WO2008154783A1

WO2008154783A1 - Method for establishing tunnel from sgsn to serving gateway

Info

Publication number: WO2008154783A1
Application number: PCT/CN2007/003848
Authority: WO
Inventors: Jinguo Zhu; Zaifeng Zong; Min Fang; Xiliang Liu
Original assignee: Zte Corporation
Priority date: 2007-06-19
Filing date: 2007-12-27
Publication date: 2008-12-24
Also published as: CN101330425B; CN101330425A

Abstract

A method for establishing a tunnel from SGSN to Serving GW includes the following steps of: the mobility management entity informing SGSN that the Serving GW changed, and informing SGSN about the address information of the new Serving GW; SGSN sending the request for establishing bearer to the new Serving GW; the new Serving GW returning the response for establishing bearer to SGSN.

Description

TECHNICAL FIELD The present invention relates to the field of communications, and in particular, to a method for establishing a tunnel of a GPRS support node (SGSN) to a monthly service gateway. BACKGROUND With the rapid development of World Interoperability for Microwave Access (Wimax), if third-generation mobile communication systems are to maintain their strong competitiveness in the field of mobile communications, they must improve their network performance and reduce their performance. The cost of network construction and operations. Therefore, the current 3GPP (3rd Generation Partnership Project, 3rd Generation Partnership Project) is working on Packet Switch Core (PS Core) and Global Mobile Voice System Wireless. The evolution of the Universal Mobile Telecommunication System Radio Access Network (UTRAN), the subject of this research is called system architecture evolution.

(System Architecture Evolution, SAE for short), the purpose is to enable the evolved PS Core to provide higher transmission rates and shorter transmission delays, optimize packets, and support evolved UTRAN (Evolved UTRAN, E-UTRAN), UTRAN > Mobility management between Wireless Local Area Network (WLAN), and other non-3GPP access networks. Currently, the architecture of the SAE is as shown in Figure 1, which includes the following network elements: Evolved RAN (E-RAN): can provide higher uplink/downlink rates, lower transmission delays, and More reliable wireless transmission. The network element included in the E-RAN is an evolved Node B (eNodeB), which can provide radio resources for user access; Home Subscriber Server (HSS): used to permanently store user subscriptions. Data; Packet Data Network (PDN): used to provide services to users; E-Packet Core: It can provide more delay and allow more wireless access systems to connect In. The following network elements are included: Mobility Management Entity (MME): is a control plane function entity for temporarily storing user data. The server is responsible for managing and storing the UE context (such as UE/user identity, mobility management state, user security parameters, etc.), assigning a temporary identifier to the user, and when the UE is camped in the 5 tracking area or the network is responsible for The user is authenticated, and all non-access stratum messages between the MME and the UE are processed; the paging in the SAE is triggered; the monthly service gateway (Serving GW): the gateway is a user plane entity, responsible for user plane data Route processing, terminating the downlink data of the UE in idle state. Manage and store the SAE bearer context of the UE, such as IP bearer service parameters and network internal routing information. It is a 4 seed point of the internal user plane of the 3GPP system. A user can only have one Serving GW at a time;

