System, method and device for recovering service bearer, core network side network element and medium

Abstract

The embodiment of the invention provides a system, a method and a device for recovering service bearing, a core network side network element and a medium, and relates to the technical field of mobile communication, and the technical scheme of the embodiment of the invention comprises the following steps: a terminal sends an extension service request to an MME (Mobility Management Entity), and the extension service request is used for requesting to fall back to a 2G or 3G network to carry out specified service. The MME receives the extension service request, if the MME itself is not connected with the 2G network and the 3G network, the MME sends an extension service rejection response to the terminal and sends a detachment request to the terminal, and the detachment request is used for requesting the terminal to perform network attachment again; and deleting packet data network PDN bearer information of the terminal. The success rate of requesting the specified service of the IMS by the UE is improved, and the potential safety hazard of communication interruption is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mobile communication, in particular to a system, method and device for recovering a service bearer, a core network side network element and a medium. BACKGROUND

[0002] In a 4th generation mobile communication technology (4G) or 5G network, a terminal often cannot perform a voice or video service through the network. Taking a 4G scenario as an example, after a user equipment (UE) is attached to the network, the UE needs to send a packet data network (PDN) establishment request for a specified service to a core network side network element of a private network communication system, to request to recover a specified service bearer of an IP multimedia system (IMS) of the UE. At this time, if the internal resources of the core network side network element are abnormal, the PDN bearer information of the UE recorded by the core network side network element is different from the PDN bearer information of the UE carried in the PDN establishment request, and the core network side network element sends a PDN establishment rejection response to the UE, at this time, the specified service bearer of the IMS of the UE is not recovered. For example, in a private network communication system in a mine, due to the narrow and winding tunnels in the mine, which are not conducive to signal transmission, and the passage of large machines and vehicles in the tunnels, which will block the signal, causing more reflected signals and poor signal quality in the tunnels, resulting in more abnormal processing procedures of the non-access stratum (NAS), thereby causing the internal resources of the core network side network element to be abnormal. When the UE detects that the user needs to use the specified service, since the UE did not apply for the specified service bearer of the IMS in the PDN establishment process, the UE needs to send an extended service request to the core network side network element at this time, to request to fall back to a 2G or 3G network to perform the specified service. However, in a specific scenario, the core network side network element is not connected to the 2G and 3G networks, causing the core network side network element to send an extended service rejection response to the UE, so that the UE cannot perform the specified service.

[0003] If the UE needs to perform the specified service of the IMS again later, the UE will re-execute the above failed process, resulting in a low success rate of the UE performing the specified service of the IMS, and a security risk of communication interruption. SUMMARY

[0004] The purpose of the embodiments of the present application is to provide a system, method and device for recovering a service bearer, a core network side network element and a medium, to improve the success rate of the UE requesting the specified service of the IMS. The specific technical solutions are as follows:

[0005] In a first aspect, embodiments of the present application provide a system for recovering a service bearer, the system comprising a terminal and a core network side network element;

[0006] The terminal is configured to send an extended service request to the MME, the extended service request being used to request to fall back to a 2G or 3G network to perform a specified service.

[0007] The core network side network element is configured to receive the extended service request, and if the core network side network element is not connected to the 2G and 3G networks, send an extended service rejection response to the terminal, send a first request to the terminal, the first request being used to request the terminal to re-perform network registration, and delete bearer information of the terminal.

[0008] In some embodiments of the present application, the core network side network element is a mobility management entity (MME), and the system further comprises a serving gateway (serving GW), a SGSN, a packet data network gateway (PDN GW) and a policy and charging rules function (PCRF) to which the terminal is registered.

[0009] The MME is further configured to send a first session deletion request to the serving GW.

[0010] The serving GW is configured to receive the first session deletion request, delete EPS bearer context information of the terminal, and send a first session deletion response to the MME.

[0011] The MME is further configured to send a detach indication to the SGSN.

[0012] The SGSN is configured to receive the detach indication, and send a second session deletion request to the serving GW.

[0013] The serving GW is further configured to receive the second session deletion request, and delete PDP context of the terminal.

[0014] The serving GW is further configured to send a third session deletion request to the PDN GW.

[0015] The PDN GW is configured to release the EPS bearer of the terminal, and send a third session deletion response to the serving GW.

[0016] The PDN GW is further configured to notify the PCRF that the PDN GW has released the EPS bearer of the terminal.

[0017] The serving GW is further configured to send a second session deletion response to the SGSN.

[0018] The SGSN is further configured to send a detach response to the MME.

[0019] In some embodiments of the present application, the core network side network element is an access and mobility management function (AMF), and the system further comprises: a unified data management function (UDM), a session management function (SMF), a user plane function (UPF), a policy control function (PCF) and a base station registered by the terminal.

[0020] The AMF is further configured to send a subscription cancellation request to the UDM.

[0021] The UDM is configured to receive the subscription cancellation request and delete connection information of a PDU session of the terminal.

[0022] The AMF is further configured to send a PDU session release request to the SMF.

[0023] The SMF is configured to receive the PDU session release request, release the PDU session of the terminal, and send an N4 session release request to the UPF.

[0024] The UPF is configured to receive the N4 session release request, release an N4 session of the terminal, and send an N4 session release response to the SMF.

[0025] The SMF is further configured to send a PDU session release response to the AMF.

[0026] The SMF is further configured to send an SM policy association termination request to the PCF.

[0027] The PCF is configured to delete an SM policy of the terminal and send an SM policy association termination response to the SMF.

[0028] The SMF is further configured to send a subscriber data subscription cancellation request to the UDM.

[0029] The UDM is further configured to delete subscriber data of the terminal and send a subscriber data subscription cancellation response to the SMF.

[0030] The SMF is further configured to send a terminal context management deregistration request to the UDM.

[0031] The UDM is further configured to delete context management data of the terminal, send a terminal context management deregistration response to the SMF.

[0032] The AMF is further configured to send an AM policy association termination request to the PCF.

[0033] The PCF is further configured to receive the AM policy association termination request, delete the AM policy association information of the terminal, and send an AM policy association termination response to the AMF.

[0034] The AMF is further configured to send a UE policy association termination request to the PCF.

[0035] The PCF is further configured to receive the UE policy association termination request, delete the UE policy association information of the terminal, and send a UE policy association termination response to the AMF.

[0036] The AMF is further configured to send a connection release request to the base station.

[0037] The base station is configured to receive the connection release request, delete the registration management (RM) context of the terminal, and send a connection release response to the AMF.

[0038] In some embodiments of the present application, the first request is a detach request, and the detach request includes a detach type field, wherein the detach type included in the detach type field is a re-attach required type.

[0039] In some embodiments of the present application, the first request is a deregistration request, and the deregistration request includes a deregistration type field, wherein the deregistration type included in the deregistration type field is a re-registration required type.

[0040] In a second aspect, embodiments of the present application provide a method for restoring a service bearer, applied to a core network side network element, and the method comprises the following steps.

[0041] Receiving an extended service request sent by a terminal, wherein the extended service request is used to request to fall back to a 2G or 3G network to perform a specified service;

[0042] If the core network side network element does not interface with the 2G and 3G networks, sending an extended service rejection response to the terminal;

[0043] Sending a first request to the terminal, wherein the first request is used to request the terminal to re-perform network registration;

[0044] Deleting bearer information of the terminal.

[0045] In some embodiments of the present application, the core network side network element is an MME, and after the step of sending the first request to the terminal, the method further comprises the following steps.

[0046] Sending a first session deletion request to a serving GW, wherein the first session deletion request is used to request the serving GW to delete EPS bearer context information of the terminal;

[0047] receiving a first session deletion response of the serving GW reply;

[0048] sending a detach indication to the SGSN, the detach indication being used to instruct the SGSN to inform a serving GW to delete a PDP context of the terminal and to inform a PDN GW to release an EPS bearer of the terminal.

[0049] In some embodiments of the present application, the core network side network element is an AMF, and after the first request is sent to the terminal, the method further comprises:

[0050] sending an unsubscription request to the UDM, the unsubscription request being used to request to delete connection information of a PDU session of the terminal;

[0051] sending a PDU session release request to the SMF, the PDU session release request being used to request to release a PDU session of the terminal, so that the SMF releases the PDU session of the terminal, and informs a UPF to release an N4 session of the terminal, informs a PCF to delete an SM policy of the terminal, and informs a UDM to delete subscriber data and context management data of the terminal;

[0052] sending an AM policy association termination request to the PCF, the AM policy association termination request being used to request to delete AM policy association information of the terminal;

[0053] sending a UE policy association termination request to the PCF, the UE policy association termination request being used to request to delete UE policy association information of the terminal;

[0054] sending a connection release request to the base station, the connection release request being used to request to delete an RM context of the terminal.

[0055] In some embodiments of the present application, the first request is a detach request, and the detach request comprises a detach type field, wherein the detach type field comprises a detach type that needs to be reattached.

[0056] In some embodiments of the present application, the first request is a deregistration request, and the deregistration request comprises a deregistration type field, wherein the deregistration type field comprises a deregistration type that needs to be re-registered.

[0057] In a third aspect, embodiments of the present application provide a device for restoring a service bearer, applied to a core network side network element, the device comprising:

[0058] a receiving module, configured to receive an extended service request sent by a terminal, the extended service request being used to request to fall back to a 2G or 3G network to perform a specified service;

[0059] send an extended service reject response to the terminal if the core network side network element does not interface with 2G and 3G networks;

[0060] The sending module is further configured to send a first request to the terminal, where the first request is used to request the terminal to re-perform network registration.

[0061] The deleting module is configured to delete bearer information of the terminal.

[0062] In some embodiments of the present application, the core network side network element is an MME,

[0063] The sending module is further configured to, after sending the first request to the terminal, send a first session deletion request to a serving GW, where the first session deletion request is used to request the serving GW to delete EPS bearer context information of the terminal.

[0064] The receiving module is further configured to receive a first session deletion response returned by the serving GW.

[0065] The sending module is further configured to send a detachment indication to an SGSN, where the detachment indication is used to instruct the SGSN to notify a serving GW to delete PDP context of the terminal and notify a PDN GW to release EPS bearer of the terminal.

[0066] In some embodiments of the present application, the core network side network element is an AMF, and the sending module is further configured to:

[0067] after sending the first request to the terminal, send an unsubscription request to the UDM, where the unsubscription request is used to request to delete connection information of a PDU session of the terminal;

[0068] send a PDU session release request to the SMF, where the PDU session release request is used to request to release the PDU session of the terminal, so that the SMF releases the PDU session of the terminal, notifies a UPF to release an N4 session of the terminal, notifies a PCF to delete SM policy of the terminal, and notifies a UDM to delete subscriber data and context management data of the terminal;

[0069] send an AM policy association termination request to the PCF, where the AM policy association termination request is used to request to delete AM policy association information of the terminal;

[0070] send a UE policy association termination request to the PCF, where the UE policy association termination request is used to request to delete UE policy association information of the terminal.

