KR20150047801A - Method and apparatus for offload traffic in wireless communication system - Google Patents

Abstract

The present invention relates to a method and apparatus for traffic offload in a wireless communications system, having steps of: identifying a parameter related to bearer of arbitrary bearer; identifying channel state of a back hole for the wireless communications system; and deciding an offload of the arbitrary bearer based on the parameter related to an identified bearer and the channel state of the back hole.

Description

TECHNICAL FIELD [0001] The present invention relates to a method and apparatus for offloading traffic in a wireless communication system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless communication system, and more particularly, to a traffic offload method and apparatus in a wireless communication system.

Generally, a mobile communication system has been developed to provide voice service while ensuring the user's activity. However, the mobile communication system is gradually expanding not only to voice but also to data service, and now it has developed to the extent of providing high-speed data service. However, in a mobile communication system in which a service is currently provided, a lack of resources and users demand higher speed services, and therefore, a more advanced mobile communication system is required.

Recently, selective IP traffic offload (SIPTO) mechanism has been actively researched. The SIPTO refers to a technique in which an operator offloads traffic to a node such as a home base station (Home (e) NB) without going through a core network.

However, according to the present selective SIPTO, it is applied only to the traffic of the best effort or the non-critical traffic, and is not applied to the traffic that needs to guarantee a certain level of quality of service (QoS) Do not.

There are also two types of SIPTOs: SIPTO for a single PDN (Packet Data Network) and SIPTO for multiple PDNs. In the case of SIPTO for a single PDN, the offload determination is performed at the flow level, and when the offload determination is made at the flow level, the complexity increases. In addition, in the case of SIPTO for multiple PDNs, while determining the flow for offload, the terminal must be instructed to select a specific PDN connection, but most terminals do not currently support this function.

Therefore, it is necessary to study how to support SIPTO for all traffic that requires the best transmission effort and QoS guarantee.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and apparatus for offloading traffic in a wireless communication system.

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

In order to solve the above problems, a method of offloading traffic of an offload management apparatus in a wireless communication system of the present invention comprises: checking bearer-related parameters for an arbitrary bearer; checking a channel state of a backhaul of the wireless communication system; Determining whether the bearer is offloaded based on the identified bearer-related parameters and the channel state for the backhaul.

In addition, an off-load management apparatus for managing a traffic offload in a wireless communication system of the present invention includes: a backhaul measurement unit for measuring a channel state of a backhaul of the wireless communication system; and a bearer-related parameter for an arbitrary bearer, And an offload manager for determining a channel state for a backhaul of the wireless communication system and for determining whether to offload the arbitrary bearer based on the confirmed bearer-related parameter and the channel state for the backhaul .

According to the present invention, SIPTO can be supported for all kinds of traffic.

1 illustrates a traffic offloading method in accordance with an embodiment of the present invention.
2 is a block diagram showing an internal structure of an offload management device 200 according to an embodiment of the present invention.
3 is a flow chart showing a process by which the offload management device 200 determines bearer mapping according to an embodiment of the present invention.
4 is a flowchart illustrating a process of changing a bearer mapping according to a change in a state of a backhaul channel, according to an embodiment of the present invention;
5 is a flow diagram illustrating a process when a bearer parameter change occurs due to an operator policy or user subscription information change according to an embodiment of the present invention;
FIG. 6A is a flowchart showing a process in which a bearer-related parameter determined by an operator policy according to an embodiment of the present invention is transmitted to a bearer; FIG.
FIG. 6B is a flowchart showing a process in which a bearer-related parameter determined by an operator policy is transmitted to an offload management apparatus according to an embodiment of the present invention; FIG.
FIG. 7 is a flowchart showing a process of delivering the change when a bearer-related parameter is changed according to an embodiment of the present invention; FIG.
FIG. 8 is a flowchart illustrating a process of deactivating a bearer according to an embodiment of the present invention. FIG.
Figure 9 is a flow diagram illustrating a process of deactivating a bearer in accordance with an embodiment of the present invention.
10 is a flowchart showing a process of starting a bearer modification procedure according to subscriber information change according to an embodiment of the present invention;
11 is a diagram showing the differences between the prior art and the present invention;

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that, in the drawings, the same components are denoted by the same reference symbols as possible. Further, the detailed description of well-known functions and constructions that may obscure the gist of the present invention will be omitted.

