WO2015060695A1

WO2015060695A1 - Method and apparatus for traffic offloading in wireless communication system

Info

Publication number: WO2015060695A1
Application number: PCT/KR2014/010103
Authority: WO
Inventors: 프랜클린안토니; 박중신; 손영문; 이철기
Original assignee: 삼성전자 주식회사
Priority date: 2013-10-25
Filing date: 2014-10-27
Publication date: 2015-04-30
Also published as: KR20150047801A

Abstract

The present invention relates to a method and apparatus for traffic offloading in a wireless communication system. The method for traffic offloading in an offload management apparatus in a wireless communication system, according to the present invention, comprises the steps of: confirming a bearer-related parameter with respect to a random bearer; confirming the channel state of backhaul of the wireless communication system; and deciding on offloading of the random bearer, on the basis of the confirmed bearer-related parameter and the confirmed channel state of the backhaul.

Description

Method and apparatus for offloading traffic in wireless communication system

FIELD OF THE INVENTION The present invention relates to a wireless communication system, and more particularly, to a method and apparatus for offloading a traffic in a wireless communication system.

In general, mobile communication systems have been developed to provide voice services while guaranteeing user activity. However, mobile communication systems are gradually expanding to not only voice but also data services, and now they have developed to the extent that they can provide high-speed data services. However, in the mobile communication system in which a service is currently provided, a shortage of resources and users demand faster services, and thus, a more advanced mobile communication system is required.

In response to these demands, research on the selective IP traffic offload (SIPTO) mechanism has been actively conducted in recent years. The SIPTO refers to a technology in which an operator offloads traffic to a node such as a home base station (Home (e) NB) without passing the traffic through the core network.

However, according to the current optional SIPTO, it applies only to traffic of Best Effort or non-critical traffic, but not to traffic whose quality of service (QoS) must be guaranteed above a certain level. Do not.

In addition, there are two types of SIPTOs: a SIPTO for a single Packet Data Network (PDN) and a SIPTO for multiple PDNs. In the case of the SIPTO for a single PDN, the offload decision is made at the flow level, and there is a problem that the complexity increases when the offload decision is made at the flow level. In addition, in case of SIPTO for multiple PDNs, the terminal should be instructed to select a specific PDN connection while determining a flow for offloading, but most terminals do not support the above functions.

Therefore, there is a need for a study on how to support SIPTO for all traffic requiring optimal transmission effort and QoS guarantee.

The present invention has been made to solve the above problems, and an object thereof is to provide a method and apparatus for offloading traffic in a wireless communication system.

More specifically, the present invention provides a method and apparatus for mapping at least one bearer to a core network or to a SIPTO according to bearer related parameters and channel conditions for the bearer. The purpose.

In the wireless communication system of the present invention for solving the above problems, the traffic offload method of the offload management apparatus checks the bearer-related parameters for any bearer, the channel status for the backhaul of the wireless communication system And determining whether to offload any bearer based on the identified bearer related parameters and the channel state for the backhaul.

In addition, the offload management apparatus for managing traffic offload in the wireless communication system of the present invention is a backhaul measuring unit for measuring the channel state for the backhaul of the wireless communication system, and bearer-related parameters for any bearer, And an offload manager for checking the channel state of the backhaul of the wireless communication system and determining whether to offload the bearer based on the identified bearer-related parameters and the channel state of the backhaul. .

According to the present invention, it is possible to support SIPTO for all kinds of traffic.

1 is a diagram illustrating a traffic offload method according to an embodiment of the present invention.

2 is a block diagram showing an internal structure of the offload management apparatus 200 according to the embodiment of the present invention.

3 is a flowchart illustrating a process of determining a bearer mapping by the offload management apparatus 200 according to an embodiment of the present invention.

4 is a flowchart illustrating a process of changing bearer mapping according to a change in a backhaul channel state according to an embodiment of the present invention.

FIG. 5 is a flowchart illustrating a process in a case where a change occurs in a bearer parameter due to a change in an operator policy or user subscription information according to an embodiment of the present invention.

FIG. 6A is a flowchart illustrating a process in which bearer related parameters determined by an operator policy are directly set to a bearer according to an embodiment of the present invention. FIG.

FIG. 6B is a flowchart illustrating a process of transmitting bearer related parameters determined by an operator policy to an offload management apparatus according to an embodiment of the present invention. FIG.

7 is a flowchart illustrating a process of delivering the change when a change occurs in a bearer related parameter according to an embodiment of the present invention.

8 is a flowchart illustrating a process of deactivating a bearer according to an embodiment of the present invention.

