[Background of the invention] In mobile communication networks, in order to provide service to a plurality of service regions, it is known to provide an architecture according to which a first part of the network comprises one or more network control entities, each network control entity being arranged to control communications in a given set of service regions associated with that network entity, and a second part comprising one or more access control entities, where each access control entity is arranged to control access to the first part (i. e. to one or more network control entities) from one or more service regions associated with said access control entity. In other words, the first part comprises network control entities, which are designed and arranged to establish, maintain and terminate communications or connections to a mobile unit in one or more service regions associated with said network control entity. Such a first part is sometimes also called a core part, and such a second part an access part.

For example, in the context of mobile networks operating in accordance with the 3rd Generation Partnership Project (3GPP), it is known to provide MSCs (Mobile Switching Center) and SGSNs (Serving GPRS Support Node, GPRS=General Packet Radio Service) as network control entities, and GERANs

(GSM/EDGE Radio Access Network) and UTRANs (UMTS Terrestrial Radio Network) as access networks. In GERAN the access control entity is referred to as a RNS (Radio Network Server) and in UTRAN the access control entity is referred to as a RNC (Radio Networks Controller).

It may be noted that in the context of the present application, the term"service region"will be used generically to specify any type of definable and distinguishable region in which a mobile communication network can provide communication services. For example, the service region can be defined in terms of physical limitations, such as location. An example of this is a cell in a cellular communication network, such as a location area (LA) as known from 3GPP. A service region can also be defined logically, e. g. as a predetermined address region, as for example a routing area (RA) known from 3GPP.

Furthermore, it may be noted that the term"entity"is used generically in the context of the present application, and refers to any functional unit designed and arranged to provide a certain functionality, such as the above-mentioned functions of establishing, maintaining and terminating communications as a network control entity, or the function of providing access to such network control entities as an access control entity. An entity can be provided by hardware (such as a physical unit), software (such as a computer program module) or any suitable combination of hardware and software. A network entity can be located at a given physical location, e. g. in a network node, or can be spread out over several network nodes.

Presently, mobile communication networks are being established, in which one service region may allow different modes of access to a mobile communication network. The different modes of access can e. g. be due to different communication standards, such as circuit-switched or packet-

switched communications. In other words, hybrid networks are known, in which it is possible to have a circuit-switched access (e. g. via standard GSM) or packet-switched access (e. g. via GPRS or UMTS) from a given service region. In such a case, each different mode of access will be associated with its own access network. Consequently, there will be a plurality of access control entities handling communications to one service region. On the other hand, each service region is associated with a given network control entity.

[Object of the invention] The object of the invention is to improve systems having the above described architecture.

[Summary of the invention] This object is achieved by an access control entity described in claim 1, a mobile communication network described in claim 5, a network management entity described in claim 6, and a method described in claim 10. Advantageous embodiments are described in the dependent claims.

According to the present invention, an access control entity is provided that maintains an access record that establishes an association between service region identifiers and network control entity identifiers. Furthermore, the access control entity has a signal routing procedure for routing signals between a service region and a network control entity associated with the service region by looking up the access record, in order to determine the identifier of a service region from the identifier of a network control entity and vice versa. Furthermore, the access control entity has a record changing procedure for changing from a first or old access record to a second or new access record.

The access control entity of the present invention constitutes a significant progress over known access control entities. Namely, in present systems, an access control entity serving a given service region is fixedly associated with the network control entity responsible for said service region. This is very inflexible and makes it difficult to reconfigure a network when passing control over a given service region from one network control entity to another. In contrast thereto, the access control entity of the present invention has high flexibility, as the routing of signals from a service region to a network control entity and vice versa can be changed simply by changing the access record kept for the access control entity.

According to one embodiment of the access control entity of the present invention, after the record changing procedure has been initiated, the signal routing procedure on the basis of the old access record is discontinued, and all signal routing procedure is conducted on the basis of the new record. In other words, all communications having the old association of service region identifiers and network control entity identifiers are discontinued, and all new communications use a new association of service region identifiers and network control entity identifiers.

According to a preferred embodiment, the ongoing communications routed according to the old record are continued until terminated on their own, i. e. terminated by the parties of said communication. On the other hand, all new communications are routed according to the new record. When all communications according to the old access record have been terminated by themselves, then the transition to the new access is complete.

