CN106792936B

CN106792936B - PGW switching method and communication equipment for maintaining service continuity

Info

Publication number: CN106792936B
Application number: CN201611123209.2A
Authority: CN
Inventors: 张�浩; 王国骄; 郁春波
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2016-12-08
Filing date: 2016-12-08
Publication date: 2020-04-03
Anticipated expiration: 2036-12-08
Also published as: CN106792936A

Abstract

The invention discloses a PGW switching method for maintaining service continuity, which comprises the following steps: the MME determines a target PGW and a target SGW, and sends a first creating session request comprising a downlink endpoint address carried by a first S1 to the target SGW, so that the target SGW and the target PGW configure an endpoint address carried by a second S1 and an endpoint address carried by a second S5/S8 respectively, and allocate a second IP address to the UE; and after the UE resets the IP address, the eNB modifies the S1 bearer of the uplink data channel from the first S1 bearer to a second S1 bearer. The invention also provides related communication equipment capable of realizing the method. The invention can keep the service continuity when switching the PGW.

Description

PGW switching method and communication equipment for maintaining service continuity

Technical Field

The present invention relates to the field of communications, and in particular, to a PGW handover method and a communications device for maintaining service continuity.

Background

With the popularization of mobile internet applications, the limitations of existing internet protocols, such as Transmission Control Protocol (TCP) or User Datagram Protocol (UDP), become more and more obvious. For example, when a terminal is switched from a Wireless-Fidelity (Wi-Fi) to a cellular network, a network Interconnection Protocol (IP) address needs to be reallocated, and an original service connection is interrupted and lost. Therefore, in the prior art, a Quick User Datagram Internet Connection (QUIC) Protocol is formulated, and a Connection Identifier (CID) is defined in a transport layer to uniquely identify a session Connection between a current application client (App) and an application server (App server), so as to separate a location identifier IP from an identity identifier CID. Even if the IP address of the terminal changes, the session can be resumed by the CID without re-establishing the connection.

A method for supporting a gateway node reselection at handover is provided in the patent "a method for supporting a gateway node reselection" (application number CN 201010162474), which is roughly as follows: in the process that a terminal is switched from a source base station to a target base station, firstly, the source base station sends a switching request message to the target base station, wherein the switching request message comprises information for the target base station to perform access control judgment; the target base station makes access control judgment according to the information provided by the source base station, if the judgment cannot ensure that the switching is successful, the judgment is that the switching is failed, and a switching preparation failure message is sent to the source base station; after receiving the switching preparation failure message, the source base station requests a core network node to initiate a PDN connection release process; after the PDN connection release procedure is completed, the UE initiates a PDN connection establishment request to the MME, and after the MME receives the PDN connection establishment request, the MME reselects a PGW for the UE according to subscription information of the UE and information of a currently accessed base station, and continues to complete the entire PDN connection establishment procedure, as shown in fig. 1.

However, in the PGW reselection process, the UE needs to release the original PDN connection first and then establish a new PDN connection. When the original PDN connection is released, the original service connection is interrupted and lost.

Disclosure of Invention

The invention provides a PGW switching method and communication equipment for maintaining service continuity, which can maintain service continuity when switching PGW.

In a communication system applied by the method, a PDN connection is established between the UE and an application server, where the PDN connection includes a first IP address of the UE, the eNB and the source SGW establish a first S1 bearer for the PDN connection, and the source SGW and the source PGW establish a first S5/S8 bearer for the PDN connection. The method comprises the following steps: the MME determines a target PGW and a target SGW, wherein the target PGW is a PGW redistributed by the MME for PDN connection, and the target SGW is an SGW redistributed by the MME for PDN connection. The MME sends a first creation session request comprising a downlink endpoint address carried by the first S1 to a target SGW, the target SGW configures an uplink endpoint address carried by the second S1 and a downlink endpoint address carried by the second S5/S8 according to the first creation session request, sends a second creation session request to a target PGW, the target PGW configures an uplink endpoint address carried by the second S5/S8 and allocates a second IP address for the UE according to the second creation session request, and sends the uplink endpoint address carried by the second S5/S8 and the second IP address to the target SGW. After receiving a first created session response which is sent by the target SGW and comprises an uplink endpoint address and a second IP address of a second S1 bearer, the MME sends a PDN connection modification request which comprises the uplink endpoint address and the second IP address of the second S1 bearer to the eNB, the eNB sends the second IP address to the UE, and after the UE modifies the first IP address into the second IP address, the eNB modifies the S1 bearer of the uplink data channel from the first S1 bearer into a second S1 bearer according to the uplink endpoint address of the second S1 bearer; and the MME receives the PDN connection modification response sent by the eNB. According to the implementation, the UE and the application server can keep the original session connection when the PGW and the SGW are switched, and the problem that the original service connection is interrupted due to PGW switching in the prior art is solved.

In a possible implementation manner of the first aspect, after the MME receives a PDN connection modification response sent by the eNB, the MME sends, to the source SGW, a first delete session request including a bearer identifier, where the bearer identifier corresponds to the first S1 bearer and the first S5/S8 bearer, so that the source SGW sends, to the source PGW, a second delete session request including the bearer identifier, where the second delete session request is used to instruct the source PGW to delete an uplink endpoint address of the first S5/S8 bearer and release the first IP address; the MME receives a first session deletion response sent by the source SGW, and the first session deletion response is generated by the source SGW after receiving a second session deletion response sent by the source PGW. By this implementation, after the PDN connection provided by the source SGW and the source PGW for the UE fails, the source SGW and the source PGW can release the original IP address, thereby saving network resources.

In another possible implementation manner of the first aspect, the determining, by the MME, the target PGW may specifically be: the MME selects a target PGW from the candidate PGWs according to at least one item of service statistical information, network topology, load balance, internal events or access point names; and/or the MME determining the target SGW may specifically be: the MME selects a target SGW from the candidate SGWs according to at least one of network topology, load balancing or internal events. By this implementation, the MME can schedule the service carried by the PGW or the SGW in the communication network, thereby implementing network load balancing.

In a communication system applied by the method, a PDN connection is established between the UE and an application server, where the PDN connection includes a first IP address of the UE, the eNB and the source SGW establish a first S1 bearer for the PDN connection, and the source SGW and the source PGW establish a first S5/S8 bearer for the PDN connection. The method comprises the following steps: the UE receives a PGW reconfiguration notification including the second IP address from the eNB; and the UE generates an IP reconfiguration notice comprising the second IP address and the connection identifier, and sends the IP reconfiguration notice to the application server, and the application server keeps session connection with the UE according to the second IP address and the connection identifier. The UE then sends a PGW reconfiguration notification acknowledgement message to the eNB. Wherein the second IP address is allocated for the UE by a target PGW different from the source PGW. By the implementation, after the UE receives the new IP address, the original session connection can be maintained with the application server through the new IP address and the connection identifier.

In a possible implementation manner of the second aspect, the UE receives a PGW reconfiguration notification including the second IP address from the eNB through an RRC layer of a control plane protocol stack of the UE, acquires an IP available notification including the second IP address from the RRC layer of the control plane protocol stack of the UE through an STP layer of a user plane protocol stack of the UE, generates an IP reconfiguration notification including the second IP address and the connection identifier, and sends the IP reconfiguration notification to the STP layer of the application server through the STP layer of the user plane protocol stack of the UE. And in this way, the UE transmits the new IP address on the control plane and the user plane, and then performs session connection with the application server through the new IP address.

In another possible implementation manner of the second aspect, after the UE receives the PGW reconfiguration notification sent by the eNB, the UE deactivates the first IP address. By this implementation, the UE may deactivate the first IP address after the first IP address fails, so as to save network resources.

In another possible implementation manner of the second aspect, the sending, by the UE, the PGW reconfiguration notification acknowledgment message to the eNB may specifically be: when the UE receives a PGW reconfiguration notification sent by the eNB, starting a timer; and when the timing duration of the timer is not less than the preset duration, the UE sends a PGW reconfiguration notification confirmation message to the eNB. By this implementation, the UE can notify the eNB of the bearer handover without receiving the IP reconfiguration notification acknowledgement message sent by the application server.

In another possible implementation manner of the second aspect, the sending, by the UE, the PGW reconfiguration notification acknowledgment message to the eNB may specifically be: and when the UE receives the IP reconfiguration notification confirmation message sent by the application server, the UE sends a PGW reconfiguration notification confirmation message to the eNB. In this way, when the application server confirms that the session remains connected, the UE notifies the eNB of the bearer switching.

A third aspect provides a PGW handover method for maintaining service continuity, where in a communication system applied in the method, a UE establishes a PDN connection with an application server, the PDN connection includes a first internet IP address of the UE, an eNB establishes a first S1 bearer with a source SGW for the PDN connection, and the source SGW establishes a first S5/S8 bearer with the source PGW for the PDN connection, and the method includes: the target PGW receives a second creation session request which is sent by a target SGW different from the source SGW and comprises a downlink endpoint address carried by a second S5/S8; the target PGW configures the uplink endpoint address carried by the second S5/S8 according to the second creating session request, and allocates a second IP address for the UE; and the target PGW sends a second created session response to the target SGW, wherein the second created session response comprises the uplink endpoint address carried by the second S5/S8 and the second IP address, and the target SGW sends uplink data to the target PGW according to the uplink endpoint address carried by the second S5/S8. In this implementation, the PGW may assign a new IP address to the UE, and the UE may maintain a session connection with the application server using the new IP address.

The fourth aspect provides a PGW handover method for maintaining service continuity, where in a communication system to which the method is applied, a packet data network PDN connection is established between a UE and an application server, the PDN connection includes a first IP address of the UE, an eNB establishes a first S1 bearer for the PDN connection with a source SGW, and the source SGW establishes a first S5/S8 bearer for the PDN connection with the source PGW. The method comprises the following steps: the eNB receives a PDN connection modification request sent by the MME, wherein the PDN connection modification request comprises a second IP address and an uplink endpoint address carried by a second S1, and the eNB configures a downlink endpoint address carried by a second S1 according to the uplink endpoint address carried by a second S1; and the eNB sends the PGW reconfiguration notification comprising the second IP address to the UE, and the UE keeps session connection with the application server according to the second IP address and the connection identifier. After receiving the PGW reconfiguration notification confirmation message sent by the UE, the eNB modifies the S1 bearer in the uplink data channel of the UE from the first S1 bearer to the second S1 bearer according to the uplink endpoint address of the second S1 bearer, and then sends a PDN connection modification response to the MME. The target SGW is different from the source SGW, and the uplink end point and the downlink end point carried by the second S1 are the target SGW and the eNB, respectively. In this way, the eNB switches bearers after the UE updates the IP, thereby establishing a new uplink channel from the UE to the application server.

