CN1925672A - Method for transferring user terminal in service universal grouping wireless business supporting node pool - Google Patents

Abstract

This invention discloses one method to transfer user terminal on sharing set wireless supportive points, which comprises the following steps: source SGSN determines user terminal and matching virtual NRI P-TMSI; then sending back source SGSN to user terminal with P-TMSI and one designed time length; user terminal receives update responding and starts updating requirement according to designed time length; RAN determines the user transferring according to designed time length to start timer; then the user terminal selects SGSN as user terminal service.

Description

Method for Transferring User Terminals in Supporting Node Pool for Serving General Packet Radio Service

technical field

The present invention relates to core network technology, in particular to a method for transferring a user terminal in a serving general packet radio service (GPRS) support node (SGSN, Serving GPRS Support Node) pool.

Background technique

According to the 3rd Generation Partnership Project (3GPP, 3rd Generation Partnership Project) standard, a radio access network (RAN, Radio Access Network) node can be connected to multiple core network (CN, Core Network) nodes to form a many-to-many correspondence . The RAN node can be a radio network controller (RNC, Radio Network Controller) or a base station controller (BSC, Basic Station Controller). The CN node in the circuit domain is the Mobile Switching Center (MSC, Mobile Switching Centre), and the CN node in the packet domain is the SGSN.

The concept of a pool area is proposed in the 3GPP standard. A pool area refers to an area covered by multiple RAN nodes. When a user terminal roams in the pool area, the CN node that provides services for the user terminal may not change, which can reduce the number of nodes due to CN node changes. The number of execution times of the location update process caused by this reduces the signaling interaction between CN nodes.

A pool area is usually served by multiple CN nodes in parallel, of course, it can also be served by one CN node. When a pool area is served by multiple CN nodes in parallel, these CN nodes form a CN node pool, that is, an MSC pool or an SGSN pool. One CN node pool can provide services for multiple pool areas at the same time, that is, one CN node pool can correspond to multiple pool areas.

In order to uniquely identify a CN node in a CN node pool, each CN node in the CN node pool is assigned one or more Network Resource Identifiers (NRI, Network Resource Identifier), and the assigned NRI is configured on the CN node through operation and maintenance , used to identify different CN nodes in a CN node pool. When a CN node assigns a temporary mobile subscriber identity (TMSI, Temporary Mobile Subscriber Identity) or packet temporary mobile subscriber identity (P-TMSI, Packet Temporary Mobile Subscriber Identity) to a user terminal, insert the CN node's ID into the TMSI/P-TMSI NRIs. The NRI with a variable length of 0 to 10 bits is located in the 23rd to 14th bits of the TMSI/P-TMSI. The TMSI is allocated to the user terminal by the CN node in the circuit domain, that is, the MSC; the P-TMSI is allocated to the user terminal by the CN node in the packet domain, that is, the SGSN. The actual effective bit length of NRI in TMSI/P-TMSI depends on the network planning and can be configured through the Operation and Maintenance Center (OMC).

Each RAN node in a pool area is configured with a corresponding relationship between the NRI in the CN node pool and each CN node. In the CN node pool, each CN node is configured with a corresponding relationship between the NRI and other CN nodes.

When the user terminal enters the pool area, the CN node providing service for the user terminal, that is, the serving CN node includes the NRI of the serving CN node in the TMSI/P-TMSI allocated to the user terminal. In the pool area, each time a user terminal establishes a Non-Access Stratum (NAS, Non-Access Stratum) connection to a CN node, the RAN node routes the initial NAS message to the CN node corresponding to the NRI according to the NRI. In this way, the user terminal can use the same CN node in one pool area. The user terminal equipment may be a mobile station (MS) in the Global System for Mobile Communications (GSM, Global System for Mobile Communications), or a UE in a Universal Mobile Telecommunications (UMTS, Universal Mobile Telecommunications Service) system.

