HK1172169A - Handling ics enhanced and non enhanced msc in a pool - Google Patents

Abstract

The invention related to handling core network entities of a radio core communications network comprising a first network entity and a second network entity. The said second network entity differs from the first network entity in that it is capable of processing inter-working between messages exchanged with said radio core communications network and messages exchanged with an IP multimedia subsystem. In other words, one network entity is capable of performing inter-working while the other one not. The first and/or second network entities are provided (S200) with configuration information indicating a relationship between the two network entities. The invention then foreseen routing (S300) messages relating to calls established between the at least one user terminal attached to the entity non capable of inter-working and a further user terminal attached to said IP multimedia subsystem according to said configuration information.

Description

ICS enhanced and non-enhanced MSCs in processing pools

Technical Field

The present invention relates to communications in a network, and more particularly to a method, system, corresponding and related network entities and computer programs for handling network entities of a wireless core communication network. The wireless core communication network includes a network entity capable of interworking (inter-working) between the wireless core communication network and the IP multimedia system and a network entity incapable of performing the interworking.

Background

ICS (IMS centralized services, see TS23.292) in 3GPP aims at studying architecture requirements and alternatives for delivering consistent services to users mainly via services centralized in the IMS domain, irrespective of the attached access type, e.g. CS (circuit switched) domain access or IP-CAN. It also considers how to support services continuously (i.e. service continuity at domain transfer) when the user changes the access type from CS domain to IP-CAN or vice versa, even when engaged in mid-call services.

In order to deploy ICS for existing CS networks, it is necessary to upgrade an MSC (mobile switching center) to have ICS functionality, i.e. to act as a User Agent (UA) for CS users towards the IMS domain, to convert CS signaling into IMS-oriented SIP and vice versa.

The deployment of ICS may vary from network to network, depending on the business plan of the network operator, or depending on the current configuration of the network. Some operators may choose to migrate all CS users to the ICS over a long period of time, and thus they may want to start with small steps to minimize the effort in network integration and development. Some operators may not consider it necessary to upgrade all CS users to ICS in 5 to 10 years, and they may therefore wish to limit the impact on existing CS networks. In both cases, operators want to minimize the impact on the CS network due to ICS.

The current solution foresees that the standard MSC capable of circuit switched connection services should be replaced by an enhanced MSC, thereby enabling the delivery of consistent services. In the present context, the term "enhanced MSC" is used to refer to a network node, such as an MSC, that has the interworking functions described above. In case there is an existing legacy MSC ("legacy" refers to a non-enhanced MSC, or an MSC that is not capable of performing interworking between a wireless communication network and an IP multimedia subsystem) and that is responsible for attaching a user terminal, delivery of a stable service cannot be provided because such a legacy non-enhanced MSC is not suitable for performing registration with the IMS or processing a corresponding message. Thus, the current solution foresees the replacement of all existing MSCs in an area to provide the delivery of consistent services in the same area.

However, as seen above, one problem associated with existing solutions is that the impact of ICS deployment on existing networks already deployed cannot be minimized.

Disclosure of Invention

It is an object of the present invention to overcome at least some of the technical problems of the prior art. It is a further object of the present invention to provide a network entity, system, method and computer program for handling messages between legacy networks and IP network architectures while minimizing the effort required for system integration and maximizing reuse of existing solutions, services, applications and functions.

According to a first aspect of the present invention, there is provided a method for handling a core network entity in a wireless core communication network. The wireless core communication network comprises a first network entity and a second network entity, wherein the second network entity differs from the first network entity in that the second network entity is capable of handling interworking between messages exchanged with the wireless core communication network and messages exchanged with an IP multimedia subsystem. In other words, one network entity is capable of performing interworking, while another network entity is not. The method comprises the step of providing configuration information to at least one of the first and second network entities. The configuration information indicates a relationship between the first core network entity and the second core network entity. The method comprises the following steps: routing messages relating to calls established between at least one user terminal attached to the first network entity and other user terminals attached to the IP multimedia subsystem, in dependence on the configuration information. These steps may be performed sequentially or in parallel, as the case may be.

According to a second aspect of the present invention, there is provided an attachment core network entity for a wireless core communication network. The attached core network entities include a communication entity and a storage entity. The communication entity is adapted to exchange messages related to a call associated with at least one user terminal attached to the attached core network entity over a radio network interface. The storage entity is for storing configuration information indicating a relationship between the attached core network entity and one other core network entity. Furthermore, the attached core network entity differs from the other core network entities in that the other core network entities are adapted to handle interworking between messages exchanged with the wireless core communication network and messages exchanged with the IP multimedia subsystem. In other words, one network entity is capable of performing interworking, while another network entity is not. The communication entity is further adapted to route said message according to said configuration information.

According to a third aspect of the present invention, there is provided a serving core network entity for a wireless core communication network. The service core network entity comprises a processing entity, a forwarding entity and a storage entity. The processing entity is for handling interworking between messages exchanged with said wireless core communication network and messages exchanged with the IP multimedia subsystem. A forwarding entity is for forwarding messages associated with at least one user terminal attached to an attached core network entity, wherein the serving core network entity differs from the attached core network entity in that the serving core network entity comprises the processing entity. In other words, one network entity is capable of performing interworking, while another network entity is not. The storage entity is for storing configuration information indicating a relationship between the serving core network entity and the attached core network entity. The forwarding entity is further adapted to forward the message according to the configuration information.

According to a fourth aspect of the present invention there is provided a system for a wireless core communication network, wherein the system comprises an attachment core network entity as described above and a serving core network entity as described above.

According to a fifth aspect of the present invention there is provided a computer program for handling a core network entity in a wireless core communication network, the computer program comprising instructions configured to: when executed on a programmable system, causes the programmable system to perform a method according to, for example, the above.

Further advantageous embodiments are defined in the dependent claims. Additional examples are provided in the description to facilitate understanding of the invention and to explain other details and advantages related to the invention.

Drawings

FIG. 1 is a flow chart illustrating a method according to an embodiment of the present invention;

fig. 2 is a schematic block diagram illustrating a network entity according to an embodiment of the present invention;

fig. 3 shows a schematic block diagram representing a network entity according to another embodiment of the present invention;

FIG. 4 shows a schematic block diagram of a system according to an embodiment of the invention;

FIG. 5 is a schematic block diagram illustrating a scenario in which the present invention can be applied;

FIG. 6 shows a flow chart representing an attachment procedure according to an embodiment of the invention;

FIG. 7 shows a flow chart illustrating a mobile originated call flow according to an embodiment of the present invention;

FIG. 8 shows a flow chart illustrating a mobile terminated call flow according to an embodiment of the invention;

FIG. 9 illustrates a flow chart showing control of a user equipment UE to detach from an enhanced MSC in accordance with an embodiment of the present invention;

FIG. 10 illustrates a flow diagram showing managing cancellation of local updates according to another embodiment of the invention.

