CN107409303B

CN107409303B - Determine voice session support on PS when both roaming models are supported, home routing and local breakout

Info

Publication number: CN107409303B
Application number: CN201580077342.6A
Authority: CN
Inventors: R.凯勒; P.丹内布罗
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2015-03-03
Filing date: 2015-03-03
Publication date: 2021-05-07
Anticipated expiration: 2035-03-03
Also published as: CN107409303A; WO2016138940A1

Abstract

This application relates to a concept that has been named S8 Home Routing, where a control node in a visited PLMN will set a Voice over PS support indication standardized by 3GPP TS 23.401. However, in the prior art, if the UE has subscribed to the IMS roaming service via the home PLMN, the control node receives no indication from the home PLMN. Therefore, when the local breakout is not allowed as indicated by the parameter "V-PLMN address allowed" is "not allowed", then the UE does not know whether it can expect a successful IMS voice-over-PS session. This application solves this problem by introducing a new parameter "H-PLMN Address Allow", which is similar to the already known "V-PLMN Address Allow" parameter, which is contained in the HSS (117) in the secondary PLMN (110) ) is provided into the subscription information of the controlling nodes (103, 104) in the visited PLMN (100).

Description

Determining voice over PS session support when two roaming models are supported, home routing and local breakout

Technical Field

The present invention relates to a method and an arrangement for providing a service to a user equipment, UE, via a packet data network gateway, PDN GW, wherein the UE is served by a visited public land mobile network, V-PLMN, and wherein the UE has a subscription with a home public land mobile network, H-PLMN.

Background

In a typical cellular system, also referred to as a wireless communication network, a Public Land Mobile Network (PLMN) or a network, wireless terminals, also referred to as mobile stations and/or user equipment Units (UEs), communicate with radio network nodes in a Radio Access Network (RAN). The UE may be a mobile terminal through which a subscriber may access services provided by the operator's Core Network (CN) and services outside the operator's RAN and the network to which the CN provides access. The radio access network covers a geographical area which is divided into cell areas, with each cell area being served by a base station, e.g. a Radio Base Station (RBS), which in some radio access networks is also referred to as evolved nodeb (enb), eNode-B, B node or base station. The base station communicates over an air interface operating on radio frequencies with user equipment within range of the base station. The RANs may implement different Radio Access Technologies (RATs), such as Long Term Evolution (LTE), global system for mobile communications (GSM), Universal Mobile Telecommunications System (UMTS), (worldwide interoperability for microwave access (WiMAX), and so on.

In a roaming scenario, a UE with a subscription to an operator of a home public land mobile network (H-PLMN) is served by a visited public land mobile network (V-PLMN). If the UE intends to use a service in the V-PLMN, like a voice over IMS service, it may send a request to a control node in the V-PLMN. The control node has to forward this request to a Packet Data Network (PDN) gateway which connects the public land mobile network to a service providing network, which may be an operator Internet Protocol (IP) service network, such as an IP Multimedia Subsystem (IMS). The control node may select a PDN gateway (PDN GW) for this particular UE based on a roaming agreement between the operator of the V-PLMN and the operator of the H-PLMN. In addition, the control node may have some further indication to select the PDN GW.

The PDN GW selection function is mentioned in section 4.3.8.1 by the 3GPP standard TS 23.401 V13.1.0. According to this standard, the PDN GW selection function allocates the PDN GW that will provide PDN connectivity for 3GPP access. This function uses subscriber information provided by a Home Subscriber Server (HSS) in the H-PLMN. The PDN subscription context provided by the HSS contains at least the identity of the PDN GW and the Access Point Name (APN) or APN and an indication of whether allocation of the PDN GW from the V-PLMN is allowed for this APN. The PDN GW selection function derives a PDN GW identity from the V-PLMN if the HSS provides a PDN subscription context that allows allocation of the PDN GW from the V-PLMN, and optionally a control node in the V-PLMN is configured to know that the V-PLMN has a suitable roaming agreement with the UE's H-PLMN. Deriving a PDN GW identity from the H-PLMN using the APN if the PDN GW identity cannot be derived or if the subscription does not allow the PDN GW to be allocated from the V-PLMN.

The standard GSMA PRD ir.92V 8.0 has specified that only the roaming model with the PDN GW in V-PLMN is applied for roaming UEs served by V-PLMN and having a subscription to H-PLMN. This roaming model is described in GSMA PRD ir.65V 8.0 and GSMA PRD ir.88V 9.0. Therefore, the control node of the V-PLMN needs to know that local breakout (breakout) is allowed for roaming UEs in order to be able to set the IMS voice session support indication on PS. The GSMA PRD ir.92 standard has specified that when IMS roaming with V-PLMN is enabled, the HSS in the H-PLMN sets a "V-PLMN address allowed" (VPAA) parameter, where the specific subscriber is an IMS subscriber that requires a PDN GW in the V-PLMN as described in GSMA PRD ir.88.

