Method and device for determining SSC mode

Abstract

Disclosed are a method and device for determining an SSC mode, the method comprising: a terminal device determining a requested SSC mode, and sending a first request message to a first core network element, the first request message being used for requesting to establish a first PDU session, the first request message comprises a session type of the first PDU session, a requested SSC mode and first indication information; the first request message sent by the terminal equipment to the first core network element can carry the first indication information which is used for indicating that the SSC mode requested by the terminal equipment is not allowed to be modified, so that the network element on the subsequent network side is prevented from generating wrong decisions, for example, the requested SSC mode is modified into other SSC modes which are not supported by the terminal equipment.

Description

[0001] This application is a divisional application. The application number of the original application is 201980013139.0, and the original application date is February 13, 2019. The entire content of the original application is incorporated into this application by reference. Technical Field

[0002] The present invention relates to the field of wireless communication technology, and in particular to a method and device for determining an SSC mode. Background Art

[0003] The service and session continuity (SSC) mode is one of the attributes of a protocol data unit (PDU) session in a wireless communication system. The SSC mode typically has three values: SSC mode 1, SSC mode 2, and SSC mode 3. For an SSC mode 1 session, the PDU session anchor (PSA) remains unchanged for the duration of the session. For an SSC mode 2 session, the PSA can be switched by first releasing the old session and then creating a new one. For an SSC mode 3 session, the PSA can be switched by first creating a new session and then deleting the old one. The new and old sessions will coexist for a period of time.

[0004] In the R15 (Release 15) standard, for SSC mode 3 of Ethernet sessions and unstructured sessions, terminal devices cannot select new session transmission or old session transmission for uplink data during the coexistence period of the new and old sessions. Therefore, to reduce the complexity of the R15 version protocol, the SSC modes for Ethernet sessions and unstructured sessions are limited to SSC mode 1 and SSC mode 2, and SSC mode 3 cannot be used.

[0005] However, since the fifth-generation mobile communication system (5G) supports ultra-reliable low-latency communication (URLLC) services, and URLLC services provide high reliability and low latency based on Ethernet sessions, they need to support SSC mode 3. Therefore, to support URLLC services, Ethernet sessions must support SSC mode 3. This results in two types of terminal devices: R15 terminal devices, which do not support SSC mode 3 Ethernet sessions; and R16 terminal devices, which support SSC mode 3 Ethernet sessions. Correspondingly, there will be two types of 5G network capabilities: R15 5GC, which does not support SSC mode 3 Ethernet sessions; and R16 5GC, which supports SSC mode 3 Ethernet sessions. In this case, how to determine the SSC mode of a session requires further study. Summary of the Invention

[0006] The present application provides a method for determining an SSC mode, which is used to solve the technical problem that errors may be caused by determining the SSC mode in the prior art.

[0007] In a 5G network, each PDU session may include one or more of the following five attributes: Single Network Slice Selection Assistance Information (S-NSSAI), Data Network Name (DNN), PDU Session Type (PDU Session Type), Service and Session Continuity Mode (SSC Mode), and PDU Session Identifier (PDUSession ID). The PDU Session Identifier uniquely identifies a session on the UE. Specifically, PDU session types include IP sessions (IPv4 or IPv6), Ethernet sessions, and unstructured sessions; in the embodiments of the present application, Ethernet sessions and unstructured sessions are collectively referred to as Non-IP sessions.

[0008] In a first aspect, an embodiment of the present application provides a method for determining an SSC mode, the method comprising:

[0009] The terminal device determines the requested SSC mode;

[0010] The terminal device sends a first request message to the first core network network element, where the first request message is used to request the establishment of a first PDU session. The first request message includes the session type of the first PDU session and the requested SSC mode.

[0011] In one possible design, the first request message also includes first indication information, and the first indication information is used to indicate that the requested SSC mode is not allowed to be modified.

[0012] In this way, since the first request message sent by the terminal device to the first core network network element can carry the first indication information, it is used to indicate that the SSC mode requested by the terminal device is not allowed to be modified, thereby avoiding the subsequent network side network elements from making wrong decisions, such as modifying the requested SSC mode to other SSC modes not supported by the terminal device.

[0013] In one possible design, before the terminal device determines the requested SSC mode, the further steps include:

[0014] The terminal device sends capability information of the terminal device to the second core network network element, where the capability information of the terminal device is used to indicate whether the terminal device supports SSC mode 3 of the Non-IP session;

[0015] The terminal device receives first SSC mode restriction information from the second core network network element, where the first SSC mode restriction information is determined by capability information of the terminal device, subscription information of the terminal device, and network capability information, where the subscription information is used to indicate a session type and an associated SSC mode of a PDU session allowed by the terminal device, and the network capability information is used to indicate whether the network supports SSC mode 3 for a non-IP session;

[0016] The terminal device determines the requested SSC mode, including:

[0017] The terminal device determines the requested SSC mode based on the session type of the first PDU session and the first SSC mode restriction information.

[0018] In one possible design, the terminal device determines the requested SSC mode, including:

[0019] The terminal device receives first SSC mode restriction information from a third core network network element, where the first SSC mode restriction information is determined by capability information of the terminal device, subscription information of the terminal device, network capability information, and an AF policy, the capability information of the terminal device being used to indicate whether the terminal device supports SSC mode 3 for a Non-IP session, the subscription information being used to indicate a session type and an associated SSC mode of a PDU session allowed by the terminal device, the network capability information being used to indicate whether the network supports SSC mode 3 for a Non-IP session, and the AF policy including at least one application identifier and an associated SSC mode;

[0020] The terminal device determines the requested SSC mode based on the application identifier, the session type of the first PDU session and the first SSC mode restriction information.

[0021] In this way, since the first SSC mode restriction information is determined by multiple types of information, that is, information of multiple dimensions is fully considered, the first SSC mode restriction information is more reasonable and effective.

[0022] In one possible design, the requested SSC mode is the only SSC mode that satisfies the first SSC mode restriction information.

[0023] In this way, the SSC mode requested by the terminal device can be obtained by the terminal device based on the first SSC mode restriction information, so that the terminal device can determine whether the requested SSC mode is allowed to be modified, and if it is not allowed to be modified (that is, the requested SSC mode is the only SSC mode that meets the first SSC mode restriction information), the first indication information is carried in the first request message.

[0024] In one possible design, the terminal device determines the requested SSC mode, including:

[0025] The terminal device uses the SSC mode provided by the application as the requested SSC mode; or,

[0026] The terminal device obtains the requested SSC mode according to a default SSC mode selection policy rule.

[0027] In one possible design, after the terminal device sends the first request message to the first core network element, the method further includes:

[0028] The terminal device receives a first response message from the first core network element, where the first response message is used to indicate a refusal to establish the first PDU session.

[0029] In one possible design, the first response message includes reason information (cause code) for refusing to establish the first PDU session, and the cause information is used to indicate at least one of the following: the terminal device does not support the requested SSC mode; the network does not support the requested SSC mode; the data network DN does not support the requested SSC mode; the contract does not support the requested SSC mode.

[0030] In one possible design, after the terminal device receives the first response message from the first core network element, the further step includes:

[0031] If the cause information is used to indicate that the terminal device does not support the requested SSC mode and / or the subscription does not support the requested SSC mode, the terminal device determines the requested SSC mode as an SSC mode that is not associated with the session type of the first PDU session;

[0032] If the cause information is used to indicate that the network does not support the requested SSC mode, then when the accessed public land mobile network PLMN does not change, the terminal device determines the requested SSC mode as an SSC mode that is not associated with the session type of the first PDU session;

[0033] If the reason information is used to indicate that DN does not support the requested SSC mode, the terminal device determines the requested SSC mode as an SSC mode that is not associated with the session type of the first PDU session when the data network name DNN does not change.

[0034] In this way, since the first response message includes the reason information for rejecting the first PDU session, the terminal device can perform corresponding operations based on the reason information.

[0035] In one possible design, the first response message also includes the SSC mode allowed by the first PDU session.

[0036] In one possible design, after the terminal device receives the first response message from the first core network element, the further step includes:

[0037] The terminal device sends a fourth request message to the first core network network element based on the first response message, where the fourth request message is used to request establishment of the first PDU session, and the fourth request message includes the SSC mode allowed by the first PDU session.

[0038] In one possible design, the first core network element is an SMF network element, the second core network element is an AMF network element, and the third core network element is a PCF network element.

[0039] In a second aspect, an embodiment of the present application provides a method for determining an SSC mode, the method comprising:

[0040] The first core network element receives a first request message from the terminal device, where the first request message includes a session type of the first PDU session and a requested SSC mode;

[0041] The first core network element returns a first response message to the terminal device.

[0042] In one possible design, the first request message also includes first indication information, and the first indication information is used to indicate that the requested SSC mode is not allowed to be modified.

[0043] In one possible design, the first response message is used to indicate that the requested SSC mode is rejected.

[0044] In one possible design, before the first core network element returns a first response message to the terminal device, the method further includes:

[0045] The first core network network element obtains judgment information, where the judgment information includes one or more of the subscription information, network capability information, DN authentication information, and capability information of the terminal device; the subscription information is used to indicate a session type and an associated SSC mode of a PDU session allowed by the terminal device, the network capability information is used to indicate whether the network supports SSC mode 3 of a Non-IP session, the capability information of the terminal device is used to indicate whether the terminal device supports SSC mode 3 of a Non-IP session, and the DN authentication information is used to indicate a session type and an associated SSC mode of a PDU session supported by the DN;

[0046] The first core network element determines, based on the judgment information, that the requested SSC mode is not supported.

[0047] In one possible design, the first response message includes reason information for refusing to establish the first PDU session.

[0048] In one possible design, if the first core network element determines, based on the subscription information of the terminal device, that the requested SSC mode is not supported, the cause information indicates that the subscription does not support the requested SSC mode;

[0049] If the first core network element determines, based on the network capability information, that the requested SSC mode is not supported, the cause information indicates that the network does not support the requested SSC mode;

[0050] If the first core network element determines, based on the DN authentication information, that the requested SSC mode is not supported, the cause information indicates that the DN does not support the requested SSC mode;

[0051] If the first core network element determines that the requested SSC mode is not supported based on the capability information of the terminal device, the cause information indicates that the terminal device does not support the requested SSC mode.

[0052] In one possible design, the first response message also includes the SSC mode allowed by the first PDU session.

[0053] In one possible design, the first core network network element is an AMF network element or an SMF network element. Before the first core network network element returns a first response message to the terminal device, the method further includes:

[0054] The first core network element obtains first SSC mode restriction information, where the first SSC mode restriction information is determined by subscription information, network capability information, and capability information of the terminal device;

[0055] The first core network element determines that the requested SSC mode is not supported according to the first SSC mode restriction information.

