WO2021012266A1

WO2021012266A1 - Method and apparatus for subscriber migration

Info

Publication number: WO2021012266A1
Application number: PCT/CN2019/097714
Authority: WO
Inventors: Debashish PATTNAIK; Erqun SUN
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ); Debashish PATTNAIK
Priority date: 2019-07-25
Filing date: 2019-07-25
Publication date: 2021-01-28

Abstract

Various embodiments of the present disclosure provide a method for subscriber migration push based from one P-CSCF to another P-CSCF. The method which may be performed by a first server comprises sending a first request message to a second server when a subscriber migration criterion is met, wherein the first request message transmits subscriber migration information from the first server to the second server. The method further comprises sending a second request message to a terminal device, wherein the second request message indicates that a subscriber associated with the terminal device is migrated from the first server to the second server. According to the embodiments of the present disclosure, the subscriber migration push based from one P-CSCF to another P-CSCF automatically can be supported to reduce impact the ongoing session.

Description

METHOD AND APPARATUS FOR SUBSCRIBER MIGRATION

FIELD OF THE INVENTION

The present disclosure generally relates to communication networks, and more specifically, to subscriber migration of push based in a communication network.

BACKGROUND

This section introduces aspects that may facilitate a better understanding of the disclosure. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.

Communication service providers and network operators have been continually facing challenges to deliver value and convenience to consumers by, for example, providing compelling network services and performance. With the rapid development of networking and communication technologies, wireless communication networks such as long-term evolution (LTE) /fourth generation (4G) network and new radio (NR) /fifth generation (5G) network are expected to achieve high traffic capacity and end-user data rate with lower latency. To meet the diverse requirements of new services across a wide variety of industries, the 3rd generation partnership project (3GPP) is developing a core network architecture such as evolved packet core (EPC) or 5G core (5GC) , which is supposed to support the wide range of performance requirements demanded by new business opportunities, multiple access technologies, a variety of services and new device types.

The Internet Protocol (IP) Multimedia Subsystem (IMS) is an architectural framework for delivering IP multimedia services. Call Session Control Function (CSCF) processes Session Initial Protocol (SIP) signaling packets in the IMS and consists of several types of SIP servers. One of the most common SIP servers in the CSCF is Proxy-CSCF (P-CSCF) which is the first point of contact for device and controls authentication.

SUMMARY

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

A terminal device is registered through a P-CSCF to an IMS network. When traffic reaches the handling capacity maximum threshold of the P-CSCF or the P-CSCF needs to block handling further traffic during a local maintenance period, subscriber (s) associated with the P-CSCF may need to be immigrated to another P-CSCF. Currently, the subscriber immigration from a current P-CSCF (P-CSCF-Current) to a new P-CSCF (P-CSCF-New) may require manual intervention and/or manual steps which may introduce an increase of network downtime, and the manual procedures may be error prone. Hence it may be desirable to improve the method of subscriber immigration from the P-CSCF-Current to the P-CSCF-New.

Various embodiments of the present disclosure propose a solution of subscriber migration from the P-CSCF-Current to the P-CSCF-New automatically based on push notification when the subscriber migration criteria is met, for example, the traffic reaches configured maximum threshold capacity or it is during local maintenance period. The method may not need manual intervention for network maintenance operations, so that it might reduce or have no downtime/network disturbance.

According to a first aspect of the present disclosure, there is provided a method performed by a first server. The method comprises sending a first request message to a second server when a subscriber migration criterion is met, wherein the first request message transmits subscriber migration information from the first server to the second server. The method further comprises sending a second request message to a terminal device, wherein the second request message indicates that a subscriber associated with the terminal device is migrated from the first server to the second server. Wherein the first server may comprise current Proxy Call State Control Function, P-CSCF, via which a subscriber associated with a terminal device has been already registered with a network server which may comprise a Service Capability Server/Application Server, SCS/AS, or Application Function, AF; the second server may comprise a new P-CSCF, and the subscriber associated with the terminal device is migrated from the P-CSCF-Current to P-CSCF-New.

In accordance with an exemplary embodiment, the first request message may comprise a Session Initiation Protocol, SIP, message.

In accordance with an exemplary embodiment, the subscriber migration information may comprise at least one of: terminal device contact information; session binding records between a network server and the terminal device; minimum of registration times; and maximum of registration times.

In accordance with an exemplary embodiment, the second request message may comprise a Push Notification Request, PNR, with push notification information. The push notification information may comprise at least one of a destination address of the second server; a timer indicating allowable time for the subscriber associated with the terminal device to register with the network server. The destination address may comprise an IP address.

In accordance with an exemplary embodiment, the method according to the first aspect of the present disclosure may further comprise sending the second request message to the terminal device via a push notification service server.

In accordance with an exemplary embodiment, the method according to the first aspect of the present disclosure may further comprise: prior to sending the first request message and the second request message, receiving a new session request from the terminal device wherein the new session request indicates that the terminal device registers the network server via the first server;

In accordance with an exemplary embodiment, the method according to the first aspect of the present disclosure may further comprise: wherein the terminal device is registered with a network server via the first server, receiving a de-register message by the first server and from the network server, wherein the de-register message may indicate unbinding of the terminal device from the first server.