Thus, the home operator can use VPAA to indicate that the subscriber is an IMS subscriber authorized for VoLTE roaming by allowing the V-PLMN to select a PDN GW in the V-PLMN and thereby allowing the V-PLMN to send an IMS voice session support indication over PS to indicate that the UE can expect to successfully perform VoLTE services. It is also possible that the home operator can use VPAA to indicate that the IMS subscriber is not authorized for VoLTE roaming by denying the V-PLMN to select the PDN GW in the V-PLMN and thereby preventing the V-PLMN from sending the IMS voice session support indication of PS. VPAA is the only indication that the H-PLMN can use to direct (steer) V-PLMN behavior while still allowing the UE to connect to the IMS APN. If the VPAA received by the control node of the V-PLMN from the HSS in the H-PLMN is set to "allowed", the control node does not know whether the PDN GW 105 in the V-PLMN should be selected, even if the roaming model uses the PDN GW in the H-PLMN. This concept has been named S8HR (S8 home route). If VPAA is set to "not allowed", the control node has to select the PDN GW in the H-PLMN. In this case, there is no indication from the H-PLMN if the UE has subscribed to IMS roaming services and can expect a successful IMS over PS voice session. That is, if the control node in the V-PLMN would set a voice over PS session support indication to the UE, there is no indication from the H-PLMN. This may result in the control node indicating to the UE voice over PS session support even if the subscriber is not an IMS subscriber for voice and the UE will unnecessarily establish a PDN connection and attempt to register in IMS. It may also be possible that this may result in a roaming UE having a roaming subscription and may not receive a voice over PS session support indication and therefore will not use VoLTE when roaming.

Disclosure of Invention

It is an object of the present invention to improve service provisioning to roaming user equipment. This object is achieved by the independent claims. Advantageous embodiments are described in the dependent claims.

According to a first aspect, a method of providing a service to a user equipment, UE, via a packet data network gateway, PDN GW, is provided. The UE is served by a visited public land mobile network V-PLMN and the UE has a subscription with a home public land mobile network H-PLMN. The method comprises the following steps: providing, by a register in the H-PLMN, an indication of H-PLMN permission indicating whether a PDN GW in the H-PLMN is authorized to be selected for the UE to perform the service. The method comprises the further steps of: providing, to the UE, an indication of whether the UE can expect successful performance of the service based on the H-PLMN allowed indication.

According to a second aspect, there is provided a control node in a visited public land mobile network, V-PLMN, serving a user equipment, UE, wherein the UE has a subscription with a home public land mobile network, H-PLMN. The control node is adapted to: receiving a request for service from the UE; and receiving an indication of H-PLMN permission indicating whether a packet data network gateway, PDN GW, in the H-PLMN is authorized to be selected for the UE to perform the service. The control node is further adapted to provide an indication to the UE whether the UE can expect successful execution of the service based on the H-PLMN allowed indication.

According to a third aspect, a method in a control node of a visited public land mobile network, V-PLMN, serving a user equipment, UE, wherein the UE has a subscription with a home public land mobile network, H-PLMN, is provided. The method comprises the following steps: receiving a request for service from the UE; receiving an indication of H-PLMN permission indicating whether a packet data network gateway, PDN GW, in the H-PLMN is authorized to be selected for the UE to perform the service; and providing an indication to the UE of whether the UE can expect successful performance of the service based on the H-PLMN allowed indication.

According to a fourth aspect, there is provided a register in a home public land mobile network, H-PLMN, storing subscription data for a user equipment, UE, wherein the UE has a subscription with the H-PLMN. The register is adapted to: storing an indication of H-PLMN permission indicating whether a packet data network gateway, PDN GW, in the H-PLMN is authorized to be selected for the UE to perform the service. The register is further adapted to provide an indication of the H-PLMN permission to a control node of a visited PLMN (V-PLMN) serving the UE.

According to a fifth aspect, there is provided a method in a register of a home public land mobile network, H-PLMN, storing subscription data of a user equipment, UE, wherein the UE has a subscription with the H-PLMN. The method comprises the following steps: storing an indication of H-PLMN permission indicating whether a packet data network gateway, PDN GW, in the H-PLMN is authorized to be selected for the UE to perform the service; and providing an indication of the H-PLMN permission to a control node of a visited PLMN (V-PLMN) serving the UE.

The invention also relates to a computer program comprising portions of software code or instructions for implementing a method as described above when operated by at least one respective processing unit of a user device and a recipient device. The computer program can be stored on a computer readable medium. The computer readable medium can be permanent or rewritable memory within or external to the user device or the recipient device. The respective computer program can also be delivered as a sequence of signals to a user device or a recipient device, e.g. via a cable or a wireless link.

Drawings

The invention will be further described with reference to exemplary embodiments shown in the drawings, in which:

figure 1 shows a block diagram illustrating an embodiment of a roaming architecture for LTE/EPC;

FIG. 2 shows a flow chart illustrating one embodiment of a method according to the present invention;

FIG. 3 shows a flow chart illustrating one embodiment of a method according to the present invention;

fig. 4 shows a block diagram illustrating an embodiment of a control node;

FIG. 5 illustrates a block diagram that shows an embodiment of a register.

Detailed Description

In the following description, for purposes of explanation and not limitation, specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. For example, although the exemplary embodiments are described in connection with LTE/EPC standard terminology to illustrate the present invention, they are equally applicable to other kinds of mobile communication systems. Also, the present invention may be practiced in any network to which a mobile user may attach.