In any case, the concept of the present invention provides great flexibility for a network having a first part comprising network control entities and a second part

comprising access control entities, as the transition of control over a given service region from one network control entity to another network control entity can be handled dynamically at the level of the access control entities, by simply changing an access record.

[Brief description of the figures] Further features and advantages of embodiments of the present invention will become apparent from the following detailed description, which makes reference to the figures, in which Fig. 1 shows a schematic block diagram of a network architecture to which the concept of the present invention can be applied; Fig. 2 shows a flow chart of an embodiment of the present invention; Fig. 3 shows a flow chart of another embodiment of the present invention ; and Fig. 4 shows a flow chart of a further embodiment of the present invention.

[Detailed description of embodiments] Fig. 1 shows a schematic representation of an architecture of a mobile communication network having a first part 1 comprising a plurality of network control entities 11-14, and a second part 2 comprising a plurality of access control entities 21-23. Each access control entity 21-23 handles the access to the first part 1 from respective service regions SR associated with each respective access control entity 21-23.

More specifically, in the example of Fig. 1 access control entity 21 is associated with service regions SR1, SR2, SR3, access control entity 22 is associated with service regions

SR1, SR4 and access control entity 23 is associated with service regions SR2, SR3, SR4 and SR5. It may be noted that the dotted boxes around the respective access control entities and associated service regions symbolize Radio Access Networks (RANs) of the mobile communication network, such as the above mentioned UTRAN or GERAN in 3GPP.

As one can see, one service region, such as service region SR1, can be associated with more than one access control entity, such as entities 21 and 22 in Fig. 1. There can be different reasons for this, e. g. because access control entity 21 operates according to one standard and access control entity 22 according to another. As an example, access control entity 21 could belong to a GERAN and be RNS, whereas access control entity 22 could belong to a UTRAN, i. e. be a RNC. However, this is not necessarily the reason, as it is also possible that more than one access control entity operating according to the same standard is associated with one service region, in order to simplify the traffic handling.

In the architecture of Fig. 1, each service region SR is also associated with one network control entity 11-14, which associated network control entity controls communications in said service region. For example, network control entity 11 could be arranged to control the communications in service region SR1.

Furthermore, each network control entity 11-14 can be arranged to control communications in more than one service region SR, i. e. it can be arranged to control communications in a set of service regions SR, where each set generally has one or more members. If a network control entity is (temporarily) not associated with any service region SR, then the set could also be empty.

The service regions SR can be defined in any suitable or desirable way. For example, they can be defined by a certain physical location, such as location areas LA, or they can be defined logically, such as a region of addresses like a routing area RA. Both location areas LA and routing areas RA are known from 3GPP.

The network control entity 11-14 that controls a given service region SR is chosen and configured in accordance with the SR. For example, if the SR is a location area LA, then the associated network control entity will be a mobile switching center (MSC), whereas if the service area SR is a routing area RA, then the associated network control entity will be a serving GPRS support node (SGSN).

According to the present invention, at least one of the access control entities 21 to 23 keeps an access record that establishes an association between a service region identifier and a network control entity identifier for the service regions associated with the access control entity.

For example, when considering the example shown in Fig. 1, and assuming that service regions SR1 and SR3 are controlled by network control entity 11, while service region SR2 is controlled by network control entity 12, then access control entity 21 may keep an access record that establishes an association or link between an identifier of service region SR1 and an identifier of network control entity 11, between an identifier of service region SR3 and an identifier of network control entity 11, and between an identifier of service region SR2 and an identifier of network control identity 12.

The access record can be provided in any suitable or desirable form, e. g. as a table or as linked list. It must only be able to provide the possibility of mapping an identifier of a service region SR onto an identifier of a network control entity and vice versa.

The identifier kept in the record can also be provided in any suitable or desirable way. For example, the identifiers can be addresses already used by the network for the network control entities and the service regions. As an example, in the context of 3GPP, the network control entities could be identified by signalling connection control point (SCCP) addresses. It may be noted that the identifiers for the network control entities can consist of several parts, depending on the structure of the network and the connections involved. For example, if the part 1 shown in Fig. 1 belongs to one network operator, and the access control entities 21- 23 are arranged to also communicate with network control entities of another network operator (not shown), then an appropriate additional identifier could be introduced, in order to distinguish between the network control entities of the various network operators, like a network ID.

