Apparatus, method, and computer program for inter-radio access technology mobility event

Abstract

The disclosure relates to a method comprising: receiving, from an access and mobility management function in the communication system, a request to deactivate a user equipment at the short message service function, wherein the request to deactivate the user equipment at the short message service function comprises a cause for deactivating the user equipment at the short message service function; and based on the cause for deactivating the user equipment at the short message service function: transmitting, to a unified data management in the communication system, a request to deregister the short message service function at the unified data management and deleting a user equipment context for the user equipment; or marking a user equipment context for the user equipment as inactive.

Description

APPARATUS, METHOD, AND COMPUTER PROGRAM FOR INTER-RADIO ACCESS TECHNOLOGY MOBILITY EVENTRelated Applications

[0001] This patent application claims the benefit of priority of Indian Provisional Patent Application No. 202341089931 filed December 29, 2023, which is hereby incorporated by reference as if reproduced in its entirety.Field of the disclosure

[0002] The present disclosure relates to a method, an apparatus and a computer program for a short message service function, an access and mobility management function or a unified data management, in particular when a user equipment switches from a communication system to another communication system.Background

[0003] A communication system can be seen as a facility that enables communication sessions between two or more entities such as communication devices, base stations and / or other nodes by providing carriers between the various entities involved in the communications path.

[0004] The communication system and associated entities typically operate in accordance with a given standard or specification which sets out what the associated entities are permitted to do and how that should be achieved. Communication protocols and / or parameters which shall be used for the connection are also typically defined. Examples of standard are the so-called 5G standards.Summary

[0005] According to an aspect there is provided a method comprising: receiving, from an access and mobility management function in the communication system, a request to deactivate a user equipment at the short message service function, wherein the request to deactivate the user equipment at the short message service function comprises a cause for deactivating the user equipment at the short message service function; and based on the cause for deactivating the user equipment at the short message service function: transmitting, to a unified data management in the communication system, a request to deregister the short message service function at the unified data management and deleting a user equipment context for the user equipment; or marking a user equipment context for the user equipment as inactive, wherein deregistering the short message service function at the unified data management comprises deleting at least one of an identity of the shortmessage service function or an address of the short message service function stored at the unified data management.

[0006] The short message service function may transmit, to the unified data management, the request to deregister the short message service function at the unified data management conditionally to reduce signalling overhead between the short message service function and the unified data management.

[0007] The method may comprise: determining that the cause for deactivating the user equipment at the short message service function indicates that the user equipment has switched from the communication system to another communication system; determining, based on the cause for deactivating the user equipment at the short message service function, to abstain from transmitting, to the unified data management in the communication system, the request to deregister the short message service function at the unified data management and mark a user equipment context for the user equipment as inactive; and marking the user equipment context for a user equipment as inactive.

[0008] The communication system may use a radio access technology and the other communication system may use a different radio access technology.

[0009] The communication system may be a 5G system and the other communication system may be an evolved packet system.

[0010] The method may comprise: determining, based on the cause for deactivating the user equipment at the short message service function, to abstain from transmitting, to the unified data management, a request to unsubscribe to a subscription data management service provided at the unified data management and mark a user equipment context for the user equipment as inactive; and marking the user equipment context for the user equipment as inactive.

[0011] The method may comprise: determining that a timer associated with the user equipment context for the user equipment has expired; and deleting the user equipment context for the user equipment.

[0012] The method may comprise: receiving, from the access and mobility management function, a request to activate the user equipment at the short message service function; determining that the user equipment context for the user equipment is marked as inactive; and determining, based on the user equipment context for the user equipment being marked as inactive, to abstain from transmitting, to the unified data management, a request to register the short message service function at the unified data management.

[0013] The method may comprise: determining, based on the user equipment context for the user equipment being marked as inactive, to abstain from transmitting, to the unified data management, a request to get a subscription data management service provided at the unified data management.

[0014] The method may comprise: determining, based on the context for the user equipment being marked as inactive, to abstain from transmitting, to the unified data management, a request to subscribe to a subscription data management service provided at the unified data management.

[0015] The method may comprise: marking the user equipment context for the user equipment as enabled.

[0016] The method may comprise: determining that the cause for deactivating the user equipment at the short message service function does not indicate that the user equipment has switched from the communication system to another communication system; determining, based on the cause for deactivating the user equipment at the short message service function, to transmit, to the unified data management, the request to deregister the short message service function at the unified data management and to delete a user equipment context for the user equipment; transmitting, to the unified data management, the request to deregister the short message service function at the unified data management; and deleting the user equipment context for the user equipment.

[0017] The cause for deactivating the user equipment at the short message service function may indicate that: the user equipment does not have a short message service subscription; the user equipment is switched off; or the user equipment is out of the coverage of the communication system.

[0018] The method may comprise: receiving, from the access and mobility management function, a request to activate the user equipment at the short message service function; determining, based on the context for the user equipment being deleted, to transmit, to the unified data management, a request to register the short message service function at the unified data management; and transmitting, to the unified data management, a request to register the short message service function at the unified data management.

[0019] The method may comprise: determining, based on the context for the user equipment being deleted, to transmit, to the unified data management, a request to get a subscription data management service provided at the unified data management; and transmitting, to the unified data management, a request to get a subscription data management service provided at the unified data management.

[0020] The method may comprise: determining, based on the context for the user equipment being deleted, to transmit, to the unified data management, a request tosubscribe to a subscription data management service provided at the unified data management; and transmitting, to the unified data management, a request to subscribe to a subscription data management service provided at the unified data management.

[0021] The cause for deactivating the user equipment at the short message service function may be conveyed as: a query parameter in the request to deactivate the user equipment at the short message service function; an information element of a javascript object notation body in the request to deactivate the user equipment at the short message service function; or a header in the request to deactivate the user equipment at the short message service function.

[0022] The user equipment context for the user equipment may be stored at the short message service function or at an unstructured data storage function.

[0023] The short message service function may serve a user equipment in single registration mode.

[0024] The short message service function may serve the user equipment for 3GPP access or non- 3GPP access.

[0025] According to an aspect there is provided an apparatus comprising means for: receiving, from an access and mobility management function in the communication system, a request to deactivate a user equipment at the short message service function, wherein the request to deactivate the user equipment at the short message service function comprises a cause for deactivating the user equipment at the short message service function; and based on the cause for deactivating the user equipment at the short message service function: transmitting, to a unified data management in the communication system, a request to deregister the short message service function at the unified data management and deleting a user equipment context for the user equipment; or marking a user equipment context for the user equipment as inactive, wherein deregistering the short message service function at the unified data management comprises deleting at least one of an identity of the short message service function or an address of the short message service function stored at the unified data management.

[0026] The short message service function may transmit, to the unified data management, the request to deregister the short message service function at the unified data management conditionally to reduce signalling overhead between the short message service function and the unified data management.

[0027] The apparatus may comprise means for: determining that the cause for deactivating the user equipment at the short message service function indicates that the user equipment has switched from the communication system to another communication system; determining, based on the cause for deactivating the user equipment at the short messageservice function, to abstain from transmitting, to the unified data management in the communication system, the request to deregister the short message service function at the unified data management and mark a user equipment context for the user equipment as inactive; and marking the user equipment context for a user equipment as inactive.

[0028] The communication system may use a radio access technology and the other communication system may use a different radio access technology.

[0029] The communication system may be a 5G system and the other communication system may be an evolved packet system.

[0030] The apparatus may comprise means for: determining, based on the cause for deactivating the user equipment at the short message service function, to abstain from transmitting, to the unified data management, a request to unsubscribe to a subscription data management service provided at the unified data management and mark a user equipment context for the user equipment as inactive; and marking the user equipment context for the user equipment as inactive.

[0031] The apparatus may comprise means for: determining that a timer associated with the user equipment context for the user equipment has expired; and deleting the user equipment context for the user equipment.

[0032] The apparatus may comprise means for: receiving, from the access and mobility management function, a request to activate the user equipment at the short message service function; determining that the user equipment context for the user equipment is marked as inactive; and determining, based on the user equipment context for the user equipment being marked as inactive, to abstain from transmitting, to the unified data management, a request to register the short message service function at the unified data management.

[0033] The apparatus may comprise means for: determining, based on the user equipment context for the user equipment being marked as inactive, to abstain from transmitting, to the unified data management, a request to get a subscription data management service provided at the unified data management.

[0034] The apparatus may comprise means for: determining, based on the context for the user equipment being marked as inactive, to abstain from transmitting, to the unified data management, a request to subscribe to a subscription data management service provided at the unified data management.

[0035] The apparatus may comprise means for: marking the user equipment context for the user equipment as enabled.

