CN101568163A

CN101568163A - Network selection method, mobile terminal, and IP address processing method and system

Info

Publication number: CN101568163A
Application number: CNA2008101051113A
Authority: CN
Inventors: 吴问付; 沈斌; 胡伟华; 周汉
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2008-04-25
Filing date: 2008-04-25
Publication date: 2009-10-28
Also published as: WO2009129748A1

Abstract

Embodiments of the present invention relate to a network selection method, a mobile terminal, an IP address processing method, and a system. The selection method selects a target network according to IP address information used by a UE in a source network and available access network information. The selection system includes UE and ANDSF network elements; the terminal includes an available access network information acquisition unit and a selection unit, which ensures that the IP address used by the UE in the target network is consistent with the IP address used in the source network. The IP address processing method specifies the IP address information used by the UE in the target network according to the IP address information used by the UE in the source network, and sends the IP address information to the user plane anchor gateway. The processing system includes an IP address acquisition unit, a target IP designation unit, and a designation notification unit. It is guaranteed that the target network continues to use the IP address information used by the UE in the source network.

Description

Network selection method, mobile terminal, IP address processing method and system

Technical Field

The present invention relates to network technologies, and in particular, to a network selection method, a mobile terminal, and an IP address processing method and system.

Background

At present, a network handover process when a User Equipment (UE) is handed over from a non-3GPP network to a 3GPP network specifically includes:

the UE accesses in the non-3GPP network. For a Wireless Local Area Network (WLAN) system, the Non-3GPP Access network element in this step is an Evolved Packet Data Gateway (EPDG); for a Worldwide Interoperability for Microwave Access (WiMAX) system, the Non-3gpp Access Network element in this step is an Access Service Network Gateway (ASN GW); for a Code Division Multiple Access (CDMA) system, the Non-3GPP Access network element in this step is an Access Gateway (AGW); for a High Rate Packet Data (HRPD) network, the Non-3GPP Access network element in this step is a Packet Data Serving Node (PDSN).

The UE initiates a handover between the non-3GPP network to the 3GPP network. Sending an Attach Request (Attach Request) message to a mobility management network element through an access network element of a 3GPP network; or the UE needs to be switched to the 3GPP network, but the UE also resides in the non-3GPP network, and the UE sends an attachment request message to a mobility management network element through an access network element of the non-3GPP network. For a GSM/EDGE Radio Access Network (GERAN)/UMTS Terrestrial Radio Access Network (UTRAN) Network, a mobility management Network element is a Serving GPRS Support Node (SGSN); for an Evolved UMTS Terrestrial radio access Network (E-UTRAN) Network, the mobility management element is mme (mobility management entity).

After an authentication procedure is performed among the UE, the mobility management element, and the Home Subscriber Server (HSS), a Location Update and subscription Data insertion (Update Location and Insert Subscriber Data) procedure is performed between the mobility management element and the HSS.

The mobility management network element initiates a PDN connection establishment procedure for each obtained Access Point Name (APN) and PGW address record, that is, sends a create default Bearer Request (CreateDefault Bearer Request) message. Sending the information to a PGW through a Serving Gateway (Serving Gateway); and the PGW locates the PDN connection used by the UE according to the message, and keeps the IP address corresponding to the PDN connection unchanged, namely the PGW continues to use the corresponding IP address allocated by the UE in the non-3GPP network for the PDN connection without allocating the IP address for the PDN connection, thereby completing the network switching.

In the process of implementing the invention, the inventor finds that the prior art has at least the following defects: in the above process, what type of address the UE uses in the target network is determined by the target network, so that the IP address used by the mobile terminal in the source network cannot be used in the target network when the mobile terminal in the source network has different IP address capabilities from the target network is handed over to the network.

Disclosure of Invention

The embodiment of the invention provides a network selection method, a system and a mobile terminal, which are used for realizing that UE preferentially selects a target network with the same IP address capability as a source network, so that an IP address used by the UE in the source network can be continuously used in the target network.

The embodiment of the invention also provides an IP address processing method and system during network switching, so as to realize that the UE can continuously use the IP address distributed by the UE in the source network in the target network.

The embodiment of the invention provides a network selection method, which comprises the following steps:

acquiring IP address information and/or available access network information;

and selecting a target network from the available access networks according to the IP address information used by the user equipment in the source network and the available access network information.

By selecting the target network before network switching, the user equipment UE preferentially selects the target network with the same IP address capability as the source network, so that the IP address used by the UE in the source network can be continuously used in the target network.

The embodiment of the invention also provides an IP address processing method during network switching, which comprises the following steps:

acquiring IP address information used by user equipment in a source network;

according to the IP address information used by the user equipment in a source network, the IP address information used by the user equipment in a target network is appointed;

and sending the appointed IP address information to a user plane anchor point gateway.

An embodiment of the present invention further provides a mobile terminal, including:

an available access network information obtaining unit, configured to obtain the available access network information from a network side;

and the selection unit is used for selecting the target network from the available access networks according to the IP address information used by the user equipment in the source network and the available access network information.

The embodiment of the invention also provides a network selection system, which comprises user equipment and an access network discovery and selection function ANDSF network element, wherein the ANDSF network element is used for providing available access network information;

the user equipment is used for acquiring available access network information from the ANDSF network element and selecting a target network from available access networks according to the IP address information used by the user equipment in a source network and the available access network information; or

The user equipment is used for reporting information;

and the ANDSF network element is used for acquiring the IP address information of the user equipment in a source network according to the reported information of the user equipment, and selecting a target network from the available access networks according to the IP address information used by the user equipment in the source network and the available access network information.

An embodiment of the present invention further provides an IP address processing system, including:

an IP address obtaining unit, configured to obtain IP address information used by a user equipment in a source network;

a target IP appointing unit, which is used for appointing the IP address information used by the user equipment in the target network according to the IP address information used by the user equipment in the source network;

and the appointed notification unit is used for sending the appointed IP address information to the user plane anchor point gateway.

In the above IP address processing embodiment, the network handover process realizes that the UE can continue to use the IP address allocated by the UE in the source network in the target network by specifying the IP address information.

The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.

Drawings

FIG. 1 is a schematic diagram of a network system according to an embodiment of the present invention;

FIG. 2 is a flow chart of an embodiment of the inventive network selection method;

FIG. 3 is a corresponding signaling flow diagram of FIG. 2;

FIG. 4 is a flowchart of an embodiment of a method for processing an IP address during network handover;

FIG. 5 is a flowchart illustrating an embodiment of an IP address processing method applied to a non-3GPP network requiring to be switched to a 3GPP network when the network is switched;

FIG. 6 is a flowchart of an embodiment of an IP address processing method for switching a 3GPP network to a non-3GPP network in network switching according to the present invention;

FIG. 7 is a flowchart of an IP address processing method for UE22 to be handed over from a 3GPP network to a non-3GPP network according to another embodiment of the present invention;

FIG. 8 is a schematic structural diagram of a network selection system according to an embodiment of the present invention;

FIG. 9 is a schematic structural diagram of a mobile terminal according to an embodiment of the present invention;

fig. 10 is a schematic structural diagram of an IP address processing system according to an embodiment of the present invention.

Detailed Description

Fig. 1 is a schematic diagram of a Network system structure, that is, a system architecture diagram of an Evolved Network, applied in the embodiment of the present invention, including an Evolved UMTS Terrestrial Radio Access Network (E-UTRAN) 11, a Mobility management Network element (MME) 12, a Serving Gateway (SGW) 13, a Packet Data Network Gateway (PGW) 14, a Policy and Charging Rule Function (Policy and Charging Rule Function, PCRF)15, a Home Subscriber Server (HSS) 16, a UMTS Terrestrial Radio Access Network (UTRAN) 17, a GSM/EDGE Radio Access Network (GSM/EDGE Radio Network, universal GPRS Network, GPRS Access Network (GPRS) 19), a Serving GPRS Access Network (GPRS Access Node, GPRS Access Network Node, and GPRS Access Node (GPRS Access Node, GPRS Access Network Node, GPRS Access Network, GPRS Access Node, and GPRS Access Node Access Network, GPRS Access Node, and GPRS Access Node, Authorization and Accounting Server (AAA Server) 21:

the E-UTRAN11 is used for realizing all functions related to the wireless of the evolution network; the MME 12 is responsible for mobility management of a control plane, including user context and mobility state management, allocating user temporary identity, and the like; SGW13 is the user plane anchor point between 3GPP access networks, terminating the interface of E-TURAN 11; the PGW14 is a user plane anchor between a 3GPP access Network and a non-3GPP access Network, and terminates interfaces with external Packet Data Networks (PDNs) (referred to as user plane anchor gateways in this patent). PCRF 15 is used for policy control decision and flow charging control functions. The HSS16 is used to store subscriber subscription information.

The UTRAN17 and GERAN 18 are used to implement all radio related functions in existing GPRS/UMTS networks. The SGSN 19 is used for implementing functions of route forwarding, mobility management, session management, and user information storage in the GPRS/UMTS network. The Non-3GPP IP Access 20 is mainly an Access Network defined by some Non-3GPP organizations, such as a Wireless Local Area Network (WLAN), a Worldwide Interoperability for Microwave Access (Wimax), a Code Division Multiple Access (CDMA), and so on. The AAA Server 21 is used to perform access authentication, authorization and accounting functions for a User Equipment (UE) 22.

