Upf switching method and device, computer device and computer readable medium

Abstract

The present disclosure provides a UPF switching method applied to an SMF, comprising: in the case that a first UPF corresponding to a first PDU session cannot provide services for a UE, selecting a second UPF, obtaining an address of the second UPF, and instructing the second UPF to establish an N3 tunnel; wherein the first PDU session is a current PDU session, the second UPF is a target UPF for switching and corresponds to a second PDU session; sending a reestablishment notification message to the UE, the reestablishment notification message carrying the address of the second UPF and a session reestablishment flag for instructing the UE to reestablish the PDU session; receiving a reestablishment response message sent by the UE, and obtaining a session identifier carried in the reestablishment response message; and providing a session management function for the second PDU session when it is determined according to the session identifier that the UE has completed session reestablishment. Under the premise of guaranteeing service continuity requirements, the present disclosure reduces signaling overhead and delay caused by PDU session anchor point switching, avoids service interruption, is easy to implement, and has low cost. The present disclosure also provides a UPF switching device, a user terminal, a computer device, and a readable medium.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of communication, in particular to a UPF switching method and device, computer equipment and computer readable medium. BACKGROUND

[0002] A mobile communication system is composed of user terminals, base stations and core network devices. In the existing 5G communication system, a PDU (Protocal Data Unit) session represents a data service connection between a terminal and a DN (Data Network). The PDU session is of the IPv4, IPv6 or other types. Generally, the establishment process of a session is initiated by a UE (User Equipment) sending a session establishment request. The request message is transmitted to the SMF (Session Management Function) through the AMF (Authentication Management Function). The SMF selects one or more UPFs as session anchors to transmit data between the UE and the DN. Due to the movement of the UE, when the SMF considers that the current UPF can no longer continue to serve the UE, it can select a suitable new UPF and possibly allocate a new IP (Internet Protocol) address, and then notify the UE to rebuild the session.

[0003] According to the description of the existing technical specification for service continuity, in order to meet the requirements of different terminals in the process of movement for service continuity, the 5G communication system defines three different levels of session and service continuity modes (SSC mode) for PDU sessions. For SSC mode 2 and SSC mode 3, if the PDU session anchor UPF needs to be changed due to the movement of the UE, the SMF will notify the UE and require it to perform a session rebuilding process initiated by the UE.

[0004] In the current session and service continuity strategy, UPF switching necessarily requires a complete notification process and a complete new session establishment process between the UE and the SMF. The construction and exchange of signaling can cause a large service discontinuity. SUMMARY

[0005] The present disclosure provides a UPF switching method, device, computer equipment and computer readable medium.

[0006] In a first aspect, the embodiments of the present disclosure provide a UPF switching method applied to a session management function entity SMF, and the method comprises:

[0007] In a case that a first user plane function entity (UPF) corresponding to a first protocol data unit (PDU) session cannot provide services for a user terminal, a second UPF is selected, an address of the second UPF is obtained, and the second UPF is instructed to establish an N3 tunnel; wherein the first PDU session is a current PDU session, and the second UPF is a target UPF for switching and corresponds to a second PDU session.

[0008] A reestablishment notification message is sent to the user terminal, and the reestablishment notification message carries the address of the second UPF and a session reestablishment flag for instructing the user terminal to reestablish a PDU session.

[0009] A reestablishment response message sent by the user terminal is received, and a session identifier carried in the reestablishment response message is obtained.

[0010] When it is determined according to the session identifier that the user terminal has completed session reestablishment, a session management function is provided for the second PDU session.

[0011] In another aspect, the embodiments of the present disclosure also provide a UPF switching method applied to a user terminal, and the method comprises the following steps.

[0012] A reestablishment notification message sent by a session management function entity (SMF) is received, and the reestablishment notification message is sent by the SMF in a case that a first protocol data unit (PDU) session corresponding to a first user plane function entity (UPF) cannot provide services for a user terminal, and the first PDU session is a current PDU session.

[0013] When a session reestablishment flag is obtained from the reestablishment notification message and an address of a second UPF is obtained from the reestablishment notification message, the second UPF is a target UPF for switching and corresponds to a second PDU session.

[0014] A second PDU session is reestablished locally according to at least attribute information of the first PDU session and the address of the second UPF.

[0015] A session identifier is determined according to a reestablishment result of the second PDU session, and a reestablishment response message carrying the session identifier is sent to the SMF, and the session identifier is an identifier of the first PDU session or an identifier of the second PDU session.

[0016] In another aspect, the embodiments of the present disclosure also provide a UPF switching apparatus, which is a session management function entity (SMF). The UPF switching apparatus comprises a selection module, a sending module, a receiving module and a processing module. The selection module is configured to select a second UPF, obtain an address of the second UPF, and instruct the second UPF to establish an N3 tunnel, in a case that a first UPF corresponding to a first protocol data unit (PDU) session is unable to provide services for a user terminal. The first PDU session is a current PDU session, and the second UPF is a target UPF for switching and corresponds to a second PDU session.

[0017] The sending module is configured to send a reestablishment notification message to the user terminal, wherein the reestablishment notification message carries the address of the second UPF and a session reestablishment flag for instructing the user terminal to reestablish a PDU session.

