CN110049519B

CN110049519B - Session establishing method, session transferring method, device and storage medium

Info

Publication number: CN110049519B
Application number: CN201810036898.6A
Authority: CN
Inventors: 金辉; 欧阳国威; 杨皓睿; 段小嫣; 窦凤辉; 李小娟
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2018-01-15
Filing date: 2018-01-15
Publication date: 2021-08-13
Anticipated expiration: 2038-01-15
Also published as: CN110049519A

Abstract

The application provides a session establishing method, a session transferring method, a device and a storage medium, wherein the session transferring method comprises the following steps: in the process of PDU session establishment in the 5G communication system, the UE sends priority information indicating the priority of transferring the PDU session requested to be established by the UE to the 4G communication system to the AMF, when the PDU session of the UE needs to be transferred to the 4G communication system subsequently, the AMF determines which PDU session is transferred to the 4G communication system according to the priority information of each PDU session, and the subsequent session transfer process is carried out, PDN connection establishment is completed in the 4G communication system, and the purpose of selectively transferring the PDU session can be achieved in the process of moving the UE from the 5G communication system to the 4G communication system.

Description

Session establishing method, session transferring method, device and storage medium

Technical Field

The present application relates to communications technologies, and in particular, to a session establishing method, a session transferring method, a device, and a storage medium.

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. For example, the UE can move from a fifth Generation (5G) communication network to a fourth Generation (4G) communication network, and the 5G communication network is an extension of the 4G communication network, and has the characteristics of high performance, low delay, high capacity, and the like, and the highest data transmission speed can reach tens of Gbps or more.

When the UE moves from the 5G communication network to the 4G communication network, how to transfer the PDU session of the UE in the 5G communication network to the 4G communication network to establish the PDN connection becomes an urgent problem to be solved.

Disclosure of Invention

The application provides a session establishing method, a session transferring method, equipment and a storage medium, which are used for realizing that UE establishes a PDU session in a 5G communication network and realizing that the PDU session of the UE in the 5G communication network is transferred to a 4G communication network to establish PDN connection.

In a first aspect, the present application provides a session establishment method, including:

UE sends a first message to access and AMF, wherein the first message is used for establishing PDU session; the first message comprises a PDU session establishment request and priority information, wherein the priority information is used for indicating the priority of transferring the PDU session which is requested to be established by the UE to a 4G communication system;

and the UE receives the AMF and sends a second message, wherein the second message comprises PDU session establishment acceptance.

Optionally, the method further includes:

the UE determines the priority information according to a combination of one or more of the following:

the PDU session corresponds to S-NSSAI;

an application using the PDU session;

URSP saved by the UE;

and the UE requests the QoS parameters of the QoS flow corresponding to the default QoS rule of the established PDU session.

Optionally, the second message further includes:

priority information of the PDU session determined by a network.

Optionally, the UE stores the priority information of the PDU session determined by the network.

Optionally, the method further includes:

and when the UE moves from the 5G communication system to the 4G communication system, the UE determines a first PDU session transferred to the 4G communication system according to the priority information of each PDU session corresponding to the used DNN.

Optionally, the determining, by the UE, a first PDU session to be transferred to the 4G communication system according to the priority information of each PDU session corresponding to the used DNN, includes:

and the UE determines the PDU session with the highest priority as the first PDU session transferred to the 4G communication system according to the priority information corresponding to each PDU session corresponding to the DNN.

In a second aspect, the present application provides a session transfer method, including:

when UE moves from a 5G communication system to a 4G communication system, AMF sends information of PDN connection corresponding to a first PDU session to MME, wherein the information of PDN connection is used for the MME to establish PDN connection for the UE;

the first PDU session is a PDU session with the highest priority transferred to a 4G communication system in a plurality of PDU sessions established by the UE and using the first DNN.

Optionally, the method further includes:

in the process of establishing the first PDU session, the AMF receives priority information sent by the UE; or,

the AMF receives priority information of the first PDU session sent by a first SMF + PGW-C;

wherein the priority information is used for indicating the priority of the first PDU session transfer to the 4G communication system.

Optionally, the receiving, by the AMF, the priority information of the first PDU session sent by the first SMF + PGW-C includes:

in an EBI allocation process, the AMF receives priority information of the first PDU session sent by the first SMF + PGW-C.

Optionally, in an EBI allocation process, the receiving, by the AMF, the priority information of the first PDU session sent by the first SMF + PGW-C includes:

the AMF receives an EBI allocation request sent by the first SMF + PGW-C;

if the AMF determines that EBI is already allocated to a second PDU session corresponding to the first DNN, and a second SMF + PGW-C corresponding to the second PDU session is different from the first SMF + PGW-C, judging whether the priority of the first PDU session is higher than that of the second PDU session;

if the priority of the first PDU session is higher than that of the second PDU session, the AMF allocates EBI for the first PDU session;

or,

the AMF receives an EBI allocation request sent by the first SMF + PGW-C;

if the AMF determines that EBI is already allocated to the third PDU session corresponding to the first DNN and the third PDU session corresponds to the first SMF + PGW-C, the AMF allocates EBI to the first PDU session;

or,

the AMF receives an EBI allocation request sent by the first SMF + PGW-C;

if the AMF determines that the first DNN corresponds to a second SMF + PGW-C, and the priority level corresponding to the first SMF + PGW-C is higher than that corresponding to the second SMF + PGW-C, the AMF allocates an EBI for the first PDU session;

or,

the AMF receives an EBI allocation request sent by the first SMF + PGW-C;

and if the AMF determines that the first DNN corresponds to a first SMF + PGW-C, the AMF allocates an EBI for the first PDU session.

Optionally, the EBI allocation request includes an identifier of the first PDU session, and the method includes:

and the AMF determines a first DNN corresponding to the first PDU session according to the identifier of the first PDU session.

Optionally, the method further includes:

the AMF determines the priority corresponding to the first SMF + PGW-C and the priority corresponding to the second SMF + PGW-C according to the saved S-NSSAI priority corresponding to the SMF + PGW-C;

or,

and the AMF acquires the corresponding priority of each SMF + PGW-C.

Optionally, the method further includes:

and the AMF sends information of PDN connection corresponding to a fourth PDU session to the MME, wherein the fourth PDU session and the first PDU session use the same DNN and SMF + PGW-C.

Optionally, the method further includes:

the AMF acquires the first PDU session with the highest priority in a plurality of PDU sessions corresponding to the first DNN;

the AMF requests information of the PDN connection corresponding to the first PDU session to a first SMF + PGW-C corresponding to the first PDU session;

or,

and the AMF requests information of the PDN connection corresponding to the first PDU session from a first SMF + PGW-C corresponding to the first PDU session, and acquires information of PDN connections corresponding to other PDU sessions using the first DNN.

the AMF receives an allocation retention priority ARP corresponding to a default quality of service rule corresponding to the first PDU session sent by the first SMF + PGW-C, or,

the AMF receives the priority of the S-NSSAI corresponding to the first PDU session sent by the first SMF + PGW-C, or,

and the AMF receives and stores the priority provided by the UE and sent by the first SMF + PGW-C.

Optionally, the priority information received by the AMF and sent by the UE includes:

the priority of the S-NSSAI corresponding to the PDU session; or,

the priority of S-NSSAI and DNN corresponding to the PDU session; or,

a priority of an application using the PDU session.

In a third aspect, the present application provides a session establishment method, including:

the method comprises the steps that in the process of establishing a PDU session of UE, the SMF + PGW-C obtains priority information of the PDU session of the UE transferred to a 4G communication system;

and the SMF + PGW-C sends the priority information to the UDM + HSS or the AMF.

Optionally, the priority information is a priority of the received PDU session sent by the UE being transferred to a 4G communication system;

or,

the priority information is the priority of the PDU session transfer to the 4G communication system determined by the SMF + PGW-C according to the S-NSSAI of the PDU session;

or,

and the priority information is the priority of transferring the PDU session to the 4G communication system, which is determined by the SMF + PGW-C according to the S-NSSAI and the DNN of the PDU session.

In a fourth aspect, the present application provides a session transfer method, including:

the UDM + HSS stores the corresponding relation between the addresses and the priorities of DNN, SMF + PGW-C used by the PDU session of the UE; the priority is used for indicating the priority of transferring the PDU session corresponding to the SMF + PGW-C to the 4G communication system, or the priority is used for indicating the priority of transferring the SMF + PGW-C to the 4G communication system;

the UDM + HSS determines a first SMF + PGW-C address used by the UE in the 4G communication system according to the stored priority;

the UDM + HSS sends the first SMF + PGW-C address and the APN to an MME; wherein the APN corresponds to the DNN.

Optionally, the determining, according to the priority, a first SMF + PGW-C address used by the UE in the 4G communication system includes:

and the UDM + HSS determines the address of the SMF + PGW-C with the highest priority in all the SMF + PGW-Cs corresponding to the DNN as the first SMF + PGW-C address.

Optionally, the method further includes:

the UDM + HSS receives DNN, SMF + PGW-C addresses and priorities sent by SMF + PGW-C;

the UDM + HSS determines whether the corresponding relation between the other SMF + PGW-C corresponding to the DNN and the priority is stored or not;

if so, the UDM + HSS judges whether the priority corresponding to the SMF + PGW-C is higher than the priority corresponding to the other stored SMF + PGW-C corresponding to the DNN;

and if so, the UDM + HSS stores the corresponding relation between the SMF + PGW-C and the priority. In a specific implementation, the correspondence between the SMF + PGW-C and the priority may be represented by the correspondence between the SMF + PGW-C address and the priority.

Optionally, the correspondence between DNN, SMF + PGW-C and priority includes:

corresponding relation among APN corresponding to DNN, SMF + PGW-C and priority; or,

corresponding relation of DNN, S-NSSAI, SMF + PGW-C and priority; or,

corresponding relation among APN corresponding to DNN, S-NSSAI, SMF + PGW-C and priority; or,

and the PDU session identification, the SMF + PGW-C and the priority.

In a fifth aspect, the present application provides a session transfer method, including:

the PDU session of the UE stored by the UDM + HSS is transferred to the corresponding relation between the address and the priority of the APN used in the 4G communication system, the address of the SMF + PGW-C and the priority; the priority is used for indicating the priority of transferring the PDU session corresponding to the SMF + PGW-C to the 4G communication system, or the priority is used for indicating the priority of transferring the SMF + PGW-C to the 4G communication system;

and the UDM + HSS sends the first SMF + PGW-C address and the APN corresponding to the first SMF + PGW-C address to an MME.

Optionally, the determining, by the UDM + HSS, the first SMF + PGW-C address used by the UE in the 4G communication system according to the stored priority includes:

and the UDM + HSS determines the address of the SMF + PGW-C with the highest priority in the stored SMF + PGW-C as the address of the first SMF + PGW-C according to the corresponding relation.

Optionally, the method further includes:

the UDM + HSS receives the APN, the SMF + PGW-C address and the priority sent by the SMF + PGW-C;

the UDM + HSS determines whether the corresponding relation between other SMF + PGW-C corresponding to the DNN corresponding to the APN and the priority is locally stored;

and if so, the UDM + HSS stores the corresponding relation between the SMF + PGW-C and the priority.

Optionally, the correspondence between the APN, the SMF + PGW-C, and the priority includes:

corresponding relation of DNN, S-NSSAI, SMF + PGW-C and priority; or,

and the PDU session identification, the SMF + PGW-C and the priority.

In a sixth aspect, the present application provides a session transfer method, including:

when UE determines to transfer a first PDU session to a 4G communication system, the UE acquires a first APN corresponding to the first PDU session;

the UE sends a PDN connection establishment request to an MME; the PDN connection establishment request carries the first APN corresponding to the first PDU session;

and the UE receives PDN connection establishment acceptance sent by the MME so as to establish the PDN connection.

Optionally, the acquiring, by the UE, a first APN corresponding to the first PDU session includes:

and the UE acquires the first APN corresponding to the first PDU session according to the stored corresponding relation between the PDU session and the APN.

Optionally, the correspondence between the PDU session and the APN includes:

selecting auxiliary information S-NSSAI of a single network slice of the PDU session and a corresponding relation between DNN and APN;

or,

and the PDU session identification of the PDU session corresponds to the APN.

Optionally, the method further includes:

in the process of establishing the first PDU session, the UE receives a first APN which is sent by the SMF + PGW-C and corresponds to the first PDU session;

and the UE acquires and stores the corresponding relation between the first PDU session and the first APN.

the UE determines the first APN corresponding to S-NSSAI and DNN of the first PDU according to a UE routing strategy URSP;

or,

the UE generates the first APN corresponding to S-NSSAI and DNN of the first PDU.

Optionally, the method further includes:

and the UE receives a first APN-AMBR which is sent by the SMF + PGW-C and corresponds to the first PDU session.

In a seventh aspect, the present application provides a session establishing method, including:

receiving a PDU session establishment request sent by UE by SMF + PGW-C;

the SMF + PGW-C acquires an APN corresponding to the PDU session requested to be established by the UE;

the SMF + PGW-C sends the APN and the address of the SMF + PGW-C to a UDM + HSS;

and the SMF + PGW-C sends PDU session establishment acceptance to the UE, and completes the establishment process of the PDU session.

Optionally, the PDU session establishment request includes S-NSSAI and DNN, and the SMF + PGW-C acquires an APN corresponding to the PDU session requested to be established by the UE, including:

and the SMF + PGW-C acquires APNs corresponding to the S-NSSAI and the DNN.

Optionally, the acquiring, by the SMF + PGW-C, the APN corresponding to the S-NSSAI and the DNN includes:

and the SMF + PGW-C acquires the APN corresponding to the S-NSSAI and the DNN according to the stored strategy information.

Or,

and the SMF + PGW-C acquires the APN corresponding to the S-NSSAI and the DNN according to the stored corresponding relation between the S-NSSAI and the DNN and the APN.

Optionally, the PDU session establishment request includes the APN, and the SMF + PGW-C acquires the APN corresponding to the PDU session requested to be established by the UE, including:

and the SMF + PGW-C acquires the APN from the PDU session establishment request.

Optionally, the PDU session establishment accept includes the APN.

Optionally, the method further includes:

and the SMF + PGW-C acquires APN-AMBR corresponding to the APN.

Optionally, the method further includes:

the SMF + PGW-C sends the APN-AMBR corresponding to the APN to the UE;

and/or the presence of a gas in the gas,

and the SMF + PGW-C sends the APN-AMBR corresponding to the APN to the UDM + HSS.

Optionally, the acquiring, by the SMF + PGW-C, an APN-AMBR corresponding to the APN includes:

the SMF + PGW-C acquires APN-AMBR corresponding to the APN according to the session AMBR of the UE;

or,

and the SMF + PGW-C acquires the APN-AMBR corresponding to the APN according to the subscription information of the UE.

Optionally, the acquiring, by the SMF + PGW-C, the APN-AMBR corresponding to the APN according to the session AMBR of the UE in the current network includes:

and the SMF + PGW-C adds session AMBRs of all PDU sessions using DNN corresponding to the APN to obtain the APN-AMBR.

Optionally, the method further includes:

and the SMF + PGW-C sends first information to the UDM + HSS, wherein the first information is used for the UDM + HSS to determine the APN-AMBR corresponding to the APN.

Optionally, the first information includes:

the APN-AMBR which is determined by the SMF + PGW-C and corresponds to the APN;

or,

DNN corresponding to the PDU session;

or,

and the APN corresponding to the DNN corresponding to the PDU session.

In an eighth aspect, the present application provides a session transfer method, including:

when UE determines that a PDU session needs to be moved from 5G to 4G, the UE sends a PDN connection request to MME; the PDN connection request carries the APN corresponding to the PDU session and a PDU session identifier;

and the UE receives a PDN connection response returned by the MME.

Optionally, the PDN connection request further carries a transfer indication; the transfer indication is used for indicating the transfer of the PDU session to the 4G communication system.

In a ninth aspect, the present application provides a session transfer method, including:

MME receives a PDN connection request sent by UE; the PDN connection request carries the APN corresponding to the PDU session and a PDU session identifier;

the MME determines the first SMF + PGW-C according to the APN and PDU session identification corresponding to the PDU session and the corresponding relation among the APN, the SMF + PGW-C and the PDU session identification obtained from the UDM + HSS;

the MME sends a session creation request to the first SMF + PGW-C;

the MME receives a session creation response returned by the first SMF + PGW-C;

and the MME returns a PDN connection response to the UE according to the session creation response.

Optionally, the method further includes:

and the MME receives the corresponding relation among the APN, the SMF + PGW-C and the PDU session identification sent by the UDM + HSS.

In a tenth aspect, the present application provides a session transfer method, including:

MME receives a PDN connection request sent by UE; the PDN connection request carries a transfer instruction, an APN corresponding to the PDU session and a PDU session identifier, wherein the transfer instruction is used for instructing the PDU session to be transferred to a 4G network;

the MME selects a first SMF + PGW-C from at least one SMF + PGW-C corresponding to the APN according to the APN corresponding to the PDU session;

the MME sends a session creation request to the first SMF + PGW-C;

if the MME receives a response of session creation rejection returned by the first SMF + PGW-C; and the created session rejection response carries the rejected reason, the MME selects any one second SMF + PGW-C except the first SMF + PGW-C from at least one SMF + PGW-C corresponding to the APN to initiate session creation, and repeats the step until the session creation is completed, and the MME returns a PDN connection response to the UE.

In an eleventh aspect, the present application provides a session transfer method, further comprising:

the method comprises the steps that an SMF + PGW-C receives a session creating request sent by an MME, wherein the session creating request carries a transfer indication, a PDU session identifier and an APN;

the SMF + PGW-C detects whether a PDU session corresponding to the PDU session identifier exists according to the PDU session identifier;

if not, returning a created session rejection response to the MME, wherein the created session rejection response indicates the reason of rejection;

and if so, completing session creation according to the session creation request, and sending a session creation response to the MME.

In each of the above implementations, it should be understood that the SMF + PGW-C address includes an identification of SMF + PGW-C, or alternatively, a Fully Qualified Domain Name (FQDN) of SMF + PGW-C, or alternatively, an IP address of SMF + PGW-C.

In a twelfth aspect, the present application provides a UE, comprising:

a sending module, configured to send a first message to an access and an AMF, where the first message is used to establish a PDU session; the first message comprises a PDU session establishment request and priority information, wherein the priority information is used for indicating the priority of transferring the PDU session which is requested to be established by the UE to a 4G communication system;

the receiving module is used for receiving a second message sent by the AMF, wherein the second message comprises a PDU session establishment acceptance.

Optionally, the UE further includes:

a processing module for determining the priority information from a combination of one or more of:

the PDU session corresponds to S-NSSAI;

an application using the PDU session;

URSP saved by the UE;

Optionally, the second message further includes: priority information of the PDU session determined by a network.

Optionally, the UE further includes: and the processing module is used for determining a first PDU session transferred to the 4G communication system according to the priority information of each PDU session corresponding to the used DNN when the UE moves from the 5G communication system to the 4G communication system.

Optionally, the processing module is specifically configured to:

and determining the PDU session with the highest priority as the first PDU session transferred to the 4G communication system according to the priority information corresponding to each PDU session corresponding to the DNN.

In a thirteenth aspect, the present application provides an AMF comprising:

a sending module, configured to send, to an MME, information of a PDN connection corresponding to a first PDU session when a UE moves from a 5G communication system to a 4G communication system, where the information of the PDN connection is used for the MME to establish a PDN connection for the UE;

Optionally, the AMF further includes: a receiving module to:

receiving priority information sent by the UE in the first PDU session establishment process; or,

receiving priority information of the first PDU session sent by a first SMF + PGW-C;

Optionally, the receiving module is specifically configured to:

and in the EBI allocation process, receiving the priority information of the first PDU session sent by the first SMF + PGW-C.