[0071] sending a connection release request to the base station, the connection release request being used to request deletion of an RM context of the terminal.

[0072] In some embodiments of the present application, the first request is a de-attachment request, and the de-attachment request comprises a de-attachment type field, wherein the de-attachment type field comprises a de-attachment type that requires re-attachment.

[0073] In some embodiments of the present application, the first request is a de-registration request, and the de-registration request comprises a de-registration type field, wherein the de-registration type field comprises a de-registration type that requires re-registration.

[0074] In a fourth aspect, embodiments of the present application provide a core network side network element, comprising a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory complete communication with each other through the communication bus.

[0075] The memory is used to store a computer program.

[0076] The processor is used to execute the program stored on the memory, and implement the following steps:

[0077] receiving an extended service request sent by a terminal, the extended service request being used to request falling back to a 2G or 3G network to perform a specified service;

[0078] if the core network side network element is not connected to the 2G and 3G networks, sending an extended service rejection response to the terminal;

[0079] sending a first request to the terminal, the first request being used to request the terminal to re-perform network registration;

[0080] deleting bearer information of the terminal.

[0081] In some embodiments of the present application, the core network side network element is an MME, and the core network side network element is further used to implement the following steps:

[0082] after the first request is sent to the terminal, sending a first session deletion request to a serving GW, the first session deletion request being used to request the serving GW to delete EPS bearer context information of the terminal;

[0083] receiving a first session deletion response replied by the serving GW;

[0084] sending a detach indication to the SGSN, the detach indication being used to instruct the SGSN to inform a serving GW to delete a PDP context of the terminal and to inform a PDN GW to release an EPS bearer of the terminal.

[0085] In some embodiments of the present application, the core network side network element is an AMF, and the core network side network element is further configured to implement the following steps:

[0086] After the first request is sent to the terminal, a cancel subscription request is sent to the UDM, the cancel subscription request being used to request to delete connection information of a PDU session of the terminal;

[0087] A PDU session release request is sent to the SMF, the PDU session release request being used to request to release a PDU session of the terminal, so that the SMF releases the PDU session of the terminal, and informs a UPF to release an N4 session of the terminal, informs a PCF to delete an SM policy of the terminal, and informs a UDM to delete subscriber data and context management data of the terminal;

[0088] An AM policy association termination request is sent to the PCF, the AM policy association termination request being used to request to delete AM policy association information of a PDU session of the terminal;

[0089] A UE policy association termination request is sent to the PCF, the UE policy association termination request being used to request to delete UE policy association information of the terminal;

[0090] A connection release request is sent to the base station, the connection release request being used to request to delete an RM context of the terminal.

[0091] In some embodiments of the present application, the first request is a detach request, and the detach request includes a detach type field, and the detach type field includes a detach type that needs to be reattached.

[0092] In some embodiments of the present application, the first request is a deregistration request, and the deregistration request includes a deregistration type field, and the deregistration type field includes a deregistration type that needs to be re-registered.

[0093] In a fifth aspect, the embodiments of the present application provide a computer readable storage medium, and the computer readable storage medium stores a computer program, and the computer program is executed by a processor to implement the steps of the method for restoring a service bearer according to any one of the preceding aspects.

[0094] In a sixth aspect, the embodiments of the present application further provide a computer program product containing instructions, which, when executed on a computer, cause the computer to perform the method for recovering a service bearer of any one of the above.

[0095] The embodiments of the present application have the following beneficial effects:

[0096] With the above technical solution, when the core network side network element cannot establish the bearer of the specified service of the IMS for the terminal, the core network side network element can delete the bearer information of the terminal synchronously when sending the extended service rejection response to the terminal, and send the first request to the terminal, so that the terminal can re-register the network in time after receiving the first request. During the process of re-registering the network by the terminal, the core network side network element can record the correct bearer information of the terminal again, so that the core network side network element can successfully establish the bearer of the specified service of the IMS based on the correct bearer information of the terminal after the terminal re-sends the PDN establishment request or the PDU establishment request, and the terminal can obtain the bearer of the specified service of the IMS. It can be seen that the embodiments of the present application can recover in time when the bearer of the specified service of the IMS cannot be established, thereby improving the success rate of the UE requesting the specified service of the IMS and reducing the security risk of communication interruption.

[0097] Of course, implementing any product or method of the present application does not necessarily need to achieve all the advantages described above at the same time. BRIEF DESCRIPTION OF DRAWINGS

[0098] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art according to these drawings.

[0099] Figure 1 A flowchart of an attachment process in a 4G scenario provided by the embodiments of the present application;

[0100] Figure 2 A flowchart of a PDN establishment process in a 4G scenario provided by the embodiments of the present application;

[0101] Figure 3 A flowchart of a service request process in a 4G scenario provided by the embodiments of the present application;

[0102] Figure 4 A flowchart of a registration process in a 5G scenario provided by the embodiments of the present application;

[0103] Figure 5 A flowchart of a PDU establishment process in a 5G scenario provided by the embodiments of the present application;

[0104] Figure 6 A flow chart of a service request procedure in a 5G scenario provided by an embodiment of the present application;

[0105] Figure 7 A structural schematic diagram of a system for recovering a service bearer provided by an embodiment of the present application;

[0106] Figure 8 A flow chart of a detach procedure in a 4G scenario provided by an embodiment of the present application;

[0107] Figure 9 A flow chart of a conventional procedure for recovering a service bearer in a 4G scenario;

[0108] Figure 10 A flow chart of a procedure for recovering a service bearer in a 4G scenario provided by an embodiment of the present application;

[0109] Figure 11 A flow chart of a conventional detach procedure in a 5G scenario;

[0110] Figure 12 A flow chart of a detach procedure in a 5G scenario provided by an embodiment of the present application;

[0111] Figure 13 A flow chart of a method for recovering a service bearer provided by an embodiment of the present application;

[0112] Figure 14 A structural schematic diagram of an apparatus for recovering a service bearer provided by an embodiment of the present application;

[0113] Figure 15 A structural schematic diagram of an electronic device provided by an embodiment of the present application. DETAILED DESCRIPTION

[0114] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art based on the present application belong to the scope of protection of the present application.

[0115] First, the registration procedure, the connection establishment procedure and the service request procedure of a user equipment (UE) involved in the embodiments of the present application are described. The UE is also referred to as a terminal.

[0116] Before using a network service, the UE needs to register to the network first, wherein the registration procedure is also referred to as an attach procedure. Referring to Figure 1The registration procedure in the 4G scenario includes the following steps:

[0117] S101, the UE sends an Attach Request to an evolved NodeB (eNodeB).

[0118] The Attach Request can include a Globally Unique Temporary UE Identity (GUTI) or a Permanent Temporary Mobile Subscriber Identity (P-TMSI).

[0119] S102, the eNodeB selects a new Mobility Management Entity (new MME) and forwards the Attach Request to the new MME.

[0120] The eNodeB can select a new MME that is closer to the UE and has lower load based on the network topology and load of each MME.

[0121] It should be noted that the MME currently serving the UE is referred to as the new MME, the MME last serving the UE is referred to as an old Mobility Management Entity (old MME), and the Serving general packet radio service Support Node (SGSN) last serving the UE is referred to as an old SGSN.

[0122] S103a, if the Attach Request includes the GUTI, the new MME obtains the address of the old MME / SGSN through the GUTI and sends an ldentification Request to the old MME / SGSN.

[0123] S103b, the old MME / SGSN verifies the ldentification Request, and if the verification is passed, sends an ldentification Response to the new MME.

[0124] In a case that the International Mobile Subscriber Identity (IMSI) of the UE is recorded in the old MME / SGSN, the ldentification Response includes the IMSI of the UE. Conversely, in a case that the IMSI of the UE is not recorded in the old MME / SGSN, the ldentification Response does not include the IMSI of the UE.

[0125] S104a, if the ldentification Response does not include the IMSI of the UE, the new MME sends an identity request (ldentity Request) to the UE.

[0126] S104b, the UE sends an identity response (ldentity Response) to the new MME. The ldentity Response includes the IMSI of the UE.

[0127] S105a, the new MME performs identity authentication (Authentication) or security (Security) setting for the UE by using a home subscriber server (HSS).

[0128] If the context of the UE does not exist in the new MME, if the Attach Request in S101 is not integrity protected, or the integrity check fails, S105a needs to be performed to perform identity authentication and NAS security setting to activate integrity protection and NAS encryption. Otherwise, S105a can be performed or not performed.

[0129] S105b, the new MME sends an ldentity Request to the UE, receives an ldentity Response sent by the UE, obtains a mobile equipment identity (ME Identity) from the ldentity Response, and sends the ME Identity to an equipment identity register (EIR) to perform a mobile equipment identity check (ME Identity Check) for the UE by the EIR.

[0130] The EIR sends a check result for the UE to the new MME, when the check result indicates success, subsequent procedures are continued, and when the check result is failure, the MME rejects the attachment of the UE and does not continue subsequent procedures.

[0131] S106a, if the Attach Request includes a Ciphered Options Transfer Flag, the new MME sends a Ciphered Options Request to the UE.

[0132] S106b, the UE sends a Ciphered Options Response to the new MME.

[0133] S107a, if the context of the UE exists in the new MME, the new MME sends a Delete Session Request to the serving GW.

[0134] The serving GW sends a Delete Session Request to a Packet Data Network gateway (PDN GW) to cause the PDN GW to delete the EPS bearer of the UE.

[0135] In the case that a Policy and Charging Rules Function (PCRF) is deployed in the system, the PDN GW uses a Policy and Charging Enforcement Function (PCEF) Internet Protocol-Connectivity Access Network (IP-CAN) Session Termination procedure to indicate to the PCRF that the session resources of the UE have been released. And the PDN GW sends a Delete Session Response to the serving GW.

[0136] S107b, the serving GW sends a Delete Session Response to the new MME.

[0137] It should be noted that the functions of S107a and S107b are to clear the EPS bearer of the UE which is recorded in the network but not deleted in the historical attach process when the new MME and the old MME are the same MME.

[0138] S108, if the new MME has not served the UE, the new MME sends an Update Location Request to the HSS.

[0139] S109a, the HSS sends a Cancel Location to the old MME / SGSN.

[0140] S109b, the old MME / SGSN deletes the bearer context of the UE and sends a Cancel Location Ack to the HSS.