Hereinafter, an improved SIPTO mechanism with guaranteed QoS will be described.

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

1, a wireless communication network according to an exemplary embodiment of the present invention includes a terminal 110, a base station 120, a home network 130, a backhaul 140, an Internet 150, a core network 160 ). ≪ / RTI >

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

The traffic transmitted to the network by the terminal 110 may be transmitted to the Internet 150 or the core network 160 via the base station 120 and the backhaul 140. [ This transmission path can be referred to as a general path.

If the channel state of the backhaul 140 is in a congestion state, the base station 120 may transmit the traffic transmitted from the terminal 110 to the home network 130 instead of delivering the traffic to the backhaul 140 And can be referred to as traffic offsets.

The operator can determine whether to perform SIPTO for both the best effort traffic and the traffic for which QoS is to be ensured according to the practice of the invention to be described below.

For this purpose, in the embodiment of the present invention, operator factors such as operator policy, session continuity support of the flows, and the current level of the backhaul network congestion in the backhaul network.

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

The session continuity support of a flow can be determined by information such as an application type, an application provider, and the like. The session continuity support of the flow may also be determined by an operator policy. According to an embodiment of the present invention, any flow can be moved from any one node to another node through IP tunneling, and the continuity of the session may not be ensured if the nodes belong to different anchors. If the continuity of the session is to be ensured, the session continuity support of the above flow can be set to Yes.

The current congestion situation in the backhaul network can be a very important factor for offloading traffic. According to one embodiment of the present invention, the congestion situation of the backhaul network can be measured periodically or non-periodically by the offload management device.

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

Also, according to one embodiment of the present invention, the bearer level offload mechanism can be implemented since the QoS of the flows is considered for SIPTO offload determination. The bearer level offload mechanism may reduce complexity over conventional packet level or PDN level offload.

2 is a block diagram showing an internal structure of an 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.

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

The backhaul measuring unit 210 periodically or non-periodically measures the state of the backhaul. The state of the backhaul may mean the congestion level of the backhaul. Alternatively, the state of the backhaul may refer to a QoS level that can be supported depending on the state of the current backhaul.

 To this end, the backhaul measurer 210 may measure an end to end delay and a loss rate. Then, the backhaul measuring unit 210 can 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 can be used as a parameter for determining whether each bearer is mapped to CN or SIPTO.

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

The offload manager 220 receives the backhaul measurement result from the backhaul measurer 210. The offload manager 220 may periodically or non-periodically report the measurement result from the backhaul measuring unit 210 or may request the backhaul measuring unit 210 to measure and report the channel state of the backhaul.

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

More specifically, the operator policy can be set to offload the flow based on user subscription information or the like. The operator policy may be set via the SIPTO flag (SIPTO Flag) in embodiments of the present invention.

In addition, the session continuity support of the upstream may be determined by information such as operator policy, application type, application provider, and the like. The continuity support of the flow may be established 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), etc. In contrast to this QoS parameter, the SIPTO flag ), And a session continuity flag (Session Continuity Flag). Hereinafter, the SIPTO flag (SIPTO Flag) and the session continuity flag (Session Continuity Flag) may be referred to as a bearer-related parameter. The bearer-related parameter may include conventional QCI information in addition to the SIPTO flag (SIPTO Flag) and the session continuity flag (Session Continuity Flag).

For example, in the past, flows having the same QCI have all been allocated to the same bearer. On the other hand, according to the embodiment of the present invention, even if the QCI is the same flow, each flow can be assigned to a different buffer if the setting of the SIPTO flag (SIPTO Flag) and the session continuity flag (Session Continuity Flag) are different.

