WO2015007310A1 - Re-registration in case of hss outage - Google Patents

Re-registration in case of hss outage Download PDF

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Publication number
WO2015007310A1
WO2015007310A1 PCT/EP2013/064994 EP2013064994W WO2015007310A1 WO 2015007310 A1 WO2015007310 A1 WO 2015007310A1 EP 2013064994 W EP2013064994 W EP 2013064994W WO 2015007310 A1 WO2015007310 A1 WO 2015007310A1
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WO
WIPO (PCT)
Prior art keywords
registration request
user
received
call session
control function
Prior art date
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PCT/EP2013/064994
Other languages
French (fr)
Inventor
Jiadong Shen
Gerhard Kieselmann
Alexander Milinski
Peter Kim
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Nokia Solutions And Networks Oy
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Publication date
Application filed by Nokia Solutions And Networks Oy filed Critical Nokia Solutions And Networks Oy
Priority to PCT/EP2013/064994 priority Critical patent/WO2015007310A1/en
Publication of WO2015007310A1 publication Critical patent/WO2015007310A1/en

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W60/00—Affiliation to network, e.g. registration; Terminating affiliation with the network, e.g. de-registration
    • H04W60/02—Affiliation to network, e.g. registration; Terminating affiliation with the network, e.g. de-registration by periodical registration

