Communication method and device

Abstract

In the method, an access and mobility management function network element located in a first PLMN determines that a PLMN to which a terminal device belonging to a second PLMN selects to access is a third PLMN, and the third PLMN is an equivalent PLMN of the second PLMN. And the access and mobility management function network element sends a first slice request to a first network slice selection function network element located in the first PLMN, wherein the first slice request comprises the identifier of the second PLMN, the identifier of the third PLMN and the first network slice selection auxiliary information. And the access and mobility management function network element receives a first slice response from the first network slice selection function network element, wherein the first slice response comprises second network slice selection auxiliary information mapped with the first network slice selection auxiliary information. And the access and mobility management function network element obtains a network slice associated with the equivalent attribution PLMN.

Description

Technical Field

[0001] This application relates to the field of communication technology, and in particular to a communication method and apparatus. Background Technology

[0002] To reduce energy consumption, the 3rd Generation Partnership Project (3GPP) proposed indirect network sharing. In indirect network sharing, the hosting operator can share a base station with participating operators; this base station is called a shared base station. In addition to broadcasting the hosting operator's network identifier, the shared base station can also broadcast the identifier of the participating operator's equivalent home public land mobile network (EHPLMN), so that terminals belonging to the participating operator can access the shared base station based on the EHPLMN.

[0003] Figure 1 This is a schematic diagram of an indirect network sharing scenario. For example... Figure 1 As shown, Figure 1 Operator 1 (referred to as OP#1) can share its base station with Operator 2 and Operator 3 (referred to as OP#2 and OP#3, respectively). When terminal #2, belonging to OP#2, accesses the shared base station, it also carries the network slice identifier associated with the EHPLMN of OP#2 to request the shared base station to provide network services to terminal #2 based on the network slice.

[0004] Since the shared base station is managed by OP#1, OP#1 sends the network slice associated with OP#2's EHPLMN to terminal #2. How OP#1 obtains the network slice associated with OP#2's EHPLMN still needs further investigation. Summary of the Invention

[0005] This application provides a communication method and apparatus in which access and mobility management function network elements can obtain the network slice associated with the equivalent PLMN when a terminal device accesses the network based on the equivalent PLMN.

[0006] Firstly, embodiments of this application provide a communication method. This method can be executed by an access and mobility management function (MLM) network element located in a first public terrestrial network (PLMN). Here, the MLM network element can refer to the MLM network element itself, or to a processor, module, chip, or chip system that is equivalent to an MLM network element in implementing the method. In this method, the MLM network element determines that a terminal device belonging to a second PLMN selects to access a third PLMN, where the third PLMN is an equivalent PLMN to the second PLMN. The MLM network element sends a first slice request to a first network slice selection function network element located in the first PLMN. The first slice request includes the identifier of the second PLMN, the identifier of the third PLMN, and first network slice selection auxiliary information, where the first network slice selection auxiliary information is network slice selection auxiliary information associated with the second PLMN. The access and mobility management function network element receives a first slice response from the first network slice selection function network element. The first slice response includes second network slice selection assistance information mapped to the first network slice selection assistance information. The second network slice selection assistance information is network slice selection assistance information associated with the third PLMN.

[0007] As can be seen, through the above method, the access and mobility management function network element can obtain the network slice associated with the equivalent PLMN when the terminal device accesses the network based on the equivalent PLMN. This facilitates the access and mobility management function network element to send the network slice associated with the equivalent PLMN to the terminal device. Furthermore, it facilitates the terminal device to carry the requested network slice associated with the equivalent PLMN when it subsequently accesses the network again based on the equivalent PLMN, so that the access and mobility management function network element can provide network services to the terminal device based on the requested network slice associated with the equivalent PLMN.

[0008] In one optional implementation, the first network slice selection auxiliary information is the network slice selection auxiliary information subscribed by the terminal device.

[0009] In one optional implementation, the access and mobility management function network element further requests the unified data management UDM network element located in the first PLMN to obtain the network slice selection assistance information subscribed by the terminal device. The subscribed network slice selection assistance information includes the network slice selection assistance information associated with the second PLMN, so that the access and mobility management function network element obtains the first network slice selection assistance information from the UDM network element.

[0010] In one optional implementation, the second network slice selection assistance information is at least one of the following: network slice selection assistance information that allows the terminal device to access, and network slice selection assistance information configured by the terminal device.

[0011] In one optional implementation, the first slice request further includes first indication information, which indicates the discovery of a second network slice selection function network element. The second network slice selection function network element is located in a second PLMN, or it is located in a third PLMN. This approach allows the first network slice selection function network element to determine whether the second network slice selection function network element is located in the second or third PLMN based on the first indication information.

[0012] In one optional implementation, the first slice response further includes a mapping relationship between the first network slice selection assistance information and the second network slice selection assistance information. This approach facilitates the access and mobility management function network element in also sending the mapping relationship between the second network slice selection assistance information and the first network slice selection assistance information to the terminal device.

[0013] In one optional implementation, the access and mobility management function (MLM) network element sends at least one of the following to the terminal device: second network slice selection assistance information, and a mapping relationship between the second network slice selection assistance information and the first network slice selection assistance information. This approach facilitates the terminal device carrying the requested network slice selection assistance information associated with the third PLMN when it subsequently accesses the network again based on the third PLMN. This, in turn, allows the MLM network element to provide network services to the terminal device based on the requested network slice selection assistance information associated with the third PLMN.

[0014] In one optional implementation, the second PLMN is the home public land network (HPLMN) of the terminal device, and the third PLMN is the equivalent home public land network (EHPLMN) of the terminal device.

[0015] Secondly, embodiments of this application also provide a communication method, which can be executed by a network slicing selection function network element. This network slicing selection function network element can refer to the network slicing selection function network element itself, or to a processor, module, chip, or chip system that is equivalent to a network slicing selection function network element in implementing the method. In this method, the network slicing selection function network element receives a slicing request. The slicing request includes the identifier of a second PLMN, the identifier of a third PLMN, and first network slicing selection auxiliary information. The second PLMN is the home PLMN of the terminal device, the third PLMN is the equivalent PLMN of the second PLMN, and the first network slicing selection auxiliary information is network slicing selection auxiliary information associated with the second PLMN. The network slicing selection function network element sends a slicing response, which includes second network slicing selection auxiliary information mapped to the first network slicing selection auxiliary information.

[0016] As can be seen, through the above method, the network slice selection function network element can, based on the received slice request, provide feedback on the network slice associated with the PLMN to which the terminal device is equivalent. This facilitates the access and mobility management function network element to send the network slice associated with the PLMN to the terminal device. Consequently, when the terminal device subsequently accesses the network again based on the PLMN to which it is equivalent, it can carry the requested network slice associated with the PLMN to which it is equivalent, so that the access and mobility management function network element can provide network services to the terminal device based on the requested network slice associated with the PLMN to which it is equivalent.

[0017] In one optional implementation, the network slice selection function network element is a first network slice selection function network element located in the first PLMN. In this approach, the slice request received by the first network slice selection function network element can be a first slice request from an access and mobility management function network element located in the first PLMN. Correspondingly, the slice response sent by the first network slice selection function network element can be a first slice response sent to the access and mobility management function network element located in the first PLMN. Therefore, the first network slice selection function network element can, based on the first slice request, feed back the network slice associated with the PLMN of equivalent belonging to the access and mobility management function network element.

[0018] In one optional implementation, when the network slice selection function network element is a first network slice selection function network element, the first network slice selection function network element further performs the following steps: sending a second slice request to a second network slice selection function network element, the second network slice selection function network element being located in a second PLMN or a third PLMN, the second slice request including the identifier of the second PLMN, the identifier of the third PLMN, and the first network slice selection auxiliary information; receiving a second slice response from the second network slice selection function network element, the second slice response including second network slice selection auxiliary information mapped to the first network slice selection auxiliary information, the second network slice selection auxiliary information being network slice selection auxiliary information associated with the third PLMN.

[0019] As can be seen, when the network slice selection function network element is the first network slice selection function network element, the first network slice selection function network element also sends a second slice request to the second network slice selection function network element based on the first slice request, thereby obtaining the second network slice selection auxiliary information mapped to the first network slice selection auxiliary information from the second network slice selection function network element.

[0020] In one optional implementation, the first slice request further includes first indication information, which indicates the discovery of a second network slice selection function network element located in a second or third PLMN. In this approach, the first network slice selection function network element further determines a second network slice selection function network element based on the first indication information, thereby allowing a request to be made to the determined second network slice selection function network element to obtain second network slice selection auxiliary information mapped to the first network slice selection auxiliary information.

[0021] In one optional implementation, the first indication information is used to indicate when a second network slice selection function network element located in the second PLMN is discovered. Based on the first indication information, the first network slice selection function network element determines the second network slice selection function network element, including: sending a discovery request to a network storage function network element, the discovery request including an identifier of the second PLMN; and receiving a discovery response from the network storage function network element, the discovery response including an identifier of the second network slice selection function network element located in the second PLMN. The network storage function network element is located in the second PLMN.

[0022] In another optional implementation, the first indication information is used to indicate when a second network slice selection function network element located in the third PLMN is discovered. Based on the first indication information, the first network slice selection function network element determines the second network slice selection function network element, including: sending a discovery request to a network storage function network element, the discovery request including the identifier of the third PLMN; and receiving a discovery response from the network storage function network element, the discovery response including the identifier of the second network slice selection function network element located in the third PLMN. The network storage function network element is located in the second PLMN.

[0023] As can be seen, the first indication information is used to indicate that when a second network slice selection function network element located in the second PLMN is discovered, the first network slice selection function network element can request the network storage function network element located in the home PLMN to obtain the identifier of the second network slice selection function network element located in the home PLMN; the first indication information is used to indicate that when a second network slice selection function network element located in the third PLMN is discovered, the first network slice selection function network element can request the network storage function network element located in the home PLMN to obtain the identifier of the second network slice selection function network element located in the equivalent home PLMN.

[0024] In another optional implementation, the network slice selection function network element is a second network slice selection function network element located in the second PLMN or the third PLMN. In this mode, the slice request received by the second network slice selection function network element can be a second slice request from a network slice selection function network element located in the first PLMN. Correspondingly, the slice response sent by the second network slice selection function network element can be a second slice response sent to the network slice selection function network element located in the first PLMN. Therefore, the second network slice selection function network element can, based on the second slice request, feed back network slice selection auxiliary information associated with the equivalent PLMN to the network slice selection function network element located in the first PLMN.

[0025] In one optional implementation, the second network slice selection function element further determines second network slice selection auxiliary information that maps to the first network slice selection auxiliary information based on the identifier of the second PLMN and the identifier of the third HPLMN.

[0026] In one optional implementation, the first network slice selection auxiliary information is the network slice selection auxiliary information subscribed by the terminal device.

[0027] In one optional implementation, the second network slice selection assistance information is at least one of the following: network slice selection assistance information that allows the terminal device to access, and network slice selection assistance information configured by the terminal device.

[0028] In one optional implementation, the first slice response and the second slice response further include a mapping relationship between the first network slice selection assistance information and the second network slice selection assistance information. This approach facilitates the transmission of the mapping relationship between the second network slice selection assistance information and the first network slice selection assistance information by the access and mobility management function network element to the terminal device.

[0029] In one optional implementation, the second PLMN is the home public land network (HPLMN) of the terminal device, and the third PLMN is the equivalent home public land network (EHPLMN) of the terminal device.

[0030] Thirdly, embodiments of this application also provide a communication method, which can be executed by a first network slice selection function network element located in a first public terrestrial network (PLMN). Here, the first network slice selection function network element can refer to the network element itself, or to a processor, module, chip, or chip system that is equivalent to the first network slice selection function network element to implement the method. In this method, the first network slice selection function network element receives a first slice request from an access and mobility management function network element located in the first PLMN. The first slice request includes an identifier of a second PLMN, an identifier of a third PLMN, and first network slice selection auxiliary information. The second PLMN is the home PLMN of the terminal device, the third PLMN is the equivalent PLMN of the second PLMN, and the first network slice selection auxiliary information is network slice selection auxiliary information associated with the second PLMN. The first network slice selection function network element sends a second slice request to a second network slice selection function network element located in either the second or third PLMN. The second slice request includes an identifier of the second PLMN, an identifier of the third PLMN, and the first network slice selection auxiliary information. The first network slice selection function network element receives a second slice response from the second network slice selection function network element. The second slice response includes second network slice selection auxiliary information mapped to the first network slice selection auxiliary information. The second network slice selection auxiliary information is network slice selection auxiliary information associated with the third PLMN. The first network slice selection function network element sends a first slice response to the access and mobility management function network element. The first slice response includes the second network slice selection auxiliary information.

[0031] As can be seen, through this method, the first network slice selection function network element can interact with the second network slice selection function network element located in the second or third PLMN based on the first slice request from the access and mobility management function network element, to obtain the network slice associated with the PLMN to which the terminal device is equivalently located. This allows the access and mobility management function network element to feed back the network slice associated with the PLMN to which the terminal device is equivalently located. This facilitates the access and mobility management function network element in sending the network slice associated with the PLMN to the terminal device, and further benefits the terminal device in carrying the requested network slice associated with the PLMN when it subsequently accesses the network again based on the PLMN to which it is equivalently located. This enables the access and mobility management function network element to provide network services to the terminal device based on the requested network slice associated with the PLMN to which it is equivalently located.

[0032] In one optional implementation, the first network slice selection auxiliary information is the network slice selection auxiliary information subscribed by the terminal device.

[0033] In one optional implementation, the second network slice selection assistance information is at least one of the following: network slice selection assistance information that allows the terminal device to access, and network slice selection assistance information configured by the terminal device.

[0034] In one optional implementation, the first slice request further includes first indication information, which indicates the discovery of a second network slice selection function network element located in a second or third PLMN. In this approach, the first network slice selection function network element further determines a second network slice selection function network element based on the first indication information, thereby allowing a request to be made to the determined second network slice selection function network element to obtain second network slice selection auxiliary information mapped to the first network slice selection auxiliary information.

[0035] In one optional implementation, the first indication information is used to indicate when a second network slice selection function network element located in the second PLMN is discovered. Based on the first indication information, the first network slice selection function network element determines the second network slice selection function network element, including: sending a discovery request to a network storage function network element, the discovery request including an identifier of the second PLMN; and receiving a discovery response from the network storage function network element, the discovery response including an identifier of the second network slice selection function network element located in the second PLMN. The network storage function network element is located in the second PLMN.

[0036] In another optional implementation, the first indication information is used to indicate when a second network slice selection function network element located in the third PLMN is discovered. Based on the first indication information, the first network slice selection function network element determines the second network slice selection function network element, including: sending a discovery request to a network storage function network element, the discovery request including the identifier of the third PLMN; and receiving a discovery response from the network storage function network element, the discovery response including the identifier of the second network slice selection function network element located in the third PLMN. The network storage function network element is located in the second PLMN.

[0037] As can be seen, the first indication information is used to indicate that when a second network slice selection function network element located in the second PLMN is discovered, the first network slice selection function network element can request the network storage function network element located in the home PLMN to obtain the identifier of the second network slice selection function network element located in the home PLMN; the first indication information is used to indicate that when a second network slice selection function network element located in the third PLMN is discovered, the first network slice selection function network element can request the network storage function network element located in the home PLMN to obtain the identifier of the second network slice selection function network element located in the equivalent home PLMN.

[0038] In one optional implementation, the second slice response and the first slice response further include a mapping relationship between the first network slice selection assistance information and the second network slice selection assistance information. This approach facilitates the transmission of the mapping relationship between the second network slice selection assistance information and the first network slice selection assistance information by the access and mobility management function network element to the terminal device.

[0039] In one optional implementation, the second PLMN is the home public land network (HPLMN) of the terminal device, and the third PLMN is the equivalent home public land network (EHPLMN) of the terminal device.

[0040] Fourthly, embodiments of this application also provide a communication method, which can be executed by a second network slice selection function network element located in a second PLMN or a third PLMN. Here, the second network slice selection function network element can refer to the network element itself, or to a processor, module, chip, or chip system that is equivalent to the second network slice selection function network element to implement the method. In this method, the second network slice selection function network element receives a second slice request from a first network slice selection function network element located in a first PLMN. The second slice request includes the identifier of the second PLMN, the identifier of the third PLMN, and first network slice selection auxiliary information. The second PLMN is the home PLMN of the terminal device, the third PLMN is the equivalent PLMN of the second PLMN, and the first network slice selection auxiliary information is network slice selection auxiliary information associated with the second PLMN. The second network slice selection function network element sends a second slice response to the first network slice selection function network element. The second slice response includes second network slice selection auxiliary information mapped to the first network slice selection auxiliary information, which is network slice selection auxiliary information associated with the third PLMN.