[0056] Exemplarily, the first core network network element is an AMF network element. Before the first core network network element returns a first response message to the terminal device, the method also includes: the AMF network element obtains first SSC mode restriction information, and the first SSC mode restriction information is determined by the contract information, network capability information, and capability information of the terminal device; the AMF network element determines that the requested SSC mode is not supported based on the SSC mode restriction information.

[0057] Exemplarily, the first core network network element is an SMF network element. Before the first core network network element returns a first response message to the terminal device, the method also includes: the SMF network element receives first SSC mode restriction information from the PCF network element or the AMF network element, and the first SSC mode restriction information is determined by the contract information, network capability information, and capability information (and AF policy) of the terminal device; the SMF network element determines that the requested SSC mode is not supported based on the SSC mode restriction information.

[0058] In a third aspect, an embodiment of the present application provides a method for determining an SSC mode, the method comprising:

[0059] The second core network network element obtains capability information of the terminal device, subscription information of the terminal device, and network capability information; the capability information of the terminal device is used to indicate whether the terminal device supports SSC mode 3 of the non-IP session, the subscription information is used to indicate the session type and associated SSC mode of the PDU session allowed by the terminal device, and the network capability information is used to indicate whether the network supports SSC mode 3 of the non-IP session;

[0060] The second core network element obtains the first SSC mode restriction information based on the capability information of the terminal device, the subscription information of the terminal device and the network capability information.

[0061] Based on the third aspect, in a first possible design, the second core network element obtains the first SSC mode restriction information based on the capability information of the terminal device, the subscription information of the terminal device, and the network capability information, including:

[0062] The second core network element generates second SSC mode restriction information according to the capability information of the terminal device, the subscription information of the terminal device, and the network capability information;

[0063] The second core network element sends the second SSC mode restriction information to the third core network element, and receives the first SSC mode restriction information returned by the third core network element according to the second SSC mode restriction information.

[0064] Based on the third aspect or the first possible design of the third aspect, in a second possible design, the method also includes: the second core network element sends the first SSC mode restriction information to the terminal device.

[0065] Based on the third aspect, the first possible design of the third aspect, or the second possible design of the third aspect, in a third possible design, after the second core network element sends the first SSC mode restriction information to the terminal device, the method further includes:

[0066] The second core network element receives a second request message from the terminal device, where the second request message includes a session type and a requested SSC mode of the first PDU session;

[0067] After the second core network element determines that the SSC mode requested by the terminal device is not supported based on the first SSC mode restriction information, it returns a second response message to the terminal device, where the second response message is used to indicate that the SSC mode requested by the terminal device is rejected.

[0068] Optionally, the second request message may further include first indication information.

[0069] In the above-mentioned third aspect, the first possible design of the third aspect, the second possible design of the third aspect or the third possible design of the third aspect, the second core network network element is an AMF network element or an SMF network element; the third core network network element is a PCF network element.

[0070] Based on the third aspect, in a fourth possible design, the second core network element obtains the first SSC mode restriction information based on the capability information of the terminal device, the subscription information of the terminal device, and the network capability information, including:

[0071] The second core network element obtains the first SSC mode restriction information based on the capability information of the terminal device, the subscription information of the terminal device, the network capability information and the AF policy, where the AF policy includes an application identifier and an associated SSC mode.

[0072] Based on the third aspect or the fourth possible design of the third aspect, the second core network element is a PCF network element.

[0073] In a fourth aspect, an embodiment of the present application provides a method for determining an SSC mode, the method comprising:

[0074] The second core network network element receives a third request message sent by the terminal device, where the third request message includes the session type of the first PDU session and the requested SSC mode;

[0075] After the second core network element determines that the requested SSC mode is not supported, it returns a third response message to the terminal device, where the third response message is used to indicate that the SSC mode requested by the terminal device is modified to a new SSC mode, and the new SSC mode is the only allowed SSC mode.

[0076] In one possible design, the second core network element is an SMF network element.

[0077] Specifically, the SMF network element can determine whether the requested SSC mode is supported based on the judgment information, where the judgment information includes one or more of the contract information, network capability information, DN authentication information and capability information of the terminal device.

[0078] In a fifth aspect, an embodiment of the present application further provides a terminal device, which can be used to implement the method for determining the SSC mode in the first aspect above. This function can be implemented by software. In one possible design, the terminal device includes: a processing module and a transceiver module;

[0079] Specifically, the processing module is used to determine the requested SSC mode; the transceiver module is used to send a first request message to the first core network network element, and the first request message is used to request to establish a first PDU session, and the first request message includes the session type of the first PDU session and the requested SSC mode.

[0080] In one possible design, the first request message also includes first indication information, and the first indication information is used to indicate that the requested SSC mode is not allowed to be modified.

[0081] In one possible design, before the processing module determines the requested SSC mode, the transceiver module is further configured to:

[0082] Sending capability information of the terminal device to the second core network network element, where the capability information of the terminal device is used to indicate whether the terminal device supports SSC mode 3 of the Non-IP session;

[0083] receiving first SSC mode restriction information from the second core network network element, where the first SSC mode restriction information is determined by capability information of the terminal device, subscription information of the terminal device, and network capability information, the subscription information being used to indicate a session type and an associated SSC mode of a PDU session allowed by the terminal device, and the network capability information being used to indicate whether the network supports SSC mode 3 for a non-IP session;

[0084] The processing module is specifically used for:

[0085] Determine the requested SSC mode according to the session type of the first PDU session and the first SSC mode restriction information.

[0086] In one possible design, the transceiver module is further configured to:

[0087] Receive first SSC mode restriction information from a third core network network element, where the first SSC mode restriction information is determined by capability information of the terminal device, subscription information of the terminal device, network capability information, and AF policy, the capability information of the terminal device being used to indicate whether the terminal device supports SSC mode 3 for non-IP sessions, the subscription information being used to indicate a session type and an associated SSC mode of a PDU session allowed by the terminal device, the network capability information being used to indicate whether the network supports SSC mode 3 for non-IP sessions, and the AF policy including at least one application identifier and an associated SSC mode;

[0088] The processing module is specifically used to determine the requested SSC mode according to the application identifier, the session type of the first PDU session and the first SSC mode restriction information.

[0089] In one possible design, the requested SSC mode is the only SSC mode that satisfies the first SSC mode restriction information.

[0090] In one possible design, the processing module is specifically configured to:

[0091] Use the application-provided SSC mode as the requested SSC mode; or,

[0092] The requested SSC mode is obtained according to the default SSC mode selection policy rule.

[0093] In one possible design, after the transceiver module sends the first request message to the first core network element, it is further configured to:

[0094] Receive a first response message from the first core network element, where the first response message is used to indicate a rejection of establishing the first PDU session.

[0095] In one possible design, the first response message includes reason information (cause code) for refusing to establish the first PDU session, and the cause information is used to indicate at least one of the following: the terminal device does not support the requested SSC mode; the network does not support the requested SSC mode; the data network DN does not support the requested SSC mode; the contract does not support the requested SSC mode.

[0096] In one possible design, the processing module is further configured to:

[0097] If the cause information is used to indicate that the terminal device does not support the requested SSC mode and / or the subscription does not support the requested SSC mode, determining the requested SSC mode as an SSC mode that is not associated with the session type of the first PDU session;

[0098] If the cause information indicates that the network does not support the requested SSC mode, when the accessed public land mobile network PLMN does not change, determine the requested SSC mode as an SSC mode that is not associated with the session type of the first PDU session;

[0099] If the reason information is used to indicate that DN does not support the requested SSC mode, then when the data network name DNN has not changed, the requested SSC mode is determined to be an SSC mode that is not associated with the session type of the first PDU session.

[0100] In one possible design, the first response message also includes the SSC mode allowed by the first PDU session. When the terminal device attempts to request to establish the first PDU session again, the requested SSC mode can be selected based on the SSC mode allowed by the first PDU session.

[0101] In one possible design, after the terminal device receives the first response message from the first core network element, the further step includes:

[0102] The terminal device sends a fourth request message to the first core network network element based on the first response message, where the fourth request message is used to request establishment of the first PDU session, and the fourth request message includes the SSC mode allowed by the first PDU session.

[0103] In the sixth aspect, an embodiment of the present application also provides a core network network element, which can be used to implement the method for determining the SSC mode in the second aspect, third aspect or fourth aspect above. This function can be implemented through software. In one possible design, the core network network element includes: a receiving module, a sending module and a processing module.

[0104] Specifically, taking the method for determining the SSC mode in the above-mentioned second aspect as an example: a receiving module is used to receive a first request message from a terminal device, wherein the first request message includes the session type of the first PDU session and the requested SSC mode; a sending module is used to return a first response message to the terminal device.

[0105] In one possible design, the first request message also includes first indication information, and the first indication information is used to indicate that the requested SSC mode is not allowed to be modified.

[0106] In one possible design, the first response message is used to indicate that the requested SSC mode is rejected.

[0107] In one possible design, the processing module is configured to:

[0108] Obtain judgment information, where the judgment information includes one or more of the contract information, network capability information, DN authentication information, and capability information of the terminal device; the contract information is used to indicate the session type and associated SSC mode of the PDU session allowed by the terminal device, the network capability information is used to indicate whether the network supports SSC mode 3 for Non-IP sessions, the capability information of the terminal device is used to indicate whether the terminal device supports SSC mode 3 for Non-IP sessions, and the DN authentication information is used to indicate the session type and associated SSC mode of the PDU session supported by the DN;

[0109] According to the judgment information, it is determined that the requested SSC mode is not supported.

[0110] In one possible design, the first response message includes reason information for refusing to establish the first PDU session.

[0111] In one possible design:

[0112] If the processing module determines, based on the contract information of the terminal device, that the requested SSC mode is not supported, the cause information indicates that the contract does not support the requested SSC mode;

[0113] If the processing module determines, based on the network capability information, that the requested SSC mode is not supported, the cause information indicates that the network does not support the requested SSC mode;

[0114] If the processing module determines, based on the DN authentication information, that the requested SSC mode is not supported, the cause information indicates that the DN does not support the requested SSC mode;

[0115] If the processing module determines, based on the capability information of the terminal device, that the requested SSC mode is not supported, the cause information indicates that the terminal device does not support the requested SSC mode.

[0116] In one possible design, the first core network network element is an AMF network element or an SMF network element, and the processing module is further configured to:

[0117] Obtain first SSC mode restriction information, where the first SSC mode restriction information is determined by subscription information, network capability information, and capability information of the terminal device;

[0118] According to the first SSC mode restriction information, it is determined that the requested SSC mode is not supported.