Optionally, the AMF further includes: a processing module;

the receiving module is further configured to receive an EBI allocation request sent by the first SMF + PGW-C;

the processing module is specifically configured to:

if it is determined that the EBI is already allocated to the second PDU session corresponding to the first DNN, and the second SMF + PGW-C corresponding to the second PDU session is different from the first SMF + PGW-C, determining whether the priority of the first PDU session is higher than the priority of the second PDU session;

if the priority of the first PDU session is higher than that of the second PDU session, the EBI is distributed for the first PDU session;

or,

the processing module is specifically configured to:

if it is determined that an EBI has been allocated to the third PDU session corresponding to the first DNN and the third PDU session corresponds to the first SMF + PGW-C, allocating an EBI to the first PDU session;

or,

the processing module is specifically configured to:

if the fact that the first DNN corresponds to a second SMF + PGW-C is locally stored is determined, and the priority level corresponding to the first SMF + PGW-C is higher than the priority level corresponding to the second SMF + PGW-C, EBI is distributed for the first PDU session;

or,

the processing module is specifically configured to:

and if the first DNN is determined to correspond to the first SMF + PGW-C, allocating an EBI for the first PDU session.

Optionally, the EBI allocation request includes an identifier of the first PDU session, and the processing module is further configured to determine a first DNN corresponding to the first PDU session according to the identifier of the first PDU session.

Optionally, the processing module is further configured to:

the priority of the S-NSSAI corresponding to the SMF + PGW-C is stored, and the priority corresponding to the first SMF + PGW-C and the priority corresponding to the second SMF + PGW-C are determined;

or,

and acquiring the corresponding priority of each SMF + PGW-C.

Optionally, the sending module is further configured to send, to the MME, information of a PDN connection corresponding to a fourth PDU session, where the fourth PDU session and the first PDU session use the same DNN and SMF + PGW-C.

Optionally, the AMF further includes: a processing module;

the processing module is configured to obtain the first PDU session with the highest priority among the PDU sessions corresponding to the first DNN;

the sending module is further configured to request, to a first SMF + PGW-C corresponding to the first PDU session, information of the PDN connection corresponding to the first PDU session;

or,

the sending module is further configured to request, to a first SMF + PGW-C corresponding to the first PDU session, information of the PDN connection corresponding to the first PDU session, and acquire information of PDN connections corresponding to other PDU sessions using the first DNN.

Optionally, the receiving module is specifically configured to:

receiving an allocation retention priority ARP corresponding to a default quality of service rule corresponding to the first PDU session sent by the first SMF + PGW-C, or,

receiving the priority of the S-NSSAI corresponding to the first PDU session sent by the first SMF + PGW-C, or,

and receiving and storing the priority provided by the UE and sent by the first SMF + PGW-C.

Optionally, the priority information sent by the UE and received by the receiving module includes:

the priority of the S-NSSAI corresponding to the PDU session; or,

the priority of S-NSSAI and DNN corresponding to the PDU session; or,

a priority of an application using the PDU session.

In a fourteenth aspect, the present application provides an SMF + PGW-C, comprising:

the processing module is used for acquiring priority information of the PDU session transfer of the UE to the 4G communication system in the PDU session establishment process of the UE;

and the sending module is used for sending the priority information to the UDM + HSS or the AMF.

Optionally, the SMF + PGW-C further includes: a receiving module;

the priority information is the priority of transferring the PDU session sent by the UE to a 4G communication system and received by the receiving module;

or,

the priority information is the priority of transferring the PDU session to a 4G communication system, which is determined by the processing module according to the S-NSSAI of the PDU session;

or,

the priority information is the priority of transferring the PDU session to the 4G communication system, which is determined by the processing module according to the S-NSSAI and the DNN of the PDU session.

In a fifteenth aspect, the present application provides a UDM + HSS, comprising:

the storage module is used for storing the corresponding relation between the addresses and the priorities of DNN, SMF + PGW-C used by the PDU session of the UE; the priority is used for indicating the priority of transferring the PDU session corresponding to the SMF + PGW-C to the 4G communication system, or the priority is used for indicating the priority of transferring the SMF + PGW-C to the 4G communication system;

the processing module is used for determining a first SMF + PGW-C address used by the UE in the 4G communication system without the stored priority;

a sending module, configured to send the first SMF + PGW-C address and APN to an MME; wherein the APN corresponds to the DNN.

Optionally, the processing module is specifically configured to:

and determining the address of the SMF + PGW-C with the highest priority in all the SMF + PGW-Cs corresponding to the DNN as the first SMF + PGW-C address.

Optionally, the UDM + HSS further comprises: a receiving module;

the receiving module is used for receiving the DNN, the SMF + PGW-C address and the priority sent by the SMF + PGW-C;

the processing module is further configured to determine whether correspondence between other SMF + PGW-C corresponding to the DNN and the priority is saved;

if so, the processing module is further configured to determine whether the priority corresponding to the SMF + PGW-C is higher than the priority corresponding to the other saved SMF + PGW-C corresponding to the DNN;

if yes, the storage module stores the corresponding relation between the SMF + PGW-C and the priority.

Optionally, the correspondence between DNN, SMF + PGW-C and priority includes:

corresponding relation of DNN, S-NSSAI, SMF + PGW-C and priority; or,

and the PDU session identification, the SMF + PGW-C and the priority.

In a sixteenth aspect, the present application provides a UDM + HSS, comprising:

the storage module is used for storing the corresponding relation between the addresses and the priorities of the APN used in the PDU session transfer of the UE to the 4G communication system, the SMF + PGW-C; the priority is used for indicating the priority of transferring the PDU session corresponding to the SMF + PGW-C to the 4G communication system, or the priority is used for indicating the priority of transferring the SMF + PGW-C to the 4G communication system;

the processing module is used for determining a first SMF + PGW-C address used by the UE in the 4G communication system according to the stored priority;

a sending module, configured to send the first SMF + PGW-C address and an APN corresponding to the first SMF + PGW-C address to an MME.

Optionally, the processing module is specifically configured to determine, according to the correspondence, an address of an SMF + PGW-C with a highest priority in the stored SMF + PGW-cs as the first SMF + PGW-C address.

Optionally, the UDM + HSS further includes:

the receiving module is used for receiving the APN, the SMF + PGW-C address and the priority sent by the SMF + PGW-C;

the processing module is configured to determine whether correspondence between other SMF + PGW-C corresponding to the DNN corresponding to the APN and the priority is locally stored;

corresponding relation of DNN, S-NSSAI, SMF + PGW-C and priority; or,

and the PDU session identification, the SMF + PGW-C and the priority.

In a seventeenth aspect, the present application provides a UE, comprising:

the processing module is used for acquiring a first APN corresponding to a first PDU session when the first PDU session is determined to be transferred to a 4G communication system;

a sending module, configured to send a PDN connection establishment request to an MME; the PDN connection establishment request carries the first APN corresponding to the first PDU session;

and the receiving module is used for receiving PDN connection establishment acceptance sent by the MME so as to establish the PDN connection.

Optionally, the processing module is specifically configured to:

and acquiring the first APN corresponding to the first PDU session according to the stored corresponding relation between the PDU session and the APN.

Optionally, the correspondence between the PDU session and the APN includes:

or,

and the PDU session identification of the PDU session corresponds to the APN.

Optionally, the receiving module is further configured to receive a first APN, which is sent by the SMF + PGW-C and corresponds to the first PDU session, in the process of establishing the first PDU session;

the processing module is further configured to acquire and store, in a storage device, a correspondence between the first PDU session and the first APN.

Optionally, the processing module is specifically configured to:

determining the first APN corresponding to S-NSSAI and DNN of the first PDU according to URSP;

or,

generating the first APN corresponding to the S-NSSAI and DNN of the first PDU.

Optionally, the receiving module is further configured to receive a first APN-AMBR, which is sent by the SMF + PGW-C and corresponds to the first PDU session.

In an eighteenth aspect, the present application provides an SMF + PGW-C, comprising:

a receiving module, configured to receive a PDU session establishment request sent by a UE;

the processing module is used for acquiring APN corresponding to the PDU session requested to be established by the UE;

a sending module, configured to send the APN and the address of SMF + PGW-C to UDM + HSS;

the sending module is further configured to send a PDU session establishment acceptance to the UE, and complete the PDU session establishment process.

Optionally, the PDU session establishment request includes S-NSSAI and DNN, and the processing module is specifically configured to:

and acquiring APNs corresponding to the S-NSSAI and the DNN.

Optionally, the processing module is specifically configured to:

and acquiring the APN corresponding to the S-NSSAI and the DNN according to the stored strategy information.

Or,

and acquiring the APN corresponding to the S-NSSAI and the DNN according to the stored corresponding relation between the S-NSSAI and the DNN and the APN.

Optionally, the PDU session establishment request includes the APN, and the processing module is further configured to obtain the APN from the PDU session establishment request.

Optionally, the PDU session establishment accept includes the APN.

Optionally, the processing module is further configured to acquire an APN-AMBR corresponding to the APN.

Optionally, the sending module is further configured to:

sending the APN-AMBR corresponding to the APN to the UE;

and/or the presence of a gas in the gas,

and sending the APN-AMBR corresponding to the APN to the UDM + HSS.

Optionally, the processing module is specifically configured to:

acquiring APN-AMBR corresponding to the APN according to the session AMBR of the UE;

or,

and acquiring APN-AMBR corresponding to the APN according to the subscription information of the UE.

Optionally, the processing module is specifically configured to:

and adding session AMBRs of all PDU sessions using DNN corresponding to the APN to obtain the APN-AMBR.

Optionally, the sending module is further configured to send first information to a UDM + HSS, where the first information is used for the UDM + HSS to determine an APN-AMBR corresponding to the APN.

Optionally, the first information includes:

the APN-AMBR which is determined by the SMF + PGW-C and corresponds to the APN;

or,

DNN corresponding to the PDU session;

or,

and the APN corresponding to the DNN corresponding to the PDU session.

In a nineteenth aspect, the present application provides a UE, comprising:

a sending module, configured to send a PDN connection request to the MME when it is determined that the PDU session needs to be moved from 5G to 4G; the PDN connection request carries the APN corresponding to the PDU session and a PDU session identifier;

and the receiving module is used for receiving the PDN connection response returned by the MME.

In a twentieth aspect, the present application provides an MME, comprising:

a receiving module, configured to receive a PDN connection request sent by a UE; the PDN connection request carries the APN corresponding to the PDU session and a PDU session identifier;

the processing module is used for determining the first SMF + PGW-C according to the APN and the PDU session identifier corresponding to the PDU session and the corresponding relation among the APN, the SMF + PGW-C and the PDU session identifier obtained from the UDM + HSS;

a sending module, configured to send a session creation request to the first SMF + PGW-C;

the receiving module is further configured to receive a session creation response returned by the first SMF + PGW-C;

and the sending module is also used for returning a PDN connection response to the UE according to the session creating response.

Optionally, the receiving module is further configured to receive a correspondence between an APN, an SMF + PGW-C and a PDU session identifier sent by the UDM + HSS.

In a twenty-first aspect, the present application provides an MME, comprising:

a receiving module, configured to receive a PDN connection request sent by a UE; the PDN connection request carries a transfer instruction, an APN corresponding to the PDU session and a PDU session identifier, wherein the transfer instruction is used for instructing the PDU session to be transferred to a 4G network;

the processing module is used for selecting a first SMF + PGW-C from at least one SMF + PGW-C corresponding to the APN according to the APN corresponding to the PDU session;

if the receiving module receives a session creation rejection response returned by the first SMF + PGW-C; the created session rejection response carries the rejected reason, the processing module selects any one of second SMF + PGW-C except the first SMF + PGW-C from at least one SMF + PGW-C corresponding to the APN to initiate session creation, and repeats the step until the session creation is completed, and the MME returns a PDN connection response to the UE.

In a twenty-second aspect, the present application provides an SMF + PGW-C, comprising:

a receiving module, configured to receive a session creation request sent by an MME, where the session creation request carries a transfer indication, a PDU session identifier, and an APN;

the processing module is used for detecting whether the PDU session corresponding to the PDU session identifier exists according to the PDU session identifier;

a sending module, configured to return a create session rejection response to the MME if the processing module detects that the request is negative, where the create session rejection response indicates a reject reason;

the processing module is further used for completing a session creation according to the session creation request if the processing module is in the normal state;

the sending module is further configured to send a create session response to the MME.

In a twenty-third aspect, the present application provides a UE, comprising: a transmitter for transmitting a message, a receiver for receiving a message, a memory, and a processor.

In the specific implementation of the UE:

the transmitter is used for transmitting a first message to the access and AMF, and the first message is used for establishing a PDU session; the first message comprises a PDU session establishment request and priority information, wherein the priority information is used for indicating the priority of transferring the PDU session which is requested to be established by the UE to a 4G communication system;

the receiver is used for receiving the AMF and sending a second message, wherein the second message comprises PDU session establishment acceptance.

Optionally, the UE further includes:

a processor for determining the priority information from a combination of one or more of:

the PDU session corresponds to S-NSSAI;

an application using the PDU session;

URSP saved by the UE;

Optionally, the UE further includes: and the processor is used for determining a first PDU session transferred to the 4G communication system according to the priority information of each PDU session corresponding to the used DNN when the UE moves from the 5G communication system to the 4G communication system.

Optionally, the processor is specifically configured to:

In a twenty-fourth aspect, the present application provides an AMF comprising: a transmitter for transmitting a message, a receiver for receiving a message, a memory, and a processor.

In the specific implementation of the AMF:

a transmitter, configured to send, to an MME, information of a PDN connection corresponding to a first PDU session when a UE moves from a 5G communication system to a 4G communication system, where the information of the PDN connection is used for the MME to establish a PDN connection for the UE;

Optionally, the AMF further includes: a receiver for:

Optionally, the receiver is specifically configured to:

Optionally, the AMF further includes: a processor;

the receiver is further configured to receive an EBI allocation request sent by the first SMF + PGW-C;

the processor is specifically configured to:

or,

the processor is specifically configured to:

or,

the processor is specifically configured to:

or,

the processor is specifically configured to:

Optionally, the EBI allocation request includes an identifier of the first PDU session, and the processor is further configured to determine a first DNN corresponding to the first PDU session according to the identifier of the first PDU session.

Optionally, the processor is further configured to:

or,

and acquiring the corresponding priority of each SMF + PGW-C.

Optionally, the sender is further configured to send, to the MME, information of a PDN connection corresponding to a fourth PDU session, where the fourth PDU session and the first PDU session use the same DNN and SMF + PGW-C.

Optionally, the AMF further includes: a processor;

the processor is configured to obtain the first PDU session with a highest priority among a plurality of PDU sessions corresponding to the first DNN;

the sender is further configured to request, from a first SMF + PGW-C corresponding to the first PDU session, information of the PDN connection corresponding to the first PDU session;

or,

the sender is further configured to request, from a first SMF + PGW-C corresponding to the first PDU session, information of the PDN connection corresponding to the first PDU session, and acquire information of PDN connections corresponding to other PDU sessions using the first DNN.

Optionally, the receiver is specifically configured to:

Optionally, the priority information received by the receiver and sent by the UE includes:

the priority of the S-NSSAI corresponding to the PDU session; or,

the priority of S-NSSAI and DNN corresponding to the PDU session; or,

a priority of an application using the PDU session.

In a twenty-fifth aspect, the present application provides an SMF + PGW-C, comprising: a transmitter for transmitting a message, a receiver for receiving a message, a memory, and a processor.

The specific implementation of the SMF + PGW-C is as follows:

the processor is used for acquiring priority information of the PDU session transfer of the UE to the 4G communication system in the PDU session establishment process of the UE;

a transmitter for transmitting the priority information to the UDM + HSS or the AMF.

Optionally, the SMF + PGW-C further includes: a receiver;

the priority information is the priority of the PDU session transfer to the 4G communication system, which is received by the receiver and sent by the UE;

or,

the priority information is the priority of transferring the PDU session to a 4G communication system, which is determined by the processor according to the S-NSSAI of the PDU session;

or,

the priority information is the priority of transferring the PDU session to the 4G communication system, which is determined by the processor according to the S-NSSAI and the DNN of the PDU session.

In a twenty-sixth aspect, the present application provides a UDM + HSS, comprising: a transmitter for transmitting a message, a receiver for receiving a message, a memory, and a processor.

In the specific implementation of the UDM + HSS:

the memory is used for storing the corresponding relation between the addresses and the priorities of DNN, SMF + PGW-C used by the PDU session of the UE; the priority is used for indicating the priority of transferring the PDU session corresponding to the SMF + PGW-C to the 4G communication system, or the priority is used for indicating the priority of transferring the SMF + PGW-C to the 4G communication system;

the processor is used for determining a first SMF + PGW-C address used by the UE in the 4G communication system without the stored priority;

a transmitter, configured to send the first SMF + PGW-C address and APN to an MME; wherein the APN corresponds to the DNN.

Optionally, the processor is specifically configured to:

Optionally, the UDM + HSS further comprises: a receiver;

the receiver is used for receiving the DNN, the SMF + PGW-C address and the priority sent by the SMF + PGW-C;

the processor is further configured to determine whether correspondence between other SMF + PGW-C corresponding to the DNN and the priority is saved;

if so, the processor is further configured to determine whether the priority corresponding to the SMF + PGW-C is higher than the priority corresponding to the other saved SMF + PGW-C corresponding to the DNN;

and if so, the memory stores the corresponding relation between the SMF + PGW-C and the priority.

Optionally, the correspondence between DNN, SMF + PGW-C and priority includes:

corresponding relation of DNN, S-NSSAI, SMF + PGW-C and priority; or,

and the PDU session identification, the SMF + PGW-C and the priority.

In a twenty-seventh aspect, the present application provides a UDM + HSS, comprising: a transmitter for transmitting a message, a receiver for receiving a message, a memory, and a processor.

In the specific implementation of the UDM + HSS:

the memory is used for storing the corresponding relation between APN used in the PDU session transfer of the UE to the 4G communication system, the address of SMF + PGW-C and the priority; the priority is used for indicating the priority of transferring the PDU session corresponding to the SMF + PGW-C to the 4G communication system, or the priority is used for indicating the priority of transferring the SMF + PGW-C to the 4G communication system;

the processor is used for determining a first SMF + PGW-C address used by the UE in the 4G communication system according to the stored priority;

and the sender is used for sending the first SMF + PGW-C address and the APN corresponding to the first SMF + PGW-C address to an MME.

Optionally, the processor is specifically configured to determine, according to the correspondence, an address of an SMF + PGW-C with a highest priority in the stored SMF + PGW-cs as a first SMF + PGW-C address.

Optionally, the UDM + HSS further includes:

the receiver is used for receiving the APN, the SMF + PGW-C address and the priority sent by the SMF + PGW-C;

the processor is configured to determine whether correspondence between other SMF + PGW-C corresponding to the DNN corresponding to the APN and the priority is locally stored;

if so, the processor is further configured to determine whether the priority corresponding to the SMF + PGW-C is higher than the priority corresponding to the other SMF + PGW-C corresponding to the DNN that has been saved;

and if so, the corresponding relation between the SMF + PGW-C and the priority is stored in a memory.

corresponding relation of DNN, S-NSSAI, SMF + PGW-C and priority; or,

and the PDU session identification, the SMF + PGW-C and the priority.

In a twenty-eighth aspect, the present application provides a UE, comprising: a transmitter for transmitting a message, a receiver for receiving a message, a memory, and a processor.

In the specific implementation of the UE:

the processor is used for acquiring a first APN corresponding to a first PDU session when the first PDU session is determined to be transferred to a 4G communication system;

a transmitter, configured to send a PDN connection establishment request to an MME; the PDN connection establishment request carries the first APN corresponding to the first PDU session;

and the receiver is used for receiving the PDN connection establishment acceptance sent by the MME so as to establish the PDN connection.

Optionally, the processor is specifically configured to:

Optionally, the correspondence between the PDU session and the APN includes:

or,

and the PDU session identification of the PDU session corresponds to the APN.

Optionally, the receiver is further configured to receive a first APN, which is sent by the SMF + PGW-C and corresponds to the first PDU session, in the process of establishing the first PDU session;

the processor is further configured to acquire and store, in a storage device, a correspondence between the first PDU session and the first APN.

Optionally, the processor is specifically configured to:

determining the first APN corresponding to S-NSSAI and DNN of the first PDU according to a UE routing strategy URSP;

or,

generating the first APN corresponding to the S-NSSAI and DNN of the first PDU.