[0041] As can be seen, through this method, the second network slice selection function network element can, based on the second slice request from the first network slice selection function network element, feed back the network slice associated with the PLMN to which the terminal device is equivalently located. This facilitates the first network slice selection function network element to feed back the network slice associated with the PLMN to which the terminal device is equivalently located, and in turn, facilitates the access and mobility management function network element to send the network slice associated with the PLMN to which the terminal device is equivalently located. This allows the terminal device to carry the requested network slice associated with the PLMN when it subsequently accesses the network again based on the PLMN to which it is equivalently located, so that the access and mobility management function network element can provide network services to the terminal device based on the requested network slice associated with the PLMN to which it is equivalently located.

[0042] In one optional implementation, the first network slice selection auxiliary information is the network slice selection auxiliary information subscribed by the terminal device.

[0043] In one optional implementation, the second network slice selection assistance information is at least one of the following: network slice selection assistance information that allows the terminal device to access, and network slice selection assistance information configured by the terminal device.

[0044] In one optional implementation, the second slice response further includes a mapping relationship between the first network slice selection assistance information and the second network slice selection assistance information. This approach facilitates the use of access and mobility management function network elements to send the mapping relationship between the second and first network slice selection assistance information to the terminal device.

[0045] In one optional implementation, the second PLMN is the home public land network (HPLMN) of the terminal device, and the third PLMN is the equivalent home public land network (EHPLMN) of the terminal device.

[0046] In one optional implementation, the second network slice selection function element further determines second network slice selection auxiliary information that maps to the first network slice selection auxiliary information based on the identifier of the second PLMN and the identifier of the third HPLMN.

[0047] Fifthly, embodiments of this application also provide a communication device. This communication device has some or all of the functions of the access and mobility management function network element described in the first aspect, or it has implemented some or all of the functions of the network slice selection function network element described in the second to fourth aspects. For example, the communication device may possess some or all of the functions of the access and mobility management function network element described in the first aspect of this application, or it may possess the functions of any one of the embodiments of this application implemented individually. The functions can be implemented by hardware or by hardware executing corresponding software. The hardware or software includes one or more units or modules corresponding to the above functions.

[0048] In one possible design, the communication device may include a processing unit and a communication unit. The processing unit is configured to support the communication device in performing the corresponding functions described in the above method. The communication unit is used to support communication between the communication device and other communication devices. The communication device may also include a storage unit coupled to the processing unit and the communication unit, which stores necessary program instructions and data for the communication device.

[0049] In one embodiment, the communication device includes a processing unit and a communication unit, the device being applied to an access and mobility management function network element located in a first public terrestrial network (PLMN).

[0050] The processing unit is used to determine that the PLMN selected by the terminal device belonging to the second PLMN is the third PLMN, and the third PLMN is the equivalent PLMN of the second PLMN.

[0051] The communication unit is used to send a first slice request to a first network slice selection function network element located in the first PLMN. The first slice request includes the identifier of the second PLMN, the identifier of the third PLMN, and first network slice selection auxiliary information. The first network slice selection auxiliary information is network slice selection auxiliary information associated with the second PLMN.

[0052] The communication unit is further configured to receive a first slice response from the first network slice selection function network element, the first slice response including second network slice selection auxiliary information mapped to the first network slice selection auxiliary information, the second network slice selection auxiliary information being network slice selection auxiliary information associated with the third PLMN.

[0053] In addition, other alternative implementations of the communication device in this regard can be found in the relevant content of the first aspect above, and will not be described in detail here.

[0054] In another embodiment, the communication device includes a processing unit and a communication unit, the device being applied to a network element for network slicing selection, and the processing unit being used to process signals / signaling;

[0055] The communication unit is used to receive a slice request, which includes the identifier of a second PLMN, the identifier of a third PLMN, and first network slice selection assistance information. The second PLMN is the PLMN to which the terminal device belongs, the third PLMN is the equivalent PLMN of the second PLMN, and the first network slice selection assistance information is the network slice selection assistance information associated with the second PLMN.

[0056] The communication unit is further configured to send a slice response, the slice response including second network slice selection assistance information mapped to the first network slice selection assistance information, the second network slice selection assistance information being network slice selection assistance information associated with the third PLMN.

[0057] In addition, other alternative implementations of the communication device in this regard can be found in the relevant content of the second aspect above, and will not be described in detail here.

[0058] In another embodiment, the communication device includes a processing unit and a communication unit, the device being applied to a first network slice selection function network element located in a first public terrestrial network (PLMN), the processing unit being used to process signals / signaling;

[0059] The communication unit is configured to receive a first slice request from an access and mobility management function network element located in the first PLMN. The first slice request includes the identifier of the second PLMN, the identifier of the third PLMN, and first network slice selection assistance information. The second PLMN is the home PLMN of the terminal device, the third PLMN is the equivalent PLMN of the second PLMN, and the first network slice selection assistance information is the network slice selection assistance information associated with the second PLMN.

[0060] The communication unit is further configured to send a second slice request to a second network slice selection function network element, the second network slice selection function network element being located in the second PLMN or the third PLMN, the second slice request including the identifier of the second PLMN, the identifier of the third PLMN and the first network slice selection auxiliary information;

[0061] The communication unit is further configured to receive a second slice response from the second network slice selection function network element, the second slice response including second network slice selection auxiliary information mapped to the first network slice selection auxiliary information, the second network slice selection auxiliary information being network slice selection auxiliary information associated with the third PLMN;

[0062] The communication unit is further configured to send a first slice response to the access and mobility management function network element, the first slice response including the second network slice selection assistance information.

[0063] In addition, other alternative implementations of the communication device in this regard can be found in the relevant content of the third aspect above, and will not be described in detail here.

[0064] In another embodiment, the communication device includes a processing unit and a communication unit. The device is applied to a second network slice selection function network element, which is located in a second PLMN or a third PLMN. The processing unit is used to process signals / signaling.

[0065] The communication unit is configured to receive a second slice request from a first network slice selection function network element located in the first PLMN. The second slice request includes the identifier of the second PLMN, the identifier of the third PLMN, and first network slice selection auxiliary information. The second PLMN is the home PLMN of the terminal device, the third PLMN is the equivalent PLMN of the second PLMN, and the first network slice selection auxiliary information is the network slice selection auxiliary information associated with the second PLMN.

[0066] The communication unit is further configured to send a second slice response to the first network slice selection function network element. The second slice response includes second network slice selection auxiliary information mapped to the first network slice selection auxiliary information. The second network slice selection auxiliary information is network slice selection auxiliary information associated with the third PLMN.

[0067] In addition, other alternative implementations of the communication device in this regard can be found in the relevant content of the fourth aspect above, and will not be described in detail here.

[0068] As an example, the communication unit can be a transceiver or a communication interface, the storage unit can be a memory, and the processing unit can be a processor.

[0069] In one embodiment, the communication device includes a processor and a transceiver, the device being applied to an access and mobility management function network element located in a first public terrestrial network (PLMN).

[0070] The processor is configured to determine that the PLMN selected by the terminal device belonging to the second PLMN is the third PLMN, wherein the third PLMN is an equivalent PLMN of the second PLMN.

[0071] The transceiver is used to send a first slice request to a first network slice selection function network element located in the first PLMN. The first slice request includes the identifier of the second PLMN, the identifier of the third PLMN, and first network slice selection auxiliary information. The first network slice selection auxiliary information is network slice selection auxiliary information associated with the second PLMN.

[0072] The transceiver is further configured to receive a first slice response from the first network slice selection function network element, the first slice response including second network slice selection assistance information mapped to the first network slice selection assistance information, the second network slice selection assistance information being network slice selection assistance information associated with the third PLMN.

[0073] In addition, other alternative implementations of the communication device in this regard can be found in the relevant content of the first aspect above, and will not be described in detail here.

[0074] In another embodiment, the communication device includes a processor and a transceiver, the device being applied to a network element for network slicing selection, the processor being used to process signals / signaling;

[0075] The transceiver is used to receive a slice request, which includes the identifier of a second PLMN, the identifier of a third PLMN, and first network slice selection assistance information. The second PLMN is the PLMN to which the terminal device belongs, the third PLMN is the equivalent PLMN of the second PLMN, and the first network slice selection assistance information is the network slice selection assistance information associated with the second PLMN.

[0076] The transceiver is also configured to send a slice response, the slice response including second network slice selection assistance information mapped to the first network slice selection assistance information, the second network slice selection assistance information being network slice selection assistance information associated with the third PLMN.

[0077] In addition, other alternative implementations of the communication device in this regard can be found in the relevant content of the second aspect above, and will not be described in detail here.

[0078] In another embodiment, the communication device includes a processor and a transceiver, the device being applied to a first network slice selection function network element located in a first public terrestrial network (PLMN), the processor being used to process signals / signaling;

[0079] The transceiver is configured to receive a first slice request from an access and mobility management function network element located in the first PLMN. The first slice request includes the identifier of the second PLMN, the identifier of the third PLMN, and first network slice selection assistance information. The second PLMN is the home PLMN of the terminal device, the third PLMN is the equivalent PLMN of the second PLMN, and the first network slice selection assistance information is the network slice selection assistance information associated with the second PLMN.

[0080] The transceiver is further configured to send a second slice request to a second network slice selection function network element, the second network slice selection function network element being located in the second PLMN or the third PLMN, the second slice request including the identifier of the second PLMN, the identifier of the third PLMN and the first network slice selection auxiliary information;

[0081] The transceiver is further configured to receive a second slice response from the second network slice selection function network element, the second slice response including second network slice selection auxiliary information mapped to the first network slice selection auxiliary information, the second network slice selection auxiliary information being network slice selection auxiliary information associated with the third PLMN;

[0082] The transceiver is also configured to send a first slice response to the access and mobility management function network element, the first slice response including the second network slice selection assistance information.

[0083] In addition, other alternative implementations of the communication device in this regard can be found in the relevant content of the third aspect above, and will not be described in detail here.

[0084] In another embodiment, the communication device includes a processor and a transceiver, the device being applied to a second network slice selection function network element, the second network slice selection function network element being located in a second PLMN or a third PLMN, and the processor being used to process signals / signaling;

[0085] The transceiver is configured to receive a second slice request from a first network slice selection function network element located in a first PLMN. The second slice request includes the identifier of the second PLMN, the identifier of the third PLMN, and first network slice selection auxiliary information. The second PLMN is the home PLMN of the terminal device, the third PLMN is the equivalent PLMN of the second PLMN, and the first network slice selection auxiliary information is the network slice selection auxiliary information associated with the second PLMN.

[0086] The transceiver is further configured to send a second slice response to the first network slice selection function network element. The second slice response includes second network slice selection auxiliary information mapped to the first network slice selection auxiliary information. The second network slice selection auxiliary information is network slice selection auxiliary information associated with the third PLMN.

[0087] In addition, other alternative implementations of the communication device in this regard can be found in the relevant content of the fourth aspect above, and will not be described in detail here.

[0088] In another embodiment, the communication device is a chip or chip system. The processing unit may also be a processing circuit or logic circuit; the communication unit may be an input / output interface, interface circuit, output circuit, input circuit, pin, or related circuit on the chip or chip system.

[0089] In implementation, the processor can be used for, but is not limited to, baseband-related processing, and the transceiver can be used for, but is not limited to, radio frequency transceiver. These devices can be disposed on separate chips, or at least partially or entirely on the same chip. For example, the processor can be further divided into analog baseband processors and digital baseband processors. The analog baseband processor can be integrated with the transceiver on the same chip, while the digital baseband processor can be disposed on a separate chip. With the continuous development of integrated circuit technology, more and more devices can be integrated on the same chip. For example, a digital baseband processor can be integrated with multiple application processors (e.g., but not limited to graphics processors, multimedia processors, etc.) on the same chip. Such a chip can be called a system-on-a-chip (SoC). Whether the various devices are disposed independently on different chips or integrated on one or more chips often depends on the needs of the product design. This application does not limit the implementation form of the above-mentioned devices.

[0090] Sixthly, embodiments of this application also provide a processor for executing the various methods described above. During the execution of these methods, the processes related to sending and receiving the aforementioned information can be understood as the processor outputting the aforementioned information and the processor receiving the input information. When outputting the aforementioned information, the processor outputs the information to a transceiver for transmission. After being output by the processor, the information may require further processing before reaching the transceiver. Similarly, when the processor receives the input information, the transceiver receives the information and inputs it to the processor. Furthermore, after the transceiver receives the information, the information may require further processing before being input to the processor.

[0091] Unless otherwise specified, or unless it contradicts its actual function or internal logic in the relevant description, the transmission and reception operations involved by the processor can be more generally understood as processor output and reception, input and other operations, rather than transmission and reception operations directly performed by radio frequency circuits and antennas.

[0092] In implementation, the processor can be a dedicated processor for executing these methods, or it can be a processor that executes computer instructions stored in memory to execute these methods, such as a general-purpose processor. The memory can be a non-transitory memory, such as read-only memory (ROM), which can be integrated with the processor on the same chip or disposed on different chips. This application does not limit the type of memory or the arrangement of the memory and processor.

[0093] In a seventh aspect, embodiments of this application also provide a communication system, which includes a terminal device, an access network device, and a core network device. In another possible design, the system may further include other devices / functional network elements that interact with at least one of the terminal device, the access network device, and the core network device. Specifically, the access and mobility management function network element in the core network device is used to implement the method described in any of the first aspects above, and the network slicing selection function network element in the core network device is used to implement the method described in any of the second to fourth aspects above.

[0094] Eighthly, embodiments of this application provide a computer-readable storage medium for storing instructions that, when executed by a computer, implement the method described in any one of the first to fourth aspects.

[0095] Ninthly, embodiments of this application also provide a computer program product including instructions that, when run on a computer, implement the method described in any one of the first to fourth aspects.

[0096] Tenthly, embodiments of this application provide a chip system including a processor and an interface. The interface is used to acquire programs or instructions, and the processor is used to invoke the programs or instructions to implement or support access and mobility management function network elements in implementing the first aspect, or to implement or support network slicing selection function network elements in implementing the functions involved in any one of the second to fourth aspects. For example, determining or processing at least one of the data and information involved in the above methods. In one possible design, the chip system further includes a memory for storing necessary program instructions and data. The chip system may be composed of chips or may include chips and other discrete devices.

[0097] Eleventhly, embodiments of this application provide a communication device including a processor for executing a computer program or executable instructions stored in a memory, wherein when the computer program or executable instructions are executed, the device performs the methods as described in the various possible implementations of the first to fourth aspects.

[0098] In one possible implementation, the processor and memory are integrated together;

[0099] In another possible implementation, the aforementioned memory is located outside the communication device.

[0100] The beneficial effects of aspects five through eleven can be referenced from the beneficial effects of aspects one through four, and will not be elaborated here. Attached Figure Description

[0101] Figure 1This is a schematic diagram of an indirect network sharing scenario;

[0102] Figure 2 This is a schematic diagram of a system architecture;

[0103] Figure 3 This is a schematic diagram of another system architecture;

[0104] Figure 4 This is a diagram illustrating how network slicing can meet different business needs.

[0105] Figure 5 This is an interactive schematic diagram of a communication method provided in an embodiment of this application;

[0106] Figure 6 This is an interactive schematic diagram of another communication method provided in an embodiment of this application;

[0107] Figure 7 This is an interactive schematic diagram of another communication method provided in the embodiments of this application;

[0108] Figure 8 This is a schematic diagram of the structure of a communication device provided in an embodiment of this application;

[0109] Figure 9 This is a schematic diagram of another communication device provided in an embodiment of this application. Detailed Implementation

[0110] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0111] The embodiments of this application can be applied to fourth-generation (4G) communication systems such as long-term evolution (LTE) systems and fifth-generation (5G) communication systems such as new radio (NR) systems. As communication technologies continue to develop, the technical solutions of the embodiments of this application can also be used in subsequent evolved communication systems, such as sixth-generation (6G) mobile communication technology systems and seventh-generation (7G) mobile communication technology systems.

