CN116567761A

CN116567761A - Communication method and device

Info

Publication number: CN116567761A
Application number: CN202210114807.2A
Authority: CN
Inventors: 金辉; 窦凤辉; 薛祎凡
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2022-01-30
Filing date: 2022-01-30
Publication date: 2023-08-08
Also published as: WO2023142777A1

Abstract

The application provides a communication method and a communication device, relates to the technical field of wireless communication, can avoid the problem of TAU failure, is beneficial to shortening the network disconnection time of terminal equipment and reducing the power consumption of the terminal equipment. The method comprises the following steps: the second network element determines that a third public land mobile network PLMN serving the terminal device belongs to the first PLMN, wherein the second network element is a network element in the PLMN to which the terminal device belongs, and the number of the first PLMNs is at least one and is different from that of the PLMN to which the terminal device belongs. The second network element does not send the first target parameter to the terminal device, or the second network element sends indication information to the terminal device, wherein the indication information indicates that the first target parameter is deleted. The first target parameter comprises a parameter mapping of a protocol data unit, PDU, session of a first communication scheme to a parameter of a second communication scheme.

Description

Communication method and device

Technical Field

The embodiment of the application relates to the field of wireless communication, in particular to a communication method and device.

Background

Currently, when a terminal device in an idle (idle) state moves from a fifth generation (5G) network to a fourth generation (fourth generation, 4G) network, if at least one PDU session supporting interworking exists in one protocol data unit (protocol data unit, PDU) session established on the terminal device, the terminal device initiates a tracking area update (tracking area update, TAU) request in the 4G network. If the PDU session of the terminal device stores the corresponding 4G parameter, it can be understood that the PDU session is a PDU session supporting interoperability. Correspondingly, a core network element mobility management entity (mobility management entity, MME) of the 4G network acquires context information of the terminal equipment from a core network element access and mobility management function (access and mobility management function, AMF) of the 5G network, thereby completing TAU.

However, in roaming scenarios, the session management function element (session management function, SMF) element of the home network always sends the terminal device the 4G parameters corresponding to the PDU session. And when an interface is not opened between the AMF network element of the visiting network side and the MME network element of the home network side, if the terminal equipment moves from the 5G network of the visiting network to the 4G network of the home network, the MME cannot acquire the context information, so that TAU fails, the power consumption and the off-network time of the terminal equipment are increased, and the user experience is poor.

Disclosure of Invention

The embodiment of the application provides a communication method and device, which can avoid the problem of TAU failure, and is beneficial to shortening the network disconnection time of terminal equipment and reducing the power consumption of the terminal equipment.

In order to achieve the above purpose, the embodiment of the application adopts the following technical scheme:

in a first aspect, the present application provides a communication method, where the execution body of the method may be the second network element, or may be a chip applied in the second network element. The following describes an example in which the execution body is the second network element. The method comprises the following steps: the second network element determines that a third public land mobile network PLMN serving the terminal device belongs to the first PLMN, wherein the second network element is a network element in the PLMN to which the terminal device belongs, and the number of the first PLMNs is at least one and is different from that of the PLMN to which the terminal device belongs. The second network element does not send the first target parameter to the terminal device, or the second network element sends indication information to the terminal device, wherein the indication information indicates that the first target parameter is deleted. The first target parameters comprise parameters of a protocol data unit PDU session of a first communication system mapped to parameters of a second communication system, the communication system of a third PLMN providing service for the terminal equipment comprises the first communication system, the communication system of the PLMN to which the terminal equipment belongs comprises the second communication system, and the first communication system is different from the second communication system.

In this way, in the case that the third PLMN for providing services to the terminal device belongs to the first PLMN, the terminal device will not receive the first target parameter, or delete the received first target parameter. When the terminal equipment reselects from the third PLMN of the first communication system which currently provides service for the terminal equipment to the PLMN of the second communication system which belongs to the terminal equipment, the terminal equipment does not initiate TAU any more because the terminal equipment does not store the first target parameter, so that the problem of TAU failure is avoided, the network disconnection time of the terminal equipment is shortened, and the power consumption of the terminal equipment is reduced.

In one possible design, the communication method of the embodiment of the application further includes: the second network element receives first information from a third mobility management entity, wherein the third mobility management entity is a network element in a third PLMN for providing services for the terminal device, and the first information includes information of an operator to which the third mobility management entity belongs. The second network element determining that a third PLMN serving the terminal device belongs to the first PLMN, comprising: the second network unit determines, according to the first information, that a third PLMN providing service for the terminal equipment belongs to the first PLMN.

That is, the second network element may determine that the third PLMN for providing services for the terminal device belongs to the first PLMN based on information of an operator to which the third mobility management entity belongs.

In one possible design, the second network element determines that a third PLMN serving the terminal device belongs to the first PLMN, including: when the second network unit determines that the terminal device is in the roaming state, the second network unit determines that a third PLMN for providing services for the terminal device belongs to the first PLMN, so as to simplify the processing procedure of the second network unit.

In one possible design, the communication method of the embodiment of the application further includes: the second network element receives second information from a third network element or a third border gateway BG, where the third network element is a network element in a third PLMN that provides services for the terminal device, and the third BG is configured to connect the second network element and the third network element. And the second network unit determines that the terminal equipment is in a roaming state according to the second information.

That is, the second network element can receive information from the third network element or the third border gateway, i.e. the terminal device can be considered to be in a roaming state.

In one possible design, the communication method of the embodiment of the application further includes: the second network element sends a PDU session establishment acceptance message to the terminal device. Wherein the second network element does not send the first target parameter to the terminal device, comprising: the PDU session establishment accept message does not carry the first target parameter, and accordingly, the terminal device cannot receive the first target parameter.

In one possible design, the second network element sends the indication information to the terminal device via a PDU session modification command message to provide the indication information to the terminal device during the session modification procedure.

In one possible design, the first PLMN is preconfigured.

In one possible design, the communication method of the embodiment of the application further includes: the second network element determines that the fourth PLMN serving the terminal device does not belong to the first PLMN. The second network unit sends second target parameters to the terminal equipment, wherein the second target parameters comprise parameters of PDU (protocol data unit) session of a first communication system mapped to parameters of the second communication system, and the communication system of a fourth PLMN for providing service for the terminal equipment comprises the first communication system, so that the terminal equipment can normally acquire the second target parameters. It should be appreciated that for the first target parameter, the PDU session of the first communication system is the PDU session in the third PLMN in the first target parameter. For the second target parameter, the PDU session of the first communication system is a PDU session in the fourth PLMN in the second target parameter.

In one possible design, the fourth PLMN serving the terminal device is the terminal device home PLMN. That is, the PLMN to which the terminal device is currently accessing is the PLMN to which it belongs.

In one possible design, the fourth PLMN serving the terminal equipment is different from the country to which the operator of the PLMN to which the terminal equipment belongs. That is, the terminal device is in a foreign roaming state.

In one possible design, the second network element determines that the fourth PLMN serving the terminal device does not belong to the first PLMN, including: when the second network unit determines that the terminal device is in the roaming state, the second network unit determines that the fourth PLMN for providing services for the terminal device does not belong to the first PLMN, so as to simplify the processing procedure of the second network unit.

In one possible design, the communication method of the embodiment of the application further includes: the second network element receives fourth information from a fourth network element or a fourth border gateway BG, where the fourth network element is a network element in a fourth PLMN for providing services for the terminal device, and the fourth BG is configured to connect the second network element and the fourth network element. And the second network unit determines that the terminal equipment is in a roaming state according to the fourth information. That is, the second network element can receive information from the fourth network element or fourth border gateway, i.e. the terminal device can be considered to be in a roaming state.

In one possible design, the communication method of the embodiment of the application further includes: the second network element receives first information from a fourth mobility management entity, wherein the fourth mobility management entity is a network element in a fourth PLMN for providing services for the terminal device, and the first information includes information of an operator to which the fourth mobility management entity belongs. The second network element determining that a fourth PLMN serving the terminal device is not part of the first PLMN, comprising: the second network unit determines that the fourth PLMN for providing service for the terminal equipment does not belong to the first PLMN according to the first information.

That is, the second network element may determine that the fourth PLMN for providing services to the terminal device does not belong to the first PLMN based on information of an operator to which the fourth mobility management entity belongs.

In one possible design, the first information includes a globally unique access and mobility management function identification, GUAMI.

In a second aspect, the present application provides a communication method, where the execution body of the method may be the second network element, or may be a chip applied in the second network element. The following describes an example in which the execution body is the second network element. The method comprises the following steps: the second network element determines that the public land mobile network PLMN serving the terminal equipment does not belong to the first PLMN, wherein the second network element is a network element in the terminal equipment home PLMN, and the number of the first PLMNs is at least one and different from the terminal equipment home PLMN. The second network unit sends target parameters to the terminal equipment, wherein the target parameters comprise parameters of a protocol data unit PDU session of a first communication system mapped to parameters of a second communication system, the communication system of the PLMN for providing service for the terminal equipment comprises the first communication system, the communication system of the PLMN to which the terminal equipment belongs comprises the second communication system, and the first communication system is different from the second communication system.

That is, in case the public land mobile network PLMN serving the terminal equipment does not belong to the first PLMN, the second network element can provide the target parameters for the terminal equipment so that the terminal equipment normally acquires the target parameters.

In one possible design, the PLMN serving the terminal device is the terminal device home PLMN.

In one possible design, the PLMN serving the terminal device is different from the country to which the operator of the PLMN to which the terminal device belongs.

In one possible design, the second network element determines that the PLMN serving the terminal device does not belong to the first PLMN, comprising: when the second network element determines that the terminal device is in the roaming state, the second network element determines that the PLMN serving the terminal device does not belong to the first PLMN.

In one possible design, the communication method of the embodiment of the application further includes: the second network element receives first information from a first network element or a border gateway BG, where the first network element is a network element in a PLMN providing services for the terminal device, and the BG is configured to connect the first network element and the second network element. The second network unit determines that the terminal equipment is in a roaming state according to the first information.

In one possible design, the communication method of the embodiment of the application further includes: the second network element receives second information from the first mobility management entity, wherein the first mobility management entity is a network element in a PLMN serving the terminal device, and the second information includes information of an operator to which the first mobility management entity belongs. The second network element determining that the PLMN serving the terminal device is not of the first PLMN, comprising: and the second network unit determines that the PLMN providing the service for the terminal equipment does not belong to the first PLMN according to the second information.

In one possible design, the second information includes a globally unique access and mobility management function identification, GUAMI.

In one possible design, the first PLMN is preconfigured.

In a third aspect, the present application provides a communication method, where the execution body of the method may be a terminal device, or may be a chip applied in the terminal device. The following describes an example in which the execution subject is a terminal device. The method comprises the following steps: when the terminal equipment moves from a first communication mode of a first Public Land Mobile Network (PLMN) to a second communication mode of a PLMN to which the terminal equipment belongs, a registration request message is sent to a second mobile management entity of the PLMN to which the terminal equipment belongs, wherein the first PLMN is different from the PLMN to which the terminal equipment belongs, the first communication mode is different from the second communication mode, the terminal equipment stores target parameters, and the target parameters comprise parameters of a Protocol Data Unit (PDU) session of the first communication mode mapped to parameters of the second communication mode. The terminal device receives a registration accept message from the second mobility management entity.

When the terminal device moves from the first communication system of the first PLMN to the second communication system of the PLMN to which the terminal device belongs, if the terminal device moves in the idle state, the terminal device reselects from the first communication system of the first PLMN to the second communication system of the PLMN to which the terminal device belongs. If the terminal equipment moves in the connected state, the terminal equipment is switched from a first communication mode of the first PLMN to a second communication mode of the PLMN to which the terminal equipment belongs.

Thus, even if the first PLMN is different from the PLMN to which the terminal equipment belongs, and the terminal equipment stores the target parameters, when the terminal equipment moves from the first communication system of the first PLMN to the second communication system of the PLMN to which the terminal equipment belongs, the terminal equipment also initiates the registration request message and does not initiate the TAU any more, so that the problem of TAU failure is avoided, the network disconnection time of the terminal equipment is shortened, and the power consumption of the terminal equipment is reduced.

In one possible design, the communication method of the embodiment of the application further includes: and the terminal equipment determines that the first PLMN is different from the home PLMN of the terminal equipment according to the first information. The first information includes information of at least one third PLMN, which is different from the home PLMN of the terminal equipment, and the third PLMN includes the first PLMN.

That is, the first information includes information of at least one third PLMN that is preconfigured. In this way, the terminal device determines, based on the first information, that the first PLMN and the terminal device home PLMN are different.

