CN101448245B - Method for home network IMS domain to obtain UE access information - Google Patents

Abstract

The invention provides a method for a home network IMS domain to obtain UE access information. The method comprises the steps as follows: access information about that UE is accessed to a visitor network is stored in HSS in advance; the HSS receives a request message of access-request information of S-CSCF from the home network IMS domain; and the HSS feeds back a response message to the S-CSCF, wherein, access information is carried. The invention ensures that the home network IMS domain can obtain the access information of UE, thereby being capable of selecting a proper media route mode for UE roaming.

Description

Method for obtaining UE access information in the IMS domain of the home network

technical field

The present invention relates to the communication field, in particular, to a method for acquiring UE (User Equipment, User Equipment) access information in an IMS (IP Multimedia Subsystem, IP Multimedia Subsystem) domain of a home network. the

Background technique

IMS is the core of the new-generation communication network. Its notable feature is that it adopts the Session Initiation Protocol (SIP) system, communication has nothing to do with access, and can have a variety of media service control functions and bearer capabilities. Session separation, application and service separation, business and network separation, and mobile network and Internet business integration and other capabilities, the proposal of IMS conforms to the development trend of communication network integration. the

Figure 1 shows a block diagram of a conventional IMS architecture. in:

User equipment 101 represents the terminal equipment used by the user;

The call session control function (Call Session Control Function, referred to as CSCF) is the core network element that controls the session process, including: proxy call session control function entity (Proxy-CSCF, referred to as P-CSCF) 102, inquiry call session control function entity (Interrogating -CSCF, referred to as I-CSCF) 103, serving call session control function entity (Serving-CSCF, referred to as S-CSCF) 104;

Home Subscriber Server (Home Subscriber Server, referred to as HSS) 105 is the main storage server of all data related to users and servers in the IMS;

Application Server (AS for short) 106 is a network element providing value-added multimedia services. the

Among the various network elements shown in Figure 1, the UE is connected to the P-CSCF through the Gm interface; the P-CSCF, I-CSCF, and S-CSCF are interconnected through the Mw interface; the HSS is connected to the I-CSCF through the Cx interface , S-CSCF, and the AS through the Sh interface; the S-CSCF is connected to the AS through the ISC (IMS service control, IMS service control) interface. the

With the development of flat network architecture and the emergence of various high-speed broadband mobile access methods, the mobile communication network has proposed the next generation of LTE/SAE (Long term Evolution/System Architecture Evolution, long-term evolution/system architecture evolution). Architectural concepts, including enabling the evolved wireless communication system to provide higher transmission rates, shorter transmission delays, and lower costs, while supporting mobility between access systems within 3GPP (Third Generation Partnership Project) , and the mobility between the 3GPP access system and the non-3GPP access system, etc. At the same time, LTE/SAE will also serve as an access method in the IMS domain, which will promote the evolution and development of the IMS architecture. the

Figure 2 is a roaming scenario proposed by 3GPP. In this case, the UE accesses the network architecture of the IMS service provider network through the SAE access network. The SAE access network is located in the visited domain and provides the underlying access service. The IMS service network is located in the home domain. the

In Figure 2, the corresponding network elements of the SAE network are:

E-UTRAN (Evolved UTRAN, Evolved Universal Terrestrial Radio Access Network): Evolved radio access network is the next generation radio access network, which can provide higher uplink and downlink rates, lower transmission delay and more reliability wireless transmission. The main network entity of E-UTRN is eNodeB (evolved base station). the

MME (Mobility Management Entity, Mobility Management Entity): The control plane functional entity is responsible for managing and storing UE context (such as UE/user identity, mobility management status, user security parameters, etc.), and assigning temporary identifiers to users. When UE It is responsible for authenticating the user when residing in the tracking area or the network. the

SAE GW (SAE Gateway): User plane functional entity, user plane data routing processing, divided into two SAE GWs: Serving GW (Serving Gateway) and PDN GW (Packet Data Gateway, P-GW). Serving GW (S-GW for short) is the mobility anchor point between the SAE system and the traditional 3GPP system and the mobility anchor point between E-UTRAN. PDN GW: It is the ingress gateway of Packed Data Network (PDN). Its functions include terminating the downlink data of the UE in the idle state; initiating paging when the downlink data sent to the UE arrives; managing and storing The context of the UE, such as IP bearer service parameters and internal network routing information. the

Existing 2G/3G mobile networks include:

Wireless includes 2G GERAN (GSM/EDGE Radio Access Network, GSM/EDGE wireless access network, GSM refers to the Global System for Mobile Communications, EGDG is GSM with enhanced data rate) and 3G UTRAN (Universal Terrestrial Radio Access Network, Universal Terrestrial Wireless Access network), the core network includes circuit domain (CS) network element MSC (Mobile Switch Center, mobile switching center) and packet domain network element serving GPRS (General Packet Radio Service) support node (Serving GPRS SupportNode, referred to as SGSN), where MSC provides circuit voice service, circuit data service and short message service, and SGSN is connected to SAE GW in LTE/SAE to provide packet domain service. the

IMS business network includes:

A home subscriber server (Home Subscriber Server, HSS for short) manages data in the CS domain, packet domain (PS) and IMS domain. Policy and Charging Rules Function (Policy and Charging Rules Function, referred to as PCRF) is a function point for controlling media connection, media flow, and performing charging, etc., and belongs to a part of the PCC (Policy and Charging Control, Policy and Charging Control) functional architecture. S-CSCF and P-CSCF are important nodes in the process management of IMS signaling to realize the control and routing of IMS signaling. the