[0119] In a seventh aspect, an embodiment of the present application provides an apparatus that implements the functionality of the terminal device described in the fifth aspect. This functionality can be implemented by hardware executing corresponding software. In one possible design, the apparatus includes: a processor, a transceiver, and a memory; the memory is used to store computer-executable instructions; the transceiver is used to enable the apparatus to communicate with other communication entities; the processor is connected to the memory via a bus; when the apparatus is running, the processor executes the computer-executable instructions stored in the memory, so that the apparatus performs the method for determining the SSC mode described in the first aspect.

[0120] Specifically, the processor is used to determine the requested SSC mode; the transceiver is used to send a first request message to the first core network network element, the first request message is used to request to establish a first PDU session, and the first request message includes the session type of the first PDU session and the requested SSC mode.

[0121] In one possible design, the first request message also includes first indication information, and the first indication information is used to indicate that the requested SSC mode is not allowed to be modified.

[0122] In one possible design, before the processor determines the requested SSC mode, the transceiver is further configured to:

[0123] Sending capability information of the terminal device to the second core network network element, where the capability information of the terminal device is used to indicate whether the terminal device supports SSC mode 3 of the Non-IP session;

[0124] receiving first SSC mode restriction information from the second core network network element, where the first SSC mode restriction information is determined by capability information of the terminal device, subscription information of the terminal device, and network capability information, the subscription information being used to indicate a session type and an associated SSC mode of a PDU session allowed by the terminal device, and the network capability information being used to indicate whether the network supports SSC mode 3 for a non-IP session;

[0125] The processor is specifically configured to:

[0126] Determine the requested SSC mode according to the session type of the first PDU session and the first SSC mode restriction information.

[0127] In one possible design, the transceiver is further configured to:

[0128] Receive first SSC mode restriction information from a third core network network element, where the first SSC mode restriction information is determined by capability information of the terminal device, subscription information of the terminal device, network capability information, and AF policy, the capability information of the terminal device being used to indicate whether the terminal device supports SSC mode 3 for non-IP sessions, the subscription information being used to indicate a session type and an associated SSC mode of a PDU session allowed by the terminal device, the network capability information being used to indicate whether the network supports SSC mode 3 for non-IP sessions, and the AF policy including at least one application identifier and an associated SSC mode;

[0129] The processor is specifically used to determine the requested SSC mode according to the application identifier, the session type of the first PDU session and the first SSC mode restriction information.

[0130] In one possible design, the requested SSC mode is the only SSC mode that satisfies the first SSC mode restriction information.

[0131] In one possible design, the processor is specifically configured to:

[0132] Use the application-provided SSC mode as the requested SSC mode; or,

[0133] The requested SSC mode is obtained according to the default SSC mode selection policy rule.

[0134] In one possible design, after sending the first request message to the first core network element, the transceiver is further configured to:

[0135] Receive a first response message from the first core network element, where the first response message is used to indicate a rejection of establishing the first PDU session.

[0136] In one possible design, the first response message includes reason information (cause code) for refusing to establish the first PDU session, and the cause information is used to indicate at least one of the following: the terminal device does not support the requested SSC mode; the network does not support the requested SSC mode; the data network DN does not support the requested SSC mode; the contract does not support the requested SSC mode.

[0137] In one possible design, the processor is further configured to:

[0138] If the cause information is used to indicate that the terminal device does not support the requested SSC mode and / or the subscription does not support the requested SSC mode, determining the requested SSC mode as an SSC mode that is not associated with the session type of the first PDU session;

[0139] If the cause information indicates that the network does not support the requested SSC mode, when the accessed public land mobile network PLMN does not change, determine the requested SSC mode as an SSC mode that is not associated with the session type of the first PDU session;

[0140] If the reason information is used to indicate that DN does not support the requested SSC mode, then when the data network name DNN has not changed, the requested SSC mode is determined to be an SSC mode that is not associated with the session type of the first PDU session.

[0141] In an eighth aspect, an embodiment of the present application provides a device that implements the functions of a core network element in the sixth aspect. This function can be implemented by hardware executing corresponding software. In one possible design, the device includes: a processor, a transceiver, and a memory; the memory is used to store computer-executable instructions; the transceiver is used to enable the device to communicate with other communication entities; the processor is connected to the memory via the bus; when the device is running, the processor executes the computer-executable instructions stored in the memory to cause the device to perform the method for determining the SSC mode in the first aspect.

[0142] Specifically, taking the method for determining the SSC mode in the above-mentioned second aspect as an example: a receiver is used to receive a first request message from a terminal device, wherein the first request message includes the session type of the first PDU session and the requested SSC mode; a transmitter is used to return a first response message to the terminal device.

[0143] In one possible design, the first request message also includes first indication information, and the first indication information is used to indicate that the requested SSC mode is not allowed to be modified.

[0144] In one possible design, the first response message is used to indicate that the requested SSC mode is rejected.

[0145] In one possible design, the processor is configured to:

[0146] Obtain judgment information, where the judgment information includes one or more of the contract information, network capability information, DN authentication information, and capability information of the terminal device; the contract information is used to indicate the session type and associated SSC mode of the PDU session allowed by the terminal device, the network capability information is used to indicate whether the network supports SSC mode 3 for Non-IP sessions, the capability information of the terminal device is used to indicate whether the terminal device supports SSC mode 3 for Non-IP sessions, and the DN authentication information is used to indicate the session type and associated SSC mode of the PDU session supported by the DN;

[0147] According to the judgment information, it is determined that the requested SSC mode is not supported.

[0148] In one possible design, the first response message includes reason information for refusing to establish the first PDU session.

[0149] In one possible design:

[0150] If the processor determines, based on the contract information of the terminal device, that the requested SSC mode is not supported, the cause information indicates that the contract does not support the requested SSC mode;

[0151] If the processor determines, based on the network capability information, that the requested SSC mode is not supported, the cause information indicates that the network does not support the requested SSC mode;

[0152] If the processor determines, based on the DN authentication information, that the requested SSC mode is not supported, the cause information indicates that the DN does not support the requested SSC mode;

[0153] If the processor determines, based on the capability information of the terminal device, that the requested SSC mode is not supported, the cause information indicates that the terminal device does not support the requested SSC mode.

[0154] In one possible design, the first core network network element is an AMF network element or an SMF network element, and the processor is further configured to:

[0155] Obtain first SSC mode restriction information, where the first SSC mode restriction information is determined by subscription information, network capability information, and capability information of the terminal device;

[0156] According to the first SSC mode restriction information, it is determined that the requested SSC mode is not supported.

[0157] Another aspect of an embodiment of the present application provides a communication device, the communication device comprising:

[0158] Memory for storing software programs;

[0159] A processor is used to read the software program in the memory and execute the method for determining the SSC mode described in any one of the first to fourth aspects above.

[0160] Another aspect of an embodiment of the present application provides a computer storage medium, which stores a software program. When the software program is read and executed by one or more processors, it implements the method for determining the SSC mode described in any one of the first to fourth aspects above.

[0161] Another aspect of an embodiment of the present application provides a chip, including a processor, a transceiver component, and optionally, a memory, for executing the method for determining the SSC mode described in any one of the first to fourth aspects above. BRIEF DESCRIPTION OF THE DRAWINGS

[0162] Figure 1 A schematic diagram of a network architecture applicable to an embodiment of the present application;

[0163] Figure 2 A flowchart of selecting an SSC mode for a session is shown;

[0164] Figure 3 Schematic diagram of the flow chart corresponding to the method for determining the SSC mode provided in Example 1 of the present application;

[0165] Figure 4 Schematic diagram of the flow chart corresponding to the method for determining the SSC mode provided in Example 2 of the present application;

[0166] Figure 5 This is a flow chart corresponding to the method for determining the SSC mode provided in Example 3 of the present application;

[0167] Figure 6 Schematic diagram of the flow chart corresponding to the method for determining the SSC mode provided in the fourth embodiment of the present application;

[0168] Figure 7 Schematic diagram of the flow chart corresponding to the method for determining the SSC mode provided in Example 5 of the present application;

[0169] Figure 8 A schematic diagram of the structure of a terminal device provided in an embodiment of the present application;

[0170] Figure 9 A schematic diagram of the structure of a core network element provided in an embodiment of the present application;

[0171] Figure 10 A schematic structural diagram of a communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0172] The present application will be described in detail below with reference to the accompanying drawings.

[0173] Figure 1 This is a schematic diagram of a network architecture applicable to the embodiment of this application. Figure 1 As shown, the network architecture includes: terminal equipment, (radio) access network ((radio) access network, (R)AN) network element, user plane function (UPF) network element, access and mobility management function (AMF) network element, policy control function (PCF) network element, application function (AF) network element, authentication server function (AUSF) network element, unified data management (UDM) network element, and data network (DN) network element.

[0174] Among them, (R)AN) network elements and UPF network elements are logically interconnected through the N3 interface, DN network elements and UPF network elements are logically interconnected through the N6 interface, terminals and AMF network elements are logically interconnected through the N1 interface, (R)AN) network elements and AMF network elements are logically interconnected through the N2 interface, and SMF network elements and UPF network elements are logically interconnected through the N4 interface.

[0175] To facilitate understanding of this application, the main functions of some devices or network elements that may be involved in this application are introduced below.

[0176] A terminal device is a device with wireless transceiver capabilities that can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; on water (such as ships); or in the air (such as aircraft, balloons, and satellites). The terminal can be user equipment (UE), a mobile phone, a tablet computer, a computer with wireless transceiver capabilities, a virtual reality (VR) terminal, an augmented reality (AR) terminal, a wireless terminal in industrial control, a wireless terminal in self-driving, a wireless terminal in remote medical care, a wireless terminal in smart grids, a wireless terminal in transportation safety, a wireless terminal in smart cities, or a wireless terminal in smart homes.

[0177] (R)AN network element: Provides wireless connectivity for terminal devices, ensuring reliable transmission of uplink and downlink data. (R)AN network elements can be gNBs (next generation Node Bs) in 5G systems, base transceiver stations (BTSs) in GSM or CDMA systems, NodeBs (NBs) in WCDMA systems, or evolved NodeBs (eNBs or eNodeBs) in LTE systems.

[0178] The AMF network element is responsible for terminal access management and mobility management. In practice, it includes the mobility management functions of the Mobility Management Entity (MME) in the LTE network framework, and adds access management functions. Its main functions include serving as the termination point for the radio access network control plane, the termination point for non-access signaling, mobility management, lawful interception, and access authorization / authentication.

[0179] SMF network element: Its main functions include session management, terminal Internet Protocol (IP) address allocation and management, selection of manageable user plane functions, termination points of policy control and charging function interfaces, downlink data notification, etc. Its session management functions may include the session management functions of the mobility management network element (MME), or the control plane functions of the serving gateway (SGW) and public data network (PDN) gateway (PDN-GW) in LTE.

