First ims node, second server, subscriber server and method in a communication network

Abstract

A method performed by a first IMS node for handling establishment of a session for communication with a user equipment (UE) in a communication network is provided. The UE is assigned a first server for session control of the session. The first IMS node sends (203) a request to a subscriber server associated with the UE. The request requests assistance data for selecting a second server to be assigned to the UE for session control. When receiving the requested assistance data from the subscriber server, the first IMS node selects (205) a second server based on the requested assistance data to be assigned to the UE for session control. The first IMS node sends (206) an invitation to the selected second server. The invitation relates to establishing the session. The invitation comprises an indication indicating that the selected second server is selected to replace the first server. The indication triggers the selected second server to indicate to the subscriber server to register an address of the selected second server in the subscriber server to replace the first server being assigned to the UE for session control. The indication allows the subscriber server to perform the registration to replace the first server with the selected second server to be assigned to the UE for session control of the session.

Description

Technical Field

[0001] The embodiments described herein relate to a first Internet Protocol Multimedia Subsystem (IMS) node, a second server, a subscriber server, and methods therein. In some aspects, they relate to processing the establishment of a session for communicating with a user equipment (UE) in a communication network. Background Technology

[0002] In a typical wireless communication network, wireless devices (also known as wireless communication devices, mobile stations, stations (STAs), and / or user equipment (UEs)) communicate with one or more core networks (CNs) via a local area network (LAN) or radio access network (RAN), such as a Wi-Fi network. RAN coverage is divided into geographical areas of service or cell areas (which may also be referred to as beams or beam groups), each of which is served by a radio network node, such as a radio access node (e.g., a Wi-Fi access point or radio base station (RBS)). In some networks, this radio network node may also be referred to as, for example, a NodeB, an eNodeB (eNB), or a gNB as used in fifth-generation (5G) telecommunications. A service area or cell area is a geographical area in which radio coverage is provided by a radio network node. Radio network nodes communicate with wireless devices within their range via an air interface operating on radio frequencies.

[0003] The specification for the Evolved Packet System (EPS) (also known as fourth-generation (4G) networks) has been finalized within the 3rd Generation Partnership Project (3GPP), and this work continues in upcoming 3GPP releases, such as the standardization of 5G networks (also known as 5G New Radio (NR)). EPS comprises the Evolved Universal Terrestrial Radio Access Network (E-UTRAN) (also known as Long Term Evolution (LTE) Radio Access Network) and the Evolved Packet Core (EPC) (also known as the System Architecture Evolution (SAE) Core Network). E-UTRAN / LTE is a variant of the 3GPP Radio Access Network where radio network nodes are directly connected to the EPC core network (rather than the RNC used in 3G networks). Generally, in E-UTRAN / LTE, the functionality of the 3G RNC is distributed between the radio network nodes (e.g., eNodeBs in LTE) and the core network. Therefore, the RAN of EPS has a basically "flat" architecture, consisting of radio network nodes directly connected to one or more core networks, meaning they are not connected to the RNC. To compensate for this, the E-UTRAN specification defines a direct interface between radio network nodes, which is referred to as the X2 interface.

[0004] Multi-antenna technology can significantly increase the data rate and reliability of wireless communication systems. Performance is particularly enhanced when both the transmitter and receiver are equipped with multiple antennas (resulting in a multiple-input multiple-output (MIMO) communication channel). Such systems and / or related technologies are commonly referred to as MIMO.

[0005] In addition to faster peak internet connection speeds, 5G is planned to offer significantly higher capacity than existing 4G, allowing for a greater number of mobile broadband users per area unit and enabling gigabytes of data consumption per month and per user, or even unlimited data. This would allow most people to stream high-definition media for hours daily using their mobile devices when Wi-Fi hotspots are unavailable. 5G development also aims to improve support for machine-to-machine communication (also known as the Internet of Things), with goals for lower cost, lower battery consumption, and lower latency compared to 4G devices.

[0006] Internet Protocol (IP) Multimedia Subsystem (IMS) is a well-known 3GPP standard that allows sessions to be established between two or more parties for a wide variety of services, such as voice or video calls, interactive messaging sessions, or third-party specific applications. The protocol chosen by 3GPP is the Session Initiation Protocol (SIP). SIP provides mechanisms for registering UEs and establishing multimedia sessions. The SIP Register method registers the current location of the user agent, while the SIP Invite method establishes a session. IMS is implemented by Public Land Mobile Network (PLMN) operators as the architectural framework for providing IP multimedia services to their subscribers.

[0007] Functional elements in IMS network

[0008] The IMS network comprises several network entities, some of which will be discussed here.

[0009] Home Subscriber Server (HSS)

[0010] HSS is a subscriber database that includes subscriber profiles, performs authentication and authorization, and provides information about the services provided to subscribers, as well as information about subscribers' locations and IP addresses.

[0011] Service Call Session Control Function (S-CSCF)

[0012] The S-CSCF is a SIP server and the central signaling node in the IMS network, performing session control services for the UE. It handles SIP registration and is responsible for forwarding SIP messages to the correct application server. The S-CSCF can also act as a SIP proxy, meaning it accepts requests and either serves them internally or forwards them.

[0013] Inquire about the call session control function (I-CSCF).

[0014] The I-CSCF is a SIP server located at the edge of the management domain. Its IP address is advertised in the domain's Domain Name System (DNS) so that remote servers can find it and use it as a forwarding point for SIP packets to the domain. It queries the HSS to obtain the address of the S-CSCF and assigns it to users performing SIP registration, and also forwards SIP requests or responses to the S-CSCF.

[0015] 3GPP has recently standardized the IMS architecture over Service-Based Interfaces (SBIs). This replaces the traditional Cx and Sh interfaces to support SBIs, such as those based on Hypertext Transfer Protocol (HTTP) and cloud-native interfaces.

[0016] Several services have been defined in IMS on SBI (which will soon replace the Cx and Sh interfaces). Two of them are listed below:

[0017] • User Equipment Context Management (UECM) - Used to handle IMS registration performed by a given S-CSCF.

[0018] • Subscription Data Management (SDM) - Used to manage subscription data, such as S-CSCF selection information to be used by the I-CSCF.

[0019] SBI allows cloud-native applications to be built on microservices and be as stateless as possible, making scalability and redundancy more efficient. SBI and Representational State Transfer (REST)-ful interfaces interact using stateless methods. This means that the less state the server needs, the more efficient it is in achieving load balancing, failover, and other features. Summary of the Invention

[0020] As part of the development embodiments described herein, the inventors have identified a problem, which will be discussed first.

[0021] Traditional Cx S-CSCF Reselection

[0022] When S-CSCF reselection is required, the I-CSCF requests S-CSCF selection assistance data from the HSS. In this case, an S-CSCF reallocation pending flag is set in the HSS. When the HSS accepts a request to allocate a new S-CSCF to the UE and stores its identifier, this flag is cleared, thus rejecting new requests from different S-CSCFs unless there is another explicit request for S-CSCF selection assistance data from the I-CSCF, and the flag in the HSS is set again.

[0023] In the traditional Cx S-CSCF reselection process, if the S-CSCF identifier differs from the S-CSCF identifier of the currently serving UE, the HSS is not allowed to store the S-CSCF identifier unless an S-CSCF reallocation pending flag is set. If the traditional Cx S-CSCF reselection process is used for IMS on SBI, the I-CSCF may not be able to perform S-CSCF reselection. This could lead to service interruption and prevent the UE from accepting the termination of the communication session.

[0024] The problem is that the traditional Cx S-SCSF reselection process may not be applicable to IMS on SBI.

[0025] In IMS on SBI, it may not be possible to ensure that requests for auxiliary data selection by the S-CSCF originate from the I-CSCF, as SBI is designed to be used by any network function and / or service consumer. Furthermore, setting a flag in the HSS due to the simple acceptance of requests makes the process dependent on future events that may not occur, such as if no S-CSCF contacts the HSS after the flag is set. There is no description of when the flag is reset in legacy Cx, except when the HSS accepts an S-CSCF reselection. SBI operations should be independent of each other whenever possible. They should not leave potentially permanent temporary states in the server, as this assumes a later request that will clear the temporary state. This violates the RESTful and / or SBI principles of stateless interaction. This means that calls and other sessions of UEs served by the S-CSCF are simply rejected if the S-CSCF fails, leading to a higher risk of failed sessions and reduced communication network performance.

[0026] The purpose of the embodiments described herein is to improve the performance of communication networks, including IMS networks.

[0027] According to one aspect of the embodiments herein, this objective is achieved by a method performed by a first IMS node for processing the establishment of a session for communication with a user equipment (UE) in a communication network. The UE is assigned a first server for session control. The first IMS node sends a request to a subscriber server associated with the UE. This request requests auxiliary data for selecting a second server to be assigned to the UE for session control. Upon receiving the requested auxiliary data from the subscriber server, the first IMS node selects a second server based on the requested auxiliary data to be assigned to the UE for session control. The first IMS node sends an invitation to the selected second server. This invitation relates to establishing a session. The invitation includes an indication that the selected second server is chosen to replace the first server. This indication triggers the selected second server to instruct the subscriber server to register the address of the selected second server in the subscriber server to be assigned to the UE for session control in place of the first server. This indication allows the subscriber server to perform registration to be assigned to the UE for session control of the session using the selected second server instead of the first server.