PDN GW: Packet data network gateway, responsible for the gateway function of the UE to access the PDN, is the mobility anchor of 3GPP and non-3GPP access systems. Users can access multiple PDN GWs at the same time. In addition, the SAE system also allows users to access from traditional Universal Mobile Telecommunications System (UMTS). The network element SGSN in the traditional UMTS can access the Serving GW. At this time, the Serving GW is an anchor point of the user plane in the UMTS and the SAE. In addition, there is also an interface between the SGSN and the MME for providing an interface function similar to the SGSN in the UMTS system. In the area covered by both the SAE system and the UMTS system, when in the idle state, the user can alternately select the access technology in the two systems according to the strength of the signal, thereby causing a large amount of over-the-air signaling. To this end, a technique called Signaling free is currently being researched to avoid or reduce the signaling of air interfaces when users alternately select access technologies. The principle is to allow the user to register in both the SAE and UMTS systems, so that when the user selects the already registered system, the registration process does not need to be initiated again, thereby reducing the over-the-air signaling. However, when the user is in an idle state, The access system is changed without triggering the registration process, so the core network may not know which access system the user is currently in. Therefore, if downlink data arrives, paging must be performed simultaneously in both systems. In order to trigger paging in UMTS, a tunnel for transferring user data is required between the SGSN and the Serving GW. When the next 4 data arrives at the Serving GW, the Serving GW determines that the user is in an idle state. On the one hand, the MME is directly notified to the MME to initiate paging, and the downlink data can be directly sent to the SGSN through the tunnel, thereby triggering the SGSN to initiate the MME in the UMTS. call. Figure 2 shows the flow of this paging. As shown in FIG. 2, the paging includes the following processing: Step 201: The Serving GW receives the downlink data packet from the existing bearer. Step 202: The Serving GW determines, according to the saved information, that the user is currently in an idle state; Step 203, Serving GW The MME is notified to page the user in the SAE. Step 204: The MME stores a current Tracking Area (TA) list, and the MME sends a paging request to all e-Nodes where the TAs are located, e-Node B. Paging the user in the air interface; Step 205, the Serving GW sends the received downlink data (possibly the first data packet) to the SGSN through the existing tunnel; Step 206, the SGSN determines that the user is in an idle state, and is currently present to the user. The radio network controller (RNC) is located to initiate a paging request. Step 207, after receiving the paging request, the user returns a paging response to the current access system, starts to access and establish a bearer, and the Serving GW is established. The downlink data is sent to the UE. As mentioned above, Serving GW is a user-facing monthly gateway, when the user moves ^ (矣,