In one possible design, the communication method of the embodiment of the application further includes: the terminal device receives the first information from the second mobility management entity to obtain the first information from the second mobility management entity of the home network.

In one possible design, the first information is carried in the same message as the equivalent public land mobile network EPLMN. Wherein the EPLMN comprises at least a first PLMN. That is, the terminal device may acquire the first information during the registration process of the home network, so that when the terminal device reselects from the first communication system of the first PLMN to the second communication system of the home PLMN of the terminal device, the registration request message may be initiated in time, thereby effectively avoiding the problem of TAU failure.

In one possible design, the communication method of the embodiment of the application further includes: the terminal device receives first information from a second network element, wherein the second network element belongs to a network element in a PLMN to which the terminal device belongs, so as to acquire the first information from the second network element.

In one possible design, the terminal device receives the first information from the second network element via a PDU session establishment accept message. That is, the terminal device may acquire the first information during the PDU session establishment process, so that when the terminal device reselects from the first communication system of the first PLMN to the second communication system of the PLMN to which the terminal device belongs, the registration request message may be initiated in time, thereby effectively avoiding the problem of TAU failure.

In a fourth aspect, the present application provides a communication method, where the execution body of the method may be a terminal device, or may be a chip applied in the terminal device. The following describes an example in which the execution subject is a terminal device. The method comprises the following steps: the terminal device sends a registration request message to a first mobility management entity of a first public land mobile network PLMN, wherein the first PLMN is different from a home PLMN of the terminal device. The terminal device receives a registration accept message from the first mobility management entity. The terminal device deletes the target parameter, or the terminal device does not generate the target parameter, or does not store the target parameter when the terminal device receives the target parameter from the second network unit, wherein the second network unit is a network unit in the PLMN to which the terminal device belongs, the target parameter comprises a parameter of a protocol data unit PDU session of a first communication system mapped to a parameter of a second communication system, the communication system of the first PLMN comprises the first communication system, and the communication system of the PLMN to which the terminal device belongs comprises the second communication system.

That is, even if the first PLMN is different from the home PLMN of the terminal device, and the terminal device has deleted the target parameter after the first PLMN registration, or does not generate the target parameter, or does not save the target parameter when the terminal device receives the target parameter from the second network element. In this way, when the terminal equipment reselects from the first communication system of the first PLMN to the second communication system of the PLMN to which the terminal equipment belongs, the terminal equipment initiates the registration request message and does not initiate the TAU any more because the terminal equipment does not save the target parameters, thereby avoiding the problem of TAU failure, being beneficial to shortening the network disconnection time of the terminal equipment and reducing the power consumption of the terminal equipment.

In one possible design, the communication method of the embodiment of the application further includes: the terminal device receives the first information from a second mobility management entity, wherein the second mobility management entity is a network element in the PLMN to which the terminal device belongs.

In one possible design, the first information is carried in the same message as the equivalent public land mobile network EPLMN. Wherein the EPLMN comprises at least a first PLMN.

In one possible design, the communication method of the embodiment of the application further includes: the terminal device receives first information from a second network element, wherein the second network element belongs to a network element in a home PLMN of the terminal device.

In one possible design, the terminal device receives the first information from the second network element via a PDU session establishment accept message.

In a fifth aspect, the present application provides a communication device, which may be the second network element in the first aspect or any one of the possible designs of the first aspect, or a chip implementing the function of the second network element; the communication device comprises corresponding modules, units or means (means) for realizing the method, and the modules, units or means can be realized by hardware, software or realized by executing corresponding software by hardware. The hardware or software includes one or more modules or units corresponding to the functions described above.

The communication device includes a processing unit, a transmitting unit, and a receiving unit. The processing unit is configured to determine that a third public land mobile network PLMN serving the terminal device belongs to a first PLMN, where the communication device is a network element in a PLMN to which the terminal device belongs, and the number of the first PLMNs is at least one and is different from the PLMN to which the terminal device belongs. A transmitting unit, which is not used for transmitting the first target parameter to the terminal equipment, or is used for transmitting indication information to the terminal equipment, wherein the indication information indicates that the first target parameter is deleted; the first target parameters comprise parameters of a protocol data unit PDU session of a first communication system mapped to parameters of a second communication system, the communication system of a third PLMN providing service for the terminal equipment comprises the first communication system, the communication system of the PLMN to which the terminal equipment belongs comprises the second communication system, and the first communication system is different from the second communication system.

In one possible design, the receiving unit is configured to receive first information from a third mobility management entity, where the third mobility management entity is a network element in a third PLMN that provides a service for the terminal device, and the first information includes information of an operator to which the third mobility management entity belongs. A processing unit, configured to determine that a third PLMN for providing services for a terminal device belongs to the first PLMN, includes: according to the first information, it is determined that a third PLMN providing service for the terminal equipment belongs to the first PLMN.

In one possible design, the processing unit is configured to determine that a third PLMN for providing services for the terminal device belongs to the first PLMN, and includes: when the terminal device is determined to be in the roaming state, it is determined that the third PLMN providing service for the terminal device belongs to the first PLMN.

In one possible design, the receiving unit is further configured to receive the second information from a third network element or a third border gateway BG, where the third network element is a network element in a third PLMN that provides services for the terminal device, and the third BG is configured to connect the communication device and the third network element. And the processing unit is also used for determining that the terminal equipment is in a roaming state according to the second information.

In one possible design, the sending unit is further configured to send a PDU session establishment accept message to the terminal device. Wherein the sending unit, which is not used for sending the first target parameter to the terminal device, includes: the PDU session establishment acceptance message does not carry the first target parameter.

In one possible design, the sending unit is configured to send the indication information to the terminal device through a PDU session modification command message.

In one possible design, the first PLMN is preconfigured.

In one possible design, the processing unit is further configured to determine that the fourth PLMN for providing services to the terminal device does not belong to the first PLMN. The sending unit is further configured to send a second target parameter to the terminal device, where the second target parameter includes a parameter of a PDU session of the first communication system mapped to a parameter of the second communication system, and a communication system of a fourth PLMN for providing services for the terminal device includes the first communication system.

In one possible design, the fourth PLMN serving the terminal device is the terminal device home PLMN.

In one possible design, the fourth PLMN serving the terminal equipment is different from the country to which the operator of the PLMN to which the terminal equipment belongs.

In one possible design, the processing unit is configured to determine that the fourth PLMN for providing services to the terminal device does not belong to the first PLMN, and includes: when the terminal device is determined to be in the roaming state, it is determined that the fourth PLMN providing service for the terminal device does not belong to the first PLMN.

In one possible design, the receiving unit is further configured to receive fourth information from a fourth network element or a fourth border gateway BG, where the fourth network element is a network element in a fourth PLMN for providing services to the terminal device, and the fourth BG is configured to connect the communication device and the fourth network element. And the processing unit is further used for determining that the terminal equipment is in the roaming state according to the fourth information.

In one possible design, the receiving unit is further configured to receive first information from a fourth mobility management entity, where the fourth mobility management entity is a network element in a fourth PLMN that provides services for the terminal device, and the first information includes information of an operator to which the fourth mobility management entity belongs. A processing unit, configured to determine that a fourth PLMN for providing services for the terminal device does not belong to the first PLMN, includes: according to the first information, it is determined that the fourth PLMN serving the terminal equipment does not belong to the first PLMN.

In a sixth aspect, the present application provides a communication device, which may be the second network element in the second aspect or any one of the possible designs of the second aspect, or a chip implementing the function of the second network element; the communication device comprises corresponding modules, units or means (means) for realizing the method, and the modules, units or means can be realized by hardware, software or realized by executing corresponding software by hardware. The hardware or software includes one or more modules or units corresponding to the functions described above.

The communication device includes a processing unit, a transmitting unit, and a receiving unit. The processing unit is configured to determine that a public land mobile network PLMN serving the terminal equipment does not belong to a first PLMN, where the communication device is a network element in a PLMN to which the terminal equipment belongs, and the number of the first PLMNs is at least one and is different from the PLMN to which the terminal equipment belongs. The terminal equipment comprises a sending unit, a receiving unit and a receiving unit, wherein the sending unit is used for sending target parameters to the terminal equipment, the target parameters comprise parameters of a protocol data unit PDU session of a first communication system mapped to parameters of a second communication system, the communication system of a PLMN for providing service for the terminal equipment comprises the first communication system, the communication system of the PLMN to which the terminal equipment belongs comprises the second communication system, and the first communication system is different from the second communication system.

In one possible design, the processing unit is configured to determine that a PLMN serving the terminal device does not belong to the first PLMN, and includes: when the terminal device is determined to be in the roaming state, it is determined that the PLMN serving the terminal device does not belong to the first PLMN.

In one possible configuration, the receiving unit is further configured to receive first information from a first network element or a border gateway BG, wherein the first network element is a network element in a PLMN serving the terminal device, and the BG is configured to connect the first network element and the communication device. And the processing unit is also used for determining that the terminal equipment is in a roaming state according to the first information.

In a possible design, the receiving unit is further configured to receive second information from a first mobility management entity, where the first mobility management entity is a network element in a PLMN that serves the terminal device, and the second information includes information of an operator to which the first mobility management entity belongs. A processing unit, configured to determine that a PLMN for providing services for a terminal device does not belong to a first PLMN, includes: and according to the second information, determining that the PLMN providing the service for the terminal equipment does not belong to the first PLMN.

In one possible design, the first PLMN is preconfigured.

In a seventh aspect, the present application provides a communication device, which may be a terminal device in any one of the above-mentioned third aspect or any one of the possible designs of the third aspect, or a chip for implementing the function of the above-mentioned terminal device; the communication device comprises corresponding modules, units or means (means) for realizing the method, and the modules, units or means can be realized by hardware, software or realized by executing corresponding software by hardware. The hardware or software includes one or more modules or units corresponding to the functions described above.

The communication device includes a processing unit, a transmitting unit, and a receiving unit. The processing unit is used for determining a second communication system from a first communication system of a first Public Land Mobile Network (PLMN) to a communication device attribution PLMN, and controlling the sending unit to send a registration request message to a second mobile management entity of the communication device attribution PLMN, wherein the first PLMN is different from the communication device attribution PLMN, the first communication system is different from the second communication system, the communication device stores target parameters, and the target parameters comprise parameters of a Protocol Data Unit (PDU) session of the first communication system mapped to parameters of the second communication system. The processing unit is further configured to control the receiving unit to receive a registration accept message from the second mobility management entity.

In one possible design, the processing unit is further configured to determine, based on the first information, that the first PLMN is different from the home PLMN of the communication device. The first information includes information of at least one third PLMN, which is different from the home PLMN of the communication device, and the third PLMN includes the first PLMN.

In a possible design, the receiving unit is further configured to receive the first information from the second mobility management entity.

In one possible design, the receiving unit is further configured to receive the first information from a second network element, wherein the second network element belongs to a network element in the PLMN to which the communication device belongs.

In one possible design, the receiving unit is configured to receive the first information from the second network element via a PDU session establishment accept message.

In an eighth aspect, the present application provides a communication device, which may be a terminal device in any one of the possible designs of the fourth aspect or the fourth aspect, or a chip for implementing the functions of the terminal device; the communication device comprises corresponding modules, units or means (means) for realizing the method, and the modules, units or means can be realized by hardware, software or realized by executing corresponding software by hardware. The hardware or software includes one or more modules or units corresponding to the functions described above.

The communication device includes a processing unit, a transmitting unit, and a receiving unit. The sending unit is configured to send a registration request message to a first mobility management entity of a first public land mobile network PLMN, where the first PLMN is different from a home PLMN of the communication device. A receiving unit, configured to receive a registration acceptance message from the first mobility management entity. The processing unit is used for deleting the target parameter, or is used for not generating the target parameter, or is used for not storing the target parameter when the receiving unit is used for receiving the target parameter from the second network unit, wherein the second network unit is a network unit in the PLMN to which the communication device belongs, the target parameter comprises parameters of a protocol data unit PDU session of a first communication system mapped to parameters of a second communication system, the communication system of the first PLMN comprises the first communication system, and the communication system of the PLMN to which the communication device belongs comprises the second communication system.

In one possible design, the receiving unit is further configured to receive the first information from a second mobility management entity, wherein the second mobility management entity is a network element in a PLMN to which the communication device belongs.

In a ninth aspect, embodiments of the present application provide a communication apparatus, including: a processor and a memory; the memory is configured to store computer instructions that, when executed by the processor, cause the communication device to perform the method performed by the second network element in any one of the above aspects or any one of the possible designs. The communication device may be the second network element in the above-mentioned first aspect or any of the possible designs of the first aspect, or the communication device may be the second network element in the above-mentioned second aspect or any of the possible designs of the second aspect, or a chip implementing the functions of the second network element.

