CN112911658B

CN112911658B - Communication method and device

Info

Publication number: CN112911658B
Application number: CN201911229149.6A
Authority: CN
Inventors: 吴鹏程
Original assignee: Datang Mobile Communications Equipment Co Ltd
Current assignee: Datang Mobile Communications Equipment Co Ltd
Priority date: 2019-12-04
Filing date: 2019-12-04
Publication date: 2022-03-29
Anticipated expiration: 2039-12-04
Also published as: CN112911658A

Abstract

The invention provides a communication method and a communication device, which are used for solving the problem of failure in switching from a 5G network to a 4G network. When the terminal equipment is switched from a first communication network to a second communication network, a first mobility management network element receives context information sent by a second mobility management network element, wherein the first mobility management network element belongs to the second communication network, and the second mobility management network element belongs to the first communication network; and when determining that the context information does not include the session context of the terminal equipment, the first mobility management network element sends a first indication to the terminal equipment, wherein the first indication is used for indicating the terminal equipment to initiate a Public Data Network (PDN) connection process.

Description

Communication method and device

Technical Field

The present invention relates to the field of communications technologies, and in particular, to a communication method and apparatus.

Background

With the development of the fifth generation mobile communication (5G) technology, users of the 5G network are increasing. Therefore, a terminal Equipment (UE) may often switch between the coverage of the 5G network and the coverage of the 4G network. The registration process of the fourth generation mobile communication (4G) is different from the registration process of the 5G, and the 4G has an Always Online "function, that is, a default bearer with a fixed data rate is established for the user in the registration process of the 4G network, so as to ensure the basic service requirement.

When the UE is handed over from the 5G network to the 4G network, if the UE does not establish a session in the 5G network, a handover failure may result. That is, even if the UE is a legitimate user, not all of the UEs can successfully hand into the 4G network after successful registration in the 5G network. Therefore, an effective scheme for smooth switching from 5G to 4G network is urgently needed.

Disclosure of Invention

The invention provides a communication method and a communication device, which are used for solving the problem of the conventional switching failure.

In a first aspect, an embodiment of the present invention provides a communication method, including: when the terminal equipment is switched from a first communication network to a second communication network, a first mobility management network element receives context information sent by a second mobility management network element, wherein the first mobility management network element belongs to the second communication network, and the second mobility management network element belongs to the first communication network; and when determining that the context information does not include the session context of the terminal equipment, the first mobility management network element sends a first indication to the terminal equipment, wherein the first indication is used for indicating the terminal equipment to initiate a Public Data Network (PDN) connection process.

According to the method, the PDN connection process is triggered by indicating the terminal equipment, so that the 5G network can be switched to the 4G network under the condition that a session is not established in the 5G network, and the mutual switching process of the terminal equipment between the 4G network and the 5G network is perfected.

In an optional implementation manner, the first mobility management network element is a mobility management entity MME, and the second mobility management network element is an access and mobility management function AMF.

In a second aspect, an embodiment of the present invention provides a communication method, including: when terminal equipment is switched from a first communication network to a second communication network, the terminal equipment receives a first instruction sent by a first mobility management network element, wherein the first instruction is used for instructing the terminal equipment to initiate a Public Data Network (PDN) connection process, and the first mobility management network element belongs to the first communication network; and the terminal equipment triggers a PDN connection process according to the first indication.

In an optional implementation manner, when the terminal device is handed over from the first communication network to the second communication network, the method further includes: the terminal equipment sends a tracking area updating request message to the first mobility management network element;

the method for receiving the first indication sent by the first mobility management network element by the terminal device includes:

and the terminal equipment receives a tracking area update receiving message sent by a first mobility management network element, wherein the tracking area update receiving message carries the first indication.

In the scheme, the first indication is carried by the tracking area update receiving message, no signaling message needs to be added, and resources are saved.

In an optional implementation manner, the triggering, by the terminal device, the PDN connection procedure according to the first indication includes:

and after the terminal equipment finishes sending a tracking area updating finishing message to the first mobility management network element, the terminal equipment triggers a PDN connection process according to a first indication.

In a third aspect, an embodiment of the present invention provides a communication method, including: when the terminal equipment is switched from a first communication network to a second communication network, a second mobility management network element receives a context request message sent by the first mobility management network element; the first mobility management network element belongs to a second communication network, and the second mobility management network element belongs to a first communication network; and when determining that the session of the terminal device is not established in the first communication network, the second mobility management network element sends a context response message to the first mobility management network element, where the context response message does not carry the session context of the terminal device.