[0028] According to another aspect of the embodiments herein, this objective is achieved by a method performed by a second server for processing the establishment of a session for communication with a user equipment (UE) in a communication network. The UE is assigned a first server for session control. The second server receives an invitation from a first IMS node. This invitation relates to establishing a session. The invitation includes an indication that the second server is selected to replace the first server assigned to the UE for session control. Triggered by this indication, the second server sends a registration request to a subscriber server associated with the UE. The registration request includes the indication. The registration request requests the subscriber server to register the address of the selected second server in the subscriber server to replace the first server assigned to the UE for session control. This indication allows the subscriber server to perform registration to replace the first server in the session control assigned to the UE for the session.

[0029] According to another aspect of the embodiments herein, this objective is achieved by a method performed by a subscriber server for processing the establishment of a session for communication with a user equipment (UE) in a communication network. The UE is assigned a first server for session control. The subscriber server is associated with the UE. The subscriber server receives a request from a first IMS node associated with the UE. This request requests auxiliary data for selecting a second server to be assigned to the UE for session control. The subscriber server sends the requested auxiliary data to the IMS node. The subscriber server receives a registration request from the second server, the registration request including an indication that the second server has been selected based on the auxiliary data to replace the first server assigned to the UE for session control. The registration request, including this indication, requests and allows the subscriber server to register the address of the selected second server in the subscriber server to replace the first server assigned to the UE for session control. Based on the registration request including this indication, the subscriber server performs registration to replace the first server with the selected second server for session control of the session.

[0030] According to another aspect of the embodiments herein, this objective is achieved by a first IMS node configured to handle the establishment of sessions for communication with a user equipment (UE) in a communication network. The UE is adapted to be assigned a first server for session control.

[0031] The first IMS node is also configured as follows:

[0032] A request is sent to a subscriber server suitable for association with the UE, the request being adapted to request auxiliary data for selecting a second server to be assigned to the UE for session control.

[0033] When the requested auxiliary data is received from the subscriber server, a second server is selected and assigned to the UE for session control based on the requested auxiliary data.

[0034] Send an invitation to the selected second server, the invitation being suitable for establishing a session, the invitation also being suitable for including an indication suitable for indicating that the selected second server is chosen to replace the first server, and

[0035] This instruction is also adapted to trigger the selected second server to instruct the subscriber server to register the address of the selected second server in the subscriber server, in place of the first server being assigned to the UE for session control.

[0036] The instruction is also adapted to allow the subscriber server to perform registration so that a second server selected in place of the first server is assigned to the UE for session control of the session.

[0037] According to another aspect of the embodiments herein, this objective is achieved by a second server configured to handle the establishment of sessions for communication with a user equipment (UE) in a communication network. The UE is adapted to be assigned to a first server for session control. The second server is further configured to:

[0038] Receive an invitation from the first IMS node, the invitation being suitable for establishing a session, the invitation also being suitable for including an indication that a second server is selected to replace the first server assigned to the UE for session control, and

[0039] Triggered by this indication, a registration request is sent to a subscriber server suitable for association with the UE. This registration request is adapted to include the indication and also to request the subscriber server to register the address of the selected second server in its service, in lieu of the first server being assigned to the UE for session control.

[0040] The instruction is adapted to allow the subscriber server to perform registration so that a second server selected in place of the first server is assigned to the UE for session control of the session.

[0041] According to another aspect of the embodiments herein, this objective is achieved by a subscriber server configured to handle the establishment of sessions for communication with a user equipment (UE) in a communication network. The UE is adapted to be assigned a first server for session control. The subscriber server is adapted to be associated with the UE. The subscriber server is further configured to:

[0042] Receive a request from a first IMS node suitable for association with the UE, the request being adapted to request auxiliary data for selection of a second server to be assigned to the UE for session control.

[0043] Send the requested auxiliary data to the IMS node.

[0044] A registration request is received from a second server, the registration request being adapted to include an indication that the second server has been selected based on auxiliary data to replace the first server assigned to the UE for session control. The registration request, including this indication, is further adapted to request and allow the subscriber server to register the address of the selected second server in the subscriber server database, in place of the first server assigned to the UE for session control.

[0045] Based on the registration request including this instruction, registration is performed to assign the selected second server to the UE for session control of the session.

[0046] Since the first IMS node receives selection assistance data for selecting a second server to be assigned to the UE for session control, and after selecting the second server based on the selection assistance data, the first IMS node sends an indication to the second server that the second server has been selected for assignment to the UE, the subscriber server can register the address of the second server to be assigned to the UE for session control in place of the first server. This is performed by the second server sending a registration request to the subscriber server, which includes an indication allowing the subscriber server to be assigned to the UE for session control using the selected second server instead of the first server. In this way, an efficient mechanism for improving the selection of a second server to be assigned to the UE for session control is implemented, which leads to a reduced risk of failed sessions, thereby improving the performance of the communication network including the IMS network.

[0047] The embodiments described herein offer the advantage of achieving high availability for IMS on SBI with minimal signaling, reducing the risk of failed sessions, and reducing load in areas such as RAN, EPC, 5GC, and / or IMS. Attached Figure Description

[0048] Examples of embodiments described herein are described in more detail with reference to the accompanying drawings, in which:

[0049] Figure 1a This is a schematic block diagram illustrating an embodiment of a communication network.

[0050] Figure 1b This is a schematic block diagram illustrating an embodiment of an IMS network.

[0051] Figure 2 This is a flowchart depicting an embodiment of the method in the first IMS node.

[0052] Figure 3 This is a flowchart depicting an embodiment of the method in the second server.

[0053] Figure 4 This is a flowchart depicting an embodiment of a method in a subscriber server.

[0054] Figure 5a This is a sequence diagram depicting an embodiment of the method.

[0055] Figure 5b This is a sequence diagram depicting an embodiment of the method.

[0056] Figures 6a to 6b This is a schematic block diagram illustrating an embodiment of the first IMS node.

[0057] Figures 7a to 7b This is a schematic block diagram illustrating an embodiment of the second server.

[0058] Figures 8a to 8b This is a schematic block diagram illustrating an embodiment of a subscriber server.

[0059] Figure 9 The diagram schematically illustrates a telecommunications network connected to a host computer via an intermediate network.

[0060] Figure 10 This is a general block diagram of a host computer that communicates with user equipment via a base station through a partial wireless connection.

[0061] Figures 11 to 14 This is a flowchart illustrating a method implemented in a communication system that includes a host computer, a base station, and user equipment. Detailed Implementation

[0062] The embodiments described herein relate to a communication network and the establishment of a session for communicating with a UE assigned a first server for session control.

[0063] The example embodiments described herein provide methods that improve the processing of session establishment for communication with a UE by allowing a first IMS node to indicate in an invitation to a second server that the second server is selected instead of the first server being assigned to the UE for session control. This allows the second server to send an indication to the subscriber server, when requesting the subscriber server to register the address of the second server, to replace the first server being assigned to the UE for session control.

[0064] Furthermore, exemplary embodiments herein provide methods that improve the processing of session establishment for communication with the UE by allowing subscribers to register the address of a second server instead of a first server being assigned to the UE for session control, and by receiving an indication that a second server has been selected instead of a first server being assigned to the UE. This results in a more efficient method for processing the establishment of sessions for communication with the UE.

[0065] Figure 1a This is a schematic overview diagram depicting a communication network 100 in which embodiments of the present invention can be implemented. Communication network 100 includes one or more RANs and one or more CNs. Communication network 100 can use a variety of different technologies, such as Wi-Fi, LTE, LTE-Advanced, 5G, New Radio (NR), Wideband Code Division Multiple Access (WCDMA), Global System for Mobile Communications / Enhanced Data Rate GSM Evolution (GSM / EDGE), Global Microwave Interoperability Access (WiMax), or Ultra Mobile Broadband (UMB), to name just a few possible implementations. The embodiments described herein relate to a technology trend of particular interest recently in the context of 5G; however, the embodiments are also applicable to further developments of existing wireless communication systems, such as WCDMA and LTE.

[0066] The communication network 100 also includes an Internet Protocol (IP) Multimedia Subsystem (IMS) network 102, in which the IMS network 102, a first IMS node 110, a first server 131, a second server, and a subscriber server 140 operate. The IMS network 102 is an architecture for transmitting media content via IP packet switching.

[0067] Multiple network nodes operate in the communication network 100, such as network node 105. Network node 105 provides radio coverage in multiple cells, which may also be referred to as beams or groups of beams, such as cell 10 provided by network node 105.

[0068] Network node 105 can be any of the following: an NG-RAN node, a transmitting and receiving point, such as a base station, a radio access network node (e.g., a wireless local area network (WLAN) access point or access point station (AP STA)), an access controller, a base station such as a radio base station (e.g., NodeB, evolved Node B (eNB, eNodeB), gNB, base transceiver station, radio remote unit, access point base station, base station router, transmission device of a radio base station, stand-alone access point, or any other network element capable of communicating with wireless devices within the service area served by network node 105 according to, for example, a first radio access technology and the terminology used). Network node 105 can be referred to as a serving network node and communicates with UEs such as UE 121 and UE 122 using downlink (DL) transmissions to UEs 121 and 122 and uplink (UL) transmissions from UEs 121 and 122.