UE can not only access the IMS domain through LTE/SAE, but also access the IMS network through 2G and 3G PS networks (ie GERAN/UTRAN and SGSN in the figure), enjoy IMS services, and also access 2G and 3G CS network, enjoy CS services such as voice services. the

In the context of SAE research, in order to minimize media detours between networks, save network bandwidth, and provide high-quality user experience, 3GPP proposes to allow media routing to The method of direct transfer from the visited network to the home network without detour can effectively avoid the triangular routing problem of media detour to the home network caused by the adoption of mobile IP technology. the

FIG. 3A illustrates the triangular routing problem of the media detour to the home network brought about by using the mobile IP technology in the roaming scenario. As shown in FIG. 3A , since the mobile IP technology is adopted at both UE signaling level and media level, the IP address assigned by the home network is used, but actually the UE is currently located in the visited network. Therefore, according to routing requirements, all media streams destined for the UE need to be sent to the home network first, and then sent to the care-of address of the UE on the visited network through a tunnel on the IP gateway of the home network, and then forwarded to the UE on the visited network. The IP gateway in the figure is responsible for allocating IP addresses to UEs and controlling the routing of media streams. the

In view of the situation in Figure 3A where the media detours to the home network, the 3GPP organization proposes an improved solution as shown in Figure 3B. In this scenario, when the UE uses Mobile IP technology to roam to the visited network, the visited network assigns it a visiting network. Network IP address: IP-L, and served by a visiting network IP gateway. This solution adopts the method that the signaling path passes through the home network, and the media path is directly transferred from the IP gateway of the visited network to avoid the roundabout route of the media. the

The method for solving media detour routing as shown in FIG. 3B is called by 3GPP. That is, after the UE roams to the visited network, the visited network establishes a visited IP bearer for the UE (that is, allocates the visited IP gateway and the visited IP address), and uses the visited IP bearer to route the media directly without detouring to the visited network. home network. the

Different from the local transfer mode (LBO mode) of media routing, the way 3GPP transfers media routing through the home network is called the home network routing mode (Home Routed, referred to as HR mode), that is, the media routing is transferred through the home network. the

At present, in the research on SAE, there is a reference architecture as shown in Figure 4 for the Local Breakout (LBO) mode. In this architecture, both the local breakout mode of media routing and the LBO mode of media routing are supported. Home network routing mode. the

In Figure 4, there are two access gateways (PDN Gateway, P-GW) of the Packet Data Network (PDN) responsible for IP allocation and media routing control, and one is the PDN GW (Home network PDN GW, referred to as H-PGW), and one is the PDN GW (Visited network PDNGateway, referred to as V-PGW) of the visited network. The H-PGW and the V-PGW serve as the packet data access gateways of the home network and the visited network respectively, and their essence is the IP gateway function described in Figure 3 . At the same time, in the visited network, there is a PCRF (Visited network PCRF, V-PCRF for short) of the visited network. The V-PCRF establishes an effective connection with the PCRF (Home network PCRF, H-PCRF for short) of the home network. As the specific execution agent of H-PCRF, H-PCRF serves as the policy and charging data provider of V-PCRF, and the two coordinate with each other, so that the visited network can control the media flow of the visited network according to the home network policy and charging configuration information. Purpose. the

In this reference architecture, the media route can pass through the H-PGW in the home network routing mode, or pass through the V-PGW in the local transfer-out mode. As for the transmission of IMS signaling, it is routed through the home network (that is, via the H-PGW), so that the home network can conveniently control the routing of the signaling and realize some advanced functions. the

Figure 4 is a typical scenario where both the home network routing mode and the local transfer-out mode can be used. In addition, there is a scenario where only one PDN GW is located in the home network, and this scenario only supports the home network routing mode. And, there is a scenario where there is only one PDN GW in the visited network, and this scenario only supports the local transfer-out mode. the

In order to use the local transfer of the media route, the UE first needs to establish the IP bearer of the visited network on the visited network. FIG. 5 depicts a typical flow chart of a UE roaming to a visited network, accessing an SAE network and establishing an IP bearer. the

The process of UE accessing the SAE access network and establishing the IP bearer of the visited network is as follows:

S501. In order to access the SAE network, the UE initiates a network attachment request to the eNodeB, which carries information such as the identity of the UE, the network access capability of the UE, and an indication to request IP allocation;

S502, the eNodeB selects an MME to serve the UE, and forwards the attach request to the MME, and at the same time carries important information such as the UE identity to the MME;

S503, the MME sends a location update request message to the HSS of the home network, and the message carries the identifier of the MME and the identifier of the UE, so as to inform the UE of the currently accessed area;

S504, the HSS finds out the user data of the UE according to the identifier of the UE, and sends it to the MME. This part of the user data of the UE mainly includes information such as whether to allow access to the access network, the default access point name (Access Point Name, APN for short), bandwidth size, etc. If the HSS decides that the UE uses the home network PDN GW, it also contains the address information of the PDN GW;

S505, the MME receives the user data, checks whether the UE is allowed to access the access network, and returns a user data reception response to the HSS;

In this scenario, if the HSS explicitly returns the PDN GW of the home network, the MME uses the PDN GW as the media routing gateway. If the HSS only indicates the default APN and does not indicate the need to use the PDN GW of the home network, the MME selects the local PDN GW as the media routing gateway in the local network. If the HSS indicates the default APN gateway and indicates to use the PDN GW of the home network, the MME uses the PDN GW discovery mechanism of the home network (DNS domain name server mechanism) to discover the PDN GW of the home network. the

