Communication method and communication apparatus

Abstract

Provided in the present application is a communication method, comprising: a terminal device urgently registering with a first network; the terminal device reselecting from the first network to a second network; when executing an emergency service, the terminal device sending to a mobility management network element of the second network a request message requesting emergency registration to the second network, and after receiving the request message requesting the emergency registration, the second network entering an emergency registration state; and when not executing an emergency service, the terminal device sending to the mobility management network element of the second network a request message requesting an initial registration to the second network, and after receiving the request message requesting the initial registration, the second network entering a non-emergency registration state, so as to realize the synchronization of the registration states of the second network and the terminal device.

Description

Communication method and communication device

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on February 7, 2024, with application number 202410175890.3 and invention name “A communication method and communication device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of communications, and more specifically, to a communication method and a communication device. Background Art

[0003] Long term evolution (LTE) networks and fifth generation (5 th Generation, 5G) or new radio, NR networks can interoperate. When user equipment (UE) triggers emergency registration on the LTE network, the UE is in the emergency registration state (the UE has established an emergency packet data network (PDN) session). At this time, the UE can only initiate emergency services and cannot initiate ordinary services (ordinary services can also be understood as non-emergency services). During the interoperation process between the LTE network and the 5G network or the LTE network and the NR network, the protocol clearly stipulates: If the PDN on the LTE network cannot be mapped to the 5G network or the NR network, the UE can release this PDN session locally, and if the UE is in the emergency registration state, it needs to wait until T3512 times out before it can exit the emergency registration.

[0004] When the UE reselects from the LTE network to the 5G network or the NR network, the UE is still in the emergency registration state, but there is no emergency data packet unit (PDU) to carry it. Without the emergency PDU to carry it, the UE cannot receive the paging of the emergency call from the network side. At this time, ordinary services cannot be initiated, and paging of emergency services cannot be received. The UE is always in the emergency registration state, which affects the user experience. In addition, if the LTE network and the NR network or the LTE network and the 5G network cannot communicate with each other, for example, the NR network or the 5G network may be in a non-emergency registration state, but the UE is in an emergency registration state, resulting in the problem of the registration status of the network side and the UE being out of sync. Summary of the Invention

[0005] The present application provides a communication method that can support solving the problem of registration status asynchrony between the network side and the terminal device.

[0006] In a first aspect, a communication method is provided, which is executed by a terminal device. The terminal device here can refer to the terminal device itself or a processor, module, chip, or chip system that implements the method in the terminal device. The method includes: emergency registration to a first network; reselecting from the first network to a second network; sending a first request message or a second request message to a first mobility management network element, wherein the first mobility management network element belongs to the second network, the first request message is used to request emergency registration to the second network, and the second request message is used to request initial registration to the second network.

[0007] Specifically, when the first network is an LTE network, the terminal device's emergency registration with the first network can be understood as the terminal device's emergency attachment to the first network, that is, "emergency registration" can be understood as "emergency attachment." For example, the terminal device sends an Attach Request message to a mobility management network element (e.g., a mobility management entity (MME) network element) of the LTE network, and then the terminal device urgently attaches to the first network (LTE network).

[0008] It should be understood that the specific description of the emergency attachment process can be referred to the existing technology and will not be repeated here.

[0009] Accordingly, the first request message may be an emergency attachment request message, and the second request message may be an attachment request message. It should be understood that the embodiment of the present application does not impose any restrictions on the message names.

[0010] Specifically, when the first network is an NR network or a 5G network, the terminal device urgently registers with the first network, which can be understood as the terminal device urgently registering with the first network. For example, the terminal device sends an emergency registration request (Registration Request) message to the mobility management network element of the NR network or the 5G network (such as the access and mobility management function AMF network element), and then the terminal device urgently registers with the first network (5G network or NR network).

[0011] Accordingly, the first request message may be an emergency registration request message, and the second request message may be an initial registration request message. It should be understood that the embodiment of the present application does not impose any restrictions on the message name.

[0012] It should be understood that the specific description of the emergency registration process can be referred to the existing technology and will not be repeated here.

[0013] According to the above technical solution, when a terminal device is performing an emergency service, it sends a request message to the mobility management network element of the second network requesting emergency registration with the second network. After receiving the request message, the second network enters the emergency registration state. When a terminal device is not performing an emergency service, it sends a request message to the mobility management network element of the second network (i.e., the first mobility management network element) requesting initial registration with the second network. After receiving the request message, the second network enters the non-emergency registration state, thereby achieving registration status synchronization between the second network and the terminal device.

[0014] In conjunction with the first aspect, in certain implementations of the first aspect, sending the first request message or the second request message to the first mobility management network element includes: sending the first request message or the second request message to the first mobility management network element when the first network and the second network do not communicate with each other. According to the above technical solution, it is possible to support resolving the issue of registration status asynchrony between the network side and the terminal device.

[0015] In conjunction with the first aspect, in certain implementations of the first aspect, the first network and the second network do not communicate with each other, including: the second network is not an equivalent network of the first network; or the first mobility management network element and the mobility management network element of the first network do not have an interface for mutual communication. According to the above technical solution, the problem of asynchronous registration status between the network side and the terminal device can be resolved.

[0016] In conjunction with the first aspect, in certain implementations of the first aspect, sending the first request message or the second request message to the first mobility management network element includes: sending the first request message to the first mobility management network element when the terminal device is performing an emergency service. According to the above technical solution, it is possible to support resolving the problem of registration status being out of sync between the network side and the terminal device.

[0017] In conjunction with the first aspect, in certain implementations of the first aspect, sending the first request message or the second request message to the first mobility management network element includes: sending the second request message to the first mobility management network element when the terminal device is not performing emergency services. According to the above technical solution, it is possible to support resolving the problem of registration status asynchrony between the network side and the terminal device.

[0018] In conjunction with the first aspect, in certain implementations of the first aspect, before sending the first request message or the second request message to the first mobility management network element, the method further includes: entering a deregistered state. According to the above technical solution, it is possible to resolve the issue of registration status asynchrony between the network side and the terminal device.

[0019] In conjunction with the first aspect, in certain implementations of the first aspect, the first network and the second network are different PLMNs. According to the above technical solution, the problem of asynchronous registration status between the network side and the terminal device can be solved.

[0020] In conjunction with the first aspect, in certain implementations of the first aspect, the first network and the second network are the same PLMN with different access standards, where the access standards include any one of the following: an LTE system, a 5G system, or a NR system. According to the above technical solution, it is possible to resolve the issue of registration status asynchrony between the network side and the terminal device.

[0021] In a second aspect, a communication method is provided, which is executed by a terminal device. The terminal device here can refer to the terminal device itself, or to a processor, module, chip, or chip system that implements the method in the terminal device. The method includes: emergency registration to a first network; reselecting from the first network to a second network; obtaining first indication information, which is used to instruct the terminal device to enter a non-emergency registration state; and determining, based on the first indication information, to send a third request message to a first mobility management network element, which belongs to the second network, and the third request message is used to request initial registration to the second network.

[0022] Specifically, when the first network is an LTE network, the terminal device's emergency registration with the first network can be understood as the terminal device's emergency attachment to the first network, that is, "emergency registration" can be understood as "emergency attachment." For example, the terminal device sends an Attach Request message to a mobility management network element (e.g., a mobility management entity (MME) network element) of the LTE network, and then the terminal device urgently attaches to the first network (LTE network).

[0023] It should be understood that the specific description of the emergency attachment process can be referred to the existing technology and will not be repeated here.

[0024] Accordingly, the first request message may be an emergency attachment request message, and the second request message may be an attachment request message. It should be understood that the embodiment of the present application does not impose any restrictions on the message names.

[0025] Specifically, when the first network is an NR network or a 5G network, the terminal device urgently registers with the first network, which can be understood as the terminal device urgently registering with the first network. For example, the terminal device sends an emergency registration request (Registration Request) message to the mobility management network element of the NR network or the 5G network (such as the access and mobility management function AMF network element), and then the terminal device urgently registers with the first network (5G network or NR network).

[0026] Accordingly, the first request message may be an emergency registration request message, and the second request message may be an initial registration request message. It should be understood that the embodiment of the present application does not impose any restrictions on the message name.

[0027] It should be understood that the specific description of the emergency registration process can be referred to the existing technology and will not be repeated here.

[0028] According to the above technical solution, the terminal device obtains the first indication information, which is used to instruct the terminal device to enter the non-emergency registration state. The terminal device initiates the initial registration process to the second network according to the first indication information, thereby achieving state synchronization between the terminal device and the second network.

[0029] In conjunction with the second aspect, in certain implementations of the second aspect, before obtaining the first indication information, the method further includes: sending a fourth request message to the first mobility management network element, the fourth request message being used to request mobile registration with the second network; and obtaining the first indication information includes: receiving a first response message from the first mobility management network element, the first response message including the first indication information. According to the above technical solution, it is possible to resolve the issue of registration status asynchrony between the network side and the terminal device.

[0030] Specifically, when the access standard of the second network is NR or 5G system, the fourth request message may be a mobility registration request message, and the first response message may be a mobility registration accept message.

[0031] Specifically, when the access standard of the second network is an LTE system, the fourth request message may be a tracking area update request message, the first response message may be a tracking area update accept message, and the session management context may be a PDN session.

[0032] In conjunction with the second aspect, in certain implementations of the second aspect, the first network and the second network are different PLMNs. According to the above technical solution, it is possible to solve the problem of asynchronous registration status between the network side and the terminal device.

[0033] In conjunction with the second aspect, in certain implementations of the second aspect, the first network and the second network are the same PLMN with different access standards, where the access standards include any one of the following: an LTE system, a 5G system, or a NR system. According to the above technical solution, it is possible to support resolving the issue of registration status asynchrony between the network side and the terminal device.

[0034] On the third aspect, a communication method is provided, which is executed by a terminal device. The terminal device here can refer to the terminal device itself, or to a processor, module, chip, or chip system that implements the method in the terminal device. The method includes: emergency registration to a first network; reselecting from the first network to a second network; sending a fifth request message to a first mobility management network element, the first mobility management network element belongs to the second network, the fifth request message is used to request to move to the second network, and the fifth request message includes second indication information, and the second indication information is used to indicate that the registration status of the terminal device is an emergency registration status.

[0035] Specifically, when the first network is an LTE network, the terminal device's emergency registration with the first network can be understood as the terminal device's emergency attachment to the first network, that is, "emergency registration" can be understood as "emergency attachment." For example, the terminal device sends an Attach Request message to a mobility management network element (e.g., a mobility management entity (MME) network element) of the LTE network, and then the terminal device urgently attaches to the first network (LTE network).

[0036] It should be understood that the specific description of the emergency attachment process can be referred to the existing technology and will not be repeated here.

[0037] Accordingly, the first request message may be an emergency attachment request message, and the second request message may be an attachment request message. It should be understood that the embodiment of the present application does not impose any restrictions on the message names.

[0038] Specifically, when the first network is an NR network or a 5G network, the terminal device urgently registers with the first network, which can be understood as the terminal device urgently registering with the first network. For example, the terminal device sends an emergency registration request (Registration Request) message to the mobility management network element of the NR network or the 5G network (such as the access and mobility management function AMF network element), and then the terminal device urgently registers with the first network (5G network or NR network).

[0039] It should be understood that the specific description of the emergency registration process can be referred to the existing technology and will not be repeated here.

[0040] Accordingly, the first request message may be an emergency registration request message, and the second request message may be an initial registration request message. It should be understood that the embodiment of the present application does not impose any restrictions on the message name.

[0041] According to the above technical solution, the terminal device sends a second indication message to the mobility management network element of the second network, and the second indication message indicates that the terminal device is in an emergency registration state. The second network decides to enter the emergency registration state based on the second indication message, thereby realizing the synchronization of the registration status of the network side and the terminal device.