Fig. 2 is a flowchart of an embodiment of a network selection method of the present invention, and fig. 3 is a corresponding signaling flowchart, which is mainly used for explaining a process of acquiring available access network information, and specifically includes:

step 201, acquiring an IP protocol stack supported by an available access network, or an IP protocol stack capability type supported by an available access network PDN connection, or an IP protocol stack supported by an access network and an I P protocol stack capability type supported by an available access network PDN connection;

the UE sends an Access Network information Request (Access Network Info Request) message to an Access Network Discovery and Selection Function (ANDSF) Network element to obtain information of an Access Network at a current location of the UE. The functional entity of the ANDSF network element includes inter-system mobility policy rules specified by an operator, information of an available access network in a current location of the UE, and the like.

The ANDSF Network element returns an Access Network information Response (Access Network Info Response) message to the UE22, where the message carries available Access Network information of the current location of the UE22 and inter-system mobility policy rules specified by an operator. The available access network information includes: an access network type (e.g., an E-UTRAN11 network, a Wimax network, a CDMA network, etc.), an IP protocol stack capability type supported by a PDN connection of the access network (an IP dual stack (i.e., an IPv4 address and an IPv6 address can be used in one PDN connection), an IP single stack (i.e., only an IPv4 address or an IPv6 address can be used in one PDN connection)), or an IP protocol stack supported by the access network (IPv4 or IPv6 or IPv4/IPv6), or an IP protocol stack capability type supported by a PDN connection of the access network and an IP protocol stack supported by the access network.

Step 203, selecting a target network according to IP address information used by PDN connection in a source network and IP protocol stack capability types supported by the PDN connection of an available access network; or, selecting a target network according to IP address information used by PDN connection in a source network and an IP protocol stack supported by an available access network; or, selecting a target network according to the IP address information used by the PDN connection in the source network, the IP protocol stack capability type supported by the PDN connection of the available access network and the IP protocol stack supported by the access network;

the UE22 makes access network selection and handover decisions (UE map access network selection and handover decision).

The method specifically comprises the following steps:

the UE22 selects the target network based on the IP address information used by the PDN connection of the current network (i.e., the source network) of the UE22 and the IP protocol stack capability types supported by the PDN connections of the available access networks. For example:

a) the UE22 uses dual IP addresses for a single PDN connection in the source network, and if there is an access network whose IP protocol stack capability type supported by the PDN connection of the access network is IP dual stack in the available access network information, the UE22 prefers this access network as the target access network. Or,

b) the UE22 uses a single IP address for a single PDN connection in the source network, and if there is an access network whose IP protocol stack capability type supported by the access network PDN connection is IP dual stack in the available access network information, the UE22 prefers this access network as the target access network.

Or specifically may be:

the UE22 selects the target network based on the IP address information used by the PDN connection of the UE22 in the source network and the IP protocol stack supported by the available access networks. For example:

a) the UE22 uses dual IP addresses for a single PDN connection in the source network, and there is an access network with IPv4/IPv6 dual stack IP protocol stack supported by the access network in the available access network information, so the UE22 prefers this access network as the target access network. Or,

b) the UE22 uses dual IP addresses for a single PDN connection in the source network, and if an access network with an IP protocol stack supported by the access network being IPv4/IPv6 dual stack does not exist in the available access network information, but an access network with an IP protocol stack supported by the access network being IPv6 exists, the UE22 prefers this access network to be the target access network. Or,

c) the UE22 uses a single IP address for a single PDN connection in the source network, and if there is an access network whose IP protocol stack supported by the access network is IPv4/IPv6 dual stack in the available access network information, the UE22 prefers this access network as the target access network. Or,

d) the single PDN connection of the UE22 in the source network uses a single IP address, and an access network whose IP protocol stack supported by the access network is not present in the available access network information is an IPv4/IPv6 dual stack is available, so that the UE22 prefers an access network whose IP protocol stack supported by the access network is consistent with the IP protocol stack currently used by the UE22 as the target access network.

Or specifically may be:

the UE22 selects the target network according to the IP address information used by the PDN connection of the UE22 in the source network, and the IP protocol stack capability types supported by the available access network PDN connections and the IP protocol stacks supported by the access network. For example:

b) the UE22 uses double IP addresses in a single PDN connection in a source network, and if an access network with IP protocol stack capability type supported by the PDN connection of the access network as IP double stack does not exist in the available access network information, but an access network with IP protocol stack supported by the access network as IPv4/IPv6 exists, the UE

This access network is preferably the target access network 22. Or,

c) the UE22 uses dual IP addresses for a single PDN connection in the source network, and if there is no access network in the available access network information where the IP protocol stack capability type supported by the PDN connection of the access network is IP dual stack and there is no access network in which the IP protocol stack supported by the access network is IPv4/IPv6 but there is an access network in which the IP protocol stack supported by the access network is IPv6, the UE22 prefers this access network to be the target access network. Or,

d) the UE22 uses a single IP address for a single PDN connection in the source network, and if there is an access network whose IP protocol stack capability type supported by the access network PDN connection is IP dual stack in the available access network information, the UE22 prefers this access network as the target access network. Or,

e) the UE22 uses a single IP address for a single PDN connection in the source network, and if there is no access network in the available access network information that has an IP stack capability type supported by the access network PDN connection and is an IP dual stack, but there is an access network that has an IP stack supported by the access network and is an IPv4/IPv6 dual stack, then the UE22 prefers this access network to be the target access network. Or,

f) the UE22 uses a single IP address for a single PDN connection in the source network, and if there is no access network in the available access network information where the IP protocol stack capability type supported by the PDN connection of the access network is IP dual stack and there is no access network where the IP protocol stack supported by the access network is IPv4/IPv6 but there is an access network where the IP protocol stack supported by the access network is consistent with the IP protocol stack currently used by the UE22, the UE22 prefers this access network to be the target access network.

It should be noted that: the above selection process is performed by the ANDSF network element if the decision of the target access network to which the UE22 is to be handed over is made by the ANDSF network element. At this time, in step 201, the UE22 reports the IP protocol stack (IPv4 or IPv6 or IPv4/IPv6) currently used by the UE22 to the ANDSF network element. And after the decision of the ANDSF network element is executed, the UE22 is informed of the decided target access network information.

In this embodiment, the mobile terminal obtains the available access network information from the ANDSF network element, and selects the target network to be switched according to the IP address information used by the mobile terminal in the source network and the available access network information, or the ANDSF network element obtains the IP address information used by the mobile terminal in the source network from the information reported by the mobile terminal, and selects the target network to be switched according to the obtained IP address information and the available access network information, so that the following scenarios are implemented:

1. the UE uses the IPv6 address in the source network, and the target network sets the IP address request indication information to be IPv4, namely the target network requires the UE to use the IPv4 address;

2. the UE uses an IPv4 address in the source network, while the target network requires the UE to use IPv 6;

3. the UE uses an IPv4 address and an IPv6 address in the source network, while the target network only requires the UE to use either an IPv4 address or an IPv6 address;

the method and the device avoid the situation that the target network can not continuously use the IP address used by the UE in the source network, and also avoid the problem that the service used by the mobile terminal in the source network is interrupted or part of the service is interrupted due to the loss of the IP address used by the mobile terminal, so that the mobile terminal is switched to the target network with the same IP address capability as the source network in a plurality of available access networks with different capabilities in a preferred mode, the IP address used by the mobile terminal in the source network can be continuously used in the target network, and the user experience of the mobile terminal is greatly improved.

Fig. 4 is a flowchart of an embodiment of an IP address processing method for network handover, which specifically includes:

step 301, acquiring the IP address information used by the user equipment in the source network;

step 302, the IP address information used by the user equipment in the target network is appointed according to the IP address information used by the user equipment in the source network.

Step 303, sending the specified IP address information to a user plane anchor point gateway PGW, which may specifically be:

sending a PDN connection establishment request (a requested message may be a PDN connection request message, a default bearer creation request message, an agent binding update message, or a binding update message, and a specific message name is not limited in this patent) to the PGW, where the request carries IP address request indication information, and the IP address request indication information carries the determined IP address information;

the PDN connection establishment request may be initiated by the UE22, or may be initiated by a network side network element, such as a mobility management network element.

When UE initiates a PDN connection establishment request and establishes a PDN connection established by the UE in a source network in a target network, the UE requests a corresponding IP address according to IP address information used by the PDN connection of the UE in the source network. For example:

1. the UE uses dual stacks for PDN connections in the source network, then the UE requests IPv4 and IPv6 addresses in a UE-initiated PDN connection Request (PDNConnection Request) message. Accordingly, the PGW continues to use the IPv4 and IPv6 addresses allocated by the UE in the source network after receiving the request. Or,

2. and the PDN connection of the UE in the source network uses a single stack, and the UE requests an IPv4 or IPv6 address in the PDN ConnectionRequest initiated by the UE, wherein the requested IP address type is the same as the IP address type used by the PDN connection of the UE in the source network. Accordingly, the PGW continues to use the IPv4 or IPv6 address allocated by the UE in the source network after receiving the request.