[0036] The apparatus may comprise means for: determining that the cause for deactivating the user equipment at the short message service function does not indicate that the user equipment has switched from the communication system to another communication system; determining, based on the cause for deactivating the user equipment at the short message service function, to transmit, to the unified data management, the request to deregister the short message service function at the unified data management and to delete a user equipment context for the user equipment; transmitting, to the unified data management, the request to deregister the short message service function at the unified data management; and deleting the user equipment context for the user equipment.

[0037] The cause for deactivating the user equipment at the short message service function may indicate that: the user equipment does not have a short message service subscription; the user equipment is switched off; or the user equipment is out of the coverage of the communication system.

[0038] The apparatus may comprise means for: receiving, from the access and mobility management function, a request to activate the user equipment at the short message service function; determining, based on the context for the user equipment being deleted, to transmit, to the unified data management, a request to register the short message service function at the unified data management; and transmitting, to the unified data management, a request to register the short message service function at the unified data management.

[0039] The apparatus may comprise means for: determining, based on the context for the user equipment being deleted, to transmit, to the unified data management, a request to get a subscription data management service provided at the unified data management; and transmitting, to the unified data management, a request to get a subscription data management service provided at the unified data management.

[0040] The apparatus may comprise means for: determining, based on the context for the user equipment being deleted, to transmit, to the unified data management, a request to subscribe to a subscription data management service provided at the unified data management; and transmitting, to the unified data management, a request to subscribe to a subscription data management service provided at the unified data management.

[0041] The cause for deactivating the user equipment at the short message service function may be conveyed as: a query parameter in the request to deactivate the user equipment at the short message service function; an information element of a javascript object notation body in the request to deactivate the user equipment at the short message service function; or a header in the request to deactivate the user equipment at the short message service function.

[0042] The user equipment context for the user equipment may be stored at the short message service function or at an unstructured data storage function.

[0043] The short message service function may serve a user equipment in single registration mode.

[0044] The short message service function may serve the user equipment for 3GPP access or non-cellula3GPP access.

[0045] According to an aspect there is provided an apparatus comprising circuitry configured to: receive, from an access and mobility management function in the communication system, a request to deactivate a user equipment at the short message service function, wherein the request to deactivate the user equipment at the short message service function comprises a cause for deactivating the user equipment at the short message service function; and based on the cause for deactivating the user equipment at the short message service function: transmit, to a unified data management in the communication system, a request to deregister the short message service function at the unified data management and delete a user equipment context for the user equipment; or mark a user equipment context for the user equipment as inactive, wherein deregistering the short message service function at the unified data management comprises deleting at least one of an identity of the short message service function or an address of the short message service function stored at the unified data management.

[0046] According to an aspect there is provided an apparatus comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive, from an access and mobility management function in the communication system, a request to deactivate a user equipment at the short message service function, wherein the request to deactivate the user equipment at the short message service function comprises a cause for deactivating the user equipment at the short message service function; and based on the cause for deactivating the user equipment at the short message service function: transmit, to a unified data management in the communication system, a request to deregister the short message service function at the unified data management and delete a user equipment context for the user equipment; or mark a user equipment context for the user equipment as inactive, wherein deregistering the short message service function at the unified data management comprises deleting at least one of an identity of the short message service function or an address of the short message service function stored at the unified data management.

[0047] According to an aspect there is provided a computer program comprising computer executable code which when run on at least one processor is configured to: receive, from an access and mobility management function in the communication system, a request to deactivate a user equipment at the short message service function, wherein the request to deactivate the user equipment at the short message service function comprises a cause for deactivating the user equipment at the short message service function; and based on the cause for deactivating the user equipment at the short message service function: transmit, to a unified data management in the communication system, a request to deregister the short message service function at the unified data management and delete a user equipment context for the user equipment; or mark a user equipment context for the user equipment as inactive, wherein deregistering the short message service function at the unified data management comprises deleting at least one of an identity of the short message service function or an address of the short message service function stored at the unified data management.

[0048] According to an aspect there is provided a method comprising: receiving, from a unified data management in the communication system, a notification to deregister a user equipment at the access and mobility management function, wherein the notification comprises a cause for deregistering the user equipment at the access and mobility management function; and transmitting a request to deactivate the user equipment at a short message service function in the communication system, wherein the request to deactivate the user equipment at the short message service function comprises a cause for deactivating the user equipment at the short message service function, wherein the cause for deactivating the user equipment at the short message service function is based on the cause for deregistering the user equipment at the access and mobility management function.

[0049] At least one of the cause for deactivating the user equipment at the short message service function or the cause for deregistering the user equipment at the access and mobility management function may indicate that: the user equipment switches from the communication system to another communication system; the use equipment does not have a short message service subscription; the user equipment is switched off; or the user equipment is out of the coverage of the communication system.

[0050] According to an aspect there is provided an apparatus comprising means for: receiving, from a unified data management in the communication system, a notification to deregister a user equipment at the access and mobility management function, wherein the notification comprises a cause for deregistering the user equipment at the access and mobility management function; and transmitting a request to deactivate the user equipmentat a short message service function in the communication system, wherein the request to deactivate the user equipment at the short message service function comprises a cause for deactivating the user equipment at the short message service function, wherein the cause for deactivating the user equipment at the short message service function is based on the cause for deregistering the user equipment at the access and mobility management function.

[0051] At least one of the cause for deactivating the user equipment at the short message service function or the cause for deregistering the user equipment at the access and mobility management function may indicate that: the user equipment switches from the communication system to another communication system; the use equipment does not have a short message service subscription; the user equipment is switched off; or the user equipment is out of the coverage of the communication system.

[0052] According to an aspect there is provided an apparatus comprising circuitry configured to: receive, from a unified data management in the communication system, a notification to deregister a user equipment at the access and mobility management function, wherein the notification comprises a cause for deregistering the user equipment at the access and mobility management function; and transmit a request to deactivate the user equipment at a short message service function in the communication system, wherein the request to deactivate the user equipment at the short message service function comprises a cause for deactivating the user equipment at the short message service function, wherein the cause for deactivating the user equipment at the short message service function is based on the cause for deregistering the user equipment at the access and mobility management function.

[0053] According to an aspect there is provided an apparatus comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive, from a unified data management in the communication system, a notification to deregister a user equipment at the access and mobility management function, wherein the notification comprises a cause for deregistering the user equipment at the access and mobility management function; and transmit a request to deactivate the user equipment at a short message service function in the communication system, wherein the request to deactivate the user equipment at the short message service function comprises a cause for deactivating the user equipment at the short message service function, wherein the cause for deactivating the user equipment at the short message service function is based on the cause for deregistering the user equipment at the access and mobility management function.

[0054] According to an aspect there is provided a computer program comprising computer executable code which when run on at least one processor is configured to: receive, from a unified data management in the communication system, a notification to deregister a user equipment at the access and mobility management function, wherein the notification comprises a cause for deregistering the user equipment at the access and mobility management function; and transmit a request to deactivate the user equipment at a short message service function in the communication system, wherein the request to deactivate the user equipment at the short message service function comprises a cause for deactivating the user equipment at the short message service function, wherein the cause for deactivating the user equipment at the short message service function is based on the cause for deregistering the user equipment at the access and mobility management function.

[0055] According to an aspect there is provided a method comprising: receiving, from a short message service centre or an internet protocol short message gateway, a request to retrieve at least one of an identity of a short message service function in the communication system or an address of a short message service function in the communication system; receiving, from a home subscriber server in another communication system, an indication that a user equipment has switched from the communication system to the other communication system; and based on the indication that a user equipment has switched from the communication system to the other communication system transmitting at least one alternative identity or alternative address or transmitting a message indicating an error.

[0056] The method may comprise: determining, based on the indication that a user equipment has switched from the communication system to the other communication system, to abstain from transmitting to the short message service centre or the internet protocol short message gateway, at least one of the identity of the short message service function or the address of the short message service function and transmit, to the short message service centre, at least one alternative identity or alternative address.

[0057] The alternative identity may comprise the identity of an internet protocol short message gateway, a mobility management entity, a serving general packet radio service support node or a mobile switching centre; or the alternative address may comprise the address of an internet protocol short message gateway, a mobility management entity, a serving general packet radio service support node or a mobile switching centre.

[0058] According to an aspect there is provided an apparatus comprising means for: receiving, from a short message service centre or an internet protocol short message gateway, a request to retrieve at least one of an identity of a short message service function in the communication system or an address of a short message service function in thecommunication system; receiving, from a home subscriber server in another communication system, an indication that a user equipment has switched from the communication system to the other communication system; and based on the indication that a user equipment has switched from the communication system to the other communication system transmitting at least one alternative identity or alternative address or transmitting a message indicating an error.