Detailed Description

It should be appreciated that while the following provides exemplary implementations of one or more embodiments of the present disclosure, the disclosed systems and/or methods may be implemented using any number of technologies, whether currently known or in existence. The disclosure should in no way be limited to the illustrative implementations, drawings, and techniques illustrated below, including the exemplary designs and implementations illustrated and described herein, but may be modified within the full scope of the appended claims along with their full scope of equivalents.

In the following, several embodiments and examples of the invention will be presented. It will also be clear from the following description that different embodiments may be combined in different ways according to the principles of the invention.

With reference to fig. 1, a first embodiment of the invention will be described, which relates to a method for handling a core network entity of a wireless core communication network. As explained in more detail below, a network entity is used to refer to one or more network devices or network nodes, which implement predetermined functions in a distributed (by means of a plurality of nodes or devices) or in a centralized (by means of a single node or device). A wireless core communication network (sometimes also referred to simply as CN) refers to the portion of a wireless communication network that includes network entities for performing call and signaling message routing. The core network comprises all those entities of the wireless communication network that do not directly interact with the user terminal over the radio interface. The radio core network typically does not include those devices that directly monitor the network entities communicating with the user terminal. For example, referring to a UMTS network, the core network of a wireless network typically includes MSC devices or MSC servers. In this example, the radio access network typically comprises base stations (or node bs) and radio network controllers (RNC nodes). Network entities or devices of a radio access network (sometimes also referred to as RAN for short) communicate with devices of a core network over a dedicated interface.

In the present invention, the term "circuit switched network" is used to refer to those networks comprising network entities adapted to handle circuit switched operations or circuit switched services. Examples of circuit switched services are voice calls, data calls or short messages like SMS, which are performed according to conventional circuit switched operation at the radio access entity and the core network entity. Typical examples of such networks include GSM, GPRS or UMTS networks. In practice, a radio access network node (e.g. a BSC in a GSM network or an RNC in a UMTS network) or a core network node of the network (e.g. an MSC node) is capable of handling circuit switched operations or circuit switched services. With reference to the UMTS network, reference may be made to those parts of the UMTS network which rely on circuit switched technology or on nodes handling circuit switched operation or circuit switched services between nodes of the radio access network or between nodes of the core network or between the RAN and CN nodes.

Thus, according to one example for putting the first embodiment into practice, the method may be applied to a processing MSC or MSC server of a UMTS radio core communications network. Similarly, the invention is applicable to processing core network devices in networks like GSM, GPRS, etc.

Referring to fig. 1, a wireless core communication network to which the method of fig. 1 can be applied includes a first network entity and a second network entity. The first and second network entities are distinct from each other. More specifically, the second network entity differs from the first network entity in that the second network entity is capable of handling interworking between messages exchanged with the radio core communications network and messages exchanged with the IP multimedia subsystem. In other words, the network entity is capable of processing messages received over the circuit switched access network, including calls and user network signalling, and of interworking with messages of the IP multimedia subsystem, and vice versa. In one example, the messages received over the circuit switched access network may be messages exchanged over the a/Iu or/and E interfaces, and the messages exchanged with the IP multimedia subsystem may be SIP messages. In the present invention, a network entity of the second network entity as described above is referred to as an enhanced network entity for IMS Centralized Services (ICS), or simply as an enhanced network entity. A network entity of the first network entity as described above will be referred to as a non-enhanced network entity for ICS (or simply as a non-enhanced network entity) because the network entity cannot perform the above-described interworking. In one example, the second network entity may be an enhanced MSC network node for ICS or an enhanced MSC server for ICS. According to an example, the first network entity may be a legacy MSC that is only capable of performing circuit switched operations and not the interworking described above. Similarly, the first network entity may be an MSC server that is only capable of handling conventional circuit switched operations and not the interworking described above.

The first network entity is also a network entity capable of attaching a user terminal accessing the wireless communication network through the wireless network interface ("attach" refers to the user equipment performing the necessary operations and steps for establishing a connection to access a service from the network). To perform the attachment, the network devices of the RAN may interact in a manner known in the art. For example, referring to a UMTS network, the first network entity may be an MSC capable of handling circuit switched communications and capable of direct communications, which is an RNC node of a UMTS radio access network. Referring to another example applicable to a GSM network, the first network entity may be an MSC capable of performing circuit switched communications and exchanging information with a BTS controller belonging to a GSM radio access network. As already mentioned above, the above information may be exchanged over interfaces like the a/Iu and/or E interfaces. These messages may be user network messages.

In other words, the method according to the invention is for handling a core network entity comprising at least two network entities, wherein one core network entity is capable of interworking messages between a radio core communication network, such as a conventional circuit switched radio core communication network, and an IP multimedia subsystem. The other core network entity cannot perform the interworking.

The method foresees a step S200 for providing configuration information to at least one of the first and second network entities, wherein the configuration information indicates a relationship between the first and second core network entities. This means that the configuration information may be sent to the first network entity (e.g. an MSC without ICS capability) or the second network entity (e.g. an MSC with ICS capability). In another example, the configuration information may be sent to both the first and second network entities. As will be explained further below, according to a modification of this embodiment, configuration information may be sent to the first network entity (i.e. the network entity not capable of said interworking) to handle the user equipment originating call. According to another example, configuration information may be sent to a second network entity capable of performing the interworking to handle the user equipment terminating call. Thus, if the configuration information is sent only to the first network entity, this may be used to route call related messages from the user equipment to the IMS; in this example, a call originating in the IMS may not be routed to a user equipment accessing the radio access network through a first network entity that is not capable of performing interworking. In an example where the configuration information is provided only to the second network entity, routing of calls originating from the IMS and terminating to user equipment accessing the network through the first network entity (i.e. attaching to or registering in the network through the first network entity) may be performed only while calls originating from the user equipment are routed only according to conventional circuit-switched operations. If the configuration information is provided to both the first and second network entities, UE originating and UE terminating calls may be provided to/from the IMS with consistent service delivery, respectively, by services centralized in the IMS domain. Further examples will be provided in subsequent portions of the description to illustrate how configuration information may be provided to one or both of the first and second network entities.

The method then comprises a step S300 of routing a message relating to a call established between the user terminal described above (i.e. the user terminal attached to the first network entity) and another user terminal attached to the IP multimedia subsystem according to the configuration information, step S300. It is to be noted that herein, user terminal, user equipment or mobile terminal may be used interchangeably, referring to a user equipment capable of connecting to a network. Examples of such devices are mobile phones, laptops, PDAs, etc. The above-mentioned messages may be associated with the above-described user terminal accessing the network through a conventional circuit-switched network entity; however, these messages may also refer to multiple user terminals accessing legacy circuit-switched network devices and multiple user terminals attached to the IMS. In this document, the term "call" is used to refer to any type of connection suitable for carrying user data. Generally, a call refers to the exchange of data between a user terminal and another device. Thus, a call may include a voice call, a video call, a data call, and so on. The call is routed to/from a first network entity (e.g., a non-enhanced MSC or a conventional circuit-switched MSC) and then the call is further routed by the first network entity. The above-mentioned further user terminal attached to the IP multimedia subsystem is a user terminal capable of accessing the communication network and accessing a given set of services in a centralized and consistent way, irrespective of the type of access used, i.e. irrespective of whether access is made via the CS domain or via the IP-CAN. This is made possible by the IP multimedia subsystem to which another user terminal is attachable (i.e. with which another user terminal can register when accessing the network).

