KR20130085477A - Method and apparatus of processing a data packet in mobile communacation system - Google Patents

Abstract

PURPOSE: Data packet processing method and device thereof of a mobile communication system are provided to prevent packet loss according to network reactivation. CONSTITUTION: A gateway GPRS support node (GGSN) (500) includes a tunnel forming unit (510), a packet confirmation unit (520), a transmission unit (530) and a reception unit (540). The tunnel forming unit forms a direct tunnel of a data region with a radio network controller (RNC) (506) by signaling through serving GPRS support node (SGSN) (550) and GPRS tunneling protocol (GTP)-C protocol. The reception unit receives a downlink data packet with respect to a sleep mode terminal transmitted to the SGSN in a state in which a data session with respect to the terminal from the SGSN. The packet confirmation unit confirms indicator and data size recorded in a header of the data packet received by the reception unit. The transmission unit transmits the downlink data packet to the RNC using the direct tunnel formed by the tunnel forming unit when the packet confirmation unit decides to transmit the downlink data packet. [Reference numerals] (500) Package exchange support node; (510) Tunnel forming unit; (520) Packet confirmation unit; (530) Transmission unit; (540) Reception unit

Description

Method and apparatus for processing data packet in mobile communication system {Method and Apparatus of processing a data packet in mobile communacation system}

The present invention relates to a method and apparatus for processing a data packet in a mobile communication system, and more particularly, to a method and apparatus for processing a data packet in a state in which a data session with a terminal is released.

The composition of the WCDMA network according to the 3rd Generation Partnership Project (3GPP) standard is largely classified into a mobile station (UE), a radio access network (UTRAN), and a core network.

The UTRAN includes a radio network controller (RNC) for allocating radio resources in a radio access network and delivering data packets to a base station Node B. The RNC acts as an access point to the core network.

The core network is composed of a circuit switched network (CS) and a packet switched network (PS), and the packet switched network is connected to another packet switching network by a SGSN (Serving GPRS Support Node) and a packet switching network that are in charge of managing and supporting packet switching services destined for a wireless access network. It includes a Gateway GPRS Support Node (GGSN) to which it connects.

The SGSN is located between the RNC and the GGSN and forms a tunnel for the Iu-PS section between the RNC and the SGSN and the Gn IP network section between the SGSN and the GGSN for the transmission of data packets in the user plane. And the GTP-U protocol was used.

Recent 3GPP TS 23.060 Release-7 or later discloses a direct tunnel for the direct exchange of data packets between the RNC and the GGSN. However, in the dormant state where the UE does not transmit or receive data for a long time, the radio access bearer is released and in this case, the SGSN receives the data packet from the GGSN, but the data packet received during the reactivation of the data session is RNC. There is a problem that cannot be conveyed to.

An object of the present invention is to provide a method and apparatus for delivering a data packet for a dormant terminal to an RNC even when using a direct tunnel between a GGSN and an RNC.

According to an aspect of the present invention, there is provided a method of processing a data packet in a mobile communication system, wherein a downlink data packet is a packet switched support node (SGSN) destined for a dormant terminal in which a data session is released. Receiving from the packet gateway support node; And transmitting the downlink data packet to the packet gateway support node so that the downlink data packet is transmitted to the radio network controller through the direct tunnel when the direct tunnel is formed between the packet gateway support node and the radio network controller.

Packet switching support node according to an embodiment of the present invention for achieving the above technical problem is a request unit for transmitting a session setting information for requesting to establish a direct tunnel with a radio network controller to the packet gateway support node (GGSN); And a transmitter configured to upwardly transmit the downlink data packet to the packet gateway support node so that the downlink data packet received while the data session with respect to the terminal is released to the wireless network controller through a direct tunnel.

Packet gateway support node according to an embodiment of the present invention for achieving the above technical problem, the tunnel forming unit for forming a direct tunnel for directly transmitting and receiving data packets to a radio network controller (RNC) connected to the packet switching support node; A receiving unit for receiving a downlink data packet for the terminal transmitted to the packet switching support node in a state in which the data session for the terminal is released; And a transmitter configured to directly transmit the returned downlink data packet to the radio network controller through the direct tunnel.