In a tenth aspect, embodiments of the present application provide a communication apparatus, including: a processor; the processor is coupled to the memory for reading the instructions in the memory and executing to cause the communication device to perform the method performed by the second network element in any one of the above aspects or any one of the possible designs. The communication device may be the second network element in the above-mentioned first aspect or any of the possible designs of the first aspect, or the communication device may be the second network element in the above-mentioned second aspect or any of the possible designs of the second aspect, or a chip implementing the functions of the second network element.

In an eleventh aspect, embodiments of the present application provide a chip including a processing circuit and an input-output interface. Wherein the input-output interface is for communication with a module outside the chip, which may be, for example, a chip implementing the functionality of the second network element in the first aspect or any of the possible designs of the first aspect. The processing circuitry is arranged to run a computer program or instructions to implement the method of the first aspect above or any of the possible designs of the first aspect. As another example, the chip may be a chip implementing the functionality of the second network element in the second aspect or any of the possible designs of the second aspect. The processing circuitry is configured to run a computer program or instructions to implement the method of the second aspect above or any of the possible designs of the second aspect.

In a twelfth aspect, embodiments of the present application provide a communication apparatus, including: a processor and a memory; the memory is for storing computer instructions which, when executed by the processor, cause the communications apparatus to perform the method performed by the terminal device in any one of the above aspects or any one of the possible designs of any one of the aspects. The communication means may be a terminal device in any one of the possible designs of the third aspect or the third aspect, or the communication means may be a terminal device in any one of the possible designs of the fourth aspect or the fourth aspect, or a chip implementing the functions of the terminal device.

In a thirteenth aspect, embodiments of the present application provide a communication device, including: a processor; the processor is coupled to the memory for reading the instructions in the memory and executing the instructions to cause the communication device to perform the method performed by the terminal device as in any one of the above aspects or any one of the possible designs of the aspect. The communication means may be a terminal device in any one of the possible designs of the third aspect or the third aspect, or the communication means may be a terminal device in any one of the possible designs of the fourth aspect or the fourth aspect, or a chip implementing the functions of the terminal device.

In a fourteenth aspect, embodiments of the present application provide a chip including a processing circuit and an input-output interface. Wherein the input-output interface is for communication with a module outside the chip, which may be, for example, a chip implementing the functionality of the terminal device in any of the above-mentioned third aspects or any of the possible designs of the third aspect. The processing circuitry is arranged to run a computer program or instructions to implement the method of any one of the above third aspects or any one of the possible designs of the third aspect. As another example, the chip may be a chip implementing the functions of the terminal device in any of the above-mentioned fourth or fourth possible designs. The processing circuitry is arranged to run a computer program or instructions to implement the method in any of the above fourth or any of the possible designs of the fourth aspect.

In a fifteenth aspect, embodiments of the present application provide a computer-readable storage medium having instructions stored therein that, when run on a computer, cause the computer to perform the method of any one of the above aspects.

In a sixteenth aspect, embodiments of the present application provide a computer program product comprising instructions which, when run on a computer, cause the computer to perform the method of any one of the above aspects.

In a seventeenth aspect, embodiments of the present application provide circuitry comprising processing circuitry configured to perform the method of any one of the above aspects.

The technical effects of any one of the designs of the fifth to seventeenth aspects may refer to the advantages of the corresponding methods provided above, and are not repeated herein.

Drawings

Fig. 1 is a schematic architecture diagram of a communication system applied in an embodiment of the present application;

FIG. 2 is a schematic architecture diagram of yet another communication system to which embodiments of the present application are applied;

FIG. 3 is a schematic architecture diagram of yet another communication system to which embodiments of the present application apply;

FIG. 4 is a schematic architecture diagram of yet another communication system to which embodiments of the present application apply;

FIG. 5 is a schematic diagram of an architecture of yet another communication system to which embodiments of the present application apply;

fig. 6 is a schematic flow chart of a communication method according to an embodiment of the present application;

fig. 7 is a flow chart of still another communication method according to an embodiment of the present application;

fig. 8a is a flow chart of another communication method according to an embodiment of the present application;

fig. 8b is a flowchart of another communication method according to an embodiment of the present application;

Fig. 9 is a flow chart of another communication method according to an embodiment of the present application;

fig. 10a is a flow chart of another communication method according to an embodiment of the present application;

fig. 10b is a flowchart of another communication method according to an embodiment of the present application;

fig. 11 is a flow chart of another communication method according to an embodiment of the present application;

fig. 12 is a flow chart of another communication method according to an embodiment of the present application;

fig. 13 is a flow chart of another communication method according to an embodiment of the present application;

fig. 14 is a schematic structural diagram of a communication device according to an embodiment of the present application;

fig. 15 is a schematic structural diagram of still another communication device according to an embodiment of the present application.

Detailed Description

Fig. 1 is a schematic architecture diagram of a communication system according to an embodiment of the present application. As shown in fig. 1, the communication system includes a terminal device, an access network device, and a core network.

The terminal device comprises a device for providing voice and/or data connectivity to a user, specifically, a device for providing voice to a user, a device for providing data connectivity to a user, or a device for providing voice and data connectivity to a user. For example, may include a handheld device having wireless connectivity, or a processing device connected to a wireless modem. The terminal device may communicate with the core network via a radio access network (radio access network, RAN), exchange voice or data with the RAN, or interact voice and data with the RAN. The terminal device may include a User Equipment (UE), a wireless terminal device, a mobile terminal device, a device-to-device (D2D) terminal device, a vehicle-to-device (V2X) terminal device, a machine-to-machine/machine-type communication (M2M/MTC) terminal device, an internet of things (internet of things, ioT) terminal device, a subscription unit (subscriber unit), a subscription station (subscriber station), a mobile station (mobile station), a remote station, an Access Point (AP), a remote terminal (remote terminal), an access terminal (access terminal), a user terminal (user terminal), a user agent (user agent), or a user equipment (user device), etc. For example, mobile telephones (or "cellular" telephones) computers with mobile terminal devices, portable, pocket, hand-held, computer-built mobile devices, and the like may be included. Such as personal communication services (personal communication service, PCS) phones, cordless phones, session initiation protocol (session initiation protocol, SIP) phones, wireless local loop (wireless local loop, WLL) stations, personal digital assistants (personal digital assistant, PDAs), and the like. But also limited devices such as devices with lower power consumption, or devices with limited memory capabilities, or devices with limited computing capabilities, etc. Examples include bar codes, radio frequency identification (radio frequency identification, RFID), sensors, global positioning systems (global positioning system, GPS), laser scanners, and other information sensing devices.

While the various terminal devices described above, if located on a vehicle (e.g., placed in a vehicle or mounted in a vehicle), may be considered as in-vehicle terminal devices, for example, also referred to as in-vehicle units (OBUs).

In the embodiment of the application, the terminal device may further include a relay (relay). Or it is understood that all that is capable of data communication with a base station can be seen as a terminal device.

In the embodiment of the present application, the device for implementing the function of the terminal device may be the terminal device, or may be a device capable of supporting the terminal device to implement the function, for example, a chip system, and the device may be installed in the terminal device. In the embodiment of the application, the chip system may be formed by a chip, and may also include a chip and other discrete devices. In the technical solution provided in the embodiment of the present application, an apparatus for implementing a function of a terminal is taken as an example of a terminal device, and description is made.

The access network device may be an access point for wireless communication or wired communication, such as a base station or a base station controller, a wireless-fidelity (wifi) access point or a wifi controller, or a fixed network access point, etc. The base stations may include various types of base stations, for example: micro base stations (also referred to as small stations), macro base stations, relay stations, access points, etc., as embodiments of the present application are not specifically limited. In the embodiment of the present application, the base station may be a base station (base transceiver station, BTS) in a global system for mobile communications (global system for mobile communication, GSM), a base station (base transceiver station, BTS) in a code division multiple access (code division multiple access, CDMA), a base station (node B) in a wideband code division multiple access (wideband code division multiple access, WCDMA), an evolved base station (evolutional node B, eNB or e-NodeB) in a long term evolution (long term evolution, LTE), an eNB in the internet of things (internet of things, ioT) or a narrowband internet of things (narrow band-internet of things, NB-IoT), a base station in a fifth generation (the fifth generation, 5G) mobile communication network or a public land mobile network (public land mobile network, PLMN) of future evolution, which is not limited in any way by the embodiments of the present application.

The core network includes various core network devices, such as an access management network element, a session management network element, and the like. The access management network element is mainly used for mobility management, access management and the like, and can be used for realizing other functions besides session management, such as legal interception, access authorization/authentication and the like, in the functions of the mobility management entity (mobility management entity, MME). In a 5G communication system, the access management network element may comprise an access and mobility management function (core access and mobility management function, AMF) network element. The session management network element is mainly used for session management, network interconnection protocol (internet protocol, IP) address allocation and management of terminal equipment, terminal node for selecting manageable user plane functions, policy control and charging function interfaces, downlink data notification and the like. In a fifth generation (the fifth generation, 5G) communication system, the session management network element may comprise a session management function (session management function, SMF) network element. The MME may refer to the description of fig. 2, and the AMF network element and the SMF network element may refer to the description of fig. 3. It should be understood that the core network device may also include other network elements, such as a user plane function (user plane function, UPF) network element, etc., which will not be described in detail herein.

By way of example, fig. 2 shows a schematic architecture of a fourth generation (the fourth generation, 4G) communication system. The 4G communication system includes network elements or devices such as evolved universal mobile telecommunications system (universal mobile telecommunications system, UMTS) terrestrial radio access network (evolved UMTS territorial radio access network, E-UTRAN) devices, MME, serving Gateway (SGW), packet data network (packet data network, PDN) Gateway (PGW), policy and charging rules function (policy and charging rules function, PCRF) network elements, and home subscriber server (home subscriber server, HSS).

The terminal equipment accesses the E-UTRAN equipment through LTE-Uu, the E-UTRAN equipment communicates with MME through S1-MME, the E-UTRAN equipment communicates with SGW through S1-U, different MME communicates with HSS through S10 (only one MME is shown in an exemplary way in fig. 2), MME communicates with HSS through S6a, MME communicates with SGW through S11, PGW communicates with PCRF network element through Gx, PCRF network element communicates with server through Rx, SGW communicates with PGW through S5, and PGW accesses server through SGi.

Wherein the E-UTRAN equipment is used for realizing the functions related to the evolution network wireless. The MME is responsible for mobility management of a control plane, including user context and mobility state management, allocation of user temporary identity, and the like. SGW is a third generation partnership project (3rd generation partnership project,3GPP) inter-access network user plane anchor and is an interface to terminate E-TURAN. PGW is a user plane anchor point between 3GPP access network and non-3 GPP access network, and is an interface for termination and external PDN. The PCRF network element is used for policy control decision and flow charging control functions. The HSS is used to store subscriber subscription information. The server is used to provide internet protocol (internet protocol, IP) services such as voice/video services based on internet protocol multimedia subsystem (internet protocol multimediasubsystem, IMS), packet switched streaming services (packet switched streaming service, PSS), etc.

By way of example, fig. 3 shows a schematic architecture of a 5G communication system. The 5G communication system includes a radio access network (radio access network, RAN) device, a user plane function (user plane function, UPF) network element, an AMF network element, an SMF network element, an authentication server function (authentication server function, AUSF) network element, a network slice selection function (network slice selection function, NSSF) network element, a network opening function (network exposure function, NEF) network element, a network function storage function (network exposure function repository function, NRF) network element, a policy control function (policy control function, PCF) network element, a unified data management (unified data management, UDM) network element, a unified data storage (unified data repository, UDR) network element, an application function (application function, AF) network element, or a billing function (charging function, CHF) network element, etc.

It should be noted that fig. 3 is only an example given as to some network elements or entities in the 5G communication system, and the 5G communication system may further include some network elements or entities not shown in fig. 3, such as network data analysis function (network data analytics function, NWDAF) network elements, which are not specifically limited in this embodiment of the present application.

As shown in fig. 3, the terminal device accesses the 5G network through the RAN device, and the terminal device communicates with the AMF through an N1 interface (abbreviated as N1); the RAN equipment communicates with an AMF network element through an N2 interface (N2 for short); the RAN equipment communicates with UPF network elements through an N3 interface (N3 for short); the SMF network element communicates with the UPF network element through an N4 interface (abbreviated as N4), and the UPF network element accesses a Data Network (DN) through an N6 interface (abbreviated as N6). In the architecture shown in fig. 3, N1, N2, N3, N4 and N6 represent reference points (reference points) between related network elements/network functions, respectively.