A fifth aspect provides a PGW handover method for maintaining service continuity, where in a communication system applied in the method, a UE establishes a PDN connection with an application server, the PDN connection includes a first IP address of the UE, an eNB establishes a first S1 bearer with a source SGW for the PDN connection, and the source SGW establishes a first S5/S8 bearer with the source PGW for the PDN connection, and the method includes: the MME determines a target PGW, wherein the target PGW is a PGW redistributed by the MME for PDN connection; the MME sends a PDN connection modification request comprising a bearer identifier of a first S1 bearer to a source SGW, so that the source SGW sends a session creation request to a target PGW, and takes a downlink endpoint address of the first S5/S8 bearer as a downlink endpoint address of a second S5/S8 bearer according to the PDN connection modification request, wherein the session creation request is used for indicating the target PGW to configure an uplink endpoint address of the second S5/S8 bearer and allocate a second IP address to the UE; the MME receives a PDN connection modification response sent by the source SGW, wherein the PDN connection modification response comprises a second IP address; the MME sends a PDN connection modification request comprising a second IP address to the eNB, so that the eNB sends a PGW reconfiguration notification comprising the second IP address to the UE, and the PGW reconfiguration notification is used for indicating the UE to modify the IP address of the PDN connection from the first IP address to the second IP address; and the MME receives a PDN connection modification response sent by the eNB, sends a bearer switching notification to the source SGW according to the PDN connection modification response, and the source SGW switches the first S5/S8 bearer to the second S5/S8 bearer according to the bearer switching notification. According to the implementation, the UE and the application server can keep the original session connection when the PGW is switched, and the problem that the original service connection is interrupted due to the PGW switching in the prior art is solved.

In a possible implementation manner of the fifth aspect, after the MME receives the PDN connection modification response sent by the eNB, the MME sends a PDN connection deletion notification request including a bearer identifier to the source SGW, where the bearer identifier corresponds to the first S1 bearer and the first S5/S8 bearer, so that the source SGW sends a session deletion request including the bearer identifier to the source PGW, and the session deletion request is used to instruct the source PGW to delete the uplink endpoint address of the first S5/S8 bearer and release the first IP address; and the MME receives a PDN connection deletion notification response sent by the source SGW, and generates the PDN connection deletion notification response after the source SGW receives the session deletion response sent by the source PGW. By this implementation, after the PDN connection provided by the source SGW and the source PGW for the UE fails, the source SGW and the source PGW can release the original IP address, thereby saving network resources.

A sixth aspect provides a PGW handover method for maintaining service continuity, where in a communication system applied in the method, a UE establishes a PDN connection with an application server, the PDN connection includes a first IP address of the UE, an eNB establishes a first S1 bearer with a source SGW for the PDN connection, and the source SGW establishes a first S5/S8 bearer with the source PGW for the PDN connection, and the method includes: the UE receives a PGW reconfiguration notification including a second IP address from the eNB, wherein the second IP address is allocated to the UE by a target PGW, and the target PGW is different from the source PGW; the UE generates an IP reconfiguration notification comprising a second IP address and a connection identifier, and sends the IP reconfiguration notification to the application server, so that the application server keeps session connection with the UE according to the second IP address and the connection identifier; the UE sends a PGW reconfiguration notification acknowledgement message to the eNB. By the implementation, after the UE receives the new IP address, the original session connection can be maintained with the application server through the new IP address and the connection identifier.

In a possible implementation manner of the sixth aspect, the UE receives a PGW reconfiguration notification including the second IP address from the eNB through an RRC layer of a control plane protocol stack of the UE; the UE acquires an IP available notification comprising a second IP address from an RRC layer of a control plane protocol stack of the UE through an STP layer of the user plane protocol stack of the UE, and generates an IP reconfiguration notification comprising the second IP address and a connection identifier; and sending the IP reconfiguration notification to an STP layer of an application server through the STP layer of a user plane protocol stack of the UE.

In another possible implementation manner of the sixth aspect, after the UE receives the PGW reconfiguration notification sent by the eNB, the UE deactivates the first IP address.

A seventh aspect provides a PGW handover method for maintaining service continuity, where in a communication system applied in the method, a UE establishes a PDN connection with an application server, the PDN connection includes a first IP address of the UE, an eNB establishes a first S1 bearer with a source SGW for the PDN connection, and the source SGW establishes a first S5/S8 bearer with the source PGW for the PDN connection. The method comprises the following steps: the target PGW receives a session creation request including the downlink endpoint address carried by the second S5/S8 sent by the source SGW, configures the uplink endpoint address carried by the second S5/S8 according to the downlink endpoint address carried by the second S5/S8, allocates a second IP address to the UE, and then sends a session creation response to the source SGW. Wherein the bearer identity of the second S5/S8 bearer is the same as the bearer identity of the first S5/S8 bearer, and the create session response includes the uplink endpoint address and the second IP address of the second S5/S8 bearer. In this implementation, the PGW may assign a new IP address to the UE, and the UE may maintain a session connection with the application server using the new IP address.

An eighth aspect provides a PGW handover method for maintaining service continuity, where in a communication system to which the method is applied, a UE establishes a PDN connection with an application server, the PDN connection includes a first IP address of the UE, an eNB establishes a first S1 bearer with a source SGW for the PDN connection, and the source SGW establishes a first S5/S8 bearer with the source PGW for the PDN connection, and the method includes: the eNB receives a PDN connection modification request sent by the MME, wherein the PDN connection modification request comprises a second IP address; the eNB sends the PGW reconfiguration notification including the second IP address to the UE, so that the UE keeps session connection with the application server according to the second IP address and the connection identifier; and the eNB sends a PDN connection modification response to the MME after receiving the PGW reconfiguration notification confirmation message sent by the UE. In this way, the eNB notifies the MME to send a bearer switching notification to the source SGW after the UE updates the IP, and establishes a new uplink data channel from the UE to the application server after the source SGW completes SGW uplink bearer switching according to the bearer switching notification.

A ninth aspect provides an MME having a function of implementing the MME in the PGW handover method for maintaining service continuity provided in the first aspect or the fifth aspect. The functions can be realized by hardware, and corresponding software can be executed by hardware, and the hardware or the software comprises one or more modules corresponding to the functions.

A tenth aspect provides a UE having a function of implementing the UE in the PGW handover method for maintaining service continuity provided in the second aspect or the sixth aspect. The functions can be realized by hardware, and corresponding software can be executed by hardware, and the hardware or the software comprises one or more modules corresponding to the functions.

An eleventh aspect provides a PGW, where the PGW has a function of implementing a target PGW in the PGW handover method for maintaining service continuity provided in the third aspect or the seventh aspect. The functions can be realized by hardware, and corresponding software can be executed by hardware, and the hardware or the software comprises one or more modules corresponding to the functions.

A twelfth aspect provides an eNB having a function of implementing the eNB in the PGW handover method for maintaining service continuity provided in the fourth aspect or the eighth aspect. The functions can be realized by hardware, and corresponding software can be executed by hardware, and the hardware or the software comprises one or more modules corresponding to the functions.

It can be seen from the embodiment of the present invention that, an MME may configure a target PGW and a target PGW for PDN connection, and through signaling interaction, the target SGW and the target PGW may configure two end addresses of a second S1 bearer and two end addresses of a second S5/S8 bearer, respectively, so as to establish a new bearer between an eNB and the PGW, and then use a radio bearer between the UE and the eNB to establish an EPS bearer between the UE and the target PGW. And the target PGW allocates a second IP address for the UE, the UE notifies the second IP address to the application server after receiving the second IP address, the application server can continue session connection with the UE according to the second IP address, and downlink data of the session is forwarded to the UE through the target PGW and the target SGW. And the eNB modifies the S1 bearer of the uplink data channel of the UE from the first S1 bearer to the second S1 bearer, so that the uplink data from the UE to the application server is forwarded through the target SGW and the target PGW. As can be seen, in the case of switching the data transmission channel of the UE from the source PGW to the target PGW, the UE and the application server may continue the session.

Drawings

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

fig. 2 is a schematic diagram illustrating a packet data network gateway reselection in the prior art;

fig. 3 is a schematic diagram of a bearer of an evolved packet system according to an embodiment of the present invention;

fig. 4 is a flowchart illustrating a PGW handover method for maintaining service continuity according to an embodiment of the present invention;

fig. 5 is a schematic diagram of the correspondence relationship between the TCP protocol, the UDP protocol, and the STP protocol and the IP address respectively in the embodiment of the present invention;

FIG. 6 is a diagram illustrating a message notification mechanism between protocol stacks according to an embodiment of the present invention;

FIG. 7 is a diagram illustrating a method for deleting a session according to an embodiment of the present invention;

fig. 8 is another flowchart of a PGW handover method for maintaining service continuity according to an embodiment of the present invention;

fig. 9 is a schematic diagram of a mobility management entity in an embodiment of the present invention;

fig. 10 is a schematic diagram of a user equipment in an embodiment of the present invention;

FIG. 11 is a diagram of a packet data network gateway in an embodiment of the present invention;

fig. 12 is a schematic diagram of an enb in an embodiment of the present invention;

fig. 13 is another diagram of a mobility management entity in an embodiment of the present invention;

fig. 14 is another schematic diagram of a user equipment in an embodiment of the present invention;

fig. 15 is another schematic diagram of a packet data network gateway in an embodiment of the present invention;

fig. 16 is another schematic diagram of an enb in an embodiment of the present invention;

fig. 17 is another diagram of a mobility management entity in an embodiment of the present invention;

fig. 18 is another schematic diagram of a user equipment in an embodiment of the present invention;

fig. 19 is another diagram of a packet data network gateway in an embodiment of the present invention;

fig. 20 is another schematic diagram of an enb in an embodiment of the present invention.

Detailed Description

The invention provides a PGW switching method for maintaining service continuity, which can be applied to a communication system. The communication system shown in fig. 2 includes a Mobility Management Entity (MME), a Serving Gateway (SGW), a packet data network gateway (PGW), a Home Subscriber Server (HSS), an evolved node B (eNB), an Application Server (Application Server), and a User Equipment (UE). Among them, SGW is also called S-GW. The PGW is also called PDN GW. The MME, the SGW, the PGW, and the HSS belong to a Core network device, and the Core network may be an Evolved Packet Core (EPC for short). The eNB belongs to an access network device.