When the UE22 initiates a PDN connection establishment request and establishes a PDN connection established by the UE22 in the source network in the target network, the UE22 requests a corresponding IP address according to IP address information used by the PDN connection of the UE22 in the source network and an IP protocol stack capability type supported by the PDN connection of the target network. For example:

1. the UE22 uses dual stacks for PDN Connection in the source network, and the IP protocol stack capability type supported by the PDN Connection in the target network is IP dual stack, so that the UE22 requests IPv4 and IPv6 addresses in the PDN Connection Request initiated by the UE 22. Accordingly, PGW14, upon receiving this request, continues to use the IPv4 and IPv6 addresses assigned by UE22 in the source network. Or,

2. the UE22 uses dual stacks for PDN connections in the source network, and the IP protocol stack capability type supported by the PDN Connection of the target network is IP single stack, so the UE22 initiates a PDN Connection Request in the target network twice for each PDN Connection in the source network, where the UE22 requests an IPv4 address in one PDN Connection Request message, and the UE22 requests an IPv6 address in another PDN Connection Request message. Accordingly, the PGW splits the original PDN connection into two PDN connections. Dividing the corresponding service data flow into corresponding PDN connection according to the corresponding IP address; the UE22 also divides the respective traffic data flows into the respective PDN connections according to the respective IP addresses. Or,

3. if the UE uses a single stack in the PDN connection of the source network, the UE22 requests an IPv4 or IPv6 address in the PDN ConnectionRequest initiated by the UE22, and the requested IP address type is consistent with the IP address type used by the UE in the source network.

When the UE22 initiates a PDN connection establishment request and establishes a PDN connection established by the UE22 in the source network in the target network, the UE22 requests a corresponding IP address according to IP address information used by the PDN connection of the UE22 in the source network, an IP protocol stack capability type supported by the PDN connection of the target network, and I P protocol stack information supported by the target network. For example:

1. the UE22 uses dual stacks for PDN connections in the source network, the IP protocol stack capability type supported by the target network PDN Connection is IP dual stack and the IP protocol stack supported by the target network is IPv4/IPv6, then the UE22 requests IPv4 and IPv6 addresses in the PDN Connection Request initiated by the UE 22. Accordingly, PGW14, upon receiving this request, continues to use the IPv4 and IPv6 addresses assigned by UE22 in the source network. Or,

2. the UE uses double stacks in the PDN Connection of the source network, the IP protocol stack capability type supported by the PDN Connection of the target network is IP single stack but the IP protocol stack supported by the target network is IPv4/IPv6, then the UE22 initiates PDN Connection Request in the target network twice for each PDN Connection in the source network, the UE22 requests an IPv4 address in one PDN Connection Request message, and the UE22 requests an IPv6 address in the other PDN Connection Request message. Accordingly, the PGW splits the original PDN connection into two PDN connections. Dividing the corresponding service data flow into corresponding PDN connection according to the corresponding IP address; the UE22 also divides the respective traffic data flows into the respective PDN connections according to the respective IP addresses. Or,

3. the UE22 uses dual stacks for PDN connections in the source network, the IP protocol stack capability type supported by the target network PDN connection is IP single stack (or IP dual stack) and the target network only supports IPv4 or IPv6, then the UE22 initiates a PDN ConnectionRequest for each PDN connection in the source network, the UE22 requests an IPv4 or IPv6 address in the message and indicates that the target network only uses single stack, and at the same time the UE22 releases the other IP address and deletes the relevant information used by this IP address (e.g. TFT (transport Flow Template) used by this address). Accordingly, after receiving the request, the PGW continues to use the IPv4 or IPv6 address allocated by the UE22 in the source network, releases the other IP address, and releases the information used by the IP address, such as a transport stream template (TFT, Traffic Flow template or,

4. the UE22 uses a single stack for the PDN connection in the source network, and then the UE22 requests either an IPv4 or IPv6 address in the PDNConnection Request initiated by the UE22, the requested IP address being of the same type as the IP address used by the UE22 for the PDN connection in the source network. Accordingly, upon receipt of this request, the PGW14 proceeds to use the IPv4 or IPv6 address assigned by the UE22 in the source network.

When a network side network element initiates a PDN connection establishment request and establishes a PDN connection established by UE22 in a source network in a target network, the network side network element determines IP address request indication information according to IP address information used by the UE in the PDN connection of the source network. For example,

1. and the UE uses double stacks in the PDN connection of the source network, and double IP addresses (IPv4 and IPv6 addresses) are requested in a PDN connection establishment procedure initiated by a network element at the network side. Accordingly, the PGW continues to use the IPv4 and IPv6 addresses allocated by the UE in the source network after receiving the request. Or,

2. if the UE uses a single stack for the PDN connection of the source network, the network element of the network side requests an IPv4 or IPv6 address (the requested IP address type is the same as the IP address type used for the PDN connection of the UE22 in the source network) or the network element of the network side requests a single IP address in the PDN connection establishment procedure initiated by the network element of the network side. Accordingly, PGW14, upon receiving this request, continues to use the IPv4 or IPv6 address assigned by UE22 in the source network.

When a network side network element initiates a PDN connection establishment request and establishes a PDN connection established by UE22 in a source network in a target network, the network side network element sets IP address request indication information in the PDN connection request according to IP address information used by the PDN connection of the UE22 in the source network and the IP protocol stack capability type supported by the PDN connection of the target network, and requests a corresponding IP address. For example:

1. the UE uses double stacks in PDN connection in a source network, and the IP protocol stack capability type supported by the PDN connection of a target network is IP double stacks, so that double IP addresses (IPv4 and IPv6 addresses) are requested in a PDN connection establishment program initiated by a network element at a network side. Accordingly, the PGW continues to use the IPv4 and IPv6 addresses allocated by the UE in the source network after receiving the request. Or,

2. the PDN connection in the source network of the UE uses double stacks, the IP protocol stack capability type supported by the PDN connection of the target network is IP single stack, then the network side network element initiates a PDN connection establishment program once for each PDN connection in the source network in the target network, and the network side network element requests an IPv4 or IPv6 address or the network side network element requests a single IP address in the establishment program. Accordingly, PGW14, upon receiving this request, continues to use the IPv4 or IPv6 address assigned by UE22 in the source network. The UE22 finds in the received acceptance message that this PDN connection only uses one IP address and there are two IP addresses in the original PDN connection, then the UE22 initiates another PDN connection establishment procedure, instructing the network side to allocate another IP address. Or,

3. and the network element at the network side initiates a PDN connection establishment program twice in the target network for each PDN connection in the source network, wherein the network element at the network side requests an IPv4 address in the PDN connection establishment program once, and the network element at the network side requests an IPv6 address in the PDN connection establishment program once. The PGW splits the original PDN connection into two PDN connections. The corresponding traffic data flows are divided into the corresponding PDN connections according to the corresponding IP addresses. The UE22 also divides the respective traffic data flows into the respective PDN connections according to the respective IP addresses. Or,

4. if the UE22 uses a single stack for the PDN connection of the source network, the network element of the network side requests an IPv4 or IPv6 address (the requested IP address type is the same as the IP address type used for the PDN connection of the UE22 in the source network) or the network element of the network side requests a single IP address in the PDN connection establishment procedure initiated by the network element of the network side. Accordingly, PGW14, upon receiving this request, continues to use the IPv4 or IPv6 address assigned by UE22 in the source network.

When a network side network element initiates a PDN connection establishment request and establishes a PDN connection established by UE22 in a source network in a target network, the network side network element sets IP address request indication information in the PDN connection request according to IP address information used by the UE22 in the PDN connection in the source network, IP protocol stack capability type information supported by the PDN connection of the target network and IP protocol stack information supported by the target network, and requests a corresponding IP address. For example:

1. the UE22 uses dual stacks in the source network PDN connection, the IP protocol stack capability type supported by the target network PDN connection is IP dual stack and the IP protocol stack supported by the target network is IPv4/IPv6, and then requests dual IP addresses (IPv4 and IPv6 addresses) in the PDN connection establishment procedure initiated by the network element on the network side. Accordingly, after receiving the request, the PGW continues to use the IPv4 and IPv6 addresses allocated by the UE in the source network; or,

2. the UE22 uses dual stacks in the source network PDN connection, and the IP protocol stack capability type supported by the target network PDN connection is IP dual stack (or IP single stack) but the IP protocol stack supported by the target network is IPv4 or IPv6, then an IPv4 or IPv6 address is requested in the PDN connection establishment procedure initiated by the network-side element, and the requested IP address type is consistent with the IP protocol stack address type supported by the target network. Accordingly, after receiving the request, the PGW continues to use the IPv4 and IPv6 addresses allocated by the UE in the source network; or,

3. the UE uses double stacks in PDN connection of a source network, the IP protocol stack capability type supported by the PDN connection of a target network is IP single stack, but the IP protocol stack supported by the target network is IPv4/IPv6, a network side network element initiates a PDN connection establishment program in the target network for each PDN connection in the source network, and the network side network element requests a single IP address (IPv4 or IPv6 address) in the establishment program. After receiving the request, the PGW continues to use the IPv4 or IPv6 address allocated by the UE in the source network. When the UE finds that the PDN connection only uses one IP address and the original PDN connection has two IP addresses in the received receiving message, the UE initiates a PDN connection establishment program and indicates a network side to allocate another IP address; or,

4. UE uses double stacks in PDN connection of a source network, the IP protocol stack capability type supported by PDN connection of a target network is IP single stack, but the IP protocol stack supported by the target network is IPv4/IPv6, a network side network element initiates two PDN connection establishment procedures in the target network for each PDN connection in the source network, the network side network element requests an IPv4 address in the PDN connection establishment procedure at one time, and the network side network element requests an IPv6 address in the PDN connection establishment procedure at the other time; or,

5. if the UE uses a single stack for the PDN connection of the source network, the network element of the network side requests an IPv4 or IPv6 address (the requested IP address type is the same as the IP address type used for the PDN connection of the UE22 in the source network) or the network element of the network side requests a single IP address in the PDN connection establishment procedure initiated by the network element of the network side. Accordingly, PGW14, upon receiving this request, continues to use the IPv4 or IPv6 address assigned by UE22 in the source network.