In the method, the second mobility management network element determines whether the terminal device establishes a session in the first communication network, and the PDU session context request is not triggered any more when the session is not established. And directly responding the session context, wherein the context response message does not carry the session context of the terminal equipment.

In an optional implementation manner, the method further includes:

and when determining that the terminal equipment establishes a session in the first communication network, the second mobility management network element triggers a process of acquiring a session context to a session management network element.

In a fourth aspect, an embodiment of the present invention provides a communication apparatus, which is applied to a first mobility management network element, where the communication apparatus includes:

a receiving unit, configured to receive context information sent by a second mobility management network element when a terminal device is switched from a first communication network to a second communication network, where the first mobility management network element belongs to the second communication network and the second mobility management network element belongs to the first communication network;

a processing unit, configured to determine that a session context of the terminal device is not included in the context information;

a sending unit, configured to send a first instruction to the UE when the processing unit determines that the context information does not include the session context of the terminal device, where the first instruction is used to instruct the terminal device to initiate a public data network PDN connection procedure.

In a fifth aspect, an embodiment of the present invention provides a communication apparatus, which is applied to a terminal device, where the communication apparatus includes:

a receiving unit, configured to receive a first instruction sent by a first mobility management network element when the terminal device is switched from a first communication network to a second communication network, where the first instruction is used to instruct the terminal device to initiate a public data network PDN connection procedure, and the first mobility management network element belongs to the first communication network;

and the processing unit is used for triggering the PDN connection process according to the first indication.

In an optional implementation manner, the communication apparatus further includes:

a sending unit, configured to send a tracking area update request message to the first mobility management network element when the terminal device is switched from a first communication network to a second communication network;

the receiving unit is specifically configured to receive a tracking area update accept message sent by a first mobility management network element, where the tracking area update accept message carries the first indication.

In an optional implementation manner, the processing unit is specifically configured to trigger a PDN connection procedure according to a first indication after the tracking area update completion message is sent to the first mobility management network element.

In a sixth aspect, an embodiment of the present invention provides a communications apparatus, which is applied to a second mobility management network element, and includes:

a receiving unit, configured to receive, by a second mobility management network element, a context request message sent by a first mobility management network element when a terminal device is switched from a first communication network to a second communication network; the first mobility management network element belongs to a second communication network, and the second mobility management network element belongs to a first communication network;

a processing unit configured to determine that the terminal device does not establish a session in the first communication network;

a sending unit, configured to send, to the MME, a context response message when the processing unit determines that the session of the terminal device is not established in the first communication network, where the context response message does not carry a session context of the terminal device.

In an optional implementation manner, the processing unit is further configured to trigger a procedure of acquiring a session context to a session management network element when it is determined that the terminal device establishes a session in the first communication network.

In a seventh aspect, an embodiment of the present invention provides a communications apparatus, where the apparatus may be applied to a first mobility management network element, and the apparatus includes a memory and a processor;

a memory for storing program instructions;

and the processor is used for calling the program instructions stored in the memory and executing the method of any implementation mode of the first aspect according to the obtained program.

In an eighth aspect, an embodiment of the present invention provides a communication apparatus, where the apparatus may be applied to a terminal device, where the apparatus includes a memory and a processor;

a memory for storing program instructions;

and the processor is used for calling the program instructions stored in the memory and executing the method of any implementation mode of the second aspect according to the obtained program.

In a ninth aspect, an embodiment of the present invention provides a communications apparatus, where the apparatus is applicable to a second mobility management network element, and the apparatus includes a memory and a processor;

a memory for storing program instructions;

and the processor is used for calling the program instructions stored in the memory and executing the method of any implementation mode of the third aspect according to the obtained program.

In a tenth aspect, an embodiment of the present invention provides a computer-readable storage medium, which stores computer instructions that, when executed on a computer, cause the computer to perform the above method.

In addition, for technical effects brought by any one implementation manner of the fourth aspect to the tenth aspect, reference may be made to technical effects brought by different implementation manners of the first aspect to the third aspect, and details are not described here.