The MME is responsible for managing and storing UE contexts (such as UE identity/user identity, mobility management status, user security parameters, etc.), assigning temporary identities to users, and authenticating the users when the UE is camped in the tracking area or the network.

The PGW is a border gateway of the EPC, and provides functions of session management and bearer control, data forwarding, IP address allocation, non-3 GPP user access, and the like of a user. It is the anchor point of 3GPP access and non-3 GPP access public data network (PDN for short).

The eNB is a bridge between the UE and the EPC, and is used for radio resource management, MME selection when the UE attaches, routing a user data plane to an SGW or measurement configuration, and the like.

The UE, also referred to as a terminal, is capable of communicating over a wireless communication network. Such as a mobile phone, a tablet computer, a vehicle-mounted computer, a wearable electronic device, or a Personal Digital Assistant (PDA).

For ease of understanding, a service architecture carried by an Evolved Packet System (EPS) will be described first. Referring to fig. 3, in the service architecture of ESP bearer, the end-to-end service can be decomposed into an EPS bearer and an external bearer. Wherein the EPS bearer can be decomposed into a radio bearer, an S1 bearer, and an S5/S8 bearer. When the terminal is connected to a PDN, the EPS system establishes an EPS bearer for the PDN connection. The EPS bearer will be reserved throughout the PDN connection, i.e. the terminal is provided with a continuous IP connection to the PDN, this bearer being the default bearer.

In order to maintain the continuity of the service, the invention provides a PGW switching method for maintaining the continuity of the service. Referring to fig. 4, an embodiment of a PGW handover method for maintaining service continuity according to the present invention includes:

step 401, the MME determines the target PGW and the target SGW.

In this embodiment, in the process of establishing a session between the UE and the application server, the UE and the application server need to establish a PDN connection first, and the EPS establishes a first EPS bearer for the PDN connection. The first EPS bearer comprises a first S1 bearer, a first S5/S8 bearer and a radio bearer, the eNB is a downlink endpoint of the first S1 bearer, the source SGW is an uplink endpoint of the first S1 bearer and a downlink endpoint of the first S5/S8 bearer, and the source PGW is an uplink endpoint of the first S5/S8 bearer. The EPS establishes an external bearer between the source PGW and the application server for the PDN connection, and forms a session channel from the UE to the application server.

The target PGW refers to one PGW other than the source PGW in the EPC. The MME may select a target PGW from the candidate PGWs according to one or more of service statistics information, network topology, load balancing, internal events, or Access Point Names (APNs). The target SGW refers to one SGW in the EPC other than the source SGW. The MME selects a target SGW from the candidate SGWs based on one or more of network topology, load balancing, or internal events. The specific process of the MME selecting the target PGW from the candidate PGWs may be referred to the following embodiments.

In an optional embodiment, the MME determines the target PGW according to the traffic statistics information. Specifically, the terminal acquires service statistical information, reports the service statistical information to the MME, and the MME determines the target PGW according to the service statistical information. For example, the service statistical information is a Content Delivery Network (CDN) and a service data amount received by the UE from the CDN, and when the data amount received by the UE from the target CDN exceeds a preset data amount, if a distance between the candidate PGW and the target CDN is smaller than a distance between the source PGW and the target CDN, the candidate PGW is determined to be the target PGW. Therefore, a large amount of service data reaches the target CDN through the PGW with a shorter distance, the data transmission distance can be shortened, and the transmission efficiency of the service data is improved. For another example, if the packet drop rate between the candidate PGW and the target CDN is smaller than the packet drop rate between the source PGW and the target CDN, the candidate PGW is determined to be the target PGW. By this implementation, the MME may select the PGW with a better network status for data transmission, thereby improving the data transmission quality.

In another optional embodiment, the MME determines the target PGW according to the network topology. Specifically, the UE reports the geographical location of the UE to the MME, the MME queries a service area of which PGW the geographical location of the UE belongs to, and selects one PGW capable of providing a service for the UE as a target PGW. By this implementation, the UE can be guaranteed to be within the service area of the target PGW.

In another optional embodiment, the MME determines the target PGW based on an internal event. The internal event refers to an event other than a mobility event such as location area update and handover, such as Selective IP traffic offload (SIPTO) establishment.

In another optional embodiment, the MME determines the target PGW based on load balancing. Specifically, the MME acquires a PGW weight factor of the candidate PGW from a Domain Name System (DNS) server, and configures a traffic load threshold of each PGW for a configuration duration according to the PGW weight factor. And when the traffic load threshold of the candidate PGW in the configured time length is smaller than a preset threshold, determining the candidate PGW as the target PGW. Wherein the PGW weight factor may be determined according to a load capacity of the PGW. And in this way, the service flow is borne according to the load capacity of the PGW, so that the network load balance is realized.

In another optional embodiment, the MME determines the target PGW according to the APN. Specifically, the MME selects the target PGW according to the APN address mapping. PDN networks are differentiated in packet data networks using APNs. The APN may be CMNET, CMWAP, or the like. For example, when an APN is CMNET, its corresponding PDN provides an Internet (Internet) access service. When the APN is a CMWAP, its corresponding PDN provides a Wireless Application Protocol (WAP) web service.

Step 402, the MME sends a first Create Session Request (Create Session Request) to the target SGW.

Specifically, the MME initiates a procedure of configuring a second S1 bearer and a second S5/S8 bearer for the PDN connection, where the first create session request includes a downlink endpoint address of the first S1 bearer, and the eNB is a downlink endpoint of the first S1 bearer and is also a downlink endpoint of the second S1 bearer. The first create session request further includes an identity of the User, such as an International Mobile Subscriber Identity (IMSI), User Location Information (User Location Information), and the like, as well as access network Information, server network Information, control plane tunnel Information, Information of S5/S8 interface (such as protocol type, PDN address), PDN type, and Information related to a default EPS bearer (such as an EPS bearer identity, Quality of Service (QoS)).

And step 403, the target SGW configures the uplink endpoint carried by the second S1 and the downlink endpoint carried by the second S5/S8 according to the first create session request. Specifically, based on that the downlink endpoint address of the first S1 bearer included in the first create session request corresponds to the eNB, it may be determined that the destination node of the downlink session data sent from the target SGW is the eNB for the session data between the UE and the application server. When receiving the first create session request, the target SGW configures the uplink endpoint address of the second S1 bearer, i.e. the target SGW is used as the uplink endpoint of the second S1 bearer, thereby creating a second S1 bearer between the target SGW and the eNB. And configuring the downstream endpoint address carried by the second S5/S8, i.e. the target SGW as the downstream endpoint carried by the second S5/S8.

Step 404, the target SGW sends a second create session request to the target PGW. It will be appreciated that the second session request includes other information of the first session request (such as user identity, user location information and access network information, server network information, control plane tunnel information, information of the S5/S8 interface, PDN type and information related to the default EPS bearer, etc.) in addition to not including the downstream endpoint address of the first S1 bearer.

Step 405, the target PGW configures the uplink endpoint address carried by the second S5/S8 according to the second create session request, and allocates a second IP address to the UE.

Step 406, the target PGW sends a second Create session response message (Create session response) to the target SGW. The second create session response message includes the upstream endpoint address and the second IP address carried by the second S5/S8.

Step 407, the target SGW sends a first create session response to the MME. The first session response includes the downstream endpoint address and the second IP address carried by the second S5/S8.

Specifically, after receiving the second create session response message from the target PGW, the target SGW may establish the second S5/S8 bearer between the target SGW and the target PGW by using the configured downlink endpoint address of the second S5/S8 according to the uplink endpoint address of the second S5/S8 bearer, and then the target SGW sends the first create session response to the MME. For the session data between the UE and the application server, the target SGW may determine that a destination node of the uplink session data is the target PGW. At this time, the configuration of the uplink and downlink endpoints of the second S1 bearer and the second S5/S8 bearer is completed, the MME establishes a second S1 bearer and a second S5/S8 bearer for the PDN connection, and the second S1 bearer and the second S5/S8 bearer refer to bearers of the user plane and are mainly responsible for transmitting service data.

In step 408, the MME sends a PDN connection modification Request (i.e. Bearer Modify Request) to the eNB, where the PDN connection modification Request includes the uplink endpoint address and the second IP address carried by the second S1. Based on the uplink endpoint address carried by the second S1 corresponding to the target SGW, the eNB may determine that the target SGW may serve as a destination node for the uplink session data.

In step 409, the eNB sends a PGW reconfiguration notification (i.e., PGW replacement notification) to the UE. The PGW reconfiguration notification includes the second IP address, and may further include a Data Radio Bearer (DRB) identifier. The data radio bearer identifier is used for identifying a radio bearer between the UE and the eNB for data transmission in a user plane. It should be noted that the EPS bearer identifier included in the first session request and the second session request is a bearer identifier of the first EPS bearer and is also a bearer identifier of the second EPS bearer. The first EPS bearer comprises a radio bearer, a first S1 bearer and a first S5/S8 bearer, the radio bearer from the UE to the eNB in the second EPS bearer can be determined by using the EPS bearer identification, and the second EPS bearer from the UE to the target PGW is formed by establishing the second S1 bearer, the second S5/S8 bearer and the radio bearer.

Step 410, the UE generates an IP reconfiguration notification (i.e., iprallconfiguration notification) including the second IP address and the connection identity.

Specifically, after receiving the PGW reconfiguration notification, the UE constructs an IP reconfiguration notification according to the second IP address and the CID, where the IP reconfiguration notification may further include authentication information of the user session, and the like. The CID is used to identify session connection of the application layer, and the authentication information of the user session is used for the application server to perform authentication on the UE.

Step 411, the UE sends an IP reconfiguration notification to the application server.

Step 412, the application server sends an IP reconfiguration notification acknowledgement message (i.e. IP reconfiguration notification Ack) to the UE through the target PGW and the target SGW.

Because the first EPS bearer is established from the UE to the source PGW, the UE sends the IP reconfiguration notification to the application server through the source SGW and the source PGW. Wherein, both the UE and the application server configure a flexible Transport Protocol (STP) Protocol. The application server knows the second IP address and the CID included in the IP reconfiguration notification according to the second IP address, the second IP address and the IP address connected with the original session correspond to the same session, and the application server sends an IP reconfiguration notification confirmation message to the UE corresponding to the second IP address, which indicates that a downlink data channel of the application server → the target PGW → the target SGW → the UE is established, and the downlink data channel is a session path for transmitting downlink data. Next, the application server may send session data to the UE through the downlink data channel. As can be seen, the application server may continue the original session connection based on the second IP address and the CID. The STP protocol realizes separation of a transport layer and an IP layer, and a client under the same STP connection can have a plurality of IP addresses (such as IP1 or IP 2); the TCP or UDP transport protocol requires one-to-one binding with the IP address, and the correspondence between TCP, UDP, and STP and the IP address is shown in fig. 5.