In the embodiment, the IP address information is designated by the mobile terminal in the network switching process, so that the IP address distributed by the mobile terminal in the source network can be continuously used in the target network of the mobile terminal.

Fig. 5 is a flowchart of an embodiment of an IP address processing method applied to a UE that needs to be switched to a 3GPP network from a non-3GPP network or a UE that needs to be switched to a 3GPP network from a non-3GPP network during network switching, and specifically includes the following steps:

step 401, UE accesses in non-3 GPP. For the WLAN system, the Non-3GPP Access network element in this step is an Evolved Packet Data Gateway (EPDG); for a Worldwide Interoperability for microwave Access (WiMAX) system, the Non-3GPP Access Network element in this step is an Access Service Network Gateway (ASN GW); for a Code Division Multiple Access (CDMA) system, the Non-3GPP Access network element in this step is an Access Gateway (AGW); for a High Rate Packet Data (HRPD) network, the Non-3gpp access network element in this step is a Packet Data Serving Node (PDSN).

Step 403, the UE decides to switch to the selected target network, such as the 3GPP network, and initiates the handover from the non-3GPP network to the 3GPP network.

Step 405, the UE22 sends an attach request (attach request) message to the mobility management network element through the access network element of the 3GPP network, requesting to switch to the 3GPP network; or the UE22 needs to be handed over to the 3GPP network, but the UE22 also resides in the non-3GPP network, and the UE22 sends the attach request message to the mobility management element through an access element of the non-3GPP network. For a GERAN 18/UTRAN 17 network, the mobility management element is SGSN 19; for the E-UTRAN 1711 network, the mobility management network element is MME 12.

The UE22 may carry IP address request indication information in the attach request message, indicating what address information the network side UE22 needs to acquire. The method specifically comprises the following steps:

the UE22 decides IP address request indication information according to IP address information used by the UE22 in the source network PDN connection. For example:

if the UE22 uses a Dual Stack in the PDN connection of the source network, the UE22 sets the IP address request indication information to a Dual Stack (Dual Stack), that is, the UE22 requests an IPv4 address and an IPv6 address;

the UE22 uses the single stack in the source network PDN connection, the UE22 sets the IP address request indication information to IPv4 or IPv6, and the requested IP address type is the same as the IP address type used by the UE22 in the source network PDN connection.

Or specifically may be:

the UE22 determines the IP address request indication information according to the IP address information used by the UE22 in the source network PDN connection and the IP protocol stack capability type supported by the target network PDN connection. For example:

the UE22 uses double stacks in the PDN connection of the source network, and the IP protocol stack capability type supported by the PDN connection of the target network is IP double stacks, the UE22 sets the IP address request indication information as double stacks, namely the UE22 requests an IPv4 address and an IPv6 address; or,

the UE22 uses double stacks in the PDN connection of the source network, and the IP protocol stack capability type supported by the PDN connection of the target network is single stack, the UE22 sets the IP address request indication information to be IPv4 or IPv 6; or,

the UE22 uses a single stack in the PDN connection of the source network, and the UE22 sets the IP address request indication information to IPv4 or IPv6, where the requested IP address type is consistent with the IP address type used by the UE22 in the source network.

Or specifically may be:

the UE22 determines the IP address request indication information according to the IP address information used by the UE22 in the source network PDN connection, the IP protocol stack capability type information supported by the target network PDN connection, and the IP protocol stack information supported by the target network. For example:

the UE22 uses double stacks in the PDN connection of the source network, the IP protocol stack capability type supported by the PDN connection of the target network is IP double stacks, and the IP protocol stack supported by the PDN connection of the target network is IPv4/IPv6, the UE22 sets the IP address request indication information as double stacks, namely the UE22 requests an IPv4 address and an IPv6 address; or,

the UE22 uses double stacks in the PDN connection of the source network, the IP protocol stack capability type supported by the PDN connection of the target network is IP double stack (or IP single stack) but the IP protocol stack supported by the target network is IPv4 or IPv6, the UE22 sets the IP address request indication information as IPv4 or IPv6, and the requested IP address type is consistent with the IP protocol stack address type supported by the target network; or,

the UE22 uses double stacks in the PDN connection of the source network, the IP protocol stack capability type supported by the PDN connection of the target network is IP single stack, but the IP protocol stack supported by the target network is IPv4/IPv6, and the UE22 sets the IP address request indication information to be IPv4 or IPv 6; or,

the UE22 uses a single stack in PDN connection of a source network, an IP protocol stack supported by a target network is IPv4/IPv6, or the IP protocol stack supported by the target network is IPv4 or IPv6 but the type of the IP protocol stack supported by the target network is consistent with the type of the IP address used by the UE22 in the source network, the UE22 sets IP address request indication information to be IPv4 or IPv6, and the requested IP address type is consistent with the type of the IP address used by the UE22 in the source network. Or,

the UE22 uses a single stack in the PDN connection of the source network, the IP protocol stack supported by the target network is I Pv4 or IPv6, but the IP protocol stack type supported by the target network is inconsistent with the IP address type used by the UE22 in the source network, the UE22 sets the IP address request indication information to be IPv4 or IPv6, and the requested IP address type is consistent with the IP protocol stack type supported by the target network.

The UE22 may carry the IP protocol stack type information supported by the target network in the "Attach Request" message, or

If the IP protocol stack type supported by the target network is IPv4 or IPv6, the UE22 carries the IP protocol stack type information supported by the target network in the 'Attach Request' message. If the UE22 does not carry the IP protocol stack type information supported by the target network in the "Attach Request" message, the network side defaults to the IP protocol stack type information supported by the target network being IPv4/IPv 6.

The IP protocol stack type information supported by the target network may be:

"Network Support IP Address Indicator" cell: if the value of this cell is IPv4, it means that the target network only supports IPv4 addresses; if the value of this cell is IPv6, it means that the target network only supports IPv6 addresses; if the value of the information element is IPv4/IPv6, the information element indicates that the target network supports IPv4 addresses and IPv6 addresses.

Step 407, an Authentication (Authentication) procedure is executed between UE22, the mobility management element, and HSS 16.

Step 409, a Location Update and subscription Data insertion (Update Location and Insert Subscriber Data) procedure is performed between the mobility management network element and the HSS16, the address of the mobility management network element is registered in the HSS16, and the HSS16 inserts the subscription Data of the UE22 into the mobility management network element. In this step, the HSS16 issues PDN connection information used by the UE22 in the non-3GPP network to the mobility management element, that is, the mobility management element obtains APN and PGW14 address information used by the UE22 in the non-3GPP network.

Step 411, if the PDN connection is initiated by the network side network element when the UE22 switches from the non-3GPP network to the 3GPP network or needs to switch, the mobility management network element initiates a PDN connection establishment procedure for each obtained APN and PGW14 address record. If the PDN connection is initiated by the UE22 when the UE22 switches from the non-3GPP network to the 3GPP network or needs to switch, the mobility management element does not initiate the PDN connection establishment procedure or the mobility management element only initiates the default PDN connection (i.e., the PDN connection corresponding to the default APN) establishment procedure.

The mobility management network element sends a Create Default bearer request (Create Default bearer request) message to the SGW13, where the message carries request indication information of PGW14 address, APN, and IP address in the record. If the IP address Request indication information is decided by the UE22, the mobility management element may obtain the IP address Request indication information from an "Attach Request" message sent by the UE 22. If the IP address request indication information is determined by the network side (in this embodiment, by a mobility management network element of the network side), the mobility management network element determines that the IP address request indication information may specifically be:

and the mobility management network element determines IP address request indication information according to the IP address information used by the UE in the PDN connection of the source network. For example,

and the UE uses a double Stack in the PDN connection of the source network, and the mobility management network element sets the IP address request indication information to be the double Stack (Dual Stack, namely the UE requests the IPv4 address and the IPv6 address). Or,

and if the UE uses the single stack in the source network PDN connection, the mobility management network element sets the IP address request indication information to be IPv4 or IPv6, and the requested IP address type is consistent with the IP address type used by the UE22 in the source network PDN connection.

