CN112399512A

CN112399512A - Method and device for moving among communication systems

Info

Publication number: CN112399512A
Application number: CN202011150362.0A
Authority: CN
Inventors: 金辉; 欧阳国威; 窦凤辉; 杨皓睿; 李小娟
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2017-08-17
Filing date: 2017-08-17
Publication date: 2021-02-23
Anticipated expiration: 2037-08-17
Also published as: CN114710813B; CN114710813A; CN110140385B; CN112399512B; WO2019033369A1; CN110140385A

Abstract

The embodiment of the application provides a method and a device for moving among communication systems, relates to the technical field of communication, and solves the problem of prolonged processing time in the moving process of UE in the prior art. The method comprises the following steps: user Equipment (UE) establishes at least one PDN connection in a first communication system; the UE generates first PDU session state information, wherein the first PDU session state information is used for indicating that the at least one PDN connection supports the PDU session corresponding to the PDN connection moved to a second communication system; the UE sends a registration message to core network equipment of the second communication system, wherein the registration message comprises the session state information of the first PDU; and the UE receives a registration acceptance message sent by core network equipment of the second communication system so as to realize that the UE moves from the first communication system to the second communication system.

Description

Method and device for moving among communication systems

Technical Field

The present application relates to the field of communications technologies, and in particular, to a method and an apparatus for moving between communication systems.

Background

With the rapid development of communication technologies, a variety of User Equipment (UE) devices such as smart phones, tablet computers, and portable devices have appeared, and these UE devices can simultaneously support different generations of mobile communication networks and can switch between different generations of mobile communication networks. The fifth Generation (5G) mobile communication technology is an extension of the fourth Generation (4G) mobile communication technology, and has the characteristics of high performance, low delay, high capacity and the like, and the maximum data transmission speed can reach more than tens of Gbps, which is 1000 times faster than that of the existing 4G network.

In the prior art, a UE may establish a Protocol Data Network (PDN) connection in a 4G Network, and when the UE needs to be switched to a 5G Network, a Mobility Management Entity (MME) in the 4G Network may send Context (Context) information of the UE to an Access and Mobility Management Function (AMF) of the 5G Network, where the Context information includes PDN connection information established by the UE in the 4G Network, and the PDN connection information includes an IP address of a PDN Gateway (PGW). And after receiving the context information, the AMF sends a switching process to the PGW indicated by the IP address so as to switch the UE to the 5G network.

However, due to the difference of PDN gateways in 4G and 5G networks, some PDN connections may be switched to the 5G network and some PDN connections may not be switched to the 5G network. When the PDN connection cannot be switched to the 5G network, the handover procedure sent by the AMF to the PGW indicated by the IP address is not reachable, which causes the AMF to wait for a long time, thereby increasing the processing delay for the UE to move to the 5G network.

Disclosure of Invention

Embodiments of the present application provide a method and an apparatus for moving between communication systems, which are used to move a UE from a first communication system to a second communication system, and solve the problem in the prior art that a processing delay is long in a UE moving process.

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

in a first aspect, a method for moving between communication systems is provided, the method including: user Equipment (UE) establishes at least one PDN connection in a first communication system, for example, the first communication system is a 4G communication system; the UE generates first PDU session status information, where the first PDU session status information is used to indicate that the at least one PDN connection supports a PDU session corresponding to a PDN connection moved to a second communication system, and optionally, the first PDU session status information is an identifier of the PDU session; the UE sends a registration message to a core network device of a second communication system, where the registration message includes session state information of a first PDU (for example, the second communication system is a 5G communication system, and the core network device is an access and mobility management function AMF in the 5G); the UE receives a registration acceptance message sent by core network equipment of a second communication system.

In the above technical solution, the UE generates the first PDU session status information through the PDN connection supporting the move to the second communication system in at least one PDN, and sends the first PDU session status information to the core network device of the second communication system through the registration message, so that the core network device of the second communication system sends the registration acceptance message to the UE, thereby moving the UE from the first communication system to the second communication system based on the PDU session corresponding to the PDN connection supporting the move to the second communication system, and avoiding the problem of extension during the process of the move due to the unreachable PDN gateway in the move process.

In a first possible implementation manner of the first aspect, the UE establishing at least one PDN connection within a first communication system, includes: the UE sends a first message to a core network device of the first communication system (for example, the core network device is a mobility management entity MME in a 4G network), where the first message is used for the UE to establish a PDN connection in the first communication system, and optionally, the first message may be an attach request or a PDN connection request; the UE receives first information for the UE to determine that the PDN connection supports or does not support moving to the second communication system, which may be included in an attach accept message or a PDN connection accept message. In the possible implementation manner, the UE may obtain information that each PDN connection supports or does not support moving to the second communication system in the PDN connection establishment process, so that the UE may accurately determine, based on the information, a PDN connection that supports moving to the second communication system from at least one PDN connection.

In a first possible implementation manner of the first aspect, the generating, by the UE, first PDU session status information includes: the UE generates first PDU session state information using an identification of a PDU session corresponding to a PDN connection supporting movement to a second communication system. In the possible implementation manner, the UE may generate the first PDU session status information through the identifier of the corresponding PDU session, so that the PDU session may be indicated simply and effectively through the identifier.

In a first possible implementation manner of the first aspect, the generating, by the UE, first PDU session status information using an identifier of a PDU session corresponding to a PDN connection supporting moving to a second communication system includes: the UE obtains the identification of the PDU session according to the identification of the PDN connection supporting the movement to the second communication system. Optionally, the identifier of the PDN connection is processed according to a certain rule to obtain an identifier of a PDU session corresponding to the identifier, and the identifier of the PDN connection is increased or decreased by a fixed value to obtain the identifier of the corresponding PDN session.

In a first possible implementation manner of the first aspect, the obtaining, by the UE, an identifier of a PDU session according to an identifier of a PDN connection supporting moving to the second communication system includes: and the UE sets the identifier of the PDN connection supporting the movement to the second communication system as the identifier of the PDU session, namely, the identifier of the PDN connection is used as the identifier of the corresponding PDU session. In the foregoing possible implementation manners, several methods for generating an identifier of a PDU session corresponding to a PDN connection based on the identifier of the PDN connection are provided.

In a first possible implementation manner of the first aspect, the first information includes first indication information, where the first indication information is used to indicate that the PDN connection of the UE supports moving to the second communication system, and the method further includes: the UE determines that the PDN connection supports moving to a second communication system according to the first indication information; or, the first information includes second indication information, where the second indication information is used to indicate that the PDN connection of the UE does not support moving to the second communication system, and the method further includes: and the UE determines that the PDN connection does not support moving to a second communication system according to the second indication information. In the foregoing possible implementation manner, the UE may simply and effectively determine that the PDN connection supports or does not support moving to the second communication system by the first information including different indication information.

In a first possible implementation manner of the first aspect, the first information includes session information of a PDU session corresponding to the PDN connection, where the session information includes at least one of the following information: session AMBR, QoS rules, SSC pattern or PDU session identity, the method further comprising: and the UE determines that the PDN connection supports moving to a second communication system according to the session information. In the foregoing possible implementation manner, an indication method is provided, that is, the UE may determine that the UE supports moving to the second communication system through session information of the PDU session included in the first information.

With reference to the first aspect, in a first possible implementation manner of the first aspect, the first information is included in a protocol configuration option PCO, where the PCO is used for a parameter for information transfer between the UE and the PDN gateway, and other devices between the UE and the PDN gateway do not resolve the PCO. In the above possible implementation, the first information is included in the PCO, so that interaction of signaling in the network can be reduced.

In a first possible implementation manner of the first aspect, before the UE generates the first PDU session status information, the method further includes: the UE determines that it needs to move from the first communication system to the second communication system, that is, when the UE is in an idle state, the UE may actively initiate a procedure of moving from the first communication system to the second communication system.

In a first possible implementation manner of the first aspect, the registration acceptance message includes second PDU session status information, where the second PDU session status information is used to indicate a PDU session used by the UE in the second communication system, that is, a PDU session used by the UE in the second communication system, which is determined by a core network device in the second communication system from a PDU session indicated by the first PDU session status information; the method further comprises the following steps: the UE deletes other PDN connections than the PDN connection corresponding to the PDU session indicated by the second PDU session status information, i.e. the UE may delete context information of PDN connections not transferred to the second communication system. In the possible implementation manner, after the UE moves to the second communication system, consistency between the connection used by the UE and the stored context information can be ensured by deleting the context information of the PDN connection that is not transferred to the second communication system, and a certain storage space can be saved.

In a first possible implementation manner of the first aspect, the first communication system is a fourth generation 4G communication system, and the second communication system is a fifth generation 5G communication system.

In a second aspect, a method for moving between communication systems is provided, the method comprising: the method comprises the steps that core network equipment of a first communication system determines that User Equipment (UE) needs to move to a second communication system; the core network equipment of the first communication system sends context information supporting PDN connection moved to the second communication system on the UE to the core network equipment of the second communication system, wherein the context information of the PDN connection is used for the core network equipment of the second communication system to establish PDU conversation corresponding to the PDN connection, so that when the UE moves from the first communication system to the second communication system, the core network equipment of the second communication system establishes the PDU conversation corresponding to the PDN connection in the second communication system according to the context information of the PDN connection.

In the above technical solution, after determining that the UE needs to move to the second communication system, the core network device of the first communication system sends the context information supporting the PDN connection moved to the second communication system on the UE to the core network device of the second communication system, so that the core network device of the second communication system establishes the PDU session corresponding to the PDN connection, and thus the UE moves from the first communication system to the second communication system based on the PDU session corresponding to the PDN connection supporting the PDN connection moved to the second communication system, thereby avoiding a problem of extension during processing in a moving process due to the unreachable PDN gateway in the moving process.

In a first possible implementation manner of the second aspect, before the core network device of the first communication system sends the context information supporting the PDN connection moved to the second communication system on the UE to the core network device of the second communication system, the method further includes: a core network device of a first communication system determines whether a PDN connection supports or does not support movement to a second communication system. Optionally, the core network device of the first communication system may obtain, during the PDN connection establishment process, information that each PDN connection supports or does not support moving to the second communication system, so as to determine, based on the information, that the PDN connection to the second communication system is supported by the UE.

In a first possible implementation manner of the second aspect, determining, by a core network device of a first communication system, that a user equipment UE needs to move to a second communication system includes: a core network device of a first communication system receives a switching request sent by a base station; and the core network equipment of the first communication system determines that the UE needs to be moved to the second communication system according to the switching request. In the foregoing possible implementation manner, when the UE is in the connected state, the base station of the first communication system may send a handover request to the core network device of the first communication system, so as to handover the UE from the first communication system to the second communication system.

In a first possible implementation manner of the second aspect, the method further includes: and the core network equipment of the first communication system deletes the PDN connection which does not support moving to the second communication system on the UE. In the foregoing possible implementation manner, after the UE moves to the second communication system, the first communication system may delete the PDN connection that is not transferred to the second communication system, so that a certain transmission resource may be saved.

In a first possible implementation manner of the second aspect, determining, by a core network device of a first communication system, that a user equipment UE needs to move to a second communication system includes: receiving a context request message by core network equipment of a first communication system; and the core network equipment of the first communication system determines that the UE needs to move to the second communication system according to the fact that the sender of the context request message belongs to the second communication system. In the foregoing possible implementation manner, the core network device of the first communication system may determine that the UE needs to move to the second communication system by using that the sender of the context request message belongs to the second communication system.

In a first possible implementation manner of the second aspect, the context request message includes second information, and the second information is used to indicate that a sender of the context request message belongs to the second communication system; or, the context request message includes a GUTI of the UE, and the method further includes: the core network device of the first communication system determines that the sender of the context request message belongs to the second communication system based on the GUTI of the UE being mapped from the GUTI of the second communication system. In the possible implementation manner, the core network device of the first communication system may quickly and accurately determine that the sender belongs to the second communication system through the information in the context request message.

In a first possible implementation manner of the second aspect, the method further includes: the core network equipment of the first communication system determines that the UE does not support PDN connection moved to the second communication system, and sends a session deletion request which comprises an operation indication mark. In the possible implementation manner, the operation indication mark is included in the session deletion request to indicate that the receiver of the session deletion request deletes the corresponding connection, so that certain network resources can be saved.

In a first possible implementation manner of the second aspect, the first communication system is a fourth generation 4G communication system, and the second communication system is a fifth generation 5G communication system.