[0112] Please see Figure 2 , Figure 2 This is a schematic diagram of a system architecture provided in an embodiment of this application. Specifically, Figure 2 This is a schematic diagram of a 5G network architecture based on a service-oriented architecture. Figure 2 The 5G network architecture consists of three parts: terminal equipment, data network (DN), and operator network. For example... Figure 2 As shown, terminal devices can access a wireless network to obtain services from an external network (e.g., DN) or communicate with other devices, such as other terminal devices, through the wireless network. The following sections will discuss these points in detail. Figure 2 The system architecture provides a detailed description of some of the devices / functional network elements involved.

[0113] Terminal devices can include various handheld devices, in-vehicle devices, wearable devices, computing devices, or other processing devices connected to a wireless modem that have wireless communication capabilities. Terminal devices can also be referred to as terminals. Terminal equipment can also refer to user equipment (UE), access terminal, subscriber unit, user agent, cellular phone, smartphone, wireless data card, personal digital assistant (PDA) computer, tablet computer, wireless modem, handset, laptop computer, point of sale (POS) machine, customer-premises equipment (CPE), machine-type communication (MTC) terminal, communication equipment carried on high-altitude aircraft, wearable device, drone, robot, device-to-device (D2D) terminal, vehicle-to-everything (V2X) terminal, virtual reality (VR) terminal equipment, augmented reality (AR) terminal equipment, wireless terminal in industrial control, wireless terminal in self-driving, wireless terminal in remote medical care, and smart grid. This application does not limit the scope of wireless terminals, such as those in grids, transportation safety, smart cities, smart homes, or future communication networks.

[0114] An operator's network may include one or more of the following network elements: Authentication Server Function (AUSF) network elements, Network Exposure Function (NEF) network elements, Policy Control Function (PCF) network elements, Unified Data Management (UDM) network elements, Unified Data Repository (UDR) network elements, Network Repository Function (NRF) network elements, Application Function (AF) network elements, Access and Mobility Management Function (AMF) network elements, Session Management Function (SMF) network elements, Network Slice Selection Function (NSSF) network elements, Radio Access Network (RAN) network elements, and User Plane Function (UPF) network elements. The portion of the operator's network excluding the radio access network can be referred to as the core network portion.

[0115] The RAN (Radio Access Node) is a network composed of multiple 5G-RAN nodes, implementing radio physical layer functions, resource scheduling and radio resource management, radio access control, and mobility management. The 5G-RAN connects to the UPF (User Plane Node) network element via the user plane interface N3 to transmit data from terminal devices; it also establishes a control plane signaling connection with the AMF (Ambient Current Node) network element via the control plane interface N2 to implement functions such as radio access bearer control. RAN nodes can be base stations in 5G networks or base stations, broadband network gateways (BNGs), aggregation switches, or non-3rd generation partnership project (3GPP) access devices in future communication systems.

[0116] Optionally, the RAN node in this application embodiment may include various forms of base stations, such as: macro base stations, micro base stations (also known as small stations), relay stations, access points, equipment that implements base station functions in communication systems evolved after 5G, transmitting and receiving points (TRP), transmitting points (TP), integrated access and backhaul nodes (IAB nodes), mobile switching centers, and equipment that undertakes base station functions in D2D and machine-to-machine (M2M) communications, etc. This application embodiment does not specifically limit these.

[0117] The AMF network element is mainly responsible for UE authentication, UE mobility management, network slice selection, and SMF network element selection. The AMF network element serves as the anchor point for N1 and N2 signaling connections and provides routing for N1 / N2 SM messages to the SMF network element. The AMF network element maintains and manages the UE's status information.

[0118] The SMF network element is primarily responsible for all control plane functions of UE session management, including UPF network element selection, Internet Protocol (IP) address allocation, session quality of service (QoS) management, and obtaining policy and charging control (PCC) policies from the PCF network element.

[0119] UPF network elements serve as the anchor point for protocol data unit (PDU) session connections, and are responsible for filtering data packets from user equipment, transmitting / forwarding data, controlling rates, and generating billing information.

[0120] UDM network elements are mainly responsible for managing user data, such as the management of subscription information, including obtaining subscription information from UDR network elements and providing it to other network elements (such as AMF network elements); generating 3GPP authentication credentials for UEs; and registering and maintaining the network elements currently serving UEs (for example, the AMF represented by AMF ID1 is the UE's current serving AMF).

[0121] The UDR network element is mainly used to store user data, including subscription data called by the UDM network element, policy information called by the PCF network element, structured data used for capability opening, and application data called by the NEF network element.

[0122] NEF (Network Capability Open) network elements are used to connect other internal network elements of the core network with external application servers of the core network, so as to provide network capability information to external application servers, or to provide information from external application servers to core network elements.

[0123] AF network elements interact with core network elements to provide services. For example, they interact with PCF network elements to control service policies, interact with NEF network elements to obtain network capability information or provide application information to the network, and provide data network access point information to PCF network elements to generate routing information for corresponding data services.

[0124] The AUSF network element is used to perform security authentication on the UE when the UE accesses the network.

[0125] The NSSF network element selects a set of slice instances for the UE, determines the AMF set for the UE, and provides network slice selection assistance information (NSSAI).

[0126] PCF network elements are used to generate and manage user, session, and QoS flow processing policies, provide configuration policy information to UEs, and provide policy information for controlling UEs to network control plane network elements (such as AMF and SMF network elements).

[0127] NRF network elements are responsible for network element registration and discovery functions, and maintain network element information, such as the network element's instance identifier, type, public land mobile network (PLMN), slice-related identifier, IP address or fully qualified domain name (FQDN), network element capabilities, supported services, etc.

[0128] In addition, the embodiments of this application can also be applied to, for example... Figure 3 This illustrates a 5G network architecture based on a point-to-point interface. Figure 3 The functional descriptions of the network elements shown can be found in the following references. Figure 2 The functions of the corresponding network elements will not be elaborated here. Figure 3 and Figure 2 The difference is: Figure 3 The interfaces between the various network elements are point-to-point interfaces, rather than service-oriented interfaces.

[0129] The embodiments disclosed in this application will be presented to illustrate various aspects, embodiments, or features of this application in relation to systems including multiple devices, components, modules, etc. It should be understood and appreciated that individual systems may include additional devices, components, modules, etc., and / or may not include all the devices, components, modules, etc. discussed in conjunction with the accompanying drawings. Furthermore, combinations of these approaches may also be used.

[0130] To facilitate understanding of the solutions in the embodiments of this application, the terms that may be involved in the embodiments of this application are explained below.

[0131] 1: Network slicing.

[0132] 5G network slicing technology provides isolated network environments for different application scenarios by creating virtual independent logical networks on the same network infrastructure. This allows different application scenarios to customize network functions and characteristics according to their own needs, effectively guaranteeing the QoS requirements of different services. The goal of 5G network slicing is to organically combine terminal devices, access network resources, core network resources, and network operation and maintenance management systems to provide independently operable and isolated complete networks for different business scenarios or service types.

[0133] For example, Figure 4 This is a diagram illustrating how network slicing can meet different business needs. For example... Figure 4 As shown, critical machine type communication slices (CTC slices) can meet the needs of vehicle-to-everything (V2X) services, massive machine type communication slices (MTC slices) can meet the needs of large-scale meter reading services, and mobile broadband slices (MBB slices) can meet the needs of mobile broadband services. Furthermore, different network slices do not interfere with each other; for example, a sudden surge in meter reading traffic will not affect normal mobile broadband services.

[0134] To meet diverse needs and ensure isolation between network slices, relatively independent management and operation are required for different services, along with tailored business functions and analytical capabilities. Instances of different types of services are deployed on different network slices, and different instances of the same service type can also be deployed on different network slices.

[0135] Multiple network slices can be identified using NSSAI, which is a set of single network slice selection auxiliary information (singleNSSAI, S-NSSAI).

[0136] A network slice can be identified using S-NSSAI, which consists of slice / service type (SST) and slice differentiator (SD). SST describes the slice's characteristics in terms of features and services; SD is optional information used to distinguish different network slices with the same SST characteristics. The following is an explanation of NSSAI:

[0137] 1.1: Configured Network Slice Selection Auxiliary Information (Configured NSSAI).

[0138] The 3GPP protocol specifies that a set of Configured NSSAIs will be configured for each serving public land mobile network (PLMN). Therefore, terminals will store different Configured NSSAIs for different PLMNs. It is clear that the Configured NSSAI stored in the terminal does not distinguish between location areas or access methods; it only corresponds to the PLMN. Furthermore, each Configured NSSAI can contain a maximum of 16 S-NSSAIs.

[0139] Configured NSSAI is assigned (configured) by the operator currently serving the terminal based on operator deployment and user subscription. Therefore, Configured NSSAI is the intersection of the user-subscribed NSSAI and the NSSAI supported by the Serving PLMN. Furthermore, Configured NSSAI is generated by the AMF or NSSF network element and sent to the terminal by the AMF network element via a registration accept message.

[0140] Since a Configured NSSAI is one-to-one with a PLMN, if the PLMN where the terminal is located has not changed and the terminal has stored a Configured NSSAI, the network side will determine not to reassign a Configured NSSAI to the terminal. However, the network side will determine to reassign a Configured NSSAI to the terminal in the following three situations:

[0141] Case 1: The terminal does not have Configured NSSAI.

[0142] Case 1.1: If the terminal's registration message does not contain a requested NSSAI, it indicates that the terminal does not have a configured NSSAI.

[0143] Case 1.2: When the network slicing indication parameter in the terminal's registration message indicates that the Requested NSSAI was generated by the default configured network slicing selection auxiliary information (Default Configured NSSAI), it means that the terminal does not have Configured NSSAI.

[0144] Case 2: Terminal storage Configured NSSAI error.

[0145] If one or more network slices in the Requested NSSAI in the terminal's registration message exceed the current Serving PLMN plan or the network slice range subscribed by the terminal, then the network slices stored locally by the terminal under the Serving PLMN are inconsistent with those on the network side, indicating that the Configured NSSAI stored by the terminal is incorrect.

[0146] Scenario 3: The slice signed by the terminal or the slice supported by the network side changes.

[0147] If the slice information subscribed to by the terminal changes, the network side (such as the AMF network element) will configure the new slice information to the terminal through the configuration update command (CONFIGURATION UPDATE COMMAND), that is, reassign the Configured NSSAI to the terminal.

[0148] 1.2: Default Configured NSSAI.

[0149] Default Configured NSSAI is a default slice set that can be used across different operator networks. It is generally decided jointly by multiple operators and belongs to the standard S-NSSAIs defined by the protocol. Default Configured NSSAI can be pre-configured in the terminal or configured to the terminal by the terminal's home operator's UDM network element through the terminal parameter update process.

[0150] If no Configured NSSAI or Allowed NSSAI is available on the terminal, the terminal can use Default Configured NSSAI to construct Requested NSSAI, and this method applies to all PLMNs.

[0151] 1.3: Allowed NSSAI (Network Slice Selection Auxiliary Information).

[0152] Allowed NSSAI is an NSSAI that is allowed to be used by the terminal device. Allowed NSSAI can contain up to 8 S-NSSAIs.

[0153] Allowed NSSAI is a slice set type that is sent to the terminal by the AMF network element through the Registration Accept message during the registration process. It represents the set of slices available to the terminal within a specified access type (3GPP or Non-3GPP) and a specified area. Therefore, Allowed NSSAI has access type and area attributes; that is, the Allowed NSSAI received by a terminal accessing via 3GPP and non-3GPP may be different. Furthermore, the Allowed NSSAI received by a terminal accessing via 3GPP in area A and area B may also be different. Additionally, Allowed NSSAI is the intersection of the network slice requested by the terminal (i.e., Requested NSSAI), the network slice subscribed by the terminal, and the slices supported by the registered area. When the terminal's registration request message does not carry any slice information, the default S-NSSAIs in the terminal's subscription information can be used. The decision-making process for Allowed NSSAI is completed by the AMF network element or the NSSF network element.

[0154] 1.4: Requested NSSAI.

[0155] A Requested NSSAI is an NSSAI requested by the endpoint in a Registration Request message, indicating the NSSAI the endpoint expects to use subsequently. A Requested NSSAI can contain a maximum of 8 S-NSSAIs.

[0156] Before initiating the registration process, the terminal selects a PLMN and a cell. Once a PLMN is selected, the terminal selects an S-NSSAI from the locally stored Configured-NSSAI and Allowed NSSAI under that PLMN to form a RequestedNSSAI. This Requested NSSAI is then provided to the core network for the core network to select a network slice instance for the terminal. Specifically, the terminal can provide the core network with a set of parameters to assist in selecting a network slice instance.

[0157] 1.5: Subscribed S-NSSAI (Subscribed Single Network Slice Selection Auxiliary Information).

[0158] Subscribed S-NSSAIs are one or more network slices that a terminal subscribes to with its home operator. One or more of these network slices can be designated as the default network slice (default S-NSSAI). A terminal can subscribe to 16 Subscribed S-NSSAIs, and the default S-NSSAIs are 8 of them.

[0159] In a 5G network, NSSAI can be Configured NSSAI, Requested NSSAI, or Allowed NSSAI.

[0160] 2: Public Land Mobile Network (PLMN).

[0161] A PLMN contains a 3-digit mobile country code (MCC) and a 2-digit mobile network code (MNC). For example, if the country code for country #a is 460 and the network code for mobile network #1 is 01, then the PLMN for mobile network #1 in country #a is 46001.

[0162] The PLMN number is an important component of the International Mobile Subscriber Identity (IMSI), consisting of 15 digits between 0 and 9. The first 5 digits of the PLMN number constitute the PLMN number, and the remaining digits are assigned by the network operator as needed.

[0163] In addition, the IMSI is stored in the user's subscriber identity module (SIM) card or universal subscriber identity module (USIM) card.

[0164] 2.1: Home Public Land Mobile Network (HPLMN).

[0165] The PLMN to which IMSI belongs is also called HPLMN, which stands for HPLMN, meaning the PLMN to which the user is registered. In other words, the HPLMN is the PLMN where the user opened their account; all user information and the services available to the user are stored in the homelocation register (HLR) within the HPLMN network. When a user leaves the coverage area of ​​an HPLMN and registers with another PLMN, the user enters a roaming state.

[0166] Furthermore, the MCC and MNC included in the IMSI number on the terminal USIM card are consistent with the MCC and MNC on the HPLMN. For a given user, there is only one PLMN to which they belong.

[0167] 2.2: Equivalent Home Public Land Mobile Network (EHPLMN).

[0168] EHPLMN is the equivalent PLMN of HPLMN, and EHPLMN and HPLMN are of equal status. For example, the operator corresponding to HPLMN may have different number segments. For instance, an operator may have three number segments: 46000, 46002, and 46007. 46000 is the HPLMN of the terminal, while 46002 and 46007 are the EHPLMN of the terminal compared to 46000.

[0169] 2.3: Access to Public Land Mobile Networks (Visited PLMN, VPLMN).

[0170] VPLMN is the PLMN accessed by the terminal. The MCC and MNC on the VPLMN are not exactly the same as the MCC and MNC of the IMSI stored in the SIM card.

[0171] To reduce network construction costs and lower network operating expenses, network sharing has been proposed. Network sharing refers to the sharing of network facilities between two or more operators. In terms of the scope of sharing, network sharing can be divided into sharing sites, base stations, transmission lines, radio network controllers (RNCs), the core network, and even sharing the entire network. The cost savings vary depending on the level of network sharing. Since sites and base stations account for the majority of network construction and maintenance costs, sharing sites and base stations offers the highest potential for cost savings and can be considered the most effective network sharing model.

[0172] One network sharing mode being discussed by 3GPP is indirect network sharing. (The above...) Figure 1 This is a schematic diagram of an indirect network sharing scenario. For example... Figure 1As shown, Operator 1 (referred to as OP#1) can share its base station with Operators 2 and 3 (referred to as OP#2 and OP#3 respectively), and a roaming architecture is used between the primary operator and participating operators. After a terminal of a participating operator accesses the shared base station, all data streams transmitted between the terminal and the core network of the participating operator are transmitted through the core network of the primary operator. Furthermore, other network elements within the primary operator's network, such as the SMF, process the terminal's service requests according to the primary operator's S-NSSAI, while other network elements within the participating operator's network, such as the SMF, process the terminal's service requests according to the participating operator's S-NSSAI.