[0180] PCF network element: The main function is to perform policy control, similar to the policy and charging rules function (PCRF) network element in LTE. It is mainly responsible for policy authorization, service quality and charging rule generation, and sends the corresponding rules to the UPF network element through the SMF network element to complete the installation of the corresponding policies and rules.

[0181] AF network element: The AF network element can be a third-party application control platform or the operator's own equipment. The AF entity can provide services for multiple application servers. For example, in this application, the AF entity can receive request messages from the application server and provide SSC mode selection strategies for the applications of the relevant terminals (i.e., the services provided by the application server).

[0182] UPF network element: used for packet routing and forwarding, quality of service (QoS) processing of user plane data, etc.

[0183] AUSF network element: Its main functions include user authentication, etc. UDM network element: Used to store mobile user subscription data.

[0184] DN network element: provides services for terminals. DN can include a variety of application servers that can provide different application services for terminals, such as the internet.

[0185] For the above network elements, it should be noted that the network composed of all operator network elements except RAN network elements is called the core network (CN). In the 5G network, CN includes AMF network elements, SMF network elements, UPF network elements, UDM network elements and PCF network elements.

[0186] In this application, the network elements mentioned above can be physical entity network elements or virtual network elements, and are not limited here. Based on the above network architecture, a process for determining the SSC mode is as follows: Figure 2 As shown in the figure, taking Ethernet session as an example, it includes:

[0187] Step 1: The terminal device selects the SSC mode when establishing a session. Specifically, the SSC mode can be selected based on the SSC mode selection policy rule (SSCMSP rule). The SSC mode selection policy rule can be a non-default SSC mode selection policy rule (non-Default SSCMSP rule) that complies with the application or a default SSC mode selection policy rule (Default SSCMSP rule). After selecting the SSC mode, if the terminal device determines that a corresponding SSC mode session can be reused, the session is reused; if not, a new session is created. If there is no non-default SSC mode selection policy rule that complies with the application and there is no default SSC mode selection policy rule, the SSC mode is subsequently determined by the network.

[0188] Step 2: The SMF network element obtains the contract data of the terminal device from the UDM network element. The contract data includes the PDU session type and SSC mode allowed by the terminal device, or the default PDU session type and SSC mode of the terminal device.

[0189] Step 3: The SMF network element determines the SSC mode for the session based on the contract and local configuration. If the terminal device provides the requested SSC mode, the SMF network element checks whether it is allowed. If allowed, the SMF network element returns a supported response message. If not allowed, the SMF network element can modify / reject the session and carry the reason. If the terminal device does not provide an SSC mode, the SMF network element can set the SSC mode of the session to the default SSC mode. If the SMF network element assigns a static IP address to the session, the SSC mode of the session can be set to SSC mode 1.

[0190] Due to the new limitations in 5G networks (Ethernet sessions and unstructured sessions cannot use SSC mode 3) and the two possible types of UEs and 5GCs, they are not taken into account in the process of selecting the SSC mode for the session, which may cause errors in the process of determining the SSC mode.

[0191] Based on this, an embodiment of the present application provides a method for determining an SSC mode, which is used to solve the technical problem that errors may occur in determining the SSC mode in the above method.

[0192] In the following embodiments, the step numbers are only for the convenience of description, and there is no strict execution sequence between the steps.

[0193] Example 1

[0194] Figure 3 This is a flow chart corresponding to the method for determining the SSC mode provided in Example 1 of the present application, as shown in FIG. Figure 3 As shown, the method includes:

[0195] Step 301: The terminal device determines the requested SSC mode.

[0196] In step 302, the terminal device sends a first request message to the first core network element. The first request message is used to request the establishment of a first PDU session. The first request message includes the session type of the first PDU session and the requested SSC mode.

[0197] Here, the first core network network element may be an SMF network element. It should be noted that the terminal device may send a first request message to the first core network network element through other devices, such as an AMF network element. This application does not limit whether the terminal sends the first request message to the first core network network element directly or indirectly. The first request message may also include first indication information, and the first indication information is used to indicate that the requested SSC mode is not allowed to be modified. Furthermore, the terminal device may carry the first indication information in the first request message when it is determined that the requested SSC mode is the only SSC mode supported by the terminal device or under other settings, so as to avoid subsequent network-side network elements from making erroneous decisions, such as modifying the requested SSC mode to other SSC modes not supported by the terminal device.

[0198] There are multiple ways for a terminal device to determine the requested SSC mode. In one possible implementation, the terminal device sends the capability information of the terminal device to the second core network element, and the capability information of the terminal device is used to indicate whether the terminal device supports SSC mode 3 of the Non-IP session; wherein the Non-IP session may include an Ethernet session and / or an unstructured session. The second core network element obtains the first SSC mode restriction information based on the capability information of the terminal device, the subscription information of the terminal device, and one or more of the network capability information, and returns it to the terminal device. The subscription information is used to indicate the session type and associated SSC mode of the PDU session allowed by the terminal device, and the network capability information is used to indicate whether the network supports SSC mode 3 of the Non-IP session. Furthermore, the terminal device can determine the requested SSC mode based on the first SSC mode restriction information and the session type of the first PDU session. In this implementation, the second core network element can be an AMF element.

[0199] In another possible implementation, the terminal device receives first SSC mode restriction information from a third core network element, where the first SSC mode restriction information is determined by the capability information of the terminal device, the subscription information of the terminal device, the network capability information, and the AF policy, where the AF policy includes at least one application identifier and an associated SSC mode; furthermore, the terminal device may determine the requested SSC mode based on the application identifier, the session type of the first PDU session, and the first SSC mode restriction information. In this implementation, the second core network element may be a PCF element.

[0200] Since the above-mentioned first SSC mode restriction information fully considers information from multiple dimensions, the first SSC mode restriction information is more reasonable and effective; in this way, the terminal device, based on the first SSC mode restriction information, if determines that the requested SSC mode is the SSC mode uniquely associated with the session type of the first PDU session, that is, the requested SSC mode is the only SSC mode that satisfies the first SSC mode restriction information, then the first indication information can be used to indicate that the requested SSC mode is not allowed to be modified, thereby avoiding subsequent network-side network elements from making erroneous decisions.

[0201] In the above two implementation methods, the detailed implementation process of the AMF network element or PCF network element obtaining the first SSC mode restriction information can be found in the subsequent specific embodiments.

[0202] In another possible implementation, the terminal device uses the SSC mode provided by the application as the requested SSC mode; or, the terminal device obtains the requested SSC mode according to the default SSC mode selection rule (default SSC mode selection policy rule); or, other methods may be used to determine the requested SSC mode, which is not specifically limited.

[0203] In the embodiment of the present application, the first request message may carry the first indication information in the following situations: (1) the requested SSC mode is the only SSC mode supported by the terminal device; (2) the only SSC mode that satisfies the first SSC mode restriction information; (3) the requested SSC mode is provided by the application; (4) the requested SSC mode is obtained according to the default SSC mode selection rule. It should be noted that the above descriptions are only some of the possible situations in which the first request message carries the first indication information, and are not specifically limited.

[0204] Step 303: The first core network element receives a first request message from the terminal device.

[0205] Step 304: The first core network element returns a first response message to the terminal device.

[0206] Furthermore, the first response message can be used to indicate a refusal to establish the first PDU session. Specifically, the first core network network element obtains judgment information, and the judgment information includes one or more of the contract information, network capability information, DN authentication information, and capability information of the terminal device; wherein, the contract information is used to indicate the session type and associated SSC mode of the PDU session allowed by the terminal device, the network capability information is used to indicate whether the network supports SSC mode 3 of Non-IP session, the capability information of the terminal device is used to indicate whether the terminal device supports SSC mode 3 of Non-IP session, and the DN authentication information is used to indicate the session type and associated SSC mode of the PDU session supported by the data network or to indicate whether the data network supports the SSC mode requested by the terminal device. Furthermore, after the first core network network element determines that the SSC mode requested by the terminal device is not supported based on the judgment information, it returns the first response message to the terminal device.

[0207] Furthermore, the first response message may also include reason information for refusing to establish the first PDU session; the reason information is used to indicate one or more of the following: the terminal device does not support the requested SSC mode; the network does not support the requested SSC mode; the DN does not support the requested SSC mode; the contract does not support the requested SSC mode.

[0208] Specifically, if the first core network network element determines that the requested SSC mode is not supported based on the capability information of the terminal device, the cause information indicates that the terminal device does not support the requested SSC mode. For example, the session type of the first PDU session is a Non-IP session, the requested SSC mode is SSC mode 3, and the capability information of the terminal device indicates that the terminal device does not support SSC mode 3 of the Non-IP session, thereby determining that the requested SSC mode is not supported; if the first core network network element determines that the requested SSC mode is not supported based on the contract information of the terminal device, the cause information indicates that the contract does not support the requested SSC mode; if the first core network network element determines that the requested SSC mode is not supported based on the network capability information, the cause information indicates that the network does not support the requested SSC mode; if the first core network network element determines that the requested SSC mode is not supported based on the DN authentication information, the cause information indicates that the DN does not support the requested SSC mode.

[0209] Furthermore, the first response message may also include the SSC mode allowed by the first PDU session.

[0210] Step 305: The terminal device receives a first response message from the first core network element.

[0211] Furthermore, after receiving the first response message, the terminal device may try the session type or SSC mode of other PDU sessions. Specifically, if the cause information is used to indicate that the terminal device does not support the requested SSC mode and / or the contract does not support the requested SSC mode, the terminal device will determine the requested SSC mode as an SSC mode that is not associated with the session type of the first PDU session, and will no longer select this SSC mode for PDU sessions of the same type in the future. If the cause information is used to indicate that the network does not support the requested SSC mode, the terminal device will determine the requested SSC mode as an SSC mode that is not associated with the session type of the first PDU session when the public land mobile network (PLMN) to which it is connected has not changed. When the PLMN changes, the terminal device may continue to try to select this SSC mode for PDU sessions of the same type. If the reason information is used to indicate that the DN does not support the requested SSC mode, the terminal device will determine the requested SSC mode as an SSC mode that is not associated with the session type of the first PDU session when the data network name (DNN) has not changed. When the DNN changes, the terminal device may continue to try to select this SSC mode for the same type of PDU session.

[0212] If the first response message includes the SSC mode allowed by the first PDU session, the terminal device can send a fourth request message to the first core network network element based on the first response message, and the fourth request message includes the SSC mode allowed by the first PDU session, that is, the terminal device can try to establish the first PDU session again based on the SSC mode allowed by the first PDU session.