In addition, control plane functions such as an AUSF network element, an AMF network element, an SMF network element, an NSSF network element, a NEF network element, an NRF network element, a PCF network element, a UDM network element, a UDR network element, a CHF network element, or an AF network element shown in fig. 3 use a service interface to perform interaction. For example, the server interface provided by the AUSF network element is Nausf; the AMF network element provides a service interface as Namf; the SMF network element provides a serving interface as Nsmf; the NSSF network element provides a service interface for the outside as Nnssf; the network element of NEF provides a service interface for the outside as Nnef; the service interface externally provided by the NRF network element is Nnrf; the service interface externally provided by the PCF network element is an Npcf; the service interface externally provided by the UDM network element is Nudm; the server interface externally provided by the UDR network element is Nudr; the service interface externally provided by the CHF network element is Nchf; the service interface provided by the AF network element is Naf. The related functional descriptions and interface descriptions may refer to the 5G system architecture (5G system architecture) in the 23501 standard, and are not described herein.

It should be understood that the names of the above-mentioned core network devices, such as MME, SMF, AMF, etc., are only one name, and the device itself is not limited. It will be appreciated that other names may be used in 5G networks and other networks in the future, and embodiments of the present application are not specifically limited thereto. For example, the AMF network element may also be referred to as an AMF or an AMF entity, which in the embodiment of the present application is described only by taking the AMF network element as an example. Similarly, the SMF network element may also be referred to as an SMF or an SMF entity, and in this embodiment of the present application, the SMF network element is merely taken as an example for introduction.

Alternatively, the core network device may be implemented by one device, or may be implemented by a plurality of devices together, or may be a functional module in one device, which is not specifically limited in this embodiment of the present application. It will be appreciated that the functional modules described above may be either network elements in a hardware device, software functional modules running on dedicated hardware, or virtualized functional modules instantiated on a platform (e.g., a cloud platform).

In order to facilitate understanding of the embodiments of the present application, the following description will be given for the terms involved in the embodiments of the present application. It should be understood that these descriptions are merely for the purpose of facilitating understanding of the embodiments of the present application and should not be construed as limiting the application in any way.

1. Communication system

Communication formats, including but not limited to: second generation mobile communication technology (2 nd-generation wireless telephone technology, 2G) networks, third generation mobile communication technology (3 rd-generation wireless telephone technology, 3G) networks, fourth generation mobile communication technology (4 th-generation wirelesstelephone technology, 4G) networks, fifth generation mobile communication technology (5 th-generation wirelesstelephone technology, 5G) networks, and sixth generation mobile communication technology (6 th-generation wirelesstelephone technology, 6G) networks, and so forth. Among them, the 4G network may also be referred to as an evolved packet system (evolved packet system, EPS) network, and the 5G network may also be referred to as a New Radio (NR) network.

2、PLMN

A PLMN is a network established and operated by a government or its approved operators to provide land mobile services to the public. The PLMNs are interconnected with the public switched telephone network to form a communication network on a regional or national scale.

The PLMN consists of a mobile country number (mobile contrary code, MCC) and a mobile network number (MNC). MCC uniquely indicates the country to which the mobile subscriber belongs. For example, chinese MCC is 460. MNCs may uniquely represent networks in that country. For example, the MNC corresponding to chinese movement may include 00 and the MNC corresponding to chinese communication includes 01. Wherein different operators may correspond to different PLMNs. For example, a chinese mobile PLMN may include 46000, 46002, 46004, 46007, 46008; the PLMN of chinese communication may include 46001, 46006, 46009 and 46010. PLMNs of chinese telecommunications may include 46003, 46011 and 46012; the PLMN of china radio may include 46015. The PLMNs corresponding to the operators may further include other PLMNs, which are not limited in this embodiment of the present application.

3. Visiting network side (visited network operator), visiting network (visited network)

The visiting network side refers to an operator providing heterogeneous roaming service to terminal equipment of other operators in a roaming area. Wherein, a network providing heterogeneous roaming service to terminal equipment of other operators is described as a visited network. The foreign network roaming service may be a 5G core network foreign network roaming service.

4. Home network side (home network operator), home network (home network)

The home network side is an operator that provides a foreign network roaming service to a terminal device of the home network through other operator networks in the roaming area. Wherein, a network providing a foreign network roaming service to a terminal device of a home network through other operator networks is described as a home network. The foreign network roaming service may be a 5G core network foreign network roaming service.

Illustratively, the visited network may be a 5G network of the visited operator and the home network may be a 5G network of the home operator. As shown in fig. 4, in the 5G independent networking mode, the visited network and the home network are connected through a Border Gateway (BG). In some embodiments, the network element in the visited network and the network element in the home network are connected as shown in fig. 5. As shown in fig. 5, the SMF network element in the visited network is called a visited-SMF (V-SMF) network element. The SMF network element at the home network is called a home-SMF (H-SMF) network element. The PCF network element at the home network is called a home-PCF (H-PCF) network element.

5. Radio resource control (radio resource control, RRC)

In a 4G network, two RRC states are supported, namely an RRC IDLE state (rrc_idle), an RRC CONNECTED state (rrc_connected). In a 5G network, three RRC states are supported, namely, RRC IDLE state (rrc_idle), RRC INACTIVE state (rrc_inactive), RRC CONNECTED state (rrc_connected). Wherein the different RRC states can be switched.

At present, when a terminal device in an idle state moves from a 5G network to a 4G network, if at least one PDU session supporting interoperation exists in one PDU session established on the terminal device, the terminal device initiates a TAU request in the 4G network; if not, an initial attach request is initiated. Illustratively, if the PDU session of the terminal device holds the corresponding 4G parameter, it can be understood that the PDU session is a PDU session supporting interoperability. Conversely, if the PDU session of the terminal device does not store the corresponding 4G parameter, it can be understood that the PDU session is a PDU session that does not support interoperability. The 4G parameters corresponding to the PDU session include parameters of mapping the PDU session to the 4G network in the 5G network, such as EPS bearer identifier (EPS bearer identity, EBI), quality of service flow (quality of service, qoS flow) parameters corresponding to the 4G network, and the like. Under the condition that the terminal equipment initiates the TAU, a core network element MME of the 4G network acquires the context information of the terminal equipment from a core network element AMF of the 5G network, thereby completing the TAU.

However, in a roaming scenario, the terminal device still provides services using the SMF network element of the home network (i.e. the H-SMF network element). The SMF network element of the home network always sends the terminal device the 4G parameters corresponding to the PDU session. And when an interface is not opened between the AMF network element of the visiting network side and the MME network element of the home network side, if the terminal equipment moves from the 5G network of the visiting network to the 4G network of the home network, the MME cannot acquire the context information, so that TAU fails, the power consumption and the off-network time of the terminal equipment are increased, and the user experience is poor.

In view of this, the present embodiment provides three communication methods, and the communication method (such as the first communication method, the second communication method, or the third communication method) of the present embodiment may be applied to the communication system shown in fig. 1. In the embodiment of the present application, for a network element in a PLMN for providing services for a terminal device, for example, a mobility management entity may be described as a first mobility management entity, and a network element may be described as a first network element. For a network element in the home PLMN of the terminal equipment, the mobility management entity may be described as a second mobility management entity, and the network element may be described as a second network element. The names of messages between network elements or the names of parameters in the messages in the embodiments described below are only examples, and other names may be used in specific implementations. This is generally described herein, and will not be described in detail.

In the first communication method provided in the embodiment of the present application, the second network element determines that a PLMN for providing services for the terminal device belongs to the first PLMN. Wherein the number of the first PLMNs is at least one and is different from the home PLMNs of the terminal equipment. After that, the second network element does not send the target parameter to the terminal device, or the second network element sends the indication information to the terminal device. Wherein the indication information indicates the deletion target parameter. The target parameters comprise parameters of PDU session of a first communication system mapped to parameters of a second communication system, the communication system of PLMN providing service for the terminal equipment comprises the first communication system, the communication system of PLMN to which the terminal equipment belongs comprises the second communication system, and the first communication system is different from the second communication system. In this way, in the case that the PLMN serving the terminal device belongs to the first PLMN, the terminal device will not receive the target parameter, or delete the received target parameter. When the terminal equipment reselects from the PLMN of the first communication system which currently provides service for the terminal equipment to the PLMN of the second communication system which belongs to the terminal equipment, the terminal equipment does not initiate TAU any more because the terminal equipment does not store target parameters, so that the problem of TAU failure is avoided, the network disconnection time of the terminal equipment is shortened, and the power consumption of the terminal equipment is reduced.

As shown in fig. 6, a first communication method 600 provided in an embodiment of the present application includes the following steps:

s601, the second network unit determines that a PLMN providing service for the terminal device belongs to the first PLMN.

The second network element is a network element in the PLMN to which the terminal equipment belongs, and at least has a session management function. Illustratively, taking fig. 5 as an example, the second network element may be an H-SMF network element. It should be understood that, as the communication technology evolves, the second network element may also have other names, and the names of the network elements are not limited in the embodiments of the present application.

Wherein, the PLMN for providing service for the terminal equipment is different from the home PLMN of the terminal equipment. Illustratively, as shown in fig. 5, the PLMN serving the terminal device may be a visited PLMN to which the terminal device has access. The communication modes of the PLMN for providing service for the terminal equipment and the PLMN to which the terminal equipment belongs can be the same or different. In the embodiment of the present application, the description will be made only by taking, as an example, a PLMN that provides services for a terminal device and a PLMN to which the terminal device belongs have different communication schemes. Illustratively, the PLMN serving the terminal device may be a 5G network, and the terminal device home PLMN may be a 4G network, a 3G network, or a 2G network. Alternatively, the PLMN serving the terminal device may be a 4G network, and the terminal device home PLMN may be a 3G network, or a 2G network. Alternatively, the PLMN serving the terminal device may be a 3G network and the terminal device home PLMN may be a 2G network. In the embodiment of the present application, only the PLMN that provides services for the terminal device is a 5G network, and the terminal device home PLMN is a 4G network.

Wherein the number of the first PLMNs is at least one and is different from the home PLMNs of the terminal equipment. Illustratively, taking the example that the operator of the PLMN to which the terminal device belongs is a china mobile, the first PLMN may be a network of an operator other than the china mobile (e.g. china communication, china telecommunication, etc.). Taking the chinese UNICOM as an example, the first PLMN may comprise PLMNs identified by 46001, 46006. Alternatively, the first PLMN may be a PLMN in which one operator provides shared services to other operators. The first PLMN coverage area may be a remote area such as Xinjiang. Illustratively, taking the example of an operator china mobile providing shared services to china department, the access network device of the china mobile broadcasts two PLMN IDs, namely 460, 00 and 460, 30. Wherein 460, the PLMN identified by 00 provides service for terminal equipment of China mobile. 460 The PLMN identified by 30 is a PLMN shared by chinese mobile to provide services to terminal equipment of chinese mobile. The PLMN identified by 460, 30 above belongs to the first PLMN. For example, the first PLMN may be preconfigured for the second network element.

In some embodiments, the information of the first PLMN may be stored in the form of a table (list), or other form. In the case of a table stored, the table may be described as specifying a PLMN list, or other name, to which embodiments of the present application are not limited.

In the first communication method 600 of the present embodiment, the country to which the operator of the first PLMN and the PLMN to which the terminal device belongs belong may be the same or different, which is not limited herein.

Optionally, as shown in fig. 7, the second network element further executes S603, and accordingly, the implementation procedure of S601 includes S601a. The descriptions of S603 and S601a are as follows:

s603, the first mobility management entity sends the first information to the second network element. Accordingly, the second network element receives the first information from the first mobility management entity.

The first mobility management entity is a network element in a PLMN for providing services for the terminal device, and is mainly used for mobility management, access management, and the like. Illustratively, taking fig. 5 as an example, the first mobility management entity may be an AMF network element in the visited PLMN. It should be understood that, as the communication technology evolves, the first mobility management entity may also have other names, and the names of the entities are not limited in the embodiments of the present application.

The second network element may refer to the description of S601, which is not described herein.

The first information at least comprises information of an operator to which the first mobile management entity belongs. Illustratively, the first information includes a globally unique access and mobility management function identification (globally unique AMF identifier, guim). The GUAMI consists of MCC and MNC corresponding to AMF network element, 8bit AMF region identifier (AMF region ID), 10bit AMF set identifier (AMF set ID) and 6bit AMF pointer (AMF pointer). The MCC identifies the country to which the operator belongs, the MNC is the network identity of the operator, and the AMF region ID and AMF set ID are combined to represent a set of AMF network elements serving the same Tracking Area (TA) range, which are also referred to as AMF pool (AMF pool). The AMF region ID, AMF set ID, and AMF pointer are combined together to be referred to as AMF identification (AMFidentifier, AMI), unique under a set of MCCs and MNCs. The AMF region ID is unique under a set of MCCs and MNCs, and the AMF set ID is unique under the AMF region ID.