[0069] One or more UEs operate in communication network 100, such as, for example, UE 121 and UE 122. According to the example scenario herein, UE 121 may be referred to as calling UE 121, and UE 122 may be referred to as called UE 122. UE 121 and UE 122 may also be referred to as devices, IoT devices, mobile stations, non-access point (non-AP) STAs, STAs, user equipment and / or wireless terminals, application servers (AS), services, public numbers, communicating with one or more CNs via one or more access networks (ANs) (e.g., RANs). Those skilled in the art should understand that "wireless device" is a non-limiting term, meaning any terminal, wireless communication terminal, user equipment, machine-type communication (MTC) device, device-to-device (D2D) terminal, radio device in a vehicle, or node (e.g., smartphone, laptop, mobile phone, sensor, relay, mobile tablet, or even a small base station communicating within a cell).

[0070] The first IMS node 110 can be used to forward incoming IMS signaling to the UE 122 via intermediate nodes (such as, for example, the first server 131 and the second server 132), and can be, for example, an I-CSCF.

[0071] The first server 131 and the second server 132 can be used to perform session control services for UE 122, and can be, for example, S-CSCF.

[0072] Subscriber server 140 can be used to process subscriber data for UE 122, and can be, for example, an HSS.

[0073] The method described herein can be executed by the first IMS node 110, the first network node 131, and the subscriber server 140. Alternatively, it may include, for example, [the following methods are described]. Figure 1a The distributed nodes (DNs) and functions in Cloud 135 shown can be used to perform or partially perform the methods described herein.

[0074] Figure 1b A schematic overview diagram of an IMS network 102 according to an example scenario to which embodiments of this document may be applied is shown. IMS network 102 includes one or more IMS nodes, such as a first IMS node 110. IMS network 102 also includes a first server 131, a second server 132, and a subscriber server 140. The first IMS node 110 can communicate with the first server 131 and the second server 132, communicate with the subscriber server 140, an end node (e.g., calling UE 121), and communicate with UE 122 through either the first server 131 or the second server 132. When a session for communication between UE 122 and, for example, an end node is established, SIP signals are transmitted through the first IMS node 110 and either the first server 131 or the second server 132. If the first server 131, assigned to UE 122 for session control, fails, becomes unavailable, or returns an error message, then the first IMS node 110 must select another server (e.g., the second server 132) and assign it to UE 122 for session control in order to establish a session for communication.

[0075] Several embodiments will now be described, some of which may be considered alternatives, while others may be used in combination.

[0076] Figure 2An example embodiment of a method for processing the establishment of a session for communication with UE 122 in communication network 100, performed by a first IMS node 110, is shown. The session for communication may refer to a multimedia session, voice call, video call, or SMS over IMS. Establishing a session may refer to establishing, for example, the aforementioned multimedia session, voice call, video call, or SMS over IMS. Processing the establishment may refer to triggering a multimedia telephony application. UE 122 is assigned to a first server 131 for session control. When used herein, assigning to UE 122 may mean that subscriber server 140 has registered, for example, the first server 131 for session control in the subscriber data of UE 122. When used herein, session control may refer to controlling services triggered by an application server (AS), such as controlling the duration of the session to avoid excessively long call durations.

[0077] There may be any one or more of the following: the first IMS node 110 may be an I-CSCF node, the first server 131 may be an S-CSCF node, the second server may be an S-CSCF node, and the subscriber node 140 may be an HSS node.

[0078] This method includes any one or more of the following actions, which can be performed in any suitable order. Optional actions include... Figure 2 As shown in the dashed box in the image.

[0079] Action 201

[0080] In some embodiments, when a communication session is established with UE 122, an invitation request can be sent from an end node such as the calling UE 121 to the first IMS node 110.

[0081] In these embodiments, the first IMS node 110 may receive an invitation request from an end node (e.g., calling UE 121). The invitation request includes an invitation related to establishing a session for communication with UE 122. The invitation request may be, for example, a SIP invitation request or a SIP message request.

[0082] Action 202

[0083] The first server 131 is assigned to UE 122 for session control. Therefore, the first IMS node 110 can direct any incoming requests or other messages sent to the called UE 122 to the server node currently assigned to UE 122.

[0084] Therefore, the first IMS node 110 can send the received invitation to the first server 131 assigned to the UE 122. This invitation can be, for example, a SIP invitation request or a SIP message request.

[0085] Action 203

[0086] The first server node 131 may be unavailable, or another server node may be better suited to handle the establishment of a session with UE 122. Then the first IMS node 110 needs to select a new server node for session control.

[0087] In order to select a suitable server node for session control of UE 122, the first IMS node 110 needs to select auxiliary data.

[0088] The first IMS node 110 sends a request to the subscriber server 140 associated with the UE 122. This request is for selecting a second server to be assigned to the UE 122 for auxiliary data used for session control. The auxiliary data selection may include, for example, data related to the capabilities of the second server 132. The subscriber server may be an SBI-enabled subscriber server, meaning it supports the services required for IMS on the SBI, such as, for example, nhss-ims-uecm and nhss-ims-sdm. When used herein, the term "SBI-enabled" may refer to supporting IMS on an SBI using stateless transactions.

[0089] Depending on the interface used for communication between the first IMS node 131 and the subscriber server 140, different protocols may be used for this request.

[0090] In some embodiments, the request can be any one or more of the following: a Hypertext Transfer Protocol (HTTP) GET request and a Diameter request message. When the request is an HTTP GET request, the interface used can be the SBI interface. When the request is a Diameter request, the interface used can be the Cx interface.

[0091] As described above, the first server node 131 may become unavailable for some reason, such as another server node may be better suited to handle the establishment of a session with UE 122.

[0092] For example, the request can be sent when any of the following occurs: the first IMS node 110 determines that the first server 131 is unavailable when establishing the session, or decides that the first server 131 is replaced when establishing the session. The reasons for determining that the first server 131 is unavailable and replacing it during session establishment can include, for example, any one or more of the following: load balancing between the first server 131, the second server 132, and any one or more third servers; the first server 131 being offline; or the first server 131 sending an error message, such as a SIP error message, to the IMS node 110 in response to the invitation.

[0093] Action 204

[0094] As described above, the first IMS node 110 requests auxiliary data for selecting a second server 132 to be assigned to the UE 122. In these embodiments, the first IMS node 110 receives, for example, auxiliary data from the subscriber server 140 for selecting the second server 132 to be assigned to the UE 122 for session control.

[0095] Action 205

[0096] The received auxiliary data assists the first IMS node 110 in establishing an appropriate basis for selecting a second server 132 to be assigned to the UE 122. For example, the auxiliary data may include an integer indicating that the server (e.g., the second server 132) is the preferred server. The auxiliary data may also include capabilities supported by the server (e.g., the second server 132). The first IMS node 110 may have already stored a mapping between the auxiliary data and the selectable servers.

[0097] The first IMS node 110 selects a second server 132 to assign to the UE 122 for session control. Therefore, when requested auxiliary data is received from the subscriber server 140, this selection is based on the requested auxiliary data.

[0098] Action 206

[0099] When the first IMS node 110 has selected the second server 132 to be assigned to the UE 122 for session control, the first IMS node 110 sends the received invitation to the selected second server 132.

[0100] The first IMS node 110 sends an invitation to the selected second server 132. This invitation is related to establishing a session.

[0101] The invitation includes an instruction that a second server 132 is selected to replace the first server 131. This instruction triggers the selected second server 132 to instruct the subscriber server 140 to register the address of the selected second server 132 in the subscriber server 140, in place of the first server 131 being assigned to the UE 122 for session control.

[0102] This instruction allows subscriber server 140 to perform registration to be assigned to UE 122 for session control of the session, replacing first server 131 with the selected second server 132. By sending an instruction to the second server node 132, subscriber server 140 is allowed to be assigned to UE 122 for session control with the second server 132 instead of first server 131, reducing the risk of communication session failure with minimal signaling. Minimal signaling means that the only signaling required for assigning second server 132 to UE 122 for session control is the signaling required to instruct subscriber server 140 that the selected second server 132 has been chosen to replace first server 131.

[0103] In some embodiments, the indication is included in the routing header of an invitation, and the invitation is a SIP request message. The invitation can also be a SIP invitation request or a SIP message request. When included in the routing header of an invitation, the indication can be a parameter, such as a URI parameter, or a token or cookie in the URI. The indication can also be included in a header of the invitation that is different from the routing header.

[0104] The method will now be described from the perspective of the second server 132.

[0105] Figure 3 An example embodiment of a method for processing the establishment of a session for communication with UE 122 in communication network 100, performed by a second server 132, is shown. UE 122 is assigned to a first server 131 for session control. When used herein, assigning a first server 131 to UE 122 means that subscriber server 140 has registered the first server 131, for example, for session control, in the subscriber data of UE 122. Any one or more of the following may be present: the first IMS node 110 may be an I-CSCF node, the first server 131 may be an S-CSCF node, the second server may be an S-CSCF node, and subscriber node 140 may be an HSS node.