In accordance with an exemplary embodiment, the subscriber migration criterion may comprise at least one of: reaching a traffic handling capacity maximum threshold of the first server; and blocking handling further traffic during a local maintenance period.

In accordance with an exemplary embodiment, the method according to the first aspect of the present disclosure may further comprise: the terminal device performing as a push client.

According to a second aspect of the present disclosure, there is provided an apparatus. The apparatus may comprise one or more processors and one or more memories comprising computer program codes. The one or more memories and the computer program codes may be configured to, with the one or more processors, cause the apparatus at least to perform any step of the method according to the first aspect of the present disclosure.

According to a third aspect of the present disclosure, there is provided a computer-readable medium having computer program codes embodied thereon which, when executed on a computer, cause the computer to perform any step of the method according to the first aspect of the present disclosure.

According to a fourth aspect of the present disclosure, there is provided an apparatus. The apparatus comprises a sending unit. In accordance with some exemplary embodiments, the sending unit may be operable to carry out at least the sending step of the method according to the first aspect of the present disclosure.

According to a fifth aspect of the present disclosure, there is provided a method performed by a terminal device. The method comprises receiving a second request message from a first server, wherein the second request message indicates that a subscriber associated with the terminal device is migrated from the first server to a second server. The method further comprises sending a register message to the second server, wherein the register message indicates that the subscriber associated with the terminal device registers with the network server via the second server. Wherein the first server may comprise P-CSCF-Current, via which a subscriber associated with a terminal device has been already registered with a network server (e.g., a SCS/AS or an AF etc. ) ; the second server may comprise a P-CSCF-New, and the subscriber associated with the terminal device is migrated from the P-CSCF-Current to P-CSCF-New.

In accordance with an exemplary embodiment, the second request message may comprise a Push Notification Request, PNR, with the push notification information.

In accordance with an exemplary embodiment, the push notification information may comprise at least one of: a destination address of the second server; and a timer indicating allowable time for the subscriber associated with the terminal device to register with the network server.

In accordance with an exemplary embodiment, the method according to the fifth aspect of the present disclosure may further comprise receiving the second request message from the first server via a push notification service server.

In accordance with an exemplary embodiment, the method according to the fifth aspect of the present disclosure may further comprise sending the register message during the allowable time identified by the timer in the second request message. The method may further comprise sending the register message to the second server with the destination address identified in the second request message.

In accordance with an exemplary embodiment, the destination address may comprise an Internet Protocol, IP, address.

In accordance with an exemplary embodiment, the method according to the fifth aspect of the present disclosure may further comprise, prior to sending the register message, sending a transport connection initiative message to the second server, wherein the transport connection initiative message indicates to establish transport connection between the terminal device and the second server.

In accordance with an exemplary embodiment, the transport connection may comprise Transport Control Protocol, TCP, connection or User Datagram Protocol, UDP connection.

In accordance with an exemplary embodiment, the method according to the fifth aspect of the present disclosure may further comprise, prior to receiving the second request message, sending a new session request to the first server wherein the new session request indicates that the terminal device registers the network server via the first server.

In accordance with an exemplary embodiment, the method according to the fifth aspect of the present disclosure may further comprise: the terminal device performing as a push client.

According to a sixth aspect of the present disclosure, there is provided an apparatus. The apparatus may comprise one or more processors and one or more memories comprising computer program codes. The one or more memories and the computer program codes may be configured to, with the one or more processors, cause the apparatus at least to perform any step of the method according to the fifth aspect of the present disclosure.

According to a seventh aspect of the present disclosure, there is provided a computer-readable medium having computer program codes embodied thereon which, when executed on a computer, cause the computer to perform any step of the method according to the fifth aspect of the present disclosure.

According to an eighth aspect of the present disclosure, there is provided an apparatus. The apparatus comprises a receiving unit and a sending unit. In accordance with some exemplary embodiments, the receiving unit may be operable to carry out at least the receiving step of the method according to the fifth aspect of the present disclosure. The sending unit may be operable to carry out at least the sending step of the method according to the fifth aspect of the present disclosure.

According to a ninth aspect of the present disclosure, there is provided a method performed by a second server. The method comprises receiving a first request message from a first server, wherein the first request message transmits subscriber migration information from the first server to the second server. The method further comprises receiving a register message from a terminal device wherein the register message indicates that the subscriber associated with the terminal device registers with the network server via the second server. The method another further comprises sending a register message to a network server, wherein the register message indicates a subscriber associated with the terminal device registers with the network server. Wherein the first server may comprise a P-CSCF-Current, via which a subscriber associated with a terminal device has been already registered with a network server (e.g., a SCS/AS or an AF etc. ) ; the second server may comprise a P-CSCF-New, and the subscriber associated with the terminal device is migrated from the P-CSCF-Current to the P-CSCF-New.

In accordance with an exemplary embodiment, the subscriber migration information may comprise at least one of: terminal device contact information; and session binding records between a network server and the terminal device; and minimum of registration times; and maximum of registration times.

In accordance with an exemplary embodiment, the method according to the ninth aspect of the present disclosure may further comprise prior to receiving the register message, receiving a transport connection initiative message from the terminal device, wherein the transport connection initiative message indicates establishing transport connection between the terminal device and the second server.

In accordance with an exemplary embodiment, the method according to the ninth aspect of the present disclosure may further comprise: the terminal device performing as a push client.

