Patent Description:
In an existing mobile communication network, coverage of a <NUM> or <NUM> network (<NUM>/<NUM> network for short) is wider than coverage of a <NUM> network, and the coverage of the <NUM> network is wider than that of an initial <NUM> network. To ensure service continuity (for example, uninterruptedness of a data service of a user) when a <NUM> user moves out of the coverage of the <NUM> network, a network operator usually overlays the <NUM> network within the coverage of the <NUM> network. Therefore, when user equipment moves, the user equipment generally moves from the <NUM> network area to the <NUM> network area, and then moves to the <NUM>/<NUM> network area. Alternatively, the user equipment performs access in the <NUM>/<NUM> network area, then moves to the <NUM> network area, and then moves to the <NUM> network area.

A conventional technology provides a method used by user equipment to move between a <NUM>/<NUM> network and a <NUM> network to implement service continuity. However, if the user equipment moves to the <NUM> network after accessing the <NUM>/<NUM> network, and then moves from the <NUM> network to a <NUM> network, the UE needs to access the <NUM> network again. As a result, services used by the UE in the <NUM> network are interrupted and service continuity cannot be maintained. Document <CIT> provides a method for maintaining service continuity by a User Equipment (UE) in a wireless communication system. The method includes detecting, by the UE, a change in location during a mobility of the UE from one tracking are to another tracking are within a radio access technology which is referred here as a first radio access technology. Further, on receiving the Registration or Tracking area reject from the core network of first radio access technology, the method includes initiating, by the UE, Initial Registration Request or Initial Attach Request procedure, wherein the UE sends an Registration Request or Attach Request message with other registered radio access technology information referred here as second radio access technology to a core network associated with the first radio access technology.

Embodiments of this application provide a service continuity implementation method, to resolve a prior-art service interruption problem caused by movement of user equipment from a <NUM>/<NUM> network to a <NUM> network and then to a <NUM> network. The present invention is defined by the attached set of claims. Embodiments and aspects which are not covered by the invention should be considered as examples useful for understanding the invention.

Thus, the user identifier may be a globally unique temporary identity, an international mobile subscriber identity, a mobile subscriber ISDN number, or an international mobile equipment identity of the user.

To describe the technical solutions in the embodiments of this application or in the background more clearly, the following describes the accompanying drawings for describing the embodiments of this application or the background.

<FIG> is a schematic diagram of a communication system according to an embodiment of this application.

The communication system provided in this embodiment of this application includes a <NUM>/<NUM> network, a <NUM> network, and a <NUM> network. User equipment (user equipment, UE) may access the <NUM>/<NUM> network via a <NUM>/<NUM> access network device, access the <NUM> network via a <NUM> access network device, or access the <NUM> network via a <NUM> access network device. The access network device may include a base station or the like. The <NUM> network includes a global system for mobile communications (global system for mobile communications, GSM) network and a code division multiple access (code division multiple access) network, and the <NUM> network includes wideband code division multiple access (wideband code division multiple access, WCDMA), a CDMA2000 network, a time division synchronous code division multiple access (Time Division-Synchronous Code Division Multiple Access, TD-SCDMA) network. The <NUM> network includes a long term evolution (long term evolution, LTE) network. The <NUM> network includes a new radio (new radio, NR) network, and the like.

A serving general packet radio service support node (Serving General packet radio service Support Node, SGSN) is mainly used for mobility management of UE in the <NUM> and <NUM> networks. A gateway general packet radio service support node (Gateway General packet radio service Support Node, GGSN) is mainly used for session management and UE data forwarding in the <NUM> and <NUM> networks. The SGSN and the GGSN may be collectively referred to as <NUM>/<NUM> gateways. The SGSN can be deployed independently or together.

A mobility management device may also be referred to as a mobility management entity (mobility management entity, MME), and is mainly responsible for a positioning process, a paging process, and the like of UE in an idle mode in the <NUM> network.

In this embodiment, a <NUM> gateway includes a packet data network gateway (Packet Data Network Gateway, PGW), configured to forward data of the user equipment to the Internet or forward data of the Internet to the UE. In addition, the <NUM> gateway may further include a serving gateway (Serving GateWay, SGW).

In this embodiment, a <NUM> gateway includes a session management function (session management function, SMF) device, which may implement session management on UE accessing the <NUM> network.

In addition, the <NUM> gateway may alternatively be a converged gateway that integrates functions of the GGSN, the SGW, the PGW, and the SMF. If the <NUM> gateway is deployed with a control plane and a user plane separated, the <NUM> gateway in this embodiment may be a device that integrates control plane functions of the SMF and the GGSN, a control plane function of the SGW, and a control plane function of the PGW.

The subscriber database server may store subscription data of a user, and the subscriber data server may integrate functions of a unified data management (unified data management, UDM) device, a home subscriber server (home subscriber server, HSS), and a home location register (home location register, HLR), or may have independent functions of the UDM and the HSS.