[0042] In conjunction with the third aspect, in certain implementations of the third aspect, the fifth request message includes the second indication information, including: when the first network and the second network do not communicate with each other, the fifth request message includes the second indication information. According to the above technical solution, it is possible to support resolving the problem of registration status asynchrony between the network side and the terminal device.

[0043] In conjunction with the third aspect, in certain implementations of the third aspect, the first network and the second network do not communicate with each other, including: the second network is not an equivalent network of the first network, or; the first mobility management network element and the mobility management network element of the first network do not have an interface for mutual communication. According to the above technical solution, the problem of asynchronous registration status between the network side and the terminal device can be resolved.

[0044] In conjunction with the third aspect, in certain implementations of the third aspect, the method further includes: receiving third indication information from the first mobility management network element, the third indication information being used to indicate that the second network is in an emergency registration state. According to the above technical solution, it is possible to support resolving the problem of registration status asynchrony between the network side and the terminal device.

[0045] In conjunction with the third aspect, in certain implementations of the third aspect, the first network and the second network are different PLMNs. According to the above technical solution, it is possible to solve the problem of asynchronous registration status between the network side and the terminal device.

[0046] In conjunction with the third aspect, in certain implementations of the third aspect, the first network and the second network are the same PLMN with different access standards, where the access standards include any one of the following: an LTE system, a 5G system, or a NR system. According to the above technical solution, it is possible to support resolving the issue of registration status asynchrony between the network side and the terminal device.

[0047] In a fourth aspect, a communication method is provided, which is executed by a terminal device. The terminal device here may refer to the terminal device itself, or to a processor, module, chip, or chip system that implements the method in the terminal device. The method includes: emergency registration to a first network; when the session management context of the first network cannot be migrated to the second network, turning off the access standard capability of the second network, wherein the access standard capability includes any one of the following: LTE capability, NR capability, and 5G capability.

[0048] Specifically, when the first network is an LTE network, the terminal device's emergency registration with the first network can be understood as the terminal device's emergency attachment to the first network, that is, "emergency registration" can be understood as "emergency attachment." For example, the terminal device sends an Attach Request message to a mobility management network element (e.g., a mobility management entity (MME) network element) of the LTE network, and then the terminal device urgently attaches to the first network (LTE network).

[0049] It should be understood that the specific description of the emergency attachment process can be referred to the existing technology and will not be repeated here.

[0050] Specifically, when the first network is an NR network or a 5G network, the terminal device urgently registers with the first network, which can be understood as the terminal device urgently registering with the first network. For example, the terminal device sends an emergency registration request (Registration Request) message to the mobility management network element of the NR network or the 5G network (such as the access and mobility management function AMF network element), and then the terminal device urgently registers with the first network (5G network or NR network).

[0051] It should be understood that the specific description of the emergency registration process can be referred to the existing technology and will not be repeated here.

[0052] According to the above technical solution, the terminal device cannot migrate to the second network based on the session management context of the first network, and then shuts down the access standard capability of the second network, thereby achieving state synchronization between the terminal device and the network side.

[0053] In conjunction with the fourth aspect, in certain implementations of the fourth aspect, the inability to migrate the session management context of the first network to the second network includes: the second network is not an equivalent network to the first network; or the first mobility management network element and the mobility management network element of the first network lack a communication interface. The above technical solution can address the issue of registration status asynchrony between the network and the terminal device.

[0054] In conjunction with the fourth aspect, in certain implementations of the fourth aspect, disabling the access standard capability of the second network includes: disabling the LTE capability when the access standard of the second network is an LTE system; and disabling the NR capability or 5G capability when the access standard of the second network is an NR or 5G system. According to the above technical solution, it is possible to support solving the problem of registration status asynchrony between the network side and the terminal device.

[0055] In conjunction with the fourth aspect, in certain implementations of the fourth aspect, the method further includes: upon determining to terminate the emergency service, enabling the access standard capability of the second network. According to the above technical solution, the problem of registration status asynchrony between the network side and the terminal device can be solved.

[0056] In conjunction with the fourth aspect, in certain implementations of the fourth aspect, the first network and the second network are different PLMNs. According to the above technical solution, it is possible to solve the problem of asynchronous registration status between the network side and the terminal device.

[0057] In conjunction with the fourth aspect, in certain implementations of the fourth aspect, the first network and the second network are the same PLMN with different access standards, where the access standards include any one of the following: an LTE system, a 5G system, and a NR system. According to the above technical solution, it is possible to support resolving the issue of registration status asynchrony between the network side and the terminal device.

[0058] In a fifth aspect, a communication method is provided, which is executed by a first mobility management network element. The first mobility management network element here can refer to the first mobility management network element itself, or it can refer to a processor, module, chip, or chip system that implements the method in the first mobility management network element. The method includes: receiving a fourth request message from a terminal device, and the fourth request message is used to request mobile registration to a second network; sending a first response message to the terminal device, and the first response message includes first indication information, and the first indication information is used to instruct the terminal device to enter a non-emergency registration state; receiving a third request message from the terminal device, and the third registration request message is used to request initial registration to the second network.

[0059] Specifically, when the access standard of the second network is NR or 5G system, the fourth request message may be a mobility registration request message, and the first response message may be a mobility registration accept message.

[0060] Specifically, when the access standard of the second network is an LTE system, the fourth request message may be a tracking area update request message, the first response message may be a tracking area update accept message, and the session management context may be a PDN session.

[0061] In conjunction with the fifth aspect, in certain implementations of the fifth aspect, the method further includes: sending a second response message to the terminal device, the second response message being used to indicate successful initial registration with the second network. According to the above technical solution, it is possible to resolve the issue of registration status being out of sync between the network side and the terminal device.

[0062] In the sixth aspect, a communication method is provided, characterized in that the method is executed by a first mobility management network element, where the first mobility management network element can refer to the first mobility management network element itself, or can refer to a processor, module, chip, or chip system that implements the method in the first mobility management network element, and the method includes: receiving a fifth request message from a terminal device, the fifth request message being used to request to move to the second network, the fifth request message including second indication information, and the second indication information being used to indicate that the registration status of the terminal device is an emergency registration status; and determining, based on the second indication information, that the second network enters the emergency registration state.

[0063] In conjunction with the sixth aspect, in certain implementations of the sixth aspect, the method further includes: sending third indication information to the terminal device, the third indication information being used to indicate that the second network is in the emergency registration state. According to the above technical solution, it is possible to support resolving the problem of registration status asynchrony between the network side and the terminal device.

[0064] In the seventh aspect, a communication device is provided, including: a processing unit for emergency registration to a first network; the processing unit for reselecting from the first network to a second network; a transceiver unit for sending a first request message or a second request message to a first mobility management network element, wherein the first mobility management network element belongs to the second network, the first request message is used to request emergency registration to the second network, and the second request message is used to request initial registration to the second network.

[0065] In combination with the seventh aspect, in certain implementations of the seventh aspect, the transceiver unit is specifically used to: send a first request message or a second request message to the first mobility management network element when the first network and the second network do not communicate with each other.

[0066] In combination with the seventh aspect, in certain implementations of the seventh aspect, the first network and the second network do not communicate with each other, including: the second network is not an equivalent network of the first network; or the first mobility management network element and the mobility management network element of the first network do not have an interface for mutual communication.

[0067] In combination with the seventh aspect, in some implementations of the seventh aspect, the transceiver unit is specifically used to: when the terminal device executes an emergency service, send the first request message to the first mobility management network element.

[0068] In combination with the seventh aspect, in some implementations of the seventh aspect, the transceiver unit is specifically used to, including: sending the second request message to the first mobility management network element when the terminal device does not perform emergency services.

[0069] In combination with the seventh aspect, in certain implementations of the seventh aspect, before sending the first request message or the second request message to the first mobility management network element, it is characterized in that the transceiver unit is also used to: enter a deregistered state.

[0070] In combination with the seventh aspect, in certain implementations of the seventh aspect, the first network and the second network are different PLMNs.

[0071] In combination with the seventh aspect, in certain implementations of the seventh aspect, the first network and the second network are the same PLMN with different access standards, wherein the access standard includes any one of the following: LTE system, 5G system, NR system.

[0072] In the eighth aspect, a communication device is provided, including: a processing unit for emergency registration to a first network; the processing unit for reselecting from the first network to a second network; a transceiver unit for obtaining first indication information, the first indication information being used to instruct the terminal device to enter a non-emergency registration state; the transceiver unit for determining, based on the first indication information, to send a third request message to a first mobility management network element, the first mobility management network element belonging to the second network, and the third request message being used to request initial registration to the second network.

[0073] In combination with the eighth aspect, in certain implementations of the eighth aspect, before obtaining the first indication information, the transceiver unit is also used to: send a fourth request message to the first mobility management network element, and the fourth request message is used to request mobile registration to the second network; the transceiver unit is specifically used to: receive a first response message from the first mobility management network element, and the first response message includes the first indication information.

[0074] In combination with the eighth aspect, in certain implementations of the eighth aspect, the first network and the second network are different PLMNs.

[0075] In combination with the eighth aspect, in certain implementations of the eighth aspect, the first network and the second network are the same PLMN with different access standards, wherein the access standard includes any one of the following: LTE system, 5G system, NR system.

[0076] In the ninth aspect, a communication device is provided, including: a processing unit for emergency registration to a first network; the processing unit for reselecting from the first network to a second network; a transceiver unit for sending a fifth request message to a first mobility management network element, the first mobility management network element belonging to the second network, the fifth request message being used to request to move to the second network, the fifth request message including second indication information, the second indication information being used to indicate that the registration status of the terminal device is an emergency registration status.

[0077] In combination with the ninth aspect, in certain implementations of the ninth aspect, the fifth romance message includes second indication information, including: when the first network and the second network do not communicate with each other, the fifth request message includes the second indication information.

[0078] In combination with the ninth aspect, in certain implementations of the ninth aspect, the first network and the second network do not communicate with each other, including: the second network is not an equivalent network of the first network, or; the first mobility management network element and the mobility management network element of the first network do not have an interface for mutual communication.

[0079] In combination with the ninth aspect, in certain implementations of the ninth aspect, the transceiver unit is further used to: receive third indication information from the first mobility management network element, where the third indication information is used to indicate that the second network is in an emergency registration state.

[0080] In combination with the ninth aspect, in certain implementations of the ninth aspect, the first network and the second network are different PLMNs.

[0081] In combination with the ninth aspect, in certain implementations of the ninth aspect, the first network and the second network are the same PLMN with different access standards, wherein the access standard includes any one of the following: LTE system, 5G system, NR system.

[0082] In the tenth aspect, a communication device is provided, including: a processing unit for emergency registration to a first network; the processing unit is used to shut down the access standard capability of the second network when the session management context of the first network cannot be migrated to the second network, wherein the access standard capability includes any one of the following: LTE capability, NR capability, and 5G capability.

[0083] In combination with the tenth aspect, in certain implementations of the tenth aspect, the session management context of the first network cannot be migrated to the second network, including: the second network is not an equivalent network of the first network, or; the first mobility management network element and the mobility management network element of the first network do not have an interface for mutual communication.

[0084] In combination with the tenth aspect, in certain implementations of the tenth aspect, the processing unit is specifically used to: when the access standard of the second network is an LTE system, turn off the LTE capability; when the access standard of the second network is an NR or 5G system, turn off the NR capability or 5G capability.

[0085] In combination with the tenth aspect, in certain implementations of the tenth aspect, the processing unit is further used to: enable the access standard capability of the second network when it is determined that the emergency service is to be terminated.

[0086] In combination with the tenth aspect, in certain implementations of the tenth aspect, the first network and the second network are different PLMNs.

[0087] In combination with the tenth aspect, in certain implementations of the tenth aspect, the first network and the second network are the same PLMN with different access standards, wherein the access standard includes any one of the following: LTE system, 5G system, NR system.

[0088] In the eleventh aspect, a communication device is provided, including: a transceiver unit for receiving a fourth request message from a terminal device, the fourth request message being used to request mobile registration to a second network; the transceiver unit for sending a first response message to the terminal device, the first response message including first indication information, the first indication information being used to instruct the terminal device to enter a non-emergency registration state; the transceiver unit for receiving a third request message from the terminal device, the third registration request message being used to request initial registration to the second network.

