KR20050080991A - Relocation method of service nodes in mobile telecommunication network - Google Patents

Abstract

The present invention relates to a method of performing reassignment between service nodes in a mobile communication network. When a terminal moves from an existing service node to a new service node, the existing service node transmits a reassignment request delivery message to a new service node. The new service node sends the reassignment response forwarding message to the existing service node. The existing service node sets a predetermined timer after transmitting the reassignment command message to the source radio network controller in response to the reassignment response forwarding message, and the reassignment completion forwarding message is not normally received from the new service node until the timer expires. If not, it sends a reassignment cancellation request message to the new service node. This invention makes it possible to quickly recover the resources of a service node when reallocation is not normally performed.

Description

How to perform reallocation between service nodes in mobile communication network {RELOCATION METHOD OF SERVICE NODES IN MOBILE TELECOMMUNICATION NETWORK}

The present invention relates to a mobile communication network, and more particularly, to a method for reallocating access nodes to a mobile communication network.

Subscribers on wireless communications networks such as Cellular, Personal Communications Services, or International Mobile Telecommunication (IMT) -2000 communications systems can be connected via software or hardware to Internet-enabled mobile terminals, or notebook computers. You can access the Internet in any environment by connecting to your existing mobile phone using a modem.

In a digital mobile telephone network, a mobile communication network such as a European type Global System for Mobile communications (GSM) system can be divided into two parts. The first part is called a radio network composed of base stations (BSs) and base station controllers (BSCs) that control a plurality of base stations, respectively. The second part is called Core Network and consists of Mobile Switching Centers (MSCs) each responsible for a plurality of base station controllers.

The GPRS (General Packet Radio Service) communication system developed in the current mobile communication standard, especially GSM, was developed to support packet switching service with GSM. The advent of GPRS has made it possible to efficiently add additional core networks to GSM systems. The GPRS core network is serviced by Serving GPRS Support Nodes (SGSNs) and Gateway GPRS Support Nodes (GGSNs).

Universal Mobile Telecommunications System (UMTS) is a third generation communication system developed to be combined with GPRS or similar packet switching systems. The UMTS communication system supports not only voice services but also packet data services that are faster than GPRS, enabling high-speed data communications and video communications. In a UMTS communication system, a wireless network is commonly referred to as a UMTS Radio Access Network (UTRAN) or simply a RAN, and the RAN is a Radio Network Controller corresponding to Node Bs corresponding to base stations and base station controllers. Controllers: RNCs. The RNCs are connected to the SGSN of the core network through an interface called the lu interface.

If the terminal in progress of the call is to be moved and the RNC serving the service needs to be changed, the SGSN serving the terminal terminates the interface with the existing RNC (called Source RNC), and the new RNC (called Target RNC) A series of tasks connecting the interface is called Serving Radio Network System (SRNS) relocation. Whether to perform SRNS reallocation is determined by the RNC. In this case, reassignment between RNCs belonging to the same SGSN is called intra-SRNS relocation, and reassignment between RNCs belonging to different SGSNs is called inter-SRNS relocation. .

In the inter-SRNS reassignment procedure, the new SGSN will notify the existing SGSN when it is reported from the target RNC that the reassignment is complete. [3GPP TS 23.060 v4.7.0 (2002-12) GPRS Service description (Release 4), 3GPP TS 25.413 v4.7.0 (2002-12) UTRAN Iu interface RANAP signaling (Release 4), 3GPP TS 29.060 v4.6.0 (2002- 12) GPRS GTP across the Gn and Gp Interface (Release 4)]

However, when the third generation UMTS core system according to the existing 3GPP (3rd Generation Partnership Project) does not normally receive a message indicating that reassignment from the destination RNC is completed in the new SGSN due to any failure of a path or a node, SGSN did not know if SRNC reallocation was successful. In this case, there is a need for a treatment procedure between the new SGSN and the existing SGSN.