Illustratively, taking fig. 5 as an example, a first mobility management entity (i.e., an AMF network element) sends a GUAMI to a second network element (i.e., an H-SMF network element) through a V-SMF network element and BG. Accordingly, the second network element (i.e., the H-SMF network element) receives the GUAMI from the first mobility management entity (i.e., the AMF network element) via the V-SMF network element and the BG. The GUAMI may be transmitted through a PDU session creation context request message, or may be transmitted through a PDU session update request message, or may be transmitted through other messages, which is not limited in the embodiment of the present application. Next, a transmission procedure of the first information will be described with reference to fig. 8a and 8 b.

For example, during session establishment in a 5G network, a first mobility management entity (i.e., an AMF network element) sends a GUAMI to a second network element (i.e., an H-SMF network element) via a PDU session creation context request message. As shown in fig. 8a, the session establishment procedure comprises the steps of:

s11, the terminal equipment sends a PDU session establishment request (PDU session establishment request) message to the AMF network element. Correspondingly, the AMF network element receives a PDU session establishment request message from the terminal device.

Wherein the PDU session establishment request message requests establishment of a PDU session.

That is, the terminal device initiates a PDU session establishment request message to the AMF network element of the visited PLMN.

For the AMF network element, responding to the PDU session establishment request message, the AMF network element selects one SMF network element from at least one SMF network element in the visiting PLMN as a V-SMF network element, and selects one SMF network element from at least one SMF network element in the terminal equipment home PLMN as an H-SMF network element.

S12, the AMF network element sends a PDU session creation context request message to the V-SMF network element. Accordingly, the V-SMF network element receives the PDU session creation context request message from the AMF network element.

Illustratively, the PDU Session creation context request message in S12 may be denoted as a PDU Session creation context request (nsmf_pdu session_ CreateSMContext request) message transmitted by the Nsmf interface. The message includes a PDU session establishment request message and GUAMI. The GUAMI is the GUAMI of the AMF network element in S12.

S13, the V-SMF network element sends a PDU session creation context request message to the H-SMF network element. Accordingly, the H-SMF network element receives the PDU session creation context request message from the V-SMF network element.

The PDU session creation context request message in S13 may refer to the description of S12, and will not be described herein.

Thus, in the case that the H-SMF network element is used as the second network element and the GUAMI is used as the first information, the second network element may receive the first information through the session establishment procedure.

For another example, in the session modification procedure of the 5G network, the first mobility management entity (i.e., the AMF network element) sends the GUAMI to the second network element (i.e., the H-SMF network element) through a PDU session update context request message. In some embodiments, the terminal device may move from the 5G network of the home network side to the 5G network of the visited network side. In this case, the terminal device may initiate the session modification procedure. In addition, two mobile management entities involved in the session establishment process, namely, an AMF network element of a home PLMN accessed before the terminal equipment moves, are described as an old AMF (old AMF) network element, and an AMF network element of a visited PLMN accessed after the terminal equipment moves, are described as a new AMF (new AMF) network element. In this case, the first mobility management entity is a new AMF network element. As shown in fig. 8b, the session modification procedure comprises the steps of:

s21, the terminal equipment sends a registration request (registration request) message to the new AMF network element. Correspondingly, the new AMF network element receives the registration request message from the terminal device.

Illustratively, the registration request message includes registration type (registration type) information, the registration type (registration type) information indicating a mobile registration update (mobility registration updating).

S22, the new AMF network element sends a context request message to the old AMF network element. Accordingly, the old AMF network element receives the context request message from the new AMF.

Wherein the context request message is used for requesting context information of the terminal device. For example, the context request message may include a user equipment context transfer (namf_communication_uecontext transfer) request message transmitted by the Namf interface.

S23, the old AMF network element sends the context information to the new AMF network element. Accordingly, the new AMF network element receives the context information from the old AMF.

Wherein the context information in S23 includes context information of the terminal device. For example, the context information may be carried in a user equipment context transfer response (Namf Communication UEContextTransfer response) message transmitted by the Namf interface.

Exemplary context information of the terminal device includes, but is not limited to, the following: the identity of the PDU session, the internet protocol (internet protocol, IP) address used by the PDU session, the traffic and session continuity (service and session continuity, SSC) pattern of the PDU session, the context information of the QoS flow, etc. The PDU session is a session currently established by the terminal device, and the number of PDU sessions may be one or multiple.

S24, the new AMF network element sends PDU session update request information to the H-SMF network element. Accordingly, the H-SMF network element receives the PDU session update request message from the new AMF network element.

Wherein the PDU session update request message includes GUAMI. The GUAMI in S24 is the GUAMI of the new AMF network element.

Illustratively, the PDU Session update request message in S24 may be denoted as a PDU Session update context request (nsmf_pdu session_ UptateSMContext request) message transmitted by the Nsmf interface.

It should be noted that, in the embodiment of the present application, the AMF network element of the visited PLMN (i.e., the new AMF network element) sends the PDU session update request message to the SMF network element of the home PLMN (H-SMF network element), which means that, in the embodiment of the present application and in the drawing, the AMF network element of the visited PLMN (i.e., the new AMF network element) sends the PDU session update request message to the SMF network element of the visited PLMN (i.e., the V-SMF network element), and then the SMF network element of the visited PLMN (i.e., the V-SMF network element) sends the PDU session update request message to the H-SMF network element.

Thus, in the case that the H-SMF network element is used as the second network element and the GUAMI is used as the first information, the second network element may receive the first information through the session modification procedure.

After the second network element acquires the first information, S601a may be executed:

s601a, the second network unit determines that the PLMN providing the service for the terminal device belongs to the first PLMN according to the first information.

For example, taking the first information as a GUAMI, if the MNC and the MCC in the GUAMI are consistent with the MNC and the MCC in the first PLMN, the second network unit determines that the first mobility management entity belongs to the first PLMN, that is, the PLMN providing services for the terminal device belongs to the first PLMN.

Illustratively, in conjunction with the examples of fig. 8a and 8b, in fig. 8a, the GUAMI in the PDU session creation context request message is information of the AMF network element of the visited PLMN. In fig. 8b, taking the example that the terminal device moves from the 5G network of the home network side to the 5G network of the visiting network side, the GUAMI in the PDU session update request message is also the information of the AMF network element of the visiting network side. In this case, the second network element determines, based on information of an AMF network element of the PLMN visited by the terminal device, such as information of an operator to which the AMF network element belongs, that the PLMN serving the terminal device belongs to the first PLMN.

Optionally, as shown in fig. 7, the second network element further performs S604 before performing S601:

s604, the second network unit determines that the terminal equipment is in a roaming state.

The roaming state refers to an operator of a PLMN that serves the terminal device, which is different from an operator of a PLMN to which the terminal device belongs. For example, still taking the example that the operator of the PLMN to which the terminal device belongs is a china mobile, if the operator of the PLMN currently providing services for the terminal device is an operator other than the china mobile, such as one of china communication, china telecommunication and china radio and television, the terminal device is in a roaming state.

Roaming states include intra-country roaming and foreign roaming according to country division to which the operator belongs. The intra-country roaming means that the PLMN serving the terminal equipment is different from the home PLMN of the terminal equipment, but the PLMN serving the terminal equipment is the same as the country to which the home PLMN operator of the terminal equipment belongs. Foreign roaming means that the PLMN serving the terminal equipment is different from the home PLMN of the terminal equipment, and the PLMN serving the terminal equipment is different from the country to which the home PLMN operator of the terminal equipment belongs.

In S604, the terminal device may be in a state of roaming in a country or in a state of roaming abroad. In the first communication method 600 of the present embodiment, description will be made only taking an example that the terminal device is in a roaming state in a country.

Optionally, the implementation procedure of S604 is described as follows:

still taking fig. 5 as an example, the first network element is an SMF network element of the visited PLMN, i.e. a V-SMF network element, and the second network element is an SMF network element of the home PLMN, i.e. an H-SMF network element. If the terminal device is in roaming state, the message transmission procedure between the first network element (V-SMF network element) and the second network element (H-SMF network element) is as follows:

and a step a, the V-SMF network element sends a message to the BG. Accordingly, the BG receives messages from V-SMF network elements.

The message in step a may include the PDU session creation context request message, the PDU session update request message, or other messages, which is not limited in this embodiment of the present application. The message in step a carries at least information of the V-SMF network element, such as an identity of the V-SMF network element.

And b, sending a message to the H-SMF network element by the BG. Correspondingly, the H-SMF network element receives the message from the BG.

Wherein the message in step b is determined based on the message in step a. For example, the message in step b comprises the message in step a. The message in step b also includes BG information, such as BG identification.

For an H-SMF network element, in case the H-SMF network element is the second network element, S604 may be implemented as: if the second network element performs step b, it is determined that the terminal device is in a roaming state. Or the second network element (i.e. the H-SMF network element) determines that the terminal device is in the roaming state according to the identifier carried by the message in the step b (e.g. the identifier of the V-SMF network element or the identifier of the BG).

It will be appreciated that in case steps a and b are performed, it is also understood that the second network element receives a message from the first network element, in which case the second network element also determines that the terminal device is in a roaming state. Wherein the first network element has at least a session management function. In this embodiment, only fig. 5 is taken as an example, and the first network element may be a V-SMF network element. It should be understood that, as the communication technology evolves, the first network element may also have other names, and the names of the network elements are not limited in the embodiments of the present application.

Illustratively, in combination with the examples of fig. 8a and 8b, in the scenario shown in fig. 8a, the V-SMF network element sends a message to the H-SMF network element, steps a and b being performed. In the scenario shown in fig. 8b, in case the terminal device moves from the 5G network on the home network side to the 5G network on the visited network side, the V-SMF network element also sends a message to the H-SMF network element, steps a and b are performed. In both cases, the second network element (i.e. the H-SMF network element) determines that the terminal device is in a roaming state. Otherwise, if steps a and b are not performed, the second network element determines that the terminal device is not in the roaming state.

For the second network element, if the terminal device is in the roaming state, the second network element performs S601, otherwise, if the terminal device is not in the roaming state, the second network element does not need to perform S601, so as to simplify the processing procedure of the second network element. It should be understood that in fig. 7, the execution order of S604 and S601 is shown taking only the case where S601 is implemented as S601a as an example.

It should be noted that S603 and S604 are optional steps. In the case where both S603 and S604 are performed, if the message in step a (or step b) includes the PDU session creation context request message described above, or includes the PDU session update request message described above, the second network element may perform S603 first and then S604. If the message in the step a (or the step b) includes other messages, the second network element may execute S603 first, then execute S604, execute S604 first, then execute S603, and execute S603 and S604 simultaneously, which is not limited in the embodiment of the present application.

For the second network element, after S601 is performed, S602a may be performed as shown in the block of mode 1 in fig. 6, or S602b may be performed as shown in the block of mode 2 in fig. 6. The descriptions of S602a and S602b are as follows:

S602a, the second network element does not send the target parameter to the terminal device.

The target parameters include parameters of a PDU session of a first communication system mapped to parameters of a second communication system. The first communication system is different from the second communication system, for example, the first communication system may be 5G, the second communication system may be 4G, 3G, or 2G, or the first communication system may be 4G, and the second communication system may be 3G, or 2G. In the embodiment of the present application, only the first communication system is 5G, and the second communication system is 4G.

Exemplary, the target parameters are presented as follows: in a 5G network, a terminal device accesses a DN by creating a PDU session, which may contain one or more data flows, such as a quality of service flow (quality of service, qoS flow). In a 4G network, a terminal device accesses a DN by creating a packet data network connection (packet data network), which may contain multiple EPS bearers. As the location of the terminal device moves, the terminal device may move from the 5G network to the 4G network. Wherein, there is a corresponding matching relationship between QoS flow in the 5G network and EPS bearing in the 4G network. For quality of service flows (QoS flows) that may switch to the 4G network, the second network element will allocate a corresponding EPS bearer identity (EPS bearer identity, EBI). In this case, the target parameters may include 4G parameters of the PDU session, such as parameters of QoS flows, EBI, etc.

Optionally, the second network element does not allocate the target parameter to the terminal device. In this case the second network element does not send the target parameters to the terminal device either. Illustratively, the following details are described in connection with a session establishment procedure of a 5G network:

as shown in fig. 8a, the session establishment procedure comprises the steps of:

s14, when the H-SMF network element does not distribute target parameters for the terminal equipment, the H-SMF network element sends PDU session creation context response information to the V-SMF network element. Accordingly, the V-SMF network element receives the PDU session creation context response message from the H-SMF network element.