[0018] The receiving module is configured to receive a reestablishment response message sent by the user terminal and obtain a session identifier carried in the reestablishment response message.

[0019] The processing module is configured to provide session management functions for the second PDU session, when it is determined that the user terminal has completed session reestablishment according to the session identifier.

[0020] In another aspect, the embodiments of the present disclosure also provide a user terminal. The user terminal comprises a receiving module, an obtaining module, a session reestablishment module and a sending module. The receiving module is configured to receive a reestablishment notification message sent by a session management function entity (SMF). The reestablishment notification message is sent by the SMF in a case that a first protocol data unit (PDU) session corresponding to a first user plane function entity (UPF) is unable to provide services for a user terminal. The first PDU session is a current PDU session.

[0021] The obtaining module is configured to obtain a session reestablishment flag from the reestablishment notification message, and obtain an address of a second UPF from the reestablishment notification message. The second UPF is a target UPF for switching and corresponds to a second PDU session.

[0022] The session reestablishment module is configured to reestablish the second PDU session locally according to at least attribute information of the first PDU session and the address of the second UPF.

[0023] The sending module is configured to determine a session identifier according to a reestablishment result of the second PDU session, and send a reestablishment response message carrying the session identifier to the SMF. The session identifier is an identifier of the first PDU session or an identifier of the second PDU session.

[0024] In yet another aspect, the present disclosure also provides a computer device, comprising: one or more processors; a storage device having one or more programs stored thereon; when the one or more programs are executed by the one or more processors, the one or more processors implement the UPF switching method as described above.

[0025] In yet another aspect, the present disclosure also provides a computer readable medium having a computer program stored thereon, wherein the program, when executed, implements the UPF switching method as described above.

[0026] The UPF switching method provided by the present disclosure applies SMF, and the method comprises: in the case that a first UPF corresponding to a first PDU session cannot provide services for a UE, selecting a second UPF, obtaining an address of the second UPF, and instructing the second UPF to establish an N3 tunnel; wherein the first PDU session is a current PDU session, the second UPF is a target UPF for switching and corresponds to a second PDU session; sending a reestablishment notification message to the UE, the reestablishment notification message carrying the address of the second UPF and a session reestablishment flag for instructing the UE to reestablish the PDU session; receiving a reestablishment response message sent by the UE, and obtaining a session identifier carried in the reestablishment response message; and when it is determined according to the session identifier that the UE has completed session reestablishment, providing session management functions for the second PDU session. The present disclosure changes the PDU session reestablishment process, uses standard signaling of the existing PDU session process to realize PDU session anchor point switching, reduces the signaling interaction process between network elements, and can reduce the signaling overhead and delay caused by PDU session anchor point switching and avoid service interruption on the premise of guaranteeing service continuity requirements. Moreover, the present disclosure can be realized by software upgrading of the existing device, is easy to implement, and has low cost. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 UPF switching flowchart provided by the present disclosure with SMF as the execution subject Figure One ;

[0028] Figure 2 UPF switching flowchart provided by the present disclosure with SMF as the execution subject Figure Two ;

[0029] Figure 3 UPF switching flowchart provided by the present disclosure with SMF as the execution subject Figure Three ;

[0030] Figure 4 UPF switching flowchart provided by the present disclosure with UE as the execution subject

[0031] Figure 5A signaling diagram of a UPF switching procedure provided by an embodiment of the present disclosure;

[0032] Figure 6 A structure diagram of a UPF switching apparatus provided by an embodiment of the present disclosure Figure One ;

[0033] Figure 7 A structure diagram of a UPF switching apparatus provided by an embodiment of the present disclosure Figure Two ;

[0034] Figure 8 A structure diagram of a UPF switching apparatus provided by an embodiment of the present disclosure Figure Three ;

[0035] Figure 9 A structure diagram of a user terminal provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0036] In the following, example embodiments will be described more fully with reference to the accompanying drawings, in which example embodiments can, however, be implemented in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided as part of the disclosure to convey the principles of the present disclosure to those skilled in the art, so that the present disclosure can be fully understood.

[0037] As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0038] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and / or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0039] The embodiments described herein can be described with reference to plan views and / or cross-sectional views by virtue of the idealized schematic nature of the drawings. In other words, the example sketches can not depict the specific structural details of the embodiments as the specific structural details can vary depending on the manufacturing techniques and / or tolerances. Therefore, the example sketches are intended to be illustrative, and not a limitation of the embodiments. As such, the embodiments are not limited to the examples illustrated in the drawings, but include modifications that can be made to them based on manufacturing processes.

[0040] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure and will not be interpreted in an overly literal or overly formal sense unless expressly so defined herein.

[0041] In the related art of PDU session anchor point switching, for SSC mode 2, the SMF sends the standard signaling Release Command message and carries the cause value to inform the UE to perform PDU session reconstruction. After the UE receives the Release Command message, the UE immediately releases the original session and starts to attempt to initiate the standard signaling Establishment Request message of the establishment request of the new session. During the time period from the release of the old session to the data transmission through the newly established session again, the UE will not be able to perform data transmission. For SSC mode 3, the SMF sends the standard signaling Modification Command message to inform the UE to perform PDU session reconstruction, the UE starts to attempt to initiate the standard signaling Establishment Request message of the establishment request of the new session, and the data network promises to maintain the old session for a certain period of time to avoid service interruption as much as possible before the establishment of the new session. As can be seen, in the current service continuity strategy, the switching of the UPF necessarily requires the UE and the SMF to inform the UE to switch the UPF and establish a new session through a complete signaling process once, and to establish a new session through a complete signaling process once, which may cause large service discontinuity due to the construction and exchange of the signaling.

