Abstract: This application provides a link quality obtaining method and apparatus. One method performed by a session management network element includes: determining a monitoring link for monitoring quality of service (QoS) of a service path between a first communications device and a second communications device; sending a first link quality reporting request to the first communications device, wherein the first link quality reporting request indicates the first communications device to report QoS information of the service path in response to one or more reporting conditions being satisfied; and receiving a first link quality notification message from the first communications device, wherein the first link quality notification message comprises the QoS information and an identifier of the monitoring link.

Abstract: A service continuity implementation method, a device, and a service continuity implementation system, to ensure service continuity in a handover process, where the method includes: selecting, by a session management function entity, a target user plane function entity to serve a terminal; sending, by the session management function entity, a first message to a control device; receiving, by the session management function entity, indication information of a first application server (AS) from the control device; and sending, by the session management function entity, a first routing rule to the target user plane function entity based on the indication information of the first AS, where the first routing rule specifies that data whose destination address is an address of the first AS is to be sent to the first AS.

Abstract: A method and an apparatus for initiating user plane path re-establishment and a communications system are disclosed. The method includes: determining, by a session management function entity based on first location information of a terminal device, a session service area to which a current session of the terminal device belongs; and after receiving second location information of the terminal device sent by a mobility management function entity, if determining that the second location information is not within the session service area, instructing the terminal device to initiate a re-establishment procedure for the current session or initiate a handover procedure. Due to introduction of the session service area, when the terminal device moves back and forth at edges of service areas of two adjacent user plane function entities, a ping-pong effect caused by frequent handover between the two user plane function entities is avoided, and user experience is improved.

Abstract: A communication method, an apparatus, and a system in which a first session management function entity determines, based on information of a terminal group, user plane function entities accessed by terminals in a terminal group, and the first session management function entity determines a target user plane function entity based on the user plane function entities, where the target user plane function entity is used to perform communication between terminals in the terminal group. According to the method, the terminals in the terminal group are redirected to a same user plane function entity, namely, the target user plane function entity, so that communication between the terminals in the terminal group is locally implemented in the target user plane function entity. This shortens a communication path, and reduces a communication latency.

Abstract: A method for detecting quality of service of a service includes obtaining, by a packet sending device, detection indication information, where the detection indication information is used to instruct the packet sending device to detect quality of service of a service; and sending, by the packet sending device, a detection packet to a packet receiving device based on the detection indication information, where the detection packet is used to detect the quality of service of the service.

Abstract: A communication method, an apparatus, and a system in which a first session management function entity based on information of a terminal group determines user plane function entities accessed by terminals in a terminal group, and the first session management function entity determines a target user plane function entity based on the user plane function entities, where the target user plane function entity is used to perform communication between terminals in the terminal group. According to the method, the terminals in the terminal group are redirected to a same user plane function entity, namely, the target user plane function entity, so that communication between the terminals in the terminal group is locally implemented in the target user plane function entity. This shortens a communication path, and reduces a communication latency.

Abstract: This application provides a server switching method and apparatus, and a communications system. The method includes: receiving, by a terminal, a first notification message, where the first notification message includes an address of a second server; sending, by the terminal, to-be-sent service data to a first server and the second server based on the first notification message; receiving, by the terminal, downlink data from the first server; obtaining, by the terminal, data processing indication information; when obtaining the data processing indication information, sending, by the terminal, the to-be-sent service data to the second server; and receiving, by the terminal, downlink data from the second server. The server switching method and apparatus, and the communications system in the embodiments of this application can implement seamless switching, ensure service continuity, avoid service interruption caused when a terminal switches between servers, and help meet an end-to-end latency requirement.

Abstract: Embodiments of the present disclosure provide a session establishment method and system, and a device, to meet a low-latency requirement of group communication. The method includes: obtaining, by a mobility management entity, group identification information of a group to which a terminal belongs; determining, by the mobility management entity based on the group identification information, a session management entity that serves the group to which the terminal belongs; and sending, by the mobility management entity, the group identification information to the session management entity, where the group identification information is used to determine a user plane function entity that serves the group to which the terminal belongs.

Abstract: Embodiments of the present disclosure provide a session establishment method and system, and a device, to meet a low-latency requirement of group communication. The method includes: obtaining, by a mobility management entity, group identification information of a group to which a terminal belongs; determining, by the mobility management entity based on the group identification information, a session management entity that serves the group to which the terminal belongs; and sending, by the mobility management entity, the group identification information to the session management entity, where the group identification information is used to determine a user plane function entity that serves the group to which the terminal belongs.

Abstract: A method for improving service reliability includes deciding, by a session function entity in a network, to initiate establishment of at least two transmission paths between a terminal and the user plane function entity, and instructing the terminal or the user plane function entity to transmit same data on the at least two paths. The user plane function allocates, based on a notification of the session function entity, user plane resources to the at least two transmission paths, and transmits the same data with the terminal on the at least two transmission paths. A core network initiates the establishment of the at least two transmission paths to the terminal. Two access devices may independently establish the at least two transmission paths.