Drawings

Fig. 1 is a schematic structural diagram of a communication system according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of another communication system according to an embodiment of the present invention;

fig. 3 is a flowchart of a communication method according to an embodiment of the present invention;

fig. 4A is a schematic diagram of another communication method according to an embodiment of the present invention;

fig. 4B is a schematic diagram of another communication method according to an embodiment of the present invention;

fig. 5 is a schematic diagram of a PDN connection procedure according to an embodiment of the present invention;

fig. 6 is a diagram illustrating a communication device 600 according to an embodiment of the invention;

fig. 7 is a diagram of a communication device 700 according to an embodiment of the invention;

fig. 8 is a diagram of a communication device 800 according to an embodiment of the invention;

fig. 9 is a schematic diagram of a communication device 900 according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail with reference to the accompanying drawings, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The application scenario described in the embodiment of the present invention is for more clearly illustrating the technical solution of the embodiment of the present invention, and does not form a limitation on the technical solution provided in the embodiment of the present invention, and it can be known by a person skilled in the art that with the occurrence of a new application scenario, the technical solution provided in the embodiment of the present invention is also applicable to similar technical problems. In the description of the present invention, the term "plurality" means two or more unless otherwise specified.

Fig. 1 illustrates a communication system architecture, it should be understood that the embodiments of the present invention are not limited to the system shown in fig. 1, and moreover, the apparatus in fig. 1 may be hardware, or may be a functionally divided software, or a combination of the two. As shown in fig. 1, a system architecture provided in the embodiment of the present invention includes a terminal device, a first base station, a second base station, a first mobility management network element, a second mobility management network element, a session management network element, a user plane network element, and a Data Network (DN). The first base station, the first mobility management network element and the first session management network element belong to a second communication network. The second base station, the second mobility management network element and the second session management network element belong to the first communication network. For example, the first communication network may be a 5G network, the second communication network may be a 4G network, a 3G network, or the like. The terminal device communicates with the DN through a base station (first base station or second base station) and a user plane network element. The first mobility management network element and the second mobility management network element may be connected via an N26 interface. The interface name is only an example, and the embodiment of the present invention is not limited to this.

A Terminal device (UE), also called a Terminal device, a Terminal, a Mobile Station (MS), a Mobile Terminal (MT), etc., is a device that provides voice and/or data connectivity to a User, for example, a handheld device, a vehicle-mounted device, etc. with a wireless connection function. Currently, some examples of terminals are: a Mobile phone (Mobile phone), a tablet computer, a notebook computer, a palm computer, a Mobile Internet Device (MID), a wearable Device, a Virtual Reality (VR) Device, an Augmented Reality (AR) Device, a wireless terminal in Industrial Control (Industrial Control), a wireless terminal in unmanned driving (self driving), a wireless terminal in remote surgery (remote medical supply), a wireless terminal in smart grid (smart grid), a wireless terminal in transportation safety, a wireless terminal in city (smart city), a wireless terminal in smart home (smart home), and the like.

The base station related in the embodiment of the present invention may also be referred to as AN Access Node (Access Node, abbreviated as AN) to provide a wireless Access service for the terminal. The first Base Station may specifically be a Base Transceiver Station (BTS) in a Global System for Mobile communications (GSM) System or a Code Division Multiple Access (CDMA) System, a Base Station (NodeB) in a Wideband Code Division Multiple Access (WCDMA) System, a small Base Station device, a wireless Access Node (WiFi AP), a wireless Access Microwave Access Base Station (WiMAX BS), and the like, and may also be an evolved Node B (eNB or eNodeB) in an LTE System. The second base station may be a base station equipment (gNB) in a 5G network, which is not limited in the present invention.

Take the first communication network as a 5G network and the second communication network as a 4G network as an example. Referring to fig. 2, a diagram of the system architecture after 4G and 5G are fused is shown. The second Mobility Management network element may be an Access and Mobility Management entity (AMF) in 5G. The first Mobility Management network element may be a Mobility Management Entity (MME), or a control plane function (SGW-C) of a Serving GateWay (SGW) in 4G and a control function after the MME is merged. And the AMF is responsible for UE access and mobility management, NAS message routing, SMF selection and the like. The AMF may be used as an intermediate network element to transmit a session management message between the UE and a Session Management Function (SMF). In the embodiment of the present invention, the first mobility management network element is an MME, and the second mobility management network element is an AMF.