Illustratively, the PDU Session creation context response message in S14 may be denoted as a PDU Session creation context response (nsmf_pdu session_ CreateSMContext response) message transmitted by the Nsmf interface. The message includes a PDU session establishment accept (PDU session establishment accept) message. The PDU session establishment accept message does not carry the above-mentioned target parameters.

S15, the V-SMF network element sends a PDU session creation context response message to the AMF network element. Accordingly, the AMF network element receives the PDU session creation context response message from the V-SMF network element.

The PDU session creation context response message in S15 may refer to the description of S14, and will not be described herein.

S16, the AMF network element sends PDU session establishment acceptance information to the terminal equipment. Correspondingly, the terminal equipment receives the PDU session establishment acceptance message from the AMF network element.

The PDU session establishment acceptance message in S16 may be referred to in S14, and will not be described herein.

In this way, in the case that the H-SMF network element is used as the second network element and the target parameter is not allocated to the terminal device, the second network element sends a PDU session establishment acceptance message that does not carry the target parameter. In this way, the second network element does not send the target parameter to the terminal device, and it may be specifically implemented that the PDU session establishment acceptance message does not carry the target parameter, and accordingly, the terminal device cannot receive the target parameter from the second network element.

S602b, the second network unit sends indication information to the terminal equipment. Correspondingly, the terminal device receives the indication information from the second network element.

Wherein the indication information indicates the deletion target parameter. The target parameters in S602b are consistent with the target parameters in S602a, and will not be described herein.

Exemplary, in connection with the session modification procedure of the 5G network, the transmission procedure of the indication information will be described in detail:

As shown in fig. 8b, the description is still given taking as an example that the terminal device can move from the 5G network of the home network side to the 5G network of the visited network side. The session modification procedure comprises the following steps:

s25, the H-SMF network element sends PDU session update response information to the new AMF network element. Correspondingly, the new AMF network element receives the PDU session update response message from the H-SMF network element.

The PDU session update response message comprises a PDU session modification command message, wherein the PDU session modification command message carries indication information to indicate the terminal equipment to delete the target parameter.

Illustratively, the PDU Session update response message may be transmitted over an Nspf interface, denoted as an NspSession UptateSMContext response message. The PDU session modification command message may be noted as PDU Session Modification Command message. PDU Session Modification Command message includes a mapped EPS bearer context (Mapped EPS bearer contexts). Wherein the mapped EPS bearing context is indicated by the deletion of the new EPS bearing (delete new EPS bearer) carried in an operation code (operation code). The indication information may be implemented as the deletion of the new EPS bearer indication.

S26, the new AMF network element sends a registration acceptance (registration accept) message to the terminal equipment. Accordingly, the terminal device receives a registration accept message from the new AMF network element.

S27, the new AMF network element sends PDU session modification command information to the terminal equipment. Correspondingly, the terminal device receives the PDU session modification command message from the new AMF network element.

Wherein the PDU session modification command message in S27 carries the mapped EPS bearer context to transmit the indication information to the terminal device.

S28, the terminal equipment sends PDU session modification command confirmation information to the new AMF network element. Correspondingly, the new AMF network element receives the PDU session modification command acknowledgement message from the terminal device.

Illustratively, the PDU session modification command acknowledgement message may be noted as PDU Session Modification Command ACK. Correspondingly, the terminal device deletes the 4G parameters corresponding to the PDU session, such as the EBI and 4G QoS parameters.

In this way, in the case that the H-SMF network element is used as the second network element and the indication information is sent to the terminal device, the second network element sends the indication information to the terminal device by sending the PDU session modification command message, so as to instruct the terminal device to delete the target parameter.

In the above description, only the PLMN serving the terminal device is described as belonging to the first PLMN. Of course, the PLMN serving the terminal equipment may not belong to the first PLMN. In this case, the second network element sends the target parameters to the terminal device, see for details the processing steps shown in fig. 9:

S901, the second network unit determines that the PLMN for providing services for the terminal device does not belong to the first PLMN.

The second network element and the first PLMN may refer to the description of S601, which is not repeated herein.

The description of the PLMN for providing services to the terminal device is as follows:

as a possible implementation, the PLMN serving the terminal device is the same as the home PLMN of the terminal device. That is, the PLMN currently accessed by the terminal device is the home PLMN of the terminal device. In this case, the terminal device is not in a roaming state, and the country to which the first PLMN and the home PLMN operator of the terminal device belong may be the same or different, which is not limited herein. For example, taking an example that the home PLMN of the terminal device is a china mobile operator network, the first PLMN may include PLMNs of home operators and may also include PLMNs of other home operators.

As another possible implementation, the PLMN serving the terminal device is different from the country to which the terminal device belongs to the PLMN operator. That is, the PLMN currently accessed by the terminal device is a foreign operator network. In this case, the terminal device is in a foreign roaming state. In this implementation, the first PLMN is the same country to which the terminal device home PLMN operator belongs. Still, for example, the terminal device home PLMN is a china mobile operator network, and the first PLMN only includes PLMNs of domestic operators, and does not include PLMNs of other national operators.

Optionally, as shown in fig. 10a, the second network element further executes S903, and accordingly, the implementation procedure of S901 includes S901a. The descriptions of S903 and S901a are as follows:

s903, the first mobility management entity sends the first information to the second network element. Accordingly, the second network element receives the first information from the first mobility management entity.

The second network element and the first information may refer to the description of S603, which is not repeated herein.

The first mobility management entity is a network element in a PLMN currently providing service for the terminal device, and is mainly used for mobility management, access management and the like. Taking a 5G network as an example, the first mobility management entity may be an AMF network element. It should be understood that, as the communication technology evolves, the first mobility management entity may also have other names, and the names of the entities are not limited in the embodiments of the present application. Illustratively, when the PLMN serving the terminal device is the same as the terminal device home PLMN, the first mobility management entity is a network element in the terminal device home PLMN. When the PLMN serving the terminal equipment is different from the country to which the PLMN operator to which the terminal equipment belongs, the first mobility management entity is a network element in the PLMN of the other country operator.

Taking an example that the first mobility management entity is a network element in the PLMN to which the terminal device belongs as an example, the transmission process of the first information is described: the terminal device moves from the 5G network of the visited network side to the 5G network of the home network side. In this case, the terminal device may initiate the session modification procedure. And, there are two mobility management entities involved in the session establishment procedure, a new AMF network element and an old AMF network element. In this scenario, the first mobility management entity is a network element of the PLMN to which the terminal device belongs, and still belongs to a new AMF network element, and the specific process may still be described with reference to fig. 8b, which is not described herein again.

After the second network element obtains the first information, S901a may be executed:

and S901a, the second network unit determines that the PLMN providing the service for the terminal equipment does not belong to the first PLMN according to the first information.

For example, taking the first information as a GUAMI, if the MNC and the MCC in the GUAMI are inconsistent with the MNC and the MCC in the first PLMN, the second network unit determines that the first mobility management entity does not belong to the first PLMN, i.e. the PLMN providing services for the terminal device does not belong to the first PLMN.

Illustratively, as a possible scenario, taking the example of the terminal device moving from the 5G network of the visited network side to the 5G network of the home network side, in connection with fig. 8b, the guami is also information of an AMF network element of the home network side. In this case, the second network element determines, based on the information of the AMF network element of the home network side, that the PLMN serving the terminal device does not belong to the first PLMN.

As another possible scenario, the PLMN serving the terminal device is different from the country to which the operator of the PLMN to which the terminal device belongs. I.e. the terminal device is in roaming state and belongs to foreign roaming state. Since the first PLMN is the same country as the home PLMN operator of the terminal equipment. In this case, the PLMN serving the terminal equipment is also not belonging to the first PLMN.

In this way, the second network element may determine, based on the information of the operator to which the first mobility management entity belongs, that the PLMN serving the terminal device does not belong to the first PLMN.

Optionally, as shown in fig. 10b, for a case that the PLMN for providing services to the terminal equipment is different from the country to which the operator of the PLMN to which the terminal equipment belongs, i.e. the terminal equipment is in a state of roaming abroad, the second network element may further perform S904:

s904, the second network element determines that the terminal device is in a roaming state.

The roaming state may be referred to as S604, and will not be described herein.

For example, the implementation process of S904 may refer to the description of S604, such as step a and step b in S604, which are not described herein. Taking still the example that the PLMN serving the terminal equipment is a PLMN of another national operator, steps a and b are performed, and the second network element may determine that the terminal equipment is in a roaming state.

For the second network element, if the terminal device is in the roaming state, the second network element performs S901, so as to determine whether the PLMN for providing services for the terminal device belongs to the first PLMN, so as to simplify the processing procedure of the second network element. It will be appreciated that in this case the first PLMN is the same country as the country to which the terminal device belongs to the PLMN operator.

It should be noted that S903 and S904 are optional steps. In the case where both S903 and S904 are performed, if the message in step a (or step b) includes the above PDU session creation context request message or includes the above PDU session update request message, the second network element may perform S903 first and then S904. If the message in the step a (or the step b) includes other messages, the second network element may execute S903 first, then execute S904, execute S904 first, then execute S903, and execute S903 and S904 simultaneously.

S902, the second network unit sends target parameters to the terminal equipment. Correspondingly, the terminal device receives the target parameters from the second network element.

The target parameters may be described in S602a, which is not described herein.

Illustratively, the transmission procedure of the target parameter is described in detail in connection with the session modification procedure:

as shown in fig. 8b, the description is still given taking as an example that the terminal device can move from the 5G network of the visited network side to the 5G network of the home network side. In this case, the PDU session modification command message includes the following parameters: a PDU Session identification (PDU Session ID), qoS parameters corresponding to QoS flows (QoS Flow level QoS parameters), mapped EPS bearer context (Mapped EPS bearer contexts). The PDU session identifier is used for identifying a PDU session, the QoS parameters corresponding to the QoS flows carry EBI corresponding to the QoS flows, the mapped EPS bearing context carries 1 or more 4G QoS parameters and EBI corresponding to the QoS flows, and the mapped EPS bearing context carries an instruction of creating a new EPS bearing (Create new EPS bearer) through an operation code (operation code). Wherein, the EBI and 4G QoS parameters belong to target parameters. That is, in contrast to the PDU session modification command message in S602b, the PDU session modification command message no longer carries indication information, but carries target parameters.

In this way, in case of the H-SMF network element as the second network element, the second network element transmits the target parameter to the terminal device by transmitting the PDU session modification command message to provide the target parameter to the terminal device.

In the second communication method provided in the embodiment of the present application, when the terminal device reselects from the first communication system of the first PLMN to the second communication system of the PLMN to which the terminal device belongs, a registration request message is sent to the second mobility management entity of the PLMN to which the terminal device belongs. The method comprises the steps that a first PLMN is different from a PLMN to which a terminal device belongs, a first communication system is different from a second communication system, target parameters are stored in the terminal device, and the target parameters comprise parameters of a protocol data unit PDU session of the first communication system mapped to parameters of the second communication system. The terminal device then receives a registration accept message from the second mobility management entity. In this way, even if the first PLMN is different from the PLMN to which the terminal device belongs, and the terminal device stores the target parameters, when the terminal device moves from the first communication system of the first PLMN to the second communication system of the PLMN to which the terminal device belongs, the terminal device initiates the registration request message, and no TAU is initiated, thereby avoiding the problem of TAU failure, being beneficial to shortening the off-network time of the terminal device and reducing the power consumption of the terminal device.

As shown in fig. 11, a second communication method 1100 provided in the embodiment of the present application includes the following steps:

S1101, the terminal equipment determines to reselect or switch from the first communication mode of the first PLMN to the second communication mode of the PLMN to which the terminal equipment belongs.

The first communication system and the second communication system may be described in S602a, which is not described herein. Exemplary, the scene shown in S1101 includes: the terminal device moves from the 5G network of the visited PLMN to the 4G network of the home PLMN of the terminal device. In this case, the processing procedure performed by the terminal device includes S1101 described above. For example, if the terminal device moves in the idle state, the terminal device reselects from the first communication system of the first PLMN to the second communication system of the PLMN to which the terminal device belongs. If the terminal equipment moves in the connected state, the terminal equipment is switched from a first communication mode of the first PLMN to a second communication mode of the PLMN to which the terminal equipment belongs.

In this embodiment, taking fig. 5 as an example, the first PLMN may be a visited PLMN of the terminal device, and the description of S601 may be specifically referred to herein and will not be repeated.