In a third aspect, a method for moving between systems is provided, the method including: a first core network device (such as an access and mobility management function (AMF) in a 5G communication system) of a second communication system acquires an address of a PDN gateway corresponding to a PDN connection of User Equipment (UE) in the first communication system; the first core network device sends first information to a second core network device (such as a network storage function entity (NRF)) of the second communication system, wherein the first information comprises an address of a PDN gateway; the first core network equipment receives second information sent by the second core network equipment, wherein the second information is used for indicating that the address of the PDN gateway is reachable or unreachable; and when the address of the PDN gateway is reachable, the first core network device sends context information of PDN connection to the PDN gateway, wherein the context information of the PDN connection is used for the PDN gateway to establish a PDU session corresponding to the PDN connection in the second communication system, so that the UE is moved from the first communication system to the second communication system.

In the above technical solution, after acquiring an address of a PDN gateway corresponding to a PDN connection of the UE in the first communication system, the first core network device sends context information of the PDN connection to the PDN gateway only when determining that the address of the PDN gateway is reachable, so that the PDN gateway establishes a PDU session corresponding to the PDN connection in the second communication system, so that the UE moves from the first communication system to the second communication system, thereby avoiding a problem of processing time extension in the moving process due to the unreachable PDN gateway in the moving process.

In a first possible implementation manner of the third aspect, the obtaining, by the first core network device, an address of a PDN gateway corresponding to a PDN connection of the UE in the first communication system includes: the first core network device receives context information of the PDN connection of the UE in the first communication system (for example, the context information may be sent by a mobility management entity MME in the 4G communication system to an AMF); the first core network device obtains an address of the PDN gateway corresponding to the PDN connection according to the context information, that is, the context information includes the address of the PDN gateway corresponding to the PDN connection, where the address may be an IP address or a full-name domain FQDN. In the foregoing possible implementation manner, the first core network device may obtain an address of the corresponding PDN gateway through context information of the PDN connection.

In a first possible implementation manner of the third aspect, before the first core network device sends the first information to the second core network device of the second communication system, the method further includes: the first core network equipment judges whether the address of the PDN gateway is reachable; correspondingly, the first core network device sends the first information to the second core network device of the second communication system, specifically: and when the address of the PDN gateway is not reachable, the first core network equipment sends first information to the second core network equipment.

In a first possible implementation manner of the third aspect, the method further includes: the first core network equipment judges whether the UE is in a roaming state or not according to the address of the PDN gateway; wherein the first information further includes a Data Network Name (DNN) and a Public Land Mobile Network (PLMN) identity when the UE is in a roaming state. In the foregoing possible implementation manner, the first core network device may send, when the UE is in the roaming state, the DNN and the PLMN identifier of the network where the UE is located to the second core network device, so that the second core network device determines the roaming location where the UE is located.

In a first possible implementation manner of the third aspect, the second information further includes an address of a v-SMF, and the v-SMF is a session management network element when the UE is roaming. In the foregoing possible implementation manner, when the UE is in the roaming state, the second core network device may further send the address of the v-SMF where the UE is in the roaming location to the first core network device, so that the first core network device communicates with the PDN gateway corresponding to the PDN connection through the v-SMF.

In a first possible implementation manner of the third aspect, after the first core network device sends context information of the PDN connection to the PDN gateway, the method further includes: a first core network device receives an EPS bearing identification set which is included in PDN connection and sent by a PDN gateway; and the first core network equipment generates EPS bearing establishment information according to the identification set of the EPS bearing, and sends the EPS bearing establishment information to the core network equipment of the first communication system, wherein the EPS bearing establishment information is used for the core network equipment of the first communication system to determine the EPS bearing successfully switched by the UE. In the foregoing possible implementation manner, the first core network device may notify the core network device of the first communication system of the EPS bearer successfully switched by the UE through the EPS bearer establishment information.

In a first possible implementation manner of the third aspect, the first communication system is a fourth generation 4G communication system, and the second communication system is a fifth generation 5G communication system.

In a fourth aspect, a User Equipment (UE) is provided, the UE comprising: a processing unit for establishing at least one PDN connection within a first communication system; the processing unit is further configured to generate first PDU session state information, where the first PDU session state information is used to indicate that the at least one PDN connection supports a PDU session corresponding to a PDN connection moved to a second communication system; a sending unit, configured to send a registration message to a core network device of a second communication system, where the registration message includes session state information of a first PDU; and the receiving unit is used for receiving the registration receiving message sent by the core network equipment of the second communication system.

In a first possible implementation manner of the fourth aspect, the sending unit is further configured to: sending a first message to core network equipment of a first communication system, wherein the first message is used for establishing PDN connection in the first communication system; and the receiving unit is further used for receiving first information, and the first information is used for the UE to determine that the PDN connection supports or does not support moving to the second communication system.

In a first possible implementation manner of the fourth aspect, the processing unit is further configured to: first PDU session state information is generated using an identification of a PDU session corresponding to a PDN connection supporting movement to a second communication system.

In a first possible implementation manner of the fourth aspect, the processing unit is further specifically configured to: setting an identifier supporting the PDN connection moved to the second communication system as an identifier of the PDU session; or, obtaining the identification of the PDU session according to the identification of the PDN connection supporting the movement to the second communication system.

In a first possible implementation manner of the fourth aspect, the first information includes first indication information, where the first indication information is used to indicate that the PDN connection of the UE supports moving to the second communication system, and the processing unit is further configured to: determining that the PDN connection supports moving to a second communication system according to the first indication information; or, the first information includes second indication information, where the second indication information is used to indicate that the PDN connection of the UE does not support moving to the second communication system, and the processing unit is further configured to: and determining that the PDN connection does not support moving to the second communication system according to the second indication information.

In a first possible implementation manner of the fourth aspect, the first information includes session information of a PDU session corresponding to the PDN connection, and the session information includes at least one of the following information: session AMBR, QoS rules, SSC pattern or PDU session identification, the processing unit further configured to: and determining that the PDN connection supports moving to the second communication system according to the session information.

With reference to the fourth aspect, in a first possible implementation manner of the fourth aspect, the first information is included in a protocol configuration option PCO.

In a first possible implementation manner of the fourth aspect, the processing unit is further configured to: a need to move from a first communication system to a second communication system is determined.

In a first possible implementation manner of the fourth aspect, the registration acceptance message includes second PDU session status information, where the second PDU session status information is used to indicate a PDU session used by the UE in the second communication system, and the processing unit is further configured to: deleting other PDN connections except the PDN connection corresponding to the PDU session indicated by the second PDU session state information.

In a first possible implementation manner of the fourth aspect, the first communication system is a fourth generation 4G communication system, and the second communication system is a fifth generation 5G communication system.

In a fifth aspect, a core network device is provided, where the core network device is a core network device of a first communication system, and includes: the processing unit is used for determining that the user equipment UE needs to move to a second communication system; and the sending unit is used for sending context information supporting PDN connection moved to the second communication system on the UE to core network equipment of the second communication system, wherein the context information of the PDN connection is used for establishing a PDU session corresponding to the PDN connection by the core network equipment of the second communication system, so that when the UE moves from the first communication system to the second communication system, the core network equipment of the second communication system establishes the PDU session corresponding to the PDN connection in the second communication system according to the context information of the PDN connection.

In a first possible implementation manner of the fifth aspect, before the sending unit sends the context information supporting the PDN connection moved to the second communication system on the UE to the core network device of the second communication system, the processing unit is further configured to: it is determined whether the PDN connection supports or does not support moving to the second communication system.

In a first possible implementation manner of the fifth aspect, the core network device further includes: a receiving unit, configured to receive a handover request sent by a base station; and the processing unit is further used for determining that the UE needs to be moved to the second communication system according to the switching request.

In a first possible implementation manner of the fifth aspect, the processing unit is further configured to: deleting the PDN connection on the UE that does not support moving to the second communication system.

In a first possible implementation manner of the fifth aspect, the receiving unit is further configured to receive a context request message; and the processing unit is further configured to determine that the UE needs to move to the second communication system according to that the sender of the context request message belongs to the second communication system.

In a first possible implementation manner of the fifth aspect, the context request message includes second information, where the second information is used to indicate that a sender of the context request message belongs to the second communication system; or, the context request message includes a GUTI of the UE, and the processing unit is further configured to: the core network device of the first communication system is mapped from the GUTI of the second communication system according to the GUTI of the UE, and indeed the sender of the context request message belongs to the second communication system.

In a first possible implementation manner of the fifth aspect, the processing unit is further configured to: determining that the UE does not support a PDN connection moving to a second communication system; and the sending unit is also used for sending a session deletion request, and the session deletion request comprises an operation indication mark.

In a first possible implementation manner of the fifth aspect, the first communication system is a fourth generation 4G communication system, and the second communication system is a fifth generation 5G communication system.

A sixth aspect provides a core network device, where the core network device is a first core network device of a second communication system, and the core network device includes: an obtaining unit, configured to obtain an address of a PDN gateway corresponding to a PDN connection of a user equipment UE in a first communication system; a sending unit, configured to send first information to a second core network device of a second communication system, where the first information includes an address of a PDN gateway; the acquiring unit is further configured to receive second information sent by a second core network device, where the second information is used to indicate that an address of the PDN gateway is reachable or unreachable; and the sending unit is further configured to send, when the address of the PDN gateway is reachable, context information of the PDN connection to the PDN gateway, where the context information of the PDN connection is used for the PDN gateway to establish a PDU session corresponding to the PDN connection in the second communication system, so as to implement that the UE moves from the first communication system to the second communication system.

In a first possible implementation manner of the sixth aspect, the obtaining unit is further configured to: receiving context information of a PDN connection established by the UE in a first communication system; and acquiring the address of the PDN gateway corresponding to the PDN connection according to the context information.

In a first possible implementation manner of the sixth aspect, before the sending unit sends the first information to the second core network device of the second communication system, the core network device further includes: the processing unit is used for judging whether the address of the PDN gateway is reachable or not; correspondingly, the sending unit is further specifically configured to send the first information to the second core network device when the address of the PDN gateway is not reachable.

In a first possible implementation manner of the sixth aspect, the processing unit is further configured to: judging whether the UE is in a roaming state or not according to the address of the PDN gateway; wherein the first information further includes a Data Network Name (DNN) and a Public Land Mobile Network (PLMN) identity when the UE is in a roaming state.

In a first possible implementation manner of the sixth aspect, the second information further includes an address of a v-SMF, and the v-SMF is a session management network element when the UE is roaming.

In a first possible implementation manner of the sixth aspect, after the sending unit sends the context information of the PDN connection to the PDN gateway, the obtaining unit is further configured to receive an identifier set of an EPS bearer included in the PDN connection sent by the PDN gateway; the processing unit is further configured to generate EPS bearer establishment information according to the identifier set of the EPS bearer; and the sending unit is further configured to send EPS bearer establishment information, where the EPS bearer establishment information is used by the core network device of the first communication system to determine an EPS bearer to which the UE is successfully switched.

A seventh aspect of the present application provides a user equipment, where the user equipment includes a memory, a processor, a communication interface, and a bus, where the memory stores codes and data, the processor, the memory, and the communication interface are connected through the bus, and the processor executes the codes in the memory to enable the user equipment to perform the inter-communication-system mobility method provided in the first aspect or any possible implementation manner of the first aspect.

An eighth aspect of the present application provides a core network device, where the core network device is a core network device of a first communication system, and the core network device includes: the mobile communication system comprises a memory, a processor, a communication interface and a bus, wherein the memory stores codes and data, the processor, the memory and the communication interface are connected through the bus, and the processor runs the codes in the memory to enable the core network device to execute the inter-communication-system mobile method provided by the second aspect or any possible implementation manner of the second aspect.

A ninth aspect of the present application provides a core network device, where the core network device is a core network device of a second communication system, and the core network device includes: the core network device comprises a memory, a processor, a communication interface and a bus, wherein the memory stores codes and data, the processor, the memory and the communication interface are connected through the bus, and the processor runs the codes in the memory to enable the core network device to execute the inter-communication-system moving method provided by the third aspect or any possible implementation manner of the third aspect.

In a tenth aspect, there is provided a method of inter-communication system mobility, the method comprising: user Equipment (UE) establishes at least one PDN connection in a first communication system; the UE generates first PDU session state information, wherein the first PDU session state information is used for indicating that the at least one PDN connection supports a PDU session corresponding to a PDN connection moved to a second communication system, and the first communication system and the second communication system are communication systems of different generations; the UE sends a registration message to core network equipment of the second communication system, wherein the registration message comprises the session state information of the first PDU; and the UE receives a registration acceptance message sent by the core network equipment of the second communication system.

In a first possible implementation manner of the tenth aspect, the UE establishing at least one PDN connection within a first communication system, includes: the UE sends a first message to core network equipment of a first communication system, wherein the first message is used for establishing PDN connection in the first communication system by the UE; the UE receives first information, wherein the first information is used for the UE to determine that the PDN connection supports or does not support moving to the second communication system.