[0141] S110a, if there is a bearer context of the UE in the old MME / SGSN, the old MME / SGSN sends a Delete Session Request to the serving GW.

[0142] The serving GW deletes the bearer context of the UE and sends a Delete Session Request to the PDN GW and a Delete Session Response to the serving GW. In the case that a PCRF is deployed in the system, the PDN GW uses a PCEF IP-CAN Session Termination procedure to indicate to the PCRF that the session resource of the UE has been released.

[0143] S110b, the serving GW sends a Delete Session Response to the old MME / SGSN.

[0144] S111, the HSS sends an Update Location Ack to the new MME.

[0145] S112, the new MME sends a Create Session Request to the serving GW.

[0146] S113, the serving GW sends a Create Session Request to the PDN GW.

[0147] S114, if the user policy and charging control (PCC) is deployed in the system, and the Handover Indication flag does not exist in the create session request, the PDN GW performs a PCEF Initiated IP-CAN Session Establishment procedure with the PCRF, and if the Handover Indication flag exists in the create session request, the PDN GW performs a PCEF Initiated IP-CAN Session Modification procedure with the PCRF.

[0148] S115, the PDN GW sends a create session response to the serving GW.

[0149] At this time, the PDN GW can send first downlink data to the serving GW.

[0150] S116, the serving GW sends a create session response to the new MME.

[0151] S117, the new MME sends an attach accept to an eNodeB.

[0152] The attach accept is contained in an initial context setup request.

[0153] S118, the eNodeB sends a radio resource control connection reconfiguration or a radio resource control direct transfer to the UE.

[0154] S119, the UE sends a radio resource control connection reconfiguration complete to the eNodeB.

[0155] S120, the eNodeB sends an initial context setup response to the new MME.

[0156] S121, the UE sends a Direct Transfer to the eNodeB.

[0157] S122, the eNodeB sends an Attach Complete to the new MME.

[0158] At this time, the UE can send First Uplink Data to the PDN GW through the Serving GW.

[0159] S123a, the new MME sends a Modify Bearer Request to the serving GW.

[0160] S123b, if the Modify Bearer Request includes a Handover Indication flag, the Serving GW sends a Modify Bearer Request to the PDN GW.

[0161] S123c, the PDN GW sends a Modify Bearer Response to the serving GW.

[0162] S124, the Serving GW sends a Modify Bearer Response to the new MME.

[0163] At this time, the PDN GW can transmit First Downlink Data to the UE through the Serving GW.

[0164] S125, if the Request Type of the Modify Bearer Response does not indicate handover, and an EPS bearer has been established, and the subscription data indicates that the UE is allowed to hand over to non-3GPP access, and if the PDN GW selected by the new MME is inconsistent with that specified by the HSS, the new MME sends a Notify Request including an Access Point Name (APN) and a PDN GW identity to the HSS.

[0165] S126, the HSS stores the APN and PDN GW identity pair, and sends a Notify Response to the new MME.

[0166] In a 4G scenario, the UE completes network attachment through the process shown in Figure 1 After the network attachment is completed, the UE can send a Modify Bearer Request to the Serving GW through the new MME, as shown in Figure 2The illustrated procedure establishes a PDN connection. Among them, Figure 2 MME in Figure 1 new MME in

[0167] S201, the UE sends a PDN connection request (PDN Connectivity Request) to the MME. Among them, the PDN connection request is also called the PDN establishment request.

[0168] S202, the MME sends a create session request (Create Session Request) to the Serving GW.

[0169] S203, the Serving GW sends a create session request (Create Session Request) to the PDN GW.

[0170] S204, the IP-CAN session establishment or modification (IP-CAN Session Establishment / Modification) procedure is performed between the PDN GW and the PCRF.

[0171] S205, the PDN GW sends a create session response (Create Session Response) to the Serving GW.

[0172] At this time, the PDN GW can send the first downlink data to the Serving GW.

[0173] S206, the Serving GW sends a create session response to the MME.

[0174] S207, the MME sends a bearer setup request (Bearer Setup Request) or downlink NAS transport with PDN connection acceptance (Downlink NAS transport with PDN Connectivity Accept) to the eNodeB.

[0175] S208, the eNodeB sends an RRC connection configuration (RRC Connection Reconfiguration) to the UE.

[0176] S209, the UE sends an RRC connection configuration success (RRC Connection Reconfiguration Complete) to the eNodeB.

[0177] S210, the NodeB sends a Bearer Setup Response to the MME.

[0178] S211, the UE sends a Direct Transfer to the eNodeB.

[0179] S212, the eNodeB sends a PDN Connectivity Complete to the MME.

[0180] At this time, the UE can send First Uplink Data to the PDN GW through the Serving GW.

[0181] S213a, the MME sends a Modify Bearer Request to the Serving GW.

[0182] S213b, the Serving GW sends a Modify Bearer Request to the PDN GW.

[0183] S213c, the PDN GW sends a Modify Bearer Response to the Serving GW.

[0184] S214, the Serving GW sends a Modify Bearer Response to the MME.

[0185] At this time, the PDN GW can transmit First Downlink Data to the UE through the Serving GW.

[0186] S215, the MME sends a Notify Request to the HSS.

[0187] S216, the HSS sends a Notify Response to the MME.

[0188] In the 4G scenario, the UE establishes a PDN connection through the process shown in Figure 2 After detecting that the user needs to perform a specified service of an IP Multimedia Subsystem (IMS), a service request process shown in Figure 3 is performed. For example, the specified service can be a voice service or a video service, etc.

[0189] S301, the UE sends a NAS: Service Request to the eNodeB.

[0190] Wherein, the NAS: Service Request message is contained in the RRC message.

[0191] S302, the eNodeB sends the NAS: Service Request to the MME.

[0192] S303, the MME performs Authentication or Security setting for the UE with the HSS.

[0193] S304, the MME sends the S1 Application Protocol (S1-AP): Initial Context Setup Request to the eNodeB.

[0194] S305, the Radio Bearer Establishment procedure is performed between the eNodeB and the UE.

[0195] S306, the UE sends the Uplink Data to the Serving GW through the eNodeB, and the Serving GW continues to forward the Uplink Data to the PDN GW.

[0196] S307, the eNodeB sends the S1-AP message Initial Context Setup Complete to the MME.

[0197] S308, the MME sends the Modify Bearer Request to the Serving GW.

[0198] At this time, the Serving GW can send the Downlink Data to the UE.

[0199] S309, if the Radio Access Technology Type (RAT Type) included in the Modify Bearer Request is inconsistent with the last used, or the location information of the UE is contained in the Modify Bearer Request, the Serving GW sends the Modify Bearer Request to the PDN GW.

[0200] S310, if the PCC is deployed in the system, the PDN GW performs the PCEF Initiated IP-CAN Session Modification procedure with the PCRF.

[0201] S311, the PDN GW sends a Modify Bearer Response to the Serving GW.

[0202] S312, the Serving GW sends a Modify Bearer Response to the MME.

[0203] However, when the air interface radio link of the UE is abnormal, a Tracking Area Update (TAU) request needs to be sent to the core network side network element, which is used to indicate that the default bearer of the data service of the EPS Bearer Identity (EBI) 5 is restored. After that, the core network side network element sends a TAU success response to the UE, and restores the data service bearer of the UE.

[0204] After 140 milliseconds (ms), the UE sends a PDN establishment request to the core network side network element, which is used to indicate that the default bearer of the IMS voice service of the EBI 6 is restored. At this time, due to the abnormality of the internal resources of the core network side network element, the PDN bearer information of the UE recorded by the core network side network element is abnormal, and the core network side network element sends a PDN establishment rejection response to the UE, and at this time the IMS voice service bearer of the UE is not restored.

[0205] After that, the UE detects that the user needs to use the voice service, and since the IMS voice service bearer of the UE has not been restored, the UE core network side network element sends an Extended service request to request to fall back to the 2G or 3G network for voice service. In the case where the core network side network element is not connected to the 2G and 3G networks, the core network side network element sends an Extended service rejection response to the UE, so that the UE cannot perform the specified service.

[0206] Subsequently, the UE detects that the user needs to use the voice service again, and the process after the above-mentioned sending of the Extended service request is repeatedly performed, resulting in a low success rate of the UE performing the voice service, and a security risk of communication interruption.

[0207] In the 5G scenario, in order to obtain network authorization and use network services, implement mobility tracking and enable reachability, the UE needs to first register to the network through Figure 4 the process shown in the figure.

[0208] S401, the UE sends a Registration Request to a (Radio) Access Network ((R)AN).

[0209] S402, the (R)AN selects a new Access and Mobility Management Function (new AMF).

[0210] It should be noted that the AMF currently serving the UE is referred to as the new AMF, and the AMF last serving the UE is referred to as the old AMF.

[0211] S403, the (R)AN sends a Registration Request to the new AMF.

[0212] S404, the new AMF sends a Network Access and Mobility Management Function (Namf) _Communication_UEContext Transfer Request to the old AMF to request to obtain the UE context information.

[0213] In the case where the Registration Request carries the subscription concealed identifier (SUCI) of the UE, the new AMF can invoke the Namf_Communication_UEContext service of the old AMF.

[0214] The UE context information includes parameters such as a subscription permanent identifier (SUPI), a generic public subscription identifier (GPSI), and a 5G mobility management capability (5GMM Capability).

[0215] S405, the old AMF sends a Namf_Communication_UEContext Transfer response to the new AMF.

[0216] The Namf_Communication_UEContext Transfer response carries the context information of the UE.

[0217] S406, the new AMF sends an Identity Request to the UE.

[0218] In the case that the Registration Request does not carry the SUCI of the UE, the new AMF can send an Identity Request to the UE to request the SUCI of the UE.

[0219] S407. The UE sends an Identity Response to the new AMF. The Identity Response carries the SUCI of the UE.

[0220] S408. The new AMF selects an Authentication Service Function (AUSF). The new AMF can select an AUSF according to the SUPI or SUCI of the UE.

[0221] S409. The new AMF and the AUSF, the new AMF and the UE, and the AUSF and the Unifed Data Management (UDM) perform Authentication or Security setting respectively.

[0222] S410. The new AMF sends a Namf_Communication_Registration Complete Notify to the old AMF.

[0223] S411. The new AMF sends an Identity Request to the UE, and the UE sends an Identity Response to the new AMF. The Identity Request is used to request the Paging Early Indication (PEI) of the UE, and the Identity Response carries the PEI of the UE.