Abstract: A method and an apparatus for initiating user plane path re-establishment and a communications system are disclosed. The method includes: determining, by a session management function entity based on first location information of a terminal device, a session service area to which a current session of the terminal device belongs; and after receiving second location information of the terminal device sent by a mobility management function entity, if determining that the second location information is not within the session service area, instructing the terminal device to initiate a re-establishment procedure for the current session or initiate a handover procedure. Due to introduction of the session service area, when the terminal device moves back and forth at edges of service areas of two adjacent user plane function entities, a ping-pong effect caused by frequent handover between the two user plane function entities is avoided, and user experience is improved.

Abstract: A method and an apparatus for initiating user plane path re-establishment and a communications system are disclosed. The method includes: determining, by a session management function entity based on first location information of a terminal device, a session service area to which a current session of the terminal device belongs; and after receiving second location information of the terminal device sent by a mobility management function entity, if determining that the second location information is not within the session service area, instructing the terminal device to initiate a re-establishment procedure for the current session or initiate a handover procedure. Due to introduction of the session service area, when the terminal device moves back and forth at edges of service areas of two adjacent user plane function entities, a ping-pong effect caused by frequent handover between the two user plane function entities is avoided, and user experience is improved.

Abstract: A service continuity implementation method, a device, and a service continuity implementation system, to ensure service continuity in a handover process, where the method includes: selecting, by a session management function entity, a target user plane function entity to serve a terminal; sending, by the session management function entity, a first message to a control device; receiving, by the session management function entity, indication information of a first application server (AS) from the control device; and sending, by the session management function entity, a first routing rule to the target user plane function entity based on the indication information of the first AS, where the first routing rule specifies that data whose destination address is an address of the first AS is to be sent to the first AS.

Abstract: A service continuity implementation method, a device, and a service continuity implementation system, to ensure service continuity in a handover process, where the method includes: selecting, by a session management function entity, a target user plane function entity to serve a terminal; sending, by the session management function entity, a first message to a control device; receiving, by the session management function entity, indication information of a first application server (AS) from the control device; and sending, by the session management function entity, a first routing rule to the target user plane function entity based on the indication information of the first AS, where the first routing rule specifies that data whose destination address is an address of the first AS is to be sent to the first AS.

Abstract: The wireless communication method in this application includes: receiving, by a first user plane function (UPF) entity, a first message sent by a session management function (SMF) entity, where the first message includes a multicast address of a group and session information of at least one second terminal; and duplicating, by the first UPF entity, received first service data to obtain N copies of first service data, and sending the duplicated first service data to each second terminal based on the multicast address and the session information of the at least one second terminal, where the first service data is data that is from a first terminal and whose destination address is the multicast address, and N is a total quantity of the at least one second terminal. Embodiments of this application can implement a wireless communication method applied to V2X.

Abstract: A method and system for detecting quality of service of a service, and a device, to detect quality of service of a service in real time. The method includes: generating, by a packet sending device, a first packet, where the first packet includes session information of a service and a packet type of the first packet; and sending, by the packet sending device, the first packet to a packet receiving device, where the first packet is used to detect at least one of quality of service of the service or segment quality of service of the service.

Abstract: This application provides a link quality obtaining method and apparatus. One method performed by a session management network element includes: determining a monitoring link for monitoring quality of service (QoS) of a service path between a first communications device and a second communications device; sending a first link quality reporting request to the first communications device, wherein the first link quality reporting request indicates the first communications device to report QoS information of the service path in response to one or more reporting conditions being satisfied; and receiving a first link quality notification message from the first communications device, wherein the first link quality notification message comprises the QoS information and an identifier of the monitoring link.

Abstract: This application provides a server switching method and apparatus, and a communications system. The method includes: receiving, by a terminal, a first notification message, where the first notification message includes an address of a second server; sending, by the terminal, to-be-sent service data to a first server and the second server based on the first notification message; receiving, by the terminal, downlink data from the first server; obtaining, by the terminal, data processing indication information; when obtaining the data processing indication information, sending, by the terminal, the to-be-sent service data to the second server; and receiving, by the terminal, downlink data from the second server. The server switching method and apparatus, and the communications system in the embodiments of this application can implement seamless switching, ensure service continuity, avoid service interruption caused when a terminal switches between servers, and help meet an end-to-end latency requirement.

Abstract: Embodiments of the present disclosure provide a session establishment method and system, and a device, to meet a low-latency requirement of group communication. The method includes: obtaining, by a mobility management entity, group identification information of a group to which a terminal belongs; determining, by the mobility management entity based on the group identification information, a session management entity that serves the group to which the terminal belongs; and sending, by the mobility management entity, the group identification information to the session management entity, where the group identification information is used to determine a user plane function entity that serves the group to which the terminal belongs.

Abstract: A method for improving service reliability includes deciding, by a session function entity in a network, to initiate establishment of at least two transmission paths between a terminal and the user plane function entity, and instructing the terminal or the user plane function entity to transmit same data on the at least two paths. The user plane function allocates, based on a notification of the session function entity, user plane resources to the at least two transmission paths, and transmits the same data with the terminal on the at least two transmission paths. A core network initiates the establishment of the at least two transmission paths to the terminal. Two access devices may independently establish the at least two transmission paths.