[0042] Currently, the related art of enhancing the service continuity of the PDU session anchor point switching process mainly increases the core network load, requires it to maintain new and old resources at the same time, and constructs special hardware that integrates the functions of the access network and the core network elements. Therefore, it is difficult to implement and high in cost.

[0043] To solve the above problems, the embodiments of the present disclosure provide a UPF switching method, as shown in the following Figure 1 The UPF switching method is applied to an SMF and includes the following steps:

[0044] Step 11, in the case that the first UPF corresponding to the first PDU session cannot provide services for the UE, a second UPF is selected, the address of the second UPF is obtained, and the second UPF is instructed to establish an N3 tunnel.

[0045] The first PDU session is a current PDU session, the second UPF is a target UPF for switching, and corresponds to the second PDU session. In this step, the SMF selects the target UPF when it is learned that the original UPF cannot continue to serve the UE, obtains the address of the target UPF, and establishes a connection between the RAN (Radio Access Network) node and the target UPF.

[0046] In step 12, a reestablishment notification message is sent to the UE, and the reestablishment notification message carries the address of the second UPF and a session reestablishment flag for instructing the UE to reestablish the PDU session.

[0047] For SSCmode 2, the reestablishment notification message can be a release command message; for SSCmode 3, the reestablishment notification message can be a modification command message. Both the release command message and the modification command message are standard signaling.

[0048] In this step, the reestablishment notification message sent by the SMF to the UE not only carries the IP address of the target UPF for switching, but also carries a session reestablishment flag for instructing the UE to reestablish the PDU session. In the process of notifying the UE to switch the UPF and establish a new session, the SMF carries the session reestablishment flag in the reestablishment notification message sent to the UE in the notification process, so as to trigger the UE to reestablish the PDU session.

[0049] In step 13, a reestablishment response message sent by the UE is received, and a session identifier carried in the reestablishment response message is obtained.

[0050] In this step, the UE returns a reestablishment response message to the SMF after completing the PDU session reestablishment, and the reestablishment response message carries a session identifier. It should be noted that whether the PDU session reestablishment is successful or not, the session identifier carried in the reestablishment response message is different. For SSCmode 2, the reestablishment response message can be a release complete message; for SSCmode 3, the reestablishment notification message can be a modification complete message. Both the release complete message and the modification complete message are standard signaling.

[0051] In step 14, when it is determined according to the session identifier that the UE has completed the session reestablishment, a session management function is provided for the second PDU session.

[0052] In this step, if the SMF determines according to the session identifier that the UE has completed the session reestablishment, a session management function is provided for the target PDU, so as to complete the PDU session anchor point switching.

[0053] The UPF switching method provided by the embodiments of the present disclosure includes the following steps: in the case that a first UPF corresponding to a first PDU session cannot provide services for a UE, a second UPF is selected, the address of the second UPF is obtained, and the second UPF is instructed to establish an N3 tunnel; wherein the first PDU session is a current PDU session, the second UPF is a target UPF for switching and corresponds to a second PDU session; a reestablishment notification message is sent to the UE, the reestablishment notification message carries the address of the second UPF and a session reestablishment flag for instructing the UE to reestablish the PDU session; a reestablishment response message sent by the UE is received, and the session identifier carried in the reestablishment response message is obtained; when it is determined according to the session identifier that the UE has completed the session reestablishment, a session management function is provided for the second PDU session. The embodiments of the present disclosure change the PDU session reestablishment process, use the standard signaling of the existing PDU session process to realize PDU session anchor point switching, reduce the signaling interaction process between network elements, and can reduce the signaling overhead and delay caused by PDU session anchor point switching and avoid service interruption on the premise of guaranteeing service continuity requirements. Moreover, the embodiments of the present disclosure can be realized by software upgrading of existing devices, are easy to implement, and are low in cost.

[0054] In some embodiments, the SM Cause information element of the reestablishment notification message carries the session reestablishment flag. The session reestablishment flag can be a preset value, and the SMF sets the value of the SM Cause information element of the reestablishment notification message to the preset value to inform the UE that PDU session reestablishment is required.

[0055] In some embodiments, the reestablishment notification message further carries the remaining lifetime (AddressLifeTime IE) of the first UPF and / or the QoS (Quality of Service) information of the second PDU session. The remaining lifetime of the first UPF represents the time during which the first UPF can still provide services for the current PDU session, and after the remaining lifetime arrives, the UE cannot transmit data to the data network through the first PDU session, and therefore, the UE must complete PDU session reestablishment within the remaining lifetime. The QoS information of the second PDU session can be the same as or different from the QoS information of the first PDU session, and the SMF informs the UE of the QoS information of the second PDU session so that the UE reestablishes the second PDU session according to the QoS information.