[0173] The base station shared by the main operator (shared base station) can be called a shared radio access network (shared RAN). This shared base station has an N2 / N3 interface with the core network of OP#1, but no N2 / N3 interface with OP#2 and OP#3. In this way, all data traffic passes through the network of OP#1.

[0174] To ensure that terminals in participating operators can access the shared base station, the shared base station can broadcast the identifier of the equivalent home PLMN of the participating operator. For example, to ensure that terminal #2 in OP#2 can access the shared base station, the shared base station broadcasts the EHPLMN identifier (EHPLMN identity, EHPLMN ID) of OP#2. Therefore, terminal #2, located in the coverage area of ​​the shared base station, cannot find the HPLMN identifier. If it determines that the PLMN ID broadcast by the shared RAN is an EHPLMN ID, it accesses the network based on the EHPLMN ID. In this case, the AMF network element of OP#1 determines that terminal #2 is accessing a different network based on the PLMN selected by terminal #2, while terminal #2 is unaware that the current network is an indirect network sharing. Therefore, terminal #2 will carry the S-NSSAIs associated with EHPLMN and the corresponding slice mapping in the registration process. The slice mapping refers to the mapping relationship between each S-NSSAI associated with EHPLMN and the S-NSSAI associated with HPLMN. The S-NSSAIs associated with EHPLMN carried are the S-NSSAIs requested by terminal #2.

[0175] The shared base station sends the registration request of terminal #2 to the AMF network element of OP#1. The AMF network element of OP#1 determines that terminal #2 has joined the network via indirect network sharing based on the PLMN selected by terminal #2 and the subscription permanent identifier (SUPI) of terminal #2. The SUPI can be the IMSI, which consists of three fields: MCC, MNC, and mobile subscription identification number (MSIN). The MCC and MNC together form the PLMN ID.

[0176] The AMF network element of OP#1 determines the S-NSSAI associated with the VPLMN (i.e., the S-NSSAI in OP#1) that has a mapping relationship with the S-NSSAI associated with the EHPLMN, based on the S-NSSAI and service level agreement (SLA) carried by terminal #2 in the registration request, and provides network services to terminal #2 based on the S-NSSAI associated with the VPLMN.

[0177] However, if terminal #2 instructs the base station to generate a Requested NSSAI for terminal #2 based on the Default configured NSSAI during the registration process, or if terminal #2 does not carry a Requested NSSAI during the registration process, indicating that terminal #2 has not been configured with a Configured NSSAI, then OP #1 will issue a Configured NSSAI for terminal #2. If OP #1 determines that terminal #2 has successfully registered, OP #1 will issue an Allowed NSSAI for terminal #2.

[0178] Since terminal #2 accesses the network based on its EHPLMN ID, both the ConfiguredNSSAI and Allowed NSSAI issued by OP#1 to terminal #2 include the S-NSSAI associated with the EHPLMN. How OP#1 obtains the S-NSSAI associated with terminal #2's EHPLMN from OP#2 still requires further investigation.

[0179] In this embodiment, for ease of explanation, the core network equipment is described using core network elements from a 5G communication system as examples. For instance, the Access and Mobility Management Function (AMF) element in a 5G communication system is used as an example; the Network Slice Selection Function (NSSF) element in a 5G communication system is used as an example; and the Network Storage Function (NRF) element in a 5G communication system is used as an example. In this embodiment, the network slice selection auxiliary information is described using the single network slice selection auxiliary information S-NSSAI as an example.

[0180] It is understood that when the solutions of this application are applied to 6G or future communication systems, the names of the corresponding network function entities may change, and the naming of network slice selection auxiliary information may also change. This application does not limit this.

[0181] In this embodiment of the application, the first PLMN is the home PLMN of the main operator, and also the PLMN for signaling / signaling processing of the terminal device. The terminal device is a terminal device that accesses the shared base station of the main operator based on the EHPLMN.

[0182] In this embodiment of the application, the second PLMN is the home PLMN of the participating operator, which can also be referred to as the PLMN of the terminal equipment in the participating operator. That is, the second PLMN is the HPLMN of the participating operator or the terminal equipment.

[0183] In this embodiment, the third PLMN is the equivalent home PLMN of the participating operator, or the PLMN to which the terminal equipment in the participating operator is equivalently located. That is, the third PLMN is the equivalent PLMN of the second PLMN, or the EHPLMN of the participating operator or the terminal equipment. When a terminal equipment in the participating operator cannot find its home PLMN ID (the identifier of the second PLMN), it can access the network based on the found equivalent home PLMN ID (the identifier of the third PLMN).

[0184] Furthermore, the operator of the second PLMN and the operator of the third PLMN can be the same operator or they can be different operators. For example, both the second PLMN and the third PLMN are... Figure 1The first PLMN is the PLMN of OP#1, and the second PLMN is the HPLMN of OP#1, and the third PLMN is the EHPLMN of OP#1. Alternatively, the second PLMN is the HPLMN of terminal device #1 in OP#1, and the third PLMN is the EHPLMN of terminal device #1. Another example is the second PLMN being the HPLMN of OP#1, the third PLMN being the HPLMN of OP#3, and the third PLMN being the EHPLMN of OP#1. Or, the second PLMN is the HPLMN of terminal device #1 in OP#1, and the third PLMN is the EHPLMN of terminal device #1. The HPLMN and EHPLMN are as described above and will not be repeated here.

[0185] For ease of explanation, the second PLMN will be referred to as the HPLMN of the terminal device, and the third PLMN will be referred to as the HPLMN of the terminal device.

[0186] In this embodiment of the application, the AMF network element is located in the first PLMN, or in other words, the AMF network element is the AMF network element in the first PLMN, or the AMF network element is the AMF network element in operator 1 of the first PLMN.

[0187] In this embodiment, the first NSSF network element is located in the first PLMN, or in other words, the first NSSF network element is an NSSF network element in the first PLMN, or in other words, the first NSSF network element is an NSSF network element in operator 1. Therefore, both the AMF network element and the first NSSF network element are located in the first PLMN, or in other words, the AMF network element and the first NSSF network element are respectively the AMF network element and the NSSF network element in operator 1 of the first PLMN.

[0188] In this embodiment, the second NSSF network element is located in the second PLMN or the third PLMN. Alternatively, the second NSSF network element is an NSSF network element in the second PLMN, or it is an NSSF network element in the third PLMN. Or, the second NSSF network element is an NSSF network element in operator 2 of the second PLMN, or it is an NSSF network element in operator 3 of the third PLMN, where operator 2 and operator 3 may be the same or different.

[0189] This application provides a communication method. Figure 5 This is a schematic diagram illustrating the interaction of this communication method. The method is explained from the perspective of the interaction between the AMF network element, the first NSSF network element, and the second NSSF network element. The communication method includes, but is not limited to, the following steps:

[0190] The S501.AMF network element determines that the terminal equipment belonging to the second PLMN selects the third PLMN as the PLMN to access.

[0191] The third PLMN of the terminal device is an equivalent PLMN of the second PLMN and has the same status as the second PLMN. Therefore, when the terminal device accesses the network, it can access the network based on the ID of the second PLMN or the ID of the third PLMN.

[0192] Specifically, the terminal device stores PLMN selection information. The second PLMN is the terminal device's HPLMN, and the third PLMN is the terminal device's EHPLMN. When the terminal device determines that it cannot select the second PLMN to access the network, it will select the third PLMN to access the network.

[0193] Therefore, the AMF network element can determine the PLMN selected by the terminal device based on the PLMN ID selected when the terminal device accesses the network. When the PLMN ID selected by the terminal device when accessing the network is the ID of the third PLMN (EHPLMN ID), the AMF network element determines that the PLMN selected by the terminal device belonging to the second PLMN is the third PLMN.

[0194] Furthermore, the AMF network element can determine whether a terminal device belongs to the second PLMN based on the terminal device's SUPI. Specifically, the AMF network element determines whether the terminal device belongs to the second PLMN based on the fields included in the terminal device's SUPI.

[0195] During the registration process, the shared RAN sends an N2 message to the AMF network element. This N2 message contains a selected PLMN ID, which represents the PLMN ID selected by the terminal device when accessing the network. Therefore, the AMF network element learns that the PLMN ID selected by the terminal device when accessing the network is the ID of the third PLMN, including by determining the selected PLMN ID from the N2 message received from the shared RAN.

[0196] The AMF network element of the primary operator (the AMF network element located in the first PLMN) will interact with the AMF network element of each of the multiple participating operators in advance to obtain the HPLMN ID and EHPLMN ID of each operator. Thus, the AMF network element of the primary operator can determine that the third PLMN is the EHPLMN of the terminal device based on the HPLMN ID and EHPLMN ID of each of the multiple participating operators, as well as the identifier of the third PLMN selected by the terminal device when accessing the network.

[0197] For example, as shown in Table 1 below, the primary operator is OP#1, and participating operators include OP#2 and OP#3. OP#1's AMF network element 1 interacts with OP#2's AMF network element 2 beforehand to obtain OP#2's HPLMN (i.e., the second PLMN mentioned above) as 46000 and OP#2's EHPLMN (i.e., the third PLMN mentioned above) as 46001. OP#1's AMF network element 1 also interacts with OP#3's AMF network element 3 beforehand to obtain OP#3's HPLMN as 45001 and OP#3's EHPLMN as 45002. Based on the N2 message from the shared base station, AMF network element 1 determines that the PLMN ID selected by terminal device #2 (home PLMN is OP#2, 46000) when accessing the network is 46001. Therefore, AMF network element 1 determines that the PLMN selected by terminal device #2 when accessing the network is the EHPLMN of terminal device #2.

[0198] Table 1

[0199]

[0200]

[0201] Based on the above description of the indirect network sharing scenario, when the AMF network element determines that the terminal device belonging to the second PLMN selects the third PLMN to access, it indicates that the terminal device is under the coverage of the shared RAN and, since it cannot find the ID of the second PLMN (HPLMN ID), it accesses the network based on the ID of the third PLMN (i.e., EHPLMN ID) broadcast by the shared RAN. In other words, it indicates that the terminal device accesses the network through indirect network sharing.

[0202] Therefore, the AMF network element determines that the terminal equipment belonging to the second PLMN selects the third PLMN as the access PLMN. Alternatively, the AMF network element determines that the terminal equipment belonging to the second PLMN accesses the network through indirect network sharing.

[0203] S502. The AMF network element sends a first slice request to the first NSSF network element located in the first PLMN. The first slice request includes the identifier of the second PLMN, the identifier of the third PLMN, and the first S-NSSFAI. Correspondingly, the first NSSF network element receives the first slice request from the AMF network element.

[0204] Here, the first S-NSSAI is the S-NSSAI associated with the second PLMN, that is, the first S-NSSAI is the S-NSSAI associated with the HPLMN. The first S-NSSAI being associated with the second PLMN can be understood as follows: the first S-NSSAI is related to / corresponds to the second PLMN; or it can be understood as the first S-NSSAI being applicable to the second PLMN; or it can be understood as the type of network slice identified by the first S-NSSAI being defined by the second PLMN; or it can be understood as the network slice identified by the first S-NSSAI being a network slice supported by the second PLMN; or it can be understood as the first S-NSSAI being the network slice for which the AMF network element located in the second PLMN can provide network services to the terminal device when the terminal device accesses the second PLMN.

[0205] In one optional implementation, when the AMF network element determines to send a configured S-NSSAI to the terminal device, and / or determines to send an allowed S-NSSAI to the terminal device, it sends a first slice request to the first NSSF network element to request a second S-NSSAI mapped to the first S-NSSAI. This facilitates the AMF network element in sending the configured S-NSSAI and / or allowed NSSAI to the terminal device.

[0206] In one possible approach, the AMF network element determines to send a ConfiguredS-NSSAI to the terminal device when a first condition is met. The first condition includes, but is not limited to, one of the following: the terminal device's registration request carries indication information indicating that the requested NSSAI is determined based on the default configured NSSAI; the terminal device's registration request does not carry a requested NSSAI; or the terminal device's subscribed network slice has been updated.

[0207] The AMF network element determines the terminal device's Requested NSSAI based on the indication information in the registration request. If the Requested NSSAI is not obtained from the registration request, the AMF element determines that the terminal device has not been configured with a Configured S-NSSAI and will therefore send a Configured S-NSSAI to the terminal device. If the network slice subscribed to by the terminal device is updated, the AMF network element will also send a Configured S-NSSAI to the terminal device.

[0208] Specifically, the Configured S-NSSAI sent by the AMF network element to the terminal is the Configured S-NSSAI used by the terminal device in the EHPLMN. In other words, each S-NSSAI contained in the Configured S-NSSAI is an S-NSSAI associated with the EHPLMN. From the terminal device's perspective, the PLMN it accesses is the third PLMN (EHPLMN). Therefore, the AMF network element will issue the Configured S-NSSAI used in the EHPLMN to the terminal device, enabling the terminal device to trigger subsequent registration processes based on the Configured S-NSSAI.

[0209] In one possible approach, when a terminal device successfully registers, the AMF network element determines that it will send an Allowed S-NSSAI to the terminal device. The Allowed S-NSSAI sent by the AMF network element to the terminal is the Allowed S-NSSAI used by the terminal device in the EHPLMN. That is, each S-NSSAI contained in the Allowed S-NSSAI is an S-NSSAI associated with the EHPLMN. Because from the terminal device's perspective, the PLMN it accesses is the third PLMN (EHPLMN), the AMF network element will issue the Allowed S-NSSAI used in the EHPLMN to the terminal device, enabling the terminal device to trigger subsequent session establishment procedures based on the Allowed S-NSSAI.

[0210] In one possible approach, when the first condition mentioned above is met and the terminal device successfully registers, the AMF network element determines that it will send Configured S-NSSAI and Allowed NSSAI to the terminal device, where Configured S-NSSAI and Allowed NSSAI are respectively the Configured S-NSSAI and Allowed S-NSSAI used by the terminal device in EHPLMN.

[0211] Since the terminal equipment belonging to the second PLMN chooses to access the third PLMN (EHPLM), the AMF network element needs to send the Configured S-NSSAI and / or Allowed NSSAI to the terminal equipment, which includes at least one of the following: the S-NSSAI associated with the terminal equipment's EHPLMN, and the mapping relationship between the S-NSSAI associated with the EHPLMN and the S-NSSAI associated with the HPLM. The S-NSSAI associated with the EHPLMN, which is also the S-NSSAI associated with the third PLMN, can be referred to as the second S-NSSAI. Alternatively, the second S-NSSAI is the S-NSSAI applicable to the third PLMN, or it can be understood that the type of network slice identified by the second S-NSSAI is defined by the EHPLMN, or it can be understood that the network slice identified by the second S-NSSAI is a network slice supported by the EHPLMN. The mapping relationship between S-NSSAI associated with EHPLMN and S-NSSAI associated with HPLMN can be understood as the mapping relationship between the identifier of the network slice defined by EHPLMN and the identifier of the network slice defined by HPLMN.

[0212] Therefore, when the AMF network element determines that it will send Configured S-NSSAI and / or Allowed NSSAI to the terminal device, it sends a first slice request to the first NSSF network element to request the acquisition of the second S-NSSAI mapped to the first S-NSSAI. Alternatively, when the AMF network element determines that it will send Configured S-NSSAI and / or Allowed NSSAI to the terminal device, it sends a first slice request to the first NSSF network element, the first slice request being used to request the acquisition of the second S-NSSAI mapped to the first S-NSSAI. Upon receiving the first slice request, the first NSSF network element requests the acquisition of the second S-NSSAI mapped to the first S-NSSAI from the second NSSF network element, and after acquiring the second S-NSSAI mapped to the first S-NSSAI, it feeds back the second S-NSSAI mapped to the first S-NSSAI to the AMF network element. This method facilitates the AMF network element in obtaining the second S-NSSAI mapped to the first S-NSSAI, thereby facilitating the sending of Configured S-NSSAI and / or Allowed S-NSSAI to the terminal device. It is evident that the second S-NSSAI can be Configured S-NSSAI and / or Allowed S-NSSAI.

[0213] Optionally, the first slice request is also used to request the mapping relationship between the first S-NSSAI and the second S-NSSAI. The mapping relationship between the first S-NSSAI and the second S-NSSAI can be called slice mapping. Therefore, the first slice request can also be understood as requesting the second S-NSSAI mapped to the first S-NSSAI, as well as the slice mapping.