Accordingly, an object of the present invention, which is designed to solve the problems of the prior art operating as described above, is that when a reallocation between SRNCs is made, a new SGSN does not normally receive a reassignment completion message from the destination RNC, or an existing SGSN This is to provide a method of handling when a reassignment completion notification is not normally received from a new SGSN.

In order to achieve the above object, an embodiment of the present invention provides a mobile communication network for providing a packet service to a terminal by a plurality of service nodes each serving a plurality of wireless network controllers. In the method for reallocating a service node,

As the terminal moves from the service area of the source radio network controller belonging to the existing service node to the service area of the destination radio network controller belonging to the new service node, the existing service node transmits a reassignment request delivery message to the new service node. Process,

Transmitting, by the new service node, a reassignment response delivery message to the existing service node;

Setting a first timer after the existing service node transmits a reassignment command message to the source radio network controller in response to the reassignment response transfer message;

And transmitting a reassignment cancellation request message to the new service node if the reassignment completion delivery message is not normally received from the new service node until the first timer expires.

Another embodiment of the present invention is directed to a method for reallocating a service node to which a terminal accesses in a mobile communication network providing packet service to a terminal by a plurality of service nodes each serving a plurality of wireless network controllers. In

As the terminal moves from the service area of the source radio network controller belonging to the existing service node to the service area of the destination radio network controller belonging to the new service node, the existing service node transmits a reassignment request delivery message to the new service node. Process,

Establishing, by the new service node, a radio bearer with the destination radio network controller in response to the reassignment request delivery message;

Setting a predetermined timer after setting the radio bearer;

If a reassignment cancel request message is received from the existing service node before the timer expires, the new service node may further include removing a radio bearer established between the target service and the network controller. .

Hereinafter, with reference to the accompanying drawings will be described in detail the operating principle of the preferred embodiment of the present invention. In the following description of the present invention, detailed descriptions of well-known functions or configurations will be omitted if it is determined that the detailed description of the present invention may unnecessarily obscure the subject matter of the present invention. Terms to be described later are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators. Therefore, the definition should be made based on the contents throughout the specification.

First, the overall configuration of a 3rd Generation Partnership Project (3GPP) Universal Mobile Telecommunications System (UMTS) core system to which the present invention is applied will be briefly described with reference to FIG. 1.

Referring to FIG. 1, terminal equipment (TE) 10, 16, such as a personal computer (PC) or a notebook, may be a mobile terminal (MT) 12, 18. ) Enables the wireless interface. The mobile terminal 18 wishing to receive the voice-oriented line service has a mobile switching center (MSC) having a visitor location register (VLR) through a base station system (BSS) 20. It is connected to 34. The base station system 20 may also be connected to the SGSN 22.

The mobile terminal 12 wishing to receive the packet service is connected to the SGSN 22 via a UMTS Terrestrial Radio Access Network (UTRAN) 14. Here, the interface between the UTRAN 14 and the SGSN 22 is referred to as lu. Although not shown, the UTRAN 14 is composed of a plurality of Radio Network Controllers (RNCs) and a plurality of Node Bs, and may also be connected to the mobile switching center 34 through an interface called Gs. . The Serving GPRS Support Node (SGSN) 28 communicates with another SGSN 24 via an interface called Gn, and is connected to the terminal device (TE) through the GGSNs 26 and 28 connected by the Gn interface. A packet data network 42, a public land mobile network 30, or the like.

Node 36 is inter-connected to Short Message Service Center (SM-SC) 38 to provide Short Message Service (SMS) to mobile terminals 12 and 18. -Working) Mobile switching center. The node 40 provides the mobile terminals 12 and 18 through the SGSN 22 with a CAMEL service, which is an Mobile Network Enhanced Logic Application of the Intelligent Network Application Part (INAP).

The charging system 48 is connected to the SGSN 22 and the GGSN 26 through CGF (Charging Gateway Functionality) 44 to charge the terminal 12 using the packet service. The Equipment Identity Register (EIR) 46 stores user information of the terminal 12 using the packet service.