Definitions

  • the present invention relates to an apparatus, a method, a system, and a computer program product related to mobile communication networks. More particularly, the present invention relates to an apparatus, a method, a system, and a computer program product embodying a concept of re-registration in case of HSS outage or in case HSS is not reachable.
  • WiFiTM Wireless Fidelity IP Multimedia Subsystem is a service platform introduced by 3GPP to provide IP based multimedia services to users with IP access.
  • the IMS core comprises the Home Subscriber Server (HSS) and Call Session Control Function (CSCF).
  • HSS Home Subscriber Server
  • CSCF Call Session Control Function
  • the HSS is a database application, which stores both static information like user profile and dynamic information like IMS user registration status and the Serving CSCF (S-CSCF) address hosting an IMS user.
  • S-CSCF Serving CSCF
  • CSCF may be split into P-CSCF, l-CSCF, and S-CSCF.
  • P-CSCF is in contact with the UE and may be located in the home network or in the visited network. For a UE, it does not change during the duration of its registration.
  • the address of l-CSCF is published such that remote servers can find it, e.g. for queries to HSS.
  • l-CSCF retrieves the address of S-CSCF for a UE at SIP registration.
  • S-CSCF may perform session control. It retrieves user profiles from HSS, e.g. via Cx and Dx interfaces, which are Diameter based. It decides on the AS to which a SIP request is forwarded, and may provide routing services.
  • the HSS is a single point of failure in the IMS system and no restoration procedure is defined by 3GPP for the HSS. If the HSS is out of service, no IMS procedure involving HSS is successful, e.g. IMS registration procedure or message routing via Interrogating CSCF (I- CSCF).
  • I- CSCF Interrogating CSCF
  • the re-registration procedure also involves the HSS and is shown in Fig. 1 .
  • the UE may send a registration request to P-CSCF (1 .), which is forwarded to l-CSCF of the home network of the UE (2.).
  • I- CSCF queries HSS over Cx interface (3.), which responds (4.) providing the address of S- CSCF.
  • l-CSCF forwards the registration request to the S-CSCF determined by HSS (5.).
  • S-CSCF requests further subscriber information from HSS and informs HSS that the subscriber is registered at S-CSCF (6.), both over Cx interface.
  • HSS responds accordingly (7.).
  • S-CSCF gives back ok to l-CSCF (9.), which is forwarded to P-CSCF (10.), and from there to UE (1 1 .).
  • registration is completed.
  • An IMS registration has a lifetime, which is set at each registration procedure. If the user wants to continue its IMS communication, he has to extend its IMS registration ("re-register”) before it expires.
  • the HSS will return the S-CSCF address of the IMS user in message #4. If the HSS is unavailable, the re-registration procedure will fail because the l-CSCF cannot get the S- CSCF address from the HSS. In this case the existing IMS registration cannot be extended and will expire. After the expiration of IMS registration no IMS service can be provided for the IMS user anymore. Note that contacting the HSS during the re-registration procedure is optional for the S-CSCF.
  • the l-CSCF shall reject the REGISTER request in case of HSS unavailability, and no IMS service can be provided to the IMS user after the expiration of the existing registration at the S-CSCF.
  • a backup HSS containing static information of IMS users can be deployed in the IMS system, which is used by the CSCFs if the primary HSS is out of service.
  • the backup HSS cannot provide the address of the S-CSCF, which hosts a certain user (i.e., to which the user is registered).
  • the disadvantage of such a solution is that additional network capacities must be provided in the network, which leads to more capital expenditure.
  • the backup HSS only has the static information of the user. The dynamic information stored in the primary HSS is not available. So the backup HSS cannot completely replace the primary HSS.
  • an apparatus comprising checking means adapted to check if, in response to an issued second registration request for a user, an indication is received that a home subscriber server is not available, wherein the second registration request is based on a received first registration request for the user; retrieving means adapted to retrieve an address of a serving call session control function from a data repository different from the home subscriber server if the indication is received that the home subscriber server is not available, wherein, according to the data repository, the user is registered with the serving call session control function; issuing means adapted to issue a third registration request for the user to the serving call session control function, wherein the third registration request is based on the first registration request.
  • the apparatus may further comprise adding means adapted to add a limiting information to the third registration request, wherein the limiting information indicates that the address of the serving call session control function is not provided by the home subscriber server, wherein the issuing means may be further adapted to issue the third registration request with the limiting information added.
  • the apparatus may comprise the data repository.
  • the apparatus may further comprise obtaining means adapted to obtain, from an earlier response to a forwarded earlier registration request for the user, the address of the serving call session control function, wherein the earlier response was received earlier than the first registration request; and storing means adapted to store a data pair comprising an identification of the user and the address of the serving call session control function in the data repository.
  • an apparatus comprising monitoring means adapted to monitor if a registration request for a user comprising a limiting information is received from a proxy call session control function, wherein the limiting information indicates that the address of the apparatus used for the registration request is not provided by a home subscriber server; extending means adapted to extend a service control for the user if the registration request is received.
  • the monitoring means may be adapted to monitor if the registration request for the terminal device is received only when the service control is about to expire.
  • the extending means may be adapted to extend the service control for one or more first services, wherein the home subscriber server may be not available for successful execution of each of the one or more first services.
  • the apparatus may further comprise terminating means adapted to terminate the service control for one or more second services, wherein the home subscriber server has to be available for successful execution of each of the second services.
  • the apparatus may further comprise checking means adapted to check if the apparatus performs the service control for the user; preventing means adapted to prevent the extending means from extending the service control for the user if the apparatus does not perform the service control for the user when the registration request is received.
  • an apparatus comprising evaluating means adapted to evaluate whether a second response to a query for a serving call session control function for a user is received from a home subscriber server, wherein the query is based on a first registration request for the user received from a proxy call session control function; composing means adapted to compose a first response to the first registration request, wherein, if the second response is not received from the home subscriber server, the first response comprises an indication that the home subscriber server is not available; providing means adapted to provide the first response to the proxy call session control function in response to the first registration request.
  • an apparatus comprising checking processor adapted to check if, in response to an issued second registration request for a user, an indication is received that a home subscriber server is not available, wherein the second registration request is based on a received first registration request for the user; retrieving processor adapted to retrieve an address of a serving call session control function from a data repository different from the home subscriber server if the indication is received that the home subscriber server is not available, wherein, according to the data repository, the user is registered with the serving call session control function; issuing processor adapted to issue a third registration request for the user to the serving call session control function, wherein the third registration request is based on the first registration request.
  • the apparatus may further comprise adding processor adapted to add a limiting information to the third registration request, wherein the limiting information indicates that the address of the serving call session control function is not provided by the home subscriber server, wherein the issuing processor may be further adapted to issue the third registration request with the limiting information added.
  • the apparatus may comprise the data repository.
  • the apparatus may further comprise obtaining processor adapted to obtain, from an earlier response to a forwarded earlier registration request for the user, the address of the serving call session control function, wherein the earlier response was received earlier than the first registration request; and storing processor adapted to store a data pair comprising an identification of the user and the address of the serving call session control function in the data repository.
  • an apparatus comprising monitoring processor adapted to monitor if a registration request for a user comprising a limiting information is received from a proxy call session control function, wherein the limiting information indicates that the address of the apparatus used for the registration request is not provided by a home subscriber server; extending processor adapted to extend a service control for the user if the registration request is received.
  • the monitoring processor may be adapted to monitor if the registration request for the terminal device is received only when the service control is about to expire.
  • the extending processor may be adapted to extend the service control for one or more first services, wherein the home subscriber server may be not available for successful execution of each of the one or more first services.
  • the apparatus may further comprise terminating processor adapted to terminate the service control for one or more second services, wherein the home subscriber server has to be available for successful execution of each of the second services.
  • the apparatus may further comprise checking processor adapted to check if the apparatus performs the service control for the user; preventing processor adapted to prevent the extending processor from extending the service control for the user if the apparatus does not perform the service control for the user when the registration request is received.