[0213] In an embodiment of the present application, since the first request message sent by the terminal device to the first core network network element may carry first indication information, which is used to indicate that the SSC mode requested by the terminal device is not allowed to be modified, thereby avoiding the subsequent network-side network element from making an erroneous decision. Furthermore, the SSC mode requested by the terminal device can be obtained by the terminal device based on the first SSC mode restriction information. Since the first SSC mode restriction information fully considers information of multiple dimensions, the terminal device can determine whether the requested SSC mode is allowed to be modified, and if modification is not allowed, the first indication information is carried in the first request message.

[0214] It should be noted that in the above embodiment, the SMF network element is used to determine whether the SSC mode requested by the terminal device is supported. In other possible embodiments, the AMF network element may also be used to determine whether the SSC mode requested by the terminal device is supported.

[0215] The following describes various possible implementation processes for determining the SSC mode provided in this application in conjunction with specific embodiments.

[0216] Example 2

[0217] Figure 4 The flowchart corresponding to the method for determining the SSC mode provided in the second embodiment of the application is as follows: Figure 4 As shown, the method includes:

[0218] Step 401: The terminal device sends the capability information of the terminal device to the AMF network element.

[0219] Here, the capability information of the terminal device is used to indicate whether the terminal device supports SSC mode 3 of the Non-IP session, wherein the Non-IP session may specifically include an Ethernet session and / or an unstructured session.

[0220] Specifically, the terminal device can send a registration request message (registration request) to the AMF network element, and the registration request message may include the identification of the terminal device and the capability information of the terminal device.

[0221] In step 402, after receiving the capability information of the terminal device, the AMF network element sends a request message (Nudm_SDM_Get / Nudm_SDM_Subscribe) to the UDM network element to request the contract information of the terminal device. Here, the request message includes the identifier of the terminal device.

[0222] Step 403: The UDM network element sends a response message (Nudm_SDM_Get Response / Nudm_SDM_Notification) to the AMF network element.

[0223] Here, the response message may include the contract information of the terminal device, and the contract information is used to indicate the session type and associated SSC mode of the PDU session allowed by the terminal device, or the default session type and associated SSC mode of the PDU session of the terminal device.

[0224] Furthermore, the response message may also include local breakout (LBO) indication information, which is used to indicate whether the terminal device is allowed to use the LBO session in the accessed PLMN network.

[0225] Step 404: After the AMF network element receives the response message returned by the UDM network element, it may send a request message (Npcf_AMPolicyControl_Get) to the PCF network element.

[0226] Here, the request message may include capability information of the terminal device and subscription information of the terminal device, and further, may include LBO indication information.

[0227] In step 405, after receiving the request message sent by the AMF network element, the PCF network element may generate first SSC mode restriction information based on the terminal device's capability information, the terminal device's subscription information, the network capability information, and the AF policy. The network capability information indicates whether the network supports SSC mode 3 for non-IP sessions, and the AF policy includes at least one application identifier and an associated SSC mode.

[0228] Specifically, in one scenario, the PCF network element is an H-PCF network element, and the H-PCF generates the first SSC mode restriction information based on the home network capability information, the terminal device capability information, the terminal device subscription information, and the AF policy. In another scenario, the PCF network element is a V-PCF network element. If the LBO indication information indicates that LBO is allowed, the V-PCF generates the first SSC mode restriction information based on the visited network capability, the terminal device capability information, the terminal device subscription information, and the AF policy; if the LBO indication information does not allow the use of LBO, the V-PCF network element sends information to the H-PCF network element, and the H-PCF generates the first SSC mode restriction information based on the home network capability, the terminal device capability information, the terminal device subscription information, and the AF policy.

[0229] Here, the first SSC mode restriction information is specifically an SSCMSP rule, which may include an application identifier (AppID), a session type of a PDU session, and an associated SSC mode, indicating the session type and associated SSC mode of the PDU session corresponding to the application identifier, as shown in Table 1, which is an example of an SSCMSP rule.

[0230] Table 1: An example of SSCMSP rule

[0231]

[0232] In Table 1, the session types of the PDU sessions corresponding to application 1 include Ethernet sessions and unstructured sessions, wherein the SSC modes associated with the Ethernet sessions include SSC mode 3, and the SSC modes associated with the unstructured sessions include SSC mode 2 and SSC mode 3; the session types of the PDU sessions corresponding to application 2 include Ethernet sessions and IP sessions, wherein the SSC modes associated with the Ethernet sessions include SSC mode 2 and SSC mode 3, and the SSC modes associated with the IP sessions include SSC mode 3; the session types of the PDU sessions corresponding to application n include Ethernet sessions, and the SSC modes associated with the Ethernet sessions include SSC mode 3.

[0233] It should be noted that the PCF network element may update the first SSC mode restriction information, for example, updating it according to a set period, or updating it when it is determined that the first SSC mode restriction information has changed, and there is no specific limitation.

[0234] Step 406: The PCF network element returns a response message (Npcf_AMPolicyControl_GetResponse / Npcf_AMPolicyControl_UpdateNotify) to the AMF network element, where the response message includes the first SSC mode restriction information.

[0235] Step 407: After the AMF network element receives the first SSC mode restriction information sent by the PCF network element, it sends the first SSC mode restriction information to the terminal device.

[0236] Specifically, the AMF network element can send the first SSC mode restriction information to the terminal device through a non-access-stratum (NAS) message.

[0237] Step 408: The terminal device determines the requested SSC mode (ie, the SSC mode available for the first PDU session).

[0238] Specifically, the terminal device can determine the requested SSC mode based on the first SSC mode restriction information, the application identifier and the session type of the first PDU session. In an example, referring to Table 1 above, the terminal device establishes the first PDU session of application 1, and the session type of the first PDU session is an Ethernet session. The terminal device can determine that the requested SSC mode is SSC mode 3.

[0239] Step 409: The terminal device sends a first request message to the AMF network element.

[0240] Step 410: The AMF network element forwards the first request message to the SMF network element.

[0241] Here, the first request message includes the session type of the first PDU session and the requested SSC mode. Furthermore, in the above example, since there is only one SSC mode associated with the session type of the first PDU session, namely SSC mode 3, the first request message may also include first indication information for indicating that the requested SSC mode is not allowed to be modified, thereby effectively preventing the subsequent SMF network element from modifying the requested SSC mode to an SSC mode not supported by other terminal devices.

[0242] In an embodiment of the present application, the AMF network element can also send capability information of the terminal device to the SMF network element.

[0243] In step 411, after receiving the first request message, the SMF network element sends an authentication and authorization request to the Data Network Authentication-Authorisation-Accounting (DN-AAA) server. The authentication and authorization request may include DN authentication and authorization information (i.e., the session type of the first PDU session and the requested SSC mode), and may also include PLMN (i.e., the PLMN where the SMF network element is located).

[0244] In step 412, the SMF network element receives an authentication and authorization response message from the DN-AAA. The authentication and authorization response message includes DN authentication information. The DN authentication information is used to indicate the session type and associated SSC mode of the PDU session supported by the DN (i.e., the SSC mode restriction information of the DN-AAA for the PLMN where the SMF is located), or to indicate whether the DN supports the SSC mode requested by the terminal device. In the embodiment of the present application, the DN authentication information is used to indicate the session type and associated SSC mode of the PDU session supported by the DN as an example for description.

[0245] Step 413: The SMF network element obtains the capability information of the terminal device, the contract information of the terminal device, and the network capability information.

[0246] Here, the network capability information can be pre-configured. The SMF network element can obtain the capability information of the terminal device from the AMF network element, and the details are not repeated here. The SMF network element can obtain the contract information of the terminal device from the UDM network element, and the details are not repeated here.

[0247] Step 414, the SMF network element returns a first response message to the AMF network element.

[0248] Here, the SMF network element can determine whether the requested SSC mode is supported based on the judgment information. If it is determined that the requested SSC mode is not supported, since the first indication information indicates that the requested SSC mode is not allowed to be modified, the SMF network element can return a first response message to the AMF network element to indicate that the SSC mode requested by the terminal device is rejected. The judgment information includes one or more of the capability information of the terminal device, the contract information of the terminal device, the network capability information and the DN authentication information.

[0249] Furthermore, the first response message may include reason information for rejecting the SSC mode requested by the terminal device. Specifically, if the SMF network element determines that the requested SSC mode is not supported based on the contract information of the terminal device, the reason information indicates that the contract does not support the requested SSC mode; if the SMF network element determines that the requested SSC mode is not supported based on the network capability information, the reason information indicates that the network does not support the requested SSC mode; if the SMF network element determines that the requested SSC mode is not supported based on the DN authentication information, the reason information indicates that the DN does not support the requested SSC mode; if the SMF network element determines that the requested SSC mode is not supported based on the capability information of the terminal device, the reason information indicates that the terminal device does not support the requested SSC mode. It should be noted that the reason information can also be used to indicate two or more of the following: the DN does not support the requested SSC mode, the network does not support the requested SSC mode, the terminal device does not support the requested SSC mode, and the contract does not support the requested SSC mode, without specific limitation.

[0250] For example, the session type of the first PDU session is an Ethernet session, and the SSC mode requested by the terminal device is SSC mode 3.

[0251] Scenario 1: The capability information of the terminal device is used to indicate that the terminal device does not support SSC mode 3 of the Non-IP session, while the other three items are supported. In this case, the cause information indicates that the contract does not support the requested SSC mode.

[0252] Scenario 2: The terminal device's capability information is used to indicate that the terminal device supports SSC mode 3 for Non-IP sessions, and the network capability information is used to indicate that the network does not support SSC mode 3 for Non-IP sessions, while the other two items are supported. In this case, the cause information indicates that the network does not support the requested SSC mode.

[0253] Scenario 3: The capability information of the terminal device is used to indicate that the terminal device supports SSC mode 3 of Non-IP sessions, the network capability information is used to indicate that the network supports SSC mode 3 of Non-IP sessions, the contract information of the terminal device is used to indicate that the terminal device allows SSC mode 3 of Non-IP sessions, and the DN authentication information is used to indicate that the DN does not support SSC mode 3 of Non-IP sessions. In this case, the cause information indicates that the DN does not support the requested SSC mode.

[0254] Scenario 4: The capability information of the terminal device is used to indicate that the terminal device does not support SSC mode 3 for Non-IP sessions, and the network capability information is used to indicate that the network does not support SSC mode 3 for Non-IP sessions, while the other two items are supported. In this case, the reason information may indicate that the terminal device does not support the requested SSC mode and the network does not support the requested SSC mode.

[0255] Furthermore, the SMF network element can also determine the SSC mode allowed by the first PDU session, and then return it to the terminal device through a first response message, that is, the first response message can also include the SSC mode allowed by the first PDU session.

[0256] It should be noted that in step 414, if the SMF network element determines that it supports the SSC mode requested by the terminal device, it can return a first response message indicating support for establishing the first PDU session; the embodiment of the present application only specifically describes the rejection situation, and the support situation will not be repeated.