And the mobility management network element determines the IP address request indication information according to the IP address information used by the UE22 in the source network PDN connection and the IP protocol stack capability type supported by the target network PDN connection. For example:

the UE22 uses Dual stacks in the source network PDN connection, and the IP protocol Stack capability type supported by the target network PDN connection is IP Dual stacks, the mobility management network element sets the IP address request indication information to Dual stacks (Dual Stack, that is, the UE22 requests an IPv4 address and an IPv6 address); or,

the UE22 uses double stacks in the PDN connection of the source network, and the IP protocol stack capability type supported by the PDN connection of the target network is single stack, the mobile management network element sets the IP address request indication information to be IPv4 or IPv 6; in the scene, the network side network element initiates a PDN connection establishment program in the target network for each PDN connection in the source network, and the network side network element requests an IPv4 or IPv6 address in the establishment program. Upon receiving this request, the PGW14 continues to use the IPv4 or IPv6 address assigned by the UE22 in the source network. The UE22 finds that this PDN connection only uses one IP address and there are two IP addresses in the original PDN connection in the received acceptance message, the UE22 initiates a PDN connection establishment procedure, instructing the network side to allocate another IP address. Or,

and the UE uses double stacks in PDN connection of a source network, and the IP protocol stack capability type supported by PDN connection of a target network is a single stack, the mobility management network element initiates PDN connection establishment procedures in the target network for each PDN connection in the source network twice, the network side network element in one PDN connection establishment procedure requests an IPv4 address, and the network side network element in the other PDN connection establishment procedure requests an IPv6 address. Or,

and if the UE22 uses the single stack in the source network PDN connection, the mobility management network element sets the IP address request indication information to be IPv4 or IPv6, and the requested IP address type is consistent with the IP address type used by the UE22 in the source network PDN connection.

Or specifically may be: and the mobility management network element determines the IP address request indication information according to the IP address information used by the UE22 in the source network PDN connection, the IP protocol stack capability type information supported by the target network PDN connection and the IP protocol stack information supported by the target network. For example:

the UE22 uses Dual stacks in the PDN connection of the source network, the IP protocol Stack capability type supported by the PDN connection of the target network is IP Dual Stack, and the IP protocol Stack supported by the PDN connection of the target network is IPv4/IPv6, then the mobility management network element sets the IP address request indication information as Dual stacks (Dual Stack, namely the UE22 requests IPv4 address and IPv6 address); or,

the UE22 uses double stacks in the PDN connection of the source network, the IP protocol stack capability type supported by the PDN connection of the target network is IP double stack (or IP single stack) but the IP protocol stack supported by the target network is IPv4 or IPv6, the mobility management network element sets the IP address request indication information as IPv4 or IPv6, and the requested IP address type is consistent with the IP protocol stack address type supported by the target network; or

The UE22 uses double stacks in the PDN connection of the source network, and the IP protocol stack capability type supported by the PDN connection of the target network is single stack, the mobile management network element sets the IP address request indication information to be IPv4 or IPv 6; or,

the UE22 uses double stacks in the PDN connection of the source network, the IP protocol stack capability type supported by the PDN connection of the target network is IP single stack, but the IP protocol stack supported by the target network is IPv4/IPv6, and the mobile management network element sets the IP address request indication information to be IPv4 or IPv 6; in the scene, the network side network element initiates a PDN connection establishment program in the target network for each PDN connection in the source network, and the network side network element requests an IPv4 or IPv6 address in the establishment program. Upon receiving this request, the PGW14 continues to use the IPv4 or IPv6 address assigned by the UE22 in the source network. The UE22 finds that this PDN connection only uses one IP address and there are two IP addresses in the original PDN connection in the received acceptance message, the UE22 initiates a PDN connection establishment procedure, instructing the network side to allocate another IP address. Or,

UE22 uses double stacks in PDN connection of a source network, the IP protocol stack capability type supported by PDN connection of a target network is IP single stack, but the IP protocol stack supported by the PDN connection of the target network is IPv4/IPv6, a network side network element initiates a PDN connection establishment program twice in the target network for each PDN connection in the source network, the network side network element requests an IPv4 address in the PDN connection establishment program once, and the network side network element requests an IPv6 address in the PDN connection establishment program once; or,

the UE22 uses a single stack in PDN connection of a source network, an IP protocol stack supported by a target network is IPv4/IPv6, or the IP protocol stack supported by the target network is IPv4 or IPv6 but the type of the IP protocol stack supported by the target network is consistent with the type of the IP address used by the UE22 in the source network, the mobility management network element sets IP address request indication information to be IPv4 or IPv6, and the requested IP address type is consistent with the type of the IP address used by the UE22 in the source network; or,

the UE22 uses a single stack in the PDN connection of the source network, the IP protocol stack supported by the target network is IPv4 or IPv6, but the IP protocol stack type supported by the target network is not consistent with the IP address type used by the UE22 in the source network, the mobility management network element sets the IP address request indication information to be IPv4 or IPv6, and the requested IP address type is consistent with the IP protocol stack type supported by the target network.

The mobility management network element may obtain, from the IP address request indication information carried in the message sent by the UE22, the IP address information used by the UE22 in the source network PDN connection, or may obtain, from the HSS16, the IP address information used by the UE22 in the source network PDN connection, and in this mechanism, the UE22 is required to register, in the HSS16, the IP address information used by the PDN connection when the PDN connection is established in the source network. When the UE22 establishes a PDN connection in the 3GPP network, the mobility management network element registers the IP address information used by this PDN connection to the HSS 16; when UE22 establishes a PDN connection in a non-3GPP network, PGW14 registers IP address information for use by this PDN connection with HSS 16. The registered IP address information may be: the IP address is indicated as (IPv4 (established PDN connection uses IPv4 address), IPv6 (established PDN connection uses IPv6 address), IPv4/IPv6 (established PDN connection uses IPv4 and IPv6 address) or specific IP address so that the mobility management element can obtain the IP address information used by the PDN connection established by the UE22 in the non-3GPP network from the HSS16 when the UE22 is switched from the non-3GPP network to the 3GPP network or the UE22 needs to be switched from the non-3GPP network to the 3GPP network.

The mobility management element may carry, in the default bearer creation Request message, IP protocol stack type information supported by the target network, where the mobility management element may obtain the information from the Attach Request message, or may obtain the information according to a policy of a target network operator or a capability of the target network. Or, if the IP protocol stack type supported by the target network is IPv4 or IPv6, the mobility management network element may carry the IP protocol stack type information supported by the target network in the create default bearer request message. If the mobility management network element does not carry the IP protocol stack type information supported by the target network in the default bearer creation request message, the network side considers that the IP protocol stack type information supported by the target network is IPv4/IPv6 by default.

Step 413, after receiving the above message, the SGW13 sends a Default Bearer creation Request message (the interface between the SGW13 and the PGW14 uses the GTP protocol) or a proxy binding update message (the interface between the SGW13 and the PGW14 uses the PMIP protocol) (Create Default Bearer Request/ProxyBU) to the PGW14, where the message carries APN and IP address Request indication information. If the mobility management network element carries the IP protocol stack type information supported by the target network in the create default bearer request message, the SGW13 carries this information to the PGW14 in the create default bearer request message or the proxy binding update message.

Step 415, after receiving the above message, the PGW14 locates the PDN connection used by the UE22 according to the APN, and the PGW14 keeps the IP address of the PDN connection unchanged, that is, the PGW14 continues to use the IP address allocated by the UE22 in the non-3GPP network for the PDN connection without allocating the IP address for the PDN connection. The method specifically comprises the following steps:

the UE22 uses IPv4 and IPv6 addresses in the source network PDN connection, and the IP address request indication information in the create default bearer request message or the proxy binding update message received by the PGW14 is dual stack, so that the PGW14 continues to use the IPv4 and IPv6 addresses used by the UE22 in the source network PDN connection in the PDN connection establishment of this time.

Or specifically may be: the UE22 uses IPv4 and IPv6 addresses in the source network PDN connection, and the IP address request indication information in the default bearer creation request message or the proxy binding update message received by the PGW14 is IPv4 or IPv6, so that the PGW14 continues to use the IPv4 or IPv6 address used by the UE22 in the source network in the PDN connection establishment of this time, and the used IP address type is consistent with the IP address type in the IP address request indication information. While PGW14 will continue to retain another IP address that UE22 uses in the source network. The PGW splits the original PDN connection into two PDN connections. The corresponding traffic data flows are divided into the corresponding PDN connections according to the corresponding IP addresses.

Or specifically may be: the UE22 uses IPv4 and IPv6 addresses in the PDN connection of the source network, the IP address request indication information in the create default bearer request message or the proxy binding update message received by the PGW14 is IPv4 or IPv6, and the IP protocol stack supported by the target network is IPv4 or IPv6, then the PGW14 continues to use the IPv4 or IPv6 address used by the UE22 in the source network in the PDN connection establishment of this time, the used IP address type is consistent with the IP address type in the IP address request indication information, and at the same time, the PGW14 deletes another IP address used by the UE22 in the source network, and releases the information used by this IP address (e.g. the TFT used by this address).

The PGW14 returns a create default Bearer Response message or a Proxy binding acknowledgement message (CreateDefault Bearer Response/Proxy BA) to the SGW13, where the message carries the IP address used by the Bearer (or the PDN connection).

In step 417, the SGW13 returns a Create Default bearer response (Create Default bearer response) message to the mobility management element, where the message carries the IP address used by the bearer (or the PDN connection).

Step 419, the mobility management element returns an Attach Accept (Attach Accept) message to the UE22, where the message carries the IP address used by the default bearer (or default PDN connection). The mobility management network element may carry, in the attach accept message, IP protocol stack type information supported by the target network. Or, if the IP protocol stack type supported by the target network is IPv4 or IPv6, the mobility management network element may carry the IP protocol stack type information supported by the target network in the attach accept message. If the mobility management network element does not carry the IP protocol stack type information supported by the target network in the attach accept message, the UE22 considers the IP protocol stack type information supported by the target network as IPv4/IPv6 by default.