  • an apparatus comprising evaluating processor adapted to evaluate whether a second response to a query for a serving call session control function for a user is received from a home subscriber server, wherein the query is based on a first registration request for the user received from a proxy call session control function; composing processor adapted to compose a first response to the first registration request, wherein, if the second response is not received from the home subscriber server, the first response comprises an indication that the home subscriber server is not available; providing processor adapted to provide the first response to the proxy call session control function in response to the first registration request.
  • the apparatus may be a call session control function of an internet protocol multimedia subsystem.
  • the internet protocol multimedia subsystem may belong to a communication network according to a third generation partnership project.
  • a method comprising checking if, in response to an issued second registration request for a user, an indication is received that a home subscriber server is not available, wherein the second registration request is based on a received first registration request for the user; retrieving an address of a serving call session control function from a data repository different from the home subscriber server if the indication is received that the home subscriber server is not available, wherein, according to the data repository, the user is registered with the serving call session control function; issuing a third registration request for the user to the serving call session control function, wherein the third registration request is based on the first registration request.
  • the method may further comprise adding a limiting information to the third registration request, wherein the limiting information indicates that the address of the serving call session control function is not provided by the home subscriber server, wherein the issuing is further adapted to issue the third registration request with the limiting information added.
  • An apparatus performing the method may comprise the data repository.
  • the method may further comprise obtaining, from an earlier response to a forwarded earlier registration request for the user, the address of the serving call session control function, wherein the earlier response was received earlier than the first registration request; and storing a data pair comprising an identification of the user and the address of the serving call session control function in the data repository.
  • a method comprising monitoring if a registration request for a user comprising a limiting information is received from a proxy call session control function, wherein the limiting information indicates that the address of an apparatus performing the method used for the registration request is not provided by a home subscriber server; extending a service control for the user if the registration request is received.
  • the monitoring if the registration request for the terminal device is received may be performed only when the service control is about to expire.
  • the extending may be adapted to extend the service control for one or more first services, wherein the home subscriber server may be not available for successful execution of each of the one or more first services.
  • the method may further comprise terminating the service control for one or more second services, wherein the home subscriber server has to be available for successful execution of each of the second services.
  • the method may further comprise checking if the apparatus performs the service control for the user; preventing the extending the service control for the user if the apparatus does not perform the service control for the user when the registration request is received.
  • a method comprising evaluating whether a second response to a query for a serving call session control function for a user is received from a home subscriber server, wherein the query is based on a first registration request for the user received from a proxy call session control function; composing a first response to the first registration request, wherein, if the second response is not received from the home subscriber server, the first response comprises an indication that the home subscriber server is not available; providing the first response to the proxy call session control function in response to the first registration request.
  • Each of the methods of the seventh to ninth aspects may be a method of a call session control function.
  • a computer program product comprising a set of instructions which, when executed on an apparatus, is configured to cause the apparatus to carry out the method according to any of the seventh to ninth aspects.
  • the computer program product may be embodied as a computer readable medium or directly loadable into a computer. According to some embodiments of the invention, at least one of the following advantages may be achieved:
  • the solution is applicable not only to (full or partial) HSS outage but also in case of communication problems between l-CSCF and HSS;
  • the solution is transparent for the UE
  • Fig. 1 shows a re-registration message flow according to 3GPP TS 23.228, Fig. 5.2;
  • Fig. 2 shows a message flow according to an embodiment of the invention
  • Fig. 3 shows a message flow according to an alternative option
  • Fig. 4 shows a message flow for an originating request according to an embodiment of the invention
  • Fig. 5 shows a message flow for service execution according to an embodiment of the invention
  • Fig. 6 shows a message flow for an application server sending an initial request according to an embodiment of the invention
  • Fig. 7 shows an apparatus according to an embodiment of the invention
  • Fig. 8 shows a method according to an embodiment of the invention
  • Fig. 9 shows an apparatus according to an embodiment of the invention
  • Fig. 10 shows a method according to an embodiment of the invention
  • Fig. 1 1 shows an apparatus according to an embodiment of the invention
  • Fig. 12 shows a method according to an embodiment of the invention.
  • Fig. 13 shows an apparatus according to an embodiment of the invention.
  • the registration information stored in the P- CSCF is used to deliver the re-REGISTER request to the S-CSCF hosting the IMS user so that the re-REGISTER request can be successfully processed by the S-CSCF.
  • the registration of the user will not expire.
  • the user specific user profile stored in the S-CSCF can still be used for IMS services, as long as the SIP requests can be routed via the S- CSCF, e.g. originating request issued by the UE.
  • a first option is implemented (Option-1 , see Fig. 2):
  • the P-CSCF just forwards the re-REGISTER request to the l-CSCF as required by the current 3GPP specification (1., 2.).
  • the I- CSCF rejects the re-REGISTER request (4.) as specified by 3GPP.
  • the l-CSCF inserts an indication of the unavailability of the HSS in the negative response to the re-REGISTER request (e.g. the 480 Temporary Unavailable could be used, which is typically used by 3GPP for this situation).
  • the P-CSCF recognizes this indication and retrieves the S-CSCF address stored in the registration information for this IMS user.
  • the P-CSCF then sends the re- REGISTER request to the S-CSCF directly (5.).
  • the re-REGISTER request to the S-CSCF may comprise an indication for limited service to inform the S-CSCF about the re-use of the S-CSCF address for the re-REGISTER request.
  • the S-CSCF Upon receipt of "ok" from the S-CSCF (6., 7.), the registration of the S-CSCF for the particular user is extended in the P-CSCF and UE.
  • the S-CSCF address stored in the P-CSCF is normally used for originating non- REGISTER request sent by UE. So the indication about the reuse may help the S-CSCF deal with the re-REGISTER request.
  • the advantage of this option is that the P-CSCF need not check whether the REGISTER request is a re-REGISTER request or not when it forwards the REGISTER request to the I- CSCF. There may not be any indication about re-registration in the re-REGISTER request, that is, a re-REGISTER request may not be distinguishable from an initial REGISTER request. If P-CSCF wants to distinguish initial REGISTER and re-REGISTER, it has to check its internal database to know whether the REGISTER request is an initial REGISTER or a re-REGISTER request. So this option is particularly useful if P-CSCF need not to check the type of REGISTER request for any other purpose.
  • a second option is implemented (Option-2, see Fig. 3): With this option, it is assumed that P-CSCF knows that the received REGISTER request is a re-REGISTER request, e.g. because it has checked the P-CSCF internal database for other purpose, or because the re-REGISTER request is different from an initial REGISTER request. Step 1 from UE to P-CSCF is the same as according to the prior art. According to the second option, the P-CSCF retrieves the S-CSCF address from the registration information for this user. It then includes this address in the re-REGISTER request to the I- CSCF (2.).
  • the l-CSCF cannot retrieve the S-CSCF address from the HSS. Then, the l-CSCF forwards the re-REGISTER request to the S-CSCF address embedded in the re-REGISTER request (4.).
  • an indication is also inserted by the l-CSCF to inform the S-CSCF about the re-use of the S-CSCF address stored at the P-CSCF. This indication may be useful for same reason as described for Option-1.
  • the advantage compared to the current 3GPP specification is that the re-registration will be successful even if the HSS is unavailable, if the S-CSCF accepts the re-registration without any interworking with HSS.
  • user specific IMS service can still be provided for the IMS user if the related SIP request can still be delivered to the S-CSCF, e.g. any SIP originating request sent by the UE, as shown in the example of Fig. 4.
  • UE sends SIP INVITE message (i.e. a service request) to P-CSCF (1.).
  • P-CSCF retrieves S-CSCF address from its data repository (registration data), and forwards the same or a modified INVITE message to S-CSCF (2.).
  • S-CSCF performs service control. E.g. it may forward the same or another modified INVITE message to AS (3.).
  • Successful execution of the respective service requests is acknowledged by OK (4., 5., 6.).
  • Fig. 5 shown another example of service control which may be executed even if HSS is not available.
  • S-CSCF executes service control by forwarding the INVITE message to AS (2.), where the service logic is executed.
  • the service logic requires further input from another entity.
  • S-CSCF issues a service request (INVITE message) to S-CSCF (3.), which S-CSCF forwards to another entity (4.), such as another AS or the UE.
  • S-CSCF may also modify the service request before forwarding.