[0257] Step 415: The AMF network element sends the first response message to the terminal device.

[0258] Furthermore, after the terminal receives the first response message, if the first response message is used to indicate a refusal to establish the first PDU session, the terminal device may try other types of PDU sessions or SSC modes. For details, please refer to the description in Example 1, which will not be repeated here. If the first response message is used to indicate support for establishing the first PDU session, the terminal device may execute the subsequent process of establishing the first PDU session, which may be referred to the prior art and will not be repeated here.

[0259] If the first response message includes the SSC mode allowed by the first PDU session, the terminal device can send a fourth request message to the first core network element according to the first response message, and the fourth request message includes the SSC mode allowed by the first PDU session, that is, the terminal device can try to establish the first PDU session again based on the SSC mode allowed by the first PDU session. In this way, it can effectively avoid the terminal device from trying to establish the first PDU session based on other SSC modes that are not allowed, and effectively improve processing efficiency.

[0260] According to the above content, in Example 2, during the registration phase, the PCF network element generates the first SSC mode restriction information based on the capability information of the terminal device, the contract information of the terminal device, the network capability information and the AF policy. Since the PCF network element combines information from multiple dimensions to generate the first SSC mode restriction information, the SSC mode restriction information is more reasonable and effective, which facilitates the terminal device to select an available SC mode based on the first SSC mode restriction information. In the SSC mode determination phase, the SMF network element determines whether the requested SSC mode is supported based on one or more of the capability information of the terminal device, the contract information of the terminal device, the network capability information and the DN authentication information, and gives specific reason information if it is not supported, so that the terminal device can perform corresponding operations based on the reason information.

[0261] Example 3

[0262] Figure 5 This is a flow chart corresponding to the method for determining the SSC mode provided in Example 3 of the present application, as shown in FIG. Figure 5 As shown, the method includes:

[0263] Step 501: The terminal device sends the capability information of the terminal device to the AMF network element.

[0264] Here, the capability information of the terminal device is used to indicate whether the terminal device supports SSC mode 3 of the Non-IP session.

[0265] Step 502: After receiving the capability information of the terminal device, the AMF network element sends a request message to the UDM network element to request the contract information of the terminal device.

[0266] Step 503: The UDM network element sends a response message to the AMF network element.

[0267] Here, the response message may include the contract information of the terminal device, and the contract information is used to indicate the session type and associated SSC mode of the PDU session allowed by the terminal device.

[0268] Furthermore, the response message may also include LBO indication information, which is used to indicate whether the terminal device is allowed to use the LBO session in the accessed PLMN network.

[0269] In step 504, the AMF network element selects the home network or the visited network according to the LBO indication information, and generates the second SSC mode restriction information according to the network capability information of the selected network, the contract information of the terminal device, and the capability information of the terminal device.

[0270] Step 505: The AMF network element sends a request message (Npcf_AMPolicyControl_Get) to the PCF network element, where the request message includes the second SSC mode restriction information.

[0271] Step 506: The PCF network element adjusts the second SSC mode restriction information.

[0272] In one scenario, the PCF network element is a V-PCF network element. If the LBO indication information indicates that LBO is allowed, the V-PCF network element adjusts the second SSC mode restriction information to obtain the first SSC mode restriction information; if the LBO indication information indicates that LBO is not allowed, the V-PCF network element sends information to the H-PCF network element, and the H-PCF network element adjusts the second SSC mode restriction information to obtain the first SSC mode restriction information.

[0273] Specifically, the PCF network element can adjust the second SSC mode restriction information based on the AF policy or local policy. For example, if the second SSC mode restriction information includes an Ethernet session and associated SSC modes (including SSC mode 2 and SSC mode 3), and the AF policy or local policy indicates that the terminal device is not allowed to use SSC mode 3 of the Ethernet session, the PCF network element can adjust the SSC mode associated with the Ethernet session from SSC mode 2 and SSC mode 3 to SSC mode 2, thus deleting SSC mode 3.

[0274] Step 507: The AMF network element receives a response message (Npcf_AMPolicyControl_GetResponse / Npcf_AMPolicyControl_UpdateNotify) sent by the PCF network element, where the response message includes the first SSC mode restriction information.

[0275] Here, the first SSC mode restriction information may include the session type and associated SSC mode of the PDU session available to the terminal device, as shown in Table 2, which is an example of the first SSC mode restriction information.

[0276] Table 2: An example of first SSC pattern restriction information

[0277] Session type of the PDU session Associated SSC mode Ethernet Session SSC Mode 3 Unstructured conversation SSC Mode 2, SSC Mode 3

[0278] In Table 2, the session types of PDU sessions available to the terminal device include Ethernet sessions and unstructured sessions, wherein the SSC modes associated with the Ethernet sessions include SSC mode 3, and the SSC modes associated with the unstructured sessions include SSC mode 2 and SSC mode 3.

[0279] In other possible embodiments, the first SSC mode restriction information may also include the session type of the PDU session and the unassociated SSC mode. For example, in the first SSC mode restriction information, the SSC modes unassociated with the Ethernet session are SSC mode 1 and SSC mode 2, then it can be known that the SSC mode associated with the Ethernet session is SSC mode 3.

[0280] Step 508: The AMF network element sends the first SSC mode restriction information to the terminal device.

[0281] Specifically, the AMF network element can send a registration response message (registration accept) to the terminal device, and the registration response message includes the first SSC mode restriction information.

[0282] Step 509: The terminal device determines the requested SSC mode (ie, the SSC mode available for the first PDU session).

[0283] Specifically, the terminal device can determine the requested SSC mode based on the first SSC mode restriction information. In an example, referring to Table 2 above, the terminal device establishes a first PDU session, and the session type of the first PDU session is an unstructured session. Then, it can be determined that the requested SSC mode is SSC mode 3.

[0284] Step 510: The terminal device sends a second request message to the AMF network element. The second request message includes the session type of the first PDU session and the requested SSC mode.

[0285] In step 511, the AMF network element sends a request message (Nnrf_NFDiscovery) to the NF Repository Function (NRF) network element. The request message includes LBO indication information, requested SSC mode, and session type of the first PDU session.

[0286] Step 512: The NRF network element selects an available SMF network element based on the registration information of the SMF network element and the request message sent by the AMF network element, and sends a response message (Nnrf_NF Discovery Response) to the AMF network element.

[0287] Here, the NRF network element can pre-acquire the registration information of the SMF network element in the network. The registration information of the SMF network element is used to indicate the session type of the PDU session supported by the SMF network element and the associated SSC mode. Furthermore, the NRF network element can select an SMF network element that can support the session type of the first PDU session and the requested SSC mode based on the registration information of the SMF network element.

[0288] Step 513: The AMF network element determines whether the SSC mode requested by the terminal device is supported based on the first SSC mode restriction information and the response message of the NRF network element.

[0289] Here, if the AMF network element determines that the response message returned by NRF is empty, that is, there is no available SMF network element, or the response message indicates that the SMF selection failed, the AMF network element can directly determine to refuse to establish the first PDU session.

[0290] Step 514: The AMF network element returns a second response message to the terminal device, where the response message is used to indicate support or rejection of establishing the first PDU session.

[0291] Here, if the second response message is used to indicate the refusal to establish the first PDU session, the terminal device can try other types of PDU sessions or SSC modes; if the second response message is used to indicate support for establishing the first PDU session, the terminal device can execute the subsequent process of establishing the first PDU session.

[0292] It should be noted that: (1) Steps 511 and 512 are optional steps. In the embodiment of the present application, the AMF network element may also directly determine whether the SSC mode requested by the terminal device is supported based on the first SSC mode restriction information. (2) Since the AMF network element determines whether the SSC mode requested by the terminal device is supported based on the first SSC mode restriction information, when it is determined that the SSC mode requested by the terminal device is not supported, it directly indicates that the first PDU session is rejected without carrying the reason information for rejecting the first PDU session.

[0293] According to the above content, in Example 3, during the registration phase, the AMF network element generates the first SSC mode restriction information based on the capability information of the terminal device, the contract information of the terminal device, and the network capability information. Since the AMF network element combines information of multiple dimensions to generate the first SSC mode restriction information, the SSC mode restriction information is more reasonable and effective, which facilitates the terminal device to select an available SC mode according to the first SSC mode restriction information. Moreover, since the AMF network element does not need to send the contract information and capability information of the terminal device to the PCF network element, some signaling overhead can be saved. In the SSC mode determination stage, the AMF network element determines whether the requested SSC mode is supported based on the first SSC mode restriction information, without forwarding the request message of the terminal device to the SMF network element, thereby effectively improving processing efficiency.

[0294] Example 4

[0295] Figure 6 This is a flow chart corresponding to the method for determining the SSC mode provided in Example 4 of the present application, as shown in FIG. Figure 6 As shown, the method includes:

[0296] Step 601: The terminal device sends the capability information of the terminal device to the AMF network element.

[0297] Step 602: After receiving the capability information of the terminal device, the AMF network element sends a request message to the UDM network element to request the contract information of the terminal device.

[0298] Step 603: The UDM network element sends a response message to the AMF network element. The response message may include the subscription information of the terminal device.

[0299] Step 604: After receiving the response message returned by the UDM network element, the AMF network element may send a request message to the PCF network element.

[0300] Here, the request message may include capability information of the terminal device and contract information of the terminal device.

[0301] Step 605: After the PCF network element receives the request message sent by the AMF network element, it can generate the first SSC mode restriction information based on the capability information of the terminal device, the contract information of the terminal device, the network capability information and the AF policy.

[0302] Step 606: The PCF network element returns a response message to the AMF network element, where the response message includes the first SSC mode restriction information.

[0303] Step 607: After the AMF network element receives the first SSC mode restriction information sent by the PCF network element, it sends the first SSC mode restriction information to the terminal device.

[0304] Step 608: The terminal device determines the requested SSC mode.

[0305] For the above steps, please refer to the description of steps 401 to 408 in the second embodiment.

[0306] In step 609, the terminal device sends a second request message to the AMF network element, where the second request message includes the session type of the first PDU session and the requested SSC mode. Optionally, the second request message may also include the first indication information.

[0307] Step 610: The AMF network element forwards the second request message to the SMF network element.

[0308] Step 611: The SMF network element obtains the first SSC mode restriction information from the PCF network element, and determines whether the SSC mode requested by the terminal device is supported based on the first SSC mode restriction information.

[0309] Step 612: The SMF network element returns a second response message to the AMF network element, where the second response message is used to indicate support or rejection of the SSC mode requested by the terminal device.

[0310] Step 613: The AMF network element returns a second response message to the terminal device.

[0311] Here, if the second response message is used to indicate the refusal to establish the first PDU session, the terminal device can try other types of PDU sessions or SSC modes; if the second response message is used to indicate support for establishing the first PDU session, the terminal device can execute the subsequent process of establishing the first PDU session.