[0106] This method includes any one or more of the following actions, which can be performed in any suitable order. Optional actions include... Figure 3 As shown in the dashed box in the image.

[0107] Action 301

[0108] As described above, when the first IMS node 110 has selected the second server 132 to be assigned to the UE 122 for session control, the first IMS node 110 sends the received invitation to the selected second server 132.

[0109] The second server 132 receives an invitation from the first IMS node 110. This invitation relates to establishing a session. The invitation includes an indication that the second server 132 has been selected to replace the first server 131 and assigned to the UE 122 for session control.

[0110] In some embodiments, the indication is included in the routing header of an invitation, and the invitation is a SIP request message. The invitation may also be, for example, a SIP invitation request or a SIP message request. When included in the routing header of an invitation, the indication may be a parameter, such as a URI parameter, or a token or cookie in the URI. The indication may also be included in a header of the invitation that is different from the routing header.

[0111] As described above, the first server node 131 may become unavailable, or another server node may be better suited to handle the establishment of a session with UE 122. The first IMS node 110 then needs to select a new server node for session control.

[0112] In some embodiments, an invitation from the first IMS node 110 is received when any of the following occurs: the first IMS node 110 determines that the first server 131 is unavailable when establishing a session, or has determined that the first server 131 will be replaced when establishing a session. As described above, the reasons for determining that the first server 131 is unavailable and that the first server 131 will be replaced when establishing a session may include, for example, any one or more of the following: load balancing among the first server 131, the second server 132, and any one or more third servers; the first server 131 is offline; or the first server 131 sends an error message, such as a SIP error message, to the IMS node 110 in response to an invitation sent to the first IMS node 110.

[0113] Action 302

[0114] The second server 132 is selected for session control and needs to be assigned to UE 122 and properly registered in subscriber server 140 in order to successfully establish a session for communication with UE 122.

[0115] According to an embodiment of this document, the second server 132 is triggered by the indication to send a registration request to the subscriber server 140 associated with the UE 122. The registration request includes an indication that the second server 132 is selected to replace the first server 131 and assigned to the UE 122 for session control. The registration request requests the subscriber server 140 to register the address of the selected second server 132 in its own database to replace the first server 131 assigned to the UE 122 for session control. This indication allows the subscriber server 140 to perform registration to replace the first server 131 in the session control assigned to the UE 122 for the session. This indication may be, for example, a parameter in the registration request. This parameter may be, for example, a Boolean parameter or an enumerated event.

[0116] When this indication is a Boolean parameter and is set to true, it can indicate, for example, that the first IMS node 140 has selected the second server 132 to replace the first server 131 and has been assigned to the UE for session control, or that a server reselection has occurred. When set to false, this parameter can indicate, for example, that no server reselection has occurred. When this parameter is not present, it can indicate, for example, that no server reselection has occurred. The server can be, for example, an S-CSCF.

[0117] Depending on the interface used for communication between the second server 132 and the subscriber server 140, different protocols may be used for this request.

[0118] In some embodiments, the registration request is any one or more of the following: an HTTP PUT request and a Diameter request message. When the registration request is an HTTP PUT request, the interface used can be the SBI interface. When the request is a Diameter request, the interface used can be the Cx interface.

[0119] The method will now be described from the perspective of subscriber server 140. Figure 4An example embodiment of a method for processing the establishment of a session for communication with UE 122 in communication network 100, performed by subscriber server 140, is shown. UE 122 is assigned to a first server 131 for session control. Subscriber server 140 is associated with UE 122. When used herein, being assigned to UE 122 means that subscriber server 140 has registered the first server 131, for example, for session control, in the subscriber data of UE 122. Any one or more of the following may be present: the first IMS node 110 may be an I-CSCF node, the first server 131 may be an S-CSCF node, the second server may be an S-CSCF node, and subscriber node 140 may be an HSS node. When used herein, being associated with UE 122 means that subscriber server 140 stores, updates, and processes the subscriber data of UE 122.

[0120] This method includes any one or more of the following actions, which can be performed in any suitable order. Optional actions include... Figure 4 As shown in the dashed box in the image.

[0121] Action 401

[0122] When selecting a new server for session control of UE 122, the first IMS node 110 needs to select auxiliary data.

[0123] Subscriber server 140 receives a request from first IMS node 110 associated with UE 122. This request seeks to select a second server to be assigned to UE 122 for auxiliary data used for session control. The selection of auxiliary data may, for example, include the capabilities of the second server 132. The subscriber server may be an SBI-enabled subscriber server.

[0124] As mentioned above, different protocols can be used for this request, depending on the interface used for communication between the first IMS node and the subscriber server 140.

[0125] Therefore, in some embodiments, the request can be any one or more of the following: an HTTP GET request and a Diameter request message. When the request is an HTTP GET request, the interface used can be the SBI interface. When the request is a Diameter request, the interface used can be the Cx interface.

[0126] The request may be received when any of the following occurs: the first IMS node 110 determines that the first server 131 is unavailable when establishing a session, or decides that the first server 131 is replaced when establishing a session. As described above, deciding that the first server 131 is replaced when establishing a session may include, for example, any one or more of the following: load balancing between the first server 131, the second server 132, and any one or more third servers; the first server 131 being offline; or the first server 131 sending an error message, such as a SIP error message, to the IMS node 110 in response to an invitation sent to the first IMS node 110.

[0127] Action 402

[0128] Subscriber server 140 sends requested auxiliary data to first IMS node 110. This is, for example, a response to a request to select auxiliary data.

[0129] Action 403

[0130] In order to establish a session for communication with UE 122 using the selected second server 132, the selected second server 140 needs to be registered in subscriber server 140 to be assigned to UE 122.

[0131] Subscriber server 140 receives a registration request from second server 132. This registration request includes an indication that second server 132 has been selected based on auxiliary data to replace first server 131 and be assigned to UE 122 for session control. The registration request includes this indication and allows subscriber server 140 to register the address of the selected second server 132 in its own database to replace first server 131 in session control for UE 122. By sending this indication to subscriber server 140, subscriber server 140 is allowed to use second server 132 instead of first server 131 in session control for UE 122, minimizing the risk of communication session failure with minimal signaling. This indication can be, for example, a parameter in the registration request. This parameter can be, for example, a Boolean parameter or an enumerated event.

[0132] When this indication is a Boolean parameter and is set to true, it can indicate, for example, that the first IMS node 140 has selected the second server 132 to replace the first server 131 and has been assigned to the UE for session control, or that a server reselection has occurred. When set to false, this parameter can indicate, for example, that no server reselection has occurred. When this parameter is not present, it can indicate, for example, that no server reselection has occurred. The server can be, for example, an S-CSCF.

[0133] As mentioned above, different protocols can be used for this request, depending on the interface used for communication between the second server 132 and the subscriber server 140.

[0134] Therefore, the registration request can be any one or more of the following: an HTTP PUT request and a Diameter request message. When the registration request is an HTTP PUT request, the interface used can be the SBI interface. When the request is a Diameter request, the interface used can be the Cx interface.

[0135] Action 404

[0136] The subscriber server 140 may notice the presence of an instruction in the received registration request before allowing itself to perform the requested registration.

[0137] Based on the registration request including this instruction, subscriber server 140 performs registration to be assigned to UE 122 for session control of the session using the selected second server 132 instead of the first server 131. By receiving the instruction from the second server node 132, subscriber server 140 is permitted to be assigned to UE 122 for session control using the second server 132 instead of the first server 131, thereby reducing the risk of communication session failure with minimal signaling.

[0138] The embodiments described herein as described above will now be further described and illustrated. The following text applies to any suitable embodiments described above and can be combined with them.

[0139] Figure 5a and Figure 5b Actions 501-515 describe in detail the steps of an implementation example according to embodiments herein. Figure 5a and Figure 5b In this configuration, the first IMS node 110 is referred to as I-CSCF 110, the first server 131 is referred to as S-CSCF-1 131, the second server 132 is referred to as S-SCSF-2-132, the subscriber server 140 is referred to as HSS-SBI 140, the end node (e.g., calling UE 121) is referred to as UE 121, and UE 122 (not shown) is referred to as UE 122. These actions can be performed in any suitable order.

[0140] Action 501

[0141] The I-CSCF 110 of the first IMS node 110 may receive, for example, a SIP invitation request (e.g., an invitation request) from UE 121, which may be an end node, such as the calling UE 121. The invitation request may include an invitation, such as an invitation related to establishing a session for communication with UE 122.

[0142] Action 502

[0143] I-CSCF 110 authorizes this request.

[0144] Action 503

[0145] I-CSCF 110 sends messages, such as an HTTP POST .. / authorization request, to HSS-SBI 140, which can be Subscriber Server 140.

[0146] Action 504

[0147] HSS-SBI 140 checks whether an S-CSCF is assigned to UE 122 and returns the stored S-CSCF name S-CSCF-1 131, which can be the first server 131.

[0148] Action 505

[0149] HSS-SBI 140 sends an HTTP 200 OK message accepting authorization to I-CSCF 110. This message includes the S-CSCF currently assigned to UE 122 for session control, such as S-CSCF-1 131.