The configuration information according to the present method thus allows establishing a relationship and association between the first network entity and the second network entity, i.e. it allows establishing an association between a network entity capable of interworking circuit switched operations and services with IMS operations and services (second core network entity) and a network entity incapable of performing said interworking functions, such as the first core network entity. Based on this information, routing of the call or exchange of messages related to the call may be performed. Thus, even when accessing the network via a conventional telephone-switched network (which is typically not capable of handling IMS operations or services), the user terminal is able to use all the functionality provided by IMS, since the configuration information will direct the first non-enhanced network entity to handle messages via the second enhanced network entity. Thus, by means of the present invention, it is possible to allow a user accessing a network from a conventional circuit switched entity to access an IMS centralized service without replacing or upgrading all core network entities. Thus, enhanced functionality may be achieved with an easy-to-implement solution, with limited impact and reduced modifications to existing deployed networks.

According to an optional modification of the first embodiment, the configuration information may comprise at least first identification information identifying the second network entity. In this case, the information identifying the second network entity may be transmitted only to the first network entity, so that the first network entity will be able to establish a relationship with the enhanced radio core network entity. It should be noted that the configuration information may establish the relationship between the first and second network entities by transmitting explicit information corresponding to the two network entities (or more network entities as will be mentioned below) for which the relationship is to be established. According to another example, the configuration information may indicate to the network entity only identification information of another network entity (or other network entity) that is to establish a relationship or association with the network entity receiving the configuration information. According to an optional modification introduced above, the step of routing the message may be performed at the first core network entity and may comprise: a step of routing a message originating from said one user equipment, i.e. a user terminal accessing the network via a conventional circuit switched core radio network entity, via the second core network entity in dependence of the first identification information. In other words, according to a modification of this embodiment, information corresponding to the second network entity can be communicated to the first network entity, such that the first network entity can route calls originated from a user terminal accessing a conventional circuit-switched network through the second network entity, which user terminal can access services from the IMS in a centralized manner due to the interworking provided by the second core network entity.

It is noted that the configuration information according to the present invention establishes a relationship or association between two core network entities of the wireless core communication network. This means that the present invention enables the mentioned advantages of allowing a user accessing a conventional circuit switched network to access centralized IMS services with a small modification of existing components of the core radio network. In fact, there is no need to incorporate other interworking nodes or gateways between the legacy network and the other network. The gateway based solution actually requires additional adaptations and technical implementation, making the system more difficult to integrate and upgrade and thus more difficult to maintain. By making small changes to existing nodes, the present invention achieves a technical solution that is easier to deploy and more suitable for future migration.

The method according to this embodiment may further and optionally foresee that the first identification information is used for at least identifying other network entities capable of performing the above-mentioned interworking. In other words, depending on the situation, the identification information may establish a relationship or association between the first network entity and two or more network entities, one of which is the second network entity described above. Depending on the situation, the first network entity may refer to one of the two or more other network entities if they are capable of performing the above-described interworking. As described in more detail below, in practice, the first network entity may route calls or process corresponding messages to one of the associated enhanced network entities, depending on, for example, load balancing criteria or depending on the availability of these other network devices. For example, a first network entity may typically refer (refer to) a second network entity; however, in the event of a failure of the second network entity, the first network entity may reference other network entities that represent backups of the second network entity. The configuration information in the first network entity associated with two or more other core network entities may be static or dynamic, which means that the information can be set once for a given period of time (e.g. until a new configuration is specifically established), or dynamically. Dynamic setting means that the information can be changed over time by adapting or updating it according to the situation.

The method according to the first embodiment may optionally foresee that the configuration information comprises second identification information for identifying at least the mentioned first network entity, i.e. the non-enhanced first core network entity.

According to this example, the second identification information may be sent to the second network entity and may include information identifying only the first network entity (or, according to another example, identifying a plurality of non-enhanced core network entities). In this case, the second configuration information implicitly establishes a connection between the second network entity (receiving or storing the second configuration information) and the identification information related to the first non-enhanced core network entity. According to the present example, the step of routing the message may be performed at the second core network entity and may comprise the step of routing a message terminating on at least one user terminal attached to the first network entity in dependence on the second identification information. In other words, according to this example, the second network entity may perform the routing of a call or a corresponding message destined to a user terminal accessing the network through a conventional circuit switched network. This is achieved by using second identification information indicating to the enhanced (core) network entity the non-enhanced core network entity to which the user terminal is currently attached. Thus, a user terminal accessing the network through a conventional circuit switched network can be reached to terminate a call related to a service centralized according to IMS.

The method according to this embodiment may further and optionally foresee that the relationship between the first and second core network entities may comprise indicating that the second core network entity is a serving network entity for the first network entity. In other words, the configuration information may specify that the second network entity is a serving network entity for allowing the first network entity to access and perform interworking operations with the IMS. For example, due to such an association, the first network entity will be able to rely on the second network entity to perform location updates in relation to user terminals attached over conventional circuit-switched networks. The second network entity will be the serving network entity for the operation (e.g. location update) or service.

The method according to this embodiment may further and optionally foresee that the relationship between the first and second core network entities may comprise indicating that the second core network entity is not a serving network entity for the first network entity. In other words, the configuration information may explicitly indicate that the first and second network entities do not have a given relationship, or that a previously provided relationship between the first and second network entities is no longer valid. This situation may occur when a deregistration of the user terminal is performed (e.g. when the user terminal is switched off or is no longer reachable) or when a location update is made in a different area, such that the previously associated second core network entity is no longer in relation or associated with the first network entity. This situation may also occur when the user terminal is not attached to the first network entity but to another non-enhanced core network entity, such that the previous association or relationship needs to be explicitly cancelled by explicitly informing that a given relationship between the two devices does not exist. This indication, that the second network entity is not the serving network entity for the first network entity (e.g. deregistration of the user terminal), may be implemented by adding a new MAP message or modifying an existing MAP message. Detailed examples will be provided below.