[0089] In combination with the eleventh aspect, in certain implementations of the eleventh aspect, the transceiver unit is further used to: send a second response message to the terminal device, where the second response message is used to indicate successful initial registration with the second network.

[0090] In the twelfth aspect, a communication device is provided, including: a transceiver unit for receiving a fifth request message from a terminal device, the fifth request message being used to request to move to a second network, the fifth request message including second indication information, the second indication information being used to indicate that the registration status of the terminal device is an emergency registration state; a processing unit for determining, based on the second indication information, that the second network enters the emergency registration state.

[0091] In combination with the twelfth aspect, in some implementations of the twelfth aspect, the transceiver unit is further used to: send third indication information to the terminal device, where the third indication information is used to indicate that the second network is in the emergency registration state.

[0092] In the thirteenth aspect, a computer-readable storage medium is provided, on which a computer program or instruction is stored. When the computer program or instruction is executed by a processor, the method described in the first aspect and any possible implementation of the first aspect or the method described in the second aspect and any possible implementation of the second aspect is executed, or the method described in the third aspect and any possible implementation of the third aspect or the method described in the fourth aspect and any possible implementation of the fourth aspect is executed, or the method described in the fifth aspect and any possible implementation of the fifth aspect or the method described in the sixth aspect and any possible implementation of the sixth aspect is executed.

[0093] In the fourteenth aspect, a computer program product comprising instructions is provided, which, when run on a computer, causes the method described in the first aspect and any possible implementation of the first aspect, or the method described in the second aspect and any possible implementation of the second aspect, or the method described in the third aspect and any possible implementation of the third aspect, or the method described in the fourth aspect and any possible implementation of the fourth aspect, or the method described in the fifth aspect and any possible implementation of the fifth aspect, or the method described in the sixth aspect and any possible implementation of the sixth aspect to be executed.

[0094] In the fifteenth aspect, a chip system is provided, comprising: a processor for calling and running a computer program or instruction from a memory, so that a communication device equipped with the chip system implements the method as described in the first aspect and any possible implementation of the first aspect or the second aspect and any possible implementation of the second aspect or the method as described in the third aspect and any possible implementation of the third aspect or the method as described in the fourth aspect and any possible implementation of the fourth aspect or the method as described in the fifth aspect and any possible implementation of the fifth aspect or the method as described in the sixth aspect and any possible implementation of the sixth aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0095] FIG1 is a schematic diagram of a network structure applicable to an embodiment of the present application.

[0096] Figure 2 is a schematic flowchart of reselecting from a LITE network to an NR or 5G network when a UE is in emergency registration according to an embodiment of the present application.

[0097] FIG3 is a schematic flowchart of a communication method 300 provided in an embodiment of the present application.

[0098] FIG4 is a schematic flowchart of a communication method 400 provided in yet another embodiment of the present application.

[0099] FIG5 is a schematic flowchart of a communication method 500 provided in yet another embodiment of the present application.

[0100] FIG6 is a schematic flowchart of a communication method 600 provided in an embodiment of the present application.

[0101] FIG7 is a schematic flowchart of a communication method 700 provided in yet another embodiment of the present application.

[0102] FIG8 is a schematic flowchart of a communication method 800 provided in yet another embodiment of the present application.

[0103] FIG9 is a schematic flowchart of a communication method 900 provided in yet another embodiment of the present application.

[0104] FIG10 is a schematic flowchart of a communication method 1000 provided in an embodiment of the present application.

[0105] FIG11 is a schematic flowchart of a communication method 1100 provided in yet another embodiment of the present application.

[0106] FIG12 is a schematic flowchart of a communication method 1200 provided in yet another embodiment of the present application.

[0107] FIG13 is a schematic flowchart of a communication method 1300 provided in an embodiment of the present application.

[0108] FIG14 is a schematic flowchart of a communication method 1400 provided in yet another embodiment of the present application.

[0109] FIG15 is a schematic flowchart of a communication method 1500 provided in yet another embodiment of the present application.

[0110] FIG16 is a schematic block diagram of a communication device 1600 provided in an embodiment of the present application.

[0111] FIG17 shows another communication device 1700 according to an embodiment of the present application.

[0112] FIG18 shows a chip system 1800 according to an embodiment of the present application. DETAILED DESCRIPTION

[0113] The technical solution in this application will be described below with reference to the accompanying drawings.

[0114] The technical solution provided in this application can be applied to various communication systems. In a communication system, the part operated by the operator can be called a public land mobile network (PLMN) (also referred to as an operator network, etc.). A PLMN is a network established and operated by the government or an operator approved by it for the purpose of providing land mobile communication services to the public. It is mainly a public network in which mobile network operators (MNOs) provide mobile broadband access services to users. The PLMN described in this application may specifically be a network that complies with the standards of the 3rd Generation Partnership Project (3GPP), referred to as a 3GPP network. 3GPP networks generally include but are not limited to fifth-generation mobile communication (5th-generation, 5G) networks (referred to as 5G networks), fourth-generation mobile communication (4th-generation, 4G) networks (referred to as 4G networks), and other future communication systems such as 6G networks. For the sake of convenience, the embodiments of this application will be described using a 4G network or a 5G network as an example. Specifically in our country, the network of each mobile communication operator is considered a PLMN, so the networks of China Mobile, China Unicom, and China Telecom are different PLMNs.

[0115] To facilitate understanding of the embodiments of the present application, the network structure applicable to the embodiments of the present application is first described in detail with reference to FIG1 .

[0116] Figure 1 is a schematic diagram of a network structure applicable to an embodiment of the present application. As shown in Figure 1, the network structure is, for example, a network structure for intercommunication between a 5GS system and an EPS system defined by the 3rd Generation Partnership Project (3GPP). The network structure may include an access network (AN) and a core network (CN), and may also include user equipment (UE).

[0117] The access network is used to implement access-related functions. It provides network access for authorized users in a specific area and can determine transmission links of varying quality for user data transmission based on user level and service requirements. The access network forwards control signals and user data between terminal devices and the core network. The access network may include access network equipment, which can be equipment that provides access to terminal devices and may include radio access network (RAN) equipment and AN equipment. (R)AN equipment is primarily responsible for radio resource management, quality of service (QoS) management, data compression and encryption, and other functions on the air interface side. RAN equipment can include various types of base stations, such as macro base stations, micro base stations (also known as small cells), relay stations, access points, and balloon stations. In systems using different radio access technologies, the names of devices with base station functions may vary. For example, in 5G systems, they are called RAN or next-generation Node basestations (gNBs); in long-term evolution (LTE) systems, they are called evolved NodeBs (eNBs or eNodeBs).

[0118] Among them, the core network is responsible for maintaining the subscription data of the mobile network and providing UE with session management, mobility management, policy management, and security authentication functions.

[0119] The following is a brief introduction to the network elements shown in Figure 1:

[0120] 1. User equipment (UE): can be called terminal equipment, access terminal, user unit, user station, mobile station, mobile station, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication equipment, user agent or user device.

[0121] The terminal device may be a device that provides voice / data connectivity to users, such as a handheld device or vehicle-mounted device with wireless connection function. At present, some examples of terminals may include: mobile phones, tablet computers, computers with wireless transceiver functions (such as laptops, PDAs, etc.), mobile internet devices (MIDs), virtual reality (VR) devices, augmented reality (AR) devices, wireless terminals in industrial control, wireless terminals in self-driving, wireless terminals in remote medical, wireless terminals in smart grids, wireless terminals in transportation safety, wireless terminals in smart cities, wireless terminals in smart homes, cellular phones, cordless phones, session initiation protocol (SIP) phones, wireless local loop (WLL) stations, personal digital assistants (PDAs), handheld devices with wireless communication functions, computing devices or other processing devices connected to wireless modems, vehicle-mounted devices, wearable devices, terminal devices in 5G networks or future evolved public land mobile communication networks (PLMNs). terminal equipment in network, PLMN, etc.

[0122] Furthermore, terminal devices can also be end devices in the Internet of Things (IoT) system. IoT is a crucial component of future information technology development. Its primary technical feature is connecting objects to the Internet through communication technologies, thereby enabling intelligent networks that interconnect humans and machines, and objects and things. IoT technology, for example, utilizes narrowband NB technology to achieve massive connectivity, deep coverage, and power-saving terminals.

[0123] In addition, terminal devices can also include sensors such as smart printers, train detectors, and gas stations. Their main functions include collecting data (part of the terminal devices), receiving control information and downlink data from network devices, and sending electromagnetic waves to transmit uplink data to network devices.

[0124] It should be understood that the terminal device can be any device that can access the network. The terminal device and the access network device can communicate with each other using a certain air interface technology.

[0125] 2. Access Network: This includes the evolved UMTS terrestrial radio access network (E-UTRAN) in LTE systems and the next generation radio access network (NG-RAN) in 5G systems. The access network provides network access for authorized users in a specific area and includes radio access network (RAN) equipment and network access network (AN) equipment. RAN equipment is primarily 3GPP network wireless network equipment, while AN equipment can be non-3GPP defined access network equipment.

[0126] The access network may be an access network that uses different access technologies. Currently, there are two types of wireless access technologies: 3GPP access technology (such as the wireless access technology used in 3G, 4G or 5G systems) and non-3GPP access technology. 3GPP access technology refers to access technology that complies with 3GPP standards and specifications. For example, the access network equipment in the 5G system is called the next generation Node Base station (gNB) or RAN. Non-3GPP access technology refers to access technology that does not comply with 3GPP standards and specifications. For example, air interface technology represented by access points (APs) in wireless fidelity (WiFi), worldwide interoperability for microwave access (WiMAX), code division multiple access (CDMA) networks, etc. Access network equipment (AN equipment) can allow terminal devices and the 3GPP core network to interconnect and communicate using non-3GPP technologies.

[0127] The access network (RAN) is a network that implements access network functions based on wireless communication technologies. The RAN is responsible for radio resource management, quality of service (QoS) management, data compression, and encryption on the air interface side. It provides access services to terminal devices and forwards control signals and user data between them and the core network.

[0128] The wireless access network may include, for example, but is not limited to: a macro base station, a micro base station (also known as a small station), a radio network controller (RNC), a node B (NB), a base station controller (BSC), a base transceiver station (BTS), a home base station (e.g., a home evolved NodeB, or home Node B, HNB), a baseband unit (BBU), an AP in a WiFi system, a wireless relay node, a wireless backhaul node, a transmission point (TP) or a transmission and reception point (TRP), etc. It may also be a gNB or a transmission point (TRP or TP) in a 5G (e.g., NR) system, one or a group of (including multiple antenna panels) antenna panels of a base station in a 5G system, or a network node constituting a gNB or a transmission point, such as a baseband unit (BBU), or a distributed unit (DU), or a base station in a next-generation communication 6G system. The embodiments of the present application do not limit the specific technology and specific device form adopted by the wireless access network equipment.

[0129] The access network can provide services for the cell. The terminal device can communicate with the cell through the transmission resources (for example, frequency domain resources, or spectrum resources) allocated by the access network equipment.

[0130] 3. Mobility Management Entity (MME) network element: It is the network element of the EPC system core network control plane, mainly used for access control, user registration network, mobility management, session management and routing selection.

[0131] 4. Access and Mobility Management Function (AMF) network element: This is a network element in the 5GS system core network, primarily responsible for mobility and access management, such as user location updates, user network registration, and user handover. The AMF can also implement other functions in the MME beyond session management, such as lawful interception or access authorization (or authentication).

[0132] 5. Serving gateway (SGW) network element: mainly responsible for user plane processing, routing and forwarding of data packets, etc., used to process business flows and complete business carrying, etc.

