KR102402808B1 - Handover System and Handover Method - Google Patents

Abstract

A handover system and a handover method are disclosed. A handover system according to the present invention includes: a first packet data gateway to which a terminal initially accesses; a second packet data gateway locally bound to an area to which the terminal moves; and a serving gateway configured to set an interworking interface to the second packet data gateway in the handover procedure, wherein the second packet data gateway obtains transport layer session information of the mobile session from the first packet data gateway, and sends an auxiliary address to the destination server It is characterized in that binding update for updating (CoA: Care of Address) is performed.

Description

Handover system and handover method thereof

The present invention relates to a handover system and a handover method thereof, and more particularly, an IP address assigned by a previous packet data gateway after handover while seamlessly maintaining a transport layer session between a terminal undergoing handover and a service server. To a handover system and a handover method capable of changing a packet data gateway to a packet data gateway bound to a local serving gateway during handover while maintaining the basic mobile communication network function that continues to use the .

In the ^3rd Generation Partnership Project (3GPP) interworking standard (23.401) that defines handover of a Long Term Evolution (LTE) Evolved Packet Core (EPC) network, a base station, a Mobility Management Entity (MME), or a Serving (SGW) Gateway) is defined as a node that is changed, and a Packet Data Network Gateway (PGW) is defined as a node that does not change even after handover to an IP (Internet Protocol) anchor node of the terminal. In other words, the IP mobility-related standards of 3GPP comply with the mobile IP standards (RFC 5944, 3775, 5213) of the Internet Engineering Task Force (IETF). and the PGW is a node of the HA function in the LTE EPC network.

In the conventional IETF or 3GPP technology, it is defined to maintain the HoA (Home of Address) allocated from the HA in order to maintain IP connectivity with the CN (Correspondent Node) that is currently communicating even if the current terminal changes the access node. The HA node, which is an endpoint on the IP router, is defined as not changing even if the terminal moves. That is, the handover standard in which the PGW, which is the IP anchor node, is changed during LTE handover is not defined.

In addition, according to the IETF Mobile IPv6 standard, when a new IP (ie, Care of Address) is received from the access network to which the terminal has moved, the existing CN node does not transmit packets to the HA node, but transmits the new access network to the destination. The BU (Binding Update) standard for updating its own CoA to the CN is defined in order to provide an optimized packet transmission path through There is nothing defined in the standard.

When the terminal is connected to the LTE network, it continuously maintains the IP address allocated by the PGW, so that the communication session with the service server can be continuously maintained even during handover. That is, for this purpose, in the current LTE network structure, when the UE is handed over locally within the LTE network, the SGW may change, but the PGW serving as the IP anchor does not change. As a result, even if the terminal that initially accessed the PGW in a specific area moves to another area far away from the area, it is still serviced through the PGW it initially connected to, and S5 (interworking between SGW and PGW) in the WAN (Wide Area Network) section /F) traffic is generated, which causes problems such as increased end-to-end delay and disadvantages such as line investment in WAN section.

In particular, in order to reduce the network delay of the real-time IOT service in the upcoming 5th generation, optimization of the existing 4th generation LTE traffic path is required. need to be changed to

Laid-Open Patent Publication No. 10-2014-0101981 (published date: August 21, 2014)

The present invention was devised to solve the above problems, and the transport layer session between the terminal and the service server in the process of handover is maintained without interruption, and the IP address assigned by the previous packet data gateway continues to be used even after the handover. An object of the present invention is to provide a handover system and a handover method capable of changing a packet data gateway to a packet data gateway bound to a local serving gateway during handover while maintaining a mobile communication network function.

A handover system according to an embodiment of the present invention for achieving the above object includes: a first packet data gateway to which a terminal initially accesses; a second packet data gateway locally bound to an area to which the terminal moves; and a serving gateway configured to set an interworking interface to the second packet data gateway in the handover procedure, wherein the second packet data gateway obtains transport layer session information of the mobile session from the first packet data gateway, and sends an auxiliary address to the destination server It is characterized in that binding update for updating (CoA: Care of Address) is performed.