S506, the HSS sends a confirmation location update response to the MME;

S507, the MME selects an S-GW for the UE, and sends it a request for establishing a default bearer. In this request, MME informs S-GW of necessary information: UE identity, MME identity, indication of IP address allocation for UE, default bandwidth information, PDN GW address, etc.;

S508, the S-GW sends a request for establishing a default bearer to the PDN GW. In this request, the S-GW informs the PDN GW of the necessary information: the address of the S-GW, the default bandwidth information, the instruction to assign an IP address to the UE, etc.;

S509, if necessary, the PDN GW requests the PCRF for the policy and charging rules and decision information configured for the UE;

S510, the PDN GW establishes a default bearer according to the policy and charging decision information returned by the PCRF, and returns a default bearer establishment response to the S-GW;

S511, the S-GW sends a default bearer establishment response to the MME;

S512, the MME sends an attach response to the eNodeB, indicating that the UE's request to attach to the network has been received;

S513. The eNodeB sends a voice bearer establishment request message to the UE, requesting the UE to store important information about bearer establishment and open a corresponding port. In this message, carry: bearer network identification (ID), PDN GW address, IP address assigned to UE, bandwidth information, etc.;

S514, the UE sends a voice bearer establishment response to the eNodeB;

S515, the eNodeB notifies the MME that the attachment process is completed;

S516, the MME sends an update bearer request to the S-GW, notifying the identity and address of the eNodeB serving the UE;

S517, the S-GW sends an update bearer response to the MME;

S518, if necessary, the MME sends a location update request to the HSS, notifying the HSS of the address information of the PDN GW serving the UE, and the HSS updates the information. the

This step is used to request the MME to report the PDN GW information to the HSS during the handover process from the 3GPP network to the non-3GPP network, or when the PDN GW allocated by the MME is not indicated by the HSS. the

S519. After receiving the location update request from the MME, the HSS processes the request and returns a location update response. the

After the establishment process of the IP bearer of the visited network as shown in FIG. 5 is completed, correspondingly, there is an IP bearer of the visited network allocated for the UE. The IP bearer information used to identify a UE may include: UE identifier (Subscriber Identifier), UE IP address. A UE may have multiple IP bearers. With these key information, it is possible to distinguish which IP bearers belong to which UE, and which IP bearers belong to which IP address of the UE. Further, according to the access network identifier in the attribute of the IP bearer, which access network the IP bearer is located in can be distinguished. That is, the network can know that the UE is currently located in the visited network according to the access identifier of the UE's current access to the visited network, and can assign an access gateway and an IP address to the UE based on the known current visited network, and judge that the visited network is established for the UE. The local IP bearer of the visited network is specified. the

Through the bearer establishment process similar to that shown in Figure 5, the UE can establish an IP bearer to the home network. After the IP bearer of the home network is established, the UE can discover the P-CSCF in the IMS domain of the home network and perform IMS registration through the IP bearer of the home network. . It needs to be clarified that the process of the UE registering with the IMS domain of the home network may be before the UE establishes the IP bearer of the visited network, or after the UE establishes the IP bearer of the visited network. In addition, the UE may first establish the home network IP bearer and then roam to the visited network, or directly establish the home network IP bearer in the visited network. the

If the UE has established the IP bearer of the visited network and the IP bearer of the home network, and registered in the IMS domain of the home network, the UE can initiate a call or receive a call from other UEs. the

In order to reduce the consumption of network resources, the IMS domain of the home network may require the UE to select an appropriate media routing mode, such as the local forwarding mode, to optimize no routing after receiving a call initiated by the UE or executing a call from the UE. Or when the IMS domain of the home network needs to monitor and measure the media flow, it is necessary to prohibit the UE from using the local transfer mode of the media route. the

Under these requirements, the home network IMS domain needs to make a decision on which media routing mode the UE chooses, and the premise for making a decision is that the home network IMS domain needs to know the summary information of the bearers established by the UE in the home network and the visited network, such as The network identifier, the media gateway identifier (or address), the IP address assigned to the UE, and the like. For the IP bearer of the home network, the IMS registration process is performed by the UE. The IMS domain of the home network already knows the required summary information. However, for the IP bearer of the visited network, since the UE does not carry any information to the IMS of the home network, the IMS of the home network cannot It is known that the UE can adopt the local transfer-out mode of media routing in the visited network, and furthermore, it is impossible to make a media routing mode decision. the

After the UE registers in the IMS home network and roams to the visited network, after the IP bearer for media routing is established in the visited network, there are two paths for the media stream to choose from, one is the home network route and the other is the visited network route. Local outbound route. However, since the signaling path used by the UE uses the IP address of the home network, whether the UE initiates registration with the home network or the UE initiates a call, the IMS home network does not know that the UE has an IP address on the visited network for local media transfer. The path of the outgoing route. That is to say, when the UE initiates a call, the IMS home network cannot realize the selection and control of the media routing path of the UE because the IMS home network does not know that the UE can use the local transfer path of the media route in the visited network, and optimizes the media route. Selected for the purpose of avoiding media routing detours. the

The same situation also occurs in the following scenarios: UE starts on the visited network, discovers and establishes the IP bearer of the home network and the IP bearer of the visited network, and uses the established IP bearer of the home network to register with the IMS home network. Wherein, the process of establishing the IP bearer of the home network by the UE may be before or after establishing the IP bearer of the visited network. the

The flow chart shown in FIG. 6 describes the situation that in the roaming scenario of the present invention, when the UE initiates a call, the IMS domain of the home network cannot implement media routing due to lack of necessary information. the