The method according to this embodiment may further and optionally foresee that the configuration information is updated when the user terminal is detached from the first core network and attached to another core network entity. The updating step includes: deleting the previous configuration information and/or replacing the configuration information with new configuration information related to the new attached entity. Also, here, it may be implemented by adding a new MAP message or modifying an existing MAP message. Accordingly, the configuration information is updated to reflect the association between the network entities involved in providing the service to the given user terminal. This case is a typical case: wherein the user terminal moves to an area such that either or both of the first and second core network entities change to a new network entity incapable of performing the corresponding function; for example, when an attached network entity cannot attach a user terminal or maintain an association according to the present invention; or when no enhanced network entity is provided corresponding to a given area. For example, when the mobile terminal moves from a first non-enhanced core network entity to other non-enhanced core network entities, the method according to the present invention may foresee updating the configuration information to inform the second network entity of the configuration information indicating that the previously valid relationship between the first non-enhanced core network entity and the second enhanced core network entity is no longer valid. At the same time thereafter, new valid configuration information may be provided that associates other or new non-enhanced core network entities (through which the user terminal accesses the legacy circuit switched access network) with the second enhanced core network entity. According to other examples, when the user terminal moves to a new non-enhanced core network entity served by a different enhanced network entity than the initial second network entity, the configuration information may also indicate a relationship between the new non-enhanced core network entity and the new enhanced core network entity involved in handling a call or message originating from or destined to the user terminal.

When moved from the first non-enhanced core network entity, the user terminal may move to a new (attached) core network entity, which is an enhanced core network entity. Thus, in this case, an association with the second network entity may no longer be necessary. Thus, the configuration information may include an empty field or may indicate that previously valid configuration information should be deleted without providing any replacement thereto. Indeed, the user terminal can now be served directly by the attachment enhanced core network entity, so that the configuration information can be deleted or ignored.

The method according to this embodiment may further and optionally foresee that the second network entity may register the at least one user terminal with the IP multimedia subsystem. The registration may be performed based on configuration information. An example of this operation may also be described with reference to the serving core network entity depicted in fig. 3 or with reference to the flowchart of fig. 6. Thus, even when a user terminal is accessing a legacy circuit switched access network and is attached to a legacy circuit switched (e.g. non-enhanced) MSC, it may still register with the IMS through an enhanced core network entity due to configuration information establishing a relationship between the non-enhanced and enhanced core network entities. Thus, when accessing a network from a conventional circuit switched access network served by a non-enhanced calling network entity (e.g. a non-enhanced MSC), the user terminal is also able to access all IMS services in a centralized manner.

In the following, further embodiments and examples will be provided which illustrate how the invention can be implemented. The same considerations made above with reference to the first embodiment also apply below, so that the above observations apply as well. Accordingly, references to the above sections are equally applicable to the disclosure below, which will focus only on the principal aspects necessary to clarify each embodiment or example provided.

A second embodiment of providing an attached core network entity 100 will be described with reference to fig. 2. Fig. 2 is a schematic block diagram comprising an attached core network entity 100, the attached core network entity 100 comprising a communication entity 110 and a storage entity 120. The attached core network entity is an entity comprised in the wireless core communication network, as described above. In one example, the attached core network entity 100 may be the first network entity mentioned in the method of the first embodiment. Fig. 2 also shows a user terminal 300, which user terminal 300 is capable of accessing IMS services, but still accesses the communication network via a conventional circuit switched radio access network (e.g. via a node that is not capable of performing the required interworking).

The communication entity 110 is an entity adapted to exchange messages over a radio network interface relating to a call associated with at least one user terminal attached to the attached core network entity 100. The user terminal may be attached to the network entity 100 by the communication entity 110 or by a dedicated attachment entity not shown in the figure. The wireless network interface through which the user terminal establishes communication with the wireless communication network may comprise a communication interface adapted to perform communication between the user terminal and one base station or interface allowing communication between two nodes of the wireless communication network. According to an example, the radio network interface may be an Iu interface in a UMTS radio access network, or an a interface in a GSM network. In other words, the communication entity 110 is an entity that provides a conventional interface to a circuit switched wireless network and thus does not have ICS capability (i.e. cannot provide any centralized IMS services).

The storage entity 120 is an entity adapted to store configuration information indicating a relationship with attached core network entities not shown in fig. 2. The same considerations apply for the configuration information as above with reference to the method of the first embodiment. Thus, the storage entity 120 stores the relationship between the non-enhanced (i.e. without ICS capability) network entity 100 and the other core network entity (enhanced core network entity). The other core network entity mentioned above may be the second network entity discussed in the above method, or further described in detail in the corresponding example below. It is noted that the attached core network entity 100 of the present embodiment differs from the other core network entities mentioned in that the other core network entities are adapted to handle interworking between messages exchanged with the wireless core communication network and messages exchanged with the IP multimedia subsystem. In other words, the storage entity 120 stores information expressing the relationship between one attachment entity without ICS capability and another network entity with ICS capability. As can be seen below, the MSC3 is an example of an attached core network entity 100 according to the present embodiment, while the MSCA is an example of other core network entities with ICS capability, as shown in fig. 5 and described in the corresponding paragraphs below.

The communication entity 110 is further adapted to route the above mentioned messages according to the configuration information. In other words, the communication entity attached to the core network entity 100 routes messages related to calls to/from other network entities, thereby allowing a user terminal attached to a non-enhanced core network entity (i.e. through a legacy circuit switched RAN and a legacy circuit switched core network entity) such that the user terminal can access all services provided over IMS in a centralized manner.

Thus, thanks to the present invention, and more particularly to the configuration information, the user terminal is able to access IMS centralized services in a consistent way even through non-enhanced core network entities without requiring substantial modifications or adaptations to the existing core network. Configuring a conventional non-enhanced core network entity to process configuration information is actually easier to implement and maintain than re-developing the same entity or device to provide interworking functionality. Accordingly, a user terminal accessing a network through a legacy device can access an IMS center service while minimizing maintenance work for network development or integration.

The configuration information mentioned above with reference to the attached core network entity 100 may optionally comprise at least first identification information identifying the other network entities mentioned above, wherein it is recalled that the other network entities may be ICS-capable network entities. In this case, the communication entity 100 may be further adapted to: messages originating from the mentioned at least one user terminal (attached to the non-enhanced core radio network entity) are routed to other core network entities based on the first identification information. In other words, according to the present example, the configuration information may simply identify other enhanced core network entities, such that the relationship-the relationship between the attached core network entity 100 and the other core network entities is implicitly inferred by the attached core network entity 100. Thus, messages related to the call are processed according to the described associations or relationships.

The above-mentioned first identification information may further and optionally comprise information for identifying at least another network entity capable of performing the above-mentioned interworking. In other words, according to the present example, the first identification information may establish a relationship between the attached core network entity 100 and two or more wireless core network entities capable of performing interworking (i.e., two or more enhanced wireless core network entities). Thus, the mentioned messages may be routed to one or the other enhanced core network entity depending on e.g. load balancing, failure occurrence of one of the two entities or other considerations according to the situation. Other examples are provided below to illustrate other advantages of the present invention.