If a pool area is configured in the network, when the CN node is overloaded or the CN node is preparing to perform maintenance operations (O&M), such as restarting before the version upgrade, it is necessary to smoothly transfer the user terminals in the CN node to other CN nodes in the CN node pool middle. In order to meet the above requirements, each SGSN in the SGSN pool is assigned a virtual NRI and a non-broadcast Routing Area Identity (RAI, Routing Area Identity). The virtual NRI is different from each NRI in the SGSN pool, and each SGSN is configured with a special RAI, which may be called non-broadcast RAI, is different from broadcast RAI. When the user terminal performs GPRS attachment or Routing Area Update (RAU, Routing Area Update), the SGSN determines whether to transfer the user terminal. When the SGSN determines that the user terminal needs to be transferred, it allocates the P-TMSI containing the virtual NRI for the user terminal, and then the SGSN in The RAU response (Routing Area Update Accept) or the attach response (AttachAccept) returned to the user terminal carries the non-broadcast RAI and the allocated P-TMSI; after the user terminal receives the RAU response or the attach response, it sends the non-broadcast RAI Compared with the RAI stored by itself, since the comparison result is not the same, the user terminal quickly initiates a new routing area update or attachment update; the RAN node determines that the user terminal needs to be transferred according to the virtual NRI provided by the user terminal, and then reconnects the user terminal Select other SGSNs in the SGSN pool as the serving SGSN of the user terminal, and the RAU request (Routing Area Update Request) or attach request (AttachAccept) sent by the user terminal is routed by the RAN node to the new serving SGSN of the user terminal, routing update process or GPRS attachment After the process ends, the user terminal is transferred to the new SGSN. Hereinafter, the original serving SGSN of the user terminal is called the source SGSN, and the serving SGSN reselected for the user terminal is called the target SGSN.

Figure 1 shows the flow chart of transferring user terminals in the SGSN pool in the prior art. As shown in Figure 1, taking the user terminal as UE, the RAN node as RNC, and UE initiating routing area update as an example, the realization of transferring UE in the SGSN pool The process consists of the following steps:

Step 101: The UE establishes a radio resource control (RRC, Radio Resource Control) connection with the RNC, and the RNC allocates and establishes channel resources of the air interface for the UE. The establishment process of the RRC connection follows the provisions of the 3GPP standard TS25.331.

Step 102: The UE sends an initial direct transfer message (INITIAL DIRECTTRANSFER) to the RNC, requesting the RNC to route the non-access stratum message (NASMessage) carried in the initial direct transfer message to the serving SGSN, and establish an Iu connection with the SGSN. The access layer message parameter is the encapsulated RAU request.

Step 103: After receiving the initial direct transmission message, the RNC selects an SGSN according to the routing parameter (Routing Parameter) carried in the initial direct transmission message, and the SGSN is the source SGSN. RNC sends initial UE message (INITIAL UE MESSAGE) to source SGSN, and establishes Iu connection with source SGSN, carries non-access stratum message in this initial UE message, and this non-access stratum message parameter is the RAU request after encapsulation.

Step 104: After the source SGSN receives the initial UE message, it obtains the RAU request through the non-access stratum message parameters. The source SGSN determines that the UE needs to be transferred to other SGSNs in the SGSN pool. If the source SGSN is overloaded or needs to perform specific maintenance operations, the source SGSN A P-TMSI is allocated to the UE, and the NRI included in the P-TMSI is the virtual NRI of the source SGSN.

Step 105: the source SGSN returns a RAU response to the UE, and the RAU response carries the non-broadcast RAI of the source SGSN and the newly allocated P-TMSI.

Step 106: After receiving the RAU response, the UE stores the P-TMSI carried in the RAU response, and then returns a RAU completion message (Routing Area Update Complete) to the source SGSN, notifying the source SGSN that the routing area update has been completed.

Step 107: After receiving the RAU completion message, the source SGSN sends an Iu release command (IU RELEASE COMMAND) to the RNC to instruct the RNC to release the Iu connection.

Step 108: After receiving the Iu release command, the RNC releases the RRC connection and its related air interface resources, and releases the Iu connection and its related transmission resources. The release process of the RRC connection complies with the provisions of the 3GPP standard TS25.331.

Step 109: After the RRC connection and the Iu connection are released, the RNC returns an Iu release completion message (IU RELEASE COMPLETE) to the source SGSN, notifying the source SGSN that the Iu connection has been released.

Step 110: After receiving the RAU response, the UE compares the non-broadcast RAI carried in the RAU response with the RAI stored in itself. Since the comparison result is different, the UE initiates a routing area update again.

Steps 111 to 112 are the same as steps 101 to 102.

Step 113: After the RNC receives the initial direct transfer message, it determines that the routing parameter carried in the initial direct transfer message is a virtual NRI, and the RNC selects a serving SGSN for the UE according to the load status of each SGSN in the SGSN pool, and the SGSN is the target SGSN; The target SGSN sends an initial UE message and establishes an Iu connection with the target SGSN. The initial UE message carries a non-access stratum message, and the parameter of the non-access stratum message is an encapsulated RAU request.

Step 114: After the target SGSN receives the initial UE message, it obtains the RAU request through the non-access stratum message parameters, and then allocates a P-TMSI for the UE and updates the routing information of the UE. The NRI contained in the P-TMSI is the target SGSN's normal NRI, not the virtual NRI of the target SGSN; the target SGSN returns a RAU response to the UE, the RAU response carries the RAI of the target SGSN and the newly allocated P-TMSI, and the RAI is the RAI that the target SGSN can broadcast in the system message.