In a first possible implementation manner of the tenth aspect, the method further includes: and the UE distributes a PDU session identifier in the process of establishing the PDN connection and sends the PDU session identifier to a PDN gateway corresponding to the PDN connection.

In a first possible implementation manner of the tenth aspect, the generating, by the UE, first PDU session status information includes: and the UE uses the identifier of the PDU session corresponding to the PDN connection supporting the movement to the second communication system to generate the first PDU session state information.

In a first possible implementation manner of the tenth aspect, the first information includes first indication information, where the first indication information is used to indicate that the PDN connection of the UE supports moving to the second communication system, and the method further includes: the UE determines that the PDN connection supports moving to the second communication system according to the first indication information; or, the first information includes second indication information, where the second indication information is used to indicate that the PDN connection of the UE does not support moving to the second communication system, and the method further includes: and the UE determines that the PDN connection does not support moving to the second communication system according to the second indication information.

In a first possible implementation manner of the tenth aspect, the first information includes session information of a PDU session corresponding to the PDN connection, and the session information includes at least one of the following information: a session AMBR, QoS rules, SSC pattern or PDU session identification, the method further comprising: and the UE determines that the PDN connection supports moving to the second communication system according to the session information.

In a first possible implementation manner of the tenth aspect, the first information is included in a protocol configuration option PCO.

In a first possible implementation manner of the tenth aspect, before the UE generates the first PDU session status information, the method further includes: the UE determines that a move from the first communication system to the second communication system is required.

In a first possible implementation manner of the tenth aspect, the registration accept message includes second PDU session status information, where the second PDU session status information is used to indicate a PDU session used by the UE in the second communication system, and the method further includes: and the UE deletes other PDN connections except the PDN connection corresponding to the PDU session indicated by the second PDU session state information.

In a first possible implementation manner of the tenth aspect, the first communication system is a fourth generation 4G communication system, and the second communication system is a fifth generation 5G communication system.

In a first possible implementation manner of the tenth aspect, the first PDU session status information includes: and indicating that the PDU session identification is respectively a value corresponding to 0-15, the PDU session identification corresponding to the PDN connection supporting the movement to the second communication system is 1, and other corresponding values are 0.

In an eleventh aspect, there is provided an inter-communication system mobility method, the method including: the method comprises the steps that first core network equipment receives context information of PDN connection established in a first communication system by User Equipment (UE), wherein the context information of the PDN connection is sent by the core network equipment in the first communication system; the first core network equipment sends the context information of the PDN connection to a PDN gateway corresponding to the PDN connection, wherein the context information of the PDN connection is used for the PDN gateway to establish a PDU session corresponding to the PDN connection in a second communication system so as to realize that the UE moves from the first communication system to the second communication system; the first core network equipment receives an identification set of EPS (evolved packet system) load contained in the PDN connection sent by a PDN gateway corresponding to the PDN connection; and the first core network equipment generates an EPS bearer establishment list according to the identification set of the EPS bearer, and sends the EPS bearer establishment list to the core network equipment of the first communication system, wherein the EPS bearer establishment list is used for the core network equipment of the first communication system to determine that the UE successfully switches the EPS bearer of the second communication system.

In a first possible implementation manner of the eleventh aspect, the sending, by the first core network device, context information of the PDN connection to a PDN gateway corresponding to the PDN connection further includes: the first core network equipment sends first information to second core network equipment of the second communication system, wherein the first information comprises an address of the PDN gateway; and the first core network equipment receives second information sent by the second core network equipment, and sends context information of the PDN connection to the PDN gateway according to the second information.

In a first possible implementation manner of the eleventh aspect, the method further includes: and the first core network equipment acquires the address of the PDN gateway corresponding to the PDN connection according to the context information of the PDN connection.

In a first possible implementation manner of the eleventh aspect, the sending, by the first core network device, context information of the PDN connection to a PDN gateway corresponding to the PDN connection includes: the first core network equipment sends context information corresponding to PDN connection to a plurality of PDN gateways corresponding to the PDN connection; the receiving, by the first core network device, an identifier set of an EPS bearer included in the PDN connection sent by a PDN gateway corresponding to the PDN connection includes: the first core network equipment receives an identification set of EPS (evolved packet System) bearers included in a plurality of PDN connections sent by a plurality of PDN gateways; the first core network device generates an EPS bearer establishment list according to the identification set of the EPS bearer, including: and the first core network equipment generates the EPS bearing establishment list according to the identification set of EPS bearings included by the PDN connections.

In a first possible implementation manner of the eleventh aspect, the first communication system and the second communication system are different generation communication systems.

In a first possible implementation manner of the eleventh aspect, the first communication system is a fourth generation 4G communication system, and the second communication system is a fifth generation 5G communication system.

In a twelfth aspect, there is provided a user equipment, comprising: a processing unit for establishing at least one PDN connection within a first communication system; the processing unit is further configured to obtain first PDU session status information, where the first PDU session status information is used to indicate that a PDU session corresponding to a PDN connection moving to a second communication system is supported in the at least one PDN connection, and the first communication system and the second communication system are communication systems of different generations; a sending unit, configured to send a registration message to a core network device of the second communication system, where the registration message includes the session status information of the first PDU; and the receiving unit is used for receiving the registration acceptance message sent by the core network equipment of the second communication system.

In a first possible implementation manner of the twelfth aspect, the sending unit is further configured to send a first message to a core network device of a first communication system, where the first message is used to establish a PDN connection in the first communication system; the receiving unit is further configured to receive first information, where the first information is used to determine that the PDN connection supports or does not support moving to the second communication system.

In a first possible implementation manner of the twelfth aspect, the processing unit is further configured to allocate a PDU session identifier during the process of establishing the PDN connection; and the sending unit is further configured to send the PDU session identifier to a PDN gateway corresponding to the PDN connection.

In a first possible implementation manner of the twelfth aspect, the processing unit is further configured to: generating the first PDU session state information using an identification of a PDU session corresponding to a PDN connection supporting movement to a second communication system.

In a first possible implementation manner of the twelfth aspect, the first information includes first indication information, where the first indication information is used to indicate that the PDN connection of the user equipment supports moving to the second communication system, and the processing unit is further configured to: determining that the PDN connection supports moving to the second communication system according to the first indication information; or, the first information includes second indication information, where the second indication information is used to indicate that the PDN connection of the user equipment does not support moving to the second communication system, and the processing unit is further configured to: and determining that the PDN connection does not support moving to the second communication system according to the second indication information.

In a first possible implementation manner of the twelfth aspect, the first information includes session information of a PDU session corresponding to the PDN connection, and the session information includes at least one of the following information: a session AMBR, QoS rules, SSC pattern or PDU session identification, the processing unit further configured to: and determining that the PDN connection supports moving to the second communication system according to the session information.

In a first possible implementation manner of the twelfth aspect, the first information is included in a protocol configuration option PCO.

In a first possible implementation manner of the twelfth aspect, the processing unit is further configured to: determining that a move from the first communication system to the second communication system is required.

In a first possible implementation manner of the twelfth aspect, the registration acceptance message includes second PDU session status information, where the second PDU session status information is used to indicate a PDU session used by the user equipment in the second communication system, and the processing unit is further configured to: deleting other PDN connections except the PDN connection corresponding to the PDU session indicated by the second PDU session state information.

In a first possible implementation manner of the twelfth aspect, the first communication system is a fourth-generation 4G communication system, and the second communication system is a fifth-generation 5G communication system.

In a first possible implementation manner of the twelfth aspect, the first PDU session status information includes: and indicating that the PDU session identification is respectively a value corresponding to 0-15, the PDU session identification corresponding to the PDN connection supporting the movement to the second communication system is 1, and other corresponding values are 0.

In a thirteenth aspect, a core network device is provided, where the core network device serves as a first core network device, and includes: a receiving unit, configured to receive context information of a PDN connection established in a first communication system by a user equipment UE, where the context information of the PDN connection is sent by a core network device in the first communication system; a sending unit, configured to send context information of the PDN connection to a PDN gateway corresponding to the PDN connection, where the context information of the PDN connection is used for the PDN gateway to establish a PDU session corresponding to the PDN connection in a second communication system, so as to enable the UE to move from the first communication system to the second communication system; the receiving unit is further configured to receive an identifier set of an EPS bearer included in the PDN connection sent by a PDN gateway corresponding to the PDN connection; a processing unit, configured to generate an EPS bearer establishment list according to the identifier set of the EPS bearer, where the EPS bearer establishment list is used by the core network device of the first communication system to determine that the UE successfully switches an EPS bearer of a second communication system; the sending unit is further configured to send the EPS bearer establishment list to the core network device of the first communication system.

In a first possible implementation manner of the thirteenth aspect, the sending unit is further configured to send first information to a second core network device of the second communication system, where the first information includes an address of the PDN gateway; the receiving unit is further configured to receive second information sent by the second core network device, and send context information of the PDN connection to the PDN gateway according to the second information.

In a first possible implementation manner of the thirteenth aspect, the processing unit is further configured to: and acquiring the address of the PDN gateway corresponding to the PDN connection according to the context information of the PDN connection.

In a first possible implementation manner of the thirteenth aspect, the sending unit is further configured to send context information of corresponding PDN connections to a plurality of PDN gateways corresponding to the plurality of PDN connections; the receiving unit is further configured to receive an identifier set of EPS bearers included in a plurality of PDN connections sent by the plurality of PDN gateways; the processing unit is further configured to generate the EPS bearer establishment list according to an identification set of EPS bearers included in the multiple PDN connections.

In a first possible implementation manner of the thirteenth aspect, the first communication system and the second communication system are different generation communication systems.

In a first possible implementation manner of the thirteenth aspect, the first communication system is a fourth generation 4G communication system, and the second communication system is a fifth generation 5G communication system.

A further aspect of the application provides a computer program product comprising instructions which, when run on a computer, cause the computer to perform the method of the tenth aspect described above.

A further aspect of the present application provides a computer program product comprising instructions which, when run on a computer, cause the computer to perform the method of the eleventh aspect described above.

Yet another aspect of the present application provides a system comprising a user equipment, a core network entity of a first communication system and a core network entity of a second communication system; the user equipment is any one of the fourth aspect or any possible implementation manner of the fourth aspect, or the user equipment provided by the seventh aspect; and/or the core network entity of the first communication system is the core network device provided in any one of the possible implementation manners of the fifth aspect or the fifth aspect; and/or the core network entity of the second communication system is the core network device provided in any one of the possible implementation manners of the sixth aspect or the sixth aspect.

Yet another aspect of the present application provides a computer-readable storage medium having stored therein instructions, which when executed on a computer, cause the computer to perform the method of the above-described aspects.

Yet another aspect of the present application provides a computer program product containing instructions which, when run on a computer, cause the computer to perform the method of the above-described aspects.

It is understood that any one of the above-mentioned apparatuses, computer storage media or computer program products for mobile communication methods is used to execute the corresponding method provided above, and therefore, the beneficial effects achieved by the above-mentioned method can be referred to the beneficial effects in the corresponding method provided above, and are not described herein again.

Drawings

Fig. 1 is a system architecture diagram of a communication system according to an embodiment of the present application;

fig. 2 is a schematic structural diagram of a user equipment according to an embodiment of the present application;

fig. 3 is a flowchart of a method for inter-communication system mobility according to an embodiment of the present application;

fig. 4 is a flowchart of establishing a PDN connection according to an embodiment of the present application;

fig. 5 is a first exemplary diagram of a UE moving from a 4G to a 5G communication system according to an embodiment of the present application;

fig. 6 is a second exemplary diagram of a UE moving from a 4G to a 5G communication system according to an embodiment of the present application;

fig. 7 is a flowchart of another method for inter-communication system mobility according to an embodiment of the present application;

fig. 8 is a third exemplary diagram of a UE moving from a 4G to a 5G communication system according to an embodiment of the present application;

fig. 9 is a flowchart illustrating a UE moving to a second communication system according to an embodiment of the present application;

fig. 10 is a fourth exemplary diagram of a UE moving from a 4G to a 5G communication system according to an embodiment of the present application;

fig. 11 is a fifth exemplary diagram of a UE moving from a 4G to a 5G communication system according to an embodiment of the present application;

fig. 12 is a schematic structural diagram of a user equipment according to an embodiment of the present application;

fig. 13 is a schematic structural diagram of another user equipment according to an embodiment of the present application;

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

fig. 15 is a schematic structural diagram of a core network device of another first communication system according to an embodiment of the present application;

fig. 16 is a schematic structural diagram of a core network device of a second communication system according to an embodiment of the present application;

fig. 17 is a schematic structural diagram of a core network device of another second communication system according to an embodiment of the present application.