[0224] S412. The new AMF sends an N5g_EIR_Equipment Identity Check_Get to an Equipment Identity Register (EIR) to request the EIR to check the legality of the UE and obtain the check result of the EIR. N5g-eir is a service interface provided by the EIR based on 5G.

[0225] S413. The new AMF selects a UDM.

[0226] The new AMF can select one UDM based on the SUPI of the UE.

[0227] S414a, the new AMF invokes a Network Unified Data Management_User Equipment Context Management_Registration (Nudm_UECM_Registration) service of the UDM.

[0228] S414b, the new AMF invokes a Network Unified Data Management_Subscriber Data Management_Get (Nudm_SDM_Get) service of the UDM.

[0229] Specifically, the new AMF sends an Nudm_SDM_Get message to the UDM for obtaining subscription data from the UDM.

[0230] S414c, the new AMF sends an Nudm_SDM_Subscribe to the UDM.

[0231] Specifically, the new AMF sends an Nudm_SDM_Subscribe to the UDM for subscription data subscription.

[0232] S414d, the UDM sends an Nudm_UECM_Deregistration Notify to the old AMF.

[0233] S414e, the old AMF sends an Nudm_SDM_Unsubscribe to the UDM.

[0234] S415, the new AMF selects a Policy Control Function (PCF).

[0235] S416, the new AMF performs an Access and Mobility (AM) policy association establishment / modification procedure with the PCF.

[0236] S417, the new AMF sends a network session management function (Network Session Management Function, SMF)_Protocol Data Unit Session (PDUSession)_UpdateSMContext / Nsmf_PDU Session_ReleaseSMContext to a session management function (Session Management Function, SMF).

[0237] S418, a non-3GPP interworking function (Non-3GPP InterWorking Function, N3IWF) sends an N2 AMF mobility request (N2 AMF Mobility Request) to the new AMF. Wherein, N2 is an interface standard between different network functions in the 5G network, used to realize the communication between network functions.

[0238] S419, the new AMF sends an N2 AMF mobility response (N2 AMF Mobility Response) to the N3IWF.

[0239] S420a, the new AMF sends Nudm_UECM_Registration to the UDM.

[0240] S420b, the UDM sends Nudm_UECM_Deregistration Notify to the old AMF.

[0241] S420c, the old AMF sends Nudm_SDM_Unsubscribe to the UDM.

[0242] S421a, the new AMF sends a registration acceptance (Registration Accept) to the UE.

[0243] S421b, the new AMF performs UE policy association establishment (UE Policy Association Establishment) with the PCF.

[0244] S422, the UE sends a registration completion (Registration Complete) to the new AMF.

[0245] S423, the new AMF invokes the Nudm_SDM_Info service of the UDM.

[0246] If the access and mobility subscription data acquired by the new AMF in S414b contains an indication that the Steering of Roaming (SOR) information needs to be confirmed, the AMF performs S423 to confirm with the UDM whether the UE has normally received information such as the Carrier Aggregation Group (CAG) and Network Slicing Subscription Change Indication.

[0247] S424, the new AMF invokes the Nudm_UECM_Update service of the UDM.

[0248] In the 5G scenario, the UE completes network registration through the procedure shown in Figure 4 After the procedure shown in Figure 5 The AMF in Figure 5 is the new AMF in Figure 4 .

[0249] S501, the UE sends a PDU session establishment request to the AMF through the (R)AN.

[0250] S502, the AMF selects an SMF.

[0251] S503, the AMF sends a network session management function (Nsmf)_PDU session (PDUSession)_CreateSMContext request to the SMF.

[0252] S504, the SMF performs subscription retrieval / subscription updates with the UDM.

[0253] S505, the SMF sends an Nsmf_PDU Session_CreateSMContext response to the AMF.

[0254] S506, PDU Session authentication / authorization is performed between devices in the system.

[0255] When S506 is performed, authentication can be performed using an external Data Network (DN).

[0256] S507a, the SMF selects a PCF.

[0257] S507b, a Session Management Policy Association Establishment or SMF initiated SM Policy Association Modification procedure is performed between the SMF and the PCF.

[0258] S508, the SMF selects a User Plane Function (UPF).

[0259] S509, the SMF initiates an SM Policy Association Modification procedure with the PCF.

[0260] S510a, the SMF sends an N4 Session Establishment / Modification Request to the UPF. The N4 Session is also referred to as a Packet Forwarding Control Protocol (PFCP) Session, which is used to define the manner in which the UPF identifies, forwards, buffers, marks, reports, and multi-accesses the PDU session.

[0261] S510b, the UPF sends an N4 Session Establishment / Modification Response to the SMF.

[0262] S511, the SMF sends a Namf_Communication_N1N2message transfer to the AMF and receives a response returned by the AMF.

[0263] The Namf_Communication_N1N2message transfer carries an N1 Container and an N2 Container. The N1 Container is a session establishment result sent by the SMF to the UE, and the N2 Container is a resource establishment request sent by the SMF to the (R)AN.

[0264] S512, the AMF sends a N2 PDU Session Request to the (R)AN. Wherein, the N2 PDU Session Request carries the PDU Session Establishment Accept message. N2 refers to the interface between SMF and UPF.

[0265] S513, the user plane connection is established between the (R)AN and the UE according to the access node-specific resource setup message.

[0266] S514, the RAN sends a N2 PDU Session Response to the AMF.

[0267] At this time, the UE can send the initial uplink data (First Uplink Data) to the UPF.

[0268] S515, the AMF sends a Nsmf_PDUSession_UpdateSMContext Request to the SMF.

[0269] S516a, the SMF sends a N4 Session Modifcation Request to the UPF.

[0270] S516b, the UPF sends a N4 Session Modifcation Response to the SMF.

[0271] At this time, the UPF can send the initial downlink data (First Downlink Data) to the UE.

[0272] S516c, the Registration procedure is performed between the SMF and the UDM.

[0273] If the request type of the request involved in S503 is neither "Emergency Request" nor "ExistingEmergency PDU Session", and if the SMF does not register the PDU session, the SMF registers the PDU session with the UDM using Nudm_UECM_Registration.

[0274] S517, the SMF sends a Nsmf_PDUSession_UpdateSMContext Response to the AMF.

[0275] S518, the SMF sends an Nsmf_PDUSession_Session Management Context Status Notify (SMContextStatusNotify) to the AMF.

[0276] S519, the SMF sends an Internet Protocol Version 6 (IPv6) address Configuration to the UPF and the UE.

[0277] If the UE applies for a PDU session of IPv6 type, the SMF issues an IPv6 route advertisement to the UE through the UPF by S519.

[0278] S520, an Unsubscniption procedure is performed between the SMF and the UDM.

[0279] If the PDU session establishment fails after S504, an Unsubscniption procedure is performed between the SMF and the UDM.

[0280] In the 5G scenario, Figure 5 After that, the UE initiates a PDU establishment request to the core network side network element for the second time to establish a bearer for the IMS specified service. Since the second PDU establishment request initiated by the UE is the same as the procedure shown in Figure 5 , the second PDU establishment request procedure is omitted here.

[0281] After that, when the UE needs to request the specified service of the IMS, a service request procedure is initiated, and the service request procedure is as shown in Figure 6 . For example, the specified service can be a voice service or a video service, etc.

[0282] S601, the UE sends a Service Request to the (R)AN.

[0283] S602, the (R)AN sends an N2 message to the AMF. The N2 message is obtained based on the Service Request.

[0284] S603, the AMF performs authentication and security setting for the UE with an Authentication Server Function (AUSF).

[0285] S604, the AMF sends an Nsmf_PDUSession_UpdateSMContext Request to the SMF.

[0286] S605a, the SMF initiates a SMF initiated SM Policy Association Modification procedure with the PCF.

[0287] S605b, the SMF selects a first UPF. The first UPF is a new I-UPF.

[0288] S606a, the SMF sends a N4 Session Modifcation Request to a second UPF. The second UPF is a PSA UPF.

[0289] S606b, the second UPF sends a N4 Session Modifcation Response to the SMF.

[0290] S606c, the SMF sends a N4 Session Establishment Request to the first UPF.

[0291] S606d, the first UPF sends a N4 Session Establishment Response to the SMF.

[0292] S607a, the SMF sends a N4 Session Modifcation Request to the second UPF.

[0293] S607b, the second UPF sends a N4 Session Modifcation Response to the SMF.

[0294] At this time, the second UPF can send Downlink Data to the first UPF.

[0295] S608a, the SMF sends a N4 Session Modifcation Request to a third UPF. The third UPF is an old I-UPF.

[0296] S608b. The third UPF sends N4 Session Modifcation Response to the SMF.

[0297] S609. The third UPF performs Buffered DL data forwarding to the first UPF.

[0298] S610. The third UPF performs Buffered DL data forwarding to the second UPF.

[0299] S611. The SMF sends Nsmf_PDUSession_UpdateSMContext Respopse to the AMF.

[0300] S612. The AMF sends N2 Request to the (R)AN.

[0301] S613. The (R)AN performs Radio Resource Control Connection Reconfiguration procedure with the UE.

[0302] At this time, since a new intermediate UPF is inserted or the intermediate UPF is relocated (case: new I-UPF is inserted or I-UPF is relocated), the UE can send Uplink data to the second UPF through the (R)AN and the first UPF.

[0303] Since the first UPF is removed (case: I-UPF is removed), the UE can send Uplink data to the second UPF through the (R)AN.

[0304] S614. The (R)AN sends N2 Request acknowledgement (ack) to the AMF.

[0305] S615. The AMF sends Nsmf_PDUSession_UpdateSMContext Request to the SMF.

[0306] S616. The SMF initiates Session Management Policy Modification procedure between the PCFs.

[0307] S617a. The SMF sends N4 Session Modifcation Request to the first UPF.

[0308] S617b. The first UPF sends N4 Session Modifcation Response to the SMF.

[0309] At this time the first UPF can send Downlink Data to the UE through the (R)AN.

[0310] S618a. The SMF sends N4 Session Modifcation Request to the second UPF.

[0311] S618b. The second UPF sends N4 Session Modifcation Response to the SMF.

[0312] At this time the second UPF can send Downlink Data to the UE through the (R)AN.

[0313] S619. The SMF sends Nsmf_PDUSession_UpdateSMContext Response to the AMF.

[0314] S620a. The SMF sends N4 Session Modifcation Request to the first UPF.

[0315] S620b. The first UPF sends N4 Session Modifcation Response to the SMF.

[0316] S621a. The SMF sends N4 Session Modifcation Request to the second UPF.

[0317] S621b. The second UPF sends N4 Session Modifcation Response to the SMF.

[0318] S622a. The SMF sends N4 Session Modifcation Request or N4 Session release Request to the third UPF.