9 is a flow chart illustrating a process of deactivating a bearer according to one embodiment of the present invention.

10 is a flowchart illustrating a procedure of initiating a bearer modification procedure according to a change of subscriber information according to an embodiment of the present invention.

11 illustrates the differences between the prior art and the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. At this time, it should be noted that the same components in the accompanying drawings are represented by the same reference numerals as possible. In addition, detailed descriptions of well-known functions and configurations that may blur the gist of the present invention will be omitted.

The following describes an improved SIPTO mechanism in which QoS is guaranteed.

As shown in FIG. 1, a wireless communication network according to an embodiment of the present invention includes a terminal 110, a base station 120, a home network 130, a back haul 140, an internet 150, and a core network 160. It may be configured to include).

The terminal 110 may be connected to the base station 120 through a wireless channel. The base station 120 may include both small base stations such as macro base stations, femto or pico base stations. As will be described later, according to an embodiment of the present invention, the base station 120 may be a home base station (Home (e) NB).

Traffic transmitted by the terminal 110 to the network may be delivered to the Internet 150 or the core network 160 via the base station 120 and the backhaul 140. Such a transmission path may be referred to as a general path.

If the channel state such as the backhaul 140 is in a congestion state, the base station 120 transmits the traffic transmitted from the terminal 110 to the home network 130 instead of transferring the traffic transmitted from the terminal 110 to the backhaul 140. This may be referred to as traffic offload.

The operator may determine whether to perform SIPTO for both traffic of Best Effort and traffic for which QoS should be guaranteed in accordance with the implementation of the present invention described below.

To this end, in the embodiment of the present invention, as a factor for determining traffic offload, an operator policy, a session continuity support of the flows, and a current congestion state of the backhaul network congestion in the backhaul network).

The operator policy may be determined by user subscription information, an application type, an application service provider, and the like. The operator may determine whether to offload the bearer based on the above information. In an embodiment of the present invention, the operator policy may be set through a SIPTO flag parameter. If the SIPTO flag is set to Yes (On), the bearer may be set to map to the possible SIPTO.

Session continuity support of a flow may be determined by information such as application type, application provider, and the like. In addition, session continuity support of the flow may be determined by operator policy. According to one embodiment of the invention, any flow may move from any one node to another node via IP tunneling, where the continuity of the session may not be guaranteed if the nodes belong to different anchors. If session continuity is to be guaranteed, session continuity support of the flow may be set to Yes.

The current congestion situation in the backhaul network can be a very important factor for offloading traffic. According to an embodiment of the present invention, the congestion situation of the backhaul network may be measured periodically or aperiodically by the offload management apparatus.

According to one embodiment of the present invention, the improved SIPTO mechanism may be performed in a home base station (Home (e) NB) or the like.

Furthermore, according to one embodiment of the present invention, since the QoS of flows is considered for SIPTO offload determination, it is possible to implement a bearer level offload mechanism. The bearer level offload mechanism can reduce the complexity than conventional packet level or PDN level offload.

2 is a block diagram illustrating an internal structure of the offload management apparatus 200 according to an embodiment of the present invention.

As described above, according to an embodiment of the present invention, the offload management apparatus 200 may be a home base station (H (e) NB).

As shown in FIG. 2, the offload management apparatus 200 according to an embodiment of the present invention may include a backhaul measurement unit 210 and an offload manager 220.

The backhaul measuring unit 210 measures the state of the backhaul periodically or aperiodically. The state of the backhaul may mean a congestion level of the backhaul. Alternatively, the state of the backhaul may mean a QoS level that can be supported according to the state of the current backhaul.

To this end, the backhaul measuring unit 210 may measure end-to-end delay and loss rate. The backhaul measuring unit 210 may determine quality control information (QCI) that can be supported by the backhaul based on the measurement result. As will be described later, the determined QCI may be used as a parameter for determining whether each bearer is mapped to CN or SIPTO.

As described above, the backhaul measurement unit 210 measures the state of the backhaul periodically or aperiodically, and if the current measurement result is different from the previous measurement result, may report it to the offload manager 220. .

The offload manager 220 reports the backhaul measurement result from the backhaul measurement unit 210. The offload manager 220 may receive a measurement result from the backhaul measurement unit 210 periodically or aperiodically, or may request that the backhaul measurement unit 210 measure and report a channel state of the backhaul.

The offload manager 220 may map each bearer to a CN or SIPTO based on operator policy, session continuity support of the flow, and channel state of the backhaul, as described above.