Those skilled in the art will further appreciate that the functions explained herein below may be implemented using hardware circuitry, software components, or combinations thereof. The software components may use Application Specific Integrated Circuits (ASICs) and/or Digital Signal Processors (DSPs) in conjunction with a programmed microprocessor or general purpose computer. It will also be apparent that when the present invention is described as a method, it may also be embodied in a computer processor and a memory coupled to the processor, where the memory is encoded with one or more programs that, when executed by the processor, perform the method.

Within the context of the present application, the term "user equipment" (UE) refers to a device that a person uses for his or her personal communication, for example. It can be a telephone type device such as a telephone or a SIP phone, a cellular phone, a mobile station, a cordless phone, or a personal digital assistant type device like a laptop, a notebook, a notepad equipped with a wireless data connection. The UE may also be associated with non-humans, like animals, plants, or even machines. The UE may be equipped with a SIM (subscriber identity module) that includes unique identities such as IMSI (international mobile subscriber identity) and/or TMSI (temporary mobile subscriber identity) associated with the subscriber using the UE. The presence of a SIM within the UE uniquely customizes the UE with the subscription of the subscriber.

Within the context of the present application, the term "communication network" or abbreviated "network" may particularly denote a collection of nodes or entities, related transmission links, and associated management, required for running a service, such as a telephony service or a packet transmission service. Depending on the service, different node types or entities may be utilized to implement the service. The network operator owns the communication network and provides the implemented services to its subscribers. Typical examples of communication networks are radio access networks (such as 2G, GSM, 3G, WCDMA, CDMA, LTE, WLAN, Wi-Fi), mobile backhaul networks, or core networks such as IMS, CS core, PS core.

Within the context of the present application, the term "control node" refers to a node of a communication network that mainly performs control procedures for services and sessions or calls of subscribers of the communication network. The term generally refers to those entities of the communication network that handle control plane, subscriber data, services, or signaling traffic associated with user traffic in the communication network. In a packet core network, the control node may be an MME (mobility management entity), SGSN (serving gateway support node), P-CSCF (proxy call state control function), S-CSCF (serving CSCF), or TAS (telephony application server) node.

Within the context of the present application, a PDN Gateway (PGW) or PDN GW is a node that provides connectivity from a UE to external packet data networks by being the exit and entry points of traffic for the UE. A UE may have simultaneous connectivity with more than one PGW in order to access multiple PDNs. The PGW performs policy enforcement, packet filtering for each user, charging support, lawful interception and packet screening.

Within the context of the present application, a request for service may refer to an initial attach or independent PDN connectivity request, i.e., a request for service to a particular PDN.

The illustration in the drawings is schematically. In different figures, similar or identical elements are provided with the same reference signs or with reference signs differing from each other in the leading digit.

As shown in fig. 1, the Long Term Evolution (LTE)/Evolved Packet Core (EPC) architecture supports Packet Switched (PS) roaming, and is similar to that deployed for global system for mobile communications (GSM) and Wideband Code Division Multiple Access (WCDMA).

Fig. 1 is a block diagram illustrating an embodiment of an architecture of a communication network including a home public land mobile network (H-PLMN)110 and a visited public land mobile network (V-PLMN) 100. The H-PLMN 110 refers to a network that is registered as the home of the User Equipment (UE) 101. The UE101 may roam between the H-PLMN 110 and the V-PLMN 100, for example. The V-PLMN 100 includes an evolved UMTS terrestrial radio Access network (E-UTRAN)102 on the access side and an Evolved Packet Core (EPC) on the core side. The E-UTRAN 102 is the air interface for LTE. The E-UTRAN 102 includes a base station, such as, for example, an eNodeB (not shown), which interfaces with user equipment. For illustration purposes only, the H-PLMN 110 and V-PLMN 100 are separated by a dotted line.

The H-PLMN 110 includes a Home Subscriber Server (HSS)117, a home PDN GW 115. The PDN GW 115 in the H-PLMN 110 and the PDN GW 105 in the V-PLMN 100 are connected to

packet data networks

106, 116, the

packet data networks

106, 116 providing operator Internet Protocol (IP) services such as IP Multimedia Subsystem (IMS), PSS, etc. IMS is an architectural framework for delivering Internet Protocol (IP) multimedia services like voice over IMS or voice over IP.

The HSS 117 is a database comprising subscription data and authentication data. The HSS 117 interfaces to a Mobility Management Entity (MME)103 in the V-PLMN 100 via an S6a interface. The MME 103 is for example responsible for selecting the appropriate PDN GW 105,115 for the user equipment data session. The PDN GW 115 in the H-PLMN 115 is a node in the H-PLMN 110 that allocates and reserves an IP address to the user equipment. The PDN GW 115 also takes care of policy and charging enforcement.

The V-PLMN 100 further comprises a Serving Gateway (SGW)104 that routes and forwards user data packets while also acting as a mobility anchor for the user plane during inter-eNB handover and as an anchor for mobility between LTE and other 3GPP technologies. The SGW 104 is connected to the E-UTRAN 102 of the V-PLMN 100 via the S1-U interface. In addition, the SGW 104 in the V-PLMN 100 is connected to the PDN GW 115 in the H-PLMN 110 via the S8 interface. The S8 interface is a public land mobile inter-network reference point that provides the user and control planes between the SGW 104 in the V-PLMN 100 and the PDN GW 115 in the H-PLMN 110. The V-PLMN 100 further comprises a PDN GW 105. The PDN GW 105 in the V-PLMN 100 also takes care of policy and charging enforcement.