It should be noted that, in the case that the UE establishes session connections with multiple application servers, if all session connections are to be maintained, in an optional embodiment, after receiving the IP reconfiguration notification acknowledgement messages sent by all application servers, the UE performs step 413.

In step 413, the UE sends a PGW reconfiguration notification acknowledgement message (i.e., PGW Reallocation notify ack) to the eNB.

As shown in steps 412 and 413, after receiving the IP reallocation notification confirmation message, the UE determines that the second S1 bearer and the second S5/S8 bearer are established, and sends a PGW reconfiguration notification confirmation message to the eNB.

In an optional embodiment, when receiving the PGW reconfiguration notification, the UE starts a timer for sending a PGW reconfiguration notification acknowledgment message, and when the timer is expired or the timer is set to 0, the UE sends the PGW reconfiguration notification acknowledgment message to the eNB. In this embodiment, the application server may not feed back the IP reallocation notification confirmation message to the UE, and the UE may send the PGW reconfiguration notification to the eNB, and then perform step 414.

In step 414, after receiving the PGW reconfiguration notification confirmation message, the eNB switches the S1 bearer of the uplink data channel from the first S1 bearer to the second S1 bearer.

Specifically, after receiving the PGW reconfiguration notification confirmation message, the eNB determines that a new session path is established, and switches the S1 bearer of the uplink data channel from the first S1 bearer to the second S1 bearer, where the uplink data channel of the original user plane fails. After the handover is completed, step 415 is performed.

Step 415, the eNB sends a PDN connection modification Response (i.e. Bearer modification Response) to the MME, and notifies the MME that the uplink data channel of the original user plane is invalid.

In this embodiment, in the process of switching from the source PGW to the target PGW, the target PGW allocates a new IP address (i.e., a second IP address) to the UE, then establishes a new EPS bearer (i.e., a second EPS bearer) for the PDN connection between the UE and the application server, switches to the second EPS bearer through the first EPS bearer, establishes a new session channel from the UE to the application server, and the UE and the application server may continue the original service through the new session channel.

Based on the embodiment shown in fig. 4, the following describes the inter-protocol stack message notification mechanism between the UE and the application server. Referring to fig. 6, in the ue configuration Protocol, a Control plane Protocol of the ue includes a Non-Access stratum (NAS), a Radio Resource Control (RRC), a Packet Data Convergence Protocol (PDCP), a Radio Link Control (RLC), a Medium Access Control (MAC), and a Physical Layer (PHY), and the user plane Protocol of the ue includes the PDCP, the RLC, the MAC, and the PHY, and further includes an application Layer (APP Layer), an STP Layer, a proxy Layer (also referred to as Prox Layer), and an IP Layer. In the application server configuration protocol, the user plane protocol layers of the application server include an APP Layer, an STP Layer, an IP Layer, and a Layer 1(Layer1, abbreviated as L1)/a Layer 2(Layer2, abbreviated as L2).

Step 601, after the eNB sends the PGW reconfiguration notification to the UE, the UE receives the PGW reconfiguration notification through the RRC layer, acquires the second IP address, generates an IP availability notification (i.e., IP Available notification) in the RRC layer, sends the IP availability notification from the RRC layer, transfers the notification through the NAS layer, transfers the notification through the Prox layer, and then reaches the STP layer.

Step 602, the UE processes the IP available notification by using the STP protocol, generates an IP reconfiguration notification including the second IP address and the connection identifier, and then the STP layer of the UE sends the IP reconfiguration notification to all application servers currently in the connected state. The IP reconfiguration notification includes information such as the second IP address and the CID identifier, and is received and processed by the STP layer of the application server.

Step 603, the STP layer of the application server sends an IP reconfiguration notification acknowledgement message to the STP layer of the UE.

Step 604, the IP available notification acknowledgement message is sent from the STP layer of the UE, relayed through the Prox layer, and relayed through the NAS layer to reach the RRC layer of the UE.

After step 412 and before step 415, the UE may receive two types of downlink data messages including the IP address of the original session connection and the second IP address, and the present invention may deactivate the IP address of the original session connection through the cooperation of the STP protocol and the LTE protocol to solve the multiple IP address problem. In particular, reference may be made to the following: and when the IP reconfiguration notification confirmation message is received, the UE deactivates the IP address of the original session connection. Or, when the UE sends the IP reconfiguration notification to the application server, starting a timer; and when the timer is returned to 0 or the timer is overtime, the UE deactivates the IP address of the original session connection. Or, after the UE sends the PGW reconfiguration notification acknowledgement message to the eNB, the UE deactivates the IP address of the original session connection.

After the uplink and downlink channels between the UE and the application server are established, after the S1 bearer of the uplink channel of the UE is switched from the first S1 bearer to the second S1 bearer, the original session path is invalid. The method provided by the present invention can release the first S1 bearer, and save network resources, please refer to the following embodiments. Referring to fig. 7, based on the embodiment shown in fig. 4, another embodiment of the PGW switching method for maintaining service continuity provided by the present invention includes:

step 701, the MME sends a first delete session request to the source SGW. The first delete session request includes a bearer identification corresponding to the first S1 bearer and the first S5/S8 bearer.

In an optional embodiment, the MME starts a timer when receiving the first create session response; if the timer is back to 0 or the timer times out, the MME sends a first delete session request to the source SGW. Specifically, when the MME receives the first create session response, it determines that the second S1 bearer and the second S5/S8 bearer are established, and the new session path is established, and may delete the original session path.

In another optional embodiment, when the MME receives the PDN connectivity modification response sent by the eNB, the MME sends a delete session request to the source SGW.

Step 702, the source SGW sends a second delete session request to the source PGW. The second delete session request includes the bearer identification. And the source PGW deletes the uplink endpoint borne by the first S5/S8 according to the bearing identifier, and releases the first IP address, for example, the first IP address is stored in the IP resource pool to be used as the IP address to be allocated.

And step 703, the source PGW sends a second delete session response to the source SGW after deleting the uplink endpoint carried by the first S5/S8.

Step 704, the source SGW sends a first delete session response to the MME.

In this embodiment, after the source PGW deletes the uplink endpoint carried by the first S5/S8, the downlink user plane data channel connected to the original session is invalid.

The EPS bearer established by the target PGW and the target SGW is described above, and the EPS bearer established by the target PGW and the source SGW is described below. Referring to fig. 8, another embodiment of the PGW handover method for maintaining service continuity according to the present invention includes:

step 801, the MME determines the target PGW. The target PGW is a PGW that the MME reallocates for the PDN connection.

In this embodiment, the process of determining the target PGW by the MME is similar to that of determining the target PGW by the MME in step 401, and details are not repeated here.

Step 802, the MME sends a PDN connection modification request to the source SGW. The modified PDN connection request includes a bearer identification identifying the first S1 bearer and the second S5/S8 bearer, and the source SGW may determine an uplink endpoint and a downlink endpoint of the first S1 bearer according to the bearer identification.

And step 803, the source SGW takes the downlink endpoint address carried in the first S5/S8 as the downlink endpoint carried in the second S5/S8 according to the bearer identifier of the PDN connection modification request.

And step 804, the source SGW sends a session creation request to the target PGW. The create session request includes the downstream endpoint address carried by the second S5/S8.

Step 805, the target PGW configures the uplink endpoint address carried by the second S5/S8 according to the create session request, and allocates a second IP address to the UE.

Step 806, the target PGW sends a create session response to the source SGW, where the create session response includes the uplink endpoint address and the second IP address carried by the second S5/S8. And the source SGW determines that the target PGW is available according to the uplink endpoint address carried by the second S5/S8.

Step 807, the source SGW sends a modify PDN connection response to the MME. The modified PDN connectivity response may include the second IP address and may also include a downstream endpoint address carried by the second S5/S8.

From step 802 to step 807, after configuring the uplink endpoint and the downlink endpoint of the second S5/S8 bearer respectively by the source SGW and the target PGW according to the bearer identifier, the first S1 bearer and the second S5/S8 bearer from the eNB to the PGW are established.

Step 808, the MME sends a PDN connection modification request to the eNB, the PDN connection modification request including the second IP address. It is to be understood that the PDN connection modification request further includes an uplink endpoint address carried by the first S1. The eNB may send uplink data to the source SGW according to the uplink endpoint address carried by the first S1.

Step 809, the eNB sends a PGW reconfiguration notification to the UE. The PGW reconfiguration notification includes the second IP address and may also include a radio bearer identification. The eNB may determine a radio bearer from the eNB to the UE from the first S1 bearer.

Step 810, the UE generates an IP reconfiguration notification including the second IP address and the connection identifier, and the IP reconfiguration notification may further include authentication information of the user session.

Step 811, the UE sends an IP reconfiguration notification to the application server. IP reconfiguration notification is by UE → source SGW → source PGW → application server. The procedure for the application server to maintain a session connection with the application server according to the IP reconfiguration notification is similar to step 411.

Step 812, the application server sends an IP reconfiguration notification acknowledgement message to the UE.

Wherein, the UE and the application server are both configured with STP protocol. The application server knows the second IP address and the CID included in the IP reconfiguration notification according to the CID, the second IP address and the IP address connected with the original session correspond to the same session, and the application server sends an IP reconfiguration notification confirmation message to the UE corresponding to the second IP address, which indicates that a downlink data channel of the application server → the target PGW → the source SGW → the UE is established.

Step 813, the UE sends a PGW reconfiguration notification acknowledgement message to the eNB.

And 814, the eNB sends a PDN connection modification response to the MME after receiving the PGW reconfiguration notification acknowledgement message.

Step 815, the MME sends a bearer handover notification to the source SGW.

And step 816, the source SGW switches the first S5/S8 bearer to the second S5/S8 bearer according to the bearer switching notification. At this time, the source SGW forwards the uplink data from the UE to the target PGW instead of the source PGW. Namely, the session data is forwarded through the target PGW and the source SGW, and the original session path is failed.

In this embodiment, the EPS system allocates a new EPS bearer (i.e., a second EPS bearer) for the PDN connection, where the new EPS bearer includes a radio bearer, a first S1 bearer from the eNB to the source SGW, and a second S5/S8 bearer from the source SGW to the source PGW. And switching to a second EPS bearer through the first EPS bearer, establishing a new session channel from the UE to the application server, and continuing the original service through the new session channel by the UE and the application server.