In more detail, the operator policy may be set whether or not the flow is offloaded based on user subscription information. The operator policy may be set through a SIPTO flag in an embodiment of the present invention.

In addition, the session continuity support of the player may be determined by information such as an operator policy, an application type, an application provider, and the like. The continuity support of the flow may be set through a session continuity flag in an embodiment of the present invention.

Conventionally, the bearer is set only by QoS parameters such as QCI, Guaranteed Bitrates (ARP), Guaranteed Bitrates (GBR), Maximum Bit Rate (MBR), and the like. ) May also be set by the Session Continuity Flag. Hereinafter, the SIPTO flag and the session continuity flag may be referred to as bearer related parameters. The bearer related parameter may include conventional QCI information, in addition to a SIPTO flag and a session continuity flag.

For example, conventionally, all flows with the same QCI were assigned to the same bearer. On the other hand, according to an embodiment of the present invention, even if the QCI is the same flow, if the SIPTO flag and the session continuity flag are set differently, each flow may be assigned to a different bearer.

According to an embodiment of the present invention, when the SIPTO flag is set to 1 (or Yes), this may mean that the operator policy has decided to offload the flow through the SIPTO if possible. In addition, when the Session Continuity Flag is set to 1 (or Yes), this may mean that the operator policy has determined that session continuity for the corresponding flow should be guaranteed.

In an embodiment of the present invention, a SIPTO flag and a session continuity flag may be added as additional parameters for forming any bearer, and the offload manager 220 may be based on the parameters. The mapping relationship of bearers can be determined.

An embodiment in which the offload manager 220 maps bearers according to an embodiment of the present invention will be described in detail with reference to Table 1 below.

Table 1

SIPTO Flag	Session Continuity Flag	Bearer QCI is supported by backhaul	Bearer Mapping (SIPTO / CN)
No	*	*	CN
Yes	*	No	CN
Yes	No	Yes	SIPTO
Yes	Yes	Yes	SIPTO / CN

In Table 1, bearers in which the SIPTO flag is set to NO are mapped to CN. This is because the operator policy has determined that the bearer will not be offloaded.

In addition, if the SIPTO flag is set to Yes, but the current state of the backhaul does not guarantee the QCI, the bearer is mapped to the CN. According to an embodiment of the present invention, even if the SIPTO flag is set to 1, the bearer may be offloaded only when the backhaul state guarantees a certain level of quality of service without unloading the bearer unconditionally. have.

In addition, if the SIPTO Flag is set to Yes, the Session Continuity Flag is set to NO, and the current backhaul can guarantee QCI, the bearer may be mapped to the SIPTO. .

In addition, if the SIPTO Flag is set to Yes, the Session Continuity Flag is set to Yes, and the status of the current backhaul can guarantee QCI, then the bearer can guarantee that the backhaul It may be mapped to SIPTO or CN depending on the level of QoS. For example, if a QoS level that can be guaranteed by the backhaul is less than a preset threshold, that bearer can be mapped to a CN. Can be.

As described above, according to an embodiment of the present invention, the offload manager 220 of the offload management apparatus 200 transfers any bearer to either the CN or CIPTO network based on the bearer related parameter and the channel state of the backhaul. You can decide whether to map.

In addition, according to another embodiment of the present invention, the offload manager 220 may determine the bearer mapping relationship according to the QoS current state (level) in the backhaul or mobility support for SIPTO traffic handling.

3 is a flowchart illustrating a process of determining bearer mapping by the offload management apparatus 200 according to an embodiment of the present invention.

First, the offload management apparatus 200 establishes at least one bearer in operation S310. According to an embodiment of the present invention, the bearers may be classified according to at least one of QCI or bearer related parameters. For example, bearers with different QCIs can be distinguished from each other. Further, even if the QCIs are the same, bearers having different bearer related parameters may be distinguished from each other. The bearer related parameter may include at least one of a SIPTO flag or a session continuity flag.

In operation S320, the offload management apparatus 200 determines whether a SIPTO flag is set to On (Yes) among bearer-related parameters for an arbitrary bearer. If the SIPTO flag is not set to On (Yes), the offload management apparatus 200 proceeds to step S350 to map the bearer to CN. In other words, the offload management apparatus 200 does not offload the bearer and maps it to the core network.

On the other hand, if the SIPTO flag is set to On (Yes), the offload management apparatus 200 proceeds to step S330 to determine whether the QCI is supported by the SIPTO. In other words, the offload management apparatus 200 may compare the channel measurement state of the backhaul with the QCI to be guaranteed for the bearer and determine whether the channel state of the backhaul can support the QCI set for the bearer. .