[0319] S622b. The third UPF sends N4 Session Modifcation Response or N4 Session release Response to the SMF.

[0320] However, when the air interface of the UE is abnormal, a TAU request needs to be sent to the core network element, which is used to indicate that the default bearer of the data service with an ID (PSI) of 5 of the PDU session is to be resumed. Then the core network element sends a TAU success response to the UE, and the data service bearer of the UE is resumed.

[0321] After 140 ms, the UE sends a PDU establishment request to the core network element, which is used to indicate that the default bearer of the IMS voice service with a PSI of 6 is to be resumed. At this time, due to the abnormality of the internal resources of the core network element, the PDU bearer information of the UE recorded by the core network element is abnormal, the core network element sends a PDU establishment rejection response to the UE, and at this time the IMS voice service bearer of the UE is not resumed.

[0322] After that, when the UE detects that the user needs to use the voice service, since the IMS voice service bearer of the UE is not resumed, the UE sends an extended service request to the core network element to request to fall back to the 2G or 3G network to perform the voice service. In the case where the core network element is not connected to the 2G and 3G networks, the core network element sends an extended service rejection response to the UE, so that the UE cannot perform the specified service.

[0323] Subsequently, when the UE detects that the user needs to use the voice service again, the process after the extended service request is repeatedly performed, resulting in a low success rate of the UE performing the voice service, and a security risk of communication interruption.

[0324] It can be seen that in the 4G and 5G scenarios, the UE has a security risk of communication termination.

[0325] To solve this problem, an embodiment of the present application provides a system for resuming a service bearer, as shown in Figure 7 The system includes a terminal 701 and a core network element 702.

[0326] The terminal 701 is configured to send an extended service request to the core network element 702. The extended service request is used to request to fall back to the 2G or 3G network to perform a specified service. The request carries a service type (Service Type) field, and the field value of the field is circuit domain fallback (Circuit Switched Fallback, CS fallback) or 1XCS fallback, wherein 1XCS fallback indicates falling back to the circuit domain. The specified service is an IMS service, such as a voice service or a video service.

[0327] The core network side network element 702 is configured to receive the extended service request, send an extended service rejection response to the terminal 701 if the core network side network element 702 does not connect to the 2G and 3G networks, send a first request to the terminal 701, where the first request is used to request the terminal 701 to re-perform network registration, and delete the bearer information of the terminal 701.

[0328] The system for restoring a service bearer provided in the embodiments of the present application can, when the core network side network element cannot establish a bearer for a specified service of the terminal after the terminal falls back to the 2G / 3G network, delete the bearer information of the terminal synchronously when sending an extended service rejection response to the terminal, and send a first request to the terminal, so that the terminal can re-perform network registration in a timely manner after receiving the first request. During the process of re-performing network registration by the terminal, the core network side network element can re-record the correct bearer information of the terminal, so that the core network side network element can successfully establish a bearer for the specified service of the IMS based on the correct bearer information of the terminal after the terminal re-sends a PDN establishment request or a PDU establishment request, and the terminal can obtain the bearer for the specified service of the IMS. It can be seen that the embodiments of the present application can restore in a timely manner when the bearer for the specified service of the IMS cannot be established, thereby improving the success rate of the UE requesting the specified service of the IMS and reducing the security risks of communication interruption.

[0329] Moreover, at present, when the voice service cannot be used, the UE can only be manually powered off and on, or manually turned on and off in the "airplane mode", so as to re-perform the attach procedure shown in Figure 1 and the PDN establishment procedure shown in Figure 2 or re-perform the registration procedure shown in Figure 4 and the PDU establishment procedure shown in Figure 5 in the 4G scenario, so as to restore the voice service bearer of the UE. However, this restoration manner is not timely and has low efficiency.

[0330] In the embodiments of the present application, the UE can automatically re-perform the registration and PDN / PDU establishment procedures when the bearer for the specified service cannot be restored, which is equivalent to re-accessing the network, and no manual intervention is required during this period, thereby improving the call success rate of the IMS service and improving the use experience of the user. Moreover, the re-accessing process consumes a short time, which is basically in seconds, so that the restoration efficiency of the specified service is improved, the user use perception is optimized, and the timeliness is improved.

[0331] In the 4G scenario, the first request is a detach request, and the core network side network element is an MME.

[0332] The detach request includes a detach type field, and the detach type field includes a detach type of re-attach required. After the terminal receives the detach request, the terminal re-executes Figure 1 The attach procedure shown in the figure, and Figure 2 The PDN establishment procedure shown in the figure, so that the MME can re-synchronize resources with the terminal once, so that the terminal's PDN bearer information recorded by both parties is consistent, so that the MME can successfully establish a PDN connection with the terminal when it receives a PDN establishment request subsequently, thereby providing the terminal with a specified service bearer without falling back to 2G / 3G for the specified service.

[0333] It should be noted that the data transmission process between the terminal and the MME can pass through the eNodeB, that is, the terminal sends an extended service request to the eNodeB, and the eNodeB forwards the extended service request to the MME; and the MME sends an extended service rejection response to the eNodeB, and the eNodeB forwards the extended service rejection response to the terminal; and the MME sends a detach request to the eNodeB, and the eNodeB forwards the detach request to the terminal.

[0334] In the 5G scenario, the first request is a deregistration request, and the core network side network element is an AMF.

[0335] The deregistration request includes a deregistration type field, and the deregistration type field includes a deregistration type of re-registration required. After the terminal receives the deregistration request, the terminal re-executes Figure 4 The registration procedure shown in the figure, and Figure 5 The PDU establishment procedure shown in the figure, so that the MME can re-synchronize resources with the terminal once, so that the terminal's bearer information recorded by both parties is consistent, so that the MME can successfully establish a PDU connection with the terminal when it receives a PDU establishment request subsequently, thereby providing the terminal with a specified service bearer without falling back to 2G / 3G for the specified service.

[0336] It should be noted that the data transmission process between the terminal and the AMF can pass through the (R)AN, that is, the terminal sends an extended service request to the (R)AN, and the (R)AN forwards the extended service request to the AMF; and the AMF sends an extended service rejection response to the (R)AN, and the (R)AN forwards the extended service rejection response to the terminal; and the AMF sends a deregistration request to the (R)AN, and the (R)AN forwards the deregistration request to the terminal.

[0337] It can be seen that the system for restoring a service bearer provided in the embodiments of the present application is applicable to both 4G and 5G scenarios, that is, when a bearer of a specified service of IMS cannot be established, the system can restore the bearer in time in the 4G / 5G scenario, thereby improving the success rate of a terminal requesting a specified service of IMS, improving user experience, and reducing the security risks of communication interruption.

[0338] In the embodiments of the present application, in the 4G scenario, the core network side network element is an MME, and Figure 7 The system shown in the figure further includes a serving GW, an SGSN, a PDN GW and a PCRF registered by the terminal.

[0339] The MME is further configured to send a first session deletion request to the serving GW.

[0340] The serving GW is configured to receive the first session deletion request, delete the EPS bearer context information of the terminal, and send a first session deletion response to the MME.

[0341] The MME is further configured to send a detach indication to the SGSN.

[0342] The SGSN is configured to receive the detach indication, send a second session deletion request to the serving GW.

[0343] The serving GW is further configured to receive the second session deletion request, and delete the PDP context of the terminal.

[0344] The serving GW is further configured to send a third session deletion request to the PDN GW.

[0345] The PDN GW is configured to release the EPS bearer of the terminal, and send a third session deletion response to the serving GW.

[0346] The PDN GW is further configured to notify the PCRF that the PDN GW has released the EPS bearer of the terminal.

[0347] The serving GW is further configured to send a second session deletion response to the SGSN.

[0348] The SGSN is further configured to send a detach response to the MME.

[0349] In the 4G scenario, a conventional detach process is as shown in the figure. Figure 8

[0350] S801, the MME sends a detach request (Detach Request) to the UE.

[0351] ​Before sending a Detach Request to the UE, the MME can also delete the UE's bearer context stored in the MME.

[0352] S802. The MME sends a Delete Session Request to the serving GW.

[0353] S803: The serving GW releases the EPS bearer context of the UE and returns a DeleteSession Response to the MME.

[0354] S804: If ISR is activated, the MME sends a detach notification (DetachNotification) to the SGSN where the UE is registered.

[0355] S805. The SGSN sends a Delete Session Request to the serving GW, so that the serving GW deletes the PDP context of the UE.

[0356] S806: If the ISR is activated, the serving GW deactivates the ISR. After the ISR is deactivated, the serving GW sends a Delete Session Request to the PDN GW. If the ISR is not activated, S802 triggers the serving GW to send a Delete Session Request to the PDN GW.

[0357] S807. The PDN GW replies a Delete Session Response to the serving GW.

[0358] S808: The PCEF Initiated IP-CAN Session termination process is performed between the PDN GW and the PCRF.

[0359] If the network deploys PCRF, the PCEF-Initiated IP-CAN Session Termination procedure is performed between the PDN GW and the PCRF. During this procedure, the PDN GW notifies the PCRF that the EPS bearer of the UE has been released.

[0360] S809. The serving GW sends a Delete Session Response to the SGSN.

[0361] S810. The SGSN replies a Detach Response to the MME.

[0362] S811, after receiving the Detach Request sent by the MME in S801, the UE sends a Detach Accept to the MME.

[0363] S812, the MME sends a Signalling Connection Release to the eNodeB to release the S1-MME signaling connection of the S1 interface between the eNodeB and the UE.

[0364] Compared with the Detach procedure of Figure 8 , in the embodiment of the present application, the MME or the serving GW does not need to determine whether it is necessary to notify the subsequent core network element to delete the PDN bearer information according to the PDN bearer activation situation of the interrupted voice service and data service, but can directly notify the subsequent core network element to delete the PDN bearer information. In this way, the core network elements can delete the PDN bearer information of the terminal in the core network at one time, which simplifies the internal judgment and processing logic of the Detach procedure and can improve the processing efficiency of the core network elements.

[0365] In combination with Figure 9 and Figure 10 , the following takes the voice service as an example to compare and illustrate the process of resuming the service bearer provided by the embodiment of the present application with the process of resuming the service bearer in the conventional 4G scenario:

[0366] Figure 9 The process of resuming the service bearer in the conventional 4G scenario includes the following steps:

[0367] S901, the terminal sends an Extended Service Request to the MME. The Extended Service Request is triggered when the air interface wireless link of the terminal is abnormal and the specified service needs to be quickly resumed, and the field value of the Service Type field in the Extended Service Request is Circuit Switched Fallback, CS fallback or 1XCS fallback.