And the session management network element is responsible for forwarding path management, and if a message forwarding strategy is issued to the user plane network element, the user plane network element is instructed to process and forward the message according to the message forwarding strategy. The session management network element may be a Session Management Function (SMF) in 5G, and is responsible for session management, such as session creation/modification/deletion, UPF selection, and allocation and management of user plane tunnel information. The session management network element may also be a control plane function (SGW-C) of a Serving GateWay (SGW) in 4G or a control plane function (PGW-C) of a Packet Data Network (PDN) GateWay (GateWay way, GW), and the session management network element may also be all or part of a control function formed after the SMF and PGW-C network elements are fused, for example, see fig. 2.

The user plane network element may be a user plane function entity (UPF) in the 5G architecture, and the UPF is responsible for message processing and forwarding. The user plane network element may also be a forwarding plane function (PGW-U) of the PGW. The user plane network element may be all or part of the function after the fusion of the PGW-U and the UPF, such as shown in fig. 2.

The system architecture may further include a User Data Management entity (UDM), or a Home Subscriber Server (HSS), or include all or part of the functions of the UDM and the HSS after the UDM and the HSS are merged, for example, as shown in fig. 2.

The system architecture may further include a Policy Control Function (PCF) responsible for Policy Control decisions and flow-based charging Control.

The embodiment of the invention provides a communication method and a communication device, which are used for solving the problem that the existing 5G network is switched to a 4G network and the switching fails. The scheme provided by the embodiment of the invention is described in detail in the following with reference to the attached drawings.

Referring to fig. 3, a communication method provided in an embodiment of the present invention is described with reference to interaction among a terminal device, a first mobility management network element, and a second mobility management network element.

S301, when the terminal device is switched from the first communication network to the second communication network, the first mobility management network element sends a context request message to the second mobility management network element.

The first mobility management network element belongs to the second communication network, and the second mobility management network element belongs to the first communication network.

S302, the second mobility management network element receives the context request message sent by the second mobility management network element, and when determining that the terminal device does not establish a session in the first communication network, the second mobility management network element sends a context response message to the first mobility management network element, where the context response message carries context information, and the context information does not include a session context of the terminal device.

S303, when determining that the context information does not include the session context of the terminal device, the first mobility management network element sends a first instruction to the terminal device, where the first instruction is used to instruct the terminal device to initiate a Public Data Network (PDN) connection procedure.

And S304, after receiving the first instruction sent by the first mobile management network element, the terminal equipment triggers a PDN connection process according to the first instruction.

The following takes the first communication network as a 5G network, the second communication network as a 4G network, the first mobility management network element as an MME, and the second mobility management network element as an AMF as an example, and details the scheme provided by the embodiment of the present invention. Referring to fig. 4A and 4B, a terminal device is taken as an example UE. Taking the session management network element as PGW-C/SMF as an example, and taking the user plane network element as PGW-U/UPF as an example. After the UE completes registration on the 5G network, when the UE moves from the base station gNB of 5G to the coverage of the base station eNB of 4G, a reselection procedure from 5GS to an Evolved Packet System (EPS) is performed.

S401, the UE triggers a Tracking Area Update (TAU) procedure.

S402, UE triggers the tracking area updating process under 4G, and UE sends a tracking area updating Request (TAU Request) message to eNB.

S403, the eNB forwards a tracking area update Request (TAU Request) message to the MME. Optionally, the tracking area update Request (TAU Request) message may carry identification information of the UE, such as global Unique Temporary UE Identity (GUTI).

S404, the MME determines that the UE is a user registered in 5G according to the identification information of the UE, and sends a Context Request (Context Request) message to an AMF for managing the UE. The Context Request (Context Request) message may carry a TAU Request message.

And the AMF verifies the integrity of the TAU request message, judges whether the UE establishes a Session (Session) in the 5G network, and enters different processing flows according to the judgment result.

In case 1, if the integrity check of the TAU request message by the AMF fails, the security context and bearer information are not transferred to the MME. A context response message may be sent directly to the MME, in which a cause value for the integrity verification failure may be indicated. After receiving the context response message, the MME sends a TAU Reject (Reject) message to the UE, and the procedure ends.

In case 2, if the integrity check of the TAU request message by the AMF is successful and the UE session has been established in the 5G network, the flow performed is as shown in fig. 4A.

Case 3, if the integrity check of the AMF on the TAU request message is successful and no UE session is established in the 5G network. The AMF delivers only the security context and not the bearer context to the MME. The specific subsequent flow is shown in fig. 4B.