According to a tenth aspect of the present disclosure, there is provided an apparatus. The apparatus may comprise one or more processors and one or more memories comprising computer program codes. The one or more memories and the computer program codes may be configured to, with the one or more processors, cause the apparatus at least to perform any step of the method according to the ninth aspect of the present disclosure.

According to an eleventh aspect of the present disclosure, there is provided a computer-readable medium having computer program codes embodied thereon which, when executed on a computer, cause the computer to perform any step of the method according to the ninth aspect of the present disclosure.

According to a twelfth aspect of the present disclosure, there is provided an apparatus. The apparatus comprises a receiving unit and a sending unit. In accordance with some exemplary embodiments, the receiving unit may be operable to carry out at least the receiving step of the method according to the ninth aspect of the present disclosure. The sending unit may be operable to carry out at least the sending step of the method according to the ninth aspect of the present disclosure.

According to a thirteenth aspect of the present disclosure, there is provided a method performed by a second server which may comprise a SCS/AS or an AF. The method comprises receiving a first request message from a first server, wherein the first request message transmits subscriber migration information from the first server to the second server. The method further comprises receiving a register message from a terminal device wherein the register message indicates that the subscriber associated with the terminal device registers with the network server via the second server. The method another further comprises sending a register message to a network server, wherein the register message indicates a subscriber associated with the terminal device registers with the network server. Wherein the first server may comprise a P-CSCF-Current, via which a subscriber associated with a terminal device has been already registered with a network server; the second server may comprise a P-CSCF-New, and the subscriber associated with the terminal device is migrated from the P-CSCF-Current to the P-CSCF-New.

In accordance with an exemplary embodiment, the method according to the thirteenth aspect of the present disclosure may further comprise, prior to receiving the register message, receiving a transport connection initiative message from the terminal device, wherein the transport connection initiative message indicates establishing transport connection between the terminal device and the second server.

In accordance with an exemplary embodiment, the method according to the thirteenth aspect of the present disclosure may further comprise: the terminal device performing as a push client.

According to a fourteenth aspect of the present disclosure, there is provided an apparatus. The apparatus may comprise one or more processors and one or more memories comprising computer program codes. The one or more memories and the computer program codes may be configured to, with the one or more processors, cause the apparatus at least to perform any step of the method according to the thirteenth aspect of the present disclosure.

According to a fifteenth aspect of the present disclosure, there is provided a computer-readable medium having computer program codes embodied thereon which, when executed on a computer, cause the computer to perform any step of the method according to the thirteenth aspect of the present disclosure.

According to a sixteenth aspect of the present disclosure, there is provided an apparatus. The apparatus comprises a receiving unit, updating unit and a sending unit. In accordance with some exemplary embodiments, the receiving unit may be operable to carry out at least the receiving step of the method according to the thirteenth aspect of the present disclosure. The updating unit may be operable to carry out at least the updating step of the m. ethod according to the thirteenth aspect of the present disclosure. The receiving unit may be operable to carry out at least the receiving step of the method according to the thirteenth aspect of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure itself, the preferable mode of use and further objectives are best understood by reference to the following detailed description of the embodiments when read in conjunction with the accompanying drawings, in which:

Fig. 1 is a diagram illustrating an exemplary procedure for subscriber migration push based initiated by P-CSCF according to some embodiments of the present disclosure;

Fig. 2 is a diagram illustrating an exemplary procedure for subscriber migration push based when P-CSCF receives incoming session before migration from a Push Client according to some embodiments of the present disclosure;

Fig. 3 is a flowchart illustrating a method according to some embodiments of the present disclosure;

Fig. 4 is a flowchart illustrating another method according to some embodiments of the present disclosure;

Fig. 5 is a flowchart illustrating yet another method according to some embodiments of the present disclosure;

Fig. 6 is a flowchart illustrating a further method according to some embodiments of the present disclosure;

Fig. 7 is a block diagram illustrating an apparatus according to some embodiments of the present disclosure;

Fig. 8 is a block diagram illustrating another apparatus according to some embodiments of the present disclosure;

Fig. 9 is a block diagram illustrating yet another apparatus according to some embodiments of the present disclosure;

Fig. 10 is a block diagram illustrating yet another apparatus according to some embodiments of the present disclosure; and

Fig. 11 is a block diagram illustrating a further apparatus according to some embodiments of the present disclosure.

DETAILED DESCRIPTION

The embodiments of the present disclosure are described in detail with reference to the accompanying drawings. It should be understood that these embodiments are discussed only for the purpose of enabling those skilled persons in the art to better understand and thus implement the present disclosure, rather than suggesting any limitations on the scope of the present disclosure. Reference throughout this specification to features, advantages, or similar language does not imply that all of the features and advantages that may be realized with the present disclosure should be or are in any single embodiment of the disclosure. Rather, language referring to the features and advantages is understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present disclosure. Furthermore, the described features, advantages, and characteristics of the disclosure may be combined in any suitable manner in one or more embodiments. One skilled in the relevant art will recognize that the disclosure may be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of the disclosure.