Here, the serving gateway is a target serving gateway in a region to which the terminal moves, and sets a new interworking interface to the second packet data gateway bound thereto.

In addition, the serving gateway, the IP address of the packet data gateway included in the Create Session Request (CSR) message received from the Mobility Management Entity (MME) is the IP address of the packet data gateway bound to itself and In other cases, a new interworking interface is set in the second packet data gateway.

The second packet data gateway allocates an auxiliary address of the terminal, performs traffic mapping between a home address (HoA) and an auxiliary address, and responds to a message to the target serving gateway with the home initially assigned by the previous packet data gateway. forward the address as-is.

Also, the second packet data gateway stores information on the first packet data gateway based on the session creation request message received from the target serving gateway.

In addition, when the upload traffic of the terminal occurs, the second packet data gateway updates the auxiliary address by binding update (BU) to the server, which is the corresponding destination IP address.

In addition, the second packet data gateway includes at least one of an Internet Protocol (IP), a port, a protocol, Deep Packet Inspection (DPI) information, and a Policy and Charging Control (PCC) rule to the first packet data gateway. A transport layer session including at least one Request and receive information.

In addition, the second packet data gateway updates the auxiliary address by binding update to the destination server corresponding to the transport layer session information.

The handover method for achieving the above object is a handover method performed by a handover system, wherein the terminal first accesses the first packet data gateway and then moves to a region to which the second packet data gateway is locally bound. , setting, by the target serving gateway, an interworking interface to the second packet data gateway in the handover procedure; and performing, by the second packet data gateway, the binding update to obtain the transport layer session information of the mobile session from the first packet data gateway and update the care-of address to the destination server.

Here, in the interworking interface setting step, the target serving gateway sets a new interworking interface in the second packet data gateway bound thereto.

In addition, in the interworking interface setting step, when the IP address of the packet data gateway included in the session creation request message received from the mobility management device by the target serving gateway is different from the IP address of the packet data gateway to which it is bound, the second packet data gateway Set up a new interworking interface in

In the above-described handover method, the second packet data gateway allocates an auxiliary address of the terminal, performs traffic mapping between the home address and the auxiliary address, and the home address initially allocated by the previous packet data gateway to a message responding to the target serving gateway. It may further include; passing as it is.

The handover method may further include, by the second packet data gateway, storing information on the first packet data gateway based on the session creation request message received from the target serving gateway.

Here, in the binding update step, when the second packet data gateway generates upload traffic of the terminal, the secondary address is updated by binding update to the server corresponding to the destination IP address.

In addition, the above-described handover method includes the steps of, by the second packet data gateway, requesting and receiving transport layer session information including at least one of IP, port, protocol, DPI information, and PCC rule from the first packet data gateway; may include more.

In addition, the above-described handover method may further include; updating, by the second packet data gateway, the auxiliary address by binding update to the destination server corresponding to the transport layer session information.

According to the present invention, the transport layer session between the terminal undergoing handover and the service server is maintained without interruption, and the basic mobile communication network function of continuing to use the IP address assigned by the previous packet data gateway after the handover is maintained while maintaining the handover. In case of overrun, the packet data gateway can be changed to a packet data gateway bound to the local serving gateway.

In addition, according to the present invention, by providing mobility to the packet data gateway in the mobile area during handover of the terminal, the unnecessary S5 I/F WAN section path that is inevitable in the existing 4G EPC standard is eliminated, and the network In addition to reducing latency, it is possible to reduce backhaul traffic investment.

1 is a diagram schematically illustrating a general LTE handover system.
2 is a diagram schematically illustrating an LTE handover system according to an embodiment of the present invention.
3 is a diagram illustrating a handover method of a general LTE handover system.
4 is a diagram illustrating a handover method of an LTE handover system according to an embodiment of the present invention.
FIG. 5 is a diagram illustrating an operation in which a packet data gateway in a moving area acquires existing transport layer session information and then updates an auxiliary address through binding update.