Based on the embodiment shown in fig. 8, the present invention may further provide a method for deleting a session, so as to release S1 bearer and save network resources. After step 807, in another alternative embodiment of the present invention, the method may further include:

and the MME sends a PDN connection deletion notification request to the source SGW. The delete PDN connectivity notification request includes a bearer identification corresponding to the first S1 bearer and the first S5/S8 bearer.

In this embodiment, when the MME receives the PDN connectivity modification response, it determines that the first S1 bearer and the second S5/S8 bearer are established, and that a new session path is established, and may delete the original session path. The MME starts a timer; if the timer is set to 0 or the timer times out, the MME sends a delete PDN connection notification request to the source SGW. Or, when the MME receives the PDN connection modification response sent by the eNB, the MME sends a PDN connection deletion notification request to the source SGW.

And the source SGW sends a session deletion request to the source PGW, wherein the session deletion request comprises the bearer identifier. And the source PGW deletes the uplink endpoint address borne by the first S5/S8 according to the bearing identifier, and releases the first IP address, for example, the first IP address is stored in the IP resource pool to be used as the IP address to be allocated.

And the source PGW sends a session deletion response to the source SGW, and the source SGW sends a PDN connection deletion notification response to the MME. When the source PGW deletes the uplink endpoint carried by the first S5/S8, the downlink user plane data channel of the original session connection is disabled.

For convenience of understanding, the following describes in detail a PGW handover method for maintaining service continuity according to an embodiment of the present invention in a specific application scenario:

under the condition that the UE and an Internet Web server forward data through the SGW1 and the PGW1, when the traffic loads of the PGW1 and the SGW1 exceed a preset threshold value, the MME selects the PGW2 and the SGW2 from available PGWs according to a load balancing strategy, and then acquires PDN connection information according to an attachment request of the UE. The IP address of the UE included in the PDN connectivity information is exemplified by IP 1.

The MME sends a modify PDN connection request to the SGW2, the SGW2 creates an uplink endpoint address of the second S1 bearer and a downlink endpoint address of the second S5/S8 bearer, the SGW2 sends a create session request to the PGW2, the PGW2 allocates a new IP address, such as IP2, to the UE, and the PGW2 configures the uplink endpoint address of the second S5/S8 bearer, and then feeds back a create session response to the SGW 2. The SGW2 sets the uplink endpoint of the second S1 bearer as SGW2, and then feeds back the created session response to the MME, thereby establishing a second S5/S8 bearer and a second S1 bearer. At this time, the Web server does not know that the MME configures the PGW2 and the SGW2 for the UE, and therefore the UE and the Web server cannot communicate through the SGW2 and the PGW 2.

The MME sends a PDN connection modification request to the eNB, the IP2 is sent to the UE through the eNB, the UE sends an IP reallocation notice to the Web server through the SGW1 and the PGW1, the IP reallocation notice comprises a CID and an IP2, and the Web server continues session connection with the UE according to the IP2 and the CID. At this time, the Web server may transmit downlink data to the UE according to the IP 2.

The Web server may also send an IP reallocation notification confirmation message to the UE, indicating that the UE and the Web server may communicate through the SGW2 and the PGW 2. And after receiving the IP reallocation notification confirmation message, the UE sends a PGW reconfiguration notification confirmation message to the eNB, instructs the eNB to switch the S1 bearer of the uplink data channel from the first S1 bearer to the second S1 bearer, and then sends a PDN connection modification response to the MME to complete the switching from the PGW1 to the PGW 2. At this time, uplink data sent by the UE to the Web server are all sent to the Web server through the SGW2 and the PGW2, and do not pass through the SGW1 and the PGW1 any more. The MME sends a request for deleting the session to the SGW1 and the PGW1, and the SGW1 and the PGW1 can release the first S1 bearer and the first S5/S8 bearer, so that waste of network resources is avoided.

Under the condition that the UE and an Internet Web server forward data through the SGW1 and the PGW1, when the traffic load of the PGW1 exceeds a preset threshold, the MME selects the PGW2 from available PGWs according to a load balancing strategy, and then acquires PDN connection information according to an attachment request of the UE. The IP address of the UE included in the PDN connectivity information is exemplified by IP 1.

The MME sends a modified PDN connection request including a bearer identity to the SGW1, the SGW1 creates a downlink endpoint address of the second S5/S8 bearer, and the SGW1 may determine, according to the bearer identity, that the first S1 bearer and the second S5/S8 belong to the same EPS bearer. The SGW1 then sends a create session request to the PGW2, the PGW2 allocates a new IP address, such as IP2, to the UE, and the PGW2 configures a downlink endpoint address carried by the second S5/S8, and then feeds back a create session response to the SGW 1. The SGW1 configures the uplink endpoint address of the second S1 bearer, and then feeds back the created session response to the MME, thereby establishing the bearer from the eNB to the PGW 2. At this time, the Web server does not know that the MME configures the PGW2 and the SGW1 for the UE, and therefore the UE and the Web server cannot communicate through the SGW1 and the PGW 2.

The Web server may also send an IP reallocation notification confirmation message to the UE, indicating that the UE and the Web server may communicate through the SGW1 and the PGW 2. And after receiving the IP reallocation notification confirmation message, the UE sends a PGW reconfiguration notification confirmation message to the eNB, then the eNB sends a PDN connection modification response to the MME, the MME sends a bearer switching notification to the SGW1, and the SGW1 switches the first S5/S8 bearer to the second S5/S8 bearer according to the bearer switching notification. At this time, uplink data sent by the UE to the Web server are all sent to the Web server through the SGW1 and the PGW2, and do not pass through the PGW1 any more. The MME sends a PDN connection deleting request to the SGW1, the SGW1 sends a session deleting request to the PGW1 according to the PDN connection deleting request, and the PGW1 can release the first S5/S8 load according to the session deleting request, so that waste of network resources is avoided.

Based on the PGW handover method for maintaining service continuity provided above, a communication device capable of implementing the above method is described below. Referring to fig. 9, the present invention provides an MME900 capable of implementing the functions of the MME in the embodiments shown in fig. 4 to 7. The MME900 includes:

a determining module 901, configured to determine a target PGW and a target SGW, where the target PGW is a PGW reallocated by an MME for PDN connection, and the target SGW is an SGW reallocated by the MME for PDN connection;

a sending module 902, configured to send a first create session request including a downstream endpoint address of the first S1 bearer to the target SGW, so that the target SGW sends a second create session request to the target PGW, where the first create session request is used to instruct the target SGW to configure an upstream endpoint address of the second S1 bearer and a downstream endpoint address of the second S5/S8 bearer, the second create session request is used to instruct the target PGW to configure an upstream endpoint address of the second S5/S8 bearer and allocate a second IP address to the UE, and bearer identifications of the second S1 bearer and the first S1 bearer are the same;

a receiving module 903, configured to receive a first create session response sent by the target SGW, where the first create session response includes an uplink endpoint address and a second IP address that are carried by the second S1;

a sending module 902, further configured to send a PDN connection modification request including an uplink endpoint address and a second IP address of the second S1 bearer to the eNB, so that the eNB sends the second IP address to the UE, and the uplink endpoint address of the second S1 bearer is used for the eNB to modify the S1 bearer of the uplink data channel from the first S1 bearer to the second S1 bearer;

a receiving module 903, configured to receive a PDN connection modification response sent by the eNB.

In an optional embodiment, the sending module 902 is further configured to, after the receiving module receives the PDN connection modification response sent by the eNB, send a first delete session request including a bearer identifier to the source SGW, where the bearer identifier corresponds to the first S1 bearer and the first S5/S8 bearer, so that the source SGW sends a second delete session request including the bearer identifier to the source PGW, where the second delete session request is used to instruct the source PGW to delete an uplink endpoint address of the first S5/S8 bearer and release the first IP address;

the receiving module 903 is further configured to receive a first delete session response sent by the source SGW, where the first delete session response is generated after the source SGW receives a second delete session response sent by the source PGW.

In another optional embodiment, the determining module 901 is specifically configured to select a target PGW from the candidate PGWs according to at least one of service statistics information, network topology, load balancing, internal events, or access point names; and/or selecting a target SGW from the candidate SGWs based on at least one of network topology, load balancing, or internal events.

Referring to fig. 10, the present invention provides a UE1000 capable of implementing the functions of the UE in the embodiments shown in fig. 4 to 7. The UE1000 includes:

a receiving module 1001, configured to receive a PGW reconfiguration notification including a second IP address from an eNB, where the second IP address is allocated by a target PGW for a UE, and the target PGW is different from a source PGW;

a generating module 1002, configured to generate an IP reconfiguration notification including the second IP address and the connection identifier;

a sending module 1003, configured to send the IP reconfiguration notification to the application server, so that the application server maintains session connection with the UE according to the second IP address and the connection identifier;

the sending module 1003 is further configured to send a PGW reconfiguration notification confirmation message to the eNB.

In an optional embodiment, the receiving module 1001 is specifically configured to receive, from the eNB through an RRC layer of a control plane protocol stack of the UE, a PGW reconfiguration notification including the second IP address;

the generating module 1002 is specifically configured to obtain, through an STP layer of a user plane protocol stack of the UE, an IP available notification including the second IP address from an RRC layer of a control plane protocol stack of the UE, and generate an IP reconfiguration notification including the second IP address and the connection identifier;

the sending module 1003 is specifically configured to send the IP reconfiguration notification to an STP layer of the application server through an STP layer of a user plane protocol stack of the UE.

In an optional embodiment, the UE1000 further comprises:

a deactivation module, configured to deactivate the first IP address after the receiving module 1001 receives the PGW reconfiguration notification sent by the eNB.

In another optional embodiment, the sending module 1003 is specifically configured to start a timer when the receiving module 1001 receives the PGW reconfiguration notification sent by the eNB; and when the timing duration of the timer is not less than the preset duration, sending a PGW reconfiguration notification confirmation message to the eNB.

In another optional embodiment, the sending module 1003 is specifically configured to send a PGW reconfiguration notification confirmation message to the eNB when the receiving module 1001 receives the IP reconfiguration notification confirmation message sent by the application server.

Referring to fig. 11, the present invention provides a PGW1100 capable of implementing the functions of the target PGW in the embodiments shown in fig. 4 to 7. PGW1100 comprises:

a receiving module 1101, configured to receive a second create session request sent by a target SGW, where the second create session request includes a downlink endpoint address carried in a second S5/S8, and the target SGW is different from the source SGW;

a processing module 1102, configured to configure an uplink endpoint address carried by the second S5/S8 according to the second create session request, and allocate a second IP address to the UE;

a sending module 1103, configured to send a second create session response to the target SGW, where the second create session response includes the upstream endpoint address and the second IP address carried in the second S5/S8.