As used herein, the term “communication network” refers to a network following any suitable communication standards, such as new radio (NR) , long term evolution (LTE) , LTE-Advanced, wideband code division multiple access (WCDMA) , high-speed packet access (HSPA) , and so on. Furthermore, the communications between a terminal device and a network node in the communication network may be performed according to any suitable generation communication protocols, including, but not limited to, the first generation (1G) , the second generation (2G) , 2.5G, 2.75G, the third generation (3G) , 4G, 4.5G, 5G communication protocols, and/or any other protocols either currently known or to be developed in the future. As used herein, the term “terminal device” may be any device intended for accessing services via an access network and configured to communicate over the access network. For instance, the terminal device may be, but is not limited to: mobile phone, smart phone, sensor device, meter, vehicle, household appliance, medical appliance, media player, camera, or any type of consumer electronic, for instance, but not limited to, television, radio, lighting arrangement, tablet computer, laptop, or PC. The terminal device may be a portable, pocket-storable, hand-held, computer-comprised, or vehicle-mounted mobile device, enabled to communicate voice and/or data, via a wireless or wireline connection.

As used herein, the terms “first” , “second” and so forth refer to different elements. The singular forms “a” and “an” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises” , “comprising” , “has” , “having” , “includes” and/or “including” as used herein, specify the presence of stated features, elements, and/or components and the like, but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof. The term “based on” is to be read as “based at least in part on” . The term “one embodiment” and “an embodiment” are to be read as “at least one embodiment” . The term “another embodiment” is to be read as “at least one other embodiment” . Other definitions, explicit and implicit, may be included below.

IP Multimedia Subsystem (IMS) which is one of the most complex Network Function Virtualization (NFV) instances. Proxy-CSCF (P-CSCF) is the first point of contact for device to access the IMS network and controls authentication. When the current P-CSCF (P-CSCF-Current) reaches the maximum allowed threshold of traffic or during the planned maintenance for the P-CSCF-Current, a subscriber associated with a terminal device which have already registered with a network server (e.g., a SCS/AS, an AS) via the P-CSCF-Current may need to migrate to other new P-CSCF (P-CSCF-New) . As described above, the existing migration procedure may require manual intervention and/or manual steps which introduces an increase of network downtime, and the manual procedure may be error prone. Hence the automatic subscriber migration from the P-CSCF-Current to the P-CSCF-New might be admired and which might be no impact on the ongoing session/traffic.

Fig. 1 is a diagram illustrating an exemplary procedure for subscriber migration push based initiated by a P-CSCF-Current from the P-CSCF-Current to a P-CSCF-New. The subscriber associated with a terminal device has already registered with a network server (e.g., a SCS/AS or an AF) via the P-CSCF-Current. The terminal device has indicated its support for Push notification in an initial or a previous SIP register message. The terminal device performs as a push client in the Fig. 1 and Fig. 2. In 101, when a subscriber migration requirement is met, for example, the traffic reaches the maximum of threshold of the P-CSCF-Current, or it is during the planned maintenance time of the P-CSCF-Current, the P-CSCF-Current initiates the subscriber migration push based from the P-CSCF-Current to the P-CSCF-New. A push notification, also known as a server push notification, is the delivery of information to a computing device from an application server where the request for the transaction is initiated by the server rather than by an explicit request from the client. The 3GPP has defined the push notification in the P-CSCF function which support sending push notification to a push service. The P-CSCF-Current sends 102 a push notification request to a Push Notification Service. And the P-CSCF-Current sends 103 a message to P-CSCF-New to trigger the subscribe migration procedure in the P-CSCF-New. When the Push Notification Service receives the 102 the push notification, forwards it to the Push client in 104. As depicted above, the terminal device performs as the Push Client. The push notification message includes a destination address of the P-CSCF-New and a refresh timer. The P-CSCF-New address might be IP address and the refresh timer indicates allowable time for the subscriber associated with the terminal device to register with the network server. The push client 105 initiates a fresh registration session towards P-CSCF-New after receives the push notification. The Push Client 106 initiates a new transport connection towards the P-CSCF-New and gets established between the push client and the P-CSCF-New. The Push Client 107 sends a register request towards the P-CSCF-New along with push notification parameters provided by the Push Notification Service. The register request might be a SIP message. In 108, the P-CSCF-New receives the SIP REGISTER request and forwards it to the network server on the Gm interface. In 109, the network server sends a De-Register message to the P-CSCF-Current to get itself unbind from the Push Client. In 110, the network server updates the Push Client information in its nodes/database/local-buffer. In 111, the network server sends a successful response towards the P-CSCF-New indicating the subscriber migration finished successfully. In 112, the P-CSCF-New sends a 200OK response (for the SIP MESSAGE) towards the P-CSCF-Current informing the successful subscriber migration of the push client and closes a dialog that was created by the P-CSCF-Current.

Fig. 2 is a diagram illustrating an exemplary procedure for subscriber migration push based during session initiation initiated by Push Client. As depicted above in Fig. l, the subscriber associated with the terminal device has already registered with IMS network via the P-CSCF-Current. The terminal device has indicated its support for Push notification in the initial or previous SIP register message. Terminal device performs as a push client in the Fig. 1 and Fig. 2. In 200, the Push Client initiates a new session request towards the P-CSCF-Current, the following procedures 201-212 are same as the procedures 101-112 in Fig. 1. Please refer to the Fig. 1 depiction above. In 213, when P-CSCF-Current getting informed of the successful subscriber migration, P-CSCF-Current sends redirect call with the Contact information of P-CSCF-New to Push Client indicating Push Client to redirect to P-CSCF-New by responding with a SIP message. In 214, the Push Client sends the redirected session request to the P-CSCF-New and the subscriber migration initiated during session initiation initiated by Push Client finished successfully.