[0059] The apparatus may comprise means for: determining, based on the indication that a user equipment has switched from the communication system to the other communication system, to abstain from transmitting to the short message service centre or the internet protocol short message gateway, at least one of the identity of the short message service function or the address of the short message service function and transmit, to the short message service centre, at least one alternative identity or alternative address.

[0060] The alternative identity may comprise the identity of an internet protocol short message gateway, a mobility management entity, a serving general packet radio service support node or a mobile switching centre; or the alternative address may comprise the address of an internet protocol short message gateway, a mobility management entity, a serving general packet radio service support node or a mobile switching centre.

[0061] According to an aspect there is provided an apparatus comprising circuitry configured to: receive, from a short message service centre or an internet protocol short message gateway, a request to retrieve at least one of an identity of a short message service function in the communication system or an address of a short message service function in the communication system; receive, from a home subscriber server in another communication system, an indication that a user equipment has switched from the communication system to the other communication system; and based on the indication that a user equipment has switched from the communication system to the other communication system transmit at least one alternative identity or alternative address or transmit a message indicating an error.

[0062] According to an aspect there is provided an apparatus comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive, from a short message service centre or an internet protocol short message gateway, a request to retrieve at least one of an identity of a short message service function in the communication system or an address of a short message service function in the communication system; receive, from a home subscriber server in another communication system, an indication that a user equipment has switched from the communication system to the other communication system; and based on the indication that a user equipment has switched from the communication systemto the other communication system transmit at least one alternative identity or alternative address or transmit a message indicating an error.

[0063] According to an aspect there is provided a computer program comprising computer executable code which when run on at least one processor is configured to: receive, from a short message service centre or an internet protocol short message gateway, a request to retrieve at least one of an identity of a short message service function in the communication system or an address of a short message service function in the communication system; receive, from a home subscriber server in another communication system, an indication that a user equipment has switched from the communication system to the other communication system; and based on the indication that a user equipment has switched from the communication system to the other communication system transmit at least one alternative identity or alternative address or transmit a message indicating an error.

[0064] According to an aspect, there is provided a computer readable medium comprising program instructions stored thereon for performing at least one of the above methods.

[0065] According to an aspect, there is provided a non-transitory computer readable medium comprising program instructions stored thereon for performing at least one of the above methods.

[0066] According to an aspect, there is provided a non-volatile tangible memory medium comprising program instructions stored thereon for performing at least one of the above methods.

[0067] In the above, many different aspects have been described. It should be appreciated that further aspects may be provided by the combination of any two or more of the aspects described above.

[0068] Various other aspects are also described in the following detailed description and in the attached claims.List of abbreviations

[0069] AF: Application Function

[0070] AMF: Access and Mobility Management Function

[0071] AUSF: Authentication Server Function

[0072] BS: Base Station

[0073] CU: Centralized Unit

[0074] DU: Distributed Unit

[0075] EPC: Evolved Packet Core

[0076] EPS: Evolved Packet System

[0077] E-UTRAN: Evolved Universal Terrestrial Radio Access Network

[0078] gNB: gNodeB

[0079] HSS: Home Subscriber Server

[0080] HTTP: HyperText Transfer Protocol

[0081] IE: Information Element

[0082] IMS: Internet Protocol Multimedia Subsystem

[0083] loT: Internet of Things

[0084] IP-SM-GW: Internet Protocol Short Message Gateway

[0085] iRAT: Inter-Radio Access Technology

[0086] JSON: Javascript Object Notation

[0087] LMF: Location Management Function

[0088] LTE: Long Term Evolution

[0089] MAC: Medium Access Control

[0090] MME: Mobility Management Entity

[0091] MS: Mobile Station

[0092] MSC: Mobile Switching Centre

[0093] MTC: Machine Type Communication

[0094] NEF: Network Exposure Function

[0095] NF: Network Function

[0096] NR: New radio

[0097] NRF: Network Repository Function

[0098] PDU: Packet Data Unit

[0099] RAM: Random Access Memory

[0100] RAN: (Radio) Access Network

[0101] ROM: Read Only Memory

[0102] SC: Service Centre

[0103] SDM: Subscriber Data Management

[0104] SMS: Short Message Service

[0105] SMSC: Short Message Service Centre

[0106] SMSF: Short Message Service Function

[0107] SMS-GMSC Short Message Service Gateway Mobile Switching Centre

[0108] SMS-SC: Short Message Service Service Centre

[0109] SRIForSM: Sending Routing Information for Short Message

[0110] TS: Technical Specification

[0111] UDM: Unified Data Management

[0112] UDR: Unified Data Repository

[0113] UDSF: Unstructured Data Storage Function

[0114] UE: User Equipment

[0115] UPF: User Plane Function

[0116] 2G: 2ndGeneration

[0117] 2GC: 2G Core network

[0118] 2GS: 2G System

[0119] 3G: 3rdGeneration

[0120] 3GC: 3G Core network

[0121] 3GPP: 3rdGeneration Partnership Project

[0122] 3GS: 3G System

[0123] 4G: 4thGeneration

[0124] 4GC: 4G Core network

[0125] 4GS: 4G System

[0126] 5G: 5thGeneration

[0127] 5GC: 5G Core network

[0128] 5GS: 5G SystemBrief Description of the Figures

[0129] Embodiments will now be described, by way of example only, with reference to the accompanying Figures in which:

[0130] Fig 1 shows a schematic representation of a deployment comprising a 2G system / 3G system , an evolved packet system, an Internet protocol multimedia subsystem and a 5G system;

[0131] Fig. 2 shows a schematic representation of a control apparatus;

[0132] Fig. 3 shows a schematic representation of a user equipment;

[0133] Fig. 4 shows a schematic representation of a call flow of a process for determining whether to transmit, to a unified data management, a request to deregister a short message service function at the unified data management;

[0134] Fig. 5 shows a schematic representation of a call flow of a process for determining whether to transmit, to a short message service centre, at least one of an identity of a short message service function or an address of a short message service function;

[0135] Fig. 6 shows a schematic representation of a call flow of a process for determining to abstain from transmitting to a short message service centre, at least one of an identity of a short message service function or an address of a short message service function;

[0136] Fig. 7 shows a schematic representation of a call flow of a process for deleting a context of a user equipment stored at a short message service function;

[0137] Fig. 8 shows a schematic representation of a flowchart of a method for a short message service function of a communication system;

[0138] Fig 9 shows a schematic representation of a block diagram of a method an access and mobility management function in a communication system;

[0139] Fig. 10 shows a schematic representation of a block diagram of a method for a unified data management in a communication system; and

[0140] Fig. 11 shows a schematic representation of a non-volatile memory medium storing instructions which when executed by a processor allow a processor to perform one or more of the steps of the methods of Fig.8 to Fig. 10.Detailed Description of the Figures

[0141] In the following certain embodiments are explained with reference to communication devices capable of communication via a wireless communication system (e.g., a cellular system or a mobile communication system) serving such communication devices. Before explaining in detail the exemplifying embodiments, certain general principles of a wireless communication system, access systems thereof, and communication devices are briefly explained with reference to Fig. 1 , Fig. 2 and Fig .3 to assist in understanding the technology underlying the described examples. In the following description, the terms communication device and user equipment may be interchanged.

[0142] FIG. 1 shows a schematic representation of a deployment comprising a 2G system / 3G system (2GS / 3GS), an evolved packet system (EPS), an Internet protocol multimedia subsystem (IMS) and a 5G system (5GS).

[0143] The 2GS / 3GS may comprise a 2G radio access network (2G RAN) / 3G (radio) access network (3G RAN) (not represented) and a 2G core network (2GC) / 3G core network (3GC). The 2GC / 3GC may comprise a mobile switching centre (MSG) and a short message service centre (SMSC)centre.

[0144] In this disclosure, the expressions short message service centre (SMSC), service centre (SC), short message service gateway mobile switching centre (SMS-GMSC), servicecentre gateway mobile switching centre (SC-GMSC) or short message service service centre (SMS-SC may be used interchangeably.

[0145] The EPS may comprise an evolved universal terrestrial (radio) access network (E- LITRAN) (not represented) and an evolved packet core (EPC). The EPC may comprise a mobility management entity (MME) and a home subscriber function (HSS).

[0146] In this disclosure the EPS may also be referred to as a 4G system (4GS), the E- LITRAN may also be referred to as 4G radio access network (4G RAN) and the EPC may also be referred to as 4G core network (4GC).

[0147] The IMS may comprise an internet protocol short message gateway (IP-SM-GW).