A third embodiment of the serving core network entity is now described with reference to fig. 3. Fig. 3 shows a serving core network entity 200 according to a third embodiment. It can be seen that the entity 200 is capable of establishing communication with the IP multimedia subsystem 400 and the core network entity 100. The core network entity 100 may be the attached core network entity 100 described in the second embodiment and shown in fig. 2. The entity 100 shown in fig. 3 may also be represented by the first network entity described with reference to the method of the first embodiment. The serving core network entity 200 is a network entity for a wireless core communication network and comprises a processing entity 210, a forwarding entity 220 and a storing entity 230.

The processing entity 210 is an entity for handling inter-working between messages exchanged with the wireless core communication network (e.g. with the device 100 and/or with other devices not shown in fig. 3) and messages exchanged with the IP multimedia subsystem 400. Due to the functionality of the processing entity 210, the serving core network entity 200 is an enhanced radio core network entity as described above or in the following.

The forwarding entity 220 is an entity adapted to forward messages associated with at least one user terminal attached to an attached core network entity, of which the network entity 100 represents an example. The serving core network entity 200 and the attached core network entity are distinguished from each other in that they comprise processing entities. In other words, the serving core network entity and the attached core network entity differ in that the former is an enhanced core network entity and the latter is a non-enhanced core network entity. The storage entity 230 stores configuration information such as associations between enhanced and non-enhanced core network entities.

In this way, the forwarding entity 220 is adapted to forward the mentioned message according to the configuration information. Thus, the serving core network entity 200 can ensure that: based on the configuration information, the consistent service is also delivered to the user attached to the non-enhanced core network entity via a service centralized in the IMS domain. The invention thus enables the delivery of a consistent service to be extended to several user terminals via the IMS domain without the need to upgrade and modify all core radio network entities in a given network. Instead, the present invention only requires upgrading a limited number of entities to an enhanced network entity capable of providing the required service based on the configuration information. Therefore, the scheme provided by the invention has less influence on the existing network through a simple implementation scheme.

According to an example, the messages forwarded by the forwarding entity 220 may comprise messages related to a call associated with at least one of the user terminals mentioned above. In other words, the message represents a call routed according to the configuration information. Thus, according to the present example, the serving core network entity 200 is able to forward call related messages based on configuration information representing an association between enhanced and non-enhanced wireless core network entities.

According to another example, the messages forwarded by the forwarding entity 220 comprise at least a registration message for registering at least one user terminal with the IP multimedia subsystem based on the configuration information. An example of implementing this modification of the third embodiment will be provided below with reference to, for example, fig. 6. In other words, when the message forwarded by the forwarding entity 220 comprises a registration message, and when the user terminal is attached to a non-enhanced core network entity, the serving core network entity is able to perform registration of the user terminal with the IMS over a legacy circuit switched network access network. That is, due to the specific settings based on the configuration information, the user terminal is able to register with the IMS to use the corresponding service without the need to attach to an enhanced core network entity as required in the prior art. Thus, in order to allow a user terminal to access IMS services, it is not necessary to modify all core network entities in order to perform interworking. In contrast, according to the invention, only few adaptations or upgrades in the network are required.

The configuration information may optionally comprise identification information for identifying at least one attached network entity, wherein the attached network entity may be the entity 100 described with reference to the second embodiment or the first network entity described with reference to the first embodiment. In this case, the forwarding entity is further and optionally adapted to route messages terminating on at least one user terminal, i.e. a user terminal accessing the communication network from a conventional circuit switched RAN and attached to a conventional circuit switched core network entity, in accordance with the above mentioned identification information. This means that the message is forwarded to the ICS-incapable core network entity specified by the identification information included in the configuration information.

Thus, due to the configuration information, the serving core network entity according to the third embodiment is able to register the user terminal with the IMS network or handle calls related to the corresponding service for user terminals attached to the non-enhanced core network entity. This results in the following advantages: the user terminal is able to access IMS centralized services without deploying interworking functions on all core network entities, only a limited number of them. This results in an easy to implement solution.

A fourth embodiment of a system for a wireless core communication network will be described with reference to fig. 4. The system comprises at least one attached core network entity and at least one serving core network entity. The attachment network entity 100 in the second embodiment may be an example of the serving core network entity 4200 in fig. 4. Furthermore, the first and second network entities described with reference to the first embodiment may represent examples of the attachment core network entity 4100 and the serving core network entity 4200, respectively, described in fig. 4. Therefore, similar considerations as above apply to the network entities in the system of fig. 4. Due to the configuration information, the attached core network entity 4100 is able to exchange messages with the serving core network entity 4200, such that a user terminal attached to a non-enhanced core network entity is able to register with and exchange messages with the IMS through the enhanced core network entity 4200, the network entity 4100 being associated with the enhanced core network entity 4200 by means of the configuration information. The same applies to the serving core network entity 4200, which is able to perform the actual registration or routing of calls terminated at the mentioned user terminal by referring to the serving core network entity based on the configuration information.

The system in fig. 4 optionally comprises a database 4500 for storing configuration information and for forwarding the configuration to at least one of the attachment core network entity and the serving core network entity. Database 4500 may be included in other network entities that are capable of determining configuration information to be stored in the database. The determination of configuration information may be made in a static manner (e.g., performed once for all or a given period of time until new configuration or maintenance occurs) or in a dynamic manner so as to change and adapt depending on the situation or network conditions. As mentioned below, the HLR is an example of an implementation of the database 4500 according to the present invention.

According to another embodiment, the invention also foresees a computer program for handling core network entities in a wireless core communication network, wherein the computer program comprises instructions configured to cause a programmable system to perform the steps of the method according to the first embodiment described above, when executed on the programmable system. Indeed, the reader will appreciate that the present invention can be implemented by a computer program specially adapted to perform the method according to the present invention. A computer system for executing a computer program comprises typical entities such as processing entities or units, memory (volatile or non-volatile, such as RAM, ROM, hard disk, etc.) and necessary input and/or output devices, which are required for executing instructions.

The skilled person will also appreciate that the invention can in fact be implemented more suitably by hardware, software or any combination thereof, depending on the situation. Further, the invention or portions of the invention may be implemented in a distributed or centralized manner, as appropriate.

In the following, examples will be provided which show how the invention or different embodiments thereof can be applied in practice. Further, examples will be provided that show how the different processes can be performed according to the principles of the present invention.

Fig. 5 illustrates a scenario representing one way of causing minimal impact on a circuit-switched network when it is desired to provide IMS centralized services over a conventional circuit-switched network. The MSC in fig. 5 is an example of a network entity of a radio core network according to the present invention. The configuration shown in fig. 5 foresees: keeping the existing MSC nodes almost unchanged, only upgrading or adding some ICS enhanced MSC nodes in the network to handle all the traffic in the network related to ICS.