[0368] S902, the MME confirms that the terminal requests to fall back to the 2G or 3G network for voice service according to the Service Type field in the Extended Service Request.

[0369] S903, the MME sends an Extended Service Reject response to the terminal when it is found that it is not connected to the 2G and 3G networks.

[0370] S904, the terminal returns to S901 when detecting that voice service needs to be performed. That is, in the state that the terminal does not obtain the voice service bearer of the IMS, the error process shown in S901-S903 is repeatedly performed each time the terminal detects that the user needs to use voice service, resulting in that the terminal cannot provide voice service for the user.

[0371] Figure 10 The process for restoring service bearer in the 4G scenario provided by the embodiment of the present application includes the following steps:

[0372] S1001, the terminal sends an extended service request to the MME.

[0373] S1002, the MME confirms that the terminal requests to fall back to the 2G or 3G network for voice service according to the Service Type field in the extended service request.

[0374] S1003, the MME sends an extended service rejection response to the terminal when checking that the MME does not connect to the 2G and 3G networks.

[0375] S1004, the MME sends a detach request to the terminal. The detach type included in the detach type field carried by the detach request is re-attach required.

[0376] S1005, the MME deletes the PDN bearer information of the terminal.

[0377] S1004 and S1005 can be executed in parallel or sequentially, and the embodiment of the present application does not make specific limitations on this.

[0378] S1006, after receiving the detach request, the terminal confirms that network attachment needs to be performed again according to the re-attach required carried by the detach request, and performs the network attachment process and the PDN establishment process. That is, the terminal can re-execute the process shown in S1011-S1013, and when executing the process shown in S1014-S1016, since the core network side network element re-records the correct PDN bearer information of the UE in the re-attachment process, the terminal can be provided with the IMS voice service bearer. Figure 1 Figure 2 Figure 2

[0379] S1007, the terminal performs a service request process when detecting that voice service needs to be performed. Since the terminal obtains the IMS voice service bearer in the PDN establishment process after re-executing network attachment, the terminal can perform the process shown in S1017 when detecting that the user needs to use voice service, thereby successfully performing voice service. Figure 3

[0380] By comparison​​​​Figure 9 and Figure 10 It can be seen that the embodiment of the application optimizes the automatic connection capability of voice services in abnormal scenarios, enhances the robustness of the core network side against abnormal processes, and improves the performance indicators of the private network.

[0381] In the embodiment of the application, in the 5G scenario, the core network side network element is an AMF, and Figure 7 The system shown in the figure also includes a terminal-registered UDM, SMF, UPF, PCF and base station. The base station belongs to (R)AN.

[0382] The AMF is also configured to send a subscription cancellation request to the UDM. The subscription cancellation request is an Nudm_SDM_Unsubscribe Request, and the subscription cancellation request is used to indicate that the AMF cancels the subscription of the change notification of the PDU session management subscription data between the terminal.

[0383] The UDM is configured to receive the subscription cancellation request and delete the connection information of the PDU session of the terminal. The connection information of the PDU session includes a session identifier, a Quality of Service (QoS) parameter, traffic information, a session state, a Tunnel Endpoint Identifier (TEID) and a security context, etc.

[0384] The AMF is also configured to send a PDU session release request to the SMF. The PDU session release request is an Nsmf_PDUSession_ReleaseSMContext Request.

[0385] The SMF is configured to receive the PDU session release request, release the PDU session of the terminal, and send an N4 session release request (N4 Session Release Request) to the UPF. The N4 Session is also called a PFCP Session, which is used to define the way the UPF identifies, forwards, caches, marks, reports and multi-accesses the PDU session.

[0386] The UPF is configured to receive the N4 session release request, release the N4 session of the terminal, and send an N4 session release response (N4 Session Release Response) to the SMF.

[0387] The SMF is also configured to send a PDU session release response to the AMF. The PDU session release response is an Nsmf_PDUSession_ReleaseSMContext Response.

[0388] The SMF is further configured to send a Session Management (SM) policy association termination request to the PCF.

[0389] The PCF is configured to delete the SM policy of the terminal and send an SM policy association termination response to the SMF.

[0390] The SMF is further configured to send a service data unsubscribe request to the UDM, wherein the service data unsubscribe request is an Nudm_SDM_Unsubscribe Request.

[0391] The UDM is further configured to delete the subscriber data of the terminal and send a subscriber data unsubscribe response to the SMF, wherein the subscriber data unsubscribe response is an Nudm_SDM_Unsubscribe Response.

[0392] The SMF is further configured to send a terminal context management deregistration request to the UDM, wherein the terminal context management deregistration request is an Nudm_UECM_Deregistration Request.

[0393] The UDM is further configured to delete the context management data of the terminal and send a terminal context management deregistration response to the SMF, wherein the terminal context management deregistration response is an Nudm_UECM_Deregistration Response.

[0394] The AMF is further configured to send an AM policy association termination request to the PCF.

[0395] The PCF is further configured to receive an AM policy association termination request, delete AM policy association information of the terminal, and send an AM policy association termination response (AM Policy Association Termination Response) to the AMF, where AM stands for Access and Mobility Management. For example, the AM policy association information includes service area restriction (SAR), radio access technology (RAT) / frequency selection priority (RFSP) index, UE aggregated maximum bit rate (UE-AMBR), and UE slice maximum bit rate (UE-Slice-MBR).

[0396] The AMF is further configured to send a UE policy association termination request (UE Policy Association Termination Request) to the PCF.

[0397] The PCF is further configured to receive the UE policy association termination request, delete UE policy association information of the terminal, and send a UE policy association termination response (UE Policy Association Termination Response) to the AMF. For example, the UE policy association information includes UE route selection policy (URSP) and a policy container of the terminal.

[0398] The AMF is further configured to send a connection release request to the base station.

[0399] The base station is configured to receive the connection release request, i.e., a signalling connection release request (Signalling Connection Release Request), delete a registration management (RM) context of the terminal, and send a connection release response, i.e., a signalling connection release response (Signalling Connection Release Response), to the AMF.

[0400] In a 5G scenario, a conventional deregistration process is as shown in Figure 11

[0401] ​S1101, the UDM sends an Nudm_UECM_Deregistration Notification to the AMF.

[0402] S1102, the AMF sends a De-registration Request to the UE when the deregistration cause included in the Nudm_UECM_Deregistration Notification is Subscription Withdrawn and the UE is in a Connection Management (CM)-Connected state.

[0403] S1103a, the AMF replies to the UDM with an Nudm_UECM_DeRegistration Notification ack.

[0404] S1103b, the AMF sends an Nudm_SDM_Unsubscribe Request to the UDM.

[0405] S1104a, it is judged whether any established PDU session information of the UE is indicated in the Deregistration Notification, if yes, the AMF sends an Nsmf_PDUSession_ReleaseSMContext Request to the SMF.

[0406] S1104b, the SMF sends an N4 Session Release Request to the UPF.

[0407] S1104c, the UPF sends an N4 Session Release Response to the SMF.

[0408] S1104d, the SMF sends an Nsmf_PDUSession_ReleaseSMContext Response to the AMF.

[0409] S1104e, an SM Policy Association Termination procedure is performed between the PCF and the SMF.

[0410] In this process, the SMF sends an SM policy association termination request to the PCF, the PCF deletes the SM policy of the terminal, and sends an SM policy association termination response to the SMF.

[0411] S1104f, the SMF initiates an Nudm_SDM_Unsubscribe procedure to the UDM.

[0412] In this process, the SMF sends a subscriber data unsubscription request to the UDM, i.e. Nudm_SDM_UnsubscribeRequest, the UDM deletes the subscriber data of the terminal, and sends a subscriber data unsubscription response to the SMF, i.e. Nudm_SDM_Unsubscribe Response.

[0413] S1104g, the SMF initiates an Nudm_UECM_Deregistration procedure to the UDM.

[0414] In this process, the SMF sends a terminal context management deregistration request to the UDM, i.e. Nudm_UECM_Deregistration Request, the UDM deletes the context management data of the terminal, and sends a terminal context management deregistration response to the SMF, i.e. Nudm_UECM_Deregistration Response.

[0415] S1105a, the AMF initiates an AM Policy Association Termination procedure to the PCF.

[0416] In this process, the AMF sends an AM policy association termination request to the PCF, i.e. AM Policy Association Termination Request, the PCF receives the AM policy association termination request, deletes the AM policy association information of the terminal, and sends an AM policy association termination response to the AMF, i.e. AM Policy Association Termination Response.

[0417] S1105b, the AMF initiates a UE Policy Association Termination procedure to the PCF.

[0418] In this procedure, the AMF sends a UE Policy Association Termination Request to the PCF, the PCF receives the UE Policy Association Termination Request, deletes the UE policy association information of the terminal, and sends a UE Policy Association Termination Response to the AMF.

[0419] S1106, the UE sends a De-registration Accept to the AMF.

[0420] S1107, the AMF initiates a Signalling Connection Release procedure to the (R)AN to make the (R)AN release the connection with the UE.

[0421] In this procedure, the AMF sends a Signalling Connection Release Request to the base station, the base station receives the Signalling Connection Release Request, deletes the RM context of the terminal, and sends a Signalling Connection Release Response to the AMF.

[0422] In the 5G scenario, the de-registration procedure of the embodiments of the present application is as shown in Figure 12

[0423] S1201, the AMF sends a De-registration Request to the UE.

[0424] Before the AMF sends a De-registration Request to the UE, the AMF can also delete the bearer context of the UE stored by itself.

[0425] S1202, the AMF sends a Nudm_SDM_Unsubscribe Request to the UDM.

[0426] S1203a, it is judged whether any established PDU session information of the UE is indicated in the Deregistration Notification, if so, the AMF sends a Nsmf_PDUSession_ReleaseSMContext Request to the SMF.

[0427] S1203b, the SMF sends a N4 Session Release Request to the UPF.

[0428] ​S1203c. The UPF sends a N4 Session Release Response to the SMF.

[0429] S1203d. The SMF sends a Nsmf_PDUSession_ReleaseSMContext Response to the AMF.

[0430] S1203e. The SM Policy Association Termination procedure is performed between the PCF and the SMF.

[0431] S1203f. The SMF initiates a Nudm_SDM_Unsubscribe procedure with the UDM.

[0432] S1203g. The SMF initiates a Nudm_UECM_Deregistration procedure with the UDM.

[0433] S1204a. The AMF initiates an AM Policy Association Termination procedure with the PCF.

[0434] S1204b. The AMF initiates a UE Policy Association Termination procedure with the PCF.

[0435] S1205. The UE sends a De-registration Accept to the AMF.