Step 421, if the UE22 initiates a PDN connection request (PDN ConnectivityRequest), the UE22 sends a PDN connection request message to the mobility management network element to request establishment of a PDN connection for the PDN connection established by the UE22 in the non-3GPP network. And the message carries APN and IP address request indication information used by PDN connection. The process of the UE22 deciding the IP address request indication information is described in step 405. The UE22 may carry IP protocol stack type information supported by the target network in the PDN connectivity request message. Or

If the IP protocol stack type supported by the target network is IPv4 or IPv6, the UE22 carries the IP protocol stack type information supported by the target network in the PDN connection request message. If the UE22 does not carry the IP protocol stack type information supported by the target network in the PDN connection request message, the network side considers that the IP protocol stack type information supported by the target network is IPv4/IPv6 by default.

If the UE22 uses IPv4 and IPv6 addresses in the source network and the IP protocol stack capability type supported by the PDN connection of the target network is IP single stack, the UE22 sends two PDN connection request messages to the mobility management network element for one PDN connection of the source network, the IP address request indication information in one PDN connection request message is set to be IPv4, and the IP address request indication information in the other PDN connection request message is set to be IPv 6.

If the PDN connection is initiated by the network side by the UE22 at the non-3GPP to 3GPP handover or when a handover is required, and the UE22 finds that the PDN connection established on the network side uses only one IP address and that the PDN connection established by the UE22 in the source network PDN connection uses two IP addresses, the UE22 initiates a PDN connection establishment procedure, instructing the network side to allocate to this PDN connection another IP address allocated by the UE22 in the source network PDN connection. If the PDN connection established in the PDN connection establishment procedure initiated by the network side uses an IPv4 address, the UE22 sends a PDN connection request message to the mobility management network element, and the UE22 sets the IP address request indication information in the message to be IPv 6. The network side thus assigns the IPv6 address assigned by the UE22 in the source network PDN connection to this PDN connection.

If the UE22 initiates a PDN connection at the non-3GPP to 3GPP handover or handover is required, and the UE22 finds that the PDN connection established at the network side uses only one IP address and the network side informs the UE22 that the IP protocol stack supported by the target network is a single stack, if the PDN connection established by the UE22 in the PDN connection of the source network uses two IP addresses, the UE22 deletes the other IP address allocated in the PDN connection of the source network, and deletes information used by this IP address (e.g. TFT used by this address).

Step 423, after receiving the message, the mobility management network element obtains the PGW address corresponding to the APN according to the APN query record carried in the message. The mobility management network element sends a Create Default Bearer Request (Create Default Bearer Request) message to the SGW13 to Request PDN connection creation, where the message carries Request indication information of a PGW address, an APN, and an IP address in a record. If the IP address Request indication information is decided by the UE22, the mobility management network element may obtain the IP address Request indication information from a PDN Connection Request message sent by the UE 22. If the IP address request indication information is determined by the network side (in this embodiment, by a mobility management network element of the network side), the method for the mobility management network element to determine the IP address request indication information is the same as the processing in step 6, and details are not described here.

The mobility management network element may carry, in the default bearer creation request message, IP protocol stack type information supported by the target network, where the mobility management network element may obtain the information from the PDN ConnectionRequest message, or may obtain the information according to a policy of a target network operator or a capability of the target network.

The processing from step 425 to step 429 as well as the processing from step 413 to step 417 are not described herein again.

And step 431, the mobility management network element returns a PDN connection acceptance message to the UE22, where the message carries the IP address used by the PDN connection.

In this embodiment, in the network handover process, the IP address information is specified by the mobile terminal or the mobility management network element, so that the UE can continue to use the IP address allocated by the UE in the non-3GPP network in the 3GPP network.

Fig. 6 is a flowchart of an embodiment of an IP address processing method for network handover in the case of handover from a 3GPP network to a Non-3GPP network or handover from a 3GPP network to a Non-3GPP network, where in this embodiment, a proxy mobile IP (ProxyMIP, PMIP) protocol is used between a Non-3GPP Access network element and a PGW, and the network handover specifically includes:

step 501, the UE22 accesses in 3 GPP. The UE22 decides to handover to a selected target network, such as a non-3GPP network, and initiates a handover between the 3GPP network and the non-3GPP network.

Step 503, the UE22 switches to the non-3GPP network, and performs Authentication and Authorization (Authentication & Authorization) through the access network element of the non-3GPP network; or the UE22 needs to be handed over to the non-3GPP network, but the UE22 also resides in the 3GPP network, and the UE22 performs authentication and authorization through an access network element of the 3GPP network. For the WLAN system, the Non-3gpp access network element is an EPDG (Evolved Packet Data Gateway); for the Wimax system, the Non-3GPP Access Network element is an ASN GW (Access Service Network Gateway); for CDMA systems, the Non-3gpp Access network element is an AGW (Access Gateway). The Non-3GPP Access network element obtains PDN connection information used by the UE22 in the 3GPP network in this step, that is, the Non-3GPP Access network element obtains an APN and a PGW address used by the UE22 in the 3GPP network.

Step 505, the UE22 sends a layer 3 Attach Request message (L3 Attach Request) to the Non-3GPP Access network element through the Access network element of the Non-3GPP network or the Access network element of the 3GPP network.

The UE22 may carry IP address request indication information in the layer 3 attach request message to indicate what address information the UE22 needs to acquire on the network side. The method for UE22 to determine the IP address request indication information is the same as the processing in the embodiment shown in fig. 5, and is not described herein again.

The UE22 may carry the IP protocol stack type information supported by the target network in the layer 3 attach request message, or

If the IP protocol stack type supported by the target network is IPv4 or IPv6, the UE22 carries the IP protocol stack type information supported by the target network in the layer 3 attach request message. If the UE22 does not carry the IP protocol stack type information supported by the target network in the layer 3 attach request message, the network side determines that the IP protocol stack type information supported by the target network is IPv4/IPv 6.

Step 507, if the PDN connection establishment procedure of the UE22 at the time of 3GPP to non-3GPP handover or handover required is initiated by the network side, step 507, step 509 is performed. The Non-3GPP access network element initiates a PDN connection establishment procedure for each PDN connection established by the UE22 in the 3GPP network, sending a Proxy binding update (Proxy BU) message to the PGW 14. And the message carries APN and IP address request indication information used by PDN connection. The processing of the Non-3GPP Access network element determining the IP address request indication information and the processing of the PDN connection establishment are the same as those in the embodiment shown in fig. 5.

The Non-3GPP Access network element can carry IP protocol stack type information supported by the target network in the proxy binding update message, or

And if the IP protocol stack type supported by the target network is IPv4 or IPv6, the Non-3GPPAccess network element carries the IP protocol stack type information supported by the target network in the proxy binding update message. And if the Non-3GPP Access network element does not carry the IP protocol stack type information supported by the target network in the proxy binding update message, the network side confirms that the IP protocol stack type information supported by the target network is IPv4/IPv 6.

And the Non-3GPP Access network element acquires the IP protocol stack type supported by the target network according to the strategy of the target network operator or the capability of the target network.

In step 509, after receiving the above message, the PGW14 locates the PDN connection used by the UE22 according to the APN, and the PGW14 keeps the IP address of the PDN connection unchanged, that is, the PGW14 continues to use the IP address allocated by the UE22 in the 3GPP network for the PDN connection without allocating the IP address to the PDN connection. The method specifically comprises the following steps:

the UE22 uses IPv4 and IPv6 addresses in the source network PDN connection, and the IP address request indication information in the proxy binding update message received by the PGW14 is dual stack, so that the PGW14 continues to use the IPv4 and IPv6 addresses used by the UE22 in the source network PDN connection during this PDN connection establishment.

Or specifically may be: the UE22 uses IPv4 and IPv6 addresses in the source network PDN connection, and the IP address request indication information in the proxy binding update message received by the PGW14 is IPv4 or IPv6, so that the PGW14 continues to use the IPv4 or IPv6 address used by the UE22 in the source network PDN connection in the PDN connection establishment of this time, and the used IP address type is consistent with the IP address type in the IP address request indication information. While PGW14 will continue to retain another IP address that UE22 uses in the source network. The PGW splits the original PDN connection into two PDN connections. The corresponding traffic data flows are divided into the corresponding PDN connections according to the corresponding IP addresses.

Or specifically may be: the UE22 uses IPv4 and IPv6 addresses in the PDN connection of the source network, the IP address request indication information in the proxy binding update message received by the PGW14 is IPv4 or IPv6, and the IP protocol stack supported by the target network is IPv4 or IPv6, then the PGW14 continues to use the IPv4 or IPv6 address used by the UE22 in the source network in the PDN connection establishment of this time, the used IP address type is consistent with the IP address type in the IP address request indication information, and at the same time, the PGW14 deletes another IP address used by the UE22 in the source network, and releases the information used by this IP address (e.g. the TFT used by this address).

The PGW14 returns a Proxy binding acknowledgement (Proxy BA) message to the Non-3GPP Access network element, where the message carries the IP address used by the bearer (or the PDN connection).

Step 511, the Non-3GPP Access network element returns a layer 3 Attach Accept (L3 Attach Accept) message to the UE.