The invention provides an SGW which can realize the functions of the SGW in the embodiment shown in FIG. 4 or FIG. 8. The SGW includes:

a receiving module, configured to receive a first create session request sent by an MME and including a downlink endpoint address carried by a first S1;

a processing module, configured to configure an uplink endpoint address of a first S1 bearer and a downlink endpoint address of a second S5/S8 bearer according to the first create session request;

a sending module, configured to send a second session creation request to the target PGW;

the receiving module is further configured to receive a second session creation response sent by the target PGW;

the sending module is further configured to send a first create session response to the MME.

Referring to fig. 12, the present invention provides an eNB1200, which can implement the functions of the eNB in the embodiments shown in fig. 4 to 7. The eNB1200 includes:

a receiving module 1201, configured to receive a PDN connection modification request sent by the MME, where the PDN connection modification request includes a second IP address and an uplink endpoint address carried by a second S1, and the target SGW is different from the source SGW;

a sending module 1202, configured to send a PGW reconfiguration notification including the second IP address to the UE, so that the UE maintains session connection with the application server according to the second IP address and the connection identifier;

a receiving module 1201, further configured to receive a PGW reconfiguration notification acknowledgement message sent by the UE;

a modifying module 1203, configured to modify, according to the uplink endpoint address of the second S1 bearer, the S1 bearer in the uplink data channel of the UE from the first S1 bearer to a second S1 bearer, where an uplink endpoint and a downlink endpoint of the second S1 bearer are a target SGW and an eNB, respectively;

a sending module 1202 is further configured to send a PDN connection modification response to the MME.

Referring to fig. 13, the present invention provides an MME1300 capable of implementing the function of the MME in the embodiment shown in fig. 8. The MME1300 includes:

a determining module 1301, configured to determine a target PGW, where the target PGW is a PGW reallocated by an MME for a PDN connection;

a sending module 1302, configured to send a PDN connection modification request including a bearer identifier of the first S1 bearer to the source SGW, so that the source SGW sends a create session request to the target PGW, where the PDN connection modification request is used to instruct the source SGW to use a downlink endpoint address of the first S5/S8 bearer as a downlink endpoint address of the second S5/S8 bearer, and the create session request is used to instruct the target PGW to configure an uplink endpoint address of the second S5/S8 bearer and allocate a second IP address to the UE;

a receiving module 1303, configured to receive a PDN modification connection response sent by the source SGW, where the PDN modification response includes an uplink endpoint address and a second IP address that are carried by the second S1;

a sending module 1302, configured to send a PDN connection modification request including a second IP address to the eNB, so that the eNB sends a PGW reconfiguration notification including the second IP address to the UE, where the PGW reconfiguration notification is used to instruct the UE to modify an IP address of the PDN connection from the first IP address to the second IP address;

a receiving module 1303, configured to receive a PDN connection modification response sent by the eNB;

the sending module 1302 is further configured to send a bearer switching notification to the source SGW according to the PDN connection modification response, where the bearer switching notification is used to instruct the source SGW to switch the first S5/S8 bearer to the second S5/S8 bearer.

In an alternative embodiment of the method of the invention,

a sending module 1302, configured to send a PDN connection deletion notification request including a bearer identifier to the source SGW after the MME receives the PDN connection modification response sent by the eNB, so that the source SGW sends a session deletion request including the bearer identifier to the source PGW;

the receiving module 1303 is further configured to receive a PDN connection deletion notification response sent by the source SGW, where the PDN connection deletion notification response is generated after the source SGW receives the session deletion response sent by the source PGW.

Referring to fig. 14, the present invention provides a UE1400, which can implement the function of the UE in the PGW handover method for maintaining service continuity. The UE1400 includes:

a receiving module 1401, configured to receive, from the eNB, a PGW reconfiguration notification including a second IP address, where the second IP address is allocated by a target PGW for the UE, and the target PGW is different from the source PGW;

a generating module 1402, configured to generate an IP reconfiguration notification including the second IP address and the connection identifier;

a sending module 1403, configured to send the IP reconfiguration notification to the application server, so that the application server maintains session connection with the UE according to the second IP address and the connection identifier;

a sending module 1403, further configured to send a PGW reconfiguration notification acknowledgement message to the eNB.

In an optional embodiment, the receiving module 1401 is specifically configured to receive, from the eNB through an RRC layer of a control plane protocol stack of the UE, a PGW reconfiguration notification including the second IP address;

the generating module 1402 is specifically configured to obtain, through an STP layer of a user plane protocol stack of the UE, an IP available notification including the second IP address from an RRC layer of a control plane protocol stack of the UE, and generate an IP reconfiguration notification including the second IP address and the connection identifier;

the sending module 1403 is specifically configured to send the IP reconfiguration notification to the STP layer of the application server through the STP layer of the user plane protocol stack of the UE.

In another optional embodiment, the UE1400 further comprises:

a deactivation module, configured to deactivate the first IP address after the receiving module 1401 receives the PGW reconfiguration notification sent by the eNB.

Referring to fig. 15, the present invention provides a PGW1500, which can implement the function of a source PGW in the PGW switching method for maintaining service continuity in the embodiment shown in fig. 8. PGW1500 includes:

a receiving module 1501, configured to receive a session creation request that is sent by a source SGW and includes a downlink endpoint address of a second S5/S8 bearer, where a bearer identifier of the second S5/S8 bearer is the same as a bearer identifier of the first S5/S8 bearer;

a processing module 1502, configured to configure an uplink endpoint address carried in the second S5/S8 according to the downlink endpoint address carried in the second S5/S8, and allocate a second IP address to the UE;

a sending module 1503, configured to send a create session response to the source SGW, where the create session response includes the uplink endpoint address carried by the second S5/S8 and the second IP address.

The present invention provides an SGW that can implement the functionality of the source SGW in the embodiment shown in fig. 8. The source SGW includes:

a receiving module, configured to receive a PDN connection modification request sent by an MME and including a downlink endpoint address carried by the first S1;

a processing module, configured to configure a downlink endpoint address carried by the second S5/S8 according to the PDN connectivity modification request;

a sending module, configured to send a session creation request to the target PGW, where the session creation request includes a downlink endpoint address carried in the second S5/S8;

the receiving module is further configured to receive a session creation response sent by the target PGW, where the session creation request includes an uplink endpoint address and a second IP address that are carried by the second S5/S8;

a sending module, configured to send a PDN connection modification response to the MME, where the PDN connection modification response includes a downlink endpoint address and a second IP address that are carried by the second S5/S8;

the receiving module is further configured to receive a bearer switching notification sent by the MME;

a modification module, configured to switch the first S5/S8 bearer to the second S5/S8 bearer according to the bearer switching notification.

Referring to fig. 16, the present invention provides an eNB1600 capable of implementing the functions of the eNB in the embodiment shown in fig. 8. The eNB1600 includes:

a receiving module 1601, configured to receive a PDN connection modification request sent by the MME, where the PDN connection modification request includes a second IP address;

a sending module 1602, configured to send a PGW reconfiguration notification including the second IP address to the UE, so that the UE maintains session connection with the application server according to the second IP address and the connection identifier;

the receiving module 1601 is further configured to receive a PGW reconfiguration notification acknowledgement message sent by the UE;

a sending module 1602, configured to send a PDN connection modification response to the MME.

The following describes a communication apparatus in an embodiment of the present invention from the perspective of a hardware device:

referring to fig. 17, the present invention provides an MME1700, and the MME shown in fig. 9 or fig. 13 may be implemented based on the structure of the MME 1700. The MME1700 includes one or more processors 1701 and one or more memories 1702, one or more network interfaces 1703 connected by a bus 1704. The one or more memories 1702 include computer program code and operational instructions. The processor 1701 may perform the operations of the MME in the embodiments shown in fig. 4 or fig. 8 by calling the computer program code stored in the memory 1702.

Referring to fig. 18, the present invention provides a UE1800, and the UE shown in fig. 10 or fig. 14 can be implemented based on the structure of the UE 1800. The UE wirelessly communicates with the eNB over a link. The UE1800 includes one or more processors 1801, one or more memories 1802, one or more input/output interfaces 1803, one or more display devices 1804, one or more transceivers 1805 (each including a transmitter Tx and a receiver Rx), connected via a bus 1806. One or more transceivers 1805 are connected to one or more antennas. Computer program code is included in the one or more memories 1802. The processor 1801 may perform the operations of the UE in the embodiments illustrated in fig. 4 or fig. 8 by invoking the computer program code stored by the memory 1802.

Referring to fig. 19, the present invention provides a PGW1900, and the PGW shown in fig. 11 or fig. 15 may be implemented based on the structure of the PGW 1900. The PGW1900 includes one or more processors 1901, one or more memories 1902, and one or more network interfaces 1903 connected by a bus 1904. The one or more memories include computer program code. The processor 1901 may perform the operations of the target PGW in the embodiments shown in fig. 4 or fig. 8 by calling the computer program code stored in the memory 1902.

The present invention also provides an SGW that includes one or more processors, one or more memories, and one or more network interfaces connected by a bus. The one or more memories include computer program code. The processor may perform the operations of the target SGW in the embodiment shown in fig. 4, or the operations of the source SGW in the embodiment shown in fig. 8, by invoking the computer program code stored by the memory.

Referring to fig. 20, the present invention provides an eNB2000, and the eNB shown in fig. 12 or fig. 16 may be implemented based on the structure of the eNB 2000. The eNB2000 provides radio access for UEs to the network and includes one or more processors 2001, one or more memories 2002, one or more network interfaces 2003, and one or more transceivers 2004 (each including a receiver Rx and a transmitter Tx), connected by a bus 2005. One or more transceivers 2004 are connected to an antenna or antenna array. The one or more processors 2001 include computer program code. The network interface 2003 is connected to the core network via a link (e.g., a link to the core network) or to other base stations via a wired or wireless link. The processor 2001 may perform the operations of the eNB in the embodiments shown in fig. 4 or fig. 8 by calling the computer program code stored in the memory 2002.