Optionally, the receiver is further configured to receive a first APN-AMBR, which is sent by the SMF + PGW-C and corresponds to the first PDU session.

In a twenty-ninth aspect, the present application provides an SMF + PGW-C, comprising: a transmitter for transmitting a message, a receiver for receiving a message, a memory, and a processor.

The specific implementation of the SMF + PGW-C is as follows:

the receiver is used for receiving a PDU session establishment request sent by the UE;

a processor, configured to acquire an APN corresponding to a PDU session requested to be established by the UE;

a sender, configured to send the APN and the address of the SMF + PGW-C to a UDM + HSS;

the sender is further configured to send a PDU session establishment acceptance to the UE, and complete the PDU session establishment procedure.

Optionally, the PDU session establishment request includes S-NSSAI and DNN, and the processor is specifically configured to:

and acquiring APNs corresponding to the S-NSSAI and the DNN.

Optionally, the processor is specifically configured to:

Or,

Optionally, the PDU session setup request includes the APN, and the processor is further configured to obtain the APN from the PDU session setup request.

Optionally, the PDU session establishment accept includes the APN.

Optionally, the processor is further configured to acquire an APN-AMBR corresponding to the APN.

Optionally, the transmitter is further configured to:

sending the APN-AMBR corresponding to the APN to the UE;

and/or the presence of a gas in the gas,

and sending the APN-AMBR corresponding to the APN to the UDM + HSS.

Optionally, the processor is specifically configured to:

or,

Optionally, the processor is specifically configured to:

Optionally, the sender is further configured to send first information to a UDM + HSS, where the first information is used for the UDM + HSS to determine an APN-AMBR corresponding to the APN.

Optionally, the first information includes:

the APN-AMBR which is determined by the SMF + PGW-C and corresponds to the APN;

or,

DNN corresponding to the PDU session;

or,

and the APN corresponding to the DNN corresponding to the PDU session.

In a thirtieth aspect, the present application provides a UE, comprising: a transmitter for transmitting a message, a receiver for receiving a message, a memory, and a processor.

In the specific implementation of the UE:

a transmitter for transmitting a PDN connection request to the MME when it is determined that the PDU session needs to be moved from 5G to 4G; the PDN connection request carries the APN corresponding to the PDU session and a PDU session identifier;

and the receiver is used for receiving the PDN connection response returned by the MME.

In a thirty-first aspect, the present application provides an MME, comprising: a transmitter for transmitting a message, a receiver for receiving a message, a memory, and a processor.

In the specific implementation of the MME:

the receiver is used for receiving a PDN connection request sent by the UE; the PDN connection request carries the APN corresponding to the PDU session and a PDU session identifier;

the processor is used for determining the first SMF + PGW-C according to the APN and the PDU session identifier corresponding to the PDU session and the corresponding relation among the APN, the SMF + PGW-C and the PDU session identifier obtained from the UDM + HSS;

a transmitter, configured to send a create session request to the first SMF + PGW-C;

the receiver is further configured to receive a create session response returned by the first SMF + PGW-C;

and the sender is also used for returning a PDN connection response to the UE according to the session creation response.

Optionally, the receiver is further configured to receive a correspondence between an APN, an SMF + PGW-C and a PDU session identifier sent by the UDM + HSS.

In a thirty-second aspect, the present application provides an MME, comprising: a transmitter for transmitting a message, a receiver for receiving a message, a memory, and a processor.

In the specific implementation of the MME:

the receiver is used for receiving a PDN connection request sent by the UE; the PDN connection request carries a transfer instruction, an APN corresponding to the PDU session and a PDU session identifier, wherein the transfer instruction is used for instructing the PDU session to be transferred to a 4G network;

the processor is used for selecting a first SMF + PGW-C from at least one SMF + PGW-C corresponding to the APN according to the APN corresponding to the PDU session;

if the receiver receives a session creation rejection response returned by the first SMF + PGW-C; the created session rejection response carries the rejected reason, the processor selects any second SMF + PGW-C except the first SMF + PGW-C from at least one SMF + PGW-C corresponding to the APN to initiate session creation, and repeats the step until the session creation is completed, and the MME returns a PDN connection response to the UE.

In a thirty-third aspect, the present application provides an SMF + PGW-C, comprising: a transmitter for transmitting a message, a receiver for receiving a message, a memory, and a processor.

The specific implementation of the SMF + PGW-C is as follows:

the receiver is used for receiving a session creation request sent by an MME, wherein the session creation request carries a transfer indication, a PDU session identifier and an APN;

the processor is used for detecting whether the PDU session corresponding to the PDU session identification exists or not according to the PDU session identification;

a sender, configured to return a create session rejection response to the MME if the processor detects that the MME is not present, where the create session rejection response indicates a reason for rejection;

the processor is further configured to complete a session creation according to the session creation request if the request is positive;

the transmitter is further configured to send a create session response to the MME.

In the above-mentioned specific implementation of the UE or each network device, the number of the processors is at least one, and the processors are used for executing execution instructions stored in the memory, that is, computer programs. Optionally, the memory may also be integrated within the processor.

In a thirty-fourth aspect, the present application provides a storage medium for storing a computer program for implementing the session establishment method provided in any one of the first aspect.

In a thirty-fifth aspect, the present application provides a storage medium for storing a computer program for implementing the session transfer method provided in any one of the second aspect.

In a sixteenth aspect, the present application provides a storage medium for storing a computer program for implementing the session establishment method provided in any one of the third aspect.

In a thirty-seventh aspect, the present application provides a storage medium for storing a computer program for implementing the session transfer method provided in any one of the fourth aspect.

In a thirty-eighth aspect, the present application provides a storage medium for storing a computer program for implementing the session transfer method provided in any one of the fifth aspects.

In a thirty-ninth aspect, the present application provides a storage medium for storing a computer program for implementing the session transfer method provided in any one of the sixth aspects.

Fortieth aspect, the present application provides a storage medium for storing a computer program for implementing the session establishment method provided in any one of the seventh aspects.

Fortieth aspect, the present application provides a storage medium for storing a computer program for implementing the session transfer method provided in any one of the eighth aspects.

Forty-second aspect, the present application provides a storage medium for storing a computer program for implementing the session transfer method provided in any one of the ninth aspects.

In a forty-third aspect, the present application provides a storage medium for storing a computer program for implementing the session transfer method provided in any one of the tenth aspect.

In a fourteenth aspect, the present application provides a storage medium for storing a computer program for implementing the session transfer method provided in any one of the eleventh aspects.

According to the session establishing method, the session transferring method, the equipment and the storage medium, the UE sends priority information indicating the priority level of the PDU session requested to be established by the UE to the AMF to transfer to the 4G communication system in the PDU session establishing process in the 5G communication system, when the PDU session of the UE needs to be transferred to the 4G communication system subsequently, the AMF determines which PDU session is transferred to the 4G communication system according to the priority level information of each PDU session, the subsequent session transferring process is carried out, and PDN connection establishment is completed in the 4G communication system. The purpose that the PDU session can be selectively transferred in the process that the UE moves from the 5G communication system to the 4G communication system is achieved.

Drawings

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

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

fig. 3 is a schematic flowchart of a session establishment method according to a first embodiment of the present application;

fig. 4 is a schematic flowchart of a session transfer method according to a first embodiment of the present application;

fig. 5 is a schematic flowchart of a first embodiment of a session establishment method with an N26 interface scenario according to the present application;

fig. 6 is a schematic flowchart of a first embodiment of a session transfer method without an N26 interface scenario according to an embodiment of the present application;

fig. 7 is a flowchart illustrating a second embodiment of a session establishment method according to an embodiment of the present application;

fig. 8 is a flowchart illustrating a third embodiment of a session establishment method according to an embodiment of the present application;

fig. 9 is a flowchart illustrating a second embodiment of a session transfer method according to an embodiment of the present application;

fig. 10 is a flowchart illustrating an example of a session establishment method and a session transfer method according to an embodiment of the present application;

fig. 11 is a flowchart illustrating another example of a session establishment method and a session transfer method according to an embodiment of the present application

Fig. 12 is a schematic flowchart of a third embodiment of a session transfer method according to an embodiment of the present application;

fig. 13 is a schematic flowchart of a fourth embodiment of a session transfer method according to an embodiment of the present application;

fig. 14 is a schematic flowchart of a fifth embodiment of a session transfer method according to an embodiment of the present application;

fig. 15 is a flowchart illustrating a further example of a session establishment method and a session transfer method according to an embodiment of the present application;

fig. 16 is a flowchart illustrating a further example of a session establishment method and a session transfer method according to an embodiment of the present application;

fig. 17 is a schematic structural diagram of a UE according to a first embodiment of the present application;

FIG. 18 is a schematic structural diagram of a first embodiment of an AMF according to an embodiment of the present application;

FIG. 19 is a schematic structural diagram of a first embodiment of an SMF + PGW-C provided in the present application;

fig. 20 is a schematic structural diagram of a UDM + HSS according to a first embodiment of the present application;

fig. 21 is a schematic structural diagram of a second embodiment of a UDM + HSS according to the present application;

fig. 22 is a schematic structural diagram of a second UE embodiment according to an embodiment of the present application;

fig. 23 is a schematic structural diagram of a second embodiment of an SMF + PGW-C provided in the present application;

fig. 24 is a schematic structural diagram of a UE according to a third embodiment of the present application;

fig. 25 is a schematic structural diagram of a first MME according to an embodiment of the present application;

fig. 26 is a schematic structural diagram of a second MME according to an embodiment of the present application;

fig. 27 is a schematic structural diagram of a third embodiment of an SMF + PGW-C provided in the present application;

fig. 28 is a schematic structural diagram of a UE according to a fourth embodiment of the present application;

fig. 29 is a schematic structural diagram of a second AMF embodiment according to an embodiment of the present application;

fig. 30 is a schematic structural diagram of a fourth embodiment of an SMF + PGW-C provided in the present application;

fig. 31 is a schematic structural diagram of a third embodiment of a UDM + HSS provided in the present application;

fig. 32 is a schematic structural diagram of a fourth embodiment of a UDM + HSS according to the present application;

fig. 33 is a schematic structural diagram of a UE according to a fifth embodiment of the present application;

FIG. 34 is a schematic structural diagram of a fifth embodiment of an SMF + PGW-C provided in the embodiments of the present application;

fig. 35 is a schematic structural diagram of a UE according to a sixth embodiment of the present application;

fig. 36 is a schematic structural diagram of a third MME according to an embodiment of the present application;

fig. 37 is a schematic structural diagram of a fourth MME according to an embodiment of the present application;

fig. 38 is a schematic structural diagram of a sixth embodiment of the SMF + PGW-C provided in the 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 a 4G communication System (also referred to as a 4G communication network or 4G), a set of Evolved Packet System (EPS) bearers (Bearer) established on the UE has the same IP address and Access Point Name (APN), and the EPS Bearer refers to a data transmission channel in the 4G communication System. At the UE and network side, a PDN connection is identified by an IP address and APN.

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

A Default (Default) EPS bearer refers to an EPS bearer established while establishing a PDN connection, and the Default EPS bearers are all bearers without Guaranteed Bit Rate (non GBR). A Dedicated (Dedicated) EPS bearer refers to a bearer that is established after a PDN connection is established in order to meet a certain Quality of Service (QoS) requirement. Wherein, one PDN connection may include multiple dedicated EPS bearers and one default EPS bearer. The dedicated EPS bearer may be a GBR EPS bearer or a Non GBR EPS bearer.

Protocol Data Unit (PDU) Session (Session): in a 5G communication system (also referred to as a 5G communication Network or 5G), a combination of a set of QoS flows (flows) established on a UE, the QoS flows having the same IP address and Data Network Name (DNN). The QoS flow refers to a data transmission channel within the 5G communication system. At the UE and network side, one PDU session is identified by an IP address and DNN.

The PDU session is in a deactivated state (deactivated), which may also be referred to as a PDU session being deactivated (deactivated) or a PDU session not being activated (not active), and means that the PDU session is established, but a User Plane (UP) connection of the PDU session does not exist, which may specifically be one or a combination of the following operations: 1. the UPF (User Plane Function) deletes or suspends information corresponding to the base station side in the N3 interface (for example, an IP address, a tunnel identifier, a port number, and the like of the base station, so that the UPF cannot be sent to the base station after downlink data arrives at the UPF). 2. The base station deletes or suspends a Radio resource corresponding to the PDU session (the Radio resource in this application may be a time-frequency resource for carrying Data corresponding to the PDU session, or a Data Radio Bearer (DRB) for carrying Data corresponding to the PDU session, or a combination thereof), and the base station deletes or suspends information on the UPF side in the N3 interface (for example, an IP address, a tunnel identifier, a port number, and the like of the UPF, so that uplink Data cannot be sent to the UPF after reaching the base station). 3. And the UE deletes or suspends the corresponding wireless resources according to the configuration of the base station. The N3 interface is the interface between UPF and base station

The PDU session is in an active state (active), which may also be referred to as activated, and means that the PDU session exists in a user plane connection between the UE and the UPF, and includes an air interface connection between the UE and the base station and a connection of an N3 interface between the base station and the UPF, and when uplink and downlink data arrive in the activated PDU session, the PDU session may be directly transmitted between the UE and the UPF.

PDU session context: including the IP address, DNN, SMF and UPF addresses used by the PDU session, and context information for each QoS flow. Wherein one PDU session may include a plurality of QoS flows. There is a QoS flow in the PDU session in the 5G communication system corresponding to the dedicated EPS bearer in the 4G communication system and there is a QoS flow corresponding to the default EPS bearer in the 4G communication system. Specifically, one dedicated EPS bearer may correspond to one or more QoS flows in a PDU session, and one default EPS bearer may also correspond to one or more QoS flows in a PDU session. Optionally, the default EPS bearer may correspond to a default QoS flow. The default QoS flow refers to a QoS flow corresponding to a default QoS rule (rule). Optionally, one dedicated GBR EPS bearer corresponds to one or more GBR QoS flows.

Fig. 1 is a system architecture diagram of a communication system according to an embodiment of the present application, and a system architecture of a communication system according to an embodiment of the present application is shown in fig. 1, where the system architecture includes a 5G communication system and a 4G communication system.

Referring to fig. 1, the communication system includes a UE, an Evolved UMTS Terrestrial Radio Access Network (E-UE ran), i.e. a 4G base station, 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 (SMF) + a Control Plane of a PDN Gateway (PDN Gateway-Control Plane, PGW-C), a Policy Control Function (Policy Control Function, PCF) + a Policy and Charging Rules Function unit (Policy and Charging Rules Function, PCRF), a Home subscription Server (PCRF, a universal Subscriber Server (HSS) and a Mobility Management Function (Data Access Function, Data Access Management Function), AMF) and 5G Radio Access Network (5G Radio 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 transfer of the UE context can be carried out 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 or the IP address is unchanged and the PGW-C is unchanged. In addition, the PDU session established by the UE in the 5G network can also be transferred to the 4G network, and the IP address of the UE is ensured to be unchanged. The UE moving between 4G and 5G includes 2 cases: the UE moves in a switching (handover) mode in a connected state; in an idle state, the UE moves by means of reselection (reselection or select).

It should be noted that the number of SMFs corresponding to the UE may be one or more, that is, multiple SMFs serve the UE simultaneously.

In a 4G communication system, in a scenario where a UE moves from a non-3GPP network to a 3GPP network, a specific solution of session connection is as follows:

when UE establishes PDN connection in the non-3GPP network, the non-3GPP network sends the corresponding relation between APN and PGW to HSS;

after the UE moves to the 3GPP network, the MME obtains, from the HSS, the correspondence between the APNs and PGWs of all non-3GPP PDN connections on the UE.

UE sends a PDN connection establishment request carrying a handover (handover) indication and an APN, MME sends a PDN connection establishment request carrying APN and handover indication to a PGW according to the APN and the corresponding relationship between the APN and the PGW obtained from HSS

The PGW selects one PDN connection from the multiple PDN connections corresponding to the APN for transfer according to the APN

In the scheme, the UE cannot determine the transfer sequence, and the aim of transferring all PDN connections is achieved by sending PDN connection establishment requests carrying handover indications and APNs for multiple times.

Based on the architecture shown in fig. 1, it is necessary to know that in the 5G communication system, the N26 interface is an optional interface. When the network has no N26 interface, the UE transfers the PDU session of 5G to 4G by a PDN connection establishment request carrying handover indication similar to 4G, and ensures IP continuity.

In the 5G communication system, a slice scene is introduced, and in the scene, in order to achieve the purpose of inter-slice isolation, each slice has an independent SMF + PGW-C. The Data Network Name (DNN) is a Name used in the 5G communication Network, and corresponds to the APN of 4G one by one. Multiple network slices may use the same DNN, and thus one DNN for a UE may correspond to multiple SMF + PGW-cs. Meanwhile, a new requirement is provided in 5G, and when the UE has multiple PDU sessions in 5G, the UE may choose to move part of PDU sessions to 4G. In the current 5G, the UE informs the SMF + PGW-C which PDU session is transferred to the 4G this time by sending a PDU session ID to the SMF + PGW-C through the PCO. Thereby achieving the purpose of UE selective transfer. The MME does not handle the contents within the PCO.

However, in the scenario without the N26 interface, when one DNN of the UE corresponds to multiple SMF + PGW-cs, the MME cannot determine which PDU session on the SMF + PGW-C the UE wants to transfer according to the APN provided by the UE and the correspondence between the APN and the SMF + PGW-C provided by the HSS, so that the purpose of selective transfer of the UE cannot be achieved.

The Aggregate Maximum Bit Rate (AMBR) is used to limit the Maximum transmission Rate of all non-Guaranteed Bit Rate (GBR) bearer bearers on the UE. The method is divided into APN-AMBR and UE-AMBR. The APN-AMBR is used to limit the maximum transmission rate that can be used by non-GBR bearers of all PDN connections of each APN on the UE, and is typically used in the UE and PGW. UE-AMBR is the maximum transmission rate that a non GBR bearer of all PDN connections (which may span multiple APNs) on the UE can use, typically UE-AMBR is used on the base station.

When UE establishes PDN connection in a 4G communication system, MME sends APN AMBR obtained from UE subscription to PGW, PGW determines APN AMBR which can be used by UE according to Policy Control and Charging (PCC) Policy, and sends the APN AMBR to MME for storage, and MME further sends the APN AMBR to UE.

And the MME adds APN AMBRs corresponding to a plurality of APNs in use on the UE to obtain a UE-AMBR, compares the UE-AMBR with the signed UE-AMBR of the UE, takes a small value as the UE-AMBR and sends the UE-AMBR to the base station.

However, when one DNN of the UE corresponds to multiple SMFs + PGW-cs, and the UE moves from the 5G communication system to the 4G communication system, there may be a case where one APN corresponds to multiple PGWs, which breaks through the specification that one APN specified by the 4G can only correspond to one PGW, and further cannot control the rate of the UE according to the APN AMBR.

Based on the network architecture shown in fig. 1 and the existing problems, an embodiment of the present application provides a session establishment method and a session transfer method, which are used for implementing a session establishment and transfer process in a process of moving a UE from a 5G communication system to a 4G communication system.

Fig. 2 is a schematic structural diagram of a UE according to an embodiment of the present application, and in various embodiments of the present application, it should be understood that the UE may be a user equipment such as a mobile phone, a tablet Computer, a notebook Computer, an Ultra-mobile Personal Computer (UMPC), a netbook, a Personal Digital Assistant (PDA), a mobile phone chip (e.g., a modem chip), a mobile station, and a wearable device. The embodiment of the present application is described by taking a UE as a mobile phone as an example, where the UE includes: a Radio Frequency (RF) circuit 210, a memory 220, an input unit 230, a display unit 240, a gravity sensor 250, an audio circuit 260, a processor 270, and a 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 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 120. 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 170 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 separate 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 (Gravity Sensor)350 may detect the acceleration of the mobile phone in each direction (generally, three axes), detect the Gravity and direction 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), vibration recognition related functions (such as pedometer, tapping), and the like. 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 262 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 illustrating a first embodiment of a session establishment method provided in an embodiment of the present application, and as shown in fig. 3, the session establishment method includes the specific steps of:

s101: the UE sends a first message to the AMF, and the first message is used for establishing the PDU session.