[0148] The 5GS may comprise user equipment (UE), a wireless access network comprising a 5G (radio) access network (RAN), and 5G core network (5GC). The 5GS may be connected to or more application functions (AF) hosted on one or more application servers and and one or more data networks (DN).

[0149] The 5G RAN may comprise one or more base stations. A base station (otherwise referred to as a RAN node) may be an evolved NodeB (eNB) or a gNodeB (gNB). A gNB may comprise distributed units connected to one or more centralized units.

[0150] The 5GC may comprise a unified data repository (UDR), a network exposure function (NEF), a network repository function (NRF), a user data management (UDM), a short message service function (SMSF), an unstructured data storage function (LIDSF), an access and mobility management function (AMF), an authentication server function (ALISF), a session management function (SMF), a user plane function (UPF).

[0151] Fig. 2 illustrates an example of an apparatus 200 comprising or implementing one or more network functions of the 5GC illustrated in Fig. 1. The apparatus 200 may comprise at least one random access memory (RAM) 211a, at least on read only memory (ROM) 211 b, at least one processor 212, 213 and an input / output interface 214. The at least one processor 212, 213 may be coupled to the RAM 211a and the ROM 211 b. The software code 215 may be stored in the ROM 211 b. The software code 214 stored by the ROM 211b may comprise software code of a SMSF, software code of an AMF, and / or software code of a UDM function. The at least one processor 212, 213 may be configured to execute the software code 215 (e.g., the instructions of the software code 215). For example, when the software code 215 comprises software code of a SMSF, execution of the software code of the SMSF (e.g., instructions of the SMSF) by the at least one processor causes the apparatus 200 perform the method of FIG. 8 described below. When the software code 215 comprises software code of an AMF, execution of the software code of the AMF (e.g.,instructions of the AMF) by the at least one processor causes the apparatus 200 perform the method of FIG. 9 described below. When the software code 215 comprises software code of a UDM function, execution of the software code of the UDM function (e.g., instructions of the UDM function) by the at least one processor causes the apparatus 200 perform the method of FIG. 10 described below The apparatus 200 may be interconnected with another apparatus 200 comprising or implementing one or more network functions of the 5GC illustrated in FIG. 1. In some embodiments, the apparatus 200 may comprise a computing device, such server or a virtual machine. In some embodiments, the apparatus 200 may comprise a computing system, such as a distributed computing system or a cloud computing system comprising one or more virtual machines or containers implementing one or more network functions, including the SMSF, AMF, and / or the UDM entity of the 5GC illustrated in FIG. 1. apparatus 200 may comprise a cloud native core network comprising one or more of the network functions, including the SMSF, AMF, and / or the UDM entity of the 5GC illustrated in FIG. 1.

[0152] Fig. 3 illustrates an example of a UE 300, such as the UE illustrated on Fig. 1. The UE 300 is a communication device that is capable of (or configured for) transmitting and receiving wireless signals, including radio signals. Non-limiting examples of a communication device comprise a mobile station (MS) or mobile device such as a mobile phone or what is known as a ’smart phone’, a computer provided with a wireless interface card or other wireless interface facility (e.g., USB dongle), a personal data assistant (PDA) or a tablet provided with wireless communication capabilities, a machine-type communications (MTC) device, a Cellular Internet of things (CloT) device or any combinations of these or the like. The UE 300 may transmit or receive radio signals carrying communications (e.g., data or signalling). The communication may comprise one or more of voice, electronic mail (email), text message, multimedia, data, machine data and so on.

[0153] The UE 300 may receive radio signals over an air or radio interface 307 via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting radio signals. In Fig. 3 such an apparatus is a transceiver apparatus and is designated schematically by block 306. The transceiver apparatus 306 may comprise a radio part and associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the UE 300.

[0154] The UE 300 may be provided with at least one processor 301 , at least one memory ROM 302a, at least one RAM 302b and other possible components 303 for use in software and hardware aided execution of tasks it is designed to perform, including control of access to and communications with access systems and other communication devices. The at leastone processor 301 is coupled to the RAM 302b and the ROM 302a. The at least one processor 301 may be configured to execute an appropriate software code 308. The software code 308 may for example allow to perform one or more of the present aspects. The software code 308 may be stored in the ROM 302a.

[0155] The processor, storage and other relevant control apparatus can be provided on an appropriate circuit board and / or in chipsets. This feature is denoted by reference 304. The device may optionally have a user interface such as keypad 305, touch sensitive screen or pad, combinations thereof or the like. Optionally one or more of a display, a speaker and a microphone may be provided depending on the type of the device.

[0156] In practice, the radio coverage of a 5GS may be patchy and as a result a UE connected to the 5GS may frequently switch between the communicating with 5GS and an evolved packet system (EPS).

[0157] In this disclosure, a switch by a UE between communicating with the 5GS and communicating with an evolved packet system (EPS) may be referred to as inter-radio access technology (iRAT) mobility event.

[0158] Successive iRAT mobility events may cause several service operations between the SMSF and the UDM and between the UDM and the UDM’s backend (e.g., UDR, OneNDS) and therefore may cause significant resource consumption at the SMSF, the UDM and the UDM’s backend and signalling overhead between the SMSF, the UDM and the UDM’s backend.

[0159] Service operations between the SMSF and the UDM may comprise the SMSF transmitting a request to deregister the SMSF from the UDM (e.g., Nudm_UECM_Deregistration service operation), the SMSF transmitting a request to unsubscribe to a subscription data management (SDM) service provided by the UDM (e.g., Nudm_SDM_Unsubscribe service operation), the SMSF transmitting a request to register the SMSF with the UDM (e.g., Nudm_UECM_Registration service operation), the SMSF transmitting a request to get a SDM service provided by the UDM (e.g., Nudm_SDM_Get message) and the SMSF transmitting a request to subscribe to a SDM service provided by the UDM (e.g., transmitting a Nudm_SDM_Subscribe service operation).

[0160] One or more aspect of this disclosure provides a solution to reduce resource consumption at the SMSF, the UDM and the UDM’s backend and signalling transmitted between the SMSF, the UDM and the UDM’s backend when performing successive iRAT mobility events.

[0161] The solution may comprise configuring the SMSF to abstain from transmitting, to the UDM, the request to deregister the SMSF from the UDM (e.g., abstain from invoking a Nudm_UECM_Deregistration) and to abstain from transmitting, to the UDM, the request to unsubscribe to a SDM service provided at the UDM (e.g., abstain from invoking a Nudm_SDM_Unsubscribe) when a UE served by the SMSF switches from communicating with a 5GS to communicating with an EPS. The SMSF may retain a UE context for the UE stored at the SMSF (e.g., may not delete the UE context for the UE stored at the SMSF) and but instead marks the UE context for the UE stored at the SMSF as disabled.

[0162] The solution may comprise configuring the SMSF to abstain from transmitting, to the UDM, the request to register the SMSF with the UDM (e.g., abstain from invoking a Nudm_UECM_Registration), to abstain from transmitting, to the UDM, the request to get a SDM service provided at the UDM (e.g., abstain from invoking a Nudm_SDM_Get) and to abstain from transmitting, to the UDM, the request to subscribe to a SDM service provided by the UDM (e.g., abstain from transmitting a Nudm_SDM_Subscribe) when the UE served by the SMSF switches back from communicating with the EPS to communicating with the 5GS. The SMSF may mark the UE context for the UE stored at the SMSF as enabled.

[0163] An implementation of the solution will now be described in further details.Initial registration at the 5GS

[0164] A UE may operate in single registration mode (i.e. , the UE may only register with the 5GS or may only register with the EPS) or a dual registration mode (i.e., the UE may register with both the 5GS and the EPS). In the implementation described here, the UE is operating in single registration mode.

[0165] During registration with the 5GC (e.g., AMF) of the 5GS, the UE requests to send and receive SMS over NAS. The UE may request to send and receive SMS over NAS by including the request to send and receive SMS over NAS in a registration request that the UE sends to the AMF.

[0166] The AMF upon receipt of the request to register for SMS over NAS from the UE, determine whether the subscription of UE stored in the UDM allows SMS service for the UE (e.g., Nudm_SDM_Get). The AMF may determine that the subscription of UE stored in the UDM allows a SMS service for the UE.

[0167] The AMF may transmit, to the UDM, a request for a UE context for the UE stored at the UDM (e.g., Nudm_sdm_ue-context-smsf-data-retrieval). The UE context for the UE may comprise an identity (e.g., an identifier) of the SMSF and an address of the SMSF. The AMF may or may not receive, from the UDM, in response to the request for the UE contextfor the UE, the UE context for the UE that comprises the identity of the SMSF and the address of the SMSF.