Step 513, if a PDN connection establishment procedure (PDN Connectivity Request) of the UE22 at the time of the 3GPP to non-3GPP handover or handover required is initiated by the UE22, steps 513 to 513 are performed. For each PDN connection established by the UE22 in the 3GPP network, the UE22 sends a PDN connection request message to the Non-3GPP Access network element through the Non-3GPP network or an Access network element of the 3GPP network to request establishment of the PDN connection. And the message carries APN and IP address request indication information used by PDN connection. The process of the UE22 deciding the IP address request indication information is described in the embodiment shown in fig. 4.

The UE22 may carry the IP protocol stack type information supported by the target network in the PDN connectivity request message, or

If the IP protocol stack type supported by the target network is IPv4 or IPv6, the UE22 carries the IP protocol stack type information supported by the target network in the PDN connection request message. If the UE22 does not carry the IP protocol stack type information supported by the target network in the PDN connection request message, the network side confirms that the IP protocol stack type information supported by the target network is IPv4/IPv 6.

If the IP protocol stack capability type supported by the PDN connection of the target network is IP single stack, the UE22 uses IPv4 and IPv6 addresses in the source network, and the UE22 sends two PDN connection request messages to a Non-3GPP Access network element to one PDN connection of the source network, wherein the IP address request indication information in one PDN connection request message is set to be IPv4, and the IP address request indication information in the other PDN connection request message is set to be IPv 6.

And step 515, after receiving the message, the Non-3GPP accesses network element acquires the PGW address corresponding to the APN according to the APN query record carried in the message. The Non-3GPP Access network element sends a Proxy binding update (Proxy BU) message to a PGW to request PDN connection establishment, wherein the message carries APN and IP address request indication information. The processing of the Non-3GPP Access network element determining the IP address request indication information is the same as the processing in the embodiment shown in fig. 4. The Non-3GPP Access network element may carry, in the proxy binding update message, IP protocol stack type information supported by the target network, where the Non-3GPP Access network element may obtain the information from the PDN connection request message, or may obtain the information according to a policy of a target network operator or a capability of the target network.

Step 517 may synchronize the processing of step 509.

Step 519, the mobility management element returns a PDN connection accept (PDN ConnectivityAccept) message to the UE22, where the message carries the IP address used by the PDN connection.

In this embodiment, the PGW obtains the specified IP address information through the layer 3 attach request message or the PDN connection request message, and performs network handover according to the specified IP address information, thereby implementing that the UE can continue to use the IP address allocated by the mobile terminal in the 3GPP network in the non-3GPP network.

Fig. 7 is a flowchart of another embodiment of the IP Address processing method for handover of the UE from the 3GPP network to the non-3GPP network or handover of the UE from the 3GPP network to the non-3GPP network in the network handover of the present invention, in this embodiment, a Dual-Stack mobile IPv6(DSMIPv6, Dual-Stack MIPv6) protocol or MIPv4 FACoA (mobile IPv4 Foreign Agent forward Address, MIPv4 forward Agent Care-of-Address) protocol is used between the UE22 and the PGW. The switching process specifically includes:

step 601, UE22 accesses in 3 GPP. The UE22 switches to a selected target network, such as a non-3GPP network, and initiates a handover (UE initial HO) between the 3GPP network and the non-3GPP network.

Step 603, the UE22 switches to the non-3GPP network, and performs Authentication and Authorization (Authentication & Authorization) through the access network element of the non-3GPP network; or the UE22 needs to be handed over to the non-3GPP network, but the UE22 also resides in the 3GPP network, and the UE22 performs authentication and authorization through an access network element of the 3GPP network. For the WLAN system, the Non-3gpp access network element is an Evolved Packet Data Gateway (EPDG); for the Wimax system, the Non-3GPP Access Network element is an Access service Network Gateway (ASN GW); for the CDMA system, the Non-3GPP Access network element is an Access Gateway (AGW). The Non-3GPP Access network element obtains PDN connection information used by the UE22 in the 3GPP network in this step, that is, the Non-3GPP Access network element obtains an APN and a PGW address used by the UE22 in the 3GPP network.

Step 605, the UE22 sends a layer 3 Attach Request (L3 Attach Request) message to the Non-3GPP Access network element through the Access network element of the Non-3GPP network or the Access network element of the 3GPP network.

Step 607, the Non-3GPP Access network element returns a layer 3 Attach Accept (L3 Attach Accept) message to the UE 22.

Step 609, for each PDN connection established by the UE22 in the 3GPP network, the UE22 sends a Binding Update (Binding Update) message to the PGW14 through an access network element of the non-3GPP network or an access network element of the 3GPP network to request establishment of the PDN connection. And the message carries APN and IP address request indication information used by PDN connection. The process of the UE22 deciding the IP address request indication information is described in the embodiment shown in fig. 4.

The UE22 may carry the IP protocol stack type information supported by the target network in the binding update message, or

If the IP protocol stack type supported by the target network is IPv4 or IPv6, the UE22 carries the IP protocol stack type information supported by the target network in the binding update message. If the UE22 does not carry the IP protocol stack type information supported by the target network in the binding update message, the network side confirms that the IP protocol stack type information supported by the target network is IPv4/IPv 6.

If the UE22 uses IPv4 and IPv6 addresses at the source network PDN connection and the IP protocol stack capability type supported by the target network PDN connection is IP single stack, the UE22 sends two binding update messages to a Non-3GPP Access network element to one PDN connection of the source network PDN connection, the IP address request indication information in one binding update is set to be IPv4, and the IP address request indication information in the other binding update message is set to be IPv 6.

Step 611, after receiving the above message, the PGW14 locates the PDN connection used by the UE22 according to the APN, and the PGW14 keeps the IP address of the PDN connection unchanged, that is, the PGW14 continues to use the IP address allocated by the UE22 in the 3GPP network for the PDN connection without allocating the IP address for the PDN connection. The subsequent processing is the same as in the embodiment shown in fig. 5.

The PGW14 sends back a Binding acknowledgement (Binding acknowledgement) message to the UE22, which carries the IP address used for this PDN connection.

In this embodiment, the non-3GPP gateway obtains the specified IP address information through the binding update message, and performs network handover according to the specified IP address information, thereby implementing that the UE can continue to use the IP address allocated by the mobile terminal in the 3GPP network in the non-3GPP network.

Note: embodiments of the present invention are described in terms of handover between a 3GPP network and a non-3GPP network, but the mechanisms of the present invention are equally applicable to handover between 3GPP networks or handover between non-3GPP networks.

Fig. 8 is a schematic structural diagram of an embodiment of a network selection system according to the present invention, which includes a user equipment 31 and an access network discovery and selection function ANDSF network element 32, where the user equipment 31 obtains available access network information from the ANDSF network element 32, and selects a target network from available access networks according to IP address information used by the user equipment 31 in a source network and the available access network information; or the ANDSF network element 32 obtains the IP address information of the user equipment 31 in the source network according to the reported information of the user equipment 31, and selects the target network from the available access networks according to the IP address information and the available access network information of the user equipment 31 used in the source network. The detailed process is detailed in the embodiment of the network selection method.

In this embodiment, the network selection system selects a target network with the same capability as the IP address of the source network from the available access networks through the user equipment or the ANDSF network element, so that the user equipment realizes the optimal selection of the target network, and ensures that the IP address used by the mobile terminal in the source network can be continuously used in the target network.

Fig. 9 is a schematic structural diagram of an embodiment of a mobile terminal of the present invention, and as shown in fig. 9, the mobile terminal includes an available access network information obtaining unit 33 and a selecting unit 34, where the available access network information obtaining unit 33 is configured to obtain available access network information from an ANDSF network element on a network side, where the available access network information may include an IP protocol stack supported by an available access network and/or an IP protocol stack capability type supported by an available access network packet data network PDN connection; the selection unit 34 selects a target network from the available access networks based on the IP address information used by the user equipment in the source network and the available access network information acquired by the available access network information acquisition unit 33.

The selecting unit 34 may include an IP protocol stack acquiring subunit and a target selecting subunit, where the IP protocol stack acquiring subunit acquires, from the available access network information, an IP protocol stack supported by an available access network; and the target selection subunit selects the target network according to the IP protocol stack supported by the available access network and the IP address information used by the user equipment in the source network.

Or, the selecting unit 34 may include an IP protocol stack capability type obtaining subunit and a target selecting subunit, where the IP protocol stack capability type obtaining subunit obtains, from the available access network information, an IP protocol stack capability type supported by the PDN connection of the available access network; and the target selection subunit selects a target network according to the IP protocol stack capability type supported by the PDN connection of the available access network and the IP address information used by the user equipment in the source network.

Or, the selecting unit 34 may include a protocol stack and capability type obtaining subunit and a target selecting subunit, where the protocol stack and capability type obtaining subunit obtains, from the available access network information, an IP protocol stack capability type supported by the PDN connection of the available access network and an IP protocol stack supported by the available access network; and the target selection subunit selects the target network according to the IP protocol stack capability type supported by the PDN connection of the available access network, the IP protocol stack supported by the available access network and the IP address information used by the user equipment in the source network.

In this embodiment, the mobile terminal obtains the information of the available access network through the information obtaining unit of the available access network, and the selecting unit selects the target network according to the information of the available access network and the IP address information used by the mobile terminal in the source network, so that the mobile terminal can preferentially select the target network with the same capability as the IP address of the source network, and the IP address used by the mobile terminal in the source network can be ensured to be continuously used in the target network.

