CN106922019B

CN106922019B - Data transmission method and service capability open network element SCEF

Info

Publication number: CN106922019B
Application number: CN201511001128.0A
Authority: CN
Inventors: 蔡慧
Original assignee: China Mobile Communications Group Co Ltd
Current assignee: China Mobile Communications Group Co Ltd
Priority date: 2015-12-28
Filing date: 2015-12-28
Publication date: 2020-05-29
Anticipated expiration: 2035-12-28
Also published as: CN106922019A

Abstract

The invention discloses a data transmission method, which comprises the following steps: acquiring an identifier of a terminal UE to receive a data packet; determining a first network element matched with the UE of the data packet to be received according to the identification of the UE; and sending a link establishment request to the first network element so that the first network element initiates the link establishment request for establishing a data link for transmitting the data packet to the UE which is to receive the data packet. The SCEF is also disclosed, and can reduce the transmission delay of data and the load of a PGW/SGW network element.

Description

Data transmission method and service capability open network element SCEF

Technical Field

The present invention relates to the field of communications technologies, and in particular, to a data transmission method and a Service Capability Exposure Function (SCEF).

Background

In a communication system, in order to save transmission resources of a network, when a terminal (UE) connected in the network is in an Idle state (Idle state), that is, there is no transmission or reception of data, a data channel used by the terminal is usually disconnected. The Idle state of the UE is beneficial to saving power, and can also avoid a handover processing procedure frequently initiated to the network due to the movement of the UE.

Fig. 1 is a schematic diagram illustrating an implementation of a data transmission method in the prior art. As shown in fig. 1, when the UE is in the Idle state, and when the server sends a packet to the UE, a Public Data Network (PDN) GateWay (PGW, PDN GateWay) forwards the packet to a Serving GateWay (SGW), and the SGW receives and buffers the packet (downlink packet); the SGW sends a Downlink Data Notification message (Downlink Data Notification) to a Mobility Management Entity (MME) to which the UE is attached, and the MME sends a feedback ACK signal to the SGW. The MME sends a Paging message to an eNodeB where the UE resides, and the eNodeB sends the Paging message to the UE to trigger the UE to initiate a Paging Service Request (Service Request) to a network side, perform a data link establishment procedure, establish a connection between the UE and the network side (the foregoing scheme may be regarded as a process of establishing a transmission link between the UE and a server), and send a cached data packet to the UE through the data link SGW. The foregoing scheme may also be considered a procedure for paging a terminal.

In an LTE network, a link established between an eNodeB and an SGW is referred to as a data plane link, and the aforementioned process of establishing a data channel for a terminal in an Idle state is to trigger an MME from the data plane to page the UE. Meanwhile, by adopting the way that the PGW/SGW network element triggers the MME to perform paging of the terminal, the PGW/SGW also needs to temporarily cache data sent from the server to the UE, which is heavy for the PGW/SGW network element.

Disclosure of Invention

In order to solve the existing technical problem, embodiments of the present invention provide a data transmission method and an SCEF, which can at least reduce transmission delay of data and reduce load of a PGW/SGW network element.

The technical scheme of the embodiment of the invention is realized as follows:

an embodiment of the present invention further provides a data transmission method, where the method includes:

acquiring an identifier of a terminal UE to receive a data packet;

determining a first network element matched with the UE of the data packet to be received according to the identification of the UE;

and sending a link establishment request to the first network element so that the first network element initiates the link establishment request for establishing a data link for transmitting the data packet to the UE which is to receive the data packet.

In the foregoing solution, before determining, according to the identifier of the UE, a first network element that is matched with the UE that is to receive the data packet, the method further includes:

acquiring a first corresponding relation, wherein the first corresponding relation records the corresponding relation between the identifier of the UE and the identifier of a first network element attached to the UE;

correspondingly, the determining, according to the identifier of the UE, the first network element that matches the UE that is to receive the data packet includes:

determining a first network element identifier corresponding to the identifier of the UE of the data packet to be received in the acquired first corresponding relation to obtain a first identifier;

and determining the first network element with the first identifier as the first network element matched with the UE of the data packet to be received.

In the foregoing scheme, the obtaining the first corresponding relationship includes:

and receiving the first corresponding relation reported by the first network element and/or a user home server (HSS).