Fig. 3 is a flowchart illustrating a method 300 according to some embodiments of the present disclosure. The method 300 illustrated in Fig. 3 may be performed by a first network node or an apparatus communicatively coupled to the first network node. In accordance with an exemplary embodiment, the first network node may comprise a network node with P-CSCF-Current. Optionally, the first network node may be implemented as a P-CSCF-Current or any other suitable network function or entity which may be able to perform the P-CSCF-Current functionalities.

According to the exemplary method 300 illustrated in Fig. 3, when the first network node detects the subscriber migration criterion is met, (e.g. reaching a traffic handling capacity maximum threshold of the first server; or blocking handling further traffic during a local maintenance period. ) , the first network node may send a first message towards the second network node as shown in block 302. And the first network node may send a second message towards a terminal device via a Push Notification service, as shown in block 304. In accordance with some exemplary embodiments, the first network node may comprise a P-CSCF-Current, via which the subscriber associated with the terminal device has been already registered with the network server. According to an exemplary embodiment the terminal device may comprises a Push Client. According to an exemplary embodiment, the message towards the terminal device may comprise a Push notification request as described with respect to Fig. 1 and Fig. 2. In accordance with some exemplary embodiments, the second network node may comprise a P-CSCF-New, and the subscriber associated with the terminal device is migrated from the P-CSCF-Current to the P-CSCF-New. According to an exemplary embodiment, the first network node may receive a De-Register and unbinding Push Client message from the network sever indicating P-CSCF-Current de-register and unbinding with the subscriber which has migrated to P-CSCF-New.

According to an exemplary embodiment, the first network node may receive a message from the second network node indicating the subscriber migration finished successfully. According to an exemplary embodiment, the first network node may receive a new session request message from the terminal device to initiate a new session in P-CSCF-Current as described with respect to Fig. 2. After receives the message, if P-CSCF-Current detects the criterion is met, the subscriber migration is triggered as described above. The new coming session would be redirected to P-CSCF-New which would be described in Fig. 4. In accordance with some exemplary embodiments, the first network node may receive a message indicating that the new coming session has been redirected to P-CSCF-New successfully and P-CSCF-Current forward the message towards the terminal device as described with respect to Fig. 2.

Fig. 4 is a flowchart illustrating a method 400 according to some embodiments of the present disclosure. The method 400 illustrated in Fig. 4 may be performed by a terminal device. In accordance with an exemplary embodiment, the terminal device performs as a Push Client. The terminal device may comprise a User Equipment (UE) .

According to the exemplary method 400 illustrated in Fig. 4, a terminal device may receive a second request message from a first server as shown in block 402. According to an exemplary embodiment, the second request message may be Push Notification Request with a P-CSCF-New address and refresh timer. And according to an exemplary embodiment, the second request message may be received from the first network node via a Push Notification service. The message indicates that a subscriber associated with the terminal device is migrated from the first server to a second server.

According to an exemplary embodiment, the terminal device may send a register message to a second network node as shown in block 404. The register message may be a SIP register message including Push notification information. In accordance with an exemplary embodiment, the terminal device may send a transport connection initiative message towards the second network node. The transport connection initiative message indicates establishing transport connection between the terminal device and the second server.

According to an exemplary embodiment, for example, the subscriber migration is during session initiation and the subscriber migration is initiated by terminal device, prior to receiving the second request message, the terminal device may send a new session request to the first server wherein the new session request indicating that the terminal device registers the network server via the first server. After the subscriber migration has finished successfully from the P-CSCF-Current to the P-CSCF-New, the terminal device may receive a 302 Redirect Call message from the P-CSCF-New, then the terminal device may send Redirected Call/Session request to the P-CSCF-New as described with respect to Fig. 2.

Fig. 5 is a flowchart illustrating a method 400 according to some embodiments of the present disclosure. The method 500 illustrated in Fig. 5 may be performed by a second network node or an apparatus communicatively coupled to the first network node. In accordance with an exemplary embodiment, the second network node may comprise a network node with P-CSCF-New. The P-CSCF-New might be a P-CSCF and the subscriber associated with the terminal device is migrated from the P-CSCF-Current to the P-CSCF. Optionally, the second network node may be implemented as a P-CSCF-New or any other suitable network function or entity which may be able to perform the P-CSCF-New functionalities.

According to the exemplary method 500 illustrated in Fig. 5, when the second network node receive a first message from the first network node as shown in block 502. In accordance with some exemplary embodiments, the second network node may comprise a P-CSCF-New, and the first network node may comprise a P-CSCF-Current. According to an exemplary embodiment, the first request message may be a SIP message with the subscriber migration information. The subscriber migration information may be at least one of: terminal device contact information, session binding records between a network server and the terminal device, minimum of registration times, and maximum of registration times.