Before this process is initiated, the network has established the home network IP bearer and the visited network IP bearer for the UE, and the UE has registered in the home network IMS domain using the home network IP. At this time, if the UE initiates a call using the IP address allocated by the home network, in this case, the home network cannot adopt media routing optimization for this situation, that is, it cannot require the media to be transferred locally from the visited network. the

S601, the UE initiates a call request, and the call request is sent to the P-CSCF; the call request includes media negotiation information;

In the call request, the UE uses the IP address assigned by the home network, and the SDP (Session Description Protocol, Session Description Protocol) data contained in it is used to negotiate connection information and media format. In addition, the address used by the UE for negotiating media routing in the SDP data is also the IP address allocated by the home network. the

S602. After receiving the call request from the UE, the P-CSCF extracts and detects the downlink connection information, including: the IP address, port and other information used by the call originator (UE) for media calls;

S603, the P-CSCF forwards the call request to the terminated network, which includes the media negotiation information of the call initiator;

S604, the called end party completes the media negotiation, and returns the media negotiation result; which includes the acceptable media information of the call initiator and the media information that the party can provide;

S605, the P-CSCF extracts and detects the uplink connection information from the received media negotiation result, including: the IP address, port and other information used by the end caller for the media call;

S606, the P-CSCF requests the PCRF for media authorization. In this request, the P-CSCF provides the uplink connection information, downlink connection information, and other necessary information to the PCRF for the PCRF medium to perform authorization checks, so as to perform operations such as policy control and media resource reservation;

S607, the PCRF locally stores the session information of the SIP layer, and associates the information with the session of the IP bearer layer;

S608, the PCRF sends a media authorization response to the P-CSCF, indicating that the authorization has been successful, and operations such as policy control and resource reservation can be performed;

S609, the P-CSCF notifies the call initiator (UE) that the media negotiation has been completed; the UE needs to use the specified IP address and port to send the media stream according to the media negotiation result;

S610, the PCRF interacts with the PCEF to complete the policy control and resource allocation process according to the SIP layer session connection information obtained from the P-CSCF, as well as the policy and charging decision information. the

S611, the UE, the P-CSCF, etc. complete the subsequent session processing procedure. In the follow-up process, the media sent by the call-terminating party to the call-initiating party must be detoured to the home network. the

In the call flow shown in Figure 6, the signaling address used by the UE and the media address used for media negotiation are IP addresses allocated by the home network; therefore, after the session is established, the media route needs to be detoured to the home network. In this scenario, since the home network only knows the information about the UE's access to the home network and cannot know the information about the UE's access to the visited network, it cannot know that the UE can currently use the local transfer mode of media routing, and it is impossible to request The UE adopts the local switch-out mode to optimize media routing, that is, media routing selection cannot be performed. the

After the IP bearer of the visited network shown in FIG. 5 is established, the UE may adopt the local transfer-out mode of the visited network for media routing. However, in this roaming scenario, the IMS home network can only know that the UE has established a signaling and media bearer path of the home network, but does not know that the UE has another path in the visited network for local transfer of media routing. That is to say, the IMS home network considers that the UE can only use the media bearer path established by the home network, but cannot select and use other media bearer paths. the

The actual situation is that the UE has been assigned an optimized media routing path that can be used in the visited network. For the IMS home network, it is necessary to first know that the UE can use the media routing path to be transferred locally in the visited network, and then choose an optimized one that does not violate other Decision factors for media routing patterns. the

From the above analysis, it can be found that in the roaming scenario, in order to be able to decide the media routing mode used by the UE to reduce unnecessary waste of resources, the IMS first needs to know that the UE in the visited network can use the local transfer mode of media routing. In the process of implementing the present invention, the inventors found that in the prior art, the IMS home network lacks a method to obtain the access information of the UE in the visited network, such as the access network identifier, the access gateway identifier, and the visited network IP address. the

Only when the IMS obtains the access information of the UE accessing the visited network through a certain method, can it know that the UE can use the local transfer-out mode of the media routing. Only then can it further decide whether to force the UE to use a specific media routing mode, such as the local transfer-out mode, according to the local policy or user service configuration of the IMS home network, and make the UE adjust the media routing mode according to the instruction. the

Contents of the invention

The present invention aims to provide a method for the IMS domain of the home network to acquire UE access information, so as to solve the problem that the IMS domain of the home network cannot acquire the access information of the UE in the prior art. the

In an embodiment of the present invention, a method for acquiring UE access information in the IMS domain of the home network is provided, including the following steps: pre-store the access information about the UE's access to the visited network in the HSS, wherein the access The information includes the identifier of the user equipment and a combination of one or more of the following: the identifier of the access network of the visited network, the identifier of the access gateway of the visited network, the IP address of the user equipment connected to the visited network; the HSS receives information from the IMS domain of the home network The request message of the S-CSCF requesting access information; the HSS feeds back a response message to the S-CSCF, which carries the access information. the

The method for obtaining user equipment access information in the home network IMS domain of the above embodiment overcomes the problem in the prior art that the home network IMS domain cannot obtain UE access information because the HSS is used to pre-store the UE access information, and further Able to select appropriate media routing mode for UE roaming. the

Description of drawings

The accompanying drawings described here are used to provide a further understanding of the present invention and constitute a part of the application. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations to the present invention. In the attached picture:

Fig. 1 is a schematic diagram of network element entities and their connection relationships related to the present invention in the IMS architecture in the prior art;