In the foregoing solution, the obtaining the identifier of the UE that is to receive the data packet includes:

receiving the identifier of the UE of the data packet to be received, which is sent by the server;

correspondingly, the link establishment request initiated by the first network element to the UE to receive the data packet is a request for establishing a transmission link between the server and the UE to receive the data packet.

In the foregoing solution, before sending the link establishment request to the first network element, the method further includes:

receiving the state of the UE of the data packet to be received reported by the first network element;

and if the state of the UE is an Idle state, sending the link establishment request to the first network element.

In the above scheme, the method further comprises:

and if the first network element attached to the UE of the data packet to be received is changed, updating the identifier of the first network element corresponding to the UE of the data packet to be received as the identifier of the first network element after the attachment change in the first corresponding relation.

In the foregoing solution, the first network element is a mobility management entity MME or a software defined network controller SDNcontroller.

The embodiment of the present invention further provides a capability openness network element SCEF, where the SCEF includes:

a first obtaining unit, configured to obtain an identifier of a terminal UE that is to receive a data packet;

a first determining unit, configured to determine, according to the identifier of the UE, a first network element that is matched with the UE that is to receive the data packet;

a first sending unit, configured to send a link establishment request to the first network element, so that the first network element initiates the link establishment request for establishing a data link for transmitting the data packet to the UE that is to receive the data packet.

In the foregoing solution, the SCEF further includes:

a second obtaining unit, configured to obtain a first corresponding relationship, where the first corresponding relationship records a corresponding relationship between an identifier of the UE and an identifier of a first network element to which the UE is attached;

correspondingly, the first determining unit is configured to determine, in the obtained first corresponding relationship, a first network element identifier corresponding to an identifier of the UE that is to receive the data packet, to obtain a first identifier; and determining the first network element with the first identifier as the first network element matched with the UE of the data packet to be received.

In the foregoing solution, the second obtaining unit is further configured to:

In the above solution, the first obtaining unit is configured to receive an identifier of the UE that is to receive the data packet and is sent by the server;

In the foregoing solution, the SCEF further includes a first receiving unit, configured to receive a state of the UE to receive the data packet, where the state is reported by the first network element;

correspondingly, the first sending unit is configured to send the link establishment request to the first network element if the state of the UE is an Idle state.

In the foregoing solution, the SCEF further includes a first updating unit, configured to update, in the first corresponding relationship, an identifier of the first network element corresponding to the UE that is to receive the data packet to be an identifier of the first network element after attachment change if the first network element to which the UE that is to receive the data packet is attached changes.

The data transmission method and the SCEF of the embodiment of the invention comprise the following steps: acquiring an identifier of a terminal UE to receive a data packet; determining a first network element matched with the UE of the data packet to be received according to the identification of the UE; and sending a link establishment request to the first network element so that the first network element initiates the link establishment request for establishing a data link for transmitting the data packet to the UE which is to receive the data packet. The invention can establish a data link from a signaling plane, reduce the transmission delay of data and lighten the load of a PGW/SGW network element.

Drawings

Fig. 1 is a schematic diagram illustrating a data transmission method in the prior art;

fig. 2 is a schematic flow chart illustrating an implementation of a data transmission method according to an embodiment of the present invention;

fig. 3 is a first flowchart illustrating a specific implementation of a data transmission method according to an embodiment of the present invention;

fig. 4 is a schematic diagram of a specific implementation flow of the data transmission method in the embodiment of the present invention;

fig. 5 is a schematic flow chart illustrating a specific implementation of the data transmission method according to the embodiment of the present invention;

fig. 6 is a schematic structural diagram of SCEF according to an embodiment of the present invention.

Detailed Description

The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, and it should be understood that the preferred embodiments described below are only for the purpose of illustrating and explaining the present invention, and are not to be construed as limiting the present invention.

