并发送给第二UPF，由于第一PDU会话的锚定点为第一UPF，因此，第二UPF需要通过第二UPF和第一UPF之间的隧道向第一UPF发送第一PDU会话的上行数据包，第一UPF再向DN发送该第一PDU会话的上行数据包。因此，第二UPF需要获知第一UPF的隧道信息，以便通过第一UPF的隧道信息对应的隧道发送第一PDU会话的上行数据包给第一UPF。可选的，第二接入网设备向第二UPF发送第一PDU会话的上行数据包，可以是通过第二接入网设备与第二UPF之间的针对第一PDU会话的隧道来发送，也就是说第二接入网设备和第二UPF之间传输第一PDU会话和第二PDU会话所用的隧道可以不同。
方案2
在方案2中，终端通过第一PDU会话和第二PDU会话发送上行数据包。DN(具体可以为DN中的业务服务器)通过第一PDU会话和第二PDU会话发送下行数据包。针对接收到的应用层序列号相同的下行数据包，第一UPF和第二UPF采用相同的映射规则进行下行数据包的应用层序列号和GTP-U层序列号的映射，从而保证针对DN发送的应用层序列号相同的下行数据包，第一接入网设备接收到的下行数据包和第二接入网设备接收到的下行数据包的GTP-U层序列号相同，实现两个接入网设备的数据包处理的同步，从而保证业务通信不中断，达到提升通信链路可靠性的目的。
在方案2中，图9中的(a)示出了第一接入网设备在未发生故障时的通信路径。参见图9中的(a)中的路径1，终端通过第一PDU会话发送上行数据包之后，第一接入网设备将接收到的该上行数据包发送给第一UPF，第一UPF再发送给DN。DN通过第一PDU会话发送下行数据包之后，第一UPF将接收到的该下行数据包发送给第一接入网设备，第一接入网设备发送给终端。参见图9中的(a)中的路径2，终端通过第二PDU会话发送上行数据包之后，第一接入网设备将接收到的该上行数据包丢弃。参见图9中的(a)中的路径3，终端通过第一PDU会话发送上行数据包之后，第二接入网设备接收该上行数据包。参见图9中的(a)中的路径4，终端通过第二PDU会话发送上行数据包之后，第二接入网设备接收该上行数据包，并进行缓存。由于第二接入网设备会缓存第二PDU会话的上行数据包，因此，第一PDU会话的上行数据包第二接入网设备可以丢弃。参见图9中的(a)中的路径5，DN通过第二PDU会话发送下行数据包之后，第二UPF将下行数据包发送给第二接入网设备。此时，由于第一接入网设备会将接收到的第一PDU会话的下行数据包发送给终端，因此，第二接入网设备可以不向终端发送接收到第二PDU会话的下行数据包。
在方案2中，图9中的(b)示出了第一接入网设备在发生故障时的通信路径。参见图9中的(b)中的路径1和路径2，由于第一接入网设备发生故障，因此，路径1和路径2无法再用于传输数据。此时，参见图9中的(b)中的路径3，DN通过第二PDU会话发送下行数据包之后，第二UPF将接收到的该下行数据包发送给第二接入网 设备，第二接入网设备发送给终端。终端通过第二PDU会话发送上行数据包之后，第二接入网设备接收该上行数据包，并发送给第二UPF，第二UPF再发送给DN。参见图9中的(b)中的路径4，终端通过第一PDU会话发送上行数据包之后，第二接入网设备接收该上行数据包，由于第二接入网设备转发第二PDU会话的上行数据包，因此，第一PDU会话的上行数据包第二接入网设备可以丢弃。
在方案2中，各个网元执行的大部分动作与方案1中相同，因此，为了避免冗余，该部分仅仅描述方案2和方案1中的不同点，其余部分可参照方案1进行理解。
不同点1、由于在方案2中，终端通过第一PDU会话和第二PDU会话发送上行数据包，因此，方案1中的步骤507和步骤508不执行。相应的，与第三指示信息相关的动作也不需执行。
不同点2、由于在方案2中，第一接入网设备在发生故障时，第二接入网设备处理终端通过第二PDU会话发送的上行数据包和DN通过第二PDU会话发送的下行数据包。此时，第二UPF接收第二接入网设备发送的第二PDU会话的上行数据包，不需要处理第一PDU会话的上行数据包。因此，步骤803至步骤805不执行。
不同点3、由于第一接入网设备可以接收到第二PDU会话的上行数据包，但是第一接入网设备不处理第二PDU会话的上行数据包，因此，第一接入网设备可以执行以下动作：第一接入网设备丢弃终端通过第二PDU会话发送的上行数据包。
不同点4、由于终端执行的动作不同，在方案2中，针对第二接入网设备，上述步骤801和步骤802不执行，参见图10，可以执行以下步骤1001和步骤1002：
1001、在未检测到第一接入网设备故障的情况下，第二接入网设备接收终端通过第一PDU会话发送的第三上行数据包，并丢弃第三上行数据包。
步骤1001包括步骤1001a和步骤1001b。步骤1001a为：终端通过第一PDU会话发送第三上行数据包，第二接入网设备接收终端通过第一PDU会话发送的第三上行数据包。步骤1001b为：第二接入网设备丢弃第三上行数据包。
1002、在检测到第一接入网设备故障的情况下，第二接入网设备接收终端通过第二PDU会话发送的第四上行数据包，并发送给第二UPF；第二接入网设备接收第二UPF通过第二PDU会话发送的第五下行数据包并发送给终端。
步骤1002包括步骤1002a、步骤1002b、步骤1002c和1002d。步骤1002a为：终端通过第二PDU会话发送第四上行数据包，第二接入网设备接收终端通过第二PDU会话发送的第四上行数据包。步骤1002b为：第二接入网设备向第二UPF发送第四上行数据包，第二UPF接收第四上行数据包。步骤1002c为：第二UPF通过第二PDU会话向第二接入网设备发送第五下行数据包，第二接入网设备接收第五下行数据包。步骤1002d为：第二接入网设备向终端发送第五下行数据包。
需要说明的是，由于第二接入网设备主要处理第二PDU会话的上行数据包或下行数据包，而此时终端也会通过第二PDU会话发送上行数据包，因此，在第二接入网设备接收到第三上行数据包时，第二接入网设备可以丢弃第三上行数据包。
在方案2中，参见图10，该方法还包括：在未检测到第一接入网设备故障的情况下，第二接入网设备接收终端通过第二PDU会话发送的第五上行数据包和第二UPF通过第二PDU会话发送的第六下行数据包，并缓存第五上行数据包和第六下行数据包。
步骤1003包括步骤1003a、步骤1003b和步骤1003c。步骤1003a为：终端通过第二PDU会话发送第五上行数据包，第二接入网设备接收终端通过第二PDU会话发送的第五上行数据包。步骤1003b为：第二UPF通过第二PDU会话发送第六下行数据包，第二接入网设备接收第二UPF通过第二PDU会话发送的第六下行数据包。步骤1003c为：第二接入网设备缓存第五上行数据包和第六下行数据包。
需要说明的是，由于第二接入网设备主要处理第二PDU会话的上行数据包或下行数据包，第二接入网设备在接收到第二PDU会话的上行数据包或下行数据包后，可以缓存该上行数据包或下行数据包，并在缓存时间达到一定的时间后丢弃上行数据包或下行数据包。
在方案2中，终端将第一PDCP实体和第二PDCP实体关联。其中，第一PDCP实体与第一PDU会话对应，第二PDCP实体与第二PDU会话对应。关联的两个PDCP实体为携带同一业务流的同一应用层数据的两个上行数据包分配相同的PDCP层序列号，终端在第一PDU会话和第二PDU会话上发送这两个上行数据包。具体的，针对同一业务流的同一应用层数据的两个上行数据包，终端可以均按照第二映射规则根据应用层序列号生成PDCP层序列号，以保证同一业务流的同一应用层数据的两个上行数据包分配相同的PDCP层序列号。具体的，终端根据应用层序列号映射PDCP层序列号的方法可以是：
方法一、终端将应用层序列号作为输入参数，代入预设的函数，确定PDCP层序列号。
方法二、终端将应用层序列号和QFI作为输入参数，代入预设的函数，确定PDCP层序列号。
第二映射规则可以是预配置在终端上，也可以是SMF通过第一接入网设备和/或第二接入网设备在会话建立过程中下发给终端的。
上述方案1相比方案2而言，由于终端在第二PDU会话上不发送上行数据包，因此，可以避免空口信号干扰，节省空口资源。
在上述方案1和方案2中，第二接入网设备可以通过以下方式1至方式3中的任意一种或多种方式确定第一接入网设备是否故障。