A UE101 adapted to use voice over IP services in IMS gets an indication of whether it can expect successful voice over IP voice session placement and receive voice over IP services and calls from an indication of voice over IP session support over Packet Switched (PS).

Figure 2 illustrates a flow diagram showing one embodiment of a method of providing service to a UE101 served by a V-PLMN. The UE101 is served by a V-PLMN when the V-PLMN is providing access to a mobile communication network or PLMN. The UE101 is connected to an access network of the V-PLMN 100, which is controlled by a core network node 103 of the V-PLMN 100. In addition, the UE101 has a subscription with the H-PLMN 110. In a first step 210, an indication of H-PLMN allowance, indicating whether the PDN GW 115 in the H-PLMN 110 is authorized to be selected for the UE101 in order to perform a service. The service may be a voice over IP Multimedia Subsystem (IMS) service or any other kind of service that can be provided by the IMS to a UE101 having a subscription to the IMS. The voice over IMS service may also be denoted as voice over LTE (VoLTE) service or voice over IP (VoIP) service. The indication of the H-PLMN permission may be provided by a register 117 in the H-PLMN 110. The register 117 in the H-PLMN 110 may be a Home Subscriber Server (HSS). Additionally, the H-PLMN allowed indication may be encapsulated in a PDN subscription context including subscriber data according to 3GPP TS 23.401 V13.1.0 provided by register 117 in H-PLMN 110 for UE 101. The indication may be provided to a control node 103 in the V-PLMN 100, which can be an MME in the EPC network.

In a next step 230, an indication is made to determine whether to provide the UE101 with an indication whether the UE101 can expect a successful execution of the service based on the indication allowed by the H-PLMN. If the register 117 has not provided an indication of H-PLMN enablement, then no indication of successful execution of the service may be provided to the UE 101. In another embodiment, the determination of whether to provide the UE101 with an indication of whether the UE101 can expect successful execution of the service may depend on an additional indicator of the register.

In a next step 240, an indication is provided to the UE101 of whether the UE101 can expect successful execution of the service. If the UE101 receives this indicator of successful execution of the service, the UE101 will attempt to establish the service. For example, if the UE101 has requested VoIMS service and the UE101 receives an indicator indicating that the UE can expect successful execution of the service, the UE101 will attempt to establish a VoIMS session. If the UE101 receives an indication indicating that the UE101 cannot expect successful performance of the service, the UE101 does not continue to establish the VoIMS connection, but instead attempts to establish a normal CS voice session over another CS network that may also cover the same area in which the UE101 is currently located.

According to a further embodiment in fig. 3, two indications are provided by register 117 in H-PLMN 110. In a first step 310, an indication of H-PLMN allowability is provided, indicating whether the PDN GW 115 in the H-PLMN 110 is authorized to be selected for the UE101 in order to perform the service. In a next step 320, an indication of V-PLMN permission is provided indicating whether the PDN GW 105 in the V-PLMN 100 is authorized to be selected for the UE101 in order to perform the service. The indication of V-PLMN permission may be a V-PLMN address permission (VPAA) parameter. Both indications may be encapsulated in the PDN subscription context provided by register 117 in H-PLMN 110. These two indications may be provided to the control node 103 in the V-PLMN 100, which can be an MME in the EPC network.

In a next step 330, a decision is made based on the indication of H-PLMN permission and the indication of V-PLMN permission. This decision may also be performed in the control node 103 of the V-PLMN 100. As a result of the determination, an indication is provided to the UE101 in step 340 of whether the UE101 can expect successful execution of the service.

For the decision when sending the UE101 an indication whether the UE101 can expect a successful execution of the requested service, the control node 103 can now take the permission settings in the H-PLMN 110 and the V-PLMN 100 into account. The control node 103 thus has an overview of the grant conditions in its own network 100 and in the H-PLMN 110 of the UE 101.

According to an embodiment of the invention, an indication is provided to the UE101 indicating: the UE101 cannot expect successful execution of the service if the indication of V-PLMN permission and the indication of H-PLMN permission indicate that the PDN GW 105 in the V-PLMN 100 and the PDN GW 115 in the H-PLMN 110 are not authorized to be selected for the UE101 to execute the service. This may be done by sending a negative indication to the UE101 or by not sending any indication to it at all.

According to another embodiment of the invention, an indication may be provided to the UE101 indicating that the UE101 can expect successful execution of the service if at least one of the V-PLMN allowed indication or the H-PLMN allowed indication indicates that the PDN GW 105 in the V-PLMN 100 or the PDN GW 115 in the H-PLMN 110 is authorized to be selected for the UE101 to execute the service. Successful execution of the service can be expected by the UE101 if the UE101 is authorized to use at least one or both of the PDN GWs 105,115 in the V-PLMN 100 and H-PLMN 110.