The embodiment of the data transmission method provided by the invention is applied to the SCEF. Fig. 2 is a schematic flow chart illustrating an implementation of a data transmission method according to an embodiment of the present invention; as shown in fig. 2, the method includes:

step 201: acquiring an identifier of a terminal UE to receive a data packet;

here, the server needs to send a downlink packet to the UE in the Idle state, and first sends an identifier of the UE to the SCEF, and the SCEF receives the identifier of the UE, where the identifier of the UE may be an International Mobile Subscriber Identity (IMSI) of the UE, a Temporary Identity (TMSI), or a SIM Number of a Subscriber Identity Module (SIM) inserted by the UE.

Step 202: determining a first network element matched with the UE of the data packet to be received according to the identification of the UE;

here, the first network element is a network element having a mobility management function, and may be an MME, or may be a software defined network controller (SDN controller). Taking a first network element as an MME, the SCEF obtains a first corresponding relationship, where the first corresponding relationship records a corresponding relationship between an identifier of the UE and an identifier of an MME to which the UE is attached, and after receiving an identifier of a UE to which a server sends a data packet to the UE in advance, the SCEF determines, in the obtained first corresponding relationship, an MME identifier corresponding to the identifier of the UE to receive the data packet to obtain a first identifier, and determines that the MME having the first identifier is an MME matched with the UE to receive the data packet, that is, the MME having the first identifier is the MME to which the UE is attached. The first corresponding relationship is a first corresponding relationship reported by the SCEF receiving MME and/or the Home Subscriber Server (HSS). Further, after the UE, the eNodeB and the MME complete the access authentication and authorization procedure of the UE, the UE determines the MME to which the UE should attach, and the MME to which the UE attaches stores the identity of the UE and the identity of the UE attached thereto to form a first corresponding relationship, and the HSS also records the first corresponding relationship. The MME identification may be a unique number of the MME in the network, such as an internet protocol IP address of the MME. If the MME to which the UE is attached changes, the SCEF updates the MME identifier corresponding to the identity of the UE to be the identity of the MME after the attachment change in the first corresponding relation.

Step 203: and sending a link establishment request to the first network element so that the first network element initiates the link establishment request for establishing a data link for transmitting the data packet to the UE which is to receive the data packet.

Here, the link establishment request initiated by the MME to a UE that pre-sends a data packet to a server is a request to establish a transmission link between the server and the UE. The transmission link is a data plane transmission link established among the UE, eNodeB and SGW, and the server can transmit downlink data packets to the UE through the transmission link. As should be known to those skilled in the art, the link establishment request is a Paging message, and the MME initiates the Paging message to the eNodeB where the UE resides is actually to perform a procedure of Paging the UE.

Before sending a link establishment request to the MME, the method further comprises: the SCEF receives the state of the UE of the data packet to be received, which is reported by the MME; and if the state of the UE is the Idle state, the SCEF sends the link establishment request to the MME.

In the embodiment of the invention, a server needs to send a downlink data packet to the UE in the Idle state, the SCEF obtains the identifier of the UE capable of receiving the data packet from the server, finds the MME to which the UE is attached in the first corresponding relationship, sends a link establishment request capable of establishing a data link for transmitting the data packet to the MME, and transmits the data packet from the server to the UE through the established data link. Compared with the prior art in which a server directly transmits a data packet to an SGW/PGW cache and a data plane triggers an MME to page a UE, the present embodiment pages the UE in Idle state from a signaling plane to establish a transmission link for the data packet, and transmits the data packet from the server to the UE through the transmission link after the transmission link is established. In the foregoing scheme, the process of acquiring the identifier of the UE through the SCEF, determining the MME matched with the identifier, and sending the link establishment request to the MME may be regarded as a process of paging the UE in the Idle state from the signaling plane, and the data packet to be transmitted does not need to be cached in the SGW/PGW, so that the load of the PGW/SGW network element can be greatly alleviated, and the transmission delay can be reduced.

The present invention will be further described with reference to fig. 3 to 5. In fig. 3 to 5, the first network element is described as an MME.

In fig. 3, the MME is triggered to perform a paging procedure for the UE1 for the HSS.

In particular, the method comprises the following steps of,

step 301: HSS and server make user paging ability open contract;

here, the HSS and the server agree on the type of UE that can page the UE from the signaling plane, i.e., which UE is qualified to perform the subsequent steps 304 to 314.