Referring to FIG. 4A:

s405a, the AMF verifies that the integrity of the TAU request message is successful and a session is established in the 5G network, and sends a PDU session context request (e.g., Nsmf _ pdusessocontextrequest) message to the PGW-C/SMF.

Optionally, if PGW-U tunnel information is allocated by the PGW-U/UPF, the PGW-C/SMF may send an N4 session modification request (N4 session modification) to the PGW-U/UPF, establish a tunnel for each EPS bearer, and the PGW-U/UPF provides the PGW-U tunnel information of each EPS bearer to the PGW-C/SMF.

S406a, for the PDU session of the anchor UPF, the PGW-C/SMF returns a PDU session context response (such as Nsmf _ pdussioncontextrequest) message. The PDU session context response message may contain the mapped EPS bearer context. For example, the EPS bearer context includes one or more of PGW-C control plane tunnel information of a PDN connection corresponding to the PDU session, an EPS Bearer Identity (EBI) of each EPS bearer, PGW-U tunnel information of each EPS bearer, and EPS QoS parameters.

S407a, the AMF replies to the MME with a Context Response (Context Response) message. The context response message carries the session context and the security context.

S408a, the MME may choose to initiate an authentication/security procedure.

S409a, the MME replies a Context Ack (Context Ack) message to the AMF.

S410a, the MME initiates a bearer (or Session) establishment procedure, and the MME sends a create Session Request (credit Session Request) message to the SGW.

S411a, the SGW sends a modify bearer request (modify bearer request) message to the PGW-C/SMF.

S412a, the PGW-C/SMF and the PGW-U/UPF execute the N4 session modification flow.

S413a, the PGW-C/SMF carries a modification response (modify bearer response) message to the SGW.

S414a, the SGW sends a create Session response (create Session response) message to the MME.

The above S410a-S414a are the procedures initiated by the MME and establishing the bearer with the PGW-C/SMF and the PGW-U/UPF.

S415a, the MME sends an Update Location Request (Update Location Request) message to the UDM/HSS.

S416a, the HSS/UDM sends a deregistration notification (numdm UECM deregistration) message to the AMF.

S417a, the AMF replies to the HSS/UDM with a data deregistration (Nudm _ SDM _ Unscubscribe) message.

S418a, the UDM/HSS sends an Update Location acknowledgement (Update Location ACK) to the AMF.

S419a, the MME replies to the UE with a TAU Accept (Accept) message.

S420a, the UE replies to the MME with a TAU Complete (Complete) message.

Alternatively, if some Quality of Service (QoS) flows of the EPS bearer are marked for deletion, the PGW-C/SMF initiates a bearer modification procedure to delete the Traffic Flow Template (TFT) filters corresponding to the set of packet filters in the QoS rules.

See fig. 4B for illustration:

s405b, the AMF verifies that the integrity of the TAU request message is successful and a session of the terminal device is not established in the 5G system, and returns a Context Response (Context Response) message to the MME. The context response message carries the context information, including the security context, but not including the session context.

S406b, the MME may choose to initiate authentication and security procedures.

At S407b, the MME replies to the AMF with a Context Ack message.

After executing S405b, the MME determines the received context response message after receiving the context response message. If the security context is carried but the Session context is not, the MME no longer sends a Create Session Request (Create Session Request) to the SGW to Create the Session.

S408b, the MME sends an Update Location Request (Update Location Request) message to the UDM/HSS.

S409b, the HSS/UDM sends a deregistration notification (numm _ UECM _ deregistration notification) message to the AMF.

S410b, the AMF replies to the HSS/UDM with a data deregistration (Nudm _ SDM _ Unscubscribe) message.

S411b, the UDM/HSS sends an Update Location acknowledgement (Update Location ACK) to the AMF.

S412b, the MME sends a tracking area update Accept (TAU Accept) message to the UE.

If in S405b, the AMF transferred the security context to the MME, but not the session context. A first indication, such as a Need to Target Procedure IE, needs to be carried in a tracking area update Accept (TAU Accept) message. The first indication is used for indicating the UE to trigger the PDN connection flow. For example, the value of the Need to Target Procedure IE is 1, which indicates the UE to trigger the PDN connection Procedure, and when the value of the Need to Target Procedure IE is 0, indicates the UE not to trigger the PDN connection Procedure. Or, when the value of the Need to Target Procedure IE is 1, instructing the UE to trigger the PDN connection Procedure, and when the tracking area update Accept (TAU Accept) message does not carry the Need to Target Procedure IE, instructing the UE not to trigger the PDN connection Procedure.