[0168] The AMF may transmit, to the SMSF, a request to activate the UE at the SMSF (e.g., transmits a Nsmsf_SMService_Activate request). The AMF provides to the SMSF, in the request, the AMF’s NFINstanceld so that the SMSF knows which AMF serves the UE in order for the SMSF to communicate with the UE via the AMF during delivery of a SMS. The request to activate the UE at the SMSF (e.g., the Nsmsf_sms_Activate request) may include information which allow the SMSF to discover the correct UDM serving the UE, information about radio access type, the UE location, and the equipment identity of the UE (e.g., the PEI or lMEI).

[0169] The SMSF may transmit to the UDM a request to register the SMSF with the UDM (e.g., invoke or use a Nudm_UECM_Registration service operation to register the SMSF with the UDM). The UDM, upon receipt of the request to register the SMFS, registers the SMSF by storing an identity (e.g., identifier) of the SMSF and an address of the SMSF. The SMSF may transmit a request to get a SDM service provided by the UDM (e.g., invokes or uses a Nudm_SDM_Get to get a SDM service provided by the UDM). The SMSF may transmit a request to subscribe to a SDM service provided by the UDM (e.g., invokes or uses a Nudm_SDM_Subscribe to subscribe to a SDM service provided by the UDM). This aspect may be implemented as described in 3GPP TS 23.502 clause 4.13.3.1 (v18.3.0).

[0170] The SMSF may store a UE context for the UE at the SMSF or at the UDSF. The UE context for the UE may comprise a subscriber identifier of a subscriber associated with the UE, a UE identifier of the UE, an AMF identifier of the AMF serving the UE, a location of the UE and a timezone of the UE, an access type for the UE, information to locate the UDM serving the UE or trace data for the UE. The UE context for the UE may be represented at the SMSF or the UDSF by a resource (e.g., {apiRoot} / nsmsf-sms / <apiVersion> / ue- contexts / {supi}. This aspect may be implemented as per 3GPP TS 29.540 clause 6.11.3.3.2 (V18.2.0)

[0171] The UDM may store a UE context for the UE. The UE context for the UE may comprise the identity of the SMSF and the address of the SMSF.

[0172] The above operations are illustrated on Fig.4.

[0173] When a SMS needs to be delivered to the UE, the SC or SMS-GMSC may transmit, to the HSS, HLR, and / or UDM, a request to retrieve the identity of the SMSF and the address of the SMSF. The request may be referred to as a send routing information for short message (SRIForSM) request.

[0174] The UDM may transmit to the SC or SMS-GMSC, a response to the SRIForSM request, the response comprising the identity of the SMSF and the address of the SMSF. The response may be referred to as send routing information for short message (SRIF or SM) response. This aspect may be implemented as per 3GPP TS 23.502 clause 4.13.3.6 (V18.3.0).

[0175] The SC or SMS-GMSC may transmit, to the SMSF, the SMS.

[0176] The SMSF may transmit, to the UE, the SMS.Switching from 5GS to EPS

[0177] At some later point, the UE may determine to switch from communicating with a 5GS to communicating with an EPS.

[0178] After the UE determines to switch from communicating with a 5GS to communicating with an EPS, the UE connects to a base station of the E-UTRAN of the EPS. The UE transmits, to the MME of the EPS via the base station of the E-UTRAN, an attach request or a tracking area update (TAU) request to registerthe UE with the MME. The attach request or TAU request to register the UE with the MME may comprise a request for the UE to send and receive SMS. The request may be sent via 3GPP access.

[0179] The MME may transmit an Update Location request, to the HSS, to update a location of the UE.

[0180] If there is an interface between the HSS and the UDM (with or without N26), the HSS may cause the UDM to transmit, to the AMF, a notification e.g., Nudm_UECM_DeregistrationNotification), to deregister the UE from the AMF (. This aspect may be implemented as per in 3GPP TS 23.502 clause 4.11 .1.2.1 (v18.3.0).The sending of a notification (e.g., Nudm_UECM_DeregistrationNotification) to deregister the UE from the 5GC. The notification may comprise an enumeration deregistration reason indicating the reason for deregistering the UE at the AMF. This aspect may be implemented as per 3GGPP TS 29.503 clause 6.2.6.3.3 (v18.3.0). Here, the enumeration deregistration reason is “5GS_TO_EPS_MOBILITY”. In other words, the enumeration registration reason indicates that the reason for deregistering the UE at the AMF is mobility of the UE from communicating with a 5GS to communication with an EPS. The UDM and the AMF are both aware of the enumeration deregistration reason indicating the reason for deregistering the UE at the AMF.

[0181] If there is no interface between the HSS and the UDM (with N26), the AMF may deregister the UE after transmitting, to the MME, the UE context for the UE stored at the AMF.

[0182] The AMF may send, to the SMSF, a request to deactivate the UE at the SMSF (e.g., Nsmsf_SMService_Deactivate). The request to deactivate the UE at the SMSF (e.g., Nsmsf_SMService_Deactivate) may comprise a cause for deactivating the SMSF (e.g.,

[0183] deactivation cause). In other words, the request to deactivate the UE at the SMSF may comprise an indication of a cause for deactivating the UE at the SMSF. The cause for deactivating the UE at the SMSF may indicate that the UE has switched from communicating with the 5GS to communicating with the EPS (this switch is also referred to as inter-RAT mobility), that the UE no longer has a SMS subscription (also referred to as deregistration), that the UE has been switched off (also referred to as deregistration) or that the UE is out of the coverage area of the 5GS (also referred to as deregistration) .

[0184] The cause for deactivating the UE at the SMSF may comprise a flag, a bit, a string of characters or another indicator.

[0185] The cause for deactivating the UE at the SMSF may be conveyed to the SMSF as a query parameter in the request to deactivate the UE at the SMSF (e.g., Nsmsf_SMService_Deactivate), as an information element (IE) of a javascript object notation (json) payload in the request to deactivate the UE at the SMSF (e.g., Nsmsf_SMService_Deactivate) or a header in the request to deactivate the SMSF (e.g., Nsmsf_SMService_Deactivate). The header may be a hypertext transfer protocol (HTTP) header.

[0186] The cause for deactivating the UE at the SMSF may be conveyed as a query parameter in the request to deactivate the UE at the SMSF (e.g., a query parameter included in a Nsmsf_SMService_Deactivate service operation) or a header in the request to deactivate the UE at the SMSF (e.g., a header in the Nsmsf_SMService_Deactivate service operation). The request to deactivate the UE using a DELETE operation, a PUT operation or a POST operation. The PUT operation may reused if the UE is simultaneously registered to a 5GC via 3gpp access and non-3gpp access and then the UE is deregistered from the 5GC via 3gpp access and remains registered via non-3gpp access, or vice versa.

[0187] The cause for deactivating the UE at the SMSF may be conveyed as javascript object notation (json) payload in a request to deactivate the UE at the SMSF (e.g., in a Nsmsf_SMService_Deactivate service operation) using a POST operation.

[0188] The cause for deactivating the UE at the SMSF may be URI query parameter that is included in a request to deactivate the UE at the SMSF as follows.URI query parameter

[0189] The SMSF may determine the cause for deactivating the UE at the SMSF based on URI query parameter (e.g., deactivation cause) included in the request to deactivate the UE at the SMSF (e.g., Nsmsf_SMService_Deactivate).

[0190] The SMSF may determine whether to transmit, to the UDM, a request to deregister the SMSF at the UDM (e.g., Nudm_UECM_Deregistration) based on the cause for deactivating the UE at the SMSF.

[0191] The SMSF may determine whether to transmit, to the UDM, a request to unsubscribe to a SDM service provided by the UDM (e.g., Nudm_SDM_Unsubscribe) based on the cause for deactivating the UE at the SMSF.

[0192] When the cause for deactivating the UE at the SMSF indicates that the UE has switched from communicating with the 5GS to communication with the EPS (e.g., iRAT mobility event), the SMSF may determine to abstain from transmitting, to the UDM, the request to deregister the SMSF at the UDM (e.g., Nudm_UECM_Deregistration). The SMSF may determine to abstain from transmitting the request to unsubscribe to a SDM service provided by the UDM (e.g., Nudm_SDM_Unsubscribe). The SMSF may or may not delete the resource (e.g., URI) that represents the UE context for the UE stored at the SMSF or the UDSF (e.g., {apiRoot} / nsmsf-sms / <apiVersion> / ue-contexts / {supi}). The SMSF may not serve subsequent requests on the resource that represents the U E context for the U E stored at the SMSF or the UDSF. The SMSF may not delete the UE context for the UE stored at the SMSF. Instead, the SMSF may mark the UE context for the UE stored at the SMSF or the UDSF as disabled (i.e. , mark the UE context for the UE as inactive or deactivated). The UDM may not delete the identity of the SMSF and the address of the SMSF stored at the UDM. In other words, the identity of the SMSF and the address of the SMSF are still storedat the UDM and the SDM service subscription for the SMSF (e.g., the subscription for SDM service provided by the UDM for SMSF) is still active.