The MME may reselect the Serving GW according to the location of the e-Node B. When the Serving GW changes, the MME in the current protocol does not notify the relevant SGSN of the change, so that the SGSN cannot create a tunnel to the new Serving GW. Therefore, in the idle state, downlink data cannot be sent from the SGSN side to the new Serving GW, causing the Signaling Free mechanism to fail. Therefore, there is a need to provide a solution to this problem. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a main object of the present invention is to provide a method for establishing a tunnel of an SGSN to a serving gateway. According to an embodiment of the present invention, a method for establishing a tunnel of an SGSN to a serving gateway is provided. The method includes: the mobility management entity notifies the SGSN that the service gateway changes, and notifies the address information of the new serving gateway; the SGSN initiates the establishment of the seven-load request to the new monthly gateway; The SGSN returns to establish a bearer response. The SGSN requests the new serving gateway to establish a user plane tunnel by establishing a bearer request. The bearer request carries the address information of the SGSN and the user plane tunnel ID. Before returning to establish the load response, the new moon service gateway assigns the user plane tunnel ID and carries the assigned user plane tunnel ID in the setup 7 load response. In addition, the mobility management entity notifies during the tracking area update process in the idle state; or performs notification during the handover process in the connected state. Specifically, in the case where the user moves from the source mobility management entity to the destination mobility management entity, the destination mobility management entity notifies, or the source mobility management entity forwards the notification from the destination mobility management entity to the SGSN. Moreover, both the source mobility management entity and the SGSN support the Signaling Free mechanism. In addition, the setup request may be an update PDP context request, and the setup response may be an update PDP context response. Through the above technical solution of the present invention, the effectiveness of the Signaling Free mechanism in the idle state can be guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are set to illustrate,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, In the drawings: FIG. 1 is a schematic diagram of a SAE architecture according to the related art; FIG. 2 is a paging flowchart of Signaling Free technology according to the related art; FIG. 3 is a tunnel establishment of an SGSN to Serving GW according to an embodiment of the present invention; FIG. 4 is a signaling flowchart of a method for establishing a tunnel of an SGSN to a Serving GW according to an embodiment of the present invention; FIG. 5 is a method for establishing a tunnel of an SGSN to a Serving GW according to an embodiment of the present invention; Signaling flowchart of processing example 1; FIG. 6 is a diagram of a tunnel of an SGSN to a Serving GW tunnel according to an embodiment of the present invention. FIG. 7 is a signaling flowchart of a processing example 3 of a method for establishing a tunnel of an SGSN to a Serving GW according to an embodiment of the present invention; and FIG. 8 is an SGSN to Serving according to an embodiment of the present invention. Signaling flowchart of the processing example 4 of the method for establishing the tunnel of the GW. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The solution provided in the embodiments of the present invention can solve the above problems in the related art. When the mobility management entity (MME) discovers that the serving gateway (Serving GW) changes, the SGSN is notified, and the address information of the new Serving GW is notified to the SGSN, so that the SGSN can establish a tunnel to the new Serving GW, thereby making Signaling Free The mechanism can be effective. The embodiments of the present invention are described in detail below with reference to the accompanying drawings, in which: FIG. In this embodiment, a method for establishing a tunnel of an SGSN to a Serving GW is provided. As shown in FIG. 3, the method for establishing a tunnel of the SGSN to the Serving GW according to the present embodiment includes: Step S302: The MME notifies the SGSN that the Serving GW changes, and notifies the address information of the new Serving GW (corresponding to the figure, 4) Step 401, the notification message); Step S304, the SGSN initiates a setup request to the new Serving GW, where the setup request is used to request to establish a user plane tunnel (corresponding to step 402 in FIG. 4, establishing a bearer request); S306. In response to establishing the bearer request, the new Serving GW saves related information (for example, address information and tunnel information of the SGSN), allocates a user plane tunnel ID, and returns a setup response to the SGSN (corresponding to step 403 in FIG. 4, establishing 7^ loaded response). The address request carries the address information of the SGSN and the user plane tunnel ID. The user plane tunnel ID that carries the assignment of the new moon service gateway is established in the bearer response. Specifically, the MME may notify during the tracking area (TA) update process in the idle state; or notify during the handover process in the connected state. When the user moves from the source MME to the destination MME, the destination MME notifies, or the source MME searches for the notification from the destination MME to the SGSN. The source MME and the SGSN both support the Signaling Free mechanism (this process will be described in detail later). In addition, the bearer request is established to update the PDP context request, and the bearer response is established to update the PDP context response. Figure 4 shows a signalling flow diagram for the method. Steps 401, 402, and 403 in FIG. 4 correspond to step S302, step S304, and step S306 in FIG. 3, respectively, and the description thereof will not be repeated here. Through the above processing, the tunnel between the SGSN and the new Serving GW is successfully established. At this point, the downstream data packet can arrive at the SGSN from the tunnel and trigger the paging procedure in UMTS, see step 205 in FIG. Embodiments of the present invention will be described below with reference to examples. Example 1 In this example, it is assumed that the user in the idle mode moves from the UMTS coverage area to the S AE coverage area, as shown in FIG. 5, in the TA update process in this case, the Serving GW ό 变过程 process includes the following Processing: Step 501: When the UE finds that the current SAE signal is better than the UMTS signal, and the current TA is not registered, the UE initiates a TA update request to the network, where the user has the original P-TMSI (User