S413b, the UE replies to the tracking area update Complete (TAU Complete) message.

S414b, after the tracking area update procedure is completed according to the first indication transmitted by the MME, the UE triggers a PDN connection procedure (UE requested PDN connectivity procedure) by sending a PDN connection Request message to the MME. Therefore, a default bearer is established, and the always Online (always Online) function required by 4G is achieved. The steps ensure that a legal user can smoothly switch from 5G to 4G without position updating failure under the existing protocol rule even if the Session is not established in 5G originally in the process of switching from 5G to 4G.

Optionally, the tracking area update Accept (TAU Accept) message may carry one or more of the information shown in table 1 on the basis that the new to Target Procedure IE may be carried.

TABLE 1

As an example, the new to Target Procedure may be used to indicate initiation of other different procedures, in addition to the PDN connection Procedure, in other different procedures, as described in the following examples:

1) the UE triggers a PDN connection procedure (UE requested PDN connection capability procedure);

2) an Attach request (UE originating Attach request) initiated by the UE;

3) UE initiates detachment (UE orienting detach);

4) a Service request (UE originating Service request) initiated by the UE;

5) a UE originating a location area update procedure (UE originating Tracking area update procedure);

6) UE initiated request to allocate dedicated bearer resource (UE originating request of the allocation of a dedicated bearer resource).

The PDN connection procedure is described in detail below with reference to fig. 5.

S501, the UE sends a PDN connection Request (PDN Connectivity Request) message to the MME. The PDN connection Request message may include one or more of an Access Point Name (Access Point Name APN), a PDN Type (Type), a Protocol Configuration option (Protocol Configuration Options), a Request Type (Request Type), a Header Compression Configuration (Header Compression Configuration).

S502, after receiving the PDN connection Request (PDN Connectivity Request) message, the MME sends a Create Session Request (Create Session Request) message to the SGW.

S503, the SGW sends a Create Session Request (Create Session Request) message to the PGW.

S504, an IP-CAN Session Establishment/Modification Procedure (IP-CAN Session Establishment/Modification Procedure) is performed between the PGW and the PCRF.

S505, the PGW replies to the SGW with a Create Session Response (Create Session Response) message.

After step S505, data may be delivered from the PGW to the SGW.

S506, the SGW replies a Create Session Response (Create Session Response) message to the MME.

S507, the MME sends a Bearer Setup Request (Bearer Setup Request) or a Downlink NAS transport message (Downlink NAS transport) to the base station eNodeB, where the message includes a PDN connection Accept (PDN Connectivity Accept) for nested transport of the NAS message.

S508, the base station eNodeB sends a Radio Resource Control (RRC) Connection Reconfiguration (RRC Connection Reconfiguration) or RRC Direct Transfer (RRC Direct Transfer) message to the UE, and sends a PDN Connection Accept (PDN Connectivity Accept) of the NAS message to the UE.

S509, the terminal UE replies an RRC Connection Reconfiguration Complete (RRC Connection Reconfiguration Complete) message to the base station eNodeB.

S510, the base station eNodeB replies a Bearer Setup Response (Bearer Setup Response) message to the MME.

S511, the UE transmits a NAS message PDN connection Complete (PDN Connectivity Complete) to the base station through a Direct Transfer (Direct Transfer) message.

S512, the base station eNodeB sends a PDN connection Complete (PDN Connectivity Complete) message to the MME.

S513, the MME sends a Modify Bearer Request (Modify Bearer Request) message to the SGW.

S513a, the SGW sends a Modify Bearer Request to the PGW;

s513b, the PGW sends a Modify Bearer Response to the SGW.

S514, the SGW replies an update Bearer Response (Modify Bearer Response) to the MME.

After step S514, the downlink data buffered in the PGW may be sent to the UE.

S515, the MME sends an indication Request (Notify Request) message to the HSS.

S516, the HSS replies an indication Response (Notify Response) message to the MME.