方式1、第二接入网设备接收来自终端的信息，并根据终端反馈的信息，确定第一接入网设备是否出现故障。
例如，该信息可以为终端反馈的肯定确认(Acknowledgement，ACK)/否定确认(Negative-Acknowledgment，NACK)。应当理解的是，大部分终端相关业务均为周期性业务，终端会根据与其保持通信的接入网设备(如第一接入网设备)发送的信息进行ACK/NACK反馈。由于第二接入网设备处于能够接收信息的状态，因此第二接入网设备能够接收到与第一接入网设备保持通信的多个终端上报的ACK/NACK的情况。当第二接入网设备在某个周期接收到的NACK占比超过第一阈值(如80％)时，则第二接入网设备确定第一接入网设备出现故障。
方式2、第二接入网设备接收来自终端的测量信息，并根据测量信息确定第一接入网设备是否出现故障。
例如，第一接入网设备发送第一参考信息，该第一参考信息可以为信道状态指示 参考信号(channel status indication reference signal，CSI-RS)，信道状态指示干扰测量(CSI-interference measurement，CSI-IM)，解调参考信号(demodulation reference signal，DMRS)，小区参考信号(cell reference signal，CRS)中的一个或多个。终端接收第一接入网设备发送的第一参考信息，并进行测量，测量后可以根据第一接入网设备的配置进行周期性或者基于事件进行上报。第二接入网设备和第一接入网设备是同频同配置因此可以接收到终端上报的测量结果，第二接入网设备根据终端上报的测量值，若低于某一阈值，则判断第一接入网设备出现故障。第二接入网设备可以根据至少一个终端的上报结果进行判定。具体的终端若是根据事件触发上报，则可以设置第二阈值，当测量结果低于该值时进行上报。则第二接入网设备可根据至少一个终端上报结果进行判断第一接入网设备故障。例如，以第一参考信息为CSI-RS为例。第二接入网设备接收到来自终端1和终端2反馈的CSI-RS测量结果小于第二阈值时，则认为终端和第一接入网设备之间的通信出现问题，即第一接入网设备出现故障。
方式3、第二接入网设备接收来自第一接入网设备的第二参考信息，并根据该第二参考信息，确定第一接入网设备是否出现故障。
示例性的，类似于上述说明，第二接入网设备可以对第二参考信号进行测量，若测量结果低于第三阈值，则确定第一接入网设备出现故障。所述第二参考信息与第一参考信息可以相同。第二接入网设备可以根据第一接入网设备发送的对第二参考信息的配置进行测量。
在第二接入网设备确定第一接入网设备出现故障后，就可以接管第一接入网设备与终端之间的通信。当第一UPF确定第一接入网设备数据不可达后，则停止向第一接入网设备传输数据。待到第一接入网设备故障解除恢复工作后，第一UPF即可向第一接入网设备发送数据，恢复双路传输。第一接入网设备与第二接入网设备互为备份关系，且故障恢复后可以维持当前工作状态或者转换为第一接入网设备工作第二接入网设备备份的状态，需要第一接入网设备和第二接入网设备协商，比如可以协商一个时间点第一接入网设备接管第二接入网设备停止工作，也可以第一接入网设备向第二接入网设备发送接管指示，第二接入网设备停止工作，第一接入网设备继续工作。
为了使得本申请上述实施例更加的清楚，以下通过实施例1和实施例2对上述方案1和方案2的实现流程作示例性说明。
实施例1
实施例1中，SMF可以通过第一PDU会话建立流程和第二PDU会话建立流程实现上述方案1，以下通过图11和图12分别进行示例性说明。
参见图11，第一PDU会话建立流程包括：
1101、终端向AMF发送第一PDU会话建立请求(PDU Session Establishment Request)。
其中，第一PDU会话建立请求用于请求建立第一PDU会话。第一PDU会话建立请求除了包括第一PDU会话的标识外，还包括第二PDU会话的标识，从而指示第二PDU会话和第一PDU会话互为冗余会话。
其中，第二PDU会话的标识可以为终端提前为第二PDU会话分配的。
1102、AMF进行SMF选择(SMF selection)。
1103、AMF向SMF发送第一PDU会话的PDU会话创建会话上下文请求(Nsmf_PDU Session_CreateSMContext Request)。
其中，第一PDU会话的PDU会话创建会话上下文请求用于请求创建第一PDU会话的上下文。该请求中包括步骤1101中终端发送的第一PDU会话的标识以及第二PDU会话的标识，从而指示第二PDU会话和第一PDU会话互为冗余会话。
1104、若SMF中没有终端的签约信息，SMF通过订阅检索(Subscription retrieval)/订阅更新(Subscription for updates)流程从UDM获取终端的签约信息。
1105、SMF向AMF发送第一PDU会话的PDU会话创建会话上下文的响应(Nsmf_PDU Session_CreateSMContext Response)。
1106、各个网元交互进行第一PDU会话的鉴权与授权(PDU Session authentication/authorization)流程。
1107、若第一PDU会话采用动态策略控制和计费(Policy Control and Charging，PCC)，SMF执行PCF选择，并初始化会话管理策略联合建立(SM Policy Association Establishment)/会话管理策略联合修改(SM Policy Association Modification)流程。
步骤1107包括图11中的步骤1107a和步骤1107b。步骤1107a为：SMF进行PCF选择。步骤1107b为：SMF初始化会话管理策略联合建立/会话管理策略联合修改流程。
1108、SMF进行UPF选择(UPF selection)。
其中，SMF选择出的UPF即第一UPF。
1109、SMF初始化会话管理策略联合修改流程。
1110、SMF与第一UPF建立N4会话连接。
步骤1110包括步骤1110a和步骤1110b。步骤1110a为：SMF向第一UPF发送N4会话建立/修改请求(N4 Session Establishment/Modification Request)。步骤1110b为：第一UPF向SMF发送N4会话建立/修改响应(N4 Session Establishment/Modification Response)。
其中，SMF在步骤1110a中向第一UPF请求用于第一接入网设备传输第一PDU会话的上行数据包的第一UPF的隧道信息(可以记为第一UPF的第一隧道信息)，第一UPF在步骤1110b中发送第一UPF的第一隧道信息给SMF。
1111、SMF向AMF发送N1N2消息(Namf_Communication__N1N2MessageTransfer)。
其中，N1N2消息中包括N2消息，N2消息中包括第一UPF的第一隧道信息，用于建立上行N3链路，还包括指示第一接入网设备处理第一PDU会话的信息。可选的，SMF可以向第一接入网设备指示第一PDU会话为主PDU会话，第一接入网设备接收到SMF的指示后，处理第一PDU会话。或者SMF可以向第一接入网设备发送第七指示信息，第一接入网设备接收到该第七指示信息后，处理第一PDU会话。
其中，N1N2消息中还包括N1消息，可选的，N1消息中包括发送给终端的第三指示信息，第三指示信息用于指示所述终端仅在所述第一PDU会话上发送上行数据包。
在步骤1111之前，SMF可以确定对PDU会话做冗余处理。具体的，SMF可以根据在步骤1103获取的第一PDU会话和第二PDU会话互为冗余会话的信息确定对第一PDU会话和第二PDU会话做冗余处理。或者，SMF也可以根据第一PDU会话对应的 DNN或S-NSSAI确定是否对PDU会话做冗余处理。具体的，若SMF接收到的第一PDU会话的PDU会话创建会话上下文请求中包括的第一PDU会话对应的DNN或S-NSSAI为需要进行备份传输的DNN或S-NSSAI时，确定对PDU会话做冗余处理。
进一步的，SMF可以在第一接入网设备具备进行备份传输的能力的情况下，确定对PDU会话做冗余处理。