  • the acknowledgement (“OK") comprising the requested information is returned via S-CSCF to AS (5., 6.), where the execution of the service logic is continued.
  • OK successful execution of the first service request is acknowledged by OK (7., 8.).
  • Fig. 6 shows another example, wherein AS caches the S-CSCF address for the IMS user.
  • S-CSCF executes service control for registration of the IMS user and sends REGISTER request to AS (1 .) to register the user at AS.
  • AS caches S-CSCF address related to the user and confirms by OK (2.).
  • OK If a service logic is executed on AS, it may request further input related to the user.
  • AS sends INVITE (first service request) to the S-CSCF whose address is cached for the user (3.).
  • S-CSCF some service logic may be executed. It may also forward a (modified or unmodified) INVITE message to another entity (4.) such as the UE or another AS.
  • Successful execution of the first service request is acknowledged by OK (5., 6.).
  • the P-CSCF caches the S-CSCF address serving the IMS user, the P-CSCF is still able to deliver all originating requests to the correct S-CSCF (see e.g. Fig. 4).
  • the AS is always able to send a SIP request received from the S-CSCF back to the S-CSCF after service execution because the S-CSCF inserted its address in the SIP request.
  • the unavailable HSS will not have any impact on the message routing for this scenario (see e.g. Fig. 5).
  • an AS caches the S-CSCF address for the IMS user, this AS can also issue new SIP request to the correct S-CSCF (see e.g. Fig. 6).
  • IMS operation there are certain limitations related to IMS operation, which are mainly caused due to the lack of interworking with HSS: a) The S-CSCF is not able to download new credential from HSS for IMS re- authentication, which is mainly required for IMS registrations with security association. As the registration is still protected by the existing security association between the UE and IMS core, no significant security risk is introduced by this limitation. For authentication schema where the credential downloaded during the initial registration can still be used, there is no limitation for authentication. b) The S-CSCF cannot update IMS restoration information in HSS if there is any change.
  • the l-CSCF is not able to retrieve the S-CSCF address or server capabilities from the HSS. This will cause that the l-CSCF is not able to deliver a SIP request to the S-CSCF hosting the related IMS user.
  • the l-CSCF is also not able to start S- CSCF re-selection based on server capabilities.
  • AS not caching S-CSCF address is not able to send initial request (INVITE) to S- CSCF hosting the related IMS user.
  • Embodiments of the invention are described for a case that the HSS is unavailable. This includes cases like full HSS outage and partial HSS outage, and cases where HSS and I- CSCF cannot communicate with each other, e.g. due to a link outage, too poor link quality, wrong addressing on either side, etc..
  • HSS and l-CSCF cannot communicate with each other but HSS and S-CSCF and/or HSS and AS can communicate with each other (e.g. if certain links from the l-CSCF fail).
  • the respective restrictions outlined above do not apply: If HSS and S-CSCF may still communicate with each other, restrictions a) and b) do not apply, and if HSS and AS may still communicate with each other, restrictions d) and e) do not apply. Therefore, in some embodiments, S-CSCF may try to communicate with HSS even if it received the indication of the unavailability of the HSS.
  • Fig. 7 shows an apparatus according to an embodiment of the invention.
  • the apparatus may be a P-CSCF, or an element thereof.
  • Fig. 8 shows a method according to an embodiment of the invention.
  • the apparatus according to Fig. 7 may perform the method of Fig. 8 but is not limited to this method.
  • the method of Fig. 8 may be performed by the apparatus of Fig. 7 but is not limited to being performed by this apparatus.
  • the apparatus comprises checking means 10, retrieving means 20, and issuing means 30.
  • the checking means 10 checks if an indication that a home subscriber server is not available is received (S10).
  • the indication is received in response to an issued second registration request for a user.
  • the second registration request is based on a received first registration request for the user.
  • the second registration request may be the forwarded first registration request, or it may be a modified first registration request.
  • the retrieving means 20 retrieves an address of a serving call session control function from a data repository if the indication is received that the home subscriber server is not available (S20). The address is retrieved such that, according to the data repository, the user is registered with the serving call session control function having the address.
  • the data repository is different from the home subscriber server. In particular, the data repository may belong to the apparatus.
  • the issuing means 30 issues a third registration request for the user to the serving call session control function (S30).
  • the third registration request is based on the first registration request.
  • the third registration request may be the forwarded first registration request, or it may be a modified first registration request.
  • Fig. 9 shows an apparatus according to an embodiment of the invention.
  • the apparatus may be a S-CSCF, or an element thereof.
  • Fig. 10 shows a method according to an embodiment of the invention.
  • the apparatus according to Fig. 9 may perform the method of Fig. 10 but is not limited to this method.
  • the method of Fig. 10 may be performed by the apparatus of Fig. 9 but is not limited to being performed by this apparatus.
  • the apparatus comprises monitoring means 1 10 and extending means 120.
  • the monitoring means 1 10 monitors if a registration request for a user comprising a limiting information is received from a proxy call session control function (S1 10).
  • the limiting information indicates that the address of the apparatus used for the registration request is not provided by a home subscriber server.
  • the monitoring means monitors for the registration request with the limiting information only when the registration of the user is about to expire (e.g. the last 5 minutes, or 3 minutes, or 1 minute before expiration).
  • the extending means 120 extends a service control for the user if the registration request is received (S120). In some embodiments, it extends registration (only) for those services of the user for which successful execution the HSS is not required. Registrations to services requiring HSS for successful execution may be terminated. In addition, in some embodiments, it may be checked if the user is registered when the registration request is received. In these embodiments, the registration is only extended if the user is registered when the registration request is received.
  • Fig. 1 1 shows an apparatus according to an embodiment of the invention.
  • the apparatus may be a l-CSCF, or an element thereof.
  • Fig. 12 shows a method according to an embodiment of the invention.
  • the apparatus according to Fig. 1 1 may perform the method of Fig. 12 but is not limited to this method.
  • the method of Fig. 12 may be performed by the apparatus of Fig. 1 1 but is not limited to being performed by this apparatus.
  • the apparatus comprises evaluating means 210, composing means 220, and providing means 230.
  • the evaluating means 210 evaluates whether a second response to a query for a serving call session control function for a user is received from a home subscriber server (S210).
  • the query is directed to the home subscriber server and is based on a first registration request for the user.
  • the first registration request is received from a proxy call session control function.
  • the second registration request may be the forwarded first registration request, or it may be a modified first registration request.
  • the composing means 220 composes a first response to the first registration request (S220). If the second response is not received from the home subscriber server (i.e. HSS is not available), the first response comprises an indication that the home subscriber server is not available.
  • the providing means 230 provides the first response to the proxy call session control function in response to the first registration request (S230).
  • Fig. 13 shows an apparatus according to an embodiment of the invention.
  • the apparatus comprises at least one processor 310 and at least one memory 320 including computer program code.
  • the at least one processor 310, with the at least one memory 320 and the computer program code, is arranged to cause the apparatus to at least perform any of the methods of Figs. 8, 10, and 12.
  • Embodiments of the invention may be employed in IMS, e.g. of a 3GPP network of any generation (3G, 4G, 5G,). They may be employed also in other networks with corresponding functions of call session control functions like CDMA, EDGE, UMTS, LTE, LTE-A, WiFi networks, etc..
  • a terminal (device) or a user equipment may be a mobile phone, a smart phone, a PDA, a laptop or any other terminal which may be attached to the respective network.
  • a registration may expire after some time without activity in the session.
  • the provided/received information may comprise one or more pieces of information related to different meanings.
  • One information may be transmitted in one or plural messages.
  • Names of network elements, protocols, and methods are based on current standards. In other versions or other technologies, the names of these network elements and/or protocols and/or methods may be different, as long as they provide a corresponding functionality. If not otherwise stated or otherwise made clear from the context, the statement that two entities are different means that they perform different functions. It does not necessarily mean that they are based on different hardware. That is, each of the entities described in the present description may be based on a different hardware, or some or all of the entities may be based on the same hardware.
  • exemplary embodiments of the present invention provide, for example a call session control function, or a component thereof, an apparatus embodying the same, a method for controlling and/or operating the same, and computer program(s) controlling and/or operating the same as well as mediums carrying such computer program(s) and forming computer program product(s).
  • Implementations of any of the above described blocks, apparatuses, systems, techniques or methods include, as non limiting examples, implementations as hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof. It is to be understood that what is described above is what is presently considered the preferred embodiments of the present invention. However, it should be noted that the description of the preferred embodiments is given by way of example only and that various modifications may be made without departing from the scope of the invention as defined by the appended claims.