Fig. 10 is a schematic structural diagram of an embodiment of the IP address processing system of the present invention, which includes an IP address obtaining unit 41, a target IP specifying unit 42, and a specifying notifying unit 43; the IP address obtaining unit 41 is configured to obtain IP address information used by the user equipment in the source network; the target IP specifying unit 42 is configured to specify, according to the IP address information used by the user equipment in the source network, the IP address information used by the user equipment in the target network; the designation notifying unit 43 is configured to send the designated IP address information to the user plane anchor gateway.

The IP address obtaining unit 31 may be a mobility management network element in a 3GPP network or a network element in a non-3GPP network, and obtains the IP address information used by the user equipment in the source network from the home subscriber server HSS.

The target IP specifying unit 32 may include: the system comprises a capability type acquisition subunit and a first appointed subunit, wherein the capability type acquisition subunit is used for acquiring the IP protocol stack capability type supported by the PDN connection of the target network; the first appointing subunit is used for appointing the IP address information used by the user equipment in the target network according to the IP address information used by the user equipment in the source network and the IP protocol stack capability type supported by the PDN connection of the target network;

or may include: the protocol stack acquisition subunit is used for acquiring the IP protocol stack supported by the target network; the second appointing subunit is used for appointing the IP address information used by the user equipment in the target network according to the IP address information used by the user equipment in the source network and the IP protocol stack supported by the target network;

or may include: a capability type and protocol stack acquiring subunit and a third specifying subunit, where the capability type and protocol stack acquiring subunit may include a capability type acquiring subunit and a protocol stack acquiring subunit, and is used to acquire an IP protocol stack capability type supported by the PDN connection of the target network and an IP protocol stack supported by the target access network; and the third appointing subunit is used for appointing the IP address information used by the user equipment in the target network according to the IP address information used by the user equipment in the source network, the IP protocol stack supported by the target network and the IP protocol stack capability type supported by the PDN connection of the target network.

The IP address processing system during network switching may further include a mobility management network element or a user plane anchor gateway in the source network, and register the IP address information used by the user equipment in the source network to a home subscriber server HSS.

In this embodiment, the IP address processing system specifies the IP address information in the network handover process through the target IP specifying unit, so that the mobile terminal continues to use the IP address allocated by the UE in the source network in the target network.

Those of ordinary skill in the art will understand that: all or part of the steps for implementing the method embodiments may be implemented by hardware related to program instructions, and the program may be stored in a computer readable storage medium, and when executed, the program performs the steps including the method embodiments; and the aforementioned storage medium includes: various media that can store program codes, such as ROM, RAM, magnetic or optical disks.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. A network selection method, comprising:

acquiring IP address information and/or available access network information;

2. The method of claim 1, wherein obtaining IP address information and/or available access network information comprises:

and acquiring the available access network information from the network side.

3. The method of claim 2, wherein selecting the target network from the available access networks according to the IP address information used by the user equipment in the source network and the available access network information comprises:

acquiring an IP protocol stack supported by an available access network from the available access network information;

selecting a target network according to an IP protocol stack supported by the available access network and IP address information used by the user equipment in a source network;

or comprises the following steps:

acquiring the IP protocol stack capability type supported by the PDN connection of the available access network from the information of the available access network;

selecting a target network according to the IP protocol stack capability type supported by the PDN connection of the available access network and the IP address information used by the user equipment in the source network;

or comprises the following steps:

acquiring the IP protocol stack capability type supported by the PDN connection of the available access network and the IP protocol stack supported by the available access network from the information of the available access network;

and selecting a target network according to the IP protocol stack capability type supported by the PDN connection of the available access network, the IP protocol stack supported by the available access network and the IP address information used by the user equipment in the source network.

4. The method of claim 1, wherein obtaining IP address information and/or available access network information comprises:

and acquiring IP address information used by the user equipment in a source network from the user equipment.

5. The method of claim 4, wherein selecting the target network from the available access networks according to the IP address information used by the user equipment in the source network and the available access network information comprises:

selecting a target network according to an IP protocol stack supported by an available access network in the available access network information and IP address information used by the user equipment in a source network;

or comprises the following steps:

selecting a target network according to the IP protocol stack capability type supported by the PDN connection of the available access network in the information of the available access network and the IP address information used by the user equipment in the source network;

or comprises the following steps:

and selecting a target network according to the IP protocol stack capability type supported by the PDN connection of the available access network in the available access network information, the IP protocol stack supported by the available access network in the available access network information and the IP address information used by the user equipment in the source network.

6. An IP address processing method during network switching is characterized by comprising the following steps:

acquiring IP address information used by user equipment in a source network;

7. The method for processing the IP address during the network handover as claimed in claim 6, wherein the obtaining the IP address information used by the ue in the source network specifically comprises:

a mobility management network element in a third generation partnership project (3 GPP) network or a gateway in a non-3GPP network acquires IP address information used by the user equipment in a source network from a Home Subscriber Server (HSS).

8. The method for processing the IP address during the network switching according to claim 6, wherein the method further comprises:

and a mobility management network element or a user plane anchor point gateway in the source network registers the IP address information used by the user equipment in the source network to a Home Subscriber Server (HSS).

9. The method for processing the IP address during the network switching according to claim 6, further comprising:

acquiring the IP protocol stack capability type supported by the PDN connection of the target network;

according to the IP address information used by the user equipment in the source network, the step of appointing the IP address information used by the user equipment in the target network comprises the following steps:

and appointing the IP address information used by the user equipment in the target network according to the IP address information used by the user equipment in the source network and the IP protocol stack capability type supported by the PDN connection of the target network.

10. The method for processing the IP address during the network switching according to claim 6, further comprising: acquiring an IP protocol stack supported by the target network;

and according to the IP address information used by the user equipment in the source network and the IP protocol stack supported by the target network, the IP address information used by the user equipment in the target network is appointed.

11. The method for processing the IP address during the network switching according to claim 6, further comprising:

acquiring the IP protocol stack capability type supported by the PDN connection of the target network and the IP protocol stack supported by the target access network;

and appointing the IP address information used by the user equipment in the target network according to the IP address information used by the user equipment in the source network, the IP protocol stack supported by the target network and the IP protocol stack capability type supported by the PDN connection of the target network.

12. A mobile terminal, comprising:

an available access network information obtaining unit, configured to obtain available access network information from a network side;

13. The mobile terminal according to claim 12, wherein the selecting unit comprises:

an IP protocol stack obtaining subunit, configured to obtain, from the available access network information, an IP protocol stack supported by an available access network;

and the target selection subunit is used for selecting the target network according to the IP protocol stack supported by the available access network and the IP address information used by the user equipment in the source network.

14. The mobile terminal according to claim 12, wherein the selecting unit comprises:

an IP protocol stack capability type obtaining subunit, configured to obtain, from the available access network information, an IP protocol stack capability type supported by an available access network PDN connection;

and the target selection subunit is used for selecting a target network according to the IP protocol stack capability type supported by the PDN connection of the available access network and the IP address information used by the user equipment in the source network.

15. The mobile terminal according to claim 12, wherein the selecting unit comprises:

a protocol stack and capability type obtaining subunit, configured to obtain, from the available access network information, an IP protocol stack capability type supported by an available access network PDN connection and an IP protocol stack supported by an available access network;

and the target selection subunit is used for selecting a target network according to the IP protocol stack capability type supported by the PDN connection of the available access network, the IP protocol stack supported by the available access network and the IP address information used by the user equipment in the source network.

16. A network selection system comprising a user equipment, an Access network discovery and selection function, ANDSF, network element, characterized in that,

the ANDSF network element is used for providing available access network information;

the user equipment is used for acquiring available access network information from the ANDSF network element and selecting a target network from available access networks according to the IP address information used by the user equipment in a source network and the available access network information.

17. A network selection system comprising a user equipment, an Access network discovery and selection function, ANDSF, network element, characterized in that,

the user equipment is used for reporting information;

18. An IP address processing system, comprising:

19. The IP address processing system of claim 18, wherein the IP address obtaining unit is a mobility management network element in a 3GPP network or a gateway in a non-3GPP network, and is configured to obtain the IP address information used by the user equipment in the source network from a home subscriber server HSS.

20. The IP address processing system of claim 18, further comprising a mobility management network element or a user plane anchor gateway in the source network, configured to register IP address information used by the user equipment in the source network with a home subscriber server HSS.

21. The IP address processing system of claim 18, wherein the target IP designation unit comprises:

a capability type obtaining subunit, configured to obtain an IP protocol stack capability type supported by the PDN connection of the target network;

a first specifying subunit, configured to specify, according to the IP address information used by the user equipment in the source network and an IP protocol stack capability type supported by the PDN connection of the target network, the IP address information used by the user equipment in the target network.

22. The IP address processing system of claim 18, wherein the target IP designation unit comprises:

a protocol stack obtaining subunit, configured to obtain an IP protocol stack supported by the target network;

and the second appointing subunit is used for appointing the IP address information used by the user equipment in the target network according to the IP address information used by the user equipment in the source network and the IP protocol stack supported by the target network.

23. The IP address processing system of claim 18, wherein the target IP designation unit comprises:

a capability type and protocol stack obtaining subunit, configured to obtain an IP protocol stack capability type supported by the PDN connection of the target network and an IP protocol stack supported by the target access network;

and the third appointing subunit is used for appointing the IP address information used by the user equipment in the target network according to the IP address information used by the user equipment in the source network, the IP protocol stack supported by the target network and the IP protocol stack capability type supported by the PDN connection of the target network.