[0214] Additionally, the first slice request includes the identifier of the second PLMN, the identifier of the third PLMN, and the first S-NSSAI. The identifier of the second PLMN, the identifier of the third PLMN, and the first S-NSSAI are used by the second NSSF network element located in the second or third PLMN to determine the second S-NSSAI mapped to the first S-NSSAI. Optionally, the identifier of the second PLMN is also used by the first NSSF network element to determine the second NSSF network element located in the second PLMN, or the identifier of the third PLMN is also used by the first NSSF network element to determine the second NSSF network element located in the third PLMN.

[0215] Furthermore, the identifier of the second PLMN is also the identifier of the PLMN composed of the MCC and MNC in the SUPI of the terminal device. Therefore, the first slice request including the identifier of the second PLMN, the identifier of the third PLMN, and the first S-NSSAI can be replaced with: the first slice request including the identifier of the PLMN in the SUPI, the identifier of the third PLMN, and the first S-NSSAI.

[0216] In one optional implementation, before sending the first slice request to the first NSSF network element, the AMF network element also requests the NSSAI (Subscribed NSSAI) of the terminal device from the UDM network element located in the second PLMN. In one possible approach, the AMF network element's request to the UDM network element in the second PLMN to obtain the NSSAI of the terminal device includes: sending a first request message to the UDM network element in the second PLMN, the first request message being used to request the NSSAI of the terminal device, the first request message including the identifier of the terminal device; and receiving a first response message from the UDM network element, the first response message including the NSSAI of the terminal device. Correspondingly, the UDM network element in the second PLMN further performs the following steps: receiving the first request message from the AMF network element in the first PLMN; and sending a first response message to the AMF network element.

[0217] The Subscribed NSSAI of the terminal device includes the S-NSSAI associated with the HPLMN of the terminal device, that is, it includes the first S-NSSAI. Therefore, the first S-NSSAI is the S-NSSAI subscribed to by the terminal device. The first S-NSSAI is the identifier of the network slice defined by the HPLMN.

[0218] For example, the Subscribed NSSAI of the terminal device includes S-NSSAI#1, S-NSSAI#2 and S-NSSAI#3, all of which are S-NSSAIs associated with the HPLMN of the terminal device.

[0219] As can be seen, the UDM network element located in the PLMN (second PLMN) to which the terminal device belongs stores the Subscribed NSSAI of the terminal device, and the Subscribed NSSAI includes the S-NSSAI associated with the HPLMN of the terminal device. Then, the AMF network element can also request the Subscribed NSSAI from the UDM network element to obtain the S-NSSAI associated with the HPLMN (i.e., the first S-NSSAI). Then, by carrying the first slice request of the S-NSSAI, it can request the second S-NSSAI mapped to the first S-NSSAI from the first NSS network element.

[0220] In one optional implementation, the first slice request further includes first indication information, which indicates the discovery of a second NSSF network element. The second NSSF network element is located in a second PLMN, or in a third PLMN. That is, the first indication information indicates the discovery of a second NSSF network element located in a second PLMN, or in a third PLMN.

[0221] An AMF network element can use various methods to indicate the discovery of a second NSSF network element located in a second or third PLMN via a first indication message, and this application embodiment does not limit this method. In one possible method, the first indication message can be in the form of bits to indicate the discovery of a second NSSF network element located in a second or third PLMN. For example, when the first indication message is bit 1, it is used to indicate the discovery of a second NSSF network element located in a second PLMN; when the first indication message is bit 0, it is used to indicate the discovery of a second NSSF network element located in a third PLMN.

[0222] In another possible approach, the first indication information may include the identifier of the second PLMN or the identifier of the third PLMN, thereby indicating the discovery of a second NSSF network element located in the second PLMN or the third PLMN through the PLMN identifier carried in the first indication information. Specifically, when the first indication information includes the identifier of the second PLMN, it is used to indicate the discovery of a second NSSF network element located in the second PLMN; when the first indication information includes the identifier of the third PLMN, it is used to indicate the discovery of a second NSSF network element located in the third PLMN.

[0223] Although the first slice request sent by the AMF network element to the first NSSF network element includes the identifiers of the second PLMN and the third PLMN, the first NSSF network element still does not know which NSSF network element to request the second S-NSSAI that the AMF network element requests and which is mapped to the first S-NSSAI. Therefore, the first instruction information can instruct the first NSSF network element to discover the second NSSF network element located in the second PLMN by including the identifier of the second PLMN, and then request the second NSSF network element located in the second PLMN to obtain the second S-NSSAI mapped to the first S-NSSAI requested by the AMF network element. For example, the identifier of the second PLMN can be included in a specific information element in the first instruction information. Alternatively, the first instruction information can instruct the first NSSF network element to discover the second NSSF network element located in the third PLMN by including the identifier of the third PLMN, and then request the second NSSF network element located in the third PLMN to obtain the second S-NSSAI mapped to the first S-NSSAI requested by the AMF network element. For example, the identifier of the third PLMN can be included in a specific information element in the first instruction information.

[0224] Therefore, the first NSSF network element can discover the second NSSF network element based on the PLMN identifier included in the first indication information, and request the second NSSF network element to obtain the second S-NSSAI mapped to the first S-NSSAI. However, the first S-NSSAI is associated with the second PLMN, and the second S-NSSAI is associated with the third PLMN. Therefore, in order for the second NSSF network element to return the second S-NSSAI mapped to the first S-NSSAI, the second NSSF network element needs to obtain the identifiers of the second and third PLMNs.

[0225] Therefore, when the AMF network element informs the first NSSF network element via the first indication information to request the discovery of the second NSSF network element located in the second PLMN, the first slice request sent by the AMF network element also includes the identifier of the third PLMN. This ensures that when the first NSSF network element requests the second NSSF network element to obtain the second S-NSSAI mapped to the first S-NSSAI, it can send the identifiers of the second PLMN and the third PLMN to the second NSSF network element. This guarantees that the second NSSF network element can respond with the second S-NSSAI mapped to the first S-NSSAI based on the identifiers of the second PLMN and the third PLMN. In other words, to ensure that the second NSSF network element can respond with the second S-NSSAI mapped to the first S-NSSAI requested by the AMF network element, the first indication information includes the identifier of the second PLMN, and the first slice request also carries the identifier of the third PLMN.

[0226] Similarly, when the AMF network element informs the first NSSF network element via the first indication information that it requests to discover the second NSSF network element located in the third PLMN, the first slice request sent by the AMF network element also includes the identifier of the second PLMN. This ensures that when the first NSSF network element requests the second NSSF network element to obtain the second S-NSSAI mapped to the first S-NSSAI, it can send the identifiers of the second PLMN and the third PLMN to the second NSSF network element. This guarantees that the second NSSF network element can respond with the second S-NSSAI mapped to the first S-NSSAI based on the identifiers of the second PLMN and the third PLMN. In other words, to ensure that the second NSSF network element can respond with the second S-NSSAI mapped to the first S-NSSAI requested by the AMF network element, the first indication information includes the identifier of the third PLMN, and the first slice request also carries the identifier of the second PLMN.

[0227] The first NSSF network element is located within the first PLMN. Since the first NSSF network element does not store / has been configured with a mapping relationship between the S-NSSAI associated with the HPLMN and the S-NSSAI associated with the EHPLMN of the terminal device, it cannot store a mapping relationship between the first S-NSSAI and the second S-NSSAI, and therefore cannot independently find the second S-NSSAI mapped to the first S-NSSAI. However, the NSSF network element located within the HPLMN or EHPLMN of the terminal device stores or has been configured with a mapping relationship between the S-NSSAI associated with the HPLMN and the S-NSSAI associated with the EHPLMN. Therefore, in order for the first NSSF network element to obtain the second S-NSSAI mapped to the first S-NSSAI, the first NSSF network element requests the second S-NSSAI mapped to the first S-NSSAI from the NSSF network element located within the HPLMN or EHPLMN. Therefore, the first slice request sent by the AMF network element to the first NSSF network element also includes first indication information, instructing the first NSSF network element to discover a second NSSF network element located in the second PLMN or the third PLMN. This approach facilitates the first NSSF network element in determining the second NSSF network element based on the first indication information, and further facilitates the first NSSF network element in requesting the second NSSF network element to obtain the second S-NSSAI mapped to the first S-NSSA.

[0228] In another optional implementation, the first slice request does not include the first indication information. In this method, the AMF network element does not instruct the first NSSF network element to request which NSSF network element to discover. Instead, the first NSSF network element determines the second NSSF network element used to request the acquisition of the second S-NSSAI. For example, the first NSSF network element determines the second NSSF network element based on the identifier of the second PLMN in the first slice request, or it determines the second NSSF network element based on the identifier of the third PLMN in the first slice request.

[0229] In one optional implementation, the first slice request does not have any additional request meaning, such as requesting to obtain a second S-NSSAI mapped to the first S-NSSAI. In this approach, the first slice request further includes second indication information, which indicates a request to obtain the second S-NSSAI mapped to the first S-NSSAI. Optionally, the second indication information may also indicate a request to obtain the mapping relationship between the first S-NSSAI and the second S-NSSAI.

[0230] S503. The first NSSF network element sends a second slice request to the second NSSF network element. The second slice request includes the identifier of the second PLMN, the identifier of the third PLMN, and the first S-NSSAI. Correspondingly, the second NSSF network element receives the second slice request from the first NSSF network element.

[0231] In S503, the second NSSF network element is located in the second PLMN or in the third PLMN.

[0232] In one possible approach, the first slice request and the second slice request are the same message. For example, after receiving the first slice request, the first NSSF network element does not process the first slice request but directly sends it to the second NSSF network element, thus making the first slice request and the second slice request the same message.

[0233] In another possible approach, the first slice request and the second slice request are different messages. The second slice request is a slice request processed by the first NSSF network element after processing the first slice request. For example, the first slice request includes the aforementioned first indication information. The first NSSF network element removes the first indication information from the first slice request to obtain the second slice request. That is, the second slice request includes the identifier of the second PLMN, the identifier of the third PLMN, and the first S-NSSAI, but does not include the first indication information. Therefore, the first slice request and the second slice request are different messages.

[0234] In one optional implementation, when the first slice request further includes first indication information, the first NSSF network element further determines a second NSSF network element located in the second PLMN or the third PLMN based on the first indication information.

[0235] In one possible approach, the first indication information is used to indicate that when a second NSSF network element located in the second PLMN is discovered, the first NSSF network element determines the second NSSF network element based on the first indication information, including: sending a discovery request to an NRF network element, the discovery request including the identifier of the second PLMN; and receiving a discovery response from the NRF network element, the discovery response including the identifier of the second NSSF network element located in the second PLMN. The NRF network element is located in the first PLMN.

[0236] In another possible approach, the first indication information is used to indicate that when a second NSSF network element located in the third PLMN is discovered, the first NSSF network element determines the second NSSF network element based on the first indication information, including: sending a discovery request to an NRF network element, the discovery request including the identifier of the third PLMN; and receiving a discovery response from an NRF network element, the discovery response including the identifier of the second NSSF network element located in the third PLMN.

[0237] It can be seen that the first indication information is used to indicate that when a second NSSF network element located in the second PLMN is discovered, the first NSSF network element can request the NRF network element located in the second PLMN to obtain the second NSSF network element located in the second PLMN; the first indication information is used to indicate that when a second NSSF network element located in the third PLMN is discovered, the first NSSF network element can request the NRF network element located in the second PLMN to obtain the second NSSF network element located in the third PLMN.

[0238] In another optional implementation, when the first slice request does not include the first indication information, the first NSSF network element determines the second NSSF network element itself. In one possible approach, the first NSSF network element requests the discovery of the second NSSF network element located in the second PLMN from the NRF network element located in the second PLMN based on the identifier of the second PLMN in the first slice request. In another possible approach, the first NSSF network element requests the discovery of the second NSSF network element located in the third PLMN from the NRF network element located in the second PLMN based on the identifier of the third PLMN in the first slice request. The implementation method where the first NSSF network element requests the discovery of the second NSSF network element located in the second PLMN or the third PLMN from the NRF network element located in the second PLMN can be found in the above implementation method where the first NSSF network element requests the discovery of the second NSSF network element located in the second PLMN or the third PLMN based on the first indication information, and will not be repeated here.

[0239] If the second NSSF network element is located in the second or third PLMN, then the second NSSF network element stores / is configured with the mapping relationship between the S-NSSAI associated with the HPLMN of the terminal device and the S-NSSAI associated with the EHPLMN of the terminal device. Therefore, after the first NSSF network element receives the first slice request from the AMF network element, it can send a second slice request to the second NSSF network element to request the second S-NSSAI mapped to the first S-NSSAI.

[0240] S504. The second NSSF network element sends a second slice response to the first NSSF network element, the second slice response including a second S-NSSAI mapped to the first S-NSSAI. Correspondingly, the first NSSF network element receives the second slice response from the second NSSF network element.

[0241] In one optional implementation, the second NSSF network element further determines the second S-NSSAI mapped to the first S-NSSAI based on the identifier of the second PLMN and the identifier of the third HPLMMN. The second NSSF network element stores the mapping relationship between the S-NSSAI associated with the HPLMMN and the S-NSSAI associated with the EHPLMN of the terminal device. Therefore, after receiving the second slice request, the second NSSF network element can determine the S-NSSAI associated with the EHPLMN mapped to the S-NSSAI associated with the HPLMMN based on the HPLM ID and EHPLMN ID in the second slice request, i.e., determine the second S-NSSAI. Furthermore, the second NSSF network element can feed back the second S-NSSAI to the first NSSF network element through the second slice response.

[0242] For example, the identifier of the second PLMN included in the first slice request and the second slice request is HPLMN#a, the identifier of the third PLMN is EHPLMN#a, and the first S-NSSAI includes S-NSSAI#1, S-NSSAI#2, and S-NSSAI#3. The mapping relationship between the S-NSSAI associated with HPLMN#a and the S-NSSAI associated with EHPLMN#a stored in the second NSSF network element includes: S-NSSAI#1 is mapped to S-NSSAI#a, S-NSSAI#2 is mapped to S-NSSAI#b, and S-NSSAI#3 is mapped to S-NSSAI#c. Then, the S-NSSAIs mapped to S-NSSAI#1, S-NSSAI#2, and S-NSSAI#3 are S-NSSAI#a, S-NSSAI#b, and S-NSSAI#c, respectively, and the second slice response includes S-NSSAI#a, S-NSSAI#b, and S-NSSAI#c.

[0243] In one optional implementation, when the second NSSF network element determines the second slice response, it determines the order of the multiple second S-NSSAIs in the second slice response according to the order in which they are mapped to the first S-NSSAIs included in the second slice request. Thus, the multiple second S-NSSAIs included in the second slice response are mapped one-to-one with the multiple first S-NSSAIs in the second slice request. This method is advantageous because when the AMF network element obtains the multiple second S-NSSAIs in the second slice response, it assumes that each of the multiple second S-NSSAIs is mapped one-to-one with the multiple first S-NSSAIs in the first slice request, thereby obtaining the mapping relationship between the second S-NSSAIs and the first S-NSSAIs.

[0244] For example, the first slice request and the second slice request include first S-NSSAIs of S-NSSAI#1, S-NSSAI#2, and S-NSSAI#3. The second NSSF network element determines that the second slice response includes multiple second S-NSSAIs of S-NSSAI#a, S-NSSAI#b, and S-NSSAI#c. S-NSSAI#a is mapped to S-NSSAI#1, S-NSSAI#b is mapped to S-NSSAI#2, and S-NSSAI#c is mapped to S-NSSAI#3. Therefore, after obtaining S-NSSAI#a, S-NSSAI#b, and S-NSSAI#c, the AMF can determine that the S-NSSAI mapped to S-NSSAI#a is S-NSSAI#1, the S-NSSAI mapped to S-NSSAI#b is S-NSSAI#2, and the S-NSSAI mapped to S-NSSAI#c is S-NSSAI#3.

[0245] In one optional implementation, the second slice response further includes the mapping relationship between the first S-NSSAI and the second S-NSSAI. That is, the second slice response includes the second S-NSSAI and the mapping relationship between the second S-NSSAI and the first S-NSSAI. This approach allows AMF network elements to obtain not only the second S-NSSAI mapped to the first S-NSSAI, but also the mapping relationship between the second S-NSSAI and the first S-NSSAI. This, in turn, allows AMF network elements to send the S-NSSAI associated with the EHPLMN, and the mapping relationship between the S-NSSAI associated with the EHPLMN and the S-NSSAI associated with the HPLMN, when sending ConfiguredNSSAI and / or Allowed NSSAI to the terminal device.