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

In the embodiment of the present invention, the SIPTO flag and the Session Continuity Flag may be added as additional parameters for forming an arbitrary bearer, and the offload manager 220 may determine, based on the parameters, The mapping relationship of the bearer can be determined.

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

SIPTO  flag( SIPTO  Flag) Session continuity flag ( Session  Continuity Flag ) Whether the bearer QCI is supported by the backhaul (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, the bearer for which the SIPTO flag (SIPTO Flag) is set to NO is mapped to the CN. This is because it is decided by operator policy not to offload the bearer.

Also, if the SIPTO flag (SIPTO Flag) is set to Yes but the current backhaul condition does not guarantee QCI, the bearer is mapped to CN. According to an embodiment of the present invention, even if the SIPTO flag (SIPTO Flag) is set to 1, the bearer can be offloaded only when the backhaul state guarantees a certain level of quality of service without unconditionally offloading the bearer have.

Also, if the SIPTO flag (SIPTO Flag) is set to Yes, the Session Continuity Flag is set to NO, and the state of the current backhaul can guarantee QCI, then the bearer can be mapped to SIPTO .

If the SIPTO flag (SIPTO Flag) is set to Yes, the Session Continuity Flag is set to Yes, and the state of the current backhaul can guarantee QCI, the bearer can be guaranteed by the backhaul It can be mapped to SIPTO or CN according to the level of QoS. For example, if the QoS level guaranteed by the backhaul is less than a predetermined threshold, the bearer may be mapped to the CN, and if the QoS level that the backhaul can guarantee is greater than or equal to a preset threshold value, .

As described above, according to the embodiment of the present invention, the offload manager 220 of the offload management device 200 transmits an arbitrary bearer to either CN or CIPTO based on the buffer-related parameters and the channel state of the backhaul It is possible to decide whether or not to perform mapping.

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

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

First, the offload management device 200 establishes at least one bearer in step S310. According to an embodiment of the present invention, the bearer may be distinguished according to at least one of QCI or bearer related parameters. For example, bearers with different QCIs can be distinguished from each other. Also, even if the QCI is the same, the bearers with different bearer-related parameters can be distinguished from each other. The bearer-related parameter may include at least one of a SIPTO flag (SIPTO Flag) or a Session Continuity Flag.

In step S320, the offload management device 200 determines whether the SIPTO flag (SIPTO Flag) is set to On (Yes) among the bearer-related parameters for an arbitrary bearer. If the SIPTO flag (SIPTO Flag) is not set to On (Yes), the offload management device 200 proceeds to step S350 and maps the bearer to the CN. In other words, the offload management device 200 maps the bearer to the core network without offloading the bearer.

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

As a result of the determination, if not, the offload management device 200 proceeds to step S350 and maps the bearer to the CN. In other words, the offload management device 200 maps the bearer to the core network without offloading the bearer.

As a result of the determination, if it is supported, the offload management device 200 proceeds to step 340 and determines whether the mobility support is set to On (Yes). If not, the offload management device 200 proceeds to step S360 and maps the bearer to SIPTO. In other words, the offload management device 200 offloads the bearer.

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

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

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

There are two kinds of offload decision changes as follows. The first is when the bearer mapped to (or decided to be mapped to) CN is changed to being mapped to SIPTO, and the second is when the bearer mapped to (or decided to be mapped to) SIPTO is changed to mapped to CN to be. For example, when the bearer mapped to the SIPTO is mapped to the CN, the channel state of the core network becomes good.

If the Session Continuity Flag is set to Off among the above two types of bearers, the bearer may be released.

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

The above cases are summarized in the table below.

Session continuation flag ( Session  Continuity Flag ) Action Yes CN / IP tunneling the traffic from P-GW to H (e) NB to keep the bearer mapping to the CN / IP tunneling traffic from the P-GW to the home base station. No Initiate Release of bearer

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

The above cases are summarized in the table below.