[0133] 6. SMF+PGW-C Converged Network Element: A network entity formed by the session management function (SMF) and the PDN gateway control plane function (PGW-C). It is primarily used for session management, UE Internet Protocol (IP) address allocation and management, selection of endpoints for manageable user plane functions, policy control, or charging function interfaces, and downlink data notification.

[0134] 7. UPF+PGW-U Converged Network Element: This network entity is composed of the user plane function (UPF) and the PDN gateway user plane function (PGW-U). It is primarily responsible for forwarding and receiving user data in terminal devices. It can receive user data from the data network (DN) and transmit it to the terminal device through the access network equipment.

[0135] 8. HSS+UDM Converged Network Element: A network entity formed by the home subscriber server (HSS) and unified data management (UDM). It is primarily responsible for generating authentication credentials, user identification processing (such as storing and managing permanent user identities), access authorization control, and subscription data management.

[0136] 9. PCRF+PCF converged network element: A network entity formed by the policy and charging rule function (PCRF) and the policy control function (PCF).

[0137] 10. N26 interface: The interface between the AMF network element and the MME network element. It is used by the target network to obtain UE mobility management and session management information from the source network through the N26 interface in UE interoperability scenarios between 4G and 5G systems. The N26 interface is optional and its application deployment depends on the operator's specific deployment strategy and service requirements.

[0138] The network structure shown in Figure 1 supports service continuity during the interoperability between 4G and 5G systems. There is no need to change the user plane anchor point during the change from 4G to 5G or vice versa, saving service processing resources.

[0139] It should be understood that the network elements in the network structure shown in Figure 1 can also interact through other interfaces, such as the N1 interface between the AMF network element and the UE. For the sake of brevity, they are not described in detail here.

[0140] It should be understood that the above-mentioned network structure applied to the embodiment of the present application is only an example of a network structure described from the perspective of a service-oriented architecture. The network structure applicable to the embodiment of the present application is not limited to this. Any network structure that can realize the functions of the above-mentioned network elements is applicable to the embodiment of the present application.

[0141] It should also be understood that the MME, AMF, SGW, SMF+PGW-C, UPF+PGW-U, and HHS+UDM shown in Figure 1 can be understood as network elements in the core network for implementing different functions, for example, they can be combined into network slices as needed. These core network network elements can be independent devices or integrated into the same device to implement different functions. This application does not limit the specific form of the above network elements.

[0142] It should also be understood that the above naming is only defined to facilitate the distinction between different functions and should not constitute any limitation to this application. This application does not exclude the possibility of adopting other naming in 5G networks and other future networks. For example, in a 6G network, some or all of the above network elements may use the terminology in 5G, or other names may be used. The interface name between the network elements in Figure 1 is only an example. The name of the interface in the specific implementation may be other names, and this application does not make specific limitations on this. In addition, the name of the message (or signaling) transmitted between the above network elements is only an example and does not constitute any limitation on the function of the message itself.

[0143] To facilitate understanding of the technical solutions provided by the embodiments of the present application, the specific process of the UE reselecting from LTE to NR when the UE is in an emergency registration state is first described in detail in conjunction with Figure 2. Figure 2 is a schematic flow chart of the UE reselecting from the LTE network to the NR or 5G network when the UE is in an emergency registration state provided by the embodiment of the present application. As shown in Figure 2, the following steps may be specifically included.

[0144] S210, the UE urgently attaches to the LTE network (the UE has an emergency PDN bearer at this time).

[0145] S220, the UE reselects from the LTE network to the NR network.

[0146] Specifically, if the UE loses communication with the LTE network due to poor or abnormal signal conditions, the UE enters the idle state from the connected state. At this point, the UE can reselect from the LTE network to the 5G or NR network. The protocol specifies that when an emergency PDN cannot be mapped from the LTE network to the NR or 5G network, the emergency PDN bearer is released locally.

[0147] S230, the UE sends a mobility registration request message to the AMF network element.

[0148] S240, when the AMF network element does not support the N26 interface, one possible situation is that the AMF network element cannot obtain the UE context information, and may restart the identity process, authentication, and security access (security mode command, SMC) process, thereby treating the mobility registration process initiated by the UE side as a normal registration process (or initial registration process).

[0149] S250, the AMF network element sends a registration acceptance message to the UE.

[0150] In the registration process shown in Figure 2, the AMF network element sends a registration accept message to the UE. It can be considered that the NR network or 5G network allows the UE to register. At this time, the network side is in a non-emergency registration state, while the UE is still in an emergency registration state, resulting in the registration status of the network side and the UE being out of sync.

[0151] Based on this, the present application aims to provide a communication method to solve the problem of asynchronous registration status between the terminal device and the network side.

[0152] The communication method provided in this application will be described in detail below in conjunction with specific embodiments.

[0153] FIG3 is a schematic flow chart of a communication method 300 provided in an embodiment of the present application. As shown in FIG3 , the method includes at least the following steps.

[0154] S310: The terminal device urgently registers to the first network.

[0155] Specifically, when the first network is an LTE network, the emergency registration of the terminal device to the first network can be understood as the emergency attachment of the terminal device to the first network, that is, "emergency registration" can be understood as "emergency attachment". For example, in step S310, the terminal device initiates an emergency attachment process to the mobility management entity MME network element of the first network. Specifically, the terminal device sends an attachment request (Attach Request) message to the MME network element, and then the terminal device urgently attaches to the first network (LTE network). It should be understood that the specific description of the emergency attachment process can be referred to the existing technology and will not be repeated here.

[0156] In the case where the first network is an NR network or a 5G network, the terminal device urgently registers with the first network, which can be understood as the terminal device urgently registering with the first network. For example, in step S310, the terminal device initiates an emergency registration process to the access and mobility management function AMF network element of the first network. Specifically, the terminal device sends an emergency registration request (Registration Request) message to the AMF network element. Subsequently, the terminal device urgently registers with the first network (5G network or NR network). It should be understood that the specific description of the emergency registration process can refer to the existing technology and will not be repeated here.

[0157] S320: The terminal device reselects from the first network to the second network.

[0158] Specifically, after the terminal device urgently registers with the first network, the terminal device is in an emergency registration state and carries an emergency session management context. However, when the communication between the terminal device and the first network is disconnected (for example, due to factors such as poor signal or abnormal signal), the terminal device enters the idle state from the connected state. At this time, the terminal device can reselect from the first network to the second network. It should be noted that the specific process of the terminal device reselecting from the first network to the second network can be referred to the existing technology and will not be repeated here.

[0159] It should be understood that when the first network is an LTE network, the emergency session management context may be an emergency packet data network (PDN) session. When the first network is a 5G or NR network, the emergency session management context may be an emergency packet data unit (PDU) session.

[0160] Optionally, in a possible implementation manner, the first network and the second network mentioned above may be different PLMNs.

[0161] For example, the first network may be China Mobile, and the second network may be China Unicom or China Telecom.

[0162] For another example, the first network may be China Unicom, and the second network may be China Mobile or China Telecom.

[0163] For another example, the first network may be China Telecom, and the second network may be China Mobile or China Unicom.

[0164] It should be understood that the above examples are merely illustrative and this application does not limit them.

[0165] Optionally, in a possible implementation, the first network and the second network described above may be the same PLMN with different access standards, wherein the access standard may be any one of the following: LTE system, NR system, and 5G system.

[0166] For example, the first network may be a PLMN whose access standard is an LTE system, and the second network may be a PLMN whose access standard is a 5G system or a PLMN whose access standard is an NR system.

[0167] For another example, the first network may be a PLMN whose access standard is a 5G system or a PLMN whose access standard is an NR system, and the second network may be a PLMN whose access standard is an LTE system.

[0168] It should be understood that the above examples are merely illustrative and are not limiting in the embodiments of the present application.

[0169] S330, the terminal device sends a first request message or a second request message to the first mobility management network element, and accordingly, the first mobility management network element receives the first request message or the second request message.

[0170] Specifically, the first mobility management network element belongs to the second network, the first request message is used to request emergency registration with the second network, and the second request message is used to request initial registration with the second network. Wherein, the first mobility management network element belongs to the second network, which can be understood as the second network including the first mobility management network element.

[0171] It should be noted that when the second network is a 5G or NR network, the first mobility management network element is an AMF network element. Correspondingly, the first request message may be an emergency registration request message, and the second request message may be an initial registration request message.

[0172] In the case that the second network is an LTE network, the first mobility management network element is an MME network element. Correspondingly, the first request message may be an emergency attach request message, and the second request message may be an attach request message.

[0173] It is worth noting that whether the terminal device sends the first request message or the second request message to the first mobility management network element is determined by the terminal device according to whether the upper layer executes the emergency service.

[0174] Optionally, in a possible implementation, when the terminal device executes an emergency service, the terminal device sends a first request message to the first mobility management network element, and accordingly, the first mobility management network element receives the first request message, wherein the first request message is used to request emergency registration.

[0175] Exemplarily, when the second network is an NR network or a 5G network, the terminal device sends a first request message (e.g., an emergency registration request message) to the first mobility management network element (e.g., an AMF network element), and the first request message is used to request emergency registration. After the first mobility management network element receives the first request message, the second network enters the emergency registration state, and then the first mobility management network element sends a registration acceptance message #1 to the terminal device, and the registration acceptance message #1 carries emergency registration identification information. The emergency registration identification information is used to indicate that the emergency registration is successful, that is, both the terminal device and the second network enter the emergency registration state.

[0176] Exemplarily, when the second network is an LTE network, the terminal device sends a first request message (e.g., an emergency attach request message) to the first mobility management network element (e.g., an MME network element). The first request message is used to request emergency registration. After the first mobility management network element receives the first request message, the second network enters the emergency registration state. Subsequently, the first mobility management network element sends an attach accept message #1 to the terminal device. The attach accept message #1 carries emergency registration identification information. The emergency registration identification information is used to indicate that the emergency registration is successful, that is, both the terminal device and the second network enter the emergency registration state.

[0177] Optionally, in a possible implementation manner, when the terminal device does not perform emergency services, the terminal device sends a second request message to the first mobility management network element, and accordingly, the first mobility management network element receives the second request message.

[0178] Exemplarily, when the second network is an NR network or a 5G network, the second request message (e.g., an initial registration request message) is used to request initial registration. After the first mobility management network element (e.g., an AMF network element) receives the second request message, the second network enters a non-emergency registration state. Subsequently, the first mobility management network element (AMF network element) sends a registration acceptance message #2 to the terminal device. At this point, both the terminal device and the second network enter a non-emergency registration state.

[0179] For example, when the second network is an LTE network, the second request message (attach request message) is used to request emergency registration. After the first mobility management network element (MME network element) receives the second request message, the second network enters a non-emergency registration state. Subsequently, the first mobility management network element (MME network element) sends an attach accept message #2 to the terminal device. At this point, both the terminal device and the second network enter a non-emergency registration state.

[0180] Optionally, in an embodiment of the present application, the step of the terminal device sending the first request message or the second request message to the first mobility management network element is performed when the first network and the second network do not communicate with each other. The first network and the second network not communicating with each other can be understood as the following situations.

[0181] Case 1: The second network is not an equivalent network of the first network.

[0182] Exemplarily, in a possible implementation, the first network and the second network are different PLMNs.

[0183] For example, the first network may be China Mobile, and the second network may be China Unicom or China Telecom.

[0184] For another example, the first network may be China Unicom, and the second network may be China Mobile or China Telecom.

[0185] For another example, the first network may be China Telecom, and the second network may be China Mobile or China Unicom.

[0186] Exemplarily, in a possible implementation, the first network and the second network are the same PLMN with different access standards.

[0187] For example, the first network may be a PLMN whose access standard is an LTE system, and the second network may be a PLMN whose access standard is a 5G system or a PLMN whose access standard is an NR system.

[0188] For another example, the first network may be a PLMN whose access standard is a 5G system or a PLMN whose access standard is an NR system, and the second network may be a PLMN whose access standard is an LTE system.

[0189] Case 2: There is no communication interface between the first mobility management network element and the mobility management network element of the first network.