Detailed Description

Before the present application is described, terms related to embodiments of the present application will be described.

Protocol Data Network (PDN) Connection (Connection or Connectivity): in the first communication system (e.g., in the 4G network), the EPS bearers are a combination of a set of EPS bearers established on the UE, and the EPS bearers have the same IP address and Access Point Name (APN), and the EPS bearer refers to a data transmission channel in the first communication system (e.g., in the 4G network). At the UE and network side, a PDN connection is identified by an IP address and APN.

PDN connection Context (Context): including the IP address used by the PDN connection, APN, PGW address, and context information for each EPS bearer.

PDU Session (Session): within a second communication system (e.g., a 5G Network), a combination of a set of QoS flows (flows) established on the UE, the QoS flows having the same IP address and Data Network Name (DNN). A QoS flow refers to a data transmission channel within a second communication system (e.g., within a 5G network). At the UE and network side, one PDU session is identified by an IP address and DNN.

PDU session context: including the IP address, APN, SMF and UPF addresses used by the PDU session, and context information for each QoS flow.

Protocol Configuration Option (PCO): parameters for information transfer between the UE and a PDN Gateway (PGW), a Mobility Management Entity (MME) and a base station do not resolve the PCO.

Fig. 1 shows a system architecture of a communication system applied in an embodiment of the present application, where the system architecture includes a first communication system and a second communication system, and fig. 1 illustrates an example in which the first communication system is a 4G communication system and the second communication system is a 5G communication system.

Referring to fig. 1, the communication system includes a UE, an Evolved UMTS Terrestrial Radio Access Network (E-UE ran), a Mobility Management entity MME, a Serving Gateway (S-GW), a User Plane Function (User Plane Function, UPF) + a User Plane of a PDN Gateway (PDN Gateway-User Plane, PGW-U), a Session Management Function (Session Management Function, SMF) + a Control Plane of a PDN Gateway (PDN Gateway-Control Plane, PGW-C), a Policy Control Function (PCF) + a Policy and Charging Rules Function unit (Policy and Charging functions, PCRF), a Home subscription Server (Home Subscriber, HSS) + a Unified Data Management (udmanager, Data Access, Mobility Management Function (Access and Mobility Management Function, Access Gateway and Mobility Management Function (Access Network, 5G-RAN).

The E-UTRAN is a base station at the 4G side, and the UE can access a 4G communication system through the base station; the 5G-RAN is a base station on the 5G side through which the UE can access the 5G communication system, the 5G-RAN may be a base station after the E-UTRAN has further evolved, the UE may access the base station of the 5G communication system through the base station, or the 5G-RAN may be a base station dedicated for the UE to access the 5G communication system.

The MME is 4G core network equipment and is responsible for authentication, authorization, mobility management and session management of the UE; the associated EPS Bearer identity (LBI) of the UE at the PDN connection of 4G is allocated by the device.

The S-GW is a 4G core network device (core network gateway) and is responsible for data forwarding, downlink data storage and the like.

The UPF + PGW-U is core network equipment shared by the 4G and the 5G, namely core network equipment combined by the 4G and the 5G, and comprises functions of the UPF and the PGW-U. The UPF is a user plane device of a 5G core network, provides a user plane service for a PDU session of the UE, and is an interface gateway between an operator network and an external network. The PGW-U is a user plane device of a 4G core network, provides a user plane service for PDN connection of the UE, and is an interface gateway between an operator network and an external network. The UPF + PGW-U can also be called PGW-U + UPF, and the equipment is the same as the equipment as long as the equipment comprises the functions of the UPF and the PGW-U.

The SMF + PGW-C is core network equipment shared by 4G and 5G, namely core network equipment combined by 4G and 5G, and comprises functions of the SMF and the PGW-C. The SMF is control plane equipment of a 5G core network and provides control plane service for PDU conversation of the UE; and managing the PDU session of the 5G, managing the QoS of the 5G, and being responsible for allocating an IP address for the UE and selecting a UPF for the UE. The PGW-C is control plane equipment of a 4G core network and provides user plane service for PDN connection of the UE; and the UE is responsible for allocating an IP address to the UE and establishing an EPS bearer for the UE. SMF + PGW-C may also be referred to as PGW-C + SMF, and is the same as the present device as long as it includes SMF and PGW-C functionality.

The PCF + PCRF is a core network device shared by the 4G and the 5G, that is, a core network device combined by the 4G and the 5G, including the PCF and the PCRF. The PCRF is a 4G core network device and is responsible for generating a policy for a user to establish a data Bearer (Bearer). The PCF is a 5G core network device, similar to the PCRF function. The PCF + PCRF may also be referred to as PCRF + PCF, as long as the device includes PCF and PCRF functions, which are the same as the present device.

The UDM + HSS is core network equipment shared by 4G and 5G, that is, core network equipment combined by 4G and 5G, including the HSS and the UDM. The HSS is 4G core network equipment and is used for storing subscription data of a user. The SDM is 5G core network equipment, and is used to store subscription data of a user. UDM + HSS may also be referred to as HSS + UDM, as long as the device includes both HSS and UDM functionality, which is the same as the present device.

The AMF is a 5G core network device and is used for authenticating and authorizing a user and managing the mobility of the user.

The N26 interface is the interface between the MME and the AMF, which is currently optional. When the UE moves between the 4G and the 5G, the context of the UE can be transferred through an N26 interface, and when the PDN connection established by the UE in the 4G network can be seamlessly transferred to the 5G network, the MME selects a network element SMF + PGW-C combined between the 5G and the 4G for the UE, wherein the seamless transfer refers to that the IP address is unchanged and the PGW-C is unchanged.

Fig. 2 is a schematic structural diagram of a user equipment according to an embodiment of the present disclosure, where the user equipment may be a mobile phone, a tablet Computer, a notebook Computer, a UMPC (Ultra-mobile Personal Computer), a netbook, a PDA (Personal Digital Assistant), a mobile phone chip (e.g., a modem chip), a mobile station, a wearable device, a vehicle-mounted device, or a terminal device. For convenience of description, the above-mentioned devices are collectively referred to as user equipment or UE in this application. The embodiment of the present application is described by taking a UE as a mobile phone as an example, where the UE includes: RF (radio frequency) circuit 210, memory 220, input unit 230, display unit 240, gravity sensor 250, audio circuit 260, processor 270, and power supply 280. The following describes each component of the mobile phone in detail with reference to fig. 2:

the RF circuit 210 may be used for receiving and transmitting signals during information transmission and reception or during a call, and in particular, receives downlink information of a base station and then processes the received downlink information to the processor 270; in addition, the uplink data is transmitted to the base station. In general, the RF circuit 210 includes, but is not limited to, an antenna, at least one Amplifier, a transceiver, a coupler, a Low Noise Amplifier (LNA), a duplexer, and the like. In addition, the RF circuitry 210 may also communicate with networks and other devices via wireless communications. The Processor 270 may include an Application Processor (AP) and a modem Processor, where an operating system, a user interface, an Application program, and the like of the mobile phone run on the AP and communication functions are processed on the modem Processor.

The memory 220 may be used to store software programs and modules, and the processor 270 executes various functional applications and data processing of the mobile phone by operating the software programs and modules stored in the memory 220. The memory 220 may mainly include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required by at least one function (e.g., a call function, a video playing function, etc.), and the like; the storage data area may store data (e.g., a phonebook, photo album, etc.) created according to the use of the cellular phone, and the like. Further, the memory 220 may include high speed random access memory, and may also include non-volatile memory, such as at least one magnetic disk storage device, flash memory device, or other volatile solid state storage device.

The input unit 230 may be used to receive input numeric or character information and generate key signal inputs related to user settings and function control of the cellular phone. Specifically, the input unit 230 may include a touch panel 231 and other input devices 232. The touch panel 231, also referred to as a touch screen, may collect a touch operation performed by a user on or near the touch panel 231 (e.g., an operation performed by the user on or near the touch panel 231 using any suitable object or accessory such as a finger or a stylus), and drive the corresponding connection device according to a preset program. Alternatively, the touch panel 231 may include two parts of a touch detection device and a touch controller. The touch detection device detects the touch direction of a user, detects a signal brought by touch operation and transmits the signal to the touch controller; the touch controller receives touch information from the touch sensing device, converts the touch information into touch point coordinates, sends the touch point coordinates to the processor 270, and can receive and execute commands sent by the processor 270. In addition, the touch panel 231 may be implemented in various types, such as a resistive type, a capacitive type, an infrared ray, and a surface acoustic wave. The input unit 230 may include other input devices 232 in addition to the touch panel 231. In particular, other input devices 232 may include, but are not limited to, one or more of a physical keyboard, function keys (such as volume control keys, power switch keys, etc.), a trackball, a mouse, a joystick, and the like.

The display unit 240 may be used to display information input by the user or information provided to the user and various menus of the mobile phone. The Display unit 240 may include a Display panel 241, and optionally, the Display panel 241 may be configured in the form of a Liquid Crystal Display (LCD), an Organic Light-Emitting Diode (OLED), or the like. Further, the touch panel 231 may cover the display panel 241, and when the touch panel 231 detects a touch operation thereon or nearby, the touch panel is transmitted to the processor 270 to determine the type of the touch event, and then the processor 270 provides a corresponding visual output on the display panel 241 according to the type of the touch event. Although in fig. 2, the touch panel 231 and the display panel 241 are two independent components to implement the input and output functions of the mobile phone, in some embodiments, the touch panel 231 and the display panel 241 may be integrated to implement the input and output functions of the mobile phone.

The gravity sensor 250 may detect the acceleration of the mobile phone in each direction (generally, three axes), detect the gravity when the mobile phone is stationary, and may be used for applications of recognizing the posture of the mobile phone (such as horizontal and vertical screen switching, related games, magnetometer posture calibration), and vibration recognition related functions (such as pedometer and tapping). The handset may also include other sensors, such as light sensors. In particular, the light sensor may include an ambient light sensor and a proximity light sensor. The ambient light sensor can adjust the brightness of the display panel 241 according to the brightness of ambient light; the proximity light sensor may detect whether an object is near or touching the phone, and may turn off the display panel 241 and/or the backlight when the phone is moved to the ear. The mobile phone can also be provided with other sensors such as a gyroscope, a barometer, a hygrometer, a thermometer and an infrared sensor, which are not described in detail herein.

Audio circuitry 260, speaker 261, and microphone 262 may provide an audio interface between a user and a cell phone. The audio circuit 260 may transmit the electrical signal converted from the received audio data to the speaker 261, and convert the electrical signal into a sound signal by the speaker 261 and output the sound signal; on the other hand, the microphone 262 converts the collected sound signals into electrical signals, which are received by the audio circuit 260 and converted into audio data, which are then output to the RF circuit 210 for transmission to, for example, another cell phone, or to the memory 220 for further processing.

The processor 270 is a control center of the mobile phone, connects various parts of the entire mobile phone by using various interfaces and lines, and performs various functions of the mobile phone and processes data by operating or executing software programs and/or modules stored in the memory 220 and calling data stored in the memory 220, thereby integrally monitoring the mobile phone. Alternatively, processor 270 may include one or more processing units; preferably, the processor 270 may integrate an application processor, which mainly handles operating systems, user interfaces, application programs, etc., and a modem processor, which mainly handles wireless communications. It will be appreciated that the modem processor described above may not be integrated into processor 270.

The handset also includes a power supply 280 (e.g., a battery) for powering the various components, which may preferably be logically coupled to the processor 270 via a power management system, such that the power management system may be used to manage charging, discharging, and power consumption.

Although not shown, the mobile phone may further include a WiFi module, a bluetooth module, etc., which are not described herein. Those skilled in the art will appreciate that the handset configuration shown in fig. 2 is not intended to be limiting and may include more or fewer components than those shown, or some components may be combined, or a different arrangement of components.

Fig. 3 is a flowchart of a method for moving between communication systems according to an embodiment of the present application, and referring to fig. 3, the method includes the following steps.

S301: the UE establishes at least one PDN connection within the first communication system.

Wherein the at least one PDN connection may include one or more PDN connections, and for each of the at least one PDN connections, the UE may establish the PDN connection within the first communication system by, for example, as described below.