According to another embodiment of the invention, the selection of the PDN GW 105,115 for routing the service request to the selected PDN GW 105,115 is performed in a prioritized order based on the indication of H-PLMN permission and the indication of V-PLMN permission. The selection of the PDN GW 105,115 may be performed in the control node 103 in the V-PLMN 100. This control node 103 may be an MME or SGSN or any other control node in the PS core network responsible for selecting a gateway for service execution. After the control node 103 in the V-PLMN 100 has decided whether the PDN GW 105 in the V-PLMN 100 or the PDN GW 115 in the H-PLMN 110 should be used to perform the requested service, then the control node 103 may add an operator identifier to the Access Point Name (APN) already provided by the UE101 or HSS 117. If the PDN GW 115 in the H-PLMN 110 has been selected, the control node 103 requests an address from a data name server DNS in its own network (V-PLMN) 100. The DNS in the V-PLMN 100 may query the DNS in the H-PLMN 110 to obtain the address of the PDN GW 115 in the H-PLMN 110 to route the request to the received address. Selecting the PDN GW 05,115 in prioritized order means that the control node 103 determines the values of the H-PLMN allowed indication and the V-PLMN allowed indication in prioritized order. According to one embodiment, the selection of the PDN GW 105,115 to route the service request to the selected PDN GW 105,115 is performed by: if the indication of H-PLMN permission indicates that the PDN GW 115 in the H-PLMN 110 is authorized to be selected for the UE101 to perform the service, then the PDN GW 115 in the H-PLMN 110 is selected first; and if this indication is negative, selecting the PDN GW 105 in the V-PLMN 100 if the V-PLMN allowed indication indicates that the PDN GW 105 in the V-PLMN 100 is authorized to be selected for the UE101 to perform the service.

According to another embodiment, the selection of the PDN GW 105,115 to route the service request to the selected PDN GW 105,115 is performed by: if the indication of V-PLMN permission indicates that the PDN GW 105 in the V-PLMN 100 is authorized to be selected for the UE101 to perform the service, then first selecting the PDN GW 105 in the V-PLMN 100; and if this indication is negative, selecting the PDN GW 115 in the H-PLMN 110 if the H-PLMN allowed indication indicates that the PDN GW 115 in the H-PLMN 110 is authorized to be selected for the UE101 to perform the service. If the indication of V-PLMN permission and the indication of H-PLMN permission both indicate that the PDN GW 115 in H-PLMN 110 and the PDN GW 105 in V-PLMN 100 are authorized to be selected for the UE101 to perform a service, the prioritized selection of PDN GWs 105,115 may result in different gateways, depending on the PLMN permission indicator that has been determined first. By defining the priority order, it is possible to set preferences in the V-PLMN 100 on how to handle roaming UEs 101. This preference may also be based on a roaming agreement for the UE101 between the V-PLMN 100 and the H-PLMN 110. It may also be possible to set any other preference for selecting the PDN GW 105,115 in the V-PLMN or the H-PLMN in the control node 103.

According to another embodiment of the invention, the preference in the V-PLMN 100 for selecting the PDN GW 105,115 in the V-PLMN 100 or in the H-PLMN 110 may also be based on the access point name APN provided by the UE 101. This APN may comprise additional information or may be a completely different and specific APN like ("IMS home routing" or "IMS-LBO").

The preferences in V-PLMN 100 for selecting the PDN GW 105,115 may be different if the APN is already provided by the UE101 or if the IMS APN is an APN used as a default APN for the UE 101. As an advantage, the UE101 may be able to direct the selection of the PDN GW 105,115 in the V-PLMN 100 or the H-PLMN 110.

According to another embodiment of the invention, if both indicators (H-PLMN allowed and V-PLMN allowed) indicate that both PDN GWs 105,115 in H-PLMN 110 and in V-PLMN 100 are authorized to be selected for UE101 to perform a service, then the non-selected PDN GWs 105,115 (non-preferred PDN GWs) in V-PLMN 100 or H-PLMN 110 can be defined as standby (fallback) gateways, which can be selected if the preferred PDN GWs 105,115 that have been selected based on preferences or other parameters cannot provide the requested service to UE 101. The non-selected PDN GW 105,115 may be used as a backup PDN GW 105,115 that can replace the previously selected PDN GW 105,115 very quickly if the previously selected PDN GW 105,115 is no longer accessible, e.g. in overload conditions or due to a break in the network. An advantage of having a standby PDN GW 105,115 is that there is no need to repeatedly determine the service providing the PDN GW 105,115, provided that the selected PDN GW 105,115 is not able to provide the service. The control node can just switch to the

standby PDN GW

105, 115.

Table 1 shows a decision matrix that may be stored in the control node of the V-PLMN 100:

TABLE 1

If both indicators indicate that the PDN GWs 105,115 in the V-PLMN 100 and H-PLMN 110 are not allowed (last row), there will be no indicator to the UE101 that the UE101 of the UE101 can expect to successfully perform the requested service. Nonetheless, the service request will still be routed to the H-PLMN 110 to maintain the UE101 registered in the IMS using other services in the H-PLMN 110, even if the particular requested service is not available. If the requested service is a voice over IMS service and both indicators are negative, the UE101 can establish a voice session using the CS connection.