[0190] For example, neither the first mobility management network element nor the mobility management network element of the first network supports the N26 interface.

[0191] Optionally, in a possible implementation, before step S330, the method may further include: the terminal device enters a deregistration state.

[0192] Exemplarily, when the terminal device performs an emergency service, the terminal device locally deregisters, that is, the terminal device enters a deregistered state, and then sends a first request message to the first mobility management network element.

[0193] Exemplarily, when the terminal device does not perform emergency services, the terminal device locally deregisters, that is, the terminal device enters a deregistered state, and then sends a second request message to the first mobility management network element.

[0194] It should be noted that for the relevant content about the terminal device entering the deregistered state, reference can be made to the existing technology and will not be repeated here.

[0195] The specific embodiments involved in the communication method 300 described above are described in detail below with reference to FIG. 4 and FIG. 5 .

[0196] Figure 4 is a schematic flow chart of a communication method 400 provided in an embodiment of the present application. As shown in Figure 4, the method includes at least the following steps.

[0197] It should be noted in advance that the embodiment shown in FIG4 is described by taking the first network as a network with an access standard of an LTE system and the second network as a network with an access standard of a 5G or NR system as an example. Regarding the case where the first network and the second network are different PLMNs (for example, the first network is LTE PLMN1 and the second network is LTE PLMN2), reference can be made to the embodiment shown in FIG4. For the sake of simplicity, it will not be described here in detail.

[0198] S410: The UE urgently attaches to the first network.

[0199] The first network is an LTE network. For ease of understanding, the following description uniformly uses the LTE network instead of the first network.

[0200] Specifically, the UE initiates an emergency attach process to the MME of the LTE network. For example, the UE sends an emergency attach request message to the MME. Subsequently, the UE urgently attaches to the LTE network. It should be understood that the specific description of the emergency attach process can be referred to the prior art and will not be repeated here.

[0201] S420: The UE reselects from the first network to the second network.

[0202] Among them, the second network is an NR network or a 5G network. For ease of understanding, the following uniformly uses 5G network or NR network instead of the second network for description.

[0203] Specifically, after the UE urgently attaches to the LTE network, it is in the emergency registration state and carries the emergency PDN. However, if the UE loses communication with the LTE network (for example, due to poor signal or abnormal signal), the UE enters the idle state from the connected state. At this time, the UE loses the network and searches for the NR network or 5G network. The UE can reselect from the LTE network to the 5G network or NR network.

[0204] Furthermore, the terminal device sends an emergency registration request message or an initial registration request message to the AMF network element according to whether the upper layer needs to perform emergency services.

[0205] Optionally, in a possible implementation, when the terminal device executes an emergency service, the method may include:

[0206] S431, the UE sends an emergency registration request message to the AMF network element. Accordingly, the AMF network element receives the emergency registration request message, which is used to request emergency services.

[0207] S441, the AMF network element sends an emergency registration accept message to the UE, and accordingly, the UE receives the emergency registration accept message.

[0208] Specifically, the emergency registration acceptance message carries emergency registration identification information, which is used to indicate that the emergency registration of the terminal device is successful, that is, both the UE and the network side (5G network or NR network) enter the emergency registration state.

[0209] S451, UE and AMF network element successfully establish the emergency PDU process.

[0210] Specifically, the UE initiates an emergency PDU establishment process to the AMF network element. After the UE and the AMF network element successfully establish an emergency PDU, the UE can perform emergency services, such as making an emergency call. It should be noted that the specific description of the emergency PDU establishment process can be referred to the existing technology and will not be repeated here.

[0211] Optionally, before step S431, the method may further include: the UE enters a deregistered state.

[0212] Optionally, in a possible implementation, when the terminal device does not perform emergency services, the method may include:

[0213] S432, the UE sends an initial registration request message to the AMF network element, and accordingly, the AMF network element receives the initial registration request message.

[0214] S442, the AMF network element sends an initial registration accept message to the UE, and accordingly, the UE receives the initial registration accept message.

[0215] Specifically, after receiving the initial registration request message, the AMF network element sends an initial registration acceptance message to the UE, indicating that the terminal device has successfully completed the initial registration. That is, both the UE and the network side enter the non-emergency registration state.

[0216] Optionally, before step S432, the method may further include: the UE enters a deregistered state.

[0217] Figure 5 is a schematic flow chart of a communication method 500 provided in an embodiment of the present application. As shown in Figure 5, the method includes at least the following steps.

[0218] It should be noted in advance that the embodiment shown in FIG5 is described by taking the first network as a network with an access standard of 5G or NR system and the second network as a network with an access standard of LTE system as an example. Regarding the case where the first network and the second network are different PLMNs (for example, the first network is NR PLMN1 and the second network is NR PLMN2), reference can be made to the embodiment shown in FIG5. For the sake of simplicity, it is not described here in detail.

[0219] S510: The UE urgently registers with the first network.

[0220] Among them, the first network is a 5G network or a NR network. For ease of understanding, the following description will uniformly use 5G network or NR network instead of the first network.

[0221] Specifically, the UE initiates an emergency registration process to the AMF network element of the 5G network or NR network. For example, the UE sends a registration request message to the AMF network element. Subsequently, the UE urgently registers to the 5G network or NR network. It should be understood that the specific description of the emergency registration process can refer to the prior art and will not be repeated here.

[0222] S520: The UE reselects from the first network to the second network.

[0223] The second network is an LTE network. For ease of understanding, the following description uniformly uses the LTE network instead of the second network.

[0224] Specifically, after the UE urgently registers with the 5G network or NR network, it is in the emergency registration state and carries the emergency PDU. However, when the UE loses communication with the 5G network or NR network (for example, due to poor signal or abnormal signal), the UE enters the idle state from the connected state. At this time, the UE loses the network and searches for the LTE network. The UE can reselect from the 5G network or NR network to the LTE network.

[0225] Furthermore, the terminal device sends an emergency registration request message or an initial registration request message to the MME network element according to whether the upper layer needs to perform emergency services.

[0226] Optionally, in a possible implementation, when the terminal device executes an emergency service, the method may include:

[0227] S531, the UE sends an emergency attach request message to the MME network element. Correspondingly, the MME network element receives the emergency attach request message, where the emergency attach request message is used to request an emergency service.

[0228] S541: The MME network element sends an emergency attach accept message to the UE. Correspondingly, the UE receives the emergency attach accept message.

[0229] Specifically, the emergency attach accept message carries emergency registration identification information, and the emergency attach identification information is used to indicate that the UE's emergency registration is successful, that is, both the UE and the network side (LTE network) enter the emergency registration state.

[0230] S551, the UE and the MME network element successfully establish an emergency PDN.

[0231] Specifically, the UE initiates an emergency PDN establishment process with the MME. After the UE and the MME successfully establish the emergency PDN, the UE can perform emergency services, such as making an emergency call. For a detailed description of the emergency PDN establishment process, please refer to the prior art and will not be repeated here.

[0232] Optionally, before step S531, the method may further include: the UE enters a deregistered state.

[0233] Optionally, in a possible implementation, when the terminal device does not perform emergency services, the method may include:

[0234] S532: The UE sends an attach request message to the MME network element. Correspondingly, the MME network element receives the attach request message.

[0235] S542: The MME network element sends an attach accept message to the UE. Correspondingly, the UE receives the attach accept message.

[0236] Specifically, after receiving the attach request message, the MME network element sends an attach accept message to the UE, indicating that the UE has successfully completed the initial registration. That is, both the UE and the network side enter the non-emergency registration state.

[0237] Optionally, before step S532, the method may further include: the UE enters a deregistered state.

[0238] According to the above technical solution, when a terminal device is performing an emergency service, it sends a request message requesting emergency registration to the mobility management network element of the second network. After receiving the request message, the second network enters the emergency registration state. When not performing an emergency service, the terminal device sends a request message requesting initial registration to the mobility management network element of the second network. After receiving the request message, the second network enters the non-emergency registration state, thereby achieving registration status synchronization between the second network and the terminal device.

[0239] FIG6 is a schematic flow chart of a communication method 600 provided in an embodiment of the present application. As shown in FIG6 , the method may include at least the following steps.

[0240] S610: The terminal device urgently registers to the first network.

[0241] It should be noted that step S610 is similar to step S310 and will not be described in detail here for the sake of simplicity.

[0242] S620: The terminal device reselects from the first network to the second network.

[0243] It should be noted that step S620 is similar to step S320 and will not be described in detail here for the sake of simplicity.

[0244] S630, the terminal device obtains first indication information, where the first indication information is used to instruct the terminal device to enter a non-emergency registration state.

[0245] S640: The terminal device determines to send a third request message to the first mobility management network element according to the first indication information. Correspondingly, the first mobility management network element receives the third request message.

[0246] Specifically, the first mobility management network element belongs to the second network, and the third request message is used to request initial registration with the second network. After obtaining the first indication information, the terminal device actively exits the emergency registration state and then initiates the third request message to the first mobility management network element to request initial registration with the second network. The fact that the first mobility management network element belongs to the second network can be understood as meaning that the second network includes the first mobility management network element.

[0247] It should be noted that when the second network is an NR network or a 5G network, the first mobility management network element is an AMF network element. Correspondingly, the third request message can be an initial registration request message.

[0248] In the case that the second network is an LTE network, the first mobility management network element is an MME network element. Correspondingly, the third request message may be an attach request message.

[0249] Optionally, before step S630, the method may further include: the terminal device sends a fourth request message to the first mobility management network element, and accordingly, the first mobility management network element receives the fourth request message, where the fourth request message is used to request mobile registration to the second network.

[0250] The first mobility management network element sends a first response message to the terminal device. Accordingly, the terminal device receives the first response message from the first mobility management network element, where the first response message includes the first indication information.

[0251] Exemplarily, in a possible implementation, the first indication information may be non-emergency registration identification information.

[0252] Specifically, the terminal device sends a fourth request message to the first mobility management network element, requesting mobile registration to the second network. After the first mobility management network element receives the fourth request message, the second network enters a non-emergency registration state. Subsequently, the first mobility management network element sends a first response message to the terminal device, and the first response message includes non-emergency registration identification information. After obtaining the non-emergency registration identification information, the terminal device determines that the registration state of the second network is a non-emergency registration state. At this time, the terminal device actively exits the emergency registration state, and then sends a third request message to the first mobility management network element, requesting initial registration to the second network.

[0253] Exemplarily, in a possible implementation manner, the first indication information may be first identification information, and the first identification information is used to indicate that the session management context of the second network is released.

[0254] Specifically, the terminal device sends a fourth request message to the first mobility management network element, requesting mobile registration to the second network. After receiving the fourth request message, the second network enters a non-emergency registration state. Subsequently, the first mobility management network element sends a first response message to the terminal device, and the first response message includes first identification information. After obtaining the first identification information, the terminal device learns that the session management context of the second network has been released. At this time, the terminal device actively exits the emergency registration state and then sends a third request message to the first mobility management network element, requesting initial registration to the second network.

[0255] It should be noted that when the access standard of the second network is NR or 5G system, the fourth request message may be a mobility registration request message, the first response message may be a mobility registration accept message, and the session management context may be a PDU session.

[0256] When the access standard of the second network is an LTE system, the fourth request message may be a tracking area update request message, the first response message may be a tracking area update accept message, and the session management context may be a PDN session.

[0257] Optionally, in the embodiment of the present application, the step of the terminal device sending the third request message to the first mobility management network element is performed when the first network and the second network do not communicate with each other. The first network and the second network not communicating with each other can be understood as the following situations.

[0258] Case 1: The second network is not an equivalent network of the first network.

[0259] Case 2: There is no communication interface between the first mobility management network element and the mobility management network element of the first network.

[0260] It should be noted that for the specific description of Case 1 and Case 2, please refer to the previous article and will not be repeated here.

[0261] The specific embodiments involved in the communication method 600 described above are described in detail below with reference to FIG. 7 to FIG. 9 .