Specifically, the UE sends a first message to a core network device of the first communication system, where the first message is used to establish a PDN connection in the first communication system, and the first message may be an attach request or a PDN connection request. When the core network device of the first communication system receives the first message, it may determine whether the PDN connection supports mobility to the second communication system. Optionally, the core network device of the first communication system may determine whether the PDN connection supports moving to the second communication system according to the capability reported by the UE during registration, subscription data of the UE, and the like. The core network device of the first communication system saves information that the PDN connection supports or does not support moving to the second communication system. A PDN connection supporting network interworking may be understood as the PDN connection may be moved (Move or Transfer) from a first communication system to a second communication system. Namely, a PDU session corresponding to the PDN connection is established in the second communication system, and the PDN connection and the PDU session meet one or more of the following conditions: the IP address of the PDU session is the same as the IP address of the PDN connection, the PDU session is the same as the PDN gateway of the PDN connection, the DNN used for the PDU session corresponds to the APN used for the PDN connection, or the context of the PDU session corresponds to the context of the PDN connection.

And when the PDN connection is determined to support moving to the second communication system, the core network equipment of the first communication system selects a PDN gateway jointly arranged by the first communication system and the second communication system. And the core network equipment of the first communication system sends a session creation request to the PDN gateway and receives a session creation response returned by the PDN gateway. The session creation response returned by the PDN gateway may contain the first information. Then, the core network device of the first communication system may send the first information to the UE, so that the UE receives the first information, where the first information is used for the UE to determine that the PDN connection supports or does not support moving to the second communication system, that is, the first information is used to notify the UE that the current PDN connection supports or does not support Interworking (Interworking). The first information received by the UE may be sent by a PDN gateway (e.g., PGW), or may be sent by a core network device (e.g., AMF) in the second communication system.

The first information may include first indication information, where the first indication information is used to indicate that the PDN connection of the UE supports moving to the second communication system. Correspondingly, when the UE receives the first information, it may be determined that the PDN connection supports moving to the second communication system according to the first indication information; or, the first information includes second indication information, where the second indication information is used to indicate that the PDN connection of the UE does not support moving to the second communication system, and correspondingly, when the UE receives the first information, it may be determined that the PDN connection does not support moving to the second communication system according to the second indication information. The PDN connection may be explicitly indicated by the first indication information or the second indication information as supporting or not supporting the move to the second communication system. In a specific implementation, the first indication information and the second indication information may be the same parameter, and are distinguished by different values; alternatively, the first indication information and the second indication information may be different parameters.

Alternatively, the first information may include session information of a PDU session corresponding to the PDN connection, the session information including at least one of the following information: a Session Aggregated Maximum Bit Rate (AMBR), QoS rules, a traffic and Session Continuity (SSC) pattern of a PDU Session, or a PDU Session identity. Correspondingly, when the UE receives the first information, it may be determined that the PDN connection supports moving to the second communication system according to that the first information includes the session information. When the session information is not included in the first information, it may be determined that the PDN connection does not support moving to the second communication system. Whether the first information includes the session information may indicate that the PDN connection supports or does not support moving to a second communication system.

Optionally, the first information may be included in the protocol configuration option PCO. The first communication system may be a fourth generation (4G) communication system, the second communication system may be a fifth generation (5G) communication system, the core network device of the first communication system may be an MME, and fig. 3 illustrates an MME as an example.

Taking the 4G and 5G communication systems shown in fig. 1 as examples, if the core network device of the first communication system is an MME and the PDN gateway is an SMF + PGW-C, a procedure of the UE establishing a PDN connection in the 4G communication system may be as shown in fig. 4. The method specifically comprises the following steps: s401, the UE sends an attachment request or a PDN connection request to an MME; s402, the MME selects SMF + PGW-C combined with 4G and 5G when determining that the PDN connection can be moved to 5G; s403.MME sends a request for creating session to S-GW; s404, the S-GW sends a session creation request to the SMF + PGW-C; s405, SMF + PGW-C sends a session creating response to S-GW, wherein the session creating response contains PCO, and the PCO contains information for informing the UE that the current PDN connection supports network intercommunication; s406. the S-GW forwards the session creating response to the MME; s407, the MME stores the information that the PDN connection supports network intercommunication; and S408, the MME sends an attachment acceptance message or a PDN connection acceptance message containing a PCO to the UE, wherein the PCO contains information for informing the UE that the current PDN connection supports network intercommunication, so that the PDN connection is established, and meanwhile, the UE can also store the information that the PDN connection supports network intercommunication. Fig. 4 illustrates an example in which the PDN connection supports network interworking, and an eNB is a base station in a 4G communication system.

S302: the UE generates first PDU session state information, wherein the first PDU session state information is used for indicating that at least one PDN connection supports the PDU session corresponding to the PDN connection moved to the second communication system.

The UE may generate first PDU Session Status information using the identifier of the PDU Session corresponding to the PDN connection supporting the move to the second communication system, that is, the UE may obtain a Session identifier list supporting the PDU Session corresponding to the PDN connection supporting the move to the second communication system in at least one PDN connection, and generate first PDU Session Status information (PDU Session Status) using the Session identifier list. The first PDU session status information is used to indicate that a PDU session corresponding to a PDN connection moving to a second communication system is supported on the UE. The first PDU session status information may include only an identification of a PDU session corresponding to a PDN connection supporting movement to the second communication system; or, in a bitmap (bitmap), setting a bit of the PDU session identifier corresponding to the PDN connection supporting the move to the second communication system to 1, and setting other bits to 0, where the PDU session identifiers shown in table 1 are respectively 0 to 15, and the corresponding values are specifically shown in table 1. In table 1 below, the PDU session identifier 5 and the PDU session identifier 7 correspond to a value of 1, which indicates that there is a corresponding PDU session, and the other values are 0, which indicates that there is no corresponding PDU session identifier.

TABLE 1

PDU session identification	7	6	5	4	3	2	1	0
									Value taking	1	0	1	0	0	0	0	0
PDU session identification	15	14	13	12	11	10	9	8
									Value taking	0	0	0	0	0	0	0	0

When the UE acquires the session identifier list of the PDU session corresponding to the PDN connection supporting the move to the second communication system, the UE may set the identifier supporting the PDN connection moving to the second communication system as the session identifier of the PDU session corresponding thereto. Or, the UE maps and obtains the session identifier of the PDU session corresponding to the UE in some manner according to the identifier of the PDN connection supporting the move to the second communication system. For example, the UE directly sets the PDN connection identity as a PDU session identity; the UE increases or decreases the PDN connection identifier by a specific value to obtain a PDU session identifier; or, in the process of establishing the PDN connection by the UE, the UE distributes the PDU session identification and sends the PDU session identification to the SMF + PGW-C, the SMF + PGW-C returns to the UE for confirmation through the PCO, and the UE locally saves the corresponding relation between the PDN connection identification and the PDU session identification; or, in the process of establishing the PDN connection, the SMF + PGW-C requests the AMF to allocate a PDU session identifier, the SMF + PGW-C sends the PDU session identifier to the UE through the PCO, and the UE locally stores the correspondence between the PDN connection identifier and the PDU session identifier.

In addition, when the UE determines that the PDN connection moved to the second communication system is supported in at least one PDN connection, the UE may determine through the information of whether the PDN connection supports network interworking or not, which is stored in fig. 4. If a PDN connection supports network interworking, the PDN connection supports moving to a second communication system; if one PDN connection does not support network intercommunication, the PDN connection does not support moving to a second communication system.

Further, before the UE generates the first PDU session status information, the method may further include: the UE determines that it needs to move from the first communication system to the second communication system, that is, when the UE is in an Idle state (Idle), the UE may actively initiate a procedure of moving from the first communication system to the second communication system, so as to obtain a higher network service.

S303: the UE sends a Registration (Registration) message to a core network device of the second communication system, where the Registration message includes session state information of the first PDU.

When the UE generates the first PDU session status information, the UE may send a registration message to the core network device of the second communication system, and send the first PDU session status information to the core network device of the second communication system through the registration message, so that the core network device of the second communication system returns a registration acceptance message to the UE.

When the second communication system is a 5G communication system, the core network device of the second communication system may be an AMF, that is, a core network device in the second communication system for managing the mobility of the user, and the core network device of the second communication system is exemplified as the AMF in fig. 3.

S304: the UE receives a registration acceptance message sent by core network equipment of the second communication system so as to realize that the UE moves from the first communication system to the second communication system.

When the UE receives the registration acceptance message, the UE already moves from the first communication system to the second communication system, and because the UE is based on the PDU session corresponding to the PDN connection supporting the movement to the second communication system in at least one PDN connection, the UE sends the registration message to the core network equipment of the second communication system, namely the UE moves from the first communication system to the second communication system based on the PDN connection supporting the movement to the second communication system, thereby avoiding the problem of prolonging the processing time in the moving process because the PDN gateway is not reachable in the moving process.

Further, the registration accept message sent by the core network device of the second communication system to the UE may include second PDU session status information, where the second PDU session status information is used to indicate a PDU session used by the UE in the second communication system. The PDU session indicated by the second PDU session status information belongs to the subset of the PDU session indicated by the first PDU session status information, that is, after the UE moves to the second communication system, the PDU session corresponding to the PDN connection supporting the move to the second communication system may be used.

The core network device of the second communication system may obtain the session status information of the second PDU through the following two different methods, where the two methods are different: in the first method, a core network device of a second communication system acquires context information of all PDN connections on the UE from a core network device of a first communication system (e.g., an MME in 4G); in the second method, the core network device of the second communication system obtains only context information supporting the PDN connection moved to the second communication system on the UE from the core network device of the first communication system (for example, an MME in 4G), which is described in detail below.

The first method is that when a core network device of a second communication system receives a registration message, the core network device of the second communication system acquires context information of all PDN connections on UE from the core network device of the first communication system, and determines to support PDN connection moving to the second communication system according to the context information and first PDU session state information contained in the registration message. Further, the core network device of the second communication system may further obtain an address of a PDN gateway corresponding to the PDN connection that supports moving to the second communication system, and a session identifier of a PDU session corresponding to the PDN connection. Then, the core network device of the second communication system may further obtain a session identifier supporting that the PDN gateway corresponding to the PDN connection moved to the second communication system sends the PDU session corresponding thereto.

Optionally, when the core network device of the second communication system determines to support the PDN connection moved to the second communication system, the core network device may obtain identifiers of all PDN connections according to the context information, map the identifier of each PDN connection to a session identifier of the PDU session, and when the session identifier of the PDU session obtained by mapping is in the PDU session indicated by the first PDU session state information, determine that the PDN connection supports the movement to the second communication system.

Further, when the registration acceptance message includes the second PDU session status information, the UE may further delete other PDN connections than the PDN connection corresponding to the PDU session indicated by the second PDU session status information, that is, delete context information of the PDN connection that is not transferred to the second communication system among all PDN connections of the UE, and the PDN connection that is not transferred to the second communication system may include a PDN connection that does not support moving to the second communication system and a PDN connection that supports moving to the second communication system but does not establish a corresponding PDU session in the second communication system. For example, due to insufficient resources on the RAN side or the gateway side, some PDU sessions are not established successfully, and the PDN connection corresponding to the PDU sessions that are not established successfully needs to be deleted.

Taking the 4G and 5G communication systems shown in fig. 1 as examples, the core network device of the second communication system may be an AMF, the core network device of the first communication system may be an MME, and the PDN gateway may be an SMF + PGW-C, and the UE may move to the second communication system through the flow shown in fig. 5. The method specifically comprises the following steps: s501, the UE determines that the UE needs to move from 4G to 5G, obtains a session identification list supporting the PDU session corresponding to the PDN connection moving to 5G, and generates first PDU session state information by using the session identification list; s502, the UE sends a registration request to the AMF, wherein the registration request comprises session state information of a first PDU; s503, the AMF sends a Context (Context) request to the MME, wherein the Context request is used for acquiring Context information of all PDN connections on the UE; s504, the MME returns a context response containing the context information to the AMF; s505.AMF sends context Acknowledgement (ACK) to MME; s506, the AMF sends an Update Location Request (Update Location Request) to the UDM + HSS; s507, the UDM + HSS returns an update position response to the AMF; s508, the UDM + HSS sends a Cancel Location (Cancel Location) to the MME; s509.MME returns cancel location confirmation to UDM + HSS; s510, the AMF determines to support PDN connection moving to a second communication system according to the context information and the first PDU session state information; s511, the AMF sends an N11 message to the SMF + PGW-C, wherein the N11 message carries an identifier (ID (s)) of a PDU session corresponding to the PDN connection supporting the movement to 5G; s512, the SMF + PGW-C returns an N11 response to the AMF; s513, the AMF sends a registration acceptance message to the UE, wherein the registration acceptance message comprises the session state information of the second PDU; s514, the UE returns a registration completion message to the AMF; and S515, the UE can obtain the corresponding Identification (ID) of the PDN connection according to the second PDU session state information, and delete the context information of other PDN connections except the obtained ID of the PDN connection.