As a result of the determination, if it is not supported, the offload management apparatus 200 proceeds to step S350 to map the bearer to CN. In other words, the offload management apparatus 200 does not offload the bearer and maps it to the core network.

On the other hand, if it is determined that the support, the offload management device 200 proceeds to step S340 to determine whether the mobility support is set to On (Yes). If not set, the offload management apparatus 200 proceeds to step S360 to map the bearer to SIPTO. In other words, the offload management apparatus 200 offloads the bearer.

On the other hand, if set, the offload management apparatus 200 may proceed to step S370 to map the bearer to the SIPTO or CN according to the level of QoS that the backhaul can guarantee. For example, when the QoS level that can be guaranteed by the backhaul is less than a preset threshold, the offload management device 200 may map the bearer to the CN, or the threshold that the QoS level that the backhaul can guarantee is preset. If the value is greater than or equal to the value, the offload management apparatus 200 may map the bearer to the SIPTO.

According to an embodiment of the present invention, the offload management apparatus 200 may continuously monitor a change in QoS level support in the backhaul. When a change in QoS level support is detected in the backhaul, the offload management apparatus 200 may determine whether there is a change in the offload determination for the bearer according to the criteria illustrated in Table 1 above.

There may be two kinds of offload crystal changes. The first is when a bearer mapped to (or determined to be mapped to) a CN changes to being mapped to a SIPTO, and the second is when a bearer mapped to (or determined to be mapped) changes to being mapped to a CN. to be. When the bearer mapped to the SIPTO is mapped to the CN, for example, the channel state of the core network is improved.

If the session continuity flag is set to Off, the bearer may be released.

When bearer mapping is changed from CN to SIPTO, it may be desirable to maintain a bearer mapping state to CN. In the case of IP tunneling, traffic transmission from the P-GW to the home base station may be possible.

The above case is summarized in Table 2 below.

TABLE 2

Session Continuity Flag	Action
Yes	Keep the bearer in CN / IP tunneling the traffic from P-GW to H (e) NB)
No	Initiate Release of bearer

If bearer mapping is changed from SIPTO to CN, it may not be desirable to use IP tunneling between SIPTO and CN because degraded QoS may not be improved in SIPTO. Accordingly, the bearer (traffic) can maintain the bearer mapping state to the SIPTO with degraded QoS. Alternatively, according to an embodiment of the present invention, the bearer may be released.

The above case is summarized in Table 3 below.

TABLE 3

Session Continuity Flag	Action
Yes	Keep the bearer in SIPTO with degraded QoS / Release of bearer which breaks the session
No	Initiate Release of bearer

The operation is described with reference to FIG. 4 as follows.

First, the offload management apparatus 200 determines whether a change is detected in the SIPTO QCI in step S410. If a change is detected, the offload management apparatus 200 starts a determination as to whether it is necessary to change the mapping setting for each bearer in step S420.

To this end, the offload management apparatus 200 evaluates the offload determination in step S430. As a result of the evaluation, if it is determined that a change has occurred in the offload determination in step S440, the offload management apparatus 200 determines whether the session continuity flag is set to Yes (On) in step S450. .

If not set to Yes, the offload management apparatus 200 proceeds to step S460 to release the bearer.

On the other hand, if the Session Continuity Flag is set to Yes, the offload management apparatus 200 proceeds to step S470, and whether the offload decision change is a change from SIPTO to CN or from CN to SIPTO. Determine whether or not.

In the case of a change from SIPTO to CN, the offload management apparatus 200 may proceed to step S480 to maintain the mapping setting to the SIPTO. Alternatively, according to another embodiment of the present invention, the offload management apparatus 200 may release the bearer.

On the other hand, when the change from CN to SIPTO, the offload management apparatus 200 may proceed to step S490 to maintain the mapping setting to the CN.

In operation S495, the offload management apparatus 200 may repeat the above process for the next bearer.

FIG. 5 is a flowchart illustrating a process in a case where a change is made in a bearer parameter due to a change in an operator policy or user subscription information according to an embodiment of the present invention.

Although the bearer mapping relationship may be changed according to the channel state of the backhaul (described in FIG. 4), the bearer mapping relationship may also be changed by changing an operator policy or user subscription information according to an embodiment of the present invention.

The offload management apparatus 200 may monitor the bearer modification matter periodically or aperiodically. The offload decision may be evaluated and maintained or changed according to the monitoring result. This will be described in detail with reference to the flowchart of FIG. 5.