[0193] When the cause for deactivating the UE at the SMSF indicates that the UE no longer has an SMS subscription, the SMSF may determine to transmit, to the UDM, the request to deregister the SMSF at the UDM (e.g., Nudm_UECM_Deregistration). The SMSF may transmit, to the UDM, the request to deregister the SMSF at the UDM (e.g., Nudm_UECM_Deregistration). The SMSF may determine to transmit, to the UDM, the request to unsubscribe to a SDM service provided by the UDM (e.g., Nudm_SDM_Unsubscribe). The SMSF may transmit, to the UDM, the request to unsubscribe to a SDM service provided by the UDM (e.g., Nudm_SDM_Unsubscribe). The SMSF may delete the resource (e.g., URI) that represents the UE context for the UE stored at the SMSF or the UDSF (e.g., {apiRoot} / nsmsf-sms / <apiVersion> / ue-contexts / {supi}). The SMSF may not serve subsequent requests on the resource (e.g., URI) that represents the UE context for the UE stored at the SMSF or the UDSF. The SMSF may delete the UE context for the UE stored at the SMSF or the UDSF. The UDM may delete the identity of the SMSF and the address of the SMSF stored at the UDM. In other words, the UDM no longer has the identity of the SMSF and the address of the SMSF stored at the UDM and retain the SDM service subscription from the SMSF. In other words, the identity of the SMSF and the address of the SMSF are no longer stored at the UDM and the SDM service subscription from the SMSF is no longer active.

[0194] When the cause for deactivating the UE at the SMSF indicates that the UE has been switched off, the SMSF may determine to transmit, to the UDM, the request to deregister the SMSF at the UDM. The SMSF, in response to determining to transmit, to the UDM, the request to deregister the SMSF at the UDM, transmits, to the UDM, the request to deregister the SMSF at the UDM (e.g., Nudm_UECM_Deregistration). The SMSF may determine to transmit, to the UDM, the request to unsubscribe to a SDM service provided by the UDM (e.g., Nudm_SDM_Unsubscribe). The SMSF may transmit, to the UDM, the request to unsubscribe to a SDM service provided by the UDM (e.g., Nudm_SDM_Unsubscribe). The SMSF may delete the resource (e.g., URI) that represents the UE context for the UE stored at the SMSF or the UDSF (e.g., {apiRoot} / nsmsf- sms / <apiVersion> / ue-contexts / {supi}). The SMSF may not serve subsequent requests on this resource. The SMSF may delete the UE context for the UE stored at the SMSF. The UDM may delete the identity of the SMSF and the address of the SMSF stored at the UDM or the UDSF. In other words, the identity of the SMSF and the address of the SMSF are nolonger stored at the UDM and the SDM service subscription from the SMSF is no longer active.

[0195] Here, the cause for deactivating the UE at the SMSF indicates that the UE has switched from communicating with the 5GS to communicating with the EPS (i.e., iRAT mobility). The SMSF may determine to abstain from transmitting, to the UDM, the request to deregister the SMSF at the UDM. The SMSF may or may not delete the resource (e.g., URI) that represents the UE context for the UE stored at the SMSF or the UDSF (e.g., {apiRoot} / nsmsf-sms / <apiVersion> / ue-contexts / {supi}). The SMSF may not serve subsequent requests on this resource. The SMSF may not delete the UE context for the UE stored at the SMSF or the UDSF. The SMSF may mark the UE context for the UE stored at the SMSF or the UDSF as disabled (i.e., inactive or deactivated). The UDM may not delete the identity of the SMSF and the address of the SMSF stored at the UDM.

[0196] These operations are illustrated on Fig.4.

[0197] The UE deregistration procedure described in 3GPP TS 23.502 clause 4.13.3.2 is to be changed as follows based on the aspects of the present disclosure described herein.

[0198] 4 13.3.2 Deregistration procedures for SMS o ver NA SIf UE indicates to AMF that it no longer wants to send and receive SMS over NAS (e.g., not including "SMS supported" indication in subsequent Registration Request message) or AMF considers that UE is deregistered on specific Access Type(s) or AMF receives Deregistration Notification from UDM for specific Access Type(s) indicating UE Initial Registration, Subscription Withdrawn or 5GS to EPS Mobility as specified in clause 5.2.3.2.2, then depending on the Deactivation cause values, the AMF, the SMSF and the UDM proceed as follows:AMF may, if the UE is not registered at other Access Type at the AMF any more, unsubscribe from SMS Subscription data changes notification with the UDM by means of the Nudm_SDM_Unsubscribe service operation.AMF invokes Nsmsf_SMService_Deactivate service operation to trigger the release of UE Context for SMS on SMSF for the impacted Access Type(s) based on local configurations. If the reason for the deactivation procedure for SMS is Inter-RAT mobility or Attach procedure, then the AMF shall indicate Deactivation cause "Inter-RAT mobility" in the Nsmf_SM Service Deactivate. Otherwise, the AMF shall indicate Deactivation cause "Deregistration".AMF may, if the UE is not registered at other Access Type at the AMF anymore, delete or deactivate the stored SMSF address in its UE Context.If the Deactivation cause is not "Inter-RAT mobility", the SMSF unsubscribes from SMS Management Subscription data changes notification with the UDM by means of the Nudm_SDM_Unsubscribe service operation if the UE is not registered at other Access Type for SMS over NAS service at the SMSF anymore.If the Deactivation cause is not "Inter-RAT mobility", the SMSF shall invoke Nudm_UECM_Deregistration (SUPI, NF ID, Access Type) service operation from UDM to trigger UDM to delete SMSF address of the UE for the impacted Access Type(s). The SMSF also removes the UE Context for SMS for the impacted Access Type(s), including AMF address. Otherwise, the SMSF locally marks the UE context for SMS as deactivated.If the Deactivation cause is "Deregistration", the UDM may update UE context in SMSF in UDR by Nudr_DM_Update (SUPI, Subscription Data, SMS Subscription data, SMSF address). The UDM may remove the corresponding subscription of data change notification in UDR by Nudr_DM_Unsubscribe service operation.If the UDM receives deregistration request from the HSS, the UDM shall set the purge flag in its response to indicate that the HSS shall not include the SMSF address to the SMS-SC.

[0199] When a SMS needs to be delivered to the UE, the SC or SMS-GMSC may transmit, to the UDM via the HSS, a SRIForSM request to retrieve the identity of the SMSF and the address of the SMSF.

[0200] As explained above, the UDM has transmitted, to the AMF, a notification, to deregister the UE at the AMF (e.g., Nudm_UECM_DeregistrationNotification). The notification to deregister the UE for SMS over NAS at the AMF (e.g., Nudm_UECM_DeregistrationNotification) may comprise an enumeration deregistrationreason indicating the reason for deregistering the UE at the AMF. Here, the enumeration deregistration reason is “5GS_TO_EPS_MOBILITY”.

[0201] The UDM may determine whether to transmit the identity of the SMSF and the address of the SMSF based on the enumeration deregistration reason.

[0202] When the enumeration deregistration reason is “5GS_TO_EPS_MOBILITY”, the UDM may determine to abstain from transmitting a SRIForSM response comprising the identity of the SMSF and the address of the SMSF.

[0203] If the UDM stores an alternative identity and an alternative address in the 2GC / 3GC, EPC or IMS, the UDM may determine to transmit a SRIForSM response comprising the alternative identity and the alternative address in the 2GC / 3GC, EPC or IMS. The alternative identity and the alternative address may comprise the identity of the IP-SM- GW and the address of the IP-SM-GW. The alternative identity and the alternative address may comprise the identity of the MME and the address of the MME. The alternative identity and the alternative address may comprise the identity of the MSC and the address of the MSC. The UDM may transmit the SRIForSM response comprising the alternative identity and an alternative address in the 2GC / 3GC, EPC or IMS. In this way, SMS delivery may remain reliable.

[0204] If the UDM does not store an alternative identity and an alternative address in the 2GC / 3GC, EPC or IMS, the UDM may transmit a message indicating an error.

[0205] When the enumeration deregistration reason is not “5GS_TO_EPS_MOBILITY”, the UDM may determine to transmit a SRIForSM response comprising the identity of the SMSF and the address of the SMSF. The UDM may transmit the SRIForSM response comprising the identity of the SMSF and the address of the SMSF.