The terminal device stores the target parameters, which can be described in S602a and will not be described herein. The target parameter stored by the terminal device may be generated by the terminal device itself or may be received from the second network element, which is described in detail in S902 and will not be described herein.

S1102, the terminal equipment sends a registration request message to a second mobile management entity. Accordingly, the second mobility management entity receives the registration request message from the terminal device.

The second mobility management entity is a network element in the PLMN to which the terminal equipment belongs, and is mainly used for mobility management, access management and the like. Illustratively, taking a 4G network as an example, the second mobility management entity may be an MME. It should be understood that, as the communication technology evolves, the first mobility management entity may also have other names, and the names of the entities are not limited in the embodiments of the present application. The registration request message may be denoted as an initial attach message. That is, the terminal device sends an initial attach message to the MME. Correspondingly, the MME receives an initial attach message from the terminal device.

S1103, the second mobility management entity sends a registration accept message to the terminal device. Correspondingly, the terminal device receives a registration accept message from the second mobility management entity.

Illustratively, still taking a 4G network as an example, the second mobility management entity may be an MME. The registration accept message may be denoted as an attach accept message. That is, the MME sends an attach accept message to the terminal device. Correspondingly, the terminal device receives the attach accept message from the MME.

In some embodiments, as shown in fig. 12, the terminal device further performs S1104 before S1102:

s1104, the terminal equipment determines that the first PLMN is different from the home PLMN of the terminal equipment according to the first information.

The first information includes information of at least one third PLMN, which is different from the home PLMN of the terminal equipment, and the third PLMN includes the first PLMN. Illustratively, taking the example that the operator of the PLMN to which the terminal device belongs is a china mobile, the third PLMN may be a network of an operator other than the china mobile (e.g. china communication, china telecommunication, etc.). Taking the chinese UNICOM as an example, the third PLMN may comprise PLMNs identified by 46001, 46006. Alternatively, the third PLMN may be a PLMN in which one operator provides shared services to other operators. The third PLMN coverage area may be a remote area such as Xinjiang. Illustratively, taking the example of an operator china mobile providing shared services to china department, the access network device of the china mobile broadcasts two PLMN IDs, namely 460, 00 and 460, 30. Wherein 460, the PLMN identified by 00 provides service for terminal equipment of China mobile. 460 The PLMN identified by 30 is a PLMN shared by chinese mobile to provide services to terminal equipment of chinese mobile. The PLMN identified by 460, 30 above belongs to a third PLMN. Illustratively, the third PLMN may be preconfigured. The first information comprises information of at least one third PLMN that is preconfigured.

In the second communication method 1100 according to the embodiment of the present application, the country to which the operator of the third PLMN and the PLMN to which the terminal device belongs may be the same or different, which is not limited herein.

It should be understood that S1104 is an optional step, and in the case where S1104 is performed, the terminal device may perform S1104 first, then S1101, may perform S1101 first, then S1104, and may perform S1101 and S1104 simultaneously, which is not limited in this embodiment of the present application.

The manner in which the terminal device obtains the first information includes the following two ways:

optionally, as shown in the block of "mode 1" in fig. 12, the terminal device further executes S1105a:

s1105a, the second mobility management entity sends the first information to the terminal device. Correspondingly, the terminal device receives the first information from the second mobility management entity.

The first information in S1105a is consistent with the first information in S1104, and will not be described herein.

The terminal device may, for example, obtain the first information during a registration procedure of the home network. Specifically, the terminal device sends a registration request message to the second mobility management entity. Accordingly, the second mobility management entity receives the registration request message from the terminal device. The second mobility management entity then sends a registration accept message to the terminal device. Correspondingly, the terminal device receives a registration accept message from the second mobility management entity. Wherein the registration accept message comprises the first information and equivalent public land mobile network (equivalent public land mobile network, EPLMN) information. In this case, the EPLMN information includes information of the first PLMN described above so that the terminal equipment resides in the first PLMN.

Therefore, the terminal equipment can acquire the first information in the registration process of the home network, so that when the terminal equipment reselects from the first communication system of the first PLMN to the second communication system of the home PLMN of the terminal equipment, the registration request message can be initiated in time, and the problem of TAU failure is effectively avoided.

Optionally, as shown in the block of "mode 2" in fig. 12, the terminal device further executes S1105b:

s1105b, the second network unit sends the first information to the terminal device. Correspondingly, the terminal device receives the first information from the second network element.

The first information in S1105b is consistent with the first information in S1104, and will not be described herein.

Illustratively, during the PDU session establishment procedure, the second network element sends the first information to the terminal device via a PDU session establishment accept message. Accordingly, the terminal device receives the first information from the second network element via a PDU session establishment acceptance message. In the implementation process of S1105b, the PDU session establishment acceptance messages of S14, S15 and S16 all carry the first information, as shown in fig. 8 a.

Therefore, the terminal equipment can acquire the first information in the PDU session establishment process, so that when the terminal equipment reselects from the first communication system of the first PLMN to the second communication system of the PLMN to which the terminal equipment belongs, the registration request message can be initiated in time, and the problem of TAU failure is effectively avoided.

In the third communication method provided in the embodiment of the present application, the terminal device sends a registration request message to the first mobility management entity of the first PLMN. Wherein the first PLMN is different from the home PLMN of the terminal equipment. The terminal device receives a registration accept message from the first mobility management entity. And then the terminal device deletes the target parameter, or the terminal device does not generate the target parameter, or when the terminal device receives the target parameter from the second network unit, the terminal device does not store the target parameter. The target parameters include parameters of a protocol data unit PDU session of a first communication system mapped to parameters of a second communication system, the communication system of the first PLMN includes the first communication system, and the communication system of the PLMN to which the terminal device belongs includes the second communication system. That is, even if the first PLMN is different from the home PLMN of the terminal device, and the terminal device has deleted the target parameter after the first PLMN registration, or does not generate the target parameter, or does not save the target parameter when the terminal device receives the target parameter from the second network element. In this way, when the terminal equipment reselects from the first communication system of the first PLMN to the second communication system of the PLMN to which the terminal equipment belongs, the terminal equipment initiates the registration request message and does not initiate the TAU any more because the terminal equipment does not save the target parameters, thereby avoiding the problem of TAU failure, being beneficial to shortening the network disconnection time of the terminal equipment and reducing the power consumption of the terminal equipment.

As shown in fig. 13, a third communication method 1300 provided in an embodiment of the present application includes the following steps:

s1301, the terminal equipment sends a registration request message to a first mobility management entity of a first PLMN. Correspondingly, the first management network element receives a registration request message from the terminal device.

The first PLMN is different from the home PLMN of the terminal device, and may be referred to the description of S1101, which is not repeated herein.

The first mobility management entity is a network element in a PLMN for providing services for the terminal device, and is mainly used for mobility management, access management, and the like. Illustratively, taking fig. 5 as an example, the first PLMN is a terminal equipment visited network, and the first mobility management entity is an AMF network element in the terminal equipment visited network. It should be understood that, as the communication technology evolves, the first mobility management entity may also have other names, and the names of the entities are not limited in the embodiments of the present application. The terminal device sends a registration request message to the AMF network element. Accordingly, the AMF network element receives the registration request message from the terminal device.

S1302, the first mobility management entity sends a registration acceptance message to the terminal device. Accordingly, the terminal device receives a registration accept message from the first mobility management entity.

Illustratively, still taking fig. 5 as an example, the first PLMN is a terminal equipment visited network and the first mobility management entity is an AMF network element in the terminal equipment visited network. The AMF network element sends a registration acceptance message to the terminal device. Correspondingly, the terminal device receives a registration acceptance message from the AMF network element. Thus, the terminal device can complete the registration process in the first PLMN, and is in the registration state in the first PLMN.

After the terminal device performs S1302, S1303a may be performed as shown in the block of "mode 1" in fig. 13, S1303b may be performed as shown in the block of "mode 2" in fig. 13, and S1303c may be performed as shown in the block of "mode 3" in fig. 13. The descriptions of S1303a, S1303b, and S1303c are as follows:

s1303a, the terminal device deletes the target parameters.

The target parameters may be described in S602a, which is not described herein.

For example, the target parameter deleted by the terminal device may be a parameter received from the second network element, which may be described in S902 and will not be described herein.

S1303b, the terminal device does not generate the target parameter.

The target parameters may be described in S602a, which is not described herein.

That is, the terminal device does not generate the target parameter after the registration of the first PLMN. Or when the terminal equipment reselects from the first communication system of the first PLMN to the second communication system of the PLMN to which the terminal equipment belongs, the terminal equipment does not generate the target parameters.

S1303c, when the terminal device receives the target parameter from the second network element, the target parameter is not saved.

The second network element may refer to the description of S601, and the target parameter may refer to the description of S602a, which is not described herein.

Illustratively, taking the PDU session modification procedure as an example, the second network element sends the PDU session modification command message to the terminal device, see the description of S25 and S27 in fig. 8b for details, which are not repeated here. The PDU session modification command message carries the target parameter. In this case, even if the terminal device receives the target parameter from the second network element, the target parameter is not saved.

In some embodiments, the terminal device further performs S1104, that is, the terminal device determines that the first PLMN and the home PLMN of the terminal device are different according to the first information, before S1303a (or S1303b, or S1303 c). The manner in which the terminal device obtains the first information may refer to the description of S1105a and S1105b, which are not described herein.

The above description has been presented mainly from the point of interaction between the network elements. Correspondingly, the embodiment of the application also provides a communication device, which can be the network element in the embodiment of the method, or a device containing the network element, or a component applicable to the network element. It will be appreciated that the communication device, in order to achieve the above-described functions, comprises corresponding hardware structures and/or software modules performing the respective functions. Those of skill in the art will readily appreciate that the elements and algorithm steps of the examples described in connection with the embodiments disclosed herein may be implemented as hardware or combinations of hardware and computer software. Whether a function is implemented as hardware or computer software driven hardware depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

Illustratively, fig. 14 shows a schematic structural diagram of a communication device 1400. The communication apparatus 1400 includes a processing unit 1401, a transmitting unit 1402, and a receiving unit 1403.

In a possible example, taking the communication apparatus 1400 as an example of a terminal device, the processing unit 1401 is configured to support the terminal device to perform other processing operations that the terminal device in fig. 6 needs to perform. The sending unit 1402 is configured to support the terminal device to perform other sending operations that the terminal device needs to perform in fig. 6. The receiving unit 1403 is configured to support the terminal device to perform S602b in fig. 6, and/or other receiving operations that the terminal device needs to perform in the embodiment of the present application.

In another possible example, taking the communication apparatus 1400 as a terminal device, the processing unit 1401 is configured to support the terminal device to perform S1101 in fig. 11, and/or other processing operations that the terminal device needs to perform in the embodiment of the present application. The sending unit 1402 is configured to support the terminal device to perform S1102 in fig. 11, and/or other sending operations that the terminal device needs to perform in the embodiment of the present application. The receiving unit 1403 is configured to support the terminal device to perform S1103 in fig. 11, and/or other receiving operations that the terminal device needs to perform in the embodiment of the present application.

In another possible example, taking the communication apparatus 1400 as a terminal device, the processing unit 1401 is configured to support the terminal device to perform S1303a, S1303b, or S1303c in fig. 13, and/or other processing operations that the terminal device needs to perform in the embodiment of the present application. The sending unit 1402 is configured to support the terminal device to perform S1301 in fig. 13, and/or other sending operations that the terminal device needs to perform in the embodiment of the present application. The receiving unit 1403 is configured to support the terminal device to perform S1302 in fig. 13, and/or other receiving operations that the terminal device needs to perform in the embodiment of the present application.

In a possible example, taking the communication apparatus 1400 as the second network element, the processing unit 1401 is configured to support the second network element to perform S601 in fig. 6, and/or other processing operations that the second network element needs to perform in the embodiment of the present application. The sending unit 1402 is configured to support the second network unit to perform S602b in fig. 6, and/or other sending operations that the second network unit needs to perform in the embodiments of the present application. The receiving unit 1403 is configured to support the second network element to perform other receiving operations that the second network element needs to perform in fig. 6.

In yet another possible example, taking the communication apparatus 1400 as the second mobility management entity as an example, the processing unit 1401 is configured to support the second mobility management entity to perform other processing operations that the second mobility management entity needs to perform in fig. 11. The sending unit 1402 is configured to support the second mobility management entity to perform S1103 in fig. 11, and/or other sending operations that the second mobility management entity needs to perform in the embodiment of the present application. The receiving unit 1403 is configured to support the second mobility management entity to perform S1102 in fig. 11, and/or other receiving operations that the second mobility management entity needs to perform in the embodiment of the present application.