In the second method, when the core network device of the second communication system receives the registration message, the core network device of the second communication system obtains the context information only supporting the PDN connection moved to the second communication system from the core network device of the first communication system, and determines, according to the context information, the PDN connection supported to be moved to the second communication system. Specifically, the core network device of the second communication system may send a context request message to the core network device of the first communication system, and the core network device of the first communication system determines that the UE needs to move to the second communication system according to that a sender of the context request message belongs to the second communication system. Thereafter, the core network device of the first communication system may acquire the PDN connection supporting the move to the second communication system, and return context information supporting only the PDN connection moving to the second communication system to the core network device of the second communication system.

Optionally, the determining, by the core network device of the first communication system, that the sender of the context request belongs to the second communication system includes: the context request message includes second information, where the second information is used to indicate that the sender of the context request message belongs to the second communication system, so that the core network device of the first communication system may determine that the sender of the context request belongs to the second communication system according to the second information. Or, the context request message includes a Globally Unique Temporary UE Identity (GUTI) of the UE, and the core network device of the first communication system is mapped from the GUTI of the second communication system according to the GUTI of the UE, and it is determined that the sender of the context request message belongs to the second communication system.

In addition, the core network device of the first communication system may also initiate a session deletion procedure. For the PDN connection supporting the move to the second communication system, the deletion session request sent by the core network device of the first communication system does not carry an Operation Indication Flag (Operation Indication Flag). For the PDN connection which does not support moving to the second communication system, the operation indication mark is carried in the request for deleting the session sent by the core network equipment of the first communication system.

Taking the 4G and 5G communication systems shown in fig. 1 as examples, the core network device of the second communication system may be an AMF, the core network device of the first communication system may be an MME, and the PDN gateway may be an SMF + PGW-C, and the UE may move to the second communication system through the flow shown in fig. 6. The method specifically comprises the following steps: s601, the UE determines that the UE needs to move from 4G to 5G, acquires a session identification list supporting the PDU session corresponding to the PDN connection moving to 5G, and generates first PDU session state information by using the session identification list; s602, the UE sends a registration request to the AMF, wherein the registration request comprises session state information of a first PDU; s603, the AMF sends a Context (Context) request message to the MME, wherein the Context request message carries a 5G indication, and the 5G indication is used for indicating that a sender of the Context request message belongs to a 5G communication system; s604, the MME determines that the UE needs to move to a 5G communication system according to the 5G instruction, so that PDN connection supporting movement to 5G is obtained; s605. the MME returns a context response to the AMF, wherein the context response comprises context information supporting PDN connection moving to 5G; s606.AMF sends context Acknowledgement (ACK) to MME; s607.AMF sends Update Location Request (Update Location Request) to UDM + HSS; s608, the UDM + HSS returns an update location response to the AMF; s609, the UDM + HSS sends a Cancel Location (Cancel Location) message to the MME; s610.MME returns cancel position confirmation message to UDM + HSS; s611, the AMF sends an N11 message to the SMF + PGW-C, wherein the N11 message carries an identifier (ID (s)) of a PDU session corresponding to the PDN connection supporting the movement to 5G; s612, the SMF + PGW-C returns an N11 response to the AMF; s613, the AMF sends a registration acceptance message to the UE, wherein the registration acceptance message comprises second PDU session state information; s614, the UE returns a registration completion message to the AMF; s615, the UE can obtain the corresponding Identification (ID) of the PDN connection according to the second PDU session state information and delete the context information of other PDN connections except the obtained ID of the PDN connection; s616, the MME acquires the PDN connection which does not support moving to 5G; s617, the MME sends a session deletion request to the S-GW, wherein the session deletion request carries an operation indication mark; s618, the S-GW sends a request for deleting the session to the SMF + PGW-C due to the fact that the operation indication mark is carried; s619.MME obtains PDN connection supporting movement to 5G; and S620, the MME sends a session deletion request to the S-GW, wherein the session deletion request does not carry an operation indication mark. The MME-initiated delete session procedure in fig. 6 includes steps S616-S620, where steps S616-S618 are used to delete PDN connections that do not support moving to 5G, i.e. delete connections between MME and S-GW and between S-GW and SMF + PGW-C; S619-S620 are used to delete PDN connections supporting mobility to 5G, i.e. only the connection between MME and S-GW.

In the inter-communication-system moving method provided in the embodiment of the present application, the UE may support, according to at least one PDN connection established in the first communication system, the PDN connection moved to the second communication system to generate first PDU session state information, send a registration message including the first PDU session state information to a core network device of the second communication system, receive a registration acceptance message sent by the core network device of the second communication system, where the registration acceptance message includes a PDU session used for indicating that the UE is used in the second communication system, and thereby move the UE from the first communication system to the second communication system. The UE is determined based on the core network equipment of the second communication system, and the PDU session which can be used by the UE in the second communication system moves from the first communication system to the second communication system, so that the problem of prolonged processing in the moving process due to the fact that a PDN gateway is not reachable in the moving process is solved.

Fig. 7 is a flowchart of a method for moving between communication systems according to an embodiment of the present application, and referring to fig. 7, the method includes the following steps.

S701: the core network equipment of the first communication system determines that the UE needs to move to the second communication system.

When the UE is in a Connected state (Connected), the base station of the first communication system may actively send a handover request to the core network device of the first communication system, and when the core network device of the first communication system receives the handover request, the handover request is used to request that the UE is handed over to the second communication system, so that the core network device of the first communication system may determine that the UE needs to move to the second communication system. Specifically, the core network device of the first communication system may determine that the UE needs to move to the second communication system according to the identifier of the target base station belonging to the second communication system.

In addition, the first communication system may be a fourth generation (4G) communication system, the second communication system may be a fifth generation (5G) communication system, the core network device of the first communication system may be an MME, the base station of the first communication system may be an E-UTRAN, and the MME is taken as an example in fig. 7 for explanation.

S702: and the core network equipment of the first communication system sends the context information of the PDN connection supporting the movement to the second communication system on the UE to the core network equipment of the second communication system, wherein the context information of the PDN connection is used for the core network equipment of the second communication system to establish the PDU session corresponding to the PDN connection.

The core network device of the first communication system may determine, according to information that the PDN connection on the UE supports or does not support moving to the second communication system, that the PDN connection supports moving to the second communication system is stored in advance. Thereafter, the core network device of the first communication system may send context information supporting only the PDN connection moved to the second communication system to the core network device of the second communication system. Optionally, the core network device of the second communication system may be an AMF, and fig. 7 illustrates the AMF as an example.

Optionally, the information that the PDN connection of the UE previously stored in the core network device of the first communication system supports or does not support moving to the second communication system may be information that the UE stores when establishing the PDN connection, and when the core network device of the first communication system is an MME, the description in fig. 4 may be specifically referred to.

S703: and the core network equipment of the second communication system receives the context information of the PDN connection and establishes a PDU session corresponding to the PDN connection according to the context information of the PDN connection so as to realize that the UE moves from the first communication system to the second communication system.

When the core network device of the second communication system receives the context information of the PDN connection, the core network device of the second communication system may send the context information of the PDN connection to the PDN gateway (for example, core network device SMF + PGW-C combined between 4G and 5G) according to an address of the PDN gateway included in the context information of the PDN connection, thereby establishing a PDU session corresponding to the PDN connection. The address of the PDN gateway may be an IP address, or may be a Fully Qualified Domain Name (FQDN), which may also be referred to as a Fully Qualified Domain Name. The context information of the PDN connection sent by the core network device of the second communication system to the PDN gateway may be a context of the PDN connection sent by the MME, or a subset of the context of the PDN connection sent by the MME. For example, it may be the identity of the bearer that the PDN connection contains.

Then, after the PDU session corresponding to the PDN connection is established, the core network device of the first communication system may send a Handover Command to the base station of the first communication system, so that the base station sends the Handover Command (Handover Command) to the UE, and when the UE receives the Handover Command, the UE may move from the first communication system to the second communication system. Because the UE moves from the first communication system to the second communication system based on the PDN connection supporting the movement to the second communication system, the problem of prolonged processing time in the moving process due to the fact that the PDN gateway is unreachable in the moving process is solved.

Further, after the UE moves from the first communication system to the second communication system, the core network device of the first communication system may also initiate a deletion procedure for deleting the PDN connection that does not support moving to the second communication system on the UE.

Taking the 4G and 5G communication systems shown in fig. 1 as examples, the core network device of the second communication system may be an AMF, the core network device of the first communication system may be an MME, and the PDN gateway may be an SMF + PGW-C, and the UE may move to the second communication system through the flow shown in fig. 8. The method specifically comprises the following steps: s801.E-UTRAN sends a switching request to MME, wherein the switching request is used for requesting to switch the UE to 5G; s802.MME determines that the target system is 5G, namely determines that the UE needs to move to 5G, and only sends context information supporting PDN connection moving to 5G to AMF according to the stored information that the PDN connection on the UE supports network intercommunication; s803. the MME sends a forwarding migration Request (forwarded Relocation Request) to the AMF, wherein the Request contains information of PDN connection established by the UE in the 4G network, and the PDN connection information contains an IP address of a PDN gateway (such as SMF + PGW-C) used by the PDN connection; s804, the AMF obtains an IP address of a PDN gateway in the PDN connection context, and sends a PDU session switching request to the IP address, wherein the PDU session switching request contains the context information of the PDN connection; s805, sending a PDU session switching response message to the AMF by the SMF + PGW-C, wherein the PDU session switching response message contains context information of a 5G PDU session; s806. the AMF sends a Handover Request (Handover Request) to the 5G RAN (namely the 5G base station), wherein the Handover Request comprises PDU session information; S807.5G RAN sends a handover request Acknowledgement (ACK) to AMF; s808, the AMF sends a PDU session modification request to the SMF + PGW-C; s809, the SMF + PGW-C returns a PDU session modification response to the AMF; s810. the AMF sends a forwarding migration Response (Forward Relocation Response) to the MME; s811.MME sends Handover Command (Handover Command) to E-UTRAN; s812.E-UTRAN sends switching command to UE; s813.UE sends a Handover Complete message to 5G RAN; S814.5G RAN sends Handover notification (Handover Notify) to AMF; s815. the AMF sends a forwarding migration completion notice (Forward Relocation Complete Notification) to the MME; s816, the MME initiates a flow of deleting the PDN connection which does not support moving to 5G; and S817, the MME sends a forwarding migration completion Notification acknowledgement (Forward Relocation Complete Notification ACK) to the AMF.

In the inter-communication-system moving method provided in the embodiment of the present application, when it is determined that the UE needs to move to the second communication system, the core network device of the first communication system sends, to the core network device of the second communication system, context information that supports PDN connection moving to the second communication system on the UE, where the context information of the PDN connection is used for the core network device of the second communication system to establish a PDU session corresponding to the PDN connection, and then, the core network device of the first communication system sends a handover command to the UE, so that the UE moves from the first communication system to the second communication system. Because the UE moves from the first communication system to the second communication system based on the PDU session corresponding to the PDN connection supporting the movement to the second communication system, the problem of prolonged processing in the moving process due to the unreachable PDN gateway in the moving process is avoided.

Fig. 9 is a flowchart of a method for moving between communication systems according to an embodiment of the present application, and referring to fig. 9, the method includes the following steps.

S901: and the first core network equipment of the second communication system acquires the address of a PDN gateway corresponding to the PDN connection of the UE in the first communication system.

The PDN connection established by the UE in the first communication system may include one or more PDN connections, and the first core network device may acquire an address of a PDN gateway corresponding to each PDN connection. The address of the PDN gateway may be an IP address of the PDN gateway, or may be a Fully Qualified Domain Name (FQDN), which may also be referred to as a full Name.

Specifically, the first core network device may receive context information of a PDN connection established in the first communication system by the UE, where the context information is sent by the core network device in the first communication system, where the established PDN connection may be one or more PDN connections, and the context information includes addresses of PDN gateways corresponding to all PDN connections, so that the first core network device may obtain the address of the PDN gateway corresponding to each PDN connection from the context information.

For example, the first communication system may be a 4G communication system, the second communication system may be a 5G communication system, the first core network device may be an AMF, the PDN connection corresponding PDN gateway may be a core network device SMF + PGW-C combined with 4G and 5G, the core network device in the first communication system is an MME, and the MME, the AMF, and the SMF + PGW-C are illustrated in fig. 9.

S902: the first core network device sends first information to a second core network device of the second communication system, wherein the first information comprises an address of the PDN gateway.

And the second core network equipment is used for judging whether the address of the PDN gateway is reachable for the first core network equipment. For example, the second core Network device may be a Network storage Function (NRF) in the 5G communication system, and the NRF is illustrated in fig. 9 as an example.