[0246] For example, the identifier of the second PLMN included in the first slice request and the second slice request is HPLMN#a, the identifier of the third PLMN is EHPLMN#a, and the first S-NSSAI includes S-NSSAI#1, S-NSSAI#2, and S-NSSAI#3. The mapping relationship between the S-NSSAI associated with HPLMN#a and the S-NSSAI associated with EHPLMN#a stored in the second NSSF network element includes: S-NSSAI#1 mapped to S-NSSAI#a, S-NSSAI#2 mapped to S-NSSAI#b, and S-NSSAI#3 mapped to S-NSSAI#c. Then, the second slice response includes S-NSSAI#a, S-NSSAI#b, and S-NSSAI#c, as well as the mapping between S-NSSAI#a and S-NSSAI#1, S-NSSAI#b and S-NSSAI#2, and S-NSSAI#c and S-NSSAI#3. Alternatively, the second slice response includes S-NSSAI#a, S-NSSAI#b, and S-NSSAI#c, as well as S-NSSAI#1 mapped to S-NSSAI#a, S-NSSAI#2 mapped to S-NSSAI#b, and S-NSSAI#3 mapped to S-NSSAI#c.

[0247] It is evident that after receiving a second slice request from the first NSSF network element, the second NSSF network element can, through the second slice response, feed back the second S-NSSAI mapped to the first S-NSSAI to the first NSSF network element. This method is beneficial for the first NSSF network element to feed back the second S-NSSAI mapped to the first S-NSSAI to the AMF network element. Alternatively, after receiving a second slice request from the first NSSF network element, the second NSSF network element can, through the second slice response, feed back the second S-NSSAI mapped to the first S-NSSAI, as well as the mapping relationship between the first S-NSSAI and the second S-NSSAI, to the first NSSF network element. This method is beneficial for the first NSSF network element to feed back the second S-NSSAI mapped to the first S-NSSAI, as well as the mapping relationship between the first S-NSSAI and the second S-NSSAI, to the AMF network element.

[0248] S505. The first NSSF network element sends a first slice response to the AMF network element, the first slice response including the second S-NSSFAI. Correspondingly, the AMF network element receives the first slice response from the first NSSF network element.

[0249] It can be seen that after the first NSSF network element receives the second slice response, it feeds back the second S-NSSAI to the AMF network element through the first slice response, so that the AMF network element obtains the second S-NSSAI mapped to the first S-NSSAI.

[0250] In one possible scenario, the first slice response and the second slice response are the same message. For example, after receiving the second slice response from the second NSSF network element, the first NSSF network element does not process the second slice response and directly sends it to the AMF network element, thus making the first slice response and the second slice response the same message.

[0251] In another possible approach, the first slice response and the second slice response are different messages. For example, the first slice response is a slice response after the first NSSF network element processes the second slice response.

[0252] In one optional implementation, when the second slice response further includes the mapping relationship between the first S-NSSAI and the second S-NSSAI, the first slice response further includes the mapping relationship between the first S-NSSAI and the second S-NSSAI, so that the AMF network element also obtains the mapping relationship between the first S-NSSAI and the second S-NSSAI.

[0253] Additionally, when the second S-NSSAI is a Configured S-NSSAI, the second slice response and the first slice response include each second S-NSSAI in the Configured NSSA, or the second slice response and the first slice response include each second S-NSSAI in the Configured NSSA and the mapping between each second S-NSSAI and the first S-NSSAI (i.e., the mapping relationship between each second S-NSSAI and the first S-NSSAI).

[0254] When the second S-NSSAI is an Allowed S-NSSAI, the second slice response and the first slice response include each second S-NSSAI in the Allowed NSSA, or the second slice response and the first slice response include each second S-NSSAI in the Allowed NSSA and the mapping between each second S-NSSAI and the first S-NSSAI (i.e., the mapping relationship between each second S-NSSAI and the first S-NSSAI).

[0255] In one optional implementation, after receiving the first slice response, the AMF network element further sends at least one of the following to the terminal device: a second S-NSSAI, and a mapping relationship between the second S-NSSAI and the first S-NSSAI. Alternatively, when the second S-NSSAI is a Configured S-NSSAI, after receiving the first slice response, the AMF network element further sends at least one of the following to the terminal device: the S-NSSAI associated with each EHPLMN in the Configured S-NSSAI, and a mapping between the S-NSSAI associated with each EHPLMN and the S-NSSAI associated with the HPLMN. Alternatively, when the second S-NSSAI is an Allowed S-NSSAI, after receiving the first slice response, the AMF network element further sends at least one of the following to the terminal device: the S-NSSAI associated with each EHPLMN in the Allowed S-NSSAI, and a mapping between the S-NSSAI associated with each EHPLMN and the S-NSSAI associated with the HPLMN.

[0256] As described above, if the AMF network element determines to send Configured NSSAI and / or Allowed NSSAI to the terminal device, and the terminal device belonging to the second PLMN selects the third PLMN as the access PLMN, then the AMF network element sends at least one of the following to the terminal device: the second S-NSSAI, and the mapping relationship between the second S-NSSAI and the first S-NSSAI. Therefore, when the terminal device subsequently accesses the network again based on the identifier (EHPLMN ID) of the third PLMN, it can select the requested S-NSSAI from Configured NSSAI and / or Allowed NSSAI based on service requirements (such as QoS requirements), and thus can include the Requested NSSAI in the registration request. Alternatively, the terminal device can carry the second S-NSSAI associated with the requested EHPLMN, and / or the mapping relationship between the second S-NSSAI associated with the requested EHPLMN and the third S-NSSAI associated with the HPLMN. This is beneficial for the AMF network element to determine the S-NSSAI associated with the VPLMN that has a mapping relationship with the requested S-NSSAI based on the S-NSSAI and SLA requested by the terminal device, and to provide network services to the terminal device according to the determined S-NSSAI associated with the VPLMN, so as to meet the service needs of the terminal device.

[0257] It can be seen that the second S-NSSAI requested by the AMF network element and the second S-NSSAI sent to the terminal device can be at least one of the following: the S-NSSAI that the terminal device is allowed to access, or the S-NSSAI configured by the terminal device.

[0258] In one possible approach, when the first slice response received by the AMF network element includes a second S-NSSAI, the AMF network element can determine the mapping relationship between the second S-NSSAI and the first S-NSSAI based on the second S-NSSAI included in the first slice response. Therefore, the AMF network element can send at least one of the following to the terminal device: the second S-NSSAI, and the mapping relationship between the second S-NSSAI and the first S-NSSAI.

[0259] For example, the first slice response includes S-NSSAI#a, S-NSSAI#b, and S-NSSAI#c, and the first S-NSSAI includes S-NSSAI#1, S-NSSAI#2, and S-NSSAI#3. The AMF network element determines the mapping between S-NSSAI#a and S-NSSAI#1, S-NSSAI#b and S-NSSAI#2, and S-NSSAI#c and S-NSSAI#3. Thus, the AMF network element can send S-NSSAI#a, S-NSSAI#b, and S-NSSAI#c, as well as the mapping between S-NSSAI#a and S-NSSAI#1, S-NSSAI#b and S-NSSAI#2, and S-NSSAI#c and S-NSSAI#3 to the terminal device.

[0260] In another possible approach, when the first slice response received by the AMF network element includes the second S-NSSAI and the mapping relationship between the second S-NSSAI and the first S-NSSAI, the AMF network element can directly send at least one of the following to the terminal device: the second S-NSSAI and the mapping relationship between the second S-NSSAI and the first S-NSSAI.

[0261] As can be seen, in this embodiment of the application, when a terminal device belonging to the second PLMN selects to access the PLMN as the equivalent PLMN (third PLMN) of the second PLMN, the AMF network element located in the first PLMN obtains the network slice associated with the third PLMN through interaction with the first NSSF network element located in the first PLMN and the second NSSF network element located in the second PLMN or the second PLMN. This facilitates the AMF network element to send the network slice associated with the EHPLMN to the terminal device, and further facilitates the terminal device to carry the requested network slice associated with the EHPLMN when it subsequently selects to access the PLMN based on the EHPLMN again, so that the AMF network element can provide network services to the terminal device based on the requested network slice associated with the EHPLMN.

[0262] This application embodiment also takes a terminal device belonging to the second PLMN in operating system #2 (OP#2) as an example, which accesses the access network device shared by operating system #1 (OP#1) based on the third PLMN, and OP#1 is the operating system of the first PLMN, and the second NSSF network element is located in the second PLMN (OP#2). Figure 5 The communication method shown will be explained. Figure 6 This is a schematic diagram of the interaction of the communication method. The interaction process includes, but is not limited to, the following steps:

[0263] S601. The identifier of the third PLMN of the access network equipment broadcast terminal equipment of the first PLMN.

[0264] In this context, the access network device located in the first PLMN is an access network device shared by OP#1 with other operating systems; for example, OP#1 can share this access network device with OP#2. Additionally, the terminal device in S601 belongs to the second PLMN, which is the PLMN of OP#2. Therefore, the terminal device can access the network through the access network device shared by OP#1.

[0265] Therefore, to ensure that terminal devices in OP#2 within its coverage area can access the network, the access network device located in the first PLMN broadcasts the identifier of the equivalent home PLMN of the terminal device, i.e., broadcasts the identifier of the third PLMN. For example, if the identifier of the second PLMN of the terminal device is 46000, and the identifiers of the equivalent home PLMN of the terminal device include 46002 and 46003, the access network device broadcasts the identifier of the third PLMN as 46003, so that the terminal device can access the network based on the identifier 46003.

[0266] In one possible approach, the access network device pre-configures the identifier of the equivalent PLMN of at least one of the participating operators. For example, the access network device pre-configures the identifier of the third PLMN of OP#2, so that the access network device can broadcast the identifier of the third PLMN so that terminal devices belonging to OP#2 can access the network based on the identifier of the third PLMN.

[0267] In one possible approach, the AMF network element located in the first PLMN can, based on pre-configuration, learn that the access network device located in the first PLMN is broadcasting the EHPLMN identifier of the terminal device.

[0268] S602. The terminal device sends a registration request message to the access network device, the registration request message including the identifier of the third PLMN. Correspondingly, the access network device receives the registration request message from the terminal device.

[0269] If a terminal device is located within the coverage area of ​​an access network device in S601, and the identifier of its HPLMN (the identifier of the second PLMN) cannot be found, the terminal device will select the identifier of its EHPLMN (the identifier of the third PLMN) broadcast by the access network device to access the network. Therefore, during the registration process, the terminal device sends a registration request to the access network device that includes the identifier of the third PLMN.

[0270] In an optional implementation, the registration request message further includes an indication #a, which instructs the network device to generate the requested NSSAI from the terminal device based on the default configured NSSAI. In this approach, the terminal device can be assumed to be configured with the default configured NSSAI but not with the configured NSSAI. The terminal device uses indication #a to instruct the network device to generate the requested NSSAI from the default configured NSSAI.

[0271] In another optional implementation, the registration request message does not include the Requested NSSAI. In this approach, it can be assumed that the terminal device has not been configured with a Configured NSSAI, and therefore cannot construct a Requested NSSAI, thus the registration request message sent to the access network device does not include the Requested NSSAI.

[0272] S603. The access network equipment determines the AMF network element based on the third PLMN selected by the terminal equipment. The AMF network element is located in the first PLMN.

[0273] Specifically, the access network device determines the AMF network element located in the first PLMN based on the identifier of the third PLMN carried in the registration request message. Based on the identifier of the third PLMN selected by the terminal device, the access network device determines that the terminal device accesses the first PLMN through indirect network sharing. Therefore, the AMF network element providing network services to this terminal device is the AMF network element located in the first PLMN, which is also the AMF network element in OP#1, and thus the AMF network element providing network services to the access network device.

[0274] S604. The access network device sends a service request to the designated AMF network element, the service request including the identifier of the third PLMN. Correspondingly, the AMF network element receives the service request from the access network device.

[0275] In one possible approach, the service request is carried in an N2 message. Optionally, the N2 message may also include a non-access layer message (NAS message).

[0276] Based on the third PLMN and the SUPI of the terminal device, the S605.AMF network element determines that the terminal device is accessed through indirect network sharing.

[0277] The AMF network element can determine whether a terminal device belongs to the second PLMN based on the SUPI of the terminal device. Specifically, the AMF network element can determine whether the terminal device belongs to the second PLMN based on the fields included in the SUPI. The AMF network element can also determine that the third PLMN selected by the terminal device is the EHPLMN based on the stored HPLMN ID and EHPLMN ID of each participating operator, as well as the identifier of the third PLMN selected by the terminal device. Since the third PLMN selected by the terminal device is not the terminal device's home PLMN (second PLMN), but rather the terminal device's EHPLMN, the AMF network element determines that the terminal device accesses the network through indirect network sharing.

[0278] The S606.AMF network element determines to issue at least one of the following to the terminal device: a configured NSSAI and an allowed NSSAI, wherein the configured NSSAI and the allowed NSSAI are NSSAIs associated with the third PLMN.

[0279] In one possible approach, the AMF network element can determine to send the configured NSSAI to the terminal device under at least one of the following circumstances: Circumstance 1: The terminal device's registration request carries indication#a, which instructs the network device to generate the terminal device's Requested NSSAI based on the Default Configured NSSAI; Circumstance 2: The terminal device's registration request does not carry Requested NSSAI; Circumstance 3: The network slice subscribed to by the terminal device has been updated.

[0280] Based on the above description in S502, if either condition 1 or condition 2 is met, it indicates that the terminal device has not been configured with Configured NSSAI. Therefore, the AMF network element determines that the terminal device is sending Configured NSSAI when either condition 1 or condition 2 is met. If condition 3 is met, i.e., when the network slice subscribed to by the terminal device is updated, the AMF network element also determines that the terminal device is sending Configured S-NSSAI.

[0281] In one possible approach, the AMF network element determines that the terminal device sends an Allowed NSSAI when the terminal device successfully registers.

[0282] In one possible approach, the AMF network element determines that the terminal device sends Configured S-NSSAI and Allowed NSSAI when at least one of the following conditions is met: condition 1, condition 2, condition 3, and the terminal device successfully registers.

[0283] Specifically, the Configured S-NSSAI sent by the AMF network element to the terminal device is the Configured S-NSSAI used by the terminal device in the EHPLMN, and the Allowed S-NSSAI sent to the terminal device is the Allowed S-NSSAI used by the terminal device in the EHPLMN. In other words, each S-NSSAI contained in the Configured S-NSSAI is associated with the EHPLMN, and each S-NSSAI contained in the Allowed S-NSSAI is associated with the EHPLMN. This is because, for the terminal device, the PLMN it accesses is the third PLMN (EHPLMN), so the AMF network element will issue the Configured S-NSSAI used in the EHPLMN to the terminal device, enabling the terminal device to trigger subsequent registration processes based on the Configured S-NSSAI. Similarly, the AMF network element will issue Allowed S-NSSAI used in EHPLMN to the terminal device, so that the terminal device can trigger the subsequent session establishment process based on Allowed S-NSSAI.

[0284] The S607.AMF network element requests the UDM network element to obtain the NSSAI signed by the terminal equipment. The signed NSSAI includes the first S-NSSAI, which is the S-NSSAI associated with the second PLMN.

[0285] Among them, the UDM network element is located in the second PLMN, that is, the UDM network element is the UDM network element in the terminal equipment HPLMN, or in other words, the UDM network element is the UDM network element in OP#2.

[0286] If the UDM network element located in the second PLMN stores the terminal device's Subscribed NSSAI, then the AMF network element requests the Subscribed NSSAI from the UDM network element to obtain the first S-NSSAI. Therefore, the first S-NSSAI is the S-NSSAI subscribed to by the terminal device.

[0287] The implementation method of the AMF network element requesting the UDM network element to obtain the Subscribed NSSAI of the terminal device can be found in the implementation method in S502 above, and will not be repeated here.

[0288] The S608.AMF network element sends a first slice request to the first NSSF network element. The first slice request includes the identifier of the second PLMN, the identifier of the third PLMN, and the first S-NSSAI. Correspondingly, the first NSSF network element receives the first slice request from the AMF network element.