According to an embodiment of the present invention, since the downlink data packet for the dormant terminal received by the SGSN while the data session is released to the terminal can be delivered to the RNC through a direct tunnel between the GGSN and the RNC network activation (Reactivation) In addition, the GGSN can recognize that the data packet returned from the SGSN is received while the data session is released, thereby enabling accurate data packet processing.

1 illustrates a mobile communication system that does not use a direct tunnel.
2A illustrates a mobile communication system using a direct tunnel.
2B is a diagram illustrating a state in which a mobile communication system using a direct tunnel releases a data session of a terminal.
3 is a flowchart illustrating a data packet processing method of a mobile communication system according to an embodiment of the present invention.
4 is a diagram illustrating a packet switching support node according to an embodiment of the present invention.
5 is a diagram illustrating a packet gateway support node according to an embodiment of the present invention.
6 illustrates a header of a downlink data packet according to an embodiment of the present invention.

The following merely illustrates the principles of the invention. Thus, those skilled in the art will be able to devise various apparatuses which, although not explicitly described or shown herein, embody the principles of the invention and are included in the concept and scope of the invention. Furthermore, all of the conditional terms and embodiments listed herein are, in principle, intended only for the purpose of enabling understanding of the concepts of the present invention, and are not intended to be limiting in any way to the specifically listed embodiments and conditions . It is also to be understood that the detailed description, as well as the principles, aspects and embodiments of the invention, as well as specific embodiments thereof, are intended to cover structural and functional equivalents thereof. In addition, these equivalents should be understood to include not only equivalents now known, but also equivalents to be developed in the future, that is, all devices invented to perform the same function regardless of structure.

The above objects, features and advantages will become more apparent from the following detailed description in conjunction with the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

On the other hand, when an element is referred to as "including " an element, it does not exclude other elements unless specifically stated to the contrary.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

When defining terms used in the following description, 'UE (User Equipment)' is a mobile terminal, 'Node B' is a base station, 'RNC (Radio Network Controller)' is a wireless network controller, 'SGSN (Serving GPRS Support Node)' Is a packet switched support node, 'GGSN (Gate GPRS Support Node)' is a packet gateway support node, and 'PDN (Public Data Network)' is used to mean a public data network.

1 illustrates a mobile communication system that does not use a direct tunnel.

Referring to FIG. 1, a mobile communication system using no direct tunnel is provided through a first tunnel 101 between the SGSN 100 and the RNC 110 and a second tunnel 102 between the SGSN 100 and the GGSN 120. Send and receive data packets.

The order in which the downlink data packet received by the GGSN 120 is transmitted from an external packet switching network such as the Internet network is GGSN 120-> second tunnel 102-> SGSN 100-> first tunnel 101- > Through the order of RNC 110. Here, the first tunnel and the second tunnel transmit and receive data packets using the GTP-U protocol.

The signaling of the control plane between the SGSN 100 and the GGSN 120 uses the GTP-C protocol. The SGSN 100 uses the GTP-C protocol to establish a data session with the GGSN 120, that is, activate or release a PDP context, and perform control such as QoS (Quality of Service) configuration. .

Signaling between the SGSN 100 and the RNC 110 uses the Radio Access Network Protocol (RANAP) protocol. The SGSN 100 manages radio resources using the RANAP protocol between the RNCs 110.

For example, the SGSN 100 manages congestion control or error recovery control of the overall Iu interface, paging of a specific terminal, or setting, modifying, and releasing a radio access bearer (RAB).

On the other hand, if the terminal (UE, not shown) connected through the RNC 110 and the base station (Node B, not shown) does not transmit and receive data packets for a predetermined time, the session first tunnel 101 of the dormant terminal for efficient resource management Release it.

If data such as a push message from the core network to the dormant terminal occurs, the SGSN resets the first tunnel 101 to reactivate the data session. The push message is then sent to the RNC 110 via the resumed session.

2A illustrates a mobile communication system using a direct tunnel.

Referring to FIG. 2A, the SGSN 200a of the mobile communication system using the direct tunnel uses the same signaling protocols (RANAP and GTP-C) as the mobile communication system using the direct tunnel.

However, unlike FIG. 1, there is a direct tunnel 201a that directly transmits and receives data packets using the GTP-U protocol between the GGSN 220a and the RNC 210a. The setting of the direct tunnel 201a is determined by the SGSN 200a, and data packets are transmitted and received through the direct tunnel 201a without passing through the SGSN 200a.