FIG. 2 is a diagram illustrating reassignment between SRNSs and updating of a routing area (RA) in a 3GPP UMTS core system.

Referring to FIG. 2, the terminal (MT) 12 moves from an area (belonging to LA1 and RA1) of the source SRNC (serving RNC) 14a to an area LA2 and RA2 of the destination RNC 14b. do. The LA has a size including an RA as an area used in a circuit network as a location area. Here, reallocation between SRNS occurs because the existing SGSN 22a to which the source SRNC 14a belongs and the new SGSN 22b to which the destination RNC 14b belongs are different.

3 illustrates a routing area update procedure after reassignment between SRNSs is completed in a 3GPP UMTS core system.

Referring to FIG. 3, after reassignment between SRNSs is completed, the location information of the terminal 12 is notified to the destination RNC 14b. The destination RNC 14b then reports the location information of the terminal 12 to the HLR 50 via the new SGSN 22a to update the routing area. According to the routing area information, the home location register (HLR) 50 provides the user profile of the terminal 12 to a new mobile switching center 34b and a new SGSN 22b connected to the destination RNC 14b. This is to ensure that both the line service by the new mobile switching center 34b and the packet service by the new SGSN 22b can be normally provided.

4 is a diagram illustrating a normal inter-SRNS reallocation procedure. Here, the operation of reassignment completion message is normally delivered to the existing SGSN through the new SGSN.

Referring to FIG. 4, when the UE MT establishes a normal packet call in step 102 and then performs SRNS reassignment as it moves from the source RNC to the destination RNC, in step 104, the source RNC belongs to an existing SGSN to which it belongs. Relocation Required message is sent. In step 106, the existing SGSN sends a forward relocation request message to the new SGSN to which the destination RNC belongs. In step 108, the new SGSN sends a relocation request message to the destination RNC.

In step 110, the destination RNC establishes a radio access bearer for the new SGSN and the UE. At 112 the destination RNC sends a Relocation Request Acknowledge message to the new SGSN informing that the radio access bearer setup is complete. In step 114, the new SGSN sends a Forward Relocation Response message to the existing SGSN.

In step 116, the existing SGSN sends a relocation command message to the source RNC. In step 118, the source RNC starts to deliver data for the terminal to the destination RNC, and in step 120, a relocation commit message. Is sent to the destination RNC. In step 122, the destination RNC sends a Relocation Detect message to the new SGSN. The new SGSN then sends a Packet Data Protocol (PDP) Context Update Request (PDP) Context Request message to the GGSN at step 128 and receives a PDP Context Response message at step 130.

Meanwhile, in step 124, the target RNC transmits a UTRAN mobility information message including its system information to the terminal, and receives a UTRAN mobility information confirm message in step 126. In step 132, the destination RNC sends a relocation complete message to the new SGSN. The new SGSN then forwards the relocation complete message to the existing SGSN in step 134 and receives a forward relocation complete acknowledgment message in step 136.

In step 138, the new SGSN sends an Iu Release Command message to the existing SGSN, and in step 140, it receives an Iu Release Complete message. Finally, in step 142, the routing area update is performed according to the aforementioned procedure of FIG. 3.

As described above, the reassignment completion message is normally transferred from the new SGSN to the existing SGSN in step 134. Embodiments described below relate to a processing procedure when the reassignment completion message is not normally delivered.

5 is a message flow diagram illustrating an operation when a new SGSN does not receive a reallocation completion message from a destination RNC according to an embodiment of the present invention.

Referring to FIG. 5, when a normal packet call is generated in step 202 and the UE moves from an area of the source RNC to an area of the destination RNC, if relocation between SRNSs is determined, the source RNC belongs to the existing RNC in step 204. Send a Relocation Required message to SGSN. In step 206, the existing SGSN sends a Forward Relocation Request message to the new SGSN to which the destination RNC belongs.

In step 208 the new SGSN sends a relocation request message to the destination RNC and in step 212 receives a relocation request acknowledgment message. In step 210, a resource for a radio access bearer is allocated between the new SGSN and the destination RNC to establish the radio access bearer. Upon recognizing that the radio access bearer setup is completed, in step 214, the new SGSN transmits a forward relocation response message to the existing SGSN.