[0289] The AMF network element sends a first slice request to the first NSSF network element to request the acquisition of a second S-NSSAI mapped to the first S-NSSAI. This facilitates the AMF network element in issuing at least one of the following to the terminal device: Configured S-NSSAI or Allowed S-NSSAI. Therefore, the second S-NSSAI can be Configured S-NSSAI and / or Allowed S-NSSAI.

[0290] In an optional implementation, the first slice request further includes first indication information, which is used to indicate the discovery of a second NSSF network element located in the second PLMN. The indication method is as described in S502 above and will not be repeated here. This method facilitates the first NSSF network element in identifying the second NSSF network element located in the second PLMN, and further facilitates the first NSSF network element in requesting the second NSSF network element to obtain the second S-NSSAI mapped to the first S-NSSAI.

[0291] S609. The first NSSF network element sends a second slice request to the second NSSF network element located in the second PLMN. The second slice request includes the identifier of the second PLMN, the identifier of the third PLMN, and the first S-NSSFAI. Correspondingly, the second NSSF network element located in the second PLMN receives the second slice request from the first NSSF network element.

[0292] The second slice request may be the same message as the first slice request, or it may be a different message. For details on its implementation, please refer to the above-described S503, which will not be repeated here.

[0293] In an optional implementation, the first NSSF network element further determines the second NSSF network element located in the second PLMN based on the first indication information. Specifically, the first NSSF network element requests the second NSSF network element located in the second PLMN from the NRF network element located in the second PLMN based on the first indication information. Specific implementation details can be found in S503 above and will not be repeated here.

[0294] In another optional implementation, when the first slice request does not include the first indication information, the first NSSF network element requests the NRF network element located in the second PLMN to obtain the second NSSF network element located in the second PLMN based on the identifier of the second PLMN in the first slice request. The implementation method can be found above and will not be repeated here.

[0295] S610. The second NSSF network element determines the second S-NSSAI mapped to the first S-NSSAI based on the identifier of the second PLMN and the identifier of the third PLMN.

[0296] The second NSSF network element located in the second PLMN stores the mapping relationship between the NSSAI associated with the EHPLMN and the NSSAI associated with the HPLMN of the terminal device. Then, the second NSSF network element can determine the second S-NSSAI mapped to the first S-NSSAI based on the identifier of the second PLMN and the identifier of the third PLMN in the second slice request, as well as the stored slice mapping relationship.

[0297] For example, the HPLMN identifier of the terminal device is 46000, and the EHPLMN identifiers of the terminal device include 46002 and 46003. The PLMNs corresponding to 46000, 46002, and 46003 are denoted as PLMN#a, PLMN#b, and PLMN#c, respectively. The second NSSF network element located in the second PLMN stores the mapping relationship between the NSSAI associated with PLMN#a and the NSSAI associated with PLMN#b, as well as the mapping relationship between the NSSAI associated with PLMN#a and the NSSAI associated with PLMN#c. If the second slice request includes the second PLMN with identifier 46000 and the included third PLMN with identifier 46003, then the second NSSF network element determines the S-NSSAI associated with the PLMN identified by identifier 46000 and the S-NSSAI associated with the PLMN identified by identifier 46003 from the stored slice mapping relationship.

[0298] S611. The second NSSF network element sends a second slice response to the first NSSF network element, the second slice response including the second S-NSSAI. Correspondingly, the first NSSF network element receives the second slice response from the second NSSF network element.

[0299] S612. The first NSSF network element sends a first slice response to the AMF network element, the first slice response including the second S-NSSAI. Correspondingly, the AMF network element receives the first slice response from the first NSSF network element.

[0300] The first slice response and the second slice response may be the same message or different messages. For specific implementation details, please refer to the above-described S505, which will not be repeated here.

[0301] In one optional implementation, the second slice response and the first slice response further include a mapping relationship between the second S-NSSAI and the first S-NSSAI.

[0302] S613. The AMF network element sends a registration acceptance message for the terminal device to the access network device. The registration acceptance message includes at least one of the following: a second S-NSSAI, and the mapping relationship between the second S-NSSAI and the first S-NSSAI. Correspondingly, the access network device receives the registration acceptance message from the AMF network element.

[0303] S614. The access network device sends a registration acceptance message to the terminal device. Correspondingly, the terminal device receives the registration acceptance message from the access network device.

[0304] The implementation methods of S611 to S614 can be found in S504 and S505 above, and will not be repeated here.

[0305] As can be seen, in this embodiment of the application, when the AMF network element located in the first PLMN determines, based on the PLMN (third PLMN) selected by the terminal device and the SUPI of the terminal device, that the terminal device accesses the network via indirect network sharing, and the AMF network element determines that it will send the network slice associated with the third PLMN to the terminal device, the AMF network element triggers the interaction between the first NSSF network element located in the first PLMN (i.e., the NSSF network element accessed by the terminal device, the NSSF network element deployed in the main operator) and the second NSSF network element located in the second PLMN (i.e., the NSSF network element deployed in the participating operator, the NSSF network element located in the second PLMN), and obtains the network slice associated with the EHPLMN mapped by the network slice associated with the HPLMN from the second NSSF network element located in the second PLMN. Furthermore, the AMF network element can issue at least one of the following to the terminal device: the network slice associated with the EHPLMN, and the mapping relationship between the network slice associated with the EHPLMN and the network slice associated with the HPLMN. This is beneficial for the terminal device to carry the requested network slice associated with the EHPLMN when it selects the EHPLMN to access the network again in the future, so that the AMF network element can provide network services to the terminal device based on the requested network slice associated with the EHPLMN.

[0306] This application embodiment also takes a terminal device belonging to the second PLMN in operating system #2 (OP#2) as an example, which accesses the access network device shared by operating system #1 (OP#1) based on the third PLMN, and OP#1 is the operating system of the first PLMN, and the second NSSF network element is located in the third PLMN (OP#3). Figure 5 The communication method shown will be explained. Figure 7This is a schematic diagram of the interaction of the communication method. The interaction process includes, but is not limited to, the following steps:

[0307] S701. The identifier of the third PLMN of the access network equipment broadcast terminal equipment of the first PLMN.

[0308] S702. The terminal device sends a registration request message to the access network device, the registration request message including the identifier of the third PLMN. Correspondingly, the access network device receives the registration request message from the terminal device.

[0309] S703. The access network equipment determines the AMF network element based on the third PLMN selected by the terminal equipment. The AMF network element is located in the first PLMN.

[0310] S704. The access network device sends a service request to the identified AMF network element, the service request including the identifier of the third PLMN. Correspondingly, the AMF network element receives the service request from the access network device.

[0311] Based on the third PLMN and the SUPI of the terminal device, the S705.AMF network element determines that the terminal device is accessed through indirect network sharing.

[0312] The S706.AMF network element determines to issue at least one of the following to the terminal device: a configured NSSAI and an allowed NSSAI, wherein the configured NSSAI and the allowed NSSAI are NSSAIs associated with the third PLMN.

[0313] The S707.AMF network element requests the UDM network element to obtain the NSSAI signed by the terminal equipment. The signed NSSAI includes the first S-NSSAI, which is the S-NSSAI associated with the second PLMN.

[0314] The S708.AMF network element sends a first slice request to the first NSSF network element. The first slice request includes the identifier of the second PLMN, the identifier of the third PLMN, and the first S-NSSAI.

[0315] The implementation methods of S701 to S708 are the same as those described in S601 to S608 above, and will not be repeated here.

[0316] In addition, the first slice request also includes first indication information for indicating the discovery of a second NSSF network element located in the third PLMN. The indication method is as described in S502 above and will not be repeated here. This method helps the first NSSF network element to determine the second NSSF network element located in the third PLMN, and thus helps the first NSSF network element to request the second NSSF network element to obtain the second S-NSSAI mapped to the first S-NSSAI.

[0317] S709. The first NSSF network element sends a second slice request to the second NSSF network element located in the third PLMN. The second slice request includes the identifier of the second PLMN, the identifier of the third PLMN, and the first S-NSSFAI. Correspondingly, the second NSSF network element located in the third PLMN receives the second slice request from the first NSSF network element.

[0318] The second slice request may be the same message as the first slice request, or it may be a different message. For details on its implementation, please refer to the above-described S503, which will not be repeated here.

[0319] In an optional implementation, the first NSSF network element further determines the second NSSF network element located in the third PLMN based on the first indication information. Specifically, the first NSSF network element requests the second NSSF network element located in the third PLMN from the NRF network element located in the second PLMN based on the first indication information. Specific implementation details can be found in S503 above and will not be repeated here.

[0320] In another optional implementation, when the first slice request does not include the first indication information, the first NSSF network element requests the second NSSF network element located in the second PLMN from the NRF network element located in the third PLMN based on the identifier of the third PLMN in the first slice request. The implementation method can be found above and will not be repeated here.

[0321] In addition, the second NSSF network element located in the third PLMN and the first NSSF network element located in the first PLMN belong to different operators. The second NSSF network element located in the third PLMN belongs to operator #3, and the first NSSF network element located in the first PLMN belongs to operator #2.

[0322] S710. The second NSSF network element determines the second S-NSSAI mapped to the first S-NSSAI based on the identifier of the second PLMN and the identifier of the third PLMN.

[0323] The implementation method for determining the second S-NSSAI mapped to the first S-NSSAI based on the identifiers of the second and third PLMNs of the second NSSF network element located in the third PLMN can be referred to in S610 above, where the implementation method for determining the second S-NSSAI mapped to the first S-NSSAI based on the identifiers of the second and third PLMNs of the second NSSF network element located in the second PLMN is described in detail, and will not be repeated here.

[0324] For example, the HPLMN identifier of the terminal device is 46000, and the EHPLMN identifiers of the terminal device include 46002 and 45001. The PLMNs corresponding to 46000, 46002, and 45001 are denoted as PLMN#a, PLMN#b, and PLMN#c, respectively. The second NSSF network element located in the third PLMN stores the mapping relationship between the NSSAI associated with PLMN#a and the NSSAI associated with PLMN#b, as well as the mapping relationship between the NSSAI associated with PLMN#a and the NSSAI associated with PLMN#c. If the second slice request includes the second PLMN identifier 46000 and the included third PLMN identifier 45001, then the second NSSF network element determines the S-NSSAI associated with the PLMN identified by identifier 46000 and the S-NSSAI associated with the PLMN identified by identifier 45001 from the stored slice mapping relationship.

[0325] S711. The second NSSF network element sends a second slice response to the first NSSF network element, the second slice response including the second S-NSSAI. Correspondingly, the first NSSF network element receives the second slice response from the second NSSF network element.

[0326] S712. The first NSSF network element sends a first slice response to the AMF network element, the first slice response including the second S-NSSAI. Correspondingly, the AMF network element receives the first slice response from the first NSSF network element.

[0327] The first slice response and the second slice response may be the same message or different messages. For specific implementation details, please refer to the above-described S505, which will not be repeated here.

[0328] In one optional implementation, the second slice response and the first slice response further include a mapping relationship between the second S-NSSAI and the first S-NSSAI.

[0329] S713. The AMF network element sends a registration acceptance message for the terminal device to the access network device. The registration acceptance message includes at least one of the following: a second S-NSSAI, and the mapping relationship between the second S-NSSAI and the first S-NSSAI. Correspondingly, the access network device receives the registration acceptance message from the AMF network element.

[0330] S714. The access network device sends a registration acceptance message to the terminal device. Correspondingly, the terminal device receives the registration acceptance message from the access network device.

[0331] The implementation methods of S713 and S714 are the same as those described in S505 above, and will not be repeated here.

[0332] As can be seen, in this embodiment, when the AMF network element located in the first PLMN determines, based on the PLMN (third PLMN) selected by the terminal device and the SUPI of the terminal device, that the terminal device accesses the network via indirect network sharing, and the AMF network element determines to send the network slice associated with the third PLMN to the terminal device, the AMF network element triggers the interaction between the first NSSF network element located in the first PLMN (i.e., the NSSF network element accessed by the terminal device, the NSSF network element deployed in the main operator) and the second NSSF network element located in the third PLMN (i.e., the NSSF network element deployed in the participating operator, the NSSF network element located in the third PLMN), and obtains the network slice associated with the EHPLMN mapped by the S-NSSAI associated with the HPLMN from the second NSSF network element located in the third PLMN. Furthermore, the AMF network element can issue at least one of the following to the terminal device: the network slice associated with the EHPLMN, and the mapping relationship between the network slice associated with the EHPLMN and the network slice associated with the HPLMN. This is beneficial for the terminal device to carry the requested network slice associated with the EHPLMN when it selects the EHPLMN to access the network again in the future, so that the AMF network element can provide network services to the terminal device based on the requested network slice associated with the EHPLMN.

[0333] The following section further describes the corresponding device implementation scheme in relation to the technical solution described above.

[0334] To achieve the functions of the methods provided in the embodiments of this application, the access and mobility management function network element and the network slicing selection function network element may include hardware structures and / or software modules, and may implement the above functions in the form of hardware structures, software modules, or hardware structures plus software modules. Whether a certain function is implemented in the form of hardware structures, software modules, or hardware structures plus software modules depends on the specific application and design constraints of the technical solution.

[0335] like Figure 8 As shown, this application provides a communication device 800. The communication device 800 can be a component of an access and mobility management function network element (e.g., an integrated circuit, a chip, etc.), or a component of a network slicing selection function network element (e.g., an integrated circuit, a chip, etc.). The communication device 800 can also be other communication units used to implement the methods in the method embodiments of this application. The communication device 800 may include a communication unit 801 and a processing unit 802. In one possible implementation, it may further include a storage unit 803.

[0336] In one possible design, such as Figure 8One or more units may be implemented by one or more processors, or by one or more processors and memory; or by one or more processors and transceivers; or by one or more processors, memory, and transceivers. This application does not limit the implementation in this way. The processors, memory, and transceivers can be configured individually or integrated.

[0337] The communication device 800 is equipped with the functions of the access and mobility management function network elements described in the embodiments of this application, or the functions of the network slicing selection function network elements. For example, the communication device 800 includes a reader / writer that executes the modules, units, or means corresponding to the steps involved in the access and mobility management function network elements in the above method embodiments. The functions, units, or means can be implemented by software, by hardware, by hardware executing corresponding software, or by a combination of software and hardware. For further details, please refer to the corresponding descriptions in the foregoing method embodiments.

[0338] In one possible design, the communication device 800 may include a processing unit 802 and a communication unit 801, the device being applied to an access and mobility management function network element located in a first public terrestrial network (PLMN).

[0339] The processing unit 802 is used to determine that the PLMN selected by the terminal device belonging to the second PLMN is the third PLMN, and the third PLMN is the equivalent PLMN of the second PLMN.

[0340] The communication unit 801 is used to send a first slice request to a first network slice selection function network element located in the first PLMN. The first slice request includes the identifier of the second PLMN, the identifier of the third PLMN, and first network slice selection auxiliary information. The first network slice selection auxiliary information is network slice selection auxiliary information associated with the second PLMN.

[0341] The communication unit 801 is further configured to receive a first slice response from the first network slice selection function network element, the first slice response including second network slice selection auxiliary information mapped to the first network slice selection auxiliary information, the second network slice selection auxiliary information being network slice selection auxiliary information associated with the third PLMN.

[0342] In one optional implementation, the first network slice selection assistance information is the network slice selection assistance information subscribed to by the terminal device.

[0343] In one optional implementation, the second network slice selection assistance information is at least one of the following: network slice selection assistance information that allows the terminal device to access, and network slice selection assistance information configured by the terminal device.

[0344] In one optional implementation, the first slice request further includes first indication information, which is used to indicate the discovery of a second network slice selection function network element; the second network slice selection function network element is located in the second PLMN, or the second network slice selection function network element is located in the third PLMN.

[0345] In one optional implementation, the first slice response further includes a mapping relationship between the first network slice selection assistance information and the second network slice selection assistance information.

[0346] In an optional implementation, the communication unit 801 is further configured to send at least one of the following to the terminal device: the second network slice selection assistance information, and the mapping relationship between the second network slice selection assistance information and the first network slice selection assistance information.

[0347] In one optional implementation, the second PLMN is the home public land network (HPLMN) of the terminal device, and the third PLMN is the equivalent home public land network (EHPLMN) of the terminal device.