Step 302: executing a user access authentication authorization process;

here, the access authentication authorization procedure mainly includes procedures such as initial attachment, validity authentication, security authentication, etc. to the UE, in which the UE can complete attachment to a certain MME, the MME stores its own identity and the identity of the UE attached thereto to obtain a first corresponding relationship, and the HSS stores the first corresponding relationship. For the access authentication and authorization process, please refer to the related description, which is not described herein.

Step 303: the HSS judges whether the UE1 has a user paging capability opening function or not;

if yes, go on to step 304;

otherwise, ending the process;

step 304: the HSS informs the MME to execute a paging capacity opening process to the SCEF;

step 305: the MME reports the first corresponding relation to the SCEF;

step 306: the MME reports the state of the UE to the SCEF;

here, the UE may be in Idle and connected states; because the present solution is a process of paging the UE in Idle state from the signaling plane, the UE state reported by the MME to the SCEF is preferably in Idle state.

Step 307: the server sends the identity of the UE1, and the SCEF receives the identity;

here, the server needs to send a downlink packet to the UE1, and first sends the identity of the UE1 to the SCEF. Preferably, in view of the limited network resources, if the UE1 does not perform data transmission any more after the downlink packet transmission is completed, it needs to trigger the UE to enter the Idle state, and when the server sends the identifier of the UE1 to the SCEF, it also needs to instruct the UE1 to enter the Idle state, so that the UE1 enters the Idle state when the time comes, so that the network resources occupied by the UE1 before can be free for other terminals to use.

Step 308: in the first corresponding relation, the SCEF searches for an MME identifier corresponding to the identifier of the UE1 to obtain a first identifier;

step 309: the SCEF sends a link establishment request to the MME with the first identifier;

step 310: the MME sends a Paging message to an eNodeB where the UE1 resides, and the eNodeB sends the Paging message to the UE1 to trigger the UE1 to initiate a Paging Service Request (Service Request) to the network side, perform a data link establishment procedure, and establish a connection between the UE1 and the network side.

Here, step 310 is a process of paging the UE by the MME, and for a detailed description, refer to the related description in the prior art, which is not described herein again.

Step 311: the MME informs the SCEF that a data link is established;

step 312: the SCEF informs the server that a data link is established;

step 313: the server transmits the data packets to the UE1 over the established data link.

If the MME where the UE1 resides changes, further comprising step 314: the MME after the attachment change sends its own identity to the SCEF, and the SCEF updates the MME identity corresponding to the identity of the UE1 to the MME identity after the attachment change in the first correspondence.

In the foregoing solution, the HSS triggers a process of paging the UE by the MME, acquires the identifier of the UE1 through the SCEF, determines the MME matching the identifier, sends a link establishment request to the MME to complete establishment of a transmission link between the UE1 and the server, and transmits a data packet from the server to the UE1 through the transmission link. The paging of the UE in the Idle state is realized from the signaling side, the data packet to be transmitted does not need to be cached in the SGW/PGW, the load of a PGW/SGW network element can be greatly relieved, and the transmission delay is reduced.

In fig. 4, the HSS performs a paging capability opening procedure towards the SCEF.

In particular, the method comprises the following steps of,

step 401: HSS and server make user paging ability open contract;

here, the HSS and the server agree on the type of UE that can page the UE from the signaling plane, i.e., which UE is qualified to perform the subsequent steps 404 to 412.

Step 402: executing a user access authentication authorization process;

here, the access authentication authorization procedure mainly includes procedures such as initial attachment, validity authentication, security authentication, etc. of the UE, in which the UE may complete attachment to a certain MME, the MME stores its own identity and the identity of the UE attached thereto to obtain a first corresponding relationship, and the HSS stores the first corresponding relationship. For the access authentication and authorization process, please refer to the related description, which is not described herein.

Step 403: the HSS judges whether the UE1 has a user paging capability opening function or not;

if yes, go on to step 404;

otherwise, ending the process;

step 404: HSS reports the first corresponding relation to SCEF;

step 405: the server sends the identity of the UE1, and the SCEF receives the identity;

here, the server needs to send a downlink packet to the UE1 in Idle state, and first sends the identifier of the UE1 to the SCEF. Preferably, in view of the limited network resources, if the UE1 does not perform data transmission any more after the downlink packet transmission is completed, it needs to trigger it to enter the Idle state, and when the server sends the identity of the UE1 to the SCEF, it also needs to indicate the time when the UE1 enters the Idle state, so that the UE1 enters the Idle state when the time comes.