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  • Telephonic Communication Services (AREA)

Abstract

It is provided a method, comprising checking if, in response to an issued second registration request for a user, an indication is received that a home subscriber server is not available, wherein the second registration request is based on a received first registration request for the user; retrieving an address of a serving call session control function from a data repository different from the home subscriber server if the indication is received that the home subscriber server is not available, wherein, according to the data repository, the user is registered with the serving call session control function; issuing a third registration request for the user to the serving call session control function, wherein the third registration request is based on the first registration request.

Description

Re-registration in case of HSS outage
Field of the invention
The present invention relates to an apparatus, a method, a system, and a computer program product related to mobile communication networks. More particularly, the present invention relates to an apparatus, a method, a system, and a computer program product embodying a concept of re-registration in case of HSS outage or in case HSS is not reachable.
Background of the invention
Abbreviations
3G 3rd generation
3GPP 3rd Generation Partnership Project
4G 4th generation
5G 5th generation
AS Application Server
CDMA Code Division Multiple Access
CSCF Call Session Control Function
EDGE Enhanced Data rates for Global Evolution
HSS Home Subscriber Server
l-CSCF Interrogating CSCF
IMS IP Multimedia Subsystem
IP Internet Protocol
LTE™ Long Term Evolution
LTE-A™ Long Term Evolution- Advanced
P-CSCF Proxy-CSCF
S-CSCF Serving CSCF
SIP Session Initiation Protocol
UE User Equipment
UMTS Universal Mobile Telecommunication System
WCDMA Wideband Code Division Multiplex Access
WiFi™ Wireless Fidelity IP Multimedia Subsystem (IMS) is a service platform introduced by 3GPP to provide IP based multimedia services to users with IP access. The IMS core comprises the Home Subscriber Server (HSS) and Call Session Control Function (CSCF). The HSS is a database application, which stores both static information like user profile and dynamic information like IMS user registration status and the Serving CSCF (S-CSCF) address hosting an IMS user.
CSCF may be split into P-CSCF, l-CSCF, and S-CSCF. P-CSCF is in contact with the UE and may be located in the home network or in the visited network. For a UE, it does not change during the duration of its registration. The address of l-CSCF is published such that remote servers can find it, e.g. for queries to HSS. In particular, l-CSCF retrieves the address of S-CSCF for a UE at SIP registration. S-CSCF may perform session control. It retrieves user profiles from HSS, e.g. via Cx and Dx interfaces, which are Diameter based. It decides on the AS to which a SIP request is forwarded, and may provide routing services.
The HSS is a single point of failure in the IMS system and no restoration procedure is defined by 3GPP for the HSS. If the HSS is out of service, no IMS procedure involving HSS is successful, e.g. IMS registration procedure or message routing via Interrogating CSCF (I- CSCF).
If an IMS user is registered in IMS, the re-registration procedure also involves the HSS and is shown in Fig. 1 . E.g., as in the case of initial registration, the UE may send a registration request to P-CSCF (1 .), which is forwarded to l-CSCF of the home network of the UE (2.). I- CSCF queries HSS over Cx interface (3.), which responds (4.) providing the address of S- CSCF. Then, l-CSCF forwards the registration request to the S-CSCF determined by HSS (5.). S-CSCF requests further subscriber information from HSS and informs HSS that the subscriber is registered at S-CSCF (6.), both over Cx interface. HSS responds accordingly (7.). Then, S-CSCF gives back ok to l-CSCF (9.), which is forwarded to P-CSCF (10.), and from there to UE (1 1 .). Thus, registration is completed.
An IMS registration has a lifetime, which is set at each registration procedure. If the user wants to continue its IMS communication, he has to extend its IMS registration ("re-register") before it expires.
In case of re-registration, because a S-CSCF has been already assigned to a registered user, the HSS will return the S-CSCF address of the IMS user in message #4. If the HSS is unavailable, the re-registration procedure will fail because the l-CSCF cannot get the S- CSCF address from the HSS. In this case the existing IMS registration cannot be extended and will expire. After the expiration of IMS registration no IMS service can be provided for the IMS user anymore. Note that contacting the HSS during the re-registration procedure is optional for the S-CSCF.
With the current 3GPP specification, the l-CSCF shall reject the REGISTER request in case of HSS unavailability, and no IMS service can be provided to the IMS user after the expiration of the existing registration at the S-CSCF.
A backup HSS containing static information of IMS users can be deployed in the IMS system, which is used by the CSCFs if the primary HSS is out of service. However, the backup HSS cannot provide the address of the S-CSCF, which hosts a certain user (i.e., to which the user is registered).
The disadvantage of such a solution is that additional network capacities must be provided in the network, which leads to more capital expenditure. Furthermore the backup HSS only has the static information of the user. The dynamic information stored in the primary HSS is not available. So the backup HSS cannot completely replace the primary HSS.
Summary of the invention It is an object of the present invention to improve the prior art. In detail, it is an object to overcome at least some of the problems due to the HSS being a single point of failure.
According to a first aspect of the invention, there is provided an apparatus, comprising checking means adapted to check if, in response to an issued second registration request for a user, an indication is received that a home subscriber server is not available, wherein the second registration request is based on a received first registration request for the user; retrieving means adapted to retrieve an address of a serving call session control function from a data repository different from the home subscriber server if the indication is received that the home subscriber server is not available, wherein, according to the data repository, the user is registered with the serving call session control function; issuing means adapted to issue a third registration request for the user to the serving call session control function, wherein the third registration request is based on the first registration request.
The apparatus may further comprise adding means adapted to add a limiting information to the third registration request, wherein the limiting information indicates that the address of the serving call session control function is not provided by the home subscriber server, wherein the issuing means may be further adapted to issue the third registration request with the limiting information added. The apparatus may comprise the data repository.
The apparatus may further comprise obtaining means adapted to obtain, from an earlier response to a forwarded earlier registration request for the user, the address of the serving call session control function, wherein the earlier response was received earlier than the first registration request; and storing means adapted to store a data pair comprising an identification of the user and the address of the serving call session control function in the data repository.
According to a second aspect of the invention, there is provided an apparatus, comprising monitoring means adapted to monitor if a registration request for a user comprising a limiting information is received from a proxy call session control function, wherein the limiting information indicates that the address of the apparatus used for the registration request is not provided by a home subscriber server; extending means adapted to extend a service control for the user if the registration request is received.
In the apparatus, the monitoring means may be adapted to monitor if the registration request for the terminal device is received only when the service control is about to expire.
In the apparatus, the extending means may be adapted to extend the service control for one or more first services, wherein the home subscriber server may be not available for successful execution of each of the one or more first services.
The apparatus may further comprise terminating means adapted to terminate the service control for one or more second services, wherein the home subscriber server has to be available for successful execution of each of the second services.
The apparatus may further comprise checking means adapted to check if the apparatus performs the service control for the user; preventing means adapted to prevent the extending means from extending the service control for the user if the apparatus does not perform the service control for the user when the registration request is received. According to a third aspect of the invention, there is provided an apparatus, comprising evaluating means adapted to evaluate whether a second response to a query for a serving call session control function for a user is received from a home subscriber server, wherein the query is based on a first registration request for the user received from a proxy call session control function; composing means adapted to compose a first response to the first registration request, wherein, if the second response is not received from the home subscriber server, the first response comprises an indication that the home subscriber server is not available; providing means adapted to provide the first response to the proxy call session control function in response to the first registration request.
According to a fourth aspect of the invention, there is provided an apparatus, comprising checking processor adapted to check if, in response to an issued second registration request for a user, an indication is received that a home subscriber server is not available, wherein the second registration request is based on a received first registration request for the user; retrieving processor adapted to retrieve an address of a serving call session control function from a data repository different from the home subscriber server if the indication is received that the home subscriber server is not available, wherein, according to the data repository, the user is registered with the serving call session control function; issuing processor adapted to issue a third registration request for the user to the serving call session control function, wherein the third registration request is based on the first registration request.
The apparatus may further comprise adding processor adapted to add a limiting information to the third registration request, wherein the limiting information indicates that the address of the serving call session control function is not provided by the home subscriber server, wherein the issuing processor may be further adapted to issue the third registration request with the limiting information added.
The apparatus may comprise the data repository.
The apparatus may further comprise obtaining processor adapted to obtain, from an earlier response to a forwarded earlier registration request for the user, the address of the serving call session control function, wherein the earlier response was received earlier than the first registration request; and storing processor adapted to store a data pair comprising an identification of the user and the address of the serving call session control function in the data repository.
According to a fifth aspect of the invention, there is provided an apparatus, comprising monitoring processor adapted to monitor if a registration request for a user comprising a limiting information is received from a proxy call session control function, wherein the limiting information indicates that the address of the apparatus used for the registration request is not provided by a home subscriber server; extending processor adapted to extend a service control for the user if the registration request is received.
In the apparatus, the monitoring processor may be adapted to monitor if the registration request for the terminal device is received only when the service control is about to expire.
In the apparatus, the extending processor may be adapted to extend the service control for one or more first services, wherein the home subscriber server may be not available for successful execution of each of the one or more first services.