First, the offload management apparatus 200 determines whether a bear modification has occurred for each bearer in operation S510.

When the occurrence is detected, the offload management apparatus 200 starts evaluating the offload determination previously performed in order to determine whether it is necessary to change the offload determination for each bearer in operation S520.

As a result of the evaluation, if it is determined that a change has occurred in the offload determination in step S530, the offload management apparatus 200 determines whether the session continuity flag is set to Yes (On) in step S540. .

If not set to Yes, the offload management apparatus 200 proceeds to step S550 to release the bearer.

On the other hand, if the Session Continuity Flag is set to Yes, the offload management apparatus 200 proceeds to step S560, whether the offload decision change is a change from SIPTO to CN or from CN to SIPTO. Determine whether or not.

In the case of a change from SIPTO to CN, the offload management apparatus 200 may proceed to step S570 to maintain mapping setting to SIPTO. Alternatively, according to another embodiment of the present invention, the offload management apparatus 200 may release the bearer.

On the other hand, when the change from CN to SIPTO, the offload management apparatus 200 may proceed to step S580 to maintain the mapping setting to the CN.

The offload management apparatus 200 may proceed to step S590 to repeat the above process for the next bearer.

FIG. 6A is a flowchart illustrating a process of delivering the parameter so that a bearer may be directly set based on a bearer related parameter determined by an operator policy according to an embodiment of the present invention.

6A, a bearer related parameter including at least one of a SIPTO Flag and a Session Continuity Flag set in the PCRF 650 is transferred to the PDN GW 640.

Then, the PDN GW 640 generates a bearer by including a SIPTO Flag and a Session Continuity Flag parameter as bearer configuration values when initial bearer creation.

In addition, the S-GW 630 and the eNB 610 generate a bearer including a SIPTO Flag and a Session Continuity Flag parameter as bearer setting values when the bearer is generated.

Hereinafter, the flow of FIG. 6A will be described in detail.

First, the application function (AF) 660 may transmit a service notification message to the policy charging and rules function (650 PCRF) 650 in operation S680. Then, the PCRF 650 forwards the IP-CAN session modification message to the PDG GW 640 in step S681. Subsequently, the PCRF 640 may deliver a Policy and Charging Rule Provisioning message to the PDG GW 640 in step S682. The policy and charging rule preparation message may include a bearer related parameter, for example, a SIPTO flag and a session continuity flag.

In operation S683, the PDN GW 640 may transmit a Create Bearer Request message to the Serving GW 630. The bearer creation request message instructs to create a bearer by including a SIPTO Flag and a Session Continuity Flag parameter as a bearer configuration value upon initial bearer creation.

Then, the Serving GW 630 may transmit a Create Bearer Request message to the MME 620 in step S684.

In operation S685, the MME 620 may transmit a bearer setup request message and / or a session management request message to the base station 610.

Then, the base station 610 transmits an RRC connection reconfiguration message to the terminal 600 in step S686. In step S687, the terminal 600 transmits an RRC connection reconfiguration complete message to the base station 610.

Then, the base station 610 transmits a bearer setup response message to the MME 620 in step S688.

Thereafter, the terminal 600 transmits a direct transfer message to the base station 610 in step S689. Then, the base station 610 transmits a session management response message to the MME 620 in step S690. Then, the MME 620 transmits a bearer response message to the Serving GW 630 in step S691.

In operation S692, the serving GW 630 transmits a bearer create response message to the PDN GW 640. Then, the PDN GW 640 forwards the IP-CAN session modification message to the PCRF 650 in step S692.

As can be confirmed through the above process, the PDN GW 640 may generate a bearer including a SIPTO Flag and a Session Continuity Flag parameter as bearer configuration values when initial bearer creation.

FIG. 6B is a flowchart illustrating a process of maintaining a legacy bearer system according to an embodiment of the present invention, and transmitting bearer related parameters determined by an operator policy as a message to an offload management apparatus.

More specifically, FIG. 6 illustrates a process in which bearer related parameters are delivered in a dedicated bearer activation process.

According to an embodiment of the present invention, the offload management apparatus may be a home base station (HeNB) or a base station (eNB).

According to an embodiment of the present invention, the bearer related parameter may include at least one of a SIPTO flag and a session continuity flag. The bearer related parameter may be delivered to the home base station or the base station as additional information during the bearer set up process.

As described below, the bearer related parameters are delivered to a Mobility Management Entity (MME) during bearer activation or modification, and the MME sends the bearer related parameters to a home base station or base station. You can pass it to the offload manager.