According to an exemplary embodiment, the second network node may receive a register message from a terminal device as shown in block 502. In accordance with some exemplary embodiments, the terminal device may comprise a Push Client. The register message may be a SIP register message including Push notification information. Optionally, the second network node may receive a transport connection initiative message from the terminal device. The transport connection initiative message indicates establishing transport connection between the terminal device and the second server. The second network node may send the register message to the network server to enable subscriber associated the terminal device registers with the network server via the P-CSCF-New as shown in block 504. The second network node may receive successful register of Push Client from the network server indicating that the terminal device registers with the network server via P-CSCF-New successfully. And the P-CSCF-New may forward the message to the P-CSCF-Current thorough a 200OK for message as described with respect to Fig. 1 and Fig. 2.

According to an exemplary embodiment, when it is the subscriber migration initiated by the terminal device (e.g., a Push Client) , the second network node may receive a redirected call/session request after the subscriber migration finished successfully.

Fig. 6 is a flowchart illustrating a method 600 according to some embodiments of the present disclosure. The method 600 illustrated in Fig. 6 may be performed by a network server (e.g., a SCS/AS or an AF. ) . According to the exemplary method 600 illustrated in Fig. 6, the network server may receive a register message from a second server indicating the subscriber registration with the network server as shown in block 602. According to an exemplary embodiment, the register message may be a SIP message. And according to an exemplary embodiment, the network server may update a terminal device information in the network server after receives the register message as shown in block 604. According to an exemplary embodiment, the network server may send a de-register and unbinding Push Client message to a first server indicating enabling the P-CSCF-Current de-register and unbind with the terminal device as shown in block 606.

The proposed solution according to one or more exemplary embodiments can enable the subscriber migration push based automatically, it may avoid impact the ongoing session.

The various blocks shown in Figs. 3-6 may be viewed as method steps, and/or as operations that result from operation of computer program code, and/or as a plurality of coupled logic circuit elements constructed to carry out the associated function (s) . The schematic flow chart diagrams described above are generally set forth as logical flow chart diagrams. As such, the depicted order and labeled steps are indicative of specific embodiments of the presented methods. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more steps, or portions thereof, of the illustrated methods. Additionally, the order in which a particular method occurs may or may not strictly adhere to the order of the corresponding steps shown.

Fig. 7 is a block diagram illustrating an apparatus 700 according to various embodiments of the present disclosure. As shown in Fig. 7, the apparatus 700 may comprise one or more processors such as processor 701 and one or more memories such as memory 702 storing computer program codes 703. The memory 702 may be non-transitory machine/processor/computer readable storage medium. In accordance with some exemplary embodiments, the apparatus 700 may be implemented as an integrated circuit chip or module that can be plugged or installed into a first network node as described with respect to Fig. 3, a terminal device as described with respect to Fig. 4, a second network node as described with respect to Fig. 5, and an network server as described with respect to Fig. 6.

In some implementations, the one or more memories 702 and the computer program codes 703 may be configured to, with the one or more processors 701, cause the apparatus 700 at least to perform any operation of the method as described in connection with Fig. 3. In some implementations, the one or more memories 702 and the computer program codes 703 may be configured to, with the one or more processors 701, cause the apparatus 700 at least to perform any operation of the method as described in connection with Fig. 4. In some implementations, the one or more memories 702 and the computer program codes 703 may be configured to, with the one or more processors 701, cause the apparatus 700 at least to perform any operation of the method as described in connection with Fig. 5. In some implementations, the one or more memories 702 and the computer program codes 703 may be configured to, with the one or more processors 701, cause the apparatus 700 at least to perform any operation of the method as described in connection with Fig. 6.

Alternatively or additionally, the one or more memories 702 and the computer program codes 703 may be configured to, with the one or more processors 701, cause the apparatus 700 at least to perform more or less operations to implement the proposed methods according to the exemplary embodiments of the present disclosure.

Fig. 8 is a block diagram illustrating an apparatus 800 according to some embodiments of the present disclosure. The apparatus 800 may be implemented as a first network node or as a part of the first network node. As shown in Fig. 8, the apparatus 800 may comprise a sending unit 801. In an exemplary embodiment, the apparatus 800 may be implemented in a first network node such as a P-CSCF-Current. The sending unit 801 may be operable to carry out the operation in block 302. Optionally, the receiving unit 801 may be operable to carry out more or less operations to implement the proposed methods according to the exemplary embodiments of the present disclosure.

Fig. 9 is a block diagram illustrating an apparatus 900 according to some embodiments of the present disclosure. The apparatus 900 may be implemented as a second network node or as a part of the second network node. As shown in Fig. 9, the apparatus 900 may comprise a sending unit 901 and a receiving unit 902. In an exemplary embodiment, the apparatus 900 may be implemented in a terminal device such as a UE, may performs as a Push Client. The receiving unit 901 may be operable to carry out the operation in block 402, and the sending unit 902 may be operable to carry out the optional operation in block 404. Optionally, the receiving unit 901 and/or the sending unit 902 may be operable to carry out more or less operations to implement the proposed methods according to the exemplary embodiments of the present disclosure.

Fig. 10 is a block diagram illustrating an apparatus 1000 according to some embodiments of the present disclosure. The apparatus 1000 may be implemented as a second network node or as a part of the second network node. As shown in Fig. 10, the apparatus 1000 may comprise a receiving unit 1001 and a sending unit 1002. In an exemplary embodiment, the apparatus 1000 may be implemented in a second network node such as a P-CSCF-New. The receiving unit 1001 may be operable to carry out the operation in block 502, and the sending unit 1002 may be operable to carry out the operation in block 504. Optionally, the receiving unit 1001 and/or the obtaining unit 1002 may be operable to carry out more or less operations to implement the proposed methods according to the exemplary embodiments of the present disclosure.