[0348] In another possible design, the communication device 800 may include a processing unit 802 and a communication unit 801, the device being applied to a first network slice selection function network element located in a first public terrestrial network (PLMN), the processing unit 802 being used to process signals / signaling;

[0349] The communication unit 801 is configured to receive a first slice request from an access and mobility management function network element located in the first PLMN. The first slice request includes the identifier of the second PLMN, the identifier of the third PLMN, and first network slice selection assistance information. The second PLMN is the home PLMN of the terminal device, the third PLMN is the equivalent PLMN of the second PLMN, and the first network slice selection assistance information is the network slice selection assistance information associated with the second PLMN.

[0350] The communication unit 801 is further configured to send a second slice request to a second network slice selection function network element, the second network slice selection function network element being located in the second PLMN or the third PLMN, the second slice request including the identifier of the second PLMN, the identifier of the third PLMN and the first network slice selection auxiliary information;

[0351] The communication unit 801 is further configured to receive a second slice response from the second network slice selection function network element, the second slice response including second network slice selection auxiliary information mapped to the first network slice selection auxiliary information, the second network slice selection auxiliary information being network slice selection auxiliary information associated with the third PLMN;

[0352] The communication unit 801 is further configured to send a first slice response to the access and mobility management function network element, the first slice response including the second network slice selection assistance information.

[0353] In one optional implementation, the first network slice selection assistance information is the network slice selection assistance information subscribed to by the terminal device.

[0354] In one optional implementation, the second network slice selection assistance information is at least one of the following: network slice selection assistance information that allows the terminal device to access, and network slice selection assistance information configured by the terminal device.

[0355] In one optional implementation, the first slice request further includes first indication information, which is used to indicate the discovery of the second network slice selection function network element; the processing unit 802 is used to determine the second network slice selection function network element based on the first indication information.

[0356] In one optional implementation, when the first indication information is used to indicate the discovery of the second network slice selection function network element located in the second PLMN, the processing unit 802 determines the second network slice selection function network element based on the first indication information, specifically by: sending a discovery request to the network storage function network element, the discovery request including the identifier of the second PLMN; and receiving a discovery response from the network storage function network element, the discovery response including the identifier of the second network slice selection function network element located in the second PLMN.

[0357] In another optional implementation, when the first indication information is used to indicate the discovery of the second network slice selection function network element located in the third PLMN, the processing unit 802 determines the second network slice selection function network element based on the first indication information, specifically by: sending a discovery request to the network storage function network element, the discovery request including the identifier of the third PLMN; and receiving a discovery response from the network storage function network element, the discovery response including the identifier of the second network slice selection function network element located in the third PLMN.

[0358] In one optional implementation, the second slice response and the first slice response further include a mapping relationship between the first network slice selection assistance information and the second network slice selection assistance information.

[0359] In one optional implementation, the second PLMN is the home public land network (HPLMN) of the terminal device, and the third PLMN is the equivalent home public land network (EHPLMN) of the terminal device.

[0360] In another possible design, the communication device 800 may include a processing unit 802 and a communication unit 801, the device being applied to a second network slice selection function network element located in a second PLMN or a third PLMN, the processing unit 802 being used to process signals / signaling;

[0361] The communication unit 801 is configured to receive a second slice request from a first network slice selection function network element located in the first PLMN. The second slice request includes the identifier of the second PLMN, the identifier of the third PLMN, and first network slice selection auxiliary information. The second PLMN is the home PLMN of the terminal device, the third PLMN is the equivalent PLMN of the second PLMN, and the first network slice selection auxiliary information is the network slice selection auxiliary information associated with the second PLMN.

[0362] The communication unit 801 is further configured to send a second slice response to the first network slice selection function network element. The second slice response includes second network slice selection auxiliary information mapped to the first network slice selection auxiliary information. The second network slice selection auxiliary information is network slice selection auxiliary information associated with the third PLMN.

[0363] In one optional implementation, the first network slice selection assistance information is the network slice selection assistance information subscribed to by the terminal device.

[0364] In one optional implementation, the second network slice selection assistance information is at least one of the following: network slice selection assistance information that allows the terminal device to access, and network slice selection assistance information configured by the terminal device.

[0365] In one optional implementation, the second slice response further includes a mapping relationship between the first network slice selection assistance information and the second network slice selection assistance information.

[0366] In one optional implementation, the second PLMN is the home public land network (HPLMN) of the terminal device, and the third PLMN is the equivalent home public land network (EHPLMN) of the terminal device.

[0367] In one optional implementation, the processing unit 802 is used to determine the second network slice selection assistance information mapped to the first network slice selection assistance information based on the identifier of the second PLMN and the identifier of the third HPLMN.

[0368] The embodiments of this application and the method embodiments shown above are based on the same concept and have the same technical effects. For the specific principles, please refer to the description of the embodiments shown above, which will not be repeated here.

[0369] This application embodiment also provides a communication device 900. Figure 9 This is a schematic diagram of the communication device 900. The communication device 900 can be an access and mobility management function (AMU) network element, or a chip, chip system, or processor that implements the above methods within the AMU network element; alternatively, it can be a network slicing selection function (BSC) network element, or a chip, chip system, or processor that supports the network slicing selection function network element in implementing the above methods. This device can be used to implement the methods described in the above method embodiments, and specific details can be found in the descriptions of the above method embodiments.

[0370] The communication device 900 may include one or more processors 901. The processor 901 may be a general-purpose processor or a special-purpose processor. For example, it may be a baseband processor, digital signal processor, application-specific integrated circuit (ASIC), field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic device, discrete hardware component, or central processing unit (CPU). The baseband processor can be used to process communication protocols and communication data, while the CPU can be used to control the communication device (e.g., base station, baseband chip, terminal, terminal chip, distributed unit (DU) or centralized unit (CU), etc.), execute software programs, and process data from the software programs.

[0371] In one possible implementation, the communication device 900 may include one or more memories 902, which may store instructions 904. These instructions can be executed on the processor 901, causing the communication device 900 to perform the method described in the above method embodiments. The instructions can be replaced with programs. In another possible implementation, the memory 902 may also store data. The processor 901 and the memory 902 may be configured separately or integrated together. The processor 901 is used to parse signaling information and process related data; the memory 902 contains stored signaling information and pre-agreed preset values, etc.

[0372] In one possible implementation, the communication device 900 may further include a transceiver 905 and an antenna 906. The transceiver 905, which may be referred to as a transceiver unit, transceiver, or transceiver circuit, is used to implement transceiver functions. The transceiver 905 may include a receiver and a transmitter. The receiver, which may be referred to as a receiver or receiving circuit, is used to implement a receiving function; the transmitter, which may be referred to as a transmitter or transmitting circuit, is used to implement a transmitting function.

[0373] In one possible design, the communication device 900 can be applied to an access and mobility management function network element located in the first PLMN. Specifically, the processor 901 is used to execute S501 in the above communication method; the transceiver 905 is used to execute S502 and S505 in the above communication method.

[0374] In another possible design, the communication device 900 can be applied to the first network slice selection function network element of the first PLMN. Specifically, the transceiver 905 is used to execute S502, S503, S504 and S505 in the above communication method.

[0375] In another possible design, the communication device 900 can be applied to the second network slice selection function network element of the second PLMN or the third PLMN. Specifically, the transceiver 905 is used to execute S503 and S504 in the above communication method.

[0376] In one possible implementation, processor 901 may store instructions 903, which, when executed on processor 901, cause the communication device 900 to perform the methods described in the above method embodiments. Instructions 903 may be embedded in processor 901; in this case, processor 901 may be implemented in hardware.

[0377] The embodiments of this application and any of the above-described communication methods are based on the same concept and have the same technical effects. For the specific principles, please refer to the description of any of the above-described communication methods, which will not be repeated here.

[0378] This application also provides a communication system, which includes a terminal device, an access network device, and a core network device. In another possible design, the system may further include other devices / functional network elements that interact with at least one of the terminal device, the access network device, and the core network device. Specifically, the access and mobility management function network element in the core network device is used to implement the method described by any one of the access and mobility management function network elements in the above method embodiments, and the network slice selection function network element in the core network device is used to implement the method described by any one of the first network slice selection function network element and the second network slice selection function element in the above method embodiments.

[0379] This application also provides a chip including a processor that calls a computer program stored in a memory to enable a communication device including the chip to perform the functions of any of the above method embodiments.

[0380] This application also provides a computer-readable storage medium for storing computer software instructions, which, when executed by a communication device, implement the functions of any of the above method embodiments.

[0381] This application also provides a computer program product for storing computer software instructions, which, when executed by a communication device, implement the functions of any of the above method embodiments.

[0382] This application also provides a computer program that, when run on a computer, implements the functions of any of the above method embodiments.

[0383] The terms "first" and "second," etc., in the specification, claims, and drawings of this application are used to distinguish different objects, not to describe a specific order. "First," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this embodiment, unless otherwise stated, "a plurality of" means two or more.

[0384] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0385] In this application, the term "embodiment" is used to mean that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0386] In the embodiments of this application, "at least one (item)" refers to one or more, "more than one" refers to two or more, and "and / or" is used to describe the association relationship of related objects, indicating that there can be three relationships. For example, "A and / or B" can represent three cases: only A exists, only B exists, and A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the related objects before and after are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0387] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a specific manner to facilitate understanding.

[0388] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions. When the computer instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application 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. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available media may be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., high-density digital video discs (DVDs)), or semiconductor media (e.g., solid-state disks (SSDs)).

Claims

1. A communication method characterized by comprising: The method is applied to an access and mobility management function network element located in a first public land mobile network (PLMN), and the method comprises: determining that a terminal device belonging to a second PLMN selects an accessed PLMN as a third PLMN, the third PLMN being an equivalent PLMN of the second PLMN; sending a first slice request to a first network slice selection function network element located in the first PLMN, the first slice request comprising an identity of the second PLMN, an identity of the third PLMN, and first network slice selection assistance information, the first network slice selection assistance information being network slice selection assistance information associated with the second PLMN; receiving a first slice response from the first network slice selection function network element, the first slice response comprising second network slice selection assistance information mapped with the first network slice selection assistance information, the second network slice selection assistance information being network slice selection assistance information associated with the third PLMN.

2. The method of claim 1, wherein: the first network slice selection assistance information is network slice selection assistance information to which the terminal device is subscribed.

3. The method of claim 1 or 2, wherein: the second network slice selection assistance information is at least one of the following: network slice selection assistance information that allows the terminal device to access, and network slice selection assistance information that is configured for the terminal device.

4. The method of any one of claims 1 to 3, wherein: the first slice request further comprises first indication information, the first indication information being used to indicate that a second network slice selection function network element is found; the second network slice selection function network element is located in the second PLMN, or the second network slice selection function network element is located in the third PLMN.

5. The method of any one of claims 1 to 4, wherein: the first slice response further comprises a mapping relationship between the first network slice selection assistance information and the second network slice selection assistance information.

6. The method according to any one of claims 1 to 5, characterized in that, The method further comprises: sending at least one of the following to the terminal device: the second network slice selection assistance information, and the mapping relationship between the second network slice selection assistance information and the first network slice selection assistance information.

7. The method of any one of claims 1 to 6, wherein: the second PLMN is a home public land mobile network (HPLMN) of the terminal device, and the third PLMN is an equivalent home public land mobile network (EHPLMN) of the terminal device.

8. A communication method, characterized in that, The method is applied to a first network slice selection function network element located in a first public land mobile network (PLMN), and the method comprises: receiving a first slice request from an access and mobility management function network element located in the first PLMN, the first slice request comprising an identity of a second PLMN, an identity of a third PLMN, and first network slice selection assistance information, the second PLMN being a home PLMN of a terminal device, the third PLMN being an equivalent PLMN of the second PLMN, the first network slice selection assistance information being network slice selection assistance information associated with the second PLMN; sending a second slice request to a second network slice selection function network element located in the second PLMN or the third PLMN, the second slice request comprising the identity of the second PLMN, the identity of the third PLMN, and the first network slice selection assistance information; receiving a second slice response from the second network slice selection function network element, the second slice response comprising second network slice selection assistance information mapped from the first network slice selection assistance information, the second network slice selection assistance information being network slice selection assistance information associated with the third PLMN; sending a first slice response to the access and mobility management function network element, the first slice response comprising the second network slice selection assistance information.

9. The method of claim 8, wherein the first network slice selection assistance information is network slice selection assistance information to which the terminal device is subscribed.

10. The method of claim 8 or 9, wherein the second network slice selection assistance information is at least one of: network slice selection assistance information that allows the terminal device to access, and network slice selection assistance information that is configured for the terminal device.

11. The method of any of claims 8 to 10, wherein the first slice request further comprises first indication information, the first indication information being used to indicate discovery of the second network slice selection function network element; and the method further comprises determining the second network slice selection function network element based on the first indication information. when the first indication information is used to indicate discovery of the second network slice selection function network element located in the second PLMN, the determining the second network slice selection function network element based on the first indication information comprises: sending a discovery request to a network repository function network element, the discovery request comprising the identity of the second PLMN; and receiving a discovery response from the network repository function network element, the discovery response comprising an identity of the second network slice selection function network element located in the second PLMN. when the first indication information is used to indicate discovery of the second network slice selection function network element located in the third PLMN, the determining the second network slice selection function network element based on the first indication information comprises:

12. The method of claim 11, wherein, sending a discovery request to a network repository function network element, the discovery request comprising the identity of the third PLMN; and ​ ​ 13. The method of claim 11, wherein, ​ ​ receiving a discovery response from the network storage function network element, the discovery response comprising an identity of the second network slice selection function network element located in the third PLMN.

14. The method of any of claims 8-13, wherein: the second slice response and the first slice response further comprise a mapping relationship between the first network slice selection assistance information and the second network slice selection assistance information.

15. The method of any of claims 8-14, wherein: the second PLMN is a home public land mobile network (HPLMN) of the terminal device, and the third PLMN is an equivalent home public land mobile network (EHPLMN) of the terminal device.

16. A method of communication, comprising: The method is applied to a second network slice selection function network element located in a second PLMN or a third PLMN, and the method comprises: receiving a second slice request from a first network slice selection function network element located in a first PLMN, the second slice request comprising an identity of the second PLMN, an identity of the third PLMN, and first network slice selection assistance information, the second PLMN being a home PLMN of a terminal device, the third PLMN being an equivalent PLMN of the second PLMN, and the first network slice selection assistance information being network slice selection assistance information associated with the second PLMN; sending a second slice response to the first network slice selection function network element, the second slice response comprising second network slice selection assistance information mapped with the first network slice selection assistance information, the second network slice selection assistance information being network slice selection assistance information associated with the third PLMN.

17. The method of claim 16, wherein: the first network slice selection assistance information is network slice selection assistance information to which the terminal device is subscribed.

18. The method of claim 16 or 17, wherein: the second network slice selection assistance information is at least one of network slice selection assistance information that allows the terminal device to access and network slice selection assistance information configured for the terminal device.

19. The method of any of claims 16-18, wherein: the second slice response further comprises a mapping relationship between the first network slice selection assistance information and the second network slice selection assistance information.

20. The method of any of claims 16-19, wherein: the second PLMN is a home public land mobile network (HPLMN) of the terminal device, and the third PLMN is an equivalent home public land mobile network (EHPLMN) of the terminal device.

21. The method according to any one of claims 16 to 20, characterized in that, The method further comprises: determining the second network slice selection assistance information mapped with the first network slice selection assistance information based on the identity of the second PLMN and the identity of the third HPLMN.

22. A communications device, characterized by The communication device comprises modules for performing the method according to any one of claims 1 to 7, or modules for performing the method according to any one of claims 8 to 15, or modules for performing the method according to any one of claims 16 to 21.

23. A communications device, characterized by The communication device comprises a processor configured to perform the method according to any one of claims 1 to 7, or configured to perform the method according to any one of claims 8 to 15, or configured to perform the method according to any one of claims 16 to 21.

24. A computer-readable storage medium, characterized in that, The computer readable storage medium has stored thereon instructions which, when executed on a computer, cause the method according to any one of claims 1 to 7 to be performed, or cause the method according to any one of claims 8 to 15 to be performed, or cause the method according to any one of claims 16 to 21 to be performed.

25. A computer program product comprising instructions, wherein: The computer readable storage medium has stored thereon instructions which, when executed on a computer, cause the method according to any one of claims 1 to 7 to be performed, or cause the method according to any one of claims 8 to 15 to be performed, or cause the method according to any one of claims 16 to 21 to be performed.

Images