Specifically, before the first core network device sends the first information to the second core network device of the second communication system, the first core network device may first determine whether the address of the PDN gateway is reachable, and when the first core network device determines that the address of the PDN gateway is not reachable, the first core network device may send the first information including the address of the PDN gateway to the second core network device. The determining, by the first core network device, that the address of the PDN gateway is not reachable may include: and the first core network equipment determines that the address of the PDN gateway is not reachable according to the stored information, or the first core network equipment cannot determine whether the address of the PDN gateway is reachable.

Further, the first core Network device may further determine whether the UE is in a roaming state according to the address of the PDN gateway, and when it is determined that the UE is in the roaming state, the first core Network device may send the first information to the second core Network device when determining that the address of the PDN gateway is not reachable, where the first information may further include a data Network name DNN and a Public Land Mobile Network (PLMN) identifier. That is, when the first core network device determines that the UE is in the roaming state and the address of the PDN gateway is not reachable, the first information sent to the second core network device includes the following information: the address of the PDN gateway, the DNN and the PLMN identity.

S903: and when the second core network equipment receives the first information, the second core network equipment sends second information to the first core network equipment, wherein the second information is used for indicating whether the address of the PDN gateway is reachable.

When the second core network device receives the first information, the second core network device may determine whether the address of the PDN gateway is reachable, and send the determination result to the first core network device through the second information, where the second information is used to indicate whether the address of the PDN gateway is reachable. When the second core network device determines that the address of the PDN gateway is reachable, S904 is executed; otherwise, the UE cannot move from the first communication system to the second communication system, and the process ends.

Optionally, when the second core network device determines that the address of the PDN gateway is reachable, the second information may include first indication information, where the first indication information is used to indicate that the address of the PDN gateway is reachable; when the second core network device determines that the address of the PDN gateway is not reachable, the second information may include second indication information, where the second indication information is used to indicate that the address of the PDN gateway is not reachable.

Further, when the second core network device determines that the address of the PDN gateway is reachable and the UE is in the roaming state, the second information sent by the second core network device to the first core network device may further include an address of a v-SMF, where the v-SMF is a session management network element when the UE is in the roaming state.

S904: and when the first core network equipment determines that the address of the PDN gateway is reachable, the first core network equipment sends the context information of the PDN connection to the PDN gateway, wherein the context information of the PDN connection is used for the PDN gateway to establish the PDU session corresponding to the PDN connection in the second communication system.

S905: and the PDN gateway receives the context information of the PDN connection and establishes a PDU session corresponding to the PDN connection according to the context information of the PDN connection so as to enable the UE to move from the first communication system to the second communication information.

When the first core network device receives the second information and determines that the address of the PDN gateway is reachable according to the second information, the first core network device may send context information of the PDN connection to the PDN gateway, and after the PDN gateway receives the context information, may establish a PDU session corresponding to the PDN connection based on the context information. The UE may move from the first communication system to the second communication system after establishing the PDU session corresponding to the PDN connection.

Further, after the first core network device sends the context information of the PDN connection to the PDN gateway, and the PDN gateway establishes a PDU session corresponding to the PDN connection according to the context information of the PDN connection, the PDN gateway may send, to the first core network device, an identifier set of an EPS bearer included in the PDN connection. Correspondingly, the first core network device receives an Identification Set (EBIs) of the EPS bearer included in the PDN connection, generates EPS bearer establishment information according to the identification set of the EPS bearer, and sends the EPS bearer establishment information to the core network device of the first communication system, where the EPS bearer establishment information is used by the core network device of the first communication system to determine the EPS bearer successfully switched by the UE. The EPS Bearer establishment information may be an EPS Bearer establishment List (EPS Bearer Setup List), and when the core network device of the first communication system receives the EPS Bearer establishment List, the core network device may determine an EPS Bearer successfully switched by the UE.

For example, when the UE is in a Connected state (Connected), taking the 4G and 5G communication systems shown in fig. 1 as an example, the first core network device may be an AMF, the second core network device may be an NRF, and the PDN gateway may be an SMF + PGW-C, and a flow of moving the UE from the first communication system to the second communication system may be as shown in fig. 10 in conjunction with the method shown in fig. 9. The method specifically comprises the following steps: s1001.E-UTRAN sends switching request to MME, the switching request is used for requesting to switch the UE to 5G; s1002, the MME sends a forwarding migration Request (forwarded Relocation Request) to the AMF, wherein the Request contains information of PDN connection established by the UE in the 4G network, and the PDN connection information contains an IP address of a PDN gateway (such as SMF + PGW-C) used by the PDN connection; s1003.AMF obtains the IP address of PDN gateway in the PDN connection context, judges whether the IP address is accessible, and whether UE is in roaming state (if not, S1004 is executed, if it is accessible, S1006 is executed); s1004. the amf sends an NF discovery request to the NRF (carrying DNN and PLMN when it is determined in S1003 that it is not reachable and the UE is in roaming state); s1005.NRF returns NF discovery response to AMF (when UE is in roaming state, it carries v-SMF address); s1006, the AMF obtains an IP address of a PDN gateway in the PDN connection context, and sends a PDU session switching request to the IP address, wherein the PDU session switching request contains the context information of the PDN connection; s1007, SMF + PGW-C sends PDU conversation switch response message to AMF, the PDU conversation switch response message contains context information of 5G PDU conversation; s1008, the AMF sends a switching request to the 5G RAN (namely the 5G base station), wherein the switching request comprises PDU session information; S1009.5G the RAN sends a handover request acknowledgement to the AMF; s1010, the AMF sends a PDU session modification request to the SMF + PGW-C; s1011, if the SMF + PGW-C judges that the UE needs to move from 4G to 5G, a PDU session modification response is returned to the AMF, and the response carries an EPS Bearer Identification Set (EBIs) of PDN connection corresponding to the PDU session; s1012, after the AMF collects messages returned by all SMF + PGW-C, an EPS bearing establishment list is generated; s1013, the AMF sends a forwarding migration response containing the EPS bearing establishment list to the MME; s1014, the MME sends a handover command to the E-UTRAN; s1015.E-UTRAN sends switching command to UE; s1016, UE sends switching completion message to 5G RAN; S1017.5G the RAN sends a handover notification to the AMF; s1018. the AMF sends a forwarding migration completion notification to the MME; and S1019. the MME sends a notification confirmation of the completion of the forwarding migration to the AMF.

For example, when the UE is in an Idle state (Idle), taking the 4G and 5G communication systems shown in fig. 1 as an example, the first core network device may be an AMF, the second core network device may be an NRF, and the PDN gateway may be an SMF + PGW-C, and a flow of moving the UE from the first communication system to the second communication system may be as shown in fig. 11 in conjunction with the method shown in fig. 9. The method specifically comprises the following steps: s1101, the UE determines that the UE needs to move from 4G to 5G, acquires a session identification list supporting the PDU session corresponding to the PDN connection moving to 5G, and generates first PDU session state information by using the session identification list; s1102, the UE sends a registration request to an AMF, wherein the registration request comprises session state information of a first PDU; s1103. the AMF sends a context request to the MME, and the context request is used for acquiring context information of all PDN connections on the UE; s1104.MME returns context response containing the context information to AMF; s1105, the AMF sends context confirmation to the MME; s1106.AMF sends update position request to UDM + HSS; s1107. the UDM + HSS returns an update location response to the AMF; s1108, the UDM + HSS sends a cancel position to the MME; s1109.MME returns cancel position confirmation to UDM + HSS; s1110, the AMF acquires the IP address of the PDN gateway in the context information of the PDN connection, and judges whether the IP address is reachable and whether the UE is in a roaming state (if the IP address is not reachable, the step S1111 is executed, and if the IP address is reachable, the step S1113 is executed); s1111. the amf sends an NF discovery request to the NRF (carrying the DNN and the PLMN when it is determined in step S1110 that it is not reachable and the UE is in roaming state); s1112.nrf returns NF discovery response to AMF (carrying v-SMF address when the UE is in roaming state); s1113, the AMF sends an N11 message to the SMF + PGW-C, wherein the N11 message carries an identifier (ID (s)) of a PDU session corresponding to the PDN connection supporting the movement to 5G; s1114, SMF + PGW-C returns an N11 response to AMF; S1115.AMF sends a registration acceptance message to the UE, wherein the registration acceptance message contains second PDU session state information; s1116, the UE returns a registration completion message to the AMF; and S1117, the UE can obtain the corresponding Identification (ID) of the PDN connection according to the second PDU session state information, and delete the context information of other PDN connections except the obtained ID of the PDN connection.

It should be noted that, the first PDU session status information, the second PDU session status information, and the PDN connection supporting move to 5G in the foregoing embodiments are consistent with the explanation in the embodiment of fig. 5, and refer to the description in the embodiment of fig. 5 specifically, which is not described herein again in this embodiment of the present application.

In the inter-communication-system moving method provided in the embodiment of the present application, after acquiring an address of a PDN gateway corresponding to a PDN connection of the UE in a first communication system, a first core network device sends context information of the PDN connection to the PDN gateway only when it is determined that the address of the PDN gateway is reachable, so that the PDN gateway establishes a PDU session corresponding to the PDN connection in a second communication system, so that the UE moves from the first communication system to the second communication system, thereby avoiding a problem of extension during processing in a moving process due to unreachable PDN gateway in the moving process.

The above-mentioned scheme provided by the embodiment of the present application is introduced mainly from the perspective of interaction between network elements. It is to be understood that each network element, for example, the user equipment, the core network device of the first communication system, the core network device of the second communication system, and the like, includes a hardware structure and/or a software module corresponding to each function for implementing the functions. Those of skill in the art would readily appreciate that the present application is capable of being implemented as hardware or a combination of hardware and computer software for performing the exemplary network elements and algorithm steps described in connection with the embodiments disclosed herein. Whether a function is performed as hardware or computer software drives 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.

In the embodiment of the present application, according to the above method example, the user equipment, the core network device of the first communication system, and the core network device of the second communication system may be divided into the functional modules, for example, each functional module may be divided corresponding to each function, or two or more functions may be integrated into one processing module. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode. It should be noted that, in the embodiment of the present application, the division of the module is schematic, and is only one logic function division, and there may be another division manner in actual implementation.

In the case of adopting the functional modules divided corresponding to the respective functions, fig. 12 shows a possible structural schematic diagram of the user equipment in the foregoing embodiment, where the user equipment includes: a processing unit 1201, a transmitting unit 1202, and a receiving unit 1203. Wherein the processing unit 1201, the sending unit 1202 and the receiving unit 1203 are configured to support the user equipment to execute S301 in fig. 3; the processing unit 1201 is further configured to support the user equipment to perform S302 in fig. 3; the sending unit 1202 is further configured to support the user equipment to perform S303 in fig. 3; the receiving unit 1203 is further configured to support the user equipment to perform S304 in fig. 3. All relevant contents of each step related to the above method embodiment may be referred to the functional description of the corresponding functional module, and are not described herein again.

In a hardware implementation, the processing unit 1201 may be a processor; the transmitting unit 1202 may be a transmitter, the receiving unit 1203 may be a receiver, and the transmitter and the receiver may constitute a communication interface.

Fig. 13 is a schematic diagram illustrating a possible logical structure of the user equipment according to the foregoing embodiments, provided in this application. The user equipment includes: processor 1302, communication interface 1303, memory 1301, and bus 1304. The processor 1302, the communication interface 1303, and the memory 1301 are connected to each other via a bus 1304. In an embodiment of the present application, the processor 1302 is configured to control and manage actions of the user equipment, for example, the processor 1302 is configured to support the user equipment to perform S301 and S302 in fig. 3, and/or other processes for the techniques described herein. The communication interface 1303 is used for supporting the user equipment to perform communication. A memory 1301 for storing program codes and data of the user equipment.

The processor 1302 may be, among other things, a central processing unit, a general purpose processor, a digital signal processor, an application specific integrated circuit, a field programmable gate array or other programmable logic device, transistor logic, a hardware component, or any combination thereof. Which may implement or perform the various illustrative logical blocks, modules, and circuits described in connection with the disclosure. The processor may also be a combination of computing functions, e.g., comprising one or more microprocessors, a digital signal processor and a microprocessor, or the like. The bus 1304 may be a Peripheral Component Interconnect (PCI) bus, an Extended Industry Standard Architecture (EISA) bus, or the like. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, only one thick line is shown in FIG. 13, but this is not intended to represent only one bus or type of bus.