While managing mobility, the bearer related parameters may be passed to a target base station.

This will be described in more detail with reference to FIG. 6B.

First, the application function (AF) 660 may transmit a service notification message to the policy charging and rules function 650 in step S605. Then, the PCRF 650 transmits the IP-CAN session modification message to the PDN GW 640 in step S610. Subsequently, the PCRF 650 may deliver a Policy and Charging Rule Provisioning message to the PDG GW 640 in step S615. The policy and charging rule preparation message may include a bearer related parameter, for example, a SIPTO flag and a session continuity flag.

In operation S620, the PDN GW 640 may transmit a Create Bearer Request message to the Serving GW 630. The bearer creation request message may include a SIPTO flag and a session continuity flag.

Then, the Serving GW 630 may transmit a Create Bearer Request message to the MME 620 in step S625. The bearer creation request message may include a SIPTO flag and a session continuity flag.

Then, in step S630, the MME 620 may store the received SIPTO flag and session continuity flag.

In operation S635, the MME 620 may transmit a bearer setup request message and / or a session management request message to the base station 610. The bearer establishment request message or session management request message may include a received SIPTO flag and a session continuity flag.

Then, the base station 610 transmits an RRC connection reconfiguration message to the terminal 600 in step S640. Then, the terminal 600 transmits an RRC connection reconfiguration complete message to the base station 610 in step S645.

Then, the base station 610 transmits a bearer setup response message to the MME 620 in step S650.

Thereafter, the terminal 600 transmits a direct transfer message to the base station 610 in step S655. Then, the base station 610 transmits a session management response message to the MME 620 in step S660. Then, the MME 620 delivers a bearer response message to the Serving GW 630 in step S665.

In operation S670, the Serving GW 630 transmits a bearer create response message to the PDN GW 640. Then, the PDN GW 640 forwards the IP-CAN session modification message to the PCRF 650 in step S675.

As can be seen through the above process, the bearer related parameters may be delivered to the base station 610 including the offload management apparatus through the MME 620 in the dedicated bearer activation process.

As shown below, in the event of a change in bearer related parameters, the PCRF may provide a PCC rule to the updated bearer.

As shown in FIG. 7, an application function (AF) 760 may deliver a service notification message to a policy charging and rules function 750 in step S705. Then, the PCRF 750 transmits the IP-CAN session modification message to the PDG GW 740 in step S710. In step S715, the PCRF 750 may deliver a policy and charging rule provisioning message to the PDG GW 740. The policy and charging rule preparation message may include a bearer related parameter, for example, a SIPTO flag and a session continuity flag.

In operation S720, the PDN GW 740 may transmit a bearer update request message to the Serving GW 730.

Then, the Serving GW 730 may transmit a bearer update request message to the MME 720 in step S725.

Then, in step S730, the MME 720 may transmit a bearer modification request message and / or a session management request message to the base station 710.

Then, the base station 710 transmits an RRC connection reconfiguration message to the terminal 700 in step S735. Then, the terminal 700 transmits an RRC connection reconfiguration complete message to the base station 710 in step S740.

Then, the base station 710 transmits a bearer modify response message to the MME 720 in step S745.

Thereafter, the terminal 700 transmits a direct transfer message to the base station 710 in step S750. Then, the base station 7610 transmits a session management response message to the MME 720 in step S755. Then, the MME 720 transmits a bearer update response (Update Bearer Response) message to the Serving GW 730 in step S760.

In operation S765, the Serving GW 730 transmits a bearer update response message to the PDN GW 740. Then, the PDN GW 740 forwards the IP-CAN session modification message to the PCRF 750 in step S70.

According to an embodiment of the present invention, the PCRF may determine to delete (or release) a bearer due to a change in an operator policy or the like. After a plurality of bearers are formed for the SIPTO or CN, if all flows are moved to the SIPTO / non-SIPTO, other bearers may be deleted using the bearer deactivation procedure.

This will be described in detail with reference to the flowchart of FIG. 8. 8 shows that the PDN GW initiates bearer deactivation.

In step S805, the PCRF 860 may transmit an IP-CAN session modification message to the PDN GW 850. Then, the PGDN GW 850 transmits a bearer deletion request message to the Serving GW 840 in step S810.

Then, the serving GW 840 may transmit a bearer deletion request message to the MME 820 and the SGSN 830, respectively, in steps S815 and S850.

Then, the MME 820 may transmit a Detach Request message to the terminal 800 in step S825. In operation S830, the MME 820 initiates a trigger for reactivation in the ECM-IDLE.