Fig. 2 is a schematic diagram of the architecture of accessing the IMS domain of the home network through the SAE access network in the existing roaming scenario, and only describes the scenario where there is an IP bearer in the visited network. the

FIG. 3A is a schematic diagram of a roaming scenario using mobile IP technology in the prior art;

Figure 3B is a schematic diagram of a method for solving media detours proposed by the 3GPP organization in the prior art;

Figure 4 is a schematic diagram of an architecture that simultaneously supports local transfer-out mode and home network routing mode under the SAE architecture and UE roaming in the prior art;

FIG. 5 is a flowchart of a method for establishing an IP bearer in the visited network after the UE roams to the visited network in the prior art;

FIG. 6 is a flowchart of a method for initiating a call with an IP address assigned to the UE by the home network in the case of roaming in the prior art;

FIG. 7 shows a flowchart of a method for obtaining UE access information in the IMS domain of the home network according to an embodiment of the present invention;

FIG. 8 shows a flowchart of a method for establishing a visited network IP bearer by a UE according to a preferred embodiment of the present invention;

Fig. 9 shows a flowchart of a method for the S-CSCF in the IMS domain of the home network to select a media route for the UE according to a preferred embodiment of the present invention. the

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. the

FIG. 7 shows a flowchart of a method for acquiring UE access information in the IMS domain of the home network according to an embodiment of the present invention, including the following steps:

Step S10, pre-store the access information about the UE's access to the visited network in the HSS;

Step S20, the HSS receives a request message requesting access information from the S-CSCF in the IMS domain of the home network;

In step S30, the HSS feeds back a response message to the S-CSCF, which carries access information. the

Because the method uses the HSS to pre-store the access information of the UE, it overcomes the problem in the prior art that the IMS domain of the home network cannot obtain the access information of the UE, and can then select a suitable media routing mode for UE roaming. the

The UE establishes the IP bearer of the visited network in the visited network, establishes the IP bearer of the home network and registers with the IMS home network, so that the UE can use the local transfer mode of media routing or the routing mode of the home network. The above process can be divided into the following three situations:

(1) After the UE establishes an IP bearer in the home network and successfully registers with the IMS home network, it roams to the visited network. At this time, the UE retains the IP bearer of the home network and establishes the IP bearer of the visited network;

(2) The UE starts on the visited network, establishes the IP bearer of the home network and the IP bearer of the visited network, and then uses the established IP bearer of the home network to register with the IMS home network; before or after carrying;

(3) The UE starts up on the visited network, first establishes the IP bearer of the home network, then registers with the IMS home network, and finally establishes the IP bearer of the visited network. the

When the UE establishes the IP bearer of the visited network, after the visited network allocates the PDN GW and IP address for the UE to establish the IP bearer, the MME initiates the location update process to the HSS to actively update the information of the PDN GW and the UE's Key information such as IP address information is sent to the HSS of the home network. the

When the S-CSCF in the IMS domain of the home network receives the call initiated by the UE or directed to the UE, it queries the HSS for the access information of the UE to the visited network, and saves it in the S - Information on the CSCF, judging that the UE can use local forwarding or home network media routing. the

So far, the IMS home network can learn that the UE located in the visited network can use the local transfer-out mode for media communication, then it can perform media routing selection, use the local transfer-out mode or home network routing for media communication, and can also target specific services The UE is forced to use one of two methods for media communication. the

Preferably, step S10 specifically includes: after the UE roams and establishes the IP bearer of the visited network, the MME sends a location update message to the HSS, which carries access information; the HSS obtains the access information from the location update message; the HSS saves the access information . the

Preferably, before the MME sends the location update message to the HSS, it specifically includes: when the UE roams and attaches to the visited network, the MME sends the location update request message to the HSS; the HSS receives the location update request message; the HSS sends the request message to the MME to request the MME to report Instructions for accessing information. the

Preferably, when the S-CSCF receives the call request from the UE or when it knows that the UE initiates IMS registration, it sends a request message to the HSS, requiring the HSS to immediately feed back the access information, and the HSS feeds back the response message to the S-CSCF, which specifically includes: HSS analysis Request message to know the UE to be requested by S-CSCF; HSS retrieves the UE's access information from its pre-stored information; HSS constructs a response message, which carries access information; HSS feeds back the response message to S-CSCF. the

Preferably, when the S-CSCF learns that the UE initiates IMS registration, it sends a request message to the HSS, requiring the HSS to actively notify the S-CSCF of the access information when the access information is updated, and the HSS feeds back the response message to the S-CSCF specifically including: When the HSS receives the updated access information about the UE's access to the visited network from the MME, it actively notifies the S-CSCF of the updated access information. the

Preferably, the method further includes: receiving a call request from the UE; the S-CSCF judges whether the UE can currently use the local transfer-out mode according to the access information; if so, according to the locally saved user service configuration and/or local policy as The UE selects the local transfer-out mode or the home network routing mode in the media routing mode; if it is judged that the local transfer-out mode cannot be used, the S-CSCF selects the home network routing mode for the UE; the S-CSCF notifies the UE of the selected media routing pattern. the

Preferably, the call request is a call request of the UE, and the S-CSCF notifies the UE of the selected media routing mode by sending a 380 message carrying media routing indication information during media negotiation; or the call request is directed to the UE The S-CSCF notifies the UE of the selected media routing mode specifically includes: the S-CSCF forwards the INVITE (invitation) message to the UE, which carries the selected media routing mode. the