[0206] Here, the enumeration deregistration reason is “5GS_TO_EPS_MOBILITY”. The UDM may determine to abstain from transmitting a SRIForSM response comprising the identity of the SMSF and the address of the SMSF. The UDM may determine to transmit, to the SMSC via the HSS, a SRIForSM response comprising an alternative identity and an alternative address in the 2GC / 3GC, EPC or IMS. The alternative identity and the alternative address may comprise the identity of the IP-SM-GW and the address of the IP-SM-GW. The alternative identity and the alternative address may comprise the identity of the MME and the address of the MME. The alternative identity and the alternative address may comprise the identity of the MSC and the address of the MSC. The UDM may transmit the SRIForSM response comprising the alternative identity and an alternative address in the 2GC / 3GC, EPC or IMS.

[0207] These operations are illustrated on Fig. 5 (MT SMS delivery while UE is connected to EPS).Switching back from EPS to 5GS

[0208] At some later point, the UE may determine to switch back from communicating with the EPS to communicating with the 5GS.

[0209] The UE may transmit, via a 5G RAN (e.g., 3GPP access)), a request to register the UE at the 5GS. The request may be for SMS over 5G non-access stratum (NAS) (e.g., SMS service to be provided over NAS).

[0210] The 5G RAN may receive the request and select a AMF and may transmit, to the AMF, the request to register the UE with the 5GS.

[0211] The AMF may determine that the UE has a SMS subscription.

[0212] The AMF may transmit, to the UDM, a request to retrieve the identity and the address of the SMSF (e.g., transmit a Nudm_SDM_Get UE-Context-smsf-data-retrieval message to retrieve the identity and the address of the SMSF). This aspect may be implemented as per 3GPP TS 23.502 clause 4.13.3.1 (v18.3.0) and 3GPP TS 23.503 clause 5.2.2.2.12 (v18.3.0).

[0213] The UDM may transmit, to the AMF, the identity and the address of the SMSF.

[0214] The AMF may select the SMSF. The AMF may transmit, to the SMSF, a request to activate the UE at the SMSF. The SMSF may be the previous SMSF (i.e., SMSF selected for the initial registration of the UE at the 5GS) or another SMSF. Here, the SMSF may be the previous SMSF.

[0215] The SMSF determines whether the SMSF or the UDSF stores a UE context for the UE and the UE context for the UE is marked as disabled (i.e., inactive or deactivated). Based on the SMSF determining that the SMSF or the UDSF stores a UE context for the UE and the UE context for the UE is marked as disabled (i.e., inactive or deactivated), the SMSF may determine to transmit, to the UDM, a request to register the SMSF at the UDM, a request to get a SDM service provided at the UDM and a request to subscribe to the SDM service provided at the UDM

[0216] For example, when the SMSF or the UDSF stores a UE context for the UE and the UE context for the UE is marked as disabled (i.e., inactive or deactivated), the SMSF determines to abstain from transmitting (e.g., determines not to transmit), to the UDM, a request to register the SMSF at the UDM, a request to get a SDM service provided at the UDM and a request to subscribe to the SDM service provided at the UDM. Insteaad, theSMSF marks the UE context for the UE stored at the SMSF or the LIDSF as enabled (i.e., active). In this way, the resource consumption at the SMSF, the UDM and the UDM’s backend (e.g., UDR, OneNDS) and the amount of signalling transmitted between the SMSF, the UDM and the UDM’s backend (e.g., signalling overhead in the 5GC) may be reduced.

[0217] When the SMSF or the UDSF does not store a UE context for the UE and the UE context for the UE is marked as disabled (i.e., inactive or deactivated), the SMSF may determine to transmit, to the UDM, a request to register the SMSF at the UDM, a request to get a SDM service provided at the UDM and a request to subscribe to the SDM service provided at the UDM. The SMSF may transmit, to the UDM, a request to register the SMSF at the UDM, a request to get a SDM service provided at the UDM and a request to subscribe to the SDM service provided at the UDM. The SMSF may store a UE context for the UE at the SMSF or the UDSF.

[0218] Here, the SMSF or the UDSF stores a UE context for the UE and the UE context for the UE is marked as disabled (i.e., inactive or deactivated). The SMSF may determine to abstain from transmitting, to the UDM, a request to register the SMSF at the UDM, a request to get a SDM service provided at the UDM and a request to subscribe to the SDM service provided at the UDM. The SMSF may mark the UE context for the UE stored at the SMSF or the UDSF as enabled (i.e., active).

[0219] These operations are illustrated on Fig. 6 (UE registration after UE returns to communicating with a 5GS).It will be understood that the 5GC does not necessarily comprise a single SMSF. The 5GC may comprise multiple SMSFs (e.g., SMSF1 and SMSF2). The AMF may not necessarily select the previous SMSF (e.g., SMSF1) and may select another SMSF (e.g., SMSF2) when the UE switches back from communicating with the 5GS to communicating with the EPS.

[0220] The AMF may transmit, to the other SMSF (e.g., SMSF2), a request to activate the UE at the SMSF (e.g., a Nsmsf_SMService_Activate request).

[0221] The other SMSF may transmit a request to register the other SMSF at the UDM (e.g., Nudm_UECM_Registration). The other SMSF may transmit a request (e.g., Nudm_SDM_Get) to get a SDM service provided by the UDM. The other SMSF may transmit a request to subscribe (e.g., Nudm_SDM_Subscribe) to a SDM service provided by the UDM.

[0222] The previous SMSF may determine whether a timer associated with the UE context for the UE stored at the SMSF or the UDSF has expired. When the timer associatedwith the UE context for the UE stored at the SMSF has expired, the previous SMSF may delete the UE context for the UE stored at the SMSF or the UDSF.

[0223] The UDM may determine whether a timer associated with the identity of the previous SMSF and the address of the previous SMSF has expired. When the timer associated with the identity of the previous SMSF and the address of the previous SMSF has expired, the UDM may delete the identity of the previous SMSF and the address of the previous SMSF.

[0224] The UDM may determine whether a timer associated with the subscription to the SDM provided by the UDM to the previous SMSF has expired. When the timer associated with the subscription to the SDM provided by the UDM to the previous SMSF has expired, the UDM may delete the subscription to the SDM provided by the UDM to the previous SMSF.

[0225] These operations are illustrated on Fig. 7.

[0226] Fig. 8 shows a schematic representation of a flowchart of a method for a SMSF in a communication system.

[0227] At step 800, the SMSF may receive, from an AMF in the communication system, a request to deactivate a UE at the SMSF, wherein the request to deactivate the UE at the SMSF comprises a cause for deactivating the UE at the SMSF.

[0228] At step 802, the SMSF may, based on the cause for deactivating the user equipment at the SMSF: transmit, to a UDM in the communication system, a request to deregister the SMSF at the UDM and delete the UE context for the UE; or mark a UE context for the UE as inactive, wherein deregistering the SMSF at the UDM comprises deleting at least one of an identity of the SMSF or an address of the SMSF stored at the UDM.

[0229] Fig. 9 shows a schematic representation of a flowchart of a method for an AMF of a communication system.

[0230] At step 900, the AMF may receive, from a UDM in the communication system, a notification to deregister a UE at the AMF, wherein the notification comprises a cause for deregistering the UE at the AMF.

[0231] At step 902, the AMF may transmit a request to deactivate the UE at a SMSF in the communication system, wherein the request to deactivate the UE at the SMSF comprises a cause for deactivating the UE at the SMSF, wherein the cause for deactivating the UE at the SMSF is based on the cause for deregistering the UE at the AMF.

[0232] Fig. 10 shows a schematic representation of a flowchart of a method for a UDM (or performed by a UDM) of a communication system.

[0233] At step 1000, the UDM may receive, from a SMSC or an IP-SM-GW, a request to retrieve at least one of an identity of a SMSF in the communication system or an address of a SMSF in the communication system.

[0234] At step 1002, the UDM may receive, from a HSS in another communication system, an indication that a UE has switched from the communication system to the other communication system.

[0235] At step 1004, the UDM may, based on the indication that a UE has switched from the communication system to the other communication system, transmit at least one alternative identity or alternative address or transmit a message indicating an error.

[0236] Fig. 11 shows a schematic representation of non-volatile memory media 1100 storing instructions which when executed by a processor allow the processor to perform one or more of the steps of the methods of Fig. 8 to Fig. 10.

[0237] It is noted that while the above describes example embodiments, there are several variations and modifications which may be made to the disclosed solution without departing from the scope of the present invention.

[0238] It will be understood that although the above concepts have been discussed in the context of a 5GS, one or more of these concepts may be applied to other cellular systems.