As mentioned in the opening part of the description, the current solutions do not meet the requirements for operating the network solution. For this reason, current prior art solutions foresee that upgrading and replacing all legacy MSCs with upgraded or enhanced MSCs means a large impact on the deployment of the network. As shown in fig. 5, assuming that MSCA and MSCB have ICS capability, the discovery of the present invention is based on having MSCA and MSCB act like an ICS proxy for all other MSCs (non-enhanced MSCs), so that traffic to/from other MSCs will go through MSC a/B acting as the ICS user agent for the subscriber. However, according to the currently known scheme, when the user equipment is switched on, a location update will be made so that the HLR will obtain the location of the user equipment pointing to the MSC 3. When the user equipment moves to MSC5, the HLR will have its new location pointing to MSC 5. Thus, since nodes MSC3 and MSC5 do not have ICS capability, the user will not be able to register with the IMS network and will not be able to use the service in a centralized manner over the IMS. In contrast, according to the invention, the node MSC a/B operates like an IMS-oriented ICS gateway for the other MSCs. As mentioned above, the present invention achieves this by introducing the use of configuration information that will facilitate the cooperation of enhanced and non-enhanced MSCs.

It is to be noted that MSCA and MSCB are examples of the serving network entity described in the third embodiment or the second network entity described in the first embodiment. Similarly, the node MSC3 or MSC5 is an example of an attaching core network entity according to the first or second embodiment.

Still referring to fig. 5, the implementation of the configuration information may enable MSC a and/or B to function as: for a user equipment of an ICS, indicating to the HLR that the HLR should point to MSC A or/and B until the user equipment moves out of the control of MSC A/B.

In one example, the scheme may optionally be applied only to home network scenarios. If the subscriber is roaming towards a visited network, the VMSC will receive a roaming profile, which may be different from the home profile, according to the present example. The roaming profile may instruct the VMSC to use normal origination procedures and not route the originating call to the home IMS.

Returning to fig. 5, MSCA and MSCB have ICS capability, and MSCs 3-7 do not have ICS capability. By configuration, the MSCA and MSCB are able to know which MSCs will be served for the ICS. In this case, MSC3 to MSC 7. Also, by configuration, MSC 3-MSC 7 will route all outgoing calls to MSCA or MSCB. In the HLR, MSCA and MSCB are "associated" with MSC3 to MSC7 for ICS by configuration.

When the UE attaches to the CS network (MSC3, see step 1 in fig. 5), the HLR will obtain its location (after location update of step 2) and know that MSCA and MSCB are associated with MSC3 (step 3). The HLR then sends the information to MSCA or MSCB telling the UE to turn on (step 5). For each served MSC (i.e., MSC 3-MSC 7), there is an associated primary serving MSC (e.g., MSCA) and an associated secondary serving MSC (e.g., MSCB). Under normal circumstances, the HLR will send this information to the primary serving MSC. If the primary serving MSC fails, the information will be sent to the secondary MSC. This may be for redundancy reasons (note that two MSCs a/B are optional, as the functionality of the invention may also be applied to only one enhanced MSC). The information sent by the HLR may be a new message sent from the HLR to MSCA/B or some new information element (e.g. ICS flag) in an existing message (this may be an insert subscriber data message ISD, indicating the IMSI of the UE and the MSC3 node address, according to an example). The message needs to include the IMSI so that the selected serving MSC can derive the required IMS subscriber identity (see 3GPP 23.292). Thus, the MSCA/B will know that the UE is up and its serving MSC is MSC 3. The MSCA/B will then send an IMS registration to the IMS domain on behalf of the UE.

With continued reference to FIG. 6, the steps shown therein will be described in greater detail. The attach procedure foresees a step 2 of performing a location update, wherein the MSC3 to which the user equipment is now attached informs the HLR of the current location of the user equipment, e.g. the MSC3 is the core network node to which the user equipment is currently attached. At step 3, the HLR will look up the node associated with MSC 3. In the present case, this node is represented by one or both of the nodes MSC A/B, as shown in FIG. 5. Once the associated MSC a/B is found, the HLR will provide the MSC3 with further information, as described in step 4. This other information includes (optionally) subscriber data and new information elements, including for example the MSC a/B address (or the address of just one of the MSCs a/B). The information provided in step 4 of fig. 6 is an example of the configuration information described above, as they provide the MSC3 with the MSC a/B address (an example of identification information representing a network entity), while the MSC3 is now able to establish a relationship between itself and the enhanced core network node. Subsequently, referring to step 5 of fig. 6, the HLR informs the MSC a/B (one or both of the nodes MSC a and MSC B shown in fig. 5) that the user equipment is started and that the corresponding serving node is the node MSC 3. The HLR optionally also transmits further subscriber data of the user equipment to inform the MSC a/B in step 5.

Thereafter, the MSC a/B (one of the two nodes according to the example) can register the user equipment in the IMS based on the information received in step 5.

Thus, the user equipment can register with the IMS even if attached to a non-enhanced core network node.

Reference is now made to fig. 7. Fig. 7 shows the message flow that occurs, for example, in communication with a mobile originated call following the attachment procedure described above. In step 1, the user equipment makes a call, denoted as a mobile originating MO call. In step 2, the decision to route the call to MSCA or B is based on the configuration, i.e. the primary route from MSC3 will be directed to the primary serving MSC of MSC3 and the secondary route to the secondary serving MSC of MSC3, both configured in the HLR. According to an example, the secondary route is only used when the primary serving MSC fails (again, the invention is applicable to the case where only MSCA or MSCB is present). The configuration and usage rules (corresponding to the configuration information described above) in MSC3 have been received from the HLR, which ensures that the call will be routed to the correct serving MSC, which actually performs the registration of the UE in the IMS.

The primary and secondary serving MSCs may be different for different MSCs (from MSC3 to 7), enabling load balancing between MSCA and MSCB. This load balancing should be statically configured or alternatively easily achieved by using for example a round robin algorithm in the HLR (selecting the ICS capable primary and secondary MSC when receiving a location update from a non-ICS capable MSC). The use of two enhanced MSCs provides other advantages, such as enhanced availability. In step 3, the caller is checked and the call is routed to the caller to complete the operation.

Referring now to fig. 8, fig. 8 illustrates call flow in the case of a mobile terminated call. In step 1, a mobile terminated call arrives from the IMS to one or both of the enhanced nodes MSC a/B. In step 2 it is found which is the serving node (MSC3 in this example) and the call is sent to this node accordingly. The process of finding the serving MSC3 is for example performed based on configuration information providing an association between the enhanced node MSC a or/and MSC B and the non-enhanced node MSC3 to which the user equipment is currently attached. Note that the configuration information optionally also comprises information identifying the user equipment such that the core network entity can associate the current information with the correct user equipment.