[0262] It should be noted in advance that the embodiments shown in Figures 7 to 9 are all described by taking the first network as an LTE network and the second network as a 5G network or an NR network as an example. Regarding the case where the first network is a 5G network or an NR network and the second network is an LTE network, or the case where the first network and the second network are different PLMNs (for example, the first network is NR PLMN1 and the second network is NR PLMN2), reference can be made to the embodiments shown in Figures 7 to 9. For the sake of simplicity, they are not described here in detail.

[0263] FIG7 is a schematic flow chart of a communication method 700 provided in an embodiment of the present application. As shown in FIG7 , the method may include at least the following steps.

[0264] S710: The UE urgently attaches to the first network.

[0265] It should be noted that step S710 is similar to step S410 and will not be described in detail here for the sake of simplicity.

[0266] S720: The UE reselects from the first network to the second network.

[0267] It should be noted that step S720 is similar to step S420 and will not be described in detail here for the sake of simplicity.

[0268] S730, the UE sends a mobility registration request message to the AMF network element, and accordingly, the AMF network element receives the mobility registration request message.

[0269] S740, the AMF network element sends a mobility registration accept message to the UE, and accordingly, the UE receives the mobility registration accept message.

[0270] Specifically, the mobility registration request message is used to request mobile registration to the 5G or NR network. After receiving the mobility registration request message, the AMF network element enters the non-emergency registration state and sends a mobility registration acceptance message to the UE. The mobility registration acceptance message carries non-emergency registration identification information, and the non-emergency registration identification information is used to indicate that the network side (such as a 5G network or NR network) is in a non-emergency registration state.

[0271] S750, after obtaining the non-emergency registration identification information, the UE locally deregisters and exits the emergency registration state.

[0272] S760, the UE sends an initial registration request message to the AMF network element, and accordingly, the AMF network element receives the initial registration request message.

[0273] S770, the AMF network element sends an initial registration accept message to the UE, and accordingly, the UE receives the initial registration accept message.

[0274] After steps S760 and S770, both the UE and the network side (e.g., 5G network or NR network) enter a non-emergency registration state.

[0275] FIG8 is a schematic flow chart of a communication method 800 provided in yet another embodiment of the present application. As shown in FIG8 , the method may include at least the following steps.

[0276] S810: The UE urgently attaches to the first network.

[0277] It should be noted that step S810 is similar to step S410 and will not be described in detail here for the sake of simplicity.

[0278] S820: The UE reselects from the first network to the second network.

[0279] It should be noted that step S820 is similar to step S420 and will not be described in detail here for the sake of simplicity.

[0280] S830: The UE determines that it is in the emergency registration state on the LTE network and the emergency PDN cannot be mapped to the NR network or the 5G network. The UE enters the deregistered state and exits the emergency attached state.

[0281] Specifically, because the emergency PDN cannot be mapped to the NR network or 5G network, according to the protocol, the emergency PDN has been released, so the UE's emergency service cannot be continued. At this time, the UE locally deregisters and directly exits the emergency registration state.

[0282] Here, "cannot be mapped" can also be understood as "cannot be migrated" or "cannot be moved". It should be understood that the embodiments of the present application do not limit this.

[0283] S840, the UE sends an initial registration request message to the AMF network element, and accordingly, the AMF network element receives the initial registration request message.

[0284] S850, the AMF network element sends an initial registration accept message to the UE, and accordingly, the UE receives the initial registration accept message.

[0285] After steps S840 and S850, both the UE and the network side (e.g., 5G network or NR network) enter a non-emergency registration state.

[0286] It should be noted that if the UE needs to perform emergency services, such as making an emergency call, the UE can also initiate an emergency PDU session establishment process after step S850. In other words, the UE can directly initiate a normal service request after the initial registration is successful and perform emergency services after the emergency PDU session is established.

[0287] FIG9 is a schematic flow chart of a communication method 900 provided in yet another embodiment of the present application. As shown in FIG9 , the method may include at least the following steps.

[0288] S910: The UE urgently attaches to the first network.

[0289] It should be noted that step S910 is similar to step S410 and will not be described in detail here for the sake of simplicity.

[0290] S920: The UE reselects from the first network to the second network.

[0291] It should be noted that step S920 is similar to step S420 and will not be described in detail here for the sake of simplicity.

[0292] S930, the UE sends a mobility registration request message to the AMF network element, and accordingly, the AMF network element receives the mobility registration request message.

[0293] S940, the AMF network element sends a mobility registration accept message to the UE, and accordingly, the UE receives the mobility registration accept message.

[0294] Specifically, both the mobility registration request message and the mobility registration accept message carry PDU session status information (PDU Session Status), wherein the mobility registration request message is used to request mobile registration to the 5G or NR network. After receiving the mobility registration request message, the AMF network element enters the non-emergency registration state and sends a mobility registration accept message to the UE.

[0295] In this embodiment, the mobility registration accept message carries first identification information, and the first identification information indicates that the PDU on the UE side is released.

[0296] S950. After obtaining the first identification information, the UE determines that it is currently in the emergency registration state but has no PDU bearer. At this time, the UE actively exits the emergency registration state and initiates the initial registration process to the AMF network element.

[0297] S960, the UE sends an initial registration request message to the AMF network element, and accordingly, the AMF network element receives the initial registration request message.

[0298] S970, the AMF network element sends an initial registration accept message to the UE, and accordingly, the UE receives the initial registration accept message.

[0299] After steps S960 and S970, both the UE and the network side (e.g., 5G network or NR network) enter a non-emergency registration state.

[0300] According to the above technical solution, the terminal device obtains the first indication information, which is used to instruct the terminal device to enter the non-emergency registration state. The terminal device initiates the initial registration process to the second network according to the first indication information, thereby achieving state synchronization between the terminal device and the second network.

[0301] FIG10 is a schematic flow chart of a communication method 1000 provided in yet another embodiment of the present application. As shown in FIG10 , the method may include at least the following steps.

[0302] S1010: The terminal device urgently registers to the first network.

[0303] It should be noted that step S1010 is similar to step S310 and will not be described in detail here for the sake of simplicity.

[0304] S1020: The terminal device reselects from the first network to the second network.

[0305] It should be noted that step S1020 is similar to step S320 and will not be described here for the sake of simplicity.

[0306] S1030: The terminal device sends a fifth request message to the first mobility management network element. Correspondingly, the first mobility management network element receives the fifth request message.

[0307] Specifically, the first mobility management network element belongs to the second network, and the fifth request message is used to request mobile registration to the second network. The fifth request message includes second indication information, and the second indication information is used to indicate that the registration status of the terminal device is an emergency registration status. After receiving the second indication information, the first mobility management network element learns that the registration status of the terminal device is an emergency registration status, and the second network decides to enter the emergency registration status. For example, the second network can directly enter the emergency registration status without performing the authentication AUTH process, identity process, etc.

[0308] Exemplarily, the second indication information may be emergency registration identification information, and the emergency registration identification information is used to identify that the registration status of the terminal device is an emergency registration status.

[0309] The first mobility management network element mentioned above belongs to the second network, which can also be understood as the second network including the first mobility management network element.

[0310] It should be noted that when the second network is an NR network or a 5G network, the first mobility management network element is an AMF network element. Correspondingly, the fifth request message may be a mobility registration request message.

[0311] In the case that the second network is an LTE network, the first mobility management network element is an MME network element. Correspondingly, the fifth request message may be a tracking area update request message.

[0312] Optionally, in a possible implementation, the method may further include: the first mobility management network element sends third indication information to the terminal device, and accordingly, the terminal device receives the third indication information, where the third indication information is used to indicate that the second network is in an emergency registration state.

[0313] Optionally, the third indication information may be included in the registration acceptance message #3. That is, the first mobility management network element sends a registration acceptance message #3 to the terminal device, and the registration acceptance message #3 carries the third indication information.

[0314] Optionally, in the embodiment of the present application, the step of the terminal device sending the fifth request message to the first mobility management network element is performed when the first network and the second network do not communicate with each other. The first network and the second network not communicating with each other can be understood as the following situations.

[0315] Case 1: The second network is not an equivalent network of the first network.

[0316] Case 2: There is no communication interface between the first mobility management network element and the mobility management network element of the first network.

[0317] It should be noted that for the specific description of Case 1 and Case 2, please refer to the previous article and will not be repeated here.

[0318] The specific embodiments involved in the communication method 1000 described above are described in detail below with reference to FIG. 11 and FIG. 12 .

[0319] It should be noted in advance that the embodiments shown in Figures 11 and 12 are all described by taking the first network as an LTE network and the second network as a 5G or NR network as an example. Regarding the case where the first network is a 5G network or an NR network and the second network is an LTE network, or the case where the first network and the second network are different PLMNs (for example, the first network is NR PLMN1 and the second network is NR PLMN2), reference can be made to the embodiments shown in Figures 11 and 12. For the sake of simplicity, they are not described here in detail.

[0320] FIG11 is a schematic flow chart of a communication method 1100 provided in an embodiment of the present application. As shown in FIG11 , the method may include at least the following steps.

[0321] S1110 , the UE urgently attaches to the first network.

[0322] It should be noted that step S1110 is similar to step S410 and will not be described here for simplicity.

[0323] S1120. The UE reselects from the first network to the second network.

[0324] It should be noted that step S1120 is similar to step S420 and will not be described here for the sake of simplicity.

[0325] S1130, the UE sends a mobility registration request message to the AMF network element, and accordingly, the AMF network element receives the mobility registration request message.

[0326] Specifically, the mobility registration request message is used to request mobile registration to the second network (e.g., a 5G network or an NR network). The mobility registration request message includes emergency registration identification information, which is used to identify that the registration state of the UE is an emergency registration state.

[0327] S1140: After the AMF network element receives the emergency registration identification information and learns that the registration status of the terminal device is the emergency registration state, the network side (e.g., 5G network or NR network) decides to enter the emergency registration state based on the emergency registration identification information. For example, the second network can directly enter the emergency registration state without performing the AUTH process, identity process, etc.

[0328] S1150, the AMF network element sends a mobility registration accept message to the UE, and accordingly, the UE receives the mobility registration accept message.

[0329] Specifically, both the network side (such as 5G network or NR network) and the UE side enter the emergency registration state.

[0330] FIG12 is a schematic flow chart of a communication method 1200 provided in yet another embodiment of the present application. As shown in FIG12 , the method may include at least the following steps.

[0331] S1210: The UE urgently attaches to the first network.

[0332] It should be noted that step S1210 is similar to step S410 and will not be described here for the sake of simplicity.

[0333] S1220. The UE reselects from the first network to the second network.

[0334] It should be noted that step S1220 is similar to step S420 and will not be described here for the sake of simplicity.

[0335] S1230, the UE sends a mobility registration request message to the AMF network element, and accordingly, the AMF network element receives the mobility registration request message.

[0336] Specifically, the link establishment reason value carried in the mobility registration request message is the emergency registration (EMC) type. The network side (5G network or NR network) finds that the mobility registration process is initiated for emergency services based on the link establishment reason value carried by the mobility registration request message center. The network side (5G network or NR network) can decide on its own not to reject the UE and directly enter the emergency registration state.

[0337] S1240, the AMF network element sends a mobility registration accept message to the UE, and accordingly, the UE receives the mobility registration accept message.

[0338] Specifically, the mobility registration accept message includes emergency registration identification information, and the emergency registration identification information is used to identify that the network side is in an emergency registration state.

[0339] According to the above technical solution, the terminal device sends a second indication message to the mobility management network element of the second network, and the second indication message indicates that the terminal device is in an emergency registration state. The second network decides to enter the emergency registration state based on the second indication message, thereby realizing the synchronization of the registration status of the network side and the terminal device.

[0340] FIG13 is a schematic flowchart of a communication method 1300 provided in yet another embodiment of the present application. As shown in FIG13 , the method may include at least the following steps.

[0341] S1310: The terminal device urgently registers to the first network.

[0342] It should be noted that step S1310 is similar to step S310 and is not described here for simplicity.