Fig. 4 shows a block diagram illustrating an embodiment of a control node 400 in a V-PLMN according to an embodiment of the present invention. The control node 400 may be an MMS or SGSN node. The control node 400 is adapted to serve a UE with a subscription to the H-PLMN via the access network. The control node 400 comprises a receiver 410 adapted to receive a request for service from a UE. This request may be encapsulated in another message, or it may be a specific service request. The request is received via a node in an access network currently serving the UE. The receiver 410 is further adapted to receive an indication of H-PLMN allowance indicating whether a PDN GW in the H-PLMN is authorized to be selected for the UE to perform a service. The indication of the H-PLMN permission may be encapsulated in a PDN subscription context received from a register in the H-PLMN via the core network. From this H-PLMN allowed indication the control node 400 knows whether the operator has authorized the use of the PDN GW in the UE's H-PLMN. The control node 400 comprises a processor 420, the processor 420 being adapted to make the following decision based on the received indication of H-PLMN permission and the service request: an indication is provided to the UE via transmitter 430 whether the UE can expect successful execution of the requested service.

In a further embodiment of the invention, the control node 400 is further adapted to receive, via the receiver 410, an indication of V-PLMN permission indicating whether a PDN GW in the V-PLMN is authorized to be selected for the UE to perform the service. The processor 420 will make a decision regarding sending an indicator to the UE whether the UE can expect successful execution of the service, where this decision is now additionally based on the indication of V-PLMN permission.

According to an embodiment of the present invention, if at least one of the indication of V-PLMN permission or the indication of H-PLMN permission indicates that the PDN GW in V-PLMN or the PDN GW in H-PLMN is authorized to be selected for the UE to perform the service, the processor 420 will obtain the following result: an indication is sent to the UE via transmitter 430 indicating that the UE can expect successful performance of the service.

According to an embodiment of the present invention, if the indication of V-PLMN permission and the indication of H-PLMN permission indicate that the PDN GW in V-PLMN and the PDN GW in H-PLMN are not authorized to be selected for the UE to perform the service, the processor 420 will obtain the following result: no indication is sent to the UE or an indication is sent to the UE via transmitter 430 indicating that the UE cannot expect successful performance of the service.

According to another embodiment of the invention, the control node 400 is further adapted to: if the indication of V-PLMN permission indicates that a PDN GW in a V-PLMN is authorized to be selected for the UE to perform the service and the indication of H-PLMN permission indicates that a PDN GW in an H-PLMN is not authorized to be selected for the UE to perform the service, the service request is routed to the PDN GW of the V-PLMN via transmitter 420.

According to another embodiment of the invention, the control node 400 is further adapted to: routing the service request to the PDN GW of the H-PLMN if the H-PLMN allowed indication indicates that the PDN GW in the H-PLMN is authorized to be selected for the UE to perform the service and the V-PLMN allowed indicator indicates that the PDN GW in the V-PLMN is not authorized to be selected for the UE to perform the service.

According to another embodiment of the invention, the control node 400 is further adapted to: if the indication of H-PLMN permission and the indication of V-PLMN permission indicate that the PDN GW in the V-PLMN and in the H-PLMN is authorized to be selected for the UE to perform the service, the service request is routed to the PDN GW in the H-PLMN or the PDN GW in the V-PLMN according to the preference indication stored in the memory 440.

It is to be understood that the structure shown in fig. 4 is merely schematic and that the control node 400 may in fact comprise further components which have not been shown for the sake of brevity, e.g. further interfaces. For example, multiple network interfaces can be provided that are configured to allow communication with other nodes of different types. Also, it is to be understood that the storage entity may contain further types of program code modules, which have not been shown.

Fig. 5 shows a block diagram illustrating an embodiment of a register 500 in the H-PLMN of a UE. The register 500 may be a home subscriber server HSS, or any other storage means comprising subscription data for UEs. The register 500 includes: a memory 540 adapted to store subscription data 550 for a number of UEs having a subscription to the operator of the H-PLMN in which the register 500 is located. Part of the subscription data 550 for the UE is an indication of H-PLMN permission, which indicates whether the PDN GW in the H-PLMN is authorized to be selected for the UE to perform a service. The register 500 further includes: a receiver 510 adapted to receive a request from a control node for providing an indication of H-PLMN allowance to the requesting control node. The register 500 further includes: a processor adapted to control the memory 540 in the register 500. The register 500 further includes: a transmitter 530 adapted to provide an indication of H-PLMN allowance to a control node of a visited PLMN (V-PLMN) currently serving the UE. This H-PLMN allowed indication may also be provided to the control node in the V-PLMN via the transmitter in the PDN subscription context.

According to another embodiment of the invention, the register 500 may also include in the UE data 550 an indication of V-PLMN permission indicating whether the PDN GW in the V-PLMN is authorized to be selected for the UE to perform a service. This indication may also be provided to the control node in the V-PLMN via transmitter 530 using the PDN subscription context.

It is to be understood that the structure shown in fig. 5 is merely schematic and that register 500 may in fact contain further components which have not been shown for the sake of brevity, such as further interfaces. For example, multiple network interfaces can be provided that are configured to allow communication with other nodes of different types. Also, it is to be understood that the storage entity may contain further types of program code modules, which have not been shown.

Furthermore, it is to be understood that the above concepts may be implemented by using software designed accordingly to be executed by one or more processors of an existing device, or by using dedicated device hardware. Also, the nodes described herein may be implemented by a single device or by multiple devices (e.g., a cloud or system of devices operating in coordination).