[0150] Action 506

[0151] I-CSCF 110 sends, for example, a SIP invitation request to S-CSCF 131, such as an invitation related to establishing a session for communication with UE 122, because it is currently assigned to UE 122.

[0152] Action 507

[0153] In this example, when S-CSCF-1 131 does not respond to, for example, a SIP invitation request (e.g., an invitation related to establishing a session for communication with UE122), I-CSCF 110 determines that S-CSCF reselection is required.

[0154] Action 508

[0155] I-CSCF 110 sends a request for S-CSCF selection assistance data to HSS-SBI 140, such as HTTP GET .. / scscf-selection-assistance-info, which is a request for selecting a second server 132 to be assigned to UE 122 for session control assistance data.

[0156] Action 509

[0157] HSS-SBI 140 responds to I-CSCF 110 by sending a response (e.g., an HTTP 200 OK message, such as requested auxiliary data, including S-CSCF selection auxiliary data). The S-CSCF selection auxiliary data may, for example, include S-CSCF capabilities.

[0158] Action 510

[0159] I-CSCF 110 selects a different S-CSCF (e.g., S-CSCF-2 132, which could be a second server 132) to be assigned to UE 122 for session control. This selection is based on S-CSCF selection auxiliary data.

[0160] Action 511

[0161] After selecting S-CSCF-2 132 for assignment to UE 122 for session control, I-CSCF 110 sends, for example, a SIP invitation request to S-CSCF-2 132, such as an invitation related to establishing a session for communication with UE 122. For example, the SIP invitation request includes indications, such as that S-CSCF-2 132 has been selected to replace S-CSCF-1 131 assigned to UE 122 for session control, indicating that an S-CSCF reselection has occurred. This can be done in the form of a new URI parameter included in, for example, the SIP routing header in the SIP invitation request, such as:

[0162] uri-parameter=transport-param / user-param / method-param / ttl-param / maddr-param / lr-param / orig / other-param

[0163] orig = "orig"

[0164] reselect="reselect"

[0165] Action 512

[0166] Since S-CSCF-2 132 was not assigned to UE 122 for session control and was triggered by this indication, S-CSCF-2 132 stored its address in HSS-SBI 140, thus replacing S-CSCF-1 131 which was assigned to UE 122.

[0167] Action 513

[0168] S-CSCF-2 132 sends a registration request to HSS-SBI 140, such as an HTTP PUT .. / scscf-registration request, or a registration request such as requesting HSS-SBI 140 to register the address of S-CSCF-2 132 in place of S-CSCF-1 131 assigned to UE 122 for session control. The registration request includes indications, such as indications that S-CSCF-2 132 has been selected to replace S-CSCF-1 131 assigned to UE 122 for session control, or indications that an S-CSCF reselection has occurred, such as:

[0169]

[0170]

[0171] Action 514

[0172] The registration request requests HSS-SBI 140 to register the address of S-CSCF-2 132 in HSS-SBI 140. Based on the registration request, in order to replace S-CSCF-1 131 being assigned to UE 122 for session control, HSS-SBI 140 assigns S-CSCF-2 132 to UE 122 for session control, such as performing the registration of S-CSCF-2 132, thereby replacing S-CSCF-1 131 with S-CSCF-2 132. The registration request includes indications, such as an indication that S-CSCF-2 132 is selected to replace S-CSCF-1 131 being assigned to UE 122 for session control. This indication allows HSS-SBI 140 to register the address of the selected S-CSCF-2 132 in HSS-SBI 140, in place of S-CSCF-1 131 being assigned to UE 122 for session control.

[0173] Action 515

[0174] After registration is performed, HSS-SBI 140 can send a message, such as HTTP 200 OK, to S-CSCF-2 132 to confirm the registration of S-CSCF-2 132 in HSS-SBI 140, in place of S-CSCF-1 131 being assigned to UE122 for session control.

[0175] To perform the above-described actions, the first IMS node 110 may include... Figure 6a and Figure 6bThe arrangement is shown. The first IMS node 110 is configured to handle the establishment of sessions for communication with user equipment UE 122 in the communication network 100. UE 122 is adapted to be assigned to a first server 131 for session control.

[0176] The first IMS node 110 may include an input and output interface 600 configured to communicate with network nodes such as a first server 131, a second server 132, a subscriber server 140, and a UE 122. The input and output interface may include a wireless receiver (not shown) and a wireless transmitter (not shown).

[0177] The first IMS node 110 is also configured, for example, to send a request to a subscriber server 140 suitable for association with UE 122 via a transmission unit 610 in the first IMS node 110. This request is adapted to request auxiliary data for selecting a second server to be assigned to UE 122 for session control.

[0178] The request can also be any one or more of the following: HTTP GET request and SIP request message.

[0179] The request may also be sent if either of the following occurs: the first IMS node 110 determines that the first server 131 is unavailable when establishing a session, or determines that the first server 131 is replaced when establishing a session.

[0180] The first IMS node 110 is also configured to, for example, send an invitation to the selected second server 132 via a sending unit 610 in the first IMS node 110. This invitation is adapted to relate to establishing a session. The invitation is also adapted to include an indication suitable for instructing the selected second server 132 to be selected in place of the first server 131. This indication is also adapted to trigger the selected second server 132 to instruct the subscriber server 140 to register the address of the selected second server 132 in the subscriber server 140, in place of the first server 131, for session control of the UE 122. This indication is also adapted to allow the subscriber server 140 to perform registration for session control of the session, in which the selected second server 132 is assigned to the UE 122 in place of the first server 131.

[0181] There may be any one or more of the following: the indication may also be adapted to be included in the routing header of an invitation, and the invitation may also be adapted to be a SIP request message.

[0182] The first IMS node 110 can also be configured, for example, to send an invitation to a first server 131 suitable for being assigned to UE 122 via a sending unit 610 in the first IMS node 110.

[0183] The first IMS node 110 is also configured, for example, via the selection unit 620 in the first IMS node 110, to select a second server 132 based on the requested auxiliary data received from the subscriber server 140 for session control.

[0184] The first IMS node 110 can also be configured to receive an invitation request from an end node (e.g., calling UE 121) via a receiving unit 630 in the first IMS node 110. The invitation request is suitable to include an invitation related to establishing a session for communication with UE 122.

[0185] It can be done through a corresponding processor or one or more processors (e.g., Figure 6a The embodiments of the present invention are implemented by a processor 640 of the processing circuitry in the first IMS node 110 shown herein, and corresponding computer program code for performing the functions and actions of the embodiments herein. The program code may also be provided as a computer program product, for example, in the form of a data carrier carrying the computer program code that executes the embodiments of the present invention when loaded onto the first IMS node 110. Such a carrier may be in the form of a CD-ROM. However, it may also be other data carriers such as memory sticks. The computer program code may also be provided as plain program code on a server and downloaded to the first IMS node 110.

[0186] The first IMS node 110 may further include a memory 650, which includes one or more memory cells. The memory 650 includes instructions executable by the processor 640 in the first IMS node 110. The memory 650 is arranged to store, for example, information, messages, instructions, requests, selection data, communication data, and applications that execute the methods described herein when executed in the first IMS node 110.

[0187] In some embodiments, the computer program 660 includes instructions that, when executed by at least one corresponding processor 640, cause at least one processor 640 of the first IMS node 110 to perform the aforementioned actions.

[0188] In some embodiments, the corresponding carrier 670 includes a corresponding computer program 660, wherein the carrier 670 is one of an electronic signal, an optical signal, an electromagnetic signal, a magnetic signal, an electrical signal, a radio signal, a microwave signal, or a computer-readable storage medium.

[0189] Those skilled in the art will also understand that the cells in the first IMS node 110 described above may refer to a combination of analog and digital circuitry, and / or one or more processors configured with (e.g., stored in the first IMS node 110) software and / or firmware, which, when executed by the respective one or more processors (e.g., processors), performs as described above. One or more of these processors, along with other digital hardware, may be included in a single application-specific integrated circuit (ASIC), or several processors and various digital hardware may be distributed across several separate components, whether individually packaged or assembled into a system-on-a-chip (SoC).

[0190] To perform the above-described actions, the second server 132 may include... Figure 7a and Figure 7b The arrangement is shown. The second server 132 is configured to handle the establishment of sessions for communication with the UE 122 in the communication network 100. The UE 122 is adapted to be assigned to the first server 131 for session control.

[0191] The second server 132 may include an input and output interface 700 configured to communicate with network nodes such as the first IMS node 110, the first server 131, the subscriber server 140, and the UE 122. The input and output interface may include a wireless receiver (not shown) and a wireless transmitter (not shown).

[0192] The second server 132 is also configured to receive an invitation from the first IMS node 110, for example, via a receiving unit 710 in the second server 132. This invitation is adapted to relate to establishing a session. The invitation is also adapted to include an indication that the second server 132 is selected to replace the first server 131 and assigned to the UE 122 for session control.

[0193] There may be any one or more of the following: the indication may also be suitable to be included in the routing header of an invitation, and the invitation may also be suitable to be a SIP request message.