Session continuation flag Session  Continuity Flag Action Yes (QoS) / Release of bearer which breaks the session. No Initiate Release of bearer

The operation will be described with reference to FIG.

First, the offload management device 200 determines whether a change is detected in the SIPTO QCI in step S410. If a change is detected, the offload management device 200 starts the determination as to whether or not it is necessary to change the mapping setting for each bearer in step S420.

To this end, the offload management device 200 evaluates the offload determination in step S430. If it is determined in step S440 that a change has occurred in the offload determination, the offload management device 200 determines whether or not the session continuity flag is set to Yes (On) in step S450 .

If it is not set to Yes, the offload management device 200 proceeds to step S460 and releases the bearer.

On the other hand, when the session continuity flag is set to Yes, the offload management device 200 proceeds to step S470 and determines whether the offload decision change is a change from SIPTO to CN, or from CN to SIPTO .

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

On the other hand, in the case of a change from CN to SIPTO, the offload management device 200 can proceed to step S490 and maintain the mapping setting to the CN.

Then, the offload management device 200 proceeds to step S495 and repeats the above process for the next bearer.

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

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

The offload management device 200 may periodically or non-periodically monitor the bearer modification. The offload determination can be evaluated and maintained or changed according to the monitoring result. The above contents will be described concretely through the flowchart of FIG.

First, the offload management device 200 determines whether a bearer modification has occurred for any of the bearers in step S510.

If an occurrence is detected, the offload management device 200 starts the evaluation for the previously performed offload determination to determine whether it is necessary to change the offload determination for each bearer in step S520.

If it is determined in step S530 that a change has occurred in the offload determination, the offload management device 200 determines whether or not the session continuity flag (Session Continuity Flag) is set to Yes (On) in step S540 .

If not set to Yes, the offload management device 200 proceeds to step S550 and releases the bearer.

On the other hand, if the session continuity flag is set to Yes, the offload management device 200 proceeds to step S560 and determines whether the offload decision change is a change from SIPTO to CN or from CN to SIPTO .

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

On the other hand, in the case of a change from CN to SIPTO, the offload management device 200 may proceed to step S580 and maintain the mapping setting to the CN.

Then, the off-load management device 200 proceeds to step S590 and repeats the above-described process for the next bearer.

6A is a flowchart showing a process of delivering the parameters so that a bearer can be directly set based on bearer-related parameters determined by an operator policy according to an embodiment of the present invention.

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

Then, the PDN GW 640 generates the bearer including the SIPTO Flag and the Session Continuity Flag parameter as the bearer setup value in the initial bearer generation.

In addition, the S-GW 630 and the eNB 610 generate a bearer including a SIPTO Flag and a Session Continuity Flag parameter as a bearer setting value in bearer generation.

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

The application function (AF) 660 may forward the service notification message to the policy charging and rules function (PCRF) 650 in step S680. Then, in step S681, the PCRF 650 transmits an IP-CAN session modification message to the PDG GW 640. [ The PCRF 640 may then forward the Policy and Charging Rule Provisioning message to the PDG GW 640 in step S682. The policy and billing rule provisioning message may include a bearer-related parameter, e.g., a SIPTO Flag and a Session Continuity Flag, according to one embodiment of the present invention.

In step S683, the PDN GW 640 may transmit a Create Bearer Request message to the Serving GW 630. [ The bearer creation request message instructs to generate a bearer including a SIPTO Flag and a Session Continuity Flag parameter as a bearer setup value in the initial bearer generation.

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

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

Then, in step S686, the BS 610 transmits an RRC Connection Reconfiguration message to the AT 600. Then, in step S687, the UE 600 transmits an RRC Connection Reconfiguration Complete message to the BS 610.