其中，DNN或S-NSSAI、第一PDU会话和第二PDU会话互为冗余会话的信息(例如，第一PDU会话和第二PDU会话的标识)、第一接入网设备是否具备进行备份传输的能力等信息可以携带在步骤1103的PDU会话创建会话上下文请求中携带给SMF。
其中，第一接入网设备是否具备进行备份传输的能力的信息可以在NG Setup(NG连接建立)过程中AMF从第一接入网设备获取。
1112、AMF向第一接入网设备发送N2 PDU会话请求(N2_PDUSession_Request)。
其中，N2 PDU会话请求中包括步骤1111中的N2消息，可选的，还包括第三指示信息。
1113、第一接入网设备分配无线资源。
具体的，第一接入网设备可以执行AN-特定资源建立(AN-specific resource setup)流程。通过该流程分配无线资源，并在该流程中将PDU会话建立接受(PDU Session Establishment accept)消息发送给终端。
其中，在分配无线资源的过程中，第一接入网设备将第三指示信息发送给终端。
1114、第一接入网设备向AMF发送N2 PDU会话响应(N2 PDU Session Response)。
其中，N2 PDU会话响应中包括第四指示信息，第四指示信息用于指示进行下行数据包的应用层序列号和GTP-U层序列号的映射。N2 PDU会话响应中还包括第一接入网设备的隧道信息。
在步骤1114之前，第一接入网设备可以确定启动备份传输。具体的，第一接入网设备可以默认启动备份传输，也可以是在步骤1112中接收到的N2 PDU会话请求中包括第一PDU会话对应的DNN或S-NSSAI、且该DNN或S-NSSAI为需要进行备份传输的DNN或S-NSSAI时，确定启动备份传输。
1115、AMF向SMF发送第一PDU会话的PDU会话更新会话上下文请求(Nsmf_PDU Session_UpdateSMContext Request)。
其中，PDU会话更新会话上下文请求中包括第四指示信息。PDU会话更新会话上下文请求中还包括第一接入网设备的隧道信息。
1116、SMF执行N4会话修改流程。
其中，SMF通过N4会话修改流程将第一指示信息发送给第一UPF，第一指示信息用于指示第一UPF通过第一映射规则进行下行数据包的应用层序列号和GTP-U层序列号的映射。SMF还通过N4会话修改流程将第一接入网设备的隧道信息和N4会话标识发送给第一UPF，从而建立下行N3链路。
可选的，第一指示信息还用于指示第一映射规则。
其中，步骤1116包括步骤1116a和步骤1116b。步骤1116a为：SMF向第一UPF发送N4会话修改请求(N4 Session Modification Request)，N4会话修改请求中可以包括第一指示信息。步骤1116b为：第一UPF向SMF发送N4会话修改响应(N4 Session  Modification Response)。
1117、SMF向AMF发送第一PDU会话的PDU会话更新会话上下文响应(Nsmf_PDU Session_UpdateSMContext Response)。
参见图12，第二PDU会话建立流程包括：
1201、终端向AMF发送第二PDU会话建立请求。
其中，第二PDU会话建立请求用于请求建立第二PDU会话。第二PDU会话建立请求中除了包括第二PDU会话的标识外，还包括第一PDU会话的标识，从而指示第一PDU会话和第二PDU会话互为冗余会话。
1202、AMF进行SMF选择。
1203、AMF向SMF发送第二PDU会话的PDU会话创建会话上下文请求。
其中，第二PDU会话的PDU会话创建会话上下文请求用于请求创建第二PDU会话的上下文。可选的，该请求中包括步骤1201中终端发送的第一PDU会话的标识以及第二PDU会话的标识，从而指示第二PDU会话和第一PDU会话互为冗余会话。
1204、若SMF中没有终端的签约信息，SMF通过订阅检索/订阅更新流程从UDM获取终端的签约信息。
1205、SMF向AMF发送第二PDU会话的PDU会话创建会话上下文的响应。
1206、各个网元交互进行第二PDU会话的鉴权与授权。
1207、若第二PDU会话采用动态策略控制和计费，SMF执行PCF选择，并初始化会话管理策略联合建立/会话管理策略联合修改流程。
步骤1207包括图12中的步骤1207a和步骤1207b。步骤1207a为：SMF进行PCF选择。步骤1207b为：SMF初始化会话管理策略联合建立/会话管理策略联合修改流程。
1208、SMF进行UPF选择。
其中，SMF选择出的UPF即第二UPF。
1209、SMF初始化会话管理策略联合修改流程。
1210、SMF与第二UPF建立N4会话连接。
步骤1210包括步骤1210a和步骤1210b。步骤1210a为：SMF向第二UPF发送N4会话建立/修改请求。步骤1210b为：第二UPF向SMF发送N4会话建立/修改响应。
其中，SMF在步骤1210a中向第二UPF请求用于第二接入网设备传输第二PDU会话的上行数据包的第二UPF的隧道信息(可以记为第二UPF的第一隧道信息)，第二UPF在步骤1210b中发送第二UPF的第一隧道信息给SMF。
可选的，SMF还在步骤1210a中向第二UPF请求用于第二接入网设备传输第一PDU会话的上行数据包的第二UPF的隧道信息(可以记为第二UPF的第二隧道信息)，第二UPF在步骤1210b中发送第二UPF的第二隧道信息给SMF。
可选的，SMF还在步骤1210b中向第二UPF发送用于建立第二UPF和第一UPF之间的转发隧道的第一UPF的隧道信息(可以记为第一UPF的第二隧道信息)，第二UPF通过该转发隧道将第一PDU会话的上行数据包发送给第一UPF。具体的，第一UPF的第二隧道信息可以是SMF在步骤1110b中获取的。
1211、SMF向AMF发送N1N2消息。
其中，N1N2消息中还包括N2消息，N2消息中包括第二UPF的第一隧道信息， 可选的，还包括第二UPF的第二隧道信息。作为另一种实施方式，N2消息可以包括第二UPF的第一隧道信息以及其对应的第二PDU会话标识，第二UPF的第二隧道信息以及其对应的第一PDU会话标识，用于指示第二接入网设备第二UPF的第一隧道信息用于传输第二PDU会话的上行数据包，第二UPF的第二隧道信息用于传输第一PDU会话的上行数据包。
其中，N1N2消息中还包括N1消息，N1消息中包括发送给终端的第三指示信息，第三指示信息用于指示所述终端仅在所述第一PDU会话上发送上行数据包。
在步骤1211之前，SMF可以确定对PDU会话做冗余处理，具体可参见步骤1111的相关描述，不再赘述。
1212、AMF向第一接入网设备发送N2 PDU会话请求。
其中，N2 PDU会话请求中包括第三指示信息。N2 PDU会话请求中包括步骤1211中的N2消息。
1213、第一接入网设备分配无线资源。
步骤1213的相关描述可参见上述步骤1113，不再赘述。
1214、第一接入网设备向AMF发送N2 PDU会话响应。
步骤1214的相关描述可参见上述步骤1114，不再赘述。
1215、AMF向SMF发送第二PDU会话的PDU会话更新会话上下文请求。
其中，PDU会话更新会话上下文请求中包括第四指示信息。PDU会话更新会话上下文请求中还包括第二接入网设备的隧道信息。第一接入网设备可以通过和第二接入网设备交互获取第二接入网设备的隧道信息。
1216、SMF执行N4会话修改流程。
其中，SMF通过N4会话修改流程将第二指示信息发送给第二UPF，第二指示信息用于指示第二UPF通过第一映射规则进行下行数据包的应用层序列号和GTP-U层序列号的映射。SMF还通过N4会话修改流程将第二接入网设备的隧道信息和N4会话标识发送给第二UPF，从而建立下行N3链路。
可选的，第二指示信息还用于指示第一映射规则。
其中，步骤1216包括步骤1216a和步骤1216b。步骤1216a为：SMF向第二UPF发送N4会话修改请求，N4会话修改请求中可以包括第二指示信息。步骤1216b为：第二UPF向SMF发送N4会话修改响应。
1217、SMF向AMF发送第二PDU会话的PDU会话更新会话上下文响应。
1218、第一接入网设备向第二接入网设备发送第二PDU会话的上下文。