[0436] S1206. The AMF initiates a Signalling Connection Release procedure with the (R)AN to make the (R)AN release the connection with the UE.

[0437] By comparing Figure 11 and Figure 12 it can be seen that in the conventional de-registration procedure, the AMF in S1104 needs to determine whether to notify the SMF, UDM and PCF to delete the related bearers according to the activation status of the PDU bearers of the data service and voice service of the terminal. In the embodiment of the present application, the AMF does not need to determine, but can directly notify the SMF, UDM and PCF to delete the bearer information related to the terminal, i.e. the core network side related network elements can clear all related information of the terminal in the core network at one time. Therefore, the embodiment of the present application simplifies the internal processing logic of the de-attachment procedure in the presence of communication anomalies on the one hand, and improves the processing efficiency of the 5G core network for terminal de-attachment on the other hand.

[0438] Based on the same inventive concept, the embodiment of the present application further provides a method for recovering a service bearer, applied to a core network side network element, as shown in the following table: Figure 13 The method comprises the following steps:

[0439] S1301, receiving an extended service request sent by a terminal. The extended service request is used to request to fall back to a 2G or 3G network to perform a specified service.

[0440] S1302, if the core network side network element is not connected to a 2G and 3G network, sending an extended service rejection response to the terminal.

[0441] S1303, sending a first request to the terminal, wherein the first request is used to request the terminal to re-perform network registration.

[0442] S1304, deleting the bearer information of the terminal.

[0443] The S1303 and S1304 can be executed in parallel or sequentially, and the embodiment of the present application does not make a specific limitation.

[0444] The method for recovering a service bearer provided by the embodiment of the present application, when the core network side network element cannot fall back the terminal to a 2G / 3G network to perform a specified service, can delete the bearer information of the terminal synchronously when sending an extended service rejection response to the terminal, and send a first request to the terminal, so that the terminal can re-perform network registration in time after receiving the first request. During the process of re-performing network registration by the terminal, the core network side network element can record the correct bearer information of the terminal again, so that the core network side network element can successfully establish a bearer of the specified service of IMS based on the correct bearer information of the terminal after the terminal re-sends a PDN establishment request or a PDU establishment request, and the terminal can obtain the bearer of the specified service of IMS. It can be seen that the embodiment of the present application can recover in time when the bearer of the specified service of IMS cannot be established, thereby improving the success rate of the UE requesting the specified service of IMS and reducing the security risk of communication interruption.

[0445] In the embodiment of the present application, in a 4G scenario, the core network side network element in the above Figure 13 is an MME, and after the core network side network element sends a first request to the terminal in the above S1304, the core network side network element can further execute the following steps to delete the bearer information of the terminal recorded in other core network side network elements:

[0446] Step one, sending a first session deletion request to a serving GW, wherein the first session deletion request is used to request the serving GW to delete the EPS bearer context information of the terminal.

[0447] Step two, receiving a first session deletion response reply from the serving GW.

[0448] Step three, sending a detach indication to the SGSN, wherein the detach indication is used to instruct the SGSN to notify the serving GW to delete the PDP context of the terminal and to notify the PDN GW to release the EPS bearer of the terminal.

[0449] In the embodiments of the present application, in the 4G scenario, the first request is a detach request, and the detach request includes a detach type field, wherein the detach type included in the detach type field is reattach required.

[0450] In the embodiments of the present application, in the 5G scenario, the core network side network element in the above-mentioned Figure 13 In the embodiments of the present application, in the 5G scenario, the core network side network element in the above-mentioned

[0451] Step 1, sending a subscription cancellation request to the UDM, wherein the subscription cancellation request is used to request to delete the connection information of the PDU session of the terminal.

[0452] Step 2, sending a PDU session release request to the SMF, wherein the PDU session release request is used to request to release the PDU session of the terminal, so that the SMF releases the PDU session of the terminal, and notifies the UPF to release the N4 session of the terminal, notifies the PCF to delete the SM policy of the terminal, and notifies the UDM to delete the subscriber data and context management data of the terminal.

[0453] Step 3, sending an AM policy association termination request to the PCF, wherein the AM policy association termination request is used to request to delete the AM policy association information of the terminal.

[0454] Step 4, sending a UE policy association termination request to the PCF, wherein the UE policy association termination request is used to request to delete the UE policy association information of the terminal.

[0455] Step 5, sending a connection release request to the base station, wherein the connection release request is used to request to delete the RM context of the terminal.

[0456] In the embodiments of the present application, in the 5G scenario, the first request is a deregistration request, and the deregistration request includes a deregistration type field, wherein the deregistration type included in the deregistration type field is re-registration required.

[0457] The specific implementation manner of the steps performed by each device in the method for resuming the service bearer provided by the embodiments of the present application can refer to the related description in the above-mentioned system for resuming the service bearer, which will not be described here again.

[0458] Based on the same inventive concept, corresponding to the method embodiments described above, the embodiments of the present application also provide a device for restoring a service bearer, applied to a core network side network element, such as an MME shown in the figure, which comprises a receiving module 1401, a sending module 1402 and a deleting module 1403. Figure 14

[0459] The receiving module 1401 is configured to receive an extended service request sent by a terminal, the extended service request being used for requesting to fall back to a 2G or 3G network to perform a specified service.

[0460] The sending module 1402 is configured to send an extended service rejection response to the terminal if the core network side network element is not connected to the 2G and 3G networks.

[0461] The sending module 1402 is further configured to send a first request to the terminal, the first request being used for requesting the terminal to perform network registration again.

[0462] The deleting module 1403 is configured to delete the bearer information of the terminal.

[0463] In some embodiments of the present application, the core network side network element is an MME,

[0464] The sending module 1402 is further configured to send a first session deletion request to a serving GW after deleting the bearer information of the terminal, the first session deletion request being used for requesting the serving GW to delete the EPS bearer context information of the terminal.

[0465] The receiving module 1401 is further configured to receive a first session deletion response returned by the serving GW.

[0466] The sending module 1402 is further configured to send a detach indication to an SGSN, the detach indication being used for instructing the SGSN to notify the serving GW to delete the PDP context of the terminal and to notify a PDN GW to release the EPS bearer of the terminal.

[0467] In some embodiments of the present application, the core network side network element is an AMF, and the sending module 1402 is further configured to:

[0468] After deleting the bearer information of the terminal, send an unsubscription request to a UDM, the unsubscription request being used for requesting to delete the connection information of a PDU session of the terminal.

[0469] Send a PDU session release request to an SMF, the PDU session release request being used for requesting to release the PDU session of the terminal, so that the SMF releases the PDU session of the terminal, notifies a UPF to release an N4 session of the terminal, notifies a PCF to delete an SM policy of the terminal, and notifies a UDM to delete subscriber data and context management data of the terminal.

[0470] ​sending an AM policy association termination request to the PCF, the AM policy association termination request being used for requesting to delete the AM policy association information of the terminal;

[0471] sending a UE policy association termination request to the PCF, the UE policy association termination request being used for requesting to delete the UE policy association information of the terminal;

[0472] sending a connection release request to the base station, the connection release request being used for requesting to delete the RM context of the terminal.

[0473] In some embodiments of the present application, the first request is a detach request, and the detach request comprises a detach type field, wherein the detach type included in the detach type field is re-attach required.

[0474] In some embodiments of the present application, the first request is a de-registration request, and the de-registration request comprises a de-registration type field, wherein the de-registration type included in the de-registration type field is re-registration required.

[0475] The embodiments of the present application further provide a core network side network element, such as Figure 15 As shown in the figure, the core network side network element comprises a processor 1501, a communication interface 1502, a memory 1503 and a communication bus 1504, wherein the processor 1501, the communication interface 1502 and the memory 1503 complete mutual communication through the communication bus 1504,

[0476] The memory 1503 is used for storing a computer program.

[0477] The processor 1501 is used for executing the program stored in the memory 1503, and realizes the following steps:

[0478] receiving an extended service request sent by the terminal, the extended service request being used for requesting to fall back to a 2G or 3G network to perform a specified service;

[0479] if the core network side network element does not interface with the 2G and 3G networks, sending an extended service rejection response to the terminal;

[0480] sending a first request to the terminal, the first request being used for requesting the terminal to re-perform network registration;

[0481] deleting the bearer information of the terminal.

[0482] In some embodiments of the present application, the core network side network element is an MME, and the core network side network element is further used for realizing the following steps:

[0483] after sending the first request to the terminal, sending a first session deletion request to a serving GW, the first session deletion request being used for requesting the serving GW to delete the EPS bearer context information of the terminal;

[0484] receiving a first delete session response from the serving GW in reply to the first delete session request;

[0485] sending a detach indication to the SGSN, the detach indication indicating the SGSN to inform the serving GW to delete a PDP context of the terminal and to inform the PDN GW to release an EPS bearer of the terminal.

[0486] In some embodiments of the present application, the core network side network element is an AMF, and the core network side network element is further configured to implement the following steps:

[0487] after sending the first request to the terminal, sending a cancel subscription request to the UDM, the cancel subscription request being used to request to delete connection information of a PDU session of the terminal;

[0488] sending a PDU session release request to the SMF, the PDU session release request being used to request to release a PDU session of the terminal, so that the SMF releases the PDU session of the terminal, and notifies a UPF to release an N4 session of the terminal, notifies a PCF to delete an SM policy of the terminal, and notifies a UDM to delete subscriber data and context management data of the terminal;

[0489] sending an AM policy association termination request to the PCF, the AM policy association termination request being used to request to delete AM policy association information of a PDU session of the terminal;

[0490] sending a UE policy association termination request to the PCF, the UE policy association termination request being used to request to delete UE policy association information of the terminal;

[0491] sending a connection release request to the base station, the connection release request being used to request to delete an RM context of the terminal.

[0492] In some embodiments of the present application, the first request is a detach request, and the detach request includes a detach type field, and a detach type included in the detach type field is a type that requires reattachment.

[0493] In some embodiments of the present application, the first request is a deregistration request, and the deregistration request includes a deregistration type field, and a deregistration type included in the deregistration type field is a type that requires re-registration.

[0494] The communication bus mentioned by the core network side network element can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. The communication bus can be divided into an address bus, a data bus, a control bus, etc. For the convenience of representation, only one thick line is used in the figure, but it does not mean that there is only one bus or only one type of bus.

[0495] The communication interface is used for communication between the core network side network element and other devices.

[0496] The memory can include a Random Access Memory (RAM) and can also include a Non-Volatile Memory (NVM), for example, at least one disk memory. Optionally, the memory can also be at least one storage device located away from the aforementioned processor.