[0194] An invitation from the first IMS node 110 may also be accepted if the first IMS node 110 determines that the first server 131 is unavailable when establishing a session, or has decided that the first server 131 will be replaced when establishing a session.

[0195] The second server 132 is also configured, for example, to send a registration request to a subscriber server 140 suitable for association with UE 122, triggered by the indication via a sending unit 720 in the second server 132. The registration request is adapted to include the indication. The registration request is also adapted to request the subscriber server 140 to register the address of the selected second server 132 in the subscriber server 140, in place of the first server 131 assigned to UE 122 for session control. The indication is adapted to allow the subscriber server 140 to perform registration to replace the first server 131 in the session control assigned to UE 122 for the session.

[0196] Registration requests can also be any one or more of the following: HTTP PUT requests and SIP request messages.

[0197] It can be done through a corresponding processor or one or more processors (e.g., Figure 7a The embodiments of the present invention are implemented by the processor 730 of the processing circuitry in the second server 132 shown herein, and corresponding computer program code for performing the functions and actions of the embodiments herein. The program code may also be provided as a computer program product, for example, in the form of a data carrier carrying the computer program code that executes the embodiments of the present invention when loaded onto the second server 132. Such a carrier may be in the form of a CD-ROM. However, it may also be other data carriers such as memory sticks. The computer program code may also be provided as pure program code on the server and may be downloaded to the second server 132.

[0198] The second server 132 may also include a memory 740, which includes one or more memory units. The memory 740 includes instructions executable by the processor 730 in the second server 132. The memory 740 is arranged to store, for example, information, messages, instructions, requests, selection data, communication data, and applications that execute the methods described herein when executed in the second server 132.

[0199] In some embodiments, the computer program 750 includes instructions that, when executed by at least one corresponding processor 730, cause at least one processor 730 of the second server 132 to perform the aforementioned actions.

[0200] In some embodiments, the corresponding carrier 760 includes a corresponding computer program 750, wherein the carrier 760 is one of an electronic signal, an optical signal, an electromagnetic signal, a magnetic signal, an electrical signal, a radio signal, a microwave signal, or a computer-readable storage medium.

[0201] Those skilled in the art will understand that the units in the second server 132 as described above can refer to a combination of analog and digital circuitry, and / or one or more processors configured with (e.g., stored in the second server 132) software and / or firmware, which execute as described above when executed by the respective one or more processors (e.g., processors). One or more of these processors, along with other digital hardware, may be included in a single application-specific integrated circuit (ASIC), or several processors and various digital hardware may be distributed across several separate components, whether individually packaged or assembled into a system-on-a-chip (SoC).

[0202] To perform the above-described actions, subscriber server 140 may include... Figure 8a and Figure 8b The arrangement is shown. Subscriber server 140 is configured to handle the establishment of sessions for communication with UE 122 in communication network 100. UE 122 is adapted to be assigned to a first server 131 for session control, and subscriber server 140 is adapted to be associated with UE 122.

[0203] Subscriber server 140 may include input and output interfaces 800 configured to communicate with network nodes such as first IMS node 110, first server 131, and second server 132. The input and output interfaces may include a wireless receiver (not shown) and a wireless transmitter (not shown).

[0204] Subscriber server 140 is also configured to receive, for example, a request from a first IMS node 110 adapted to be associated with UE 122 via receiving unit 810 in subscriber server 140. This request is adapted to request auxiliary data for selecting a second server to be assigned to UE 122 for session control.

[0205] The request can also be any one or more of the following: HTTP GET request and SIP request message.

[0206] The request may also be accepted if either of the following occurs: the first IMS node 110 determines that the first server 131 is unavailable when establishing a session, or determines that the first server 131 is replaced when establishing a session.

[0207] Subscriber server 140 is also configured to receive a registration request from second server 132, for example, via receiving unit 810 in subscriber server 140. The registration request is adapted to include an indication that second server 132 has been selected based on auxiliary data to replace first server 131 assigned to UE 122 for session control. The registration request including this indication is also adapted to request and permit subscriber server 140 to register the address of the selected second server 132 in subscriber server 140, in place of first server 131 assigned to UE 122 for session control.

[0208] Registration requests can also be any one or more of the following: HTTP PUT requests and SIP request messages.

[0209] Subscriber server 140 is also configured to send auxiliary data of the request to first IMS node 110, for example, through sending unit 820 in subscriber server 140.

[0210] Subscriber server 140 is also configured, for example, via execution unit 830 in subscriber server 140, to perform registration based on a registration request including the instruction, to be assigned to UE 122 for session control of the session by replacing the first server 131 with the selected second server 132.

[0211] It can be done through a corresponding processor or one or more processors (e.g., Figure 8a The embodiments of the present invention are implemented by a processor 840 of the processing circuitry in the subscriber server 140 shown herein, and corresponding computer program code for performing the functions and actions of the embodiments herein. The program code may also be provided as a computer program product, for example, in the form of a data carrier carrying the computer program code that executes the embodiments of the present invention when loaded onto the subscriber server 140. Such a carrier may be in the form of a CD-ROM. However, it may also be other data carriers such as memory sticks. The computer program code may also be provided as plain program code on a server and may be downloaded to the subscriber server 140.

[0212] Subscriber server 140 may also include memory 850, which includes one or more memory units. Memory 850 includes instructions executable by processor 840 in the first subscriber server 140. Memory 850 is arranged to store, for example, information, messages, instructions, requests, selection data, communication data, and applications that execute the methods described herein when executed in subscriber server 140.

[0213] In some embodiments, the computer program 860 includes instructions that, when executed by at least one processor 840, cause at least one processor 840 of the subscriber server 140 to perform the aforementioned actions.

[0214] In some embodiments, the corresponding carrier 870 includes a corresponding computer program 860, wherein the carrier 870 is one of an electronic signal, an optical signal, an electromagnetic signal, a magnetic signal, an electrical signal, a radio signal, a microwave signal, or a computer-readable storage medium.

[0215] Those skilled in the art will understand that the units in the first subscriber server 140 as described above can refer to a combination of analog and digital circuitry, and / or one or more processors configured with software and / or firmware (e.g., stored in the subscriber server 140), which execute as described above when executed by the respective one or more processors (e.g., processors). One or more of these processors, along with other digital hardware, may be included in a single application-specific integrated circuit (ASIC), or several processors and various digital hardware may be distributed across several separate components, whether individually packaged or assembled into a system-on-a-chip (SoC).

[0216] refer to Figure 9 According to an embodiment, the communication system includes a telecommunications network 3210 (e.g., a 3GPP-type cellular network), which includes an access network 3211 (e.g., a radio access network) and a core network 3214. The access network 3211 includes multiple base stations 3212a, 3212b, and 3212c (e.g., AP STA NB, eNB, gNB, or other types of wireless access points), each base station defining a corresponding coverage area 3213a, 3213b, or 3213c. Each base station 3212a, 3212b, or 3212c can be connected to the core network 3214 via a wired or wireless connection 3215. A first user equipment (UE) 3291 (e.g., first UE 121 and / or a non-AP STA) located in coverage area 3213c is configured to wirelessly connect to or be paged by the corresponding base station 3212c. A second UE 3292 (e.g., a second UE 122 and / or a non-AP STA) in coverage area 3213a can wirelessly connect to the corresponding base station 3212a. Although multiple UEs 3291, 3292 are shown in this example, the disclosed embodiments are equally applicable to situations where a single UE is in the coverage area or a single UE is connected to the corresponding base station 3212.

[0217] Telecommunication network 3210 is connected to host computer 3230, which may be implemented as a standalone server, a cloud-based server, a distributed server, or as a processing resource in a server cluster. Host computer 3230 may be owned or controlled by a service provider, or may be operated by or on behalf of the service provider. Connections 3221 and 3222 between telecommunication network 3210 and host computer 3230 may extend directly from core network 3214 to host computer 3230, or may be made via optional intermediate network 3220. Intermediate network 3220 may be one or more of public, private, or bearer networks; intermediate network 3220 (if present) may be a backbone network or the Internet; specifically, intermediate network 3220 may include two or more subnetworks (not shown).

[0218] Figure 9 The communication system as a whole establishes a connection between one of the connected UEs 3291 and 3292 and the host computer 3230. This connection can be described as an over-the-top (OTT) connection 3250. The host computer 3230 and the connected UEs 3291 and 3292 are configured to transmit data and / or signaling via the OTT connection 3250 using access network 3211, core network 3214, any intermediate network 3220, and possibly other infrastructure (not shown) as intermediaries. The OTT connection 3250 can be transparent in the sense that the participating communication devices traversing the OTT connection 3250 are unaware of the routing of uplink and downlink communications. For example, it may not be necessary to notify the base station 3212 of the past routes of input downlink communications containing data originating from the host computer 3230 to be forwarded (e.g., handed over) to the connected UE 3291. Similarly, base station 3212 does not need to be aware of future routing of uplink communication originating from UE 3291 to host computer 3230.