Temporary Identity). And the last registered routing area identifier; after receiving the request, the eNodeB forwards the TA update request to the MME where the current TA is located, where the current TA identifier is present; Step 502: After receiving the destination MME, according to the previous registration The routing area derives the last registered SGSN of the user, so as to obtain the context of the user from the SGSN, where the context includes the original Serving GW of the user; Step 503: The destination MME initiates an authentication process according to the requirement; Step 504: The destination MME determines whether the original Serving GW can continue to be used, and if it can be used, keeps the original Serving GW unchanged; if not, it cannot be used. It is determined to select a new Serving GW; Step 505: After successful authentication, MME returns an SGSN Context object acquisition response message, therefore, return to the user if the SGSN, and on the need for re-authentication data to the HSS acquired; Step 506: The destination MME requests the new Serving GW to allocate resources and establish a bearer process. Step 507: The process in which the destination MME requests user data from the HSS and updates the user location information in the HSS. Step 508: If the destination MME selects a new Serving GW, and The destination MME and the source SGSN both support the Signaling Free mechanism, and the destination MME sends a notification message of the Serving GW change to the source SGSN, where the changed Serving GW identifier and the address information of the new Serving GW are included. Optionally, in step 505, The destination MME notifies the source SGSN of the identifier of the Serving GW change and the address information of the new Serving GW, so that the above step 508 is unnecessary. Step 509: After receiving the notification (the notification is a notification message in step 508 or step 505), the source SGSN sends an update PDP context request to the new Serving GW, where the IP address of the SGSN and the allocated tunnel information are included; Step 510 After receiving the request, the new Serving GW saves the IP address of the SGSN and the tunnel information, allocates its own tunnel information, and returns an update PDP context response to the SGSN, with the tunnel information allocated by the Serving GW (ie, through step 509). And step 510, a new tunnel is established between the source SGSN and the new Serving GW; Step 511: The destination MME re-allocates the S-TMSI, and returns an S-TMSI re-allocation message to the UE, where the returned message carries the S - TMSI and current TA; Step 512: In response to the return message in step 511, the UE saves the S-TMSI and the current TA and returns a TMSI reallocation response. In the example 1, if the destination MME decides to continue to use the original Serving GW in step 504, steps 508 to 510 are not performed, and steps 511 and 512 are directly performed. Example 2 In this example, assuming that a user in idle mode moves within the SAE coverage area, the instance is substantially similar to instance 1, except that the SGSN is not acting as a source node. As shown in FIG. 6, in the TA update process in this case, the change process of the Serving GW includes the following processing: Step 601: The UE finds that the current TA is not registered, and initiates a TA update request to the network. The message, the request message carries the user's original S-TMSI and the last registered TA list; after receiving the request message, the eNodeB forwards the TA update request message to the MME where the current TA is located, and attaches the current TA to the message. Step 602: After receiving the destination MME, the source MME that is last registered by the user is derived according to the last registered TA, so that the context of the user is obtained from the SGSN, where the context includes the original Serving GW of the user and the The address information of the SGSN is registered, and includes an identifier indicating whether the SGSN supports the capability of the Signaling Free. Step 603: The destination MME initiates an authentication process according to the requirement. Step 604: Similar to the foregoing step 504, the destination MME determines whether the original MME can continue to use the original Some Serving GW, if it can be used, keeps the original Serving GW unchanged; if it cannot be used, it decides to select a new Serving GW; Step 605: Same as step 505 above, after the authentication succeeds, the destination MME Returns the SGSN context get response message, therefore, if the user returns to the SGSN again, it needs to re-authenticate and get the number to the HSS. Step 606: Similar to step 506 above, the destination MME requests the new Serving GW to allocate resources and establish a bearer process. Step 607: Similar to step 507 above, the destination MME requests user data from the HSS and updates the user location information in the HSS. step 608: If the destination MME selects a new Serving GW, and the source MME and SGSN are registered at the same time support the Signaling Free Mode mechanism, shellfish ¹ J purpose MME to initiate a notification message to the SGSN Serving GW change, which with Serving GW? The identifier of the change and the address information of the new Serving GW, where the address information of the SGSN is obtained from the original MME in step 602; optionally, in step 605, the response message is obtained using the context, or a new one is used. The destination MME notifies the source MME of the identifier of the Serving GW change and the address information of the new Serving GW; after receiving the notification, the source MME determines that the simultaneously registered SGSN supports Signaling Free, and then initiates a notification of the Serving GW change to the SGSN. The notification message carries a new message of the Serving GW; Step 609, after receiving the notification, the SGSN sends an update PDP to the new Serving GW. The following request, where the request carries the IP address of the SGSN and the allocated tunnel information; Step 610, after receiving the request, the new Serving GW saves the IP address of the SGSN and the tunnel information, allocates its own tunnel information, and sends the tunnel information to the SGSN. Returning to the update PDP context response, with the tunnel information allocated by the Serving GW (ie, a new tunnel is established between the source SGSN and the new Serving GW through steps 609 and 610); Step 611: Same as step 511, the destination MME Redistributing the S-TMSI and returning the S-TMSI reallocation message to the UE with the S-TMSI and the current TA; Step 612: In response to the return message in step 611, the UE saves the S-TMSI and the current TA , and return TMSI to redistribute the response. Similarly, in this example, if the destination MME decides to continue using the original in step 604