The apparatus may further comprise terminating processor adapted to terminate the service control for one or more second services, wherein the home subscriber server has to be available for successful execution of each of the second services.
The apparatus may further comprise checking processor adapted to check if the apparatus performs the service control for the user; preventing processor adapted to prevent the extending processor from extending the service control for the user if the apparatus does not perform the service control for the user when the registration request is received.
According to a sixth aspect of the invention, there is provided an apparatus, comprising evaluating processor adapted to evaluate whether a second response to a query for a serving call session control function for a user is received from a home subscriber server, wherein the query is based on a first registration request for the user received from a proxy call session control function; composing processor adapted to compose a first response to the first registration request, wherein, if the second response is not received from the home subscriber server, the first response comprises an indication that the home subscriber server is not available; providing processor adapted to provide the first response to the proxy call session control function in response to the first registration request. The apparatus according to any of the first to sixth aspects may be a call session control function of an internet protocol multimedia subsystem. The internet protocol multimedia subsystem may belong to a communication network according to a third generation partnership project.
According to a seventh aspect of the invention, there is provided a method, comprising checking if, in response to an issued second registration request for a user, an indication is received that a home subscriber server is not available, wherein the second registration request is based on a received first registration request for the user; retrieving an address of a serving call session control function from a data repository different from the home subscriber server if the indication is received that the home subscriber server is not available, wherein, according to the data repository, the user is registered with the serving call session control function; issuing a third registration request for the user to the serving call session control function, wherein the third registration request is based on the first registration request.
The method may further comprise adding a limiting information to the third registration request, wherein the limiting information indicates that the address of the serving call session control function is not provided by the home subscriber server, wherein the issuing is further adapted to issue the third registration request with the limiting information added.
An apparatus performing the method may comprise the data repository. The method may further comprise obtaining, from an earlier response to a forwarded earlier registration request for the user, the address of the serving call session control function, wherein the earlier response was received earlier than the first registration request; and storing a data pair comprising an identification of the user and the address of the serving call session control function in the data repository.
According to an eighth aspect of the invention, there is provided a method, comprising monitoring if a registration request for a user comprising a limiting information is received from a proxy call session control function, wherein the limiting information indicates that the address of an apparatus performing the method used for the registration request is not provided by a home subscriber server; extending a service control for the user if the registration request is received.
In the method, the monitoring if the registration request for the terminal device is received may be performed only when the service control is about to expire.
In the method, the extending may be adapted to extend the service control for one or more first services, wherein the home subscriber server may be not available for successful execution of each of the one or more first services.
The method may further comprise terminating the service control for one or more second services, wherein the home subscriber server has to be available for successful execution of each of the second services. The method may further comprise checking if the apparatus performs the service control for the user; preventing the extending the service control for the user if the apparatus does not perform the service control for the user when the registration request is received.
According to a ninth aspect of the invention, there is provided a method, comprising evaluating whether a second response to a query for a serving call session control function for a user is received from a home subscriber server, wherein the query is based on a first registration request for the user received from a proxy call session control function; composing a first response to the first registration request, wherein, if the second response is not received from the home subscriber server, the first response comprises an indication that the home subscriber server is not available; providing the first response to the proxy call session control function in response to the first registration request.
Each of the methods of the seventh to ninth aspects may be a method of a call session control function.
According to a tenth aspect of the invention, there is provided a computer program product comprising a set of instructions which, when executed on an apparatus, is configured to cause the apparatus to carry out the method according to any of the seventh to ninth aspects. The computer program product may be embodied as a computer readable medium or directly loadable into a computer. According to some embodiments of the invention, at least one of the following advantages may be achieved:
- user experience is improved;
service utilization may be extended;
- service usage may be enhanced;
- security is not compromised;
- the solution is applicable not only to (full or partial) HSS outage but also in case of communication problems between l-CSCF and HSS;
the solution is transparent for the UE;
the solution is transparent for HSS;
capital expenditure is reduced.
It is to be understood that any of the above modifications can be applied singly or in combination to the respective aspects to which they refer, unless they are explicitly stated as excluding alternatives.
Brief description of the drawings Further details, features, objects, and advantages are apparent from the following detailed description of the preferred embodiments of the present invention which is to be taken in conjunction with the appended drawings, wherein
Fig. 1 shows a re-registration message flow according to 3GPP TS 23.228, Fig. 5.2;
Fig. 2 shows a message flow according to an embodiment of the invention;
Fig. 3 shows a message flow according to an alternative option;
Fig. 4 shows a message flow for an originating request according to an embodiment of the invention;
Fig. 5 shows a message flow for service execution according to an embodiment of the invention;
Fig. 6 shows a message flow for an application server sending an initial request according to an embodiment of the invention;
Fig. 7 shows an apparatus according to an embodiment of the invention;
Fig. 8 shows a method according to an embodiment of the invention;
Fig. 9 shows an apparatus according to an embodiment of the invention; Fig. 10 shows a method according to an embodiment of the invention;
Fig. 1 1 shows an apparatus according to an embodiment of the invention;
Fig. 12 shows a method according to an embodiment of the invention; and
Fig. 13 shows an apparatus according to an embodiment of the invention.
Detailed description of certain embodiments
Herein below, certain embodiments of the present invention are described in detail with reference to the accompanying drawings, wherein the features of the embodiments can be freely combined with each other unless otherwise described. However, it is to be expressly understood that the description of certain embodiments is given for by way of example only, and that it is by no way intended to be understood as limiting the invention to the disclosed details. Moreover, it is to be understood that the apparatus is configured to perform the corresponding method, although in some cases only the apparatus or only the method are described.
According to some embodiments of the invention, the registration information stored in the P- CSCF is used to deliver the re-REGISTER request to the S-CSCF hosting the IMS user so that the re-REGISTER request can be successfully processed by the S-CSCF. Thus, the registration of the user will not expire. The user specific user profile stored in the S-CSCF can still be used for IMS services, as long as the SIP requests can be routed via the S- CSCF, e.g. originating request issued by the UE.
Without the location query support of the HSS, not all requests for the affected IMS user can be routed via the S-CSCF. But this limited availability of services is better than the current 3GPP specification that re-registration will fail in case of HSS outage such that no service may be provided.
According to some embodiments, a first option is implemented (Option-1 , see Fig. 2):
With this option, the P-CSCF just forwards the re-REGISTER request to the l-CSCF as required by the current 3GPP specification (1., 2.). When the HSS is not available (3.), the I- CSCF rejects the re-REGISTER request (4.) as specified by 3GPP. The l-CSCF inserts an indication of the unavailability of the HSS in the negative response to the re-REGISTER request (e.g. the 480 Temporary Unavailable could be used, which is typically used by 3GPP for this situation). The P-CSCF recognizes this indication and retrieves the S-CSCF address stored in the registration information for this IMS user. The P-CSCF then sends the re- REGISTER request to the S-CSCF directly (5.). The re-REGISTER request to the S-CSCF may comprise an indication for limited service to inform the S-CSCF about the re-use of the S-CSCF address for the re-REGISTER request. Upon receipt of "ok" from the S-CSCF (6., 7.), the registration of the S-CSCF for the particular user is extended in the P-CSCF and UE. Note: the S-CSCF address stored in the P-CSCF is normally used for originating non- REGISTER request sent by UE. So the indication about the reuse may help the S-CSCF deal with the re-REGISTER request.
The advantage of this option is that the P-CSCF need not check whether the REGISTER request is a re-REGISTER request or not when it forwards the REGISTER request to the I- CSCF. There may not be any indication about re-registration in the re-REGISTER request, that is, a re-REGISTER request may not be distinguishable from an initial REGISTER request. If P-CSCF wants to distinguish initial REGISTER and re-REGISTER, it has to check its internal database to know whether the REGISTER request is an initial REGISTER or a re-REGISTER request. So this option is particularly useful if P-CSCF need not to check the type of REGISTER request for any other purpose.
According to some embodiments, a second option is implemented (Option-2, see Fig. 3): With this option, it is assumed that P-CSCF knows that the received REGISTER request is a re-REGISTER request, e.g. because it has checked the P-CSCF internal database for other purpose, or because the re-REGISTER request is different from an initial REGISTER request. Step 1 from UE to P-CSCF is the same as according to the prior art. According to the second option, the P-CSCF retrieves the S-CSCF address from the registration information for this user. It then includes this address in the re-REGISTER request to the I- CSCF (2.). In case of HSS unavailability (3.), the l-CSCF cannot retrieve the S-CSCF address from the HSS. Then, the l-CSCF forwards the re-REGISTER request to the S-CSCF address embedded in the re-REGISTER request (4.). In some embodiments, an indication is also inserted by the l-CSCF to inform the S-CSCF about the re-use of the S-CSCF address stored at the P-CSCF. This indication may be useful for same reason as described for Option-1.
The advantage of this option is that the l-CSCF forwards the re-REGISTER request directly to the S-CSCF. One message (4.: the negative response to the P-CSCF) can be saved compared to Option-1 .