In yet another possible example, taking the communication apparatus 1400 as the first mobility management entity as an example, the processing unit 1401 is configured to support the first mobility management entity to perform other processing operations that the first mobility management entity needs to perform in fig. 13. The sending unit 1402 is configured to support the first mobility management entity to perform S1302 in fig. 13, and/or other sending operations that the first mobility management entity needs to perform in the embodiments of the present application. The receiving unit 1403 is configured to support the first mobility management entity to perform S1301 in fig. 13, and/or other receiving operations that the first mobility management entity needs to perform in the embodiment of the present application.

Optionally, the communication device 1400 may further include a storage unit 1404 for storing program code and data of the communication device, which may include, but is not limited to, raw data or intermediate data, etc.

The processing unit 1401 may be a processor or controller, such as a CPU, general purpose processor, application specific integrated circuit (application specific integrated circuit, ASIC), field programmable gate array (field programmable gate array, FPGA) or other programmable logic device, transistor logic device, hardware components, or any combination thereof. Which may implement or perform the various exemplary logic blocks, modules, and circuits described in connection with this disclosure. A processor may also be a combination that performs computing functions, e.g., including one or more microprocessors, a combination of a DSP and a microprocessor, and so forth.

The transmitting unit 1402 may be a communication interface, a transmitter, or a transmitting circuit, where the communication interface is generally called, and in a specific implementation, the communication interface may include a plurality of interfaces, for example, may include: an interface between the terminal device and the second network element and/or other interfaces.

The receiving unit 1403 may be a communication interface, a receiver, or a receiving circuit, where the communication interface is generally called, and in a specific implementation, the communication interface may include multiple interfaces, for example may include: an interface between the terminal device and the second network element and/or other interfaces.

The transmitting unit 1402 and the receiving unit 1403 may be physically or logically implemented as one and the same unit.

The storage unit 1404 may be a memory.

When the processing unit 1401 is a processor, the transmitting unit 1402 and the receiving unit 1403 are communication interfaces, and the storage unit 1404 is a memory, the communication apparatus according to the embodiment of the present application may be as shown in fig. 15.

Referring to fig. 15, the communication device includes: a processor 1501, a communication interface 1502, and a memory 1503. Optionally, the communication device may also include a bus 1504. Wherein the communication interface 1502, the processor 1501 and the memory 1503 may be interconnected by a bus 1504; bus 1504 may be a peripheral component interconnect standard (peripheral component interconnect, PCI) bus or an extended industry standard architecture (extended industry standard architecture, EISA) bus, or the like. The bus 1504 may be divided into an address bus, a data bus, a control bus, and the like. For ease of illustration, only one thick line is shown in fig. 15, but not only one bus or one type of bus.

Optionally, the embodiments of the present application further provide a computer program product carrying computer instructions that, when run on a computer, cause the computer to perform the method described in the above embodiments.

Optionally, the embodiment of the present application further provides a computer readable storage medium, where the computer readable storage medium stores computer instructions, which when executed on a computer, cause the computer to perform the method described in the above embodiment.

Optionally, an embodiment of the present application further provides a chip, including: processing circuitry and transceiver circuitry for implementing the methods described in the above embodiments. Wherein the processing circuit is used for executing the processing actions in the corresponding method, and the transceiver circuit is used for executing the receiving/transmitting actions in the corresponding method.

In the above embodiments, it may be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When loaded and executed on a computer, produces a flow or function in accordance with embodiments of the present application, in whole or in part. The computer may be a general purpose computer, a special purpose computer, a computer network, or other programmable apparatus. The computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center by a wired (e.g., coaxial cable, fiber optic, digital subscriber line (digital subscriber line, DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer readable storage medium may be any available medium that can be accessed by a computer or a data storage device including one or more servers, data centers, etc. that can be integrated with the available medium. The usable medium may be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., digital video disc (digital video disc, DVD)), or a semiconductor medium (e.g., solid state disk (solid state drive, SSD)), etc.

In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods may be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative, and for example, the division of the modules is merely a logical function division, and there may be additional divisions when actually implemented, for example, multiple modules or components may be combined or integrated into another system, or some features may be omitted or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices or modules, which may be in electrical or other forms.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of devices. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

From the above description of the embodiments, it will be clear to those skilled in the art that the present application may be implemented by means of software plus necessary general purpose hardware, or of course by means of hardware, but in many cases the former is a preferred embodiment. Based on such understanding, the technical solution of the present application may be embodied essentially or in contributing parts in the form of a software product stored in a readable storage medium, such as a floppy disk, a hard disk, or an optical disk of a computer, etc., including several instructions to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to perform the methods described in the embodiments of the present application.

The foregoing is merely a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and the changes or substitutions within the technical scope of the present disclosure should be covered in the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A method of communication, comprising:

a second network element determines that a third public land mobile network PLMN for providing service for terminal equipment belongs to a first PLMN, wherein the second network element is a network element in the PLMN to which the terminal equipment belongs, and the number of the first PLMNs is at least one and is different from that of the PLMNs to which the terminal equipment belongs;

the second network unit does not send the first target parameter to the terminal equipment, or the second network unit sends indication information to the terminal equipment, wherein the indication information indicates that the first target parameter is deleted; the first target parameters include parameters of a protocol data unit PDU session of a first communication system mapped to parameters of a second communication system, a communication system of a third PLMN providing service for the terminal device includes the first communication system, a communication system of a PLMN to which the terminal device belongs includes the second communication system, and the first communication system is different from the second communication system.

2. The method of claim 1, wherein the step of determining the position of the substrate comprises,

the method further comprises the steps of:

the second network element receives first information from a third mobility management entity, wherein the third mobility management entity is a network element in a third PLMN for providing services for the terminal device, and the first information includes information of an operator to which the third mobility management entity belongs;

the second network element determining that a third PLMN for providing services for the terminal equipment belongs to the first PLMN, including:

and the second network unit determines that a third PLMN for providing service for the terminal equipment belongs to the first PLMN according to the first information.

3. The method according to claim 1 or 2, wherein the second network element determines that a third PLMN serving the terminal device belongs to the first PLMN, comprising:

and when the second network unit determines that the terminal equipment is in a roaming state, the second network unit determines that a third PLMN for providing services for the terminal equipment belongs to the first PLMN.

4. A method according to claim 3, characterized in that the method further comprises:

the second network element receives second information from a third network element or a third border gateway BG, where the third network element is a network element in a third PLMN that provides services for the terminal device, and the third BG is configured to connect the second network element and the third network element;

And the second network unit determines that the terminal equipment is in a roaming state according to the second information.

5. The method according to any one of claim 1 to 4, wherein,

the method further comprises the steps of:

the second network unit sends PDU session establishment acceptance message to the terminal equipment;

the second network element not sending the first target parameter to the terminal device, including:

the PDU session establishment acceptance message does not carry the first target parameter.

6. The method according to any of claims 1 to 4, wherein the second network element sends the indication information to the terminal device by means of a PDU session modification command message.

7. The method according to any of claims 1 to 6, wherein the first PLMN is preconfigured.

8. The method according to any one of claims 1 to 7, further comprising:

the second network element determines that a fourth PLMN serving the terminal equipment does not belong to the first PLMN;

and the second network unit sends a second target parameter to the terminal equipment, wherein the second target parameter comprises a parameter of a PDU (protocol data unit) session of a first communication system mapped to a parameter of a second communication system, and a communication system of a fourth PLMN for providing service for the terminal equipment comprises the first communication system.

9. The method of claim 8, wherein the fourth PLMN that serves the terminal device is the terminal device home PLMN.

10. The method of claim 8, wherein the fourth PLMN serving the terminal device is different from a country to which an operator of the PLMN to which the terminal device belongs.

11. The method of claim 10, wherein the second network element determining that a fourth PLMN serving the terminal device is not of the first PLMN comprises:

and when the second network unit determines that the terminal equipment is in the roaming state, the second network unit determines that a fourth PLMN for providing services for the terminal equipment does not belong to the first PLMN.

12. The method of claim 11, wherein the method further comprises:

the second network element receives fourth information from a fourth network element or a fourth border gateway BG, where the fourth network element is a network element in a fourth PLMN that provides services for the terminal device, and the fourth BG is configured to connect the second network element and the fourth network element;

and the second network unit determines that the terminal equipment is in a roaming state according to the fourth information.

13. The method according to any one of claims 8 to 12, further comprising:

the second network element receives first information from a fourth mobility management entity, wherein the fourth mobility management entity is a network element in a fourth PLMN for providing services for the terminal device, and the first information includes information of an operator to which the fourth mobility management entity belongs;

the second network element determining that a fourth PLMN serving a terminal device is not belonging to the first PLMN, comprising:

and the second network unit determines that the fourth PLMN for providing the service for the terminal equipment does not belong to the first PLMN according to the first information.

14. The method according to claim 2 or 13, characterized in that the first information comprises a globally unique access and mobility management function identity, GUAMI.

15. A method of communication, comprising:

when a terminal device moves from a first communication mode of a first Public Land Mobile Network (PLMN) to a second communication mode of a PLMN to which the terminal device belongs, a registration request message is sent to a second mobile management entity of the PLMN to which the terminal device belongs, wherein the first PLMN and the PLMN to which the terminal device belongs are different, the first communication mode is different from the second communication mode, target parameters are stored in the terminal device, and the target parameters comprise parameters of a Protocol Data Unit (PDU) session of the first communication mode mapped to parameters of the second communication mode;

The terminal device receives a registration accept message from the second mobility management entity.

16. The method of claim 15, wherein the method further comprises:

the terminal equipment determines that the first PLMN is different from the PLMN to which the terminal equipment belongs according to the first information;

the first information includes information of at least one third PLMN, which is different from the home PLMN of the terminal equipment, and the third PLMN includes the first PLMN.

17. The method of claim 16, wherein the method further comprises:

the terminal device receives the first information from the second mobility management entity.

18. The method of claim 17, wherein the first information is carried on the same message as an equivalent public land mobile network EPLMN;

wherein the EPLMN comprises at least the first PLMN.

19. The method of claim 16, wherein the method further comprises:

the terminal device receives the first information from a second network element, wherein the second network element belongs to a network element in a home PLMN of the terminal device.

20. The method according to claim 19, wherein the terminal device receives the first information from the second network element via a PDU session establishment accept message.

21. A method of communication, comprising:

the method comprises the steps that a terminal device sends a registration request message to a first mobile management entity of a first Public Land Mobile Network (PLMN), wherein the first PLMN is different from a PLMN to which the terminal device belongs;

the terminal equipment receives a registration acceptance message from the first mobile management entity;

the terminal device deletes the target parameter, or the terminal device does not generate the target parameter, or does not store the target parameter when the terminal device receives the target parameter from a second network unit, wherein the second network unit is a network unit in a PLMN to which the terminal device belongs, the target parameter includes a parameter of a protocol data unit PDU session of a first communication system mapped to a parameter of a second communication system, the communication system of the first PLMN includes the first communication system, and the communication system of the PLMN to which the terminal device belongs includes the second communication system.

22. The method of claim 21, wherein the method further comprises:

23. The method of claim 22, wherein the method further comprises:

the terminal equipment receives the first information from a second mobile management entity, wherein the second mobile management entity is a network element in a PLMN to which the terminal equipment belongs.

24. The method of claim 23, wherein the first information is carried on the same message as an equivalent public land mobile network EPLMN;

wherein the EPLMN comprises at least the first PLMN.

25. The method of claim 22, wherein the method further comprises:

26. The method according to claim 25, wherein the terminal device receives the first information from the second network element via a PDU session establishment accept message.

27. A communication device comprising means for performing the method of any one of claims 1 to 14, or means for performing the method of any one of claims 15 to 20, or means for performing the method of any one of claims 21 to 26.

28. A communication device, comprising: a processor and a memory, the processor and the memory being coupled, the memory storing program instructions that when executed by the processor, implement the method of any one of claims 1 to 14, or the method of any one of claims 15 to 20, or the method of any one of claims 21 to 26.

29. A chip comprising a processor and an input-output interface for receiving signals from or transmitting signals from other communication devices than the communication device to the processor, the processor being configured to implement the method of any one of claims 1 to 14, or to implement the method of any one of claims 15 to 20, or to implement the method of any one of claims 21 to 26, by logic circuitry or execution of code instructions.

30. A computer readable storage medium, characterized in that the storage medium has stored therein a computer program or instructions which, when executed by a communication device, implements the method of any one of claims 1 to 14, or implements the method of any one of claims 15 to 20, or implements the method of any one of claims 21 to 26.