In this step, the first message includes a PDU session setup request and priority information indicating a priority for the UE to currently request the setup of the PDU session to be transferred from the 5G communication system to the 4G communication system. The priority information may be carried in the PDU session establishment request or may be outside the PDU session establishment request, and the present solution is not limited.

Optionally, the first message sent by the UE to the AMF may also carry: single Network Slice Selection Assistance Information (S-NSSAI), Data Network Name (DNN), PDU session id (session identity), Request type (Request type).

The first message may specifically be a NAS message sent by the UE to the AMF, for example, a UL NAS transport message, and the setting of the request type to initial indicates that the PDU session is to be established.

The PDU session setup request may be sent to the AMF contained in an N1 session management container (N1 SM container).

According to this step, the UE needs to acquire the priority information before initiating the PDU session establishment, and in a specific implementation, the UE may determine the priority information according to one or a combination of multiple types of information: the UE requests the S-NSSAI corresponding to the established PDU session; an application using the PDU session; a UE routing Policy (URSP) stored in the UE; and the UE requests the QoS parameters of the QoS flow corresponding to a default Quality of Service (QoS) rule (rule) of the established PDU session.

Optionally, each network slice corresponding to S-NSSAI in the UE has a priority, and the UE may determine priority information according to the priority corresponding to the S-NSSAI; or, different applications on the UE correspond to different priorities, and the UE may determine the priority information according to the priority corresponding to the application using the PDU session. Specifically, the UE may determine the priority information according to an Identification (ID) of the application or a type (type) of the application; or, storing the priority corresponding to each S-NSSAI and/or application in the URSP of the UE (including three cases, i.e., the priority corresponding to the S-NSSAI, the priority corresponding to the application, -NSSAI, and the priority corresponding to the application), and the UE determining the priority information according to the URSP; alternatively, the UE determines the priority information according to a QoS parameter of a QoS flow associated with the default QoS rule in the PDU session, for example, 5 QI.

Where in this application reference is made to "in accordance with", this is to be understood as a reference to "at least in accordance with", i.e. other conditions may be included in addition to the conditions of the basis given herein, which is not further defined herein. For example, determining the priority information according to the priority corresponding to the S-NSSAI is understood as determining the priority information according to at least the priority corresponding to the S-NSSAI, i.e., the determination may be performed according to other information besides the S-NSSAI. The other parts are the same as the understanding, and are not described again.

Here, the Priority of the PDU session transferred from the 5G communication system to the 4G communication system may specifically be understood as a Priority of switching from 5G to 4G procedure, PDU session switching (handover) or transfer (transfer or move) to 4G when the UE is in a connected state, and in this case, the Priority may also be understood as a handover Priority; alternatively, in the idle state, during the movement (transfer) of the UE from 5G to 4G, the PDU session is transferred to the Priority of 4G, and in this case, the Priority may also be understood as transfer Priority. Subsequently, the priority of the PDU session transferred from the 5G communication system to the 4G communication system or the priority of the PDU session transferred to the 4G communication system is the same as that understood and is not described again.

After the AMF completes the establishment of the PDU session according to the received information, a PDU session establishment Accept (Accept) is returned to the UE, i.e. the UE performs step S104.

S102: and the SMF + PGW-C acquires the priority information of the PDU session transfer of the UE to the 4G communication system in the PDU session establishment process of the UE.

In this step, after receiving the first message sent by the UE, the AMF selects an appropriate SMF + PGW-C, and sends the PDU session establishment request to the selected SMF + PGW-C.

The SMF + PGW-C needs to acquire the priority information of the PDU session established by the UE in the PDU session establishment process of the UE, and the priority information is used for indicating the priority of the PDU session transferred to the 4G communication system; or, the priority information is used for indicating the priority of the PDU session transferred to the 4G communication system; or, the priority information is used for enabling the AMF or the SMF + PGW-C to know the priority of the PDU session transferred to the 4G communication system; or, the priority information is used for enabling the AMF or the SMF + PGW-C to determine the priority of the PDU session transferred to the 4G communication system.

The specific ways for the SMF + PGW-C to acquire the priority information of the PDU session at least include the following:

in a first mode, the priority information is a priority of the received PDU session transferred to the 4G communication system sent by the UE.

In a second manner, the priority information is the priority of the PDU session transfer to the 4G communication system, which is determined by the SMF + PGW-C according to the S-NSSAI of the PDU session;

in a third mode, the priority information is the priority of transferring the PDU session to the 4G communication system, which is determined by the SMF + PGW-C according to the S-NSSAI and DNN of the PDU session;

in a fourth mode, the priority information is the priority of transferring the PDU session to a 4G communication system, which is determined by the SMF + PGW-C according to the QoS parameter of the QoS flow of the PDU session, wherein the QoS parameter of the QoS flow is associated with a default QoS rule;

in a fifth mode, the priority information is a priority for receiving the PDU session sent by the AMF and transferring to the 4G communication system, and the priority information is sent to the SMF + PGW-C after the AMF receives the priority for transferring the PDU session sent by the UE to the 4G communication system, or the priority information is a priority for transferring the PDU session to the 4G communication system determined by the AMF according to the S-NSSAI or S-NSSAI and DNN of the PDU session.

S103: the SMF + PGW-C sends the priority information to the UDM + HSS or the AMF.

In this step, after acquiring the priority information of the PDU session, the SMF + PGW-C may send the priority information of the PDU session to the UDM + HSS for storage, or to the AMF.

S104: and the UE receives the AMF and sends a second message, wherein the second message comprises PDU session establishment acceptance.

The second message may specifically be a NAS message, such as a DL NAS transport message, sent by the AMF to the UE.

In this step, after completing the PDU session establishment according to the PDU session establishment request sent by the UE, the AMF returns a second message to the UE, where the second message at least includes a PDU session establishment acceptance for notifying the UE that the PDU session establishment is completed.

In an optional implementation manner of the scheme, the second message may also carry priority information of the PDU session determined by the network side. Optionally, the priority information may be determined by AMF or SMF + PGW-C.

In the session establishment method provided in this embodiment, the UE sends a PDU session establishment request to the AMF on the network side, and the AMF selects the combined SMF + PGW-C to complete the PDU session establishment procedure, and returns a PDU session establishment acceptance to the UE to complete the PDU session establishment procedure.

In the embodiments of the present application, it should be understood that the UE moves from the 5G communication system to the 4G communication system, and specifically, it may be understood as a process that when the UE is in an overlapping coverage area of the 5G and the 4G, the UE disconnects from the 5G and accesses the 4G. Specifically, it may be that, due to signal coverage, the UE loses 5G coverage and enters 4G; or the UE determines to enter 4G according to the local policy. The UE moving from 5G to 4G can be specifically divided into two cases: the UE enters 4G from 5G in a switching (handover) mode in a connected state; the UE reselects (select or reset) from 5G to 4G in the idle state.

Fig. 4 is a flowchart illustrating a first embodiment of a session transfer method provided in an embodiment of the present application, and as shown in fig. 4, after the PDU session establishment procedure is completed, when a UE moves from a 5G communication system to a 4G communication system, a PDU session needs to be transferred, where the session transfer method provided in this embodiment includes:

s201: when the UE moves from the 5G communication system to the 4G communication system, the AMF sends information of PDN connection corresponding to the first PDU session to the MME.

In the scheme, when the AMF detects that the UE moves from the 5G communication system to the 4G communication system, the AMF determines a first PDU session to be transferred in the PDU session of the UE. The first PDU session is a PDU session with highest priority transferred to the 4G communication system among a plurality of PDU sessions established by the UE and using the first DNN. Specifically, the AMF may determine the first PDU session according to the priority information of the plurality of PDU sessions corresponding to the DNN. The AMF detects that the UE moves from the 5G communication system to the 4G communication system includes 2 cases: when the UE is in a connected state, the AMF receives a request for switching to the 4G from the 5G RAN, and detects that the UE moves from the 5G communication system to the 4G communication system according to the request; or, the UE initiates a Tracking Area Update (TAU) request to the MME in an idle state, the MME sends a UE Context (Context) request message to the AMF in a TAU procedure, and the AMF detects that the UE moves from the 5G communication system to the 4G communication system according to the request

Here, the PDU session using the first DNN may be understood as that, in the process of establishing the PDU session, the UE carries the first DNN, thereby completing the establishment process of the PDU session; or, in the process of establishing the PDU session, the network side entity (AMF or SMF + PGW-C) selects the first DNN for the UE, thereby completing the establishment process of the PDU session.

Therefore, the AMF needs to acquire the priority information of multiple PDU sessions using the DNN on the UE in advance, and specifically may acquire the priority information in the following ways:

in a first manner, taking a first PDU session as an example, in a process of establishing the first PDU session, the AMF receives priority information sent by the UE.

In the scheme, that is, in the process of PDU session establishment in the 5G communication system, the UE may send the priority information to the AMF, where the priority information may be carried in or outside the PDU session establishment request and sent using the same message as the PDU session establishment request, or may be sent to the AMF separately, which is not limited in this scheme.

The priority information sent by the UE at least includes: the priority of the S-NSSAI corresponding to the PDU session; or, the priority of S-NSSAI and DNN corresponding to the PDU session; or, a priority of an application using the PDU session; or, a QoS parameter of a QoS flow of the PDU session associated with a default QoS rule. Each network slice corresponding to the S-NSSAI in the UE has a priority, and the UE can carry the priority corresponding to the S-NSSAI; or each S-NSSAI and DNN in the UE has a priority, and the UE may carry the priority corresponding to the S-NSSAI and DNN; or, different applications on the UE correspond to different priorities, and the UE may carry the priority corresponding to the application using the PDU session. Specifically, the UE may determine the priority according to an Identification (ID) of the application or a type (type) of the application; alternatively, the priority may be determined based on a QoS parameter of a QoS flow associated with a default QoS rule in the PDU session, e.g., 5 QI.

In a second manner, taking a first PDU session as an example, the AMF receives priority information of the first PDU session sent by a first SMF + PGW-C.

In the scheme, for each PDU session, the AMF may receive priority information of the PDU session sent by the SMF + PGW-C corresponding to each PDU session, respectively. The priority information may specifically include the following implementations: the AMF receives an Allocation and Retention Priority (ARP) corresponding to a default quality of service rule corresponding to the first PDU session sent by the first SMF + PGW-C.

Or, the AMF receives the priority of the S-NSSAI corresponding to the first PDU session sent by the first SMF + PGW-C.

Or, the AMF receives and stores the priority provided by the UE and sent by the first SMF + PGW-C.

In a specific implementation of the scheme, taking a first PDU session as an example, the AMF may receive priority information of the first PDU session sent by a first SMF + PGW-C in an EBI allocation process; or, the AMF receives, in an EBI allocation process, information sent by the first SMF + PGW-C for determining the priority of the first PDU session.

Optionally, in this process, the AMF may determine, according to the identifier of the first PDU session, a first DNN corresponding to the first PDU session.

Optionally, the information used for determining the priority of the first PDU session may specifically be an identifier of the first PDU session, and the AMF determines the priority information corresponding to the first PDU session according to the identifier of the first PDU session. Specifically, the AMF stores a correspondence between a PDU session identifier of each PDU session and a priority of the PDU session transferred to the 4G communication system, and determines the priority information according to the correspondence and the first PDU session identifier.

Specifically, the EBI allocation process specifically includes the following implementation manners:

(1) the AMF receives an EBI allocation request sent by the first SMF + PGW-C; and if the AMF determines that the EBI is already allocated to the second PDU session corresponding to the first DNN, and the second PDU session corresponding to the second SMF + PGW-C is different from the first SMF + PGW-C, judging whether the priority of the first PDU session is higher than that of the second PDU session. And if the priority of the first PDU session is higher than that of the second PDU session, the AMF allocates EBI for the first PDU session.

Optionally, the AMF further initiates a process of deleting the EBI corresponding to the second PDU session.

Optionally, when the AMF determines that the priority of the first PDU session is lower than the priority of the second PDU session, the AMF does not allocate an EBI to the first PDU session, and carries a reject reason, where the reject reason is used to enable the first SMF + PGW to know that the AMF allocates an EBI to a higher-priority PDU session.

In this scheme, also taking the first PDU session as an example, after receiving an EBI allocation request sent by the first SMF + PGW-C corresponding to the first PDU session, the AMF needs to determine, according to the content stored locally, whether to already allocate an EBI to the DNN of the first PDU session, that is, to allocate an EBI to another PDU session corresponding to the first DNN, for example, to the second PDU session. If the second PDU session is already allocated with EBI, it needs to determine whether a first SMF + PGW-C corresponding to the first PDU session and a second SMF + PGW-C corresponding to the second PDU session are the same SMF + PGW-C, if not, it needs to determine whether to allocate EBI for the first PDU session according to the priority of the two PDU sessions, specifically, when the priority of the first PDU session is higher than the priority of the second PDU session, the AMF allocates EBI for the first PDU session, otherwise, the AMF does not allocate EBI for the first PDU session, and the first PDU session cannot be transferred.

Optionally, when the AMF determines that the priority of the first PDU session is lower than the priority of the second PDU session, the AMF does not allocate an EBI to the first PDU session, and carries a reject reason, where the reject reason is used to enable the first SMF + PGW to know that the AMF allocates an EBI to a higher-priority PDU session. In various embodiments of the present application, it should be understood that the first PDU session corresponding to the first SMF + PGW-C may be understood as: the first SMF + PGW-C serves the first PDU session. Alternatively, the first PDU session uses the first SMF + PGW-C. Or, in the first PDU session establishment process, the AMF selects a first SMF + PGW-C for the first PDU session. Or, the first SMF + PGW-C allocates an IP address for the first PDU session.

Likewise, the second PDU session corresponding to the second SMF + PGW-C may be understood as: the second SMF + PGW-C serves the second PDU session. Alternatively, the second PDU session uses a second SMF + PGW-C. Or, in the second PDU session establishment process, the AMF selects a second SMF + PGW-C for the second PDU session. Or the second SMF + PGW-C allocates an IP address for the second PDU session.

(2) The AMF receives an EBI allocation request sent by the first SMF + PGW-C; and if the AMF determines that EBI is already allocated to the third PDU session corresponding to the first DNN and the third PDU session corresponds to the first SMF + PGW-C, the AMF allocates EBI to the first PDU session.

In this scheme, the AMF receives an EBI allocation request sent by the first SMF + PGW-C, and specifically, the SMF + PGW-C invokes (invoke) a service provided by the AMF, for example, AMF communicates EBI allocation (Namf _ Communication _ ebiaassignment request), or the SMF + PGW-C initiates the EBI allocation request to the AMF.

After receiving the EBI allocation request sent by the first SMF + PGW-C corresponding to the first PDU session, the AMF needs to determine, according to the content stored locally, whether EBI has been allocated to the DNN of the first PDU session, that is, to other PDU sessions corresponding to the first DNN, for example, the third PDU session. If the EBI has already been allocated to the third PDU session, it needs to determine whether the third PDU session corresponds to the same SMF + PGW-C as the first PDU session, that is, it determines whether the third PDU session also corresponds to the first SMF + PGW-C, and if so, directly allocates the EBI to the first PDU session, so as to subsequently continue to perform the session transfer procedure.

(3) The AMF receives an EBI allocation request sent by the first SMF + PGW-C; and if the AMF determines that the first DNN corresponds to a second SMF + PGW-C which is locally stored, and the priority corresponding to the first SMF + PGW-C is higher than the priority corresponding to the second SMF + PGW-C, the AMF allocates EBI for the first PDU session.

In this scheme, after receiving an EBI allocation request sent by a first SMF + PGW-C corresponding to the first PDU session, the AMF needs to determine, according to locally stored content, whether the DNN of the first PDU session is already stored, that is, other SMF + PGW-C corresponding to the first DNN, that is, the second SMF + PGW-C. If so, determining whether to allocate the EBI for the first PDU session according to the priorities of the first SMF + PGW-C and the second SMF + PGW-C, and allocating the EBI for the first PDU session by the AMF only when the priority corresponding to the first SMF + PGW-C is higher than the priority corresponding to the second SMF + PGW-C. Otherwise, the AMF does not allocate the EBI for the first PDU session, and the first PDU session cannot be transferred.

(4) The AMF receives an EBI allocation request sent by the first SMF + PGW-C; and if the AMF determines that the first DNN corresponds to a first SMF + PGW-C, the AMF allocates an EBI for the first PDU session.

In this scheme, after receiving an EBI allocation request sent by a first SMF + PGW-C corresponding to the first PDU session, the AMF needs to determine, according to locally stored content, whether the DNN of the first PDU session is already stored, that is, other SMF + PGW-C corresponding to the first DNN, that is, the second SMF + PGW-C. If not, the AMF directly distributes the EBI for the first PDU session.

In the specific implementation of the foregoing schemes, the AMF may determine, according to the priority of the S-NSSAI or the slice or slice instance (instance) corresponding to the stored SMF + PGW-C, the priority corresponding to the first SMF + PGW-C and the priority corresponding to the second SMF + PGW-C. Or, the AMF acquires the corresponding priority of each SMF + PGW-C. In actual networking, different slices may correspond to different priorities, for example, a government slice has a higher priority than an enterprise slice, and the AMF may determine the priority of the SMF + PGW-C in a slice according to different slices. The AMF may also maintain the priority of each SMF + PGW-C.

Thus, AMF may determine the priority of SMF + PGW-C. After the AMF determines that the first PDU session is to be transferred, the AMF needs to obtain information of the PDN connection in the 4G communication system corresponding to the first PDU session, and send the information to the MME. In a specific implementation, the AMF obtains a first PDU session with a highest priority in a plurality of PDU sessions corresponding to the first DNN, that is, determines to transfer the first PDU session, and then requests, to a first SMF + PGW-C corresponding to the first PDU session, information of PDN connection corresponding to the first PDU session. And then sending the obtained PDN connection information corresponding to the first PDU session to the MME for PDN connection. The PDU session corresponds to PDN connection, which can be understood as that the PDU session and PDN connection use the same IP address; or the PDU session and the PDN connection have the same IP address and SMF + PGW-C; alternatively, the PDU session has the same IP address and SMF + PGW-C and UPF + PGW-U as the PDN connection.

Or,

and the AMF requests the information of the PDN connection corresponding to the first PDU session from a first SMF + PGW-C corresponding to the first PDU session, and acquires the information of the PDN connection corresponding to other PDU sessions using the first DNN. Before, at the same time or after the AMF requests the first SMF + PGW-C for the information of the PDN connection corresponding to the first PDU session, the AMF may also request the first SMF + PGW-C for the SMF + PGW-C corresponding to the other PDU session corresponding to the first DNN, and request the information of the PDN connection corresponding to the other PDU session.

In a specific implementation of the solution, in addition to sending, by the AMF, to the MME, information of a PDN connection corresponding to the first PDU session, the AMF may also send information of a PDN connection of a fourth PDU session using the same DNN and SMF + PGW-C as the first PDU session, where the fourth PDU session may be one or more. After obtaining the PDN connection corresponding to the fourth PDU session, the MME may transfer the PDU session using the same DNN and SMF + PGW-C as the first PDU to 4G.

S202: and the MME establishes PDN connection for the UE in the 4G communication system according to the PDN connection information corresponding to the first PDU session.

In this step, after receiving the information of the PDN connection corresponding to the first PDU Session sent by the AMF, the MME selects a Serving gateway Serving GW for the UE, and sends a Create Session Request to the Serving GW, thereby creating the PDN connection for the UE.

In the above scheme, the MME determines which PDU session of the UE is to be transferred to the 4G communication system according to the priority information of the PDU session, and in the session transfer scheme, the UE may also determine which PDU session is to be transferred, specifically, when the UE moves from the 5G communication system to the 4G communication system, the UE determines the first PDU session to be transferred to the 4G communication system according to the priority information of each PDU session corresponding to the DNN used (i.e., the first DNN in the above scheme). In one specific implementation, the method can be as follows: and the UE determines the PDU session with the highest priority as the first PDU session transferred to the 4G communication system according to the priority information corresponding to each PDU session corresponding to the DNN.