In step 216, the existing SGSN sends a relocation command message to the source RNC, and the role of the source RNC is transferred to the destination RNC. In step 218, the existing SGSN starts a timer T _RELComplete set to a predetermined time for waiting for a response to the reassignment command message. The timer T _RELComplete ends when a Forward Relocation Complete message is received from the new SGSN to the existing SGSN.

In step 224, if the timer T _RELComplete expires, that is, a timeout occurs, in _step 222 without receiving a Forward Relocation Complete message from the new SGSN to the existing SGSN, in step 224 the existing SGSN is replaced with the new SGSN. A relocation cancel request message is sent to the SGSN to indicate that SRNS reassignment cannot be performed normally. In step 226, the new SGSN responds with a Relocation Cancel Response message to the existing SGSN. At this time, the radio bearer connection between the source RNC and the terminal is released and the call is disconnected.

The reassignment cancellation request message is sent from the existing SGSN to the new SGSN when a failure occurs in the source RNC in the SRNS reassignment procedure according to the 3GPP TS29.060 standard. If the reception fails, it can be sent from the old SGSN to the new SGSN. At this time, the reassignment cancellation request message of step 224 is a field indicating a cause, and includes a cause value indicating that a timeout has occurred in the timer T _RELComplete , that is, the reception of the reassignment complete delivery message has failed. do.

In step 228, the existing SGSN transmits an Iu Release Command message to a source RNC for reassignment cancellation processing for the packet call after transmitting the reassignment cancellation message, and in step 230, Iu release completion (Iu). Release Complete) message. Similarly, in step 232, the new SGSN sends an Iu Release Command message to the destination RNC in response to the reassignment cancellation message, and receives an Iu Release Complete message in step 234. The new SGSN then releases the resources allocated for the packet call with the destination RNC, i.e. the resources associated with the establishment of the radio access bearer.

6 is a case in which an existing SGSN fails to receive a reassignment completion delivery message and transmits a reassignment cancellation request message, but the new SGSN does not receive the reassignment cancellation request message due to a bad Gn interval, according to an embodiment of the present invention. A message flow diagram illustrating the operation of.

Referring to FIG. 6, if it is determined that SR MT reassignment is performed as the UE MT generates a normal packet call in step 302 and then moves from the source RNC to the destination RNC, in step 304, the source RNC belongs to the existing RNC. Send a Relocation Required message to SGSN. In step 306, the existing SGSN sends a forward relocation request message to the new SGSN to which the destination RNC belongs, and in step 308, the new SGSN sends a relocation request message to the destination RNC.

In step 310, the destination RNC sets up a radio access bearer for the new SGSN and the terminal. At 312, the destination RNC sends a Relocation Request Acknowledge message to the new SGSN informing that the radio access bearer setup is complete. In step 314, the new SGSN starts the timer _{RELCompleteAck} set to a predetermined time after receiving the reallocation request response message. The timer T _{RELCompleteAck} is stopped when a reallocation _realization response transfer message or a reallocation cancellation request message is received from the existing SGSN. The setting value of the timer T _{RELCompleteAck} is determined in consideration of the transmission characteristics of the GPRS Tunneling Protocol (GTP) interval between SGSNs.

In step 316, the new SGSN sends a Forward Relocation Response message to the existing SGSN. In step 318, the existing SGSN transmits a relocation command message to the source RNC. In step 320, the existing SGSN starts a timer T _RELComplete set to a predetermined time for waiting for a response to the reassignment command message. The timer T _RELComplete ends when a Forward Relocation Complete message is received from the new SGSN to the existing SGSN.