Fig. 11 is a block diagram illustrating an apparatus 1100 according to some embodiments of the present disclosure. The apparatus 1100 may be implemented as a network server or as a part of the network server. As shown in Fig. 11, the apparatus 1100 may comprise a receiving unit 1101, updating unit 1102 and a sending unit 1103. In an exemplary embodiment, the apparatus 1100 may be implemented in a sever such as a SCS/AS or an AF, etc. The receiving unit 1101 may be operable to carry out the operation in block 602, the updating unit 1102 may be operable to carry out the operation in block 604, and the sending unit 1103 may be operable to carry out the operation in block 606. Optionally, the receiving unit 1101, updating unit 1102, and/or the sending unit 1103 may be operable to carry out more or less operations to implement the proposed methods according to the exemplary embodiments of the present disclosure.

In general, the various exemplary embodiments may be implemented in hardware or special purpose chips, circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the disclosure is not limited thereto. While various aspects of the exemplary embodiments of this disclosure may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

As such, it should be appreciated that at least some aspects of the exemplary embodiments of the disclosure may be practiced in various components such as integrated circuit chips and modules. It should thus be appreciated that the exemplary embodiments of this disclosure may be realized in an apparatus that is embodied as an integrated circuit, where the integrated circuit may comprise circuitry (as well as possibly firmware) for embodying at least one or more of a data processor, a digital signal processor, baseband circuitry and radio frequency circuitry that are configurable so as to operate in accordance with the exemplary embodiments of this disclosure.

It should be appreciated that at least some aspects of the exemplary embodiments of the disclosure may be embodied in computer-executable instructions, such as in one or more program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types when executed by a processor in a computer or other device. The computer executable instructions may be stored on a computer readable medium such as a hard disk, optical disk, removable storage media, solid state memory, random access memory (RAM) , etc. As will be appreciated by one of skill in the art, the function of the program modules may be combined or distributed as desired in various embodiments. In addition, the function may be embodied in whole or partly in firmware or hardware equivalents such as integrated circuits, field programmable gate arrays (FPGA) , and the like.

The present disclosure includes any novel feature or combination of features disclosed herein either explicitly or any generalization thereof. Various modifications and adaptations to the foregoing exemplary embodiments of this disclosure may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings. However, any and all modifications will still fall within the scope of the non-limiting and exemplary embodiments of this disclosure.

Claims

A method performed by a first server, comprising:

sending a first request message to a second server when a subscriber migration criterion is met, wherein the first request message transmits subscriber migration information from the first server to the second server; and

sending a second request message to a terminal device, wherein the second request message indicates that a subscriber associated with the terminal device is migrated from the first server to the second server.
The method according to claim 1, wherein the first request message comprises a Session Initiation Protocol, SIP, message.
The method according to any of claims 1-2, wherein the subscriber migration information comprises at least one of:

terminal device contact information; and

session binding records between a network server and the terminal device; and

minimum of registration times; and

maximum of registration times.
The method according to claim 3, wherein the terminal device contact information comprises an Internet Protocol, IP, address and a port.
The method according to any of claims 1-4, wherein the second request message comprises a Push Notification Request, PNR, with push notification information.
The method according to claim 5, wherein the push notification information comprises at least one of:

a destination address of the second server; and

a timer indicating allowable time for the subscriber associated with the terminal device to register with the network server.
The method according to claim 6, wherein the destination address comprises an IP address.
The method according to any of claims 1-7, further comprising:

sending the second request message to the terminal device via a push notification service server.
The method according to any of claims 1-8, further comprising:

prior to sending the first request message and the second request message,

receiving a new session request from the terminal device wherein the new session request indicates that the terminal device registers the network server via the first server;
The method according to any of claims 1-8, wherein the terminal device is registered, via the first server, with a network server, comprising receiving, by the first server and from the network server, a de-register message wherein the de-register message indicates unbinding of the terminal device from the first server.
The method according to any of claims 1-10, wherein the subscriber migration criterion comprises at least one of:

reaching a traffic handling capacity maximum threshold of the first server; and

blocking handling further traffic during a local maintenance period.
The method according to any of claims 1-11, wherein the first server comprises a current Proxy Call State Control Function, P-CSCF, via which the subscriber associated with the terminal device has been already registered with the network server.
The method according to any of claims 1-12, wherein the second server comprises a new P-CSCF, and the subscriber associated with the terminal device is migrated from the current P-CSCF to the new P-CSCF.
The method according to any of claims 1-13, wherein the network server comprises a Service Capability Server/Application Server, SCS/AS, or Application Function, AF.
The method according to any of claims 1-14, wherein the terminal device performs as a push client.
A method performed by a terminal device, comprising:

receiving a second request message from a first server, wherein the second request message indicates that a subscriber associated with the terminal device is migrated from the first server to a second server; and

sending a register message to the second server, wherein the register message indicates that the subscriber associated with the terminal device registers with the network server via the second server.
The method according to claim 16, wherein the second request message comprises a Push Notification Request, PNR, with the push notification information.
The method according to claim 17, wherein the push notification information comprises at least one of:

a destination address of the second server; and

a timer indicating allowable time for the subscriber associated with the terminal device to register with the network server.
The method according to any of claims 16-18, further comprising:

receiving the second request message from the first server via a push notification service server.
The method according to any of claims 16-19, further comprising:

sending the register message during the allowable time identified by the timer in the second request message; and

sending the register message to the second server with the destination address identified in the second request message.
The method according to claim 20, wherein the destination address comprises an Internet Protocol, IP, address.
The method according to any of claims 16-21, further comprising:

prior to sending the register message, sending a transport connection initiative message to the second server, wherein the transport connection initiative message indicates to establish transport connection between the terminal device and the second server.
The method according to claim 22, wherein the transport connection comprises Transport Control Protocol, TCP, connection or User Datagram Protocol, UDP connection.
The method according to any of claims 16-23, further comprising:

prior to receiving the second request message, sending a new session request to the first server wherein the new session request indicates that the terminal device registers the network server via the first server.
The method according to any of claims 16-24, wherein the first server comprises a current Proxy Call State Control Function, P-CSCF, via which the subscriber associated with the terminal device has been already registered with the network server.
The method according to any of claims 16-25, wherein the second server comprises a new P-CSCF, and the subscriber associated with the terminal device is migrated from the current P-CSCF to the new P-CSCF.
The method according to any of claims 16-26, wherein the network server comprises a Service Capability Server/Application Server, SCS/AS, or Application Function, AF.
The method according to any of claims 16-27, wherein the terminal device performs as push client.
A method performed by a second server, comprising:

receiving a first request message from a first server, wherein the first request message transmits subscriber migration information from the first server to the second server; and

receiving a register message from a terminal device wherein the register message indicates that the subscriber associated with the terminal device registers with the network server via the second server; and

sending a register message to a network server, wherein the register message indicates a subscriber associated with the terminal device registers with the network server.
The method according to claim 29, wherein the first request message comprises a Session Initiation Protocol, SIP, message.
The method according to any of claims 29-30, wherein the subscriber migration information comprises at least one of:

terminal device contact information; and

session binding records between a network server and the terminal device; and

minimum of registration times; and

maximum of registration times.
The method according to any of claims 29-31, further comprising:

prior to receiving the register message, receiving a transport connection initiative message from the terminal device, wherein the transport connection initiative message indicates establishing transport connection between the terminal device and the second server.
The method according to claim 32, wherein the transport connection comprises Transport Control Protocol, TCP, connection or User Datagram Protocol, UDP connection.
The method according to any of claims 29-33, wherein the first server comprises a current Proxy Call State Control Function, P-CSCF, via which the subscriber associated with the terminal device has been already registered with the network server.
The method according to any of claims 29-34, wherein the second server comprises a new P-CSCF, and the subscriber associated with the terminal device is migrated from the current P-CSCF to the new P-CSCF.
The method according to any of claims 29-35, wherein the network server comprises a Service Capability Server/Application Server, SCS/AS, or Application Function, AF.
The method according to any of claims 29-36, wherein the terminal device performs as push client.
A method performed by a network server, comprising:

receiving a register message from a second server, wherein the register message indicates a subscriber associated with a terminal device registers with the network server via the second server; and

updating the terminal device information in the network server; and

sending a de-register message to a first server, wherein the de-register message indicates unbinding of the terminal device from the first server;
The method according to claim 38, wherein the first server comprises a current Proxy Call State Control Function, P-CSCF, via which the subscriber associated with the terminal device has been already registered with the network server.
The method according to any of claims 38-39, wherein the second server comprises a new P-CSCF, and the subscriber associated with the terminal device is migrated from the current P-CSCF to the new P-CSCF.
The method according to any of claims 38-40, wherein the network server comprises a Service Capability Server/Application Server, SCS/AS, or Application Function, AF.
The method according to any of claims 38-41, wherein the terminate device performs as push client.
A first server, comprising:

one or more processors; and

one or more memories comprising computer program codes,

the one or more memories and the computer program codes configured to, with the one or more processors, cause the first server at least to perform the method according to any one of claims 1-15.
A second server, comprising:

one or more processors; and

one or more memories comprising computer program codes,

the one or more memories and the computer program codes configured to, with the one or more processors, cause the second server at least to perform the method according to any one of claims 16-28.
A device, comprising:

one or more processors; and

one or more memories comprising computer program codes,

the one or more memories and the computer program codes configured to, with the one or more processors, cause the device at least to perform the method according to any one of claims 29-37.
A network server, comprising:

one or more processors; and

one or more memories comprising computer program codes,

the one or more memories and the computer program codes configured to, with the one or more processors, cause the network server at least to perform the method according to any one of claims 38-42.
A computer-readable medium having computer program codes embodied thereon for use with a computer, wherein the computer program codes comprise codes for performing the method according to any one of claims 1-15.
A computer-readable medium having computer program codes embodied thereon for use with a computer, wherein the computer program codes comprise codes for performing the method according to any one of claims 16-28.
A computer-readable medium having computer program codes embodied thereon for use with a computer, wherein the computer program codes comprise codes for performing the method according to any one of claims 29-37.
A computer-readable medium having computer program codes embodied thereon for use with a computer, wherein the computer program codes comprise codes for performing the method according to any one of claims 38-42.