Specifically, after entering the 4G system, the UE may enable a context corresponding to the PDN connection; or the UE actively initiates a PDN connection establishment request in 4G, so that the PDN connection is established.

In the session transfer method provided in the foregoing embodiment, the UE sends, to the AMF, priority information indicating a priority for transferring the PDU session requested to be established by the UE to the 4G communication system in the PDU session establishment process in the 5G communication system, and when the PDU session of the UE needs to be transferred to the 4G communication system subsequently, the AMF or the MME or the UE determines which PDU session is to be transferred to the 4G communication system according to the priority information of each PDU session, and performs the subsequent session transfer process, and completes PDN connection establishment in the 4G system, thereby achieving the purpose of selectively transferring the PDU session in the process of moving the UE from the 5G communication system to the 4G communication system.

On the basis of the above embodiment, in the PDU session establishment process, the UDM + HSS may store the correspondence between addresses and priorities of DNN, SMF + PGW-C used by the PDU session of the UE; the priority is used for indicating the priority of transferring the PDU session corresponding to the SMF + PGW-C to the 4G communication system, or the priority is used for indicating the priority of transferring the SMF + PGW-C to the 4G communication system. And in the process of transferring the PDU session to the 4G communication system, the UDM + HSS determines a first SMF + PGW-C address used by the UE in the 4G communication system according to the stored priority, and then the UDM + HSS sends the determined first SMF + PGW-C address and APN to the MME, wherein the APN corresponds to the DNN used by the PDU session of the UE. And after the MME receives the APN and the first SMF + PGW-C address, establishing PDN connection for the UE according to the APN and the first SMF + PGW-C address, and completing the PDU session transfer to the 4G communication system. The priority of the SMF + PGW-C transferred to the 4G communication system may also be understood as the priority of the SMF + PGW-C transferred to the 4G communication system, which may be the priority of all PDU sessions corresponding to the SMF + PGW-C transferred to the 4G communication system, or the priority of all PDU sessions corresponding to the SMF + PGW-C transferred to the 4G communication system with the highest priority.

The address of SMF + PGW-C may specifically be: an identification of SMF + PGW-C, or an FQDN (Fully Qualified Domain Name) of SMF + PGW-C, or an IP address of SMF + PGW-C.

In the process, in a specific implementation manner, the UDM + HSS may store a correspondence between addresses and priorities of SMF + PGW-cs of multiple PDU sessions corresponding to the DNN, so that in the process of determining the first SMF + PGW-C address, the UDM + HSS determines, as the first SMF + PGW-C address, an address of an SMF + PGW-C having the highest priority among all SMF + PGW-cs corresponding to the DNN.

In another specific implementation manner, the UDM + HSS may only store the correspondence between the address and the priority of the DNN, the SMF + PGW-C corresponding to one PDU session, where the specific storage process is as follows: and the UDM + HSS receives the DNN, the SMF + PGW-C address and the priority sent by the SMF + PGW-C, and determines whether the corresponding relation between other SMF + PGW-C corresponding to the DNN and the priority is stored.

If so, the UDM + HSS judges whether the priority corresponding to the SMF + PGW-C is higher than the priority corresponding to the other stored SMF + PGW-C corresponding to the DNN, and if so, the UDM + HSS stores the corresponding relation between the address of the SMF + PGW-C and the priority.

The meaning of the scheme is that the UDM + HSS only stores the corresponding relation between the address and the priority of the SMF + PGW-C with the highest priority.

The corresponding relationship between DNN, SMF + PGW-C and priority includes: corresponding relation among APN corresponding to DNN, SMF + PGW-C and priority; or the corresponding relation between DNN, S-NSSAI, SMF + PGW-C and priority; or the corresponding relation among the APN corresponding to the DNN, the S-NSSAI, the SMF + PGW-C and the priority; or, the PDU session identifier, the SMF + PGW-C and the priority.

Optionally, in the PDU session establishment process, the UDM + HSS may store a correspondence between addresses and priorities of an APN, an SMF + PGW-C used in the transfer of the PDU session of the UE to the 4G communication system; the priority is used for indicating the priority of transferring the PDU session corresponding to the SMF + PGW-C to the 4G communication system, or the priority is used for indicating the priority of transferring the SMF + PGW-C to the 4G communication system. And in the process of transferring the PDU session to the 4G communication system, the UDM + HSS determines a first SMF + PGW-C address used by the UE in the 4G communication system according to the stored priority, and then the UDM + HSS sends the first SMF + PGW-C address and the APN corresponding to the first SMF + PGW-C address to an MME. The APN corresponds to a DNN used by a PDU session of the UE. And after the MME receives the APN and the first SMF + PGW-C address, establishing PDN connection for the UE according to the APN and the first SMF + PGW-C address, and completing the PDU session transfer to the 4G communication system.

In a specific implementation manner of the scheme, the UDM + HSS may store a correspondence between addresses and priorities of SMF + PGW-cs of a plurality of PDU sessions, and therefore, in a process of determining an address of a first SMF + PGW-C, the UDM + HSS determines, according to the correspondence, an address of an SMF + PGW-C having a highest priority among the stored SMF + PGW-cs as an address of the first SMF + PGW-C.

In another specific implementation manner, the UDM + HSS may store a correspondence between an APN corresponding to one PDU session, an address and a priority of an SMF + PGW-C, and in a specific storage process, the UDM + HSS receives an APN, an address and a priority of an SMF + PGW-C sent by the SMF + PGW-C, and determines whether a correspondence between other SMF + PGW-cs corresponding to a DNN corresponding to the APN and the priority is locally stored. If so, the UDM + HSS judges whether the priority corresponding to the SMF + PGW-C is higher than the priority corresponding to the other stored SMF + PGW-C corresponding to the DNN, and if so, the UDM + HSS stores the corresponding relation between the SMF + PGW-C and the priority.

The meaning of the scheme is that only the corresponding relation between the address and the priority of the SMF + PGW-C with the highest priority is stored in the UDM + HSS.

The correspondence between the APN, the SMF + PGW-C and the priority includes: corresponding relation among APN corresponding to DNN, SMF + PGW-C and priority; or the corresponding relation between DNN, S-NSSAI, SMF + PGW-C and priority; or the corresponding relation among the APN corresponding to the DNN, the S-NSSAI, the SMF + PGW-C and the priority; or, the PDU session identifier, the SMF + PGW-C and the priority.

Based on the various embodiments, the main idea of the above solution is: still maintain the restriction of one-to-one mapping of DNN and APN, but only transfer the PDU session of one slice corresponding to DNN to the 4G communication system, specifically include the following two scenarios:

there are N26 scenarios: the AMF determines which network slice PDU session can be transferred to the 4G communication system. In the session transfer process under this scenario:

when SMF + PGW-C requests the AMF to allocate an EBI, the AMF decides which PD session can be transferred to 4G according to priority.

For PDU sessions that cannot be transferred to 4G, AMF does not allocate EBI or recycles allocated EBI

Specifically, the AMF is based on priorities of:

the priority of the S-NSSAI held locally by the AMF, or,

the priority of the S-NSSAI provided by SMF + PGW-C to AMF, or,

the SMF + PGW-C provides ARP corresponding to the default QoS rule corresponding to the PDU session to the AMF,

the information provided by the SMF + PGW-C to the AMF may be provided to the SMF by the UE.

No N26 scenario: the UDM + HSS judges which slice of PDU session can be transferred to the 4G communication system, and in the session transfer process under the scene:

-the SMF + PGW-C providing the UDM + HSS saved information with priority information, comprising:

the UDM + HSS only stores the corresponding relation between the APN which can be transferred to the 4G and the SMF + PGW-C; or the UDM + HSS stores the corresponding relation among the APN, the SMF + PGW-C and the priority.

Specifically, the UDM + HSS stores the correspondence with DNN, SMF + PGW-C, and priority, including:

the UDM + HSS stores the corresponding relation between the APN corresponding to the DNN, the SMF + PGW-C and the priority; or,

the UDM + HSS stores the corresponding relation between DNN, S-NSSAI, SMF + PGW-C and priority; or,

the UDM + HSS stores the corresponding relation between the APN, the S-NSSAI, the SMF + PGW-C and the priority corresponding to the DNN; or,

and the UDM + HSS stores the corresponding relation among the PDU session ID, the SMF + PGW-C and the priority.

Optionally, the UDM + HSS stores a correspondence relationship between the APN, the SMF + PGW-C, and the priority, including:

corresponding relation of DNN, S-NSSAI, SMF + PGW-C and priority; or,

and the PDU session identification, the SMF + PGW-C and the priority.

Specifically, the priority provided by the SMF to the UMD + HSS is the ARP corresponding to the default QoS rule corresponding to the PDU session, or the priority provided by the SMF from the UE, or the priority of the S-NSSAI, etc.

Based on the above idea, the session establishment method and the session transfer method provided by the first solution are described below by two specific examples.

Fig. 5 is a flowchart illustrating a first embodiment of a session establishment method with an N26 interface scenario provided in the embodiment of the present application, where as shown in fig. 5, the session establishment method specifically includes the following steps:

s301: the UE sends a PDU session setup request to the AMF.

In this step, the UE initiates a PDU session establishment request in the 5G communication system, optionally, the priority of transferring the PDU session to the 4G communication system or the priority of transferring the S-NSSAI corresponding to the PDU session to the 4G communication system or the priority of the application using the PDU session on the UE is carried.

S302: and the AMF selects the SMF + PGW-C according to the S-NSSAI and the DNN, and sends a PDU session establishment SM context request to the selected SMF + PGW-C. The PDU session setup request is included in the request.

In this step, the AMF selects SMF + PGW-C according to the S-NSSAI and DNN, and sends a PDU session creation SM context request to the SMF + PGW-C, where the request carries a PDU session identifier, the S-NSSAI and the DNN, and optionally carries the priority in step S301.

S303: and the SMF + PGW-C requests the subscription information corresponding to the DNN from the UDM + HSS. This step S303 is an optional step.

S304: SMF + PGW-C determines that the PDU session can be transferred to 4G, and requests the AMF to allocate an EBI.

In this step, the SMF + PGW-C determines that the PDU session can be transferred to the 4G communication system, and then requests the AMF to allocate an EBI, optionally, priority information may be carried in the EBI allocation request.

The priority information may be the priority carried by the UE to SMF + PGW-C in S301. Or the SMF + PGW-C determines the priority according to the priority of the locally stored S-NSSAI; or, the priority of the PDU session determined by the SMF + PGW-C is not limited in this scheme.

The AMF determines whether to allocate an EBI for the PDU session S305.

In this step, the AMF determines, according to the PDU session identifier, a DNN corresponding to the PDU session, further determines whether the DNN corresponds to another SMF + PGW-C, and if so, compares priorities corresponding to the newly requested SMF + PGW-C and the saved SMF + PGW-C. And if the newly requested priority is high, allocating the EBI to the PDU session, and deleting the EBI of the PDU corresponding to the original SMF + PGW-C.

Specifically, AMF is based on a priority of

The priority of the S-NSSAI corresponding to the SMF + PGW-C locally stored by the AMF, or,

SMF + PGW-C provides the AMF with priority.

The priority provided by the SMF + PGW-C to the AMF is specifically as follows:

the SMF + PGW-C provides the AMF with the ARP corresponding to the default QoS rule corresponding to the PDU session, or,

the priority of the S-NSSAI corresponding to the PDU session provided by SMF + PGW-C to AMF, or,

the SMF + PGW-C receives the priority provided by the UE and sends it to the AMF, or,

SMF + PGW-C's own priority.

S306: and the AMF determines the EBI corresponding to the low-priority SMF + PGW-C corresponding to the DNN and initiates a process of recovering the EBI.

In the scheme, the AMF determines to allocate the EBI for the PDU session corresponding to the SMF + PGW-C corresponding to the DNN with the high priority corresponding to the DNN, and then the EBI corresponding to the SMF + PGW-C with the low priority can initiate a process of recovering the EBI.

S307: AMF returns an EBI allocation response to SMF + PGW-C.

S308: the SMF + PGW-C returns a PDU session creation SM context response to the AMF.

S309: the AMF returns a PDU session establishment acceptance to the UE.

And in the steps, the PDU session establishment process is completed according to the SMF + PGW-C, the EBI distributed for the SMF + PGW-C and other information.

In the session establishment method under the scenario of the N26 interface provided in this embodiment, the UE initiates a session establishment request, and in the session establishment process, the SMF + PGW-C determines whether a PDU session requested by the UE can be transferred to the 4G communication system according to the obtained priority information, and then requests to allocate an EBI to complete a subsequent session establishment process, so that when a session transfer needs to be performed, the AMF can determine which PDU session is to be transferred. PDU session establishment is achieved, and meanwhile preparation is made for selective transfer of PDU sessions during movement of the UE from the 5G communication system to the 4G communication system.

Fig. 6 is a flowchart illustrating a first embodiment of a session transfer method without an N26 interface scenario provided in the embodiment of the present application, where as shown in fig. 6, the session transfer method specifically includes the following steps:

s401: the UE sends a PDU session setup request to the AMF.

In this step, the UE initiates a PDU session establishment request, optionally, the priority of transferring the PDU session to 4G or the priority of transferring the S-NSSAI corresponding to the PDU session to 4G is carried.

S402: and the AMF selects the SMF + PGW-C according to the S-NSSAI and the DNN, and sends a PDU session establishment SM context request to the selected SMF + PGW-C.

In this step, the AMF selects SMF + PGW-C according to the S-NSSAI and the DNN, and sends a request to the SMF + PGW-C, wherein the request carries the PDU session identifier, the S-NSSAI and the DNN. Optionally, the priority may also be carried.

S403: and the SMF + PGW-C requests the subscription information corresponding to the DNN from the UDM + HSS. This S403 is an optional step.

S404: the SMF + PGW-C returns a PDU session creation SM context response to the AMF.

S405: the AMF returns a PDU session establishment acceptance to the UE.

And according to the steps, finishing the PDU session establishment process.

S406: and the SMF + PGW-C sends the corresponding relation between the SMF + PGW-C address and the priority to the UDM + HSS.

In this step, the SMF + PGW-C sends the corresponding relationship between the SMF + PGW-C address and the Priority to the UDM + HSS, and optionally, the SMF + PGW-C further sends the APN or DNN to the UDM + HSS, that is, the SMF + PGW-C sends the corresponding relationship between the APN or DNN, the SMF + PGW-C address and the Priority to the UDM + HSS. In a specific implementation, the method for determining the priority is similar to that in steps S304-S305 in fig. 5, and is not described herein again.

S407: and the UDM + HSS stores the corresponding relation among the APN, the SMF + PGW-C address and the priority.

In this step, the UDM + HSS storing the correspondence between APN, SMF + PGW-C address, and Priority includes at least the following two cases:

the UDM + HSS only stores the corresponding relation between the APN which can be transferred to the 4G and the SMF + PGW-C; or,

and the UDM + HSS stores the corresponding relation among the APN, the SMF + PGW-C and the priority.

S408: and the UDM + HSS sends the corresponding relation between the APN and the SMF + PGW-C to the MME.

According to the steps, if the UDM + HSS stores the corresponding relation among the APN, the SMF + PGW-C and the priority, the MME selects the SMF + PGW-C which can be transferred to the 4G communication system, and therefore the PDU session of the UE is transferred to the 4G communication system.

In the session transfer method provided in this embodiment, the corresponding relationship between the APN, the SMF + PGW-C, and the priority is stored in the UDM + HSS during the session establishment, and after the UE is transferred from the 5G communication system to the 4G communication system, the MME selects the SMF + PGW-C that can be transferred to the 4G communication system, thereby achieving the purpose of selectively transferring the PDU session during the UE moves from the 5G communication system to the 4G communication system.

Fig. 7 is a flowchart illustrating a second embodiment of a session establishment method provided in an embodiment of the present application, and as shown in fig. 7, the session establishment method includes the specific steps of:

s501: and the SMF + PGW-C receives a PDU session establishment request sent by the UE.

In this step, the UE initiates PDU session establishment in the 5G communication system, and the UE sends a PDU session establishment request to the SMF + PGW-C through the AMF, that is, the AMF needs to select the combined SMF + PGW-C for the UE. In one specific implementation, the PDU session setup request may carry a PDU session identifier, S-NSSAI, and DNN.

S502: and the SMF + PGW-C acquires the APN corresponding to the PDU session requested to be established by the UE.

In this step, the PDU session establishment request includes S-NSSAI and DNN, and the specific implementation manner for the SMF + PGW-C to acquire the APN corresponding to the PDU session requested to be established by the UE is that the SMF + PGW-C acquires the APN corresponding to the S-NSSAI and DNN, which specifically includes the following implementation manners:

in a first implementation manner, the SMF + PGW-C acquires the APN corresponding to the S-NSSAI and the DNN according to the stored policy information.

In the scheme, the policy information may be a local policy, an operator policy, a network slice usage policy, an APN usage policy, or the like, and the SMF + PGW-C acquires an APN corresponding to the S-NSSAI and the DNN according to the policy information. Specifically, the corresponding relation between the S-NSSAI and the DNN and the APN is stored in the strategy information, and the SMF + PGW-C acquires the APN according to the corresponding relation and the S-NSSAI and the DNN.

In a second implementation manner, the SMF + PGW-C acquires the APN corresponding to the S-NSSAI and the DNN according to the stored correspondence between the S-NSSAI and the DNN and the APN.

In this step, the SMF + PGW-C may determine the APN corresponding to the locally stored S-NSSAI, DNN and APN according to the correspondence between the S-NSSAI and DNN carried in the PDU session establishment request.

In addition to the above two implementation manners, if the PDU session establishment request received by the SMF + PGW-C includes the APN, the specific manner for the SMF + PGW-C to acquire the APN is to acquire the APN from the PDU session establishment request sent by the UE.

S503: SMF + PGW-C sends APN and SMF + PGW-C addresses to UDM + HSS.

After the SMF + PGW-C acquires the APN corresponding to the PDU session requested to be established by the UE, the address of the SMF + PGW-C and the APN are sent to the UDM + HSS, so that the UDM + HSS can store the corresponding relation between the APN and the address of the SMF + PGW-C.

S504: and the SMF + PGW-C sends PDU session establishment acceptance to the UE to complete the establishment process of the PDU session.

In this step, the SMF + PGW-C sends a PDU session establishment acceptance to the UE through the AMF, completing the PDU session establishment procedure.

In a specific implementation of the solution, if the PDU session establishment request sent by the UE does not carry the APN corresponding to the PDU session requested to be established, the APN is generated by the SMF + PGW-C or obtained according to the correspondence, when the PDU session establishment is completed, the PDU session establishment accept includes the APN, that is, the APN is sent to the UE for storage.

In the session establishment method of this embodiment, in the PDU session establishment process, the request carries S-NSSAI and DNN, so that the SMF + PGW-C obtains the APN of the PDU session requested to be established, that is, the APN and DNN are no longer in one-to-one correspondence, but in other words, the S-NSSAI and DNN are in correspondence with the APN, so that in the subsequent PDU session transfer process to the 4G communication system, the APN corresponding to the PDU session to be transferred can be determined according to the correspondence.

Fig. 8 is a flowchart illustrating a third embodiment of a session establishment method according to an embodiment of the present application, and as shown in fig. 8, on the basis of the embodiment shown in fig. 7, the specific steps of the session establishment method further include:

s505: and the SMF + PGW-C acquires APN-AMBR corresponding to the APN.

In this step, after the SMF + PGW-C acquires the APN corresponding to the PDU session requested to be established by the UE, it may also acquire an APN-AMBR corresponding to the APN, and the specific acquisition manner at least includes the following:

in a first obtaining mode, the SMF + PGW-C obtains the APN-AMBR corresponding to the APN according to the session AMBR of the UE.