Hereinafter, an LTE handover system and a handover method thereof according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram schematically illustrating a general LTE handover system.

Referring to FIG. 1 , it is assumed that the terminal 10 first accesses a service server (CN: Correspondent Nodes) through SGW #A and PGW #A. Thereafter, assuming that the terminal 10 has moved to region #N via region #B and region #C, in the 3GPP interworking standard (23.401) defining handover of the LTE EPC core network, a base station, a mobility management device, or an SGW is defined as a node that is changed and the PGW is defined as a node that does not change even after the handover of the terminal 10, so that the LTE handover system sequentially performs each area #B and area according to the movement of the terminal 10 After setting the interworking interface S5 I/F between SGW #B and SGW #C and PGW #A corresponding to #C, finally interworking interface S5 I between SGW #N and PGW #A corresponding to region #N Set /F. However, in this LTE handover system, when the terminal 10 performs handover locally within the LTE network, the PGW serving as the IP anchor does not change even though the SGW may change, so the terminal 10 ), even if the terminal 10 that first accessed PGW #A in area A moves to area N, it is still serviced through PGW #A, which it accessed first, and SGW #B, SGW #C, SGW #N, etc. Interworking interface traffic between PGW #A is generated, and thus there are problems such as increased end-to-end delay and disadvantages such as line investment in WAN section.

2 is a diagram schematically illustrating an LTE handover system according to an embodiment of the present invention.

Referring to FIG. 2, in the LTE handover system according to the embodiment of the present invention, the transport layer session between the terminal 100 and the service server CN in the process of handover is seamlessly maintained, and even after the handover, the previous PGW 110 The following method is used to change the PGW to the PGW 130 bound to the local SGW 140 during handover while maintaining the basic LTE function that continues to use the IP address allocated from .

First, as the terminal 100 moves from the SGW #Old(120) region to the SGW #New(140) region, the target serving gateway SGW #New(140) sets the interworking interface to the existing PGW 110 instead of setting it. An interworking interface is set in the new PGW 130 locally bound to itself. In this case, the LTE handover system maintains traffic between the service server CN and the terminal 100 through the tunnel for SGW change handover until the handover is completed.

Next, the PGW 130 changed in the handover procedure obtains the transport layer session information of the mobile session by requesting the transport layer session information currently maintained from the previous PGW 110 .

Finally, the changed PGW 130 is a binding update for updating the Care of Address (CoA) to the destination server CN of the transport layer session of the terminal 100 for the transport layer session of the call. carry out the procedure

3 is a diagram illustrating a handover method of a general LTE handover system.

Referring to FIG. 3 , the PGW 24 transmits downlink data to the terminal 10 through the source SGW 20 and the source eNodeB 12 before the handover of the terminal 10 occurs ( S101 ). Here, the eNodeB, MME, and SGW before handover are named as source eNodeB 12, source MME 16, and source SGW 20, respectively, and eNodeB, MME, and SGW after handover occurs. are named as a target eNodeB 14 , a target MME 18 , and a target SGW 22 , respectively.

When the terminal 10 moves from the area of the source eNodeB 12 to the area of the target eNodeB 14, the source eNodeB 12 and the target eNodeB 14 reset the location of the terminal 10 (S103). At this time, the source eNodeB 12 requests the handover of the terminal 10 to the source MME 16 (S105), and the source MME 16 requests the target MME 18 to reset the location (S107), and the target The MME 18 requests the target SGW 22 to create a session (S109). In this case, the target SGW 22 transmits a session creation response signal to the target MME 18 (S111), and accordingly, the target MME 18 requests the target eNodeB 14 to handover the terminal 10 and (S113), a response signal to the handover request is received from the target eNodeB 14 (S115).