In the communication system provided in this embodiment, UE supporting the <NUM> network first accesses the network by using the <NUM>/<NUM> access network, and then the UE moves to the <NUM> network. In this case, the UE initiates a location update procedure. That is, the UE sends a tracking area update (Tracking Area Update, TAU) request message to the MME.

After receiving the TAU request message, the MME determines, based on a <NUM> network capability parameter carried in the TAU request message, that the UE supports <NUM> network access, and further determines whether a user corresponding to the UE is a <NUM> user (that is, whether the user has subscribed to a <NUM> service). If the user is a <NUM> user, the UE is triggered to attach (attach) to the <NUM> network. The UE then initiates a <NUM> network attach procedure. After receiving an attach request sent by the UE, the MME selects, for the UE, a <NUM> gateway supporting a <NUM> capability, and establishes a session with the <NUM> gateway. The <NUM> gateway may send a <NUM>-related parameter (for example, quality of service QoS and a traffic flow template) to the user equipment in advance, so that service continuity is maintained after the UE moves from the <NUM> network to the <NUM> network. That is, services (such as video calls and online videos) on the <NUM> network continue to be maintained on the <NUM> network, improving user experience.

To understand the embodiments of this application in detail, the following provides a detailed method procedure to describe the service continuity implementation method provided in this application.

<FIG> and <FIG> are a flowchart of a service continuity implementation method according to an embodiment of this application.

The method provided in this embodiment mainly includes the following steps.

Step <NUM>. <NUM> user equipment accesses a <NUM>/<NUM> network, and establishes a session with a GGSN.

In this embodiment, the UE first accesses the <NUM>/<NUM> network, for example, when a user is in a location such as an elevator or a garage. After accessing the <NUM>/<NUM> network, the UE establishes a session with a <NUM>/<NUM> gateway. The UE can use services provided by the <NUM>/<NUM> network.

In this embodiment, the <NUM>/<NUM> gateway includes an SGSN and the GGSN. The GGSN and a <NUM> gateway are deployed together, and the SGSN is deployed independently of the GGSN.

If the UE moves to an area covered by a <NUM> network, the UE accesses a <NUM> access network. The <NUM> access network is a long term evolution (long term evolution, LTE) network.

Step <NUM>. The UE sends a location update request message to an MME.

After accessing the LTE network, the UE sends a TAU request message (TAU request for short) to the MME. The TAU request message carries a user identifier and a <NUM> capability of the UE. In addition, the TAU request message may further carry a tracking area identifier of the UE.

The <NUM> capability of the UE may be carried by using a UE Network Capability parameter in the TAU request. For example, if a value of this parameter is N1 mode support, it indicates that the UE has a <NUM> capability, that is, the UE supports <NUM> network access.

In addition, the TAU request may further carry a UE status information element, and the MME determines that the UE moves from the <NUM>/<NUM> network to the <NUM> network based on the information element. Specifically, if the TAU request does not carry the UE status information element, the MME may determine that the UE moves from the <NUM>/<NUM> network to the <NUM> network.

After determining that the UE moves from the <NUM>/<NUM> network to the <NUM> network, the MME performs a procedure of switching a bearer of the UE from the <NUM>/<NUM> network to the <NUM> network, which specifically includes steps 202a, 202b, and <NUM>.

Steps 202a and 202b. The MME requests a user context from the SGSN.

Step <NUM>. The MME requests the <NUM> gateway to switch the bearer of the user from the GGSN to the <NUM> gateway.

In this embodiment, the <NUM> gateway includes an SGW and a PGW. The <NUM> gateway and the GGSN are deployed together.

Step <NUM>. The MME initiates location update to a user database server.

After switching the bearer of the UE from the GGSN to the <NUM> gateway, the MME initiates the location update to the user database server.

The MME may send a location update request message to the user database server, where the location update request message carries the user identifier. The user identifier may be a globally unique temporary identity, an international mobile subscriber identity, a mobile subscriber ISDN number, or an international mobile equipment identity.

The user database server records a location of the UE, obtains subscription data of the user based on the user identifier, and then sends a location update response message to the MME, where the response message carries the subscription data of the user. For example, the subscription data carries <NUM> subscription information indicating whether entering a <NUM> core network is allowed (Core Network Restriction parameter) and a capability of whether switching a bearer to <NUM> is allowed (Interworking 5GS Indicator parameter).

Step <NUM>. The MME determines that the user corresponding to the UE is a <NUM> user.

In this embodiment, the subscription data carries information indicating that the user has subscribed to a <NUM> service. Therefore, the MME may determine that the user corresponding to the UE is a <NUM> user. If the subscription data does not carry the information related to the <NUM> service, that is, the UE has not subscribed to the <NUM> service, the MME determines that the user is a non-<NUM> user, and performs a normal TAU procedure.