The implication of this scheme is that the APN-AMBR is obtained by SMF + PGW-C according to the session-AMBR (i.e. session AMBR) of the UE in the 5G communication system. In a specific implementation manner, the SMF + PGW-C adds session AMBRs of all PDU sessions using DNN corresponding to the APN to obtain the APN-AMBR. Namely, the result is obtained by adding the session-AMBR of all PDU sessions using DNN and S-NSSAI corresponding to the first APN.

And in the second acquisition mode, the SMF + PGW-C acquires the APN-AMBR corresponding to the APN according to the subscription information of the UE.

Namely, the APN-AMBR is obtained by the SMF + PGW-C according to the subscription information of the APN which is in one-to-one correspondence with the DNN used by the UE.

S506: and the SMF + PGW-C sends the APN-AMBR corresponding to the APN to the UE.

S507: and the SMF + PGW-C sends the APN-AMBR corresponding to the APN to the UDM + HSS.

In the two steps, the SMF + PGW-C sends the APN-AMBR corresponding to the APN to the UE; and/or the SMF + PGW-C sends the APN-AMBR corresponding to the APN to the UDM + HSS.

And the SMF + PGW-C sends the APN-AMBR corresponding to the APN to the UE, so that the UE rate is controlled according to the APN-AMBR after the PDU session is transferred to the 4G communication system.

On the basis of the above scheme, in a specific implementation, the SMF + PGW-C sends first information to the UDM + HSS, where the first information is used for the UDM + HSS to determine an APN-AMBR corresponding to the APN.

Optionally, the first information includes: the APN-AMBR which is determined by the SMF + PGW-C and corresponds to the APN; or, a DNN corresponding to the PDU session; or the APN corresponding to the DNN corresponding to the PDU session is an APN having one-to-one correspondence with the DNN.

In the session establishment method provided in this embodiment, in the PDU session establishment process, while the SMF + PGW-C determines the APN according to the DNN used by the UE, the SMF + PGW-C acquires the APN-AMBR corresponding to the APN and sends the APN-AMBR to the UE, so that after the PDU session of the UE is transferred to the 4G communication system, the rate of the UE is controlled according to the APN-AMBR.

Fig. 9 is a flowchart illustrating a second embodiment of a session transfer method provided in the embodiment of the present application, and as shown in fig. 9, the session transfer method includes the specific steps of:

s601, when the UE determines to transfer the first PDU session to the 4G communication system, the UE acquires a first APN corresponding to the first PDU session.

In this step, after entering the 4G communication system, the UE determines that a certain first PDU session needs to be transferred, and may acquire a first APN corresponding to the first PDU session, so as to facilitate subsequent PDN connection usage, where specific implementation at least includes the following implementation manners:

in a first implementation manner, the UE acquires the first APN corresponding to the first PDU session according to the stored correspondence between the PDU session and the APN.

In this scheme, the correspondence between the PDU session and the APN includes: the corresponding relation between the S-NSSAI and DNN of the PDU session and the APN; or the corresponding relation between the PDU session identification of the PDU session and the APN.

The corresponding relationship may be obtained in the PDU session establishment process, for example: in the process of establishing the first PDU session, the UE receives a first APN which is sent by the SMF + PGW-C and corresponds to the first PDU session; and the UE acquires and stores the corresponding relation between the first PDU session and the first APN. Corresponding relations can also be obtained in the process of establishing other PDU sessions.

In a second implementation, the UE determines the first APN corresponding to S-NSSAI and DNN of the first PDU at least according to the URSP.

The URSP stored in the UE includes the S-NSSAI and the corresponding relationship between DNN and APN. Optionally, the routing description of the URSP includes S-NSSAI and a correspondence between DNN and APN.

The URSP is sent to the UE by a network side entity PCF + PCRF after the UE receives the message.

In a third implementation, the UE generates the first APN corresponding to S-NSSAI and DNN of the first PDU.

Optionally, the UE dynamically generates the first APN.

S602: and the UE sends a PDN connection establishment request to the MME.

In this step, the PDN connection establishment request carries the first APN corresponding to the first PDU session, so that the MME performs session establishment according to the APN.

S603: and the UE receives PDN connection establishment acceptance sent by the MME.

And the UE receives PDN connection establishment acceptance returned by the MME or receives a PDN connection establishment response to complete the PDN connection, namely the PDU session of the UE is transferred to the 4G communication system.

In a specific implementation of the foregoing scheme, the UE receives a first APN-AMBR corresponding to the first PDU session, where the first APN-AMBR is sent by an SMF + PGW-C.

The first APN-AMBR is an AMBR corresponding to the first PDU session, and the UE may control a rate according to the APN-AMBR after the PDU session of the UE is transferred into the 4G communication system.

In the session transfer method provided by this embodiment, in the PDU session establishment process, the UE determines the APN corresponding to the PDU session to be created, and sends the APN to the SMF + PGW-C, and the UE locally stores the correspondence between the PDU session and the APN, and in the process of moving the UE from the 5G communication system to the 4G communication system, the UE may determine the APN corresponding to the PDU session to be transferred, thereby implementing selective transfer of the PDU session.

Based on the above embodiments, the main idea of the second solution is as follows: breaking the restriction of one-to-one mapping of DNN and APN, modifying to:

in particularThe implementation includes at least two implementation ideas.

The realization idea 1: the SMF + PGW-C sends APN to the UE.

And when the UE establishes the PDU session in the 5G, the SMF + PGW-C generates a corresponding APN according to the S-NSSAI and the DNN and sends the APN to the UE. Optionally, the UE is sent through PCO.

And under the scene of no N26, the SMF + PGW-C further sends the APN and the address of the SMF + PGW-C to the UDM + HSS for storage.

The UE stores the corresponding relationship between the PDU session and the APN, and the specific storage may be: the corresponding relation between the S-NSSAI, the DNN and the APN, or the corresponding relation between the PDU session identification and the APN.

And when the UE enters the 4G communication system, the UE determines the APN corresponding to the PDU session to be transferred.

Without the N26 scenario, a PDN connection establishment request is initiated using this APN.

Optionally, in the above procedure, the SMF + PGW-C may further determine an APN-AMBR corresponding to the APN, and the SMF + PGW-C sends the APN-AMBR to the UE.

The APN-AMBR is obtained by the SMF + PGW-C according to the session-AMBR of the UE at 5G. Specifically, the session-AMBR of all PDU sessions using DNN and S-NSSAI corresponding to the first APN is added. Or obtaining the subscription information of the APN corresponding to the DNN of the UE one by one.

The realization idea 2 is as follows: the UE provides the APN to SMF + PGW-C.

When the UE establishes the PDU session in the 5G, the UE sends the APN corresponding to the PDU session to the SMF + PGW-C through the PCO, and the specific way for the UE to acquire the APN corresponding to the PDU session comprises the following steps:

the UE determines the APN corresponding to the S-NSSAI and DNN according to the URSP, or,

the UE generates, based on the locally stored information, or,

the UE generates the information dynamically and generates it,

in another implementation, the SMF + PGW-C sends the corresponding relation between the APN and the SMF + PGW-C to the UDM + HSS for storage.

No N26 scenario: and the UE initiates a PDN connection establishment request by using the APN.

Based on the above idea, the session establishment method and the session transfer method provided by the second solution are described below by two specific examples.

Fig. 10 is a flowchart illustrating an example of a session establishment method and a session transfer method provided in an embodiment of the present application, and as shown in fig. 10, specific implementation steps of the session establishment method and the session transfer method include:

s701: the UE sends a PDU session setup request to the AMF.

In this step, the UE initiates a PDU session setup request in 5G, where the request carries a PDU session identifier, S-NSSAI and DNN. Wherein, the S-NSSAI (Single Network Slice Selection Assistance Information) is used to inform the Network in which Slice the UE establishes the PDU session.

S702: AMF selects SMF + PGW-C according to S-NSSAI and DNN, and sends a PDU session creation SM context (Nsmf _ PDSUSsion _ CreatesContext Request) Request to SMF + PGW-C. The PDU session establishment request carried in step 701 is carried in the message.

In this step, the AMF selects SMF + PGW-C according to the S-NSSAI and DNN, and sends a PDU session creation SM context request to the SMF + PGW-C, wherein the request carries a PDU session identifier, the S-NSSAI and the DNN.

S703: and the SMF + PGW-C requests the subscription information corresponding to the DNN from the UDM + HSS. This step is an optional step.

S704: the SMF + PGW-C obtains the first APN according to the S-NSSAI and DNN of the UE.

In this step, the SMF + PGW-C obtains the first APN according to the S-NSSAI and DNN of the UE, and the APN may be a first APN dynamically generated by the SMF + PGW-C. Specifically, the SMF + PGW-C generates the first APN according to the S-NSSAI and the DNN, or according to the PDU session identifier.

The first APN can also be an APN obtained by the SMF + PGW-C according to a locally stored corresponding relation. In a specific implementation manner, the SMF + PGW-C obtains the first APN according to the correspondence between the S-NSSAI, the DNN, and the APN.

S705: the SMF + PGW-C returns a PDU session creation SM context response to the AMF.

S706: the AMF returns a PDU session establishment acceptance to the UE.

In the above step, the SMF + PGW-C sends the first APN to the UE through the AMF, so that the UE performs PDN connection establishment according to the first APN.

In a specific implementation of the scheme, the SMF + PGW-C may further determine an APN-AMBR corresponding to the first APN, where the APN-AMBR is obtained by the SMF + PGW-C according to the session-AMBR of the UE at 5G. Specifically, the result is obtained by adding session-AMBRs of all PDU sessions (sessions) using DNN and S-NSSAI corresponding to the first APN. Or the SMF + PGW-C obtains the APN-AMBR according to the subscription information of the APN of the UE, which corresponds to the DNN one by one. Then the SMF + PGW-C sends the APN-AMBR to the UE so that the UE can carry out power control according to the APN-AMBR.

S707, the UE saves the corresponding relation between the PDU session and the first APN.

In this step, the UE stores the correspondence between the PDU session and the first APN. Specifically, the UE stores a corresponding relationship between the first APN and the DNN and the S-NSSAI, or a corresponding relationship between the first APN and the PDU session identifier.

Optionally, if the SMF + PGW-C sends the APN-AMBR corresponding to the first APN to the UE, the UE further stores the APN-AMBR.

S708: and the SMF + PGW-C sends the corresponding relation between the SMF + PGW-C address and the first APN to the UDM + HSS.

In the step, the SMF + PGW-C sends the corresponding relation between the SMF + PGW-C address and the first APN to the UDM + HSS, so that the UDM + HSS stores the corresponding relation between the SMF + PGW-C address and the APN.

In this process, optionally, the SMF + PGW-C further sends, to the UDM + HSS, first information used for the UDM + HSS to determine the APN-AMBR of the first APN.

The first information may specifically be:

APN-AMBR determined by SMF + PGW-C; or,

corresponding DNN corresponding to the PDU, and the UDM + HSS obtaining the subscription data of the corresponding second APN according to the DNN; or,

and the UDM acquires subscription data according to the second APN and sets the subscription data as the subscription data of the first APN.

Note: the APN corresponding to DNN is different from the APN corresponding to DNN and S-NSSAI. The APN corresponding to DNN is an APN directly corresponding to DNN one to one.

In the scheme, the method for obtaining the APN-AMBR corresponding to the first APN by the UE comprises the following steps: the SMF + PGW-C is determined at steps S705-S706 and sent to the UE. Or, the SMF + PGW-C is determined and sent to the UDM + HSS, the UDM + HSS is sent to the MME, and the MME sends to the UE through step S714. Or, the UDM + HSS is determined and sent to the MME, and the MME sends to the UE through step S714.

S709: and the UDM + HSS sends the corresponding relation between the SMF + PGW-C ID and the first APN to the MME.

In the step, the UDM + HSS sends the correspondence between the SMF + PGW-C ID and the first APN to the MME, so as to establish a PDN connection in the subsequent step.

Optionally, the UDM + HSS may also send the APN-AMBR to the SMF + PGW-C.

Further, the UDM + HSS sends subscription data for the first APN to the MME.

S710: and the UE determines to move a PDU session to the 4G communication system, and the UE determines the APN corresponding to the PDU session according to the corresponding relation stored in S707.

S711: and the UE sends a PDN connection establishment request to the MME.

S712: and the MME acquires the address of the SMF + PGW-C according to the corresponding relation between the APN and the SMF + PGW-C, and sends a session creating request to the SMF + PGW-C.

S713: and the SMF + PGW-C replies a create session response to the MME.

S714: and the MME returns a PDN connection establishment response to the UE.

In the above steps, the UE determines to move a PDU session to 4G, and then the UE determines the APN corresponding to the PDU session according to the correspondence stored in step S307, and then the UE sends a PDN connection establishment request to the MME, where the request carries a handover indication and the APN obtained in step S710. The MME obtains the address of the SMF + PGW-C according to the corresponding relation between the APN and the SMF + PGW-C obtained in the step S709, sends a request for creating the session to the SMF + PGW-C, carries a handover indication and the APN in the request, replies a response for creating the session to the MME by the SMF + PGW-C, and replies a PDN connection establishment response to the UE by the MME to complete PDN session establishment, namely, the PDU session of the UE is transferred to the 4G communication system.

In the session establishment method and the session transfer method provided by this embodiment, during the PDU session establishment process, the SMF + PGW-C obtains the APN corresponding to the created PDU session and sends the APN to the UE, and the UE locally stores the correspondence between the PDU session and the APN, and during the UE moving from the 5G communication system to the 4G communication system, the UE may determine the APN corresponding to the PDU session to be transferred, thereby implementing selective transfer of the PDU session.

Fig. 11 is a flowchart illustrating another example of a session establishment method and a session transfer method provided in an embodiment of the present application, and as shown in fig. 11, the specific implementation steps of the session establishment method and the session transfer method include:

s801: the UE determines corresponding first APNs of the DNN and the S-NSSAI.

In this step, the UE determines a first APN corresponding to the DNN and the S-NSSAI, and specifically, the UE may obtain the first APN according to a correspondence between the locally stored DNN, S-NSSAI, and APN, or obtain the first APN according to a UE routing Policy (URSP).

The details of the URSP are as follows:

rule priority

Traffic descriptor

-Application identification

-IP descriptors

-Non-IP descriptors

Route selection descriptor

-SSC mode selection

-Network Slice Selection

-DNN selection

-APN

-Non-Seamless off flow indication: whether to offload to non-3GPP

-Access Type Preference 3GPP or non-3GPP

S802: the UE sends a PDU session setup request to the AMF.

S803: and the AMF selects the SMF + PGW-C according to the S-NSSAI and the DNN and sends a PDU session creation SM context request to the SMF + PGW-C.

In the above step, when the UE sends the PDU session establishment request to the SMF + PGW-C through the AMF, the UE may send the first APN to the SMF + PGW-C. Optionally, the first APN may be sent via PCO.

S804: and the SMF + PGW-C requests the subscription information corresponding to the DNN from the UDM + HSS.

S805: the SMF + PGW-C returns a PDU session creation SM context response to the AMF.

S806: the AMF returns a PDU session establishment acceptance to the UE.

The above steps are similar to steps S705-S706 in fig. 10, and are not described again here.

S807: and the SMF + PGW-C sends the corresponding relation between the SMF + PGW-C address and the first APN to the UDM + HSS.

S808: and the UDM sends the corresponding relation between the SMF + PGW-C ID and the first APN to the MME.

The above steps are similar to steps S708-S709 in fig. 10, and are not described again here.

S809: and the UE determines to move a PDU session to the 4G communication system, and the UE determines the APN corresponding to the PDU session according to the corresponding relation stored in S801.

S810: and the UE sends a PDN connection establishment request to the MME.

S811: and the MME acquires the address of the SMF + PGW-C according to the corresponding relation between the APN and the SMF + PGW-C, and sends a session creating request to the SMF + PGW-C.

S812: and the SMF + PGW-C replies a create session response to the MME.

S813: and the MME returns a PDN connection establishment response to the UE.

Different from the foregoing embodiment, in the session establishment process of PDU, the UE determines an APN corresponding to a PDU session to be created, and sends the APN to SMF + PGW-C, the UE locally stores a correspondence between the PDU session and the APN, and in the process of moving the UE from the 5G communication system to the 4G communication system, the UE may determine an APN corresponding to the PDU session to be transferred, so as to implement selective transfer of the PDU session.

Fig. 12 is a flowchart illustrating a third embodiment of a session transfer method according to an embodiment of the present application, and as shown in fig. 12, the session transfer method according to this embodiment specifically includes the following steps:

s901: when the UE determines that the PDU session needs to be moved from 5G to 4G, the UE sends a PDN connection request to the MME.

In this step, when the UE enters the 4G communication system from the 5G communication system, the UE determines that the PDU session needs to be transferred from the 5G communication system to the 4G communication system, and the UE may send a PDN connection establishment request to the MME, where the PDN connection establishment request carries an APN corresponding to the PDU session and a PDU session identifier.

In a specific implementation of the scheme, the PDN connection establishment request may carry a transfer instruction, that is, a handover instruction, where the transfer instruction is used to instruct to transfer the PDU session to the 4G communication system.

S902: and the MME determines a first SMF + PGW-C according to the APN and PDU session identification corresponding to the PDU session and the corresponding relation among the APN, the SMF + PGW-C and the PDU session identification obtained from the UDM + HSS.

In this step, in the PDU session creation process of the UE, or before this step, the MME receives the correspondence between the APN, SMF + PGW-C and the PDU session identifier sent by the UDM + HSS. And the MME stores the corresponding relation, and selects a first SMF + PGW-C according to the APN and PDU session identification and the corresponding relation after receiving the APN and PDU session identification sent by the UE.

S903: and the MME sends a session creating request to the first SMF + PGW-C.

S904: and the MME receives a session creation response returned by the first SMF + PGW-C.

S905: and the UE receives the PDN connection response returned by the MME.

In the process, after selecting a first SMF + PGW-C, the MME sends a request for creating a session carrying an APN to the first SMF + PGW-C, the first SMF + PGW-C detects whether the PDU session exists according to a PDU session identifier in the request for creating a session, if so, determines to transfer the PDU session to the 4G communication system, creates the session, and returns a response for creating the session to the MME, and the MME returns a response for PDN connection to the UE according to the received response for creating the session, that is, completes PDN connection establishment, and transfers the PDU session to the 4G communication system.

Fig. 13 is a flowchart illustrating a fourth embodiment of the session transfer method according to the embodiment of the present application, and as shown in fig. 13, the session transfer method according to the embodiment specifically includes the following steps:

s1001: when the UE determines that the PDU session needs to be moved from 5G to 4G, the UE sends a PDN connection request to the MME.

S1002: and the MME selects a first SMF + PGW-C from at least one SMF + PGW-C corresponding to the APN according to the APN corresponding to the PDU session.

S1003: and the MME sends a session creating request to the first SMF + PGW-C.

The foregoing steps are similar to steps S901-S903 in the embodiment shown in fig. 12, and are not described again here.

S1004: and the MME receives a creating session rejection response returned by the first SMF + PGW-C.

In this step, after selecting a first SMF + PGW-C, the MME sends a create session request carrying an APN to the first SMF + PGW-C, where the first SMF + PGW-C detects whether there is a PDU session according to a PDU session identifier in the create session request, and if there is no PDU session, determines to reject the session create request, and returns a session reject response to the MME, where optionally, the session reject response may carry a rejected reason, for example: there is no PDU session corresponding to the PDU session identification.

S1005: and the MME selects any second SMF + PGW-C except the first SMF + PGW-C from at least one SMF + PGW-C corresponding to the APN to initiate session creation, and repeats the step until the session creation is completed, and the MME returns a PDN connection response to the UE.

In this step, the MME selects a second SMF + PGW-C from the remaining SMF + PGW-cs to initiate session creation according to the received session rejection response until the session creation is completed, and returns a PDN connection response to the UE, that is, completes PDN connection establishment, and transfers the PDU session to the 4G communication system.

Fig. 14 is a flowchart of a fifth embodiment of the session transfer method provided in the embodiment of the present application, and as shown in fig. 5, the session transfer method provided in this embodiment is applied to SMF + PGW-C, and specifically includes the following steps:

s1101: the SMF + PGW-C receives a session creating request sent by the MME, and the session creating request carries a transfer indication, a PDU session identifier and an APN.