[0056] In some embodiments, the EPCO (Extended Protocol Configuration Options) information element of the reestablishment notification message carries at least one of the following information: the address of the second UPF, the remaining lifetime of the first UPF, and the QoS information of the second PDU session. That is, one of the above three types of information or any combination thereof is stored in the EPCO information element of the reestablishment notification message.

[0057] In some embodiments, the obtaining the session identity carried in the message (i.e., step 13) comprises: obtaining the session identity carried in the EPCO information element of the reestablishment response message. That is, the session identity is carried in the EPCO information element of the reestablishment response message.

[0058] In some embodiments, the determining that the user terminal has completed session reestablishment according to the session identity (i.e., step 14) comprises the following step: in the case that the session identity is not the identity of the first PDU session, determining that the UE has completed session reestablishment, at this time, the session identity is the identity of the second PDU session.

[0059] In some embodiments, as shown in Figure 2 After the obtaining the session identity carried in the message (i.e., step 13), the UPF switching method can further comprise the following steps:

[0060] Step 14', in the case that the session identity is the identity of the first PDU session, releasing the resources of the second PDU session.

[0061] If the UE reestablishes the PDU session successfully, the identity of the second PDU session is carried in the reestablishment response message; if the UE reestablishes the PDU session unsuccessfully, the identity of the first PDU session is carried in the reestablishment response message, thus, the SMF can determine whether the PDU session is reestablished successfully through the session identity in the reestablishment response message. In the case that the PDU session is reestablished successfully, the SMF provides session management function for the second PDU session, and completes the switching from the anchor point of the first PDU session (i.e., the first UPF) to the anchor point of the second PDU session (i.e., the second UPF) when the remaining lifetime of the first UPF arrives. In the case that the PDU session is not reestablished successfully, the SMF releases the resources of the second PDU session that has been established, and does not perform the switching of the PDU session anchor point any more.

[0062] In some embodiments, as shown in Figure 3 Before the sending the reestablishment notification message to the UE (step 12), the UPF switching method further comprises the following steps:

[0063] Step 12', updating the state of the first PDU session from the connected state to the reestablishment state.

[0064] After the receiving the reestablishment response message sent by the UE (step 13), the UPF switching method further comprises the following steps:

[0065] Step 14''', when it is determined that the UE has completed session reestablishment according to the session identity carried in the reestablishment response message, setting the state of the second PDU session to the connected state.

[0066] In this step, if the SMF obtains the identifier of the second PDU session from the session reestablishment response message, it indicates that the UE has completed the session reestablishment, and the switching from the first UDP to the second UDP has been completed, and the state of the PDU session is updated, and the state of the second PDU session is set to the connected state.

[0067] The embodiments of the present disclosure also provide a UPF switching method, as shown in the following. Figure 4 The UPF switching method is applied to a user terminal and includes the following steps.

[0068] In step 41, a reestablishment notification message sent by the SMF is received. The reestablishment notification message is sent by the SMF in a case where it is determined that the first UPF corresponding to the first PDU session cannot provide services for the user terminal, and the first PDU session is the current PDU session.

[0069] In this step, the UE receives the reestablishment notification message sent by the SMF.

[0070] In step 42, a session reestablishment flag is obtained from the reestablishment notification message, and the address of the second UPF is obtained from the reestablishment notification message. The second UPF is the target UPF for switching and corresponds to the second PDU session.

[0071] In this step, if the UE obtains the session reestablishment flag from the reestablishment notification message, it indicates that the reestablishment notification message is used to trigger the UE to perform PDU session reestablishment, and the UE obtains the address of the second UPF corresponding to the second PDU session from the reestablishment notification message.

[0072] In step 43, the second PDU session is locally reestablished according to at least the attribute information of the first PDU session and the address of the second UPF.

[0073] Since only the UPF anchor point is replaced, the basic attributes of the PDU session such as the session type, service continuity requirement, destination DN (data network name), and S-NSSAI (Single Network Slice Selection Assistance information) do not change for the UE, and therefore the UE can successfully complete the establishment of the new session locally according to the new address carried in the received reestablishment notification message and the basic attributes of the PDU session, and only needs to allocate a PDU session identifier for the new session.

[0074] In step 44, the session identifier is determined according to the reestablishment result of the second PDU session, and a reestablishment response message carrying the session identifier is sent to the SMF. The session identifier is the identifier of the first PDU session or the identifier of the second PDU session.

[0075] In this step, if the PDU session is successfully reconstructed (i.e., the second PDU session is successfully established), the second PDU session identifier is carried in the reconstruction response message; if the PDU session is not successfully reconstructed (i.e., the second PDU session is not successfully established), the first PDU session identifier is carried in the reconstruction response message.

[0076] For SSC mode 2, the reconstruction response message can be a release complete message; for SSC mode 3, the reconstruction notification message can be a modification complete message. Both the release complete message and the modification complete message are standard signaling.