An access control entity operating in accordance with the invention is arranged to execute a signal routing procedure for routing signals between a service region and a network control entity associated with said service region by using the access record. In other words, when routing signals from a service region to the associated network control entity and vice versa, the signal routing procedure maps the corresponding identifiers onto one another.

Additionally, an access control entity operating according to the present invention is also arranged to execute a record changing procedure for changing an access record from an old record to a new record. In other words, if e. g. control over communications in service region SR1 is to be passed from network control entity 11 to network control entity 13, then the record changing procedure for access control entity 21 is conducted, in order to change from the old access record, which provided an association between the identifier of service region SR1 and the identifier of network control

entity 11, to a new access record, which establishes an association between the identifier of service region SR1 and network control 13.

Due to the above described concept of maintaining an access record for an access control entity, said access record being used to map service region identifiers and network control entity identifiers onto each other in order to provide signal routing, and providing a record changing procedure for automatically changing an access record and thereby automatically and easily changing the routing occurring at the access control entity, a highly flexible arrangement is created, which allows simple reconfiguration.

According to a preferred embodiment of the present invention, the process of initiating the record changing procedure in one or more of the access control entities 21 to 23 and corresponding reconfiguration procedures in affected network control entities 11-14 is conducted by a network management entity 31, which is also shown in Fig. 1. The network management entity 31 is preferably part of a central network management unit, with which a network operator can control and configure the network operation. The network management entity 31 can be entirely automated, in that it operates without human intervention, but is preferably also equipped with a man-machine-interface (such as a computer screen for data output and a keyboard for data input), such that a human operator can influence the operation of the network management entity 31.

The network management entity 31 is arranged to execute a reconfiguration procedure for reconfiguring the association between one or more network control entities and one or more service regions, wherein a signal is sent to the one or more access control entities that are affected by the reconfiguration, in order to initiate an appropriate record changing procedure in each of said access control entities.

For example, if control over communications in service region SR1 is to be passed from network control entity 11 to network entity 13, then the network management entity 31 sends an appropriate signal to access control entities 21 and 22, said signal containing an indication that the record changing procedure changes the old record (which associated the identifier of SR1 with network control entity 11) into the new record (which associates the identifier for service region SR1 with the identifier for network control entity 13).

The indication of how to change the old record into the new record can be done in any suitable or desirable way. For example, the network management entity 31 can simply send the complete new access record to the affected access control entity with a command to replace the old access record with the new access record. On the other hand, it is also possible that the network management entity 31 simply sends a message that informs the affected access control entity of a change in identifier association, where the record changing procedure of the access control entity then performs the generation of a new access record, e. g. by simply replacing the identifier of old network control 11 with the identifier of the new network control entity 13 in the appropriate item of the record that belongs to service region 1.

Now an embodiment of a method for reconfiguring the association between one or more network control entities and one or more service regions will be described with respect to the flow chart of Fig. 2. This method can e. g. be initiated and controlled by the network management entity 31.

For the purpose of the description it will be assumed that control over service region SR1 is to be passed from network control entity 11 to network control entity 13. Then, as a first step S1, the establishment of any communications for SR1 under the control of old network control entity 11 is

blocked. In other words, the network management entity 31 sends a signal to the old network control entity 11, such that the network control entity 11 does not allow any communications coming from the network and directed towards a mobile terminal in service region SR1 to be established, and vice versa also refuses to establish any communication for mobile units in SR1 requesting a communication.

Then, in step S2, the new network control entity 13 is appropriately configured to take over control of service region SR1. Regarding the configuring of the new network control entity in step S2, this can be done in any suitable or desirable way, depending on the specific entities involved.

Again, this is preferably done by sending an appropriate message or command from the network management entity 31 to all affected network entities. Such affected network entities will generally be the new network control entity, but could also be one or more further entities. For example, in the context of a 3GPP system, in which the network part 1 furthermore comprises a home location register (HLR), which is not shown, and a visitor location register (VLR), which is also not shown, the transition from old network control entity (e. g. old MSC) to new network control entity (e. g. new MSC) can involve the transfer of all VLR information for user equipment (UE) from the old entity or node to the new entity or node, and the changing of all node pointers in the HLR to point at the new entity or node. Alternatively, no transfer of VLR information is conducted, and the change of node pointers in the HLR to point at the new node is performed directly. However, this implies that the user equipment (mobile units) will be paged in the full coverage area of the affected access control entities (e. g. RNCs).