Step 406: in the first corresponding relation, the SCEF searches for an MME identifier corresponding to the identifier of the UE1 to obtain a first identifier;

step 407: the SCEF sends a link establishment request to the MME with the first identifier;

step 408: the MME sends a Paging message to an eNodeB where the UE1 resides, and the eNodeB sends the Paging message to the UE1 to trigger the UE1 to initiate a Paging Service Request (Service Request) to the network side, perform a data link establishment procedure, and establish a connection between the UE1 and the network side.

Step 409: the MME informs the SCEF that a data link is established;

step 410: the SCEF informs the server that a data link is established;

step 411: the server transmits the data packets to the UE1 over the established data link.

If the MME where the UE1 resides changes, the method further includes the step 412: the MME after the attachment change sends its own identity to the SCEF, and the SCEF updates the MME identity corresponding to the identity of the UE1 to the MME identity after the attachment change in the first correspondence.

In the foregoing solution, the HSS performs a paging capability opening procedure to the SCEF, acquires the identifier of the UE1 through the SCEF, determines the MME matching the identifier, sends a link establishment request to the MME to complete establishment of a transmission link between the UE1 and the server, and transmits a data packet from the server to the UE1 through the transmission link. The paging of the UE in the Idle state is realized from the signaling side, the data packet to be transmitted does not need to be cached in the SGW/PGW, the load of a PGW/SGW network element can be greatly relieved, and the transmission delay is reduced.

In fig. 5, the MME is triggered for the server to perform the paging procedure for the UE 1.

In particular, the method comprises the following steps of,

step 501: HSS and server make user paging ability open contract;

here, the HSS and the server agree on the type of UE that can page the UE from the signaling plane, i.e., which UE is qualified to perform the subsequent steps 506 to 511.

Step 502: executing a user access authentication authorization process;

Step 503: the server sends the identity of the UE1, and the SCEF receives the identity;

step 504: the SCEF sends the identity of the UE1 to the HSS;

step 505: the HSS judges whether the UE1 has a user paging capability opening function or not;

if yes, go on to step 506;

otherwise, ending the process;

step 506: HSS sends link establishment request to MME;

step 507: the MME judges whether the UE1 is in an Idle state;

if the MME is in the Idle state, executing step 508;

otherwise, go to step 509;

step 508: the MME sends a Paging message to an eNodeB where the UE1 resides, and the eNodeB sends the Paging message to the UE1 to trigger the UE1 to initiate a Service Request to the network side, execute a data link establishment procedure, and establish a connection between the UE1 and the network side;

step 509: the MME informs the SCEF that a data link is established;

step 510: the SCEF informs the server that a data link is established;

step 511: the server transmits the data packets to the UE1 over the established data link.

If the MME where the UE1 resides changes, the method further includes step 512: the MME after the attachment change sends its own identity to the SCEF, and the SCEF updates the MME identity corresponding to the identity of the UE1 to the MME identity after the attachment change in the first correspondence.

In the foregoing solution, when the MME receives the link establishment request sent by the HSS and determines that the UE1 is in the Idle state, the MME performs a paging procedure on the UE1 to complete establishment of a transmission link between the UE1 and the server, and transmits a data packet from the server to the UE1 through the transmission link. The paging of the UE in the Idle state is realized from the signaling side, the data packet to be transmitted does not need to be cached in the SGW/PGW, the load of a PGW/SGW network element can be greatly relieved, and the transmission delay is reduced.

It should be noted that the functions performed by the SCEF may be implemented by a separate SCEF network element, or may be implemented by being integrated in the SGW/PGW.

Based on the foregoing data transmission method, an embodiment of the present invention further provides an capability openness network element SCEF, where as shown in fig. 6, the SCEF includes:

a first obtaining unit 601, configured to obtain an identifier of a terminal UE that is to receive a data packet;

a first determining unit 602, configured to determine, according to the identifier of the UE, a first network element that matches the UE that is to receive the data packet;

a first sending unit 603, configured to send a link establishment request to the first network element, so that the first network element initiates the link establishment request for establishing a data link for transmitting the data packet to the UE that is to receive the data packet.