Preferably, the access information includes the identifier of the UE and a combination of one or more of the following: the identifier of the access network of the visited network, the identifier of the access gateway of the visited network, the IP address of the UE to access the visited network, and the S-CSCF according to The access information judging whether the UE can currently use the local transfer-out mode specifically includes: the S-CSCF learns that the UE is currently located in the visited network according to the access identifier of the UE's current access to the visited network, and the learned current visited network assigns the UE The access gateway and the IP address know that the visited network has established a local IP bearer of the visited network for the UE. the

Preferably, the method further includes: the S-CSCF sends the access information to the P-CSCF; receiving the call request from the UE; the P-CSCF judges whether the UE can currently use the local transfer-out mode according to the access information; if yes, then Select the local transfer-out mode or the home network routing mode for the UE according to the locally saved user service configuration and/or local policy; if it is judged that the local transfer-out mode cannot be used, the P-CSCF selects the home network route for the UE mode; the P-CSCF notifies the UE of the selected media routing mode. the

Preferably, the call request is a call request of the UE, and the P-CSCF notifies the UE of the selected media routing mode by sending a 380 message carrying media routing indication information during media negotiation; or the call request is directed to the UE The P-CSCF notifies the UE of the selected media routing mode specifically includes: the P-CSCF forwards the INVITE message to the UE, which carries the selected media routing mode. the

Preferably, the access information includes the identifier of the UE and a combination of one or more of the following: the identifier of the access network of the visited network, the identifier of the access gateway of the visited network, the IP address of the UE to access the visited network, and the P-CSCF according to The access information judging whether the UE can currently use the local transfer-out mode specifically includes: the P-CSCF learns that the UE is currently located in the visited network according to the access identifier of the UE's current access to the visited network, and allocates Knowing the access gateway and IP address, the visited network has established the local IP bearer of the visited network for the UE. the

8 and 9 are preferred embodiments of the present invention, which are used to describe how the IMS home network correctly learns the media routing modes that the UE can use in the roaming scenario described in the present invention, and further performs media routing selection. the

Fig. 8 shows a flowchart of a method for UE to establish a visited network IP bearer according to a preferred embodiment of the present invention. This embodiment describes the process in which the UE is located in the visited network, and when the IP bearer of the visited network is established, the access information of the UE accessing the visited network is sent to the HSS of the home network. the

S801. In order to access the SAE network, the UE initiates a network attachment request to the eNodeB, which carries information such as the identity of the UE, the network access capability of the UE, and an indication to request IP allocation;

S802, the eNodeB selects an MME to serve for the UE, and forwards the attach request to the MME, and at the same time carries important information such as the UE's identity to the MME;

S803, the MME sends a location update request message to the HSS of the home network, and the message carries the identifier of the MME and the identifier of the UE, so as to inform the UE of the currently accessed area;

S804, the HSS finds out the user data of the UE according to the identifier of the UE, and sends it to the MME. This part of the user data of the UE mainly includes information such as whether to allow access to the access network, the default access point name (Access Point Name, APN for short), bandwidth size, etc. If the HSS decides that the UE uses the home network PDN GW, it also contains the address information of the PDN GW;

In addition, in the user data sent to the MME, the HSS can carry instructions to inform the MME that the UE is allowed to use the Local Breakout method for media routing, and requires the MME to report the access information of the UE to the visited network to the HSS, specifically including: The network identifier, the access gateway identifier or address (referring to the identifier or address of the PDN GW), the IP address of the UE allocated to the visited network, etc. the

S805, the MME receives the user data, checks whether the UE is allowed to access the access network, and returns a user data reception response to the HSS;

In this scenario, if the HSS explicitly returns the PDN GW of the home network, the MME uses the PDN GW as the media routing gateway. If the HSS only indicates the default APN and does not indicate the need to use the PDN GW of the home network, the MME selects the local PDN GW as the media routing gateway in the local network. If the HSS indicates the default APN gateway and indicates to use the PDN GW of the home network, the MME uses the PDN GW discovery mechanism of the home network (DNS domain name server mechanism) to discover the PDN GW of the home network. the

S806, the HSS sends a confirmation location update response to the MME;

S807, the MME selects an S-GW for the UE, and sends it a request for establishing a default bearer. In this request, MME informs S-GW of necessary information: UE identity, MME identity, indication of IP address allocation for UE, default bandwidth information, PDN GW address, etc.;

S808, the S-GW sends a request for establishing a default bearer to the PDN GW. In this request, the S-GW informs the PDN GW of the necessary information: the address of the S-GW, the default bandwidth information, the instruction to assign an IP address to the UE, etc.;

S809, if necessary, the PDN GW requests the PCRF for the policy and charging rules and decision information configured for the UE;

S810, the PDN GW establishes a default bearer according to the policy and charging decision information returned by the PCRF, and returns a default bearer establishment response to the S-GW;

S811, the S-GW sends a default bearer establishment response to the MME;

S812, the MME sends an attach response to the eNodeB, indicating that the UE's request to attach to the network has been received;

S813, the eNodeB sends a voice bearer establishment request message to the UE, requesting the UE to store important information about bearer establishment, and open a corresponding port. In this message, it carries: bearer network identification (ID), PDN GW address, IP address assigned to UE, bandwidth information, etc.;

S814, the UE sends a voice bearer establishment response to the eNodeB;

S815, the eNodeB notifies the MME that the attachment process is completed;

S816, the MME sends an update bearer request to the S-GW, notifying the identity and address of the eNodeB serving the UE;

S817, the S-GW sends an update bearer response to the MME;

S818. If necessary, the MME sends a location update request to the HSS, notifying the HSS of the address information of the PDN GW serving the UE, and the HSS updates the information. the