S1102: and the SMF + PGW-C detects whether a PDU session corresponding to the PDU session identification exists or not according to the PDU session identification.

S1103: if not, returning a created session rejection response to the MME, wherein the created session rejection response indicates the reason for rejection.

S1104: and if so, completing the session creation according to the session creation request, and sending a session creation response to the MME.

In the above step, the SMF + PGW-C detects whether the PDU session exists according to the PDU session identifier in the session creation request, and if so, determines to transfer the PDU session to the 4G communication system, performs session creation, and returns a session creation response to the MME; and if the SMF + PGW-C does not exist, determining to reject the session creation request, and returning a session rejection response to the MME so that the MME reselects another SMF + PGW-C for session transfer.

Based on the above embodiments, the main idea of the third solution is as follows: still, DNN is in one-to-one correspondence with APN, and PDU sessions of multiple slices corresponding to DNN can be transferred to 4G.

The realization idea 1:

and in the PDU session establishment process of the UE, the SMF + PGW-C sends the corresponding relation of the APN, the PDU session identification and the SMF + PGW-C to the UDM + HSS.

When the UE enters 4G and the UE determines that PDU session transfer is needed, a PDN connection establishment request carrying a PDU session identifier and an APN is sent to the MME in the 4G, and the MME selects the SMF + PGW-C to establish the session according to the corresponding relation between the APN, the PDU session identifier and the SMF + PGW-C obtained from the UDM + HSS, so that PDN connection is completed.

The realization idea 2 is as follows:

the MME selects one of a plurality of SMF + PGW-C corresponding to 1 DNN to initiate the session creation;

and if the SMF + PGW-C returns failure, the MME selects another SMF + PGW-C and initiates session creation until the PDU session is transferred to the 4G communication system.

Fig. 15 is a flowchart illustrating another example of a session establishing method and a session transferring method provided in the embodiment of the present application, and as shown in fig. 15, the session establishing method and the session transferring method are specifically implemented by the following steps:

s1201: the UE sends a PDU session setup request to the AMF.

In this step, the UE initiates a PDU session setup request in 5G, where the request carries a PDU session identifier, S-NSSAI and DNN.

S1202: and the AMF selects the SMF + PGW-C according to the S-NSSAI and the DNN and sends a PDU session creation SM context request to the SMF + PGW-C.

In this step, the AMF selects SMF + PGW-C according to the S-NSSAI and the DNN, and sends a request to the SMF + PGW-C, wherein the request carries the PDU session identifier, the S-NSSAI and the DNN.

S1203: and the SMF + PGW-C requests the subscription information corresponding to the DNN from the UDM + HSS. This step is an optional step.

S1204: the SMF + PGW-C returns a PDU session creation SM context response to the AMF.

S1205: the AMF returns a PDU session establishment response to the UE.

In the above step, the SMF + PGW-C sends a PDU session setup response message to the UE through the AMF.

S1206: and the SMF + PGW-C sends the corresponding relation of the SMF + PGW-C address, the DNN and the PDU session identifier to the UDM + HSS.

S1207: and the UDM + HSS sends the SMF + PGW-C address and the corresponding relation between the APN and the PDU session identifier to the MME.

S1208, the UE determines to move a PDU session to the 4G communication system, and the UE determines the APN corresponding to the PDU session and the PDU session identification.

In this step, the UE determines to move a PDU session to 4G, and the UE determines the APN and the PDU session identifier corresponding to the PDU session.

S1209: and the UE sends a PDN connection establishment request carrying APN and PDU session identification to the MME.

S1210: and the MME selects the SMF + PGW-C according to the PDU session identifier and the APN.

S1211: and the MME sends a session creating request to the SMF + PGW-C.

S1212: and the SMF + PGW-C replies a create session response to the MME.

S1213: and the MME returns a PDN connection establishment response to the UE.

In the above steps, the UE determines to send a PDN connection establishment request to the MME, where the request carries an APN and a PDU session identity. And the MME selects the SMF + PGW-C according to the obtained corresponding relation between the APN and the SMF + PGW-C, sends a session creating request to the SMF + PGW-C, carries the APN, replies a session creating response to the MME from the SMF + PGW-C, replies a PDN connection creating response to the UE from the MME, completes PDN session creation, and transfers the PDU session of the UE to the 4G communication system.

Fig. 16 is a flowchart illustrating a further example of the session establishing method and the session transferring method provided in the embodiment of the present application, and as shown in fig. 16, the specific implementation steps of the session establishing method and the session transferring method are as follows:

s1301: and the UE sends a PDN connection establishment request to the MME.

In this step, the UE initiates a PDN connection establishment request in 4G, carrying a handover indication, an APN, and a PDU session ID.

S1302: the MME selects one SMF + PGW-C-1 from a plurality of SMF + PGW-Cs according to the APN.

S1303: and the MME initiates a session creation request to the selected SMF + PGW-C-1.

In the above step, the MME selects one from a plurality of SMF + PGW-C according to the APN, and initiates a session creation request to the selected SMF + PGW-C.

And S1304, the SMF + PGW-C-1 detects whether a PDU session exists according to the PDU session identification in the PCO.

S1305: and if not, the SMF + PGW-C-1 returns a session creation rejection to the MME.

In this step, the SMF + PGW-C detects whether there is a PDU session according to the PDU session identifier in the PCO, and if not, rejects and carries a cause value, for example, there is no PDU session.

S1306: and the MME selects other SMF + PGW-C-2 to create the session according to the reason for creating the session rejection.

The MME selects other SMF + PGW-C, i.e., SMF + PGW-C-2, according to reject cause.

S1307: the MME sends a create session request to SMF + PGW-C-2.

S1308: SMF + PGW-C-2 replies a create session response to the MME.

S1309: and the MME returns a PDN connection establishment response to the UE.

In the above steps, if the SMF + PGW-C determines that the PDU session exists according to the PCO, the subsequent PDN connection establishment procedure is completed, and PDU session transfer is completed.

Fig. 17 is a schematic structural diagram of a first embodiment of a UE according to an embodiment of the present application, and as shown in fig. 17, the UE 10 includes a sending module 11, a processing module 12, and a receiving module 13.

In a specific implementation of the UE, the sending module 11 is configured to send a first message to the access node and the AMF, where the first message is used to establish a PDU session; the first message comprises a PDU session establishment request and priority information, wherein the priority information is used for indicating the priority of transferring the PDU session which is requested to be established by the UE to a 4G communication system;

a receiving module 13, configured to receive a second message sent by the AMF, where the second message includes a PDU session establishment accept.

Optionally, the UE further includes:

a processing module 12, configured to determine the priority information according to a combination of one or more of the following:

the PDU session corresponds to S-NSSAI;

an application using the PDU session;

URSP saved by the UE;

Optionally, the processing module 12 is configured to determine, when the UE moves from the 5G communication system to the 4G communication system, a first PDU session to be transferred to the 4G communication system according to the priority information of each PDU session corresponding to the used DNN.

Optionally, the processing module 12 is specifically configured to:

The UE provided by each implementation manner is configured to execute the technical solution on the UE side in any of the foregoing method embodiments, and the implementation principle and the technical effect are similar, which are not described herein again.

Fig. 18 is a schematic structural diagram of a first embodiment of an AMF provided in this application, and as shown in fig. 18, the AMF 20 includes a sending module 21, a processing module 22, and a receiving module 23.

In a specific implementation of the AMF, the sending module 21 is configured to send, to an MME, information of a PDN connection corresponding to a first PDU session when a UE moves from a 5G communication system to a 4G communication system, where the information of the PDN connection is used for the MME to establish a PDN connection for the UE;

Optionally, the AMF further includes: a receiving module 23, configured to:

Optionally, the receiving module 23 is specifically configured to:

Optionally, the AMF further includes: a processing module 22;

the receiving module 23 is further configured to receive an EBI allocation request sent by the first SMF + PGW-C;

the processing module 22 is specifically configured to:

or,

the processing module 22 is specifically configured to:

or,

the processing module 22 is specifically configured to:

or,

the processing module 22 is specifically configured to:

Optionally, the EBI allocation request includes an identifier of the first PDU session, and the processing module 23 is further configured to determine a first DNN corresponding to the first PDU session according to the identifier of the first PDU session.

Optionally, the processing module 22 is further configured to:

or,

and acquiring the corresponding priority of each SMF + PGW-C.

Optionally, the sending module 21 is further configured to send, to the MME, information of a PDN connection corresponding to a fourth PDU session, where the fourth PDU session and the first PDU session use the same DNN and SMF + PGW-C.

Optionally, the AMF further includes: a processing module 22;

the processing module 22 is configured to obtain the first PDU session with the highest priority in the PDU sessions corresponding to the first DNN;

the sending module 21 is further configured to request, to a first SMF + PGW-C corresponding to the first PDU session, information of the PDN connection corresponding to the first PDU session;

or,

the sending module 21 is further configured to request, to a first SMF + PGW-C corresponding to the first PDU session, information of the PDN connection corresponding to the first PDU session, and acquire information of PDN connections corresponding to other PDU sessions using the first DNN.

Optionally, the receiving module 23 is specifically configured to:

Optionally, the priority information sent by the UE and received by the receiving module 23 includes:

the priority of the S-NSSAI corresponding to the PDU session; or,

the priority of S-NSSAI and DNN corresponding to the PDU session; or,

a priority of an application using the PDU session.

The AMF provided by each implementation manner is used for executing the technical scheme on the AMF side in any one of the foregoing method embodiments, and the implementation principle and the technical effect are similar and are not described herein again.

Fig. 19 is a schematic structural diagram of a first embodiment of the SMF + PGW-C provided in the embodiment of the present application, and as shown in fig. 19, the SMF + PGW-C30 includes a processing module 31, a transmitting module 32, and a receiving module 33.

In a specific implementation of this SMF + PGW-C30:

a processing module 31, configured to acquire priority information of a PDU session transfer of a UE to a 4G communication system in a PDU session establishment process of the UE;

a sending module 32, configured to send the priority information to the UDM + HSS or the AMF.

Optionally, the SMF + PGW-C further includes: a receiving module 33;

or,

The SMF + PGW-C provided by each implementation manner is used for executing the technical scheme on the SMF + PGW-C side in any one of the foregoing method embodiments, and the implementation principle and the technical effect are similar, and are not described herein again.

Fig. 20 is a schematic structural diagram of a UDM + HSS according to a first embodiment of the present disclosure, and as shown in fig. 20, the UDM + HSS 40 includes a storage module 41, a processing module 42, a sending module 43, and a receiving module 44.

In a specific implementation of this UDM + HSS 40:

a storage module 41, configured to store a correspondence between addresses and priorities of a DNN, an SMF + PGW-C used by a PDU session of the UE; the priority is used for indicating the priority of transferring the PDU session corresponding to the SMF + PGW-C to the 4G communication system, or the priority is used for indicating the priority of transferring the SMF + PGW-C to the 4G communication system;

a processing module 42, configured to determine, without according to the stored priority, a first SMF + PGW-C address used by the UE in the 4G communication system;

a sending module 43, configured to send the first SMF + PGW-C address and APN to an MME; wherein the APN corresponds to the DNN.

Optionally, the processing module 42 is specifically configured to:

Optionally, the receiving module 44 is configured to receive the DNN, the address of the SMF + PGW-C, and the priority sent by the SMF + PGW-C;

the processing module 42 is further configured to determine whether correspondence between other SMF + PGW-C corresponding to the DNN and the priority is saved;

if so, the processing module 42 is further configured to determine whether the priority corresponding to the SMF + PGW-C is higher than the priority corresponding to the other saved SMF + PGW-C corresponding to the DNN;

if yes, the storage module 41 stores the corresponding relationship between the SMF + PGW-C and the priority.

Optionally, the correspondence between DNN, SMF + PGW-C and priority includes:

corresponding relation of DNN, S-NSSAI, SMF + PGW-C and priority; or,

and the PDU session identification, the SMF + PGW-C and the priority.

The UDM + HSS provided by each implementation manner is used for executing the technical scheme at the UDM + HSS side in any method embodiment, and the implementation principle and the technical effect are similar, and are not described herein again.

Fig. 21 is a schematic structural diagram of a second embodiment of the UDM + HSS provided in the present application, and as shown in fig. 21, the UDM + HSS 50 includes a storage module 51, a processing module 52, a sending module 53, and a receiving module 54.

In a specific implementation of this UDM + HSS 50:

a storage module 51, configured to store a correspondence between addresses and priorities of an APN, an SMF + PGW-C used in a PDU session transfer of a UE to a 4G communication system; the priority is used for indicating the priority of transferring the PDU session corresponding to the SMF + PGW-C to the 4G communication system, or the priority is used for indicating the priority of transferring the SMF + PGW-C to the 4G communication system;

a processing module 52, configured to determine, according to the stored priority, a first SMF + PGW-C address used by the UE in the 4G communication system;

a sending module 53, configured to send the first SMF + PGW-C address and the APN corresponding to the first SMF + PGW-C address to an MME.

Optionally, the processing module 52 is specifically configured to determine, according to the corresponding relationship, an address of an SMF + PGW-C with a highest priority in the stored SMF + PGW-cs as the first SMF + PGW-C address.

Optionally, the UDM + HSS further includes:

a receiving module 54, configured to receive the APN, the address of the SMF + PGW-C, and the priority sent by the SMF + PGW-C;

the processing module 52 is configured to determine whether a correspondence between other SMF + PGW-C corresponding to the DNN corresponding to the APN and the priority is locally stored;

if so, the processing module 52 is further configured to determine whether the priority corresponding to the SMF + PGW-C is higher than the priority corresponding to the other saved SMF + PGW-C corresponding to the DNN;

if yes, the storage module 51 stores the corresponding relationship between the SMF + PGW-C and the priority.

corresponding relation of DNN, S-NSSAI, SMF + PGW-C and priority; or,

and the PDU session identification, the SMF + PGW-C and the priority.

Fig. 22 is a schematic structural diagram of a second UE embodiment provided in the embodiment of the present application, and as shown in fig. 22, the UE 60 includes a processing module 61, a transmitting module 62, and a receiving module 63.

In a specific implementation of the UE 60:

the processing module 61 is configured to, when it is determined that a first PDU session is transferred to a 4G communication system, acquire a first APN corresponding to the first PDU session;

a sending module 62, configured to send a PDN connection establishment request to the MME; the PDN connection establishment request carries the first APN corresponding to the first PDU session;

a receiving module 63, configured to receive a PDN connection establishment acceptance sent by the MME, so as to establish the PDN connection.

Optionally, the processing module 61 is specifically configured to:

Optionally, the correspondence between the PDU session and the APN includes:

or,

and the PDU session identification of the PDU session corresponds to the APN.

Optionally, the receiving module 63 is further configured to receive, in the process of establishing the first PDU session, a first APN, which is sent by the SMF + PGW-C and corresponds to the first PDU session;

the processing module 61 is further configured to obtain and store a corresponding relationship between the first PDU session and the first APN in a storage device.

Optionally, the processing module 61 is specifically configured to:

or,

generating the first APN corresponding to the S-NSSAI and DNN of the first PDU.

Optionally, the receiving module 63 is further configured to receive a first APN-AMBR, which is sent by the SMF + PGW-C and corresponds to the first PDU session.

Fig. 23 is a schematic structural diagram of a second embodiment of the SMF + PGW-C provided in the embodiment of the present application, and as shown in fig. 23, the SMF + PGW-C70 includes: a receiving module 71, a processing module 72, and a transmitting module 73.

In a specific implementation of this SMF + PGW-C70:

a receiving module 71, configured to receive a PDU session establishment request sent by a UE;

a processing module 72, configured to acquire an APN corresponding to the PDU session requested to be established by the UE;

a sending module 73, configured to send the APN and the address of SMF + PGW-C to UDM + HSS;

the sending module 73 is further configured to send a PDU session establishment acceptance to the UE, and complete the PDU session establishment process.

Optionally, the PDU session establishment request includes S-NSSAI and DNN, and the processing module 72 is specifically configured to:

and acquiring APNs corresponding to the S-NSSAI and the DNN.

Optionally, the processing module 72 is specifically configured to:

Or,

Optionally, the PDU session establishment request includes the APN, and the processing module 72 is further configured to obtain the APN from the PDU session establishment request.

Optionally, the PDU session establishment accept includes the APN.

Optionally, the processing module 72 is further configured to obtain an APN-AMBR corresponding to the APN.

Optionally, the sending module 73 is further configured to:

sending the APN-AMBR corresponding to the APN to the UE;

and/or the presence of a gas in the gas,

and sending the APN-AMBR corresponding to the APN to the UDM + HSS.

Optionally, the processing module 72 is specifically configured to:

or,

Optionally, the processing module 72 is specifically configured to:

Optionally, the sending module 73 is further configured to send first information to a UDM + HSS, where the first information is used for the UDM + HSS to determine an APN-AMBR corresponding to the APN.

Optionally, the first information includes:

the APN-AMBR which is determined by the SMF + PGW-C and corresponds to the APN;

or,

DNN corresponding to the PDU session;

or,

and the APN corresponding to the DNN corresponding to the PDU session.

Fig. 24 is a schematic structural diagram of a third embodiment of a UE provided in the embodiment of the present application, and as shown in fig. 24, the UE 80 includes a sending module 81 and a receiving module 82.

In a specific implementation of the UE 80:

a sending module 81, configured to send a PDN connection request to the MME when it is determined that the PDU session needs to be moved from 5G to 4G; the PDN connection request carries the APN corresponding to the PDU session and a PDU session identifier;

a receiving module 82, configured to receive a PDN connection response returned by the MME.

Fig. 25 is a schematic structural diagram of a first MME according to an embodiment of the present application, and as shown in fig. 25, the MME 90 includes a receiving module 91, a processing module 92, and a sending module 93.

In a specific implementation of the MME:

a receiving module 91, configured to receive a PDN connection request sent by a UE; the PDN connection request carries the APN corresponding to the PDU session and a PDU session identifier;

a processing module 92, configured to determine the first SMF + PGW-C according to the APN and the PDU session identifier corresponding to the PDU session, and a correspondence between the APN, the SMF + PGW-C, and the PDU session identifier obtained from the UDM + HSS;

a sending module 93, configured to send a session creation request to the first SMF + PGW-C;

the receiving module 91 is further configured to receive a session creation response returned by the first SMF + PGW-C;

the sending module 93 is further configured to return a PDN connection response to the UE according to the create session response.

Optionally, the receiving module 91 is further configured to receive a correspondence between an APN, an SMF + PGW-C and a PDU session identifier sent by the UDM + HSS.

The MME provided in each implementation manner is configured to execute the technical scheme on the MME side in any method embodiment, and the implementation principle and the technical effect are similar, which are not described herein again.

Fig. 26 is a schematic structural diagram of a second MME embodiment provided in the embodiment of the present application, and as shown in fig. 26, the MME 100 includes a receiving module 101, a processing module 102, and a sending module 103.

In a specific implementation of the MME:

a receiving module 101, configured to receive a PDN connection request sent by a UE; the PDN connection request carries a transfer instruction, an APN corresponding to the PDU session and a PDU session identifier, wherein the transfer instruction is used for instructing the PDU session to be transferred to a 4G network;

a processing module 102, configured to select, according to an APN corresponding to the PDU session, a first SMF + PGW-C from at least one SMF + PGW-C corresponding to the APN;

a sending module 103, configured to send a session creation request to the first SMF + PGW-C;

if the receiving module 101 receives a session creation rejection response returned by the first SMF + PGW-C; the created session rejection response carries the rejected reason, the processing module selects any one of the second SMF + PGW-cs except the first SMF + PGW-C from at least one SMF + PGW-C corresponding to the APN to initiate session creation, and the sending module 103 returns a PDN connection response to the UE after the session creation is completed.

Fig. 27 is a schematic structural diagram of a third embodiment of the SMF + PGW-C provided in the embodiment of the present application, and as shown in fig. 27, the SMF + PGW-C110 includes: a receiving module 111, a processing module 112 and a transmitting module 113.