[0497] The processor mentioned above can be a general-purpose processor, including a Central Processing Unit (CPU), a Network Processor (NP), etc.; can also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA) or other programmable logic device, a discrete gate or transistor logic device, a discrete hardware component.

[0498] In another embodiment provided in the present application, a computer readable storage medium is also provided, and the computer readable storage medium stores a computer program. The computer program is executed by a processor to implement the steps of any of the above methods for resuming a service bearer.

[0499] In another embodiment provided in the present application, a computer program product containing instructions is also provided, and when the computer program product is run on a computer, the computer is caused to execute the method for resuming a service bearer in any of the above embodiments.

[0500] In the embodiments described above, all or some of the steps can be implemented by hardware, software, firmware or any combination thereof. When implemented by software, all or some of the steps can be implemented in the form of one or more computer programs or program elements. The computer programs reside (at least temporarily) in a memory of a computer during execution. The memory can be a RAM memory, a flash memory, a ROM memory, an EPROM memory, or any other suitable memory. The memory can be integral to or separate from the computer. The computer programs can be written in any suitable programming language, such as C, C++, Java, Visual Basic, etc. The computer programs can be written in assembly or machine language, if desired. The computer programs can be distributed over network coupled file servers, or can be distributed by any other suitable means.

[0501] It is to be noted that the terms such as first and second, etc., are used herein merely to differentiate one entity or action from another, and do not necessarily require or imply any such actual relationship or order between such entities or actions. Also, the terms "comprising", "containing", or any other similar term are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not necessarily contain only those elements, but can contain other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0502] Each of the embodiments in the present specification is described in a related manner, and the same or similar parts among the embodiments can be referred to each other. Each of the embodiments focuses on the difference from other embodiments. In particular, for the device embodiments, since they are substantially similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the part of the description of the method embodiments.

[0503] The above merely provides the preferred embodiment of the present application, and not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A system for recovering a service bearer, characterized by, The system comprises a terminal and a core network side network element; The terminal is configured to send an extended service request to the MME, wherein the extended service request is used to request to fall back to a 2G or 3G network to perform a specified service; The core network side network element is configured to receive the extended service request, and if the core network side network element is not connected to the 2G and 3G networks, send an extended service rejection response to the terminal, send a first request to the terminal, wherein the first request is used to request the terminal to re-perform network registration, and delete bearer information of the terminal.

2. The system of claim 1, wherein, The core network side network element is a mobility management entity (MME), and the system further comprises a serving gateway (serving GW), a serving general packet radio service (GPRS) support node (SGSN), a packet data network gateway (PDN GW) and a policy and charging rules function (PCRF) to which the terminal is registered; The MME is further configured to send a first session deletion request to the serving GW; The serving GW is configured to receive the first session deletion request, delete EPS bearer context information of the terminal, and send a first session deletion response to the MME; The MME is further configured to send a detachment indication to the SGSN; The SGSN is configured to receive the detachment indication, send a second session deletion request to the serving GW; The serving GW is further configured to receive the second session deletion request, and delete PDP context of the terminal; The serving GW is further configured to send a third session deletion request to the PDN GW; The PDN GW is configured to release the EPS bearer of the terminal, and send a third session deletion response to the serving GW; The PDN GW is further configured to notify the PCRF that the PDN GW has released the EPS bearer of the terminal; The serving GW is further configured to send a second session deletion response to the SGSN; The SGSN is further configured to send a detachment response to the MME.

3. The system of claim 1, wherein, The core network side network element is an access and mobility management function (AMF), and the system further comprises a unified data management function (UDM), a session management function (SMF), a user plane function (UPF), a policy control function (PCF) and a base station to which the terminal is registered; The AMF is further configured to send an unsubscription request to the UDM; The UDM is configured to receive the unsubscription request, and delete connection information of a PDU session of the terminal; The AMF is further configured to send a PDU session release request to the SMF; The SMF is configured to receive the PDU session release request, release the PDU session of the terminal, and send an N4 session release request to the UPF; The UPF is configured to receive the N4 session release request, release an N4 session of the terminal, and send an N4 session release response to the SMF; The SMF is further configured to send a PDU session release response to the AMF; The SMF is further configured to send an SM policy association termination request to the PCF; The PCF is configured to delete the SM policy of the terminal, and send an SM policy association termination response to the SMF. The SMF is further configured to send a subscriber data unsubscription request to the UDM. The UDM is further configured to delete the subscriber data of the terminal, and send a subscriber data unsubscription response to the SMF. The SMF is further configured to send a terminal context management deregistration request to the UDM. The UDM is further configured to delete the context management data of the terminal, and send a terminal context management deregistration response to the SMF. The AMF is further configured to send an AM policy association termination request to the PCF. The PCF is further configured to receive the AM policy association termination request, delete the AM policy association information of the terminal, and send an AM policy association termination response to the AMF. The AMF is further configured to send a UE policy association termination request to the PCF. The PCF is further configured to receive the UE policy association termination request, delete the UE policy association information of the terminal, and send a UE policy association termination response to the AMF. The AMF is further configured to send a connection release request to the base station. The base station is configured to receive the connection release request, delete the registration management (RM) context of the terminal, and send a connection release response to the AMF.

4. The system of claim 2, wherein, The first request is a detach request, and the detach request comprises a detach type field, wherein the detach type field comprises a detach type, and the detach type is re-attachment required.

5. The system of claim 3, wherein, The first request is a deregistration request, and the deregistration request comprises a deregistration type field, wherein the deregistration type field comprises a deregistration type, and the deregistration type is re-registration required.

6. A method of recovering a service bearer, characterized by, The method is applied to a core network side network element, and the method comprises the following steps: receiving an extended service request sent by a terminal, wherein the extended service request is used to request to fall back to a 2G or 3G network to perform a specified service; if the core network side network element is not connected to a 2G and 3G network, sending an extended service rejection response to the terminal; sending a first request to the terminal, wherein the first request is used to request the terminal to re-perform network registration; deleting bearer information of the terminal.

7. The method of claim 6, wherein, The core network side network element is an MME, and after the step of sending the first request to the terminal, the method further comprises the following steps: sending a first session deletion request to a serving GW, wherein the first session deletion request is used to request the serving GW to delete EPS bearer context information of the terminal; receiving a first session deletion response returned by the serving GW; sending a detach indication to an SGSN, wherein the detach indication is used to instruct the SGSN to inform a serving GW to delete a PDP context of the terminal, and to inform a PDN GW to release an EPS bearer of the terminal.

8. The method of claim 6, wherein, The core network side network element is an AMF, and after the step of sending the first request to the terminal, the method further comprises the following steps: sending an unsubscription request to the UDM, wherein the unsubscription request is used to request to delete connection information of a PDU session of the terminal; sending a PDU session release request to the SMF, the PDU session release request being used to request to release a PDU session of the terminal, so that the SMF releases the PDU session of the terminal, and notifies a UPF to release an N4 session of the terminal, notifies a PCF to delete SM policy of the terminal, and notifies a UDM to delete subscriber data and context management data of the terminal; sending an AM policy association termination request to the PCF, the AM policy association termination request being used to request to delete AM policy association information of the terminal; sending a UE policy association termination request to the PCF, the UE policy association termination request being used to request to delete UE policy association information of the terminal; sending a connection release request to the base station, the connection release request being used to request to delete an RM context of the terminal.

9. The method of claim 7, wherein, The first request is a detach request, and the detach request includes a detach type field, and a detach type included in the detach type field is a re-attach required type.

10. The method of claim 8, wherein, The first request is a de-registration request, and the de-registration request includes a de-registration type field, and a de-registration type included in the de-registration type field is a re-registration required type.

11. An apparatus for recovering a service bearer, the apparatus comprising: The device is applied to a core network side network element, and the device includes: a receiving module, configured to receive an extended service request sent by a terminal, the extended service request being used to request to fall back to a 2G or 3G network to perform a specified service; a sending module, configured to send an extended service rejection response to the terminal if the core network side network element is not connected to the 2G and 3G networks; the sending module is further configured to send a first request to the terminal, the first request being used to request the terminal to re-perform network registration; a deleting module, configured to delete bearer information of the terminal.

12. A core network side network element, characterized by, The device includes a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory complete mutual communication through the communication bus; the memory is used to store a computer program; the processor is used to execute the program stored on the memory, and the following steps are implemented: receiving an extended service request sent by a terminal, the extended service request being used to request to fall back to a 2G or 3G network to perform a specified service; if the core network side network element is not connected to the 2G and 3G networks, sending an extended service rejection response to the terminal; sending a first request to the terminal, the first request being used to request the terminal to re-perform network registration; deleting bearer information of the terminal.

13. The core network side network element according to claim 12, c h a r a c t e r i z e d b y The core network side network element is an MME, and the core network side network element is further configured to implement the following steps: after the first request is sent to the terminal, sending a first session deletion request to a serving GW, the first session deletion request being used to request the serving GW to delete EPS bearer context information of the terminal; receiving a first session deletion response returned by the serving GW; sending a detach indication to an SGSN, the detach indication being used to instruct the SGSN to notify a serving GW to delete a PDP context of the terminal, and notify a PDN GW to release an EPS bearer of the terminal.

14. The core network side network element according to claim 12, c h a r a c t e r i z e d b y The core network side network element is an AMF, and the core network side network element is further configured to implement the following steps: After the first request is sent to the terminal, a cancel subscription request is sent to the UDM, and the cancel subscription request is used to request to delete the connection information of the PDU session of the terminal; A PDU session release request is sent to the SMF, and the PDU session release request is used to request to release the PDU session of the terminal, so that the SMF releases the PDU session of the terminal, notifies the UPF to release the N4 session of the terminal, notifies the PCF to delete the SM policy of the terminal, and notifies the UDM to delete the subscriber data and context management data of the terminal; An AM policy association termination request is sent to the PCF, and the AM policy association termination request is used to request to delete the AM policy association information of the PDU session of the terminal; A UE policy association termination request is sent to the PCF, and the UE policy association termination request is used to request to delete the UE policy association information of the terminal; A connection release request is sent to the base station, and the connection release request is used to request to delete the RM context of the terminal.

15. The core network side network element according to claim 13, c h a r a c t e r i z e d b y The first request is a detach request, and the detach request includes a detach type field, and the detach type field includes a detach type that needs to be reattached.

16. The core network side network element according to claim 14, c h a r a c t e r i z e d b y The first request is a deregistration request, and the deregistration request includes a deregistration type field, and the deregistration type field includes a deregistration type that needs to be re-registered.

17. A computer-readable storage medium, characterized in that, The computer readable storage medium stores a computer program, and the computer program is executed by the processor to implement the steps of the method of any one of claims 6-10.

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