According to the instruction given by the HSS in step 804 when sending the user data, the MME is required to report the access information of the UE's access to the visited network. When the MME judges the above situation, it initiates the location update process, and in the location update process, carries the following general information about the UE's access to the visited network: UE ID, network ID, and access gateway ID (here, the PDN GW ID of the UE), the IP address assigned to the UE, and the like. the

S819. After receiving the location update request from the MME, the HSS processes the request and returns a location update response. the

In this step, the HSS simultaneously extracts the access information of the UE to the visited network carried in the message, such as: network identifier, access gateway identifier, IP address assigned to the UE, etc., and stores the data in the UE's related information. In order to provide data for the S-CSCF in the IMS to request the HSS for the access information of the UE to access the visited network in the future. the

In the process shown in Figure 8, the MME requests the MME to report the access information of the UE to the visited network according to the received HSS instruction, and triggers the location update process of PDN GW allocation and IP bearer establishment completion thickness. Furthermore, the MME may also unconditionally execute the location update process shown in step 818 without following the instruction of the HSS, and report the access information of the UE's access to the visited network to the HSS. If the MME performs step 818 unconditionally, then in step 804, the HSS does not need to carry an instruction requiring the MME to report the access information of the UE's access to the visited network. the

Through the process shown in Figure 8, during the process of allocating the PDN GW for the UE and establishing the IP bearer for the UE, the access information of the UE accessing the visited network is successfully saved on the HSS through the location update interaction between the MME and the HSS. Later, if the UE initiates the IMS registration process, the HSS can send the access information of the UE to the visited network to the S-CSCF through the response of the S-CSCF to the HSS requesting data during the registration process. Or, if the UE has registered with the IMS, the S-CSCF may actively query the HSS for the access information of the UE's access to the visited network. the

After the process in Figure 8 is completed, the S-CSCF can make full use of the available access information of the UE to access the visited network. For the call initiated by the UE or the terminal call directed to the UE, according to the local policy or user service configuration, Decide whether to require the UE to adopt the specified media routing mode, and further notify the UE to adopt the specified media routing mode. the

Fig. 9 shows a flowchart of a method for selecting a media route in the IMS domain of the home network according to a preferred embodiment of the present invention. This embodiment describes that when the UE initiates a call or is terminated, the S-CSCF of the IMS home network queries the access information of the UE to the visited network from the HSS, and according to the access information of the home network stored in the UE registration process, Incoming information to determine whether the UE can use the local transfer-out mode of media routing, and further determine whether to use a specific media routing mode for media communication according to local policy, user service configuration and other judging elements. the

In step 901, the S-CSCF receives a terminal call directed to the UE; or the S-CSCF receives a call initiated by the UE. The media negotiation information is carried in the above call termination message and call initiation message;

In step 902, the S-CSCF requests the HSS for the access information of the UE to access the visited network, including: network identifier, access gateway identifier, assigned IP address, and so on. The HSS finds out the relevant information of the UE and returns it to the S-CSCF;

Step 903, the S-CSCF locally saves the access information of the UE to the visited network, and judges whether the UE can currently use the local transfer-out mode of the media routing according to the information stored during the registration process of the UE to the home network;

If the S-CSCF judges that the UE has two IP bearers of the visited network and the home network, it considers that the UE can support both the local transfer-out mode of media routing and the home network routing mode of media routing. the

Step 904, the S-CSCF determines the media routing mode used by the UE according to the user service configuration and/or local policy, and the media routing mode refers to: use the local transfer mode, or use the home network routing mode;

Step 905, if the S-CSCF needs to specify the media routing mode used by the UE, but the current UE is not using the routing mode, notify the UE to use the specified media routing mode. the

If the call process is initiated by the UE, the S-CSCF can send a 380 message to the UE, which is a message requesting the UE to try another service (Alternative Service). The message carries media routing instruction information requiring the UE to initiate a call in a specified mode. the

If the call is a terminal call directed to the UE, the S-CSCF can carry media routing indication information when forwarding the INVITE request to the UE, requiring the UE to perform media communication in a specific media routing mode, or specify the media routing mode used by the UE. Address for media correspondence. the

Only when the S-CSCF needs to specify the media routing mode used by the UE, it needs to be notified through the 380 message (for the UE to initiate the call), or through the media routing information specified in the media negotiation in the INVITE (for the UE to be terminated) The UE uses a specific media routing pattern. If the S-CSCF does not need to be designated, it shall be handled according to the existing procedures. the

Step 906, after the media routing mode negotiation is completed, the S-CSCF continues to process the subsequent session process. the

The method for the S-CSCF shown in Figure 9 to obtain the access information of the UE's access to the visited network is to actively query the HSS for the information when the S-CSCF processes the session. In addition, for how the S-CSCF obtains the access information of the UE accessing the visited network, there are also the following embodiments, and the steps are as follows:

(1) During the IMS registration process of the UE, when the S-CSCF requests user data from the HSS, it also requests the UE to access the access information of the visited network. And further, the S-CSCF can simultaneously subscribe to the change of the access information during the request process;

(2) When the HSS sends user data to the S-CSCF, it also sends the access information of the UE to the visited network to the S-CSCF;

(3) In the subsequent process, if the S-CSCF subscribes to the HSS for the change of the access information of the UE to the visited network, when the MME updates the access information of the UE to the visited network to the HSS, the HSS needs to notify Changes to the information of the S-CSCF. the