Based on the same inventive concept as the method described above, an embodiment of the present invention further provides a communication apparatus 600, which is applied to the first mobility management network element, for example, the communication apparatus 600 may be a chip or a system-on-chip or one or more processors, which can implement the first mobility management network element. Referring to fig. 6, the communication device 600 includes:

a receiving unit 601, configured to receive context information sent by a second mobility management network element when a terminal device is switched from a first communication network to a second communication network, where the first mobility management network element belongs to the second communication network and the second mobility management network element belongs to the first communication network;

a processing unit 602, configured to determine that a session context of the terminal device is not included in the context information;

a sending unit 603, configured to send a first instruction to the UE when the processing unit 602 determines that the session context of the terminal device is not included in the context information, where the first instruction is used to instruct the terminal device to initiate a public data network PDN connection procedure.

Based on the same inventive concept as the method, the embodiment of the present invention further provides a communication apparatus 700, which is applied to a terminal device, for example, the communication apparatus 700 may be a chip or a chip system capable of implementing the terminal device, or one or more processors. Referring to fig. 7, the communication apparatus 700 includes:

a receiving unit 701, configured to receive a first instruction sent by a first mobility management network element when the terminal device is switched from a first communication network to a second communication network, where the first instruction is used to instruct the terminal device to initiate a public data network PDN connection procedure, and the first mobility management network element belongs to the first communication network;

a processing unit 702, configured to trigger a PDN connection procedure according to the first indication.

Optionally, the communication device further comprises:

a sending unit 703, configured to send a tracking area update request message to the first mobility management network element when the terminal device is switched from a first communication network to a second communication network;

the receiving unit 701 is specifically configured to receive a tracking area update accept message sent by a first mobility management network element, where the tracking area update accept message carries the first indication.

Optionally, the processing unit 702 is specifically configured to trigger a PDN connection procedure according to a first instruction after the tracking area update completion message is sent to the first mobility management network element.

Based on the same inventive concept as the method described above, an embodiment of the present invention further provides a communication apparatus 800, where the communication apparatus 800 is applied to the second mobility management network element, for example, the communication apparatus 800 may be a chip or a chip system capable of implementing the second mobility management network element, or one or more processors. Referring to fig. 8, the communication apparatus 800 includes:

a receiving unit 801, configured to receive, by a second mobility management network element, a context request message sent by a first mobility management network element when a terminal device is switched from a first communication network to a second communication network; the first mobility management network element belongs to a second communication network, and the second mobility management network element belongs to a first communication network;

a processing unit 802, configured to determine that the terminal device does not establish a session in the first communication network;

a sending unit 803, configured to send, when the processing unit 802 determines that the session of the terminal device is not established in the first communication network, a context response message to the MME, where the context response message does not carry the session context of the terminal device.

Optionally, the processing unit 802 is further configured to trigger a procedure of acquiring a session context to a session management network element when it is determined that the terminal device establishes a session in the first communication network.

The division of the unit in the embodiments of the present invention is schematic, and is only a logical function division, and there may be another division manner in actual implementation, and in addition, each functional unit in each embodiment of the present invention may be integrated in one processor, may also exist alone physically, or may also be integrated in one unit by two or more units. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.

Another communication apparatus 900 is provided in the embodiment of the present invention, as shown in fig. 9, including:

a communication interface 901, a memory 902, and a processor 903;

wherein, the communication apparatus 900 communicates with other devices, such as receiving and sending messages, through the communication interface 901; a memory 902 for storing program instructions; and a processor 903 for calling the program instructions stored in the memory 902 and executing the method according to the obtained program.

In the embodiment of the present invention, the specific connection medium among the communication interface 901, the memory 902, and the processor 903 is not limited, for example, a bus, and the bus may be divided into an address bus, a data bus, a control bus, and the like.

In the embodiments of the present invention, the processor may be a general purpose processor, a digital signal processor, an application specific integrated circuit, a field programmable gate array or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component, and may implement or execute the methods, steps, and logic blocks disclosed in the embodiments of the present invention. A general purpose processor may be a microprocessor or any conventional processor or the like. The steps of a method disclosed in connection with the embodiments of the present invention may be directly implemented by a hardware processor, or may be implemented by a combination of hardware and software modules in the processor.

In the embodiment of the present invention, the memory may be a nonvolatile memory, such as a Hard Disk Drive (HDD) or a solid-state drive (SSD), and may also be a volatile memory, for example, a random-access memory (RAM). The memory can also be, but is not limited to, any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. The memory in embodiments of the present invention may also be circuitry or any other device capable of performing a storage function for storing program instructions and/or data.