Serving GW, it is not necessary to perform steps 608 ~ 610, and directly perform steps 611 and 612. Example 3 Figure 7 shows the processing of the Serving GW change process during the handover from UMTS to SAE in the active mode. As shown in FIG. 7, the method includes the following steps: Step 701: The source RNC sends a handover request message to the source SGSN according to the signal measurement, where the request message carries the information of the destination TA. Step 702: The source SGSN according to the destination TA in the request message Information, find the destination MME, and send a handover request to the MME, where the information of the destination TA and the location information of the source Serving GW are included; Step 703: After receiving the request, the destination MME selects the destination eNodeB according to the information of the target cell, and Determine whether the original Serving GW can continue to use, if not continue to use, select a new Serving GW; Step 704: The destination MME requests the new Serving GW to allocate bearer resources; After the destination Serving GW allocates the bearer resources, the allocated users The face resource information is returned to the MME; Step 705: The destination MME initiates a handover request to the destination eNodeB, and the destination Serving

The GW's username resource 4 is the eNodeB; after the destination eNodeB allocates the bearer resource and the air interface radio resource, it returns a destination MME handover response message with the eNodeB in the response message. The allocated resource information and the air interface radio resource information (ie, the resources of the handover destination are successfully reserved through steps 704 and 705); Step 706: The destination ΜΜΕ returns the source SGSN handover response, where the air interface allocated by the destination eNodeB is allocated. Radio resource information; Step 707: The source SGSN sends a handover command message to the source RNC, where the air interface radio resource information is allocated by the destination eNodeB. Step 708: The source RNC commands the UE to start the handover. Step 709: The terminal allocates the air interface according to the destination eNodeB. The resource information is switched to the destination eNodeB. Step 710: The destination eNodeB reports the handover completion message to the destination MME 4. Step 711: The destination MME sends a handover complete message to the source SGSN, where the message carries an indication of whether the Serving GW changes, if Serving The GW changes, and further carries the address information of the new Serving GW; optionally, the indication of whether the Serving GW changes and the address information of the Serving GW may also be brought to the source SGSN in step 706. Step 712: The source SGSN returns a destination MME handover complete response message. Step 713: The source SGSN sends an update PDP context request to the new Serving GW, where the IP address of the SGSN and the allocated tunnel information are included. Step 714, the new Serving GW receives After updating the PDP context request, the SGSN's IP address and tunnel information are saved, its own tunnel information is allocated, and an update PDP context response is returned to the SGSN with the tunnel information assigned by the Serving GW (ie, by step 714 and Step 715: A new tunnel is established between the source SGSN and the new Serving GW. Step 715: The source SGSN initiates a resource release request to the source RNC. Step 716: After the source RNC releases the related resource, the source RNC sends a resource release response to the source SGSN. In this example, in step 703, if the destination MME determines to continue to use the original

Serving GW, then does not perform steps 713 and 714. Example 4 Figure 8 shows the processing of the Serving GW change process in SAE internal switching in active mode. This example is similar to the previous example 3, except that the SGSN is not the source node of the handover. As shown in FIG. 8, the method includes the following steps: Step 801: The source eNodeB initiates a handover request message to the source MME according to the signal measurement, where the request message carries the information of the destination TA. Step 802: The source MME according to the destination in the request message The information of the TA, finds the destination MME, and then sends a handover request to the MME, where the request carries the information of the destination TA and the location information of the source Serving GW, and the information of the SGSN that is simultaneously registered; Step 803: The destination MME receives the handover After the request, the destination eNodeB is selected according to the information of the target cell; then it is determined whether the original Serving GW can be used again, and if it cannot be used, the new Serving GW is selected; Step 804: The destination MME requests the new Serving GW to allocate the bearer resource, and After the destination Serving GW allocates the ^7- load resource, the allocated user plane resource information is returned to the ΜΜΕ; Step 805: The destination 发起 initiates the handover request to the destination eNodeB, and the destination Serving