The invention also relates to a computer program comprising software code or instruction portions for implementing the above described method when operated by at least one respective processing unit of a user device and a recipient device. The computer program can be stored on a computer readable medium. The computer readable medium can be permanent or rewritable memory within or external to the user device or the recipient device. The respective computer program can also be delivered as a sequence of signals to a user device or a recipient device, e.g. via a cable or a wireless link.

Claims

1. A method of providing a service to a user equipment, UE, (101) via a packet data network gateway, PDN, GW, (105,115), wherein the UE (101) is served by a visited public land mobile network, V-PLMN, (100) and wherein the UE (101) has a subscription with a home public land mobile network, H-PLMN (110), the method comprising the steps of:

-providing (210), by a register (117,500) in the H-PLMN (100), an indication of H-PLMN permission indicating whether a PDN GW (115) in the H-PLMN (110) is authorized to be selected for the UE (101) for performing the service; and

-providing (240) an indication to the UE (101) whether the UE (101) can expect a successful execution of the service based on the indication allowed by the H-PLMN,

wherein the method further comprises the steps of: providing, by the register (117,500) in the H-PLMN (110) of the UE (101), an indication of V-PLMN permission indicating whether a PDN GW (105) in the V-PLMN (100) is authorized to be selected for the UE (101) to perform the service, and wherein the step of providing the indication to the UE (101) of whether the UE (101) can expect successful performance of the service is further based on the indication of V-PLMN permission, and wherein the indication to the UE (101) indicates: the UE (101) can expect a successful execution of the service if at least one of the indication of V-PLMN permission or indication of H-PLMN permission indicates that the PDN GW (105,115) in the V-PLMN (100) or in the H-PLMN (110) is authorized to be selected for the UE (101) in order to execute the service.

2. The method of claim 1, wherein the V-PLMN allowed indication and the H-PLMN allowed indication are encapsulated in a PDN subscription context provided by the register in the H-PLMN (110) for the UE (101).

3. The method of claim 1, wherein the selection of the PDN GW (105,115) to route the service request to the selected PDN GW (105,115) is performed in a prioritized order based on the indication of H-PLMN permission and the indication of V-PLMN permission.

4. A method according to claim 3, wherein performing said selection of said PDN GW (105,115) for routing said service request to the selected PDN GW (105,115) is by: -first selecting a PDN GW (115) in the H-PLMN (110) if the indication that the H-PLMN allows indicates that the PDN GW (115) in the H-PLMN (110) is authorized to be selected for the UE (101) for performing the service; and if this indication is negative, selecting a PDN GW (105) in the V-PLMN (100) if the indication allowed by the V-PLMN indicates that the PDN GW (105) in the V-PLMN (100) is authorized to be selected for the UE (101) for performing the service.

5. A method according to claim 3, wherein performing said selection of said PDN GW (105,115) for routing said service request to the selected PDN GW (105,115) is by: -if the indication of V-PLMN permission indicates that a PDN GW (105) in the V-PLMN (100) is authorized to be selected for the UE (101) for performing the service, first selecting a PDN GW (105) in the V-PLMN (100); and if this indication is negative, selecting a PDN GW (115) in the H-PLMN (110) if the indication allowed by the H-PLMN indicates that the PDN GW (115) in the H-PLMN (110) is authorized to be selected for the UE (101) for performing the service.

6. The method of claim 1, wherein the indication to the UE (101) indicates that: the UE (101) cannot expect a successful execution of the service if the indication of V-PLMN permission and the indication of H-PLMN permission indicate that the PDN GW (105,115) in the V-PLMN (100) and the H-PLMN (110) are not authorized to be selected for the UE (101) to execute the service.

7. The method according to claim 1, wherein the service is a voice over IP multimedia subsystem, IMS, service, and wherein the indication to the UE (101) is a voice over PS session support indication.

8. The method of claim 1, wherein the indication of V-PLMN permission is a VPAA parameter of V-PLMN address permission.

9. The method of claim 1 or 2, wherein the selection of a serving PDN GW (105,115) is based on preferences in the V-PLMN (100) if the indication of V-PLMN permission and the indication of H-PLMN permission indicate that a PDN GW (115) in the H-PLMN (110) and a PDN GW (105) in the V-PLMN (100) are authorized to be selected for the UE (101) to perform the service.

10. The method of claim 9, wherein the preference in the V-PLMN (100) is based on an access point name, APN, provided by the UE (101).

11. The method of claim 1 or 2, wherein if the indication of V-PLMN permission and the indication of H-PLMN permission indicate that a PDN GW (115) in the H-PLMN (110) and a PDN GW (105) in the V-PLMN (100) are authorized to be selected for the UE (101) for performing the service, a PDN-GW (105,115) in a non-preferred PLMN is selected as a backup PDN GW (105,115) in case the serving PDN GW (105,115) in a preferred PLMN is not able to serve the UE (101).