[0077] The UPF switching method provided by the embodiments of the present disclosure is applied to a UE, and the method comprises the following steps: receiving a reconstruction notification message sent by an SMF, the reconstruction notification message being sent by the SMF in a case where it is determined that a first UPF corresponding to a first PDU session cannot provide services for the UE, the first PDU session being a current PDU session; when a session reconstruction flag is acquired from the reconstruction notification message and an address of a second UPF is acquired from the reconstruction notification message, the second UPF being a target UPF for switching and corresponding to a second PDU session; locally reconstructing the second PDU session according to at least attribute information of the first PDU session and the address of the second UPF; determining a session identifier according to a second PDU session reconstruction result, and sending a reconstruction response message carrying the session identifier to the SMF, the session identifier being an identifier of the first PDU session or an identifier of the second PDU session. The embodiments of the present disclosure change the PDU session reconstruction process, implement PDU session anchor point switching by using standard signaling of an existing PDU session process, reduce signaling interaction processes between network elements, and can reduce signaling overhead and delay caused by PDU session anchor point switching and avoid service interruption on the premise of guaranteeing service continuity requirements. Moreover, the embodiments of the present disclosure can be implemented by software upgrading of existing devices, are easy to implement, and are low in cost.

[0078] In some embodiments, the UPF switching method further comprises the following steps: when the session reconstruction flag is acquired from the reconstruction notification message, QoS information of the second PDU session is acquired from the reconstruction notification message.

[0079] The locally reconstructing the second PDU session according to at least the attribute information of the first PDU session and the address of the second UPF (i.e., step 43) comprises the following steps: locally reconstructing the second PDU session according to the attribute information of the first PDU session, the address of the second UPF, and the QoS information of the second PDU session.

[0080] The QoS information of the second PDU session can be the same as or different from the QoS information of the first PDU session, the SMF informs the UE of the QoS information of the second PDU session, and the UE reconstructs the second PDU session according to the QoS information.

[0081] In some embodiments, the UPF switching method further comprises the following steps: obtaining the remaining lifetime of the first UPF from the session reconstruction notification message when the session reconstruction flag is obtained from the session reconstruction notification message.

[0082] The at least reconstructing the second PDU session locally according to the attribute information of the first PDU session and the address of the second UPF (i.e., step 43) comprises: at least reconstructing the second PDU session locally according to the attribute information of the first PDU session and the address of the second UPF within the remaining lifetime of the first UPF. That is, the second PDU session is reconstructed locally according to the attribute information of the first PDU session, the address of the second UPF, and the QoS information of the second PDU session within the remaining lifetime of the first UPF.

[0083] In some embodiments, in the case where the session reconstruction flag is obtained from the session reconstruction notification message, at least one of the following information is obtained from the EPCO information element of the session reconstruction notification message: the address of the second UPF, the remaining lifetime of the first UPF, and the QoS information of the second PDU session. That is, in the case where the session reconstruction notification message is used to trigger PDU session reconstruction, the SMF carries one or any combination of the above three kinds of information in the EPCO information element of the session reconstruction notification message.

[0084] In some embodiments, the obtaining the session reconstruction flag from the session reconstruction notification message (step 42) comprises: obtaining the session reconstruction flag from the SM Cause information element of the session reconstruction notification message. That is, in the case where the session reconstruction notification message is used to trigger PDU session reconstruction, the SMF carries the session reconstruction flag in the SM Cause information element of the session reconstruction notification message.

[0085] In some embodiments, the determining the session identifier according to the second PDU session reconstruction result (i.e., step 44) comprises the following steps: in the case where the second PDU session reconstruction is successful, the session identifier is the identifier of the second PDU session; and in the case where the second PDU session reconstruction fails, the session identifier is the identifier of the first PDU session. In this step, in order to ensure that the data network knows the PDU ID of the reconstructed PDU session, the UE carries the new PDU ID in the reconstruction response message after the new session is established. If the new session reconstruction fails, the old session identifier is carried in the reconstruction response message.

[0086] In some embodiments, the session identifier is carried in the EPCO information element of the reconstruction response message.

[0087] In the embodiments of the present disclosure, the SMF triggers the UE to perform PDU session reestablishment by carrying a session reestablishment flag in the reestablishment notification message, and delivers the IP address of the new UPF and QoS information to the UE through the reestablishment notification message, and processes the reestablishment response message returned by the UE and updates the PDU session ID. The UE can complete the creation of a new PDU session locally according to the reestablishment notification message carrying the session reestablishment flag, the IP address of the new UPF and the QoS information, and informs the new PDU session ID through the reestablishment response message.

[0088] To clearly illustrate the scheme of the embodiments of the present disclosure, the following describes the UPF switching process of the embodiments of the present disclosure in combination with Figure 5 The UPF switching process of the embodiments of the present disclosure is described in detail through a specific example.

[0089] In this example, a PDU session 1 of type IPv4 has been established between the UE and the SMF, and uses SSC mode 3. Due to the movement of the UE, the current UPF1 cannot continue to serve the current PDU session 1, and the target UPF for switching is UPF2. The current 5G network is taken as an example for description, but is not limited thereto, and can also be applied to other network standards with similar functions. As shown in Figure 5 The UPF switching process includes the following steps:

[0090] Step 1: When the SMF learns that the UPF1 can no longer serve the UE, a new UPF selection is performed, i.e., UPF2 is selected, the IP address information of UPF2 is obtained, and UPF2 is instructed to establish a new N3 tunnel.

[0091] Step 2: The SMF marks the state of the PDU session 1 as a reestablishment state, constructs a standard signaling Release Command for the PDU session 1, carries the address of UPF2 and the remaining lifetime of PDU1 and other information in the EPCO information element, sets the value of the 5GSM cause IE information element to 39, and sends the Release Command message to the UE.