[0219] Reference Figure 10This section describes example implementations of the UE, base station, and host computer discussed in the preceding paragraphs according to embodiments. In the communication system 3300, the host computer 3310 includes hardware 3315, which includes a communication interface 3316 configured to establish and maintain wired or wireless connections with interfaces of different communication devices of the communication system 3300. The host computer 3310 also includes processing circuitry 3318, which may have storage and / or processing capabilities. Specifically, the processing circuitry 3318 may include one or more programmable processors, application-specific integrated circuits, field-programmable gate arrays, or combinations thereof (not shown) suitable for executing instructions. The host computer 3310 also includes software 3311, which is stored in or accessible by the host computer 3310 and executable by the processing circuitry 3318. The software 3311 includes a host application 3312. Host application 3312 is operable to provide services to a remote user (e.g., UE 3330), which is connected via an OTT connection 3350 terminated at both UE 3330 and host computer 3310. When providing services to the remote user, host application 3312 can provide user data transmitted using the OTT connection 3350.

[0220] The communication system 3300 also includes a base station 3320 provided in the telecommunications system. The base station 3320 includes hardware 3325 enabling it to communicate with a host computer 3310 and a UE 3330. Hardware 3325 may include: a communication interface 3326 for establishing and maintaining wired or wireless connections with different communication devices of the communication system 3300; and a radio interface 3327 for establishing and maintaining connections with at least the coverage area served by the base station 3320. Figure 10 The wireless connection 3370 of UE3330 (not shown in the diagram) is provided. Communication interface 3326 can be configured to facilitate a connection 3360 to host computer 3310. Connection 3360 can be direct, or it can be via the core network of the telecommunications system (…). Figure 10 (Not shown) and / or via one or more intermediate networks outside the telecommunications system. In the illustrated embodiment, the hardware 3325 of base station 3320 also includes processing circuitry 3328, which may include one or more programmable processors, application-specific integrated circuits, field-programmable gate arrays, or combinations thereof (not shown) suitable for executing instructions. Base station 3320 also has software 3321 stored internally or accessible via an external connection.

[0221] The communication system 3300 also includes the previously mentioned UE 3330. Its hardware 3335 may include a radio interface 3337 configured to establish and maintain a wireless connection 3370 with a base station serving the coverage area currently occupied by the UE 3330. The hardware 3335 of the UE 3330 also includes processing circuitry 3338, which may include one or more programmable processors, application-specific integrated circuits, field-programmable gate arrays, or combinations thereof (not shown) suitable for executing instructions. The UE 3330 also includes software 3331, which is stored in or accessible by the UE 3330 and executable by the processing circuitry 3338. The software 3331 includes a client application 3332. The client application 3332 is operable to provide services to human or non-human users via the UE 3330 with the support of a host computer 3310. In host computer 3310, host application 3312 can communicate with client application 3332 via OTT connection 3350 terminated at UE 3330 and host computer 3310. When providing services to a user, client application 3332 can receive request data from host application 3312 and provide user data in response to the request data. OTT connection 3350 can transmit both request data and user data. Client application 3332 can interact with the user to generate the user data it provides.

[0222] Notice, Figure 10 The host computer 3310, base station 3320, and UE 3330 shown can be respectively connected to... Figure 9 The host computer 3230, base stations 3212a, 3212b, and 3212c are identical to one of the UEs 3291 and 3292. That is to say, the internal operation of these entities can be as follows: Figure 10 As shown, and independently, the surrounding network topology can be Figure 9 The network topology.

[0223] exist Figure 10 The OTT connection 3350 has been abstractly depicted to illustrate communication between the host computer 3310 and the user equipment 3330 via the base station 3320, without explicitly mentioning any intermediate devices or the precise routing of messages via these devices. The network infrastructure can determine this route, which can be configured to be hidden from the UE 3330, the service provider operating the host computer 3310, or both. During OTT connection 3350 activity, the network infrastructure can also make decisions to dynamically change the route (e.g., based on load balancing considerations or network reconfiguration).

[0224] The wireless connection 3370 between UE 3330 and base station 3320 is based on the teachings of the embodiments described throughout this disclosure. One or more embodiments in various embodiments improve the performance of OTT services provided to UE 3330 using OTT connection 3350, wherein wireless connection 3370 forms the final segment of OTT connection 3350. More precisely, the teachings of these embodiments can improve [selection of applicable RAN effects: data rate, latency, power consumption], thereby providing benefits such as [selection of applicable responsiveness to OTT services: reduced user wait time, relaxed file size limits, better responsiveness, extended battery life].

[0225] For the purpose of monitoring data rates, latency, and other factors improved in one or more embodiments, a measurement process may be provided. Optional network functions may also be available for reconfiguring the OTT connection 3350 between the host computer 3310 and the UE 3330 in response to changes in measurement results. The measurement process and / or network functions for reconfiguring the OTT connection 3350 may be implemented using software 3311 of the host computer 3310, software 3331 of the UE 3330, or both. In embodiments, sensors (not shown) may be deployed in or associated with communication equipment traversed by the OTT connection 3350; the sensors may participate in the measurement process by providing values ​​of the monitored quantities illustrated above or by providing values ​​of other physical quantities that the software 3311, 3331 can use to calculate or estimate the monitored quantities. Reconfiguration of the OTT connection 3350 may include message formatting, retransmission settings, preferred routing, etc.; this reconfiguration does not need to affect the base station 3320 and may be unknown or imperceptible to the base station 3320. Such processes and functions may be known and practiced in the art. In a particular embodiment, the measurement may involve proprietary UE signaling that facilitates the host computer 3310 in measuring throughput, propagation time, latency, etc. This measurement may be implemented by software 3311, 3331 enabling the use of OTT connection 3350 to send messages (specifically, empty messages or "fake" messages) while monitoring propagation time, errors, etc.

[0226] Figure 11 This is a flowchart illustrating a method implemented in a communication system according to one embodiment. The communication system includes a host computer, a base station (e.g., an AP STA), and a UE (e.g., a non-AP STA), which may be a reference. Figure 9 and Figure 10 The host computer, base station, and UE are described. For the sake of brevity, this section will only include descriptions of... Figure 11The diagram is referenced. In the first step 3410 of the method, the host computer provides user data. In an optional sub-step 3411 of the first step 3410, the host computer provides user data by executing a host application. In the second step 3420, the host computer initiates a transmission carrying user data to the UE. In an optional third step 3430, in accordance with the teachings of the embodiments described throughout this disclosure, the base station sends the user data carried in the transmission initiated by the host computer to the UE. In an optional fourth step 3440, the UE executes a client application associated with the host application executed by the host computer.

[0227] Figure 12 This is a flowchart illustrating a method implemented in a communication system according to one embodiment. The communication system includes a host computer, a base station (e.g., an AP STA), and a UE (e.g., a non-AP STA), which may be a reference. Figure 9 and Figure 10 The host computer, base station, and UE are described. For the sake of brevity, this section will only include descriptions of... Figure 12 The diagram is referenced. In the first step 3510 of the method, the host computer provides user data. In an optional sub-step (not shown), the host computer provides user data by executing a host application. In the second step 3520, the host computer initiates a transmission carrying user data to the UE. According to the teachings of the embodiments described throughout this disclosure, this transmission may be via a base station. In an optional third step 3530, the UE receives the user data carried in the transmission.

[0228] Figure 13 This is a flowchart illustrating a method implemented in a communication system according to one embodiment. The communication system includes a host computer, a base station (e.g., an AP STA), and a UE (e.g., a non-AP STA), which may be a reference. Figure 9 and Figure 10 The host computer, base station, and UE are described. For the sake of brevity, this section will only include descriptions of... Figure 13The diagram is referenced. In an optional first step 3610 of the method, the UE receives input data provided by the host computer. Additionally or alternatively, in an optional second step 3620, the UE provides user data. In an optional sub-step 3621 of the second step 3620, the UE provides user data by executing a client application. In another optional sub-step 3611 of the first step 3610, the UE executes a client application that provides user data in response to the received input data provided by the host computer. When providing user data, the executed client application may also consider user input received from the user. Regardless of the specific manner in which user data is provided, the UE initiates the transmission of user data to the host computer in an optional third sub-step 3630. In a fourth step 3640 of the method, the host computer receives user data sent from the UE, in accordance with the teachings of the embodiments described throughout this disclosure.

[0229] Figure 14 This is a flowchart illustrating a method implemented in a communication system according to one embodiment. The communication system includes a host computer, a base station (e.g., an AP STA), and a UE (e.g., a non-AP STA), which may be a reference. Figure 9 and Figure 10 The host computer, base station, and UE are described. For the sake of brevity, this section will only include descriptions of... Figure 14 The diagram is referenced. In an optional first step 3710 of the method, the base station receives user data from the UE in accordance with the teachings of the embodiments described throughout this disclosure. In an optional second step 3720, the base station initiates a transmission of the received user data to a host computer. In a third step 3730, the host computer receives the user data carried in the transmission initiated by the base station.

[0230] When the words “include” or “contain” are used, they should be interpreted as non-restrictive, meaning “consisting of at least…”.

[0231] The embodiments described herein are not limited to the preferred embodiments described above. Various alternatives, modifications, and equivalents may be used.