A receiving module 111, configured to receive a session creation request sent by an MME, where the session creation request carries a transfer indication, a PDU session identifier, and an APN;

a processing module 112, configured to detect whether a PDU session corresponding to the PDU session identifier exists according to the PDU session identifier;

a sending module 113, configured to return a create session rejection response to the MME if the processing module detects that the request is negative, where the create session rejection response indicates a reject reason;

the processing module 112 is further configured to complete a session creation according to the session creation request if the session is established;

the sending module 113 is further configured to send a create session response to the MME.

Physical device

Fig. 28 is a schematic structural diagram of a UE according to a fourth embodiment of the present application, and as shown in fig. 28, the UE at least includes: a transmitter for transmitting a message, a receiver for receiving a message, a memory, and a processor.

Alternatively, the receiver and transmitter may be implemented by a transceiver

In the specific implementation of the UE:

Optionally, the UE further includes:

the PDU session corresponds to S-NSSAI;

an application using the PDU session;

URSP saved by the UE;

Optionally, the processor is specifically configured to:

Fig. 29 is a schematic structural diagram of a second embodiment of an AMF provided in an embodiment of the present application, and as shown in fig. 29, the AMF at least includes: a transmitter for transmitting a message, a receiver for receiving a message, a memory, and a processor.

In the specific implementation of the AMF:

Optionally, the AMF further includes: a receiver for:

Optionally, the receiver is specifically configured to:

Optionally, the AMF further includes: a processor;

the processor is specifically configured to:

or,

the processor is specifically configured to:

or,

the processor is specifically configured to:

or,

the processor is specifically configured to:

Optionally, the processor is further configured to:

or,

and acquiring the corresponding priority of each SMF + PGW-C.

Optionally, the AMF further includes: a processor;

or,

Optionally, the receiver is specifically configured to:

the priority of the S-NSSAI corresponding to the PDU session; or,

the priority of S-NSSAI and DNN corresponding to the PDU session; or,

a priority of an application using the PDU session.

Fig. 30 is a schematic structural diagram of a fourth embodiment of the SMF + PGW-C provided in the embodiment of the present application, and as shown in fig. 30, the SMF + PGW-C at least includes: a transmitter for transmitting a message, a receiver for receiving a message, a memory, and a processor.

The specific implementation of the SMF + PGW-C is as follows:

Optionally, the SMF + PGW-C further includes: a receiver;

or,

Fig. 31 is a schematic structural diagram of a third embodiment of the UDM + HSS provided in the embodiment of the present application, and as shown in fig. 31, the UDM + HSS at least includes: a transmitter for transmitting a message, a receiver for receiving a message, a memory, and a processor.

In the specific implementation of the UDM + HSS:

Optionally, the processor is specifically configured to:

Optionally, the UDM + HSS further comprises: a receiver;

Optionally, the correspondence between DNN, SMF + PGW-C and priority includes:

corresponding relation of DNN, S-NSSAI, SMF + PGW-C and priority; or,

and the PDU session identification, the SMF + PGW-C and the priority.

Fig. 32 is a schematic structural diagram of a fourth embodiment of the UDM + HSS provided in the embodiment of the present application, and as shown in fig. 32, the UDM + HSS at least includes: a transmitter for transmitting a message, a receiver for receiving a message, a memory, and a processor.

In the specific implementation of the UDM + HSS:

Optionally, the UDM + HSS further includes:

corresponding relation of DNN, S-NSSAI, SMF + PGW-C and priority; or,

and the PDU session identification, the SMF + PGW-C and the priority.

Fig. 33 is a schematic structural diagram of a UE according to a fifth embodiment of the present application, where the UE at least includes: a transmitter for transmitting a message, a receiver for receiving a message, a memory, and a processor.

In the specific implementation of the UE:

Optionally, the processor is specifically configured to:

Optionally, the correspondence between the PDU session and the APN includes:

or,

and the PDU session identification of the PDU session corresponds to the APN.

Optionally, the processor is specifically configured to:

or,

generating the first APN corresponding to the S-NSSAI and DNN of the first PDU.

Fig. 34 is a schematic structural diagram of a fifth embodiment of the SMF + PGW-C provided in the embodiment of the present application, and as shown in fig. 34, the SMF + PGW-C at least includes: a transmitter for transmitting a message, a receiver for receiving a message, a memory, and a processor.

The specific implementation of the SMF + PGW-C is as follows:

and acquiring APNs corresponding to the S-NSSAI and the DNN.

Optionally, the processor is specifically configured to:

Or,

Optionally, the PDU session establishment accept includes the APN.

Optionally, the transmitter is further configured to:

sending the APN-AMBR corresponding to the APN to the UE;

and/or the presence of a gas in the gas,

and sending the APN-AMBR corresponding to the APN to the UDM + HSS.

Optionally, the processor is specifically configured to:

or,

Optionally, the processor is specifically configured to:

Optionally, the first information includes:

the APN-AMBR which is determined by the SMF + PGW-C and corresponds to the APN;

or,

DNN corresponding to the PDU session;

or,

and the APN corresponding to the DNN corresponding to the PDU session.

Fig. 35 is a schematic structural diagram of a UE according to a sixth embodiment of the present application, and as shown in fig. 35, the UE at least includes: a transmitter for transmitting a message, a receiver for receiving a message, a memory, and a processor.

In the specific implementation of the UE:

Fig. 36 is a schematic structural diagram of a third MME embodiment provided in the embodiment of the present application, and as shown in fig. 25, the MME 90 at least includes: a transmitter for transmitting a message, a receiver for receiving a message, a memory, and a processor.

In the specific implementation of the MME:

Fig. 37 is a schematic structural diagram of a fourth MME according to an embodiment of the present application, and as shown in fig. 26, the MME includes: a transmitter for transmitting a message, a receiver for receiving a message, a memory, and a processor.

In the specific implementation of the MME:

Fig. 38 is a schematic structural diagram of a sixth embodiment of an SMF + PGW-C provided in the embodiment of the present application, and as shown in fig. 38, the SMF + PGW-C includes: a transmitter for transmitting a message, a receiver for receiving a message, a memory, and a processor.

The specific implementation of the SMF + PGW-C is as follows:

In the above-mentioned specific implementation of the UE or each network device, the number of the processors is at least one, and the processors are used for executing execution instructions stored in the memory, that is, computer programs. Optionally, the memory may also be integrated within the processor. Alternatively, the receiver and the transmitter may be implemented by a transceiver, which is not limited in this embodiment.

The present application also provides a storage medium for storing a computer program for implementing the session establishment method or the session transfer method on the UE side in the foregoing method embodiments.

The present application also provides a storage medium for storing a computer program for implementing a session establishment method or a session transfer method on the AMF side in the method embodiment.

The present application further provides a storage medium, where the storage medium is used to store a computer program, and the computer program is used to implement a session establishment method or a session transfer method on the SMF + PGW-C side in the method embodiment.

The present application also provides a storage medium for storing a computer program for implementing a session establishment method or a session transfer method on the UDM + HSS side in the method embodiment.

The present application also provides a storage medium, where the storage medium is used to store a computer program, and the computer program is used to implement the session transfer method on the MME side in the foregoing method embodiment.

In the above-mentioned Specific implementation of the UE or each network-side device, it should be understood that the Processor may be a Central Processing Unit (CPU), or may also be other general-purpose processors, Digital Signal Processors (DSP), Application Specific Integrated Circuits (ASIC), etc. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like. The steps of a method disclosed in connection with the present application may be embodied directly in a hardware processor, or in a combination of the hardware and software modules in the processor.

All or a portion of the steps of implementing the above-described method embodiments may be performed by hardware associated with program instructions. The aforementioned program may be stored in a readable memory. When executed, the program performs steps comprising the method embodiments described above; and the aforementioned memory (storage medium) includes: read-only memory (ROM), RAM, flash memory, hard disk, solid state disk, magnetic tape (magnetic tape), floppy disk (flexible disk), optical disk (optical disk), and any combination thereof.

Claims

1. A method for session establishment, the method comprising:

user Equipment (UE) sends a first message to an access and mobility management function (AMF), wherein the first message is used for establishing a Protocol Data Unit (PDU) session; the first message comprises a PDU session establishment request and priority information, wherein the priority information is used for indicating the priority of transferring the PDU session which is requested to be established by the UE to a 4G communication system;

2. The method of claim 1, further comprising:

selecting auxiliary information S-NSSAI for a single network slice corresponding to the PDU session;

an application using the PDU session;

a UE routing strategy URSP stored by the UE;

3. The method of claim 1 or 2, wherein the second message further comprises:

priority information of the PDU session determined by a network.

4. The method according to claim 1 or 2, characterized in that the method further comprises:

when the UE moves from the 5G communication system to the 4G communication system, the UE determines a first PDU session transferred to the 4G communication system according to the priority information of each PDU session corresponding to the used data network name DNN.

5. The method of claim 4, wherein the UE determining a first PDU session to transfer to the 4G communication system based on the priority information for each PDU session for the DNN used comprises:

6. A method of session transfer, the method comprising:

when User Equipment (UE) moves from a 5G communication system to a 4G communication system, an access and mobility management function (AMF) sends information of a Protocol Data Network (PDN) connection corresponding to a first Protocol Data Unit (PDU) session to a Mobility Management Entity (MME), wherein the information of the PDN connection is used for the MME to establish the PDN connection for the UE;

the first PDU session is a PDU session with the highest priority transferred to a 4G communication system in a plurality of PDU sessions established by the UE and using a first data network name DNN.

7. The method of claim 6, further comprising:

the AMF receives priority information of the first PDU session, which is sent by a first session management function, a control plane SMF of a protocol data network gateway and a PGW-C;

8. The method of claim 7, wherein the AMF receiving the priority information of the first PDU session sent by a first SMF + PGW-C comprises:

and in an evolved packet system bearer identity (EBI) allocation process, the AMF receives the priority information of the first PDU session sent by the first SMF + PGW-C.

9. The method of claim 8, wherein the receiving, by the AMF, the priority information of the first PDU session sent by the first SMF + PGW-C during an EBI allocation procedure comprises:

the AMF receives an EBI allocation request sent by the first SMF + PGW-C;

or,

the AMF receives an EBI allocation request sent by the first SMF + PGW-C;

or,

the AMF receives an EBI allocation request sent by the first SMF + PGW-C;

or,

the AMF receives an EBI allocation request sent by the first SMF + PGW-C;

10. The method of claim 9, wherein the EBI allocation request contains an identification of the first PDU session, the method comprising:

11. The method of claim 9, further comprising:

the AMF selects the priority of auxiliary information S-NSSAI according to a single network slice corresponding to the stored SMF + PGW-C, and determines the priority corresponding to the first SMF + PGW-C and the priority corresponding to the second SMF + PGW-C;

or,

and the AMF acquires the corresponding priority of each SMF + PGW-C.

12. The method according to any one of claims 6 to 11, further comprising:

13. The method according to any one of claims 6 to 11, further comprising:

or,

14. The method of claim 8, wherein the AMF receiving the priority information of the first PDU session sent by the first SMF + PGW-C comprises:

15. The method according to claim 7, wherein the priority information received by the AMF and sent by the UE comprises:

the priority of the S-NSSAI corresponding to the PDU session; or,

the priority of S-NSSAI and DNN corresponding to the PDU session; or,

a priority of an application using the PDU session.

16. A method for session establishment, the method comprising:

a session management function + a control plane SMF + PGW-C of a protocol data network gateway (PDN-GW) acquires priority information of a Protocol Data Unit (PDU) session transfer of User Equipment (UE) to a 4G communication system in a PDU session establishment process of the UE;

and the SMF + PGW-C sends the priority information to a unified data management + home subscription server UDM + HSS or an access and mobility management function AMF.

17. The method of claim 16,

the priority information is the priority of the received PDU session transferred to the 4G communication system sent by the UE;

or,

the priority information is the priority of the PDU session transfer to the 4G communication system, which is determined by the SMF + PGW-C according to the single network slice selection auxiliary information S-NSSAI of the PDU session;

or,

18. A method of session transfer, the method comprising:

the method comprises the steps that the corresponding relation between a data network name DNN used by a protocol data unit PDU session of user equipment UE, a session management function and the address and the priority of a control plane SMF + PGW-C of a protocol data network gateway is stored by a unified data management + home subscription server UDM + HSS; the priority is used for indicating the priority of transferring the PDU session corresponding to the SMF + PGW-C to the 4G communication system, or the priority is used for indicating the priority of transferring the SMF + PGW-C to the 4G communication system;

the UDM + HSS sends the first SMF + PGW-C address and an access point name APN to a Mobility Management Entity (MME); wherein the APN corresponds to the DNN.

19. The method of claim 18, wherein the determining the first SMF + PGW-C address used by the UE in the 4G communication system according to the priority comprises:

20. The method of claim 18, further comprising:

21. The method according to any of claims 18 to 20, wherein the correspondence between DNN, SMF + PGW-C and priority comprises:

corresponding relation of DNN, S-NSSAI, SMF + PGW-C and priority; or,

corresponding relation among APN corresponding to DNN, single network slice selection auxiliary information S-NSSAI, SMF + PGW-C and priority; or,

and the PDU session identification, the SMF + PGW-C and the priority.

22. A method of session transfer, the method comprising:

the method comprises the steps that a protocol data unit PDU session of user equipment UE stored by a unified data management + home subscription server UDM + HSS is transferred to a corresponding relation of an access point name APN used in a 4G communication system, a session management function + control plane SMF of a protocol data network gateway + PGW-C and priority; the priority is used for indicating the priority of transferring the PDU session corresponding to the SMF + PGW-C to the 4G communication system, or the priority is used for indicating the priority of transferring the SMF + PGW-C to the 4G communication system;

and the UDM + HSS sends the first SMF + PGW-C address and the APN corresponding to the first SMF + PGW-C address to a Mobility Management Entity (MME).

23. The method of claim 22, wherein the UDM + HSS determining the first SMF + PGW-C address used by the UE in the 4G communication system based on the stored priority comprises:

24. The method of claim 22, further comprising:

25. The method according to any of claims 22 to 24, wherein the correspondence between APN, SMF + PGW-C and priority comprises:

corresponding relation of DNN, S-NSSAI, SMF + PGW-C and priority; or,

and the PDU session identification, the SMF + PGW-C and the priority.

26. A User Equipment (UE), comprising:

a sending module, configured to send a first message to an access and mobility management function AMF, where the first message is used to establish a protocol data unit PDU session; the first message comprises a PDU session establishment request and priority information, wherein the priority information is used for indicating the priority of transferring the PDU session which is requested to be established by the UE to a 4G communication system;

27. The UE of claim 26, wherein the UE further comprises:

an application using the PDU session;

a UE routing strategy URSP stored by the UE;

28. The UE of claim 26 or 27, wherein the second message further comprises: priority information of the PDU session determined by a network.

29. The UE of claim 26 or 27, wherein the UE further comprises: and the processing module is used for determining a first PDU session transferred to the 4G communication system according to the priority information of each PDU session corresponding to the used data network name DNN when the UE moves from the 5G communication system to the 4G communication system.

30. The UE of claim 29, wherein the processing module is specifically configured to:

31. An access and mobility management function, AMF, comprising:

a sending module, configured to send, to a mobility management entity MME, information of a protocol data network PDN connection corresponding to a first protocol data unit PDU session when a user equipment UE moves from a 5G communication system to a 4G communication system, where the information of the PDN connection is used for the MME to establish a PDN connection for the UE;

32. The AMF of claim 31, further comprising: a receiving module to:

receiving priority information of the first PDU session, which is sent by a first session management function, a control plane SMF of a protocol data network gateway and a PGW-C;

33. The AMF of claim 32, wherein the receiving module is specifically configured to:

34. The AMF of claim 33, further comprising: a processing module;

the processing module is specifically configured to:

if the priority of the first PDU session is higher than that of the second PDU session, allocating an evolved packet system bearer identity (EBI) for the first PDU session;

or,

the processing module is specifically configured to:

or,

the processing module is specifically configured to:

or,

the processing module is specifically configured to:

35. The AMF of claim 34, wherein the EBI allocation request includes an identification of the first PDU session, and wherein the processing module is further configured to determine a first DNN corresponding to the first PDU session based on the identification of the first PDU session.

36. The AMF of claim 34, wherein the processing module is further configured to:

selecting the priority of the auxiliary information S-NSSAI by the single network slice corresponding to the stored SMF + PGW-C, and determining the priority corresponding to the first SMF + PGW-C and the priority corresponding to the second SMF + PGW-C;

or,

and acquiring the corresponding priority of each SMF + PGW-C.

37. The AMF according to any of claims 31 to 36, wherein the sending module is further configured to send, to the MME, information of a PDN connection corresponding to a fourth PDU session, the fourth PDU session using the same DNN and SMF + PGW-C as the first PDU session.

38. The AMF of any of claims 31 to 36, further comprising: a processing module;

or,

39. The AMF of claim 33, wherein the receiving module is specifically configured to:

40. The AMF of claim 32, wherein the priority information sent by the UE and received by the receiving module comprises:

the priority of the S-NSSAI corresponding to the PDU session; or,

the priority of S-NSSAI and DNN corresponding to the PDU session; or,

a priority of an application using the PDU session.

41. A session management function + protocol data network gateway control plane SMF + PGW-C, the SMF + PGW-C comprising:

the processing module is used for acquiring priority information of PDU session transfer of User Equipment (UE) to a 4G communication system in the process of establishing the PDU session of the UE;

and the sending module is used for sending the priority information to a unified data management plus home subscription server (UDM plus HSS) or an access and mobility management function (AMF).

42. The SMF + PGW-C of claim 41, wherein the SMF + PGW-C further comprises: a receiving module;

or,

the priority information is the priority of transferring the PDU session to a 4G communication system, which is determined by the processing module according to the single network slice selection auxiliary information S-NSSAI of the PDU session;

or,

43. A unified data management + home subscription server, UDM + HSS, wherein the UDM + HSS comprises:

the storage module is used for storing the corresponding relation between the data network name DNN used by the protocol data unit PDU session of the user equipment UE, the session management function + the address and the priority of the control plane SMF + PGW-C of the protocol data network gateway; the priority is used for indicating the priority of transferring the PDU session corresponding to the SMF + PGW-C to the 4G communication system, or the priority is used for indicating the priority of transferring the SMF + PGW-C to the 4G communication system;

a sending module, configured to send the first SMF + PGW-C address and an access point name APN to a mobility management entity MME; wherein the APN corresponds to the DNN.

44. The UDM + HSS of claim 43, wherein the processing module is specifically configured to:

45. The UDM + HSS of claim 43, wherein the UDM + HSS further comprises: a receiving module;

if yes, the storage module stores the corresponding relation between the address of the SMF + PGW-C and the priority.

46. The UDM + HSS according to any of claims 43 to 45, wherein the correspondence between DNN, SMF + PGW-C and priority comprises:

corresponding relation of DNN, S-NSSAI, SMF + PGW-C and priority; or,

and the PDU session identification, the SMF + PGW-C and the priority.

47. A unified data management + home subscription server, UDM + HSS, wherein the UDM + HSS comprises:

the storage module is used for storing the corresponding relation between the access point name APN used in the protocol data unit PDU session transfer of the user equipment UE to the 4G communication system, the address and the priority of the session management function + the control plane SMF + PGW-C of the protocol data network gateway; the priority is used for indicating the priority of transferring the PDU session corresponding to the SMF + PGW-C to the 4G communication system, or the priority is used for indicating the priority of transferring the SMF + PGW-C to the 4G communication system;

a sending module, configured to send the first SMF + PGW-C address and an APN corresponding to the first SMF + PGW-C address to a mobility management entity MME.

48. The UDM + HSS of claim 47, wherein the processing module is specifically configured to determine, according to the correspondence, an address of an SMF + PGW-C with a highest priority among the stored SMF + PGW-cs as the first SMF + PGW-C address.

49. The UDM + HSS of claim 47, wherein the UDM + HSS further comprises:

50. The UDM + HSS according to any of claims 47 to 49, wherein the correspondence between APN, SMF + PGW-C and priority comprises:

corresponding relation of DNN, S-NSSAI, SMF + PGW-C and priority; or,

and the PDU session identification, the SMF + PGW-C and the priority.