The MME 820 may transmit a bearer deactivation request message to the base station 810 in step S835. Then, the base station 810 transmits an RRC connection reset message to the terminal 800 in step S840, and the terminal 800 transmits an RRC connection reset complete message to the base station 810 in step S845.

Then, the base station 810 may transmit a bearer deactivation response message to the MME 820 in step S850.

Thereafter, the terminal 800 transmits a direct transmission message to the base station 810 in step S855, and the base station 810 transmits an EPS bearer context inactivation acceptance message to the MME 820 in step S860. Thereafter, the terminal 800 may transmit a connection accept message to the MME 820 in step S865.

The MME 820 may transmit a bearer deletion response message to the Serving GW 840 in operation S870, and the SGSN 830 may transmit a bearer deletion response message to the Serving GW 840 in operation S875.

Then, in step S880, the Serving GW 840 transmits a bearer deletion response message to the PDN GW 850, and the PDN GW 850 transmits an IP-CAN session modification message to the PCRF 860 in step S8850.

In step S890, the terminal 800 may release the signaling connection through signaling between the base station 810 and the MME 820.

9 is a flowchart illustrating a process of deactivating a bearer according to an embodiment of the present invention. 9 is a flow chart for how the MME initiates bearer deactivation.

When determining whether to offload, if any bearer should be released, the base station will trigger the release of the bearer, the bearer release may be initiated by the MME.

First, the terminal 900 may transmit a radio bearer release message to the base station 900 in step S905. Then, the base station 910 may transmit a bearer release indicator to the MME 920 in step S910. Then, the MME 920 may transmit a bearer delete command to the Serving GW 930 in operation S915.

Then, the Serving GW 930 may transmit a bearer delete command to the PDN GW 940 in operation S920, and the PDN GW 940 exchanges an IP-CAN session modification message with the PCRF 950 in operation S925. .

In operation S930, the PDN GW 940 transmits a bearer deletion request message to the Serving GW 930. Then, the Serving GW 930 transmits a bearer deletion request message to the MME 920 in step S935. Then, a bearer deactivation procedure may be performed in step S940.

In operation S945, the MME 920 may transmit a bearer deletion response message to the Serving GW 930, and the Serving GW 930 may transmit a bearer deletion response message to the PDN GW 940 in operation S950.

10 is a flowchart illustrating a procedure of starting a bearer modification procedure according to a change of subscriber information according to an embodiment of the present invention.

First, a home subscriber server (HSS) transmits a subscriber data insertion message to the MME 1030 in step S1005. Then, the MME delivers the subscriber data insertion confirmation message to the HSS 1070 in step S1010.

Thereafter, the MME 1030 updates the context information of the UE in step S1015, and transmits a bearer modification command message to the Serving GW 1040 in step S1020. Then, the Serving GW 1040 transmits a bearer modification command message to the PDN GW 1050 in step S1025. Then, the PDN GW 1050 exchanges the IP-CAN session modification message with the PCRF 1060 in step S1030.

Thereafter, the PCRF 1060 transmits the policy and charging rule preparation message to the PDN GW 1050 in step S1035. The policy and charging rule preparation message may include a SIPTO flag and a session continuity flag according to an embodiment of the present invention. In operation S1040, the PDN GW 1050 may deliver a bearer update request message to the Serving GW 1040.

Then, the bearer modification procedure is performed in step S1045.

The Serving GW 1040 may transmit a bearer update response message to the PDN GW 1050 in step S1050, and the PDN GW 1050 may transmit a confirmation message to the PRCF 1060 in step S1055.

11 is a diagram showing the difference between the prior art and the present invention.

First, FIG. 11A is a diagram showing a SIPTO according to the prior art. 11A illustrates a SIPTO situation for multiple PDNs.

As shown in FIG. 11A, the plurality of

IP sessions

1100 and 1110 may each include at least one EPS bearer. The initially created bearers are called

default EPS bearers

1101 and 1111, and the bearers created afterwards are called dedicated EPS bearers.

According to the prior art, the quality of service (QoS) of each bearer is different. In addition, whether each bearer is mapped to the core network or to the L-GW is predetermined at the time of bearer creation, and bearers included in the same IP session are all mapped to the core network or the L-GW in the same manner. For example, all

bearers

1101, 1102, 1103, 1104 belonging to IP session 1100 are all mapped to the core network, and all

bearers

1111, 1112, 1113, 1114 belonging to IP session 111 are L. Mapped to GW. In this case, the bearer 1102 belonging to the IP thin line 1100 may not be mapped to the L-GW.