其中，第二PDU会话的上下文中包括第二UPF的第一隧道信息，以便第二接入网设备传输第二PDU会话的上行数据包给第二UPF。可选的，还包括第二UPF的第二隧道信息，以便第二接入网设备传输第一PDU会话的上行数据包给第二UPF。
需要说明的是，第一接入网设备会周期性的或者根据事件触发，向第二接入网设备更新第二PDU会话的上下文，即当第一接入网设备发现第二PDU会话的上下文更新时，向第二接入网设备更新第二PDU会话的上下文。
步骤1218在步骤1213之后执行即可，与其他步骤没有严格的执行顺序。
1219、当第二接入网设备检测到第一接入网设备故障时，开始处理终端通过第一 PDU会话发送的上行数据包，并转发到第二UPF，第二UPF将上行数据包转发给第一UPF，第一UPF发送给DN。终端还从第二UPF接收DN通过第二PDU会话发送的下行数据包，并发送给终端。
在实施例1所示的方案中，SMF除了通过步骤1211至步骤1213向终端发送第三指示信息之外，也可以直接通过N1消息发送第三指示信息给终端。
在实施例1所示的方案中，SMF可以在第一PDU会话建立流程中将第三指示信息发送给终端，也可以在第二PDU会话建立流程中将第三指示信息发送给终端，还可以在两个PDU会话建立流程中都发送第三指示信息给终端，本申请不作限制。类似的，第一接入网设备可以在第一PDU会话建立流程中将第四指示信息发送给SMF，也可以在第二PDU会话建立流程中将第四指示信息发送给SMF，还可以在两个PDU会话建立流程中都发送第四指示信息给SMF，本申请不作限制。
实施例2
实施例2中，SMF可以通过第一PDU会话建立流程和第二PDU会话建立流程实现上述方案2，以下通过图13和图14分别进行示例性说明。
参见图13，第一PDU会话建立流程包括：
1301-1310、与步骤1101至步骤1110分别相同。
1311、SMF向AMF发送N1N2消息。
其中，N1N2消息中包括N2消息，N2消息中包括第一UPF的第一隧道信息，用于第一接入网设备传输第一PDU会话的上行数据包给第一UPF，还包括指示第一接入网设备处理第一PDU会话的信息。
可选的，N1N2消息中还包括N1消息，N1消息中包括发送给终端的第五指示信息，第五指示信息用于指示终端第二映射规则，以指示终端根据第二映射规则进行同一应用层数据的两个上行数据包的应用层序列号和PDCP层序列号的映射。具体实现可参见上文，不再赘述。
在步骤1311之前，SMF可以确定对PDU会话做冗余处理，具体可参见步骤1111的相关描述，不再赘述。
1312、AMF向第一接入网设备发送N2 PDU会话请求。
其中，N2 PDU会话请求中包括步骤1311中的N2消息。
可选的，N2 PDU会话请求中包括第五指示信息。
1313、第一接入网设备分配无线资源。
具体的，第一接入网设备可以执行AN-特定资源建立(AN-specific resource setup)流程。通过该流程分配无线资源，并在该流程中将PDU会话建立接受(PDU Session Establishment accept)消息发送给终端。
可选的，在分配无线资源的过程中，第一接入网设备将第五指示信息发送给终端。
1314-1317、与步骤1114至步骤1117分别相同。
参见图14，第二PDU会话建立流程包括：
1401-1409、与步骤1201至步骤1209分别相同。
1410、步骤1410包括步骤1410a和步骤1410b。步骤1410a为：SMF向第二UPF 发送N4会话建立/修改请求。步骤1410b为：第二UPF向SMF发送N4会话建立/修改响应。
其中，SMF在步骤1410a中向第二UPF请求用于第二接入网设备传输第二PDU会话的上行数据包的第二UPF的第一隧道信息，第二UPF在步骤1410b中发送第二UPF的第一隧道信息。
1411、SMF向AMF发送N1N2消息。
其中，N1N2消息包括N2消息，N2消息中包括第二UPF的第一隧道信息，用于建立上行N3链路。
其中，N1N2消息还包括N1消息，N1消息中包括发送给终端的第六指示信息，第六指示信息的作用可以为以下作用1或作用2。
作用1、第六指示信息用于指示终端将第一PDCP实体和第二PDCP实体关联，其中，第一PDCP实体与第一PDU会话对应，第二PDCP实体与第二PDU会话对应。终端可以根据第六指示信息以及第五指示信息，生成第二PDU会话的上行数据包的PDCP层序列号。
作用2、第六指示信息用于指示终端第二映射规则，以指示终端根据第二映射规则进行同一应用层数据的两个上行数据包的应用层序列号和PDCP层序列号的映射。具体实现可参见上文，不再赘述。
在步骤1411之前，SMF可以确定对PDU会话做冗余处理，具体可参见步骤1111的相关描述，不再赘述。
1412、AMF向第一接入网设备发送N2 PDU会话请求。
其中，N2 PDU会话请求中包括步骤1411中的N2消息。其中，N2 PDU会话请求中可以包括第六指示信息。
1413、第一接入网设备分配无线资源。
具体的，第一接入网设备可以执行AN-特定资源建立(AN-specific resource setup)流程。通过该流程分配无线资源，并在该流程中将PDU会话建立接受(PDU Session Establishment accept)消息发送给终端。
可选的，在分配无线资源的过程中，第一接入网设备将第六指示信息发送给终端。
1414-1417、与步骤1214至步骤1217分别相同。
1418、第一接入网设备向第二接入网设备发送第二PDU会话的上下文。
其中，第二PDU会话的上下文中包括第二UPF的第一隧道信息，以便第二接入网设备传输第二PDU会话的上行数据包给第二UPF。
需要说明的是，第一接入网设备会周期性的或者根据事件触发，向第二接入网设备更新第二PDU会话的上下文，即当第一接入网设备发现第二PDU会话的上下文更新时，向第二接入网设备更新第二PDU会话的上下文。
步骤1418在步骤1413之后执行即可，与其他步骤没有严格的执行顺序。
1419、当第二接入网设备检测到第一接入网设备故障时，开始处理终端通过第二PDU会话发送的上行数据包，并转发到第二UPF，第二UPF将上行数据包转发给DN。终端还从第二UPF接收DN通过第二PDU会话发送的下行数据包，并发送给终端。
在实施例2中，在建立第一PDU会话和第二PDU会话之后，终端可以将与第一PDU会话对应的第一PDCP实体和与第二PDU会话对应的第二PDCP实体关联。
上述图11-图14中的虚线步骤为可选步骤。另外，本申请图5-图8、图10-图14中的步骤在实际实现时可以更多或更少，各个步骤之间的先后顺序可以为其他，图中仅仅是给出了步骤之间的先后顺序的一种示例。
在上述实施例中，下行方向，通过将应用层序列号映射为GTP-U层序列号，再将GTP-U层序列号映射为PDCP层序列号，以便在第一接入网设备故障的情况下，实现第一接入网设备和第二接入网设备的顺利倒换。在第一接入网设备故障的情况下，第二接入网设备使用第二PDU会话传输数据，实现第一接入网设备和第二接入网设备的快速倒换，降低了第一接入网设备和第二接入网设备倒换时延，提高了数据传输的可靠性。
上述实施例以管理第一UPF的SMF和管理第二UPF的SMF为同一个SMF为例进行阐述的。在具体实现时，管理第一UPF的SMF和管理第二UPF的SMF也可以为不同的SMF，该情况下，上述与第一UPF直接或间接通信的SMF替换为管理第一UPF的SMF，与第二UPF直接或间接通信的SMF替换为管理第二UPF的SMF即可。
上述主要从方法的角度对本申请实施例的方案进行了介绍。可以理解的是，各个网元，例如，SMF、第一UPF、第二UPF、第一接入网设备、第二接入网设备、终端等为了实现上述功能，其包含了执行各个功能相应的硬件结构和软件模块中的至少一个。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。
本申请实施例可以根据上述方法示例对SMF、第一UPF、第二UPF、第一接入网设备、第二接入网设备、终端等进行功能单元的划分，例如，可以对应各个功能划分各个功能单元，也可以将两个或两个以上的功能集成在一个处理单元中。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，本申请实施例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。