In summary, the present invention provides a method for selecting the media routing mode of the UE in the IMS domain of the home network after the UE locates or roams to a certain access network under the LTE/SAE architecture of the next generation mobile communication network (local transfer out or home network routing). mode) is applied to the IMS access network. After the UE roams to the visited network, it can effectively solve the problem that the IMS home network cannot know whether the UE supports the local transfer mode of media routing, and then can select the optimized media for the UE. routing pattern. the

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention. the

Claims (10)

1. A method for obtaining user equipment access information in the home network IMS domain, is characterized in that, comprising the following steps: The access information about the user equipment accessing the visited network is pre-stored in the home user server, wherein the access information includes the identifier of the user equipment and a combination of one or more of the following: the access of the visited network A network identifier, an access gateway identifier of the visited network, and an IP address for the user equipment to access the visited network; The home subscriber server receives a request message requesting the access information from a serving call session control function entity in the home network IMS domain; The home subscriber server feeds back a response message to the serving call session control function entity, which carries the access information; Wherein, when the SCSCF entity learns that the user equipment initiates IMS registration, it sends the request message to the home subscriber server, requesting that the home subscriber server actively Notifying the S-CSCF entity of the access information, the home subscriber server feeding back a response message to the S-CSCF entity specifically includes: When receiving the updated access information about the user equipment accessing the visited network from the mobility management entity, the home user server proactively notifies the serving CSCF entity of the updated access information. input information. 2. The method according to claim 1, wherein the pre-stored access information about the access of the user equipment to the visited network in the home user server specifically includes: After the user equipment roams and establishes a visited network IP bearer, the mobility management entity sends a location update message to the home user server, which carries the access information; The home subscriber server obtains the access information from the location update message; The home user server saves the access information. 3. The method according to claim 2, wherein before the mobility management entity sends the location update message to the home subscriber server, it specifically comprises: When the user equipment roams and attaches to a visited network, the mobility management entity sends a location update request message to the home user server; The home subscriber server receives the location update request message; The home subscriber server sends an indication to the mobility management entity to request the mobility management entity to report the access information. 4. The method according to claim 1, characterized in that, when the serving call session control function entity receives the call request from the user equipment or when it knows that the user equipment initiates IMS registration, it sends to the home The subscriber server sends the request message, requesting the home subscriber server to immediately feed back the access information, and the home subscriber server feeds back a response message to the serving call session control function entity, which specifically includes: The home subscriber server parses the request message to know the user equipment to be requested by the serving CSCF entity; The home subscriber server retrieves the access information of the user equipment from its pre-stored information; The home subscriber server constructs the response message, which carries the access information; The HSS feeds back the reply message to the serving-CSCF entity. 5. The method according to any one of claims 1 to 4, further comprising: receiving a call request from the user equipment; The SCSCF entity determines whether the user equipment can currently use the local transfer-out mode according to the access information; If so, selecting a local transfer-out mode or a home network routing mode in the media routing mode for the user equipment according to the locally saved user service configuration and/or local policy; If it is judged that the local transfer-out mode cannot be used, the SCSCF entity selects a home network routing mode for the user equipment; The serving call session control function entity informs the user equipment of the selected media routing mode. 6. The method of claim 5, wherein, The call request is a call origination request of the user equipment, and the serving call session control function entity notifies the user equipment of the selected one by sending a 380 message carrying media routing indication information during media negotiation. media routing pattern; or The call request is a call termination request directed to the UE, and the SCSCF entity notifying the UE of the selected media routing mode specifically includes: the SCSCF entity notifying the UE of the selected media routing mode. The user equipment forwards the invitation message, which carries the selected media routing mode. 7. The method according to claim 5, wherein the SCSCF entity judging whether the user equipment can currently use the local transfer-out mode according to the access information specifically includes: The SCSCF entity learns that the user equipment is currently located in the visited network according to the access network identifier of the user equipment currently accessed to the visited network, and that the learned current visited network allocates an access network for the user equipment. Knowing that the visited network has established a visited network local IP bearer for the user equipment through the ingress gateway identifier and IP address. 8. The method according to any one of claims 1 to 4, further comprising: The serving-CSCF entity sends the access information to a proxy-CSCF entity; receiving a call request from the user equipment; The proxy-call session control function entity judges whether the user equipment can currently use the local transfer-out mode according to the access information; If so, selecting a local transfer-out mode or a home network routing mode in the media routing mode for the user equipment according to the locally saved user service configuration and/or local policy; If it is judged that the local transfer-out mode cannot be used, the proxy-call session control function entity selects a home network routing mode for the user equipment; The Proxy-Call Session Control Function entity notifies the user equipment of the selected media routing mode. 9. The method of claim 8, wherein The call request is a call origination request of the user equipment, and the proxy call session control function entity notifies the user equipment of the selected one by sending a 380 message carrying media routing indication information during media negotiation. media routing pattern; or The call request is a terminal call request directed to the user equipment, and the proxy-CSCF entity notifying the user equipment of the selected media routing mode specifically includes: the proxy-CSCF entity notifying the user equipment of the selected media routing mode. The user equipment forwards the invitation message, which carries the selected media routing mode. 10. The method according to claim 8, wherein the PCSCF entity judging whether the user equipment can currently use the local transfer-out mode according to the access information specifically includes: The proxy call session control function entity learns that the user equipment is currently located in the visited network according to the access network identifier that the user equipment currently accesses to the visited network, and allocates the user equipment to the user equipment according to the learned current visited network. Access the gateway identifier and IP address to learn that the visited network has established a visited network local IP bearer for the user equipment.

Images