On the other hand, RANAP signaling uses an Asynchronous Transfer Mode (ATM) method, and the direct tunnel 201a uses an Internet Protocol (IP) interface. The signaling of the control area and the data of the user area use different protocols, and the RNC 210a operates in an ATM / IP hybrid scheme.

2B is a diagram illustrating a state in which a mobile communication system using a direct tunnel releases a data session of a terminal.

Referring to FIG. 2B, the direct tunnel 201a of FIG. 2A is released. If the terminal (not shown) does not transmit or receive data for a predetermined time, the SGSN 200b transmits a PDP context setting for releasing the direct tunnel 201a to the GGSN 220b, thereby releasing the data session of the terminal.

However, even when the direct tunnel 201a is released, the SGSN 200b may transmit and receive data packets with the GGSN 220 through the GPRS tunnel 201b using the GTP-U protocol.

In this case, when downlink traffic is generated from the core network, the corresponding data packet is delivered to the SGSN 200b through the GPRS tunnel 201b. The SGSN 200 receiving the downlink data packet calls the terminal to terminate the dormant state and reconfigures the direct tunnel 201a through the radio access bearer setup.

That is, even if the data session is resumed, the downlink data packet received by the SGSN 200b does not have a path to be delivered to the RNC 210b, and thus the data packet is lost.

3 is a flowchart illustrating a data packet processing method of a mobile communication system according to an embodiment of the present invention.

Referring to FIG. 3, the mobile communication system includes a UE 370, an RNC 375, an SGSN 380, a GGSN 385, and a PDN 390.

Here, it is assumed that the UE 370 is in an idle state, and the SGSN 380 releases a data session for the UE 370. That is, the direct tunnel between the GGSN 385 and the RNC 385 is released, which is referred to FIG. 2B.

First, the GGSN 385 receives a downlink data packet destined for the UE 370 from the PDN 390 (S305).

The GGSN 385 receives the data packet from the PDN 390 for convenience of description and may receive all general downlink data packets generated from other nodes of the core network.

The GGSN 385 transmits the received downlink data packet to the SGSN 380 through the GPRS tunnel 201b (S310). GPRS tunnel 201b uses the GTP-U protocol.

When the SGSN 380 receives the downlink data packet from the GGSN 385, the SGSN 380 calls the UE 370 in which the data session is released (S315). Calling the SGSN 380 UE 370 is to end the dormant state and reactivate the data session.

The UE 370 transmits a paging response to the SGSN 380 in response to the call of the SGSN 380 (S320).

When the SGSN 380 receives the call response message from the UE 370, the SGSN 380 requests the RNC 375 to establish a radio access bearer (RAB Assignment Request) (S325).

Here, the request for setting the radio access bearer is information for forming a direct tunnel, and includes IP address and Tunnel Endpoint IDentifier (TEID) information of the GGSN 385.

When the direct tunnel is formed in the future, the RNC 375 may directly transmit an uplink data packet from the UE 370 to the GGSN 385 using the received address information and the tunnel terminator of the data area of the GGSN 385.

When the RNC 375 receives the radio access bearer setup request, the RNC 375 sets up the UE 370 and the radio bearer (S330).

In the radio bearer setup process, the RNC 375 requests the UE 370 to configure a radio bearer, and then receives a radio bearer setup complete message from the UE 370.

When the radio bearer setup is completed, the RNC 375 transmits a radio access bearer setup complete (RAB Assignment Response) message to the SGSN 380 (S335).

The radio access bearer setup complete message includes an IP address and a tunnel termination identifier (TEID) of the data area of the RNC 375.

When the direct tunnel is formed in the future, the GGSN 385 sends the downlink data packet from the PDN 390 to the RNC 375 by using the IP address and the tunnel termination identifier (TEID) of the data area of the RNC 375. You can send it directly.

The SGSN 380 inquires whether the RNC 375 operates as an ATM / IP hybrid interface (S340).

In other words, the SGSN 380 confirms that the RNC 375 operates the ATM scheme and the IP scheme simultaneously without using the all IP interface or the all ATM interface.

In the case where the direct tunnel describes ATM / IP hybrid operation, the control area signaling between the RNC 375 and the SGSN 380 is an ATM method, and packet transmission / reception of the data area between the RNC 375 and the GGSN 385 is performed. It means that it is operated by IP interface.