示例性的，图15示出了上述实施例中所涉及的通信装置(记为通信装置150)的一种可能的结构示意图，该通信装置150包括处理单元1501。可选的，还包括通信单元1502和/或存储单元1503。图15所示的结构示意图可以用于示意上述实施例中所涉及的SMF、第一UPF、第二UPF、第一接入网设备、第二接入网设备、终端等的结构。
当图15所示的结构示意图用于示意上述实施例中所涉及的SMF的结构时，处理单元1501用于对SMF的动作进行控制管理，例如，处理单元1501用于执行图5中的501和502，图6中的各个步骤，图7中的501、502、507b和510，图8中的803和804，图11中的1103-1111以及1115-1117，图12中的1203-1211、1215-1217以及1219，图13中的1303-1311以及1315-1317，图14中的1403-1411、1415-1417以及1419，和/或本申请实施例中所描述的其他过程中的SMF执行的动作。处理单元1501 可以通过通信单元1502与其他网络实体通信，例如，与图5中的第一UPF通信。存储单元1503用于存储SMF的程序代码和数据。
当图15所示的结构示意图用于示意上述实施例中所涉及的第一UPF的结构时，处理单元1501用于对第一UPF的动作进行控制管理，例如，处理单元1501用于执行图5中的501、503和504，图6中的501，图7中的501、503和504，图8中的803和805，图11中的1110a、1110b、1116a、1116b，图13中的1310a、1310b、1316a、1316b，和/或本申请实施例中所描述的其他过程中的第一UPF执行的动作。处理单元1501可以通过通信单元1502与其他网络实体通信，例如，与图5中示出的SMF通信。存储单元1503用于存储第一UPF的程序代码和数据。
当图15所示的结构示意图用于示意上述实施例中所涉及的第二UPF的结构时，处理单元1501用于对第二UPF的动作进行控制管理，例如，处理单元1501用于执行图5中的502、505和506，图6中的502，图7中的502、505和506，图8中的801b、802b、802c、804和805，图10中的1003b、1002b和1002c，图12中的1210a、1210b、1216a、1216b和1219，图14中的1410a、1410b、1416a、1416b和1419，和/或本申请实施例中所描述的其他过程中的第二UPF执行的动作。处理单元1501可以通过通信单元1502与其他网络实体通信，例如，与图5中示出的SMF通信。存储单元1503用于存储第二UPF的程序代码和数据。
当图15所示的结构示意图用于示意上述实施例中所涉及的第一接入网设备的结构时，处理单元1501用于对第一接入网设备的动作进行控制管理，例如，处理单元1501用于执行图5中的504，图6中的500a，图7中的504、507a、507b和510，图11中的1101以及1112-1114，图12中的1201、1212-1214以及1219，图13中的1301以及1312-1314，图14中的1401、1412-1414以及1419，和/或本申请实施例中所描述的其他过程中的第一接入网设备执行的动作。处理单元1501可以通过通信单元1502与其他网络实体通信，例如，与图5中示出的SMF通信。存储单元1503用于存储第一接入网设备的程序代码和数据。
当图15所示的结构示意图用于示意上述实施例中所涉及的第二接入网设备的结构时，处理单元1501用于对第二接入网设备的动作进行控制管理，例如，处理单元1501用于执行图5中的506，图7中的506，图8中的801a、801b、801c、802a、802b、802c和802d，图10中的各个步骤，图12中的1218和1219，图14中的1418和1419，和/或本申请实施例中所描述的其他过程中的第二接入网设备执行的动作。处理单元1501可以通过通信单元1502与其他网络实体通信，例如，与图5中示出的SMF通信。存储单元1503用于存储第二接入网设备的程序代码和数据。
当图15所示的结构示意图用于示意上述实施例中所涉及的终端的结构时，处理单元1501用于对终端的动作进行控制管理，例如，处理单元1501用于执行图6中的500b和500c，图7中的507a、507b、508和509，图8中的801a、802a和802d，图10中的1001a、1003a、1002a和1002d，图11中的1101和1113，图12中的1201、1213和1219，图13中的1301和1313，图14中的1401、1413和1419，和/或本申请实施例中所描述的其他过程中的终端执行的动作。处理单元1501可以通过通信单元1502与其他网络实体通信，例如，与图11中示出的第一接入网设备通信。存储单元1503 用于存储终端的程序代码和数据。
图15所示的结构示意图还可以用于示意本申请涉及的其他网元(例如，AMF)的结构，该情况下，图15中的各个单元用于执行相应网元的动作，具体可参考方法部分进行理解，此处不再赘述。
其中，通信装置150可以是一个设备也可以是设备内的芯片。当通信装置150为一个设备时，处理单元1501可以是处理器或控制器，通信单元1502可以是通信接口、收发器、收发机、收发电路、收发装置等。其中，通信接口是统称，可以包括一个或多个接口。存储单元1503可以是存储器。当通信装置150为设备内的芯片时，处理单元1501可以是处理器或控制器，通信单元1502可以是输入接口和/或输出接口、管脚或电路等。存储单元1503可以是该芯片内的存储单元(例如，寄存器、缓存等)，也可以是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)。
其中，通信单元也可以称为收发单元。通信装置150中的具有收发功能的天线和控制电路可以视为通信装置150的通信单元1502，具有处理功能的处理器可以视为通信装置150的处理单元1501。可选的，通信单元1502中用于实现接收功能的器件可以视为接收单元，接收单元用于执行本申请实施例中的接收的步骤，接收单元可以为接收机、接收器、接收电路等。通信单元1502中用于实现发送功能的器件可以视为发送单元，发送单元用于执行本申请实施例中的发送的步骤，发送单元可以为发送机、发送器、发送电路等。
图15中的集成的单元如果以软件功能模块的形式实现并作为独立的产品销售或使用时，可以存储在一个计算机可读取存储介质中。基于这样的理解，本申请实施例的技术方案本质上或者说对现有技术做出贡献的部分或者该技术方案的全部或部分可以以软件产品的形式体现出来，该计算机软件产品存储在一个存储介质中，包括若干指令用以使得一台计算机设备(可以是个人计算机，服务器，或者网络设备等)或处理器(processor)执行本申请各个实施例所述方法的全部或部分步骤。存储计算机软件产品的存储介质包括：U盘、移动硬盘、只读存储器(read-only memory，ROM)、随机存取存储器(random access memory，RAM)、磁碟或者光盘等各种可以存储程序代码的介质。
本申请实施例还提供了一种通信装置的硬件结构示意图，参见图16或图17，该通信装置包括处理器1601，可选的，还包括与处理器1601连接的存储器1602。
处理器1601可以是一个通用中央处理器(central processing unit，CPU)、微处理器、特定应用集成电路(application-specific integrated circuit，ASIC)，或者一个或多个用于控制本申请方案程序执行的集成电路。处理器1601也可以包括多个CPU，并且处理器1601可以是一个单核(single-CPU)处理器，也可以是多核(multi-CPU)处理器。这里的处理器可以指一个或多个设备、电路或用于处理数据(例如计算机程序指令)的处理核。