Step <NUM>. The MME returns a TAU reject message to the UE, to reject tracking area update of the UE.

In this embodiment, the MME triggers, by sending the TAU reject (reject) message to the UE, the UE to attach to the <NUM> network, where the message may carry a cause value, for example, implicitly detached.

After receiving the TAU reject message, the UE re-initiates a request of attaching to the <NUM> network.

Step <NUM>. The MME sends request information for deleting a session of the UE to the <NUM> gateway.

In this embodiment, the MME sends a session deletion request to the <NUM> gateway, requesting to delete the session of the UE on the <NUM> gateway. The PGW and the SGW delete their local UE sessions (or deactivate the bearer of the UE). Step <NUM>. The MME receives an attach request sent by the UE.

The attach request may carry the <NUM> capability of the UE.

In this embodiment, if the MME that receives the attach request is different from the MME that previously sends the TAU reject message, the MME that receives the attach request may further perform step <NUM>, to obtain the subscription data of the user.

If the MME that receives the attach request is the same as the MME that previously sends the TAU reject message, step <NUM> is not performed, and step <NUM> is performed.

Step <NUM>. The MME sends location update to the user database server.

For a specific location update process, refer to step <NUM>. After obtaining the subscription data of the user, the MME may further determine whether the user corresponding to the UE is a <NUM> user. If yes, step <NUM> is performed.

If the user corresponding to the UE is not a <NUM> user, an attach procedure in a conventional technology is performed, to select a <NUM> gateway for the UE.

Step <NUM>. The MME selects a <NUM> gateway for the user equipment.

Step <NUM>. The MME establishes a session with the <NUM> gateway.

The step of establishing the session by the MME specifically includes: The MME sends a create session request to the <NUM> gateway, and the <NUM> gateway returns a create session response to the MME, where the response may carry a <NUM>-related parameter, such as quality of service QoS and a traffic flow template (traffic flow template, TFT).

Step <NUM>. After establishing the session with the <NUM> gateway, the MME returns an attach accept message to the UE, so that the UE completes a subsequent <NUM> network attach procedure.

In this embodiment, after the MME selects the <NUM> gateway for the UE, an address of the UE may remain unchanged after the UE subsequently moves to the <NUM> network, so that a service is kept uninterrupted.

<FIG> and <FIG> are a flowchart of another service continuity implementation method according to an embodiment of this application.

The service continuity implementation method provided in this embodiment mainly includes the following steps. Step <NUM>. <NUM> user equipment accesses a <NUM>/<NUM> network, and establishes a session with a GGSN.

Steps 302a and 302b. The MME requests a user context from an SGSN.

Step <NUM>. The MME requests a <NUM> gateway to switch a bearer of a user from the GGSN to the <NUM> gateway.

An execution process of steps <NUM> to <NUM> is the same as that of steps <NUM> to <NUM> in the foregoing embodiment. For details, refer to the foregoing embodiment. Details are not repeated herein.

After completing the location update, the MME returns a TAU accept message to the UE.

Step <NUM>. The MME sends the TAU accept message to the UE.

In this embodiment, the subscription data carries information indicating that the user has subscribed to a <NUM> service. Therefore, the MME may determine that the user corresponding to the UE is a <NUM> user. If the subscription data does not carry the information related to the <NUM> service, that is, the UE has not subscribed to the <NUM> service, the MME determines that the user is a non-<NUM> user.

In this embodiment, the MME triggers, by detaching the UE, the UE to attach to the <NUM> network.

Specifically, the MME may send a detach (detach) request to the UE, where the detach request carries a specified attach type, for example, re-attach required. In addition, the MME further sends a detach request to the <NUM> gateway, so that the <NUM> gateway may delete a session created for the user equipment, to save system resources.

After receiving the detach request, the UE re-initiates a request of attaching to the <NUM> network.

Step <NUM>. The MME receives an attach request sent by the UE.

<FIG> is a schematic diagram of a mobility management device according to an embodiment of this application. The mobility management device provided in this embodiment uses general-purpose computer hardware, including a processor <NUM>, a memory <NUM>, a bus <NUM>, an input device <NUM>, and an output device <NUM>.

Specifically, the memory <NUM> may include computer storage media in a form of a volatile and/or nonvolatile memory, such as a read-only memory and/or a random access memory. The memory <NUM> may store an operating system, an application program, another program module, executable code, program data, user registration data, user subscription data, and the like.

The input device <NUM> may be configured to enter a command and information to the mobility management device. The input device <NUM> may be a keyboard or a pointing device, such as a cursor mouse, a trackball, a touchpad, a microphone, a joystick, a play mat, a satellite dish, a scanner, or a similar device. The input devices may be connected to the processor <NUM> by using the bus <NUM>.