The SGSN 380 may know in advance whether the RNC 375 operates as an ATM / IP hybrid even before the direct tunnel is formed. The reason is that the SGSN 380 may determine the RNC based on the RNC IDentifier (RNC ID) information. This is because the subject decides whether or not to apply a direct tunnel to (375).

Accordingly, the request for establishing a radio access bearer transmitted to the RNC 375 in step S325 is based on the assumption that the SGSN 380 decides to apply a direct tunnel to the RNC 375.

The SGSN 380 may inquire about the operation of the ATM / IP hybrid interface of the RNC 375 by referring to the RNC-ID of the RNC 375 or configuration data set by the SGSN 380.

Therefore, the step of SGSN 380 to query the operation of the ATM / IP hybrid interface does not necessarily need to be located in the current S340, it is a matter that can be inquired in any of steps S305 to S335, but the inquiry in step S340 is only It is for convenience of explanation.

The querying of the ATM / IP hybrid interface operation may be performed at any time before the step S355 in which the SGSN 380 described later transmits the downlink data packet to the GGSN 385.

The GGSN 385 completes the formation of a direct tunnel of the data area with the RNC 375 to resume the data session of the UE 370 (S345).

In more detail, first, the GGSN 385 receives a PDP Context Update request from the SGSN 380. The PDP Context Update request includes data area address information of the RNC 375 received from the RNC 375, tunnel terminal identifier information, and tag (DT = 1) information indicating direct tunnel activation. The GGSN 385 updates the PDP context to complete the formation of the direct tunnel with the RNC 375 and transmits a message informing the SGSN 380 that the formation is completed.

The SGSN 380 records in the header of the downlink data packet received in step S310 an indication and data size indicating that the data session of the UE 370 was released at the time of receiving the data packet (S350).

The data packet is transmitted and received through the GTP-U protocol. Since the GTP-U protocol allows for private extension in the header, a corresponding mark is added to the private extension area. In addition, the data volume information of the received data packet may be recorded as well as an indication that the data session has been released.

For a detailed embodiment of applying the GTP-U protocol to the header, see FIG. 6.

On the other hand, recording the marker in the header in step S350 can be carried out by changing to any step of S315 to S345. That is, before any transmission step of S355 described below, the marker may be recorded in the header at any step, and it is exemplified that what is illustrated as being performed at step S350 is for convenience of description.

If the SGSN 380 confirms that the ATM / IP hybrid interface is operated by the RNC 375, the SGSN 380 transmits the downlink data packet received in the state in which the data session of the UE 370 is released to the GGSN 385 (S355).

The SGSN 380 transmits the downlink data packet after the direct tunnel formation of the GGSN 385 is completed. This is because when the SGSN 380 transmits the downlink data packet to the GGSN 385 before the direct tunnel is formed, the GGSN 385 may send the data packet back to the SGSN 380.

The GGSN 385 confirms the information and the mark recorded in the header of the data packet received from the SGSN 380 (S360).

Since the received data packet is the UE 370 as a destination, it can be confirmed that the packet is transmitted to the UE 370 even if the marker does not exist, but the data packet for the UE 370 is released through the marker. It can be confirmed that the packet is received in the state.

Accordingly, when the GGSN 385 receives a plurality of downlink data packets for the UE 370 from the PDN 390 and the SGSN 380, the GGSN 385 may preferentially transmit a data packet marked with a header.

Meanwhile, the GGSN 385 may discard the data packet when the data size information recorded in the header of the data packet does not satisfy the preset data size criterion. For example, when the GGSN 385 is set to transmit only when the downlink data packet for the terminal is less than or equal to 1 MB, the transmission information is determined by referring to the information of the header of the downlink data packet returned from the SGSN 380.

The GGSN 385 directly transmits the data packet to the RNC 375 through the direct tunnel when the mark and the data size information recorded in the header of the data packet received from the SGSN 380 are confirmed (S365).

Even if the direct tunnel is resumed, since the downlink data packet for the dormant terminal is delivered to the RNC 375, the problem of the conventional direct tunnel can be solved.

4 is a diagram illustrating a packet switching support node according to an embodiment of the present invention.

Referring to FIG. 4, the packet switching support node 400 includes a requesting unit 410, a receiving unit 420, a transmitting unit 430, a recording unit 440, and an inquiry unit 450.