Step 115: After receiving the RAU response, the UE stores the P-TMSI carried in the RAU response, and then returns a RAU completion message to the target SGSN, notifying the target SGSN that the routing area update has been completed.

Steps 116 to 118: After the target SGSN receives the RAU completion message, it sends an Iu release command to the RNC to instruct the RNC to release the Iu connection; after the RNC receives the Iu release command, it releases the RRC connection and the Iu connection, and then the RNC returns the Iu to the target SGSN The completion message is released, so far, the routing area update process is completed.

It can be seen from the above description that in step 110, after receiving the RAU response, the user terminal will compare the non-broadcast RAI carried in the RAU response with the RAI stored in itself. Under the control of the network side, if the Iu connection is not released, the RRC connection still exists, and in step 112, the user terminal will transmit the RAU request to the RAN node through the uplink direct transmission message (UPLINKDIRECT TRANSFER), but the uplink direct transmission message does not carry The parameter NRI makes it impossible for the RAN node to determine whether to transfer the user terminal. At this time, since the Iu connection still exists, the RAN node sends the RAU request to the source SGSN through the Iu connection. In this way, the new RAU request initiated by the user terminal is sent to the source SGSN again. SGSN, if the above problems are repeated, the routing area update initiated by the user terminal will enter an infinite loop; even if the above problems are not repeated, the transmission resources on the network side will be wasted, and the RAN node and the source SGSN will perform useless processing.

Contents of the invention

In view of this, the purpose of the present invention is to provide a method for transferring a user terminal in the SGSN node pool, so as to make the transfer process of the user terminal in the SGSN node pool more perfect.

In order to achieve the above object, the present invention provides a method for transferring user terminals in the SGSN node pool, assigning a virtual network resource identifier NRI to each SGSN in the SGSN pool, and the method includes the following steps:

A. After the source SGSN determines that the user terminal needs to be transferred, it specifies a duration for the user terminal, and the source SGSN provides the virtual NRI and the specified duration to the user terminal;

B. The user terminal starts a timer according to the specified duration, and after the timer expires, initiates a new update request and provides a virtual NRI to the RAN node;

C. The RAN node of the radio access network determines that the user terminal needs to be transferred according to the virtual NRI, and transfers the user terminal to the target SGSN.

In step B, the source SGSN provides the virtual NRI and the specified duration to the user terminal, which is: the source SGSN returns an update response to the user terminal, and the update response carries the virtual NRI and the specified duration.

The update response is: a routing area update response; or: an attach response.

The step B includes: after the user terminal receives the virtual NRI and the specified duration, it sends an update completion message to the source SGSN, and then the source SGSN notifies the RAN node to release the Iu connection, and the RAN node releases the radio resource control RRC connection and the Iu connection.

The specified duration is longer than the time interval between when the user terminal sends an update completion message to the source SGSN and when the source SGSN notifies the RAN node to release the Iu connection.

The time interval is statically configured in the source SGSN.

The update request in step B is: a routing area update request; or: an attach request.

According to the method proposed in the present invention, when the source SGSN determines that the user terminal needs to be transferred, it allocates a P-TMSI containing a virtual NRI for the user terminal, and then the source SGSN carries the allocated P-TMSI and a specified NRI in the update response returned to the user terminal. Duration: After receiving the update response, the user terminal starts the timer according to the specified duration carried in the update response. After the timer expires, the user terminal initiates a new update request; the RAN node determines that the user terminal needs to update according to the virtual NRI provided by the user terminal. Transfer, and then select the target SGSN in the SGSN pool for the user terminal as the serving SGSN of the user terminal, the update request sent by the user terminal is routed to the target SGSN by the RAN node, after the update process is completed, the user terminal is transferred to the new SGSN, so that the user The time for the terminal to initiate a new routing area update is completely controlled by the network side. By making the specified time longer than the time interval between the user terminal sending an update completion message to the source SGSN and the source SGSN notifying the RAN node to release the Iu connection, the user terminal will not When the Iu connection is not released, a new routing area update request or attachment request is initiated, which improves the transfer process of the user terminal in the SGSN node pool.

In addition, since the non-broadcast RAI of the SGSN cannot be the same as the broadcast RAI, the non-broadcast RAI occupies a large amount of resources of the RAI and causes great waste to the RAI. According to the method proposed by the present invention, there is no need to configure the non-broadcast RAI for the SGSN , saving RAI resources.

Description of drawings

FIG. 1 shows a flow chart of transferring a user terminal in an SGSN pool in the prior art;

Fig. 2 shows a flow chart of transferring a user terminal in an SGSN pool in the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings.