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

Then, 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, in step S691, the MME 620 transmits a Create Bearer Response message to the Serving GW 630. [

In step S692, the Serving GW 630 transmits a Bearer Create Response message to the PDN GW 640. [ Then, in step S692, the PDN GW 640 transmits an IP-CAN session modification message to the PCRF 650. [

As can be seen from the above process, the PDN GW 640 can generate a bearer including the SIPTO Flag and the Session Continuity Flag parameter as the bearer setup value in the initial bearer generation.

FIG. 6B is a flowchart illustrating a process of maintaining an existing bearer system according to an embodiment of the present invention and delivering a bearer-related parameter determined by an operator policy to a message to an offload management device.

More specifically, FIG. 6 illustrates a process in which a bearer-related parameter is transferred 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 (SIPTO Flag) and a Session Continuity Flag. The bearer-related parameter may be transmitted to the home base station or the base station as additional information in a bearer setup process.

As described below, the bearer-related parameter is transmitted to a MME in a bearer activation or modification process, and the MME transmits the bearer-related parameter to a home base station or a base station It can be passed to the offload manager.

While managing mobility, the bearer-related parameters may be communicated to the target base station.

The above content 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 (PCRF) 650 in step S605. Then, in step S610, the PCRF 650 transmits an IP-CAN session modification message to the PDN GW 640. [ The PCRF 650 may then forward the Policy and Charging Rule Provisioning message to the PDG GW 640 in step S615. The policy and billing rule provisioning message may include a bearer-related parameter, e.g., a SIPTO Flag and a Session Continuity Flag, according to one embodiment of the present invention.

In step 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.

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

In step S630, the MME 620 may store the received SIPTO flag (SIPTO Flag) and the session continuity flag (Session Continuity Flag).

In step 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 setup request message or the session management request message may include a received SIPTO flag and a session continuity flag.

Then, in step S640, the BS 610 transmits an RRC Connection Reconfiguration message to the AT 600. Then, in step S645, the UE 600 transmits an RRC Connection Reconfiguration Complete message to the BS 610.

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

Then, 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. In step S665, the MME 620 transmits a Create Bearer Response message to the Serving GW 630. [

In step S670, the Serving GW 630 transmits a Bearer Create Response message to the PDN GW 640. [ Then, in step S675, the PDN GW 640 transmits an IP-CAN session modification message to the PCRF 650. [

As can be seen from the above process, the bearer-related parameters may be transmitted to the base station 610 including the offload management device via the MME 620 in a dedicated bearer activation process.

FIG. 7 is a flowchart illustrating a process of transmitting the change when a bearer-related parameter is changed according to an embodiment of the present invention.

As shown below, when a change is made to a bearer-related parameter, the PCRF may provide a PCC rule to the updated bearer.

7, the application function (AF) 760 may transmit a service notification message to the policy charging and rules function (PCRF) 750 in step S705. Then, in step S710, the PCRF 750 transmits an IP-CAN session modification message to the PDG GW 740. [ The PCRF 750 may then forward the Policy and Charging Rule Provisioning message to the PDG GW 740 in step 715. The policy and billing rule provisioning message may include a bearer-related parameter, e.g., a SIPTO Flag and a Session Continuity Flag, according to one embodiment of the present invention.

In step S720, the PDN GW 740 may forward the Update Bearer Request message to the Serving GW 730. [

In step S725, the Serving GW 730 may transmit an Update Bearer Request message to the MME 720. [

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, in step S735, the BS 710 transmits an RRC Connection Reconfiguration message to the MS 700. [ In step S740, the MS 700 transmits an RRC Connection Reconfiguration Complete message to the BS 710. [

Then, the BS 710 transmits a Bearer Modify Response message to the MME 720 in step S745.

Then, 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. In step S760, the MME 720 transmits an Update Bearer Response message to the Serving GW 730. [

In step S765, the Serving GW 730 transmits an Update Bearer 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.

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

According to an embodiment of the present invention, the PCRF may decide to delete (or release) the bearer due to reasons such as operator policy being changed. After a plurality of bearers are established for SIPTO or CN, and all flows have been transferred to SIPTO / non-SIPTO, the other bearers may be deleted using the bearer deactivation procedure.