The requesting unit 410 and the receiving unit 420 perform signaling of the GGSN 460 and the control region using the GTP-C protocol, and the transmitting unit 430 sends data to the GGSN 460 using the GTP-U protocol. Send the packet.

Meanwhile, the packet switched support node 400 receives the data packet using the GTP-U protocol from the first interface (not shown) and the GGSN 460 for control region signaling using the RNC 470 and the RANAP protocol. It may further include a second interface (not shown) for.

It is assumed that the packet switched support node 400 receives a downlink data packet from the GGSN 460 through a second interface (not shown) while releasing a data session for a terminal (not shown).

The receiver 420 receives a GSNN and a tunnel termination identifier of a user area and a control area of the GGSN 460 from the GGSN 460. The GSN address generally means an IP address, and the tunnel termination identifier refers to identification information for distinguishing the end point of the GTP tunnel from the end point of another GTP tunnel.

The requesting unit 410 transmits a PDP context update message to the GGSN 460 to instruct the GGSN 460 to form a direct tunnel. The PDP context updata message includes the user area GSN address and tunnel termination identifier of the RNC 470, a tag indicating direct tunnel activation (DT = 1), the control area GSN address and tunnel termination identifier of the packet switched support node 400. do.

The GGSN 460 completes the formation of the direct tunnel based on the PDP context update message and transmits the PDP context response message. The PDP context response is received by the receiver 420.

The recorder 440 records in the header of the downlink data packet received from the GGSN 460, the size of the marker and the size of the data packet indicating that the data session of the terminal has been released when the data packet is received. An embodiment of the header of the downlink data packet is shown in FIG. 6.

The inquiry unit 450 inquires whether the RNC 470 operates as an ATM / IP hybrid interface. In other words, the inquiry unit 450 confirms that the RNC 470 operates the ATM method and the IP method at the same time instead of operating only the all IP interface or the all ATM interface.

When direct tunnels describe ATM / IP hybrid operation on the premise of formation, control area signaling between the RNC 470 and the packet switched support node 400 is an ATM method, and the data area between the RNC 470 and the GGSN 460 is controlled. Packet transmission and reception means that the IP interface is operating.

The inquiry unit 450 may know in advance whether the RNC 470 is operated as an ATM / IP hybrid even before the direct tunnel is formed. The reason for this is that the packet exchange support node 400 receives RNC-ID (RNC IDentifier) information. This is because it is a subject that decides whether or not to apply a direct tunnel to the corresponding RNC 470 based on this.

The query unit 450 may query the operation of the ATM / IP hybrid interface of the RNC 470 by referring to the RNC-ID of the RNC 470 or configuration data set by the RNC 470.

The transmitter 430 transmits the downlink data packet to the GGSN 460 when the inquiry unit 450 confirms the operation of the ATM / IP hybrid interface of the RNC 470.

The transmitting unit 430 may transmit the downlink data packet after the GGSN 460 completes the formation of the direct tunnel. This is because when the transmitter 430 transmits the downlink data packet to the GGSN 385 before the direct tunnel is formed, the GGSN 460 may carry the corresponding data packet.

5 is a diagram illustrating a packet gateway support node according to an embodiment of the present invention.

Referring to FIG. 5, the packet gateway support node 500 includes a tunnel forming unit 510, a packet checking unit 520, a transmitting unit 530, and a receiving unit 540.

The tunnel forming unit 510 forms a direct tunnel of the data area with the RNC 506 through signaling through the SGSN 550 and the GTP-C protocol. That is, the tunnel forming unit 510 receives the PDP context update and transmits the PDP context response to the SGSN 550.

The receiving unit 540 receives the downlink data packet for the dormant terminal transmitted from the SGSN 550 to the SGSN 550 while the data session for the terminal is released.

The returned header of the downlink data packet includes a mark indicating that the data session is released to the terminal and size information of the downlink data packet, which is recorded by the SGSN 550.

The packet checking unit 520 confirms the mark and the data size recorded in the header of the data packet received by the receiving unit. That is, the packet checking unit determines whether to transmit the downlink data packet to the RNC 560 by checking the corresponding mark and data size.

If there is no mark or the data size is outside the predetermined standard set by the mobile communication system administrator, the downlink data packet is discarded.