Claims

1. A method executed by a first IMS node for processing the establishment of a session for communication with a user equipment (UE) in a communication network, wherein, The UE is assigned a first server for session control of the session, and the method includes: A request is sent to the subscriber server associated with the UE, the request requesting the selection of a second server to be assigned to the UE for auxiliary data used in the session control. When the requested auxiliary data is received from the subscriber server, a second server is selected and assigned to the UE for session control based on the requested auxiliary data. An invitation is sent to the selected second server, the invitation relating to the establishment of the session, the invitation including an indication that the selected second server is chosen to replace the first server assigned to the UE for session control, and The instruction triggers the selected second server to instruct the subscriber server to register the address of the selected second server in the subscriber server, in order to replace the first server being assigned to the UE for the session control. The instruction allows the subscriber server to perform the registration so that a selected second server can be assigned to the UE for session control of the session, instead of the first server.

2. The method according to claim 1, wherein, The indication is included in the routing header of the invitation, and / or The invitation is a Session Initiation Protocol (SIP) request message.

3. The method according to claim 1, wherein, The request is any one or more of the following: HTTP GET request, and Diameter request message.

4. The method according to claim 1, wherein, The request is sent if any of the following occurs: - The first IMS node determines that the first server was unavailable when the session was established, or - It is determined that the first server will be replaced when the session is established.

5. The method according to claim 1, further comprising: The endpoint receives an invitation request, which includes an invitation related to establishing a session for communication with the UE, and... The invitation is sent to the first server assigned to the UE.

6. A computer program product comprising instructions that, when executed by a processor, cause the processor to perform the action according to any one of claims 1 to 5.

7. A computer-readable storage medium having a computer program stored thereon, the computer program implementing the method according to any one of claims 1 to 5 when executed by a processor.

8. A method executed by a second server for processing the establishment of a session for communication with a user equipment (UE) in a communication network, wherein, The UE is assigned a first server for session control of the session, and the method includes: Receive an invitation from the first IMS node, the invitation being related to establishing the session. The invitation includes an indication that the second server is selected to replace the first server assigned to the UE for session control, and Triggered by the indication, a registration request is sent to the subscriber server associated with the UE, the registration request including the indication, and The registration request requests the subscriber server to register the address of the selected second server with the subscriber server, so that the first server is assigned to the UE for the session control. The instruction allows the subscriber server to perform the registration so that a selected second server can be assigned to the UE for session control of the session, instead of the first server.

9. The method according to claim 8, wherein, The indication is included in the routing header of the invitation, and / or The invitation is a Session Initiation Protocol (SIP) request message.

10. The method according to claim 8, wherein, The registration request is any one or more of the following: The Hypertext Transfer Protocol (HTTP) PUT request, and Diameter request message.

11. The method according to claim 8, wherein, The invitation from the first IMS node is received if any of the following occurs: - The first IMS node determines that the first server was unavailable when the session was established, or - It has been decided that the first server will be replaced when the session is established.

12. A computer program product comprising instructions that, when executed by a processor, cause the processor to perform the action according to any one of claims 8 to 11.

13. A computer-readable storage medium having a computer program stored thereon, the computer program implementing the method according to any one of claims 8 to 11 when executed by a processor.

14. A method performed by a subscriber server for processing the establishment of a session for communication with a user equipment (UE) in a communication network, wherein, The UE is assigned a first server for session control of the session, and the subscriber server is associated with the UE, the method comprising: A request is received from a first IMS node associated with the UE, the request requesting the selection of a second server to be assigned to the UE for auxiliary data used in the session control. Send the requested auxiliary data to the first IMS node. The subscriber server receives a registration request from the second server, the registration request including an indication that the second server has been selected based on the auxiliary data to replace the first server assigned to the UE for session control, the registration request request including the indication, and allowing the subscriber server to register the address of the selected second server with the subscriber server, in place of the first server assigned to the UE for session control. Based on the registration request including the indicated information, the registration is performed to assign the selected second server to the UE for session control of the session.

15. The method according to claim 14, wherein, The registration request is any one or more of the following: The Hypertext Transfer Protocol (HTTP) PUT request, and Diameter request message.

16. The method of claim 14, wherein, The request is any one or more of the following: HTTP GET request, and Diameter request message.

17. The method of claim 14, wherein, The request is received if any of the following occurs: - The first IMS node determines that the first server was unavailable when the session was established, or - It is determined that the first server will be replaced when the session is established.

18. A computer program product comprising instructions that, when executed by a processor, cause the processor to perform the action according to any one of claims 14 to 16.

19. A computer-readable storage medium having a computer program stored thereon, the computer program implementing the method according to any one of claims 14 to 16 when executed by a processor.

20. A first IMS node configured to handle the establishment of a session for communicating with a user equipment (UE) in a communication network, wherein, The UE is adapted to be assigned a first server for session control of the session, wherein the first IMS node includes: processor, Memory, storing instructions, wherein, when executed by the processor, the instructions cause the first IMS node to: A request is sent to a subscriber server suitable for association with the UE, the request being adapted to request auxiliary data for selecting a second server to be assigned to the UE for the session control. When the requested auxiliary data is received from the subscriber server, a second server is selected and assigned to the UE for session control based on the requested auxiliary data. An invitation is sent to the selected second server, the invitation being adapted to relate to establishing the session, and the invitation is further adapted to include an indication suitable for indicating that the selected second server is chosen to replace the first server assigned to the UE for session control, and The instruction is also adapted to trigger the selected second server to instruct the subscriber server to register the address of the selected second server in the subscriber server, in place of the first server being assigned to the UE for the session control. The instruction is also adapted to allow the subscriber server to perform the registration so that a selected second server is assigned to the UE for session control of the session instead of the first server.

21. The first IMS node according to claim 20, wherein, The indication is also adapted to be included in the routing header of the invitation, and / or The invitation is also suitable as a Session Initiation Protocol (SIP) request message.

22. The first IMS node according to claim 20, wherein, The request is also suitable to be any one or more of the following: HTTP GET request, and Diameter request message.

23. The first IMS node according to claim 20, wherein, The request is also suitable to be sent if any of the following occurs: - The first IMS node determines that the first server was unavailable when the session was established, or - It is determined that the first server will be replaced when the session is established.

24. The first IMS node according to claim 20, wherein, The instruction also causes the first IMS node to: An invitation request is received from the end node of the calling UE, the invitation request being adapted to include an invitation related to establishing the session for communication with the UE, and The invitation is sent to the first server suitable for being assigned to the UE.

25. A second server configured to handle the establishment of sessions for communicating with a user equipment (UE) in a communication network, wherein, The UE is adapted to be assigned a first server for session control of the session, wherein the second server includes: processor, Memory, storing instructions, wherein the instructions, when executed by the processor, cause the second server to: Receive an invitation from the first IMS node, the invitation being appropriate for establishing the session. The invitation is also adapted to include an indication that the second server is selected to replace the first server assigned to the UE for session control, and Triggered by the indication, a registration request is sent to a subscriber server suitable for association with the UE, the registration request being adapted to include the indication, and The registration request is also adapted to request the subscriber server to register the address of the selected second server with the subscriber server, in order to replace the first server being assigned to the UE for the session control. The instruction is adapted to allow the subscriber server to perform the registration so that a selected second server is assigned to the UE for session control of the session, instead of the first server.

26. The second server according to claim 25, wherein, The indication is also adapted to be included in the routing header of the invitation, and / or The invitation is also suitable as a Session Initiation Protocol (SIP) request message.

27. The second server according to claim 25, wherein, The registration request may also be any one or more of the following: The Hypertext Transfer Protocol (HTTP) PUT request, and Diameter request message.

28. The second server according to claim 25, wherein, The invitation from the first IMS node is also suitable to be received if any of the following occurs: - The first IMS node determines that the first server was unavailable when the session was established, or - It has been decided that the first server will be replaced when the session is established.

29. A subscriber server configured to handle the establishment of sessions for communication with a user equipment (UE) in a communication network, wherein, The UE is adapted to be assigned a first server for session control of the session, and wherein the subscriber server is adapted to be associated with the UE, wherein the subscriber server includes: processor, Memory, storing instructions, wherein, when executed by the processor, the instructions cause the subscriber server to: A request is received from a first IMS node adapted to be associated with the UE, the request being adapted to request the selection of a second server to be assigned to the UE for auxiliary data used in the session control. Send the requested auxiliary data to the first IMS node. The registration request is received from the second server, the registration request being adapted to include an indication that the second server has been selected based on the auxiliary data to replace the first server assigned to the UE for session control. The registration request, including the indication, is further adapted to request and allow the subscriber server to register the address of the selected second server with the subscriber server, in place of the first server assigned to the UE for session control. Based on the registration request including the indicated information, the registration is performed to assign the selected second server to the UE for session control of the session.

30. The subscriber server according to claim 29, wherein, The registration request may also be any one or more of the following: The Hypertext Transfer Protocol (HTTP) PUT request, and Diameter request message.

31. The subscriber server according to claim 29, wherein, The request is also suitable to be any one or more of the following: HTTP GET request, and Diameter request message.

32. The subscriber server according to claim 29, wherein, The request is also suitable to be received if any of the following occurs: - The first IMS node determines that the first server was unavailable when the session was established, or - It is determined that the first server will be replaced when the session is established.

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