In the case of dividing the functional modules according to the respective functions, fig. 14 shows a possible structural diagram of the core network device of the first communication system in the above embodiment, for example, the core network device may be an MME in a 4G network. The core network device of the first communication system includes: a processing unit 1401, a transmitting unit 1402, and a receiving unit 1403. Wherein, the processing unit 1401 is configured to support the core network device to execute S701 in fig. 7; the sending unit 1402 is configured to support the core network device to execute S702 in fig. 7; processing unit 1401, transmitting unit 1402, and receiving unit 1403 are used to support the core network device to perform S703 in fig. 7, and/or other processes for the techniques described herein. All relevant contents of each step related to the above method embodiment may be referred to the functional description of the corresponding functional module, and are not described herein again.

In a hardware implementation, the processing unit 1401 may be a processor, the transmitting unit 1402 may be a transmitter, the receiving unit 1403 may be a receiver, and the receiver and the transmitter may form a communication interface.

Fig. 15 is a schematic diagram illustrating a possible logical structure of a core network device of the first communication system according to the foregoing embodiments provided in the present application, for example, the core network device may be an MME in a 4G network. The core network device of the first communication system includes: a processor 1502, a communication interface 1503, a memory 1501, and a bus 1504. The processor 1502, the communication interface 1503, and the memory 1501 are connected to each other by a bus 1504. In an embodiment of the application, the processor 1502 is configured to control and manage actions of the core network device, for example, the processor 1502 is configured to support the core network device to execute S701 in fig. 7, and/or other processes for the techniques described herein. Communication interface 1503 is used to support the core network device for communication. A memory 1501 is used for storing program codes and data of the core network device.

The processor 1502 may be, among other things, a central processing unit, a general purpose processor, a digital signal processor, an application specific integrated circuit, a field programmable gate array or other programmable logic device, transistor logic, a hardware component, or any combination thereof. Which may implement or perform the various illustrative logical blocks, modules, and circuits described in connection with the disclosure. The processor may also be a combination of computing functions, e.g., comprising one or more microprocessors, a digital signal processor and a microprocessor, or the like. The bus 1504 may be a peripheral component interconnect standard PCI bus or an extended industry standard architecture EISA bus, or the like. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, only one thick line is shown in FIG. 15, but this is not intended to represent only one bus or type of bus.

In the case of dividing the functional modules according to the respective functions, fig. 16 shows a schematic diagram of a possible structure of the core network device of the second communication system in the above embodiment, for example, the core network device may be an AMF in a 5G network. The core network device of the second communication system includes: an acquiring unit 1601, a transmitting unit 1602, and a processing unit 1603. The obtaining unit 1601 is configured to support the core network device to execute S901 in fig. 9, and support the core network device to receive the second information sent by S903 in fig. 9; the sending unit 1602 is configured to support the core network device to perform S902 and S904 in fig. 9; the obtaining unit 1601, the sending unit 1602, and the processing unit 1603 are used to support the core network device to perform S905 in fig. 9, and/or other processes for the techniques described herein. All relevant contents of each step related to the above method embodiment may be referred to the functional description of the corresponding functional module, and are not described herein again.

In a hardware implementation, the processing unit 1603 may be a processor; the obtaining unit 1601 may be a receiver, the sending unit 1603 may be a sender, and the receiver may constitute a communication interface.

Fig. 17 is a schematic diagram illustrating a possible logical structure of a core network device of the second communication system according to the foregoing embodiments provided in the present application, for example, the core network device may be an AMF in a 5G network. The core network device of the second communication system includes: a processor 1702, a communication interface 1703, a memory 1701, and a bus 1704. The processor 1702, communication interface 1703, and memory 1701 are interconnected by a bus 1704. In an embodiment of the application, the processor 1702 is configured to control and manage the actions of the core network device, for example, the processor 1702 is configured to support the core network device to execute S905 in fig. 9, and/or other processes for the techniques described herein. The communication interface 1703 is used to support the core network device to perform communication. A memory 1701 for storing program codes and data for the core network device.

The processor 1702 may be, among other things, a central processing unit, a general purpose processor, a digital signal processor, an application specific integrated circuit, a field programmable gate array or other programmable logic device, transistor logic, a hardware component, or any combination thereof. Which may implement or perform the various illustrative logical blocks, modules, and circuits described in connection with the disclosure. The processor may also be a combination of computing functions, e.g., comprising one or more microprocessors, a digital signal processor and a microprocessor, or the like. Bus 1704 may be a peripheral component interconnect standard PCI bus or an extended industry standard architecture EISA bus or the like. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, only one thick line is shown in FIG. 17, but this does not mean only one bus or one type of bus.

In another embodiment of the present application, a readable storage medium is further provided, where the readable storage medium includes a plurality of instructions to enable a device (which may be a single chip microcomputer, a chip, or the like) or a processor to execute all or part of the steps of the method according to each embodiment of the present invention, and specifically, may execute the steps of any device in the method for moving between communication systems provided in any diagram of fig. 3 to fig. 11. And the aforementioned readable storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.

There is also provided in another aspect of the present application a computer program product comprising computer executable instructions stored in a computer readable storage medium; the computer-executable instructions may be read by at least one processor of the device from a computer-readable storage medium, and the computer-executable instructions executed by the at least one processor may cause the device to perform all or part of the steps of the method according to the embodiments of the present invention, and in particular, may perform the steps of any device in the inter-communication system movement method provided in any of fig. 3-11.

In another embodiment of the present application, there is also provided a system, including a user equipment, a core network device of a first communication system, and a core network device of a second communication system; wherein the ue is the ue provided in fig. 2, fig. 12 or fig. 13; and/or the core network device of the first communication system is the core network device provided in fig. 14 or fig. 15; and/or the core network device of the second communication system is the core network device provided in fig. 16 or fig. 17.

In the system provided in the embodiment of the present application, the UE may move from the first communication system to the second communication system based on a PDU session corresponding to a PDN connection supporting the movement to the second communication system, or move from the first communication system to the second communication system after determining that an address of a PDN gateway corresponding to the PDN connection of the UE is reachable, thereby avoiding a problem of processing time extension in the moving process due to unreachable PDN gateways during the moving process of the UE.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.

Claims

1.A method for inter-communication system mobility, the method comprising:

user Equipment (UE) establishes at least one PDN connection in a first communication system;

the UE generates first PDU session state information, wherein the first PDU session state information is used for indicating that the at least one PDN connection supports a PDU session corresponding to a PDN connection moved to a second communication system, and the first communication system and the second communication system are communication systems of different generations;

the UE sends a registration message to core network equipment of the second communication system, wherein the registration message comprises the session state information of the first PDU;

and the UE receives a registration acceptance message sent by the core network equipment of the second communication system.

2. The method of claim 1, wherein the UE establishes at least one PDN connection within a first communication system, comprising:

the UE sends a first message to core network equipment of a first communication system, wherein the first message is used for establishing PDN connection in the first communication system by the UE;

the UE receives first information, wherein the first information is used for the UE to determine that the PDN connection supports or does not support moving to the second communication system.

3. The method of claim 2, further comprising:

and the UE distributes a PDU session identifier in the process of establishing the PDN connection and sends the PDU session identifier to a PDN gateway corresponding to the PDN connection.

4. The method of claim 2, wherein the UE generates first PDU session status information, comprising:

and the UE uses the identifier of the PDU session corresponding to the PDN connection supporting the movement to the second communication system to generate the first PDU session state information.

5. The method according to any one of claims 2 to 4,

the first information comprises first indication information for indicating that the PDN connection of the UE supports moving to the second communication system, the method further comprising: the UE determines that the PDN connection supports moving to the second communication system according to the first indication information; alternatively, the first and second electrodes may be,

the first information comprises second indication information for indicating that the PDN connection of the UE does not support moving to the second communication system, the method further comprising: and the UE determines that the PDN connection does not support moving to the second communication system according to the second indication information.

6. The method of claim 5, wherein the first information comprises session information for a PDU session corresponding to the PDN connection, and wherein the session information comprises at least one of: a session AMBR, QoS rules, SSC pattern or PDU session identification, the method further comprising:

and the UE determines that the PDN connection supports moving to the second communication system according to the session information.

7. Method according to any of claims 2-6, wherein said first information is included in a protocol configuration option, PCO.

8. The method according to any of claims 1-7, wherein before the UE generates the first PDU session state information, the method further comprises:

the UE determines that a move from the first communication system to the second communication system is required.

9. The method according to any of claims 1-8, wherein the registration accept message includes second PDU session status information indicating a PDU session used by the UE in the second communication system, the method further comprising:

and the UE deletes other PDN connections except the PDN connection corresponding to the PDU session indicated by the second PDU session state information.

10. The method according to any of claims 1-9, wherein the first communication system is a fourth generation 4G communication system and the second communication system is a fifth generation 5G communication system.

11. The method according to any of claims 1-10, wherein the first PDU session status information comprises: and indicating that the PDU session identification is respectively a value corresponding to 0-15, the PDU session identification corresponding to the PDN connection supporting the movement to the second communication system is 1, and other corresponding values are 0.

12.A method for inter-communication system mobility, the method comprising:

the method comprises the steps that first core network equipment receives context information of PDN connection established in a first communication system by User Equipment (UE), wherein the context information of the PDN connection is sent by the core network equipment in the first communication system;

the first core network equipment sends the context information of the PDN connection to a PDN gateway corresponding to the PDN connection, wherein the context information of the PDN connection is used for the PDN gateway to establish a PDU session corresponding to the PDN connection in a second communication system so as to realize that the UE moves from the first communication system to the second communication system;

the first core network equipment receives an identification set of EPS (evolved packet system) load contained in the PDN connection sent by a PDN gateway corresponding to the PDN connection;

and the first core network equipment generates an EPS bearer establishment list according to the identification set of the EPS bearer, and sends the EPS bearer establishment list to the core network equipment of the first communication system, wherein the EPS bearer establishment list is used for the core network equipment of the first communication system to determine that the UE is successfully switched to the EPS bearer of the second communication system.

13. The method of claim 12, wherein the first core network device sends context information of the PDN connection to a PDN gateway corresponding to the PDN connection, and further comprising:

the first core network equipment sends first information to second core network equipment of the second communication system, wherein the first information comprises an address of the PDN gateway;

and the first core network equipment receives second information sent by the second core network equipment, and sends context information of the PDN connection to the PDN gateway according to the second information.

14. The method according to claim 12 or 13, characterized in that the method further comprises:

and the first core network equipment acquires the address of the PDN gateway corresponding to the PDN connection according to the context information of the PDN connection.

15. The method of any one of claims 12-14, wherein sending, by the first core network device, the context information of the PDN connection to a PDN gateway corresponding to the PDN connection comprises:

the first core network equipment sends context information corresponding to PDN connection to a plurality of PDN gateways corresponding to the PDN connection;

the receiving, by the first core network device, an identifier set of an EPS bearer included in the PDN connection sent by a PDN gateway corresponding to the PDN connection includes:

the first core network equipment receives an identification set of EPS (evolved packet System) bearers included in a plurality of PDN connections sent by a plurality of PDN gateways;

the first core network device generates an EPS bearer establishment list according to the identification set of the EPS bearer, including:

and the first core network equipment generates the EPS bearing establishment list according to the identification set of EPS bearings included by the PDN connections.

16. The method of any of claims 12-15, wherein the first communication system and the second communication system are different generation communication systems.

17. The method according to any of claims 12-16, wherein the first communication system is a fourth generation 4G communication system and the second communication system is a fifth generation 5G communication system.

18.A user equipment, characterized in that the user equipment comprises a memory, a processor, a communication interface and a bus, the memory storing code and data therein, the processor, the memory and the communication interface being connected through the bus, the processor running the code in the memory to cause the user equipment to perform the inter-communication system mobility method according to any one of claims 1-11.

19. A core network device, characterized in that the core network device, as a first core network device, comprises a memory, a processor, a communication interface and a bus, the memory stores code and data, the processor, the memory and the communication interface are connected through the bus, and the processor runs the code in the memory to make the first core network device execute the inter-communication system mobility method according to any one of claims 12 to 17.

20. A chip system, characterized in that the chip system comprises a memory, a processor, a communication interface and a bus, the memory stores code and data therein, the processor, the memory and the communication interface are connected through the bus, the processor executes the code in the memory to cause the chip system to execute the inter-communication system moving method according to any one of claims 1 to 11 or the inter-communication system moving method according to any one of claims 12 to 17.

21. A readable storage medium having stored therein instructions which, when run on an apparatus, cause the apparatus to perform the inter-communication system mobility method of any one of claims 1-11.

22. A readable storage medium having stored therein instructions which, when run on an apparatus, cause the apparatus to perform the inter-communication system mobility method of any one of claims 12-17.