The above contents will be described concretely through the flowchart of FIG. 8, the PDN GW initiates bearer deactivation.

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

In step 815 and step 850, the Serving GW 840 may transmit a bearer delete request message to the MME 820 and the SGSN 830, respectively.

Then, the MME 820 can transmit a detach request message to the terminal 800 in step S825. In step S830, the MME 820 initiates a trigger for reactivation in the ECM-IDLE.

In step S835, the MME 820 may transmit a bearer deactivation request message to the BS 810. [ In step S840, the BS 810 transmits an RRC connection re-establishment message to the MS 800, and the MS 800 transmits an RRC connection re-establishment completion message to the BS 810 in step S845.

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

The UE 800 transmits a direct transmission message to the BS 810 in step S855 and transmits an EPS Bearer Context Inactivity Accept message to the MME 820 in step S860. Then, the terminal 800 may transmit a detach accept message to the MME 820 in step S865.

In step S870, the MME 820 transmits a bearer deletion response message to the Serving GW 840, and the SGSN 830 transmits the bearer deletion response message to the Serving GW 840 in step S875.

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

The terminal 800 can release the signaling connection through the signaling between the base station 810 and the MME 820 in step S890.

9 is a flowchart illustrating a process of deactivating a bearer according to an embodiment of the present invention. 9 is a flowchart of a method by which the MME initiates bearer deactivation.

When determining whether to offload, if any bearer is to be released, the base station will trigger the release of that bearer, and the bearer release can be initiated by the MME.

First, the terminal 900 can transmit a radio bearer release message to the base station 900 in step S905. The base station 910 may then forward the bearer release indicator to the MME 920 in step 910. In step S915, the MME 920 can transmit a bearer delete command to the Serving GW 930. [

In step S920, the Serving GW 930 may transmit a bearer deleting command to the PDN GW 940. In step 925, the PDN GW 940 sends an IP-CAN session modification message to the PCRF 950 .

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

In step S945, the MME 920 transmits a bearer deletion response message to the Serving GW 930, and the Serving GW 930 can forward the bearer deletion response message to the PDN GW 940 in step S950.

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

In step S1005, the home subscriber server (HSS) transmits a subscriber data insertion message to the MME 1030. [ In step S1010, the MME transmits a subscriber data insertion confirmation message to the HSS 1070. [

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. In step S1025, the Serving GW 1040 transmits a bearer modification command message to the PDN GW 1050. [ Then, in step S1030, the PDN GW 1050 transmits and receives an IP-CAN session modification message to and from the PCRF 1060.

Then, in step S1035, the PCRF 1060 delivers a policy and billing rule preparation message to the PDN GW 1050. [ The policy and billing rule preparation message may include a SIPTO flag (SIPTO Flag) and a Session Continuity Flag according to an embodiment of the present invention. The PDN GW 1050 can forward the bearer update request message to the Serving GW 1040 in step S1040.

In step S1045, the bearer correction procedure is performed.

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

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

11A is a diagram showing SIPTO according to the prior art. 11A shows SIPTO status for multiple PDNs.

As shown in FIG. 11A, a plurality of IP sessions 1100 and 1110 may each include at least one EPS bearer. The bearers initially created are referred to as default EPS bearers 1101 and 1111, and the bearer generated thereafter is referred to as a dedicated EPS bearer.

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 the L-GW is predetermined at the time of bearer generation, and bearers included in the same IP session are all mapped to the core network or L-GW in the same way. For example, all of the bearers 1101, 1102, 1103 and 1104 belonging to the IP session 1100 are all mapped to the core network and all of the bearers 1111, 1112, 1113 and 1114 belonging to the IP session 111 are mapped to L -GW. In this case, the bearer 1102 belonging to the IP thin line 1100 can not be mapped to the L-GW.