When the packet checking unit 520 decides to transmit the downlink data packet, the transmitter 530 transmits the downlink data packet to the RNC 506 using the direct tunnel formed by the tunnel forming unit 510.

The present invention can also be embodied as computer-readable codes on a computer-readable recording medium. A computer-readable recording medium includes all kinds of recording apparatuses in which data that can be read by a computer system is stored. Examples of the computer-readable recording medium include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage, and the like. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

Claims (11)

In a mobile communication system in which a packet switching support node (SGSN) supports packet exchange between a packet gateway support node (GGSN) and a radio network controller (RNC), the packet switching support node (SGSN) includes:
Receiving, from the packet gateway support node, a downlink data packet destined for an idle terminal whose data session is released;
Forwarding the downlink data packet to the packet gateway support node such that the downlink data packet is transmitted to the radio network controller through the direct tunnel when a direct tunnel is formed between the packet gateway support node and the radio network controller. And a data packet processing method. The method of claim 1, wherein the uplink transmission step,
Recording an indication in the header of the downlink data packet indicating that the downlink data packet was received in a released state of a data session; And
And transmitting the downlink data packet recorded with the mark to the packet gateway support node. The method of claim 2, wherein the packet gateway support node,
Checking the mark recorded in the downlink data packet received from the packet switched support node; And
And transmitting the downlink data packet through the direct tunnel to the radio network controller when the marking is confirmed. The method of claim 1,
Prior to the uplink transmission, the packet switched support node operates the control area signaling of the radio network controller in an asynchronous transfer mode based on an identifier (RNC-ID) of the radio network controller. Inquiring whether the data area transmission and reception of the wireless network controller is operating as an IP (Internet Protocol) interface;
In the uplink transmission step, the downlink data packet processing method is characterized in that for transmitting the downlink data packet when it is confirmed that each of the asynchronous transmission mode and the IP interface is operated. The method of claim 1,
Before the uplink transmission step, transmitting, by the packet gateway support node, its own address information and a tunnel endpoint identifier (TEID) to the packet switched support node to form the direct tunnel;
In the uplink transmission step, the downlink data packet is transmitted based on the address information and the tunnel endpoint identifier information of the packet gateway support node. In a packet switching support node (SGSN) that supports packet exchange between a radio network controller (RNC) and a packet gateway support node (GGSN),
A request unit for transmitting session establishment information to the packet gateway support node (GGSN) requesting to establish a direct tunnel with the radio network controller; And
And a transmitter configured to upwardly transmit the downlink data packet to the packet gateway support node so that the downlink data packet received in the state of releasing a data session with the terminal is transmitted to the radio network controller through the direct tunnel. Packet-switched support node. The method according to claim 6,
And a recording unit for recording in the header of the downlink data packet an indication indicating that the downlink data packet has been received in the released state of the data session.
And the transmitting unit transmits the downlink data packet recorded with the mark to the packet gateway support node. The method according to claim 6,
Based on the identifier (RNC-ID) of the radio network controller, the control area signaling of the radio network controller operates in an asynchronous transfer mode, and the data area transmission and reception of the radio network controller is performed through an IP (Internet Protocol) interface. Inquiry unit for inquiring whether the operation; further includes,
And the transmission unit transmits the downlink data packet when it is confirmed that the transmission unit operates in the asynchronous transmission mode and the IP interface, respectively. The method according to claim 6,
And a receiving unit for receiving the address information and the tunnel endpoint identifier (TEID) of the packet gateway support node.
And the transmitting unit uplinks the downlink data packet based on the received address information and tunnel endpoint identifier information of the received packet gateway support node. In the packet gateway support node (GGSN) connecting the SGSN and an external packet switched network,
A tunnel forming unit for forming a direct tunnel for directly transmitting and receiving data packets to a radio network controller (RNC) connected to the packet switching support node;
A receiving unit for receiving a downlink data packet for the terminal, which has been transmitted to the packet exchange support node while the data session for the terminal is released; And
And a transmission unit for directly transmitting the returned downlink data packet to the wireless network controller through the direct tunnel. The method of claim 10,
The header of the downlink data packet returned includes an indication indicating that the data session for the terminal is released.
And the transmitting unit transmits the downlink data packet to the radio network controller when the marking is confirmed.

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