[0092] Step 3: The UE receives the Release Command message under the PDU session 1, and if it identifies that the value of the 5GSM cause IE is 39, it obtains the address of UPF2, the remaining lifetime of PDU1 and other information in the EPCO.

[0093] Step 4: The UE creates a PDU session 2 locally according to the address of UPF2, the attribute information and QoS information of the PDU session 1 within the remaining lifetime of PDU1, and allocates a session identifier PDU ID2 for the PDU session 2.

[0094] At this time, data transmission on PDU session 1 can be continued until the remaining lifetime of PDU 1 reaches the end. If the UE successfully creates PDU session 2, step 5 is performed, and data transmission on PDU 2 session can be performed; if the UE fails to create PDU session 2, step 5' is performed.

[0095] Step 5: The UE constructs a Release Complete message under PDU session 1, carries a new PDU ID 2 in the EPCO therein, and sends it to the SMF.

[0096] Step 5': The UE locally releases the resources of PDU session 1 and constructs a Release Complete message, carries the session identifier PDU ID 1 of PDU session 1 in the EPCO therein, and sends it to the SMF.

[0097] Step 6: After the SMF receives the Release Complete message, the session identifier is obtained and saved by checking the EPCO in the Release Complete message. If the session identifier is PDU ID 1, the SMF releases the resources of PDU session 2; if the session identifier is PDU ID 2, the SMF updates PDU session 2 to a connected state and provides session management function for PDU session 2.

[0098] At this time, the UE can transmit data by using PDU session 2, and realize UPF 1 to UPF 2 switching.

[0099] The embodiments of the present disclosure can effectively avoid two-round signaling exchange between the UE and the network side network element, not only can reduce the signaling overhead, but also shorten the service interruption introduced in the PDU session reconstruction process.

[0100] Compared with the related technical solutions, the embodiments of the present disclosure use standard signaling to change the PDU session reconstruction process to shorten the large signaling overhead and delay introduced during session anchor switching, avoid improving the service continuity requirements of the network to the terminal, and can be realized by upgrading the L3 NAS layer protocol software using existing equipment and hardware.

[0101] Based on the same technical concept, the embodiments of the present disclosure also provide a UPF switching device, which can be an SMF, such as Figure 6As shown, the UPF switching apparatus comprises a selection module 101, a sending module 102, a receiving module 103, and a processing module 104. The selection module 101 is configured to, in a case where a first user plane function entity (UPF) corresponding to a first protocol data unit (PDU) session cannot provide services for a user terminal, select a second UPF, obtain an address of the second UPF, and instruct the second UPF to establish an N3 tunnel; wherein the first PDU session is a current PDU session, and the second UPF is a target UPF for switching and corresponds to a second PDU session.

[0102] The sending module 102 is configured to send a reestablishment notification message to the user terminal, wherein the reestablishment notification message carries the address of the second UPF and a session reestablishment flag for instructing the user terminal to reestablish a PDU session.

[0103] The receiving module 103 is configured to receive a reestablishment response message sent by the user terminal and obtain a session identifier carried in the reestablishment response message.

[0104] The processing module 104 is configured to, when it is determined according to the session identifier that the user terminal has completed session reestablishment, provide a session management function for the second PDU session.

[0105] In some embodiments, an SM Cause information element of the reestablishment notification message carries the session reestablishment flag.

[0106] In some embodiments, the reestablishment notification message further carries a remaining lifetime of the first UPF and / or quality of service (QoS) information of the second PDU session.

[0107] In some embodiments, an EPCO information element of the reestablishment notification message carries at least one of the following information: the address of the second UPF, the remaining lifetime of the first UPF, and the QoS information of the second PDU session.

[0108] In some embodiments, the receiving module 103 is configured to obtain the session identifier carried in the EPCO information element of the reestablishment response message.

[0109] In some embodiments, the processing module 104 is configured to, in a case where the session identifier is not an identifier of the first PDU session, determine that the user terminal has completed session reestablishment.

[0110] In some embodiments, as shown in FIG. 1, the UPF switching apparatus further comprises a resource release module 105. Figure 7 The resource release module 105 is configured to, after obtaining the session identifier, in a case where the session identifier is an identifier of the first PDU session, release resources of the second PDU session.

[0111] In some embodiments, as shown in Figure 8 The UPF switching apparatus further includes a state updating module 106, configured to update the state of the first PDU session from a connected state to a reestablishment state before the sending module 102 sends the reestablishment notification message to the user terminal; and set the state of the second PDU session to the connected state after the receiving module 103 receives the reestablishment response message sent by the user terminal, when it is determined according to the session identifier carried in the reestablishment response message that the user terminal has completed session reestablishment.

[0112] Based on the same technical concept, the present disclosure further provides a user terminal, as shown in Figure 9 The user terminal includes a receiving module 201, an obtaining module 202, a session reestablishment module 203 and a sending module 204. The receiving module 201 is configured to receive a reestablishment notification message sent by a session management function entity (SMF), wherein the reestablishment notification message is sent by the SMF when it is determined that a first user plane function entity (UPF) corresponding to a first protocol data unit (PDU) session cannot provide services for the user terminal, and the first PDU session is a current PDU session.