If the user equipment moves to a different MSC, such as MSC 8 shown in fig. 8, which MSC 8 is not served by an MSC a/B enhanced for ICS, the HLR informs MSC a/B (one or both of nodes MSC a and MSC B, depending on the embodiment) of this. According to an example, a delete subscriber data MAP operation (VSD) is sent indicating the IMSI of the user equipment and a flag for MSC revocation that is known to be ISC capable. Thus, the MSC A/B deregisters the user equipment in the IMS. This situation is illustrated in fig. 9, i.e. the message flow in case the user equipment moves out of control of the enhanced node, e.g. node MSC a or MSC B. More specifically, in step 1 of fig. 9, the user equipment is attached to the non-enhanced node MSC 8. This operation may be performed after the user equipment is switched on or after the user equipment has moved from the previous node to which it was attached to another area served by MSC a. Upon attaching the user equipment, the MSC 8 performs a location update with the HLR as shown in step 2. After the location update, the HLR (see step 3 of fig. 9) finds that MSC 8 is not associated with MSC a or MSC B. In other words, the HLR discovers that MSC 8 is not associated with an enhanced network entity capable of performing interworking with IMS. Thus, the HLR performs a cancel location with MSC3, as shown in step 4; this means that the non-enhanced MSC3 is informed to cancel the location related to the user equipment UE. In step 5, the HLR sends a message to one or both of nodes MSC a and MSC B informing it to delete subscriber data associated with user equipment moving to the area served by MSC 8, as shown in step 5 of fig. 9. In the same step 5, the MSC a/B is informed that the user equipment UE is out of its control. In step 6, the MSC A/B deregisters the user equipment UE in the IMS. Steps 4 and 5 of fig. 9 are examples of the steps described in the first embodiment, wherein the network entities are informed that they are no longer associated.

Note that the terminating call will be routed from the IMS to MSC a or B, which routes it to the serving MSC. However, this is not optimal. Alternatively, the SCC AS is configured to: terminating calls to the CS domain are always interrupted when the call is not terminated over PS (packet switched) access. In case a network scenario (TS23.292) is also deployed with an MSC server enhanced for ICS, MSC 1 or 2 can indicate in the registration that the contact does not apply for termination. This indication is used by the SCC AS to determine that the contact was selected by the T-ADS and then CS breaking operations should be used instead of the regular IMS termination towards the contact.

When the operator cancels the location for the subscriber, the HLR detects that the subscriber has an ICS flag and is registered in MSC3 and ICS capable MSCA/B, so the HLR sends the cancel location to MSC3 and a new message to MSCA/B to deregister from IMS (in one example, a DSD MAP operation is sent indicating the IMSI of the UE and the flag of the revocation without ICS capability).

FIG. 10 illustrates a message flow involved in managing the process of canceling a local update. In step 1, the HLR determines that a management cancel location procedure must be performed. Thus, in step 2, the HLR looks up the MSC associated with MSC A/B. In step 3, the HLR sends a cancel location request to MSC3 found in step 2. Thereafter or simultaneously, the HLR sends a message in step 4 indicating the deletion of subscriber data and informing the user equipment that the UE is not under the control of the given MSC a/B. In step 5, the MSC A/B deregisters the user equipment UE in the IMS.

According to one example, an existing MAP interface may be enhanced according to an example in which the present invention is applied in practice. For example, insert subscriber data ISD and delete subscriber data DSDMAP operations may be introduced to carry ICS information. To convey this information, the ISD MAP operation may be modified as follows according to an example of the application of the invention to practice:

inserting subscriber data MAPV3

Operation code 7

Class 1

ASN.1 formal description

-including naea-PreferredCI depending on the discretion of the HLR operator

If the network access mode parameter is sent, it should only be present in the first sequence if segmentation is used.

Wherein

icsCapableVLR-List::＝SEQUENCE SILE(1..maxNumOflCSVLRs)OF

ISDN-AddressString

maxNumOfICSVLRs INTEGER::＝n

Note that in the above and in the following examples, expressions like "XX", "XZ" represent placeholders for actual or real information element numbers, determined case by case or e.g. according to applicable criteria.

In the above example, note that the value of maxNumOfICSVLRs needs to be declared. Due to redundancy, it may be 2, but the maximum value is not specified.

Note also that in the present invention only ISD MAPV3 is shown, but ISD MAPV1 and MAPV2 should be similarly upgraded.

To communicate ICS information, the DSD MAP operation may be implemented in the following example manner (indicated in bold characters):

deleting subscriber data (HLR- - > VLR/SGSN)

Operation code 8

Class 1

ASN.1 formal description

In accordance with previous considerations, the insert subscriber data MAP operation may now optionally:

transfer information of the associated ICS-capable MSC to the non-ICS-capable MSC where the subscriber is currently located.

Transfer information of the associated ICS-non-capable MSC to the ICS-capable MSC where the subscriber is currently located.

In light of the previous considerations, the delete subscriber data MAP operation must now optionally:

transfer information of the associated ICS-non-capable MSC to the ICS-capable MSC where the subscriber is currently located.

The behavior described above can be summarized in the following table for each use case:

the above table shows the attributes carried in the MAP operations involved for each use case according to an example illustrating the functionality of the present invention.

According to one example, the configuration of the relationship between an ICS-capable MSC and an ICS-incapable MSC can be centralized only in the HLR, so the MSC is unaware of the relationship until traffic occurs. For example, the following table may be implemented in the HLR:

the table above shows an example of a total of m MSCs. Some MSCs are ICS-enhanced (their number may be larger than n, but cannot be larger than m), and of these MSCs, n MSCs (shown in the table above as MSC-ICS) are designated as serving MSCs for MSCs without ICS capability. As an example, the secondary ICS-capable MSCs are allocated in reverse order. When redundancy is desired, n may be equal to or greater than 2. Although only MSCA and MSCB are included in the present invention, the number of MSCs with ICS capability is not limited to 2. The invention is also applicable in the case of networks having more than two ICS-capable MSCs.

The above table provides examples of implementation configuration information. In this example, the configuration information specifies an association between the non-enhanced MSC and the two or more enhanced MSCs. However, as already explained before, the configuration information may also include an association between only the non-enhanced MSC and the enhanced MSC. Alternatively, the configuration information may simply indicate to one non-enhanced node the address of the associated enhanced node and vice versa. Furthermore, the table is only one way to represent configuration information: in fact, the configuration information may be implemented by other types of data structures (e.g., lists), as appropriate.

Furthermore, the table may be implemented in an analysis tree algorithm. The table above is created statically by configuration. Alternatively, the table may be dynamically created by obtaining a list of non-ICS capable MSCs and a list of ICS capable MSCs, and by creating an association between the two MSCs using, for example, a round robin algorithm when the LU of the UE is received. This method will result in a well balanced distribution.

There is a category for ICS-capable subscribers, e.g. as specified in the appropriate standard as TS 23.292.

Processing according to another example of the invention may be described as follows:

1 when a subscriber updates the location in the HLR, the HLR gets the subscriber information and checks the ICS-capable class.

2 if the subscriber has ICS capability, the MSC number received in the LU message, e.g. MSC3, is analyzed.

3 if the MSC3 is in the table (i.e., found in the configuration information), then MSCA/B is assigned to it.

The 4HLR gets MSCA/B and MSC3 and stores the location information internally.

5 sends the insert subscriber data to MSC3 with a new specific parameter indicating the MSCA/B address.