For both Option-1 and Option-2, the advantage compared to the current 3GPP specification is that the re-registration will be successful even if the HSS is unavailable, if the S-CSCF accepts the re-registration without any interworking with HSS. Hence, user specific IMS service can still be provided for the IMS user if the related SIP request can still be delivered to the S-CSCF, e.g. any SIP originating request sent by the UE, as shown in the example of Fig. 4. In Fig. 4, UE sends SIP INVITE message (i.e. a service request) to P-CSCF (1.). P-CSCF retrieves S-CSCF address from its data repository (registration data), and forwards the same or a modified INVITE message to S-CSCF (2.). S-CSCF performs service control. E.g. it may forward the same or another modified INVITE message to AS (3.). Successful execution of the respective service requests is acknowledged by OK (4., 5., 6.).
Fig. 5 shown another example of service control which may be executed even if HSS is not available.
In Fig. 5, after having received the INVITE message (1.), S-CSCF executes service control by forwarding the INVITE message to AS (2.), where the service logic is executed. The service logic requires further input from another entity. Hence, it issues a service request (INVITE message) to S-CSCF (3.), which S-CSCF forwards to another entity (4.), such as another AS or the UE. S-CSCF may also modify the service request before forwarding. The acknowledgement ("OK") comprising the requested information is returned via S-CSCF to AS (5., 6.), where the execution of the service logic is continued. Finally, successful execution of the first service request is acknowledged by OK (7., 8.).
Fig. 6 shows another example, wherein AS caches the S-CSCF address for the IMS user. In Fig. 6, S-CSCF executes service control for registration of the IMS user and sends REGISTER request to AS (1 .) to register the user at AS. AS caches S-CSCF address related to the user and confirms by OK (2.). If a service logic is executed on AS, it may request further input related to the user. Thus, AS sends INVITE (first service request) to the S-CSCF whose address is cached for the user (3.). On S-CSCF, some service logic may be executed. It may also forward a (modified or unmodified) INVITE message to another entity (4.) such as the UE or another AS. Successful execution of the first service request is acknowledged by OK (5., 6.).
From service control point of view, there is no limitation at the S-CSCF because the S-CSCF still has the IMS user profile for service control, which was downloaded during initial registration. So for the following scenarios, an IMS service can be still be provided without available HSS:
• As the P-CSCF caches the S-CSCF address serving the IMS user, the P-CSCF is still able to deliver all originating requests to the correct S-CSCF (see e.g. Fig. 4).
• The AS is always able to send a SIP request received from the S-CSCF back to the S-CSCF after service execution because the S-CSCF inserted its address in the SIP request. The unavailable HSS will not have any impact on the message routing for this scenario (see e.g. Fig. 5).
• If an AS caches the S-CSCF address for the IMS user, this AS can also issue new SIP request to the correct S-CSCF (see e.g. Fig. 6). However, there are certain limitations related to IMS operation, which are mainly caused due to the lack of interworking with HSS: a) The S-CSCF is not able to download new credential from HSS for IMS re- authentication, which is mainly required for IMS registrations with security association. As the registration is still protected by the existing security association between the UE and IMS core, no significant security risk is introduced by this limitation. For authentication schema where the credential downloaded during the initial registration can still be used, there is no limitation for authentication. b) The S-CSCF cannot update IMS restoration information in HSS if there is any change.
c) The l-CSCF is not able to retrieve the S-CSCF address or server capabilities from the HSS. This will cause that the l-CSCF is not able to deliver a SIP request to the S-CSCF hosting the related IMS user. The l-CSCF is also not able to start S- CSCF re-selection based on server capabilities.
d) AS not caching S-CSCF address is not able to send initial request (INVITE) to S- CSCF hosting the related IMS user.
e) AS is not able to interwork with HSS to store or retrieve any information related to IMS service.
Embodiments of the invention are described for a case that the HSS is unavailable. This includes cases like full HSS outage and partial HSS outage, and cases where HSS and I- CSCF cannot communicate with each other, e.g. due to a link outage, too poor link quality, wrong addressing on either side, etc..
In some cases, it might happen that HSS and l-CSCF cannot communicate with each other but HSS and S-CSCF and/or HSS and AS can communicate with each other (e.g. if certain links from the l-CSCF fail). In these cases, the respective restrictions outlined above do not apply: If HSS and S-CSCF may still communicate with each other, restrictions a) and b) do not apply, and if HSS and AS may still communicate with each other, restrictions d) and e) do not apply. Therefore, in some embodiments, S-CSCF may try to communicate with HSS even if it received the indication of the unavailability of the HSS. Fig. 7 shows an apparatus according to an embodiment of the invention. The apparatus may be a P-CSCF, or an element thereof. Fig. 8 shows a method according to an embodiment of the invention. The apparatus according to Fig. 7 may perform the method of Fig. 8 but is not limited to this method. The method of Fig. 8 may be performed by the apparatus of Fig. 7 but is not limited to being performed by this apparatus.
The apparatus comprises checking means 10, retrieving means 20, and issuing means 30.
The checking means 10 checks if an indication that a home subscriber server is not available is received (S10). The indication is received in response to an issued second registration request for a user. The second registration request is based on a received first registration request for the user. E.g., the second registration request may be the forwarded first registration request, or it may be a modified first registration request.
The retrieving means 20 retrieves an address of a serving call session control function from a data repository if the indication is received that the home subscriber server is not available (S20). The address is retrieved such that, according to the data repository, the user is registered with the serving call session control function having the address. The data repository is different from the home subscriber server. In particular, the data repository may belong to the apparatus.
The issuing means 30 issues a third registration request for the user to the serving call session control function (S30). The third registration request is based on the first registration request. E.g., the third registration request may be the forwarded first registration request, or it may be a modified first registration request.
Fig. 9 shows an apparatus according to an embodiment of the invention. The apparatus may be a S-CSCF, or an element thereof. Fig. 10 shows a method according to an embodiment of the invention. The apparatus according to Fig. 9 may perform the method of Fig. 10 but is not limited to this method. The method of Fig. 10 may be performed by the apparatus of Fig. 9 but is not limited to being performed by this apparatus.
The apparatus comprises monitoring means 1 10 and extending means 120.
The monitoring means 1 10 monitors if a registration request for a user comprising a limiting information is received from a proxy call session control function (S1 10). The limiting information indicates that the address of the apparatus used for the registration request is not provided by a home subscriber server. In some embodiments, the monitoring means monitors for the registration request with the limiting information only when the registration of the user is about to expire (e.g. the last 5 minutes, or 3 minutes, or 1 minute before expiration).
The extending means 120 extends a service control for the user if the registration request is received (S120). In some embodiments, it extends registration (only) for those services of the user for which successful execution the HSS is not required. Registrations to services requiring HSS for successful execution may be terminated. In addition, in some embodiments, it may be checked if the user is registered when the registration request is received. In these embodiments, the registration is only extended if the user is registered when the registration request is received.
Fig. 1 1 shows an apparatus according to an embodiment of the invention. The apparatus may be a l-CSCF, or an element thereof. Fig. 12 shows a method according to an embodiment of the invention. The apparatus according to Fig. 1 1 may perform the method of Fig. 12 but is not limited to this method. The method of Fig. 12 may be performed by the apparatus of Fig. 1 1 but is not limited to being performed by this apparatus.
The apparatus comprises evaluating means 210, composing means 220, and providing means 230. The evaluating means 210 evaluates whether a second response to a query for a serving call session control function for a user is received from a home subscriber server (S210). The query is directed to the home subscriber server and is based on a first registration request for the user. The first registration request is received from a proxy call session control function. E.g., the second registration request may be the forwarded first registration request, or it may be a modified first registration request.
The composing means 220 composes a first response to the first registration request (S220). If the second response is not received from the home subscriber server (i.e. HSS is not available), the first response comprises an indication that the home subscriber server is not available.
The providing means 230 provides the first response to the proxy call session control function in response to the first registration request (S230). Fig. 13 shows an apparatus according to an embodiment of the invention.
The apparatus comprises at least one processor 310 and at least one memory 320 including computer program code. The at least one processor 310, with the at least one memory 320 and the computer program code, is arranged to cause the apparatus to at least perform any of the methods of Figs. 8, 10, and 12. Embodiments of the invention may be employed in IMS, e.g. of a 3GPP network of any generation (3G, 4G, 5G,...). They may be employed also in other networks with corresponding functions of call session control functions like CDMA, EDGE, UMTS, LTE, LTE-A, WiFi networks, etc.. A terminal (device) or a user equipment may be a mobile phone, a smart phone, a PDA, a laptop or any other terminal which may be attached to the respective network.
In addition or instead of expiration of a registration at a predefined time after the registration, in some embodiments a registration may expire after some time without activity in the session.
The provided/received information may comprise one or more pieces of information related to different meanings. One information may be transmitted in one or plural messages.
Names of network elements, protocols, and methods are based on current standards. In other versions or other technologies, the names of these network elements and/or protocols and/or methods may be different, as long as they provide a corresponding functionality. If not otherwise stated or otherwise made clear from the context, the statement that two entities are different means that they perform different functions. It does not necessarily mean that they are based on different hardware. That is, each of the entities described in the present description may be based on a different hardware, or some or all of the entities may be based on the same hardware.
According to the above description, it should thus be apparent that exemplary embodiments of the present invention provide, for example a call session control function, or a component thereof, an apparatus embodying the same, a method for controlling and/or operating the same, and computer program(s) controlling and/or operating the same as well as mediums carrying such computer program(s) and forming computer program product(s).
Implementations of any of the above described blocks, apparatuses, systems, techniques or methods include, as non limiting examples, implementations as hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof. It is to be understood that what is described above is what is presently considered the preferred embodiments of the present invention. However, it should be noted that the description of the preferred embodiments is given by way of example only and that various modifications may be made without departing from the scope of the invention as defined by the appended claims.