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 the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A packet data network gateway (PGW) switching method for maintaining service continuity is characterized in that a Packet Data Network (PDN) connection is established between User Equipment (UE) and an application server in a communication system applied by the method, the PDN connection comprises a first network Interconnection Protocol (IP) address of the UE, an evolved node B (eNB) and a source Serving Gateway (SGW) establish a first S1 bearer for the PDN connection, and the source SGW and the source PGW establish a first S5/S8 bearer for the PDN connection, and the method comprises the following steps:

a Mobile Management Entity (MME) determines a target PGW and a target SGW, wherein the target PGW is a PGW redistributed by the MME for PDN connection, and the target SGW is an SGW redistributed by the MME for PDN connection;

the MME sends a first create session request including a downlink endpoint address of a first S1 bearer to a target SGW, so that the target SGW sends a second create session request to the target PGW, the first create session request is used for the target SGW to configure an uplink endpoint address of a second S1 bearer and a downlink endpoint address of a second S5/S8 bearer, the second create session request is used for the target PGW to configure an uplink endpoint address of the second S5/S8 bearer and allocate a second IP address to the UE;

the MME receives a first create session response sent by the target SGW, where the first create session response includes the uplink endpoint address and the second IP address carried by the second S1;

the MME sends a PDN connection modification request comprising an uplink endpoint address and a second IP address of the second S1 bearer to the eNB, so that the eNB sends the second IP address to the UE, wherein the uplink endpoint address of the second S1 bearer is used for the eNB to modify the S1 bearer of the uplink data channel from the first S1 bearer to the second S1 bearer;

and the MME receives a PDN connection modification response sent by the eNB.

2. The method of claim 1, wherein after the MME receives the PDN connection modification response sent by the eNB, the method further comprises:

the MME sends a first delete session request comprising a bearer identifier to a source SGW, wherein the bearer identifier corresponds to the first S1 bearer and the first S5/S8 bearer, so that the source SGW sends a second delete session request comprising the bearer identifier to a source PGW, and the second delete session request is used for instructing the source PGW to delete an uplink endpoint address of the first S5/S8 bearer and release the first IP address;

the MME receives a first session deletion response sent by the source SGW, and the first session deletion response is generated by the source SGW after receiving a second session deletion response sent by the source PGW.

3. The method of claim 1 or 2, wherein the MME determining a target PGW and a target SGW comprises:

the MME selects a target PGW from the candidate PGWs according to at least one item of service statistical information, network topology, load balance, internal events or access point names; and/or the presence of a gas in the gas,

the MME selects a target SGW from the candidate SGWs according to at least one of network topology, load balancing or internal events.

4. A packet data network gateway (PGW) switching method for maintaining service continuity, wherein a Packet Data Network (PDN) connection is established between User Equipment (UE) and an application server in a communication system applied in the method, the PDN connection comprises a first network Interconnection Protocol (IP) address of the UE, an evolved node B (eNB) and a source Serving Gateway (SGW) establish a first S1 bearer for the PDN connection, and the source SGW and the source PGW establish a first S5/S8 bearer for the PDN connection, and the method comprises the following steps:

the UE receives a PGW reconfiguration notification including a second IP address from the eNB, the second IP address being allocated to the UE by a target PGW, the target PGW being different from the source PGW;

the UE generates an IP reconfiguration notification comprising the second IP address and a connection identifier;

the UE sends the IP reconfiguration notification to an application server, so that the application server keeps session connection with the UE according to the second IP address and the connection identifier;

the UE sends a PGW reconfiguration notification acknowledgement message to the eNB.

5. The method of claim 4, wherein the UE receiving the PGW reconfiguration notification including the second IP address from the eNB comprises: the UE receiving a PGW reconfiguration notification including a second IP address from the eNB through an RRC layer of a control plane protocol stack of the UE;

the UE generating an IP reconfiguration notification including the second IP address and a connection identity comprises: the UE acquires an IP available notification comprising the second IP address from a Radio Resource Control (RRC) layer of a control plane protocol stack of the UE through a flexible transport protocol (STP) layer of the user plane protocol stack of the UE, and generates an IP reconfiguration notification comprising the second IP address and a connection identifier;

the UE sending the IP reconfiguration notification to an application server includes: and the UE sends the IP reconfiguration notification to an STP layer of an application server through the STP layer of a user plane protocol stack of the UE.

6. The method of claim 4, wherein after the UE receives the PGW reconfiguration notification sent by the eNB, the method further comprises:

the UE deactivates the first IP address.

7. The method of any of claims 4 to 6, wherein the UE sending a PGW reconfiguration notification acknowledgement message to the eNB comprises:

starting a timer when the UE receives a PGW reconfiguration notification sent by the eNB; and when the timing duration of the timer is not less than the preset duration, the UE sends a PGW reconfiguration notification confirmation message to the eNB.

8. The method of any of claims 4 to 6, wherein the UE sending a PGW reconfiguration notification acknowledgement message to the eNB comprises:

and when the UE receives the IP reconfiguration notification confirmation message sent by the application server, the UE sends a PGW reconfiguration notification confirmation message to the eNB.

9. A packet data network gateway (PGW) switching method for maintaining service continuity, wherein a Packet Data Network (PDN) connection is established between User Equipment (UE) and an application server in a communication system applied in the method, the PDN connection comprises a first network Interconnection Protocol (IP) address of the UE, an evolved node B (eNB) and a source Serving Gateway (SGW) establish a first S1 bearer for the PDN connection, and the source SGW and the source PGW establish a first S5/S8 bearer for the PDN connection, and the method comprises the following steps:

the target PGW receives a second session creation request sent by the target SGW, wherein the second session creation request comprises a downlink endpoint address carried by a second S5/S8, and the target SGW is different from the source SGW;

the target PGW configures an uplink endpoint address carried by a second S5/S8 according to the downlink endpoint address carried by the second S5/S8 of the second create session request, and allocates a second IP address to the UE;

the target PGW sends a second create session response to the target SGW, where the second create session response includes the uplink endpoint address and the second IP address carried by the second S5/S8.

10. A packet data network gateway (PGW) switching method for maintaining service continuity, wherein a Packet Data Network (PDN) connection is established between User Equipment (UE) and an application server in a communication system applied in the method, the PDN connection comprises a first network Interconnection Protocol (IP) address of the UE, an evolved node B (eNB) and a source Serving Gateway (SGW) establish a first S1 bearer for the PDN connection, and the source SGW and the source PGW establish a first S5/S8 bearer for the PDN connection, and the method comprises the following steps:

the eNB receives a PDN connection modification request sent by an MME, wherein the PDN connection modification request comprises a second IP address and an uplink endpoint address carried by a second S1, so that the eNB configures a downlink endpoint address carried by a second S1 according to the uplink endpoint address carried by the second S1, and a target SGW is different from the source SGW;

the eNB sends a PGW reconfiguration notification including the second IP address to UE, so that the UE maintains session connection with the application server according to the second IP address and the connection identifier;

the eNB receives a PGW reconfiguration notification confirmation message sent by the UE, and modifies an S1 bearer in an uplink data channel of the UE from the first S1 bearer to the second S1 bearer according to an uplink endpoint address of the second S1 bearer, where an uplink endpoint and a downlink endpoint of the second S1 bearer are the target SGW and the eNB, respectively;

and the eNB sends a PDN connection modification response to the MME.

11. A packet data network gateway (PGW) switching method for maintaining service continuity, wherein a Packet Data Network (PDN) connection is established between User Equipment (UE) and an application server in a communication system applied in the method, the PDN connection comprises a first network Interconnection Protocol (IP) address of the UE, an evolved node B (eNB) and a source Serving Gateway (SGW) establish a first S1 bearer for the PDN connection, and the source SGW and the source PGW establish a first S5/S8 bearer for the PDN connection, and the method comprises the following steps:

a Mobile Management Entity (MME) determines a target PGW, wherein the target PGW is a PGW redistributed by the MME for PDN connection;

the MME sends a PDN connection modification request comprising a bearer identifier of the first S1 bearer to the source SGW, so that the source SGW sends a creation session request to the target PGW, wherein the PDN connection modification request is used for instructing the source SGW to use a downlink endpoint address of the first S5/S8 bearer as a downlink endpoint address of a second S5/S8 bearer, and the creation session request is used for instructing the target PGW to configure an uplink endpoint address of the second S5/S8 bearer and allocate a second IP address to the UE;

the MME receives a PDN connection modification response sent by the source SGW, wherein the PDN connection modification response comprises the second IP address;

the MME sends a PDN connection modification request comprising the second IP address to the eNB, so that the eNB sends a PGW reconfiguration notification comprising the second IP address to the UE, wherein the PGW reconfiguration notification is used for indicating the UE to modify the IP address of the PDN connection from the first IP address to the second IP address;

the MME receives a PDN connection modification response sent by the eNB and sends a bearer switching notification to the source SGW according to the PDN connection modification response, wherein the bearer switching notification is used for indicating the source SGW to switch the first S5/S8 bearer to the second S5/S8 bearer.

12. The method of claim 11, wherein after the MME receives the PDN connectivity modification response sent by the eNB, the method further comprises:

the MME sends a PDN connection deletion notification request comprising bearer identifications to a source SGW, wherein the bearer identifications correspond to the first S1 bearer and the first S5/S8 bearer, so that the source SGW sends a session deletion request comprising the bearer identifications to a source PGW, and the session deletion request is used for indicating the source PGW to delete an uplink endpoint address of the first S5/S8 bearer and release the first IP address;

and the MME receives a PDN connection deletion notification response sent by the source SGW, and the PDN connection deletion notification response is generated after the source SGW receives a session deletion response sent by the source PGW.

13. A packet data network gateway (PGW) switching method for maintaining service continuity, wherein a Packet Data Network (PDN) connection is established between User Equipment (UE) and an application server in a communication system applied in the method, the PDN connection comprises a first network Interconnection Protocol (IP) address of the UE, an evolved node B (eNB) and a source Serving Gateway (SGW) establish a first S1 bearer for the PDN connection, and the source SGW and the source PGW establish a first S5/S8 bearer for the PDN connection, and the method comprises the following steps:

the UE sends the PGW reconfiguration notification acknowledgement message to the eNB.

14. The method of claim 13, wherein receiving, by the UE, the PGW reconfiguration notification including the second IP address from the eNB comprises: the UE receiving a PGW reconfiguration notification including a second IP address from the eNB through an RRC layer of a control plane protocol stack of the UE;

the UE generating an IP reconfiguration notification including the second IP address and a connection identity comprises: the UE acquires an IP available notification comprising the second IP address from an RRC layer of a control plane protocol stack of the UE through an STP layer of the user plane protocol stack of the UE, and generates an IP reconfiguration notification comprising the second IP address and a connection identifier;

the UE sending the IP reconfiguration notification to an application server includes: and sending the IP reconfiguration notification to an STP layer of an application server through the STP layer of the user plane protocol stack of the UE.