[0312] It should be noted that: (2) In the embodiment of the present application, there is no specific limitation on the manner in which the SMF network element obtains the first SSC mode restriction information from the PCF network element. For example, the SMF network element may send a request message to the PCF network element, and the PCF network element may return the information to the SMF network element. Alternatively, the PCF network element may proactively send the information to the SMF network element. (3) Since the SMF network element determines whether the SSC mode requested by the terminal device is supported based on the first SSC mode restriction information, when it is determined that the SSC mode requested by the terminal device is not supported, it directly indicates that the first PDU session is rejected without carrying the reason information for rejecting the first PDU session.

[0313] According to the above content, in Example 4, during the registration phase, the PCF network element generates the first SSC mode restriction information based on the capability information of the terminal device, the contract information of the terminal device, the network capability information and the AF policy, which is the same as in Example 1. In the SSC mode determination phase, the SMF network element obtains the first SSC mode restriction information from the PCF network element, and determines whether the requested SSC mode is supported based on the first SSC mode restriction information, which can effectively improve processing efficiency. Based on this method of determining the SSC mode, in other possible embodiments, if the AMF network element generates the first SSC mode restriction information based on the capability information of the terminal device, the contract information of the terminal device and the network capability information during the registration phase, the SMF network element can also obtain the first SSC mode restriction information from the AMF network element, and determine whether the requested SSC mode is supported based on the first SSC mode restriction information. There is no specific limitation.

[0314] Example 5

[0315] Figure 7 This is a flow chart corresponding to the method for determining the SSC mode provided in Example 5 of the present application, as shown in FIG. Figure 7 As shown, the method includes:

[0316] Step 701: The terminal device sends the capability information of the terminal device to the AMF network element.

[0317] Step 702: After receiving the capability information of the terminal device, the AMF network element sends a request message to the UDM network element to request the contract information of the terminal device.

[0318] Step 703: The UDM network element sends a response message to the AMF network element. The response message may include the subscription information of the terminal device.

[0319] Step 704: After receiving the response message returned by the UDM network element, the AMF network element may send a request message to the PCF network element.

[0320] Here, the request message may include capability information of the terminal device and contract information of the terminal device.

[0321] Step 705: After the PCF network element receives the request message sent by the AMF network element, it can generate the first SSC mode restriction information based on the capability information of the terminal device, the contract information of the terminal device, the network capability information and the AF policy.

[0322] Step 706: The PCF network element returns a response message to the AMF network element, where the response message includes the first SSC mode restriction information.

[0323] Step 707: After the AMF network element receives the first SSC mode restriction information sent by the PCF network element, it sends the first SSC mode restriction information to the terminal device.

[0324] Step 708: The terminal device determines the requested SSC mode.

[0325] For the above steps, please refer to the description of steps 401 to 408 in the second embodiment.

[0326] Step 709: The terminal device sends a third request message to the AMF network element. The third request message includes the session type of the first PDU session and the requested SSC mode.

[0327] Step 710: The AMF network element forwards the third request message to the SMF network element.

[0328] Step 711, after receiving the third request message, the SMF network element sends an authentication authorization request to DN-AAA. The authentication authorization request may include DN authentication authorization information (i.e., the session type of the first PDU session and the requested SSC mode), and may also include PLMN (i.e., the PLMN where the SMF network element is located).

[0329] Step 712: The SMF network element receives the authentication and authorization response message from DN-AAA, which includes DN authentication information.

[0330] Step 713: The SMF network element obtains the capability information of the terminal device, the contract information of the terminal device, and the network capability information.

[0331] Step 714, the SMF network element returns a third response message to the AMF network element.

[0332] Here, the SMF network element can determine whether the requested SSC mode is supported based on the judgment information. If it is determined that the requested SSC mode is not supported, the SMF network element can modify the requested SSC mode and return a third response message to the AMF network element. The third response message is used to indicate that the SSC mode requested by the terminal device is modified to a new SSC mode, and the new SSC mode is the only allowed SSC mode.

[0333] Specifically, the third response message may include a new SSC mode and second indication information, and the second indication information is used to indicate that the new SSC mode is the only allowed SSC mode.

[0334] Step 715: The AMF network element sends the third response message to the terminal device.

[0335] In this way, after receiving the third response message, the terminal device may no longer try other SSC modes, thereby avoiding the problem that the terminal device tries an unauthorized SSC mode or tries other SSC modes multiple times, resulting in a more complicated processing flow.

[0336] Based on the above-mentioned Example 2, Example 3, Example 4 and Example 5, it can be known that in the registration stage, there are two ways to generate the first SSC mode restriction information: Method 1a, the PCF network element generates the first SSC mode restriction information based on the capability information of the terminal device, the contract information of the terminal device, the network capability information and the AF policy (Example 2, Example 4, Example 5); Method 2a, the AMF network element generates the first SSC mode restriction information based on the capability information of the terminal device, the contract information of the terminal device and the network capability information (Example 3). In the SSC mode determination stage, there are three ways to determine whether the requested SSC mode is supported: Method 1b, the SMF network element determines based on the judgment information (Example 2, Example 5); Method 2b, the AMF network element determines based on the first SSC mode restriction information (Example 3); Method 3b, the SMF network element determines based on the first SSC mode restriction information (Example 4).

[0337] In other possible embodiments, method 2a may be adopted in the registration stage and method 1b may be adopted in the SSC mode determination stage; or, method 2a may be adopted in the registration stage and method 3b may be adopted in the SSC mode determination stage; or other possible combination methods may be adopted, which are not specifically limited in the embodiments of the present application.

[0338] In an embodiment of the present application, in method 1b, if the SMF network element receives a first request message (carrying first indication information), then after determining that the requested SSC mode is not supported, it may return a first response message to indicate that establishment of the first PDU session is rejected; if the SMF network element receives a third request message (not carrying the first indication information), then after determining that the requested SSC mode is not supported, it may modify the requested SSC mode to a new SSC mode, and return a third response message to indicate that the SSC mode requested by the terminal device is modified to a new SSC mode, and the new SSC mode is the only allowed SSC mode. In method 2b and method 3b, after the SMF network element or AMF network element receives the second request message (which may or may not carry the first indication information) and determines that the requested SSC mode is not supported based on the first SSC mode restriction information, it is impossible to accurately modify the requested SSC mode because it cannot directly know the reason for the non-support. Therefore, regardless of whether the second request message carries the first indication information, the SMF network element or AMF network element may not modify the requested SSC mode, but directly return a second response message to indicate the refusal to establish the first PDU session.

[0339] With respect to the above method flow, an embodiment of the present application also provides a terminal device and a core network element. The specific implementation of the terminal device and the core network element can refer to the above method flow.

[0340] Figure 8 This is a schematic diagram of a terminal device provided in an embodiment of the present application, which can be used to implement the above Figures 3 to 6 The corresponding process executed by the terminal device in the embodiment of the present invention comprises: a processing module 801 and a transceiver module 802;

[0341] Specifically, the processing module 801 is used to determine the requested SSC mode; the transceiver module 802 is used to send a first request message to the first core network network element, and the first request message is used to request to establish a first PDU session, and the first request message includes the session type of the first PDU session and the requested SSC mode.

[0342] In one possible design, the first request message may also include first indication information, where the first indication information is used to indicate that the requested SSC mode is not allowed to be modified.

[0343] In one possible design, before the processing module 801 determines the requested SSC mode, the transceiver module 802 is further configured to:

[0344] Sending capability information of the terminal device to the second core network network element, where the capability information of the terminal device is used to indicate whether the terminal device supports SSC mode 3 of the Non-IP session;

[0345] receiving first SSC mode restriction information from the second core network network element, where the first SSC mode restriction information is determined by capability information of the terminal device, subscription information of the terminal device, and network capability information, the subscription information being used to indicate a session type and an associated SSC mode of a PDU session allowed by the terminal device, and the network capability information being used to indicate whether the network supports SSC mode 3 for a non-IP session;

[0346] The processing module 801 is specifically configured to:

[0347] Determine the requested SSC mode according to the session type of the first PDU session and the first SSC mode restriction information.

[0348] In one possible design, the transceiver module 802 is further configured to:

[0349] Receive first SSC mode restriction information from a third core network network element, where the first SSC mode restriction information is determined by capability information of the terminal device, subscription information of the terminal device, network capability information, and AF policy, the capability information of the terminal device being used to indicate whether the terminal device supports SSC mode 3 for non-IP sessions, the subscription information being used to indicate a session type and an associated SSC mode of a PDU session allowed by the terminal device, the network capability information being used to indicate whether the network supports SSC mode 3 for non-IP sessions, and the AF policy including at least one application identifier and an associated SSC mode;

[0350] The processing module 801 is specifically configured to determine the requested SSC mode according to the application identifier, the session type of the first PDU session, and the first SSC mode restriction information.

[0351] In one possible design, the requested SSC mode is the only SSC mode that satisfies the first SSC mode restriction information.

[0352] In one possible design, the processing module 801 is specifically configured to:

[0353] Use the application-provided SSC mode as the requested SSC mode; or,

[0354] The requested SSC mode is obtained according to the default SSC mode selection policy rule.

[0355] In one possible design, after sending the first request message to the first core network element, the transceiver module 802 is further configured to:

[0356] Receive a first response message from the first core network element, where the first response message is used to indicate a rejection of establishing the first PDU session.

[0357] In one possible design, the first response message includes reason information (cause code) for refusing to establish the first PDU session, and the cause information is used to indicate at least one of the following: the terminal device does not support the requested SSC mode; the network does not support the requested SSC mode; the data network DN does not support the requested SSC mode; the contract does not support the requested SSC mode.

[0358] In one possible design, the processing module 801 is further configured to:

[0359] If the cause information is used to indicate that the terminal device does not support the requested SSC mode and / or the subscription does not support the requested SSC mode, determining the requested SSC mode as an SSC mode that is not associated with the session type of the first PDU session;

[0360] If the cause information indicates that the network does not support the requested SSC mode, when the accessed public land mobile network PLMN does not change, determine the requested SSC mode as an SSC mode that is not associated with the session type of the first PDU session;

[0361] If the reason information is used to indicate that DN does not support the requested SSC mode, then when the data network name DNN has not changed, the requested SSC mode is determined to be an SSC mode that is not associated with the session type of the first PDU session.

[0362] In one possible design, the first response message also includes the SSC mode allowed by the first PDU session.

[0363] In one possible design, after the terminal device receives the first response message from the first core network element, the further step includes:

[0364] The terminal device sends a fourth request message to the first core network network element based on the first response message, where the fourth request message is used to request establishment of the first PDU session, and the fourth request message includes the SSC mode allowed by the first PDU session.