The GW user name resource information is sent to the destination eNodeB, and after the destination eNodeB allocates the bearer resource and the air interface radio resource, the destination MME handover response message is returned, where the eNodeB allocates the bearer resource information and the air interface radio resource information (ie, through step 804 and Step 805: The resource of the handover destination is successfully reserved. Step 806: The destination MME returns a source MME handover response message with the air interface radio resource information allocated by the destination eNodeB. Step 807: The source MME initiates a handover command message to the source eNodeB. And the source eNodeB instructs the UE to start the handover. Step 809: The terminal switches to the destination eNodeB according to the air interface radio resource information allocated by the destination eNodeB. Step 810: The destination eNodeB goes to the destination MME. Sending a handover complete message; Step 811: The destination MME sends a handover complete message to the source MME, where the message carries Does the Serving GW change the indication if Serving GW? The variator further carries the address information of the new Serving GW; optionally, the indication of whether the Serving GW changes and the address information of the new Serving GW may also be brought to the source MME in step 806. Step 812: The source MME returns a destination MME handover complete response message. Step 813: If the Serving GW changes, and the SGSN supports the Signaling Free mechanism, the source MME sends a notification message to the SGSN, where the notification message carries the address information of the new Serving GW. Optionally, the destination MME may also directly send a notification message to the SGSN, where the address information of the SGSN may be learned from the source MME in the above step 802. Step 814: After receiving the notification message, the SGSN sends the message to the new Serving GW. Updating the PDP context request, with the IP address of the SGSN and the allocated tunnel information; Step 815, after receiving the update PDP context request, the new Serving GW saves the IP address of the SGSN and the tunnel information, and allocates its own tunnel information, and Returning an update PDP context response to the SGSN with tunnel information assigned by the Serving GW (ie, a new tunnel is established between the source SGSN and the new Serving GW through steps 814 and 815); Step 816: Source MME to source eNodeB Initiating a resource release request; Step 817: The source eNodeB releases the related resource, and then sends a resource release response to the source MME. Similarly, in step 803, if the destination MME determines to continue to use the original Serving GW, it is not necessary to perform step 813. , 814, and 815. In summary, with the solution of the present invention, when the Serving GW changes, the SGSN can re-establish the tunnel to the new Serving GW, thereby ensuring the validity of the Signaling Free mechanism in the idle state. The idea of the present invention can also be applied to the case where the SGSN reselects a Serving GW, and the SGSN notifies the MME to re-establish the connection to the Serving GW, thereby ensuring that the Signaling Free mechanism is valid in the idle state. The preferred embodiment of the invention is not intended to limit the invention, and various modifications and changes can be made thereto without departing from the spirit and scope of the invention. Improvements and the like should be included in the scope of the present invention.

Claims

Claim

A method for establishing a tunnel of a SGSN to a serving gateway, comprising:

The mobility management entity notifies the SGSN that the service gateway changes, and notifies the address information of the SGSN new month service gateway;

The SGSN initiates a bearer setup request to the new serving gateway;

The crescent service gateway returns a setup response to the SGSN.

The method for establishing a tunnel according to claim 1, wherein the establishing a bearer request carries address information of the SGSN and a user plane tunnel ID.

The method for establishing a tunnel according to claim 1, wherein the establishing a bearer response carries a user plane tunnel ID allocated by the crescent service gateway.

The method for establishing a tunnel according to any one of claims 1 to 3, wherein the SGSN requests the new service gateway to establish a user plane tunnel by using the setup request; The credential gateway assigns a user plane tunnel ID before the response is loaded.

The method for establishing a tunnel according to claim 1, wherein the mobility management entity performs the notification in a 3-tracking area update process in an idle state; or in a handover process in a connected state. The notification.

6. The method for establishing a tunnel according to claim 5, wherein the notification is performed by the destination mobility management entity or moved by the source when the user moves from the source mobility management entity to the destination mobility management entity. The management entity sends the notification monument from the destination mobility management entity to the SGSN.

The method for establishing a tunnel according to claim 6, wherein the source mobility management entity and the SGSN both support a Signaling Free mechanism.

The method for establishing a tunnel according to claim 1, wherein the establishing a bearer request is an update PDP context request, and the setup load response is an update PDP context response.