In the present invention, a virtual NRI is assigned to each SGSN in the SGSN pool. The virtual NRI is different from the normal NRI in the SGSN pool. When the user terminal performs GPRS attachment or routing area update, the source SGSN determines whether to transfer the user terminal, and the source SGSN determines whether to transfer the user terminal. When the user terminal is transferred, the user terminal is assigned a P-TMSI containing a virtual NRI, and then the source SGSN carries the allocated P-TMSI and a specified duration in the update response returned to the user terminal, such as a RAU response or an attach response; the user terminal After receiving an update response, such as a RAU response or an attach response, the timer is started according to the specified duration carried in the update response. After the timer expires, the user terminal initiates a new update request, such as a RAU request or an attach request; The virtual NRI provided by the terminal determines that the user terminal needs to be transferred, and then selects the target SGSN in the SGSN pool for the user terminal as the serving SGSN of the user terminal, and the update request sent by the user terminal, such as an RAU request or an attach request, is routed to the target SGSN by the RAN node, After the update process, such as the route update process or the GPRS attach process, the user terminal is transferred to the new SGSN.

Fig. 2 shows the flow chart of transferring the user terminal in the SGSN pool in the present invention. As shown in Fig. 2, taking the user terminal as the UE, the RAN node as the RNC, and the UE initiating the routing area update as an example, the implementation process of transferring the UE in the SGSN pool Include the following steps:

Steps 201 to 203 are the same as steps 101 to 103 .

Step 204: After the source SGSN receives the initial UE message, it obtains the RAU request through the non-access stratum message parameters. The source SGSN determines that the UE needs to be transferred to other SGSNs in the SGSN pool. If the source SGSN is overloaded or needs to perform specific maintenance operations, the source SGSN The UE is allocated a P-TMSI, the NRI included in the P-TMSI is the virtual NRI of the source SGSN, and the source SGSN specifies the RAU duration for the UE.

Step 205: The source SGSN returns a RAU response to the UE, and the RAU response carries the RAU duration and the newly allocated P-TMSI.

Steps 206 to 209 are the same as steps 106 to 109 .

Step 210: After receiving the RAU response, the UE starts a timer according to the duration of the RAU, and executes Step 211 after the timer expires.

Steps 211 to 218 are the same as steps 111 to 118 .

The time interval between steps 206 to 207 is the time interval between the RNC receiving the RAU completion message and the source SGSN initiating the release of the Iu connection, that is, the period between the user terminal sending the RAU completion message to the source SGSN and the source SGSN notifying the RNC to release the Iu connection To ensure that the Iu connection and the RRC connection have been released when the UE initiates a new routing area update, the RAU duration must be greater than this time interval. The length of this time interval can be determined through statistical methods or experience, and can be used in SGSN The time interval is statically configured. When the SGSN specifies the RAU duration for the UE, it only needs to ensure that the RAU duration is longer than the time interval. In this way, the time for the UE to initiate a new routing area update is completely controlled by the network side, and there will be no such occurrences in the prior art. When the Iu connection is not released, the UE initiates a new routing area update problem.

The implementation of transferring the user terminal in the GPRS attach procedure is basically the same as the implementation of transferring the user terminal in the RAU update procedure, the difference is only in the transmitted message, which will not be repeated here.

In a word, the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention.

Claims (7)

1. A method of transferring a user terminal in a serving general packet radio service support node SGSN pool, characterized in that, for each SGSN in the SGSN pool, the virtual network resource identifier NRI is allocated, and the method also includes the following steps: A. After the source SGSN determines that the user terminal needs to be transferred, it specifies a duration for the user terminal, and the source SGSN provides the virtual NRI and the specified duration to the user terminal; B. The user terminal starts a timer according to the specified duration, and after the timer expires, initiates a new update request and provides a virtual NRI to the RAN node; C. The RAN node of the radio access network determines that the user terminal needs to be transferred according to the virtual NRI, and transfers the user terminal to the target SGSN. 2. The method according to claim 1, wherein the source SGSN in step B provides the virtual NRI and the specified duration to the user terminal, which is: the source SGSN returns an update response to the user terminal, and the update response carries all The above virtual NRI and specified duration. 3. The method according to claim 2, wherein the update response is: a routing area update response; or an attach response. 4. The method according to claim 1 or 2, wherein the step B comprises: after the user terminal receives the virtual NRI and the specified duration, the user terminal sends an update completion message to the source SGSN, and then the source SGSN notifies the RAN node to release the Iu connection, the RAN node releases the radio resource control RRC connection and the Iu connection. 5. The method according to claim 4, wherein the specified time length is longer than the time interval between the user terminal sending an update complete message to the source SGSN and the source SGSN informing the RAN node to release the Iu connection. 6. The method according to claim 5, wherein the time interval is statically configured in the source SGSN. 7. The method according to claim 1 or 2, wherein the update request in step B is: a routing area update request; or is: an attach request.

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