Then, in step S3, the appropriate record changing procedure is conducted in the concerned access control entities, i. e.

access control entities 21 and 22 in the present example, as both are associated with service region SR1. As a consequence, the access records in access control entities 21 and 22 are changed to thereby reflect the association between SR1 and the new network control entity 13.

Finally, in step S4, the new network control entity 13 receives a signal or command to take up new communications for service region SR1.

The basic method described in connection with Fig. 2 related to the passing of control over new communications from the old network control entity 11 to the new network control entity 13. In the following, with reference to Figs. 3 and 4, different embodiments for treating ongoing communications will be described.

Fig. 3 shows one possibility of specifically implementing the method of Fig. 2. Steps in the method of Fig. 3 that carry the same reference numeral as steps in Fig. 2, are identical, such that a repeated description is not necessary.

In the method of Fig. 3, step S1 is followed by step S5, in which all communications controlled by the old network control entity 11 are forcedly terminated. This means that all ongoing traffic from and to service region SR1 handled by network control entity 11 is terminated by the network control entity 11. Then steps S2, S3 and S4 are conducted, like in the method described in connection with Fig. 2. After step S4, the method of Fig. 3 comprises step S7, in which the data or configuration relating to SR1 is deleted from the old network control entity 11. In other words, this finalizes the transition of control from network control 11 to network control entity 13. In the method of Fig. 3, the transition of control from one network control entity to another entails the interruption of all communications that are ongoing at the time of triggering the transition.

According to a preferred embodiment, which will be explained with reference to Fig. 4, it is possible to make a smoother transition by keeping the communications that are ongoing at the time of triggering the transition, under control of the old network control entity 11, and waiting until all these communications have terminated by themselves (i. e. have been terminated by the parties of the communication), before finalizing the transition and deleting all configuration data relating to the service region SR1 from the old network control entity 11.

Fig. 4 therefore shows another possibility of specifically implementing the method of Fig. 2. Steps in the method of Fig. 4 that carry the same reference numeral as steps in Fig.

2, are identical, such that a repeated description is not necessary.

In the method of Fig. 4, step S1 is followed by a step S8, in which the control of ongoing communications to and from SR1 is continued in the old network control entity 11. Then steps S2 to S4 are conducted, and then thereafter a step S9 is employed, which is performed until all communications ongoing at the initial transition point from entity 11 to 13 have terminated by themselves. Only after all of these ongoing communications have terminated, is step S7 performed, for finalizing the transition from network control entity 11 to network control entity 13.

With respect to the affected access control entities 21 and 22 and the method of Fig. 3, this means that as a part of step S5, the signal routing procedure in the affected access control entities discontinues routing on the basis of the old access record, and all subsequent signal routing is conducted on the basis of the new access record.

With respect to the method of Fig. 4 and the affected access control entities 21 and 22, step S8 means that the signal routing procedures in the affected access control entities continue to be conducted on the basis of the old access record for all communications established before the initiation of the record changing procedure. Only after step S9 indicates that there are no longer any communications that were ongoing at the initial point of the record changing procedure, is the old record finally deleted.

Preferably, the access control entities are arranged such that while the signal routing procedure continues to be conducted on the basis of the old access record for all communications established before the initiating of the record changing procedure, the signal routing procedure is conducted on the basis of the new record for all communications requested after the initiating of the record changing procedure. This is shown in the method of Fig. 4, in which step S4 is conducted prior to step S9. However, it may be noted that step S9 could also be conducted prior to step S4, in which case no new communications under control of the new network control entity 13 are established until all communications under control of the old network control entity 11 have terminated by themselves.

It should generally be noted that the embodiments of Figs. 2 to 4 are only examples, and that the shown steps can also be performed in different order or in parallel. For example, in Fig. 3 step S5 could be executed anywhere prior to step S7.

Equally, it should be noted that Fig. 1 only shows a schematic example, and the present invention can also be applied to systems comprising more or less than the four shown network control entities 11 to 14, more or less than the three shown access control entities 21-23, and more or less than the five shown service regions SR1-SR5.

Although the present invention has been described by way of preferred embodiments, these serve to convey the skilled person a better understanding and are not intended to be limiting. Much rather, the scope of the present invention is defined by the appended claims. Also, reference signs in the claims serve to make the claims more legible, and are not intended to be limiting.