[0343] In step S1320, if the session management context of the first network cannot be migrated to the second network, the terminal device disables the access standard capability of the second network. Here, "cannot be migrated" can be understood as "cannot be mapped" or "cannot be moved." It should be understood that this embodiment of the present application does not limit this.

[0344] Specifically, the access standard capability can be any one of 5G capability, NR capability, and LTE capability.

[0345] It should be noted that the session management context of the first network cannot be migrated to the second network, which can be understood as the following two situations.

[0346] Case 1: There is no communication interface between the first mobility management network element and the mobility management network element of the first network.

[0347] For example, there is no N26 interface between the first mobility management network element and the mobility management network element of the first network, or both the first mobility management network element and the mobility management network element of the first network do not support the N26 interface.

[0348] Case 2: The second network is not an equivalent network of the first network.

[0349] Exemplarily, in a possible implementation, the first network and the second network mentioned above may be different PLMNs.

[0350] For example, the first network may be China Mobile, and the second network may be China Unicom or China Telecom.

[0351] For another example, the first network may be China Unicom, and the second network may be China Mobile or China Telecom.

[0352] For another example, the first network may be China Telecom, and the second network may be China Mobile or China Unicom.

[0353] For example, in one possible implementation, the first network and the second network described above may be the same PLMN with different access standards, wherein the access standard may be any one of the following: LTE system, NR system, or 5G system.

[0354] For example, the first network may be a PLMN whose access standard is an LTE system, and the second network may be a PLMN whose access standard is a 5G system or a PLMN whose access standard is an NR system.

[0355] For another example, the first network may be a PLMN whose access standard is a 5G system or a PLMN whose access standard is an NR system, and the second network may be a PLMN whose access standard is an LTE system.

[0356] It should be understood that the above examples are merely illustrative and are not limiting in the embodiments of the present application.

[0357] It should be noted that, when the access standard of the first network is an LTE system, the session management context of the first network cannot be migrated to the second network. This can be understood as the EPS bearer of the first network cannot be migrated to the second network. Here, "cannot be migrated" can be understood as "cannot be mapped" or "cannot be moved". It should be understood that this embodiment of the present application does not limit this.

[0358] For example, when the access standard of the second network is an LTE system, when the terminal device determines that the EPS bearer of the first network cannot be migrated to the second network (LTE system), the terminal device turns off the LTE capability.

[0359] For example, when the access standard of the second network is the NR system, when the terminal device determines that the EPS bearer of the first network cannot be migrated to the second network (NR system), the terminal device turns off the NR capability.

[0360] It should also be noted that when the access standard of the first network is an NR or 5G system, the session management context of the first network cannot be migrated to the second network. This can be understood as the PDU session of the first network cannot be migrated to the second network. Here, "cannot be migrated" can be understood as "cannot be mapped" or "cannot be moved". It should be understood that this embodiment of the present application does not limit this.

[0361] Exemplarily, when the access standard of the second network is an LTE system, when the terminal device determines that the PDU session of the first network cannot be migrated to the second network (LTE system), the terminal device turns off the LTE capability.

[0362] For example, when the access standard of the second network is the NR system, when the terminal device determines that the PDU session of the first network cannot be migrated to the second network (NR system), the terminal device turns off the NR capability.

[0363] It should be understood that the aforementioned disabling of LTE capability can be understood as "Disable LTE", and disabling of NR capability can be understood as "Disable NR". Among them, "disabling" can also mean "prohibiting" or "blocking", which is not limited in the embodiments of the present application.

[0364] Optionally, in a possible implementation manner, the method may further include: when the terminal device determines to terminate the emergency service, enabling the access standard capability of the second network.

[0365] Exemplarily, when the access standard of the second network is an LTE system, when the terminal device determines to end the emergency service, the terminal device turns on the LTE capability.

[0366] For example, when the access standard of the second network is the NR system, when the terminal device determines to end the emergency service, the terminal device turns on the NR capability.

[0367] It should be understood that the aforementioned enabling of LTE capabilities can be understood as "Enable LTE", and disabling of NR capabilities can be understood as "Enable NR". "Enable" can also mean "allow" or "execute", which is not limited in the present embodiment.

[0368] The specific embodiments involved in the communication method 1300 described above are described in detail below with reference to FIG. 14 and FIG. 15 .

[0369] FIG14 is a schematic flow chart of a communication method 1400 provided in an embodiment of the present application. As shown in FIG14 , the method may include the following steps.

[0370] It should be noted in advance that the embodiment shown in Figure 14 is described as an example in which the first network is a network with an access standard of an LTE system and the second network is a network with an access standard of a 5G or NR system. Regarding the case where the first network and the second network are different PLMNs (for example, the first network is LTE PLMN1 and the second network is LTE PLMN2), reference can be made to the embodiment shown in Figure 14. For the sake of simplicity, this will not be described in detail here.

[0371] S1410 , the UE sends an emergency PDN establishment request message to the MME network element, and accordingly, the MME network element receives the emergency PDN establishment request message.

[0372] S1420 , the MME network element sends a response message indicating that the emergency PDN is successfully established to the UE. Correspondingly, the UE receives the response message indicating that the emergency PDN is successfully established.

[0373] Optionally, the response message indicating that the emergency PDN is successfully established does not carry PDU mapping information of the second network (e.g., a 5G network or an NR network).

[0374] S1430: When the EPS of the LTE network cannot be migrated to the NR network or the 5G network, the UE disables the 5G capability or the NR capability.

[0375] S1440, the UE sends a tracking area update request message to the MME network element, and accordingly, the MME network element receives the tracking area update request message.

[0376] Specifically, the tracking area update request message carries indication information, which indicates that the UE does not support 5G or NR capabilities. Among them, "UE does not support 5G or NR capabilities" can be understood as that the UE can only reselect and switch within the LTE network, and cannot reselect or switch to the 5G or NR network.

[0377] S1450, the MME network element sends a tracking area update accept message to the UE, and accordingly, the UE receives the tracking area update accept message.

[0378] FIG15 is a schematic flowchart of a communication method 1500 provided in an embodiment of the present application. As shown in FIG15 , the method may include the following steps.

[0379] It should be noted in advance that the embodiment shown in Figure 15 is described by taking the first network as a network with an access standard of 5G or NR system and the second network as a network with an access standard of LTE system as an example. Regarding the case where the first network and the second network are different PLMNs (for example, the first network is NR PLMN1 and the second network is NR PLMN2), reference can be made to the embodiment shown in Figure 15. For the sake of simplicity, it is not described here in detail.

[0380] S1510, the UE sends an emergency PDU establishment request message to the AMF network element, and accordingly, the AMF network element receives the emergency PDU establishment request message.

[0381] S1520, the AMF network element sends a response message to the UE indicating that the emergency PDU is successfully established. Correspondingly, the UE receives a response message indicating that the emergency PDU is successfully established.

[0382] Optionally, the response message indicating that the emergency PDU is successfully established does not carry PDN mapping information of the second network (eg, LTE network).

[0383] S1530: When the PDU of the NR or 5G network cannot be migrated to the LTE network, the UE disables the LTE capability.

[0384] S1540, the UE sends a mobility registration request message to the AMF network element, and accordingly, the AMF network element receives the mobility registration request message.

[0385] Specifically, the mobility registration request message carries indication information indicating that the UE does not support LTE capabilities. Here, "UE does not support LTE capabilities" can be understood as meaning that the UE can only reselect or switch within the 5G or NR network, and cannot reselect or switch to the LTE network.

[0386] S1550, the AMF network element sends a mobility registration accept message to the UE, and accordingly, the UE receives the mobility registration accept message.

[0387] According to the above technical solution, the terminal device cannot migrate to the second network based on the session management context of the first network, and then shuts down the access standard capability of the second network, thereby achieving state synchronization between the terminal device and the network side.

[0388] It should be understood that some optional features in the embodiments of the present application may not depend on other features in some scenarios, and may also be combined with other features in some scenarios, without limitation.

[0389] It can also be understood that the solutions in the various embodiments of the present application can be reasonably combined and used, and the explanations or descriptions of the various terms appearing in the embodiments can be referenced or explained with each other in the various embodiments, without limitation to this.

[0390] It can also be understood that the sizes of the various numerical serial numbers in the embodiments of the present application do not mean the order of execution, but are only distinguished for the convenience of description and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0391] It can also be understood that in the various embodiments of the present application, some message names are involved, such as mobility registration request message or initial registration request message, etc. It should be understood that their naming does not limit the protection scope of the embodiments of the present application.

[0392] It can also be understood that in each of the above-mentioned method embodiments, the methods and operations implemented by the terminal device can also be implemented by the components of the terminal device (such as chips or circuits); in addition, the methods and operations implemented by the first mobility management network element can also be implemented by the components of the first mobility management network element (such as chips or circuits), without limitation. Corresponding to the methods given in the above-mentioned method embodiments, the embodiments of the present application also provide corresponding communication devices, which include modules for executing the corresponding modules of the above-mentioned method embodiments. The module can be software, hardware, or a combination of software and hardware. It can be understood that the technical features described in the above-mentioned method embodiments are also applicable to the following device embodiments.

[0393] It should be understood that the terminal device and the first mobility management network element may perform some or all of the steps in the above embodiments. These steps or operations are merely examples, and the embodiments of the present application may also perform other operations or variations of various operations. In addition, the various steps may be performed in a different order than those presented in the above embodiments, and it is possible that not all of the operations in the above embodiments need to be performed.

[0394] The communication method provided in the embodiment of the present application is described in detail above in conjunction with Figures 3 to 15 . The communication device provided in the embodiment of the present application is described in detail below in conjunction with Figures 16 to 18 . It should be understood that the description of the device embodiment corresponds to the description of the method embodiment. Therefore, for matters not described in detail, reference can be made to the method embodiment above. For the sake of brevity, some contents are not repeated here.

[0395] Figure 16 is a schematic block diagram of a communication device provided in an embodiment of the present application. The device 1600 includes a transceiver unit 1610, which can be used to implement corresponding communication functions. The transceiver unit 1610 can also be called a communication interface or a communication unit.

[0396] Optionally, the device 1600 may further include a processing unit 1620 , which may be configured to perform data processing.

[0397] Optionally, the device 1600 also includes a storage unit, which can be used to store instructions and / or data, and the processing unit 1620 can read the instructions and / or data in the storage unit so that the device implements the actions of different terminal devices in the aforementioned method embodiments, for example, the actions of the terminal device and the first mobility management network element.

[0398] The device 1600 can be used to execute the actions performed by the terminal device or the first mobility management network element in the above method embodiments. In this case, the device 1600 can be a terminal device or a first mobility management network element, or a component of the terminal device or the first mobility management network element. The transceiver unit 1610 is used to execute the operations related to the transmission and reception of the terminal device or the first mobility management network element in the above method embodiments, and the processing unit 1620 is used to execute the operations related to the processing of the terminal device or the first mobility management network element in the above method embodiments.

[0399] Exemplarily, the terminal device may be a UE, and the first mobility management network element may be an AMF network element or an MME network element.

[0400] It should also be understood that the device 1600 here is embodied in the form of a functional unit. The term "unit" here may refer to an application specific integrated circuit (ASIC), an electronic circuit, a processor (such as a shared processor, a dedicated processor or a group processor, etc.) and a memory for executing one or more software or firmware programs, a combined logic circuit and / or other suitable components that support the described functions. In an optional example, those skilled in the art will understand that the device 1600 may be specifically the terminal device or the first mobility management network element in the above-mentioned embodiment, and may be used to execute the various processes and / or steps corresponding to the terminal device or the first mobility management network element in the above-mentioned method embodiments, or the device 1600 may be specifically the terminal device or the first mobility management network element in the above-mentioned embodiment, and may be used to execute the various processes and / or steps corresponding to the terminal device or the first mobility management network element in the above-mentioned method embodiments. To avoid repetition, they will not be described here.