If, in step 322, the timer T _RELComplete expires in _step 324 without receiving a Forward Relocation Complete message from the new SGSN to the existing SGSN, in step 326, the existing SGSN is replaced with the new SGSN. By sending a relocation cancel request (Relocation Cancel Request) message to inform that SRNS reallocation can not be performed normally, in step 328 receives a Relocation Cancel Response message from the new SGSN. In step 330 the new SGSN terminates the timer T _{RELCompleteAck} in response to the reassignment cancellation request message.

The reassignment cancellation request message is sent from the existing SGSN to the new SGSN when a failure occurs in the source RNC in the SRNS reassignment procedure according to the 3GPP TS29.060 standard. If the reception fails, it can be sent from the old SGSN to the new SGSN. At this time, the reassignment cancellation request message of step 326 is a field indicating a cause, and includes a cause value indicating that a timeout has occurred in the timer T _RELComplete , that is, the reception of the reassignment complete delivery message has failed. do.

In step 332, the existing SGSN transmits an Iu Release Command message to a source RNC for reassignment cancellation processing for the packet call after transmitting the reassignment cancellation message, and in step 334, Iu release completion (Iu). Release Complete) message. Similarly, in step 336, the new SGSN sends an Iu Release Command message to the destination RNC in response to the reassignment cancellation message, and receives an Iu Release Complete message in step 338. The new SGSN then releases the resources allocated for the packet call with the destination RNC, i.e. the resources associated with the establishment of the radio access bearer.

In FIG. 6, when the T _{RELCompleteAck} times out, the call is released because the reassignment completion message has not been received from the destination RNC and the reassignment procedure is incompletely terminated.

FIG. 7 is a message flow diagram illustrating an operation in which an existing SGSN normally receives a reassignment completion delivery message but fails to receive a reassignment cancellation request message due to a bad Gn interval according to an embodiment of the present invention.

Referring to FIG. 7, if it is determined in step 402 that SR MT reassignment is performed as the UE MT generates a normal packet call and moves from the source RNC to the destination RNC, in step 404, the source RNC belongs to the existing RNC. Send a Relocation Required message to SGSN. In step 406, the existing SGSN sends a forward relocation request message to the new SGSN to which the destination RNC belongs, and in step 408, the new SGSN sends a relocation request message to the destination RNC.

In step 410, the destination RNC establishes a radio access bearer for the new SGSN and the UE. At 412, the destination RNC sends a Relocation Request Acknowledge message to the new SGSN informing that the radio access bearer setup is complete. In step 414, the new SGSN starts the timer T _{RELCompleteAck} set to a predetermined time after receiving the reassignment request response message. The timer T _{RELCompleteAck} is stopped when a reallocation _realization response transfer message or a reallocation cancellation request message is received from the existing SGSN. The setting value of the timer T _{RELCompleteAck} is determined in consideration of the transmission characteristic of the GPRS Tunneling Protocol (GTP) interval between SGSNs.

In step 416, the new SGSN sends a Forward Relocation Response message to the existing SGSN. In step 418, the existing SGSN transmits a relocation command message to the source RNC. In step 420, the existing SGSN starts a timer T _RELComplete set to a predetermined time for waiting for a response to the reassignment command message. The timer T _RELComplete ends when a Forward Relocation Complete message is received from the new SGSN to the existing SGSN.

In step 422, the source RNC starts to deliver data for the terminal to the destination RNC, and in step 424, sends a relocation commit message to the destination RNC. Then, in step 426, the destination RNC sends a Relocation Detect message to the new SGSN. In addition, the destination RNC transmits a reassignment completion message to the new SGSN in step 428 after transmitting system information necessary for wireless access to the UE (not shown).

In step 430, the new SGSN transmits the reassignment complete delivery message to the existing SGSN in response to the reassignment complete message. Upon receipt of the reassignment complete message, the existing SGSN terminates the timer T _RELComplete in step 432 and transmits a reassignment complete response transfer message to the new SGSN in step 434. Then, in step 438, the existing SGSN sends an Iu Release Command message to the source RNC and receives an Iu Release Complete message in step 440 to release the Iu connection with the source RNC, and the terminal and the source RNC. Remove inter-radio bearer settings.