存储器1602可以是ROM或可存储静态信息和指令的其他类型的静态存储设备、RAM或者可存储信息和指令的其他类型的动态存储设备，也可以是电可擦可编程只读存储器(electrically erasable programmable read-only memory，EEPROM)、只读光盘(compact disc read-only memory，CD-ROM)或其他光盘存储、光碟存储(包括压缩 光碟、激光碟、光碟、数字通用光碟、蓝光光碟等)、磁盘存储介质或者其他磁存储设备、或者能够用于携带或存储具有指令或数据结构形式的期望的程序代码并能够由计算机存取的任何其他介质，本申请实施例对此不作任何限制。存储器1602可以是独立存在，该情况下，存储器1602可以位于通信装置内，也可以位于通信装置外。存储器1602也可以和处理器1601集成在一起。其中，存储器1602中可以包含计算机程序代码。处理器1601用于执行存储器1602中存储的计算机程序代码，从而实现本申请实施例提供的方法。
在第一种可能的实现方式中，参见图16，通信装置还包括收发器1603。处理器1601、存储器1602和收发器1603通过总线相连接。收发器1603用于与其他设备或通信网络通信。可选的，收发器1603可以包括发射机和接收机。收发器1603中用于实现接收功能的器件可以视为接收机，接收机用于执行本申请实施例中的接收的步骤。收发器1603中用于实现发送功能的器件可以视为发射机，发射机用于执行本申请实施例中的发送的步骤。
基于第一种可能的实现方式，图16所示的结构示意图可以用于示意上述实施例中所涉及的SMF、第一UPF、第二UPF、第一接入网设备、第二接入网设备、终端等的结构。处理器1601可以用于实现图15中处理单元1501的功能，存储器1602用于实现图15中存储单元1503的功能，收发器1603用于实现图15中通信单元1502的功能。图16所示的结构示意图还可以用于示意本申请涉及的其他网元(例如，AMF等)的结构，该情况下，图16中的各个器件用于执行相应网元的动作，具体可参考方法部分进行理解，此处不再赘述。
在第二种可能的实现方式中，处理器1601包括逻辑电路，以及输入接口和/或输出接口。其中，输出接口用于执行相应方法中的发送的动作，输入接口用于执行相应方法中的接收的动作。基于第二种可能的实现方式，参见图17，图17所示的结构示意图可以用于示意上述实施例中所涉及的SMF、第一UPF、第二UPF、第一接入网设备、第二接入网设备、终端等的结构。
当图17所示的结构示意图用于示意上述实施例中所涉及的SMF的结构时，处理器1601用于对SMF的动作进行控制管理，例如，处理器1601用于执行图5中的501和502，图6中的各个步骤，图7中的501、502、507b和510，图8中的803和804，图11中的1103-1111以及1115-1117，图12中的1203-1211、1215-1217以及1219，图13中的1303-1311以及1315-1317，图14中的1403-1411、1415-1417以及1419，和/或本申请实施例中所描述的其他过程中的SMF执行的动作。处理器1601可以通过输入接口和/或输出接口与其他网络实体通信，例如，与图5中的第一UPF通信。存储器1602用于存储SMF的程序代码和数据。
当图17所示的结构示意图用于示意上述实施例中所涉及的第一UPF的结构时，处理器1601用于对第一UPF的动作进行控制管理，例如，处理器1601用于执行图5中的501、503和504，图6中的501，图7中的501、503和504，图8中的803和805，图11中的1110a、1110b、1116a、1116b，图13中的1310a、1310b、1316a、1316b，和/或本申请实施例中所描述的其他过程中的第一UPF执行的动作。处理器1601可以通过输入接口和/或输出接口与其他网络实体通信，例如，与图5中示出的SMF通信。 存储器1602用于存储第一UPF的程序代码和数据。
当图17所示的结构示意图用于示意上述实施例中所涉及的第二UPF的结构时，处理器1601用于对第二UPF的动作进行控制管理，例如，处理器1601用于执行图5中的502、505和506，图6中的502，图7中的502、505和506，图8中的801b、802b、802c、804和805，图10中的1003b、1002b和1002c，图12中的1210a、1210b、1216a、1216b和1219，图14中的1410a、1410b、1416a、1416b和1419，和/或本申请实施例中所描述的其他过程中的第二UPF执行的动作。处理器1601可以通过输入接口和/或输出接口与其他网络实体通信，例如，与图5中示出的SMF通信。存储器1602用于存储第二UPF的程序代码和数据。
当图17所示的结构示意图用于示意上述实施例中所涉及的第一接入网设备的结构时，处理器1601用于对第一接入网设备的动作进行控制管理，例如，处理器1601用于执行图5中的504，图6中的500a，图7中的504、507a、507b和510，图11中的1101以及1112-1114，图12中的1201、1212-1214以及1219，图13中的1301以及1312-1314，图14中的1401、1412-1414以及1419，和/或本申请实施例中所描述的其他过程中的第一接入网设备执行的动作。处理器1601可以通过输入接口和/或输出接口与其他网络实体通信，例如，与图5中示出的SMF通信。存储器1602用于存储第一接入网设备的程序代码和数据。
当图17所示的结构示意图用于示意上述实施例中所涉及的第二接入网设备的结构时，处理器1601用于对第二接入网设备的动作进行控制管理，例如，处理器1601用于执行图5中的506，图7中的506，图8中的801a、801b、801c、802a、802b、802c和802d，图10中的各个步骤，图12中的1218和1219，图14中的1418和1419，和/或本申请实施例中所描述的其他过程中的第二接入网设备执行的动作。处理器1601可以通过输入接口和/或输出接口与其他网络实体通信，例如，与图5中示出的SMF通信。存储器1602用于存储第二接入网设备的程序代码和数据。
当图17所示的结构示意图用于示意上述实施例中所涉及的终端的结构时，处理器1601用于对终端的动作进行控制管理，例如，处理器1601用于执行图6中的500b和500c，图7中的507a、507b、508和509，图8中的801a、802a和802d，图10中的1001a、1003a、1002a和1002d，图11中的1101和1113，图12中的1201、1213和1219，图13中的1301和1313，图14中的1401、1413和1419，和/或本申请实施例中所描述的其他过程中的终端执行的动作。处理器1601可以通过输入接口和/或输出接口与其他网络实体通信，例如，与图11中示出的第一接入网设备通信。存储器1602用于存储终端的程序代码和数据。
图17所示的结构示意图还可以用于示意本申请涉及的其他网元(例如，AMF等)的结构，该情况下，图17中的各个器件用于执行相应网元的动作，具体可参考方法部分进行理解，此处不再赘述。
本申请实施例还提供了一种计算机可读存储介质，包括指令，当其在计算机上运行时，使得计算机执行上述任一方法。
本申请实施例还提供了一种包含指令的计算机程序产品，当其在计算机上运行时，使得计算机执行上述任一方法。
本申请实施例还提供了一种通信装置，包括：处理器和接口，处理器通过接口与存储器耦合，当处理器执行存储器中的计算机程序或计算机执行指令时，使得上述任一方法被执行。
本申请实施例还提供了一种通信系统，包括：本申请实施例涉及的至少两个网元，例如，上述SMF、第一UPF、第二UPF、第一接入网设备、第二接入网设备和终端中的一个或多个。
上述实施例以本申请提供的方法应用在5G系统中为例进行阐述的。上述SMF可以替换为会话管理网元，UPF可以替换为用户面网元，DN可以替换为数据网络，其他网元也依据网元功能进行相应的替换即可。