15. The method according to claim 13 or 14, wherein after the UE receives the PGW reconfiguration notification sent by the eNB, the method further comprises:

the UE deactivates the first IP address.

16. A packet data network gateway (PGW) switching method for maintaining service continuity, wherein a Packet Data Network (PDN) connection is established between User Equipment (UE) and an application server in a communication system applied in the method, the PDN connection comprises a first network Interconnection Protocol (IP) address of the UE, an evolved node B (eNB) and a source Serving Gateway (SGW) establish a first S1 bearer for the PDN connection, and the source SGW and the source PGW establish a first S5/S8 bearer for the PDN connection, and the method comprises the following steps:

a target PGW receives a session creation request which is sent by a source SGW and comprises a downlink endpoint address carried by a second S5/S8, wherein the bearer identification carried by the second S5/S8 is the same as the bearer identification carried by the first S5/S8;

the target PGW configures the uplink endpoint address carried by the second S5/S8 according to the downlink endpoint address carried by the second S5/S8, and allocates a second IP address to the UE;

the target PGW sends a create session response to the source SGW, where the create session response includes the uplink endpoint address and the second IP address carried by the second S5/S8.

17. A packet data network gateway (PGW) switching method for maintaining service continuity, wherein a Packet Data Network (PDN) connection is established between User Equipment (UE) and an application server in a communication system applied in the method, the PDN connection comprises a first network Interconnection Protocol (IP) address of the UE, an evolved node B (eNB) and a source Serving Gateway (SGW) establish a first S1 bearer for the PDN connection, and the source SGW and the source PGW establish a first S5/S8 bearer for the PDN connection, and the method comprises the following steps:

the eNB receives a PDN connection modification request sent by an MME, wherein the PDN connection modification request comprises a second IP address;

the eNB sends a PGW reconfiguration notification including the second IP address to UE, so that the UE maintains session connection with an application server according to the second IP address and a connection identifier;

the eNB receives a PGW reconfiguration notification confirmation message sent by the UE;

and the eNB sends a PDN connection modification response to the MME.

18. A mobility management entity, MME, comprising:

a determining module, configured to determine a target PGW and a target SGW, where the target PGW is a PGW reallocated for PDN connection by the MME, and the target SGW is an SGW reallocated for PDN connection by the MME;

a sending module, configured to send a first create session request including a downstream endpoint address of a first S1 bearer to a target SGW, so that the target SGW sends a second create session request to the target PGW, where the first create session request is used to instruct the target SGW to configure an upstream endpoint address of a second S1 bearer and a downstream endpoint address of a second S5/S8 bearer according to the downstream endpoint address of the first S1 bearer, and the second create session request is used to instruct the target PGW to configure an upstream endpoint address of the second S5/S8 bearer and allocate a second IP address to the UE;

a receiving module, configured to receive a first create session response sent by the target SGW, where the first create session response includes the uplink endpoint address and the second IP address that are carried by the second S1;

the sending module is further configured to send a PDN connection modification request including the uplink endpoint address and the second IP address of the second S1 bearer to the eNB, so that the eNB sends the second IP address to the UE, and modifies the S1 bearer of the uplink data channel from the first S1 bearer to the second S1 bearer according to the uplink endpoint address of the second S1 bearer;

the receiving module is further configured to receive a PDN connection modification response sent by the eNB.

19. The MME of claim 18,

the sending module is further configured to send, after the receiving module receives the PDN connection modification response sent by the eNB, a first delete session request including a bearer identifier to a source SGW, where the bearer identifier corresponds to the first S1 bearer and the first S5/S8 bearer, so that the source SGW sends, to a source PGW, a second delete session request including the bearer identifier, where the second delete session request is used to instruct the source PGW to delete an uplink endpoint address of the first S5/S8 bearer and release the first IP address;

the receiving module is further configured to receive a first delete session response sent by the source SGW, where the first delete session response is generated after the source SGW receives a second delete session response sent by the source PGW.

20. The MME of claim 18 or 19, wherein the determining module is specifically configured to select a target PGW from the candidate PGWs according to at least one of traffic statistics information, network topology, load balancing, internal events, or access point names; and/or selecting a target SGW from the candidate SGWs based on at least one of network topology, load balancing, or internal events.

21. A User Equipment (UE), comprising:

a receiving module, configured to receive a PGW reconfiguration notification including a second IP address from an eNB, where the second IP address is allocated to the UE by a target PGW, and the target PGW is different from a source PGW;

a generating module, configured to generate an IP reconfiguration notification including the second IP address and a connection identifier;

a sending module, configured to send the IP reconfiguration notification to an application server, so that the application server maintains session connection with the UE according to the second IP address and the connection identifier;

the sending module is further configured to send the PGW reconfiguration notification acknowledgement message to the eNB.

22. The UE of claim 21, wherein the receiving module is specifically configured to receive, from the eNB through an RRC layer of a control plane protocol stack of the UE, a PGW reconfiguration notification including a second IP address;

the generating module is specifically configured to acquire, through an STP layer of a user plane protocol stack of the UE, an IP available notification including the second IP address from an RRC layer of a control plane protocol stack of the UE, and generate an IP reconfiguration notification including the second IP address and a connection identifier;

the sending module is specifically configured to send the IP reconfiguration notification to an STP layer of an application server through an STP layer of a user plane protocol stack of the UE.

23. The UE of claim 21, wherein the UE further comprises:

a deactivation module, configured to deactivate the first IP address after the receiving module receives the PGW reconfiguration notification sent by the eNB.

24. The UE according to any one of claims 21 to 23, wherein the sending module is specifically configured to start a timer when the receiving module receives the PGW reconfiguration notification sent by the eNB; and when the timing duration of the timer is not less than the preset duration, sending a PGW reconfiguration notification confirmation message to the eNB.

25. The UE according to any one of claims 21 to 23, wherein the sending module is specifically configured to send a PGW reconfiguration notification acknowledgment message to the eNB when the receiving module receives the IP reconfiguration notification acknowledgment message sent by the application server.

26. A packet data network gateway, PGW, comprising:

a receiving module, configured to receive a second create session request sent by a target SGW, where the second create session request includes a downstream endpoint address carried by a second S5/S8, and the target SGW is different from the source SGW;

a processing module, configured to configure an uplink endpoint address carried by the second S5/S8 according to the second create session request, and allocate a second IP address to the UE;

a sending module, configured to send a second create session response to the target SGW, where the second create session response includes the uplink endpoint address and the second IP address carried in the second S5/S8.

27. An evolved node B, eNB, comprising:

a receiving module, configured to receive a PDN connection modification request sent by an MME, where the PDN connection modification request includes a second IP address and an uplink endpoint address carried by a second S1, and a target SGW is different from a source SGW;

a sending module, configured to send a PGW reconfiguration notification including the second IP address to a UE, so that the UE maintains session connection with an application server according to the second IP address and a connection identifier;

the receiving module is further configured to receive a PGW reconfiguration notification acknowledgement message sent by the UE;

a modification module, configured to modify an S1 bearer in an uplink data channel of the UE from a first S1 bearer to a second S1 bearer according to an uplink endpoint address of the second S1 bearer, where an uplink endpoint and a downlink endpoint of the second S1 bearer are the target SGW and the eNB, respectively;

the sending module is further configured to send a PDN connection modification response to the MME.

28. A mobility management entity, MME, comprising:

a determining module, configured to determine a target PGW, where the target PGW is a PGW that is reallocated for PDN connection by the MME;

a sending module, configured to send a modified PDN connection request including a bearer identifier of a first S1 bearer to a source SGW, so that the source SGW sends a create session request to a target PGW, where the modified PDN connection request is used to instruct the source SGW to use a downlink endpoint address of a first S5/S8 bearer as a downlink endpoint address of a second S5/S8 bearer, and the create session request is used to instruct the target PGW to configure an uplink endpoint address of the second S5/S8 bearer and allocate a second IP address to a UE;

a receiving module, configured to receive a PDN modification connection response sent by the source SGW, where the PDN modification connection response includes an uplink endpoint address and a second IP address that are carried by the second S1;

the sending module is further configured to send a PDN connection modification request including the second IP address to an eNB, so that the eNB sends a PGW reconfiguration notification including the second IP address to the UE, where the PGW reconfiguration notification is used to instruct the UE to modify an IP address of a PDN connection from a first IP address to the second IP address;

the receiving module is further configured to receive a PDN connection modification response sent by the eNB;

the sending module is further configured to send a bearer handover notification to the source SGW according to the PDN connection modification response, where the bearer handover notification is used to instruct the source SGW to handover the first S5/S8 bearer to the second S5/S8 bearer.

29. The MME of claim 28,

the sending module is further configured to send, after the MME receives the PDN connection modification response sent by the eNB, a PDN connection deletion notification request including a bearer identifier to a source SGW, so that the source SGW sends a session deletion request including the bearer identifier to a source PGW, where the session deletion request is used to instruct the source PGW to delete the uplink endpoint address of the first S5/S8 bearer, and release the first IP address;

the receiving module is further configured to receive a PDN connection deletion notification response sent by the source SGW, where the PDN connection deletion notification response is generated after the source SGW receives the session deletion response sent by the source PGW.

30. A User Equipment (UE), comprising:

31. The UE of claim 30,

the receiving module is specifically configured to receive, from the eNB through an RRC layer of a control plane protocol stack of the UE, a PGW reconfiguration notification including a second IP address;

the generating module is specifically configured to acquire, by using an STP layer of a user plane protocol stack of the UE, an IP available notification including the second IP address from an RRC layer of a control plane protocol stack of the UE, and generate an IP reconfiguration notification including the second IP address and a connection identifier;

32. The UE of claim 30 or 31, wherein the UE further comprises:

33. A packet data network gateway, PGW, comprising:

a receiving module, configured to receive a session creation request sent by a source SGW, where the session creation request includes a downlink endpoint address of a second S5/S8 bearer, and a bearer identifier of the second S5/S8 bearer is the same as a bearer identifier of a first S5/S8 bearer;

a processing module, configured to configure an uplink endpoint address carried in the second S5/S8 according to the downlink endpoint address carried in the second S5/S8, and allocate a second IP address to the UE;

a sending module, configured to send a create session response to the source SGW, where the create session response includes the uplink endpoint address and the second IP address carried in the second S5/S8.

34. An evolved node B, eNB, comprising:

a receiving module, configured to receive a PDN connection modification request sent by an MME, where the PDN connection modification request includes a second IP address;