In step 436, the new SGSN receives the reallocation completion response transfer message and ends the timer T _{RELCompleteAck} . As a result, SRNS allocation is successfully completed in step 442, and the terminal performs communication through the new SGSN with the destination RNC.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by those equivalent to the scope of the claims.

In the present invention operating as described in detail above, the effects obtained by the representative ones of the disclosed inventions will be briefly described as follows.

The present invention defines a processing procedure when a new SGSN does not receive a reassignment completion message from an existing SGSN during execution of an inter-SRNS reassignment procedure in a 3GPP UMTS communication system, thereby quickly releasing a resource previously set in the new SGSN. This can increase the reusability of resources.

1 is an overall configuration diagram of a 3GPP UMTS core system.

FIG. 2 is a diagram illustrating inter-SRNS reallocation and updating of Routing Area (RA) in 3GPP UMTS core system. FIG.

3 is a diagram illustrating a routing area update procedure after reassignment between SRNSs is completed in a 3GPP UMTS core system.

4 is a diagram illustrating a normal inter-SRNS reallocation procedure.

5 is a message flow diagram illustrating operation of an existing SGSN in accordance with an embodiment of the present invention.

6 is a message flow diagram illustrating operation of a new SGSN and an existing SGSN according to another embodiment of the present invention.

7 is a message flow diagram illustrating operation of a new SGSN and an existing SGSN according to another embodiment of the present invention.

Claims (9)

A method for reallocating a service node to which a terminal accesses in a mobile communication network providing packet service to a terminal by a plurality of service nodes each responsible for a plurality of wireless network controllers, As the terminal moves from the service area of the source radio network controller belonging to the existing service node to the service area of the destination radio network controller belonging to the new service node, the existing service node transmits a reassignment request delivery message to the new service node. Process, Transmitting, by the new service node, a reassignment response delivery message to the existing service node; Setting a first timer after the existing service node transmits a reassignment command message to the source radio network controller in response to the reassignment response transfer message; Transmitting a reassignment cancellation request message to the new service node if the reassignment complete delivery message is not normally received from the new service node until the first timer expires. 2. The method of claim 1, further comprising: setting a second timer after the new service node establishes a radio bearer with the destination radio network controller in response to the reassignment request forwarding message; If a reassignment cancellation request message is received from the existing service node before the second timer expires, the new service node further includes removing a radio bearer established between the target service and the target wireless network controller. Said method. 3. The method of claim 2, further comprising the step of removing a radio bearer established with the destination radio network controller after the new service node receives the reassignment cancellation request message. 2. The method of claim 1, further comprising the step of removing a radio bearer established with the source radio network controller after the existing service node transmits the reassignment cancellation request message. 2. The method of claim 1, wherein the first timer is terminated when a reallocation reallocation message is received from the new service node before the first timer expires, and is set between the existing service node and the source radio network controller. And removing the radio bearer. A method for reallocating a service node to which a terminal accesses in a mobile communication network providing packet service to a terminal by a plurality of service nodes each responsible for a plurality of wireless network controllers, As the terminal moves from the service area of the source radio network controller belonging to the existing service node to the service area of the destination radio network controller belonging to the new service node, the existing service node transmits a reassignment request delivery message to the new service node. Process, Establishing, by the new service node, a radio bearer with the destination radio network controller in response to the reassignment request delivery message; Setting a predetermined timer after setting the radio bearer; If a reassignment cancellation request message is received from the existing service node before the timer expires, the new service node further includes removing a radio bearer established between the target service and the network controller. The method. 7. The method of claim 6, wherein if a reassignment complete response forwarding message is received from the existing service node before the timer expires, the new service node sends the terminal through a radio bearer established with the destination radio network controller. The method further comprises the step of serving. 8. The method of claim 7, further comprising the step of removing a radio bearer established with the destination radio network controller after the new service node receives the reassignment cancel request message. 7. The method of claim 6, further comprising removing a radio bearer established with the source radio network controller after the existing service node transmits the reassignment cancellation request message.