Claims

Claims:
1. Apparatus, comprising
checking means adapted to check if, in response to an issued second registration request for a user, an indication is received that a home subscriber server is not available, wherein the second registration request is based on a received first registration request for the user;
retrieving means adapted to retrieve an address of a serving call session control function from a data repository different from the home subscriber server if the indication is received that the home subscriber server is not available, wherein, according to the data repository, the user is registered with the serving call session control function;
issuing means adapted to issue a third registration request for the user to the serving call session control function, wherein the third registration request is based on the first registration request.
2. Apparatus according to claim 1 , further comprising
adding means adapted to add a limiting information to the third registration request, wherein the limiting information indicates that the address of the serving call session control function is not provided by the home subscriber server,
wherein the issuing means is further adapted to issue the third registration request with the limiting information added.
3. Apparatus according to any of claims 1 and 2, comprising the data repository.
4. Apparatus according to any of claims 1 to 3, further comprising
obtaining means adapted to obtain, from an earlier response to a forwarded earlier registration request for the user, the address of the serving call session control function, wherein the earlier response was received earlier than the first registration request; and
storing means adapted to store a data pair comprising an identification of the user and the address of the serving call session control function in the data repository.
5. Apparatus, comprising
monitoring means adapted to monitor if a registration request for a user comprising a limiting information is received from a proxy call session control function, wherein the limiting information indicates that the address of the apparatus used for the registration request is not provided by a home subscriber server;
extending means adapted to extend a service control for the user if the registration request is received.
6. The apparatus according to claim 5, wherein
the monitoring means is adapted to monitor if the registration request for the terminal device is received only when the service control is about to expire.
7. The apparatus according to any of claims 5 and 6, wherein
the extending means is adapted to extend the service control for one or more first services, wherein the home subscriber server may be not available for successful execution of each of the one or more first services.
8. The apparatus according to any of claims 5 to 7, further comprising
terminating means adapted to terminate the service control for one or more second services, wherein the home subscriber server has to be available for successful execution of each of the second services.
9. The apparatus according to any of claims 5 to 8, further comprising
checking means adapted to check if the apparatus performs the service control for the user;
preventing means adapted to prevent the extending means from extending the service control for the user if the apparatus does not perform the service control for the user when the registration request is received.
10. Apparatus, comprising
evaluating means adapted to evaluate whether a second response to a query for a serving call session control function for a user is received from a home subscriber server, wherein the query is based on a first registration request for the user received from a proxy call session control function;
composing means adapted to compose a first response to the first registration request, wherein, if the second response is not received from the home subscriber server, the first response comprises an indication that the home subscriber server is not available; providing means adapted to provide the first response to the proxy call session control function in response to the first registration request.
1 1. Apparatus according to any of claims 1 to 10, wherein the apparatus is a call session control function of an internet protocol multimedia subsystem.
12. The apparatus according to claim 1 1 , wherein the internet protocol multimedia subsystem belongs to a communication network according to a third generation partnership project.
13. Method, comprising
checking if, in response to an issued second registration request for a user, an indication is received that a home subscriber server is not available, wherein the second registration request is based on a received first registration request for the user;
retrieving an address of a serving call session control function from a data repository different from the home subscriber server if the indication is received that the home subscriber server is not available, wherein, according to the data repository, the user is registered with the serving call session control function;
issuing a third registration request for the user to the serving call session control function, wherein the third registration request is based on the first registration request.
14. Method according to claim 13, further comprising
adding a limiting information to the third registration request, wherein the limiting information indicates that the address of the serving call session control function is not provided by the home subscriber server,
wherein the issuing is further adapted to issue the third registration request with the limiting information added.
15. Method according to any of claims 13 and 14, wherein an apparatus performing the method comprises the data repository.
16. Method according to any of claims 13 to 15, further comprising
obtaining, from an earlier response to a forwarded earlier registration request for the user, the address of the serving call session control function, wherein the earlier response was received earlier than the first registration request; and storing a data pair comprising an identification of the user and the address of the serving call session control function in the data repository.
17. Method, comprising
monitoring if a registration request for a user comprising a limiting information is received from a proxy call session control function, wherein the limiting information indicates that the address of an apparatus performing the method used for the registration request is not provided by a home subscriber server;
extending a service control for the user if the registration request is received.
18. The method according to claim 17, wherein
the monitoring if the registration request for the terminal device is received is performed only when the service control is about to expire.
19. The method according to any of claims 17 and 18, wherein
the extending is adapted to extend the service control for one or more first services, wherein the home subscriber server may be not available for successful execution of each of the one or more first services.
20. The method according to any of claims 17 to 19, further comprising
terminating the service control for one or more second services, wherein the home subscriber server has to be available for successful execution of each of the second services.
21. The method according to any of claims 17 to 20, further comprising
checking if the apparatus performs the service control for the user;
preventing the extending the service control for the user if the apparatus does not perform the service control for the user when the registration request is received.
22. Method, comprising
evaluating whether a second response to a query for a serving call session control function for a user is received from a home subscriber server, wherein the query is based on a first registration request for the user received from a proxy call session control function; composing a first response to the first registration request, wherein, if the second response is not received from the home subscriber server, the first response comprises an indication that the home subscriber server is not available;
providing the first response to the proxy call session control function in response to the first registration request.
23. A computer program product comprising a set of instructions which, when executed on an apparatus, is configured to cause the apparatus to carry out the method according to any one of method claims 13 to 22.
24. The computer program product according to claim 23, embodied as a computer-readable medium or directly loadable into a computer.
PCT/EP2013/064994 2013-07-16 2013-07-16 Re-registration in case of hss outage WO2015007310A1 (en)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016132183A1 (en) * 2015-02-20 2016-08-25 Telefonaktiebolaget Lm Ericsson (Publ) Nodes and methods for bypassing a network node in an internet protocol (ip) multimedia subsystem (ims) system
CN112714442A (en) * 2019-10-24 2021-04-27 中国移动通信集团山东有限公司 Exception handling method and device, storage medium and server
CN112997461A (en) * 2018-11-09 2021-06-18 诺基亚技术有限公司 Method, apparatus and computer program
WO2023109967A1 (en) * 2021-12-16 2023-06-22 中兴通讯股份有限公司 Request processing method, network node and computer-readable storage medium
EP4123984A4 (en) * 2020-04-22 2024-04-03 Zte Corp Associated service registration method, related device and computer-readable storage medium

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080227451A1 (en) * 2007-03-16 2008-09-18 Keiji Fukui Home subscriber server configuration method and system
WO2008154955A1 (en) * 2007-06-19 2008-12-24 Telefonaktiebolaget Lm Ericsson (Publ) Ims recovery after hss failure
US20120290871A1 (en) * 2009-11-27 2012-11-15 France Telecom Method of changing over from a primary hss to a backup hss in an ip network

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080227451A1 (en) * 2007-03-16 2008-09-18 Keiji Fukui Home subscriber server configuration method and system
WO2008154955A1 (en) * 2007-06-19 2008-12-24 Telefonaktiebolaget Lm Ericsson (Publ) Ims recovery after hss failure
US20120290871A1 (en) * 2009-11-27 2012-11-15 France Telecom Method of changing over from a primary hss to a backup hss in an ip network

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016132183A1 (en) * 2015-02-20 2016-08-25 Telefonaktiebolaget Lm Ericsson (Publ) Nodes and methods for bypassing a network node in an internet protocol (ip) multimedia subsystem (ims) system
US9749981B2 (en) 2015-02-20 2017-08-29 Telefonaktiebolaget Lm Ericsson (Publ) IMS system and method for transmitting a reregister request to an S-CSCF
CN112997461A (en) * 2018-11-09 2021-06-18 诺基亚技术有限公司 Method, apparatus and computer program
CN112997461B (en) * 2018-11-09 2023-05-30 诺基亚技术有限公司 Method, apparatus and computer program
US11690040B2 (en) 2018-11-09 2023-06-27 Nokia Technologies Oy Method, apparatus and computer program
CN112714442A (en) * 2019-10-24 2021-04-27 中国移动通信集团山东有限公司 Exception handling method and device, storage medium and server
CN112714442B (en) * 2019-10-24 2023-04-18 中国移动通信集团山东有限公司 Exception handling method and device, storage medium and server
EP4123984A4 (en) * 2020-04-22 2024-04-03 Zte Corp Associated service registration method, related device and computer-readable storage medium
WO2023109967A1 (en) * 2021-12-16 2023-06-22 中兴通讯股份有限公司 Request processing method, network node and computer-readable storage medium

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