11B is a diagram illustrating a SIPTO according to an embodiment of the present invention.

According to an embodiment of the present invention, the QoS value of each bearer may be the same. In other words, in the embodiment of the present invention, the element determining the bearer's characteristics may further include bearer related parameters (SIPTO Flag, Session Continuity Flag, etc.) in addition to QoS.

In addition, according to an embodiment of the present invention, each bearer included in the same IP session may be selectively mapped to the core network or the L-GW by factors such as bearer related parameters. For example, even though bearers belonging to the same IP session 1120, the bearer 1121 and the bearer 1122 may be mapped to the core network, and the bearer 1122 and the bearer 1124 may be mapped to the L-GW. .

According to the present invention described above, it is possible to support SIPTO for all kinds of traffic.

The embodiments of the present invention disclosed in the specification and the drawings are only specific examples to easily explain the technical contents of the present invention and aid the understanding of the present invention, and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention can be carried out in addition to the embodiments disclosed herein.

Claims

A traffic offload method of an offload management apparatus in a wireless communication system,

Identifying bearer related parameters for any bearer;

Confirming a channel state for a backhaul of the wireless communication system; And

Determining whether to offload any of the bearers based on the identified bearer related parameters and the channel status for the backhaul.
The method of claim 1, wherein the bearer related parameters are:

And at least one of a Selective IP Traffic Offload (SIPTO) flag and a Session Continuity flag that determine whether to offload the bearer.
The method of claim 1, wherein the checking of the channel state comprises:

And determining at least one of a degree of congestion for the backhaul or a quality of service that can be supported according to the state of the backhaul.
The method of claim 2,

Wherein the SIPTO flag and session continuity flag support are set based on at least one of user subscription information, operator policy, application type, or application provider.
The method of claim 1, wherein the determining step,

If Quality Control Information (QCI) for any bearer is not supported by the channel state for the identified backhaul,

Traffic offloading method characterized in that the mapping to the core network (Core Network, CN) without offloading the bearer.
The method of claim 2, wherein the determining step,

Detecting that a channel state for the backhaul has changed;

Determining whether there is a change in offload determination for any bearer due to the channel state for the changed backhaul; And

If there is a change, further comprising maintaining an offload decision for the any bearer or releasing the bearer according to the Session Continuity flag and offload decision change type. Traffic offload method, characterized in that.
The method of claim 2, wherein the determining step,

Detecting that a modification to any bearer has occurred due to a change in an operator policy or user subscription information;

Determining whether there is a change in offload determination for the any bearer due to the modification to the any bearer; And

If there is a change, further comprising maintaining an offload decision for the any bearer or releasing the bearer according to the Session Continuity flag and offload decision change type. Traffic offload method, characterized in that.
An offload management apparatus for managing traffic offload in a wireless communication system,

A backhaul measuring unit measuring a channel state of the backhaul of the wireless communication system; And

Bearer related parameters for any bearer, confirm channel state for backhaul of the wireless communication system, and whether to offload for any bearer based on the identified bearer related parameters and channel state for backhaul And an offload manager for determining.
The method of claim 8, wherein the bearer-related parameters,

And at least one of a Selective IP Traffic Offload (SIPTO) flag and a Session Continuity flag that determine whether to offload the bearer.
The method of claim 8, wherein the backhaul measuring unit,

And at least one of a degree of congestion for the backhaul or a quality of service that can be supported according to the state of the backhaul.
The method of claim 9,

And the SIPTO flag and session continuity flag support are set based on at least one of user subscription information, an operator policy, an application type, or an application provider.
The method of claim 8, wherein the offload manager,

If Quality Control Information (QCI) for any bearer is not supported by the channel state for the identified backhaul,

Offload management apparatus characterized in that the control to map to the core network (Core Network, CN) without offloading the bearer.
The method of claim 9, wherein the offload manager,

When detecting that the channel state for the backhaul has changed, it is determined whether there is a change in the offload decision for the bearer due to the changed channel state for the backhaul, and if there is a change, the or session continuity Continuity) and control to maintain an offload decision for the bearer or release the bearer according to a flag and offload decision change type.
The method of claim 9, wherein the offload manager,

If it is detected that a modification to any bearer has occurred due to a change in an operator policy or user subscription information, whether there is a change in the offload decision for any bearer due to the modification to any bearer. Determine and, if there is a change, maintain the offload decision for the bearer or release the bearer according to the Session Continuity flag and offload decision change type. Off-road management apparatus, characterized in that.