[0113] The obtaining module 202 is configured to obtain a session reestablishment flag from the reestablishment notification message, and obtain an address of a second UPF from the reestablishment notification message, wherein the second UPF is a target UPF for switching and corresponds to a second PDU session.

[0114] The session reestablishment module 203 is configured to reestablish the second PDU session locally according to at least the attribute information of the first PDU session and the address of the second UPF.

[0115] The sending module 204 is configured to determine a session identifier according to the reestablishment result of the second PDU session, and send a reestablishment response message carrying the session identifier to the SMF, wherein the session identifier is an identifier of the first PDU session or an identifier of the second PDU session.

[0116] In some embodiments, the obtaining module 202 is further configured to obtain QoS information of the second PDU session from the reestablishment notification message when the session reestablishment flag is obtained from the reestablishment notification message.

[0117] The session reestablishment module 203 is further configured to reestablish the second PDU session locally according to the attribute information of the first PDU session, the address of the second UPF and the QoS information of the second PDU session.

[0118] In some embodiments, the obtaining module 202 is further configured to, when the session reestablishment flag is obtained from the reestablishment notification message, obtain the remaining lifetime of the first UPF from the reestablishment notification message.

[0119] The session reestablishment module 203 is further configured to, within the remaining lifetime of the first UPF, reestablish the second PDU session locally according to at least the attribute information of the first PDU session and the address of the second UPF.

[0120] In some embodiments, the obtaining module 202 is configured to, when the session reestablishment flag is obtained from the reestablishment notification message, obtain at least one of the following information from the EPCO information element of the reestablishment notification message: the address of the second UPF, the remaining lifetime of the first UPF, and the QoS information of the second PDU session.

[0121] In some embodiments, the obtaining module 202 is configured to obtain the session reestablishment flag from the SM Cause information element of the reestablishment notification message.

[0122] In some embodiments, the sending module 204 is configured to, when the reestablishment of the second PDU session succeeds, carry the session identifier as an identifier of the second PDU session; and when the reestablishment of the second PDU session fails, carry the session identifier as an identifier of the first PDU session.

[0123] In some embodiments, the session identifier is carried in an EPCO information element of the reestablishment response message.

[0124] The embodiments of the present disclosure further provide a computer device, which comprises one or more processors and a storage device; wherein the storage device has stored thereon one or more programs, which, when executed by the one or more processors, cause the one or more processors to implement the UPF switching method provided in the foregoing embodiments.

[0125] The embodiments of the present disclosure further provide a computer readable medium having stored thereon a computer program, wherein the computer program, when executed, implements the UPF switching method provided in the foregoing embodiments.

[0126] Those of ordinary skill in the art will realize and understand, all or certain steps in the methods disclosed above and the functional modules / units in the devices can be implemented as software, firmware, hardware, and appropriate combinations thereof. In hardware implementation, the division between the functional modules / units mentioned in the above description does not necessarily correspond to the division of physical components; for example, one physical component can have multiple functions, or one function or step can be performed by several physical components in cooperation. Certain physical components or all physical components can be implemented as software executed by a processor, such as a central processing unit, a digital signal processor, or a microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, which can include computer storage media (or non-transitory media) and communication media (or transitory media). As is well known to those of ordinary skill in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tapes, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by a computer. Furthermore, it is well known to those of ordinary skill in the art that communication media typically embodies computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and can include any information delivery media.

[0127] Example embodiments have been disclosed herein and, although the use of specific terms is expressly used herein, they are intended in a generic sense only and, unless expressly stated to the contrary, are not intended to limit the application of the present disclosure. In some instances, features, characteristics or aspects described in connection with a particular embodiment can be used, alone or in combination with other embodiments, and in conjunction with the description of other embodiments, unless expressly stated to the contrary. Accordingly, one of ordinary skill in the art will recognize that the various forms and details of the application can be varied, without departing from the scope of the application as outlined in the appended claims.

Claims

1. A UPF switching method, characterized in that, The method, applied to the Session Management Function Entity (SMF), includes: If the first user plane functional entity (UPF) corresponding to the first protocol data unit (PDU) session cannot provide services to the user terminal, a second UPF is selected, the address of the second UPF is obtained, and the second UPF is instructed to establish an N3 tunnel; wherein, the first PDU session is the current PDU session, the second UPF is the target UPF for handover, and corresponds to the second PDU session; A reconstruction notification message is sent to the user terminal, the reconstruction notification message carrying the address of the second UPF and a session reconstruction flag used to instruct the user terminal to rebuild the PDU session; Receive a reconstruction response message sent by the user terminal, and obtain the session identifier carried in the reconstruction response message, wherein the session identifier is the identifier of the first PDU session or the identifier of the second PDU session; If the session identifier is the identifier of the second PDU session, it is determined that the user terminal has completed session reconstruction and provides session management functions for the second PDU session.

2. The method of claim 1, wherein, The reconstruction notification message also carries the remaining lifetime of the first UPF and / or the QoS information of the second PDU session.

3. The method of claim 2, wherein, The EPCO cell of the reconstruction notification message carries at least one of the following information: the address of the second UPF, the remaining lifetime of the first UPF, and the QoS information of the second PDU session.

4. The method of claim 1, wherein, After obtaining the session identifier carried therein, the method further includes: If the session identifier is the identifier of the first PDU session, the resources of the second PDU session are released.