[0365] Figure 9 A schematic diagram of the structure of a core network element provided in an embodiment of the present application can be used to implement the above Figures 3 to 6 The corresponding process is executed by the core network element, and the core network element 900 includes: a receiving module 901, a sending module 902 and a processing module 903.

[0366] Specifically, taking the method for determining the SSC mode in the above-mentioned second aspect as an example: the receiving module 901 is used to receive a first request message from the terminal device, and the first request message includes the session type of the first PDU session and the requested SSC mode; the sending module 902 is used to return a first response message to the terminal device.

[0367] In one possible design, the first request message also includes first indication information, and the first indication information is used to indicate that the requested SSC mode is not allowed to be modified.

[0368] In one possible design, the first response message is used to indicate that the requested SSC mode is rejected.

[0369] In one possible design, the processing module 903 is configured to:

[0370] Obtain judgment information, where the judgment information includes one or more of the contract information, network capability information, DN authentication information, and capability information of the terminal device; the contract information is used to indicate the session type and associated SSC mode of the PDU session allowed by the terminal device, the network capability information is used to indicate whether the network supports SSC mode 3 for Non-IP sessions, the capability information of the terminal device is used to indicate whether the terminal device supports SSC mode 3 for Non-IP sessions, and the DN authentication information is used to indicate the session type and associated SSC mode of the PDU session supported by the DN;

[0371] According to the judgment information, it is determined that the requested SSC mode is not supported.

[0372] In one possible design, the first response message includes reason information for refusing to establish the first PDU session.

[0373] In one possible design:

[0374] If the processing module 903 determines, based on the contract information of the terminal device, that the requested SSC mode is not supported, the cause information indicates that the contract does not support the requested SSC mode;

[0375] If the processing module 903 determines, based on the network capability information, that the requested SSC mode is not supported, the cause information indicates that the network does not support the requested SSC mode;

[0376] If the processing module 903 determines, based on the DN authentication information, that the requested SSC mode is not supported, the cause information indicates that the DN does not support the requested SSC mode;

[0377] If the processing module 903 determines, based on the capability information of the terminal device, that the requested SSC mode is not supported, the cause information indicates that the terminal device does not support the requested SSC mode.

[0378] In one possible design, the first response message also includes the SSC mode allowed by the first PDU session.

[0379] In one possible design, the first core network network element is an AMF network element or an SMF network element, and the processing module 903 is further configured to:

[0380] Obtain first SSC mode restriction information, where the first SSC mode restriction information is determined by subscription information, network capability information, and capability information of the terminal device;

[0381] According to the first SSC mode restriction information, it is determined that the requested SSC mode is not supported.

[0382] Figure 10 A schematic diagram of the structure of a communication device provided in an embodiment of the present application, the communication device may be a terminal device or a core network element, such as Figure 10 As shown, the communication device 1000 includes: a transceiver 1001, a processor 1002;

[0383] The transceiver 1001 is used to communicate and interact with other devices.

[0384] The transceiver 1001 may be an RF circuit, a Wi-Fi module, a communication interface, a Bluetooth module, etc.

[0385] The processor 1002 is configured to implement the steps of the above method embodiment.

[0386] Optionally, communication device 1000 may further include a memory 1004 for storing programs, etc. Specifically, the programs may include program code, which may include instructions. Memory 1004 may include RAM or non-volatile memory, such as at least one disk drive. Processor 1002 executes the application programs stored in memory 1004 to implement the aforementioned functions.

[0387] In one possible embodiment, the transceiver 1001, the processor 1002, and the memory 1004 are communicatively connected. For example, the transceiver 1001, the processor 1002, and the memory 1004 may be interconnected via a bus 1003; the bus 1003 may be a PCI bus or an EISA bus. The bus may be divided into an address bus, a data bus, a control bus, and the like. For ease of representation, Figure 10 Only one thick line is used in the diagram, but this does not mean that there is only one bus or one type of bus.

[0388] In the above embodiments, all or part of the embodiments can be implemented by software, hardware, firmware, or any combination thereof. When implemented using software, all or part of the embodiments can be implemented in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of the present invention are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via a wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) method. The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server or data center that includes one or more available media. The available medium can be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive (SSD)).

[0389] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, embodiments of the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, embodiments of the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0390] The embodiments of the present invention are described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0391] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0392] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0393] Obviously, those skilled in the art may make various changes and modifications to the embodiments of the present invention without departing from the spirit and scope of this application. Thus, if these modifications and variations of the embodiments of the present invention fall within the scope of the claims of this application and their equivalents, this application is intended to include such modifications and variations.

Claims

1. A method for determining a service and session continuity SSC mode, characterized in that: The method comprises: The communication device sends a first request message to the first core network network element, where the first request message is used to request establishment of a first PDU session, and the first request message includes a session type of the first PDU session and a requested SSC mode determined by the communication device; The communication device receives a first response message from the first core network element, where the first response message is used to indicate a rejection of establishing the first PDU session; the first response message also includes an SSC mode allowed by the first PDU session; and The communication device requests to re-establish the first PDU session based on the SSC mode allowed by the first PDU session.

2. The method according to claim 1, characterized in that The session type includes an interconnection protocol IP session, an Ethernet session or an unstructured session.

3. The method according to claim 1, characterized in that The session type is an Ethernet session or an unstructured session, and the requested SSC mode included in the first request message is SSC mode 3.

4. The method according to claim 1, wherein The first request message also includes first indication information, where the first indication information is used to indicate that the requested SSC mode is not allowed to be modified.

5. The method according to claim 1, wherein Before the communication device determines the requested SSC mode, the communication device further includes: The communication device receives first SSC mode restriction information from a second core network element, where the first SSC mode restriction information is determined by subscription information of the communication device, where the subscription information is used to indicate a session type and an associated SSC mode of a PDU session allowed by the communication device; The communication device determines a requested SSC mode, including: The communication device determines the requested SSC mode according to the session type of the first PDU session and the first SSC mode restriction information.

6. The method according to claim 1, characterized in that Before the communication device sends the first request message, the communication device further includes: The communication device receives first SSC mode restriction information from a third core network network element, where the first SSC mode restriction information is determined by one or more of capability information of the communication device, subscription information of the communication device, network capability information, and an application function AF policy, the capability information of the communication device being used to indicate whether the communication device supports SSC mode 3 for a Non-IP session, the subscription information being used to indicate a session type and an associated SSC mode of a PDU session allowed by the communication device, the network capability information being used to indicate whether the network supports SSC mode 3 for a Non-IP session, and the AF policy including at least one application identifier and an associated SSC mode; The communication device determines the requested SSC mode based on the application identifier, the session type of the first PDU session and the first SSC mode restriction information.

7. The method according to claim 1, characterized in that The method further comprises: The communication device uses the SSC mode provided by the application as the requested SSC mode; or, The communication device obtains the requested SSC mode according to a default SSC mode selection policy rule.

8. The method according to any one of claims 1 to 7, characterized in that: The first response message also includes cause code for refusing to establish the first PDU session, where the cause code is used for not supporting the requested SSC mode.

9. The method according to any one of claims 1 to 7, characterized in that: The requesting to re-establish the first PDU session based on the SSC mode allowed by the first PDU session includes: A second request message is sent to the first core network element, where the second request message includes the SSC mode allowed by the first PDU session; the second request message is used to request establishment of the first PDU session.

10. A communication device, characterized in that: The communication device comprises: a transceiver module, configured to send a first request message to a first core network network element, where the first request message is used to request establishment of a first PDU session, where the first request message includes a session type of the first PDU session and a requested SSC mode determined by the communication device; The transceiver module is further configured to receive a first response message from the first core network element, where the first response message is used to indicate a rejection of establishing the first PDU session; the first response message also includes an SSC mode allowed by the first PDU session; and The transceiver module is further used to request to re-establish the first PDU session based on the SSC mode allowed by the first PDU session. The communication device according to claim 10 , wherein: The session type includes an interconnection protocol IP session, an Ethernet session or an unstructured session.

12. The communication device according to claim 10, wherein: The session type is an Ethernet session or an unstructured session, and the requested SSC mode included in the first request message is SSC mode 3.

13. The communication device according to claim 10, wherein: The first request message also includes first indication information, where the first indication information is used to indicate that the requested SSC mode is not allowed to be modified.

14. The communication device according to claim 10, characterized in that The transceiver module is also used for: receiving first SSC mode restriction information from a second core network element, where the first SSC mode restriction information is determined by subscription information of the communication device, the subscription information being used to indicate a session type and an associated SSC mode of a PDU session allowed by the communication device; The communication device also includes a processing module, which is used to determine the requested SSC mode according to the session type of the first PDU session and the first SSC mode restriction information.

15. The communication device according to claim 10, wherein: The transceiver module is also used for: receiving first SSC mode restriction information from a third core network network element, where the first SSC mode restriction information is determined by one or more of capability information of the communication device, subscription information of the communication device, network capability information, and an AF policy, the capability information of the communication device being used to indicate whether the communication device supports SSC mode 3 for a non-IP session, the subscription information being used to indicate a session type and an associated SSC mode of a PDU session allowed by the communication device, the network capability information being used to indicate whether the network supports SSC mode 3 for a non-IP session, and the AF policy including at least one application identifier and an associated SSC mode; The communication device also includes a processing module, which is used to determine the requested SSC mode according to the application identifier, the session type of the first PDU session and the first SSC mode restriction information.

16. The communication device according to claim 10, wherein: The communication device further includes a processing module, configured to: Use the SSC mode provided by the application as the SSC mode of the request; or The requested SSC mode is obtained according to a default SSC mode selection policy rule.

17. The communication device according to claim 10, wherein: The first response message also includes cause code information for rejecting the establishment of the first PDU session, where the cause code information is used to indicate that the requested SSC mode is not supported.

18. The communication device according to any one of claims 10 to 17, characterized in that: The transceiver module is further configured to request re-establishment of the first PDU session based on the SSC mode allowed by the first PDU session, specifically: A second request message is sent to the first core network element, where the second request message includes the SSC mode allowed by the first PDU session; the second request message is used to request establishment of the first PDU session.

19. The device according to any one of claims 10 to 17, characterized in that: The apparatus includes a terminal device or a chip in the terminal device.

20. A communication device, characterized in that: comprising a memory and a processor coupled to the memory; The memory stores program instructions, and when the processor executes the program instructions, the device executes the method according to any one of claims 1 to 8.

21. A computer storage medium, wherein instructions are stored in the computer-readable storage medium, and when the computer-readable storage medium is executed on a computer, the computer is caused to execute the method according to any one of claims 1 to 9.

22. A computer program product, characterized in that The method comprises instructions which, when executed on a computer, perform the method according to any one of claims 1 to 9.

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