In addition, the target MME 18 requests the target SGW 22 to create an indirect data forwarding tunnel ( S117 ), and in response to that, when a response signal is received from the target SGW 22 , the source MME 16 requests a location reset. Transmits a response signal to (S119, S121).

In this case, the source MME 16 requests the indirect data forwarding tunnel to the source SGW 20 (S123), and in response to that, when a response signal is received from the source SGW 20, a handover command is sent to the source eNodeB 12. It transmits (S125, S127).

The source eNodeB 12 transmits the handover command received from the source MME 20 to the terminal 10 (S129), and transmits the state information to the source MME 16 (S131). In this case, the source MME 16 notifies the forward access context to the target MME 18 (S133), and receives a response signal therefrom from the target MME 18 (S135).

On the other hand, the target MME (18) transmits the state information to the target eNodeB (14) (S137). Through this, the source eNodeB 12 directly forwards to the target eNodeB 14 in the case of direct forwarding data (S139), and in the case of indirect forwarding data via the source SGW 20 and the target SGW 22 to the target eNodeB It is transmitted to (14) (S141).

When the terminal 10 is disconnected from the previous cell and synchronized to the new cell (S143), the terminal 10 transmits a handover confirmation signal to the target eNodeB 14 (S145), and accordingly, the target eNodeB 14 Downlink data is received from (S147).

In addition, the terminal 10 transmits the uplink data to the PGW 24 via the target eNodeB 14 and the target SGW 22 ( S149 ).

On the other hand, the target eNodeB 14 notifies the handover of the terminal 10 to the target MME 18 (S151). In this case, the target MME 18 notifies the source MME 16 that the relocation has been completed (S153), receives a response signal therefrom from the source MME 16 (S155), and sends a bearer to the target SGW 22 to request a correction (S157). At this time, the target SGW 22 transmits the bearer modification request to the PGW 24 (S159), and when a response signal corresponding to the bearer modification request is received from the PGW 24 (S161), the corresponding response signal is targeted It is transmitted to the MME (18) (S163).

Through this, the PGW 24 may deliver downlink data for the terminal 10 to the terminal 10 via the target SGW 22 and the target eNodeB 14 (S165), and the previous MME (source MME) ( A deletion procedure is performed for the session of 16) and the tunnel session created during handover (S167).

4 is a diagram illustrating a handover method of an LTE handover system according to an embodiment of the present invention.

Referring to FIG. 4 , the previous PGW (the PGW to which the terminal 100 first accessed) 110 is the terminal through the source SGW 120 and the source eNodeB 104 before the handover of the terminal 100 occurs. Downlink data is transmitted to (100) (S201). Here, the eNodeB, MME, and SGW prior to the handover are named as source eNodeB 102, source MME 106, and source SGW 120, respectively, and the eNodeB, MME, and SGW after handover are respectively target The eNodeB 104 , the target MME 108 , and the target SGW 140 are named.

When the terminal 100 moves from the area of the source eNodeB 102 to the area of the target eNodeB 104 , the source eNodeB 102 and the target eNodeB 104 reset the location of the terminal 100 ( S203 ). At this time, the source eNodeB 102 requests the handover of the terminal 100 to the source MME 106 (S205), and the source MME 106 requests a location reset from the target MME 108 (S207), and the target The MME 108 requests the target SGW 140 to create a session (S209). In this case, the target SGW 140 requests the PGW 130 bound thereto to create a session, and establishes an interworking interface (S211). At this time, if the target SGW 140 is different from the address of the PGW 130 bound to itself, the IP address of the PGW 110 included in the Create Session Request (CSR) message received from the target MME 108 is different. A new interworking interface is set in the PGW 130 .