5. The method according to any one of claims 1 to 4, characterized in that, Before sending the reconstruction notification message to the user terminal, the method further includes: Update the state of the first PDU session from the connected state to the rebuilt state; After receiving the reconstruction response message sent by the user terminal, the method further includes: When it is determined that the user terminal has completed session reconstruction based on the session identifier carried in the reconstruction response message, the state of the second PDU session is set to connected state. 6.A UPF switching method, characterized in that, Applied to a user terminal, the method includes: Receive a reconstruction notification message sent by the Session Management Function Entity (SMF). The reconstruction notification message is sent by the SMF when it determines that the first User Plane Function Entity (UPF) corresponding to the first Protocol Data Unit (PDU) session cannot provide services to the user terminal. The first PDU session is the current PDU session. When a session reconstruction flag is obtained from the reconstruction notification message, the address of the second UPF is obtained from the reconstruction notification message. The second UPF is the target UPF for switching and corresponds to the second PDU session. The second PDU session is reconstructed locally, based at least on the attribute information of the first PDU session and the address of the second UPF; The session identifier is determined based on the second PDU session reconstruction result, and a reconstruction response message carrying the session identifier is sent to the SMF. The session identifier is either the identifier of the first PDU session or the identifier of the second PDU session. The step of determining the session identifier based on the second PDU session reconstruction result includes: If the second PDU session is successfully rebuilt, the session identifier is the identifier of the second PDU session; In the event that the reconstruction of the second PDU session fails, the session identifier shall be the identifier of the first PDU session.

7. The method of claim 6, wherein, The method further includes: When a session reconstruction flag is obtained from the reconstruction notification message, the QoS information of the second PDU session is obtained from the reconstruction notification message; The step of reconstructing the second PDU session locally based at least on the attribute information of the first PDU session and the address of the second UPF includes: The second PDU session is reconstructed locally based on the attribute information of the first PDU session, the address of the second UPF, and the QoS information of the second PDU session.

8. The method of claim 6 or 7, wherein, The method further includes: When the session reconstruction flag is obtained from the reconstruction notification message, the remaining lifetime of the first UPF is obtained from the reconstruction notification message; The step of reconstructing the second PDU session locally based at least on the attribute information of the first PDU session and the address of the second UPF includes: During the remaining lifetime of the first UPF, the second PDU session is rebuilt locally at least based on the attribute information of the first PDU session and the address of the second UPF.

9. The method of claim 8, wherein, If a session reconstruction marker is obtained from the reconstruction notification message, at least one of the following information is obtained from the EPCO information element of the reconstruction notification message: the address of the second UPF, the remaining lifetime of the first UPF, and the QoS information of the second PDU session.

10. A UPF switching apparatus, comprising: The UPF switching device is a Session Management Function Entity (SMF), comprising a selection module, a sending module, a receiving module, and a processing module. The selection module is used to select a second UPF, obtain the address of the second UPF, and instruct the second UPF to establish an N3 tunnel when the first User Plane Function Entity (UPF) corresponding to the first Protocol Data Unit (PDU) session cannot provide services to the user terminal. The first PDU session is the current PDU session, and the second UPF is the target UPF for switching and corresponds to the second PDU session. The sending module is used to send a reconstruction notification message to the user terminal. The reconstruction notification message carries the address of the second UPF and a session reconstruction flag used to instruct the user terminal to rebuild the PDU session. The receiving module is used to receive the reconstruction response message sent by the user terminal and obtain the session identifier carried therein, wherein the session identifier is the identifier of the first PDU session or the identifier of the second PDU session; The processing module is used to determine that the user terminal has completed session reconstruction when the session identifier is the identifier of the second PDU session, and to provide session management functions for the second PDU session.

11. A user terminal, characterized in that It includes a receiving module, an acquiring module, a session reconstruction module, and a sending module. The receiving module is used to receive a reconstruction notification message sent by the Session Management Function Entity (SMF). The reconstruction notification message is sent by the SMF when it determines that the first User Plane Function Entity (UPF) corresponding to the first Protocol Data Unit (PDU) session cannot provide services to the user terminal. The first PDU session is the current PDU session. The acquisition module is used to, when a session reconstruction flag is obtained from the reconstruction notification message, obtain the address of the second UPF from the reconstruction notification message, where the second UPF is the target UPF for switching and corresponds to the second PDU session; The session reconstruction module is used to reconstruct the second PDU session locally, based at least on the attribute information of the first PDU session and the address of the second UPF. The sending module is used to determine a session identifier based on the second PDU session reconstruction result, and send a reconstruction response message carrying the session identifier to the SMF. The session identifier is either the identifier of the first PDU session or the identifier of the second PDU session. Wherein, if the second PDU session reconstruction is successful, the session identifier is the identifier of the second PDU session; if the second PDU session reconstruction fails, the session identifier is the identifier of the first PDU session.

12. A computer device, comprising: One or more processors; A storage device on which one or more programs are stored; When the one or more programs are executed by the one or more processors, the one or more processors implement the UPF switching method as described in any one of claims 1-9.

13. A computer-readable medium having a computer program stored thereon, wherein, When the program is executed, it implements the UPF switching method as described in any one of claims 1-9.

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