Wherein the SCEF further comprises: a second obtaining unit, a first receiving unit and a first updating unit (none shown in fig. 6); wherein the content of the first and second substances,

correspondingly, the first determining unit 602 is configured to determine, in the obtained first corresponding relationship, a first network element identifier corresponding to an identifier of the UE that is to receive the data packet, to obtain a first identifier; and determining the first network element with the first identifier as the first network element matched with the UE of the data packet to be received.

Wherein the second obtaining unit is further configured to: and receiving the first corresponding relation reported by the first network element and/or a user home server (HSS).

The first obtaining unit 601 is configured to receive an identifier of the UE that is to receive the data packet and is sent by the server;

The first receiving unit is configured to receive a state of the UE to receive the data packet, where the state is reported by the first network element;

correspondingly, the first sending unit 603 is configured to send the link establishment request to the first network element if the state of the UE is an Idle state.

The first updating unit is configured to update, in the first corresponding relationship, the identifier of the first network element corresponding to the UE that is to receive the data packet to the identifier of the first network element after attachment change if the first network element to which the UE that is to receive the data packet is attached changes.

Those skilled in the art will appreciate that the functions implemented by the processing units in the SCEF shown in fig. 6 can be understood by referring to the related description of the methods shown in fig. 2-5. Those skilled in the art will appreciate that the functions of the processing units in the SCEF shown in fig. 2 may be implemented by a program running on a processor, or may be implemented by specific logic circuits.

In the SCEF according to the embodiments of the present invention, since the principle of solving the problem by the SCEF is similar to that of the data transmission method, the implementation process and the implementation principle of the SCEF can be described by referring to the implementation process and the implementation principle of the method, and repeated descriptions are omitted.

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

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

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

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

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention.

Claims

1. A method of data transmission, the method comprising:

acquiring an identifier of a terminal UE to receive a data packet;

determining a first network element matched with the UE of the data packet to be received according to the identifier of the UE and the first corresponding relation; wherein, the first corresponding relation records the corresponding relation between the identifier of the UE and the identifier of the first network element attached to the UE;

and sending a link establishment request to the determined first network element so that the first network element initiates the link establishment request for establishing a data link for transmitting the data packet to the UE which is to receive the data packet.

2. The method of claim 1, wherein before determining the first network element matching the UE to receive the data packet according to the identity of the UE, the method further comprises:

acquiring a first corresponding relation;

3. The method of claim 2, wherein obtaining the first correspondence comprises:

4. The method of claim 1, wherein the obtaining the identity of the UE that is to receive the data packet comprises:

5. The method of claim 1, wherein prior to sending the link establishment request to the first network element, the method further comprises:

6. A method according to claim 2 or 3, characterized in that the method further comprises:

7. The method of claim 1, wherein the first network element is a Mobility Management Entity (MME) or a software defined network controller (SDN controller).

8. A capability openness network element, SCEF, comprising:

a first determining unit, configured to determine, according to the identifier of the UE and the first corresponding relationship, a first network element that is matched with the UE that is to receive the data packet; wherein, the first corresponding relation records the corresponding relation between the identifier of the UE and the identifier of the first network element attached to the UE;

9. The SCEF according to claim 8, further comprising:

a second obtaining unit configured to obtain the first corresponding relationship;

10. The SCEF according to claim 9, wherein the second obtaining unit is further configured to:

11. The SCEF according to claim 8, wherein the first obtaining unit is configured to receive an identifier of the UE that is to receive the data packet and sent by the server;

12. The SCEF according to claim 8, further comprising a first receiving unit, configured to receive the status of the UE to receive the data packet, where the status is reported by the first network element;

13. The SCEF according to claim 9 or 10, further comprising a first updating unit, configured to update, in the first corresponding relationship, the identifier of the first network element corresponding to the UE that is to receive the data packet to be the identifier of the first network element after attachment change, if the first network element to which the UE that is to receive the data packet is attached changes.

14. The SCEF according to claim 8, wherein the first network element is a mobility management network element MME or a software defined network controller SDN controller.