The output device <NUM> may be used by the mobility management device to output information. The output device <NUM> may be a monitor, or may be other peripheral output devices, such as a loudspeaker and/or a printing device, and the output devices may be connected to the processor <NUM> by using the bus <NUM>.

The mobility management device may be connected to a network through a network interface <NUM>, for example, connected to a local area network (Local Area Network, LAN). In a network connection environment, computer-executable instructions stored in the mobility management device may be stored in a remote storage device, and are not limited to being locally stored.

When the processor <NUM> in the mobility management device executes the executable code or the application program stored in the memory <NUM>, the mobility management device may perform the method steps on the mobility management device side in the foregoing embodiments, for example, perform steps <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. For a specific execution process, refer to the foregoing embodiments.

<FIG> is a schematic diagram of a mobility management device according to an embodiment of this application.

As shown in the figure, the mobility management device may include a first receiving module <NUM>, a determining module <NUM>, an attach triggering module <NUM>, a selection module <NUM>, and a session establishment module <NUM>.

The first receiving module <NUM> may be configured to receive a tracking area update request message for a <NUM> network sent by user equipment, where the request message carries a user identifier and a <NUM> capability of the user equipment. The determining module <NUM> is configured to determine, based on the user identifier, that a user is a <NUM> user.

The attach triggering module <NUM> is configured to trigger the user equipment to attach to the <NUM> network. The first receiving module <NUM> is further configured to receive an attach request sent by the user equipment.

The selection module <NUM> is configured to select a <NUM> gateway for the user equipment.

The session establishment module <NUM> is configured to establish a session with the <NUM> gateway.

The mobility management device provided in this embodiment can implement service continuity of the user equipment through cooperation among the first receiving module <NUM>, the determining module <NUM>, the attach triggering module <NUM>, the selection module <NUM>, and the session establishment module <NUM> in the foregoing service continuity implementation method in the foregoing embodiments. This resolves a prior-art problem of service interruption caused by movement of the user equipment from the <NUM>/<NUM> network to the <NUM> network and then from the <NUM> network to the <NUM> network.

In the mobility management device provided in this application, that the attach triggering module <NUM> triggers the user equipment to attach to the <NUM> network may specifically include: The attach triggering module <NUM> sends a tracking area update reject message to the user equipment, to reject tracking area update of the user equipment.

In addition, the attach triggering module <NUM> may also detach the user equipment, for example, send a detach request to the user equipment.

In the mobility management device provided in this application, the determining module <NUM> may specifically include:.

The mobility management device provided in this application may further include a session deletion module, configured to: after the attach triggering module <NUM> sends the tracking area update reject message to the user equipment, send a request message for deleting a session of the user equipment to a <NUM> gateway. In this way, the gateway may delete the session of the user equipment stored in the gateway.

The mobility management device in the foregoing embodiment is presented in a form of functional modules. The "module" herein may be an application-specific integrated circuit, a processor and a memory that execute one or more software or firmware programs, an integrated logic circuit, and/or another component that can provide the foregoing functions.

In the mobility management device provided in the foregoing embodiment, functions implemented by function modules such as the determining module <NUM> and the selection module <NUM> in the mobility management device may all be implemented by using the processor <NUM> and the memory <NUM> in <FIG>. For example, a function of determining, by the determining module <NUM> based on the user identifier, that the user is a <NUM> user may be implemented by the processor <NUM> by executing the code stored in the memory <NUM>. A function of selecting the <NUM> gateway for the user equipment by the selection module <NUM> may also be implemented by the processor <NUM> by executing the code stored in the memory <NUM>.

Claim 1:
A service continuity implementation method, comprising:
receiving (S202, S302), by a mobility management device, a tracking area update request message for a <NUM> network from a user equipment, wherein the tracking area update request message comprises a user identifier and a <NUM> capability of the user equipment, wherein a user corresponding to the user identifier is a <NUM> user;
triggering (S206, S307), by the mobility management device, the user equipment to attach to the <NUM> network;
afterwards, receiving (S208, S308), by the mobility management device, an attach request from the user equipment, and the attach request is issued for the <NUM> network;
after receiving the attach request, sending (S211, S311), by the mobility management device, a create session request, for establishing a session with a <NUM> gateway, to the <NUM> gateway, wherein the <NUM> gateway is selected for the user equipment;
receiving (S211a, S311a), by the <NUM> gateway, the create session request;
returning (S211b, S311b), by the <NUM> gateway, a create session response to the mobility management device, wherein the create session response comprises a <NUM>-related parameter; and
returning (S212), by the mobility management device, after establishing the session with the <NUM> gateway, an attach accept message to the user equipment,
wherein after the mobility management device selects the <NUM> gateway for the user equipment, an address of the user equipment remains unchanged after the user equipment subsequently moves to the <NUM> network, so that a service is kept uninterrupted.