In this case, the new PGW 130 allocates the care-of address (CoA) of the terminal 100 to perform traffic matching between the home address (HoA) and the care-of address (S213), and the target SGW ( 140), the PDN (Packet Data Network) address received from the target MME 108, that is, the home address initially assigned by the previous PGW 110, is delivered as it is, thereby providing transparent IP connectivity to the terminal 100. do (S215). In addition, the new PGW 130 stores information on the old PGW 110 based on the CSR message received from the target SGW 140 .

The target SGW 140 transmits the session creation response signal received from the PGW 130 to the target MME 108 (S217), and accordingly, the target MME 108 sends the hand of the terminal 100 to the target eNodeB 104. An over is requested (S219), and a response signal to the handover request is received from the target eNodeB 104 (S221).

In addition, the target MME 108 requests the target SGW 140 to create an indirect data forwarding tunnel ( S223 ), and in response, when a response signal is received from the target SGW 140 , a location reset request is made to the source MME 106 . Transmits a response signal to (S225, S227).

In this case, the source MME 106 requests the indirect data forwarding tunnel to the source SGW 120 (S229), and in response thereto is received a response signal from the source SGW 120, a handover command to the source eNodeB (102). It transmits (S231, S233).

The source eNodeB 102 transmits the handover command received from the source MME 120 to the terminal 100 (S235), and transmits the state information to the source MME 106 (S237). In this case, the source MME 106 notifies the target MME 108 of the forward access context (S239), and receives a response signal therefrom from the target MME 108 (S241).

On the other hand, the target MME 108 transmits the state information to the target eNodeB 104 (S243). Through this, the source eNodeB 102 directly forwards to the target eNodeB 104 in the case of direct forwarding data (S245), and in the case of indirect forwarding data via the source SGW 120 and the target SGW 140 to the target eNodeB It is transmitted to (104) (S247).

When the terminal 100 is disconnected from the previous cell and synchronized with the new cell (S249), the terminal 100 transmits a handover confirmation signal to the target eNodeB 104 (S251), and accordingly, the target eNodeB 104 Downlink data is received from (S253).

In addition, the terminal 100 transmits the uplink data to the PGW 130 via the target eNodeB 104 and the target SGW 140 (S255). In this case, when the upload traffic of the terminal 100 occurs, the PGW 130 updates the auxiliary address by binding update to the server (CN) 150, which is the destination IP address, and then the server 150 connects the terminal 100. It allows the traffic to be transmitted to the new PGW 130 to be routed (S257).

On the other hand, the target eNodeB 104 notifies the handover of the terminal 100 to the target MME 108 (S259). In this case, the target MME 108 notifies the source MME 106 that the relocation has been completed (S261), receives a response signal therefrom from the source MME 106 (S263), and the target SGW 140 bearer requests to be modified (S265). At this time, the target SGW 140 transmits a bearer modification request to the PGW 130 (S267), and when a response signal corresponding to the bearer modification request is received from the PGW 130 (S269), the corresponding response signal is targeted It is transmitted to the MME 108 (S271).

On the other hand, the PGW 130 requests the transport layer session information including at least one of IP, port, protocol, DPI (Deep Packet Inspection) information, and PCC (Policy and Charging Control) rules to the PGW 110 (S273) , accordingly, on the basis of the transport layer session information received from the PGW 110, if necessary, performs a rule information update procedure with PCRF (S275). In addition, the PGW 130 updates the auxiliary address with a binding update to the destination server (CN) 150 corresponding to the existing transport layer session information received from the PGW 110 , so that the destination servers are later sent to the terminal 100 . The traffic to be transmitted can be routed to the new PGW 130 (S277). In this process, a session that has already been processed through step S257 may be excluded.

Through this, the PGW 130 may transmit downlink data for the terminal 100 to the terminal 100 through the target SGW 140 and the target eNodeB 104 (S279), and the previous MME (source MME) ( 106) and the tunnel session created during handover, a deletion procedure is performed (S281).

FIG. 5 is a diagram illustrating an operation in which a packet data gateway in a moving area acquires existing transport layer session information and then updates an auxiliary address through binding update.