6 sends another new message to MSCA/B indicating IMSI, MSC3 address, status information (registration or deregistration) and possibly more information.

From this point on, 7 knows the MSC3 for that subscriber MSCA/B.

MSCA/B is known to 8 for this subscriber MSC 3.

The same is true for the HLR, which knows and maintains all relationships.

The invention achieves several advantages, such as:

allowing ICS deployment with minimal impact on existing CS networks.

If an operator chooses to migrate its CS subscribers to ICS over a long period of time, a cost-effective and easy-to-implement ICS solution is provided.

Provide HLR based routing methods, not applicable CAMEL.

The interaction between enhanced and non-enhanced MSCs is improved.

With regard to the advantages over CAMEL-based schemes, the following is actually noted. Some alternative techniques are known in the art, which are commonly referred to as CS to IMS overlay. They use CAMEL/intelligent network services to implement an IMS-oriented interface. IN this technique, there is no need to enhance the MSC, since the conversion is performed by an IN application on the SCP. The IN interface is invoked by the OICK or OCSI service indicator subscribed IN the HLR. In contrast, according to the present invention, an easier and more flexible embodiment can be realized.

In the above description, reference has been made to a network entity or a component entity (e.g. a communication entity or a storage entity). Recall that these entities can be implemented in one network node or network device or in a network node of multiple devices (distributing the required functionality in a suitable way).

Furthermore, the reader will appreciate that several embodiments and features thereof may be interchanged as desired. The examples may also be combined as desired, the reader will appreciate that any combination thereof (or partial combination thereof) is possible without substantial modification to what has been described.

The present invention has been described with reference to particular embodiments and examples, which are illustrative and not restrictive. Those skilled in the art will appreciate that many different combinations of hardware, software, and firmware may be suitable for practicing the present invention. In addition, other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only. To this end, it is to be understood that aspects of the invention are not necessarily drawn to all features of an individual embodiment or configuration disclosed herein. Accordingly, the true scope and spirit of the invention is defined by the appended claims.

Terms used herein, such as communication entity, storage entity, or forwarding entity, do not limit how these elements are distributed and aggregated. That is, the elements, components or physical components may be distributed in different software, hardware components or devices in order to introduce desired functions. A number of different elements may also be aggregated to provide the desired functionality.

Any of the above entities (network entities, elements, network devices or network nodes) may be implemented by hardware, software, Field Programmable Gate Arrays (FPGAs), Application Specific Integrated Circuits (ASICs), firmware or the like.

In other embodiments of the invention any of the above and/or claimed parts, such as the controller or the receiver, may be replaced by corresponding control means or receiving means, which list is not exhaustive.

Claims (18)

1. A method for handling core network entities in a wireless core communication network, the wireless core communication network comprising a first network entity and a second network entity, wherein the second network entity differs from the first network entity in that the second network entity is capable of handling interworking between messages exchanged with the wireless core communication network and messages exchanged with an IP multimedia subsystem, the method comprising the steps of:

providing (S200) configuration information to at least one of the first and second network entities, the configuration information indicating a relationship between the first core network entity and the second core network entity; and

routing (S300) messages relating to calls established between at least one user terminal attached to the first network entity and other user terminals attached to the IP multimedia subsystem, according to the configuration information.

2. The method of claim 1, wherein the configuration information comprises first identification information identifying at least the second network entity, and

the step of routing the message is performed at a first core network entity and comprises: routing a message originating from the at least one user terminal to the second core network entity based on the first identification information.

3. A method according to any preceding claim, wherein the first identity information is used to identify at least other network entities capable of performing the interworking.

4. The method according to any of the preceding claims, wherein the configuration information comprises second identification information identifying at least the first network entity, and

the step of routing the message is performed at the second core network entity and comprises: routing messages terminating on the at least one user terminal attached to the first network entity according to the second identification information.

5. The method according to any of the preceding claims, wherein

The relationship between the first core network entity and the second core network entity comprises: indicating that the second network entity is a serving network entity for the first network entity.

6. The method according to any of the preceding claims, wherein

The relationship between the first core network entity and the second core network entity comprises: indicating that the second network entity is not a serving network entity for the first network entity.

7. The method according to any of the preceding claims, wherein

Updating the configuration information when the user terminal is detached from the first core network entity and attached to another core network entity.

8. The method according to any of the preceding claims, wherein

The second network entity registers the at least one user terminal with the IP multimedia subsystem.

9. An attachment core network entity (100) for a wireless core communication network, the attachment core network entity comprising:

a communication entity (110) adapted to exchange messages relating to a call associated with at least one user terminal attached to the attached core network entity over a radio network interface;

a storage entity (120) for storing configuration information indicating a relationship between the attached core network entity and one other core network entity, wherein the attached core network entity differs from the other core network entity in that the other core network entity is adapted to handle interworking between messages exchanged with the wireless core communication network and messages exchanged with the IP multimedia subsystem; and wherein

The communication entity (110) is further adapted to route the message according to the configuration information.

10. The attached core network entity of claim 9, wherein

The configuration information comprises first identification information identifying at least the other network entity, an

The communication entity is further adapted to: routing messages originating from the at least one user terminal to the other core network entity based on the first identification information.

11. An attached core network entity according to claim 9 or 10, wherein

The first identification information is used to identify at least another network entity capable of performing the interworking.

12. A serving core network entity (200) for a wireless core communication network, the serving core network entity comprising:

a processing entity (210) for handling interworking between messages exchanged with the wireless core communication network and messages exchanged with an IP multimedia subsystem;

a forwarding entity (220) for forwarding messages associated with at least one user terminal attached to an attached core network entity, wherein the serving core network entity differs from the attached core network entity in that the serving core network entity comprises the processing entity;

a storage entity (230) for storing configuration information indicating a relationship between the serving core network entity and the attached core network entity;

wherein the forwarding entity (220) is further adapted to: and forwarding the message according to the configuration information.

13. The serving core network entity (200) of claim 12, wherein

The message comprises a message relating to a call associated with the at least one user terminal.

14. The serving core network entity (200) according to claim 13 or 14, wherein

The messages comprise at least a registration message registering the at least one user terminal with the IP multimedia subsystem based on the configuration information.

15. The serving core network entity according to any of claims 12 to 14, wherein the configuration information comprises identification information identifying the at least one attachment network entity, and the forwarding entity is adapted to: and routing the message terminated on the at least one user terminal according to the second identification information.

16. A system (4000) for a wireless core communication network, the system comprising an attachment core network entity (100, 4100) according to any of claims 8-10 and a serving core network entity (200, 4200) according to claim 11 or 12.

17. The system of claim 16, further comprising: a database (4500) storing the configuration information and forwarding the configuration to at least one of the attachment core network entity and the serving core network entity.

18. A computer program for handling a core network entity in a wireless core communication network, the computer program comprising instructions configured to: when executed on a programmable system, cause the programmable system to perform the steps of the method according to any one of claims 1 to 8.