在上述实施例中，可以全部或部分地通过软件、硬件、固件或者其任意组合来实现。当使用软件程序实现时，可以全部或部分地以计算机程序产品的形式来实现。该计算机程序产品包括一个或多个计算机指令。在计算机上加载和执行计算机程序指令时，全部或部分地产生按照本申请实施例所述的流程或功能。计算机可以是通用计算机、专用计算机、计算机网络、或者其他可编程装置。计算机指令可以存储在计算机可读存储介质中，或者从一个计算机可读存储介质向另一个计算机可读存储介质传输，例如，计算机指令可以从一个网站站点、计算机、服务器或者数据中心通过有线(例如同轴电缆、光纤、数字用户线(digital subscriber line，DSL))或无线(例如红外、无线、微波等)方式向另一个网站站点、计算机、服务器或数据中心进行传输。计算机可读存储介质可以是计算机能够存取的任何可用介质或者是包含一个或多个可以用介质集成的服务器、数据中心等数据存储设备。可用介质可以是磁性介质(例如，软盘、硬盘、磁带)，光介质(例如，DVD)、或者半导体介质(例如固态硬盘(solid state disk，SSD))等。
尽管在此结合各实施例对本申请进行了描述，然而，在实施所要求保护的本申请过程中，本领域技术人员通过查看附图、公开内容、以及所附权利要求书，可理解并实现公开实施例的其他变化。在权利要求中，“包括”(comprising)一词不排除其他组成部分或步骤，“一”或“一个”不排除多个的情况。单个处理器或其他单元可以实现权利要求中列举的若干项功能。相互不同的从属权利要求中记载了某些措施，但这并不表示这些措施不能组合起来产生良好的效果。
尽管结合具体特征及其实施例对本申请进行了描述，显而易见的，在不脱离本申请的精神和范围的情况下，可对其进行各种修改和组合。相应地，本说明书和附图仅仅是所附权利要求所界定的本申请的示例性说明，且视为已覆盖本申请范围内的任意和所有修改、变化、组合或等同物。显然，本领域的技术人员可以对本申请进行各种改动和变型而不脱离本申请的精神和范围。这样，倘若本申请的这些修改和变型属于本申请权利要求及其等同技术的范围之内，则本申请也意图包含这些改动和变型在内。

Claims (31)

  1. 一种通信方法，其特征在于，包括：
    会话管理网元向第一用户面网元发送第一指示信息，所述第一指示信息用于指示所述第一用户面网元通过第一映射规则进行下行数据包的应用层序列号和通用分组无线服务隧道协议用户面GTP-U层序列号的映射；
    所述会话管理网元向第二用户面网元发送第二指示信息，所述第二指示信息用于指示所述第二用户面网元通过所述第一映射规则进行下行数据包的应用层序列号和GTP-U层序列号的映射；
    其中，终端建立了第一协议数据单元PDU会话和第二PDU会话与数据网络通信，所述第一用户面网元和所述第二用户面网元分别为所述第一PDU会话和所述第二PDU会话的锚定点，所述终端接入的接入网设备包括第一接入网设备和第二接入网设备，所述第一接入网设备和所述第二接入网设备具有相同的小区配置；
    其中，在所述第一用户面网元接收到的第一下行数据包的应用层序列号与所述第二用户面网元接收到的第二下行数据包的应用层序列号相同的情况下，所述第一用户面网元向所述第一接入网设备发送的第一下行数据包的GTP-U层序列号与所述第二用户面网元向所述第二接入网设备发送的第二下行数据包的GTP-U层序列号相同。
  2. 根据权利要求1所述的方法，其特征在于，所述第一指示信息和所述第二指示信息还用于指示所述第一映射规则。
  3. 根据权利要求1或2所述的方法，其特征在于，所述方法还包括：
    所述会话管理网元向所述终端发送第三指示信息，所述第三指示信息用于指示所述终端仅在所述第一PDU会话上发送上行数据包。
  4. 根据权利要求1-3任一项所述的方法，其特征在于，所述方法还包括：
    所述会话管理网元从所述第一用户面网元接收所述第一用户面网元的隧道信息，所述第一用户面网元的隧道信息包括所述第一用户面网元的隧道端点标识和网络互连协议IP地址；
    所述会话管理网元向所述第二用户面网元发送所述第一用户面网元的隧道信息，用于所述第二用户面网元根据所述第一用户面网元的隧道信息转发所述第一PDU会话的上行数据包到所述第一用户面网元。
  5. 根据权利要求1-4任一项所述的方法，其特征在于，在所述会话管理网元向第一用户面网元发送第一指示信息之前，所述方法还包括：
    所述会话管理网元从所述第一接入网设备接收第四指示信息，所述第四指示信息用于指示进行下行数据包的应用层序列号和GTP-U层序列号的映射。
  6. 一种通信方法，其特征在于，包括：
    第二用户面网元从会话管理网元接收第二指示信息，所述第二指示信息用于指示所述第二用户面网元通过第一映射规则进行下行数据包的应用层序列号和通用分组无线服务隧道协议用户面GTP-U层序列号的映射；其中，所述第二用户面网元为第二协议数据单元PDU会话的锚定点；
    在接收到所述第二PDU会话的第二下行数据包时，所述第二用户面网元根据所述第一映射规则进行所述第二下行数据包的应用层序列号和GTP-U层序列号的映射；
    所述第二用户面网元发送所述第二下行数据包。
  7. 根据权利要求6所述的方法，其特征在于，所述第二指示信息还用于指示所述第一映射规则。
  8. 根据权利要求6或7所述的方法，其特征在于，所述方法还包括：
    所述第二用户面网元从所述会话管理网元接收第一用户面网元的隧道信息，所述第一用户面网元的隧道信息包括所述第一用户面网元的隧道端点标识和网络互连协议IP地址，所述第一用户面网元为所述第一PDU会话的锚定点，所述第一PDU会话和所述第二PDU会话互为冗余会话；
    在接收到所述第一PDU会话的上行数据包时，所述第二用户面网元根据所述第一用户面网元的隧道信息向所述第一用户面网元发送所述第一PDU会话的上行数据包。
  9. 一种通信方法，其特征在于，包括：
    在未检测到第一接入网设备故障的情况下，第二接入网设备接收终端通过第一协议数据单元PDU会话发送的第一上行数据包和第二用户面网元通过第二PDU会话发送的第三下行数据包，并缓存所述第一上行数据包和所述第三下行数据包；其中，所述第一接入网设备和所述第二接入网设备具有相同的小区配置，所述终端建立了所述第一PDU会话和所述第二PDU会话与数据网络通信，第一用户面网元和所述第二用户面网元分别为所述第一PDU会话和所述第二PDU会话的锚定点；
    在检测到所述第一接入网设备故障的情况下，所述第二接入网设备接收所述终端通过所述第一PDU会话发送的第二上行数据包，并发送给所述第二用户面网元；所述第二接入网设备接收所述第二用户面网元通过所述第二PDU会话发送的第四下行数据包并发送给所述终端。
  10. 一种通信方法，其特征在于，包括：
    在未检测到第一接入网设备故障的情况下，第二接入网设备接收终端通过第一PDU会话发送的第三上行数据包，并丢弃所述第三上行数据包；其中，所述第一接入网设备和所述第二接入网设备具有相同的小区配置，所述终端通过所述第一PDU会话和第二PDU会话与数据网络通信，所述第一PDU会话和所述第二PDU会话的锚定点分别为第一用户面网元和第二用户面网元；
    在检测到所述第一接入网设备故障的情况下，所述第二接入网设备接收所述终端通过所述第二PDU会话发送的第四上行数据包，并发送给所述第二用户面网元；所述第二接入网设备接收所述第二用户面网元通过所述第二PDU会话发送的第五下行数据包并发送给所述终端。
  11. 根据权利要求10所述的方法，其特征在于，所述方法还包括：
    在未检测到所述第一接入网设备故障的情况下，所述第二接入网设备接收所述终端通过所述第二PDU会话发送的第五上行数据包和所述第二用户面网元通过所述第二PDU会话发送的第六下行数据包，并缓存所述第五上行数据包和所述第六下行数据包。
  12. 一种通信方法，其特征在于，包括：
    终端从第一接入网设备或会话管理网元接收第三指示信息，所述第三指示信息用于指示所述终端仅在第一协议数据单元PDU会话上发送上行数据包，所述终端建立了 所述第一PDU会话和第二PDU会话与数据网络通信，所述第一PDU会话和所述第二PDU会话互为冗余会话；
    所述终端在所述第一PDU会话上发送所述上行数据包。
  13. 根据权利要求12所述的方法，其特征在于，所述方法还包括：
    所述终端根据所述第三指示信息丢弃所述第二PDU会话上的上行数据包。
  14. 根据权利要求12或13所述的方法，其特征在于，所述方法还包括：