11B is a diagram showing 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, in addition to QoS, an element that determines the characteristics of the bearer may further include a bearer-related parameter (SIPTO Flag, Session Continuity Flag, etc.).

Further, according to the embodiment of the present invention, each of the bearers 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, bearer 1121, bearer 1122 may be mapped to the core network, and bearer 1122, bearer 1124 may be mapped to L-GW, even though bearers belonging to the same IP session 1120 .

According to the present invention described above, SIPTO can be supported for all kinds of traffic.

The embodiments of the present invention disclosed in the present specification and drawings are intended to be illustrative only and 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 are possible in addition to the embodiments disclosed herein.

Claims (14)

A method for offloading traffic in an offload management device in a wireless communication system,
Confirming a bearer-related parameter for an arbitrary bearer;
Confirming a channel state of a backhaul of the wireless communication system; And
Determining whether to offload the bearer based on the identified bearer-related parameters and the channel state for the backhaul. 2. The method of claim 1, wherein the bearer-
A Selective IP Traffic Offload (SIPTO) flag, or a Session Continuity flag that determines whether to offload the bearer. 2. The method of claim 1,
The degree of congestion for the backhaul, or the degree of quality of service that can be supported according to the state of the backhaul. 3. The method of claim 2,
Wherein the SIPTO flag and session continuity flag support are set based at least on at least one of user subscription information, operator policy, application type, or application provider. 2. The method according to claim 1,
If quality control information (QCI) for the bearer is not supported by the channel status for the confirmed backhaul,
Wherein the bearer is mapped to a core network (CN) without offloading any of the bearers. 3. The method according to claim 2,
Detecting that a channel state of the backhaul has changed;
Determining whether there is a change in an offload decision for the arbitrary bearer due to a channel state of the modified backhaul; And
If there is a change, further comprising the step of maintaining an offload decision for the random bearer or releasing the random bearer according to the Session Continuity flag and the type of offload decision change The method comprising the steps of: 3. The method according to claim 2,
Detecting that modification of any of the bearers due to a change in a provider policy or user subscription information has occurred;
Determining whether there is a change in an offload decision for the arbitrary bearer due to modification to the arbitrary bearer; And
If there is a change, further comprising the step of maintaining an offload decision for the random bearer or releasing the random bearer according to the Session Continuity flag and the type of offload decision change The method comprising the steps of: An offload management device for managing traffic offload in a wireless communication system,
A backhaul measuring unit measuring a channel condition of a backhaul of the wireless communication system; And
Determining bearer-related parameters for any bearer, identifying channel conditions for the backhaul of the wireless communication system, and determining whether to offload the bearer based on the identified bearer-related parameters and channel conditions for the backhaul And an offload manager that determines the offload manager. 9. The method of claim 8, wherein the bearer-
A Selective IP Traffic Offload (SIPTO) flag or a Session Continuity flag for determining whether to offload the bearer. 9. The backhaul apparatus according to claim 8,
Wherein the at least one of the degree of congestion of the backhaul and the degree of quality of service that can be supported according to the state of the backhaul is measured. 10. The method of claim 9,
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. 9. The system according to claim 8,
If quality control information (QCI) for the bearer is not supported by the channel status for the confirmed backhaul,
And not to offload the arbitrary bearer to a core network (CN). 10. The system according to claim 9,
Determining whether there is a change in the offload determination for the arbitrary bearer due to the channel state of the changed backhaul when the channel state of the backhaul is changed, Continuity flag and an offload decision change type, or controls to release the arbitrary bearer. 10. The system according to claim 9,
If there is a change in the offload decision for the arbitrary bearer due to the modification to the arbitrary bearer when detecting that modification of the arbitrary bearer due to a change in the provider policy or the user's subscription information has occurred , And if there is a change, maintains an offload determination for the certain bearer according to the Session Continuity flag and the type of the offload decision change type, or controls to release the arbitrary bearer And a control unit for controlling the output of the control unit.

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