In a possible implementation manner, the communication apparatus 900 may be applied to a first mobility management element, and the functions of the receiving unit 601, the processing unit 602, and the sending unit 603 may all be implemented by the processor 903. Alternatively, the functions of the receiving unit 601 and the sending unit 603 are implemented by the communication interface 901, the functions of the processing unit 602 are implemented by the processor 903, and specifically, the processor 903 is configured to call the program code in the memory 902, and implement the functions performed by the first mobility management network element in the above-mentioned method through the communication interface 901.

In another possible implementation manner, the communication apparatus 900 may be applied to a terminal device, and the functions of the receiving unit 701, the processing unit 702, and the sending unit 703 may all be implemented by the processor 903. Alternatively, the functions of the receiving unit 701 and the sending unit 703 are implemented by the communication interface 901, the function of the processing unit 702 is implemented by the processor 903, and specifically, the processor 903 is configured to call the program code in the memory 902 and implement the function executed by the terminal device in the above method through the communication interface 901.

In yet another possible implementation manner, the communication apparatus 900 may be applied to a second mobility management network element, and the functions of the receiving unit 801, the processing unit 802, and the sending unit 803 may all be implemented by the processor 903. Alternatively, the functions of the receiving unit 801 and the sending unit 803 are implemented by a communication interface 901, the functions of the processing unit 802 are implemented by a processor 903, and specifically, the processor 903 is configured to call the program code in the memory 902 and implement the functions performed by the second mobility management network element in the above-mentioned method through the communication interface 901.

Embodiments of the present invention also provide a computer-readable storage medium, which includes program code for causing a computer to perform the steps of the method provided above in the embodiments of the present invention when the program code runs on the computer.

Through the scheme provided by the embodiment of the invention, the PDN connection process is triggered by indicating the terminal equipment, so that the 5G network can be switched to the 4G network under the condition that a session is not established in the 5G network, and the process that the terminal equipment is switched between the 4G network and the 5G network is perfected.

As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims

1. A method of communication, comprising:

when the terminal equipment is switched from a first communication network to a second communication network, a first mobility management network element receives context information sent by a second mobility management network element, wherein the first mobility management network element belongs to the second communication network, and the second mobility management network element belongs to the first communication network;

when determining that the context information does not include the session context of the terminal device, the first mobility management network element sends a first indication to the terminal device, where the first indication is used to indicate the terminal device to initiate a Public Data Network (PDN) connection process;

the first mobility management network element is a mobility management entity MME, and the second mobility management network element is an access and mobility management function AMF.

2. A method of communication, comprising:

when the terminal equipment is switched from a first communication network to a second communication network, a second mobility management network element receives a context request message sent by the first mobility management network element; the first mobility management network element belongs to a second communication network, and the second mobility management network element belongs to a first communication network;

and when determining that the session of the terminal device is not established in the first communication network, the second mobility management network element sends a context response message to the first mobility management network element, where the context response message does not carry the session context of the terminal device.

3. The method of claim 2, further comprising:

4. The method according to claim 2 or 3, wherein said first mobility management network element is a mobility management entity, MME, and said second mobility management network element is an access and mobility management function, AMF.

5. A communications apparatus, applied to a first mobility management network element, the communications apparatus comprising:

a sending unit, configured to send a first instruction to the terminal device when the processing unit determines that the context information does not include the session context of the terminal device, where the first instruction is used to instruct the terminal device to initiate a public data network PDN connection procedure;

6. A communications apparatus, applied to a second mobility management network element, comprising:

a sending unit, configured to send a context response message to the first mobility management network element when the processing unit determines that the session of the terminal device is not established in the first communication network, where the context response message does not carry a session context of the terminal device.

7. The communication apparatus according to claim 6, wherein the processing unit is further configured to trigger a procedure of acquiring a session context to a session management network element when it is determined that the terminal device establishes a session in the first communication network.

8. The communication apparatus according to claim 6 or 7, wherein the first mobility management network element is a mobility management entity, MME, and the second mobility management network element is an access and mobility management function, AMF.

9. An apparatus, comprising:

a memory and a processor;

a memory for storing program instructions;

a processor for calling program instructions stored in said memory to execute the method of claim 1 in accordance with the obtained program.

10. An apparatus, comprising:

a memory and a processor;

a memory for storing program instructions;

a processor for calling the program instructions stored in the memory and executing the method of any one of claims 2 to 4 according to the obtained program.

11. A computer readable storage medium having stored thereon computer instructions which, when run on a computer, cause the computer to perform the method of any of claims 1-4.