Referring to FIG. 5 , when the terminal 100 performs handover, the home address is maintained as it is. At this time, the new PGW 130 updates the secondary address by binding update to the corresponding destination server (CN) of the uplink packet received earlier during the handover, and transmits PDN context information, that is, from the previous PGW 110 during the handover. Obtain layer session information. Thereafter, the PGW 130 performs a binding update procedure for all destination servers (CN) based on the transport layer session information received from the previous PGW 110 .

Claims (16)

a first packet data gateway to which the terminal initially accesses;
a second packet data gateway locally bound to an area to which the terminal moves; and
a serving gateway configured to set an interworking interface to the second packet data gateway in a handover procedure;
includes,
the second packet data gateway obtains transport layer session information of the mobile session from the first packet data gateway and performs binding update for updating a care of address (CoA) to a destination server;
The serving gateway is a target serving gateway in the area to which the terminal moves, and the IP address of the packet data gateway included in a Create Session Request (CSR) message received from a Mobility Management Entity (MME) is A handover system, characterized in that when the IP address of the packet data gateway bound thereto is different from the IP address of the packet data gateway bound thereto, a new interworking interface is configured in the second packet data gateway bound thereto. delete delete According to claim 1,
The second packet data gateway,
A home address (HoA) and an auxiliary address are traffic mapped by allocating the auxiliary address of the terminal, and the home address initially assigned by the previous packet data gateway is delivered to the message responding to the target serving gateway. Handover system, characterized in that. According to claim 1,
The second packet data gateway,
and storing information on the first packet data gateway based on a session creation request message received from the target serving gateway. According to claim 1,
The second packet data gateway,
A handover system, characterized in that when upload traffic of the terminal is generated, an auxiliary address is updated with a binding update (BU) in a server that is a corresponding destination IP address. According to claim 1,
The second packet data gateway,
Requesting and receiving transport layer session information including at least one of Internet Protocol (IP), port, protocol, Deep Packet Inspection (DPI) information, and Policy and Charging Control (PCC) rules from the first packet data gateway handover system with 8. The method of claim 7,
The second packet data gateway,
A handover system, characterized in that the auxiliary address is updated by binding update to the destination server corresponding to the transport layer session information. A handover method performed by a handover system, comprising:
setting, by the target serving gateway, an interworking interface to the second packet data gateway in a handover procedure, when the terminal moves to a region to which a second packet data gateway is locally bound after first accessing the first packet data gateway; and
performing, by the second packet data gateway, a binding update for updating a care-of address to a destination server by obtaining transport layer session information of a mobile session from the first packet data gateway;
including,
In the interworking interface setting step, when the IP address of the packet data gateway included in the session creation request message received from the mobility management device is different from the IP address of the packet data gateway to which the target serving gateway is bound, the second packet data A handover method comprising setting a new interworking interface in a gateway. delete delete 10. The method of claim 9,
The second packet data gateway allocates the auxiliary address of the terminal, performs traffic mapping between the home address and the auxiliary address, and delivers the home address initially assigned by the previous packet data gateway to the message responding to the target serving gateway. step;
Handover method further comprising a. 10. The method of claim 9,
storing, by the second packet data gateway, information on the first packet data gateway based on a session creation request message received from the target serving gateway;
Handover method further comprising a. 10. The method of claim 9,
The step of performing the binding update includes:
The handover method, characterized in that the second packet data gateway updates the auxiliary address by binding update to the server corresponding to the destination IP address when the upload traffic of the terminal is generated. 10. The method of claim 9,
receiving, by the second packet data gateway, requesting and receiving transport layer session information including at least one of IP, port, protocol, DPI information, and PCC rule from the first packet data gateway;
Handover method further comprising a. 16. The method of claim 15,
updating, by the second packet data gateway, an auxiliary address by binding update to a destination server corresponding to the transport layer session information;
Handover method further comprising a.

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