[0401] The apparatus 1600 of each of the above-mentioned solutions has the function of implementing the corresponding steps executed by the terminal device or the first mobility management network element in the above-mentioned method, or the apparatus 1600 of each of the above-mentioned solutions has the function of implementing the corresponding steps executed by the terminal device or the first mobility management network element in the above-mentioned method. The functions can be implemented by hardware, or can be implemented by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above-mentioned functions; for example, the transceiver unit can be replaced by a transceiver (for example, the sending unit in the transceiver unit can be replaced by a transmitter, and the receiving unit in the transceiver unit can be replaced by a receiver), and other units, such as the processing unit, can be replaced by a processor to respectively perform the sending and receiving operations and related processing operations in each method embodiment.

[0402] In addition, the transceiver unit 1610 may also be a transceiver circuit (for example, may include a receiving circuit and a transmitting circuit), and the processing unit may be a processing circuit.

[0403] It should be noted that the apparatus in FIG16 may be a network element or device in the aforementioned embodiment, or may be a chip or chip system, such as a system on chip (SoC). The transceiver unit may be an input / output circuit or a communication interface; the processing unit may be a processor, microprocessor, or integrated circuit integrated on the chip. This is not limited here.

[0404] As shown in Figure 17, an embodiment of the present application provides another communication device 1700. The device 1700 includes a processor 1710, which is coupled to a memory 1720. The memory 1720 is used to store computer programs or instructions and / or data. The processor 1710 is used to execute the computer programs or instructions stored in the memory 1720, or read the data stored in the memory 1720, to perform the methods in the above method embodiments.

[0405] Optionally, there are one or more processors 1710 .

[0406] Optionally, the memory 1720 is one or more.

[0407] Optionally, the memory 1720 is integrated with the processor 1710 or provided separately.

[0408] Optionally, as shown in Figure 17, the device 1700 further includes a transceiver 1730, which is used to receive and / or send signals. For example, the processor 1710 is used to control the transceiver 1730 to receive and / or send signals.

[0409] As a solution, the apparatus 1700 is used to implement the operations performed by the terminal device or the first mobility management network element in the above various method embodiments.

[0410] For example, the processor 1710 is configured to execute a computer program or instruction stored in the memory 1720 to implement the relevant operations of the terminal device or the first mobility management network element in each of the above method embodiments. For example, the terminal device in any one of the embodiments shown in Figures 3 to 15, or the method of the first mobility management network element in any one of the embodiments shown in Figures 3 to 15.

[0411] It should be understood that the processor mentioned in the embodiments of the present application may be a central processing unit (CPU), or may be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc.

[0412] It should also be understood that the memory mentioned in the embodiments of the present application may be a volatile memory and / or a non-volatile memory. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM). For example, RAM can be used as an external cache. By way of example and not limitation, RAM includes the following forms: static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct rambus RAM (DR RAM).

[0413] It should be noted that when the processor is a general-purpose processor, DSP, ASIC, FPGA or other programmable logic device, discrete gate or transistor logic device, discrete hardware component, the memory (storage module) can be integrated into the processor.

[0414] It should also be noted that the memory described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0415] As shown in FIG18 , an embodiment of the present application provides a chip system 1800 . The chip system 1800 (or also referred to as a processing system) includes a logic circuit 1810 and an input / output interface 1820 .

[0416] Logic circuit 1810 may be a processing circuit within chip system 1800. Logic circuit 1810 may be coupled to a storage unit and invoke instructions within the storage unit, enabling chip system 1800 to implement the methods and functions of various embodiments of the present application. Input / output interface 1820 may be an input / output circuit within chip system 1800, outputting information processed by chip system 1800 or inputting data or signaling information to be processed into chip system 1800 for processing.

[0417] As a solution, the chip system 1800 is used to implement the operations performed by the terminal device or the first mobility management network element in the above various method embodiments.

[0418] For example, the logic circuit 1810 is used to implement the processing-related operations by the terminal device in the above method embodiments, such as the processing-related operations of the first mobility management network element in any one of the embodiments shown in Figures 3 to 15; the input / output interface 1820 is used to implement the sending and / or receiving-related operations by the terminal device in the above method embodiments, such as the sending and / or receiving-related operations performed by the first mobility management network element in any one of the embodiments shown in Figures 3 to 15.

[0419] An embodiment of the present application further provides a computer-readable storage medium storing computer instructions for implementing the methods executed by the terminal device or the first mobility management network element in the above-mentioned method embodiments.

[0420] For example, when the computer program is executed by a computer, the computer can implement the method performed by the terminal device or the first mobility management network element in each embodiment of the above method.

[0421] An embodiment of the present application further provides a computer program product comprising instructions, which, when executed by a computer, implement the methods performed by the terminal device or the first mobility management network element in the above-mentioned method embodiments.

[0422] The explanation of the relevant contents and beneficial effects of any of the above-mentioned devices can be referred to the corresponding method embodiments provided above, which will not be repeated here.

[0423] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0424] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0425] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0426] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0427] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0428] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0429] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A communication method, characterized in that: include: Emergency registration to the First Network; reselecting from the first network to a second network; Send a first request message or a second request message to a first mobility management network element, where the first mobility management network element belongs to the second network, the first request message is used to request emergency registration to the second network, and the second request message is used to request initial registration to the second network.

2. The method according to claim 1, characterized in that The sending the first request message or the second request message to the first mobility management network element includes: In a case where the first network and the second network do not communicate with each other, a first request message or a second request message is sent to a first mobility management network element.

3. The method according to claim 2, characterized in that The first network and the second network do not communicate with each other, including: The second network is not an equivalent network of the first network; or, The first mobility management network element and the mobility management network element of the first network do not have an interface for mutual communication.

4. The method according to any one of claims 1 to 3, characterized in that The sending the first request message or the second request message to the first mobility management network element includes: When the terminal device performs emergency services, the first request message is sent to the first mobility management network element.

5. The method according to any one of claims 1 to 3, characterized in that The sending the first request message or the second request message to the first mobility management network element includes: When the terminal device does not perform emergency services, the second request message is sent to the first mobility management network element.

6. The method according to any one of claims 1 to 5, characterized in that Before sending the first request message or the second request message to the first mobility management network element, the method further includes: Enter the deregistration state.

7. A communication method, characterized in that: include: Emergency registration to the First Network; reselecting from the first network to a second network; Acquire first indication information, where the first indication information is used to instruct the terminal device to enter a non-emergency registration state; According to the first indication information, it is determined to send a third request message to a first mobility management network element, where the first mobility management network element belongs to the second network, and the third request message is used to request initial registration with the second network.

8. The method according to claim 7, characterized in that Before obtaining the first indication information, the method further includes: Sending a fourth request message to the first mobility management network element, where the fourth request message is used to request mobile registration to the second network; The obtaining of the first indication information includes: A first response message is received from the first mobility management network element, where the first response message includes the first indication information.

9. The method according to any one of claims 1 to 3, characterized in that The first network and the second network are different public land mobile communication networks PLMN.

10. The method according to any one of claims 1 to 4, characterized in that The first network and the second network are the same PLMN with different standards, The format includes any one of the following: Long Term Evolution LTE system, fifth-generation 5G system, and new wireless NR system.

11. A communication method, characterized in that: The method comprises: Emergency registration to the First Network; reselecting from the first network to a second network; A fifth request message is sent to a first mobility management network element, where the first mobility management network element belongs to the second network. The fifth request message is used to request to move to the second network. The fifth request message includes second indication information, and the second indication information is used to indicate that the registration status of the terminal device is an emergency registration status.

12. The method according to claim 11, characterized in that The fifth request message includes second indication information, including: In a case where the first network and the second network do not communicate with each other, the fifth request message includes second indication information.

13. The method according to claim 12, characterized in that The first network and the second network do not communicate with each other, including: The second network is not an equivalent network of the first network, or; The first mobility management network element and the mobility management network element of the first network do not have an interface for mutual communication.

14. The method according to any one of claims 11 to 13, characterized in that The method further comprises: Receive third indication information from the first mobility management network element, where the third indication information is used to indicate that the second network is in an emergency registration state.

15. A communication method, characterized in that: The method comprises: Emergency registration to the First Network; If the session management context of the first network cannot be migrated to the second network, disable the access standard capability of the second network, where the access standard capability includes any one of the following: LTE capabilities, NR capabilities, and 5G capabilities.

16. The method according to claim 15, characterized in that The session management context of the first network cannot be migrated to the second network, including: The second network is not an equivalent network of the first network, or; The first mobility management network element and the mobility management network element of the first network do not have an interface for mutual communication.

17. The method according to claim 15 or 16, characterized in that The disabling the access standard capability of the second network includes: When the access standard of the second network is an LTE system, disabling LTE capability; When the access standard of the second network is NR or 5G system, the NR capability or 5G capability is turned off.

18. The method according to any one of claims 15 to 17, characterized in that The method further comprises: When it is determined that the emergency service is to be terminated, the access standard capability of the second network is enabled.

19. The method according to any one of claims 1 to 18, characterized in that The first network and the second network are different PLMNs.

20. The method according to any one of claims 1 to 18, characterized in that The first network and the second network are the same PLMN with different access standards, The access mode includes any one of the following: LTE system, 5G system, NR system.

21. A communication method, characterized in that: include: receiving a fourth request message from the terminal device, where the fourth request message is used to request mobile registration to the second network; Sending a first response message to the terminal device, where the first response message includes first indication information, where the first indication information is used to instruct the terminal device to enter a non-emergency registration state; A third request message is received from the terminal device, where the third registration request message is used to request initial registration with the second network.

22. The method according to claim 21, characterized in that The method further comprises: A second response message is sent to the terminal device, where the second response message is used to indicate successful initial registration with the second network.

23. A communication method, characterized in that: include: receiving a fifth request message from a terminal device, where the fifth request message is used to request to move to a second network, the fifth request message including second indication information, where the second indication information is used to indicate that the registration state of the terminal device is an emergency registration state; According to the second indication information, it is determined that the second network enters the emergency registration state.

24. The method according to claim 23, wherein The method further comprises: Send third indication information to the terminal device, where the third indication information is used to indicate that the second network is in the emergency registration state.

25. A communication device, characterized in that: Comprising a unit for performing the method described in any one of claims 1 to 6, or comprising a unit for performing the method described in any one of claims 7 to 10, or comprising a unit for performing the method described in any one of claims 11 to 14, or comprising a unit for performing the method described in any one of claims 15 to 20.

26. A communication device, characterized in that: The method comprises a unit for executing the method of claims 21 and 22, or a unit for executing the method of any one of claims 23 and 24.

27. A computer-readable storage medium having a computer program or instruction stored thereon, characterized in that: When the computer program or instructions are executed by a processor, the method according to any one of claims 1 to 6 is executed, or the method according to any one of claims 7 to 10 is executed, or the method according to any one of claims 1 to 6 is executed, or the method according to any one of claims 1 to 6 is executed, or the method according to any one of claims 11 to 14 is executed, or the method according to any one of claims 15 to 20 is executed, or the method according to claims 21 and 22 is executed, or the method according to claims 23 and 24 is executed.

28. A computer program product comprising instructions which, when run on a computer, causes the method of any one of claims 1 to 6 to be performed, or the method of any one of claims 7 to 10 to be performed, or the method of any one of claims 1 to 6 to be performed, or the method of any one of claims 1 to 6 to be performed, or the method of any one of claims 11 to 14 to be performed, or the method of any one of claims 15 to 20 to be performed, or the method of claims 21 and 22 to be performed, or the method of claims 23 and 24 to be performed.

29. A chip system, characterized in that: include: A processor for calling and running a computer program or instruction from a memory so that a communication device equipped with the chip system implements the method as described in any one of claims 1 to 6 or implements the method as described in any one of claims 7 to 10 or implements the method as described in any one of claims 11 to 14 or implements the method as described in any one of claims 15 to 20 or implements the methods as described in claims 21 and 22 or implements the methods as described in claims 23 and 24.

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