[0239] The embodiments may thus vary within the scope of the attached claims. In general, some embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although embodiments are not limited thereto. While various embodiments may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

[0240] The embodiments may be implemented by computer software stored in a memory and executable by at least one data processor of the involved entities or by hardware, or by a combination of software and hardware. Further in this regard it should be noted that anyprocedures, e.g., as in Fig. 8 to Fig. 10, may represent program steps, or interconnected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions. The software may be stored on such physical media as memory chips, or memory blocks implemented within the processor, magnetic media such as hard disk or floppy disks, and optical media such as for example DVD and the data variants thereof, CD.

[0241] The memory may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The data processors may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASIC), gate level circuits and processors based on multi-core processor architecture, as non-limiting examples.

[0242] Alternatively or additionally some embodiments may be implemented using circuitry. The circuitry may be configured to perform one or more of the functions and / or method steps previously described. The circuitry may be provided in a base station and / or in a user equipment.

[0243] As used in this application, the term “circuitry” may refer to one or more or all of the following:(a) hardware-only circuits (such as only analogue and / or digital circuits);(b) combinations of hardware circuits and software, such as:(i) a combination of analogue and / or digital hardware circuit(s) with software / firmware and(ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as the communications device or base station to perform the various functions previously described; and(c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0244] This definition of circuitry applies to all uses of this term “means” in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multipleprocessors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example integrated device.

[0245] The foregoing description has provided by way of exemplary and non-limiting examples a full and informative description of some embodiments However, various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings and the appended claims. However, all such and similar modifications of the teachings will still fall within the scope as defined in the appended claims.

Claims

CLAIMS:

1. A method for a short message service function in a communication system, the method comprising: receiving, from an access and mobility management function in the communication system, a request to deactivate a user equipment at the short message service function, wherein the request to deactivate the user equipment at the short message service function comprises a cause for deactivating the user equipment at the short message service function; and based on the cause for deactivating the user equipment at the short message service function: transmitting, to a unified data management in the communication system, a request to deregister the short message service function at the unified data management and deleting a user equipment context for the user equipment; or marking a user equipment context for the user equipment as inactive, wherein deregistering the short message service function at the unified data management comprises deleting at least one of an identity of the short message service function or an address of the short message service function stored at the unified data management.

2. The method of claim 1 , comprising: determining that the cause for deactivating the user equipment at the short message service function indicates that the user equipment has switched from the communication system to another communication system; determining, based on the cause for deactivating the user equipment at the short message service function, to abstain from transmitting, to the unified data management in the communication system, the request to deregister the short message service function at the unified data management and mark a user equipment context for the user equipment as inactive; and marking the user equipment context for a user equipment as inactive.

3. The method of claim 2, wherein the method comprises: determining, based on the cause for deactivating the user equipment at the short message service function, to abstain from transmitting, to the unified data management, a request to unsubscribe to a subscription data management service provided at the unified data management and mark a user equipment context for the user equipment as inactive; and marking the user equipment context for the user equipment as inactive.

4. The method of any of claims 1 to 3, wherein the method comprises: determining that a timer associated with the user equipment context for the user equipment has expired; and deleting the user equipment context for the user equipment.

5. The method of claim 2 or claim 3, comprising: receiving, from the access and mobility management function, a request to activate the user equipment at the short message service function; determining that the user equipment context for the user equipment is marked as inactive; and determining, based on the user equipment context for the user equipment being marked as inactive, to abstain from transmitting, to the unified data management, a request to register the short message service function at the unified data management.

6. The method of claim 5, comprising: determining, based on the user equipment context for the user equipment being marked as inactive, to abstain from transmitting, to the unified data management, a request to get a subscription data management service provided at the unified data management.

7. The method of claim 5 or claim 6, wherein the method comprises: determining, based on the context for the user equipment being marked as inactive, to abstain from transmitting, to the unified data management, a request to subscribe to a subscription data management service provided at the unified data management.

8. The method of any of claims 5 to 7, wherein the method comprising: marking the user equipment context for the user equipment as enabled.

9. The method of claim 1 , comprising: determining that the cause for deactivating the user equipment at the short message service function does not indicate that the user equipment has switched from the communication system to another communication system; determining, based on the cause for deactivating the user equipment at the short message service function, to transmit, to the unified data management, the request to deregister the short message service function at the unified data management and to delete a user equipment context for the user equipment; transmitting, to the unified data management, the request to deregister the short message service function at the unified data management; and deleting the user equipment context for the user equipment.

10. The method of claim 9, wherein the cause for deactivating the user equipment at the short message service function indicates that: the user equipment does not have a short message service subscription; the user equipment is switched off; or the user equipment is out of the coverage of the communication system.11 . The method of claim 9 or claim 10, comprising: receiving, from the access and mobility management function, a request to activate the user equipment at the short message service function; determining, based on the context for the user equipment being deleted, to transmit, to the unified data management, a request to register the short message service function at the unified data management; and transmitting, to the unified data management, a request to register the short message service function at the unified data management.

12. The method of any of claims 9 to 11 , comprising: determining, based on the context for the user equipment being deleted, to transmit, to the unified data management, a request to get a subscription data management service provided at the unified data management; and transmitting, to the unified data management, a request to get a subscription data management service provided at the unified data management.

13. The method of any of claims 9 to 11 , wherein the method comprises: determining, based on the context for the user equipment being deleted, to transmit, to the unified data management, a request to subscribe to a subscription data management service provided at the unified data management; and transmitting, to the unified data management, a request to subscribe to a subscription data management service provided at the unified data management.

14. The method of any of claims 1 to 13, wherein the cause for deactivating the user equipment at the short message service function is conveyed as: a query parameter in the request to deactivate the user equipment at the short message service function; an information element of a javascript object notation body in the request to deactivate the user equipment at the short message service function; or a header in the request to deactivate the user equipment at the short message service function.

15. The method of any of claims 1 to 14, wherein the user equipment context for the user equipment is stored at the short message service function or at an unstructured data storage function.

16. The method of any of claims 1 to 15, wherein the short message service function serves a user equipment in single registration mode.

17. The method of any of claims 1 to 16, wherein the short message service function serves the user equipment for 3GPP access or non-3GPP access.

18. A method for an access and mobility management function in a communication system, the method comprising: receiving, from a unified data management in the communication system, a notification to deregister a user equipment at the access and mobility management function, wherein the notification comprises a cause for deregistering the user equipment at the access and mobility management function; and transmitting a request to deactivate the user equipment at a short message service function in the communication system, wherein the request to deactivate the user equipment at the short message service function comprises a cause for deactivating the user equipment at the short message service function, wherein the cause for deactivating the user equipment at the short message service function is based on the cause for deregistering the user equipment at the access and mobility management function.

19. The method of claim 18, wherein at least one of the cause for deactivating the user equipment at the short message service function or the cause for deregistering the user equipment at the access and mobility management function indicates that: the user equipment switches from the communication system to another communication system; the use equipment does not have a short message service subscription; the user equipment is switched off; or the user equipment is out of the coverage of the communication system.

20. A method for a unified data management in a communication system, the method comprising: receiving, from a short message service centre or an internet protocol short message gateway, a request to retrieve at least one of an identity of a short message service function in the communication system or an address of a short message service function in the communication system;receiving, from a home subscriber server in another communication system, an indication that a user equipment has switched from the communication system to the other communication system; and based on the indication that a user equipment has switched from the communication system to the other communication system transmitting at least one alternative identity or alternative address or transmitting a message indicating an error.21 . The method of claim 20, comprising: determining, based on the indication that a user equipment has switched from the communication system to the other communication system, to abstain from transmitting to the short message service centre or the internet protocol short message gateway, at least one of the identity of the short message service function or the address of the short message service function and transmit, to the short message service centre, at least one alternative identity or alternative address.

22. The method of claim 21 , wherein the alternative identity comprises the identity of an internet protocol short message gateway, a mobility management entity, a serving general packet radio service support node or a mobile switching centre; or wherein the alternative address comprises the address of an internet protocol short message gateway, a mobility management entity, a serving general packet radio service support node or a mobile switching centre.

23. An apparatus for a communication system, the apparatus comprising: a short message service function of the communication system, short message service configured to perform the method of any of claims 1 to 17.

24. An apparatus for a communication system, the apparatus comprising: access and mobility management function of the communication system, the apparatus configured to perform the method of claim 18 or 19.

25. An apparatus for a communication system, the apparatus comprising: a unified data management entity in a communication system, the unified data management entity configured to perform the method of any of claims 20 to 22.

26. A computer program comprising computer executable code which when run on at least one processor is configured to perform the method of any of claims 1 to 22.

27. A computer-readable medium comprising computer executable code which when executed by at least one processor is configured to perform the method of any of claims 1 to 22.

Images