    所述终端向所述会话管理网元发送第二PDU会话建立请求，所述第二PDU会话建立请求用于请求建立所述第二PDU会话，所述第二PDU会话建立请求中包括所述第一PDU会话的标识。
  15. 根据权利要求14所述的方法，其特征在于，所述第一PDU会话的标识用于指示所述第一PDU会话和所述第二PDU会话互为冗余会话。
  16. 一种通信装置，其特征在于，包括：处理单元和通信单元；
    所述处理单元，用于通过所述通信单元向第一用户面网元发送第一指示信息，所述第一指示信息用于指示所述第一用户面网元通过第一映射规则进行下行数据包的应用层序列号和通用分组无线服务隧道协议用户面GTP-U层序列号的映射；
    所述处理单元，还用于通过所述通信单元向第二用户面网元发送第二指示信息，所述第二指示信息用于指示所述第二用户面网元通过所述第一映射规则进行下行数据包的应用层序列号和GTP-U层序列号的映射；
    其中，终端建立了第一协议数据单元PDU会话和第二PDU会话与数据网络通信，所述第一用户面网元和所述第二用户面网元分别为所述第一PDU会话和所述第二PDU会话的锚定点，所述终端接入的接入网设备包括第一接入网设备和第二接入网设备，所述第一接入网设备和所述第二接入网设备具有相同的小区配置；
    其中，在所述第一用户面网元接收到的第一下行数据包的应用层序列号与所述第二用户面网元接收到的第二下行数据包的应用层序列号相同的情况下，所述第一用户面网元向所述第一接入网设备发送的第一下行数据包的GTP-U层序列号与所述第二用户面网元向所述第二接入网设备发送的第二下行数据包的GTP-U层序列号相同。
  17. 根据权利要求16所述的通信装置，其特征在于，所述第一指示信息和所述第二指示信息还用于指示所述第一映射规则。
  18. 根据权利要求16或17所述的通信装置，其特征在于，
    所述处理单元，还用于通过所述通信单元向所述终端发送第三指示信息，所述第三指示信息用于指示所述终端仅在所述第一PDU会话上发送上行数据包。
  19. 根据权利要求16-18任一项所述的通信装置，其特征在于，
    所述处理单元，还用于通过所述通信单元从所述第一用户面网元接收所述第一用户面网元的隧道信息，所述第一用户面网元的隧道信息包括所述第一用户面网元的隧道端点标识和网络互连协议IP地址；
    所述处理单元，还用于通过所述通信单元向所述第二用户面网元发送所述第一用户面网元的隧道信息，用于所述第二用户面网元根据所述第一用户面网元的隧道信息转发所述第一PDU会话的上行数据包到所述第一用户面网元。
  20. 根据权利要求16-19任一项所述的通信装置，其特征在于，
    所述处理单元，还用于通过所述通信单元从所述第一接入网设备接收第四指示信息，所述第四指示信息用于指示进行下行数据包的应用层序列号和GTP-U层序列号的映射。
  21. 一种通信装置，其特征在于，包括：处理单元和通信单元；
    所述通信单元，用于从会话管理网元接收第二指示信息，所述第二指示信息用于指示所述通信装置通过第一映射规则进行下行数据包的应用层序列号和通用分组无线服务隧道协议用户面GTP-U层序列号的映射；其中，所述通信装置为第二协议数据单元PDU会话的锚定点；
    在接收到所述第二PDU会话的第二下行数据包时，所述处理单元，用于根据所述第一映射规则进行所述第二下行数据包的应用层序列号和GTP-U层序列号的映射；
    所述通信单元，还用于发送所述第二下行数据包。
  22. 根据权利要求21所述的通信装置，其特征在于，所述第二指示信息还用于指示所述第一映射规则。
  23. 根据权利要求21或22所述的通信装置，其特征在于，
    所述通信单元，还用于从所述会话管理网元接收第一用户面网元的隧道信息，所述第一用户面网元的隧道信息包括所述第一用户面网元的隧道端点标识和网络互连协议IP地址，所述第一用户面网元为所述第一PDU会话的锚定点，所述第一PDU会话和所述第二PDU会话互为冗余会话；
    在接收到所述第一PDU会话的上行数据包时，所述通信单元，还用于根据所述第一用户面网元的隧道信息向所述第一用户面网元发送所述第一PDU会话的上行数据包。
  24. 一种通信装置，其特征在于，包括：处理单元和通信单元；
    在未检测到第一接入网设备故障的情况下，所述处理单元，用于通过所述通信单元接收终端通过第一协议数据单元PDU会话发送的第一上行数据包和第二用户面网元通过第二PDU会话发送的第三下行数据包，并缓存所述第一上行数据包和所述第三下行数据包；其中，所述第一接入网设备和所述通信装置具有相同的小区配置，所述终端建立了所述第一PDU会话和所述第二PDU会话与数据网络通信，第一用户面网元和所述第二用户面网元分别为所述第一PDU会话和所述第二PDU会话的锚定点；
    在检测到所述第一接入网设备故障的情况下，所述处理单元，还用于通过所述通信单元接收所述终端通过所述第一PDU会话发送的第二上行数据包，并发送给所述第二用户面网元；所述处理单元，还用于通过所述通信单元接收所述第二用户面网元通过所述第二PDU会话发送的第四下行数据包并发送给所述终端。
  25. 一种通信装置，其特征在于，包括：处理单元和通信单元；
    在未检测到第一接入网设备故障的情况下，所述处理单元，用于通过所述通信单元接收终端通过第一PDU会话发送的第三上行数据包，并丢弃所述第三上行数据包；其中，所述第一接入网设备和所述通信装置具有相同的小区配置，所述终端通过所述第一PDU会话和第二PDU会话与数据网络通信，所述第一PDU会话和所述第二PDU会话的锚定点分别为第一用户面网元和第二用户面网元；
    在检测到所述第一接入网设备故障的情况下，所述处理单元，还用于通过所述通 信单元接收所述终端通过所述第二PDU会话发送的第四上行数据包，并发送给所述第二用户面网元；所述处理单元，还用于通过所述通信单元接收所述第二用户面网元通过所述第二PDU会话发送的第五下行数据包并发送给所述终端。
  26. 根据权利要求25所述的通信装置，其特征在于，
    在未检测到所述第一接入网设备故障的情况下，所述处理单元，还用于通过所述通信单元接收所述终端通过所述第二PDU会话发送的第五上行数据包和所述第二用户面网元通过所述第二PDU会话发送的第六下行数据包，并缓存所述第五上行数据包和所述第六下行数据包。
  27. 一种通信装置，其特征在于，包括：处理单元和通信单元；
    所述处理单元，用于通过所述通信单元从第一接入网设备或会话管理网元接收第三指示信息，所述第三指示信息用于指示所述通信装置仅在第一协议数据单元PDU会话上发送上行数据包，所述通信装置建立了所述第一PDU会话和第二PDU会话与数据网络通信，所述第一PDU会话和所述第二PDU会话互为冗余会话；
    所述处理单元，还用于通过所述通信单元在所述第一PDU会话上发送所述上行数据包。
  28. 根据权利要求27所述的通信装置，其特征在于，
    所述处理单元，还用于根据所述第三指示信息丢弃所述第二PDU会话上的上行数据包。
  29. 根据权利要求27或28所述的通信装置，其特征在于，
    所述处理单元，还用于通过所述通信单元向所述会话管理网元发送第二PDU会话建立请求，所述第二PDU会话建立请求用于请求建立所述第二PDU会话，所述第二PDU会话建立请求中包括所述第一PDU会话的标识。
  30. 根据权利要求29所述的通信装置，其特征在于，所述第一PDU会话的标识用于指示所述第一PDU会话和所述第二PDU会话互为冗余会话。
  31. 一种通信装置，其特征在于，包括：处理器；
    所述处理器与存储器连接，所述存储器用于存储计算机执行指令，所述处理器执行所述存储器存储的所述计算机执行指令，以使所述通信装置实现如权利要求1-5任一项所述的方法，或者，以使所述通信装置实现如权利要求6-8任一项所述的方法，或者，以使所述通信装置实现如权利要求9所述的方法，或者，以使所述通信装置实现如权利要求10或11所述的方法，或者，以使所述通信装置实现如权利要求12-15任一项所述的方法。
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