12. A control node (103,400) in a visited public land mobile network, V-PLMN (100), serving a user equipment, UE, (101), wherein the UE (101) has a subscription with a home public land mobile network, H-PLMN (110), and wherein the control node (103,400) is adapted to:

-receiving a request for service from the UE (101);

-receiving an indication of H-PLMN allowance indicating whether a packet data network gateway, PDN GW, (115) in the H-PLMN (110) is authorized to be selected for the UE (101) for performing the service; and

-providing an indication to the UE (101) whether the UE (101) can expect a successful execution of the service based on the indication allowed by the H-PLMN,

wherein the control node (103,400) is further adapted to receive an indication of V-PLMN permission indicating whether a PDN GW (105) in the V-PLMN (100) is authorized to be selected for the UE (101) for performing the service, and wherein the indication of whether the UE (101) to the UE (101) can expect successful performance of the service is further based on the indication of V-PLMN permission, and wherein the indication to the UE (101) indicates: the UE (101) can expect a successful execution of the service if at least one of the indication of V-PLMN permission or indication of H-PLMN permission indicates that the PDN GW (105) in the V-PLMN (100) or the PDN GW (115) in the H-PLMN (110) is authorized to be selected for the UE (101) to execute the service.

13. The controlling node (103,400) of claim 12, wherein the indication to the UE (101) indicates that: the UE (101) cannot expect a successful execution of the service if the indication of V-PLMN permission and the indication of H-PLMN permission do not authorize the PDN GW (105,115) in the V-PLMN (100) and in the H-PLMN (110) to be selected for the UE (101) for executing the service.

14. The control node (103,400) of claim 12, wherein the control node (103,400) is further adapted to: routing the service request to a PDN GW (105) in the V-PLMN (100) if the indication of V-PLMN permission indicates that the PDN GW (105) in the V-PLMN (100) is authorized to be selected for the UE (101) to perform the service and the indication of H-PLMN permission indicates that the PDN GW (115) in the H-PLMN (110) is not authorized to be selected for the UE (101) to perform the service.

15. The control node (103,400) of claim 12, wherein the control node (103,400) is further adapted to: routing the service request to the PDN GW (115) of the H-PLMN (110) if the indication of H-PLMN permission indicates that the PDN GW (115) of the H-PLMN (110) is authorized to be selected for the UE (101) to perform the service and the indicator of V-PLMN permission indicates that the PDN GW (105) of the V-PLMN (100) is not authorized to be selected for the UE (101) to perform the service.

16. The control node (103,400) of claim 12, wherein the control node (103,400) is further adapted to: routing the service request to a PDN GW (115) in the H-PLMN (110) or a PDN GW (105) in the V-PLMN (100) according to a preference indication stored in the control node (103,400) if the indication of H-PLMN permission and the indication of V-PLMN permission indicate that the PDN GW (105,115) in the V-PLMN (100) and in the H-PLMN (110) are both authorized to be selected for the UE (101) for performing the service.

17. The control node (103,400) of any of claims 12-16, wherein the control node (103,400) is a mobile management entity, MME, or a serving GPRS support node, SGSN.

18. A method in a control node (103,400) of a visited public land mobile network, V-PLMN (100), serving a user equipment, UE, (101), wherein the UE (101) has a subscription with a home public land mobile network, H-PLMN (110), and wherein the method comprises the steps of:

-receiving a request for service from the UE (101);

wherein the method further comprises receiving an indication of V-PLMN permission indicating whether a PDN GW (105) in the V-PLMN (100) is authorized to be selected for the UE (101) for performing the service, and wherein the indication of whether the UE (101) to the UE (101) can expect successful performance of the service is further based on the indication of V-PLMN permission, and wherein the indication to the UE (101) indicates: the UE (101) can expect a successful execution of the service if at least one of the indication of V-PLMN permission or indication of H-PLMN permission indicates that the PDN GW (105) in the V-PLMN (100) or the PDN GW (115) in the H-PLMN (110) is authorized to be selected for the UE (101) to execute the service.

19. A register (117,500) in a home public land mobile network, H-PLMN (110), storing subscription data of a user equipment, UE, (101), wherein the UE (101) has a subscription with the H-PLMN (110), and wherein the register (117,500) is adapted to:

-storing an indication of H-PLMN permission indicating whether a packet data network gateway, PDN GW, (115) in the H-PLMN (110) is authorized to be selected for the UE (101) for performing a service to the UE (101);

-providing an indication of the H-PLMN allowance to a control node (103,400) of a visited PLMN (V-PLMN (100)) serving the UE (101); and

providing an indication of V-PLMN permission to the control node (103,400) in the V-PLMN, wherein the indication of V-PLMN permission indicates whether a PDN GW in the V-PLMN is authorized to be selected for the UE in order to perform the service, wherein the UE (101) can expect successful performance of the service if at least one of the indication of V-PLMN permission or the indication of H-PLMN permission indicates that the PDN GW (105,115) in the V-PLMN (100) or in the H-PLMN (110) is authorized to be selected for the UE (101) in order to perform the service.

20. The register (117,500) of claim 19, wherein the indication of H-PLMN permission is provided in a PDN subscription context.

21. Register (117,500) according to claim 19 or 20, wherein the register (117,500) is a home subscriber server, HSS.

22. A method in a register (117,500) of a home public land mobile network, H-PLMN (110), the register (117,500) storing subscription data of a user equipment, UE, (101), wherein the UE (101) has a subscription with the H-PLMN (110), and wherein the method comprises the steps of:

23. A computer-readable storage medium storing a computer program that, when executed, causes a processor (420,520) to carry out the method according to any one of claims 1 to 11.